scholarly journals Molecular weights and hydrodynamic properties for homogeneous native DNA, derived from diffusion, sedimentation, and viscosity measurements on polydisperse samples

Biopolymers ◽  
1971 ◽  
Vol 10 (9) ◽  
pp. 1735-1735
Author(s):  
K. E. Reinert ◽  
J. Strassburger ◽  
H. Triebel
Keyword(s):  
Hydrodynamic Properties ◽  
Viscosity Measurements ◽  
Molecular Weights

MOLECULAR WEIGHT AND HYDRODYNAMIC PROPERTIES OF SODIUM ALGINATE

1954 ◽  
Vol 32 (3) ◽  
pp. 227-239 ◽  
Author(s):  
W. H. Cook ◽  
David B. Smith
Keyword(s):  
Molecular Weight ◽  
Sodium Alginate ◽  
Intrinsic Viscosity ◽  
Diffusion Coefficients ◽  
Linear Relation ◽  
Hydrodynamic Properties ◽  
Viscosity Measurements ◽  
Molecular Weights ◽  
Extension Ratio ◽  
Good Agreement

Sedimentation, diffusion, and viscosity measurements were made on five unfractionated samples of sodium alginate ranging in intrinsic viscosity from 3.1 to 17.5. Diffusion coefficients were subject to large errors and are believed to be overestimated.Though the molecular weights obtained from sedimentation–diffusion (Svedberg equation) and sedimentation – intrinsic viscosity (Perrin–Simha equations) showed good agreement and yielded values of 3 to 21 × 104, higher values (4.6 to 37 × 104) from sedimentation–viscosity (Mandelkern–Flory equation) appear to be the better estimates. A linear relation between intrinsic viscosity and molecular weight was found with a slope (Mandelkern–Flory equation values) equivalent to Km = 13.9 × 10−3. The results indicate that sodium alginate has a relatively high extension ratio.

MOLECULAR WEIGHT AND HYDRODYNAMIC PROPERTIES OF SODIUM ALGINATE

1954 ◽  
Vol 32 (1) ◽  
pp. 227-239 ◽  
Author(s):  
W. H. Cook ◽  
David B. Smith
Keyword(s):  
Molecular Weight ◽  
Sodium Alginate ◽  
Intrinsic Viscosity ◽  
Diffusion Coefficients ◽  
Linear Relation ◽  
Hydrodynamic Properties ◽  
Viscosity Measurements ◽  
Molecular Weights ◽  
Extension Ratio ◽  
Good Agreement

Sedimentation, diffusion, and viscosity measurements were made on five unfractionated samples of sodium alginate ranging in intrinsic viscosity from 3.1 to 17.5. Diffusion coefficients were subject to large errors and are believed to be overestimated.Though the molecular weights obtained from sedimentation–diffusion (Svedberg equation) and sedimentation – intrinsic viscosity (Perrin–Simha equations) showed good agreement and yielded values of 3 to 21 × 104, higher values (4.6 to 37 × 104) from sedimentation–viscosity (Mandelkern–Flory equation) appear to be the better estimates. A linear relation between intrinsic viscosity and molecular weight was found with a slope (Mandelkern–Flory equation values) equivalent to Km = 13.9 × 10−3. The results indicate that sodium alginate has a relatively high extension ratio.

Propriétés hydrodynamiques des conformations ordonnées et desordonnées du poly(γ-L-glutamate de benzyle): dimensions et flexibilité de la chaîne

1978 ◽  
Vol 56 (11) ◽  
pp. 1569-1574
Author(s):  
Nga Ho-Duc
Keyword(s):  
Quantitative Agreement ◽  
Dichloroacetic Acid ◽  
Random Coil ◽  
Hydrodynamic Properties ◽  
Molecular Weights ◽  
Coil Transition ◽  
Rigid Segment ◽  
Good Agreement ◽  
Stiff Chain

