Selective reductive amination of carbonyl compounds with high activity is very essential for the chemical and pharmaceutical industry,but scarcely successful paradigm was reported via efficient photocatalytic reaction...Selective reductive amination of carbonyl compounds with high activity is very essential for the chemical and pharmaceutical industry,but scarcely successful paradigm was reported via efficient photocatalytic reactions.Herein,the ultrasmall Ru nanoclusters(~0.9 nm)were successfully fabricated over P25 support with positive charged Ru^(δ+)species at the interface.A new route was developed to achieve the furfural(FAL)to furfurylamine(FAM)by coupling the light-driven reductive amination and hydrogen transfer of ethanol over this type catalyst.Strikingly,the photocatalytic activity and selectivity are strongly dependent on the particle size and electronic structure of Ruthenium.The Ru^(δ+)species at the interface promote the formation of active imine intermediates;moreover,the Ru nanoclusters facilitate the separation efficiency of electrons and holes as well as accelerate the further hydrogenation of imine intermediates to product primary amines.In contrast Ru particles in larger nanometer size facilitate the formation of the furfuryl alcohol and excessive hydrogenation products.In addition,the coupling byproducts can be effectively inhibited via the construction of sub-nanocluster.This study offers a new path to produce the primary amines from biomass-derived carbonyl compounds over hybrid semiconductor/metal-clusters photocatalyst via light-driven tandem catalytic process.展开更多
Understanding bacterial adsorption and the evolution of biofilms on arsenopyrite with different surface structures is of great signific-ance to clarifying the mechanism of microbe-mineral interfacial interactions and ...Understanding bacterial adsorption and the evolution of biofilms on arsenopyrite with different surface structures is of great signific-ance to clarifying the mechanism of microbe-mineral interfacial interactions and the production of acidic mine drainage impacting the environ-ment.In this study,the attachment of Sulfobacillus thermosulfidooxidans cells and subsequent biofilm formation on arsenopyrite with different surface structures in the presence of dissolved As(Ⅲ)was studied.Arsenopyrite slices with a specific surface were obtained by electrochemic-al corrosion at 0.26 V.The scanning electronic microscopy-energy dispersion spectra analyses indicated that the arsenopyrite surface deficient in sulfur and iron obtained by electrochemical treatment was not favorable for the initial adsorption of bacteria,and the addition of As(Ⅲ)in-hibited the adsorption of microbial cells.Epifluorescence microscopy showed that the number of cells attaching to the arsenopyrite surface in-creased with time;however,biofilm formation was delayed significantly when As(Ⅲ)was added.展开更多
无线传感器网络(wireless sensor networks,WSNs)已经广泛应用于各个领域。许多领域利用了周期性数据汇聚,传感器节点周期性地产生数据包,通过一系列中继节点传输到汇聚节点。提出了一种分布式的基于预留的多信道MAC协议,称为R-MMAC协议...无线传感器网络(wireless sensor networks,WSNs)已经广泛应用于各个领域。许多领域利用了周期性数据汇聚,传感器节点周期性地产生数据包,通过一系列中继节点传输到汇聚节点。提出了一种分布式的基于预留的多信道MAC协议,称为R-MMAC协议,其中利用了预留机制和多信道通信机制,在多信道条件下,每个节点传输数据包时都将预留下一个数据包的传输,根据接收信号强度指示(received signal strength indication,RSSI)值选择自己的最佳信道进行预留。另外,还提出了针对预留时发生冲突的解决算法,利用信干噪比(signal to interference and noise ratio,SINR)和数据包接收率(packet reception rate,PRR)得到了预留的传输时间,从而降低了传感器节点到汇聚节点的传输时延和未来数据包的冲突概率。利用OMNET++5.3仿真工具对R-MMAC协议、X-MAC和EM-MAC协议进行了比较,结果表明R-MMAC协议实现了更低的端到端时延。展开更多
Promoting direct policy communication between policy makers and the public is both an important function of government annual reports (GARs) and a key issue in democratic politics.According to this survey,conducted in...Promoting direct policy communication between policy makers and the public is both an important function of government annual reports (GARs) and a key issue in democratic politics.According to this survey,conducted in 19 major cities in China,to promote the policy communication function of the GARs the government should make full use of changes in public policy communication habits and the convergence of public policy preferences in different groups while dealing with routine problems such as “public opinion deficits” and “being popular among the institutional staff but unnoticed the non-institutional staff.”展开更多
