bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ratings of New Films for the High-Voltage Electron Microscope and the Radiation Damage Incurred in Taking Typical Biological Electron Micrographs
Authors: Vernon King Murray , Parsons Donald F. 
Published: June 2020

Radiation damage to biological specimens being examined in the electron microscope inevitably restricts the amount of information that can be gathered. This problem is especially severe in the high-voltage electron microscope (HVEM), where the relatively low sensitivities of existing photographic materials entail inordinately long exposures to specimens to the beam that cause enhanced radiation damage, in spite of early hopes that this instrument would alleviate the radiation-damage problem.We have reported studies of the sensitivities and resolutions of commercial and experimental photographic materials for use with 1-MeV electrons. In the present study, we have chosen certain photographic materials as representing typical films used for electron microscopy or as possessing a favorable combination of sensitivity and resolution for biological electron microscopy, and we have followed the course of impairment of image quality as a selected area of a typical specimen is subjected to ever larger radiation doses.
Transmission Electron Microscopy Studies of Crystal Lattice Growth in Atomic Resolution
Authors: Hashimoto H. , Kumaol A. , Ono A. , Watanabe E. , Endoh E. 
Published: June 2020

The present authors showed that the image of single atoms in Th-pyromellitate molecules and Th02 small crystals supported on graphite films could be observed in the dark field transmission electron microscopic images with tilted illumination (TDF image). The achievement of the observation of single atoms can be attributed not only to the high contrast of the dark field image but also to the two times higher resolution of the TDF image than that of the bright field image with axial illumination.Using the TDF image method, the growth process of small ThO2 crystals formed by the electron irradiation in the vacuum has been studied.Th - pyromellitate of 10-4 mol which was placed on graphite flakes was observed by JEM 100-C electron microscope with an objective lens of spherical aberration coefficient Cs = 0. 7 mm. Objective aperture and illumination tilt angles were 9 x 10-3 rad and 16 x 10-3 rad respectively .
Preliminary Observations of Electron Irradiation Damage in Short-Range Ordered Ni4Mo
Authors: Sinclair R. , Gelles D. S. , Thomas G. 
Published: June 2020

Short-range order (SRO) in a solid solution is an inherently stable state. It is a highly localised phenomenon, with atomic correlations rarely extending more than a few unit cells and which is difficult to study and interpret by conventional methods. It has been invoked as one of the possible causes of low swelling rates during irradiation of specific alloys. This idea is currently gaining some foundation especially as swelling has been found to be low in Cu 15%A1 and Ni4Mo, both of which are well-known SRO alloys.The present experiments are aimed at evaluating the behaviour of SRO Ni4Mo (produced by quenching from above the critical ordering temperature) in an irradiation environment. For this purpose, thin foils, prepared by electropolishing 3mm. discs in dilute H2S04 at room temperature, were examined in a JEOL high voltage electron microscope operating at lMeV (i.e. above the threshold displacement energy for both Ni and Mo).
Void-Lattice Formation in Natural Fluorite by Electron Irradiation
Authors: Murr L.E. 
Published: June 2020

The production of void lattices in metals as a result of displacement damage associated with high energy and heavy ion bombardment is now well documented. More recently, Murr has shown that a void lattice can be developed in natural (colored) fluorites observed in the transmission electron microscope. These were the first observations of a void lattice in an irradiated nonmetal, and the first, direct observations of color-center aggregates. Clinard, et al. have also recently observed a void lattice (described as a high density of aligned "pores") in neutron irradiated Al2O3 and Y2O3. In this latter work, itwas pointed out that in order that a cavity be formed,a near-stoichiometric ratio of cation and anion vacancies must aggregate. It was reasoned that two other alternatives to explain the pores were cation metal colloids and highpressure anion gas bubbles.Evans has proposed that void lattices result from the presence of a pre-existing impurity lattice, and predicted that the formation of a void lattice should restrict swelling in irradiated materials because it represents a state of saturation.
Identification of Faults in Asbestos Minerals and Application to Pollution Studies
Authors: Seshan K. , Wenk H.-R. 
Published: June 2020

