bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effets of surfaces on precipitate morphology in irradiated thin foils
Authors: Potter D.I. , Taylor A. 
Published: June 2020

Thermal aging of Ni-12.8 at. % A1 and Ni-12.7 at. % Si produces spatially homogeneous dispersions of cuboidal γ'-Ni3Al or Ni3Si precipitate particles arrayed in the Ni solid solution. We have used 3.5-MeV 58Ni+ ion irradiation to examine the effect of irradiation during precipitation on precipitate morphology and distribution. The nearness of free surfaces produced unusual morphologies in foils thinned prior to irradiation. These thin-foil effects will be important during in-situ investigations of precipitation in the HVEM. The thin foil results can be interpreted in terms of observations from bulk irradiations which are described first.Figure 1a is a dark field image of the γ' precipitate 5000 Å beneath the surface(∿1200 Å short of peak damage) of the Ni-Al alloy irradiated in bulk form. The inhomogeneous spatial distribution of γ' results from the presence of voids and dislocation loops which can be seen in the bright field image of the same area, Fig. 1b.
A TEM study of discontinuous precipitation in Cu-Be alloys
Authors: Michael Joseph R. 
Published: June 2020

It is known that a lamellar discontinuous precipitate forms in aged Cu-1.8wt.% Be alloys. The purpose of this study was to investigate factors which influence the formation of the precipitate and to characterize its growth.To determine the effect of solution treatment on the discontinuous precipitate, specimens were solution treated at 800°C, 850°C, and 900°C for 1 hour followed by an ice water quench. Some of the solution treated specimens were examined in the as-quenched condition. The remaining specimens were aged at 340°C for 24 hours. The specimens were thinned with a twin-jet electropolishing unit using 30% HNO3 in methanol at -60°C. The specimens were then examined using either an RCA-EMU3G or a Philips EM-300 electron microscope.Each solution treated specimen was not single phase, but showed some residual grain boundary precipitate which implies that the solution anneal was not sufficient, or else precipitation had occurred during quenching. The higher solution treatment temperatures slightly reduced the amount of this grain boundary precipitate, but none completely removed it, even after five hours at temperature,indicating quench decomposition as the mechanism responsible.
A comparative electron microscopic histochemical study of myxoid liposarcoma and myxoid variant of malignant fibrous histiocytoma
Authors: Lam Ronald , Hawkins Earl , Maeda Koichi 
Published: June 2020

Despite several ultrastructural studies of myxoid liposarcoma and myxoid variant of malignant fibrous histiocytoma, the histochemical nature of the extracellular matrix has not been fully explored. The purpose of this study is to cytochemically localize the glycosaminoglycans (GAG)and to compare these two apparently histogenetically different neoplasms which share a common feature of testicular hyaluronidase sensitive myxoid stroma.Two sarcomas typical of myxoid liposarcoma and myxoid fibrous histiocytoma were examined by electron microscopy after fixation in 2.5% glutaraldehyde, 0.2% ruthenium redglutaraldehyde, and pre-embedment staining with colloidal iron (CI). Intracellular GAG could be localized in both tumors by CI. The stellate lipid-containing mesenchymal cells of the myxoid liposarcoma exhibited CI reactive sites characterized by multiple electron dense particles in secondary lysozomes as well as in small dense bodies (93-273 nm) which probably represent secretory granules (Fig. 1A).
Square-array fiber cell membranes in the mammalian lens
Authors: Costello M.J. , McIntosh T.J. , Robertson J.D. 
Published: June 2020

Two types of intercellular contacts have been observed between lens fiber cells. Gap junctions showing the normal EF-pit/PF-particle fracture pattern have been Identified in a number of species and predominate in the chick where they can cover as much as 50% of the cell surfaces. A second type of junction appears in mammalian lenses and is composed of membranes containing square crystalline arrays. In an effort to further characterize the square array membranes we have compared fragments of intact lenses to isolated junctions and used a variety of freeze-fractureetch procedures to visualize the unusual fracture morphology.Fig. 1A shows a typical fracture pattern of fiber cell membranes in a fragment of intact rat lens cortex. Two fracture surfaces are observed separated by a large step (arrows). The upper surface is covered by large irregularly shaped particles. In the lower membrane surface 8-9 nm dia. particles are clustered in some regions into small square arrays; a few tightly packed clusters appear to be covered by a small plaque of amorphous material (circles).
An association between microtubules and nucleocapsids in nucleopolyhedrosis virus-infected hemocytes and fat body in the gypsy moth
Authors: Shields K. S. 
Published: June 2020

