One-Pot Etching Pyrolysis to Defect-Rich Carbon Nanosheets to Construct Multiheteroatom-Coordinated Iron Sites for Efficient Oxygen Reduction.

Constructing multiheteroatom coordination structure in carbonaceous substrates demonstrates an effective method to accelerate the oxygen reduction reaction (ORR) of supported single-atom catalyst. Herein, the novel etching route assisted by potassium thiocyanate (KCNS) is developed to convert metal-organic framework to 2D defect-rich porous N,S-co-doped carbon nanosheets for anchoring atomically dispersed iron sites as the high-performance ORR catalysts (Fe-SACs). The well-designed KCNS-assisted etching route can generate spatial confinement template to direct the carbon nanosheet formation, etching condition to form defect-rich structure, and additional sulfur atoms to coordinate iron species. Spectral and microscopy analysis reveals that the iron element in Fe-SACs is highly isolated on carbon nanosheet and anchored by nitrogen and sulfur atoms in unsymmetrical Fe-S1N3 structure. The optimized Fe-SACs with large specific surface area could show remarkable alkaline ORR performances with a high half-wave potential of 0.920 V versus RHE and excellent durability. The rechargeable zinc-air battery assembled with Fe-SACs air electrodes delivers a large power density of 350 mW cm-2 and a stable voltage platform during charge and discharge over more than 1300 h. This work proposes a novel strategy for the preparation of single-atom catalysts with multiheteroatom coordination structure and highly exposed active sites for efficient ORR.

Clinical value of combined serum MMP-2, MMP-9 and TIMP-1 for the prognosis of perianal fistula patients who received minimally invasive surgery.

OBJECTIVE: This study aimed to investigate the clinical value of combined serum matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) for the prognosis of perianal fistula patients. METHODS: Patients diagnosed and treated for perianal fistula by minimally invasive surgery (MIS) were enrolled. The concentrations of serum MMP-2, MMP-9 and TIMP-1 were measured at 24 h after surgery. Different levels of wound secretion, growth of granulation tissue and wound pain were used as criteria to evaluate surgical incision healing. The receiver operating characteristic curve was used to analyze the predicted assessment value. RESULTS: The concentrations of serum MMP-2 and MMP-9 were significantly higher, while the concentrations of serum TIMP-1 at 24 h after surgery were significantly lower in the poor healing group than in the good healing group. It was further found that high levels of serum MMP-2 and MMP-9 were risk factors for poor healing, while high concentrations of serum TIMP-1 at 24 h after surgery were protective factors for poor healing. CONCLUSION: High concentrations of serum MMP-2 and MMP-9 and low concentrations of serum TIMP at 24 h after surgery are risk factors for poor healing in perianal fistula patients who receive MIS, and the combined test has a higher predictive value.

Widely untargeted metabolomic profiling unearths metabolites and pathways involved in leaf senescence and N remobilization in spring-cultivated wheat under different N regimes.

Progression of leaf senescence consists of both degenerative and nutrient recycling processes in crops including wheat. However, the levels of metabolites in flag leaves in spring-cultivated wheat, as well as biosynthetic pathways involved under different nitrogen fertilization regimes, are largely unknown. Therefore, the present study employed a widely untargeted metabolomic profiling strategy to identify metabolites and biosynthetic pathways that could be used in a wheat improvement program aimed at manipulating the rate and onset of senescence by handling spring wheat (Dingxi 38) flag leaves sampled from no-, low-, and high-nitrogen (N) conditions (designated Groups 1, 2, and 3, respectively) across three sampling times: anthesis, grain filling, and end grain filling stages. Through ultrahigh-performance liquid chromatography-tandem mass spectrometry, a total of 826 metabolites comprising 107 flavonoids, 51 phenol lipids, 37 fatty acyls, 37 organooxygen compounds, 31 steroids and steroid derivatives, 18 phenols, and several unknown compounds were detected. Upon the application of the stringent screening criteria for differentially accumulated metabolites (DAMs), 28 and 23 metabolites were differentially accumulated in Group 1_vs_Group 2 and Group 1_vs_Group 3, respectively. From these, 1-O-Caffeoylglucose, Rhoifolin, Eurycomalactone;Ingenol, 4-Methoxyphenyl beta-D-glucopyranoside, and Baldrinal were detected as core conserved DAMs among the three groups with all accumulated higher in Group 1 than in the other two groups. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that tropane, piperidine, and pyridine alkaloid biosynthesis; acarbose and validamycin biosynthesis; lysine degradation; and biosynthesis of alkaloids derived from ornithine, lysine, and nicotinic acid pathways were the most significantly (p < 0.05) enriched in Group 1_vs_Group 2, while flavone and flavonol as well as anthocyanins biosynthetic pathways were the most significantly (p < 0.05) enriched in Group 1_vs_Group 3. The results from this study provide a foundation for the manipulation of the onset and rate of leaf senescence and N remobilization in wheat.

