An Inorganic Rubber

1932 ◽  
Vol 5 (4) ◽  
pp. 585-586
Author(s):  
Paul Renaud
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Low Temperature ◽  
Osmotic Pressure ◽  
The Other ◽  
Low Molecular Weight ◽  
Solid Mixture

Abstract The hypotheses generally accepted for the structure of gels explain these phenomena in detail. The trimer, polymerized by heating, gives rise to chains of different sizes, which are able to unite and form a network. The latter contains in its meshes the trimer which has not reacted, and also polymers of low molecular weight. According to whether the latter form a liquid or solid mixture, the gum is optically liquid or solid. At low temperature, the network itself assumes a rigidity which it communicates to the entire mass. The thermo-mechanical properties show that this is true of all the gums. The presence of the network has little influence on the fusion of the intercellular product, whereas its influence on vaporization is great; in fact, the volume is as little affected by fusion as it is greatly changed by vaporization. It must therefore be the case that rupture of the meshes by pressure is more rapid than their formation by polymerization. The influence of benzine and of water, one of which dissolves the intercellular products and the other does not, shows the influence of osmotic pressure, to which Duclaux (see Bull. soc. chim., 33, 36 (1923)) has called attention.

scholarly journals TRANSLATABLE mRNA IN THE PERICARP OF TOMATO CULTIVARS DIFFERING IN CHILLING TOLERANCE

HortScience ◽  
1994 ◽  
Vol 29 (4) ◽  
pp. 252c-252
Author(s):  
Han-Ling Yu ◽  
Claude Willemot ◽  
Serge Yelle ◽  
Yves Castonguay ◽  
Paul Nadeau
Keyword(s):  
New York ◽  
Molecular Weight ◽  
Low Temperature ◽  
Lycopersicon Esculentum ◽  
Chilling Tolerance ◽  
The Other ◽  
Low Molecular Weight ◽  
Tomato Cultivars ◽  
Translatable Mrna ◽  
Basic Peptides

Translatable mRNAs from two tomato (Lycopersicon esculentum Mill.) cultivars differing in chilling tolerance were compared after 16 days of chilling at 4C and after return to 20C for 1 and 5 days. Before chilling, the translation products, resolved by 2D NEPHGE, showed significant differences between more tolerant `New York 280' (NY) and less tolerant `Early Cherry' (EC). In NY, chilling reduced the level of five to 10 mRNAs and enhanced or induced that of several other mRNAs. After transfer to 20C, the trend was progressively reversed. Changes in the levels of two low-molecular-weight basic peptides were most noticeable. One, absent in NY before chilling, was strongly expressed after chilling and 24 h after transfer to 20C, but disappeared 5 days after transfer. The level of this peptide increased slightly in EC at low temperature and was maintained after transfer to 20C. The level of the other, high in NY before chilling, was sharply reduced after chilling. In contrast, the level of this polypeptide was low in EC under all treatments.

Tuneable mechanical properties in low molecular weight gels

Soft Matter ◽  
2011 ◽  
Vol 7 (20) ◽  
pp. 9721 ◽  
Author(s):  
Lin Chen ◽  
Jaclyn Raeburn ◽  
Sam Sutton ◽  
David G. Spiller ◽  
James Williams ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Low Molecular Weight

Influence of low-molecular-weight copolymers of ethylene with vinyl acetate on the low-temperature properties of diesel fuel

1974 ◽  
Vol 10 (8) ◽  
pp. 615-618 ◽  
Author(s):  
G. G. Krasnyanskaya ◽  
B. V. Gryaznov ◽  
V. A. Kryunina ◽  
S. L. Lyubimova ◽  
V. N. Monastyrskii ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Temperature ◽  
Vinyl Acetate ◽  
Diesel Fuel ◽  
Low Molecular Weight

Research on Chemical Modification of Wood of Fast-Growing Poplar

2013 ◽  
Vol 749 ◽  
pp. 461-465
Author(s):  
De Jun Shen ◽  
Chang Hai Yu ◽  
Zhen Xing
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Structural Material ◽  
Chemical Modification ◽  
Orthogonal Test ◽  
Low Molecular Weight ◽  
Wood Structure ◽  
Optimum Conditions ◽  
Fast Growing ◽  
Performance Requirements

