Search Results (805)

The oxygen reduction reaction (ORR) is a pivotal electrochemical process in energy technologies and in the generation of hydrogen peroxide (H₂O₂), which serves as both an effective agent for dye degradation and a fuel in H₂O₂-based fuel cells. In this regard, a titanium (Ti) sheet was anodized to generate a TiO₂ layer, and then the oxide layer was modified with gold (presented as Au/TiO₂/Ti) via electrodeposition. The developed electrocatalyst was confirmed by X-ray photoelectron spectroscopy (XPS), which showed characteristic binding energies for Ti⁴⁺ in TiO₂ and metallic Au. In addition, the Nyquist plot verified the electrode modification process, since the diameter of the semicircular arc, corresponding to charge transfer resistance, significantly decreased due to Au deposition. Voltametric studies revealed that the TiO₂ layer with a Ti surface exhibited a good synergistic effect on Au and the ORR in a bicarbonate medium (0.1 M KHCO₃) by lowering the overpotential, enhancing current density, and boosting durability. The scan rate-dependent study of the ORR produced by the developed electrocatalyst showed a Tafel slope of 180 ± 2 mV dec⁻¹ over a scan rate range of 0.05–0.4 V s⁻¹, thereby indicating a 2e⁻ transfer process in which the initial electron transfer process was the rate-limiting step. The study also revealed that the Au/TiO₂/Ti electrode caused oxygen electro-reduction with a heterogenous rate constant (k⁰) of $4.40\times {10}^{-3}$ cm s⁻¹ at a formal potential (E⁰′) of 0.54 V vs. RHE. Full article

The article describes innovative procedures for determining In(III) using anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (AdSV) with cupferron as a chelating agent. In both procedures, an environmentally friendly solid bismuth microelectrode (SBiµE) with a diameter of 25 µm was used as the working electrode. In both procedures, 0.1 mol L⁻¹ acetate buffer with a pH of 3.0 ± 0.05 was used as the supporting electrolyte. The electrochemical measurement conditions were as follows: −2.4 V for a 20 s activation step and −1.2 V for a 20 s accumulation step for ASV, and −2.5 V for a 45 s activation step and −0.65 V for a 10 s accumulation step for AdSV. The signal was recorded as a result of a positive potential change from −1.0 to −0.3 V in the case of the ASV procedure and as a result of a negative potential change from −0.4 to −1.0 V in the case of the AdSV procedure. The calibration graph was linear from 5 × 10⁻⁹ mol L⁻¹ to 5 × 10⁻⁷ mol L⁻¹ with a detection limit of 1.4 × 10⁻⁹ mol L⁻¹ for ASV and from 1 × 10⁻⁹ mol L⁻¹ to 1 × 10⁻⁷ mol L⁻¹ with a detection limit of 3.9 × 10⁻¹⁰ mol L⁻¹ for AdSV. The effect of interferents such as surfactants, humic substances and EDTA on the analytical signal was compared in the case of signal recording using the ASV technique with the signal recorded using the AdSV technique. Based on the results obtained, it was determined how the charge of interferents affects the signal depending on the technique used. To validate the practical application of the developed procedures, an analysis of In(III) recovery from samples of the Baltic Sea and Synthetic Sea Water was performed. Full article

Supercapacitors are limited by electrolyte cation desolvation, which directly impacts ion storage efficiency and capacitance. This study uses density functional tight-binding (DFTB+) first-principles calculations to investigate the desolvation of bispyrrolidinium cation complexes ([SBP(AN)]⁺, acetonitrile as solvent) in pristine (FP) and oxygen-functionalized (OFP: hydroxyl-HFP, carbonyl-CFP, aldehyde-AFP) bilayer graphene flat pores with AA/AB stacking. Critical desolvation diameters were determined: 5.0 Å (FP), 5.2 Å (HFP), 5.0 Å (AFP), and 4.6 Å (CFP). Hydroxyl functionalization expanded the critical diameter, reduced SBP⁺ intercalation energy, and increased relative capacitance by 1.02~1.03 times; carbonyl groups had the opposite effect, while aldehyde groups showed no significant impact. Density of States (DOS) analysis revealed enhanced conductivity for HFP and AFP after SBP⁺ embedding, but reduced conductivity for CFP. Charge density difference and Bader charge analysis confirmed electron transfer primarily between SBP⁺ (electron donor) and oxygen atoms in functional groups (electron acceptor), with SBP⁺ interacting mainly with functional groups rather than the carbon basal plane. This work provides theoretical guidance for optimizing graphene-based supercapacitor electrodes via pore structure and surface functionalization. Full article

