bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microchemical Analysis in the HB5 STEM
Authors: Houghton D.C. 
Published: June 2020

The microchemical analysis of small extracted precipitates well dispersed on thin carbon support films has been carried out in a vacuum generators HB5 STEM, Particles in the size range ∼ 2 nm to several microns have been analyzed by a combination of simultaneous EDX and microdiffraction techniques. The major significance of this precipitate characterization is the high spatial resolution ∼ 5 nm and low detectability limit 5.10-20 g demonstrated by the EDX technique. However, a disturbing and frequently recurring feature of precipitate microanalysis was the detection of steep concentration gradients even within ∼ 10 nm precipitates.The McMaster HB5 is equipped with a virtual objective aperture, a modified x-ray collimator(1) and a double tilt berylium specimen holder, which minimize continuum and instrumental contributions to EDX spectra and have allowed high precision microchemical analysis. EDX data was obtained from a region of interest by first imaging at 25.106 to attain thermal stability, then stopping the probe and simultaneously monitoring the microdiffraction pattern during EDX acquisition.
Microstructure and Chemistry of Grain Boundaries in Sensitized Low-Carbon High-Nitrogen Type 316 Stainless Steel
Authors: Hall E. L. 
Published: June 2020

The resistance of stainless steel to sensitization can be increased by reducing the carbon content, since sensitization is caused by the formation of chromium-rich carbides at grain boundaries which depletes the boundary region of chromium. The reduction in carbon content also lowers the strength of the steel, but this can be counteracted by adding nitrogen, leading to a series of low-carbon high-nitrogen alloys which are promising candidates for applications in the nuclear industry. However, the effect of nitrogen on the phase relationships in stainless steel are complex, and the purpose of this study is to examine these effects.Samples of 316 stainless steel with 16 w/o Cr, 9.8 w/o Ni, 2.5 w/o Mo, 0.03 w/o C, and 0.06-0.16 w/o N which had been solutionized and then aged at 600-700°C for 3-300 hours were used. Grain boundary phases were identified using electron diffraction, and grain boundary chemistry was measured using X-ray spectroscopy with a 10nm probe, either positioned directly on the boundary or stepped across the boundary with a spatial resolution of 50nm. The Cliff-Lorimer method was used to quantify the x-ray results.
TEM Observations of Dislocation Emission at Grain Boundaries in Response to Uniaxial (Tensile) Straining
Authors: Murr L.E. 
Published: June 2020

Although it now seems to be generally recognized that grain boundaries and other interfaces are sources for dislocations, there are only scant few observations which tend to show convincing evidence for this. Murr earlier suggested that dislocation pile-ups in deformed metals and alloys (especially of low stacking-fault free energy) were primarily dislocation emission profiles, and more recent quantitative studies tend to unambiguously confirm this for uniaxial tensile deformation. Some of these features are illustrated in Fig. 1(a) and (b) which show a systematic increase in the number of dislocation profiles associated with grain boundary ledges at increasing tensile strains; observed in a Hitachi H.U. 200 F transmission electron microscope.The results shown in Fig. 1(a) and (b) were obtained as part of a systematic study of dislocation emission following the straining of 304 stainless steel sheet samples in separate, conventional tensile tests. Consequently these observations, while qualitatively and even quantitatively convincing, lack the force of direct, in-situ observations.
Microstructure and Magnetic Domain Wall Motion
Authors: Lin I. N. 
Published: June 2020

MnZn-ferrites and Li-ferrites are soft magnetic materials used in telecommunication and entertainment electronics because of their high magnetic permeability and low magnetic loss characteristics. The magnetic properties of these materials are very sensitive to composition and microstructure. In the present paper, results of an investigation of the interaction of magnetic domains with the microstructural features are presented and the significance of such studied on microstructure-property relationships is discussed.Lorentz microscopic technique in TEM has been used to study the domain wal structure and its interaction with grain boundaries, precipitates, pores, cracks, etc. in situ. Electron transparent specimens from bulk samples were prepared by ion beam milling technique and were examined in a Philips EM301 microscope operating at 100kV. The motion of domain walls was studied in situ by tilting the specimen so that there is a magnetic field applied to the plane of the specimen.
Transmitted Electron Detector and Grid Holder for a JEOL-U3 SEM
Authors: Smucker R. A. , Taylor M. E. 
Published: June 2020

