Physicochemical properties of sodium lignosulfonates (NaLS) modified by laccase

Holzforschung ◽  
2012 ◽  
Vol 66 (7) ◽  
pp. 825-832 ◽  
Author(s):  
Haifeng Zhou ◽  
Dongjie Yang ◽  
Xiaolei Wu ◽  
Yonghong Deng ◽  
Xueqing Qiu
Keyword(s):  
Surface Tension ◽  
Physicochemical Properties ◽  
Opposite Effect ◽  
Adsorption Process ◽  
Gel Permeation Chromatography ◽  
Sodium Lignosulfonate ◽  
Substitution Pattern ◽  
Cement Pastes ◽  
Gel Permeation ◽  
Initial Decrease

Abstract The ability of commercial laccase for improvement of the physicochemical properties of sodium lignosulfonate (NaLS) without any mediator has been investigated. Surface tension, adsorption characteristics, rheological behaviors and fluidity of cement pastes were in focus. Gel permeation chromatography (GPC) shows an initial decrease and then an extensive increase of molecular weight (MW) of NaLS after incubation with laccase. Parallel to MW decrement, the content of phenolic groups is increasing, while an MW increment has the opposite effect. The UV-Vis spectra and the zeta potential of NaLS do not indicate further modification of the substitution pattern on the aromatic ring. The surface tension of NaLS and the adsorbed amount of NaLS on MgO particles is elevated after laccase treatment. The electrostatic attraction between MgO particles and NaLS is the main driving force during this adsorption process. The dispersion efficiency of laccase modified NaLS on the MgO slurry and cement paste is improved.

The Influence of Laccase Modification on the Adsorption of Lignosulfonate

2012 ◽  
Vol 550-553 ◽  
pp. 1266-1269
Author(s):  
Hai Feng Zhou ◽  
Dong Jie Yang ◽  
Meng Xian Bai ◽  
Xue Qing Qiu
Keyword(s):  
Self Assembly ◽  
Gel Permeation Chromatography ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Groups ◽  
Mean Square ◽  
Sodium Lignosulfonate ◽  
Gel Permeation ◽  
Initial Decrease ◽  
Assembly Technology ◽  
Phenolic Hydroxyl Groups

The ability of commercial laccase to improve the adsorption of sodium lignosulfonate (SL) without any mediator was studied. When SL are modified by laccase, gel permeation chromatography (GPC) shows an initial decrease followed by an extensive increase in molecular weight (Mw). Furthermore, the decrease in Mw is accompanied by an increase in phenolic hydroxyl groups, while the increase in Mw is accompanied by the decrease in phenolic hydroxyl groups. The laccase modification does not affect the content of the sulfonic group. Furthermore, the electrostatic self-assembly technology indicates that the adsorbed amount and the root-mean-square (RMS) of SL/PDAC multilayers increase obviously with the increase of the incubation time, which might be due to the influence of the Mw and the adsorption configuration.

Effects of the Carboxyl Density on the Properties of Polycarboxylate-Type Superplasticizer

2014 ◽  
Vol 989-994 ◽  
pp. 151-155
Author(s):  
Cheng Fei Fu ◽  
Guang Jun Zheng ◽  
Kang Ling Li ◽  
Yao Bi ◽  
Long Xiong
Keyword(s):  
Molecular Weight ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Acrylic Acid ◽  
Weight Distribution ◽  
High Performance ◽  
Gel Permeation Chromatography ◽  
Monomer Conversion ◽  
Cement Pastes ◽  
Gel Permeation

The effect of carboxyl density (the ratio of acrylic acid and polyoxyethylene ether) upon the performance, molecular weight, and monomer conversion rate of polycarboxylate (PCE) were investigated by slump test, Gel Permeation Chromatography (GPC) and High Performance Liquid Chromatography (HPLC), respectively. The results showed that with carboxyl density increased from 2:1 to 7:1, molecular weight of PCE increased from 7968.5 to 13930.1 and the molecular weight distribution coefficient increased from 1.5 to 2. The HPLC date indicated carboxyl density does not affect the rate of monomer conversion. Test of the fluidity of cement pastes displayed that as carboxyl density was 4.0:1, PCE show the optimal dispersion and dispersion-retaining ability.

