bluuebunny/crossref_metadata_2025 huggingface dataset:
The Identification of the Amino Acid Acceptor Terminus of tRNAPheyeast
Authors: Korn A.P. , Ottensmeyer F.P.
Published: June 2020

Employing the technique of beam tilt dark field electron microscopy we have been able to visualize in biological macromolecules structural details down to as much as 5 Å in size (1). In addition, images of individual heavy atoms have been obtained. These two achievements open the door to a new field of structure determination of proteins and nucleic acids: if a group of heavy atoms can be reacted specifically with a key position in the molecule, that position in the electron micrograph will be recognized by virtue of the presence of a cluster of heavy atom spots in that region. Requirements for the heavy atom reagent are 1) that it react specifically, 2) that the reaction conditions be sufficiently mild that the molecule is in its “native” conformation, and 3) that the presence of the heavy atom reagents not perturb the conformation of the molecule, at least to the extent that it can be detected by the technique.
A Review of the Various Usages of Energy Dispersive X-Ray Analysis in Biology
Authors: Mizuhira V.
Published: June 2020

The electron microscope fitted with an electron probe X-ray microanalyzer is a unique method for detecting the fine distribution of elements in fine structure by using a very small electron beam spot. The characteristic X-ray energy or wave length of the element can be ascertained by the aid of energy dispersive or wave length dispersive X-ray detectors with an amplifier and a display system. The energy dispersive type, which is a nuclear diode Si-detector (NDS), has very high inherent efficiency in detecting X-rays as compared to the wave length dispersive type detector. The NDS type detector system analyzes the elements from sodium to uranium simultaneously within a very short time. These characters are very useful for biological applications, although NDS has some characteristic demerits which cause difficulty in the identification of superimposed spectra, as will be described later.
Modification of Philips Em 301 for Optimum Edx Analysis
Authors: Hren J. J. , Ong P. S. , Johnson P. F. , Jenkins E. J.
Published: June 2020

It is well recognized that the incorporation of STEM into commercial electron microscopes offers potential advantage for EDX analyses as well. The microscope requirements for high resolution EDX are severe for even qualitative compositional measurements of regions excited by electrons beams approximately 100Ådiameter. We report here on some modifications of a Philips EM 301 equipped with STEM and an Ortec Model 6200 EDX system aimed at improving the EDX capability.

Geiss and Huang (1) earlier reported similar studies on metallic alloy films. Our intention is to look at low solute concentrations in both crystalline and amorphous materials, including biological specimens. Thus, we are especially concerned about ultimate sensitivity and resolution for compositional measurements. In turn, these goals dictate special attention to sources of background and secondary excitation.
Energy Dispersive X-Ray Measurements of thin Metal Foils
Authors: Bentley J. , Kenik E. A.
Published: June 2020

Instruments combining a 100 kV transmission electron microscope (TEM) with scanning transmission (STEM), secondary electron (SEM) and x-ray energy dispersive spectrometer (EDS) attachments to give analytical capabilities are becoming increasingly available and useful. Some typical applications in the field of materials science which make use of the small probe size and thin specimen geometry are the chemical analysis of small precipitates contained within a thin foil and the measurement of chemical concentration profiles near microstructural features such as grain boundaries, point defect clusters, dislocations, or precipitates. Quantitative x-ray analysis of bulk samples using EDS on a conventional SEM is reasonably well established, but much less work has been performed on thin metal foils using the higher accelerating voltages available in TEM based instruments.
Micropatterning of Permalloy Films by Electron Lithography
Authors: Maurin J. K.
Published: June 2020

Conductor, resistor, and dielectric patterns of microelectronic device are usually defined by exposure of a photosensitive material through a mask onto the device with subsequent development of the photoresist and chemical removal of the undesired materials. Standard optical techniques are limited and electron lithography provides several important advantages, including the ability to expose features as small as 1,000 Å, and direct exposure on the wafer with no intermediate mask. This presentation is intended to report how electron lithography was used to define the permalloy patterns which are used to manipulate domains in magnetic bubble memory devices.

The electron optical system used in our experiment as shown in Fig. 1 consisted of a high resolution scanning electron microscope, a computer, and a high precision motorized specimen stage. The computer is appropriately interfaced to address the electron beam, control beam exposure, and move the specimen stage.
Inelastic Electron Scattering from Valence Electrons in Aluminum
Authors: Batson P. E. , Chen C. H. , Silcox J.
Published: June 2020

We wish to report in this paper measurements of the inelastic scattering component due to the collective excitations (plasmons) and single particlehole excitations of the valence electrons in Al. Such scattering contributes to the diffuse electronic scattering seen in electron diffraction patterns and has recently been considered of significance in weak-beam images (see Gai and Howie) . A major problem in the determination of such scattering is the proper correction for multiple scattering. We outline here a procedure which we believe suitably deals with such problems and report the observed single scattering spectrum.

