bluuebunny/crossref_metadata_2025 huggingface dataset:
TEM Analysis of Long-Period Polytypes in SiC—S
Authors: Shinozaki S. , Sprys J. W.
Published: June 2020

In reaction sintered SiC (∽ 5um average grain size), about 15% of the grains were found to have long-period structures, which were identifiable by transmission electron microscopy (TEM). In order to investigate the stability of the long-period polytypes at high temperature, crystal structures as well as microstructural changes in the long-period polytypes were analyzed as a function of time in isothermal annealing.

Each polytype was analyzed by two methods: (1) Electron diffraction, and (2) Electron micrograph analysis. Fig. 1 shows microdensitometer traces of ED patterns (continuous curves) and calculated intensities (vertical lines) along 10.l row for 6H and 84R (Ramsdell notation). Intensity distributions were calculated based on the Zhdanov notation of (33) for 6H and [ (33)3 (32)2 ]3 for 84R. Because of the dynamical effect in electron diffraction, the observed intensities do not exactly coincide with those intensities obtained by structure factor calculations. Fig. 2 shows the high resolution TEM micrographs, where the striped patterns correspond to direct resolution of the structural lattice periodicities of 6H and 84R structures and the spacings shown in the figures are as expected for those structures.
Physical, Chemical, and Crystallographic Characterization of Anodic Coatings on High Strength Aluminum Base Alloys
Authors: Herfert R. E. , McDevitt N. T.
Published: June 2020

Durability of adhesive bonded joints in moisture and salt spray environments is essential to USAF aircraft. Structural bonding technology for aerospace applications has depended for many years on the preparation of aluminum surfaces by a sulfuric acid/sodium dichromate (FPL etch) treatment. Recently, specific thin film anodizing techniques, phosphoric acid, and chromic acid anodizing have been developed which not only provide good initial bond strengths but vastly improved environmental durability. These thin anodic films are in contrast to the commonly used thick anodic films such as the sulfuric acid or "hard" sulfuric acid anodic films which are highly corrosion resistant in themselves, but which do not provide good initial bond strengths, particularly in low temperature peel.

The objective of this study was to determine the characteristics of anodic films on aluminum alloys that make them corrosion resistant. The chemical composition, physical morphology and structure, and mechanical properties of the thin oxide films were to be defined and correlated with the environmental stability of these surfaces in humidity and salt spray. It is anticipated that anodic film characteristics and corrosion resistance will vary with the anodizing processing conditions.
The Role of Acyl Transferases Concerned with Phospholipid Synthesis in Membrane Biogenesis
Authors: Barrnett Russell J.
Published: June 2020

The acyl transferases concerned with the synthesis of phosphatitic acid (the first two steps of phospholipid synthesis) survive glutaraldehyde fixation and exposure to cytochemical reagents for the localization of Coenzyme A as indicated by biochemical experiments with 14C labelled or unlabelled Palmytil CoA and 14C labelled or unlabelled α-glycerophosphate. This allowed the development of several cytochemical methods for the demonstration of CoA as the acyl group of Acyl-CoA was transferred to an acceptor molecule during phospholipid synthesis. With these methods, the acyl transferases concerned with phospholipid synthesis were localized in the tissues in which membrane biogenesis was rapidly occurring.
Exogenous Perioxidase Localization in Irradiated Arteries
Authors: Hampton James C. , Rosario Benjamin , Adee Roy R.
Published: June 2020

Mice were exposed to 1500 R X-irradiation and sacrificed on days 1,2,3,3.5 and 4 days postexposure. Two to 3 min before sacrifice each mouse received 5 mg horseradish peroxidase (Sigma type II) in 0.5 ml saline by intrasplenic injection. Tissues were fixed in glutaraldehyde-formaldehyde and incubated according to the method of Karnovsky for histochemical localization of horseradish peroxidase (HRP). Unirradiated tissues and irradiated but unincubated tissues were used as controls.

Figure 1 shows only moderate staining of the internal elastic lamina (IEL) in a small branch of the mesenteric artery at 3 days postirradiation. No evidence of deposits of HRP reaction product was observed in either the endothelium or smooth muscle of the media.
Ultracytochemistry of Carbonic Anhydrase (CAH) in Erythrocytes and Intestinal Epithelium
Authors: Lightfoot F. G. , Cassidy M. M. , Jackson M. J.
Published: June 2020

Since the transport of fluid and weak electrolytes by the small intestine is markedly inhibited by acetazolamide we have studied the cytochemical localization of carbonic anhydrase (CAH) in rat jejunum using the erythrocyte as a model system. Pieces of jejunal tissue were glutaraldehyde-fixed, frozen to -20C and 10 micron sections were obtained with a cryostat microtome. Human erythrocytes were similarly fixed, saline-rinsed and embedded in gelatin which was then treated in the same manner as tissue.

The histochemical reaction product in light microscopy sections is CoS derived from the precipitation of catalysed CoCO3 formation. The reaction time was 8 minutes and the visible CAH activity in both erythrocytes and jejunum (Fig. 1, 2 and 6) was abolished by 1 X 10-4M acetazolamide.
Electron Microscopic Observations on Smooth Muscles of Cat Nicitating Membrane
Authors: Ishikawa Harunori , Yamada Eichi
Published: June 2020

The cat nictitating membrane is commonly used for physiological and pharmacological study, since its smooth muscles are virtually all innervated by sympathetic nerves. Thus, morphological studies at the fine structural level have been focussed to the innervation of the nictitating membrane, but not to the smooth muscle proper.

