Search Results (152)

Photodynamic therapy (PDT) is a reactive oxygen species (ROS)-based treatment modality whose efficacy is often limited by poor photosensitizer stability and delivery. In this study, mesoporous silica-coated iron oxide nanoclusters (MNCs) were synthesized and loaded with protoporphyrin IX (PPIX) to obtain a multifunctional PPIX@MNC nanoplatform. Physicochemical characterization was performed using transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential analysis, and Fourier-transform infrared spectroscopy (FTIR). The biological effects of MNC, free PPIX, and PPIX@MNC were evaluated in HaCaT cells—as a general epithelial model—under dark conditions, light irradiation, cold atmospheric plasma (CAP) exposure, and combined CAP-assisted photodynamic treatment. FTIR, DLS, and zeta potential analyses confirmed successful incorporation of PPIX into the nanoclusters. Cell viability assays revealed pronounced phototoxicity of free PPIX, with the IC50 value decreasing from 44.4 ± 3.5 nM under dark conditions to 14 ± 2 nM following light activation, corresponding to a phototoxicity index of 3.17. CAP further enhanced PPIX-mediated cytotoxicity, and the CAP-assisted photodynamic group exhibited the strongest response, with an IC50 value of 9.6 ± 1.1 nM. CAP further enhanced PPIX-mediated cytotoxicity. Increased ROS generation, enhanced apoptosis, and marked mitochondrial membrane potential disruption were observed particularly in CAP-Light-PPIX-treated cells. Although encapsulation of PPIX within MNCs reduced acute cytotoxicity compared with free PPIX, the nanoplatform retained responsiveness to light and CAP stimulation. These findings demonstrate that CAP potentiates PPIX-mediated photodynamic effects through enhanced oxidative stress and suggest that mesoporous silica-coated magnetic nanoclusters represent a promising platform for controlled photosensitizer delivery in CAP-assisted PDT applications. Full article

This review examines the state-of-the-art in catalytic oxidative dehydrogenation of propane and butane to olefins under oxygen-free gas-phase conditions (FOx–PCODH and FOx–BCODH). First, it is compared with traditional methods for C₃–C₄ olefin production, using reaction enthalpies as an indicator of the process energy required. The role of catalyst oxygen species, including lattice and chemisorbed oxygen, is discussed in relation to olefin formation under oxygen-free gas-phase operation. This is followed by a review of V₂O₅-based catalysts, with particular emphasis on co-catalysts and catalyst supports. The performance of V₂O₅-based catalysts for FOx–PCODH is assessed using overall olefin formation rates. Special attention is given to catalyst performance in the mini-fluidized CREC Riser Simulator, which exhibit the highest overall olefin formation rates. These studies are also valuable to shed light into the FOx–PCODH reaction mechanism and to determine paraffin conversion, olefin selectivity, oxygen availability, and coke formation. This data can be used to determine FOx–PCODH kinetic parameters by assessing the effects of temperature, contact time, paraffin partial pressure, and catalyst-to-feedstock ratio. Finally, this review analyzes Barracuda-based numerical simulations of a large-scale downer reactor using statistically derived kinetic parameters. These simulations are employed to confirm the viability of the FOx–PCODH process at an industrial scale. Full article

Tungsten trioxide (WO₃) is the most widely studied cathodic electrochromic (EC) material, serving as the core component of energy-efficient smart windows, displays, and optical modulation devices. Post-deposition annealing, as a critical post-processing technique, precisely regulates the microstructure, crystallinity, oxygen vacancy concentration, and electronic structure of WO₃ thin films, thereby directly determining their EC performance. This review summarizes the research progress of annealing effects on WO₃ films, focusing on the synergistic regulation of annealing temperature, atmosphere, and dwell time. It elaborates on the fundamental EC mechanisms of amorphous and crystalline WO₃, including polaron hopping and free-electron Drude behavior, and analyzes the influence of different deposition methods (magnetron sputtering, sol–gel, electrodeposition, etc.) on the annealing response of films. The optimal annealing windows for balancing optical modulation, coloration efficiency, switching speed, and cycling stability are clarified: moderate temperatures (200–350 °C) and inert/air atmospheres yield mixed amorphous–nanocrystalline structures with optimal oxygen vacancy content. Current challenges such as the inherent contrast–stability trade-off and thermal budget limitations of flexible substrates are discussed, and future directions including spatially resolved annealing, interface co-design, and machine learning-assisted optimization are prospected. This work provides a theoretical reference and process guidance for the development of high-performance WO₃-based EC devices. Full article

