PHYSICOCHEMICAL STUDIES OF LIGNINSULPHONATES: I. PREPARATION AND PROPERTIES OF FRACTIONATED SAMPLES

1955 ◽  
Vol 33 (10) ◽  
pp. 1477-1490 ◽  
Author(s):  
J. L. Gardon ◽  
S. G. Mason
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficients ◽  
Distribution Curve ◽  
Distilled Water ◽  
Continuous Analysis ◽  
Neutralization Equivalent ◽  
Molecular Weights ◽  
Spent Sulphite Liquor ◽  
Physicochemical Studies ◽  
Molecular Weight Distribution Curve

High molecular weight ligninsulphonates were separated from other constituents of spent sulphite liquor by a method of dialysis allowing continuous removal of the dialyzates and their replacement by distilled water. The process was controlled by continuous analysis of the residue and dialyzate. The lower molecular weight ligninsulphonates in the dialyzates were separated from the carbohydrates by precipitating their barium salts with ethanol; four fractions corresponding to different times of dialysis were prepared in this manner. The ligninsulphonates in the dialyzed liquor were separated into four additional fractions by ultrafiltration through membranes of different pore sizes. The methoxyl, sulphur, and phenolic hydroxyl contents, neutralization equivalent weights, reducing powers, ultraviolet absorption spectra, diffusion coefficients, and number-average molecular weights of the eight fractions were determined. The molecular weights of the fractions range from 3700 to 58,000 but the integral molecular weight distribution curve indicates the presence of ligninsulphonates with molecular weights as high as 100,000.

scholarly journals Sedimentation-equilibrium studies on the heterogeneity of two β-lactamases

1970 ◽  
Vol 118 (3) ◽  
pp. 467-474 ◽  
Author(s):  
P. H. Lloyd ◽  
A. R. Peacocke
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficients ◽  
Minor Component ◽  
Theoretical Solution ◽  
Sedimentation Equilibrium ◽  
Equilibrium Studies ◽  
Molecular Weights ◽  
A Minor

Solutions of crystalline β-lactamase I and β-lactamase II, prepared by Kuwabara (1970), were examined in the ultracentrifuge and their sedimentation coefficients, diffusion coefficients, molecular weights and heterogeneity determined. Each sample was shown to consist of a major component comprising at least 97% of the material and a minor component of much higher molecular weight. The molecular weights of the major components were 27800 for β-lactamase I and 35600 for β-lactamase II. Emphasis is placed on a straightforward practical way of analysing the sedimentation-equilibrium results on mixtures of two macromolecular components rather than on a strict theoretical solution. Appendices describe the theory of systems at both chemical and sedimentation equilibrium and the procedure for calculating the combined distribution of two components.

The Structure of Neoprene. I. The Molecular-Weight Distribution of Neoprene Type GN

1949 ◽  
Vol 22 (3) ◽  
pp. 680-689
Author(s):  
W. E. Mochel ◽  
J. B. Nichols ◽  
C. J. Mighton
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Osmotic Pressure ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Distribution Curve ◽  
Pressure Measurements ◽  
Dilute Solution ◽  
Molecular Weights ◽  
Good Agreement

Abstract Polychloroprene rubber (Neoprene Type GN) was fractionated by partial precipitation from dilute solution in benzene and the fractions were examined both osmotically and viscometrically in benzene solutions. The molecular-weight distribution curve for Neoprene Type GN based on osmotic pressure measurements shows a pronounced maximum at 100,000, but has a long extension to molecular weights of over one million, indicating the presence of branched or cross-linked material which is still soluble. The uniformity is somewhat less than that of sol natural rubber, while in shape the Neoprene distribution curve resembles more closely that of peptized natural rubber than fresh sol rubber. Observed variations in the slopes of the π/c vs. c and the ηsp/c vs. c curves also indicate the presence in solution of complex, branched and (or) cross-linked molecules. Calibration of the intrinsic viscosity-molecular weight relationship by osmotic pressure measurements gave good agreement with the equation: [η]=KMa, where K=1.46×10−4 and a=0.73.

Gel Permeation Chromatography of Natural Rubber

1972 ◽  
Vol 45 (1) ◽  
pp. 346-358 ◽  
Author(s):  
A. Subramaniam
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Weight Distribution ◽  
Hevea Brasiliensis ◽  
Distribution Curve ◽  
Gel Permeation Chromatography ◽  
Bimodal Distribution ◽  
Fractional Precipitation ◽  
Molecular Weights ◽  
Gel Permeation

Abstract The Waters Model 200 Gel Permeation Chromatograph has been used to study the molecular weight distribution of natural rubber. The cumulative weight distribution curve of synthetic cis-polyisoprene from the GPC method showed fair agreement with the distribution obtained by fractional precipitation. For natural rubber the agreement was not so good. Natural rubber samples from six clones of Hevea Brasiliensis were examined with the GPC. Differences were observed in their distributions. Five clones showed a distinct bimodal distribution. The weight and number average molecular weights from the GPC were found to be too low. Some possible reasons for this have been suggested.

