In this article, we prove that the Clifford torus S^1（√1-r^2）×^n-1（r） is the only closed hypersurface in the unit sphere S^n＋1（1） with infinite fundamental group, which satisfy r^2≥（n-1）/n,RicM≤C_（H...In this article, we prove that the Clifford torus S^1（√1-r^2）×^n-1（r） is the only closed hypersurface in the unit sphere S^n＋1（1） with infinite fundamental group, which satisfy r^2≥（n-1）/n,RicM≤C_（H）,and S≤S＋（H）.Moreover, we give a characterization of Clifford torus S^1（√1-r^2）×^n-1（r） with r^2=2n（1＋H^2）^-2（n-1）＋nH^2＋｜H｜√n^2H^2＋4（n-1）.展开更多
Coal fly ash originated from coal combustion has high concentrations of metals. If suitable leaching techniques are identified, then coal fly ash could serve as a useful source of valuable minerals including rare eart...Coal fly ash originated from coal combustion has high concentrations of metals. If suitable leaching techniques are identified, then coal fly ash could serve as a useful source of valuable minerals including rare earth elements (REEs). In this study, three microbial strains, Candida bombicola, Phanerochaete chrysosporium and Cryptococcus curvatus were tested on their performance of leaching trace elements and REEs from fly ash. Through comparing mineral loss and leaching efficiencies resulting from indirect leaching or use of the culture supernatant, C. bombicola was identified to be the best leading to the highest mineral loss and extracting efficiencies of trace elements and REEs among the three strains. The highest mineral loss observed from using the supernatant of this yeast strain was 59.7%. Among all trace elements, As and Mo had the highest leaching efficiency of 80.9% and 79.5%. respectively. The same leaching test led to 67.7% of Yb and 64.6% of Er dissolved from the ash. This study, thus, demonstrated that bioleaching is feasible for leaching metals out of fly ash. The C. bombicola strain deserves further investigation due to its robust actions on metal leaching.展开更多
基金supported by the Foundation of XuzhouNormal University (08XLA02)the Education Department of Jiangsu Province (07KJB110115)
文摘In this article, we prove that the Clifford torus S^1（√1-r^2）×^n-1（r） is the only closed hypersurface in the unit sphere S^n＋1（1） with infinite fundamental group, which satisfy r^2≥（n-1）/n,RicM≤C_（H）,and S≤S＋（H）.Moreover, we give a characterization of Clifford torus S^1（√1-r^2）×^n-1（r） with r^2=2n（1＋H^2）^-2（n-1）＋nH^2＋｜H｜√n^2H^2＋4（n-1）.
文摘Coal fly ash originated from coal combustion has high concentrations of metals. If suitable leaching techniques are identified, then coal fly ash could serve as a useful source of valuable minerals including rare earth elements (REEs). In this study, three microbial strains, Candida bombicola, Phanerochaete chrysosporium and Cryptococcus curvatus were tested on their performance of leaching trace elements and REEs from fly ash. Through comparing mineral loss and leaching efficiencies resulting from indirect leaching or use of the culture supernatant, C. bombicola was identified to be the best leading to the highest mineral loss and extracting efficiencies of trace elements and REEs among the three strains. The highest mineral loss observed from using the supernatant of this yeast strain was 59.7%. Among all trace elements, As and Mo had the highest leaching efficiency of 80.9% and 79.5%. respectively. The same leaching test led to 67.7% of Yb and 64.6% of Er dissolved from the ash. This study, thus, demonstrated that bioleaching is feasible for leaching metals out of fly ash. The C. bombicola strain deserves further investigation due to its robust actions on metal leaching.
