Preparation of a protected triamino analogue of cholic acid and sequential incorporation of amino acids in solution and on a solid support

We have prepared a triamine derivative of cholic acid with protecting groups on the amines that allow sequential amide formation. The triamine was formed from 3 alpha,7 alpha, 12 alpha-trihydroxycholan-24-ol with good stereoselectivity. Sequential removal of the amine protecting groups and amide formation was achieved in high-yielding steps and was performed in solution and on a solid support.     

Gamma-ray tracking with the MARS detector

The feasibility of the entire process of -ray tracking is demonstrated experimentally for the first time. The accuracy of the results is tested by the capability for Doppler correction of -rays emitted in flight. The resolution of the 847.8 keV ( ) transition detected with the MARS detector after Coulomb excitation of a ⁵⁶Fe beam could be improved from 15 keV to below 5 keV (FWHM).Received: 28 October 2002, Published online: 2 March 2004PACS: 29.30.Kv X- and gamma-ray spectroscopy - 29.40.Gx Tracking and position-sensitive detectors - 29.40.Wk Solid-state detectorsC.A. Ur: On leave from: NIPNE, Bucharest, Romania.     

Gamma-ray feeding and decay of superdeformed states

We report on four recent results concerning the population and the decay of superdeformed states, namely the structure of excited superdeformed states in ¹⁹⁴Hg, the search for fine structure of the last superdeformed transitions in ¹⁹⁴Pb, the primary decay-out strength analysis in ¹⁹⁴Hg and, as a consequence of this, the possibility of using the decay-out as a tool to study order-to-chaos properties of normally deformed states.Received: 3 December 2002, Published online: 17 February 2004PACS: 21.10.Re Collective levels - 23.20.Lv transitions and level energies - 24.60.-k Statistical theory and fluctuations - 24.60.Lz Chaos in nuclear systems - 27.80. + w F. Hannachi: Present address: CENBG/IN2P3, Gradignan, France.H. Amro: Present address: WNSL, Yale, USA.K. Hauschild: Present address: CSNSM/IN2P3, Orsay, France.T. Kröll: Present address: TU, Munich, Germany.M. Rejmund: Present address: GANIL, Caen, France.     

Pseudo-spin band in the odd-odd nucleus 172Lu

High-spin states in the odd-odd nucleus ¹⁷²Lu have been populated in a ¹⁷⁰Er(⁷Li, 5n) reaction and the emitted -radiation was detected with the GASP array. Two sequences of a new identical band have been observed with the transition energies in the favoured and unfavoured sequences being identical within keV at low spins and keV at high spins over the whole observed spin range. Aninterpretation as a pseudo-spin singlet band of configuration is proposed. It represents the best example of a pseudo-spin singlet band in normal deformed nuclei known until now.Received: 19 February 2003, Revised: 27 March 2003, Published online: 12 August 2003PACS: 21.10.-k Properties of nuclei; nuclear energy levels - 21.10.Re Collective levels - 23.20.Lv transitions and level energies - 27.70.+q      

The physicochemical dynamics of disperse systems in the preparation of structured sorbents and catalysts

The formation of the structure of sorbents and catalysts on the basis of high-dispersity solid phases under dynamic conditions was considered. The rheokinetic changes in contact interactions and rheological properties of high-dispersity component compositions under the conditions of continuous shear combined with oscillations were analyzed in terms of the new direction in physical chemistry of disperse systems, physicochemical dynamics. The reasons for and conditions of attaining maximum system uniformity were substantiated.     

Speciation of mercury by continuous flow liquid-liquid extraction and inductively coupled plasma atomic emission spectrometry detection

An accurate, precise, sensitive and automated non-chromatographic method for methylmercury speciation based on a selective continuous liquid-liquid extraction of methylmercury, into xylene, as bromide and cold mercury vapour generation directly from the organic phase and final ICP-AES mercury detection is proposed. Both separation steps, liquid-liquid and gas-liquid are accomplished in a continuous mode and on line with ICP-AES as detector. The detection limit attained for methylmercury was 4ng·ml^–1 (as mercury). The precision of the determination at a concentration level around 20 times the detection limit was +-5%. The proposed methodology has been applied successfully to the speciation of methylmercury and inorganic mercury in spiked sea water and spiked urine samples.     

Study of the occupation site for the ancient iron smelters at Samaru-west, Nigeria, using neutron activation analysis

Summary Instrumental neutron activation analysis (INAA) has been employed to investigate the relationship between three ancient occupation sites — Samaru-west, Pantaki and Tsauni in Kaduna State, Nigeria, based on the analysis of cultural deposits at the sites. Samaru-west was found to be related with Pantaki site but not so with the Tsauni site. Elemental profiles for the pottery excavated from each site have been established.     

Molecular Complexes of Crown Ethers: Part 7. Effect of Surfactant on the Charge-Transfer Complex between Dibenzo-18-Crown-6 and Tetracyanoethylene

The charge transfer complexes (CTC) of dibenzo-18-crown-6 (DB 1 8C6) andtetracyanoethylene (TCNE) were studied in the presence of the surfactant TritonX-100. It was found that the stability of the CTC increases with increasingconcentration of the donor, acceptor and the surfactant. This suggests that thecharge transfer complex is encapsulated in the micelle structure. Results of theeffect of time on the complex stability are also presented.     

Thermoanalytical investigation of 1,2-diimidazoloethane complexes of copper,mercury and cadmium by TG-DTG-DTA techniques in static air atmosphere

The iodide complexes of transition metals with 1,2-diimidazoloethane (DIE) of the general formula MLI₂, (M=Cu(II), Hg(II), Cd(II); L=1,2-diimidazoloethane) were prepared and studied by means of thermogravimetry (TG/DTG) and differential thermal analysis (DTA) techniques. Their compositions were investigated by elemental analysis in order to ensure their purity and structural elucidations were based on conductivity measurements, room temperature magnetic measurements, proton NMR, XRD and IR spectra. Thermal decomposition of these distorted tetrahedral complexes and the ligand took place in two distinct steps upon heating up to 800°C, with the loss of inorganic and organic fragments. The thermal degradation of all the complexes (except for cadmium complex) in static air atmosphere started at temperatures lower than those observed for the free ligand pyrolysis. The composition of intermediates formed during degradation was confirmed by microanalysis and IR spectroscopy. The residues after heating above 740°C corresponded to metal oxide except for Hg(II) complex, which behaved differently. It was found on the basis of thermal analysis that thermal stability of the complexes increased in the following sequence: Hg(II)<Cu(II)<Cd(II).     

Determination of fluorine in solids down to 120 μg/g by wavelength dispersive X-ray fluorescence spectrometry

An X-ray fluorescence spectrometric method is described for the determination of fluorine from percent level down to 120 g/g in fluoropolymers and in fluoride samples. The method is based on the measurement of the intensity of first order line for 30 seconds using a flow proportional counter and a multilayer AXO6 crystal (2d=5.52 nm). The calibration curves of first degree base polynomials are linear over the concentration range of 8000–120 g/g and of 48.92–76% measured. The precision and accuracy obtained for polymer samples in percent level of fluorine are up to ±0.5 and within ±1%, respectively. However, the precision () for trace concentrations is in the range from 8 to 20%. In most cases the accuracy is up to ±7%, ±5% and ±4% in the concentration range of 120–8000 g/g, 801–8000 g/g and of 120–400 g/g, respectively. The time needed to analyze one sample including calibration and regression analysis is about 8 minutes.