This study reports the synthesis of low-defect Prussian blue analogues (PBAs) using a single iron-source method and systematically investigates the influence of atmospheric components, particularly water and oxygen, on their oxidative decomposition. Our findings demonstrate that the oxidative degradation of PBAs is governed synergistically by moisture and oxygen, with ambient humidity identified as the primary factor determining both the extent and kinetics of their decomposition. Notably, a pure oxygen environment by itself does not trigger material degradation, while oxygen markedly accelerates the decomposition only in the presence of moisture. As a result of the oxidation, enhanced Coulombic interaction between sodium ions and cyano groups induces structural modifications in the lattice framework, driving a phase transformation from monoclinic to cubic symmetry, accompanied by changes in its unit cell volume. Furthermore, in high-humidity environments, atmospheric moisture promotes the gradual deintercalation of sodium ions from the Prussian blue framework, resulting in the conversion of sodium-rich Prussian blue to the sodium-deficient form. Concurrently, an increase in lattice defect density leads to partial structural collapse, inducing the release of free ferrocyanide ions, which may subsequently react with the deintercalated sodium ions to form the sodium ferrocyanide impurity phase. We also find that the preferential decomposition of low-spin iron over high-spin iron within the framework leads to a further reduction in its electrochemical capacity. In contrast, potassium Prussian blue exhibits minimal interaction with water molecules and can effectively repel them through steric hindrance. Therefore, partial substitution of sodium with potassium ions is proposed as a viable strategy to enhance the structural stability of the Prussian blue framework, improve the storage performance of sodium Prussian blue (NaPB), and mitigate water ingress. This work offers fundamental insights into the storage characteristics and oxidative degradation mechanisms of PBAs. Full article

Aromatic compounds are abundant in urban and industrial environments and potentially serve as one of the primary precursors for new particle formation (NPF). Pi-pi stacking is a distinctive weak interaction observed between aromatic compounds. Aromatic oxygenated organic molecules (AOOM) are key products of atmospheric oxidation of aromatic compounds; however, the role of pi-pi stacking in their involvement in atmospheric new particle formation (NPF) remains unclear. This study used quantum chemical calculations to reveal the nucleation mechanism of AOOM through pi-pi stacking and hydrogen bonding. The results indicate that the contribution of pi-pi stacking to nucleation in aromatic compounds is primarily determined by the stacking area. For aromatic hydrocarbons with 1–2 phenyl groups, the Gibbs free energy (ΔG) of dimolecular clusters formed solely by pi-pi stacking is positive. In contrast, for polycyclic aromatic hydrocarbons with three or more phenyl groups, the ΔG of these clusters decreases significantly and becomes negative. Single-phenyl AOOM primarily participates in the NPF process through hydrogen bonding with sulfuric acid molecules. In this work, an explanation is provided for observations and laboratory findings of the appearance of aromatic-ring-retaining species in nanoparticles. The discovery of pi-pi stacking also completes the variety of atmospheric nucleation weak interactions. The oxidation and nucleation mechanisms of aromatic compounds should be reassessed, considering the effects of pi-pi stacking, especially polycyclic aromatic hydrocarbons. These findings have important implications for sustainable urban air-quality management. By clarifying the role of pi-pi stacking, particularly in polycyclic aromatic hydrocarbons, this study may improve predictions of new particle formation, refine secondary organic aerosol modeling, and inform targeted emission-control policies to protect public health and mitigate climate impacts. Full article

This work investigated the effect of yttrium addition on the pre-oxidation behavior of Fe–25Ni–20Cr–4Al–1Nb–1Mn–1.5Si-based alloys at 1000 °C in a 4% H₂ + 0.2% CH₄ + Ar + 0.25% H₂O atmosphere. The oxidation resistance and oxide scale adhesion were evaluated through cyclic oxidation tests and micro-scratch measurements. Results show that the Y-free alloy formed a discontinuous oxide layer, whereas all Y-containing alloys formed a continuous and dense Al₂O₃ scale. Incorporating 0.2 wt.% Y increased the work of adhesion by approximately 7 to 9 times relative to the Y-free sample, indicating a pronounced interfacial strengthening effect. The role of yttrium content and oxygen partial pressure in promoting alumina-scale formation was discussed based on thermodynamic considerations and microstructural evidence. Full article

