bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhomogeneities in hot-pressed silicon nitride
Authors: Donlon W.T. , Shinozaki S. , Mindroiu V. , Beckwith E.C. , Ezis A. 
Published: June 2020

Silicon nitride is currently being applied in wear applications such as cutting tools (1-2) and is being actively investigated for use as structural components in ceramic heat engines (3). Processing flaws and metallic inclusions such as Fe,Al, and free silicon are known to influence the physical and mechanical properties of the final product.In this investigation, flaws in a hot-pressed silicon nitride containing Y2O3 were identified using optical, scanning electron, (SEM) and transmission electron microscopy (TEM).A representative microstructure of the silicon nitride which was investigated is shown in Fig. 1. The size of typical β-Si3N4 grains is less than one micron, and the intergranular phase (which is rich in yttrium) is completely crystalline and appears dark in this bright-field micrograph.
Analytical electron microscopy of SiC implanted with Cr ions
Authors: Sklad P. S. , Angelini P. , McHargue C. J. , Williams J. M. 
Published: June 2020

Silicon carbide is an attractive structural material for high temperature applications that require chemical stability in aggressive environments and wear resistance. In order to investigate ion implantation as a means of improving surface properties, specimens of SiC were implanted with chromium ions. The present work is concerned with characterizing the near-surface microstructure produced by implantation and monitoring changes which occur during post-implantation annealing.A polycrystalline specimen of α SiC, pressureless sintered with boron additions by the Carburundum Co., was implanted with chromium ions at ambient temperatures. In order to obtain a broad fairly uniform depth distribution a multiple-energy implant schedule was employed: 4.03 x 1015 Cr ions/cm2 were implanted at 95 keV, 7.26 x 1015 Cr ions/cm2 were implanted at 190 kev, and 10 x 1015 Cr ions/cm2 were implanted at 280 keV.
Intergrowths and aggregates of natural kaolinite
Authors: Hurst V. J. , Rigsby W. E. 
Published: June 2020

Kaolinite crystallites, which are pseudohexagonal platelets, generally are found not singly but as intergrowths or aggregates of several platelets.Until recently only coarser intergrowths (Figs. 1-2) could be imaged with SEM in sufficient detail for intersectional relationships to be unambiguously interpreted. With newer SEMs, the smallest intercrystal relations can be resolved. Floccules can be distinguished from intergrowths. In-situ crystallization texture (Fig. 3) can be distinguished from sedimentational fabric (Fig. 4).
High-resolution image processing of bright-field electron micrographs
Authors: Kirkland E.J. , Siegel B.M. , Uyeda N. , Fujiyoshi Y. 
Published: June 2020

A general form of the analytical model of a CTEM bright field image is:(1)where G is the Fourier Transform (F.T.) of the recorded image intensity, F is the F.T. of the complex specimen transmission function, CO is a background constant, δ is the Dirac delta function, N is a random noise component, is a spatial frequency vector in the image plane, and Tμ is the transmission cross coefficient. In the special case of coherent imaging:(2)(3)
Three-dimensional displays of computer-generated and real images
Authors: Sher Lawrence D. 
Published: June 2020

This paper discusses a new generic kind of computer-generated display, one which can realistically be described as having depth rather than depth cues. It was developed to its present state by this author and has been called SpaceGraph, a name which will be used here.Computer output is normally on paper or on a CRT, both of which are nominally flat. The SpaceGraph display provides computer output which is not flat. Its output is displayed in a volume. The output can take two basic forms: a computer-generated figure, like a stick figure of a molecule, or image data acquired from a volume sensing system, e.g., as encountered in reconstruction from projections or from serial sections. Since the display volume's spatial z-axis is just as real and as versatile as its x- or y-axes, the user has a wholly new display resource.
Calculated images of dolomite - calcite interfaces: Feature identification in saddle dolomite
Authors: King A.H. , Chen Fu-Rong , Reeder R.J. , Barber D.J. 
Published: June 2020

