bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analytical electron microscopy study of high Tc superconductor YBa2Cu3O7
Authors: Sabatini R. L. , Heald S. M. , Suenaga Masaki , Moodenbaugh A. R. , Jones R. H. 
Published: February 2005

AbstractThe high Tc superconducting material YBa2Cu3O7 shows a complex relationship between microstructure and oxygen content, which are controlled by length of heat treatment, atmosphere, and quench rate. An AEM investigation studying changes in the oxygen near edge features was undertaken. Electron energy loss spectroscopy (EELS) measurements have the important advantage that they can be made on single crystal grains, allowing orentation‐dependent studies. Both ion‐milled and crushed samples with varying O2 content were analyzed. The structure of YBaCu3O7 was determined by neutron diffraction to be orthorhombic with distinct Cu‐O chains along the b‐axis as well as Cu‐O planes in the a—b plane. Therefore, by looking for a crystallographic dependence of the oxygen K‐edge one might be able to distinguish inequivalent oxygen atoms by their core level binding energy and correlate site occupancy with varying O2 content. The EELS results on the oxygen K‐edge are strongly dependent on oxygen content, most noticeably when the c‐axis is parallel to the electron beam.
Electron microscopy study of twin behavior in GdBa2Cu3Ox and YBa2Cu3Ox
Authors: Mitchell T. E. , Roy T. , Schwarz R. B. , Smith J. F. , Wohlleben D. 
Published: February 2005

AbstractTwins are ubiquitous in the perovskite superconductors. They form during cooling from high temperatures through the tetragonal‐to‐orthorhombic phase transformation. Their behavior has been studied by transmission electron microscopy using a liquid‐nitrogen‐cooled specimen holder. It is observed that extra twins sometimes form in coarse‐twinned regions to give a “refined” twin structure; this is thought to be induced by thermal stresses from the electron beam. Prolonged electron irradiation (with little beam heating) results in transformation to tetragonal with a loss of the twin structure; this is probably due to disordering of the oxygen sublattice by knock‐on displacement. The same transformations can be induced by deliberate electron beam heating. In both cases the twinned orthorhombic structure can be restored by re‐ordering of the oxygen ions, in the first case by removing the beam and in the second case by allowing the specimen to cool.
Digitization of electron micrographs: A comparison of three different types of scanners
Authors: Olofsson Anders , Kavéus Urban , Hebert Hans 
Published: February 2005

AbstractSome aspects of digitization of electron micrographs have been investigated. The performances of a flat‐bed, a rotating drum, and a diode array scanner have been evaluated. Estimates have been achieved for resolution, mechanical and optical stability, and optical density response. It is concluded that for routine transmission electron microscopy of, for example, negatively stained biologic specimens, a diode array scanner produces data good enough to obtain resolutions at a level normally expected. High speed is the major advantage with this type of equipment. However, for high‐resolution work it is necessary to use a conventional scanner with a relatively slow scan speed.
Ultrathin cryosections in the plane of cell monolayers: Evaluation of their potential for antibody localization studies of the cytoskeleton
Authors: Langanger Gabriele , De Mey Jan 
Published: February 2005

AbstractIn spite of the fact that the preembedding method is satisfactory for the ultrastructural localization of cytoskeletal proteins, there is a need for a localization method that retains the cells' ground substance, delicate filament arrangements, and membrane‐filament interactions and provides a good delineation of ultrastructural detail. Ultracryomicrotomy, a resinless sectioning method, can combine good morphology with optimal antibody labeling. Until now, however, it has not been possible to section cell monolayers parallel to their plane of growth. This is a prerequisite for the localization of proteins along segments of filaments, contained within the section thickness. We describe such a method and give a first appreciation of its potential for antibody localization studies of cytoskeletal proteins. The method consists of seeding cells on a parallel 0.75‐mm‐thick gelatin substrate that can later be cut and used as a mounting block. An adapted negative staining has yielded a very useful delineation of the well‐preserved structures within the cells, even in combination with immunogold labeling. The latter has been in its indirect version less satisfactory in dense microfilament bundles because of penetration problems, and more satisfactory on microtubules. Clearly, the penetration properties of gold probes will have to be improved before this method will become widely applicable. The availability of a sectioning method like this will provide the basis for further progress. There will be many cases which will justify the use of this relatively more difficult approach.
Quantitative X‐ray microanalysis of biological specimens
Authors: Roomans Godfried M. 
Published: February 2005

