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Microscopy and Microanalysis

Xueli Wang, Zhiqiang Xie, Huilan Huang, Zhihong Jia, Guang Yang, Lin Gu, Qing Liu
The morphology, composition, and structure of precipitates in an Al-Si-Mg-Hf alloy after heat treatment at 560°C for 20 h were studied by means of C s -corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectrometry (EDS), high-resolution transmission electron microscopy (HRTEM), and first-principle calculations. Precipitates with three kinds of morphologies were observed. The rectangular and square precipitates were predominantly (Si2-x Al x )Hf phases, while the nanobelt-like precipitate is the Si2Hf phase...
June 20, 2017: Microscopy and Microanalysis
Paul E Fischione, Robert E A Williams, Arda Genç, Hamish L Fraser, Rafal E Dunin-Borkowski, Martina Luysberg, Cecile S Bonifacio, András Kovács
This paper reports on the substantial improvement of specimen quality by use of a low voltage (0.05 to ~1 keV), small diameter (~1 μm), argon ion beam following initial preparation using conventional broad-beam ion milling or focused ion beam. The specimens show significant reductions in the amorphous layer thickness and implanted artifacts. The targeted ion milling controls the specimen thickness according to the needs of advanced aberration-corrected and/or analytical transmission electron microscopy applications...
June 19, 2017: Microscopy and Microanalysis
William J Kowalski, Fangping Yuan, Takeichiro Nakane, Hidetoshi Masumoto, Marc Dwenger, Fei Ye, Joseph P Tinney, Bradley B Keller
Biological tissues have complex, three-dimensional (3D) organizations of cells and matrix factors that provide the architecture necessary to meet morphogenic and functional demands. Disordered cell alignment is associated with congenital heart disease, cardiomyopathy, and neurodegenerative diseases and repairing or replacing these tissues using engineered constructs may improve regenerative capacity. However, optimizing cell alignment within engineered tissues requires quantitative 3D data on cell orientations and both efficient and validated processing algorithms...
June 19, 2017: Microscopy and Microanalysis
Shuang Liang, Ying Jie Niu, Kyung-Tae Shin, Xiang-Shun Cui
Coenzyme Q10 (Q10) plays an important role in the cellular antioxidant system by protecting the cells from free-radical oxidative damage and apoptosis. In the present study, we have investigated the effect of Q10 on the preimplantation development of porcine parthenogenetic embryos, as well as the underlying mechanism. The results showed that 100 μM was the optimal concentration of Q10, which resulted in significantly increased cleavage and blastocyst formation rates and improvement of blastocyst quality. Q10 improved the blastocyst hatching rate and cellular proliferation rate in hatching blastocysts and increased the expression of hatching-related genes...
June 7, 2017: Microscopy and Microanalysis
Gregory L Fisher, John S Hammond, Scott R Bryan, Paul E Larson, Ron M A Heeren
We present the first demonstration of a general method for the chemical characterization of small surface features at high magnification via simultaneous collection of mass spectrometry (MS) imaging and tandem MS imaging data. High lateral resolution tandem secondary ion MS imaging is employed to determine the composition of surface features on poly(ethylene terephthalate) (PET) that precipitate during heat treatment. The surface features, probed at a lateral resolving power of<200 nm using a surface-sensitive ion beam, are found to be comprised of ethylene terephthalate trimer at a greater abundance than is observed in the surrounding polymer matrix...
June 7, 2017: Microscopy and Microanalysis
Bastien Bonef, Hervé Boukari, Adeline Grenier, Isabelle Mouton, Pierre-Henri Jouneau, Hidekazu Kinjo, Shinji Kuroda
A detailed knowledge of the atomic structure of magnetic semiconductors is crucial to understanding their electronic and magnetic properties, which could enable spintronic applications. Energy-dispersive X-ray spectrometry (EDX) in the scanning transmission electron microscope and atom probe tomography (APT) experiments reveal the formation of Cr-rich regions in Cd1-x Cr x Te layers grown by molecular beam epitaxy. These Cr-rich regions occur on a length scale of 6-10 nm at a nominal Cr composition of x=0.034 and evolve toward an ellipsoidal shape oriented along directions at a composition of x=0...