In principle, one can use the procedure of Misell and Jones—suitably generalized to three dimensions (qx, qyand #x2206;E)--to derive single scattering profiles. However, such a computation becomes prohibitively large if applied in a brute force fashion since the quasi-elastic scattering (and associated multiple electronic scattering) extends to much larger angles than the multiple electronic scattering on its own.
Protein Visualization with Crystal Contrast
Authors: Hines R. L.
Published: June 2020

Good contrast can be obtained for unstained protein in biological molecules when the molecules are supported on top of a single crystal film oriented so as to strongly diffract the illumination electrons. If the objective aperture excludes the diffracted beam, the strongly diffracting regions in the crystal film will show up in the image as dark bands a micron or more wide known as bend contours. The bend contour width is determined by the wrinkling of the crystal film which causes local changes in the crystal support film orientation. Biological molecules viewed near bend contours show contrast at exact focus without requiring staining or shadowing with heavy metal atoms. The bend contours are easily moved around by tilting the sample with a tilt stage so that it is not difficult to orient the crystal support so that it is strongly diffracting where ever the biological molecules are located on the support film. The details of the contrast mechanism have been discussed by Hines and Howie.
An Optical Diffraction Study of the Stacking Sequences in Silicon Carbide
Authors: Clarke David R. , Thomas Gareth
Published: June 2020

The basic crystal structure of silicon carbide can be conveniently represented by the close packing of spheres having approximately nearest neighbour interactions, such that each silicon atom is surrounded by four carbon atoms with a tetrahedral coordination and vice-versa. Any observed structure can then be described, by analogy with the close-packed layer stacking in simple face centered cubic structures, simply by the stacking sequence of the close packed planes on the three possible stacking position, A,B, and C, where any one of these layers actually represents a composite of one layer of silicon atoms and one layer of carbon atoms. A consequence of this close packing of spheres with nearest-neighbour interactions is that the energy of the assemblage does not depend on their stacking sequence, and would result in the case of silicon carbide of a structure showing a complete disordering in one dimension.
Resolution Test for the Sem
Authors: Ploc R.A.
Published: June 2020

Many experiments have been proposed for testing resolution in the scanning electron microscope but no standard has been universally accepted.Many investigators have used the smallest separation between two arms of a 50-50% Al-W alloy dendrite as being a measure of resolution but, like other tests, criticism has persisted due to the difference in vertical height between the arms. During the course of our investigations of anodically formed oxides on Zircaloy-2 (a dilute Zr alloy containing 0.05% Ni, 0.1% Fe, 0.1% Cr and 1.5% Sn) a rapid measure of instrument performance was found. The SEM results presented here were obtained on a Coates and Welter CWIKSCAN Model 106A.
Accurate Microcrystallography in the S.E.M. using Electron Backscattering Patterns
Authors: Venables J. A. , Harland C. J. , bin-Jaya R.
Published: June 2020

We have previously shown that electron back-scattering patterns (EBSP) can be observed on a fluorescent screen placed in the specimen chamber of an S.E.M. with the microscope in the spot mode and the angle of incidence > 60°. (1,2). Here we describe methods of determining crystal orientation with 0.5° accuracy using these patterns, and indicate the potential of EBSP's as crystallographic detectors for microscopy at better than 50 nm resolution.

The accuracy of orientation determination using an EBSP is limited by the accuracy with which the position of the emitting point on the specimen is known relative to the screen. By casting geometrical shadows of objects onto the screen this position can be determined. Two types of objects have been investigated, a circular mask and three steel balls. The geometry of the mask arrangement is shown in fig. 1, and an EBSP taken using it is shown in fig. 2;an example using the three ball method is shown in fig. 4. During setting up, these patterns were viewed by closed-circuit TV, and then recorded direct onto 35 mm film.
Characterization of a Fixed Beam Electron Microscope with a Field Emission Gun
Authors: Chiu Wah , Glaeser Robert M.
Published: June 2020

One of the objectives of our research program is to obtain a 2.0 Å point to point resolution in a fixed beam bright field electron microscope. The resolution in the fixed beam electron microscope is limited by a number of factors: electron beam coherence, energy spread, objective lens stability, mechanical stability, and specimen stability. This paper presents systematic studies of the mentioned factors in our JEM 100B fixed beam electron microscope equipped with a field emission gun operating at ∼ 1800°K.

The most important characteristic of a field emission gun is its high brightness in the emitter source. In order to estimate the brightness at the specimen plane, one needs to measure the electron beam current density and the angle of illumination. The electron beam current density has been measured by means of a lithium-drifted silicon detector located below the normal position of the photographic plates. The angle of illumination can be estimated from the size of the condenser aperture and its distance from the specimen plane.
An Interactive Minicomputer Program for the Indexing and Simulation of Electron Diffraction Patterns
Authors: Goehner R.P. , Hatfield W.T. , Rao Prakash
Published: June 2020

Computer programs are now available in various laboratories for the indexing and simulation of transmission electron diffraction patterns. Although these programs address themselves to the solution of various aspects of the indexing and simulation process, the ultimate goal is to perform real time diffraction pattern analysis directly off of the imaging screen of the transmission electron microscope. The program to be described in this paper represents one step prior to real time analysis. It involves the combination of two programs, described in an earlier paper(l), into a single program for use on an interactive basis with a minicomputer. In our case, the minicomputer is an INTERDATA 70 equipped with a Tektronix 4010-1 graphical display terminal and hard copy unit.

