bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bone Response to Beta-methasone and Cortisol
Authors: Dockum N. L. , Murphy D. B. , Jee W. S. S. 
Published: June 2020

Analyses of undecalcified, decalcified, and plastic embedded bone specimens made by Jee following administration of Cortisol indicated a shift in the osteoclast versus osteoblast relationship with increased osteoclasts and a decrease in trabecular bone in the femur. Dockum and Jee reported daily injections of rats with 0.5 μCi of Pu239 for 3 to 7 days caused a shift in the osteoclast/osteoblast ratio increasing the number of osteoclasts to osteoblasts with a reduction in the amount of trabecular bone in the distal femur.Berliner et al., found that fluocinolone acetonide elicited changes in fibroblasts, namely, dilation of endoplasmic reticulum with the appearance of intracellular dense bodies.Fourteen six-week-old New Zealand white rabbits divided into two rabbits per group were given betamethasone in daily doses of 0.004, 0.012, 0.036, 0.100 and 0.300 mg/Kg of body weight for twenty days; one group received 1 mg/kg of Cortisol and one group served as controls.
The Morphology and Biochemistry of Isolated Skeletal Muscle Mitochondria
Authors: Dunn R. F. , Worsfold M. , Peter J. B. 
Published: June 2020

This is a preliminary report on our studies correlating the morphology and biochemical characteristics of mitochondria isolated from rat skeletal muscle. Figures 1 to 3 show sections of the mitochondrial preparations made on two separate occasions. These were sedimented from low speed supernatants at 3,500 g for 10 minutes (Figs. 1 and 2) or from a 3,500 g supernatant sedimented at 7,000 g for 10 minutes (Fig. 3). Polarographic traces of the respiration of the 3,500 g fractions from the two preparations, with pyruvate and malate as substrates, are shown in Figure 4.The mitochondria in the 70-3,500 g fraction from rat A (Fig. 1) were generally compact with closely packed cristae. Contamination with myofibrillar material was evident. In the 7,000 g fraction from the same animal, very few myofibrils were seen, and the mitochondria appeared distended and generally swollen (Fig. 3). The respiratory control ratio (RCR) of the 3,500 g mitochondria (Fig. 1) was 3.1 compared to 2.2 of the 7,000 g fraction (Fig. 3). Using our technique of preparation most of the mitochondria from rat skeletal muscle were sedimented at 3,500 g.
Ultrastructural Studies of Peripheral Nerves: Comparison of Regeneration to Normal Growth
Authors: Harkin James C. , Spurlock Ben O. 
Published: June 2020

If a peripheral nerve is cut, Wallerian degeneration and regeneration occur. The severed nerve can regenerate a myelin sheath mimicking normal development, however in contrast to normal growth the injured nerve is repaired in part by a collagenous scar. A peripheral nerve has a complex structure. A nerve fascicle contains axons sheathed by Schwann cells and by endoneurium composed of collagen, basement membranes and other extracellular components. Each fascicle is encased in a perineurial sheath and a number of these fascicles are further enclosed by epineurium. In present studies developing, adult, and regenerating peripheral nerves were examined in tissue sections of Maraglas embedded specimens in a Philips EM-300 or Siemens Elmiskop I electron microscope.In both normal and regenerating nerves the Schwann cell sheath is covered by a basement membrane. Schwann cells abut one another closely before axons traverse the gap between Schwann cells. Small axons appear earlier than large ones and non-myelinated before myelinated.
Erythrophagocytosis in the Liver in Hemolytic Anemias
Authors: Minick O. T. , Orfei E. , Volini F. , Kent G. 
Published: June 2020

Hemolytic anemias were produced in rats by administering phenylhydrazine or anti-erythrocytic (rooster) serum, the latter having agglutinin and hemolysin titers exceeding 1:1000.Following administration of phenylhydrazine, the erythrocytes undergo oxidative damage and are removed from the circulation by the cells of the reticulo-endothelial system, predominantly by the spleen. With increasing dosage or if animals are splenectomized, the Kupffer cells become an important site of sequestration and are greatly hypertrophied. Whole red cells are the most common type engulfed; they are broken down in digestive vacuoles, as shown by the presence of acid phosphatase activity (Fig. 1). Heinz body material and membranes persist longer than native hemoglobin. With larger doses of phenylhydrazine, erythrocytes undergo intravascular fragmentation, and the particles phagocytized are now mainly red cell fragments of varying sizes (Fig. 2).
Techniques Involved in the Acquisition of Serial Sections of the Atrioventricular Node for Light and Electron Microscopy
Authors: Emmett Sheila S. , Thaemert J. C. 
Published: June 2020