Theoretically we can determine the disordered or ordered structure of polypeptides and their dimensions in dilute solutions from hydrodynamic properties. We have presently a wealth of theories for random coil chains and a limited but sufficient number of theories for ordered chains for interpreting experimental results.Viscosity data for seven poly(γ-benzyl-L-glutamate) samples in 1,2-dichloroethane at 25 °C are analyzed and the length per monomeric residue (h) is calculated according to the equivalent ellipsoid approach. The degree of flexibility or rigidity is characterized by calculating Ns, the number of monomer units in a rigid segment or a Kuhn statistical segment; the determination of Ns is made by applying Yamakawa and Fujii's equation modified by Vitovskaya and Tsvetkov.Values obtained for h assuming the solute molecule to be a rigid, stiff chain, range between 1.3 to 2 Å. One notices that the h value close to 1.5 Å is found for the three following molecular weights: 1.8 × 105, 1.7 × 105, and 1.5 × 105. They are, in fact, the samples having a length in good quantitative agreement with that of the rigid segment determined by the method of Vitovskaya and Tsvetkov. This rigid segment corresponds to a sample of 700 ± 100 monomer units.The analysis of the experimental data of poly(γ-benzyl-L-glutamate) in dichloroacetic acid indicates that, in addition to the formation of hydrogen bonds, other interactions between the polypeptide and the solvent are present.In summary, we may conclude that the study of the helix–coil transition using hydrodynamic measurements is judged satisfactory but the determination of characteristic dimensions used to describe exactly the conformation of the macromolecule is somewhat ambiguous. One major problem is the degree of flexibility encountered with high molecular weight chains. However, to get around this difficulty, we propose, according to our results, a method which consists in determining the number of monomer units within a rigid segment from the different values found for h and then the dimensions from the samples for which the chain length is in good agreement with that of a rigid segment thus determined.

Isoprene and Rubber. Part 44. Viscosity Measurements of Squalene and Hydrosqualene Solutions

1936 ◽  
Vol 9 (4) ◽  
pp. 573-578
Author(s):  
H. Staudinger ◽  
H. P. Mojen
Keyword(s):  
Physical Properties ◽  
General Relation ◽  
Basic Structure ◽  
Degree Of Polymerization ◽  
Specific Viscosity ◽  
Viscosity Measurements ◽  
Molecular Weights ◽  
Gutta Percha ◽  
Rubber Part

Abstract The physical properties of highly polymerized substances, which are composed of fiber molecules, depend on the lengths of the chains of these fiber molecules. Thus tensile strength, elasticity, tendency to swell in solvents, and above all viscosity, are dependent on the length of chain of the particular substance. Among the substances, the properties of which vary thus, are rubber, gutta-percha, and balata. Since the length of fiber molecules can vary within wide limits, such physical properties as those mentioned above show wide variations in the case of rubber, gutta-percha, and balata. This is evident for example by a comparison of the properties of unmasticated rubber, which consists of long fiber molecules of a degree of polymerization of 2000, with the properties of masticated rubber, the greatly dissociated molecules of which have a degree of polymerization of only 500. The determination of the length of the fiber molecules is therefore of great importance in the case of highly polymerized substances. It has already been proved in past experiments with members of a series of homologous polymers, i. e., of substances the macromolecules of which have the same basic structure and differ only in length, that the molecular weights can be determined from viscosity measurements. This determination is based on the fact that there is a general relation between the specific viscosity and the length of the dissolved molecules, which can be expressed by the formula:

An Investigation of the Viscosity of Rubber Solutions

1930 ◽  
Vol 3 (4) ◽  
pp. 604-611 ◽  
Author(s):  
C. M. Blow
Keyword(s):  
Molecular Weight ◽  
Mechanical Treatment ◽  
Viscosity Coefficient ◽  
Dilute Solutions ◽  
Viscosity Measurements ◽  
Molecular Weights

