Direct insight into sulfiphilicity-lithiophilicity design of bifunctional heteroatom-doped graphene mediator toward durable Li-S batteries

The practical applications of lithium-sulfur(Li-S)battery have been greatly hindered by the severe polysulfide shuttle at the cathode and rampant lithium dendrite growth at the anode.One of the effective solutions deals with concurrent management of both electrodes.Nevertheless,this direction remains in a nascent stage due to a lack of material selection and mechanism exploration.Herein,we devise a temperature-mediated direct chemical vapor deposition strategy to realize the controllable synthesis of three-dimensional boron/nitrogen dual-doped graphene(BNG)particulated architectures,which is employed as a light-weighted and multi-functional mediator for both electrodes in Li-S batteries.Benefiting from the“sulfiphilic”and“lithiophilic”features,the BNG modified separator not only enables boosted kinetics of polysulfide transformation to mitigate the shuttle effect but also endows uniform lithium deposition to suppress the dendritic growth.Theoretical calculations in combination with electro-kinetic tests and operando Raman analysis further elucidate the favorable sulfur and lithium electrochemistry of BNG at a molecular level.This work offers direct insight into the mediator design via controllable synthesis of graphene materials to tackle the fundamental challenges of Li-S batteries.

A Natural Polymer Captor for Immobilizing Polysulfide/Polyselenide in Working Li-SeS_(2) Batteries

SeS_(2) has become a promising cathode material owing to its enhanced electrical conductivity over sulfur and higher theoretical specific capacity than selenium;however,the working Li-SeS_(2) batteries have to face the practical challenges from the severe shuttling of soluble dual intermediates of polysulfide and polyselenide,especially in high-SeS_(2)-loading cathodes.Herein,a natural organic polymer,Nicandra physaloides pectin(NPP),is proposed to serve as an effective polysulfide/polyselenide captor to address the shuttling issues.Informed by theoretical calculations,NPP is competent to provide a Lewis base-based strong binding interaction with polysulfides/polyselenides via forming lithium bonds,and it can be homogeneously deposited onto a three-dimensional double-carbon conductive scaffold to finally constitute a polysulfide/polyselenide-immobilizing interlayer.Operando spectroscopy analysis validates the enhanced polysulfide/polyselenide trapping and high conversion efficiency on the constructed interlayer,hence bestowing the Li-SeS_(2) cells with ultrahigh rate capability(448 mAh g^(−1)at 10 A g^(−1)),durable cycling lifespan(≈0.037%capacity attenuation rate per cycle),and high areal capacity(>6.5 mAh cm^(−2))at high SeS_(2) loading of 15.4 mg cm^(−2).Importantly,pouch cells assembled with this interlayer exhibit excellent flexibility,decent rate capability with relatively low electrolyte-to-capacity ratio,and stable cycling life even under a low electrolyte condition,promising a low-cost,viable design protocol toward practical Li-SeS_(2) batteries.

Application of UPLC-QTOF-MS Technology in Quality Stability Evaluation of Moluodan Concentrated Pills

[Objectives]To use liquid chromatography-mass spectrometry technology to analyze the chemical composition of traditional Chinese medicine and explore its application in the evaluation of quality stability of traditional Chinese medicine.[Methods]Ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry(UPLC-QTOF-MS)was used to detect the samples of Moluodan concentrated pills.By comparing and analyzing the detection results of 10 different batches of Moluodan concentrated pills,combined with principal component analysis(PCA),the quality stability of Moluodan concentrated pills was evaluated.[Results]A total of 367 chemical components were identified in Moluodan concentrated pills.The average repetition rate of the chemical components contained in the 10 different batches of samples reached 92%.The overall quality stability of the Moluodan concentrated pills was good.[Conclusions]The UPLC-QTOF-MS technology combined with PCA provides a reference for the overall quality evaluation of Moluodan concentrated pills,and provides new detection methods and ideas for the analysis of the components of Chinese medicine.

A multi-scale framework for life reduction assessment of turbine blade caused by microstructural degradation

The prolonged thermal exposure with centrifugal load results in microstructural degradation,which ultimately leads to a reduction in the fatigue and creep resistance of the turbine blades.The present work proposes a multi-scale framework to estimate the life reduction of turbine blades,which combines a microstructural degradation model,a two-phase constitutive model,and a microstructure-dependent fatigue and creep life reduction model.The framework with multi-scale models is validated by a Single Crystal(SC)Ni-based superalloy at the microstructural length-scale and is then applied to calculate the microstructural degradation and the fatigue and creep life reduction of turbine blades under two specific service conditions.The simulation results and quantitative analysis show that the microstructural degradation and fatigue and creep life reduction of the turbine blade are heavily influenced by the variations in the proportion of the intermediate state,namely,the maximum rotor speed status,in the two specific service conditions.The intermediate state accelerates the microstructural degradation and leads to a reduction of the life,especially the effective fatigue life reserve due to the higher temperature and rotational speed than that of the 93%maximum rotor speed status marked as the reference state.The proposed multi-scale framework provides a capable approach to analyze the reduction of the fatigue and creep life for turbine blade induced by microstructural degradation,which can assist to determine a reasonable Time Between Overhaul(TBO)of the engine.

