bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differentiation of Asbestos from Other Minerals by SAED
Authors: Grieger Gene R. 
Published: June 2020

Because of a correlation between exposure to asbestos and the incidence of lung cancer, there has been an increasing emphasis on the identification and measurement of asbestos in air samples, tissues and mineral products. The general method of identifying fibrous asbestos, the form of the mineral used for manufacturing, has been based on morphological features considered characteristic. Recent studies in our laboratories, however, indicate that selected area electron diffraction (SAED) data are often a necessary supplement to morphological data in the differentiation of asbestos fibers from other mineral fibers, particularly in cases involving quantities dòwn to approximately 10-16 g.Our studies have shown a number of similarities between the morphology of asbestos fibers and that of other mineral fibers. At a magnification of 30,000X on the transmission electron microscope, we found dozens of minerals with the 3/1 length-to-diameter ratio which defines a fiber. We observed many metal oxides, typical of foundry fumes, which are similar morphologically to amphibole asbestos fibers.
Dark Field Electron Microscopy for Observing the Atoms in Molecules and Crystals
Authors: Hashimoto H. 
Published: June 2020

The present author and his coleagues showed the arrangement of Th-atoms in long chain molecule (BTCA, benzentetracarboxylic acid) and crystals (ThO2) can be observed in the dark field images of conventional 100 kV electron microscope. They observed the bright spots which are arranged with the expected spacings in the molecules and crystals and have expected image diameters ( ∼ 4 Å) as shown in Fig.1. Since their observation have been carried out by using a microscope with the spherical aberration constant Cs=0.15 cm, which seems to be rather large for obtaining the resolved images of atoms with detectable contrast in the brightfield image, it is desired that certain theoretical interpretation will give the reason why the resolved image can be obtained in the dark field images.Using a theory which is originally developed by Scherzer, dark field images of single atoms and chain of atoms in long chain molecules and crystals have been calculated.
Morphology of γ Precipitates in Ni-Rich γ'-Ni3 (Al,Ta)
Authors: Kear B. H. , Doherty J. E. , Giamei A. F. , Lemaire L. P. 
Published: June 2020

The microstrueture of a commercial nickel-base alloy normally consists of a coherent, cuboidal precipitate of γ’ (alloyed Ni3Al) in a matrix of γ (Ni solid solution). Recently, Ham et al., working with the ternary alloy 78Ni-l8Al-4Ti (a/o), have shown that by appropriate heat treatment a completely novel microstrueture can be developed, in which the matrix is γ’ and the precipitate is platelet γ. The present study represents an extension of this work, and reports some new findings on precipitation of γ in γ’ in alloys similar in composition to the Ni-Al-Ti alloy but with Ta replacing Ti.The alloys used were solutionized in the range 2200-2400°F and aged at l600°F for 24hrs (giving ∼ 10 vol. percent of γ in γ’). According to our most recent findings, unlike the binary system, the solubility of γ’ for γ reaches a maximum at ∼ 2200°F in these alloys.
A Diffraction Contrast Study of Displacement Faults in an Ordered Ni-Al-Ti Alloy
Authors: Strutt P. R. , Ingram J. C. , Polvani R. S. 
Published: June 2020

A study has been made of Ni-Al-Ti alloys with compositions along the tie-line between the β-NiAl and Ni2AlTi phases; Ni2AlTi has the Heusler-type structure. The micrographs in Figs. 1-4 are from an alloy with composition 63.8 wt% Ni, 20.5 wt% Al, and 15.6 wt% Ti. A fine precipitate forming a “tweed” or modulated structure was observed (see Figs. 2, 3, and 4), and in the diffraction pattern strong Heusler ordering reflections were evident. of particular interest are the unusual displacement faults, which unlike those observed by Ball in Al-rich NiAl generally do not lie in specific crystallographic planes, but are high convoluted as shown in Fig. 1.In Fig. 2 each fault in the array A to B terminates at a dislocation, and it was deduced that these dislocations had a ao[001] Burgers vector since they were invisible when g = [110], and [200].
A New Low-Cost Image Intensifier for Transmission Electron Microscopy
Authors: Heinemann Klaus , Poppa Helmut 
Published: June 2020