A simplified flow diagram of the combined program, written in Fortran IV, is shown in Figure 1. It consists of two programs INDEX and TEDP which index and simulate electron diffraction patterns respectively. The user has the option of choosing either the indexing or simulating aspects of the combined program.
Sample Preparation and Measurement of Losses in Electron Optical Analyses of Particulates in Air and Water Samples
Authors: Lee R. J. , DeBray D. R. , Szirmae A.
Published: June 2020

Electron optical analyses of the type and concentration of particles in air and water samples utilize some method of transferring the particulate material from the collection media to a transmission electron microscope (TEM) grid. The method used represents a significant step in sample preparation and may be the factor limiting the ultimate reliability of the data. We have found that a carbon replication technique in which the collection media (usually a membrane filter) is carbon-coated directly results in no measurable loss during the transfer. The salient features of the technique and a method for direct observation of any losses are described below.

Under normal circumstances the sample received at the Electron Microscope laboratory consists of a membrane filter on which particulates have been deposited. This sample, if lightly loaded, may be prepared in the as-received condition.
Multilevel Methods for Following the Evolution of Structure from Ingot to Sheet
Authors: Park B. K. , Fricke W. G.
Published: June 2020

Most investigations of structure concern themselves with the effect that the final structure in some product has on properties and not on how the structure itself came into being. And yet, the structure of sheet, for example, is profoundly influenced by all steps of fabrication from ingot, through preheat, hot and cold rolling, to final heat treatment. Electronic instruments supplement, or even supplant, the traditional role of the light microscope in following these changes.

Taking aluminum auto body sheet alloy X5020 (2.8% Mg, 1.6% Cu, 0.3% Mn, 0.25% Fe, 0.12% Si) as an example, the evolution of final structure was observed with the scanning and transmission electron microscopes, the image analyzing light microscope, x-ray diffraction and the electron microprobe. Particular attention was paid to intermetallics which have a profound influence on formability and ductility.
Limitation of the use of thin Amorphous Carbon Substrates for High Temperature Microscopy
Authors: Lee Eal H.
Published: June 2020

Carbon films have been used as substrates by many authors at temperatures ranging from 400°-1050°C(1-4). At such high temperatures, however, substrate/ grid interactions become appreciable and the carbon film becomes contaminated, due to carbide formation. Therefore, a series of experiments was performed on the C/Ti, C/Mo, and C/W film/support-grid systems to determine the usefulness of carbon substrates for high temperature TEM applications.

Amorphous carbon films approximately 1000 Å in thickness were prepared using conventional arc evaporation and mounted on Ti, Mo, and W grids. The specimens were then placed in a UHV (∼2xl0-8 torr) electron microscope and observed continuously in-situ during their exposure to temperatures greater than 800°C(5). In this study it was found that carbides formed with all specimens after short times of exposure at 900°C. The micrographs in Fig.
Resistance Monitor and Control for Vacuum Evaporation of Metals and Carbon
Authors: Steere Russell L. , Erbe Eric F. , Michael Moseley J.
Published: June 2020

We have designed and built an electronic device which compares the resistance of a defined area of vacuum evaporated material with a variable resistor. When the two resistances are matched, the device automatically disconnects the primary side of the substrate transformer and stops further evaporation.

This approach to controlled evaporation in conjunction with the modified guns and evaporation source permits reliably reproducible multiple Pt shadow films from a single Pt wrapped carbon point source. The reproducibility from consecutive C point sources is also reliable. Furthermore, the device we have developed permits us to select a predetermined resistance so that low contrast high-resolution shadows, heavy high contrast shadows, or any grade in between can be selected at will. The reproducibility and quality of results are demonstrated in Figures 1-4 which represent evaporations at various settings of the variable resistor.
Some Unique Features in Compound Eyes of Two Isopods
Authors: Nemanic Paula
Published: June 2020

I have observed certain unique features in the ultrastructure of the compound eyes of the terrestrial isopod crustaceans Porcellio scaber and Armadillidium vulgare, using both scanning and transmission electron microscopy.

Only about twenty ommatidia, arranged into four rows, constitute an eye, giving the organ the appearance of a cluster of grapes (Fig. 1). A few trichoid sensilla are interspersed between the ommatidia.

The dioptric apparatus of each ommatidium is composed of a biconvex, cuticular lens and an underlying spherical crystalline cone. In these isopods each crystalline cone is the secretion of only two cells (Fig. 2), rather than four as in most malacostracans. The suture line between the two cone hemispheres is always parallel to the long axis of the ommatidium.
The Development of the Outer Plexiform Layer of the Mouse Retina
Authors: Blanks Janet C. , Adinolfi Anthony M. , Lolley Richard N.
Published: June 2020

In the all-rod retina of the adult mouse, synaptic contacts in the outer plexiform layer occur between photoreceptor terminals and dendritic processes of horizontal and bipolar cells. The postnatal development of the outer plexiform layer has been studied by light and electron microscopy. Following decapitation and enucleation of the eyes, samples of retinae from DBA mice (newborn to fourteen days) were removed and fixed by immersion in solutions of buffered glutaraldehyde and paraformaldehyde. The tissue was postfixed in osmium tetroxide, dehydrated and embedded in araldite. Sections were stained with uranyl acetate and lead citrate.

