bluuebunny/crossref_metadata_2025_split huggingface dataset:
The process of amorphization induced by electron irradiation in alloys
Authors: Fujita Hiroshi 
Published: February 2005

AbstractAmorphization induced by electron irradiation in Ni–50 at% Ti crystals has been investigated by electron microscopy. In order to clarify successive stages of amorphization, micrographs were taken in vairous regions where the total dose of electrons was continuously changed. Contrast was manipulated by changing the reflecting condition. Results obtained are summarized as follows: (a) Amorphization occurs inhomogenously; (b) there is a critical size, i.e., about 5 nmø in the crystals, for observing sharp lattice images in small blocks; (c) lattice images change to short and wavy fringe contrasts when the block size becomes smaller than the critical one, and finally they disappear; and (d) boundary contrast of the blocks rapidly decreases with decreasing size, and is hardly observed when the size becomes smaller than the critical one. Based on the results, the cause of abnormal fringe contrasts in fine blocks, the amorphization process, and atomic structures of amorphous materials are discussed.
Merits of high resolution electron microscopy in the study of alloy structures
Authors: Kuo K. H. , Ye H. Q. , Li D. X. 
Published: February 2005

AbstractWe found that high resolution electron microscopy has the following merits in the study of alloy structures: (1) New phases too small to be studied by x‐rays, such as σ‐related phases, may be studied; (2) local and highly disordered structures, such as domain boundaries and domains of only a few unit cells, are more easily studied; and (3) it is easier to order solute atoms, such as Ti atoms columns in Cu4Ti.
Automatic measurement of scanning beam diameter using an on‐line digital computer
Authors: Oho Eisaku , Kobayashi Masaaki , Sasaki Toshihide , Adachi Koichi , Kanaya Koichi 
Published: February 2005

AbstractA method for the measurement of electron probe beam diameter by digital image processing has recently been published. The purpose of the present report is to describe the development of an automatic system for beam diameter measurement. To complete this system, a method based on a theory which combines automation and high‐resolution conditions is proposed. In practice, the beam diameter is measured from the STEM image of a crystalline hole in a gold thin film, utilizing an on‐line computer system equipped with newly developed digital processing programs linked to a SEM in the transmission mode. The functions of the programs include statistical processing, matching, noise removal, interpolation, selection, and rotation. By combining these functions, the scanning beam diameter is accurately measured, in spite of difficulties, under most electron microscope operating conditions. The user simply appoints the edge included in the STEM image.
A comparison of unidirectional and rotary metal evaporation shadowing by computer simulation
Authors: Colquhoun William , Sokol Roger 
Published: February 2005

AbstractThis work employs a Fortran program to simulate rotary shadowing, that is, metal evaporation deposits in which the substrate is rotating during the deposition process. The results are compared with computer simulations of unidirectional shadowing published in a previous paper. (See Colquhoun et al., 1985). The analysis shows that a substantial improvement in resolution is possible with rotary shadowing. The improved information retrieval amounts to ∼15% with a shadow angle of 33° and ∼37% with a shadow angle of 8°. Unidirectional shadowing results in a grain linearity; the computer simulations show that this undesirable effect is eliminated by the rotary process.These advantages of rotary shadowing are discussed along with the more straight forward interpretability of the rotary shadowed images. These advantages are weighed against the higher contrast generated by the unidirectional shadowing process.
Advances in ultrarapid freezing for the preservation of cellular ultrastructure
Authors: Gilkey John C. , Staehelin L. Andrew 
Published: February 2005

AbstractMost of our current knowledge of cellular ultrastructure is derived from studies of chemically fixed and chemically cryoprotected preparations. In the first part of this review, we document the many artifacts associated with chemical techniques that render them unsuitable for further refinement of our understanding of cellular ultrastructure. The best method currently available for the preservation of cellular ultrastructure is ultrarapid freezing. The second part of this review is a consideration of the physics of ice crystal formation in biological systems, which suggests that ice crystals will be present in any frozen, uncryoprotected specimen. We define an ultrarapidly frozen preparation as one in which the ice crystals are so small as to be invisible at the electron microscopic level. Improvements in the ease of application and reliability of ultrarapid freezing techniques have reached the point that these techniques can be used by anyone requiring the best achievable preservation of cellular ultrastructure. In the third part of this review, we describe and critique the five methods of ultrarapid freezing in current use.
A method for sectioning and handling frozen sections for scanning electron microscopy
Authors: Mowry Thomas M. , Whalon Mark E. , Klomparens Karen 
Published: February 2005

