bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure in pituitary gonadotrophs and Leydig cells of sterile male mice
Authors: Andrews Annette M. , Hoage Terrell R. , Turner Jack , Bishop Jack B. 
Published: June 2020

Mouse systems are used as models to test for chromosome translocations and other damage caused by exposure to environmental chemicals. To evaluate mutagenic activity of triethylenemelamine (TEM), 397 male offspring with chromosome translocations were produced from TEM-treated CD1males and F1(C57BL/6J x BALB/c) females. Breeding tests showed 26 to be sterile but cytogenetic examination by hemiorchiectomy at 11-13 months was inconclusive because of reduced meiotic activity. Radioimmunoassay for serum testosterone showed a range from 0.96 ± 0.41ng/ml to 10.55 ± 1.65ng/ml in sterile males while fertile translocation and control animals showed 3.17 ± 0.53 ng/ml. This study used 2-3 animals per group, selected from a non-treated control group and from groups with high serum testosterone (HT), medial serum testosterone (MT) and low serum testosterone (LT).Pituitary and testes were removed from ether-anesthetized animals, immediately fixed in 4% gl utaraldehyde, post-fixed in 1% OsO4, dehydrated in ethanol, and embedded in Epon-araldite resin. Thin sections (l00nm) were stained with uranyl acetate and lead citrate then examined at 60kV in a Philips 201 electron microscope.
Emigration of neutrophils in the central nervous system
Authors: L.Beggs John , Waggener John D. , Miller Wanda , Watkins Jane 
Published: June 2020

Studies using mesenteric and ear chamber preparations have shown that interendothelial junctions provide the route for neutrophil emigration during inflammation. The term emigration refers to the passage of white blood cells across the endothelium from the vascular lumen. Although the precise pathway of transendo- thelial emigration in the central nervous system (CNS) has not been resolved, the presence of different physiological and morphological (tight junctions) properties of CNS endothelium may dictate alternate emigration pathways.To study neutrophil emigration in the CNS, we induced meningitis in guinea pigs by intracisternal injection of E. coli bacteria.In this model, leptomeningeal inflammation is well developed by 3 hr. After 3 1/2 hr, animals were sacrificed by arterial perfusion with 3% phosphate buffered glutaraldehyde. Tissues from brain and spinal cord were post-fixed in 1% osmium tetroxide, dehydrated in alcohols and propylene oxide, and embedded in Epon. Thin serial sections were cut with diamond knives and examined in a Philips 300 electron microscope.
Dissolution of eosinophil granules in bronchial lavage obtained from allergic asthmatics during bronchoprovocation and seasonal exposure
Authors: Worden K. A. , Metzger W. J. , Kopp W. , Richerson H. B. , Hunninghake G. 
Published: June 2020

Bronchial lavage was used to assess changes in cell populations from the airways of allergic asthmatic patients who were exposed seasonally to allergens or challenged with aerosolized allergen. Bronchoprovocation (BPC) was used to elicit early and late asthmatic responses (LAR), and bronchial lavage was performed at baseline out of season or at either 2, 6, or 24 hours after challenge, and during the season in five mildly symptomatic patients. Four normal subjects were challenged with allergen and lavaged either 2 or 6 hours later.Bronchial lavage fluid and cells from subsegmental bronchi were immediately passed through 2 layers of gauze and cells were washed once with Hank's buffered salt solution and gently centrifuged. Cyto-preps of lavage cells were prepared and examined by light, microscopy with a Wright-Giemsa stain. These cells were then mixed with 50% Percoll and centrifuged at 1500 RPM for 20 minutes. This procedure was adopted to concentrate small numbers of cells such as eosinophils and mast cells into a pellet which contained relatively few macrophages.
Solute Segregation in Stainless Steel under Irradiation
Authors: Kenik Edward A. 
Published: June 2020

