bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scanning Electron Microscopy of Human Articular Cartilage
Authors: Redler I. , Zirany M.L. , Mansell J. 
Published: June 2020

Specimens of human normal and osteoarthritic cartilage obtained during surgical procedures were washed with normal saline to remove gross debris and synovial fluid, fixed in 0.1% glutaraldehyde in Ringer's solution for periods varying between one and four hours, dehydrated in graded acetone solutions and air dried. They were coated with a layer of carbon(100A°) and gold palladium alloy(200A°) and examined in a JSM-U3 SEM.The articular surface of normal cartilage appeared undulated and was composed of a dense irregular network of fibers approximately 0.1 micron thick.(Fig.1) Ridges on the surface measuring between 2 and 6 microns in width were frequently noted in a parallel, intersecting, or random pattern.
The Chatterbox: A Device for Hearing Chatter as Sections are Cut
Authors: McCutchen C. W. , Tice Lois W. 
Published: June 2020

Ultramicrotomists live in a state of guerilla warfare with chatter. This situation is likely to be permanent. We can infer this from the history of machine tools. If set the wrong way for the particular combination of cutting tool and material, most if not all machine tools will chatter.In more than 100 years since machine tools became common, no one has evolved a practical recipe that guarantees avoiding chatter. Rather than follow some single very conservative rule to avoid chatter in all cases, machinists detect it when it happens, and change conditions until it stops. This is possible because they have no trouble telling when their cutting tool is chattering. They can see chatter marks, and they can also hear a sometimes deafening noise.
Similarities of the Embryonic Liver and Hepatoma in the Human
Authors: Weide G. C. Vander , Burns W. A. , Geschickter C. F. 
Published: June 2020

The human embryonic liver and hepatocellular carcinoma (hepatoma) have been infrequently studied at the ultrastructural level. It has been mentioned that there probably is an ultrastructural similarity between embryonic-fetal liver and hepatoma, but this has not been adequately documented in the literature. We wish to report the fine structural similarities we have seen between the embryonic liver and hepatocellular carcinoma.The outstanding similarity is the appearance of the cellular membrane. This is differentiated into microvilli indicating increased activity. The majority of the microvilli are notably elongated. The hepatocytes do not demonstrate a compact arrangement and cellular attachments are infrequent. Bile canaliculi, when observed, appear large with prominent microvilli. The rough endoplasmic reticulum is relatively increased and prominently arranged in stacks. Glycogen is not readily apparent. Lipid-like vacuoles are seen in the cytoplasm.
Ultrastructural Evaluation and Pathophysiology of Testicular Sertoli Cell Neoplasms from Dogs With a Syndrome of Hyperestrogenism
Authors: Capen C. C. , Martin S. L. 
Published: June 2020

A syndrome of feminization associated with testicular neoplasms has been reported frequently in male dogs but occurs rarely in man and other species. Although an excessive secretion of estrogenic hormones has been suspected on the basis of clinical and pathologic findings, elevated circulating levels have not been demonstrated conclusively. The specific objective of this investigation was to evaluate ultrastructural1y functional Sertoli cell neoplasms from 5 male dogs with feminization and to correlate these findings with the results of estrogen assays.The affected testes were enlarged, irregularly lobulated, firm and were retained in the abdomen of all dogs (Fig. 1A). The neoplastic cells were spindle-shaped or polyhedral and formed distinct tubules separated by a delicate connective tissue stroma (Fig. 1B).
Ultrastructural Localization of Cholesterol in Human Arteriosclerosis
Authors: Sekhri Karta , Mills Clint , Younes Henry 
Published: June 2020

Several reports have appeared recently demonstrating a technique for the localization of cholesterol in a variety of tissues. The technique is based on the premise that free cholesterol reacts with digitonin to form cholesterol digitonide which appears as needle-like crystals or spicules under the electron microscope.In order to study the fine structure of the aorta, surgical biopsies from several patients (ranging in age from 45 to 68 years) and with clinical evidence of arteriosclerosis were fixed promptly in Flickinger's fixative (2% formaldehyde, 2.5% glutaraldehyde) containing 0.2% digitonin but buffered with .1M sodium cacodylate. After fixation for 3 hours aortic samples were washed in cacodylate buffer and post fixed in buffered osmium tetroxide for 2 hours & embedded in Epon-Araldite.
The Morphology of Vacuolated Cells in the Liver Following Administration of Vitamin A.
Authors: Minick Odell T. , Yokoo Hidejiro , Batti Fawzia 
Published: June 2020

