Polysaccharides from the Flowers of Malva silvestris L., ssp. mauritiana (L.) THELL.: The Structure of D-Glucan

1992 ◽  
Vol 57 (11) ◽  
pp. 2400-2406 ◽  
Author(s):  
Peter Capek
Keyword(s):  
Molecular Weight ◽  
Ion Exchange ◽  
Average Molecular Weight ◽  
Linear Structure ◽  
Gel Chromatography ◽  
Spectroscopic Investigations ◽  
Glycosidic Bonds

The neutral polysaccharide α-D-glucan was isolated from the flowers of Malva silvestris L., ssp. mauritiana (L.) THELL. using a combination of ion exchange and gel chromatography. It was homogeneous under the conditions of free electrophoresis of average molecular weight Mn 25260. The chemical and spectroscopic investigations indicated a linear structure of the polysaccharide in which the α-D-glucopyranose units were linked predominantly by 1→6 glycosidic bonds, while some saccharides were the place of branching in position C-3.

scholarly journals The molecular-weight distribution of glycosaminoglycans

1973 ◽  
Vol 135 (4) ◽  
pp. 631-637 ◽  
Author(s):  
John J. Hopwood ◽  
H. Clem Robinson
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Chondroitin Sulphate ◽  
Average Molecular Weight ◽  
Length Distribution ◽  
Accurate Estimation ◽  
Distribution Data ◽  
Gel Chromatography ◽  
Chain Length Distribution

1. A rapid and sensitive method for the accurate estimation of the molecular-weight distribution of keratan sulphate and chondroitin sulphate isolated from adult bovine nasal septum and intervertebral disc is described. The method utilizes gel chromatography of reductively labelled glycosaminoglycan and end-group estimation of number-average molecular weight for each fraction across the peak of eluted glycosaminoglycan. 2. Chain-length distribution data obtained by this procedure are used to evaluate mechanisms of chondroitin sulphate biosynthesis.

Physicochemical study of complexation and ion-exchange properties of 2-hydroxy-4-ethoxypropiophenone—ethylene glycol polymer

1994 ◽  
Vol 6 (2) ◽  
pp. 123-132 ◽  
Author(s):  
Jayesh R Patel ◽  
Dipan H Sutaria ◽  
Magan N Patel
Keyword(s):  
Molecular Weight ◽  
Ion Exchange ◽  
Ethylene Glycol ◽  
Polyphosphoric Acid ◽  
Average Molecular Weight ◽  
Thermal Studies ◽  
Conductometric Titration ◽  
Number Average Molecular Weight ◽  
Elemental Analyses ◽  
Exchange Properties

Copolymers (HEPP-EG) were synthesized by the condensation of 2-hydroxy-4-ethoxypropiophenone with ethylene glycol in presence of polyphosphoric acid as a catalyst. The copolymers were characterized by elemental analyses, IR spectra, viscosity and thermal studies. The number-average molecular weight (Mn) was measured by non-aqueous conductometric titration. The copolymer HEPP-EG-6 was complexed with metal ions, Cu2+, Ni2+, Co2, Mn2+ and Zn2+ and characterized. Chelation ion-exchange properties have been studied by employing the batch equilibration method.

scholarly journals Synthesis and thermal decomposition kinetics of moisture curable polyurethane films as a reinforcing material for cultural relics

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Xing Zhao ◽  
Liqin Wang ◽  
Lang Guo ◽  
Yanni Ma ◽  
Ziming Wang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Thermal Decomposition ◽  
Average Molecular Weight ◽  
Decomposition Kinetics ◽  
Thermal Decomposition Kinetics ◽  
Gel Chromatography ◽  
Flexible Films ◽  
Before And After ◽  
Two Stages ◽  
Cultural Relics

