Artykuły w czasopismach: „Electron probe microanalysis EPMA”

1

Willich, Peter, i Kirsten Schiffmann. "Electron probe microanalysis of borophosphosilicate coatings". Proceedings, annual meeting, Electron Microscopy Society of America 48, nr 2 (12.08.1990): 226–27. http://dx.doi.org/10.1017/s0424820100134739.

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Planarization and passivation of integrated circuits by use of borophosphosilicate glass (BPSG) is of considerable technological interest. BPSG is prepared by chemical vapour deposition and electron probe microanalysis (EPMA) offers the possibility of non-destructive characterization in respect of composition and film thickness. Particular difficulties of EPMA are due to the insulating character of BPSG in combination with the demand for analysis of ultra-light elements (B and O). However, EPMA of BPSG also demonstrates the accuracy of recent bulk and thin film data processing when based on refined experimental procedures.Carbon coating is required to carry out reproducible measurements on BPSG. The C-Kα intensity determined on various samples and mineral standards (Table 1) shows a wide variation of the carbon film thickness (10-40 nm), even when a set of samples was simultaneously coated. The film thickness of BPSG is in the range of 0.3-1.5 μm and consequently EPMA has to be performed at a low electron energy (Eo= 4-10 keV) to enable ‘bulk’ quantitative analysis without influence of the silicon substrate.

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Lakis, Rollin E., Charles E. Lyman i Joseph I. Goldstein. "Electron-probe microanalysis of porous materials". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 2 (sierpień 1992): 1660–61. http://dx.doi.org/10.1017/s0424820100132935.

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Conventional electron probe microanalysis (EPMA) requires solid, flat-polished specimens, and similarly prepared standards of known composition. Unfortunately, an increasing number of technologically important materials are particulate in nature and contain significant porosity. Supported heterogeneous catalysts are an important example. Many catalysts of industrial importance consist of a number of active metals and promoters dispersed in a porous (50% theoretical density, 200 m2/g surface area) ceramic support material. It is of great practical interest to determine the concentration and precise location of each component within the support material, but quantitative EPMA has typically been avoided because of the bulk porosity and surface roughness. In order to assess the effects which porosity and the accompanying surface roughness have upon quantitative EPMA, two types of model porous specimens were prepared; one an insulator (alpha alumina) and the other a conductor (silver). The alumina specimens (Figure l.)were prepared to between 57% theoretical density and full density by controlled sintering of 0.3 μm alumina powder.

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Merlet, C., X. Llovet, S. Segui, J. M. Fernández-Varea i F. Salvat. "Ionization Cross Sections for Quantitative Electron Probe Microanalysis". Microscopy and Microanalysis 7, S2 (sierpień 2001): 672–73. http://dx.doi.org/10.1017/s1431927600029433.

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Quantitative procedures in electron probe microanalysis (EPMA) require the knowledge of various atomic parameters, the most fundamental of which is the ionization cross section. A number of semi-empirical, approximate analytical formulas have been proposed to calculate the ionization cross section. The simplicity of these formulas makes them suitable for quantitative EPMA procedures. However, it is difficult to assess their reliability because of the lack of accurate experimental data. Indeed, inspection of currently available data reveals that they are still scarce for many elements and, when they are available, one usually finds significant discrepancies between data from different authors. Fortunately, the inaccuracies in the semi-empirical cross section formulas used in EPMA have only a small effect on the analytical results when standards are used. Nonetheless, in quantitative EPMA studies at low overvoltages or using standardless methods, the evaluated compositions largely depend on the adopted ionization cross sections and, therefore, knowledge of accurate ionization cross sections is a requisite for the development of improved quantification methods.

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Goresh, S. "Industrial Applications of Electron Probe Microanalysis (EPMA)". Microscopy and Microanalysis 17, S2 (lipiec 2011): 616–17. http://dx.doi.org/10.1017/s1431927611003953.

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Somlyo, A. P., i Avril V. Somlyo. "Electron Probe Analysis and Cell Physiology". Proceedings, annual meeting, Electron Microscopy Society of America 43 (sierpień 1985): 2–5. http://dx.doi.org/10.1017/s0424820100117169.

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Electron probe x-ray microanalysis (EPMA) of rapidly frozen tissues is a uniquely powerful method for dealing with a large class of general problems in cell physiology, as it is suitable for measuring, under direct vision, the elemental composition of cells and cell organelles. EPMA can reach a spatial resolution of at least 10nm, and its practically attainable sensitivity (for Ca) is 0.3mmol Ca/kg dry wt. Therefore, the composition of mitochondria and of other organelles, as small as the endoplasmic reticulum (ER), can be quantitated with EPMA. The most extensive applications of EPMA to cell physiology have been in muscle physiology and epithelial transport (for reviews). In this discussion, we will illustrate the applications of EPMA by summarizing studies from our laboratory on striated and smooth muscle function. We shall also illustrate the use of EPMA to study the effects of drugs on organelles. The general applicability of EPMA to cell transport will be illustrated, somewhat arbitrarily, through EPMA studies of vertebrate photoreceptors. We are convinced that as experience is gained, largely with the specimen preparatory techniques required, EPMA will also find increasing applications to cell pathology, as illustrated by the recent demonstration of calcium compartmentalization in sickle red blood cells.

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Matthews, Mike B., Ben Buse i Stuart L. Kearns. "Electron Probe Microanalysis Through Coated Oxidized Surfaces". Microscopy and Microanalysis 25, nr 05 (16.07.2019): 1112–29. http://dx.doi.org/10.1017/s1431927619014715.

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AbstractLow voltage electron probe microanalysis (EPMA) of metals can be complicated by the presence of a surface oxide. If a conductive coating is applied, analysis becomes one of a three-layer structure. A method is presented which allows for the coating and oxide thicknesses and the substrate intensities to be determined. By restricting the range of coating and oxide thicknesses, tc and to respectively, x-ray intensities can be parameterized using a combination of linear functions of tc and to. tc can be determined from the coating element k-ratio independently of the oxide thickness. to can then be derived from the O k-ratio and tc. From tc and to the intensity components of the k-ratios from the oxide layer and substrate can each be derived. Modeled results are presented for an Ag on Bi2O3 on Bi system, with tc and to each ranging from 5 to 20 nm, for voltages of 5–20 kV. The method is tested against experimental measurements of Ag- or C-coated samples of polished Bi samples which have been allowed to naturally oxidize. Oxide thicknesses determined both before and after coating with Ag or C are consistent. Predicted Bi Mα k-ratios also show good agreement with EPMA-measured values.