Thermal decomposition of inorganic metal carbonates is the main path to prepare metal oxides;nonetheless,it is always accompanied by the emission of large amounts of CO_(2) as one of the gas products.This study report...Thermal decomposition of inorganic metal carbonates is the main path to prepare metal oxides;nonetheless,it is always accompanied by the emission of large amounts of CO_(2) as one of the gas products.This study reports a concept of co-thermal insitu reduction of inorganic carbonates by using the energy released by carbonate decomposition under pure hydrogen atmosphere,which reduces the decarboxylation temperature and significantly inhibits the CO_(2) emissions.A combination of hydrogen–deuterium exchange,isotope experiment,and density functional theory calculations demonstrates that the CO results from the selective cleavage of Ca–O bonds at the surface of CaCO_(3) via the direct hydrogenation mechanism at relatively low temperature.However,it undergoes the reverse water–gas shift reaction path at high temperature,i.e.,CO being produced by the reduction of CO_(2) released by the decomposition of carbonates.This study sheds light on the potential of green hydrogen technology for inorganic carbonate valorization toward high value-added products,which can facilitate the large-scale industrial applications.展开更多
By combining trans-4-styrylprydine (tsp) with azide system, we obtained two rare 1D cis-EE-azido-bridged compounds of [M2(N3)4(tsp)4(H2O)2] [M = Mn (1), Co (2)]. The magnetic study reveals that metal ions are anti-fer...By combining trans-4-styrylprydine (tsp) with azide system, we obtained two rare 1D cis-EE-azido-bridged compounds of [M2(N3)4(tsp)4(H2O)2] [M = Mn (1), Co (2)]. The magnetic study reveals that metal ions are anti-ferromagnetically coupled by cis-EE-azido-bridges and they show weak ferromagnetism below 4.0 K (1) and 4.2 K (2) due to the spin-canting caused by asymmetric magnetic interaction.展开更多
By combining trans-4-styrylprydine (tsp) with azide system, we obtained two rare 1D cis-EE-azido-bridged compounds of [Mz(N3)4(tsp)4(H2O)2] [M = Mn (1), Co (2)]. The magnetic study reveals that metal ions ...By combining trans-4-styrylprydine (tsp) with azide system, we obtained two rare 1D cis-EE-azido-bridged compounds of [Mz(N3)4(tsp)4(H2O)2] [M = Mn (1), Co (2)]. The magnetic study reveals that metal ions are anti-ferromagnetically coupled by cis-EE-azido-bridges and they show weak ferromagnetism below 4.0 K (1) and 4.2 K (2) due to the spin-canting caused by asymmetric magnetic interaction.展开更多
基金financially supported by the National Natural Science Foundation of China(202102007,21978147 and 21935001)the Fundamental Research Funds for the Central Universities(buctrc202112)。
文摘Selective reductive amination of carbonyl compounds with high activity is very essential for the chemical and pharmaceutical industry,but scarcely successful paradigm was reported via efficient photocatalytic reactions.Herein,the ultrasmall Ru nanoclusters(~0.9 nm)were successfully fabricated over P25 support with positive charged Ru^(δ+)species at the interface.A new route was developed to achieve the furfural(FAL)to furfurylamine(FAM)by coupling the light-driven reductive amination and hydrogen transfer of ethanol over this type catalyst.Strikingly,the photocatalytic activity and selectivity are strongly dependent on the particle size and electronic structure of Ruthenium.The Ru^(δ+)species at the interface promote the formation of active imine intermediates;moreover,the Ru nanoclusters facilitate the separation efficiency of electrons and holes as well as accelerate the further hydrogenation of imine intermediates to product primary amines.In contrast Ru particles in larger nanometer size facilitate the formation of the furfuryl alcohol and excessive hydrogenation products.In addition,the coupling byproducts can be effectively inhibited via the construction of sub-nanocluster.This study offers a new path to produce the primary amines from biomass-derived carbonyl compounds over hybrid semiconductor/metal-clusters photocatalyst via light-driven tandem catalytic process.
基金This work was financially supported by National Natural Science Foundation of China(Nos.51774342,41802038,U1608254,51861135305,and 41830318)Beijing Syn-chrotron Radiation Facility Public User Program(2018-BEPC-PT-002240).
