Aligned graphene nanoribbon (GNR) arrays have been made by unzipping of aligned single-walled and few-walled carbon nanotube (CNT) arrays. Nanotube unzipping was achieved by a polymer-protected Ar plasma etching metho...Aligned graphene nanoribbon (GNR) arrays have been made by unzipping of aligned single-walled and few-walled carbon nanotube (CNT) arrays. Nanotube unzipping was achieved by a polymer-protected Ar plasma etching method, and the resulting nanoribbon array can be transferred onto any chosen substrate. Atomic force microscope (AFM) imaging and Raman mapping on the same CNTs before and after unzipping confirmed that ~80% of CNTs were opened up to form single layer sub-10 nm GNRs. Electrical devices made from the GNRs (after annealing in H2 at high temperature) showed on/off current (Ion/Ioff) ratios up to 103 at room temperature, suggesting the semiconducting nature of the narrow GNRs. Novel GNR-GNR and GNR-CNT crossbars were fabricated by transferring GNR arrays across GNR and CNT arrays, respectively. The production of such ordered graphene nanoribbon architectures may allow for large scale integration of GNRs into nanoelectronics or optoelectronics.展开更多
Lithium-fluorinated carbon(Li-CFx)batteries have become one of the most widely applied power sources for high energy density applications because of the advantages provided by the CFx cathode.Moreover,the large gap be...Lithium-fluorinated carbon(Li-CFx)batteries have become one of the most widely applied power sources for high energy density applications because of the advantages provided by the CFx cathode.Moreover,the large gap between the practical and theoretical potentials alongside the stoichiometric limit of commercial graphite fluorides indicates the potential for further energy improvement.Herein,monolayer fluorinated graphene nanoribbons(F-GNRs)were fabricated by unzipping single-walled carbon nanotubes(SWCNTs)using pure F2 gas at high temperature,which delivered an unprecedented energy density of 2738.45 W h kg^(−1)due to the combined effect of a high fluorination degree and discharge plateau,realized by the abundant edges and destroyed periodic structure,respectively.Furthermore,at a high fluorination temperature,the theoretical calculation confirmed a zigzag pathway of fluorine atoms that were adsorbed outside of the SWCNTs and hence initiated the spontaneous process of unzipping SWCNTs to form the monolayer F-GNRs.The controllable fluorination of SWCNTs provided a feasible approach for preparing CFx compounds for different applications,especially for ultrahigh-energy-density cathodes.展开更多
This study investigates strategies for solving the system reliability of large three-dimensional jacket structures.These structural systems normally fail as a result of a series of different components failures.The fa...This study investigates strategies for solving the system reliability of large three-dimensional jacket structures.These structural systems normally fail as a result of a series of different components failures.The failure characteristics are investigated under various environmental conditions and direction combinations.Theβ-unzipping technique is adopted to determine critical failure components,and the entire system is simplified as a series-parallel system to approximately evaluate the structural system reliability.However,this approach needs excessive computational effort for searching failure components and failure paths.Based on a trained artificial neural network(ANN),which can be used to approximate the implicit limit-state function of a complicated structure,a new alternative procedure is proposed to improve the efficiency of the system reliability analysis method.The failure probability is calculated through Monte Carlo simulation(MCS)with Latin hypercube sampling(LHS).The features and applicability of the above procedure are discussed and compared using an example jacket platform located in Chengdao Oilfield,Bohai Sea,China.This study provides a reference for the evaluation of the system reliability of jacket structures.展开更多
商业化的多壁碳纳米管通常是相互缠绕且紧密团聚,长度高达数十微米,不利于电解液离子的传输,尤其是难以利用碳纳米管内部空间。本文通过简单的化学氧化方法从横向和纵向同时裁剪多壁碳纳米管,形成弯曲的石墨烯带(CGS),将其浸入0.1 mol L...商业化的多壁碳纳米管通常是相互缠绕且紧密团聚,长度高达数十微米,不利于电解液离子的传输,尤其是难以利用碳纳米管内部空间。本文通过简单的化学氧化方法从横向和纵向同时裁剪多壁碳纳米管,形成弯曲的石墨烯带(CGS),将其浸入0.1 mol L^(-1)高锰酸钾溶液中,合成了CGS-MnO_(2)复合材料。利用FESEM、TEM、XRD、Raman对CGS-MnO_(2)的形貌和结构进行详细表征,结果表明无定形MnO_(2)成功地锚定在CGS的表面。在三电极体系中,CGS-MnO_(2)在2 mV s^(-1)的扫速下电容值达到236 F g^(-1),甚至在100 mV s^(-1)下电容仍能保持127 F g^(-1),远高于对比样品的电容值,例如MWCNTs(15 F g^(-1)),CGS(88 F g^(-1))和MWCNTs-MnO_(2)复合材料(111 F g^(-1))。此外,该材料还表现出优异的循环稳定性能,循环1000次后电容仍然保持97%。展开更多
Hepatitis C virus(HCV)helicase is a molecular motor that splits nucleic acid duplex structures during viral replication,therefore representing a promising target for antiviral treatment.Hence,a detailed understanding ...Hepatitis C virus(HCV)helicase is a molecular motor that splits nucleic acid duplex structures during viral replication,therefore representing a promising target for antiviral treatment.Hence,a detailed understanding of the mechanism by which it operates would facilitate the development of efficient drug-assisted therapies aiming to inhibit helicase activity.Despite extensive investigations performed in the past,a thorough understanding of the activity of this important protein was lacking since the underlying internal conformational motions could not be resolved.Here we review investigations that have been previously performed by us for HCV helicase.Using methods of structure-based computational modelling it became possible to follow entire operation cycles of this motor protein in structurally resolved simulations and uncover the mechanism by which it moves along the nucleic acid and accomplishes strand separation.We also discuss observations from that study in the light of recent experimental studies that confirm our findings.展开更多
基金This work was supported by MARCO-MSD,Intel,ONR and graphene-MURI.
