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Ultra-high temperature ceramics (UHTCs), most notably transition metal carbides and borides, exhibit melting temperatures exceeding 3000 °C, making them appropriate candidates to withstand the extreme temperatures (∼2000 °C) expected to occur at the leading edges of hypersonic vehicles. However, their propensity to react rapidly with oxygen limits their sustained application. The high entropy paradigm enables the exploration of novel UHTC compositions that may improve on the oxidation resistance of conventional refractory mono-carbides and -diborides. The oxidation kinetics of candidate high entropy group IV + V (HfZrTiTaNb)C and (HfZrTiTaNb)B2 materials were evaluated at 1500–1800 °C using Joule heating in one atmosphere 0.1%–1% oxygen/argon gas mixtures for times up to 15 min. Possible mechanisms based on the resulting complex time, temperature, and oxygen partial pressure dependencies are discussed. The carbides formed porous and intergranular oxides. Oxidation resistance was improved upon a continuous external scale formation. The diborides formed dense external scales and exhibited better oxidation resistance compared to the carbides. This improvement was attributed to the formation of liquid boria. Both compositions showed an unexpected reduction in material consumption at 1800 °C for all times tested, compared to results at lower temperatures. An in-depth analysis of the composition and morphology of the oxide scale and sub-surface regions for specimens tested at 1800 °C revealed that the formation of denser group IV-rich (Hf, Zr, Ti) oxides mitigated the formation of the otherwise detrimental liquid-forming group V (Ta, Nb) oxides, leading to the improved oxidation resistance. [ABSTRACT FROM AUTHOR]

Ultra-high temperature ceramics (UHTCs), most notably transition metal carbides and borides, exhibit melting temperatures exceeding 3000 °C, making them appropriate candidates to withstand the extreme temperatures (∼2000 °C) expected to occur at the leading edges of hypersonic vehicles. However, their propensity to react rapidly with oxygen limits their sustained application. The high entropy paradigm enables the exploration of novel UHTC compositions that may improve on the oxidation resistance of conventional refractory mono-carbides and -diborides. The oxidation kinetics of candidate high entropy group IV + V (HfZrTiTaNb)C and (HfZrTiTaNb)B2 materials were evaluated at 1500–1800 °C using Joule heating in one atmosphere 0.1%–1% oxygen/argon gas mixtures for times up to 15 min. Possible mechanisms based on the resulting complex time, temperature, and oxygen partial pressure dependencies are discussed. The carbides formed porous and intergranular oxides. Oxidation resistance was improved upon a continuous external scale formation. The diborides formed dense external scales and exhibited better oxidation resistance compared to the carbides. This improvement was attributed to the formation of liquid boria. Both compositions showed an unexpected reduction in material consumption at 1800 °C for all times tested, compared to results at lower temperatures. An in-depth analysis of the composition and morphology of the oxide scale and sub-surface regions for specimens tested at 1800 °C revealed that the formation of denser group IV-rich (Hf, Zr, Ti) oxides mitigated the formation of the otherwise detrimental liquid-forming group V (Ta, Nb) oxides, leading to the improved oxidation resistance. [ABSTRACT FROM AUTHOR]

The natural aroma compound (+)-nootkatone was obtained in selective conversions of up to 74 mol% from inexpensive (+)-valencene substrate by using a comparatively greener biocatalytic process developed based on modifications of the previously published Firmenich method. Buffer identity and concentration, pH, temperature and downstream work-up procedures were optimized to produce a crude product in which >90 % of (+)-valencene had been converted, with high chemoselectivity observed for (+)-nootkatone production. Interestingly, the biotransformation was carried out efficiently at temperatures as low as 21 ºC. Surprisingly, the best results were obtained when an acidic pH in the range of 3–6 was applied, as compared to the previously published procedure in which it appeared to be necessary to buffer the pH optimally and fixed throughout at 8.5. Furthermore, there was no need to maintain a pure oxygen atmosphere to achieve good (+)-nootkatone yields. Instead, air bubbled continuously at a low rate through the reaction mixture via a submerged glass capillary was sufficient to enable the desired lipoxygenase-catalyzed oxidation reactions to occur efficiently. No valencene epoxide side-products were detected in the organic product extract by a standard GCMS protocol. Only traces of the anticipated corresponding α- and β-nootkatol intermediates were routinely observed. [Display omitted] • A greener method was developed to produce (+)-nootkatone biocatalytically. • An unprecedentedly high conversion of 74 mol% (+)-nootkatone was obtained from inexpensive valencene. • Surprisingly, soy bean LOX isozymes were found to perform optimally in the pH range 4-6 and catalyzed the desired reaction at a pH as low as 2. [ABSTRACT FROM AUTHOR]

The skin is made up of different layers with various gradients, which maintain a complex microenvironment, particularly in terms of oxygen levels. However, all types of skin cells are cultured in conventional incubators that do not reproduce physiological oxygen levels. Instead, they are cultured at atmospheric oxygen levels, a condition that is far removed from physiology and may lead to the generation of free radicals known to induce skin ageing. This review aims to summarize the current literature on the effect of physiological oxygen levels on skin cells, highlight the shortcomings of current in vitro models, and demonstrate the importance of respecting skin oxygen levels. We begin by clarifying the terminology used about oxygen levels and describe the specific distribution of oxygen in the skin. We review and discuss how skin cells adapt their oxygen consumption and metabolism to oxygen levels environment, as well as the changes that are induced, particularly, their redox state, life cycle and functions. We examine the effects of oxygen on both simple culture models and more complex reconstructed skin models. Finally, we present the implications of oxygen modulation for a more therapeutic approach. [Display omitted] • Skin cells are physiologically in a microenvironment poor in oxygen called physioxia. • Skin physioxia is not taken into account in in vitro models. • Physioxia affects cutaneous cell metabolism. • Physioxia impacts skin cell proliferation, differentiation and senescence. • Physioxia modulates skin cell migration, pigmentation and angiogenesis. [ABSTRACT FROM AUTHOR]

Modified atmosphere package (MAP), as a practical, economic, and easy to operate food package technique, has experienced a rapid development in both scientific and industrial communities. In recent years, given the superiority of super-atmospheric O2 (SO) MAP in preserving fruits and vegetables relative to low O2 and/or high CO2 MAP, SO MAP is back on the radar of researchers. This paper systematically reviews recent development on application of SO MAP and improved strategies to fruit and vegetable preservation in the last 15 years, possible mechanisms concerning their positive and negative effects, and challenges and future perspectives for SO MAP. The present work can provide a theoretical basis and technique reference for achieving a better effectiveness on fruit and vegetable preservation in the practical application. [ABSTRACT FROM AUTHOR]

