Dosimetric investigations on radiation-induced Ag nanoparticles in a gel dosimeter

Journal of Radioanalytical and Nuclear Chemistry - Radiation-induced Ag° nanoparticles (NPs) in silver nitrate gel dosimeter incorporating various components was investigated in the dose range...     

Diversity through a branched reaction pathway: generation of multicyclic scaffolds and identification of antimigratory agents

A library of 91 heterocyclic compounds composed of 16 distinct scaffolds has been synthesized through a sequence of phosphine-catalyzed ring-forming reactions, Tebbe reactions, Diels-Alder reactions, and, in some cases, hydrolysis. This effort in diversity-oriented synthesis produced a collection of compounds that exhibited high levels of structural variation both in terms of stereochemistry and the range of scaffolds represented. A simple but powerful sequence of reactions thus led to a high-diversity library of relatively modest size with which to explore biologically relevant regions of chemical space. From this library, several molecules were identified that inhibit the migration and invasion of breast cancer cells and may serve as leads for the development of antimetastatic agents.     

Homo- and copolymerization of N-(2-thiazolyl)methacrylamide with different vinyl monomers: Synthesis,characterization, determination of monomer reactivity ratios and biological activity

N-(2-thiazolyl)methacrylamide (TMA) monomer was synthesized from 2-aminothiazole by two different methods. The homo- and copolymerization of this monomer with methyl methacrylate (MMA), styrene (St), acrylonitrile (AN), and vinyl acetate (VA) were performed in dimethyl formamide using 1 mol% AIBN at 70°C. The copolymerization behavior was studied in a wide composition interval with the mole fractions of TMA ranging from 0.1 to 0.7 in the feed. Characterization using FTIR and 1HNMR techniques confirmed the structure of the monomer and the prepared homo- and copolymers, but the copolymers compositions were determined from sulphur analysis. The monomer reactivity ratios were computed using Fineman and Ross and Kelen and Tüdös methods for the systems TMA-MMA, TMA-St, TMA-AN and TMA-VA and were found to be r ₁ = 0.59 ± 0.05, r ₂ = 2.72 ± 0.03; r ₁ = 0.39 ± 0.02, r ₂ = 0.90 ± 0.01; r ₁ = 0.77 ± 0.06, r ₂ = 1.99 ± 0.04 and r ₁ = 0.80 ± 0.08, r ₂ = 0.40 ± 0.05 respectively (r ₁ corresponds to monomer reactivity ratio of TMA). The Q and e values for TMA monomer were found to be 1.079 and ?0.054. The synthesized monomer and polymers were tested in vitro for biological activity against some microorganisms, using the disk diffusion technique. Generally, all the polymers were effective against the tested microorganisms, but their growth-inhibition effects varied.     

Photo-luminescence of Risø B3 and PVB films for application in radiation dosimetry

Risø B3 film dosimeters (23 μm) prepared from poly(vinyl butyral) (PVB) incorporating pararosaniline cyanide, as the radiation-sensitive element and PVB films (25 μm) prepared from PVB without any additives are investigated for γ-radiation measurement using spectrofluorimetry based on their emission properties. The unirradiated Risø B3 film when excited at 554 nm shows an emission band at 602 nm while PVB film shows an emission band at 305 nm when excited at 235 nm wavelength. The fluorescence intensity of both emission bands decreases with the increase of absorbed dose due to the damage caused by ionizing radiation. The useful dose range of Risø B3 film extends up to 120 kGy while that of PVB film extends up to 60 kGy. The response of Risø B3 film increases with the increase of relative humidity during irradiation while that of PVB has less effect in the humidity range of 20–70%. The percent uncertainty associated with the measurement of the dose response was found to be ±3% (1σ) for both films. Risø B3 and PVB films show good post-irradiation stability in dark and indirect daylight where the deviation in the response overall a 2-month storage period was found to be ±5% for Risø B3 and ±2% for PVB.     

A new spectrophotometric readout for the alanine-triphenyl tetrazolium chloride system for high-dose dosimetry

The electron spin resonance (ESR) readout of radical concentration in irradiated L-alanine is well known as a transfer dosimetry system, however, the high cost of the ESR equipment is a serious handicap for large-scale routine application. In this study the reaction between irradiated L-alanine powder and aqueous solution of triphenyl tetrazolium chloride (TTC) was studied. The radical produced by irradiation of alanine reacts during the dissolution with TTC forming pink-colored formazans with absorption maxima around 401 and 487 nm. This readout method can be used in the 2–200 kGy dose range.