AbstractQualitative X‐ray microanalysis of biological specimens requires an approach that is somewhat different from that used in the materials sciences. The first step is deconvolution and background subtraction on the obtained spectrum. The further treatment depends on the type of specimen: thin, thick, or semithick. For thin sections, the continuum method of quantitation is most often used, but it should be combined with an accurate correction for extraneous background. However, alternative methods to determine local mass should also be considered. In the analysis of biological bulk specimens, the ZAF‐correction method appears to be less useful, primarily because of the uneven surface of biological specimens. The peak‐to‐local background model may be a more adequate method for thick specimens that are not mounted on a thick substrate. Quantitative X‐ray microanalysis of biological specimens generally requires the use of standards that preferably should resemble the specimen in chemical and physical properties. Special problems in biological microanalysis include low count rates, specimen instability and mass loss, extraneous contributions to the spectrum, and preparative artifacts affecting quantitation. A relatively recent development in X‐ray microanalysis of biological specimens is the quantitative determination of local water content.
Quantitative X‐ray analysis of biological fluids: The microdroplet technique
Authors: Roinel Nicole 
Published: February 2005

AbstractX‐ray microanalysis can be used to quantitatively determine the elemental composition of microvolumes of biological fluids. This article describes the various steps in preparation of microdroplets for analysis: The manufacturing of micropipettes, the preparation of the specimen support, the deposition of droplets on the support, shock‐freezing, and lyophilization. Examples of common artifacts (incomplete rehydration prior to freezing or partial rehydration after lyophilization) are demonstrated. Analysis can be carried out either by wavelength‐dispersive analysis, which is the most sensitive method, or by energy‐dispersive analysis, which is more commonly available. The mininum detectable concentration is 0.05 mmol · liter−1 for 0.1‐nl samples analyzed by wavelength‐dispersive spectrometry and 0.5–1 mmol · liter−1 for samples analyzed by energy‐dispersive spectrometry. A major problem, especially in wavelength‐dispersive analysis, where high beam currents are used, is radiation damage to the specimen; in particular chloride (but also other elements) can be lost. Quantitative analysis requires the use of standard solutions with elemental concentration in the same range as those present in the specimen.
Morphological alterations of the glomerular (visceral) epithelium in response to pathological and experimental situations
Authors: Andrews Peter 
Published: February 2005

AbstractThe glomerular (visceral) layer of Bowman's capsule is comprised of a unique population of cells which have been termed “podocytes.:” Arising from these cells are large major processes and numerous smaller foot processes which completely surround underlying glomerular capillary loops. Podocyte foot processes interdigitate with each other and are separated by spaces (filtration slits) which are designed to facilitate flow of a large amount of filtrate across the glomerular wall. Podocytes exhibit dramatic morphological changes in response to the nephrotic syndrome and some forms of acute renal failure and may play an important role in the pathophysiology of these conditions. In vitro and in vivo studies have shown that a reduction in the sialic acid component of a thick anionic surface coat plays a major role in the morphological changes that these cells exhibit in the nephrotic syndrome. Also, it has been shown that filamentous actin concentrated mainly within podocyte foot processes are the contractile elements responsible for altering the shapes of these processes. There is evidence to suggest that by altering the shapes of their foot processes, podocytes in the normal kidney are able to alter the number of fully patent filtration slits and thereby actively regulate the rate of solute efflux across the glomerular wall. In vitro and in vivo studies have indicated that cytoplasmic microtubules are probably not involved in alterations of the podocyte foot processes but do appear important in maintaining the morphological integrity of podocyte cell bodies and their major processes. In the present paper, the morphological changes which glomerular podocytes exhibit in response to the nephrotic syndrome, various forms of acute renal failure, and during in vitro incubation are discussed along with studies of the possible roles of cytoplasmic microtubules, microtubules, and the glomerular anionic surface coat in these changes.
Identification of molecules in the kidney utilizing immunocytochemistry
Authors: Kashgarian Michael 
Published: February 2005

