The Interaction of Polymerizing Systems with Rubber and Its Homologs. II. Interaction of Rubber in the Polymerization of Methyl Methacrylate and of Styrene

1955 ◽  
Vol 28 (1) ◽  
pp. 72-83
Author(s):  
F. M. Mebrett
Keyword(s):  
Molecular Weight ◽  
General Feature ◽  
Synthetic Polymers ◽  
The Other ◽  
Short Side ◽  
Polymer Systems ◽  
Colloidal Properties ◽  
Rate Of Polymerization ◽  
Graft Polymers ◽  
Vinyl Polymer

Abstract In Part I of this investigation, the effect of dihydromyrcene on four vinyl polymerizing systems was studied, and it was found that this compound reduces both the molecular weight of the polymer formed and the rate of polymerization. With rubber, the results are more complicated. A method for separating the simple polymers from the graft (compound) polymers is developed. This method is based on the peculiar colloidal properties of the graft polymers. These separations show that interaction between the natural and synthetic polymers depends on the catalyst used for initiating the polymerization and, therefore, that more than simple transfer is involved. Thus, with benzoyl peroxide, numerous very short side chains are combined with the rubber, while the free vinyl polymer chain grows to approximately the length predicted from known data. With azoisobutyronitrile, on the other hand, there is little or no reaction between the rubber and vinyl component. It is suggested that the formation of these very short grafted chains in place of the expected long ones may be a general feature of rubber-polymer systems of this type.

The Kidney and Fibrinolysis

1970 ◽  
Vol 24 (01/02) ◽  
pp. 026-032 ◽  
Author(s):  
N. A Marsh
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Enzyme System ◽  
Normal Animal ◽  
Fibrinolytic Enzyme ◽  
The Other ◽  
Exclusion Chromatography ◽  
Normal Urine ◽  
Renal Origin ◽  
Molecular Exclusion Chromatography

SummaryMolecular exclusion chromatography was performed on samples of urine from normal and aminonucleoside nephrotic rats. Normal urine contained 2 peaks of urokinase activity, one having a molecular weight of 22,000 and the other around 200,000. Nephrotic urine contained three peaks of activity with MW’s 126,000, 60,000 and 30,000. Plasma activator determined from euglobulin precipitate had a MW. in excess of 200,000. The results indicate that in the normal animal, plasma plasminogen activator does not escape into the urine in substantial quantities but under the conditions of extreme proteinuria there may be some loss through the kidney. The alteration in urokinase output in nephrotic animals indicates a greatly disordered renal fibrinolytic enzyme system.The findings of this study largely support the hypothesis that plasma plasminogen activator of renal origin and urinary plasminogen activator (urokinase) are different molecular species.

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.

scholarly journals Radiation-Induced Asymmetric Grafting of Different Monomers into Base Films to Prepare Novel Bipolar Membranes

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2028
Author(s):  
Shin-ichi Sawada ◽  
Yasunari Maekawa
Keyword(s):  
Acrylic Acid ◽  
Anion Exchange ◽  
Graft Polymerization ◽  
The Other ◽  
Practical Applications ◽  
Bipolar Membranes ◽  
Graft Polymers ◽  
Grafting Reactions ◽  
Radiation Induced

We prepared novel bipolar membranes (BPMs) consisting of cation and anion exchange layers (CEL and AEL) using radiation-induced asymmetric graft polymerization (RIAGP). In this technique, graft polymers containing cation and anion exchange groups were introduced into a base film from each side. To create a clear CEL/AEL boundary, grafting reactions were performed from each surface side using two graft monomer solutions, which are immiscible in each other. Sodium p-styrenesulfonate (SSS) and acrylic acid (AA) in water were co-grafted from one side of the base ethylene-co-tetrafluoroethylene film, and chloromethyl styrene (CMS) in xylene was simultaneously grafted from the other side, and then the CMS units were quaternized to afford a BPM. The distinct SSS + AA- and CMS-grafted layers were formed owing to the immiscibility of hydrophilic SSS + AA and hydrophobic CMS monomer solutions. This is the first BPM with a clear CEL/AEL boundary prepared by RIAGP. However, in this BPM, the CEL was considerably thinner than the AEL, which may be a problem in practical applications. Then, by using different starting times of the first SSS+AA and second CMS grafting reactions, the CEL and AEL thicknesses was found to be controlled in RIAGP.

