Effects of the Crystalline Properties of Hollow Ceria Nanostructures on a CuO-CeO2 Catalyst in CO Oxidation

The development of an efficient and economic catalyst with high catalytic performance is always challenging. In this study, we report the synthesis of hollow CeO₂ nanostructures and the crystallinity control of a CeO₂ layer used as a support material for a CuO-CeO₂ catalyst in CO oxidation. The hollow CeO₂ nanostructures were synthesized using a simple hydrothermal method. The crystallinity of the hollow CeO₂ shell layer was controlled through thermal treatment at various temperatures. The crystallinity of hollow CeO₂ was enhanced by increasing the calcination temperature, but both porosity and surface area decreased, showing an opposite trend to that of crystallinity. The crystallinity of hollow CeO₂ significantly influenced both the characteristics and the catalytic performance of the corresponding hollow CuO-CeO₂ (H-Cu-CeO₂) catalysts. The degree of oxygen vacancy significantly decreased with the calcination temperature. H-Cu-CeO₂ (HT), which presented the lowest CeO₂ crystallinity, not only had a high degree of oxygen vacancy but also showed well-dispersed CuO species, while H-Cu-CeO₂ (800), with well-developed crystallinity, showed low CuO dispersion. The H-Cu-CeO₂ (HT) catalyst exhibited significantly enhanced catalytic activity and stability. In this study, we systemically analyzed the characteristics and catalyst performance of hollow CeO₂ samples and the corresponding hollow CuO-CeO₂ catalysts.     

Mitochondrial Ca2+ flux and respiratory enzyme activity decline are early events in cardiomyocyte response to H2O2

Oxidative stress is involved in mitochondrial apoptosis, and plays a critical role in ischemic heart disease and cardiac failure. Exposure of cardiomyocytes to H₂O₂ leads to oxidative stress and mitochondrial dysfunction. In this study, we investigated the temporal order of mitochondrial-related events in the neonatal rat cardiomyocyte response to H₂O₂ treatment. At times ranging from 10 to 90 min after H₂O₂ treatment, levels were determined for respiratory complexes I, II, IV and V, and citrate synthase activities, mitochondrial Ca²⁺ flux, intracellular oxidation, mitochondrial membrane potential and apoptotic progression. Complexes II and IV activity levels were significantly reduced within 20 min of H₂O₂ exposure while complexes I and V, and citrate synthase were unaffected. Mitochondrial membrane potential declined after 20 and 60 min of H₂O₂ exposure while intracellular oxidation, declining complex I activity and apoptotic progression were detectable only after 60 min. Measurement of mitochondrial Ca²⁺ ([Ca²⁺]_m) using rhodamine 2 detected an early accumulation of [Ca²⁺]_m occurring between 5 and 10 min. Pretreatment of cardiomyocytes with either ruthenium red or cyclosporin A abrogated the H₂O₂-induced decline in complexes II and IV activities, indicating that [Ca²⁺]_m flux and onset of mitochondrial permeability transition pore opening likely precede the observed early enzymatic decline. Our findings suggest that [Ca²⁺]_m flux represents an early pivotal event in H₂O₂-induced cardiomyocyte damage, preceding and presumably leading to reduced mitochondrial respiratory activity levels followed by accumulation of intracellular oxidation, mitochondrial membrane depolarization and apoptotic progression concomitant with declining complex I activity.     

Machine learning–based inverse design for electrochemically controlled microscopic gradients of O2 and H2O2

A fundamental understanding of extracellular microenvironments of O₂ and reactive oxygen species (ROS) such as H₂O₂, ubiquitous in microbiology, demands high-throughput methods of mimicking, controlling, and perturbing gradients of O₂ and H₂O₂ at microscopic scale with high spatiotemporal precision. However, there is a paucity of high-throughput strategies of microenvironment design, and it remains challenging to achieve O₂ and H₂O₂ heterogeneities with microbiologically desirable spatiotemporal resolutions. Here, we report the inverse design, based on machine learning (ML), of electrochemically generated microscopic O₂ and H₂O₂ profiles relevant for microbiology. Microwire arrays with suitably designed electrochemical catalysts enable the independent control of O₂ and H₂O₂ profiles with spatial resolution of ∼10¹ μm and temporal resolution of ∼10° s. Neural networks aided by data augmentation inversely design the experimental conditions needed for targeted O₂ and H₂O₂ microenvironments while being two orders of magnitude faster than experimental explorations. Interfacing ML-based inverse design with electrochemically controlled concentration heterogeneity creates a viable fast-response platform toward better understanding the extracellular space with desirable spatiotemporal control.

