The paper focuses on the four soldiers away from the battle field depicted in the short story Guests oftke nation written by Frank O＇Conner. The character analysis is achieved by the reflection of the human nature wh...The paper focuses on the four soldiers away from the battle field depicted in the short story Guests oftke nation written by Frank O＇Conner. The character analysis is achieved by the reflection of the human nature when the soldiers were temporarily living peacefully and their painful conflicts between duty as soldiers and human nature as men. Through the tragic fate of both the two executed Englishmen and the executors--two Irish men, the cruelty of the war is strongly condemned. The war mercilessly defeated the human nature cultivated through the friendship and knowing with each other.展开更多
With constant economic development and continuous improvement of living standards in Northeast China,rural tourism,as a new type of tourism,is increasingly favored. From the perspective of symbolic interaction theory,...With constant economic development and continuous improvement of living standards in Northeast China,rural tourism,as a new type of tourism,is increasingly favored. From the perspective of symbolic interaction theory,taking the current situation of rural tourism in Northeast China as an example,this paper explained the semiotic significance between hosts and guests in rural tourism. It established the evaluation indicators for authentic symbolic perception of rural tourism. Also,combined with the theories of sociology and anthropology,it studied the interaction between hosts and tourists of rural tourism in Northeast China.展开更多
Guests of the Nation is a short story written by Frank O’Connor,a driven and prodigious writer,who was arguably one of Ireland’s most complete man of letters in the 20th century.Despite the fact that he lived a life...Guests of the Nation is a short story written by Frank O’Connor,a driven and prodigious writer,who was arguably one of Ireland’s most complete man of letters in the 20th century.Despite the fact that he lived a life of many facets,he was best known for his short stories.In a life span of 63 years,he produced 11 volumes of short stories,among which the title story of Frank O’Con⁃nor’s landmark collection Guests of the Nation was always widely reviewed,generally in positive terms.As a story set against the background of the Irish War of Independence,Guests of the Nation depicts an extraordinary situation where Irish soldiers and Eng⁃lish hostages become friends.To perform their duty,the Irish guards executed the two English hostages although camaraderie was created among them.This short story has attracted numerous critics to analyze it from different perspectives,each of whom has their own notion on the theme of the story.However,most of the scholars focus on analyzing the characters,few of them have noticed bi⁃nary oppositions in the story.There are several pair of binary oppositions in the story,for instance,enemy and friends,friendship and duty,comedy and tragedy,life and death,etc.Therefore,the present paper will examine it from the perspective of binary oppo⁃sition,in an attempt to tap deep into the conflict between humanity and the national interest,as well as the absurdity of war.展开更多
Mr. Ma Xingrui, vice President ASTRIUM, at the headquarter ofof China Aerospace Science CASC on April 8, 2004. Mr. Bouvierand Technology said that ASTRIUM and CASC haveCorporation (CASC), met with Mr. basis for cooper...Mr. Ma Xingrui, vice President ASTRIUM, at the headquarter ofof China Aerospace Science CASC on April 8, 2004. Mr. Bouvierand Technology said that ASTRIUM and CASC haveCorporation (CASC), met with Mr. basis for cooperation, and expectedAntoine Bouvier, CEO of EADS to undertake wider collaboration展开更多
President Zhou Jue of the China Society for Human Rights Studies (CSHRS) met with the visiting del-egation of Fianna Fail, the Republican Party of Ireland in Beijing on July 23. Headed by Ms. Mary Hanafin, Government ...President Zhou Jue of the China Society for Human Rights Studies (CSHRS) met with the visiting del-egation of Fianna Fail, the Republican Party of Ireland in Beijing on July 23. Headed by Ms. Mary Hanafin, Government Chief展开更多