文摘Aligned graphene nanoribbon (GNR) arrays have been made by unzipping of aligned single-walled and few-walled carbon nanotube (CNT) arrays. Nanotube unzipping was achieved by a polymer-protected Ar plasma etching method, and the resulting nanoribbon array can be transferred onto any chosen substrate. Atomic force microscope (AFM) imaging and Raman mapping on the same CNTs before and after unzipping confirmed that ~80% of CNTs were opened up to form single layer sub-10 nm GNRs. Electrical devices made from the GNRs (after annealing in H2 at high temperature) showed on/off current (Ion/Ioff) ratios up to 103 at room temperature, suggesting the semiconducting nature of the narrow GNRs. Novel GNR-GNR and GNR-CNT crossbars were fabricated by transferring GNR arrays across GNR and CNT arrays, respectively. The production of such ordered graphene nanoribbon architectures may allow for large scale integration of GNRs into nanoelectronics or optoelectronics.
基金financially supported by the National Key R&D Program of China (2016YFA0202302)the State Key Program of National Natural Science Foundation of China (51633007)the National Natural Science Foundation of China (51773147, 51803149 and 51973151)
文摘Lithium-fluorinated carbon(Li-CFx)batteries have become one of the most widely applied power sources for high energy density applications because of the advantages provided by the CFx cathode.Moreover,the large gap between the practical and theoretical potentials alongside the stoichiometric limit of commercial graphite fluorides indicates the potential for further energy improvement.Herein,monolayer fluorinated graphene nanoribbons(F-GNRs)were fabricated by unzipping single-walled carbon nanotubes(SWCNTs)using pure F2 gas at high temperature,which delivered an unprecedented energy density of 2738.45 W h kg^(−1)due to the combined effect of a high fluorination degree and discharge plateau,realized by the abundant edges and destroyed periodic structure,respectively.Furthermore,at a high fluorination temperature,the theoretical calculation confirmed a zigzag pathway of fluorine atoms that were adsorbed outside of the SWCNTs and hence initiated the spontaneous process of unzipping SWCNTs to form the monolayer F-GNRs.The controllable fluorination of SWCNTs provided a feasible approach for preparing CFx compounds for different applications,especially for ultrahigh-energy-density cathodes.
基金supported by the National Natural Science Foundation of China (No. 51779236)the NSFC- Shandong Joint Fund Project (No. U1706226)the National Key Research and Development Program (No. 2016YFC 0303401)
文摘This study investigates strategies for solving the system reliability of large three-dimensional jacket structures.These structural systems normally fail as a result of a series of different components failures.The failure characteristics are investigated under various environmental conditions and direction combinations.Theβ-unzipping technique is adopted to determine critical failure components,and the entire system is simplified as a series-parallel system to approximately evaluate the structural system reliability.However,this approach needs excessive computational effort for searching failure components and failure paths.Based on a trained artificial neural network(ANN),which can be used to approximate the implicit limit-state function of a complicated structure,a new alternative procedure is proposed to improve the efficiency of the system reliability analysis method.The failure probability is calculated through Monte Carlo simulation(MCS)with Latin hypercube sampling(LHS).The features and applicability of the above procedure are discussed and compared using an example jacket platform located in Chengdao Oilfield,Bohai Sea,China.This study provides a reference for the evaluation of the system reliability of jacket structures.
文摘商业化的多壁碳纳米管通常是相互缠绕且紧密团聚,长度高达数十微米,不利于电解液离子的传输,尤其是难以利用碳纳米管内部空间。本文通过简单的化学氧化方法从横向和纵向同时裁剪多壁碳纳米管,形成弯曲的石墨烯带(CGS),将其浸入0.1 mol L^(-1)高锰酸钾溶液中,合成了CGS-MnO_(2)复合材料。利用FESEM、TEM、XRD、Raman对CGS-MnO_(2)的形貌和结构进行详细表征,结果表明无定形MnO_(2)成功地锚定在CGS的表面。在三电极体系中,CGS-MnO_(2)在2 mV s^(-1)的扫速下电容值达到236 F g^(-1),甚至在100 mV s^(-1)下电容仍能保持127 F g^(-1),远高于对比样品的电容值,例如MWCNTs(15 F g^(-1)),CGS(88 F g^(-1))和MWCNTs-MnO_(2)复合材料(111 F g^(-1))。此外,该材料还表现出优异的循环稳定性能,循环1000次后电容仍然保持97%。
文摘Hepatitis C virus(HCV)helicase is a molecular motor that splits nucleic acid duplex structures during viral replication,therefore representing a promising target for antiviral treatment.Hence,a detailed understanding of the mechanism by which it operates would facilitate the development of efficient drug-assisted therapies aiming to inhibit helicase activity.Despite extensive investigations performed in the past,a thorough understanding of the activity of this important protein was lacking since the underlying internal conformational motions could not be resolved.Here we review investigations that have been previously performed by us for HCV helicase.Using methods of structure-based computational modelling it became possible to follow entire operation cycles of this motor protein in structurally resolved simulations and uncover the mechanism by which it moves along the nucleic acid and accomplishes strand separation.We also discuss observations from that study in the light of recent experimental studies that confirm our findings.
