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.     

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.     

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     

Structure and reactivity of MoO3-MgO catalysts

Surface of OH groups on reduced MoO₂-MgO catalysts such as $$ - - Mg - - O - - \begin{array}{*{20}c} {||} \\ {Mo} \\ | \\ \end{array} - - OH$$ may act as an active site for hydrogenation of propene. The surface hexa-coordinated Mo⁵⁺ ion (MO _6c ⁵⁺ ) was reduced to a lower number of cation such as Mo⁴⁺ or Mo³⁺ which act as an active site for metathesis of propene.     

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.     

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.     

Graph construction with the maximum number of trees by continuous edge addition

A simple computational algorithm is presented to construct a graph with the maximum number of trees by adding edges one by one. The number of trees of a graph would become an index to estimate the overall reliability of probabilistic communication networks with the same link probabilities. Our procedure, Max-trees, selects one edge that gives the maximum number of trees among edges not included in the original graph. This process is continuously repeated at each step of adding an edge, when we get the sequence of new edges to be added. As examples of the execution results, the edge sequence and the maximum number of trees are shown for two types of starting graph, which are a tree of series edges and a star-shaped tree for nodes n = 7 and 8. To see how many trees these graphs have, the minimum numbers of trees for graphs with the same number of nodes and edges are similarly calculated by the minimum-version algorithm Min-trees. An edge sequence of Max-trees makes long cycles, and that of Min-trees makes cycles of three for as long as possible. The ratio of the maximum number of trees to the minimum number of trees is about 1 to 6 for these examples. This work was presented in part at the 11th International Symposium on Artificial Life and Robotics, Oita, Japan, January 23–25, 2006     

Identification and Field Evaluation of Sex Pheromone Components of the Pear Barkminer Moth, <Emphasis Type="Italic">Spulerina astaurota</Emphasis>

The pear barkminer moth, Spulerina astaurota Meyrick (Gracillariidae: Gracillariinae), is a harmful pest of the Asian-pear tree. Pheromone components of the female were analyzed by gas chromatography (GC) with an electroantennographic (EAG) detector and GC coupled with mass spectrometry. The analyses of a crude pheromone extract and those of a fractionated extract on a Florisil column indicated three EAG-active components, tetradecadien-1-ol, its acetate, and an aldehyde derivative. Characteristic fragment ions in the mass spectra of the dienyl compounds and derivatives with 4-methyl-1,2,4-triazoline-3,5-dione revealed double bonds at the 9- and 11-positions. By comparing the chromatographic behaviors to those of four authentic geometrical isomers, which were synthesized by three different routes starting from 1,8-octanediol or 1,9-nonanediol, the configuration of each natural component was assigned to be 9Z,11Z; i.e., it was concluded that the S. astaurota females secreted (9Z,11Z)-9,11-tetradecadien-1-ol (Z9,Z11-14:OH) as a main pheromone component, and the acetate and aldehyde derivatives (Z9,Z11-14:OAc and Z9,Z11-14:Ald) as minor components. This identification was confirmed by a field evaluation of the synthetic pheromone. While the male moths could be attracted to a lure baited with Z9,Z11-14:OH alone, Z9,Z11-14:OAc showed a strong synergistic effect on the attraction. Among the lures tested, the mixture of alcohol and acetate in a ratio of 7:3 exhibited the strongest attraction. Addition of Z9,Z11-14:Ald in the mixture did not significantly increase the number of males attracted. Furthermore, the field test indicated that some contamination of a geometrical isomer of the alcohol did not impair the activity of the binary mixture with the 9Z,11Z configuration.