bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of Scanning Electron Microscope Specimens from Liquid Dispersions of Solid Particulates
Authors: Walter Earl R.
Published: June 2020

A variety of techniques have been developed which do not materially alter the state of flocculation of solid particles dispersed in a liquid when that dispersion is prepared for transmission electron microscopy. However, similar techniques have not been developed to minimize the effect of surface tension on the flocculation of particles when dispersions are dried down on a support for scanning electron microscopy. The problem is often compounded by the larger sample size involved and the generally larger particles studied in the SEM. With today's emphasis on air and water polution, sewage treatment, etc., simple, rapid techniques of sample preparation to allow reliable particle size studies are becoming increasingly important.

When a liquid dispersion of solid particles is dried down on a substrate for SEM characterization, surface tension and thermal gradients in the evaporating liquid may materially alter the degree of flocculation and introduce severe particle size fractionation in different areas of the specimen.
Resolution-Limiting Effects in Electron Microscope Images
Authors: Anstis G. R. , O'Keefe M. A.
Published: June 2020

The resolution of a high-resolution lattice image is usually regarded as being set by the size of the objective aperture used in obtaining the image. However, experimental structure images (i.e. images obtained at optimum defocus) do not usually obtain the resolution one might expect merely from a consideration of the spatial frequencies of the beams contributing to the image. Structure images obtained by Iijima (1) (e.g. Fig. 4a), with an objective aperture admitting beams corresponding to a resolution of 3. 8Å at lOOkeV, show instead a resolution of 3. 8Å. This loss of resolution may be viewed as occurring due to the imposition of a virtual aperture by the resolution- limiting factors of chromatic aberration and incident electron beam convergence.
Information, Localization, and Damage in the Stim
Authors: Escovitz Wm. H. , Fox T. R. , Levi-Setti R.
Published: June 2020

We present an estimation and evaluation of cross sections relevant to the performance of the scanning transmission ion microscope (STIM). Figure 1 shows the relationship between the total elastic and inelastic cress sections (σe, σi) for protons and electrons at energies important to microscopy. Assuming equal collection efficiencies, the ratio σe/σi is a figure-of-merit for evaluating high resolution information obtainable for a given amount of radiation damage for different microscopes. The ratio σe/σjis calculated for carbon. Since there is no reliable calculation of σifor protons in the low energy region, we obtained an empirical estimate of σiby the following procedure. First, it was assumed that the ratio Ri of dE/dx for protons (experimental2) and dE/dx for electrons (theoretical3) is the same as the ratio of the respective σi:
Scanning Auger Electron Microscopy at 30 Nm Resolution
Authors: Venables J. A. , Janssen A. P. , Harland C. J. , Joyce B. A.
Published: June 2020

An HB50 FEG SEM with a specially designed conical final lens and UHV specimen chamber has been supplied by V.G. Microscopes Ltd., East Grinstead, U.K., to which we have fitted a CMA supplied by Varian Associates, Inc. The design of this microscope has been outlined elsewhere (1) but the geometry can be understood by reference to fig. 1. The CMA is bellows mounted so that it can be aligned with respect to the SEM beam, and retracted in other modes of operation. Auger signal detection is via a Brookdeal 9501 phase sensitive detector (PSD) system.

An input module for the SEM has been constructed to feed the PSD signal into the SEM display system, resulting in the following modes of Auger operation: (1) An energy scan uses the ‘spectrum’ mode of the microscope to drive the energy ramp of the CMA, resulting in a (dN/dE) Auger spectrum from a chosen point on the sample scanned between any two energy limits; (2) A line scan uses the ‘line’ mode of the microscope to display the Auger signal dN/dE for a given element (i.e. at a given E) from a chosen line on the sample.
A General Method for Spectrometer Design in the Scoff Approximation
Authors: Fields J. R.
Published: June 2020

The energy analysis of electrons scattered by a specimen in a scanning transmission electron microscope can improve contrast as well as aid in chemical identification. In so far as energy analysis is useful, one would like to be able to design a spectrometer which is tailored to his particular needs. In our own case, we require a spectrometer which will accept a parallel incident beam and which will focus the electrons in both the median and perpendicular planes. In addition, since we intend to follow the spectrometer by a detector array rather than a single energy selecting slit, we need as great a dispersion as possible. Therefore, we would like to follow our spectrometer by a magnifying lens. Consequently, the line along which electrons of varying energy are dispersed must be normal to the direction of the central ray at the spectrometer exit.
Thin Graphite Supporting Films for High Resolution Work
Authors: Iijima Sumio
Published: June 2020

Background noise arising from amorphous carbon supporting films is a crucial problem for high resolution CTEM work, particularly for biological materials. Many people have been trying to overcome this problem, for example, by use of sophisticated image analysis by computers, but without convincingly successful results so far. On the other hand, it is theoretically expected that if we use thin single crystal films the background noise can be completely eliminated. This has been attempted by a few workers (1,2) who used single crystals of BeO or graphite for observing very small metal particles or single atoms. Here we shall report a method of preparing very thin and clean single crystal films of graphite and their properties.

