bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of adrenal reticularis and Sertoli cells in sterile male mice
Authors: White Yvonne , Hoage Terrell , Turner Jack , Bishop Jack 
Published: June 2020

Heterozygous translocations have been established as a cause of male infertility in mice. Previous studies did not establish a relationship between translocations and hormonal control of fertility in males. We examined the adrenal-zona-reticularis-cell/Sertoli cell hormonal axis in sterile male mice that had chromosomal translocations induced by triethylenemel amine (TEM). Out of 397 male offspring of TEM treated CD1 males and F1 (C57BL/6J x BALB/c) females 26 were found to be infertile and confirmed as translocation carriers by cytogenetic analysis of testicular tissue acquired by unilateral orchiectomy at 11 - 13 months of age. Radioimmunoassay of blood serum testosterone collected between 14 and 18 months of age showed the sterile males to vary from 0.96 ± 0.41 to 10.55 ± 1.65 ng/ml compared to 3.17 ± 0.55 ng/ml in fertile controls.Adrenal and testicular tissues were collected from ether-anesthetized animals at 18 months of age. Two or three animals were selected to represent each group: non-translocation controls, and translocation groups with high serum testosterone (HT), medial serum testosterone (MT) and low serum testosterone (LT).
Examination of a liver cell line tumorigenically transformed by DL-ethionine
Authors: Junker J.L. , Wilson M.J. , Munoz E.F. , Heine U.I. 
Published: June 2020

A nontumorigenic cell line derived from rat hepatocytes became tumorigenic subsequent to its cultivation for 3 months in medium containing 7.5 mM DL ethionine. We used light and electron microscopy in order to observe the structural effects of this treatment. At confluence, both experimental and control cultures appeared as monolayers of contiguous polygonal cells. Subconfluent cultures of ethionine-treated cells had a minor population of elongated cells, with extended cytoplasmic processes, which were not seen in control cultures. Actin cables (visualized with a NBD-phallacidin probe), which were routinely visible in polygonal cells, were not as pronounced in elongated cells (Fig. 1). Likewise, the arrangement of microtubules (stained with FITC-antitubulin) was characteristically altered from a mainly circumferential distribution at the periphery of the cytoplasm in polygonal cells to longitudinal arrays in elongated cells.Examination by transmission electron microscopy of confluent cell cultures revealed a marked decrease in the length of desmosomal contacts between ethionine-treated cells accompanied by an increase in extracellular fibrillar material (Fig. 2).
Altered thymic epithelial cells may be decisive for Moloney virus-induced lymphoma development
Authors: Heine U.I. , Krueger G.R.F. , Munoz E. , Karpinski A. 
Published: June 2020

Infection of newborn mice with Moloney leukemia virus (M-MuLV) causes a T-cell differentiation block in the thymic cortex accompanied by proliferation and accumulation of prethymic lymphoblasts in the thymus and subsequent spreading of these cells to generate systemic lymphoma. Current evidence shows that thymic reticular epithelial cells (REC) provide a microenvironment necessary for the maturation of prethymic lymphoblasts to mature T-lymphocytes by secretion of various thymic factors. A change in that environment due to infection of REC by virus could be decisive for the failure of lymphoblasts to mature and thus contribute to lymphoma development.We have studied the morphology and distribution of the major thymic cell populations at different stages of tumorigenesis in Balb/c mice infected when newborn with 0.2ml M-MuLV suspension, 6.8 log FFU/ml. Thymic tissue taken at 1-2 weekly intervals up to tumor development was processed for light and electron microscopy, using glutaraldehyde-OsO4fixation and Epon-Araldite embedding.
The effect of hypertension on the internal elastic lamina of rat portal vein
Authors: Sweitzer Kirby L. 
Published: June 2020

