bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Nature of Rapidly Extracted Phycocyanin from the Blue-Green Alga Plectonema Boryanum
Authors: Kessel M. , MacColl R. 
Published: June 2020

The major protein of the blue-green algae is the biliprotein, C-phycocyanin (Amax = 620 nm), which is presumed to exist in the cell in the form of distinct aggregates called phycobilisomes. The self-assembly of C-phycocyanin from monomer to hexamer has been extensively studied, but the proposed next step in the assembly of a phycobilisome, the formation of 19s subunits, is completely unknown. We have used electron microscopy and analytical ultracentrifugation in combination with a method for rapid and gentle extraction of phycocyanin to study its subunit structure and assembly.To establish the existence of phycobilisomes, cells of P. boryanum in the log phase of growth, growing at a light intensity of 200 foot candles, were fixed in 2% glutaraldehyde in 0.1M cacodylate buffer, pH 7.0, for 3 hours at 4°C. The cells were post-fixed in 1% OsO4 in the same buffer overnight. Material was stained for 1 hour in uranyl acetate (1%), dehydrated and embedded in araldite and examined in thin sections.
High Voltage Electron Microscopy of Poxvirus Nucleoid Material
Authors: Grimley P. M. 
Published: June 2020

Appearance of an eccentric nucleoid within developing poxvirus envelopes is the first ultrastructural evidence of core differentiation. Subsequently, the nucleoid elongates and is flanked by lenticular densities known as lateral bodies. When mature, it collapses into a biconcave form. In ultrathin sections, the eccentric nucleoid usually appears compact; although in the elongate stage central spaces may be apparent. Normally, the stages of poxvirus maturation are asynchronous and difficult to examine in order. Treatment of infected cells with rifampin provides a useful experimental approach for examining the development of nucleoid material.HeLa cells were treated with rifampin (100µg/ml) during an 8 hr. infection with vaccinia virus. Rifampin interrupts vaccinia morphogenesis at a stage prior to the formation of coated envelopes, and membranous precursors of envelopes accumulate. When the drug is washed out, large numbers of virus envelopes form simoultaneously (Fig. 1).
Nucleated and Anucleated Spermatozoa in Inseminated Female Silkworms
Authors: Friedländer M. 
Published: June 2020

The silkworm Bombyx mori, like other moths, produces both typical-haploid and atypical-anucleate spermatozoa. Typical spermatogenesis takes place in the larva and ceases in the pupa, while atypical spermatogenesis starts in the pupa and continues in the adult. Typical spermatozoa fertilize the eggs. The function of the atypical spermatozoa is unknown and even their presence in the inseminated female is uncertain.Genital ducts of inseminated female silkworms were studied to find out whether the atypical spermatozoa reach the female, and if they do, to determine their fate. The changes in the spermatozoa during the process of capacitation were also studied. Ducts were fixed in 1.7% glutaraldehyde in 0.1M phosphate buffer, pH 7.3, refixed in OSO4, embeded in Epon, and examined.
Useful Resolution Standards for Freeze-Cleave and Etch Replication Techniques
Authors: McNutt N. Scott , Weinstein Ronald S. 
Published: June 2020

Kreutziger has noted that obscuration of hexagonal arrays of depressions (pits) in the inwardly-directed face (face B) of membranes at the nexus can be a result of specimen surface contamination and that the visualization of these pits can be used as a quality test for freeze-cleave and etch replicas. During our study of nexus membranes, we observed that pits in nexus face B can be observed in replicas which by other criteria would be judged as quite crude. We now suggest two images which can be used conveniently as resolution standards and which have been seen only in high quality replicas.Rabbit and human erythrocytes were isolated from fresh blood by differential centrifugation and glycerinated to 20% glycerol in 0.9% NaCl. Yeast cells (Saccharomyces cerevisiae) were grown on Sabaroud's medium at room temperature, harvested, and glycerinated to 10% glycerol in 0.9% NaCl. Mouse cardiac muscle was fixed in 1% glutaraldehyde-0.1M cacodylate buffer, pH 7, for 15 minutes and then glycerinated to 10% or 20% glycerol in 0.9% NaCl. Erythrocytes or yeasts were centrifuged into a loose pellet which was used as a mounting support matrix around specimens of cardiac muscle on the specimen holder of an MGH-Type II simple cold block freeze-cleave device.
High Voltage Electron Microscopy in Europe
Authors: Cosslett V. Ellis 
Published: June 2020