Luo Haocai, Vice-Chairman of the National Committee of the Chinese People＇s Political Consultative Conference （CPPCC） and President of China Society for Human Rights Studies （CSHRS）, met with Professor Hans Pette...Luo Haocai, Vice-Chairman of the National Committee of the Chinese People＇s Political Consultative Conference （CPPCC） and President of China Society for Human Rights Studies （CSHRS）, met with Professor Hans Petter Graver, Board Chairman of the Norwegian Center for Human Rights （NCHR）, University of Oslo on the afternoon of September 3. CSHRS Vice President and Secretary-general Dong Yunhu was present at the meeting.展开更多
Three guests with two moiety probes for different Cucurbit[n = 6—8]urils have been synthesized. They are N-(2-methylenethiophen)-adamataneamine, N-(2-methylene pyrrole)- adamataneamine and N-(2-methylenefurfuran)-ada...Three guests with two moiety probes for different Cucurbit[n = 6—8]urils have been synthesized. They are N-(2-methylenethiophen)-adamataneamine, N-(2-methylene pyrrole)- adamataneamine and N-(2-methylenefurfuran)-adamataneamine. The probes are methyle-nepyridyl typically for Q[6] and adamataneamine typically for Q[7]. The host-guest complexes of Cucurbit[n = 6—8]urils with these guests have been investigated by using NMR techniques and ESMS method. Also, thermoanalysis has been used for exploring relationship of enthalpy and stability of the host-guest complexes.展开更多
Viologen,as a type of strong electron acceptor,is prone to undergo electron transfer(ET)and change color under external stimuli.However,due to the easy aggrega-tion of viologen molecules,they usually suffer from poorfl...Viologen,as a type of strong electron acceptor,is prone to undergo electron transfer(ET)and change color under external stimuli.However,due to the easy aggrega-tion of viologen molecules,they usually suffer from poorfluorescence emission in the condensed phase.Herein,a new viologen derivative of VioCl_(2)⋅2Cl(1^(2+)⋅2Cl)was designed and synthesized,in which thefluorescence was enhanced by intro-ducing Me-β-CD to weaken the interactions between viologen molecules.Then a viologen-based host-guest supramolecule of 1^(2+)@Me-β-CD was obtained by elec-trostatic interactions.Photo-/chemo-responded guest 1^(2+)supplies 1^(2+)@Me-β-CD,a green and dark purple caused by intramolecular and intermolecular ET.Further-more,1^(2+)@Me-β-CD displays an additional thermal responsive purple color.The triple chromic behaviors all exhibit excellent reversibility and cycling stability.As expected,1^(2+)@Me-β-CD exhibits strong photoluminescence(PL)in solid-liquid dual states,presenting an improved quantum yield(Φ)from 1^(2+)(Φ_(s)=0.37%,Φ_(1)= 16.74%)to=1^(2+)@Me-β-CD(Φ_(s)= 10.45%,Φ_(1)= 25.86%),and thefluores-=cence intensity can be dynamically modulated by light,heat,and acid/base vapors.The multi-responsive chromism and tunablefluorescence of 1^(2+)@Me-β-CD allow for potential applications in information security and smart windows.展开更多
As the warm winter sun shone on a weekday afternoon, a thin, middle-aged man sat at the Cosmo Bar, taking a break from the hustle and bustle of modern life. As the first General Manager of the newly opened Pullman Bei...As the warm winter sun shone on a weekday afternoon, a thin, middle-aged man sat at the Cosmo Bar, taking a break from the hustle and bustle of modern life. As the first General Manager of the newly opened Pullman Beijing West Wanda Hotel, Joseph W.C. Mak, a Hong Kong citizen with more than 30 years of experience in the hospitality industry, was proud to see this hotel become operational in less than展开更多
Vice-President Xie Yuan met with Dan Stephenson, executive director of Overseas Partnerships for Golden Spike 150th Anniversary—known as Spike 150—and the executive director of Economic Bridge International on Jan 1...Vice-President Xie Yuan met with Dan Stephenson, executive director of Overseas Partnerships for Golden Spike 150th Anniversary—known as Spike 150—and the executive director of Economic Bridge International on Jan 17.Stephenson told his host that Spike 150, which was initiated by Utah Governor Gary Herbert and Xie spoke highly of Utah’s government and legislature in commemorating the efforts and contribution of Chinese people.展开更多
