The photocatalytic production of syngas using a noble-metal-free catalytic system is a promising approach for renewable energy and environmental sustainability.In this study,we demonstrate an efficient catalytic syste...The photocatalytic production of syngas using a noble-metal-free catalytic system is a promising approach for renewable energy and environmental sustainability.In this study,we demonstrate an efficient catalytic system formed by integrating Co single sites,which act as the active sites,in covalent triazine frameworks(CTFs),which act as the photoabsorber,for the photocatalytic production of syngas from CO2 in aqueous solution.The enhanced light absorption of the CTFs,which contain intramolecular heterojunctions,in conjunction with 0.8 mmol L^‒1 of the Co complex enables excellent syngas production with a yield of 3303μmol g‒1(CO:H2=1.4:1)in 10 h,which is about three times greater than that achieved using CTF without a heterojunction.In the photocatalytic reaction,the coordinated single Co centers accept the photogenerated electrons from the CTF,and serve as active sites for CO2 conversion through an adsorption-activation-reaction mechanism.Theoretical calculations further reveal that the intramolecular heterojunctions highly promote photogenerated charge separation,thus boosting photocatalytic syngas production.This work reveals the promising potential of CTFs for single-metal-site-based photocatalysis.展开更多
A novel 3 D bismuth-organic framework(called Bi-TBAPy) single crystal was synthesized by employing 1,3,6,8-tetrakis(p-benzoic acid)pyrene(H4TBAPy) as an organic linker. The study demonstrates that the Bi-TBAPy not onl...A novel 3 D bismuth-organic framework(called Bi-TBAPy) single crystal was synthesized by employing 1,3,6,8-tetrakis(p-benzoic acid)pyrene(H4TBAPy) as an organic linker. The study demonstrates that the Bi-TBAPy not only possesses good chemical stability and suitable band edge positions for promising photocatalytic H2 evolution, but it also exhibits a typical ligand-to-metal charge transfer for favorable charge separation. The photocatalytic H2 evolution rates on the as-obtained Bi-TBAPy with different cocatalysts modified were examined with triethanolamine as the sacrificial reagent. Based on this, the hydrogen evolution rate of 140 μmol h-1 g-1 was obtained on the optimized sample with a loading of 2 wt% Pt as a cocatalyst. To the best of our knowledge, this is the first bismuth-based metal-organic framework(MOF) that functions as an effective photocatalyst for photocatalytic water reduction. Our study not only adds a new member to the family of photocatalyst materials, but also reveals the importance of cocatalyst modification in improving photocatalytic activity of MOFs.展开更多
Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells.Fe-N compounds with excellent electrocatalytic oxygen...Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells.Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells,which focuses on the Fe-N4 single-atom catalysts and the iron nitride materials(such as Fe2N and Fe3N).A hybridized catalyst having a hierarchical porous structure with regular macropores could enable the desired mass transfer efficiency in the catalytic process.In this study,we have constructed a new type of hybrid catalyst having iron and iron-nitrogen alloy nanoparticles(Fe-N austenite,termed as Fe-NA)embedded in the three-dimensional ordered macroporous N-doped carbon(3DOM Fe/Fe-NA@NC)by direct pyrolysis of single-source dicyandiamide-based iron metal-organic frameworks.The as-synthesized composites preserve the hierarchical porous carbon framework with ordered macropores and high specific surface area,incorporating the uniformly dispersed iron/iron-nitrogen austenite nanoparticles.Thereby,the striking architectural configuration embedded with highly active catalytic species delivers a superior oxygen reduction activity with a half-wave potential of 0.88 V and a subsequent superior Zn-air battery performance with high open-circuit voltage and continuous stability as compared to those using a commercial 20%Pt/C catalyst.展开更多
The livelihoods and well-being of Aboriginal and non-Aboriginal communities in remote and rural northern Australia are dependent upon the ecosystem services provided by tropical ecosystems. The well-being of all Austr...The livelihoods and well-being of Aboriginal and non-Aboriginal communities in remote and rural northern Australia are dependent upon the ecosystem services provided by tropical ecosystems. The well-being of all Australian citizens is measured by the Australia Bureau of Statistics （ABS） using socio-economic indicators. In this study we investigated the importance of non-market benefits derived from ecosystem services for Aboriginal well-being. Through a case study with the Mullunburra-Yidinji people in the Wet Tropics, Queensland, we applied the Millennium Ecosystem Assessment （MA） framework to identify the links between ecosystem services and the MA＇s six constituents of human well-being. The study demonstrated that cultural and provisioning services were key determinants of community well-being, and these are not currently measured by the ABS. We adapt the MA framework to include the ABS indicators and explore the potential strengths and weaknesses of the approach for measuring the well-being of contemporary remote and rural Aboriginal communities.展开更多
