Search Results (12,047)

Hydrogen, as an alternative energy carrier, presents significant prospects for the transition to more environmentally friendly energy solutions. However, its efficient and safe storage remains a challenge, as materials with high adsorbent capacity and long-term storage capability are required. This study focuses on the synthesis and characterization of a composite material comprising carbon fiber and manganese dioxide (MnO₂/CFs), for the purpose of hydrogen storage. Carbon fiber was chosen as the basis for the composition of the composite material due to its large active surface area and its excellent mechanical, thermal, and electrochemical properties. The deposition of MnO₂ on the surface of carbon fibers took place through two different synthetic pathways: electrochemical deposition and chemical synthesis under different conditions. The electrochemical method enabled the production of a greater amount of oxide with optimized structural and chemical properties, whereas the chemical method was simpler but required more time to achieve comparable or lower-capacity performance. Elemental analysis of the electrochemically produced composites showcased an average of 40.5 ± 0.05 wt% Mn presence, which is an indicator of the quantity of MnO₂ on the surface responsible for hydrogen storage, while the chemically produced composites showcased an average of 7.6 ± 0.05 wt% Mn presence. Manganese oxide’s high specific capacity and reversible redox reaction participation make it suitable for hydrogen storage applications. The obtained results of the hydrogenated samples through physicochemical characterization indicated the formation of the MnOOH intermediate. Regarding these findings it may be remarked that carbon fiber/MnO₂ composites are promising candidates for hydrogen storage technologies. Finally, the fabricated carbon fiber/MnO₂ composites were applied successfully as working electrodes for analysis of the [Fe(CN)₆]^3−/4− redox system in aqueous KCl solutions. Full article

Root exudates are key mediators of plant–soil–microbe interactions, shaping rhizosphere dynamics and influencing agroecosystem resilience. Comprising diverse primary and secondary metabolites, these compounds are actively secreted through specific transport pathways and are modulated by intrinsic plant traits and environmental conditions. Root exudates serve as chemical signals that recruit and structure microbial communities, facilitating nutrient mobilization, microbial feedbacks, and the regulation of plant growth and stress responses. By modulating soil chemical, physical, and biological properties, exudates contribute to carbon cycling, soil health, and the maintenance of ecosystem services. Moreover, they play multifunctional roles in enhancing plant tolerance to abiotic and biotic stresses, while also mediating interactions with neighboring plants. This review provides a holistic perspective on root exudation, encompassing their mechanisms and drivers, roles in rhizosphere ecology and plant stress adaptation, and methodological advances, while highlighting opportunities to harness these processes for resilient, productive, and sustainable agroecosystems. Full article

Nanoporous gold (np-Au) has attracted significant attention for biomedical and electrochemical applications due to its high surface area, tunable morphology, and excellent biocompatibility. In this study, polycrystalline gold surfaces were modified by anodization in 0.3–0.9 M oxalic acid to produce np-Au layers. The influence of anodization conditions on surface morphology, chemical composition, electronic properties, and corrosion resistance in artificial saliva was systematically investigated. Surface morphology and porosity were analyzed by scanning electron microscopy combined with image analysis, revealing a transition from fine and uniform porosity to highly developed but structurally heterogeneous nanoporous structures with increasing oxalic acid concentration. Energy-dispersive spectroscopy confirmed surface oxidation and adsorption of oxygen- and carbon-containing species after anodization, while gold remained the dominant component. Scanning Kelvin probe measurements demonstrated significant modifications of surface electronic properties, including changes in contact potential difference, governed by nanostructure geometry and surface chemistry. Electrochemical tests in artificial saliva showed that increasing nanoporousness led to reduced thermodynamic stability, with the sample anodized in 0.3 M oxalic acid providing the most favorable balance between corrosion resistance and surface activity. These results demonstrate that oxalic acid anodization is a simple and effective approach for tailoring gold surfaces for biomedical applications, particularly in dentistry. Full article

