bluuebunny/crossref_metadata_2025 huggingface dataset:
Scanning Electron Microscopy of the Outer Taste Pore from a Human Tongue
Authors: Kaufman Arenberg I. , Marovitz W. F. , Mackenzle A. P.
Published: June 2020

Increasing use is now being made of the scanning electron microscope for soft biologic tissues. The use of chemical fixation followed by freeze-drying, facilitates surface observations of tissues which otherwise would not be possible.

Four hours following necropsy a sample of human tongue was removed. This specimen was fixed in 10% neutral formalin, postfixed in 1% osmic acid, dehydrated in graded series of alcohol, and evaporated, in vacuo, over a Linde molecular sieve at -30 ± 1°C. The specimen was plated with gold: palladium (40: 60) in a vacuum evaporator to an approximate 200 Å thickness. The emissive mode of the Cambridge Stereoscan Mark II scanning electron microscope was used for this study.
Antiphase Boundaries in Ordered Ni3FE Crystals
Authors: Liu Y. H.
Published: June 2020

Ordered Ni3Fe crystals possess a LI2 type superlattice similar to the Cu3Au structure. The difference in slip behavior of the superlattice as compared with that of a disordered phase has been well established. Cottrell first postulated that the increase in resistance for slip in the superlattice structure is attributed to the presence of antiphase domain boundaries. Following Cottrell's domain hardening mechanism, numerous workers have proposed other refined models also involving the presence of domain boundaries. Using the anomalous X-ray diffraction technique, Davies and Stoloff have shown that the hardness of the Ni3Fe superlattice varies with the domain size. So far, no direct observation of antiphase domain boundaries in Ni3Fe has been reported. Because the atomic scattering factors of the elements in NijFe are so close, the superlattice reflections are not easily detected. Furthermore, the domain configurations in NioFe are thought to be independent of the crystallographic orientations.
Semiconductor X-Ray Detection in the Electron Microscope
Authors: Duff R. H. , Bender S. L.
Published: June 2020

With the introduction of solid state detectors having resolutions of 300 eV or better, the feasibility of an efficient, nongeometry dependent X-ray detector of high resolution became a reality. The use of X-ray detecting systems in conjunction with electron microscopes has been limited to the dispersive type which is highly dependent on geometry or to the gas flow proportional counter which has poor resolution. Recently, high resolution solid state detectors have been used with scanning electron microscopes; however, no use has been made of them in the conventional transmission electron microscope. The usefulness of an elemental analysis together with morphological and crystallographic information is obvious.
High Resolution Scanning Microscopy
Authors: Crewe A. V. , Wall J.
Published: June 2020

We have previously reported on the development of a scanning microscope with a resolution of 20 Å. This instrument has now been improved so that the current point resolution is about 5 Å at 18 Kv.

The microscope consists of a field emission gun followed by a single objective lens (see Fig. 1). The gun produces an image (real or virtual) of the field emission source which is then demagnified by the lens. The focal length of this lens has been shortened from 1 mm to 0.6 mm to produce a second beam crossover at the exit of the lens.
Annealing of Irradiation-Produced Voids in X8001 Aluminum Alloy
Authors: Braski D. N. , Packan N. H.
Published: June 2020

Several detailed studies of voids found in quenched metals have been reported previously, in which the effects of annealing of thin foil specimens in vacuum were observed periodically by electron microscopy. In our investigation, neutron-irradiated samples of X8001 aluminum alloy were observed during annealing at 150° C in a Hitachi HU-11B electron microscope modified for high vacuum operation, The standard tilting hot stage of this instrument was modified so that temperature could be controlled within ±1° C during any one annealing experiment.
Identification of some Events in Bacterial Conjugation of E. Coli
Authors: W. Schreil , R.J. Christensen , B. Felluga
Published: June 2020

In bacterial conjugation in the Escherichia coli system, two cells with heterosexual properties, donor and receptor cells, form a temporary pair and DNA is transferred up to the amount of a whole bacterial chromosome which would represent, if stretched out, a 1 mm long molecule. The physical mode of DNA transfer between two cells which have tight cell walls and cytoplasmic membranes is far from clear.
Osmic Impregnation of Amphibian and Gastropod Photoreceptors
Authors: Eakin Richard M. , Brandenburger Jean L.
Published: June 2020

Friend and Murray found that long osmification of mouse epididymis revealed localized osmium reduction in epithelial cells; in this instance, in only the outer cisternae and vesicles of the Golgi apparatus. Although many substances reduce osmium, aldehydes and compounds with multiple double bonds are particularly active. Knowing that retinaldehyde (vitamin A aldehyde) is a highly unsaturated aldehyde we applied their technique to eyes of tadpoles of two amphibians (Xenopus laevis and Hyla regilla) and to adult eyes of one pulmonate snail (Helix aspersa). Eyes were extirpated, immersed in unbuffered 2% aqueous osmium tetroxide for two or three days at 40°C, and prepared for electron microscopy by rapid dehydration with ethanol, embedment in Epon, and examination of ultrathin sections without further staining.
Ultrastructure of Thin Proteolipid Membranes
Authors: Asunmaa S. K. , Schultz R. D. , Kleist F. D.
Published: June 2020

Protein stabilized membranes from purified ova-lecithin (10% in decane-squalene, 2:1) were formed on the surface of 0. 1 M NaCl containing 10 μg protamine/ml. The ultrastructure (Figure 1) of a phosphotungstate stained membrane reveals a distorted "hexagonal" array of subunits, thin discs with a stained core, 37-45 Å diameter, and 86-97 Å center-to-center distance. These subunits may be related to those observed in intercellular junctions and in the Vibrio fetus cell wall.
Structure and Function of Pancreatic Beta Cells in Streptozotocin Diabetes
Authors: Liss R. H. , Cotton F. A. , Palm P. E. , Kensler C. J.
Published: June 2020

Streptozotocin, an antibiotic with anti-tumor activity, is diabetogenic in rats and hamsters. The present communication is a report on the extent and duration of structural and chemical changes associated with streptozotocin diabetes in rats and hamsters.

