Microscopic investigations limitations

The various techniques which may be used to provide optimum conditions for the examination of specimens have been described [202—205]. If the sample is opaque, then microscopic investigation is limited to the surface. The depths of penetration for the study of transparent crystals are controlled by the limited depth of field of the optical microscope at high magnifications. This limitation can sometimes be overcome by cleavage of the crystal at an appropriate value of a and examination of the surfaces exposed [120],... 

Electron microscopic techniques, on the other hand, make direct observation possible hence provide information on the shape of the vesicles as well as presence/absence of any aggregation and/ or fusion. The drawback of the microscopic investigations is that the number of particles that can be studied at any certain time is limited. Therefore, the general approach for the determination of size distribution of nanoliposomal formulations should be to use as many different techniques as possible. 

Even if one solves the indexing problem and then proceeds with the analysis by an evaluation of measured reflection intensities, one cannot expect to achieve an accuracy in the crystal structure data which would be comparable to those of low molar mass compounds. This is not only a result of the lack of single crystals, but represents also a principal property In small crystallites, as they are found in partially crystalline polymers, lattice constants can be affected by their size. In many cases crystallites are not only limited in chain direction by the finite thickness of the crystalline lamellae but also laterally since polymer crystallites are often composed of mosaic blocks. Existence of these blocks is indicated in electron microscopic investigations on... 

This study Illustrates the use of situ MBS as applied to the Investigation of species Involved In redox processes In porous electrodes. It Is expected that a systematic utilization of this technique may enable the acquisition of microscopic level Information of difficult accessibility with other spectroscopic methods, although limited to only Mossbauer active nucleus. 

What is commonly understood by a fundamental approach is applying theoretically based mathematical models of necessary equipment items. Intrinsic (not falsified by processes other than a chemical transformation) kinetics of all processes are investigated, transport phenomena are studied, flow patterns are identified, and relevant microscopic phenomena are studied. It is intended to separately study as many intrinsic stages as possible and to combine results of these investigations into a mathematical model. Such a model contains only a limited amount of theory (grey models, gross models, or tendency models). Obviously, the extrapolation power of these models strongly depends on the content of theory. The model... 

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