Engineering single-atom Mn on nitrogen-doped carbon to regulate lithium-peroxide reaction kinetics for rechargeable lithium-oxygen batteries

Precision engineering of catalytic sites to guide more favorable pathways for Li_(2)O_(2) nucleation and decom-position represents an enticing kinetic strategy for mitigating overpotential,enhancing discharge capac-ity,and improving recycling stability of Li-O_(2) batteries.In this work,we employ metal-organic frameworks(MOFs)derivation and ion substitution strategies to construct atomically dispersed Mn-N_(4) moieties on hierarchical porous nitrogen-doped carbon(Mn SAs-NC)with the aim of reducing the over-potential and improving the cycling stability of Li-O_(2) batteries.The porous structure provides more chan-nels for mass transfer and exposes more highly active sites for electrocatalytic reactions,thus promoting the formation and decomposition of Li_(2)O_(2).The Li-O_(2) batteries with Mn SAs-NC cathode achieve lower overpotential,higher specific capacity(14290 mA h g^(-1) at 100 mAg^(-1)),and superior cycle stability(>100 cycles at 200 mA g^(-1))compared with the Mn NPs-NC and NC.Density functional theory(DFT)cal-culations reveal that the construction of Mn-N_(4) moiety tunes the charge distribution of the pyridinic N-rich vacancy and balances the affinity of the intermediates(LiO_(2) and Li_(2)O_(2)).The initial nucleation of Li_(2)O_(2) on Mn SAs-NC favors the O_(2)-→LiO_(2)→Li_(2)O_(2) surface-adsorption pathway,which mitigates the overpoten-tials of the oxygen reduction(ORR)and oxygen evolution reaction(OER).As a result,Mn SAs-NC with Mn-N_(4) moiety effectively facilitates the Li_(2)O_(2) nucleation and enables its reversible decomposition.This work establishes a methodology for constructing carbon-based electrocatalysts with high activity and selectivity for Li-O_(2)batteries.

Centrifuge modeling of unreinforced and multi-row stabilizing piles reinforced landslides subjected to reservoir water level fluctuation

With the construction of the Three Gorges Reservoir dam,frequent reservoir landslide events have been recorded.In recent years,multi-row stabilizing piles(MRSPs)have been used to stabilize massive reservoir landslides in China.In this study,two centrifuge model tests were carried out to study the unreinforced and MRSP-reinforced slopes subjected to reservoir water level(RWL)operation,using the Taping landslide as a prototype.The results indicate that the RWL rising can provide lateral support within the submerged zone and then produce the inward seepage force,eventually strengthening the slope stability.However,a rapid RWL drawdown may induce outward seepage forces and a sudden debuttressing effect,consequently reducing the effective soil normal stress and triggering partial pre-failure within the RWL fluctuation zone.Furthermore,partial deformation and subsequent soil structure damage generate excess pore water pressures,ultimately leading to the overall failure of the reservoir landslide.This study also reveals that a rapid increase in the downslope driving force due to RWL drawdown significantly intensifies the lateral earth pressures exerted on the MRSPs.Conversely,the MRSPs possess a considerable reinforcement effect on the reservoir landslide,transforming the overall failure into a partial deformation and failure situated above and in front of the MRSPs.The mechanical transfer behavior observed in the MRSPs demonstrates a progressive alteration in relation to RWL fluctuations.As the RWL rises,the mechanical states among MRSPs exhibit a growing imbalance.The shear force transfer factor(i.e.the ratio of shear forces on pile of the n th row to that of the first row)increases significantly with the RWL drawdown.This indicates that the mechanical states among MRSPs tend toward an enhanced equilibrium.The insights gained from this study contribute to a more comprehensive understanding of the failure mechanisms of reservoir landslides and the mechanical behavior of MRSPs in reservoir banks.