June 7, 2017: Microscopy and Microanalysis
Sriram Vijayan, Joerg R Jinschek, Stephan Kujawa, Jens Greiser, Mark Aindow
Micro-electro-mechanical systems (MEMS)-based heating holders offer exceptional control of temperature and heating/cooling rates for transmission electron microscopy experiments. The use of such devices is relatively straightforward for nano-particulate samples, but the preparation of specimens from bulk samples by focused ion beam (FIB) milling presents significant challenges. These include: poor mechanical integrity and site selectivity of the specimen, ion beam damage to the specimen and/or MEMS device during thinning, and difficulties in transferring the specimen onto the MEMS device...
June 5, 2017: Microscopy and Microanalysis
Srinivas Subramaniam, Jennifer Huening, John Richards, Kevin Johnson
The xenon plasma focused ion beam instrument (PFIB), holds significant promise in expanding the applications of focused ion beams in new technology thrust areas. In this paper, we have explored the operational characteristics of a Tescan FERA3 XMH PFIB instrument with the aim of meeting current and future challenges in the semiconductor industry. A two part approach, with the first part aimed at optimizing the ion column and the second optimizing specimen preparation, has been undertaken. Detailed studies characterizing the ion column, optimizing for high-current/high mill rate activities, have been described to support a better understanding of the PFIB...
June 5, 2017: Microscopy and Microanalysis
Andreas Mittelberger, Christian Kramberger, Christoph Hofer, Clemens Mangler, Jannik C Meyer
Beam damage is a major limitation in electron microscopy that becomes increasingly severe at higher resolution. One possible route to circumvent radiation damage, which forms the basis for single-particle electron microscopy and related techniques, is to distribute the dose over many identical copies of an object. For the acquisition of low-dose data, ideally no dose should be applied to the region of interest before the acquisition of data. We present an automated approach that can collect large amounts of data efficiently by acquiring images in a user-defined area-of-interest with atomic resolution...
May 23, 2017: Microscopy and Microanalysis
Xavier Llovet, Francesc Salvat
The Monte Carlo program PENEPMA performs simulations of X-ray emission from samples bombarded with both electron and photon beams. It is based on the general-purpose Monte Carlo simulation package PENELOPE, an elaborate system for the simulation of coupled electron-photon transport in arbitrary materials, and on the geometry subroutine package PENGEOM, which tracks particles through complex material structures defined by quadric surfaces. After a brief description of the interaction models implemented in the simulation subroutines and of the structure and operation of PENEPMA, we provide an overview of the capabilities of the program along with several examples of its application to the modeling of electron probe microanalysis measurements...
May 15, 2017: Microscopy and Microanalysis
Marek E Schmidt, Anto Yasaka, Masashi Akabori, Hiroshi Mizuta
The recent technological advance of the gas field ion source (GFIS) and its successful integration into systems has renewed the interest in the focused ion beam (FIB) technology. Due to the atomically small source size and the use of light ions, the limitations of the liquid metal ion source are solved as device dimensions are pushed further towards the single-digit nanometer size. Helium and neon ions are the most widely used, but a large portfolio of available ion species is desirable, to allow a wide range of applications...
May 10, 2017: Microscopy and Microanalysis
Otilia Zarnescu, Ana-Maria Petrescu, Alexandra Gaspar, Oana Craciunescu
Cytological responses in different organs of sentinel organisms have proven to be useful tools for characterizing the health status of those organisms and assessing the impact of environmental contaminants. Our study shows that nickel (II) accumulated in both germ cells (oogonia and developing oocytes) and somatic cells (muscle cells, follicle cells) in the Astacus leptodactylus ovary. Muscle cells from ovarian wall show disorganization and the disruption of cytoplasmic microtubules and pyknosis of the cell nucleus...
May 10, 2017: Microscopy and Microanalysis
Joshua A Taillon, Valery Ray, Lourdes G Salamanca-Riba
This letter describes an innovative spin-coating system, built from off-the-shelf components, that can easily and inexpensively be integrated into any laboratory environment. Combined with a liquid suspension of conductive polymer, such a "rotary coater" enables simple coating of planar samples to create a physical protective barrier on the sample surface. This barrier aids in charge dissipation during scanning electron microscope and focused ion beam (FIB) imaging and provides wide-scale protection of the sample surface from ion bombardment during FIB imaging and gas-assisted deposition...
