bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scanning Transmission Electron Microscopy Of Polymer Single Crystals
Authors: Krause S. J. , Allard L. F. , Bigelow W. C. 
Published: June 2020

Scanning transmission electron microscopy (STEM) has several advantages over conventional transmission electron microscopy (CTEM) for studying the structure of polymer single crystals. A major limitation in the electron microscopy of polymer single crystals is the rapid loss of diffraction contrast due to destruction of crystallinity by beam-induced cross-linking and/or chain scission. Electronic signal amplification, which is inherent in the STEM image forming system, allows images to be formed at lower incident beam dosages than required for photographic recording in the CTEM. This lowers the beam damage rate and routinely permits recording of bright field, dark field, and electron diffraction sequences, or alternatively, single images at high magnification for high resolution.An SEM operated in the STEM mode at voltages in the range from 20 to 50 KV will give good images of single crystals at magnifications up to 10,000X. An STEM operated at 100 KV with cold stage techniques further improves the imaging capabilities, since beam damage is reduced by 5 to 10 times with an increase in accelerating voltage and lower sample temperatures.1
Progress In The Practical Application Of Automated Image Analysis To Tem Negatives
Authors: Heckman F. A. , Redman E. , Connolly J.E. 
Published: June 2020

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.
Automated Image Analysis Of Nuclear And Cytoplasmic Changes In Exfoliated Cells From Tracheas Treated With Carcinogen
Authors: Stinson S.F. , Lilga J.C. , Sporn M.B. 
Published: June 2020

Increased nuclear size, resulting in an increase in the relative proportion of nuclear to cytoplasmic sizes, is an important morphologic criterion for the evaluation of neoplastic and pre-neoplastic cells. This paper describes investigations into the suitability of automated image analysis for quantitating changes in nuclear and cytoplasmic cross-sectional areas in exfoliated cells from tracheas treated with carcinogen.Neoplastic and pre-neoplastic lesions were induced in the tracheas of Syrian hamsters with the carcinogen N-methyl-N-nitrosourea. Cytology samples were collected intra-tracheally with a specially designed catheter (1) and stained by a modified Papanicolaou technique. Three cytology specimens were selected from animals with normal tracheas, 3 from animals with dysplastic changes, and 3 from animals with epidermoid carcinoma. One hundred randomly selected cells on each slide were analyzed with a Bausch and Lomb Pattern Analysis System automated image analyzer.
Effect of Grain Boundary Ledges on the Flow Stress in Nickel
Authors: Venkatesh Eswarahalli S. , Murr L.E. 
Published: June 2020

In a recent paper1 it was shown that grain boundary ledge structure can be changed by appropriate thermomechanical treatments. Grain boundary ledges are sources of dislocations2. Recently the effects of grain boundaries on the mechanical properties in metals and alloys were studied3,4. For a few years now the structure and properties of grain boundaries and their control have been considered as a means of strengthening polycrystalline materials5,6. Li5 has derived a Hall-Petch type relation in terms of grain boundary dislocation source (ledge) density, m, in the form where L is the grain size, σ0 and α are constants, and G ana b have the usual meaning. The influence of grain boundary ledge density, on the flow stress is considered in this paper.In the present work, pure (99.98%) nickel sheet mill rolled (hot) to 0.022 in. thick was used.
Scanning Electron Microscopy Studies of Volatile Transport within Particles During Knudsen Effusion Experiments
Authors: Schiffman R.A. 
Published: June 2020

During Knudsen effusion experiments on the nickel-rich, 2-phase region of the Ni-S system (Ni3S2+Ni) it was observed that the rate of effusion was not constant as expected but diminished with time. Investigation with a Hitachi Perkin-Elmer HHS-2R SEM, fitted with an Ortec energy dispersive X-ray analyzer, presented evidence that the falloff in vaporization rate was not due to diffusion, but the change in rate can be expected from the limitations inherent in the Knudsen experimental system.The starting material for these Knudsen effusion experiments, finely mixed NiS2 and sulfur, was placed in an effusion cell and heated at a constant temperature where sulfur, the more volatile component, effused. A mass spectrometer showed that S2 was the only effusing species over the entire Ni-S system within the 250-1100°C range investigated, as predicted.
Influence of X-Ray Induced Fluorescence on Energy Dispersive X-Ray Analysis of Thin Foils
Authors: Kenik E. A. , Bentley J. 
Published: June 2020

