bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Ultrastructure of Gram (−) Bacteria: II. Determination of the Gram Reaction in Antartic Soil Bacteria by Electron Microscopy
Authors: Uydess I. L. , Vishniac Wolf 
Published: June 2020

A modified negative staining technique (“OTPT”) has been described in the study of the surface topography of bacteria. This technique is useful in the rapid and accurate identification and discrimination of the Gram reaction of unknown bacteria under circumstances unfavorable to the direct application of the Gram stain. Cells of a particular genus exhibit the same basic topographical features independent of cell age, culture conditions or other cellular parameters.Several pure cultures of unclassified bacteria isolated from Antarctic soils were prepared by the OTPT staining method. Although initial attempts employing the Gram stain were often inconclusive, this technique allowed a positive identification of all samples. Two organisms were chosen for more detailed study.
Unique Features of a High Resolution Scanning Transmission Electron Microscope
Authors: Wiggins J. W. , Beer M. , Woodruff D. C. , Zubin J. A. 
Published: June 2020

A high resolution scanning transmission electron microscope has been constructed and is operating. The initial task of this instrument is to attempt the sequencing of DNA by heavy-atom specific staining. It is also suitable for many other biological investigations requiring high resolution, low contamination and minimum radiation damage.The basic optical parameters are: 20 to 100 KV acceleration potential, objective lens focal length of 1.0 mm. with Cs = 0.7 mm., and two additional lenses designated as condensor and diffraction lenses. The purpose of the condensor lens is to provide a parallel beam incident to the objective, and the diffraction lens produces an image of the back focal plane of the objective in the plane of an annular detector.
Application of TEM to Deformation, Wear, and Fracture of Ceramics
Authors: Hockey B. J. 
Published: June 2020

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.
On Some Testing Specimens for High Resolution SEM
Authors: Lin P. S. D. 
Published: June 2020

In assessing the resolving power of a high resolution scanning electron microscope using field emission tip (Hitachi HFS-2), two types of specimens were found to be of value.Fig. 1a, 1b are two successive exposures of some bright spots found on some thin carbon films. These carbon films were originally prepared for work in a high resolution scanning transmission electron microscope. Spots similar in size and distribution have been detected on micrographs taken in that microscope (Fig. 2).
Methionine-Specific Staining of Collagen
Authors: Kuhn E.M. , Marenus K.D. , Beer M. 
Published: June 2020

Fibers composed of different types of collagen cannot be differentiated by conventional electron microscopic stains. We are developing staining procedures aimed at identifying collagen fibers of different types.Pt(Gly-L-Met)Cl binds specifically to sulfur-containing amino acids. Different collagens have methionine (met) residues at somewhat different positions. A good correspondence has been reported between known met positions and Pt(GLM) bands in rat Type I SLS (collagen aggregates in which molecules lie adjacent to each other in exact register). We have confirmed this relationship in Type III collagen SLS (Fig. 1).
The Influence of Inflation Level on the Ultrastructure of Pleura
Authors: O'Sullivan Michael F. , Corn Carolyn , Dodson Ronald F. , Hurst George A. 
Published: June 2020

The pleura is a membranous coating which lines the pleural cavity. An extension of this lining forms a closely apposed continuous sheath from the apex to the base of the lungs and constitutes the visceral pleura.While certain pathological changes such as thickening, rare-asbestos related tumors (mesotheliomas), and other pathomorphological features are recognized with regard to pleural response, a comparison of pleura from inflated and deflated lungs has not been described. These features must be established if the true early pathological responses are to be differentiated from artificially induced changes.
Digitally Controlled Multipoint STEM-EDX Microanalysis
Authors: Boyes E. D. 
Published: June 2020

Spatially resolved microchemical analysis of thin specimens by STEM-EDX can with advantage be performed using a series of quantitative analyses at a number of selected discrete points in a digitally controlled array.The conventional line traces in X-ray peak intensity are not necessarily a good indication of elemental distributions. Substantial errors can occur as a result of the need for spectrum processing, X-ray corrections and in the case of thin specimens due to variations in specimen thickness which may be associated with differential polishing of regions of different chemical composition during sample preparation. In some circumstances ratio line scanning1 may be an improvement.
The Cytological Basis for Cortisone Action on Rat Liver Cells
Authors: Friedberg Jonathan E. , Cardell Robert R. 
Published: June 2020

