Apically guiding electron/mass transfer reaction induced by Ag/FeN_(x)Mott-Schottky effect within a hollow star reactor toward high performance zinc-air batteries

The disparity in the transfer of carriers(electrons/mass)during the reaction in zinc-air batteries(ZABs)results in sluggish kinetics of the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),along with elevated overpotentials,thereby imposing additional constraints on its utilization.Therefore,the pre-design and target-development of inexpensive,high-performance,and long-term stable bifunctional catalysts are urgently needed.In this work,an apically guiding dual-functional electrocatalyst(Ag-FeN_(x)-N-C)was prepared,in which a hierarchical porous nitrogen-doped carbon with three-dimensional(3D)hollow star-shaped structure is used as a substrate and high-conductivity Ag nanoparticles are coupled with iron nitride(FeN_(x))nanoparticles.Theoretical calculations indicate that the Mott-Schottky heterojunction as an inherent electric field comes from the two-phase bound of Ag and FeN_(x),of which electron accumulation in the FeN_(x)phase region and electron depletion in the Ag phase region promote orientated-guiding charge migration.The effective modulation of local electronic structures felicitously reforms the d-band electron-group distribution,and intellectually tunes the masstransfer reaction energy barriers for both ORR/OER.Additionally,the hollow star-s haped hierarchical porous structure provides an apical region for fast mass transfer.Experimental results show that the halfwave potential for ORR is 0.914 V,and the overpotential for OER is only 327 mV at 10 mA cm^(-2).A rechargeable ZAB with Ag-FeN_(x)-N-C as the air cathode demonstrates long-term cycling performance exceeding 1500 cycles(500 h),with a power density of 180 mW cm^(-2).Moreover,when employing AgFeN_(x)-N-C as the air cathode,flexible ZABs demonstrate a notable open-circuit voltage of 1.42 V and achieve a maximum power density of 65.6 mW cm^(-2).Ag-FeN_(x)-N-C shows guiding electron/mass transfer route and apical reaction microenvironment for the electrocatalyst architecture in the exploration prospects of ZABs.

Iron(Fe,Ni,Co)-based transition metal compounds for lithium-sulfur batteries:Mechanism,progress and prospects

Lithium-sulfur batteries(LSBs)have a high theoretical capacity,which is considered as one of the most promising high-energy-density secondary batteries due to the double electrons reaction of sulfur.However,the shuttle effects of lithium polysulfides(Li PSs)and sluggish redox kinetics lead to their materials capacity loss and cycle stability deterioration,which restrains LSBs commercialization.Metallic compounds as additions can improve the electrochemical performance of the Li-S system,through the trap of Li PSs and accelerate the conversion of the soluble Li PSs.Among of them,the iron group elements(Fe,Ni,Co)-based compounds are the promising materials for the LSBs,due to their unique outer electronic structure and its tunable properties,low cost,abundant in the earth,environmental benignity,controllable and scalable prepared,and so on.In this review,we have made a summary for iron-based compounds to capture Li PSs according to lithium bond,sulfur bond and magnetic force.The type of iron-based compound including oxides,sulfides,nitrides,phosphides,carbides,and so on,and we have investigated the electrocatalytic mechanism of these materials.Besides,some improvement strategies are proposed,such as the engineering of the special micro/nanostructure,defect concentrations,band structures,and heterostructures.We hope to shed an in-depth light on the rationally design and fabrication of robust,commercial and stable materials for high-performance LSBs.

Designing Electrochemical Nanoreactors to Accelerate Li_(2)S_(1/2) Three-Dimensional Growth Process and Generating More Li_(2)S for Advanced Li–S Batteries