Cliff and Lorimer (1) have proposed a simple approach to thin foil x-ray analy sis based on the ratio of x-ray peak intensities. However, there are several experimental pitfalls which must be recognized in obtaining the desired x-ray intensities. Undesirable x-ray induced fluorescence of the specimen can result from various mechanisms and leads to x-ray intensities not characteristic of electron excitation and further results in incorrect intensity ratios.In measuring the x-ray intensity ratio for NiAl as a function of foil thickness, Zaluzec and Fraser (2) found the ratio was not constant for thicknesses where absorption could be neglected. They demonstrated that this effect originated from x-ray induced fluorescence by blocking the beam with lead foil. The primary x-rays arise in the illumination system and result in varying intensity ratios and a finite x-ray spectrum even when the specimen is not intercepting the electron beam, an ‘in-hole’ spectrum. We have developed a second technique for detecting x-ray induced fluorescence based on the magnitude of the ‘in-hole’ spectrum with different filament emission currents and condenser apertures.
The Fine Structure of the Sheath of Volvox Carteri f. Weismannia
Authors: Birchem Regina 
Published: June 2020

Spheroids of the green colonial algaVolvoxconsist of biflagellate Chlamydomonad-like cells embedded in a transparent sheath. The sheath, important as a substance through which metabolic materials, light, and the sexual inducer must pass to and from the cells, has been shown to have an ordered structure (1,2). It is composed of both protein and carbohydrate (3); studies ofV.rousseletiiindicate an outside layer of sulfated polysaccharides (4).Ultrastructural studies of the sheath material in developmental stages ofV.carterif.weismanniawere undertaken employing variations in the standard fixation procedure, ruthenium red, diaminobenzidine, and high voltage electron microscopy. Sheath formation begins after the completion of cell division and inversion of the daughter spheroids. Golgi, rough ER, and plasma membrane are actively involved in phases of sheath synthesis (Fig. 1). Six layers of ultrastructurally differentiated sheath material have been identified.
Immunoferritin Labelling of Intracellular Murine Mammary Tumor Virus After Thin Sectioning for Electron Microscopy
Authors: Weigand R.A. , Russo J. 
Published: June 2020

Simultaneous observation of viral particles and demonstration that they contain viral antigens has only recently been achieved. Most studies involve immunocytochemical labelling followed by embedding and thin sectioning and are limited to the study of budding particles at the cell surface (1). Most recently, methods for immunocytochemical labelling after thin sectioning have been developed. Hamilton (2) has applied these methods to detect murine mammary tumor virus (MuMTV) antigens in thin sections. The method used, however, does not allow simultaneous observation of viral ultrastructure and detection of the labelling product. Here we demonstrate the intracellular localization of a MuMTV antigen. Both the viral morphology and the immuno-ferritin label (labelled MuMTV antigen) can be observed simultaneously.Primary cultures obtained from a spontaneous mammary tumor of a C3H mouse were grown to confluency. The cultures were fixed as monolayers with cacodylate buffered 3l paraformaldehyde containing 0.05% glutaraldehyde. After dehydration, the monolayers were collected and embedded in Epon-Araldite.
Studies on Type B Virus Particles in Normal Prostate Tissues of Mice from High Mammary Cancer Strains
Authors: Ohtsuki Y. , Dmochowski L. , Seman G. , Bowen J. M. 
Published: June 2020

