bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a Rapid Survey Method of Sampling and Analysis for Asbestos in Ambient Air
Authors: Heffelfinger R. E. , Melton C. W. , Kiefer D. L. , Henry W. M. , Thompson R. J. 
Published: June 2020

A methodology has been developed and demonstrated which is capable of determining total amounts of asbestos fibers and fibrils in air ranging from as low as fractional nanograms per cubic meter (ng/m3) of air to several micrograms/m3. The method involves the collection of samples on an absolute filter and provides an unequivocal identification and quantification of the total asbestos contents including fibrils in the collected samples.The developed method depends on the trituration under controlled conditions to reduce the fibers to fibrils, separation of the asbestos fibrils from other collected air particulates (beneficiation), and the use of transmission microscopy for identification and quantification. Its validity has been tested by comparative analyses by neutron activation techniques. It can supply the data needed to set emissions criteria and to serve as a basis for assessing the potential hazard for asbestos pollution to the populace.
“Preparation of Single Crystalline Gold Films for ED Studies”
Authors: Peng Joseph D. C. 
Published: June 2020

The relative intensities of the ED spots in a cross-grating pattern can be calculated using N-beam electron diffraction theory. The scattering matrix formulation of N-beam ED theory has been previously applied to imperfect microcrystals of gold containing stacking disorder (coherent twinning) in the (111) crystal plane. In the present experiment an effort has been made to grow single-crystalline, defect-free (111) gold films of a uniform and accurately know thickness using vacuum evaporation techniques. These represent stringent conditions to be met experimentally; however, if a meaningful comparison is to be made between theory and experiment, these factors must be carefully controlled. It is well-known that crystal morphology, perfection, and orientation each have pronounced effects on relative intensities in single crystals.The double evaporation method first suggested by Pashley was employed with some modifications. Oriented silver films of a thickness of about 1500Å were first grown by vacuum evaporation on freshly cleaved mica, with the substrate temperature at 285° C during evaporation with the deposition rate at 500-800Å/sec.
A Many-Beam Technique for Enhanced Resolution of Partial Dislocations
Authors: Oblak J. M. , Kear B. H. 
Published: June 2020

The “weak-beam” and systematic many-beam techniques are the currently available methods for resolution of closely spaced dislocations or other inhomogeneities imaged through strain contrast. The former is a dark field technique and image intensities are usually very weak. The latter is a bright field technique, but generally use of a high voltage instrument is required. In what follows a bright field method for obtaining enhanced resolution of partial dislocations at 100 KV accelerating potential will be described.A brief discussion of an application will first be given. A study of intermediate temperature creep processes in commercial nickel-base alloys strengthened by the Ll2 Ni3 Al γ precipitate has suggested that partial dislocations such as those labelled 1 and 2 in Fig. 1(a) are in reality composed of two closely spaced a/6 <112> Shockley partials. Stacking fault contrast, when present, tends to obscure resolution of the partials; thus, conditions for resolution must be chosen such that the phase shift at the fault is 0 or a multiple of 2π.
Effect of Prior Microstructure on Neutron Damage in Stainless Steel
Authors: Laidler J.J. , Mastel B. 
Published: June 2020

It has been found that cold-working prior to irradiation reduces the tendency for void formation in austenitic stainless steels irradiated to high fast neutron fluences at elevated temperatures. Reductions in cross-sectional area of the order 20%, for example, result in an order-of-magnitude decrease in the volume expansion of Type 316 stainless steel at fluences of about 3 x 1022 n/cm2. Little is known about the mechanism whereby the reduction in volume expansion is achieved, but it is generally assumed that the increased dislocation density in cold-worked stainless steel simply provides an increased concentration of sinks for point defects.Foil specimens of Type 316 stainless steel were solution-annealed at 1100°C and then strained in tension 0.5, 1, 2, 4, 6, 10, and 15% Disc specimens 3mm in diameter were punched from the strained foils, the discs were coded and then encapsulated in helium-filled capsules. The capsules were irradiated in EBR-II at a temperature of 425°C to a fluence of 2.0 x 1022 n/cm2 (E > 0.1 MeV). The irradiated specimens were examined with the HEDL JEM- 1000 electron microscope at an accelerating voltage of 1,000 KV.
Effect of Accelerating Voltage and Specimen Temperature on Radiation Damage of Hexadecachloro Copper Phthalocyanine
Authors: Harada Y. , Taoka T. , Watanabe M. , Ohara M. , Kobayashi T. , Uyeda N. 
Published: June 2020