Energy dispersive x-ray microanalysis has become widely used as a supportive technique in studies of biological tissues. Installation and use of the x-ray detector in many instruments such as the JEOL-U3 S.E.M. is a relatively simple task. Microanalysis of bulk specimens is likewise relatively easy to accomplish in the JEOL-U3 S.E.M. However, in order to perform microanalysis on single cells or small areas within a tissue it is desirable to examine thin sections of embedded or cryo-sectioned cells and tissues. Until the present, there hasn't been a transmission electron detector available for the JEOL-U3 except for an expensive unit available from JEOL.A prototype transmission electron detector was obtained for less than $1,000.00. The detector (Fig. 1) was constructed of a quartz light pipe and epoxied to an aluminum base which was mounted, in place of the normal secondary electron detector. A detector was made by forming an optical grade quartz rod to the appropriate geometry. The detection end and the PMT side were ground and polished as needed.
Alkaline Dissociation Products ofLumbricus TerrestrisHemoglobin Viewed with the STEM
Authors: Kapp O. H. , Ohtsuki M. , Robin N. , Vinogradov S. N. , Crewe A. V. 
Published: June 2020

Annelid extracellular hemoglobins are among the largest known proteins (M.W = 3.9 x 106), and together with the hemocyanins are the largest known oxygen carriers. They display oxygen affinities generally higher than those o vertebrate hemoglobins with Hill coefficients ranging from slightly higher than unity to values as high as 5-6. These complex molecules are composed of multiple copies of as many as six different polypeptides and posse: approximately 150 hemes per molecule.The samples were diluted to 100-200 μg/ml with distilled water just before application to a thin carbon film (∽15 Å thick). One percent (w/v) uranyl acetate solution was used for negative staining for 2 minutes and dried in air. The specimens were examined with the high resolution STEM. Their general appearance is that of a hexagonal bilayer (Fig. 1), each layer consisting of six spheroidal subunits. The corner to corner hexagonal dimensic is approximately 300 Å and the bilayer thickness approximately 200 Å.
SSB Protein—Its Interaction with DNA and Use as a Tool in Studying Genome Structure
Authors: Chrysegelos Susan , Dunn Kathi , Griffith Jack , Manning Marcia , Moore Claire 
Published: June 2020

A protein which binds tightly to single stranded DNA but not duplex DNA was first isolated from Escherichia coli (E. coli) by Sigal et. al and is called SSB for single stranded DNA binding protein. Together with SSB the gene 32 protein of T4 infected E. coli cells, and the gene 5 protein of phage M13 infected cells, are the best characterized members of the helix destabilizing family of proteins. They all share the properties (reviewed by Kbrnberg) of binding very tightly and cooperatively to single stranded DNA, of binding somewhat less well to single stranded RNA, and of binding poorly if at all to duplex DNA or RNA. In binding single stranded polynucleotides these proteins disrupt all secondary structure yielding a linear nucleoprotein complex. The details of binding however are very different from one protein to another and must reflect their functional roles in vivo.Physical studies of SSB have showi it to exist as a 75,000 dalton tetramer in solution which is assumed to be the active unit.
A Quantitative Ultrastructural Study of Peripheral Blood Lymphocytes Containing Parallel Tubular Arrays in Epstein-Barr Virus and Cytomegalo-Virus Mononucleosis
Authors: Payne C. M. , Tennican P. M. 
Published: June 2020

