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Microscopy and Microanalysis

Rebecca S Jones, Pin H Chang, Tzlil Perahia, Katrina A Harmon, Lorain Junor, Michael J Yost, Daping Fan, John F Eberth, Richard L Goodwin
Vascular stenosis, the abnormal narrowing of blood vessels, arises from defective developmental processes or atherosclerosis-related adult pathologies. Stenosis triggers a series of adaptive cellular responses that induces adverse remodeling, which can progress to partial or complete vessel occlusion with numerous fatal outcomes. Despite its severity, the cellular interactions and biophysical cues that regulate this pathological progression are poorly understood. Here, we report the design and fabrication of a three-dimensional (3D) in vitro system to model vascular stenosis so that specific cellular interactions and responses to hemodynamic stimuli can be investigated...
July 17, 2017: Microscopy and Microanalysis
Weiyang Chen, Bo Liao, Weiwei Li, Xiangjun Dong, Matthew Flavel, Markandeya Jois, Guojun Li, Bo Xian
Image segmentation is a key process in analyzing biological images. However, it is difficult to detect the differences between foreground and background when the image is unevenly illuminated. The unambiguous segmenting of multi-well plate microscopy images with various uneven illuminations is a challenging problem. Currently, no publicly available method adequately solves these various problems in bright-field multi-well plate images. Here, we propose a new method based on contrast values which removes the need for illumination correction...
July 17, 2017: Microscopy and Microanalysis
Ryan J Wu, Anudha Mittal, Michael L Odlyzko, K Andre Mkhoyan
Sub-angstrom scanning transmission electron microscopy (STEM) allows quantitative column-by-column analysis of crystalline specimens via annular dark-field images. The intensity of electrons scattered from a particular location in an atomic column depends on the intensity of the electron probe at that location. Electron beam channeling causes oscillations in the STEM probe intensity during specimen propagation, which leads to differences in the beam intensity incident at different depths. Understanding the parameters that control this complex behavior is critical for interpreting experimental STEM results...
July 4, 2017: Microscopy and Microanalysis
Andreia Machado, Sophie Wolf, Luis C Alves, Ildiko Katona-Serneels, Vincent Serneels, Stefan Trümpler, Márcia Vilarigues
The history and iconography of Swiss stained glass dating between the 16th and 18th centuries are well studied. However, the chemical and morphological characteristics of the glass and glass paints, particularly the nature of the raw materials, the provenance of the glass, and the technology used to produce it are less well understood. In this paper, we studied two sets of samples from stained-glass panels attributed to Switzerland, which date from the 16th to 17th centuries: the first set comes from Pena National Palace collection, the second from Vitrocentre Romont...
June 23, 2017: 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
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