Solute element additions can significantly influence the behavior of an alloy under irradiation. The aggregation of irradiation-induced vacancies into three-dimensional clusters, voids, and the volume expansion, swelling, associated with void formation is of prime concern in the design of nuclear reactors. A modified type 316 stainless steel, LS1A, has been developed which exhibits high resistance to swelling. This alloy, containing ˜1.0 wt % silicon and 0. 15 wt % titanium, swells 30 times less under nickel ion irradiation than a nominal type 316 stainless steel.In addition to the observation of swelling resistance in LS1A, it was observed that the evolution of dislocation portions of the damage structure was modified by the silicon and titanium additions. Specifically, the stability of faulted dislocation loops in LS1A is quite high and the growth of large loops is severely curtailed. At higher doses, radiation-induced precipitates of the same size and shape as the dislocation loops were observed.
The Use of a Lanthanum Hexaboride Filament in a Transmission Electron Microscope - The Philips EM-400
Authors: Mumaw V. R. , Munger B. L. 
Published: June 2020

The use of lanthanum hexaboride (LaBg) as an electron source in scanning electron microscopes equipped with an ion pumped emission chamber at less than 10~6 torr, has proven to be very advantageous. It was not until the introduction of the Philips EM-400 that a standard commercially available transmission electron microscope was differentially pumped between the emission chamber and the viewing chamber and capable of achieving a vacuum suitable for utilizing this type of electron source.Only minor modifications were necessary to use the LaBg filament (Kimbal Physics, Wilton, N.H.) in the Philips EM-400 electron microscope. The Wehnelt cap was modified so that the Wehnelt aperture can be removed without disassembly of the cap (Fig. 1). The Wehnelt aperture is 0.7 mm in diameter. A simple spanner wrench is used to remove the Wehnelt aperture. Rough centering of the filament was quite easy using a Zeiss operating stereomicroscope at 25X with the Wehnelt aperture removed.
Observation of Atom Rows in Thorium Pyromellitate Using a Field Emission STEM
Authors: Todokoro H. , Nomura S. , Komoda T. 
Published: June 2020

It is interesting to observe polymers at atomic size resolution. Some works have been reported for thorium pyromellitate by using a STEM (1), or a CTEM (2,3). The results showed that this polymer forms a chain in which thorium atoms are arranged. However, the distance between adjacent thorium atoms varies over a wide range (0.4-1.3nm) according to the different authors.The present authors have also observed thorium pyromellitate specimens by means of a field emission STEM, described in reference 4. The specimen was prepared by placing a drop of thorium pyromellitate in 10-3CH3OH solution onto an amorphous carbon film about 2nm thick. The dark field image is shown in Fig. 1A. Thorium atoms are clearly observed as regular atom rows having a spacing of 0.85nm. This lattice gradually deteriorated by successive observations. The image changed to granular structures, as shown in Fig. 1B, which was taken after four scanning frames.
An Electron Microscope for High Quality Low Magnification with a Wide Field
Authors: Kubozoe M. , Sato H. , Kasai S. , Ozasa S. 
Published: June 2020

A permanent magnet which is a combination of cobalt and some rare earth metal is recently being utilized. HICOREX is a commercial product of this magnet. Its maximum BH is several times larger than that of an ordinary Alnico magnet, providing a value of 10 n* 26 MGOe. When this permanent magnet is used for an electron lens (called HICOREX lens), not only does it offer a very strong lens but it can be made extremely small, and a new facility can be devised using this feature.A triple pole piece lens which is made by combining two HICOREX magnets enables relatively easy compensation of magnification distortion and spiral distortion, and its effective radius of field is about twice that of an ordinary lens excited with an electromagnetic coil. This HICOREX lens has a diameter of 16 mm and height of about 10 mm. Despite being so tiny its focal length is about 3 mm at 75 kV accelerating voltage (refer to Fig. 2).
Measurement of the Displacement Across a Coincidence Grain Boundary
Authors: Matthews J. W. , Stobbs W. M. 
Published: June 2020

Many high-angle grain boundaries in cubic crystals are thought to be either coincidence boundaries (1) or coincidence boundaries to which grain boundary dislocations have been added (1,2). Calculations of the arrangement of atoms inside coincidence boundaries suggest that the coincidence lattice will usually not be continuous across a coincidence boundary (3). There will usually be a rigid displacement of the lattice on one side of the boundary relative to that on the other. This displacement gives rise to a stacking fault in the coincidence lattice.Recently, Pond (4) and Smith (5) have measured the lattice displacement at coincidence boundaries in aluminum. We have developed (6) an alternative to the measuring technique used by them, and have used it to find two of the three components of the displacement at {112} lateral twin boundaries in gold. This paper describes our method and presents a brief account of the results we have obtained.
Metallurgical Effects of Grain Boundary Ledges
Authors: Murr L.E. 
Published: June 2020