China 2009 World Philatelic Exhibition (‘China 2009’) Executive Committee sent its delegation to Geneva, Switzerland aiming for better results in invitation and publicity work,26 to 31, July,2008,when the Universal ...China 2009 World Philatelic Exhibition (‘China 2009’) Executive Committee sent its delegation to Geneva, Switzerland aiming for better results in invitation and publicity work,26 to 31, July,2008,when the Universal Postal Union Congress was underway,the delegation made an vivid introduction to‘China 2009’and the Host City Luo Yang.展开更多
On May 14,CPAFFC President Li Xiaolin,Vice-President Lin Yi and Vice-President Song Jingwu attended the opening ceremony and high-level plenary meeting of the Belt and Road Forum for International Cooperation.At the s...On May 14,CPAFFC President Li Xiaolin,Vice-President Lin Yi and Vice-President Song Jingwu attended the opening ceremony and high-level plenary meeting of the Belt and Road Forum for International Cooperation.At the same time,they held meetings themed'People-to-People Connectivity'.Chinese President Xi Jinping attended the opening cer-展开更多
A novel porphyrin-salen compound and corresponding zinc（Ⅱ） porphyrin-salen compound （ZnPSC10） covalently linked by a flexible alkoxy chain （-O（CH）10O--） have been synthesized and characterized. Molecular reco...A novel porphyrin-salen compound and corresponding zinc（Ⅱ） porphyrin-salen compound （ZnPSC10） covalently linked by a flexible alkoxy chain （-O（CH）10O--） have been synthesized and characterized. Molecular recognition of three N-heterocyclic guests, pyridine, 1,4-diazobycyclo[2,2,2]octane （DABCO） and pyrazine, with the host ZnPSC10 was investigated. Binding constants were determined by means of UV-vis titration method. The binding mode of ZnPSC10 with DABCO has been discussed in detail by using ^1H NMR. It was found that the conformations of the recognition system changed from closed to open with the adding of DABCO.展开更多
Power-conversion-efficiencies(PCEs)of organic solar cells(OSCs)in laboratory,normally processed by spin-coating technology with toxic halogenated solvents,have reached over 19%.However,there is usually a marked PCE dr...Power-conversion-efficiencies(PCEs)of organic solar cells(OSCs)in laboratory,normally processed by spin-coating technology with toxic halogenated solvents,have reached over 19%.However,there is usually a marked PCE drop when the bladecoating and/or green-solvents toward large-scale printing are used instead,which hampers the practical development of OSCs.Here,a new series of N-alkyl-tailored small molecule acceptors named YR-SeNF with a same molecular main backbone are developed by combining selenium-fused central-core and naphthalene-fused endgroup.Thanks to the N-alkyl engineering,NIR-absorbing YR-SeNF series show different crystallinity,packing patterns,and miscibility with polymeric donor.The studies exhibit that the molecular packing,crystallinity,and vertical distribution of active layer morphologies are well optimized by introducing newly designed guest acceptor associated with tailored N-alkyl chains,providing the improved charge transfer dynamics and stability for the PM6:L8-BO:YRSeNF-based OSCs.As a result,a record-high PCE approaching 19%is achieved in the blade-coating OSCs fabricated from a greensolvent o-xylene with high-boiling point.Notably,ternary OSCs offer robust operating stability under maximum-power-point tracking and well-keep>80%of the initial PCEs for even over 400 h.Our alkyl-tailored guest acceptor strategy provides a unique approach to develop green-solvent and blade-coating processed high-efficiency and operating stable OSCs,which paves a way for industrial development.展开更多
