Search

A new approach has been made to the study of some cases of tropical elephantiasis, using transmission and scanning analytical electron microscopy, in conjunction with X-ray diffraction analysis, emission spectroscopy, microincineration, and various histological techniques. Hitherto undescribed accumulations of inorganic materials, particularly silicon and aluminium, have been located in lymph nodes draining affected areas. It is postulated that these elements, either directly or in conjunction with other factors, are responsible for the onset of some types of swollen leg.

SUMMARY Detailed analysis of thin oxide films is providing a better understanding of the mechanisms of oxidation and corrosion. The analytical electron microscope used to study thin layers on iron-chromium alloys has shown that even after oxidation times as short as 10 min at 600°C the ratio of iron to chromium in the surface oxide will be different from that in the underlying alloy and discrete nodules may well have a higher iron content than the protective film in which they are growing. Progressive changes in different morphological features of the oxide films grown at varying times and temperatures can be followed by micro-probe analysis in EMMA 4. Results obtained from the oxidation in air of iron with 10% and iron with 20% added chromium are presented.

SUMMARY Some metallurgical studies carried out using a combined electron microscope — microanalyser (EMMA-3) are described. A correction procedure is outlined for the quantitative X-ray microanalysis of thin foils and small extracted particles. The applications discussed include (a) the examination of small crystals of carbides and spinel-type oxides, (b) the analysis of small, single-phase grains in splat-quenched Al-8%Fe, and (c) the identification of small ferrite grains within an austenite matrix by means of the convergent-beam diffraction technique.

SUMMARY A routine method is described for X-ray microanalysis of thin specimens of biological tissue containing mineral particles in cancerous growths. Such a method allows information to be obtained that relates pathological history to histology, electron microscopy and X-ray microanalysis. Classification of minerals is possible in a way that is not provided by bulk analysis. The technique provides baselines of elemental data of minerals from various sources that may be used to classify particles found present in certain tumour growths.

The difficulties associated with the study of naturally occurring and foreign crystals or particles of hard material in biological tissues are well known. By means of an extraction-replication technique, material of this kind can be subjected to microanalysis without the need for fixation, embedding or staining. Reference is also made to the uptake and detection of gold in lysosomes.

Foot-and-mouth disease virus, type A, strain 119, (FMDV-A 119) was purified from infectious tissue culture fluid, bovine vesicular fluid, and tongue epithelium and identified by analytical electron microscopy as a particle approximately 23 mμ in diameter. In addition, a smaller particle (8 ± 2 mμ) closely associated with the virus particle, particularly in animal-derived material, was found in centrifugally-separated fractions which possessed complement-fixing activity.

SUMMARY Recent years have seen the way in which the analytical electron microscope has been applied to problems involving thin specimens in metallurgy, mineralogy and many branches of biology. The limits of sensitivity have been explored and its potential usefulness in these fields investigated. Problems concerning the interaction of electrons with the specimen are discussed in relation to the correct choice of operating conditions and specimen preparation. In biological work, frozen sections provide new information about subcellular elemental localization of mobile electrolytes, while analysis of tissue prepared by conventional means is used to detect physiological levels of some naturally occurring elements. Examination of mineral dispersions provides analysis of particles just 10 nm thick, visible only in transmission electron microscopy, and further work with thin metal foils confirms the value of high resolution transmission imaging as a complementary facility to micro-analysis. Work has been done to investigate the possibilities of improving sensitivities both by changing operational parameters and instrumental design, and the value of quantitation in thin specimen analysis explored.