Correlation times physical content

D. J. Tannor One would think that as one adds more and more layers of solvent one is introducing irreversible decay of the correlation function of the solute-solvent coupling. The main physical content of the Grote-Hynes expression for the rate constant is that contributions from this correlation function that are slow compared with the time scale for reaction do not really contribute to the reaction rate. This suggests that by starting with a description of only the first solvent shell and introducing shorter and shorter solvent memory, one will see a transition that resembles that of adding more and more solvent shells. 

TMD). All mixts followed the physical model proposed for DDT of 91/9 RDX/wax. However, the series run at fixed % TMD and varying wax content showed strong correlations between the relative time to deton and the predetonation column length. No similar correlation appears at fixed compn and varying porosity... 

Two areas of research, psychophysics and sensory evaluation, have made recent contributions to the understanding of oral sensations of heat derived from peppers. Psychophysical studies have characterized observer s responses to heat from spice-derived compounds, focussing on such aspects as time-intensity functions, areas of oral stimulation, correlation with evoked salivary flow, interactions with basic tastes, and effects of sequential stimulation. Sensory evaluation of the heat level of ground red pepper has recently been advanced by the validation of a new method which solves many of the problems inherent in the previous Scoville procedure. The new method is based on anchored graphic rating by panels Who are trained with physical reference standards. The procedure has shown excellent reliability, fine discriminations among samples, and high correlations with instrumental determinations of capsaicinoid content of pepper samples. 

The phenomenon of fluorescence can provide information about the physical properties of proteins and other macromolecules. The information content results from the sensitivity of the spectral properties to the average and dynamic properties of the environment surrounding the fluorescent residues. In general, more detailed information is obtainable from time-resolved data than from steady-state measurements. However, the steady-state measurements are considerably easier to perform. At present, the ability to recover time-resolved spectral data is rapidly improving, primarily because of advances in instrument design. The newer instruments may possess resolution adequate to correlate experimental data with the structural or dynamic properties of macromolecules. 

The drawback to this approach is relating the time domain information to a chemical species or physical phenomena. Many broadline systems are used in an empirical fashion in which the results are correlated with a process control parameter or measured physical property. However, this approach alone does not indicate which chemical species is being measured. The signals could be due to water or fat content, bound water versus free water in a slurry or different phases of a polymer, crystalline, amorphous or interfacial regions. To ensure that these correlations are due to specific chemical species broadline NMR data must be related to some other primary analytical technique such as high resolution NMR. 

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