SEM在宝石学中的应用

本文简要介绍了扫描电子显微镜的工作原理，并结合能谱仪，探讨了扫描电子显微镜在宝石学中鉴定天然宝石与合成宝石及优化宝石等方面的应用．     

聚苯胺修饰电极的制备与形貌、阻抗表征

运用循环伏安(CV)法制取聚苯胺,结合扫描电子显微镜(SEM)、阻抗谱(EIS)等手段,对聚苯胺的表面形貌及其特征进行研究,并建立了聚苯胺覆盖Pt电极的阻抗模型.实验表明,随着循环次数的增加,聚苯胺膜厚增加,而且所制得的聚苯胺膜呈现多孔、疏松的特征,符合其作为基体材料的特点.     

SEM analysis of the changes of carbon layer structure of mesocarbon microbeads heat-treated at different temperatures

Mesocarbon microbeads (MCMB) with narrow size distribution, excellent sphericity and no obvious conglutination have been prepared with a coal tar pitch containing quinoline insolubles (QI) as the raw material. Optical microscopy and scanning electron microscopy (SEM) are used to examine the structure of the MCMB. It has been found that SEM technique shows the structural information of MCMB clearly in the form of micrographs even when the structure of MCMB is complex, while the optical technique is useful for analysis of the regular structure of the mesophase spheres but cannot be effectively used to analyze either the complex structure of the green MCMB or the structures of the further heat-treated ones at different temperatures. According to the characteristics of the carbon layers, the structures of the as-prepared MCMB in the present experiment could be classified as (I) Parallel Layer type structure and (2) Bent Layer type structure with the carbon layers gathering at one or two points in the MCMB. In the experiments, SEM is also utilized to investigate the structures of MCMB that are heat-treated at different temperatures. It has been found that the MCMB without any further heat-treatment show no layered-carbons, while the ones heat-treated at temperaturehigher than 1000℃ exhibit obvious layered carbons across their sections. When increasing the heat-treatment temperature, the carbon layers become thinner and flatter.     

TRPC通道的结构机制研究进展

经典型瞬时受体电势通道(transient receptor potential canonical channel, TRPC)是一类重要的非选择性阳离子通道.该通道家族包含多个成员,在体内广泛分布,参与多种生理病理过程,是治疗如局灶节段性肾小球硬化症(focal segmental glomerular sclerosis, FSGS)等疾病的药物靶点.得益于单颗粒冷冻电子显微镜技术的快速发展,目前已解析的TRPC通道家族多个成员的结构展示了TRPC通道四聚体的组装模式、各结构域的空间排布、具有调节功能的钙离子结合位点和多种小分子化合物的作用位点.这些结构信息与功能实验相辅相成,共同揭示了TRPC通道被钙离子双向调节的机制、小分子化合物的作用机制,以及在人类遗传疾病中发现的致病突变体的激活机制.这些研究进展为进一步探索TRPC通道的工作原理和靶向TRPC通道的药物开发提供了坚实的基础.     

An effective amperometric biosensor based on graphene modified gold nanowire arrays for glucose detection

A novel glucose biosensor based on graphene nanosheets （GNs） modified gold nanowire arrays （AuN- WAs） electrode was constructed. Highly ordered gold nanowire arrays were prepared by direct electrodeposition in anodic aluminum oxide templates. GNs were synthe- sized through a public route involving graphite oxidation, exfoliation, and chemical reduction. Field emission scan- ning electron microscope and high-resolution transmission electron microscope were employed to characterize the as- prepared AuNWAs and GNs. Glucose oxidase was immobilized on the surface of GNs-AuNWAs modified electrode via a cross-linking method. The cyclic voltam- metry results showed that the GNs-AuNWAs-based glu- cose biosensors have high catalysis activity to hydrogen peroxide （H2O2） than those modified with GNs or AuN- WAs only. Furthermore, amperometric response was employed to detect glucose concentration owing to its simplicity, high selectivity, and relative low cost. Glucose biosensors based on GNs-AuNWAs showed excellent performance with high sen- sitivity of 40.25 μA cm^-2 （mmol/L）^-1, low detection limit of 0.02 mmol/L, and a linear range from 0.02 to 3 mmol/L.     

Atmospheric-pressure Air Plasma Treatment of Polyester Fabrics for Inkjet Printing with Pigment Inks

Without any preprocessing,polyester fabric has lower ability to hold on water and inks due to the smooth morphology of polyester fibers. Therefore, patterns directly printed with pigment inks have poor color yields and bleed easily. Pretreatments of polyester fabric were carried out with atmospheric air plasma under different experimental conditions. After plasma treatment the samples were printed with magenta pigment ink. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyse...     

制备特定尺寸的纳米金颗粒方法及性能表征

通过化学还原法制备出不同粒径的纳米金颗粒。利用紫外可见分光光度计和透射电子显微镜对纳米金颗粒的形貌及尺寸进行表征。讨论了还原剂种类、还原剂用量、试剂加入顺序、反应温度等因素对纳米金颗粒稳定性、粒径、形貌和分散性的影响。结果表明：Na3C6H5O7为还原剂制得纳米金颗粒粒径在15-20 nm之间,NaBH4为还原剂制得的...     

基于扫描电子显微镜的单根一维纳米材料原位场发射性能研究

基于扫描电子显微镜和纳米探针技术,展示了一维纳米材料原位场发射的测量方法和实例。实验以钨针尖为接收极,纳米材料为发射极,通过结合扫描电子显微镜的实时成像功能,纳米探针的精确操纵及电学测量技术以及激光辐照功能,系统研究了极间距离D、形貌变化、吸附气体和激光注入对单根多壁碳纳米管和氧化锌纳米线场发射性能的影响。结果表明,当D远小于纳米材料长度L的3倍时,D越小,开启场强和阈值场强越大,场发射性能越弱。此外,纳米线尖端曲率半径越大,场增强因子越小,场发射性能越弱。研究还发现O2的脱附和激光辐照有助于纳米材料场发射性能的提高。     

低温热解二茂铁制备碳包裹纳米铁及其结构

以二茂铁为碳源和铁源在100 mL不锈钢高压釜中经520℃直接热解制备碳包裹纳米铁.研究不同反应物量对热解产物的影响,并采用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对热解产物的物相、形貌和结构进行分析.结果表明:二茂铁520℃热解碳产物以无定形炭和Fe3C相为主.当二茂铁的量为1 g时,热解产物是蜂窝状的多孔炭...     

东太平洋沉积物中自然GaN晶体的首次报道

本文报道了在东太平洋表层沉积物中发现的天然GaN晶体, 这是天然GaN晶体在自然界中首次被发现. 天然GaN晶体的确定是通过透射电子显微镜(TEM), 能量损失谱(EELS)和X射线能谱(EDS)等综合微束分析技术完成的. 该天然GaN晶体属于六方晶系, 晶胞参数为: a=b=0.3186 nm; c=0.5178 nm, P6₃mc, 其结构与高温高压实验合成的人造GaN晶体结构完全吻合. 在TEM下, 该GaN晶体呈现完好的晶体形态, 可以排除它们是异地搬运的人工合成的产物. 由于发现GaN的站位位于东太平洋CC区(克拉里昂断裂带—克利帕顿断裂带之间), 区内发育有断裂构造,受到火山作用和热液活动影响,推测其成因可能与热液活动或深部的高温、高压作用有关, 但其形成的确切温压条件和地质环境尚需进一步深入研究.