Application of gamma-ray spectrometry for the assay of uranium in crude UF4—An input material used for producing nuclear grade U-metal at the natural uranium conversion plants

A -spectrometric method has been developed for the assay of uranium in crude UF₄, which is used as a secondary source of input material for producing nuclear grade U-metal at natural uranium conversion plants. The method makes use of a NaI (Tl) detector coupled with a multichannel analyzer. The 1 MeV -ray of²³⁸U is used for calibration. A method for the fabrication of uniform -assay calibration standards is also suggested, based on the results of this investigation. The calibration standards were prepared by soaking the matrix in uranium solution and then drying the whole material. The amount of²³⁸U in the crude UF₄ sample was directly estimated by comparing the areas under the 1 MeV -ray peak of known calibration standards with the corresponding areas of the samples to be measured. 100 g each of the standard and the sample were counted. 5 crude UF₄ samples were analyzed by this method. The uranium contents in these samples were found to be in the range of 12.2–28.7 g. To compare the -ray spectrometry results with a completely independent method, chemical analysis by potentiometry of all the samples was also done. The -spectrometric results were found to agree within ±18% with the chemical analysis results.     

Correlation between the fluorescent response of microfluidity probes and the water content and viscosity of ionic liquid and water mixtures

Accurate data on transport properties such as viscosity are essential in plant and process design involving ionic liquids. In this study, we determined the absolute viscosity of the ionic liquid + water system at water mole fractions from 0 to 0.25 for three 1-alkyl-3-methylimidazolium ionic liquids: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide and 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide. In each case, the excimer to monomer ratio for 1,m-bis(1-pyrenyl)alkanes (m= 3 or 10) was found to increase linearly with the mole fraction of water. Of the probes studied only PRODAN and rhodamine 6G, both of which have the ability to participate in hydrogen bonding, exhibited Perrin hydrodynamic behavior in the lower viscosity bis(trifluoromethane sulfonyl)imides. As a result, these probes allow for the extrapolation of the absolute viscosity of the ionic liquid mixture from the experimental fluorescence steady-state polarization values.     

<Superscript>90</Superscript>Y-DOTA-Lanreotide: A potential agent for targeted therapy

Several human tumors such as neuroendocrine tumors, medullary thyroid carcinoma, etc., express somatostatin receptors which specifically bind somatostatin and its analogues such as lanreotide, octreotide, etc. In order to prepare a therapeutic agent for targeting such tumors, attempts were made to prepare ⁹⁰Y-DOTA-Lanreotide. Lanreotide could be successfully conjugated with the macrocyclic chelating agent DOTA (1,4,7,10-tetraaza cyclododecane tetracetic acid) which forms stable complexes with ⁹⁰Y. ⁹⁰Y-DOTA-Lanreotide could be prepared in >98% radiochemical purity and remained stable for 72 hours at room temperature. The tracer showed specific binding to A431 cells. Biodistribution studies in C57BL6 mice bearing melanoma showed ∼1.3% uptake pergram of tumor at 24-hour p.i.     

Synthesis and characterisation of copolymers containing geraniol and styrene initiated by benzoyl peroxide

Alternating copolymer(s) containing geraniol and styrene sequences have been synthesized by using benzoyl peroxide as initiator in xylene at 80 °C. The copolymerisation follows ideal kinetics. The formation of the copolymer is confirmed by the presence of peaks at 7-7.5δ due to the phenyl group and 7-7.7δ due to the alcoholic group and 2900 cm⁻¹ due to the phenyl groups in the FTIR spectrum of the copolymer. The values of r₁(Sty)=0.76 and r₂(Ger)=0.03, calculated by the Kelen-Tüdos method, indicates some alternating nature of the copolymer. The glass transition temperature (T_g) found by differential scanning calorimetry, is 90 °C. The Alfrey-price Q-e parameters for geraniol are 0.221 and 0.649.     

Thermodynamic properties of quinoxaline-1,4-dioxide derivatives: a combined experimental and computational study

The mean (N-O) bond dissociation enthalpies were derived for three 2-methyl-3-(R)-quinoxaline 1,4-dioxide (1) derivatives, with R = methyl (1a), ethoxycarbonyl (1b), and benzyl (1c). The standard molar enthalpies of formation in the gaseous state at T = 298.15 K for the three 1 derivatives were determined from the enthalpies of combustion of the crystalline solids and their enthalpies of sublimation. In parallel, accurate density functional theory-based calculations were carried out in order to estimate the gas-phase enthalpies of formation for the corresponding quinoxaline derivatives. Also, theoretical calculations were used to obtain the first and second N-O dissociation enthalpies. These dissociation enthalpies are in excellent agreement with the experimental results herewith reported.     

One-pot general synthesis of metalloporphyrins

A new general one-pot method for the synthesis of various metalloporphyrins has been developed from pyrrole and substituted aldehydes using transition metal salts. This method allows higher working concentrations than those previously reported. Along with the reported metalloporphyrins, some new metalloporphyrins were synthesized in good yield.     

Spectroscopic investigations in molecularly organized solvent media. Part 5. Fluorescence behavior of polycyclic aromatic hydrocarbons dissolved in cetylpyridinium chloride+zwitterionic and cetyltrimethylammonium chloride+zwitterionic mixed surfactant systems

Applicability of the cetylpyridinium (CPy(+)) cation as a selective fluorescence quenching agent for discriminating between alternant versus nonalternant polycyclic aromatic hydrocarbons (PAHs) is examined for 25 representative solutes dissolved in two aqueous micellar cetylpyridinium chloride (CPC)+zwitterionic surfactant solvent media. Experimental results show that the CPy(+) cation effectively quenched fluorescence emission of all 10 alternant PAHs studied despite the presence of strong intramicellar coulombic interactions. Emission intensities of the 15 nonalternant PAHs also decreased upon addition of CPC to the zwitterionic surfactant solutions. Reduction in emission intensities for the nonalternant PAHs is rationalized in terms of changes in micellar structure caused by the coulombic interactions, rather than from loss of quenching selectivity by the CPy(+) cation.     

Design and development of a common synthetic strategy for a variety of 1-N-iminosugars

[formula: see text] A new synthetic strategy has been developed for a general approach toward the synthesis of a variety of 1-N-iminosugar-type glycosidase inhibitors utilizing precursors developed by the PET-mediated cyclization of alpha-trimethylsilylmethylamine radical cation to a tethered pi-functionality.     

Generalized mean-square amplitudes of vibration in some XY4 type ions (II)

The generalized mean-square amplitudes of vibration and mean amplitudes of vibration have been computed for CrO^3-₄, Mn¹⁸O^-₄, MoSe^2-₄ and WSe^2-₄ ions at three temperatures, T = 0°K, T = 298°K, T = 500°K, employing Cyvin's method. The results have been discussed in the light of atomic weight and electronegativity of the atom in the ionic system.