First-Principles Study of High-Entropy Sulfides and their Alkali Metal-Doped Modification as Cathode Material for Sodium-Ion Batteries.

High-entropy materials (HEMs) have been explored as high-capacity cathode materials for sodium-ion batteries (SIBs) due to their excellent structural stability and abundant metal redox sites. Among them, high-entropy sulfides (HESs) have greater potential and more extensive research than high-entropy oxides, as they exhibit higher charging voltage and theoretical capacity as cathodes. Furthermore, alkali metal doping of HESs can further enhance their performance and broaden their application fields. Inspired by the cocktail effect of HEMs, we performed the first theoretical calculation of the properties of Na(MnFeCoNi)1/2S and its Li-doped derivative, Na7/8Li1/8(MnFeCoNi)1/2S, to understand their potential as SIB cathode materials. Using density functional theory based on first principles, we investigated the structure and electronic characteristics of Na(MnFeCoNi)1/2S and Na7/8Li1/8(MnFeCoNi)1/2S, and calculated their theoretical voltage and capacity, respectively. Compared with Na(MnFeCoNi)1/2S, Na7/8Li1/8(MnFeCoNi)1/2S showed better electronic performance in reducing the band gap and increasing the density of states, ultimately providing a specific capacity of 160.3 mAh ⋅ g-1 and a charging voltage of 4.85 V in sodium-ion storage. Moreover, Na7/8Li1/8(MnFeCoNi)1/2S exhibited remarkable structural stability throughout the sodium-ion deintercalation process, thus it can be reasonably concluded that Na7/8Li1/8(MnFeCoNi)1/2S can serve as an excellent cathode material for future SIB applications.

Element screening of metal sites in Fe-based Prussian blue framework materials for ammonium ion battery applications: a first-principles study.

Prussian blue framework materials are expected to be the next generation of electrode materials for commercial batteries because their three-dimensional framework structures facilitate the rapid transport and storage of ions and a variety of redox processes. This work compared the calculations of the model before and after the dispersion correction, and the model considering the effect of van der Waals force was more stable. In addition, the distances between H, C and N atoms were within the range of van der Waals force. Thus it was confirmed that NH4+ was adsorbed on the Ax site in the Prussian blue framework material (AxMa[Mb(CN)6]) by van der Waals interaction, and the charge transfer was mainly achieved by the interaction between the H atom in NH4+ and the N atom in the Prussian blue framework. On this basis, the properties of NH4+ batteries were theoretically screened for the Fe-based Prussian blue analogues (PBAs) with different Ma elements (Ma = Co, Cu, Fe, Mg, Mn, Ni, V or Zn). Considering the regulating effect of different metal elements on the electronic structures of PBAs, MgFe and ZnFe PBAs as the electrode materials of NH4+ batteries are expected to show excellent electrochemical energy storage performance in organic electrolytes.

Computational screening toward transition metal doped vanadium carbides in different crystal planes for efficient hydrogen evolution: a first-principles study.

In the present work, we evaluated the hydrogen evolution reaction (HER) performance of transition metal (Co, Fe, Ni, Mn, and Mo) doped vanadium carbides (VC). In addition, the doping atoms were screened separately on the (100), (110) and (111) crystal planes to analyze the differences in HER activities. Among all the calculated models, Mn-VC(100) exhibited the best catalytic hydrogen evolution performance with a Gibbs free energy for hydrogen adsorption (ΔGH*) of 0.0012 eV. Doping Mn greatly improved the HER performance of VC(100) by enhancing the adsorption of hydrogen on the catalyst surface. The analysis of the electronic density of states and charge transfer confirmed that doping transition metal atoms into the surfaces of the VC model successfully optimized the electronic structure and promoted catalytic reaction kinetics. Besides, the relationship between the catalytic activity and pH value of different models was considered, and doping Co atoms on the (100) crystal plane could effectively modify the pH value range applicable for the efficient HER. Interestingly, even if the same metal atoms were doped, various active sites of VC models exhibited different catalytic performances due to disparate exposed crystal planes and pH values. This indicates that the main exposed crystal surfaces and the pH range of application need to be considered when selecting the appropriate doping element for the catalyst.