Tuning Carbon Defect in Copper Single-Atom Catalysts for Efficient Oxygen Reduction.

Defect chemistry in carbon matrix shows great potential for promoting the oxygen reduction reaction (ORR) of metal single-atom catalysts. Herein, a modified pyrolysis strategy is proposed to tune carbon defects in copper single-atom catalysts (Cu-SACs) to fully understand their positive effect on the ORR activity. The optimized Cu-SACs with controllable carbon defect degree and enhanced active specific surface area can exhibit improved ORR activity with a half-wave potential of 0.897 VRHE , ultrahigh limiting current density of 6.5 mA cm-2 , and superior turnover frequency of 2.23 e site-1 s-1 . The assembled Zn-air batteries based on Cu-SACs can also show well-retained reversibility and voltage platform over 1100 h charge/discharge period. Density functional theory calculations reveal that suitable carbon defects can redistribute charge density of Cu-N4 active sites to weaken the O-O bond in adsorbed OOH* intermediate and thus reduce its dissociation energy. This discovery offers a universal strategy for fabricating superior single-atom catalysts with high-efficiency active sites toward energy-directed applications.

Ammonium-Modified Synthesis of Vanadium Sulfide Nanosheet Assemblies toward High Sodium Storage.

The weak van der Waals interactions of the one-dimensional (1D) chainlike VS4 crystal structure can enable fast charge-transfer kinetics in metal ion batteries, but its potential has been rarely exploited in depth. Herein, a thermodynamics-driven morphology manipulation strategy is reported to tailor VS4 nanosheets into 3D hierarchical self-assembled architectures including nanospheres, hollow nanospheres, and nanoflowers. The ultrathin VS4 nanosheets are generated via 2D anisotropic growth by the strong driving force of coordination interaction from ammonium ions under microwave irradiation and then evolve into 3D sheet-assembled configurations by adjusting the thermodynamic factors of temperature and reaction time. The as-synthesized VS4 nanomaterials present good electrochemical performances as the anode materials for sodium-ion batteries. In particular, the hollow VS4 nanospheres show a specific capacity of 1226.7 mAh g-1 at 200 mA g-1 current density after 100 cycles. The hierarchical nanostructures with large specific surface area and structural stability can overcome the difficulty of sodium ions embedding into the bulk material interior and provide more reactive materials at the same material mass loading compared with other morphologies. Both experiment and DFT calculations suggest that VS4 nanosheets reduce reaction kinetic impediment of sodium ion in battery operating. This work demonstrates a way of the morphological design of 2D VS4 nanosheets and application in sodium ion storage.

Anionic Te-Substitution Boosting the Reversible Redox in CuS Nanosheet Cathodes for Magnesium Storage.

The conversion-type copper chalcogenide cathode materials hold great promise for realizing the competitive advantages of rechargeable magnesium batteries among next-generation energy storage technologies; yet, they suffer from sluggish kinetics and low redox reversibility due to large Coulombic resistance and ionic polarization of Mg2+ ions. Here we present an anionic Te-substitution strategy to promote the reversible Cu0/Cu+ redox reaction in Te-substituted CuS1-xTex nanosheet cathodes. X-ray absorption fine structure analysis demonstrates that Te dopants occupy the anionic sites of sulfur atoms and result in an improved oxidation state of the Cu species. The kinetically favored CuS1-xTex (x = 0.04) nanosheets deliver a specific capacity of 446 mAh g-1 under a 20 mA g-1 current density and a good long-life cycling stability upon 1500 repeated cycles with a capacity decay rate of 0.0345% per cycle at 1 A g-1. Furthermore, the CuS1-xTex (x = 0.04) nanosheets can also exhibit an enhanced rate capability with a reversible specific capacity of 100 mAh g-1 even under a high current density of 1 A g-1. All the obtained electrochemical characteristics of CuS1-xTex nanosheets significantly exceed those of pristine CuS nanosheets, which can contribute to the improved redox reversibility and favorable kinetics of CuS1-xTex nanosheets. Therefore, anionic Te-substitution demonstrates a route for purposeful cathode chemistry regulation in rechargeable magnesium batteries.