Abstract Viscosity measurements have frequently been made with rubber, and very many suggestions have been put forward to explain the cause of the changes of viscosity in rubber solutions. According to Staudinger (Kautschuk, 5, 128 (1929)), if measured under certain conditions, e. g., in dilute solutions where no irregularities are found, the viscosity can be used as a measure of the molecular weight of the dissolved substance. Fickentscher and Mark (Kolloid-Z., 49, 140 (1929)) even calculate from viscosity measurements the length of the molecule and hence relative molecular weights. It is well known that the viscosities of rubber solutions differ greatly and that mechanical treatment of the rubber decreases the viscosity of its solutions to a very large extent. The latter effect has been explained by Staudinger as well as by Fickentscher and Mark (loc. cit.) as a depolymerization. The latter authors calculate that the molecular weight of rubber decreases to one-third of the original if it is masticated for 225 minutes. It has further been pointed out recently by Herschel and Bulkley (Kolloid-Z., 39, 291 (1926)) that rubber solutions show irregularities in their viscosity, e. g., the viscosity is not linearly proportional to the pressure. (According to Poiseuille's formula for the rate of flow of a liquid through a capillary, the viscosity coefficient:

scholarly journals The Molecular Weights of Protamines by means of Diffusion and Viscosity Measurements.

1954 ◽  
Vol 75 (3) ◽  
pp. 342-346 ◽  
Author(s):  
Koujirou Iso ◽  
Tomoko Kitamura ◽  
Itaru Watanabe
Keyword(s):  
Viscosity Measurements ◽  
Molecular Weights

Isoprene and Rubber. Part 34. Molecules or Micelles in a Rubber Solution

1932 ◽  
Vol 5 (3) ◽  
pp. 265-277
Author(s):  
H. Staudinger ◽  
H. F. Bondy
Keyword(s):  
Colloidal Solutions ◽  
Dilute Solutions ◽  
Pure Nitrogen ◽  
Viscosity Measurements ◽  
Molecular Weights ◽  
Colloid Particles ◽  
Rubber Part ◽  
Complete Exclusion ◽  
The Individual ◽  
Viscous Solutions

Abstract Measurements of the Viscosity of Rubber Solutions In the literature may be found numerous measurements of the viscosity of rubber solutions, the object of which was to throw light on the nature of colloidal solutions and changes in these solutions by various operations. These investigations give no insight into the structure of colloid particles and the reason for changes in rubber solutions because they are based on false assumptions, particularly the assumption that rubber has a micellar structure. Often highly viscous solutions were studied, and though these appeared to be of special interest to the colloid chemist, they were unsuited for such investigations, for they are gel solutions in which the structure of the colloid particles is much more difficult to explain than is that in dilute solutions (sol solutions), where the molecules have freedom of movement and do not disturb one another. The earlier works also contain references to the sensitivity of rubber to oxygen, though no special precautions were ever taken in the measurements to exclude oxygen; in fact this was unnecessary as a rule, for crude rubber solutions are much more stable, because of anticatalysts present, than solutions of pure rubber in which these have been removed. Pure rubber was prepared by the method of Pummerer and Pahl and, as described in the following work, was separated by fractional extraction into portions of different average molecular weights. Viscosity measurements of the individual fractions were then carried out under various conditions. The study of the rubber solution, like that of the balata solution, must be carried out with complete exclusion of air, and the solvent (tetralin or benzene) must be distilled in an atmosphere of pure nitrogen and be freed of oxygen. The filtration of the rubber solution, the filling of the viscosimeter, as well as the measurements themselves, are likewise made in an atmosphere of pure nitrogen. Measurements were taken in the Ubbelohde viscosimeter at different pressures, as a rule at 10.30 and 60 cm. mercury pressure. Very dilute solutions were also measured in the Ostwald viscosimeter, since the deviations from the Hagen-Poiseuille law are of no great importance at low concentration. Finally, it should be mentioned that these special precautions during the viscosity measurements, above all the careful exclusion of air, are necessary only in the case of rubber, not with the saturated hydrocarbons, polystyrene, and hydrorubber.

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