Studies on some experimental parameters of radiometric flow injection analysis (RFIA) using137Cs and60Co

A simple radiometric flow injection analyzer with NaI(Tl) detector was used for the study of some experimental parameters of¹³⁷Cs and⁶⁰Co determination. A sample transfer system was developed employing both merging zone and sample injection principle.     

Thermal decomposition of 2,3,5-triphenyl tetrazolium halochromate complexes

Thermal decomposition studies of 2,3,5-triphenyl tetrazolium halochromates have been carried out upto 1000°C at a linear heating rate of 10 deg·min^?1. The complexes undergo two stage decomposition. First one corresponds to the redox decomposition of the complex along with the loss of a phenyl halide molecule and 3/2 mol of oxygen. While, the second step corresponds to the oxidation of the formazan type structure formed in the first step. The first step decomposition follows diffusion controlled reaction mechanism in a sphere governed by the equationg(α)=[1?(1?α)^1/3]². Activation energy and pre-exponential factors have been determined by Coats-Redfern model and Dixit-Ray model. Activation energy decreases as the electronegativity of the halide ion decreases.     

Levels of natural and artifical radioactivity in sediments in the Eastern Black Sea of Turkey

Sediment samples collected from the Eastern Black Sea in 1993 from 15 sampling stations of different depths have been analyzed. Natural and artifical radionuclide activity levels in offshore sediment samples from the Eastern Black Sea in Turkey are reported about seven years after the Chernobyl accident. The purpose of this paper is to follow up the earlier study and present results for the distributions of radionuclides in sediments of the Black Sea.     

Estimation of chromium in ores and beneficiated products: an ultrasonic approach

Cr(III) slowly forms a violet complex with EDTA at pH 3.5 +/- 0.2 under normal conditions. The complex formation can be catalyzed by irradiating the reacting mixture with ultrasonic waves. Quantitative formation of the complex was possible with ultrasonic waves of 15 W/cm(2) intensity within 7.5 min of sonication. This method may be successfully applied to the determination of chromium in ores and beneficiated products containing 20-60% Cr(2)O(3) without separating the analyte from the matrix elements.     

Quantitative analysis of sea-bed sediments from Eastern Black Sea by EDXRF spectrometry

Sea-bed sediments from Eastern Black Sea have been analyzed for their Fe, Ba and Sr contents using the methods of standard addition and energy dispersive X-ray fluorescence (EDXRF). Samples were prepared from powder sifted by a 200 mesh sieve. An annular 100 mCi²⁴¹Am radioactive source emitting 59.543 keV photons was used for excitation and a Ge(Li) detector, which has a 190 eV FWHM for 5.9 keV photons was used for intensity measurements. 2048 channels of the MCA are employed for 20 or 30 min. Dried and ground sea-bed sediments are found to contain 2.95–7.50% Fe, 0.032–0.268% Ba and about 73–273 ppm Sr. These results agree with those obtained via atomic absorption methods.     

Radiochemical studies on the separation of cobalt with sodium alginate

⁶⁰Co was used as indicator for studies on the separation of cobalt with sodium alginate. Effect of eight experimental parameters (digestion time, digestion temperature, mode of separation, concentration of reagents, pH, order of heating, ammonia, mixing of reagents) on the precipitation and separation of cobalt alginate have been investigated.     

A new synthesis of methanoisoindoles

Russian Journal of Organic Chemistry -     

A further test of the shape and anisotropy of the F---H2 interaction potential

A recently proposed anisotropic potential model for the interaction of a fluorine atom with a hydrogen molecule treated as a rigid rotor analysed by carrying out exact quantum calculations of elastic and rotationally inelastic differential cross sections for comparison with previoully reported F---H₂ and newly measured F---D₂ state selected measurements. The sensitivity of the cross sections to changes of the potential anisotropy and to isotopic substitution is examined. The results provide specific indications on the features of the best potential energy surface in terms of its average ‘size’ and its most likely anisotropy responsible for inelastic rotational excitations occuring at collision energies of about 85 meV.     

Hydrolysis of Native and Heat-Treated Starches at Sub-Gelatinization Temperature Using Granular Starch Hydrolyzing Enzyme

The effect of heat treatment below the gelatinization temperature on the susceptibility of corn, mung bean, sago, and potato starches towards granular starch hydrolysis (35°C) was investigated. Starches were hydrolyzed in granular state and after heat treatment (50°C for 30 min) by using granular starch hydrolyzing enzyme for 24 h. Hydrolyzed heat-treated starches showed a significant increase in the percentage of dextrose equivalent compared to native starches, respectively, with corn 53% to 56%, mung bean 36% to 47%, sago 15% to 26%, and potato 12% to 15%. Scanning electron microscopy micrographs showed the presence of more porous granules and surface erosion in heat-treated starch compared to native starch. X-ray analysis showed no changes but with sharper peaks for all the starches, suggested that hydrolysis occurred on the amorphous region. The amylose content and swelling power of heat-treated starches was markedly altered after hydrolysis. Evidently, this enzyme was able to hydrolyze granular starches and heat treatment before hydrolysis significantly increased the degree of hydrolysis.     

Combination of developed in-house method and application of Eichrom Sr resin to determine the radioactivity of <Superscript>90</Superscript>Sr in environmental sample

A method is described for the determination of ⁹⁰Sr in environmental samples using combination of developed in-house method, Eichrom Sr resin and Beta Counter. Strontium was efficiently, rapidly and simply separated from Ca and other interfering matrix components by Eichrom Sr resin. All the results in general showed good accuracy, high precision, reliable and in good agreement between these two measured and certified value of SRM (i.e. IAEA-375, IAEA-326, IAEA-152 and IAEA-414). As a whole, the procedure described in this work notably improves conventional methods in particular concerning the time needed, sample volume, safer and others. Thus, the introduced method was successfully performed and will be applied to actual sample for the determination of ⁹⁰Sr in different environmental materials such as soil, sediments, milk, biological sample, water etc.