Environmental TEM, A CTF Approach for Atmospheric Lattice Imaging
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Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.Keywords:
Microanalysis
Energy dispersive X-ray spectroscopy (EDS) is a microanalysis technique for material characterization that can provide accurate quantification of elemental composition while maintaining high spatial resolution. EDS microanalysis studies on cementitious materials can face several challenges essentially due to the complex chemical and mineralogical characteristics of cement hydration products. Furthermore, EDS microanalysis is widely carried out in "standardless analysis" mode, which relies on the internal standards of the microanalysis software. This can lead to highly erroneous analysis results because standardless analysis typically normalizes total to 100% without taking chemically bound water into account. In the case of quantifying chlorine content of a cement paste, such normalization is unacceptable because it can lead to overestimation. For accurate determination of elemental concentrations, X-ray spectra collected from minerals or glasses with known chemical compositions are necessary as references. This paper examines the performance of six different minerals containing a wide range of chlorine concentrations as standards for quantitative EDS microanalysis. Also, the influence of experimental conditions such as beam current, accelerating voltage, dwell time, and scanning mode on the obtained results is discussed. It was found that among the minerals investigated, scapolite [(Na,Ca)4(Al3Si9O24)Cl] stands out as the most favorable microanalysis standard for quantifying chlorine content in cement paste.
Microanalysis
Cementitious
Energy-dispersive X-ray spectroscopy
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Microanalysis
Flow injection analysis
Qualitative analysis
Quantitative Analysis
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Porous SiC Ceramics with Multiple Pore Structure Fabricated via Gelcasting and Solid State Sintering
Porous SiC ceramics with multiple pore structures were fabricated via gelcasting and solid state sintering.A novel gelling agent of Isobam was applied and PMMA was used as both foam stabilizer and pore forming agent.The mechanical properties of porous SiC ceramics were investigated as functions of PMMA content, rotating speed of ball mill, and sintering temperature.With PMMA content increasing from 5wt% to 20wt%, the foaming effect was inhibited while the stability of bubbles increased.When the rotating speed was 220 r/min, the open porosities of the as-prepared SiC ceramics sintered at 2100 varied ℃ from 51.5% to 72.8%, and compressive strength varied from 7.9 to 48.2 MPa.With the rotating speed increasing from 220 to 280 r/min, the foaming effect was aggravated and the porosities of SiC ceramics sintered at 2100 increased.℃ While the sintering temperature increasing from 2050 to 2150 , ℃ the SiC ceramics prepared with PMMA content of 20wt% at rotating speed of 220 r/min decreased in the open porosities while increased in compressive strength.
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Abstract Secondary ion mass spectrometry (SIMS) has inherent features of high sensitivity, great dynamic range, and capability to provide spatially resolved chemical information making it well suited for trace and microanalysis of diverse materials. The various SIMS methods used to derive the boron distribution in hepatoma cells, to investigate the intcr‐iayer reactions in multi‐layer ceramic structural materials, and to evaluate the effects of fabrication on microstructural and functional properties in semiconductor devices, are presented to illustrate possible roles of SIMS in microanalysis.
Microanalysis
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Abstract Many diseases are associated with a change in the distribution of diffusible ions at the cell or tissue level. These diseases can profitably be studied by X‐ray microanalysis. This technique for the study of ion distribution requires the use of cryoprepared specimens. Analysis at low or medium resolution can be carried out on thick or semi‐thick cryosections, or on frozenhydrated or freeze‐dried embedded bulk samples. Such analyses are particularly useful in the initial stages of an investigation or when data from a large number of samples have to be acquired. Also X‐ray microanalysis of cultured or single cells prepared by freeze‐drying can be used to rapidly collect information on a large number of cells. Analysis at high resolution has to be carried out on thin sections: Cryosections or sections of freeze‐substituted or freeze‐dried embedded tissue. For the latter type of specimens, the use of low‐temperature embedding methods may have important advantages.
Microanalysis
Biological specimen
Electron probe microanalysis
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Microanalysis
Sample (material)
Flow injection analysis
Electron probe microanalysis
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Erythrocytes in human blood were used to evaluate the reliability of cryopreparation techniques for electron probe X-ray microanalysis of biological cells and tissues. The elemental content determined by X-ray microanalysis of ultrathin freeze-dried cryosections was found to be consistent with data known from the literature. Considerable redistribution of the intracellular elemental composition was found after freeze-substitution as well as after freeze-drying followed by resin embedding. Two conclusions are drawn from this study: 1. Erythrocytes in human blood are a suitable reference specimen for evaluation of specimen preparation techniques for microanalysis. 2. At present, freeze-dried cryosections are the most reliable specimen type for quantitative electron probe microanalysis of cells.
Microanalysis
Electron probe microanalysis
Human blood
Biological specimen
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Nanocrystalline material
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