High entropy perovskite oxides (HEPOs) have been proposed to serve as improved cathode materials for solid oxide fuel cells (SOFCs); however, the larger compositional design space introduced by HEPOs ...urges for a better understanding of the correlation among the composition, phase stability and resulting properties of HEPO cathodes. In this work, a series of LaMnO 3 based HEPOs (HEALMOs) were designed systematically to investigate the effect of the A site high entropy composition on the structure and thermochemical/electrical properties of HEALMO materials. The results show that the high entropy effect manifests itself on top of the conventional doping effect. First of all, neither the Goldschmidt tolerance factor nor the cation size difference can be used simply to predict the formation ability of single-phase HEALMOs. Meanwhile, HEALMOs may exhibit higher crystallographic symmetry with much higher cation size differences and at Goldschmidt tolerance factor values deviating more largely from 1. Secondly, while high-temperature stability including both resistance to elemental segregation and chemical compatibility with 8YSZ is affected by the A site cation size difference in a similar way to that of conventional perovskite oxides, HEALMOs show much enhanced stability at larger A site cation size differences. Finally, high entropy contributes to the maintenance of electrical conductivity in the high temperature range. The optimum HEALMO with the composition of (La 0.2 Nd 0.2 Sm 0.2 Ca 0.2 Sr 0.2 )MnO 3 exhibits a combination of excellent high-temperature stability and good electrical conductivity, highlighting its great potential as a promising cathode material for SOFCs.
Producing hydrogen fuel through environmentally friendly electrochemical and solar-driven photoelectrochemical (PEC) water splitting is a very promising approach for providing affordable clean ...energy. The scalable and sustainable production of hydrogen demands efficient and robust earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) beyond platinum and other precious-metal catalysts. This review provides an overview of molybdenum disulfide (MoS2) and related compounds as inexpensive alternative electrocatalysts for HER catalysis and PEC water splitting. After a background introduction, we discuss the important approaches to improving the intrinsic catalytic activity and overall catalytic performance of MoS2. We further review the key developments in combining MoS2 with semiconductors for integrated PEC systems for direct solar-to-fuel conversion and provide insights on how to design efficient solar-driven water-splitting systems. Our perspectives on the key challenges and future directions for development of earth-abundant HER electrocatalysts and PEC water splitting are also discussed.
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Generating hydrogen fuel through electrochemical and solar-driven photoelectrochemical (PEC) water splitting is a very promising approach to providing affordable clean energy, reducing our reliance on fossil fuels, and mitigating the impact of climate change. The sustainable production of hydrogen demands efficient and robust earth-abundant catalysts that are not based on platinum and other precious metals for the hydrogen evolution reaction (HER).
This review focuses on molybdenum disulfide (MoS2) and related compounds as inexpensive alternatives for HER catalysis and PEC water splitting. We discuss key approaches to improving the intrinsic catalytic activity and overall catalytic performance and the developments in combining MoS2 with semiconductors to realize solar-to-fuel conversion. We also discuss how to design efficient PEC water-splitting systems, as well as our perspectives on the key challenges and future directions for developing earth-abundant HER electrocatalysts and PEC water splitting.
This review provides an overview of molybdenum disulfide (MoS2) and related compounds as inexpensive alternatives for hydrogen evolution reaction electrocatalysis and solar-driven photoelectrochemical water splitting toward the goals of producing hydrogen fuel to provide affordable clean energy. Important approaches to improving the intrinsic catalytic activity, developments in combining MoS2 with semiconductors to design efficient water-splitting systems, and perspectives on the challenges and future directions are discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Oxidative stress in depression is a prime cause of neurotransmitter metabolism dysfunction in the brain. Acetylcholinesterase (AChE), a key hydrolase in the cholinergic system, directly determines ...the degradation of neurotransmitters. However, due to the complexity of the brain and lack of appropriate in situ imaging tools, the mechanism underlying the changes in AChE activity in depression remains unclear. Hence, we generated a two-photon fluorescence probe (MCYN) for real-time visualization of AChE with excellent sensitivity and selectivity. AChE can specifically recognize and cleave the carbamic acid ester bond in MCYN, and MCYN emits bright fluorescence at 560 nm by two-photon excitation at 800 nm. By utilizing MCYN to monitor AChE, we discovered a significant increase in AChE activity in the brains of mice with depression phenotypes. Notably, with the assistance of a two-photon fluorescence imaging probe of the superoxide anion radical (O2 •–), in vivo visualization for the first time revealed the positive correlation between AChE and O2 •– levels associated with depressive behaviors. This finding suggests that oxidative stress may induce AChE overactivation, leading to depression-related behaviors. This work provides a new and rewarding perspective to elucidate the role of oxidative stress regulating AChE in the pathology of depression.