AbstractGlutaraldehyde‐fixed insects were embedded in Tissue‐TekR and sectioned on a liquid‐nitrogen‐cooled stage. The sections were sandwiched between two layers of microscope lens paper and all postsectioning treatments were carried out on this sandwich, including dehydration and critical‐point drying. In some cases, the sections were placed on filter membranes and lyophilized. These procedures produced intact specimens which maintained internal morphology as well as inter‐ and intracellular integrity without expensive or specialized equipment.
Surfactants as resin modifiers and their effect on sectioning
Authors: Mollenhauer Hilton H. 
Published: February 2005

AbstractEase of cutting thin sections with glass knives is markedly improved if the embedding resin contains a surfactant such as lecithin. With lecithin, it is possible to cut 50–100 thin sections from the same place on the knife edge even after facing off the block with 1–2‐μm‐thick sections. Image quality is similar to that of the unmodified resin if the resin formula is optimized. If not, some chatter or a “mottled” appearance of the tissue image may be present. Lecithin does not significantly affect sectioning with a diamond knife or the appearance of the section in the microscope. The increased ease of sectioning with glass presumably will be translated to diamond knives in the form of an increased useful life of the cutting edge.
Ultra‐high voltage electron microscopy: Past, present, and future
Authors: Fujita Hiroshi 
Published: February 2005

AbstractHigh voltage electron microscopy has shown numerous advantages for the study of natural science, including biology, but it is especially useful in materials science. The most important advantage for materials science is in‐situ experiments on detailed processes of the same phenomena that occur in bulk materials. For such in‐situ experiments, the specimens should be thicker than a few microns to observe the behavior of lattice effect. The maximum observable thickness of the specimens and other advantages markedly increase with increasing accelerating voltage, and since 1965, two 3 MV instruments have been installed. The present paper is mainly concerned with these 3 MV electron microscopes and their applications to new research fields.
Rotary shadowing with platinum‐carbon in biological electron microscopy: A review of methods and applications
Authors: Chandler Douglas E. 
Published: February 2005

AbstractRotary shadowing when combined with such specimen preparation techniques as quick freezing and deep etching, critical point drying, and glycerol spraying is a highly versatile method of visualizing cell and macromolecular ultrastructure. This review outlines the procedures commonly used to prepare specimens for rotary shadowing and evaluates the relative merits of rotary shadowing when compared to unidirectional shadowing and negative staining.
Modification of a TEM‐goniometer specimen holder to enable beam current measurements in a (S)TEM for use in quantitative X‐ray microanalysis
Authors: Stols A. L. H. , Smits H. T. J. , Stadhouders A. M. 
Published: February 2005

AbstractIn order to have available a specimen holder suited to measure the beam current as is often required in quantitative electron probe X‐ray microanalysis, the rod of a low background beryllium specimen holder of a transmission electron microscope was modified. The tip was electrically insulated from the mass of the microscope and connected electrically to the central contact of a BNC connector mounted on the specimen holder handle. With this modified specimen holder the current absorbed by the specimen and/or the specimen holder could be measured easily and accurately. The modified specimen holder has been used to measure the beam current stability of an analytical electron microscope under various conditions. Data were obtained for tungsten as well as lanthanum hexaboride cathodes. Small changes to other types of specimen tips made it possible to exchange these for the low background tip.
Three‐dimensional reconstruction from serial section images by computer graphics
Authors: Baba Norio , Nakamura Shin‐Ichi , Kino Isamu , Kanaya Koichi 
Published: February 2005