In the normal peripheral circulation there exists a sub-population of lymphocytes which is ultrastructurally distinct. This lymphocyte is identified under the electron microscope by the presence of cytoplasmic microtubular-like inclusions called parallel tubular arrays (PTA) (Figure 1), and contains Fc-receptors for cytophilic antibody. In this study, lymphocytes containing PTA (PTA-lymphocytes) were quantitated from serial peripheral blood specimens obtained from two patients with Epstein -Barr Virus mononucleosis and two patients with cytomegalovirus mononucleosis. This data was then correlated with the clinical state of the patient.It was determined that both the percentage and absolute number of PTA- lymphocytes was highest during the acute phase of the illness. In follow-up specimens, three of the four patients' absolute lymphocyte count fell to within normal limits before the absolute PTA-lymphocyte count.In one patient who was followed for almost a year, the absolute PTA- lymphocyte count was consistently elevated (Figure 2). The estimation of absolute PTA-lymphocyte counts was determined to be valid after a morphometric analysis of the cellular areas occupied by PTA during the acute and convalescent phases of the disease revealed no statistical differences.
Dupuytren's Contracture and Microvessels
Authors: Klscher C. W. , Speer D. 
Published: June 2020

Dupuytren's Contracture is a nodular proliferation of the longitudinal fiber bundles of palmar fascia with its attendant contraction. The factors attributed to its etiology have included trauma, diabetes, alcoholism, arthritis, and auto-immune disease. The tissue has been observed by electron microscopy and found to contain myofibroblasts.Dupuytren's Contracture constitutes a scar, and as such, excessive collagen can be observed, along with an active form of fibroblast.Previous studies of the hypertrophic scar have led us to propose that integral in the initiation and sustenance of scar tissue is a profusion of microvascular regeneration, much of which becomes and remains occluded producing a hypoxia which stimulates fibroblast synthesis. Thus, when considering a study of Dupuytren's Contracture, we predicted finding occluded microvessels at or near the fascial scarring focus.Three cases of Dupuytren's Contracture yielded similar specimens, which were fixed in Karnovskys fluid for 2 to 20 days. Upon removal of the contracture bands care was taken to include the contiguous fatty and areolar tissue which contain the vascular supply and to identify the junctional area between old and new fascia.
Control of Transcription of tRNA Genes
Authors: Sprague K.U. , Morton D. , Larson D. 
Published: June 2020

Our laboratory is interested in the regulation of gene expression during eukaryotic development. Among the genes we are currently studying are those coding for alanine tRNA in the silkworm, Bombyx mori. These genes are particularly interesting because one Bombyx alanine tRNA species is constitutive -- that is, it is found in a variety of cell types -- while the other major alanine tRNA appears only in the silkgland. The silkgland-specific tRNA predominates when the highly specialized cells of this tissue are synthesizing large amounts of the alanine-rich silk protein, fibroin. The nucleotide sequences of the two alanine tRNAs indicates that they are encoded by different genes.Our goal is to understand the molecular mechanisms governing the differential expression of Bombyx tRNAAla genes. Our approach is to isolate the genes with molecular cloning techniques, and to transcribe and process them in vitro. We have cloned 14 different genomic DNA fragments containing tRNAAla genes, and have developed faithful transcription systems from several different Bombyx tissues, including silkgland.
Prenatal Development of Muscle Spindles in the Mouse
Authors: Kozeka Kenneth 
Published: June 2020

A closely spaced, serial, light and electron microscopic technique has permitted determination of the patterns of distribution, three dimensional cytoarchitecture and ultrastructural characteristics of developing muscle spindles in the fetal mouse extensor digitorum longus muscle (Figs. 1-6).Spindle development begins at 15 daysin utero, when unmyelinated afferent nerves contact large, primary myotubes, located at the muscle's neurovascular hilum. By 17 daysin uterothe adult number of spindles containing one or two myotubes, can be identified in serial ultrathin sections through the myotube's sensory innervated region. While the primitive capsule of the spindle surrounds the intrafusal myotubes, it is initially confined to the sensory area and does not extend the length of the myotube. At this stage the peripheral regions of the intrafusal myotubes are morphologically indistinguishable from neighboring extrafusal myotubes.It is in this peripheral region that fusimotor innervation will develop.By following the spindles in serial, spaced (i.e., 15μm intervals), ultrathin transverse sections along their length, it is possible to establish the continuity of the sensory innervated region with the peripheral regions of the intrafusal myotube and to determine that fusimotor innervation is not present at 17 daysin utero.
Effect of Streptozotocin-Induced Diabetes on Estradiol-Stimulated Changes in the Ultrastructure of the Rat Endometrium
Authors: Frederick G.T. , Gardner R.M. , Kirkland J.M. , Stancel G.M. 
Published: June 2020

