Physchem doi: 10.3390/physchem6030057

Authors: Xiaxia Cui Xinchao Zhou Qiang Tang Jau Tang

We formulate a gauge-invariant phenomenological theory for a charged three-component condensate in an anisotropic layered superconductor. The construction is conditional on a material-specific pairing calculation selecting an isolated, predominantly triplet channel; it does not infer triplet pairing from layering or spin–orbit coupling alone. The order parameter is represented equivalently by a spin-1 spinor, a complex d-vector, and a pure-vector complex quaternion. Only the mapping and the density-spin bilinear are retained in the main text. A static Ginzburg–Landau functional then yields axial-polar, planar-polar, easy-axis polarized, and broken-axisymmetry mean-field states. Conservative Gross–Pitaevskii dynamics are introduced only as an additional composite-boson limit, not as a generic consequence of the Ginzburg–Landau theory. In that limit, analytic spectra are given for the axial-polar and easy-axis phases: the transverse spin branch softens at the axial-polar to broken-axisymmetry boundary, whereas crystal locking gaps the transverse magnon of the polarized phase. We do not claim a closed analytic spectrum for the mixed broken-axisymmetry phase. The static transverse current-response kernel provides a quantitative link between penetration-depth anisotropy and the gradient tensor. Ideal Bose condensation and BKT formulas are stated only in their controlled three- and two-dimensional limits. The framework therefore supplies a compact, falsifiable set of phase, mode, and response relations without introducing additional quaternionic degrees of freedom.

Physchem doi: 10.3390/physchem6030056

Authors: Andrey Timofeev Alexander Bratchikov Alexander Anufriev

The solvent-accessible surface area (SASA) of amino acid residues is a crucial parameter for protein structure analysis; however, precise computational methods such as FreeSASA are computationally expensive. As an alternative, empirical approximations based on residue interaction network (RIN) graphs can offer high speed while maintaining acceptable accuracy. In this study, we propose and validate three empirical functions for estimating relative SASA—approx_sasa, surface_score, and exp_sasa—using node degree as the sole argument. We present a comparative analysis of two graph construction approaches: the classical Cα-graph (8 Å threshold) and the heavy-atom graph (HAG, 5.0 Å threshold). Parameters were calibrated on a dataset of 509 protein structures (128,794 residues) using the true relative SASA calculated by the FreeSASA library. An extended set of 11 topological features was also developed and validated. Ensemble models (Random Forest, XGBoost) achieved a best performance of MAE = 0.057 ± 0.033 and Pearson r = 0.915 ± 0.080 on HAG, outperforming graph neural networks (GCN, GAT, GraphSAGE) in this setting. The empirical formulas demonstrate extreme computational efficiency (0.008 ms per structure), ~26,000× faster than FreeSASA, making them suitable for large-scale pipelines requiring both speed and interpretability. Random Forest on HAG is recommended for applications requiring maximum accuracy, while GraphSAGE on HAG is a viable deep learning alternative.

Physchem doi: 10.3390/physchem6030055

Authors: Mauricio Aarón Pérez-Romero Iván Lenín Cruz-Jaramillo Leonardo Gabriel Vega-Macotela Armando Josué Piña-Díaz

Greywater treatment is an essential component of sustainable water management strategies, particularly in regions experiencing water scarcity. This study presents a quantitative comparative evaluation of three conventional inorganic coagulants—aluminum sulfate (Al2(SO4)3), ferric sulfate (Fe2(SO4)3), and ferric chloride (FeCl3)—for domestic greywater treatment using standardized jar test procedures. The initial turbidity of the greywater was 186 ± 5 NTU. Coagulant performance was assessed based on final turbidity, removal efficiency, and pH variation, with dosages expressed as mg of active metal per liter to ensure comparability. Ferric chloride exhibited the highest turbidity removal efficiency, achieving a maximum removal efficiency of 96.2 ± 0.8% at 68.8 mg Fe/L and reducing turbidity to 7 ± 1 NTU. Ferric sulfate achieved a maximum removal efficiency of 92.5 ± 1.2%, while aluminum sulfate reached 84.9 ± 1.4% under the evaluated conditions. Statistical analysis confirmed significant differences among coagulants at intermediate and high dose ranges (p < 0.05). The results indicate that ferric chloride provides the most effective clarification performance for the tested greywater matrix, while maintaining final pH values within a suitable range for non-potable reuse. This study contributes to coagulant selection for decentralized greywater treatment systems through standardized, quantitative comparison under identical operational conditions.

Physchem doi: 10.3390/physchem6030054

Authors: Kasumi Kobayashi Nao Kodama Florencio Arce Gerard Lee See Yutaka Inoue

Low-molecular-weight lychee polyphenol (Lyp), a standardized oligomeric polyphenol derived from Litchi chinensis fruit, possesses potent antioxidant activity but is susceptible to physicochemical instability, which may limit its practical application. In this study, freeze-dried systems of Lyp with α-, β-, and γ-cyclodextrins (CDs) were prepared to investigate the effects of cyclodextrins on the physicochemical properties and antioxidant activity of Lyp. Powder X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, near-infrared spectroscopy, and solution-state NMR were employed to characterize the prepared systems. Freeze-drying produced amorphous Lyp/CD systems accompanied by enhanced thermal stability and changes in the hydrogen-bonding environment compared with the corresponding physical mixtures. Solution-state 1H NMR and NOESY analyses suggested molecular association between Lyp constituents and cyclodextrins, with the βCD system exhibiting the most pronounced spectral changes. Consistent with these physicochemical findings, the freeze-dried βCD system showed the greatest enhancement of DPPH radical scavenging activity among the three cyclodextrins examined. These results suggest that βCD provides the most favorable molecular environment for Lyp, leading to improved physicochemical characteristics and antioxidant performance. The present findings demonstrate that freeze-drying combined with β-cyclodextrin is an effective strategy for improving the physicochemical performance and antioxidant functionality of low-molecular-weight lychee polyphenol.

Physchem doi: 10.3390/physchem6030053

Authors: Vincenzo Villani

In this study, the Boscovich curve of 1763 is reinterpreted as a mean-field potential for interacting particles in condensed matter. In a dense many-body system, each particle experiences an effective potential arising from the average distribution of all the others. This mean-field potential, which exhibits alternating maxima (energy barriers) and minima (coordination shells), thereby reducing the complexity of the N-body problem to an effective two-body radial problem, with the correlation distance r as the key variable. The relationship between the PMF and the radial distribution function g(r) is given by the Kirkwood equation UB(r) = −kT ln g(r), which provides a multi-well potential in condensed matter. Furthermore, the system is described by the Fisher density functional equation for the correlation amplitudes, −2kT ∇2ψ(r) + UB(r)ψ(r) = μψ(r) whose eigenvalues μi correspond to potential levels and whose eigenfunctions ψi are the correlation amplitudes of the coordination shell structure. Based on the multi-well potential picture, the oscillatory behavior of UB(r) is modeled analytically by a weighted sum of Lennard-Jones potentials, modulated by sigmoid functions. The parameters—well depths, widths, and coordination distances—are assigned on the basis of known structural properties of the system, derived either from experimental data or from geometric models such as FCC or HCP lattices. The radial distribution function is then reconstructed as a linear combination of the squared eigenfunctions obtained from the Fisher equation. The resulting discrete eigenvalue spectrum provides a spectral interpretation of the shell structure of condensed matter, wherein the complexity of many-body interactions is encoded in a hierarchy of correlation modes, each associated with a specific coordination shell. Unlike classical DFT—which relies on approximate excess free-energy functionals—and Ornstein–Zernike theory—which requires closure approximations—our approach provides a direct spectral interpretation of the coordination shell structure through the eigenvalue spectrum of the Fisher equation, where the PMF acts as the effective potential and the radial distribution function is reconstructed as a combination of squared eigenfunctions. The method is validated for liquid argon and FCC lattices and establishes a historical connection with Boscovich’s curve as a statistical potential.

Physchem doi: 10.3390/physchem6030052

Authors: Paulo Ernesto Marchezi Stella Maragkaki Andreas Michael Zafer Hawash Leif Ericsson Kyriaki Savva Marcin Zając Emmanuel Stratakis Ellen Moons

Graphene oxide (GO) and reduced graphene oxide (rGO) are widely studied two-dimensional carbon nanomaterials for optoelectronic devices. Because the oxygen content and degree of reduction govern the electronic structure of GO-derived films, controlling the reduction process is essential for tailoring their properties. Laser-induced reduction provides a tunable, contact-free route to transparent and conductive graphene-based layers. In this work, 80 nm spray-coated GO layers were reduced using a KrF excimer laser (248 nm, 20 ns) at a fluence of 20 mJ cm−2, while systematically varying the number of laser pulses (LP) from 1 to 1000. We tuned the degree of GO reduction by stepwise increasing the number of LP and followed the resulting changes in surface composition using X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy. The surface composition evolves non-monotonically with the number of laser pulses, revealing a multi-step reduction mechanism. At low laser doses, epoxide groups are preferentially removed or converted, generating a more disordered distribution of hydroxyl-containing sites on the GO sheets. At intermediate laser doses, oxygen-containing groups are depleted, and sp2 conjugation is restored. After extended irradiation in air, however, oxygenated surface species partially re-form. Conductivity measurements show that the sheet resistance reaches a minimum at approximately 300 LP, consistent with efficient chemical reduction and recovery of the conjugated carbon network. These results provide molecular-level guidelines for optimizing laser-induced GO reduction toward graphene-based transparent conductive layers.

Physchem doi: 10.3390/physchem6030051

Authors: Evdokia Gkagkari Michail Mouratidis Theodoros Damartzis Nikolaos I. Tsongidis Emmanouil Daskalos Charikleia A. Poravou George Karagiannakis George Skevis Evanthia Kostarellou Thomas Kaimakamis Marios Kyrkos Ananias Tomboulides Vasileios K. Michalis Nikolaos Pistofidis Vasileios Stroungaris Nikolaos Poulianas Ioannis N. Tsimpanogiannis Akrivi Asimakopoulou

The transition toward low-carbon cement production requires alternative fuels with improved environmental performance and resource efficiency. Refuse-Derived Fuel (RDF), produced from pre-treated non-recyclable waste streams, represents a promising alternative fuel; however, its heterogeneous and varying composition presents challenges for stable combustion and process optimization. In this study, a comprehensive physicochemical characterization of RDF was performed and compared with pet coke, a conventional, fossil cement kiln fuel. The analysis included manual sorting, particle size distribution, elemental characterization, Scanning Electron Microscopy coupled with Energy dispersive X-ray spectroscopy (SEM/EDS), X-ray Diffraction (XRD), thermogravimetric and differential scanning calorimetry (TGA/DSC), and Higher Heating Value (HHV) determination. The RDF sample exhibited a heterogeneous polymeric-mineral composition dominated by plastics, paper, textiles, and inorganic fractions. TGA revealed a broad multi-stage thermal degradation profile, while calorimetry indicated HHV of 19.2 ± 0.3 MJ/kg and ash content of 11.6 wt.%, compared with 34.57 ± 0.11 MJ/kg and 1.97 wt.% for pet coke, respectively. SEM/EDS and XRD analyses confirmed the coexistence of polymeric and mineral phases in RDF, whereas pet coke exhibited a predominantly carbonaceous and homogeneous composition. The generated dataset supports computational fluid dynamics (CFD)-based cement kiln combustion models and RDF utilization for fossil fuel substitution in the cement industry.

Physchem doi: 10.3390/physchem6030050

Authors: Solomon E. Shaibu Nathaniel S. Essien Idongesit B. Anweting Itoro E. Udo Eric S. Archibong Nnamso D. Ibuotenang Edu J. Inam Dele P. Fapojuwo Nsima A. Akpan Nnanake-Abasi O. Offiong

The increasing prevalence of heavy metal contamination in aqueous environments poses severe risks to both human health and the ecosystem. To address this environmental concern, this study focused on the utilization of a nature-based silver clay nanocomposite (NAgC) for the removal of cadmium (Cd(II)) and chromium (Cr(VI)) ions from aqueous media. The NAgC was synthesized through the reduction of silver ions in a clay matrix by employing the leaf of Manihot esculenta extract as the reducing agent. The NAgC was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), Brunauer, Emmett, and Teller (BET) surface area as well as energy-dispersive X-ray spectroscopy (EDX). The adsorption behavior of the NAgC in batch experiments under varying pH, contact time, initial concentration, and adsorbent dosage were investigated for the removal of cadmium and chromium from aqueous media. The optimum adsorption of cadmium ions was 157.87 mg/g, achieved at an initial concentration of 20 mg/L at 1 g dosage at pH 7 for 60 min, while that of chromium was 137.91 mg/g at a metal concentration of 20 mg/L at 1 g dosage at pH 7 for 60 min. The Freundlich isotherm model adequately explained the adsorption data of both Cd(II) and Cr(VI). However, the pseudo-first order (PFO) adequately interpreted the kinetic data for both Cd(II) and Cr(VI).

Physchem doi: 10.3390/physchem6030049

Authors: Manohar Aele Naveen Madamsetti Vikram Godishala Swati Dahariya Aditya Velidandi

Messenger RNA–lipid nanoparticles (mRNA-LNPs) have emerged as a transformative platform for nucleic acid therapeutics, yet their complex four-component lipid architecture comprising ionizable lipids, PEG–lipids, helper phospholipids, and cholesterol presents substantial analytical challenges for quality control and regulatory compliance. This review presents, for the first time, a critical evaluation of liquid chromatography–mass spectrometry (LC-MS) strategies specifically tailored to quantify all four lipid classes and their degradation products within mRNA-LNP formulations. Unlike prior general lipidomics reviews, we provide a comparative assessment of orthogonal LC modalities including reversed-phase ultra-high-performance liquid chromatography, hydrophilic-interaction liquid chromatography, ion-pairing reversed-phase LC, and high-performance liquid chromatography charged aerosol detection with explicit performance metrics (sensitivity, linearity, and run time). We further integrate emerging analytical frontiers—single-particle analysis, degradation product profiling (e.g., oxysterols and reactive electrophiles), and regulatory frameworks (ICH Q2(R1), Analytical Quality by Design)—to offer a practical guide for method selection. This review’s uniqueness lies in its systematic, application-focused comparison of LC-MS workflows addressing lipid-specific vulnerabilities, matrix effects, and stability-indicating parameters, filling a critical gap between analytical chemistry and mRNA-LNP product development.

Physchem doi: 10.3390/physchem6030048

Authors: Mahmoud AlGharram Tariq AlZoubi Ghaseb N. Makhadmeh Hani El Moll

Powder X-ray diffraction was used to validate the crystal structure of iron metal powder and to demonstrate a transparent workflow for extracting crystallographic and microstructural information from a simple laboratory dataset. The diffraction profile collected over the angular range of approximately 36° to 95° contains three dominant reflections located at 2θ = 44.850°, 65.218°, and 82.540°. Conversion of the peak positions into d-spacings using Bragg’s law gives values of approximately 2.020 Å, 1.430 Å, and 1.170 Å. The squared-sine ratios, when referenced to the first reflection, follow the sequence of 1:2:3, which is characteristic of the allowed reflections of a body-centered cubic lattice when multiplied by the first allowed value of N = h2 + k2 + l2 = 2. Therefore, the peaks are assigned to the (110), (200), and (211) reflections of α-Fe. The extracted lattice constants are 2.853, 2.860, and 2.865 Å, yielding an average value of 2.859 Å, which is close to the accepted room-temperature value of approximately 2.866 Å for α-Fe. Peak-width calculations based on the observed, instrument-uncorrected FWHM values are included only as illustrative apparent line-broadening indicators. Because an external instrumental standard was not measured under identical conditions, no quantitative coherent-domain size or microstrain is claimed. The Williamson–Hall treatment is therefore used only to demonstrate the sensitivity of size-strain interpretation to peak breadth, profile selection, and the limited number of available reflections. The intensity hierarchy was analyzed using the body-centered cubic-structure factor, reflection multiplicity, Fe atomic form factor, and Lorentz polarization correction. The comparison between calculated and experimental intensities shows stronger disagreement than the lattice-parameter analysis, illustrating the greater sensitivity of intensity analysis to preferred orientation, specimen preparation, peak-profile selection, and background treatment. The work provides a publication-style reconstruction of an iron powder XRD experiment, connecting peak fitting, indexing, lattice-parameter determination, crystallite size estimation, size-strain analysis, and intensity interpretation in a single critical framework.

Physchem doi: 10.3390/physchem6030047

Authors: Antonio de Nigris Mario Zeppa Luigi Ambrosone

Drug release from long-acting intravitreal implants is governed by the coupled effects of diffusion, hydrolysis-driven erosion, and progressive shrinkage of the polymeric matrix. To capture these mechanisms, we solve the diffusion equation in a cylindrical domain whose radius decreases according to the hydrolytic degradation kinetics of PLGA, which follow a pseudo-first-order behaviour in aqueous excess. The resulting formulation combines a modal Bessel expansion with an erosion-controlled time transformation, allowing the evolving geometry and the attenuation of the diffusion modes to be incorporated in a fully mechanistic manner. Within this framework, the shrinkage parameter p quantifies the rate of erosion-induced geometric evolution and enables an accurate reconstruction of the experimental dexamethasone release profile. The solution reproduces both the initial fast-release phase and the extended depletion tail from which the characteristic times t0.50=264.3h and t0.90=996.5h are extracted, providing compact and physically meaningful indicators of the transition between early and late kinetic regimes. Overall, the approach offers a robust and interpretable description of drug release from shrinking polymeric systems and is directly applicable to the design of long-acting intravitreal therapies.

