The Navruz experiment: Cooperative monitoring for radionuclides and metals in Central Asia transboundary rivers

Summary This paper presents the results of radioecological investigation of Central Asian rivers.<Emphasis Type=Bold><Emphasis Type=Italic> </Emphasis></Emphasis>This work was done as part of the Navruz Project, a cooperative, transboundary river monitoring project involving rivers and institutions in Kazakhstan, Kyrgyzstan, Tajikistan, and Uzbekistan, and facilitated by Sandia National Laboratories in the United States. The study of waterborne radionuclides and metals concentrations in Central Asia is of particular interest because of the history of nuclear materials mining, fabrication, transport, and storage there, when it was part of the Soviet Union. This development left a legacy of radionuclides and metals contamination in some Central Asian regions, which poses a clear health hazard to populations who rely heavily upon surface water for agricultural irrigation and direct domestic consumption.     

Ruthenium complex catalyst system for selective oxidation of cyclohexane to cyclohexanone by molecular oxygen

Summary TS-1 zeolite was successfully synthesized <Emphasis Type=Italic>in-situ</Emphasis> on a honeycomb cordierite substrate. Cu-TS-1/cordierite and LaCu-TS-1/cordierite were used as catalysts for selective catalytic reduction (SCR) of nitrogen oxides (NOx) in the exhaust of lean burn engine. High catalytic activities were obtained and the main pollutants nitrogen oxides, carbon monoxide and hydrocarbons in the exhaust could be purified together.     

Catalytic degradation of polystyrene using HUSY catalysts

Summary The addition of carbon dioxide to phenyl glycidyl ether (PGE) was investigated in a semi-batch reactor using immobilized quaternary ammonium chloride catalysts. Five different catalysts were prepared with the following supports : (1) soluble poly(ST-<Emphasis Type=Italic>co</Emphasis>-VBC) [C1], (2) insoluble poly(ST-DVB-VBC) [C2], (3) macroporous poly(ST-DVB-VBC) [C3], (4) poly(ST-<Emphasis Type=Italic>co</Emphasis>-VBC)-MMT [C4] (5) modified MCM-41 [C5]. The addition of carbon dioxide to PGE can be considered as a pseudo-first order process with respect to the concentration of PGE. The pseudo-first order rate constant for the catalysts decreased in the series C1&gt;C3&gt;C2&gt;C4&gt;C5. The activation energy for C1 to C5 catalysts was 8.6, 20.9, 19.9, 23.9, and 26.8 kJ/mol, respectively. The immobilized catalysts can be reused in least 4 successive runs without any considerable loss of their initial reactivities.     

Characterization of the wavelength spectrum of guided neutron beams

Summary A simple method is introduced for the determination of the effective temperature of neutron beams. It is mathematically derived that the thermal equivalent neutron flux measured with a thin foil made from a 1/<Emphasis Type=Italic>v</Emphasis>-nuclide is proportional to the product of the real flux and the average wavelength. The real flux can be determined using fully absorbent materials. From the ratio of the two fluxes the average wavelength and the effective temperature can be determined. The method has been tested in thermal and cold neutron beams.