Ubiquitous spatiotemporal heterogeneity of natural environments fosters the diverse and fascinating biology that our world embraces, and motivates researchers to mimic natural environments with high spatiotemporal resolution (1–5). Given their close relevance in biochemical metabolisms, dioxygen (O₂) and hydrogen peroxide (H₂O₂) as a surrogate of reactive oxygen species (ROS) are two ubiquitous biologically relevant species in extracellular medium (1, 6). Their extracellular spatial and temporal distributions, particularly at the microscopic scale ranging from 1 μm to 100 μm (7–11), are critical for signal transduction, protein expression, biochemical redox balance, and regulation for cellular metabolism with extensive ecological, environmental, and biomedical implications (Fig. 1A) (1, 3, 8–13). A programmable creation of the spatiotemporal concentration profiles of O₂ and H₂O₂ offers the freedom to mimic, control, and perturb the microenvironments of O₂ and H₂O₂ and hence advance our understanding in microbiology.Open in a separate windowFig. 1.AI-based inverse design of electrochemically generated O₂ and H₂O₂ heterogeneities. (A) The ubiquitous spatiotemporal heterogeneities of O₂ and H₂O₂ in microbiology and the challenges posed in this research topic. (B) The combination of electrochemistry and ML-based inverse design offers a viable approach to mimicking and controlling the heterogeneities of O₂ and H₂O₂ in microbiology. O, oxidant; R, reductant; E_appl (t), the time-dependent electrochemical voltages applied on electrodes. (C) The design of the electrochemically active microwire array electrodes for the generation of O₂ and H₂O₂ gradients; 4e⁻ ORR & 2e⁻ ORR, four-electron and two-electron oxygen reduction reaction into H₂O and H₂O₂, respectively. (D and E) The 45°-tilting images of SEM for the representative microwire arrays used for the training of the ML model (D) and the ones inversely designed for targeted O₂ and H₂O₂ gradients (E); k = (P, D, L), the morphological vector that includes the P, D, and L of the synthesized wire arrays in units of micrometers. (Scale bars, 20 μm.)Despite recent progress (14–18), there remain major technical challenges, particularly in the achievable spatiotemporal resolution and high-throughput design of concentration profiles to suit a plethora of scenarios in microbiology. Approaches based on microfluidics and hydrogels have been able to achieve concentration gradients of O₂ and H₂O₂ through the provision of either O₂/H₂O₂ source (14, 19–21), O₂/H₂O₂ scavenging agents (15, 22, 23), or a combination of both (24) across liquid-impermeable barriers such as agar layers or polymeric thin films (25, 26). Yet such approaches, dependent on passive mass transport and diffusion across more than 10² μm, are inherently incapable of achieving spatial features of less than 100 μm and temporal resolution smaller than ∼10¹ s, the prerequisites to investigate microbiology at cluster or single-cell levels (10–12). Moreover, the large variations of extracellular O₂ and H₂O₂ gradients in different microbial systems demand an inverse design strategy, which, with minimal expenditure, quickly programs a desired concentration profile catering to a specific biological scenario (2–5). The current lack of inverse design protocol impedes the adoption of controllable extracellular heterogeneity to mimic and investigate microbial systems that are of environmental, biomedical, and sustainability-related significance.We envision that the integration of electrochemically generated concentration gradients with inverse design based on machine learning (ML) will address the aforementioned challenges (Fig. 1B). Electrochemistry offers a venue for transducing electric signals into microscopic concentration profiles within ∼10⁰ μm to ∼10² μm away from electrodes’ surface, following the specific electrode reaction kinetics and the mass transport governing equations in the liquid phase (27). Proper designs of electrodes’ microscopic spatial arrangement and electrochemical kinetics lead to concentration gradients that are spatiotemporally programmable by time-dependent electric signals of varying voltages (28). Such benefits of electrochemically generated concentration gradients lead us to employ electrochemistry as a tool to spatiotemporally control the concentration profiles in the extracellular medium. In one example, we found that wire arrays electrochemically active toward O₂ reduction create anoxic microenvironment about 20 μm away from the aerobic external bulk environments, modulate the size and extent of O₂ depletion in the anoxic microenvironment by the wire array’s morphology and applied electrochemical potential (E_appl), and hence enable O₂-sensitive rhizobial N₂ fixation in ambient air powered by renewable electricity (29). Moreover, while not reported before as far as we know, electrochemically generated concentration heterogeneity is commensurate with ML-based inverse design (30, 31), thanks to the mathematically well-defined electrochemical processes that can be numerically simulated (32, 33). We recently reported neural networks, trained by numerically simulated data, that explore the influence of electrode geometry on electrochemical N₂ fixation and achieve optimized morphologies of wire array electrodes untenable without such an ML-based strategy (34). An inverse design for the electrochemically generated gradients will quickly program desirable microenvironments of O₂ and ROS with high spatiotemporal resolutions, thanks to the well-reported electrochemical transformation related to O₂ and H₂O₂ with high electrochemical selectivity (35, 36).In this work, we report an inverse design based on neural networks for independent electrochemical creation of O₂ and ROS microscopic gradients that are relevant, and mimic their extracellular heterogeneities in microbial systems. We hypothesize that careful design of electrocatalysis of O₂ reduction reaction (ORR) can either facilitate four-electron ORR on Pt electrocatalyst for a controllable O₂ spatiotemporal profile or promote two-electron ORR on Au electrocatalyst for a programmable generation of H₂O₂ gradient without significantly perturbing the O₂ one, thanks to their concentration differences in biological mediums (∼10⁻¹ μM to ∼10¹ μM for H₂O₂ and ∼10¹ μM to ∼10² μM for O₂) (2, 7–11). Electrochemically active microwire array electrodes as exemplary model systems (Fig. 1C) are experimentally shown to achieve tunable heterogeneities of O₂ and H₂O₂ independently, with spatial resolution of ∼10¹ μm and temporal resolution of ∼10° s, and are suitable as a platform for independently perturbing biologically relevant O₂ and H₂O₂ profiles in microbial systems. We further established and experimentally validated two neural networks that inversely design the wire array electrodes’ morphologies toward targeted microenvironments of O₂ and H₂O₂, respectively, which is at least one order of magnitude faster than trial-and-error numerical simulation and two orders of magnitude faster than experimental explorations. The demonstrated inverse design of electrochemically generated controlled gradients not only demonstrates a full electrochemical control of concentration profiles in an electrode’s proximity but also establishes an approach of spatiotemporally mimicking and perturbing extracellular space guided by artificial intelligence.     

