Adsorption of high-molecular-weight hydrocarbons from residual petroleum products on type a zeolite

1974 ◽  
Vol 10 (6) ◽  
pp. 426-429
Author(s):  
M. I. Fal'kovich ◽  
Yu. A. �l'tekov ◽  
V. T. Solodovnikova ◽  
V. M. Ivanov
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Type A ◽  
Petroleum Products ◽  
Residual Petroleum

scholarly journals Tandem Synthesis of Ultra-High Molecular Weight Drag Reducing Poly-α-Olefins for Low-Temperature Pipeline Transportation

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3930
Author(s):  
Ilya E. Nifant’ev ◽  
Alexander N. Tavtorkin ◽  
Alexey A. Vinogradov ◽  
Sofia A. Korchagina ◽  
Maria S. Chinova ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Temperature ◽  
High Molecular Weight ◽  
Petroleum Products ◽  
Additional Treatment ◽  
Reaction Products ◽  
Pipeline Transportation ◽  
Stage Synthesis ◽  
Reaction Media ◽  
Ultra High Molecular Weight

Ultra-high molecular weight poly-α-olefins are widely used as drag reducing agents (DRAs) for pipeline transportation of oil and refined petroleum products. The synthesis of polyolefin DRAs is based on low-temperature Ziegler–Natta (ZN) polymerization of higher α-olefins. 1-Hexene based DRAs, the most effective at room temperature, typically lose DR activity at low temperatures. The use of 1-hexene copolymers with C8–C12 linear α-olefins appears to offer a solution to the problem of low-temperature drag reducing. The present work aims to develop two-stage synthesis of polyolefin DRAs that is based on selective oligomerization of ethylene in the presence of efficient chromium/aminodiphosphine catalysts (Cr-PNP), followed by polymerization of the olefin mixtures, formed at oligomerization stage, using efficient titanium–magnesium ZN catalyst. We have shown that oligomerization of ethylene in α-olefin reaction media proceeds faster than in saturated hydrocarbons, providing the formation of 1-hexene, 1-octene, and branched C10 and C12 olefins; the composition and the ratio of the reaction products depended on the nature of PNP ligand. Oligomerizates were used in ZN polymerization ‘as is’, without additional treatment. Due to branched character of C10+ hydrocarbons, formed during oligomerization of ethylene, resulting polyolefins demonstrate higher low-temperature DR efficiency at low polymer concentrations (~1 ppm) in comparison with benchmark polymers prepared from the mixtures of linear α-olefins and from pure 1-hexene. We assume that faster solubility and more efficient solvation of the polyolefins, prepared using ‘tandem’ ethylene-based process, represent an advantage of these type polymers over conventional poly(1-hexene) and linear α-olefin-based polymers when used as ‘winter’ DRAs.

Hydrazines as Rubber Softeners

1936 ◽  
Vol 9 (2) ◽  
pp. 339-349
Author(s):  
I. Williams ◽  
C. C. Smith
Keyword(s):  
Molecular Weight ◽  
Power Consumption ◽  
Organic Acid ◽  
High Molecular Weight ◽  
Lead Dioxide ◽  
Soft Materials ◽  
Mechanical Efficiency ◽  
Petroleum Products ◽  
Acid Anhydride ◽  
Uniform Manner

Abstract THE process of softening rubber has received much less study than its importance deserves. Since the method of softening rubber by mastication was devised by Hancock, the greatest advances have been in the introduction of machines of greater mechanical efficiency and greater capacity. Prior to 1920 the effect of such variables as temperature was little understood. Long and inefficient periods of milling at high temperatures were common. In case milling did not produce the required plasticity, recourse was had to the addition of oils, resins, and other soft materials sometimes in considerable amounts. Such conditions have not yet entirely disappeared. Various methods have recently been proposed for plasticizing rubber in a more uniform manner and with less power consumption. Worthington and Hyde (24) softened rubber by heating it in a nonoxidizing atmosphere. Bradley and Ferrettie (1) concluded that the rubber should be water-soaked before it is heated and should be kept wet during the process. Tuley (21) patented the process of softening rubber by the addition of lead dioxide during the period of mastication, and Gerke (7) used a mixture of lead dioxide with an organic acid anhydride. Cruikshank (4) proposed the use of solvents containing alcohols of high molecular weight or sulfonated petroleum products as mastication assistants. According to Martin (10) the addition of nitrites to the latex before coagulation produces rubber of superior plasticity. Rubber softened by heating in an oxidizing atmosphere according to the method of Unger and Schidrowitz (22) has recently become a commercial product.

