Characterization homogeneity

NIST s first four certified reference materials were steel samples, and these were followed by many others. The program supplied analytically well characterized homogeneous materials. This program included, from the beginning, homogeneity... 

Final physical characterization Chemical characterization (homogeneity)... 

Characterization of the finally-produced material includes final physical characterization along the lines described under interim physical characterization and chemical characterization (homogeneity). The latter includes selection, development, assessment, and validation of methodologies for homogeneity testing includ-... 

Danzer 1984 Liebich et al. 1989 Liebich 1995). A complete strategy for characterizing homogeneity is elaborated to provide sufficient information on the behavior of elements in solid materials. 

Thus, the selectivities, deactivation mechanisms, and potential transformations of alkoxo and amido intermediates in such reactions are not well understood. It is even rare for transition metal amido and alkoxo complexes to be clearly identified as intermediates in catalytic chemistry. The hydrogenation of imines and ketones presumably involves such intermediates [68], but they have not been clearly detected in these reactions [69]. The catalytic reduction of CO on surfaces may involve alkox-ides, but well-characterized homogeneous analogs are unusual [58]. 

Another combination catalyst that includes a Lewis acid component is Cp2MCl2/2n-BuLi/B(C6F5)3.60-61 Interest in such systems came about as a consequence of the successful use of well-characterized homogeneous cationic and cation-like Group 4 and actinide metallocene catalysts for olefin polymerization.62 63... 

NBS (12) maintains a comprehensive program on standard reference materials (SRMs) SRMs are well-characterized, homogeneous, stable materials or simple artifacts with specific properties measured and certified by NBS. They are widely used in a variety of measurement applications, including the evaluation of the accuracy of test methods, improvement of measurement compatability among different laboratories, and establishment of measurement traceability to NBS. The Bureau currently has more than 1000 different SRMs available. ... 

Ethylene polymerization catalyzed by the well-characterized homogeneous lanthanide complexes [M(C5H R)2 ] 2 been studied. 

We have initiated investigations intended to characterize homogeneous carbon dioxide reduction processes and our results to date are summarized herein. Specifically, our research centers on mechanistic studies of metal carbonyl anion catalysts, which readily activate CO2 to C-H and C-C bond formation, two of the most important processes in the synthesis of organic materials. 

As a rule, one does not specify the amounts of substance of all the components in order to characterize homogeneous mixtures, but the content of selected components. The superordinate concept content meaning the material fraction of a substance in the mixture can be quantified by various measures of composition. Several of these measures will be introduced in the following. 

Quantitative Analysis. Quantitative analysis is based on the assumption that the intensity of the Lorentzian X-ray peak is proportional to the number of atoms of the species responsible for the peak. Since the theoretical relations are complicated and involve a large number of parameters, some of which are difficult to evaluate, well-characterized homogeneous standards are generally used for calibration, the composition of which has been determined by classical chemical macroscopic methods. These standards, which should also have similar shapes to the sample, are then measured in EDS equipment under the same well-defined and reproducible conditions as the unknown sample, and the. spectra are compared. This calibration leads to the so-called kj factors (coef-... 

Fig. 19.7 Strrface resistance mapping (m test method the characterize homogeneity) o wo ig temperature PEM bipolar plates, (a) The materia s ows a higher resistance at the edges with 80 % of ta pomts... 

Among the broad possibilities to characterize homogeneity, up to now, the mixing indices based on the standard deviation of sample concentrations have remained the most frequently used quality indicators. One of them was defined by Rose [2, 3], as... 

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