Physchem doi: 10.3390/physchem6030046

Authors: Daniela Ž. Popović Teodora Adamović Jelena Miladinović Ferenc T. Pastor Mouad Arrad Zoran P. Miladinović

This study examines interactions in aqueous electrolyte solutions using the equations of the Scatchard and Friedman models. The six mixing parameters of the Scatchard model, bAB(01); bAB(02); bAB(03); bAB(12); bAB(13) and bAB(23), were obtained from the literature and estimated by processing experimental results measured by the isopiestic method for osmotic coefficients of three-component systems: {yKCl + (1 − y)K2HPO4} (aq), {yKBr + (1 − y)K2HPO4} (aq), {yKNO3 + (1 − y)K2HPO4} (aq), {yK2SO4 + (1 − y)K2HPO4} (aq), {yKH2PO4 + (1 − y)K2HPO4} (aq) and {yNaH2PO4 + (1 − y) K2HPO4} (aq) at 298.15 K. The Friedman parameters were calculated from the adopted Scatchard parameters as functions of ionic strength. The effects of pair, triplet, and quadruplet interactions on the excess Gibbs energy of mixing were analyzed, and the total Gibbs energy of the solutions was determined. In the systems {yKCl + (1 − y)K2HPO4} (aq), {yKBr + (1 − y)K2HPO4} (aq), {yKNO3 + (1 − y)K2HPO4} (aq), interactions between different anions of the same charge predominate. Triplet interactions dominate in the system {yK2SO4 + (1 − y)K2HPO4} (aq). The strongest contributions of triplet and quadruplet interactions are observed in the {yKH2PO4 + (1 − y)K2HPO4} (aq) system, whereas pair interactions between the same ion pairs are dominant in the {yNa2HPO4 + (1 − y)K2HPO4} (aq) system.

Physchem doi: 10.3390/physchem6030045

Authors: Shogo Ariizumi Christian Ebere Enyoh Tochukwu Oluwatosin Maduka Go Masuda Satoshi Anzai Miho Suzuki Qingyue Wang

Most research on Nanobubble Water (NBW) for lignocellulose conversion has focused on anaerobic digestion, with relatively few studies examining direct pretreatment methods such as liquefaction. In this study, we explored the potential of NBW as a pretreatment method for bagasse meal liquefaction. Bagasse meal was treated with oxygen, nitrogen, and carbon dioxide NBW. Changes in component composition ratio, crystallinity, total crystallinity index (TCI), lateral order index (LOI), pyrolysis peak temperature (Tmax), and apparent activation energy (Ea′) were investigated. For the liquefaction process, changes in residue content, apparent liquefaction reaction rate constant (k′), average molecular weight, hydroxyl value, functional group information, and Tmax of the liquefied residue were examined. Results showed a 2.0–3.0% decrease in cellulose and a 1.0–4.0% decrease in lignin. Crystallinity increased by 5.8–12%, TCI decreased by 6.7–13%, and LOI increased by 4.7–9.8%. Tmax decreased by 1.6–3.5 °C, and Ea′ decreased by 1.9–2.8%, both reaching their lowest values with carbon dioxide NBW. At this time, the residue content decreased by 6.3–19%, and k′ increased by 50%. These findings indicate that NBW pretreatment is a promising approach for liquefying bagasse meal under laboratory conditions. Future investigations will be directed towards its scalability and economic viability.

Physchem doi: 10.3390/physchem6030044

Authors: Qiang Tang Jau Tang

Propagation anisotropy in one-dimensional conductors is commonly interpreted within the framework of Tomonaga–Luttinger liquid theory, where electron–electron interactions lead to distinct channel-dependent excitation velocities. In this work, we investigate a complementary mechanism in which propagation anisotropy arises from structured substrate modulation. We develop a quantitative two-channel effective-medium transport model incorporating position-dependent dielectric and magnetic coupling terms within an effective spinor Hamiltonian. Under an adiabatic envelope approximation, the coupled spinor dynamics are reduced to an effective scalar propagation equation suitable for numerical simulation. The model predicts that spatial modulation of substrate response can generate measurable channel-dependent velocity splitting, wave-packet deformation, and propagation delay. Numerical simulations show that dielectric modulation, magnetic modulation, relative phase shifts, and moderate disorder influence transport anisotropy in distinct and tunable ways. For experimentally realistic parameter ranges, the predicted propagation delay lies in the picosecond regime over micrometer-scale transport distances. Comparison with conventional Tomonaga–Luttinger liquid theory suggests that substrate-induced effects may coexist with intrinsic many-body interactions and contribute appreciably to observed transport behavior. The proposed framework provides a quantitative phenomenological tool for analyzing substrate-controlled anisotropic transport and offers experimentally testable predictions for low-dimensional quantum systems.

Physchem doi: 10.3390/physchem6030043

Authors: Maria José V. Lourenço João F. Chainho Pedro C. Rodrigues Valentim B. Nunes Carlos A. Nieto de Castro

Molten salts are increasingly regarded as promising fluids for high-temperature heat transfer, thermal energy storage, and advanced reaction processes, including concentrated solar power (CSP), molten salt oxidation (MSO), and next-generation nuclear reactors. Among these materials, the ternary eutectic mixture Li2CO3–Na2CO3–K2CO3 (32.12–33.36–34.52 wt%) has emerged as a leading candidate due to its wide operating temperature range and favourable thermodynamic properties. Despite its relevance, substantial inconsistencies and gaps remain in the available thermophysical property data, posing challenges for reliable design, modelling, and industrial deployment. This work revisits the Li2CO3–Na2CO3–K2CO3 eutectic through a critical assessment of the literature from its reported melting point at 670 K (397 °C) up to approximately 1200 K (927 °C). Using a methodology inspired by IUPAC-supported strategies previously applied to common liquids such as water and hydrocarbons, we examine the quantity, quality, and coherence of existing measurements. Reference correlations are proposed only where the data are sufficiently robust to justify them. The analysis highlights a pressing need for more accurate and comprehensive measurements—particularly for heat capacity, thermal conductivity, and viscosity—to enable the development of reliable standard reference correlations. Brief recommendations are given on the measurement methods that should be used in high-temperature measurements, namely for heat capacity, viscosity, and thermal conductivity. Reliable thermophysical property data for (LiNaK)2CO3 remain limited and inconsistent, despite its relevance for high-temperature energy applications. Density data are comparatively robust, but heat capacity, thermal conductivity, and viscosity still require high-accuracy measurements at elevated temperatures. Addressing these data deficiencies is essential for advancing the safe and efficient use of molten carbonates in high-temperature energy technologies.

Physchem doi: 10.3390/physchem6030042

Authors: Aigerim Zhaxybayeva

Cucurbiturils (CB[n]) are rigid glycoluril-based macrocycles possessing well-defined hydrophobic cavities capable of forming stable host–guest complexes in water. Owing to these properties, CB[n]-containing supramolecular polymer gels have attracted increasing attention as functional composite materials in modern materials science. This review summarizes recent progress in the development of cucurbituril-based supramolecular gels, with particular attention to synthetic approaches, network design, and emerging applications. Both conventional acid-catalyzed methods and more sustainable synthetic strategies for cucurbituril preparation and functionalization are discussed. We further consider the role of CB[n] macrocycles as reversible crosslinking units in polymer networks and analyze how host–guest interactions influence the mechanical properties, self-healing behavior, and stimuli responsiveness of the resulting materials. Recent applications in biomedical engineering, soft electronics, and environmental remediation are also highlighted, demonstrating how molecular-level supramolecular interactions can determine the macroscopic performance of these composite systems. The review concludes with perspectives on scalable synthesis, processing integration, and future directions in supramolecular composite materials.

Physchem doi: 10.3390/physchem6030041

Authors: Guillermo Martínez-Cadena Brenda Isela Berrelleza-Félix Dolores Judith Caballero-Jiménez Diana Laura Villegas-Coronado Judith Celina Tánori-Córdova Amir Dario Maldonado-Arce Diana Vargas-Hernández

Dye removal from aqueous solutions remains a major global environmental challenge. Among the various remediation techniques, adsorption using natural materials has gained significant attention. In this study, the adsorption of methylene blue (MB) by a natural volcanic rock (VR) adsorbent—collected from the Cerro Blanco volcano in Divisaderos, Sonora, Mexico—was investigated, and the process efficiency was evaluated at different temperatures. The comprehensive characterization revealed a rough and irregular porous surface via SEM, while the EDS elemental data and the CIPW normative calculations identified the material as a silica-saturated tholeiitic basalt, primarily composed of bytownite (An71) and pyroxenes. This petrological classification was cross-validated by XRD and FTIR spectra, which exhibited vibrational modes characteristic of mafic silicate. The surface analysis via the BET method indicated a specific surface area of 12 m2·g−1, while a BJH analysis indicated a mesoporous structure (average pore diameter of 3.75 nm), and a Type IV isotherm with H3-type hysteresis, suggesting narrow, slit-shaped pores. Batch adsorption experiments demonstrated an exceptional removal efficiency of 99.99% for 50 mg·L−1 MB within only 30 min. The equilibrium data and the adsorption kinetics followed the Langmuir isotherm and a pseudo-second-order model, respectively. Cytotoxicity assays confirmed the VR is biosafe. The combination of high removal efficiency, low cost, and environmental safety positions this material as high-potential adsorbent for sustainable water remediation processes.

Physchem doi: 10.3390/physchem6030040

Authors: Yulong Lu Aiguo Feng Chunlin He Zezuo Jiang Shiqiang Wei Wenhan Sun Xinpeng Wang

A novel mesoporous XAD-based adsorbent (A336/XAD-7) was produced by impregnating the ionic liquid A336 into the pores of XAD-7 resin and used to separate tin(IV) and cadmium(II) from high-level liquid waste (HLLW). The as-produced material was characterized by SEM-EDS, TG-DSC, and N2 adsorption–desorption isotherms, which revealed a well-developed open pore structure, high loading capacity, and large specific surface area. Adsorption performance analysis showed that in 4 M HCl solution, the experimental saturated adsorption capacity qexp of A336/XAD-7 for Sn(IV) and Cd(II) were 39.51 mg/g and 34.18 mg/g, respectively, with equilibrium reached within 120 min. Among ten coexisting metal ions (Sn4+, Cd2+, Co2+, Ni2+, Cu2+, Eu3+, Y3+, Ca2+, Mg2+, Al3+) in HLLW, A336/XAD-7 exhibited excellent selectivity for Sn(IV) under high acidity, with a separation factor (SFSn/others) of 13.13. Column experiments further evaluated the dynamic separation of Sn(IV) from simulated HLLW using A336/XAD-7, achieving an enrichment factor greater than 7. XPS spectra indicated that the adsorption mechanism involved anion exchange between A336/XAD-7 and the complex anions SnCl62− and CdCl42−. This work demonstrates the application potential of A336/XAD-7 for HLLW treatment and provides valuable guidance for the efficient separation of other metal ions.

Physchem doi: 10.3390/physchem6030039

Authors: Luis Josimar Vences Reynoso Roberto Alejo Eleuterio Everardo Efrén Granda Gutiérrez Daniel Villanueva Vázquez Juan Horacio Pacheco Sánchez Allan A. Flores Fuentes Federico Del Razo López

Accurate estimation of molecule–nanotube interaction energies is critical for the computational screening of carbon-based materials for hydrogen storage; however, density functional theory (DFT) calculations remain computationally expensive for extensive configurational sampling. In this work, we develop a multilayer perceptron (MLP) surrogate model to predict H2–CNT interaction energies, represented by Eads, for H2 interactions with a chiral (2,1) carbon nanotube. A curated dataset comprising 696 configurations was generated using DMol3 (BIOVIA Materials Studio), varying intermolecular distance, molecular orientation, and interaction site across three regions: internal cavity, edges, and external surface. The proposed MLP architecture (64–32–1) incorporates GELU activation functions, L2 regularization, and dropout to improve generalization. The model achieves coefficients of determination in the range R2 = 0.90–0.96 across all interaction regions, with particularly strong performance at the nanotube edges (R2 = 0.9358, MSE = 0.046 eV2), as well as on the external surface (R2 = 0.9625, MSE = 0.574 eV2) and within the internal cavity (R2 = 0.9051, MSE = 1.506 eV2). The original Eads distribution had a mean of 4.0955 eV and a sample standard deviation of 4.3189 eV. The elevated energy values observed in the internal cavity (up to 12 eV) are consistent with steric repulsion induced by geometric confinement rather than predictive artifacts. The trained MLP showed close agreement with DFT-derived trends, enabling exploration of interaction-energy landscapes spanning both attractive and repulsive regimes. These results indicate that MLP-based models trained on diverse configurational datasets provide a computationally efficient alternative for screening carbon nanostructures in hydrogen storage applications, without substantially compromising accuracy relative to first-principles methods.

Physchem doi: 10.3390/physchem6030038

Authors: Maria Risva Alexandros Petrakis Angelos G. Kalampounias

In this work, an ultrasonic relaxation spectroscopic study of aqueous ammonium Fe(II) sulfate, aqueous ammonium Fe(III) sulfate and the corresponding ternary system has been undertaken. A variety of acoustic parameters including relaxation frequency, relaxation amplitude and speed of sound were determined as a function of solution concentration. In addition, the adiabatic compressibility and the molar volume change during the ionic association in ammonium Fe(II) sulfate and ammonium Fe(III) sulfate aqueous solutions were also estimated from the acoustic data. This approach facilitated a comprehensive characterization of the three systems across different concentrations. In the two binary systems, the presence of an ion association mechanism was identified involving the divalent and trivalent iron ions, with the sulfate anions, respectively. Furthermore, in the ternary system, an internal sphere oxidation–reduction mechanism occurred between the divalent and trivalent iron ions. All ions within each solution play an active role in shaping the structure of water molecules, owing to the prevailing kosmotropic characteristics specific to each solution. The results are examined within the context of the current phenomenological understanding in the field.

Physchem doi: 10.3390/physchem6020037

Authors: Yuri K. Altudov Adam M. Pshukov Aneta A. Kokoeva Nelli E. Pukhaeva Ntombizonke Y. Kheswa Vasily N. Kornoukhov

This work reports the colloidal synthesis of Nd-containing mixed-halide perovskite quantum dots described as CsPb(Nd)Br3−γClγ, followed by post-synthetic surface modification with an acid-activated amino-functional siloxane. This notation is used deliberately because the available FE-SEM, DLS, EDX, and optical data confirm the formation of an Nd-containing mixed-halide colloidal perovskite system, but do not provide direct crystallographic proof of substitutional Nd3+ incorporation at the Pb2+ B-site. The obtained dispersions show stable blue emission with a maximum at about 458 nm, a photoluminescence quantum yield of about 56%, an essentially invariant emission maximum when the excitation wavelength is varied from 300 to 390 nm, and monoexponential decay kinetics with a characteristic lifetime of 6.67 ± 0.97 ns. Field-emission scanning electron microscopy combined with morphometric analysis of at least 150 particles indicates a nanoscale size distribution with an average equivalent diameter of 8.8 nm, a median of 7.3 nm, and 93.25% of particles smaller than 25 nm. Dynamic light scattering confirms a narrow hydrodynamic size distribution in the 7–9 nm range and a low polydispersity index. Elemental mapping by EDX confirms the co-presence of Cs, Pb, Br, Cl, and Nd in the analyzed particles. The observed blue shift is discussed in terms of the combined effect of chloride incorporation, nanoscale size, possible Nd-related perturbation of the local electronic/defect structure, and reduced non-radiative losses after surface passivation. No definitive crystallographic assignment of Nd to a specific lattice site is claimed; the composition is therefore treated as nominal, and the structural interpretation remains provisional pending XRD/XPS or related studies.

Physchem doi: 10.3390/physchem6020036

Authors: Fathi Elashhab Lobna Sheha Nada Elzawi

Heparin is a highly sulphated polyelectrolyte, and its properties depend strongly on its shape in solution. In this study, we closely examined the structural behaviour of low-molecular-weight heparin under aerobic ultraviolet-C (UVC, 100–280 nm) radiation. Using controlled photodegradation, we prepared native, small, and ultra-small molar-mass fractions, enabling us to investigate how structural properties vary with molecular weight. We examined relationships among molar mass, radius of gyration, second virial coefficient, and critical overlap concentration to characterise different conformational states. Our results showed that as molar mass decreased, the chain diameter and persistence length also dropped, while the overlap concentration increased. This indicates a reduced hydrodynamic volume and increased chain flexibility. Positive second virial coefficient values indicate that polymer–solvent interactions remained favourable after photodegradation. The scaling exponents suggest that degraded heparin behaves as a semi-flexible polyelectrolyte and adopts an extended-coil shape in water with electrolytes. Further analysis showed that the characteristic ratio and chain stiffness decreased as chains were broken by irradiation. Overall, aerobic UVC irradiation provides a reliable way to modify the physical structure of these molecules while maintaining solution stability. These findings show a clear link between reduced molecular weight and changes in shape, which is useful for developing better low-molecular-weight heparins for several applications, including pharmaceutical and medical use.

Physchem doi: 10.3390/physchem6020035

Authors: Asparuh Markovski Lidia Zaharieva Vera Deneva Elena Taskova Tsanislava Genova Alexander Gegov Christina Andreeva Liudmil Antonov

The question of verification of food quality has stood before scientists since ancient times, and, nowadays, the advances in science and technology have made it a very challenging task. Laser-induced fluorescence (LIF) spectroscopy has become a very useful instrument for sample characterization. Nevertheless, analysis of complex multi-component spectra is difficult to approach. In recent years, the capabilities of artificial intelligence have attracted a lot of attention, as they open doors to efficient solutions of many problems that otherwise require a lot of time, effort, expenses and often inspiration. In the present work, we use LIF spectra of mixtures of sunflower and extra virgin olive oils with different concentrations and apply neural network (NN) algorithms with the aim of improving the strategies for concentration determination. Two different approaches have been applied and their output has been compared and commented. More specifically, the task of concentration recognition has been targeted as a classification and as a fitting problem. We formulate four diagnostic parameters with biochemical meaning and compare the NN performance when training with raw spectra and with the diagnostic parameters. The correct choice of appropriate diagnostic parameters is of importance from the point of view of biochemical interpretability and analysis, whereas “black box” full-spectra training might be beneficial for end-user applications. Our results show that these methods perform well even with very scarce data and outline preliminary strategies for defining diagnostic criteria.

Physchem doi: 10.3390/physchem6020034

Authors: Mihalj Poša

In physical chemistry textbooks, it is explained that thermodynamic processes in isolated systems (with constant internal energy) evolve until the total entropy reaches a maximum value; irreversible processes, or those in closed systems (at a constant entropy value of the system), evolve until the total internal energy reaches a minimum value; and in quasi-static processes, the maximum work is obtained under the given conditions. However, if the maximum useful work is not obtained from the system, the thermodynamic process is usually described using the Clausius inequality. Assuming that the internal energy and entropy are first-order homogeneous functions (according to Euler’s relation and additivity over system elements) and that they are state functions based on the principle of local equilibrium, the principle of maximum entropy and minimum internal energy can be applied not only to entire isolated or closed systems but to any volume element of the system. From this follows a unique discussion of the transition of a closed system (with a quasi-static isentropic process) to an isolated (irreversible) system, along with the thermodynamic process that occurs when the system remains closed and does not achieve the maximum useful work, some of which is dissipated.