Association between a high triglyceride-glucose index and chronic kidney disease in adult patients with latent autoimmune diabetes.

BACKGROUND: Insulin resistance (IR) is one of the risk factors for chronic kidney disease (CKD) and diabetes. The triglyceride-glucose (TyG) index is considered a reliable alternative marker of IR. We investigated the correlation between the TyG index and the severity of CKD in patients with latent autoimmune diabetes in adults (LADA). METHODS: This cross-sectional study included 288 patients with LADA in the department of endocrinology at our hospital between January 2018 and January 2022. The TyG index was calculated as Ln [TG (mg/dl) × fasting blood glucose (FBG) (mg/dl) / 2]. All individuals were divided into either a LADA + CKD group or a LADA + non-CKD group according to the presence or absence of CKD. A correlation analysis, logistic regression analysis and receiver operating characteristics curve analysis were performed. RESULTS: A total of 130 (45.1%) participants were identified as having CKD. Compared with the non-CKD group, the CKD group had a longer disease duration and a higher proportion of smokers; patients were more likely to have hypertension and higher serum creatinine, triglyceride, cholesterol, low-density lipoprotein cholesterol, FBG, uric acid estimated glomerular filtration rates (eGFR) and TyG levels as well as lower high-density lipoprotein cholesterol levels (all P < 0.05). The positive relationship between the TyG index and the urinary albumin/creatinine ratio was significant (r = 0.249, P = 0.010). There was also a significant correlation between the TyG index and the eGFR (r = - 0.211, P = 0.034) after adjusting for confounding factors. The area-under-the-curve value of the TyG index was 0.708 (95% confidence interval: 0.61-0.81, P < 0.001). CONCLUSIONS: The TyG index is significantly associated with the severity of CKD in patients with LADA. This conclusion supports the clinical application of the TyG index for the assessment of kidney disease in patients with LADA.

The relationship between red blood cell distribution width and islet ß-cell function indexes in patients with latent autoimmune diabetes in adults.

AIMS: The objective of this study is to explore the relationship between red blood cell distribution and islet ß-cell function indexes in patients with Latent Autoimmune Diabetes in Adults. METHODS: A total of 487 LADA patients were enrolled in this cross-sectional study. Patients were divided into three groups according to RDW tertiles. Clinical and laboratory measurements of age, height, weight, duration of diabetes, blood pressure, RDW, glycosylated hemoglobin A1c (HbA1c), C-peptide and blood lipids were performed. Homeostasis model assessment of insulin resistance (HOMA-IR) and homeostasis model assessment of ß-cell function (HOMA-ß) were assessed using homeostasis model assessment (HOMA) based on fasting blood glucose (FBG) and fasting C-peptide index (FCP). Correlations and multiple linear regressions were implemented to determine the association of RDW and islet function indexes. RESULTS: As the increase of serum RDW level, the presence of ß-cell secretion increased(P < 0.05). Correlation analysis indicated that there were significant correlations between RDW and male sex, age, duration, TG, Cr, FCP, and HOMA-ß in all subjects. Multiple linear regressions indicated that RDW was significantly correlated with HOMA-ß in the total population in both unadjusted and adjusted analysis. This finding could be reproduced in the subgroup of low GAD titers for HOMA-ß. RDW were significantly associated with HbA1c in LADA patients with high GAD titers, but the correlation was not found in subgroup with low GAD titers in either unadjusted analyses or adjusted analysis. CONCLUSIONS: RDW is associated with ß-cell function assessed by HOMA-ß after adjusting for covariates in LADA patients with low GAD titers.

Tetrahedral DNA framework assisted rotational paper-based analytical device for differential detection of SARS-CoV-2 and influenza A H1N1 virus.

