The effect of ultraviolet-B (280 to 320 nm) irradiation on physiological activities of Anabaena flos-aquae and the water fern Azolla caroliniana has been studied under conditions where lethal effects of irradiation are absent. Nitrogenase activity, measured as acetylene reduction, specifically declined during irradiation with low levels of ultraviolet-B, whereas other physiological activities w...

The reduction of nitrogen, acetylene, azide, and cyanide at various oxygen concentrations by nitrogenase from Azotobacter vinelandii was measured with a well-defined system. Oxygen inhibited the reduction of each substrate uncompetitively. The inhibition constants (K(i)) were 0.014, 0.023, 0.008, and 0.003 atm of oxygen for reduction of nitrogen, acetylene, azide, and cyanide, respectively. The...

Rotationally resolved gas-phase absorption spectra of partially and fully deuterated linear seven-carbon chain radicals are presented in this article. The carbon-based molecules are generated in a supersonically expanding planar plasma by discharging a gas mixture of acetylene and deuterium-enriched acetylene in helium and argon. Spectra are recorded in direct absorption using cavity ring-down ...

Anion photoelectron spectra are presented for the halide-acetylene complexes, X– · · · C2H2 where X = Cl, Br, and I. Electron binding energies are determined to be 4.1, 3.8 and 3.4 eV respectively. Results from CCSD(T) calculations are presented for the neutral halogen-acetylene complexes. Two minima are predicted corresponding to a linear C∞v and T-shaped C2v geometry, with the T-shaped geomet...

Recent developments in the synthesis of CuO nanoparticles (NPs) and their application to the [3+2] cycloaddition of azides with terminal alkynes are reviewed. With respect to the importance of click chemistry, CuO hollow NPs, CuO hollow NPs on acetylene black, water-soluble double-hydrophilic block copolymer (DHBC) nanoreactors and ZnO–CuO hybrid NPs were synthesized. Non-conventional ene...

The harmonically coupled anharmonic oscillator model developed by Child and co-workers is extended to treat the coupling of two doubly degenerate “local benders” as may be expected in acetylene. This effective Hamiltonian is transformed to the normal mode representation and a set of “x-K ” relations derived that relate the anharmonic and Darling-Dennison-type resonance terms to the diagonal loc...

Optimized geometries and adsorption energies obtained from non-local density functional calculations are presented for the adsorption of acetylene and ethylene on Ni(lll). Two cluster models, Ni4 and Nil4, are used. The best adsorption modes are #bridging and di-cr for acetylene and ethylene, respectively. In these orientations the overlap between the adsorbate frontier orbitals and the metal c...

The competition between rearrangement of the excited allyl radical via a 1,3 sigmatropic shift versus sequential 1,2 shifts has been observed and characterized using isotopic substitution, laser excitation, and molecular beam techniques. Both rearrangements produce a 1-propenyl radical that subsequently dissociates to methyl plus acetylene. The 1,3 shift and 1,2 shift mechanisms are equally pro...