The Influence of SiO2 + SiC + Al (H2PO4)3 Coating on Mechanical and Dielectric Properties for SiCf/MWCNTS/AlPO4 Composites

SiC fiber-reinforced AlPO₄ matrix (SiC_f/MWCNTs/AlPO₄) composites were fabricated using a hot laminating process with multi-walled carbon nanotubes (MWCNTs) as the absorber. A coating prepared from SiO₂ + SiC + Al (H₂PO₄)₃ was applied to the surface of the SiC_f/MWCNTs/AlPO₄ composites prior to an anti-oxidation test at 1273 K in air for 40 h. The anti-oxidation effect was verified by a three-point bending test, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and a dielectric property test. Anti-oxidation mechanism investigations revealed that the coating effectiveness could be attributed to three substances, i.e., SiO₂, SiP₂O_7, and SiO₂ + AlPO₄ solid solution from the reactions of SiC + O₂→SiO₂ + CO, SiO₂ + P₂O₅→SiP₂O₇ and SiO₂ + AlPO₄→solid solution, respectively.     

Comparative Study of the Efficiency of Different Noble Metals Supported on Hydroxyapatite in the Catalytic Lean Methane Oxidation under Realistic Conditions

The combustion of lean methane was studied over palladium, rhodium, platinum, and ruthenium catalysts supported on hydroxyapatite (HAP). The samples were prepared by wetness impregnation and thoroughly characterized by BET, XRD, UV-Vis-NIR spectroscopy, H₂-TPR, OSC, CO chemisorption, and TEM techniques. It was found that the Pd/HAP and Rh/HAP catalysts exhibited a higher activity compared with Pt/HAP and Ru/HAP samples. Thus, the degree of oxidation of the supported metal under the reaction mixture notably influenced its catalytic performance. Although Pd and Rh catalysts could be easily re-oxidized, the re-oxidation of Pt and Ru samples appeared to be a slow process, resulting in small amounts of metal oxide active sites. Feeding water and CO₂ was found to have a negative effect, which was more pronounced in the presence of water, on the activity of Pd and Rh catalysts. However, the inhibiting effect of CO₂ and H₂O decreased by increasing the reaction temperature.     