An efficient electron microscope image intensifier (EMII) chain with closed-circuit television image display should feature the following characteristics:- The signal of a single incoming electron should be raised well above the equipment noise.- The spatial resolution of the EMII-chain should not be worse than the product of available electron optical magnification and the desired specimen resolution.- The spatial resolution of the TV-system, multiplied by the magnification factor between the intensified image and its size on the camera tube face, should not be better than the spatial resolution of the image intensifier (the lowest reasonable bandwidth should be selected).In this paper we present a new type of EMII system which fulfills these basic features within the framework of a comparatively high performance-to-cost ratio system. We have been using two medium-resolution microchannelplates in series as an image intensifier (resolution approximately 50 microns), featuring a gain of more than 106with practicably negligible noise.
Preliminary EM6 Modifications for in situ Chemical Vapor Deposition
Authors: Kenty J. L. 
Published: June 2020

An AEI EM6 electron microscope is being modified for in situ chemical vapor deposition. The objective is to observe the nucleation and growth kinetics and structure of silicon deposited by SiH4 gas pyrolysis on substrates of sapphire (single crystal α-Al2O3).An Edwards DCB2 thermoelectrically cooled baffle has been installed using a simple adapter which permitted attachment without drilling or cutting of the EM6 frame or vacuum system. Prior to installation the measured contamination rate was 240Å/min; afterward the contamination rate was less than 100 Å/min.An auxiliary pumping system is mounted to the left rear of the column and attached by a special stainless steel flexible bellows to the pumping port at the rear of the specimen chamber. The auxiliary system has an ultimate presure <1 × 10-6 torr, but the measured pressure in the specimen chamber was no better than 1 × 10-5 torr, due primarily to the high outgassing rate of the beam deflector coil immediately above the specimen chamber.
Diffraction Analysis by Computer
Authors: Ploc R.A. 
Published: June 2020

Several computer programs have been written recently to aid in analysing electron diffraction data. A summary of these programs and the manner in which they inter-relate will be given.The programs are called, PATTERN, SADSP, RING, STEREO and CCRYS, the functions of which are; to calculate and plot simulated SAD spot patterns, to analyse spot and ring data, to produce stereographic projections and to calculate structure factors respectively. Acquisition of the programs should be through written request to the author.By the application of the programs SADSP and RING it will be shown that effective chemical identification of small amounts of material can be performed in the TEM. For instance, small acicular growths formed on the inside of a high-pressure water loop containing radio-active materials have defied conventional analysis because of their small size (200 Å thick, 1-3 μm long and high) and location (on the surface of a “crud”deposit).
A HVEM and SEM Study of Elongation Rate Effects on Fracture Mechanisms in Ag Crystals
Authors: Lyles R.L. , Wilsdorf H.G.F. 
Published: June 2020

The application of high voltage electron microscopy, combined with the ability to record dynamic phenomena, represents a most effective means of studying the microstructural mechanisms of fracture by direct observation. Using techniques described previously, the University of Virginia's 500 kV electron microscope has been utilized for in situ investigations of phenomena occurring during crack propagation. Chemically grown, (111) <110> single crystal silver ribbons (.5-2μ thick,.5-1 mm wide, and 3-5 mm long) were strained to fracture at elongation rates of 102Å/sec, 103Å/sec, and 104−105Å/sec. in a precision straining stage.The orientation of the tensile specimens was such that the (111) plane was normal to the electron beam while the tensile axis was aligned with the [011] direction. Accordingly, when the crystals were strained, a 30° lattice rotation around the [111] pole resulted in the initial <110> tensile axis reorienting to a <112> direction. The failure of the specimens occurred under this new orientation.
Depth Distribution of Defect Clusters in Electron Irradiated Aluminum Films
Authors: Rao Prakash 
Published: June 2020

