Illumination and scattered light detection using a light source consisting of sub-micrometer defect arrays formed on a extremely flat light waveguide core

We have previously argued that an optical sensor combined total analysis system (TAS) is one of the indispensable functional components needed to realize a “ubiquitous human healthcare” system. To achieve this goal, we have proposed a fundamental structure for illuminating a minute cell or particle running along a microfluidic channel using a flat waveguide construction. It is desirable that the TAS light source should be arranged as close to the specimen flow as possible in order to acquire the necessary optical properties; hence, artificial defects formed on the surface of a flat light waveguide are considered to be a promising candidate for realizing the arbitrary-shaped light source for a highly functional optical TAS structure. Based on this idea, we fabricated a structure, constructing a flat and square light source consisting of rectangular solids, sub-micrometer in size, with a 1-μm thick and a 12-μm wide light waveguide core. We successfully trial-manufactured an optical TAS chip with a fluidic channel containing a 14 × 10-μm cross section, and an extremely flat light waveguide core. We repeatedly confirmed that the defect array could function as an approximately square light source when a 650-nm wavelength laser power was carefully introduced. Furthermore, we developed a hybrid numerical calculation method base on the finite-difference, time-domain method together with the beam propagation method. Utilizing this hybrid method, we evaluated the optical response when a particle runs across the light source while changing the aperture length of a shading mask to obtain signals with both higher intensity and shorter full width at half maximum. The numerical results were compared with experimental results obtained using an image acquisition system, and demonstrated good qualitative accord.     

Flow regimes and vertical solids conveying in a spout‐fluid bed with a draft tube

Pressure fluctuation data were obtained in a semi‐cylindrical spout‐fluid bed with draft tube, and statistical analyses of them were employed to recognise flow regimes. Also, the effects of spouting‐gas and auxiliary‐gas velocities, and length of entrainment zone on solids loading ratio in a draft tube were examined. As a result, five flow regimes appeared by changing spouting‐gas and auxiliary‐gas velocities and it was found that the simplest method to determine flow regime is to measure pressure fluctuations in a draft tube. Moreover, solids loading ratio could be controlled flexibly by auxiliary‐gas velocity and length of entrainment zone.     

Development of a genetic transfer system in selenate-respiring bacterium Citrobacter sp. strain JSA which was isolated from natural freshwater sediment

Conjugative mating between the selenate-reducing bacterium Citrobacter sp. strain JSA and Escherichia coli S17-1 harboring the broad-host-range plasmid pKT230 or pKT240 (IncQ) allowed genetic transfer to strain JSA at a maximum frequency of 2.5×10(-5) (pKT230) and 5.1×10(-6) (pKT240) per recipient JSA cell. Kanamycin-resistant (selection marker of pKT230 and pKT240) transconjugants were routinely obtained with this method, and we confirmed that both vectors were also successfully transferred and replicated in strain JSA without alteration of the replicon. Furthermore, an electroporation method has also allowed transformation of JSA at a frequency of 10(-7) to 10(-6) transformants per μg vector DNA (per recipient cell), and PCR and hybridization analyses revealed that pKT230 and pKT240 are stably maintained in transformed JSA cells. These results indicated that both InQ plasmids can be used as vectors for gene transfer to selenate-reducing strain JSA. This is the first study to demonstrate an effective method for genetic transfer in a selenate-reducing Citrobacter bacterium and will aid in the elucidation of the selenium oxyanion reduction mechanism in this genus of environmental selenate-respiring isolates.     

Experimental investigation of discharge characteristics of a surface‐wave‐produced planar plasma

Experimental investigations of the discharge characteristics of planartype surfacewaveproduced plasmas (SWP) have been carried out. On this apparatus, the efficiency of microwave power absorption into the plasma depends strongly on the thickness of the dielectric window. Especially at a thickness of 12 mm, it has been found that more than 80% of microwave power is absorbed into the plasma. In order that the uniform power absorption is brought about effectively in a wide range of gas pressures, the dielectric waveguide that is placed above the dielectric window needs the air gap between them. These experimental results will enable us to improve the apparatus configuration to achieve better operational performances of surface wave plasmas. © 2001 Scripta Technica, Electr Eng Jpn, 138(3): 9–18, 2002     

Development of a distributed power outage scheduling system by using bee‐gent

The Power Outage Scheduling Problem is a distributed constraint satisfaction problem in which scattered local power stations have to make schedules that are consistent with one another. However, synchronous backtrack algorithms, a well‐known method for distributed constraint satisfaction problems, have difficulty handling rapid schedule adjustments and impartial assignment of power station schedules. Thus, we propose two kinds of heuristics: parallel assignment and multiple priority strategies. We also developed a distributed system for the power outage scheduling problem which makes use of the above heuristics in order to ensure efficiency. The system is based on Bee‐gent (Bonding and Encapsulation Enhancement aGENT framework) and consists of schedulers for each power station and mediation agents which have cloning and merging functions to support the implementation of the heuristics. The result of the experiment shows an improvement when handling rapid adjustment and impartiality issues and indicates that this improvement is provided with reasonable computational overhead. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 139(3): 62–72, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.1161     

