Thermodynamic simulation was conducted to design a new process of stepwise precipitating NH_4VO_(3)and NaHCO_(3)from regulating the CO_(2)carbonation of Na_(3)VO_(4)solution.Firstly,a new V(V)speciation model for the ...Thermodynamic simulation was conducted to design a new process of stepwise precipitating NH_4VO_(3)and NaHCO_(3)from regulating the CO_(2)carbonation of Na_(3)VO_(4)solution.Firstly,a new V(V)speciation model for the aqueous solution containing vanadate and carbonate is established by using the Bromley-Zemaitis activity coefficient model.Subsequently,thermodynamic equilibrium calculations are conducted to clarify the behavior of vanadium,carbon,sodium,and impurity species in atmospheric or high-pressure carbonation.To ensure the purity and recovery of vanadium products,Na_(3)VO_(4)solution is initially carbonated to the pH of 9.3-9.4,followed by precipitating NH_4VO_(3)by adding(NH_4)_(2)CO_(3).After vanadium precipitation,the solution is deeply carbonated to the final pH of 7.3-7.5 to precipitate NaHCO_(3),and the remaining solution is recycled to dissolve Na_(3)VO_(4)crystals.Finally,verification experiments demonstrate that 99.1%of vanadium and 91.4%of sodium in the solution are recovered in the form of NH_4VO_(3)and NaHCO_(3),respectively.展开更多
目的:探讨离体家猪椎体模型松质骨在不同扫描条件下CT值与定量CT骨密度(BMD)的相关性。方法:自制离体猪脊柱标本体模,在7种不同扫描条件(管电压固定为120 k V,管电流与曝光时间的乘积200、150、100和50 m As;管电流与曝光时间的乘积固定...目的:探讨离体家猪椎体模型松质骨在不同扫描条件下CT值与定量CT骨密度(BMD)的相关性。方法:自制离体猪脊柱标本体模,在7种不同扫描条件(管电压固定为120 k V,管电流与曝光时间的乘积200、150、100和50 m As;管电流与曝光时间的乘积固定为200 m As,管电压140、120、100和80 k V)下,分别对家猪椎体松质骨进行两次CT扫描,分析改变管电流与曝光时间的乘积或管电压对CT值与BMD值的影响,并对CT值与BMD值进行相关性分析。结果:(1)管电流与曝光时间的乘积采用200 m As时,不同管电压(140、120、100和80 k V)下,CT值的差异具统计学意义(P<0.05),BMD值差异无统计学意义(P>0.05);(2)管电压采用120 k V时,不同管电流与曝光时间的乘积(200、150、100和50 m As)CT值和BMD值差异均无统计学意义(P>0.05);(3)7种不同扫描条件下,CT值与BMD值之间相关系数分别为r(200 m As,80 k V)=0.830,r(200 m As,100 k V)=0.961,r(200 m As,120 k V)=0.972,r(200 m As,140 k V)=0.711,r(120 k V,50 m As)=0.736,r(120 k V,100 m As)=0.873,r(120 k V,150 m As)=0.936,呈明显的线性正相关。结论:CT值与BMD值呈线性相关,在临床常规CT扫描条件(120 k V、200 m As)下相关系数最高,可用此时CT值评价成年人椎体骨密度情况。展开更多
基金the financial supports from the National Natural Science Foundation of China(No.22078343)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0430103)the National Key Research and Development Program of China(No.2018YFC1900502)。
文摘Thermodynamic simulation was conducted to design a new process of stepwise precipitating NH_4VO_(3)and NaHCO_(3)from regulating the CO_(2)carbonation of Na_(3)VO_(4)solution.Firstly,a new V(V)speciation model for the aqueous solution containing vanadate and carbonate is established by using the Bromley-Zemaitis activity coefficient model.Subsequently,thermodynamic equilibrium calculations are conducted to clarify the behavior of vanadium,carbon,sodium,and impurity species in atmospheric or high-pressure carbonation.To ensure the purity and recovery of vanadium products,Na_(3)VO_(4)solution is initially carbonated to the pH of 9.3-9.4,followed by precipitating NH_4VO_(3)by adding(NH_4)_(2)CO_(3).After vanadium precipitation,the solution is deeply carbonated to the final pH of 7.3-7.5 to precipitate NaHCO_(3),and the remaining solution is recycled to dissolve Na_(3)VO_(4)crystals.Finally,verification experiments demonstrate that 99.1%of vanadium and 91.4%of sodium in the solution are recovered in the form of NH_4VO_(3)and NaHCO_(3),respectively.
文摘目的:探讨离体家猪椎体模型松质骨在不同扫描条件下CT值与定量CT骨密度(BMD)的相关性。方法:自制离体猪脊柱标本体模,在7种不同扫描条件(管电压固定为120 k V,管电流与曝光时间的乘积200、150、100和50 m As;管电流与曝光时间的乘积固定为200 m As,管电压140、120、100和80 k V)下,分别对家猪椎体松质骨进行两次CT扫描,分析改变管电流与曝光时间的乘积或管电压对CT值与BMD值的影响,并对CT值与BMD值进行相关性分析。结果:(1)管电流与曝光时间的乘积采用200 m As时,不同管电压(140、120、100和80 k V)下,CT值的差异具统计学意义(P<0.05),BMD值差异无统计学意义(P>0.05);(2)管电压采用120 k V时,不同管电流与曝光时间的乘积(200、150、100和50 m As)CT值和BMD值差异均无统计学意义(P>0.05);(3)7种不同扫描条件下,CT值与BMD值之间相关系数分别为r(200 m As,80 k V)=0.830,r(200 m As,100 k V)=0.961,r(200 m As,120 k V)=0.972,r(200 m As,140 k V)=0.711,r(120 k V,50 m As)=0.736,r(120 k V,100 m As)=0.873,r(120 k V,150 m As)=0.936,呈明显的线性正相关。结论:CT值与BMD值呈线性相关,在临床常规CT扫描条件(120 k V、200 m As)下相关系数最高,可用此时CT值评价成年人椎体骨密度情况。
