bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hot Stage HVEM Dynamic Studies of Order-Disorder Transitions in Lithium Ferrite
Authors: Van der Biest O. , Butler E. P. , Thomas G. 
Published: June 2020

Lithium ferrite (LiFe5O8) is a ferrimagnetic compound with some interesting technological properties. In the disordered state the compound has the spinel structure with a random mixture of lLi+and 3Fe3+on the octahedral sites (spacegroup Fd3m). Below 750°C the lithium ions and iron ions on the octahedral sites order and the spacegroup symmetry is lowered to P4332 (P4132). The resulting domain structure has been described in detail by Van der Biest and Thomas.The kinetics of the ordering reaction have been studied "in situ" in the hot stage of a HVEM. Annealing in the normal atmosphere of the microscope leads to a reduction of the compound in a way similar to that found for CoFe2O4. In order to control the stoichiometry of the compound during the ordering reaction, it is necessary to maintain an oxygen atmosphere around the specimen, hence the use of an "environmental" cell is necessary.
S.E.M. Fractography of Ultrasonic Fatigue in L65 Aluminum Alloy
Authors: Ashley K C H , Ditchfield R W , Downie G A McD 
Published: June 2020

An aluminium alloy (L65) was fatigue tested in a longitudinal tension compression mode at a frequency of 20 kHz with a mean strain of 1.65.10-3. The specimens used were simple cylinderical rods of fully hardened, solution heat treated or fully annealed aluminium alloy. The effects of the variation in heat treatment on the nature of fracture were investigated by examining the fracture surfaces of these specimens in a Cambridge S4-10 scanning electron microscope.The fracture surfaces of the fully hardened alloy exhibited the characteristics of cleavage fracture (Stage I and Stage II cracking) in agreement with Forsyth's theories. Occasionally these specimens underwent an unusual mode of centre initiated failure for which the fatigue endurance was greater than that experienced following the surface initiation in similar specimens.
Effect of Thermomechanical Treatment on the Grain Boundary Structure in Pure Aluminum
Authors: Venkatesh Eswarahalli , Murr L.E. 
Published: June 2020

In recent years, many researchers have shown great interest in understanding the structure of grain boundaries and their influence on the mechanical properties in metals and alloys. In recent years, the structure of grain boundaries and their control have been considered as a means of understanding the strengthening mechanisms in metals and alloys. There are many ways by which the grain boundary structure can be changed both in pure metals and alloys. One such means considered here is the thermomechanical treatment of pure metals.In the present work, high purity (99.9999%) aluminum sheet, mill rolled to 0.004 in. thick, is used. The as-received condition of the sample was flash-annealed at 903°K in an argon atmosphere. Batch specimens from this stock were cold rolled to 50% reduction in thickness and annealed in air at 903°K followed by either furnace cooling or air cooling to room temperature.
On the Contrast of High Resolution Backscattered Electron Images
Authors: Lin P. S. D. 
Published: June 2020

When the angle θ between the incident electron and the normal to a surface changes, the yield of secondary electrons Y varies approximately as secθ. The topographic contrast thus produced renders secondary electrons useful for surface studies. On the other hand, as the atomic number Z increases, the backscattering coefficient η increases more rapidly than Y. Therefore, backscattered electrons should be collected as signal when atomic number contrast is desired. Figs. 1 and 2 exemplify the increase of atomic number contrast as one switches from secondary to backscattered electron mode.Backscattering is not a localized process, since both single and plural/ multiple scattering are involved. In Everhart's model, incident electrons are retarded by the inelastic scattering and scattered backwards by large angle Rutherford scattering.
Detection of Reovirus-Like Particles in HeLa Cells
Authors: Holder Walter D. , Peer Gary W. 
Published: June 2020