聚四氟乙烯/SiO_(2)复合纤维膜的制备及性能

通过静电纺丝技术制备了具备超疏水性能的PVA/PTFE/SiO_(2)油水分离纤维膜。用SiO_(2)颗粒对聚乙烯醇(PVA)/聚四氟乙烯(PTFE)纤维膜进行二级粗糙结构的构建,得到PVA/PTFE/SiO_(2)复合纤维膜,用X射线衍射、疏水角测试、扫描电子显微镜、能谱、热重-差热分析、红外光谱分析及X射线光电子能谱分析对复合纤维膜进行表征,并对其进行油水分离性及稳定性实验。结果表明,添加SiO_(2)颗粒提高了纤维膜的疏水性能,当SiO_(2)颗粒的质量分数为0.5%时,纤维膜的疏水角平均值达到最大158.9°;该复合膜对不同油水混合物的分离效率均在99.2%以上,循环分离20次后的效率仍保持在98.6%以上。在油水分离方面表现出巨大的应用潜力,同时也表现出优异的稳定性能。

Engineering heterointerfaces coupled with oxygen vacancies in lanthanum–based hollow microspheres for synergistically enhanced oxygen electrocatalysis

The development of high–efficiency and low–cost bifunctional oxygen electrocatalysts is critical to enlarge application of zinc–air batteries(ZABs). However, it still remains challenges due to their uncontrollable factor at atomic level during the catalysts preparation, which requires the precise regulation of active sites and structure engineering to accelerate the reaction kinetics for both oxygen reduction reaction(ORR) and oxygen evolution reaction(OER). Herein, a novel Co–doped mixed lanthanum oxide and hydroxide heterostructure(termed as Co–La MOH|OV@NC) was synthesized by pyrolysis of La–MOF–NH_(2) with spontaneous cobalt doping. Synergistic coupling of its hollow structure, doping effect and abundant oxygen vacancies creates more active sites and leads to higher electroconductivity, which contribute to the better performance. As employed as a bifunctional oxygen electrocatalyst, the resulting 3 Co–La MOH|OV@NC exhibits superior electrocatalytic activity for both ORR and OER. In assembled ZAB, it also demonstrates an excellent power density of 110.5 m W cm^(-2), high specific capacity of 810 m Ah g_(Zn)^(-1), and good stability over 100 h than those of Pt/C + RuO_(2). Density functional theory(DFT) calculation reveals that the heterointerfaces coupled with oxygen vacancies lead to an enhanced charge state and electronic structure, which may optimize the conductivity, charge transfer, and the reaction process of catalysts.This study provides a new strategy for designing highly efficient bifunctional oxygen electrocatalysts based on rare earth oxide and hydroxides heterointerface.

基于皮肤3D快速成像技术对唇部和唇周皮肤衰老分析

采用皮肤3D快速成像系统(简称AEVA-HE)旨在探讨女性唇部及唇周皮肤衰老变化特征。实验选取20名符合条件健康女性志愿者参与测试,并分为青年组和老年组,每组10人,通过采集志愿者面部3D图像,对唇部、唇周皮肤生理参数特征统计分析。结果表明:唇周:青年组和老年组之间皮肤皱纹粗糙度(Ra,Rz)差异性具有统计学意义(P<0.05),青年组唇周皮肤更细腻;下唇纹:对青年组和老年组下唇平滑度(Stm,Sa)比较,未表现统计学意义;唇角:唇部粗糙度和皱纹深度具有统计学意义(P<0.05);唇部:唇部形态参数(Positive volume)结合3D可视化立体形态图,青年组唇部表现更饱满,但未表现统计学意义。结论:通过试验表明AEVA-HE系统可采用客观数据与可视化图像表征唇部和唇周的皮肤纹理结构和形态特征,为化妆品企业与研究机构对唇部和唇周皮肤衰老评价提供技术参考。

Experiments on the characteristics of underwater electrical wire explosions for reservoir stimulation