There are two well established high voltage microscopy laboratories in Europe, several new installations and a few experimental instruments still in the development stage. The latest information about each of these projects will be presented.C.N.R.S. Laboratory, Toulouse, France: The 3 MV microscope is in operation. In initial tests, micrographs of 5 μm stainless steel have been obtained at 2 MV. The HV generator and the lens current systems have been described, as well as the microscope itself. Many studies, mainly of physical aspects of high voltage microscopy, have been made with the 1.5 MV instrument.Cavendish Laboratory, Cambridge, England: A great variety of research projects are under investigation on the “home-built” 750 kV microscope, in biology as well as in metallurgy and polymer science. Quantitative studies have been made of energy loss in typical materials, and of the sensitivity and resolution of viewing screens and photographic emulsions. Special stages and other apparatus have been developed.
Herpestype Virus and Type C Particles in Spontaneous Equine Lymphoma
Authors: Maruyama K. , Swearingen G. R. , Dmochowski L. , Jardine J. H. , Joiner G. N. 
Published: June 2020

Herpestype and type C virus particles are known to produce tumors in animals of certain species, and to be present in a variety of human tissues. Similar particles were found in a horse lymphoma.Electron microscope study was carried out on a tumorous prescapular lymph node from an adult female horse with spontaneous lymphoma. Lymph node cells grown in vitro for a total of 105 days (6th passage) were also studied. The lymph node was infiltrated by blastic cells of reticulum cell type and of lymphoblast type. No virus particles were found in the original lymph node. The cultured cells have a large cytoplasm with well developed rough endoplasmic reticulum and Golgi's apparatus, and an indented nucleus with marginated chromatin. Occasionally, intranuclear fibrous structures were observed. Elongated nuclear protrusion were frequently seen.
Hydration Chamber for Jeolco 200 Kv Microscope
Authors: Matricardi V. R. , Hausner G. G. , Parsons D. F. 
Published: June 2020

In order to observe room temperature hydrated specimens in an electron microscope, the following conditions should be satisfied:
The specimen should be surrounded by water vapor as close as possible to the equilibrium vapor pressure corresponding to the temperature of the specimen.The specimen grid should be inserted, focused and photo graphed in the shortest possible time in order to minimize dehydration.The full area of the specimen grid should be visible in order to minimize the number of changes of specimen required.There should be no pressure gradient across the grid so that specimens can be straddled across holes.Leakage of water vapor to the column should be minimized.
Interfacial Dislocations in (111) Ag-Cu Bilayers
Authors: Homg C. T. , Vook R. W. 
Published: June 2020

Smooth (111) single crystal Cu films (1200Å) were evaporated on NaCl/mica in an ultra-high vacuum RHEED systemI (base pressure ≤1×10−9 torr) The total residual gas pressure during Cu evaporation was less than 1×10−8 torr. These Cu films served as substrates for thin epitaxial monolayer Ag growth ranging in thickness from 1Å to 20Å, as measured by a quartz thickness monitor. These Ag-Cu bilayers were formed and examined in-situ in the RHEED system.The unusual RHEED patterns first re orted by Gradmann and Krause were observed in the present work up to l0Å of Ag. Beyond 10Å, only Ag and Cu lines plus double diffraction effects were detected. A typical example of the former is given in Fig. 1. The pattern was previously interpreted as due to a two dimensional grid of interfacial dislocations.
Microstructures of the Superplastic Al-Zn Eutectoid Deformed at Constant Strain Rates
Authors: Franti G. W. 
Published: June 2020