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Ro, Chul-Un. "Quantitative energy-dispersive electron probe X-ray microanalysis of individual particles". Powder Diffraction 21, nr 2 (czerwiec 2006): 140–44. http://dx.doi.org/10.1154/1.2204068.

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An electron probe X-ray microanalysis (EPMA) technique using an energy-dispersive X-ray detector with an ultrathin window, designated low-Z particle EPM, has been developed. The low-Z particle EPMA allows the quantitative determination of concentrations of low-Z elements, such as C, N, and O, as well as higher-Z elements that can be analyzed by conventional energy-dispersive EPMA. The quantitative determination of low-Z elements (using full Monte Carlo simulations, from the electron impact to the X-ray detection) in individual environmental particles has improved the applicability of single-particle analysis, especially in atmospheric environmental aerosol research; many environmentally important atmospheric particles, e.g. sulfates, nitrates, ammonium, and carbonaceous particles, contain low-Z elements. The low-Z particle EPMA was applied to characterize loess soil particle samples of which the chemical compositions are well defined by the use of various bulk analytical methods. Chemical compositions of the loess samples obtained from the low-Z particle EPMA turn out to be close to those from bulk analyses. In addition, it is demonstrated that the technique can also be used to assess the heterogeneity of individual particles.

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Somlyo, Avril V., i Andrew P. Somlyo. "Electron probe x-ray microanalysis of subcellular ion transport in situ". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 1 (sierpień 1992): 16–17. http://dx.doi.org/10.1017/s0424820100120485.

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Electron probe x ray microanalysis [EPMA] provides quantitative information within a single spectrum about elements of biological interest with atomic number of 11 or greater. Therefore, the transport of ions and their accompanying co and counter ions across organelle membranes can be studied in situ by sampling within and adjacent to the intracellular organelle of interest under resting and stimulated conditions.EPMA is based on the fact that the ionization of atoms by fast electrons generates x rays having energies characteristic of the excited atoms. The interaction of incident fast electrons with atomic nuclei generates a background of continuum x rays. Elemental quantitation of ultra thin sections with EPMA is generally based on the linear relationship between elemental concentrations and the ratio of the number of characteristic/continuum. The use of this principle, together with the appropriate standards for calibration, has been the most successful approach for quantitative biological EPMA. The spatial resolution of EPMA at present is better than 10 nm and the practical limit of sensitivity for detecting calcium, (albeit with high electron dose), is approximately 0.3 mmol/kg dry wt. Two modes of data collection are utilized: fixed probe analysis of a region of interest or a scanning probe mode, where an x ray spectrum is collected at each picture point, to obtain quantitative elemental x ray maps. To preserve the morphology and the in vivo distribution of diffusible elements, we prepare specimens by rapid freezing in sub cooled Freon or, more recently with a Lifecell CF100 metal are mirror device; thin sections cut at -130 °C to -160 °C on a Reichert cryoultramicrotome. Msec time resolution of physiological are events can be achieved by freeze trapping.

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Takahashi, Hideyuki, Toshiaki Suzuki i Charles Nielsen. "Application Ofthinfilm Method to Electronic Probe Microanalysis (EPMA)". Microscopy and Microanalysis 7, S2 (sierpień 2001): 686–87. http://dx.doi.org/10.1017/s1431927600029500.

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Usually, in electron probe microanalysis, the X-ray diffusion range is around lμm on the sample surface. For this reason, the maximum useful magnification of X-ray image seems to be limited to a few thousand times. The X-ray diffusion on the \im order takes place in the bulk sample. However, when a sample is cut to a thin film, it is likely that the X-ray diffusion range will be made smaller, and it is also possible to observe very a narrow area X-ray image at higher magnification. The thin film method is a sampling technique used often in transmission electron microscopy. The microtome method has been applied to organic materials, and the method using focus ion beam (FIB) has been applied to inorganic materials. Takahashi et al. have reported the effectiveness of the microtome application to EPMA of soft materials. in this report, the FIB method was applied to a sampling of inorganic materials in order to obtain high resolution X-ray images of real samples.

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Robertson, Vernon. "What Are the Advantages of a FE-EPMA or FE-SEM (Even When Not Analyzing Submicron Features at Low kV and High Beam Current)?" Microscopy Today 31, nr 6 (listopad 2023): 10–16. http://dx.doi.org/10.1093/mictod/qaad080.

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Abstract Field emission electron probe microanalyzers (EPMA) and scanning electron microscopes (SEM) have improved in both the hardware and software. They have become workhorse instruments for imaging secondary (SE) and backscattered (BSE) electrons. Recent advancements in technology provide qualitative quantitative analysis and X-ray maps at lower kVs and higher beam current without significantly enlarging the beam diameter. On EPMAs and SEMs with W and LaB6 electron guns, spatial resolution for microanalysis was ∼1 micron. Now, with field emission (FE) guns, resolution of 300 nm for quantitative analysis and mapping of elements well below 100 nm are possible. Software has also become more user-friendly and has advanced automation algorithms that allow the “non-expert” EPMA user to collect data. However, the best part of automation sits in the user’s chair. The new EPMAs and SEMs can collect very good data, but if they don’t answer the question that is being asked, they have no use.

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Tan, Shuhui, Rencheng Li, Richard S. Vachula, Xinyue Tao, Mengdan Wen, Yizhi Liu, Haiyan Dong i Lintong Zhou. "Electron probe microanalysis of the elemental composition of phytoliths from woody bamboo species". PLOS ONE 17, nr 7 (5.07.2022): e0270842. http://dx.doi.org/10.1371/journal.pone.0270842.