Ledges in grain boundaries can be identified by their characteristic contrast features (straight, black-white lines) distinct from those of lattice dislocations, for example1,2[see Fig. 1(a) and (b)]. Simple contrast rules as pointed out by Murr and Venkatesh2, can be established so that ledges may be recognized with come confidence, and the number of ledges per unit length of grain boundary (referred to as the ledge density, m) measured by direct observations in the transmission electron microscope. Such measurements can then give rise to quantitative data which can be used to provide evidence for the influence of ledges on the physical and mechanical properties of materials.It has been shown that ledge density can be systematically altered in some metals by thermo-mechanical treatment3,4.
Microscopical Detection Of Fiber-Finish Interaction Sites
Authors: Goynes W. R. , Carra J. H. , Timpa J. D. 
Published: June 2020

In the chemical finishing of textile products, final location of the chemical agent is affected by several factors. Finish location can be critical to production of a desired effect, especially when more than one finish is used on a fabric blended of different fibers. To predetermine location sites, it is first necessary to be able to detect areas of chemical interaction and to determine under what conditions a given location is attained. Microscopical methods show the presence of chemical finishing agents in various sites of the morphological structure of a fabric.Tetramethylol 2,4-diamino-6(3,3,3-tribromopropyl)triazine (TM-DABT) is an effective, durable flame retardant for all-cotton fabrics. Solubility studies of cross sections from TM-DABT-finished cotton fibers indicated that the chemical had penetrated the fiber and insolubilized it to the cellulose solvent cupriethylenediamine hydroxide (cuene).
Quantitative Stereology and Image Analysis
Authors: Underwood Ervin E. 
Published: June 2020

Stereology is the study of the three-dimensional structure of materials from two-dimensional sections or projections. By suitable statistical measurements on the test plane or projection plane, and by utilizing the basic equations of stereology, the true three-dimensional quantities can be calculated. Such attributes of the structure as points P, lines L, surfaces S, volumes V, numbers N, as well as spacings, sizes, curvatures, etc. can be obtained without a priori assumptions.In this review, the basic relationships of quantitative stereology are summarized, both for opaque and transparent materials. Thus the image to be analyzed may derive from a photograph of a metallic polished surface or from an electron transmission micrograph obtained from a biological slice or replica. The complete quantitative characterization of the microstructure involves data obtained from both reflected images and transmitted (or projected) images. We will discuss the relationships applicable to each type of image, then show their interrelationships.
The Uses of Electron Energy Loss Spectrometry in Biology
Authors: Johnson D. E. 
Published: June 2020

The uses of electron energy loss spectrometry in biological microscopy range from the simple filtering of energy loss electrons to remove their degrading effect in conventional transmission microscopes, to the detailed use of the information carried by energy loss electrons in determining molecular and elemental composition on a microscopic level. The electron energy loss spectrum, to the extent that it is characteristic of the specimen, reflects the atomic and molecular energy levels of the specimen. In considering the uses of electron energy loss spectrometry in biology it is convenient to separate the energy loss events into two groups, those characteristic of the molecules present and those characteristic of the elements present.The energy loss spectrum of organic materials in the region below ∽10ev energy loss reflects the same molecular transitions as ultraviolet and vacuum ultraviolet absorption spectra in this energy region and is equally characteristic of the molecules present.In the region from ∽10ev to 50ev are energy loss events resulting from additional single electron excitations and ionizations modified by collective effects in the solid.
Cross-Sections for K-Shell Excitation by Fast Electrons
Authors: Egerton R. F. , Joy D. C. 
Published: June 2020

The cross-section for excitation of an electron from the innermost shell of a given atom can be determined directly by measuring the proportion of fast incident electrons which have suffered an appropriate energy loss, or (if the X-ray or Auger yields are known) from the number of X-ray quanta or Auger electrons emitted as a result of de-excitation.In the direct method, this cross-section is obtained as a function of α, the maximum scattering angle allowed into the detector, and for a thin specimen it is given by:where n is the number of atoms per unit volume of specimen, t is the specimen thickness, Ik(α) represents the number of K-loss electrons reaching the detector and Itrepresents the total number of fast electrons entering the detector,1for the same value of α. Equation (1) can also be used12for microanalysis of low-atomic-number elements in order to measure n or nt if σK(α) is known.
Transmission Electron Microscopy Study of Precipitation in a Nickel-Beryllium Alloy
Authors: Hills C. R. , Nordstrom T. V. 
Published: June 2020