The HeLa cervical carcinoma cell line was established in 1951 by George Gey at the Johns Hopkins Hospital in Baltimore, Maryland. HeLa cells have been subsequently used throughout the world in numerous laboratories. One of the subsequent cultures, designated the Hela D line has been found to contain virus morphologically and antigenically related to the Mason-Pfizer monkey virus (MPMV). The HeLa D line, containing virus, was originally derived from Dr. W.A.K. Schmidt in Dusseldorf, Germany.In the present study we examined HeLa D cells by transmission electron microscopy to morphologically evaluate the virus produced by this line. Cells were grown in RPMI-1640 medium with 10% v/v heat-inactivated fetal calf serum in a 5% C02/95% air incubator at 37° C. Cultures were fed twice weekly and submitted for electrormicroscopy when approximately 70% confluent 24 hours after feeding. Cells were scraped from the flasks, pelleted, fixed in 2.5% Millonig's buffered glutaraldehyde, post fixed in 1% osmium tetroxide and embedded in Epon.
Ultrastructural Variations in the Congenital Hair Defect Monilethrix
Authors: West H. 
Published: June 2020

The hair of Monilethrix is characterized by a noded appearance with the internode being very susceptible to breakage resulting in hair loss at the scalp. Freshly epilated hairs from a moderately affected male Caucasian having light brown hair were used.Histological examination of the bulb indicates the presence of vacuoles in the cortical prekeratinized area of the zone of cellular differentiation. Fig. 1 shows a morphological defect in the cells of the precortical region of the germinal matrix. The nuclei of several of these cells have become elongated and in some cases, string-like, with the nuclei becoming pyknotic. It is possible that the lack of a functioning nucleus early in cell growth results in large open areas or vacuoles. Gross structural analysis indicates that the internode region of the shaft has less cortical area than does the node.
Fine Structural Classification of Chromophobe Adenomas of the Human Pituitary Gland
Authors: Kovacs K. , Horvath E. 
Published: June 2020

Chromophobe pituitary adenomas arise from adenohypophysial cells and fail to exhibit cytoplasmic staining with conventional acid or basic dyes by light microscopy. The aim of the present work was to study the electron microscopic features of these tumors, to separate them into distinct entities and to correlate their fine structural appearances with secretory activity.Among 48 surgically removed various pituitary adenomas 30 tumors were found which, based on the tinctorial characteristics of the cytoplasm, corresponded to chromophobe adenomas. For electron microscopic investigation pieces of these tumors were fixed in 2.5 per cent glutaraldehyde in Sorensen's buffer, post fixed in 1 per cent osmium tetroxide in Millonig's buffer, dehydrated in graded ethanol and embedded in Epon 812. Ultrathin sections were stained with uranyl acetate and lead citrate.By electron microscopy it was possible to separate chromophobe adenomas into 3 distinct entities: 1) adenomas consisting of sparsely granulated growth hormone cells (7 cases).
Pericytic Alterations in Cerebral Infarction
Authors: Dodson Ronald F. , Tagashira Yukio , Chu Lena W. F. , Scates Ronald W. 
Published: June 2020

The pericyte is a nonendothelial cell type which is in close association with the capillary bed and is surrounded by basement membrane. Earlier concepts based on light microscopy lead to the hypothesis that this cell type formed a type of investment around the vessel. Ultra structural investigations have shown this concept to be invalid but the function of this cell type is yet to be determined.Earlier work from our laboratory compared the ultra structural characteristics of pericytes from various areas in normal animal brain; our present aim is to define pericytic response in acute cerebral infarction.The adult baboons utilized in this experiment were subjected to a transorbital occlusion of the right middle cerebral artery for respective periods of 2, 3, 4, 5 and 24 hrs. At the end of the period of occlusion the clip was removed and the animals were perfused (intra-cardiac) with a 500 ml solution of 3% glutaraldehyde in 0.1 M phosphate buffer.
Aspects of Myocardial Regeneration in Notoopthalmus Viridescens
Authors: Philpott D. , Corbett R. , Person P. , Becker R. 
Published: June 2020

