Biology Commons^™

Sputter Crater Contour Mapping With Multilayered Films, L. L. Levenson, T. P. Massopust, J. Dick, M. C. Jaehnig, D. Griffith

Scanning Electron Microscopy

Multilayered films composed of alternating 200 Å Al and 267 Å Al203 layers are made by physical vapor deposition. Twenty-two pairs of these films are deposited on a polished Si wafer. Ion beam sputtering is used to form craters in the multilayered film. When a crater is viewed or photographed in situ by scanning electron microscopy, the Al₂O₃ layers appear bright and the Al layers appear dark. In the scanning electron microscope (SEM) the Al₂O₃ layers have a high secondary electron yield compared to Al. In secondary ion mass spectrometry (SIMS), using Cs^{+ …}

The Endothelium Of Initial Lymphatics During Postnatal Development Of The Rat Tongue, A. Castenholz

Scanning Electron Microscopy

The luminal surface of the subepithelial lymphatic plexus in the tongue of rats was investigated with SEM at different stages of postnatal development. In newborn and infant animals prominent and branched endothelial cells exhibit a conspicuous phenomenon producing a very irregular inner profile of the vascular wall. Among these cells the spindle-shaped type proves to be an essential component of the valve structures already found in few-day-old animals. There are also prominent cells with a polygonal appearance resembling histioblasts which form with their manifold processes, that partly extend into the lumen, an interlacing cellular pattern. The special morphological characteristics of …

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 …

Secondary Electron Imaging In The Scanning Transmission Electron Microscope, R. M. Allen

Scanning Electron Microscopy

The detailed correlation of surface morphology and subsurface microstructure has been made possible by the scanning transmission electron microscope. This instrument provides the capability for simultaneous and independent secondary electron and transmitted electron imaging from the same sample area. This includes the ability to generate mixed secondary/transmitted electron images, which form a concise visual presentation of the information in the two component images.

Correlative surface and through-volume specimen examination of this type has most frequently been applied to backthinned samples, which are specifically prepared in a way which produces electron-transparent material in the immediate vicinity of a surface of interest …

Applications Of Laser Microprobe Mass Analysis For Characterization Of Asbestos, J. K. De Waele, F. C. Adams

Scanning Electron Microscopy

Laser microprobe mass analysis with the commercial LAMMA-500 (transmission type) instrument when utilized in laser desorption conditions provides information which allows the identification of particular asbestos varieties, in various types of samples, including lung tissue. Also it has detection capability of adsorbed organic material and it is a valuable tool for the study of the surface of chemically modified asbestos fibers manufactured by silanation or through phosgene treatment (chrysophosphate). Recent progress within our laboratory is discussed, and shortcomings of the methodology are indicated.

Implantation Failure Of Peritoneal Dialysis Catheters: A Scanning Electron Microscopical Study, D. W. Gregory, G. G. Youngson, D. Marshall

Scanning Electron Microscopy

Patients with end stage renal failure may be treated by continuous ambulatory peritoneal dialysis. The transcutaneous portion of the catheters used in this treatment is covered with porous expanded polytetrafluoroethylene (PTFE) to provide a surface suitable for tissue infiltration. Following some instances where catheters failed to become fixed in the abdominal wall, a scanning electron microscopical study was carried out to compare the infiltration of catheters having successful or unsuccessful implantation.

The porous layer of a well-fixed catheter, removed after successful renal transplantation, was infiltrated with collagen fibrils and overlain by layered connective tissue composed of fibroblasts and collagen fibre …

X-Ray Microanalysis Of Urinary Stones, A Comparison With Other Methods, K. M. Kim, H. B. Alpaugh, F. B. Johnson

Scanning Electron Microscopy

A previous study of urinary stones by a combined electron microscopy demonstrated the potential of scanning electron microscopy and X- ray analysis as an analytic tool for urinary stones. Electron diffraction was chosen for the final confirmation of crystals in the study. Although electron diffraction is highly accurate for this purpose, it is desirable to establish the sensitivity of X-ray analysis for the identification of stone components relative to the more commonly used methods. Eighty six consecutive urinary stones were analyzed by X-ray analysis and the findings were compared with those of X-ray diffraction, infrared spectrometry and chemical analysis. The …