General metal-organic framework-derived strategy to synthesize yolk-shell carbon-encapsulated nickelic spheres for sodium-ion batteries.

Transition-metal compounds have attracted enormous attention as potential energy storage materials for their high theoretical capacity and energy density. However, the most present transition-metal compounds still suffer from severe capacity decay and limited rate capability due to the lack of robust architectures. Herein, a general metal-organic framework-derived route is reported to fabricate hierarchical carbon-encapsulated yolk-shell nickelic spheres as anode materials for sodium-ion batteries. The nickelic metal-organic framework (Ni-MOF) precursors can be in situ converted into hierarchical carbon-encapsulated Ni2P (Ni2P/C), NiS2 (NiS2/C) and NiSe2 (NiSe2/C) by phosphorization, sulfuration, and selenation reaction, respectively, and maintain their yolk-shell sphere-like morphology. The as-synthesized Ni2P/C sample can deliver much lower polarization and discharge platform, smaller voltage gap, and faster kinetics in comparison with that of the other two counterparts, and thus achieve higher initial specific capacity (3222.1/1979.3 mAh g-1) and reversible capacity of 765.4 mAh g-1 after 110 cycles. This work should provide new insights into the phase and structure engineering of carbon-encapsulated transition-metal compound electrodes via MOFs template for advanced battery systems.

Facile One-Step Microwave-Assisted Method to Synthesize Nickel Selenide Nanosheets for High-Performance Hybrid Supercapacitor.

Nanosheets structures can be employed as the most promising electrode material to enhance electrochemical performance for supercapacitors. Nickel Selenide (Ni0.85Se) nanosheets are synthesized using a rapid microwave synthesis method in a single step. The Ni0.85Se nanosheets possess a high surface area (125 m2g-1) with a hexagonal crystalline structure. It shows magnificent electrochemical properties, such as splendid specific capacitance (2530 Fg-1 at 0.5 Ag-1). An asymmetric hybrid supercapacitor is fabricated with nickel selenide nanosheets as a positive electrode and activated carbon as a negative electrode. The assembled hybrid supercapacitor displays a high energy density of 63.5 WhKg-1 at a power density of 404 WKg-1, and after 8000 cycles, only 5% capacitance is lost along with the better voltage window at 0-1.6 V.

Cuprous Self-Doping Regulated Mesoporous CuS Nanotube Cathode Materials for Rechargeable Magnesium Batteries.

Copper sulfides are broadly explored as the possible cathode materials for rechargeable magnesium batteries on account of their high theoretical capacity of 560 mAh g-1. However, the CuS cathodes usually suffer from serious capacity decay caused by structure collapse during the repeated magnesiation/demagnesiation process. Herein, we present a cuprous self-doping strategy to synthesize mesoporous CuS nanotubes with robust structural stability for rechargeable magnesium batteries and regulate their electrochemical magnesium storage behavior. Electrochemical results show that the mesoporous CuS nanotubes can exhibit high specific capacity, remarkable cycling performance, and good rate capability. The observed discharge capacity of the mesoporous CuS nanotubes could reach about 281.2 mAh g-1 at 20 mA g-1 and 168.9 mAh g-1 at 500 mA g-1. Furthermore, a remarkable ultralong-term cyclic stability with a reversible capacity of 72.5 mAh g-1 at 1 A g-1 is obtained after 550 cycles. These results demonstrate that the mesoporous nanotube structure and the simple cuprous self-doping effect could promote the practical application of copper sulfide cathode materials for rechargeable magnesium batteries.

Study on Lifestyle Evaluation Systems for the Health of Chinese Elderly.

Background/Objective: China is now faced with a serious population aging challenge, and the health of the Chinese elderly is becoming an imminent concern. Consequently, it is critical to establish a lifestyle evaluation system for promoting the health of the Chinese elderly. Methods: Interviews with experts and questionnaire surveys were conducted. Factor analysis, analytic hierarchy process, and statistical analyses were also adopted in this study. Results: Besides evaluation metrics and standards, a two-level category system including 50 indices and associated weights from three level 1 categories (physical and mental health and social wellbeing) and thirteen level 2 categories were obtained. Discussion and Conclusions: Based on the confirmatory factor analysis and Cronbach's test, such an evaluation system excels in effectiveness and reliability, and is ready to be popularized in Chinese society. We expect that the Chinese elderly will benefit from our system and that it will lead to a healthy lifestyle accordingly.