The acquisition of serial sections of the atrioventricular node for light and electron microscopy is a formidable task. Ordinary techniques are not adequate if the best possible results are to be achieved at the electron microscopic level. The techniques outlined below have proven to be valuable in locating and determining the position of the AV node.Whole hearts of 2-week old mice were fixed, in situ, by perfusion with 1% phosphate-buffered osmium tetroxide. The hearts were removed from the animals, sectioned transversely into 3 slices approximately equal in thickness, dehydrated in graded concentrations of ethanol and embedded in Epon 812. The block faces were trimmed to a trapezoidal shape ranging in size from 0.75 x 1 mm to 4 x 5 mm. Serial sections approximately 2 microns in thickness were cut with glass knives on a Porter-Blum MT-2 Ultramicrotome. While floating on a drop of water on the knife, each section was stretched with 1 drop of a 1:1, xylene in chloroform mixture applied directly to the section. The sections were picked up individually with a brush, transferred to a glass slide and oven dried for several hours prior to staining.
Deformation Twins in Drawn Aluminum - 0.9% Magnesium Wire
Authors: Dexter S. C. , Greenfield I. G. 
Published: June 2020

A number of mechanisms have been suggested for the formation of the duplex <111> + <100> fiber texture in drawn wires of face centered cubic metals. Ahlborn and Wassermann proposed that mechanical twinning and subsequent twin rotation are responsible for this type of texture. They theorize that during deformation a <111> direction in each grain becomes aligned parallel to the wire axis, and that mechanical twins form in this matrix with the <511> twin direction also parallel to the wire axis. Upon further deformation, the <100> twin direction which is about 19.5 degrees from the wire axis rotates and approaches the wire axis.Twins of this type and in a range of orientations corresponding to the rotation postulated were observed directly in drawn wires of Al - 0.9% Mg by transmission electron microscopy. The wires were cold drawn 96% to a final diameter of 0.038 inches. Longitudinal thin foils were prepared for electron microscopy in a two step process.
The Development of Voids in Nickel During Irradiation
Authors: Mastel B. , Brimhall J. L. 
Published: June 2020

Voids have recently been reported in stainless steel after irradiation to a high fast fluence (> 1022 n/cm2) at elevated temperatures. The presence of these voids was attributed to the high vacancy concentration resulting from the irradiation. In this paper we wish to report the formation of voids in high purity nickel after a relatively low exposure to neutrons.Nickel foil, 99-997% pure, in the form of disks 14 mm in diameter and 75μ thick was annealed at 700°C for one hour prior to irradiation. Irradiations were performed under two conditions: 1) in a NaK filled capsule equipped with thermocouples and a heater at a temperature of 400°C and 2) in a helium filled capsule at a calculated temperature of 400-450°C. Total neutron fluences were determined from flux wires and were 5 x 1019 n/cm2 and 4 x 1019n/cm2 (E > 1 MeV), respectively.
Practical High Resolution Microscopy
Authors: Marsh P. A. , Mullens T. , Price D. 
Published: June 2020

It is possible to exceed the guaranteed resolution on most electron microscopes by careful attention to microscope parameters essential for high resolution work. While our experience is related to a Philips EM-200, we hope that some of these comments will apply to all electron microscopes.The first considerations are vibration and magnetic fields. These are usually measured at the pre-installation survey and must be within specifications. It has been our experience, however, that these factors can be greatly influenced by the new facilities and therefore must be rechecked after the installation is completed. The relationship between the resolving power of an EM-200 and the maximum tolerable low frequency interference fields in milli-Oerstedt is 10 Å - 1.9, 8 Å - 1.4, 6 Å - 0.8.
An X-Ray Spectrometer Attachment for the Philips EM-200/EM-300 Electron Microscopes
Authors: Ogilvie R. E. , Moll S. H. , Schippert M. A. 
Published: June 2020

