Cellulase is an enzyme produced by fungi, bacteria, protozoa and termite, that hydrolyze cellulose. They are known for their diverse applications in industry and medicine. The aim of this study is to purify and invest...Cellulase is an enzyme produced by fungi, bacteria, protozoa and termite, that hydrolyze cellulose. They are known for their diverse applications in industry and medicine. The aim of this study is to purify and investigate cellulolytic properties of cellulase enzyme produced by Bacillus sphaericus CE-3 isolated from refuse dump in Nnamdi Azikiwe University, Awka, Nigeria. Enzyme was produced by submerged fermentation at 30°C for 30 h. The enzyme was purified to homogeneity by dialysis in 4M sucrose solution, ion-exchange chromatography on Q-Sepharose FF and by hydrophobic interaction chromatography on Phenyl Sepharose CL-4B. The relative molecular mass of the enzyme was estimated using SDS-Polyacrylamide gel electrophoresis. Effects of temperature, pH and metals on enzyme activity and stability and the relative rate of hydrolysis of various substrates were also studied. The Purification fold for the enzyme was 7.8, with 66.4 μ/mg specific activity protein and overall yield of 35.8. The relative molecular mass range of the enzyme was estimated between 22.3 kDa - 26.3 kDa. The enzyme was optimally active at pH 9.0 and 40°C, stable at pH 9.0 and unusually retained over 90% activity between 50°C - 100°C after 30 min incubation. It was strongly activated by Mn2+ but inhibited by Ba2+, Co2+, Hg2+, Pb2+, Cu2+, Sr2+, Fe2+, Ca2+ and Zn2+. The cellulase displayed high catalytic activity with untreated sawdust, followed by carboxymethyl cellulose, while sodium hydroxide treated sawdust was the least hydrolyzed. Since the enzyme is thermo-stable, alkalophilic and could utilize natural wastes like sawdust as substrate, it is obvious that it would be of great use in textile, starch processing and pulp and paper industries.展开更多
以硝酸铈和尿素为原料,1,3,5苯三甲酸为配体,采用简单的静电自组装法合成了铈金属有机框架(Ce-BTC)和石墨相氮化碳(g-C_(3)N_(4))的复合材料(Ce-BTC/g-C_(3)N_(4)),用于二氧化碳还原制一氧化碳的研究,并探索Ce-BTC的复合对g-C_(3)N_(4)...以硝酸铈和尿素为原料,1,3,5苯三甲酸为配体,采用简单的静电自组装法合成了铈金属有机框架(Ce-BTC)和石墨相氮化碳(g-C_(3)N_(4))的复合材料(Ce-BTC/g-C_(3)N_(4)),用于二氧化碳还原制一氧化碳的研究,并探索Ce-BTC的复合对g-C_(3)N_(4)性能的影响机制。利用X射线衍射、红外光谱、扫描电子显微镜、紫外-可见光吸收光谱、荧光光谱、阻抗、光电流测试和CO_(2)还原性能测试对复合材料的结构、形貌、光电学性能及催化性能进行研究。结果表明Ce-BTC与g-C_(3)N_(4)的复合可能使得g-C_(3)N_(4)层间距发生改变,在细化晶体颗粒的同时提高样品比表面积,使复合样品获得更高的可见光捕获能力且载流子的分离效率更高;在仅加入1 mL H2O作为质子提供源的前提下,Ce-BTC/g-C_(3)N_(4)-3拥有最优光催化性能。CO产率为19.02μmol/(h·g),是g-C_(3)N_(4)的2.25倍,循环测试后催化性能基本保持稳定。展开更多
采用高温固相法制备了SrZrSi_(2)O_(7):Ce^(3+),Mn^(2+)荧光粉。通过X射线衍射(X-ray Power Diffractometer,XRD)、激发和发射光谱及电子显微分析对材料的分子结构、显微形貌、发光特性和能量传递机理进行了研究。结果表明,荧光粉的主...采用高温固相法制备了SrZrSi_(2)O_(7):Ce^(3+),Mn^(2+)荧光粉。通过X射线衍射(X-ray Power Diffractometer,XRD)、激发和发射光谱及电子显微分析对材料的分子结构、显微形貌、发光特性和能量传递机理进行了研究。结果表明,荧光粉的主晶相是单斜晶系的SrZrSi_(2)O_(7),Ce^(3+)离子和Mn^(2+)离子占据一部分Sr^(2+)离子的晶体学格位。在296 nm激发下,可以观察到来自Ce^(3+)离子的蓝光发射峰,归属于Ce^(3+)离子的5d→4f能级跃迁。在544 nm处,有来自Mn^(2+)离子的绿光发射峰,归因于Mn^(2+)离子的^(4)T_(1)(4G)-^(6)A_(1)(6S)自旋禁止跃迁,表明发生了从Ce^(3+)离子到Mn^(2+)离子的能量传递过程,为设计蓝光到绿光之间可控制备的新型荧光粉提供了理论和实验的信息。展开更多
