Zeolitic Imidazolate Framework-8(ZIF-8)material was prepared by chemical precipitation method.The microstructure and physical properties of the as-prepared samples were characterized by XRD,BET,FESEM and UV spectropho...Zeolitic Imidazolate Framework-8(ZIF-8)material was prepared by chemical precipitation method.The microstructure and physical properties of the as-prepared samples were characterized by XRD,BET,FESEM and UV spectrophotometer.The self-made four-channel measurement device was used to test the gas sensitivity of ZIF-8 material toward ethanol gas under photo-thermal synergistic excitation.The results showed that the sample was typical ZIF-8(E_(g)=4.96 eV)with a regular dodecahedron shape and the specific surface is up to 1793 m^(2)/g.The as-prepared ZIF-8 has a gas response value of 55.04 to 100 ppm ethanol at 75℃ and it shows good gas sensing selectivity and repeated stability.The excellent gas sensitivity can be attributed to the increase of free electron concentration in the ZIF-8 conduction band by photo-thermal synergistic excitation,and the large specific surface area of ZIF-8 material provides more active sites for gas-solid surface reaction.The reaction mechanism of ZIF-8 material under multi-field excitation was also discussed.展开更多
In this paper, the pointwise pseudo-orbit tracing property is defined on a compact metric space, and it is a generalization of pseudo-orbit tracing property. As applications, we prove the following results: (i) If / h...In this paper, the pointwise pseudo-orbit tracing property is defined on a compact metric space, and it is a generalization of pseudo-orbit tracing property. As applications, we prove the following results: (i) If / has pointwise pseudo-orbit tracing property, for any k ∈ Z+, and fk is chain transitive, then for any k ∈ Z+, fk has open set transitive ; (ii) If f has pointwise pseudo-orbit tracing property, and for any n ∈ Z+,fn is chain transitive, then f has sensitive dependence on initial conditions; (iii) If f is open set mixing and has pointwise pseudo-orbit tracing property, then f has property P; (iv) Let f : (X, d) →(X, d) be a homeomophism, then f is pointwise pseudo-orbit tracing property if and only if the shift map σf is pointwise pseudo-orbit tracing property.展开更多
Aiming at detecting Cl2 gas, this study was made on how to make In-based compound semiconductor oxide gas sensor. The micro-property and sensitivity of In-based gas sensing material were analyzed and its gas sensitive...Aiming at detecting Cl2 gas, this study was made on how to make In-based compound semiconductor oxide gas sensor. The micro-property and sensitivity of In-based gas sensing material were analyzed and its gas sensitive mechanism was also discussed. Adopting constant temperature chemical coprecipitation, the compound oxides such as In-Nb, In-Cd and In-Mg were synthesized, respectively. The products were sintered at 600 ℃ and characterized by the Scanning Electron Microscope （SEM）, showing the grain size almost about 50-60 nm. The test results show that the sensitivities of In-Nb, In-Cd and In-Mg materials under the concentration of 50 × 10^-6 in Cl2 gas are above 100 times, 4 times and 10 times, respectively. The response time of In-Nb, In-Cd and In-Mg materials is about 30, 60 and 30 s, and the recovery time less than 2, 10 and 2 min, respectively. Among them, the In-Nb material was found to have a relatively high conductivity and ideal sensitivity to Cl2 gas, which showed rather good selectivity and stability, and could detect the minimum concentration of 0.5 × 10^-6 with the sensitivity of 2.2, and the upper limit concentration of 500 × 10^-6. The power loss of the device is around 220 mW under the heating voltage of 3 V.展开更多
基金supported by the National Natural Science Foundation of China(No.51864028)the Yunnan Province Science and Technology Major Project for Materials Genetic Engineering of Rare and Precious Metal(No.202002AB080001)+2 种基金the Yunnan Province Funds for Distinguished Young Scientists,(No.2019FJ005)the Science Research Foundation of Yunnan Provincial Education Department(No.2022J0441)the Sichuan Science and Technology Program(No.22QYCX0097)。
文摘Zeolitic Imidazolate Framework-8(ZIF-8)material was prepared by chemical precipitation method.The microstructure and physical properties of the as-prepared samples were characterized by XRD,BET,FESEM and UV spectrophotometer.The self-made four-channel measurement device was used to test the gas sensitivity of ZIF-8 material toward ethanol gas under photo-thermal synergistic excitation.The results showed that the sample was typical ZIF-8(E_(g)=4.96 eV)with a regular dodecahedron shape and the specific surface is up to 1793 m^(2)/g.The as-prepared ZIF-8 has a gas response value of 55.04 to 100 ppm ethanol at 75℃ and it shows good gas sensing selectivity and repeated stability.The excellent gas sensitivity can be attributed to the increase of free electron concentration in the ZIF-8 conduction band by photo-thermal synergistic excitation,and the large specific surface area of ZIF-8 material provides more active sites for gas-solid surface reaction.The reaction mechanism of ZIF-8 material under multi-field excitation was also discussed.
文摘In this paper, the pointwise pseudo-orbit tracing property is defined on a compact metric space, and it is a generalization of pseudo-orbit tracing property. As applications, we prove the following results: (i) If / has pointwise pseudo-orbit tracing property, for any k ∈ Z+, and fk is chain transitive, then for any k ∈ Z+, fk has open set transitive ; (ii) If f has pointwise pseudo-orbit tracing property, and for any n ∈ Z+,fn is chain transitive, then f has sensitive dependence on initial conditions; (iii) If f is open set mixing and has pointwise pseudo-orbit tracing property, then f has property P; (iv) Let f : (X, d) →(X, d) be a homeomophism, then f is pointwise pseudo-orbit tracing property if and only if the shift map σf is pointwise pseudo-orbit tracing property.
基金supported by the National Natural Science Foundation of China (No. 60772019)the National High Technology Research andDevelopment Program of China (No. 2006AA040101-05)the National Science Foundation for Post-doctoral Scientists of China (No.20080440839).
文摘Aiming at detecting Cl2 gas, this study was made on how to make In-based compound semiconductor oxide gas sensor. The micro-property and sensitivity of In-based gas sensing material were analyzed and its gas sensitive mechanism was also discussed. Adopting constant temperature chemical coprecipitation, the compound oxides such as In-Nb, In-Cd and In-Mg were synthesized, respectively. The products were sintered at 600 ℃ and characterized by the Scanning Electron Microscope （SEM）, showing the grain size almost about 50-60 nm. The test results show that the sensitivities of In-Nb, In-Cd and In-Mg materials under the concentration of 50 × 10^-6 in Cl2 gas are above 100 times, 4 times and 10 times, respectively. The response time of In-Nb, In-Cd and In-Mg materials is about 30, 60 and 30 s, and the recovery time less than 2, 10 and 2 min, respectively. Among them, the In-Nb material was found to have a relatively high conductivity and ideal sensitivity to Cl2 gas, which showed rather good selectivity and stability, and could detect the minimum concentration of 0.5 × 10^-6 with the sensitivity of 2.2, and the upper limit concentration of 500 × 10^-6. The power loss of the device is around 220 mW under the heating voltage of 3 V.