Electrochemical carbon dioxide reduction(CO_(2)RR)has been generally regarded as green technologies that can convert renewable energy such as sunlight and wind into fuels and valuable chemicals.However,the large‐scal...Electrochemical carbon dioxide reduction(CO_(2)RR)has been generally regarded as green technologies that can convert renewable energy such as sunlight and wind into fuels and valuable chemicals.However,the large‐scale implementation of CO_(2)RR is severely hindered by the lack of high‐performance CO_(2)RR electrocatalysts.Heterogeneous molecular catalysts and metal‐organic framework with well‐defined structure and high tunability of the metal centers and ligands show great promise for CO_(2)RR in terms of both fundamental understanding and practical application.Here,structural and interfacial engineering of these well‐defined metal‐organic ensembles is summarized.This review starts from the fundamental electrochemistry of CO_(2)RR and its evaluation criteria,and then moves to the heterogeneous molecular catalysts and metal‐organic framework with emphasis on the engineering of metal centers and ligands,their interaction with supports,as well as in situ reconstruction of metal‐organic ensembles.Summary and outlook are present in the end,with the hope to inspire and provoke more genuine thinking on the design and fabrication of efficient CO_(2)RR electrocatalysts.展开更多
The relation between narratives and agency can be sometimes considered as mutually constitutive. There are cases in which telling a story expresses higher degrees of agency, and respectively, agency is shaped as a nar...The relation between narratives and agency can be sometimes considered as mutually constitutive. There are cases in which telling a story expresses higher degrees of agency, and respectively, agency is shaped as a narrative that expresses the agent＇s reasons. From henceforth, I will contend that a narrative theory, beyond the personal identity problem, can also enlighten how the agent attains giving reasons for the action by making sense of sequences of events. In order to explain how agency is constituted from understanding and control, we must assume a primitive competence for narratives. Agency supposes an ordering that cannot be reduced to temporality, but expresses a certain sense of accomplishment that can be narratively constituted. In this context, I will examine Welleman＇s theory of emotions as an ordering framework of the events in structures of means-ends. A possible objection to his explanation of the agential narratives is that emotions themselves need to be understood as narrative processes. I suggest then that an enactivist approach would be a way of explaining the narrative constitution of agency. One virtue of this approach is that it harmonizes the biological and cultural components of the agency from the most basic layers to the ordinary folk-psychological narratives.展开更多
Over the last few decades, a diverse and expanded practice has emerged from the increasingly collaborative work developed among architects, urbanists, artists, and media designers. This collaboration has more and more...Over the last few decades, a diverse and expanded practice has emerged from the increasingly collaborative work developed among architects, urbanists, artists, and media designers. This collaboration has more and more developed a particular landscape of projects which share the same operative principles and modes of operation. The city at large has been the context where these projects have been implemented and developed with the will of bringing these types of experimentation to the people and to the public and social scale. Cities are continuously produced through entropic processes that mediate between complexity and immediacy. Information technology operates as a linkage able to set up new rules for communication between man and matter. In this framework, by looking at spatial interventions in the urban space, the aim of the paper is to dissect the modes in which spatial practitioners operate in the digital city through ＂Urban Machines＂ and how information technology becomes a tool for place-making. The paper looks at integrated systems or machines that have spatial, social, and environmental implication in how we experience the city. Machines imply ＂something that has been constructed＂ and ＂function with a specific purpose＂ while being composed by parts that respond to a ＂functioning whole＂. These interventions start from sharing the same principle： How do we generate through technologically mediated experiences opportunities for new types of production of（social）space？; How such systems shape our urban experience and deploy forms of participation in civic life？.展开更多
In this work, a bimetallic zeolitic imidazolate framework （ZIF） CoZn-ZIF was synthesized via a facile sol-vothermal approach and applied in lithiumion batteries. The as-prepared CoZn-ZIF shows a high reversible capa...In this work, a bimetallic zeolitic imidazolate framework （ZIF） CoZn-ZIF was synthesized via a facile sol-vothermal approach and applied in lithiumion batteries. The as-prepared CoZn-ZIF shows a high reversible capacity of 605.8 mA b g-i at a current density of 100 mA g^-1, far beyond the performance of the corresponding monometallic Co-ZIF- 67 and Zn-ZIF-8. Ex-situ synchrotron soft X-ray absorption spectroscopy, X-ray diffraction, and electron paramagnetic resonance techniques were employed to explore the Li^storage mechanism. The superior performance of CoZn-ZIF over Co-ZIF-67 and Zn-ZIF-8 could be mainly attributed to lithiation and delithiation of nitrogen atoms, accompanied by the breakage and recoordination of metal nitrogen bond. Morever, a few metal nitrogen bonds without recoordination will lead to the amorphization of CoZn-ZIF and the formation of few nitrogen radicals.展开更多
