Electronic structures and topological properties of TeSe2 monolayers

The successfully experimental fabrication of two-dimensional Te monolayer films [Phys. Rev. Lett. 119 106101 (2017)] has promoted the researches on the group-VI monolayer materials. In this work, the electronic structures and topological properties of a group-VI binary compound of TeSe₂ monolayers are studied based on the density functional theory and Wannier function method. Three types of structures, namely, α-TeSe₂, β-TeSe₂, and γ-TeSe₂, are proposed for the TeSe₂ monolayer among which the α-TeSe₂ is found being the most stable. All the three structures are semiconductors with indirect band gaps. Very interestingly, the γ-TeSe₂ monolayer becomes a quantum spin Hall (QSH) insulator with a global nontrivial energy gap of 0.14 eV when a 3.5% compressive strain is applied. The opening of the global band gap is understood by the competition between the decrease of the local band dispersion and the weakening of the interactions between the Se p_x, p_y orbitals and Te p_x, p_y orbitals during the process. Our work realizes topological states in the group-VI monolayers and promotes the potential applications of the materials in spintronics and quantum computations.     

面向空地协同应急的地表可通行性分析方法

在野外灾害应急与救援过程中,受灾害或复杂地表环境的影响,快速搜索一条到达目的地的可通行性路径是一项具有挑战性的任务。近些年随着空地协同技术的不断发展,利用无人机为地面车载系统提供其周边环境的数据并搜索可通行路径成为空地协同技术研发的一个热点。本文利用机器学习方法,结合基于无人机获取的野外可见光影像自动生成的数字表面模型(DSM)对该无人机可见光影像进行了详细分类,得到了较传统方法更好的分类结果;然后基于一般性规律,建立了地表可通行性判断条件与通行速度计算公式;再通过引入分类结果以及分类的不确定性因子,对A*算法进行了改进。基于改进的A*算法实现了实验区可通行性路径的快速搜索以及路径的可靠性评价,实验表明本文方法可得到更合理的结果。     

甘肃省和政县野生药用植物移栽试验初探

探索地产野生中药材移栽试种经验,为地产野生药材资源保护开发与鉴识应用提供科学依据,探讨人工种植的可行性。采用野外调查、资料查阅和移栽试验方法,了解药用植物生境、采挖野生中草药活株异地集中移栽试种。百草园成功移栽野生药用植物182种,建成和政县当地野生药材活体标本园,已用于科普宣传、参观赏识及示教鉴识。野生药用植物移栽试种是可行的,且本地移栽成活率较高,移栽成功的关键在于野生株适宜的模拟生境与合理的养护管理;百草园可作为临夏地区中草药科普园、鉴赏园及和政当地中草药科研基地,供鉴识应用与开发保护系统研究,为将来引种驯化、迁地保护及人工种植提供了科学依据。     

气体容量法测定单质硅的改进

对测定单质硅的气体容量法进行了改进,在测量装置中增加了恒温系统、柱形称样器,并扩大了量气管的量程。最佳反应碱度为200g·L-1氢氧化钠溶液65mL,反应时间为1h。对不同含量单质硅样品进行测定,测定值的相对标准偏差(n=6)在0.32%~0.47%之间,偏差在-0.45%~0.40%之间。     

胡椒基咪唑盐类化合物的合成及生物活性研究

从胡椒酸出发,通过还原、甲磺酸酯化、偶联和成盐四步反应合成了-系列新型的胡椒基咪唑盐类化合物,其结构经1H NMR,13C NMR,HRMS以及X射线单晶衍射确定.对合成的新化合物进行了体外抗肿瘤细胞毒活性筛选,结果表明,1-((苯并[d][1,3]二氧杂环戊烯-5-基甲基)-3-(2-萘甲基))-5,6-二甲基-1H-苯并[d]咪唑-3-溴盐(30)具有显著的细胞毒活性,对HL-60、SMMC-7721、A-549、MCF-7和SW-480肿瘤细胞株的活性均优于顺铂(DDP),尤其对HL-60肿瘤细胞株表现出较好的选择性细胞毒活性,其IC50值约为顺铂的7.2倍.进一步研究表明,化合物30具有诱导SMMC-7721细胞株在细胞周期G0/G1期阻滞和细胞凋亡的作用.     