文摘Understanding bacterial adsorption and the evolution of biofilms on arsenopyrite with different surface structures is of great signific-ance to clarifying the mechanism of microbe-mineral interfacial interactions and the production of acidic mine drainage impacting the environ-ment.In this study,the attachment of Sulfobacillus thermosulfidooxidans cells and subsequent biofilm formation on arsenopyrite with different surface structures in the presence of dissolved As(Ⅲ)was studied.Arsenopyrite slices with a specific surface were obtained by electrochemic-al corrosion at 0.26 V.The scanning electronic microscopy-energy dispersion spectra analyses indicated that the arsenopyrite surface deficient in sulfur and iron obtained by electrochemical treatment was not favorable for the initial adsorption of bacteria,and the addition of As(Ⅲ)in-hibited the adsorption of microbial cells.Epifluorescence microscopy showed that the number of cells attaching to the arsenopyrite surface in-creased with time;however,biofilm formation was delayed significantly when As(Ⅲ)was added.
文摘无线传感器网络(wireless sensor networks,WSNs)已经广泛应用于各个领域。许多领域利用了周期性数据汇聚,传感器节点周期性地产生数据包,通过一系列中继节点传输到汇聚节点。提出了一种分布式的基于预留的多信道MAC协议,称为R-MMAC协议,其中利用了预留机制和多信道通信机制,在多信道条件下,每个节点传输数据包时都将预留下一个数据包的传输,根据接收信号强度指示(received signal strength indication,RSSI)值选择自己的最佳信道进行预留。另外,还提出了针对预留时发生冲突的解决算法,利用信干噪比(signal to interference and noise ratio,SINR)和数据包接收率(packet reception rate,PRR)得到了预留的传输时间,从而降低了传感器节点到汇聚节点的传输时延和未来数据包的冲突概率。利用OMNET++5.3仿真工具对R-MMAC协议、X-MAC和EM-MAC协议进行了比较,结果表明R-MMAC协议实现了更低的端到端时延。
基金sponsored by “Study on Policy Commitment,Information Disclosure and Signal Transmission Effects of Government Annual Reports”(14BGL116),a project of the National Social Science Fund of Chinaby the “special fund for basic scientific research of Jinan University”(15JNZK002)
文摘Promoting direct policy communication between policy makers and the public is both an important function of government annual reports (GARs) and a key issue in democratic politics.According to this survey,conducted in 19 major cities in China,to promote the policy communication function of the GARs the government should make full use of changes in public policy communication habits and the convergence of public policy preferences in different groups while dealing with routine problems such as “public opinion deficits” and “being popular among the institutional staff but unnoticed the non-institutional staff.”
基金supported by the National Natural Science Foundation of China(21922501,21871021,22102007)the Fundamental Research Funds for the Central Universities(buctrc202112)。
文摘Thermal decomposition of inorganic metal carbonates is the main path to prepare metal oxides;nonetheless,it is always accompanied by the emission of large amounts of CO_(2) as one of the gas products.This study reports a concept of co-thermal insitu reduction of inorganic carbonates by using the energy released by carbonate decomposition under pure hydrogen atmosphere,which reduces the decarboxylation temperature and significantly inhibits the CO_(2) emissions.A combination of hydrogen–deuterium exchange,isotope experiment,and density functional theory calculations demonstrates that the CO results from the selective cleavage of Ca–O bonds at the surface of CaCO_(3) via the direct hydrogenation mechanism at relatively low temperature.However,it undergoes the reverse water–gas shift reaction path at high temperature,i.e.,CO being produced by the reduction of CO_(2) released by the decomposition of carbonates.This study sheds light on the potential of green hydrogen technology for inorganic carbonate valorization toward high value-added products,which can facilitate the large-scale industrial applications.
文摘By combining trans-4-styrylprydine (tsp) with azide system, we obtained two rare 1D cis-EE-azido-bridged compounds of [M2(N3)4(tsp)4(H2O)2] [M = Mn (1), Co (2)]. The magnetic study reveals that metal ions are anti-ferromagnetically coupled by cis-EE-azido-bridges and they show weak ferromagnetism below 4.0 K (1) and 4.2 K (2) due to the spin-canting caused by asymmetric magnetic interaction.
基金financially supported by the National Natural Science Foundation of China (20801006, 21171023)
文摘By combining trans-4-styrylprydine (tsp) with azide system, we obtained two rare 1D cis-EE-azido-bridged compounds of [Mz(N3)4(tsp)4(H2O)2] [M = Mn (1), Co (2)]. The magnetic study reveals that metal ions are anti-ferromagnetically coupled by cis-EE-azido-bridges and they show weak ferromagnetism below 4.0 K (1) and 4.2 K (2) due to the spin-canting caused by asymmetric magnetic interaction.