Background/Objectives: The rapid emergence of antibiotic-resistant oral pathogens has rendered many conventional therapies increasingly ineffective. Antimicrobial peptides (AMPs) have emerged as a promising therapeutic alternative due to their unique mechanisms of action and low propensity for inducing resistance. The delivery of novel therapeutic AMPs against oral cavity bacterial infections requires effective pharmaceutical dosage formulations. This study investigated the potential of two liposomal formulations for the association and delivery of the antimicrobial peptide (AMP) LL17-32 against the dental bacterial pathogen Porphyromonas gingivalis. Methods: Liposomes composed of either negatively charged soya lecithin (SL) or neutrally charged dioleoyl-phosphatidylcholine (DOPC) phospholipids were formulated and characterized based on their hydrodynamic size distribution, ζ-potential, morphology, membrane fluidity, peptide association efficiency, stability and release of peptide in vitro under physiological conditions. The characterization of their biological activity included efficiency of bacterial killing, bacterial adherence, and mammalian cell cytotoxicity using human gingival keratinocyte (TIGK) cells. Results: Both liposomal formulations exhibited spherical morphology with hydrodynamic diameters smaller than ~170 nm and demonstrated good colloidal stability. LL17-32 showed high association efficiency with both liposomal membranes, with no detectable LL17-32 in vitro release. In biological assays, peptide-loaded DOPC liposomes exhibited dose-dependent bactericidal activity against P. gingivalis, whereas SL liposomes significantly attenuated the bactericidal effect of LL17-32. Both formulations displayed reduced cytotoxicity toward human gingival keratinocyte (TIGK) cells versus free peptide. Conclusions: These findings suggest that DOPC liposomes represent a promising delivery system for LL17-32 by adhering to P. gingivalis and exhibiting minimal cytotoxicity to mammalian cells. This study emphasises the critical role of lipid charge in designing AMP delivery systems for antibacterial applications, while it additionally demonstrates the utility of flow cytometry as a quantitative tool to assess liposome–bacteria association. Full article

This study investigates the combustion process in a marine spark-ignition engine fueled with an ammonia–hydrogen blend (15% hydrogen by volume) using a passive pre-chamber. A 3D-CFD model, supported by a 1D engine model, was employed to analyze equivalence ratios between 0.7 and 0.9 and pre-chamber nozzle diameters from 7 to 3 mm. Results indicate that combustion is consistently initiated by turbulent jets, but at an equivalence ratio of 0.7, the charge combustion is incomplete. For lean mixtures, reducing nozzle size improves flame propagation, although not sufficiently to ensure stable operation. At an equivalence ratio of 0.8, reducing the nozzle diameter from 7 to 5 mm advances CA50 by about 6 CAD, while further reduction causes minor variations. At richer conditions, nozzle diameter plays a negligible role. Optimal performance was achieved with a 7 mm nozzle at equivalence ratio 0.8, delivering about 43% efficiency and 1.17 MW per cylinder. Full article

Growing concern over nanoplastics as emerging pollutants calls for effective treatment methods, with advanced oxidation processes (AOPs) showing strong potential for their degradation. This study examines the interaction between polyethylene terephthalate nanoplastics (PET-NPs) and magnetite nanoparticles (MNPs) in a heterogeneous Fenton-like system, focusing on colloidal behavior, hydroxyl radicals (^●OH) generation, and potential degradation pathways. Zeta potential (ZP) and particle diameter measurements were used to characterize nanoparticle dispersion and aggregation mechanisms over a pH range of 3–9.5. The results revealed a pronounced pH-dependent stability, with MNPs exhibiting larger hydrodynamic diameters (283 nm) and lower stability at pH 3 (ZP: −9.8 mV) compared with neutral or alkaline conditions (189 nm; ZP: −44 to −42 mV). PET-NPs exhibited minimal agglomeration at a pH of 9.5 (ZP: −25.6 mV). Unlike conventional Fenton systems, ^●OH production peaked at pH 7–9.5 (0.3–0.35 μM), attributed to preserved Fe²⁺ sites and reduced particle agglomeration. Although PET-NPs resisted oxidative degradation, their aggregation with MNPs enabled magnetic recovery (46% efficiency at pH 3) through charge screening, Fe³⁺/Fe²⁺ bridging, and hydrophobic interactions. These findings highlight MNPs’ potential for sustainable nanoplastic separation and emphasize the need for optimized catalysts to enhance ^●OH-driven degradation. Overall, this work advances understanding of nanoplastic–magnetite interactions and offers insights into AOP applications. Full article