The possibility of creating displacement damage by electron irradiation of materials in the high voltage microscope has led to several recent studies of the nature and growth of point defect clusters created by such irradiation (e.g. Ref. 1). A study of the depth distribution of such defect clusters is of interest since the film surfaces, surface contaminants, dislocations and grain boundaries should control the size and may even influence the nature of these clusters. In such cases, stereoscopic viewing has the advantage that defect densities can be measured locally and as a function of depth in the specimen rather than as an average over the film thickness.Polycrystalline aluminum films 6250Å thick were evaporated onto cleaved rock salt substrates held at 350°C under a vacuum of 10−8 Torr. The films were irradiated at room temperature in the Berkeley 650kV electron microscope to a total dose of 6.6×l022 electrons/cm2 corresponding to 17.4 displacements/atom.
The Interaction of Fast Electrons with Aromatic Amino Acids
Authors: Lin Paul Shau-Da 
Published: June 2020

As part of a program in investigating the interaction of electrons with biological molecules in a field emission scanning microscope, we have studied the energy loss spectra of aromatic amino acids: Tryptophan, Tyrosine and Phenylalanine.The instrument used is the simple multipurpose scanning microscope previously constructed. The high resolution magnetic spectrometer installed in this microscope enables a resolution of ∽.2 ev as limited by the energy spread in field emission only.The energy loss spectra of Tyrosine and Tryptophan are shown in Figs. 1 and 2. In general, they consist of several peaks below ∼l0 ev, a broad one around 25 ev, and some shoulders on the broad peak. The structure below ∽10 ev bears close correlation with UV, far UV or synchrotron radiation spectra, and can be deduced from each other by Kramers-Kronig transformation. For biological specimens, this has more recently been demonstrated for Nuclei-Acid Bases.
Radiation Damage Study of Crotoxin Complex Crystal at 4K and 300K
Authors: Chiu W. , Knapek E. , Jeng T.W. , Dietrich I. 
Published: June 2020

Radiation damage is the most fundamental problem in the structural study of biological and organic materials by electron microscopy. Low dose technique has been rather successful to record images of beam sensitive biological crystals out to 5-7Å resolution at room temperature. However, if the specimen is kept at low temperature, the effect of radiation damage would be reduced and it will enhance the feasibility of recording images of biological crystals beyond this resolution limit. We have investigated the radiation damage kinetics of crotoxin complex thin crystal embedded in glucose at both 300K and 4K.The room temperature experiment was conducted with a JEM100CX electron microscope at 100kV, and the low temperature experiment was conducted with the superconducting lens microscope at 220kV, built in Siemens. The experimental method was to record a successive electron diffraction pattern from the same crystal at increasing accumulated doses. These patterns were then digitized with a Perkin Elmer microdensitometer and the intensities of each reflection were integrated with the background being subtracted.
Microstructure of Vanadium-Oxygen Alloys
Authors: Lawless K. , Kenik E. A. , Bentley J. 
Published: June 2020

The present study is a continuation of our investigation on in situ oxidation of vanadium and vanadium-titanium alloys. Vanadium is a reactive metal and forms a large number of oxides during high-temperature exposure to oxygen. The microstructure of the oxides formed during the first stages of oxidation and the transformations between oxide phases are under investigation.Single crystal specimens were oxidized in situ using the ORNL Hitachi HU-1000 high voltage electron microscope (HVEM). Both total pressure and residual gas composition were monitored during the experiments. In addition to in situ HVEM observations, high resolution lattice imaging and convergent beam electron diffraction were performed in JEOL 120CX and Philips EM-400T/FEG analytical electron microscopes (AEM).During exposure to oxygen, the transformation to oxide occurs first in the thinnest regions of the foil where the concentration of absorbed oxygen is highest. As oxidation proceeds, the transformation zone moves into thicker regions of the foil.
Point Defect and Interface Imaging at the Atomic Resolution Level
Authors: Krakow W. , Tan T.Y. , Foell H. , Cherns D. , Smith D.A. 
Published: June 2020

