Structure of carbon nanotubes probed by local and global probes

A review is proposed of different techniques available today for the characterization of the atomic structure of carbon nanotubes. This review covers the electron microscopies, various diffraction techniques, scanning probe microscopies, and optical spectroscopies, including Raman scattering. The advantages and limitations of the characterization techniques are discussed.     

Electron transport in direct methanol fuel cells

A three-dimensional (3D), two-phase, isothermal model of direct methanol fuel cells (DMFCs) was employed to investigate effects of electron transport through the backing layer and the land in bipolar plates. It was found that the electronic resistance of the backing layer, affected by backing layer electronic conductivity, backing layer thickness and flow channel width, played a relatively important role in determining the current density distribution and cell performance. In order to ignore the electron transport effect on the average current density, the minimum electronic conductivity of the backing layer has to be 1000 S m⁻¹, with the relative error in the average current density less than 5%, under the given conditions.     

In0.53Ga0.47As／InP异质结光电二极管的深能级

采用深能级瞬态谱仪（ＤＬＴＳ）测定了Ｉｎ０．５３Ｇａ０．４７Ａｓ／ＩｎＰ异质结光电二极管的ＤＬＴＳ谱。发现存在一电子陷阱，该陷阱能级位于导带底以下０．４４ｅＶ处，能级密度为３．１０×１０１３ｃｍ－３，电子俘获截面为１．７２×１０－１２ｃｍ－２。由于深能级的存在，导致了该器件存在一种新的“暗电流”──“深能级协助隧穿电流”。     

浓缩~(235)U诱发免疫细胞凋亡的电镜和琼脂糖凝胶电泳研究

研究了浓缩235U内照射诱发人淋巴细胞白血病细胞株Molt－4细胞和巨噬细胞株Ana－1细胞的细胞调亡。估算了浓缩235U在不同阶段培养细胞中的辐射累积吸收剂量。通过电镜对免疫细胞的形态观察，发现Molt－4和Ana－1细胞在受235U内照射作用下可呈现核染质边聚，DNA链断裂和膜包裹的凋亡小体形成。对Molt－4和Ana－1细胞的DNA抽提，进行DNA琼脂糖凝胶电泳也显示出阶梯状条带形成的细胞调亡特征。从而证实了浓缩235U内照射可导致免疫细胞Molt－4和Ana－1细胞的凋亡发生。     

砷化镓材料中EPR“As_(Ga)”的退火行为

本文比较了中子辐照。压缩变形和原生LEC砷化镓等三种不同来源样品的EPR“As_(Ga)”的Hamiltonian参数。并系统地研究了EPR“As_(Ga)”的浓度和低温光猝灭行为随退火温度的变化,从而进一步验证了EPR“As_(Ga)”的本性,即除孤立As_(Ga)反位原子外,还可能包括As_(Ga)的一些空位络合物。这些不同本性的EPR“As_(Ga)”缺陷及其它有关的缺陷在样品热处理过程中可能相互转化。按照物理化学中Le Chatlier原理,缺陷的原始浓度和晶体内部应变能似应是引起这些转化反应的重要因素。     

电子和β射线两用外推电离室的研制

本文研制了一台测量电子束和β射线吸收剂量的外推电离室,其空腔室壁材料可拆换并分别与空气、组织和硅等效,收集电极名义直径为1.5、3、10和30mm,空气空腔可变范围为0.2～15mm。该外推电离室具有在空腔内部测温,自动改变窗口上方材料厚度及采用微型计算机控制等特点。适用于测10 MeV能量以下,剂量率为10~5～10~(-3)Gy/h的电子或β射线吸收剂量。整个外推电离室自动测剂量系统在测~(204)TLβ放射源表面剂量率的不确定度为2.3％。测1.5 MeV电子束在硅和哈密瓜深部剂量率时,不确定度分别为4.0％和2.8％。     

Electron Microscopy Imaging Applications of Room Temperature Ionic Liquids in the Biological Field: A Review

For biological imaging using electron microscopy (EM), the use of room-temperature ionic liquids (RTILs) has been proposed as an alternative to traditional lengthy preparation methods. With their low vapor pressures and conductivity, RTILs can be applied onto hard-to-image soft and/or wet samples without dehydration – allowing for a more representative, hydrated state of material and opening the possibility for visualization of in situ physiological processes using conventional EM systems. However, RTILs have yet to be utilized to their full potential by microscopists and microbiologists alike. To this end, this review aims to provide a comprehensive summary of biological applications of RTILs for EM to bridge the RTIL, in situ microscopy, and biological communities. We outline future research avenues for the use of RTILs for the EM observation of biological samples, notably i) RTIL selection and optimization, ii) applications for live cell processes and iii) electron beam and ionic liquid interaction studies.