Security schemes of pairwise key establishment, which enable sensors to communicate with each other se-curely, play a fundamental role in research on security issue in wireless sensor networks. A general frame-work fo...Security schemes of pairwise key establishment, which enable sensors to communicate with each other se-curely, play a fundamental role in research on security issue in wireless sensor networks. A general frame-work for key predistribution is presented, based on the idea of KDC (Key Distribution Center) and polyno-mial pool schemes. By utilizing nice properties of H2 (Hierarchical Hypercube) model, a new security mechanism for key predistribution based on such model is also proposed. Furthermore, the working per-formance of tolerance resistance is seriously inspected in this paper. Theoretic analysis and experimental fig-ures show that the algorithm addressed in this paper has better performance and provides higher possibilities for sensor to establish pairwise key, compared with previous related works.展开更多
Metal-organic frameworks （MOFs） are self-assembled molecular containers that can encapsulate and stabilize short-lived reaction intermediates. In this study, the Cu-benzene-l,3,5-tricarboxylate （BTC） MOF was incor...Metal-organic frameworks （MOFs） are self-assembled molecular containers that can encapsulate and stabilize short-lived reaction intermediates. In this study, the Cu-benzene-l,3,5-tricarboxylate （BTC） MOF was incorporated in a ZnO/graphene oxide （GO） photocatalytic system by electrostatic interaction, and the obtained assembly showed improved hydrogen evolution activity. Electron spin resonance analysis was used to detect and monitor free radicals in the photocatalytic system, and demonstrated that Cu-BTC MOF could stabilize and extend the lifetime of free radicals, increasing the chance of H. radical recombination to form H2. This work provides a new strategy for designing highly efficient photocatalysts.展开更多
In this work,a metal-organic frameworks material MIL-88 was prepared easily using solvent-thermal method,and was first found to have catalytic activities similar to those of biological enzymes such as catalase and per...In this work,a metal-organic frameworks material MIL-88 was prepared easily using solvent-thermal method,and was first found to have catalytic activities similar to those of biological enzymes such as catalase and peroxidase.The material was characterized by XRD,SEM,TEM,EDX,FT-IR techniques and an N2 adsorption method.It exhibited peroxidase-like activity through catalytic oxidation of the peroxidase substrate 3,3＇,5,5＇-tetramethylbenzidine（TMB） in the presence of H2O2,producing a blue-colored solution.Under optimal conditions,the absorbance at 652 nm is linearly correlated with the concentration of H2O2 from 2.0×10^-6 mol/L to 2.03×10^-5 mol/L（R-2=0.981） with a detection limit of 5.62×10^-7 mol/L（S/N=3）.More importantly,a sensitive and selective method for ascorbic acid detection was developed using this material as a catalyst.The analytical method for ascorbic acid detection was observed to have a linear range from 2.57×10^-6 mol/L to 1.01×10^-5 mol/L（R-2=0.989） with a detection limit of 1.03×10^-6 mol/L（S/N=3）.This work suggests MOFs have advantages of preparing biomimetic catalysts and extends applications of the functional MOFs in the field of biosensor.展开更多
Covalent organic frameworks(COFs) have recently emerged as a new class of photocatalysts.However,integrated design is crucial to maximizing the performance of COF-incorporating photocatalytic systems.Herein,we compare...Covalent organic frameworks(COFs) have recently emerged as a new class of photocatalysts.However,integrated design is crucial to maximizing the performance of COF-incorporating photocatalytic systems.Herein,we compare two strategies of installing earth-abundant metal-based catalytic centers into the matrice of a 2 D COF named NUS-55.Compared to NUS-55(Co)prepared from the post-synthetic metalation of coordination sites within the COF,the molecular co-catalyst impregnated NUS-55/[Co(bpy)3]Cl2 achieves a seven-fold improvement in visible light-driven H2 evolution rate to 2,480 μmol g^-1h^-1,with an apparent quantum efficiency(AQE) of 1.55% at 450 nm.Our results show that the rational design of molecular anchoring sites in COFs for the introduction of catalytic metal sites can be a viable strategy for the development of highly efficient photocatalysts with enhanced stability and photocatalytic activities.展开更多
采用分子模拟高通量筛选的方法研究了6013种实验已经合成的金属-有机框架(MOFs)对天然气五元混合物(CH_4,C_2H_6,C_3H_8,H_2S和CO_2)中H_2S和CO_2的吸附分离性能.为了综合吸附量和选择性这两项指标,我们首先比较了三种权衡方法[权衡α法...采用分子模拟高通量筛选的方法研究了6013种实验已经合成的金属-有机框架(MOFs)对天然气五元混合物(CH_4,C_2H_6,C_3H_8,H_2S和CO_2)中H_2S和CO_2的吸附分离性能.为了综合吸附量和选择性这两项指标,我们首先比较了三种权衡方法[权衡α法(Tradeoff between S_(H_2S+CO_2/C1-C3_ and N_(H_2S+CO_2), TSN),标准值法(Standard normal method, SNM)和权衡β法(Tradeoff between selectivity and capacity, TSC)].接着,针对四种MOF描述符[最大孔径(LCD),孔隙率(φ),比表面积(VSA)和吸附热(Q_(st)~0)],通过Pearson相关系数分析了每种描述符分别对三种权衡变量的相关性,结果显示TSC法与四种MOF描述符的相关性最佳.然后,使用多元线性回归方法定量地分析了四种MOF描述符分别对TSC的影响程度;而决策树模型则被用于规划性能高效MOFs的设计路径.最后, 20种性能最优MOFs从数据库中脱颖而出,它们将为净化天然气技术的发展提供坚实的理论指导.展开更多
文摘Security schemes of pairwise key establishment, which enable sensors to communicate with each other se-curely, play a fundamental role in research on security issue in wireless sensor networks. A general frame-work for key predistribution is presented, based on the idea of KDC (Key Distribution Center) and polyno-mial pool schemes. By utilizing nice properties of H2 (Hierarchical Hypercube) model, a new security mechanism for key predistribution based on such model is also proposed. Furthermore, the working per-formance of tolerance resistance is seriously inspected in this paper. Theoretic analysis and experimental fig-ures show that the algorithm addressed in this paper has better performance and provides higher possibilities for sensor to establish pairwise key, compared with previous related works.
