Okadaic acid inhibits alkaline phosphatase activity in MC3T3-E1 cells

Alkaline phosphatase activity is regulated by various hormones and growth factors at least in part through the phosphorylation of target proteins during the bone cell differentiation. To investigate the role of protein phosphorylation in alkaline phosphatase activity in MC3T3-E1 osteoblast, we used okadaic acid which is a potent specific inhibitor of serine/threonine protein phosphatases to type 1 and 2A. Alkaline phosphatase activity in cellular layer was measured by spectrophotometer using p-nitrophenyl phosphate as substrate and data were expressed as p-nitrophenyl of nmol/min/mg of protein. Okadaic acid (1-50 ng/ml) caused the inhibition of alkaline phosphatase activity in MC3TC-E1 cells. At 50 ng/ml of okadaic acid showed the maximal inhibitory effect on alkaline phosphatase activity. Okadaic acid (50 ng/ml) also inhibited alkaline phosphatase activity in all differentiation stages. These results indicate that okadaic acid inhibits alkaline phosphatase activity in MC3T3-E1 cells.     

Kinetics of the reaction between hydrogen sulfide and lime particles

The reaction between hydrogen sulfide and lime is important, among others, as a component reaction of the hydrogen reduction of metal sulfides in the presence of lime, and in the desulfurization of fossil fuels. The results of experiments on the kinetics of this reaction are presented in this paper. The experiments were carried out in the temperature range 873 to 1073 K, using a thermogravimetric analysis technique. A “pore blocking” model was found to fit the reaction rate, which was initially rapid and leveled off at less than the complete conversion. An activation energy of 76.1 kJ/mol (18.2 kcal/g-mole) was obtained. The reaction was first order with respect to hydrogen sulfide concentration in a gaseous mixture with hydrogen. A higher initial moisture content in the calcium oxide particles resulted in a considerably higher reaction rate. Formerly Graduate Student in the Department of Metallurgy and Metallurgical Engineering, University of Utah     

Simultaneous fluid-solid reactions in porous solids: Reactions between one solid and two fluid reactants

A general model describing simultaneous independent reactions between one solid reactant and two fluid reactants is presented. Such reaction systems ar attention in the areas of oil shale retorting, direct reduction of metal oxides with reformed natural gas, coal gasification, etc.The model has been formulated in general terms so as to allow the incorporation of specific details of an actual system. The law of additive reaction t previously proposed for single fluid-solid reactions has been applied to the reaction system under consideration, and it has yielded useful approximate solutions for various aspects of the simultaneous reactions, which otherwise must be obtained by numerical methods.     

The selective oxidation of mixed metal sulfides with lime in the presence of steam without emitting sulfur-containing pollutants

The selective oxidation of mixed metal sulfides with lime in the presence of steam was studied as a function of the mixing ratio of the constituents, temperature, and steam concentration. Two combinations of samples were used in this study: ZnS/PbS/CaO and ZnS/FeS/CaO. The steam oxidizes one or both of the metal sulfides, and the hydrogen sulfide produced reacts with lime to form calcium sulfide and regenerate steam. There is no net consumption or generation of gaseous species; therefore, this process can be carried out in a closed system. The free energy of the reaction is negative only for certain metal sulfides, and thus selective oxidation for mixed sulfides can be achieved. An overall rate equation developed in this work satisfactorily predicted the experimental data obtained in the temperature range 823 to 1113 K. The potential implications of the results of this work in the treatment of complex sulfide ores are discussed. This paper is based on a presentation made in the T.B. King Memorial Symposium on “Physical Chemistry in Metals Processing” presented at the Annual Meeting of The Metallurgical Society, Denver, CO, February, 1987, under the auspices of the Physical Chemistry Committee and the PTD/ISS.     

Successive gas-solid reaction model for the hydrogen reduction of cuprous sulfide in the presence of lime

As an alternative to conventional smelting processes for producing metals from sulfide ores, which suffer from SO₂ emission problems, direct reduction in the presence of lime has in recent years attracted much attention. In this work, a mathematical model of successive gas-solid reactions in a porous pellet has been applied to the hydrogen reduction of cuprous sulfide (Cu₂S) in the presence of lime. The model has been formulated by incorporating the intrinsic kinetics of the individual reactions obtained from separate experiments, and compared with the experimental results on the hydrogen reduction of chalcocite mixed with lime particles. The model predictions were in good agreement with experimental measurements of the overall rate of reaction and the degree of sulfur fixation over a wide range of experimental conditions. The mathematical model not only can predict the performance of a given system but also enables one to design the optimum pellet properties and reaction conditions in terms of the reaction rate and sulfur fixation. Formerly Graduate Student in the Department of Metallurgy and Metallurgical Engineering, University of Utah.     

Improved recovery characteristics of ISFET glucose sensor usingelectrolysis method

The hydrogen ions present in an enzyme-immobilised membrane are diminished by hydroxide ions generated by a reduction potential. The recovery time of an ISFET glucose sensor using an electrolysis method has been reduced to <2 min in contrast to the 10 or 20 min required using a conventional method     

Unsteady-state absorption of CO2 into w/o emulsion with aqueous alkaline liquid droplets

Unsteady-state absorption of CO₂ into w/o emulsion was studied by experimental measurements and prediction from mathematical modeling. Absorption experiments were performed by using a stirred vessel with a flat gas-liquid interface under 0.101 MPa and 25 °C. Continuous phase was benzene that has larger solubility than water. Dispersed phase was an aqueous solution of NaOH and AMP. The effects of reactant concentration, size of emulsified droplets, volume fraction of continuous phase and stirring speed on the absorption rate of CO₂ were investigated. In the mathematical model, the mechanism of CO₂ absorption into the continuous phase through a gas-liquid interface was described on the basis of the penetration model, while the subsequent absorption/reaction in the dispersed aqueous droplets was modeled by the film model.     

Removal of Carbonaceous Residue with Wet Hydrogen in Greensheet Processing for Multilayer Ceramic Module: II, Reaction in Large Modules Influenced by Pore Diffusion and Mass Transfer

An experimental and mathematical investigation of the removal of carbonaceous residue deposited on the ceramic substrate in the fabrication of multilayer ceramic modules has been conducted. Such carbonaceous residue is formed when the organic binder is pyrolyzed during the firing of greensheets. This paper is the second of a two-part series that reports on and discusses the principal findings of the investigation. In this paper we describe the removal of carbonaceous residue from large blocks of the multilayer ceramic module in which the diffusion of gaseous species may play a role. A mathematical model is developed using the Law of Additive Reaction Times for fluid-solid reactions, which incroporates the effects of intrinsic chemical kinetics, pore diffusion, and external mass transfer. This law gives an approximate solution to the governing equations which describe the removal of carbonaceous residue from the MLC module during firing.     

Constituent redistribution in U-Pu-Zr fuel during irradiation

The thermo-migration fluxes of U, Pu and Zr in U-Pu-Zr metallic alloy fuel during irradiation in the Experimental Breeder Reactor II (EBR-II) were calculated using the constituent redistribution profiles measured in postirradiation examinations. Based on these fluxes, the diffusion coefficients, and the sums of heat of transport and enthalpy of solution for the γ, γ+ζ and δ+ζ phases in U-Pu-Zr were obtained. Using these data, the predicted concentration redistribution profiles are consistent with the measurements. The effect of minor actinide (Am and Np) addition was also examined. Am migration generally followed that of Zr with local precipitation, while Np behaved similarly to Pu.