In this work, we investigated the use of a piezoelectric flexible device for energy harvesting. The main goal of the study was to fill the nanostructured pores of anodic aluminum oxide (AAO) films with piezoelectric polymer (PVDF-TrFE) via a modified conventional screen printing technique using blade printing. In this way, it is possible to obtain a composite from nanostructured thin films of polymer nanorods that shows improved charge generation ability compared to other non-nanostructured composites or pure (non-composite) aluminum with similar dimensions. This behavior is due to the effect of the highly developed surface of the material used to fill in the AAO nanopore template and its ability to withstand the application of higher mechanical loads to the structured piezoelectric material during deformation. The contact blade print filling technique can produce nanostructured piezoelectric polymer films with precise geometric parameters in terms of thickness and nanorod diameters, at around 200 nm, and a length of 12 μm. At a low frequency of 17 Hz, the highest root-mean-square (RMS) voltage generated using the nanostructured AAO/PVDF-TrFE sample with aluminum electrodes was around 395 mV. At high frequencies above 1700 Hz, the highest RMS voltage generated using the nanostructured AAO/PVDF-TrFE sample with gold electrodes was around 680 mV. The RMS voltage generated using a uniform (non-nanostructured) layer of PVDF-TrFE was 15% lower across the whole frequency range. Full article

This paper presents a novel batch Forward Osmosis (FO) process for hydropower generation. It focuses on analyzing the parameters needed to make the proposed osmotic power plant implementable with currently available technology. Starting from the solution–diffusion model and using flow and mass balance equations, the equations that describe the behavior of the system over time are obtained. Membrane orientation, concentration polarization, reverse solute flux, and membrane fouling are not considered. The equations for calculating the operation time for the charging and discharging stages are obtained. Also, an equation for calculating the required membrane area to make the duration of the two stages the same is obtained. The results indicate that a volume of approximately $30.4 {\mathrm{m}}^3$ discharging through a $0.84 \mathrm{i}\mathrm{n}\mathrm{c}\mathrm{h}$ diameter outflow jet towards a turbine could generate an energy of $25 \mathrm{k}\mathrm{w}·\mathrm{h}.$ The discharging stage would take $12 \mathrm{h}$, and with a membrane with a water permeability constant $A_m=1.763·{10}^{-12} \mathrm{m}/(\mathrm{s}·\mathrm{P}\mathrm{a})$, the charging stage would require a membrane superficial area ${Ar}_m=1·{10}^4 {\mathrm{m}}^2$ to have the same duration. The proposed osmotic power plant, whose working principle is based on volume change over time, contrary to pressure retarded osmosis, whose working principle requires expending energy to extract energy from the salinity gradient, could deliver greater net produced energy with comparatively lower operational costs as it does not require high-pressure pumps or energy recovery devices as are required in pressure-retarded osmosis. The use of several tanks that charge and discharge alternatively can make the system generate energy as if it were a continuous process. Full article

The use of saponins with biosurfactant, antioxidant, anti-inflammatory, and anti-cancer properties is limited by their toxicity and bioavailability. This study focused on the fabrication, characterization, and bioactivity of crude tea saponin (TS) and TS-incorporated silica nanoparticles (TSNPs). Our results showed that TS contained seven saponins and that TSNPs had an average diameter of 200–300 nm, a negative surface charge, and high polydispersity. Fourier Transform Infrared Spectroscopy (FTIR) revealed an incorporation bond of Si-O- and -OH controlling releasing behavior with t₅₀ = 24 h. Using HaCaT cells, it was demonstrated that TSNPs reduced cytotoxicity. Reactive oxygen species (ROS) production was lowered in both TS and TSNP treatments, with significantly greater efficacy at higher concentrations. Additionally, TSNPs significantly accelerated cell migration in the wound closure model as efficiently as TGFβ. Together, these findings offer promising TSNPs for biomedical applications and therapeutic agents due to their antioxidant properties, cytotoxicity protection, and wound closure acceleration. Full article

