Digital Commons Network^™

Electron Energy Loss Spectroscopic Imaging In Biology, G. T. Simon, Y. M. Heng

Scanning Microscopy

One of the goals in biology is to relate the ultrastructure with the movement of elements to under stand better physiological and pathophysiological mechanisms. Electron energy loss spectroscopy (EELS) imaging, which was developed in the last decade, appears to be an ideal technique to make such correlation.

EELS takes advantage of the energy distribution of transmitted electrons which interacted with the specimen. All these electrons are collected and can be displayed as an energy loss spectrum for analytical purposes. Images can be produced from selected regions from the energy distribution allowing the mapping of specific elements. The main advantage of …

Inflation And Productivity In The United Kingdom: An Empirical Note, Peter J. Saunders, Basudeb Biswas

Economic Research Institute Study Papers

The escalating inflation in the second part of the 1970s and the early 1980s has revived interest in the theoretical relationship between inflation and the growth of productivity. The standard theoretical view maintains that the unidirectional flow of causality runs from productivity changes to inflation. It assumes that productivity growth is exogenous, and that positive productivity growth is anti-inflationary because it increases the economy's aggregate supply, which in turn offsets the inflationary pressure. An obvious implication of this view is that the inflation rate could be reduced through productivity growth.

Scanning Electron Microscopy - Electron Beam Induced Current And Deep Level Transient Spectroscopy Studies Of Gaas(In) Layers Grown By Molecular Beam Epitaxy, Y. J. Huang, Dimitris E. Ioannou, A. Iliadis

Scanning Microscopy

Electrically active defects in indium-doped (0.6%) GaAs layers grown by Molecular Beam Epitaxy (MBE) on Si-doped (≈1x10¹⁸ cm^-3) GaAs substrates have been studied by the combination of two techniques: Scanning Electron Microscope - Electron Beam Induced Current (SEM-EBIC) technique, and Deep Level Transient Spectroscopy (DLTS). The epilayers studied were three microns thick. No electrically active defects were revealed by the EBIC micrographs in the top one micron of the epilayers, whereas a large number of non-propagating misfit dislocations were observed at the epilayer/substrate interface. DLTS measurements made in the dislocation free top region of the epilayer showed …

Scanning Microscopic Observations On Dental Caries, Sheila J. Jones, Alan Boyde

Scanning Microscopy

This paper presents findings made using special techniques of imaging and/or of specimen preparation to investigate the changes in tooth structure which occur in caries. We have studied both coronal and root caries in enamel, dentine and cementum using scanning electron and confocal scanning optical microscopy.

In preparation for backscattered electron (BSE) imaging in the SEM, teeth were stored in 70% ethanol until further dehydration in ethanol and embedding in polymethylmethacrylate (PMMA). Longitudinally cut surfaces were diamond polished and coated with carbon or silver before BSE imaging. Important changes in the distribution of densities in both enamel and dentine occurred …

Image Analysis And X-Ray Microanalysis In Cytochemistry, W. C. De Bruijn, H. K. Koerten, M. I. Cleton-Soeteman, C. J. G. Blok-Van Hoek

Scanning Microscopy

When cytochemical reaction products are homogeneously distributed within an organelle, point analyses suffice for the quantitative approach. However, quantitative analysis becomes tedious, when the elements in the reaction product are inhomogeneously distributed. Problems arise when elements from two reaction products have to be related to each other, or to endogenous cytological products (ferritin, haemosiderin, calcium, electron dense markers), either topographically or in concentration. When analyzing inhomogeneous/heteromorphical reaction product-containing organelles special attention has to be paid to measure and relate both volume and concentration. In this paper a relative simple structure (eosinophil granules) is chosen to demonstrate that the acquisition of …