Vacuolated cells in the liver of young rats were studied by light and electron microscopy following the administration of vitamin A (200 units per gram of body weight). Their characteristics were compared with similar cells found in untreated animals.In rats given vitamin A, cells with vacuolated cytoplasm were a prominent feature. These cells were found mostly in a perisinusoidal location, although some appeared to be in between liver cells (Fig. 1). Electron microscopy confirmed their location in Disse's space adjacent to the sinusoid and in recesses between liver cells. Some appeared to be bordering the lumen of the sinusoid, but careful observation usually revealed a tenuous endothelial process separating the vacuolated cell from the vascular space. In appropriate sections, fenestrations in the thin endothelial processes were noted (Fig. 2, arrow).
Preparation of Amyl Acetate and Acetone Labile Eggs From Parasitic Nematodes For Scanning Electron Microscopy
Authors: Specian Robert D. , Allison Venita F. , Ubelaker J. E. , Martin J. H. 
Published: June 2020

The structure and composition of parasitic nematode eggs, particularly the shells, are of interest to various investigators. Egg morphology is widely used for species identification where sacrifice of the host is not desirable. Scanning electron microscopy (SEM) allows surface sculpture patterns on eggs of closely related species to be observed and aids in identification. The egg shell, in many species of parasitic nematodes, is composed of a proteinchitin-lipid complex which, unfortunately, is labile in many organic solvents including those routinely employed in the preparation of samples for SEM by the critical point drying method.The present study is concerned with the fine surface morphology of eggs from Toxocara canis (Werner, 1782), Toxocara mystax (Zeder, 1800), and Ascaris suum Goeze, 1782, as revealed by SEM after several preparative procedures.
Scanning Electron Microscopy of Dried and Acid Treated Shells of Difflugia
Authors: Eckert Barry S. , McGee-Russell S. M. 
Published: June 2020

Difflugia lobostoma is a shelled amoeba. The shell is an external structure of considerable mass which presents the animal with special restrictions in cell locomotion which are met by the development of active pseudopodial lobopodia containing, apparently, an organized system of thick and thin microfilaments (Eckert and McGee-Russell, 1972). The shell is constructed of sand grains picked up from the environment, and cemented into place with a secretion. There is a single opening through which lobopods extend. The organization of the shell was studied by scanning electron microscopy (SEM).Intact shells or animals with shells were dried by the critical point method of Anderson (1966) or air dried, after primary fixation in glutaraldehyde.
Occurrence and Anatomy of Dense Axillary Cells at the Juncture of the Shoot Apical Meristem and Leaf Primordium in Maize
Authors: Graham Effin T. 
Published: June 2020

The test plant was a single cross hybrid maize (Zea mays), WF9 X 38-11. Shoot apices were sampled at the three-leaf stage of seedling growth. The tissues were fixed 72 hr in cacodylate-buffered (0.025 M, pH 7-3) 5% glutaraldehyde, and were postfixed 3 hr in buffered 2% osmium tetroxide and 1 hr in aqueous 1% uranyl acetate. Dehydration was done in a long series of acetone solutions, 10% to absolute. Embedding was done in a low viscosity epoxy resin, and the sections were stained with lead citrate. All steps from fixation to embedding were done at room temperature.The accompanying figure depicts a group of 3 dense cells located at the base of the axil separating the lower flank of the apical dome and the leaf primordium.
Cryoprotection of Irradiated Specimens
Authors: Box Harold C. 
Published: June 2020

Breedlove and Trammell predict that visualization of molecules by electron microscopy will prove impossible because in the imaging process the molecular architecture will be destroyed Their contention has stimulated considerable debate. In this paper we wish to consider one aspect of the problem, namely, can the effects of radiation damage be minimized by maintaining the sample at low temperature during observation? In this discussion low temperature implies 4.2°K (boiling point of liquid helium at atmospheric pressure) or lower.Low temperature will not, of course, prevent the ionization of molecules by high energy electrons. Electron spin resonance (ESR) studies on a variety of biological compounds do suggest, however, that much less atomic rearrangement occurs at low temperature.
Surface Ultrastructure and Topochemistry of Parasitic Platyhelminths
Authors: Lumsden Richard D. 
Published: June 2020