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Electron probe microanalysis (EPMA) is promising for accurately determining elemental components in micro-areas of individual phytolith particles, interpreting compositional features and formation mechanisms of phytoliths in plants, identifying archeological and sedimental phytolith. However, the EPMA method of analyzing mounted slide phytoliths has not well been defined. In this study, we attempted different EPMA methods to determine the elemental compositions of phytoliths in mounted slides. Direct analysis of carbon (DAC) with other elements in phytolith could obtain abnormally high total values and carbon values. The method of carbon excluded in measuring elements (non-carbon analysis (NCA)) was feasible to obtain elemental compositions in phytolith. The NCA method was conducive to obtain the factual elemental compositions of an individual phytolith (morphotype) when the carbon content of phytolith was relatively low. The EPMA results of phytoliths from 20 bamboo species (three genera) showed that phytolith was dominantly composed of SiO2 but also included low contents of diverse other elements. The EPMA of phytoliths can provide the elemental composition of micro-areas of an individual phytolith particle. The elemental compositions of phytolith varied with their morphotypes, the genera and ecotype of bamboos. The EPMA of elemental compositions in phytoliths is a potential tool to study the formation mechanism of phytoliths, plant taxonomical identification, archaeological and paleoenvironmental reconstruction.

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Rinaldi, Romano, i Xavier Llovet. "Electron Probe Microanalysis: A Review of the Past, Present, and Future". Microscopy and Microanalysis 21, nr 5 (12.05.2015): 1053–69. http://dx.doi.org/10.1017/s1431927615000409.

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AbstractThe 50th anniversary of the application of electron probe microanalysis (EPMA) to the Earth Sciences provides an opportunity for an assessment of the state-of-the-art of the technique. Stemming from the introduction of the first automated instruments, the latest developments of EPMA and some typical applications are reviewed with an eye to the future. The most noticeable recent technical achievements such as the field-emission electron gun, the latest generation of energy and wavelength dispersive spectrometers, and the development of analytical methods based on new sets of first principle data obtained by the use of sophisticated computer codes, allow for the extension of the method to the analysis of trace elements, ultra-light elements (down to Li), small particles, and thin films, with a high degree of accuracy and precision and within a considerably reduced volume of interaction. A number of working examples and a thorough list of references provide the reader with a working knowledge of the capabilities and limitations of EPMA today.

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Salvat, F., L. Sorbier, X. Llovet i E. Acosta. "X-Ray Microanalysis with Penelope". Microscopy and Microanalysis 7, S2 (sierpień 2001): 688–89. http://dx.doi.org/10.1017/s1431927600029512.

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Monte Carlo simulation is a suitable tool for the numerical generation of x-ray spectra by electron beams and, more specifically, for the quantification in electron probe microanalysis (EPMA). in this communication we describe the application of the general-purpose code PENELOPE to EPMA. This code simulates electron-photon showers in complex material structures consisting of homogeneous regions of arbitrary composition limited by quadric surfaces. It is devised to cover a wide energy range (from ∼500 eV to about 1 GeV). The interaction models implemented in PENELOPE are based on the most reliable information available. They combine results from first principles calculations (this is the case, e.g., for electron elastic scattering, photon Compton scattering), semiempirical models (in electron inelastic scattering) and information from evaluated data bases. to facilitate the random sampling, the cross sections of various interaction mechanisms are described through analytical expressions, which are adjusted to yield accurate values of relevant transport properties (mass attenuation coefficients, transport mean free paths, stopping powers, . . . ).

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Rehbach, Werner P., i Peter Karduck. "Quantitative electron probe microanalysis of high-Tc superconducting materials". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 2 (sierpień 1992): 1768–69. http://dx.doi.org/10.1017/s0424820100133473.

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Since the discovery of ceramics with superconducting properties at rather high temperatures by Bednorz and Müller great effort has been made to find new super conducting materials and to optimize them. To achieve good superconducting properties single-phase compounds with well defined stoichiometry especially with regard to the oxygen content are needed. For the determination of these material properties several macroscopical or microscopical techniques are applied; one of these is the electron probe microanalysis (EPMA). However, most of the work by EPMA reported so far is restricted to the determination of the metal elements in the compound. Thus such analyses are somewhat incomplete and inadequate since the major information about the oxygen is lacking. On the other hand the microprobe is so far the only microanalytical technique to quantify oxide compositions with adequate accuracy as could be demonstrated recently by several authors. It is the intention of this presentation to assess the capability as well as the the limits of this technique in fully analysing the composition and the compositional microstructure of cuprate superconductors.

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Claus, Tamme, Jonas Bünger i Manuel Torrilhon. "A Novel Reconstruction Method to Increase Spatial Resolution in Electron Probe Microanalysis". Mathematical and Computational Applications 26, nr 3 (14.07.2021): 51. http://dx.doi.org/10.3390/mca26030051.

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The spatial resolution of electron probe microanalysis (EPMA), a non-destructive method to determine the chemical composition of materials, is currently restricted to a pixel size larger than the volume of interaction between beam electrons and the material, as a result of limitations on the underlying k-ratio model. Using more sophisticated models to predict k-ratios while solving the inverse problem of reconstruction offers a possibility to increase the spatial resolution. Here, a k-ratio model based on the deterministic M1-model in Boltzmann Continuous Slowing-Down approximation (BCSD) will be utilized to present a reconstruction method for EPMA which is implemented as a PDE-constrained optimization problem. Iterative gradient-based optimization techniques are used in combination with the adjoint state method to calculate the gradient in order to solve the optimization problem efficiently. The accuracy of the spatial resolution still depends on the number and quality of the measured data, but in contrast to conventional reconstruction methods, an overlapping of the interaction volumes of different measurements is permissible without ambiguous solutions. The combination of k-ratios measured with various electron beam configurations is necessary for a high resolution. Attempts to reconstruct materials with synthetic data show challenges that occur with small reconstruction pixels, but also indicate the potential to improve the spatial resolution in EPMA using the presented method.

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McGee, James J. "Progress in Electron-Probe Microanalysis of Boron in Geologic Samples". Proceedings, annual meeting, Electron Microscopy Society of America 54 (11.08.1996): 696–97. http://dx.doi.org/10.1017/s042482010016594x.

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Despite the availability of modern instrumentation with improved detection and correction systems, the analysis of boron in geologic samples by electron probe microanalysis (EPMA) is often avoided. Many studies resort to using calculated or assumed concentrations of B based upon mineral stoichiometry rather than attempt to quantify the B contents by measurement. Assuming stoichiometric behavior for B is not always valid and disregards the possibility of variations in B content of minerals. Such assumptions can contribute to misleading crystal chemical substitution models for the other mineral constituents.With modem EPMA instrumentation, analysis of B in minerals where B is present in major concentration levels (such as in tourmaline) is possible and should be incorporated into routine analytical procedures by the mineralogical community. The effort to make B measurement routine will reinforce itself, as techniques, standards, and problems are addressed by the geologic community interested in refining the measurement application. Progress in this effort, and some of the factors in need of further consideration are discussed here.

