bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of phases in an as-cast Mo-B-Si alloy by WDS EPMA
Authors: Nunes C. A. , Fournelle J.H. , Perepezko J.H. 
Published: June 2020

EPMA experiments have been carried out to support an extensive study involving phase equilibria, solidification pathways and diffusion in Mo-rich Mo-B-Si alloys. In this work we have characterized the phases present in an as-cast 60Mo-30B-10Si (at%) alloy by WDS EPMA in order to provide further information to understand some anomalous backscattered electron images of this alloy.The alloy was produced by arc-melting pure Mo, B and Si under argon. The EPMA analysis was carried out in a CAMECA SX-50 EPMA on a polished and flat surface of the material. In order to avoid additional absorption of the B-Kex radiation the sample was not coated.The analysis of boron in the presence of Mo presents serious interference between the Mo My line and the B-Koc line (Figure 1).
ALCHEMI of NbCr2/V C15-structured laves phase
Authors: Kotula P.G. , Anderson I.M. , Chu F. , Mitchell T.E. , Bentley J. 
Published: June 2020

Laves-phase intermetallics are of potential interest for use as high temperature structural materials, of which NbCr2-based C15-structured Laves phases are particularly attractive. Vanadium-alloyed NbCr2 Laves phases have been studied. The defect mechanism of a ternary Laves phase is crucial to understanding its physical metallurgy and deformation behavior. It is suggested based on the Nb-Cr-V phase diagram and first-principles total energy and electronic structure calculations for NbCr2 that V should occupy the B sites in C15-structured AB2. In this paper, ALCHEMI is employed to examine this assumption for one composition of a V-alloyed NbCr2 Cl5 Laves phase.A Nb-Cr-V alloy of composition Nb33Cr42V25 was prepared by arc-melting followed by annealing at 1400°C for 120 h. Specimens were prepared for microanalysis by cutting 3 mm discs followed by dimpling and ion milling. Energy-dispersive X-ray (EDX) spectra were acquired with a Philips CM30 operating at 300 kV and equipped with a Kevex Quantum detector. Fourteen spectra were collected near <014> over a range of {400} excitations between symmetry and beyond {12 0 0}.
Analytical Electron Microscopy of nanometer-size precipitates in al alloys with a 200-kV field-emission TEM
Authors: Howe J. M. , Ringer S. P. , Muddle B. C. , Polmear I. J. 
Published: June 2020

Certain trace elements are known to have a pronounced effect on the nucleation kinetics of metastable phases in Al alloys. This provides many opportunities for alloy design. Understanding the role of trace elements in the precipitation process is difficult because they are typically present at levels of less than 0.1 at.% and involve early stages of clustering or segregation to precipitates. This paper presents recent results from the application of a 200 kV thermal field-emission gun (FEG) transmission electron microscope (TEM) to study trace element additions and the early stages of precipitation in Al alloys, using the case of an experimental alloy designated ALMAGEM as an example.An Al-2.41Cu-0.34Mg-0.lSi-0.04Ge alloy was cast into a book mold, homogenized, solution treated at 525°C, water quenched and aged for 12.5 h at 170°C to peak hardness. Disks 3 mm in diameter were electropolished in a HNOs/methanol solution and examined at 200 kV in a JEOL 2010F FEG TEM with a high-tilt (±30°) pole piece.
Color image analysis in optical microscopy
Authors: Laroche Sylvain 
Published: June 2020

Most of the applications in microscopic image analysis are still solved by a heuristic method that focuses on the specificity of each problem. This is particularly true for applications involving color images. Because of this, the design of robust algorithms has remained time consuming and is usually performed by an image analysis expert with many years of experience. How then can the knowledge of the expert be transferred to the less specialized microscopist? How can the specificity of a typical application be related to general color image analysis tools?Only a general approach can work towards decreasing the heuristic aspect of the design phase and help the common user perform image analysis without the assistance of an expert. To illustrate such an approach, two typical applications, one in material science, and the other in the biomedical field are presented:
Practical considerations and applications of digital imaging in a core microscopy facility
Authors: Price R.L. 
Published: June 2020