Delineation Of Emitter-Collector Shorts In Bipolar Test Structures By Voltage Contrast Scanning Electron Microscopy, A. H. Carim, R. Sinclair, W. T. Stacy

Scanning Electron Microscopy

In examining emitter-collector shorts and their relationship to structural defects, we desire a nondestructive method for locating the short-circuited devices in large test arrays. Voltage contrast scanning electron microscopy (VC-SEM) and an established electrochemical anodization technique have been used to identify electrically faulty bipolar transistors. Direct comparison of these approaches was achieved by examining the same emitters with each method. The results indicate that VC-SEM may serve as a useful technique for delineating E-C shorts because of its nondestructive and purely electrical nature. In our qualitative investigation, the sensitivity and voltage resolution available by VC-SEM were not sufficient to differentiate …

Ion Discrimination Effects In The Laser Microprobe Mass Analyzer, Eric Michiels, Marc De Wolf, Renaat Gijbels

Scanning Electron Microscopy

Different discrimination effects have been observed for atomic and polyatomic cluster ions when varying the ion lens potential of the laser microprobe mass analyzer. This is attributed to the chromatic aberration of the einzel lens, leading to different effects on ions with different energy distributions. Ion kinetic energy distributions were measured using the cut-off property of an ion reflector. The energies of elemental ions are higher and the energy distributions broader than those of polyatomic ions. Chemically different ion species have different energy distributions. An attempt is made to correlate the instrumental effects with results from ray tracing computer programs.

Collagen Deposition During Wound Repair, Charles J. Doillon, Michael G. Dunn, Richard A. Berg, Frederick H. Silver

Scanning Electron Microscopy

Collagen fiber diameters, amount of birefringent collagen (brightness) and birefringence retardation were measured in implanted collagen-based sponges containing hyaluronic acid (HA) and fibronectin (FN). In the presence of HA and FN, increased number of fibroblasts and brightness were observed 6 days after wounding. Increased brightness in the presence of HA and FN reflected increased deposition of oriented collagen fibers. From days 9 to 12, increased fiber diameters were similar in implanted collagen-based sponges with or without HA and FN. Increased birefringence retardation in sponges containing HA and FN was consistent with increased packing density of collagen fibers observed by scanning …

Amphibian Lampbrush Chromosome Loops: Correlative Light Microscopy, Transmission Electron Microscopy, And Scanning Electron Microscopy Observations, M. L. Bonnanfant-Jais, E. N'Da, M. Penrad-Mobayed, N. Angelier

Scanning Electron Microscopy

The RNP matrix of landmark loops in Pleurodeles waltlii lampbrush chromosomes have been examined by light microscopy, transmission and scanning electron microscopy. This study shows that in normal loops as well as granular, globular and dense loops, the RNP matrices are composed of one basic structure: an RNP particle with a diameter of 30 nm. The scanning electron microscope study also clarified the spatial arrangement of the various types of RNP matrices. The specific morphology of the RNP matrices is due to i) the progressive packaging of transcription products and ii) a concomitant and gradual coiling of the loop axis.

Approach To A Stable Field Emission Electron Source, H. Adachi

Scanning Electron Microscopy

Field emission occurs at the sharp apex of a metal needle, so that it can be considered as providing a point electron source, which is a desirable feature for a fine focused electron beam. The disadvantage is its low stability. It is shown that the current fluctuations occur mainly due to the interaction with the residual gas in the vacuum; thus reduction of the interaction with the residual gas is essential for a stable field electron source. The stringency of the vacuum requirement has prevented wide application of the field emission electron source. New materials which have low work functions …

Application Of Chelex Standard Beads In Integrated Morphometrical And X-Ray Microanalysis, W. C. De Bruijn, M. I. Cleton-Soeteman