This topic is considered to modify the fast-growing Poplar to improve the properties, in order to fully meet the performance requirements for the structural material. This study aims to improve the dimensional stability and some other mechanical properties through impregnated with the low-molecular-weight PF resin. Through design orthogonal test in different mole ratio of Formaldehyde and Phenol, different amount of NaOH and PVA, we make PF resin to impregnate Poplar and pressing into laminated timber to measure bonding strength, MOR, MOE. The study indicated that: the optimum conditions of the low molecular weight PF resin for modify Poplar are: mole ratio of Formaldehyde and Phenol is 2.4, mole ratio of NaOH and phenol is 0.05, amount of PVA is 3% of the phenol. Under this condition Poplar specimen got the biggest increase in various properties and it can satisfy the requirements of the outdoor wood structure.

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

In Vitro Characterization Of Low Molecular Weight Fractions Of Heparin

1981 ◽  
Author(s):  
Jawed Fareed ◽  
Harry L Messmore ◽  
Daniel A Walz ◽  
Jean Choay ◽  
J C Lormeau
Keyword(s):  
Molecular Weight ◽  
The Other ◽  
Low Molecular Weight ◽  
In Vitro Test ◽  
Thrombin Time ◽  
Specific Test ◽  
Platelet Factor ◽  
At Iii ◽  
Heparin Fractions

Numerous extraction, chromatographic (ion exchange, gel, and affinity), chemical and enzymatic degradation methods have been employed to obtain heparin fractions. The present assays to evaluate potency (e.g. pharmacopeial and coagulant) do not truly reflect the antithrombotic properties of these fractions. In addition, the synthetic peptide substrate based assays to measure the anti Xa activity do not correlate with the coagulant anti Xa assays. We have developed an in vitro test battery to evaluate low molecular weight heparin fractions. Porcine mucosal heparin fractions are assayed for anti Xa activity in coagulant and amidolytic assays and the results are expressed as a ratio. The effect of these fractions on coagulant assays such as prothrombin time (PT), partial thromboplastin time (PTT), thrombin time (TT), Stypven time (ST) on freshly prepared normal human plasma (NHP) is determined The retention characteristics of these fractions on platelet factor 4 and AT-III bound sepharose columns were also determined. We have compared the extracted and chemically depolymerized heparin fractions and found that the anti Xa activity doesn’t always correlate with the other parameters studied. The extracted fractions were slightly stronger in the USP assays and showed a biphasic retention on the PF-4 column whereas the chemically depolymerized product showed only one peak. On the other hand, on the AT-III column both fractions showed similar elution patterns. Our studies suggest that heparin and its fractions exhibit differential behavior on various assays and a specific test may not be used as an index of the potency of their antithrombotic effects. Furthermore, the potency of these fractions should be stated on a weight basis when evaluated in the in vivo animal models rather than in terms of a specific test (e.g. anti Xa activity and US Pharmacopeial assays).

STUDIES ON THE ISOLATION AND NATURE OF THE 'TERREGENS FACTOR'

1954 ◽  
Vol 32 (1) ◽  
pp. 400-406 ◽  
Author(s):  
M. O. Burton ◽  
F. J. Sowden ◽  
A. G. Lochhead
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Ferric Iron ◽  
Test Organism ◽  
The Other ◽  
Inorganic Salts ◽  
Low Molecular Weight ◽  
Straight Chain ◽  
Heat Stable ◽  
Growth Promoting

A procedure is described for the production and concentration of the 'terregens factor' (TF), a bacterial growth promoting substance synthesized by Arthrobacter pascens and essential for the growth of Arthrobacter terregens. From culture filtrates of A. pascens cultivated in a medium of inorganic salts and sucrose, concentrates of TF may be obtained that are active at 0.001 μgm. Per ml., heat stable and contain about 12.7% nitrogen. Acid hydrolysis yielded a number of amino acids, including glutamic acid, glycine, α–alanine, valine, leucine, proline, lysine, and arginine, as well as some unidentified compounds; however, TF does not appear to be a low molecular weight straight chain peptide.Although TF contains no iron, it combines readily with ferrous or ferric iron to form reddish-brown complexes with this metal. Activity for A. terregens is shown by certain iron containing complexes as hemin, coprogen, and ferrichrome. On the other hand none is shown by cytochrome or pulcherrimin; however, aspergillic acid, structurally related to the latter, possesses some growth promoting activity for the test organism.

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