Reaction mechanism of coal hydrogenation: 2. Three rings solvent system

Taiheiyo coal was hydrogenated in phenanthrene, 9,10-dihydrophenanthrene, 1,2,3,4,5,6,7,8-octahydrophenanthrene and perhydrophenanthrene under 10 MPa (initial pressure) of hydrogen or nitrogen with or without stabilized nickel as catalyst at 400 °C for 15 min. Preasphaltene, asphaltene and oil conversions and the conversion of solvents were measured, and the amounts of hydrogen absorbed by coal from molecular hydrogen and from donor solvent were calculated. The main route of reaction appears to be the direct hydrogenation of coal by molecular hydrogen and the contribution of hydrogenation via the solvent was greater than in the case of the two rings solvent system.     

Vinyl polymerization: 414. Polymerization of vinyl monomer initiated by poly(N,N,N-trimethyl-N-2-methacryloxyethyl)ammonium chloride

The polymerization of vinyl monomer initiated by an aqueous solution of poly(N,N,N-trimethyl-N-2-methacryloxyethyl)ammonium chloride (poly(Q-DMAEM-CI) has been carried out at 85°C. The effects of the amounts of vinyl monomer, poly(Q-DMAEM-CI) and water on the conversion of vinyl monomer have been studied. The overall activation energy in the polymerization of MMA is estimated as 41.9 kJ mol^?1. The polymerization proceeds through a radical mechanism. The location in which the polymerization occurs is discussed. The selectivity for vinyl monomer is explained by ‘the concept of hard and soft hydrophobic areas and monomers’.     

Coking reaction in hydrogenation

Asphaltene prepared from a Japanese coal (Akabira, 81.2 wt% C) and coal tar pitch were heat treated under nitrogen or hydrogen. Under nitrogen the initial thermal decomposition produced radicals which abstracted hydrogen from other molecules to stabilize and to produce smaller molecules and gas. The molecules from which hydrogen was abstracted as well as other radicals polycondensed to produce heavier solvent-insoluble fractions. Under hydrogen the radicals were stabilized by hydrogen gas to produce smaller molecules avoiding the production of a heavier fraction. The higher the hydrogen pressure, the smaller was the yield of heavier fraction and the larger the yield of lighter fraction. Higher temperature accelerated the production of the heavier fraction. Donor solvents could reduce the production of the heavier fraction.     

Pressure and temperature effects on the hydrogenation of coal-derived asphaltene

Pressure and temperature effects on hydrogenation reactions were examined using coal-derived asphaltene at 390,420 and 450 °C, under 3 and 10 MPa of hydrogen partial pressure. Higher conversion was obtained at higher reaction temperatures. Benzene-insoluble material (Bl) was formed at higher temperatures especially at low hydrogen pressure, this Bl being one-third of the reaction product at 450 °C. From structural analysis of unreacted asphaltenes and product oils, at 390 °C, it was concluded that smaller molecular components convert to oil initially and the larger molecules remain as unreacted asphaltene. Under higher hydrogen pressure for all temperatures carbon aromaticity (f_a) and number of aromatic ring per structural unit (R_aus) in unreacted asphaltenes were lower than those under lower hydrogen pressure suggesting that hydrogenation of the aromatic nucleus was promoted by higher pressure. At lower hydrogen pressure, R_aus for asphaltenes at higher temperature is larger than that at lower temperature. This suggests that at lower hydrogen pressure, dehydrogenation or condensation reactions occur more easily. A large effect at higher hydrogen pressure was a reduction in the extent of condensation reactions. Higher reaction temperatures contribute to splitting of bridged linkages so reducing molecular size and degree of aromatization.     

In Vivo Probing of the Temperature Responses of Intracellular Biomolecules in Yeast Cells by Label‐Free Raman Microspectroscopy

Environmental temperature is an essential physical quantity that substantially influences cell physiology by changing the equilibria and kinetics of biochemical reactions occurring in cells. Although it has been extensively used as a readily controllable parameter in genetic and biochemical research, much remains to be explored about the temperature responses of intracellular biomolecules in vivo and at the molecular level. Here we report in vivo probing, achieved with label‐free Raman microspectroscopy, of the temperature responses of major intracellular components such as lipids and proteins in living fission yeast cells. The characteristic Raman band at 1602 cm^?1, which has been attributed mainly to ergosterol, showed a significant decrease (≈47 %) in intensity at elevated temperatures above 35 °C. In contrast to this high temperature sensitivity of the ergosterol Raman band, the phospholipid and protein Raman bands did not vary much with increasing culture temperature in the 26–38 °C range. This finding agrees with a previous biochemical study that showed that the initial stages of ergosterol biosynthesis in yeast are hindered by temperature elevation. Moreover, our result demonstrates that Raman microspectroscopy holds promise for elucidation of temperature‐dependent cellular activities in living cells, with a high molecular specificity that the commonly used fluorescence microscopy cannot offer.     