云南蕊木茎中的抗炎吲哚生物碱

应用多种色谱和波谱学方法,从云南蕊木(Kopsia officinalis)茎中分离鉴定了27个单萜吲哚生物碱,包括7个新化合物kopsiofficines A^G和20个已知化合物.此外,建立脂多糖(LPS)诱导的小鼠巨噬细胞RAW 264.7炎症模型,通过测定IL-1β,PGE2和TNF-α炎症因子释放评价生物碱的抗炎活性.结果表明,kopsiofficines A(1),kopsiofficines B(2),kopsiofficines D(4),kopsiofficines F(6),kopsiofficines G(7),12-methoxykopsine(11),kopsinoline(15),(-)-N-methoxycarbonyl-11,12-methylenedioxykopsinaline(16),kopsinine(18)和kopsinic acid(20)表现出显著的抗炎活性,与阳性对照(地塞米松)基本相当.研究发现C-5位丙酮基取代的单萜吲哚生物碱的抗炎活性明显强于原型生物碱,推测丙酮基可能是抗炎活性的药效促进基团,研究结果为进一步的结构修饰和药理学研究提供了线索.     

淮河蚌埠段浮游生物群落RAPD指纹与水体重金属含量的相关性研究

在测定淮河蚌埠段河水重金属含量的基础上,对淮河蚌埠段浮游生物群落DNA多态性进行RAPD指纹技术分析,探讨了重金属含量与浮游生物群落RAPD指纹的相关性.结果表明,所筛选的11条随机引物共获得97条谱带,多态率为85.1%,所有引物在各位点可获得7~11条扩增谱带,平均8.9条.淮河蚌埠段河水中Mn、Fe和Pb的含量高于《中华人民共和国生活饮用水卫生标准》,Fe和Pb的含量高于世界卫生组织《饮用水标准》.Hierarchical cluster聚类分析表明,淮河蚌埠段浮游生物群落RAPD指纹与淮河蚌埠段水体重金属含量的聚类结果基本一致,浮游生物群落RAPD指纹与水体重金属浓度呈现较好相关性,为建立新的淮河水质监测与评价技术提供科学参考.     

Way of designing a periodic etched grating coupler with fully slots

In order to couple into or out of a silicon photonic waveguide on silicon on insulator （SOI） substrate from optical fibers, we present a simple but practical method to design a grating coupler. The grating is periodic with fully etched slots; strong reflection between the fully etched grating and the waveguide is avoided by adding an antireflection interface. Theoretical coupling efficiency up to 43% is demonstrated. A taper waveguide used to link the grating and waveguide is also designed.     

Dispersion imaging spectrometer for detecting and locating energetic targets in real time

A conceptual dispersion imaging spectrometer(DIS) is proposed.It consists of a telescope,four prisms,an imaging lens,and a detector.The first prism allows only the first set of wavelengths along the first direction to pass and disperse.The second prism allows only the second set of wavelengths along the second direction,which is perpendicular to the first.The third and fourth prisms are used to compensate for the angular deviations from the optical axes of the first and second prisms,respectively.The proposed DIS disperses the spectra of a target to form an L-shaped dispersion pattern(LDP).The theoretical calculation and numerical simulation of the LDP are presented.The DIS can locate multiple targets based only on data obtained from a single frame.It is suitable for detecting and locating energetic targets in real time.     

鹤煤年产10万吨1,4—丁二醇(一期)项目乙炔站工程不发火花地面施工技术

乙炔站工程共有两项单体建筑工程施工内容,一项是电石破碎厂房及输送,另一项是电石发生(乙炔发生)。1.电石破碎厂房及输送:本工程为单层钢筋混凝土排架结构,排架横向1跨,纵向10跨,平面尺寸为60m×36m,高7.5m。屋架采用轻型屋面梯形钢屋架,屋面和部分墙面的维护采用轻钢结构。排架厂房大部分采用柱下钢筋混凝土独立基础,部分排架柱采用筏板基础。地面面积2136.96m2。2.电石发生(乙炔发生):本工程为5层钢筋混凝土框架结构,框架横向5跨,纵向6跨,平面尺寸33.18m×34.00m,高23.5m。部分屋面采用轻钢维护。厂房柱采用柱下钢筋混凝土独立基础。地面、楼面面积2366m2。据统计,乙炔站工程共需要施工不发火花地面、楼面面积,合计:4502.96m2。不发火花地面特性