Floods and wildfires are two extreme environmental events with significant yet different impacts on soil health and on two particularly important soil pollutants, heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs), which are directly associated with ishytoxic properties and their ability to enter the food chain. The present study includes a methodological approach that was based on a literature review of published studies conducted worldwide regarding these two phenomena. The main forms of both pollutants, their possible sources and inevitable deposition onto the soil surface, along with their behavior–transport–mobility, and their residence time in soil were investigated. Furthermore, the changes that both HMs and PAHs induce in the physicochemical properties of post-flood and post-fire soils (in soil pH, Cation Exchange Capacity (CEC), organic matter content, porosity, mineralogical alterations, etc.), are investigated after a literature review of various case studies. Wildfires, in contrast to floods, can more easily remove large quantities of heavy metals into the soil ecosystem, most likely due to the intense erosion they cause. At the same time, floods appear to significantly burden soils with PAHs. In wildfires, the largest mean increases were observed for Mn (386%), Zn (300%), and Cu (202%). In floods, Pb showed the highest mean increase (534%), with Cd also rising substantially (236%). Regarding total PAHs, mean post-event concentrations reached 482.3 μg/kg after wildfires, compared to 4384 μg/kg after floods. Changes in the structure and chemical composition of flooded and burned soils may also affect the mobility and bioavailability of the pollutants under study. Overall, these two phenomena significantly alter soil quality, affecting both ecological processes and potential health impacts. Full article

Microbial biosurfactants (mBSs) are bioactive molecules with diverse applications, notably as antimicrobial agents against antibiotic-resistant pathogens. Produced by bacteria and yeasts, mBSs are classified as glycolipids, lipopeptides, polymeric, and particulate types. The global rise in multidrug-resistant organisms, such as Escherichia coli, Klebsiella pneumoniae, Salmonella typhimurium, Pseudomonas aeruginosa, and Acinetobacter baumannii, underscores the urgent need for new antimicrobial strategies. mBSs disrupt microbial growth by interacting with the lipid components of pathogens, offering promising alternatives to conventional antibiotics. This review highlights the sources, chemical structures, and properties of mBSs, their antimicrobial activities, synergistic effects with antibiotics, and structure–activity relationships. Special emphasis is placed on surfactant modification, where targeted changes—such as valine substitution in surfactin—significantly lower critical micelle concentrations (CMC) and enhance antimicrobial potency. Such rational engineering demonstrates how biosurfactants can be tailored for improved biomedical performance while minimizing cytotoxicity. In parallel, artificial intelligence (AI) algorithms, including artificial neural networks and genetic algorithms, optimize yields, predict substrate suitability from agricultural residues, and guide microbial strain engineering. AI models can predict interfacial behavior and synchronize fermentation with purification. Advancing the understanding of mBS interactions with microbial membranes, combined with modification strategies and AI-guided optimization, is essential for developing targeted therapies against resistant infections. Future research should integrate these approaches to engineer novel derivatives, reduce costs, and validate clinical potential through comprehensive in vivo studies. Full article

Starch systems and their extrudates can be used as edible films, carriers, and encapsulants for bioactive substances in various industries, primarily the food, medicine, and pharmacy industries. Using appropriate modification methods, it is possible to alter their physicochemical properties to improve specific functional parameters, thereby enhancing their application potential. The aim of this study was to characterize potato starch extrudates enriched with two types of edible oils (rapeseed or sunflower) at concentrations of 3%, 6%, and 9%. Chemical modification was carried out using K₂CO₃ as a catalyst. The structure of native and modified starch extrudates was examined using optical/confocal microscopy, FTIR, and LTNA (low-temperature nitrogen adsorption). Analogous starch dispersions were studied using static and dynamic light scattering, SLS/DLS, nephelometric methods, and electrophoretic mobility measurements to determine surface charge levels and stability. Additionally, viscosity curves were determined as a function of time and temperature. It was found that starch extrudates with 6% sunflower oil content showed optimal functional properties, characterized by greater stability, higher structural order, and better oil complexation. These findings directly translate into significant potential applications, including the development of functional products in the food industry. Full article