Barricyclin D1—a dimeric ellagitannin with a macrocyclic structure—and accompanying tannins from Barringtonia racemosa

2021 ◽  
Author(s):  
Shinji Yoshikawa ◽  
Lih-Geeng Chen ◽  
Morio Yoshimura ◽  
Yoshiaki Amakura ◽  
Tsutomu Hatano ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Natural Resource ◽  
The Other ◽  
Hydrolysable Tannin ◽  
The Family ◽  
Macrocyclic Structure

Abstract Our examination of high molecular weight polyphenolic constituents in the leaves of Barringtonia racemosa of the family Lecythidaceae uncovered five previously undescribed ellagitannins. One, barringtin M1 (1), among them was a hydrolysable tannin monomer, while remaining four, barringtins D1 (2), D2 (3), D3 (4) and barricyclin D1 (5), were all dimers. Barricyclin D1 had a first macrocyclic structure formed from casuarictin (6) and tellimagrandin I (7), and the other ellagitannins had structures related to 5. Two additional known phenolics, valoneic acid dilactone (8) and schimawalin A (9), were also isolated from the leaves. These results suggested that the leaves of B. racemosa is a natural resource rich in hydrolysable tannin oligomers.

CO-ORDINATION COMPLEXES OF TITANIUM (IV) HALIDES: II. PREPARATION AND INFRARED SPECTRA OF THE COMPLEXES OF TITANIUM TETRACHLORIDE WITH DIESTERS OF α,ω-DICARBOXYLIC ACIDS AND COMPARISON WITH ANALOGOUS COMPLEXES OF ZIRCONIUM TETRACHLORIDE AND TIN TETRACHLORIDE

1961 ◽  
Vol 39 (11) ◽  
pp. 2343-2352 ◽  
Author(s):  
Ernest Rivet ◽  
Real Aubin ◽  
Roland Rivest
Keyword(s):  
Molecular Weight ◽  
Infrared Spectra ◽  
Titanium Tetrachloride ◽  
Complex Molecule ◽  
Dicarboxylic Acids ◽  
The Other ◽  
Zirconium Tetrachloride ◽  
Melting Points ◽  
Zirconium Complexes ◽  
Tin Tetrachloride

Co-ordination complexes between diesters of α,ω-dicarboxylic acids and titanium tetrachloride, tin tetrachloride, and zirconium tetrachloride have been prepared. The analytical results, the infrared spectra, the melting points, and the molecular-weight determinations indicate that for the titanium and zirconium complexes, two types of complexes are obtained, one having a general formula MX4•1 diester in which chelate rings from five to nine atoms are formed and the other one, 2MX4•1 diester in which there are two 4-membered rings per complex molecule. With tin tetrachloride only one type of complex is formed, which has two tin tetrachlorides and two diesters per complex molecule.

Effect on Polymer Chain Structure Caused by the Molar Fraction of 4-Hydroxybutyrate in Poly(3-hydroxybutyrate- co -4-hydroxybutyrate)

2012 ◽  
Vol 602-604 ◽  
pp. 776-780
Author(s):  
Zhi Qiang Li ◽  
Mei Li ◽  
Wei Jia Fan
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Polymer Chain ◽  
Molar Fraction ◽  
Chain Structure ◽  
The Other ◽  
Mean Square ◽  
Polarizing Microscope ◽  
Other Hand ◽  
The Mean

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)copolymer [P(3HB-co-4HB)] is a kind of biodegradable high molecular polymer produced by bioaccumulation. Because of the good biodegradability and biocompatibility, P(3HB-co-4HB)s have attracted wide attention . At first, the intrinsic viscosity[η] in good solvent of P(3HB-co-4HB) s with varying contents of 4HB was investigated in different temperature. Second, observed the changes of crystallization gathered state caused by the varying contents of 4HB by polarizing microscope. The results show that to the P(3HB-co-4HB)s in same molecular weight, the intrinsic viscosity[η] in good solvent barely changes when the mole fractions of 4HB increase. On the other hand, the mean square end to end distances[0] of macromolecular flexible chains increase with the mole fractions of 4HB. At the same time, the states of aggregation change from spherulites to dendrites. In this investigation, we discuss the reasons of the differences in depth.

scholarly journals Bridge-therapy with enoxaparin in the preoperative period of endarterectomy

