The electrical properties of polymer nanocomposites with carbon nanotube fillers

The electrical properties of polymer nanocomposites containing a small amount of carbon nanotube (CNT) are remarkably superior to those of conventional electronic composites. Based on three-dimensional (3D) statistical percolation and 3D resistor network modeling, the electrical properties of CNT nanocomposites, at and after percolation, were successfully predicted in this work. The numerical analysis was also extended to investigate the effects of the aspect ratio, the electrical conductivity, the aggregation and the shape of CNTs on the electrical properties of the nanocomposites. A simple empirical model was also established based on present numerical simulations to predict the electrical conductivity in several electronic composites with various fillers. This investigation further highlighted the importance of theoretical and numerical analyses in the exploration of basic physical phenomena, such as percolation and conductivity in novel nanocomposites.     

Therapy of myeloma in vivo using marine phospholipid in combination with Agaricus blazei Murill as an immune respond activator

Mushroom (Agaricus blazei Murill) extract has been reported to possess antitumor effects through immune activation. Here, we investigated the beneficial effects of combining A. blazei extract with marine phospholipids in comparison to A. blazei extract alone on myeloma sp2 tumor suppression when orally administrated. The experimental groups designed for sp2 tumor bearing BALB/c nu/nu mice were drinks of: (1)control; (2)1.0 mg/mL squid phospholipid liposome alone; (3)0.5 mg/mL A. blazei Murill water extract alone; (4)1.0 mg/mL squid phospholipid liposome with 0.5 mg/mL A. blazei Murill water extract in the form of those simple mixture; and (5)1.0 mg/mL squid phospholipid liposome with 0.5 mg/mL A. blazei Murill water extract partially encapsulated. Orally administrated volumes amounted to approximately 5 mL per day per mouse for all groups. A. blazei Murill water extract alone and squid phospholipid alone served groups show moderate tumor suppression with total administrations of approximately 105 mg/mouse for squid phospholipid through out the experimental term. When both A. blazei Murill water extract and squid phospholipid were administrated simultaneously in a simple mixture form, promotional effect on cancer tumor suppression was observed. And when A. blazei Murill water extract was partially encapsulated in the squid phospholipid liposomes with total administrations being 105 mg/mouse for squid phospholipid, effect on cancer tumor suppression was more pronounced. Though there was no statistically significant difference in tumor sizes between the simple mixture form administrated group i.e. group (4) and the partially encapsulated form administrated group i.e. group (5), the tumor vanished mouse was seen in the partially encapsulated form administrated group. Thus it was concluded that combinational administration of the A. blazei Murill water extract and the marine phospholipid may be useful in myeloma sp2 therapy.     

Stabilization of entrapped catalase using photo‐crosslinked resin gel for use in wastewater containing hydrogen peroxide

Catalase immobilized using photo‐crosslinkable resin was applied to treatment of wastewater containing a low concentration of hydrogen peroxide. The structure of photo‐crosslinked resin gel was stable even in the acceleration test of concentrated hydrogen peroxide for a long period. Accordingly, the most important subject of this process was maintaining long term catalase activity. The stabilization of immobilized catalase was investigated by modifying gel carriers with some prepolymers and functional monomers, and adding some stabilizing materials without modification of catalase itself. But these gel carriers did not improve the stability beyond 20%. Addition of Tween 80, polyoxyethylene (5) sorbitan monooleate (hydrophilic/lipophilic balance, HLB: 10.0), to catalase was most effective for maintenance of the activity when the enzyme was immobilized in hydrophilic photo‐crosslinked resin, resulting in 80% of its initial activity. It was assumed that this surfactant did not influence the permeation of hydrogen peroxide into gel, but acted as a stabilizer for catalase in the gel carrier. © 2000 Society of Chemical Industry     

A Phylogenetic Analysis of Saccharomyces Species by the Sequence of 18S–28S rRNA Spacer Regions

Sequences of two internally transcribed spacer regions between 18S and 28S rRNA genes were determined to assess the phylogenetic relationship in the strains belonging to the genus Saccharomyces. The sequences of S. bayanus and S. pastorianus were quite similar, but not identical. Two phylogenetic trees constructed by the neighbor-joining method showed that all the species examined were distinguished from one another. The Saccharomyces sensu stricto species: S. cerevisiae, S. bayanus, S. paradoxus and S. pastorianus, were closely related and far from the Saccharomyces sensu lato species including S. barnetti, S. castellii, S. dairensis, S. exiguus, S. servazzii, S. spencerorum and S. unisporus, and an outlying species, S. kluyveri. © 1997 John Wiley & Sons, Ltd.     