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IJS, KILJ, NUK, PNG, UL, UM
α-Tertiary amides are of great importance for medicinal chemistry. However, they are often challenging to access through conventional methods due to reactivity and chemoselectivity issues. Here, we ...report a single-step approach towards such amides via cobalt-catalyzed intermolecular oxidative hydroamidation of unactivated alkenes, using nitriles of either solvent- or reagent-quantities. This protocol is selective for terminal alkenes over groups that rapidly react under known carbocation amidation conditions such as tertiary alcohols, electron-rich alkenes, ketals, weak C-H bonds, and carboxylic acids. Straightforward access to a diverse array of hindered amides is demonstrated, including a rapid synthesis of an aminoadamantane-derived pharmaceutical intermediate.
MicroRNAs have been implicated in diverse physiological and pathological processes. We previously reported that aberrant microRNA‐124 (miR‐124)/non‐receptor–type protein phosphatase 1 (PTPN1) ...signaling plays an important role in the synaptic disorders associated with Alzheimer's disease (AD). In this study, we further investigated the potential role of miR‐124/PTPN1 in the tau pathology of AD. We first treated the mice with intra‐hippocampal stereotactic injections. Then, we used quantitative real‐time reverse transcription PCR (qRT‐PCR) to detect the expression of microRNAs. Western blotting was used to measure the level of PTPN1, the level of tau protein, the phosphorylation of tau at AD‐related sites, and alterations in the activity of glycogen synthase kinase 3β (GSK‐3β) and protein phosphatase 2 (PP2A). Immunohistochemistry was also used to detect changes in tau phosphorylation levels at AD‐related sites and somadendritic aggregation. Soluble and insoluble tau protein was separated by 70% formic acid (FA) extraction to examine tau solubility. Finally, behavioral experiments (including the Morris water maze, fear conditioning, and elevated plus maze) were performed to examine learning and memory ability and emotion‐related behavior. We found that artificially replicating the abnormalities in miR‐124/PTPN1 signaling induced AD‐like tau pathology in the hippocampus of wild‐type mice, including hyperphosphorylation at multiple sites, insolubility and somadendritic aggregation, as well as learning/memory deficits. We also found that disruption of miR‐124/PTPN1 signaling was caused by the loss of RE1‐silencing transcription factor protein, which can be initiated by Aβ insults or oxidative stress, as observed in the brains of P301S mice. Correcting the deregulation of miR‐124/PTPN1 signaling rescued the tau pathology and learning/memory impairments in the P301S mice. We also found that miR‐124/PTPN1 abnormalities induced activation of glycogen synthase kinase 3 (GSK‐3) and inactivation of protein phosphatase 2A (PP2A) by promoting tyrosine phosphorylation, implicating an imbalance in tau kinase/phosphatase. Thus, targeting the miR‐124/PTPN1 signaling pathway is a promising therapeutic strategy for AD.
Disruption of miRNA signals had been implicated in Alzheimer's disease (AD). We previously reported that aberrant miR‐124/PTPN1 signaling induces the synaptic disorders in AD. In this study, we further investigated the potential role of miR‐124/PTPN1 in the tau pathology of AD. We found that artificially replicated disturbance of miR‐124/PTPN1 results in the tau pathology while correcting this abnormality rescued the tau pathology and learning/memory impairments in the P301S mice. Our study extends the critical role of miR‐124/PTPN1 in the pathogenesis and provides the potential therapeutic target for AD.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The development of efficient and robust earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) is an ongoing challenge. We report metallic cobalt pyrite (cobalt disulfide, CoS2) as ...one such high-activity candidate material and demonstrate that its specific morphologyfilm, microwire, or nanowire, made available through controlled synthesisplays a crucial role in determining its overall catalytic efficacy. The increase in effective electrode surface area that accompanies CoS2 micro- and nanostructuring substantially boosts its HER catalytic performance, with CoS2 nanowire electrodes achieving geometric current densities of −10 mA cm–2 at overpotentials as low as −145 mV vs the reversible hydrogen electrode. Moreover, micro- and nanostructuring of the CoS2 material has the synergistic effect of increasing its operational stability, cyclability, and maximum achievable rate of hydrogen generation by promoting the release of evolved gas bubbles from the electrode surface. The benefits of catalyst micro- and nanostructuring are further demonstrated by the increased electrocatalytic activity of CoS2 nanowire electrodes over planar film electrodes toward polysulfide and triiodide reduction, which suggests a straightforward way to improve the performance of quantum dot- and dye-sensitized solar cells, respectively. Extension of this micro- and nanostructuring strategy to other earth-abundant materials could similarly enable inexpensive electrocatalysts that lack the high intrinsic activity of the noble metals.