The nictitating membranes of adult cats were fixed in situ in protruded state with 2% formaldehyde and 2% glutaraldehyde in 0.1 M cacodylate buffer (pH. 7.3). The tissues were then dissected out to continue fixation in the same buffer. After rinse in 10% sucrose in the same buffer, the tissue blocks were postfixed in 1% OsO4 and embedded in Epon.
An Ultrastructural Study of the Proliferation Patterns of the Reserve Cells of the Human Cervix Uteri
Authors: Sohda Takanori , Saito Hiroshi , Asano Goro , Fukushi Katsunari , Suzuki Katsuya , Aihara Kaoru , Yajima Gompachi , Nagata Tokio
Published: June 2020

Recently, the functional aspect as well as morphological aspect of the reserve cells in the cervix uteri drew much attention in view of the carcinogenesis in squamocolumunar junction. In this communication, the authors elucidate the ultrastructural features of the reserve cells in patients of various age groups visiting our university hospital and affiliated hospital.

From conventional light microscopic point of view, the reserve cells tend to be pronounced in various pathological conditions, such as the persisting inflammation, proliferative disorders and irritation of hormones. The morphological patterns of the reserve cells from various stage and degree of irritation were observed.
Electron Microscopy in Surgical Pathology
Authors: Lynn Joseph A.
Published: June 2020

Utilization of paraformaldehyde or even formalin fixed surgical specimens in combination with rapid (24 hour) processing techniques allow for electron microscopic evaluation of a number of difficult diagnostic problems in histopathology. The principle diagnostic uses of electron microscopy at the present time are in the following areas: 1) Renal biopsies with deviations from the normal observed primarily in glomeruli (tubular abnormalities have been subjected to less study) including, degree of cellularity, abnormalities (primarily thickening) of the glomerular basement membrane, deposits of various sorts in juxtaposition or within the basement membrane, accumulations of mesangial matrix or “glomerular scar fiber,” cellular changes including fusion of foot processes, and more recently demonstration of viral agents in the following lesions; acute glomerulonephritis, lipoid nephrosis, chronic glomerulonephritis, focal glomerulonephritis, idiopathic membranous glomerulonephritis, lupus nephritis, diabetic glomerulosclerosis, eclampsia, and amyloidosis;
The Dermis of Psoriatic Skin I
Authors: Mottaz Jess H. , Zelickson Alvin S.
Published: June 2020

Current studies in our laboratory on the ultrastructural effects of a topical steroid treatment of psoriasis in human skin have revealed some vascular changes. The psoriatic lesions contained many dilated capillaries lying close to the basal lamina. Several of these capillaries were found to have open endothelial cell junctions, and although the steroid treatment did clear up the epidermis leaving it grossly and ultrastructurally normal, the open junctions persisted in the dermis as long as two months after the steroid treatment had been stopped. Open endothelial cell junctions have been reported in Pustular Psoriasis and they were thought to be abnormalities in the arterial capillaries.
Ultrastructural Similarities Between Down's Syndrome Prensile Dementia and Alzheimer's Disease
Authors: Ellis William G. , McCulloch John R. , Corley Charles L.
Published: June 2020

The presenile dementia which almost invariably complicates Down's syndrome after the fourth decade is histologically identical to Alzheimer's presenile dementia. Ultrastructural changes in Down's syndrome dementia (DSD) have not been reported thus far. If DSD meets the rigid ultrastructural criteria established for Alzheimer's disease, then an important predictable age-dependent reservoir of material is available for multi-disciplinary studies of the earliest changes of Alzheimer's disease and aging in the human brain.

Thin slices of brain tissue from a 54 years old woman with DSD were immersed in 4% phosphate-buffered paraformaldehyde (pH 7. 3) 12 hours after death, post-fixed in 1% phosphate-buffered OsO4 and embedded in Araldite. Silver impregnations of adjacent slices revealed the characteristic light microscopic findings of Alzheimer's disease: intra-neuronal neurofibrillary tangles, senile plaques, and granulovacuolar bodies.
Ultrastructure of Oviduct Fimbria Epithelium of the Bovine in Estrus
Authors: Nayak R. K. , Ellington E. F.
Published: June 2020

Few papers on the ultrastructure of the oviduct of ruminant species have been published. To date, only the ultrastructure of bovine oviduct ampulla has been reported. To our knowledge, there is as yet no information available on the fine structural features of the bovine oviduct fimbria epithelium. This report describes the fine structure of bovine fimbria epiithelium during estrus. An attempt has also been made to describe for for the first time the comparative fine structural features of the bovine and porcine oviduct fimbria during estrus. Tissue sections were processed for electron microscopy as described in an earlier paper. The epithelium of the fimbria consisted of ciliated and secretory cells.
Secretory Granules in Ectodermal Cells of Normal and Experimentally Treated Chorio-Allantoic Membranes
Authors: Leffingwell Thomas P. , Leffingwell Lois M. , Dauwalder Marianne
Published: June 2020

The specialized membranes of the Golgi apparatus are thought to be responsible for the biosynthesis of complex (genetically-determined) heteropolysaccharides, coupling of such specific molecules with specific protein and/or lipid moieties, and secretion of the specialized materials. When studying the functions of the Golgi apparatus it may be advantageous to use tissues which are amenable to experimental modification.

