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A technique is proposed for X-ray electron-probe microanalysis (EPMA) of individual particles of solid snow sediment. Two sample preparation procedures were used to analyze the sediments. The PAP-method and the original bi-exponential model were used for matrix correction and the calculation of elemental composition. A method of calculating composition has been developed for approximately spherical...
Vitellin polypeptides are proteolytically processed in ovarian follicles and embryos of the stick insect Carausius morosus. Data show that vitellin polypeptide A 3 of 54kDa is processed to yield polypeptide A 3* of about 48kDa upon completion of ovarian development, whereas vitellin polypeptide A 2 of 90kDa yields polypeptide E 9 during embryonic development. As...
In the secondary hardening reaction in ultrahigh strength steel of high Co-Ni alloy, the needle-shaped precipitating carbide is the main strengthening phase. Particular attention has been paid to the nucleation, growth and coarsening of the precipitate and its interface with the ferrite matrix. High resolution transmission electron microscopy observations show that when tempered at a low temperature...
We have fabricated a cryogenic atomic force microscope that is designed for structural investigation of freeze-fractured biological specimens. The apparatus is operated in liquid nitrogen gas at atmospheric pressure. Freeze-fracturing, freeze-etching and subsequent imaging are carried out in the same chamber, so that the surface topography of a fractured plane is easily visualized without ice contamination...
The 18.5kDa isoform of myelin basic protein (MBP) has strong and probably specific interactions with phosphoinositides that are of interest regarding this protein's function, and in effecting its two-dimensional crystallization for structural determination. We have designed and constructed truncation mutants of recombinant 18.5kDa murine myelin basic protein (rmMBP) lacking either the N- or C-terminal...
Scanning electron microscopy revealed that-as is common in this family of the Hemiptera-the eggs of the green stink bug Acrosternum (Chinavia) marginatum are roughly barrel-shaped and possess at their apical pole a row of slender extensions, the aero-micropylar processes. The outer surface of the eggshell carries hexagonally arranged pits. The analysis of cross-fractured eggshells showed that the...
Energy filtering transmission electron microscopy (EFTEM) has become one of the most efficient tools for specimen characterization at nanometer length scales. EFTEM imaging is most often carried out in the core-loss region but image intensity becomes more and more a limiting factor with decreasing feature size. Alternatively, it is possible to record EFTEM images in the low-loss region, where intensities...
Artifacts associated with transmission electron microscope (TEM) specimens prepared using a focused ion beam (FIB) are not well understood, especially those in non-semiconductor materials. In this paper the extent and origins of artifacts associated with redeposition of milled material in TEM specimens of a FeAl-WC metal matrix composite prepared by FIB were investigated. Cross-sections were prepared...
In this paper, we present a system developed to identify metal nanoparticles at different orientations, using digital image processing and analysis. The correct identification is important in nanotechnology, where it is possible to build structures for different purposes at the nanometric level. The recognition system computes automatically different characteristics such as: nanoparticle area, polygons,...
In this paper we describe a novel method to prepare powder specimens for transmission electron microscopy examination. The powder samples are embedded in a metallic matrix by a route based on the plastic flow of a soft metal, using a small laboratory type hand driven hydraulic press. The resulting composites are processed with the conventional procedure based on grinding polishing and ion beam milling...
Superconducting MgB 2 ceramics were prepared and yield superconducting transition temperatures of about 39 K. For covering the various length scales on which inhomogeneities appear in MgB 2 , electron-probe micro-analysis (EPMA) and analytical transmission electron microscopy (TEM) were applied for a phase analysis. Particularly useful were the preliminary electron spectroscopic imaging...
From an EM study of thin sections, the rod-like microneme organelles within conventionally glutaraldehyde fixed Cryptosporidium parvum sporozoites have been shown to undergo a shape change to a more spherical structure when the sporozoites age in vitro for a period of ~12 to 24 h. This correlates with the shape change of intact sporozoites, from motile hence viable thin banana-shaped cells to swollen...
Reflections forbidden under the single scattering approximation are not expected to remain extinct for crystal thicknesses for which multiple scattering becomes important, except for reflections of the Gjonnes-Moodie type. However, it has been observed that in many crystals with the incident beam along a zone axis, such as diamond-like crystals along the [110] zone, reflections forbidden under the...
The electronic structure of hexagonal GaN is studied using two simulation techniques in order to develop a method to interpret the fine-structure of an experimental nitrogen K-edge electron energy loss spectrum obtained using a scanning transmission electron microscope. The application of these simulation methods to the bulk spectrum is a necessary first step in developing a fundamental understanding...
This article is a survey of hardware and software advances that promise to increase the power and sensitivity of electron energy-loss spectroscopy (EELS) and energy-filtered imaging (EFTEM) in a transmission electron microscope. Recent developments include electron-gun monochromators, lens-aberration correctors, and software for spectral sharpening, spectral processing and interpretation of fine structure...
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