Eu-Doped Zeolitic Imidazolate Framework-8 Modified Mixed-Crystal TiO2 for Efficient Removal of Basic Fuchsin from Effluent

Zeolitic imidazolate framework-8 (ZIF-8) was doped with a rare-earth metal, Eu, using a solvent synthesis method evenly on the surface of a mixed-crystal TiO₂(Mc-TiO₂) structure in order to produce a core–shell structure composite ZIF-8(Eu)@Mc-TiO₂ adsorption photocatalyst with good adsorption and photocatalytic properties. The characterisation of ZIF-8(Eu)@Mc-TiO₂ was performed via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller analysis (BET) and ultraviolet–visible light differential reflectance spectroscopy (UV-DRs). The results indicated that Eu-doped ZIF-8 was formed evenly on the Mc-TiO₂ surface, a core–shell structure formed and the light-response range was enhanced greatly. The ZIF-8(Eu)@Mc-TiO₂ for basic fuchsin was investigated to validate its photocatalytic performance. The effect of the Eu doping amount, basic fuchsin concentration and photocatalyst dosage on the photocatalytic efficiency were investigated. The results revealed that, when 5%-Eu-doped ZIF-8(Eu)@Mc-TiO₂ (20 mg) was combined with 30 mg/L basic fuchsin (100 mL) under UV irradiation for 1 h, the photocatalytic efficiency could reach 99%. Further, it exhibited a good recycling performance. Thus, it shows certain advantages in its degradation rate and repeatability compared with previously reported materials. All of these factors suggested that, in an aqueous medium, ZIF-8(Eu)@Mc-TiO₂ is an eco-friendly, sustainable and efficient material for the photocatalytic degradation of basic fuchsin.     

Facile Fabrication of ZnO-ZnFe2O4 Hollow Nanostructure by a One-Needle Syringe Electrospinning Method for a High-Selective H2S Gas Sensor

Herein, a facile fabrication process of ZnO-ZnFe₂O₄ hollow nanofibers through one-needle syringe electrospinning and the following calcination process is presented. The various compositions of the ZnO-ZnFe₂O₄ nanofibers are simply created by controlling the metal precursor ratios of Zn and Fe. Moreover, the different diffusion rates of the metal oxides and metal precursors generate a hollow nanostructure during calcination. The hollow structure of the ZnO-ZnFe₂O₄ enables an enlarged surface area and increased gas sensing sites. In addition, the interface of ZnO and ZnFe₂O₄ forms a p-n junction to improve gas response and to lower operation temperature. The optimized ZnO-ZnFe₂O₄ has shown good H₂S gas sensing properties of 84.5 (S = R_a/R_g) at 10 ppm at 250 °C with excellent selectivity. This study shows the good potential of p-n junction ZnO-ZnFe₂O₄ on H₂S detection and affords a promising sensor design for a high-performance gas sensor.     

Unprecedented Use of NHC Gold (I) Complexes as Catalysts for the Selective Oxidation of Ethane to Acetic Acid

The highly efficient eco-friendly synthesis of acetic acid (40% yield) directly from ethane is achieved by the unprecedented use of N-heterocyclic carbene (NHC) and N-heterocyclic oxo-carbene (NHOC) gold(I) catalysts in mild conditions. This is a selective and promising protocol to generate directly acetic acid from ethane, in comparison with the two most used methods: (i) the three-step, capital- and energy-intensive process based on the high-temperature conversion of methane to acetic acid; (ii) the current industrial methanol carbonylation processes, based in iridium and expensive rhodium catalysts. Green metrics determinations highlight the environmental advantages of the new ethane oxidation procedure. Comparison with previous reported published catalysts is performed to highlight the features of this remarkable protocol.     

