bluuebunny/crossref_metadata_2025_split huggingface dataset:
ALCHEMI of L12-Ordered Ni76Al21Hf3and gamma prime particles
Authors: Bentley J. , Anderson Ian M. 
Published: June 2020

Recent improvements to the atom location by channeling-enhanced microanalysis (ALCHEMI) technique now allow reliable measurements of site distributions in ordered alloys. Early zone-axis ALCHEMI of Ll2-ordered Ni3Al-based alloys was plagued by ionization delocalization; for Ni76Al21Hf3at <001> the fraction of Hf on the Al sublattice, pHf ‘Al’, = −127%. Reanalysis by statistical ALCHEMI was no better, giving pHf ‘AT’ = −220 ± 190%, contrary to the claims that delocalization effects should be minimized. The same data set analyzed with the reformulated ALCHEMI method yields pHf ‘Al’, = 80 ± 25%.Further experiments have been performed at ∼140K in a Philips CM12 operated at 120 kV and equipped with an EDAX 9900 spectrometer and superUTW Si(Li) detector. The diffracting conditions were carefully adjusted with the beam (not specimen) tilt, a probe size of ∼200 nm and beam divergence of ∼3 mrad were used, and the current in the probe was monitored and held constant at ∼1 nA.
Quantitative x-ray microanalysis and thickness determination using ζ factor
Authors: Watanabe M. , Horita Z. , Nemoto M. 
Published: June 2020

X-ray absorption in quantitative x-ray microanalysis of thin specimens may be corrected without knowledge of thickness when the extrapolation method or the differential x-ray absorption (DXA) method is used. However, there is an experimental limitation involved in each method. In this study, a method is proposed to overcome such a limitation. The method is developed by introducing the ζ factor and by combining the extrapolation method and DXA method. The method using the ζ factor, which is called the ζ-DXA method in this study, is applied to diffusion-couple experiments in the Ni-Al system.For a thin specimen where incident electrons are fully transparent, the characteristic x-ray intensity generated from a beam position, I, may be represented as I = (NρW/A)Qωaist.
Platform wars: Macintosh-based digitization systems
Authors: Krivanek O. L. , Hunt J. A. 
Published: June 2020

Improvements over the past few years in essentially all modern operating systems coupled with the blurring of the boundaries between mainframes, workstations, and personal computers make the choice of platform often one of personal preference other than of necessity. A decade ago there were very distinct differences between the features offered by IBM PC and clones, the Apple Macintosh, and UNIX workstations. These differences included price, processing performance, OS features, look and feel, graphical capabilities, memory and disk limitations, networking capabilities, ease-of-use, system stability, development tools, etc. Since then many of these distinguishing differences have evaporated making platform selection a more subtle issue, but also much less important. However, there are still a great many users that tend to make such decisions based on their “religious” preference of platform rather than based on objective information.How does one choose the appropriate platform for image acquisition and processing? The question should first be - “What software packages do what is needed?” From this list the choice of platform can be narrowed.
Software tools for 4D live cell microscopy
Authors: Thomas C. , DeVries P. , Hardin J. , White J.G. 
Published: June 2020

The Integrated Microscopy Resource has developed a trio of Macintosh-based software tools which allow the user to collect digital 4D microscopy (3D over time) of live cells. To demonstrate the program, high-resolution Nomarski DIC images were collected from an inverted microscope using a video camera. The output of the camera can be averaged and contrast-enhanced before the resulting signal is digitized using a framegrabber card installed in a Macintosh computer (Figure 1). Collection, subsequent processing, and analysis of the resulting data sets are handled by the following three software tools:4D Acquisition Software - This IMR-designed software system is based on the popular shareware image processing program “NIH-Image” (author Wayne Rasband, NIH) and controls the actual image acquisition through a series of graphic user interfaces. A framegrabber card, a stage drive motor, and an illumination shutter are manipulated to allow the imaging of either a single focal-plane of the specimen over time, or the acquisition of 3-dimensional volumes at each timepoint. After selecting the top and bottom of the sample, the user can specify the number of focal planes to acquire, the increment for the focus motor between focal planes, the number of timepoints to collect, and a file format in which to save the images. The software will automatically move through the sample from the top to the bottom gathering images of each focal plane as it goes. The result is a stack of images representing the 3D structure of the sample. The software will wait a defined amount of time and the process will be repeated for as many timepoints as the user has designated.
TEM characterization of CMR thin film on [001] SrTiO3 substrate
Authors: Wang Y.Y. , Gupta A. , Dravid V.P. 
Published: June 2020