The aging sequence in precipitation hardening Ni-2 w/o Be has been studied by transmission electron microscopy as a function of time at temperatures of 400°C, 565°C, 650°C and 750°C. The microstructural changes at different stages in the aging sequence were analyzed by a combination of electron diffraction and dark field microscopy. Prior to aging, the alloy was solution annealed at 1100°C for 6 hrs. Subsequent examination of the solution annealed material showed no evidence of either continuous or discontinuous precipitation.The precipitation sequence following aging at 400°C and 565 °C was found to be:This is analogous to that reported for the widely studied copper-beryllium1 and copper-zinc-beryllium2 systems. Precipitation commences with the nucleation of coherent platlet G. P. zones parallel to {001} matrix planes. As aging proceeds, the intermediate semicoherent γ precipitate is formed continuously from the G. P. zones.
TEM Specimen Preparation from Micro-Areas of Metallurgical Interest
Authors: Koch Edward F. 
Published: June 2020

Most metallurgical phenomena of industrial interest can trace their origin to specific regions in operating components. Determining the microstructural changes that accompany the origins of these metallurgical phenomena helps considerably in their overall understanding. Examples include studies of microstructural changes at crack tips, surface oxidation effects on base material, and narrow reaction zones in suitably heat treated material. For such microareas, only a single region of interest is usually available for microstructural examination, making TEM specimen preparation procedures extremely critical.304 austenitic steel is susceptible to intergranular stress corrosion cracking when subjected to a corrosive environment in the presence of stress and a sensitized microstructure. The latter is characterized by chromium carbide, Cr23C6, at the grain boundaries. Confirmation of the presence of these carbides at the tip of an intergranular crack created in an environment can be provided by TEM examination. The microarea of interest can be pinpointed by using selective platinum washers during electropolishing, yielding electron-transparent regions of the type shown in figure 1.
An Apparatus for Chemical Jet-Thinning
Authors: Russell Robert R. 
Published: June 2020

A simple, inexpensive and safe apparatus has been constructed to chemically jet-thin silicon samples for transmission electron microscopy. The thinning apparatus, constructed from chemically resistant materials, is designed to quickly and reproducibly thin samples without subjecting the operator to hazards from highly corrosive polishing solutions. Polishing action is accomplished from one side of the sample while the obverse surface is protected from attack, thus allowing TEM studies of very shallow-surface effects.Jet-thinning devices for producing electron transparent samples, particularly from silicon and germanium, have been previously reported (1, 2, 3, 4, 5). All of these devices accomplish essentially the same task. Most, however, have one or more of the following disadvantages: (a) they are cumbersome to use, requiring several steps of sample preparation prior to final thinning; (b) they are fairly complex mechanisms, expensive to construct, and often contain components susceptible to corrosion from polishing solutions, and (c) they are often hazardous to use, providing little protection to the user from highly caustic chemical polishes.
X-Ray Microanalysis of Enzyme Activity: Transport Atpase
Authors: Rosen S. , Beeuvkes R. 
Published: June 2020

Although electron prohe analysis is considered useful for detection of constituent elements in biological studies, only a few investigations, basically concerned with elemental identification, have been made to explore its potential in histoehemical studies of enzymes. The methods available for the cytochemical study of sodium-potassium activated adenosine triphosphatase (transport ATPase) all contain probe detectable elements, but a recent technique dependent on the closely associated K+ dependent-ouabain sensitive phosphatase activity provides appropriate circumstances for both detection and quantitation of enzyme reaction product (l). Because it measures the immediate product of enzyme hydrolysis, this method parallels conventional biochemical methods. The resolution of the probe allows activity to be determined at the cellular level.To perform probe analysis of enzyme activity in tissue sections, conditions must be found that result in the stabilization of enzyme product at the reaction site. For measurement of transport ATPase, the technique is based on the ouabain-sensitive, K-dependent phosphatase hydrolysis of p-nitrophenol phosphate in alkaline media containing dimethylsulfoxide.
Ultrastructural Localization of Cellulase in Diplodia Maydis and in D. Maydis-Infected Com Stalk Tissue
Authors: Murphy Judith A. , Thompson Mary R. , Pappelis A.J. 
Published: June 2020