The objective of this investigation is to provide morphological information on the action of a hormone. We have chosen to study the action of cortisone on the rat liver because it is established that this steroid has a stimulatory effect on the synthesis of the gluconeogenic enzymes. The glucocorticoids (including cortisone) are secreted by the adrenal cortex; hence, adrenalectomy renders the animal deficient in these hormones and impairs carbohydrate metabolism in the hepatocyte by reducing gluconeogenesis. Cortisone injection into an adrenalectomized rat increases the capacity of this cell to produce glucose from non-carbohydrate precursors. We have studied with the electron microscope liver cells from normal, adrenalectomized, and adrenalectomized, cortisone-treated rats. All rats were allowed free access to saline solution and were fasted for 15 hours before sacrifice.The liver cell of the adrenalectomized rat (Fig. 1) presents several striking alterations as compared with the normal hepatocyte. A conspicuous difference is the almost complete absence of particulate glycogen after the animal has been fasted for 15 hours. More remarkable is the very sparse development of the smooth endoplasmic reticulum (SER) in these glycogen-depleted cells.
Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.
Authors: Bayer Manfred E. 
Published: June 2020

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.
Freeze Etching With Radiant Energy in a Simple Cold Block Device
Authors: McAlear James H. , Kreutziger G. Oscar 
Published: June 2020

Freeze etching of biological samples was developed by Steere, refined by Moor et al, and simplified by Bullivant. Moor's device permitted the rapid freezing of specimens, precision fracturing in vacuo and etching of the fractured surface by raising the specimen temperature. Bullivant’s simplification featured cleaving the frozen specimen outside of the vacum under liquid N and then protecting the cleaved surface in a cold block with a tight fitting lid until he was ready to shadow and replicate. He could not etch with this device and much detail in the specimen was lost.The present device uses the cold block and lid concept. The lid has tunnels through which shadowing and replication of the specimen surface occurs. This lid, however, is free to swing bringing a knife on its lower surface through the specimen which is affixed to a pedestal on the upper surface of the base (Figures 1, 2 & 5). After cleaving the specimen the lid passes to its clockwise stop bringing the tunnels in the lid in line with the electrodes and the specimen surface.
Pathological Protein Biosynthesis in the Vestibular Nucleus and Other Neurons of Rat Brain During Kanamycine Administration
Authors: Bak I. J. 
Published: June 2020

An electron microscopic study was made on cells of the vestibular nucleus and other neurons of rat brain during kanamycine and streptomycine treatment.15 healthy male rats with an average body weight of 250-300 g were used throughout the whole experiments. The animals were devided into 3 groups and were given intramuscular injections of 200mg/kg of streptomycine and 400mg/kg of kanamycine respectively) the 3rd group was used as control. After repeated injections over a period of 5 days, the brains were removed and the vestibular nucleus, substantia nigra and pineal gland were harvested and fixed in 6% glutaraldehyde, buffered with phosphate at pH 7.4 prior to OsO4 fixation.The tissues were dehydrated in a series of graded alcohol and embedded in Epon 812, sectioned with LKB ultratome, stained in both uranyl acetate and lead citrate and studied in a Siemens Elmiskop 1A.
The Chromatoid Body in Syrian Hamster Spermatocytes: Its Morphology and Distinctive Characteristics
Authors: Krishan A. , Uzman B. G. 
Published: June 2020

The chromatoid body (“sphere chromatophile”) has recently been characterized in the developmental stages of animal sperm cells as a cytoplasmic structure rich in RNA and basic proteins but containing no DNA. In electron micrographs of widely divergent species several different structures have been designated chromatoid bodies: aggregates of dense granules; bodies with concentric membranous substructure; and tubules (500 A in diameter) arranged in parallel array.We shall describe, in early spermatocytes of the Syrian hamster, masses of fine, amorphous, electron-dense material adjacent to the nuclear membrane often in close proximity to nuclear pores (Figure 1); similar material has been so identified in other mammalian species. In later spermatocytes and in spermatids, this same material is recognized closely associated with the centriolar area which in these stages lies at the posterior end of the nucleus or sperm head.
Coprecipitation of Barium and Lead Sulfates
Authors: Takiyama Kazuyoshi 
Published: June 2020

Coprecipitation studies have been generally done from a stand point of analytical chemistry, but it is important to study on the coprecipitation from a view point of crystallography to clarify the mechanism of impurification of precipitates.Barium and lead sulfates belong to the orthorhombic system, Vh16, and the spacings of the crystals are slightly different from each other.
Gold Microcrystals of Pentagonal Symmetry
Authors: Bottoms W. R. , Morriss R. H. 
Published: June 2020

Face-centered cubic metallic crystals exhibiting fivefold symmetry have been observed by a number of investigators. Schwoebel has recently observed this anomalous structure in carbon replicas of gold which was vapor deposited onto electropolished gold single crystals. His results are consistent with a model proposed by Melmed and Hayward according to which the pentagonal crystal consists of five segments, each separated by a twin boundary. In an effort to explain this unusual morphology, Schwoebel has suggested the possibility of impurity atoms with a diameter approximately 0.7 that of gold serving as nuclei around which five gold atoms cluster in a modified close-packed arrangement.In this study microcrystals of gold exhibiting a similar structure have been observed in colloidal suspensions prepared by the chemical reduction of chlorauric acid with oxalic acid. The hydrosols contain gold particles of three general morphologies: thin platelets of trigonal symmetry, cube-octahedra with the {111} faces primarily developed and the {100} faces developed to a lesser extent, and particles exhibiting fivefold symmetry.
A Replica Technique for the Inside Surfaces of Small Diameter Pipes and Tubes
Authors: Gregory T. G. 
Published: June 2020

