Diffusion Behavior of Humic Acid in Compacted Bentonite: Effect of Ionic Strength, Dry Density and Molecular Weight of Humic Acid

ABSTRACTThe apparent diffusivities (Da) and activation enthalpies (ΔEa) for I− and Cs+ ions in compacted Na-smectite were obtained in the parallel and perpendicular directions to the orientation of smectite particles as a function of smectite's dry density (0.9-1.4 Mg/m3), salinity ([NaCl]=0.01, 0.51 M) and temperature (295-333 K). The Da-values for both ions tended to be higher in the parallel direction than in the perpendicular direction to the orientation of smectite particles. The Da-values of I− ions in the parallel direction decreased with increasing salinity only at low dry density, but those of Cs+ ions increased with increasing salinity for all conditions. Based on this, it is interpreted that I− ions predominantly diffuse in external pores and Cs+ ions diffuse in both interlayer and external pores. The ΔEa-values forI− ions are at similar levels as those for the ionic diffusivity in free water (D°) of I− ions at low dry density and increased with increasing dry density. The ΔEa-values for Cs+ ions are higher than those for the D° of Cs+ ions even at low dry density and increased with increasing dry density. Such high ΔEa-values for Cs+ ions are considered to be due to the combined effects of the ion exchange enthalpy between Cs+ and Na+ ions in smectite and the lowering in the activity of porewater.

Download Full-text

Effects of the Orientation of Clay Particles and Ionic Strength on Diffusion and Activation Enthalpies of I−and Cs+ Ions in Compacted Bentonite

MRS Proceedings ◽

10.1557/proc-824-cc8.46 ◽

2004 ◽

Vol 824 ◽

Cited By ~ 1

Author(s):

Haruo Sato

Keyword(s):

Ionic Strength ◽

Free Water ◽

Interlayer Distance ◽

Perpendicular Direction ◽

Dry Density ◽

Clay Particles ◽

Compacted Bentonite ◽

Parallel Direction ◽

Cs Ions ◽

And Diffusion

AbstractApparent diffusivities (Da) for I− and Cs+ in compacted Na-smectite were studied as a function of smectite's dry density (0.9–1.4 Mg/m3, ionic strength (IS: [NaCl]=0.01, 0.51 M), temperature (22–60 °C) and diffusion directionto the orientated direction of smectite particles. The Da-values for both ions in parallel direction to the orientated direction showed a tendency to be higher than those in the perpendicular direction at lowIS. The Da-values for I− showed different trends depending on diffusion direction and dry density at high IS, but Da-values for Cs+ increased with increasing IS in both diffusion directions. The activation enthalpies (ΔEa) for I−, slightly higher than that of diffusivity in free water (Do) at low IS, similar level to that of Do at high IS, increased with increasing dry density. While, ΔEa-values for Cs+, clearly higher than that of Do for all conditions, increased with increasing dry density. Since it is known that interlayer distance depends on both dry density and IS, diffusive pathway is considered to differ depending on the charge of diffusion species.

Download Full-text

Antithrombin III Binding to Surface Immobilized Heparin and Its Relation to F Xa Inhibition

Thrombosis and Haemostasis ◽

10.1055/s-0038-1646057 ◽

1987 ◽

Vol 58 (04) ◽

pp. 1064-1067 ◽

Cited By ~ 41

Author(s):

K Kodama ◽

B Pasche ◽

P Olsson ◽

J Swedenborg ◽

L Adolfsson ◽

...

Keyword(s):

Molecular Weight ◽

Ionic Strength ◽

Surface Coating ◽

Antithrombin Iii ◽

Lower Class ◽

Biologically Active ◽

High Affinity ◽

Heparin Coating ◽

Continuous Surface ◽

Approximate Molecular Weight

SummaryThe mode of F Xa inhibition was investigated on a thromboresistant surface with end-point attached partially depoly-merized heparin of an approximate molecular weight of 8000. Affinity chromatography revealed that one fourth of the heparin used in surface coating had high affinity for antithrombin III (AT). The heparin surface adsorbed AT from both human plasma and solutions of purified AT. By increasing the ionic strength in the AT solution the existence of high and low affinity sites could be shown. The uptake of AT was measured and the density of available high and low affinity sites was found to be in the range of 5 HTid 11 pic.omoles/cmf, respectively Thus the estimated density of biologically active high and low ailmity heparm respectively would be 40 and 90 ng/cm2 The heparin coating did not take up or exert F Xa inhibition by itself. With AT adsorbed on both high and low affinity heparin the surface had the capacity to inhibit several consecutive aliquots of F Xa exposed to the surface. When mainly high affinity sites were saturated with AT the inhibition capacity was considerably lower. Tt was demonstrated that the density of AT on both high and low affinity heparin determines the F Xa inhibition capacity whereas the amount of AT on high affinity sites limits the rate of the reaction. This implies that during the inhibition of F Xa there is a continuous surface-diffusion of AT from sites of a lower class to the high affinity sites where the F Xa/AT complex is formed and leaves the surface. The ability of the immobilized heparin to catalyze inhibition of F Xa is likely to be an important component for the thromboresistant properties of a heparin coating with non-compromized AT binding sequences.