Normal prostate tissues of mice from ten different strains were examined by electron microscopy, in order to determine the presence of virus particles and also to ascertain whether prostatic glands were a potential source of infective oncornaviruses in mice. The observation of type B virus particles in normal prostate tissues of mice has already been reported. Our studies have been presently extended to a total of 61 mice. Type B virus particles (Fig. 1) and budding (Fig. 2) have been found in prostate tissues of 8 approximately 1 year old mice from all three high (C3H/Dm, RIII/Dm and A/Dm) and of one low (BALB/c/Dm) mammary cancer strain.Experiments have been carried out to characterize immunologically type B virus particles observed in the normal prostate tissues of mice of high mammary cancer strains. Frozen sections of prostate tissues from each of three 1 year old C3H/Dm and A/Dm strain mice were tested by fixed immunofluorescence (FIF) and by immunoelectron microscopy, using goat antiserum to mammary tumor virus (MTV) from A/Dm strain mouse milk.
Initial Polymerization Sites Indicated During Mitochondrial Oxidation of Diaminobenzidine after Toluene Treatment
Authors: Shannon W. A. , Matlib M. A. 
Published: June 2020

Numerous studies have dealt with the cytochemical localization of cytochrome oxidase via cytochrome c. More recent studies have dealt with indicating initial foci of this reaction by altering incubation pH (1) or postosmication procedure (2,3). The following study is an attempt to locate such foci by altering membrane permeability. It is thought that such alterations within the limits of maintaining morphological integrity of the membranes will ease the entry of exogenous substrates resulting in a much quicker oxidation and subsequently a more precise definition of the oxidative reaction.The diaminobenzidine (DAB) method of Seligman et al. (4) was used. Minced pieces of rat liver were incubated for 1 hr following toluene treatment (5,6). Experimental variations consisted of incubating fixed or unfixed tissues treated with toluene and unfixed tissues treated with toluene and subsequently fixed.
Morphological Characteristics of Mitochondria and Cultured Cells Made Permeable for Enzyme Studies
Authors: Shannog W. A. , Matlib M. A. , Robinson J. B. , Hochli M. , Srere P. A. 
Published: June 2020

Toluene has been used to make various cells permeable to exogenous substrates. More recently we have extended the method to heart and liver mitochondria (1,2). We reduced the toluene concentration and included 8.5% polyethylene glycol (PEG) to stabilize these organelles (1).In this study, liver and heart isolated mitochondria and hepatoma type cells (HTC cells) in PEG were treated with either 2% or 0.1% toluene, respectively. The HTC cells were in a solution of 10% PEG, the optimal concentration indicated by biochemical data. The mitochondria were fixed in suspension in 3% glutaraldehyde in 0.1 M phosphate buffer (pH 7.3). It was necessary to add 50% gl utaral dehyde to the HTC cells in PEG-buffer to give a final 3% concentration in order to prevent gross morphological degradation determined to be a result of aqueous glutaraldehyde fixation. Following treatment, specimens were post-fixed in 1% OsO4 and prepared for electron microscopy (1,2).
Morphology, Histochemistry and Staining of Glycogen in the Dog Heart
Authors: Rybicka Krystyna 
Published: June 2020

Muscle glycogen appears in the form of single beta-granules which become visible after staining with lead. Treatment of tissue with uranyl acetate before dehydration (en bloc) causes an apparent disappearance of glycogen. However, histochemical studies have shown that at least a part of glycogen remains in the tissue (5). In our work on the conducting tissue in the dog heart various degrees of glycogen disappearance were observed after uranyl acetate treatment of the tissue (3). The present report includes ultrahisto- chemical analysis of those samples that showed a high degree of glycogen disappearance and a tentative explanation of the effects of uranyl acetate on glycogen structure and staining.Dog heart was fixed by perfusioninvivo with 3% glutaraldehyde in 0.1 M phosphate buffer, pH 7.2. Excised conducting fibers were fixed overnight in 6% glutaraldehyde, post fixed in OsO4, for 15 minutes, processed either routinely or with uranyl acetate, and embedded in Spurr's epoxy resin.
Analysis of Collagen Fibril Diameters from Rabbit Corneal Wounds
Authors: Cintron C. , Hassinger L.C. , Kublin C.L. 
Published: June 2020

