scholarly journals Unexpected Molecular Weight Dependence to the Physical Aging of Thin Polystyrene Films Present at Ultra‐High Molecular Weights

2019 ◽  
Vol 57 (18) ◽  
pp. 1224-1238 ◽  
Author(s):  
Michael F. Thees ◽  
Connie B. Roth
Keyword(s):  
Molecular Weight ◽  
Physical Aging ◽  
Molecular Weights ◽  
Molecular Weight Dependence

Molecular Weight Effects in Adsorption of Rubbers on Carbon Black

1968 ◽  
Vol 41 (5) ◽  
pp. 1256-1270 ◽  
Author(s):  
Gerard Kraus ◽  
J. T. Gruver
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
Large Particle ◽  
Molecular Weights ◽  
Molecular Weight Dependence ◽  
Bound Rubber ◽  
Sieve Effect ◽  
High Structure ◽  
Very High ◽  
Poor Solvent

Abstract The molecular weight dependence of the adsorption of polybutadiene on carbon black from a poor solvent, n-heptane, and bulk, i.e., the phenomenon of “bound rubber”, was investigated. For narrow distribution polymers the adsorption is proportional to Mn, where n = 0.14 for adsorption from n-heptane solution; n = 0.5 for adsorption from bulk. Anomalously low solution adsorption was observed for polymers of very high molecular weight (> 500,000). This is ascribed to a sieve effect by aggregates of carbon black particles which cannot be penetrated by the large molecular coils. In high structure blacks, which pack more loosely, and in large particle blacks, which form larger interstices between particles, onset of anomalous adsorption is shifted toward higher molecular weights.

Molecular-weight dependence of the formation of highly ordered lamellar structures of poly(N-dodecyl acrylamide) by humid annealing

2019 ◽  
Vol 10 (7) ◽  
pp. 835-842 ◽  
Author(s):  
Kazuki Ebata ◽  
Yuki Hashimoto ◽  
Kohei Ebara ◽  
Mayu Tsukamoto ◽  
Shunsuke Yamamoto ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Main Chain ◽  
Side Chains ◽  
Molecular Weights ◽  
Lamellar Structures ◽  
Molecular Weight Dependence ◽  
Alkyl Side Chains

Highly oriented lamellar films of poly(N-dodecylacrylamide) with high molecular weights were formed by nanosegregation between alkyl side chains and a water-adsorbed main chain.

scholarly journals On the molecular-weight-dependence of the anticoagulant activity of heparin

1979 ◽  
Vol 181 (1) ◽  
pp. 241-243 ◽  
Author(s):  
L Thunberg ◽  
U Lindahl ◽  
A Tengblad ◽  
T C Laurent ◽  
C M Jackson
Keyword(s):  
Molecular Weight ◽  
Anticoagulant Activity ◽  
Factor Xa ◽  
Coagulation Factor ◽  
Molecular Weights ◽  
High Affinity ◽  
Polysaccharide Chain ◽  
Molecular Weight Dependence ◽  
Heparin Fractions

The inactivation of thrombin and factor Xa by antithrombin was determined in the presence of heparin fractions of different molecular weights and with high affinity for antithrombin. The ability to potentiate the inactivation of either coagulation factor increased with increasing length of the polysaccharide chain.

Molecular weight dependence of the physical aging of polycarbonate

Polymer ◽  
2019 ◽  
Vol 178 ◽  
pp. 121571
Author(s):  
Shotaro Nishitsuji ◽  
Yuki Watanabe ◽  
Hiroshi Ito ◽  
Masaru Ishikawa ◽  
Takashi Inoue ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Physical Aging ◽  
Molecular Weight Dependence

Investigation by HPLC of the Catabolism of Recombinant Tissue Plasminogen Activator in the Rat

1988 ◽  
Vol 60 (01) ◽  
pp. 107-112 ◽  
Author(s):  
Roy Harris ◽  
Louis Garcia Frade ◽  
Lesley J Creighton ◽  
Paul S Gascoine ◽  
Maher M Alexandroni ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Half Life ◽  
Recombinant Tissue Plasminogen Activator ◽  
Rat Plasma ◽  
High Molecular Weight Complex ◽  
Molecular Weights ◽  
Major Activity ◽  
Tissue Plasminogen