AbstractImmunocytochemistry of the kidney is a unique method to integrate physiology, biochemistry, and molecular biology with morphology. Both mono‐ and polyclonal antibody reagents are useful and each has advantages and disadvantages. Specificity with low background is of the greatest importance. Tissue preparation techniques depend on the antigen being studied as well as the methodology to be used. Pre‐ and postembedding techniques combined with visualization with peroxidase reaction products or with particulate markers such as ferritin and gold must be chosen for each individual circumstance to be studied. Important applications in the kidney have included studies of glomerular antigens, specific transport proteins, and segment‐specific antigens of unknown specificity. Future utilization of this technique with new molecular probes will greatly enhance our knowledge of the biology of the kidney.
Hypoxic injury to medullary thick ascending limbs in perfused rat kidneys: Reversible and irreversible phases
Authors: Brezis M. , Kopolovic J. , Rosen S. 
Published: February 2005

AbstractThe tubular epithelial cells located in the renal medulla are normally working in a hypoxic milieu. In isolated rat kidneys perfused with a cell‐free medium, the medullary thick ascending limbs of Henle's loop are selectively and reproducibly injured by the imbalance between oxygen demand and supply in this area. Hypoxic lesions rapidly progress from reversible to irreversible forms of cell damage. Reversible injury consists of chromatin margination and mitochondrial swelling, which can disappear upon restoration of an adequate balance of oxygenation. Irreversible injury consists of nuclear pyknosis and cytoplasmic fragmentation, lesions which persist after re‐oxygenation or even progress to cell death. Reversible and irreversible phases of hypoxic injury in this distal tubule segment are comparable to, but different from, those previously defined for the proximal tubule.
Image registration in electron microscopy: Application of a robust method
Authors: Bonnet Noël , Liehn Jean‐Claude 
Published: February 2005

AbstractThe geometric registration of two electron microscopic images generally is performed by maximizing the cross‐correlation coefficient between them. We show that a new similarity measure (the number of sign changes) is useful for performing simultaneously geometric and gray‐level registration. This method is robust, which means that it provides a good estimation of the parameters even in the presence of outliers that cannot be described by the registration model.
The use of specimen tilt in transmission electron microscopy of the central nervous system
Authors: Milroy Antonia M. , Ralston Diane D. 
Published: February 2005

AbstractThin sections of nervous tissue were viewed at different tilt angles using a transmission electron microscope equipped with a eucentric goniometer stage. In a comparison study of various degrees of tilt, one can observe additional morphological features within synaptic profiles, define subsynaptic structures such as Taxi‐bodies, and clearly see the crystalline formation of cytochemical tracers. This study demonstrates the value of tilting thin‐sections in the analysis of synapses and other biological material at the ultrastructural level.
Insulin and C‐peptide (proinsulin) packaging: A quantitative immunocytochemical approach
Authors: Hammel Ilan , Kalina Moshe 
Published: February 2005

AbstractC‐peptide and insulin antigenic sites in rat pancreatic β cells were both labeled by the protein A and immunogold techniques. Gold bead density in the secretory granules was correlated with granule size distribution. Our results demonstrate that the distribution patterns of antigenic sites for C‐peptide (which also represents proinsulin sites) and insulin are similar when granule size distribution is correlated to the density of antigenic sites. It was found that the ratio of C‐peptide to insulin in granules is independent of granule size. Examination of frequency histograms by a Kolmogorov‐Smirnov analysis excluded the possibility that the antigenic sites of C‐peptide and insulin are distributed in the same manner. Mean gold bead density for insulin antigen (97 ± 24) was slightly higher than C‐peptide density (64 ± 18). The efficiency of labeling was found to be very low; less than 0.1% of the theoretically estimated antigenic sites were labeled.
Improved chondrocyte morphology and glycogen retention in the secondary center of ossification following osmium‐potassium ferrocyanide fixation
Authors: Shepard Nora , Mitchell Nelson 
Published: February 2005