A nondestructive replica technique permitting complete inspection of bore surfaces having an inside diameter from 0.050 inch to 0.500 inch is described. Replicas are thermally formed on the outside surface of plastic tubing inflated in the bore of the sample being studied. This technique provides a new medium for inspection of bores that are too small or otherwise beyond the operating limits of conventional inspection methods.Bore replicas may be prepared by sliding a length of plastic tubing completely through the bore to be studied as shown in Figure 1. Polyvinyl chloride tubing suitable for this replica process is commercially available in sizes from 0.037- to 0.500-inch diameter. A tube size slightly smaller than the bore to be replicated should be used to facilitate insertion of the plastic replica blank into the bore.
The Preparation of Fine Recrystallized Tungsten Wire for Transmission Electron Microscopy
Authors: Koch E. F. , Walter J. L. 
Published: June 2020

In a study of the structure and properties of tungsten wire used for lamp filaments, it became desirable to perform transmission electron microscopy on the wire in the annealed as well as in the drawn condition.Wire used for lamp filaments is generally drawn to diameters less than 0.010" which is too fine for the preparation of transmission samples from single wires. Thus, it is clear that some assembly of wires must be used to form a “wire sheet” similar to that used by Glenn and Duff.Commercially-doped (218) tungsten filament wire in diameters of 0.001", 0.004", and 0.010" was wound on 1" square tungsten plates, 0.060" thick, using standard coil-winding techniques. After winding, the plates were annealed at temperatures of 1800°C to 2200°C, in vacuo. Following the anneal, the samples were treated in one of two ways. The 0.010" and 0.004" diameter wire sheets were encapsulated in epoxy and ground from both faces to a thickness of about 1/2 the wire diameter. The exposed wires were then electropolished with 107. NaOH electrolyte. The epoxy protected the edges of the flat wires so that the central area of the wire could be thinned.
A New High Resolution Transmission Electron Microscope with Second-Zone Objective Lens
Authors: Tochigi H. , Uchida H. , Shirai S. , Akashi K. , Evins D. J. , Bonnici J. 
Published: June 2020

A New High Excitation Objective Lens (Second-Zone Objective Lens) was discussed at Twenty-Sixth Annual EMSA Meeting. A new commercially available Transmission Electron Microscope incorporating this new lens has been completed.Major advantages of the new instrument allow an extremely small beam to be produced on the specimen plane which minimizes specimen beam damages, reduces contamination and drift.
The Ultrastructure of Muscular Cirrhosis of the Human Lung
Authors: Brinkman G. L. , Brooks N. L. 
Published: June 2020

Muscular cirrhosis of the lung is an uncommon form of idiopathic fibrosis in which excessive amounts of collagen and non-striated muscle form in the alveolar septa interfering with the transport of oxygen and carbon dioxide across the alveolar membrane.The patient in this case was a man aged 56 years, who had had progressive shortness of breath for three years. Thoracotomy was performed and the lingular lobe biopsied. The tissue was fixed in 3% phosphate buffered gluteraldehyde, and after dehydration in acetone, embedded in Vestopal. Thin sections were stained with uranyl magnesium acetate.
Temperature Dependance of Freeze-Etch Images
Authors: Staehelin L. Andrew , Bertaud William S. 
Published: June 2020

Freeze-etching has been termed the “true to nature” preparation method for electron microscopy because certain ceils remain viable throughout the treatment. However, even in the frozen state aqueous systems undergo various phase changes with temperature and little is known about the effects of these changes on frozen biological materials.Our present investigation was designed to provide some information as to what extent the temperature(s) at which the specimens are held during the various freeze-etch procedures can influence the final image of the material.
Nuclear Structure in Rainbow Trout Spermatozoa as Revealed by Freeze-Etching
Authors: Koehler James K. 
Published: June 2020

Freshly obtained milt from spawning rainbow trout were treated with 10% glycerol in fish ringer for several hours at 4°C. Centrifuged pellets of cells were frozen quickly in liquid freon 22 and examined by the freeze-etching method. Slowly frozen cells, or those treated with DMSO, gave generally poorer results than the method described above.Several sperm heads are seen in Figure 1. Note that the sperm tails are fractured away at the point of insertion into the head (arrows). The plane of fracture most commonly proceeded around the sperm head membrane, however, on occasion a cross fracture through the injclear region could be seen (Figure 2).
Principles and Techniques of Stereo Electron Microscopy
Authors: Cole Arthur 
Published: June 2020

