Microscopic and chemical study of anisotropic mesophase possessing novel features

Anisotropic mesophase possessing novel features obtained from acenaphthylene was studied by optical and scanning electron microscopy. Variations in refluxing temperature affected the shapes of resultant anisotropic mesophase, suggesting that growth mechanisms were influenced. Polarized-light microscopy at high magnification revealed several structural types indicating that the single mesophase unit contains two domains with quite different lamellar molecular orientations. The novel mesophase, isolated by quinoline extraction, was also examined microscopically. It possessed shapes similar to those observed in dendritic growth of some graphitic substances. The quinoline-soluble fraction associated with this novel mesophase is assumed to be a dehydrogenated linear polymer of acenaphthylene, whereas the soluble matter associated with usual mesophase spheres is assumed to be decacyclene as previously reported. The mechanism of formation of this novel mesophase during refluxing is discussed in these terms.     

Quantitative description and modification of cocarbonization compatibility of pitch fractions

The cocarbonization properties of the benzene-soluble fractions (BS) of several pitches with benzene-insoluble fractions (BI) of SRC pitches were studied, changing their mixing ratio in order to evaluate their compatibility for needle-coke formation; the smallest BS content required may reflect its cocarbonization ability to provide the carbonizing mixture with fusibility or suitable reactivity for this purpose. More than 90% of BS content was required for the BS—BI mixture of smallest compatibility, whereas only 10% was enough for the mixture of best compatibility. Ethylene tar BS of poor compatibility with solvent-refined-coal BI could be modified and improved for this purpose by catalytic reaction with aluminium chloride at 260 ° C, whereas ferric or cupric chloride failed. Based on the analytical study of BS and these results, the compatibility of pitch fractions is discussed from the viewpoint of pitch structure.     

High-performance poly-Si TFTs with ECR-plasma hydrogen passivation

High-performance thin-film transistors (TFTs) with electron-cyclotron resonance (ECR) plasma hydrogen passivation fabricated by the use of laser-recrystallized multiple-strip-structure poly-Si film are discussed. These TFTs have n-channel enhancement-mode characteristics with a large transconductance, a high switching ratio, and a threshold voltage as low as 0.4 v. The ECR-plasma hydrogen passivation of laser-recrystallized poly-Si, reduces the trap density of poly-Si and increases the carrier mobility thus, desirable TFT characteristics are obtained. This passivation increased the transconductance (g_m) of a TFT and decreased the leakage current between the source and the drain. As a result, a switching ratio as high as 2.5×10⁹ and very low leakage current of the order of 10¹⁴ A can be achieved by these high-performance TFTs     

Carbonization of aromatic hydrocarbons—III: Carbonization catalyzed by alkali metals

Carbonization of aromatic hydrocarbons catalyzed by alkali metals has been studied to determine what sort of cokes will be formed. Hydrocarbons studied in the present paper were in every case carbonized into isotropic carbons at high yields, regardless of the kind of alkali metals, starting materials, and the heating rate. The carbon obtained may be compared to the glassy carbon among various isotropic carbons in the sense of its crystallite size, surface area and specific gravity, but completely differed from the carbon obtained from the same source by the aid of AlCl₃. Comparing these two carbonization processes promoted by different catalysts, the isotropic nature of carbons obtained by alkali metals is assumed to be due to the extensive dehydrogenation of the intermediate accelerated by the catalyst. Carbonization in solvents have been also studied to observe the effect of complete complex formation on the properties of the carbon.     