In order for the single atoms in organic molecules to be resolved, considerably high magnification would be needed up to 100 to 200 thousand times. A highly bright illumination of electron beam is an essential requirement for this purpose, consequently giving rise to the serious problem of radiation damage. In the course of electron microscopy of organic crystals in respect to their epitaxial growth, it was found that Cuhexadecachloro-phthalocyanine (Cu-Cl16PC), which is wholly chlorinated Cu-phthalocyanine (Cu-PC), is remarkably resistant to radiation damage. This report is to show semiquantitatively the resistivity of the materials against the beam at various accelerating voltages and different specimen temperatures.The specimen were thin crystalline films of Cu-PC and Cu-Cl16PC (Fig.1), all being prepared through epitaxial growth in an ultra high vacuum evaporator. The film thickness was carefully controlled to 200-300A by the use of a quartz crystal oscillator microbalance. The films were supported on carbon microgrid with small holes 1 or 2 microns in diameter as shown in Fig.2.
Re-Embedding of Specimens for Maximum Orientation
Authors: Brundage Margot , Dunn Robert F. 
Published: June 2020

Re-embedding of plastic impregnated tissue blocks is easily accomplished when a combination of carnuba and Tenax dental waxes is used. This method is particularly helpful when combined with capsule flat end embedding, because the entire orientation range of the microtome can be utilized for final exact positioning of the specimen. A demonstration of both techniques will be given.The advantages of re-embedding are: 1, complete freedom in orientation of the tissue, and 2, multiple segments of the same block can be used for various orientations. Re-embedding involves: 1, removal of a tissue block from the surrounding plastic (Fig. 1), and 2, orientation and embedding of the tissue into wax which has suitable support properties for sectioning.Equipment and materials needed for re-embedding include: dissecting microscope; wax mixture ( carnuba 35%, Tenax 65%); empty gelatine capsules; dental carvers; dissecting needles; #7 Dupont forceps; Pasteur pipettes; specimen holders; razor blades; and gas flame.
The Application of Atom-Probe Techniques in Materials Science and Technology
Authors: Ralph Brian , Waugh A.R. , Hill S.A. , Southon M.J. , Thomas M.P. 
Published: June 2020

This brief review attempts to summarize the main uses to which the atom-probe field-ion microscope and its variants have been put in the examination of materials. No attempt is made to produce a comprehensive list of all the studies made to date, rather the type of application is illustrated from recent studies.The original form of the field-ion microscope was really limited to the acquisition of geometrical and crystallographic information on the fine scale distribution of defects and phases (e.g. 1). Even in these early applications, the study proved considerably more fruitful when other microstructural techniques, such as transmission electron microscopy, were applied in parallel. The advent of the atom-probe (AP) and imaging atom-probe (IAP) instruments allowed precise microchemical information to be obtained and these instruments have now been used for a number of detailed investigations of materials. In the main, these have divided into (I) studies of surface process and films (e.g. 2) and (II) investigations of phase distributions and segregation in the bulk (e.g. 3).
Radiation Damage of Support Films
Authors: Cohen H.A. , Chiu W. 
Published: June 2020

The goal of imaging the finest detail possible in biological specimens leads to contradictory requirements for the choice of an electron dose. The dose should be as low as possible to minimize object damage, yet as high as possible to optimize image statistics. For specimens that are protected by low temperatures or for which the low resolution associated with negative stain is acceptable, the first condition may be partially relaxed, allowing the use of (for example) 6 to 10 e/Å2. However, this medium dose is marginal for obtaining the contrast transfer function (CTF) of the microscope, which is necessary to allow phase corrections to the image. We have explored two parameters that affect the CTF under medium dose conditions.Figure 1 displays the CTF for carbon (C, row 1) and triafol plus carbon (T+C, row 2). For any column, the images to which the CTF correspond were from a carbon covered hole (C) and the adjacent triafol plus carbon support film (T+C), both recorded on the same micrograph; therefore the imaging parameters of defocus, illumination angle, and electron statistics were identical.
Crystal Packing ofE.ColiPorin (Matrix Protein)
Authors: Dorset D.L. , Engel A. , Garavito R.M. , Rosenbusch J.P. 
Published: June 2020

