Kinetic Study on the Hydrogen Reduction of Some Nonferrous Metal Oxides

To investigate the kinetic aspects in reactions involving solids, the reduction rate of nickel oxide by hydrogen was measured by means of thermo-balance. The rate is described by 2/3 order kinetic law and has an activation energy of 25 kcal/mol.. From the results of Delmon's interruption technique and other kinetic examination, it may be assumed that the reduction will proceed according to the spherical surface contracting model. The reduction rate of several ilmenite ores was also measured by the same means and the profiles of oxygen concentration in a section of reduced particles were examined by means of X-ray micro-analyser to inspect the reduction progress. It was found that the reduction process consists of two stages proceeding successively, where in the first stage, the reduction of iron oxide besides ilmenite component occurred, secondly, the latter component was reduced and those kinetics were also described approximately by 2/3 order law

Thermodynamic Properties of Wustite (FeO₁₊y)

E.m.f. measurements of the cell, Pt/FeO₁₊y/ZrO₂ (CaO)/Ni-NiO/Pt, have been carried out to investigate the thermodynamic characteristics of wustite (FeO₁₊y). From these results, the relationship between temperature, oxygen pressure and composition of wustite and the phase boundaries of wustite phase in the binary system Fe-O were obtained and compared with those given by Darken and Gurry. The thermodynamic quantities such as activities of iron and oxygen in wustite, partial molar enthalpies and entropies of solution of oxygen in wustite and free energy of formation of magnetite were also evaluated. The defect sturcture of wustite was discussed in relation with the Po₂ dependence of cation vacancy concentration of wustite

Role of intron 1 in smooth muscle α-actin transcriptional regulation in activated mesangial cells in vivo

Role of intron 1 in smooth muscle α-actin transcriptional regulation in activated mesangial cells in vivo.BackgroundThe activation of glomerular mesangial cells is one of the early, important features of progressive glomerular disease. Smooth muscle α-actin (SMαA) is an excellent marker of activated mesangial cells. However, the mechanisms of SMαA regulation are only available from in vitro investigation.MethodsWe examined in vivo promoter analysis of the SMαA gene-utilizing transgenic mice harboring different promoter regions of the SMαA gene fused to chloramphenicol acetyl transferase (CAT). CAT activities were tested in primary cultured mesangial cells and in glomerular legions of Habu venom glomerulonephritis.ResultsThe DNA sequence -891 to +3828, which contains exon 1, intron 1, and the first 14bp of exon 2 in addition to the 5′-flanking sequence of the SMαA gene, induced high levels of transcription in activated mesangial cells in in vivo habu venom glomerulonephritis and in cultured mesangial cells derived from transgenic mice. The DNA region -891 to -124 was a positive element in mesangial cells derived from transgenic mice. Deletions (3316 or 137bp) in intron 1 reduced transcription to undetectable levels. The 137bp sequence is highly conserved among several species, containing one CArG box element, which is one of the key motifs for transcriptional activation of contractile-related proteins. In vitro transfection analysis failed to demonstrate these positive effects of intron 1 and region -891 to -124.ConclusionsIn vivo promoter analysis of the SMαA gene provided new information about the transcriptional regulation of SMαA in activated mesangial cells. The DNA region -891 to -124 has a positive effect on SMαA transcription in cultured mesangial cells. The intron 1 region (+1088 to +1224) plays a pivotal role in SMαA transcription in activated mesangial cells in vivo. Further analysis of this conserved region in intron 1, including the CArG motif, will be of great value in understanding the molecular mechanisms of mesangial activation