With advantages of low costs and high energy density,Li–S batteries are considered as one of the most promising energy storage devices.However,Li_(2)S_(2) with a high dissociation energy and insulative properties is hard to convert into Li_(2)S,resulting in underutilization of sulfur capacity.Herein,Co-Mo_(2)C@C yolk–shell spheres as nanoreactors were designed to confront this challenge rationally.The Co-Mo_(2)C@C-induced Li_(2)S_(1/2) nucleation and growth in the three-dimensional process and the cathode produced more Li_(2)S after full discharge.Experimental studies and theoretical calculations reveal that the conversion barrier from Li_(2)S_(2) into Li_(2)S was lowered while the diffusion of lithium ions and electron transfer accelerated when using the Co-Mo_(2)C@C catalyst.Based on the above advantages,the Co-Mo_(2)C@C/S cathode exhibits a high reversible capacity and excellent cyclic stability,such as an initial specific capacity of 1200 mAh g^(−1) at 0.1 C with 709 mAh g^(−1) at 1.0 C after 1000 cycles with a low capacity fading rate of 0.04%per cycle.Even at high densities of 3.0 C and 5.0 C,the specific capacities are 647.6 and 557.7 mAh g^(−1) after 400 cycles,respectively.Impressively,it also shows ca.770 and 900 mAh g^(−1) at 0.2 C after 50 cycles with high sulfur loadings of 4.2 and 5.1 mg cm−2,respectively.The present work may provide new insights into the design of nanoreactors to promote Li_(2)S_(1/2) growth in a three-dimensional process and accelerate conversion from solid Li_(2)S_(2) to solid Li_(2)S in high performance Li–S batteries.

Artifcial Intelligence Empowered Nuclear Medicine and Molecular Imaging in Cardiology:A State‑of‑the‑Art Review

Nuclear medicine and molecular imaging plays a signifcant role in the detection and management of cardiovascular disease(CVD).With recent advancements in computer power and the availability of digital archives,artifcial intelligence(AI)is rapidly gaining traction in the feld of medical imaging,including nuclear medicine and molecular imaging.However,the complex and time-consuming workfow and interpretation involved in nuclear medicine and molecular imaging,limit their extensive utilization in clinical practice.To address this challenge,AI has emerged as a fundamental tool for enhancing the role of nuclear medicine and molecular imaging.It has shown promising applications in various crucial aspects of nuclear cardiology,such as optimizing imaging protocols,facilitating data processing,aiding in CVD diagnosis,risk classifcation and prognosis.In this review paper,we will introduce the key concepts of AI and provide an overview of its current progress in the feld of nuclear cardiology.In addition,we will discuss future perspectives for AI in this domain.

Functional characterization,structural basis,and protein engineering of a rare flavonoid 2′-O-glycosyltransferase from Scutellaria baicalensis

Glycosylation is an important post-modification reaction in plant secondary metabolism,and contributes to structural diversity of bioactive natural products.In plants,glycosylation is usually catalyzed by UDP-glycosyltransferases.Flavonoid 2′-O-glycosides are rare glycosides.However,no UGTs have been reported,thus far,to specifically catalyze 2′-O-glycosylation of flavonoids.In this work,UGT71AP2 was identified from the medicinal plant Scutellaria baicalensis as the first flavonoid 2′-O-glycosyltransferase.It could preferentially transfer a glycosyl moiety to 2′-hydroxy of at least nine flavonoids to yield six new compounds.Some of the 2′-O-glycosides showed noticeable inhibitory activities against cyclooxygenase 2.The crystal structure of UGT71AP2(2.15Å)was solved,and mechanisms of its regio-selectivity was interpreted by pKa calculations,molecular docking,MD simulation,MM/GBSA binding free energy,QM/MM,and hydrogen‒deuterium exchange mass spectrometry analysis.Through structure-guided rational design,we obtained the L138T/V179D/M180T mutant with remarkably enhanced regio-selectivity(the ratio of 7-O-glycosylation byproducts decreased from 48%to 4%)and catalytic efficiency of 2′-O-glycosylation(kcat/Km,0.23 L/(s·μmol),12-fold higher than the native).Moreover,UGT71AP2 also possesses moderate UDP-dependent de-glycosylation activity,and is a dual function glycosyltransferase.This work provides an efficient biocatalyst and sets a good example for protein engineering to optimize enzyme catalytic features through rational design.