Sprague-Dawley male rats and male hamsters (~255 grams) received a single intravenous dose of streptozotocin (100 mg/kg) in citrate buffer. Pre-test and experimental determinations of glycosuria and blood sugar were made. Islet cells from rats and hamsters were prepared for electron microscopy at selected intervals, between 5 minutes and 144 days, after dosage.
Eastern Equine Encephalitis Virus Infection of the Salivary Glands of Aedes Triseriatus Mosquitoes
Authors: Whitfield Sylvia G. , Murphy Frederick A. , Daniel Sudia W.
Published: June 2020

Arboviruses are maintained in nature principally through biological transmission between susceptible vertebrate hosts by hemophagous arthropods; they multiply and produce viremia in vertebrates, and multiply in the tissues of arthropods after which they may be passed on to new vertebrates by bite. In the arthropod, the virus-laden blood meal is directed to the midgut where, generally, virus penetration and preliminary multiplication occurs; subsequently the salivary glands and other tissues are infected by the haemolymph and further multiplication takes place. Vectors continue to harbor and shed virus throughout their life span. Since there has been no description of animal virus replicative events in mosquito vectors, the present study was undertaken to explore the morphologic sequence of infection leading to secretion' of virus in saliva.
Electron Microscopy of the FBJ Osteosarcoma Virus
Authors: Biskis B. O. , Finkel M. P.
Published: June 2020

Finkel, Biskis, and Jinkins reported extraction of a virus (FBJ) from a spontaneous mouse osteosarcoma, in 1966. Although FBJ virus contains the group-specine complement fixing antigen common to viruses of the leukemia-sarcoma complex, in 28 cell-free passages to date in mice it has produced only bone tumors.

In sections of the tumors virus particles appear in extracellular spaces and budding from cell membranes (Fig. 1). Morphologically, FBJ is a Type C virus, as designated by W. Bernhard, and it would be called Muri virus, Sarcomatis according to recommendations of the Provisional Committee for Nomenclature of viruses.
Localization of C-Type Viruses in Preleukemic AKR Mouse Spleen
Authors: Swartzendruber D. C.
Published: June 2020

Attempts to trace injected murine leukemia viruses in mice by electron microscopy are confused by the presence of indigenous virus-like particles of a similar morphology, apparently ubiquitous in inbred strains. In about 90% of AKR mice a spontaneous leukemia, developing at 7 to 9 months, offers an opportunity to study the tissue and cellular distribution of murine leukemia viruses over their lifespan. It is important to discover the site(s) of initial virus-cell interaction in an experimental leukemic model system. Such studies might also contribute valuable clues in searching for similar viruslike particles in human leukemia.
Simultaneous Freeze-Etching of Eight Specimens
Authors: Steere Russell L. , Moseley Michael
Published: June 2020

A specimen cap for the Denton Freeze-Etching Module has been modified (Fig. 1) to permit the easy manipulation and simultaneous freeze-etching of eight specimens. A slot has been cut in one side of the cap to permit the insertion of a brass washer and a thin copper retainer plate above the threads, but below the supporting top of the cap. The inside rims of the washer are elevated, and the end of each specimen holder flange is beveled down and out to the base to form a wedge which can be forced under the washer. Small caps are placed over the specimen in each holder. Specimens are frozen by rapid immersion in Freon 22. The assembled cap is then mounted on a stage, standing in liquid Freon near its freezing point and slightly loosened. The eight frozen specimens, with caps in place, are picked up individually with tweezers and wedged under the washer, lifting it in the process. These operations can be accomplished with cold stage and cap under a dissecting microscope, if desired.
A Highly Stable 150 KV Supply
Authors: Ziegler N. F.
Published: June 2020

A high voltage power supply has been constructed for use with the ORNL Superconducting Microscope described elsewhere in these proceedings. A simplified schematic diagram of the system is shown in Figure 1. The regulator circuit employs a “bouncer” with a cathode-follower output. This configuration results in a low output impedance and the bouncer can thus drive a load capacitance over a wider bandwidth than the conventional common-cathode circuit. The voltage divider for the regulator is a dual unit originally developed to determine the stability of resistive high-voltage dividers. A dual capacitive divider is an integral part of the voltage divider as shown in Figure 1. The dual units have proven to be very useful in practice since one divider may be used in the regulator while the second is used to monitor the noise present on the high voltage. Mercury cells are used as reference elements in the regulator. Wide-band noise on the output is about one ppm at present. Modifications are now under way to eliminate at least two of the known sources of noise in the system.
The Role of Transmission Electron Microscopy in Characterizing the Nature and Behavior of Grain Boundaries
Authors: Murr L. E.
Published: June 2020

Grain boundaries represent the single, most dominant imperfection in structural materials of engineering and industrial importance, and are a controlling factor in the strength of materials. Transmission electron microscopy, combined with the ability to gain direct crystallographic information from associated selected-area electron diffraction patterns, represents perhaps the most effective means for the investigation of the nature and behavior of grain boundaries in solids.