Selective displacement of the air space of the chicken egg has long been employed to render the chorio-allantoic membrane (CAM) accessible for experimental purposes. The ectoderm of the normal “dropped” CAM is composed of several types of cells, some of which contain Golgi apparatus that produce granules. These granules are moderately osmiophilic and stain positively for polysaccharides. With appropriate treatment, a thin layer of extracellular material which contains polysaccharides can be demonstrated on the surface of the ectoderm (Fig. 1).
Glutaraldehyde Polymerized with Ammonium Hydroxide as an Embedment
Authors: Pease Daniel C.
Published: June 2020

Previously Peterson and Pease described the polymerization of glutaraldehyde with urea in the presence of substantial amounts of water to produce a useful embedment. For that reaction to yield an insoluble plastic a low pH (≅ 3.5-4.0) is required which we felt might be damaging to proteins, and so affect their subsequent morphology and stainability. Therefore, a way has been sought to develop a comparable plastic that could be polymerized at approximately neutrality.

Ammonia is known to react with the carbonyl groups of aldehydes to form simple addition compounds which, however, are notoriously unstable. They tend to polymerize spontaneously to produce trimolecular products with a general formula as indicated.
Comparative Study of the Fine Morphology of Sensory Receptors in Aspidogaster conchicola and Cotylaspis insignis
Authors: Allison Venita F. , Ubelaker J. E. , Martin J. H.
Published: June 2020

It has been suggested that parasitism results in a reduction of sensory structures which concomitantly reflects a reduction in the complexity of the nervous system. The present study tests this hypothesis by examining the fine morphology and the distribution of sensory receptors for two species of aspidogastrid trematodes by transmission and scanning electron microscopy. The species chosen are an ectoparasite, Cotylaspis insignis and an endoparasite, Aspidogaster conchicola.

Aspidogaster conchicola and Cotylaspis insignis were obtained from natural infections of clams, Anodonta corpulenta and Proptera purpurata. The specimens were fixed for transmission electron microscopy in phosphate buffered paraformaldehyde followed by osmic acid in the same buffer, dehydrated in an ascending series of ethanol solutions and embedded in Epon 812.
The Lateral Giant Fiber to Motor Giant Fiber Synapse in Crayfish
Authors: Stirling Charles A.
Published: June 2020

The lateral giant (LG) to motor giant (MoG) synapses in crayfish (Procambarus clarkii) abdominal ganglia are the classic electrotonic synapses. They have previously been described as having synaptic vesicles and as having them on both the pre- and postsynaptic sides of symmetrical synaptic junctions. This positioning of vesicles would make these very atypical synapses, but in the present work on the crayfish Astacus pallipes the motor giant has never been found to contain any type of vesicle at its synapses with the lateral giant fiber.

The lateral to motor giant fiber synapses all occur on short branches off the main giant fibers. Closely associated with these giant fiber synapses are two small presynaptic nerves which make synaptic contact with both of the giant fibers and with their small branches.
A Base Specific Single Heavy Atom Stain for Electron Microscopy
Authors: Langmore J. P. , Cozzarelli N. R. , Crewe A. V.
Published: June 2020

A system has been developed to allow highly specific derivatization of the thymine bases of DNA with mercurial compounds wich should be visible in the high resolution scanning electron microscope. Three problems must be completely solved before this staining system will be useful for base sequencing by electron microscopy: 1) the staining must be shown to be highly specific for one base, 2) the stained DNA must remain intact in a high vacuum on a thin support film suitable for microscopy, 3) the arrangement of heavy atoms on the DNA must be determined by the elastic scattering of electrons in the microscope without loss or large movement of heavy atoms.
Filamentous Component (Slime) in Coniferous Sieve Elements
Authors: Murmanis Lidija , Sachs Irving B.
Published: June 2020

In the literature, it is agreed that in angiosperm sieve elements, a fibrillar, or filamentous, proteinaceous material is present, but the presence of this material in gymnosperms is not agreed upon. Some authors have reported filamentous material (slime) in Pinaceae by light and by electron microscopy. By contrast, some authors have found no structural component in conifers comparable to the sieve element fibrillar component in angiosperms.

This report is an affirmation that filamentous material is present in Pinus strobus L. sieve elements. The finest filamentous unit, when measurable, appears to range from 40-60 A in diameter (Fig. 1, arrows). These filaments have a tendency to accumulate to various degrees. Generally, they aggregate in two; then the double structure measures 120-160 A in diameter (Fig. 1, double arrows), although the distance between two filaments is not constant.
Structure and Chemical Reactivity of the Warty Layer in Wood
Authors: Baird W. M.
Published: June 2020

Transmission electron microscopy was used to study the structure of the warty layer in wood cells of a hardwood and a softwood species and to monitor the dissolution of this component by chemical treatments. The warty layer is an amorphous, isotropic layer of material that lines the inner surface of the secondary wall in mature cells of many wood species. This layer appears to consist of encrusted globules, hence the name warty layer. Liesel has reviewed the occurrence, morphological and chemical features, origin, and significance of this structure. Figure 1 shows the warty layer of a mature tracheid in balsam fir. Part of the layer here is torn away, exposing the microfibrillar structure of the underlying secondary cell wall. Figure 2 depicts the lumen surface of a vessel element of American beech. Shown in addition to the wart structure here is a lumen-side view of an intercellular pit.
The Hyphal Plexus of Psilotum Nudum Gametophytes
Authors: Walker D. K. , Davis R. W.
Published: June 2020

The subterranean gametophyte thallus of Psilotum nudum, like some other lower vascular plants, forms a mycorrhizal-association with an endophytic fungus. The achlorophyllous prothallium is capable of synthesizing starch while growing in the dark. Presumably, the intracellular fungal hyphae within the prothallial cells aid the gametophyte in obtaining at least part of its basic organic nutrients.