Erosion and Corrosion Resistance Performance of Laser Metal Deposited High-Entropy Alloy Coatings at Hellisheidi Geothermal Site

Geothermal process equipment and accessories are usually manufactured from low-alloy steels which offer affordability but increase the susceptibility of the materials to corrosion. Applying erosion-corrosion-resistant coatings to these components could represent an economical solution to the problem. In this work, testing of two newly developed laser metal deposited high-entropy alloy (LMD-HEA) coatings—CoCrFeNiMo_0.85 and Al_0.5CoCrFeNi, applied to carbon and stainless steels—was carried out at the Hellisheidi geothermal power plant. Tests in three different geothermal environments were performed at the Hellisheidi site: wellhead test at 194 °C and 14 bar, erosion test at 198 °C and 15 bar, and aerated test at 90 °C and 1 bar. Post-test microstructural characterization was performed via Scanning Eletron Microscope (SEM), Back-Scattered Electrons analysis (BSE), Energy Dispersive X-ray Spectroscopy (EDS), optical microscopy, and optical profilometry while erosion assessment was carried out using an image and chemical analysis. Both the CoCrFeNiMo_0.85 and Al_0.5CoCrFeNi coatings showed manufacturing defects (cracks) and were prone to corrosion damage. Results show that damage in the CoCrFeNiMo_0.85-coated carbon steel can be induced by manufacturing defects in the coating. This was further confirmed by the excellent corrosion resistance performance of the CoCrFeNiMo_0.85 coating deposited onto stainless steel, where no manufacturing cracks were observed.     

Surface Modification of Nanocrystalline LiMn2O4 Using Graphene Oxide Flakes

In this work, a facile, wet chemical synthesis was utilized to achieve a series of lithium manganese oxide (LiMn₂O₄, (LMO) with 1–5%wt. graphene oxide (GO) composites. The average crystallite sizes estimated by the Rietveld method of LMO/GO nanocomposites were in the range of 18–27 nm. The electrochemical performance was studied using CR2013 coin-type cell batteries prepared from pristine LMO material and LMO modified with 5%wt. GO. Synthesized materials were tested as positive electrodes for Li-ion batteries in the voltage range between 3.0 and 4.3 V at room temperature. The specific discharge capacity after 100 cycles for LMO and LMO/5%wt. GO were 84 and 83 mAh g⁻¹, respectively. The LMO material modified with 5%wt. of graphene oxide flakes retained more than 91% of its initial specific capacity, as compared with the 86% of pristine LMO material.     

Influence of Silver as a Catalyst on the Growth of β-Ga2O3 Nanowires on GaAs

A simple and inexpensive thermal oxidation process was performed to synthesize gallium oxide (Ga₂O₃) nanowires using Ag thin film as a catalyst at 800 °C and 1000 °C to understand the effect of the silver catalyst on the nanowire growth. The effect of doping and orientation of the substrates on the growth of Ga₂O₃ nanowires on single-crystal gallium arsenide (GaAs) wafers in atmosphere were investigated. A comprehensive study of the oxide film and nanowire growth was performed using various characterization techniques including XRD, SEM, EDS, focused ion beam (FIB), XPS and STEM. Based on the characterization results, we believe that Ag thin film produces Ag nanoparticles at high temperatures and enhances the reaction between oxygen and gallium, contributing to denser and longer Ga₂O₃ nanowires compared to those grown without silver catalyst. This process can be optimized for large-scale production of high-quality, dense, and long nanowires.     

Use of the O2-Thiosemicarbazide System,for the Leaching of: Gold and Copper from WEEE & Silver Contained in Mining Wastes

Environmental pollution today is a latent risk for humanity, here the need to recycle waste of all kinds. This work is related to the kinetic study of the leaching of gold and copper contained in waste electrical and electronic equipment (WEEE) and silver contained in mining wastes (MW), using the O₂-thiosemicarbazide system. The results obtained show that this non-toxic leaching system is adequate for the leaching of said metals. Reaction orders were found ranging from 0 (Cu), 0.93 (Ag), and 2.01 (Au) for the effect of the reagent concentration and maximum recoveries of 77.7% (Cu), 95.8% (Au), and 60% (Ag) were obtained. Likewise, the activation energies found show that the leaching of WEEE is controlled by diffusion (Cu Ea = 9.06 and Au Ea = 18.25 kJ/Kmol), while the leaching of MW (Ea = 45.55 kJ/Kmol) is controlled by the chemical reaction. For the case of stirring rate, it was found a low effect and only particles from WEEE and MW must be suspended in solution to proceed with the leaching. The pH has effect only at values above 8, and finally, for the case of MW, the O₂ partial pressure has a market effect, going the Ag leaching from 33% at 0.2 atm up to 60% at a 1 atm.     