The Integrated Microscopic Analysis Facility (IMAF) at the University of South Carolina School of Medicine is a core
research and imaging facility that provides service for the faculty, staff and students of the medical school and associated hospitals. The IMAF currently houses one scanning and two transmission electron microscopes, a confocal scanning laser microscope, and several image processing computers and programs. While not yet totally converted to digital technology, we have been successful in introducing digital imaging to several areas of our imaging capabilities during the last few years. The purpose of this abstract and subsequent presentation is to present some practical considerations and problems we have encountered in the conversion of the IMAF to digital imaging microscopy, and to present brief results from some projects which were not possible before the introduction of digital imaging to the facility.There is little doubt that in the past few years one of the major advances for those of us who work in the areas of light and electron microscopy has been the development of digital imaging technology.
In-situ and ex-situ AFM imaging of μN load indents on silicate glass/alumina interfaces
Authors: Zagrebelny A. V. , Lilleodden E. T. , Nelson J. C. , Ramamurthy S. , Carter C. B. 
Published: June 2020

Contact which only involves a small volume of material is becoming increasingly important to many industries including micromachines, microelectronics, and magnetic recording. The ability to characterize surface roughening on the micro- and nanoscopic scale is invaluable in understanding microplasticity due to indentation, scratches, wear, fatigue and epitactic mismatch. It has been demonstrated that AFM studies are appropriate for developing a mechanistic approach to μN load indentation analysis since they allow deformation volumes and residual depths to be measured and characterized directly and unambiguously.In the present study, interfaces between silicate glass and single-crystal α-Al2O3 have been studied using AFM and nanoindentation. The interfaces between the glass and the crystalline grains were prepared by growing films of anorthite (CaAl2Si2O8) composition with thickness ranging 100-200 nm on single-crystal sapphire substrates of {1120} (A-plane) and {1102} (R-plane) crystallographic orientations by pulsed-laser deposition (PLD). Some specimens were subjected to heat treatments in a conventional box furnace causing films to dewet the substrates. Fig. 1 shows schematically the morphology of the dewetted film which has resulted in the formation of distinctive islands, 0.5-2 μm in size. Both types of specimens were tested with two different micro/nanomechanical testers.
Time-resolved high-resolution electron microscopy of grain migration process in MgO films
Authors: Kizuka T. , Iijima M. , Tanaka N. 
Published: June 2020

High-resolution electron microscopy (HREM) has been employed intensively to analyze the atomic structures of grain boundaries and interfaces having two dimensional structures inside polycrystalline and composite materials. Furthermore time-resolved HREM (TRHREM) is required to analyze the behavior of grain boundaries and interfaces at atomic scale. The grain boundary migration, which is a typical grain boundary behavior, is a fundamental process relating to structural stability of polycrystalline materials. The mechanism of the migration has been still unknown.In the present study, the variation of atomic arrangement at the grain boundary migration of a MgO [001]Σ5 boundary was analyzed by TRHREM.Magnesium oxide polycrystalline films were prepared by vacuum-deposition on air-cleaved (001) surfaces of sodium chloride at 300°C. TRHREM was carried out at room temperature using a 200-kV electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder. The spatial resolution of the system was 0.2 nm at 200 kV and the time resolution was 1/60 s. Electron beam density was 30 A/cm2.
SIMS direct ion imaging in the mineralogical sciences
Authors: McMahon G. , Cabri L. J. 
Published: June 2020

The use of secondary ion mass spectrometry (SIMS) has enjoyed increasing popularity in the mineralogical sciences owing to its high sensitivity to all elements in the periodic table with detection limits in the parts per million to parts per billion regime, coupled with the ability to display maps of elemental distribution at these detection levels with a spatial resolution of 1 μm. A description of the technique and its application to a wide variety of mineralogical problems has recently been reviewed.The drawback of SIMS is the rather complicated nature of quantification schemes necessitated by sample matrix effects, which refer to differences in the sensitivity for a given element in samples of different composition. These differences result from changes in the ionization efficiency and sputtering yield (sample matrix specific) as well as changes in secondary ion transmission and ion collection efficiencies (instrument specific). Therefore, the use of matrix-matched standards of known concentration is required to establish a calibration factor known as the relative sensitivity factor (RSF) which can be used to convert the experimentally measured secondary ion intensity into concentration values. Furthermore, the effect of changes in ion intensity caused by variations in primary beam current or analysis at different sample positions is removed by normalization to an ion species which represents the matrix material.
Light – microscopic analysis of the physical properties of cytoplasm in living cells
Authors: Hori Masatoshi , Jones Jeffrey D. , Janson Lee , Ragsdale Keith , Luby-Phelps Katherine 
Published: June 2020