May 9, 2017: Microscopy and Microanalysis
Albe C Swanepoel, Odette Emmerson, Etheresia Pretorius
Combined oral contraceptive (COC) use is a risk factor for venous thrombosis (VT) and related to the specific type of progestin used. VT is accompanied by inflammation and pathophysiological clot formation, that includes aberrant erythrocytes and fibrin(ogen) interactions. In this paper, we aim to determine the influence of progesterone and different synthetic progestins found in COCs on the viscoelasticity of whole blood clots, as well as erythrocyte morphology and membrane ultrastructure, in an in vitro laboratory study...
May 8, 2017: Microscopy and Microanalysis
Rodolfo Mastropasqua, Luca Agnifili, Vincenzo Fasanella, Mario Nubile, Agbeanda A Gnama, Gennaro Falconio, Paolo Perri, Silvio Di Staso, Cesare Mariotti
Ocular surface diseases (OSDs) represent a widely investigated field of research given their growing incidence and the negative impact on quality of life. During OSDs, cytokines generated by damaged epithelia trigger and deregulate the lymphoid cells composing the eye-associated lymphoid tissues, inducing an immune-mediated chronic inflammation that amplifies and propagates the disease during time. The conjunctiva-associated lymphoid tissue (CALT), given its particular position that permits immune cells covering the cornea, might play a crucial role in the development of OSDs...
May 8, 2017: Microscopy and Microanalysis
Albe C Swanepoel, Odette Emmerson, Etheresia Pretorius
As erythrocyte and estrogens interact so closely and erythrocytes can indicate the healthiness of an individual, it is essential to investigate the effects of natural estrogens as well as synthetic estrogens on these cells. Whole blood samples were used for thromboelastography (TEG), light microscopy (LM), and scanning electron microscopy (SEM) investigation. Viscoelastic investigation with TEG revealed that estrogens affected the rate of clot formation without any significant effect on the strength or stability of the clot...
May 8, 2017: Microscopy and Microanalysis
Kai Bachmann, Max Frenzel, Joachim Krause, Jens Gutzmer
The identification and accurate characterization of discrete grains of rare minerals in sulfide base-metal ores is usually a cumbersome procedure due to the small grain sizes (typically <10 μm) and complex mineral assemblages in the material. In this article, a new strategy for finding and identifying indium minerals, and quantifying their composition and abundance is presented, making use of mineral liberation analysis (MLA) and electron probe microanalysis (EPMA). The method was successfully applied to polymetallic massive sulfide ores from the Neves-Corvo deposit in Portugal...
May 3, 2017: Microscopy and Microanalysis
Benedicta D Arhatari, Matthew Zonneveldt, John Thornton, Brian Abbey
Ceramic matrix composites (CMCs) are structural materials, which have useful properties that combine high strength at high temperatures with moderate toughness. Carbon fibers within a matrix of carbon and silicon carbide, called C/C-SiC, are a particular class of CMC noted for their high oxidation resistance. Here we use a combination of four-point bending and X-ray radiography, to study the mechanical failure of C/C-SiC CMCs. Correlating X-ray radiographic and load/displacement curve data reveals that the fiber bundles act to slow down crack propagation during four-point bending tests...
April 24, 2017: Microscopy and Microanalysis
János L Lábár, Partha P Das
Diffuse rings from amorphous materials sit on a steep background resulting in a monotonically decreasing intensity over scattering vector length, frequently with no clear local maximum that could be used to determine the center of the ring. The novelty of the method reported here is that it successful processes such weak patterns. It is based on separating the angular dependence of the positions of the maxima on the azimuthal angle in the measured two-dimensional pattern for a manually preselected peak. Both pattern center and elliptical distortion are simultaneously refined from this angular dependence...
April 24, 2017: Microscopy and Microanalysis
Pedro Nolasco, Ana J Dos Anjos, José Dias, Paulo V Coelho, Carla Coelho, Manuel Evaristo, Albano Cavaleiro, António Maurício, Manuel F C Pereira, Virgínia Infante, António P Alves de Matos, Raúl C Martins, Patricia A Carvalho
Lithotripsy methods show relatively low efficiency in the fragmentation of sialoliths compared with the success rates achieved in the destruction of renal calculi. However, the information available on the mechanical behavior of sialoliths is limited and their apparently tougher response is not fully understood. This work evaluates the hardness and Young's modulus of sialoliths at different scales and analyzes specific damage patterns induced in these calcified structures by ultrasonic vibrations, pneumoballistic impacts, shock waves, and laser ablation...
April 24, 2017: Microscopy and Microanalysis
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