Synthesis of protective Mo-Si-B coatings in molten salts and their oxidation behavior in an air-water mixture

The formation of various phases during boronizing of silicided molybdenum substrates (MoSi2/Mo) was investigated. Boronizing treatments were conducted in molten salts under an inert gas atmosphere in the 700-1000 degrees C temperature range for 3-7 h. Depending on the process type (non-current or electrochemical) and molten salt temperature, the formation of different boride phases (MoB, Mo2B5, MoB2, MoB4) was observed. At the same time, substantial oxidation of the bulk molybdenum disilicide phase (MoSi2) to the Mo5Si3 phase was observed in non-current boronizing. The oxidation resistance of the coatings was investigated by the weight change in an air-water (2.3 vol.%) mixture at a temperature of 500 degrees C for a period up to 700 h. Results indicated that a two-phase microstructure consisting of the MoSi2, matrix phase with 12-15 wt.% of the MoB4 phase greatly improved the oxidation resistance of the molybdenum substrates. The weight gain rate observed was 6.5 center dot 10(-4) mg/cm(2) h. (c) 2006 Elsevier B.V. All rights reserved.

Di-mu-chloro-bis({2-[(2-hydroxyethyl)iminomethyl]phenolato-kappa N-3,O,O '} nickel(II)) methanol solvate

The title compound, [Ni2Cl2(C9H10NO2)(2)]center dot CH3OH, is a dinuclear unit built up by two nickel(II) complexes, bridged by two Cl atoms. The coordination geometry around each Ni-II atom can be considered as distorted square-pyramidal, with the tridendate chelate Schiff base ligands coordinating in a trans conformation through their imine N atom and phenoxy and alkoxy O atoms.

Microelectrode Voltammetry of Dioxygen Reduction in a Phosphonium Cation-Based Room-Temperature Ionic Liquid: Quantitative Studies

Microelectrode voltammetry is used to study the electrochemical reduction of dioxygen, O-2, in the room-temperature ionic liquid trihexyl(tetradecyl)phosphonium trifluorotris(pentafluoroethyl)phosphate [P6,6,6,14][FAP]. The nature of the unusual voltammetric waves is quantitatively modeled via digital simulation with the aim of clarifying apparent inconsistencies in the literature. The reduction is shown to proceed via a two-electron reaction and involve the likely capture of a proton from the solvent system. The oxidative voltammetric signals seen at fast scan rates are interpreted as resulting from the reoxidation of HO2 center dot. In the presence of large amounts of dissolved carbon dioxide the reductive currents decrease by a factor of ca. two, consistent with the trapping of the superoxide radical, O-2(center dot), intermediate in the two-electron reduction process.

Selective induction of apoptosis by the pyrrolo-1,5-benzoxazepine 7-[[dimethylcarbamoyl]oxy]-6-(2-naphthyl)pyrrolo-[2,1-d] (1,5)-benzoxazepine (PBOX-6) in Leukemia cells occurs via the c-Jun NH2-terminal kinase-dependent phosphorylation and inactivation of Bcl-2 and Bcl-XL

Overexpression of the Bcl-2 proto-oncogene in tumor cells confers resistance against chemotherapeutic drugs. In this study, we describe how the novel pyrrolo-1,5-benzoxazepine compound 7-[[dimethylcarbamoyl]oxy]-6-(2-naphthyl)pyrrolo-[2,1-d] (1,5)-benzoxazepine (PBOX-6) selectively induces apoptosis in Bcl-2-overexpressing cancer cells, whereas it shows no cytotoxic effect on normal peripheral blood mononuclear cells. PBOX-6 overcomes Bcl-2-mediated resistance to apoptosis in chronic myelogenous leukemia (CML) K562 cells by the time- and dose-dependent phosphorylation and inactivation of antiapoptotic Bcl-2 family members Bcl-2 and Bcl-XL. PBOX-6 also induces Bcl-2 phosphorylation and apoptosis in wild-type T leukemia CEM cells and cells overexpressing Bcl-2. This is in contrast to chemotherapeutic agents such as etoposide, actinomycin D, and ultraviolet irradiation, whereby overexpression of Bcl-2 confers resistance against apoptosis. In addition, PBOX-6 induces Bcl-2 phosphorylation and apoptosis in wild-type Jurkat acute lymphoblastic leukemia cells and cells overexpressing Bcl-2. However, Jurkat cells containing a Bcl-2 triple mutant, whereby the principal Bcl-2 phosphorylation sites are mutated to alanine, demonstrate resistance against Bcl-2 phosphorylation and apoptosis. PBOX-6 also induces the early and transient activation of c-Jun NH2-terminal kinase (JNK) in CEM cells. Inhibition of JNK activity prevents Bcl-2 phosphorylation and apoptosis, implicating JNK in the upstream signaling pathway leading to Bcl-2 phosphorylation. Collectively, these findings identify Bcl-2 phosphorylation and inactivation as a critical step in the apoptotic pathway induced by PBOX-6 and highlight its potential as an effective antileukemic agent.