Due to its potential magnetic device application, giant/colossal magnetoresistant (GMR or CMR) material, (bulk material as well as thin film), have been under intense investigation in recent years. In the bulk material, the changes of the resistivity under 4T magnetic field is about 80% at the metal-insulate transition temperature for La0.7Ca0.3MnO3 (LCMO). In 1994, S. Jin et al reported thousandfold change in resistivity in magnetoresistive La-Ca-Mn-0 films on a LaAlO3 substrate. It is suspected that such a large magnetoresistivity change in the thin film is due to the defect structure in the epitaxially grown thin film.The base structure of LCMO is an MnO6 octahedral perovskite cubic structure. Because of its strong static Jahn-Teller (JT) distortion, the compound is metrically orthorhombic, with a∼b∼√2 ap and c∼2ap where ap is the lattice constant for the base cubic structure. X-ray diffraction study on this compound shows that it belongs to Pnma space group.
Site occupancy in gamma alumina
Authors: Bateman C. A. , Ringwelski A.Z. , Broach R.W. 
Published: June 2020

Gamma (γ) alumina is referred to as a defect spinel because it has a tetragonally distorted spinel structure (AB2O4) and an insufficient number of cations to fill all cation sites. In the spinel structure, the oxygen lattice is cubic close packed with A- and B-site cations in tetrahedral and octahedral coordination, respectively. The 2l⅓ Al atoms per unit cell of γ alumina can distribute themselves across 16 octahedral and 8 tetrahedral sites.The literature differs on where the 2⅔ cation vacancies per unit cell are located. Wilson and McConnell proposed that the vacancies in γ alumina, as first formed by calcining boehmite, are predominantly on the tetrahedral lattice but, with further heat treatment, move to occupy random positions on both octahedral and tetrahedral lattices. One study using NMR showed that the vacancies lay exclusively on the tetrahedral lattice, independent of the calcination temperature. A more-recent study using Rietveld refinement of powder neutron diffraction data suggested that both octahedral and tetrahedral lattices were partially occupied.
Seminal Phagocytes Detection at Light-Microscopy Level using Three Different Techniques
Authors: Benítez L. A. , Díaz O. G. , Eguía R. M. M. , Gallegos M. G. A. 
Published: June 2020

The phagocytes are normally present in the conective tissue at different organs, and their number increased in immunological or inflammatory processes. In these cases, they are present too in corporal fluids.The presence of phagocytes in semen was referred by several authors, but that phenomenon has not been suficiently analysed. At smear Papanicolaou stained analysis, the seminal phagocytes can be inadverted thus, their relationship to the male infertility or another reproductive tract pathology can not be established.In this study we implemented three techniques to detect the presence of phagocytes in semen of 28 infertile patients: Myeloperoxidase for polymorphonuclears (leukocyte), Neutral red for macrophages and the semithin sections analysis at light microscopical level of the seminal pellet obtained by centrifugation and included in epoxyresin.
Bacterioids in the Rectal Organ of the Lantern Dug Pyrops Candelaria Linn (Homoptera: Fulgoridae)
Authors: Cheung W.W.K. , Wang J.B. 
Published: June 2020

The lantern bug harbours three symbionts, namely a, x and i in its body. These microorganisms are supposed to be transmitted transovarially to the future progeny. The x-symbionts are found in a special pair of organs called the x-organ which bulges to form a rectal organ in adult females. The purpose of this study is to investigate into the fine structure of the x-symbionts. This will serve as a basis for understanding the interactions of this microorganism with its host.The rectum of the lantern bug Pyrops candelaria Linn, was dissected out in buffered insect saline and fixed in 2.5% glutaradehyde in 0.1M sodium cacodylate buffer (pH 7.2) for 1 hr. The rectal organ was subsequently post-fixed in 1% osmium tetroxide (pH 7.2) and dehydrated in alcohol/acetone series. These were blocked in Spurr resin and cut with a Reichert Ultratome. Sections were stained with uranyl acetate and lead citrate and examined with a JEOL JEM-1200EX electron microscope. Thick sections (1 μn) were stained with 1% toluidine blue and examined under a Nikon Optiphot light microscope.
Attachment, entry, and destruction of cultured human B-lymphocytes by the lyme-disease spirochete borrelia burgdorferi
Authors: Fischer Elizabeth R. , Dorward David W. 
Published: June 2020

