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Microscopy and Microanalysis

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https://www.readbyqxmd.com/read/28502269/penepma-a-monte-carlo-program-for-the-simulation-of-x-ray-emission-in-electron-probe-microanalysis
#1
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
https://www.readbyqxmd.com/read/28487005/nitrogen-gas-field-ion-source-gfis-focused-ion-beam-fib-secondary-electron-imaging-a-first-look
#2
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
https://www.readbyqxmd.com/read/28486998/effect-of-sublethal-nickel-chloride-exposure-on-crayfish-astacus-leptodactylus-ovary-an-ultrastructural-autometallographic-and-electrophoretic-analyses
#3
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
https://www.readbyqxmd.com/read/28482943/teaching-an-old-material-new-tricks-easy-and-inexpensive-focused-ion-beam-fib-sample-protection-using-conductive-polymers
#4
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
https://www.readbyqxmd.com/read/28480839/effect-of-progesterone-and-synthetic-progestins-on-whole-blood-clot-formation-and-erythrocyte-structure
#5
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
https://www.readbyqxmd.com/read/28480834/the-conjunctiva-associated-lymphoid-tissue-in-chronic-ocular-surface-diseases
#6
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
https://www.readbyqxmd.com/read/28478790/the-effect-of-endogenous-and-synthetic-estrogens-on-whole-blood-clot-formation-and-erythrocyte-structure
#7
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
https://www.readbyqxmd.com/read/28464970/advanced-identification-and-quantification-of-in-bearing-minerals-by-scanning-electron-microscope-based-image-analysis
#8
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
https://www.readbyqxmd.com/read/28434434/local-structural-damage-evaluation-of-a-c-c-sic-ceramic-matrix-composite
#9
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
https://www.readbyqxmd.com/read/28434432/pattern-center-and-distortion-determined-from-faint-diffuse-electron-diffraction-rings-from-amorphous-materials
#10
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
https://www.readbyqxmd.com/read/28434428/local-response-of-sialoliths-to-lithotripsy-cues-on-fragmentation-outcome
#11
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
https://www.readbyqxmd.com/read/28416035/measuring-the-autocorrelation-function-of-nanoscale-three-dimensional-density-distribution-in-individual-cells-using-scanning-transmission-electron-microscopy-atomic-force-microscopy-and-a-new-deconvolution-algorithm
#12
Yue Li, Di Zhang, Ilker Capoglu, Karl A Hujsak, Dhwanil Damania, Lusik Cherkezyan, Eric Roth, Reiner Bleher, Jinsong S Wu, Hariharan Subramanian, Vinayak P Dravid, Vadim Backman
Essentially all biological processes are highly dependent on the nanoscale architecture of the cellular components where these processes take place. Statistical measures, such as the autocorrelation function (ACF) of the three-dimensional (3D) mass-density distribution, are widely used to characterize cellular nanostructure. However, conventional methods of reconstruction of the deterministic 3D mass-density distribution, from which these statistical measures can be calculated, have been inadequate for thick biological structures, such as whole cells, due to the conflict between the need for nanoscale resolution and its inverse relationship with thickness after conventional tomographic reconstruction...
April 18, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28399948/method-for-estimating-the-charge-density-distribution-on-a-dielectric-surface
#13
Takuya Nakashima, Hiroyuki Suhara, Hidekazu Murata, Hiroshi Shimoyama
High-quality color output from digital photocopiers and laser printers is in strong demand, motivating attempts to achieve fine dot reproducibility and stability. The resolution of a digital photocopier depends on the charge density distribution on the organic photoconductor surface; however, directly measuring the charge density distribution is impossible. In this study, we propose a new electron optical instrument that can rapidly measure the electrostatic latent image on an organic photoconductor surface, which is a dielectric surface, as well as a novel method to quantitatively estimate the charge density distribution on a dielectric surface by combining experimental data obtained from the apparatus via a computer simulation...
April 12, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28376951/measurement-error-in-atomic-scale-scanning-transmission-electron-microscopy-energy-dispersive-x-ray-spectroscopy-stem-eds-mapping-of-a-model-oxide-interface
#14
Steven R Spurgeon, Yingge Du, Scott A Chambers
With the development of affordable aberration correctors, analytical scanning transmission electron microscopy (STEM) studies of complex interfaces can now be conducted at high spatial resolution at laboratories worldwide. Energy-dispersive X-ray spectroscopy (EDS) in particular has grown in popularity, as it enables elemental mapping over a wide range of ionization energies. However, the interpretation of atomically resolved data is greatly complicated by beam-sample interactions that are often overlooked by novice users...