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Somlyo, Andrew P. "The Impact of Biological Microanalysis on Analytical Electron Microscopy". Microscopy and Microanalysis 4, S2 (lipiec 1998): 170–71. http://dx.doi.org/10.1017/s1431927600020973.

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Advances in energy-dispersive detector technology were largely responsible for electron probe microanalysis (EPMA) becoming a valuable tool for biologists, while development of EPMA received much impetus from the special needs of biological research. Solid-state energy-dispersive detectors placed in close proximity to specimens in transmission electron microscopes (TEMs) provided the necessary geometric detection efficiency, hence sensitivity and higher spatial resolution, and the reasonably good energy resolution of these detectors permitted reliable separation of overlapping peaks, such as the Kα peak of the biologically important messenger, calcium, and the Kβ peak of another, biologically much more abundant element, potassium. Improvements in the pole-piece design of TEMs to allow closer access of the X-ray detector to the specimen and interfacing the software of one company with detectors provided by another also helped progress, and EPMA, in conjunction with rapid freezing of cells, was ready to address important biological problems, such as the dynamics of the composition of intracellular organelles in situ.

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Tsuji, K., Y. Murakami, K. Wagatsuma i G. Love. "Surface studies by grazing-exit electron probe microanalysis (GE-EPMA)". X-Ray Spectrometry 30, nr 2 (2001): 123–26. http://dx.doi.org/10.1002/xrs.480.

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Karduck, Peter, i Norbert Ammann. "ϕ(ρz)-Determination for Advanced Applications of Electron Probe Microanalysis". Proceedings, annual meeting, Electron Microscopy Society of America 48, nr 2 (12.08.1990): 14–15. http://dx.doi.org/10.1017/s0424820100133667.

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In the last 35 years electron probe microanalysis (EPMA) has developed to a versatile technique for the quantitative analysis of materials on a microscopic scale. This development has been initiated by the pioneering work of Castaing in 1951 (1). Already in 1955 Castaing and Descamps have introduced a basic formulation for the absorption correction to quantify characteristic x-ray data (2). This correction already presumed the knowledge of the distribution ϕ(ρz) of the generated x-ray intensity as a function of the depth ρz inside the target. The authors presented the first experimental procedure to determine this distribution for pure elements by the so called sandwich sample technique. The results of this early work, obtained for several pure elements, became a standard in the field and many authors have examined their theoretical approaches or their Monte-Carlo simulations of ϕ(ρz) by means of these ϕ(ρz) data. In the following time further attempts of ϕ(ρz) determinations by experiments or by theoretical approaches, e.g. Philibert (3), became necessary because a general application of a matrix correction to the whole elemental range, detectable by EPMA, required a generalized analytical description of ϕ(ρz).

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Lakis, R. E., E. P. Vicenzi i F. M. Allen. "Electron probe microanalysis of alumina-supported platinum catalysts". Proceedings, annual meeting, Electron Microscopy Society of America 54 (11.08.1996): 512–13. http://dx.doi.org/10.1017/s0424820100165021.

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Conventional Electron-Probe Microanalysis (EPMA) requires fully dense, flat polished specimens, and similarly prepared standards of known composition. Most supported catalyst systems do not fit the above criterion, because porosity and large internal surface areas are intrinsic qualities of useful catalyst materials. Many catalysts of commercial importance contain a number of active metals and promoters that are impregnated into porous ceramic support with well controlled concentration profiles relative to the other constituents. It would be of great practical importance to reliably measure the distribution of active materials in a quantitative manner. A previous investigation which focused upon porous alumina, identified a deficit of detected electrons which increased with increasing porosity, and was perhaps due to the roughness of the porous materials surface. This leads to unrealistically low composition totals when traditional correction procedures are employed. This study is a first step towards the collection of high statistical quality data on catalyst materials so that new matrix correction procedures may be developed for these systems.

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Lamontagne, Jérôme, Thierry Blay i Ingrid Roure. "Microbeam Analysis of Irradiated Materials: Practical Aspects". Microscopy and Microanalysis 13, nr 3 (9.05.2007): 150–55. http://dx.doi.org/10.1017/s143192760707033x.

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Among the microanalytical techniques, electron probe microanalysis (EPMA) is one of the most powerful. Its performances can be used to provide an accurate characterization. In the present article the differences between the EPMA of highly irradiated materials and standard EPMA are highlighted. It focuses on the shielded EPMA specificities. Then, the article presents the difficulties encountered during the sample preparation and the analysis (mainly due to the radioactive background). In spite of these difficulties, some valuable results can be provided by a shielded EPMA on the in-pile behavior of nuclear irradiated fuel. Some results of specific examples analyzed by EPMA in nuclear fuel research are presented.

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Goldstein, J. I. "Scanning Electron Microscopy And Electron Probe Microanalysis Of Extraterrestrial Materials". Microscopy and Microanalysis 5, S2 (sierpień 1999): 2–3. http://dx.doi.org/10.1017/s1431927600013337.

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One of the first samples analyzed by Castaing in his electron probe microanalyzer (EPMA) some 50 years ago was an iron meteorite. The Widmanstatten pattern microstructure of iron meteorites can be observed at very low magnifications ( Fig. 1). These meteorites are ideal samples for microanalysis because of the Ni gradient which extends over 10 to 1000 microns in the parent taenite phase of these Fe-Ni samples (Fig. 3). The Ni gradient is the result of very slow cooling of the iron meteorite, in terms of millions of years, within a parent'asteroid.The scanning electron microscope (SEM) has been used to characterize the microstructure of meteorites, as well as samples from the moon and mars. For example, the microstructure of the dark etching taenite areas (T in Fig. 1) of the Carleton iron meteorite is shown in Fig 2. In this example, precipitates are observed along original martensite laths which form during the cooling of the iron meteorite at low temperatures.

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Merlet, C., X. Llovet i F. Salvat. "Measurement And Simulation Of X-Ray Emission From Multilayered Structures In Electron Probe Microanalysis." Microscopy and Microanalysis 5, S2 (sierpień 1999): 78–79. http://dx.doi.org/10.1017/s1431927600013714.

