Authors:A. Yakushev, S. Timokhin, M. Vedeneev, Xu Honggui, and I. Zvara
An isotope of element 106, namely263106, detected by its spontaneous fission, has been chemically isolated by thermochromatography of oxochlorides. The last one has been compared with short- and long-lived isotopes of Mo and W. Two chemical species were observed, presumably MO2Cl2 and MOCl4 (M=Mo,W). A kinetic dependence of these two species has been discussed and a chemical form O2Cl2 has been described for the registered atoms of element 106.
Authors:X. Feng, S. Lo, G. Ji, Y. Jiang, and Y. Xu
The production rates (numbers of atoms per gram of the respective elements per second) of 40 radioactive nuclides of 34 elements by neutron capture reactions in a reactor were determined from about 130 photopeaks of the -ray spectra. The ratios of these production rates were called R-matrix elements. These production rates and the respective thermal neutron capture cross sections were used to calculate the respective apparent neutron fluxes at the position of irradiation and the -matrix elements which were the ratios of these apparent neutron fluxes. These matrix elements express clearly the correlations among various elements and thus may be used in the mono-standard or small-number-standards method in neutron activation analysis.
Authors:L. Hulett, Jun Xu, S. McLuckey, and D. Schrader
A review is given of the ionization of organic moecules by monoenergetic positrons having energies in the range of 0.5–15 eV. Two mechanisms, unique to positrons, are described. If the kinetic energy of the positron is above the positronium formation threshold, such that electrons can be removed from the molecules to form free positronium atoms, the ionization/fragmentation behavior can be explained qualitatively by a modification of the Ore gap theory. To explain how positrons can ionize and fragment molecules when their kinetic energies are below the positronium formation threshold, it is necessary to assume that energy is transferred to the molecule by the annihilation process. Ionization cross sections for positrons having kinetic energies below the positronium formation threshold are sensitive to molecular size, structure and bond types. Continuing work involves a search for positronium compound formation and measurements of the kinetic energy distributions of ions.
Authors:X. Zheng, T. Kawae, S. Tanaka, M. Suzuki, and C. Xu
Heat capacity measurements were carried out on single-crystalline CuO in the temperature range 130–300 K. Sharp peaks corresponding to the antiferromagnetic transitions were clearly observed at 211 and 227 K. At the low-temperature end, near 160 K, a wide peak in the heat capacity signal was also demonstrated. An electric anomaly was observed in the temperature range 150–160 K, which strongly suggests the possibility of a new low-temperature phase transition in CuO. This study also indicates that DSC measurement is an effective tool to detect magnetic transitions and probe subtle phase transitions in solids.
Authors:S. Timokhin, A. Yakushev, Honggui Xu, V. Perelygin, and I. Zvara
For the first time the chemical identification of element 106 was accomplished. The Gas-thermochromatographic experiments with an oxochloride of element 106 are described. Reproducible zones of tracks of fission fragments were observed in the temperature region of 150–250°C. The chemical behavior of element 106 oxochloride is similar to that of the tungsten compound.
Authors:S. Lahiri, X. Wu, Yang Weifan, Xu Yanbing, and Yuan Shuanggui
Liquid liquid extraction of 46Sc was studied with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP). It has been found that PMBP extracts almost quantitatively scandium from 10-3 to 10-2M HCl solutions. Tributyl phosphate (TBP) has a pronounced antagonistic effect on the extraction process.
Authors:W. Jester, T. Daubenspeck, S. Pandey, and X. Xu
Personnel from the Pennsylvania State University's Breazeale Nuclear Reactor assisted NRC (Nuclear Research Corporation) personnel in calibrating a new MSL/16N Nitrogen-16 Monitor. This paper describes the neutron flux calibration procedures utilized and the results obtained for the production of a nitrogen-16 source of known activity for a BGO detector calibration.
Authors:Weijuan Jia, Jessica McLachlan, Jiayan Xu, and S. Eichhorn
Gold nanoparticles (Au-NPs) were prepared by a surfactant-free single-phase reduction of hydrogen tetrachloroaurate(III) hydrate
in the presence of different organic thiol ligands. Sizes, size distributions, and crystallinity of the Au-NPs were determined
by high-resolution transmission electron microscopy and powder X-ray diffraction, whereas thermogravimetric analysis provided
information on the organic ligand-to-gold ratios as well as amounts of contaminants. A systematic decrease in size with increasing
conical bulk of the thiolate ligand is observed but large size distributions and contamination of the generated Au-NPs prohibit
detailed mechanistic studies. A first-generation Fréchet dendron thiol produced the smallest and cleanest Au-NPs of the narrowest
It has been generally accepted when estimating sedimentation rates using the 137Cs dating method that the position of the 137Cs maximum in a sediment profile represents the year 1963. In this paper we validated this approach by developing a model
in which the annual 137Cs global fallout flux for the Yangtze River estuary was established on the basis of the Tokyo flux corrected for precipitation
rates observed in Shanghai. As the 137Cs maxima in the sediment deposition profiles depend on the sedimentation rates, the sub-sampling intervals were calculated
accordingly. Higher measured than the calculated values were found in some cores, what may be due to fluctuating sedimentation
rates and an additional deposition of 137Cs from land-based sources. The study provides useful information on the reliability of the measured 137Cs maxima in sediment profiles frequently used for dating of sediments in marine (coastal regions, open seas) as well as in
terrestrial (lakes) environments.
Conducting polyaniline/Cobaltosic oxide (PANI/Co3O4) composites were synthesized for the first time, by in situ deposition technique in the presence of hydrochloric acid (HCl)
as a dopant by adding the fine grade powder (an average particle size of approximately 80 nm) of Co3O4 into the polymerization reaction mixture of aniline. The composites obtained were characterized by infrared spectra (IR)
and X-ray diffraction (XRD). The composition and the thermal stability of the composites were investigated by TG-DTG. The
results suggest that the thermal stability of the composites is higher than that of the pure PANI. The improvement in the
thermal stability for the composites is attributed to the interaction between PANI and nano-Co3O4.