Boron Oxide Enhancing Stability of MoS2 Anode Materials for Lithium-Ion Batteries

Molybdenum disulfide (MoS₂) is the most well-known transition metal chalcogenide for lithium storage applications because of its simple preparation process, superior optical, physical, and electrical properties, and high stability. However, recent research has shown that bare MoS₂ nanosheet (NS) can be reformed to the bulk structure, and sulfur atoms can be dissolved in electrolytes or form polymeric structures, thereby preventing lithium insertion/desertion and reducing cycling performance. To enhance the electrochemical performance of the MoS₂ NSs, B₂O₃ nanoparticles were decorated on the surface of MoS₂ NSs via a sintering technique. The structure of B₂O₃ decorated MoS₂ changed slightly with the formation of a lattice spacing of ~7.37 Å. The characterization of materials confirmed the formation of B₂O₃ crystals at 30% weight percentage of H₃BO₃ starting materials. In particular, the MoS₂_B3 sample showed a stable capacity of ~500 mAh·g⁻¹ after the first cycle. The cycling test delivered a high reversible specific capacity of ~82% of the second cycle after 100 cycles. Furthermore, the rate performance also showed a remarkable recovery capacity of ~98%. These results suggest that the use of B₂O₃ decorations could be a viable method for improving the stability of anode materials in lithium storage applications.     

Effect of Spraying Power on Oxidation Resistance of MoSi2-ZrB2 Coating for Nb-Si Based Alloy Prepared by Atmospheric Plasma

The MoSi₂-ZrB₂ coatings were prepared on Nb-Si based alloy by atmospheric plasma spraying with the spraying power 40, 43 and 45 kW. The effect of spraying power on the microstructure and oxidation resistance of MoSi₂-ZrB₂ coating at 1250 °C were studied. The results showed that the main constituent phases of coatings were MoSi₂ at all spraying power. The coating became more compact as the spraying power increased. The coating prepared at 45 kW was dense and uniform, which exhibited the best oxidation resistance due to the formation of a dense and uniform glass layer consisting of SiO₂ and ZrSiO₄.     

Effect of Ti3SiC2 and Ti3AlC2 Particles on Microstructure and Wear Resistance of Microarc Oxidation Layers on TC4 Alloy

Microarc oxidation (MAO) layers were prepared using 8g/L Na₂SiO₃ + 6g/L (NaPO₃)₆ + 4g/L Na₂WO₄ electrolyte with the addition of 2g/L Ti₃SiC₂/Ti₃AlC₂ particles under constant-current mode. The roughness, porosity, composition, surface/cross-sectional morphology, and frictional behavior of the prepared MAO layers were characterized by 3D real-color electron microscopy, scanning electron microscopy, X-ray energy spectrometry, X-ray diffractometry, and with a tribo-tester. The results showed that the addition of Ti₃SiC₂ and Ti₃AlC₂ to the electrolyte reduced the porosity of the prepared layers by 9% compared with that of the MAO layer without added particles. The addition of Ti₃SiC₂/Ti₃AlC₂ also reduced the friction coefficient and wear rate of the prepared layers by 35% compared with that of the MAO layer without added particles. It was found that the addition of Ti₃AlC₂ particles to the electrolyte resulted in the lowest porosity and the lowest wear volume.     

Inhibition of apoptosis in acute promyelocytic leukemia cells leads to increases in levels of oxidized protein and LMP2 immunoproteasome

On reaching maturity, animal organs cease to increase in size because of inhibition of cell replication activities. It follows that maintenance of optimal organ function depends on the elimination of oxidatively damaged cells and their replacement with new cells. To examine the effects of oxidative stress and apoptosis on the accumulation of oxidized proteins, we exposed acute promyelocytic leukemia cells to arsenic trioxide (As(2)O(3)) in the presence and absence of a general caspase inhibitor (benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone), which is known to inhibit caspase-induced apoptosis. We confirm that treatment of cells with As(2)O(3) induces apoptosis and leads to the accumulation of oxidized proteins. Furthermore, inhibition of caspase activities prevented As(2)O(3)-induced apoptosis and led to a substantial increase in accumulation of oxidized proteins. Moreover, inhibition of caspase activity in the absence of As(2)O(3) led to elevated levels of the LMP2 immunoproteasome protein. We also show that caspase inhibition leads to increases in the levels of oxidized proteins obtained by treatments with hydrogen peroxide plus ferrous iron. Collectively, these results suggest the possibility that an age-related loss in capacity to carry out apoptosis might contribute to the observed accumulation of oxidized proteins during aging and in age-related diseases.     