Physchem doi: 10.3390/physchem6020033

Authors: Oscar Vieyra-Brito Estela Gómez-Barojas Enrique Quiroga-González

The present work represents a step forward in the production of a battery that can be recharged with light, without the need to integrate an energy generation device (e.g., a solar cell). Here, a silicon Li-ion battery electrode is reported, which has a current collector with an optical window that allows the impinging of light to it. The contact between the current collector and silicon is Schottky-type, behaving as a photodiode that injects charges into the electrode, which are added to the current applied to it when it is charged. The electrode presented in the present work is a proof of concept, with one of the simplest possible structures that the electrode could have to be functional (an optimized microstuctured electrode with improved charge/discharge cycling stability is envisioned): the electrode consists of monolithic silicon that has been microstructured in the backside by metal assisted chemical etching and has been decorated with Cu particles that work as a current collector. I-V curves show that the electrode by itself functions as a Schottky-type photodiode. On the other hand, when the chip is used as an electrode of a Li-ion battery, it can be properly lithiated/delithiated (it is a rechargeable electrode). Furthermore, it has been proven that when lithiation has been performed, this process has been enhanced by applying light to the current collector.

Physchem doi: 10.3390/physchem6020031

Authors: Nina Jusnita Nancy Dewi Yuliana Kenza Benkaid Sugiyono Liu Fei Ahmed Tara Nugraha Edhi Suyatma

The growing demand for sustainable smart packaging arises from the urgent need to preserve food quality and minimize environmental waste. In this study, multifunctional gelatin-based pH-responsive indicator films were fabricated by incorporating anthocyanins extracted from Hibiscus x archeri W Watson (HAE) and zinc oxide nanoparticles (ZnO-NPs). The incorporation of HAE and ZnO-NPs enhanced surface hydrophobicity, as evidenced by an increase in the water contact angle from 99° to 106°. The Fourier transform infrared (FTIR) analysis verified the lack of new chemical bond formation, indicating that the interactions among components were primarily physical in nature. Distinct colour transitions in buffer solutions of differing pH demonstrated the films’ colorimetric behavior. The films exhibited strong antimicrobial activity against Listeria monocytogenes (18.961 mm), Salmonella typhimurium (18.969 mm), and Aeromonas hydrophila (18.237 mm), whereas the neat gelatin film showed no inhibitory zone. The films also demonstrated superior UV-blocking capacity, with an opacity value (1.34 a.u/mm) compared to the control gelatin film (0.79 a.u/mm). Notably, fish fillets wrapped with the films remained fresh for up to 10 days, compared to day 4 for the unwrapped samples. These findings highlight the considerable potential of multifunctional, active and intelligent packaging for food preservation and real-time freshness monitoring.

Physchem doi: 10.3390/physchem6020032

Authors: Rashed Kaiser Aliyu Aliyu Ilyasu Anda

Hydrogen energy systems rely extensively on polymeric materials for storage, sealing, transport, and tribological applications; however, their long-term reliability is strongly influenced by hydrogen–polymer interactions. This review presents a comparative analysis of polymers with and without hydrogen bonding, focusing on how molecular architecture governs hydrogen compatibility, transport behavior, and degradation mechanisms under high-pressure environments. Hydrogen-bonded polymers, such as polyamides, polyurethanes (PU), and polyimides, exhibit high mechanical strength and thermal stability due to strong intermolecular interactions but are susceptible to hydrogen-assisted chemical degradation and embrittlement. In contrast, non-hydrogen-bonded polymers, including polyethylene, polypropylene (PP), polytetrafluoroethylene (PTFE), and Polyether ether ketone (PEEK), demonstrate excellent chemical inertness and low hydrogen reactivity, yet experience diffusion-driven damage such as blistering and fatigue softening. This study establishes a unified framework linking molecular structure, hydrogen transport, and failure mechanisms, revealing a fundamental trade-off between mechanical integrity and chemical stability. Advanced strategies, including polymer blending, nanofiller reinforcement, and multilayer composites, are proposed to optimize durability, permeability, and overall hydrogen compatibility.

Physchem doi: 10.3390/physchem6020030

Authors: Maria-Tereza Siavou Panagiotis Liakos Alexandros Ioannidis Evangelos Kyrilas Niki Sorogas Anna Marinopoulou Andreana N. Assimopoulou Olga Karabinaki Dimitrios Christofilos John Arvanitidis

The high pressure response and structural stability of crystalline racemic (RS) ibuprofen up to 7 GPa are explored by Raman spectroscopy, employing diamond anvil cells for the pressure application and glycerol as the pressure transmitting medium. Two independent high pressure experiments were performed with practically identical results. Both intermolecular vibrations (associated with weak van der Waals interactions and hydrogen bonding between ibuprofen molecules) and intramolecular vibrations (associated with strong covalent bonding within the ibuprofen molecule) are monitored as a function of pressure, with the former being far more susceptible to volume contraction. The pressure dependence of the Raman peak frequencies undergoes two distinct changes at ~2 and ~6 GPa, indicating the occurrence of pressure-induced structural modifications of ibuprofen. Based on the high pressure Raman data for the intermolecular vibrations of the RS ibuprofen below 2 GPa, a zero pressure value for the bulk modulus of ~7.5 GPa is also extracted.

Physchem doi: 10.3390/physchem6020029

Authors: Tochukwu Oluwatosin Maduka Qingyue Wang Christian Ebere Enyoh

The interaction between airborne allergens and environmental microplastics is an emerging concern in the context of increasing plastic pollution and allergic disease prevalence. In this study, we investigated the molecular interaction between Cry j 1, the major allergen of Japanese cedar (Cryptomeria japonica) pollen, and polyethylene terephthalate (PET) microplastic surfaces using all-atom molecular dynamics simulations integrated with computational epitope selection analyses. The simulations showed that Cry j 1 adsorbs onto PET primarily through hydrophobic and van der Waals interactions, with residues Pro165, Ala227, Tyr228, and Val163 contributing prominently to surface association. Mapping of selected epitope regions indicated that several linear B-cell epitopes remained solvent exposed following adsorption, whereas two CD4+ T-cell epitope regions (T5 and T6) contributed more directly to PET interaction. PET adsorption was accompanied by moderate changes in conformational dynamics, including reduced residue-level flexibility and localized secondary-structure adjustments, while the overall protein fold remained structurally stable throughout the simulation. Small decreases in radius of gyration and solvent-accessible surface area suggested mild adsorption-associated compaction rather than major unfolding. These findings indicate that PET association can influence the structural dynamics and interfacial behavior of Cry j 1 without extensive disruption of its global architecture. Because the study is entirely computational, the immunological implications remain hypothetical and require experimental validation. Nevertheless, this work provides a molecular-level framework for understanding how airborne microplastics may influence allergen behavior and protein-surface interactions in polluted atmospheric environments.

Physchem doi: 10.3390/physchem6020028

Authors: Houda Foulah Anas Krime Soumia Aboulhrouz Naoual Ouchitachne Elisabete P. Carreiro Mina Oumam

Given the depletion of conventional oil and gas resources, oil shale represents a promising alternative source of hydrocarbons that can be recovered through pyrolysis. This study examines the thermal decomposition of raw oil shale from the Tarfaya deposit and its decarbonized concentrate, studied by thermogravimetric analysis at different heating rates (5, 10, 20 and 40 °C/min). Pretreatment with acetic acid enabled the selective removal of calcite, confirmed by elemental, XRF, and XRD analyses, which revealed a relative enrichment in silica and dolomite in the oil shale concentrate. Pyrolysis of the raw shale occurs primarily between 300 and 500 °C, with a conversion rate of approximately 30%. In contrast, for the oil shale concentrate, the pyrolysis process begins at a relatively low temperature, within a wider temperature range (260–520 °C). Kinetic analysis based on Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods shows that at a conversion rate of 60%, the activation energy achieves 14.09 kJ/mol and 10.78 kJ/mol, respectively. The results indicate that the selective removal of calcite by acetic acid treatment facilitates kerogen pyrolysis by reducing mineral–organic interactions. Indeed, calcite dilutes the reactive organic fraction and can act as a physical barrier limiting heat and mass transfer within the oil shale. Its removal improves, on the one hand, the accessibility of kerogen to thermal cracking and promotes its decomposition, and on the other hand, reduces the amount of residue after pyrolysis. In addition, the kinetic analysis based on Criado master curves reveals changes in the reaction mechanism after decarbonation treatment depending on the heating rate (β). A shift from a two-dimensional Avrami–Erofeev model (A2) to a three-dimensional model (A3) was observed at a low heating rate (β = 5 °C/min), suggesting a change in nucleation and growth dynamics during kerogen decomposition. At high heating rates (10, 20 and 40 °C/min), the thermal decomposition of kerogen combines several reaction mechanisms depending on the temperature range considered.

Physchem doi: 10.3390/physchem6020027

Authors: Jingchun Sun Linbing Zhang David Gonçalves Shaoping Kuang Hongsheng Yang

Glyphosate is a highly polar herbicide, the reliable molecular recognition of which is complicated by co-occurring structural analogues, metabolites, and derivatives in real-world samples. Rather than reporting new aptamer discovery, this study establishes a standardized, solution-phase isothermal titration calorimetry (ITC) workflow to thermodynamically reassess two literature-reported glyphosate DNA aptamers, Seq03 and Seq05, under matched buffer composition and instrument settings. After verification of baseline stability and evaluation of heat-of-dilution contributions, ligand-to-aptamer titrations yielded apparent dissociation constants of approximately 8.14 μM for Seq03 and 40.2 μM for Seq05, enabling affinity-based prioritization of these reported candidates within the tested concentration window. To define an application-relevant selectivity boundary, we further constructed a counter-screen panel restricted to glyphosate-related chemicals, including structural analogues, metabolites, and derivatives, and evaluated all candidates using an identical ITC protocol with explicit background handling. None of the counter-screen compounds produced binding-consistent, saturable isotherms after integration and control-based interpretation; instead, their responses remained close to background heat and were therefore operationally classified as having no detectable binding under the tested conditions, including a reverse-titration format check with Glufosinate-N-acetyl. Collectively, these results position ITC as a label-free, platform-independent validation step for small-molecule aptamer benchmarking prior to analytical translation, while also highlighting that the present conclusions are bounded by the tested PBS-based conditions and the sensitivity window of the current ITC configuration.

Physchem doi: 10.3390/physchem6020026

Authors: Inês Praça Cátia Guarda João Caseiro Ana Pires Victor Neto

The widespread adoption of additive manufacturing, particularly selective laser sintering (SLS), has raised concerns about the disposal of unused thermoplastic powder residues, such as polyamide 12 (PA12). The high cost of PA12 and its degradation during the SLS process highlight the need for sustainable reuse strategies. This study evaluates the feasibility of reprocessing non-sintered PA12 powder without the addition of virgin material through fused deposition modeling (FDM) and injection molding (IM). Thermal analysis showed that the material retains processing temperatures comparable to virgin PA12. However, a significant reduction in melt flow index (≈61%) was observed, reflecting reduced processability and suggesting molecular-level changes affecting chain mobility. Injection molding demonstrated consistent mechanical behavior and good ductility, confirming its suitability for processing recycled PA12. In contrast, FDM processing resulted in higher variability and reduced ductility, mainly due to limitations in interlayer bonding associated with the increased viscosity of the material. Overall, the results highlight injection molding as a robust route for the valorization of non-sintered PA12, while FDM remains a feasible but less reliable alternative requiring further optimization.

Physchem doi: 10.3390/physchem6020025

Authors: Rajeev Kumar Lalit Garia Chang-Won Yoon Mangal Sain

This study uses a bismuth ferrite (BiFeO3) and MXene (Ti3C2Tx) to design a surface plasmon resonance (SPR) biosensor for the sensitivity enhancement at a 633 nm wavelength. Here, MXene serves as a biorecognition element (BRE) layer to ensure stable and reliable biomolecule adsorption. The MXene is a family of two-dimensional (2D) materials with metallic-like conductivity, a large surface area that can attach biomolecules, and improve biocompatibility. The addition of a conductive 2D MXene layer and a high-index BiFeO3 dielectric layer greatly improves light–matter interaction and evanescent field penetration at the sensing interface. Strong plasmonic coupling is indicated by the reflectance analysis, which shows a distinct and consistent shift in the resonance angle as analyte RI increases. This study examined the sensitivity at optimized Ag and BiFeO3 layer thickness. At an Ag of 39 nm and BiFeO3 of 3 nm thickness, the maximal sensitivity of 340.68°/RIU with a remarkable figure of merit (FoM) of 47.38/RIU is obtained. The overall detection accuracy (DA) and FoM are significantly improved by the large sensitivity enhancement, despite a slight increase in full width at half maximum (FWHM). Furthermore, the penetration depth (PD) of 198.50 nm (at RI:1.330) and 199.52 nm (at RI:1.335) is attained with the proposed structure. Due to its high sensitivity, reusability, and reproducibility, the SPR biosensor has the potential to be used in biochemical, environmental, and medical detection.

Physchem doi: 10.3390/physchem6020024

Authors: Héctor Herrera Hernández Jorge A. Galaviz-Pérez María Guadalupe Hernández Cruz Jorge Morales Hernández Héctor J. Dorantes Rosales J. J. A. Flores Cuautle G. Lara Hernández Manuela Díaz Cruz

This study reports that titanium nanoparticles can be used as a surface coating to enhance the corrosion resistance of 316 stainless steel. It specifically examines the influence of the deposition temperature (Tdep) on the coating’s structural and morphological properties, including corrosion behavior. TiO2 nanoparticles were thoughtfully deposited on steel substrates at temperatures of 300, 400, and 500 °C using a horizontal hot-wall tubular reactor. This equipment was expertly engineered at the CIDETEQ laboratory through the metal–organic chemical vapor deposition (MOCVD) concept. Titanium isopropoxide [Ti(OC3H7)4] was used as the precursor for the coating synthesis. Structural analysis was conducted using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM). Corrosion performance was evaluated under accelerated conditions in 0.5 M H2SO4 using potentiodynamic anodic polarization (AP), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The corrosion test indicates that increasing Tdep significantly differentiates the coating morphology and improves corrosion resistance. AP revealed that the pitting potential (Epit) shifted to more positive values, ranging from +1.4 to +1.5 V. CV voltammograms indicated that coated samples had lower passive current densities (Ip ≈ 104 to 105 A/cm2) than the bare substrate. EIS analysis demonstrated that the coating deposited at 500 °C processed the most favorable electrochemical performance, resisting corrosion for over 28 days. This coating achieved the highest electrical resistance (297 kΩ·cm2) and the lowest capacitance (2.7 μF/cm2), attributed to the formation of a crystalline anatase phase composed of pyramidal-like nanoparticle agglomerates (~40 nm). The dense packing structure effectively blocks charge-transfer pathways, restricting electron and ion transfer. Finally, MOCVD-based chemical surface modification with TiO2 nanoparticles is considered an innovative method to improve the corrosion resistance of stainless steel, thereby prolonging its durability under accelerated sulfuric acid exposure.

Physchem doi: 10.3390/physchem6020023

Authors: Haradhan Kolya

Polymer–graphene composites have emerged as an advantageous class of functional materials that combine the exceptional electrical, mechanical, and surface properties of graphene with the ability to be processed, modified, and made more flexible through polymers. Polymer–graphene composites have recently seen rapid growth in environmental applications, including water treatment, pollutant degradation, sensing, and energy–environment interfaces. This review critically examines recent advancements in polymer–graphene composites for catalysis (including photocatalysis, electrocatalysis, hydrogenation, and energy conversion) and environmental applications (such as water treatment, dye degradation, heavy-metal removal, and oil–water separation). There is considerable discussion about structure–property–performance relationships, catalytic and adsorption mechanisms, and the role of polymer matrices. Current challenges, scalability issues, and future research directions for sustainable, industrially viable polymer–graphene systems are highlighted.

Physchem doi: 10.3390/physchem6020022

Authors: Saideep Mallepaka Himabindu Kurra Aditya Velidandi Pradeep Kumar Gandam Swati Dahariya Vikram Godishala

This study presents a statistically optimized protocol for the green synthesis of gold nanoparticles (Au NPs) using aqueous Kalanchoe pinnata leaf extract (AKPLE). An integrated experimental strategy, transitioning from preliminary one-factor-at-a-time (OFAT) screening to a five-factor Box–Behnken Design, was employed to model and simultaneously optimize two critical optical responses derived from surface plasmon resonance: the peak position (λmax) and its absorbance intensity. Highly predictive quadratic models (R2 > 0.97) revealed that synthesis outcomes are governed by significant nonlinear curvature, with minimal interaction effects. Multi-response optimization via a desirability function identified a harmonized set of conditions (HAuCl4: 0.44 mM, AKPLE: 3.50% v/v, temperature: 80.6 °C, pH: 7.2, time: 66.7 min) predicted to minimize λmax at 540 nm while maximizing absorbance to 0.61. Synthesis under these optimized conditions successfully produced spherical, crystalline Au NPs, as confirmed by characterization (average TEM size: 26.3 ± 4.1 nm; zeta potential: –30.45 mV). This work demonstrates that a hybrid OFAT-RSM approach is superior for the precise, multivariate optimization of plant-mediated Au NP synthesis, providing a validated and scalable framework to balance nanoparticle size and plasmonic intensity—an outcome unattainable through conventional OFAT methods.

Physchem doi: 10.3390/physchem6020021

Authors: Ayoub Koufi Younes Ziat Hamza Belkhanchi Charaf Laghlimi Noureddine Lakouari Zakaryaa Zarhri

This study provides a theoretical assessment of the structural, electronic, and thermal properties of MgMH3 (M = Mn and Ni) compounds using the full-potential linearized augmented plane wave (FP-LAPW) method, with a range of modern functionals. The thermoelectric properties that are surveyed here relate to the power factor, the dimensionless thermoelectric figure of merit, the thermal conductivity, and the electrical conductivity that are associated with these compounds. The study finds that MgNiH3 has superior thermoelectric properties compared to MgMnH3. The analysis of the band structure reveals that both materials conduct electricity like metals, as there is no energy gap (0 eV), indicating that the conduction and valence bands overlap. The thermal conductivity was found to be linearly related to an increase in temperature, whereas the electrical conductivity varied with temperature. At elevated temperatures, the maximum power factor values reach 1.45 × 10−3 W/(K2.m) for MgMnH3 and 1.96 × 10−3 W/(K2.m) for MgNiH3 at 900 K. Upon examination of the electronic states, the contributions to the metallic nature of these hydrides come largely from the Ni and Mn orbitals. This type of prospective information on the potential of MgNiH3 and MgMnH3 in industrial applications, especially thermoelectric applications, is a valuable contribution. Understanding their thermal and electronic structure will demonstrate their potential for industry.