Covalent organic frameworks （COFs） have been widely applied in gas capture and separation, but the fluorescent property of COFs with large n-conjugated system tends to be underexplored. Here we report the fluorescen...Covalent organic frameworks （COFs） have been widely applied in gas capture and separation, but the fluorescent property of COFs with large n-conjugated system tends to be underexplored. Here we report the fluorescent properties of several COFs including TaTa, DhaTab, TRITER- 1 and TzDa and the effect of metal ions of Na＋, Mg2＋, K＋, Ca2＋, Cu2＋, Zn2＋, Pb2＋, Ag＋, Cd2＋ and Fe3＋ on the fluorescence of these COFs. The results show that only Fe3＋ significantly quenched the fluorescence of the studied COFs. The possibility of the four COFs for selective sensing of Fe3＋ was demonstrated. The possible mechanism of the effect of Fe3＋ on the fluorescence of the COFs was based on the absorption competition quenching.展开更多
We obtain a general invariance principle of G-Brownian motion for the law of the iterated logarithm(LIL for short). For continuous bounded independent and identically distributed random variables in G-expectation spac...We obtain a general invariance principle of G-Brownian motion for the law of the iterated logarithm(LIL for short). For continuous bounded independent and identically distributed random variables in G-expectation space, we also give an invariance principle for LIL. In some sense, this result is an extension of the classical Strassen's invariance principle to the case where probability measure is no longer additive. Furthermore,we give some examples as applications.展开更多
Covalent organic frameworks (COFs) are well known as the next generation of shape-persistent zeolite analogues, which have brought new impetus to the development of porous organic materials as well as two-dimensional ...Covalent organic frameworks (COFs) are well known as the next generation of shape-persistent zeolite analogues, which have brought new impetus to the development of porous organic materials as well as two-dimensional polymers. Since the advent of COFs in 2005, many striking findings have definitely proven their great potentials expanding applications across energy,environment and healthcare fields. With thorough exploration over a decade, research interest has been drawn on the scientific challenges on chemistry, while making full play of COF values has remained far from satisfactory yet. Thus opening an avenue to modulating COF assemblies on the multi-scale is no longer just an option, but a necessity for matching the application requirements with enhanced performances. In this mini-review, we summarize the recent progress on design of nanoscale COFs with varying forms. Detailed description is concentrated on the synthetic strategies of COF assemblies such as spheres, fibers,tubes, coatings and films, thereby shedding light on the flexible manipulation over dimensions, compositions and morphologies.Meanwhile, the advanced applications of nanoscale COFs have been discussed here with comparison of their bulky counterparts.展开更多
Electrochemical CO2 reduction(ECR)represents a promising strategy for utilizing CO2,an industrial waste,as an abundant and cheap carbon source for organic synthesis as well as storing intermittent renewable electricit...Electrochemical CO2 reduction(ECR)represents a promising strategy for utilizing CO2,an industrial waste,as an abundant and cheap carbon source for organic synthesis as well as storing intermittent renewable electricity from renewable sources.Efficient electrocatalysts allowing CO2 to be reduced selectively and actively are crucial since the ECR is a complex and sluggish process producing a variety of products.Metal-organic frameworks(MOFs)and covalentorganic frameworks(COFs)have emerged as versatile materials applicable in many fields due to their unique properties including high surface areas and tunable pore channels.Besides,the emerging reticular chemistry makes tuning their features on the atomic/molecular levels possible,thereby lending credence to the prospect of their utilizations.Herein,an overview of recent progress in employing framework material-based catalysts,including MOFs,COFs and their derivatives,for ECR is provided.The pertinent challenges,future trends,and opportunities associated with those systems are also discussed.展开更多
Based on the reduced-form approach, this paper investigates the pricing problems of default-risk bonds and credit default swaps(CDSs) for a fractional stochastic interest rate model with jump under the framework of pr...Based on the reduced-form approach, this paper investigates the pricing problems of default-risk bonds and credit default swaps(CDSs) for a fractional stochastic interest rate model with jump under the framework of primary-secondary. Using properties of the quasi-martingale with respect to the fractional Brownian motion and the jump technique in Park(2008), the authors first derive the explicit pricing formula of defaultable bonds. Then, based on the newly obtained pricing formula of defaultable bonds, the CDS is priced by the arbitrage-free principle. This paper presents an extension of the primary-secondary framework in Jarrow and Yu(2001).展开更多
