Electrochemical oxidation of benzene to phenol

Gas-phase electrochemistry: The direct hydroxylation of benzene to phenol was investigated using an electrochemical cell. The production of phenol over a VO(x) anode was found to be significant at 50?°C. The resultant current efficiency for phenol production and selectivity toward phenol reached 76.5 and 94.7?%, respectively.     

Asymmetric induction in the preparation of helical receptor-anion complexes: ion-pair formation with chiral cations

Asymmetry through ion pairing: Upon addition of chloride and bromide ions, as chiral ammonium salts, to solutions of pyrrole-based π-conjugated linear oligomers, helical structures form with asymmetric induction, which is guided by the formation of diastereomeric ion pairs with chiral counter cations. These ions pairs exhibit circular dichroism (CD) and strong circularly polarized luminescence (CPL) with g(lum) values of greater than 0.1.     

Relationship between magnetic structure and ferroelectricity of systems with CuO2 ribbon chains

Results of experimental studies carried out by various methods on systems with CuO₂ ribbon chains are presented. For LiVCuO₄, which was found to have helimagnetic and ferroelectric simultaneous transitions (multiferroic transitions), the relationship between the magnetic structure and the ferroelectricity is described in detail by showing their magnetic field dependences. For Li₂ZrCuO₄, NMR studies have revealed that the system has ac-helical magnetic structure. However, we have not observed the ferroelectricity in this ordered phase. This result suggests that there may exist the antiferro-type ordering, for example, of the helical axis vectors, of the CuO₂ chains. Several new findings are also shown on the magnetic and dielectric properties of other ribbon chain systems, LiVCuO₄, Li₂ZrCuO₄, LiCu₂O₂ and NaCu₂O₂ and a related system Na₂Cu₃(GeO₃)₄.     

Switching in molecular shapes: main chain length driven rod-circle transition of isolated helical polysilanes

Unique conformations such as rod, semicircle, and circle structures of isolated semi-flexible helical polysilanes were observed by atomic force microscopy (AFM); the chain topology was significantly related to the chain length (molecular weight) on the surfaces.     

Study on the intermolecular interaction of C60 and simulations on the orientational properties of C60 in crystals

We developed the new intermolecular interaction model of C(60) with the quantitative accuracy for the molecular orientational properties in crystals. The energy difference (DeltaE) and the activation barrier (E(barrier)) between the two stable orientations (P and H orientations) in crystals are in the values of +14.7 and +260 meV in our model, respectively; these values are in fairly good agreement with the experimental values (DeltaE approximately +11 meV, E(barrier)=+235-+290 meV in experiments). The relaxation calculation for C(60) crystals using our model revealed that there is the reversal of the stable orientations between the P and H orientations under the high H-orientation occupancy (p(H)) in crystals, when p(H)>0.83, DeltaE<0. From the molecular dynamics calculations for C(60) crystals using our model, it is found that the phase transition is induced at T(C)=200-260 K, which is consistent with the experimental value of 260 K. Immediately below T(C), we found a great variety of molecular rotational jumps involving that between the P and H orientations every about 10(-9) s due to the thermal activation. In the high temperature phase (>T(C)), all molecules rotate irregularly like in Brownian motion involving the rotational "slumber" for approximately 10(-12)-10(-11) s.     

Global existence results for Oldroyd-B fluids in exterior domains

In this paper we consider the set of equations describing Oldroyd-B fluids in exterior domains. It is shown that these equations admit a unique, global solution defined in a certain function space provided the initial data and the coupling constant are small enough.     

Local Whittle likelihood estimators and tests for non-Gaussian stationary processes

In this paper, we propose a local Whittle likelihood estimator for spectral densities of non-Gaussian processes and a local Whittle likelihood ratio test statistic for the problem of testing whether the spectral density of a non-Gaussian stationary process belongs to a parametric family or not. Introducing a local Whittle likelihood of a spectral density f _θ (λ) around λ, we propose a local estimator [^(q)] = [^(q)] (l){\hat{\theta } = \hat{\theta } (\lambda ) } of θ which maximizes the local Whittle likelihood around λ, and use f_{[^(q)] (l)} (l){f_{\hat{\theta } (\lambda )} (\lambda )} as an estimator of the true spectral density. For the testing problem, we use a local Whittle likelihood ratio test statistic based on the local Whittle likelihood estimator. The asymptotics of these statistics are elucidated. It is shown that their asymptotic distributions do not depend on non-Gaussianity of the processes. Because our models include nonlinear stationary time series models, we can apply the results to stationary GARCH processes. Advantage of the proposed estimator is demonstrated by a few simulated numerical examples.     

Sorption and partial molar volumes of gases in poly(ethylene-co-vinyl acetate)

Sorption and dilation properties of polymer-gas systems involving poly(ethylene-co-vinyl acetate) and N₂, CH₄, or CO₂, have been investigated at pressures up to 50 atm at temperatures of 10–40°C. Sorption isotherms for low-solubility gases (i.e., CH₄ and N₂) can be described by Henry's law, and those for high-solubility gas (i.e., CO₂) by Flory-Huggins dissolution equation. Dilation isotherms are similar in contour to the corresponding sorption isotherms. From the obtained sorption and dilation data, partial molar volumes of the gases in the polymer were determined as a function of temperature. Thermal expansivity of dissolved CO₂ molecules was estimated at ca. 2.4 × 10^?3°C^?1 from the temperature dependence of partial molar volume. The expansivity is smaller than that of liquid CO₂ and larger than those of the polymer and organic liquids. © 1994 John Wiley & Sons, Inc.