SummaryThe catabolism of recombinant tissue plasminogen activator (rt-PA) was investigated after injection of radiolabelled material into rats. Both Iodogen and Chloramine T iodination procedures yielded similar biological activity loss in the resultant labelled rt-PA and had half lives in the rat circulation of 1 and 3 min respectively. Complex formation of rt-PA was investigated by HPLC gel exclusion (TSK G3000 SW) fractionation of rat plasma samples taken 1-2 min after 125I-rt-PA injection. A series of radiolabelled complexes of varying molecular weights were found. However, 60% of the counts were associated with a single large molecular weight complex (350–500 kDa) which was undetectable by immunologically based assays (ELISA and BIA) and showed only low activity with a functional promoter-type t-PA assay. Two major activity peaks in the HPLC fractions were associated with Tree t-PA and a complex having a molecular weight of ̴ 180 kDa. HPLC fractionation to produce these three peaks at various timed intervals after injection of 125I-rt-PA showed each to have a similar initial rate half life in the rat circulation of 4-5 min. The function of these complexes as yet is unclear but since a high proportion of rt-PA is associated with a high molecular weight complex with a short half life in the rat, we suggest that the formation of this complex may be a mechanism by which t-PA activity is initially regulated and finally cleared from the rat circulation.

Permeability Enhancing and Chemotactic Activities of Lower Molecular Weight Degradation Products of Human Fibrinogen

1981 ◽  
Vol 45 (01) ◽  
pp. 090-094 ◽  
Author(s):  
Katsuo Sueishi ◽  
Shigeru Nanno ◽  
Kenzo Tanaka
Keyword(s):  
Molecular Weight ◽  
Degradation Products ◽  
Electron Microscopic Observation ◽  
Chemotactic Activity ◽  
Lower Molecular Weight ◽  
Electron Microscopic ◽  
Human Fibrinogen ◽  
Rabbit Skin ◽  
Molecular Weights ◽  
Active Fragments

SummaryFibrinogen degradation products were investigated for leukocyte chemotactic activity and for enhancement of vascular permeability. Both activities increased progressively with plasmin digestion of fibrinogen. Active fragments were partially purified from 24 hr-plasmin digests. Molecular weights of the permeability increasing and chemotactic activity fractions were 25,000-15,000 and 25,000 respectively. Both fractions had much higher activities than the fragment X, Y, D or E. Electron microscopic observation of the small blood vessels in rabbit skin correlated increased permeability with the formation of characteristic gaps between adjoining endothelial cells and their contraction.These findings suggest that lower molecular weight degradation products of fibrinogen may be influential in contributing to granulocytic infiltration and enhanced permeability in lesions characterized by deposits of fibrin and/or fibrinogen.

Toxicity of Heparinoids, with Special Reference to the Precipitation of Fibrinogen

1964 ◽  
Vol 12 (01) ◽  
pp. 232-261 ◽  
Author(s):  
S Sasaki ◽  
T Takemoto ◽  
S Oka
Keyword(s):  
Molecular Weight ◽  
Dextran Sulfate ◽  
Anticoagulant Activity ◽  
Molecular Structures ◽  
Severe Reaction ◽  
Clinical Use ◽  
Molecular Weights ◽  
Close Relationship

SummaryTo demonstrate whether the intravascular precipitation of fibrinogen is responsible for the toxicity of heparinoid, the relation between the toxicity of heparinoid in vivo and the precipitation of fibrinogen in vitro was investigated, using dextran sulfate of various molecular weights and various heparinoids.1. There are close relationships between the molecular weight of dextran sulfate, its toxicity, and the quantity of fibrinogen precipitated.2. The close relationship between the toxicity and the precipitation of fibrinogen found for dextran sulfate holds good for other heparinoids regardless of their molecular structures.3. Histological findings suggest strongly that the pathological changes produced with dextran sulfate are caused primarily by the intravascular precipitates with occlusion of the capillaries.From these facts, it is concluded that the precipitates of fibrinogen with heparinoid may be the cause or at least the major cause of the toxicity of heparinoid.4. The most suitable molecular weight of dextran sulfate for clinical use was found to be 5,300 ~ 6,700, from the maximum value of the product (LD50 · Anticoagulant activity). This product (LD50 · Anticoagulant activity) can be employed generally to assess the comparative merits of various heparinoids.5. Clinical use of the dextran sulfate prepared on this basis gave satisfactory results. No severe reaction was observed. However, two delayed reactions, alopecia and thrombocytopenia, were observed. These two reactions seem to come from the cause other than intravascular precipitation.

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