AbstractA method is described that allows a three‐dimensional object to be reconstructed from micrographs of serial sections by means of computer graphics. The reconstructed object, which can be rotated three‐dimensionally, is displayed on a colour visual display unit, and the object is shaded in order to provide an illusion of a three‐dimensional structure. Moreover, the technique makes it possible to observe an inner structure as seen through an outer one.
Characterization of chemically defined neurons and their cellular relationships by combined immunocytochemistry and radioautographic localization of transmitter uptake sites
Authors: Bosler Olivier , Beaudet Alain , Pickel Virginia M. 
Published: February 2005

AbstractRadioautography and immunocytochemistry may be combined at the light and electron microscopic levels for simultaneously localizing uptake sites for exogenous transmitter molecules [such as (3H)monoamines or (3H)amino acids] and endogenous transmitter‐related antigens (classical transmitters and their synthesizing enzymes as well as neuropeptides) in the central nervous system. Silver grain accumulations indicative of transmitter uptake sites are readily distinguishable from immunocytochemical labels of the peroxidase‐antiperoxidase (PAP), avitin‐biotin, or colloidal gold methods. The combination of uptake radioautography and immunocytochemistry may be applied to the investigation of (1) the chemical identity of (3H) transmitter‐accumulating elements, (2) the coexistence of different neurotransmitters within the same neurons, and (3) the cellular basis of interactions between certain neurotransmitters, in particular monoamines, GABA, and neuropeptides. This article describes and evaluates the method and reviews the available experimental data derived from its application.
The use of scanning electron microscope autoradiography to localize the blueberry shoestring virus in its aphid vector
Authors: Klomparens Karen L. , Petersen Maureen A. , Ramsdell Donald C. , Chaney William G. 
Published: February 2005

AbstractScanning electron microscopy autoradiography (SEM‐AR) in conjunction with light microscope autoradiography (LM‐AR) was used to follow the movement of 125I‐labeled blueberry shoestring virus (BBSSV) through its aphid vector Illinoia pepperi with varying acquisition access periods (AAP). At 6 hr AAP, the virus had reached the stomach; at 12 hr AAP, it had reached the anterior of the intestines, and after 48 hr, AAP was present throughout the aphid. SEM‐AR using backscatter electron detection proved very useful because the sample bulk resulted in a shortened exposure time compared to LM sections, correlation of the autoradiograms could be made with fine structure, preparing large numbers of samples was easy, and examining whole longitudinal sections of aphids at low magnification with a clearly visible marker was possible. Limitations were mostly attributed to sample preparation and, in some cases, were easily remedied.
Freeze‐Fracture of physiologically identified neuromuscular junctions from single frog muscle fibers
Authors: Ko Chien‐Ping , Propst Jon W. 
Published: February 2005

AbstractWe developed a technique for freeze‐fracturing single physiologically identified neuromuscular junctions. This technique permits direct comparison of quantal content with morphological variables such as active zone length per unit terminal length for the same cell. The technique was developed to elucidate the structural basis for variability in transmitter release at the neuromuscular junction. The procedures were as follows: (1) record quantal content by conventional intracellular recordings; (2) mark cells for identification by fluorescent dye injection; (3) fix and stain endplate cholinesterase; (4) glycerinate and remove single fibers from the muscle; (5) draw endplate morphology; (6) freeze‐fracture single muscle fibers; (7) examine in a transmission electron microscope; and (8) photograph and measure nerve terminal membrane ultrastructure. We found that approximately 15% of freeze‐fractured single muscle fibers exhibited nerve terminal active zones. To demonstrate the usefulness of this technique, physiological and morphological information from an identified junction is presented. Freeze‐fracture of identified cells has several advantages over thin sections, which cannot accurately show such things as active zone length, spacing, or intramembrane particles. This technique also has applications to the study of active zone ultrastructure in situations where neurotransmitter release is known to differ from normal levels. In addition, direct correlations between membrane structure and function can be studied in other preparations by this method.
A modified goodman's technique for obtaining rocking‐beam type patterns
Authors: Kang Zhenchuan 
Published: February 2005