With light microscopy, the outer plexiform layer first appears in the central retina as a gap within the neuroblastic layer on the fifth postnatal day. The separation is completed by the seventh postnatal day and appears mature by the fourteenth postnatal day.
A Device for Embedding Epon Thick Sections for Electron Microscopy
Authors: Swoveland P. , Baringer J. R.
Published: June 2020

A method has been devised for re-embedding 4-10 micra epon thick sections for thin sectioning. By using this method, multiple areas of a single tissue block are available for examination by electron microscopy without the destruction of deeper levels of tissue during the trimming process.

Section mounting devices have been described by Woodcock and Bell and Ries. Both of these devices are designed to mount several thick sections on epoxy blocks against a single foil-coated microscope slide. However, this requires that several thick sections be available for re-embedding simultaneously. In addition, the sections cannot be observed during the process of flattening them against the microscope slide, and therefore perfect flatness cannot be assured.
Erythrophagocytosis by Entamoeba histolytica.- Ultrastructural Study
Authors: Treviño Norberto , Feria-Velasco Alfredo , de Chávez I. Ruiz
Published: June 2020

Although erythrophagocytosis by various species of Entamoeba is a well known phenomenon this has not yet been studied in detail at the ultrastructural level. The present work deals with the description of the incorporation process of erythrocytes by trophozoites of E. histolytica. For this study, trophozoites of E. histolytica, HK-9:NIH strain cultured in axenic conditions and washed human erythrocytes were placed on a hot plate at 37°C in physiological saline solution. After 5 minutes, 2.5% glutarldehyde was added and the samples were processed according to conventional techniques for electron microscopy.

Based upon light microscopy studies on living trophozoites in contact with erythrocytes, it seems that erythrophagocytosis only takes place in one pole of the parasite.
Fine Structure of Intestinal Epithelia of Earthworm
Authors: Clifford Brendan
Published: June 2020

An ultrastructural investigation of the intestine of the earthworm, Lumbricus terrestris was undertaken as a part of a continuing study of absorptive epithelia.

The earthworm gut is essentially a straight tube extending from gizzard to anus. The epithelia is an unicellular layer which can be regionally differentiated according to apical plasma membrane elaborations. The cells of the anterior 3/4 of the intestine possess microvilli and cilia (whose rootlets converge into bundles white approaching the basal plasma membrane). The cells of the dorsal typhlosole have microvilli but lack cilia while those of the posterior intestinal region possess microvilli, lack cilia and are covered by a well-defined cuticle through which the microvilli extend. The microvilli throughout the intestine (including those which extend through the posterior cuticle) are covered by a glycocalyx.
Electron Microscope Study of RNA's of Paramyxoviruses
Authors: Baum Ruchama , Seto J.T.
Published: June 2020

The ribonucleic acid (RNA) of paramyxoviruses has been characterized by biochemical and physiochemical methods. However, paramyxovirus RNA molecules have not been studied by electron microscopy. The molecular weights of these single-stranded viral RNA molecules are not known as yet. Since electron microscopy has been found to be useful for the characterization of single-stranded RNA, this investigation was initiated to examine the morphology and length measurements of paramyxovirus RNA's.

Sendai virus Z strain and Newcastle disease virus (NDV), Milano strain, were used. For these studies it was necessary to develop a method of extracting RNA molecules from purified virus particles. Highly purified Sendai virus was treated with pronase (300 μg/ml) at 37°C for 30 minutes and the RNA extracted by the sodium dodecyl sulfate (SDS)-phenol procedure.
Geometry of the T-Even Bacteriophage Head
Authors: Gordon C. N.
Published: June 2020

The T-even bacteriophage head is a non-isometric structure composed of more than one kind of protein. The head is assembled in a complex process which involves several products of the phage DNA, and probably the participation of the DNA itself. Two problems which are as yet unsolved are the manner in which the protein subunits are arranged in the mature phage head and the mechanism of head assembly.

There are two conflicting theories regarding the geometrical shape of the head: Moody and Boy de la Tour and Kellenberger consider the head shape to be a bipyramidal pentagonal, antiprism (“prolate icosahedron“); this structure can be thought of as being derived from a head with regular icosahedral symmetry by lengthwise extension of the middle section.
An “Ultrafilter” in the Margo of Mature Bordered Pits?
Authors: Sachs I. B. , Kinney R. E.
Published: June 2020

The micrographs illustrating this paper were obtained from never-dried springwood bordered pit-pairs of Pinus strobus L. Specimens were treated with acidified sodium chlorite in order to remove incrusting materials from the pit membrane. To prevent or reduce interfacial and surface tension forces and provide a view of bordered pit structure without postmortem changes, the specimens were further treated either by the critical point method of Weatherwax and Caulfield, a version of Anderson's method, or by a low temperature evaporation method using molecular sieve material at -40° C. to gently remove the alcohol, Arenberg, et al. For studying the pit membrane of bordered pit-pairs, neither technique seems to have an advantage, giving similar results.

