Dielectric relaxation behavior of C5+ (70 MeV) swift heavy ion irradiated polyetheretherketone (PEEK) using TSDC technique

The dielectric relaxation characteristics of polyetheretherketone (PEEK) irradiated with C⁵⁺ (70 MeV) ion, have been investigated in the temperature range 60–230° as a function of poling temperature T _P (50, 100, 150, and 200°C), poling field E _P (200, 300, 400, and 500 kV/cm), and storage time t _s (2, 24, 48, and 120 h), using thermally stimulated discharge current (TSDC) technique. The TSDC spectra show a prominent maximum around glass transition temperature (T _g ～ 143°C) named as α-peak. This peak is attributed to the movement of ketone dipoles linked with the main chain. It is observed that the magnitude of α-peak increases with the increase in poling temperature and poling field. The peak current and area under the α-peak are found to be diminished with the increase of storage time t _s for electrets. The β-peak (space charge peak) is absent in irradiated PEEK samples as compared to pristine PEEK samples. The results obtained, in the present studies, are compared with the results on pristine samples. The activation energies and pre-exponential factor for PEEK samples determined using Bucci plot method.     

Studies on matrix interferences during uranium analysis by extractive liquid scintillation technique

Journal of Radioanalytical and Nuclear Chemistry - The efficiency of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) in reducing the influence of salinity and...     

Development of rapid solvent extraction based radioanalytical technique for estimation of 90Sr in the presence of natural and anthropogenic radionuclides

A radiochemical technique for estimation of ⁹⁰Sr concentration by direct extraction of ⁹⁰Y with bis (2-ethylhexyl) phosphate (HDEHP) in toluene was developed and standardized. About 90% ⁹⁰Sr retained in the aqueous phase at the optimized pH 4–4.5. Cerenkov counting with 0.04 g mL⁻¹ sodium salicylate as a wavelength shifter resulted in 7.5 fold increase its Cerenkov counting efficiency. The method was validated by estimating ⁹⁰Sr in certified reference materials like, IAEA TEL 2016-03 drinking water, Spruce needle and IAEA-156 Clover. The interference of naturally occurring Ra and its β progeny especially Pb was eliminated by means of Cerenkov counting. Conventional radiochemical separation was used to compare ⁹⁰Sr activity in effluent samples.

     

Monoclinic zirconia nanoparticle-catalyzed regioselective synthesis of some novel substituted spirooxindoles through one-pot multicomponent reaction in a ball mill: A step toward green and sustainable chemistry

A highly efficient, green as well as atom economical protocol for the synthesis of substituted spirooxindoles from m-ZrO₂ NPs catalyzed multicomponent reaction of isatin derivatives with ethyl cyanoacetate and 1,3-dicarbonyl compounds in a ball mill has been established. Because of the simple and readily available starting materials, easy operation, and high bioactivity of substituted spirooxindoles, this strategy can be broadly applied to medicinal chemistry. The recyclability of the m-ZrO₂ Nps catalyst is another emphasis of proposed methodology.     

Bifunctional fluorescent thiacalix[4]arene based chemosensor for Cu and F ions

A new thiacalix[4]arene based fluorescent sensor bearing two dansyl groups has been synthesized in cone conformation. In CH₃CN:CH₂Cl₂ (1:1), the presence of Cu (II) induces the formation of a 1:1 metal:ligand complex, which exhibits increasing emission at 433 nm at the expense of the fluorescent emission of 1 centered at 504 nm. The detection limit of the sensor for Cu²⁺ is 2×10⁻⁷ mol L⁻¹. For anion sensing, 1 shows a high selectivity for fluoride ions over other anions tested.     

An efficient method for the synthesis of methyl 11α-amino-3α,7α-diacetoxy-12-oxo-5β-cholan-24-oate

The synthesis of methyl 11α-azido-3α,7α-diacetoxy-12-oxo-5β-cholan-24-oate, methyl 11β-azido-3α,7α-diacetoxy-12-oxo-5β-cholan-24-oate and methyl 11α-amino-3α,7α-diacetoxy-12-oxo-5β-cholan-24-oate have been achieved. Mechanistic aspects for the decomposition of steroidal azidoketones to its enamines are discussed.     

Synthesis and binding studies of novel bisthiacalix[4]arenes with diimime linkages

A series of novel bisthiacalix[4]arenes with diimine linkages of different aromatic or heteroaromatic dialdehydes have been synthesized. The structure of one of the bisthiacalixarene has been analyzed by X-ray crystallography. These molecules quantitatively extract silver ion from aqueous into organic phase under neutral conditions.     

Fluoride-induced cyclization of pentacenequinone to higher quinones

Novel pentacenequinone derivatives 3, 7, and 10 have been synthesized via Suzuki-Miyaura coupling. Derivatives 3 and 7 having OTBS groups undergo irreversible fluoride-induced cyclization to substituted higher quinones in the presence of TBAF in dry THF using one-pot, two-step strategies in moderate yields. These functionalized higher quinone derivatives are freely soluble in THF and DMSO and can be used as precursors for the synthesis of higher acene derivatives.