F-doped orthorhombic Nb_(2)O_(5) exposed with 97% (100) facet for fast reversible Liþ-Intercalation

Orthorhombic Nb_(2)O_(5)(T-Nb_(2)O_(5))is attractive for fast-charging Li-ion batteries,but it is still hard to realize rapid charge transfer kinetics for Li-ion storage.Herein,F-doped T-Nb_(2)O_(5) microflowers(F-Nb_(2)O_(5))are rationally synthesized through topotactic conversion.Specifically,F-Nb_(2)O_(5) are assembled by single-crystal nanoflakes with nearly 97%exposed(100)facet,which maximizes the exposure of the feasible Li^(+)transport pathways along loosely packed 4g atomic layers to the electrolytes,thus effectively enhancing the Li^(+)-intercalation performance.Besides,the band gap of F-Nb_(2)O_(5) is reduced to 2.87 eV due to the doping of F atoms,leading to enhanced electrical conductivity.The synergetic effects between tailored exposed crystal facets,F-doping,and ultrathin building blocks,speed up the Li^(+)/electron transfer kinetics and improve the pseudocapacitive properties of F-Nb_(2)O_(5).Therefore,F-Nb_(2)O_(5) exhibit superior rate capability(210.8 and 164.9 mAh g^(-1) at 1 and 10 C,respectively)and good long-term 10 C cycling performance(132.7 mAh g^(-1) after 1500 cycles).

Facile synthesis of the Mn_(3)O_(4)polyhedron grown on N-doped honeycomb carbon as high-performance negative material for lithium-ion batteries

Because of their large volume variation and inferior electrical conductivity,Mn_(3)O_(4)-based oxide anode materials have short cyclic lives and poor rate capability,which obstructs their development.In this study,we successfully prepared a Mn_(3)O_(4)/N-doped honeycomb carbon composite using a smart and facile synthetic method.The Mn_(3)O_(4)nanopolyhedra are grown on N-doped honeycomb carbon,which evidently mitigates the volume change in the charging and discharging processes but also improves the electrochemical reaction kinetics.More importantly,the Mn-O-C bond in the Mn_(3)O_(4)/N-doped honeycomb carbon composite benefits electrochemical reversibility.These features of the Mn_(3)O_(4)/N-doped honeycomb carbon(NHC)composite are responsible for its superior electrochemical performance.When used for Li-ion batteries,the Mn_(3)O_(4)/N-doped honeycomb carbon anode exhibits a high reversible capacity of 598 mAh·g^(−1)after 350 cycles at 1 A·g^(−1).Even at 2 A·g^(−1),the Mn_(3)O_(4)/NHC anode still delivers a high capacity of 472 mAh·g^(−1).This work provides a new prospect for synthesizing and developing manganese-based oxide materials for energy storage.

Dealloying of an amorphous TiCuRu alloy results in a nanostructured electrocatalyst for hydrogen evolution reaction

Development of an electrocatalyst that is cheap and has good properties to replace conventional noble metals is important for H_(2) applications.In this study,dealloying of an amorphous Ti_(37)Cu_(60)Ru_(3) alloy was performed to prepare a freestanding nanostructured hydrogen evolution reaction(HER)catalyst.The effect of dealloying and addition of Ru to TiCu alloys on the microstructure and HER properties under alkaline conditions was investigated.3 at.%Ru addition in Ti_(40)Cu_(60) decreases the overpotential to reach a current density of 10mA cm^(-2) and Tafel slope of the dealloyed samples to 35 and 34mV dec−1.The improvement of electrocatalytic properties was attributed to the formation of a nanostructure and the modification of the electronic structure of the catalyst.First-principles calculations based on density function theory indicate that Ru decreases the Gibbs free energy of water dissociation.This work presents a method to prepare an efficient electrocatalyst via dealloying of amorphous alloys.

