18 research outputs found
Chilling privation during dormancy period and carbohydrate mobilization in Japanese pear trees
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In situ laser raman spectroscopy during sequential oxidizing and reducing conditions for a vanadium-phosphorous-oxide catalyst
A VPO catalyst prepared in an organic medium has been studied by in situ laser Raman spectroscopy under reaction conditions for n-butane oxidation to maleic anhydride. Data were obtainable at low laser power and short collection times. Raman characterization during continuous flow (steady state) revealed that the (VO){sub 2}P{sub 2}O{sub 7} phase was present. Sequential oxidizing (10% O{sub 2} in N{sub 2}) and reducing (2% n-butane in N{sub 2}) conditions were explored at 350{degree} and 400{degree}C. Cycling (unsteady state) revealed enhancement of {alpha}{sub II}-VOPO{sub 4}, {beta}-VOPO{sub 4}, {gamma}-VOPO{sub 4}, and {delta}-VOPO{sub 4} during oxidizing conditions; intensity of Raman bands due to (VO){sub 2}P{sub 2}O{sub 7} increased during reducing conditions
The development of robust morphometric indices from accurate and precise measurements of free-swimming whale sharks using laser photogrammetry
Chromosome size and DNA content of species of anemone L. and related genera (Ranunculaceae)
Supported molybdena catalysts: Characterization of oxidized, reduced, and sulfided MoO3 prepared by an adsorption method
Chemical structural effects on γ-ray spectra of positron annihilation in fluorobenzenes
Spectra of γ-ray Doppler shifts for positron annihilation in benzene and
its fluoro-derivatives are simulated using low energy plane wave positron (LEPWP)
approximation. The results are compared with available measurements. It is found that the
Doppler shifts in these larger aromatic compounds are dominated by the contributions of
the valence electrons and that the LEPWP model overestimates the measurements by
approximately 30%, in agreement with previous findings in noble gases and small molecules.
It is further revealed that the halogen atoms not only switch the sign of the charges on
carbon atoms that they bond to, but that they also polarize other C-H bonds in the
molecule leading to a redistribution of the molecular electrostatic potentials. As a
result, it is likely that the halogen atoms contribute more significantly to the
annihilation process. The present study also suggests that, while the Doppler shifts are
sensitive to the number of valence electrons in the molecules, they are less sensitive to
the chemical structures of isomers that have the same numbers and type of atoms and,
hence, the same numbers of electrons. Further investigation of this effect is warranted