Mechanism of carbonization of a semianthracite

The carbonization of a semi-anthracite which produced a domain texture of large isochromatic units was studied to elucidate the mechanism for this type of anisotropic development. The observation of a series of its carbonization residues at several temperatures indicated that the anisotropic domains appeared simultaneously and no stepwise growth was observable. However, its co-carbonization with decacyclene or A240 pitch followed the typical mesophase mechanism to give a flow or coarse-mozaic texture which was quite similar to that observed in the coke produced from its quinoline extract. In contrast, the residue after quinoline extraction retained on carbonization the same basic anisotropy as the coal. The structure of the original coal and the coke was studied by topological observation before and after quinoline and gasification etching. The results suggest that during carbonization the preordered structure of the semi-anthracite is slightly rearranged, with the aid of the quinoline-soluble matter, to become more highly ordered giving a domain texture which corresponds to the isochromatic anisotropic regions of its basic anisotropy.     

Performance of a high-resolution contact-type linear image sensorwith a-Si:H/a-SiC:H heterojunction photodiodes

A 400 DPI (dots-per-inch) contact-type linear image sensor with a scanning speed of 2 ms/line using amorphous silicon photodiodes and poly-Si thin-film transistor drivers has been developed. The characteristics of the heterojunction photodiodes are discussed, and the results of sensor performance tests are examined in terms of output signal uniformity, photoresponse lag, spectral response, gray scale, and the reliability of the 400 DPI image sensor     

Mass production of D-psicose from d-fructose by a continuous bioreactor system using immobilized D-tagatose 3-epimerase

An improved process for the mass production of D-psicose from D-fructose was developed. A D-fructose solution (60%, pH 7.0) was passed at 45 degrees C through a column filled with immobilized D-tagatose 3-epimerase (D-TE) which was produced using recombinant Escherichia coli, and 25% of the substrate was converted to D-psicose. After epimerization, the substrate, D-fructose, was removed by treatment with baker's yeast. The supernatant was concentrated to a syrup by evaporation under vacuum and D-psicose was crystallized with ethanol. Approximately 20 kg of pure crystal D-psicose was obtained in 60 d.     

A unique photofunction of YVO4:Bi3+,Eu3+ nanophosphor: Photoluminescent indication for photochemical decomposition of polyurethane

We have developed a transparent composite film consisting of YVO₄:Bi³⁺,Eu³⁺ nanophosphor and polyurethane resin which exhibits unique photophysicochemical behavior. The nanophosphor shows red photoluminescence through f–f transitions of Eu³⁺ under near-UV irradiation. The emission intensity drops to half of the initial value after continuous irradiation for 23 h. As shown by electron spin resonance spectroscopy, this decrease in the emission intensity is caused by the formation of V⁴⁺ defects. In addition, thermal analysis and Fourier transform infrared spectroscopy show that the amount of the organic species in the film decreases from 58 to 25 wt% after 23 h. These results indicate that the nanophosphor promotes photooxidative decomposition of the polyurethane resin, while some of the V⁵⁺ ions in YVO₄ are converted to V⁴⁺ ions by photoreduction. Prolonged irradiation for 96 h leads to complete decomposition of the polyurethane and the disappearance of the V⁴⁺ defects, resulting in the recovery of the emission intensity. These findings suggest that the photoluminescence of YVO₄:Bi³⁺,Eu³⁺ nanophosphor can be used to detect the photooxidative decomposition of polyurethane.     

Multiplex PCR for simultaneous detection of Salmonella spp., Listeria monocytogenes, and Escherichia coli O157:H7 in meat samples

A multiplex PCR method was developed for simultaneous detection of Salmonella spp., Listeria monocytogenes, and Escherichia coli O157:H7 in meat samples. DNA detection sensitivity for this method was 10(3) CFU/ml for each pathogen. When this protocol was used for the detection of each of the above pathogenic bacteria in spiked pork samples, 1 cell per 25 g of inoculated sample could be detected within 30 h. In the samples of naturally contaminated meat, Salmonella spp., L. monocytogenes, and E. coli O157:H7 were detected over the same time period. Excellent agreement was obtained for the results of multiplex PCR and the conventional culture method, which suggests that the multiplex PCR is a reliable and useful method for rapid screening of meat products for Salmonella spp., L. monocytogenes, and E. coli O157:H7 contamination.