Fig. 1 illustrates the basic principles of conventional stereo electron microscopy. An image is recorded for each of two tilt positions of the specimen. Consider the points A and B where B lies at the distance z below A. The displacements Pl and Pr produced by the tilt - ⊝ and + ⊝, are imaged as relative parallax displacements and on the film. When the stereo pair is viewed by binocular vision the positions of the points are reconstructed at A'” and B'”. For the conventional geometry used in electron microscopy (i.e., object size and objective aperture very small compared with the focal length) it can be shown that where M is the microscope magnification. Thus, a measurement of the parallax value determines z when M and ⊝ are known.Fig. 2 illustrates an instrument for viewing and analysing stereo pairs. Both plates are translated together by the master stage. Proper stereo alignment is achieved by use of sub-stages which allow rotation of either plate and translation of the right plate.
A New Electron Dense Stain For Elastin
Authors: Albert Ernest N. 
Published: June 2020

Only phosphotungstic acid (PTA) has been demonstrated to have a reasonably specific affinity for elastin in electron microscopy. However phosphotungstic acid is effective as a specific stain for elastin only at very acid pH. If the pH is increased, PTA is no more a specific stain for elastin, instead it acts as a general protein stain. Therefore at low pH only elastin is visible and one is unable to study the morphological relationships of the elastic components to their surrounding structures due to the virtual absence of contrast in them.Tetraphenylporphine sulfonate (TPPS) has, been shown to have a specific, affinity for elastic tissues of the body in fluorescence microscopy. However TPPS does not impart electron density to this tissue and thus is not suitable for electron microscopic studies. Therefore tetraphenylporphine sulfonate was complexed with various heavy metals in order to use it as a specific stain for elastin in electron microscopy.
A Compact Field Emission Scanning Electron Microscope
Authors: Welter L. M. , Coates V. J. 
Published: June 2020

A compact field emission scanning electron microscope has been developed and modeled after the optical microscope. The new instrument consists of the field emission electron gun, an externally adjustable aperture strip containing four different hole sizes, an electromagnetic single deflection system, an electromagnetic stigmator with independent magnitude and amplitude control, an ion pumped specimen chamber, and a television readout system. No magnetic lenses are used.The field emission electron gun incorporates an electrode system which simultaneously accelerates and focuses the electrons drawn from a field emission source. Several improvements have been made in the basic gun to provide for higher tip stability and reliability. A unique pumping scheme has been incorporated in the gun to provide tip region pressures in the order of 10-9 Torr and below so that stable field emission can be routinely obtained.
A Preparation of High Resolution Standards for Electron Microscopy. Part II
Authors: Tanaka Akira , Harling David F. 
Published: June 2020

In the previous paper, the author reported on a technique for preparing vapor-deposited single crystal films as high resolution standards for electron microscopy. The present paper is intended to describe the preparation of several high resolution standards for dark field microscopy and also to mention some results obtained from these studies. Three preparations were used initially: 1.) Graphitized carbon black, 2.) Epitaxially grown particles of different metals prepared by vapor deposition, and 3.) Particles grown epitaxially on the edge of micro-holes formed in a gold single crystal film.The authors successfully obtained dark field micrographs demonstrating the 3.4Å lattice spacing of graphitized carbon black and the Au single crystal (111) lattice of 2.35Å. The latter spacing is especially suitable for dark field imaging because of its preparation, as in 3.), above. After the deposited film of Au (001) orientation is prepared at 400°C the substrate temperature is raised, resulting in the formation of many square micro-holes caused by partial evaporation of the Au film.
New Possibilities for Electron Diffraction
Authors: Cowley J. M. 
Published: June 2020

Apart from its well-known applications for phase identification and determinations of geometry and orientations in conjunction with bright- and darkfield electron microscopy, electron diffraction has undergone considerable development in the last few years, principally in the direction of a more quantitative use of the technique. Computing methods are available for the calculation of intensities with arbitrary accuracy for well-characterized specimens. Instruments for the accurate measurement of diffracted intensities and for energy analysis have been developed. The major lack, in many cases, is a systematic method for combining data from diffraction and microscopy to determine the crystal morphology, perfection and orientation with sufficient precision. Each of these factors can affect the diffraction intensities strongly. Any one of them may be determined if the others and the crystal structure are known.In cases for which the specimen characteristics may be defined with sufficient precision, the comparison of intensities calculated by use of n-beam dynamical theory and experimental observation has shown excellent agreement and led to the determination of Fourier coefficients of potential distribution with an accuracy of the order of 0.5 per cent, which is more than comparable with the most precise X-ray measurements.