Electron-deficient ZnO induced by heterointerface engineering as the dominant active component to boost CO_(2)-to-formate conversion

Electrocatalytic CO_(2)-to-formate conversion is considered an economically viable process.In general,Zn-based nanomaterials are well-known to be highly efficient electrocatalysts for the conversion of CO_(2) to CO,but seldom do they exhibit excellent selectivity toward formate.In this article,we demonstrate that a heterointerface catalyst ZnO/ZnSnO3 with nanosheet morphology shows enhanced selectivity with a maximum Faradaic efficiency(FE)of 86%at−0.9 V versus reversible hydrogen electrode and larger current density for the conversion of CO_(2) to formate than pristine ZnO and ZnSnO3.In particular,the FEs of the C1 products(CO+HCOO−)exceed 98%over the potential window.The experimental measurements combined with theoretical calculations revealed that the ZnO in ZnO/ZnSnO3 heterojunction delivers the valence electron depletion and accordingly optimizes Zn d-band center,which results in moderate Zn-O hybridization of HCOO*and weakened Zn-C hybridization of competing COOH*,thus greatly boosting the HCOOH generation.Our study highlights the importance of charge redistribution in catalysts on the selectivity of electrochemical CO_(2) reduction.

基于外观性状及内在成分的龙胆药材等级划分

目的为龙胆药材商品规格等级标准的制订提供科学依据。方法收集不同产地龙胆药材样品45批,对其外观性状药材长度、须根数、直径和色度进行测量,并测定龙胆药材水溶性浸出物、龙胆苦苷、马钱苷酸和獐牙菜苦苷的含量;采用SPSS 21.0软件分析龙胆内在成分与其外观性状的相关性,结合内外指标,建立龙胆药材的质量等级划分标准。结果通过相关性分析,龙胆药材外观性状与内在成分成正相关,药材长度越长、须根数越多、直径越大、颜色越浅,其浸出物、龙胆苦苷、马钱苷酸和獐牙菜苦苷含量就越高。经K-均值聚类分析,45批龙胆药材样品均划分为两个等级。结论该等级评价标准综合运用了外观性状、内在成分等多项指标,具有科学性、全面性等特点,对于建立龙胆药材商品等级标准有科学指导意义。

Track Tension Analysis of Four-Wheel Drive Tracked Vehicles

The distribution of track tension on track link is complex when the tracked vehicles run at a high speed.A multi-drive track link structure,which changes the traditional induction wheel into the driving wheel was proposed.The mathematical model of the system was established and the distribution of track tension was studied.The combined simulation model of RecurDyn and Simulink of the structure with multi-drive track was established.The simulation results show that our proposed structure has more uniform tension distribution than traditional structures,especially under the high speed condition.The maximum tension can be reduced by 28 kN-36 kN and the transmission efficiency can be improved by10%-16% under high speed condition with this new structure.

Wet-chemical synthesis and applications of amorphous metalcontaining nanomaterials

In the past decades,metal-containing nanomaterials have attracted increasing interests owing to their intriguing physicochemical properties and various promising applications.Recent research has revealed that the phase of metal-containing nanomaterials could significantly affect their properties and functions.In particular,nanomaterials with amorphous phase,which possess long-range disordered atomic arrangements,and the amorphous/crystalline heterophase nanostructures comprised of both amorphous and crystalline phases,have exhibited superior performance in various applications,e.g.,catalysis and energy storage.In this review,a brief overview of the recent progress on the wet-chemical synthesis and applications of amorphous and amorphous/crystalline heterophase metal-containing nanomaterials has been provided.Subsequently,on the basis of different categories of metal-containing nanomaterials,including metals,metal alloys,and metal compounds,their synthetic routes and promising applications will be highlighted.Finally,current challenges and some personal perspectives in this emerging research field will be proposed.

Stability evaluation of the PROSPECT model for leaf chlorophyll content retrieval

The radiative transfer model,PROSPECT,has been widely applied for retrieving leaf biochemical traits.However,little work has been conducted to evaluate the stability of the PROSPECT model with consideration of multiple factors(i.e.,spectral resolution,signal-to-noise ratio,plant growth stages,and treatments).This study aims to investigate the stability of the PROSPECT model for retrieving leaf chlorophyll(Chl)content(Cab).Leaf hemispherical reflectance and transmittance of oilseed rape were acquired at different spectral resolutions,noise levels,growth stages,and nitrogen treatments.The Chl content was also measured destructively by using a microplate spectrophotometer.The performance of the PROSPECT model was compared with a commonly used random forest(RF)model.The results showed that the prediction accuracy of PROSPECT and RF models for Cab did not produce significant differences under varied spectral resolutions ranging from 1 to 20 nm.The ranges of the relative root mean square errors(rRMSE)of the PROSPECT and RF models were 12%-13%and 11.70%-12.86%,respectively.However,the performance of both models for leaf Chl retrieval was strongly influenced by the noise level with the rRMSE of 13-15.37%and 12.04%-15.80%for PROSPECT and RF,respectively.For different growth stages,the PROSPECT model had similar prediction accuracies(rRMSE=9.26%-12.41%)to the RF model(rRMSE=9.17%-12.70%).Furthermore,the superiority of the PROSPECT model(rRMSE=10.10%-12.82%)over the RF model(rRMSE=11.81%-15.47%)was prominently observed when tested with plants growth at different nitrogen treatment levels.The results demonstrated that the PROSPECT model has a more stable performance than the RF model for all datasets in this study.

Enriching the library of axial superlattice nanowires

Integrating functional materials to form heterostructures with novel,sophisticated architectures has attracted extensive interest in chemistry and materials science^([1]).Heterostructures are expected to exhibit superior electrical,thermal,optical and magnetic properties due to the synergistic effect of their different components.Therefore,the rational design and preparation of heterostructures with controlled compositions,dimensions.

China's battery electric vehicles lead the world:achievements in technology system architecture and technological breakthroughs

Developing new energy vehicles has been a worldwide consensus,and developing new energy vehicles characterized by pure electric drive has been China's national strategy.After more than 20 years of high-quality development of China's electric vehicles(EVs),a technological R&D layout of“Three Verticals and Three Horizontals”has been created,and technological advantages have been accumulated.As a result,China's new energy vehicle market has ranked first in the world since 2015.To systematically solve the key problems of battery electric vehicles(BEVs)such as“driving range anxiety,long battery charging time,and driving safety hazards”,China took the lead in putting forward a“system engineering-based technology system architecture for BEVs”and clarifying its connotation.This paper analyzes the research status and progress of the three core components of this architecture,namely,“BEV platform,charging/swapping station,and real-time operation monitoring platform”,and their key technological points.The three major demonstration projects of the 2008 Beijing Olympic Games,the 2022 Beijing Winter Olympics,and the intelligent and connected autonomous battery electric bus project are discussed to specify the applications of BEVs in China.The key research directions for upgrading BEV technologies remain to be further improving the vehicle-level all-climate environmental adaptability and all-day safety of BEVs,systematically solving the charging problem of BEVs and improving their application convenience,and safeguarding safety with early warning and implementing active/passive safety protection for the whole life cycle of power batteries on the basis of BEVs'operation big data.BEVs have acquired new technological features such as intelligent and networked technology empowerment,extensive integration of control-by-wire systems,a platform of chassis hardware,and modularization of functional software.