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
To elucidate the effect of calcite-regulated activated carbon(AC)structure on low-temperature denitrification performance of SCR catalysts,this work prepared a series of Mn-Ce/De-AC-xCaCO_(3)(x is the calcite content ...To elucidate the effect of calcite-regulated activated carbon(AC)structure on low-temperature denitrification performance of SCR catalysts,this work prepared a series of Mn-Ce/De-AC-xCaCO_(3)(x is the calcite content in coal)catalysts were prepared by the incipient wetness impregnation method,followed by acid washing to remove calcium-containing minerals.Comprehensive characterization and low-temperature denitrification tests revealed that calcite-induced structural modulation of coal-derived AC significantly enhances catalytic activity.Specifically,NO conversion increased from 88.3%of Mn-Ce/De-AC to 91.7%of Mn-Ce/De-AC-1CaCO_(3)(210℃).The improved SCR denitrification activity results from the enhancement of physicochemical properties including higher Mn^(4+)content and Ce^(4+)/Ce^(3+)ratio,an abundance of chemisorbed oxygen and acidic sites,which could strengthen the SCR reaction pathways(richer NH_(3)activated species and bidentate nitrate active species).Therefore,NO removal is enhanced.展开更多
The Chang＇E-3 （CE-3） mission began with a smooth countdown and flawless launch on the Long March 3B rocket from the Xichang satellite launch center at 01：30 CST on December 2, 2013. It landed on the northeastern I...The Chang＇E-3 （CE-3） mission began with a smooth countdown and flawless launch on the Long March 3B rocket from the Xichang satellite launch center at 01：30 CST on December 2, 2013. It landed on the northeastern Imbrium basin （340.49°E, 44.12°N） at 21：11 CST on December 14, 2013, and the Yutu rover was deployed from the lander the next morning at 04：35.展开更多
In this paper, Ce_(0.2)Zr_(0.8)O_2 composite supports were prepared by different Ce-addition methods including impregnation of cerium(CeZr-imp), impregnation of citric acid and cerium(CeZr-CA) simultaneously and depos...In this paper, Ce_(0.2)Zr_(0.8)O_2 composite supports were prepared by different Ce-addition methods including impregnation of cerium(CeZr-imp), impregnation of citric acid and cerium(CeZr-CA) simultaneously and deposition precipitation method(CeZr-DP), respectively. The as-prepared supports were applied to prepare 10 wt% MoO_3/Ce_(0.2)Zr_(0.8)O_2 catalysts for sulfur-resistant methanation. The N_2 adsorption/desorption,X-ray diffraction(XRD), Raman spectroscopy(RS), X-ray photoelectron(XPS), temperature-programmed reduction by hydrogen(H_2-TPR) were undertaken to get textural properties, morphological information and structures of the catalysts. The results showed that Mo O_3 was highly dispersed on the surface of these three supports and Ce was mostly of coexisted in Ce^(4+)/Ce^(3+) redox pairs. Compared with Mo/CeZrimp, the CO conversion increased by 10% and 15% for Mo/CeZr-CA and Mo/CeZr-DP, respectively. This was mainly attributed to the larger specific surface area, Ce^(3+) concentration and content of active MoS_2 on the surface of catalysts.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。
基金Supported by the Science and Technology Cooperation and Exchange special project of Cooperation of Shanxi Province(202404041101014)the Fundamental Research Program of Shanxi Province(202403021212333)+3 种基金the Joint Funds of the National Natural Science Foundation of China(U24A20555)the Lvliang Key R&D of University-Local Cooperation(2023XDHZ10)the Initiation Fund for Doctoral Research of Taiyuan University of Science and Technology(20242026)the Outstanding Doctor Funding Award of Shanxi Province(20242080).
文摘To elucidate the effect of calcite-regulated activated carbon(AC)structure on low-temperature denitrification performance of SCR catalysts,this work prepared a series of Mn-Ce/De-AC-xCaCO_(3)(x is the calcite content in coal)catalysts were prepared by the incipient wetness impregnation method,followed by acid washing to remove calcium-containing minerals.Comprehensive characterization and low-temperature denitrification tests revealed that calcite-induced structural modulation of coal-derived AC significantly enhances catalytic activity.Specifically,NO conversion increased from 88.3%of Mn-Ce/De-AC to 91.7%of Mn-Ce/De-AC-1CaCO_(3)(210℃).The improved SCR denitrification activity results from the enhancement of physicochemical properties including higher Mn^(4+)content and Ce^(4+)/Ce^(3+)ratio,an abundance of chemisorbed oxygen and acidic sites,which could strengthen the SCR reaction pathways(richer NH_(3)activated species and bidentate nitrate active species).Therefore,NO removal is enhanced.
基金supported by the Major Program of the National Natural Science Foundation of China(Grant No.41590851)
文摘The Chang＇E-3 （CE-3） mission began with a smooth countdown and flawless launch on the Long March 3B rocket from the Xichang satellite launch center at 01：30 CST on December 2, 2013. It landed on the northeastern Imbrium basin （340.49°E, 44.12°N） at 21：11 CST on December 14, 2013, and the Yutu rover was deployed from the lander the next morning at 04：35.
基金Financial supports from the National High Technology Research and Development Program of China (863 Project) (2015AA050504)the National Natural Science Foundation of China (21576203)
文摘In this paper, Ce_(0.2)Zr_(0.8)O_2 composite supports were prepared by different Ce-addition methods including impregnation of cerium(CeZr-imp), impregnation of citric acid and cerium(CeZr-CA) simultaneously and deposition precipitation method(CeZr-DP), respectively. The as-prepared supports were applied to prepare 10 wt% MoO_3/Ce_(0.2)Zr_(0.8)O_2 catalysts for sulfur-resistant methanation. The N_2 adsorption/desorption,X-ray diffraction(XRD), Raman spectroscopy(RS), X-ray photoelectron(XPS), temperature-programmed reduction by hydrogen(H_2-TPR) were undertaken to get textural properties, morphological information and structures of the catalysts. The results showed that Mo O_3 was highly dispersed on the surface of these three supports and Ce was mostly of coexisted in Ce^(4+)/Ce^(3+) redox pairs. Compared with Mo/CeZrimp, the CO conversion increased by 10% and 15% for Mo/CeZr-CA and Mo/CeZr-DP, respectively. This was mainly attributed to the larger specific surface area, Ce^(3+) concentration and content of active MoS_2 on the surface of catalysts.
