摘要 :
The scanning electron microscope (SEM) has become a must-have for any research institution, university, or industry involved in material production, treatment, processing, research or even distribution. The SEM has evolved into pr...
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The scanning electron microscope (SEM) has become a must-have for any research institution, university, or industry involved in material production, treatment, processing, research or even distribution. The SEM has evolved into probably the most common analytical tool in the materials research community, with its imaging, elemental analytics, phase analyses, local micro-stress analyses. in-situ cross-section preparation, lamella preparation for TEM. etc. Since the number of SEMs has drastically increased, due to its availability and its wide range of uses, increasing numbers of poorly trained SEM operators are involved in materials research and development. The resulting problem is that all analytical instruments always show "something" and the operator must know the limitations of the technique. The skilled and properly trained operator understands the physics behind the SEM and its associated analytical techniques. such as EDS, WDS, SIMS, EBSD, BEI, and ECCI.
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Technology Acceptance Model (TAM) employed statistics method to validate the relation between constructs in the model. SEM is the most often statistics method that used in TAM analysis. Small sample is crucial problem in Structura...
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Technology Acceptance Model (TAM) employed statistics method to validate the relation between constructs in the model. SEM is the most often statistics method that used in TAM analysis. Small sample is crucial problem in Structural Equation Modelling (SEM). SEM with Bayesian approach and SEM-PLS are the altematives solution for small sample problem in SEM. The main differentiation between SEM-PLS and SEM Bayesian is how to develop resampling for small samples. This study will compare SEM with Bayesian approach and SEM-PLS in TAM analysis.
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For almost 40 years structural equation modeling (SEM) has been the statistical tool of choice for the assessing measurement and structural relationships in the social sciences. During the initial 30 years almost all applications ...
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For almost 40 years structural equation modeling (SEM) has been the statistical tool of choice for the assessing measurement and structural relationships in the social sciences. During the initial 30 years almost all applications of SEM utilized what has become known as covariance-based SEM. But in the past ten years an alternative structural equation modeling method, composite-based SEM, has increasingly been applied. In fact, a substantial number of social sciences scholars consider composite-based SEM the method of choice for structural equation modeling applications. In this paper, I provide an overview of the evolution of SEM, from the early years when factor-based SEM was the dominant method to the more recent years as composite-based methods have become much more prevalent. I also summarize several relevant composite-based topics including the emergence of composite-based SEM, confirmatory composite analysis (CCA), and a new method of generalized structured component analysis (GSCA). In the final section I propose some observations about current developments and future opportunities for composite-based SEM methods.
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The scanning electron microscope (SEM) historically has been used mainly as an image-producing device and, in spite of certain obvious and sometimes serious electronics problems, serves in this function as an acceptable and effect...
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The scanning electron microscope (SEM) historically has been used mainly as an image-producing device and, in spite of certain obvious and sometimes serious electronics problems, serves in this function as an acceptable and effective instrument for many applications. Today, the SEM is being used in areas other than imaging. The major area of current use and of concern of this Workshop paper is SEM-based metrology. SEM-based metrology is of great interest to the microelectronics industry, and for this industry, measurement accuracy and repeatability issues have become paramount. This paper presents a short description of some of the electrical properties of different components of an SEM which can seriously affect its performance as a metrology tool. These include the electronics associated with the formation of the electron beam and scanning circuitry, the electron detectors, the video signal chain, and the analog-to-digital (AD) and digital-to-analog (DA) conversion circuits. This discussion relates the possible influences generated by these components to the detected and observed signal. This paper also includes the concept that computer modeling of the SEM image, with Monte Carlo or other techniques, must be done completely in order to be meaningful. Modeling just the electron beam/sample interactions alone only deals with a portion of the issues. Any modeling must include the shortcomings of the real, nonideal measuring tool. By knowing the electrical characteristics and possible imperfections caused by the different parts of an SEM, a more accurate comparison of the measured and calculated signal can be made. One practical example is presented which demonstrates how it is possible to improve the agreement between calculated and measured signals.
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The discovery of a new population of the non-marine heterotardigrade Novechiniscus armadilloides from Utah, USA, allowed us to reanalyse the species by means of scanning electron microscopy and differential interference contrast m...