The most prevalent tick-borne disease in the United States, Lyme disease, is caused by the spirocheteBorrelia burgdorferi. Studies have suggested that Lyme disease spirochetes, like other bacteria, may enter host cells thereby evading the immune system.In order to investigate possible interactions between Lyme disease spirochetes and immune system cells, we co-incubatedB. burgdorferistrain Sh-2-82 with cultured human B- and T-cells (TIB-215 and H9, ATCC, respectively) and primary lymphocytes at an MOI of 100:1.Nomarski interference microscopy revealed that as early as 10 minutes after coincubation, as previously described with other cell lines, low passage spirochetes (<8 in vitro passages) attached tip first to the B-cells and then invaded the B-cells (Fig. 1,4). Scanning electron microscopy revealed that by 24 hours post-infection, 90+% of B-cells had spirochetes attached to their surfaces (Fig.2). Transmission electron microscopy suggested that intracellular spirochetes may exist both in vacuoles and free in the cytoplasm of primary lymphocytes (Fig. 3a-b).
Evaluation of alternative fixatives/protocols for the ultra-structural preservation of fast and slow growing mycobacteria
Authors: Hayes S. F , Small P. L. C. 
Published: June 2020

Various fixation formulas and protocols were examined to determine a routinely optimal fixation of Mycobacterial species in and out of tissues. These were evaluated by TEM and compared to results obtained using freeze substitution methods upon other Mycobacteria such as Mycobacterium aurum CIPT 1210005, M. fortuitum, M. phlei 425, M. kansasii and M. thermoresistible ATCC 19527Samples consisted of two slow growing mycobacterial species, both human pathogens; Mycobacterium tuberculosis, grown in M7H9 broth, and Mycobacterium marinum (1218 R & S variants), grown on M7H10 agar, with the latter also grown in tissue culture, and in guinea pig skin. Fixatives included: (1) glutaraldehyde/parafoimaldahyde/tannic acid in a phosphate/sucrose buffer, (2) paraformaldehyde/polylysine/periodate/glutaraldehyde (PLPG) in phosphate buffer followed by tannic acid and reduced osmium respectively, (3) PLP followed by tannic acid only without osmium, and (4) fixative 84-40 containing carbodiimide, glutaraldehyde and ruthenium red. Protocols varied in the length of time for fixation, types of buffers, solvents and in embedding schedules for Spurr's low viscosity resin.
New insights into the Ras onco-protein and its interactions with the Raf-1-1 kinase
Authors: Campbell Sharon , Mott Helen , Zhong Sheng , Drugan Jonelle , Carpenter John 
Published: June 2020

The Ras proteins are members of a large superfamily of nucleotide-binding proteins that cycle between active GTP- and inactive GDP-bound states. They are positively regulated by guanine nucleotide exchange factors (GEFs) that promote formation of the active GTP-bound state and negatively regulated by GTPase activating proteins (GAPs) that stimulate formation of the inactive GDP-complexed protein. Structural mutations that activate Ras oncogenic potential either impair GAP-stimulated GTPase activity or promote enhanced intrinsic nucleotide exchange. The net result of either biochemical effect is to favor elevated levels of Ras-GTP in vivo.We are investigating selected Ras variants containing substitutions at conserved sites thought to be important for guanine nucleotide binding, GTP hydrolysis, GTP/GDP interconversion and protein recognition, to better understand the role of these conserved amino acids in Ras-mediated signal transduction. Recent studies conducted at the U. of North Carolina will be presented, where we have characterized a novel activating mutation in Ras using multi-dimensional NMR spectroscopy and established a region involved in direct interaction with guanine nucleotide exchange factors.
Visualization of individual astrocytes in three-dimensional cerebellar tissues using green fluorescent protein
Authors: Andersen M. D. , Szarowski D. H. , Turner J. N. , Shain W. 
Published: June 2020