Partial discharge measurement and analysis under lightning impulse superimposed DC voltage in SF6 gas

The presence of lightning impulses(LIs)on the DC waveform can seriously influence the insulation performance of a GIL system.The waveshape can be a superposition of the DC and impulse waveform.In this study,the behaviour of partial discharge(PD)on an epoxy surface is investigated under DC and LI superimposed voltage in SF6.The lightning impulses with different polarities are superimposed on the epoxy surface under both positive and negative DC voltages,respectively.Positive lightning impulses are superimposed on a negative DC voltage with a 90%of the partial discharge inception voltage(PDIV)magnitude.The number and amplitude of the PDs are used to evaluate the insulation performance.The experimental results show that the LI with a different polarity applied to DC can excite the PDs on the epoxy surface.The excitation effect of positive LI superimposed on negative DC is more significant.According to the impulse amplitude and PD characteristics,the influence of superimposed LI on PD excitation can be divided into three stages.As the superimposed LI increases,the amplitude of the excited PD increases gradually,while the PD number first increases and then decreases.This study is expected to provide reference for manufacture and protection of power equipment.

Phase Engineering of CoMo0_(4)Anode Materials toward Improved Cycle Life for Li^(+)Storage

Anode materials based on conversion reactions usually possess high energy densities for lithium-ion batteries(LIBs).However,they suffer from poor rate performance and cycle life due to serious volume changes.Herein,α/β-CoMo04 heterogeneous nanorods are synthesized via a facile co-precipitation method,and further are phase-engineered through varying calcination temperature,accomplishing the obviously improved cycle life and rate performance as anodes for LIBs.When evaluated at a current density of 1.0 A·g^(-1)the optimal nanorods with anα/βphase ratio of 6.0 afford the reversible capacity of 1143.6 mAh·g^(-1)after 200 cycles,outperforming most of recently reported bimetal oxides.Li^(+)storage mechanism is further analyzed by using in-situ X-ray diffraction and ex-situ transition electronic microscopy.It's revealed thatβ-CoMoO_(4)follows a one-step conversion reaction;whileα-CoMo0_(4)proceeds an intercalation pathway before the conversion reaction.Grading storage of Li^(+)would alleviate the volume effect of heterostructuredα/β-CoMo0_(4),forming electronically conductive network evenly composed of Co and Mo nanograins to enable the reversible electrochemical conversion.This work is anticipated to give some hints for the rational design of high-performance energy materials.

A highly selective C-rhamnosyltransferase from Viola tricolor and insights into its mechanisms

C-Glycosides are important natural products with various bioactivities.In plant biosynthetic pathways,the C-glycosylation step is usually catalyzed by C-glycosyltransferases(CGTs),and most of them prefer to accept uridine 5’-diphosphate glucose(UDP-Glc)as sugar donor.No CGTs favoring UDP-rhamnose(UDP-Rha)as sugar donor has been reported,thus far.Herein,we report the first selective C-rhamnosyltransferase VtCGTc from the medicinal plant Viola tricolor.VtCGTc could efficiently catalyze C-rhamnosylation of 2-hydroxynaringenin 3-C-glucoside,and exhibited high selectivity towards UDP-Rha.Mechanisms for the sugar donor selectivity of VtCGTc were investigated by molecular dynamics(MD)simulations and molecular mechanics with generalized Born and surface area solvation(MM/GBSA)binding free energy calculations.Val144 played a vital role in recognizing UDP-Rha,and the V144T mutant could efficiently utilize UDP-Glc.This work provides a new and efficient approach to prepare flavonoid C-rhamnosides such as violanthin and iso-violanthin.