We have used a variety of optical techniques to explore the intracellular constraints on diffusion, cytoplasmic compartmentalization and biomechanics of living tissue culture cells. Fluorescence ratio imaging measurements of solvent viscosity in single cells indicate that the solvent viscosity of cytoplasm does not differ detectably from bulk water. Nevertheless, data obtained by fluorescence recovery after photobleaching (FRAP) of inert tracer molecules suggest that macromolecular crowding and molecular sieving retard the long-range translational diffusion of protein-sized molecules from 4 to 50-fold relative to their diffusion in dilute aqueous solution.Transient binding interactions with intracellular components may additionally retard the diffusion of proteins. Recent FRAP studies of fluorescent analogs of calmodulin suggest that as little as 5% of this protein is freely diffusing, even in unstimulated cells where intracellular [Ca2+] is below the threshold for activation of calmodulin binding to calcium-dependent targetsin vitro. Preliminary data show that binding is mitigated or abolished by charge reversal mutations in the central helix of calmodulin or by a point mutation in calcium binding loop 4 that greatly reduces the affinity of calmodulin for Ca2+.
Hepatocyte ultrastructural alterations in perimetastatic areas
Authors: Finol H. J. , Correa M. E. , Sosa L.A. , Márquez A. , Díaz N.L. 
Published: June 2020

In classical oncological literature two mechanisms for tissue aggression in patients with cancer have been described. The first is the progressive invasion, infiltration and destruction of tissues surrounding primary malignant tumor or their metastases; the other includes alterations produced in remote sites that are not directly affected by any focus of disease, the so called paraneoplastic phenomenon. The non-invaded tissue which surrounds a primary malignant tumor or its metastases has been usually considered a normal tissue . In this work we describe the ultrastructural changes observed in hepatocytes located next to metastases from diverse malignant tumors.Hepatic biopsies were obtained surgically in patients with different malignant tumors which metatastized in liver. Biopsies included tumor mass, the zone of macroscopic contact between the tumor and the surrounding tissue, and the tissue adjacent to the tumor but outside the macroscopic area of infiltration. The patients (n = 5), 36–75 years old, presented different tumors including rhabdomyosarcoma, leiomyosarcoma, pancreas carcinoma, biliar duct carcinoma and colon carcinoma. Tissue samples were processed with routine techniques for transmission electron microscopy and observed in a Hitachi H-500 electron microscope.
Spermatic multinucleation in infertile agriculture workers exposed to carbofuranyl pesticide
Authors: Gallegos de L. G. , Arizpe S. M.M. , Alvarado C. L.E. , Ramirez B. E. 
Published: June 2020

It is known that the exposure to gonadotoxic agents cause male infertility in agricutural workers. Pesticides provoke a detrimental effect on the spermatogenesis characterized by low count of sprematozoa, as well as sperm motility and morphology alterations. Simultaneosly an increase in FSH seric levels is present.The semen analysis was proposed in 1975 to detect sperm quality and function alteration induced by chemical agents. There are many morphologic anomalies related to the noxious action of some gonadotoxic agents, ie. head deformities, microcephalia, tail defects, etc.We detected in our laboratory a pair of cases of infertile patients, that presented high levels of teratozoospermia with a high percentage of multinucleated spermatozoa and spermatids, and referred exposure to Carbofuranyl (Furadan 300). Since this agent has not been classified as gonadotoxic, we tried to show it's posible causal relationship with spermatic multinucleation phenomenon observed and the fertility of these patients.
Movement of spotted fever rickettsiae through tick host cells in vitro
Authors: Munderloh U. G. , Hayes S. F. , Cummings J. , Kurtti T. J. 
Published: June 2020