Studies of nucleopolyhedrosis virus infection in midgut cells of corn earworm and cabbage looper larvae indicate that cytoplasmic microtubules might be involved in the vectorial movement of nucleocapsids from the microvilli, where invasion takes place, to the cell nucleus, where replication occurs. Such an association between cytoplasmic microtubules and adenovirus has been shown in Hela cells. During a recent study of the pathway of nucleopolyhedrosis virus infection in the gypsy moth, an unusual relationship was observed between microtubules and nucleocapsids in infected hemocytes and fat body cells.Fourth instar gypsy moths were fed a lethal dose of nucleopolyhedrosis virus. Larvae died of virus in 11 to 12 days. At intervals beginning at 12 hours and continuing to 10 days post-ingestion of virus, hemolymph was collected and fat body was dissected from groups of larvae.
The stability of calcium oxalate during electron irradiation in an AEM
Authors: Newkirk J.W. , Khan S.R. 
Published: June 2020

Calcium Oxalate is a major constituent of most kidney stone material. Electron microscope studies of materials containing calcium oxalate are complicated by decomposition during observation. This structural instability not only limits the observation time but also precludes the use of focussed probe techniques such as microdiffraction.Two factors under the control of the experimenter which could help increase observation time are accelerating voltage and specimen temperature Available at the Center is a JEOL 200CX TEM capable of 200kV equipped with a Gatan 636 cold stage which can cool a specimen to -180C in-situ. Calcium Oxalate was deposited on carbon support films from an aqueous solution. The resulting specimens were then examined at 200kV at OC, -50C, -100C, -180C, and room temperature (RT) and at 100kV at 0 and -100C. Selected area diffraction patterns were taken at specific time intervals in order to follow the decomposition. This was done at least three times at each condition in order to insure reproducibility. Care was taken that the beam current (~ 20 microamps) and illumination were the same at 100 and 200kV.
Vitelline and chorionic membranes of an ichneumonid parasitoid
Authors: Norton W.N. , Vinson S.B. 
Published: June 2020

The chorionic membrane of parasitoid eggs is of particular interest to individuals investigating parasite-host interactions at the cellular level. Results of several studies indicate that the chorionic surface and/or material associated with the latter are of importance in providing protection against the host immune system. The primary objective of the present study was to determine, ultrastructurally the manner in which the vitelline and chorionic membranes of an ichneumonid parasitoid,Campoletis sonorensisare synthesized.The reproductive system ofC. sonorensisconsists of 2 ovaries, each composed of 12 ovarioles. Within the ovarioles developing oocytes are enclosed by a single layer of follicular tissue. Adjacent follicle cells adhere by means of septate desmosomes and gap junctions (Fig.1). During the initial stages of vitellogenesis or yolk deposition each follicle cell is abundantly supplied with non-membrane bound ribosomes, but rough endoplasmic reticulum is sparse.
Scanning electron microscopy of flowering apices
Authors: Lee Kit W. 
Published: June 2020

Critical point drying (CPD) is widely used for the preparation of delicate shoot apices for scanning electron microscopy (SEM). In order to prevent charge accumulation on the dehydrated specimen, it is necessary to coat the surface with metal by vacuum evaporation or sputtering. However, cellular shrinkage is the most common irritating artifact for the shoot apices thus prepared (1). In addition, specimen charging is a common occurrence during SEM observation.Direct examination of mature plant materials (e.g., leaf, stigma, pollen, etc.) in the SEM is one of the alternative preparation methods (2,3). Nevertheless, such a simple technique has not been commonly used for floral apices. The aim of the present investigation was to explore the feasibility of using unfixed, uncoated apices for SEM.
Roller technique for TEM preparation of viscous fluids and particle suspensions
Authors: Burnett P. , Chiuve M. , McCann M. , Walworth V. 
Published: June 2020