Preparation of thin graphite films. Firstly relatively thin graphite films were prepared by repeated cleavage of a graphite crystal between Scotch tapes. Small flakes of cleaved graphite crystal stuck on the tapes were separated in ethylene dichloride.
Economical Halftone Images from Digital Data Produced by a Stem
Authors: Zubin J. A. , Wiggins J. W.
Published: June 2020

The commercial availability of the electrostatic dot matrix line printer (l) provides a new method of halftone generation. In conventional commercial printing, shades of gray in pictures are reproduced by a halftone process. The halftone image is generated by a system of minute dots produced by a screen placed in the camera a short distance in front of a sensitized plate. Halftone printing screens have between 50 and 150 lines per inch. The electrostatic line printer has 200 nibs per inch and is capable of writing 2112 dots across an eleven inch wide piece of paper. Using 4 nibs or dots on 4 successive lines, one is able to generate the equivalent of a 50 line per inch printing screen. The nibs are seven mils in diameter and are located on five mil centers.
A New Type of Dislocation Reaction in the Ni2Alti Heusler Phase
Authors: Tzeng Wen-Shian , Strutt P. R.
Published: June 2020

The operative high temperature glide modes in Ni2AlTi have been studied and previously reported (1). The unit cell for this Heusler type structure phase is composed of eight CsCl type unit cells in which Ni atoms form one sublattice while Al and Ti atoms occupy ordered sites on the other sublattice. Electron microscope contrast analyses of dislocations in Ni2AlTi deformed in creep at 1000°C showed the predominant Burgers vector to be ao/2 <110>, where ao refers to the ao/2<110> Heusler unit cell. However, another type of dislocation was observed, this consisted of a pair of ao/2<110> dislocations coupled by a sublattice A.P.B. fault. Subsequent to this, dislocation pairs in the glide configuration have been observed, i.e. the dislocation Burgers vector lies in the fault plane. In what follows an example of such a dislocation pair and its interaction with ao/2<110> dislocations is presented.
Systematic Variation of Microstructure in Vapor-Deposited Ag Coatings on Cu Substrates: Studies of the Effect of Microstructure on Laser Damage Thresholds
Authors: Szilva W.A. , Murr L.E.
Published: June 2020

The attainment of high power density lasers is, in many respects, limited by the properties of windows and mirrors; and is therefore materials limited. Aside from microcracks, voids, and other structural features contributing to laser-induced degradation, there has been some indication that other microstructural phenomena such as the presence of crystal defects might also contribute. While the subject of short-pulse laser damage at the surfaces of both coated and uncoated dielectric materials has received considerable attention in recent years, little attention has been paid to the systematic evaluation of mirror surface and surface coating microstructure on laserinduced damage (or damage threshold). Although some preliminary work has been done on determining the relationship between the optical properties of metal films and departures from crystalline perfection of the films, no efforts have been made to determine the effects of metal coating microstructure on laser damage thresholds.
A Method for the Ultrastructural Localization of Sucrase
Authors: Lorenzsonn V. , Agresti H. , Olsen W. A.
Published: June 2020

Several studies have suggested that intestinal sucrase is located in 60 Å particles of microvillus membrane seen with negative staining. This localization has been questioned, however, because of a disparity between the disappearance of particles and enzyme activity from brush borders during 20 min. papain digestions. Ferritin labeled antibody to sucrase has also been used to study surface localization of the enzyme. We have devised an alternative method to allow us to study intracellular localization as well for study of the increased sucrase activity in diabetic mucosa. We modified the technique of Keston for ultrastructural use by replacing the chromagen with 3,3'-diaminobenzidine tetrahydrochloride (DAB).
Myoneural Junctions in Toadfish Swimbladder Muscle
Authors: Sidle James M.
Published: June 2020

Among vertebrate striated muscles studied to date, the toadfish swimbladder muscle is fastest with an average contraction time of 5 msec. The ultrastructure of this muscle has been examined, particularly with regard to the elaborate sarcoplasmic reticulum present, and a light-microscoplc study of the neuromuscular junctions has been performed. Motorneurons which innervate the swimbladder muscle were found to be electronically coupled by way of axo-somatic and dendro-somatic junctions.

The ultrastructure of the myoneural junctions in the Atlantic toadfish (Opsanus tau) was examined and the findings conform to those obtained from several other teleost twitch fibers.
Ultrastructural Changes in Friend Leukemia Cells After Dimethyl Sulfoxide (DMSO), Dimethyl Formamide (DMF), or 5-Bromo-2’-Dioxyuridine (BUdR) Treatment in Vitro
Authors: Sato T. , Harven E. de , Friend C. , Scher W. , Preisler H. D.
Published: June 2020

Murine Friend erythroleukemia cell (FLC) lines continuously produce Friend leukemia viruses as evidenced not only by electron microscope observation but also by the immunity against challenge with leukemogenic viruses given to susceptible mice with cell free filtrate of these cultures. When these cells were cultured in the presence of 2% DMSO, 3 major changes were observed: 1)increase of the number of budding viruses; 2)an enhanced cell differentiation along the erythoid pathway; and 3) the formation of cytoplasmic complex vacuolar structures containing many viruses (CVS).

