bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dual Stage SEM with thermal field-emission gun
Authors: Yamazaki S. , Sato T. , Aota S. , Buchanan R. 
Published: June 2020

Resolution improvement is an on-going goal in scanning electron microscope development. High resolution is required at both high and low accelerating voltages in a wide field of applications, including, but not exclusive to, semiconductors and new materials development. Two approaches which result in improved resolution through-out the operating voltage range of the SEM are 1) the adoption of low aberration objective lenses, and 2) the use of high brightness electron sources.The DS-130F SEM which is described here uses a high brightness thermal field emission gun (TFEG) in conjunction with a modified DS-130 column. The electron optical configuration is quite unique, as it includes two independent stages. The top stage places the sample within a high field strength low aberration objective lens, resulting in ultra high resolution on samples up to 18 x 8 mm. The bottom stage accommodates 6” samples and uses a second dedicated conical objective lens allowing a short working distance to be maintained on tilted samples.
Absorption corrections for AEM Analysis of thin-film and sphere samples with large-solid-angle x-ray detectors
Authors: Zreiba Nuri A. , Kelly Thomas F. 
Published: June 2020

Recent advances in x-ray detectors for TEM and STEM instruments have resulted in large increases in the solid angle that these detectors subtend with respect to the sample. These solid angles of order 0.2 steradian mean that x rays emitted into a cone of semi-angle equal to 15° will be intercepted by the detector. Since the conventional absorption correction for x-ray analysis assumes that all detected rays are parallel, we chose to examine whether divergent x rays could change the absorption and fluorescence corrections significantly and should therefore be taken into account.This paper will focus on the effects of such changes on the absorption correction of thin specimens. Two specimen geometries will be considered, namely the usual plane parallel slab and the sphere geometry. Sphere geometries are of interest because they are currently used in the evaluation of the efficiency of x-ray detectors, the results of which are to be presented in the X-ray Optics and Microanalysis Conference in Poland this summer.
X-Ray absorption edge elemental imaging of B. thuringienis
Authors: Stears R. L. 
Published: June 2020

Because of the nature of the bacterial endospore, little work has been done on analyzing their elemental distribution and composition in the intact, living, hydrated state. The majority of the qualitative analysis entailed intensive disruption and processing of the endospores, which effects their cellular integrity and composition.Absorption edge imaging permits elemental analysis of hydrated, unstained specimens at high resolution. By taking advantage of differential absorption of x-ray photons in regions of varying elemental composition, and using a high brightness, tuneable synchrotron source to obtain monochromatic x-rays, contact x-ray micrographs can be made of unfixed, intact endospores that reveal sites of elemental localization. This study presents new data demonstrating the application of x-ray absorption edge imaging to produce elemental information about nitrogen (N) and calcium (Ca) localization using Bacillus thuringiensis as the test specimen.
Ultrathin silicon membrane thickness determination by CBED and measurement of plasmon mean free path
Authors: Xu Peirong 
Published: June 2020

The lower limit of accurate thickness measurement using two beam CBED patterns is usually about one extinction distance for the reflection used. We have used (111) symmetric CBED patterns to measure thin silicon membrane thicknesses as low as 130 Å by comparing experimental patterns with computer simulated CBED patterns. The silicon plasmon mean free path was also measured using these thickness values.Symmetric convergent beam diffraction patterns of (111) silicon in the thickness range of 130 Å to 1300 Å were obtained in a VG HB501A STEM with a 5 Å probe (8 mrad convergence angle) scanning a 100 Å × 100 Å area. The sample was made by ion implantation, anodic etching and annealing. Subsequent photolithography and reactive ion etching thinned the specimen down further to as thin as 100 Å. The sample was chemically cleaned by the Shiraki method before being loaded into the microscope.
The relaxation of compressive biaxial strains in SOS via microtwins
Authors: Twigg M. E. , Richmond E. D. , Pellegrino J. G. 
Published: June 2020

