Mode coupling corrections tot he Onsager coefficient as determined by light scattering of critical concentration fluctuations from polymer mixtures

2007 ◽  
pp. 66-68
Author(s):  
G. Meier ◽  
B. Momper ◽  
E. W. Fischer
Keyword(s):  
Light Scattering ◽  
Mode Coupling ◽  
Critical Concentration ◽  
Concentration Fluctuations ◽  
Polymer Mixtures

Light Scattering from Gels

1989 ◽  
Vol 62 (3) ◽  
pp. 498-514 ◽  
Author(s):  
G. D. Patterson
Keyword(s):  
Light Scattering ◽  
Poisson Ratio ◽  
Critical Concentration ◽  
Polymer Concentration ◽  
Concentration Fluctuations ◽  
Experimental Techniques ◽  
Spatial Correlations ◽  
Basic Principles ◽  
Partial States

Abstract The basic principles necessary to understand light scattering from gels are now well understood. The experimental techniques necessary to measure light scattering from gels are now highly developed. Yet there are many issues that need to be clarified in practice. The spatial correlations that exist in the polymer concentration in a gel need extensive further study. Gel samples with only intrinsic permanent concentration fluctuations need to be prepared. Defects due to dust, microsyneresis or other nonintrinsic inhomogeneities must be eliminated. Then careful measurements of R(q) should yield the necessary information about the microstructure of the gel. The value of the osmotic Poisson ratio is now well understood for gels at rest. Further work needs to be done on samples in partial states of swelling. More work appears promising in the study of critical concentration fluctuations in gels as well.

scholarly journals The effect of heavy chain phosphorylation and solution conditions on the assembly of Acanthamoeba myosin-II.

1989 ◽  
Vol 109 (4) ◽  
pp. 1529-1535 ◽  
Author(s):  
J H Sinard ◽  
T D Pollard
Keyword(s):  
Light Scattering ◽  
Ionic Strength ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Critical Concentration ◽  
Myosin Ii ◽  
Acidic Ph ◽  
Thick Filaments ◽  
Low Ionic Strength

At low ionic strength, Acanthamoeba myosin-II polymerizes into bipolar minifilaments, consisting of eight molecules, that scatter about three times as much light as monomers. With this light scattering assay, we show that the critical concentration for assembly in 50-mM KCl is less than 5 nM. Phosphorylation of the myosin heavy chain over the range of 0.7 to 3.7 P per molecule has no effect on its KCl dependent assembly properties: the structure of the filaments, the extent of assembly, and the critical concentration for assembly are the same. Sucrose at a concentration above a few percent inhibits polymerization. Millimolar concentrations of MgCl2 induce the lateral aggregation of fully formed minifilaments into thick filaments. Compared with dephosphorylated minifilaments, minifilaments of phosphorylated myosin have a lower tendency to aggregate laterally and require higher concentrations of MgCl2 for maximal light scattering. Acidic pH also induces lateral aggregation, whereas basic pH leads to depolymerization of the myosin-II minifilaments. Under polymerizing conditions, millimolar concentrations of ATP only slightly decrease the light scattering of either phosphorylated or dephosphorylated myosin-II. Barring further modulation of assembly by unknown proteins, both phosphorylated and dephosphorylated myosin-II are expected to be in the form of minifilaments under the ionic conditions existing within Acanthamoeba.

Mutual diffusion in binary polymer mixtures as measured by dynamic light scattering

1987 ◽  
Vol 86 (9) ◽  
pp. 5174-5181 ◽  
Author(s):  
M. G. Brereton ◽  
E. W. Fischer ◽  
G. Fytas ◽  
U. Murschall
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Mutual Diffusion ◽  
Polymer Mixtures ◽  
Binary Polymer

scholarly journals PECULARITIES OF MICELLE FORMATION OF PENTACYCLIC GLYCOSIDES IN AQUEOUS SOLUTIONS

2021 ◽  
Vol 64 (4) ◽  
pp. 26-33
Author(s):  
Natalia V. Mironenko ◽  
Irina V. Shkutina ◽  
Vladimir F. Selemenev
Keyword(s):  
Surface Tension ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Aqueous Solutions ◽  
Hydrodynamic Radius ◽  
Critical Concentration ◽  
Micelle Formation ◽  
Cylindrical Shape ◽  
Scattering Method ◽  
Dynamic Light Scattering Method

The regularities of changes in structural characteristics during the formation of associates in micellar aqueous solutions of triterpene saponins Quillaja Saponin and Sapindus Mukorossi are considered. The dependence of surface tension and adsorption on the concentration of an aqueous saponin solution is analyzed, and the values of surface activity and parameters of the adsorption layer are calculated. The average values of diffusion coefficients for spherical and cylindrical micelles are determined based on the measurement of the solution viscosity. The effect of the electrolyte solution on the surface tension and viscosity of glycoside solutions is studied: when the electrolyte is introduced into the saponin solution, the surface tension decreases, which leads to a shift in the critical concentration of micelle formation towards lower concentrations. The introduction of potassium chloride electrolyte reduces the degree of ionization and, as a result of suppressing the electroviscosity effect, leads to a decrease in the viscosity of the solution. The dynamic light scattering method is used to determine the size of glycoside aggregates. It is established that there are aggregates of several sizes in an aqueous solution of saponin. The size and shape of aggregates were calculated using the concepts of micelle packing parameters. In the region of very low concentrations of glycoside solutions, when approaching the critical concentration of micelle formation in the solution, there are spherical micelles. A further increase in the saponin concentration in the solution leads to a decrease in the content of structures with a hydrodynamic radius of 50-80 nm and the appearance of larger agglomerates with sizes greater than 100 nm. It was found that micelles acquire a less hydrated and more densely packed cylindrical shape in the concentration range of 1.7-2.6 mmol/dm3. Compaction of associates leads to an increase in the content of particles with a hydrodynamic radius of 150-250 nm and larger ones, and their presence predicts the appearance of larger agglomerates. Analyzing the data obtained using the dynamic light scattering method, it can be concluded that aggregates of several sizes co-exist in the volume of aqueous saponin solutions at certain concentrations.

Mode-coupling crossover in viscous toluene revealed by neutron and light scattering

1998 ◽  
Vol 1 (2) ◽  
pp. 169-172 ◽  
Author(s):  
J. Wuttke ◽  
M. Seidl ◽  
G. Hinze ◽  
A. Tölle ◽  
W. Petry ◽  
...  
Keyword(s):  
Light Scattering ◽  
Mode Coupling
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