We have been studying the effects on FLC of DMSO and DMF, as well as those of halogenated deoxyuridines which have been recently reported to increase the production of some murine RNA viruses, individually or in combinations.
Ultrastructural Evaluation of Ultimobranchial Thyroid Neoplasms in Bulls
Authors: Capen C. C. , Black H. E.
Published: June 2020

The recently characterized hormone calcitonin (thyrocalcitonin) is synthesized and secreted by parafollicular (C-) cells present in the mammalian thyroid gland. Parafollicular cells are derived embryo logical ly from primordia of neural crest origin that migrate into the ultimobranchial body during early embryonic development.

A syndrome of ultimobranchial thyroid neoplasms which shares many characteristics with medullary thyroid carcinoma in man occurs frequently in populations of old bulls. The development of these tumors may be related to a prolonged excessive intake of dietary calcium. Cows raised under similar environmental conditions do not develop ultimobranchial neoplasms. Affected bulls often have extensive skeletal disease and develop tumors in other endocrine organs.
Formation of Lamellar Bodies in Schwann Cell Cytoplasm Induced by Alcohol Injury
Authors: Sun C. N. , White H. J. , Flanigan S.
Published: June 2020

The presence of lamellar bodies in the Schwann cell has been encountered in several occasions. This presentation deals with lamellar bodies which occur in the Schwann cell of patients treated with 0.8 cc absolute ethanol intrathecal injection for relief of pain. Biopsies of nerve roots in the region of injection were taken from patients, 2 days and 5 days after ethanol treatment. Two days after alcohol injection, the myelin sheath of the axon in the Schwann cells was disrupted; in many cases, a complete destruction of the myelin system was seen (Fig. 1). By the 5th day after treatment, apparently less destruction was seen and we are led to assume that the damaged axons recovered through a process of remyelinization, although focal degeneration of the myelin sheath and lamellar bodies still remained.
Ozone-Induced Pulmonary Parenchymal Lesions in Rats
Authors: Plopper Charles G. , Dungworth Donald L. , Tyler Walter S.
Published: June 2020

Acute exposure to ozone in high concentrations produces histologically observable bronchiolar epithelial necrosis and pulmonary edema in the lungs of rats and other mammals. In this study, adult rats were exposed to 3 ppm ozone for 4 hours and sacrificed either within 20 minutes after exposure or 12 hours later. The lungs were fixed via the trachea with 2.5% glutaraldehyde. Tissue from specific regions of the acinus were chosen from large epon-araldite embedded blocks by a modification of the method of Grimley. Regular trapezoids were cut from 30µ sections with a # 11 scalpel blade and cemented on to blank epon blocks from BEEM capsules. In addition, arithmetic mean thickness of the blood-air pathway was evaluated morphometrically on randomly selected 1 mm cubes.
Cytochrome P-450 and Hydroxylating Activity of Microsomes from Fetal Gonads of the HorseEquus caballus
Authors: González-Angulo A. , Martínez-Zedillo G. , Hernández-Jáuregui P.
Published: June 2020

Cytochrome P-450 has been shown to participate as a terminal oxidase in mixed-function oxidations in mammalian liver. Cytochrome P-450 has also been detected in human liver and this organ has been regarded as the tissue with the highest hydroxylating activity. Isolated reports describing determination of cytochrome P-450 in developing rat liver tissue has revealed minor quantities of this hemoprotein. Determinations of cytochrome P-450 in testes of adult rats yielded low levels of this enzyme complex. On the other hand, ultrastructural studies on the morphology of fetal gonads both male and female, ofE. caballushave revealed that the increase in size of these gonads is due to a proliferation of interstitial cells rich in smooth endoplasmic reticulum with clear evidence of continuous neoformation of this cell organelle.
The Mode of Action of Surface Lysosomes of Entamoeba histolytica in Human Infections
Authors: Miller J. H. , Gilman R. H. , Villarejos V.M.
Published: June 2020

Biopsies were obtained from lesions in the rectal mucosa of 23 Orang Asli (aborigine) patients with amebic dysentary in order to study the morphology of Entamoeba histolytica trophozoites during active colonization of the intestinal mucosa. Liver tissue was also obtained in Costa Rica from a case of amebic liver abscess at autopsy. Biopsies were immediately fixed 3-8 hours in cold gluteraldehyde buffered with cacodylate. After fixation, specimens were washed, stored in buffer, and sent to New Orleans where the standard post-osmication, acid-phosphatase treatment, and Araldite embedding were accomplished. Tissue from Costa Rica was handled similarly. Sections were cut with diamond knives and examined at 50 KV in a Hitachii HU-11A.
Surface Coat of Entamoeba histolytica Trophozoites. - Ultrastructural Cytochemical Study
Authors: Feria-Velasco Alfredo , Treviño Norberto , Chávez Isabel Ruiz de
Published: June 2020

The surface or extraneous coat has been investigated in some free-living amoeba such as A. proteus and Chaos chaos using ruthenium dyes and alcian blue. Although the surface coat of E. histolytica trophozoites can be visualized with routine techniques for electron microscopy, its details and various elements appear ill-defined (Fig. 1). By using lanthanum staining after aldehyde fixation with alcian blue according to Shea's method, or ruthenium red during postfixation with OsO4 we were able to observe the extraneous coat of HK-9:NIH strain trophozoites of E. histolytica cultured in axenic conditions. Some trophozoites were incubated with neuraminidase at pH 5.0 for 60 minutes at 37°C before staining with alcian blue and lanthanum in the fixatives. The samples in all experiments were dehydrated and embedded in araldite and the sections were observed unstained.
Scanning and Transmission Electron Microscopy of Isolated Cells of Hydra littoralis
Authors: Westfall Jane A. , Enos Paul D.
Published: June 2020

Using scanning and transmission electron microscopy (SEM and TEM), we observed batteries of 20-30 nematocytes, cnidoblasts, sensory cells, and other neurons invaginated within epitheliomuscular cells ofHydra. In an attempt to determine how the cells were structurally interrelated, we isolated cells ofHydra littoralisfor further study by SEM and TEM.