AbstractThe use of osmium‐potassium ferrocyanide as the secondary fixative greatly improved chondrocyte preservation and stabilized the cartilage matrix proteoglycan. The proteoglycan was similar in appearance to that seen following fixation in the presence of cationic dyes. Extensive glycogen preservation was noted in these cells, occupying the area prior to and during the formation of the secondary center of ossification. The volume and organization of the glycogen within the cell cytoplasm were greater than that following buffered osmium fixation, and the cellular vacuoles within were greatly reduced.The cells forming the secondary center prior to the onset of mineralization were of greatest interest, because other studies compared them with the primary growth plate and described them as showing signs of hypertrophy as early as 5 days postnatally, as is found in the primary growth plate. Our observations indicate that glycogen is present in these cells, and cellular enlargement was not present. The cells do not resemble the hypertrophic chondrocytes of the primary growth plate, as far as cytoplasmic content is concerned, and we suggest that they may contribute to the development of the secondary center in a different fashion.
Silver enhancement of gold probes (5–40 nm): Single and double labeling of antigenic sites on cell surfaces imaged with backscattered electrons
Authors: Namork Ellen , Heier Hans Erik 
Published: February 2005

AbstractSilver enhancement of immunogold‐labeled cells was carried out to increase the applicability of colloidal gold probes for visualization in the backscatter electron imaging (BEI) mode of a scanning electron microscope. Optimum conditions were established for single particle discrimination and differential counting of labeling density at low magnifications. Red blood cells double‐labeled with 15 + 40 nm and 5 + 20 nm gold probes were silver‐enhanced for 6 min and 20 min, respectively, at which times both pairs of labels increased to about 25 + 50 nm. The gold probes still appeared spherical after enhancement and were easily discriminated. Cells were also single‐labeled with the above probes and enhanced accordingly. The present method enables visualization of individual particles of any probe size, labeling one, or simultaneously two, antigenic sites on cell surfaces. The silver enhancement procedure thereby allows cells to be labeled with small probes with increased labeling efficiency.
Achievement of atomic resolution electron microscopy
Authors: Smith David J. 
Published: February 2005

AbstractAtomic‐level details are easily resolved in the latest generation of intermediate voltage electron microscopes, but structural information on the same scale can only be extracted under certain specific conditions. Some understanding of imaging theory, as well as an awareness of correct operating conditions, is required for reliable image interpretation. Several representative examples are chosen to illustrate the possibilities for atomic‐resolution imaging of materials, and perspectives and outlook for the technique are briefly discussed.
Fortran source listing for simulating three‐dimensional convergent beam patterns with absorption by the Bloch wave method
Authors: Zuo J. M. , Gjonnes K. , Spence J. C. H. 
Published: February 2005

AbstractThe FORTRAN source code is given for a computer program that calculates the two‐dimensional intensity distribution in convergent‐beam transmission electron microdiffraction (CBED) patterns from perfect crystals. The program uses the eigenvalue or Bloch‐ware method. It allows three‐dimensional dynamical diffraction, and so includes all higher‐order Laue zone effects without approximation. No symmetry reduction is included. The program accepts noncentrosymmetric or centrosymmetric crystal structures and allows absorption corrections to be included. It uses the “EISPACK” subroutines for the diagonalisation of a general complex matrix. Up to 100 CBED disks may be included. The code is also available via “Bitnet”.
Ultrastructural features of the AIDS virus (HIV) and its morphogenesis
Authors: Nakai Masuyo , Goto Toshiyuki , Imura Shunro 
Published: February 2005