Underwater shock waves generated by pulsed electrical discharges are an effective,economical,and environmentally friendly means of stimulating reservoirs,and this technology has received much attention and intensive research in the past few years.This paper reviews the main results of recent work on underwater electrical wire explosion(UEWE)for reservoir stimulation.Aplatform is developed for microsecond singlewire explosions in water,and diagnostics based on a voltage probe,current coil,pressure probe,photodiode,and spectrometer are used to characterize the UEWE process and accompanying shock waves.First,the UEWE characteristics under different discharge types are studied and general principles are clarified.Second,the shock-wave generation mechanism is investigated experimentally by interrupting the electrical energy injection into the wire at different stages of the wire-explosion process.It is found that the vaporization process is vital for the formation of shock waves,whereas the energy deposited after voltage collapse has only a limited effect.Furthermore,the relationships between the electrical-circuit and shock-wave parameters are investigated,and an empirical approach is developed for estimating the shock-wave parameters.Third,how the wire material and water state affect the wire-explosion process is studied.To adjust the shock-wave parameters,a promising method concerning energetic material load is proposed and tested.Finally,the fracturing effect of the pulsed-discharge shock waves is discussed,as briefly are some of the difficulties associated with UEWE-based reservoir stimulation.

Rice3K56 is a high-quality SNP array for genome-based genetic studies and breeding in rice(Oryza sativa L.)

Single nucleotide polymorphism(SNP)genotyping arrays provide an optimal high-throughput platform for genetic research and molecular breeding programs in both animals and plants.In this study,a highquality and custom-designed Rice3K56 SNP array was developed with the resequencing data of 3024 rice accessions worldwide,which was then tested extensively in 192 representative rice samples.Printed on the Gene Titan chips of Affymetrix Axiom each containing 56,606 SNP markers,the Rice3K56 array has a high genotyping reliability(99.6%),high and uniform genome coverage(an average of 6.7-kb between adjacent SNPs),abundant polymorphic information and easy automation,compared with previously developed rice SNP arrays.When applied in rice varietal differentiation,population diversity analysis,gene mapping of 13 complex traits by a genome-wide association study analysis(GWAS),and genome selection experiments in a recombinant inbred line and a multi-parent advanced generation inter-cross populations,these properties of the Rice3K56 array were well demonstrated for its power and great potential to be a highly efficient tool for rice genetic research and genomic breeding.

A Review of RGB-D Camera Calibration Methods

RGB-D camera is a new type of sensor,which can obtain the depth and texture information in an unknown 3D scene simultaneously,and they have been applied in various fields widely.In fact,when implementing such kinds of applications using RGB-D camera,it is necessary to calibrate it first.To the best of our knowledge,at present,there is no existing a systemic summary related to RGB-D camera calibration methods.Therefore,a systemic review of RGB-D camera calibration is concluded as follows.Firstly,the mechanism of obtained measurement and the related principle of RGB-D camera calibration methods are presented.Subsequently,as some specific applications need to fuse depth and color information,the calibration methods of relative pose between depth camera and RGB camera are introduced in Section 2.Then the depth correction models within RGB-D cameras are summarized and compared respectively in Section 3.Thirdly,considering that the angle of the view field of RGB-D camera is smaller and limited to some specific applications,we discuss the calibration models of relative pose among multiple RGB-D cameras in Section 4.At last,the direction and trend of RGB-D camera calibration are prospected and concluded.

High-Resolution Mass Spectroscopy for Revealing the Charge Storage Mechanism in Batteries: Oxamide Materials as an Example

The pursuit of high-performance electrode materials is highly desired to meet the demand of batteries with high energy and power density.However,a deep understanding of the charge storage mechanism is always challenging,which limits the development of advanced electrode materials.Herein,high-resolution mass spectroscopy(HR-MS)is employed to detect the evolution of organic electrode materials during the redox process and reveal the charge storage mechanism,by using small molecular oxamides as an example,which have ortho-carbonyls and are therefore potential electrochemical active materials for batteries.The HR-MS results adequately proved that the oxamides could reversibly store lithium ions in the voltage window of 1.5–3.8 V.Upon deeper reduction,the oxamides would decompose due to the cleavage of the C–N bonds in oxamide structures,which could be proved by the fragments detected by HR-MS,^(1)H NMR,and the generation of NH_(3)after the reduction of oxamide by Li.This work provides a strategy to deeply understand the charge storage mechanism of organic electrode materials and will stimulate the further development of characterization techniques to reveal the charge storage mechanism for developing high-performance electrode materials.