Any segment of a grain boundary has associated with it five degrees of freedom. The electron microscope has the capability to characterize these degrees of freedom and to uniquely define the geometrical and crystallographic nature of a grain boundary. In addition, once the true geometry of intersecting grain boundaries or grain boundaries intersecting with other interfaces is determined, interfacial free energy ratios can be calculated from which the average energy associated with particular types of interfaces can be determined.
Variation of Lattice Spacing with Thickness of Thin Gold Platelets
Authors: Smart D. C.
Published: June 2020

Variation of lattice parameters with crystal size in very small crystals (generally less than 500 Å in size) has been the subject of many research papers over a long period of time. In principle this method should provide a direct experimental measurement of surface tension but in many cases the reported results are contradictory. This fact has been noted in recent reviews, and the abnormal spacings are now generally regarded with considerable reserve. The many reported contradictions arise from a variety of experimental factors which cannot be discussed here. This paper, however, reports new experiments using a different approach which we believe has eliminated the previous experimental difficulties, and conclusively demonstrates lattice parameter variations associated with surface energy. These experiments consist of the preparation of thin, parallel, clean and nearly perfect platelets of Au and the subsequent measurement of the lattice spacings of these platelets as a function of thickness.

The Au platelets were chemically grown by the reduction of chloroauric acid with salicylic acid. Reproducibly clean crystals from 1-5 µ in diameter and ranging in thickness from 80-300 Å were produced.
Scanning Electron Microscopy of Sintered Copper Spheres
Authors: Nyce A. C. , Wehrung J. M.
Published: June 2020

Parts produced by the solid state sintering of compacted or loose metal powders are used widely in such critical applications as nuclear reactor control rods and fuel elements, rocket nozzles, corrosion resistant porous filters, automobile parts and many others of equal importance. However, the mechanisms of mass transport responsible for sintering of metal and ceramic powders remain controversial despite over 20 years of experimental and theoretical studies (1) and (2).

In an effort to elucidate the mechanisms of solid state sintering, Nyce and Liebenthal determined neck growth, shrinkage, B.E.T. surface area, and sintered strength for nominal 48 and 115 micron diameter, nitrogen-atomized, spherical copper particles containing less than 0.2% oxygen. These relationships were determined as a function of sintering time at temperatures of 850°C and 950°C. Nyce and Liebenthal found by assuming a) microscopically smooth surfaces, b) fracture occurring at necks, and c) reasonably uniform necks between spherical particles that strength, shrinkage, and neck growth could be quantitatively described in terms of B.E.T. surface area measurements.
Ultrastructure of Nocardia Astcroides
Authors: Serrano J. A. , de Serrano A. A. , Tablante R. V.
Published: June 2020

A considerable number of quite complete studies on the genus Mycobacterium have been published, particularly those of Imaeda and co-workers, which are concerned not only with problems of ultrastructure but also with correlating those aspects with the chemical composition of the cell wall of these bacteria. Papers on the ultrastructure of the genus Nocardia are relatively few, especially with regard to complete study of the various aspects of arrangement and location of its external structures, cell wall and internal cytoplasmic membrane, mesosomes and division mechanisms. Our aim is to study bacteria belonging to this genus at various stages of growth, choosing several of the most representative types of the groups so far proposed. Up to the present time, we have studied four strains of Nocardia asteroides, 3 of which were isolated in Venezuela by Dr. Salfelder from soil and wood and 1 from ATCC No. 14957. We wish to contribute our findings towards a better understanding of this genus the taxonomic status of which has undergone so much discussion.
Synaptic Specialization in the Cristae Ampullaris of the Frog
Authors: Dunn Robert F.
Published: June 2020

The neurohumoral synapses of the Type II receptor cells of the frog's cristae are of two types: the sphere synapse and the modified conventional synapse. Within the receptor cell, the sphere synapse (analogous to the ribbon synapse) is recognized by the prominent electron dense synaptic sphere which is surrounded by synaptic vesicles (Fig. 1). Immediately below the synaptic sphere, three arciform electron dense structures are present as localized thickenings of the receptor's plasma membrane. In the region of the arciform structures, the plasma membrane of the receptor cell presents a scalloped appearance. The plasma membrane of the connecting neuron also shows a similar scalloped contour opposite the arciform structures, as well as an increase in thickness. The receptor and neuronal plasma membranes are separated by a synaptic gap which varies from synapse to synapse, but remains relatively constant in any given synapse. Several mitochondria are located within the neuron near the sphere synapse, and synaptic vesicles may or may not be present in the neuron. Figure 1 is an example where numerous synaptic vesicles are present in the neuron.
Chloroplast Abnormalities Seen in a Pale Green Mutant of Chlamydomonas reinhardtii
Authors: Symmes Nancy J. , Weaver Ellen C.
Published: June 2020

In the search for life support systems for possible long term manned space flights one must, at some point, investigate photosynthetic systems, and hence the interest in green algae with their ease of care, rapid growth rates, and high efficiency of energy conversion. With the present restriction of weight it would be most advantageous to find an organism with a maximum photosynthetic capability.