To isolate cells, 30Hydra littoraliswere placed for 30 minutes in a P19 culture medium modified by omitting calcium and magnesium ions, adding 20% sucrose and stabilizing at pH 7.2 with sodium phosphate, then pipetted gently to free the epithelial cells from the mesoglea. Glutaraldehyde was added to make a 5% solution and the cells were fixed 1 hour at 0-4°C, centrifuged 10 minutes at 1000 X g, resuspended in cacodylate buffer twice, and placed 2 hours in 4% osmium tetroxide at 0-4°C.
Control of Secretory Production in the Isopod Hepatopancreas
Authors: Roberts John W. , Witkus E. R.
Published: June 2020

The isopod hepatopancreas, as exemplified byOniscus ascellus. is comprised of four blind-ending diverticula. The regenerative cells at the tip of each diverticula differentiate into either club-shaped B-cells, which serve a secretory function, or into conoid S-cells, which serve in the absorption and storage of nutrients.

The glandular B-cells begin producing secretory material with the development of rough endoplasmic reticulum during their process of maturation from the undifferentiated regenerative cells. Cytochemical and morphological data indicate that the hepatopancreas sequentially produces two types of secretory material within the large club-shaped cells. The production of the carbohydrate-like secretory product in immature cells seems to be phased out as the production of the osmiophilic secretion was phased in as the cell matured.
Electron Microscope Study of the Closed Circulatory System of Nereis
Authors: Nakao Taisuke
Published: June 2020

According to the architecture of the walls, blood vessels of Nereis can be classified into three groups: I) interstitial type; 2) mesothelial type; 3) epidermal or respiratory type.

Interstitial type: It is represented by the intestinal vessels which are located in the interstitial connective tissue of the gut wall between the intestinal epithelium and the muscular strata which are assumed to be derived from the mesothelium. The walls of these vessels are made of a fibrillar, collagenous, connective tissue which directly limits the contour and extension of the vascular lumen. There is no true endothelium but amoebocytes can be found scattered against the wall. On the coeliac side of the vessels, this tissue is limited by the basal lamina which is backed by the muscular strata and the mesothelial cell layer, while it is limited, on the other side, by the basal lamina of the intestinal epithelium.
Genome Sizes of Chloroplast and Mitochondrial DNA's in Higher Plants
Authors: Kolodner Richard , Tewari K.K.
Published: June 2020

Chloroplast (ct-) and mitochondrial (mt-) DNA's from pea, spinach, bean, and lettuce leaves have been studied for their molecular size and conformation. The ct-DNA's from these plants were found to band at a density of 1.698 ± 0.001 g/cm3 and denatured with a Tm of 84° ± 0.5°C. The corresponding mt-DNA's had a buoyant density of 1.706 ± 0.001 g/cm3 and denatured with a Tm of 88° ± 0.5°C. Both ct- and mt-DNA from these plants were found to have a homogeneous melting pattern. The sheared and denatured ctand mt-DNA's from these plants were found to renature as a single kinetic class with no indication of repeating sequences. The molecular weight of the ct-DNA from the higher plants studied has been found to be 95 ± 5 x 106 by renaturation rates assuming a value of 106 x 106 for T4 DNA.
Replication of Bacteriophage 186 DNA
Authors: Chattoraj Dhruba K. , Inman Ross B.
Published: June 2020

Electron microscopy of replicating intermediates has been quite useful in understanding the mechanism of DNA replication in DNA molecules of bacteriophage, mitochondria and plasmids. The use of partial denaturation mapping has made the tool more powerful by providing a frame of reference by which the position of the replicating forks in bacteriophage DNA can be determined on the circular replicating molecules. This provided an easy means to find the origin and direction of replication in λ and P2 phage DNA molecules. DNA of temperate E. coli phage 186 was found to have an unique denaturation map and encouraged us to look into its mode of replication.
Electron Microscope Observations on DNA and Chromatin Fibres of Hydra Vulgaris and Ephydatia Meyeni
Authors: Mookerjee Anjali
Published: June 2020

The present paper reports the observations made on DNA and chromatin material obtained from Hydra vulgaris (raised in laboratory culture) and a fresh water sponge Ephydatia meyeni. Both samples were prepared following Marmur's method, with slight modifications. For the chromatin fibres, samples were used just after the cell lysis stage without any shaking or further purification procedures. The specimens for electron microscopy were prepared by the protein monolayer technique.