Gastrin peptide isolation in broiler chicken

2015 ◽  
Author(s):  
A. K. Mandal ◽  
R. K. Das ◽  
A. Maity ◽  
G. R. Sahoo
Keyword(s):  
Molecular Weight ◽  
Broiler Chicken ◽  
Electrophoretic Analysis ◽  
Distilled Water ◽  
Protein Marker ◽  
Molecular Weights ◽  
Sds Page ◽  
Reference Protein ◽  
Relative Molecular Weight

The present study was undertaken to isolate gastrin peptide from the antral tissue of broiler chicken. The chicken antrums, i.e. tissue pieces from a narrow zone at gizzard – duodenal junction were collected, boiled in distilled water, followed by centrifugation at 0° C. The supernatant was collected, added to isopropanol and stirred overnight. After addition of dichloromethane, the aqueous phase was partitioned, aspirated and lyophilized. The electrophoretic analysis (SDS-PAGE) of the antral sample was carried out after running it along with a reference protein marker. Characterization of the antral extract revealed a total of eleven peptide bands having relative molecular weights (Mr) ranging from 4.6 to114.5 kDa, out of which peptides having Mr of 22.6 and 26.3 kDa were major ones. The protein or peptide band showing the lowest relative molecular weight (Mr, 4.6 kDa) was identified as the gastrin.

Assoziationsverhalten von T2-Lysozym

1964 ◽  
Vol 19 (3) ◽  
pp. 230-234 ◽  
Author(s):  
K. Wagner ◽  
W. Katz
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficients ◽  
Egg White ◽  
Molecular Weights ◽  
Egg White Lysozyme ◽  
Equilibrium Method ◽  
Ph Dependent ◽  
Reversible Association ◽  
And Diffusion

Particle-bound T 2 phage lysozyme and lysozyme from T 2 phage lysates are compared with each other by ultracentrifugation. The molecular weights determined by an equilibrium method and by sedimentation and diffusion coefficients are identical within the error of estimation.Similar to egg-white lysozyme, T 2 phage lysozyme shows a pH-dependent, reversible association.The value of the molecular weight obtained at pH 5.1 is 13 900.

MOLECULAR WEIGHT AND HYDRODYNAMIC PROPERTIES OF SODIUM ALGINATE

1954 ◽  
Vol 32 (3) ◽  
pp. 227-239 ◽  
Author(s):  
W. H. Cook ◽  
David B. Smith
Keyword(s):  
Molecular Weight ◽  
Sodium Alginate ◽  
Intrinsic Viscosity ◽  
Diffusion Coefficients ◽  
Linear Relation ◽  
Hydrodynamic Properties ◽  
Viscosity Measurements ◽  
Molecular Weights ◽  
Extension Ratio ◽  
Good Agreement

Sedimentation, diffusion, and viscosity measurements were made on five unfractionated samples of sodium alginate ranging in intrinsic viscosity from 3.1 to 17.5. Diffusion coefficients were subject to large errors and are believed to be overestimated.Though the molecular weights obtained from sedimentation–diffusion (Svedberg equation) and sedimentation – intrinsic viscosity (Perrin–Simha equations) showed good agreement and yielded values of 3 to 21 × 104, higher values (4.6 to 37 × 104) from sedimentation–viscosity (Mandelkern–Flory equation) appear to be the better estimates. A linear relation between intrinsic viscosity and molecular weight was found with a slope (Mandelkern–Flory equation values) equivalent to Km = 13.9 × 10−3. The results indicate that sodium alginate has a relatively high extension ratio.

scholarly journals Molecular-mass distribution of humus acids of taiga soils

2021 ◽  
Vol 4 (4) ◽  
Author(s):  
E. D. Lodygin ◽  
R. S. Vasilevich
Keyword(s):  
Molecular Weight ◽  
Molecular Mass ◽  
Molecular Mass Distribution ◽  
Weight Fraction ◽  
Low Molecular Weight ◽  
Distilled Water ◽  
High Molecular Weight Fraction ◽  
Molecular Weights ◽  
Podzolic Horizon ◽  
Agricultural Use