The “cuticle” of tapeworms and trematodes is, in reality, a cellular syncytium, referred to in the recent literature as a tegument. The external limiting membrane is coated with a layer of carbohydrate-rich polyelectrolytes. In its structure and cytochemistry, this coating of the tegument plasmamembrane closely resembles the ubiquitous glycocalyx of more conventional animal cell types. This paper will review some of the cytological features of tapeworm and trematode body surfaces, focusing on the contributions of the glycocalyx to the functional properties of the host-parasite interface.Lacking a gut, tapeworms utilize the tegument alone for chemical interchange with the host. Attendant to this function is a brush border containing a number of enzymes and transport mechanisms.
Electron Diffraction of Wet Retina Rod Disc Membranes
Authors: Hui S. W. , Matricardi V. R. , Parsons D. F. 
Published: June 2020

Electron diffraction is extremely useful in studying membrane preparations in microscopic quantities. Although certain biological membranes, especially those occured in natural lemella form, have been subject to X-ray diffraction studies, so far no electron diffraction study of wet membranes had been reported, apart from a preliminary attempt made in this laboratory.! The reasons had been: 1) The inability to keep the specimen in its natural state during observation, and 2) The naturally occured lemella of membranes such as nerve myelin, retina rod and chloroplast are usually too thick for the electron beam to penetrate.We report here our preliminary results on an electron diffraction study of the disc membranes of whole wet retina rod outer segments, using the 1 Mev electron microscope at the U.S. Steel Research Center at Monroeville, Pa., with a hydration stage built by this laboratory for that microscope.
Electron and Light Microscopy of Wet Unstained Mammalian Cells
Authors: Matricardi V.R. , Parsons D.F. 
Published: June 2020

Dynamically pumped hydration stages have been developed for electron microscopes. These devices are able to maintain the specimen under a controlled atmosphere (e.g. 100% relative humidity) while being viewed by the electron beam. These devices preserve the pressure differential by using apertures to impede the flow of gas escaping into the column. If adequate pumping is provided the stage can maintain the specimen at a pressure of one atmosphere while the pressure in the column is of the order of 10−4 torr.We have already obtain d electron micrographs of whole wet cells by using the United States Steel high voltage microscope (see figures one and two), but have not yet been able to visualize cytoplasmic streaming or brownian motion within the cell.
Structural Specializations of Sarcoplasmic Reticulum in Skeletal Muscle
Authors: Waugh R. A. , Spray T. L. , Sommer J. R. 
Published: June 2020

The sarcoplasmic reticulum (SR) in muscle is a complex system of tubules in which several regions of discrete structural specializations can be distinguished, e.g. junctional SR (terminal cisternae), extended junctional SR, intermediate cisternae and fenestrations. This study reports the presence of two of these in locations where they have not been described previously.The discovery of additional locations of SR fenestrations was substantially aided by the fortuitous filling of the SR by lanthanum which, in addition, provided a negative stain of the intraluminal contents of the SR. The preparatory techniques were quite routine.
Keratinocyte Cell Membrane of the Freeze-Fractured Human Epidermis
Authors: Hashimoto Ken , Parker Malcolm V. 
Published: June 2020

Freeze-fractured keratinocyte membrane of the human epidermis revealed a relatively particle(arrows)-rich A-face (A) and a relatively particlepoor B-face (B)(Fig. 1). However, these so-called membrane-associated particles are not numerous even on the A-face, as compared with those of other tissues.When the nexus or gap junctions were fractured, in most cases the B-face showed clustered cobblestone particles (c), instead of pits (Fig. 1). Cobblestone particles were 70-135 A in diameter and 0-25 A in height (Fig. 1). Much taller particles (50-70 A in height) were very often admixed (Fig. 1). In some instances. a macule of cobblestone particles (C) was seen in the neighborhood of a macule of depressed particles (D) showing the same dimensions (Fig. 2).
Ultrastructural Changes in Gonadotrophs of the Albino Male Rat after Castration or Treatment With Cyproterone Acetate
Authors: McArthur N. H. 
Published: June 2020