Physchem doi: 10.3390/physchem6020020

Authors: Luis Castillo-Henríquez Pablo Agüero-Hidalgo Juan Miguel Zúñiga-Umaña Gabriela Montes de Oca-Vásquez Fátima Arce-Vásquez Zacarías Pereira-Vega Badr Bahloul Yohann Corvis José Roberto Vega-Baudrit

Green-synthesized silver nanoparticles (AgNPs) exhibit outstanding antibacterial and antioxidant potential for designing and developing nanomedicines and medical devices. Nephelium lappaceum or rambutan contains polyphenol-based phytochemicals, which suggests its suitability for the green synthesis of NPs. However, the lack of a systematic approach directly impacts the robustness and reproducibility of the process. Design of experiments can address these challenges in obtaining NPs with the desired quality profile. In this work, we demonstrated the advantages of a Plackett–Burman model in the semi-automated green synthesis of AgNPs using N. lappaceum peel extract. The extract concentration was the only significant factor affecting the particle size. The optimized NPs exhibited triangular and hexagonal morphologies and a hydrodynamic diameter of 80 nm after 24 h without a stabilizing agent, representing 1.2% prediction error according to the model’s equation. The in vitro antioxidant capacity was confirmed through the ABTS radical scavenging assay. The AgNPs displayed a minimum inhibitory concentration of 23.5 µg mL−1 against Escherichia coli and Staphylococcus aureus. Overall, this work highlights the synergistic role between a DoE-assisted green synthesis, the phytochemicals from N. lappaceum peel extract, and the formed AgNPs, positioning this systematic approach as a sustainable and efficient process for novel antibacterial and antioxidant agents.

Physchem doi: 10.3390/physchem6020019

Authors: Hind A. Satar Emad Yousif Ahmed Ahmed Dina S. Ahmed Mohammed Kadhom Mohammed H. Al-Mashhadani Muna Bufaroosha Tayser S. Gaaz Mohammed S. S. Alyami Sohad A. Alshareef Raghda Alsayed

This study reports the synthesis and evaluation of diclofenac-derived organotin(IV) complexes as photostabilizing additives for poly(vinyl chloride) (PVC). Diclofenac was selected as a ligand due to its aromatic structure and heteroatom-rich framework, enabling the formation of stable tin-based complexes with potential UV-absorbing and radical-scavenging properties. The synthesized di- and tri-organotin complexes were incorporated into PVC films at 0.5 wt.% and exposed to UV irradiation (365 nm) for up to 300 h to assess their stabilizing efficiency. Photodegradation was monitored by tracking changes in carbonyl, polyene, and hydroxyl indices, as well as weight loss and surface deterioration. Compared with blank PVC and ligand-containing films, the organotin-modified samples exhibited significantly slower growth of degradation indices, reduced mass loss, and improved surface integrity after irradiation. Among the evaluated additives, the tributyltin complex demonstrated the highest photostabilizing performance, showing superior retention of chlorine content and lower surface roughness parameters. Overall, the results indicate that diclofenac-based organotin(IV) complexes are effective photostabilizers for PVC, with the tributyltin derivative emerging as the most promising candidate for enhancing the durability of PVC materials under UV exposure.

Physchem doi: 10.3390/physchem6020018

Authors: Boyuan Cao Chen Sun Xiaofei Xing Zhao Zhang Mingxing Wei Chong Cui Yanghui Lu Wei Zheng Liangliang Lv Tong Liu

Efficient hydrogen separation and purification technology plays a crucial role in the hydrogen energy industry. VB-group alloy membranes have demonstrated favorable hydrogen permeability, but their hydrogen embrittlement resistance remains generally insufficient. This work designed Nb35Hf30Co15Ni20-xMox high-entropy alloy (HEA) membranes with regulated Ni and Mo contents. The influences of HEA compositions on microstructures, hydrogen permeability and hydrogen embrittlement resistance were systematically analyzed. On the one hand, the doping of Mo increased the volume and proportion of BCC-Nb phase, thus promoting hydrogen permeation; on the other hand, the hydrogen solubility was reduced, thus enhancing the hydrogen embrittlement resistance. The lattice distortion effect, sluggish diffusion effect and optimized Mo content collectively enhanced the comprehensive performance of Nb35Hf30Co15Ni12.5Mo7.5, achieving a hydrogen permeability (Φ) of 2.68 × 10−8 mol H2 m−1·s−1·Pa−0.5 at 673 K and exhibiting excellent hydrogen embrittlement resistance, showing no hydrogen-induced fractures even at room temperature. This quantitatively demonstrates its excellent performance, which represents a certain breakthrough compared to related studies. The novel Nb35Hf30Co15Ni20-xMox HEA membranes offer excellent hydrogen permeability and improved hydrogen embrittlement resistance, thereby highlighting the potential for future hydrogen purification applications.

Physchem doi: 10.3390/physchem6010017

Authors: Inês Mendes Lara Marques Eduarda Ribeiro Nuno Vale

Background: Clotrimazole (CLZ) is an approved antifungal with reported pleiotropic effects. Beyond its antifungal use, CLZ can perturb glycolytic flux and ionic homeostasis, motivating its evaluation as a repurposing candidate in oncology. Objective: We aimed to evaluate CLZ and nitazoxanide (NTZ) as drug repurposing candidates for pancreatic ductal adenocarcinoma (PDAC) in comparison with standard chemotherapeutics gemcitabine (GEM) and 5-fluorouracil (5-FU). Methods: T3M4 PDAC cells were treated (0.1–100 µM; 48–72 h) with 5-FU, GEM, CLZ, and NTZ. Cell viability (MTT) and morphology were assessed, and CLZ-based combinations were analyzed by the Chou–Talalay method. In silico studies provided physicochemical descriptors and ADMET profiles, along with predicted interactions with relevant bioorganic targets (e.g., KCa3.1/KCNN4 ion channels). Results: CLZ produced marked cytotoxicity at 72 h (IC50 ≈ 9 µM) and achieved a greater reduction in cell viability at higher concentrations compared to 5-FU and GEM under identical conditions, whereas NTZ showed modest and inconsistent effects. CLZ combinations with 5-FU or GEM were mainly antagonistic. In silico analyses indicated high membrane permeability and suggested potential interactions with KCa3.1, supporting a hypothesis-generating interpretation of the observed in vitro effects. Conclusions: Within a drug repurposing framework, CLZ exhibited consistent cytotoxic activity as a single agent in a PDAC cell model, whereas NTZ revealed limited effects and CLZ-based combinations were not beneficial under the tested conditions. These findings position CLZ as a monotherapy-oriented repurposing candidate for PDAC and motivate further mechanistic and translational studies to clarify the biological basis of its in vitro activity.

Physchem doi: 10.3390/physchem6010016

Authors: Everton Crestani Rambo Ana Clarissa Kolbow Sankler Soares de Sá Romildo Jerônimo Ramos Alexandre Marletta Eralci Moreira Therézio

In this work, poly(3-dodecylthiophene) (P3DDT) thin films were electrochemically synthesized onto fluorine-doped tin oxide (FTO) substrates via cyclic voltammetry using tetraethylammonium tetrafluoroborate (Et4NBF4) as the supporting electrolyte. Optical analyses were performed using ultraviolet–visible absorption spectroscopy (UV-Vis), photoluminescence spectroscopy (PL), emission ellipsometry (EE) and Raman spectroscopy. The results revealed the formation of distinct structures during the electropolymerization process, which significantly affected the optical behavior observed in the UV–Vis and PL spectra. Furthermore, the EE measurements provided insights into the impact of these structures on the polarization states of emitted and transmitted light on energy and charge transfer mechanisms and on the photophysical behavior of P3DDT. Variations in the degree of polarization (P), anisotropy factor (r), and asymmetry factor (g) were analyzed as a function of the emission wavelength. The results confirm the potential of P3DDT as an active layer in electroluminescent devices, as the emissive material used in the active layer consisted exclusively of this polymer.

Physchem doi: 10.3390/physchem6010015

Authors: Ahmad Adlie Shamsuri Siti Nurul Ain Md. Jamil

Polymer blends are an essential category of materials formed by physically combining two or more polymers. The plasticizing process is advantageous for brittle or rigid polymer systems that need improved flexibility or ductility. The increasing demand for environmentally friendly and high-performance polymeric materials has spurred research into alternative plasticization methods. The use of ionic liquids as non-volatile plasticizers in polymer blends is owing to their outstanding properties. In this short review, several ionic liquids employed in polymer blends and some polymers used in blends with ionic liquids are listed. Additionally, the plasticizing effects of ionic liquids on the properties of polymer blends are concisely elucidated. This review also provides a brief overview of the potential applications of polymer blends plasticized with ionic liquids. In summary, many studies reveal that ionic liquid-based plasticization impacts the structural, thermal, conductive, and mechanical properties of polymer blends. The potential applications of polymer blends plasticized with ionic liquids cover various fields, including energy systems, packaging, electronics, and soft robotics.

Physchem doi: 10.3390/physchem6010014

Authors: Hayata Shirai Norihisa Kobayashi Kazuki Nakamura

Structural coloration has attracted significant attention as a concept for next-generation reflective displays and optical devices. It enables high optical stability and durability, appearing vivid and highly visible compared to conventional light-absorption systems. We present a novel hybrid light-reflecting device that integrates electrochromic materials with structural coloration to dynamically and reversibly modulate the reflected light. Experiments confirm that the electrochromic materials enable color modulation through redox reactions under an applied voltage, whereas photonic structures provide vivid, angle-dependent structural coloration based on interference or diffraction effects. The developed device can achieve multistage visual modulation by integrating structural coloration with electrochromic functionality. Further, by combining these two light-modulating mechanisms, our device offers enhanced functionality compared with conventional reflective systems.

Physchem doi: 10.3390/physchem6010013

Authors: Arata Suzuki Ziying Li Norihisa Kobayashi Kazuki Nakamura

The optical and thermal behaviors of a chiral europium(III) β-diketonate complex, Eu(D-facam)3 (facam: 3-(trifluoromethylhydroxymethylene)-(+)-camphorate), were examined in the presence of imidazolium-based ionic liquid 1-ethyl-3-methylimidazolium acetate (EMImOAc). The addition of EMImOAc to Eu(D-facam)3 butanol solutions enhanced their luminescence intensity by up to 74-fold and induced clear circularly polarized luminescence (gCPL = −0.28 for the 5D0 → 7F1 transition). When Eu(D-facam)3 was dissolved directly in EMImOAc, the Eu(III) complex also exhibited distinct circularly polarized luminescence (gCPL = −0.22). In addition, compared with the thermal stability of luminescence in 1-butanol, the ionic liquid solution exhibited superior thermal robustness, retaining approximately 30% of its room-temperature emission intensity even at 100 °C. Arrhenius analysis of the solutions was performed using their emission intensity and lifetime to evaluate the emission stability at higher-temperature regions near 70–100 °C. In EMImOAc, the thermal acceleration of the nonradiative decay of the ligands was suppressed; thus, the energy transfer from the ligand to the Eu(III) ion was stabilized even at higher temperatures. These results highlight the role of ionic liquids as effective media toward achieving thermally robust and highly emissive chiral Eu(III) systems.

Physchem doi: 10.3390/physchem6010012

Authors: Mohamed el A. Kramdi Aral Karahan Takeshi Watanabe Hidehiro Sekimoto Simon Desbief Gilles Quéléver Olivier Margeat Jörg Ackermann Carmen M. Ruiz Herrero Christine Videlot-Ackermann

Focusing on PM6 as the electron-donating polymer and the non-fullerene acceptors Y12 and PY-IT, this study investigates their chemical, optical, and morphological properties, as well as their compatibility in bulk heterojunction (BHJ) architectures. All materials were characterized in thin-film form using Fourier transform infrared (FTIR), and Raman spectroscopy. Binary blends of PM6:Y12 and PM6:PY-IT, along with the ternary PM6:PY-IT:Y12 system, were dissolved in o-xylene and processed into active layers by blade coating under ambient conditions. Optical properties were analyzed in solution and in thin films, providing insights into light-absorption efficiency and spectral complementarity. Nanoscale morphology and molecular packing were examined using atomic force microscopy (AFM) and grazing-incidence wide-angle X-ray scattering (GIWAXS), revealing correlations between material organization and device performance. The results highlight the importance of optimizing material selection, ink formulation, and film morphology to maximize charge-generation efficiency. Power-conversion efficiencies (PCEs) of 13.95%, 12.04%, and 12.17% were achieved for PM6:Y12, PM6:PY-IT, and PM6:PY-IT:Y12 devices, respectively. The ternary PM6:PY-IT:Y12 system demonstrated performance comparable to PM6:PY-IT, with improved miscibility and nearly aggregate-free morphologies, suggesting potential for further efficiency gains. These findings offer valuable guidance for designing high-performance, sustainable active layers, contributing to the development of next-generation organic photovoltaic technologies.

Physchem doi: 10.3390/physchem6010011

Authors: Raşit Dağlı Murat Teker Ayşe Usluoğlu

This study investigates the acid dyeing of Polyamide 6 (PA6) fabric by comparing conventional heating and microwave-assisted techniques. The influence of critical process parameters—namely pH, temperature, dyeing time, and dye concentration—on color strength (K/S) was systematically evaluated using C.I. Acid Blue 324. Results indicated an inverse correlation between pH and K/S for both methods, with the maximum color yield achieved at pH 3.0. While dye uptake improved with increasing temperature, time, and concentration in both systems, the microwave-assisted approach (160 W) significantly accelerated the process. Optimal conditions for conventional dyeing were established at pH 3, 95 °C, and a 30 min reaction time with 1.5% dye concentration. In contrast, the microwave-assisted process reached equivalent exhaustion levels in only 10 min under otherwise identical conditions. The findings confirm that microwave-assisted dyeing is a rapid, energy-efficient, and sustainable alternative for PA6 processing, offering substantial reductions in production time.

Physchem doi: 10.3390/physchem6010010

Authors: Evanthia Kostarellou Evdokia Gkagkari Michail Mouratidis Theodoros Damartzis George Skevis Alexandros Katsinos Thomas Kaimakamis Ananias Tomboulides Vasileios K. Michalis Vasileios Stroungaris Nikolaos Poulianas Marios S. Katsiotis Akrivi Asimakopoulou Ioannis N. Tsimpanogiannis

One thermodynamic parameter that is crucial to heat transport within the fluidized bed inside the rotary kiln, during clinker production, is the specific heat capacity. The particular parameter is often considered constant in the open literature, while, in reality, it strongly depends on the fluidized bed’s temperature and composition, considering that the temperature inside the kiln ranges from approx. 800 K up to 2000 K. For the current study, a mixing rule reported in the literature was applied in order to calculate the Cp of the fluidized bed, utilizing temperature and composition profiles available in the literature. An in-house code was developed for the comparison of the literature-reported Cps and those resulting from the mixing rule. It was discovered that the Cp of the fluidized bed had a proportional increase with the increase in the temperature along the length of the kiln. The deviation between the two values (calculated and literature) is relatively small in some cases, whereas, in others, it is quite significant, ranging from 1.56% to 52.49%, thus making the adoption of the temperature-dependence of Cp necessary. Establishing a more accurate relation for the specific heat capacity leads to a better energy balance inside the kiln, which, along with other improvements, can lead to a decrease in the energy consumed and a significant reduction in greenhouse gas emissions.

Physchem doi: 10.3390/physchem6010009

Authors: Fernando Aricapa Jorge L. Gallego Alejandro Silva-Cortés Claudia Díaz-Mendoza Jorgelina Pasqualino

In regions with abundant solar energy, solar water disinfection (SODIS) offers a sustainable strategy to improve drinking water access, especially in rural, off-grid communities. This study presents a numerical modeling approach to assess the thermal and microbial disinfection performance of glass-free parabolic trough collectors (PTCs). The model integrates geometric sizing, one-dimensional thermal energy balance, and first-order microbial inactivation kinetics, supported by optical simulations in SolTRACE 3.0. Simulations applied to a representative case in the Colombian Caribbean (Gambote, Bolívar) highlight the influence of rim angle, focal length, and optical properties on system efficiency. Results show that compact PTCs can achieve fluid temperatures above 70 °C and effective pathogen inactivation within short exposure times. Sensitivity analysis identifies key geometric and environmental factors that optimize performance under variable conditions. The model provides a practical tool for guiding the design and local adaptation of SODIS systems, supporting decentralized, low-cost water treatment solutions aligned with sustainable development goals. Furthermore, it offers a framework for future assessments of PTC implementations in different climatic scenarios.

Physchem doi: 10.3390/physchem6010008

Authors: Edwin Rivera Oriana Avila Ruben Fonseca

This study investigates how different substituents modulate the electronic structure and optical properties of seven derivatives of Pyrimidine-benzoxazole (FB.01) in DMSO, aiming to optimize their performance as deep bioimaging probes. The π-conjugated FB.01 core was functionalized with methyl, phenyl, N-oxide, exocyclic phenyl, carboxyl, N(OH)2, and pyridine. Geometry optimizations were performed using DFT (B3LYP/6-311+G(d,p) with SMD), followed by analysis of frontier orbitals, electronegativity, hardness, and total energy. TD-DFT and the Sum-Over-States approach simulated molar absorptivity spectra and two-photon absorption cross-sections. Results show that minor torsions influence optical responses: the FB.01 skeleton remains nearly planar, though substituents alter π-overlap and shift the LUMO, while the HOMO stays at −7.65 eV. N-oxide and carboxyl groups stabilize the LUMO, narrowing the energy gap (down to 5.20 eV in FB.04 and 6.07 eV in FB.06), whereas methyl widens it (6.38 eV). All compounds preserve a strong UV-band; conjugation increases absorptivity, and FB.04 exhibits a 31 nm red-shift. TPA grows with conjugation and peaks dramatically in FB.04 (23 GM), surpassing other derivatives. These findings highlight three design principles: strong acceptors like N-oxide effectively lower the LUMO and enhance TPA; additional aromatic rings boost one-photon absorption; and carboxyl or N(OH)2 groups finely tune polarity without disrupting planarity.