A review in rational design of graphene toward advanced Li-S batteries

For lithium-sulfur(Li-S)batteries,the problems of polysulfides shuttle effect,slow dynamics of sulfur species and growth of lithium dendrite during charge/discharge processes have greatly impeded its practical development.Of core importance to advance the performances of Li-S batteries lies in the selection and design of novel materials with strong polysulfides adsorption ability and enhanced redox electrocatalytic behavior.Graphene,affording high electrical conductivity,superior carrier mobility,and large surface area,has presented great potentials in improving the performances of Li-S cells.However,the properties of intrinsic graphene are far enough to achieve the multiple management toward electrochemical catalysis of energy storage systems.In addition,a general and objective understanding of its role in Li-S systems is still lacking.Along this line,we summarize the design routes from three aspects,including defect engineering,dimension adjustment,and heterostructure modulation,to perfect the graphene properties.Thus-synthesized graphene materials are explored as multifunctional electrocatalysts targeting high-efficiency and long-lifespan Li-S batteries,based on which the regulating role of graphene is comprehensively analyzed.This project provides a perspective on the effective engineering management of graphene materials to boost Li-S chemistry,meanwhile promote the practical application process for graphene materials.

Genetic Polymorphism and Relationship Analyses of Standard Poodle and Bichon Frise Groups Based on 19 Short Tandem Repeat Loci

Context:As the increasing number of pet canines,the identification of canine has attracted much attentions in the forensic field,however,the genetic diversities of pet canines still remained unknown.Aims:To explore genetic polymorphisms of 19 short tandem repeat(STR)loci and genetic relationships between the two studied canine groups and reference group.Subjects and Methods:In the present study,genetic polymorphisms of 19 STR loci and a sex-linked zinc finger locus were analyzed in a total of 594 canines in Standard Poodle and Bichon Frise groups from China.Results:A total of 166,159 alleles were observed in the Standard Poodle,Bichon Frise groups with the corresponding allelic frequencies ranging from 0.0030-0.6108 to 0.0012-0.6148,respectively.The combined discrimination power and probability of exclusion of 19 STR loci in Standard Poodle and Bichon Frise groups were 0.9999999999999497,0.999962884;and 0.99999999999999995,0.999965955,respectively.Furthermore,the genetic distances between the two canine groups and Labrador retriever group were calculated,and the results indicated that Standard Poodle and Bichon Frise groups showed a closer genetic relationship,while the two canine groups had distant genetic relationships with Labrador retriever group.The result of population genetic structure revealed that genetic component distributions in the three canine groups were different.The predicted accuracies of the constructed random forest prediction model for three validation sets(25%individuals randomly selected from three populations with 808 individuals)were higher than 0.9,especially for the individuals in validation set from the Bichon Frise group is 1.Conclusions:The 19 STR loci could be used for individual identification,canine breed identification and paternity testing in the two canine groups.

Decorating Vertically Oriented Graphene Arrays with Co-Doped NiTe_(2)Toward Al-Current-Collector-Free Li-S Batteries

Lithium-sulfur(Li-S)batteries are broadly regarded as one of the most promising energy storage systems owing to their high-energy and low-cost features.Nevertheless,their practical implementation is plagued by the notorious polysulfide shuttling and sluggish reaction kinetics.Transition metal telluride has emerged as a promising electrocatalyst to expedite sulfur redox kinetics,even though its controllable and precise fabrication remains quite elusive.Herein,we propose the employment of a chemical vapor deposition approach to achieve in situ growth of Co-doped NiTe_(2)(Co-NiTe_(2))on vertically oriented graphene coated carbon cloth(VG/CC)substrate,in the pursuit of high-performance sulfur host material(Co-NiTe_(2)@VG/CC)in Li-S realms.Electrokinetic analysis and operando Raman spectroscopy characterization reveal the effective regulation capability of Co-NiTe_(2)@VG/CC with respect to polysulfide capture/conversion and Li2S decomposition.As a result,the Al-currentcollector-free Co-NiTe_(2)@VG/CC-based cathodes with typical sulfur loading exhibit outstanding cycling stability(93.8% capacity retention over 100 cycles at 0.5 C).Moreover,an areal capacity of 4.27 mAh cm^(-2) at 0.2 C can be harvested even at an elevated sulfur loading of 7.2 mg cm^(-2).

Precise synthesis of N-doped graphitic carbon via chemical vapor deposition to unravel the dopant functions on potassium storage toward practical K-ion batteries

Nitrogen doped carbon is a burgeoning anode candidate for potassium-ion battery(PIBs)owing to its outstanding attributes.It is imperative to grasp further insight into specific effects of different nitrogen dopants in carbon anode toward advanced K-ion storage.However,the prevailing fabrication method is plagued by the fact that considerable variations in the total N-doping concentration occur in the course of regulating the type of nitrogen dopants,incapable of distinguishing the certain roles of them under similar conditions.Herein,throughout the precise preparation of high edge-N doped carbon(HENC)and high graphitic-N doped carbon(HGNC)harnessing basically identical N-doping levels(5.78 at.%for HENC;5.07 at.%for HGNC)via chemical vapor deposition route,the effects of edge-N and graphitic-N in the carbon anode on K-ion storage are revisited,offering guidance into the design of low-cost and high-performance PIB systems.