A pale green mutant Ac 29 of Chlamydomonas reinhardtii (obtained from Professor Wilbur Ebersold, UCLA) has been studied which has four times the photosynthetic capacity at high light intensities on a chlorophyll basis as the wild type (as based on measurements of CO2 uptake and O2 evolution). In order to try to find some basis for the differences in photosynthetic capacity, comparisons were made between wild type (strain 21gr, obtained from Ruth Sager, Hunter College) and mutant at both the ultrastructural and chemical levels.
Ultrastructure of Alpha-Keratin Microfibrils
Authors: Vacca J. G.
Published: June 2020

Tips from the quills of Erethyon dorsaturn (porcupine) were placed in 0.5 M thioglycollic acid at pH 5.6 for 24 hours, then fixed for 72 hours in 1% OsO4. Quills were also prepared without the thioglycollic acid treatment. The material was dehydrated in a series of ethyl alcohols and embedded in Spurr Low Viscosity Embedding Medium. Sections were cut on a Reichert 0mU2 ultramicrotome and stained for 40 minutes at 37°C with saturated lead hydroxide. Electron micrographs (primary magnification 150,000 x) were taken with an A.E.I. EM6B electron microscope at 60 KV equipped with 25 μ and 50 μ objective apertures and an anticontamination device. Focal series of silver to silver gray sections were taken with a 0.1 μ change of focus (1 click of fine focus control). For the Markham rotation technique a constant speed motor (The General Industries Co., Elyria, Ohio) and a Strobatac (Model 1538-A, General Radio) was used.
Ultrastructural Changes in Acutely Rejecting Cardiac Allografts
Authors: Popovic N. A. , Hattler B. G. , Jervis H. R. , Ward P. , Currier C. B. , Alexander J. L.
Published: June 2020

Cardiac allografts have been shown to elicit both in man and in the experimental animal a vigorous and prompt immune response that is poorly understood and remains the main obstacle to the clinical utilization of the heart in organ transplantation. The present study represents a further attempt to delineate mechanisms of damage in hearts being acutely rejected as studied in an experimental dog model utilizing electron microscopic (EM) and histochemical techniques.

The model consisted of canine hearts heterotopically transplanted to the necks of recipient dogs previously immunized to donor tissues by repeated intradermal injections of washed donor spleen cells followed by skin grafts until lymphocytotoxic antibody titers were greater than 1/2000 and white graft reactions were seen. At the time of transplantation, prior to removal of the heart, an initial Silverman needle biopsy was taken from the donor ventricle. During this period the animal was well oxygenated and the heart was beating in a normal sinus rhythm.
The Fine Structure of the Cockroach Subgenual Organ
Authors: Moran David T.
Published: June 2020

Insects are abundantly endowed with mechanoreceptors, sense organs that transduce mechanical stimuli into nerve impulses. Like most cockroaches, Blaberus discoidalis is highly sensitive to vibrations of the substrate on which it walks. This sensitivity is thought to be due in large part to the subgenual organ — an intricately constructed mechanoreceptor located near the proximal end of the tibia. The exoskeleton of the cockroach is secreted by a layer of epidermal cells which enclose the haemocoele of animal's open circulatory system. The subgenual organ is a thin, fan-shaped flap of tissue which is suspended from the epidermis and occludes much of the dorsal blood space in the hollow leg. It is therefore surrounded by blood on all sides; its position renders it susceptible to minor displacements of the surrounding fluid medium. Highly modified epidermal cells which are packed with hundreds of parallel microtubules support the subgenual organ as a ligament. The cells which compose the bulk of the organ are populated with a few mitochondria and many microtubules.
Possible Differentiation of Lens Fibers in Rabbit Lenses Maintained in Organ Culture
Authors: Unakar N.J. , Reddan J.R. , Bell R.M. , Harding C.V.
Published: June 2020

The adult ocular lens offers a unique system to study the process of cell division and/or differentiation. Mitosis is principally confined to the equatorial region of the lens and in the normal sequence of events the cells in this region divide, traverse the terminal cell cycle and differentiate, i.e., synthesize lens specific proteins. The cells which reside in the central epithelium are, on the other hand, blocked in the Go state but can be triggered to divide by culture in a medium which contains rabbit serum. Previous studies have defined the biochemical and morphological changes which precede and accompany DNA synthesis and mitosis in the cultured rabbit lens. This paper describes certain morphological changes which occur in the peripheral region of rabbit lenses which have been exposed to rabbit serum for 35 hours.
Cuticular Folds in three Species of Lycopersicon as Observed by Scanning and Transmission Electron Microscopy
Authors: Spurr Arthur R.
Published: June 2020

Differences in the architecture of the cuticle of Lycopersicon esculentum, L. peruvianum, and L. pennellii (the cultivated and two wild species of tomato, respectively) were examined by scanning electron microscopy. The cuticle of L. esculentum was also studied by transmission electron microscopy to assist in the interpretation of cuticular folds.