The design of selective and efficient covalent organic frameworks(COFs)based electrocatalysts with tunable morphology for efficient CO_(2) reduction reaction(CO_(2)RR)to CH_(4) is highly desirable.Here,two kinds of an...The design of selective and efficient covalent organic frameworks(COFs)based electrocatalysts with tunable morphology for efficient CO_(2) reduction reaction(CO_(2)RR)to CH_(4) is highly desirable.Here,two kinds of anthraquinone-based COFs(i.e.,AAn-COF and OH-AAn-COF)with tunable 1D superstructures(e.g.,nanofibers(NF)and hollow tubes(HT))have been produced via Schiff-base condensation reaction.Interestingly,a rarely reported nanosheet-based self-template mechanism and a nanosheet-crimping mechanism have been demonstrated for the production of COF-based nanofibers and hollow tubes,respectively.Besides,the obtained COF-based superstructures can be post-modified with transition metals for efficient CO_(2)RR.Specifically,AAn-COF-Cu(NF)and OH-AAn-COF-Cu(HT)exhibit superior faradaic-efficiency with CH_(4)(FECH_(4))of 77%(-128.1 mA cm^(-2),-0.9 V)and 61%(-99.5 mA cm^(-2),-1.0 V)in a flow-cell,respectively.Noteworthy,the achieved FECH_(4) of AAn-COF-Cu(NF)(77%)is the highest one among reported crystalline COFs.This work provides a general methodology in exploring morphology-controlled COFs for electrocatalytic CO_(2)RR.展开更多
Four intensive uplift periods, i.e., 60–35, 25–17 and 12–8 Ma (but 18–13 Ma in the Himalayas of the southern Tibet), and since about 5 Ma, can be determined on the Tibetan Plateau by synthetical analysis of low-te...Four intensive uplift periods, i.e., 60–35, 25–17 and 12–8 Ma (but 18–13 Ma in the Himalayas of the southern Tibet), and since about 5 Ma, can be determined on the Tibetan Plateau by synthetical analysis of low-temperature thermo-chronology data, sedimentary deposit records, and structural deformation records of different areas. The strong tectonic uplift periods in different areas on the Tibetan Plateau are penecontemporaneous, except for the Himalayan area of the southern Tibet, where a rapid uplift and exhumation period, controlled by the activity of the South Tibetan Detachment System faults, occurred during 18–13 Ma. These strong uplift and exhumation periods correspond well to intensive deformation activity periods, suggesting tectonically-controlled uplift and exhumation. The deposit records, such as the distribution of coarse clastic sediments, the distribution of tectonically-controlled basins, stratigraphic discontinuousness or unconformity, and fault-controlled geomorphologic evolution, also match well with the strong uplift and exhumation periods. Expanding processes of the plateau are also discussed.展开更多
Photodetectors operating in the shortwave infrared region are of great significance due to their extensive applications in both commercial and military fields.Narrowbandgap two-dimensional layered materials(2DLMs)are ...Photodetectors operating in the shortwave infrared region are of great significance due to their extensive applications in both commercial and military fields.Narrowbandgap two-dimensional layered materials(2DLMs)are considered as the promising candidates for constructing nextgeneration high-performance infrared photodetectors.Nevertheless,the performance of 2DLMs-based photodetectors can hardly satisfy the requirements of practical applications due to their weak optical absorption.In the present study,a strategy was proposed to design high-performance shortwave infrared photodetectors by integrating metalorganic frameworks(MOFs)nanoparticles with excellent optical absorption characteristics and 2DLM with high mobility.Further,this study demonstrated the practicability of this strategy in a MOF/2DLM(Ni-CAT-1/Bi_(2)Se_(3))hybrid heterojunction photodetector.Due to the transfer of photo-generated carriers from the MOF to Bi_(2)Se_(3),the MOF nanoparticles integrated on the Bi_(2)Se_(3) layer can increase the photocurrent by 2-3 orders of magnitude.The resulting photodetector presented a high responsivity of 4725 A W^(−1) and a superior detectivity of 3.5×10^(13) Jones at 1500 nm.The outstanding performance of the hybrid heterojunction arises from the synergistic function of the enhanced optical absorption and photogating effect.In addition,the proposed device construction strategy combining MOF photosensitive materials with 2DLMs shows a high potential for the future high-performance shortwave infrared photodetectors.展开更多
文摘The photocatalytic production of syngas using a noble-metal-free catalytic system is a promising approach for renewable energy and environmental sustainability.In this study,we demonstrate an efficient catalytic system formed by integrating Co single sites,which act as the active sites,in covalent triazine frameworks(CTFs),which act as the photoabsorber,for the photocatalytic production of syngas from CO2 in aqueous solution.The enhanced light absorption of the CTFs,which contain intramolecular heterojunctions,in conjunction with 0.8 mmol L^‒1 of the Co complex enables excellent syngas production with a yield of 3303μmol g‒1(CO:H2=1.4:1)in 10 h,which is about three times greater than that achieved using CTF without a heterojunction.In the photocatalytic reaction,the coordinated single Co centers accept the photogenerated electrons from the CTF,and serve as active sites for CO2 conversion through an adsorption-activation-reaction mechanism.Theoretical calculations further reveal that the intramolecular heterojunctions highly promote photogenerated charge separation,thus boosting photocatalytic syngas production.This work reveals the promising potential of CTFs for single-metal-site-based photocatalysis.
