Search Results (164)

Ultra-lean hydrogen flames under terrestrial gravity are governed by a coupled interaction among preferential diffusion, thermal diffusion, heat loss, and self-induced convection. This study numerically examines combustion in a quiescent 6 vol.% H₂–air mixture using detailed chemistry and a low–Mach–number formulation. A complete set of calculations was considered, with Soret diffusion and optically thin radiative heat loss independently enabled and disabled. One-dimensional spherical calculations were used to isolate the initial post-ignition flame kernel growth, while two-dimensional planar and axisymmetric simulations described its subsequent buoyant rise, deformation, and breakup. Over the analyzed interval, the spherical flame-front radius followed an extended $R_f^2\approx Kt$ regime rather than constant-speed expansion. Soret diffusion increased the effective growth coefficient K, whereas radiation reduced it. The axisymmetric calculations reproduced the experimentally measured leading-point trajectory substantially better than the planar formulation. Soret diffusion produced larger, faster-rising kernels and maintained a more nearly circular upper cap, whereas radiation had a weaker effect on trajectory but increased relative lateral flattening. In all cases, a toroidal vortex stretched the flame segment and caused local extinction and fragmentation. Soret diffusion delayed breakup, while radiation advanced it; their combined effect on breakup time was nearly compensating. The results show that Soret transport and radiation primarily alter kernel growth and resistance to vortex-induced extinction, while the qualitative breakup pathway remains hydrodynamically controlled. Full article

The nephrotoxicity and ototoxicity of Gentamicin have been extensively investigated; however, whether they induce hematotoxicity remains unclear. This study aimed to explore the binding of Gentamicin to adult hemoglobin (HbA) and its toxicological implications. The effect of Gentamicin on HbA oxidation was assessed by quantifying methemoglobin (MetHb) formation via a four-wavelength spectrophotometric method, and scavenger rescue assays were employed to elucidate the oxidative mechanism. Alterations in the oxygen-carrying capacity of both HbA and RBCs were evaluated through the acquisition of oxygen equilibrium curves and oxygen dissociation assays. The binding affinity between Gentamicin and HbA was determined by surface plasmon resonance (SPR). Furthermore, the influence of Gentamicin on the secondary and tertiary structures of HbA was examined by microfluidic modulation spectroscopy (MMS) and UV–visible absorption spectroscopy, respectively. Molecular docking was employed to predict the binding sites of Gentamicin on HbA. Molecular dynamics simulations verified the stability of the binding. Gentamicin promoted HbA autoxidation, elevating MetHb levels, and reduced the oxygen affinity of HbA. Gentamicin-promoted HbA autoxidation is primarily mediated by both direct heme-pocket perturbation and H₂O₂/iron-dependent amplification. SPR confirmed concentration-dependent specific binding between Gentamicin and HbA. MMS indicated no alteration in HbA secondary structure; however, UV–visible spectroscopy revealed that Gentamicin attenuated the Soret band, converted the oxyhemoglobin double-peak to a singlet, and generated a new band at 630 nm. Molecular docking predicted that Gentamicin binds β-chain residues via hydrogen, carbon–hydrogen, and hydrophobic interactions. This study reveals that Gentamicin exerts hematological effects in vitro. By binding to specific sites on HbA, Gentamicin affects the tertiary structure of HbA, promotes heme oxidation, ultimately increases MetHb content (oxidative damage), and decreases its oxygen-carrying capacity (functional impairment). Full article

During the preparation of silicon carbide (SiC) thin films by chemical vapor deposition (CVD), the Soret effect induced by a large temperature gradient influences the deposition rate and uniformity; its sensitivity to process parameters remains unclear. A computational fluid dynamics model coupling detailed gas-phase and surface reaction kinetics was developed and validated for a cold/warm wall vertical CVD reactor. Comparing simulations with and without the thermal diffusion term reveals the dual role—suppressing deposition rate while degrading film uniformity. The thermal diffusion contributions to deposition rate (TDC_GR) and uniformity (TDC_GU) are introduced as quantitative metrics, and simulations evaluated the effects of inlet–substrate temperature difference (ΔT), reactor pressure (p), substrate rotation speed (ω), and carrier gas flow rate (Q) on the Soret effect, clarifying optimal conditions. Results show ΔT dominates. At ΔT = 1700 K, TDC_GR = −56.39% and TDC_GU = 5.29%. Pressure affected TDC_GR negligibly but significantly reduced TDC_GU by enhancing gas-phase mixing; increasing p from 7500 to 12,500 Pa led to a decrease in TDC_GU from 4.19% to 1.93%. Optimal parameters (ΔT = 1400 K, p = 12,500 Pa, ω = 800 rpm, Q = 50 slm) achieved a deposition rate of 10.71 μm/h and non-uniformity of 0.45%. These findings provide theoretical guidance for precise SiC-CVD process control in cold- or hot-wall vertical reactor architectures. Full article

