cyanobacteria were collected and identified in five paddy fields with different soil textures of golestan province in iran. it was determined that nostoc ellipsosporum and nostoc muscorum were dominant in all sites among 20 species. to assess the ability of atmospheric nitrogen fixation by the species, their pure cultures were provided by growing on bg-11 solid culture medium. subsequently, eac...

Chemical vapor deposition was employed to synthesize carbon nanotubes with Ni-loaded MCM-41 and MCM-48 as catalysts and acetylene as precursor at 750°C. Mesoporous Ni MCM-41 and Ni MCM-48 molecular sieves were synthesized by a hydrothermal method and were characterized by XRD and N2 adsorption isotherm. The catalytically synthesized carbon materials were characterized with Raman spectroscopy, N...

Stratospheric measurements of acetylene up to altitudes of 30 km are presented. The air samples were collected during three different balloon flights, two of them at 44°N, one at nON using balloon borne, liquid neon-eooled, cryosamplers. Their acetylene concentration was measured in the laboratory by flame ionisation gaschromatography. The different profiles at nON and 44°N are discussed with r...

Nitrogen fixation (diazotrophy) has recently been demonstrated in several methanogenic archaebacteria. To compare the process in an archaebacterium with that in eubacteria, we examined the properties of diazotrophic growth and nitrogenase activity in Methanosarcina barkeri 227. Growth yields with methanol or acetate as a growth substrate were significantly lower in N(2)-grown cultures than in N...

The rate of acetylene reduction was measured as a function of time after addition of 10% acetylene in Alnus, Casuarina, Ceanothus, Datisca, and Myrica. The maximum rate occurred after 45 to 60 seconds and was maintained for an additional 0.5 to 4 minutes before a decline in rate to 30 to 90% of the maximum. The rate then recovered to a value of 63 to 98% of the maximum. Removal of the shoot and...

The atomic absorption of aluminum with air-acetylene flame was interfered by the formation of involatile compounds in the flame. Amines promoted the atomization of aluminum in the flame. Aluminum could be determined by atomic absorption spectrometry with an air-acetylene flame. The absorption of aluminum increased and then attained a constant value as the concentration of amines increased. The ...

The reaction of tellurium tetrachloride with acetylene proceeds in a stereospecific anti-addition manner to afford the novel products E-2-chlorovinyltellurium trichloride and E,E-bis(2-chlorovinyl)tellurium dichloride. Reaction conditions for the selective preparation of each of these products were found. The latter was obtained in 90% yield in CHCl(3) under a pressure of acetylene of 10-15 atm...

Nitrogen fixation (acetylene reduction) associated with roots of the seagrass Halodule wrightii was measured offshore near Beaufort and Moorhead City, N.C. Rates of acetylene reduction were higher in aerobic than in anaerobic assays and were linear for up to 5 days. The temperature range for acetylene reduction was 15 to 35 degrees C with a maximum activity at 35 degrees C. Nitrogenase activity...