The optimum concentration of Na_2 WO_4 was explored in relation to the cell density and astaxanthin content in Haematococcus pluvialis. Then, the cellular morphology, nitrate reductase(NR) activity, soluble sugar and ...The optimum concentration of Na_2 WO_4 was explored in relation to the cell density and astaxanthin content in Haematococcus pluvialis. Then, the cellular morphology, nitrate reductase(NR) activity, soluble sugar and protein contents, and chlorophyll ?uorescence were measured, and the transcriptional expression of carotenogenic genes was determined by quantitative real-time PCR. The results showed that 3.0 mmol/L of Na_2 WO_4 was the optimum concentration to induce astaxanthin accumulation, with a maximum content of 49.41±0.13 pg/cell reached on the tenth day. The NR activity decreased signi?cantly and continually after Na_2 WO_4 treatment. The soluble sugar content increased gradually during the experimental period and was eventually signi?cantly higher than that in the control. The soluble protein content increased rapidly,reached a maximum in day 0.5 and day 1 and then decreased. The ef fective photochemical effciency of PSII( F v'/F m') and light saturation( E k) ?rst decreased and then tended to stabilize, and NADP +-glyceraldehyde-3-phosphate dehydrogenase(GAPDH) gene expression was correlated with photosynthesis. The transcriptional expression of ipi, psy and bkt was signi?cantly increased compared with that in the control after application of Na_2 WO_4, and the relative expression of ipi reached the highest level on the ?fth day, with a 98.03±1.92-fold increase. Our results describe a new approach to promote the ef fective accumulation of astaxanthin in H. pluvialis by NR inhibitor Na_2 WO_4.展开更多
Selective coupling of methyl radicals to produce C_(2) species(C2H4 and C2H6)is a key challenge for oxidative coupling of methane(OCM).In traditional OCM reaction systems,homogeneous transformation of methyl radicals ...Selective coupling of methyl radicals to produce C_(2) species(C2H4 and C2H6)is a key challenge for oxidative coupling of methane(OCM).In traditional OCM reaction systems,homogeneous transformation of methyl radicals in O_(2)‐containing gases are uncontrollable,resulting in limited C_(2) selectivity and yield.Herein,we demonstrate that methyl radicals generated by La_(2)O_(3)at low reaction temperature can selectively couple on the surface of 5 wt%Na2WO4/SiO_(2).The controllable surface coupling against overoxidation barely changes the activity of La_(2)O_(3)but boosts the C_(2)selectivity by three times and achieves a C_(2)yield as high as 10.9%at bed temperature of only 570℃.Structure‐property studies suggest that Na_(2)WO_(4) nanoclusters are the active sites for methyl radical coupling.The strong CH_(3)·affinity of these sites can even endow some methane combustion catalysts with OCM activity.The findings of the surface coupling of methyl radicals open a new direction to develop OCM catalyst.The bifunctional OCM catalyst system,which composes of a methane activation center and a CH_(3)·coupling center,may deliver promising OCM performance at reaction temperatures below the ignition temperature of C2H6 and C2H4(~600℃)and is therefore more controllable,safer,and certainly more attractive as an actual process.展开更多
Oxidative desulfurization was performed on Na_(2)WO_(4)catalyst in the presence of hydrogen peroxide and acetic acid under mild reaction conditions(atmospheric pressure and temperature range of 293--343 K).Different o...Oxidative desulfurization was performed on Na_(2)WO_(4)catalyst in the presence of hydrogen peroxide and acetic acid under mild reaction conditions(atmospheric pressure and temperature range of 293--343 K).Different organic compounds including benzothiophene(BT),dibenzothiophene(DBT),4,6-dimethyl dibenzothiophene(4,6-DMDBT)were used to investigate the reactivity of this catalyst,and the effect of various parameters,such as temperature,solvents and the amount of oxidant reagent used in oxidative desulfurization reaction,was also examined.The results showed that the Na2WO4-H202 system was very effective for oxidative desulfurization,and the oxidation of BT,DBT and 4,6-DMDBT was influenced by different parameters.展开更多
