Observation of the Hadronic transitions chi(b1,2)(2P)-->omegaUpsilon(1S)

The CLEO Collaboration has made the first observations of hadronic transitions among bottomonium (bbmacr;) states other than the dipion transitions among Upsilon(nS) states. In our study of Upsilon(3S) decays, we find a significant signal for Upsilon(3S)-->gammaomegaUpsilon(1S) that is consistent with radiative decays Upsilon(3S)-->gammachi(b1,2)(2P), followed by chi(b1,2)(2P)-->omegaUpsilon(1S). The branching ratios we obtain are B[chi(b1)(2P)-->omegaUpsilon(1S)]=(1.63(+0.35+0.16)(-0.31-0.15))% and B[chi(b2)(2P)-->omegaUpsilon(1S)]=(1.10(+0.32+0.11)(-0.28-0.10))%, in which the first error is statistical and the second is systematic.     

Wess-Zumino current and the structure of the decay tau- -->K- pi- K+ nu tau

We present the first study of the vector (Wess-Zumino) current in tau(-)-->K-pi-K+nu(tau) decay using data collected with the CLEO III detector at the Cornell Electron Storage Ring. We determine the quantitative contributions to the decay width from the vector and axial vector currents. Within the framework of a model by Kühn and Mirkes, we identify the quantitative contributions to the total decay rate from the intermediate states omegapi, rho(')pi, and K*K.     

Mott domains of bosons confined on optical lattices

In the absence of a confining potential, the boson-Hubbard model exhibits a superfluid to Mott insulator quantum phase transition at commensurate fillings and strong coupling. We use quantum Monte Carlo simulations to study the ground state of the one-dimensional bosonic Hubbard model in a trap. Some, but not all, aspects of the Mott insulating phase persist. Mott behavior occurs for a continuous range of incommensurate fillings, very different from the unconfined case, and the establishment of the Mott phase does not proceed via a traditional quantum phase transition. These results have important implications for interpreting experiments on ultracold atoms on optical lattices.     

Combination of glow-discharge and arc plasmas for CF4 abatement

Decomposition of CF₄ by glow-discharge and arc plasmas was studied using a tubular quartz reactor, a disk type, and a T-type quartz reactor. The effects of different metal electrodes, input voltage, and reactor type on the efficiency of CF₄ total destruction (DRE) were studied. The T-shape reactor was more efficient in CF₄ destruction than either the disk or tubular type due to a combined effect of glow discharge and arc plasmas. Several hydrogen and oxygen sources, such as H₂O, H₂, O₂, and CH₄, were used to convert CF₄. Using H₂ and O₂ as the hydrogen and oxygen sources presented better DRE than using H₂O. The effect of different hydrogen and oxygen sources on the conversion of CF₄ followed the trend: (H₂ + O₂) > (CH₄ + O₂) > H₂O. The maximum DRE of 95% was observed with 0.5% CF₄ using H₂ and O₂. A mass spectrometer and an emission spectroscope equipped with a charge-coupled detector (CCD) were used to characterize the products and intermediates. Mass spectrometric studies indicated that the reaction products were HF, CO₂, and trace amounts of NO. N₂ first negative and second positive emission lines were observed in the glow discharge plasmas as well as in the arc plasmas of N₂. However, C and F intermediates were observed only in arc plasmas of CF₄. Reactions occurring in the glow discharge plasmas and arcs seem to follow different mechanisms.     

Fundamental photoluminescence properties of pyrene carbonyl compounds through absolute fluorescence quantum yield measurement and density functional theory

We reviewed the photophysical properties of carbonyl-functionalized pyrene derivatives [i.e., pyrene with aldehyde (PA: 1-formylpyrene), ketone (PK: 1-acetylpyrene), carboxylic acid (PCA: 1-pyrenecarboxylic acid), and ester groups (PE: 1-methoxycarbonylpyrene)] using a measurement of absolute fluorescence quantum yield in various solvents and time-dependent density functional theory (TD-DFT) calculations. Here, we obtained new important data that fill in the gaps in existing datasets on these properties and help identify photoluminescence mechanisms. The results of the TD-DFT calculations were in agreement with the experimental results, and indicated that the low fluorescence of PA and PK is derived not only from intersystem crossing but also from internal conversion due to the proximity effect; this inference was also supported by the measurements of the photoluminescence spectra at low temperatures. In addition, factors leading efficiently to non-radiative processes were shown to be absent in PCA and PE. Thus, we successfully revised and systematized the photophysical properties of pyrene modified by carbonyl substitutes, including carboxamide groups, which were previously reported by us. Moreover, we showed that the photoluminescence properties of such compounds might be predictable by using TD-DFT calculations.     

