Control of Molecular Weight in α-Olefin−Carbon Monoxide Alternating Copolymerization. A Way to High Molecular Weight Propene−Carbon Monoxide Thermoplastic Elastomers

1996 ◽  
Vol 29 (13) ◽  
pp. 4806-4807 ◽  
Author(s):  
Adnan S. Abu-Surrah ◽  
Roland Wursche ◽  
Bernhard Rieger ◽  
Gabriele Eckert ◽  
Wolfgang Pechhold
Keyword(s):  
Molecular Weight ◽  
Carbon Monoxide ◽  
High Molecular Weight ◽  
Thermoplastic Elastomers ◽  
Alternating Copolymerization

Studies on Influencing Factors of Polyketone Molecular Weight by Palladium Catalyzed Alternating Copolymerization with Carbon Monoxide and Ethylene

2013 ◽  
Vol 634-638 ◽  
pp. 2014-2018
Author(s):  
Jia Yao Du ◽  
Liang Chen ◽  
Wen Wei ◽  
Lin Deng ◽  
Ling Gao ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Carbon Monoxide ◽  
Water Content ◽  
Temperature Rise ◽  
Palladium Catalyzed ◽  
System Temperature ◽  
Main Factors ◽  
Increasing Temperature ◽  
Alternating Copolymerization ◽  
Strong Acids

With Pd(AcO)2DPPP as catalytic precursor of CO/C2H4 alternating copolymerization. The main factors which affect the molecular weight of polyketone were studied. The results showed that: Temperature was the most important factor in copolymerization. The polyketone molecular weight lower faster with increasing temperature, have a decrease of 53% when system temperature rise from 70°C to 80°C, and the palladium-catalyzed progenitor easy to decomposition and become deactivation. Adding pressure was in favor of the increase of copolymerization rate and molecular weight. Water content in methanol solvent was sensitive to copolymerization rate, as far as molecular weight was concerned, it made no difference. HClO4 and other strong acids in the catalytic system will help improve the molecular weight of the polyketone.

Microtubule motors and other maps

1990 ◽  
Vol 48 (3) ◽  
pp. 1-1
Author(s):  
Richard B. Vallee
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cytoplasmic Dynein ◽  
Organelle Transport ◽  
Structural Components ◽  
Microtubule Associated Proteins ◽  
Microtubule Motors ◽  
Associated Proteins ◽  
The Subject ◽  
Intracellular Motility

Microtubules are involved in a number of forms of intracellular motility, including mitosis and bidirectional organelle transport. Purified microtubules from brain and other sources contain tubulin and a diversity of microtubule associated proteins (MAPs). Some of the high molecular weight MAPs - MAP 1A, 1B, 2A, and 2B - are long, fibrous molecules that serve as structural components of the cytamatrix. Three MAPs have recently been identified that show microtubule activated ATPase activity and produce force in association with microtubules. These proteins - kinesin, cytoplasmic dynein, and dynamin - are referred to as cytoplasmic motors. The latter two will be the subject of this talk.Cytoplasmic dynein was first identified as one of the high molecular weight brain MAPs, MAP 1C. It was determined to be structurally equivalent to ciliary and flagellar dynein, and to produce force toward the minus ends of microtubules, opposite to kinesin.

Studies on the Functionality of Newly Synthesized Fibrinogen after Treatment of Acute Myocardial Infarction with Streptokinase, Increase in the Rate of Fibrinopeptide Release

1993 ◽  
Vol 70 (06) ◽  
pp. 0978-0983 ◽  
Author(s):  
Edelmiro Regano ◽  
Virtudes Vila ◽  
Justo Aznar ◽  
Victoria Lacueva ◽  
Vicenta Martinez ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Molecular Weight ◽  
Steady State ◽  
High Molecular Weight ◽  
Coronary Arteries ◽  
Risk Index ◽  
Weight Fraction ◽  
High Molecular Weight Fraction ◽  
Fibrinopeptide A

SummaryIn 15 patients with acute myocardial infarction who received 1,500,000 U of streptokinase, the gradual appearance of newly synthesized fibrinogen and the fibrinopeptide release during the first 35 h after SK treatment were evaluated. At 5 h the fibrinogen circulating in plasma was observed as the high molecular weight fraction (HMW-Fg). The concentration of HMW-Fg increased continuously, and at 20 h reached values higher than those obtained from normal plasma. HMW-Fg represented about 95% of the total fibrinogen during the first 35 h. The degree of phosphorylation of patient fibrinogen increased from 30% before treatment to 65% during the first 5 h, and then slowly declined to 50% at 35 h.The early rates of fibrinopeptide A (FPA) and phosphorylated fibrinopeptide A (FPAp) release are higher in patient fibrinogen than in isolated normal HMW-Fg and normal fibrinogen after thrombin addition. The early rate of fibrinopeptide B (FPB) release is the same for the three fibrinogen groups. However, the late rate of FPB release is higher in patient fibrinogen than in normal HMW-Fg and normal fibrinogen. Therefore, the newly synthesized fibrinogen clots faster than fibrinogen in the normal steady state.In two of the 15 patients who had occluded coronary arteries after SK treatment the HMW-Fg and FPAp levels increased as compared with the 13 patients who had patent coronary arteries.These results provide some support for the idea that an increased synthesis of fibrinogen in circulation may result in a procoagulant tendency. If this is so, the HMW-Fg and FPAp content may serve as a risk index for thrombosis.

Sign in / Sign up

Export Citation Format

Share Document