Genetic diversity and population structure of Robinia pseudoacacia from six improved variety bases in China as revealed by simple sequence repeat markers

Robinia pseudoacacia is an important afforesta-tion tree introduced to China in 1878.In the present study,we examined the genetic diversity among 687 strains rep-resenting four improved varieties and two secondary prov-enances,comprising 641 clones and 46 seedlings.Ninety-one simple sequence repeats(SSRs)were selected through segregation analysis and polymorphism characterization,and all sampled individuals were genotyped using well-characterized SSR markers.After excluding loci with non-neutral equilibrium,missing locus data and null alleles,we used 36 primer pairs to assess the genetic diversity of these germplasm resources,revealing vast genetic differentiation among the samples,with an average of 8.352 alleles per locus and a mean Shannon′s index of 1.302.At the popula-tion level,the partitioning of variability was assessed using analysis of molecular variance,which revealed 93%and 7%variation within and among collection sites,respectively.Four clusters were detected using structure analysis,indi-cating a degree of genetic differentiation among the six populations.Insights into the genetic diversity and structure of R.pseudoacacia provide a theoretical basis for the con-servation,breeding and sustainable development in China.

Ammonia in urban atmosphere can be substantially reduced by vehicle emission control:A case study in Shanghai, China

To investigate the impact of emission controls on ammonia(NH_(3)) pollution in urban atmosphere, observation on NH_(3)(1 hr interval) was performed in Shanghai before, during and after the 2019 China International Import Expo (CIIE) event, along with measurements on inorganic ions, organic tracers and stable nitrogen isotope compositions of ammonium in PM_(2.5). NH_(3)during the CIIE period was 6.5±1.0μg/m^(3), which is 41% and 32% lower than that before and after the event, respectively. Such a decrease was largely ascribed to the emission controls in nonagricultural sources, of which contribution for measured NH_(3)in control phase abated by ~20% compared to that during uncontrol period. Molecular compositions of PAHs and hopanes further suggested a dominant role of the reduced vehicle emissions in the urban NH_(3)abatement during the CIIE period. Our results revealed that vehicle exhaust emission control is an effective way to mitigate NH_(3)pollution and improve air quality in Chinese urban areas.

Significant coal combustion contribution to water-soluble brown carbon during winter in Xingtai, China: Optical properties and sources

To understand the characteristics of atmospheric brown carbon(BrC),daily PM2.5 samples in Xingtai,a small city in North China Plain(NCP),during the four seasons of 2018-2019,were collected and analyzed for optical properties and chemical compositions.The light absorption at 365 nm(abs λ=365 nm)displayed a strong seasonal variation with the highest value in winter(29.0±14.3 M/m),which was 3.2∼5.4-fold of that in other seasons.A strong correlation of abs λ=365 nm with benzo(b)fluoranthene(BbF)was only observed in winter,indicating that coal combustion was the major source for BrC in the season due to the enhanced domestic heating.The mass absorbing efficiency of BrC also exhibited a similar seasonal pattern,and was found to correlate linearly with the aerosol pH,suggesting a positive effect of aerosol acidity on the optical properties and formation of BrC in the city.Positive matrix factorization(PMF)analysis further showed that on a yearly basis the major source for BrC was biomass burning,which accounted for 34% of the total BrC,followed by secondary formation(26.7%),coal combustion(21.3%)and fugitive dust(18%).However,the contribution from coal combustionwas remarkably enhanced in winter,accounting for∼40%of the total.Our work revealed that more efforts of“shifting coal to clean energy”are necessary in rural areas and small cities in NCP in order to further mitigate PM2.5 pollution in China.

Nanoparticles (NPs)-mediated Siglec15 silencing and macrophage repolarization for enhanced cancer immunotherapy

cell infiltration and proliferation in tumor tissues are the main factors that significantly affect the therapeutic outcomes of cancer immunotherapy.Emerging evidence has shown that interferon-gamma(IFN)could enhance CXCL9 secretion from macrophages to recruit T cells,but Siglec15 expressed on TAMs can attenuate T cell proliferation.Therefore,targeted regulation of macrophage function could be a promising strategy to enhance cancer immunotherapy via concurrently promoting the infiltration and proliferation of T cells in tumor tissues.We herein developed reductionresponsive nanoparticles(NPs)made with poly(disulfide amide)(PDSA)and lipid-poly(ethylene glycol)(lipid-PEG)for systemic delivery of Siglec15 siRNA(siSiglec15)and IFN for enhanced cancer immunotherapy.After intravenous administration,these cargo-loaded could highly accumulate in the tumor tissues and be efficiently internalized by tumor-associated macrophages(TAMs).With the highly concentrated glutathione(GSH)in the cytoplasm to destroy the nanostructure,the loaded IFN and si-Siglec15 could be rapidly released,which could respectively repolarize macrophage phenotype to enhance CXCL9 secretion for T cell infiltration and silence Siglec15 expression to promote T cell proliferation,leading to significant inhibition of hepatocellular carcinoma(HCC)growth when combining with the immune checkpoint inhibitor.The strategy developed herein could be used as an effective tool to enhance cancer immunotherapy.