The diameter of rotary shadowed purified DNA samples from H. vulgaris and E. meyeni was 60-80 A and the length of the Fibres varied between 5-18 /u (Fig. 1), and 5-10/u respectively.
The Nucleus in the Spores of Rhinosporangium seeberi
Authors: Mishra R. K. , Anand K. , Kacker S. K. , Falor Wm. H.
Published: June 2020

Rhinosporidiosis is a disease occurring usually in the tropics and is characterized by the production of nasal polyps supposedly caused by a fungus, Rhinosporangium seeberi, which was claimed after light microscopic studies to proliferate by “amitotic” division of the nucleus. The organism was studied electron microscopically and the spores were found to be bound by a non-collagenous wall enclosing a variety of vesicles, some containing smooth amorphous material, others coiled threads, and still others dark granules. Typically mitochondria, endoplasmic tubules, Golgi, and a membrane-bound nucleus were not seen although a few rudimentary membrane-bound spaces are present. These features as well as failure to culture the organism cast doubts about its taxonomic position, and it seemed the organism was essentially some nucleic acid complex organizing mucopolysaccharides in subepithelial zones in the nasal mucous membrane.
Ultrastructural Similarities Between Adrenal Medullary and Paraganglion Cells
Authors: Mascorro Joe A. , Yates Robert D.
Published: June 2020

The fine structural characteristics of adrenal medullary chromaffin cells to include their cytoplasmic detail, vascularity, innervation and catecholamine (CAM) content have been well studied. However, not until recently has this same interest been applied to similar chromaffin cells classified, as paraganglion cells and located in areas away from the adrenal medulla. The present results involving morphological comparisons between paraganglion (PC) and adrenal medullary cells (AMC) indicate that these cellular elements are essentially identical.

Syrian hamsters were perfused with 3% glutaraldehyde in 0.1 M phosphate buffer and post fixed, in 1% osmic acid. A retroperitoneal tissue block containing the coeliac and superior mesenteric artery trunks and abdominal aorta was excised, divided into slices and flat embedded in Epon 812.
Subplasmalemmal Microfilaments and Microtubules in Cultivated Macrophages
Authors: Reaven E.P. , Axline S.G.
Published: June 2020

Recent studies suggest that contractile microfilaments and/or microtubules may mediate cell movement and intracellular transport of cytoplasmic constituents. Current studies of control, phagocytizing and cytochalasin B (CB) treated macrophages provide evidence that membrane translocation required for endocytosis may involve similar mechanisms.

Mouse peritoneal macrophages, cultivated for 48 hours, were fixed and embedded directly on glass coverslips to preserve the original orientation of the monolayers. Analysis of serial thin sections cut parallel to the plane of glass attachment disclosed a number of features of the cells not previously described.

1) A loose, delicate, continuous network of 40-50 Å microfilaments extending from the inner surface of the plasmalemma to a depth of 500-600 Å were found in all regions of the cell (Fig. 1). In areas of normal pseudopodal folding or retraction, the network was thickened and of increased density. The filaments of this network were insensitive to CB treatment (5-10 μg/ml).
Alcoholic Hyalin and Cytoplasmic Filaments in Biliary Epithelial Cells
Authors: Minick Odell T. , Yokoo Hidejiro , Batti Fawzia
Published: June 2020

Biliary epithelial cells have previously been shown to be a site of alcoholic hyalin (AH) deposition. To learn more of the nature and pathogenesis of this inclusion, the fine structure of proliferating biliary ductules was studied in 20 patients with alcoholic liver disease. The changes were compared with those observed in hepatocytes containing alcoholic hyalin.

The ductular cells often displayed dilated cisternae of rough endoplasmic reticulum, prominent Golgi complexes, and an increase in lysosomes. Mitochondria were larger, more numerous and contained more cristae than those usually seen in ductules (Fig. 1). Double nuclei were common. Dense, compact cells, probably degenerative in nature, were often noted.
Particle Counting of Partially Purified RNA Tumor Viruses by a Thin Sectioning Technique
Authors: Miller M. F. , Allen P. T. , Bowen J. M. , Dmochowski L. , Hixson D. C. , Williams W. C.
Published: June 2020

Most of the available methods for counting virus particles in the electron microscope require the sedimentation or spreading of particles on an electron transparent film and their visualization by negative staining or replica techniques. Two problems are encountered in these methods. Uniform distribution of particles on support films is difficult due to surface tension effects. Unless the virus preparation is highly purified, recognition of virus particles among cell debris may be difficult. This can be largely eliminated by the use of thin sections. Counting virus particles in thin sectioned pellets requires large quantities of purified virus. Membrane filters serve as suitable substrate for pelleted virus particles which can be examined in thin sections.
St. Louis encephalitis virus infection of a mosquito vector
Authors: Whitfield Sylvia G. , Murphy Frederick A. , Daniel Sudia W.
Published: June 2020

The course of arbovirus infections in the arthropods necessary for their transmission in nature has been studied extensively, but in only a few instances at the ultrastructural level. In the present study a model system was established for the infection of Culex mosquitoes with St. Louis encephalitis (SLE) virus (arbovirus group B ), the most important mosquito-bome disease in the United States. Results were compared with those of a previous study of Eastern equine encephalitis virus (arbovirus group A) in Aedes mosquitoes (this Proceedings, 1969, pp. 378-379) since differences in sites of maturation in mammalian cells have been found between the two groups.