Each of the older Psilotum cells develops a single large body near the center of the cell lumen. These bodies are larger than the nuclei of the prothallial cells, but have similar affinities for acidiphilic dyes. This ultrastructural study of Psilotum gametophyte thalli was begun to determine the nature of these unusual bodies.
Crystalline Regions in Human Hepatocytes
Authors: Weide G. C. Vander , Burns W. A.
Published: June 2020

The presence of cytoplasmic crystals in human hepatocytes is extremely rare and has been reported in a variety of pathological conditions. Only one other case of alcoholic fatty liver has been reported to our knowledge. As their nature, derivation, and significance are as yet unknown this report adds another example of these rare structures.

The patient is a 38 year old negro male with the clinical diagnosis of chronic alcoholism and recurrent thrombophlebitis. Liver function tests were compatible with mild hepatic damage. These were returning to normal when a diagnostic liver biopsy without anesthesia was performed. Light microscopy showed mild fatty metamorphosis and focal portal fibrosis.
Ultrastructure and Development of Rodlet Cells in Gill and Intestine of Walleyed Pike (Stizostedion vitreum)
Authors: Leino Richard L.
Published: June 2020

Tissues from the gut and gill of walleyed pike, ranging in age from birth to one year, reared in tanks separate from mature fish, were examined with the electron microscope for rodlet cells. While these cells are thought to be intercellular parasites (Rhabdospora thelohani) by some investigators, the present study supports the view held by others that they are secretory cells of the fish. Mature and previously undescribed immature rodlet cells were examined.

Mature rodlet cells contain a basal nucleus with a supranuclear Golgi and associated saccules and vesicles. Large club-shaped sacs, the narrow parts of which converge upon an opening in the apex of the cell, comprise much of the cytoplasm. The sacs contain a dense-staining amorphous “core” substance surrounded by less dense material.
Great Increase of Numbers of Virus Particles by Irradiating C3H Mouse Mammary Tumors Transplanted into Male Mice
Authors: Melnick P. J. , Cha J. W. , Samouhos E.
Published: June 2020

Spontaneous mammary tumors in females of a high tumor strain of C3H mice were cut into small fragments that were Implanted into the subcutaneous tissue of the back of males of the same strain, where they grew as transplantable tumors. When about Cm. In diameter daily fractional radiation was begun, applied to the tumors, the rest of the body being shielded by a lead shield. Two groups were treated with 150 and 200 r X-ray dally, of half value layer 0.6mm. copper; a third group was treated with 500 r cobalt radiation dally. The primary purpose was to examine the enzyme changes during radiation, with histochemlcal technics.
Electron Microscopic Observations on the Rescue of SV40 Virus From Transformed Cells
Authors: Glaser Ronald , Farrugia Ross
Published: June 2020

Several laboratories have reported that simian virus 40 (SV40) was rescued from transformed cells when the nonproducing cells were cocultivated or fused in the presence of ultraviolet inactivated Sendai virus (UV-SV), to potentially susceptible cells. Evidence obtained from studies in which nuclei from heterokaryons were isolated and separated on density gradients, indicated that rescued virus was first detected in the transformed nuclei of the heterokaryons formed during cell fusion. The present study was performed to determine how long after fusion SV40 virus particles could be found in the nuclei of the heterokaryons and to investigate the site of rescue by electron microscopy.
The Technique and Uses of Electron Microscopic Denaturation Mapping of DNA
Authors: Schnös Maria , Inman Ross B.
Published: June 2020

The helix coil transition of DNA depends on the base composition. Molecules that have a high A + T content denature at lower temperatures or pH's than those with high G + C content. A similar dependence can be demonstrated at the intra-molecular level; if partially denatured DNA is observed by electron microscopy, individual molecules contain regions of denaturation and these correspond to A + T rich sequences within each molecule. If all the molecules have a similar base sequence then the maps showing the position of denatured sites should be the same. Such has been shown to be the case for λ, P2, 186 and P4 bacteriophage DNA in our laboratory.
A New Model of Freeze Etching Apparatus
Authors: Akahori Hiroshi , Okamura Sadahiko , Nishiura Mitsugu , Uehira Kenzo
Published: June 2020

A new model of freeze etching apparatus has been designed which enabled us to make both freeze fracture and freeze etching replicas of the biological specimens by easy simple procedures.

This model is based on the principle of Bullivant's cold metal block method. It is composed of two-wedge-like brass blocks which are combined in a shape of rectangular prism with'a base 5.5 cm x 6. 0 era and a height of 7.5 cm.