术前预康复对全膝关节置换术后早期功能恢复效果的影响

目的探讨在加速康复外科多学科协作模式下术前预康复对膝关节置换术后早期功能恢复效果的影响。方法回顾性分析2019年9月至2021年12月在晋江市医院骨科接受全膝关节置换术患者51例的临床资料,将51例患者中按术前是否采用术前预康复分为观察组(24例)和对照组(27例),在行膝关节置换术前进行预康复的设为观察组,术前未进行预康复的设为对照组。观察组在办理入院手续后,前往康复门诊进行康复评估,并在同一个康复师指导下行个性化康复训练,后续手术后康复师跟进术后康复。对照组则无术前预康复,术后康复师及时介入康复,康复师在术后2 d和5 d分别对患者进行康复评分(HSS评分、运动疼痛目测类比评分等)。主要观察指标:患者术后2 d、5 d膝关节活动度(range of motion,ROM);术后2 d、5 d膝关节功能评价表(hospital for special surgery knee score,HSS);术后5 d运动疼痛目测类比评分(visual analogous scale,VAS);术后至出院天数;术后并发症发生率;术后康复科门诊回访情况等。结果观察组与对照组术后2 d ROM评分差异无统计学意义(P>0.05),两组术后5 d ROM评分差异有统计学意义[(100.08±7.75)分比(88.44±16.09)分,t=3.34,P=0.002];术后2 d两组HSS评分差异无统计学意义(P>0.05),术后5 d两组HSS评分差异有统计学意义[(62.84±5.78)分比(57.09±6.53)分,t=3.31,P=0.002];术后5 d两组VAS(运动时)评分差异有统计学意义[(3.42±1.02)分比(5.37±1.15)分,t=-6.39,P<0.001];两组术后至出院天数差异无统计学意义(P>0.05)。术后并发症发生率差异无统计学意义(P>0.05),两组术后康复科门诊回访情况差异有统计学意义[(7/17)比(1/26),χ^(2)=4.45,P=0.035]。结论加速康复外科多学科协作模式下术前预康复有助于提高全膝关节置换术患者的早期功能水平,降低术后康复疼痛感,提高患者术后康复依从性,提升患者对手术的满意度。

Diamond/β-SiC film as adhesion-enhanced interlayer for top diamond coatings on cemented tungsten carbide substrate

In present work, diamond/β-SiC composite interlayers were deposited on cemented tungsten carbide（WC-6%Co） substrates by microwave plasma enhanced chemical vapor deposition（MPCVD） using H2,CH4 and tetramethylsilane（TMS） gas mixtures. The microstructure, chemical bonding, element distribution and crystalline quality of the composite interlayers were systematically characterized by means of field-emission scanning electron microscopy（FE-SEM）, X-ray diffraction（XRD）, X-ray photoelectron spectrometer（XPS）, electron probe microanalysis（EPMA）, Raman spectroscopy and transmission electron microscropy（TEM）. The influences of varying TMS flow rates on the diamond/β-SiC composite interlayers were investigated. Through changing the TMS flow rates in the reaction gas, the volume fraction of β-SiC in the composite interlayers were tunable in the range of 12.0%–68.1%. XPS and EPMA analysis reveal that the composite interlayers are composed of C, Si element with little cobalt distribution. The better crystallinity of the diamond in the composite is characterized based on the Raman spectroscopy, which are helpful to deposit top diamond coatings with high quality. Then, the adhesion of top diamond coatings were estimated using Rockwell C indentation analysis, revealing that the adhesion of top diamond coatings on the WC-6%Co substrates can be improved by the interlayers with the diamond/β-SiC composite structures. Comprehensive TEM interfacial analysis exhibits that the cobalt diffusion is weak from WC-6%Co substrate to the composite interlayer. The homogeneous microcrystalline diamond coatings with the most excellent adhesion can be fabricated on the substrates with the composite interlayer with the β-SiC/diamond ratio of about 45%. The composite structures are appropriate for the application in high-efficiency mechanical tool as a buffer layer for the deposition of the diamond coating.

Facile microwave approach towards high performance MoS2/graphene nanocomposite for hydrogen evolution reaction

Low-cost, highly efficient catalysts for hydrogen evolution reaction(HER) are very important to advance energy economy based on clean hydrogen gas. Intensive studies on two-dimensional molybdenum disulfides(2 D Mo S2) have been conducted due to their remarkable catalytic properties.However, most of the reported syntheses are time consuming,complicated and less efficient. The present work demonstrates the production of Mo S2/graphene catalyst via an ultra-fast(60 s) microwave-initiated approach. High specific surface area and conductivity of graphene delivers a favorable conductive network for the growth of Mo S2 nanosheets, along with rapid charge transfer kinetics. As-produced Mo S2/graphene nanocomposites exhibit superior electrocatalytic activity for the HER in acidic medium, with a low onset potential of62 m V, high cathodic currents and a Tafel slope of43.3 m V/decade. Beyond excellent catalytic activity, Mo S2/graphene reveals long cycling stability with a very high cathodic current density of around 1000 m A cm^-2 at an overpotential of 250 m V. Moreover, the Mo S2/graphene-catalyst exhibits outstanding HER activities in a temperature range of 30 to 120°C with low activation energy of36.51 k J mol^-1, providing the opportunity of practical scalable processing.