Predicting community traits along an alpine grassland transect using field imaging spectroscopy

Assessing plant community traits is important for understanding how terrestrial ecosystems respond and adapt to global climate change.Field hyperspectral remote sensing is effective for quantitatively estimating vegetation properties in most terrestrial ecosystems,although it remains to be tested in areas with dwarf and sparse vegetation,such as the Tibetan Plateau.We measured canopy reflectance in the Tibetan Plateau using a handheld imaging spectrometer and conducted plant community investigations along an alpine grassland transect.We estimated community structural and functional traits,as well as community function based on a field survey and laboratory analysis using 14 spectral vegetation indices(VIs)derived from hyperspectral images.We quantified the contributions of environmental drivers,VIs,and community traits to community function by structural equation modelling(SEM).Univariate linear regression analysis showed that plant community traits are best predicted by the normalized difference vegetation index,enhanced vegetation index,and simple ratio.Structural equation modelling showed that VIs and community traits positively affected community function,whereas environmental drivers and specific leaf area had the opposite effect.Additionally,VIs integrated with environmental drivers were indirectly linked to community function by characterizing the variations in community structural and functional traits.This study demonstrates that community-level spectral reflectance will help scale plant trait information measured at the leaf level to larger-scale ecological processes.Field imaging spectroscopy represents a promising tool to predict the responses of alpine grassland communities to climate change.

A generative deep learning framework for inverse design of compositionally complex bulk metallic glasses

The design of bulk metallic glasses(BMGs)via machine learning(ML)has been a topic of active research recently.However,the prior ML models were mostly built upon supervised learning algorithms with human inputs to navigate the high dimensional compositional space,which becomes inefficient with the increasing compositional complexity in BMGs.Here,we develop a generative deep-learning framework to directly generate compositionally complex BMGs,such as high entropy BMGs.Our framework is built on the unsupervised Generative Adversarial Network(GAN)algorithm for data generation and the supervised Boosted Trees algorithm for data evaluation.We studied systematically the confounding effect of various data descriptors and the literature data on the effectiveness of our framework both numerically and experimentally.Most importantly,we demonstrate that our generative deep learning framework is capable of producing composition-property mappings,therefore paving the way for the inverse design of BMGs.

脱落酸对丛枝菌根真菌侵染和产孢的调控效应研究

【目的】揭示脱落酸(ABA)对丛枝菌根(AM)真菌侵染和产孢的影响,建立利用外源ABA促进孢子产量的高效菌剂扩繁方法。【方法】利用番茄毛状根和AM真菌Rhizophagus irregularis DAOM 197198建立双重培养体系,通过外源施用ABA、赤霉素(GA)或者使用ABA、GA的缺陷突变体,染色观察菌根侵染,荧光定量PCR测定丛枝发育和脂质合成运输相关基因的表达,统计丛枝和孢子的数量,从而揭示ABA对AM真菌侵染和产孢的影响。【结果】ABA缺陷突变体not中的F%(侵染频率)、a%(丛枝丰度)、丛枝数量,以及丛枝发育特异性相关基因EXO70A1-like(LOC101253481)、脂质合成运输相关基因RAM2和STR2的表达均显著低于其野生型MT;外源施用ABA显著促进了F%、M%(侵染强度)、丛枝数量、孢子产量,以及脂质合成运输相关基因RAM2和STR2的表达,外源添加ABA处理的孢子产量约为不添加处理的4.5倍;外源GA处理极显著抑制了菌根侵染的所有指标和孢子产量;GA缺陷突变体gib3与其野生型MM的AM真菌侵染之间没有显著差异,但gib3的孢子产量显著高于MM。【结论】ABA通过促进脂质的合成和运输,提高AM真菌的侵染和丛枝形成,进而增加AM真菌的孢子产量。

