Motional behavior

The values of the time constants and are important in understanding both internal and overall motional behavior of the sample molecule. values are measured by the inversion recovery pulse sequence ... 

Fabrication processing of these materials is highly complex, particularly for materials created to have interfaces in morphology or a microstructure [4—5], for example in co-fired multi-layer ceramics. In addition, there is both a scientific and a practical interest in studying the influence of a particular pore microstructure on the motional behavior of fluids imbibed into these materials [6-9]. This is due to the fact that the actual use of functionalized ceramics in industrial and biomedical applications often involves the movement of one or more fluids through the material. Research in this area is therefore bi-directional one must characterize both how the spatial microstructure (e.g., pore size, surface chemistry, surface area, connectivity) of the material evolves during processing, and how this microstructure affects the motional properties (e.g., molecular diffusion, adsorption coefficients, thermodynamic constants) of fluids contained within it. 

A reevaluation of molecular structure of humic substances based on data obtained primarily from nuclear magnetic resonance spectroscopy, X-ray absorption near-edge structure spectroscopy, electrospray ionization-mass spectrometry, and pyrolysis studies was presented by Sutton and Sposito (2005). The authors consider that humic substances are collections of diverse, relatively low molecular mass components forming dynamic associations stabilized by hydrophobic interactions and hydrogen bonds. These associations are capable of organizing into micellar structures in suitable aqueous environments. Humic components display contrasting molecular motional behavior and may be spatially segregated on a scale of nanometers. Within this new structural context, these components comprise any molecules... 

Recent theoretical investigations suggest that the discrepancy between theoretical and experimental values of the hopping rate is due to the underestimation of localization phenomena in the description of charge motion behavior. These phenomena can result from the coupling of electronic motion to vibrational dynamics of base pairs [47] and can also be caused by polarization of the molecule or solvent [34, 48]. In the latter case theoretically possible effects include ... 

Irradiated polyethylene exhibits different effects on the two observed broad and narrow components 26 27,28 29). The first effect of irradiation on motional behavior... 

CARBON-13 NUCLEAR MAGNETIC RELAXATION AND MOTIONAL BEHAVIOR OF CARBOHYDRATE MOLECULES IN SOLUTION ... 

Variable-temperature 13C NMR spin-lattice relaxation time measurements have been used to probe the motional behavior of 2,3 5,6-di-O-isopropylidene-a-D-mannofuranose (22) in dimethyl sulfoxide solution.67 This carbohydrate deriva-... 

A complementary article by Dais (Iraklion, Crete) addresses the theoretical principles underlying the phenomenon of carbon-13 nuclear magnetic relaxation, encompassing spin-lattice (Tt) and spin-spin (T2) relaxation times, the nuclear Overhauser enhancement, and their relation to the motional behavior of carbohydrates in solution. With examples broadly selected from simple sugar derivatives, oligosaccharides, and polysaccharides, the author shows how qualitative treatments have provided useful interpretations of the gross mobility of molecules in solution, but demonstrates how a quantitative approach may be of greater ultimate value. 

Muller and co-workers (02JPC(B)7781) investigated the molecular behavior of perdeuterated 1,3,5-trioxane in a cyclophosphazene inclusion compound by dynamic 2D NMR spectroscopy. The experimental data revealed a relatively complex motional behavior (rotational motion around the C3 axis of the molecule and around the channel long axis) in the phosphazene host channels the ring inversion process was almost uneffected by the host lattice and activation barriers, as reported from solution NMR studies (90JPC8845), were derived. 

Most studies of magnetic relaxation in polymers have dealt with solid or melted polymers (73)] however, Odajima (20) has studied proton relaxation in solutions of polystyrene and polyisobutylene. It is desirable to extend and refine such measurements. In concentrated solution, some insight into the motional effects of polymer-solvent interactions should be obtainable and if, despite low sensitivity, reliable 7 values can be obtained for polymers in dilute solutions, valuable information concerning the detailed motional behavior of isolated polymer molecules may be provided. 

Sampling Procedures The purpose of taking samples is to record the properties of the whole volume of material from a small, analyzed portion of it. This is difficult to achieve with solids since industrial mixes in particular always present a distribution of grain sizes, shape, or density and can also separate out when samples are being taken, on account of the ingredients specific motional behavior (see the subsection Sampling ). 

In general the labeled compound is an analog of a compound found naturally in the membrane system, and thus it is assumed that the motional behavior of the labeled species is very similar to that of its analog. It is surprising, therefore, that the surface properties of the spin labeled compounds have not been studied as extensively as those of the unlabeled... 

The spectral characteristics of the 612 monolayer indicate that the molecules are colliding much less frequently, and the apparent lack of hyperfine collapse indicates that the time between effective collisions is long on the ESR time scale. The problem to be considered, then, is how two systems can show such similar classical surface behavior and such dissimilar motional behavior. 

Molecular dynamics aims to reproduce the time-dependent motional behavior of a molecule. The method has been detailed at length in a number of reviews. 

The equivalent spherical particle diameter of an aggregate of irregularly shaped particles can be found by studying the inertial motion of particles in a medium. This inertial motion behavior is used in many applications, such as sedimentation vessels, electrostatic separators and precipitators, and particle collectors. The various forces that affect particle motion, shown in Figure 4, are briefly discussed below. 

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