In the electrochemical CO2 reduction reaction (CO2RR), Cu has been spotlighted as the only electro-catalyst that can produce multi-carbon molecules, but the mechanism of the selective C2+ production ...reaction remains elusive. Here, we directly monitored CO2RR intermediates by employing time-resolved attenuated total reflection-surface enhanced infrared absorption spectroscopy (ATR-SEIRAS), with particular attention to the C1 and C2+ pathways beyond the formation of *CO. Electrodeposited Cu and Cu(OH)2-derived Cu were synthesized, and subsequently employed as a C1 and C2+ activating catalyst and C2+ activating catalyst, respectively. For the first time, a kinetically linked dimer intermediate (*OCCO) was observed and identified as the C2+ path triggering intermediate. The ATR-SEIRAS results suggest that C–C coupling occurs exclusively by CO dimerization toward *OCCO, without the participation of *CHO, which is an intermediate for CH4 production. In the real-time measurements, CO dimerization occurred concurrently with CO adsorption (∼5 s), while proton-coupled reduction toward *CHO has slower kinetics (∼30 s). We demonstrated that the sites showing a high vibrational frequency of *CO on the fragmented Cu surface are the potential active sites for the fast dimerization of CO. This work provides mechanistic insights into the CO2RR pathways and enables the design of efficient C2+-producing catalysts.
Oxygen–Cu (O–Cu) combination catalysts have recently achieved highly improved selectivity for ethylene production from the electrochemical CO2 reduction reaction (CO2RR). In this study, we developed ...anodized copper (AN-Cu) Cu(OH)2 catalysts by a simple electrochemical synthesis method and achieved ∼40% Faradaic efficiency for ethylene production, and high stability over 40 h. Notably, the initial reduction conditions applied to AN-Cu were critical to achieving selective and stable ethylene production activity from the CO2RR, as the initial reduction condition affects the structures and chemical states, crucial for highly selective and stable ethylene production over methane. A highly negative reduction potential produced a catalyst maintaining long-term stability for the selective production of ethylene over methane, and a small amount of Cu(OH)2 was still observed on the catalyst surface. Meanwhile, when a mild reduction condition was applied to the AN-Cu, the Cu(OH)2 crystal structure and mixed states disappeared on the catalyst, becoming more favorable to methane production after few hours. These results show the selectivity of ethylene to methane in O–Cu combination catalysts is influenced by the electrochemical reduction environment related to the mixed valences. This will provide new strategies to improve durability of O–Cu combination catalysts for C–C coupling products from electrochemical CO2 conversion.
Electrochemical reduction of carbon dioxide (CO2RR) product distribution has been identified to be dependent on various surface factors, including the Cu facet, morphology, chemical states, doping, ...etc., which can alter the binding strength of key intermediates such as *CO and *OCCO during reduction. Therefore, in‐depth knowledge of the Cu catalyst surface and identification of the active species under reaction conditions aid in designing efficient Cu‐based electrocatalysts. This progress report categorizes various Cu‐based electrocatalysts into four main groups, namely metallic Cu, Cu alloys, Cu compounds (Cu + non‐metal), and supported Cu‐based catalysts (Cu supported by carbon, metal oxides, or polymers). The detailed mechanisms for the selective CO2RR are presented, followed by recent relevant developments on the synthetic procedures for preparing Cu and Cu‐based nanoparticles. Herein, the potential link between the Cu surface and CO2RR performance is highlighted, especially in terms of the chemical states, but other significant factors such as defective sites and roughened morphology of catalysts are equally considered during the discussion of current studies of CO2RR with Cu‐based electrocatalysts to fully understand the origin of the significant enhancement toward C2 formation. This report concludes by providing suggestions for future designs of highly selective and stable Cu‐based electrocatalysts for CO2RR.
Recent theoretical studies report that the changes in the Cu surface states during the modification of Cu‐based electrocatalysts, from metallic Cu to copper oxides or vice versa, can determine the identity of carbon products. Thus, the link between changes on Cu surface and the catalytic performance for the CC coupling reaction is investigated.
In this study, we demonstrate that the initial morphology of nanoparticles can be transformed into small fragmented nanoparticles, which were densely contacted to each other, during electrochemical ...CO2 reduction reaction (CO2RR). Cu-based nanoparticles were directly grown on a carbon support by using cysteamine immobilization agent, and the synthesized nanoparticle catalyst showed increasing activity during initial CO2RR, doubling Faradaic efficiency of C2H4 production from 27% to 57.3%. The increased C2H4 production activity was related to the morphological transformation over reaction time. Twenty nm cubic Cu2O crystalline particles gradually experienced in situ electrochemical fragmentation into 2–4 nm small particles under the negative potential, and the fragmentation was found to be initiated from the surface of the nanocrystal. Compared to Cu@CuO nanoparticle/C or bulk Cu foil, the fragmented Cu-based NP/C catalyst achieved enhanced C2+ production selectivity, accounting 87% of the total CO2RR products, and suppressed H2 production. In-situ X-ray absorption near edge structure studies showed metallic Cu0 state was observed under CO2RR, but the fragmented nanoparticles were more readily reoxidized at open circuit potential inside of the electrolyte, allowing labile Cu states. The unique morphology, small nanoparticles stacked upon on another, is proposed to promote C–C coupling reaction selectivity from CO2RR by suppressing HER.