Download Full-text

Interaction of Plasminogen Activators and Plasminogen with Heparin: Effect of Ionic Strength

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649685 ◽

1993 ◽

Vol 70 (05) ◽

pp. 867-872 ◽

Cited By ~ 21

Author(s):

Dingeman C Rijken ◽

Gerard A W de Munk ◽

Annie F H Jie

Keyword(s):

Molecular Weight ◽

Ionic Strength ◽

Plasminogen Activator ◽

Plasminogen Activators ◽

Fibrinolytic System ◽

Tissue Type ◽

Single Chain ◽

Physiological Conditions ◽

Amino Terminal ◽

Type Plasminogen Activator

SummaryIn order to define the possible effects of heparin on the fibrinolytic system under physiological conditions, we studied the interactions of this drug with plasminogen and its activators at various ionic strengths. As reported in recent literature, heparin stimulated the activation of Lys-plasminogen by high molecular weight (HMW) and low molecular weight (LMW) two-chain urokinase-type plasminogen activator (u-PA) and two-chain tissue-type plasminogen activator (t-PA) 10- to 17-fold. Our results showed, however, that this stimulation only occurred at low ionic strength and was negligible at a physiological salt concentration. Direct binding studies were performed using heparin-agarose column chromatography. The interaction between heparin and Lys-plasminogen appeared to be salt sensitive, which explains at least in part why heparin did not stimulate plasminogen activation at 0.15 M NaCl. The binding of u-PA and t-PA to heparinagarose was less salt sensitive. Results were consistent with heparin binding sites on both LMW u-PA and the amino-terminal part of HMW u-PA. Single-chain t-PA bound more avidly than two-chain t-PA. The interactions between heparin and plasminogen activators can occur under physiological conditions and may modulate the fibrinolytic system.

Download Full-text

Antiheparin Activity of Human Serum and Platelet Factor 4

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649105 ◽

1973 ◽

Vol 30 (01) ◽

pp. 093-105 ◽

Cited By ~ 1

Author(s):

C.H.J Sear ◽

L Poller ◽

F.R.C Path

Keyword(s):

Molecular Weight ◽

Ionic Strength ◽

Blood Serum ◽

Whole Blood ◽

Platelet Rich Plasma ◽

Gel Filtration ◽

Normal Serum ◽

Platelet Factor ◽

Mean Values ◽

Antiheparin Activity

SummaryThe antiheparin activity of normal serum has been studied by comparing the antiheparin activities of sera obtained from normal whole blood, platelet-rich plasma and platelet-’free’ plasma with a purified platelet extract during differential isoelectric precipitation and by gel filtration chromatography.The mean values for the activity of PRP-serum and PFP-serum were 106% (S.D. 11) and 10% (S.D. 3) of untreated whole blood respectively. The activity of whole blood serum, PRP serum and whole blood serum plus platelet extract precipitated under identical physical conditions, i.e. pH 7.0, I =0.008, indicating that the activities of the three samples are probably associated with PF4. PF4 precipitated from human platelet extract at pH 4.0, but this is probably due to the difference in the two biochemical environments investigated, i.e. serum and platelet extract.The gel filtration experiments revealed striking similarities between the major antiheparin activities of serum and platelet extract. At physiological pH and ionic strength both activities were associated with high molecular weight material, but at physiological pH and elevated ionic strength both activities behaved as much smaller entities of molecular weight between 25,000 and 30,000 daltons and it seems very likely that both activities are associated with the same molecule, i.e. PF4.

Download Full-text

Characteristics of fouling due to clay-organic substances in potable water treatment by ultrafiltration

Water Science & Technology ◽

10.2166/wst.1996.0201 ◽

1996 ◽

Vol 34 (9) ◽

pp. 157-164 ◽

Cited By ~ 2

Author(s):

Kim C.-H. ◽

M. Hosomi ◽

A. Murakami ◽

M. Okada

Keyword(s):

Molecular Weight ◽

Organic Matter ◽

Humic Acid ◽

Fulvic Acid ◽

Size Distribution ◽

Ultrafiltration Membrane ◽

Organic Substances ◽

Decomposition Products ◽

Microbial Decomposition ◽

Fouling Materials

Effects of clay on fouling due to organic substances and clay were evaluated by model fouling materials and kaolin. Model fouling materials selected were protein, polysaccharide, fulvic acid, humic acid and algogenic matter (EOM:ectracellular organic matter, microbial decomposition products) and kaolin was selected as the clay material. Polysulfone membrane (MWCO(Molecular Weight Cut-Off) 10,000, 50,000 and 200,000) was used as an ultrafiltration membrane. In particular, the flux measurement of solutions containing algogenic matter used an ultrafiltration membrane of MWCO 50,000. The flux of protein and polysaccharide with coexistence of kaolin increased in the case of the ratio of MW/MWCO being greater than one, but did not increase in the case of the MW/MWCO ratio being below one. In contrast, the flux of fulvic acid and humic acid with coextence of kaolin decreased regardless of the ratio of MW/MWCO. The addition of dispersion agent and coagulant in the organic substances and kaolin mixture solution changed the size distribution of kaolin, and resulted in a change of the flux. EOM and microbial decomposition products decreased with the increase of the fraction of organic matter having molecular weight more than MWCO of membrane. The flux of the algogenic organic matter with coexistence of kaolin decreased with the increase of the amount of kaolin. It was suggested that the decline of the flux with coexistence of kaolin was due to the change of the resistance of the kaolin cake layer corresponding to the change in kaolin size distribution with charge.

Download Full-text