Purpose of the study: to reveal the influence of hydromorphism and agricultural use on the molecular-mass distribution (MMD) of humic (HAs) and fulvic acids (FAs) isolated from the soils of the European northeast of Russia. To assess the influence of the acidity of the medium on the MWD of FAs. Place and time of the event. The studies were carried out on the territory of the middle taiga (Maksimovsky station of the Institute of Biology of the Federal Research Center of the KSC UB RAS, located 8 km west of the city of Syktyvkar and the field of the Syktyvkar state farm, 5 km south-west of Syktyvkar, on the watershed of the Sysola and Vazhel-yu rivers) and northern taiga (3 km west of the Troitsko-Pechorsk station). The objects of the study were humic substances isolated from typical podzolic (Eutric Albic Retisol (Loamic)), gleypodzolic (Eutric Albic Stagnic Retisol (Loamic)), peaty-podzolic surface-gleyed (Eutric Albic Stagnic Histic) Retisol (Loamic Eutric Albic Retisol (Loamic)) soils. The soil sampling period is from 1 to 30 August 2014. Methodology. Quantitative analysis of the MMD of HA and FA preparations was performed using liquid size exclusion chromatography (gel chromatography) on Sephadex G-25 and G-100 gels with continuous automatic registration of the optical density of the eluate (λ = 280 nm) in a quartz flow cell, K 9 × 60 cm column (Pharmacia, Sweden). Distilled water, 0.05 M NaOH solution, and Tris-HCl buffer with pH = 8.2 were used as the eluent. Main results. Studies of the MMD of humic substances have been carried out. It was found that HAs contain three fractions with different molecular weights: ≥ 150 kDa, 73–80 kDa, and 13–23 kDa; FAs – two fractions: ≥ 5 kDa, 1–2 kDa. The low molecular weight of FAs, together with a large amount of oxygen-containing functional groups, contributes to their better solubility and migration ability in soils. The HAs of automorphic soils are characterized by a high content of low molecular weight fractions, and the proportion of the high molecular weight fraction in the HAs of the litter is 1.5–2.0 times higher than in the HAs of the podzolic horizon, which may be due to the migration of the low molecular weight fraction down the profile. The high proportion of the acidic low molecular weight fraction in the podzolic horizon promotes the decomposition of soil minerals and their leaching into the illuvial horizon. The influence of agricultural use of soils on the fractional composition of humic compounds is estimated. A sharp increase in the share of the high molecular weight fraction in the preparations of HAs of arable podzolic soil by 2–4 times compared with the HAs of virgin podzolic soils was noted, which is due to the cultivation of the arable horizon, the nature of the incoming plant residues and the increased microbiological activity of the developed soils. The effect of acidity of the medium on the character of chromatograms of FA preparations isolated from the main types of soils of the Komi Republic was studied. It has been shown that in the region of high pH values of the eluent 9–13, the absence of fractionation is associated with the association of FAs, a change in their conformation, and the effect of “over-exclusion”. Elution with distilled water (pH = 6.5) allows the separation of FAs into two fractions with molecular weights ≥ 5 kDa and 1–2 kDa.

MOLECULAR WEIGHT AND HYDRODYNAMIC PROPERTIES OF SODIUM ALGINATE

1954 ◽  
Vol 32 (1) ◽  
pp. 227-239 ◽  
Author(s):  
W. H. Cook ◽  
David B. Smith
Keyword(s):  
Molecular Weight ◽  
Sodium Alginate ◽  
Intrinsic Viscosity ◽  
Diffusion Coefficients ◽  
Linear Relation ◽  
Hydrodynamic Properties ◽  
Viscosity Measurements ◽  
Molecular Weights ◽  
Extension Ratio ◽  
Good Agreement

Sedimentation, diffusion, and viscosity measurements were made on five unfractionated samples of sodium alginate ranging in intrinsic viscosity from 3.1 to 17.5. Diffusion coefficients were subject to large errors and are believed to be overestimated.Though the molecular weights obtained from sedimentation–diffusion (Svedberg equation) and sedimentation – intrinsic viscosity (Perrin–Simha equations) showed good agreement and yielded values of 3 to 21 × 104, higher values (4.6 to 37 × 104) from sedimentation–viscosity (Mandelkern–Flory equation) appear to be the better estimates. A linear relation between intrinsic viscosity and molecular weight was found with a slope (Mandelkern–Flory equation values) equivalent to Km = 13.9 × 10−3. The results indicate that sodium alginate has a relatively high extension ratio.

PHYSICOCHEMICAL STUDIES OF ALKALI LIGNINS: III. SIZE AND SHAPE OF THE MACROMOLECULE

1960 ◽  
Vol 38 (2) ◽  
pp. 270-279 ◽  
Author(s):  
P. R. Gupta ◽  
D. A. I. Goring
Keyword(s):  
Molecular Weight ◽  
Sedimentation Coefficient ◽  
Random Coil ◽  
Alkali Lignin ◽  
Molecular Weights ◽  
A Value ◽  
Huggins Constant ◽  
Physicochemical Studies ◽  
Lignin Macromolecule ◽  
Very High

Light-scattering measurements were made on the alkali lignin fractions described in a previous paper. The range of molecular weights found was from 50,000 to 48 × 106. The usual logarithmic graph of intrinsic viscosity and molecular weight was linear and gave a value of 0.32 for the exponent. From the logarithmic sedimentation coefficient – molecular weight relationship, the exponent was found as 0.52. Flory's hydrodynamic parameter [Formula: see text] was 2.3 × 106. These results suggested that the configuration of the alkali lignin macromolecule conformed to a structure between that of a random coil and an Einstein's sphere impenetrable to solvent. The branching parameter, g, introduced by Zimm and Stockmayer, decreased with an increase in molecular weight as expected. Most of the values of Huggins' constant, k′,were between 1 and 2 which indicated a compact particle. A marked increase in k′ was noted for fractions of low or very high molecular weight. The significance of the data is discussed and a model tentatively suggested for the macromolecule.

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.

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