The early Cambrian witnessed an increase in metazoan ecosystem complexity, likely linked to enhanced oxygen and nutrient availability. However, while improved stratigraphic and geochemical records suggest that the Cambrian explosion occurred under highly dynamic redox conditions, mechanistic links to nutrient availability and early Cambrian evolutionary innovations are poorly constrained. Here, we report paleoredox and nutrient data for two drill cores documenting late Cambrian Stage 2 to Stage 3 (ca. 522–514 Ma) strata from the Yangtze block, South China. The development of water-column euxinia during Cambrian Stage 2 led to extensive recycling of P, fueling elevated primary production and hence an increase in atmospheric and shallow-marine oxygen concentrations. The resulting expansion of oxygenated shelf area promoted sedimentary P retention and, in combination with a diminished supply of P from upwelling, drove a transition to oligotrophic shallow-marine conditions during Cambrian Stage 3. Reduced primary production and limited water-column oxygen consumption allowed for the stabilization of oxygenated continental shelf habitats that supported a burgeoning biotic complexity. [ABSTRACT FROM AUTHOR]

Sodium borohydride induces the oxidative expansion of the imine derived from isatin and phenylethylamine to form 3-phenethylquinazoline-2,4(1H,3H)-dione. It has been proposed that this transformation occurs by in situ formation of hydroperoxyl anions by a reaction between sodium borohydride and atmospheric oxygen. To contribute to understanding this oxidative expansion, the reaction between the imine derived from isatin and phenylethylamine with hydrogen peroxide was studied in this work. From this reaction, 3-phenethylquinazoline-2,4(1H,3H)-dione was isolated and two by-products were identified: N-phenethyl-2-(3-phenethyl-ureido)-benzamide and methyl(2-(phenethylcarbamoyl)phenyl)carbamate. This article analyses the structure of these by-products and proposes a mechanism that explains the reaction. It was established that the reaction of the imine derived from isatin and phenylethylamine with hydrogen peroxide produces a mixture of three compounds: 3-phenethylquinazoline-2,4(1H,3H)-dione, N-phenethyl-2-(3-phenethyl-ureido)-benzamide and methyl(2-(phenethylcarbamoyl)phenyl)carbamate. A reaction mechanism is proposed that explains this behaviour [ABSTRACT FROM AUTHOR]

The corrosion of SiCf/SiC composites in gas environment threatens their long‐term service in aeroengines as hot‐end structure components. Addition of corrosion‐resistant phases into SiC matrix is a potential strategy to improve the service performance of SiCf/SiC materials. Here, AlN added SiC ceramics were prepared by reactive melt infiltration, and the effect of AlN phase on the oxidation resistance of the ceramics was emphasized. The oxidation tests were performed in dry oxygen and water oxygen atmospheres at 1100°C–1300°C, respectively. The oxidation mechanism was discussed based on the microstructure evolution of the oxide layer. The results show that the oxide layer is composed of aluminum silicate glass and Al2O3 flakes dispersedly distributed in the glass phase. As the temperature rises, the oxide layer gradually grows and thickens. Finally, a smooth and dense protective layer could be formed on the surface of ceramics to resist oxidation. This study can provide a profound insight to construct SiCf/SiC composites with excellent oxidation resistance. [ABSTRACT FROM AUTHOR]

A new, Earth System Model of Intermediate Complexity, DCESS II, is presented that builds upon, improves and extends the Danish Center for Earth System Science (DCESS) Earth System model (DCESS I). DCESS II has considerably greater spatial resolution than DCESS I while retaining the fine, 100 m vertical resolution in the ocean. It contains modules for the atmosphere, ocean, ocean sediment, land biosphere and lithosphere and is designed to deal with global change simulations on scales of years to millions of years while using limited computational resources. Tracers of the atmospheric module are temperature, nitrous oxide, methane (12,13C isotopes), carbon dioxide (12,13,14C isotopes) and atmospheric oxygen. For the ocean module, tracers are conservative temperature, absolute salinity, water 18O, phosphate, dissolved inorganic carbon (12,13,14C isotopes), alkalinity and dissolved oxygen. Furthermore, the ocean module considers simplified dynamical schemes for large-scale meridional circulation and sea-ice dynamics, stratification-dependent vertical diffusion, a gravity current approach to the formation of Antarctic Bottom Water and improvements in ocean biogeochemistry. DCESS II has two hemispheres with six zonal-averaged atmospheric boxes and twelve ocean boxes distributed across the Indian-Pacific, the Atlantic, the Arctic and the Southern Oceans. A new, extended land biosphere scheme is implemented that considers three different vegetation types whereby net primary production depends on sunlight and atmospheric carbon dioxide. The ocean sediment and lithosphere model formulations are adopted from DCESS I but now applied to the multiple ocean and land regions of the new model. A model calibration was carried out for the pre-industrial climate and model steady-state solutions were compared against available modern-day observations. For the most part, calibration results agree well with observed data, included excellent agreement with ocean carbon species. This serves to demonstrate model utility for dealing with the global carbon cycle. Finally, two idealized experiments were carried out in order to explore model performance. First, we forced the model by varying Ekman transport out of the model Southern Ocean, mimicking the effect of Southern Hemisphere westerly wind variations and second, we imposed freshwater melting pulses from the Antarctic ice sheet on to the model Southern Ocean shelf. Changes in ocean circulation and in the global carbon cycle found in these experiments are reasonable and agree with results for much more complex models. Thus, we find DCESS II to be a useful and computational-friendly tool for simulations of past climates as well as for future Earth System projections. [ABSTRACT FROM AUTHOR]

The synthesis of substituted pyrazines from readily available methyl aryl/heteroaryl ketones and 1,2‐diamines was achieved using highly stable and reusable ferrite‐stabilized copper nanoparticles (Fe3O4‐CuO) as a catalyst. The reaction proceeds through a cascade imine formation–oxidative cyclization method under an oxygen atmosphere. The nanocatalysts were readily recovered and reused up to three consecutive cycles without any significant decrease in particle size, catalytic activity and reaction yield, as evidenced by analytical techniques such as transmission electron microscopy (TEM) and powder X‐ray diffraction (PXRD). The synthesized pyrazines exhibited photophysical behaviour, displayed large Stokes shifts, and were explored as fluorescent probes for the sensitive as well as selective "turn‐off" detection of iron with a limit of detection of 0.63 μM. The sensing method is also useful for the quantification of iron in spiked water samples. Furthermore, the application of luminescent pyrazines as fluorescent ink was successfully demonstrated. [ABSTRACT FROM AUTHOR]

To improve the strength of Al 2 O 3 specimens produced using the water-stabilized plasma spraying technique (WSPSAO), this study investigates the effect of structural modification on the mechanical properties of WSPSAO using the Al-Cu-O reaction between the metal, atmospheric oxygen, and base material. A Cu-powder layer is applied to the specimen surface, melted, and oxidized at high temperatures. It penetrates into the specimen, resulting in significant microstructural modification deep in the specimen. After modification, uniaxial Al 2 O 3 , CuO, Cu 2 O, and CuAl 2 O 4 are formed in the specimen, resulting in a denser and more uniform structure than that of the original material. The bending strength of the coated surface is 145 MPa, and that on the opposite side of the coated surface is 118 MPa, which is 130%–180% higher than the original strength of the base material. [ABSTRACT FROM AUTHOR]