For heteroepitaxial systems, such as silicon on sapphire (SOS), microtwins occur in significant numbers and are thought to contribute to strain relief in the silicon thin film. The size of this contribution can be assessed from TEM measurements, of the differential volume fraction of microtwins, dV/dν (the derivative of the microtwin volume V with respect to the film volume ν), for SOS grown by both chemical vapor deposition (CVD) and molecular beam epitaxy (MBE).In a (001) silicon thin film subjected to compressive stress along the [100] axis , this stress can be relieved by four twinning systems: a/6[211]/( lll), a/6(21l]/(l1l), a/6[21l] /( l1l), and a/6(2ll)/(1ll).3 For the a/6[211]/(1ll) system, the glide of a single a/6[2ll] twinning partial dislocation draws the two halves of the crystal, separated by the microtwin, closer together by a/3.
A comparative HVEM study of ICB-deposited aluminum films
Authors: Westmacott K.H. , Dahmen U. 
Published: June 2020

The Ionized Cluster Beam (ICB) technique pioneered by Takagi and colleagues in Kyoto is an exciting new method for depositing thin films possessing novel microstructures and unusual properties, (see for example Ref. 1 for a review of recent work). These materials are of interest not only for their potential use in electronic applications but also because of their eminent suitability for fundamental high resolution studies of grain boundary structureThe HVEM's at the National Center for Electron Microscopy are employed in a complementary fashion to characterize fully the microstructure of ICB deposited Al films. In-situ annealing studies of the films are conducted in the 1.5 MeV Kratos HVEM taking advantage of its heating stage, excellent specimen chamber vacuum (10-8 torr), and high resolution video camera. The increased penetration at 1.5 MeV allows different film thicknesses of Al film to be examined as well as the regions of the foil where the silicon substrate remains backing the Al film. High resolution studies of the atomic structure of grain boundaries are performed on the 1 MeV JEOL ARM using its unique tilting stage and ability to image structures at the 0.15 nm level.
Analyzing kinesin and cytoplasmic-dynein driven movement with nanometer precision
Authors: Schnapp B.J. , Gelles J. , Steuer E. , Sheetz M. P. 
Published: June 2020

Kinesin and cytoplasmic dynein are microtubule-based, force-generating ATPases thought to be involved in the bidirectional transport of vesicular organelles along microtubules. In vitro, kinesin and dynein promote movement of 0.1 - 0.2μm plastic beads toward the plus and minus ends, respectively, of microtubules. In these systems, the proteins are thought to remain fixed, by nonspecific absorption, to the bead surface. The motion of the bead on the microtubule is detected by video enhanced, DIC microscopy, and reflects the movement of the motor protein along the microtubule.To quantitate bead motion, a method was devised for tracking the position of kinesin or dynein coated beads moving along microtubules. The method involves 1) cross-correlation of a template bead image (the kernal) with each of the frames in a video sequence, followed by 2) calculation of the centroid of the cross-correlation function for each of the frames in the sequence. The centroid provides a measure of bead position. Application of this method to the measurement of the relative position of two stationary beads adsorbed nonspecifically to the glass surface indicates that the standard deviation of the measured horizontal and vertical coordinates can be less than 0.5 nm. More recently, we have determined that centroid calculation of the unprocessed bead image (i.e. without cross-correlation) can provide a measure of bead position with standard deviations in the horizontal and vertical directions of less than 2 nm. The latter method is faster, but more sensitive to the contrast and magnification of the video image.
Correlative light, scanning and Transmission Electron Microscopy of polyethylene glycol (PEG) embedded and subsequently de-embedded tissues
Authors: Kondo Hisatake 
Published: June 2020

