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A monomer 7-hydroxy-4-methyl-8-(4′-allyloxypiperazin-1′-yl) methylcoumarin with blue fluorescence was synthesized. The present investigation dealt with the synthesis and characterization of a coumarin monomer, containing a piperazine group. Then it was copolymerized with N-vinylpyrrolidone to obtain a water-soluble fluorescent copolymer (poly(Al-HMPC-co-VP)). The fluorescence characteristics of the polymer as a function of pH sensor were investigated in aqueous solution. It was found that the polymer displayed sensitive fluorescence signal amplification over a wide pH scale, which was ascribed to a photoinduced electron transfer from the piperazine receptor to the coumarin fluorophore. In addition, the influence of metal cations on the fluorescence intensity of poly(Al-HMPC-co-VP) were also studied. Obvious fluorescence enhancement was due to the photophysical response of the polymer to the presence of Ni ion. The results suggest that copolymer may offer potential application as a reusable polymer for sensor protons and Ni ion in aqueous solution. [ABSTRACT FROM AUTHOR]

Abstract: The coexistence curves of {water+KCl+sodium di(2-ethyl-1-hexyl)sulphosuccinate (AOT)+decane} microemulsion system have been determined by measuring refractive index at constant pressure in the critical region. The critical exponent β has been deduced from coexistence curves. The values of β decrease with increase in the temperature range (T−Tc) and approach the Ising value in the region of 1 K above Tc. The experimental results have been analyzed to examine the Wegner correction terms and the behaviors of the diameters of the coexistence curves. It was found that addition of salt KCl into the ternary microemulsion of {water+AOT+decane} almost did not change the critical concentration but significantly raised the critical temperature. Addition of salt also significantly reduced the region of validity of simple scaling and the efficiency of the variable of volume fraction ϕ as an order parameter to describe the critical asymptotic behaviors. [Copyright &y& Elsevier]

By the complete discrimination system for the polynomial, we give the classification of single travelling wave solutions to the Camassa-Holm-Degasperis-Procesi equation for some values of the convective parameter. [ABSTRACT FROM AUTHOR]

Abstract: Adaptation of cyclic brush polymer for drug delivery applications remains largely unexplored. Herein, cyclic brush copolymer of poly(2‐hydroxyethyl methacrylate‐g‐poly(N‐isopropylacrylamide‐st‐N‐hydroxyethylacrylamide)) (cb‐P(HEMA‐g‐P(NIPAAm‐st‐HEAAm))), comprising a cyclic core of PHEMA and thermosensitive brushes of statistical copolymer of P(NIPAAm‐st‐HEAAm), is designed and synthesized successfully via a graft‐from approach using atom transfer free radical polymerization from a cyclic multimacroinitiator. The composition of the brush is optimized to endow the resulting cyclic brush copolymer with a lower critical solution temperature (LCST) slightly above the physiological temperature, but lower than the localized temperature of tumor tissue, which is suitable for the hyperthermia‐triggered anticancer drug delivery. Critical aggregation concentration determination reveals better stability for the unimolecular nanoparticle formed by the cyclic brush copolymer than that formed by the bottlebrush analogue. The dramatically increased size with elevated temperatures from below to above the LCST confirms hyperthermia‐induced aggregation for both formulations. Such structural destabilization promotes significantly the drug release at 40 °C. Most importantly, the drug‐loaded cyclic brush copolymer shows enhanced in vitro cytotoxicity against HeLa cells than the bottlebrush counterpart. The better stability and higher therapeutic efficacy demonstrates that the thermosensitive cyclic brush copolymer is a better formulation than bottle brush copolymer for controlled drug release applications. [ABSTRACT FROM AUTHOR]