THE MOLECULAR WEIGHT OF POLYVINYL ACETATE

1958 ◽  
Vol 36 (3) ◽  
pp. 543-549 ◽  
Author(s):  
A. F. Sirianni ◽  
R. Tremblay ◽  
I. E. Puddington
Keyword(s):  
Molecular Weight ◽  
Vapor Pressure ◽  
Polyvinyl Acetate ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Molecular Weights ◽  
Approximate Molecular Weight ◽  
Low Degrees ◽  
Made In

The molecular weights of a series of unfractionated polyvinyl acetates of low degrees of polymerization have been measured by determining the lowering of the vapor pressure of their solutions. An approximate molecular-weight range of 5000–40,000 was examined. While most of the determinations were made in benzene solutions at 55 °C., other solvents and temperatures were used. Anomalous results were obtained with one sample of fractionated material.

THE MOLECULAR WEIGHT OF POLYETHYLENE AND OF OTHER HIGH-MOLECULAR-WEIGHT ORGANIC COMPOUNDS

1958 ◽  
Vol 36 (5) ◽  
pp. 725-730 ◽  
Author(s):  
R. Tremblay ◽  
A. F. Sirianni ◽  
I. E. Puddington
Keyword(s):  
Molecular Weight ◽  
Vapor Pressure ◽  
High Molecular Weight ◽  
Organic Compounds ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Temperature Range ◽  
Molecular Weights ◽  
Pressure Lowering ◽  
Good Agreement

The temperature range of the measurement of vapor-pressure depression using a sensitive differential mercury micromanometer has been extended, and the behavior of a series of polyethylene samples having a molecular-weight range of 2500 to 24,000 was examined in toluene solutions at 75 °C. Good agreement was obtained between vapor-pressure lowering and other means of determining number-average molecular weights of several special compounds.

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.

scholarly journals The solubility of fibrinogen in solutions containing dextrans of various molecular weights (Short Communication)

1974 ◽  
Vol 143 (3) ◽  
pp. 767-769 ◽  
Author(s):  
Michael W. Rampling
Keyword(s):  
Molecular Weight ◽  
Short Communication ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Molecular Weights ◽  
Steric Exclusion

The effect of dextrans of various molecular weights on the solubility of fibrinogen was investigated. The results indicate that the prime effect responsible for the observed changes of solubility was steric exclusion. This applies over the whole molecular-weight range of dextrans used, i.e. from 5700 to 76000.

scholarly journals THE DETERMINATION OF MOLECULAR WEIGHT

1955 ◽  
Vol 33 (5) ◽  
pp. 755-762 ◽  
Author(s):  
A. F. Sirianni ◽  
I. E. Puddington
Keyword(s):  
Molecular Weight ◽  
Vapor Pressure ◽  
Organic Compounds ◽  
Chemical Stability ◽  
Pressure Difference ◽  
Molecular Weight Range ◽  
Vapor Pressure Difference ◽  
Static Measurement ◽  
Molecular Weights

The molecular weights of organic compounds of known constitution have been determined with satisfactory accuracy, using milligram quantities of materials, by a static measurement of the vapor pressure difference between pure solvents and solutions of the compounds. The method may be used over a considerable temperature range. The suitability of solvents is governed by their chemical stability and vapor pressure. Results obtained using compounds in the molecular weight range of 600–1000 are reported.

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

scholarly journals Difference in Thrombolytic Effect between Higher and Lower Molecular Weight Forms of Urokinase

1977 ◽  
Author(s):  
T. Suyama ◽  
M. Nishida ◽  
Y. Iga ◽  
R. Naito
Keyword(s):  
Molecular Weight ◽  
Gel Filtration ◽  
Lower Molecular Weight ◽  
Dissolution Time ◽  
Thrombolytic Activity ◽  
Lysis Time ◽  
Thrombolytic Effect ◽  
Approximate Molecular Weight ◽  
Made In

Urokinase (UK) from human urine has been widely used for thrombolytic therapy in Japan. However, commercially available preparations are not identical but consist of mainly two forms of UK with higher and lower molecular weight (H-UK and L-UK) . An attempt was made in this report to compare thrombolytic activity of H-UK with that of L-UK on artificial thrombi produced from human blood by a modification of Chandler’s loop method, which was somehow comparable to the situation in vivo. Two active forms of UK were purified from crude preparation by gel filtration. The approximate molecular weight of the H-UK was 54,000 and of the L-UK 34,000. The potency of UK was determined by “two-stage lysis time method” and expressed by International unit(lU). Thrombolytic activity measured by Chandler’s method was calculated as % lysis of the control thrombus that was formed in the abscence of UK.As a result, thrombus-dissolution time of H-UK was much shorter than that of L-UK. Furthermore, concentration of H-UK (IU/ml blood) necessary to induce 50% lysis was approximately one half lower than that of L-UK. The similiar results were obtained on artificial thrombi from the blood of dog, rat and rabbit. The data suggest that H-UK seems to be more effective on treatment of thromboembolicdisorders as compared to L-UK in terms of the same IU basis.

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.

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