Transient receptor potential canonical (TRPC) channels function as multimodal cation channels that integrate chemical and mechanical cues to regulate cellular signaling. Among them, TRPC3 and TRPC6 have been studied primarily in the context of cardiovascular and renal physiology, and their roles in other organ systems are now increasingly recognized. Although these channels are known to be activated downstream of phospholipase C (PLC) signaling, especially 1,2-diacylglycerol (DAG) production, their precise modes of activation under native physiological conditions remain incompletely understood. Recent structural and functional studies have greatly advanced our understanding of their primary activation by DAG. This review summarizes how decades of physiological analyses have revealed multiple modes of TRPC3 and TRPC6 channel activation beyond DAG gating, providing a broader perspective on their diverse regulatory mechanisms. This review also highlights recent progress in elucidating the channel properties, activation mechanisms, and the physiological as well as pathophysiological roles of TRPC3 and TRPC6 in cardiovascular contractility and remodeling, and discusses the remaining challenges that will lead to the establishment of TRPC3 and TRPC6 as validated therapeutic targets. Full article

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. Full article

Modulating the electronic structure and surface properties of graphitic carbon nitride (g-C₃N₄) by chemically phosphorus doping is an effective strategy for improving its photocatalytic performance. However, in order to benefit from practical applications, the cost-effectiveness, efficiency, and optimization of the doping level need to be investigated further. Herein, we report a structural doping of P into g-C₃N₄ by in situ polymerization of the mixture of dicyandiamide (DCDA) and phosphorus pentoxide (P₂O₅). As an alternative to previous studies that used complex organic phosphorus precursors or post-treatment strategies, this work proposed a one-pot thermal polycondensation method that is low-cost, scalable, and enables controlled phosphorus substitutions at carbon sites of the g-C₃N₄ heptazine structure. Most of the structural features of g-C₃N₄ were well retained after doping, but the electronic structures and light harvesting capacity had been effectively altered, which provided not only a much better charge separation but also an improvement in photocatalytic activity toward H₂ evolution under irradiation of a simulated sunlight. The optimized sample with P-doping content of 9.35 at.% (0.5PGCN) exhibited an excellent photocatalytic performance toward H₂ evolution, which is over 5 times higher than that of bulk g-C₃N₄. This work demonstrates a facile one-step in situ route for producing high-yield photocatalysts using low-cost commercial precursors, offering practical starting materials for studies in solar cells, polymer batteries, and photocatalytic applications. Full article

Graphene (GRA) and graphene oxide (GO) have drawn significant attention in materials science, chemistry, and nanotechnology because of their tunable physicochemical properties and wide range of potential uses in biomedical and environmental applications. Building reliable, large-scale molecular models of GRA and GO is essential for molecular simulations of wetting, adsorption, and catalytic behavior. However, current methods often struggle to generate large, chemically consistent sheets at high oxidation levels. In addition, the resulting structures are frequently incompatible across different simulation packages. This work introduces a step-by-step protocol with custom Tool Command Language (Tcl) and modified Python version 3.12 scripts for building large-scale, AMBER-compatible GO structures with oxidation levels from 0% to 68%. The workflow applies a systematic surface modification strategy combined with post-processing and atom-type assignment routines to ensure chemical accuracy and force field consistency. The dataset includes fifteen MOL2 format files of 20 × 20 nm² GO sheets, ranging from pristine to highly oxidized surfaces, each validated through oxidation-ratio analysis and structural integrity checks. Together, the dataset and protocol provide a design of scalable and chemically reliable GO molecular models for molecular dynamics simulations. Full article