基金supported by the National Natural Science Foundation of China(21633009,21522306,21633010)DICP&QIBEBT(UN201805)the Dalian Science Foundation for Distinguished Young Scholars(2017RJ02)~~
文摘A novel 3 D bismuth-organic framework(called Bi-TBAPy) single crystal was synthesized by employing 1,3,6,8-tetrakis(p-benzoic acid)pyrene(H4TBAPy) as an organic linker. The study demonstrates that the Bi-TBAPy not only possesses good chemical stability and suitable band edge positions for promising photocatalytic H2 evolution, but it also exhibits a typical ligand-to-metal charge transfer for favorable charge separation. The photocatalytic H2 evolution rates on the as-obtained Bi-TBAPy with different cocatalysts modified were examined with triethanolamine as the sacrificial reagent. Based on this, the hydrogen evolution rate of 140 μmol h-1 g-1 was obtained on the optimized sample with a loading of 2 wt% Pt as a cocatalyst. To the best of our knowledge, this is the first bismuth-based metal-organic framework(MOF) that functions as an effective photocatalyst for photocatalytic water reduction. Our study not only adds a new member to the family of photocatalyst materials, but also reveals the importance of cocatalyst modification in improving photocatalytic activity of MOFs.
文摘Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells.Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells,which focuses on the Fe-N4 single-atom catalysts and the iron nitride materials(such as Fe2N and Fe3N).A hybridized catalyst having a hierarchical porous structure with regular macropores could enable the desired mass transfer efficiency in the catalytic process.In this study,we have constructed a new type of hybrid catalyst having iron and iron-nitrogen alloy nanoparticles(Fe-N austenite,termed as Fe-NA)embedded in the three-dimensional ordered macroporous N-doped carbon(3DOM Fe/Fe-NA@NC)by direct pyrolysis of single-source dicyandiamide-based iron metal-organic frameworks.The as-synthesized composites preserve the hierarchical porous carbon framework with ordered macropores and high specific surface area,incorporating the uniformly dispersed iron/iron-nitrogen austenite nanoparticles.Thereby,the striking architectural configuration embedded with highly active catalytic species delivers a superior oxygen reduction activity with a half-wave potential of 0.88 V and a subsequent superior Zn-air battery performance with high open-circuit voltage and continuous stability as compared to those using a commercial 20%Pt/C catalyst.
文摘The livelihoods and well-being of Aboriginal and non-Aboriginal communities in remote and rural northern Australia are dependent upon the ecosystem services provided by tropical ecosystems. The well-being of all Australian citizens is measured by the Australia Bureau of Statistics （ABS） using socio-economic indicators. In this study we investigated the importance of non-market benefits derived from ecosystem services for Aboriginal well-being. Through a case study with the Mullunburra-Yidinji people in the Wet Tropics, Queensland, we applied the Millennium Ecosystem Assessment （MA） framework to identify the links between ecosystem services and the MA＇s six constituents of human well-being. The study demonstrated that cultural and provisioning services were key determinants of community well-being, and these are not currently measured by the ABS. We adapt the MA framework to include the ABS indicators and explore the potential strengths and weaknesses of the approach for measuring the well-being of contemporary remote and rural Aboriginal communities.