Scanning Electron Microscopy Of Burnt Electric Wires, R. P. Singh

Scanning Microscopy

Aluminium and copper wires were burnt by electric short circuit and by outside flame. These wires have been studied under scanning electron microscope with a view to distinguish them in fire cases. It was observed that there were extensive grains on the cylindrical surfaces near the ends of copper wires burnt by electric short circuit. The grainy structures were continuously decreasing with distance from the ends and vanished. Aluminium wires had bucklings starting from the ends and decreasing on subsequent portions. These features were found to have a potential advantage to identify the ends specially those which did not have …

Industrial Problem Solving With Microbeam Analysis, Klara Kiss

Scanning Microscopy

The objective of this paper is to provide an overview of the microbeam analytical techniques and to help select the appropriate one to solve complex problems often arising in today's high - tech industries. case histories are given to show how renowned analytical service laboratories and microbeam experts formulated their strategies to approach a real life problem, what type of conclusions were deduced from the data and, finally, how the problem was solved.

Numerical Approaches To Non-Destructive Depth Profiling By Variable Angle X-Ray Photoelectron Spectroscopy, P. C. Mccaslin, V. Young

Scanning Microscopy

Variable angle x-ray photoelectron spectroscopy (VAXPS), also known as angle-resolved x-ray photoelectron spectroscopy (ARXPS), is a method which can be used to depth profile the near surface region non-destructively. The intensity variation with angle of a given energy level in a sample contains the complete information about the concentration profile of the photoionized component in the depth probed. It has been shown that the intensity is the Laplace transform of the concentration profile. Theoretically it should be possible to uniquely determine the concentration profile as the inverse Laplace transform of the intensity data. After a brief background sketch, the numerical …

Evolutionary Aspects Of Reptilian And Mammalian Enamel Structure, A. Sahni

Scanning Microscopy

The evolution of enamel structure is dealt with here on the basis of fossil reptiles and mammals ranging from the Triassic to the present. The evidence suggests that prismatic enamel had developed in some therapsid reptiles and the mammal, Eozostrodon about 180 million years ago. For the next 100 million years, mammalian evolutionary history is sparingly documented and this is reflected in the poor record of enamel evolution during this period. The few Jurassic reptiles and mammals studied suggest a pre-prismatic structure. In the Late Cretaceous (BO to 65 million years ago) when the fossil record improves, mammalian enamel investigated …

Optical Emission And Laser Spectroscopy In Studies Of Sputtering: Actual Research Activities And Recent Achievements, W. Husinsky, G. Betz

Scanning Microscopy

Laser Spectroscopy has been developed into a powerful tool for the detection and energy analysis of neutral particles. Laser Induced Fluorescence Spectroscopy (LIF) has yielded a wealth of information about sputtered neutral particles. In addition, Laser Ionization Spectroscopy has recently offered an increased detection sensitivity. In this paper a summary of recent results is given. By combining LIF with other methods capable of measuring densities and energy distributions of sputtered excited atoms in short lived states, new information about sputtering and excitation mechanisms have been recently obtained and will be summarized here.

Proton Energy Loss Spectroscopy For Surface Monolayer Analysis, Noriaki Matsunami

Scanning Microscopy

A survey is given of recent advances in the use of high-energy proton backscattering spectroscopy or proton energy loss spectroscopy (PELS) under the glancing incidence geometry for monolayer-sensitive analysis. Two theories of the energy loss involved in the PELS are described, based on the continuous and impact parameter dependent slowing down models. The latter theory leads to the azimuthal angle dependence of the energy loss. It is also shown that this technique is applicable to underlayer composition analysis

Analysis Of Thick Targets By Proton-Induced X-Ray Emission, J. L. Campbell, A. Perujo, W. J. Teesdale, J. A. Maxwell

Scanning Microscopy

Most published PIXE (proton-induced X-ray emission) work concerns thin targets. Recently progress in improving both the fundamental data base and in developing a range of standardization techniques has propelled thick target analysis to the forefront of activity in the PIXE field. Limits of detection are a complex issue depending not only on the continuous background but also on the characteristic X-rays of the matrix; in favorable cases a few ppm may be reached in convenient analysis times. The unfolding of multi-element PIXE spectra is akin to the same problem in EPMA (electron probe microanalysis), and EPMA methodologies, especially as regards …