Atmospheric oxygen levels are traditionally viewed to have been relatively stable throughout Earth's history with several-step increases. Emerging evidence, however, suggests extremely dynamic atmospheric oxygen levels through large swaths of Earth's history. Here, we provide a new perspective on atmospheric oxygen evolution using a dynamical analysis to explore the relative importance of previously proposed feedbacks on the global oxygen and carbon cycles. Our results from a stochastic analysis of oxygen mass balance in this framework suggest there are multiple steady states for atmospheric oxygen, but only three stable states. One stable state under anoxic conditions (<10−5 present atmospheric level (PAL)), one at low (~10−3to 10−2 PAL), and one near modern value atmospheric oxygen levels. Our findings also suggest two unstable states (tipping points) for atmospheric oxygen: one around 10−5 and another one around 10−1 PAL. Atmospheric oxygen levels tend to be stable under anoxic, low oxygen, and near-modern conditions, with two unstable states at around 10−5 and 10−1 present atmospheric level, according to the results from a stochastic analysis of oxygen mass balance. [ABSTRACT FROM AUTHOR]

Bismuth ferrite (BiFeO3)‐based high‐temperature piezoelectric ceramics have high Curie temperatures and excellent thermal stability; however, their applications are limited by inadequate piezoelectric performance due to large coercive fields and high leakage conduction. This study investigates the impact of MnO2 doping on the phase transition, defect structure, domain morphology, as well as the dielectric, ferroelectric, and electrical conduction behaviors of 75BiFeO3–25BaTiO3 ceramics sintered under an oxygen atmosphere. A structural transformation from distorted rhombohedral to pseudo‐cubic symmetry was observed with increasing MnO2 content, accompanied by domain fragmentation. MnO2 doping at an appropriate level inhibited defects such as Fe′Fe$\ {\mathrm{F}}{{{\mathrm{e^{\prime}}}}_{{\mathrm{Fe}}}}$ and VO2−⋅⋅$V_{{{{\mathrm{O}}}^{{\mathrm{2}} - }}}^{\centerdot \centerdot }$. Regarding electrical properties, the reduction in rhombohedral distortion and enhancement in the pseudo‐cubic phase after MnO2 doping resulted in decreased remanent polarization and electrostrain, which could potentially hinder piezoelectric response. However, appropriate MnO2 doping effectively reduced leakage conduction, significantly enhancing the poling efficiency of the ceramics. The maximum d33 value of 107 pC/N and kp of 0.36 were achieved at an MnO2 doping content of 0.1 wt.%. Excessive MnO2 addition may generate 2Mn′Ti−VO2−⋅⋅${\mathrm{2M}}{{{\mathrm{n^{\prime}}}}_{{\mathrm{Ti}}}}-V_{{{{\mathrm{O}}}^{{\mathrm{2}} - }}}^{\centerdot \centerdot }$ defect dipoles, as indicated by increased coercive field (Ec) and dielectric loss. The observed increase in high‐temperature resistivity with MnO2 content is primarily attributed to reduced grain size and increased concentration of mobile defects. This study provides valuable insights for further research on the application of 75BiFeO3–25BaTiO3 systems in high‐temperature piezoelectric devices. [ABSTRACT FROM AUTHOR]

Introduction: Curing is a critical process that determines the sensory quality of cigars. The impact of oxygen on cigar curing and the mechanisms by which it regulates microbial changes affecting cigar quality are not well understood. Methods: In this study, we selected handmade cigars from the same batch and conducted curing experiments in environments with varying oxygen concentrations (equivalent to 0.1%, 6-12, and 15% of atmospheric oxygen concentration). We collected samples over 60 days and analyzed the distribution of microbial communities using high-throughput sequencing. Combined with the analysis of total sugars, proteins, flavor substances, and other chemical compounds, we elucidated how different oxygen concentrations affect the cigar curing process, influence microbial community succession, and ultimately impact cigar quality. Results: Our results revealed significant differences in bacterial community composition under different oxygen conditions. Under aerobic conditions, Cyanobacteria were the dominant bacteria, while under oxygen-limited conditions, Staphylococcus and Corynebacterium predominated. As oxygen concentration decreased, so did the richness and diversity of the bacterial community. Conversely, oxygen concentration had a lesser impact on fungi; Aspergillus was the dominant genus in all samples. We also found that Enterococcus showed a positive correlation with aspartic acid, alanine, and 4-aminobutyric acid and a negative correlation with cysteine. Cigars cured at 15% oxygen concentration for 60 days exhibited optimal quality, particularly in terms of flavor richness and sweetness. Discussion: These findings suggest that oxygen concentration can alter cigar quality by regulating aerobic and anaerobic microbial community succession. The relationship between specific microbial communities and flavor compounds also provides a theoretical reference for developing artificial control technologies in the cigar curing process. [ABSTRACT FROM AUTHOR]

This paper presents the effects of annealing on the phase and chemical composition, surface morphology, structure, substructure, and optical properties of SnS films obtained using the nanoink spraying method based on a suspension of nanoparticles. SnS nanoparticles were synthesized in an aqueous ammonia solution using triethanolamine. After the ink was applied to the glass substrates, the samples were annealed at 150, 200, 250, 300, 350, 400, 450, and 500 °C for 30 min in a mixture of argon and oxygen atmosphere. Thin layers of tin sulfide were studied using energy-dispersive EDX, X-ray diffraction analysis, SEM microscopy, Raman spectroscopy, and optical spectroscopy. The films are nanocrystalline and contain an orthorhombic SnS phase. In the films annealed at a temperature Ta ≥ 450 °C, tin oxide was detected diffractometrically. These studies also explored the determination of the main structural parameters of the films, such as the texture, period of the crystal lattice, sizes of the coherent scattering regions, and the level of microdeformations depending on the annealing temperature. The optimal conditions for the annealing of the films were investigated. [ABSTRACT FROM AUTHOR]

In this paper, a nonlinear aerothermoelastic analysis of a deployable control fin subjected to Mach 7 hypersonic flow is presented. The fin consists of the inboard and outboard parts joined together with a revolute joint having freeplay nonlinearity. The fin is assumed to be a whole movable fin and, hence, is connected to an actuator having nonlinear stiffness characteristics. The fin is made of the annealed Ti-6Al-4V material, which has temperature-dependent physical, mechanical, and thermal properties. To perform a coupled fluid-thermal-structural interaction analysis, a delayed detached eddy simulation method-based fluid dynamics solver is strongly coupled to a finite element method-based thermoelastic solver in the time domain. The effects of fin aspect ratio, thickness ratio, free stream dynamic pressure, and structural damping on the flow field as well as structural dynamics characteristics are investigated and presented. Since the flow is highly compressible at Mach 7 and the temperature rise is observed to be sufficient to excite the vibrational modes of the diatomic nitrogen and oxygen of the atmosphere, the air is modeled as a calorically imperfect gas. Shock interactions and concentrated vortices originating from various high-thickness locations at the joint as well as root sections are observed. It is found that at high altitudes, the contribution of the torsional mode is significant in fin deformation, whereas, at low altitudes, the bending mode contribution is higher. Also, it is shown that the fin aspect ratio, thickness ratio, and damping ratio have significant effects on the fin stability and performance. [ABSTRACT FROM AUTHOR]