文摘Electrochemical carbon dioxide reduction(CO_(2)RR)has been generally regarded as green technologies that can convert renewable energy such as sunlight and wind into fuels and valuable chemicals.However,the large‐scale implementation of CO_(2)RR is severely hindered by the lack of high‐performance CO_(2)RR electrocatalysts.Heterogeneous molecular catalysts and metal‐organic framework with well‐defined structure and high tunability of the metal centers and ligands show great promise for CO_(2)RR in terms of both fundamental understanding and practical application.Here,structural and interfacial engineering of these well‐defined metal‐organic ensembles is summarized.This review starts from the fundamental electrochemistry of CO_(2)RR and its evaluation criteria,and then moves to the heterogeneous molecular catalysts and metal‐organic framework with emphasis on the engineering of metal centers and ligands,their interaction with supports,as well as in situ reconstruction of metal‐organic ensembles.Summary and outlook are present in the end,with the hope to inspire and provoke more genuine thinking on the design and fabrication of efficient CO_(2)RR electrocatalysts.
文摘The relation between narratives and agency can be sometimes considered as mutually constitutive. There are cases in which telling a story expresses higher degrees of agency, and respectively, agency is shaped as a narrative that expresses the agent＇s reasons. From henceforth, I will contend that a narrative theory, beyond the personal identity problem, can also enlighten how the agent attains giving reasons for the action by making sense of sequences of events. In order to explain how agency is constituted from understanding and control, we must assume a primitive competence for narratives. Agency supposes an ordering that cannot be reduced to temporality, but expresses a certain sense of accomplishment that can be narratively constituted. In this context, I will examine Welleman＇s theory of emotions as an ordering framework of the events in structures of means-ends. A possible objection to his explanation of the agential narratives is that emotions themselves need to be understood as narrative processes. I suggest then that an enactivist approach would be a way of explaining the narrative constitution of agency. One virtue of this approach is that it harmonizes the biological and cultural components of the agency from the most basic layers to the ordinary folk-psychological narratives.
文摘Over the last few decades, a diverse and expanded practice has emerged from the increasingly collaborative work developed among architects, urbanists, artists, and media designers. This collaboration has more and more developed a particular landscape of projects which share the same operative principles and modes of operation. The city at large has been the context where these projects have been implemented and developed with the will of bringing these types of experimentation to the people and to the public and social scale. Cities are continuously produced through entropic processes that mediate between complexity and immediacy. Information technology operates as a linkage able to set up new rules for communication between man and matter. In this framework, by looking at spatial interventions in the urban space, the aim of the paper is to dissect the modes in which spatial practitioners operate in the digital city through ＂Urban Machines＂ and how information technology becomes a tool for place-making. The paper looks at integrated systems or machines that have spatial, social, and environmental implication in how we experience the city. Machines imply ＂something that has been constructed＂ and ＂function with a specific purpose＂ while being composed by parts that respond to a ＂functioning whole＂. These interventions start from sharing the same principle： How do we generate through technologically mediated experiences opportunities for new types of production of（social）space？; How such systems shape our urban experience and deploy forms of participation in civic life？.
基金supported by the National Natural Science Foundation of China for Excellent Young Scholars(21522303)the National Natural Science Foundation of China(21373086)+3 种基金the Basic Research Project of Shanghai Science and Technology Committee(14JC1491000)the Large Instruments Open Foundation of East China Normal Universitythe National Key Basic Research Program of China(2013CB921800)the National High Technology Research and Development Program of China(2014AA123401)
文摘In this work, a bimetallic zeolitic imidazolate framework （ZIF） CoZn-ZIF was synthesized via a facile sol-vothermal approach and applied in lithiumion batteries. The as-prepared CoZn-ZIF shows a high reversible capacity of 605.8 mA b g-i at a current density of 100 mA g^-1, far beyond the performance of the corresponding monometallic Co-ZIF- 67 and Zn-ZIF-8. Ex-situ synchrotron soft X-ray absorption spectroscopy, X-ray diffraction, and electron paramagnetic resonance techniques were employed to explore the Li^storage mechanism. The superior performance of CoZn-ZIF over Co-ZIF-67 and Zn-ZIF-8 could be mainly attributed to lithiation and delithiation of nitrogen atoms, accompanied by the breakage and recoordination of metal nitrogen bond. Morever, a few metal nitrogen bonds without recoordination will lead to the amorphization of CoZn-ZIF and the formation of few nitrogen radicals.