Culex pipiens mosquitoes were infected by feeding upon suckling mice infected with SLE virus (plasma viremia titer 105.4 SMLD50/ml). Mosquitoes were then held at 27°C; they were tested for capacity to transmit virus via bite, and specimens of salivary glands and other organs were collected at 18 intervals during 32 days.
The Nature of Polyhedral Inclusion Bodies of Thiobacillus Neopolitanus
Authors: Ball F. L. , Shively J. M. , Breillatt J. P. , Caton J. E. , Brownt D. H.
Published: June 2020

Polyhedral inclusion bodies (alpha particles) of unknown function have been observed previously in T. neopolitanus by electron microscopy of thin sections. Partial characterization of these bodies has been accomplished by means of rate-zonal centrifugation. The cells were broken by a French pressure cell, treated with deoxyribonuclease prior to centrifugation.

Figure 1 is a thin section of T. neopolitanus showing bacteria with varying numbers of alpha particles.

Initial attempts were made to isolate the intact alpha particles by ratezonal and isopycnic methods in both swinging bucket and zonal rotors. Nevertheless, the alpha particles were usually contaminated with membrane fragments and other cellular material as well as inner components (alpha particles) from partially ruptured alpha particles, as shown in Fig. 2.
An Electron Microscopic Study of the Human Gastric Epithelia with Special Reference to the Ultrastructural Changes of the Parietal cells Induced by “Histalog“
Authors: Saito Hiroshi , Asano Goro , Aihara Kaoru , Fukushi Katsunari , Yoshida Minoru , Kimura Ken
Published: June 2020

This is to communicate the ultrastructural changes of the parietal cells of the human gastric mucosa in “Histalog” stimulation.

Gastro-endoscopic biopsy specimens from 48 adult patients suffering from various gastritic conditions are studied. The patients are roughly divided into two groups. The first group consists of the control study. In essentially intact gastric mucosa (hyperacidic) cases, the “Histolog” 50mg had been injected intramuscularly to the subjects and chronologically endoscopic biopsy study had been achieved at 5, 10, 15, 20, 30, and 60 minutes respectively. The second group consists of the study with advanced atrophic gastritis (anacidity) and similar manipulation has been attemped. The obtained specimens were quickly fixed in 2.5% glutaraldehyde, postosmificated, and dehydrated in graded alcohols and embedded in Epon 812. Sections were cut and observed with the Hitachi 11U-B electron microscope with 50kv or 75kv accelerating voltages.
Electron Microscopic Characterization and Quantitation of Air Borne Particulate Matter with Special Emphasis on Asbestos
Authors: Mueller Peter K. , Smith Glenn R. , Carpenter Leslie M , Stanley Ronald L.
Published: June 2020

At the present time the primary objective of the electron microscopy group of the Air and Industrial Hygiene Laboratory is the development of a method suitable for use in establishing an air quality standard for asbestos in ambient air and for use in its surveillance. The main concept and thrust of our approach for the development of this method is to obtain a true picture of fiber occurrence as a function of particle size and asbestos type utilizing light and electron microscopy.

We have now available an electron micrographic atlas of all asbestos types including selected area diffraction patterns and examples of fibers isolated from air samples. Several alternative approaches for measuring asbestos in ambient air have been developed and/or evaluated. Our experiences in this regard will be described. The most promising method involves: 1) taking air samples on cellulose ester membrane filters with a nominal pore size of 0.8 micron; 2) ashing in a low temperature oxygen plasma for several hours;
Transformational Approaches to Scanning Electron Microscopy
Authors: Hayes Thomas L.
Published: June 2020

Scanning electron microscopy has generally assumed the traditional attitude towards transformation of the specimen or image: avoid any changes in favor of faithfully maintaining all characteristics of the specimen. In spite of the difficulty of defining the artifact free state, the goal of fidelity has served well as the basic rule for both conventional and scanning electron microscope investigation and will continue to be the most desirable approach in the future. Occasionally, however, it may be useful to consider an alternative path to gaining knowledge about the specimen. Instead of attempting to eliminate all artifact, we might purposely introduce controlled transformations. Thus, rather than being completely single-minded in the very difficult pursuit of absolute fidelity, we may find an alternative solution in a thorough understanding of the artifacts that we have purposely introduced.
Applications of Ultramicrotomy in the Electron Microscopy of Clay Minerals
Authors: Brown John L.
Published: June 2020

Large flakes of a specimen muscovite from Amelia, Virginia were broken apart in water with an Omni-Mixer, and the fraction between 0.2 and 2μ was separated by centrifugation. An oriented sample of the fraction gave a sharp 10Å X-ray diffraction peak as well as integral higher orders of this (001) reflection. A portion of the same sample was deposited from water suspension onto the surface of an Araldite slab. Additional resin was added and cured to form a sandwich. Sections were cut perpendicular to the sediment plane and examined in a Philips Em-200 microscope at 100KV. Figure 1 shows a lattice image of the (001) planes with indications of stacking faults and growth-step planes. Another portion of the muscovite fraction was subjected to repeated treatments in an autoclave with 0.1N BaCl2 until 76% of the potassium was replaced by barium. The resultant sample gave a 12.1Å (001) X-ray reflection or 9.9Å if dried over P2O5.
Scanning Microscopy of Human Intestinal Explants in Organ Culture
Authors: Wetzel Bruce , Buscho Robert , Dolin Raphael
Published: June 2020

It has been reported that explants of human fetal intestine can be maintained in culture for up to 21 days in a viable condition and that these organ cultures support the growth of a variety of known viral agents responsible for enteric disease. Scanning electron microscopy (SEM) has been undertaken on several series of these explants to determine their appearance under routine culture conditions.