Previous studies of systemic and portal hypertension have reported an increase in the elastic tissue component. However, there is no mention of conformational alterations in the elastic network beyond reduplication of the internal elastic lamina in rabbit inferior vena cava. This experiment was designed to study the configurational alterations in the internal elastic lamina (IEL) of hypertensive hepatic portal vein of the rat.Twenty-one male Sprague-Dawley rats, approximately the same age and weight, were divided into three groups. Group A consisted of five normal controls which had not undergone surgery. Group B consisted of seven sham control rats which had a laparotomy, but the portal vein was not ligated. Group C consisted of nine experimental rats which had the portal vein partially ligated to create a stenosis. The portal vein was removed eight weeks after laparotomy. The elastic network was then exposed by removal of the nonelastic components by sonication in 0.5N sodium hydroxide and autoclaving. The tissue was fixed in Karnovsky's fluid with a phosphate buffer and routinely prepared for SEM observation.
A comparison of two indirect immune electron microscopy procedures using monoclonal antibody to localize specific African swine fever virus (ASFV) proteins in infected cells and virus
Authors: Letchworth III G. J. , Whyard T. C. , Wool S. H. 
Published: June 2020

The primary purpose of this study was to devise a procedure in which a large number of monoclonal antibodies could be tested against several African swine fever virus (ASFV) preparations (virus, infected cells). The procedure had to be rapid, use a small sample and provide for some TEM.Monoclonal antibodies were produced by standard methods using myeloma cells and lymphocytes from mice immunized against ASF viral proteins. Antibodies were characterized by immunoprecipitation of radio-labelled viral proteins (Fig 1).The viral preparations used in this study were either infected macrophages, culture fluid supernatant from ASFV-infected macrophages or red blood cells from infected pigs. Each of the three viral preparations was tested by two indirect immune electron microscopy (IEM) methods; a grid method and a test tube method. In the grid method, formvar coated grids were floated on a viral preparation then for one hour each on the mouse monoclonal antibody and finally on ferritin tagged sheep anti-mouse IgG with washes between each step.
Structural and morphometric studies of liver in a ferret model of Reye's syndrome
Authors: Gray R. H. , Deshmukh D. R. , Maassab H. F. , Robertson D. G. , de la Iglesia F. A. 
Published: June 2020

The etiology of Reye's Syndrome (RS) in children is unknown and the syndrome is preceeded by a viral infection. In addition, environmental agents, such as pesticides have been implicated as etiological factors for RS and recent epidemiological studies suggested that aspirin may predispose towards RS. In a recently developed animal model for RS, the subcellular liver changes of ferrets infected with influenza B virus, treated with aspirin and fed an arginine deficient (AD) diet have been studied.Eight week old, male, sable-coated ferrets were used in the study. All animals were fed Purina Cat Chow until the fasting period. Experimental animals were infected intranasally with influenza B on day 1 as previously described, and on the evening of the first day, aspirin (50mg/kg) dosing was started and continued twice daily for 3 days. Control and experimental groups were fasted overnight, and on the fourth day at 9:00 AM, the controls were given Purina Cat Chow while the experimental group was given the AD diet.
Alcaligenes fecalis infected tracheal epithelium: An ultrastructural study
Authors: Renee Finer Kim 
Published: June 2020

Alcaligenes fecalis is a gram negative bacterium previously thought to be nonpathogenic for humans and animals. The organism is commonly isolated in the gastrointestinal tract. In 1978 it was proven that A. fecalis was the etiologic agent of turkey coryza, an upper respiratory disease of young poults.The infectivity of A. fecalis in the upper respiratory tract suggests that the bacterium has altered its tissue tropism and developed a mechanism of adherence enabling colonization of the tracheal epithelium in spite of the muco-ciliary clearing mechanisms of the trachea. The purpose of this work was to examine the adherence of A. fecalis to the tracheal epithelium and to characterize the host cell response to infection.One day old poults were infected intranasally with either 108 colony forming units of A. fecalis, Wampler, or, as a control, 0.5 ml of sterile brain heart infusion broth. For TEM, the cranial portion of the trachea was cut into 2 mm2 sections, fixed in 2.5% glutaraldehyde, post-fixed in 1% OsO4, dehydrated in ethanol, and embedded in Epon-Araldite. Thin sections were stained with uranyl acetate and Sato's lead. For SEM, tracheal sections were fixed in glutaraldehyde, dehydrated in ethanol, critical point dried, and coated with 250 Å of gold-palladium.
Electron microscopic studies of fiber degradation by rumen fungi
Authors: Akin Danny E. 
Published: June 2020