Physchem doi: 10.3390/physchem6010007

Authors: Piotr Kałuziak Jan Raczyński Semir El-Ahmar Katarzyna Kwiecień Marta Przychodnia Wiktoria Reddig Agnieszka Żebrowska Wojciech Koczorowski

Studies on two-dimensional materials (such as topological insulators or transition metal dichalcogenides) have shown that they exhibit unique properties, including high charge carrier mobility and tunable bandgaps, making them attractive for next-generation electronics. Some of these materials (e.g., HfSe2) also offer thickness-dependent bandgap engineering. However, the standard device fabrication techniques often introduce processing contamination, which reduces device efficiency. In this paper, we present a modified mechanical exfoliation technique, the Reversed Structuring Procedure, which enables the fabrication of hybrid systems based on 2D microflakes with improved interface cleanness and contact quality. Hall effect measurements on Bi2Se3 and HfSe2 devices confirm enhanced electrical performance, including the decrease in the measured total resistance. We also introduce a novel Star-Shaped Electrode Structure, which allows for accurate Hall measurements and the exploration of geometric magnetoresistance effects within the same device. This dual-purpose geometry enhances the flexibility and demonstrates broader functionality of the proposed fabrication method. The presented results validate the Reversed Structuring Procedure method as a robust and versatile approach for laboratory test-platforms for electronic applications of new types of layered materials whose fabrication technology is not yet compatible with CMOS.

Physchem doi: 10.3390/physchem6010006

Authors: Yufei Sha Yi Zhang Kangjian Tang

Low-temperature CO oxidation is crucial for applications like gas purification and exhaust treatment, with ceria-based catalysts being highly promising. However, conventional synthesis methods often require energy-intensive calcination, releasing harmful gaseous contaminants. To address this, we demonstrate a facile and environmentally friendly method for preparing Ga2O3/CeO2 catalysts by substituting gallium salt solution with liquid gallium, followed by room-temperature ball milling (BM). The resulting 1.5% Ga2O3-CeO2 catalyst, milled at 300 rpm for 60 min, exhibited catalytic activity starting at 100 °C and achieved complete CO conversion at 300 °C. This work presents an economical and sustainable strategy that utilizes liquid metals to prepare high-performance ceria-based catalysts, offering a green alternative to traditional synthesis routes that rely on metal salts and high-temperature treatments.

Physchem doi: 10.3390/physchem6010005

Authors: Juan Francisco Ramos-Justicia Ana Urbieta Paloma Fernández

This study takes a further step forward in the analytical treatment of Langmuir–Hinshelwood (LH) kinetics for heterogeneous catalysis by deriving its closed-form solution. Unlike previous studies, we present a general solution that does not impose severe restrictions on the experimental conditions. This solution not only recovers the typical first- and zeroth-order regimes but also enables the simultaneous determination of the reaction rate constant and absorption–desorption equilibrium constant, unlike the traditional approaches to this equation, which needed additional isotherm experiments. The final solution requires a fine mathematical treatment for its numerical implementation, but enhanced approximations of the closed-form solution overcome this problem without losing the main advantage of calculating both constants at the same time. A parameter called “critical time” has been introduced, whose calculation allows us to distinguish quantitatively between kinetic regimes. Finally, the validation of these approximations has been carried out with experiments on zinc oxide and anatase (TiO2) under different conditions. Anatase experiments undoubtedly show a first-order tendency, regardless the quantity of powder. On the other hand, the degradation regime of the ZnO case cannot be easily ascribed to the zeroth or first order by simple inspection, but the model can mathematically rule out the zeroth order and confirm that it undergoes first-order degradation.

Physchem doi: 10.3390/physchem6010004

Authors: Junli Li Chaoke Bulin Jinling Song Bangwen Zhang Xiaolan Li

This study aims to fabricate magnesium-doped SiOx materials through the integrated application of physical vapor deposition and chemical vapor deposition techniques, with the objective of developing high-performance anode materials for lithium-ion batteries. With the macroscopic particle size held constant, this study endeavors to explore the impact of variations in the size of microscopic silicon crystals on the properties of the material. Under the effect of magnesium doping, the influence mechanism of different microscopic grain sizes on the reaction kinetics behavior and structural stability of the material was systematically studied. Based on the research findings, a reasonable control range for the size of silicon crystals will be proposed. The research findings indicate that both relatively small and large silicon crystals are disadvantageous for cycling performance. When the silicon crystal grain size is 5.79 nm, the composite material demonstrates a relatively high overall capacity of 1442 mAh/g and excellent cycling stability. After 100 cycles, the capacity retention rate reaches 83.82%. EIS analysis reveals that larger silicon crystals exhibit a higher lithium ion diffusion coefficient. As a result, the silicon electrodes show more remarkable rate performance. Even under a high current density of 1C, the capacity of the material can still be maintained at 1044 mAh/g.

Physchem doi: 10.3390/physchem6010003

Authors: Atanas Terziyski Peter Behr Nikolay Kochev Peer Scheiff Reinhard Zellner

A kinetic and thermodynamic multi-phase model has been developed to describe the adsorption of gases on ice surfaces and their subsequent diffusional loss into the bulk ice phase. This model comprises a gas phase, a solid surface, a sub-surface layer, and the ice bulk. The processes represented include gas adsorption on the surface, solvation into the sub-surface layer, and diffusion in the ice bulk. It is assumed that the gases dissolve according to Henry’s law, while the surface concentration follows the Langmuir adsorption equilibrium. The flux of molecules from the sub-surface layer into the ice bulk is treated according to Fick’s second law. Kinetic and thermodynamic quantities as applicable to the uptake of small carbonyl compounds on ice surfaces at temperatures around 200 K have been used to perform model calculations and corresponding sensitivity tests. The primary application in this study is acetic acid. The model simulations are applied by fitting the experimental data obtained from coated-wall flow-systems (CWFT) measurements, with the best curve-fit solutions providing reliable estimations of kinetic parameters. Over the temperature range from 190 to 220 K, the estimated desorption coefficient, kdes, varies from 0.02 to 1.35 s−1, while adsorption rate coefficient, kads, ranges from 3.92 and 4.17 × 10−13 cm3 s−1, and the estimated diffusion coefficient, D, changes by more than two orders of magnitude, increasing from 0.03 to 13.0 × 10−8 cm2 s−1. Sensitivity analyses confirm that this parameter estimation approach is robust and consistent with underlying physicochemical processes. It is shown that for shorter exposure times the loss of molecules from the gas phase is caused exclusively by adsorption onto the surface and solvation into the sub-surface layer. Diffusional loss into the bulk, on the other hand, is only important at longer exposure times. The model is a useful tool for elucidating surface and bulk process kinetic parameters, such as adsorption and desorption rate constants, solution and segregation rates, and diffusion coefficients, as well as the estimation of thermodynamic quantities, such as Langmuir and Henry constants and the ice film thickness.

Physchem doi: 10.3390/physchem6010002

Authors: Zhipeng He Jae-Ho Kim Susumu Yonezawa

Polylactic acid (PLA) films were directly fluorinated using fluorine gas at room temperature under varying conditions: fluorine concentrations of 190–760 Torr and reaction times of 10–60 min. Some of the fluorinated samples were subsequently dried at 70 °C for 2 d. Fourier-transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses verified the successful introduction of fluorine and the formation of -CFx and C=OF groups on the PLA surface after fluorination. The fluorination level initially increased with increasing reaction time or fluorine concentration but then decreased because of the formation and escape of CF4 gasification. Drying further reduced the surface fluorine content. Both fluorination and drying increased the glass transition temperature of PLA, which was attributed to the increase in surface polarity and crosslinking density of the polymer. Fluorination significantly improved the surface hydrophilicity of PLA, with the water contact angle decreasing from 64.09°to 18.75°. This was due to the formation of a rough, porous surface caused by the introduction of polar fluorine atoms, as observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). However, drying the fluorinated samples increased the water contact angle to 91.46°, resulting in hydrophobicity owing to increased surface crosslinking. This study demonstrates a simple and effective method for tuning the hydrophilic–hydrophobic properties of PLA surfaces using direct fluorination and thermal treatment.

Physchem doi: 10.3390/physchem6010001

Authors: Dhruv Suraneni Balasubramanian Deepika Kavinithi Jaganathan Mahadevan Sanjana Raghupathy Shangavy Pandiarajan Devadass Jessy Mercy Agnishwar Girigoswami Sanjay Kisan Metkar Surajit Hansda Koyeli Girigoswami

The field of nanotechnology has witnessed a paradigm shift towards eco-friendly and sustainable synthesis methods for nanoparticles due to increasing concerns over environmental toxicity and resource sustainability. Among various metal oxide nanoparticles, zirconium dioxide (ZrO2) nanoparticles have garnered significant attention owing to their exceptional thermal stability, biocompatibility, mechanical strength, and catalytic properties. Doping ZrO2 with transition metals such as copper (Cu) further enhances its physicochemical attributes, including antibacterial activity, redox behaviour, and electronic properties, rendering it suitable for a diverse range of biomedical and industrial applications. In the present study, we report the green synthesis of copper-doped ZrO2 nanoparticles (Cu-ZrO2-CO NPs) using an aqueous extract of Calendula officinalis (marigold) flowers as a natural reducing and stabilizing agent. The complete characterization was performed using UV–vis spectrophotometry, dynamic light scattering (DLS), zeta potential, FTIR, SEM, EDAX, and XRD, revealing its size to be around 20–40 nm and zeta potential as −20 mV, indicating nano size and stability. The biocompatibility of the as-synthesized nanoparticle was analyzed in vitro using fibroblast cell viability and haemolysis assay, and in vivo using brine shrimp assay. The nanoparticles were safe up to a dose of 50 μg/mL, showing more than 95% cell viability and less than 2% haemolysis, which is within an acceptable range. Finally, the anticancer activity was explored for A549 cells by MTT assay and live-dead assay, with an IC50 value of 38.63 μg/mL. The chorioallantoic membrane (CAM) model was used to assess the anti-angiogenesis potential of the Cu-ZrO2-CO NPs. The results showed that the nanoparticles could kill the cancer cells via apoptosis, and one of the reasons for the anticancer effect was angiogenesis inhibition. Further research is needed using other cancer cell lines and animal tumour models.

Physchem doi: 10.3390/physchem5040057

Authors: Maya Kebaili Amina Ghedjemis Lilia Benchikh Yazid Aitferhat Ilyes Abacha Kamel Hebbache Cherif Belebchouche El Hadj Kadri

Metallic implants used in orthopedics, such as titanium alloys, possess excellent mechanical strength but suffer from corrosion and poor bio-integration, often necessitating revision surgeries. Bioactive coatings, particularly hydroxyapatite, can enhance implant osteoconductivity, but high-purity synthetic hydroxyapatite is costly. This study investigates the development and characterization of a low-cost, biocompatible coating using hydroxyapatite derived from an unconventional natural source dromedary bone applied onto a titanium substrate via plasma spraying. Hydroxyapatite powder was synthesized from dromedary femurs through a thermal treatment process at 1000 °C. The resulting powder was then deposited onto a sandblasted titanium dioxide substrate using an atmospheric plasma spray technique. The physicochemical, structural, and morphological properties of both the source powder and the final coating were comprehensively analyzed using Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, X-ray Diffraction, and Fourier-Transform Infrared Spectroscopy. Characterization of the powder confirmed the successful synthesis of pure, crystalline hydroxyapatite, with Fourier-Transform Infrared Spectroscopy analysis verifying the complete removal of organic matter. The plasma-sprayed coating exhibited good adhesion and a homogenous, lamellar microstructure typical of thermal spray processes, with an average thickness of approximately 95 μm. X-ray Diffraction analysis of the coating revealed that while hydroxyapatite remained the primary phase, partial decomposition occurred during spraying, leading to the formation of secondary phases, including tricalcium phosphate and calcium oxide. Scanning Electron Microscopy imaging showed a porous surface composed of fully and partially melted particles, a feature potentially beneficial for bone integration. The findings demonstrate that dromedary bone is a viable and low-cost precursor for producing bioactive hydroxyapatite coatings for orthopedic implants. The plasma spray method successfully creates a well-adhered, porous coating, though process-induced phase changes must be considered for biomedical applications.

Physchem doi: 10.3390/physchem5040056

Authors: Afrodite Tryfon George Petsis Panagiota Siafarika Evanthia Soubasi Angelos G. Kalampounias

This study presents a systematic investigation of the dynamic and structural characteristics of St. John’s wort (Hypericum perforatum) in alcoholic solutions using experimental and theoretical techniques. Ultrasonic relaxation spectroscopy was employed to investigate medium-range dynamic processes, while density functional theory (DFT) calculations were employed to explore the molecular structure and vibrational properties of the system. Theoretical calculations revealed two Hyperforin conformers, a keto derivative, and three protonated species. Acoustic spectra revealed three distinct Debye-type relaxation processes, corresponding to conformational changes in hyperforin, enol-to-keto tautomerization, and proton transfer mechanisms. In addition, St. John’s wort oil (Oleum Hyperici) was studied, using attenuated total reflection (ATR) infrared spectroscopy for several extraction intervals. These spectra were compared with the theoretical IR spectra of hypericin, hyperforin, and its derivatives, confirming the presence of hyperforin, keto, and two protonated species in the oil. Besides structural and dynamical evaluations, the study assessed the toxicity and biological activity of hyperforin and all species found in the solutions, offering information about potential pharmaceutical uses, suggesting that hyperforin and its keto form have the best antidepressant activity. This comprehensive analysis enhances the understanding of hyperforin’s molecular behavior and strengthens the therapeutic potential of St. John’s wort as a natural antidepressant agent.

Physchem doi: 10.3390/physchem5040055

Authors: Christian Ebere Enyoh Tochukwu Oluwatosin Maduka Qingyue Wang Miho Suzuki Ifunanya Scholastica Enyoh

Polyethylene terephthalate-derived fluorescent carbon quantum dots (PET-CQDs) are promising nanomaterials for sensing and biomedical uses, yet their biological interactions after metal doping require careful evaluation. Here, we report an in silico assessment of pristine and dual-site (via graphitic [G] and carbonyl [O]) metal-doped PET-CQDs (Ca, Mg, Fe, Zn) using molecular docking against eight human proteins: HSA (distribution), CYP3A4 (metabolism), hemoglobin (systemic biocompatibility), transferrin (uptake), GST (detoxification), ERα (endocrine regulation), IL-6 (inflammation), and caspase-3 (cytotoxic signaling) together with ADMET profiling and DFT–docking correlation analysis. Docking affinities were compared with controls and ranged from −7.8 to −10.4 kcal·mol−1 across systems, with binding stabilized by π–π stacking, hydrogen bonding and metal–ligand coordination involving residues such as arginine, tyrosine and serine. Importantly, top-performing CQD variants differed by target: PET-CQDs, MgG_PET-CQDs and FeG_PET-CQDs were best for GST; ERα interacted favorably with all doped variants; IL-6 bound best to CaO_PET-CQDs and FeO_PET-CQDs (≈−7.1 kcal·mol−1); HSA favored CaG_PET-CQDs (−10.0 kcal·mol−1) and FeO_PET-CQDs (−9.9 kcal·mol−1); CYP3A4 bound most strongly to pristine PET-CQDs; hemoglobin favored MgG_PET-CQDs (−9.6 kcal·mol−1) and FeO_PET-CQDs (−9.3 kcal·mol−1); transferrin favored FeG_PET-CQDs; caspase-3 showed favored binding overall (pristine −6.8 kcal·mol−1; doped −7.4 to −7.6 kcal·mol−1). ADMET predictions indicated high GI absorption, improved aqueous solubility for some dopants (~18.6 mg·mL−1 for Ca-O/Mg-O), low skin permeability and no mutagenic/carcinogenic flags. Regression analysis showed frontier orbital descriptors (HOMO/LUMO) partially explain selective affinities for ERα and IL-6. These results support a target-guided selection of PET-CQDs for biomedical applications, and they call for experimental validation of selected dopant–target pairs.

Physchem doi: 10.3390/physchem5040054

Authors: Qiyao Zhang Jingchao Zhu Lichao Fu Dapeng Liu Yu Zhang

With the surging demand for high-performance energy storage devices, enhancing the energy density and charge-discharge efficiency of lithium-ion batteries has become an urgent need. Co3O4, with a high theoretical specific capacity of 890 mAh g−1, is regarded as a promising anode candidate. In this work, rod-like hybrid Co3O4/SnO2 composites were successfully prepared via the pyrolysis of cobalt-tin ethylene glycolate precursor. Notably, when the Co/Sn molar ratio is tuned to 3.8:1, the product evolves into nanorods. Lithium-ion batteries using Co3.8Sn1 as the anode deliver an initial specific capacity of 1588.9 mAh g−1, and retain a reversible capacity of 427.9 mAh g−1 after 500 cycles at 2 A g−1, demonstrating that Sn-doping-induced optimization of morphology and conductivity effectively enhances electrochemical performance.

Physchem doi: 10.3390/physchem5040053

Authors: Valeriy V. Bezrodnyi Sofia E. Mikhtaniuk Alexey Y. Vakulyuk Igor M. Neelov Nadezhda N. Sheveleva Denis A. Markelov Oleg V. Shavykin

Fullerenes are promising drug candidates, but they are virtually insoluble in water. Surface hydroxylation of fullerenes and their encapsulation in nanocarrier systems, such as dendrimers, can be used to increase their solubility. However, hydroxylated fullerene (hydroxyfullerene, fullerenol) has lower bioactivity than fullerene. Our previous research showed that fullerene is encapsulated by the Lys-2Gly dendrimer. This study demonstrates, for the first time, that hydroxylated fullerenes C60(OH)n with n = 12, 24, 36 form complexes with the same dendrimer. All these fullerenols are encapsulated near the dendrimer’s center, similar to fullerene. Surprisingly, the complex’s structure remains stable even at the maximal hydroxylation (n = 36), despite a significant reduction in hydrophobicity of the fullerene surface. We demonstrated that this stability results from an increase in the number of hydrogen bonds between the dendrimer and the fullerenol with increasing n. Thus, we established that the mechanism of complex formation changes from hydrophobic interactions to hydrogen bonding as hydroxylation increases. This means that simultaneous partial hydroxylation of the fullerene and encapsulation within a water-soluble dendrimeric nanocarrier enhances its solubility in water. This combined approach enables the use of less hydroxylated fullerene derivatives to achieve desired solubility while maintaining higher biological activity.