Images of saddle dolomite show defects which appear as fringe contrast effects as seen in Fig.1. These defects appear to branch or terminate, frequently without any sign of a dislocation, indicating that the nature of the defects is not that of a stacking fault, at least in the usual sense of that term. The possibility that the faults are merely thin layers of compositional variants of the parent phase has accordingly been investigated.The mineral phases dolomite, CaMg(CO3)2 and calcite, CaCO3, have very similar structure, both having rhombohedral unit cells with very similar lattice parameters: calcite may be obtained from dolomite by substituting calcium on the sites normally occupied by the magnesium ions. The problem of computing the bright field and dark field intensities for a fault arranged as in Fig.2 is particularly amenable to a scattering matrix approach, and we have carried out two-beam calculations to compare the main features of the images with those of the calculated intensity profiles.
1250-kilovolt scanning transmission electron microscope
Authors: Imura T. , Maruse S. , Mihama K. , Iseki M. , Hibino M. , Saka H. , Kubozoe M. , Matsui I. , Satoh H. , Katagiri S. 
Published: June 2020

Ultra high voltage STEM has many inherent technical advantages over CTEM. These advantages include better signal detectability and signal processing capability. It is hoped that it will explore some new applications which were previously not possible. Conventional STEM (including CTEM with STEM attachment), however, has been unable to provide these inherent advantages due to insufficient performance and engineering problems. Recently we have developed a new 1250 kV STEM and completed installation at Nagoya University in Japan. It has been designed to break through conventional engineering limitations and bring about theoretical advantage in practical applications.In the design of this instrument, we exercised maximum care in providing a stable electron probe. A high voltage generator and an accelerator are housed in two separate pressure vessels and they are connected with a high voltage resistor cable.(Fig. 1) This design minimized induction generated from the high voltage generator, which is a high frequency Cockcroft-Walton type, being transmitted to the electron probe.
Some data of a superconducting lens with iron circuit
Authors: Lefranc G. , Anzinger H. , Knapek E. , Dietrich I. 
Published: June 2020

In our laboratory the electron optical data of several iron free lens types were calculated from their axial field distribution /1/. One of these lens types, the shielding lens, which was especially suitable for our purposes has been constructed for practical application and it is now in operation in several electron microscopes. A point to point resolution of 0.15 nm could be established and the specimen drift could be reduced in comparison with conventional microscopes to 0.03 nm/min. The shielding lens is particularly of advantage for high voltage microscopes. But the performance is also satisfactory in the 100 kV range.The shielding material, however, we use for our shielding lens is not commercially available and the machining of this material is difficult. For this reason we wanted to find out if in principle a superconducting iron circuit lens could replace the shielding lens in our system (Fig. 1) at lower beam voltages, i.e. if an iron circuit lens with the same dimensions and the same electron optical data could be constructed.
On-line computer archival storage of thin specimen images by means of STEM
Authors: Okagaki T. , Jones M. , Clark B.A. , Pan T. , Hsing R. , Tzou H.H. 
Published: June 2020

The computer archiving of diagnostic electron photomicrographs of thin sections has inherent merits: (1) a large amount of dark room processes can be eliminated, (2) an image file in the archive can be easily accessed and displayed, (3) the archive can be incorporated into a hospital or laboratory based computer information data bank, (4) an image can be easily enhanced and its contrast and grey level can be adjusted to the optimum for interpretation, (5) grey scale linearity can be preserved for future densitometry, (6) morphometry and pattern recognition can be applied, and (7) a distribution map of data from analytical electron microscopy can also be incorporated.Although a photographic film can store an extremely large amount of information, recent development of large storage devices, notably optical (laser) disks, make archiving of a high resolution digitized image physically and economically feasible.
High-resolution structural analysis of eukaryotic ribosomal RNAs by scanning transmission electron microscopy
Authors: Oostergetel G.T. , Hainfeld J.F. , Wall J.S. , Boublik M. 
Published: June 2020

The structure and function of ribosomes, small cellular organelles involved in protein synthesis, are determined by both their macromolecular components - proteins and RNAs. The protein/RNA ratio depends on the evolutionary level of the organism. In eukaryotic ribosomes the protein/RNA ratio is ~ 1:1 (w/w). While the number and composition of ribosomal proteins varies from species to species, the number and composition of RNAs is highly conserved.We have chosen the 18S and 28S ribosomal RNA isolated from baby hamster kidney cells to study the structural role of eukaryotic RNAs on the ribosome. Similarity in the extent of secondary structure suggests that the eukaryotic RNAs have similar “domain” structure as their prokaryotic counterparts. This structure consists of segments of double stranded stems, single strands and loops. However, folding of these segments into a conformation contributing to the 3-D structure of the ribosome remains to be established.
Initiation of placentation in the pig
Authors: Keys J.L. 
Published: June 2020