While obtaining blood samples from the common newt, Notoopthalmus viridescens, it was observed that at least one-third of the heart could be excised and the animal would still survive. Up to fifty per cent of the blood is lost resulting in circulatory stasis which lasts about an hour. Following this circulatory pulsations and capillary flow are slowly reestablished.Heart samples were obtained five minutes, one hour, two hours, three hours, and twenty-four hours after heart resection. Fixation was in gluteraldehyde followed by osmium tetroxide and embedded in vestopal. Samples were also taken at seven, fifteen, and thirty minutes and counterstained with ruthenium red to obtain information on possible polysaccharide alterations.Erythrocytes are trapped in the clot formation and those adjacent to the myocardial tissue appear to become attached and undergo extensive modification (Fig. 1-3). Pseudopods are sent out from the erythrocytes and extend into and onto, the surface of the myocardium increasing muscular-RBC contact (Fig. 2-3).
Initial Light Effects on Chloroplast Ultrastructure in Soybeans
Authors: Crang Richard E. , Colin Budd G. , Ashbaugh Patrick H. , Noble Reginald D. 
Published: June 2020

Light induced changes in chloroplast volume and thylakoid membranes have been documented in a few plants by light and electron microscopy, as well as with the use of a Coulter counter. We wish to demonstrate that significant structural changes occur in soybean chloroplasts mediated both by genetically dictated levels of photosynthetic pigments, and by light intensity and duration as examined by TEM and an electronic image analyzer.A comparison was made of a field variety (Harasoy) with strain T219 soybeans which genetically segregate into three phenotypes: dark green (DG), light green (LG), and a lethal yellow (LY). All plants in mineral nutrient media were maintained under 12 hr. photoperiods for six weeks prior to sampling. LY plants were grafted to DG at 3-5 days postgermination. Interveinal leaf discs were stamped from sixth node trifoliate leaves prior to illumination and fixed for TEM as were samples at varying time intervals up to 1 hr.
Invasion of Soybean Root Cells in Culture by Rhizobium japonicum.
Authors: Dan Raveed  , Minocher Reporter  , Grace Norris  
Published: June 2020

The initiation of association between cultured soybean root cells and Rhizobia shows specificity under proper conditions of culture. The establishment of these culture conditions for symbiotic association have been described previously. The compatible plant cells produced a filamentous extracellular material which was capable of trapping Rhizobia. Non-compatible cells did not produce extracellular material and were not invaded. In this presentation we have followed the effect of Rhizobial invasion on the wall morphology of the soybean root cells in suspension cultures. Changes in the morphology of the soybean cell walls were then examined as follows.Harosoy root cells were grown in liquid culture in Gamborg's B-5 medium for two weeks. Rhizobium japonicum strain 138 was added to the culture for another 3 days. For this purpose, fixation was carried out by adding glutaraldehyde to the medium to a final concentration of 2%. The cell clumps were fixed 1 hr.
Virus-Like Particles in Spirometra Sp. from a Case of Human Sparganosis
Authors: Sun C.N. , Daly J.J. , White H.J. , Barron A.L. 
Published: June 2020

Mueller and Strano have reported finding virus-like particles lining the walls of excretory ducts in plerocercoid (sparganum) larvae of the pseudophyllidean tapeworms, Sparganum proliferum, from a human host, and Spirometra mansonoides and Spirometra mansoni, from animal hosts. Although human sparganosis caused by these species is distributed world-wide, only 50 cases have been officially reported in the United States. A sparganum in a nodule from the outer aspect of the right thigh of a 30 year-old male in Arkansas has recently been described which is believed to be either S. mansonoides or S. mansoni. Since the previously studied material of these two species were from non-human hosts, this worm afforded the opportunity to examine a non-proliferating sparganum from a human host for the presence of virus particles.The worm, which was 90 mm long and 1 mm wide, was fixed in neutral buffered formalin and post-fixed with buffered 2% osmium tetroxide.
Dynamic Compaction of Rapidly Solidified Al-6%Si Powder
Authors: Allen Robert M. , Smugeresky John E. 
Published: June 2020

The production of alloy powders by processes involving rapid solidification can yield powder particles which exhibit highly-refined microstructures desireable from a mechanical properties standpoint. Unfortunately, traditional methods for compacting powders into parts often cause significant coarsening of the starting powder microstructure. Alternative methods such as dynamic compaction (the shock-loading of the powder under high stresses) are under study as means of preserving the fine-scale of the starting microstructure throughout the manufacturing of a fully-dense bulk part.The purpose of the present work was to examine the microstructures developed by the dynamic compaction of rapidly-solidified Al-6%Si alloy powders. The powder was prepared from cast alloy using an ultrasonic gas atomizer. Particles < 250 μm in diameter were sieved to produce uniform size splits for the compaction study. Dynamic compaction was carried out with a gas gun device which imposed a shock stress of ∼4 GPa on a powder sample, producing a fully-dense compact 30 mm in diameter and 5 to 6 mm thick. Microstructural characterization was carried out using a JEOL 35CF SEM and a 200CX STEM, both equipped with energy-dispersive x-ray spectrometry systems.
Applications of CCEM to Environmental Health Problems
Authors: Lee R. J. , Walker J. S. 
Published: June 2020