Microvascular Corrosion Casting Of The Lung. A State-Of-The-Art Review, Dean E. Schraufnagel

Scanning Microscopy

Corrosion casting and viewing of replicas with the scanning electron microscope is an excellent way to study the microvascular structure of the lung. This method can demonstrate aspects of the three-dimensional relationships, branching patterns, maximum diameters, arterio-venous connections, unusual sized and shaped capillaries, development and growth, neovascular structures and changes in development and disease better than any other means. Comparisons can be made in many experimental conditions and fundamental information obtained to answer physiologic questions. This paper reviews how the lung microvasculature has been studied by corrosion casting and scanning electron microscopy and indicates new areas where investigation might be …

1987 Annual Meeting, Various Authors

Annual Reports

No abstract provided.

Secretory Ameloblasts And Calcium Distribution During Normal And Experimentally Altered Mineralization, S. H. Ashrafi, Dale R. Eisenmann, A. E. Zaki

Scanning Microscopy

The distribution of calcium in relation to secretory ameloblasts of the rat incisor was studied. An experimental model system in which enamel mineralization was temporarily inhibited by injecting sodium fluoride and cobalt chloride was used. Potassium pyroantimonate (PPA) cytochemistry, electron energy loss spectroscopy (EELS), and energy dispersive X-ray spectrometry (EDS) were used to clarify the role of the ameloblast in controlling calcium distribution during normal and experimentally altered enamel mineralization.

Secretory ameloblasts chemically-preserved in glutaraldehyde either with or without PPA were analyzed for calcium; those preserved with PPA showed higher concentrations of calcium than did those preserved with glutaraldehyde only. …

Photocleave – A Method For Nondestructive Sectioning Of Photoresist Features For Scanning Electron Microscope Inspection, D. E. Schrope

Scanning Microscopy

A simple nondestructive method of photolithographically sectioning resist features is presented. The method utilizes the superposition of the normally exposed device features followed by a second exposure of a long wide linear feature, all before the development step. The superposition results in a precise and clean cross-sectioning of the feature, allowing inspection of line-edge profiles and contact windows in addition to measurements at the crucial substrate-resist interface.

An Algorithm For On-Line Digital Image Processing For Assisting Automatic Focusing And Astigmatism Correction In Electron Microscopy, Norio Baba, Eisaku Oho, Koichi Kanaya

Scanning Microscopy

An algorithm for processing a diffractogram of an electron image input by an on-line system has been improved, with the aid of projection theory, so as to achieve real time operation. This algorithm can, therefore, automatically focus in scanning electron microscope, and correct for the astigmatic aberration of both transmission and scanning electron microscopes by analyzing the spectrum computed from the diffractogram. Experimental results show that this algorithm is effective for detecting the amount of defocus and astigmatism in both transmission and scanning electron microscopes.

Characteristics Of An Electric/Magnetic Quadrupole Detector For Low Voltage Scanning Electron Microscopy, M. Brunner, R. Schmid

Scanning Microscopy

The electric/magnetic quadrupole detector allow's efficient detection of secondary electrons in low voltage scanning electron microscopy without introducing disturbing aberrations. The original detector of this type was built in 1986; it has now been equipped with scintillator-photomultiplier assemblies on both positive electrodes. Their signals, A and B, can be combined to A+B or A-B, thus enhancing or suppressing different types of contrast. The aberration disc produced by the present design of detector was estimated to have a diameter of 10 nm. Experimentally, no deterioration of image resolution was observed. The collection efficiency was predicted to be 26% and can be …

Quasi-Elastic Scattering Studies Of Water Diffusion, H. E. Rorschach, D. W. Bearden, C. F. Hazlewood, D. B. Heidorn, R. M. Nicklow

Scanning Microscopy

Quasi-elastic neutron scattering is a powerful method to study the dynamics of protons in biological systems. The technique has been used both for the study of water diffusion and protein motion. The neutron scattering measurements on water show that the translational and rotational diffusion coefficients in biological systems are reduced from bulk values. We review the measurements on water in frog muscle, cysts of artemia, and phycocyanin. Measurements on dry trypsin and trypsin-D₂O solutions over the temperature range 75-300K show that there is proton motion at the one angstrom level even in the dry or frozen state.

