Response surface methodology (RSM) is utilized to analyze and optimize the experimental condition of V(Ⅴ) removal in single chamber microbial fuel cell (MFC). The influences of initial vanadium concentration, COD and electrolyte conductivity on V(Ⅴ) removal efficiencies are investigated when sodium acetate is adopted as carbon source in single chamber MFC. The results of RSM with three factors at three levels reveal that the initial vanadium concentration has the most significant effect on V(Ⅴ) removal efficiencies, followed by the COD, whereas the influence of the electrolyte conductivity is minimal. The optimal experimental condition obtained by RSM is initial V(Ⅴ) concentration of 75.44 mg/L, COD of 1007.48 mg/L and electrolyte conductivity of 11.98 mS/cm, in which condition the theoretical maximum V(Ⅴ) removal efficiency of 80.31% can be achieved. Verification test is also conducted and the results further confirm the reliability of the optimization. The results of the present study will promote the application of MFC in the remediation of vanadium contaminated groundwater.

The matrix equation X + A ^* X^-2 A = I is studied. Some necessary and sufficient conditions for the existence of a positive definite solution of this equation are derived. Based on them, some properties of the coefficient matrix A are presented when the matrix equation has a positive definite solution.

Rice dwarf virus full genome 12 gene segments were cloned and 25000 nucleotides were sequenced. The gene functions of each segment were analyzed according to amino acid sequences and experimental data. The coding regions of segments S6, S9, S10 and S11 encoding nonstractural proteins were cloned into expression vector pTricHisA, pBV221, pTric HisB, pBV221, respectively. The expressed products were analyzed by SDS-PAGE and further confirmed by Western-blotting. Using the E.coli expression products, the function of Pns11 was studied. The results showed that Pns11 is a ds-/ss-RNA and DNA binding protein and it may play very important roles in virus genome assortment or packaging. Gene segments S2, S7, S8 and S9 which encode virus most outer coat protein, minor core protein, outer coat protein and nonstructural protein were transferred into rice via biolistic bombardment and regenerated rice plants were obtained. The resistance to RDV infection of these transgenic rice plants are in testing.