It has been recognized that a small amount of propane mixed with methane can change greatly in not only the thermodynamics but also the structural properties of gas hydrate.However,its mechanism is still not well unde...It has been recognized that a small amount of propane mixed with methane can change greatly in not only the thermodynamics but also the structural properties of gas hydrate.However,its mechanism is still not well understood yet.In this research,structure-Ⅱ(sⅡ)hydrate is synthesized using a methanepropane gas mixture with an initial mole ratio of 99:1,and it is found that large(5~(12)6~4)cages are cooccupied by multiple gases based on the rigid structure analysis of neutron diffraction data.The first principles calculation and molecular dynamics simulation are conducted to uncover the molecular mechanism for sⅡmethane-propane hydrate formation,revealing that the presence of propane inhibits the formation of structure-Ⅰ(sⅠ)hydrate but promotes sⅡhydrate formation.The results help to understand the accumulation mechanism of natural gas hydrate and benefit to optimize the condition for gas storage and transportation in hydrate form.展开更多
Two new Zn（Ⅱ）-MOFs were synthesized based on an asymmetric Schiff-base ligand LH, which is obtained by the condensation of 5-formyl-8-hydroxyquinoline and 3-pyridinecar- boxylic acid hydrazide. In different mixed s...Two new Zn（Ⅱ）-MOFs were synthesized based on an asymmetric Schiff-base ligand LH, which is obtained by the condensation of 5-formyl-8-hydroxyquinoline and 3-pyridinecar- boxylic acid hydrazide. In different mixed solvents, we get two new isomorphism compounds, [Zn（L）2]＇CaHsO2-2MeOH （1） and [Zn（L）2]＇CH2CIz＇2MeOH （2）. Compounds 1 and 2 have been characterized by single-crystal X-ray diffraction, elemental analysis and IR. Compound 1 crystallizes in monoclinic, space group P2/c, with a - 13.856（4）, b = 14.156（4）, c = 9.620（3）А, β = 110.167（5）°, V = 1771.3（9） /k3, Dc = 1.500 g/cm3, C3sH3sNsOsZn, Mr = 800.13, F（000） = 832, p（MoKa） = 0.761 mm-1, Z = 2, the final R = 0.0596 and wR = 0.1221 for 2112 observed reflections （I 〉 2σ（0）. Compound 2 belongs to monoclinic, space group P21/c, with a = 13.575（3）, b = 14.130（3）, c = 9.485（2） A, β = 107.908（3）°, V= 1731.2（6） A3, Dc = 1.529 g/cm3, CasH32C12NsO6Zn, Mr = 796.96, F（000） = 820, g（MoKa） = 0.926 mm-1, Z = 2, the final R -- 0.0527 and wR = 0.1395 for 2501 observed reflections （I 〉 2σ-（/））. The Zn（II） centers in both 1 and 2 display a distorted octahedral coordination geometry. The octahedral Zn（lI） nodes and L linkages build up 2-D nets consisting of parallelogram-like grids in the ab plane. The neighboring nets stack through hydrogen bonds to generate 3-D rhombic channels. In 1, the 1,4-dioxane and MeOH guests alternatively arrange in the channels and effectively take up the free space; while in 2, the CH2CI/guests are arranged in the channels. In addition, the encapsulated MeOH molecules are bonded to the framework by hydrogen bonds.展开更多
文摘The paper focuses on the four soldiers away from the battle field depicted in the short story Guests oftke nation written by Frank O＇Conner. The character analysis is achieved by the reflection of the human nature when the soldiers were temporarily living peacefully and their painful conflicts between duty as soldiers and human nature as men. Through the tragic fate of both the two executed Englishmen and the executors--two Irish men, the cruelty of the war is strongly condemned. The war mercilessly defeated the human nature cultivated through the friendship and knowing with each other.
基金Supported by Student Innovation Project of University of Science and Technology Liaoning in 2017(201710146000016)
文摘With constant economic development and continuous improvement of living standards in Northeast China,rural tourism,as a new type of tourism,is increasingly favored. From the perspective of symbolic interaction theory,taking the current situation of rural tourism in Northeast China as an example,this paper explained the semiotic significance between hosts and guests in rural tourism. It established the evaluation indicators for authentic symbolic perception of rural tourism. Also,combined with the theories of sociology and anthropology,it studied the interaction between hosts and tourists of rural tourism in Northeast China.
