Controlled partial neutralization of amphoteric ion exchange resin for improved metals separation

Controlled partial neutralization of an amphoteric aminomethylphosphonium functional ion exchange resin (Lewatit TP-260) was investigated. The particular goal of controlled neutralization was to replace H⁺ in the acidic phosphonium groups with Na⁺ ions but leave the basic amino groups protonated. In this manner, metals’ sorption is enhanced and undesired pH changes during the metal separation process are avoided. The conjugate bases of organic weak acids (sodium formiate, sodium acetate and sodium citrate), sodium phosphate and NaOH were studied as neutralizing agents. The organic acid salts and sodium phosphate were all found to be suitable. Lengthening the neutralization cycle and using more concentrated neutralization agents were found to yield higher extents of neutralization and more uniform profiles along a resin bed. Concentrated NaOH also neutralized the amine group from the resin. With dilute NaOH, desired extent of neutralization was not achieved within a reasonable time. The effect of partial neutralization on metal sorption was tested with dynamic single column experiments. 5.5 BV of Ag–NaCl solution could be purified from Ca, Mg, Pb and Zn when the resin was partially neutralized with 2.0 M NaAc. With the acid form resin, the impurity metals broke through at 1.0 BV.     

Slow release of a biocidal agent from polymeric microcapsules for preventing biodeterioration

Water-soluble biocides are prone to excessive leaching and high concentrations are therefore required in surface coatings for successful protection of a surface against biodeterioration. Encapsulation prolongs the lifetime of biocides in different matrices by protecting them from leaching and by releasing them slowly. In this study, sodium benzoate as a model water-soluble biocidal agent and Congo Red dye as an capsulation indicator were incorporated into branched polyethyleneimines (PEIs) with molecular weights of 1300 and 5000 g/mol. Microscopic investigations verified that the Congo Red dye and sodium benzoate were entrapped within the capsules. The encapsulation capacity, release behaviour and efficiency of the encapsulated model biocide against two brown rot species Coniophora puteana and Serpula lacrymans were determined. The encapsulated water-soluble model biocide inhibited the growth of the decay fungi. The release of the biocide was based on slow diffusion from the capsules. The molecular weight of the encapsulated agent and the polyethyleneimine affected the release rate.     

A Solder Alloy Filled Z-Axis Conductive Epoxy Adhesive

Epoxy adhesives filled with four different volume fractions of eutectic tin-bismuth solder alloy were prepared and the effect of filler content on the electrical and mechanical properties of these anisotropic electrically conductive adhesives was investigated. The results show that the adhesive containing the lowest amount of the filler alloy had the best combination of conductivity, insulation resistance and shear strength. The DSC-measurements suggested that the filler melts before the cure of the resin begins which allows the filler to wet and bond well to the conductors. This was verified by SEM/EPMA examinations. A temperature cycling test and high humidity, high temperature treatment were conducted on the best composite adhesive. The temperature variation had no effect on conductivity of the joints while humid and hot environment decreased the conductivity.     

Novel Dextran-Supported Biological Probes Decorated with Disaccharide Entities for Investigating the Carbohydrate–Protein Interactions of Gal-3

The quest for novel natural-like biomolecular probes that can be used to gain information on biological recognition events is of topical interest to several scientific areas. In particular, the recognition of carbohydrates by proteins modulates a number of important biological processes. These molecular recognition events are, however, difficult to study by the use of naturally occurring oligosaccharides and polysaccharides owing to their intrinsic structural heterogeneity and to the many technical difficulties encountered during the isolation of sufficient quantities of pure material for detailed structural and biological studies. Therefore, the construction of homogenous biomolecular probes that can mimic both the biophysical properties of polysaccharide backbones and the properties of bioactive oligosaccharide fragments are highly sought after. Herein, synthetic methodology for the construction of well-defined bioconjugates consisting of biologically relevant disaccharide fragments grafted onto a dextran backbone is presented, and a preliminary NMR spectroscopy study of their interactions with galectin-3 as a model lectin is conducted.