Much of the work on the deformation behavior of superplastic alloys has been carried out using constant velocity testing. In constant velocity testing, the true strain rate is continuously decreasing with strain and the effect of the strain based on the deformation behavior is difficult to assess.In the present study, an Instron tensile testing machine (Model TT-CM-L) was modified with the addition of a small analog computer to yield true constant strain rates in the range of 10−4 min.−1 to 10 min.−1The Al-Zn eutectoid was cast from the pure metals and hotrolled to a 75% reduction in area. Tensile samples of 0.475 cm gauge diameter and 3.50 cm guage length were homogenized at 375°C for three hours and ice-water quenched. Prior to testing, samples were annealed at 250°C for three hours to yield an average grain size of one micron.
Reconstruction of Objects from their Projections Using Orthogonal Functions
Authors: Zeitler Elrnar 
Published: June 2020

Considering any finite three-dimensional object, a “projection” is here defined as a two-dimensional representation of the object's mass per unit area on a plane normal to a given projection axis, here taken as they-axis. Since the object can be seen as being built from parallel, thin slices, the relation between object structure and its projection can be reduced by one dimension. It is assumed that an electron microscope equipped with a tilting stage records the projectionWhere the object has a spatial density distribution p(r,ϕ) within a limiting radius taken to be unity, and the stage is tilted by an angle 9 with respect to the x-axis of the recording plane.
Origin of Hepatic Nuclear Inclusion Bodies
Authors: Zaki F. G. , Greenlee J. A. , Keysser C. H. 
Published: June 2020

Nuclear inclusion bodies seen in human liver cells may appear in light microscopy as deposits of fat or glycogen resulting from various diseases such as diabetes, hepatitis, cholestasis or glycogen storage disease. These deposits have been also encountered in experimental liver injury and in our animals subjected to nutritional deficiencies, drug intoxication and hepatocarcinogens. Sometimes these deposits fail to demonstrate the presence of fat or glycogen and show PAS negative reaction. Such deposits are considered as viral products.Electron microscopic studies of these nuclei revealed that such inclusion bodies were not products of the nucleus per se but were mere segments of endoplasmic reticulum trapped inside invaginating nuclei (Fig. 1-3).
Scanning Electron Microscopy of Vascular Casts For the Study of Vessel Connections in a Complex Vascular Bed - The Trout Gill
Authors: Gannona B.J. , Campbell Graeme , Randall D.J. 
Published: June 2020

The microcirculation of fish gills has been investigated by light microscopic study of sample or serial sections, transmission electronmicroscopy, and microscopic study of intact Blood or ink filled gill filaments; it is considered to consist of a series of respiratory pathways and non-respiratory shunts.However, reconstruction of a complex 3 dimensional structure from 2. dimensional information, as is available from section study, is fraught with difficulty, especially in establishing connections between micro-vessels. Also, investigation of intact specimens is hampered by poor resolution and inadequate depth perception into the tissue.Perfusion of the microcirculation with a liquid plastic mixture which will polymerise in situ produces a mechanically selfsupporting object, after tissue removal, for study with the S.E.M; this approach permits direct examination of the microvasculature in three dimensions.
Nucleolus-Like Cytoplasmic Body in a Pyramidal Cortical Neuron in a Normal Cat
Authors: Feria-Velasco Alfredo 
Published: June 2020

Cytoplasmic bodies resembling nucleolus have been reported in the literature to be present in various types of cells, specially in nerve cells. This type of structure has been frequently observed in nerve cells of dorsal nucleus of the vagus and in some hypothalamic nuclei. There is only one communication as to the occurrence of a nucleolus-like structure in cortical nerve cells (entorhinal cortex) of mice previously injected with puromycin intracerebrally.In the present work, it is reported the presence of a nucleolus-like body in the cytoplasm of a motor cortical pyramidal nerve cell of a normal cat. The animal was not receiving any type of treatment which would interfere with protein synthesis. Its behavior and electronencephalographic records were within normal limits.
Fine Structural Localization of Intravenously Injected Cytochrome C in the Porcine Choroid Plexus
Authors: Davis D. A. , Milhorat T. H. , Lloyd B. J. 
Published: June 2020