The central nervous system is a complex structure traditionally studied through selective stains and two-dimensional images of fixed tissues. A long term goal of this laboratory is the study of dynamic cellular interactions in three dimensional tissues such as organotypic cultures. Due to the large volume of tissue, traditional microscopy methods contain excessive out-of-focus data making it difficult to observe clearly specific cellular interactions. The visualization of morphological changes in specific cells in living, three-dimensional tissues is commonly done with vital dyes. An alternate approach is labeling individual astrocytes with Green Fluorescent Protein (GFP) and injecting them into organotypic cultures.GFP is a naturally fluorescent protein originally isolated from the jellyfish Aequorea victorea. To label individual astrocytes, LRM55 astroglial cells were transfected with GFP using calcium phosphate. The percentage of stable transfectants was low (< 1%) resulting in expression of varying amounts of GFP, as seen in Figs 5 and 6.
TEM comparison of osmium vs osmium with potassium ferricyanide secondary fixatives and the impact of secondary fixative temperature on tissue preservation/contrast quality
Authors: Horn J. W. , Dovey-Hartman B. J. , Meador V. P. 
Published: June 2020

Osmium tetroxide (OsO4) is a universally used secondary fixative for routine transmission electron microscopic evaluation of biological specimens. Use of OsO4 results in good ultrastructural preservation and electron density but several factors, such as concentration, length of exposure, and temperature, impact overall results. Potassium ferricyanide, an additive used primarily in combination with OsO4, has mainly been used to enhance the contrast of lipids, glycogen, cell membranes, and membranous organelles. The purpose of this project was to compare the secondary fixative solutions, OsO4 vs. OsO4 with potassium ferricyanide, and secondary fixative temperature for determining which combination gives optimal ultrastructural fixation and enhanced organelle staining/contrast.Fresh rat liver samples were diced to ∼1 mm3 blocks, placed into porous processing capsules/baskets, preserved in buffered 2% formaldehyde/2.5% glutaraldehyde solution, and rinsed with 0.12 M cacodylate buffer (pH 7.2). Tissue processing capsules were separated (3 capsules/secondary fixative.solution) and secondarily fixed (table) for 90 minutes. Tissues were buffer rinsed, dehydrated with ascending concentrations of ethanol solutions, infiltrated, and embedded in epoxy resin.
Shallow drain extension by angled ion implantation
Authors: Alvis Roger , Liming Scott , Griffin Peter 
Published: June 2020

In a technology driven enterprise, such as the semiconductor industry, pure research and development often overshadows manufacturing concerns. Typically, “discovery” is the result of miniaturization efforts with integration into existing process flows a secondary concern. However, it is often the case that fabrication of devices is complicated by next generations of technologies. Since revenue and profits are ultimately determined by the speed and ease with which a wafer may be processed, the streamlining of process flows assumes a certain level of importance. In this work, we describe the construction and microstructural characterization of a simple spacerless metal-oxide semiconductor (MOS) transistor with a self-aligned shallow drain extension.Transistor structures were fabricated at Stanford University's Center for Integrated Systems usinga single masking step to pattern the gate mask for the self-aligned structures. A 200Å gate oxide wasgrown and a 3000Å polysilicon blanket film was subsequently deposited on the wafer. Thepolysilicon was patterned into an array of 2.0μm lines and 3.0μm spaces.
In situ TEM observations of melting in nanosized eutectic Pb-Cd inclusions embedded in Al
Authors: Hagège S. , Dahmen U. , Johnson E. , Johansen A. , Tuboltsev V.S. 
Published: June 2020

Small particles of a low-melting phase embedded in a solid matrix with a higher melting point offer the possibility of studying the mechanisms of melting and solidification directly by in-situ observation in a transmission electron microscope. Previous studies of Pb, Cd and other low-melting inclusions embedded in an Al matrix have shown well-defined orientation relationships, strongly faceted shapes, and an unusual size-dependent superheating before melting.[e.g. 1,2].In the present study we have examined the shapes and thermal behavior of eutectic Pb-Cd inclusions in Al. Pb and Cd form a simple eutectic system with each other, but both elements are insoluble in solid Al. Ternary alloys of Al (Pb,Cd) were prepared from high purity elements by melt spinning or by sequential ion implantation of the two alloying additions to achieve a total alloying addition of up to lat%. TEM observations were made using a heating stage in a 200kV electron microscope equipped with a video system for recording dynamic behavior.
Effect of electron irradiation on the 3C-4H transformation in a Co-Fe alloy
Authors: Allen Charles W. , Mori Hirotaro 
Published: June 2020