Prediction of Coal Bed Methane Recovery Rate and Its Improvement Measures in Dafosi Mine Field

The recovery rate of coalbed methane (CBM) can reflect the mining situation and the residual gas in coal reservoir. It plays an important role in the calculation of the recoverable resources. This paper mainly uses isothermal adsorption curve method and hydraulic model method to predict recovery rate of CBM. The isothermal adsorption curve method considering desorption lag problem in the prediction process, which is more in line with the actual situation. In the hydraulic model method, the recovery rate of “V” type well is the largest in the early stage. But with the time going on, the recovery rate of multilateral horizontal well is greater than vertical well, “U” type well and “V” type well finally. The factors affecting CBM recovery rate include geological characteristics, development conditions and economic factors. The geological characteristics of coal reservoir are the main factors affecting CBM recovery rate, and corresponding measures can be adopted to improve the recovery rate.

Defined organic-octamolybdate crystalline superstructures derived Mo_(2)C@C as efficient hydrogen evolution electrocatalysts

Hydrogen evolution electrocatalysts derived from metal-organic crystalline frameworks can inherit the merits of ordered and adjustable structures with high surface area.In this paper,organic-octamolybdate crystalline superstructures(OOCS)with a fixed stoichiometric ratio of Mo_(8)(L)_(2) and high Mo content(>40 wt%)were synthesized using flexible ligands with controllable lengths(named as OOCS-1-3).Then,molybdenum carbides coated with carbon layers as electrocatalysts(Mo_(2)C@C-1-3)can be obtained directly from a one-step high-temperature carbonization process using OOCS-1-3 as precursors.As a typical example,Mo_(2)C@C-3 exhibits satisfactory hydrogen evolution activity with a low overpotential of 151 m V(1.0 mol/L KOH)at 10 m A/cm^(2) and stability for 24 h.The electrocatalytic activity is mainly from the synergistic interactions between the carbon layers and molybdenum carbide species.Furthermore,compared with the initial content of C,N,Mo in OOCS and Mo_(2)C@C,the catalytic activity increases with the N amount.This work makes organic-octamolybdate crystalline superstructures used as general precursors to product high Mo content electrocatalysts applied in energy storage and conversion fields.

Turbo-shaft engine adaptive neural network control based on nonlinear state space equation

Intelligent Adaptive Control(AC) has remarkable advantages in the control system design of aero-engine which has strong nonlinearity and uncertainty. Inspired by the Nonlinear Autoregressive Moving Average(NARMA)-L2 adaptive control, a novel Nonlinear State Space Equation(NSSE) based Adaptive neural network Control(NSSE-AC) method is proposed for the turbo-shaft engine control system design. The proposed NSSE model is derived from a special neural network with an extra layer, and the rotor speed of the gas turbine is taken as the main state variable which makes the NSSE model be able to capture the system dynamic better than the NARMA-L2 model. A hybrid Recursive Least-Square and Levenberg-Marquardt(RLS-LM) algorithm is advanced to perform the online learning of the neural network, which further enhances both the accuracy of the NSSE model and the performance of the adaptive controller. The feedback correction is also utilized in the NSSE-AC system to eliminate the steady-state tracking error. Simulation results show that, compared with the NARMA-L2 model, the NSSE model of the turboshaft engine is more accurate. The maximum modeling error is decreased from 5.92% to 0.97%when the LM algorithm is introduced to optimize the neural network parameters. The NSSE-AC method can not only achieve a better main control loop performance than the traditional controller but also limit all the constraint parameters efficiently with quick and accurate switching responses even if component degradation exists. Thus, the effectiveness of the NSSE-AC method is validated.