In the continuing search for suitable markers that can be used for examining mechanisms of cerebrospinal fluid (CSF) formation, we were recently led to a study of cytochrome c. This hemo-chromogen has two primary advantages as a marker: 1. It is g. considerably smaller protein (molecular wt. 13,000, radius 15 Å) than ferritin (molecular wt. 400,000, radius 5 Å) or horseradish peroxidase (molecular wt. 40,000, radius 25-30Å) ; 2. It is easily visualized by electron microscopy after reaction with 3,3'-diaminobenzidine (dab).Cytochrome c (Cal Biochem Grade A) was administered intravenously to pigs (7-9 kg. in wt.) in doses of 25-30 mg./100 g. wt.
Growth instability of polyethyleneterephthalate oligomer crystals
Authors: Perovic Aleksandra 
Published: June 2020

The growth forms of crystals have been an ongoing subject of interest to scientists and an enormous amount of factual material has been accumulated and a comprehensive theory of crystal growth has evolved. One of the most interesting aspects of the growth of regular, polyhedral crystals is that of relating to the establishments of the stability conditions governing the transformation of regular crystal shapes into hopper, skeletal or dendritic shapes.The growth features of instability conditions have been observed in hexagonal plate-like oligomer crystals in polyethyleneterephthalate forming on the surface of the film during annealing. Figures 1(a) and (b) represent scanning electronmicrographs of oligomer crystals developed on the surface of polyethyleneterephthalate film during heat treatment. The hexagonal plates have smooth basal faces.
High-resolution TEM and analytical study of second-phase particles in Al2O3
Authors: Morrissey K. J. , Kouh Y. , Carter C. B. 
Published: June 2020

The influence of additives such as MgO, NiO, and ZrO2 and impurities such as Na, K, and Ca on the sintering of alumina compacts has been the focus of a considerable amount of research. Since these additives affect compact density and grain size it is of interest to determine the behavior of the elements during processing. That is, it is important to know whether Ca and Mg segregate to grain boundaries or are located in the second-phase particles. Current results suggest that Ca is found uniformly at the grain boundaries and that Mg is accommodated in the second-phase particles.The present investigation is concerned with identifying second-phase particles in different commercially-produced Al2O3 compacts and studying both their structure and composition. Preliminary results have been discussed previously. The investigation has dealt mainly with two different alumina compacts. One compact was prepared from an initial powder containing 0.25% MgO, a small amount of intentionally added Ni, and was prepared by hot pressing.
Microstructure of highly reactive submicrometer TiB2 powders
Authors: Angelini P. , Lehman G. L. , Brynestad J. 
Published: June 2020

Research has begun involving the pressing and evaluation of TiB2 compacts produced from submicrometer-sized TiB2 powder. Among the advantages offered by the use of such starting powder are that sintering and densification may be performed at relatively low temperatures (1400°C), limited grain growth may occur (<1 μm grains), and densification may proceed without the need of binder phases. However, one of the difficulties with the use of such powder is that it oxidizes rapidly when exposed to air. Thus processing may need to be performed under inert conditions.Powders analyzed in this study included those exposed to air, to water, and only to an inert atmosphere (He). Large particle size material can tolerate exposure to air, but small particle size powder must first be exposed to H2O before being exposed to air. This exposure can modify the as-produced powder either by oxidation or dissolution processes.
Lithography below 100 nm
Authors: Jackel L. D. 
Published: June 2020

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile”	, also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.
Evaluation of single-electron movies of glutamine synthetase molecules
Authors: Kunath W. , Zeitler E. , Kessel M. 
Published: June 2020

The features of digital recording of a continuous series (movie) of singleelectron TV frames are reported. The technique is used to investigate structural changes in negatively stained glutamine synthetase molecules (GS) during electron irradiation and, as an ultimate goal, to look for the molecules' “undamaged” structure, say, after a 1 e/Å2 dose.The TV frame of fig. la shows an image of 5 glutamine synthetase molecules exposed to 1/150 e/Å2. Every single electron is recorded as a unit signal in a 256	×256 field. The extremely low exposure of a single TV frame as dictated by the single-electron recording device including the electron microscope requires accumulation of 150 TV frames into one frame (fig. lb) thus achieving a reasonable compromise between the conflicting aspects of exposure time per frame of 3 sec. vs. object drift of less than 1 Å, and exposure per frame of 1 e/Å2 vs. rate of structural damage.
Development of an electron energy loss spectrometer (H-8020) for 200kV ATEM
Authors: Kobayashi H. , Isakozawa S. , Kamimura S. , Okamura S. 
Published: June 2020