An X-ray spectrometer has been developed to extend the analytical capability of the Philips EM-200/EM-300 Electron Microscopes to studies of sample chemistry. It attaches directly to the objective aperture port of the rotating/tilting specimen stage.Shown in Figure 1, the spectrometer is a high resolution instrument, employing a mica crystal which is continuously curved to fulfill the X-ray focusing conditions over the entire angular range. Equipped with a flow proportional counter, it is capable of analyzing characteristic X-ray lines of any element from Na through U. With the rotating/tilting specimen stage and a replacement aperture installed in the microscope, the spectrometer may be attached to or removed from the instrument in less than five minutes. It may also be left in situ during normal use of the microscope.Supplementing the present ability of the electron microscope to investigate morphology and crystal structure (by electron diffraction), the spectrometer allows the simultaneous determination of chemical composition by microprobe X-ray fluorescence analysis of areas approximately one micron in diameter.
“High Resolution High Voltage Electron Microscopy”
Authors: Siegel Benjamin M. 
Published: June 2020

The potential advantages of high voltage electron microscopy for extending the limits of resolution and contrast in imaging low contrast objects, such as biomolecular specimens, is very great. The results of computations will be presented showing that at accelerating voltages of 500-1000 kV it should be possible to achieve spacial resolutions of 1 to 1.5 Å and using phase contrast imaging achieve adequate image contrast to observe single atoms of low atomic number.The practical problems associated with the design and utilization of the high voltage instrument are, optimistically, within the range of competence of the state of the art. However, there are some extremely important and critical areas to be systematically investigated before we have achieved this competence. The basic electron optics of the column required is well understood, but before the full potential of an instrument capable of resolutions of better than 1.5 Å are realized some very careful development work will be required. Of great importance for the actual achievement of high resolution with a high voltage electron microscope is the fundamental limitation set by the characteristics of the high voltage electron beam that can be obtained from the accelerator column.
Theory and Errors in Stereo Electron Microscopy
Authors: Pankratz J. M. 
Published: June 2020

It is often desirable in transmission electron microscopy to know the vertical spacing of points of interest within a specimen. However, in order to measure a stereo effect, one must have two pictures of the same area taken from different angles, and one must have also a formula for converting measured differences between corresponding points (parallax) into a height differential.Assume (a) that the impinging beam of electrons can be considered as a plane wave and (b) that the magnification is the same at the top and bottom of the specimen. The first assumption is good when the illuminating system is overfocused. The second assumption (the so-called “perspective error”) is good when the focal length is large (3 x 107Å) in relation to foil thickness (∼103 Å).
Test on Resolution of Electron Microscope Applied to Thick Specimens
Authors: Koike H. 
Published: June 2020

The popularity of the ultra high voltage electron microscope has resulted in a tendency to use thick specimens. R. Uyeda, Y. Kamiya, H. Hashimoto, and V. E. Cosslett reported the results of experiments and calculations determining to what thickness the electron microscope can observe specimens.Generally, in the case of thick specimens, the resolution in the microscope image depends on chromatic ‘aberration and when the energy distribution of electron beams, after being transmitted through the specimen, is measured, the resolution due to chromatic aberration can be obtained byIn practice, however, resolution depends on the position of the objects (e.g., irregularities such as lattice defects) in the specimen. This may be attributable to phase contrast due to interference phenomena and also attributable to the top-bottom effect pointed out by H. Hashimoto.
Background Gas Reduction in the Electron Microscope
Authors: Buvinger E. A. 
Published: June 2020

Today with special stages heating samples in the electron microscope to over 1000°C and resolutions of better than 10 Å required, the reduction of background gases in the microscope is more important than ever. Although the species which contaminate samples—oxygen, water vapor, various hydrocarbons, etc.—cannot be eliminated entirely without excessive time and expense, the equipment and procedures may be optimized so that these species are minimized.The microscope used for this study was an RCA EMU-3B with a universal chamber providing hot and cold staging. Since the pressure at the sample was of primary interest, an ionization gauge was mounted in the accessory port on the side of the universal chamber. This gauge gave immediate information concerning changes in column pressure which were not readily apparent on the panel meter.
The Use of Field Emission Tips in a Scanning Microscope
Authors: Crewe A. V. , Isaacson M. 
Published: June 2020