Coronavirus disease 2019 (COVID-19) and influenza A are two respiratory infectious diseases with similar clinical manifestations. Because of the complex global epidemic situation of COVID-19, the distinction and diagnosis of COVID-19 and influenza A infected persons is crucial for epidemic prevention and control. In this study, tetrahedral DNA framework (TDF) was combined with a rotational paper-based analytical device, and the color change generated by the reaction between horseradish peroxidase (HRP) and 3,3'5,5'-tetramethylbenzidine (TMB)-H2O2 was used for grayscale signal analysis by ImageJ software. The quantitative detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A H1N1 virus were realized simultaneously. Under the optimal conditions, the paper-based analytical device showed a good linear relationship between the two viruses in the range of 10-14-10-8g/mL, and the two viruses were not affected by cross reaction. This sensor provides a convenient and reliable method for clinical rapid differentiation and diagnosis of COVID-19 and influenza A.

Edge engineering on layered WS2 toward the electrocatalytic reduction of CO2: a first principles study.

Transition-metal dichalcogenides (TMDCs) have been modified to show excellent electrocatalytic performance for the CO2 reduction reaction (CO2RR). However, little research has been reported on the edge modification of WS2 and its electrocatalytic CO2RR. In this work, the edge structure of WS2 with W atoms exposed in the top layer was established by density functional theory calculations. Through using WS2-xTM-y (x = 1, 2 or 3; y = 1 or 2; TM = Zn, Fe, Co or Ni) models by doping TM atoms on the top layer of WS2, the effects of dopant species, doping concentration and adsorption sites on their electrocatalytic activity were investigated. Among the models, the active site for the CO2RR is the W atoms. The doping of TM atoms would affect the bond strength between W and S atoms. After the doping of TM atoms in WS2-2TM-1 ones, the electrical conduction of S atoms and the underlying W atoms can greatly be improved. Thus the catalytic activities can be significantly increased, in which the WS2-2Zn-1 model shows the best catalytic activity. The limiting potential (UL) of the CO2RR to CO on the WS2-2Zn-1 model is -0.51 V and the Gibbs energy change (ΔG) for the adsorption of intermediates on the WS2-2Zn-1 model is ΔG(COOH*) = -0.37 and ΔG(CO*) = -0.51 eV, respectively. Solvation correction showed that WS2-2Zn-1 could maintain good catalytic performance in a wide range of pH values. The present results may provide a theoretical basis for the design and synthesis of novel electrocatalysts with high performance for the CO2RR.

One-Step Calcination to Gain Exfoliated g-C3N4/MoO2 Composites for High-Performance Photocatalytic Hydrogen Evolution.

The difficulty of exposing active sites and easy recombination of photogenerated carriers have always been two critical problems restricting the photocatalytic activity of g-C3N4. Herein, a simple (NH4)2MoO4-induced one-step calcination method was successfully introduced to transform bulk g-C3N4 into g-C3N4/MoO2 composites with a large specific surface area. During the calcination, with the assistance of NH3 and water vapor produced by ammonium molybdate, the pyrolytical oxidation and depolymerization of a g-C3N4 interlayer were accelerated, finally realizing the exfoliation of the g-C3N4. Furthermore, another pyrolytical product of ammonium molybdate was transformed into MoO2 under an NH3 atmosphere, which was in situ loaded on the surface of a g-C3N4 nanosheet. Additionally, the results of photocatalytic hydrogen evolution under visible light show that the optimal g-C3N4/MoO2 composite has a high specific surface area and much improved performance, which is 4.1 times that of pure bulk g-C3N4. Such performance improvement can be attributed to the full exposure of active sites and the formation of abundant heterojunctions. However, with an increasing feed amount of ammonium molybdate, the oxidation degree of g-C3N4 was enhanced, which would widen the band gap of g-C3N4, leading to a weaker response ability to visible light. The present strategy will provide a new idea for the simple realization of exfoliation and constructing a heterojunction for g-C3N4 simultaneously.

Ni Foam-Supported Tin Oxide Nanowall Array: An Integrated Supercapacitor Anode.