We have developed an electron energy loss spectrometer (H-8020) for a 200kV electron microscope (H-800).(Fig. 1) This spectrometer utilizes a sectorQtype electro-magnet with a radius of 132 mm and a deflection angle of 90°. The magnet allows 3-dimensional beam focus. There is an alignment coil and stigmator built-in at the entrance of the magnet to ensure good resolution. At the outlet of the magnet, there is a pair of electrodes. An RF voltage, which is synchronized with a rockin- amplifier, is applied as a carrier wave across the electrodes. Thus, electron energy loss spectrum is detected in a differentiated form so that back ground noise of the spectrum is eliminated and it permits elemental mapping image of a specified element. In addition, we have incorporated a CRT for monitoring spectrum and such new functions as auto main peak search, auto gain control for improved overall operation.Fig. 2 is an example of energy resolution of aluminum evaporated film. It shows 2eV resolution at 200kV.Fig. 3 is an example of boron nitride (BN). It shows fine structures at the edge of B-K peak.
Development of an automatic electron diffraction pattern analyzing system
Authors: Moriguchi S. , Shinkawa T. , Watanabe E. , Makita Y. , Sakurai S. , Kokubo Y. , Tokiwai M. 
Published: June 2020

The electron diffraction pattern has information on the crystal structure of samples, such as the crystal system, lattice constants and the orientation for the incident beam. Material can be identified by measuring the above characteristics and, in general principle by measuring their accurate lattice spacings. However, this measurement requires a lot of time and fundamental knowledge of the crystal structure.The present automatic analyzing system of the electron diffraction pattern makes the analysis ease. The outline of this system is described in this paper.The hardware system consists roughly of three components; a low-light-level TV device called the image carrier, a frame memory, and a minicomputer. The image carrier transforms the image formed on the flourescent screen of a transmission electron microscope (TEM) into video signals. The frame memory is provided with a memory plane of 512 x 512 pixels, each having 256 gray levels. It digitaizes video signals of the image and stores them in itself.
Selective contrast in images of crystalline cytochrome oxidase dimers
Authors: Frey T. G. , Costello M. J. , Reardon J. E. , Frey P. A. 
Published: June 2020

Vesicle crystals of cytochrome oxidase dimers embedded in the phospholipid bilayer of a collapsed vesicle are produced when beef heart mitochondria are treated with Triton detergents. The crystals have the symmetry of plane group p22121 with unit cell dimensions of a=95 A, b=125 A, and c=210 A. The molecules protrude 60 A beyond the lipid bilayer on the inside of the vesicle, but very little beyond the bilayer on the outside. Decoration of crys- stals with subunit-specific antibodies identified the outside surface of the vesicle crystals as corresponding to the M-side (matrix) of the inner mitochondrial membrane and the inside surface as the C-side (cytoplasmic).We have used various methods of specimen preparation to selectively image different regions of the dimer crystals in order to correlate the structure of dimers with that of 'Y'-shaped monomers. Electron micrographs of negatively stained specimens (Fig. 1a, 2a) give a two-dimensional projection of the three-dimensional stain replica of the entire structure.
Molecular structures of isolated lung basement membranes in man
Authors: Lee Y.S. , Juan S.Y. , Chang C.H. 
Published: June 2020

Basement membranes, the extracellular structures close to the plasma membranes, have been suggested to have differences in chemical and molecular structures to serve a wide variety of functional roles in different tissues. Although the chemical compositions of the basement membranes are well known the molecular organization within the membrane matrices remains unclear. Recently, several investigators have proposed different models for the organization of collagen molecules in the basement membranes. In fact, these models are actually unable to represent the molecular structures within the native basement membranes. Since there has been no direct knowledge regarding the molecular structures in the lung basement membranes the purpose of the present investigation is to characterize the internal structures of the isolated lung basement membranes at the molecular level by the conventional electron microscope technique.This study was carried out on human lung specimens which were obtained from 6 autopsy patients.