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Studies of x-ray emission from thin films on substrates using an electron probe microanalyzer (EPMA) provide useful information on the characteristics of x-ray generation by electron beams. In this study, EPMA measurements of multilayered samples were performed in order to test and improve analytical and numerical models used for quantitative EPMA. These models provide relatively accurate results for samples consisting of layers with similar average atomic numbers, because of their similar properties regarding electron transport and x-ray generation. On the contrary, these models find difficulties to describe the process when the various layers have very different atomic numbers. In a previous work, we studied the surface ionization of thin copper films of various thicknesses deposited on substrates with very different atomic numbers. In the present communication, the study is extended to the case of multilayered specimens.The studied specimens consisted of thin copper films deposited on a carbon layer which, in turn, was placed on a variety of single-element substrates, ranging from Be to Bi.

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Conty, Claude. "Today’s and Tomorrow’s Instruments". Microscopy and Microanalysis 7, nr 2 (marzec 2001): 142–49. http://dx.doi.org/10.1007/s100050010077.

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Abstract This article will discuss the importance of Raimond Castaing’s thesis on the genesis of a nondestructive and truly quantitative microanalytical method that assisted the scientific community in moving forward in the development of microanalytical instruments. I will also share with you my recollection of the decades of improvement in the electron probe microanalyzer (EPMA), that has allowed us to reach our present level of instrument sophistication, and I will explore with you my thoughts on the future evolution of this technique. To conclude, I will present the current status of related microanalysis techniques developed under Castaing in Orsay in the 1960s, as Castaing’s interest in microanalysis was not limited to electron probe microanalysis alone.

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Kubo, Yugo, i Koji Kuramochi. "Observation of Fine Distribution of Minor Dopants in an Erbium-Doped Fiber Core using a Sample Thinning Technique for Field Emission Electron Probe Microanalysis". Microscopy and Microanalysis 21, nr 6 (17.11.2015): 1398–405. http://dx.doi.org/10.1017/s1431927615015445.

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AbstractTo observe the fine distribution of minor aluminum and germanium dopants in the erbium-doped fiber (EDF) core of an optical amplifier, a sample thinning technique was applied for field emission electron probe microanalysis (FE-EPMA) together with wavelength-dispersive X-ray spectrometry. This technique significantly improved the spatial resolution without much degradation of the minimum detection limit for FE-EPMA. As such, this enabled us to observe the distribution of minor dopants in EDF. Moreover, we propose a very simple sample preparation to prevent electron-beam radiation damage, a problem involved with FE-EPMA of low-conductivity materials such as SiO2 glass, which is the main component of EDF.

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Buse, Ben, i Stuart Kearns. "Quantification of Olivine Using Fe Lα in Electron Probe Microanalysis (EPMA)". Microscopy and Microanalysis 24, nr 1 (luty 2018): 1–7. http://dx.doi.org/10.1017/s1431927618000041.

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AbstractQuantification of first series transition metal Lα X-rays is hampered by absorption and in some cases transition probabilities (fluorescence yields) varying with chemical bonding. Compound mass absorption coefficients for Fe Lα were measured in the olivine solid solution series [Forsterite (Mg2SiO4) to Fayalite (Fe2SiO4)] and the mass absorption coefficients for Fe Lα absorbed by Fe were calculated. The mass absorption coefficients vary systematically between Fo83 and Fo0. Using the measured mass absorption coefficients for both standard and unknown and by correcting for a systematic discrepancy, consistent with varying partial fluorescence yields, a good agreement between calculated k-ratios and measured k-ratios is achieved. The systematic variations allow quantification of unknown k-ratios. The described method of quantification requires modification of matrix correction routines to allow standards and unknowns to have different mass absorption coefficients, and to incorporate solid solution mass absorption coefficients and partial fluorescence yield corrections derived from regression of experimental data.

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Grover, V., P. Sengupta, K. Bhanumurthy i A. K. Tyagi. "Electron probe microanalysis (EPMA) investigations in the CeO2–ThO2–ZrO2 system". Journal of Nuclear Materials 350, nr 2 (kwiecień 2006): 169–72. http://dx.doi.org/10.1016/j.jnucmat.2006.01.001.

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Harries, Dennis. "Homogeneity testing of microanalytical reference materials by electron probe microanalysis (EPMA)". Geochemistry 74, nr 3 (październik 2014): 375–84. http://dx.doi.org/10.1016/j.chemer.2014.01.001.

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Williams, D. B. "The Impact of EDS In Materials Science Microanalysis". Microscopy and Microanalysis 4, S2 (lipiec 1998): 168–69. http://dx.doi.org/10.1017/s1431927600020961.

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Since its invention in 1968, the EDS has played an essential role in X-ray analysis of materials, at the micrometer level, in the electron probe microanalyzer (EPMA). In the EPMA, the characteristic X-ray intensity from bulk specimens is sufficient that, despite its very small collection angle, the wavelength dispersive spectrometer (WDS) can also be used. Given the excellent energy resolution of the WDS it has often been the spectrometer of choice for bulk quantitative X-ray microanalysis. Therefore, the most important role of the EDS has been in X-ray microanalysis of thin specimens in the analytical electron microscope (AEM) because, in an AEM, the limited confines of the stage mean that EDS is the only viable spectrometer. Since the pioneering work of Cliff and Lorimer in the 1970s, EDS has been the method by which all high spatial resolution X-ray microanalysis of thin foils has been performed.

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Walters, Jesse B. "MinPlot: A mineral formula recalculation and plotting program for electron probe microanalysis". Mineralogia 53, nr 1 (1.01.2022): 51–66. http://dx.doi.org/10.2478/mipo-2022-0005.

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Abstract MinPlot is a MATLAB®-based mineral formula recalculation and compositional plotting program for electron microprobe analyses (EPMA). The program offers recalculation and structural formula assignment for 15 different mineral groups: Garnet, pyroxene, olivine, amphibole, feldspar, mica, staurolite, cordierite, chlorite, chloritoid, talc, epidote, titanite, spinel, and sulfides. MinPlot is a fast and easy to use command line program and requires no prior computer programming knowledge. Percent mass fractions of oxides are loaded from datafiles and the user answers simple prompts to select mineral type, normalization scheme, and plotting options. Recalculated mineral formulas are automatically saved as output files and plots may be further manually customized by the user prior to saving. MinPlot can perform thousands of calculations in seconds and the modular nature of the program makes it simple to add new calculation routines in future releases. Combined, these features make MinPlot a powerful and useful program for the processing of EPMA data.