A novel product consisting of a homogeneous tin oxide nanowall array with abundant oxygen deficiencies and partial Ni-Sn alloying onto a Ni foam substrate was successfully prepared using a facile solvothermal synthesis process with subsequent thermal treatment in a reductive atmosphere. Such a product could be directly used as integrated anodes for supercapacitors, which showed outstanding electrochemical properties with a maximum specific capacitance of 31.50 mAh·g-1 at 0.1 A·g-1, as well as good cycling performance, with a 1.35-fold increase in capacitance after 10,000 cycles. An asymmetric supercapacitor composed of the obtained product as the anode and activated carbon as the cathode was shown to achieve a high potential window of 1.4 V. The excellent electrochemical performance of the obtained product is mainly ascribed to the hierarchical structure provided by the integrated, vertically grown nanowall array on 3D Ni foam, the existence of oxygen deficiency and the formation of Ni-Sn alloys in the nanostructures. This work provides a general strategy for preparing other high-performance metal oxide electrodes for electrochemical applications.

A label-free protamine-assisted colorimetric sensor for highly sensitive detection of S1 nuclease activity.

A label-free, sensitive, simple and general colorimetric method was reported to monitor S1 nuclease activity based on protamine-assisted aggregation of gold nanoparticles (AuNPs). Here, protamine, a linear polycation, was used as a medium for causing the aggregation of negatively charged AuNPs by electrostatic interactions, resulting in changes in the surface plasmon resonance (SPR) absorption bands as well as the color of AuNPs. Here, the AuNPs were employed as an indicator to detect the level of S1 nuclease in the solution. Substrate DNA could be cleaved into small fragments by the specific S1 nuclease, which effectively prevents the electrostatic interaction between DNA and protamine and thus facilitates the interaction between protamine and AuNPs. The quantitative analysis of S1 nuclease activity can be performed via directly measuring the changes in the absorption spectra of the AuNPs. Using S1 nuclease as a model analyte, the limit of detection was estimated to be 1.0 × 10-4 U mL-1. Furthermore, the proposed concept has been successfully applied in S1 nuclease analysis of serum samples, offering an ultrasensitive strategy for the speedy detection of the nuclease activity and providing a new avenue for high-throughput screening of nucleases and drugs with potential inhibition properties.

Facile synthesis of a cyclodextrin-metal organic framework decorated with Ketjen Black and platinum nanoparticles and its application in the electrochemical detection of ofloxacin.

A facile and novel method was developed to improve the conductivity of a cyclodextrin-metal organic frameworks (CD-MOFs) by modifying it with Ketjen Black (KB) and platinum nanoparticles (PtNPs). The structural morphology and composition of this PtNPs/KB/CD-MOFs nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, elemental mapping, and Raman spectroscopy. The sensor was then evaluated for its ability to detect ofloxacin using cyclic voltammetry, and the results showed that the PtNPs/KB/CD-MOF had high sensitivity, satisfactory stability and good reproducibility. In addition, a great linear range was obtained with a concentration range of 0.08-100 µM and a low detection limit of 0.037 µM (S/N = 3). Therefore, the prepared electrochemical sensor could be successfully used to detect ofloxacin in serum.

Surface selectivity of Ni3S2 toward hydrogen evolution reaction: a first-principles study.

Exploring materials with high catalytic performance toward hydrogen evolution reaction (HER) is of importance for the development of clean hydrogen energy, and their surface structure is essential for this function. In this study, using density functional theory (DFT), we reported a comprehensive study on the phase stability, surface structures, electronic properties and HER catalytic properties of the low-index surfaces of Ni3S2, including the (0001), (101[combining macron]0), (101[combining macron]1), (112[combining macron]0) and (112[combining macron]1) planes with different terminations. Our calculated results demonstrate that S-rich surfaces and several stoichiometric surfaces of Ni3S2 are thermodynamically stable, including (0001)A, (101[combining macron]0)A, (112[combining macron]0)C, (101[combining macron]0)C, (101[combining macron]0)B and (112[combining macron]1)A surfaces. Among the six stable surface structures, the (0001)A, (101[combining macron]0)B and (101[combining macron]0)C surfaces of Ni3S2 are indispensable for high HER performance because of their high catalytic activity, suitable potential and high thermodynamic stability. The calculated changes of Gibbs free energy (ΔGH*) of the Top S2 site on (0001)A, Hollow Ni2S3S4 site on (101[combining macron]0)C, and Bridge Ni1Ni3 site and Hollow Ni2S1S2 site on (101[combining macron]0)B are -0.143, 0.122, 0.012, and -0.112 eV, respectively, comparable with or even better than those of Pt(111) (-0.07 eV). In addition, the possible Volmer-Heyrovsky and Volmer-Tafel processes on the considered surfaces are also investigated. When the overpotential is in the range of 0 to 300 mV, the density of active sites on the (101[combining macron]0)B surface of Ni3S2 is found to be the highest. This work provides significant insights on the surface selectivity of Ni3S2 toward HER and provides a route to optimize the performance of Ni3S2 with exposed surfaces.

