Structures high amplitude

If, on the other hand, blast modeling is a starting point for structural analysis, the TNT-blast model is less satisfactory because TNT blast and gas explosion blast differ substantially. Whereas a TNT charge produces a shock wave of very high amplitude and short duration, a gas explosion produces a blast wave, sometimes shockless, of lower amplitude and longer duration. In structural analysis, wave shape and positive-phase duration are important parameters these can be more effectively predicted by techniques such as the multienergy method. 

The main sources of error in charge density studies based on high-resolution X-ray diffraction data are of an experimental nature when special care is taken to minimise them, charge density studies can achieve an accuracy better than 1% in the values of the structure factor amplitudes of the simplest structures [1, 2]. The errors for small molecular crystals, although more difficult to assess, are reckoned to be of the same order of magnitude. 

When low-temperature studies are performed, the maximum resolution is imposed by data collection geometry and fall-off of the scattered intensities below the noise level, rather than by negligible high-resolution structure factor amplitudes. Use of Ag Ka radiation would for example allow measurement of diffracted intensities up to 0.35 A for amino-acid crystals below 30 K [40]. Similarly, model calculations show that noise-free structure factors computed from atomic core electrons would be still non-zero up to O.lA. 

Fio. 6. Spectra of variety of manganese compounds MnF4 has high amplitude, MnS low amplitude fine structure. 

This effect is also demonstrated in Fig. 9 showing a comparison of 2 substrates with high and low surface structure. The amplitude of the structures is reduced, but the basic structure of the substrate is partially transferred through each single coating layer and influences finally the topcoat appearance. These results are very important due to the effect, that the substrate structure clearly influences the final coating structure. Based on surface structure measurements a preselection of plastics substrates can be done to obtain an optimal structure (smoothness) of the coating system applied. 

FIGURE 9.2. The relationship between a high-amplitude electron-density wave (left, traveling vertically) and periodicity in the structure (right). The repeat unit is indicated at the far right. The 10 0 0 electron-density wave is intense (see Figure 3.16. Chapter 3) for DNA-like structures. The repeat unit is 34 A long and the distance... 

Two structural abnormahties in the mitochondria are considered important pathogenetic factors during ischemia. One is characterized by pore formation in the itmer mitochondrial membrane and high amplitude swelling (mitochondrial permeability transition or MPT) [30, 31]. The second involves leakage of cytochrome C from the inter-membrane space into the cytosol [32]. Because of its role as an electron shuttle, dislocation of cytochrome c compromises respiration [33, 34], and as a cytosolic cofactor cytochrome C activates caspase 9, and triggers apoptosis [33-35] (see below). 

The central problem in crystallography lies in obtaining the phase for every observed structure factor amplitude. We judge how correct a given set of phases is by the result does the electron density map make chemical sense For small molecules, very accurate data is usually available to high resolution (1 A or better), which allows the use of direct methods 9 to obtain the phases rapidly and correctly. The approach uses statistical relationships between the phases of certain reflections. Unfortunately, direct methods are not easily... 

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