Effect of disconnector and high-voltage conductor on propagation characteristics of PD-induced UHF signals

UHF(ultra high frequency)method has been widely used in PD(partial discharge)detection for its high sensitivity.The resonance,distortion,and attenuation appearing in the propagation process of UHF signals in GIS(gas insulated switchgear)will influence the real situation of PD detection.Therefore,it is necessary to investigate the effect of GIS components such as disconnectors or high voltage conductors on the propagation characteristics of PD-induced UHF signals in various voltage classes GIS.The factors of PD signals propagation characteristics in axial and radial directions are both analysed to avoid the effect caused by placement of sensor in this paper.First,the simulation models of GIS are built based on FDTD(finite difference time domain)method.Then the propagation characteristics of PD-induced UHF signals are studied in the GIS with different disconnector gap lengths and different high voltage conductor radii.Finally,the reliability of the simulation results is verified by compared with laboratory tests.The disconnector gap and the change of conductor radii can both result in the signals attenuation which rises highest in the direction of 180°.The lower the GIS class voltage is,the larger the attenuation of signals after passing through disconnector gap is.

“蛋黄蛋壳”结构纳米电极材料设计及在锂/钠离子/锂硫电池中的应用

“蛋黄蛋壳”结构纳米材料,具有易于调控的“蛋黄”、“蛋壳”和“空腔”结构,可视作“纳米反应器”,在催化、储能等领域表现出显著的应用潜力。尤其在电化学能源存储和转换方面,该结构纳米电极具有大的比表面积和独特的核壳结构,在充放电过程中可缓解电极的体积变化,提供快速的离子/电子输运通道,强化中间产物的吸附和提升转换反应效率等,能显著提高电极稳定性、倍率性能和循环性能,是一类较为理想的电极材料。本文针对“蛋黄蛋壳”结构纳米电极在锂/钠离子电池、锂硫电池等新兴二次电池领域的实际应用,总结了具有该结构纳米电极的设计与合成策略,包括:模板法、奥斯特瓦尔德熟化、电化学置换、克肯达尔效应等,评述了各种策略的优缺点以及电极材料的应用进展,最后对该类材料在锂/钠体系及锂硫电池二次电池方面的研究与应用前景进行了展望。

Multifactor roadmap for designing low-power-consumed micro thermoelectric thermostats in a closed-loop integrated 5G optical module

As the core components of fifth-generation(5G)communication technology,optical modules should be consistently miniaturized in size while improving their level of integration.This inevitably leads to a dramatic spike in power consumption and a consequent increase in heat flow density when operating in a confined space.To ensure a successful start-up and operation of 5G optical modules,active cooling and precise temperature control via the Peltier effect in confined space is essential yet challenging.In this work,p-type Bi_(0.5)Sb_(1.5)Te_(3)and n-type Bi_(2)Te_(2.7)Se_(0.3)bulk thermoelectric(TE)materials are used,and a micro thermoelectric thermostat(micro-TET)(device size,2×9.3×1.1mm^(3);leg size,0.4×0.4×0.5mm^(3);number of legs,44)is successfully integrated into a 5G optical module with Quad Small Form Pluggable 28 interface.As a result,the internal temperature of this kind of optical module is always maintained at 45.7℃ and the optical power is up to 7.4 dBm.Furthermore,a multifactor design roadmap is created based on a 3D numerical model using the ANSYS finite element method,taking into account the number of legs(N),leg width(W),leg length(L),filling atmosphere,electric contact resistance(Rec),thermal contact resistance(Rtc),ambient temperature(Ta),and the heat generated by the laser source(QL).It facilitates the integrated fabrication of micro-TET,and shows the way to enhance packaging and performance under different operating conditions.According to the roadmap,the micro-TET(2×9.3×1mm^(3),W=0.3 mm,L=0.4 mm,N=68 legs)is fabricated and consumes only 0.89W in cooling mode(Q_(L)=0.7W,T_(a)=80℃)and 0.36Win heating mode(T_(a)=0℃)to maintain the laser temperature of 50℃.This research will hopefully be applied to other microprocessors for precise temperature control and integrated manufacturing.