Electro-optical studies of macromolecular solutions
Electro-optical studies of macromolecular solutions
The phenomenon known as the Kerr effect may be used to study the geometry and electro-optical characteristics of large molecules. These are manifest in the molecular relaxation time L and birefringence A n. The relevant theory when pulsed alternating and rectangular fields are applied to macromolecular solutions is reviewed and an apparatus suitable for such studies is described. Alternating fields in the frequency range 30 Hz to 30KHz and rectangular pulses of 2.5 BAs duration, giving field strengths up to 32 KV cm-1 * and of o-0-QS duration and 2400 v cm 7l are employed. The performance and method of use of the apparatus is described. Results are given for calf thymus and herring sperm DNA and the effects of 1-ray irradiation on both DNA and Bovine Serum Albumin (BSA) were investigated.It was found that the electric field strength and pulse duration influenced the values of the measured relaxation times of polydisperse samples of DNA. The interpretation of these results to get correct values of molecular lengths is discussed. A DNA molecule was found to is be somewhat flexible, but with a certain proportion of its length 4 rigid. IIII The latter was shown to be greatly affected by environment. It was found that I and A n exhibited maxima on variation of temperature and DNA concentration. It is inferred, therefore, that at low DNA concentration and An will also show maxima on variation of ion atmosphere concentration. The molecules were found to possess large dipole moments (1.5 x 105 Deby'e) along their major axes. This permanent-moment could be due to the presence of impurities attached to the DNA molecules, since it was found that mercaptoethanol reduced A n and'C.a Irradiation degraded DNA molecules and. caused BSA to form flexible aggregate whose size was calculated assuming a suitable model.
University of Southampton
1977
Almudafar, A.M.H
(1977)
Electro-optical studies of macromolecular solutions.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The phenomenon known as the Kerr effect may be used to study the geometry and electro-optical characteristics of large molecules. These are manifest in the molecular relaxation time L and birefringence A n. The relevant theory when pulsed alternating and rectangular fields are applied to macromolecular solutions is reviewed and an apparatus suitable for such studies is described. Alternating fields in the frequency range 30 Hz to 30KHz and rectangular pulses of 2.5 BAs duration, giving field strengths up to 32 KV cm-1 * and of o-0-QS duration and 2400 v cm 7l are employed. The performance and method of use of the apparatus is described. Results are given for calf thymus and herring sperm DNA and the effects of 1-ray irradiation on both DNA and Bovine Serum Albumin (BSA) were investigated.It was found that the electric field strength and pulse duration influenced the values of the measured relaxation times of polydisperse samples of DNA. The interpretation of these results to get correct values of molecular lengths is discussed. A DNA molecule was found to is be somewhat flexible, but with a certain proportion of its length 4 rigid. IIII The latter was shown to be greatly affected by environment. It was found that I and A n exhibited maxima on variation of temperature and DNA concentration. It is inferred, therefore, that at low DNA concentration and An will also show maxima on variation of ion atmosphere concentration. The molecules were found to possess large dipole moments (1.5 x 105 Deby'e) along their major axes. This permanent-moment could be due to the presence of impurities attached to the DNA molecules, since it was found that mercaptoethanol reduced A n and'C.a Irradiation degraded DNA molecules and. caused BSA to form flexible aggregate whose size was calculated assuming a suitable model.
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Published date: 1977
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Local EPrints ID: 462587
URI: http://eprints.soton.ac.uk/id/eprint/462587
PURE UUID: 669cf7df-ffc5-403b-bc0d-f9c016e187eb
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Date deposited: 04 Jul 2022 19:27
Last modified: 04 Jul 2022 19:27
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Author:
A.M.H Almudafar
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