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Ion Strength (ion + strength)
Selected AbstractsA study in the uranyl ions uptake on acrylic acid and acrylamide copolymeric hydrogelsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Ghanshyam S. Chauhan Abstract A series of copolymeric hydrogels comprising of acrylic acid and acrylamide and crosslinked with trimethylolpropane triacrylate (TMPTA) were prepared using ammonium persulfate (APS) as initiator. The hydrogels were functionalized further by partial hydrolysis and were characterized by SEM, FTIR, nitrogen analysis, and also by water uptake studies as a function of time, temperature, pH, NaCl, and concentration of sodium dodecyl sulfate (SDS). These hydrogels were used as sorbents for the uranyl ions uptake in the presence of 5% NaCl, which was studied as function of time, temperature, pH, and ion strength. The uranyl uptake was found to be affected both by the structural aspects of the hydrogels as well as by the external environmental factors. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] A study on the sorption of NO3, and F, on the carboxymethylated starch-based hydrogels loaded with Fe2+ ionsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Ghanshyam S. Chauhan Abstract Using the principle of geochemistry of fluoride, green and cost effective anion adsorbents were developed for the removal of F, from water systems. The scheme was further applied for the removal of NO3, also. Carboxymethylated starch functionalized through network formation with acrylamide was used as adsorbent, and the resultant hydrogels were loaded with Fe2+ ions to generate anchorage for the anions. Sorption of Fe2+ was studied as a function of different factors such as time, temperature, pH, and ion strength. The network having the highest Fe2+ uptake was loaded with the Fe2+ ions under optimum conditions and used for the sorption of F, and NO3,. High efficiency has been observed for F,, as even up to 100% uptake has been observed within just 10 minutes. The support shows high selectivity for NO3,, which was used as anion reference. Thermodynamics of sorption confirms low order and low energy processes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Ion-pair mediated transport of small model peptides in liquid phase micro extraction under acidic conditionsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 3 2005J. Léon E. Reubsaet Abstract This paper discusses the behaviour of five small model peptides in a three phase (aqueous donor-organic-aqueous acceptor) liquid phase micro extraction system in relation to their physico-chemical properties (charge, hydrophobicity). It is proved that for all peptides transport over the organic phase is mediated by aliphatic sulphonic acids. Heptane-1-sulphonic acid gave the best overall recoveries. It appeared that peptides with hydrophobic properties (IPI) and a high number of positive charges (KYK) show good recoveries and are enriched in the acceptor phase. Variation in the pH (1.6,4.4) of the donor phase shows that there are peptide-dependent optimal pH-values for their recovery. Increasing pH in the acceptor phase shows that in most cases the recovery decreases due to decreased ion-pair mediated membrane transport. For KYK the partition between the organic phase and the aqueous acceptor-phase is also driven by the solubility in the aqueous acceptor phase. Increase of the ion strength of the acceptor phase did not affect the recovery of the peptides. Except for KYK, which showed decreased recovery when the ion strength increased. Another finding is that delocalisation of positive charge causes bad recovery, probably due to incomplete ion-pair-peptide complex formation. [source] The efficient and specific isolation of the antibodies from human serum by thiophilic paramagnetic polymer nanospheresBIOTECHNOLOGY PROGRESS, Issue 2 2009Hao Qian Abstract A rapid and effective method to specifically isolate the antibodies from human serum was presented based on the fast magnetic separation and specific adsorption of the novel thiophilic magnetic polymer nanospheres, which were synthesized by using miniemulsion copolymerization. After the thiophilic heterocyclic ligands of 2-mercaptonicotinic acid were first activated via divinyl sulfone, they were immobilized on the surface of these magnetic nanospheres, through which the strong specificity to immunoglobulin G was evidently expressed in the isolation of antibodies from human serum. The mild conditions used in the process, including the physiological pH range, low temperature, and low ion strength, were so favorable for keeping the biological activity of antibodies, which resulted in their bioactivity purity to exceed 99%. The efficient isolation, simplicity process, mild conditions, and the conventional equipments required make this technology so attractive to purify antibodies from human serum. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Peptide Recognition: Encapsulation and ,-Helical Folding of a Nine-Residue Peptide within a Hydrophobic Dimeric Capsule of a Bowl-Shaped HostCHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2006Shohei Tashiro Abstract A dimeric capsule of coordination bowl 1 encapsulated a nine-residue peptide (Trp-Ala-Glu-Ala-Ala-Ala-Glu-Ala-Trp; 2) within the large hydrophobic cavity in water, and stabilized the ,-helical conformation of bound 2. An NMR titration experiment revealed that monomeric bowl 1 recognized two Trp residues at the both terminals of 2 through 1/2=1:1 to 2:1 complexation. The 1:1 and 2:1 species exist in equilibrium even in the presence of excess 1. It was found that the formation of the 2:1 complex, in which two bowls of 1 wrapped the whole of 2, became dominant by the addition of NaNO3 due to the fact that the enhanced ion strength increased the hydrophobic interaction between Trp residues and the cavity of 1. The ,-helical conformation of 2 within the dimeric capsule of 1 was elucidated from detailed NOESY analysis. [source] | ||||||||||