The ultimate goal of high resolution electron microscopy is to obtain a structure image which is representative of the atomic arrangement of a thin film. The problem in achieving this goal is two-fold involving: (1) the diffraction mechanisms of the specimen of interest (structure, orientation, inelastic scattering, thickness) and (2) the modification of the diffracted waves by the microscope electron optics (aberrations, beam tilt and divergence). These two difficulties are often intermixed with one being a direct consequence of the other. Several authors have considered some of these effects for perfect crystalline structures which include those of tungsten bronze. Si and Ge. Axial illumination has been the standard imaging mode for these investigations since only a radial contrast transfer function need be considered. The analysis of data from micrographs has been simplified by considering a discrete or small number of Bragg beams at specific reciprocal space positions.The analysis of images of defects requires a more detailed knowledge of the reciprocal space scattering distribution of a specimen which includes the diffuse scattering. Hence, a full two dimensional map of the phase shifts introduced by the microscope optics is needed. The two main classes of defects which will be considered for crystalline materials are: (1) point defect rows and (2) intercryslalline interfaces. The main reason for classifying an interfacial region separately that scattered waves from different crystal phases or crystal orientations on each side of the boundary can extend into the other and complicate image interpretation.
Digital Processing of STEM Images
Authors: Crewe A. V. , Ohtsuki M. 
Published: June 2020

We have assembled an image processing system for use with our high resolution STEM for the particular purpose of working with low dose images of biological specimens. The system is quite flexible, however, and can be used for a wide variety of images.The original images are stored on magnetic tape at the microscope using the digitized signals from the detectors. For low dose imaging, these are “first scan” exposures using an automatic montage system. One Nova minicomputer and one tape drive are dedicated to this task.The principal component of the image analysis system is a Lexidata 3400 frame store memory. This memory is arranged in a 640 x 512 x 16 bit configuration. Images are displayed simultaneously on two high resolution monitors, one color and one black and white. Interaction with the memory is obtained using a Nova 4 (32K) computer and a trackball and switch unit provided by Lexidata.The language used is BASIC and uses a variety of assembly language Calls, some provided by Lexidata, but the majority written by students (D. Kopf and N. Townes).
Amorphous Phase Separation in Vapor-Quenched Cu-Zr
Authors: Marshall A. F. , Walmsley R. G. 
Published: June 2020

Noncrystalline Cu-Zr alloys can be formed by liquid or vapor quench techniques over a wide range of compositions. These noncrystalline structures are typically homogeneous. We have recently observed a microstructure apparently composed of two amorphous phases in noncrystalline sputter-deposited Cu-Zr at a composition of 40 at% Zr. The occurrence of two amorphous phases in this material was also indicated by x-ray diffraction, differential scanning calorimetry, and electrochemical measurements. The purpose of this paper is to confirm and characterize the two-phase microstructure using the analytical electron microscope.The CuZr films were formed by magnetron sputter deposition in a phase spread mode, i.e., separated Cu and Zr sputtering sources producing a range of compositions on the static substrate. TEM specimens at the composition 40 at% Zr were prepared by ion milling. It was necessary to mill at very low beam currents to avoid excessive heating of the specimen and consequent changes in the microstructure.
A TEM Study of the Evolution of Strain-Induced Martensite
Authors: Staudmanner K. P. , Murr L. E. , Hecker S. S. 
Published: June 2020

We have demonstrated previously the effects of strain, strain state, strain rate, and temperature on the morphology of strain-induced martensite in type 304 stainless steel. In all cases α' martensite nucleated at shear band intersections as suggested by Olson and Cohen, but the final morphologies were different. As the amount of martensite increased (with increasing strain, biaxial tension, low strain rates, and low temperatures), α' appeared more blocky and less lath-like. We have demonstrated that α' embryos grow by coalescence of new embryos, rather than actual growth.In the present study, we concentrated on the early stages of transformation to determine if α' embryos are identical for test conditions including uniaxial tension, biaxial tension, and shock loading, at room and cryogenic temperatures (as detailed in the caption of Fig. 1). Strain levels were controlled to produce only small amounts of α'. Sheet specimens, 0.18 mm thick, were used for all experiments, thinned to electron transparency, and examined in a JEOL 200B microscope operated at 200 kV.
Dual Ferrite-Martensite Treatments of an ASTM A588 HSLA Steel
Authors: Chen L.J. , Yang J.R. 
Published: June 2020