Proton conduction properties of nano-titania modified by sulfuric acid impregnation

The proton conduction properties of sulfuric acid-modified nano-titania prepared by impregnation method were investigated. The proton conductivity of sulfuric acid-modified nano-titania was almost the same as that of hydrous sulfated nano-titania investigated in our previous work when the amount of adsorbed sulfate groups was almost the same. The highest conductivity was obtained at an adsorbed sulfate group amount of 0.42?mmol/g, not 0.97?mmol/g. This result indicates that the enhancement of conductivity with increasing amount of adsorbed sulfate groups is limited. This might be attributable to insufficient water molecule adsorption on the Ti⁴⁺ site coordinated with a bidentate sulfate group due to the prevention by excess sulfuric acid.     

Direct observation of the formation of a cyclic poly(alkyl sorbate) via chain-growth polymerization by an N-heterocyclic carbene initiator and ring-closing without extreme dilution

1,3-Di-tert-butylimidazol-2-ylidene (NHCtBu), which is one of the typical N-heterocyclic carbene (NHC), was found to initiate the anionic chain-growth polymerization of methyl sorbate (MS) in toluene at −20°C. The polymerization was accelerated by an aluminum Lewis acid, that is, methylaluminum bis(2,6-di-tert-butyl-4-methylphenoxide) (MAD), to afford cyclic poly(MS)s. Subsequently, thiol-ene click reactions of poly(MS)s with two different alkanethiols were performed using a photoradical initiator to obtain graft-like polymers, which was for the microscopic observation of the chains directly by transmittance electron microscope (TEM). The contamination of linear polymers was hardly observed. This means that the polymers synthesized by our synthetic strategy were indeed cyclic polymers. We also compared the theoretical and experimental chain diameter and width for the graft-like cyclic polymers, where these values were dependent on the molecular weight of the cyclic polymers regulated by the feed monomer/initiator ratio and length of the alkanethiols, respectively.     

Observation of the h(c)(1P) Using e+ e- collisions above the DD threshold

Using 586 pb(-1) of e+ e- collision data at E(c.m.) = 4170 MeV, produced at the Cornell Electron Storage Ring collider and collected with the CLEO-c detector, we observe the process e+ e- → π+ π- h(c)(1P). We measure its cross section to be 15.6±2.3±1.9±3.0 pb, where the third error is due to the external uncertainty on the branching fraction of ψ(2S) → π0 h(c)(1P), which we use for normalization. We also find evidence for e+ e- → ηh(c)(1P) at 4170 MeV at the 3σ level and see hints of a rise in the e+ e- → π+ π- h(c)(1P) cross section at 4260 MeV.     

Phase transition in the family LaxBi4−xTi3O12: In relation to lattice symmetry and distortion

The ferroelectric phase transition in the family La_xBi_4?xTi₃O₁₂ was investigated by X-ray diffractometry and differential scanning calorimetry. The crystal symmetry is orthorhombic in the range of 1 > x ≥ 0 and tetragonal in x ? 1. It was found that the shift of the phase-transition temperature is closely related to crystallographic symmetry and lattice distortion. (1) As the value of x increases, the ratio of lattice parameters, $\text{a}\text{b}$, decreases toward 1. (2) In the range of 1 > x ≥ 0, the lattice distortion increases with increasing x; just before x exceeds about 1, the distortion reaches a maximum. (3) As x exceeds about 1, the distortion decreases distinctively. (4) In the orthorhombic region, the phase-transition temperature decreases with increasing x. (5) In the tetragonal region, the transition does not occur. (6) The relation of transition temperature T_c to x is represented by a nonlinear function.     

Synthesis of 3-cyano-2-methylpyridines substituted with heteroaromatics

A series of title compounds were easily prepared by the sonication of α,β-unsaturated carbonyl compound in acetonitrile in the presence of potassium t-butoxide.