Modification of bismaleimide resin by poly(propylene phthalate), poly(butylene phthalate) and related (co)polyesters

Aromatic polyesters were prepared and used to decrease the brittleness of the bismaleimide resin composed of 4,4′-bismaleimidediphenyl methane (BMI) and o,o′-diallyl bisphenol A (DBA) (Matrimid 5292 resin). The aromatic polyesters included poly(propylene phthalate) (PPP), poly(2,2-dimethylpropylene phthalate) (PDPP), poly(butylene phthalate) (PBP) and poly(butylene phthalate-co-butylene terephthalate) (50mol% terephthalate unit) (PBPT). The polyesters were effective modifiers for decreasing the brittleness of the bismaleimide resin. For example, inclusion of 20wt% PPP (MW 18700) led to 50% increase in the fracture toughness (K_IC) with retention of flexural properties and a slight loss of the glass transition temperature, compared with the mechanical and thermal properties of the unmodified cured bismaleimide resin. Micro-structures of the modified resins were examined by scanning electron microscopy and dynamic viscoelastic analysis. The thermal stability of the modified resins was slightly lower than that of the unmodified resin as determined by thermogravimetric analysis. The toughening mechanism is discussed in terms of the morphological and dynamic viscoelastic behaviour of the modified bismaleimide resin system. © 1998 SCI.     

A scheduling method considering register‐to‐register transfers

In high‐level synthesis, scheduling is an important stage which assigns each operation appearing in a data flow graph to a specific control step, whose results influence the design quality directly. This paper describes a scheduling approach for pipelined datapaths. Since few previous approaches estimate the interconnection cost between register (register‐to‐register cost), our approach introduces a datapath model with interconnection between registers across buses, and minimizes the total hardware cost including the register‐to‐register cost by force‐directed scheduling. © 1999 Scripta Technica, Electr Eng Jpn, 128(3): 63–71, 1999     

Novel repeated batch operation for flash fermentation system: Experimental data and mathematical modelling

A novel repeated batch operation mode was proposed for ethanol fermentation, where the fermenter beer was periodically exchanged between the fermenter with biomass recycle and the distillation unit, to promote the selective removal of ethanol. Using the mathematical model developed, as based on the experimental results, the optimal operation of the proposed method was shown to attain high performance, with a productivity of about 12 g dm⁻³ h⁻¹ and a product concentration of 400 g dm⁻³.     

Steroid hormone profiles of urban and tidal rivers using LC/MS/MS equipped with electrospray ionization and atmospheric pressure photoionization sources

A highly sensitive and uncomplicated method of analyzing steroidal hormones in river and estuarine water samples was developed using a liquid chromatography tandem mass spectrometer equipped with an electrospray ionization (ESI) source and atmospheric pressure photoionization (APPI) source. Steroidal hormones included not only estrogen but also androgen and conjugates of these two. APPI displayed greater sensitivity than ESI for most of the unconjugated steroids examined, with very high sensitivity for testosterone and 4-androstene-3,17-dione in particular. For conjugated hormones, in contrast, ESI was more effective. The method developed was applied to the determination of hormones in the rivers of Osaka City and their estuaries, where the hormones detected were affected by the effluent from municipal wastewater treatment plants (WWTPs), and hormone concentration values were comparable to those reported in previous studies of such effluent. Because of the two-way flow and stagnancy of streams and watercourses, continuous input of steroidal hormones from WWTPs seems to bring about local accumulation. Levels of androgen were 1 order of magnitude lower than those of estrogen. Estrone, estrone 3-sulfate, and 4-androstene-3,17-dione were detected in almost all water samples, with maxima of 51, 5.1, and 6.4 ng L(-1), respectively.