Our understanding of the detailed morphology of bioloqical specimens often requires the correlation between images of the surface by scanning electron microscopy (SEM) and of the underlining interior structure by light microscopy (LM) or transmission electron microscopy (TEM). In order to accomplish the correlation with high quality, the polyethylene glycol (PEG) embedding and subsequent deembedding has been revealed to be a simple and quite reliable procedure.Tissue or cell samples are fixed and dehydrated in ethanol according to the conventional procedures. Vials containing the specimens in 100% ethanol are warmed in an oven at about 60°C and approximately equal amount of pure molten PEG-4000 is added in the vials. PEG is easily dissolved by gentle agitation. Thereafter the specimens are transferred to pure molten PEG contained in well-dried gelatin capsules. After the specimens have been sunk to the bottom of the capsule, each capsule is immersed in liquid nitrogen to solidify PEG. Portions of the solidified PEG including the specimens are cut out with a razer blade and mounted with dental wax on supporting stubs fitting the collet of the microtome. The specimen blocks are sectioned with a well-dried glass or diamond knife. Wrinkle-free sections, 200-300 nm thick, can be easily obtained with some practice unless the room atmosphere is humid. The sections are picked up with a platinum loop filled with 2.5 % sucrose and mounted on glass slides for LM or formvar-coated grids for TEM, both of which have previously been treated with 0.1 % poly-L-lysine. For LM sections may be processed for immunohistochemistry. For TEM, sections on grids are put into a submerged grid holder in 90 % ethanol. The holder is transferred to 100 % ethanol and subsequently to a critical point apparatus with carbon dioxide. For SEM, the specimen blocks with its mirror-smooth face, after taking sections, is removed from the stubs and immersed in warm water to get rid of PEG. The blocks are then dehydrated in ethanol and critical point dried with carbon dioxide.
Scanning and Transmission Electron Microscopic correlates of sulfur mustard (HD) toxicity
Authors: Petrali J.P. , Oglesby S.B. , Mills K.R. 
Published: June 2020

In spite of the many reports, since World War I no the pathology of mustard injury,
no ultrastructural studies were performed until our laboratory published a report on the ultrastructure of the pathogenesis of blister formation following exposure to sulfur mustard of human–skin grafted to congenitally athymic nude mice. This study afforded us the opportunity for the first time to focus on several objectives: 1) to further delineate the histopathology which had been noted at light microscopy levels; 2) to identify possible early mustard-induced morpho- logical changes which may occur during the latent asynptcamtic phase; and 3) to prcmote our understanding of the temporal features of mustard pathology with the expectation that prophylactic and therapeutic strategies might be morphologically predictable. We now have the opportunity to describe HD-induced pathology in cells-in-culture and compare them with that of the skin lesion of a human skin grafted model and a hairless guinea pig model.We used standardized ultrastructural technology to study by transmission and scanning electron microscopy the subcellular effects of HD on human skin grafted to athymic mice, human lyrrphocytes and human keratinocytes in culture, and, the hairless guinea pig model. While doses of mustard differed according to the dictates of individualized protocols, all specimens were gathered at 24-48 hours following exposure and were aldehyde fixed, dehydrated in graded ethanols and either embedded in epoxy resin for transmission electron microscopy or critical-point dried and sputter coated with gold-palladium for scanning electron microscopy.
Structure and function of nonorthodox chromatins: I. aggregation sensitivity of DNA is correlated to the Protein content of chromosomal material
Authors: Pelzer J. , Bohrmann B. , Johansen R. , Maeder M. , Gyalog R. , Arnold-Schulz-Gahmen B. , Villiger W. , Kellenberger E. 
Published: June 2020

Aggregation insensitive eukaryotic chromatin in which DNA is associated with histones can be crosslinked by all fixatives commonly used in electron microscopy. By crosslinking it becomes protected from aggregation during dehydration with organic solvents. This is not the case with most nonorthodox chromatins, where the ratio of protein to DNA is estimated to be 5 to 10 times lower and where the basic, acid-soluble proteins are rather different from the histones. The aggregation sensitivity of different chromatins is summarized in table 1.Nonorthodox aggregation sensitive chromatins were found in Eubacteria, bacteriophage- pools (fig. 1a,b), Cyanobacteria, mitochondria, and Dinoflagellates (fig. 2a,b). The latter organisms are of particular interest because of morphologic similarities to other flagellates like Euglena with its aggregation insensitive histone-containing chromosomes (fig. 3a,b). With respect to the distribution over the living world, nonorthodox chromatins might be more frequent than the histone-containing ones.
Structural analysis of ribosomal particles from Escherichia coli by STEM
Authors: Boublik M. , Mandiyan V. , Tumminia S. , Hainfeld J.F. , Wall J.S. 
Published: June 2020

