Solution Properties of Poly(n-butyl isocyanate). 1. Characterization and Intrinsic Viscosity Behavior Over an Extended Molecular Weight Range

1978 ◽  
Vol 11 (2) ◽  
pp. 300-306 ◽  
Author(s):  
M. R. Ambler ◽  
D. McIntyre ◽  
L. J. Fetters
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Solution Properties ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Viscosity Behavior

scholarly journals Nuclear matrix of HeLa S3 cells. Polypeptide composition during adenovirus infection and in phases of the cell cycle.

1977 ◽  
Vol 72 (1) ◽  
pp. 194-208 ◽  
Author(s):  
L D Hodge ◽  
P Mancini ◽  
F M Davis ◽  
P Heywood
Keyword(s):  
Cell Cycle ◽  
Molecular Weight ◽  
Nuclear Matrix ◽  
Apparent Molecular Weight ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Molecular Weights ◽  
Liver Nuclei ◽  
Hela S3 ◽  
Biochemical Analyses

A subnuclear fraction has been isolated from HeLa S3 nuclei after treatment with high salt buffer, deoxyribonuclease, and dithiothreitol. This fraction retains the approximate size and shape of nuclei and resembles the nuclear matrix recently isolated from rat liver nuclei. Ultrastructural and biochemical analyses indicate that this structure consists of nonmembranous elements as well as some membranous elements. Its chemical composition is 87% protein, 12% phospholipid, 1% DNA, and 0.1% RNA by weight. The protein constituents are resolved in SDS-polyacrylamide slab gels into 30-35 distinguishable bands in the apparent molecular weight range of 14,000 - 200,000 with major peptides at 14,000 - 18,000 and 45,000 - 75,000. Analysis of newly synthesized polypeptides by cylindrical gel electrophoresis reveals another cluster in the 90,000-130,000 molecular weight range. Infection with adenovirus results in an altered polypeptide profile. Additional polypeptides with apparent molecular weights of 21,000, 23,000, and 92,000 become major components by 22 h after infection. Concomitantly, some peptides in the 45,000-75,000 mol wt range become less prominent. In synchronized cells the relative staining capacity of the six bands in the 45,000-75,000 mol wt range changes during the cell cycle. Synthesis of at least some matrix polypeptides occures in all phases of the cell cycle, although there is decreased synthesis in late S/G2. In the absence of protein synthesis after cell division, at least some polypeptides in the 45,000-75,000 mol wt range survive nuclear dispersal and subsequent reformation during mitosis. The possible significance of this subnuclear structure with regard to structure-function relationships within the nucleus during virus replication and during the life cycle of the cell is discussed.

Structure and Solution Properties of High Molecular Weight Butadiene-Styrene Copolymers

1957 ◽  
Vol 30 (1) ◽  
pp. 315-325
Author(s):  
R. B. MacFarlane ◽  
L. A. McLeod
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Complex Structure ◽  
Mixed Solvents ◽  
Solution Time ◽  
Solution Viscosity ◽  
Solution Properties ◽  
Molecular Weight Range ◽  
Viscosity Measurements ◽  
Commercial Practice

Abstract Production of high molecular weight copolymers of butadiene and styrene for use in oil-extended rubbers has aroused interest in the solution properties of copolymers above the molecular weight range commonly encountered in commercial practice. It has been observed that solubility of such polymers in toluene is a time-dependent phenomenon and the apparent solubility can increase continuously, in the absence of agitation, for as long as 800 hours. Although a standard Harris cage solubility test may show the presence of 50% gel, other properties do not confirm the presence of any appreciable quantities of insoluble material. Mild agitation rapidly promotes almost complete solubility. Dilute solution viscosity measurements are very misleading unless the influence of solution time is recognized and apparent intrinsic viscosities rise progressively with time of contact of the sample with solvent. This time-dependence of solution has been found to occur at conversions higher than 50% and is also a function of the amount of modifier used in the polymerization recipe. It has not been possible to shorten the solution time for viscosity measurements by mild heating or gentle agitation. Mixed solvents cause a change in the amount of increase of the apparent intrinsic viscosity but do not shorten the time to equilibrium. Measurement of the slope constant in the Huggins viscosity equation indicate that these solubility and viscosity effects coincide with the appearance of a marked degree of branching in the polymer molecules. The effect is, therefore, interpreted as being caused by the relatively slow disentanglement of molecules of complex structure.

Uremic Neurotoxin in the Middle Molecular Weight Range

1980 ◽  
Vol 4 (2) ◽  
pp. 116-120 ◽  
Author(s):  
N.K. Man ◽  
G. Cueille ◽  
J. Zingraff ◽  
J. Boudet ◽  
A. Sausse ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Range ◽  
Weight Range

Aqueous polypropylene glycol induces swelling and severe plasticization of high Tg amphiphilic copolymers containing hexafluoroisopropanol groups

Soft Matter ◽  
2020 ◽  
Vol 16 (27) ◽  
pp. 6362-6370
Author(s):  
Siyuan Li ◽  
Bryan D. Vogt
Keyword(s):  
Molecular Weight ◽  
Propylene Glycol ◽  
Polypropylene Glycol ◽  
Amphiphilic Copolymers ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Poly Propylene

Not too big, not too small, but a narrow molecular weight range for poly(propylene glycol) where swelling of the copolymer increases tremendously for poly(propylene glycol).

Molecular Weights and Intrinsic Viscosities of Polyisobutylenes

1943 ◽  
Vol 16 (3) ◽  
pp. 493-508
Author(s):  
Paul J. Flory
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Average Molecular Weight ◽  
Chain Structure ◽  
Molecular Weight Range ◽  
Molecular Weights ◽  
Satisfactory Precision ◽  
Heterogeneous Polymers ◽  
Definition Of

Abstract Experimental methods for fractionating polyisobutylene and for determining osmotic pressures have been described. The ratio π/c of osmotic pressure to concentration has been found in the case of cyclohexane solutions of polyisobutylene to vary nonlinearly with concentration, contrary to recent theories advanced by Huggins and the writer. The slope of this relationship appears to be independent of molecular weight. Reliable methods for extrapolating π/c to c=0 have been established, enabling the determination of absolute molecular weights with satisfactory precision up to values of about 1,000,000. Molecular weights of polyisobutylenes calculated from Staudinger's equation are too low; the discrepancy is more than ten-fold at high molecular weights. On the basis of data for carefully fractionated samples covering a two-hundred-fold molecular weight range, the intrinsic viscosity is found to be proportional to the 0.64 power of the molecular weight. This decided deviation from Staudinger's “law”cannot in this instance be attributed to nonlinear chain structure, as Staudinger has sought to do in other cases. This dependence of molecular weight on intrinsic viscosity leads to the definition of a “viscosity average”molecular weight which is obtained when the relationship is applied to heterogeneous polymers. The viscosity average is less than the weight average molecular weight, which would be obtained if Staudinger's equation were applicable, and greater than the number average obtained by osmotic or cryoscopic methods.

Forces between poly-l-lysine of molecular weight range 4,000–75,000 adsorbed on mica surfaces

1987 ◽  
Vol 25 (2-4) ◽  
pp. 263-277 ◽  
Author(s):  
T. Afshar-rad ◽  
A.I. Bailey ◽  
P.F. Luckham ◽  
W. Macnaughtan ◽  
D. Chapman
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Range ◽  
Weight Range
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