Polarizable Additive with Intermediate Chelation Strength for Stable Aqueous Zinc‑Ion Batteries

Aqueous zinc-ion batteries are promising due to inherent safety,low cost,low toxicity,and high volumetric capacity.However,issues of dendrites and side reactions between zinc metal anode and the electrolyte need to be solved for extended storage and cycle life.Here,we proposed that an electrolyte additive with an intermediate chelation strength of zinc ion—strong enough to exclude water molecules from the zinc metal-electrolyte interface and not too strong to cause a significant energy barrier for zinc ion dissociation—can benefit the electrochemical stability by suppressing hydrogen evolution reaction,overpotential growth,and den-drite formation.Penta-sodium diethylene-triaminepentaacetic acid salt was selected for such a purpose.It has a suitable chelating ability in aqueous solutions to adjust solvation sheath and can be readily polarized under electrical loading conditions to further improve the passivation.Zn||Zn symmetric cells can be stably operated over 3500 h at 1 mA cm^(-2).Zn||NH4V4O10 full cells with the additive show great cycling stability with 84.6%capacity retention after 500 cycles at 1 A g^(-1).Since the additive not only reduces H2 evolution and corrosion but also modifies Zn2+diffusion and deposition,highlyreversible Zn electrodes can be achieved as verified by the experimental results.Our work offers a practical approach to the logical design of reliable electrolytes for high-performance aqueous batteries.

Crustal stress field in Yunnan: implication for crust-mantle coupling

We applied the g CAP algorithm to determine 239 focal mechanism solutions 3：0≤MW≤ 6：0） with records of dense Chin Array stations deployed in Yunnan,and then inverted 686 focal mechanisms（including 447 previous results） for the regional crustal stress field with a damped linear inversion. The results indicate dominantly strike-slip environment in Yunnan as both the maximum（r1） and minimum（r3） principal stress axes are sub-horizontal. We further calculated the horizontal stress orientations（i.e., maximum and minimum horizontal compressive stress axes： S H and S h, respectively） accordingly and found an abrupt change near ＊26°N. To the north, S H aligns NW-SE to nearly E-W while S h aligns nearly N-S. In contrast, to the south, both S H and S h rotate laterally and show dominantly fan-shaped patterns. The minimum horizontal stress（i.e., maximum strain axis） S h rotates from NW-SE to the west of Tengchong volcano gradually to nearly E-W in west Yunnan, and further toNE-SW in the South China block in the east. The crustal strain field is consistent with the upper mantle strain field indicated by shear-wave splitting observations in Yunnan but not in other regions. Therefore, the crust and upper mantle in Yunnan are coupled and suffering vertically coherent pure-shear deformation in the lithosphere.

Awareness intervention for Beijing neurologists regarding secondary prevention of cerebral infarction/transient ischemia Cross-sectional investigation

BACKGROUND： Stroke prevention guidelines should be made available application to aid in uniformity, timing, preciseness, and acceptance of disease. OBJECTIVE： To investigate the awareness of neurologists in some Beijing secondary prevention of cerebral infarction/transient ischemia. DESIGN： Cross-sectional study. to neurologists for clinical hospitals of intervention in SETTING： Beijing Tiantan Hospital, Beijing Anzhen Hospital, General Hospital of Beijing Military Area, Command of Chinese PLA, Beijing Chuiyangliu Hospital, Beijing 6^th Hospital, Beijing Hepingli Hospital, and Beijing Daxing District Hospital. PARTICIPANTS： A total of 28 （associate） chief physicians, 58 attending physicians, and 54 resident physicians who engaged in clinical treatment of cerebrovascular diseases were selected from 8 hospitals in Beijing from March to April 2007. All physicians provided informed consent. METHODS： Self-made closed questionnaires were provided for data collection, consisting of 16 questions that were single choice or multiple choice. Specifically, questions 1-7 focused on awareness of blood pressure regulation in different patients and first choice of decompression drug; questions 8-12 focused on awareness of lipid regulation; and questions 13-16 focused on awareness of anti-blood platelet drugs applied in secondary prevention. The scores ranged from 0-100 points, and each question was worth 6.25 points. The scores positively correlated with the awareness rate. To test leveling real-time, the survey lasted for a maximum of 20 minutes. One questionnaire was independently finished by each subject in the survey. MAIN OUTCOME MEASURES： Awareness intervention among neurologists during secondary prevention of cerebral infarction/transient ischemia and questionnaire scores. RESULTS： 140 subjects were included in the final analysis. ① The awareness rate among neurologists for intervention during secondary prevention of cerebral infarction/transient ischemia ranged from 0.7-57.9%, the scores ranged between 0-56 points, and the mean score was 26 points.② Scores of resident physicians were 0-56 points with a mean score of 26 points; attending physicians scored 6-50 points, with a mean score of 26 points; and chief physicians scored 6-50 points, with a mean score of 23 points. There were no significant differences among the various physicians （F = 0.771, t = 0.465, P 〉 0.05）. CONCLUSION： Awareness among neurologists of intervention during secondary prevention of cerebral infarction/transient ischemia is not ideal. However, there was no significant difference between professional titles.