Electron microscopy (EM), with the advent of computer control and image analysis techniques, is rapidly evolving from an interpretative science into a quantitative technique. Electron microscopy is potentially of value in two general aspects of environmental health: exposure and diagnosis.In diagnosis, electron microscopy is essentially an extension of optical microscopy. The goal is to characterize cellular changes induced by external agents. The external agent could be any foreign material, chemicals, or even stress. The use of electron microscopy as a diagnostic tool is well- developed, but computer-controlled electron microscopy (CCEM) has had only limited impact, mainly because it is fairly new and many institutions lack the resources to acquire the capability. In addition, major contributions to diagnosis will come from CCEM only when image analysis (IA) and processing algorithms are developed which allow the morphological and textural changes recognized by experienced medical practioners to be quantified. The application of IA techniques to compare cellular structure is still in a primitive state.
High-Temperature Oxidation of 310 Stainless Steel
Authors: Roy Tapan 
Published: June 2020

Austenitic stainless steels find application in heat exchangers, furnace parts, exhaust systems and other such high temperature applications because of their good corrosion resistance at elevated temperatures. This is believed to be because of a passive film of α-Cr2O3 that forms on the surface. Silicon is usually added to afford better scaling resistance. The steel under investigation (AISI # 31000) has minor alloying additions of manganese, silicon and titanium in addition to chromium(25 wt%) and nickel(20 wt%).Annealed and polished 3 mm discs as well as bulk specimens were oxidized at temperatures between 700°C and 900°C in dry oxygen at low pressure. Kinetic studies were performed using a CAHN 1000 microbalance. The 3 mm discs were back-thinned for TEM studies while the bulk specimens were used for SEM observations.
Routine Determination of X-Ray Detector Efficiencies Using Submicron Spheres of Pure Materials
Authors: Kelly Thomas F. 
Published: June 2020

The purpose of this paper is to outline an approach to routine determination of x-ray detector efficiencies over the entire applicable energy range that may be used on any transmission electron microscope.BACKGROUNDThe quantification of x-ray intensities using the ratio technique can be accomplished [see, for example, 1] using a relation of the form:Here, for element A, CA is the composition in the sample as a weight fraction, kA is the x-ray generation constant (see below) which contains only sample-dependent information, eA is the detector efficiency for characteristic x-rays which contains only detector-dependent information, and lA is the measured x-ray intensity in a characteristic line.
Scanning Electron Microscope Evaluation of Hair Dye Effects on the Cuticle Cells of Canine Hair
Authors: Al-Bagdadi F. , Ruhr L. , Archibald L. , Titkemeyer C. 
Published: June 2020

Skin and hair are exposed to environmental factors such as pollutants sun & water(Garcia et al 1978). Hair care products are designed to reduce the damage of environmental influences and for cosmetic reasons. Hair dye products are brought into contact with the hair shaft and the scalp, and on occasions, may penetrate as deeply as the hair roots (Stuttgen 1981). Some of the constituents of hair dyes have been related to skin allergies, nervousness and toxicity (Stuttgen 1981).Only in recent years, in part due to the rising demands for scientific documentation of advertising claims has interest been focused on the development of reliable measurements for the safety of hair dye products.The hair cuticle cells are critical to the preservation of the physical integrity of the hair fibers of the cortex (Wolfram 1972). The scant and controversial information on the effects of hair dye products on the hair shaft and on the epidermis led to this investigation. This study, was conducted by the use of scanning electron microscopy, of mixed-breed dogs subjected to intensive usage of hair dye products reports the changes of the cuticle of the hair shaft and the epidermis.
The role TEM in a government laboratory serving industrial clients
Authors: Malis Tom 
Published: June 2020