Effects of Annealing Below Glass Transition Temperature on the Wettability and Corrosion Performance of Fe-based Amorphous Coatings

This study investigated the effect of annealing below glass transition temperature(T_(g))on the microstructural characteristics,mechanical property,wettability,and electrochemical performance of activated combustion-high velocity air fuel(AC-HVAF)-sprayed Fe-Cr-Mo-W-C-B-Y amorphous coatings(ACs).Results showed that Fe-based ACs with a thickness of~300μm exhibited a fully amorphous structure with low oxidization.Originating from the reduced free volume,sub-T_(g) annealing increased the thermal stability,hardness,and surface hydrophobicity of Fe-based ACs.The enhanced corrosion resistance of sub-T_(g) annealed ACs in 3.5 wt%NaCl solution was attributed to the increased surface hydrophobicity and passivation capability.This finding elucidates the correlation between sub-T_(g) annealing and the properties of Fe-based ACs,which promotes ameliorating ACs with superior performance.

Machine learning atomic dynamics to unfold the origin of plasticity in metallic glasses:From thermo-to acousto-plastic flow

Metallic glasses(MGs)have an amorphous atomic arrangement,but their structure and dynamics in the nanoscale are not homogeneous.Numerous studies have confirmed that the static and dynamic heterogeneities of MGs are vital for their deformation mechanism.The“defects”in MGs are envisaged to be structurally loosely packed and dynamically active to external stimuli.To date,no definite structure-property relationship has been established to identify liquid-like“defects”in MGs.In this paper,we proposed a machine-learned“defects”from atomic trajectories rather than static structural signatures.We analyzed the atomic motion behavior at different temperatures via a k-nearest neighbors machine learning model,and quantified the dynamics of individual atoms as the machine-learned temperature.Applying this new temperature-like parameter to MGs under stress-induced flow,we can recognize which atoms respond like“liquids”to the applied loads.The evolution of liquid-like regions reveals the dynamic origin of plasticity(thermo-and acousto-plasticity)of MGs and the correlation between stress-induced heterogeneity and local environment around atoms,providing new insights into thermo-and acousto-plastic forming.

“Softness” as the structural origin of plasticity in disordered solids: a quantitative insight from machine learning

Disordered solids,including various types of glasses,such as metallic glasses (MGs),ceramic glasses and polymeric glasses,possess an amorphous or aperiodic arrangement of their building blocks,such as atoms,ions and molecules.At first sight,this is similar to the structure of their corresponding liquids,lacking any long-range translational symmetry as in crystalline solids.As a result,disordered solids usually exhibit a unique combination of properties,and are an indispensable class of engineering materials.For instance,MGs exhibit superb strength, high elastic limit,and outstanding corrosion-and wear- resistance,which is ideal for making sporting and medical apparatus.However,disordered solids,particularly structural glasses,could be very brittle under an ambient condition.Catastrophic failures can take place in them without noticeable plasticity [1,2].In practice,this severely hinders the applications of disordered solids as a reliable structural material;therefore,the origin of plas- ticity in disordered solids,if any,has been remaining in decades as one of the most active topics in materials science and engineering.

Effect of NOx and RH on the secondary organic aerosol formation from toluene photooxidation

The secondary organic aerosol(SOA)formation mechanism and physicochemical properties can highly be influenced by relative humidity(RH)and NOx concentration.In this study,we performed a laboratory investigation of the SOA formation from toluene/OH photooxidation system in the presence or absence of NOx in dry and wet conditions.The chemical composition of toluene-derived SOA was measured using Aerodyne high-resolution timeof-flight aerosol mass spectrometer(HR-ToF-AMS).It was found that the mass concentration of toluene decreased with increasing RH and NOx concentration.However,the change of SOA chemistry composition(f_(44),O/C)with increased RH was not consistent in the condition with or without NOx.The light absorption and mass absorption coefficient(MAC)of the toluene-derived SOA only increased with RH in the presence of NOx.In contrast,MAC is invariant with RH in the absence of NOx.HR-ToF-AMS results showed that,in the presence of NOx,the increased nitro-aromatic compounds and N/C ratio concurrently caused the increase of SOA light absorption and O/C in wet conditions,respectively.The relative intensity of CHON and CHOxN family to the total nitrogen-containing organic compounds(NOCs)increased with the increasing RH,and be the major components of NOCs in wet condition.This work revealed a synergy effect of NOx and RH on SOA formation from toluene photooxidation.