The rumen microbial population is a complex ecosystem. Bacteria, protozoa, and fungi all play a part in degrading plant cell walls, which are a major substrate for energy and protein for the host animal. Rumen bacteria are considered to be the major degraders of forage fiber, but recent research has shown that rumen fungi are ubiquitous and are able to attack plant cell walls. Electron microscopy has been important in delineating the roles played by the various microbial types, including the fungi. The object of the present research was to assess the role of rumen fungi as degraders of particular tissues and to demonstrate that the presence of rumen fungi in the rumen can explain many of the unusual morphotypes associated with degradation of the more resistant tissues in forages.Rumen fungi were evaluated by inoculating tubes containing leaf blade sections of Cynodon dactyl on in a semi-synthetic, anaerobic medium with rumen fluid and incubating the tubes for 48 hours at 39°C. Some of the tubes contained streptomycin (2 mg/ml) and penicillin (2 x 10 units/ml) to inhibit bacteria.
Diffraction, Imaging and the Microscopic World of Materials
Authors: Thomas G. , Clarke D. R. , Gronsky R. 
Published: June 2020

Brief History - Probably no other technique has had quite the dramatic impact upon materials science and engineering as has the combination of electron diffraction and microscopy. The development of the modern electron microscope is an unusual outcome of wide and diverse series of experimental discoveries and theoretical concepts amongst which certainly the elegant Nobel Prize winning (1937) diffraction experiments of Davisson and Germer and Thomson ranks as one of the most significant.Although the first electron microscope was developed in Berlin, a North American instrument was built in 1939 at the University of Toronto. Soon after in 1941, RCA produced the first commercial microscopes in the USA. At first, the principal technique of sample preparation was replication, until Heidenreich at Bell Labs, maintaining the electron diffraction tradition set by Davisson, and later, Heidenreich and Sturkey, paved the way for modern thin foil microscopy with their dynamical electron diffraction theory. This accounted for the interference effects observed in images of crystals.
Crystal Structure Determination of Glycerol-Containing Lipids from Electron Diffraction Data. Use of Analog Compounds Based upon Configurational Isomers of Cyclopentane-1, 2, 3-TRIOL
Authors: Dorset Douglas L. , Hancock Anthony J. 
Published: June 2020

Lipids containing long polymethylene chains were among the first compounds subjected to electron diffraction structure analysis. It was only recently realized, however, that various distortions of thin lipid microcrystal plates, e.g. bends, polar group and methyl end plane disorders, etc. (1-3), restrict coherent scattering to the methylene subcell alone, particularly if undistorted molecular layers have well-defined end planes. Thus,ab initiocrystal structure determination on a given single uncharacterized natural lipid using electron diffraction data can only hope to identify the subcell packing and the chain axis orientation with respect to the crystal surface. In lipids based on glycerol, for example, conformations of long chains and polar groups about the C-C bonds of this moiety still would remain unknown.One possible means of surmounting this difficulty is to investigate structural analogs of the material of interest in conjunction with the natural compound itself. Suitable analogs to the glycerol lipids are compounds based on the three configurational isomers of cyclopentane-1,2,3-triol shown in Fig. 1, in which three rotameric forms of the natural glycerol derivatives are fixed by the ring structure (4-7).
Microstructure of 316 Stainless Steel Cladding from a Fuel Pin Irradiated in EBR-II
Authors: Berting F. M. 
Published: June 2020

Swelling of the stainless steel cladding which contains the fuel in nuclear reactors is a well-known phenomenon. Efforts to minimize the swelling and prolong the life of the fuel pins depends on understanding the mechanisms by which swelling occurs. Study of the microstructural damage caused by neutron irradiation of the 316 stainless steel currently used in cladding is an important part of the investigation of the swelling mechanisms. Most of the microstructural investigations of swelling phenomena to date have been performed on material irradiated in isothermal capsules that eliminate contact between the samples and the fuel.This report is concerned with the steel actually used to contain the fuel pellets for a normal lifetime in-reactor. The pin cladding experienced the full range of temperatures and fluences characteristic of the 13.5" long reactor core. The conditions of irradiation for the fuel pin studied are shown in Figure 1(a), where temperature rises steadily from bottom to top of the pin and fluence reaches a peak at about core center.
Image Enhancement, Micrograph Screening, and Teaching Principles of Contrast with a High Resolution Closed Circuit Television System
Authors: Cohen Arthur L. , Steever R.G.E. 
Published: June 2020