This paper presents a theoretical engineering feasibility analysis of the RK-X photocatalytic process for In Situ Resource Utilisation (ISRU) on Mars. Experimental validation under simulated Martian conditions is the essential next step before any mission deployment claim can be made. The RK-X process converts the two most abundant Martian resources, atmospheric carbon dioxide (CO₂) and subsurface water ice (H₂O), into formic acid (HCOOH) and oxygen (O₂) through a fulvic acid-based photocatalytic cycle validated at the industrial scale in Hungary. A reference module processing 10 tonnes of CO₂ per Earth year yields 10.459 tonnes of formic acid and 3.636 tonnes of oxygen, sufficient to sustain a six-person crew for approximately two Earth years with a 198% safety margin over nominal respiratory demand. The economic analysis indicates that importing equivalent oxygen from Earth costs $1.82–$3.64 million per year; equivalent energy storage (Li-ion) costs $30.5–$61 million for one-time use. Formic acid stores 15.25 MWh of energy in ambient-stable liquid form at a round-trip efficiency of 68.64% without cryogenic infrastructure. A photovoltaic array of 55.37 m² provides the primary energy source; a kilowatt-class nuclear fission reactor constitutes the strategic opportunity for continuous, dust-storm-immune operation with free thermal co-generation. Three critical research gaps have been identified requiring laboratory validation before Mars deployment: (i) catalyst performance at the Martian CO₂ partial pressure (p(CO₂) < 10 mbar, T = 15 °C); (ii) water ice and dry ice extraction at an operational scale; and (iii) integrated closed-loop system demonstration. Built on Earth-proven chemistry with identified, addressable development pathways, the RK-X process theoretically resolves the problems of oxygen supply, seasonal energy storage, water management, and cryogenic infrastructure within a single closed-loop chemical cycle. Full article

The scalable and sustainable production of graphene remains a significant challenge due to the high cost, complex processing, and environmental impact associated with fossil-derived graphite precursors. In this work, we report a biorenewable pathway for producing graphitic carbon from industrial hemp biomass, yielding a plant-derived material called CleanGraphene. This approach provides a renewable and potentially scalable alternative to petroleum- and coal-based graphene production while maintaining competitive structural and electrical performance. CleanGraphene samples are systematically characterized using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) to evaluate crystallographic order, layer stacking, defect density, surface chemistry, and thermal stability. The results show that optimized CleanGraphene materials consist of multilayer graphene-like platelets with compact interlayer spacing (d(002) ≈ 3.36–3.37 Å), extended crystallite coherence lengths (L_c up to ~75 nm), large in-plane sp² domains (L_a exceeding ~200 nm), and relatively low defect densities, indicating well-developed graphitic ordering. Electrical conductivity measurements using a binder-free pelletization method and four-point probe analysis demonstrate that the highest quality CleanGraphene samples achieve conductivities of (8.4–8.6) × 10⁴ S m⁻¹, surpassing leading commercial graphene benchmarks measured under identical conditions. Structure–property correlations confirm that electrical performance is governed primarily by crystallite coherence, defect density, and interlayer stacking order, while surface oxygen content plays a secondary role within an ordered graphitic framework. All CleanGraphene samples exhibit excellent thermal stability, retaining more than 95% mass up to ~800–900 °C under an inert atmosphere. Collectively, these findings establish quantitative quality benchmarks for hemp-derived graphene and demonstrate that biomass-based graphene can achieve electrical and thermal performance comparable to, and in some cases exceeding, conventional commercial products. This work highlights industrial hemp as a promising renewable precursor for the scalable production of high-performance graphitic nanomaterials for electrically and thermally conductive composite applications. Full article

Reactive oxygen species (ROS) are a class of molecules or free radicals with strong oxidizing properties. They have attracted increasing attention in soil research in recent years because of their perceived importance in many soil biochemical processes. Previous reviews of ROS in soil mainly focused on their impacts on carbon emissions and organic pollutant remediation, with few descriptions of the mechanisms responsible for ROS generation, and a comprehensive understanding of their environmental effects is still lacking. Therefore, the present review provides details on the sources and underlying generation mechanisms of ROS in soil. These mechanisms include inputs via atmospheric deposition, metal–mineral reactions, root exudation, microbial metabolism, enzymatic reactions and various organic matter transformations. In contrast to previous reviews, we also discuss mutual conversion between different types of ROS in soil. The impacts of ROS on the soil environment are further explored, such as element cycling, pollutant degradation, and the growth and reproduction of plants and microorganisms, in order to provide a systematic understanding of the various processes involving ROS in soil, thereby guiding better soil management decisions. Finally, we highlight future research trends, suggesting that the advancement of in situ detection methods is crucial for establishing the precise contribution of abiotic ROS processes to global soil carbon and nutrient models. Full article