通过接收函数和瑞利波联合反演揭示青藏高原东南缘两个壳内低速通道

目前解释青藏高原东缘的生长与扩张有诸多动力学模型,如:刚性块体挤出模型、连续变形和中下地壳流模型。由于受到岩石层结构模型分辨率的限制,青藏高原演化和变形的动力学过程仍不清楚。我们利用最新布设在青藏高原东南缘的地震台阵,通过接收函数和瑞利波联合反演得到了该区高分辨率三维岩石层横波速度模型,更好地揭示了壳内低速带(LVZ)分布特征。我们的速度模型显示研究区壳内存在两个低速通道,这两个低速通道边界与该区主要走滑断裂相对应,且沿着东喜马拉雅构造结顺时针分布,这与该区地壳物质顺时针运动模式比较一致。此外,我们观测到该区域主要大地震分布在这两个低速通道边界区域。据此,我们提出塑性流动和剪切变形在青藏高原的隆升和变形过程中都起了重要作用。

青藏高原东南缘远震S波分裂:对地壳上地幔复杂变形的启示

利用位于青藏高原东南缘云南地区的中国地震科学探测台站（C h in A ra y ）一期3 0 0 多个宽频带流动台站记录到的X K S 波形（包括SKS，S K K S， PKS）进行了 S 波分裂分析.X K S 分裂结果最主要的特征是快波偏振方向（φ） 在26-27°N 附近,从北部的近N -S 向突变为南部的近E-W 向.研究区西部喜马拉雅东构造结附近的结果较好地反映了岩石层左旋剪切变形下发育的各向异性.26°N 以南地区,快波分裂方向以E-W 向为主,与中上地壳最大张应力的方向一致,表明云南地区整个岩石层都可能处于纯剪切变形环境.但是该区岩石层厚度不足80k m ,产生的X K S 分裂快慢波时差（〈0.7s）仅能解释部分观测值（0.9-1.5s） .因此,软流层中的各向异性对于该地区的S 波分裂结果（快波偏振方向为N W -S E 和近E-W 向）可能产生了重要的作用.一方面,N W - S E 向快波偏振方向可能反映了缅甸块体的俯冲及其随后撤退引起的上地幔流动造成的各向异性.另一方面,伴随着高原构造演化发生的从青藏高原向中国东部的软流层物质流动,以及由于绝对板块运动造成的软流层顶部的剪切作用,将产生快波方向为近E-W 向的各向异性.本研究结果为研究青藏高原东南缘不同深度的变形特征及其差异提供了重要的信息,尤其在研究青藏高原的构造抬升及其向东南缘的扩展方面产生了新的认识.

扇面形散射元构建的二维光子晶体慢光模拟研究

本文用扇面形散射元构建空气孔型光子晶体模型,构建线缺陷波导,利用平面波展开法分别模拟其TM模式下的色散曲线,并通过改变散射元参数,求得群折射率、群速度、带宽、归一化延迟带宽积和色散常数,获得群折射率较大且带宽较大的理想模型。针对散射元,整体改变波导结构,分面对面型、背对背型和旋转30o三种,对其计算结果进行比较分析。

Fabrication of amorphous nanoporous ZrO_(2)/SiO_(2) aerogel enabling nonlinear optical properties

