A differential mobility analyzer and a Faraday cup electrometer for operation at 200–930 Pa pressure

We have developed a differential mobility analyzer (DMA) based on the DMA devised by Seto et al. (1997) and a Faraday cup electrometer for measurement of nanometer-sized particles at a few hundred Pa and examined the operating characteristics of the DMA using the tandem DMA technique. The tandem DMA calibration establishes that the DMA successfully classifies particles in the 200–930 Pa pressure range. It was also found that the transfer function of the DMA follows the triangular transfer function and the resolution of the DMA is close to that given for an ideal case. As a standard of a minimum pressure that may be probed with the present DMA system, 400 Pa is estimated when the DMA operates with a 3 nlmin⁻¹ sheath flow and a 1 nlmin⁻¹ aerosol flow rate.     

Fatigue behaviour of dissimilar friction stir welds between wrought and cast aluminium alloys

Wrought aluminium alloy, A6016-T4, was welded to cast one ADC12 by a friction stir welding technique. A6016 was set on the advancing side, while ADC12 was on the retreating side based on the pre-tensile test results. The dissimilar welds exhibited lower fatigue strengths than A6016 but higher than that of ADC12. Fatigue strengths increased when the tool was offset into ADC12, which could be explained based on the risk volume concept. When ADC12 was set on the advancing side, the fatigue strengths decreased. Microstructural observation revealed that the macroscopic structure in the stir zone drastically changed by putting ADC12 on the advancing side, and insufficient mixing of dissimilar alloys resulted in the lower fatigue strengths.     

Identification of Sperm-Binding Sites in the N-Terminal Domain of Bovine Egg Coat Glycoprotein ZP4

The species-selective interaction between sperm and egg at the beginning of mammalian fertilisation is partly mediated by a transparent envelope called the zona pellucida (ZP). The ZP is composed of three or four glycoproteins (ZP1–ZP4). The functions of the three proteins present in mice (ZP1–ZP3) have been extensively studied. However, the biological role of ZP4, which was found in all other mammals studied so far, has remained largely unknown. Previously, by developing a solid support assay system, we showed that ZP4 exhibits sperm-binding activity in bovines and the N-terminal domain of bovine ZP4 (bZP4 ZP-N1 domain) is a sperm-binding region. Here, we show that bovine sperm bind to the bZP4 ZP-N1 domain in a species-selective manner and that N-glycosylation is not required for sperm-binding activity. Moreover, we identified three sites involved in sperm binding (site I: from Gln-41 to Pro-46, site II: from Leu-65 to Ser-68 and site III: from Thr-108 to Ile-123) in the bZP4 ZP-N1 domain using chimeric bovine/porcine and bovine/human ZP4 recombinant proteins. These results provide in vitro experimental evidence for the role of the bZP4 ZP-N1 domain in mediating sperm binding to the ZP.     

Preparation of Linear π-Conjugated Coordination Polymers Having Ruthenium(II) Complex in the Main Chain

Soluble -conjugated coordination polymers having a ruthenium(II) complex in the main chain were prepared from a soluble metal complex monomer and a bridging ligand via coordination. Refluxing of an ethanol-water suspension containing (4,4-dinonyl-2,2-bipyridyl)Ru(III) with 2,3-bis(2-pyridyl)pyrazine gave the coordination polymer. The resulting polymer was soluble in common organic solvents. The structure was confirmed by uv/vis spectra and gpc analysis.     

Synthesis of hydroboration copolymer of TCNQ and formation of polymer charge transfer complex therefrom

Summary Novel TCNQ copolymers were prepared by hydroboration copolymerization of TCNQ with mesitylborane. The polymers obtained exhibited characteristics as a new class of polymer electron acceptors. When these polymers were treated with p-phenylenediamine at 80°C – 140°C in diglyme solutions, charge transfer complex formation was observed in UV-vis spectra. Hydroboration polymerization of p-, m-dicyanotetrafluorobenzene also proceeded to give the corresponding polymer electron acceptors. Received: 29 September 1998/Revised version: 17 November 1998/Accepted: 24 November 1998     

Roles of catalytic residues in {alpha}-amylases as evidenced by the structures of the product-complexed mutants of a maltotetraose-forming amylase

The crystal structures of the four product-complexed singlemutants of the catalytic residues of Pseudomonas stutzeri maltotetraose-forming-amylase, E219G, D193N, D193G and D294N, have been determined.Possible roles of the catalytic residues Glu219, Asp193 andAsp294 have been discussed by comparing the structures amongthe previously determined complexed mutant E219Q and the presentmutant enzymes. The results suggested that Asp193 predominantlyworks as the base catalyst (nucleophile), whose side chain atomlies in close proximity to the C1-atom of Glc4, being involvedin the intermediate formation in the hydrolysis reaction. WhileAsp294 works for tightly binding the substrate to give a twistedand a deformed conformation of the glucose ring at position–1 (Glc4). The hydrogen bond between the side chain atomof Glu219 and the O1-atom of Glc4, that implies the possibilityof interaction via hydrogen, consistently present throughoutthese analyses, supports the generally accepted role of thisresidue as the acid catalyst (proton donor).     