Modification of Electrospun CeO2 Nanofibers with CuCrO2 Particles Applied to Hydrogen Harvest from Steam Reforming of Methanol

Hydrogen is the alternative renewable energy source for addressing the energy crisis, global warming, and climate change. Hydrogen is mostly obtained in the industrial process by steam reforming of natural gas. In the present work, CuCrO₂ particles were attached to the surfaces of electrospun CeO₂ nanofibers to form CeO₂-CuCrO₂ nanofibers. However, the CuCrO₂ particles did not readily adhere to the surfaces of the CeO₂ nanofibers, so a trace amount of SiO₂ was added to the surfaces to make them hydrophilic. After the SiO₂ modification, the CeO₂ nanofibers were immersed in Cu-Cr-O precursor and annealed in a vacuum atmosphere to form CeO₂-CuCrO₂ nanofibers. The CuCrO₂, CeO₂, and CeO₂-CuCrO₂ nanofibers were examined by X-ray diffraction analysis, transmission electron microscopy, field emission scanning electron microscopy, scanning transmission electron microscope, thermogravimetric analysis, and Brunauer–Emmett–Teller studies (BET). The BET surface area of the CeO₂-CuCrO₂ nanofibers was 15.06 m²/g. The CeO₂-CuCrO₂ nanofibers exhibited hydrogen generation rates of up to 1335.16 mL min⁻¹ g-cat⁻¹ at 773 K. Furthermore, the CeO₂-CuCrO₂ nanofibers produced more hydrogen at lower temperatures. The hydrogen generation performance of these CeO₂-CuCrO₂ nanofibers could be of great importance in industry and have an economic impact.     

Oxidation of glucose and fatty acids in normal and in A2-cell rich pancreatic islets isolated from guinea-pigs

Summary Glucose and fatty acid oxidation has been measured in normal guinea-pig islets of Langerhans, and in A₂-cell rich islets from streptozotocin-treated guinea-pigs. The rate of oxidation of these compounds in guinea-pig A₂-cells and B-cells has been estimated. In the B-cells, the oxidation of glucose and octanoic acid responded markedly to changes in the extracellular levels of these substrates. Palmitic acid did not appear to be oxidized by the B-cells. In contrast, the oxidation of octanoic acid and palmitic acid in the A₂-cells was very sensitive to changes in the extracellular fatty acid concentration. The sensitivity of glucose oxidation to changes in the glucose concentration was small by comparison. The high rate of oxidation of fatty acids in the A₂-cells supports the view that the rate of fatty acid metabolism in these cells plays an important role in the regulation of glucagon release.

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Die Oxidation von Glucose und Fettsäuren in normalen und isolierten, mit A₂-Zellen angereicherten Pankreasinseln vom Meerschweinchen

Zusammenfassung An normalen Langerhansschen Inseln vom Meerschweinchen und an mit A₂-Zellen angereicherten Inseln von streptozotozin-behandelten Meerschweinchen wurde die Oxidation von Glucose und Fettsäuren gemessen und die Oxidationsrate in A₂-Zellen und B-Zellen des Meerschweinchens bestimmt. In den B-Zellen hing die Oxidation von Glucose und Octansäure stark von den Änderungen der extracellulären Konzentrationen dieser Substanzen ab. Palmitinsäure schien in den B-Zellen nicht oxidiert zu werden. Dagegen war die Oxidation von Oktansäure und Palmitinsäure in den A₂-Zellen sehr von den Schwankungen der extracellulären Fettsäurekonzentration abhängig. Die Änderung der Glucoseoxidation bei Schwankungen der Glucosekonzentration war im Verhältnis dazu gering. Die hohe Oxidationsrate der Fettsäuren in den A₂-Zellen unterstützt die Theorie, daß der Fettsäuremetabolismus dieser Zellen eine wesentliche Rolle in der Regulierung der Glucose-sekretion spielt.