For several years we have been using a closed circuit television system consisting of a high resolution camera (1000 lines), monitor, mount, incident lighting for prints, a light box for negatives with cooling fan and silicon controlled rectifier (SCR) for controlling light intensity. This assembly (Fig. 1) has the following controls: spatial inversion (right-left, top-bottom), image inversion (negative-positive), image height and width, brightness, and contrast. Other image controls (gain, target, pedestal) are infrequently needed. Contrast and tonal range may be widely varied; negatives may be viewed as positives, distortion (as in scanning microscopy) may be corrected, and image size may be adjusted.The system is useful for: (1) Screening negatives for suitability of print ing by displaying them as positives (i.e. simulated prints) thus obtaining an idea of the degree of contrast desired. (2) Extracting the maximum information from a negative.
Experimental High Resolution Dark Field Electron Microscopy
Authors: Pierce Larry , Buseck Peter R. 
Published: June 2020

High resolution dark field (DF) images of the superstructures of the pyrrhotite (Fe1-xS) and bornite-digenite (Cu5FeS4-Cu9S5) series can be related to structure. Further, they provide more detail than bright field (BF) images. The same objective aperture size and stigmater settings were used for DF as for BF imaging; symmetrical arrangements of diffracted beams in the objective aperture were used. Images that can be related to structure were obtained at the defocus value giving the greatest image contrast, thereby enabling proper defocusing without requiring extensive through-focus series.For the minerals of interest, diffraction patterns consist of many superstructure reflections and a few subcell reflections. BF images contain primarily features of the superstructure, presumably because the subcell reflections fall far from the axis of the objective lens and thus are affected by spherical and chromatic aberrations and beam divergence. Likewise, DF images formed with a similar arrangement of beams as that in BF contain only features of superstructure, but with reverse contrast to BF.
Characterization Of Chrysotile Asbestos In Automobile Brake Drum Dust By Transmission Electron Microscopy (TEM)
Authors: Seshan Krishna , Smith Glenn R. 
Published: June 2020

This study supports other work that automobile brake drum dust is a source of partially altered and unaltered chrysotile asbestos (1-3) and suggests that dark-field electron microscopy could be used to identify the source of the fibres. These results are in contradiction to those who report that high temperatures reached during braking reduce a majority of the chrysotile to forsterite (4,5).Automobile brake drum dust was directly transferred to formvar coated grids and coated with carbon on both sides. The grids were then examined with a Siemens 1A and a Philips 301 at 100 kV.Intact chrysotile fibre bundles with some phenolic opaque binder is shown in Fig. 1 displaying partially deformed internal canals, but does not show gross morphological change. Unaltered chrysotile is shown in Fig. 2a and was confirmed by selected area electron diffraction (SAED), see Fig. 2.
Beam Enhanced Oxidation Of Fe-20%A1 In A Transmission Electron Microscope
Authors: Dahmen Ulrich 
Published: June 2020

In spite of the common use of high voltage electron microscopy for studies of radiation damage in metals, the effect of a conventional 100 kV electron beam on the morphology and diffraction phenomena of thin metal foils has been widely neglected. The present paper calls attention to the importance of beam enhanced oxidation as a source of serious misinterpretation of electron micrographs. A variety of techniques of electron microscopy will be used to demonstrate the growth and morphology of oxides on thin foils. Although this study is limited to FeAl, spontaneous or beam enhanced oxidation are observed in a number of systems (1,2).Figure 1 shows a high density of small domains that have grown in the limited area exposed to the beam. These domainsocan be identified as an fee oxide phase with a lattice parameter of ∽8.1Å, in epitaxy with the matrix. The observed orientation relationship is of the Nishiyama- Wassermann type (3).
Trends in Electron Energy Loss Spectroscopy
Authors: Colliex C. , Trebbia P. 
Published: June 2020

