Facile palladium-catalysed synthesis of 1-aryl-1H-indazoles from 2-bromobenzaldehydes and arylhydrazines

2-Bromobenzaldehydes react with arylhydrazines in toluene at 100 [degree]C in the presence of a catalytic amount of a palladium catalyst and phosphorus chelating ligands such as 1,1[prime or minute]-bis(diphenylphosphino)ferrocene and 1,3-bis(diphenylphosphino)propane along with NaO-t-Bu to afford 1-aryl-1H-indazoles in good yields.     

Mid-infrared light emission characteristics of Ho3+-doped chalcogenide and heavy-metal oxide glasses

Emission characteristics of Ho³⁺-doped heavy-metal oxide and chalcogenide glasses were investigated and compared with those of conventional oxide glasses. In addition to the fluorescence at approximately 1.2 m (5/6 5/8) and 2.0 m (5/7 5/8), another mid-infrared emission was observed at 2.9 m from the transition 5/6 5/7. The calculated radiative transition probability and multiphonon decay rate of the latter transition using Judd-Ofelt analysis indicated that the occurrence of the 2.9 m fluorescence was directly related to the low vibrational phonon energy of the host glasses.     

Numerical solution of one-dimensional Burgers’ equation using reproducing kernel function

This paper presents a numerical method for one-dimensional Burgers’ equation by the Hopf–Cole transformation and a reproducing kernel function, abbreviated as RKF. The numerical solution is given as explicit integral expressions with the RKF at each time step, so that the computation is fully parallel. The stability and error estimates are derived. Numerical results for some test problems are presented and compared with the exact solutions. Some numerical results are also compared with the results obtained by other methods. The present method is easily implemented and effective.     

Electron electric dipole moment induced by octet-colored scalars

An appended sector of two octet-colored scalars, each an electroweak doublet, is an interesting extension of the simple two Higgs doublet model motivated by the minimal flavor violation. Their rich CP violating interaction gives rise to a sizable electron electric dipole moment, besides the quark electric dipole moment via the two-loop contribution of Barr–Zee mechanism.     

The Effect of ζ‐Potential and Hydrodynamic Size on Nanoparticle Interactions in Hydrogels

The ζ‐potential and hydrodynamic size (d_h) of nanoparticles (NPs) are systematically controlled by capping gold NPs (AuNPs) with polymers having different charges and treating them in NaCl solutions of diverse concentrations. Interactions between AuNPs in hydrogel are caused by chemical reactions induced by 1,4‐dithiothreitol. The effect of ζ‐potential is clear, as negatively charged AuNPs can be aggregated in neutral agarose gel, but the amount of aggregation is significantly affected by the magnitude of the negative surface charge on the AuNPs. However, all positively charged AuNPs show negligible aggregation in agarose gel with slightly negative polarity. The effect of d_h on AuNP aggregation is different from that of ζ‐potential. Although AuNPs with small d_h generally show more aggregation than those with large d_h, the amount of AuNP capping layer is critical. Thus, the amount of polymer present on NP surface needs to be considered to investigate the effect of d_h on AuNP aggregation. Through extended Derjaguin, Landau, Verwey, Overbeek (XDLVO) theory, it is shown that the charges of the AuNPs and the hydrogel, as well as the d_h of the NPs, are related to electrostatic repulsion and steric hindrance, which affect AuNP aggregation in hydrogel.     

Heterodyne-detected fifth-order nonresonant Raman scattering from room temperature CS2

Actively phase-locked heterodyne-detected fifth-order nonresonant Raman scattering from room temperature CS2 has been measured. The experimental signals have similar magnitudes, shapes, and sign changes as calculated responses obtained via molecular dynamics simulations [S. Saito and I. Ohmine, Phys. Rev. Lett. 88, 207401 (2002)]. The measured signals contain sign changes that appear to be associated with the coupling of rotational motions both to each other and to translational motions.     

Synthesis of a water-soluble fullerene [C60] under ultrasonication

A water-soluble fullerene [C60] is prepared with fullerene [C60] and a mixture of strong inorganic acids at the ratio (v/v) of 3:1 under ultrasonic condition at 25-43 degrees C. The MALDI-TOF MS and 13C-NMR spectra confirmed that the product of a water-soluble fullerene compound was C60.     

UV photoresponse of single ZnO nanowires

ZnO nanowires grown by site-selected molecular beam epitaxy (MBE) were contacted at both ends by Al/Pt/Au ohmic electrodes. The current–voltage (I–V) and photoresponse characteristics were obtained both in the dark and with ultraviolet (UV, 254 or 366 nm) illumination. The I–V characteristics are ohmic under all conditions, with nanowire conductivity under UV exposure of 0.2 cm. The photoresponse showed only a minor component with long decay times (tens of seconds) thought to originate from surface states. The results show the high quality of material prepared by MBE and the promise of using ZnO nanowire structures for solar-blind UV detection. PACS 81.05.Dz; 73.61.Ga; 72.80.Ey     

Hydrogen and ozone gas sensing using multiple ZnO nanorods

ZnO nanorods grown by site-selective molecular beam epitaxy show current–voltage characteristics that are sensitive to the presence of hydrogen or ozone in the measurement ambient for temperatures as low as 112 °C for H₂ or room temperature for O₃. The sensitivity to hydrogen increases sharply with temperature and multiple nanorods contacted at both ends by ohmic electrodes show currents of 10^-8 A at 200 °C and a differential current change of 18% when changing from a pure N₂ ambient to 10% H₂ in N₂. The nanorods are able to detect small concentrations (3%) of O₃ in O₂, with changes in current of 10^-7 A at 25 °C. The sensitivity was 21% for O₃ at room temperature. The nanorods also show a strong response to above-band-gap illumination with ultraviolet light. PACS 81.05.Dz; 73.61.Ga; 72.80.Ey