基金supported by the National Basic Research Program of China (2015CB932001)the National Natural Science Foundation of China (21775056, 21777074)+1 种基金the Fundamental Research Funds for Central Universities (JUSRP51714B)Open Funds of the State Key Laboratory of Electroanalytical Chemistry (SKLEAC201705)
文摘Covalent organic frameworks （COFs） have been widely applied in gas capture and separation, but the fluorescent property of COFs with large n-conjugated system tends to be underexplored. Here we report the fluorescent properties of several COFs including TaTa, DhaTab, TRITER- 1 and TzDa and the effect of metal ions of Na＋, Mg2＋, K＋, Ca2＋, Cu2＋, Zn2＋, Pb2＋, Ag＋, Cd2＋ and Fe3＋ on the fluorescence of these COFs. The results show that only Fe3＋ significantly quenched the fluorescence of the studied COFs. The possibility of the four COFs for selective sensing of Fe3＋ was demonstrated. The possible mechanism of the effect of Fe3＋ on the fluorescence of the COFs was based on the absorption competition quenching.
基金supported by China Postdoctoral Science Foundation(Grant No.2013M541899)the Natural Science Foundation of Shandong Province of China(Grant Nos.ZR2013AQ021 and ZR2014AM002)+1 种基金National Natural Science Foundation of China(Grant Nos.11471190,11401414 and 11231005)the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20140299)
文摘We obtain a general invariance principle of G-Brownian motion for the law of the iterated logarithm(LIL for short). For continuous bounded independent and identically distributed random variables in G-expectation space, we also give an invariance principle for LIL. In some sense, this result is an extension of the classical Strassen's invariance principle to the case where probability measure is no longer additive. Furthermore,we give some examples as applications.
基金supported by the National Natural Science Foundation of China (21474015, 21774023)Science and Technology Commission of Shanghai Municipality (14ZR1402300)
文摘Covalent organic frameworks (COFs) are well known as the next generation of shape-persistent zeolite analogues, which have brought new impetus to the development of porous organic materials as well as two-dimensional polymers. Since the advent of COFs in 2005, many striking findings have definitely proven their great potentials expanding applications across energy,environment and healthcare fields. With thorough exploration over a decade, research interest has been drawn on the scientific challenges on chemistry, while making full play of COF values has remained far from satisfactory yet. Thus opening an avenue to modulating COF assemblies on the multi-scale is no longer just an option, but a necessity for matching the application requirements with enhanced performances. In this mini-review, we summarize the recent progress on design of nanoscale COFs with varying forms. Detailed description is concentrated on the synthetic strategies of COF assemblies such as spheres, fibers,tubes, coatings and films, thereby shedding light on the flexible manipulation over dimensions, compositions and morphologies.Meanwhile, the advanced applications of nanoscale COFs have been discussed here with comparison of their bulky counterparts.
基金financially supported by the National Natural Science Foundation of China(21671096 and 11775105)Shenzhen Peacock Plan(KQTD2016022620054656)。
文摘Electrochemical CO2 reduction(ECR)represents a promising strategy for utilizing CO2,an industrial waste,as an abundant and cheap carbon source for organic synthesis as well as storing intermittent renewable electricity from renewable sources.Efficient electrocatalysts allowing CO2 to be reduced selectively and actively are crucial since the ECR is a complex and sluggish process producing a variety of products.Metal-organic frameworks(MOFs)and covalentorganic frameworks(COFs)have emerged as versatile materials applicable in many fields due to their unique properties including high surface areas and tunable pore channels.Besides,the emerging reticular chemistry makes tuning their features on the atomic/molecular levels possible,thereby lending credence to the prospect of their utilizations.Herein,an overview of recent progress in employing framework material-based catalysts,including MOFs,COFs and their derivatives,for ECR is provided.The pertinent challenges,future trends,and opportunities associated with those systems are also discussed.
基金supported by the National Natural Science Foundation of China under Grant Nos.11401556,61304065 and 11471304the Fundamental Research Funds for the Central Universities under Grant No.WK2040000012
文摘Based on the reduced-form approach, this paper investigates the pricing problems of default-risk bonds and credit default swaps(CDSs) for a fractional stochastic interest rate model with jump under the framework of primary-secondary. Using properties of the quasi-martingale with respect to the fractional Brownian motion and the jump technique in Park(2008), the authors first derive the explicit pricing formula of defaultable bonds. Then, based on the newly obtained pricing formula of defaultable bonds, the CDS is priced by the arbitrage-free principle. This paper presents an extension of the primary-secondary framework in Jarrow and Yu(2001).