This paper presents fully transient analytical solutions for organic contaminant transport through composite liner systems consisting of a geomembrane (GMB) underlain by either a compacted clay liner (CCL) or a geosynthetic clay liner (GCL). The proposed solutions simultaneously account for three key mechanisms, namely advection due to GMB defects and wrinkles, first-order degradation, and thermodiffusion induced by temperature gradients. The solutions provide steady-state temperature distribution, transient contaminant concentration profiles, mass flux, and cumulative mass outflow at the base of the liner. The analytical solutions are rigorously verified against experimental thermodiffusion data from the literature, an existing analytical solution, and a numerical model using COMSOL Multiphysics 5.4. A parametric study is conducted to investigate the effects of thermodiffusion, Soret coefficient, and thermal conductivity on benzene transport. Results show that thermodiffusion substantially increases benzene outflow; neglecting it may lead to unconservative liner design. The benzene transport rate increases almost linearly with the Soret coefficient. The thermal conductivity of the GMB and GCL significantly affects benzene transport in the GMB/GCL system, while the thermal conductivities of the GMB and CCL have negligible effects on the GMB/CCL system. The proposed analytical solutions enable rapid parametric analysis, preliminary liner design, environmental risk assessment, and early warning. By enabling rapid comparison of GMB/CCL versus GMB/GCL systems (material selection), optimization of clay layer thickness for required breakthrough time (thickness optimization), and quantification of thermal effects on contaminant flux (temperature control), the solutions serve as an efficient tool for sustainable liner design. Full article

The present computational work investigates the effects of thermal radiation, activation energy, and diffusion-thermo (Dufour) and thermo-diffusion (Soret) effects on 3D doubly diffusive convective rotational streams across a surface contained in a non-Darcian porous structure. The dominating mathematical system is converted into a group of ODEs (ordinary differential equations) by appropriate similarity transformations. The non-dimensional model is solved using the fourth-order Runge–Kutta method with a shooting procedure numerically. For the fields of concentration, temperature, and velocity, the findings are shown visually. The local heat and mass transport rates are given by computed Sherwood and Nusselt numbers. By growing the values of radiation, activation energy parameters, and Soret number, the local rate of heat transfer increases. Nevertheless, as the Soret and activation energy parameter values increase, the mass transfer decreases. The outcome of the present research can be used to model thermal systems. Full article

Background/Objectives: The increased prevalence of multidrug-resistant Escherichia coli and carbapenemase-producing Enterobacteriaceae poses a critical threat to global health and food safety. Antimicrobial Blue Light (aBL) in the 400–470 nm spectrum has emerged as a promising, chemical-free disinfection strategy that targets intracellular porphyrins and flavins to induce oxidative stress. However, the influence of wavelength, dosimetry, and environmental stressors on endogenous photoinactivation remains poorly standardized regarding optical parameters and biological exposure protocols. This systematic review aimed to evaluate the antimicrobial efficacy of pure blue light (400–470 nm) against E. coli across various phenotypes and environmental conditions, excluding the use of exogenous photosensitizers. Methods: PubMed, Scopus, and Web of Science were searched for studies that utilized 400–470 nm light as an antimicrobial agent against E. coli. Data extraction focused on spectral efficiency, total fluence (J/cm²), and log₁₀ reduction. The Risk of Bias was assessed using an adapted Office of Health Assessment and Translation tool for in vitro studies. Results: Synthesis of 11 high-quality studies indicated that wavelengths near 405 nm have the highest germicidal efficiency due to the Soret band absorption of endogenous porphyrins. Efficacy is highly dose-dependent: significant log₁₀ reductions were achieved in planktonic cells, although biofilms required substantially higher fluences. Sub-lethal environmental stressors such as acidic pH, high salinity, and thermal fluctuations demonstrated a synergistic effect, which significantly enhanced the rate of photoinactivation. Multidrug-resistant and carbapenemase-producing Enterobacteriaceae strains showed similar susceptibility to aBL relative to antibiotic-sensitive strains, suggesting no cross-resistance between light and traditional drugs. Conclusions: Endogenous blue light is a highly effective, non-thermal technology for E. coli decontamination. Its efficacy is modulated by the interplay between optical parameters and environmental conditions. These findings provide a framework for the development of standardized protocols for applying aBL to clinical wound care and food industry use cases. They also highlight the potential of aBL as a critical tool in the post-antibiotic era. This systematic review was registered in the International prospective register of systematic reviews (PROSPERO) under protocol CRD420261331871. Full article