For SEM, fresh styles were removed from flowers just prior to anthesis and attached to specimen stubs and promptly observed. For TEM, the material was fixed in glutaraldehyde-Os04, dehydrated in ethanol, embedded in epoxy resin, and section-stained with uranyl and lead acetates. Observations were confined to the upper portion of the style.
Morphological Examination of a Herpes-type Virus Indigenous for Tree Shrews
Authors: Brunschwig J. P. , McCombs R. M. , Mirkovic R. , Benyesh-Melnick M.
Published: June 2020

A new virus, established as a member of the herpesvirus group by electron microscopy, was isolated from spontaneously degenerating cell cultures derived from the kidneys and lungs of two normal tree shrews. The virus was found to replicate best in cells derived from the homologous species. The cells used were a tree shrew cell line, T-23, which was derived from a spontaneous soft tissue sarcoma. The virus did not multiply or did so poorly for a limited number of passages in human, monkey, rodent, rabbit or chick embryo cells. In the T-23 cells, the virus behaved as members of the subgroup B of herpesvirus, in that the virus remained primarily cell associated.
Purification, Physical Features, and Electron Microscopy of Celo Virus
Authors: Stenback W. A. , Anderson J. P. , McCormick K. J. , Trentin J. J.
Published: June 2020

Chicken-embryo-lethal-orphan (CELO) virus is an avian adenovirus shown to be oncogenic in newborn random bred and inbred hamsters (1). Transformation of human cells by this agent has been reported (2). This virus is ubiquitously present in chickens and market eggs and is therefore considered to be a potential candidate for cancer etiology in man.

Virus for the present study was inoculated into 10-day CELO-free embryonated eggs, and crude stocks consisted of 72-hr allantoic fluid harvests. To 80 ml of crude stock was added 0. 8 gm Na-deoxycholate and 4. 0 ml of 0. 25% trypsin, and the mixture incubated at 37 C for 30 min.
Studies of Mouse Mammary Tumor Virus by Ferritin-labeled Antibody
Authors: Kodama T. , Williams W. C. , Hales R. L. , Dmochowski L.
Published: June 2020

Morphological, biological, and immunological studies indicate a possible interrelationship between mouse mammary tumor virus and leukemia virus in the development of mouse mammary tumors. Electron microscope studies have shown the presence of both mouse mammary tumor virus (type B) particles and mouse leukemia virus (type C) particles in mouse milk, in tissues, and in tissue cultures from spontaneous and induced mouse mammary tumors (Dmochowski, L., et; al.: Carcinogenesis, A Broad Critique, Williams and Wilkins Co., Baltimore, p.211, 1967;., Dmochowski, L., et al.: J.Nat. Cancer Inst., 40:1339, 1968).
Ultrastructure of the Synovial Microvasculature in Rheumatoid Arthritis (ra) and Systemic Lupus Erythematosus (SLE)
Authors: Ralph Schumacher H.
Published: June 2020

Synovial vascular alterations have been suggested to be important in the pathogenesis of both RA and SLE (1). Although vascular changes have been described by light microscopy the presence of significant ultrastructural changes has been questioned (2). This report describes an EM study of needle synovial biopsies from 5 patients each with classical RA and SLE. Specimens were promptly fixed in Karnovsky's paraformaldehyde-glutaraldehyde diluted 1:1 with 0.1 M cacodylate buffer at pH 7.4, washed in buffer, post-fixed in Palade's osmium-veronal, dehydrated with alcohol, embedded in epon, cut, and stained with lead citrate and uranyl acetate. Vascular changes were seen in both groups with some findings common to both diseases. Basement membranes were multilaminated. (Fig.l). This was not seen in normal rabbits and monkeys but was also present in other human joint diseases including degenerative arthritis. Venular endothelium was active appearing with filopodia extending into the lumen and with gaps demonstrable between endothelial cells (Fig.2,3). Platelets occluded some gaps (Fig.2).
Modular Concepts in the Design of Electron Optical Systems
Authors: Fairbanks J.R.
Published: June 2020

A practical approach to the design of complex machinery is to standardize parts as much as possible. This approach is equally valid for the design of scientific instruments such as electron microscopes, provided there is no sacrifice in performance for the completed instrument. As an example, the illustration shows modular parts used elsewhere in an electron optical column, which are organized by design in this particular case to perform as a second condenser lens.

Consider the upper polepiece. This modular piece is used in nine other places in the column; once in the lower condenser as shown, twice in the upper condenser, twice in the objective lens, twice in the second projector, twice in the third projector, and once in the first projector. Since all the polepieces are identical, they are all of the highest quality needed in the most critical lens, the objective. The optical system thus benefits from standardized high quality lenses, (which ultimately is the user's benefit), and the instrument maker benefits from the economy of making pieces in replicate.
The Effect of Chromatic Aberration on the Visibility of Defect Clusters in Irradiated Metals
Authors: Noggle T. S. , Oen O. S. , Crump J. C.
Published: June 2020

In recent years considerable attention has been directed to the interrelation of chromatic aberration and energy loss on the resolution of electron microscopes; however, the related problem of the effect of chromatic aberration and energy loss on the visibility of defect structures appears to have not been considered and is the subject of this paper.