A graphene oxide/gold nanoparticle-based amplification method for SERS immunoassay of cardiac troponin I.

Cardiac troponin I (cTnI) was considered as the "gold standard" for acute myocardial infarction (AMI) diagnosis owing to its superior cardiac specificity for cardiac damage and showing little or no changes in patients with a skeletal muscle disease or trauma. Herein, a new signal amplification surface-enhanced Raman scattering (SERS) platform was developed for recognition and detection of cTnI by using gold nanoparticles (AuNPs), graphene oxide (GO) and magnetic beads (MB). Here, antibody/Raman reporter labeled AuNP-functionalized GO were employed as both SERS nanotags and signal amplification carriers. Monoclonal antibody modified MB were applied as the capture probe and separation agents. In the presence of cTnI, sandwich type immunocomplexes, "capture probe/target/SERS nanotags", were formed through antibody-antigen-antibody interactions. Due to the strong SERS enhancement ability of the designed GO/AuNP complexes and a high binding chance between cTnI and the GO/AuNP complexes, the proposed SERS-based immunoassay could selectively detect cTnI with a high sensitivity (detection limit of 5 pg mL-1) and a good linearity was obtained in a range of 0.01-1000 ng mL-1. In addition, this method was also successfully applied for detecting cTnI in serum substitute media with a similar linear range. Furthermore, this strategy can be constructed with different kinds of antibodies and Raman reporters, and thus can be easily used for simultaneous detection of multiple biomarkers. Therefore, this proposed SERS-based signal amplification technique shows strong potential for the clinical diagnosis of AMI disease.

One-Step Fabrication of Monolithic Electrodes Comprising Co9 S8 Particles Supported on Cobalt Foam for Efficient and Durable Oxygen Evolution Reaction.

A very easy and cost-effective approach to the fabrication of monolithic Co9 S8 water oxidation electrodes (Co@Co9 S8 ), fabricated by one-step hydrothermal treatment of commercially available cobalt foam in the presence of thiourea, is reported. The morphology, crystal structure, microstructure, and composition of as-fabricated Co@Co9 S8 electrodes were examined by using scanning electron microscopy (SEM), powder X-ray diffractometry (XRD), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS), and their electrochemical properties were investigated by cyclic voltammetry (CV), chronopotentiometry (CP), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). When used to catalyze the oxygen evolution reaction (OER) in alkaline solution, the Co@Co9 S8 electrode with an optimal Co9 S8 loading exhibits outstanding catalytic activity, requiring a low overpotential of 350 mV to deliver an anodic current density of 10 mA cm-2 and showing fast kinetics for OER with a small Tafel slope (55 mV dec-1 ) and charge-transfer resistance (0.44â€…Ω cm-2 ), which outperforms many sulfide-based OER catalysts and some state-of-the-art noble metal catalysts recently reported in the literature. Importantly, the electrodes show excellent long-term stability, and are capable of operating at both a low current density and a high current density relevant to industrial water electrolysis up to 100 hours.

Association of height with peripheral arterial disease in type 2 diabetes.

