In the pursuit of carbon neutrality,hydrogen(H_(2))is often hailed as the ideal fuel for fuel cell vehicles(FCVs)due to its zero-emission nature and high gravimetric energy density.However,its low volumetric density n...In the pursuit of carbon neutrality,hydrogen(H_(2))is often hailed as the ideal fuel for fuel cell vehicles(FCVs)due to its zero-emission nature and high gravimetric energy density.However,its low volumetric density necessitates high-pressure on-board storage(up to 700 bar),which are costly and pose significant safety risks.To cope with these challenges,the U.S.Department of energy(DOE)has set ambitious targets for hydrogen storage systems,aiming for a gravimetric capacity of 6.5 wt%with a volumetric capacity of 50 g L^(-1).Porous crystals,exemplified by metal-organic frameworks(MOFs)[1,2],covalent organic frameworks(COFs),and hydrogen-bonded organic frameworks(HOFs)[3],have shown promise for hydrogen storage at 77 K with delivery at 160 K under significantly lower pressures(≤100 bar).展开更多
In this work grand canonical Monte Carlo simulations were performed to study gas separation in three pairs of isoreticular metal-organic frameworks (IRMOFs) with and without catenation at room temperature.Mixture comp...In this work grand canonical Monte Carlo simulations were performed to study gas separation in three pairs of isoreticular metal-organic frameworks (IRMOFs) with and without catenation at room temperature.Mixture composed of CO2 and H2 was selected as the model system to separate.The results show that CO2 selectivity in catenated MOFs with multi-porous frameworks is much higher than their non-catenated counterparts.The simulations also show that the electrostatic interactions are very important for the selectivity,and the contributions of different electrostatic interactions are different,depending on pore size,pressure and mixture composition.In fact,changing the electrostatic interactions can even qualitatively change the adsorption behavior.A general conclusion is that the electrostatic interactions between adsorbate molecules and the framework atoms play a dominant role at low pressures,and these interactions in catenated MOFs have much more pronounced effects than those in their non-catenated counterparts,while the electrostatic interactions between adsorbate molecules become evident with increasing pressure,and eventually dominant.展开更多
A systematic molecular simulation study was performed to investigate the effect of catenation on methane adsorption in metal-organic frameworks(MOFs).Four pairs of isoreticular MOFs(IRMOFs)with and without catenation ...A systematic molecular simulation study was performed to investigate the effect of catenation on methane adsorption in metal-organic frameworks(MOFs).Four pairs of isoreticular MOFs(IRMOFs)with and without catenation were adopted and their capacities for methane adsorption were compared at room temperature.The present work showed that catenation could greatly enhance the storage capacity of methane in MOFs,due to the formation of additional small pores and adsorption sites formed by the catenation of frameworks.In addition,the simulation results obtained at 298K and 3.5MPa showed that catenated MOFs could easily meet the requirement for methane storage in porous materials.展开更多
The safety of offshore pipeline has drawn a great deal of attention during deepwater installation due to the combined actions of high external pressure, axial tension, and bending moment. Meanwhile, the pipeline confi...The safety of offshore pipeline has drawn a great deal of attention during deepwater installation due to the combined actions of high external pressure, axial tension, and bending moment. Meanwhile, the pipeline configuration has a remarkable effect on the structural behaviour of the tube. The special studies focus on the deepwater S-lay technique in the present paper. The stiffened catenary theory is applied to establish the static equilibrium governing differential equation of a pipe element, and the solution equations of the total pipeline configuration from a lay-barge over a stinger to the seabed are derived, The numerical iteration method for solving pipeline configuration is described in detail, and the corresponding program is developed to conduct the analysis of effects of various parameters such as laying water depth, pipe diameter, thickness of concrete weighted coating layer, stinger length, control strain, and axial tension on pipeline configuration. The results show that the laying water depth, the submerged weight of the pipe, and the axial tension are the critical factors influencing pipeline configuration. In addition, geometrical parameters of the stinger such as length, radius, and shape have an important effect on the pipe-laying capacity of the vessel. The validity of the program is further verified by means of a comparison with results obtained from the commercial finite element software OFFPIPE.展开更多