Electron microscope studies of the defect clusters present in fast neutron irradiated copper and heavy ion irradiated gold have shown that the apparent cluster size distributions are affected by changes in the specimen thickness, accelerating voltage, objective focal length and aperture size in a manner that indicates that chromatic aberration in conjunction with the energy spread due to energy loss of the image forming electrons is responsible for the differences noted. Figure 1 shows cluster size distributions for fast neutron irradiated copper and heavy ion irradiated gold in which it is clear that the apparent densities of cluster sizes less than about 50 Å in diameter are affected by the experimental parameters noted above. The qualitative effect of the experimental parameters on the apparent densities of the smaller defect clusters follows closely the behavior expected from calculations of the radius of the disc of confusion using the equations shown in Fig. 1 and tabulated in the tables. The curves in Fig. 1 indicate that there is no sharp cutoff in the cluster density, and accordingly, it is not clear what criteria should be employed in relating the experimental parameters to the experimental results.
High Voltage Microscopy in Paleontological Studies – Graptolites
Authors: Berry W. B. N. , Takagi R. S. , Thomas G. , Jurica D. J.
Published: June 2020

Transmission electron microscopy has seldom been used in studies of fossils, and to date, no electron diffraction work has been reported. Because of the limited transmission power of the 100 kV electron microscopes (<lμ), the techniques which have been used to prepare specimens have followed standard biological methods, including ultra-thin sectioning and staining. High voltage electron microscopy on the other hand allows examination of considerably thicker specimens (up to 5μ at 500 kV) and is particularly useful in studying fossils e.g. it is often not necessary to section pieces of the fossil. Minimal preparation is advantageous because materials that have been interred in rocks of the earth's crust for millions of years are commonly brittle and distort or break while being sectioned with the microtome.
Application of HVEM to the Study of Radiation Damage in Metals
Authors: Laidler J.J. , Mastel B.
Published: June 2020

One aspect of high voltage electron microscopy, which is normally considered to be a disadvantage in the usual materials studies, is the production of atomic displacements or radiation damage in the specimen. This imposes limitations on beam current, accelerating voltage used or time of observation if one is concerned with measurements which are sensitive to the presence of point defects. This limiting aspect can be turned into a major asset, however, in the case of investigations involving the study of irradiation effects in metals and alloys. The HVEM has a special advantage in such studies, since it makes possible the continuous observation of the accumulation of crystal defects during the process of irradiation.
Structural Dependence of Electrical Conductivity of thin Tellurium Films
Authors: Dinno Mumtaz A. , Schwartz Manuel , Giammara Beverly
Published: June 2020

Capers and White made an extensive study of the growth of tellurium thin films deposited on different substrate materials but did not measure the electrical properties of the deposited films. Berryman studied the effects of film thickness, deposition rate, and substrate temperature on the electrical properties but there is no evidence that these results were correlated with structural studies. Dutton presented a method for growing large grains using a gold monolayer as nucleation sites and for these special films related electron transport properties with structure. The present study undertakes the determination of conductivity over a range of thicknesses extending from 350 Å to 2800 Å on a substrate initially at room temperature, for both annealed and nonannealed films. In addition, some work was done with quenched and heated substrates at 700 Å thickness.
Determination of the Axial Poisson’s Ratio For 1 Mil Nylon and Polyester Fibers Using the SEM
Authors: Hubbard James L. , Rushing Eugene V.
Published: June 2020

A technique has been devised for measuring the axial Poisson's ratio, vLT, of 1 mil transversely isotropic man-made polymeric fibers using the scanning electron microscope. This study was a part of a larger one in which techniques were developed for measuring the five independent elastic constants necessary to describe the mechanical behavior of such fibers.

To facilitate the making of these measurements a stressing stage was constructed for the Cambridge Stereoscan Mark II. This stage, shown in Figure 1 replaces the normal sample block in the specimen chamber drawer and utilizes the normal tilt and rotation controls to tilt the stage and activate the stressing jaws respectively.
Morphology of Oligomer Crystals
Authors: Chen Y. T. , Bartkus E. A.
Published: June 2020

Poly(ethylene terephthalate) (PET), contains approximately 1.5% oligomer (cyclic trimer). When films are heated the oligomers tend to migrate out and crystallize on the surface. The isolation and identification of oligomer has been reported; the crystal structure has been studied by x-ray and electron diffraction. Except for some optical work, however, the crystal morphology of oligomer has not been carefully studied. This paper gives some results of an electron-microscopy study of the morphology of oligomer crystals.

PET films were annealed in an oven at different temperatures for different lengths of time. Oligomer crystals were observed after one hour of annealing at temperatures as low as 100°C; they became visible after only a few minutes of annealing at 200°C.
A New Technique to Complement Tem Measurements of Heavy Ion Produced Swelling
Authors: Johnston W. G. , Rosolowski J. H. , Rosolowski J. H. , Lauritzen T.
Published: June 2020

The development of rapid and reliable techniques for measuring void swelling produced in metals by heavy ion bombardment is an important part of our investigation of possible alloys suitable for fast reactor structural materials. Conventional transmission electron microscopy (TEM) measurements of void numbers and sizes with sterescopy has permitted us to observe up to about 50% swelling without evidence of saturation for certain alloys bombarded with 5 MeV nickelions. Measurement of swelling beyond this was not feasible with standard TEM techniques since void size had become comparable to the foil thickness (Fig. 1). In the case of high voltage electron microscopy where greater foil thicknesses can be used, the overlapping of many voids limited measurement. There are additional disadvantages and limitations of TEM measurement techniques. Throughout the range of swelling, inhomogenity of void distributions hampers the selection of representative areas (Fig. 2).
A Computer Method for Facilitating Rapid Quantitative Use of the Philips 300 Goniometer Stage
Authors: Tzeng Wen-Shian , Strutt P. R.
Published: June 2020