Presently, dedicated scanning transmission electron microscopy (STEM) is the most direct, most versatile and least destructive electron microscopic technique for high resolution studies of biological specimens. Apart from the morphology (shape, characteristic dimensions) of biological macromolecules, STEM can provide quantitative information on their molecular mass, the mass distribution within individual particles (for calculation of the radius of gyration), and the topography of their individual macromolecular components and functional sites. Deposition of nucleic acid molecules under non-denaturing conditions opened the EM field for studies of their conformation under various ionic conditions, their interactions with other macromolecules, proteins in particular, and ultimately to the visualization of the total reconstitution process of macromolecular complexes from their constituents.The potential of high resolution STEM at Brookhaven National Laboratory (BNL) was applied to the study of structure-function relationships of ribosomal particles of Escherichia coli, minute but complex cellular organelles playing a fundamental role in protein synthesis.
Ultrastructural Localization Study of Carcinoembryonic Antigen (CEA) in Gastric Cancer: Immunoelectron Microscopic Observation
Authors: Yuming Dong , Guanglin Yang , Jifeng Wu , Xiaolin Chen 
Published: June 2020

On the basis of light microscopic observation, the ultrastructural localization of CEA in gastric cancer was studied by immunoelectron microscopic technique. The distribution of CEA in gastric cancer and its biological significance and the mechanism of abnormal distribution of CEA were further discussed.Among 104 surgically resected specimens of gastric cancer with PAP method at light microscopic level, the incidence of CEA(+) was 85.58%. All of mucinous carcinoma exhibited CEA(+). In tubular adenocarcinoma the incidence of CEA(+) showed a tendency to rising with the increase of degree of differentiation. In normal epithelia and intestinal metaplasia CEA was faintly present and was found only in the luminal surface. The CEA staining patterns in cancer cells were of three types--- cytoplasmic, membranous and weak reactive type. The ultrastructural localization of CEA in 14 cases of gastric cancer was studied by immunoelectron microscopic technique.There was a little or no CEA in the microvilli of normal epithelia. In intestinal metaplasia CEA was found on the microvilli of absorptive cells and among the mucus particles of goblet cells. In gastric cancer CEA was also distributed on the lateral and basal surface or even over the entire surface of cancer cells and lost their polarity completely. Many studies had proved that the alterations in surface glycoprotein were characteristic changes of tumor cells. The antigenic determinant of CEA was glycoprotein, so the alterations of tumor-associated surface glycoprotein opened up a new way for the diagnosis of tumors.
Pathologic Calcification and Cell Viability in Rat Allograft Heart Valves
Authors: Walters K.S. , Lupinetti F.M. , Cobb S. , Moore K.C. 
Published: June 2020

Aortic valve allografts are employed in the treatment of patients having aortic valve disease with no apparent rejection or need for immuno-suppression. However, it is unknown whether immunologic differences between donor and recipient affect the performance of the allograft. Because calcification is an important cause of allograft failure, this study was designed to observe the effects of histocompatibility on the degree of allograft calcification.Four groups of ten adult male Lewis rats per group received aortic valve allografts transplanted heterotopically into the abdominal aorta. The aortic valves were obtained from adult male Lewis rats, Brown Norway rats (BN), Fisher rats (F), and Lewis-Brown Norway-Fisher hybrids (LBNF). At 3, 6, 9, and 12 weeks following implantation, the valves were removed, rinsed in saline and washed free of salts using distilled water. They were then mounted to a specimen holder with Tissue-Tek O.C.T. compound and quick frozen in liquid nitrogen. Sections 8um thick, containing leaflet, were cut using a Reichert-Jung cryostat at -20°C and mounted on carbon stubs.
Projection of antennal receptor cell into subesophageal ganglion in insect
Authors: Lee Bong-Hee , Kim Min-Yung , Kim Woo-Kap 
Published: June 2020

This investigation has been carried out to observe different types of synaptic organizations in subesophageal ganglion of Pieris rapae, then to examine the ultrastructure of degenerated antennal receptor terminals in ipsilateral subesophageal ganglion following the removal of an left antenna, and finally to identify which type of synapse is constituted in the subesophageal ganglion by the axon terminal of the receptor cell projecting from the antenna.For electron microscopy of normal synaptic organizations in the subesophageal ganglion, the general anesthesia of the one-day-old cabbage butterflies was performed in keeping them at 4°C for about 30 min. Thereafter, the heads were cut off from the butterflies with a razor blade and prefixed in 1% paraformaldehyde-1% glutaraldehyde at 4°C for 1 h. After being prefixed for 1 h, the heads were dissected under the stereoscope for getting the intact brains. The brains continued to be kept in a new prefixative at 4°C overnight of completing the fixation. They were washed in 0.4M phosphate buffer, pH 7.4, containing 7% glucose and 0.5% CaCl2, and postfixed in 2% OsO4 in phosphate buffer at 4°C for 2 h.
The proventriculus of the worker honeybee and its differentiation
Authors: Anna Pabst Maria , Crailsheim Karl 
Published: June 2020