Forty four animals were subdivided into the following groups with three animals per group, except for the intact group which contained five animals: Group 1. Intact; 2. Castrated and injected for 5 weeks with 1.25 mg testosterone beginning on the day of castration; 3-7. Castrated adults killed 1, 2, 3, 4, and 5 weeks postcastration; 8-12. Cyproterone acetate (10 mg daily in benzyl benzoate-castor oil) treated for 1, 2, 3, 4, and 5 weeks duration; 13. Castrated newborns killed as adults, and 14. Castrated new borns killed as adults, after daily injections of 1.25 mg of testosterone for 5 weeks.Following decapitation the adenohypophyses were rapidly removed and fixed in 0.2M phosphate buffered Acrolein-Glutaraldehyde- Paraformaldehyde, postfixed in osmium tetroxide, stained en bloc with 2% uranyl acetate, and embedded in araldite-epon. Lead citrate stained sections were examined in RCA EMU-3c and RCA EMU-4b electron microscopes.
The Application of Ultracryotomy to Immunocytochemistry
Authors: Painter R. G. , Tokuyasu K. T. , Singer S. J. 
Published: June 2020

A technique for localizing intracellular antigens with immunoferritin conjugates directly on ultrathin frozen sections of glutaraldehyde-fixed tissues has been developed. This method overcomes some of the limitations of previously described procedures, since it avoids drastic fixation, dehydration and embedding procedures which could denature many protein antigens.Briefly cells or tissues were fixed with glutaraldehyde (0.5 to 2% for 1 hr), and ultrathin frozen sections were cut and mounted on grids covered with carbon-coated Formvar film by the procedure described previously. Such sections were stained with ferritin-antibody conjugates by methods described elsewhere.
Structure of crystals in dental enamel and synthetic hydroxyapatite
Authors: McLean J. D. , Nelson D. G. A. 
Published: June 2020

Biological apatites in dental enamel, dentine and bone closely resemble, in chemical composition, the mineral hydroxyapatite with the unit cell Ca10(PO4)6(OH)2. Substitutions occur frequently, e.g. fluoride in place of hydroxy groups, carbonate for phosphate, and with other elements such as magnesium, zinc, strontium, and lead instead of calcium. The substituents are known to influence the response of the material to attack by dilute organic acids and are, therefore, of importance in the process of dental caries.The sub-lattice resolution available with some modern electron microscopes makes it feasible to attempt detection of the effect of substituted groups on the structure of the hydroxyapatite crystals. As a starting point in such a venture we have obtained high-resolution images of apatite crystals and used computer image calculation techniques to interpret the micrographs at near-atomic resolution.
Dislocation dissociation in low-angle spinel boundaries
Authors: Ostyn K.M. , Carter C.B. 
Published: June 2020

It is well known that in the spinel structure a perfect dislocation can dissociate into two partial dislocations with collinear Burgers vectors :(1)The two partial dislocations, which have the same character as the perfect dislocation, are separated by a stacking fault in the cation sublattice only. In ceramic materials, unlike fcc metals, dissociation of dislocations can occur by a climb mechanism in addition to, or instead of, dissociation by glide. Climb dissociation of perfect dislocations into two or more partials with collinear Burgers vectors has been observed in e.g. yttrium iron garnet and sapphire. Previous studies in spinels, deformed at high temperatures, emphasize climb dissociation and dissociation of mixed character. Dissociation of screw dislocations in stoichiometric MgAl2O4 spinel could not be resolved and hence no experimental measurements of the dissociation width have been reported.
Twinning in γ-Al2O3
Authors: Tucker Dennis 
Published: June 2020

