Polymeric Titanium Oxychloride Sorbent for 188W/188Re Nuclide Pair Separation

Abstract

The chemical synthesis conditions (TiCl₄: iPrOH reagent ratio and reaction temperature scheme) were optimized for the preparation of polymeric titanium oxychloride sorbent which met the requirements for clinically useful ¹⁸⁸W/¹⁸⁸Re generator production, such as high W-adsorption capacity, high ¹⁸⁸Re-elution yield, low ¹⁸⁸W-breakthrough, and good mechanical stability. This polymeric material was formed by polycondensation of titanium-oxychloride units, the chemical formula of which was supposed as [OTiO (Ti₄₀ Cl₈₀ (OH) ₈₀ (TiO₂)₉₅.60H₂O) OTiO]_n. The effect of the W-content of tungstate solution on the WO₄ ^2? ion adsorption (with minimizing the poly-tungstate ion adsorption) and its covalent bonding with the Ti metal atoms in the polymeric matrix were justified with respect to the optimal W-adsorption conditions for the preparation of a useful ¹⁸⁸W/¹⁸⁸Re generator column. The high W-adsorption capacity of about 515.6 mg W/g sorbent and ¹⁸⁸Re elution yield of higher than 85% wereachieved. The large difference in the distribution ratio values found for alumina and polymeric titanium oxychloride sorbent in 0.005% NaCl solution (D_{W, Re-188} = 50 and D_{W, Re-188} = 1.0, respectively) offered an advantage for the preparation of a consecutive-elution based ¹⁸⁸Re generator system which combined both ¹⁸⁸Re elution and ¹⁸⁸Re concentrating processes in one portable system. This generator system is of a tandem column type which consists of a polymeric titanium oxychloride sorbent coupled to an alumina column. This system gave a ¹⁸⁸Re concentration factor of approximately 10. The overall ¹⁸⁸Re yield achieved from this system was >80%. ¹⁸⁸W isotope and elemental tungsten breakthrough were not detected in its ¹⁸⁸Re eluate. This system thus offers a potential application for clinically useful ¹⁸⁸Re production using low specific radioactivity ¹⁸⁸W (around 500 mCi/g) producible in a medium neutron flux reactor.     

Critical Analysis of Fibre‐Reinforced Polymer Near‐Surface Mounted Double‐shear Pull‐out Tests

The study of the bond behaviour between fibre‐reinforced polymer (FRP) systems and concrete is an issue that nowadays attracts many researchers. The scientific community dedicated to the research of FRP reinforcement has been conducting numerous experimental programmes aiming to assess the local bond–slip law of the FRP–adhesive–concrete connection. This paper reports the relevant results obtained by the Structural Composite Research Group of Minho University in the scope of an international Round Robin Test. The suitability of the recommended test setup to derive a local bond constitutive law for modelling the bond behaviour of near‐surface mounted reinforcement systems is discussed based on a deep interpretation of the results.     

High porosity,responsive hydrogel copolymers from emulsion templating

Hydrogels, three‐dimensional hydrophilic polymer network structures, can absorb many times their dry weight in water. PolyHIPEs are highly porous polymers synthesized within high internal phase emulsions (HIPEs). Here, the water uptakes in novel hydrogel polyHIPE copolymers of hydroxyethyl methacrylate (HEMA, a non‐ionic monomer) and methacrylic acid (MAA, an ionic monomer) were investigated. The PHEMA‐based polyHIPE had a density of 0.14 g cm^?3, void diameters of 50–100 µm and a void‐dominated Fickian water uptake of around 10.4 g g^?1. The polyHIPE density increased, and the porous structure became less polyHIPE‐like, with increasing MAA content, reflecting a reduction in the stability of the HIPE. The water uptake increased with increasing pH for all the copolymers and the water absorption mechanism changed from Fickian at pH 2 to anomalous, dominantly case II, at pH 10. The maximum uptake of 18.2 g g^?1 at pH 10, for a HEMA to MAA mass ratio of 1/1, was ascribed to hydrogel‐swelling‐driven void expansion. The hydrogel's absorptive and responsive properties were amplified by the polyHIPE's porous structure. These results demonstrate that the compositions of hydrogel polyHIPE copolymers can be designed to enhance their water uptake. © 2015 Society of Chemical Industry     

