Production of Hydrogen Storage Alloy of Mg2NiH4 by Hydriding Combustion Synthesis in Laboratory Scale

A laboratory scale production method for hydrogen storage alloy of Mg₂NiH₄ by hydriding combustion synthesis was investigated. In this study, cylinders of magnesium and nickel mixture powder, compressed at different pressures, and a powder mixture of metals, without the compressive treatment, were used as a raw material. The products were examined by X-ray diffraction (XRD) and scanning-electron microscopy (SEM). The XRD results indicated that pure Mg₂NiH₄ was simply obtained not only from the compressed cylinders, but also from the powder. There was no significant effect of the compressive pressure of the cylinder on the composition of the final products. However, SEM observations showed that the compressed sample and the powder are clearly different, in spite of the same product composition. The results also revealed a possibility of new production system of Mg₂NiH₄ using hydriding combustion synthesis, with many benefits of simple pretreatment, including: simple equipment, short operating time, high-quality product, and energy savings.     

DEPOSITION OF DIAMOND FOR CUTTING TOOL APPLICATIONS

The poor adhesion of diamond film to substrates is one of the major problems for practical use in a cutting tool (1-4). in this study, sintered tungsten carbide (WC) body without Co metal, not cemented carbide, was used as the substrate (5), and the effects of surface decarburization of the substrate for improvement in the adhesion of diamond films were investigated. The surface decarburization and diamond coating were carried out in a microwave plasma CVD system. From the results of several adhesion tests, including the cutting tests, it is concluded that the good adhesion is obtained by surface decarburization of the substrate before diamond coating. The reasons for improvement in adhesion are considered by observing the interface structure between the film and the substrate. The damage mechanism of diamond coating on cutting an AI-18%Si alloy with increasing cutting speed is also discussed.     

Delta3,5-delta2,4-dienoyl-CoA isomerase from rat liver. Molecular characterization

rECH1, a recently identified rat cDNA (FitzPatrick, D. R., Germain-Lee, E., and Valle, D. (1995) Genomics 27, 457-466) encodes a polypeptide belonging to the hydratase/isomerase superfamily. We modeled the structure of rECH1 based on rat mitochondrial 2-enoyl-CoA hydratase 1. The model predicts that rECH1p has the hydratase fold in the core domain and two domains for interaction with other subunits. When we incubated 3,5,8,11, 14-eicosapentaenoyl-CoA with purified rECH1p, the spectral data suggested a switching of the double bonds from the Delta3-Delta5 to the Delta2-Delta4 positions. This was confirmed by demonstrating that the product was a valid substrate for 2,4-dienoyl-CoA reductase. These results indicate that rECH1p is Delta3,5-Delta2,4-dienoyl-CoA isomerase. Subcellular fractionation and immunoelectron microscopy using antibodies to a synthetic polypeptide derived from the C terminus of rECH1p showed that rECH1p is located in the matrix of both mitochondria and peroxisomes in rat liver. Consistent with these observations, the 36,000-Da rECH1p has a potential N-terminal mitochondrial targeting signal as well as a C-terminal peroxisomal targeting signal type 1. Transport of the protein into the mitochondria with cleavage of the targeting signal results in a mature mitochondrial form with a molecular mass of 32,000 Da; transport to peroxisomes yields a protein of 36,000 Da.     

Advanced endocrine cell carcinoma of the gallbladder: a patient with 12-year survival

Gallbladder carcinoid is a rare disease. In previous reports, classical carcinoid, an entity with a good prognosis, has not been distinguished from endocrine cell carcinoma, a tumor associated with marked cell atypia and mitosis, and a poor prognosis. The patient was a 66 year old woman who presented to our hospital with a chief complaint of jaundice. Pre-operatively, she was diagnosed as having advanced gallbladder carcinoma invading the liver and the hepatic hilus. The patient underwent right hepatic trisegmentectomy with en bloc resection of the caudate lobe and extrahepatic bile ducts, extended lymph node clearance and left hepaticojejunostomy. Histopathological examination showed positive Grimelius staining, marked mitosis, and intense atypism, hence, the tumor was diagnosed as an endocrine cell carcinoma. Twelve years after surgery, the patient is healthy, without any sign of recurrence. We present this novel case of long-term survival and review the literature.     