Estradiol (E2)-stimulated uterine growth has been well characterized both biochemically and morphologically. Recent studies have shown that insulin plays an important role in the regulation of cellular development. This study examines the effect of streptozotocin-induced diabetes on E2-stimulated changes in the ultrastructure of the endometrium of the rat uterus.Sprague-Dawley rats were ovariectomized at 21 days of age. Diabetes, defined as blood glucose levels greater than 300mg%, was induced in half of these animals by the injection of 85mg streptozotocin/kg body weight.The remaining animals were classified as normal. Animals from both groups were injected with either 0.9% saline or 4μg E2/100gm body weight. At 18, 24, 36 and 48 hours post-injection of E2, uterine segments were collected from 8-10 animals in each experimental group and processed for electron microscopic examination. Uterine segments from saline-injected animals served as controls. Data summarized describe observations made from thin-sections and have not been extrapolated for whole cells.
The Response of Testis Cells to Low Dose X-Irradiation
Authors: E. Philpott D. , Sapp W. , Williams C. , Stevenson Joann , Black S. 
Published: June 2020

The response of spermatogonial cells to X-irradiation is well documented. It has been shown that there is a radiation resistent stem cell (As) which, after irradiation, replenishes the seminiferous epithelium. Most investigations in this area have dealt with radiation dosages of 100R or more. This study was undertaken to observe cellular responses at doses less than 100R of X-irradiation utilizing a system in which the tissue can be used for light and electron microscopy.Brown B6D2F1 mice aged 16 weeks were exposed to X-irradiation (225KeV; 15mA; filter 0.35 Cu; 50-60 R/min). Four mice were irradiated at each dose level between 1 and 100 rads. Testes were removed 3 days post-irradiation, fixed, and embedded. Sections were cut at 2 microns for light microscopy. After staining, surviving spermatogonia were identified and counted in tubule cross sections. The surviving fraction of spermatogonia compared to control, S/S0, was plotted against dose to give the curve shown in Fig. 1.
The Grid-All: A Multiple Grid Handling, Staining, and Storage Device for Use in Electron Microscopy
Authors: Giammara Beverly 
Published: June 2020

A number of methods, including those reviewed by Hayat, have been devised for holding and staining groups of grids. The Grid-All (Polysciences, Inc.), however, has additional functions, including the collection of grids serially from the ultramicrotome, transport, staining, washing and storage, all in the same module (Fig. 1). The grids are kept securely locked and serially held by the Grid-All through all the procedures to which grids are subjected. Grid-Alls have been made in different sizes to hold groups of 3,5,10 or 15 grids. The largest 15-slot Grid-All can be cut to make smaller units, if desired.The Grid-All is made of a flexible RTV Silastic material that allows insertion of any kind of grid, including tabbed or slotted, when it is flexed (Fig. 2). When relaxed, the material grips the grids tightly in its slots. Protective posts prevent mechanical damage to the grids being held, even if the holder is dropped.
Sachharide Staining in Thin Sections
Authors: Marenus K. , Kuhn E. , Beer M. 
Published: June 2020

A specific reagent for the glycol groups of sugars yields similar staining patterns in isolated or embedded and thin sectioned rat tail tendon. These results suggest that the stain specificity and the structure of the protein fibers are retained after cross linking, embedding and thin sectioning.Osmate in the presence of tetramethylethylenediamine (TEMED) binds to glycols and has been found to stain sugar residues. SLS aggregates, in which adjacent molecules lie in exact register, can be formed by addition of ATP to collagen monomers. Osmate-TEMED staining of these has produced a specific band in Type I collagen at a known glycol position 10% along the molecule from the N-terminal end. We have observed a second band 10% from the C-terminal end (Fig. 1) which is also faintly visible in. In addition, other weak bands have been observed.
Hingeless Complementary Specimen Holders for the Denton Freeze-Etch Apparatus
Authors: Steere Russell L. , Erbe Eric F. 
Published: June 2020

