Mechanical properties of L929 cells measured by atomic force microscopy: Effects of anticytoskeletal drugs and membrane crosslinking

To shed light on the architecture of the cytoskeleton, we used the atomic force microscope (AFM) to measure the elasticity, viscoelasticity, and plasticity of L929 cells. The initial elastic response (Young's modulus ～ 4,000 Pa) of the cells to an applied force was followed by a slow compression of the cytoskeleton (τ_1/2 ≈ 10 s). When force application was terminated, the cytoskeleton underwent a sudden partial decompression and a subsequent slow, incomplete recovery. The role of the cytoskeletal elements in cell mechanics was accessed in AFM measurements carried out on cells treated with cytochalasin D, nocodazole, or col-cemid. Cytochalasin D treatment reduced both elasticity (～45%) and cytoplasmic viscosity (～65%), whereas cells treated with nocodazole or colcemid exhibited a marked increase in elasticity (～100%) and a slight increase in viscosity (～15%). The AFM force measurements also provided evidence that the cell membrane and the cytoskeleton are mechanically coupled. Tightly adherent cells were stiffer than cells that were loosely attached. Moreover, cells crosslinked with either glutaraldehyde, 3,3 ‘-dithiobis’sul-fosuccinimidylpropionate] (DTSSP), or Concanavalin A were more rigid than untreated cells. It is of interest that cells crosslinked with Concanavalin A, but not DTSSP, displayed plastic behaviors that may reflect the induction of cytoskeletal reorganization by Concanavalin A.     

亚精胺诱导DNA凝聚的有序性的AFM研究

观察生物体内ＤＮＡ凝聚参与物—亚精胺对ＤＮＡ的凝缩作用将有利于深入理解ＤＮＡ在体内的紧密存储机制。本文采用原子力显微镜（ＡＦＭ）研究了在不同的ＤＮＡ浓度下亚精胺—ＤＮＡ凝聚体的形态变化。研究表明：随着体系中ＤＮＡ浓度的变化,亚精胺将诱导ＤＮＡ形成两种类型的凝聚物（类型Ⅰ和类型Ⅱ）。当λ－ＤＮＡ浓度低于１ｎｇ／μｌ,亚精胺可诱导λ－ＤＮＡ形成一种特殊的结构—环形凝聚体,其体积与单个λ－ＤＮＡ的体积近似（类型Ⅰ）;当λ－ＤＮＡ浓度介于１ｎｇ／μｌ和１０ｎｇ／μｌ之间,可观察到由许多小颗粒堆积而成的多分子凝聚的环状体（类型Ⅱ）。对类型Ⅱ的高度分析表明它可能具有分层结构,统计表明其组成颗粒在粒径上和单个类型Ⅰ凝聚体相近。这些观察暗示了亚精胺诱导ＤＮＡ凝聚可能是一个分级自组装过程。     

海藻酸薄膜表面超微结构的原子力显微镜研究

本文采用原子力显微镜（ＡＦＭ）对海藻酸生物薄膜表面的超微结构进行了实验研究,选择出最佳观察方法。结果发现薄膜上分布不规则的微孔,其长短孔径之比大约为３：２,微孔的中心距为孔径的２倍。     

温度及氩缓冲气体对锶原子共振滤波器响应时间的影响

响应时间是原子共振滤波器的性能的重要参数。本文说细研究了不同温度及不同氩缓冲气压对锶原子共振滤波器响应时间的影响,为锶原子共振滤波器作成器件和其它滤波器的研究提供了有价值的实验结果。     

乙酰胆碱酯酶分子的原子力显微成像

本文研究了用原子力显微技术对乙酰胆碱酯酶进行成像的方法。在新鲜裂解的云一表面镀一层金膜,金膜与疏基丙酸（ＭＰＡ）的疏基形成Ｓ－Ａｕ键。使ＭＰＡ的游离羧基再通过碳二亚胺反应与ＡＣｈＥ的碱性氨基酸的氨基形成肽键连接,ＡＣｈＥ因而被固定于支持物表面,这样固定的ＡＣｈＥ可获得清晰成像而不脱落。     

原子吸收光度法测定渣样中的低含量金属元素

利用原子吸收光度法连续测定渣样中的Ｍｇ、Ｍｎ、Ｐｂ、Ｚｎ、Ｃｕ、Ｋ、Ｎａ、Ｌｉ含量,称样、溶样只需一次,就可完成８种元素的连续测定。该方法操作简便、快速,而且测定结果准确可靠,测定各元素的相对标准偏差为０．３％～２５％,回收率达９７％～１０２％。     

Nanoscale Indentation and Scratch of Short Carbon Fiber Reinforced PEEK/PTFE Composite Blend by Atomic Force Microscope Lithography

The atomic force microscope (AFM) has become a popular tool for characterizing surfaces of different types of materials. In this paper a new technology of AFM–SPM lithography was used to conduct nanoscale scratch and indentation tests on a short carbon fiber reinforced PEEK/PTFE composite blend. In the scratch test, by moving the tip across the surface at constant velocity and fixed applied force, grooves with nanometer scale dimensions were fabricated on the PEEK matrix surfaces. The grooves consisted of a central trough with pile-ups on each side. These grooves provided information about deformation mechanisms and scratch resistance of the individual phases. In the nanoscale indentation and scratch of the polymeric phases, microploughing and microcutting are the dominant wear mechanisms. The harder phases, i.e., graphite and carbon fibers, get worn by microcracking events.     

金刚石热化学抛光的机理研究

在完成了金刚石表面的热化学抛光后,应用原子力显微镜(AFM)观测加工后表面形成的微观结构,并用扫描电子显微镜(SEM)加以校验.借助X射线光电子能谱(XPS)技术对采样所得铁盘的两个不同区域进行多方面的对比分析,初步确定了抛光过程中发生的理化反应和结果生成物.并在此基础上对热化学抛光各阶段的工作机理作了深入探讨,明确了研磨表面平整、出现凹槽等现象的原因.结论与实验分析结果能够较好地吻合.     

从原子结构探讨贵金属在提取冶金过程中的行为

从原子结构特征分析了第Ⅷ族和IB族中Fe、Co、Ni、Cu 3d贱金属元素与其余8个贵金属元素化学性质的差异,以及Ru、Rh、Pd、Ag 4d贵金属与Os、Ir、Pt、Au 5d贵金属化学性质的差异。指出横向比较时,它们的化学稳定性都是从左到右增大;纵向比较时,化学稳定性是3d<4d<5d。以从硫化铜镍矿中提取富集贵金属为例,讨论了焙烧-还原熔炼-氧化吹炼等火法过程及电解富集、阳极泥硫酸化处理、湿法氯化、加压氧化、选择性还原等湿法过程中贵金属的行为。     

基于AFM的Si纳米结构的加工

介绍了通过使用原子力显微镜,在H钝化Si(100)的表面局部阳极氧化反应的表面氧化图案上刻写的纳米级Si结构加工。这种氧化图形可被用作Si的可选择性蚀刻工艺的掩膜。带有临界特性的小到30nm的边门Si场效应晶体管也通过这种方法加工。