Scanning Electron Microscopy

Chelex ion exchange beads loaded with a known amount (18.3% weight percentage (w/w)) of platinum, have been co-embedded with a mouse peritoneal cell population. To establish the influence of the various deconvolution methods applied, upon the platinum concentration in cytoplasmic granules and erythrocytes these cross-sectioned beads are used as a standard. It is concluded that irrespective of the deconvolution method chosen 1) the Pt concentration inside the particles is identical when the particles and the co-embedded Chelex Pt standard, are analysed strictly under the same instrumental conditions 2) the Pt concentration outside the particle is zero, or virtually zero when …

Development Of Fungal Calcium Oxalate Crystals Associated With The Basidiocarps Of Geastrum Minus (Lycoperdales), H. T. Horner, L. H. Tiffany, A. M. Cody, G. Knaphus

Scanning Electron Microscopy

Calcium oxalate crystals were observed on facing peridial surfaces of developing basidiocarps of Geastrum minus. Five crystal forms were characterized by their outward shapes and X-ray diffraction patterns: Form One, small bipyramids (COD); Form Two, crystals with split tips (COD); Form Three, crystals with oriented overgrowths (COD); Form Four, large bipyramids (COD); and Form Five, rosettes of plate-like crystals (COM). Forms One and Two were first to appear after peridia separated in unopened basidiocarps, whereas Forms Three, Four and Five were present on exposed peridia of opened basidiocarps. Based on time of appearance …

Scanning Electron Microscopy As An Analytical Tool For The Study Of Calcified Intrauterine Contraceptive Devices, S. R. Khan, E. J. Wilkinson

Scanning Electron Microscopy

Within the endometrial cavity intrauterine contraceptive devices (IUDs) become encrusted with cellular, acellular, and fibrillar substances. Scanning electron microscopy was used to study the crust. Cellular material consisted mainly of blood cells and various types of bacteria. The fibrillar material appeared to be fibrin which was omnipresent in the crust and formed a thin layer immediately over the IUD surface. X-ray microanalysis of the acellular component of the crust revealed the presence of calcium. No other major peaks were identified. Near the IUD surface characteristic calcium phosphate crystals were present. Their microanalysis showed peaks for calcium and phosphorus. X-ray diffraction …

The Pleurograms And Seed Surface Patterns Of Some Mimosoideae (Leguminosae) Genera, Randy T. Baker, Terry L. Bridges, Louis H. Bragg

Scanning Electron Microscopy

Seeds of twenty species representing eight mimosoid genera were examined with scanning electron microscopy (SEM) to determine if variations in the pleurograms and seed topographies exist and if these variations might have taxonomic potential. The pleurogram has been previously considered a feature of many mimosoid seeds but has not been adequately described and critically evaluated as to its shape and other features. The pleurogram shapes of the examined seeds can be placed in four general categories: elliptic, ovate, obovate, lanceolate. If the length/width ratio of the pleurogram is considered as well as the extent of the openness of the pleurogram …

Recent Advances In X-Ray Microanalysis In Dermatology, Bo Forslind, Thomas G. Grundin, Magnus Lindberg, Godfried M. Roomans, Ylva Werner

Scanning Electron Microscopy

Electron microprobe and proton microprobe X-ray analysis can be used in several areas of dermatological research. With a proton probe, the distribution of trace elements in human hair can be determined. In contrast to sulfur, which is homogeneously distributed, calcium, iron, and zinc appear to be non-homogeneously distributed over the hair cross-section.

