Fourteen strains of Aspergillus versicolor and 2 strains of A. nidulans were screened for sterigmatocystin (ST) production on a semi-synthetic solid substrate by high performence liquid chromatography (HPLC) analysis....Fourteen strains of Aspergillus versicolor and 2 strains of A. nidulans were screened for sterigmatocystin (ST) production on a semi-synthetic solid substrate by high performence liquid chromatography (HPLC) analysis. Two strains of A. versicolor producing ST at 550.5 mg.kg-1 substrate and 1160.8 mg·kg-1 substrate were selected to inoculate 4 kg solid ST-producing media. After 30 days stationary incubation at 28 ℃ in the dark, 2271.6 mg of pale-yellow needle-shaped crystals were isolated and purified from the culture with a procedure applying column chromatography and recrystallization method. The crystal was proved to be sterigmatocystin by spectroanalysis and some physico-chemical analysis. The purity of the final material obtained were more than 99.9% as shown by HPLC and TLC detection. With this procedure, ST was obtained at about one tenth of its commercial cost展开更多
We present results on approximate solutions to the biadditive equationf（x＋y,z-w）＋f（x-y,z＋w）=2f（x,z）-2f（y,w）on a restricted domain. The proof is based on a quite recent fixed point theorem in some function s...We present results on approximate solutions to the biadditive equationf（x＋y,z-w）＋f（x-y,z＋w）=2f（x,z）-2f（y,w）on a restricted domain. The proof is based on a quite recent fixed point theorem in some function spaces. Our main results state that, under some weak natural assumptions, functions satisfying the equation approximately （in some sense） must be actually solutions to it. In this way we obtain inequalities characterizing biadditive mappings and inner product spaces. Our outcomes are connected with the well known issues of Ulam stability and hyperstability.展开更多
文摘Fourteen strains of Aspergillus versicolor and 2 strains of A. nidulans were screened for sterigmatocystin (ST) production on a semi-synthetic solid substrate by high performence liquid chromatography (HPLC) analysis. Two strains of A. versicolor producing ST at 550.5 mg.kg-1 substrate and 1160.8 mg·kg-1 substrate were selected to inoculate 4 kg solid ST-producing media. After 30 days stationary incubation at 28 ℃ in the dark, 2271.6 mg of pale-yellow needle-shaped crystals were isolated and purified from the culture with a procedure applying column chromatography and recrystallization method. The crystal was proved to be sterigmatocystin by spectroanalysis and some physico-chemical analysis. The purity of the final material obtained were more than 99.9% as shown by HPLC and TLC detection. With this procedure, ST was obtained at about one tenth of its commercial cost
文摘We present results on approximate solutions to the biadditive equationf（x＋y,z-w）＋f（x-y,z＋w）=2f（x,z）-2f（y,w）on a restricted domain. The proof is based on a quite recent fixed point theorem in some function spaces. Our main results state that, under some weak natural assumptions, functions satisfying the equation approximately （in some sense） must be actually solutions to it. In this way we obtain inequalities characterizing biadditive mappings and inner product spaces. Our outcomes are connected with the well known issues of Ulam stability and hyperstability.