Physchem doi: 10.3390/physchem5040052

Authors: Sushovan Chatterjee Sagar Roy

The optimization of biodiesel production through experimental design and statistical modeling carries significant industrial and economic benefits. The utilization of Response Surface Methodology (RSM) and statistical modeling permits accurate manipulation of the crucial process parameters. In this work, a statistical model was effectively applied to optimize two major process parameters (namely reaction time and reaction temperature) for the production of biodiesel during the transesterification of palm oil. The transesterification of palm oil was studied using experiments designed through RSM to determine the optimal reaction conditions. Based on the statistical model generated by RSM, the optimal parameters for maximizing methyl ester yield were identified as a reaction time of 343 min and a temperature of 58.3 °C. Under these conditions, the model predicted a methyl ester yield of 83.57%. Experimental validation under the same conditions resulted in a yield of 83.80%, closely aligning with the predicted value and confirming the model’s reliability.

Physchem doi: 10.3390/physchem5040051

Authors: Khansae Kamal Zahira Belattmania Khaoula Khaya Abdellatif Chaouti Fouad Bentiss Charafeddine Jama Valérie Stiger-Pouvreau Brahim Sabour

The unprecedented influx of pelagic Sargassum represents both a serious ecological concern and a potential opportunity regarding biopolymer production. Assessing the quality, preservation status, and processing potential of these species is crucial to transforming this environmental challenge into a sustainable benefit for industrial valorization. In the present work, we investigated the alginate yields (21.2 ± 0.57% and 18.1 ± 0.11% dw) and the structural characteristics of sodium alginates extracted from Sargassum natans and Sargassum fluitans encountered drifting along Moroccan coasts, respectively. The FTIR analysis indicated that the extracted alginates from both species exhibited similar spectral profile of the commercial alginate obtained from Sigma-Aldrich. The 1H NMR spectra of the extracted alginates displayed characteristic signals for monads M and G and diads MM, GG, and MG/GM, consistent with M/G ratios above 1, with fairly abundant heteropolymeric fractions (FGM/FMG) accounting for more than 52% of the polymer diads. Intrinsic and molecular weight analyses revealed differences between S. natans ([η] = 1.39 dL/g; Mw = 0.65 × 10−5 g/mol) and S. fluitans ([η] = 0.80 dL/g; Mw = 0.37 × 10−5 g/mol). Both values are comparable to commercial alginate but remarkably lower in viscosity. Consequently, alginates from these species are foreseen to form elastic, flexible, and softer gels, making them suitable for applications such as drug delivery, cancer therapy, bioactive encapsulation, controlled nutrient release, and environmental remediation.

Physchem doi: 10.3390/physchem5040050

Authors: Ioannis Tanis

The manufacturing of detergent products such as laundry detergents or household cleaners is of increasing interest to the chemical industry. Surfactants and fatty acids are the most important ingredients in detergent formulations, as they are responsible for the cleaning power and the antimicrobial efficiency of the cleaning product. Computational tools can play a key role in the design and performance optimization of detergent products as they allow for quick and efficient screening of candidate surfactants in detergent formulations. In the present study, an automated fragmentation and parametrization protocol is utilized to investigate the adsorption of candidate fatty acid surfactants towards bacterial inner membranes. The effect of the surfactant size, concentration, and tendency for micelle formation on the degree of their adsorption on the inner membrane is examined. Analysis demonstrates that surfactant–inner membrane interaction weakens with surfactant size and aggregation tendency, as confirmed by pertinent experimental and simulation studies. The outcome of this study demonstrates that the adopted multiscale protocol allows for an accurate and cost-effective description of the systems examined at timescales much shorter than those required in laboratory experiments and atomistic simulations.

Physchem doi: 10.3390/physchem5040049

Authors: Yuika Sakaguchi Kosuke Ikezoi Toshiyuki Abe

Hydrogen peroxide (H2O2) is a clean and environmentally friendly oxidant. At present, as an alternative to the conventional industrial procedure, namely, the anthraquinone method, a clean H2O2 production method is desired. The construction of an artificial photosynthetic system in which H2O2 can ideally be prepared from water and dioxygen (O2) is a promising approach. In such a system, an organic p-n bilayer comprising zinc phthalocyanine (ZnPc, p-type) and fullerene (C60, n-type) acts as a photocathode capable of O2 reduction to H2O2, where loading gold (Au) onto the C60 surface is necessary to achieve the corresponding reaction. However, the enhancement of the photocathodic activity of the organic p-n bilayer for H2O2 formation remains a critical issue. In this study, the effect of the thickness of an organo-bilayer (organo-photocathode) on photocathodic activity for H2O2 production was investigated. When both ZnPc and C60 were thin (approximately 10 nm each in thickness), the photocathodic activity of the ZnPc/C60 organo-photocathode was approximately 3.4 times greater than that of the thick ZnPc/C60 bilayer (i.e., ZnPc = ca. 70 nm and C60 = ca. 120 nm). The thin ZnPc/C60 bilayer exhibited a built-in potential at the p-n interface, where efficient charge separation occurs, resulting in a high concentration of electrons available for O2 reduction.

Physchem doi: 10.3390/physchem5040048

Authors: Florence Acha Daniel Egbebunmi Shamsudeen Ahmadu Aishat Ojuolape Titus Egbosiuba

Bio-inspired superhydrophobic coatings have garnered significant attention in recent years due to their potential in creating self-cleaning and anti-icing surfaces. Drawing inspiration from natural systems such as lotus leaves and insect wings, these coatings leverage hierarchical nanostructures to achieve extreme water repellency and low surface adhesion. This review explores recent advances in the design, fabrication, and functional performance of bio-inspired superhydrophobic materials, with a focus on hierarchical micro/nanostructured surfaces. We discuss the underlying mechanisms of wettability, the role of surface chemistry, and the integration of durable nanostructures for enhanced durability. Additionally, the paper discusses the latest progress in scalable manufacturing techniques, environmental adaptability, and multifunctional performance, particularly in self-cleaning and anti-icing applications. Emerging trends, such as stimuli-responsive surfaces and smart coatings, are also examined to provide a comprehensive overview of the field. This review discusses the challenges and future directions for translating laboratory-scale innovations into real-world applications, particularly in aerospace, automotive, energy, and infrastructure sectors.

Physchem doi: 10.3390/physchem5040047

Authors: Zixin Gong Jingyuan Zhong Qiyi Li Huayi Shen Jincheng Zhuang Yi Du

Quasi-one-dimensional (quasi-1D) topological matter Bi4X4 (X = Br, I) possesses versatile topological phases determined by its molar ratio of halide and the stacking mode. Establishing the intrinsic relationship between these topological orders and the quantum transport properties is extremely crucial for both of fundamental research and device applications. Here we review the recent work on the characteristic quantum transport behavior of the Bi4X4 system originating from various electronic states, including three-dimensional (3D) bulk states, two-dimensional (2D) surface states, and one-dimensional (1D) topological hinge states. Specifically, variable range hopping effect, Lifshitz transition, metal–insulator transition, and Shubnikov de Haas oscillations are evoked by the gapped bulk states with significant doping carriers. In 2D limits, the (100) surface states exhibit Dirac-type dispersion to produce weak antilocalization, which is a strong 1D nature due to quasi-1D crystal and electronic structure and evidenced by anomalous planar Hall effect. Last but not the least, coherent transport with Aharonov–Bohm oscillations is observed in thin-layer devices, implying the existence of 1D topological hinge states separated by the (100) surface. These unconventional quantum transport features verify the topological nature of Bi4X4 in different dimensions, signifying an ideal platform to design and utilize multiple topological orders in this quasi-one-dimensional material system.

Physchem doi: 10.3390/physchem5040046

Authors: Anastasiya Bahdanava Lena Golubewa Yaraslau Padrez Nadzeya Valynets Tatsiana Kulahava

One-pot hydrothermal synthesis of boron nitride quantum dots (BNQDs) offers a simple and widely accessible approach to produce nanoparticles with tailored properties for biomedical purposes, including bioimaging and drug delivery. However, growing evidence suggests that most reported BNQD syntheses yield products with insufficient purity and poorly defined structures, limiting their bioapplications where precise composition and controlled synthesis are paramount. In this study, we present a formation mechanism and demonstrate multiple BNQD synthesis pathways that can be precisely controlled by modulating the reaction equilibrium during hydrothermal synthesis under varying experimental conditions. We demonstrate that carbon-related defects shift BNQD photoluminescence (PL) from the UV to the 400–450 nm region, making them suitable for bioimaging, while BO2− enrichment introduces additional phosphorescence. Furthermore, we show that as-synthesized BNQD suspensions contain significant contamination by non-luminescent ammonium polyborate salts, which is overlooked in prior studies, and disclose the mechanism of their formation as well as effective purification method. Finally, we assess the biocompatibility of purified BNQDs with tuned PL properties and demonstrate their application in bioimaging using Vero cells. The elucidated nanoparticle formation mechanisms, combined with methods for precise control of optical properties, structural defects and sample purity, enable the reproducible production of reliable and effective BNQDs for bioimaging.

Physchem doi: 10.3390/physchem5040045

Authors: Khaleke Veronicah Ramollo Lutendo Evelyn Macevele Abayneh Ataro Ambushe Takalani Magadzu

Calcium (Ca2+ ions) is one of the dominant elements that contribute to water hardness, scaling in pipes, bathroom faucets, and kitchen utensils. Herein, we report on the development of poly(vinylidene fluoride-co-hexafluoropropylene) cellulose acetate (PVDF-HFP/CA) films for the treatment of Ca2+ ions as one of the constituents that causes water hardness. CA and PVDF-HFP polymers, and their blend consisting of 3 wt.% PVDF-HFP/CA, were effectively synthesised through the phase inversion technique. Analysis using thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) confirmed the effective incorporation of 3 wt.% PVDF-HFP into the cellulose acetate film. Parameters such as temperature, initial concentration, pH, adsorbent dosage and contact time were investigated in batch studies during the removal of Ca2+ ions in synthetic water samples. Under optimal conditions (pH 7, adsorbent dosage of 0.5 mg/L, and concentration of 120 mg/L), the 3 wt.% PVDF-HFP/CA film achieved a 99% adsorption efficiency for Ca2+ ions in 90 min. The adsorption process adhered to pseudo-second-order and Freundlich isotherm models, which suggest that the adsorption of Ca2+ ions is heterogeneous. The maximum adsorption efficiency achieved was 56 mg/g, indicating an endothermic physisorption process. The 3 wt.% PVDF-HFP/CA film maintained higher adsorption in the presence of counter ions and in a binary system, and it could be recycled at least three times. Thus, the findings demonstrated that the 3 wt.% PVDF-HFP/CA film could be a valuable material for Ca2+ ions removal to acceptable drinking water levels.

Physchem doi: 10.3390/physchem5040044

Authors: Selahattin Celik Gamze Atalmis Sari Mikail Yagiz Hasan Özcan Bahman Amini Horri

This study investigates the impact of vibration frequency on the performance of a 10-cell open-cathode direct methanol fuel cell (OC-DMFC) stack. Experiments were conducted using three different vibration frequencies (15, 30, and 60 Hz) and compared against a baseline condition without vibration. Performance was evaluated under varying methanol–water fuel flow rates (1, 5, 25, and 50 mL·min−1) while maintaining constant operating conditions: methanol temperature at 70 °C, methanol concentration at 1 M, and cathode air flow velocity at 4.8 m·s−1. The optimal performance was observed at a fuel flow rate of 5 mL·min−1, where the maximum power density reached 26.05 mW·cm−2 under 15 Hz vibration—representing a 14% increase compared to the non-vibrated condition. These findings demonstrate that low-frequency vibration can enhance fuel cell performance by improving mass transport characteristics.

Physchem doi: 10.3390/physchem5040043

Authors: Zhipeng He Jae-Ho Kim Susumu Yonezawa

Polyethylene terephthalate (PET) films were modified by direct fluorination using fluorine gas at room temperature and 660 torr for reaction times ranging from 10 min to 5 h. Some of the fluorinated samples were dried at 70 °C for 7 days. FT-IR and XPS analyses confirmed the successful incorporation of fluorine into the PET structure, with the formation of -CHF- and -CF2- groups. The degree of fluorination increased with the reaction time, but excessive reaction led to the formation and loss of CF4. Drying further decreased the fluorine content due to the continued CF4 formation. XRD revealed that fluorination increased the crystallinity of PET owing to increased polarity, whereas drying decreased the crystallinity owing to increased crosslinking. The DSC results showed an increase in the glass transition temperature (Tg) after fluorination and drying, which was attributed to increased polarity and crosslinking, respectively. The surface hydrophilicity of PET increased significantly with fluorination time, and the water contact angle decreased to as low as 3.35°. This was due to the introduction of polar fluorine atoms and the development of a rough and porous surface morphology, as observed by AFM. Interestingly, drying of the fluorinated samples led to an increase in the water contact angle, with a maximum of 85.95°, owing to increased crosslinking and particle formation on the surface. This study demonstrates a simple and effective method for controlling the hydrophilicity and hydrophobicity of PET surfaces via direct fluorination and drying.

Physchem doi: 10.3390/physchem5040042

Authors: Maulida Nur Astriyani Nugraha Edhi Suyatma Vallerina Armetha Eko Hari Purnomo Tjahja Muhandri Faleh Setia Budi Boussad Abbes Ahmed Tara

Ultrasonication offers a safer, lower-temperature method for synthesizing zinc oxide nanoparticles (ZnO-NPs). This study details the development of a pectin-glycerol bionanocomposite film reinforced with ZnO-NPs produced using the top-down ultrasonication method. ZnO-NPs were fabricated with varying ultrasonication durations (0, 30, and 60 min) and the addition of pectin as a capping agent. Extended ultrasonication duration resulted in smaller particle size and more defined morphology. Bionanocomposite films were prepared using the solvent casting method by incorporating ZnO-NPs (0, 0.5, 1, 2.5% w/w) and glycerol (0, 10, 20% w/w) as a plasticizer to a pectin base. The inclusion of ZnO-NPs and glycerol did not affect the shear-thinning behavior of the film-forming solution. FTIR analysis indicated interactions between ZnO-NPs, glycerol, and pectin. The addition of ZnO-NPs and glycerol reduced tensile strength but increased flexibility. ZnO-NPs improved barrier and thermal properties by reducing water vapor permeability and increasing melting point, whereas glycerol lowered glass transition temperature, thus enhancing film flexibility. The best film performance was observed with a combination of 0.5% ZnO and 20% glycerol. These results highlight the effectiveness of the top-down ultrasonication method as a sustainable approach for ZnO-NPs fabrication, supporting the development of pectin/ZnO-NPs/glycerol films as a promising material for eco-friendly packaging.

Physchem doi: 10.3390/physchem5040041

Authors: Qinze Yu Lingtao Zhan Xiongbai Cao Tingting Wang Haolong Fan Zhenru Zhou Huixia Yang Teng Zhang Quanzhen Zhang Yeliang Wang

Over the past decade, two-dimensional materials have become a research hotspot in chemistry, physics, materials science, and electrical and optical engineering due to their excellent properties. Graphene is one of the earliest discovered 2D materials. The absence of a bandgap in pure graphene limits its application in digital electronics where switching behavior is essential. In the present study, researchers have proposed a variety of methods for tuning the graphene bandgap. Machine learning methodologies have demonstrated the capability to enhance the efficiency of materials research by automating the recording of characteristic parameters from the discovery and preparation of 2D materials, property calculations, and simulations, as well as by facilitating the extraction and summarization of governing principles. In this work, we use first principle calculations to build a dataset of graphene band gaps under various conditions, including the application of a perpendicular external electric field, nitrogen doping, and hydrogen atom adsorption. Support Vector Machine (SVM), Random Forest (RF), and Multi-Layer Perceptron (MLP) Regression were utilized to successfully predict the graphene bandgap, and the accuracy of the models was verified using first principles. Finally, the advantages and limitations of the three models were compared.

Physchem doi: 10.3390/physchem5040040

Authors: Fathi Elashhab Lobna Sheha Nada Elzawi Abdelsallam E. A. Youssef

Gellan gum (Gellan), a versatile polysaccharide applied in gel formation and prebiotic formulations, is often processed to tailor its molecular properties. Previous studies employed gamma irradiation and chemical hydrolysis, though without addressing systematic scaling behavior. This study investigates the structural and conformational modifications of Gellan in dilute aqueous salt solutions using a safer and eco-friendly approach: atmospheric low-dose electron beam (e-beam) degradation coupled with viscosity analysis. Native and E-beam-treated Gellan samples (0.05 g/cm3 in 0.1 M KCl) were examined by relative viscosity at varying temperatures, with intrinsic viscosity and molar mass determined via Solomon–Ciuta and Mark–Houwink relations. Molar mass degradation followed first-order kinetics, yielding rate constants and degradation lifetimes. Structural parameters, including radius of gyration and second virial coefficient, produced scaling coefficients of 0.62 and 0.15, consistent with perturbed coil conformations in a good solvent. The shape factor confirmed preservation of an ideal random coil structure despite irradiation. Conformational flexibility was further analyzed using theoretical models. Transition state theory (TST) revealed that e-beam radiation lowered molar mass and activation energy but raised activation entropy, implying reduced flexibility alongside enhanced solvent interactions. The freely rotating chain (FRC) model estimated end-to-end distance (Rθ) and characteristic ratio (C∞), while the worm-like chain (WLC) model quantified persistence length (lp). Results indicated decreased Rθ, increased lp, and largely unchanged C∞, suggesting diminished chain flexibility without significant deviation from ideal coil behavior. Overall, this work provides new insights into Gellan’s scaling laws and flexibility under aerobic low-dose E-beam irradiation, with relevance for bioactive polysaccharide applications.