Secondary Electron Emission Induced By Electron Bombardment Of Polycrystalline Metallic Targets, R. Bindi, H. Lanteri, P. Rostaing

Scanning Microscopy

The aim of the present paper is the analysis of the backward secondary electron emission phenomenon, under electron bombardment, on the basis of experimental and theoretical results. Among the theoretical models, we will mention the phenomenological models, those which use a Monte-Carlo type simulation method, and those based on the numerically solved Boltzmann transport equation.

To correlate experimental and theoretical results on all the data characterizing this phenomenon, it is necessary to use an appropriate description for the excitation process of the internal secondary electrons; it also needs a complete description of the transport process for the excited electrons, which …

External Shape Of Enamel Crystals, H. Warshawsky

Scanning Microscopy

Biological hydroxyapatite crystals are either small, as in bone and dentin, or large as in enamel. Enamel crystallites are unique since each is initiated and grows in length, thickness and width until the entire layer of enamel is secreted. In maturation, these extremely long crystallites grow only in thickness and width. Crystal growth in vitro follows physico-chemical principles, but lacks biological intelligence; in vivo this intelligence is contributed by protein templates. The location of the organic template in enamel is congruent with the crystallite, constituting the crystal ghost. Since crystals cannot accommodate proteins, the explanation is logically inconsistent. In sections, …

Expert Potentiometric Surface Modification For Groundwater Contaminant Management, R. L. Ward, Richard C. Peralta, J. R. Brashar

Civil and Environmental Engineering Faculty Publications

An expert system is linked to an previously reported optimization program. The expert system prompts the user for information about a groundwater contamination problem. The expert system determines whether pumping is a suitable containment strategy. If appropriate. it selects several well arrangements to be evaluated by an optimization algorithm.

Advanced Vacuum Systems For Analytical Electron Microscopy, G. S. Venuti

Scanning Microscopy

Recent technological advancements such as significantly improved power supply stability and polepiece design, as well as increased accelerating voltage all contribute to the primary objective of the scanning electron microscope (SEM): higher resolution. Similarly, the advent of analytical electron microscopy (AEM) has also expanded the scope of applications to include energy-dispersive spectrometry, wavelength-dispersive spectrometry, and electron probe analysis. Specimen contamination and damage has become increasingly problematic as SEMs are used as analytical instruments. In an effort to minimize contamination and etching, and thereby benefit from these advances, cleaner and more efficient vacuum systems are required. Such benefits were realized when, …

Preservation Of In Vivo Morphology Of Blood Vessels For Morphometric Studies, Robert M. K. W. Lee

Scanning Microscopy

Preservation of in vivo morphology of the blood vessels is important for morphometric studies. With each fixation method (e.g., immersion fixation, perfusion fixation), there are inherent pitfalls which can easily distort vessel wall morphology, thereby creating artifacts. Alteration of the vessel wall cell volume due to tissue preparation is another common source for errors. Selection of proper morphometric protocols for comparative studies is crucial. Lack of attention in these areas is a cause of confusion and contradiction in the literature. In this review, the merits of various commonly used methods for vessel wall preparation and measurements are discussed.