In general, irradiation of materials by high energy electrons, protons or neutrons has been shown to stabilize the existing microstructure against subsequent martensitic transformation. Alloys which have been studied include the binary intermediate phases NiTi and Ni63Al37 and ternary phases between Cu37,5Al62.5 and CU63.6Al36.4 as well as the intermetallic Cu69.01Al17.92 Zn12.17. In these materials, the martensitic transformations are known to be sensitive to small changes in chemical composition and to the degree of long range order. In addition, one should expect the kinetics of martensitic transformations to be sensitive to other forms of structural damage introduced during irradiation also. This spectrum of irradiation-induced phenomena renders the interpretation of results in studies of such concentrated binary and ternary phases rather complicated, therefore.We present here the preliminary results of a study of the effect of electron irradiation on the character of
the martensitic transformation in a relatively dilute terminal solid solution of Co+5.75 wt pet Fe, similar in
composition to that employed for studies of the transformation mechanism itself.
An Application of a Method for Correlating Mechanical Property Changes with Microstructural Changes in Ion-Irradiated Specimens
Authors: Rice P. M. , Stoller R. E. 
Published: June 2020

A method for correlating mechanical property changes and microstructural changes as a function of depth in ion irradiated specimens has been applied to a series of model pressure vessel steels. The technique employs nanoindentation with very small indent depths, on cross sectional specimens, to measure changes in hardness with sub-micron spatial resolution. Conventional TEM imaging of the cross sectional specimens allows the investigation of the defect microstructure as a function of depth below the original irradiated surface. For ion irradiations (implantations) the dose varies as a function of depth in the specimen and can be calculated with reasonable accuracy using TRIM calculations. Thus changes in both hardness and defect microstructure can be measured and correlated, over a range of doses, from a single specimen.The technique has been applied to a set of model ferritic pressure vessel alloys to study the effect of various solutes on embrittlement. 2.5 MeV He ion irradiation was used to produce qualitatively similar microstructural features to those created in a nuclear reactor environment allowing the study to be carried out without the added complications associated with radioactive specimens. Figure la is an SEM image showing a set of nano-indents that starts on the left, beyond the end of range of the ions which is easily seen as the dark band. The indents eventually cross the thin oxide that marks the original irradiated surface (the white line) and enter the Fe electroplating seen here as the fine grained material at the bottom of the images. Figure lb is a higher magnification SEM image of the same indents showing the three-sided pyramid shaped indents reflective of the Berkovich diamond used in nanoindenting. Each of these residual indents is the result of a multipule indent process. The first indent is 50nm deep to acquire the sub-micron resolution hardness data, and the second is twice as deep (thus twice as wide) to clearly mark the position of the shallower indent before moving to the next position. Figure 2a is a bright-field TEM micrograph showing the defect microstructure of the entire irradiated region of an Fe + low N alloy, taken with g = {330} such that the dislocation loops appear dark. Figure 2b is a plot of the actual change in hardness, AH, as a function of depth below the original irradiated surface at the same scale, and for the same alloy shown in figure 2a.
Nuclear coiled bodies and the nucleolus
Authors: Brasch K. , Williams J. , Gallo D. , Lee T. , Ochs R. L. 
Published: June 2020

Though first described in 1903 by Ramon-y-Cajal as silver-staining “accessory bodies” to nucleoli, nuclear bodies were subsequently rediscovered by electron microscopy about 30 years ago. Nuclear bodies are ubiquitous, but seem most abundant in hyperactive and malignant cells. The best studied type of nuclear body is the coiled body (CB), so termed due to characteristic morphology and content of a unique protein, p80-coilin (Fig.1). While no specific functions have as yet been assigned to CBs, they contain spliceosome snRNAs and proteins, and also the nucleolar protein fibrillarin. In addition, there is mounting evidence that CBs arise from or are generated near the nucleolus and then migrate into the nucleoplasm. This suggests that as yet undefined links may exist, between nucleolar pre-rRNA processing events and the spliceosome-associated Sm proteins in CBs.We are examining CB and nucleolar changes in three diverse model systems: (1) estrogen stimulated chick liver, (2) normal and neoplastic cells, and (3) polyploid mouse liver.