气候对不同地区川金丝猴出生模式的影响

多数非人灵长类动物的交配与出生有着严格的季节变化,这种季节性除受自身生理机制影响外,还受栖息环境的气候、海拔和食物供应的影响。了解栖息于不同地区的同种非人灵长类动物出生季节性差异有助于了解环境变量对动物繁殖的影响。本研究于2023年1—8月,采用焦点动物取样法,探索了四川白河国家级自然保护区王家山区域和湖北神农架国家公园大龙潭区域川金丝猴(Rhinopithecus roxellana)群体中婴猴出生模式与季节性气候变化之间的关系。结果发现,两个地区川金丝猴种群中的婴猴集中在3—5月出生,但白河种群的出生季节时间跨度较长,1—2月、7—8月都有婴猴出生;尽管两组猴群出生模式不同,但均发生于气温回暖,降水上升的时期;白河种群周婴猴/成雌值(I/F)变化与周平均气温、周降水量呈正相关;神农架种群周I/F变化与周平均气温呈正相关,但是与周降水量相关性不明显。气温上升可能是促进怀孕雌猴进行分娩环境响应因素,降水量则通过影响食物供应的方式来引发繁殖事件。

深厚软土地层超长超大直径扩底桩承载力性状及机理研究

深厚软土地区超长超大直径扩底桩荷载传递机理复杂,且国内相关工程数量少,可供施工人员参考资料有限,传统桩基理论已无法合理的分析其工作机理和受力特性。文章依托深圳大运枢纽超长超大直径扩底桩工程,通过现场静载试验与数值仿真分析,研究了在深厚软土地层中超长超大直径扩底桩在静载作用下的荷载传递机理及沉降规律。基于荷载传递法,针对深厚软土地基的特殊性质,考虑了桩侧土初始剪应力、软化特性以及桩端土加工硬化特性,进行了沉降公式的推导。并基于MATLAB,开发了高性能的迭代算法以研究单桩的承载力性状。结果表明:现场试验、数值模拟与理论算法得到的荷载-沉降曲线线型吻合较好。当传递深度达到约0.4倍桩长时,下部桩身基本不产生压缩变形;桩基极限承载力大于设计值,存在较大的承载潜力,桩基设计较合理,满足承载力要求,可以为同类地区桩基工程设计与施工提供参考。

基于弱光栅技术的基坑围护结构变形自动化监测研究

地连墙的失稳和破坏会造成重大的经济损失和人员伤亡,因此对地连墙的变形监测尤为重要。然而,传统监测技术难以高效准确地获取地连墙分布式位移数据。针对目前地连墙深部位移监测技术的不足,本文提出了一种基于弱光栅技术的基坑围护结构变形监测方法,并将其应用到深圳某基坑工程中,对开挖过程中地连墙的变形情况实时监测,结果表明:本文提出的监测技术可实时获取地连墙的应变、弯矩、位移等变形信息,精准地确定地连墙的状态,为保障基坑工程安全顺利的施工提供一种可靠的技术手段。

Improving the device performances of two-dimensional semiconducting transition metal dichalcogenides: Three strategies

Two-dimensional(2D)semiconductors are emerging as promising candidates for the next-generation nanoelectronics.As a type of unique channel materials,2D semiconducting transition metal dichalcogenides(TMDCs),such as MoS2 and WS2,exhibit great potential for the state-of-the-art fieldeffect transistors owing to their atomically thin thicknesses,dangling-band free surfaces,and abundant band structures.Even so,the device performances of 2D semiconducting TMDCs are still failing to reach the theoretical values so far,which is attributed to the intrinsic defects,excessive doping,and daunting contacts between electrodes and channels.In this article,we review the up-to-date three strategies for improving the device performances of 2D semiconducting TMDCs:(i)the controllable synthesis of wafer-scale 2D semiconducting TMDCs single crystals to reduce the evolution of grain boundaries,(ii)the ingenious doping of 2D semiconducting TMDCs to modulate the band structures and suppress the impurity scatterings,and(iii)the optimization design of interfacial contacts between electrodes and channels to reduce the Schottky barrier heights and contact resistances.In the end,the challenges regarding the improvement of device performances of 2D semiconducting TMDCs are highlighted,and the further research directions are also proposed.We believe that this review is comprehensive and insightful for downscaling the electronic devices and extending the Moore’s law.

Controlled Syntheses and Multifunctional Applications of Two-Dimensional Metallic Transition Metal Dichalcogenides

CONSPECTUS:Among two-dimensional(2D)layered materials,metallic transition metal dichalcogenides(MTMDCs)are emerging as promising candidates in many application aspects(e.g.,electronics,spintronics,and energy related fields,etc.)in view of their ultrahigh electronic conductivities,newfangled room-temperature ferromagnetism(e.g.,VSe_(2),VTe_(2)),and excellent catalytic activities.Specially,2D TaX_(2) and VX_(2)(X=S,Se,Te)materials stand in a vital place on account of their exotic physical and chemical properties.Notably,the controlled synthesis of such materials is the premise for exploring the aforementioned properties and applications.Among the reported preparation methods,chemical vapor deposition(CVD)is proven to be a promising approach in view of its scalability,simple operation,low cost,etc.This method has been employed to synthesize various 2D layered materials and heterostructures in a well-controlled fashion.Nevertheless,in view of the complicated growth mechanism and process,the CVD growth of ultrathin TaX_(2) and VX_(2) nanosheets/films remains extremely challenging.In addition,the application explorations of 2D TaX_(2) and VX_(2) in the energy related fields and electronic devices are still in the primary stage.In this Account,we review the up-to-date advances regarding the CVD syntheses of 2D TaX_(2) and VX_(2)(e.g.,TaS_(2),TaSe_(2),VS_(2),VSe_(2),and VTe_(2),etc.)and air-stable MTMDCs(e.g.,PtSe2,NiTe2),as well as their multifunctional applications in the energy related fields and electronic devices.First,the CVD growth of TaX_(2) and VX_(2) nanosheets/films with tunable thicknesses/domain sizes and the MTMDCs/semiconducting TMDCs vertical heterostructures are systematically summarized.Second,the application explorations of CVD-synthesized 2D TaX_(2) and VX_(2) as high-performance electrode materials in electrocatalytic hydrogen evolution reaction(HER)and electronic devices are introduced,respectively.Third,the CVD syntheses of 2D MTMDCs with robust environmental stability and novel physical properties(e.g.,semimetal−semiconductor transition,magnetism)are discussed.In the end,the challenges regarding the preparations and multifunctional applications of 2D MTMDCs are highlighted,and the future research directions are also proposed.We believe that this Account is comprehensive and insightful for the CVD syntheses of high-quality 2D MTMDCs materials toward versatile applications.