Light and electron microscope studies have established that structurally the bordered pit-pair membrane consists of a torus and a margo.
Mitochondrial Changes in Cholestasis
Authors: Zaki F. G.
Published: June 2020

Alterations of liver cell mitochondria represent pathologic phenomenon of a fundamental nature. Mitochondrial anomalies have been often described in association with cholestasis. In attempt to determine whether a given pattern of mitochondrial alteration has any correlation with the cause of cholestasis, liver biopsies were examined from 38 patients showing :

a. extrahepatic cholestasis due to complete or partial extrahepatic biliary obstruction (8 cases proven at operation)

b. intrahepatic cholestasis due to drugs (9 cases), viral hepatitis (6 cases) and alcoholic cirrhosis (15 cases).

Mitochondria exhibiting ultrastructural changes due to aging or to the ‘wear and teart’ processes were not considered. In this study, the only profound and most prominent mitochondrial deformation was reported on basis of their common occurrence in randomly examined sections.
Human Adenovirus Uptake by Preirnplantation Mouse Embryos
Authors: Chase D. G. , Winters W. , Piko L.
Published: June 2020

Although the outlines of human adenovirus entry and uncoating in HeLa cells has been clarified in recent electron microscope studies, several details remain unclear or controversial. Furthermore, morphological features of early interactions of human adenovirus with non-permissive mouse cells have not been extensively documented. In the course of studies on the effects of human adenoviruses type 5 (AD-5) and type 12 on cultured preimplantation mouse embryos we have examined virus attachment, entry and uncoating. Here we present the ultrastructural findings for AD-5.

AD-5 was grown in HeLa cells and purified by successive velocity gradient and equilibrium density gradient centrifugations in CsCl. After dialysis against PBS, virus was sedimented and resuspended in embryo culture medium. Embryos were placed in culture at the 2-cell stage in Brinster's medium.
Ferritin-Tagging for Group Cross Reactions of Rinderpest, Canine Distemper, and Measles Viruses
Authors: Breese Sydney S. , DeBoer Carl J.
Published: June 2020

The three viruses, rinderpest, canine distemper, and measles are all antigenically related. The viruses in this experiment were all grown in a common host cell, Vero (green monkey kidney), and then each tagged with ferritin conjugated antibody against each. This procedure provided positive identification of each of the virus structures in a heterologous cell system, which did not show non-specific reactions.

The Kabete “O” strain of rinderpest was received from Dr. W. Plowright, East African Veterinary Research Organization, Maguga, Kenya. The canine distemper virus was the Lederle strain (egg adapted) provided by Dr. J.A. Gourlay, National Animal Disease Laboratory (NADL), Ames, Iowa. The measles virus was the Enders strain provided by Drs. Wagner and Seligman, Division of Biologic Standards (DBS), National Institutes of Health (NIH), Bethesda, Maryland.
Particles in the Serum and Liver of a Chimpanzee Infected with Hepatitis Type B
Authors: McGrath Philip P. , Barker Lewellys F. , Chisari Francis V. , Kirschstein Ruth L.
Published: June 2020

Blumberg et al. discovered a new antigen in the blood of an Australian aborigine and subsequently this antigen was found to be associated with viral hepatitis type B (serum hepatitis). Serologic and biochemical changes characteristic of viral hepatitis were induced in chimpanzees by inoculation of human serum containing the Hepatitis B Antigen (HB Ag). The light and electron microscopic findings were essentially the same as those of acute viral hepatitis in man. This report will describe the particles in the serum and liver of one animal from that study.

One milliliter (ml) of the NIH plasma pool which had been shown to contair. HB Ag was inoculated into a 15 lb. chimpanzee.
Artificial Assembly of Genome-Free Hemolytic and Fusion Factors of Sendai Virus (HJV)
Authors: Hosaka Yasuhiro , Shimizu Yohko K. , Shimizu Kazufumi
Published: June 2020

Solubilization of the envelopes of HVJ by treatment with Nonidet P40 caused dissociation of viral protein and lipids. Upon equilibrium centrifugation, the lipids were confined to the top and the viral protein covered two visible bands with hemagglutinating(HA), HI blocking and neuraminidase activities but not hemolytic activity. The solubilized envelopes consisted of free spikes or their aggregates and small granular particles. After removal of the detergent by dialysis, lighter hemagglutinins carrying hemolytic and cell fusion activities appeared. These hemagglutinins looked like fragments of envelopes with typical spikes, which were seen on both the inner and outer surfaces, unlike those of virion envelopes.
A Revised Device for Automated Tissue Processing in Electron Microscopy
Authors: Aihara Kaoru , Saito Hiroshi , Yajima Gompachi , Suzuki Katsuya , Inoue Kiyoko , Nishikawa Hideki , Nakamura Shinichi
Published: June 2020

This is to communicate the technical modification and improvement of the Aihara processor designated for automated tissue processing for electron microscopic histology which has been described previously. At present, in terms of the technical difficulties, the automated tissue processing is not yet widely accepted for practical application.