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The discovery of a new population of the non-marine heterotardigrade Novechiniscus armadilloides from Utah, USA, allowed us to reanalyse the species by means of scanning electron microscopy and differential interference contrast microscopy. This analysis confirmed the presence of bar shaped, impaired segmental plates and of a long filament E in addition to the filament A always present in the class Heterotardigrada. It also provided additional information on characters not explicitly cited in the previous descriptions of this monotypic genus, such as details of the head cirri and clavae, details of the buccal tube and pharyngeal bulb, sculpture of the dorso-lateral and leg plates, details of the claws. The population is bisexual, but no secondary sexual dimorphism was observed. The male and female gonopores were described. New characters such as red eyes and red body colour were used in analysing the phylogeny of the family Echiniscidae. The phylogeny and biogeography of non-marine heterotardigrades provide intriguing questions for further research. (C) 2007 Gesellschaft fur Biologische Systematik. Published by Elsevier GmbH. All rights reserved.
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For almost three decades IXRF has been designing and manufacturing high-end X-ray Microanalysis systems that are fitted to Scanning Electron Microscopes (SEM/EDS). Almost 10 years ago, IXRF developed SEM-XRF microscope attachments...
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For almost three decades IXRF has been designing and manufacturing high-end X-ray Microanalysis systems that are fitted to Scanning Electron Microscopes (SEM/EDS). Almost 10 years ago, IXRF developed SEM-XRF microscope attachments allowing broader elemental analysis coverage. In 2014, IXRF launched the ATLAS series of general purpose, microxRF energy dispersive X-ray fluorescence (micro-XRF) spectrometers for elemental analysis and hyperspectral imaging of elements from sodium (Na) through uranium (U). IXRF specialises in: SEM/ EDS, SEM-XRF and micro-XRF.
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Strangles is the main upper respiratory tract disease of horses. There are currently no studies on the changes in alleles of the M protein gene (seM) in Brazilian isolates of Streptococcus equi ssp. equi (S. equi). This study aime...
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Strangles is the main upper respiratory tract disease of horses. There are currently no studies on the changes in alleles of the M protein gene (seM) in Brazilian isolates of Streptococcus equi ssp. equi (S. equi). This study aimed to analyze and differentiate molecularly S. equi isolates from equine clinical specimens from southern Brazil, between 1994 and 2010. seM alleles were analyzed in 47 isolates of S. equi obtained from clinical cases of strangles (15 Thoroughbred horses, 29 Crioulo breed horses and three Brasileiro de Hipismo - BH). seM alleles characterization was performed by comparing variable region sequences of the seM gene. The alleles were also phylogenetically grouped by Neighbor-joining analysis, which demonstrated the geographic distribution of those in properties from southern Brazil. Fifteen alleles of the gene seM were found among the 47 S. equi isolates analyzed. Among these, only one allele (seM-61), which was identified in seven isolates (14.9%), was found in the database PubMLST-seM. Within the new alleles, allele seM-115 was the most prevalent, having been found in 13 isolates (27.7%), followed by allele seM-117 in 10 isolates (21.3%). In the Brazilian horse population studied, there is greater diversity of M protein alleles in S. equi isolates compared to worldwide data deposited in PubMLST-seM. Among the 15 seM alleles identified, only one allele sequence was previously published. The alleles identification is important to control the disease by guiding selection of strains for the manufacture of commercial and autogenous vaccines.
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A versatile in situ measuring system in a SEM with four independently moveable tips was developed. The system allows manipulation as well as electrical contacting of objects on the micro- and nanometer scale. The SEM provides a hi...
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A versatile in situ measuring system in a SEM with four independently moveable tips was developed. The system allows manipulation as well as electrical contacting of objects on the micro- and nanometer scale. The SEM provides a high vacuum (HV) chamber, but also a variable pressure (VP) mode which allows imaging of conducting or nonconducting objects and surfaces. In this work, we show the experimental setup and capabilities of this system while measuring a platinum surface.
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Researchers have devoted some time and effort to developing methods for fitting nonlinear relationships among latent variables. In particular, most of these have focused on correctly modeling interactions between 2 exogenous laten...
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Researchers have devoted some time and effort to developing methods for fitting nonlinear relationships among latent variables. In particular, most of these have focused on correctly modeling interactions between 2 exogenous latent variables, and quadratic relationships between exogenous and endogenous variables. All of these approaches require prespecification of the nonlinearity by the researcher, and are limited to fairly simple nonlinear relationships. Other work has been done using mixture structural equation models (SEMM) in an attempt to fit more complex nonlinear relationships. This study expands on this earlier work by introducing the 2-stage generalized additive model (2SGAM) approach for fitting regression splines in the context of structural equation models. The model is first described and then investigated through the use of simulated data, in which it was compared with the SEMM approach. Results demonstrate that the 2SGAM is an effective tool for fitting a variety of nonlinear relationships between latent variables, and can be easily and accurately extended to models including multiple latent variables. Implications of these results are discussed.
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