RAFT polymerization of 4-vinylphenylboronic acid as the basis for micellar sugar sensors

Well-defined homo and mPEGylated block (co)polymers of the commercially available unprotected 4-vinylphenylboronic acid (4-VBA) monomer are reported based on reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymerization kinetics are studied in detail for homo and block (co)polymerizations with different chain transfer agents (CTAs) to optimize the preparation of well-defined polymer structures, eventually leading to comparatively low dispersities (Đ ≤ 1.25). Subsequently, block (co)polymers with methoxy poly(ethylene glycol) mPEG-b-P(4-VBA) are prepared using a mPEG-functionalized CTA. The formed block copolymer mPEG114 -b-P(4-VBA)30 is demonstrated to be pH and glucose responsive as its micellization behavior is dictated by pH as well as the presence of glucose. The glucose-responsive pH window of mPEG114 -b-P(4-VBA)30 is found to be pH 9-10 based on the DLS and TEM measurement.

A pilot survey on hand washing among some communities of West Bengal

A cross-sectional observational study was carried out between April to May 2006 by interview method and observation technique with the objective to know the knowledge regarding hand washing in the community and it was done in the slum and nonslum urban areas and also one rural area. The result shows that in urban slum area 98% washed their hands with soap after defecation; Only 36%, 16% and 2% washed their hands with soap before meal, before serving food and before cooking respectively. However, it was observed that 69% used soap and water for hand washing after cleaning the child's faeces. In rural area 71% used soap and water after defecation while 26% used mud or ash. Only 13%, 1%, 1% and 5% used soap and water before meal, before serving food, before cooking and after cleaning the child's faeces. 82.35% of respondents in non slum area and 89% of respondents in rural area considered that diarrhoea and dysentery could be prevented by hand washing while they did not give importance to hand washing in prevention of diarrhoea over other methods like cleanliness, boiling and purification of water. ARI was much higher (25.72%) in rural area followed by slum area (13.77%) and non-slum area (3.87%). Out of 30 observations among 302 interview made on hand-washing only first step i.e. palm washing (transient rubbing the palm with soap) was followed by all the participants observed. Time taken for such hand-washing was only around five seconds (ideal 15-30 seconds) in urban slum and rural areas while in non slum area it varied between 7-10 seconds on an average. No one followed any other steps of hand-washing, recommended by IFH.

Ligand-sensitized fluorescence of Tb3+ in Tb3+-dibutylphosphate complexes: application for the estimation of DBP

The fluorescence of Tb(3+) is sensitized by complexation with dibutylphosphate (DBP) and tri-n-butylphosphate (TBP). The excitation maximum for the Tb(3+)-DBP complex occurs at 218.5 nm, while that for the Tb(3+)-TBP complex is observed at 228.0 nm. Both complexes yield Tb(3+) fluorescence at 548 nm. The difference in the excitation maxima for the two complexes has been used to advantage for the estimation of DBP in the presence of TBP. DBP is the main degradation product of TBP in the PUREX process and the method described in this work can thus serve as a useful analytical tool in monitoring the quality of the TBP in the process. This method has been shown to be applicable for the estimation of DBP when present to an extent of 0.1-10% of TBP, in TBP/dodecane solutions.

Immunoreactive antigens of the outer membrane protein of Aeromonas hydrophila, isolated from goldfish, Carassius auratus (Linn.)

Aeromonas hydrophila causes disease under stress conditions or in concert with infection by other pathogens in goldfish. Sero-diagnostic and/or immunoprophylactic tools against Aeromonas infection in goldfish are not available so far. The present study was undertaken to fractionate and characterise the outer membrane proteins (OMP) of A. hydrophila and to identify suitable immunoreactive components. A total of 10 fractions were generated from crude OMP antigens upon gel permeation and subsequent ion-exchange chromatography. One of the fractionated antigens (GPID2), primarily a 57-kDa polypeptide, showed maximum sero-reactivity, even higher than the crude OMP. Suitability of GPID2 antigen for use in diagnostic preparations was assessed by dip-stick ELISA. In vitro goldfish lymphoproliferative ability of fractionated antigen, GPIID2 (primarily a 23-kDa polypeptide) was observed to be higher than all the fractionated antigens as well as crude OMP. It can be concluded that the 57 kDa and 23 kDa polypeptides of the OMP of A. hydrophila, possessing high immunoreactivity, should be given due attention while preparing immunodiagnostic and immunoprophylatic tools against Aeromonas infections in goldfish.

Effect of ligand structure on synergism in Tb3+-aromatic acid complexes: fluorescence lifetime studies

The fluorescence of Tb3+ sensitized by aromatic carboxylic acid ligands (benzoic, monomethylphthalic, monomethylterephthalic, trimesic, terephthalic, isophthalic, phthalic and mellitic acids) and the synergism displayed by these complexes when treated with TOPO/Triton X-100 have been studied by measuring lifetimes of Tb3+ emission. The lifetime of Tb3+ fluorescence was not significantly altered following complex formation with aromatic carboxylic acids, even though a significant enhancement in the Tb3+ fluorescence intensity was observed in every single case. However, when these Tb3+-aromatic acid complexes were treated with TOPO/Triton X-100, the lifetimes of the Tb3+ fluorescence increased markedly, but only with certain acids. Interestingly, even amongst the acids that showed an increase in lifetime with TOPO/Triton X-100, the lifetimes as a function of the pH of the solution was strongly dependent on the structure of the ligand. These differences and the reasons for such behavior are discussed, which shed light on the role of the structure of the ligand on the synergism process.

Correction for quenching in fluorimetric determinations using steady state fluorescence

Quenching corrections in fluorimetric estimations are arrived at using time resolved fluorometry, where the reduction in the lifetimes of the fluorophore in the presence of quenchers is a measure of the correction. A novel procedure for the correction of quenching in fluorimetric determinations using steady state fluorescence spectroscopy is described here. The method is based on the variation in the slope of the fluorescence versus concentration plots, as the quencher concentration is changed. As a test case, the procedure for the determination of uranium has been demonstrated in the presence of a number of metal ion quenchers.