We have developed a rapid technique that utilizes pressure rollers to spread suspensions of particles, viscous dispersions or polymer latices onto electron microscope grids.We use motor-driven rubber rollers, as pictured in the schematic drawings of Figure 1. Other pressure roller systems, both motor-driven and hand-operated, have also worked satisfactorily. The grid and a drop of the fluid are placed between two .004” polyester sheets. Passing this sandwich through the rollers spreads a thin layer of the solution or dispersion onto the grid. The pressure is adjusted to control the thickness of the coated layer. The grid is removed and examined in the microscope.
STEM investigation of the low temperature ashing of coal
Authors: Allen Robert M. , VanderSande John B. 
Published: June 2020

Low temperature ashing (LTA) with an oxygen plasma is done in coal research to burn off the organic material in a powdered coal sample in order to concentrate minerals in the coal for subsequent analysis. The assumption is made that the final ash represents the mineral matter because no significant mineral transformations occur at LTA temperatures (∼150C). The present work was performed to examine the changes which do take place during the LTA of coal.The coals used in this work were PSOC 98, an HVC-bituminous coal from Wyoming, and PSOC 279, an HVB-bituminous coal from Indiana. The raw coal samples were ground to -200 mesh and a portion of each was characterized by a STEM and an electron microprobe. Sample preparation has been described elsewhere. The STEM used was a JEOL 200CX; the microprobe was a JEOL 733 equipped with digital beam control, and a commercially-available software package for the automated analysis of mineral particles in coal samples.
Subgrain rotation during in-situ annealing of Al-6 wt% Ni in the HVEM
Authors: Chan H. M. , Humphreys F. J. 
Published: June 2020

Recently a series of commercial aluminum alloys has been developed (based on eutectic compositions), which contain a high volume fraction (∼10%) of second phase [1,2]. This paper describes the behavior of one such alloy, when thinfoil specimens (75% defd.) were annealed in-situ in the HVEM.The eutectic alloy studied was Al-6 wt% Ni. The alloy heat treatment and particle (Al3Ni) dispersion parameters are given in Table 1. Three-mm discs were punched from as-deformed material. Thin foil specimens were prepared by standard jet polishing techniques. In-situ annealing was carried out in the AEI EM7 high voltage electron microscope at 500 kV, using a platinum ribbon heating stage [3].
Metastable and stable structures occurring during crystallization of some Cu-Ti amorphous alloys
Authors: Marshall A. F. , Lee Y. S. 
Published: June 2020

Amorphous Cu-Ti alloys belong to the inter-transition metal class of metallic glasses which, in contrast to the metal-metalloid glasses, can often be made amorphous over a wide range of compositions. Crystallization studies of these alloys not only provide information on glass stability, but also allow characterization of equilibrium and metastable crystal phases and microstructures across a broad portion of the phase diagram.Above 40 at% Ti, the Cu-Ti system shows a series of tetragonal intermetallics based on a body-centered tetragonal subcell and showing one-dimensional ordering of Cu and Ti along the c-axis (Fig. 1). Crystallization in the composition range about 40 at% Ti has been shown to involve intermediate transformation to a metastable microcrystalline (bcc) structure; lattice images of the fully crystallized material show a mixture of the Cu3Ti2 and Cu4Ti3 phases.
Yorktown display architecture
Authors: Gupta Satish 
Published: June 2020

The advances in VLSI and CRT technology over the past ten years have resulted in feasible implementations of raster-scan displays capable of displaying complex images with reasonably high resolutions. Single chips capable of storing 64 Kilobits can be used to build memory systems capable of storing such high resolution images. The ability to manipulate these high resolution images interactively requires the ability to change a large amount of information rather rapidly.At the IBM Thomas J. Watson Research Center, we have built a display system which addresses the problem of changing high resolution display images rapidly. The system was design to allow the rapid manipulating of images in wide range of applications. The applications planned include text formatting, computer aided design, and image processing applications which process digitized images.
Energy band effects in Si L ELS edges of Si and SiC
Authors: Skiff W.M. , Carpenter R.W. , Lin S.H. 
Published: June 2020