April 5, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28376946/stability-of-a-bifunctional-cu-based-core-zeolite-shell-catalyst-for-dimethyl-ether-synthesis-under-redox-conditions-studied-by-environmental-transmission-electron-microscopy-and-in-situ-x-ray-ptychography
#15
Sina Baier, Christian D Damsgaard, Michael Klumpp, Juliane Reinhardt, Thomas Sheppard, Zoltan Balogh, Takeshi Kasama, Federico Benzi, Jakob B Wagner, Wilhelm Schwieger, Christian G Schroer, Jan-Dierk Grunwaldt
When using bifunctional core@shell catalysts, the stability of both the shell and core-shell interface is crucial for catalytic applications. In the present study, we elucidate the stability of a CuO/ZnO/Al2O3@ZSM-5 core@shell material, used for one-stage synthesis of dimethyl ether from synthesis gas. The catalyst stability was studied in a hierarchical manner by complementary environmental transmission electron microscopy (ETEM), scanning electron microscopy (SEM) and in situ hard X-ray ptychography with a specially designed in situ cell...
April 5, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28367787/segmentation-and-quantitative-analysis-of-apoptosis-of-chinese-hamster-ovary-cells-from-fluorescence-microscopy-images
#16
Yuncheng Du, Hector M Budman, Thomas A Duever
Accurate and fast quantitative analysis of living cells from fluorescence microscopy images is useful for evaluating experimental outcomes and cell culture protocols. An algorithm is developed in this work to automatically segment and distinguish apoptotic cells from normal cells. The algorithm involves three steps consisting of two segmentation steps and a classification step. The segmentation steps are: (i) a coarse segmentation, combining a range filter with a marching square method, is used as a prefiltering step to provide the approximate positions of cells within a two-dimensional matrix used to store cells' images and the count of the number of cells for a given image; and (ii) a fine segmentation step using the Active Contours Without Edges method is applied to the boundaries of cells identified in the coarse segmentation step...
April 3, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28343460/new-methods-of-morphometric-analyses-on-scyphozoan-jellyfish-statoliths-including-the-first-direct-evidence-for-statolith-growth-using-calcein-as-a-fluorescent-marker
#17
Ilka Sötje, Tamar Dishon, Frank Hoffmann, Sabine Holst
Statoliths are the only hard structures in the gelatinous bell of most scyphozoan medusae and investigations on these structures could promote investigations of the understudied population dynamics and phylogeny of jellyfish. We examined the statoliths of Aurelia aurita jellyfish of different ages by light microscopic and microtomographic measurements supplemented by scanning electron microscopy. The morphometric analyses confirmed that statolith numbers and sizes increase during jellyfish development and revealed that newly-formed statoliths had similar shapes that may change during statolith growth...
March 27, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28337951/true-atomic-scale-imaging-in-three-dimensions-a-review-of-the-rebirth-of-field-ion-microscopy
#18
Francois Vurpillot, Frédéric Danoix, Matthieu Gilbert, Sebastian Koelling, Michal Dagan, David N Seidman
This article reviews recent advances utilizing field-ion microscopy (FIM) to extract atomic-scale three-dimensional images of materials. This capability is not new, as the first atomic-scale reconstructions of features utilizing FIM were demonstrated decades ago. The rise of atom probe tomography, and the application of this latter technique in place of FIM has unfortunately severely limited further FIM development. Currently, the ubiquitous availability of extensive computing power makes it possible to treat and reconstruct FIM data digitally and this development allows the image sequences obtained utilizing FIM to be extremely valuable for many material science and engineering applications...
March 24, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28327210/new-atom-probe-tomography-reconstruction-algorithm-for-multilayered-samples-beyond-the-hemispherical-constraint
#19
Nicolas Rolland, François Vurpillot, Sébastien Duguay, Baishakhi Mazumder, James S Speck, Didier Blavette
Accuracy of atom probe tomography measurements is strongly degraded by the presence of phases that have different evaporation fields. In particular, when there are perpendicular interfaces to the tip axis in the specimen, layers thicknesses are systematically biased and the resolution is degraded near the interfaces. Based on an analytical model of field evaporated emitter end-form, a new algorithm dedicated to the 3D reconstruction of multilayered samples was developed. Simulations of field evaporation of bilayer were performed to evaluate the effectiveness of the new algorithm...
March 22, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28322178/interface-segregation-and-nitrogen-measurement-in-fe-mn-n-steel-by-atom-probe-tomography
#20
Brian Langelier, Hugo P Van Landeghem, Gianluigi A Botton, Hatem S Zurob
Improved understanding of the interactions between solutes and the austenite/ferrite interface can benefit modeling of ferrite growth during austenite decomposition, as the transformation kinetic is significantly affected by solutes that influence interface mobility. Solute-interface interactions dominate solute segregation at the interface in binary systems, but in multi-component alloys, solute-solute interactions may also affect segregation. In this study, interface segregation in Fe-Mn-N is examined and compared with Fe-Mn-C, to reveal the extent to which C affects the segregation of Mn...
March 21, 2017: Microscopy and Microanalysis
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