Molecularly imprinted polymer nanomaterials and nanocomposites by controlled/living radical polymerization

Since the pioneering work of Wulff and Mosbach more than 30 years ago, molecular imprinting of synthetic polymers has emerged as a robust and convenient way for synthesizing polymeric receptor materials bearing specific recognition sites for target molecules. The resulting materials, molecularly imprinted polymers (MIPs), are therefore commonly referred to as ‘plastic antibodies’. They are obtained by polymerizing a scaffold around a target, or a derivate thereof, which acts as a molecular template. MIPs have been successfully applied in many areas including affinity separation, immunoassays, chemical sensing, solid-phase extraction, drug delivery, cell and tissue imaging, direct synthesis and catalysis. In terms of affinity and selectivity, MIPs are on a par with biological receptors like antibodies, and this is accompanied by a superior chemical and physical stability, compatibility with organic media, reusability, easy engineering and low cost. These advantages represent the main reasons for the wide interest raised around molecularly imprinted materials. Mainly produced by free radical polymerization (FRP) of vinyl monomers, MIPs have also taken advantage of the introduction of controlled/living radical polymerization (CRP) techniques, which have literally transformed polymer chemistry over the last decade. This review describes the advantages arising from the use of CRP in synthesizing MIPs, both in terms of sheer binding properties as well as for their remarkable potential for post-polymerization functionalization, for the synthesis of MIP nanomaterials and for the integration of MIPs into composites and hybrid materials. The benefits of using CRP are critically assessed with respect to the still largely applied FRP and guidelines are provided for choosing the most convenient technique to fit a specific targeted application of MIPs.     

Corrosion-free electrochemical synthesis of polyaniline using Cu counter electrode in acidic medium

Polyaniline (PAni) was electrochemically synthesized from aniline sulfate (AS) in the presence and in absence of H₂SO₄ using Cu counter electrode. No significant corrosion of the Cu electrode was found while synthesizing from AS in presence of H₂SO₄, whereas relatively higher corrosion of Cu as well as contamination of synthesized PAni with corroded Cu were observed for the synthesis from aniline in presence of H₂SO₄ or from AS in the absence of H₂SO₄. Corrosion-free synthesis yields PAni free from contamination of Cu and exhibits smaller particle size and superior electrical and supercapacitive behavior compared to the process exhibiting corrosion of counter electrode.     

Detection of a Specific Biomarker for Epstein-Barr Virus Using a Polymer-Based Genosensor

This paper describes methodology for direct and indirect detections of a specific oligonucleotide for Epstein-Barr virus (EBV) using electrochemical techniques. The sequence of oligonucleotide probe (EBV1) revealed a high sequence identity (100%) with the EBV genome. For the development of the genosensor, EBV1 was grafted to the platform sensitized with poly(4-aminothiophenol). After that, the hybridization reaction was carried out with the complementary target (EBV2) on the modified electrode surface using ethidium bromide as DNA intercalator. The oxidation peak currents of ethidium bromide increased linearly with the values of the concentration of the complementary sequences in the range from 3.78 to 756 μmol·L⁻¹. In nonstringent experimental conditions, this genosensor can detect 17.32 nmol·L⁻¹ (three independent experiments) of oligonucleotide target, discriminating between complementary and non-complementary oligonucleotides, as well as differentiating one-base mismatch, as required for detection of genetic diseases caused by point mutations. The biosensor also displayed high specificity to the EBV target with elimination of interference from mix (alanine, glucose, uric acid, ascorbic acid, bovine serum albumin (BSA), glutamate and glycine) and good stability (120 days). In addition, it was possible to observe differences between hybridized and non-hybridized surfaces through atomic force microscopy.