We report for the first time a method for forming polyacrylate nanoparticles using N-acryloylciprofloxacin as a sole monomer for emulsion polymerization. The procedure involves a free radical-induced emulsion polymerization of N-acryloylciprofloxacin monomer to produce a stable aqueous emulsion comprising uniformly sized polyacrylate nanoparticles. Dynamic light scattering analysis of the emulsions showed a single population of nanoparticles having an average diameter of 970 nm and average surface charge of −63 mV, indicative of the high stability of the emulsion and significantly enhance lipophilicity of the polymeric matrix of the nanoparticle. Antibacterial testing of the emulsions against the Gram-positive microbe Staphylococcus aureus and the Gram-negative Escherichia coli found in vitro activities identical to those of the reference clinical agent, ciprofloxacin. Assays against human colorectal carcinoma cells and human embryonic kidney cells showed essentially no cytotoxicity. This is the first study on the synthesis of aqueous nanoparticle emulsions assembled solely from a single monomer derived from the antibiotic agent. Full article

The increasing emphasis on environmental sustainability has placed biomass as a versatile and renewable resource, while the management and disposal of forest byproducts remain a significant challenge. This study explores the valorization of forest biomass residues derived from Pinus pinaster, Pinus pinea, and the invasive species Acacia dealbata, with a focus on their potential application as bioadsorbents. A comprehensive physicochemical characterization was conducted for different biomass fractions (leaves, needles, and branches of varying diameters). Leaves and needles contained higher amounts of extractives (from 7.7% in acacia leaves to 18.8% in maritime pine needles) and ash (3.4 and 4.2% in acacia leaves and stone pine needles, respectively), whereas branches contained more holocellulose (from 59.6% in P. pinea small branches to 79.2% in P. pinaster large branches). ATR-FTIR and pHpzc analyses indicated compositional and surface charge differences, with higher pHpzc values in A. dealbata relative to Pinus. TG analysis showed that acacia large branches degraded at a lower temperature (320 °C) compared to Pinus species (440–450 °C). Overall, the findings highlight the suitability of these underutilized forest byproducts as bioadsorbents, contributing to the advancement of circular economy practices. Full article

The rational design of multifunctional electrocatalysts requires synergistic integration of conductive scaffolds with redox-active components. Here, a hierarchical core–shell NiCo₂S₄ grown/anchored on Co₉S₈-loaded carbon nanofibers (NCS/CS/CNFs) was synthesized via an electrospinning and hydrothermal approach and systematically characterized. FESEM/TEM confirmed a core-shell nanofiber structure with a NiCo₂S₄ shell thickness of ~30–70 nm, increasing the fiber diameter to ~290 ± 30 nm, while BET analysis revealed a surface area of 24.84 m² g⁻¹ and pore volume of 0.042 cm³ g⁻¹, surpassing CS/CNFs (6.12 m² g⁻¹) and NCS (4.85 m² g⁻¹). XRD confirmed crystalline NiCo₂S₄ and Co₉S₈ phases, while XPS identified mixed Ni²⁺/Ni³⁺ and Co²⁺/Co³⁺ states with strong Ni-S/Co-S bonding, indicating enhanced electron delocalization. Electrochemical measurements in 1 M KOH demonstrated outstanding OER activity, with NCS/CS/CNFs requiring only 324 mV overpotential at 10 mA cm⁻², a Tafel slope of 125.7 mV dec⁻¹, and low charge-transfer resistance (0.33 Ω cm²). They also achieved a high areal capacitance of 1412.5 μF cm⁻² and maintained a stable current density for >5 h. For methanol oxidation, the composite delivered 150 mA cm⁻² at 0.1 M methanol, ~1.6 times that of CS and 1.3 times that of NCS, while maintaining stability for 18,000 s. This bifunctional activity underscores the synergy between conductive CNFs and hierarchical sulfides, offering a scalable route to durable electrocatalysts for water splitting and direct methanol fuel cells. Full article