Effect of Sodium Methylacrysulfonate upon the Molecular Weight and Performance of Polycarboxylate Superplasticizer

2014 ◽  
Vol 989-994 ◽  
pp. 91-96
Author(s):  
Long Xiong ◽  
Guang Jun Zheng ◽  
Yao Bi ◽  
Cheng Fei Fu ◽  
Shao Feng Wang
Keyword(s):  
Molecular Weight ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Gel Permeation Chromatography ◽  
Monomer Conversion ◽  
Cement Pastes ◽  
Cubic Equation ◽  
Gel Permeation ◽  
And Performance

The effect of sodium methylacrysulfonate (SMAS) upon the molecular weight, molecular weight distribution and polycarboxylate (PCE)’s dispersion and dispersion-retaining ability were investigated by Gel permeation chromatography (GPC) and test of the fluidity of cement pastes. The results showed that the dosage of SMAS was inversely proportional to the molecular weight of polycarboxylate, and a cubic equation relationship existed between the molecular weight of the polycarboxylate and the reciprocal of SMAS dosage. There was an optimum middle dosage of sodium methylacrysulfonate which could control the molecular weight polycarboxylate, and then affect its dispersion and dispersion maintain performance. The effect of sodium methylacrysulfonate on the monomer conversion rate was also systematically discussed by means of high performance liquid chromatography (HPLC).

Aggregated, Conformationally Changed Fibrinogen Exposes the Stimulating Sites for t-PA-Catalysed Plasminogen Activation

1996 ◽  
Vol 75 (02) ◽  
pp. 326-331 ◽  
Author(s):  
Unni Haddeland ◽  
Knut Sletten ◽  
Anne Bennick ◽  
Willem Nieuwenhuizen ◽  
Frank Brosstad
Keyword(s):  
Conformational Changes ◽  
Gel Permeation Chromatography ◽  
Tissue Type ◽  
Plasminogen Activation ◽  
Chromogenic Substrate ◽  
Type Plasminogen Activator ◽  
Gel Permeation ◽  
Self Association ◽  
Fibrin Monomers ◽  
Stimulation Of

SummaryThe present paper shows that conformationally changed fibrinogen can expose the sites Aα-(148-160) and γ-(312-324) involved in stimulation of the tissue-type plasminogen activator (t-PA)-catalysed plasminogen activation. The exposure of the stimulating sites was determined by ELISA using mABs directed to these sites, and was shown to coincide with stimulation of t-PA-catalysed plasminogen activation as assessed in an assay using a chromogenic substrate for plasmin. Gel permeation chromatography of fibrinogen conformationally changed by heat (46.5° C for 25 min) demonstrated the presence of both aggregated and monomeric fibrinogen. The aggregated fibrinogen, but not the monomeric fibrinogen, had exposed the epitopes Aα-(148-160) and γ-(312-324) involved in t-PA-stimulation. Fibrinogen subjected to heat in the presence of 3 mM of the tetrapeptide GPRP neither aggregates nor exposes the rate-enhancing sites. Thus, aggregation and exposure of t-PA-stimulating sites in fibrinogen seem to be related phenomena, and it is tempting to believe that the exposure of stimulating sites is a consequence of the conformational changes that occur during aggregation, or self-association. Fibrin monomers kept in a monomeric state by a final GPRP concentration of 3 mM do not expose the epitopes Aα-(148-160) and γ-(312-324) involved in t-PA-stimulation, whereas dilution of GPRP to a concentration that is no longer anti-polymerizing, results in exposure of these sites. Consequently, the exposure of t-PA-stimulating sites in fibrin as well is due to the conformational changes that occur during selfassociation.

Gel Permeation Chromatography of Polyelectrolytes

1981 ◽  
Vol 4 (8) ◽  
pp. 1297-1309 ◽  
Author(s):  
M. Rinaudo ◽  
J. Desbrières ◽  
C. Rochas
Keyword(s):  
Gel Permeation Chromatography ◽  
Gel Permeation
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