Molecular analysis of mutations induced by acrolein in human fibroblast cells using supF shuttle vector plasmids

Types of mutations induced by acrolein in the supF gene on the shuttle vector plasmid pMY189 replicated in normal human fibroblast cells were examined. Base sequence analysis of 92 plasmids with mutations in the supF gene revealed that the majority of the mutations were base substitutions (76%) and the others were deletions and insertions (24%). Single base substitutions were most frequently found (46%), while multiple base substitutions were 18% and tandem (two adjacent) base substitutions were 12% of the mutations. Of the base substitution mutations, G:C to T:A transversions were 44% and G:C to A:T transitions were 24%. The mutations were distributed not randomly but located at several hotspots. Acrolein produced DNA intra-strand cross-links between guanine residues, which might be responsible for rather high induction of the tandem base substitution mutations.     

Phase Equilibria and Phase Transition of the Ni–Fe–Ga Ferromagnetic Shape Memory Alloy System

Phase equilibria and martensitic and magnetic transitions of the β (B2 and L2₁) phase in the Ni–Fe–Ga system were investigated. The b phase was found to be in equilibrium with the γ (A1 structure) or γ′ (L1₂ structure) phase. The Curie temperature, T _c , equilibrium temperature, T _o 5 (Ms + Af)/2, martensitic transition starting temperature, M _s , and reverse transition finishing temperature, Af , of the β single–phase alloys were sensitive to the Fe and Ga compositions. The Fe substitution for Ni decreased and increased the T _o and T _c , respectively. The Ga substitution for Ni or Fe decreased both the T _o and T _c . The entropy change accompanying the reverse martensitic transition showed compositional dependence due to the magnetic contribution. The saturation magnetization I _s of the Ni–Fe–Ga system showed a strong dependence on the magnetic valence Z _M . The Is values of the Ni–Fe–Ga alloys annealed at 1023 K showed the same Z _m dependence as other ferromagnetic shape memory alloy (FSMA) systems. This article is based on a presentation made in the symposium entitled "Phase Transformations in Magnetic Materials," which occurred during the TMS Annual Meeting, March 12-16, 2006, in San Antonio, Texas, under the auspices of the Joint TMS–MPMD and ASMI–MSCTS Phase Transformations Committee.     

Unusual ligand structure in Ni-Fe active center and an additional Mg site in hydrogenase revealed by high resolution X-ray structure analysis

BACKGROUND: The hydrogenase of Desulfovibrio sp. catalyzes the reversible oxidoreduction of molecular hydrogen, in conjunction with a specific electron acceptor, cytochrome c3. The Ni-Fe active center of Desulfovibrio hydrogenase has an unusual ligand structure with non-protein ligands. An atomic model at high resolution is required to make concrete assignment of the ligands which coordinate the Ni-Fe center. These in turn will provide insight into the mechanism of electron transfer, during the reaction catalysed by hydrogenase. RESULTS: The X-ray structure of the hydrogenase from Desulfovibrio vulgaris Miyazaki has been solved at 1.8 A resolution and refined to a crystallographic R factor of 0.229. The overall folding pattern and the spatial arrangement of the metal centers are very similar to those found in Desulfovibrio gigas hydrogenase. This high resolution crystal structure enabled us to assign the non-protein ligands to the Fe atom in the Ni-Fe site and revealed the presence of a Mg center, located approximately 13 A from the Ni-Fe active center. CONCLUSIONS: From the nature of the electron-density map, stereochemical geometry and atomic parameters of the refined structure, the most probable candidates for the four ligands, coordinating the Ni-Fe center, have been proposed to be diatomic S=O, C triple bond O and C triple bond N molecules and one sulfur atom. The assignment was supported by pyrolysis mass spectrometry measurements. These ligands may have a role as an electron sink during the electron transfer reaction between the hydrogenase and its biological counterparts, and they could stabilize the redox state of Fe(II), which may not change during the catalytic cycle and is independent of the redox transition of the Ni. The hydrogen-bonding system between the Ni-Fe and the Mg centers suggests the possible.     

Clinical and serological study of tsutsugamushi disease in northern Osumi, Kagoshima Prefecture

We report 34 cases of tsutsugamushi disease seen from 1989 to 1993 at Yagi Clinic, northern Osumi, Kagoshima Prefecture. Nineteen patients (55.9%) showed the highest antibody titers against the Kawasaki strain Orientia tsutsugamushi (Ot) and 13 (38.2%) against the Kuroki strain Ot. It is suggested that two antigenic types (Kawasaki and Kuroki) of Ot were distributed in Kagoshima Prefecture, and the Kawasaki type Ot more or less dominates Kuroki type Ot. There was no difference in clinical features between the two groups of patients.