The effects of vacuum and oxygen annealing on Sr2-xNbxIrO4 samples have been systematically investigated. The annealing under vacuum leads to an enhanced insulating state of the Sr2-xNbxIrO4 compounds, which could be due to the evaporation of oxygen atoms which breaks the superexchange interaction between Ir and O ions. The annealing under oxygen atmosphere results in substantial straightening of the in-plane Ir–O–Ir bond and rapid depression of the canted antiferromagnetic ordering state. Importantly, the insulator-to-metal transition has been achieved by oxygen annealing of the Sr2-xNbxIrO4 samples, which could be due to the enhanced hybridization of Ir 5d orbitals with the neighboring O 2p orbitals. The present results suggest that the annealing treatment could be an effective way for exploring of novel physical phenomena in Sr2IrO4 and related compounds. [ABSTRACT FROM AUTHOR]

This study analyzes the oxidation behavior of FeCrAl–(0.0, 0.5, 1.0, 2.0, and 4.0) wt% Sc alloys prepared through vacuum hot‐press sintering in a water vapor environment. Sc diffuses via short‐circuit diffusion from the oxide scale/alloy interface to the oxide scale surface. Subsequently, Sc is segregated at the aluminum oxide scale interface, preventing Al ions from diffusing outward to combine with the oxygen in the water vapor and reducing the growth rate of the oxide scale. Compared to a pure oxygen atmosphere, the water vapor atmosphere affects the adhesion of the oxide scale, shedding the oxide scale and leading to secondary oxidation. Sc doping transforms the oxide scale from a state of easily curved, poorly bonded, and full voids into a flat, bonded, dense, and protective scale. A dopant content of 0.5 wt% Sc is low and has a minor effect on the oxidation resistance of FeCrAl alloys. Samples containing 2.0 and 4.0 wt% Sc are excessively doped, causing considerable internal oxidation. In this experiment, 1.0 wt% Sc doping is found to be the most appropriate, demonstrating a low mass gain of 2.59 ± 0.12 mg cm−2 and a slow oxidation rate (Kp = 0.7131 mg cm−2 · hn). [ABSTRACT FROM AUTHOR]

The effects of vacuum and oxygen annealing on Sr2-xNbxIrO4 samples have been systematically investigated. The annealing under vacuum leads to an enhanced insulating state of the Sr2-xNbxIrO4 compounds, which could be due to the evaporation of oxygen atoms which breaks the superexchange interaction between Ir and O ions. The annealing under oxygen atmosphere results in substantial straightening of the in-plane Ir–O–Ir bond and rapid depression of the canted antiferromagnetic ordering state. Importantly, the insulator-to-metal transition has been achieved by oxygen annealing of the Sr2-xNbxIrO4 samples, which could be due to the enhanced hybridization of Ir 5d orbitals with the neighboring O 2p orbitals. The present results suggest that the annealing treatment could be an effective way for exploring of novel physical phenomena in Sr2IrO4 and related compounds. [ABSTRACT FROM AUTHOR]

Hydrogen (H 2) is widely acknowledged as a promising, sustainable, and environmentally friendly energy carrier, offering numerous environmental benefits over conventional fossil fuels. However, the advancement of this technology is severely hindered by the scarcity of effective and robust catalysts for hydrogen evolution (HER) and oxygen evolution (OER) reactions activity. This study marks the inaugural fabrication of a hybrid tri-metallic electrocatalyst, termed MnCoCu–P, through hydrothermal synthesis. Subsequently, the catalyst undergoes atmospheric O 2 plasma surface activation, aiming to amplify the efficiency of water splitting. The novel atmospheric O 2 plasma-activated MnCoCu–P electrode outperforms the reported classic metal phosphides, and it outperformed the compared commercial Pt/C and RuO 2 benchmark catalysts with outstanding performances of 0.488 and 1.20 V towards HER and OER at 1000 mA/cm2, respectively. Additionally, the MnCoCu–P (5 min) catalyst Faradic efficiency was calculated under alkaline conditions in 1.0 M KOH, and both the produced gas H 2 and O 2 match the theoretical and experimental calculated values well, indicating a high efficiency of almost 100%. In the 2-E system, MnCoCu–P (5 min)‖MnCoCu–P (5 min) demonstrated remarkable performance by attaining a current density of 1000 mA/cm2 at low total cell voltages of 1.93 V and outperforming the benchmark Pt/C‖RuO 2 electrode system. On the other hand, the MnCoCu–P electrode possesses excellent activity under industrial conditions at 6.0 M @ 60 °C exhibited 1.89 V at 1000 mA/cm2 and performs well in natural water systems. Moreover, the 5 min O 2 plasma-treated MnCoCu–P‖MnCoCu–P electrodes showed improved activity in all the pH solutions which makes it one of the potential candidates for commercial application in the future. [Display omitted] • Trimetallic MnCoCu–P catalyst was successfully fabricated via one-step hydrothermal approach. • The 5 min O 2 plasma-treated MnCoCu–P catalyst showed excellent electrocatalytic activity. • MnCoCu–P (5 min)‖MnCoCu–P (5 min) showed enhanced activity under industrial conditions. • MnCoCu–P (5 min) electrode exhibits comparable performance in universal pH and natural water. [ABSTRACT FROM AUTHOR]

In many places in the world, groundwater contains arsenic compounds. To purify water containing arsenic effectively, arsenic (III) compounds must be oxidised. The subject of this study is oxidation of arsenic (III) compounds in an aqueous solution in a flow column mode. The industrial arsenic oxidation technology involving aggressive oxidising agents such as chlorine or ozone, which is used most commonly today, has a number of serious disadvantages. The most problematic include extremely high risks for human health and the environment, the process cost and overall complexity. Catalytic oxidation of arsenic (III) compounds with atmospheric oxygen is an alternative that is free from the above disadvantages. Previously, the author studied the process of effective catalytic oxidation of arsenic (III) on the new active manganese dioxide (NADM) he had synthesised. Later, however, it turned out that NADM has a significant drawback: during prolonged flow column stops, its catalytic activity drops sharply. This work proposes both a theoretical justification for and a solution to this problem. A new calcium-doped active manganese dioxide NADM-Ca0.5 was synthesised. It was shown that NADM-Ca0.5 demonstrates high catalytic activity towards arsenic (III). The fact that flow column long stops do not affect its catalytic activity was also experimentally confirmed. On the basis of the study results, some theoretical aspects are also discussed of the mechanism for catalytic oxidation of arsenic (III) with oxygen on active manganese dioxide in an aqueous solution. For successful industrial implementation of the technology for catalytic oxidation of arsenic (III) compounds on NADM-Ca0.5, experimental work on pilot plants in the field is required and further laboratory research is needed in order to develop a detailed theoretical basis for the mechanism of catalytic oxidation of arsenic in aqueous solutions. The results of this work are of interest for both industrial companies specialising in water purification from arsenic compounds, and scientists and researchers studying catalytic oxidation of arsenic (III), as well as heterogeneous catalytic oxidation with oxygen in general. [ABSTRACT FROM AUTHOR]