Spotted fever group (SFG) rickettsiae are obligate intracellular prokaryotes that include tick-borne pathogens of animals and man as well as organisms that live in symbiotic association with their tick hosts. A striking feature of the behavior of pathogenic rickettsiae in the vertebrate is their ability to quickly disseminate between cells from the original site of entry shortly after infection, and before severe lesions are detected. Similarly, ticks become systemically infected with SFG rickettsiae, indicating that an efficient mechanism of dispersal also exists in the vector. This is accomplished despite the fact that rickettsiae are not motile.Kadurugamuwa et al. (1991) have used light and electron microscopy to show that Shigella flexneri utilize host cytoskeletal components to travel through cytoplasmic extensions and penetrate into neighboring cells. Using mammalian cells cultured in vitro, Heinzen et al. (1993) have demonstrated that SFG rickettsiae cause host cell actin polymerization at one rickettsial pole causing them to be propelled through the cytoplasm, and to transfer rapidly from cell to cell.
Emerging applications of fluorescence spectroscopy to cellular imaging: Long-lifetime metal-ligand probes, multi-photon excitation, light quenching, and lifetime imaging
Authors: Lakowicz J. R. 
Published: June 2020

The applications of advanced concepts in fluorescence spectroscopy are increasing rapidly due to developments in probe chemistry and optical technology. In this talk we describe recent developments and their applications to cellular imaging.While there exists thousands of fluorescent probes, almost all display lifetimes from 1 to 10 ns. These ns decay times are comparable to that found for cellular and tissue autofluorescence, which typically limits the sensitivity of most measurements. The lanthanides display long decay times, but their emission is unpolarized and cellular labeling is difficult. To circumvent these difficulties we are developing metal-ligand complexes as typified by Ru(bpy)3 and its conjugtable derivatives (Figure 1). The asymmetrical complexes display high anisotropy. The high anisotropy, combined with decay times of 400 ns or longer (Figure 2) results in probes capable of measuring microsecond macromolecular hydrodynamics. The use of long lived probes allows gated detection to avoid the prompt autofluorescence. Additionally, the metal-ligand probes are highly photostable.
CCD cameras facilitate the imaging of small gold particles in immunogold-labelled ultrathin cryosections
Authors: Ackerley C.A. , Becker L.E. , Tilups A. , Rutka J.T. , Mancuso J.F. 
Published: June 2020

Immunogold labelled ultrathin cryosections have proven themselves invaluable in subcellular localizations of many epitopes. As there are no embeddents to block an antibody‘s access to an epitope beyond physical size or chemical alteration by primary fixation, immunogold labelling density is increased dramatically with smaller (>5nm) gold-ligand complexes. Takizawa and Robinson have elegantly demonstrated penetrations in excess of 1μm using 1.4nm gold-Fab conjugates, while 5nm IgG gold particles only partially penetrated the surface and l0nm IgG gold particles labelled the surface. In order to visualize the 1.4nm gold-Fab particles silver enhancement was required leading one to doubt the viability of doing any quantitation.Modern CCD cameras provide an effective alternative method of data collection to photographic plates with their ability to record 1000 × 1000 pixel digital images. Using a simple sharpen filter and contrast enhancement, 1.4nm gold Fab particles are easily resolved on thin films. Problems arise when using this small a particle on conventionally stained immunogold labelled cryosections.
Development of a cryosection EM autoradiography technique and its application for the subcellular localization of receptors
Authors: Na C.-L. , Hagler H. K. , Muntz K. H. 
Published: June 2020

Recent progress in immunocytochemistry and cryo-techniques has made it possible to study receptor localization at the subcellular level. For many receptor-ligand systems suitable antibodies are not available and it would be more appropriate to use radioligands to study these receptors. Although fresh frozen sections have been widely used in light microscopy (LM) autoradiography studies, to our knowledge, no one has established a technique using electron microscope (EM) autoradiography with ultrathin frozen sections.Unlike conventional EM approaches which can extract many biological molecules during dehydration and plastic embedding steps, we have adopted the method of Tokuyasu combined with LM autoradiography protocol for frozen sections to develop a new EM autoradiography technique using ultrathin frozen sections. Heart blocks were fixed in 2% periodate-lysine-paraformaldehyde (PLP) and 0.1% glutaraldehyde (GA), sucrose infused, and frozen in liquid nitrogen. They were sectioned in a Reichert Ultracut S cryo-microtome equipped with a Reichert FCS cryo-unit.
Effects of substrate orientation on growth of epitaxial layers
Authors: Hsu Y. , Kuan T. S. , Wang W. I. 
Published: June 2020