The present hitherto reported modification of the previous device has been achieved to accommodate the main unit and synchronized thermal and humidity control units in a single frame for the simplification and trouble free operation. The entire view of the device is demonstrated in Fig(1). The basic operational principle utilized in this device is essentially identical with that of hitherto described, however, for more precised operation, tape controlled time programming system as illustrated in Fig(2) is employed.

The elevation of plastic dome is activated by the motor-driven mechanism. The pre-fixation with glutaraldehyde, rinse in buffer solutions postosmification, dehydration in graded alcohols or acetones, soaking in propylene oxide or QY-1, impregnation in epoxy resin are achieved in a single programmed schedule without manual manipulation.
Immuno-Electron Microscopic Study on the Mechanism of Antibody Production inin VitroSystem
Authors: I. Suzuki , T. Takahashi
Published: June 2020

Kamei and Moore reported the specific antibody production of P3-J cell line which has been established from ascites cells of patient with Burkitt's lymphoma, after exposure to T2phage as antigen. P3-J cell line is composed of lymphoblastoid cells and other larger cells, and has ability of immunoglobulin synthesis. The analysis of antibody production by this cell line may offer a model of that of the very complicatedin vivosystem. The present investigation, utilizing the procedure for visualizing intracellular anfibody against horseradish peroxidase, was initiated to know the sequence of cellular events in the P3-J cell line during the production of an antibody after exposure to the antigen.

A human lymphoblastoid cell line, P3-J, was used the present study. This cell line was originally established from ascites cells of patient with Burkitt's lymphoma.
Electron Microscopy of Canine Hepatic Cells in 2-Ethyl-2-Phenyl Butyramideinduced Porphyria
Authors: Zaki F. G. , Keysser C. H.
Published: June 2020

Previous studies in this department with 2-ethyl-2-phenyl butyramide (EPB) have shown that this compound is extremely hepatotoxic in dogs and produces precipitation of yellowish-brown material in hepatocytes and bile canaliculi. Continuous investigations have established that the hepatic injury induced by EPB is porphyria.

EPB was administered orally in capsules to male dogs and to both pregnant and non-pregnant female dogs for periods ranging from 10 to 42 days at a total daily dose level of 50 mg/kg/day.

Light microscopic examination of sections of liver from adult dogs as well as newborn animals from treated mothers showed prominent yellowish-brown deposits in the hepatocytes, bile canaliculi, and sinusoids. These deposits closely resembled the bile plugs commonly seen in cholestasis. However, histochemical tests showed that these “pseudo” plugs contained neither conjugated nor unconjugated bilirubin.

Samples of serum, urine, and bile, as well as slices of liver of dogs given EPB, showed red fluorescence when subjected to ultra-violet light, indicating the presence of porphyrin.
Role of Sub-Micron Particles in Air Pollution
Authors: Bush A. F. , Burke J. P. , Bowler E. S. C.
Published: June 2020

In the decade ahead greater attention to sub-micron particulates in air pollution will most certainly occur. The importance of the electron microscope and support equipment will be invaluable. Airborne particles in the sub-micron size range, detectable only by electronmicroscopy, have been studied at the Air Pollution Research Facility at the School of Engineering and Applied Science at UCLA. Samples were taken of ambient air daily for several months in the downtown area of Los Angeles. From the study it was clear that a substantial difference in the number of sub-micron particles existed when comparing a clear day with a smoggy day. The magnitude was ten fold (0.07 billion particles/cubic foot to 0.7 billion/cubic foot). The geometric mean particle size was approximately 0.03 microns.

Samples were also collected from a variety of specific sources. Most of these were associated with the combustion of fuel: coal, oil, natural gas, gasoline, diesel fuel, wood, and industrial and domestic wastes.
Fine Structural Changes Produced by Benzo(A)Pyrene on Human Respiratory Epithelium in Organ Culture
Authors: Dirksen Ellen Roter , Timothy Crocker T.
Published: June 2020

Earlier studies in this laboratory demonstrated that extensive ultrastructural alterations could be produced as a response to chemical carcinogens in the ciliated columnar epithelium of suckling rat trachea maintained in culture. More recently benzo(a)pyrene (BaP) has also been shown to induce similar pleomorphic fine-structural lesions in hamster respiratory tissues. It was therefore of considerable interest to extend these observations in order to compare these animal model systems of inhalation carcinogenesis with similar studies on human tissues.

Tracheas from four to five month-old fetuses were cultured for 14 days in medium containing 10 μg/ml of BaP dissolved in 1% dimethylsulfoxide (DMSO), while the control tissues were exposed to a similar concentration of DMSO. At this age the tracheal epithelium has achieved a level of cellular and subcellular differentiation closely comparable to that of the adult.

After 14 days in culture the epithelium of the control tracheal explants has maintained its normal architecture.
Thin Metal Film For Electron Microscopic Study of Air Pollutants
Authors: Sakabe H. , Homma K.
Published: June 2020

Waller and others demonstrated the electron micrographs of particles in town air collected on the formvar-coated cover glass. We devised a thin metal film method for electron microscopic study of air pollutants. Since some of the particles collected on thin metal film react on the metal, we can get more information about particles than in case of ordinary membrane. In other words, by thin metal film method, we can see under electron microscope results of chemical reaction between pollutants and metal.