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Uniaxial compression tests were performed to study the influence of temperature on the physical and mechanical behaviour of granite. Then water flow experiments were conducted on the fractured ...granite specimens that were thermally treated at varying confining pressure. There is a statistical correlation between P-wave velocity and mechanical properties such as uniaxial compression strength and Young's modulus. When the temperature is greater than 600 °C, the mechanical parameters of granite decrease rapidly. As the temperature increases, the changes in the permeability are divided into three significant stages, namely slight decrease, rapid increase and finally slowed growth. As the confining pressure increases, internal pores and micro-cracks are closed, so that the permeability decreases continuously. However, with a greater confining pressure, the change in pore and fracture structure tends to be stable, and the slope of the permeability curve decreases gradually with the increase of confining pressure.
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•There is a statistical correlation between P-wave velocity and mechanical properties.•The changes in the permeability are divided into three significant stages.•The slope of permeability curve decreases gradually as confining pressure increases.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Many materials have been explored as potential hydrogen evolution reaction (HER) electrocatalysts to generate clean hydrogen fuel via water electrolysis, but none so far compete with the highly ...efficient and stable (but cost prohibitive) noble metals. Similarly, noble metals often excel as electrocatalytic counter electrode materials in regenerative liquid-junction photoelectrochemical solar cells, such as quantum dot-sensitized solar cells (QDSSCs) that employ the sulfide/polysulfide redox electrolyte as the hole mediator. Here, we systematically investigate thin films of the earth-abundant pyrite-phase transition metal disulfides (FeS2, CoS2, NiS2, and their alloys) as promising alternative electrocatalysts for both the HER and polysulfide reduction. Their electrocatalytic activity toward the HER is correlated to their composition and morphology. The emergent trends in their performance suggest that cobalt plays an important role in facilitating the HER, with CoS2 exhibiting highest overall performance. Additionally, we demonstrate the high activity of the transition metal pyrites toward polysulfide reduction and highlight the particularly high intrinsic activity of NiS2, which could enable improved QDSSC performance. Furthermore, structural disorder introduced by alloying different transition metal pyrites could increase their areal density of active sites for catalysis, leading to enhanced performance.
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IJS, KILJ, NUK, PNG, UL, UM
Glyphosate is a high-efficiency, low-toxicity, broad-spectrum herbicide. The residues of glyphosate-based herbicides are frequent pollutants in the environment. However, the effects of glyphosate on ...oocyte maturation, as well as its possible mechanisms, remain unclear. The present study revealed that mouse oocytes had reduced rates of germinal vesicle breakdown (GVBD) and first polar body extrusion (PBE) after treatment with 500 μM glyphosate. Reactive oxygen species (ROS) were found in mouse oocytes exposed to glyphosate, as shown by changes in the mRNA expression of related antioxidant enzyme genes (cat, sod2, gpx). After 14 h of exposure to glyphosate, metaphase II (MII) mouse oocytes displayed an abnormal spindle morphology and DNA double-strand breaks (DNA-DSBs). Simultaneously, mitochondria showed an aggregated distribution and decreased membrane potential in mouse oocytes exposed to glyphosate. The protein expression levels of apoptosis factors (Bax, Bcl-2) and the mRNA expression levels of apoptosis-related genes (bax, bcl-2, caspase3) were measured by Western blot and qRT-PCR, respectively. Meanwhile, the expression levels of autophagy-related genes (lc3, atg14, mtor) and proteins (LC3, Atg12) were significantly decreased in the glyphosate treatment group compared with the control group. Collectively, our results indicated that glyphosate exposure could interfere with mouse oocyte maturation by generating oxidative stress and early apoptosis.
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•Glyphosate exposure interferenced the GVBD and PBE in mouse oocytes.•Glyphosate exposure induced ROS and DNA damage in mouse oocytes.•Glyphosate exposure induced abnormal meiotic spindle in mouse oocytes.•Glyphosate exposure changed mitochondrial function in mouse oocytes.•Glyphosate induced early-apoptosis and autophagy in mouse oocytes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The adsorption of atmospheric dinitrogen (N2) on transition metal sites is an important topic in chemistry, which is regarded as the prerequisite for the activation of robust N≡N bonds in biological ...and industrial fields. Metal hydride bonds play an important part in the adsorption of N2, while the role of hydrogen has not been comprehensively studied. Herein, we report the N2 adsorption on the well-defined Y2C4H0,1− cluster anions under mild conditions by using mass spectrometry and density functional theory calculations. The mass spectrometry results reveal that the reactivity of N2 adsorption on Y2C4H− is 50 times higher than that on Y2C4− clusters. Further analysis reveals the important role of the H atom: (1) the presence of the H atom modifies the charge distribution of the Y2C4H− anion; (2) the approach of N2 to Y2C4H− is more favorable kinetically compared to that to Y2C4−; and (3) a natural charge analysis shows that two Y atoms and one Y atom are the major electron donors in the Y2C4− and Y2C4H− anion clusters, respectively. This work provides new clues to the rational design of TM-based catalysts by efficiently doping hydrogen atoms to modulate the reactivity towards N2.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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