Semiconductor superlattices or epitaxial overlayers have so far been grown mostly on (100)-oriented substrates. It has long been suspected that growth on surfaces such as (m11) could produce equally good or better epitaxial layers. In this work, we have systematically tested the growth of multi- or single-layered structures, including the GaAs/AlAs, AlAs/Ge, and GaAs/Si systems, on surfaces of different orientations. The crystallinity and defect mechanisms in the layers grown on (100), (311), and (511) surfaces at different temperatures were compared. In most cases we found that (311) surfaces can produce epitaxial layers as good as on (100) surfaces.Perfect lattice-matched GaAs/AIAs superlattices were grown on (311)A-, (311)B-, and (100)-oriented GaAs substrates. Superlattices with good layer morphology were achieved on all three surfaces at 600°C. Fig. 1(a) shows an image of a typical GaAs/AIAs superlattice grown on a (311)B surface. This superlattice exhibits sharp interface abruptness as indicated by the high-order satellites observed in the diffraction pattern in Fig. 1(b).
Determination of arsenic atom distribution arsenic doped silicon using HOLZ-line analysis
Authors: Kikuchi Y. , Hashikawa N. , Uesugi F. , Wakai E. , Watanabe K. , Hashimoto I. 
Published: June 2020

In order to measure the concentration of arsenic atoms in nanometer regions of arsenic doped silicon, the HOLZ analysis is carried out underthe exact [011] zone axis observation. In previous papers, it is revealed that the position of two bright lines in the outer SOLZ structures on the[011] zone axis is little influenced by the crystal thickness and the background intensity caused by inelastic scattering electrons, but is sensitive to the concentration of As atoms substitutbnal for Siatomic site.As the result, it becomes possible to determine the concentration of electrically activated As atoms in silicon within an observed area by means of the simple fitting between experimental result and dynamical simulatioan. In the present work, in order to investigate the distribution of electrically activated As in silicon, the outer HOLZ analysis is applied using a nanometer sized probe of TEM equipped with a FEG.Czodiralsld-gown<100>orientated p-type Si wafers with a resistivity of 10 Ώ cm are used for the experiments.TheAs+ implantation is performed at a dose of 5.0X1015cm-2at 25keV.
Time-resolved high-resolution electron microscopy of nanometer-scale electron beam processing of PbTe films
Authors: Kizuka T. , Tanaka N. 
Published: June 2020

Various kinds of nanometer scale processings are required to produce advanced materials, for example, nano-structured electric devices. Electron beam processing at nanometer scale using STEM and TEM, such as drilling and line-writing, is recently interested as a most useful method. Details of structural change during the processing should be elucidated at atomic resolution in order to establish the processing. In the present work we have processed lead telluride (PbTe) films with nanometer electron beam in a high-resolution transmission electron microscope and in-situ observed the variation of atomic arrangements during the processing.PbTe of 99.99% was vacuum-deposited on air-cleaved (001) surfaces of sodium chloride at room temperature. Time-resolved high-resolution electron microscopy was carried out at room temperature using a 200-kV electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder. The spatial resolution of thesystem was 0.2 nm at 200 kV and the time resolution was 1/60 s. Electron beam irradiation density was 120 A/cm2 at the processing and the observation.
Microstructure of aged Ni-Mo (Ni/Mo = 4) alloys containing Al
Authors: Shen Elaine , Brooks Charlie R. , Kenikt E. A. 
Published: June 2020

Ni-rich Ni-Mo alloys containing around 20 at. % Mo exist as a face-centered cubic, short-range ordered (SRO), solid solution (α) above around 868 °C, and transform to a long-range ordered (LRO), body-centered tetragonal structure (β) upon cooling slowly to below this temperature. Upon quenching, the α is retained, which can then be converted to β upon aging below 868 °C. The formation of the β structure induces considerable strengthening (e.g.. the hardness doubles), but is accompanied by embrittlement.A commercial alloy based on this composition is Hastelloy B2, and precautions are exercised in its use to prevent ordering and hence embrittlement. In a continuing effort to develop Ni-Mo alloys strengthened by ordering but with usable toughness, we have been examining the addition of Al to the base Ni-25 at. % Mo composition. Specimens containing 2. 5, 7 and 9 at. % Al, with Ni/Mo = 4.0, were made by arc melting the appropriate amounts of a Hastelloy B2 alloy and Al. The buttons were melted several times under an argon atmosphere.