Microscopy structural aspects

Electron microscopy (EM) has played a central role in many aspects of research on microtubules and their main protein component, tubulin. MTs were first identified in electron micrographs of plant material [1], Characteristics of the basic structural aspects of MTs were also determined by EM, revealing that MTs are hollow tubes composed of protofilaments (pf). There are most often 13 pfs, but this number can vary at least from 9 to 16. Subsequent work showed that the pfs are composed of aP-tubulin dimers arranged head-to-tail. 

In the first part of this contribution we will focus on the well known YBa2Cu307 superconductor this material allows a large number of substitutions without drastically altering its structural aspects, but with sometimes completely different physical properties. In the second part, we will concentrate on the more recent Hg-based superconductors and illustrate the extreme importance of the different electron microscopy techniques in the development of new superconducting compounds. 

Electron microscopy techniques are essential tools needed for the investigation of the local structure and composition of grain boundaries in high-temperature superconductors. While we have emphasized structural aspects here, analytical characterizations (see Chapters 8 and 11) are extremely important and must be part of establishing direct connections to transport properties. 

Oxide passive film formation on metals and their crystaUine structure have been reviewed recentiy [73,87]. The nanometer-scale chemical and structural aspects have been reviewed by Maurice and Marcus [88]. The growth of 2-D anodic oxide films and the nanostructure of 3-D films are considered in this review. The structures of stainless steels [27,89], Co- [90], Ni- [91], and Cu-based alloys [92,93] have been studied with atomic force microscopy (AFM) and scanning tunneling microscopy (STM). 

With respect to the clay particles, dispersion, polymer nanocomposites show extremely complex morphologies. As a consequence, detailed morphological studies results are difficult to obtain by means of electron microscopy and X-ray diffraction alone. The transport properties characterization can be quite successful in elucidating structural aspects at a level which may be insensitive to the other techniques. 

The development of high-magnification microscopy made it possible to create images of biological materials at the molecular level. Many of these images show structures that have liquid crystalline aspects. Shown here are aligned mosaic virus molecules and protein molecules in voluntary muscles. In addition, all cell walls are picket fences of rod-shaped molecules in regular yet fluid arra. ... 

The present volume contains the lectures given during this ASI and covers almost all theoretical and practical aspects of advanced transmission electron microscopy techniques and crystallographic methods that are relevant for determining structures of organic and inorganic materials. Moreover a number of extended abstracts on the presented posters during this ASI have been added to this volume. 

The most important aspect of electron microscopy in solid state chemistry lies in its ability to elucidate problems that are beyond the capability of X-ray or neutron crystallography. High-resolution electron microscopic (HREM) images show local structures of crystals in remarkable detail in Fig. 2.10 we show the HREM image of Big, W03 obtained with the Cambridge University 500 kV microscope to show the improved resolution compared with the image obtained with a 200 kV microscope... 

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