基金Supported by the National Natural Science Foundation of China(No.31572638)the Public Benefit Program of Zhejiang Science and Technology Department(No.2015C32021)+4 种基金the Program of Ningbo Science and Technology Bureau(No.2014C10023)the NSF of Ningbo Government(No.2015A610265)the Project of Science and Technology Innovation for College Students in Zhejiang Province(No.2016R405078)the K.C.Wong Magna Fund in Ningbo Universitythe Subject Project of Ningbo University(No.xkl1526)
文摘The optimum concentration of Na_2 WO_4 was explored in relation to the cell density and astaxanthin content in Haematococcus pluvialis. Then, the cellular morphology, nitrate reductase(NR) activity, soluble sugar and protein contents, and chlorophyll ?uorescence were measured, and the transcriptional expression of carotenogenic genes was determined by quantitative real-time PCR. The results showed that 3.0 mmol/L of Na_2 WO_4 was the optimum concentration to induce astaxanthin accumulation, with a maximum content of 49.41±0.13 pg/cell reached on the tenth day. The NR activity decreased signi?cantly and continually after Na_2 WO_4 treatment. The soluble sugar content increased gradually during the experimental period and was eventually signi?cantly higher than that in the control. The soluble protein content increased rapidly,reached a maximum in day 0.5 and day 1 and then decreased. The ef fective photochemical effciency of PSII( F v'/F m') and light saturation( E k) ?rst decreased and then tended to stabilize, and NADP +-glyceraldehyde-3-phosphate dehydrogenase(GAPDH) gene expression was correlated with photosynthesis. The transcriptional expression of ipi, psy and bkt was signi?cantly increased compared with that in the control after application of Na_2 WO_4, and the relative expression of ipi reached the highest level on the ?fth day, with a 98.03±1.92-fold increase. Our results describe a new approach to promote the ef fective accumulation of astaxanthin in H. pluvialis by NR inhibitor Na_2 WO_4.
文摘Selective coupling of methyl radicals to produce C_(2) species(C2H4 and C2H6)is a key challenge for oxidative coupling of methane(OCM).In traditional OCM reaction systems,homogeneous transformation of methyl radicals in O_(2)‐containing gases are uncontrollable,resulting in limited C_(2) selectivity and yield.Herein,we demonstrate that methyl radicals generated by La_(2)O_(3)at low reaction temperature can selectively couple on the surface of 5 wt%Na2WO4/SiO_(2).The controllable surface coupling against overoxidation barely changes the activity of La_(2)O_(3)but boosts the C_(2)selectivity by three times and achieves a C_(2)yield as high as 10.9%at bed temperature of only 570℃.Structure‐property studies suggest that Na_(2)WO_(4) nanoclusters are the active sites for methyl radical coupling.The strong CH_(3)·affinity of these sites can even endow some methane combustion catalysts with OCM activity.The findings of the surface coupling of methyl radicals open a new direction to develop OCM catalyst.The bifunctional OCM catalyst system,which composes of a methane activation center and a CH_(3)·coupling center,may deliver promising OCM performance at reaction temperatures below the ignition temperature of C2H6 and C2H4(~600℃)and is therefore more controllable,safer,and certainly more attractive as an actual process.
文摘Oxidative desulfurization was performed on Na_(2)WO_(4)catalyst in the presence of hydrogen peroxide and acetic acid under mild reaction conditions(atmospheric pressure and temperature range of 293--343 K).Different organic compounds including benzothiophene(BT),dibenzothiophene(DBT),4,6-dimethyl dibenzothiophene(4,6-DMDBT)were used to investigate the reactivity of this catalyst,and the effect of various parameters,such as temperature,solvents and the amount of oxidant reagent used in oxidative desulfurization reaction,was also examined.The results showed that the Na2WO4-H202 system was very effective for oxidative desulfurization,and the oxidation of BT,DBT and 4,6-DMDBT was influenced by different parameters.