The microscopic structure of the mature placenta in domesticated species has been described in many publications but the early developmental stages have only been studied in detail within the past decade. The earliest date previously cited for initial attachment of the porcine trophoblast to the maternal epithelium is 14 to 18 days of gestation. This investigation was undertaken to establish morphological changes in the maternal epithelium in preparation for this event.Four or 5 nulliparous gilts were slaughtered on each of d10 and d13 of the estrous cycle and pregnancy (d0=1st d of estrus), and tissue samples prepared for correlative light and electron microscopy. Samples were compared between gilts on equivalent days of the cycle/pregnancy in order to determine endometrial changes specific to pregnancy. Sites adjacent to embryos were contrasted with those lacking trophoblastic contact within the same animal to investigate whether epithelial adaptations for attachment are localized to trophoblast proximity or represent a generalized uterine response.
Ultrastructure of Melosira resting cell rejuvenation
Authors: Bourne C. E. M. , Sicko-Goad L. 
Published: June 2020

Much recent attention has been focused on vegetative survival forms of planktonic diatoms and other algae. There are several reports of extended vegetative survival of the freshwater diatom Melosira in lake sediments. In contrast to those diatoms which form a morphologically distinct resistant spore, Melosira is known to produce physiological resting cells that are indistinguishable in outward morphology from actively growing cells.We used both light and electron microscopy to document and elucidate the sequence of cytological changes during the transition from resting cells to actively growing cells in a population of Melosira granulata from Douglas Lake, Michigan sediments collected in mid-July of 1983.
Tensile Failure of 55-Nitinol Wire
Authors: Grace F. I. 
Published: June 2020

An interest in NiTi alloys with near stoichiometric composition (55 NiTi) has intensified since they were found to exhibit a unique mechanical shape memory effect at the Naval Ordnance Laboratory some twelve years ago (thus refered to as NITINOL alloys). Since then, the microstructural mechanisms associated with the shape memory effect have been investigated and several interesting engineering applications have appeared.The shape memory effect implies that the alloy deformed from an initial shape will spontaneously return to that initial state upon heating. This behavior is reported to be related to a diffusionless shear transformation which takes place between similar but slightly different CsCl type structures.
Scanning Electron Microscopy of Single-Crystal NiO Energetics
Authors: Murr L. E. , Miglionico C.J. 
Published: June 2020

The fusion of NiO powder in an oxygen-rich oxy-hydrogen flame at ∼2000°C at atmospheric pressure has been observed to produce, in addition to single-crystal Ni growth, a residual (001) vicinal NiO growth which exhibits an intergrowth and regrowth of isolated particles characterized as equilibrium (regular-faced) polyhedra, and a prominent “negative crystal” phenomena in the vicinal faces of the oxide. Observations of the NiO crystal growth and particle morphologies were made in a JE0L-JSM-50A scanning electron microscope operated at 25 kV in the secondary electron emission mode. The samples were uncoated.Figure 1(a) shows typically the NiO growth phenomena observed, while Fig. 1(b) illustrates the vicinal-surface growth features schematically. The major structural features can be characterized as terraces, ledges, and kinks, with "negative" growth features related to systematic terrace-atom desorption.
Application of Energy Dispersive X-Ray Analysis to Textile Fibers
Authors: Goynes W. R. , Carra J. H. 
Published: June 2020

In development of chemically finished textile products it is advantageous to be able to determine locations of interactions of finish and fiber. Microscopical tests have been developed for this purpose but those showing internal fiber interactions have been largely subjective. Energy dispersive X-ray (EDX) analysis has extended the capability for location of deposited or reacted elemental species from fabric finishes.Effectiveness and durability of flame-retardant finishes for textile fabrics depend in part on location and distribution of flame-retardant chemicals. Location of the finish within yarn and fiber structures aids in production of the most efficient flame-retardant product and may serve as well for quality control of flame-retardant processes.
On the Feasibility of Quantitative Microchemical Analysis of Thin Metal Foils
Authors: Fraser G. L. , Zaluzec N. J. , Woodhouse J. B. , Sis L. B. 
Published: June 2020