During the past several years duplex ferrite-martensite (DFM) steels have received increasing attention for improved strength and weight applications, since they contain characteristic microstructural features that combine high strength with good formability. ASTM A588 is one of the most widely used classes of high strength low alloy (HSLA) steels. It possesses the atmospheric corrosion resistance property as well as relatively high yield strength (∼35 kg/mm2) in the normalized condition. DFM treatments has been applied to the A588 steel.The treatments consisted of initial austenitization and quenching to form 100% martensite, followed by annealing in the (α+γ) region at different temperatures and subsequent quenching. The DFM structure samples were also tempered at 200°-600°C for one hour. Phase diagram of a model steel and the schematic of treatments are shown in Figs. 1(a) and 1(b), respectively. Hardness, ultimate tensile strength, yield strength, elongation and Charpy impact values were measured for thermally treated samples.
High Resolution Dark Field of Poly(p-Phenylene Benzobisthiazole)
Authors: Minter J.R. 
Published: June 2020

The resolution attainable in polymer samples is limited by radiation damage causing crosslinking or chain scission with subsequent loss of mass. Molecules containing aromatic groups have been found to have improved resistance to beam damage, presumably due to resonance stabilization of radicals generated by the electron beam. Poly(p-phenylene benzobisthiazole) (PBT), a wholly aromatic, heterocyclic polymer used in high modulus, high strength fibers and films has been studied by tilted beam dark fieldSamples thin enough for TEM were prepared from bulk films by extraction replication with collodion and examined in a JEOL 100 CX operated at 100 KV using Kodak 4463 film. Figure 1 shows the decay of the 2nd, 3rd and 4th equatorial reflections as a function of electron dose. The intensity was assumed to be proportional to the current on the isolated observation screen when the microscope was operated in the diffraction mode and the appropriate reflections selected with a 2.8 mrad objective aperature (see Figure 1).
Improved Virus Particle Counting by Direct Sedimentation onto EM Grids
Authors: Miller Mahlon F. , Rdzok Edward J. 
Published: June 2020

Investigators who have attempted to sediment virus particles directly onto EM grids have reported problems with: a) tearing of plastic support films covering grid openings, b) uneven distribution of virus due to depression of support films in grid openings during ultracentrifugation, c) failure of sedimented and stained particles to adhere to support films, and d) lack of uniformity of negative stain. The design of a new particle counting rotor and its use in preparing particulate specimens for counting by either the pseudoreplication or thin section methods was previously reported. In the present communication, a simple and reliable procedure is described in which this rotor is utilized to sediment virus particles directly onto grids for counting. The rotor (Fig. 1) operates in the Beckman AirfugeTM tabletop ultracentrifuge.In preparation for counting, 500 mesh copper grids are sandwiched between parlodion support films and 5 mm2 Millipore filter squares (Fig. 2) which conveniently holds grids in a vertical position at the base of sector cells in the rotor core (Fig. 1).
Mapping the Ribosomal Exit Site of the Nascent Polypeptide Chain by Immune Electron Microscopy
Authors: Bernabeu Carmelo , Lake James A. 
Published: June 2020

Immune electron microscopy is providing information on the three dimensional locations of many functional sites on the ribosome. In particular, localization of the exit site of the newly synthesized protein chain is expected to provide information on the mechanisms of protein synthesis and on the nature of the ribosome-membrane association. Theoretically the nascent chains of the largest proteins could be visible as they leave the ribosome, but in practice they have not been observed. In order to map their exit site we have made antibodies against one particular enzyme and then applied immune electron microscopy to a polysome fraction enriched for that special protein.In a mutant of Escherichia coli constitutive for the enzyme beta-galac- tosidase, this enzyme accounts for approximately 25% of the total protein (1). Because of the high molecular weight of beta-galactosidase, a fraction of larger polysomes, further enriched in this emzyme, was obtained by differential centrifugation. When IgG antibodies against this enzyme are reacted with polysomes, two types of profiles are observed.