Strength Development in Phosphate-Bonded Calcium Aluminate Cements

The chemical reaction at room temperature between calcium aluminate cement (CAC) and NH₄H₂PO₄-based fertilizer solution causes the formation of ammonium calcium pyrophosphate (AmCPP) as an amorphous cementitious phase. This phase was responsible for the development of strength in rapid-setting phosphate-bonded cement (PBC) specimens. Hydrothermal treatment of PBC at 200°C led to phase transformations of AmCPP and CAC into crystalline hydroxyapatite as the major phase and anorthite as the minor one. The moderate growth of these interlocked crystals in the interspaces of amorphous phases played an important role in creating a dense microstructure, thereby conferring a very high strength to the PBC. In contrast, an excessive crystal growth, which caused the formation of porous microstructure, resulted in a reduction in strength.     

Metalation states versus enzyme activities of Cu, Zn-superoxide dismutase probed by electrospray ionization mass spectrometry

Cu, Zn-superoxide dismutase (SOD-1), an enzyme that catalyzes the disproportionation reaction of superoxide to produce oxygen and hydrogen peroxide, thereby protecting cells from oxidative stress, is a homodimer that coordinates one copper and one zinc ion per monomer. Cu (2+) and Zn (2+) ions play important roles in enzyme activity and structural stability, respectively. In addition, dimer formation is also essential for fulfilling the function of SOD-1. We here report on the reconstitution and enzyme activities of several metalation states of SOD-1 (Cu 4-, Cu 3Zn-, and Cu 2Zn 2-homodimers). Each metalation state of the reconstituted SOD-1 could be unambiguously differentiated by electrospray ionization mass spectrometry, the metal ions of which had been completely replaced by 99 atom % (63)Cu and (68)Zn stable isotopes. It was found that (1) the Cu 4-dimer possessed 84% of the activity of the native enzyme, (2) the Cu-site resisted being coordinated with Zn (2+) ions while the Zn-site could be bound with Cu (2+) ions, and (3) the simultaneous addition of the Cu (2+) and Zn (2+) ions to generate a fully metalated form produced the multiply metalated SOD-1 (Cu 4-, Cu 3Zn-, and Cu 2Zn 2-dimers), which were clearly distinguishable from one another by the use of the stable isotopes, while the sequential addition of Zn (2+) followed by the Cu (2+) ion predominantly produced a Cu 2Zn 2-dimer comparable to the native enzyme.     

Residual stress measurement of Al/steel dissimilar friction stir weld

ABSTRACT

The dissimilar welds between aluminium (Al) alloy, A6061-T6, and stainless steel, type 304, were fabricated by a friction stir welding (FSW) technique. The FSW tool was offset to Al side and the probe was inserted only into Al plate. The softening occurred in Al side due to the heat input during FSW, while the hardness increased by the post-ageing treatment. Tensile strength of dissimilar weld also increased about 8.5% by the post-ageing. The residual stresses were measured based on the cos α method. The residual stresses parallel to the weld line, σ_xr, were predominantly tensile, while those perpendicular to the weld line, σ_yr, were compressive. Post-ageing treatment had little effect on the residual stresses.     

Effects of carbon source on denitrification efficiency and microbial community structure in a saline wastewater treatment process

Two different denitrifying reactors were monitored in order to evaluate the effects of carbon source on denitrification efficiency and microbial community structure under various saline conditions. Nitrogen removal performances were determined when salinity concentrations increase gradually in acetate- or methanol-fed denitrifying reactor. As a result, acetate-fed process attained high nitrate removal at 0-10% NaCl, while methanol was proven beneficial electron donors at 0-3% NaCl. A parallel analysis of T-RFLP and cloning in the acetate-fed sludge showed that a specialized microbial population (i.e. the genera Halomonas and Marinobacter) adapted to a high saline environment. Meanwhile, there were no major changes of bacterial populations in the methanol-fed reactor at 4% NaCl, although the relative abundances of the genera Azoarcus and Methylophaga increased when salinity concentration was at 1-3% NaCl, indicating that methanol-utilizing populations in activated sludge was unable to adapt to a high saline environments (>4% NaCl).     

Fermentation-induced changes in the concentrations of organic acids,amino acids,sugars, and minerals and superoxide dismutase-like activity in tomato vinegar

Various raw materials are used to produce vinegars that contain functional compounds associated with disease prevention. We evaluated changes in functional compounds during tomato vinegar production and superoxide dismutase-like activity of tomato vinegar. Tomato vinegar contained abundant anti-hypertensive compounds, e.g., γ-aminobutyric acid and potassium derived from tomatoes and acetic acid and pyroglutamic acid produced during fermentation. It had stronger superoxide dismutase-like activity than commercial vinegars because of tomato-derived superoxide dismutase-like compounds, including phenolic acids, flavonoids, and glutathione. These data indicate that tomato vinegar is a candidate dietary supplement with potential preventive effects against cardiovascular diseases due to its anti-hypertensive and superoxide dismutase-like compounds.