Amorphous oxides have unique physicochemical properties with extensive opto-electronic applications such as the thin-film transistor,light-emitting diode backplanes,and supercontinuum generation.In this contribution,we synthesize the amorphous ZrO_(2)/SiO_(2) nanoporous aerogel with high structural integrity.With the femtosecond excitation laser at 800–1,064 nm,the broadband second harmonic generation is observed.The nonlinear optical properties of the as-prepared ZrO_(2)/SiO_(2) aerogel are investigated at 1.0μm and 1.5μm for the first time.Subsequently,the amorphous ZrO_(2)/SiO_(2) saturable absorber is originally applied in the Yb-doped and Er-doped fiber lasers to realize the mode-locking operations.In the Yb-doped fiber laser,the dissipative soliton resonance mode-locking operation is demonstrated with the largest pulse duration of 22 ns at a repetition rate of 7.8 MHz and a high signal-to-noise ratio of 64 dB.In the Er-doped fiber laser,a conventional soliton mod-locking regime is observed with an ultrashort pulse width of 960 fs,a repetition frequency of 6.55 MHz,and a time-bandwidth production of 0.347.Our work shows the good ability of the ZrO_(2)/SiO_(2) aerogel in generating ultrafast pulses and extends the saturable absorber into the amorphous material realm.

Enhanced catalytic activity and thermal stability by highly dispersed Pd-based nanocatalysts embedded in ZrO_(2)hollow spheres

Sintering resistant noble metal nanoparticles are critical to the development of advanced catalysts with high activity and stability.Herein,we reported the construction of highly dispersed Pd nanoparticles loaded at the inner wall of ZrO_(2)hollow spheres(Pd@HS-ZrO_(2)),which shows improved activity and thermal stability over references in the Pd-ZrO_(2)(catalyst-support)system.Even after 800℃ high temperature calcination,the Pd nanoparticles and ZrO_(2)hollow spheres did not undergo morphological changes.The Pd@HS-ZrO_(2)manifests batter catalytic activity and thermal stability than the counterpart Pd/ZrO_(2)catalysts.In comparison to Pd/ZrO_(2)-800,Pd@ZrO_(2)-800 exhibits a 25℃ reduction in the temperature required for complete conversion of CO.The enhanced catalytic activity and thermal stability of Pd@HS-ZrO_(2)can be attributed to the nanoconfinement effect offered by the 10 nm wall thickness of the ZrO_(2)hollow spheres,which suppresses the coarsening of the Pd nanoparticles(active center for catalysis).

Intimate atomic Cu-Ag interfaces for high CO2RR selectivity towards CH4 at low over potential

Developing highly efficient electrochemical catalysts for carbon dioxide reduction reaction(CO_(2)RR)provides a solution to battle global warming issues resulting from ever-increasing carbon footprint due to human activities.Copper(Cu)is known for its efficiency in CO_(2)RR towards value-added hydrocarbons;hence its unique structural properties along with various Cu alloys have been extensively explored in the past decade.Here,we demonstrate a two-step approach to achieve intimate atomic Cu-Ag interfaces on the surface of Cu nanowires,which show greatly improved CO_(2)RR selectivity towards methane(CH4).The specially designed Cu-Ag interfaces showed an impressive maximum Faradaic efficiency(FE)of 72%towards CH4 production at-1.17 V(vs.reversible hydrogen electrode(RHE)).

Boosting the activity of Fe–N_x moieties in Fe–N–C electrocatalysts via phosphorus doping for oxygen reduction reaction

The Fe–N–C material is a promising non-noblemetal electrocatalyst for oxygen reduction reaction(ORR).Further improvement on the ORR activity is highly desired in order to replace Pt/C in acidic media.Herein,we developed a new-type of single-atom Fe–N–C electrocatalyst,in which Fe–Nxactive sites were modified by P atoms.The half-wave potential of the optimized material reached 0.858 V,which is 23 mV higher than that of the pristine one in a 0.1 mol L-1 HClO4 solution.Density functional theory(DFT)calculations revealed that P-doping can reduce the thermodynamic overpotential of the rate determining step and consequently improve the ORR activity.