The lower block has a specimen stage to which a small specimen holder made of copper can be fixed. The specimen is put in a small hole of the specimen holder, and this holder is cooled in Freon 12.
Ultrastructure of Frozen Thin Sections of Skeletal Muscle
Authors: Demaree Richard S. , O'Donnell Terrance A.
Published: June 2020

Reliable equipment has just recently become available which permits thin-sectioning of frozen specimens. We have been studying the effects of diet and exercise on skeletal muscle and are using cryoultramicrotomy as a check on fixation, dehydration, and embedding procedures.

Canine triceps or pectineus muscles were obtained using either surgical or needle biopsy techniques. Fresh tissue was diced into 1mm cubes and either frozen fresh or fixed in 2.5% phosphate-buffered glutaraldehyde (5, 10, 15 or 30 minutes). Freezing by immersing specimens in liquid nitrogen consistently produced many ice crystals. However, freezing specimens by immersing them in isopentane cooled with liquid nitrogen produced fewer ice crystals. Cryoprotective agents, such as glycerine, yielded no appreciable improvement in preservation.

Unfixed, frozen tissue was thin-sectioned with the specimen at -90° C, the knife at -30° C, clearance angle 5°, knife edge 55°, at a cutting speed of 2 mm/sec. Fixed, frozen muscle was thin-sectioned at the same temperatures with a knife clearance angle of 7°, knife edge 40°, at a cutting speed of lOmm/sec.
Morphology of the California Encephalitis Virus (CEV)
Authors: Vaituzis Z. , Reichelderfer P.S. , Hetrick F.M.
Published: June 2020

Negative staining technique with potassium phosphotungstate (pH 7.2) and thin sections stained with uranyl acetate (pH 4.2) and lead citrate (pH 11.0) were used to study the fine structure of the prototype strain, BFS-283, of the California encephalitis virus group. The BHK-21 cell line was employed in this study for virus propagation. Monolayers were infected using a multiplicity of infection of 0.1. Following virus adsorption the cells were incubated at 37 C for 48 or 72 hrs. at which times samples were harvested for electron microscopy.

Conventional methods for virus concentration and purification (e.g. centrifugation, cesium chloride gradient centrifugation, dialysis) failed to yield intact virus particles. These preparations contained disintegrating virions averaging 75 nm in diameter (Fig. 1). Treatment of such purified preparations with a 1.0% solution of sodium desoxycholate removed the lipid envelope and associated material revealing a nucleocapsid core of approximately 43 nm (Fig. 2).
Scanning Electron Microscopy of Clostridium Botulinum Under Varying Growth Conditions
Authors: Ewell John B. , McGrath Philip P. , Stevan Lee J. , Wehrung John M.
Published: June 2020

The toxin produced by Clostridium botulinum type A is a well-known and a well-studied neurotoxin but not many of these studies have correlated the morphological changes of the bacteria with toxin production. Toxin production in type A has been related to autolysis as well as carbohydrate source. Furthermore, toxin production can be inhibited or eliminated if growth occurs in the presence of ethylenediamine tetraacetic acid (EDTA). During the past year we have attempted to use the scanning electron microscope for this correlation of toxin production with morphology under varying conditions of cultivation.
As-1 Virus Adsorption to Cells and Spheroplasts ofSynechococcus Cedrorum
Authors: Desjardins Paul R. , Barkley Michael B.
Published: June 2020

The recently described blue-green algal virus (AS-1) infects the unicellular algae,Synechococcus cedrorumandAnacystis nidulans. It has a complex morphology with a polyhedral head and contractile tail. The negative stain technique has been utilized to characterize its mode of adsorption to the cells of one of its hosts (S. cedrorum). Spheroplasts of this host were also prepared to determine whether the virus would adsorb to them as well as to normal cells.

Synchronous cultures ofS. cedrorumwere induced by 3 - 4 days of light-dark alternation. When 75-85% synchrony had been obtained the cells were centrifuged and washed twice in a 0.5 M mannitol - 0.03 M phosphate buffer at pH 6.8. The cells were then treated with 0.05% lysozyme in buffer for 2.5 to 5.5 hrs at 39 C in the dark to induce spheroplast formation.
Hexachlorophene Influence on Ultrastructure of The CNS
Authors: Galey Frank R.
Published: June 2020

Histological studies have demonstrated an hexachlorophene induced change of the cerebral white matter in rats (Kimbrough). The following report is an ultrastructural description of the changes as seen in monkeys, with an attempt to explain the molecular mechanism by which the changes develop.

A dose of 3 mg of hexachlorophene per kg was administered subcutaneously to four juvenile (3-4 yrs) monkeys (Macaca mulatta) twice daily for 3 months. At the end of the experiment four treated monkeys and two stock control monkeys were sacrificed under anesthesia. The head region was perfused with 2.5% glutaraldehyde in a modified Tyrode's solution and tissues were sampled from spinal cord, superior colliculus, thalamus-callosum, cerebellum and optic nerve, and prepared for electron microscopic examination.

Light microscopic examination revealed the development of cystic spaces in the thalamus-callosum samples from all of the treated animals. Optic nerve and spinal cord samples also demonstrated cystic spaces, but not as extensively as in thalamus-callosum.
Some Effects of Oxidant Air Pollutants (Ozone and Peroxyacetyl Nitrate) on the Ultrastructure of Leaf Tissues
Authors: Thomson William W. , Swanson Elizabeth S.
Published: June 2020

The oxidant air pollutants, ozone and peroxyacetyl nitrate, are produced in the atmosphere through the interaction of light with nitrogen oxides and gaseous hydrocarbons. These oxidants are phytotoxicants and are known to deleteriously affect plant growth, physiology, and biochemistry. In many instances they induce changes which lead to the death of cells, tissues, organs, and frequently the entire plant. The most obvious damage and biochemical changes are generally observed with leaves.

