Spatial geometry

Correlation time (t,) A parameter related to the mean time during which a molecule maintains its spatial geometry between successive rotations. For... 

To describe the diffusion of solutes in the rhizosphere, where concentration gradients change with time, /, as well as space, mass conservation is invoked with the spatial geometry appropriate for the cylindrical root (8) ... 

A second example has been addressed in which the synthesis and potential application of a series of neutral O-glycosylated porphyrin dimers and two original O-glycosyl cationic dimers were examined in PDT. In order to understand the influence of the number of glycosyl moieties, the spatial geometry and the ionic character on their photodynamic activity was evaluated.144 The in vitro results... 

Baumann J. and Fayes M. D. (1986) Excitation Energy Transfer in Disordered Two-Dimensional and Anisotropic Three-Dimensional Systems Effects of Spatial Geometry on Time-Resolved Observables, J. Chem. Phys. 85, 4087-4107. 

Considering the spatial geometry of cerebral capillaries and capillary blood flow, a number of dynamic models of the blood-brain barrier have been developed, in which endothelial cells are cultured inside a permeable tube, the outer surface of which is coated with astrocytes. Supply of the cells with nutrients and artificial blood flow are maintained by using a peristaltic pump system [112, 113]. 

Figure 3.1 Principle illustration of scale-related concepts of constitutional and distributional heterogeneity. The constitutional heterogeneity, CHL, expresses all between-fragment compositional differences in the entire lot, while the distributional heterogeneity, DHL, reflects all between-increment (between-group) compositional differences, which can be seen as covering the entire spatial geometry of the lot.

The following sections will present some of the most important analytical methods [4] employed in determining the chemical composition, the molecular mass, the morphology, the spatial geometry, and the homogeneity of dendrimers. 

For comparison, we present below the G2(MP2)-calculated heat effects AH (OK) of the Si = O bond rupture for a number of silanone molecules containing different substituents on the silicon atom. The calculations were carried out for the molecules of C2v symmetry, with the spatial geometry of the starting silylene molecules corresponding to the situation where the SiOSiO atoms in the (H3Si-0)2Si and (F3Si-0)2Si molecules are trans-positioned, while the HOSiO atoms in the (HO)2Si molecule are cis to each other, and this symmetry is retained upon the formation of the silanone group ... 

Fig. 7.7. Spatial geometries (DFT) of the radicals which were used for studying the influence of chemical nature of substituents at /7-Si atoms on the radical EPR parameters (see Table 7.5).

Thus inhomogeneous broadening of ESR spectra of bulk radicals is caused by different factors. Based on the results of quantum-chemical calculations the observed differences in EPR constants of various groups of radicals could be related to variations in their spatial geometry, namely to different positions of /1-Si atoms. We have calculated the distribution... 

Quantitative information concerning this precrystalline phase is difficult to obtain consequently the influence of spatial geometry upon the course of a catalytic reaction is more readily interpretable in terms of Balandin s theory than Kobozev s. The latter theory does have the advantage that the action of poisons and promoters can be formulated in terms of their influence upon the activity of the ensemble. 

The spatial geometry of disclination reactions in bulk mesophase has recently been presented by Zimmer and Weitz (29) Working with coarse-structured mesophase prepared by lengthy pyrolysis of A240 petroleum pitch at 400°C, they defined the disclination arrays on a succession of polished sections spaced at about 7 ym. In this way a +tt disclination was traced through a branching point (i.e., a reaction point) to form a -tt and a +2tt disclination. Thus a reaction... 

The tests cannot be extrapolated directly to field reservoir performance because the spatial geometry is different. The core tests have a linear, 1-dimensional flow geometry while the actual reservoir has radial, 3-dimensional flow. In 3-dimensional flow the displacement efficiency is typically less than that measured in linear displacement studies. Chilton (1987) showed in his computer simulation studies that, as compared with the linear flow case, the predicted oil produced was 10% less for the two-dimensional model and 27% less for the three-dimensional model. However, when mobility control was used with a tenfold decrease in carbon dioxide mobility, the calculated improvement in displacement efficiency was much less for the linear case than the three-dimensional case. This result indicates that the increase in displacement efficiency under field conditions should be greater than that recorded in these linear laboratory tests. 

Size and the spatial geometry of nanostructured arrays or aggregates which also allow for plasmonic manipulation of the substrate optimization of the fluorophore-nanostructure distance orientation of the fluorophore on the metallic surface. 

The next step is to derive a relation between, J and K. It is a matter of taste, or convenience, which of these variables to take as the independent variable. For adsorption from dilute solutions it is customary to take the concentration (i.e. g ) as independent. On the other hand, for many theoretical analyses it is easier to assume a certain spatial geometry and then And out the g of the solvent with which the curved interface is at equilibrium. Let us foUow the second route, i.e. we want to establish dg / 3J rmd dg / 8K. These differential quotients can be obtained from [4.7.11 by changing variables and cross-differentiation. For instance. 

Lewis diagrams show how bonds connect the atoms in a molecule, but they do not show the spatial geometry of the molecule. The ammonia molecule is not planar, but pyramidal, for example, with the nitrogen atom at the apex. The water molecule is bent rather than straight. Three-dimensional geometries can be represented by ball-and-stick models (such as those shown in Fig. 3.14). 

One of the most useful aspects of NMR compared with other types of spectroscopy is the elucidation of spatial geometry. Modem high-held instm-ments give spectra in which the hne structure of the signals is more clearly resolved but may still not always show hrst-order coupling. The analysis of... 

Spatial geometry Cartesian Cylindrical Spherical Revolute... 

Enzyme binding sites. An enzyme binds the substrates of the reaction and converts them to products. The substrates are bound to specific substrate binding sites on the enzyme through interactions with the amino acid residues of the enzyme. The spatial geometry required for all the interactions between the substrate and the enzyme makes each enzyme selective for its substrates and ensures that only specific products are formed. 

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