Background: Glioblastoma multiforme (GBM) is an aggressive primary brain malignancy associated with poor prognosis and limited therapeutic options. Nanoparticle-based drug delivery systems provide a promising strategy to enhance treatment efficacy by circumventing barriers such as the blood–brain barrier. This study was conducted to synthesize, characterize, and evaluate the in vitro anticancer potential of andrographolide–iron oxide nanoparticles (AG-IONPs) against GBM cells. Methods: Iron oxide nanoparticles (IONPs) were synthesized through co-precipitation and subsequently functionalized with andrographolide. Morphology, size, and surface charge were assessed by transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential analysis. Functionalization was confirmed by Fourier-transform infrared spectroscopy (FTIR) and UV–Vis spectroscopy. Nanoparticle stability was monitored over three months. Cytotoxicity toward DBTRG-05MG cells was evaluated using MTT assays at 24, 48, and 72 h, while anti-migratory effects were determined using scratch-wound assays. Results: TEM analysis revealed nearly spherical IONPs (7.0 ± 0.15 nm) and AG-IONPs (13.5 ± 1.25 nm). DLS indicated an increased hydrodynamic diameter following functionalization, while zeta potential values decreased from +21.22 ± 1.58 mV to +8.68 ± 0.87 mV. The successful incorporation of andrographolide was confirmed by FTIR and UV–Vis spectra. AG-IONPs demonstrated excellent colloidal stability for up to three months. Cytotoxicity assays revealed a dose- and time-dependent decrease in cell viability, with LC₅₀ values declining from 44.01 ± 3.23 μM (24 h) to 15.82 ± 2.30 μM (72 h). Scratch-wound assays further showed significant inhibition of cell migration relative to untreated controls. Conclusions: AG-IONPs exhibit favorable physicochemical properties, long-term stability, and potent anti-proliferative and anti-migratory effects against GBM cells in vitro. These findings support their potential as a multifunctional therapeutic platform, warranting further preclinical investigation. Full article

Eight different types of tea bags were investigated in this work using dynamic light scattering, electrophoretic mobility and nanoparticle tracking analysis methods to determine the concentration and size of released particles from the bag materials at different temperatures and times. Infrared spectroscopy and calorimetric methods confirmed that the bag material consisted of synthetic (nylon or polypropylene) or natural polymers (cellulose). The size of the released particles lies in the range of 200 nm^–1 µm with an initial bimodal distribution and with an average diameter of about 600 nm. The concentration of released particles increases with increasing temperature and brewing time. The released particles of synthetic polymers remain quite stable and are not affected by natural enzymes, while cellulose particles are easily degraded by the proteolytic complex Morikrase. When analyzing the electrophoretic mobility, it was found that the released particles have a negative surface charge, which probably determines the absence of cytotoxicity established on the epithelial cell line Caco-2 even at the maximum values of the observed particle concentrations (14 × 10⁹ particle/L for synthetic polymers and 170 × 10⁹ particle/L for cellulose). Full article

Well cementing is an important step in oil and gas development. It uses cement to seal the formation and the casing, preventing fluid leakage. However, when conducting offshore oil well cementing operations, deep-water formations are usually weakly consolidated soils, and it is difficult to form a good cementation between the cement and formation. Therefore, enhancing the strength of the formation is one of the effective measures. This study uses the microbial-induced carbonate precipitation technology to cement sandy formations containing clay minerals. The triaxial tests were conducted to evaluate the consolidation effectiveness in the presence of three clay minerals: montmorillonite, illite, and kaolinite. X-ray computed tomography was utilized to characterize microscopic pore parameters, while thermogravimetric analysis, X-ray diffraction, and surface potential measurements were applied to analyze the mechanisms of clay minerals affecting microbial consolidation. The results showed that microbial mineralization mainly affects the cohesion of the samples. The cohesion of the montmorillonite sample increased from 20 kPa to 65.4 kPa, an increase of up to 3.27 times. The other two samples (illite and kaolinite) had increases of only 0.33 times and 1.82 times. Although the strength of the montmorillonite sample increased the most, unexpected large pores appeared with a diameter of over 120 µm, accounting for 7.1%. This is mainly attributed to the mineral expansion property. The expansion of the minerals will trap more microorganisms in the sample, thereby generating more calcium carbonate. And it also reduced the gaps between sand particles, creating favorable conditions for the connection of calcium carbonate. Although the surface charge of the minerals also affects the attachment of microorganisms, all three minerals have negative charges and a difference of no more than 0.84 mV (pH = 9). Therefore, the expansion property of the minerals is the dominant factor affecting the mechanical and microstructure of the sample. Full article