2010 ◽  
Vol 68 (5) ◽  
pp. 775-777
Author(s):  
Jair Leopoldo Raso ◽  
Rogério Zenóbio Darwich ◽  
Francisco de Lucca Jr ◽  
Romeu Valle Santana ◽  
Marco Túlio Tanure ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Mortality Rate ◽  
Prospective Study ◽  
Low Molecular Weight Heparin ◽  
The Other ◽  
Low Molecular Weight ◽  
Preoperative Period ◽  
Safe Strategy ◽  
A Prospective Study ◽  
Bridge Therapy

Cervical clot is one of the complications of endarterectomy. This risk may be higher in patients using aspirin or clopidogrel. On the other hand, stroke may occur if the medication is interrupted before surgery. We carried out a prospective study of 124 endarterectomies in 119 patients in which aspirin or clopidogrel was stopped and a bridge-therapy with enoxaparin was administered preoperatively. There was no case of stroke during the period of the bridge-therapy. One patient developed cervical clot (0.8%) in the fifth postoperative day. Mortality rate in this series was 0.8%. There was no complication directly related to the use of enoxaparin. Bridge-therapy with low molecular weight heparin is a safe strategy for patients elected for endarterectomy

scholarly journals DNA and proteins of the nuclear matrix are the main targets of benzo[a]pyrene's action in rat hepatocytes.

1993 ◽  
Vol 40 (4) ◽  
pp. 559-562 ◽  
Author(s):  
P Widłak ◽  
J Rzeszowska-Wolny
Keyword(s):  
Molecular Weight ◽  
Dna Adducts ◽  
Dna Sequences ◽  
Nuclear Matrix ◽  
Rat Hepatocytes ◽  
The Other ◽  
Matrix Proteins ◽  
Nuclear Matrix Proteins ◽  
Cultured Rat Hepatocytes ◽  
High Molecular Weight Proteins

The binding of [14C]benzo[a]pyrene (B[a]P) to DNA and proteins in total nuclei and subnuclear fractions of cultured rat hepatocytes was compared. The main targets of B[a]P were non-histone high molecular weight proteins of the nuclear matrix and DNA sequences attached to this structure. Following 24 h exposure to B[a]P the amounts of adducts in the nuclear matrix DNA and proteins were twice as high as in total nuclei. After withdrawal of the carcinogen containing medium the level of B[a]P-induced adducts gradually decreased but always remained the highest in the nuclear matrix proteins. Removal of adducts from the nuclear matrix DNA was more efficient than from the other DNA fractions, and 72 h after exposure to the carcinogen the level of DNA adducts in this fraction was similar to that in total nuclei.

The structure and distribution of proteochondroitin sulphate during the formation of chick embryo feather germs

Development ◽  
1987 ◽  
Vol 100 (3) ◽  
pp. 501-512 ◽  
Author(s):  
KUNIO KITAMURA
Keyword(s):  
Molecular Weight ◽  
Chick Embryo ◽  
Basement Membrane ◽  
The Other ◽  
Dorsal Skin ◽  
Superficial Dermis ◽  
Dermal Cells ◽  
Asymmetrically Distributed ◽  
Slow Turnover ◽  
Feather Buds

The dorsal skin of the chick embryo, in which feather germ forms, was found to synthesize two proteochondroitin sulphates, PCS-I and PCS-II and a proteoheparan sulphate, PHS. A monoclonal antibody (I3B9) was prepared against PCS-I, a higher molecular weight proteochondroitin sulphate. Distribution of PCS-I was immunohistochemically studied using I3B9. PCS-I was found in the epidermis, basement membrane and superficial dermis prior to formation of feather rudiments. As the feather rudiments formed, PCS-I was noted in a condensed area of dermal cells and in the basement membrane, while PCS-I decreased remarkably in the epidermal placode. The formation of feather buds resulted in a decrease in PCS-I in the region of dermal condensation and the basement membrane situated above this region. PCS-I was asymmetrically distributed in the feather filaments. The turnover of proteochondroitin sulphate was studied using autoradiography of [35S]sulphate. Proteochondroitin sulphate in the basement membrane and condensed dermis of the feather rudiments showed very slow turnover. On the other hand, the outgrowth of feather buds caused rapid turnover of proteochondroitin sulphate in the region of dermal condensation and basement membrane situated above this region. The mechanism for the uneven distribution of PCS-I during feather germ formation is discussed.

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