Physchem doi: 10.3390/physchem5040039

Authors: Ihsan Ur Rahman Numan Khan Oronzio Manca Bernardo Buonomo Sergio Nardini

Thermal management in heat exchangers is crucial in many industrial, medical, and scientific applications. However, reducing dependency on active energy sources still represents a substantial challenge. In this context, phase change materials (PCMs) offer an effective solution due to their ability to store and release large amounts of latent heat, assisting in passive thermal management. Therefore, this study proposes the use of RT42 PCM inside a box-type shell-and-tube configuration to establish the relationship between flow rate and charging and discharging behavior of PCM. In the proposed system, heat transferring fluid (HTF) water is circulated in the internal tubes at 60 °C, where the temperature is monitored by a series of thermocouples strategically placed inside the box-type configuration. To evaluate the effect of the flow of HTF on the thermal behavior of the PCM, the charging (melting) and discharging (solidification) analysis is performed by varying the water flow rate at three levels: 1.2, 0.8, and 0.4 L/min inside the laminar region (Re < 2300). A thermal camera and two webcams were used to assess the surface temperature distribution and PCM response, respectively. It was determined that increasing the flow rate accelerates charging and discharging with fluctuations in temperature curves during melting.

Physchem doi: 10.3390/physchem5030038

Authors: Diego Ezequiel Velazquez María Emilia Latorre

Animal tissue by-products, rich in collagen, represent a valuable source of biomaterials. Understanding their physicochemical and thermal behavior is essential for expanding their applications. In this study, pigskin gelatin was extracted through acid hydrolysis using a combination of acetic acid (AH) and either lactic, citric, or ascorbic acid (75:25, v:v, [0.5 M]), followed by thermal denaturation. We evaluated the physicochemical properties of the gelatin solutions (pH, hydroxyproline content, and extraction yield), as well as the macroscopic gel characteristics. Gelatin films were then prepared and analyzed for moisture content, color, and thermal properties. One-way ANOVA was applied to compare treatments, and Pearson’s correlation was used to assess the relationship between the solution pH and physicochemical parameters. Significant differences in the final pH of the solutions were observed among the acid mixture treatments, though the hydroxyproline content and extraction yield were not significantly affected. All gelatin solutions formed stable gels, and the resulting films exhibited similar moisture content. Thermal analysis revealed treatment-dependent variations. Specifically, a significant negative correlation (p < 0.005) was found between the gelatin solution pH and the melting temperature. These results suggest that the use of organic acid mixtures can effectively modulate gelatin properties, offering a versatile approach for tailoring biomaterials for both food and non-food applications.

Physchem doi: 10.3390/physchem5030037

Authors: Cristina Rincón Carlos Armenta-Déu

The paper describes the conversion of carbon dioxide into methanol in a chemical reactor under standard operating conditions. Electro-analytical techniques, cyclic voltammetry, and chrono-amperometry characterize the process. The electrochemical redox reaction develops using various catalyzers to evaluate the performance of the carbon dioxide conversion into methanol process under variable chemical conditions. The results of the applied technique showed an incomplete redox reaction with an electronic change of z = 2.84 on average, below the ideal number, z = 6, that may be due to methanol decomposition (reverse reaction) because the system operates with a reaction constant above the equilibrium value. The methanol production may improve by draining the methanol/water solution from the chemical reactor to reduce the methanol concentration in the electrochemical cell, shifting the forward reaction towards the formation of methanol, increasing the electron change number, which approaches the ideal value, and improving the methanol production efficiency. The draining process shows a significant increase in methanol formation, which depends on the draining flow rate and the catalyzer type. A simulation process shows that if we operate in optimum conditions, with no methanol decomposition through a reverse reaction, the redox reaction fulfills the ideal condition of maximum electronic change. The experimental tests validate the simulation results, showing a relevant increase in the electron change number with values up to z = 4.2 for optimum draining flow rate conditions (0.2 L/s). The experimental results show a relative increase factor of 4.7 in methanol production, meaning we can produce more than four times more methanol compared with no draining techniques. The data analysis shows that the draining flow rate has a threshold of 0.2 L/s, beyond which the extent of the reaction reverses, reducing the methanol formation due to a chemical reaction disequilibrium. The paper concludes that using the draining method, the methanol production mass rate increases significantly from an average value of 20.9 kg/h for non-draining use, considering all catalyzer types, to a range between 91.9 kg/h and 104.3 kg/h, depending on the flow rate. Averaging all values for different flow rates and comparing with the non-draining case, we obtain an absolute methanol production mass rate of 77 kg/h, meaning an incremental percentage of 469.1%, more than four times the initial production. Although the proposed methodology looks promising, applying this procedure on an industrial scale may suffer from restrictions since the chemical reactions intervening in the methanol formation do not perform linearly. According to experimental tests, the best option among the six catalyzers used for methanol production is the plain copper, with copper oxides (Cu2O, CuO) and copper Sulphur (CuS) as feasible alternatives.

Physchem doi: 10.3390/physchem5030036

Authors: Gabrielle E. Harmon-Welch Douglas W. Elliott Nattamai Bhuvanesh Vladimir I. Bakhmutov Janet Blümel

Solid solutions of the metallocenes ferrocene (Cp2Fe), nickelocene (Cp2Ni), and cobaltocene (Cp2Co) have been prepared by manually grinding the components together, or by co-crystallizing them from solution. In the solid solutions Cp2Fe/Cp2Ni and Cp2Co/Cp2Ni, the cyclopentadienyl (Cp) protons relax via dipolar electron–proton interactions, which represent the dominant relaxation mechanism. The 1H T1 relaxation times of the molecules Cp2Ni and Cp2Co, dissolved in CDCl3, and in the solid solutions, show that the relaxation takes place intramolecularly. The relaxation of the protons is propagated exclusively via the unpaired electrons of the metal centers to which their Cp rings are coordinated, due to the large intermolecular distances that are greater than 3.91 Å. In contrast, the intramolecular distances between the electrons of the metal atoms and the protons of their coordinated Cp rings are merely 2.70 Å. Using these intramolecular distances and the 1H T1 relaxation times, the electron relaxation times T1e have been determined as 17 × 10−13 s in CDCl3 solutions and 45 × 10−13 s in the solid state for Cp2Ni. The corresponding T1e times for Cp2Co are calculated as ca. 5 × 10−13 s and 20 × 10−13 s. Grinding Cp2Fe and Cp2Ni together leads to two different 1H T1 relaxation times for the protons of Cp2Fe. The longer T1 relaxation time indicates domains that consist mostly of Cp2Fe molecules. The short T1 times show a close contact of Cp2Fe and Cp2Ni molecules. An analysis of the short 1H T1 times reveals the presence of at least two to three short distances of 3.91 Å between Cp2Fe and Cp2Ni molecules. These results support the hypothesis that dry grinding of the metallocenes Cp2Fe and Cp2Ni in ratios that were changed in 10% increments from 90%/10% to 30%/70% leads to domains that mostly consist of Cp2Fe molecules, and additionally to domains that contain a mixture of the components on the molecular level.

Physchem doi: 10.3390/physchem5030035

Authors: María Lizbeth Barrios-Reyna Enrique Sánchez-Mora Enrique Quiroga-González

Intergrown mixtures of nanostructured manganese oxide phases have been obtained using a highly complexing agent (ethylenediamine) and a weak complexer (urea) during their solvothermal synthesis. In this work, through a detailed structural analysis, it is evidenced the formation of an intergrown mixture of three distinct manganese oxide phases (β-MnO2, α-Mn2O3, and Mn3O4). Scanning electron microscopy shows that the products have just one morphology, indicating that the different manganese oxide phases may have grown together, organizing themselves in a 3D crystal network. The reaction mechanisms are discussed in this paper. It is of great interest to produce intergrown mixtures of manganese oxide phases to take advantage of the availability of the different oxidation states of Mn in neighboring crystallites for applications like catalysis.

Physchem doi: 10.3390/physchem5030034

Authors: Mione Uchimura Akiteru Ohtsu Junki Tomita Yoshiyuki Ishida Daisuke Nakata Keiji Terao Yutaka Inoue

In this study, supramolecular inclusion complexes composed of komecosanol (Ko), a lipophilic compound derived from rice bran, and α-cyclodextrin (αCD) were prepared using a solvent-free three-dimensional (3D) ball milling method. Their physicochemical properties were examined using various techniques. Powder X-ray diffraction analysis of the ground mixture at a Ko/αCD ratio of 1/8 revealed the disappearance of diffraction peaks characteristic of Ko and the emergence of new peaks, indicating the formation of a distinct crystalline phase. Moreover, differential scanning calorimetry analysis showed the disappearance of the endothermic peaks corresponding to Ko, indicating molecular-level interactions with αCD. Near-infrared spectroscopy results suggested the formation of hydrogen bonds between the C–H groups of Ko and the O–H groups of αCD. Solid-state 13C CP/MAS NMR and T1 relaxation time measurements indicated the formation of a pseudopolyrotaxane structure, while scanning electron microscopy images confirmed distinct morphological changes consistent with complex formation. These findings demonstrate that 3D ball milling facilitates the formation of Ko/αCD inclusion complexes with a supramolecular architecture, providing a novel approach to improve the formulation and bioavailability of poorly water-soluble lipophilic compounds.

Physchem doi: 10.3390/physchem5030033

Authors: Tayeb Ben Kouider Lahcene Souli Yazid Derouiche Taoufik Soltani Ulrich Maschke

The synthesis of Fe3O4 and ε-Fe2O3 nanoparticles (hereafter referred to as Fe3O4 NPs and ε-Fe2O3 NPs, respectively) was conducted in an eco-friendly manner using FeCl3·6H2O as the primary reactant. The experiment was conducted by subjecting the sample to an aqueous solution of FeCl2·4H2O at a temperature of 80 °C for a duration of 45 min, with the inclusion of apricot kernel shell extract (AKSE) as a natural reducing agent. The synthesized Fe3O4 NPs and ε-Fe2O3 NPs were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The optical properties of Fe3O4 NPs and ε-Fe2O3 NPs were examined, with the band gap energy estimated using the Kubelka–Munk formula. The results demonstrated a band gap of Eg (Fe3O4 NPs) = 2.59 eV and Eg (ε-Fe2O3 NPs) = 2.75 eV, thereby confirming their semiconductor behavior. The photoconductivity of Fe3O4 NPs and ε-Fe2O3 NPs was analyzed as a function of photon energy. For Fe3O4 NPs, photoconductivity exhibited an increase between 1.37 eV and 6.2 eV prior to reaching a state of stability. A comparable trend was observed for ε-Fe2O3 NPs, with an increase from 1.35 eV to 6.22 eV, followed by stabilization. Furthermore, the extinction coefficient (k) was determined. For Fe3O4 NPs, k ranged from 39 to a maximum of 300, while for ε-Fe2O3 NPs, it varied from 37 to a maximum of 280. A higher k value indicates strong light absorption, rendering these nanoparticles highly suitable for photothermal and sensing applications.

Physchem doi: 10.3390/physchem5030032

Authors: Muhamad Hawari Mansor Lydia Williamson Daniel Ludwikowski Faith Howard Munitta Muthana

Pectin is a renewable polysaccharide valued for its gelling, stabilising, and encapsulating properties, with broad applications in food, pharmaceutical, and industrial sectors. However, extraction conditions critically affect its yield, structural integrity, and functional performance. Despite citrus peel being a major source of pectin, large amounts remain underutilised as waste. This study systematically investigates how different acid types influence the extraction efficiency and structural quality of pectin derived from citrus peel. Dried citrus peel powder was extracted using four acids—sulphuric, hydrochloric, acetic, and citric—under controlled conditions at 80 °C. Extractions were performed at a fixed time of 90 min for all acids, with additional time trials for sulphuric acid. Extracted pectins were evaluated for gravimetric yield, colour, solubility, degree of esterification (DE) by titration and FTIR, and structural features using FTIR and 1H NMR spectroscopy. Results showed that sulphuric and hydrochloric acids yielded the highest pectin recoveries (30–35% and 20–25%, respectively) but caused significant degradation, evident from dark colour, broad FTIR peaks, low DE (<10%), and poor solubility. In contrast, acetic and citric acid extractions resulted in moderate yields (8–15%) but preserved the pectin backbone and maintained higher DE (>30%) compared to the mineral acid-extracted samples and the commercial low methoxyl (LM) standard, as confirmed by clear FTIR and NMR profiles. These findings demonstrate the trade-off between extraction yield and structural integrity, underscoring the potential of mild organic acids to produce high-quality pectin suitable for value-added applications. Optimising acid type and extraction conditions can support sustainable waste valorisation and expand the industrial use of citrus-derived pectin.

Physchem doi: 10.3390/physchem5030031

Authors: Nawshin Farzana Abu Naser Md Ahsanul Haque Shamima Akter Smriti Abu Sadat Muhammad Sayem Fahmida Siddiqa Md Azharul Islam Md Nasim S M Kamrul Hasan

Anthraquinone acid dyes are widely used in dyeing polyamide due to their good exhaustion and brightness. While ionic interactions primarily govern dye–fiber bonding, the molecular weight (Mw) of these dyes can significantly influence migration, apparent color strength, and fastness behavior. This study offers comparative insight into how the Mw of structurally similar anthraquinone acid dyes impacts their diffusion, fixation, and functional outcomes (e.g., UV protection) on polyamide 6 fabric, using Acid Blue 260 (Mw~564) and Acid Blue 127:1 (Mw~845) as representative low- and high-Mw dyes. The effects of dye concentration, pH, and temperature on color strength (K/S) were evaluated, migration index and zeta potential were measured, and UV protection factor (UPF) and FTIR analyses were used to assess fabric functionality. Results showed that the lower-Mw dye exhibited higher migration tendency, particularly at increased dye concentrations, while the higher-Mw dye demonstrated greater color strength and superior wash fastness. Additionally, improved UPF ratings were associated with higher-Mw dye due to enhanced light absorption. These findings offer practical insights for optimizing acid dye selection in polyamide coloration to balance color performance and functional attributes.

Physchem doi: 10.3390/physchem5030030

Authors: Gabriel A. Silvestrin Marco Andreoli Edson P. Soares Elita F. Urano de Carvalho Almir Oliveira Neto Rodrigo Fernando Brambilla de Souza

A scalable synthesis of two-dimensional titanium nitride chloride (TiNCl) via flash Joule heating (FJH) using titanium tetrachloride (TiCl4) precursor has been developed. This single-step method overcomes traditional synthesis challenges, including high energy consumption, multi-step procedures, and hazardous reagent requirements. The structural and chemical properties of the synthesized TiNCl were characterized through multiple analytical techniques. X-ray diffraction (XRD) patterns confirmed the presence of TiNCl phase, while Raman spectroscopy data showed no detectable oxide impurities. Fourier transform infrared spectroscopy (FTIR) analysis revealed characteristic Ti–N stretching vibrations, further confirming successful titanium nitride synthesis. Transmission electron microscopy (TEM) imaging revealed thin, plate-like nanostructures with high electron transparency. These analyses confirmed the formation of highly crystalline TiNCl flakes with nanoscale dimensions and minimal structural defects. The material exhibits excellent structural integrity and phase purity, demonstrating potential for applications in photocatalysis, electronics, and energy storage. This work establishes FJH as a sustainable and scalable approach for producing MXenes with controlled properties, facilitating their integration into emerging technologies. Unlike conventional methods, FJH enables rapid, energy-efficient synthesis while maintaining material quality, providing a viable route for industrial-scale production of two-dimensional materials.

Physchem doi: 10.3390/physchem5030029

Authors: Marisa Martins Carlos Andrade Amadeu D. S. Borges

This review explores CO2 methanation and steam methane reforming (SMR) as two key thermochemical processes governed by reversible reactions, each offering distinct contributions to carbon-neutral energy systems. The objective is to provide a comparative assessment of both processes, highlighting how reaction reversibility can be strategically leveraged for decarbonization. The study addresses methane production via CO2 methanation and hydrogen production via SMR, focusing on their thermodynamic behaviors, catalytic systems, environmental impacts, and economic viability. CO2 methanation, when powered by renewable hydrogen, can result in emissions ranging from −471 to 1076 kg CO2-equivalent per MWh of methane produced, while hydrogen produced from SMR ranges from 90.9 to 750.75 kg CO2-equivalent per MWh. Despite SMR’s lower production costs (USD 21–69/MWh), its environmental footprint is considerably higher. In contrast, methanation offers environmental benefits but remains economically uncompetitive (EUR 93.53–204.62/MWh). Both processes rely primarily on Ni-based catalysts, though recent developments in Ru-based and bimetallic systems have demonstrated improved performance. The review also examines operational challenges such as carbon deposition and catalyst deactivation. By framing these technologies through the shared lens of reversibility, this work outlines pathways toward integrated, efficient, and circular energy systems aligned with long-term sustainability and climate neutrality goals.

Physchem doi: 10.3390/physchem5030028

Authors: Asma Nouira Imene Bekri-Abbes

Plastic waste and water pollution demand circular economy-driven innovations. This review examines metal–organic framework (MOF) synthesis from polyethylene terephthalate (PET) waste for wastewater treatment. Depolymerized PET yields terephthalic acid and ethylene glycol—essential MOF precursors. We evaluate the following: (1) PET depolymerization (hydrolysis, glycolysis, ammonolysis) for monomer recovery efficiency; (2) MOF synthesis (solvothermal, microwave, mechanochemical) using PET-derived linkers; (3) performance in adsorbing heavy metals, dyes, and emerging contaminants. PET-based MOFs match or exceed commercial adsorbents in pollutant removal while lowering costs. Their tunable porosity and surface chemistry enhance selectivity and capacity. By converting waste plastics into functional materials, this strategy tackles dual challenges: diverting PET from landfills and purifying water. The review underscores the environmental and economic benefits of waste-sourced MOFs, proposing scalable routes for sustainable water remediation aligned with zero-waste goals.

Physchem doi: 10.3390/physchem5030027

Authors: Sang-Un Kim Joo-Yong Kim

Conductive polymer composites (CPCs) filled with anisotropic materials such as carbon nanotubes (CNTs) exhibit electrical behavior governed by percolation through filler networks. While filler volume and shape are commonly studied, the influence of orientation and alignment remains underexplored. This study uses Monte Carlo simulations to examine how the mean orientation angle and angular dispersion of CNTs affect conductive network formation. The results demonstrate that electrical connectivity is highly sensitive to orientation. Contrary to conventional assumptions, maximum connectivity occurred not at 45° but at around 55–60°. A Gaussian-based orientation probability function was proposed to model this behavior. Additionally, increased orientation dispersion enhanced conductivity in cases where alignment initially hindered connection, highlighting the dual role of alignment and randomness. These findings position orientation as a critical design parameter—beyond filler content or geometry—for engineering CPCs with optimized electrical performance. The framework provides guidance for processing strategies that control alignment and supports applications such as stretchable electronics, directional sensors, and multifunctional materials. Future research will incorporate full 3D orientation modeling to reflect complex manufacturing conditions.

