Narrow-beam and power-penalty-free 1.3-/spl mu/m laser diodes with monolithically integrated waveguide lens formed by selective-area epitaxial growth

A narrow-beam has been realized in a 1.3 /spl mu/m Fabry-Perot laser diode monolithically integrated with a tapered waveguide lens. The beam divergences in the perpendicular and horizontal directions are reduced down to 12/spl deg/ and 11/spl deg/ by a selective area epitaxial growth technique. The threshold current has been kept as low as 14 mA comparable to the conventional ones. Neither kinks in the L-I curves nor changes of far-field patterns are observed in the wide temperature range from -40 to 80/spl deg/C. Furthermore, high cut-off frequency over 4 GHz and power penalty-free characteristic under 622 Mb/s-50 km transmission have been confirmed.     

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 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).     

What is a surrogate marker for optimal dialysis?

To find a surrogate marker to obtain optimal dialysis delivery from the viewpoint of nutrition, 180 maintenance hemodialysis patients (109 males/71 females) were enrolled between October 1999 and June 2006 at our kidney center. In the 449 hemodialysis treatments, ultrapure dialysis solutions and high-flux synthetic membranes were utilized. Parameters were measured by Kt/V(urea) and postdialysis urea rebound, Kc (the cellular membrane clearance for urea), urea clear space (CS), %creatinine generation rate, %lean body mass, total body water, and so on. We examined the correlation between dialysis delivery and nutritional parameters: Kt/V(urea) and postdialysis urea rebound were found to be strongly and negatively correlated with nutritional parameters. However, Kc and CS have shown positive and strong correlations with nutritional parameters such as %creatinine generation rate, %lean body mass, and total body water as well. In addition, the age factor was correlated with Kt/V(urea) positively, and it influenced Kc and CS negatively. As a conventional dialysis parameter, Kt/V(urea) did not reflect nutrition, but Kc was found to improve nutrition due to the increase of the dialysis delivery. Therefore, Kc might be a reliable surrogate marker for optimal dialysis.     

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.     

Protective effect of lutein after ischemia-reperfusion in the small intestine

Lutein is a carotenoid mainly found in green leafy vegetables and is located in the macula lutea in the human eye. Since humans cannot synthesise lutein de novo, it must be digested as food. The physiological importance of an orally administered compound depends on its interaction with target tissues. There is little information about the effects of intake of lutein in tissues other than the eyes. The aim of this study was to clarify the protective effect of lutein against oxidative injury using ischemia-reperfusion (I/R) model rats and to determine the relationship between pharmacokinetics and antioxidant activity of lutein. Intestinal I/R was induced by 30-min occlusion of the superior mesenteric artery followed by 60-min reperfusion. After 60 min of reperfusion, intestinal tissue was used for analysis of Evans blue dye extravasation, lipid peroxidation and myeloperoxidase activity. Lutein administered before I/R had a significant protective effect against oxidative injury.     

Effective cell separation utilizing poly(N-isopropylacrylamide)-grafted polypropylene membrane containing adsorbed antibody

We previously developed a cell separation method using a poly(N-isopropylacrylamide)-grafted polypropylene (PNIPAAm-g-PP) membrane containing an adsorbed monoclonal antibody (mAb). The purpose of this study is to elucidate the cell separation mechanism in detail and to design an optimal method. As the grafting yield of PNIPAAm increased, the level of the adsorption of IgG(1) and cell adhesion to the membrane decreased. After BSA was adsorbed to a PNIPAAm-g-PP membrane at 6 degrees C, where PNIPAAm was hydrophilic, a small amount of IgG(1) was adsorbed to the membrane at 37 degrees C, where PNIPAAm was hydrophobic. The desorption of the adsorbed IgG(1) was not enhanced even though temperature was reduced to 10 degrees C, where PNIPAAm was hydrophilic. These results indicate that the antibody adsorbed to the intact PP surface of the membrane predominantly contributes to the capture of target cells through the antigen-antibody reaction and that a thermoresponsive transition of PNIPAAm contributes to the detachment of the captured cells. The total number of cells recovered from a PNIPAAm-g-PP membrane containing the adsorbed mAb decreased as the grafting yield increased. A PNIPAAm-g-PP membrane with a 1.7% grafting yield containing adsorbed anti-human CD34 mAb enriched CD34-positive KG-1a cells to 85% from a 1:1 cell suspension of KG-1a cells and CD34-negative Jurkat cells.     

Hydrodynamics of a spouted bed with an impermeable draft tube for binary particle systems

A spouted bed with an impermeable draft tube was employed to obtain fundamental data of binary mixtures of glass beads for both the operating conditions and the design factors. These data were compared with those for the coarser particle system only. From this view point, minimum spouting velocity, pressure drop, hold-up of solid particles within a draft tube, upward gas flow rate within the annulus and solids circulation rate were determined by changing the total gas flow rate and mass fraction of finer particles as operating parameters and by changing distance of entrainment zone and draft tube diameter as geometric parameters.     

Tubular Assembly Formation Induced by Leucine Alignment along the Hydrophobic Helix of Amphiphilic Polypeptides

The introduction of α-helical structure with a specific helix–helix interaction into an amphipathic molecule enables the determination of the molecular packing in the assembly and the morphological control of peptide assemblies. We previously reported that the amphiphilic polypeptide SL12 with a polysarcosine (PSar) hydrophilic chain and hydrophobic α-helix (l-Leu-Aib)₆ involving the LxxxLxxxL sequence, which induces homo-dimerization due to the concave–convex interaction, formed a nanotube with a uniform 80 nm diameter. In this study, we investigated the importance of the LxxxLxxxL sequence for tube formation by comparing amphiphilic polypeptide SL4A4L4 with hydrophobic α-helix (l-Leu-Aib)₂-(l-Ala-Aib)₂-(l-Leu-Aib)₂ and SL12. SL4A4L4 formed spherical vesicles and micelles. The effect of the LxxxLxxxL sequence elongation on tube formation was demonstrated by studying assemblies of PSar-b-(l-Ala-Aib)-(l-Leu-Aib)₆-(l-Ala-Aib) (SA2L12A2) and PSar-b-(l-Leu-Aib)₈ (SL16). SA2L12A2 formed nanotubes with a uniform 123 nm diameter, while SL16 assembled into vesicles. These results showed that LxxxLxxxL is a necessary and sufficient sequence for the self-assembly of nanotubes. Furthermore, we fabricated a double-layer nanotube by combining two kinds of nanotubes with 80 and 120 nm diameters—SL12 and SA2L12A2. When SA2L12A2 self-assembled in SL12 nanotube dispersion, SA2L12A2 initially formed a rolled sheet, the sheet then wrapped the SL12 nanotube, and a double-layer nanotube was obtained.