AbstractA new method was developed for convergent beam electron diffraction (CBED) and large angle convergent beam electron diffraction (LACBED) in the JEM‐100CXII. This method is obtained in the imaging mode using the defocus objective lens and by re‐setting condenser‐2. A multi‐dark field CBED pattern was achieved in two ways.
Fracture—Permeation: A technique to assess cytoplasm compactness after glutaraldehyde‐fixation
Authors: Barbosa Maria Luiza F. , da Silva Pedro Pinto 
Published: February 2005

AbstractWe have developed a method—“fracture‐permeation”—to assess the compactness of the cytoplasm in glutaraldehyde‐fixed cells. Cells or tissues are fixed in glutaraldehyde, impregnated with glycerol, and frozen in liquid nitrogen. The cells are freeze‐fractured, thawed, deglycerinated, and immersed in concentrated solutions of globular proteins. In initial experiments, we used native ferritin (NF) to permeate model matrices made of bovine serum albumin (BSA). We show that permeation depends on the concentraion of proteins within the cross‐linked matrix: NF permeates matrices made from 10 or 15% (w/v) BSA solutions but do not permeate matrices made from solutions with 20% (w/v) protein or more. With freeze‐fractured cells, ferritin molecules were unable to permeate the cross‐linked cytoplasm of fungal zoospores and cysts, used here as examples of resting cells. In human lymphocytes from peripheral blood, permeation of ferritin was limited or absent, but it became massive in cells activated by phytohemagglutinin. Massive permeation of ferritin was also observed within the cytoplasmic matrix of other active cells (fungal sporangia, germinating cysts). In the examined resting cells, glutaraldehyde crosslinks the proteins into a dense matrix that effectively excludes ferritin (diameter 12 nm). These findings cannot be explained by models that envisage all cytoplasmic proteins congregated into a single‐phase microtrabecular lattice with the nature and dimensions proposed by Porter and co‐workers. We conclude that compactness of the cytoplasm matrix depends on the physiological state of the cell: It varies through differentiation and is related to the degree of cellular activity.
Postembedment staining of complex carbohydrates: Influence of fixation and embedding procedures
Authors: Thomopoulos G. N. , Schulte B. A. , Spicer S. S. 
Published: February 2005

AbstractIn recent years technological advancements have led to improvements in ultrastructural cytochemical methods for localizing and characterizing complex carbohydrates. In particular the introduction of lectins with specific affinities for various sugars and sugar sequences as histochemical probes has increased knowledge concerning the cellular and subcellular distribution of glycoconjugates. Development of nonepoxy‐based embedding materials has provided increased sensitivity compared to the earlier less specific methods and the current lectin methods for localizing sugar moieties. Postembedment staining based on the reactivity of functional groups present in sugars, such as hydroxyl groups, vicinal diol groups, carboxyl groups, and sulfate esters, requires specific conditions for tissue fixation and embedding. The same requirements pertain to staining based on lectin binding. The influence of fixation and embedment using older and newly developed embedding mixtures on the ultrastructural demonstration of complex carbohydrates is considered in this discussion. Fixation with osmium tetroxide and embedment in epoxy resins provides the least sensitive combination for the detection of the reactive groups of complex carbohydrates. The best ultrastructural demonstration of glycoconjugates is achieved when nonosmicated tissues are embedded in nonepoxy resins.
An inexpensive and highly efficient device for observing a transmitted electron image in SEM
Authors: Oho Eisaku , Sasaki Toshihide , Adachi Koichi , Muranaka Yoshinori , Kanaya Koichi 
Published: February 2005

AbstractAn inexpensive, efficient device that supplies a transmission mode to the conventional SEM has been developed. The transmitted electrons strike a metal plate, and these generate secondary electrons that are proportional to the quantity of the transmitted electrons. The generated electrons are collected by the secondary electron detector. Hence, the performance of this device is influenced by the number of secondary electrons generated in the metal plate. In order to construct a device that can attain the best transmitted electron image, the signal‐to‐noise ratio of images, obtained from various trial devices, were measured by a newly‐developed digital image processing program. When the material and shape of the device are selected, to produce high‐secondary emission, the efficiency of the device compares with that of a relatively expensive standard detector system (scintillator detector).
Calibration of focusing steps and image rotation of electron microscopes
Authors: Hsu Tung 
Published: February 2005