文摘Guests of the Nation is a short story written by Frank O’Connor,a driven and prodigious writer,who was arguably one of Ireland’s most complete man of letters in the 20th century.Despite the fact that he lived a life of many facets,he was best known for his short stories.In a life span of 63 years,he produced 11 volumes of short stories,among which the title story of Frank O’Con⁃nor’s landmark collection Guests of the Nation was always widely reviewed,generally in positive terms.As a story set against the background of the Irish War of Independence,Guests of the Nation depicts an extraordinary situation where Irish soldiers and Eng⁃lish hostages become friends.To perform their duty,the Irish guards executed the two English hostages although camaraderie was created among them.This short story has attracted numerous critics to analyze it from different perspectives,each of whom has their own notion on the theme of the story.However,most of the scholars focus on analyzing the characters,few of them have noticed bi⁃nary oppositions in the story.There are several pair of binary oppositions in the story,for instance,enemy and friends,friendship and duty,comedy and tragedy,life and death,etc.Therefore,the present paper will examine it from the perspective of binary oppo⁃sition,in an attempt to tap deep into the conflict between humanity and the national interest,as well as the absurdity of war.
文摘Mr. Ma Xingrui, vice President ASTRIUM, at the headquarter ofof China Aerospace Science CASC on April 8, 2004. Mr. Bouvierand Technology said that ASTRIUM and CASC haveCorporation (CASC), met with Mr. basis for cooperation, and expectedAntoine Bouvier, CEO of EADS to undertake wider collaboration
文摘President Zhou Jue of the China Society for Human Rights Studies (CSHRS) met with the visiting del-egation of Fianna Fail, the Republican Party of Ireland in Beijing on July 23. Headed by Ms. Mary Hanafin, Government Chief
文摘Luo Haocai, Vice-Chairman of the National Committee of the Chinese People＇s Political Consultative Conference （CPPCC） and President of China Society for Human Rights Studies （CSHRS）, met with Professor Hans Petter Graver, Board Chairman of the Norwegian Center for Human Rights （NCHR）, University of Oslo on the afternoon of September 3. CSHRS Vice President and Secretary-general Dong Yunhu was present at the meeting.
文摘Three guests with two moiety probes for different Cucurbit[n = 6—8]urils have been synthesized. They are N-(2-methylenethiophen)-adamataneamine, N-(2-methylene pyrrole)- adamataneamine and N-(2-methylenefurfuran)-adamataneamine. The probes are methyle-nepyridyl typically for Q[6] and adamataneamine typically for Q[7]. The host-guest complexes of Cucurbit[n = 6—8]urils with these guests have been investigated by using NMR techniques and ESMS method. Also, thermoanalysis has been used for exploring relationship of enthalpy and stability of the host-guest complexes.
基金National Natural Science Foundation of China,Grant/Award Numbers:21571126,62271299Shanghai Key Laboratory of High Temperature Superconductors。
文摘Viologen,as a type of strong electron acceptor,is prone to undergo electron transfer(ET)and change color under external stimuli.However,due to the easy aggrega-tion of viologen molecules,they usually suffer from poorfluorescence emission in the condensed phase.Herein,a new viologen derivative of VioCl_(2)⋅2Cl(1^(2+)⋅2Cl)was designed and synthesized,in which thefluorescence was enhanced by intro-ducing Me-β-CD to weaken the interactions between viologen molecules.Then a viologen-based host-guest supramolecule of 1^(2+)@Me-β-CD was obtained by elec-trostatic interactions.Photo-/chemo-responded guest 1^(2+)supplies 1^(2+)@Me-β-CD,a green and dark purple caused by intramolecular and intermolecular ET.Further-more,1^(2+)@Me-β-CD displays an additional thermal responsive purple color.The triple chromic behaviors all exhibit excellent reversibility and cycling stability.As expected,1^(2+)@Me-β-CD exhibits strong photoluminescence(PL)in solid-liquid dual states,presenting an improved quantum yield(Φ)from 1^(2+)(Φ_(s)=0.37%,Φ_(1)= 16.74%)to=1^(2+)@Me-β-CD(Φ_(s)= 10.45%,Φ_(1)= 25.86%),and thefluores-=cence intensity can be dynamically modulated by light,heat,and acid/base vapors.The multi-responsive chromism and tunablefluorescence of 1^(2+)@Me-β-CD allow for potential applications in information security and smart windows.