Analysis Of Clean Transition Metal Surfaces By Core Level Spectroscopy, M. C. Desjonquères, D. Sébilleau, G. Tréglia, D. Spanjaard, C. Guillot, D. Chauveau, J. Lecante

Scanning Microscopy

The shifts in the binding energy of core electrons detected by high resolution X-ray photoelectron spectroscopy are a very sensitive probe of the chemical bonding of the excited atom. Since the surface atoms have their geometrical environment perturbed, their core levels are shifted from their bulk positions. A very large number of experiments have been performed on the 4f core level positions of tantalum and tungsten for various orientations of the surface plane. Systematic trends have been put forward and explained by theoretical models. Furthermore, the analysis of the angular variation of the core level line intensities gives structural information …

The Fine Structure Of The Human Placental Villus As Revealed By Scanning Electron Microscopy, G. J. Burton

Scanning Microscopy

Scanning electron microscopy of the placenta has a history of only twenty years. During that time, however, there have been dramatic advances in instrument technology coupled with the refinement of preparative techniques designed to reduce fixation artifacts to a minimum. As a result many of the early claims must be amended or suitably qualified, and this is one aim of the present review.

Much new data on the internal structure of the placental villus is also presented. By means of the partial digestion technique it is now possible to describe the three dimensional configuration of the various components of the …

Electron Microprobe Analysis And Proton Induced X-Ray Spectrometry Applied To Trace Element Analysis In Sulfides: Problems And Prospects, G. Remond, F. Cesbron, K. Traxel, J. L. Campbell, L. J. Cabri

Scanning Microscopy

The complementary techniques of EPMA and micro-PIXE are reviewed in the context of spatially resolved trace element analysis of sulfide minerals. Attention is focussed on methods of standardization and of fitting EDX spectra. Sphalerites and chalcopyrites from various sources are used as specimens. For Ag in chalcopyrites, the two techniques agree well. Sphalerites pose problems such as Zn-Fe replacement and the presence of minor elements, both of which influence matrix corrections ; these are addressed in detail. The necessity for absorbers in the micro-PIXE work prevents detection of minor elements lighter than Zn ; these are determined by EPMA and …

Interpretation Of Electron Micrographs, B. A. Afzelius

Scanning Microscopy

Courses in electron microscopical techniques should include training in the active reading of electron micrographs. The student should be made aware of the fact that every micrograph contains a wealth of information, evident and hidden, and that a careful inspection is required to retrieve the information. More time should normally be spent in scrutinizing the micrograph than in its manufacture. Active reading of the micrograph is aided by a curiosity in the functional significance of the various details of the picture; there has to be a dialogue between the mind and the eye concerning the structural elements and their significance. …

Scanning Transmission Ion Microscopy As It Complements Particle Induced X-Ray Emission Microanalysis, H. W. Lefevre, R. M. S. Schofield, J. C. Overley, J. D. Macdonald

Scanning Microscopy

The early uses of Scanning Transmission Ion Microscopy (STIM) with MeV ions are reviewed. The transformation of STIM energy-loss images into maps of areal density is discussed, and is illustrated with images of a fruit fly head (Drosophila melanogaster). Freeze-dried male heads are transparent to 4-MeV protons in the dorsal and frontal directions, but in the sagittal direction the brain is opaque. STIM with molecular ions is shown to be useful for increasing contrast in low density areas. For recording registered STIM and PIXE images without changing accelerator parameters, apertures are used to accomplish the required change in beam intensity …

Ultrastructural Analysis Of Dynamic Cellular Processes: A Survey Of Current Problems, Pitfalls And Perspectives, Helmut Plattner, Gerd Knoll

Scanning Microscopy

Dynamic phenomena in cells that can be analyzed on the ultrastructural level comprise so different aspects as ion shifts, conformational changes of macromolecules, membrane particle rearrangements, lipid phase transitions, protein--protein interactions (notably ligand-receptor interactions, including their sorting and sequestration), reversible membrane-to-membrane contacts, membrane fusions, transcellular transport phenomena, restructuring of cytoskeletal elements, ciliary and flagellar beat, cell shape changes, etc. Only some of these phenomena can be analyzed under stationary conditions, while others are unidirectional and sometimes very rapid. Therefore, the methodical approaches to be used (primary methods and follow-up procedures) might be widely different. Quite different methods are available, such …