It is a great challenge to prepare Pb(Mg 1/3 Nb 2/3)O 3 –PbTiO 3 (PMN-PT) ceramics of very high transparency with only oxygen atmosphere pressureless sintering process. To address this issue, this work proposed an optimal low-cost two-step oxygen atmosphere sintering process with a first step at high temperature (T 1) for minutes, followed by a second step at lower temperature (T 2) for hours without applied pressure. High transmittance of 70 % in the near-infrared wavelength was achieved by our novel two-step process, which far exceeds the performance of PMN–PT ceramics prepared by only oxygen atmosphere sintering process reported in the past and demonstrates comparable performance compared to the costly hot-pressing sintering process. Meanwhile, it shows a high quadratic electro-optic (EO) coefficient of 42.1 × 10−16 m2 V−2, which is meaningful for applications in EO devices. Furthermore, the effect of the temperature difference between the first and second sintering step on the microstructure, transmittance, domain structure, ferroelectric and dielectric property, and polarization switching were discussed. The enhanced transparency is mainly attributed to the higher relative density, and weaker photoluminescence effect with lesser light absorption loss at optimal T 1 -T 2. The improved EO property is due to greater polarization response originating from the interaction of defect dipoles and nanodomains. Such a process should facilitate the cost-effective preparation of other transparent electro-optic materials for practical applications. [ABSTRACT FROM AUTHOR]

Oxide targets are crucial materials for transparent conducting oxide (TCO) thin films used in optoelectronic devices. In this study, neodymium-doped indium zinc oxide (NdIZO) ceramic targets were prepared using an advanced pressureless oxygen atmosphere sintering process. By optimizing the experimental conditions, the best sintering parameters were obtained, resulting in dense, fine-grained, and uniformly microstructured NdIZO targets. The influence mechanism of different Nd doping concentrations on the phase composition, microstructure evolution, and electrical properties of the targets during the process of oxide composite powder, green body shaping, and sintering densification was analyzed in detail. The results showed that the pretreatment of the composite powder improved its dispersibility, and sintering activity. The NdIZO-2 target with an atomic ratio of Nd:In:Zn = 0.02:1:1, fabricated under optimal conditions, exhibited high density of 99.8 %, low resistivity of 5.2 mΩ cm, and an average grain size of about 3.9 μm, thereby demonstrating the best comprehensive performance. Moreover, the sputtered films prepared using NdIZO-2 targets also showed excellent properties with transmittance (T) of 88.1 %, electron mobility (μ e) of 31.5 cm2/Vs, and resistivity (ρ) of 7.5 × 10−3 Ω cm. This work provides theoretical support for the preparation of high-quality indium zinc oxide (IZO) ceramic targets and their application in high-performance optoelectronic thin film devices. [ABSTRACT FROM AUTHOR]

This article presents a new method for synthesizing polysubstituted imidazoles, which are compounds with various pharmaceutical and biological applications. The authors optimized the reaction conditions using iron catalysis and oxygen as the sole oxidant, resulting in high yields of the desired products. The protocol provides a straightforward and efficient method for synthesizing polysubstituted imidazole compounds using easily available starting materials. The article also includes chemical data for various compounds, including their yields, physical properties, and nuclear magnetic resonance (NMR) spectra. [Extracted from the article]

Infectious and foodborne diseases pose significant global threats, with devastating consequences in low- and middle-income countries. Ozone, derived from atmospheric oxygen, exerts antimicrobial effects against various microorganisms, and degrades fungal toxins, which were initially recognized in the healthcare and food industries. However, highly concentrated ozone gas can be detrimental to human health. In addition, ozonated water is unstable and has a short half-life. Therefore, ultrafine-bubble technology is expected to overcome these issues. Ultrafine bubbles, which are nanoscale entitles that exist in water for considerable durations, have previously demonstrated bactericidal effects against various bacterial species, including antibiotic-resistant strains. This present study investigated the effects of ozone ultrafine bubble water (OUFBW) on various bacterial toxins. This study revealed that OUFBW treatment abolished the toxicity of pneumolysin, a pneumococcal pore-forming toxin, and leukotoxin, a toxin that causes leukocyte injury. Silver staining confirmed the degradation of pneumolysin, leukotoxin, and staphylococcal enterotoxin A, which are potent gastrointestinal toxins, following OUFB treatment. In addition, OUFBW treatment significantly inhibited NF-κB activation by Pam3CSK4, a synthetic triacylated lipopeptide that activates Toll-like receptor 2. Additionally, OUFBW exerted bactericidal activity against Staphylococcus aureus, including an antibiotic-resistant strain, without displaying significant toxicity toward human neutrophils or erythrocytes. These results suggest that OUFBW not only sterilizes bacteria but also degrades bacterial toxins. [ABSTRACT FROM AUTHOR]

Until the late 20th century, the idea of identifying wildfires in deep time was not generally accepted. One of the basic problems was the fact that charcoal-like wood fragments, so often found in sedimentary rocks and in coals, were termed fusain and, in addition, many researchers could not envision wildfires in peat-forming systems. The advent of Scanning Electron Microscopy and studies on modern charcoals and fossil fusains demonstrated beyond doubt that wildfire residues may be recognized in rocks dating back to at least 350 million years. Increasing numbers of studies on modern and fossil charcoal assemblages from the 1970s through the 1990s established the potential importance of wildfires in the fossil record, using Carboniferous examples in particular. Since the 1990s, extensive progress has been made in understanding modern wildfires and their byproducts. New techniques to study ancient charcoals have allowed considerable progress to be made to integrate modern and ancient fire studies, both before and after the evolution of mankind. Four important developments have made a reassessment of Carboniferous wildfires necessary: the recognition of the role of atmospheric oxygen in controlling the occurrence of wildfire; the development of new microscopical techniques allowing more detailed anatomical data to be obtained from charcoal; the integration of molecular studies with the evolution of fire traits; and new developments in or understanding of post-fire erosion/deposition systems. [ABSTRACT FROM AUTHOR]

The oxide thin‐film transistors (TFTs) with ultrathin (5 nm) crystalline In2O3 channels formed by an atomic layer deposition method are fabricated. The ultrathin In2O3 films are formed at a deposition temperature of 300 °C using (3‐(dimethylamino)propyl)dimethylindium as the indium precursor and ozone as the oxidizing agent. The postannealing is performed in an oxygen atmosphere for 2 h at 300 °C. The scaling behavior of the field‐effect mobility (μFE) is investigated as a function of the channel length (Lch). As Lch increases from 5 to 160 μm, the average μFE is measured and found to increase from 20.2 to 33.6 cm2 V−1 s−1. It shows the average device properties of subthreshold swing of 0.32 V dec−1, turn‐on voltage of −5.5 V, and on/off current ratio of 107. To understand this trend, the transmission line model is utilized to extract the resistance components present across the channel quantitatively. The analyses reveal that among the components comprising the total resistance, the fraction of Rc increases as Lch becomes shorter. Thus, Rc emerges as a dominant parameter that determines μFE. In this regard, the results have technical significance in vertical TFTs and high‐resolution applications in which predictable scaling matters. [ABSTRACT FROM AUTHOR]