BeMiller et.al.(l) found that D. maydis did not have the solubilizing enzyme C1. They reported that D- maydis exhibited cellulolytic activity constitutively, and hypothesized that the cellulolytic enzymes were attached to fungal hyphal surfaces because they found cellulase released to the culture medium only after the growth period, when available cellulose had been used up.The purpose of this study was to determine the location of cellulolytic enzymes (EC 3.2.1.4; beta-1,4-glucan glucanohydrolase) in D. maydis and D. maydis-infected corn tissue at the ultrastructural level.Cellulase activity produces glucose as an end product which will reduce cupric oxide and can be visualized with an EM because it is electron dense and the Cu component can be verified with x-ray analysis(Figs.l,2). After thorough washing, samples fixed in aldehydes are incubated in a substrate mixture at a low pH. The enzyme is activated and reducing sugar is released. The sample is then reacted with Benedict's solution at a high temperature, allowing CuO crystals to be deposited at the site of reaction.
Temperature Dependence of Beam Induced Mass Loss of Phenylalanine
Authors: Ramamurti K. 
Published: June 2020

We have previously reported the results of electron beam-induced mass loss of L-phenylalanine at 7°K (1,2). We are currently in the process of measuring the mass loss as a function of temperature.As reported earlier, we found negligible mass loss at 7°K. Reference 2 discussed in detail the precautions to be taken to ensure that the measurements are meaningful. In the current series of measurements, the specimen thickness is measured directly as a function of dose rather than measuring the thickness of an irradiated area relative to a reference area. This is done by recording the energy loss spectrum in the range 0-150 Volts with a multichannel analyzer. The number of unscattered and inelastically scattered electrons are found by summing over the respective regions in the spectrum.Corrections have been made to take into account 1) inclusion of a finite range of energy loss in the spectrum; 2) geometric collection efficiency of the aperture in the spectrometer; and 3) effects due to multiple scattering.
Ultra-Rapid Freezing of Isolated Skeletal Muscle Fibers
Authors: Sommer Joachim R. , Wallace Nancy R. 
Published: June 2020

After Howell (1) had shown that ruthenium red treatment of fixed frog skeletal muscle caused collapse of the intermediate cisternae of the sarcoplasmic reticulum (SR), forming a pentalaminate structure by obi iterating the SR lumen, we demonstrated that the phenomenon involves the entire SR including the nuclear envelope and that it also occurs after treatment with other cations, including calcium (2,3,4).From these observations we have formulated a hypothesis which states that intracellular calcium taken up by the SR at the end of contraction causes the M rete to collapse at a certain threshold concentration as the first step in a subsequent centrifugal zippering of the free SR toward the junctional SR (JSR). This would cause a) bulk transport of SR contents, such as calcium and granular material (4) into the JSR and, b) electrical isolation of the free SR from the JSR.
Quantitative Freeze Fracture Studies of Hepatoma Plasma Membranes
Authors: Stewart T.P. , Kowalak T.M. , Corwin S.P. , Hui S.W. 
Published: June 2020

The intramembranous particles (IMP's) seen in most freeze fractured membranes are generally regarded as “randomly” distributed in the plane of the membrane. In certain cases, the distributions of IMP's are apparently non-random. These nonrandom distributions have been described qualitatively as patching, aggregation or domain formation. These characteristics have been used to distinguish transformed cell membranes from their normal parental cells.1We attempted to quantitate the density and distribution of IMP's in the plasma membrane of (control) rat hepatocytes and in the plasma membranes of moderately slow-growing Reuber H-35 hepatomas. Because of the difficulty in obtaining a sufficiently large fractured surface area from the highly invaginated plasma membranes of these cells, the purified plasma membrane fraction was used for this study. The purified fraction2 consists mostly of right-side-out membrane vesicles.3 The purity of the membrane fraction was checked by thin section and marker enzyme assay.2