A high-resolution X-ray microscope was used to quantitate the internal morphological characteristics of 3D-printed, basalt-fiber-reinforced PLA composites. 3D-printed composites have microstructures ...and mechanical properties that are distinct from those of conventional mold-pressed composites. One such distinction lies in the presence of voids, which form naturally during 3D printing. All of the composite components, including the fiber, the matrix, and the aforementioned voids were oriented parallel to the printing direction. The mechanical properties of the final composites were also greatly impacted by their microstructural characteristics, including fiber length, fiber orientation, and the presence of voids. It was also confirmed that the voids generated during the 3D printing process can be classified into two types (inter- and inner-filament voids), whose shapes, sizes, and distributions are completely different from each other, and that they clearly have a decisive influence on the remarkable differences in the strength of the composites.
Autophagy is a critical regulator of cellular homeostasis, dysregulation of which is associated with diverse diseases. Here we show therapeutic effects of a novel autophagy enhancer identified by ...high-throughput screening of a chemical library against metabolic syndrome. An autophagy enhancer increases LC3-I to LC3-II conversion without mTOR inhibition. MSL, an autophagy enhancer, activates calcineurin, and induces dephosphorylation/nuclear translocation of transcription factor EB (TFEB), a master regulator of lysosomal biogenesis and autophagy gene expression. MSL accelerates intracellular lipid clearance, which is reversed by lalistat 2 or Tfeb knockout. Its administration improves the metabolic profile of ob/ob mice and ameliorates inflammasome activation. A chemically modified MSL with increased microsomal stability improves the glucose profile not only of ob/ob mice but also of mice with diet-induced obesity. Our data indicate that our novel autophagy enhancer could be a new drug candidate for diabetes or metabolic syndrome with lipid overload.
Scope
The study aims to determine whether Lactobacillus plantarum C29‐fermented defatted soybean (FDS, DW2009) can attenuate memory impairment in 5XFAD transgenic (Tg) mice.
Methods and results
Oral ...administration of FDS or C29 increases cognitive function in Tg mice in passive avoidance, Y‐maze, novel object recognition, and Morris water maze tasks. FDS or C29 treatment significantly suppresses amyloid‐β, β/γ‐secretases, caspase‐3 expression, and NF‐κB activation, and activates microglia and apoptotic neuron cell populations, and increases BDNF expression in the brain. FDS or C29 treatment suppresses blood and fecal lipopolysaccharide levels and Enterobacteriaceae population and increases lactobacilli/bifidobacteria populations.
Conclusion
FDS and C29 alleviates the decrease in cognitive function and inhibited amyloid‐β expression in Tg mice by regulating microglia activation and gut microbiota composition.
A major hallmark of Alzheimer's disease is cognitive impairment and amyloid‐β (Aβ) deposits in brain. In the present study, it is found that Lactobacillus plantarum C29‐fermented defatted soybean (FDS) and C29 alleviated cognitive function and inhibited amyloid‐β expression in 5XFAD transgenic mice by regulating microglia activation and gut microbiota composition.
Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with ...conventional porous silicon materials. These porous nanowires also retain the crystallographic orientation of the wafer from which they are etched. Electron microscopy and diffraction confirm their single-crystallinity and reveal the silicon surrounding the pores is as thin as several nanometers. Confocal fluorescence microscopy showed that the photoluminescence (PL) of these arrays emanate from the nanowires themselves, and their PL spectrum suggests that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices.
Several studies have shown that depression increases the risk of metabolic syndrome (MetS), which is often exacerbated by the fact that both exist concurrently. People with depression are more likely ...to have unhealthy eating habits, which can eventually trigger the development of MetS. This study was to investigate whether diet quality modifies the association between depression and MetS in a total of 13,539 Korean adults aged 19 to 80 from 2014, 2016 and 2018 Korean National Health and Nutrition Examination Surveys. Depression was assessed by the Patient Health Questionnaire-9 (PHQ-9) and subjects were divided into subgroups according to the PHQ-9 scores: normal (<5), mild (5-9), and moderate-to-severe (≥10) groups. Diet quality was measured by the Korean Healthy Eating Index (KHEI). A complex sample multiple logistic regression stratified by tertiles of KHEI scores was used to explore whether diet quality modifies an association between depression severity and metabolic syndrome. Depression severity was positively associated with the risk of MetS (
trend = 0.006) after adjustment for potential confounders. Only the lowest diet quality, moderately-to-severely depressed group, showed a higher risk of MetS (OR: 1.72, 95% CI: 1.24-2.40) compared to the normal group. Our results suggest that healthy diet quality could offset the positive relationship between depression and MetS in the general Korean adult population. Encouraging a healthy diet regime can improve not only physical health but also the mental state of the general public.
This study evaluated the effect of barium titanate (BT) on the dielectricity, radiopacity, and biological properties of tricalcium silicate (C3S). C3S/BT samples were prepared with varying ...proportions of BT (0, 20, 40, and 60 wt%; referred to as BT00, BT20, BT40, and BT60, respectively). Dielectric constant and radiopacity were measured. Cytocompatibility was evaluated on human dental pulp cells. After surgical procedures on rat mandible, immunohistochemistry and Masson’s trichrome staining were performed. The dielectric constant increased with higher proportions of BT (p<0.05). BT40 and BT60 satisfied the clinical guideline of radiopacity. There were no significant differences among groups in the cytocompatibility tests (p>0.05). New bone was observed well, along with the expressions of the dentin matrix protein 1 (DMP1), osteocalcin (OC), and osteonectin (ON) in BT40 and BT60. Conclusively, the contents of 40–60 wt% of BT in C3S provided proper radiopacity, favorable cytocompatibility, and beneficial effect on bone regeneration.
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