Collodion-coated specimen grid is placed on a cover glass and covered with fume evaporated from metal heated in tungsten wire coil in vacuum evaporator. The thickness of this metal film on collodion membrane is assumed to be about 50-100Å. As for metals, Au, Cu, Ag, Fe, Zn and others are used. The same pollutant gives different figures on different metal films.
Scanning Electron Microscope Induced Cathodoluminescence
Authors: Falk Richard H.
Published: June 2020

Luminescence is a process in which radiation is emitted by molecules or atoms that have been excited by the absorption of radiation. Accelerated electrons have energies very much greater than the quantized levels of atoms and molecules and in passing through a substance, detach bound electrons. A plasma (ion-electron gas) is formed and as recombinations occur, light quanta are emitted. Thus, if one uses accelerated electrons as the source of exciting radiation, observations of cathodoluminescence (CL) may often be made.

Much of the energy absorbed is lost in processes other than luminescence. Losses by internal conversions may occur which involve intersystem crossing from the excited singlet state to the triplet state (phosphorescence or heat) or through predissociation (disruption of chemical bonds in the compound). Energy loss by external conversion (quenching) may also occur through collisions with other molecules (radiationless energy transfer or heat).
Ultramicrotomy and Ultracryotomy in Silicone Polymer and Elastomer Research
Authors: Hulce L. A.
Published: June 2020

Traditionally, the soft resilient silicone polymer and elastomer systems have been thin-sectioned for electron microscopy employing methacrylate embedment techniques for hardening the material. often methacrylate infiltration causes the silicone material to swell--to an extent inversely proportional to the crosslink density of the polymer or elastomer. Therefore, a major difficulty encountered in the embedment of partially crosslinked silicones is the spatial distortion of the ultrastructure due to swelling. Using the method of ultracryotomy, however, the specimen is hardened by cooling below its glass transition temperature and sectioned, eliminating embedment artifacts. Christensen described application of the Sorvall frozen thin sectioner (PTS) to biological specimen preparation at about -75°C. Since silicone polymers exhibit extremely low glass transition temperatures (-125°C for poly(dimethylsiloxane)), they present a very unique challenge in this new area of ultracryotomy. Using the FTS unit on a Sorvall MT-2 ultramicrotome, silicone polymers have been successfully sectioned as thin as 500A in our laboratory.
Current Developments in Cryo-Ultramicrotomy
Authors: Algy Persson K.G.
Published: June 2020

review of cryo-ultramicrotomy covers a rather short period. This preparation method was accepted first at the end of the 1950's and began to be used in the 1960's for technical material such as rubber. It was applicable to elastomers because of their properties at temperatures below glass transition point. Apart from trials in the beginning of the 1950's, the use of cryo-ultramicrotomy for biological material did not really start until the middle of the 1960's.

The instruments for cryo-ultramicrotomy can be divided into three categories, in the order of their complexity, as follows:

1. Cryo-specimen holders, which keep a small part at the end of the specimen arm at low temperature. They give little or no protection to the specimen against frost, the temperature control is difficult and they are rarely combined with cryo-knife holders. Their application is limited to elastomers.
Diamond Knife Defects Observed in SEM
Authors: Temple Black J.
Published: June 2020

In an effort to determine plausible reasons for the failure of diamond knives to perform in ultramicrotomy applications as desired, diamond knife cutting edges were examined in the SEM. An attempt to categorize into type the defects responsible for poor cutting performance or for observable damage to microtomed sections were made so that methods to correct these defects could be properly sought and evaluated. Eight new and used diamond knives were obtained for these studies. The shanks were cut in half and the knives were cleaned with acetone and mounted vertically on a SEM specimen stub. See Fig. 1. Due to SEM contrast, resolution (of edge features) and imaging mechanisms in the secondary mode, it is best to examine the knife edge-on (primary beam perpendicular to edge “E“) and rotated to obtain equal emission levels (going to the collector “C“) from both flanks of the knife.
Thin Film Surface Morphology Visibility (Double Sources of Secondaries)
Authors: Temple Black J.
Published: June 2020

The continued development of commercial STEM systems in the next few years will have a dramatic impact on all aspects of electron microscopy, particularly as the resolution improves. The STEM system offers us the opportunity for direct computer analysis of image signals of all types, wherein signals produced by characteristic X-rays, photons, electrons will be used in a variety of mixes to produce micrographs of thin films. For example, because larger areas and thicker films can be examined in STEM systems compared to CTEM scopes, it will be commonplace to examine sections of thickness cut for OLM transmission work in the STEM. It will also become increasingly important to produce micrographs of matched internal and external structure; that is, internal structure examined by STEM signals and external structure via SEM topographical signals (secondary and backscatter emission). The examination of thin films in the SEM mode however presents some difficulties in that the depth of penetration of the primary beam is a function of the accelerating 1 voltage (roughly according to where k' and n depend on the material).
A Field Emission Gun
Authors: Worsham R. E. , Mann J. E. , Richardson E. G.
Published: June 2020

On theoretical grounds, Welton has shown that with a conventional microscopy Column in which the illuminating wave has a transverse coherence length of ∼1000Å, the micrographs may be processed to extract information fixing the locations of heavy atoms to ∼ 1Å. The method, which involves linear filtering of the Fourier transform and re-transformation to get the corrected image has been illustrated using simulated micrographs. The illumination system shown here in schematic form is part of a so-called “high-coherence” column designed for this method. It consists of a 150-kV field emission gun and a single condenser lens. The remainder of the column, not shown, uses a superconducting objective lens with normal intermediate and projector lens.