Shop floor control in computer-integrated manufacturing for large-scale integrated wafer fabrication systems

Manufacturing technology in the field of Large-Scale-Integrated (LSI) circuit production has overcome the problems of enlarged wafer size and increasing level of integration. The market environment of the LSI industry has become more demanding with increased requirements, delivery time and stiffer cost competition. A Computer-Integrated Manufacturing System (CIMS) well-adapted to the unique characteristics of LSI production system is thus urgently needed.

This paper describes the development of CIMS in LSI production systems, and presents the example of a DTS (Diffusion Total System), constructed in a real LSI wafer fabrication factory. Features of DTS are (a) on-line real-time manufacturing data acquisition and monitoring through a production information network, (b) automatic control of process equipment, (c) shop floor control for computer aided decision support at the shop floor level, and (d) data analysis and reporting derived from a large amount of accumulated data. This paper deals with shop floor control, and in particular with a priority control system unique to the LSI wafer fabrication line.     

Radiochemical synthesis of silver nanoparticles onto textile fabrics and their antibacterial activity

This paper presents a new technique for synthesizing silver nanoparticles immobilized on textile fabrics using a radiochemical process. In this process, the irradiation of a high-energy electron beam on an aqueous solution containing silver ions induces a reducing reaction that forms metallic silver nanoparticles. Small Ag particles of about 2–4 nm were observed together with relatively large particles of more than 10 nm. These nanoparticles are firmly immobilized on the surface of a support textile fabric without the need for any binder or surfactant. The amount of silver nanoparticles immobilized was found to depend on the water content of the support textile fabric, suggesting that the silver ions are reduced not only by radiochemical species generated by the radiolysis of water, but also by radiochemical species generated in the irradiated support fabric itself. The silver nanoparticles that were immobilized on the support textile fabric exhibited an excellent antibacterial activity across a wide antibacterial spectrum, even after a durability test involving washing the fabric 100 times.     

EFFECT OF IRON CATALYST ON THE COMPOSITION OF OIL FROM COAL LIQUEFACTION

The effect of two iron catalysts, red mud and CGS S-G, as well as C0-Mo/AI₂O3 and Ni-Mo/Al₂03 commercial catalysts on the composition of oil derived from the liquefaction of Japanese subbituminous coal have been investigated comparatively by conventional autoclave experiments at 440 and 450^°C under initial hydrogen pressure of 85kg/cm² G with tetralin to coal weight ratio of 3. From the results obtained at 450^°C, total conversion and the yield of gas revealed almost same level with four catalysts, but the oil product from molybdenum catalysts showed higher yield than that from iron catalysts. CGS S-G catalyst also showed higher yield of oil product than red mud catalyst. Reaction behavior of two iron catalysts were also tested by solvent recycle mode experiments.     

Possible Immune Regulation of Natural Killer T Cells in a Murine Model of Metal Ion-Induced Allergic Contact Dermatitis

Metal often causes delayed-type hypersensitivity reactions, which are possibly mediated by accumulating T cells in the inflamed skin, called irritant or allergic contact dermatitis. However, accumulating T cells during development of a metal allergy are poorly characterized because a suitable animal model is unavailable. We have previously established novel murine models of metal allergy and found accumulation of both metal-specific T cells and natural killer (NK) T cells in the inflamed skin. In our novel models of metal allergy, skin hypersensitivity responses were induced through repeated sensitizations by administration of metal chloride and lipopolysaccharide into the mouse groin followed by metal chloride challenge in the footpad. These models enabled us to investigate the precise mechanisms of the immune responses of metal allergy in the inflamed skin. In this review, we summarize the immune responses in several murine models of metal allergy and describe which antigen-specific responses occur in the inflamed skin during allergic contact dermatitis in terms of the T cell receptor. In addition, we consider the immune regulation of accumulated NK T cells in metal ion–induced allergic contact dermatitis.