The selective determination of halogens and sulphur in solution by atmospheric-pressure helium microwave-induced plasma emission spectrometry coupled to an electrothermal introduction system

Instrumentation is described for the direct determination of Cl, Br, I and S in dissolved samples. A tantalum furnace is coupled directly to a TM₀₁₀ cavity, in which a helium microwave plasma is generated at atmospheric pressure. Samples (20 μl) are dried, ashed and atomized; the free atoms are transported by helium to the cavity, where they are excited. Detection limits are in the sub-mg l^-1 region. The effect of counter cations is removed by the addition of 50 mg l^-1 potassium hydroxide, which also helps to suppress interferences by large amounts of matrix constituents, but the standard addition technique remains necessary to permit determinations that are reliable to within 5%.     

An inductively coupled plasma using 1 lmin of argon

The development and preliminary evaluation of an ICAP consuming only 1 $\text{l}\text{min}$ of argon is described. External cooling of the torch with pressurized air and a two tube plasma torch arrangement are essential. Detection limits and matrix effects are comparable to those of a conventional ICAP.     

МЕТОД ОБРАБОТКИ ДВУХ МЕРНЫХ СПЕКТРОВ СОВП АДЕНИЙ И ЕГО ПРИМЕНЕНИЕ К АНА ЛИЗУ γ-γ-СОВПАДЕНИЙ НА Ge(Li)-ДЕТЕКТОРАХ ПРИ РА СПАДЕ155Tb

The method of data processing of two-dimensional coincidence spectra is described and its application for the --coincidence spectra analysis in¹⁵⁵Tb is shown. The existence of levels with energies 86·5; 105·3; 118·0; 235·2; 266·6; 268·6; 286·8; 326·0; 367·7; 427· 4; 451·3; 488·8 keV in¹⁵⁵Gd nucleus is proved on the basis of --coincidences measured in¹⁵⁵Tb decay with Ge(Li)-detectors. Two new transitions with energies of 192 and 163 keV were found.     

Theory of Zeeman atomic absorption spectrometry

A theoretical analysis is presented of the signals observed with different systems that employ the Zeeman effect for background correction in analytical atomic absorption spectrometry.Magnetic modulation of the primary source of radiation offers basically the same possibilities as the deuterium background correction system. Correction for wavelength dependent background absorption is possible only when the magnetic field is applied to the absorbing vapour. Similar expressions are obtained for constant or variable magnetic fields directed either perpendicular or parallel to the optical axis. However, mere magnetic modulation of either the source or the atomizer cannot correct for non-absorbed lines.It is demonstrated that simultaneous correction for non-absorbed lines and background absorption can be attained with a variable magnetic field applied to the atomizer, by taking measurements at three discrete, different field strengths.     

155Gd levels excited in the decay of155Tb

Conversion electron spectra, gamma rays, and e- and - coincidences in the decay of¹⁵⁵Tb were investigated. The conversion electron spectra were measured with a toroidal six-gap beta spectrometer and a two-fold double-focusing 2 beta spectrometer. The gamma rays were measured by means of Ge(Li) detectors. The e--coincidence spectra were investigated by means of the six-gap beta spectrometer and a NaI(Tl)-gamma spectrometer. The --coincidences were studied by the method of two-dimensional analysis with the use of two coaxial Ge(Li) detectors.A number of transitions was found in¹⁵⁵Tb decay which were not observed up to now. A more complete scheme of the decay¹⁵⁵Tb ¹⁵⁵Gd is proposed.Conclusions were reached on the multipolarity of most transitions and possible spin and parity values were determined for the¹⁵⁵Gd levels.The populations of the excited levels in¹⁵⁵Gd ware determined and the lgft values were calculated.A comparison of the results obtained with the calculations by Solovev et al. based on the superfluid model of the nucleus enables one to assign the structure to the 592·6 keV state as follows: [521]–0·7%, [521]+Q ₁(20)–99% and to interpret the 559·9 keV level as a mixed state of the type [521]–42%, [521]+Q ₁(22)–37%, [523]+Q ₁(22)–16%.In conclusion the author express their gratitude to T. Galanova, T. Parneanova and L. erná for help in handling the experimental data.     

Experimental estimation of fluorescence power efficiencies of several atoms in three turbulent flames used in atomic fluorescence flame spectrometry

An experimental system for the measurement of approximate atomic fluorescence power efficiencies of atoms in turbulent flames used in atomic fluorescence flame spectrometry is described. An expression is derived for the power efficiency as a function of instrumental parameters. Experimentally measured power efficiencies for eleven elements in fuel-rich oxyhydrogen, fuel-rich oxyacetylene, and fuel-rich hydrogen/argon/entrained air flames are given. The power efficiencies vary considerably from one spectral line to another, but as a result of the entrainment of ambient air into the turbulent flames, the values obtained in different flames are approximately equal. It is also shown that fluorescence radiation should rarely produce a significant error in atomic absorption spectrometry.     

Structure of 72,74Se at high spin

Lifetimes of high spin states up to { }=22⁺ in the yrast positive parity bands have been measured to investigate the shape evolution with increasing spin in ^{72, 74}Se. The Q _t values derived from these measurements indicate that prolate shape stabilizes for ⁷²Se, while a triaxial shape develops for ⁷⁴Se at higher spins. Comparison of the observed trend in Q _t with spin for ^{72, 74}Se with that of the corresponding kryptones isotones emphasizes the stability provided by N=38 prolate shell gap even at high rotational frequency.     

The design and synthesis of a selective inhibitor of fucosyltransferase VI

Inversion of configuration of the C-2[prime or minute] hydroxyl of methyl N-acetyllactosamine was accomplished by a two-step procedure involving oxidation to a ketone followed by reduction with NaBH(4). After deprotection, the resulting derivative was examined as a substrate for [small alpha]-(2,6)- and [small alpha]-(2,3)-sialyltransferase and fucosyltransferase III, IV, V and VI. It was found that none of these enzymes could glycosylate. However, it showed exquisite selectivity for inhibition of fucosyltransferase VI. The kinetic data support an unusual mechanism in which the inhibitor can bind to the GDP-fucose complex as well as another enzyme form.     

Calcium carbonate decomposition

Calcium carbonate decomposes under well-defined conditions giving CaO (solid) and CO₂ (gas). The process kinetics are known to be strongly influenced by the CO₂ partial pressure and temperature. In dynamic conditions, as in thermogravimetric analysis (TG) and differential thermal analysis (DTA), kinetics influence the observed heat effect and mass losses, as was shown in semi-static studies by Hyatt et al. (J Am Ceram Soc 41:70–74, 1). However, differing DTA and TG curve shapes are reported in the literature even under supposedly comparable conditions. The differences are attributed in part to the design of the equipment and in part to differing crystalline states of the precursor calcium carbonate. To resolve these uncertainties, the TG has been performed at different heating rates and at different but controlled partial pressures of CO₂. The results are reported and critically evaluated in the light of the data obtained, and the kinetic parameters as reported by Hyatt et al. (J Am Ceram Soc 41:70–74, 1) are re-evaluated.