基金supported by the National Natural Science Foundation of China(21871141,21871142,21901122,22071109 and 92061101)the Natural Science Research of Jiangsu Higher Education Institutions of China(19KJB150011)+3 种基金China Postdoctoral Science Foundation(2018M630572 and 2019M651873)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX201171)Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Foundation of Jiangsu Collaborative Innovation Center of Biomedical Functional Materials.
文摘The design of selective and efficient covalent organic frameworks(COFs)based electrocatalysts with tunable morphology for efficient CO_(2) reduction reaction(CO_(2)RR)to CH_(4) is highly desirable.Here,two kinds of anthraquinone-based COFs(i.e.,AAn-COF and OH-AAn-COF)with tunable 1D superstructures(e.g.,nanofibers(NF)and hollow tubes(HT))have been produced via Schiff-base condensation reaction.Interestingly,a rarely reported nanosheet-based self-template mechanism and a nanosheet-crimping mechanism have been demonstrated for the production of COF-based nanofibers and hollow tubes,respectively.Besides,the obtained COF-based superstructures can be post-modified with transition metals for efficient CO_(2)RR.Specifically,AAn-COF-Cu(NF)and OH-AAn-COF-Cu(HT)exhibit superior faradaic-efficiency with CH_(4)(FECH_(4))of 77%(-128.1 mA cm^(-2),-0.9 V)and 61%(-99.5 mA cm^(-2),-1.0 V)in a flow-cell,respectively.Noteworthy,the achieved FECH_(4) of AAn-COF-Cu(NF)(77%)is the highest one among reported crystalline COFs.This work provides a general methodology in exploring morphology-controlled COFs for electrocatalytic CO_(2)RR.
基金supported by China Geological Survey (Grant No. 1212010610103)National Natural Science Foundation of China (Grant Nos. 40902060, 40672137)
文摘Four intensive uplift periods, i.e., 60–35, 25–17 and 12–8 Ma (but 18–13 Ma in the Himalayas of the southern Tibet), and since about 5 Ma, can be determined on the Tibetan Plateau by synthetical analysis of low-temperature thermo-chronology data, sedimentary deposit records, and structural deformation records of different areas. The strong tectonic uplift periods in different areas on the Tibetan Plateau are penecontemporaneous, except for the Himalayan area of the southern Tibet, where a rapid uplift and exhumation period, controlled by the activity of the South Tibetan Detachment System faults, occurred during 18–13 Ma. These strong uplift and exhumation periods correspond well to intensive deformation activity periods, suggesting tectonically-controlled uplift and exhumation. The deposit records, such as the distribution of coarse clastic sediments, the distribution of tectonically-controlled basins, stratigraphic discontinuousness or unconformity, and fault-controlled geomorphologic evolution, also match well with the strong uplift and exhumation periods. Expanding processes of the plateau are also discussed.
基金supported by the National Natural Science Foundation of China(21825103 and 51727809)the Natural Science Foundation of Hubei Province(2019CFA002)+1 种基金the Fundamental Research Funds for the Central Universities(2019kfyXMBZ018)China Postdoctoral Science Foundation(2021M691108)。
文摘Photodetectors operating in the shortwave infrared region are of great significance due to their extensive applications in both commercial and military fields.Narrowbandgap two-dimensional layered materials(2DLMs)are considered as the promising candidates for constructing nextgeneration high-performance infrared photodetectors.Nevertheless,the performance of 2DLMs-based photodetectors can hardly satisfy the requirements of practical applications due to their weak optical absorption.In the present study,a strategy was proposed to design high-performance shortwave infrared photodetectors by integrating metalorganic frameworks(MOFs)nanoparticles with excellent optical absorption characteristics and 2DLM with high mobility.Further,this study demonstrated the practicability of this strategy in a MOF/2DLM(Ni-CAT-1/Bi_(2)Se_(3))hybrid heterojunction photodetector.Due to the transfer of photo-generated carriers from the MOF to Bi_(2)Se_(3),the MOF nanoparticles integrated on the Bi_(2)Se_(3) layer can increase the photocurrent by 2-3 orders of magnitude.The resulting photodetector presented a high responsivity of 4725 A W^(−1) and a superior detectivity of 3.5×10^(13) Jones at 1500 nm.The outstanding performance of the hybrid heterojunction arises from the synergistic function of the enhanced optical absorption and photogating effect.In addition,the proposed device construction strategy combining MOF photosensitive materials with 2DLMs shows a high potential for the future high-performance shortwave infrared photodetectors.