Electron microprobe analysis on freeze-dried cryosections of guinea-pig and human epidermis shows a marked gradient of Na, P and K over the stratum granulosum. In sections of freeze-substituted human skin this gradient is less steep. This difference is likely to be due to a decrease in water content …

Post-Mortem Storage Of Tissue For X-Ray Microanalysis In Pathology, Godfried M. Roomans, Joanna Wroblewski

Scanning Electron Microscopy

Possible alternatives to rapid freezing in liquid nitrogen of tissue for X- ray microanalysis of electrolytes at the cellular level were investigated. These alternatives might be used in cases where tissue becomes available for examination, e.g., at autopsy, but liquid nitrogen is not immediately available. Rat submandibular gland was used as a test tissue. Freezing of pieces of tissue in a conventional freezer at -80°C or even at -20°C retained the elemental distribution at the cellular level, and also retained the difference between a 'normal' and a 'pathological' (mimicked by an inject ion of a high dose of isoproterenol) situation. …

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 …

The Ballistic Phonon Signal In Low Temperature Scanning Electron Microscopy, R. P. Huebener, W. Metzger

Scanning Electron Microscopy

By scanning the surface of a specimen cooled to liquid-helium temperature with the electron beam, ballistic phonons are generated which can be used for acoustic imaging. The anisotropy of the ballistic phonon propagation caused by the phonon focusing effect has been observed in recent experiments. The simultaneous operation of two or more small-area phonon detectors during the scanning process appears promising for three-dimensional acoustic imaging of structural inhomogeneities even far from the specimen surface. The principles of this scheme for acoustic imaging are discussed and the spatial resolution limits are estimated.

Towards The Ultimate Scanning Electron Microscope, Albert V. Crewe

Scanning Electron Microscopy

An analysis of all the factors which contribute to the electron probe size in a scanning electron microscope and of the correct method of combining those effects to give optimum performance. Assuming perfect specimen preparation the only other factors are the non-local nature of the basic electron interactions and the nature of the display system.

Analysis Of Backscattered Electron Signals For X-Ray Mask Inspection, Michael G. Rosenfield

Scanning Electron Microscopy

A rapid and automated inspection system is a necessity for the detection of defects in x-ray and optical lithography masks. The design of an electron-beam mask inspection system requires a complete understanding of the backscattered electron signal from the various defects which will be encountered. A Monte Carlo simulation program has been used to study the effects of electron-beam size, detector placement, defect type, electron-beam voltage, and absorber thickness on the back-scattered electron signal.

Early Development Of The Vertebrate Limb: An Introduction To Morphogenetic Tissue Interactions Using Scanning Electron Microscopy, Robert O. Kelley

Scanning Electron Microscopy

The developing limbs of most vertebrates serve as a model system for studies of morphogenesis, pattern formation, cell and tissue interactions and cell differentiation. Mesoderm in the flank of the embryo induces overlying ectoderm to form a thickened, stratified or pseudo-stratified epithelium which becomes the highly specialized apical ectodermal ridge. In turn, the apical ridge specifies individual limb parts (first from structures proximal to the body axis, then to more distal components) and is required for those elements to form. If the ridge is removed, subsequent limb development ceases and no further limb parts appear. The series of ectodermal-mesodermal interactions …

Progress In High Resolution Scanning Ion Microscopy And Secondary Ion Mass Spectrometry Imaging Microanalysis, R. Levi-Setti, G. Crow, Y. L. Wang

Scanning Electron Microscopy

The performance of a new high resolution scanning ion microprobe (SIM) is elucidated with regard to imaging capabilities using the ion-induced secondary electron (ISE) or secondary ion (ISI) signals, and the mass-resolved signal from a secondary ion mass spectrometry (SIMS) system. The new instrument focuses a beam extracted from a liquid metal ion source (LMIS) to a range of spot sizes reaching the 20 nm level. The probe current (1.6 pA) available at this level of lateral resolution, which approaches the theoretical resolution limits of the SIMS method, is still adequate to obtain detailed isotopic maps for surfaces rich in …

A Scanning Electron Microscopic Technique For Three-Dimensional Visualization Of The Spatial Arrangement Of Metaphase, Anaphase And Telophase Chromatids, David A. Welter, Lon D. Hodge