A major complication in the use of complementary specimen holders in the Denton freeze-etch apparatus has been breakage of the holders due to the freezing of specimen liquid within the hinges. The hinged holders (Steere and Moseley, 1970) were designed with gaps to prevent capillary movement of specimen liquid into the hinge. Nevertheless, some holders were manufactured with insufficient gaps and many operators fail to take sufficient precautions in sample loading which results in the breakage of specimen holder hinges.In order to avoid such problems, we have developed a new specimen cap and new complementary specimen holders without hinges (Fig. 1). Because of the simple design of the holders, they can be cut out by hand or by use of a specially designed punch. They can be made in different widths and out of various metals or plastics. Specimen slots of any desired size or orientation can be cut into the opposing faces of the complementary halves of specimen holders.
A Comparison of the Ultrastructural Morphology of Hepatic Necrosis in BDF1 Mice
Authors: Jackson Becky 
Published: June 2020

Preliminary investigation has indicated similarity in hepatic ultrastructural morphology in nutritional deprivation, and cyanide induced hepatic necrosis. Analysis of hepatic tissue has indicated disruption of intracellular membranes, specifically, reduction in rough endoplasmic reticulum (RER) mitochondrial integrity, and glycogen stores. An increase in smooth endoplasmic reticulum (SER) portion was observed.To further investigate the apparent equivalence of necrotic morphology, ultrastructura1ly, BDF1 mice were subjected to senescence, nutritional deprevation, potassium cyanide (KCN) induced toxemia, and acetaminophen induced toxemia. Controls were utilized to ellucidate non-necrotic hepatocellular normals. U1trastructura1 investigation of controls (Fig. 1) shows densely granular RER, abundant glycogen stores, and morphologically normal mitochondria. Subjects with acetaminophen induced necrosis exhibit reduced normal RER with increased levels of dialated, vesicular RER in apparent conversion to SER (Fig. 2), loss of mitochondrial integrity, and glycogen store reduction. Senescent subjects exhibit a pronounced increase in SER and loss of glycogen store. (Fig. 3). Investigation of the senescent SER at high magnification (Fig. 5) indicates that the SER is arising from degranulating and vesiculating RER.
Method for the Ultrastructural Evaluation of Rodent Nasal Mucosa
Authors: Popp James A. , Martin Joseph T. 
Published: June 2020

In recent years extensive ultrastructural studies of the pulmonary system have been published. Many of these studies have been initiated to clarify the effects of air pollutants and inhaled gases on tracheal mucosa, intrapulmonary air passages and alveoli. Although light microscopic evaluation of the nasal mucosa has been included in some recent morphologic studies of the effects of inhaled toxicants, the ultrastructural effects on nasal mucosa have rarely been published. This lack of information is primarily due to the difficulty of preparing the epithelial mucosa for examination since it is completely encased in bone. We have developed a detailed systematic method to prepare any site in the rat nasal mucosa for ultrastructural evaluation by both transmission and scanning electron microscopy.Fixation is achieved by an intravascular perfusion technique using meto- fane (Pitman Moore, Inc.) anesthetized 200 gram Fischer-344 rats. The perfusing catheter is inserted through the left ventricle and into the ascending aorta.
A Preliminary Study of Thin Bird Disease
Authors: Davis Ronald W. , Kenzy Samual , Stauber Erik H. 
Published: June 2020

We have initiated a study of a disease that is usually fatal to domestic parakeets and canaries. We have called this syndrome “thin bird disease” for lack of a better name.Clinically, the disease is diagnosed after observing a bird that is thin, exhibits severe weight loss, lethargy, and ruffled feathers. Fecal smears of affected birds contain many very large, single-celled, rod-shaped bacteria measuring up to 1μm x 90μm.Post mortem examination of birds exhibiting external symptoms of the disease reveals an enlarged ventriculus (gizzard) that contains unmacerated seeds. A jelly-like mass is found in the ventriculus and pro-ventriculus of affected birds. This material contains bacteria morphologically identical to those found in fecal smears (Figs. 3, 4).Samples of ventriculus and pro-ventriculus from birds clinically diagnosed as diseased and normal were collected and processed for light microscopy, scanning and transmission electron microscopy. The specimens were fixed in half strength Karnovsky's fixative, post fixed in OsO4, and either embedded in plastic or critical point dried.