Measurement of branching fractions and polarization in B-->phiK(*) decays

We present the first measurement of decay amplitudes in B-->phiK* and measurements of branching fractions in B-->phiK(*) decays based on 78.1 fb(-1) of data recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- storage ring. The decay amplitudes for the different phiK*0 helicity states are measured from the angular distributions of final state particles in the transversity basis. The longitudinal and transverse complex amplitudes are |A0|2=0.43+/-0.09+/-0.04, |A(perpendicular)|2=0.41+/-0.10+/-0.04, arg((A(parallel))=-2.57+/-0.39+/-0.09, and arg((A(perpendicular))=0.48+/-0.32+/-0.06. The direct CP-violating asymmetries are found to be consistent with zero.     

Measurement of the electroweak penguin process B-->X(s)l+l-

We report the first measurement of the branching fraction for the inclusive decay B-->X(s)l(+)l(-), where l is either an electron or a muon, and X(s) is a hadronic recoil system that contains an s quark. We analyzed a data sample of 65.4 x 10(6) B meson pairs collected with the Belle detector at the KEKB e(+)e(-) asymmetric-energy collider. We find B(B-->X(s)l(+)l(-))=[6.1 +/-1.4(stat) +1.4-1.1(syst)] x 10(-6) for dilepton masses greater than 0.2 GeV/c(2).     

Absolute frequency measurement of an acetylene-stabilized laser at 1542 nm

The absolute frequency of an acetylene-stabilized laser at 1542 nm is measured at its second harmonic (771 nm) by use of a femtosecond optical comb based on a mode-locked Ti:sapphire laser. Frequency stability and reproducibility of the acetylene-stabilized laser are evaluated by the femtosecond comb with a H maser as a frequency reference. The absolute frequency of a laser diode stabilized on the P(16) transition of 13C2H2 is determined to be 194 369 569 383.6(1.3) kHz. The acetylene-stabilized laser serves as an important optical frequency standard for telecommunication applications.     

Ferroelectric switching characteristics of 73/27 copolymer of vinylidene fluoride and trifluoroethylene

Ferroelectric polarization-reversal switching of vinylidene fluoride—trifluoroethylene copolymer with 73 mol % of vinylidene fluoride is investigated under a variety of conditions in an attempt to derive detailed information on the polarization reversal of the polymer. The electric-field dependence of switching time t_s obeys an exponential law. The temporal change of switching current density J is presented in the form J/(P_s ? P) versus time (P is the polarization, and P_s is its saturation value), which is free of the depolarization-field effect and discriminates in a straightforward manner between acceleration and deceleration of switching. Effects of the annealing of samples upon t_s are observed together with changes in the degree of crystallinity. Effects of space charge distribution upon t_s are investigated by applying two successive pulses, positive and negative, with varied intervals t_w between the two. The dynamics of space charge redistribution is elucidated from the t_w dependence of the t_s of the second pulse. The temperature dependence of t_s indicates that the switching becomes critically fast as the phase-transition temperature is approached.     

Impact parameter analysis of KN and πN scattering in the intermediate energy region

We have evaluated the s-channel-helicity partial-wave amplitudes for $\text{K}\text{N and πN}$ scattering as functions of the impact parameter using partial-wave data in the energy range P_L≈1.0–2.0 GeV/c. We find that the $\text{K}\text{N}$ background and resonance amplitudes exhibit features consistent with the dual absorptive picture for pomeron and f + ω and A₂ + ? exchanges. Comparison of the πN low-energy amplitude with the partial-wave decomposition of a quantitative Regge model gives evidence for local duality between the s-channel resonance and t- and u-channel Regge exchanges.     

Molecular orbital quantities of conjugated ketenes and influence of structural variations on their electronic features

MO quantities by CNDO/2 method on several valence isomeric ketenes and structurally corresponding allene molecules were calculated to evaluate the influence of structural feature on magnitude of back-donation of oxygen n-electrons in ketene, and to rationalize an unusual cycloaddition involved in diphenyl ketene.     

Selective Homonuclear Polarization Transfer in the Tilted Rotating Frame under Magic Angle Spinning in Solids

An application of the R2TR method (1995,Chem. Phys. Lett.232,424) to selective homonuclear polarization transfer under magic angle spinning is proposed. It is shown that, for a spinning speed fast enough to remove the maximum homonuclear dipolar coupling constant ω_Dinvolved, the flip-flop and flop-flop mechanisms are suitable for recoupling the spins with a chemical shift difference larger than ω_Dand a difference comparable to or smaller than ω_D, respectively. It is also shown that, for fast polarization transfer, the off-resonance frequencies should be much higher than the RF intensity in the flip-flop condition, while for the flop-flop condition, the off-resonance frequencies should be much lower than the RF intensity. Some one- and two-dimensional experiments are proposed by utilizing the capability of the R2TR method to abruptly switch on and off the recoupling condition, and are demonstrated for triply¹³C-enriched -alanine. The mixing time required for population transfer was found to be ca. 0.5 ms for the methine and methyl¹³C spins separated by 1.5 Å and ca. 5 ms for the methyl and the carboxyl carbons separated by 2.5 Å. The experimental results and theoretical simulations show that selective polarization transfer is achieved when the difference in the isotropic chemical shifts between the relevant pair of spins and a neighboring spin is more than 1000 Hz.     

Preparation of ketones by direct reaction of grignard reagents with acid chlorides in tetrahydrofuran

Grignard reagents react with acid chlorides in tetrahydrofuran at low temperature to produce ketones in excellent yields. The results reported here strongly indicate the importance of the solvent in Grignard reagent chemistry.     

Errata

A tunable high power subpicosecond pulse laser with a peak power of more than 1 GW, pulse width of 0.8 ps in the near IR region has been realized. Details of the characteristics of the amplified spontaneous emission and amplification of the laser light in this system are described.     

Hydroxylation of aromatic rings in an aqueous solution induced by argon arc plasma

Plasma-induced reaction in an aqueous solution of phenyl-containing amino acids resulted in the formation of several hydroxyphenyl amino acids, which was explained by the action of hydroxyl radicals generated by decomposition of water molecules by the high energy plasma.