文摘Cellulase is an enzyme produced by fungi, bacteria, protozoa and termite, that hydrolyze cellulose. They are known for their diverse applications in industry and medicine. The aim of this study is to purify and investigate cellulolytic properties of cellulase enzyme produced by Bacillus sphaericus CE-3 isolated from refuse dump in Nnamdi Azikiwe University, Awka, Nigeria. Enzyme was produced by submerged fermentation at 30°C for 30 h. The enzyme was purified to homogeneity by dialysis in 4M sucrose solution, ion-exchange chromatography on Q-Sepharose FF and by hydrophobic interaction chromatography on Phenyl Sepharose CL-4B. The relative molecular mass of the enzyme was estimated using SDS-Polyacrylamide gel electrophoresis. Effects of temperature, pH and metals on enzyme activity and stability and the relative rate of hydrolysis of various substrates were also studied. The Purification fold for the enzyme was 7.8, with 66.4 μ/mg specific activity protein and overall yield of 35.8. The relative molecular mass range of the enzyme was estimated between 22.3 kDa - 26.3 kDa. The enzyme was optimally active at pH 9.0 and 40°C, stable at pH 9.0 and unusually retained over 90% activity between 50°C - 100°C after 30 min incubation. It was strongly activated by Mn2+ but inhibited by Ba2+, Co2+, Hg2+, Pb2+, Cu2+, Sr2+, Fe2+, Ca2+ and Zn2+. The cellulase displayed high catalytic activity with untreated sawdust, followed by carboxymethyl cellulose, while sodium hydroxide treated sawdust was the least hydrolyzed. Since the enzyme is thermo-stable, alkalophilic and could utilize natural wastes like sawdust as substrate, it is obvious that it would be of great use in textile, starch processing and pulp and paper industries.
文摘以硝酸铈和尿素为原料,1,3,5苯三甲酸为配体,采用简单的静电自组装法合成了铈金属有机框架(Ce-BTC)和石墨相氮化碳(g-C_(3)N_(4))的复合材料(Ce-BTC/g-C_(3)N_(4)),用于二氧化碳还原制一氧化碳的研究,并探索Ce-BTC的复合对g-C_(3)N_(4)性能的影响机制。利用X射线衍射、红外光谱、扫描电子显微镜、紫外-可见光吸收光谱、荧光光谱、阻抗、光电流测试和CO_(2)还原性能测试对复合材料的结构、形貌、光电学性能及催化性能进行研究。结果表明Ce-BTC与g-C_(3)N_(4)的复合可能使得g-C_(3)N_(4)层间距发生改变,在细化晶体颗粒的同时提高样品比表面积,使复合样品获得更高的可见光捕获能力且载流子的分离效率更高;在仅加入1 mL H2O作为质子提供源的前提下,Ce-BTC/g-C_(3)N_(4)-3拥有最优光催化性能。CO产率为19.02μmol/(h·g),是g-C_(3)N_(4)的2.25倍,循环测试后催化性能基本保持稳定。
文摘采用高温固相法制备了SrZrSi_(2)O_(7):Ce^(3+),Mn^(2+)荧光粉。通过X射线衍射(X-ray Power Diffractometer,XRD)、激发和发射光谱及电子显微分析对材料的分子结构、显微形貌、发光特性和能量传递机理进行了研究。结果表明,荧光粉的主晶相是单斜晶系的SrZrSi_(2)O_(7),Ce^(3+)离子和Mn^(2+)离子占据一部分Sr^(2+)离子的晶体学格位。在296 nm激发下,可以观察到来自Ce^(3+)离子的蓝光发射峰,归属于Ce^(3+)离子的5d→4f能级跃迁。在544 nm处,有来自Mn^(2+)离子的绿光发射峰,归因于Mn^(2+)离子的^(4)T_(1)(4G)-^(6)A_(1)(6S)自旋禁止跃迁,表明发生了从Ce^(3+)离子到Mn^(2+)离子的能量传递过程,为设计蓝光到绿光之间可控制备的新型荧光粉提供了理论和实验的信息。