Asbestos fibre texture occurs in various mineral groups (e.g. chrysotile, crocidolite, tremolite, grunerite, tourmaline) and it has been established that at least chrysotile is carcinogenic. We are investigating various aspects of the asbestos structure, with transmission electron microscopy (TEM) (1) in order to develop methods for unequivocal asbestos identification using minute samples and also to determine defects responsible for the fibre structure in these minerals which often occur as large, we 11-developed single crystals.In order to do this, we have started by investigating clinoamphibole asbestos such as tremolite Ca2Mg5[Si8O22] (OH, F)2 and crocidolite Na2 (Mg, Al, Fe3+, Fe2+) (Si8O22) (OH, F )2 , from California localities. In crocidoli te - asbestos we observed a high density of very narrow microtwins parallel to the fibre axis [001] (Fig. 1). They are often only 50-100Å wide. Diffraction patterns display the typical twin arrangement of spots and although preliminary contrast experiments are not yet conclusive the twin plane appears to be (100).
Structure of Al-Hf Films
Authors: Smith P. J. , Howard J. K. , Chu W. K. , Lever R. F. 
Published: June 2020

The structure of Al-Hf thin films, before and after annealing, has been studied by transmission electron microscopy. A 7000-Å layer of aluminum was evaporated, at a pressure of 5 x 10-7 Torr, onto a silicon wafer that had 5000 Å of thermal SiO2 on top. Onto the aluminum layer, with no break in the vacuum, a 1700-Å. layer of hafnium and then a 1000-Å layer of aluminum were deposited. The resulting three-layer structure was used to determine how different atomic ratios of Al and Hf influence the phases formed.After 4 hr of annealing at 400 C in a dry nitrogen atmosphere, the upper part of the film was found to be composed of grains of Al3Hf (ZrAl3-type), about 700 Å in diameter (Fig. 1). The reaction appeared to be complete in the upper layer; none of the relatively large Al grains, 2000 Å in diameter, that had been present in the as-deposited sample were found.
A Study of Gaseous and Organic Inclusions in Copper Electrodeposit by Transmission Electron Microscopy
Authors: Nakahara S. , Staudinger A. 
Published: June 2020

It was recently shown(1)that gaseous and organic inclusions in electrodeposits can he detected "by transmission electron microscopy (TEM) using a through-focus imaging technique. In this study, we have investigated the sites for incorporation of inclusions and their spacial distribution in copper electrodeposit by TEM.A copper film was electrodeposited on an annealed OFHC copper sheet in a sulfate electrolyte (200 g/l CuSo4-5H2O, 50 g/l H2So4) containing 5 M Mol./l O-phenanthroline as an organic additive. Plating was carried out at room temperature and at a current density of 5 MA/cm2.In order to detect gaseous and organic inclusions, all copper deposits were examined in overfocussed as well as underfocussed conditions. In each case, stereo-pairs(2)were obtained. Figures 1 and 2 show stereo-pairs of the deposited copper film taken in overfocussed and underfocussed conditions, respectively.
Mitochondrial Granules and Dehiscence of the Intercalated Disc in Cobalt Cardiomyopathy
Authors: Sekhri K.K. , Alexander C.S. , Nagasawa H J. , Derr R.F. 
Published: June 2020

It is now well established that cobalt was the primary etiologic agent in the “Beer Drinkers” cardiomyopathy which assumed epidemic proportions in recent years. The authors previously reported certain significant ultrastructural alterations in the liver and heart of cobalt treated rabbits. The present report confirms as well as extends the earlier findings on this subject.Ten rabbits were administered subcutaneously with a daily dose of 2.5 to 25 mg/kg of cobaltous chloride for 11-13 days. The control group of six rabbits received an equivalent dose of 2. 2% sodium chloride solution. The treated rabbits lost about 20% of their body weight and on sacrificing revealed flabby hearts, frequently with pericardial edema.
Chronic Laser Exposure Effects on Rabbit Retina
Authors: Silver Burton B. , Lawwill Theodore 
Published: June 2020