The proventriculus (pv) of the honeybee regulates the flow of food from the crop into the midgut. It is a formation of the foregut intervening between the crop and the midgut and consists of four bulging pv folds forming a x-shaped lumen. At their ends (=lips) the folds bear filiform hairs forming a comb at their inner margins. The pv folds are lined by a sclerotized cuticular intima. Between the basal plates of the pv folds and at the outside of the organ a flexible cuticle is present. By gulping movements (inner longitudinal and outer circular muscle layer) and with the aid of the hairs it can separate liquid food from pollen grains.Studies were made of 4- and 6-7-day-old pupae and of foragers (Apis mellifera L.) Scanning electron microscopic preparations show that in 4-day-old pupae the pv is already present in its basic form. The lips have filiform hairs which are repeatedly split at their ends and spine-like hairs on the outer side of the lips.
Involvement of GER in Friend leukemia virus assembly in high-pressure frozen cells
Authors: Djaczenko W. , Müller M. , Benedetto A. , Carbone G. 
Published: June 2020

A thickening of ER membranes in murine myeloma cells was attributed by de Harven to the assembly of intracisternal virus particles. We observed similar thickening of GER membranes in Friend leukemia cells (FLC) apparently associated with Friend leukemia virus (FLV) assembly. We reinvestigated the problem of GER involvement in FLV assembly using high pressure cryofixed FLC.FLC (745A clone growing in suspension and FF clone growing in monolayer) were immersed in Hexadecene (Fluka, Switzerland) and rapidly frozen in Balzers HPM 010 freezing machine working at 2200 bar. All cells were freeze substituted at -90°C in 2% OsO4 in absolute acetone. Serial sections cut to avoid misinterpretations due to the geometry of sections, were collected on carbon coated 100 mesh grids.
Ultrastructure of mycelial conidia of Paracoccidioides brasiliensis
Authors: Samsonoff William A. , Edwards Mercedes R. , Restrepo-Moreno A. 
Published: June 2020

Paracoccidioides brasiliensis, the causative agent of an endemic South American mycosis, displays two growth phases: at 37°C, in infected tissues or in artificial media, it grows as a pleomorphic multi-budding yeast; at 25°C it becomes a mycelium with septate branched hyphae. Both the yeast and mycelial cells have been characterized by light microscopy. Under proper conditions, the mycelia produce a variety of sporogenous cells, for which only light-microscopy descriptions exist. This report details the ultrastructure of these cells (conidia) as seen by scanning (SEM) and transmission (TEM) electron microscopy.Mycelia of P. brasiliensis were fixed with formaldehyde and glutaraldehyde (1%-3% each) in cacodylate buffer (pH 7.2) at room temperature, stored in buffer at 4°C, and post-fixed with 1% osmium tetroxide.
Ultrastructure of rhinosporidiosis
Authors: Bharati Arumugam Sarasa , Arumugam S. , Sundaram A. , Rajalakshmi Y. 
Published: June 2020

Rhinosporidiosis is an unique fungal disease in that it has constantly eluded all efforts to culture the organism in vitro. Thus its exact life cycle is unknown, besides its various other biological characteristics. With this in view a study undertaken of the 54 cases showed the following L.M. and E.M. features.Light Microscopy: The fungi were seen to produce polypoid formations of fibrovascular connective tissue with a generally hyperplastic lining of squamous epithelium. The fungi themselves were in the form of multiple cysts of varying sizes and shapes. While most cysts appeared to be rounded or oval, tubular forms could also be seen. Sizes varied from 6-500 microns. The cyst wall appeared to have 2 layers, an inner cellulose and outer chitinous. The inner wall appeared associated with young spores and ovoid bodies 0.2 x 0.3 mm.