We have previously described an electron gun which uses a field emission tungsten tip as the source of electrons. In this paper we will discuss the practical aspects of the operation of such tips in an electron gun used in a scanning microscope.There are essentially three main criteria to be satisfied by these tips:The tungsten wire must be oriented so that a direction of intense emission is along the axis of the tip.The axis of the tip must coincide with the optical axis of the microscope.One must be able to obtain reasonable emission current (about 1 μ amp) at a low enough voltage (1-3 kV).It is well known that for single crystal tungsten, the planes of intense emission are perpendicular to the (310) and (111) directions (among others). Wire oriented with these directions along the axis can either be bought commercially or it can be cut by electrical discharge machining from a block of single crystal tungsten of known orientation.
Applications of Transmission Electron Microscopy in the Characterization of Metal Machinability
Authors: Murr L.E. , Draper A.B. 
Published: June 2020

The industrial characterization of the machinability of metals and alloys has always been a very arbitrarily defined property, subject to the selection of various reference or test materials; and the adoption of rather naive and misleading interpretations and standards. However, it seems reasonable to assume that with the present state of knowledge of materials properties, and the current theories of solid state physics, more basic guidelines for machinability characterization might be established on the basis of the residual machined microstructures. This approach was originally pursued by Draper; and our presentation here will simply reflect an exposition and extension of this research.The technique consists initially in the production of machined chips of a desired test material on a horizontal milling machine with the workpiece (specimen) mounted on a rotary table vice. A single cut of a specified depth is taken from the workpiece (0.25 in. wide) each at a new tool location.
A structural overview of the nucleus as derived from CCD-based 3-D optical microscopy
Authors: Paddy Michael R. , Hiraoka Yasushi , Chen Hans , Sedat John W. , Agard David A. 
Published: June 2020

The recent past has seen a renaisance in Cell Biology produced by the application of modern molecular tools. Unfortunately, structural adjuncts to this work have been limited by the fact that traditional non-symmetric structural approaches are not generally applicable to structures of the size encountered in Cell Biology. Over the last several years, our laboratory has developed three dimensional electron and optical microscopy methods which, when combined with specific dyes or modern immunocytological techniques, offer a very general approach to structural problems of this size scale.Our optical microscopy approach uses state-of-the-art digital image aquisition methods and modern computational capabilities to reconstruct three dimensional fluorescence images from a series of two dimensional optical sections. In broad terms, this general approach breaks into three significant elements: 1) aquisition of digital optical microsope images of exceptional quality through the use of a charge coupled device (CCD) imager; 2) computational removal of out of focus information that contaminates each image in the three dimensional data stack; and 3) schemes for visualization and analysis of the resulting three dimensional image.
Long-term observation of cultured cells by interference-reflection microscopy: near infrared illumination and Y-contrast image processing
Authors: Zand M. S. , Albrecht-Buehler G. 
Published: June 2020

Analysis of dynamic changes in cell-substratum adhesion patterns during cell locomotion requires continuous, extended observation of single living cells. To date, interference-reflection microscopy (IRM) is the only method available to visualize cell -substratum adhesions in vitro. This method uses 1% of the incident illumination to produce an IRM image, and so far requires use of a high intensity visible light source (400 - 800 nm). However, light of this intensity and spectral range induces marked changes in fibroblast behavior, including cessation of locomotion. Therefore, we developed a method allowing continuous IRM observation of live cells for up to 8 hours, without any observable changes in normal cell behavior, using near infrared illumination (750-1100 nm). In addition, we use Y-contrast image processing of IRM images to create a 3-dimensional relief of the ventral cell surface.Single locomoting PTK1 cells were observed continuously in IRM with time lapse video recording for periods of up to 8 hours.
Application of solid-phase immune electron microscopy to study physical and stability characteristics of enterically transmitted non-a, non-b hepatitis virus
Authors: Humphrey Charles D. , Cook E. H. , McCaustland Karen A. , Bradley Daniel W. 
Published: June 2020