Interpretation of near-edge core shell fine structure in electron energy loss spectra (ELS) can aid in the phase identification of small areas of sample in an analytical transmission electron microscope. Previously we performed extended Hückel molecular orbital (EHMO) calculations on a series of tetrahedral Si clusters. The resulting energies and wavefunctions were used to calculate 1st Born inelastic scattering cross sections for discrete transitions to molecular states. We have extended this work to include the effects of translational symmetry in crystalline materials - energy band effects.Si and α-SiC samples were prepared by crushing, chemical dissolution, or grinding followed by ion beam thinning. A cryogenic stage (80K) was used to eliminate specimen contamination. ELS spectra were acquired with a 100keV converged electron probe (100Å diameter at specimen, 13mrad convergence angle) from single scattering regions (<500Å thick). Samples were tilted into kinematic diffracting conditions, with the Si near the [111] and SiC near the [0001] zone axes.
Cavity nucleation on special boundaries
Authors: Romeu L. D. , Reyes J. 
Published: June 2020

All present theories of cavity formation assume cavities are nucleated during creep on geometrical irregularities at grain boundaries and triple junctions. The resulting (required) tensile stress concentration enhances diffusional creep in the vicinity of the boundary producing a high vacancy flux which ends up nucleating a cavity. No mention is done of the role played by the structure of the boundary. In this paper we present experimental evidence indicating that cavity nucleation is dependent on the structure of the boundary and that cavities in pure metals are nucleated at special boundaries.According to Bollman, a lattice dislocation impinging on a boundary can dissociate into grain boundary dislocations with non crystalline Burgers vectors (GBDs). Also, Pond has shown that further dissociation into partials can occur in certain boundaries. When the degree of good fit decreases, the Burgers vector of any possible GBDs decrease and dislocations tend to be largely spread out becoming “dissolved” into the boundary. Boundaries capable of sustaining dislocations with relatively large Burgers vectors (long range strain fields) are called special boundaries.
Microstructure of trona sorbents from fossil fuel plant full-scale dry injection tests
Authors: Greer R. T. , Zhang D. T. 
Published: June 2020

The use of dry sorbents for the removal of SO2 from the flue gas of coal-fired power plants is of interest in reducing the complexity of SO2 removal and appears to offer economic incentives. In 1982, the Electric Power Research Institute, Public Service company of Colorado (PSCCO), and Multi-Mineral Corporation co-sponsored a full-scale demonstration of the dry injection process at the Cameo Station, Unit 1, of PSCCO near Grand Junction, Colorado.Laboratory comparative studies of nahcolite (NaHCO3), trona and soda ash Na2CO3) with that exposed to gas streams of air or of SO2 at elevated temperatures have been reported to provide microstructural data (from SEM) for correlation with microchemical information and phase identification for possible reactions of these materials which may occur under conditions for injection of a dry sorbent at the utility plant, and which may bear on the effectiveness of SO2 reaction with sorbents.
Endocytosis and the lysosomal apparatus of rat Leydig cells
Authors: Lalli M.F. , Hermo L. , Clermont Y. 
Published: June 2020

The Leydig cells of the rat testis which are involved in testosterone production contain an abundance of smooth endoplasmic reticulum and mitochondria (Figs. 2,6). These cells also possess many peroxisomes, lysosomes and multivesicular bodies (MVB's). On the cell surface, the plasma membrane contains numerous short microvilli, small invaginations and large plasmalemmal folds which appear to engulf extracellular fluid. There are also many large dilated vacuoles adjacent to the cell surface. The purpose of the present study is to determine if these cells show endocytic activity and to differentiate by various cytochemical means lysosomal elements from peroxisomes.To identify lysosomes, tissue chopper sections of 2% glutaraldehyde-fixed testes (containing 2.5% dextran) were incubated in media containing thiamine monophosphate as a substrate (Lalli, 1983) to demonstrate the presence of acid phosphatase or in media containing P-nitrocatechol sulfate for the demonstration of arylsulfatase (Hopsu-Havu et al., 1967).
Development of iron granules in honey bee oenocytes
Authors: Kuterbach Deborah A. 
Published: June 2020