Chitosan (CS) and carboxymethyl chitosan (CMCS) are polysaccharides valued for their biocompatibility, reactivity, and film-forming capabilities. This study compares the surface characteristics and stability of CS and CMCS thin films crosslinked with citric acid (CTA), polyethylene glycol diglycidyl ether (PEGDE), and glutaraldehyde (G). Flow behavior was assessed using steady-shear measurements, while film structure, morphology, and physical properties were analyzed by infrared spectroscopy, SEM, AFM, mechanical testing, and swelling experiments. Crosslinking generated new chemical bonds in both CS and CMCS films; however, interactions in CMCS did not result in stable cross-links and were comparatively weaker. These structural modifications influenced swelling behavior and enhanced stability, particularly in CS-based systems. Before neutralization, CS/PEGDE films exhibited the lowest swelling (67% ± 19) relative to unmodified CS (118% ± 25) and crosslinked samples such as CS/G2 (185% ± 30), CS/G1 (475% ± 88), and CS/CTA (520% ± 90). After neutralization, CS/G1 and CS/CTA maintained the highest swelling capacity. In contrast, CMCS films crosslinked with CTA and G1 dissolved rapidly in aqueous media due to high water uptake, while PEGDE- and G2-modified CMCS films demonstrated stability comparable to CS. Overall, the results highlight the superior stability and tunable surface properties of CS-based films, underscoring their potential for biomedical and packaging applications. Full article

Hexagonal boron nitride nanosheets (BNNSs) have emerged as one of the most promising materials for next-generation thermal management, driven by the intensifying heat dissipation demands of highly integrated electronics. While conventional polymer-based packaging materials are lightweight and electrically insulating, their intrinsically low thermal conductivity severely limits effectiveness in high-power devices. The remarkable thermal transport, wide bandgap, chemical robustness, and mechanical strength of BNNSs offer a compelling solution. This review provides a comprehensive overview of the structural and physical foundations that underpin the anisotropic yet exceptional thermal properties of bulk h-BN and BNNSs. We examine major synthesis routes including tape exfoliation, ball milling, liquid-phase exfoliation, chemical vapor deposition, and metal–organic chemical vapor deposition, highlighting how process mechanisms govern nanosheet thickness, defect density, crystallinity, and scalability. Particular emphasis is placed on the advantages of BNNSs in thermal management systems, from their use as high-efficiency thermally conductive fillers and advanced thermal interface materials. We conclude by examining key challenges including large-area growth, filler alignment, and interfacial engineering, and by presenting future research directions that could enable the practical deployment of BNNSs-based thermal management technologies. Full article

Transition metal (TM)-doped zinc oxide (ZnO) and zirconium dioxide (ZrO₂) nanocrystals exhibit complex correlations between crystal structure, defect chemistry, vibrational properties, and magnetic behavior that are strongly governed by synthesis route and dopant incorporation mechanisms. This review critically summarizes recent progress on Fe-, Mn-, and Co-doped ZnO and ZrO₂ nanocrystals synthesized by wet chemical, hydrothermal, and microwave-assisted hydrothermal methods, with emphasis on synthesis-driven phase evolution and apparent solubility limits. ZnO and ZrO₂ are treated as complementary host lattices: ZnO is a semiconducting, piezoelectric oxide with narrow solubility limits for most 3d dopants, while ZrO₂ is a dielectric, polymorphic oxide in which transition metal doping may stabilize tetragonal or cubic phases. Structural and microstructural studies using X-ray diffraction, electron microscopy, Raman spectroscopy, and Mössbauer spectroscopy demonstrate that at low dopant concentrations, TM ions may be partially incorporated into the host lattice, giving rise to diluted or defect-mediated magnetic behavior. When solubility limits are exceeded, nanoscopic secondary oxide phases emerge, leading to superparamagnetic, ferrimagnetic, or spin-glass-like responses. Magnetic measurements, including DC magnetization and AC susceptibility, reveal a continuous evolution from paramagnetism in lightly doped samples to dynamic magnetic states characteristic of nanoscale magnetic entities. Vibrational spectroscopy highlights phonon confinement, surface optical phonons, and disorder-activated modes that sensitively reflect nanocrystal size, lattice strain, and defect populations, and often correlate with magnetic dynamics. Rather than classifying these materials as diluted magnetic semiconductors, this review adopts a synthesis-driven and correlation-based framework that links dopant incorporation, local structural disorder, vibrational fingerprints, and magnetic response. By emphasizing multi-technique characterization strategies required to distinguish intrinsic from extrinsic magnetic contributions, this review provides practical guidelines for interpreting magnetism in TM-doped oxide nanocrystals and outlines implications for applications in photocatalysis, sensing, biomedicine, and electromagnetic interference (EMI) shielding. Full article