Enterically transmitted non-A, non-B hepatitis (ET-NANBH) is a type of hepatitis which is increasingly becoming a significant world health concern. As with hepatitis A virus (HAV), spread is by the fecal-oral mode of transmission. Until recently, the etiologic agent had not been isolated and identified. We have succeeded in the isolation and preliminary characterization of this virus and demonstrating that this agent can cause hepatic disease and seroconversion in experimental primates. Our characterization of this virus was facilitated by immune (IEM) and solid phase immune electron microscopic (SPIEM) methodologies.Many immune electron microscopy methodologies have been used for morphological identification and characterization of viruses. We have previously reported a highly effective solid phase immune electron microscopy procedure which facilitated identification of hepatitis A virus (HAV) in crude cell culture extracts. More recently we have reported utilization of the method for identification of an etiologic agent responsible for (ET-NANBH).
Correlated confocal laser scanning microscopy with high-voltage electron microscopy of focal contacts in 3T3 cells stained with napthol blue black
Authors: Paddock S. W. , Cooke P. H. 
Published: June 2020

We used the MRC-500 confocal laser scanning microscope (LSM) in the reflecting mode, rather than the fluorescent mode, to produce high-resolution images of cytoskeletal structures in 3T3 cells stained with Napthol Blue Black (NBB). High voltage electron microscopy CHVEM) of the same cells confirmed that structures at the cell/substratum interface imaged with the LSM are “focal contacts,” regions of cell attachment to the substratum.Swiss 3T3 cells were cultured on Formvar/carbon-coated gold finder grids in Dulbecco's Modified Eagles medium containing 10% calf serum in saturated humidity and 10% CO2at 37°C. Preconfluent cultures growing on the grids were fixed in a detergent/glutaraldehyde fixative for 10 minutes, stained with 0.2% NBB in methanol/acetic acid/water for 30 minutes, rinsed several times in distilled water, mounted in simple chambers in distilled water and examined in the LSM operated in the reflecting mode.
A new cryofixation device (CF 100)
Authors: Livesey S.A. , Linner J.G. , Piunno C. 
Published: June 2020

The aim of this project was to develop an ultrarapid cooling device which optimized the parameters of metal mirror cryofixation, minimized operator dependence and was configured for cost efficient and low maintenance operation.Cooling of the cryogenic surface is accomplished by flow through of liquid nitrogen at 20 PSI to allow attachment directly to a standard liquid nitrogen tank. Cooling time +25 to -185°C is 45 seconds measured with thermocouple bonded to the upper cryogenic surface.Atmospheric contamination of the cryogenic surface during cooling is prevented by a surrounding vacuum. Precooling of the sample is avoided by reversal of surrounding vacuum by room temperature ultrapure nitrogen gas at the time of sample application. Atmospheric contamination of the cryogenic surface during application of the sample is prevented by the nitrogen atmosphere and functional interaction of shutter retraction and plunger activation.Bounce of sample is eliminated by sample holder design and use of a pneumatic plunger at selectable PSI to ensure linear force of application.
Low-Voltage Accelerating-Voltage SEM Magnification Standard Prototype
Authors: Postek M. T. , Tiberio R. C. 
Published: June 2020

The National Bureau of Standards has had a continuing effort for almost a decade to develop feature-size measurement techniques and the associated linewidth standards for the semiconductor industry. Recently, work began on a scanning electron microscope (SEM) based feature-size measurement program specifically aimed at the development and certification of SEM linewidth standards and the associated techniques for their calibration and use.Primary to the development and use of SEM linewidth measurement standards is the calibration of the magnification of the SEM. The only standard reference material presently available from NBS for calibrating the magnification of the SEM is the NBS SRM 484.1 This standard provides a known pitch between gold lines in a nickel matrix that is traceable to NBS primary standards. This standard has proven useful for many SEM applications and should continue to be useful for some time to come. However, since SRM 484 was developed prior to the recent interest in low accelerating voltage operation for integrated circuit wafer inspection and measurement, this SRM, in its present form, is unsuitable for use in many of the newly introduced SEM measurement instruments.