PLC-type hybrid external cavity laser integrated with front-monitorphotodiode on Si platform

A planar lightwave circuit (PLC)-type hybrid external cavity laser, integrated with a front-monitor photodiode (PD) on Si has been successfully fabricated. Polymer-embedded grooves are incorporated in the cavity to suppress mode hopping, and the optical power of the laser was stabilised from 18 to 56°C with no mode hopping     

High Performance Ferrous MIM Components Through Carbon and Microstructural Control

This study on metal injection molding considers the combined influences of the type of powder, subsequent debinding and sintering conditions on the carbon control and microstructure for high performance ferrous materials. Carbon retention and sintered microstructure vary significantly with the powder type. Although carbon retention is sensitive to the debinding and sintering atmospheres and conditions, the carbon content can be successfully controlled by adjusting the weight loss after deb'inding. Mechanical properties are also investigated and compared with that of conventional P/M and wrought materials, some factors affecting the properties are discussed taking the microstructure into account. Finally, high performance properties depend on two types of microstructure, one is the fine homogeneous microstructure in the case of high alloy steels and the other is the fine heterogeneous microstructure in the case of low alloy steels.     

Synthesis of [(2'S, 3'S)-bis(hydroxylmethyl)pyrrolidin-1-yl] purine and pyrimidine nucleosides as potential antiviral agents

The enantiomerically pure synthesis of [(2'S, 3'S)-bis(hydroxymethyl)pyrrolidin-1-yl] thymine 17 and -adenine 20 was achieved via construction of the base on the 1-amino-pyrrolidine 15, and their anti-HSV-1 and -2, and anti-HIV-1 activities were evaluated.     

APC, K-ras codon 12 mutations and p53 gene expression in carcinoma and adenoma of the gall-bladder suggest two genetic pathways in gall-bladder carcinogenesis

The pancreatitis-associated proteins (PAPs) are major pancreatic secretory proteins during acute pancreatitis. However, mechanisms of regulation of PAP gene expression are poorly understood, and there is a lack of information regarding mouse PAP gene expression. Herein, we employed Northern blotting and RNase protection assays to measure mouse PAP-I mRNA levels in the normal pancreas and intestine, and in the pancreas during caerulein-induced acute pancreatitis. Unexpectedly, we found that mouse PAP-I mRNA levels are constitutively high in the adult pancreas, as well as in the small intestine. Furthermore, mouse pancreatic PAP-I mRNA levels are rapidly and dramatically down-regulated (3 h) after the initiation of caerulein injections, but slowly return to high levels by 72 h. Interestingly, we found that pancreatic PAP-I mRNA levels are also transiently and dramatically down-regulated after L-buthionine-[S,R]-sulfoximine administration. Thus, a correlation between PAP-I mRNA levels and glutathione levels in the mouse pancreas was demonstrated.     

Design criteria for highly-efficient operation of 1.3-μmInP-based strained-layer multiple-quantum-well lasers at elevatedtemperatures

We derive a basic design rule for highly-efficient operation of 1.3-μm InP-based strained-layer (SL) multiple-quantum-well (MQW) lasers at elevated temperatures on the basis of a self-consistent numerical approach including the Poisson equation and effective-mass equations. Following the derived design rule, high-efficiency (0.55 W/A at 363 K) and high-power (over 35 mW at 363 K) InP-based SL-MQW lasers have been fabricated     

Decomposition of NO on Na+-modified MgO evidenced by ESR and temperature programmed desorption (TPD)

The decomposition of NO to N₂O is accompanied by the formation of O^– over a Na⁺-modified MgO surface at moderated temperatures. The importance of the interaction of (Na⁺) _n (n2) clusters and MgO surface is highlighted.     

Mechanical properties of injection molded Fe-6% Ni-0.4% C steels with varying Mo contents of 0.5 to 2%

In our previous studies, sintered and heat-treated alloy steels (Fe−6Ni−0.5Mo−0.4C (mass%)) produced by a MIM process showed excellent mechanical properties of 2000 MPa tensile strength and 5% elongation. This was attributed to the solid solution strengthening and the mezzo-heterogenous microstruture, which consisted of martensite or retained austenite (Ni and Mo rich phases) surrounded by a network of tempered martensite. This study has been performed to clarify the effect of Mo on the mezzo-heterogeneous microstructure and the mechanical properties of MIM processed and sintered alloy steels (Fe−6Ni−0.4C) with varying Mo content (0.5–2 mass%). The tensile properties of the heat-treated steels with added 2 mass% Mo were lower than those of the steels with added 0.5 mass% Mo. The reduction in the tensile properties, particularly the appearance of large pores formed at the original location of Mo power through the transient liquid phase formation and the low hardness of the matrix, was due to the low sintered density. By using mechanically milled fine Ni and Mo powders, the heat-treated steel (Fe−6Ni−2Mo−0.4C) showed excellent properties, including tensile strength of 1800 MPa and ductility of 2.2% elongation. This article is based on a presentation made in the symposium “The 3rd KIM-JIM Joint Symposium on Advanced Powder Materials”, held at Korea University, Seoul, Korea, October 26–27, 2001 under auspices of The Korean Institute of Metals and Materials and The Japan Institute of Metals.     

Effect of SO42− on catalytic activity of Fe2O3 for hydrocracking of coal

The catalytic activity of Fe₂O₃for the hydrocracking of a bituminous coal at 673K increases when a small amount of SO₄^2? is included in the catalyst. The effect of SO₄^2? is marked in the formation of resins, stronger polar compounds and asphaltenes.     

Shape selective catalytic behaviors of nickel ion-exchanged layered potassium niobate

The alcohol decomposition and olefin hydrogenation on the hydrogen-treated Ni ion-exchanged (exchange degree, 30%) potassium niobate (Ni-K₄Nb₆O₁₇) were performed. Formation of propene from i-propanol on Ni-K₄Nb₆O₁₇ was much smaller than that observed on bulk Nb₂O₅, while the olefin yields from ethanol and n-propanol were almost the same on both catalysts. The 1- butene hydrogenation did not proceed on Ni-K₄Nb₆O₁₇, whereas propene hydrogenation took place rapidly on the same catalyst at 80°C.

The formation of the acid sites and Ni metallic sites by hydrogen treatment at 300 °C was proposed by using temperature-programmed reduction (TPR) and extended X-ray absorption fine structure (EXAFS). These results suggest that Hg₂-treated Ni-K₄Nb₆O₁₇ acts as a shape selective acid- and metal-catalyst at suitable reaction temperatures.     

Internal gravity wave resonance of thermal convection fields in a square cavity with heat‐flux vibration

In this paper, the thermal convection field and its resonance phenomena in a square cavity with sinusoidal heat‐flux vibration were numerically investigated. As the angular velocity ω is changed, the thermal convection field at Pr = 0.71,Ra = 10⁶ is found to be classified into 5 regions. In particular, the field has the local maximum relative amplitude of midplane Nusselt's number at ω_c = 350, which corresponds to the angular velocity of internal gravity wave ω_r estimated by a theoretical equation proposed by Thorpe. This shows that the local enhancement is induced by internal gravity wave resonance. Such correspondence is observed for Ra ≥ 10⁵,Ra ≥ 10⁶ for Pr = 0.71, 7.1, respectively. For these ranges of Ra we propose a correlation equation, a function of Pr and Gr only, to estimate the resonant angular velocity. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(5): 309–322, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20122