Dutch-belted 1 to 2.5 kg anesthetized rabbits were exposed to either xenon or argon laser light administered in a broad band, designed to cover large areas of the retina. For laser exposure, the pupil was dilated with atropine sulfate 1% and pheny lephrine 10%. All of the laser generated power was within a band centered at 5145.0 Anstroms. Established threshold for 4 hour exposures to laser irradiation are in the order of 25-35 microwatts/cm2. Animals examined for ultrastructural changes received 4 hour threshold doses. These animals exhibited ERG, opthalmascopic, and histological changes consistent with threshold damage.One month following exposure the rabbits were killed with pentobarbitol. The eyes were immediately enucleated and dissected while bathed in 3% phosphate buffered gluteraldehyde.
Cytoplasmic Organization in the Receptor Cells of the Crista Ampullaris
Authors: Dunn Robert F. 
Published: June 2020

Receptor cells of the cristae in the vestibular labyrinth of the bullfrog, Rana catesbiana, show a high degree of morphological organization. Four specialized regions may be distinguished: the apical region, the supranuclear region, the paranuclear region, and the basilar region.The apical region includes a single kinocilium, approximately 40 stereocilia, and many small microvilli all projecting from the apical cell surface into the lumen of the ampulla. A cuticular plate, located at the base of the stereocilia, contains filamentous attachments of the stereocilia, and has the general appearance of a homogeneous aggregation of fine particles (Fig. 1). An accumulation of mitochondria is located within the cytoplasm basal to the cuticular plate.
Regression of Sarcoma-180 after cis-Dichlorodiammineplatinum (II) : A Fine Structural Study
Authors: Sodhi Ajit 
Published: June 2020

Sarcoma-180, a transplantable tumor in Swiss White mice regresses completely after a single intraperitoneal injection of cis-Dichlorodiammineplatinum (II). Fine structural studies before and after cis (Pt (NH3)2C12) treatment show certain morphological changes indicative of possible mechanisms involved in the tumor regression. The mitotic activity of tumor cells is inhibited soon after platinum injection possibly due to its interaction with DNA. Appearance of plasma cells (Fig. 1) and lymphocytes within the tumor mass after a 4-6 days period of platinum treatment indicates a possible enhancement of the immune system. The plasma cells display a well developed RER and a typical nuclear morphology. Further studies on spleen of both treated and control animals show an increase in the number of plasma cells after about 5 days of platinum treatment (Fig. 2).The increase in the lymphocytes and the plasma cells indicates an immune system at the cellular level as these antibody producing cells directly come in contact with the Sarcoma-180 cells. Also the double diffusion method on agar plates indicates the enhanced humoral antibody production against Sarcoma-180 as opposed to the controls.
The Fine Structure of Calcoblasts in the Regenerating Sea Urchin Spine
Authors: Heatfield Barry M. , Travis Dorothy F. 
Published: June 2020

The endoskeleton of echinoderms is composed of fenestrated calcium carbonate (calcite) permeated by interconnecting channels filled with a variety of cell-types and extracellular fluid containing collagen fibrils. To identify and characterize skeletogenic cells and explore the mechanism of skeleton growth in echinoderms, tissues of regenerating spines of the sea urchin Strongylocentrotus purpuratus were examined by electron microscopy.The tip of the young regenerate is composed of two layers of tissue: an outer epidermis and an inner calcified dermis separated by a thin basal lamina (Fig. 1). In the apical dermis the skeleton consists of longitudinally oriented microspines interconnected by horizontal calcite bridges. During preparation of thin sections, skeletal mineral was lost, leaving a hole, indicated by (ms) in Figs. 1, 2, and 4.
Cuticular Pores in a Marine Mite
Authors: Crowe John H. 
Published: June 2020

Several species of marine mites are known to possess elaborate cuticular pores, the function of which is not known (Newell, 1947). In the present investigation the fine structure of the cuticular pores in a Halacarid mite, Copidognathus curtusi was studied, with a view towards discovering the function of the pores.For scanning electron microscopy the animals were fixed in cacodylatebuffered glutaraldehyde, post-fixed in osmium, and freeze-dried. For transmission electron microscopy they were fixed as above, embedded in Spurr's low viscosity epoxy resin, and sectioned on diamond knives.C. curtusi was chosen for study because of the abundance of pores in its cuticle.
Uultrastructure of Microtubules
Authors: Nagayama Ariaki 
Published: June 2020