The vertebrate cornea is an avascular, translucent organ composed of an orderly arrangement of tissues in three basically parallel layers: the
epithelium, stroma, and endothelium. The stroma, or substantia propia, is an avascular connective tissue containing a sparse population of cells and a tight interlacing meshwork of extracellular fibers. In the rabbit, the deep layers of the stroma contain sharply defined ribbons of fibers (lamellae) which interweave and cross each other at many different angles parallel to the surface of the cornea. The fibers are composed of numerous fibrils which travel in the same direction within the given fiber. These fibrils are made of collagen intimately associated with an apparently amorphous matrix.Current theory of corneal transparency suggests that restrictions in the cross-sectional diameter of collagen fibrils and the size of interfibrillar spaces are the main factors in maintaining corneal clarity. Corneal transparency is, therefore, determined in part by the physical and chemical nature of collagen in the organ.
Comparative Observations on Fatty Liver using Secondary and Back- Scattered Electrons
Authors: Nopanitaya Waykin , Grisham Joe W. 
Published: June 2020

The secondary electron (SE) mode in SEM is routinely used by biologists for the purpose of studying the surface features of biological specimens. This operational mode provides an image of cell and tissue components with greater depth of focus and higher resolution than that achieved by light microscopy. The SE mode of imaging, however, does not provide an insight into intracellular substructures and components of cells.With the advent of the modern SEM equipped with a back-scattered electron (BSE) detector, which is available in most current models, it is possible to detect intracellular fine structure in biological samples using the BSE imaging system. The present investigation is an attempt to demonstrate the usefulness of BSE imaging for detecting intracellular lipid droplets during accumulation in the liver and to compare these results with data obtained from the SE imaging system.
Effect of Calcitonin and Hydrocortisone on Skin Tumorigenesis in Mice
Authors: Lupulescu A. , Rogers J. , Herbert M. , Habowsky J. , Birmingham D. 
Published: June 2020

Skin tumorigenesis is a good experimental model for the study of cell division and differentiation. Previous reports using light microscopy showed that some hormones (hydrocortisone and epinephrine) can influence the DNA synthesis in the squamous epithelial cells. (1). Also, light and electron microscopic observations revealed that calcitonin and corticosteroids significantly intervene in collagen synthesis and fibroblast growth in wounded rabbit and rats on experimental carcinogenesis induced by topical application of 3-methylcholanthrene in mice.Adult Swiss mice were used in these experiments. They were divided in four groups of 6 mice each; A) Mice painted on dorsal skin with a 0.4% acetone solution of 3-methylcholanthrene (MCA), twice weekly for 2 months. B) Mice painted with MCA as above and concomitantly treated with salmon calcitonin (Calcimar), a dose of 5 MRCU (Medical Research Council Units) injected intramuscularly (im) twice weekly for 2 months. C) Mice painted with MCA and injected (im) with hydrocortisone acetate (Cortef) 2.5 mg.
Ultrastructural Features of a Poorly Differentiated Neoplasm Resembling Synovial Sarcoma
Authors: Simons P. K. 
Published: June 2020

Synovial sarcoma is a malignant mesenchymal tumor most commonly occurring in the extremities, but is occasionally seen in the trunk, head, and neck regions. The well developed lesion exhibits a distinct biphasic histologic morphology consisting of a spindle cell fibrosarcomatous stroma and epithelial-lined pseudoacinar structures with an associated mucopolysaccharide secretion. The presence of this biphasic pattern is dependent upon the degree of histologic differentiation. Few studies of the fine structure of synovial sarcomas are available and none of the literature has been concerned with these neoplasms occurring in the less common areas. The ultrastructural features of a tumor classified as a poorly differentiated synovial sarcoma are presented.A mass of irregularly shaped, cerebreform tissue was surgically removed from the left side of the neck of a 61 year old white male. The majority of the tissue was fixed in neutral buffered formalin and prepared for light microscopy.
Studies on the Reversible Effects of Concanavalin A on CHO Cells in Culture
Authors: McCarty Kenneth S. , Wallace N.R. , Kaufman B. , McCarty K.S. 
Published: June 2020