AbstractReflection electron microscopy (REM) is used to calibrate the focusing steps and rotation of electron microscopes. The calibration of focusing steps is done by the direct measurement of the shift on in‐focus positions in the REM micrographs. Rotations between the diffraction patterns and images are calibrated in the usual way. By using the REM geometry, the reflection high energy electron diffraction (RHEED) patterns and REM images have no rotation symmetry, thus eliminating the 180° uncertainty.
Removal of epoxy‐attached thin sections from glass slides by plasma etching
Authors: van Deusen Stuart B. , Mackinnon Ian D. R. 
Published: February 2005

AbstractThin‐sectioned samples mounted on glass slides with common petrographic epoxies cannot be easily removed (for subsequent ion‐milling) by standard methods such as heating or dissolution in solvents. A method for the removal of such samples using a radio frequency (RF) generated oxygen plasma has been investigated for a number of typical petrographic and ceramic thin sections. Sample integrity and thickness were critical factors that determined the etching rate of adhesive and the survivability of the sample. Several tests were performed on a variety of materials in order to estimate possible heating or oxidation damage from the plasma. Temperatures in the plasma chamber remained below 138°C and weight changes in mineral powders etched for 76 hr were less than ±4%. A crystal of optical grade calcite showed no apparent surface damage after 48 hr of etching. Any damage from the oxygen plasma is apparently confined to the surface of the sample, and is removed during the ion‐milling stage of transmission electron microscopy (TEM) sample preparation.
Real‐space reconstructions of nonideal helical particles
Authors: Bluemke David A. , Carragher Bridget , Potel Michael J. , Josephs Robert 
Published: February 2005

AbstractWe have studied the manner in which real‐space reconstructions of helical particles are affected by particle distortions commonly present in electron micrographs. The effects of image distortions due to noise, nonuniform negative staining, pitch variations, particle tilt, and flattening on the reconstructed cross‐section are difficult to visualize, and therefore we have developed a test system using model images in order to facilitate our investigations. In addition, we have examined the effect of incorrect estimates of the particle repeat length and location of the helical axis on the reconstructed density map. By using models that incorporate defined image distortions, we are able to compare directly reconstructions of the models with those of the idealized structure. This approach can help indicate sources of specimen distortion limiting the resolution of particle reconstructions.
High temperature controlled atmosphere experiments for catalysts in a transmission electron microscope
Authors: Chan Ignatius Y. 
Published: February 2005

AbstractA new transmission electron microscopy (TEM) specimen preparation procedure for high temperature experiments using a controlled atmosphere specimen holder (HTCASH) has been developed. It is designed for studying the microstructure of catalyst specimens before and after treatments in various gases. The procedure involved (1) finding a new formula for the embedding material, (2) devising a new method of making specimen supports, and (3) developing a method for removing the embedding material after the specimen has been microtomed. These techniques were then brought together to produce the ideal specimens for the HTCASH experiments. As an extra benefit, this procedure is also suitable for preparing specimens for ultrahigh resolution imaging experiments. The application of the new procedure in HTCASH experiments is illustrated through a high temperature reduction of a Co/SiO2‐923 catalyst.
Cyclic X‐Y mechanical tests: A new method to perform in situ reversed‐deformation experiments in the high‐voltage electron microscope
Authors: Kassner Michael E. , Sleeswyk Andre W. , Echer Charles J. 
Published: February 2005

AbstractThere has been, in the past, only limited success with in situ cyclic or reversed plastic deformation tests in the transmission electron microscope (TEM). This is probably partly due to problems associated with buckling of the foil when an applied tensile or shear stress is reversed. Mechanical analysis shows that dislocation movement can be reversed by tensile stressing in alternating perpendicular directions (i.e., 90° rotations of a tensile stress); thus buckling of the foil can be avoided. A design for performing such X‐Y in situ TEM tests is presented, with observations that demonstrate its feasibility.