Fight scattering

The translational diffusion coefficient in Eq. 11 can in principle be measured from boimdary spreading as manifested for example in the width of the g (s) profiles although for monodisperse proteins this works well, for polysaccharides interpretation is seriously complicated by broadening through polydispersity. Instead special cells can be used which allow for the formation of an artificial boundary whose diffusion can be recorded with time at low speed ( 3000 rev/min). This procedure has been successfully employed for example in a recent study on heparin fractions [5]. Dynamic fight scattering has been used as a popular alternative, and a good demonstra-... 

Equation (6.12) is important it shows that we can determine the relative molar mass of the molecule from the experimental measurement of the Rayleigh ratio in fight scattering. 

The liglit-scattering principle of cell court dug is based on the observadon that microscopic particles, such as blood cells, scatter into small (0 15°) angles, most of the visible light incident upon them. This principle is used to count red blood cells, white blood cells, and platelets. In the basic form of the fight-scattering method, a dilute suspension of cells and a sheathing... 

One optical imaging technique that circumvents the problem of multiple fight scattering is to estimate the bubble size distribution from the area individual foam bubbles occupy ai a glass surface. Such experiments, and the systematic differences between bulk and surface bubble distributions, have been reviewed. Another technique that also directly measures the bubble size distribution is ihe use Of a Coulter counter, where individual bubbles are drawn through a small lube and counted. This yields a direct measure of the bubble size distribution, hut it is invasive and cannot probe the structure of the foam. 

Concerning aggregation kinetics and stabilization it was found in case of barium sulfate that barium ions adsorb more readily than sulfate ions [11], Thus, increasing the ratio R of barium to sulfate ions in the educt composition and thereby increasing the excess of barium ions after precipitation leads to high surface potentials and stabilization. Fig. 5 shows measured particle size distributions of continuously precipitated barium sulfate, measured based on quasi-elastic fight scattering (UPA 150 by Microtrac) within 3 min after pie-... 

In principle, intrachain contraction should occur before interchain association as long as the solution is sufficiently dilute. The limitation is the sensitivity of our detection in laser fight scattering. Note that in Fig. 27,... 

Other techniques, such as fight scattering and sedimentation, are also sensitive to particle shape. The direct observation of particles by a scanning electron microscope and distribution measurements by image analysis would appear to overcome many of the problems associated with the various other techniques, but problems of describing irregularly shaped particles remain. A universal particle size descriptor has not yet been developed. The technique adopted and the results obtained are most useful when empirical correlations with the end use can be made. 

Muller et al. [53] prepared similar PMMA-g-PMMA by radical copolymerization of MMA with methacrylate-terminated PMMA macromonomer, 29, and characterized the samples by SEC-multiangle laser fight scattering (MALLS). The power law exponent, a, in the equation, 1/2°cMa, was found to be 0.36. In remarkable contrast to the result of Ward et al. [51], the shrinking factor decreased with increase of MW. This may imply that the difference in graft copolymerization method, anionic or radical, results in the graft copolymers with very different branch distribution. 

MALLS multiple angle laser fight scattering... 

That no indication of the significant influence of particle shape on FFF elution behavior has been published until recently may be attributed to the fact that the majority of the approximately 500 papers so far published have reported on spherical or nearly spherical samples, and that the studies on the non-spherical samples focused only on sample fractionation rather than on a quantitative assessment of physicochemical quantities. This problem can be solved if fractions from FFF are further characterized, for example, by dynamic fight scattering or if an independent detector for diffusion coefficients is available. 

Laser fight scattering was described by one of us (2) for measuring the phase structure of an MBAS plastic as a function of graft rubber concentration. The data were analyzed with the Debye-Bueche expression (I, 2)... 

A species of interest needs to be either soluble or solubilized in an inert, transparent, isotropic and non fight-scattering medium. 

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