This study describes iron (Fe) pipestems formed around and within root channels during the development of a homogeneous unripe sulfidic sediment into a ripe soil where redox‐ or pH‐active elements segregate. Pipestems and adjacent soil material samples were characterised by chemical and mineralogical analyses and scanning electron microscopy (SEM) associated with energy dispersive spectroscopy (EDS). Pipestems occurred at 60–190 cm and at 30–130 cm in a young Finnish soil and a more mature Australian soil, respectively, while sulfidic materials were found below 170–180 cm. The pipestems consisted of mineral grains cemented together by Fe precipitate. There was an up to 24‐fold enrichment of Fe and an up to 13‐fold enrichment of sulfur (S) in the Finnish pipestems compared to the adjacent soil material, whereas the corresponding enrichment in the Australian soil was up to 27‐fold for Fe and up to 8‐fold for S. In the Australian pipestem matrices, the Fe concentration was as high as 40% compared to 14% in the Finnish ones. It was estimated that about 70 ton ha−1 S had been mobilised from the sulfidic material in the Finnish soil at the depth of 50–150 cm. Part of S has leached out but a substantial amount remained in the soil constituting the stock of retained acidity. Almost all pipestems contained a new solid phase precipitated within the former cortex cells of the plant roots. In the Finnish samples, this precipitate consisted of jarosite and schwertmannite. After oxidative exhaustion of sulfidic material in the surrounding soil, these metastable minerals are gradually hydrolysed, associated with leaching of S. In the mature Australian soil, most of these minerals had already been transformed to goethite. Pipestems formed after roots in unripe soil are sites for synthesis and hydrolysis of minerals and serve as routes for atmospheric oxygen into the reduced subsoil and for soluble reaction products to exit the soil. Pipestems have an important role in the ripening of the soil profile. [ABSTRACT FROM AUTHOR]

Understanding the interactions in hybrid systems based on graphene and functional oxides is crucial to the applicability of graphene in real devices. Here, we present a study of the structural defects occurring on graphene during the early stages of the growth of CoO, tailored by the electronic coupling between graphene and the substrate in which it is supported: as received pristine graphene on polycrystalline copper (coupled), cleaned in ultra-high vacuum conditions to remove oxygen contamination, and graphene transferred to SiO2/Si substrates (decoupled). The CoO growth was performed at room temperature by thermal evaporation of metallic Co under a molecular oxygen atmosphere, and the early stages of the growth were investigated. On the decoupled G/SiO2/Si samples, with an initial low crystalline quality of graphene, the formation of a CoO wetting layer is observed, identifying the Stranski-Krastanov growth mode. In contrast, on coupled G/Cu samples, the Volmer-Weber growth mechanism is observed. In both sets of samples, the oxidation of graphene is low during the early stages of growth, increasing for the larger coverages. Furthermore, structural defects are developed in the graphene lattice on both substrates during the growth of CoO, which is significantly higher on decoupled G/SiO2/Si samples mainly for higher CoO coverages. When approaching the full coverage on both substrates, the CoO islands coalesce to form a continuous CoO layer with strip-like structures with diameters ranging between 70 and 150 nm. [ABSTRACT FROM AUTHOR]

Wildfires significantly affect climate and environmental changes, closely tied to extreme weather responses. Vegetation combustion emits greenhouse gases (CO2, CH4, CO), warming the climate. Climate shifts, in turn, impact vegetation growth, altering combustible material types and quantities, thus affecting wildfire intensity, duration, and frequency. Wildfires profoundly affect ecosystems, influenced by factors like atmospheric oxygen and climate. Their combustion gases impact climate and vegetation growth. Recent advancements in studying ancient wildfires include analyzing nanoparticles as key indicators. This study discovered six types of nanoparticles in ancient wildfire remains, with sizes ranging from 50 nm to 500 nm and diverse compositions including elements such as C, O, Mg, Al, Ti, Fe, S, Ca, and P. These findings indicate that wildfires generate a variety of nanoparticles, offering new insights into ancient fire events. Elemental analysis revealed low magnesium but high calcium and aluminum levels, suggesting a warm, humid paleoclimate during these fires. The presence of high Ti-O ratios and carbon-rich nanoparticles points to ground fires with incomplete combustion. This research underscores the significance of nanoparticles in understanding the history and characteristics of ancient wildfires. [ABSTRACT FROM AUTHOR]

In the current era, it has become essential to move toward highly efficient and low-emission engines as the norms for automobile emissions are very stringent and closely monitored; moreover, it also tends to be more strictly regulated in the future. The aim of this experimental work is to optimize engine efficiency as well as reduce emissions to the maximum using oxygen-enriched air. An onboard oxygen generator can provide oxygen-enriched air instead of an oxygen cylinder, as the latter one is prone to cause safety issues. In this experimental study, oxygen is obtained through generator and is sent to the engine's intake manifold, where the atmospheric air merges with it. The parameters of combustion, performance, and emission of this oxygen-enriched air were examined in a constant-speed compression ignition engine. The result shows that the engine's brake thermal efficiency increased by 5.4% at 25% of brake power as compared to the thermal efficiency attained in atmospheric air combustion. Similarly, brake-specific fuel consumption also decreased in the oxygen-enriched combustion process. The emissions of hydrocarbon and carbon monoxide also decreased to 18.8% and 33.3%, respectively, for 25% of the brake power; notably, the smoke emissions reduced drastically to 32% at the same brake power. The oxides of nitrogen emission, however, increased with the air's oxygen content. [ABSTRACT FROM AUTHOR]

Pyridinic nitrogen vacancy in carbon nitride for photo-self Fenton-like purification of organic contaminants. [Display omitted] • Carbon nitride with pyridinic nitrogen vacancy was successfully prepared. • Pyridinic nitrogen vacancy promotes charge transfer and activating O 2 into H 2 O 2. • Pyridinic nitrogen vacancy accelerates carbon nitride to adsorb organic contaminants. • Photo-self Fenton-like reaction for photocatalytic degradation of organics. This work reports a carbon nitride with pyridinic nitrogen-vacancy (N 2C V-CN), which purifies organic contaminants via an in-situ photo-self Fenton-like reaction. Experiments and calculations demonstrated that the nitrogen-vacancy induces lone-paired (LP) and symmetry-unpaired electrons, promoting the formation of low-energy LP-π hybridized orbitals and helping to overcome the pairing energy required for oxygen to accept electrons. Furthermore, the nitrogen-vacancy accelerates film and intra-particle diffusion rates of organic contaminants on N 2C V-CN, creating beneficial conditions for reactive oxide species to mineralize organic contaminants. Under sunlight and atmospheric oxygen, a photo-self Fenton-like reaction involving proton-coupled electron transfer occurred on the surface of N 2C V-CN. Furthermore, by integrating photocatalysis with flocculation, about 99.1 % suspended substance, 45.5 % chemical oxygen demand, and 38.4 % biological oxygen demand were reduced from polluted river-water. Constructing N 2C V-CN and understanding its crucial role offer theoretical and methodological insights into the in-situ purification of contaminated water bodies. [ABSTRACT FROM AUTHOR]