AbstractIn situ consolidation is the most common treatment to conserve cultural relics, but materials for preserving fragile organic cultural relics in humid archaeological excavation sites are scarce. To solve the problem, a moisture-curable polyurethane (MCPU) prepolymer was synthesized by reacting isophorone diisocyanate with polyethylene glycol 600. The standard acetone–dibutylamine method, Fourier transform infrared spectroscopy, gel chromatography and thermogravimetric analysis were utilized to determine the change in isocyanate groups before and after the reaction, the prepolymer molecular weight, the thermal decomposition kinetic parameters and the MCPU film lifetime. The results showed that the number-average molecular weight of the prepolymer was 749, and the weight average molecular weight was 1684. Isophorone groups in the prepolymer react with moisture in the air to form colorless, transparent, flexible films. The thermal decomposition of the MCPU films was a first-order reaction, and the decomposition process consisted of two stages. The Dakin equation was used to obtain the thermal aging equation lg t = 4600.82/T − 8.07, meaning that at 15 °C, the sample has an approximately 150-year lifetime. A new conservation material was developed, and its thermal decomposition kinetics were studied, which are significant for the conservation of fragile organic cultural relics in humid environments.

Separation and Gel Permeation Analysis of natural Emulsion Stabilizers

1968 ◽  
Vol 8 (03) ◽  
pp. 253-259 ◽  
Author(s):  
C.A. Stout ◽  
S.W. Nicksic
Keyword(s):  
Molecular Weight ◽  
Ion Exchange ◽  
Crude Oil ◽  
Southern California ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Crude Oils ◽  
Ionic Character ◽  
Number Average Molecular Weight ◽  
Gel Permeation

Abstract The materials that stabilize emulsions of some Southern California crude oils were isolated from the produced crude. These substances were separated into acidic and nonionic fractions by ion exchange chromatography. Each fraction was further broken into groups of homogeneous molecular weight composition by gel permeation chromatography. Both ionic character and molecular weight of the individual fractions are reflected in the properties of the original crude oil emulsion. Specifically, the more acidic and the higher molecular weight fractions appear to be the most effective stabilizers. Introduction The treatment of oilfield emulsions is a continuing problem for the oil industry. In almost all cases, these are water-in-oil emulsions. Much more is known about the formation and stabilization of oil-in-water (O/W) emulsions than of the water-in-oil (W/O) type. To understand W/O emulsions, more information is needed on the materials responsible for their formation and stabilization. This is especially true in the case of oilfield emulsions where the stabilizing materials are complex mixtures of large asphaltene-like molecules. To study the chemical and physical properties of these emulsion stabilizers, it is necessary first to separate them from crude oil. This separation was achieved in the case of two Southern California crude oils. The materials that were isolated appear at first to be little different from an asphaltene mixture. However, if a mixture of distilled water and mineral oil containing about 1 percent of the natural emulsion stabilizers is passed through a colloid mill, the W/O emulsion formed may be stored in the laboratory for many months without any sign of breaking. This could not be done using undifferentiated asphaltenes from the same wells, indicating that there is a real difference between these materials and ordinary asphaltenes. The colloid mill used to generate the emulsion was required because the natural emulsion stabilizers had very little effect on oil-water interfacial tension. The one characteristic - complexity of composition - that emulsion stabilizers share with asphaltenes makes virtually impossible the exact structure determination of the components of the mixture. For this reason, it was decided to investigate first the influence of molecular weight on the ability of these materials to stabilize emulsions. The emulsion stabilizers were first separated into acidic and neutral fractions according to whether or not the material was retained on a weakly basic ion exchange column. The extraction procedure was not designed to remove basic components from the oils, and no attempt to isolate such a fraction was made. Following this separation selected fractions were analyzed by gel permeation chromatography. Gel permeation separates according to molecular size, largely independently of chemical or polar characteristics. A heterogeneous mixture is separated into a number of fractions having much more homogeneous molecular weight distribution. A number average molecular weight of each fraction is therefore close to the true molecular weight of the principal component of that fraction. The fraction weights, expressed as weight percent of the sample, and the number average molecular weight of a representative selection of the fractions, will be referred to in this paper as the molecular weight profile of the original sample. DESCRIPTION OF GEL PERMEATION ANALYSIS The first reported gel permeation analyses were for separating partially hydrolyzed protein molecules in an aqueous system using expanded starch granules. Most of the theoretical work on gel permeation has been done by biochemists. SPEJ P. 253ˆ