Stone cultural relics are primarily composed of sandstone, a water-sensitive rock that is highly susceptible to deterioration from environmental solutions and dry-wet cycles. Sandstone pagodas are often directly exposed to natural elements, posing significant risks to their preservation. Therefore, it is crucial to investigate the performance of sandstone towers in complex solution environments and understand the degradation mechanisms influenced by multiple environmental factors. This paper focuses on the twin towers of the Huachi Stone Statue in Qingyang City, Gansu Province, China, analyzing the changes in chemical composition, surface/microstructure, physical properties, and mechanical characteristics of sandstone under the combined effects of various solutions and dry-wet cycles. The results indicate that distilled water has the least effect on the mineral composition of sandstone, while a 5% Na₂SO₄ solution can induce the formation of gypsum (CaSO₄·2H₂O). An acidic solution, such as sulfuric acid, significantly dissolves calcite and diopside, leading to an increase in gypsum diffraction peaks. Additionally, an alkaline solution (sodium hydroxide) slightly hydrolyzes quartz and albite, promoting calcite precipitation. The composite solution demonstrates a synergistic ion effect when mixed with various single solutions. Microstructural examinations reveal that sandstone experiences only minor pulverization in distilled water. In contrast, the acidic solution causes micro-cracks and particle shedding, while the alkaline solution results in layered spalling of the sandstone surface. A salt solution leads to salt frost formation and pore crystallization, with the composite solution of sodium hydroxide and 5% Na₂SO₄ demonstrating the most severe deterioration. The sandstone is covered with salt frost and spalling, exhibiting honeycomb pores and interlaced crystal structures. From a physical and mechanical perspective, as dry-wet cycles increase, the water absorption and porosity of the sandstone initially decrease slightly before increasing, while the longitudinal wave velocity and uniaxial compressive strength continually decline. In summary, the composite solution of NaOH and 5% Na₂SO₄ results in the most significant deterioration of sandstone, whereas distilled water has the least impact. The combined effects of acidic/alkaline and salt solutions generally exacerbate sandstone damage more than individual solutions. This study offers insights into the regional deterioration characteristics of the Huachi Stone Statue Twin Towers and lays the groundwork for disease control and preventive preservation of sandstone cultural relics in similar climatic and geological contexts. Full article

Bone tissue engineering offers a promising alternative to autografts and allografts for treating critical bone defects. Hydrogels, three-dimensional hydrophilic polymer networks, have emerged as leading scaffold materials due to their ability to mimic native extracellular matrix properties while providing tunable biocompatibility, biodegradability, mechanical characteristics, and high water content, enabling nutrient transport and cell viability. These scaffolds can be loaded with bioactive cues, including growth factors, peptides, and nanoparticles, and can deliver stem cells, supporting localised and sustained bone regeneration. Recent advances in hydrogel design have improved osteoinductivity and osteoconductivity through controlled physical, chemical, and mechanical properties, and sophisticated fabrication strategies such as 3D bioprinting and nanostructuring. This review provides a comprehensive overview of hydrogel-based scaffolds for bone tissue engineering, discussing material types, bioactive factor delivery, host tissue interactions, including immune modulation and osteogenic differentiation, and the latest preclinical and clinical applications. Finally, we highlight the remaining challenges and critical design requirements for developing next-generation hydrogels that integrate structural integrity with biological functionality. Full article