Steel slag-based glass ceramic for thermal energy storage was first fabricated by quenching method, and then their high temperature corrosion behavior in the eutectic carbonates and related mechanism have been investigated using X-ray diffraction，Raman spectroscopy and scanning electron microscope techniques. The results show that holding time has a significant influence on the corrosion layer thickness at 800oC. As the holding time was extended, the thickness of the corrosion layer with obvious cracks tended to increase. Further EDS analyses disclosed that the divided corrosive layers along the extended directions of the cracks should be similar in both the compositions and microstructure. Based on these observations, the possible corrosion mechanism was discussed after defining phase structure of nonstoichiometric (Fe 0.35 Al 0.20 Mg 0.44) Ca 0.96 (Fe 0.08 Si 0.70 Al 0.20) 2 O 6.12 as a combined system of CaMgSi 2 O 6 (Di)-CaFe3+AlSiO 6 (Es)-CaAl 2 Si 2 O 8 (An). Oxygen offered by the molten carbonates salt is regarded to play a critical role in the corrosion process. In an atmosphere rich in oxygen, both Na+ and K+ ions diffused into the diopside can replace Ca2+ and Mg2+, etc. resulting in polyhedral structural reorganization for electrical neutrality. On the other hand, the bonding stability of the cation-oxygen bonds in diopside was proved to be weaker than that in single oxides. These two aspects contribute to the continuous dissolution of Ca2+ and Mg2+, etc. in the molten carbonates salt. [ABSTRACT FROM AUTHOR]

The effect of cyclization degree of nitrogen thermal pretreatment on the radial structure difference of polyacrylonitrile(PAN) oxide fibers is explored. In this paper, PAN fibers were isothermally heated in nitrogen at 170°C, 190°C and 210°C for 0, 10, 20, 30, 40, and 50 min, respectively, so as to obtain pre‐treated fibers with cyclization degrees of 0%, 19.96%, 35.18%, 38.92%, 42.80%, and 53.12%, respectively. The pre‐treated fibers were further stabilized in an oxygen atmosphere. The scanning results show that the radial structure difference of oxide fibers first decreases and then increases with cyclization degree increasing. Through FTIR, SEM and Raman characterization, it is found that this phenomenon is mainly related to the influence of nitrogen thermal pretreatment on oxygen diffusion. Therefore, to improve the thermal stability efficiency of PAN fibers by means of nitrogen thermal pre‐treatment, it is necessary to control the degree of cyclisation, and the appropriate degree of cyclisation in the present work is about 35%. [ABSTRACT FROM AUTHOR]

This study aims to validate the wastewater treatment technique and compare the effectiveness of applying an ozone mixture and atmospheric oxygen in the presence of a catalyst (manganese dioxide) with various dosages. A total of 540 replicates were performed, corresponding to different levels of manganese dioxide concentrations during oxygen and ozone delivery (270 repetitions for each of the experiments). The research was carried out using an experimental setup developed by the authors. The maximum efficiency of oxidation processes was observed within 15–30 min after the start of the treatment cycle. The decrease in the level of chemical oxygen demand within the first quarter-hour during ozone treatment was significantly greater compared to atmospheric oxygen treatment (p ≤ 0.05). The method's efficiency increased to 53% for ozone and 41% for oxygen after 30 min of purification (p ≤ 0.05). Lower catalyst consumption was observed when using an ozone mixture. The tested technology can be recommended for wastewater treatment with high hydrocarbon concentrations. The findings of the study indicated the potential application of ozone treatment with a manganese catalyst for treating wastewater with high hydrocarbon content, thereby fostering the development of more effective water purification methods in the industrial sector. HIGHLIGHTS There is a need to explore new methods for purifying wastewater from hydrocarbons.; The research was carried out using an experimental setup developed by the authors.; The enhanced treatment efficiency was achieved through the application of manganese dioxide.; The tested technology can be recommended for wastewater treatment with high hydrocarbon concentrations.;

ABSTRACT Group‐living in animals comes with a number of benefits associated with predator avoidance, foraging, and reproduction. A large proportion of fish species display grouping behaviour. Fish may also be particularly vulnerable to climate‐related stressors including thermal variation, hypoxia, and acidification. As climate‐related stressors are expected to increase in magnitude and frequency, any effects on fish behaviour may be increased and affect the ability of fish species to cope with changing conditions. Here we conduct a systematic review of the effects of temperature, hypoxia, and acidification on individual sociability and group cohesion in shoaling and schooling fishes. Searches of the published and grey literature were carried out, and studies were included or excluded based on selection criteria. Data from studies were then included in a meta‐analysis to examine broad patterns of effects of climate‐related stressors in the literature. Evidence was found for a reduction in group cohesion at low oxygen levels, which was stronger in smaller groups. While several studies reported effects of temperature and acidification, there was no consistent effect of either stressor on sociability or cohesion. There was some evidence that marine fishes are more strongly negatively affected by acidification compared with freshwater species, but results are similarly inconsistent and more studies are required. Additional studies of two or more stressors in combination are also needed, although one study found reduced sociability following exposure to acidification and high temperatures. Overall, there is some evidence that hypoxia, and potentially other climate‐related environmental changes, impact sociability and group cohesion in fishes. This may reduce survival and adaptability in shoaling and schooling species and have further ecological implications for aquatic systems. However, this synthesis mainly highlights the need for more empirical studies examining the effects of climate‐related factors on social behaviour in fishes. [ABSTRACT FROM AUTHOR]

Exoplanet atmospheres are expected to vary significantly in thickness and chemical composition, leading to a continuum of differences in surface pressure and atmospheric density. This variability is exemplified within our Solar System, where the four rocky planets exhibit surface pressures ranging from 1 nPa on Mercury to 9.2 MPa on Venus. The direct effects and potential challenges of atmospheric pressure and density on life have rarely been discussed. For instance, atmospheric density directly affects the possibility of active flight in organisms, a critical factor since without it, dispersing across extensive and inhospitable terrains becomes a major limitation for the expansion of complex life. In this paper, we propose the existence of a critical atmospheric density threshold below which active flight is unfeasible, significantly impacting biosphere development. To qualitatively assess this threshold and differentiate it from energy availability constraints, we analyze the limits of active flight on Earth, using the common fruit fly, Drosophila melanogaster, as a model organism. We subjected Drosophila melanogaster to various atmospheric density scenarios and reviewed previous data on flight limitations. Our observations show that flies in an N2-enriched environment recover active flying abilities more efficiently than those in a helium-enriched environment, highlighting behavioral differences attributable to atmospheric density vs. oxygen deprivation. [ABSTRACT FROM AUTHOR]