Porin, a pore-forming protein spanning the outer membrane of E. coli (MW 36,500) has been isolated in homogeneous form after extraction in detergent. Electrical measurements on planar lipid membranes containing this protein indicate that it may be regarded as a paradigm of pore-forming transmembrane proteins. Therefore, a structural elucidation appears to be useful for correlating the pore geometry with the electrical measurements.Extraction of cells with ionic detergents, with or without removal of the peptidoglycan layer, has been monitored by Steven et al. using high resolution electron microscopy. Optical and computer reconstructions of the images indicated a trimeric structure packing in plane group p3 (a = 77 Å). Three dense patches of negative stain were tentatively assigned to the pores, an arrangement corroborated later by strong interactions among triplet channels observed in the conductance studies.
Microstructural Studies of Laser-Melted Titanium-Rare-Earth and Titanium-Boron Alloys
Authors: O'Neal J. E. , Peng T. C. , Sastry S. M. L. 
Published: June 2020

The feasibility of producing super-saturated solid solutions with small grain sizes and fine, stable, incoherent dispersoids was determined in laser-surface-melted Ti-rare-earth (RE) (RE = Er, Y, Gd, Nd, or Sc) and Ti-B alloys. Titanium specimens, coated with 0.02 to 1-μm thick electron-beam-evaporated rare-earth metal films or with a 10 to 25-μm thick boron slurry, were surface melted using a 1.5 kW continuous-wave CO2 laser beam at specimen traversing speeds of 0.5 to 40 cm/s. The microstructures of the laser-melted regions, determined by scanning and transmission electron microscopy, were correlated with the laser-processing parameters.Figures 1a-1c are scanning electron micrographs of transverse sections of the laser-melted Ti-Y alloy at traversing speeds of 0.5, 10, and 30 cm/s respectively. The positions of the solid-liquid interfaces match the theoretically predicted melting isotherms for a specimen-beam coupling efficiency of 25%. Constant cooling-rate curves, calculated from the heat-transfer model for a rapidly moving, high-power, Gaussian source, are included in Figures 1a-1c. In the laser-melted Ti-RE alloys with the 0.2-μm thick rare-earth films, the microstructure consists of fine 10-20 nm dispersoids. The dispersoid size decreases with increasing specimen traversing speed as well as with increasing distance from the specimen surface. The volume fraction of the dispersoids increases with increasing film thickness and with melt depth. The equilibrium, coarse, constituent particles, which are generally observed in conventionally cast Ti alloys containing corresponding amounts of rare-earth elements, were completely absent in the laser-melted alloy.
Nucleation and Growth of Oxides on Iron
Authors: Kuroda K. , Mitchell T. E. 
Published: June 2020

The growth of oxide nuclei on iron has been investigated both in situ and ex situ by electron microscopy using a Hitachi HU-650B HVEM and a Philips EM400T. Thin specimens of large grained polycrystalline 99.99% Fe were electrochemically polished and oxidized at temperatures in the range of 600 to 700°C and 10-5 torr air. At high temperatures (>600°C), it is well known that wustite (Fe1-xO) , magnetite (Fe3O4) and hematite (αFe2O3) form on iron. Previous TEM work (1) indicates that wustite and magnetite have a fixed epitaxy with (001) parallel to the iron substrate in the early stages of oxidation.The shapes of oxide nuclei are often irregular with straight edges: triangular, rectangular and hexagonal, and sometimes circular. Figure 1 shows numerous oxide islands formed in situ at 650°C in the microscope column vacuum of 2 x 10-5 torr air. Black/white strain contrast observed across an island indicates that formation of oxide nuclei is similar to the nucleation of coherent precipitates on the surface.
Oxide Microstructure and Composition in Fe-Cr Alloys
Authors: Labun P. A. 
Published: June 2020