Motility and the expression of the flagellin protein FliC are negatively regulated by quorum sensing in Edwardsiella tarda

Edwardsiella tarda is a gram-negative bacterial pathogen of fish and animals. A number of gram-negative bacteria have quorum-sensing systems and produce N-acylhomoserine lactone (AHL) that they use as a quorum-sensing signaling molecule. We have already reported that E. tarda NUF251 produces AHLs and has the AHL-synthase gene, edwI. Inactivation of NUF251 edwI induces expression of an approximately 45 kDa extracellular protein, identified as a flagellin encoded by FliC. Mutation of edwI also changes the motility pattern of NUF251 from a radial expansion pattern to concentric rings. The addition of exogenous AHL was capable of restoring normal motility to NUF251 edwI mutants. These results demonstrate that quorum sensing negatively regulates motility and expression of the FliC protein.     

An efficient construction and application usefulness of rectangle greedy covers

We develop efficient construction methods of a rectangle greedy cover (RGC), and evaluate its usefulness in applications. An RGC is a greedy cover of the set of given positive instances by exclusive axis-parallel hyperrectangles, namely, axis-parallel hyperrectangles that exclude all the given negative instances. An RGC is expected to be a compact classification rule with high readability because the number of its component rectangles is expected to be small and it can be seen as a disjunctive normal form, which is one of the most readable representations for us.     

A PEG-based biocompatible block catiomer with high buffering capacity for the construction of polyplex micelles showing efficient gene transfer toward primary cells

Nonviral gene vectors from synthetic catiomers (polyplexes) are a promising alternative to viral vectors. In particular, many recent efforts have been devoted to the construction of biocompatible polyplexes for in vivo nonviral gene therapy. A promising approach in this regard is the use of poly(ethylene glycol) (PEG)-based block catiomers, which form a nanoscaled core-shell polyplex with biocompatible PEG palisades. In this study, a series of PEG-based block catiomers with different amine functionalities were newly prepared by a simple and affordable synthetic procedure based on an aminolysis reaction, and their utility as gene carriers was investigated. This study revealed that the block catiomers carrying the ethylenediamine unit at the side chain are capable of efficient and less toxic transfection even toward primary cells, highlighting critical structural factors of the cationic units in the construction of polyplex-type gene vectors. Moreover, the availability of the polyplex micelle for transfection with primary osteoblasts will facilitate its use for bone regeneration in vivo mediated by nonviral gene transfection.     

Low-base-resistance InP/InGaAs heterojunction bipolar transistors with a compositionally graded-base structure

To reduce base resistance of an InP/InGaAs heterojunction bipolar transistor grown by gas-source molecular beam epitaxy, the doping characteristics of carbon-doped InGaAs and the dependence of doping concentration on current gain were investigated. Using a thicker graded base was found to increase current gain significantly, resulting in increased doping level in the InGaAs: C-base layer. In particular, an 80-nm-thick graded base produces a base sheet resistance of 285 Ω/sq and maintains a practically useful current gain of 23 and a high cut-off frequency of 139 GHz.     

High‐frequency voltage oscillation in transformer windings and electrical breakdown properties of interturn insulation immersed in oil at VFT voltage

Switching operations in gas insulated switchgear (GIS) can generate very fast transient overvoltages (VFTO) which propagate in the GIS with little attenuation. When a transformer is directly connected to the GIS through a gas/oil bushing, the VFTO can enter the transformer and excite the voltage oscillation in the windings. In the paper, we firstly show a resonance phenomenon due to the superposition of the traveling waves which was found in the experiments using the coil windings of a 500 kV transformer. The fundamental resonance frequency ranged at about 2 MHz, and its voltage at the interturn (turn‐to‐turn) of the coil could reach 0.25 times of the applied voltage in the worst case. Secondly, the electrical breakdown properties of interturn insulation in oil were studied, applying the unipolar and bipolar voltages with 2 MHz oscillatory frequency. The breakdown voltages at the unipolar and bipolar VFT oscillatory stresses were about 1.25 and 1.40 times higher than that at the standard lighting impulse, respectively. We discuss the experimental breakdown stresses with the ones estimated from the analysis of VFTO in the transformer windings and also show the methods to cope with the VFTO. © 2000 Scripta Technica, Electr Eng Jpn, 132(4): 45–52, 2000