Analyzing crystals, properties

Descriptor ranges were derived by analyzing the properties of building blocks (residues) of 14 potent peptidomimetic and nonpeptidic HIV PR inhibitors, for which crystal structures of inhibitor PR complex have been published in the Protein Data Bank [25],... 

The double-hump shape of the free energy curve in Figure 15.3a has one other implication of interest to Earth scientists, metallurgists, materials scientists, and other people who work with solid solutions. This is a more subtle point, important in growing synthetic crystals or in analyzing exsolution properties in minerals. The two points marked Si and S2 are flex points of the free energy curve. Flex points (like the center point in the letter S) can be found from the second derivative of the curve, i.e., where... 

Finally, the transversal streaks seen in the RLM (marked 4 in Fig. 1.19) are due to residual scattering from the analyzer crystals used in the high resolution configuration shown in Fig. 1.17 these analyzer streaks approximately follow the direction along the surface of the Ewald sphere and are typically detected near strong diffraction peaks (they are artifacts from the technique and bear no consequence in the interpretation of the materials properties). 

Because of the existence of numerous isomers, hydrocarbon mixtures having a large number of carbon atoms can not be easily analyzed in detail. It is common practice either to group the constituents around key components that have large concentrations and whose properties are representative, or to use the concept of petroleum fractions. It is obvious that the grouping around a component or in a fraction can only be done if their chemical natures are similar. It should be kept in mind that the accuracy will be diminished when estimating certain properties particularly sensitive to molecular structure such as octane number or crystallization point. 

In a previous work we showed that we could reproduce qualitativlely the LMTO-CPA results for the Fe-Co system within a simple spin polarized canonical band model. The structural properties of the Fe-Co alloy can thus be explained from the filling of the d-band. In that work we presented the results in canonical units and we could of course not do any quantitative comparisons. To proceed that work we have here done calculations based on the virtual crystal approximation (VGA). In this approximation each atom in the alloy has the same surrounding neighbours, it is thus not possible to distinguish between random and ordered alloys, but one may analyze the energy difference between different crystal structures. 

When solid particles are subject to noncatalytic reactions, the effects of the reaction on individual particles are derived and then the results are averaged to determine overall properties. The general techniques for this averaging are called population balance methods. They are important in mass transfer operations such as crystallization, drop coagulation, and drop breakup. Chapter 15 uses these methods to analyze the distribution of residence times in flow systems. The following example shows how the methods can be applied to a collection of solid particles undergoing a consumptive surface reaction. 

A study on the effectiveness of the E-plastomers as impact modifiers for iPP was carried out in relation to the traditional modifier EPDM. In this study, the flow properties of the E-plastomer-iPP and EPDM-PP blends were also evaluated. The blends were analyzed by solid-state 13C-nuclear magnetic resonance (NMR) spectroscopy, microscopy (SEM), and DSC. The results showed that E-plastomer-PP and EPDM-PP blends present a similar crystallization behavior, which resulted in a similar mechanical performance of the blends. However, the E-plastomer-PP blend presents lower torque values than the EPDM-PP blend, which indicates a better processibility when E-plastomer is used as an impact modifier for iPP. 

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