Microstructure and microchemistry of oxides in Fe-Cr alloys have been investigated with a Philips EM400T equipped with an energy dispersive x-ray detector and a secondary electron detector.Cold-rolled strips of Fe-Cr with 3, 9, 12, 18 wt.% Cr were vacuum annealed, electropolished to a thickness of about 0.1mm and punched into 3mm discs. Some of these discs were jet-polished for low pressure oxidation studies while other discs were oxidized first and then back-thinned. Pressures of 10-5 Torr (air) and 20 Torr (dry O2) were used at oxidation times of 5 and 30 minutes at temperatures in the range of 600° to 800°C.Microstructures characteristic of alloys oxidized at the lower pressure (10-5 Torr of air) is shown in Fig. 1. Rectangular shaped light patches are seen in the alloys containing higher than 9%Cr. Energy dispersive analysis on these light patches gave high Cr concentrations relative to the starting matrix. When the electron beam was placed on the dark areas, quantitative analysis revealed concentrations the same as in the bulk alloy.
Analytical Electron Microscopy Characterization of Electric Arc Furnace Dust
Authors: Porter J. R. , Goldstein J. I. , Williams D. B. 
Published: June 2020

Alloy scrap metal is increasingly being used in electric arc furnace (EAF) steelmaking and the alloying elements are also found in the resulting dust. A comprehensive characterization program of EAF dust has been undertaken in collaboration with the steel industry and AISI. Samples have been collected from the furnaces of 28 steel companies representing the broad spectrum of industry practice. The program aims to develop an understanding of the mechanisms of formation so that procedures to recover residual elements or recycle the dust can be established. The multi-phase, multi-component dust particles are amenable to individual particle analysis using modern analytical electron microscopy (AEM) methods.Particles are ultrasonically dispersed and subsequently supported on carbon coated formvar films on berylium grids for microscopy. The specimens require careful treatment to prevent agglomeration during preparation which occurs as a result of the combined effects of the fine particle size and particle magnetism. A number of approaches to inhibit agglomeration are currently being evaluated including dispersal in easily sublimable organic solids and size fractioning by centrifugation.
Transmission Electron Microscopy of Fine Powder Samples
Authors: Koch E. F. , Walter J. L. 
Published: June 2020

There is increasing interest in the possible use of parts fabricated from fine powders of metallic alloys for structural purposes because of possible improvements in strength both at low and high temperatures. Since powders can experience very high solidification rates, alloys prepared in powder form by rapid quenching may achieve a degree of homogeneity not obtainable by any other means. Also, these high solidification rates might make it possible to produce amorphous powders.Determination of the microstructures of such powders may require transmission electron microscopy of either replicas or thin foils. This report describes a relatively simple method of preparing thin foils of powders, and illustrates the microstructures of fine powders of a nickel-base superalloy and of an amorphous alloy. The method involves incorporating the powders into a metal matrix, and thinning matrix and powder by ion-milling or by electropolishing.
In-Situ Formation of Clean, Single Crystal, and Electron Transparent Sapphire Substrates
Authors: Heinemann K. , Anton R. , Poppa H. 
Published: June 2020

The availability of clean and thin substrates with micron-size single crystalline areas and a low defect density is a prerequisite for meaningful in-situ TEM epitaxial nucleation and growth studies. We are now reporting two related techniques for producing such electron transparent films of α-Al2O3 (sapphire). They have the added advantage of exhibiting grains of various crystallographic orientations.A 1000 Å thick film of amorphous Al2O3, obtained by electrolytic oxidation of aluminum foil and subsequent chemical separation from the metal, was mounted on a 200 mesh W grid in the hot stage of the uhv specimen chamber of a 100 KV TEM equipped for in-situ experimentation. Electron-beam flash-heating with a 5-50 μm diameter beam at several A/cm2 current density (by removing the condenser 2 aperture and turning condenser 1 off) produced sapphire regions of 5-100 μm in size with several large grains. The size of the recrystallized areas increased with increasing duration of the flash (0.1 sec. to 1 sec.) and increasing beam current and diameter. According to Chang and our in-situ nucleation results with metal deposits, the sapphire surface is atomically clean after such high temperature treatment. The example of Fig. 1 shows recrystallization to a single grain. Thermal preheating of the amorphous film up to 800°C produced very fine polycrystalline Al2O3, but had no apparent effect on the result of subsequent e-beam recrystallization.
In-Situ Annealing of Metal Thin Films on Silicon
Authors: Chen L. J. , Mayer J. W. 
Published: June 2020