文摘As the warm winter sun shone on a weekday afternoon, a thin, middle-aged man sat at the Cosmo Bar, taking a break from the hustle and bustle of modern life. As the first General Manager of the newly opened Pullman Beijing West Wanda Hotel, Joseph W.C. Mak, a Hong Kong citizen with more than 30 years of experience in the hospitality industry, was proud to see this hotel become operational in less than
文摘Vice-President Xie Yuan met with Dan Stephenson, executive director of Overseas Partnerships for Golden Spike 150th Anniversary—known as Spike 150—and the executive director of Economic Bridge International on Jan 17.Stephenson told his host that Spike 150, which was initiated by Utah Governor Gary Herbert and Xie spoke highly of Utah’s government and legislature in commemorating the efforts and contribution of Chinese people.
文摘China 2009 World Philatelic Exhibition (‘China 2009’) Executive Committee sent its delegation to Geneva, Switzerland aiming for better results in invitation and publicity work,26 to 31, July,2008,when the Universal Postal Union Congress was underway,the delegation made an vivid introduction to‘China 2009’and the Host City Luo Yang.
文摘On May 14,CPAFFC President Li Xiaolin,Vice-President Lin Yi and Vice-President Song Jingwu attended the opening ceremony and high-level plenary meeting of the Belt and Road Forum for International Cooperation.At the same time,they held meetings themed'People-to-People Connectivity'.Chinese President Xi Jinping attended the opening cer-
基金financially supported by the National Natural Science Foundation of China(Nos.20931003 and 21071068)the National Science Foundation for Fostering Talents in Basic Research of the National Natural Science Foundation of China(No. J1103307)
文摘Received 23 November 2012 Received in revised form 13 December 2012 Accepted 18 December 2012 Available online 20 January 2013
基金Project supported by the National Natural Science Foundation of China （Nos. 20271030, 20303009） and the Key Laboratory of 0pto-Electronics Information Science and Technology of Ministry of Education.
文摘A novel porphyrin-salen compound and corresponding zinc（Ⅱ） porphyrin-salen compound （ZnPSC10） covalently linked by a flexible alkoxy chain （-O（CH）10O--） have been synthesized and characterized. Molecular recognition of three N-heterocyclic guests, pyridine, 1,4-diazobycyclo[2,2,2]octane （DABCO） and pyrazine, with the host ZnPSC10 was investigated. Binding constants were determined by means of UV-vis titration method. The binding mode of ZnPSC10 with DABCO has been discussed in detail by using ^1H NMR. It was found that the conformations of the recognition system changed from closed to open with the adding of DABCO.
基金the support from the NSFC (22209131, 22005121, 21875182, and 52173023)National Key Research and Development Program of China (2022YFE0132400)+4 种基金Key Scientific and Technological Innovation Team Project of Shaanxi Province (2020TD-002)111 project 2.0 (BP0618008)Open Fund of Jiangsu Engineering Laboratory of Light-Electricity-Heat Energy-Converting Materials and Applications (Changzhou University, GDRGCS2022002)Open Fund of Key Laboratory of Fluorine and Silicon for Energy Materials and Chemistry of Ministry of Education (Jiangxi Normal University, KFSEMC-202201)acquired at beamlines 7.3.3 and 11.0.1.2 at the Advanced Light Source, which is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC0205CH11231
文摘Power-conversion-efficiencies(PCEs)of organic solar cells(OSCs)in laboratory,normally processed by spin-coating technology with toxic halogenated solvents,have reached over 19%.However,there is usually a marked PCE drop when the bladecoating and/or green-solvents toward large-scale printing are used instead,which hampers the practical development of OSCs.Here,a new series of N-alkyl-tailored small molecule acceptors named YR-SeNF with a same molecular main backbone are developed by combining selenium-fused central-core and naphthalene-fused endgroup.Thanks to the N-alkyl engineering,NIR-absorbing YR-SeNF series show different crystallinity,packing patterns,and miscibility with polymeric donor.The studies exhibit that the molecular packing,crystallinity,and vertical distribution of active layer morphologies are well optimized by introducing newly designed guest acceptor associated with tailored N-alkyl chains,providing the improved charge transfer dynamics and stability for the PM6:L8-BO:YRSeNF-based OSCs.As a result,a record-high PCE approaching 19%is achieved in the blade-coating OSCs fabricated from a greensolvent o-xylene with high-boiling point.Notably,ternary OSCs offer robust operating stability under maximum-power-point tracking and well-keep>80%of the initial PCEs for even over 400 h.Our alkyl-tailored guest acceptor strategy provides a unique approach to develop green-solvent and blade-coating processed high-efficiency and operating stable OSCs,which paves a way for industrial development.
