Filtration and cross-flow ultrafiltration techniques were used to separate culture media of Prorocentrum donghaiense at the exponential growth,stationary and decline stages into <0.45 μm filtrate,100 kDa-0.45 μm,...Filtration and cross-flow ultrafiltration techniques were used to separate culture media of Prorocentrum donghaiense at the exponential growth,stationary and decline stages into <0.45 μm filtrate,100 kDa-0.45 μm,10-100 kDa and 1-10 kDa retentate and <1 kDa ultrafiltrate fractions.The fluorescence properties of different molecular weights of dissolved organic matter(DOM) were measured by excitation-emission matrix spectra.Protein-like and humic-like fluorophores were observed in the DOM produced by P.donghaiense.The central positions of protein-like fluorophores showed a red shift with prolonged growth duration,shifting from tyrosine-like properties at the exponential growth stage to tryptophan-like properties at the stationary and decline stages.The excitation wavelengths of protein-like fluorophores exhibited some change in the exponential growth and stationary stages with increased molecular size,but showed little change in the decline stage.However,the emission wavelengths in the decline stage exhibited a blue shift.Very distinct C type and A type peaks in humic-like fluorophores were observed.With a prolonged culture time,the intensities of both of the peaks became strong and the excitation wavelengths of peak A showed a red shift,while the A:C ratios fell.More than 94% of fluorescent DOM was in the lower than 1 kDa molecular weight fraction.展开更多
The ground state structures of a series of organic molecules containing azo and/or oxadiazole units were obtained by means of density functional theory B3LYP/6-3IG（d） method. The first singlet excited state structur...The ground state structures of a series of organic molecules containing azo and/or oxadiazole units were obtained by means of density functional theory B3LYP/6-3IG（d） method. The first singlet excited state structures were optimized by virtue of singlet-excitation configuration interaction CIS/6-31G（d） method. The absorption and fluorescence emission spectra were then evaluated via the time-dependent density functional theory B3LYP and PBE1PBE methods with 6-31 l＋＋G（3df,2p） basis set. The calculation results show that compared with those of their parent molecules A-H, B-H, C-H, D-H, the absorption and emission wavelength values of all the derivatives show red shifts. The derivatives containing both the oxadiazole and methoxyl units are good candidates for longer absorption wavelength materials. The effects of azo, oxadiazole, and methoxyl units on the absorption and emission wavelength were discussed.展开更多
A series of aluminates were successfully synthesized via hydrothermal precipitated method, followed by solid state reaction at high temperature. The optimum condition to synthesize Sr3Al2O6 was determined by adjusting...A series of aluminates were successfully synthesized via hydrothermal precipitated method, followed by solid state reaction at high temperature. The optimum condition to synthesize Sr3Al2O6 was determined by adjusting the pH value of the solutions. The as prepared Sr3Al2O6 with lattice constant a=1.58556nm were characterized by X ray diffraction (XRD) and photoluminescence spectroscopy (PLS). In PL spectrum, a strongest peak at 655nm is observed, which is corresponding to red light, with an excitation wavelength of 459nm.展开更多
基金Supported by the High Technology Research and Development Program of China (863 Program) (Nos 2006AA09Z180 and 2004AA639790)the National Natural Science Foundation of China (No 40106013)the National Basic Research Program of China (973 Program) (No 2001CB409703)
文摘Filtration and cross-flow ultrafiltration techniques were used to separate culture media of Prorocentrum donghaiense at the exponential growth,stationary and decline stages into <0.45 μm filtrate,100 kDa-0.45 μm,10-100 kDa and 1-10 kDa retentate and <1 kDa ultrafiltrate fractions.The fluorescence properties of different molecular weights of dissolved organic matter(DOM) were measured by excitation-emission matrix spectra.Protein-like and humic-like fluorophores were observed in the DOM produced by P.donghaiense.The central positions of protein-like fluorophores showed a red shift with prolonged growth duration,shifting from tyrosine-like properties at the exponential growth stage to tryptophan-like properties at the stationary and decline stages.The excitation wavelengths of protein-like fluorophores exhibited some change in the exponential growth and stationary stages with increased molecular size,but showed little change in the decline stage.However,the emission wavelengths in the decline stage exhibited a blue shift.Very distinct C type and A type peaks in humic-like fluorophores were observed.With a prolonged culture time,the intensities of both of the peaks became strong and the excitation wavelengths of peak A showed a red shift,while the A:C ratios fell.More than 94% of fluorescent DOM was in the lower than 1 kDa molecular weight fraction.
基金Supported by the National Natural Science Foundation of China（Nos.21173109, 21133005）, the Specialized Research Fund for the Doctoral Program of Higher Education of China（No.20102136110001） and the Program for Liaoning Excellent Talents in University, China（No.LR2012037）.
文摘The ground state structures of a series of organic molecules containing azo and/or oxadiazole units were obtained by means of density functional theory B3LYP/6-3IG（d） method. The first singlet excited state structures were optimized by virtue of singlet-excitation configuration interaction CIS/6-31G（d） method. The absorption and fluorescence emission spectra were then evaluated via the time-dependent density functional theory B3LYP and PBE1PBE methods with 6-31 l＋＋G（3df,2p） basis set. The calculation results show that compared with those of their parent molecules A-H, B-H, C-H, D-H, the absorption and emission wavelength values of all the derivatives show red shifts. The derivatives containing both the oxadiazole and methoxyl units are good candidates for longer absorption wavelength materials. The effects of azo, oxadiazole, and methoxyl units on the absorption and emission wavelength were discussed.
文摘A series of aluminates were successfully synthesized via hydrothermal precipitated method, followed by solid state reaction at high temperature. The optimum condition to synthesize Sr3Al2O6 was determined by adjusting the pH value of the solutions. The as prepared Sr3Al2O6 with lattice constant a=1.58556nm were characterized by X ray diffraction (XRD) and photoluminescence spectroscopy (PLS). In PL spectrum, a strongest peak at 655nm is observed, which is corresponding to red light, with an excitation wavelength of 459nm.