Vinblastine(Vb) or vincristine, alkaloid derived from Vinca rosea is known for its antimitotic activity by regrouping of microtubules into paracrystalline form within the cells. A rapid purification method of vinblastine-induced microtubular paracrystals(PC) has provided us with a fresh and pure microtubular material demonstrating the presence of a labile ATPase associated with the PC. The present report is concerned with the fine structure of purified microtubules of mammalian cultured cells.Confluent monolayer cultures of L cells were incubated for 20hrs with 10-5 M Vb (donated from Shionogi Seiyaku & Co., Osaka, Japan).
The Morphology of Normal and Abberrant Murine Type Leukemia Virus and Its Relationship to Ribosomes
Authors: Tahmisian T. N. , Ainsworth E. J. 
Published: June 2020

Studies are in progress to characterize a transmissible leukemia and the causal agent which is presumably viral. The neoplasm, originally isolated from an aged irradiated B6CF1, mouse, has been transmitted in irradiated (200 R; 250 kVp X rays) weanling mice by intraperitoneal injection of millipore filtered (0.45μ) supernatant from spleen cell suspensions. At 22 days after filtrate injection in syngeneic mice, spleen, lymph nodes, and thymus were removed and prepared for electron microscopy to determine the presence of virus and morphology of viral development.The ultrastructure of cells from the above organs showed viral infection by a murine type leukemia virus with many “C” type buds 90 to 110nm formed in the cisternae of the rough endoplasmic reticulum (Fig. 1). The limiting membrane of the “C” type virus, apparently isolating it from the cytoplasm, is the unit membrane from the rough endoplasmic reticulum. The viral membrane is not invariably intact.
Freeze-Etch Replicas of the Mouse Proximal Tubule Cell
Authors: Spurlock Ben O. 
Published: June 2020

The fine structure of the mouse kidney has been studied in detail. Attempts at preserving this metabolically highly sensitive organ in the “closest to living state” have prompted some rather elaborate and involved methods of specimen preparation. Acknowledging that these techniques probably represent the best methods of preserving the integrity of this organ, it was felt that freeze-etch techniques might provide insight into structures heretofore unappreciated by conventional electron microscopy of thin sectioned material. The present report deals with the fine structure of the mouse renal proximal tubules as visualized in replicas of freeze-fractured and freeze-etched preparations.The left kidneys of lightly anesthesized mice were surgically exposed and fixed with 2% glutaraldehyde/0.1M phosphate buffer (pH 7. 2) by either the drip method (2) or by vascular perfusion (3). The kidneys were removed and stored in 0.1M phosphate buffer with 5% sucrose.
Relation Between the Function and the Ultrastructure of Profusely Appearing Microbodies in Hydrocarbon-Utiliizable Yeasts
Authors: Osumi M. , Fukui S. 
Published: June 2020

Many reports have been published on physiological activity and metabolism of hydrocarbon-utilizable fungi, but only a few results were reported on their ultrastructures. We found a number of microbodies in a cell of Candida grown in n-paraffin by electron microscopical observations. As similar microbodies in plant cells have been identified as the peroxisome, we studied catalase activity of Candida cells grown with hydrocarbon, and considered its relation to the microbody. We believe that this is the first report on the biogenesis of microbodies in yeasts, and is important in relation to the mitochondriogenesis.Seven strains of Candida were used in this study. Each strain was grown with n-paraffin mixture (C10-C12), inorganic salt medium at 30°C under shaking of 220 r.p.m. Respiratory activity, cytochrome synthesis, and catalase activity were measured. The localization of catalase was further examined by cytochemical methods with DAB (3.3'-diaminobenzidine). For electron microscopical observations, cells were fixed with glutaraldehyde-OsO4, or glutaraldehyde-KMnO4.
A Possible Origin of Myeloid Bodies in Oxygen Exposed Tissues
Authors: Takahashi Akira , Philpott Delbert E. 
Published: June 2020

