Scaling parameters probe size

Figure 3.15 Scaling parameters a and v from fits of p c) to stretched exponentials in c, plotted as a function of the probe size. The matrix polymers as shown above were ( ) 100 kDa hydroxyethylcellulose(5), and ( ) 100, (0) 300, and (A) 1000 kDa hydroxypropylcellulose, and ( ) 1000 and (O) H O kDa linear polyacrylamide(6).

While multimodal probe spectra have been reported in several systems, only for hydroxypropylcellulose water has there been a thorough examination of multiple experimental parameters. This examination demonstrated the presence of a variety of phenomena that only became apparent because an extremely thorough study was done of the consequences of changing the probe size and the matrix concentration. For example, probe and probe-free HPC solution spectra are both bimodal or both trimodal, and have modes on the same time scales. However, the probe and polymer modes are not the same they have opposing concentration dependences. 

Figure 7.3 Sketch of a protoplanetary disk surrounding a solar-type star showing the regions in which different techniques probe grain and particle sizes. More luminous stars, like Herbig Ae-type stars, will stretch the scale by up to a factor of 10, while less luminous stars, like brown dwarfs, will shrink it by a comparable factor. See Table 8.1 for stellar parameters of young stars.

Astrophysical measurements enable us to probe the variation of the fundamental constants. The energy scale of atomic spectra is given by the atomic unit me /h . In the non-relativistic limit, aU atomic spectra are proportional to this constant and analyses of quasar spectra cannot detect any change of the fundamental constants. Indeed, any change in the atomic unit wiU be absorbed in the determination of the redshift parameter z (1 - - z = w/w, lj is the redshifted frequency of the atomic transition and w is the laboratory value). However, any change in the fundamental constants can be found by measuring the relative size of relativistic corrections, which are proportional to. ... 

Spectroscopic Methods.—Nuclear Magnetic Resonance (n.m.r.). Cohen-Addad and Ruby comment that thermodynamic polymer-solvent interaction parameters obtained from n.m.r. data should be contrasted with those obtained from other methods in the sense that the former are defined on a molecular scale only. That is, nuclear spins are local probes, sensitive to magnetic interactions averaged over volumes of molecular size. N.m.r. methods, therefore, usefully complement other methods in studying underlying statistical mechanical models for polymer-solvent mixtures at equilibrium a comment which has been amplified in relation to polymer blends. ... 

A microelectrode is an essential element in an SECM. Precisely, the microelectrode is the probe with which the surface of the sample is scanned. The lateral resolution of the SECM is determined by the size of the scanning probe. Therefore, micro-electrodes of small dimensions are necessary to obtain laterally highly resolved images. Decreasing the size of the electrode from macro- to micro-scale brings additional features to the electrode behavior. The special properties of microelectrodes are very important not only to their application in SECM. The small size of a microelectrode influences two key parameters (i) the mass transport of species and (ii) the current line distribution. 

This section considers true microrheological measurements in which external forces or displacements are imposed, and consequent displacements or forces are measured. True microrheological measurements, not to be confused with microrheology studies of Brownian motion, differ from classical macroscopic measurements only in that the apparatus functions on a mesoscopic length scale. It becomes interesting to compare viscoelastic parameters from classical instruments, parameters measured with true microrheological instruments built on the size scale of diffusing probes, and parameters inferred from the diffusion of those particles. 

Extended analysis of all spectral parameters for hydroxypropylcellulose solutions, in particular the relative behavior of smaller and larger probe particles, impUes that these solutions are characterized by a single, concentration-independent, length scale that is approximately the size of a polymer coil. This scale is significantly... 

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