The rational reticular design of metal-organic frameworks(MOFs)from building units of known geometries is essential for enriching the diversity of MOF structures.Unexpected and intriguing structures,however,can also a...The rational reticular design of metal-organic frameworks(MOFs)from building units of known geometries is essential for enriching the diversity of MOF structures.Unexpected and intriguing structures,however,can also arise from subtle changes in the rigidity/length of organic linkers and/or synthetic conditions.Herein,we report three uranium-based MOF structures—i.e.,NU-135X(X=0,1,2)—synthesized from trigonal planar uranyl nodes and triptycene-based hexacarboxylate ligands with variable arm lengths.A new chiral 3,6-connected nuc net was observed in NU-1350,while the extended versions of the ligand led to 3-fold catenated MOFs(NU-1351 and NU-1352)with rare 3,6-connected cml-c3 nets.The differences in the topology of NU-1350 and NU-1351/NU-1352 could be attributed to the slight distortions of the shorter linker in the former from the ideal trigonal prism geometry to an octahedral geometry when coordinated to the trigonal planar uranyl nodes.展开更多
This article aims at providing an analysis of the Cantonese Motion-Directional Construction within a broad framework of cognitive linguistics and how it is relevant to translation. The analysis is different from other...This article aims at providing an analysis of the Cantonese Motion-Directional Construction within a broad framework of cognitive linguistics and how it is relevant to translation. The analysis is different from others in that it applies the cognitive constructional approach to Cantonese. It discusses examples of the argument structure of the Cantonese Motion-Directional Construction and demonstrates the strategies of our approach. In particular, we propose the Catenative Analysis of the Motion-Directional Construction and argue that the Construction signals conceptual subordination, which illustrates the event structure of the Construction. Furthermore, we consider the relationship of translation between Cantonese and English in realizing this Construction.展开更多
基金financial support from the National Natural Science Foundation of China(Nos.22271189,92356301,and 21522105)the Science and Technology Commission of Shanghai Municipality(Nos.21XD1402300,22QC1401500,21JC1401700,and 21DZ2260400)the Double First-Class Initiative Fund of ShanghaiTech University(SYLDX0052022).
文摘In the pursuit of carbon neutrality,hydrogen(H_(2))is often hailed as the ideal fuel for fuel cell vehicles(FCVs)due to its zero-emission nature and high gravimetric energy density.However,its low volumetric density necessitates high-pressure on-board storage(up to 700 bar),which are costly and pose significant safety risks.To cope with these challenges,the U.S.Department of energy(DOE)has set ambitious targets for hydrogen storage systems,aiming for a gravimetric capacity of 6.5 wt%with a volumetric capacity of 50 g L^(-1).Porous crystals,exemplified by metal-organic frameworks(MOFs)[1,2],covalent organic frameworks(COFs),and hydrogen-bonded organic frameworks(HOFs)[3],have shown promise for hydrogen storage at 77 K with delivery at 160 K under significantly lower pressures(≤100 bar).
基金Supported by the National Natural Science Foundation of China （20725622, 20706002, and 20876006）, Beijing Nova Program （2008B15） and the Dutch STW/CW Separation Technology Program （700.56.655-DPC.6243）.
文摘In this work grand canonical Monte Carlo simulations were performed to study gas separation in three pairs of isoreticular metal-organic frameworks (IRMOFs) with and without catenation at room temperature.Mixture composed of CO2 and H2 was selected as the model system to separate.The results show that CO2 selectivity in catenated MOFs with multi-porous frameworks is much higher than their non-catenated counterparts.The simulations also show that the electrostatic interactions are very important for the selectivity,and the contributions of different electrostatic interactions are different,depending on pore size,pressure and mixture composition.In fact,changing the electrostatic interactions can even qualitatively change the adsorption behavior.A general conclusion is that the electrostatic interactions between adsorbate molecules and the framework atoms play a dominant role at low pressures,and these interactions in catenated MOFs have much more pronounced effects than those in their non-catenated counterparts,while the electrostatic interactions between adsorbate molecules become evident with increasing pressure,and eventually dominant.
基金Supported by the National Natural Science Foundation of China （20706002, 20725622, 20876006） and Beijing Nova Program （2008B15）.