文摘Metal-organic frameworks （MOFs） are self-assembled molecular containers that can encapsulate and stabilize short-lived reaction intermediates. In this study, the Cu-benzene-l,3,5-tricarboxylate （BTC） MOF was incorporated in a ZnO/graphene oxide （GO） photocatalytic system by electrostatic interaction, and the obtained assembly showed improved hydrogen evolution activity. Electron spin resonance analysis was used to detect and monitor free radicals in the photocatalytic system, and demonstrated that Cu-BTC MOF could stabilize and extend the lifetime of free radicals, increasing the chance of H. radical recombination to form H2. This work provides a new strategy for designing highly efficient photocatalysts.
基金the support of the Funds for Distinguished Young Scientists of Gansu(No.1506RJDA281)the top priority program of "One-Three-Five" Strategic Planning of Lanzhou Institute of Chemical Physics,CASthe Foundation for Sci&Tech Research Project of Gansu Province(No.1606RJYA307)
文摘In this work,a metal-organic frameworks material MIL-88 was prepared easily using solvent-thermal method,and was first found to have catalytic activities similar to those of biological enzymes such as catalase and peroxidase.The material was characterized by XRD,SEM,TEM,EDX,FT-IR techniques and an N2 adsorption method.It exhibited peroxidase-like activity through catalytic oxidation of the peroxidase substrate 3,3＇,5,5＇-tetramethylbenzidine（TMB） in the presence of H2O2,producing a blue-colored solution.Under optimal conditions,the absorbance at 652 nm is linearly correlated with the concentration of H2O2 from 2.0×10^-6 mol/L to 2.03×10^-5 mol/L（R-2=0.981） with a detection limit of 5.62×10^-7 mol/L（S/N=3）.More importantly,a sensitive and selective method for ascorbic acid detection was developed using this material as a catalyst.The analytical method for ascorbic acid detection was observed to have a linear range from 2.57×10^-6 mol/L to 1.01×10^-5 mol/L（R-2=0.989） with a detection limit of 1.03×10^-6 mol/L（S/N=3）.This work suggests MOFs have advantages of preparing biomimetic catalysts and extends applications of the functional MOFs in the field of biosensor.
基金supported by the National Research Foundation of Singapore(NRF2018-NRF-ANR007 POCEMON)the Ministry of Education-Singapore(MOE AcRF Tier 1 R-279-000-540-114,Tier 2 MOE2018-T2-2-148)+1 种基金the Agency for Science,Technology and Research(IRG A1783c0015,IAF-PP A1789a0024)the Jiangsu Overseas Visiting Scholar Program for University Prominent Young&Middle-Aged Teachers and Presidents
文摘Covalent organic frameworks(COFs) have recently emerged as a new class of photocatalysts.However,integrated design is crucial to maximizing the performance of COF-incorporating photocatalytic systems.Herein,we compare two strategies of installing earth-abundant metal-based catalytic centers into the matrice of a 2 D COF named NUS-55.Compared to NUS-55(Co)prepared from the post-synthetic metalation of coordination sites within the COF,the molecular co-catalyst impregnated NUS-55/[Co(bpy)3]Cl2 achieves a seven-fold improvement in visible light-driven H2 evolution rate to 2,480 μmol g^-1h^-1,with an apparent quantum efficiency(AQE) of 1.55% at 450 nm.Our results show that the rational design of molecular anchoring sites in COFs for the introduction of catalytic metal sites can be a viable strategy for the development of highly efficient photocatalysts with enhanced stability and photocatalytic activities.
基金This work is supported by the National Natural Science Foundation of China (Nos.21133001 and 21303004),and the National Basic Research Program of China (Nos.2013CB932601 and 2014CB239303).
文摘采用分子模拟高通量筛选的方法研究了6013种实验已经合成的金属-有机框架(MOFs)对天然气五元混合物(CH_4,C_2H_6,C_3H_8,H_2S和CO_2)中H_2S和CO_2的吸附分离性能.为了综合吸附量和选择性这两项指标,我们首先比较了三种权衡方法[权衡α法(Tradeoff between S_(H_2S+CO_2/C1-C3_ and N_(H_2S+CO_2), TSN),标准值法(Standard normal method, SNM)和权衡β法(Tradeoff between selectivity and capacity, TSC)].接着,针对四种MOF描述符[最大孔径(LCD),孔隙率(φ),比表面积(VSA)和吸附热(Q_(st)~0)],通过Pearson相关系数分析了每种描述符分别对三种权衡变量的相关性,结果显示TSC法与四种MOF描述符的相关性最佳.然后,使用多元线性回归方法定量地分析了四种MOF描述符分别对TSC的影响程度;而决策树模型则被用于规划性能高效MOFs的设计路径.最后, 20种性能最优MOFs从数据库中脱颖而出,它们将为净化天然气技术的发展提供坚实的理论指导.