Fresh specimens of jejunum obtained from normal human fetuses were washed, dissected into l-4mm pieces, and cultured in modified Leibowitz L-15 medium at 34° C as previously described. Serial specimens were fixed each day in 3% glutaraldehyde for 90 minutes at room temperature, rinsed, dehydrated, and dried by the CO2 critical point method in a Denton DCP-1 device. Specimens were attached to aluminum stubs with 3M transfer tape No. 465, and one sample on each stub was carefully rolled along the adhesive such that villi were broken off to expose their interiors.
SEM, STEM, and HVTEM Examinations of Aluminum Thin Films Produced by Glass Knife Microtomy
Authors: Temple Black J.
Published: June 2020

One of the more interesting aspects of the microtomy process lies in its application to the cutting of metals. It has been found that many softer metals can be microtomed with a glass knife as well as with the traditional diamond knife. These thin films can be used to study the deformation mechanism and defect physics of the cutting process. The microtomy process is actually orthogonal cutting (2 force mechanics) on a refined scale. Metal cutting is a unique mode of plastic deformation in that it is a large strain, high strain rate process, which produces a characteristic, fundamental deformation. Chips produced by thin film microtomy methods can be examined directly in the various electron microscopes without any subsequent thinning operations which may disturb the deformation structure. In addition, it is possible to examine the same areas of the specimen for both external morphology features (via SEM imagery) and internal defect arrangements (via STEM and HVTEM imagery) and thus one can observe directly how these structures are related.
Failure Analysis With the Scanning Electron Microscope
Authors: Devaney John R.
Published: June 2020

Occasionally in history, an event may occur which has a profound influence on a technology. Such an event occurred when the scanning electron microscope became commercially available to industry in the mid 60's. Semiconductors were being increasingly used in high-reliability space and military applications both because of their small volume but, also, because of their inherent reliability. However, they did fail, both early in life and sometimes in middle or old age. Why they failed and how to prevent failure or prolong “useful life” was a worry which resulted in a blossoming of sophisticated failure analysis laboratories across the country. By 1966, the ability to build small structure integrated circuits was forging well ahead of techniques available to dissect and analyze these same failures. The arrival of the scanning electron microscope gave these analysts a new insight into failure mechanisms.
Hole Formation in Gold Films
Authors: Vook R. W. , Cook R. , Ziemer R.
Published: June 2020

During recent experiments on Au films, a qualitative correlation between hole formation and deposition rate was observed. These early studies were concerned with films 80 to 1000A thick deposited on glass at -185°C and annealed at 170°C. In the present studies this earlier work was made quantitative. Deposition rates varying between 5 and 700 A/min were used. The effects of deposition rate on hole density for two films 300 and 700A thick were investigated.

Au was evaporated from an outgassed W filament located 10 cm from a glass microscope slide substrate and a quartz crystal film thickness monitor. A shutter separating the filament from the substrate and monitor made it possible to obtain a constant evaporation rate before initiating deposition. The pressure was reduced to less than 1 x 10-6 torr prior to cooling the substrate with liquid nitrogen. The substrate was cooled in 15 minutes during which the pressure continued to drop to the mid 10-7 torr range, where deposition was begun.
The Structure of Graphite Fibers Utilized in Field Ionization
Authors: Bowles C.Q. , Stillie G.D.
Published: June 2020

Field ionization mass spectrometry has become an increasingly useful analytical tool because of the absence of mass spectra cracking patterns normally associated with electron impact methods. However a rather trouble some experimental difficulty has been the development of an ionization source with ionization efficiency sufficient to produce detectable signals of trace components.

A graphite filament ionizer was recently developed at our laboratory and consists of a graphite whisker mounted taut between two tungsten posts. The exposed length of filament and its diameter are nominally 8 mm and 10-3 mm (1 micron) respectively. Ion yields of 10-11 amp at 10-6 torr (10-5 amp/torr) with ion energies of 6-7 Kev are readily obtainable. The filaments have also been used for field emission and Cox has used the Fowler-Nordheim equation modified for cylinderical geometry to obtain an estimated emitter diameter of 40 Å from his experimental data.
Displaced Aperture Dark Field Images by an Aberration Correction
Authors: Shirota K. , Yamamoto T. , Yanaka T. , Vingsbo O.
Published: June 2020

In displaced aperture dark field microscopy, the direction of the incident electron beam with respect to the specimen is maintained unaltered between bright field and dark field images, unlike the case of usual high resolution dark field microscopy by tilted illumination. The displaced aperture technique, however, gives a strong dark field image deterioration due to field aberrations. These are prounouncedly large since the deviation of the orbits of the imaging electrons from the optical axis is very large in this case. In the present paper, the improvement of the image quality by aberration correction is discussed.