The growing demand for accurate and timely Earth observation (EO) data has made autonomous mission planning increasingly essential. In particular, data acquisition planning has gained attention in recent years with the advent of agile Earth observation satellites (AEOSs). This process involves two main stages: target identification and observation scheduling. Traditionally, the former is performed manually, while the latter requires solving the agile Earth observation satellite scheduling problem (AEOSSP), a complex combinatorial optimization problem. In this work, we propose a constellation design comprising EO satellites deployed in medium Earth orbit (MEO) and low Earth orbit (LEO). The MEO satellites acquire low-resolution (LR) images for onboard target identification and subsequently schedule high-resolution (HR) observations by a set of LEO AEOSs. We adapt the AEOSSP to this multi-orbit context by explicitly considering communication constraints between MEO and LEO satellites and propose several heuristic solution methods. Among them, the quality-based greedy algorithm yields up to a 35.5% improve in observation profit in simple, low-conflict scenarios, while the structured heuristic algorithm proves the most robust, achieving up to a 21.5% increase in challenging schedules. Full article

The DIGIT experiment was launched at the Tournemire Underground Research Laboratory (URL) with the aim of determining the effects of temperature on the transfer of tracers mimicking the most mobile radionuclides in the Toarcian clay rock. The properties of this rock are similar to those of the host rocks being considered for a future deep geological repository for high-level radioactive waste (HLW). The experiment involves the monitoring of the interaction between a test water doped with stable halides and deuterium at constant concentration, and the porewater of the Toarcian clay rock under constant ambient conditions, as well as at higher temperature induced by artificial heating. This experiment seeks to partially address questions regarding the potential spread of contaminants during the thermal phase of HL waste packages. Specifically, the in situ experiment aims to evaluate the role of scale effects, thermodiffusion, a process that combines Fick’s law, the Soret effect, and convection in the transfer of radionuclides. This paper is the second part of a companion paper dedicated to predictive calculations and the installation of the experimental device. It presents the main experimental and modeling results obtained since the beginning of the installation and after 20 months of heat at 70 °C. The test was carried out in five phases, finishing with a sampling campaign: a phase 0 called “initial conditions”, followed by a pure diffusion phase (5 months), then three phases in a heated period lasting 1 year and 8 months. In total, 47 rock cores were analyzed, with approximately 170 samples tested by four diffusion methods (radial, outgoing, through and in vapor-phase) to determine the tracer concentrations in the porewater, their water content and their diffusive transport parameters. The results show a decrease in tracer concentrations with distance from the test zone, in the directions parallel and perpendicular to the stratification. The anisotropy of the medium results in greater migration in the direction parallel to the stratification. Thermal properties also confirm anisotropy with a higher thermal conductivity in the direction parallel to the stratification. Finally, an activation energy of 22.9 ± 1.7 kJ·mol⁻¹ could be proposed by NMR for deuterium, indicating diffusion behavior following an Arrhenius law between 30 and 70 °C. The experimental data allowed for the calibration of a 2D axisymmetric numerical model using the commercial finite element software COMSOL Multiphysics^®. The Fick’s law corrected by an Arrhenius law best reproduces the penetration of deuterium and anions. The Soret effect, integrated into certain scenarios, is only significant for anions’ migration, using a fitted Soret coefficient of 0.1 K⁻¹, as proposed in the literature for the Callovo-Oxfordian, the host rock of the Cigéo project in the east of France. The calibration of the simulated data with the experimental data allowed for the characterization of damaged and/or disturbed zones evolving over time. Simulations over 150 years, the duration of the thermal maximum for HLW packages, show that advection—modeled by Darcy’s law—would have a negligible role in this context due to the low permeability of the upper Toarcian. In conclusion, the DIGIT test showed that, for the Upper Toarcian clay rocks at the Tournemire URL in France, diffusion, corrected for the effect of temperature, is the mechanism that characterizes the transport of radionuclide analogues. The study showed that thermodiffusion has a limited influence on deuterium migration but remains significant for anions in the case of a coupling between temperature correction and thermodiffusion. The test also highlighted the impact of temperature on the spatiotemporal development of a damaged and/or disturbed zone. These new and relevant results in the field will need to be confirmed later through additional experiments. Full article