The physical foundations for the use of electron energy loss spectroscopy towards analytical purposes, seem now rather well established and have been extensively discussed through recent publications. In this brief review we intend only to mention most recent developments in this field, which became available to our knowledge. We derive also some lines of discussion to define more clearly the limits of this analytical technique in materials science problems.The spectral information carried in both low ( 0<ΔE<100eV ) and high ( >100eV ) energy regions of the loss spectrum, is capable to provide quantitative results. Spectrometers have therefore been designed to work with all kinds of electron microscopes and to cover large energy ranges for the detection of inelastically scattered electrons (for instance the L-edge of molybdenum at 2500eV has been measured by van Zuylen with primary electrons of 80 kV). It is rather easy to fix a post-specimen magnetic optics on a STEM, but Crewe has recently underlined that great care should be devoted to optimize the collecting power and the energy resolution of the whole system.
Data Acquisition and Handling Unit for a Quantitative Use of Electron Energy
Loss Spectroscopy
Authors: Trebbia P. , Ballongue P. , Colliex C. 
Published: June 2020

An effective use of electron energy loss spectroscopy for chemical characterization of selected areas in the electron microscope can only be achieved with the development of quantitative measurements capabilities.The experimental assembly, which is sketched in Fig.l, has therefore been carried out. It comprises four main elements.The analytical transmission electron microscope is a conventional microscope fitted with a Castaing and Henry dispersive unit (magnetic prism and electrostatic mirror). Recent modifications include the improvement of the vacuum in the specimen chamber (below 10-6 torr) and the adaptation of a new electrostatic mirror.The detection system, similar to the one described by Hermann et al (1), is located in a separate chamber below the fluorescent screen which visualizes the energy loss spectrum. Variable apertures select the electrons, which have lost an energy AE within an energy window smaller than 1 eV, in front of a surface barrier solid state detector RTC BPY 52 100 S.Q. The saw tooth signal delivered by a charge sensitive preamplifier (decay time of 5.10-5 S) is amplified, shaped into a gaussian profile through an active filter and counted by a single channel analyser.
Suppression of γ’ Precipitation in a Laser-Melted Nickel-Base Alloy
Authors: Walsh J. M. , Whittles J. C. , Kear B. H. , Breinan E. M. 
Published: June 2020

Conventionally cast γ’ precipitation hardened nickel-base superalloys possess well-defined dendritic structures and normally exhibit pronounced segregation. Splat quenched, or rapidly solidified alloys, on the other hand, show little or no evidence for phase decomposition and markedly reduced segregation. In what follows, it is shown that comparable results have been obtained in superalloys processed by the LASERGLAZE™ method.In laser glazing, a sharply focused laser beam is traversed across the material surface at a rate that induces surface localized melting, while avoiding significant surface vaporization. Under these conditions, computations of the average cooling rate can be made with confidence, since intimate contact between the melt and the self-substrate ensures that the heat transfer coefficient is reproducibly constant (h=∞ for perfect contact) in contrast to the variable h characteristic of splat quenching. Results of such computations for pure nickel are presented in Fig. 1, which shows that there is a maximum cooling rate for a given absorbed power density, corresponding to the limiting case in which melt depth approaches zero.
Electron Microscopic Observations of Deformation Substructures in Polycrystalline Titanium Containing Rare-Earth Additives
Authors: O'Neal J. E. , Lederich R. J. , Sastry S. M. L. 
Published: June 2020

The addition of small amounts of erbium to titanium results in a uniform dispersion of 20-60 nm diam particles in the Ti matrix. The presence of such fine dispersoids effects significant grain-refinement and grain-growth- retardation at elevated temperatures (1). Results of a thin-foil, transmission-electron-microscopic study of the influence of Er dispersoids on the development of dislocation substructure during tensile deformation are reported here.Figure la shows the dislocation arrangement in Ti-O.lEr deformed at 293 K to a strain ≈ 0.40. The structure consists of well-defined cells, with the cell walls aligned parallel to <l2l0> directions. The average spacing of cells in the <I2I0> directions is ≈ 0.5 μm. Dispersoids are located both at the cell boundaries (as at A in Fig. la) and within the cells (as at B). Dis- persoid-free Ti that is similarly strained develops a coarser cell structure with an average cell spacing ≈ 1 μm (Fig. lb).