Electron microscopic examination of leaves from bean (Phaseolus vulgaris L.) tobacco (Nicotiana tabacum L.) and cotton (Gossipyum hirsutum L.) fumigated for .5 to 2 hours with 0.3 -1 ppm of the individual oxidants revealed that changes in the ultrastructure of the cells occurred in a sequential fashion with time following the fumigation period. Although occasional cells showed severe damage immediately after fumigation, the most obvious change was an enhanced clarity of the cell membranes.
A Micromanipulator for Use in the Column of a Scanning Electron Microscope
Authors: Pawley James B.
Published: June 2020

Used in the secondary electron mode, the Scanning Electron Microscope (SEM) produces an image of the outside surface of a microscopic sample which looks very similar to what one might expect to see if the sample was a diffusely illuminated macroscopic object viewed with the unaided eye. Part of the familiarity of such an image is associated with the fact that one seems to look at the sample rather than through it, as in the case with the conventional electron microscope or the high resolution light microscope. A resulting limitation is the fact that an object of interest cannot be observed if it is below the outer surface. It has been shown (Gane and Bowden 1968) that useful surface hardness information can be obtained on a micro scale by observing the deformation produced when a small stylus, attached to a D'Arsonval meter movement, is brought to bear on the surface of a sample while it is in the SEM.
Microanalysis of the Malpighian Tubule in the Silkworm Bombyx mori
Authors: Thurston E. L. , Russ J. C. , Teigler D.J. , Arnott H. J.
Published: June 2020

Microanalysis in examining thin sections of biological tissue is providing new information in the areas of qualitative and quantitative histochemistry. This technique employs a SEM or TEM, equipped with an energy dispersive spectrometer and a transmitted electron detector. The crystal system in the silkworm was selected for this study in that it could serve as a model for bone formation, excretion, calcium transport, and oxalate metabolism in addition to its being suitable for the solving of some of the problems relating to microanalysis technique.

Specimens were routinely fixed and embedded for TEM, and sections of approximately 1500Å were analysed on a SEM for 400 seconds at 30 KV at 0. 2 nA beam current. The spectra were computer - processed to smooth scatter and remove the contamination peak for silicon. In addition to problems involving contamination there has been uncertainty about the attainable levels of spatial resolution and sensitivity using thin sections.
Analysis of Contrast Reversal in SEM Images
Authors: Coutts M. D. , Levin E. R.
Published: June 2020

On tilting samples in an SEM, the image contrast between two elements, x and y often decreases to zero at θε, which we call the no-contrast angle. At angles above θε the contrast is reversed, θ being the angle between the specimen normal and the incident beam. The available contrast between two elements, x and y, in the SEM can be defined as,

(1)

where ix and iy are the total number of reflected and secondary electrons, leaving x and y respectively. It can easily be shown that for the element x,

(2)

where ib is the beam current, isp the specimen absorbed current, δo the secondary emission at normal incidence, k is a constant, and m the reflected electron coefficient.
Texture and Artifacts in SEM Observations Due to Vapor Coating
Authors: Paulson G. G. , Pierce R. W.
Published: June 2020

Specimen preparation techniques for scanning electron microscopy have not necessarily kept pace with the advances in instrumentation, especially in fields where quantitative measurements are important. Even though many operators have found that nonconducting surfaces can often be examined directly with low voltages and small beam currents, most commonly these surfaces are vapor-coated with 100 to 600 A of a noble metal alloy. More often than not, the coating procedures involve a bit of guesswork as to the final thickness and structure of the vapor coating. The purpose of this research was to illustrate the importance of close control on coating thickness and uniformity in order to minimize artifacts and distortion. Several noble metals and alloys were studied. The results for gold coatings are reported.

Polystyrene spheres of statistically uniform diameters were dispersed on glass slides. The slides were rotated as they were coated by thermal deposition of Au from a W boat at a pressure of 2 x 10-5 torr in a standard oil diffusion pumped vapor coater.
Electron Microscopic Observation of Biological Specimens in Their Native State by Employing Cryogenic Techniques
Authors: Nei Tokio , Yotsumoto Haruo , Hasegawa Yoichi , Nagasawa Yuji
Published: June 2020

In order to observe biological specimens in their native state, that is, still containing their water content, various methods of specimen preparation have been used, the principal two of which are the chamber method and the freeze method.

Using its recently developed cold stage for installation in the pre-evacuation chamber of a scanning electron microscope, we have succeeded in directly observing a biological specimen in its frozen state without the need for such conventional specimen preparation techniques as drying and metallic vacuum evaporation. (Echlin, too, has reported on the observation of surface structures using the same freeze method.)