Enzymatically crosslinked hydrogels are important in biomedical applications. However, conventional horseradish peroxidase (HRP)-based systems are expensive, unstable, and potentially immunogenic. Herein, we introduce hemin/albumin complexes as cost-effective and biocompatible catalysts for phenol-mediated hydrogel formation. Phenolated bovine serum albumins (BSA-LPh, -MPh, and-HPh) with different degrees of substitution were synthesized and complexed with hemin. Spectroscopic analysis demonstrated that phenol modification altered the hemin microenvironment, resulting in distinct shifts in the Soret band. Functional assays revealed that albumin complexation enhanced catalytic activity compared to hemin alone. Moderate phenol modification provided an optimal balance between catalytic efficiency and hydrogel integration, whereas excessive modification reduced the performance of the enzyme. Hydrogels containing hemin/BSA-Ph complexes exhibited controllable protein retention and high cytocompatibility (>90%) with mouse fibroblast 10T1/2 cells. These findings demonstrate that hemin/albumin complexes are promising, cost-effective, and cytocompatible alternatives to HRP systems for hydrogel-based biomedical and nonclinical applications. Full article

Rhodium–porphyrin complexes are characterised by their ability to activate C-H and C-C bonds and, therefore, find applications in synthesis and catalysis. Axial rhodoporphyrin ligands are susceptible to photodissociation under the influence of light. DFT and TDDFT calculations were performed to investigate the mechanism of photodissociation of the methyl ligand from the methylrhodium(III)–porphyrin complex (MeRhPor). Various photolysis pathways of the rhodium–methyl bond were investigated, including photolysis from states in the Q and Soret bands. Photolysis from triplet states was also considered. Based on the calculations, the most probable mechanism for photodissociation of the methyl ligand was proposed. The methyl-rhodium binding energy in the methylrhodium(III)–porphyrin complex and the energy of formation of the rhodium–porphyrin radical dimer formed by methyl dissociation were also calculated. Full article

The search for artificial blood substitutes that are suitable for safe transfusion in clinical conditions and in extreme situations has gained increasing interest during recent years. Most of the problems related to donor blood could be overcome with hemoglobin sub-micron particles (HbMPs) that are able to bind and deliver oxygen. On the other hand, the length of the circulation time of HbMPs in the bloodstream strongly depends on their surface properties and can be improved with biopolymer coatings. The redox potential of HbMPs and HbMPs coated with biopolymers using the layer-by-layer technique (LbL-HbMPs) is related to the energy required for electron transfer upon transition from an oxidized to a reduced state. It can be used as a measure of the stability of Hb against oxidation, which is directly connected with its function as an oxygen carrier. The redox potential of Hb, HbMPs, and LbL-HbMPs was determined by a spectroelectrochemical method utilizing the shift of the Soret peak of Hb upon oxidation/reduction of the iron in the heme. The obtained results showed a slight shift in the redox potential of both particle types of about 17 mV towards more negative values compared to the free Hb in the solution. It was demonstrated that the free Hb and the cross-linked Hb in HbMPs and LbL-HbMPs undergo transitions from an oxidized to a reduced state and vice versa several times without Hb destruction. The LbL coating does not affect the redox properties of HbMPs. This ability, as well as the proximity of the obtained redox potentials of Hb, HbMPs, and LbL-HbMPs, indicates that the eventual oxidation of HbMPs in the bloodstream is reversible; thus, HbMPs can be active as artificial oxygen carriers for a longer period of time. Full article