The challenge of meeting demands for enhanced performance while maintaining a competitive price has become the norm for industries producing engineering materials. A government laboratory intending to assist such industries in a formal manner must adapt its policies, structure and capabilities as the needs of its clients change. TEM would come under close scrutiny in this process because of the relatively high financial and intellectual investment required to produce good results. The following project examples illustrate secondary, but quite important aspects of the prime goal of solving the client's problem(s). They include judicious facility/methodolgy upgrading (including in-house development and external networking), fruitful interactions with project scientists (including accurate prediction of resource usage) internal and external marketing, and dealing creatively with personnel shortages, all while producing what is hopefully the ‘good science’ needed for institutional and individual recognition!Fig 1 shows typical precipitates in a pipeline steel for which the distribution and composition vis-a-vis various microalloying elements were crucial to the mechanical behavior of the product (via austenite grain size control). Before acquisition of a suitable in-house TEM, university work was funded which demonstrated the complex nature of coprecipitation in these steels, a fact not then appreciated by the steel industry. Subsequent in-house work built upon these findings to the point where characterization of such precipitates has become a most useful component of formalized collaborations with steel companies in that both resource usage and delivery of useful information have become quite predictable.
Prospecting for gold in a VG STEM
Authors: Shoemaker G. L , Sherman W. M. , Duff R. H. , Rothbard D. R. 
Published: June 2020

A calcined pyritic gold ore concentrate was examined using both ion–milled and ultramicrotomed samples to determine the distribution of gold and the porosity of the matrix supporting the gold. Examinations of the same specimen prepared by different techniques yielded complementary information about the overall characteristics of the material.Figure 1 is a secondary electron image (SEI) of a piece of roasted pyritic ore. The particles are highly porous with morphology suggesting that the iron pyrite (FeS2) particles virtually exploded when labile sulfur was released during oxidative calcination. The particles produced by this process are not large enough to permit ordinary solid specimen preparation techniques. Therefore, a compacted bar of material was made by compressing the powder with a binder to form a disk which was subsequently impregnated with epoxy in a PARR bomb under isostatic pressure of a few thousand psi. From this dense material two types of specimen were prepared, one by diamond knife ultramicrotomy and the other by standard thin foil techniques. For the latter, the sample was sliced with a diamond saw, core–drilled into 3mm disks, polished to about 100μm, dimple ground, and Argon ion milled to perforation. This yielded specimens which show the porosity and connectivity of the iron oxide frameworks formed during calcination. Figure 2 is a 10,000X annular dark field (ADF) image of an ion–milled particle taken with a VG HB501 STEM. The channel structures evident in this image are easily related to the SEI image in Figure 1. Figure 3 is a 200,000X ADF image which illustrates the connectivity of individual iron oxide crystallites that form the skeletal structure. This sample was electron transparent only near the central perforation and did not have a large usable area. Also, the outer surfaces ot the particles may have been milled away during specimen preparation and therefore it is not easy to determine where the remaining structures were located in the original particles.
Errors and distortion induced under some operating conditions in a confocal laser scanning microscope (CLSM)
Authors: Leung Harry , Jeun Gwendolyn 
Published: June 2020

Fluorescent beads have been recommended and used frequently as calibration standards for fluorescent microscopy. However, during our work with a CLSM we observed that images of these beads varied in diameter with dianges in illumination level, detector aperture diameter, and signal amplification (gain). In addition, XZ images showed distortion in proportion to such changes.Images from 9 μm fluorescent beads (Excitation Max. @ 458 nm) were collected with a BIORAD MRC600 CLSM attached to a Nikon Diaphot-TMD inverted microscope. A Nikon Planapo 60x (NA=1.4) oil immersion objective was used in all experiments. The beads were embedded in 5 % gelatin to prevent drifting. Using an illuminating wavelength of 488 nm, the beads were optically sectioned at their equators under varying conditions of laser illumination, detector aperture diameter and gain. To eliminate image variations due to size differences among the beads, all images in Fig 1 were collected from the same bead. Those in Fig 2 were from another similar sized bead.