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Cheng, Lining, Chao Zhang, Xiaoyan Li, Renat R. Almeev, Xiaosong Yang i Francois Holtz. "Improvement of Electron Probe Microanalysis of Boron Concentration in Silicate Glasses". Microscopy and Microanalysis 25, nr 4 (18.06.2019): 874–82. http://dx.doi.org/10.1017/s1431927619014612.

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AbstractThe determination of low boron concentrations in silicate glasses by electron probe microanalysis (EPMA) remains a significant challenge. The internal interferences from the diffraction crystal, i.e. the Mo-B4C large d-spacing layered synthetic microstructure crystal, can be thoroughly diminished by using an optimized differential mode of pulse height analysis (PHA). Although potential high-order spectral interferences from Ca, Fe, and Mn on the BKα peak can be significantly reduced by using an optimized differential mode of PHA, a quantitative calibration of the interferences is required to obtain accurate boron concentrations in silicate glasses that contain these elements. Furthermore, the first-order spectral interference from ClL-lines is so strong that they hinder reliable EPMA of boron concentrations in Cl-bearing silicate glasses. Our tests also indicate that, due to the strongly curved background shape on the high-energy side of BKα, an exponential regression is better than linear regression for estimating the on-peak background intensity based on measured off-peak background intensities. We propose that an optimal analytical setting for low boron concentrations in silicate glasses (≥0.2 wt% B2O3) would best involve a proper boron-rich glass standard, a low accelerating voltage, a high beam current, a large beam size, and a differential mode of PHA.

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Bünger, Jonas, Silvia Richter i Manuel Torrilhon. "A Model for Characteristic X-Ray Emission in Electron Probe Microanalysis Based on the (Filtered) Spherical Harmonic () Method for Electron Transport". Microscopy and Microanalysis 28, nr 2 (kwiecień 2022): 454–68. http://dx.doi.org/10.1017/s1431927622000083.

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Classical $k$-ratio models, for example, ZAF and $\phi ( \rho z)$, used in electron probe microanalysis (EPMA) assume a homogeneous or multilayered material structure, which essentially limits the spatial resolution of EPMA to the size of the interaction volume where characteristic X-rays are produced. We present a new model for characteristic X-ray emission that avoids assumptions on the material structure to not restrict the resolution of EPMA a priori. Our model bases on the spherical harmonic ($P_{\rm N}$) approximation of the Boltzmann equation for electron transport in continuous slowing down approximation. $P_{\rm N}$ models have a simple structure, are hierarchical in accuracy and well-suited for efficient adjoint-based gradient computation, which makes our model a promising alternative to classical models in terms of improving the resolution of EPMA in the future. We present results of various test cases including a comparison of the $P_{\rm N}$ model to a minimum entropy moment model as well as Monte-Carlo (MC) trajectory sampling, a comparison of $P_{\rm N}$-based $k$-ratios to $k$-ratios obtained with MC, a comparison with experimental data of electron backscattering yields as well as a comparison of $P_{\rm N}$ and MC based on characteristic X-ray generation in a three-dimensional material probe with fine structures.

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Ngo, H., J. Ruben, J. Arends, D. White, G. J. Mount, M. C. R. B. Peters, R. V. Faller i A. Pfarrer. "Electron Probe Microanalysis and Transverse Microradiography Studies of Artificial Lesions in Enamel and Dentin: A Comparative Study". Advances in Dental Research 11, nr 4 (listopad 1997): 426–32. http://dx.doi.org/10.1177/08959374970110040801.

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In cariology and research involving the interactions between restorative materials and dental hard tissues, it is important for small changes in tooth mineral content to be measurable. Currently, transverse microradiography (TMR) is the most accepted tool for the above purpose. Electron Probe Microanalysis (EPMA) can yield both qualitative identification of elements and quantitative compositional information. The purpose of this study was to compare the mineral distribution in well-defined artificial lesions, in dentin and enamel, by the use of both TMR and EPMA on the same sample. The good correlation between the two sets of data validates EPMA as a technique and helps in the interpretation of its results. The data from TMR analysis are expressed as vol% of mineral, while EPMA gives the levels of Ca and phosphate in wt%. The conversion between the two sets of data is complicated by the fact that local density is, as yet, unknown.

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Cochrane, Nathan J., Youichi Iijima, Peiyan Shen, Yi Yuan, Glenn D. Walker, Coralie Reynolds, Colin M. MacRae, Nicholas C. Wilson, Geoffrey G. Adams i Eric C. Reynolds. "Comparative Study of the Measurement of Enamel Demineralization and Remineralization Using Transverse Microradiography and Electron Probe Microanalysis". Microscopy and Microanalysis 20, nr 3 (24.04.2014): 937–45. http://dx.doi.org/10.1017/s1431927614000622.

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AbstractTransverse microradiography (TMR) and electron probe microanalysis (EPMA) are commonly used for characterizing dental tissues. TMR utilizes an approximately monochromatic X-ray beam to determine the mass attenuation of the sample, which is converted to volume percent mineral (vol%min). An EPMA stimulates the emission of characteristic X-rays from a variable volume of sample (dependent on density) to provide compositional information. The aim of this study was to compare the assessment of sound, demineralized, and remineralized enamel using both techniques. Human enamel samples were demineralized and a part of each was subsequently remineralized. The same line profile through each demineralized lesion was analyzed using TMR and EPMA to determine vol%min and wt% elemental composition and atomic concentration ratio information, respectively. The vol%min and wt% values determined by each technique were significantly correlated but the absolute values were not similar. This was attributable to the complex ultrastructural composition, the variable density of the samples analyzed, and the nonlinear interaction of the EPMA-generated X-rays. EPMA remains an important technique for obtaining atomic ratio information, but its limitations in determining absolute mineral content indicate that it should not be used in place of TMR for determining the mineral density of dental hard tissues.

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Schomisch Moravec, Christine, i Meredith Bond. "Subcellular Calcium (Ca2+) Redistribution During Cardiac Muscle Contraction by Electron Probe Microanalysis (EPMA)". Proceedings, annual meeting, Electron Microscopy Society of America 48, nr 2 (12.08.1990): 136–37. http://dx.doi.org/10.1017/s0424820100134272.