The increasing demand for high-purity lead sulfide (PbS) for optoelectronic applications necessitates efficient methods to remove residual antimony sulfide (Sb₂S₃) from complex ores—a challenge due to their chemical similarity and fine intergrowth. This study presents a hybrid purification strategy combining vacuum distillation pretreatment with oxygen-free alkaline selective leaching. Thermodynamic analysis using Eh-pH diagrams revealed significant differences in the behavior of trace Sb₂S₃ and bulk PbS under alkaline conditions (pH 9–11), identifying a suitable window for selective dissolution. The process begins with mechanical ball milling to break Sb₂S₃ inclusions and improve reaction kinetics, followed by anaerobic leaching in a sealed reactor under inert atmosphere using a NaOH solution at a controlled potential (Eh 0.1–0.35 V vs. SHE). Multiple characterization techniques confirmed that Sb₂S₃ undergoes dissolution and conversion while the PbS phase remains intact. Notably, zeta potential measurements (−12.3 mV) and high conductivity (204 mS/cm) indicated the formation of a stable colloidal dispersion system favorable for interfacial reactions. Under optimal conditions, antimony removal exceeded 99% with lead loss below 1%. Overall, the proposed strategy offers a technically viable route to produce ≥99.9% pure PbS from polymetallic sources, addressing a longstanding separation challenge. Full article

Carbon-based bifunctional oxygen electrocatalysts with rationally designed architectures are essential for high-performance rechargeable zinc–air batteries (ZABs), yet the concurrent optimization of catalytic activity, durability, and mass transport remains challenging. Herein, hierarchical ZnCo carbon nanofibers/carbon nanotubes (CNFs@CNTs) are fabricated via single-nozzle electrospinning followed by melamine-assisted pyrolysis under a ZnCl₂-regulated atmosphere. During thermal treatment, Co species embedded within carbon nanofibers catalyze in situ carbon nanotube growth, while ZnCl₂ vapor modulates the carbonization process and surface chemistry, collectively generating a hierarchical CNFs@CNTs architecture with high surface area and abundant exposed active sites. As a result, ZnCo CNFs@CNTs exhibit outstanding bifunctional ORR/OER activity, surpassing Zn-free and Co-free counterparts. Combined structural and electrochemical analyses reveal that the synergistic interaction between Co active centers and Zn-assisted carbon structural regulation enhances reaction kinetics and long-term stability. When implemented as air electrodes in rechargeable ZABs, ZnCo CNFs@CNTs deliver high power density, reduced charge–discharge polarization, and excellent cycling durability, demonstrating strong practical applicability. This work presents an effective strategy for constructing hierarchical CNFs@CNTs composites via electrospinning and dual-component thermal regulation, offering new insights into the design of high-efficiency bifunctional air electrodes for advanced ZABs. Full article

Calcium carbonate is a widely used filler in polymer composites due to its low cost and ability to improve stiffness, dimensional stability, and impact resistance. However, its hydrophilic surface limits compatibility with nonpolar polymer matrices, making surface modification essential to improve filler dispersion and interfacial adhesion. Stearic acid is commonly applied as a surface modifier for calcium carbonate because it readily chemisorbs onto the mineral surface and forms densely packed self-assembled monolayers that improve hydrophobic character. Despite its widespread use, stearic acid exhibits limited thermal and interfacial stability under polymer processing conditions, motivating the development of stabilization strategies. In this work, gamma and electron-beam irradiation were applied to stearic-acid-modified calcium carbonate to modify the surface-bound stearic acid layer with the aim of enhancing its interfacial stability, surface resistance, and hydrophobic performance, and to evaluate the influence of irradiation atmosphere on these effects. The modified materials were characterized in terms of structural integrity, surface wettability, surface free energy, thermal stability, and optical properties. The results demonstrate that ionizing radiation enhances surface hydrophobicity and coating durability while preserving the crystal structure of the CaCO₃ substrate. Gamma irradiation of stearic-acid-modified vaterite exhibited strong atmosphere dependence, with improved hydrophobicity under oxygen-free conditions, whereas electron-beam irradiation showed more robust and oxygen-insensitive behavior. Based on the observed improvements in hydrophobicity, surface free energy, and thermal stability, electron-beam irradiation emerges as a promising and less atmosphere-sensitive approach for producing durable stearic-acid-modified CaCO₃ fillers suitable for polymer composite applications. Full article