The spinel structure is well known for (111) twins. This twinning can be described as a reflection with respect to a (111) plane, as a rotation about a [111] direction by 60° or 180°, or as a rotation of 180° about a <112> axis. According to Hornstra, spinel twins can be bounded by two types of stacking faults (Type I and Type III). These stacking faults are part of an extended dislocation, as shown in Figure 1.Table 1 shows the extended ABC notation of the spinel lattice. Referring to Figure 2, in Type I twinning, oxygen ion planes shear in [112] directions and result in an ABAB... stacking sequence. Type II twinning, in which the oxygen ion plane shear direction is [011], results in an FCC stacking arrangement. In Type III twinning oxygen ion planes shear in the [121] direction, resulting in an ABAB... stacking sequence. In types I and III, due to electrostatic considerations, the direction the cations move differs by 60° from that which the oxygen ions move.
Electron microscopy studies of plasma-sprayed materials
Authors: Subramanian K.R. , King A.H. , Herman H. 
Published: June 2020

Plasma spraying is a technique which is used to apply coatings to metallic substrates for a variety of purposes, including hardfacing, corrosion resistance and thermal barrier applications. Almost all of the applications of this somewhat esoteric fabrication technique involve materials in hostile environments and the integrity of the coatings is of paramount importance: the effects of process variables on such properties as adhesive strength, cohesive strength and hardness of the substrate/coating system, however, are poorly understood.Briefly, the plasma spraying process involves forming a hot plasma jet with a maximum flame temperature of approximately 20,000K and a gas velocity of about 40m/s. Into this jet the coating material is injected, in powder form, so it is heated and projected at the substrate surface. Relatively thick metallic or ceramic coatings may be speedily built up using this technique.
HREM of interfaces and defects in semiconductors
Authors: Sinclair R. 
Published: June 2020

It is recognized that interfaces constitute a most important component in semiconductor-based devices and that lattice defects adversely influence the performance of such materials. A basis for understanding these features requires intimate knowledge of their local structure and chemistry which can be provided to a large degree by high resolution electron microscopy (HREM). This article reviews some recent work in this area and indicates where alternative techniques can supplement the information provided by HREM.High quality specimens are required for this work. They can be made by traditional means such as ion-beam milling or chemical polishing, although one must take care when using the former to avoid artifacts introduced by the energetic ion beam. Cross-sectioning is necessary to obtain topographic detail of interfaces, the procedure for which is somewhat more involved. Some details of this technique have been described previously.
Voltage contrast: A powerful tool for VLSI circuit diagnosis
Authors: Stivers A. R. 
Published: June 2020

The advent of very large scale integration (VLSI) presents many new problems for integrated circuit (I.C.) diagnosis. Some I.C.s have over 100,000 transistors with less than 100 external leads with which the transistors can be tested. The geometries are now as small as 3 μm, smaller than can be probed mechanically. Along with the size, node capacitance and current drive are also reduced making a probe's capacitive load very detrimental to rise-time measurements. New processes have many layers of interconnect, leaving more and more of the circuit below passivation and therefore inaccessible to a mechanical probe, even after the removal of scratch protection. VLSI challenges I.C. diagnosis with more internal circuitry that becomes smaller and less accessible to conventional probes.Voltage contrast is an electron beam voltage probing technique especially suited to VLSI circuits. A properly modified SEM, used in the voltage contrast mode, provides both high resolution images of circuit voltages and also voltage waveforms of particular nodes.
The high temperature reaction behaviour of biotite in pelitic xenoliths, Mull, Scotland: An AEM study
Authors: Brearley Adrian J. , Champness P.E. 
Published: June 2020

Analytical electron microscopy has been used to study the mechanisms of metamorphic reactions in xenoliths of Moinian pelitic schist from a dolerite sill, Mull, Scotland. of particular interest has been the reaction behaviour of biotite mica during this low-P, high-T metamorphism. The biotite (∼k1.77(Mg1.81Fe3.26) Al3.65Si6O20(OH)4) shows a considerable darkening under the optical microscope and is, on occasions, almost completely black. High magnification examination indicated that the biotite had partially reacted and was intergrown with its reaction products on a very fine scale. Attempts to identify the new product phases by electron microprobe were unsuccessful.Examination of several conventionally ion-thinned foils of biotite has provided important data on the nature of the reaction processes and reaction products involved. It has been shown that the biotite reacts on a highly localised scale and that equilibrium has not been reached. Only at the very edges of the grains is there any evidence of a reaction involving adjacent phases, usually quartz.