A computer method has been developed which facilitates the rapid use of the Philips 300 goniometer stage for quantitative diffraction contrast analyses of lattice imperfections in thin-foil specimens. Using this method it is a straightforward matter to obtain 20 (or even more) different two beam conditions on a single randomly oriented grain in a polycrystalline specimen. Furthermore, the method avoids ambiguity in determining the sense of the atomic displacement of planar defects. Thus it is particularly useful for the precise characterization of stacking faults and anti-phase boundaries. The generality of the method enables it to be used for thin-foil specimens with any crystallographic structure. Basic steps involved in the actual computer program are briefly summarized.
Photostimulated Exoelectron Emission from Slip Lines—A New Microscopy of Metal Deformation
Authors: Baxter William J. , Rouze Stanley R.
Published: June 2020

Plastic deformation of metals enhances photoelectron emission, an effect known as photostimulated exoelectron emission. It has been proposed that the electrons are emitted from microcracks produced in the oxide. We have observed this phenomenon directly in a photoemission electron microscope (PEM) and shown conclusively that such emission does indeed originate from cracks in the oxide at slip lines.

The PEM consists essentially of two magnetic and one electrostatic immersion lens. The sample is illuminated with ultraviolet radiation, and the photoemitted electrons are imaged on a fluorescent screen. A Channeltron Electron Multiplier Array provides image intensification. The sample is deformed in situ by bending to produce tensile deformation of the surface under study.
Characterization of Coherent, Ordered Precipitates in Nickel-Base Alloys
Authors: Kear B. H. , Oblak J. M.
Published: June 2020

A nickel-base superalloy is essentially a Ni/Cr solid solution hardened by additions of Al (Ti, Nb, etc.) to precipitate a coherent, ordered phase. In most commercial alloy systems, e.g. B-1900, IN-100 and Mar-M200, the stable precipitate is Ni3 (Al,Ti) γ′, with an LI2structure. In A lloy 901 the normal precipitate is metastable Nis Ti3 γ′ ; the stable phase is a hexagonal Do2 4 structure. In Alloy 718 the strengthening precipitate is metastable γ″, which has a body-centered tetragonal D022 structure.

Precipitate Morphology

In most systems the ordered γ′ phase forms by a continuous precipitation re-action, which gives rise to a uniform intragranular dispersion of precipitate particles. For zero γ/γ′ misfit, the γ′ precipitates assume a spheroidal.
Microstructure of a CoCrNiTa Alloy System
Authors: Howe A. P. , Asgar K. , Bigelow W. C.
Published: June 2020

The effect of tantalum additions to a 40-30-30 CoCrNi alloy has been studied by electron diffraction, transmission and scanning electron microscopy, and energy dispersive x-ray analysis in an attempt to identify the microstructure associated wit£ mechanical properties determined by a previous investigator.

Samples were prepared by conventional investment casting techniques and thinned electrolytically in perchloric acid-ethanol solution at 20-35 volts for transmission electron microscopy. This solution also etched the surfaces of the specimens sufficiently to yield good sca ning electron micrographs.

Energy dispersive k=ray analysis showed that the castings contain an average of 19% more Ta, 8% more Cr, 9% less Co and 6% less Ni than the weighed amounts.
A Study of Contrast For Biological Electron Microscopy
Authors: Chen C. S.
Published: June 2020

The lack of contrast in the images of unstained and hydrated biological specimens is a serious limitation. Therefore, a quantitative study of contrast for various image modes has been undertaken. However, rather than perform time consuming experiments directly on the microscope, I have chosen to predict the contrast theoretically using a smaller number of experimental measurements to test the accuracy of the theoretical predictions.

Fig. 1 shows the scattering distribution of carbon films at 100kV, and indicates that,at a given carbon thickness, the inelastic scattering passed by the aperture is almost ten times the elastic scattering. Thus, the image formed is incoherent, and highly chromatically aberrant. Due to the small elastic scattering, phase effects are expected to be small.
Effects of Vibration on the Preparation of Ultrathin Sections
Authors: Blum Joseph M. , Gargiulo Edward P. , Sawers J. R.
Published: June 2020

It is now well-known that chatter (Figure 1) is caused by vibration between the microtome arm and the diamond knife. It is usually observed as a cyclical variation in “optical” density of an electron micrograph due to sample thickness variations perpendicular to the cutting direction. This vibration might be induced by using too large a block face, too large a clearance angle, excessive cutting speed, non-uniform embedding medium or microtome vibration. Another prominent cause is environmental vibration caused by inadequate building construction. Microtomes should be installed on firm, solid floors. The best floors are thick, ground-level concrete pads poured over a sand bed and isolated from the building walls. Even when these precautions are followed, we recommend an additional isolation pad placed on the top of a sturdy table.
Morphological Basis of the Disparity Between Muscle Length and Sarcomere Length in the Myocardium
Authors: Adomian G.E. , Chuck L. , Pannley W.W.
Published: June 2020