(Na_0.5Bi_0.5)TiO₃-BaTiO₃-SrTiO₃-based lead-free piezoelectric ceramics are one of the possible replacements for Pb(Zr_1−xTi_x)O₃. Although they are considered a promising alternative actuator material due to their large electric-field-induced strains, they have several drawbacks, such as large strain hysteresis and the requirement of a high electric field to obtain large electric-field-induced strains. Sintering parameters strongly influence the electrical properties. Thus, the effect of sintering parameters, including atmosphere (air/oxygen), temperature (1150 °C~1250 °C) and holding time (1~20 h) on the sintering behavior of 0.685(Na_0.5Bi_0.5)TiO₃-0.065BaTiO₃-0.25SrTiO₃ electroceramics was studied. Then, the influence of sintering atmosphere on the piezoelectric, ferroelectric and dielectric properties of 0.685(Na_0.5Bi_0.5)TiO₃-0.065BaTiO₃-0.25SrTiO₃ electroceramics sintered at 1250 °C for 1 h was investigated. Sintering in oxygen improves density and restrains grain growth including abnormal grain growth. 0.685(Na_0.5Bi_0.5)TiO₃-0.065BaTiO₃-0.25SrTiO₃ electroceramics sintered in oxygen exhibit smaller grain size, higher density, similar inverse piezoelectric coefficient d₃₃* and lower strain hysteresis compared to air-sintered samples. The effect of sintering atmosphere on grain growth is explained using the mixed control mechanism of boundary migration. Full article

Mixed-anion silicate–phosphate oxysulfide glasses have attracted increasing interest due to their tunable thermal stability, electrical response, and potential use in functional glass and glass–ceramic materials. In this work, silicate–phosphate oxysulfide glasses in the SiO₂-P₂O₅-K₂O-MgO-SO₃-ZnO system were examined to determine how partial substitution of MgO with ZnO influenced their thermal and electrical properties under reducing conditions. Melting in a strongly reducing atmosphere predominantly converted sulfur to reduced sulfur species, producing mixed oxygen–sulfur glass networks. Differential scanning calorimetry (DSC) shows that ZnO substitution reduces the configurational heat capacity at the glass transition (ΔC_p) by up to ~40%, suppresses crystallization exotherms, and shifts crystallization onset temperatures by more than 100 °C toward higher values, indicating enhanced network rigidity. Potassium and magnesium K-edge X-ray absorption spectroscopy (XAS) revealed increased short-range ordering around Mg²⁺ in Zn-free glasses after heat treatment, whereas Zn-containing glasses remain more structurally disordered. Impedance spectroscopy demonstrated that ZnO-substituted glasses exhibit higher activation energies for electrical transport (≈0.9–1.0 eV) and lower AC conductivity compared to Zn-free compositions, reflecting restricted alkali-ion mobility. These results demonstrate that partial substitution of MgO with ZnO significantly enhances the thermal stability and electrical insulating behavior of reduced silicate–phosphate oxysulfide glasses, providing valuable structure–property insights for the design of thermally stable functional glasses and glass–ceramics. Full article

Efficient oxidation of refractory sulfides, such as dibenzothiophene (DBT) and its derivatives, provides a promising strategy to produce fuel oils with ultra-low sulfur content, or even completely sulfur-free. In this study, a series of non-stoichiometric molybdenum oxides (MoO_x) were synthesized via a facile procedure and employed as efficient catalysts. These catalysts can effectively oxidize DBT and its derivatives into insoluble sulfones, which subsequently precipitate from the oil phase, achieving efficient sulfur removal. In this system, molecular oxygen from air can be activated by the MoO_x catalysts with oxygen vacancies into superoxide radicals, which act as active oxygen species to efficiently oxidize refractory sulfides. Under atmospheric pressure at 120 °C, complete sulfur removal (100%) was achieved for both DBT and its derivatives, representing significantly milder conditions compared to conventional hydrodesulfurization. The aerobic oxidation system could be reused for up to 12 consecutive cycles without any significant decline in sulfur removal. And complete desulfurization (100%) was regained after a simple washing of the separated solid phase. Then, a possible reaction procedure was subsequently proposed to describe the desulfurization route. The remarkable catalytic performance, together with the facile synthesis strategy, indicates the potential of this approach for constructing other transition metal oxides used in various advanced aerobic oxidation reactions. Full article