In the experiment referred to herein, a small sliced specimen was place in the specimen holder. After it was rapidly frozen by freon cooled with liquid nitrogen, it was inserted into the cold stage of the specimen chamber.
A High Vacuum Scanning Electron Microscope
Authors: Bottoms W. R.
Published: June 2020

The vacuum system of any electron optical instrument effects the contamination rate, electron source life, the quality of the electron source which can be employed, vibration amplitudes and stray magnetic field levels. It is particularly important for the scanning electron microscope where the object of primary interest is a specimen surface which can be altered by contamination. If we extend our investigations to employ Auger electron spectroscopy for surface chemical analysis, the requirements on the vacuum system are much more stringent. It is necessary that the chemical composition of the surface monolayer is not appreciably altered during the time required to take Auger spectra. The vacuum level required to accomplish this is dependent on the specimen material and the chemical composition of the ambient gas.

Commercially available equipment can be modified to provide a vacuum environment maximizing the analytical capabilities of the instrument. The gas loads from the specimen and electron gun chambers of the instrument are minimized by utilizing only materials with favorable outgassing rates, and employing a gentle bakeout to remove water and other loosely bound gases on the system surfaces.
A New Design of Scanning Microscope
Authors: Sato Masayuki
Published: June 2020

One of the practical approaches to the design of a scanning microscope is to employ the modular system for the recent versatile applications. The reasons are as follows: Each field of applications requires different sorts of instrument performance and even in a same field, the requirements may be changed as the research progresses. In order to meet these requirements, the instrument should be easily rearranged or modified, and as many new attachments as possible should be developed.

The new scanning microscope JSM-50A has been designed and completed based on this concept. The modules used in this instrument are standardized in width, height and depth and in the mounted in a bin and power supply, and they constitute one unit which can be drawn out with the aid of slide type mounting channels from the cabinet for quick servicing. The width is selectable as single, double, triple and so on according to the built in circuit.
A High-Voltage Terminal for a Field-Emission Gun
Authors: Ziegler N. F.
Published: June 2020

A high-voltage terminal has been constructed for housing the various power supplies and metering circuits required by the field-emission gun (described elsewhere in these Proceedings) for the high-coherence microscope. The terminal is cylindrical in shape having a diameter of 14 inches and a length of 24 inches. It is completely enclosed by an aluminum housing filled with Freon-12 gas at essentially atmospheric pressure. The potential of the terminal relative to ground is, of course, equal to the accelerating potential of the microscope, which in the present case, is 150 kilovolts maximum.
Development of Field Emission Electron Gun for High Resolution 100KV Electron Microscope
Authors: Someya T. , Goto T. , Harada Y. , Watanabe M.
Published: June 2020

The field emission source is one of the most important factors to improve the image contrast in extremely high resolution electron microscopy since it provides high brightness, very small electron source and low energy spread of electrons. In scanning electron microscopy, although the field emission source has been proved to be advantageous in the range of relatively low accelerating voltages, those capable of operating at higher accelerating voltages are now in great demand in order to improve the resolving power up to 3Å or better. In the present work, we have developed a field emission electron gun which is used with an electron microscope of accelerating voltages up to 100KV.

In this development, we first made efforts to improve the method of supplying high voltages in order to eliminate the surge influence on the field emission source which are easily destroyed by a high voltage surge produced by the discharge between electrodes constituting the electron gun.
A Resolution Test Sample for the Scanning Electron Microscope
Authors: Ballard David B.
Published: June 2020

A test sample that satisfies the restrictive specimen criteria discussed previously for a resolution determination of the SEM is essential. At present, the use of a resolution sample made from a specimen well-known to the particular operator who carries out measurements on the subsequent photomicrograph is the usual procedure. The aluminum-tungsten (Al-W) dendritic structure (located at arrow) in Fig. 1 that remains on the crystal surface of the bead resulting from the melting of aluminum on a hot tungsten filament, provides such a specimen.

The dendritic structure found on the Al-W specimen and shown in Fig. 2 is produced by the following technique. A piece of high purity aluminum (99.999%) wire weighing 35 to 40 milligrams is attached to a single coil, approximately 4mm O.D., of a tungsten filament made from 0.5mm (20 mil) single strand wire. The length of the tungsten filament, between the clamped ends of the electrodes in the metal evaporator, is about 6cm.
Electron Accelerators for High-Voltage Electron Microscopy (HVEM)
Authors: Reinhold Günter O.
Published: June 2020

High-voltage electron microscopes are characterized by accelerating voltages in the megavolt range (500 kV and above). Compared to conventional electron microscopes, with voltages up to 200 kV, the high-voltage instruments offer the advantage of improved resolving power (1 to 10 Å) and greater effective penetration of the electron beam. A basic difference between ordinary and high-voltage electron microscopes is the use of an electron accelerator in place of the electron gun to accelerate the electron beam to the required high energy. The resolving power of an electron microscope is determined by the stability of the accelerating voltage, the mechanical precision of the lenses and specimen stages, the stability of the lens supply current and freedom from mechanical vibrations. The symmetrical cascade generator is the only high-voltage dc power supply to meet these requirements with regard to voltage stability and vibration-free performance.
Accelerator for the Arizona 1 MeV Scanning Electron Microscope
Authors: Strojnik Ales , Lewis Peter B.
Published: June 2020