Sonnenblick, et al, have shown that sarcomeres change length as a function of cardiac muscle length along the ascending portion of the length-tension curve. This allows the contractile force to be expressed as a direct function of sarcomere length. Below L max, muscle length is directly related to sarcomere length at lengths greater than 85% of optimum. However, beyond the apex of the tension-length curve, i.e. L max, a disparity occurs between cardiac muscle length and sarcomere length. To account for this disproportionate increase in muscle length as sarcomere length remains relatively stable, the concept of fiber slippage was suggested as a plausible explanation. These observations have subsequently been extended to the intact ventricle.
Ultrastructural Aspects of Sodium Transport in Rat Myometrium
Authors: Garfield R.E. , Daniel E.E.
Published: June 2020

The energy-dependent formation of spherical membrane vesicles which serve as cation binding sites was originally proposed for tenia coli. More recently, membrane vesicles in rat myometrium have been postulated to serve as sites for an ATP-dependent, ouabain-insensitive system controlling cell volume as well as sites in which the classical Na+-K+-activated ATPase functions.

In the present study, strips of rat myometrium were incubated in Krebs-Ringer solution at 25°C with and without various metabolic and transport inhibitors. Tissues were removed from the incubation solution at various times and analyzed for ATP, water and ion contents. Some pieces of tissue from the same uterine horns were prepared for the electron microscope for measurements of vesicle size and number.
Morphologic Changes of Rabbit Ovarian Follicles Following Copulation
Authors: Cherney David D. , DiDio Liberato J. A , Motta Pietro
Published: June 2020

The interrelated processes enabling the ovum to be released from the mammalian ovary have been the subject of many investigations, which resulted in the advancement of several hypotheses; none, however, can as yet totally explain the morphophysiologic events leading to and responsible for ovulation.

This investigation deals with a comprehensive light and electron microscopic study of the morphologic changes related to ovulation in the rabbit. Moreover, an attempt is made to establish a correlation between the modification of the follicle and perifollicular structures and their most likely causal factors.

The morphology of the non-stimulated follicle is illustrated in Figure 1. Following copulation, follicles were removed at 2,4,6,8 and 10 hours, processed for electron microscopy, and comparable electron micrographs taken. As expected, the apex of the preovulatory follicle exhibited the most dramatic changes since it is the site where ovulation takes place.
Estrogen Stimulated Rhesus Monkey Oviducts in Organ Culture
Authors: Anderson Richard G. W. , Brenner Robert M.
Published: June 2020

Work in this laboratory has established that oviducts of hypophysectomized or oophorectomized rhesus monkeys become atrophied and the epithelial surface becomes undifferentiated. Injections of these animals with 30 ng/day of estradiol benzoate stimulates the redifferentiation of the epithelial surface. After ten days of estrogen treatment, approximately 5% of the epithelial cells are ciliated and 50% are secretory. During ciliogenesis there is a series of complex changes which result in basal body replication and cilia formation. The stages of ciliogenesis are convenient markers for the effects of estrogen, as well as other drugs, on the oviduct.

An organ culture system has been developed which can be used to study metabolic changes in the differentiating oviduct and to study ciliogenesis. The oviducts are removed from prepuberal or castrate monkeys which have received five days of estrogen treatment.
Examination of Membrane Bound 𝛄-Globulin
Authors: Picklesimer John B. , Robinson John P.
Published: June 2020

A few years ago a physiological role was proposed for the lymphoid system quite apart from its immunological function. It was proposed that specific 𝛄-globulins were elaborated which bind to complementary sites on cell membranes and that these macromolecules played a role in the structural and functional integrity of the cell. It was subsequently reported that certain fractions of 𝛄-globulin do indeed bind to the surface membranes of autologous erythrocytes and leukocytes in vitro as well as in situ. These results led to the present attempt to demonstrate the presence or absence of membrane bound 𝛄-globulin by. electron microscopy under conditions outlined by the above hypothesis.
Electron Microscopic Study of the Morphogenesis of Echovirus 23
Authors: Trant C. M. , Jamison R. M.
Published: June 2020

The cytopathology which accompanies the replication of Echovirus 23 in monkey kidney cells has been studied. Cells grown in monolayer cultures in glass bottles were infected with Echovirus 23 and incubated at 37°C. At varying intervals, cells were harvested for electron microscopy. Multiple embeddings of specimens at each interval post-infection were performed to confirm and extend the observations. It was noted that as the interval postinfection lengthened, individual infected cells rounded and detached from the surface of the monolayer. As the infectious cycle continued, virtually all cells in the bottle became detached. Accordingly, each infected bottle provided two specimens for electron microscopy; a) those free in the supernatent. fluid and b) those remaining on.the glass surface.
A Scanning Electron Microscopic Study of the Uriniferous Tubules
Authors: Andrews Peter M.
Published: June 2020

Although there have been a number of recent scanning electron microscopic reports on the renal glomerulus, the advantages of scanning electron microscopy have not yet been applied to a systematic study of the uriniferous tubules. In the present investigation, scanning electron microscopy was used to study the ultrastructural morphology of the proximal, distal, thin loop, and collecting tubules. Material for observation was taken from rat kidneys which were fixed by vascular perfusion, sectioned by either cutting or fracturing technigues, and critically point dried.

The brush border characterising proximal tubules is first detected on the luminal surface of Bowman's capsule adjacent to the urinary pole orifice. In this region one frequently finds irregular microvilli characterized by broad and flattened bases with occasional bulbous structures protruding from their surfaces.