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Oxydation du glucose et des acides gras dans les îlots pancréatiques normaux et dans les îlots riches en cellules A₂ prélevés sur le cobaye

Résumé L'oxydation du glucose et des acides gras a été mesurée dans les îlots normaux de Langerhans chez le cobaye, ainsi que dans les îlots riches en cellules A₂ du cobaye traité à la streptozotocine. Le taux d'oxydation de ces composés dans les cellules A₂ et les cellules B du cobaye a été estimé. Dans les cellules B, l'oxydation du glucose et de l'acide octanoique a fortement répondu à des changements dans les taux extra-cellulaires de ces substrats. L'acide palmitique ne semble pas avoir été oxydé par les cellules B. Au contraire, l'oxydation de l'acide octanoique et de l'acide palmitique dans les cellules A₂ était très sensible aux changements dans la concentration des acides gras extra-cellulaires. La sensibilité de l'oxydation du glucose envers les changements dans la concentration du glucose était comparativement faible. Le taux élevé de l'oxydation des acides gras dans les cellules A₂ corrobore l'hypothèse que le degré du métabolisme des acides gras dans ces cellules joue un rôle important dans la régulation de la sécrétion du glucagon.

     

Large-scale decontamination of disposable FFP2 and FFP3 respirators by hydrogen peroxide vapour,Finland, April to June 2020

BackgroundThe shortage of FFP2 and FFP3 respirators posed a serious threat to the operation of the healthcare system at the onset of the COVID-19 pandemic.AimOur aim was to develop and validate a large-scale facility that uses hydrogen peroxide vapour for the decontamination of used respirators.MethodsA multidisciplinary and multisectoral ad hoc group of experts representing various organisations was assembled to implement the collection and transport of used FFP2 and FFP3 respirators from hospitals covering 86% of the Finnish population. A large-scale decontamination facility using hydrogen peroxide vapour was designed and constructed. Microbiological tests were used to confirm efficacy of hydrogen peroxide vapour decontamination together with a test to assess the effect of decontamination on the filtering efficacy and fit of respirators. Bacterial and fungal growth in stored respirators was determined by standard methods.ResultsLarge-scale hydrogen peroxide vapour decontamination of a range of FFP2 and FFP3 respirator models effectively reduced the recovery of biological indicators: Geobacillus stearothermophilus and Bacillus atrophaeus spores, as well as model virus bacteriophage MS2. The filtering efficacy and facial fit after hydrogen peroxide vapour decontamination were not affected by the process. Microbial growth in the hydrogen peroxide vapour-treated respirators indicated appropriate microbial cleanliness.ConclusionsLarge-scale hydrogen peroxide vapour decontamination was validated. After effective decontamination, no significant changes in the key properties of the respirators were detected. European Union regulations should incorporate a facilitated pathway to allow reuse of appropriately decontaminated respirators in a severe pandemic when unused respirators are not available.     

H(2)O(2)-induced left ventricular dysfunction in isolated working rat hearts is independent of calcium accumulation

Reactive oxygen species (ROS) and intracellular Ca²⁺ overload play key roles in myocardial ischemia-reperfusion (IR) injury but the relationships among ROS, Ca²⁺ overload and LV mechanical dysfunction remain unclear. We tested the hypothesis that H₂O₂ impairs LV function by causing Ca²⁺ overload by increasing late sodium current (I_Na), similar to Sea Anemone Toxin II (ATX-II). Diastolic and systolic Ca²⁺ concentrations (d[Ca²⁺]_i and s[Ca²⁺]_i) were measured by indo-1 fluorescence simultaneously with LV work in isolated working rat hearts. H₂O₂ (100 μM, 30 min) increased d[Ca²⁺]_i and s[Ca²⁺]_i. LV work increased transiently then declined to 32% of baseline before recovering to 70%. ATX-II (12 nM, 30 min) caused greater increases in d[Ca²⁺]_i and s[Ca²⁺]_i. LV work increased transiently before declining gradually to 17%. Ouabain (80 μM) exerted similar effects to ATX-II. Late I_Na inhibitors, lidocaine (10 μM) or R56865 (2 μM), reduced effects of ATX-II on [Ca²⁺]_i and LV function, but did not alter effects of H₂O₂. The antioxidant, N-(2-mercaptopropionyl)glycine (MPG, 1 mM) prevented H₂O₂-induced LV dysfunction, but did not alter [Ca²⁺]_i. Paradoxically, further increases in [Ca²⁺]_i by ATX-II or ouabain, given 10 min after H₂O₂, improved function. The failure of late I_Na inhibitors to prevent H₂O₂-induced LV dysfunction, and the ability of MPG to prevent H₂O₂-induced LV dysfunction independent of changes in [Ca²⁺]_i indicate that impaired contractility is not due to Ca²⁺ overload. The ability of further increases in [Ca²⁺]_i to reverse H₂O₂-induced LV dysfunction suggests that Ca²⁺ desensitization is the predominant mechanism of ROS-induced contractile dysfunction.