1. The chromatic field aberration is composed of components mainly from the objective and intermediate lenses. It can be corrected by changing the electron orbit by means of a beam deflector, introduced in the image plane of the objective lens.
The Effect of Stress Upon the Precipitation of Coherent, Tetpagonally-Distorted Particles
Authors: Oblak J. M. , Paulonis D. F. , Duvall D. S.
Published: June 2020

The change in energy as a result of interaction between an applied stress and the transformation strain associated with a precipitate particle or inclusion of volume V has been given by Eshelby as where summation over repeated indices is implied. The example that we turn our attention to is the precipitation in a nickel alloy of coherent, tetragonally-distorted DO22 particles of composition Ni3Nb. This precipitate is coplanar with the fcc matrix and its crystallographic coordinates are the coordinates of principle strain, and . The particles form as discs on the ﹛100﹜ fcc planes normal to their axis of major strain, thus three variants are possible. As shown in Fig. 1, under normal aging conditions nearly equivalent amounts of the three variants are observed. The diffraction pattern included in Fig. 1 has been indexed with respect to the fcc matrix.
Photographic Equidensitometry of High Voltage Electron Images of Thick Noncrystalline Materials
Authors: Kobayashi Keinosuke
Published: June 2020

Equidensitometry as developed by E. Lau and W. Krug has been little used in the analysis of ordinary electron photomicrographs, yet its application to the high voltage electron images proves merits of this procedure. Proper sets (families) of equidensities as shown in the next page are able to reveal the contour map of mass thickness distribution in thick noncrystalline specimens. The change in density of the electron micrograph is directly related to the mass thickness of corresponding area in the specimen, because of the linear response of photographic emulsions to electrons and the logarithmic relation between electron opacity and mass thickness of amorphous object.

This linearity is verified by equidensitometry of a spherical solid object as shown in Fig. 1a. The object is a large (1 μ) homogeneous particle of polystyrene. Fig. 1b is a composite print of three equidensities of the 1st order prepared from Fig. 1a.
Electron Microscope Image Intensification and Specimen Exposure
Authors: Heinemann Klaus , Poppa Helmut
Published: June 2020

The efficiency of electron microscope image intensification (EMII) systems is often represented in terms of signal-to-noise ratio as a function of current density in the final microscope image plane. Such a characteristic is one way of evaluating the sensitivity of an EMII-system. It determines the intensification necessary to raise the signals of individual electrons well above the equipment noise level of the intensifier/display chain.

This approach to the problem of EMU may lead to misinterpretations since it does not consider the spatial resolution in the specimen. Usually, the spatial resolution of the EMII-chain is considerably inferior to the resolution of conventional photographic material. In internal photography one can, therefore, normally work with considerably lower electron optical magnifications than with an image intensifier system to resolve specimen details of the same dimensions.
Phase Contrast Enhancement by Single Sideband Modulation Transfer
Authors: Andersen Willem H.J.
Published: June 2020

Through-focal series of an empty carbon film with the corresponding optical diffractograms illustrate beautifully the contrast transfer theory of the electron microscope. This theory has gained great popularity among the electron microscope designers because it presents a means of obtaining an image quality figure for the instrument independent of the object, by using the contrast transfer function. Present objective lenses are nearly perfect in the sense that they perform close to the theoretical expectations. Paradoxically, this presents a serious problem for the biological electron microscopist who wants a faithful image of his sample at high magnification.

Biological E.M. samples are weak phase objects and consequently the E.M. is in principle not able to image the object with any contrast. Due to spherical aberration and defocussing, details < 10 Å are transferred, but the oscillating nature of the transfer function causes image interpretation problems. Staining of the object to obtain contrast is very unsatisfactory and methods have been sought to image phase structures from 5 Å upward with enhanced contrast.
Technique For Examining the Structure of Sputtered MoS2 Lubrication Films by Ion Erosion and Transmission Electron Microscopy
Authors: Shaw G. G. , Lavik M. T.
Published: June 2020

Sputtered MoS2 films have exhibited good friction and wear characteristics; and to reveal the morphology and crystal structure of the rather thick films, the following methods were used.

MoS2 was sputtered onto mechanically polished 1/8 in. thick 1100 aluminum blocks to a thickness of approximately 2 microns. The temperature of the blocks during sputtering was held at around 200°C by water cooling the sample holder. These conditions have yielded films of good lubrication properties. The sputtered surface was then coated with a heavy film of formvar and when dry, was scored into 1/8 in. squares and the squares floated off with a 4% solution of HgCl2 and then thoroughly washed in water. Since we wanted to examine the metal MoS2 interface, the center of the film, and the free surface; ion milling was chosen as a means of thinning to electron transmission thickness.
Development of a Rapid Survey Method of Sampling and Analysis for Asbestos in Ambient Air
Authors: Heffelfinger R. E. , Melton C. W. , Kiefer D. L. , Henry W. M. , Thompson R. J.
Published: June 2020

A methodology has been developed and demonstrated which is capable of determining total amounts of asbestos fibers and fibrils in air ranging from as low as fractional nanograms per cubic meter (ng/m3) of air to several micrograms/m3. The method involves the collection of samples on an absolute filter and provides an unequivocal identification and quantification of the total asbestos contents including fibrils in the collected samples.

The developed method depends on the trituration under controlled conditions to reduce the fibers to fibrils, separation of the asbestos fibrils from other collected air particulates (beneficiation), and the use of transmission microscopy for identification and quantification. Its validity has been tested by comparative analyses by neutron activation techniques. It can supply the data needed to set emissions criteria and to serve as a basis for assessing the potential hazard for asbestos pollution to the populace.