Molecular motion of syndiotactic poly(α-methylstyrene) in solution studied by carbon-13 n.m.r. relaxation measurements

The carbon-13 n.m.r. spin-lattice relaxation times, nuclear Overhauser enhancement factor (NOE), and line widths have been measured for a syndiotactic poly(α-methylstyrene) in solutions in toluene-d₈ and o-dichlorobenzene-d₄ as a function of temperature from 40° to 163δC. The single correlation time model of relaxation is inadequate to explain the data of spin-lattice relaxation time and NOE. But, within experimental error, these relaxation data in two solvents over a full temperature range can be interpreted in terms of either the Cole-Cole or the log-χ² distributions of correlation times, or a conformational jump model proposed by Monnerie et al. The internal rotation of the methyl group is relatively rapid, while that of the phenyl ring is slow and practically overshadowed by the backbone segmental reorientation over the temperature range examined. The solvent dependence of relaxation data was discussed.     

Phase transitions in R2 SnCl6-type crystals (R = NH3 C2H3, NH3C2H5 and N(CH3)4)

The thermal dilatation in (NH₃ ·CH₃) SnCl₆, (NH₃ · C₂H₅) SnCl₆ and [N(CH₃)] SnCl₆ was measured, and as the results it has turned out that (NH₃ ⁶·C₂H₅) SnCl₆ and [N(CH₃)₄]₂ SnCl₆ undergo the first order transitions at 128 K and 158 K, respectively. The low temperature phases of (NH · C₂H₅) SnCl₆ and [N(CH₃)₄]₂ SnC1₆ are found to be monoclinic and tetragonal, respectively, No phase transition was observed in (NH₃ ·CH₃)₂ SnCl₆ down to 77 K.     

Selective synthesis of isobutene trimers and hexamers with oxo acid catalysts

The reaction of isobutene (IB) with its dimers (IB₂) catalyzed by CF₃SO₃H yielded isobutene trimers (IB₃) in high yield in nonpolar solvents at 0°C. The initial feed of isobutene, in the presence of equimolar IB₂ or more, was selectively converted into IB₃ without loss or accumulation of IB₂. After complete consumption of the isobutene, however, the remaining IB₂ rapidly dimerized to isobutene tetramers (IB₄). ¹³C-NMR analysis of the products showed that the IB₃ was formed via addition of the t-butyl cation (protonated isobutene to 2,4,4-trimethyl-1-pentene (an IB₂ isomer); the trimer fraction was free from isomers arising from addition of the t-butyl cation to 2,4,4-trimethyl-2-pentene (another IB₂ isomer) or addition of the IB₂ cation to isobutene. The IB₃ thus obtained was further oligomerized with CF₃SO₃H catalyst in nonpolar media in the range of 0 to ?25°C to give a mixture of IB₅, IB₆, and IB₇ in high yield. With EtAlCl₂ as catalyst, reaction of isobutene with IB₂ and oligomerization of IB₃ both resulted in products with a broad molecular weight distribution containing higher oligomers and complex hydrocarbons formed via cracking of the intermediate carbocations.     

High-performance C60 and picene thin film field-effect transistors with conducting polymer electrodes in bottom contact structure

C₆₀ and picene thin film field-effect transistors (FETs) in bottom contact structure have been fabricated with poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) electrodes for a realization of mechanical flexible organic FETs. The C₆₀ thin film FETs showed n-channel enhancement-type characteristics with the field-effect mobility μ value of 0.41 cm² V^?1 s^?1, while the picene thin film FET showed p-channel enhancement-type characteristics with the μ of 0.61 cm² V^?1 s^?1. The μ values recorded for C₆₀ and picene thin film FETs are comparable to those for C₆₀ and picene thin film FETs with Au electrodes.     

High Mobility and Luminescent Efficiency in Organic Single‐Crystal Light‐Emitting Transistors

A high‐performance ambipolar light‐emitting transistor (LET) that has high hole and electron mobilities and excellent luminescence characteristics is described. By using this device, a conspicuous light‐confined edge emission and current‐density‐dependent spectral evolution are observed. These findings will result in broader utilization of device potential and they provide a promising route for realizing electrically driven organic lasers.     

Production of Xylanase with a transformant of Aspergillus oryzae RIB40 in a Liquid-Surface Immobilization (LSI) System

Xylanase production by a XynF1 (33 kDa)-transformant of Aspergillus oryzae RIB40 was compared between submerged cultivation (SmC) and liquid-surface immobilization (LSI) systems. While the accumulation of xylanase in the SmC decreased by prolonged incubation, LSI system enabled the continuation of xylanase production to afford 4.5-fold xylanase production compared with the SmC system.     

Synthesis of a photoimmobilizable histidine polymer for surface modification

A novel photoreactive polymer with histidine polar groups was synthesized through the copolymerization of two types of methacrylic acid, one carrying histidine groups and the other carrying azidoaniline groups. The polymer was photoimmobilized on polyester disks for surface modification. The effect of the surface modification on the hydrophilic and biofouling properties was investigated. Static contact angle measurements showed that the polymeric surface was modified to be comparatively hydrophilic in the polymer‐immobilized region. Micropattern immobilization was carried out with a photolithographic method. Atomic force microscopy measurements showed that the polymer was formed on the disks in response to ultraviolet irradiation. Protein adsorption was reduced on the polymer‐immobilized regions, and in those regions, spreading and adhesion of mammalian cells were reduced in comparison with that in nonimmobilized regions. In conclusion, a novel histidine‐containing polymer was photoreactively immobilized on a conventional polymer surface, and it had reduced interaction with proteins and cells. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

New criteria for assessing local wind environment at pedestrian level based on exceedance probability analysis

In this present study, the wind environment was evaluated for local void domain at pedestrian level in the aspect of ventilation performance and thermal comfort. Exceedance probability analysis was applied as the main approach in order to estimate the uncertainties associated with the influence of climate on wind environment. Two criteria were proposed based on local air change rate and local kinetic energy respectively, which are domain-based indices allowing comprehensive estimation of local wind environment. Calculating output of these criteria in the form of cumulative distribution function forms a ground for reliability analysis of inadequate ventilation or thermal discomfort. A simple street canyon situated in Tokyo, defined as void model, was applied as an illustration of the new criteria in evaluating the local wind environment at ground level. The influences of two configuration factors: orientation and aspect ratio of the void model were investigated by CFD simulation. The results demonstrated that both factors show great influences on local ventilation performance, which also indicated the practicability and effectiveness of the proposed criteria to help achieving good wind environmental design.     

Solar cell efficiency tables (Version 31)

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since July, 2008 are reviewed. Copyright © 2007 John Wiley & Sons, Ltd.     

Application of the partial element equivalent circuit method to tower surge response calculations

This article presents calculations of tower surge responses and insulator voltages of an actual transmission tower including ground wires and phase wires. The partial element equivalent circuit (PEEC) method is applied as a simulation tool. Surge responses of the tower and insulator voltages calculated by the PEEC method are compared with electro magnetic transients program (EMTP) simulated results and experimental results collected from the literatures. The results calculated by the PEEC method agree well with the experimetal results, not only amplitudes but also waveshapes. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.