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By combining a pulsed arc cluster ion source with a reflection time-of-flight mass spectrometer, we have produced and detected in situ fullerene cations as well as vanadium–carbon cluster cations. The cluster arrival time distributions favor the ‘‘fullerene road’’ mechanism for fullerene growth. The formation of fullerene cations was found to be strongly dependent on the discharge and nozzle conditions. Fullerene C+60/C+70 were preferentially produced by optimizing these conditions. Vanadium–carbon cluster cations were produced and detected by using a composite electrode (V2O5/graphite). While the metallocarbohedrene V8C+12 could be produced with a reasonable intensity, it was not dominant under our experimental conditions. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Reactions of excimer laser (XeCl, 308 nm) vaporized and excited fullerene C60 with La, Y, Eu, and Gd were carried out in mixtures of C60/La2O3, C60/Y2O3, C60/Eu2O3, and C60/Gd2O3. The reaction products M[ATOTHER]@xa[/ATOTHER]C60, M[ATOTHER]@xa[/ATOTHER]C60-2n and M[ATOTHER]@xa[/ATOTHER]C60+2m (M=La, Y, Eu, and Gd) were identified by a reflectron type time-of-flight mass spectrometer (RTOFMS). The products were subjected to reactions with H2O, O2, and N2O in a pick-up source. The metallofullerenes were found to be nonreactive toward H2O, N2O, and O2. This gives support to the endohedral nature of the metallofullerenes. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this paper, we report mass spectrometry studies on C[sub 2n]N[sub 5][sup -] cluster ions by collision-induced dissociation (CID). The mass-selected cluster ions were dissociated by collision with a crossed nitrogen beam and the fragment ions were mass analyzed in a secondary mass spectrometer. Characterization of the species as cyano-substituted, planar five-membered rings is supported by density functional theory (DFT) calculations. Based on the analysis of the experimental and computational results, cluster structures, energies, and stabilities are discussed. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A photochromism molecule, (E)-4-phenyl-1-(pyridine-2-ylmethylene)semicarbazide (1), was reported. Photochromism of 1 in solution was shown to result from the trans–cis photoisomerization of its C=N double bond, by using absorption, 1H NMR (including 2D NOESY) and directly the crystal structure of 1 obtained from solutions before and after UV irradiation. Photochromism of 1 in the solid state was found to take place, too, but via changes in the molecular geometry and packing upon UV irradiation. [ABSTRACT FROM AUTHOR]

Abstract: The porous hierarchical spherical Co3O4 assembled by nanosheets have been successfully fabricated. The porosity and the particle size of the product can be controlled by simply altering calcination temperature. SEM, TEM and SAED were performed to confirm that mesoporous Co3O4 nanostructures are built-up by numerous nanoparticles with random attachment. The BET specific surface area and pore size of the product calcined at 280°C are 72.5m2 g−1 and 4.6nm, respectively. Our experiments further demonstrated that electrochemical performances of the synthesized products working as an anode material of lithium-ion battery are strongly dependent on the porosity. [Copyright &y& Elsevier]

Stimulated by the recent preparation and characterization of the first [50]fullerene derivative, decachlorofullerene[50] (Science 2004, 304, 699), we have performed a systematic density functional study on the electronic and spectroscopic properties of C50, its anions and derivatives such as C50Cl10 and C50- Cl12. The ground state of C50 has D3 symmetry with a spheroid shape, and is highly aromatic; the best D5h C50 singlet is nonaromatic. Both D3 and D5h isomers of C50 have high electron affinities and can be reduced easily. Due to the unstable fused pentagon structural features, C50 is chemically labile and subject to addition reactions such as chlorination, d imerization and polymerization. The equatorial pentagon - pentagon fusions of D5h C50 are active sites for chemical reactions; hence, D5h C50 may behave as a multivalent group. The computed IR, Raman, 13C NMR and UV-vis spectra of the D5h C50C110 molecule agree well with the experimental data. Finally, D5h C50Cl10 is predicted to have a high electron affinity and, hence, might serve as an electron-acceptor in photonic/photovoltaic applications. The geometry and 13C NMR chemical shifts of C50Cl12 were computed to assist further isolation experiments. [ABSTRACT FROM AUTHOR]

Abstract: A uranyl nicotinate molybdate polymer [UO2(nicot)(MoO3OH)] n (Hnicot=nicotinic acid, NC5H4CO2H) was synthesized by the hydrothermal reaction of uranyl nitrate [UO2(NO3)2 ·6H2O], phosphomolybolic acid (H3PMo12O40) and nicotinic acid. Its crystal structure and fluorescent property were measured. The results show that the crystal packs in the 1D chains of uranyl molybdates with strong fluorescence at the range of 470–520nm. [Copyright &y& Elsevier]

A pre-driven double recovery room is widely used to safely remove longwall equipment in longwall coal mining. The stability of protective coal pillars is a crucial factor influencing surrounding rock deformation and failure in the pre-driven double recovery room. It is significant to characterize the loading mechanisms of protective coal pillars subjected to front abutment pressures to meet the enhanced design. In this study, surrounding rock deformation and protective coal pillar stress analysis of the recovery room are investigated through two case studies presented in the 15205 and 15206 panels of 5−2 coal seam at the Hongliulin Coal Mine in Shaanxi Province, China. It was observed that the surrounding rock deformation and protective coal pillar stress of the recovery room is quite different from adjacent panels of the same coal seam. It was also observed that the roof-to-floor convergence of the recovery room in the 15206 panel is 30% less comparison with 15205 panel and the increase in the protective coal pillar stress in the 15206 panel is 50% less comparison with 15205 panel. Further, the periodic weighting data and the failure form of the main roof have been analyzed after establishing an evaluation model for load estimation and derivation of the formula for evaluating the width of the protective coal pillar. It was noticed that the main roof break position has a significant impact on the width of protective coal pillars. It was also noticed that the critical width of the protective coal pillar in the recovery room of 5−2 coal seam is 23.8 m. The optimized protective coal pillar width is obtained applied in both the 15207 and 15208 panels and found that the stability of surrounding rock of the recovery rooms is ensured. [ABSTRACT FROM AUTHOR]