scholarly journals PHYSICOCHEMICAL STUDIES OF ALKALI LIGNINS. I. PREPARATION AND PROPERTIES OF FRACTIONS

1960 ◽  
Vol 38 (2) ◽  
pp. 248-258 ◽  
Author(s):  
P. R. Gupta ◽  
D. A. I. Goring
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Barium Chloride ◽  
Weight Fraction ◽  
Low Molecular Weight ◽  
Neutralization Equivalent ◽  
Visible Absorption ◽  
X Ray ◽  
Physicochemical Studies ◽  
Specific Volumes

Alkali lignin was prepared by cooking periodate lignin with sodium hydroxide. Fractionation by gradual decrease of pH was not possible as most of the lignin was precipitated sharply at pH 4.4. Fractionation could be achieved by addition of non-solvents such as acetone, dioxane, or ethanol to an alkaline aqueous solution of the lignin, but the initial fractions when separated could not be redissolved. This difficulty was overcome by using barium chloride as a precipitant when all the fractions remained soluble. X-Ray analysis revealed no difference between the insoluble and soluble fractions.The intrinsic viscosity of the fractions ranged from 0.027 to 0.585 g−1 dl. Reduced viscosities were considerably increased at lower ionic strength indicating that the molecule was a polyelectrolyte. The fractions possessed nearly constant methoxyl content (13%), visible absorption (0.28 cm−1 l g−1 at 5460 Å), U.V. absorption (18 cm−1 l. g−1 at 2800 Å), neutralization equivalent (1.3 meq g−1), and electrophoretic mobility (−12.6 × 10−5 cm2 v−1 sec−1). The partial specific volumes of a high and a low molecular weight fraction were 0.63 and 0.68 g−1 ml respectively.

In Vivo Studies on the Inhibition of Coagulation by Fractionated Heparin and by a Heparin Analogue I. Effects of Heparin Fractions

1981 ◽  
Vol 46 (03) ◽  
pp. 612-616 ◽  
Author(s):  
U Schmitz-Huebner ◽  
L Balleisen ◽  
F Asbeck ◽  
J van de Loo
Keyword(s):  
Molecular Weight ◽  
Day Treatment ◽  
Gel Filtration ◽  
Weight Fraction ◽  
In Vivo Studies ◽  
Low Molecular Weight ◽  
High Molecular Weight Fraction ◽  
Platelet Factor ◽  
Heparin Fractions

SummaryHigh and low molecular weight heparin fractions obtained by gel filtration chromatography of sodium mucosal heparin were injected subcutaneously into six healthy volunteers and compared with the unfractionated substance in a cross-over trial. Equal doses of 5,000 U were administered twice daily over a period of three days and heparin activity was repeatedly controlled before and 2, 4, 8 hrs after injection by means of the APTT, the anti-Xa clotting test and a chromogenic substrate assay. In addition, the in vivo effect of subcutaneously administered fractionated heparin on platelet function was examined on three of the volunteers. The results show that s.c. injections of the low molecular weight fraction induced markedly higher anti-Xa activity than injections of the other preparations. At the same time, APTT results did not significantly differ. Unfractionated heparin and the high molecular weight fraction enhanced ADP-induced platelet aggregation and collagen-mediated MDA production, while the low molecular weight fraction hardly affected these assays, but potently inhibited thrombin-induced MDA production. All heparin preparations stimulated the release of platelet Factor 4 in plasma. During the three-day treatment periods, no side-effects and no significant changes in the response to heparin injections were detected.

Low Molecular Weight Microfibers with Light Sensing Properties

2017 ◽  
Vol 54 (4) ◽  
pp. 655-658
Author(s):  
Andrei Bejan ◽  
Dragos Peptanariu ◽  
Bogdan Chiricuta ◽  
Elena Bicu ◽  
Dalila Belei
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
X Ray Diffraction ◽  
Aromatic Rings ◽  
X Ray ◽  
Force Microscopy ◽  
Light Sensing ◽  
Sensing Applications ◽  
Atomic Force ◽  
Low Molecular Weight Compounds

Microfibers were obtained from organic low molecular weight compounds based on heteroaromatic and aromatic rings connected by aliphatic spacers. The obtaining of microfibers was proved by scanning electron microscopy. The deciphering of the mechanism of microfiber formation has been elucidated by X-ray diffraction, infrared spectroscopy, and atomic force microscopy measurements. By exciting with light of different wavelength, florescence microscopy revealed a specific optical response, recommending these materials for light sensing applications.

scholarly journals Candidate markers for the detection of hepatocellular carcinoma in low-molecular weight fraction of serum