The Structure of Radiation Cross-Linked Poly (ethylene oxide) Gels

1971 ◽  
Vol 29 ◽  
pp. 76-77
Author(s):  
C. E. Cluthe ◽  
G. G. Cocks
Keyword(s):  
Molecular Weight ◽  
Ethylene Oxide ◽  
Parallel Plate ◽  
Average Molecular Weight ◽  
Radical Reaction ◽  
Free Radical Reaction ◽  
Nitrogen Gas ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Initial Viscosity

Aqueous solutions of a 1 weight-per cent poly (ethylene oxide) (PEO) were degassed under vacuum, transferred to a parallel plate viscometer under a nitrogen gas blanket, and exposed to Co60 gamma radiation. The Co60 source was rated at 4000 curies, and the dose ratewas 3.8x105 rads/hr. The poly (ethylene oxide) employed in the irradiations had an initial viscosity average molecular weight of 2.1 x 106.The solutions were gelled by a free radical reaction with dosages ranging from 5x104 rads to 4.8x106 rads.

Identification of Fibrinogen Derivatives in Plasma Samples

1972 ◽  
Vol 27 (03) ◽  
pp. 610-618 ◽  
Author(s):  
H Graeff ◽  
R von Hugo
Keyword(s):  
Molecular Weight ◽  
Gel Electrophoresis ◽  
Gel Chromatography ◽  
Agarose Gel ◽  
Plasma Samples ◽  
Methodological Study ◽  
Parent Molecule ◽  
Electrophoretic Mobilities ◽  
Fibrin Monomer

SummaryThe observation of fibrinogen derivatives with a molecular weight higher than the parent molecule in human cases of DIC initiated the present methodological study. These derivatives were identified by the following methods : 2.5 M β-alanine precipitation of the plasma samples, PAA gel electrophoresis, intra gel immunoprecipitation and agarose gel chromatography. In the plasma of a patient with severe eclampsia and laboratory signs of DIC two derivatives with a molecular weight higher than that of fibrinogen were identified according to their relative electrophoretic mobilities: 0.18 and 0.28 × 10−5 cm2/V × sec (fibrinogen: 0.43 × 10−5 cm2/V × sec). Electrophoretic studies in the presence of 5 M urea indicated that the 0.28 derivative is a complex probably formed by fibrinogen and a fibrin monomer.

The Relation Between VIIIR:AG and VIII:C Studied with Two Antisera

1979 ◽  
Author(s):  
H. P. Muller ◽  
N. H. van Tilburg ◽  
R. M. Bertina ◽  
J. J. Veltkamp
Keyword(s):  
Molecular Weight ◽  
High Salt ◽  
Low Molecular Weight ◽  
Gel Chromatography ◽  
Specific Antibodies ◽  
Specific Effects ◽  
Normal Plasma ◽  
Coagulant Activity ◽  
Sterical Hindrance ◽  
Inhibitory Antibodies

FVIII was separated into low molecular weight FVIII (LMW FVIII) and high molecular weight FVIII (HMW FVIII) by gel chromatography in the presence of high salt concentration or by high salt elution of LMW FVIII from FVIII bound to anti HMW FVII-Sepharose. Specific antibodies were raised in rabbits against HMW FVIII and LMW FVIII. After removal of the contaminating anti HMW activities the rabbit anti LMW FVIII was still able to neutralize the FVIII coagulant activity of normal plasma and of IMW FVIII with canparable efficiency and it had no effect on the VIIIR:WF of FVIII in normal plasma or in HMW FVIII. Anti LMW FVIII does not bind to HMW FVIII and does not precipitate FVIII as tested by counter immunoelectrophoresis. Rabbit anti HMW FVIII precipitates FVIII in normal plasma, inhibits VIIIR:WF activity, while it has no effect on the FVIII coagulant activity of LMW FVIII. The coagulant activity of FVIII in normal plasma is slightly inhibited by anti HMW FVIII presumably by non-specific effects (sterical hindrance). It is concluded that inhibitory antibodies against VIII:C raised in rabbits recognize antigenic structures only present on LMW FVIII. Antibodies against HMW FVIII raised in rabbits appears to recognize structures only present on HMW FVIII.

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