基金financially supported by the National Natural Science Foundation of China(21722609 and 21878260)the Zhejiang Provincial Natural Science Foundation of China(LR170B060001).
基金supported by the National Key Research and Development Program of China(2016YFA0401503 and 2018YFA0305700)the National Natural Science Foundation of China(11575288,91934303,21935001 and 11775011)+4 种基金the Strategic Priority Research ProgramKey Research Program of Frontier Sciences of the Chinese Academy of Sciences(XDB33000000,XDB25000000 and QYZDBSSW-SLH013)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y202003)the China Geological Survey(DD20190234)the Scientific Instrument Developing Project(ZDKYYQ20170001)of the Chinese Academy of Sciences。
文摘It has been recognized that a small amount of propane mixed with methane can change greatly in not only the thermodynamics but also the structural properties of gas hydrate.However,its mechanism is still not well understood yet.In this research,structure-Ⅱ(sⅡ)hydrate is synthesized using a methanepropane gas mixture with an initial mole ratio of 99:1,and it is found that large(5~(12)6~4)cages are cooccupied by multiple gases based on the rigid structure analysis of neutron diffraction data.The first principles calculation and molecular dynamics simulation are conducted to uncover the molecular mechanism for sⅡmethane-propane hydrate formation,revealing that the presence of propane inhibits the formation of structure-Ⅰ(sⅠ)hydrate but promotes sⅡhydrate formation.The results help to understand the accumulation mechanism of natural gas hydrate and benefit to optimize the condition for gas storage and transportation in hydrate form.
文摘Two new Zn（Ⅱ）-MOFs were synthesized based on an asymmetric Schiff-base ligand LH, which is obtained by the condensation of 5-formyl-8-hydroxyquinoline and 3-pyridinecar- boxylic acid hydrazide. In different mixed solvents, we get two new isomorphism compounds, [Zn（L）2]＇CaHsO2-2MeOH （1） and [Zn（L）2]＇CH2CIz＇2MeOH （2）. Compounds 1 and 2 have been characterized by single-crystal X-ray diffraction, elemental analysis and IR. Compound 1 crystallizes in monoclinic, space group P2/c, with a - 13.856（4）, b = 14.156（4）, c = 9.620（3）А, β = 110.167（5）°, V = 1771.3（9） /k3, Dc = 1.500 g/cm3, C3sH3sNsOsZn, Mr = 800.13, F（000） = 832, p（MoKa） = 0.761 mm-1, Z = 2, the final R = 0.0596 and wR = 0.1221 for 2112 observed reflections （I 〉 2σ（0）. Compound 2 belongs to monoclinic, space group P21/c, with a = 13.575（3）, b = 14.130（3）, c = 9.485（2） A, β = 107.908（3）°, V= 1731.2（6） A3, Dc = 1.529 g/cm3, CasH32C12NsO6Zn, Mr = 796.96, F（000） = 820, g（MoKa） = 0.926 mm-1, Z = 2, the final R -- 0.0527 and wR = 0.1395 for 2501 observed reflections （I 〉 2σ-（/））. The Zn（II） centers in both 1 and 2 display a distorted octahedral coordination geometry. The octahedral Zn（lI） nodes and L linkages build up 2-D nets consisting of parallelogram-like grids in the ab plane. The neighboring nets stack through hydrogen bonds to generate 3-D rhombic channels. In 1, the 1,4-dioxane and MeOH guests alternatively arrange in the channels and effectively take up the free space; while in 2, the CH2CI/guests are arranged in the channels. In addition, the encapsulated MeOH molecules are bonded to the framework by hydrogen bonds.