Differentiated self-assembly through orthogonal noncovalent interactions towards the synthesis of two-dimensional woven supramolecular polymers

Molecular weaving is a powerful approach to make molecularly woven materials that have showed unprecedented characteristics and properties intrinsically distinct to those of non-woven materials.We here report a facile and efficient approach for the synthesis of 2D woven supramolecular polymers by differentiated self-assembly through orthogonal noncovalent interactions.Importantly,the difference in binding strength of two orthogonal noncovalent interactions can be used to control the process of molecular weaving.Consequently,single-layered 2D woven supramolecular polymers were synthesized and fully characterized by various techniques.This study demonstrates a controllable method for molecular weaving,and will significantly hasten the development of molecularly woven materials.

Machine learning noise exposure detection of rail transit drivers using heart rate variability

Previous studies have found that drivers’physiological conditions can deteriorate under noise conditions,which poses a potential hazard when driving.As a result,it is crucial to identify the status of drivers when exposed to different noises.However,such explo-rations are rarely discussed with short-term physiological indicators,especially for rail transit drivers.In this study,an experiment involving 42 railway transit drivers was conducted with a driving simulator to assess the impact of noise on drivers’physiological responses.Considering the individuals’heterogeneity,this study introduced drivers’noise annoyance to measure their self-noise-adaption.The variances of drivers’heart rate variability(HRV)along with different noise adaptions are explored when exposed to different noise conditions.Several machine learning approaches(support vector machine,K-nearest neighbour and random forest)were then used to classify their physiological status under different noise conditions according to the HRV and drivers’self-noise adaptions.Results indicate that the volume of traffic noise negatively affects drivers’performance in their routines.Drivers with different noise adaptions but exposed to a fixed noise were found with discrepant HRV,demonstrating that noise adaption is highly associated with drivers’physiological status under noises.It is also found that noise adaption inclusion could raise the accuracy of classifications.Overall,the random forests classifier performed the best in identifying the physiological status when exposed to noise conditions for drivers with different noise adaptions.

Simulation of fire emergency evacuation in a large-passenger-flow subway station based on the on-site measured data of Shenzhen Metro

Because of its large capacity,high efficiency and energy savings,the subway has gradually become the primary mode of transportation for citizens.A high density of passengers exists within a large-passenger-flow subway station,and the number of casualties and injuries during a fire emergency is substantial.In this paper,Pathfinder software and on-site measured data of Pingzhou station in Shenzhen(China)were utilized to simulate a fire emergency evacuation in a large-passenger-flow subway station.The Required Safe Egress Time(RSET),number of passengers and flow rates of stairs and escalators were analysed for three fire evacuation scenarios:train fire,platform fire and hall fire.The evacuation time of the train fire,which was 1173 s,was the longest,and 3621 occupants needed to evacuate when the train was fully loaded.Occupants could not complete the evacuation within 6 mins in all three fire evacuation scenarios,which does not meet the current standard requirements and codes.By changing the number of passengers and the number of stairs for evacuation,the flow rate capacity and evacuation time were explored,which have reference values for safety management and emergency evacuation plan optimization during peak hours of subway operation.

2021年世界鞘翅目现生类群分类年鉴

本文整理并总结了世界鞘翅目2021年发表的新分类阶元、新组合、新异名、分类阶元升级和降级等情况,并单独梳理了中国2021年鞘翅目新增分类群。通过在线数据库检索及相关同行补充,最终共获得了相关文献1,114篇。2021年,世界鞘翅目新分类阶元共计3,375个,包括2个新亚科,1个超族,9个新族,3个新亚族,178个新属,36个新亚属,3,070个新种和76个新亚种,另有1,071个新组合,485个新异名,70个分类阶元升级,26个分类阶元降级。新发表的物种中,隐翅虫科534种,金龟科461种,二者约占总数的31.6%。世界鞘翅目新物种发现数量最多的国家是中国,共发现新属13个,新亚属4个,新种635个,新亚种6个,发表中国新记录亚科2个,新记录属13个,新记录亚属1个,新记录种112个和新记录亚种6个。2021年发表的中国鞘翅目新种有204个隶属于金龟科,新物种发现数量最高的省级行政区是云南省(172个新种及亚种)。