文摘A systematic molecular simulation study was performed to investigate the effect of catenation on methane adsorption in metal-organic frameworks(MOFs).Four pairs of isoreticular MOFs(IRMOFs)with and without catenation were adopted and their capacities for methane adsorption were compared at room temperature.The present work showed that catenation could greatly enhance the storage capacity of methane in MOFs,due to the formation of additional small pores and adsorption sites formed by the catenation of frameworks.In addition,the simulation results obtained at 298K and 3.5MPa showed that catenated MOFs could easily meet the requirement for methane storage in porous materials.
基金supported by the National Natural Science Foundation of China (Grant No. 51009122)the Fundamental Research Funds for the Central Universities (Grant No. 2010QNA4030)the National High Technology Research and Development Program of China (863 Program, Grant No. 2006AA09A105)
文摘The safety of offshore pipeline has drawn a great deal of attention during deepwater installation due to the combined actions of high external pressure, axial tension, and bending moment. Meanwhile, the pipeline configuration has a remarkable effect on the structural behaviour of the tube. The special studies focus on the deepwater S-lay technique in the present paper. The stiffened catenary theory is applied to establish the static equilibrium governing differential equation of a pipe element, and the solution equations of the total pipeline configuration from a lay-barge over a stinger to the seabed are derived, The numerical iteration method for solving pipeline configuration is described in detail, and the corresponding program is developed to conduct the analysis of effects of various parameters such as laying water depth, pipe diameter, thickness of concrete weighted coating layer, stinger length, control strain, and axial tension on pipeline configuration. The results show that the laying water depth, the submerged weight of the pipe, and the axial tension are the critical factors influencing pipeline configuration. In addition, geometrical parameters of the stinger such as length, radius, and shape have an important effect on the pipe-laying capacity of the vessel. The validity of the program is further verified by means of a comparison with results obtained from the commercial finite element software OFFPIPE.
基金the U.S.D epartm ent of Energy,National Nuclear Security Administration,under Award Number DE-NA0003763.This work made use of the EPIC facility of Northwestern University's NUANCE Center,which has received support from the Soft and Hybrid Nanotechnology Experimental(SHyNE)Resource(NSF NNCI-1542205)the MRSEC program(NSF DMR-1720139)at the Materials Research Center+4 种基金the International Institute for Nanotechnology(IIN)the Keck Foundationand the State of Illinois,through the IIN.This work made use of the IMSERC at Northwestern University,which has received support from the NSF(CHE-1048773 and DMR0521267)Soft and Hybrid Nanotechnology Experimental(SHyNE)Resource(NSF NNCI-1542205)the State of Illinois and International Institute for Nanotechnology(IIN).P.L.and J.F.S.acknowledge the Joint Center of Excellence in Integrated Nano-Systems(JCIN)at King Abdulaziz City for Science and Technology(KACST)and Northwestern University(NU).
文摘The rational reticular design of metal-organic frameworks(MOFs)from building units of known geometries is essential for enriching the diversity of MOF structures.Unexpected and intriguing structures,however,can also arise from subtle changes in the rigidity/length of organic linkers and/or synthetic conditions.Herein,we report three uranium-based MOF structures—i.e.,NU-135X(X=0,1,2)—synthesized from trigonal planar uranyl nodes and triptycene-based hexacarboxylate ligands with variable arm lengths.A new chiral 3,6-connected nuc net was observed in NU-1350,while the extended versions of the ligand led to 3-fold catenated MOFs(NU-1351 and NU-1352)with rare 3,6-connected cml-c3 nets.The differences in the topology of NU-1350 and NU-1351/NU-1352 could be attributed to the slight distortions of the shorter linker in the former from the ideal trigonal prism geometry to an octahedral geometry when coordinated to the trigonal planar uranyl nodes.
文摘This article aims at providing an analysis of the Cantonese Motion-Directional Construction within a broad framework of cognitive linguistics and how it is relevant to translation. The analysis is different from others in that it applies the cognitive constructional approach to Cantonese. It discusses examples of the argument structure of the Cantonese Motion-Directional Construction and demonstrates the strategies of our approach. In particular, we propose the Catenative Analysis of the Motion-Directional Construction and argue that the Construction signals conceptual subordination, which illustrates the event structure of the Construction. Furthermore, we consider the relationship of translation between Cantonese and English in realizing this Construction.
