Life Sciences Commons^™

Divergent-Beam X-Ray Diffraction In The Scanning Electron Microscopy And Its Use For The Study Of The Semiconductor Epitaxial Layers, J. Hejna

Scanning Electron Microscopy

Among the X-ray techniques belonging to the family of Kassel methods the divergent-beam diffraction method gives the best contrast for semiconductor specimens.

The technique has been accomplished in the scanning electron microscope (SEM) in a back reflection configuration. Epitaxial layers of GaAsSb and GaAsSbP on GaAs [100] oriented substrates were investigated. The diffraction lines from lattice planes giving only high Bragg angles were used. For the purpose of the layer strain analysis, the diffraction experiments were carried out for specimens placed horizontally (the lines {711} type recorded) and for tilted 45° (the lines {551) type recorded). A Cu foil was …

The Application Of Physico-Chemical Procedures In The Analysis Of Urinary Calculi, Allen L. Rodgers

Scanning Electron Microscopy

All physico-chemical techniques used in the analysis of urinary calculi have inherent advantages and limitations. Al though x-ray powder diffraction can identify constituents unambiguously, certain minor components can be missed. Infrared spectroscopy is more sensitive but band assignment at low concentrations is difficult. Scanning electron microscopy together with energy dispersive x-ray analysis permits the simultaneous investigation of morphology and chemical microstructure. However, microanalysis of elements lighter than sodium is not possible and constituents are prone to irradiation damage. With the electron microprobe, minor constituents can be detected but tedious sample preparation procedures are required. Transmission electron microscopy is extremely useful …

Ultrastructural Studies Of Crystal-Organic Matrix Relations In Renal Stones, P. -T. Cheng, A. D. Reid, K. P. H. Pritzker

Scanning Electron Microscopy

Biochemically the organic matrix of kidney stones contains mucoproteins, mucopolysaccharides, inorganic material and bound water. Morphologically, the organic matrix exists as either amorphous or fibrous forms. We have attempted to critically evaluate results from analytical and morphological studies on stone matrices using light microscopy, histochemistry, x-ray diffraction, scanning electron microscopy, x-ray energy dispersive spectrometry, transmission electron microscopy and selected area electron diffraction.

On the surface of calcium oxalate stones, there are usually large masses of randomly deposited calcium oxalate crystals each coated with organic matrix. Transmission electron microscopy shows these large surface crystals are composed of rows of smaller crystallites …

Relation Between Microstructure, Destabilization Phenomena And Rheological Properties Of Whippable Emulsions, W. Buchheim, N. M. Barfod, N. Krog

Food Structure

The structure of spray-dried whippable emulsions (toppings) containing different types of lipid surfactants, was investigated by electron microscopy using the freeze-fracture technique. The size distribution of the lipid particles within the powders varied with the type of the surfactant used. After reconstitution of the topping powders in water. a strong destabilization phenomenon took place to an extent depending on the type of the surfactant. Simultaneously a crystallization of coalesced lipid particles occurred along with an increase in viscosity of the emulsions. The degree of crystallization was measured by p-NMR. It has been concluded that these phenomena are closely related to …

Combining Microscopy And Physical Techniques In The Study Of Cocoa Butter Polymorphs And Vegetable Fat Blends, J. D. Hicklin, G. G. Jewell, J. F. Heathcock

Food Structure

Transmission electron microscopy, differential scanning calorimetry and X-ray diffraction have been used to study the cocoa butter polymorphs and blends of cocoa butter with a hydrogenated vegetable fat. The results indicate the presence of six polymorphs and confirm observations made by other workers. Vegetable fat addition affects both the molecular structure and the morphology of the crystals observed. After temperature cycling, a blend containing 50% vegetable fat developed two crystal types and differences in the X-ray pattern were apparent. Correlations could be made between the known molecular structure and the morphology observed in most of the polymorphs. In selected cases, …

Particle Structure In Spray-Dried Whole Milk And In Instant Skim Milk Powder As Related To Lactose Crystallization, Zenichi Saito

Food Structure

The structure of instant skim milk and whole milk powders was studied by scanning electron microscopy with special respect to lactose crystallization during storage. X-ray diffraction analysis was used to confirm the crystallization. Some samples were ashed in a plasma asher and the residues were also examined by scanning electron microscopy. The structures of instant skim milk and whole milk powder particles were well-preserved after the ashing procedure.

The crystallization of ~X-Iactose hydrate occurred in instant skim milk and whole milk powders according to moisture uptake. In instant skim milk powder, ~X-Iactose hydrate crystals were observed on the particle surface. …

Demonstrable Fixative Interactions, Keith M. Meek, John A. Chapman

Scanning Electron Microscopy

Electron-optical examination of reconstituted collagen fibrils fixed with tannic acid and/or glutaraldehyde and positively stained with heavy metal anions and cations reveals distinct changes in the high resolution staining patterns seen in TEM. Correlation with the known sequence data demonstrates that these changes are caused by (a) interaction of the fixative with certain charged groups in the collagen and (b) localized stain-exclusion effects following fixation. We have analysed the positive and negative staining patterns from glutaraldehyde-treated collagen in detail. In positive staining, uptake of staining ions is shown to be inhibited not only at residues known to interact with glutaraldehyde …