Several techniques have been developed for the quantitative microchemical analysis of thin foils. These procedures require that in an alloy AB the measured intensity ratio, IA/IB frora the foil be independent of foil thickness. Cliff and Lorimer find that this condition is met in all cases they have examined whereas Jacobs and Baborovska show data where absorption of longer wavelength X-rays was apparent.The present study was undertaken to evaluate these procedures for the combination of a scanning transmission electron microscope (JEOL JSEM 200) and an energy dispersive analyzer (Ortec).
Inner Shell Ionization by 60 keV Electrons, Application to Microanalysis
Authors: Kihn Y. , Sevely J. , Jouffrey B. 
Published: June 2020

By using a Castaing-Henry filtering device adapted on a Siemens Elmiskop I electron microscope, we have directly observed plasmon and inner shell excitations by 60 keV electrons on electron energy loss spectra. Inner shell excitation edges have been detected up to 1900 eV.By comparing L and K inner shell excitation profiles in the case of Magnesium, Aluminium and Silicon, it is concluded that the optical selection rules, △1 = ±1, explain the shape of the spectrum after the edge in a first approximation.
An Improved Specimen Mount for Scanning Electron Microscopy
Authors: Lamvik M. K. , Lin S. D. 
Published: June 2020

The development of a specimen holder for use without adhesives was originally motivated by the need to maintain an especially clean specimen environment in ion-pumped high vacuum scanning microscopes. Since then, it has become clear that the system is very convenient and inexpensive in everyday use and would be of value in many types of scanning microscopes. We report here some recent improvements in the system.The design is based on the use of a simple disc as the specimen mount, rather than a more complex shape such as a "stub." Since the disc may be the actual substrate upon which a specimen is obtained, no adhesive is needed to attach the substrate to a mounting stub.
The Double-Field Condenser Objective Lens
Authors: Anderson K. , Brookes K. A. , Fibow D. C. 
Published: June 2020

The illumination system of the conventional transmission electron microscope is designed to provide an adequate level of coherent illumination over the field of view being examined. The additional requirement of providing the maximum possible current into very small (sub-micron) focussed spots, as is required by X-ray microanalysis for example, necessitates a probe forming lens with a very short working distance and has previously been met by using either a mini-lens or the prefield of the objective lens when used in the Single-Field Condenser-Objective mode.The SFCO gives the smallest spot size and aberration parameters but suffers from the disadvantage that the illumination and imaging fields are not independently controllable.
Determination of Energy Spread and Source Size by Optical Diffraction
Authors: Frank J. 
Published: June 2020

Since the effect of energy spread and angular spread of illumination on the contrast transfer function is known from theoretical investigations, these experimental parameters can in turn be obtained by careful analysis of electron micrographs. For Gaussian energy spread (halfwidth △E), negligible voltage and current fluctuations and a Gaussian source distribution (half-width α), the coherent transfer function for monochromatic electrons appears multiplied with the envelope function(θ scattering angle, λ electron wavelength, E0energy, △z defocus; Cc, Cschromatic and spherical aberration constants). This causes an attenuation of the image Fourier transform at high spatial frequencies and is responsible for the fact that the visible bandlimit in optical diffraction patterns is well below the aperture limit.
Cellular Precipitation of Gamma Prime in Iron-Nickel Based Alloys
Authors: Gelles D. S. 
Published: June 2020