Grazing alters environmental control mechanisms of evapotranspiration in an alpine meadow of the tibetan Plateau

Aims Evapotranspiration(Et)is an important component of the terrestrial water cycle and is easily affected by external disturbances,such as climate change and grazing.Identifying Et responses to grazing is instructive for determining grazing activity and informative for understanding the water cycle.Methods this study utilized 2 years(2014 and 2017)of eddy covariance data to test how grazing regulated Et for an alpine meadow ecosystem on the tibetan Plateau(tP)by path analysis.Important Findings Radiation dominated Et with a decision coefficient of 64-74%.the soil water content(SWc)worked as the limiting factor in the fenced site.However,in the grazing site,the limiting factor was the vapor pressure deficit(VPD).Grazing had large effects on Et because it greatly affected the water conditions.the SWc and VPD were enhanced by 14.63%and 4.36%in the grazing site,respectively.therefore,sufficient water was supplied to Et,especially during drought,and strengthened the transpiration pull.As a result,a favorable micrometeorological environment was created for Et.Grazing shifted the limiting factor of Et from the SWc to VPD,which weakened the limiting effect of the water conditions on Et and advanced the Et peak time.In addition,grazing altered the compositions of Et by changing the community structure,which directly resulted in an increased Et.In summary,grazing enhanced Et through altering the community structure and micrometeorological environments.the findings of this study further improve our understanding of the driving mechanisms of grazing on Et and will improve our predictions for the global water cycle.

1D PtCo nanowires as catalysts for PEMFCs with low Pt loading

The high cost of platinum(Pt)-group metal(PGM)-based catalysts used in proton-exchange membrane fuel cells(PEMFCs)poses a critical roadblock to their widespread adoption.Although using low PGM loading PEMFCs can largely address this challenge,high current density performance will be severely compromised consequently.To overcome this dilemma,we report the development of ultrathin platinum-cobalt nanowires(PtCoNWs)as the cathode catalysts for ultralow Pt loading and high-performance membrane electrode assembly(MEA).The Pt Co NWs delivered a record-high mass activity(MA)of 1.06±0.14 A mg_(Pt)^(-1) of Pt-alloy catalysts towards oxygen reduction reaction(ORR)in MEA,yielding an impressive total Pt utilization of 5.14 W_(rate)mg_(Pt)^(-1).The PtCoNWs retained a respectable endof-life MA of 0.45 Amg_(Pt)^(-1) after the 30,000 cycles square-wave accelerated stability test,which is still above the Department of Energy 2020 beginning-of-life target for catalysts.In-situ Xray absorption spectroscopy studies suggest that the high degree of alloying in the Pt Co NWs stabilizes the ultrathin structure and may contribute to the high ORR activity and power density performance in PEMFC.

Lagged climatic effects on carbon fluxes over three grassland ecosystems in China

Aims The plasticity of ecosystem responses could buffer and post-pone the effects of climates on ecosystem carbon fluxes,but this lagged effect is often ignored.In this study,we used carbon flux data collected from three typical grassland ecosystems in China,including a temperate semiarid steppe in Inner mongolia(Neimeng site,Nm),an alpine shrub-meadow in Qinghai(Haibei site,Hb)and an alpine meadow steppe in Tibet(Dangxiong site,DX),to examine the time lagged effects of environmental factors on CO_(2) exchange.Methods Eddy covariance data were collected from three typical Chinese grasslands.In linking carbon fluxes with climatic factors,we used their averages or cumulative values within each 12-month period and we called them‘yearly’statistics in this study.To investigate the lagged effects of the climatic factors on the car-bon fluxes,the climatic‘yearly’statistics were kept still and the‘yearly’statistics of the carbon fluxes were shifted backward 1 month at a time.Important Findingssoil moisture and precipitation was the main factor driving the annual variations of carbon fluxes at the alpine Hb and DX,respectively,while the Nm site was under a synthetic impact of each climatic factor.The time lagged effect analysis showed that temperature had several months,even half a year lag effects on Co2 exchange at the three studied sites,while moisture’s effects were mostly exhibited as an immediate manner,except at Nm.In general,the lagged climatic effects were relatively weak for the alpine ecosystem.our results implied that it might be months or even 1 year before the variations of ecosystem carbon fluxes are adjusted to the current climate,so such lag effects could be resistant to more frequent climate extremes and should be a critical component to be considered in evaluating ecosystem stability.an improved knowledge on the lag effects could advance our understanding on the driving mechanisms of climate change effects on ecosystem carbon fluxes.