This work presents the synthesis, characterization and evaluation of physicochemical and biological properties of two new aminoporphyrazine derivatives bearing magnesium(II) cations in their cores and peripheral pyrrolyl groups. The synthesis was carried out in several stages, using classical methods and the Microwave-Assisted Organic Synthesis (MAOS) approach. The obtained compounds were characterized using spectral techniques: UV-Vis spectrophotometry, mass spectrometry, ¹H and ¹³C NMR spectroscopy. The porphyrazine derivatives were tested for their electrochemical properties (CV and DPV), which revealed four redox processes, of which in compound 7 positive shifts of oxidation potentials were observed, resulting from the presence of free phenolic hydroxyl groups. In spectroelectrochemical measurements, changes in UV-Vis spectra associated with the formation of positive-charged states were noted. Photophysical studies revealed the presence of characteristic absorption Q and Soret bands, low fluorescence quantum yields and small Stokes shifts. The efficiency of singlet oxygen generation (Φ_Δ) was higher for compound 6 (up to 0.06), but compound 7, despite its lower efficiency (0.02), was distinguished by a better biological activity profile. Toxicity tests using the Aliivibrio fischeri bacteria indicated the lower toxicity of 7 compared to 6. The most promising result was the strong photodynamic activity of porphyrazine 7 against the Methicillin-resistant Stapylococcus aureus (MRSA) strain, leading to a more-than-5.6-log decrease in viable counts after the colony forming units (CFU) after light irradiation. Compound 6 did not show any significant antibacterial activity. The obtained data indicate that porphyrazine 7 is a promising candidate for applications in photodynamic therapy of bacterial infections. Full article

The Second Law of Thermodynamics states that entropy S increases in a spontaneous process in an ideal isothermal and isolated system. Real systems are influenced by external forces and fields, including the temperature field. In this case, only entropy is not enough, and we suggest using a new function, $L_s$, which is analogous to the Lagrangian in classical mechanics. It includes total potential energy but instead of mechanical kinetic energy, $L_s$ includes the product ST, and the system always evolves towards increasing this modified Lagrangian. It reaches an equilibrium when total potential force is balanced by both entropic and thermal forces. All forces have the same units, Newton/mol, and may be added or subtracted. For condensed systems with friction forces, it is a molecular transport velocity, and not acceleration, which is proportional to the acting force. Our approach has several advantages compared to Onsager’s non-equilibrium thermodynamics with its thermodynamic forces, which may have different units, including 1/T for energy transport. For isolated systems, the description is reduced to Second Law and Clausius inequality. It easily explains diffusion, Dufour effect, and Soret thermodiffusion. The combination of electric, thermal, and entropic forces explains thermoelectric phenomena, including Peltier–Seebeck and Thomson (Lord Kelvin) effects. Gravitational and entropic forces together inside a black hole may lead to a steady state or the black hole evaporation. They are also involved in and influenced by solar atmospheric processes. Full article

This study investigates magnetohydrodynamic (MHD) heat and mass transport in a water-based ternary hybrid nanofluid flowing past an exponentially accelerated vertical porous plate. Two critical scenarios are analyzed: (i) uniform heat flux with variable mass diffusion and (ii) varying heat source with constant species diffusion. The model integrates thermal radiation, heat sink/source, thermal diffusion, and chemical reaction effects to assess flow stability and thermal performance. Governing equations are non-dimensionalized and solved analytically using the Laplace transform method, with results validated against published data and finite difference method outcomes. Ternary hybrid nanofluids exhibit a significantly higher Nusselt number compared to hybrid and conventional nanofluids, demonstrating superior heat transfer capabilities. Magnetic field intensity reduces fluid velocity, while porosity enhances momentum transfer. Thermal radiation amplifies temperature profiles, critical for energy systems. Concentration boundary layer thickness decreases with higher chemical reaction rates, optimizing species diffusion. These findings contribute to the development of advanced thermal management systems, such as solar energy collectors and nuclear reactors, enhance energy-efficient industrial processes, and support biomedical technologies that require precise heat and mass control. This study positions ternary hybrid nanofluids as a transformative solution for optimizing high-performance thermal systems. Full article

Porphyrins are highly conjugated macrocyclic compounds that possess exceptional photophysical and chemical properties, progressively establishing themselves as versatile tools in the structural investigation of biomolecules. This review explores their role as chiroptical conformational probes, focusing on their interactions with DNA and RNA. The planar electron rich structure of porphyrin macrocycle that promote π–π interactions, their easy functionalization at the meso positions, and their capacity to coordinate metal ions enable their use in probing nucleic acid structures with high sensitivity. Emphasis is placed on their induced circular dichroism (ICD) signals in the Soret region, which provide precise diagnostic insights into binding mechanisms and molecular interactions. The review examines the interactions of porphyrins with various DNA structures, including B-, Z-, and A-DNA, single-stranded DNA, and G-quadruplex DNA, as well as less common structures like I-motif and E-motif DNA. The last part highlights recent advancements in the use of porphyrins to probe RNA structures, emphasizing binding behaviors and chiroptical signals observed with RNA G-quadruplexes, as well as the challenges in interpreting ICD signals with other RNA motifs due to their inherent structural complexity. Full article