AbstractHIV particles were usually seen on the surface of established lymphoid cells derived from AIDS patients or on CEM cells infected with HIV, and sometimes in cytoplasmic vacuoles. The virus particles were formed by a budding process from the plasma membrane of an infected cell. The budding particles were of a doughnut form. Various profiles of virus particles were seen extracellularly: type 1 had a bar‐shaped, electron‐dense core, type 2 had a central and type 3 an eccentric electron‐dense round core, type 4 was doughnut‐shaped, and type 5 had a layered core. However, projection patterns of the AIDS virus model suggested that type 1, 2 and 3 particles are similar. Therefore, the AIDS virus may be one of three main types: with or without a dense core, and with a layered core. It is thought that a particle with a layered core and a doughnut‐type particle may be immature viruses.
Fine architecture of the splenic terminal vascular bed as revealed by arterial and venous pressure‐loading perfusion fixation
Authors: Suzuki Teruo , Hataba Yoshiaki , Sasaki Hiroyuki 
Published: February 2005

AbstractThe three‐dimensional fine architecture of the red pulp of human and animal spleens, which as fixed by a modified version of the arterial and venous pressure‐loading perfusion fixation (AVPL perfusion fixation) method, is demonstrated by scanning and transmission electron microscopy. In the human spleen, changes in splenomegalias associated with hereditary spherocytosis and chronic portal hypertension are also introduced in addition to the normal architecture of the red pulp of spleens removed from patients with stomach cancer. The AVPL perfusion fixation of these spleens clearly visualized complicated three‐dimensional fine architecture of the red pulp and provided much important information on in situ morphology and dynamic change of the terminal vascular bed, including venous pressure‐dependent size change of the stomata and three‐dimensional shapes of the capillary terminal, with positive proof of their opening into the cordal reticular tissue. In studies of the spleen associated with portal hypertension, the AVPL perfusion fixation is considered a necessary technique for analysis of the structural deviation closely relating to a very high venous pressure.
Analytical scanning electron microscopy for solid surface
Authors: Ichinokawa T. 
Published: February 2005

AbstractA scanning electron microscope of ultra‐high‐vacuum (UHV‐SEM) with a field emission gun (FEG) is operated at the primary electron energies of from 100 eV to 3 keV. The instrument can form the images that contain information on surface chemical composition, chemical bonding state (electronic structure), and surface crystal structure in a microscopic resolution of several hundred angstroms (Å) using the techniques of scanning Auger electron microscope, scanning electron energy loss microscope, and scanning low‐energy electron diffraction (LEED) microscope. A scanning tunneling microscope (STM) also has been combined with the SEM in order to obtain the atomic resolution for the solid surface.The instrumentation and examples of their applications are presented both for scanning LEED microscopy and STM.
High‐resolution electron microscopy study on crystal structures of high‐Tc superconductors
Authors: Hiraga Kenji , Oku Takeo , Shindo Daisuke , Hirabayashi Makoto 
Published: February 2005

AbstractRecent studies of high‐resolution electron microscopy on the high‐Tc superconductors of Y‐Ba‐Cu‐O and Bi‐Ca‐Sr‐Cu‐O are presented. The observed images of crystals thinner than 3 nm, taken under conditions that approached the Scherzer defocus condition, directly show the arrangements of cations and oxygen‐vacant positions. The results reveal structural characteristics of the atomic scale; this offers important insights into the origin of the high‐Tc superconductivity. The usefulness of high‐resolution electron microscopy for studying complicated crystal structures is demonstrated for the high‐Tc oxides.
Ultrastructural demonstration of exocytosis in the intact rat adrenal medulla
Authors: Carmichael Stephen W. , Brooks Jack C. , Malhotra Ravi K. , Wakade Taruna D. , Wakade Arun R. 
Published: February 2005

AbstractEvidence is presented for morphological proof of exocytosis in the rat adrenal medulla in situ. Techniques were modified to allow perfusion of the intact adrenal gland with secretagogues (or electrical stimulation) followed by tannic acid. Unstimulated specimens demonstrated exocytotic (omega‐shaped) profiles filled with flocculent material. This flocculation was also seen in the intercellular space. Stimulation of the adrenal medulla also resulted in the appearance of exocytotic profiles and an accumulation of the flocculent mass. This was often most evident in the subendothelial space. This is the first demonstration of exocytosis in the rat adrenal medulla by electron microscopy. The techniques used in this study will be useful for studying the pathway of secretory products of the adrenal chromaffin cell before they enter the vascular system.