Heat treatment of hot-isostatic-pressed 60NiTi shape memory alloy:Microstructure,phase transformation and mechanical properties

60NiTi alloy is considered to be a promising material for specialized bearing and gear applications due to its high hardness,strength,and low modulus.However,fabricating 60NiTi through conventional processing methods is challenging due to the brittleness and poor workability.In this study,60NiTi with high relative density was successfully fabricated directly from pre-alloyed powder through hot isostatic pressing.The effects of solution and aging treatments on microstructure and mechanical properties were systematically studied by advanced characterization techniques.The hot-isostatic-pressed 60NiTi showed low average hardness and elastic strain due to the formation of a soft Ni_(3)Ti phase and B2 NiTi matrix.Solution treatment above 1000℃dissolved the Ni_(3)Ti phase and promoted the formation of nanoscale Ni_(4)Ti_(3)precipitates,which significantly improved the hardness,strength,and elastic strain of 60NiTi.The formation of the Ni_(4)Ti_(3) phase can be mainly attributed to the driving forces induced by the chemical supersaturation and mechanical stress concentration.Finally,the phase transformation mechanisms during heat treatment and compression test were discussed.

Bimetallic sulfide FeS_(2)@SnS_(2) as high-performance anodes for sodium-ion batteries

A novel hierarchical structure of bimetal sulfide FeS_(2)@SnS_(2) with the 1D/2D heterostructure was developed for high-performance sodium-ion batteries(SIBs).The FeS_(2)@SnS_(2) was synthesized through a hydrothermal reaction and a sulphuration process.The exquisite 1D/2D heterostructure is featured with 2D SnS_(2) nanoflakes anchoring on the 1D FeS2 nanorod.This well-designed FeS_(2)@SnS_(2) provides shortened ion diffusion pathway and adequate surface area,which facilitates the Na+transport and capacitive Na+storage.Besides,the FeS_(2)@SnS_(2) integrates the 1D/2D synthetic structural advantages and synthetic hybrid active material.Consequently,the FeS_(2)@SnS_(2) anode exhibits high initial specific capacity of 765.5 mAh·g^(-1) at 1 A·g^(-1) and outstanding reversibility(506.0 mAh·g^(-1) at 1 A·g^(-1) after 200 cycles,262.5 mAh·g^(-1) at 5 A·g^(-1) after 1400 cycles).Moreover,the kinetic analysis reveals that the FeS_(2)@SnS_(2) anode displays significant capacitive behavior which boosts the rate capacity.

A linear relationship between De Ritis ratio and mortality in hospitalized patients with COVID-19:A secondary analysis based on a large retrospective cohort study

Background and aims:Although some studies have identified a possible link between the De Ritis ratio and the mortality of patients with COVID-19),the predictive value and the optimal cut-value remain unclear.This study aimed to explore the correlation between the De Ritis ratio and mortality in hospitalized COVID-19.Methods:The data for this cohort study came from a retrospective cohort study that was carried out in a medical system in New York City.The primary outcome was the in-hospital mortality of included patients.The researchers ran multivariate Cox regression analyses,curve fitting,and subgroup analysis to support our findings.Overall survival in different De Ritis ratio groups was plotted as Kaplan-Meier survival curves.Results:The study enrolled 4371 participants with COVID-19 from March 1,2020 to April 16,2020.The overall mortality was 24.8%(1082/4371).The curve fitting analyses indicated that the De Ritis ratio has a positive linear connection with mortality in patients with COVID-19.After adjusting for all covariates,participants with a De Ritis ratio≥2 exhibited 1.29 times the risk of in-hospital mortality compared with those with a De Ritis ratio<1(hazard ratio 1.29,95%confidence interval 1.02-1.62,p=0.031).The p for trend was<0.05 for all models.Patients in the group with a De Ritis ratio≥2 experienced the shortest survival time in the Kaplan-Meier survival analysis.Conclusions:A higher baseline De Ritis ratio is correlated with a corresponding higher mortality among hospitalized people with COVID-19.