2007 ◽  
Vol 28 (10) ◽  
pp. 2149-2153 ◽  
Author(s):  
Radoslav Goldman ◽  
Habtom W. Ressom ◽  
Mohamed Abdel-Hamid ◽  
Lenka Goldman ◽  
Antai Wang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Molecular Weight ◽  
Weight Fraction ◽  
Low Molecular Weight

Anti-Inflammatory Activity in the Low Molecular Weight Fraction of Commercial Human Serum Albumin (LMWF5A)

2015 ◽  
Vol 37 (1) ◽  
pp. 55-67 ◽  
Author(s):  
Gregory W. Thomas ◽  
Leonard T. Rael ◽  
Charles W. Mains ◽  
Denetta Slone ◽  
Matthew M. Carrick ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Weight Fraction ◽  
Inflammatory Activity ◽  
Low Molecular Weight ◽  
Anti Inflammatory

Characterization of Sol and Gel in Hevea Natural Rubber

1997 ◽  
Vol 70 (5) ◽  
pp. 707-713 ◽  
Author(s):  
Jitladda Tangpakdee ◽  
Yasukuki Tanaka
Keyword(s):  
Molecular Weight ◽  
Weight Fraction ◽  
Toluene Solution ◽  
Low Molecular Weight ◽  
Branch Points ◽  
Gel Content ◽  
High Ammonia ◽  
Linear Molecules ◽  
Cis And Trans

Abstract The gel content of rubber from high-ammonia latex (HA-latex) decreased significantly after deproteinization with proteolytic enzyme. The addition of 1–2% ethanol in toluene solution reduced the gel content of rubbers from HA-latex, deproteinized HA-latex (HA-DP) and pale crepe. Transesterification of the rubber in toluene solution with sodium methoxide dissolved the gel fraction. The gel fractions solubilized after transesterification showed molecular weight distribution rich in low molecular-weight fraction. The Huggins k′ constant of the fractionated rubbers from solubilized-gels was in the range of 0.42–0.45, lower than that of the fractionated HA-DP of 0.5–0.8. This indicates that all the branch-points were decomposed by transesterification to form linear molecules. The Mn values of rubber chains assembling the gel was 5.5−8.3×105 by 13C-NMR measurements of the ratio between cis- and trans-isoprene units, which were comparable to the molecular weight between crosslinks, Mc, of 7−11×105 by swelling measurements. These findings suggest that the branching and crosslinks are composed of two types of branch-points, i. e. one by association or aggregation of proteins or oligopeptides at the initiating end and the other by ester linkages including phosphoric ester at the terminal end.

scholarly journals Antitumor Activities of Low Molecular Weight Fraction Derived from the Cultured Fruit Body of Sparassis crispa in Tumor-Bearing Mice

2007 ◽  
Vol 54 (9) ◽  
pp. 419-423 ◽  
Author(s):  
Kyosuke Yamamoto ◽  
Yoshihiro Nishikawa ◽  
Takashi Kimura ◽  
Munehiko Dombo ◽  
Nariaki Matsuura ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Fruit Body ◽  
Weight Fraction ◽  
Low Molecular Weight ◽  
Antitumor Activities ◽  
Tumor Bearing ◽  
Sparassis Crispa

scholarly journals Low Molecular Weight Gelators Based on Functionalized l-Dopa Promote Organogels Formation

Gels ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 27 ◽  
Author(s):  
Demetra Giuri ◽  
Nicola Zanna ◽  
Claudia Tomasini
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Rheological Properties ◽  
Rhodamine B ◽  
Lauric Acid ◽  
Water Solution ◽  
Preliminary Test ◽  
Low Molecular Weight ◽  
Coupling Reactions ◽  
Low Molecular Weight Gelators

We prepared the small pseudopeptide Lau-l-Dopa(OBn)2-d-Oxd-OBn (Lau = lauric acid; l-Dopa = l-3,4-dihydroxyphenylalanine; d-Oxd = (4R,5S)-4-methyl-5-carboxyl-oxazolidin-2-one; Bn = benzyl) through a number of coupling reactions between lauric acid, protected l-Dopa and d-Oxd with an excellent overall yield. The ability of the product to form supramolecular organogels has been tested with different organic solvents of increasing polarity and compared with the results obtained with the small pseudopeptide Fmoc-l-Dopa(OBn)2-d-Oxd-OBn. The mechanical and rheological properties of the organogels demonstrated solvent-dependent properties, with a storage modulus of 82 kPa for the ethanol organogel. Finally, to have a preliminary test of the organogels’ ability to adsorb pollutants, we treated a sample of the ethanol organogel with an aqueous solution of Rhodamine B (RhB) for 24 h. The water solution slowly lost its pink color, which became trapped in the organogel.

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