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Substantial evidence suggests that the increase in cytosolic Ca2+ which occurs upon stimulation of cardiac muscle originates from the sarcoplasmic reticulum (SR) and that its release is triggered by a transient rise in cytosolic Ca2+. The junctional SR has been proposed as a Ca2+ release site, based on a number of observations, e.g. measurements by EPMA have demonstrated significant Ca2+ stores in the junctional SR in resting cardiac muscle; the ryanodine-sensitive Ca2+ release channels are associated with junctional SR membrane and the low affinity Ca2+ binding protein, calsequestrin, is localized to the junctional SR. Although considerable evidence implicates the junctional SR as an intracellular Ca2+ store in cardiac muscle, release of Ca2+ from the junctional SR, upon muscle stimulation, has not been directly demonstrated. We therefore propose to use EPMA to directly measure the Ca2+ content of junctional SR in both relaxed and contracted cardiac muscle to determine whether Ca2+ is released from the junctional SR during contraction.

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Nihtianova, D. D., I. T. Ivanov, J. J. Macicek i I. K. Georgieva. "Crystallographic data for BaMnSiO4: A new phase in the system BaO-MnO-SiO2". Powder Diffraction 12, nr 3 (wrzesień 1997): 167–70. http://dx.doi.org/10.1017/s0885715600009659.

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A new phase in the system BaO-MnO-SiO2 obtained by a pyrosynthetic method has been investigated using selected area electron diffraction (SAED), electron probe microanalysis (EPMA), and X-ray powder diffraction. The lattice parameters and a possible space group of the phase with a general composition BaMnSiO4 were determined as follows: a=5.370(2), b=18.447(7), c=8.498(5) Å, Z=8, Space Group Pmc21.

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Chong, Saehwa, Jared O. Kroll, Jarrod V. Crum i Brian J. Riley. "Synthesis and crystal structure of a neodymium borosilicate, Nd3BSi2O10". Acta Crystallographica Section E Crystallographic Communications 75, nr 5 (25.04.2019): 700–702. http://dx.doi.org/10.1107/s2056989019005024.

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A lanthanide borosilicate, trineodymium borosilicate or Nd3BSi2O10, was synthesized using a flux method with LiCl, and its structure was determined from X-ray powder diffraction (XRD) and electron probe microanalysis (EPMA). The structure is composed of layers with [SiO4]4− and [BSiO6]5− anions alternating along the c axis linked by Nd3+ cations between them.

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Schulz, Bernhard, Joachim Krause i Wolfgang Dörr. "A Protocol for Electron Probe Microanalysis (EPMA) of Monazite for Chemical Th-U-Pb Age Dating". Minerals 14, nr 8 (12.08.2024): 817. http://dx.doi.org/10.3390/min14080817.

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A protocol for the monazite (LREE,Y,Th,U,Si,Ca)PO4 in situ Th-U-Pb dating by electron probe microanalyser (EPMA) involves a suitable reference monazite. Ages of several potential reference monazites were determined by TIMS-U-Pb isotope analysis. The EPMA protocol is based on calibration with REE-orthophosphates and a homogeneous Th-rich reference monazite at beam conditions of 20 kV, 50 nA, and 5 µm for best possible matrix matches and avoidance of dead time bias. EPMA measurement of samples and repeated analysis of the reference monazite are performed at beam conditions of 20 kV, 100 nA, and 5 µm. Analysis of Pb and U on a PETL crystal requires YLg-on-PbMa and ThMz-on-UMb interference corrections. Offline re-calibration of the Th calibration on the Th-rich reference monazite, to match its nominal age, is an essential part of the protocol. EPMA-Th-U-Pb data are checked in ThO2*-PbO coordinates for matching isochrones along regressions forced through zero. Error calculations of monazite age populations are performed by weighted average routines. Depending on the number of analyses and spread in ThO2*-PbO coordinates, minimum errors <10 Ma are possible and realistic for Paleozoic monazite ages. A test of the protocol was performed on two garnet metapelite samples from the Paleozoic metamorphic Zone of Erbendorf-Vohenstrauß (NE-Bavaria, western Bohemian Massif).

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Nachlas, William, Suzanne Baldwin, Jay Thomas i Michael Ackerson. "Investigation of N in Ammonium-bearing Silicates with Electron Probe Microanalysis (EPMA)". Microscopy and Microanalysis 26, S2 (30.07.2020): 42–43. http://dx.doi.org/10.1017/s1431927620013203.

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Tsuji, Kouichi. "Grazing-exit electron probe X-ray microanalysis (GE-EPMA): Fundamental and applications". Spectrochimica Acta Part B: Atomic Spectroscopy 60, nr 11 (listopad 2005): 1381–91. http://dx.doi.org/10.1016/j.sab.2005.08.013.

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Duque, Laura, Fernanda Guimarães, Helena Ribeiro, Raquel Sousa i Ilda Abreu. "Elemental characterization of the airborne pollen surface using Electron Probe Microanalysis (EPMA)". Atmospheric Environment 75 (sierpień 2013): 296–302. http://dx.doi.org/10.1016/j.atmosenv.2013.04.040.

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Tormey, J. McD, i E. S. Wheeler-Clark. "Electron Probe X-Ray Microanalysis of Cardiac Muscle: Progress Report". Proceedings, annual meeting, Electron Microscopy Society of America 43 (sierpień 1985): 18–21. http://dx.doi.org/10.1017/s0424820100117200.

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Myocardial contractility is primarily controlled by the moment to moment concentration of ionized Ca around the myofibrils. This concentration in turn is determined by a large number of factors, including gradients of various electrolytes across cell membranes and the concentrations of Ca in various subcellular compartments. The latter include sarcoplasmic reticulum (SR), mitochondria, binding sites associated with sarcolemmae and T-tubules, and binding sites within the sarcoplasm itself. A central problem in cardiac physiology has been to determine the functional interrelationships among these subcellular compartments.Electron probe x-ray microanalysis (EPMA) is the method of choice for directly measuring the concentrations within subcellular compartments of cells, and thus offers an unique opportunity to resolve the interpretive uncertainties inherent in alternative methods. Indeed, this method has yielded impressive results when applied by Soralyo et al. to a similar analytical problem in skeletal muscle.

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Cazaux, Jacques. "About the Mechanisms of Charging in EPMA, SEM, and ESEM with Their Time Evolution". Microscopy and Microanalysis 10, nr 6 (grudzień 2004): 670–84. http://dx.doi.org/10.1017/s1431927604040619.

