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.     

Atrazine sensor based on molecularly imprinted polymer-modified gold electrode

Molecularly imprinted polymers (MIP) have been elucidated to work as artificial receptors. In our present study, a MIP was applied as a molecular recognition element to a chemical sensor. We have constructed an atrazine sensor based on a MIP layer selective for atrazine and its electrochemical reduction on gold electrode. The atrazine sensor was fabricated by directly polymerizing the atrazine-imprinted polymer composed from methacrylic acid and ethylene glycol dimethacrylate onto the surface of a gold electrode. By introducing LiCl into the MIP, atrazine was reduced below -800 mV vs Ag/AgCl reference electrode, at pH 3. The cathodic current of atrazine depended on the concentration of atrazine at the range of 1-10 microM. The sensor exhibited a selective response to atrazine. A nonimprinted polymer-modified electrode did not show selective response to atrazine, thus implying that the imprinted polymer acts as recognition element of atrazine sensor.     

Minute particle detection using a light-wave-guide incorporated optical total analysis system

An optical sensor combined total analysis system (TAS) is thought to be one of the most effective functional elements in realizing a ubiquitous human healthcare system. In accordance with this concept, we have proposed a fundamental structure of a light-wave-guide incorporated TAS and have developed a micro fluidic channel fabricated chip, where two light waveguides having approximately 10-??m cores were facing each other across a fluidic channel with a width of 12???m. By passing 5-??m-diameter polystyrene particles across the portion where a light-wave-guide and the fluidic channel intersect at a right angles, we confirmed that changes to transmitted light and scattered light were detectable even with an extremely low laser source power of 5???W, and they increased proportionally as the introduced laser power became higher. Increasing the introduced laser power clearly increased the correlation between the transmitted and scattered light change. Here we discuss in detail the two different correlation tendencies that appeared in the correlation maps.     

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.     

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.     

Effect of side chain structure on aggregation state and mechanical properties of synthetic polypeptide monolayers at the air-water interface

Synopsis Aggregation structure of poly(γ-methyl-L-glutamate)(PMLG) and poly(γ-n-hexyl-L-glutamate)(PnHLG) monolayers at the air-water interface was investigated on the basis of the transmission electron microscopic observation. The bright field image of PMLG and PnHLG monolayers exhibited a homogeneous structure at surface pressure of 18 mN·m⁻¹ and 15 mN·m⁻¹, respectively. The bright field image of PMLG monolayers showed linear humps at high surface pressure, suggesting the collapse of monolayers and the orientation of α-helix axis perpendicular to the compression direction. Surface pressure anisotropy was investigated by means of orthogonal Wilhelmy plate method. The surface pressure anisotropy for PMLG was greater than that for PnHLG. Dynamic viscoelastic properties of polypeptides monolayers at the air-water interface were examined on the basis of transient response of surface pressure. The magnitude of dynamic storage modulus E' of the PnHLG monolayer was lower than that of PMLG monolayer. This is ascribed to the active side chain motion of PnHLG at room temperature. The mechanical properties and aggregation structure of polypeptide monolayers were revealed to depend on their thermal molecular motion of side chain.     

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     

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.     

Effects of substrate surface finish and substrate material on durability of thermally sprayed WC cermet coating in rolling with sliding contact

In this study, using a two-roller testing machine, the authors examined the surface durability of thermally sprayed WC-Cr-Ni cermet coating in lubricated rolling with sliding contact conditions. The coating was formed onto the axially ground, blasted and circumferentially ground roller specimens made of a thermally refined carbon steel or an induction hardened carbon steel by means of the high energy type flame spraying (Hi-HVOF) method. The WC cermet coated roller finished to a mirror-like condition was mated with the carburized steel roller without coating having a surface roughness of Ry=3.05.0 μm. In the experiments, a maximum Hertzian stress of P_H=0.6 or 0.8 GPa was applied for the thermally refined carbon steel roller and P_H=1.4 GPa was applied for the induction hardened carbon steel roller in line contact condition. As a result, it was found that in the case of induction hardened steel substrate, the coated roller generally exhibits a long life without any serious damage and the surface durability is hardly affected by the substrate surface finish, while in the case of thermally refined steel substrate, the durability of coated roller is lowered and the life to flaking is very short particularly when the substrate surface is circumferentially ground and the mating surface is rough. The surface durability of coated roller was also compared with the durability of steel roller without coating. Finally, in order to discuss the durability of coated roller, the elastic-plastic behavior of the subsurface layer under repeated rolling with sliding contact was analyzed using a finite element method (FEM).