Scanning Electron Microscopy

Chromosome and chromatid alignment in mitotic configurations remains a topic of interest because there is little precise information. For example, reconstruction of mitotic configurations from serial sections collected with transmission electron microscopy has proven to be neither practical nor a sensitive method for conceptualizing these arrangements. Similarly light microscopy has been even more unsatisfactory because of its limited resolution and lack of three-dimensional capabilities. These limitations conceivably could be overcome by visualization of mitotic configurations by scanning electron microscopy (SEM). However, SEM has its limitations, of which the most obvious with regard to visualization of mitotic configurations, is that such …

The Use Of The Scanning Electron Microscope In Studying The Heat Treatment Of Prehistoric Lithic Artifacts From The North Florida Weeden Island Period Mckeithen Site, G. Michael Johnson

Scanning Electron Microscopy

In this paper, I discuss a study in which I attempted to determine whether or not the inhabitants of the McKeithen site, a Weeden Island Period mound and village complex in what is today northern Florida, employed heat treatment as part of their lithic reduction technology, and if so, at what point in the reduction sequence it was conducted. I used a scanning electron microscope (SEM) to photograph raw and heat treated control samples of northern Florida chert, then debitage and tools of chert and silicified coral from the McKeithen site which represented the range of colors and luster present …

Analysis Of Minerals Using Specimen Isolated Secondary Ion Mass Spectrometry, J. B. Metson, G. M. Bancroft, H. W. Nesbitt

Scanning Electron Microscopy

Considerably improved suppression of molecular ions in secondary ion mass spectrometry (SIMS) spectra of nonconductor minerals has been obtained using a CAMECA IMS-3f ion microscope with unconventional operating conditions [so-called specimen isolated (SI) conditions]. In a zircon spectrum close to forty elements are positively identified and molecular ions such as oxides and hydrides have very low intensities. Thus, with a ²⁸Si⁺ intensity of 10⁶ cps, the Si⁺/Si0⁺ ratio is 10⁵, and the ³⁰SiH⁺ intensity is low enough to enable quantitative analysis using ³¹P⁺ down to 0.01 wt % …

Microprobe Analysis In Human Pathology, D. Baker, K. G. Kupke, P. Ingram, V. L. Roggli, J. D. Shelburne

Scanning Electron Microscopy

This tutorial paper reviews the literature on the application of microprobe analysis to practical problems in diagnostic human pathology. The goal is to allow the reader ready access to the literature on specific clinical problems. Specimen preparation and commonly encountered artifacts are also considered. It is concluded that energy dispersive x-ray microanalysis and backscattered electron imaging are at present the most generally useful microprobe techniques for clinical work, and are no longer solely research tools. The findings often have diagnostic, therapeutic, and/or legal implications.

Calcium Oxalate Urolithiasis In The Rat: Is It A Model For Human Stone Disease? A Review Of Recent Literature, S. R. Khan, R. L. Hackett

Scanning Electron Microscopy

Calcium oxalate stone disease is the most common human urinary stone disease in the Western Hemisphere. To understand different aspects of the disease, calcium oxalate urolithiasis in the rat is used as a model. Spontaneous calcium oxalate urolithiasis is very rare in rats. Thus the disease is experimentally induced and the rats are generally made hyperoxaluric either by administration of excess oxalate, exposure to the toxin ethylene glycol, or various nutritional manipulations. All the experimental models show renal injury associated with crystal deposition. Calcium oxalate crystals are in most cases intraluminal in renal tubules and often attached to the basal …

Electrical Surface Breakdown: Secondary Electron Emission And Electron Spectroscopy Of Insulators, J. P. Vigouroux, C. Le Gressus, J. P. Duraud

Scanning Electron Microscopy

These results question the usual scheme of flashover. They lead to a different interpretation based on classical concepts in solid state physics which can be verified at every step. An ionizing cascade in the bands, rather than a cascade of electron multiplication on the insulating surface, could explain the flashover, the conditioning and the deconditioning of high voltage generators through the building of a surface charge. As in the usual model the positive charge is responsible for the flashover, in this new model the building of this charge is the basis of the conditioning. The ionizing cascade in the bands …