Single-Atom Nanozymes Linked Immunosorbent Assay for Sensitive Detection of Aβ1-40:A Biomarker of Alzheimer’s Disease

Single-atom nanozymes(SANs)possess unique features of maximum atomic utilization and present highly assembled enzyme-like structure and remarkable enzyme-like activity.By introducing SANs into immunoassay,limitations of ELISA such as low stability of horseradish peroxidase(HRP)can be well addressed,thereby improving the performance of the immunoassays.In this work,we have developed novel Fe-N-C single-atom nanozymes(Fe-N_(x)SANs)derived from Fe-doped polypyrrole(PPy)nanotube and substituted the enzymes in ELISA kit for enhancing the detection sensitivity of amyloid beta 1-40.Results indicate that the Fe-N_(x)SANs contain high density of single-atom active sites and comparable enzyme-like properties as HRP,owing to the maximized utilization of Fe atoms and their abundant active sites,which could mimic natural metalloproteases structures.Further designed SAN-linked immunosorbent assay(SAN-LISA)demonstrates the ultralow limit of detection(LOD)of 0.88 pg/mL,much more sensitive than that of commercial ELISA(9.98 pg/mL).The results confirm that the Fe-N_(x)SANs can serve as a satisfactory replacement of enzyme labels,which show great potential as an ultrasensitive colorimetric immunoassay.

Variability in evapotranspiration shifts from meteorological to biological control under wet versus drought conditions in an alpine meadow

The Tibetan Plateau is generally referred to as the Chinese water tower,and evapotranspiration(ET)affects the water budget and stability of alpine meadows on the Tibetan Plateau.However,its variability and controlling mechanisms have not been well documented under the drier conditions induced by global warming.Therefore,this study aimed to clarify whether meteorological or biological factors primarily affected the variability in ET under contrasting water conditions in the alpine meadow ecosystem on the Tibetan Plateau.Based on 6-year(2013-2018)eddy covariance observations and the corresponding meteorological and biological data,linear perturbation analyses were employed to isolate the contributions of meteorological and biological factors to the variability in evapotranspiration(SET).The results showed that ET was mainly driven by meteorological factors in wet peak seasons(July and August),and was dominated by net radiation(Rn)and air temperature(Ta),indicating that the inadequate available energy is the factor limiting ET.However,the dominant factors affecting SET shifted from meteorological to biological in dry peak seasons when the canopy stomatal conductance(gs)and leaf area index were dominant.At this point,the ecosystem was limited by the water conditions.These results provide empirical insights into how meteorological and biological factors regulate variability in ET under contrasting water conditions.These findings can further improve our understanding of water cycle processes and can help effectively manage water resources in alpine meadow ecosystems under future climate change conditions.

Tubes with coated and sintered porous surface for highly efficient heat exchangers

Surface modification is a direct and effective way to enhance the efficiency of heat exchangers. Surface modification by forming a microporous coated layer can greatly enhance the boiling heat transfer and thus achieve a high performance. In this paper, we systematically investigate the boiling behavior on a plain surface with/ without sintered microporous coatings of copper powder. The results demonstrated that the sintered surface has a better performance in nucleate boiling due to the increased nucleation sites. The superheat degree is lower and the bubble departure diameter is larger for the sintered surface than for the plain surface, so the heat can be carried away more efficiently on the sintered surface. In addition, the heat transfer capacity on the sintered surface depends on both the powder size and the coating thickness for a high flux tube. The optimum heat transfer capacity can be obtained when the thickness of the microporous coating layer is 3-5 times of the sintered powder diameter. As a result, the heat transfer coefficient tube can be up to 3 times higher for the tube with a sintered surface than that with a plain surface, showing a pronounced enhancement in heat transfer and a high potential in chemical engineering industry application.