The objective operates as a second-zone lens. Therefore a ray bundle entering the lens field parallel to the axis would arrive at the specimen parallel to the axis but reduced in diameter by a factor of 1.41, in this case.
A Comparison of Oxides Grown in Stationary and Moderate Velocity Gas Streams
Authors: Dils R. R.
Published: June 2020

The gas dynamics of many industrial environments induce small fluctuations in the heat flow between the environment and exposed metal surfaces. Temperature fluctuations of the protective metal oxide and metal near the surface of the material result, and, due to the difference in the thermal expansion coefficients of the strongly bound oxide and the metal substrate, shear stress intensities are generated along the weak interface bonds between the metal and the oxide. The oscillatory shear stress intensities fatigue the interface, causing an increase in the rate of oxidation of the material. An example of the effect of the small interface temperature fluctuations on the morphology of the protective oxide is presented in this paper.

Aluminized MarM-200 nickel-base superalloy specimens were oxidized at an average temperature of 2100°F in a stationary gas and in moderate velocity gas streams which induced different temperature waveforms at the interface.
Recent Results in High Resolution Microscopy with Special Apertures
Authors: Thon P. , Willasch D.
Published: June 2020

In bright field high resolution electron microscopy phase plates of varying thickness have been proposed to achieve better phase contrast transfer properties of objective lenses. It was possible to produce these elements by use of a microrecording device and to demonstrate their application in high resolution microscopy. But in order to obtain more favourable results a way of finding the correct phase profile had to be found.

Fig. 1 shows an improved phase plate and its profile. To test the transfer properties of this plate it was used for taking focal series on thin carbon foils. Fig. 2 shows such micrographs together with their light optical Fourier transforms at different defocus values. A broad continuous frequency band is transmitted approximately at the defocus value for which the plate was calculated. It is interrupted only by a small annular zone of reduced transfer due to the edge of the central hole of the phase plate.
Analysis of Integrated Circuits on the Scanning Electron Microscope
Authors: Imai John J.
Published: June 2020

The SEM plays an important role in the performance of failure analyses of Integrated Circuits. As the complexity and density of electrical functions increases on the silicon chip, the more it is nescessary to analyze the detailed characteristics of the failed device. The types of failures of interest are those that have marginal or catastrophic performance characteristics and show no obvious visual defects.

Three aspects of the SEM capabilities will be discussed.

Standard high power magnification operation

Voltage Contrast mode of operation

Emission X-ray analysis operation

Various physical characteristics of an Integrated Circuit can be viewed on the SEM. These characteristics are difficult to view on a high power optical microscope due to the depth of field limitations. These characteristics include the following.

Oxide steps

Metalization profile over oxide steps

Wire bond analysis

Etched metalization characteristics

The Voltage Contrast mode of operation allows direct visual observation of electrical activity on the surface of the silicon chip.
A Comparative Study of Induced-Arc and Resistive Welds Employing SEM and X-Ray Emission Studies
Authors: Saffir Arthur J. , Zenobia Donald I.
Published: June 2020

The purpose of this study was to evaluate the two techniques that are commercially used to bond the components of composite electrical contacts. These materials, usually consisting of a precious metal contacting region bonded to a copper substrate, offer substantial economy compared to similar devices made entirely from precious metals. They also possess unique desirable properties useful in other electronic and biomedical applications. However, these advantages can only be realized if the weld can withstand the severe physical and chemical environment in which it must operate.

The resistive welds are created by bringing the components into contact and then providing a current in order to create sufficient heat for welding. Induced-arc welding requires more operations: the components are held apart with a relative potential of 10 to 100 volts; then they come into contact very briefly, 50 to 500 μsec; they are immediately drawn apart, striking an arc; finally, after arcing from 300 to 3000 μsec, they are forced together percussively while the current continues to flow.
The Structure of Co-Cu-Ce Permanent Magnet Alloys
Authors: Leamy H. J. , Green M. L.
Published: June 2020

Following the discovery by Nesbitt et al that Cu additions to Co5Ce produced an age hardenable permanent magnet of exceptional quality, considerable effort has been devoted to understanding the effect of metallurgical processing on these alloys. Aside from work on the Co-Cu-Sm system, direct observation of the alloy structure responsible for the high coercivity of these alloys has not been reported. Our purpose here is to present a preliminary account of such observations.

The alloy employed in this study was directionally solidified Co3.8FeO.5CuO.9Ce. The boule was spark cut perpendicular to the growth axis into 1 mm thick wafers, sealed under vacuum in quartz ampoules, and heat treated. The wafers were prethinned by electropolishing and profiled by jet polishing in H3PO4 saturated with Cr2O3 at 100°C. During jet polishing the samples were sandwiched between gold grids. Final thinning was accomplished by ion milling.