A coherent precipitate known as gamma prime develops in iron-nickel base alloys when alloying additions of aluminum and titanium are included. The gamma prime phase is an ordered fcc structure of Ll2 symmetry having an Ni3(A1, Ti) composition. Gamma prime is generally found as a fine spherical or cubic precipitate, uniformly distributed throughout the material. Imaging is usually difficult because lattice mismatches are small and only superlattice reflections of weak intensity are available for dark field imaging. This paper presents evidence that the gamma prime phase can be formed by discontinuous precipitation, developing a typical cellular structure.An experimental alloy, Fe-14.9Cr-34.8Ni-l.5Al-l.98Ti-.004C (weight percent), has been given a solutionizing treatment of 1145°C for 1 hour followed by an air quench and an aging treatment of 815°C for 1 hour. Examination of the microstructure by TEM indicated that a cellular precipitate had developed extensively at grain boundaries.
Direct Observation of Radiation Induced Precipitation in High Voltage Electron Microscope
Authors: Wu Wei-Kuo , Washburn Jack 
Published: June 2020

Long needle-shaped radiation induced precipitates oriented along <110> directions were first reported by Nes and Washburn from observation using hot stage high voltage electron microscopy. Similar long rod-like defects have also been observed in boron ion implanted silicon.Our recent results show that most long rod-like defects formed during postimplantation annealing of boron ion implanted silicon are boron precipitates. The cause for the formation of these long rod-like defects is assumed to be replacement of substitutional boron by silicon selfinterstitials.To substantiate this mechanism two samples were irradiated in the high voltage electron microscope. Sample A was a boron doped <111> oriented silicon of resistivity 0.75 Ω-cm (2.5x10l6 B/cm3) and sample B was phosphorous doped, of resistivity 2 Ω-cm (2.7x10l5 p/cm3).Figure 1 shows the sequential development of long rod-like defects in sample A held at 620°C during irradiation with 650 keV electrons.
Electron Microscopy of U-6.3 wt% Nb Alloy
Authors: Ehlinger A. O. , Staudhammer K. P. , Mille A. R. 
Published: June 2020

Addition of small amounts of niobium to uranium generally produces an alloy that has an increase in strength and greater corrosion and oxidation resistance. While many investigators have studied the physical metallurgy and mechanical properties of dilute uranium alloys, to date there have been no studies utilizing transmission electron microscopy to study the precipitation behavior of the U-6.3% Nb alloy.The present investigation was undertaken in order to determine by TEM the mode of precipitation of the U-6.3% Nb alloy when aged at various times and temperatures. Samples in the form of charpy bars, were treated at 850°C for 30 min., and water quenched (γ - quenched). These samples were then aged for 180 min. at 250°C, 385 min. at 254°C, and 72 min. at 358°C, to give 100, 117, and 160 KSI-yield strength respectively. The resulting microstructures were examined in a Hitachi-Perkin Elmer H.U. 200 F electron microscope operated at 200 KV; employing a goniometer tilt stage.
Identification of Asbestos Fibres in a Water Sample by X-Ray Microanalysis
Authors: Brookes K. A. , Finbow D. , Samuel Madeleine 
Published: June 2020

Investigation of the particulate matter contained in the water sample, revealed the presence of a number of different types and certain of these were selected for analysis.An A.E.I. Corinth electron microscope was modified to accept a Kevex Si (Li) detector. To allow for existing instruments to be readily modified, this was kept to a minimum. An additional port is machined in the specimen region to accept the detector, with the liquid nitrogen cooling dewar conveniently housed in the left hand cupboard adjacent to the microscope column. Since background radiation leads to loss in the sensitivity of the instrument, great care has been taken to reduce this effect by screening and manufacturing components that are near the specimen from material of low atomic number. To change from normal transmission imaging to X-ray analysis, the special 4-position specimen rod is inserted through the normal specimen airlock.
Charging of Small Particles in the Scanning Electron Microscope
Authors: Krakow W. , Nixon W. C. 
Published: June 2020

Charging effects in the scanning electron microscope (SEM) have been investigated and various contrast mechanisms have been explained which include both the primary beam and secondary electron trajectories and take into account specimen parameters. In particular, Weitzenkamp measured potentials of cylindrical fibers which could be suspended above a replica of a ruled surface to measure charge density on these organic polymer materials.We have been able to obtain the equivalent information on the charge density from SEM micrographs of small charged particles. Fig. 1, shows a backseattered electron image of a 10μm polystyrene particle supported on a gold coated linear hologram grating having spacing of approximately 3.6μm. The grating distortion indicates a strong negative charge on the particle which deflects the 10 kV primary beam. The grating distortion is asynmetric due to a specimen tilt of 70 degrees.