Plant lectins have been useful probes to test the concept that the plasma membrane plays an important role in the regulation of mitotic activity. The carbohydrate specificity of the proteins provides a means of identification of the residues available to the external environment of the cell surface as well as a capacity for the rapid reversal of its effect.As part of a series of studies on the post-synthetic modifications of chromosomal proteins during mitosis, we tested the effect of the lectin Concanaval- in A (ConA) on Chinese hamster ovary (CHO) cells (clone, K1, Pro-). The generation time for untreated cells was 11.9 hrs. Preliminary observations demonstrate that 30 μg/ml of ConA inhibits the cell cycle at a stage immediately prior to mitosis. The ConA treated cells assume a spherical configuration, which is maximal at the end of 10-11 hrs, with thymidine uptake evident at 4 hrs but not at 10 hrs.
Intercellular Junctions in Fanft-Induced Transitional Cell Carcinomas in Tissue Culture, In situ Freeze-Fracture Studies
Authors: Pauli Bendicht U. , Weinstein Ronald S. 
Published: June 2020

Junctional abnormalities have been described in electron microscopy studies of a broad spectrum of human and animal tumors (for review, see Ref. 1). In such studies, quantitative and qualitative descriptions have been related to tumor morphology and, occasionally, to tumor biological behavior. Few investigations have attempted to correlate changes in junction ultrastructure with dynamic aspects of malignant transformation since such studies would be difficult to carry out in solid tissues. Further, until recently, methods available for freeze-fracturing tissue cultures were cumbersome and limited in their applications.In this study, we have examined the ultrastructure of cell junctions in tissue culture lines derived from chemical carcinogen induced epithelial tumors, using a novel freeze-fracture technique. The ultrastructure of the cultures was contrasted with comparable solid tumors, as described elsewhere (2). We examined four cell lines in continuous culture (AY27, AY32, AY33, AY34), which we grew from FANFT-induced Fischer rat urinary bladder carcinomas (3), and a fifth line derived from subcutaneously transplanted rat bladder carcinoma (CN27T).
Fine Structure of Spermatogenesis in the Snail Tarebia Granifera (Melaniidae)
Authors: Scates Ronald W. , Blystone Robert V. 
Published: June 2020

Jacob (1), citing chromosomal studies, emphasized the extreme rarity, or possible non-existence of viable males in observed Indian populations of Melanoides tuberculatus, of the same family as Tarebia granifera. The snail population, almost totally female in chromosomal count, were presumed to reproduce parthenogenetically; no sexual reproduction was in evidence (no sperm were ever reported observed). Similar findings were reported by Pace (2) in his comprehensive study of populations of T. granifera on the island of Taiwan. Pace, correlating his own findings with those of Jacob, suggested that T. granifera reproduce by apomictic parthenogenesis.A population of T. granifera is found in Brackenridge Park, San Antonio, Texas. The reproductive tract of randomly selected snails was prepared for electron microscopy. The tissue was fixed in 3% glutaraldehyde in 0.1 M sodium phosphate buffer, postfixed in buffered 1% Osmium tetroxide, dehydrated, and embedded in Spurr embedding media.
The Armadillo Median Eminence: Correlative Scanning + Transmission Electron Microscopy and Cytochemistry
Authors: Ives Phillip J. 
Published: June 2020

The cerebral ventricular system, including the ependymal cells of the median eminence, is postulated to be an important site of neuroendocrine transport and control1. The median eminence helps to transfer activity between the hypothalamus and adenohypophyseal control centers. The ependymal lining of the 3rd ventricle contains many different cell types active in phagocytic or autoregulato^y mechanisms involving the transport of releasing hormone or biogenic amines2. Understanding the primitive mammalian ventricular system is essential in determining significance and comparison of structure, development and organization in the more advanced mammalian species. The present investigation was designed to study the organization of the armadillo median eminence and allow for comparison with other animal systems.The median eminence was removed from each of four immature and eight adult male and female armadillos and processed using standard EM techniques. Some samples were scanned and then placed in 100% acetone and processed for correlative TEM.