OBJECTIVE: To investigate whether height is associated with peripheral arterial disease (PAD) in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: This was an observational study performed in 4,528 Chinese patients with type 2 diabetes. Anthropometric measures and the ankle-brachial index (ABI) were performed on each subject. PAD was defined as those patients with a history of revascularization or amputation due to ischemia, or an ABI <0.9. RESULTS: A total of 23.3 % of T2DM patients had PAD (men 22.9 % and women 23.7 %). The mean age and height were 57.8 ± 12.5 years and 170.5 cm for men, and 60.0 ± 11.7 years and 158.9 cm for women, respectively. The ABI and frequency of PAD were higher with decreasing height quartiles. An inverse association was observed between height- and gender-adjusted risk of PAD. This relationship remained unchanged following further adjustment for potential confounders. Subjects in the shortest stature group had of 1.174 times higher risk of PAD for men and 1.143 times for women, compared with those in the tallest stature group. The multivariate adjusted hazard ratios (95 % CI) of PAD for a 10-cm height increase were 0.85 (95 % CI 0.78-0.94). CONCLUSION: A short stature seems to be associated with higher risk of PAD in Chinese diabetic patients. However, the cross-sectional nature of the study limits conclusions regarding the direction or causality. Further longitudinal study is warranted in this and other ethnic groups.

Nonlinear saturable absorption of vertically stood WS2 nanoplates.

We report the nonlinear optical (NLO) properties of vertically stood WS2 nanoplates excited by 532-nm picosecond laser light. The nanoplates were synthesized by a no-catalyst thermal evaporation process. Raman spectroscopy and x-ray diffraction pattern indicate that the nanoplates are of high crystal quality. The nanoplates exhibit large nonlinear saturable absorption but negligible nonlinear refraction. Mechanisms of the NLO response are proposed.

Microstructure and nonohmic properties of SnO2-Ta2O5-ZnO system doped with ZrO2.

The microstructure and nonohmic properties of SnO2-Ta2O5-ZnO varistor system doped with different amounts of ZrO2 (0-2.0 mol%) were investigated. The proposed samples were sintered at 1400°C for 2 h with conventional ceramic processing method. By X-ray diffraction, SnO2 cassiterite phase was found in all the samples, and no extra phases were identified in the detection limit. The doping of ZrO2 would degrade the densification of the varistor ceramics but inhibit the growth of SnO2 grains. In the designed range, varistors with 1.0 mol% ZrO2 presented the maximum nonlinear exponent of 15.9 and lowest leakage current of 110 µA/cm², but the varistor voltage increased monotonously with the doping amount of ZrO2.

Spontaneous emission in paired graphene plasmonic waveguide structures.

The coupling between a single emitter and surface plasmons in paired graphene layers and in paired graphene ribbons are studied. For paired graphene layers, the coupling between surface plasmons in graphene layers is strong at low photon energy and small gap between layers, which results in strong enhancement of the emitter's emission. The excitation efficiency of surface plasmons by a single emitter can be increased to nearly 1 in paired graphene layers. With the increase of the photon energy, emitter's emission in paired layers is weakened and could be lower than that in graphene monolayer. For graphene paired ribbons, numerical simulations show similar properties of emission enhancement and high excitation efficiency of surface plasmons. The emission enhancement and the excitation efficiency of surface plasmons can be improved by narrowing the ribbon width.

Ultralow-background SERS substrates for reliable identification of organic pollutants and degradation intermediates.

Chemical methods for preparing SERS substrates have the advantages of low cost and high productivity, but the strong background signals from the substrate greatly limit their applications in characterization and identification of organic compounds. Herein, we developed a one-step synthesis method to prepare silver nanoparticle substrates with ultralow SERS background using anionic ligands as stabilizing agents and applied the SERS substrate for the reliable and reproducible identification of typical organic pollutants and corresponding degradation intermediates. The synthesis method shows excellent universality to different reducing agents cooperating with different anionic ligands (Cl-, Br-, I-, SCN-). As model applications, the machine learning algorithm can realize the precise prediction of six organophosphorus pesticides and eight sulfonamide antibiotics with 100% accuracy based on SERS training data. More importantly, the ultralow-background SERS substrate enables one to detect and identify the time-dependent degradation intermediates of organophosphorus pesticides by combining them with density functional theory (DFT) calculations. All the results indicate that the ultralow-background SERS substrate will greatly push the development of SERS characterization applications.