The new accelerator, the basic design of which has been discussed elsewhere consists essentially of the injector system (1,2,4,Fig.1), operating at a constant gradient of approximately 5 x 106V/m, and of nominally 50 accelerating stages (5,6,7), operating at a variable gradient of 105...106 V/m, depending on the total accelerator voltage. Optics of the injector was chosen in such a way as to preserve the desired focal properties of the accelerator in the whole energy range (105...106 V). A telefocus gun after Steigerwald is used. The dimensions are based on data published by F. Braucks, to obtain the crossover at the accelerator exit. A crossover 1 mm in diam at a distance 20 cm from the accelerator exit is measured already at 100 kV with a linear decrease proportional to . In addition an interchangeable Wehnelt/anode configuration of conventional design is available. Hairpin or pointed filaments are heated by alkaline batteries.
High Voltage Electron Microscopy of Integrated Circuit Devices
Authors: Smith P. J. , Troutman H. A. , Raheja R. K.
Published: June 2020

One-MEV transmission electron microscopy has been used to examine the complete structure of individual integrated circuit devices. The use of high voltage microscopy provided sufficient penetration to examine the entire emitter and base regions, while a new specimen preparation technique ensured that the device was uniformly thinned.

As previously reported, a TEM specimen preparation technique has been developed which uses the structure of the device itself to form the thinned sample. This technique has been used to prepare samples which are uniformly thin over the entire area of the device. Thus the complete characterization of the defect structure within the device is possible; this is necessary if a direct relationship between structure and electrical properties is to be made. Samples approximately 3 μ m thick were prepared so that the complete emitter and base regions and part of the collector could be examined by high voltage transmission microscopy. The emitter-base and collector-base junctions were 1.7 μ m and 2.1 μ m deep respectively. The base dopant was boron and the emitter dopant was phosphorous.
Ion Thinning of Sensitive Materials
Authors: Thompson George R.
Published: June 2020

As the list of materials prepared by ion micro milling has increased over the last few years, experience has been gained regarding the families of materials which are most sensitive to ion bombardment. Based on our laboratory experience, it has become necessary to develop certain attachments for ion etching machines which may be used to eliminate or minimize the deleterious effects of this process on sensitive materials. In summary, these mechanisms of damage may be categorized as thermal effects, structural alterations (artifacts), ion damage, surface contamination and differential etching. In addition to citing examples of these various categories, attachments and processing techniques used to protect sensitive materials from damage are summarized.

Thermally sensitive materials were first ion etched under cryogenic conditions in the latter part of 1970. The requirement for ion etching at relatively low temperatures arose in conjunction with research on electronic materials, and the masking employed in conjunction with circuit etching.
Some Multiple Bio-organic Influences Upon the Electron Optical Character of Montmorillonitic Coacervates in Saline Water
Authors: Grant Whitehouse U. , McKee Thomas R.
Published: June 2020

The influence of bio-organics upon the settling rates of clay minerals in saline water was described by Whitehouse, Jeffrey, and Debbrecht in 1960 and the term “coacervate” was used to indicate a “solid-rich” liquid phase in the presence of a “solid-poor” liquid phase in such water. Whitehouse etal. also reported electron microscopical observations of interactions of a specially prepared and analyzed fraction of sodium montmorillonite with some amino acids in the presence of aldohexoses in saline water (pH= 7.3-8.4) at 23°C in 1962 and introduced a “coacervation-adsorption isotherm” for these mechanisms in 1965. In order to study these coacervates in representative form, the critical point technique (Anderson) was first modified for use in electron optical studies of montmorillonitic assemblages by White-house and McCarter in 1958. A typical montmorillonitic “coacervate” is shown in Figure 1.
Effects of High-Energy Ions on Synthetic Quartz
Authors: Comer Joseph J. , Bergeron Charles , Lowe Lester F.
Published: June 2020

Using a Van De Graaff Accelerator thinned specimens were subjected to bombardment by 3 MeV N+ ions to fluences ranging from 4x1013 to 2x1016 ions/cm2. They were then examined by transmission electron microscopy and reflection electron diffraction using a 100 KV electron beam.

At the lowest fluence of 4x1013 ions/cm2 diffraction patterns of the specimens contained Kikuchi lines which appeared somewhat broader and more diffuse than those obtained on unirradiated material. No damage could be detected by transmission electron microscopy in unannealed specimens. However, Dauphiné twinning was particularly pronounced after heating to 665°C for one hour and cooling to room temperature. The twins, seen in Fig. 1, were often less than .25 μm in size, smaller than those formed in unirradiated material and present in greater number. The results are in agreement with earlier observations on the effect of electron beam damage on Dauphiné twinning.
Elevated Temperature Stability of a Lamellar Al-CuAl2 Eutectic Composite
Authors: Pattnaik Amitav , Lawley Alan
Published: June 2020

Since the two phases of a directionally solidified binary eutectic composite are essentially in chemical equilibrium, the microstructure should be stable at elevated temperatures. This effect has been demonstrated in a number of alloys. However, eutectic composites are characterized by physicochemical instability due to the large total interfacial area. The total interfacial energy per unit volume can be reduced by coarsening of the structure, by the growth of existing lower-energy interfaces at the expense of existing higher-energy interfaces, or by the formation of new lower-energy interfaces at the expense of existing interfaces. The present study was made in order to examine these possibilities in a fine-scale lamellar Al-CuAl2 eutectic.

Composites with an interlamellar spacing ≲2 μ were grown at a speed of 11 cm per hour in high-purity graphite crucibles. Exposure temperatures of 490°C, 510°C and 530°C were chosen with time at temperature ranging from 10 to 100 hours.