Foraging honey bees are believed to use the earth's magnetic field, among other cues, in order to home. It has been reported that the abdomen of the honey bee contains magnetite and iron particles have been localized within abdominal oenocytes. Light microscopic investigations reveal that morphologically detectable iron granules are present only in adult animals older than six days after eclosion (emergence from the comb). This is a report of an ultrastructural examination of the oenocytes during the development of the worker honey bee (Apis mellifera) with particular emphasis on the time of appearance, number, and size of iron granules within the cells.Specimens of the different developmental stages were removed from brood comb, fixed in 2.5% glutaraldehyde in 5mM sodium cacodylate buffer pH 7.3, washed, and post-fixed with 1% osmium tetroxide. In order to preserve the lipid-rich material, rapid dehydration was accomplished by three changes of 50% acetone and two changes of 100% acetone before embedding in Polybed 812 epoxy resin.
Deformation Mechanisms of Aluminum at High Temperatures: in situ Straining Experiments in H.V.E.M.
Authors: Caillard D. , Muchin P. , Martin J. L. 
Published: June 2020

Aluminium single crystals have been deformed on a straining holder between room temperature and 550° C in a H.V.E.M. Observations are recorded on still photographs or movies.Evidence is shown of crosslip and dislocation climb.1) The formation of dislocation subboundaries has been observed at high temperature and low stresses. The increase with time of dislocation density of each boundary is explained and the coalescence of low angle subboundaries into high angle ones, is described on the basis of our observations by a model involving dislocation climb, different from the one proposed formerly by Dunn and Hibbard.
Electron Energy Analysis of Germanium and Silica Layers on Silicon Substrates
Authors: Ditchfield R. W. , Cullis A. G. 
Published: June 2020

An energy analyzing transmission electron microscope of the Möllenstedt type was used to measure the electron energy loss spectra given by various layer structures to a spatial resolution of 100Å. The technique is an important, method of microanalysis and has been used to identify secondary phases in alloys and impurity particles incorporated into epitaxial Si films.Layers Formed by the Epitaxial Growth of Ge on Si Substrates Following studies of the epitaxial growth of Ge on (111) Si substrates by vacuum evaporation, it was important to investigate the possible mixing of these two elements in the grown layers. These layers consisted of separate growth centres which were often triangular and oriented in the same sense, as shown in Fig. 1.
Thickness Dependence in Secondary Electron Emission from Carbon
Authors: Voreades D. 
Published: June 2020

Secondary electrons are used in making topographical pictures of specimens in the scanning electron microscope. A better understanding of the secondary emission process will contribute in improving the resolution in this mode of operation.Recent experiments have indicated first that the escape depth of secondary electrons is a few atomic layers at the surface of the solid and second that the backscattered electrons are much more efficient in producing secondaries than the incoming ones. The results vary considerably. However, any model that one makes, for example similar to that of Jonker, consistent with these recent experimental results, will have the thickness as an important parameter.
Simultaneous Study of Both the Surface and Interior Structure of Biological Specimens in a Scanning Electron Microscope
Authors: Lin P. S. D. , Crewe A. V. 
Published: June 2020

In contrast to optical and transmission electron microscopes, which probe the interior, the scanning electron microscope usually only reveals the exterior structure of the specimen to the biologist. This is due both to the collection of secondary electrons as signal and to the practice of coating the specimen with various heavy, noble metals.Taking advantage of their penetrating power, one can use backscattered electrons to study the interior structure of the biological specimen in a scanning electron microscope. Here a block of specimen is first stained by means similar to those practiced in transmission electron microscopy. Then a coating of carbon is applied to supress the undesirable specimen charge-up. Although the resolution in this mode will be degraded by electron-atom scattering events, this approach promises to yield more histochemical information than studying merely the topography of the specimen.
Replication of Water Droplets
Authors: Basu Samarendra , Parsons Donald F. 
Published: June 2020

This report provides a test of the physical ability to replicate wet surfaces using a hydration chamber. By using water droplets as the test object, we have removed the uncertainties of testing the chamber technique using biological cells and tissues. The principle of operation of the hydration chamber and the physical aspects of the technique have been described in another report at this meeting. The SiO replicas are shadowed with Pt-C at 35°, stripped and then observed in a transmission electron microscope (TEM).Two approaches have been made to prove that SiO replicas are formed on liquid water droplets. In the first one, the droplets have been condensed on a hydrophobic substrate by supersaturating the chamber with water vapor (Fig. 1(a)).