Bonded thin cylinder magnets using Sm-Fe-N anisotropic powder
Anisotropic bonded Sm-Fe-N thin cylinder magnets have been developed by an injection-molding technology using unsaturated polyester resin, because thin and high-performance magnets are needed in order to downsize the motor. A special point for forming was a control of the rate of shrinkage. A multioriented cylinder magnet of 0.8 mm thickness was made by an insertion forming an aluminum column of 18.4 mm diameter and 18 mm height. A radial-oriented cylinder magnet of 15 mm outer diameter, 16 mm height, and 0.5 mm thickness was also made.
Preparation and characterization of Sm2Fe17 alloy in LiF-CaF2-SmF3 molten salt
Abstract A suitable temperature range of Sm2Fe17 alloy formed only was chosen to investigate the electroreduction of Sm3+ on molybdenum and iron electrode in LiF-CaF2-SmF3 molten salt, which were studied by CV and SWV at different temperatures and concentrations of Sm3+. The reduction of Sm3+ to Sm0 on the iron electrode included two steps. Firstly, a soluble-soluble reaction appears at −0.33 V vs. Cr/Cr2O3 corresponds to the electroreduction of Sm3+ to Sm2+. The electroreduction of Sm3+ to Sm2+ is a reversible process, which is controlled by the diffusion of Sm3+ in the LiF-CaF2-SmF3 molten salt. Secondly, Sm2+ can be reduced at −0.78 V vs. Cr/Cr2O3 on the iron electrode in LiF-CaF2-SmF3 molten salt due to a lower activity of metallic samarium in the Sm2Fe17 alloy than that of samarium metal, and that makes samarium in Sm-Fe alloy more stable while that of Sm2+ could be not reduced by a molybdenum electrode. By experiment of potentiostatic electrolysis it was confirmed that the cathode product from LiF-CaF2-SmF3 melts at −1 V vs. Cr/Cr2O3 for 4 h is a thin layer metallic plate only composing Sm2Fe17 alloy.
A quantitative measure of nitrifying bacterial growth.
Nitrifying bacteria convert ammonia (NH3) to nitrate (NO3-) in a nitrification reaction. Methods to quantitatively separate the growth rate of these important bacterial populations from that of the dominant heterotrophic bacteria are important to our understanding of the nitrification process. The changing concentration of ammonia is often used as an indirect measure of nitrification but ammonification processes generate ammonia and confound this approach while heterotrophs remove nitrate via denitrification. Molecular probe methods can tell us what proportion of the microbial community is nitrifying bacteria but not their growth rate. The technique proposed here was able to quantify the growth rate of the nitrifying bacterial populations amidst complex ecological processes. The method incubates [methyl-3H] thymidine with water samples in the presence and absence of an inhibitor of nitrification-thiourea. The radioactively labeled DNA in the growing bacteria was extracted. The rate of incorporation of the label into the dividing bacterial DNA was used to determine bacterial growth rate. Total bacterial community growth rates in full-scale and pilot-scale fixed-film nitrifying reactors and an activated sludge reactor were 2.1 x 10(8), 4.1 x 10(8) and 0.4 x 10(8)cell ml(-1)d(-1), respectively; the growth rate of autotrophic-nitrifying bacteria was 0.7 x 10(8), 2.6 x 10(8) and 0.01 x 10(8)cell ml(-1)d(-1), respectively. Autotrophic-nitrifying bacteria contributed 30% and 60% of the total bacterial community growth rate in the nitrifying reactors whereas only 2% was observed in the activated sludge reactor that was not designed to nitrify. The rates of ammonia loss from the nitrifying reactors corresponded to the rate of growth of the nitrifying bacteria. This method has the potential to more often identify factors that enhance or limit nitrifying processes in both engineered and natural aquatic environments.