Unsteady and chaotic characteristics of natural convection field in vertical slots at large Prandtl number

In this study we examined the unsteady and chaotic characteristics of the natural convection field in vertical slots at large Prandtl number. In the computation, temperature dependence of viscosity was partially taken into consideration. As a result we discovered that the spatial region where a significant temperature fluctuation is detected corresponds to the spatial region where the secondary cells exist. The largest Lyapunov exponents calculated from the temperature on the center line have a local maximum at the lower region of the enclosure when the viscosity change was considered. These characteristics agree well with the experimental ones that have been observed by authors (Ishida, Kure and Kimoto 2001).     

Study on crystalline properties of Er-Si-O compounds in relation to Er-related 1.54 μm photoluminescence and electrical properties

Er-Si-O crystalline compounds, which exhibit superlattice structures and sharp and strong Er-related 1.54 μm photoluminescence (PL) spectra at room temperature have been formed by self-assembling growth mechanism. Oxidation of the starting materials which have Si and Er at an atomic ratio of 2:1 are prepared and then oxidation and succeeding high-temperature annealing in Ar above 1250 °C cause a self-assembled superlattice-structured Er-Si-O crystalline compounds. The control of the ratio of Si and Er, as well as the following oxidation and annealing processes, is found to be sensitive to the crystalline properties, PL spectra and electrical properties. In this study, Er-Si-O crystalline thin films are formed on Si substrates by sol-gel and MOMBE methods, and their crystalline properties such as crystalline orientation and concentration ratio of Er, Si and O are investigated. Crystalline Er-Si-O films of high orientation are successfully grown on Si(1 0 0) and its inclined surface. The PL and excitation spectra, fluorescence decay and the electrical properties are found to be strongly related to the crystalline properties. Excess O causes a broader 1.54 μm PL spectra, slower fluorescence decay, lower carrier-mediated excitation and higher resistivity. A precise control of O is found to be necessary to grow superlattice-structured Er-Si-O compounds, which are semiconducting and are excitable via carrier-mediated excitation mechanism.     

Light Diffraction of Aligned Polymer Fibers Periodically Dispersed by Phase Separation of Liquid Crystal and Polymer

We have confirmed light diffraction of aligned polymer fibers obtained by a phase separation of an anisotropic-phase solution of liquid crystal and polymer. He—Ne laser light passing through the polymer fibers was scattered in the axis vertical to the fibers, and had two peaks of light intensity symmetrical to the center of the transmitting laser spot. The two peaks were found to be caused by light diffraction due to the periodic polymer-fiber dispersion because the peaks corresponded to values calculated by intervals between the fibers. The periodical fiber networks are considered to be formed by anisotropic spinodal decomposition. This effect can be used to measure the dispersion order of the polymer fibers. © 2004 The Optical Society of Japan     

Studies on the syntheses of heterocyclic compounds. CLXXIV. An approach to the synthesis of oxyacanthine and berbamine

Schotten-Baumann reaction of the amine (X) with 4-benzyloxy-3,4′-oxydiphenylacetyl chloride (XI) gave two amides, (XIIa) and (XIIb), which were cyclized to give the corresponding 3,4-dihydroisoquinolines, respectively. Methylation of the above 3,4-dihydro-isoquinolines, followed by hydrolysis, afforded the compounds having the same composition as berbamine (Ia) and oxyacanthine (Ib), whose structures are under examination.     

Semiconducting organic polymer from polyacrylamide–Cu++ chelate and iodine

Semiconducting organic polymer was obtained by the modification of polyacrylamide (PAAm)–Cu⁺⁺ chelate with iodine in acetone. Favorable conditions for preparing the chelate effective for the conduction were investigated. Surface resistivities were affected by the amounts of cupric salts and iodine, satisfactory results being given by about 25 wt % of the salts based on PAAm and more than 1 wt % of iodine on the chelate. The conductivity was also varied with the degree of neutralization of the chelate in solution, and optimal values were obtained by addition of about an equimolar amount of potassium hydroxide to cupric salts. Effective structures of the polymer chelate in solution were assumed on the basis of the visible and the NMR spectra and potentiometric titration.     

Photopolymerization of methyl methacrylate in the presence of tertiary amines

The sensitization effect of tertiary amines on the photopolymerization of methyl methacrylate was studied. N,N-Dimethylbenzylamine, triethylamine, and N,N-dimethylaniline increased the rate of polymerization in this order, but pyridine did not show any effect. A free-radical mechanism was confirmed by the tacticity of polymer, the retarding effect of hydroquinone, and the copolymer composition with styrene. On the basis of the detailed kinetics of the sensitized polymerization and the ultraviolet spectra of the reaction mixtures, a sensitization mechanism is proposed, in which the excited monomer and the amine form a complex and generate an initiating radical.     

Studies on the syntheses of heterocyclie compounds. Part DXXVII.. the absolute configuration of 1,2,3,4-tetrahydro-1-phenylisoquinolines

The absolute configuraiton at the C₁-position of 1,2,3,4-tetrahydro-1-phenylisoquinolines can be deduced from the CD curves of either the free base or its methiodide. Furthermore, the absolute con figuration of (⁺)-2-amino-1-(3-hydroxyphenyl)ethanol (V) was revised and found to have R-configuration at the C₁ -position.     

Comparison of MBPT and coupled-cluster methods with full CI. Importance of triplet excitation and infinite summations

Results from full fourth-order perturbation theory [SDTQ MBPT(4)], and the coupled-cluster single- and double-excitation model (CCSD). are compared with recent full CI results for BH, HF, NH₃, and H₂O. For H₂O, studies include large symmetric displacements of the OH bonds, which offer a severe test for any single-reference MBPT/CC method. In every case. CCSD plus fourth-order triple-excitation terms provide agreement with the full CI to < 2 kcal/mole. SDTQ MBPT(4) has an error 10 kcal/mole for displaced H₂O.