Myelin-like figures or myeloid bodies occur in many tissues, especially after injury and with increasing age. The breathing of 100% oxygen also produces myeloid bodies.Tissues from rats exposed to 100% oxygen at one atmosphere for 72 hours were examined in the electron microscope. Samples from the brain, lung, spleen, heart and skeletal muscle, kidney and small intestine were fixed in glutaraldehyde, followed by osmium. Thin sections were stained in uranyl acetate and lead. Small myeloid figures which appeared as membrane pools, some showing Lamellae with about 45 Å spacing, were found in all the tissues examined. These figures were also found in the mitochondria and often gave the appearance of originating at this site (Figs. 1, 2, 3, 4). Invagination of membrane pooling occurs in places along the mitochondria. The various sizes of these membrane pools and possible extrusion and breakdown of the mitochondria suggests the mitochondria as a source of the myeloid bodies present after tissue damage from oxygen exposure.
High Spatial Resolution Auger Electron Spectroscopy
Authors: MacDonald Noel C. 
Published: June 2020

During the past several years, Auger electron spectroscopy (AES) has developed from a research curiosity to a practical surface chemical analysis technique. The practical applications of AES have been further increased by combining AES with simultaneous ion sputter etching; this powerful combination of AES and sputter etching is now routinely used to chemical profile thin film and other composite structures with a depth resolution of 10 - 50 Å. AES is sensitive to all elements except hydrogen and helium, and spectra for the majority of the elements are now cataloged in one reference source.AES is performed by electron bombarding a solid surface and energy analyzing the resulting secondary electrons. The secondary electrons that have undergone Auger transitions produce small peaks in the secondary electron distribution function, and the positions of these peaks in energy are used to identify the elements producing the transitions.
Description of a New High Resolution Scanning Transmission EM
Authors: Beer Michael , Wiggins J. W. , Woodruff David , Zubin Jon 
Published: June 2020

A high resolution scanning transmission electron microscope of the type developed by A. V. Crewe is under construction in this laboratory. The basic design is completed and construction is under way with completion expected by the end of this year.The optical column of the microscope will consist of a field emission electron source, an accelerating lens, condenser lens, objective lens, diffraction lens, an energy dispersive spectrometer, and three electron detectors. For any accelerating voltage the condenser lens function to provide a parallel beam at the entrance of the objective lens. The diffraction lens is weak and its current will be controlled by the objective lens current to give an electron diffraction pattern size which is independent of small changes in the objective lens current made to achieve focus at the specimen. The objective lens demagnifies the image of the field emission source so that its Gaussian size is small compared to the aberration limit.
A 700°C Hot Stage for the JEOL JSM-2 Scanning Electron Microscope
Authors: Maurin J. K. 
Published: June 2020

A heating device compatible with the standard JSM-2 goniometer stage has been developed, thereby providing rapid interchangeability between normal and hot stage microscopy. The hot stage is designed for temperatures ranging from 25 to 700°C and requires only minor modification to and interference with normal microscope functions. The heating carriage is inserted or removed through the airlock like a normal specimen holder; power and thermocouple leads are connected through the standard instrument patch board, and the main structural components consist of stainless steel, copper, nickel and sapphire. Other important internal components of this system include a large cryogenic surface above the specimen carriage and a water chilled base plate which replaces the normal solid dovetail plate. Externally, a direct current power source and a recorder to monitor temperature are required.Fig. 1 shows the arrangement of the heating device and electrical contacts. The hot stage consists of a carriage with the normal dovetail runners which supports the heating device, thermal shielding structure, and electrical connections.
A Novel Diode Detector in a Scanning Transmission Microscope
Authors: Kim C. S. , Everhart T. E. 
Published: June 2020

High-resolution in a scanning transmission electron microscope can be obtained using a condenser-objective lens. A suitable semiconductor diode is an efficient detector of high-energy electrons; an annular detector allows unscattered primary electrons or inelastically scattered electrons to pass through the hole, while elastically scattered electrons strike the diode, and are detected.Electrons passing through a thin sample may be elastically scattered through angles of many tens of milliradians, inelastically scattered with angular deflections of ∼ 1 mr, or not scattered at all. The inelastically scattered electrons do not depart significantly from the unscattered beam. Since the beam convergence angle at the sample is typically a few milliradians, the elastically scattered electrons can be collected using a detector with a hole positioned at the beam axis to allow the inelastically scattered electrons and the unscattered electrons to pass through. These electrons can be separated with an electron spectrometer to provide important contrast effects.