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The physical mechanisms involved in electron irradiation of insulating specimens are investigated by combining some simple considerations of solid-state physics (trapping mechanisms of electrons and secondary electron emission) with basic equations of electrostatics. To facilitate the understanding of the involved mechanisms only widely irradiated samples having a uniform distribution of trapping sites are considered. This starting hypothesis allows development of simple models for the trapped charge distributions in ground-coated specimens as investigated in electron probe microanalysis (EPMA) as well as for the bare specimens investigated in scanning electron microscopy (SEM) and environmental SEM (ESEM). Governed by self-regulation processes, the evolution of the electric parameters during the irradiation are also considered for the first time and practical consequences in EPMA, SEM, and ESEM are deduced. In particular, the widespread idea that the noncharging condition of SEM is obtained at a critical energyE2(where δ + η = 1 with δ and η yields obtained in noncharging experiments) is critically discussed.

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Remond, G., R. H. Packwood, C. Gilles i S. Chryssoulis. "Layered and ion implantation specimens as possible reference materials for the electron-probe microanalysis". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 2 (sierpień 1992): 1652–53. http://dx.doi.org/10.1017/s0424820100132893.

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Merits and limitations of layered and ion implanted specimens as possible reference materials to calibrate spatially resolved analytical techniques are discussed and illustrated for the case of gold analysis in minerals by means of x-ray spectrometry with the EPMA. To overcome the random heterogeneities of minerals, thin film deposition and ion implantation may offer an original approach to the manufacture of controlled concentration/ distribution reference materials for quantification of trace elements with the same matrix as the unknown.In order to evaluate the accuracy of data obtained by EPMA we have compared measured and calculated x-ray intensities for homogeneous and heterogeneous specimens. Au Lα and Au Mα x-ray intensities were recorded at various electron beam energies, and hence at various sampling depths, for gold coated and gold implanted specimens. X-ray intensity calculations are based on the use of analytical expressions for both the depth ionization Φ (ρz) and the depth concentration C (ρz) distributions respectively.

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Chia, V. K. F., R. J. Bleiler, C. L. Anderson i R. W. Odom. "Quantitative Trace Element Analysis of Micro-Samples by SIMS". Proceedings, annual meeting, Electron Microscopy Society of America 48, nr 2 (12.08.1990): 360–61. http://dx.doi.org/10.1017/s042482010013540x.

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A number of researchers have applied secondary ion mass spectrometry (SIMS) in various areas of medical research. The potential of SIMS as an analytical tool in elemental microanalysis of biological specimens lies in its sub-part per million (ppm) elemental detection sensitivities and its ability to generate two and three dimensional distributions of the intensities of mass selected secondary ions. Established techniques such as inductively coupled plasma (ICP) and electron probe microanalysis (EPMA) are also capable of sub-ppm elemental detection limits. ICP detection limits are adversely affected as the sample volume decreases below 1 milliliter. The EPMA technique can achieve ppm detection limits with volumes in the 100 picoliter range but its detection limits do not decrease as the sample volume increases. SIMS combines excellent detection sensitivities with small sample masses (picogram) which makes it a very useful complementary technique to ICP and EPMA especially for minor and trace element level analyses in small volumes of biological fluids.

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Keil, K., R. Fitzgerald i KFJ Heinrich. "Celebrating 40 years of energy dispersive X-ray spectrometry in electron probe microanalysis (EPMA)". Microscopy and Microanalysis 14, S2 (sierpień 2008): 1152–53. http://dx.doi.org/10.1017/s1431927608081221.

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Carpenter, PK. "Electron-Probe Microanalysis (EPMA): An Overview for Beginners and a Status Report for Experts". Microscopy and Microanalysis 14, S2 (sierpień 2008): 1150–51. http://dx.doi.org/10.1017/s1431927608088806.

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Song, Jian Li, Qi Lin Deng, C. Y. Chen i De Jin Hu. "Experimental Study on the Laser Direct Fabrication of Stainless Steel Components". Key Engineering Materials 315-316 (lipiec 2006): 239–43. http://dx.doi.org/10.4028/www.scientific.net/kem.315-316.239.

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Experimental study on the laser direct fabrication (LDF) of stainless steel powder is carried out. Microstructure and properties of the deposited components are analyzed and tested with optical microscopy (OM), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) etc. Cracking generation mechanisms of this material are investigated, corresponding cracking control strategies have been proposed. Finally, fully dense stainless steel components free of defects and with perfect comprehensive mechanical properties have been produced.

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Somlyo, A. P. "Where Art Thou, Calcium?" Microscopy and Microanalysis 3, S2 (sierpień 1997): 913–14. http://dx.doi.org/10.1017/s1431927600011454.

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Ever since the recognition of calcium as a major intracellular messenger of signal transduction, its subcellular localization and intracellular movements have been intensively sought through electron and light optical methods. Electron probe microanalysis (EPMA), X-ray mapping, electron energy-loss spectroscopy (EELS) and energy-filtered imaging still provide the highest spatial resolution for measuring total calcium, whereas with light optical methods (fluorescent, luminescent and absorbance dyes) free [Ca2+]i can be measured with high sensitivity and time resolution. This presentation will summarize the relationship, whether collision or convergence, between the results of electron and light optical methods, with particular reference to mitochondrial Ca, and consider the potential for further improvements in detection sensitivity and spatial resolution.Sarcoplasmic and endoplasmic reticulum: Early attempts to quantitate Ca in cellular organelles with EPMA were directed at the sarcoplasmic reticulum (SR) of skeletal muscle, where EPMA could also address questions not amenable to studies of isolated SR.

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Vykhodets, V. B., Tatiana Eugenievna Kurennykh i N. U. Tarenkova. "Study of Distribution of Impurity Atoms in Metallurgical Macrodefects". Defect and Diffusion Forum 273-276 (luty 2008): 707–12. http://dx.doi.org/10.4028/www.scientific.net/ddf.273-276.707.

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Using nuclear microanalysis (NRA) and electron probe microanalysis (EPMA), concentrations of carbon, oxygen, nitrogen, aluminum, and vanadium were measured on a large group of macrodefects formed in the course of smelting titanium alloys. A remarkable enrichment of the defect material in oxygen and nitrogen atoms was detected; histograms of defect distribution over the concentrations of oxygen, nitrogen, aluminum, and vanadium were obtained. The above results agree with the concepts according to which the defects are formed from the particles that have the melting temperature higher then the temperature of smelting.

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