Orientation of Polymer Coils in Dilute Solutions Undergoing Shear Flow: Birefringence and Light Scattering

1995 ◽  
Vol 28 (17) ◽  
pp. 5852-5860 ◽  
Author(s):  
Jacques Bossart ◽  
Hans Christian Oettinger
Keyword(s):  
Light Scattering ◽  
Shear Flow ◽  
Flow Birefringence ◽  
Dilute Solutions

Orientation of Polymer Coils in Dilute Solutions Undergoing Shear Flow:  Birefringence Experiments

1997 ◽  
Vol 30 (18) ◽  
pp. 5527-5540 ◽  
Author(s):  
Jacques Bossart ◽  
Hans Christian Öttinger
Keyword(s):  
Shear Flow ◽  
Flow Birefringence ◽  
Dilute Solutions

Kinetics of flowing dispersions. X. Oscillations in optical properties of streaming suspensions of spheroids

1977 ◽  
Vol 55 (24) ◽  
pp. 4243-4256 ◽  
Author(s):  
A. Okagawa ◽  
S. G. Mason
Keyword(s):  
Light Scattering ◽  
Shear Flow ◽  
General Pattern ◽  
Relaxation Times ◽  
Simple Shear Flow ◽  
Scattering Coefficients ◽  
Human Red Blood Cells ◽  
Dielectric Particles ◽  
Dilute Suspensions ◽  
Orientation Distributions

Transients in angular light scattering and turbidity of dilute suspensions of nearly monodisperse spheroidal particles undergoing simple shear flow have been investigated by combining Rayleigh–Debye light scattering theory for single dielectric particles with fluid mechanical theory for the orientation distributions of particle assemblies in shear flow. Applying shear to an initially isotropic suspension causes the orientation distributions and thus the angular scattering coefficients to oscillate. Various geometrical arrangements are considered with a view to selecting those that will maximize such rheo-optical effects.By calculating the optical scattering cross section of a single particle, the turbidity of a suspension is obtained; like the scattering coefficient, it undergoes oscillations that are damped by (1) the inevitable spread in particle shape and volume in real systems, (2) shear-induced particle interactions, and (3) rotary Brownian motion. The rates of damping, expressed as relaxation times, are considered for the three mechanisms acting alone or in concert.Preliminary measurements of the turbidity of dilute suspensions of hardened human red blood cells confirm this general pattern of behavior. Apart from their intrinsic interest, such rheo-optical effects can be used to determine a number of useful properties of dispersions.

Measurements of Light Scattering Intensities on Extremely Dilute Solutions of Nonionic Surfactant

Langmuir ◽  
1995 ◽  
Vol 11 (6) ◽  
pp. 1867-1869 ◽  
Author(s):  
Tadashi Kato ◽  
Masaki Kanada ◽  
Tsutomu Seimiya
Keyword(s):  
Light Scattering ◽  
Nonionic Surfactant ◽  
Dilute Solutions

Bifunctional Photobinding of Psoralen to Single Stranded Nucleic Acids

1973 ◽  
Vol 28 (7-8) ◽  
pp. 370-375 ◽  
Author(s):  
S Marciani ◽  
M. Terbojevich ◽  
F Dall 'Acqua ◽  
G. Rodighiero
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Nucleic Acids ◽  
Dilute Solutions ◽  
Base Pairs ◽  
Bacterial Dna ◽  
Disordered Structure ◽  
Concentrated Solution ◽  
Reduced Rate ◽  
Molecular Weight Of Dna

Abstract As psoralen and other furocoumarin derivatives, intercalated between two base pairs of native DNA, under irradiation at 365 nm form inter-strand cross-linkings as a consequence of bifunctional addition, the writers have investigated the ability of psoralen to give such bifunctional photo­ additions, too, with nucleic acids with disordered or partilly disordered structure (denatured DNA and r-RNA). On the basis of fluorimetric, light-scattering, viscosimetric measurements and of the renaturation ability of denatured bacterial DNA, certain results have been obtained. In addition to monofunctional photoadditions, psoralen can give bifunctional binding by irradiation at 365 nm both with denatured DNA and with r-RNA. However, when irradiation of denatured DNA in the presence of psoralen was performed in a concentrated solution (0.4%), the formation of bifunctional additions between two different strands was demonstrated by the increase (50%) of molecular weight of denatured DNA. However, when irradiation of denatured DNA was performed in more dilute solutions (0.1%), the bifunctional photoaddition of psoralen took place producing only bi­ functional additions in the same strand, very probably with the formation of loops, as has been shown by the absence of increase of molecular weight of DNA and by the more restricted structure assumed by the macromolecule, revealed by the light-scattering and viscosimetric measurements. The formation of these bifunctional additions was confirmed by the reduced rate of renaturation shown by denatured bacterial DNA after irradiation in the presence of psoralen. In the case of r-RNA, psoralen, when irradiated can form bifunctional additions only in the same strand.

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