Physchem doi: 10.3390/physchem5030026

Authors: José Daniel Sierra Murillo

The research reviews and contrasts two studies based on the gas-phase reaction OH + D2(v, j). In these studies, Quasi-Classical Trajectory (QCT) calculations and the Gaussian Binning (GB) technique were used on the Wu–Schatz–Lendvay–Fang–Harding (WSLFH) potential energy surface. Large sample sizes allow for precise energy state distribution analysis across translational, vibrational, and rotational components in the products. A key observation is the influence of the vibrational and rotational excitation of D2 on the total angular momentum (J′) of the HOD* product. This study reveals that increasing the vibrational level, vD2, significantly shifts P(J′) distributions toward higher values, broadening them due to increased isotropy. In contrast, increasing the rotational level, jD2, results in a smaller shift but introduces greater anisotropy, leading to a more selective distribution of J′ values. The dual Gaussian Binning selection—Vibrational-GB followed by Rotational-GB—further highlights a preference for either odd or even J′ values, depending on the specific excitation conditions. These findings have implications for the development of chemical lasers, as the excitation and emission properties of HOD* can be leveraged in the laser design. Future research aims to extend this study to a broader range of initial conditions, refining the understanding of reaction dynamics in controlled gas-phase environments.

Physchem doi: 10.3390/physchem5030025

Authors: Arash Yahyazadeh

Solid oxide fuel cells (SOFCs) represent a pivotal technology in renewable energy due to their clean and efficient power generation capabilities. Their role in potential carbon mitigation enhances their viability. SOFCs can operate via a variety of alternative fuels, including hydrocarbons, alcohols, solid carbon, and ammonia. However, several solutions have been proposed to overcome various technical issues and to allow for stable operation in dry methane, without coking in the anode layer. To avoid coke formation thermodynamically, methane is typically reformed, contributing to an increased degradation rate through the addition of oxygen-containing gases into the fuel gas to increase the O/C ratio. The performance achieved by reforming catalytic materials, comprising active sites, supports, and electrochemical testing, significantly influences catalyst performance, showing relatively high open-circuit voltages and coking-resistance of the CH4 reforming catalysts. In the next step, the operating principles and thermodynamics of methane reforming are explored, including their traditional catalyst materials and their accompanying challenges. This work explores the components and functions of SOFCs, particularly focusing on anode materials such as perovskites, Ruddlesden–Popper oxides, and spinels, along with their structure–property relationships, including their ionic and electronic conductivity, thermal expansion coefficients, and acidity/basicity. Mechanistic and kinetic studies of common reforming processes, including steam reforming, partial oxidation, CO2 reforming, and the mixed steam and dry reforming of methane, are analyzed. Furthermore, this review examines catalyst deactivation mechanisms, specifically carbon and metal sulfide formation, and the performance of methane reforming and partial oxidation catalysts in SOFCs. Single-cell performance, including that of various perovskite and related oxides, activity/stability enhancement by infiltration, and the simulation and modeling of electrochemical performance, is discussed. This review also addresses research challenges in regards to methane reforming and partial oxidation within SOFCs, such as gas composition changes and large thermal gradients in stack systems. Finally, this review investigates the modeling of catalytic and non-catalytic processes using different dimension and segment simulations of steam methane reforming, presenting new engineering designs, material developments, and the latest knowledge to guide the development of and the driving force behind an oxygen concentration gradient through the external circuit to the cathode.

Physchem doi: 10.3390/physchem5030024

Authors: Ashfaq Ahmad Khan Muhammad Kashif Shahid

Food irradiation is gaining popularity worldwide due to its potential to extend shelf life, improve hygienic quality, and meet trade requirements. The electron paramagnetic resonance (EPR) method is a reliable and sensitive technique for detecting untreated and irradiated foods. This study investigated the effectiveness of EPR in identifying irradiated meat and seafood containing bones. Beef, lamb, chicken, and various fish were irradiated with electron beams at different doses and analysed using an EPR spectrometer. During irradiation, the food samples were surrounded by small ice bags to prevent autodegradation of cells and nuclei. After the irradiation process, the samples were stored at −20 °C. For EPR signal recording, the flesh, connective tissues, and bone marrow were removed from the bone samples, which were then oven-dried at 50 °C. The EPR spectra were recorded using an X-band EPR analyzer. Unirradiated and irradiated samples were identified based on the nature of the EPR signals as well as the g-values of symmetric and asymmetric signals. The study found that the EPR method is effective in distinguishing between unirradiated and irradiated bone-containing foods across nearly all applied radiation doses. The peak-to-peak amplitude of the EPR signals increased with increasing radiation doses. It was observed that unirradiated bone samples showed low-intensity symmetrical signals, while irradiated samples showed typical asymmetric signals. Overall, the study demonstrated that the EPR method is a reliable and sensitive technique for identifying irradiated foods containing bones and can be used for the control, regulation, and proper surveillance of food irradiation.

Physchem doi: 10.3390/physchem5020023

Authors: Samson Okikiola Oparanti Issouf Fofana Reza Jafari

In power transformers, insulating liquids are essential for cooling, insulation, and condition monitoring. However, the environmental impact and biodegradability issues of traditional hydrocarbon-based liquids have spurred interest in green alternatives like natural esters. Despite their benefits, natural esters are highly prone to oxidation, limiting their broader use. This study explores a novel blend of two plant-based oils, canola oil and methyl ester derived from palm kernel oil, enhanced with two antioxidants, Tert-butylhydroquinone (TBHQ) and 2,6-Di-tert-butyl-4-methyl-phenol (BHT), to improve oxidation resistance. The performance of this antioxidant-infused oil was evaluated in terms of its interaction with Kraft paper insulation through accelerated thermal aging over periods of 10, 20, 30, and 40 days. Key properties, including the viscosity, breakdown voltage, conductivity, and FTIR spectra of oils, were analyzed before and after aging. Additionally, the degradation of the Kraft paper was investigated using scanning electron microscopy (SEM), optical microscopy, and dielectric strength tests. The results show that the antioxidant-treated oil exhibits significantly enhanced molecular stability, reduced viscosity, lower conductivity, and improved breakdown voltage (53.16 kV after 40 days). Notably, the oil mixture maintained the integrity of the Kraft paper insulation better than traditional natural esters, demonstrating superior dielectric properties and a promising potential for more sustainable and reliable power transformer applications.

Physchem doi: 10.3390/physchem5020022

Authors: Guilherme S. L. Fabris Mateus M. Ferrer Claudio R. R. Almeida Carlos A. Paskocimas Julio R. Sambrano Felipe A. La Porta

A comprehensive investigation of the chemical bonding, electronic structure, and spectroscopic properties of the lanarkite-type Pb2SO5 (PSO) structure was conducted, for the first time, using density functional theory simulations. Thus, different functionals, PBE, PBE0, PBESOL, PBESOL0, BLYP, WC1LYP, and B3LYP, were used, and their results were compared to predict their fundamental properties accurately. All DFT calculations were performed using a triple-zeta valence plus polarization basis set. Among all the DFT functionals, PBE0 showed the best agreement with the experimental and theoretical data available in the literature. Our results also reveal that the [PbO5] clusters were formed with five Pb–O bond lengths, with values of 2.29, 2.35, 2.57, 2.60, and 2.79 Å. Meanwhile, the [SO4] clusters exhibited uniform S–O bond lengths of 1.54 Å. Also, a complete topological analysis based on Bader’s Quantum Theory of Atoms in Molecules (QTAIM) was applied to identify atom–atom interactions in the covalent and non-covalent interactions of the PSO structure. Additionally, PSO has an indirect band gap energy of 4.83 eV and an effective mass ratio (mh*/me*) of about 0.192 (PBE0) which may, in principle, indicate a low degree of recombination of electron–hole pairs in the lanarkite structure. This study represents the first comprehensive DFT investigation of Pb2SO5 reported in the literature, providing fundamental insights into its electronic and structural properties.

Physchem doi: 10.3390/physchem5020021

Authors: Amina Ghedjemis Maya Kebaili Kamel Hebbache Cherif Belebchouche El Hadj Kadri

The recovery of green waste and biomass presents a significant challenge in the 21st century. In this context, this study aims to valorize waste generated by the fruit juice processing industry at the N’Gaous unit (composed of the orange peel, fibers, pulp, and seeds) as an adsorbent to eliminate an anionic dye and to enhance its adsorption capacity through thermal activation at 200 °C and 400 °C. The aim is also to determine the parameters for the adsorption process including contact time (0–120 min), solution pH (2–10), initial dye concentration (50–700 mg/L), and adsorbent dosage (0.5–10 g/L). The adsorption tests showed that waste activated at 400 °C (AR400) demonstrated a higher efficiency for removing indigo carmine (IC) from an aqueous solution than waste activated at 200 °C (AR200) and unactivated waste (R). The experimental maximum adsorption capacities for IC were 70 mg/g for unactivated waste, 500 mg/g for waste activated at 200 °C, and 680 mg/g for waste activated at 400 °C. These tests were conducted under conditions of pH 2, an equilibrium time of 50 min, and an adsorbent concentration of 1 g/L. The analysis of the kinetic data revealed that the pseudo-second-order model provides the best fit for the experimental results, indicating that this mechanism predominates in the sorption of the pollutant onto the three adsorbents. In terms of adsorption isotherms, the Freundlich model was found to be the most appropriate for describing the adsorption of dye molecules on the R, AR200, and AR400 supports, owing to its high correlation coefficient. Before adsorption tests, the powder R, AR200 and AR400 were characterized by various analyses, including Fourier transform infrared (FTIR), pH zero charge points and laser granularity for structural evaluation. According to the results of these analyses, the specific surface area (SSA) of the prepared material increases with the increase in the activation temperature, which expresses the increase in the adsorption of material activated at 400 °C, compared with materials activated at 200 °C and the raw material.

Physchem doi: 10.3390/physchem5020020

Authors: Kenneth O. Amanze Janet O. Amanze Appolinus I. C. Ehirim Lynda C. Ngozi-Olehi Rosemary I. Uchegbu Glory J. Okore Pamela I. Okeke Christian E. Enyoh

A 3-Amino-Propyl Trimethoxy Silane (APTS) functionalized silica was prepared and investigated. The functionalized silica showed a powerful removal behavior towards Chromium (III) [Cr (III)] and Cadmium (II) [Cd (II)] ions in aqueous solution. Different factors affecting the heavy metal ions adsorption on these substrates such as pH, initial concentration, contact time, and temperature were investigated. FT-IR analyses were carried out to characterize the functionalization of salicylaldehyde unto 3-aminopropyl silica. Results showed that optimum adsorption of the metal ions occurred at a pH of 7 and 6 by the pure silica and functionalized silica, respectively. Removal efficiencies of the adsorbents showed the trend: Salicylaldehyde-APTS modified > pure silica. The adsorption was described by the Langmuir adsorption isotherm. The kinetic results showed that the adsorption was described well with the pseudo second-order kinetic model. The study reveals that both pure silica and functionalized silica can be used as good adsorbents for the removal of the heavy metal pollutants from aqueous solutions and may be applied in the treatment of industrial waste waters, and they may be useful in detoxifying our already polluted environments.

Physchem doi: 10.3390/physchem5020019

Authors: Marjana Simonič

The aim of the study was to investigate the fixation of Cr(VI) ions from contaminated sediments using synthetic zeolite 4A and natural zeolite clinoptilolite. Parameters such as pH, contact time, adsorption mass and temperature were investigated. If the ions of the heavy metals were mobile, they would become toxic to the environment. After sediment digestion, the initial and final concentrations of Cr(VI) were measured in sediment samples with or without zeolite. Inductively coupled plasma with optical emission spectroscopy (ICP-OES) and X-ray diffraction (XRD) were used to characterize the material. The adsorption kinetics were investigated using a pseudo-first order model, a pseudo-second order model, and an intra-particle diffusion model. The results showed that the zeolites enhanced the fixation of Cr(VI). Chemisorption was the main mechanism when using acid-modified zeolite.

Physchem doi: 10.3390/physchem5020018

Authors: Parnia Navabpour Kun Zhang Giuseppe Sanzone Susan Field Hailin Sun

Aluminium is an attractive material for proton-exchange-membrane fuel cell bipolar plates as it has a much lower density than steel and is easier to form than both steel and graphite. This work focused on the development of amorphous carbon films deposited using closed-field unbalanced magnetron sputtering (CFUBMS) in order to improve the corrosion resistance of aluminium bipolar plates and to enhance fuel cell performance and durability. Chromium and tungsten adhesion layers were used for the coatings. It was possible to achieve good electrical conductivity and high electrochemical corrosion resistance up to 70 °C on polished Aluminium alloy 6082 by tuning the deposition parameters. Coatings with a tungsten adhesion layer showed better corrosion resistance than those with a chromium adhesion layer. In situ, accelerated stress testing of single cells was performed using uncoated and coated Al6082 bipolar plates. Both coatings resulted in improved fuel cell performance compared to uncoated aluminium when used on the cathode side of the fuel cell.

Physchem doi: 10.3390/physchem5020017

Authors: Christian Israel Padilla-Hernández Jorge Manuel Silva-Jara Martha Reyes-Becerril Abril Fonseca-García Luis Miguel Anaya-Esparza Paulo Roberto Orozco-Sánchez Juan José Rivera-Valdés Mireille López-Orozco Carlos Arnulfo Velázquez-Carriles María Esther Macías-Rodríguez

This work successfully synthesized green zinc oxide nanoparticles using extracts from strawberry guava leaves (Psidium cattleianum Sabine). Additionally, the reducing effect of the antioxidant extracts obtained through traditional techniques, such as infusion and maceration, was studied and compared against an emerging unconventional technology like ultrasound assisted extraction. Regarding the physical and chemical characteristics, it was found that all three systems were confined within a wavelength range of 357 to 370 nm (UV-vis) and sizes from 60 to 140 nm for the ultrasound-assisted nanoparticles (SEM), corroborated with DLS (134 ± 60 nm). Through X-ray diffraction, the hexagonal wurtzite structure was elucidated, and it was observed that ultrasound favored a higher percentage of crystallinity (98%) compared to the infusion (84%) and maceration (72%). This could be correlated with different functional groups via FTIR and with thermal events associated with thermogravimetric curves, where the total biomass weight loss was lower for nanoparticles using ultrasound extract (6.25%), followed by maceration (15.55%) and infusion (18.01%) extracts. Furthermore, these nanostructures were evaluated against clinically relevant pathogens, including Salmonella enteritidis, Staphylococcus aureus, Escherichia coli O157:H7, and Pseudomonas aeruginosa, assessing bacterial growth inhibition using the microdilution technique, and achieving inhibitions of 75%. Biofilm activity was evaluated through Congo red and crystal violet assays, where ultrasound-derived NPs proved to be good inhibitors for all pathogens. Finally, the toxicity of the nanoparticles was analyzed against peripheral blood leukocytes from goats as well as on the 3 T3-L1 cell line used in anti-obesity assays; the nanoparticles proved to be suitable in all concentrations reaching around 100% cell viability, positioning them as good candidates for diverse industrial applications that align with the principles of green chemistry towards a circular economy.

Physchem doi: 10.3390/physchem5020016

Authors: Yun Shi Lauren A. Blackwell Ryan K. Schroy B. Max Cleland Cristina M. Risi Michelle S. Parvatiyar Jose R. Pinto Vitold E. Galkin P. Bryant Chase

Troponin C (TnC) is the Ca2+-sensing subunit of troponin that is responsible for activating thin filaments in striated muscle, and, in turn, for regulating the systolic and diastolic contractile function of cardiac muscle. The secondary structure of vertebrate TnC is mainly composed of α-helices, with nine helices named sequentially, starting from the amino terminus, from N to A–H. The N-helix is a 12-residue-long α-helix located at the extreme amino terminus of the protein and is the only helical structure that does not participate in forming Ca2+-binding EF-hands. Evolutionarily, the N-helix is found only in TnC from mammalian species and most other vertebrates and is not present in other Ca2+-binding protein members of the calmodulin (CaM) family. Furthermore, the primary sequence of the N-helix differs between the genetic isoforms of the fast skeletal TnC (sTnC) and cardiac/slow skeletal TnC (cTnC). The 3D location of the N-helix within the troponin complex is also distinct between skeletal and cardiac troponin. Physical chemistry and biophysical studies centered on the sTnC N-helix demonstrate that it is crucial to the thermal stability and Ca2+ sensitivity of thin filament-regulated MgATPase activity in solution and to isometric force generation in the sarcomere. Comparable studies on the cTnC N-helix have not yet been performed despite the identification of cardiomyopathy-associated genetic variants that affect the residues of cTnC’s N-helix. Here, we review the current status of the research on TnC’s N-helix and establish future directions to elucidate its functional significance.

Physchem doi: 10.3390/physchem5020015

Authors: Lukas Boden Faras Brumand-Poor Linda Pleninger Katharina Schmitz

Bio-hybrid fuels, chemically derived from sustainable raw materials and green energies, offer significant potential to reduce carbon dioxide emissions in the transport sector. However, when these fuels are used as drop-in replacements in internal combustion engines, material compatibility with common sealing materials is not always given. Within the cluster of excellence, “The Fuel Science Center (FSC)” at RWTH Aachen, experimental immersion tests were conducted on a limited set of fuel and sealing material combinations. Given the extensive range of possible fuel and sealing combinations, a data-based machine learning prediction framework was developed and validated to pre-select promising fuel candidates. Due to the limited number of samples, preliminary results indicate a need to expand the database. Since experimental investigations are time-consuming and costly, this work explores faster physics-motivated data generation approaches by modeling molecular interactions between fuel and sealing materials. Two modeling scales are employed. One calculates the intermolecular distance using density functional theory. The other uses Hansen solubility parameters, representing an abstract modeling of intermolecular forces. Both approaches are compared, and their limitations are assessed. Including the generated data in the prediction framework improves its accuracy.