Atmospheric tracers are often used to interpret the local CO 2 budget, where measurements at a single height are assumed to represent local flux signatures. Alternatively, these signatures can be derived from direct flux measurements or by using fluxes derived from measurements at multiple heights. In this study, we contrast interpretation of surface CO 2 exchange from tracer measurements at a single height to measurements at multiple heights. Specifically, we analyse the ratio between atmospheric O 2 and CO 2 (exchange ratio, ER) above a forest. We consider the following two alternative approaches: the exchange ratio of the forest (ER forest) obtained from the ratio of the surface fluxes of O 2 and CO 2 derived from measurements at multiple heights, and the exchange ratio of the atmosphere (ER atmos) obtained from changes in the O 2 and CO 2 mole fractions over time measured at a single height. We investigate the diurnal cycle of both ER signals to better understand the biophysical meaning of the ER atmos signal. We have combined CO 2 and O 2 measurements from Hyytiälä, Finland, during spring and summer of 2018 and 2019 with a conceptual land–atmosphere model to investigate the behaviour of ER atmos and ER forest. We show that the CO 2 and O 2 signals as well as their resulting ERs are influenced by climate conditions such as variations in soil moisture and temperature, for example during the 2018 heatwave. We furthermore show that the ER atmos signal obtained from single-height measurements rarely represents the forest exchange directly, mainly because it is influenced by entrainment of air from the free troposphere into the atmospheric boundary layer. The influence of these larger-scale processes can lead to very high ER atmos values (even larger than 2), especially in the early morning. These high values do not directly represent carbon cycle processes, but are rather a mixture of different signals. We conclude that the ER atmos signal provides only a weak constraint on local-scale surface CO 2 exchange, and that ER forest above the canopy should be used instead. Single-height measurements always require careful selection of the time of day and should be combined with atmospheric modelling to yield a meaningful representation of forest carbon exchange. More generally, we recommend always measuring at multiple heights when using multi-tracer measurements to study surface CO 2 exchange. [ABSTRACT FROM AUTHOR]

The valorization of tannins from forest by‐products is a major opportunity for the sustainable development of the forestry industry. Herein we report the laccase‐mediated polymerization of tannins obtained from an aqueous pine bark extract. The reaction was conducted under an oxygen atmosphere at 50°C for 60 min and followed by UV–Vis, fluorescence intensity, phenol content, and viscosity measurements. An insoluble polymer was obtained after 45 min, which was attributed to coupling reactions triggered by phenoxyl radicals within the tannins mixture. The polymer showed a marked increase in thermal stability compared with the precursor pine bark extract, with a total mass loss of less than 12% at temperatures up to 500°C, suggesting potential practical applications in flame retardant materials. Additionally, the polymer showed an 85% DPPH activity and a 60% attenuation of singlet oxygen release upon light irradiation, which supports antioxidant and photoprotective properties for the prepared material. To the best of our knowledge, this is the first report to describe the formation of an insoluble polymer by direct enzymatic reaction of an aqueous tannin extract. In this case, soluble tannins are the sole reactants used to produce a promising versatile material for forest waste valorization. [ABSTRACT FROM AUTHOR]

Development of a simple and efficient catalytic system is significant for the synthesis of 1,3-diynes in organic synthesis. Herein, an acidic mesoporous ZSM-5-supported Pd catalyst (Pd@MZSM-5) was able to transform terminal alkynes into 1,3-diynes without any additive under an oxygen atmosphere. The Brønsted acid sites in the Pd@MZSM-5 catalyst could promote the adsorption of alkynes through the interaction of the CRC bond with the hydroxyl group, which benefits the active Pd2+ species bonding with the CRC bond to form the alkynyl-palladium(II) complex. This complex underwent a reductive elimination process to form the 1,3-diyne product. [ABSTRACT FROM AUTHOR]

This article discusses the use of aromatic amine catalysts in a specific chemical reaction. The researchers conducted experiments using different catalysts and found that aryl amines were more effective than alkyl amines. They also discovered that a commercially available proton sponge showed promise as a catalyst. The article explores the catalytic activity of a specific catalyst called cat14 and compares it to other catalysts. While cat14 showed promising results, the study concludes that another scaffold called phenotellurazine performed better in the reactions. Further research is being done to improve the phenotellurazine scaffold and other catalysts. [Extracted from the article]

The incorporation of calcium into the zircon-type lattice of Ce1−xCaxVO4 (x = 0.2–0.4), stable at atmospheric oxygen pressure, leads to a modest decrease in the unit cell volume and electrical conductivity, predominantly electronic. The average linear thermal expansion coefficients (TECs) of vanadate ceramics in air vary in the range (6.6–9.9) × 10−6 K−1 at 393–1123 K, increasing with temperature and x. On reduction in hydrogen, zircon-type Ce1−xCaxVO4 undergoes phase transformation into perovskite-like Ce1−xCaxVO3. This transition is accompanied by a 32% crystal lattice contraction and a drastic increase in the conductivity, up to 120 S/cm at 1123 K for Ce0.6Ca0.4VO3. The average TECs of reduced metavanadates, (9.7–12.7) × 10−6 K−1 at 393–1123 K, are compatible with those of solid oxide electrolytes. As for the variations of electronic resistivity, the polarization resistance of porous Ce1−xCaxVO3 electrodes in reducing atmospheres decreases with calcium additions. The electrochemical activity of Ce1−xCaxVO3 in contact with zirconia-based electrolyte, and protective ceria interlayer is higher for H2O electrolysis with respect to H2 oxidation. [ABSTRACT FROM AUTHOR]

This work shows the synthesis, characterization and evaluation of dense-ceramic membranes made of Ce 0.85 Gd 0.15 O 2-δ -LaNiO 3 (CG-LN) composites, where the fluorite-perovskite ratio (CG:LN) was varied as follows: 75:25, 80:20 and 85:15 wt.%. Supports were initially characterized by XRD, SEM and electrical conductivity (using vacuum and oxygen atmospheres), to determine the composition, microstructural and ionic-electronic conductivity properties. Later, supports were infiltrated with an eutectic carbonates mixture, producing the corresponding dense dual-phase membranes, in which CO 2 permeation tests were conducted. Here, CO 2 permeation experiments were performed from 900 to 700°C, in the presence and absence of oxygen (flowed in the sweep membrane side). Results showed that these composites possess high CO 2 permeation properties, where the O 2 addition significantly improves the ionic conduction on the sweep membrane side. Specifically, the GC80-LN20 composition presented the best results due to the following physicochemical characteristics: high electronic and ionic conductivity, appropriate porosity, interconnected porous channels, as well as thermal and chemical stabilities between the composite support and carbonate phases. [ABSTRACT FROM AUTHOR]

The effect of the thickness of thin protective In-Sn-O coatings, deposited on quartz glass by magnetron sputtering at various partial pressures in an argon and oxygen atmosphere, on their impact resistance and light transmission is studied. A correlation is revealed between the light transmittance in the ultraviolet (UV) region, the surface density of craters formed by hypervelocity bombardment with iron microparticles, and the sizes of the craters on the coating surfaces. The results of bombarding the In-Sn-O/quartz glass targets with a flow of microparticles using a light gas gun show that the UV transmittance of the coatings with different thicknesses (~4 and ~6 μm) increases by up to 12%, while for the uncoated KV quartz glass it decreases from 92% to 54% after bombardment. The number of craters forming on the coating surfaces depends on their thickness: with an increase in the In-Sn-O coating thickness to ~6 μm, the surface area occupied by the craters decreases, while the optical transmittance spectrum of the coatings remains unchanged. [ABSTRACT FROM AUTHOR]