基于上转换荧光纳米材料的智能响应药物系统在肿瘤治疗中的应用

上转换荧光纳米粒子具有优异的理化性质,如稳定的发光性能、可调的发射光谱及相对较低的生物毒性,使其在肿瘤治疗领域展现出较好的应用前景.但是很多上转换纳米粒子介导的肿瘤治疗在可控性及选择性方面仍存在不足,无法有效减小对正常组织的损伤,从而阻碍了其在肿瘤治疗中的进一步发展.合理的结构设计和功能化组装,可以构建上转换纳米粒子智能响应系统.这不仅弥补了传统肿瘤治疗的缺陷,也为开发具备可控性和选择性的肿瘤治疗方案提供了新的思路.本文主要对上转换纳米粒子智能响应药物系统的刺激因素及构建方式进行简要的分析,同时总结了它们在肿瘤治疗中的应用和研究现状,并在此基础上对它们在未来肿瘤治疗中的挑战进行了分析和展望.

工业微生物代谢网络模型的研究进展及应用

基因组规模代谢网络(Genome-scale metabolic network model,GSMM)是工业微生物菌株定向改造过程中一种极为重要的指导性工具,有助于研究者快速获取特定性状的工业微生物,因此越来越受到人们的关注。文中回顾了GSMM的发展历程,总结并评述了GSMM的构建方法,以4种重要工业微生物(枯草芽孢杆菌Bacillus subtilis、大肠杆菌Escherichia coli、谷氨酸棒杆菌Corynebacterium glutamicum和酿酒酵母Saccharomyces cerevisiae)为例,阐述了GSMM在工业微生物中的发展与应用。此外,还对GSMM未来的发展趋势进行了展望。

Early cancer detection by serum biomolecular fingerprinting spectroscopy with machine learning

Label-free surface-enhanced Raman scattering(SERS)technique with ultra-sensitivity becomes more and more desirable in biomedical analysis,which is yet hindered by inefficient follow-up data analysis.Here we report an integrative method based on SERS and Artificial Intelligence for Cancer Screening(SERS-AICS)for liquid biopsy such as serum via silver nanowires,combining molecular vibrational signals processing with large-scale data mining algorithm.According to 382 healthy controls and 1582 patients from two independent cohorts,SERS-AICS not only distinguishes pan-cancer patients from health controls with 95.81% overall accuracy and 95.87% sensitivity at 95.40% specificity,but also screens out those samples at early cancer stage.The supereminent efficiency potentiates SERS-AICS a promising tool for detecting cancer with broader types at earlier stage,accompanying with the establishment of a data platform for further deep analysis.

The bond evolution mechanism of covalent sulfurized carbon during electrochemical sodium storage process

The excellent energy storage performance of covalent sulfur-carbon material has gradually attracted great interest. However, in the electrochemical sodium storage process, the bond evolution mechanism remains an elusive topic. Herein, we develop a one-step annealing strategy to achieve a high covalent sulfur-carbon bridged hybrid(HCSC)utilizing phenylphosphinic acid as the carbon-source/catalyst and sodium sulfate as the sulfur-precursor/salt template, in which the sulfur mainly exists in the forms of C–S–C and C–S–S–C. Notably, most of the bridge bonds are electrochemically cleaved when the cycling voltage is lower than0.6 V versus Na/Na+, leading to the appearance of two visible redox peaks in the following cyclic voltammogram(CV) tests.The in-situ and ex-situ characterizations demonstrate that S^2- is formed in the reduction process and the carbon skeleton is concomitantly and irreversibly isomerized. Thus, the cleaved sulfur and isomerized carbon could jointly contribute to the sodium storage in 0.01–3.0 V. In a Na-S battery system, the activated HCSC in cut off voltage window of 0.6–2.8 V achieves a high reversible capacity(770 mA h g^-1 at 300 mA g^-1). This insight reveals the charge storage mechanism of sulfur-carbon bridged hybrid and provides an improved enlightenment on the interfacial chemistry of electrode materials.