In-situ dynamical experiments in the transmission electron microscope (TEM) have long interested electron microscopists. In designing and performing the experiments, it is important to minimize the influences of the factors, which include the specimen thickness, electron beam heating, electron irradiation and specimen environments that may affect the validity of in-situ experiments. Comparisons of the results with those of other experiments are also very desirable.In microelectronic device fabrication process, it has become increasingly common to react a few hundred Å in thickness metal films with silicon substrate to form silicide contacts. Ni thin films on silicon have been chosen for in-situ annealing study since this system has been extensively investigated by Rutherford backscattering and glancing angle x-ray experiments. In-situ annealing of Co, Mo, Ti, Pd and W thin films on silicon have also been performed.Ni films, 300 and 400 Å thick, were electron gun deposited on (001) n-type silicon. Thin foils for TEM examination were chemically polished from silicon side. A JEOL 100B microscope equipped with a side entry, single tilt hot stage was used for TEM study.
∣ḡ • b∣ = 0 Images of Small Precipates
Authors: Sykes L. J. , Hren J. J. 
Published: June 2020

The authors have previously reported that small platelike precipitates formed during neutron irradiation of an Al-Cu alloy (A1 + 100 ppma Cu, irradiated to a fluence resulting in 0.26 dpa) produced ∣g•b∣ = 0 images similar to small dislocation loops. The precipitate images, however, contain detail indicating structures more complex than a simple dislocation loop. These observations were made as a continuation of the work of Farrell and Houston, who surveyed the radiation damage behavior of a large number of aluminum alloys. Our most recent work, using a refined model, suggests that much additional information can be derived about the nature of the precipitate from dynamical two-beam images.Computer simulation of images was used to test models for the strain around the precipitates. EDS measurements, electron diffraction and SAXS failed to give useful clues as to the nature of the precipitates and so our model had to be based on a postulated relationship between the two-beam image and the strain field of small defects. Our results indicate that the defect in Figure 1 is a disc-shaped precipitate whose thickness is less than, and whose radius is greater than, the matrix material it replaces.
Interfacing of a TEM/STEM System to a Computer
Authors: Hagemann P. 
Published: June 2020

The use of computers in the analytical electron microscopy today shows three different trends (1) automated image analysis with dedicated computer systems, (2) instrument control by microprocessors and (3) data acquisition and processing e.g. X-ray or EEL Spectroscopy.While image analysis in the T.E.M. usually needs a television chain to get a sequential transmission suitable as computer input, the STEM system already has this necessary facility. For the EM400T-STEM system therefore an interface was developed, that allows external control of the beam deflection in TEM as well as the control of the STEM probe and video signal/beam brightness on the STEM screen.The interface sends and receives analogue signals so that the transmission rate is determined by the convertors in the actual computer periphery.
Micro-Computer Control for a HB501 STEM
Authors: Joy David C. 
Published: June 2020

Micro-computers conveniently provide the basis of a powerful data collection, display and storage system for an electron microscope. In the example described here a Vacuum Generators HB501 STEM has been interfaced with an APPLE II micro-computer. The APPLE, with 48k of available core memory and a single mini-diskette system of 256k. byte capacity, was fitted with 16 input channels of analog-to-digital conversion (Interactive Structures AI-Ø2) and 8 output channels of digital-to-analog conversion (Interactive Structures AO-Ø3).Figure (1) shows a block diagram of the system and its interconnections to the microscope. ADC channels Ø to 5 monitor the excitations of the six lenses (two condenser, one objective and three post specimen) of the HB501. These inputs are taken directly from the feedback shunt resistors in the lens power supply and fall directly in the range 0 to +5 volts required for the ADC. Channels 6 to 9 measure the X,Y coordinates and X,Y tilt-coordinates of the specimen stage, by monitoring the voltages derived from the position-sensing potentiometers on the stepping drive motors. These signals in the range ±0.5V are converted to the required 0 to + 5V level by operational amplifiers.