Satoshi Makishima

Development of continuous flow type hydrothermal reactor for hemicellulose fraction recovery from corncob.

The semi-pilot scale of continuous flow type hydrothermal reactor has been investigated to separate hemicellulose fraction from corncob. We obtained the effective recovery of hemicellulose using tubular type reactor at 200 degrees C for 10 min. From constituent sugar analysis of corncob, 82.2% of xylan fraction was recovered as mixture of xylose, xylooligosaccharides and higher-xylooligosaccharide which has more than DP 10. During purification of solubilized fraction by hydrothermal reaction such as ultrafiltration and ion exchange resin, higher-xylooligosaccharide was recovered as the precipitate. This precipitate was identified as non-blanched xylan fraction which has from DP 11 to DP 21 mainly. In this system, only a small amount of furfural has been generated. This tubular reactor has a characteristic controllability of thermal history, and seems to be effective for sugar recovery from soft biomass like corncob.

New technology for medium voltage solid insulated switchgear

This paper describes epoxy casting, insulation and operating mechanism technologies applied to newly developed solid insulated switchgear (SIS). The main insulating material is epoxy resin of high toughness and high thermal-resistance. This resin increases mechanical and electrical strength, and enables the vacuum interrupter to be cast directly. Since movable parts of a vacuum circuit breaker and a vacuum disconnecting switch can not be insulated with solid insulation, composite insulation is applied to these part. This composition enables the insulating distance at atmospheric pressure in air to be decreased. For the operation mechanism, we developed a balanced magnetic actuator (BMA) with a permanent magnet and a solenoid coil. The BMA has characteristics such as low operating current, fewer parts and high reliability. With these new technologies, we have developed enclosed solid insulated switchgear of medium voltage class without SF/sub 6/ gas.

Material and simulation technology for solid insulated switchgear

We have developed solid insulated switchgear(SIS), which is designed for SF/sub 6/-free innovative medium voltage applications. A new epoxy casting material is applied, which contains a great deal of spherical silica to reduce viscosity and increase mechanical strength. This material has the high glass transition temperature, which provides high thermal resistance and also high toughness for directly molding the vacuum interrupter. The switchgear consists of some complicated casting insulators such as bushings and cable heads. These insulators are manufactured by the high-cycle automatic pressure gelation method. The flow and cure analysis of the casting material visualizes the curing process inside the molds and suggests the best manufacturing conditions such as temperature, speed and time.

Improvement in the productivity of xylooligosaccharides from waste medium after mushroom cultivation by hydrothermal treatment with suitable pretreatment

The effective xylooligosaccharides (XOs) production from the waste medium after mushroom cultivation (WM) was investigated. The WM contains rich nutrients (protein, etc.) which induce Maillard reaction with reducing sugars under hydrothermal conditions. To improve the productivity of XOs, the suitable pretreatment combined with washing and grinding was investigated, and subsequently hydrothermal treatment was demonstrated with batch type and continuous flow type reactor. The washing pretreatment with hot water of 60 degrees C was effective to remove nutrients from the WM, and it led to prevent brownish discoloration on the hydrothermal treatment. On the basis of experimental data, industrial XOs production processes consisting of the pretreatment, hydrothermal treatment and purification step was designed. During the designed process, 2.3 kg-dry of the purified XOs was produced from 30 kg-wet of the WM (15% yield as dry basis weight). Theoretical yield of XOs attained to 48% as xylan weight in the WM.

Dielectric property of curing epoxy resin and application for casting processes

Epoxy casting resin is used in heavy apparatus as insulation and structural material. To optimize epoxy casting processes, several analytic techniques are used. Different from other techniques, dielectric analysis (DEA) has the advantage of nondestructive and on-line process measurement. We tried to evaluate the cure profile of bis-phenol A type liquid epoxy casting resin with DEA, DSC and a viscometer simultaneously, and found that the ionic conduction portions of the loss factor correlated well with glass transition temperature and viscosity.

Structural characterization of hemicellulose released from corn cob in continuous flow type hydrothermal reactor

Hydrothermal reaction is known to be one of the most efficient procedures to extract hemicelluloses from lignocellulosic biomass. We investigated the molecular structure of xylooligosaccharides released from corn cob in a continuous flow type hydrothermal reactor designed in our group. The fraction precipitable from the extract with four volumes of ethanol was examined by 1H-NMR spectroscopy and MALDI-TOF MS before and after enzymatic treatment with different purified enzymes. The released water-soluble hemicellulose was found to correspond to a mixture of wide degree of polymerization range of acetylarabinoglucuronoxylan fragments (further as corn cob xylan abbreviated CX). Analysis of enzymatic hydrolyzates of CX with an acetylxylan esterase, GH3 β-xylosidase, GH10 and GH11 xylanases revealed that the main chain contains unsubstituted regions mixed with regions of xylopyranosyl residues partially acetylated and occasionally substituted by 4-O-methyl-d-glucuronic acid and arabinofuranose esterified with ferulic or coumaric acid. Single 2- and 3-O-acetylation was accompanied by 2,3-di-O-acetylation and 3-O-acetylation of Xylp residues substituted with MeGlcA. Most of the non-esterified arabinofuranose side residues were lost during the hydrodynamic process. Despite reduced branching, the acetylation and ferulic acid modification of pentose residues contribute to high yields and high solubility of the extracted CX. It is also shown that different enzyme treatments of CX may lead to various types of xylooligosaccharides of different biomedical potential.