Isolation of intracisternal type A-particles and associated high-molecular-weight RNA after cell disruption by nitrogen cavitation

1979 ◽  
Vol 97 (1) ◽  
pp. 85-94 ◽  
Author(s):  
J. Nissen-Meyer ◽  
A. Åbro ◽  
T.S. Eikhom
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Type A ◽  
Cell Disruption

scholarly journals Five-Gene Cluster in Clostridium thermoaceticumConsisting of Two Divergent Operons Encoding Rubredoxin Oxidoreductase- Rubredoxin and Rubrerythrin–Type A Flavoprotein– High-Molecular-Weight Rubredoxin

2001 ◽  
Vol 183 (5) ◽  
pp. 1560-1567 ◽  
Author(s):  
Amaresh Das ◽  
Eric D. Coulter ◽  
Donald M. Kurtz ◽  
Lars G. Ljungdahl
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Gene Cluster ◽  
Anaerobic Bacteria ◽  
Type A ◽  
Amino Acid Sequences ◽  
Desulfovibrio Vulgaris ◽  
Visible Absorption ◽  
Stress Protection ◽  
Molecular Masses

ABSTRACT A five-gene cluster encoding four nonheme iron proteins and a flavoprotein from the thermophilic anaerobic bacteriumClostridium thermoaceticum (Moorella thermoacetica) was cloned and sequenced. Based on analysis of deduced amino acid sequences, the genes were identified asrub (rubredoxin), rbo (rubredoxin oxidoreductase), rbr (rubrerythrin), fprA (type A flavoprotein), and a gene referred to as hrb(high-molecular-weight rubredoxin). Northern blot analysis demonstrated that the five-gene cluster is organized as two subclusters, consisting of two divergently transcribed operons,rbr-fprA-hrb and rbo-rub. The rbr, fprA, and rub genes were expressed inEscherichia coli, and their encoded recombinant proteins were purified. The molecular masses, UV-visible absorption spectra, and cofactor contents of the recombinant rubrerythrin, rubredoxin, and type A flavoprotein were similar to those of respective homologs from other microorganisms. Antibodies raised againstDesulfovibrio vulgaris Rbr reacted with both native and recombinant Rbr from C. thermoaceticum, indicating that this protein was expressed in the native organism. Since Rbr and Rbo have been recently implicated in oxidative stress protection in several anaerobic bacteria and archaea, we suggest a similar function of these proteins in oxygen tolerance of C. thermoaceticum.

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.

Antioxidant activity of the high-molecular-weight (HMW) phenolic fraction of pecans

Planta Medica ◽  
2016 ◽  
Vol 81 (S 01) ◽  
pp. S1-S381
Author(s):  
P Greenspan ◽  
MB Kellett ◽  
RB Pegg
Keyword(s):  
Molecular Weight ◽  
Antioxidant Activity ◽  
High Molecular Weight ◽  
Phenolic Fraction

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.

The Effect of Dextran of Various Molecular Weight on the Coagulation in Dogs

1961 ◽  
Vol 06 (01) ◽  
pp. 015-024 ◽  
Author(s):  
Sven Erik Bergentz ◽  
Oddvar Eiken ◽  
Inga Marie Nilsson
Keyword(s):  
Molecular Weight ◽  
Body Weight ◽  
High Molecular Weight ◽  
Bleeding Time ◽  
Factor Vii ◽  
Low Molecular Weight ◽  
Factor V ◽  
Coagulation Mechanism ◽  
Coagulation Defects

Summary1. Infusions of low molecular weight dextran (Mw = 42 000) to dogs in doses of 1—1.5 g per kg body weight did not produce any significant changes in the coagulation mechanism.2. Infusions of high molecular weight dextran (Mw = 1 000 000) to dogs in doses of 1—1.5 g per kg body weight produced severe defects in the coagulation mechanism, namely prolongation of bleeding time and coagulation time, thrombocytopenia, pathological prothrombin consumption, decrease of fibrinogen, prothrombin and factor VII, factor V and AHG.3. Heparin treatment of the dogs was found to prevent the decrease of fibrinogen, prothrombin and factor VII, and factor V otherwise occurring after injection of high molecular weight dextran. Thrombocytopenia was not prevented.4. In in vitro experiments an interaction between fibrinogen and dextran of high and low molecular weight was found to take place in systems comprising pure fibrinogen. No such interaction occurred in the presence of plasma.5. It is concluded that the coagulation defects induced by infusions of high molecular weight dextran are due to intravascular coagulation.

Rapid Isolation of High Molecular Weight Urokinase from Native Human Urine

1982 ◽  
Vol 47 (03) ◽  
pp. 197-202 ◽  
Author(s):  
Kurt Huber ◽  
Johannes Kirchheimer ◽  
Bernd R Binder
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Human Urine ◽  
Gel Filtration ◽  
Chain Structure ◽  
The Other ◽  
Single Chain ◽  
Apparent Homogeneity ◽  
Sequential Adsorption

SummaryUrokinase (UK) could be purified to apparent homogeneity starting from crude urine by sequential adsorption and elution of the enzyme to gelatine-Sepharose and agmatine-Sepharose followed by gel filtration on Sephadex G-150. The purified product exhibited characteristics of the high molecular weight urokinase (HMW-UK) but did contain two distinct entities, one of which exhibited a two chain structure as reported for the HMW-UK while the other one exhibited an apparent single chain structure. The purification described is rapid and simple and results in an enzyme with probably no major alterations. Yields are high enough to obtain purified enzymes for characterization of UK from individual donors.

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