Influences of drought on the stability of an alpine meadow ecosystem

Drought plays a prominent role in affecting ecosystem stability and ecosystem productivity.Based on eddy covariance and climatic observations during 2012-2020,the Fisher discriminant analysis method was employed to accurately detect drought occurrences.Furthermore,the ecosystem water sensitivity and its resistance to drought were quantified to evaluate the ecosystem stability.The results showed that the alpine meadow suffered drought most frequently at the beginning of the growing seasons.However,drought during the peak growing seasons reduced the gross primary productivity(GPP)the most,by 30.5±15.2%.In the middle of the peak growing seasons,the ecosystem water sensitivity was weak,and thus,the resistance to drought was strong,which resulted in high ecosystem stability.At the beginning and end of the peak growing seasons,the ecosystem stability was relatively weak.Ecosystem stability was positively related to the corresponding multiyear average soil water content(SWC_(ave)).However,drought occurring during high SWC_(ave)periods led to larger reductions in GPP,which indicated that the inhibitory effects of drought on ecosystems were more dependent on the occurrence time of droughts than on ecosystem stability.

ELAID:detecting integer-Overflow-to-Buffer-Overflow vulnerabilities by light-weight and accurate static analysis

The Integer-Overflow-to-Buffer-Overflow(IO2BO)vulnerability has been widely exploited by attackers to cause severe damages to computer systems.Automatically identifying this kind of vulnerability is critical for software security.Despite many works have been done to mitigate integer overflow,existing tools either report large number of false positives or introduce unacceptable time consumption.To address this problem,in this article we present a static analysis framework.It first constructs an inter-procedural call graph and utilizes taint analysis to accurately identify potential IO2BO vulnerabilities.Then it uses a light-weight method to further filter out false positives.Specifically,it generates constraints representing the conditions under which a potential IO2BO vulnerability can be triggered,and feeds the constraints to SMT solver to decide their satisfiability.We have implemented a prototype system ELAID based on LLVM,and evaluated it on 228 programs of the NIST’s SAMATE Juliet test suite and 14 known IO2BO vulnerabilities in real world.The experiment results show that our system can effectively and efficiently detect all known IO2BO vulnerabilities.

Biotic effects dominate the inter-annual variability in ecosystem carbon exchange in a Tibetan alpine meadow

The alpine meadow ecosystem in Tibet is fragile and sensitive,and its carbon sink function with respect to climate change has become a matter of widespread concern.Therefore,this study aims to clarify the inter-annual variations(IAVs)in the carbon fluxes in an alpine meadow and to further quantify the contributions of the driving factors to the IAVs.Based on 7 years of flux data(2012-2018)and the corresponding climatic and biotic data,a set of look-up tables was used to separate and quantify the IAV sources.Furthermore,linear perturbation analyses were employed to quantify the contributions of each key factor.During 2012-2018,the net ecosystem productivity(NEP),gross primary productivity(GPP)and ecosystem respiration(Re)of this alpine meadow were 3.31±26.90,210.18±48.35 and 206.88±28.45 g C m^(-2) y^(-1),respectively,which indicated relatively large IAVs.When the contributions of climatic and biotic effects were distinguished and quantified,the dominant effects of biotic factors emerged.Additionally,negative interactions between climatic and biotic effects were detected.Among the climatic factors,only soil water content contributed relatively more to the IAVs and played a role in regulating the interactions between climatic and biotic effects.These results suggest that biotic effects must be carefully considered to reduce the uncertainties associated with future carbon flux estimates.

Fisher discriminant analysis method applied in drought detection:an instance in an alpine meadow ecosystem

Fisher discriminant analysis can comprehensively take multiple factors into consideration and effectively conduct separations between two classes.If it can be used to detect the occurrences of drought,drought can be detected more effectively and accurately.Based on 9-year carbon flux and corresponding meteorological data,soil water content(SWC)and vapor pressure deficit(VPD)were selected as the discriminant factors.Drought occurrences were detected by applying the Fisher discriminant analysis method in an alpine ecosystem in Tibet.Fisher discriminant analysis was successfully applied to detect drought occurrence in an alpine meadow ecosystem.The soil water deficit and atmospheric water deficit were comprehensively taken into consideration.Consequently,this method could detect the onset and end date of droughts more accurately and reasonably.Based on the characteristics of drought and non-drought samples,the discriminant equation was constructed as y=24.46SWC-4.60vPD.When y>1,the days were distributed above the critical line.In addition,when y was greater than one for more than 10 days,it was labeled as one drought event.If the interval between two drought processes was less than 2 days,it was considered one drought event.With increasing the study period and continued accumulation of observation data,the discriminant equation could be further optimized in the future,resulting in more accurate drought detection.