Heat transport in one kind of double-bond linear chains of fullerenes （C60＇s） is investigated by the classical nonequilibrium molecular dynamics method. It is found that the negative differential thermal resistance...Heat transport in one kind of double-bond linear chains of fullerenes （C60＇s） is investigated by the classical nonequilibrium molecular dynamics method. It is found that the negative differential thermal resistance （NDTR） is more likely to occur at larger temperature difference and shorter length. In addition, with the increase of the length, the thermal conductivity of the chains increases, and NDTR region shrinks and vanishes in the end. The temperature profiles reveal that a large temperature jump exists at a high-temperature boundary of the chains when NDTR occurs. These results may be helpful for designing thermal devices where low-dimensional C60 polymers can be used.展开更多
Linear carbon chains(LCCs)are a one-dimensional sp1-hybridized allo trope of ca rbon.LCCs are extre mely unstable:The longer the LCCs,the less stable the materials.Thus,it is a big challenge to synthesize long LCCs.Al...Linear carbon chains(LCCs)are a one-dimensional sp1-hybridized allo trope of ca rbon.LCCs are extre mely unstable:The longer the LCCs,the less stable the materials.Thus,it is a big challenge to synthesize long LCCs.Although the research on the short LCCs,e.g.,polyynes,can be traced back to the 18th,LCCs are still not well-known compared to other allotropes of carbon,e.g.,fullerenes,carbon nanotubes and graphene.Therefore,introducing recent progress on LCCs is of great significance to draw more attention in the community of nanocarbons as well as nanomaterials in general.Theoretically,various excellent properties have been predicted.Experimentally,LCCs with different length in many kinds of forms have been successfully synthesized.In this review,we summarized recent studies of polyynic LCCs from both theoretical and experimental aspects.Also,perspectives are highlighted to point out the further investigations of the materials.展开更多
Linear carbon chains as new one-dimensional(1D)nanomaterials attract attention for the predicted outstanding properties.However,the high reactivity of linear carbon chains hampers further experimental research.To date...Linear carbon chains as new one-dimensional(1D)nanomaterials attract attention for the predicted outstanding properties.However,the high reactivity of linear carbon chains hampers further experimental research.To date,different methods have been developed to synthesize new materials containing linear carbon chains.Among them,the arc-discharge method is a practical way to prepare both finite and infinite linear carbon chains.This review provides a brief discussion of the recent progress in the techniques to prepare carbon chain-based materials and then focuses on the arc-discharge method.The configuration of apparatus,optimal conditions,and the corresponding mechanism of arc-discharge method to prepare long linear carbon chain inside multi-walled carbon nanotubes are summarized in detail.The characterization techniques are introduced to evaluate the quality of products.Moreover,remaining challenges and perspectives are presented for further investigation of long linear carbon chains.展开更多
Carbon materials have long been a subject of study, offering diverse properties based on their hybridized structures. Except sp^(2)-hybridized graphene and carbon nanotubes, the focus on sp^(1)-hybridized carbon chain...Carbon materials have long been a subject of study, offering diverse properties based on their hybridized structures. Except sp^(2)-hybridized graphene and carbon nanotubes, the focus on sp^(1)-hybridized carbon chains has garnered significant interest due to its unique predicted properties, despite limitations in research and development stemming from its high reactivity. This comprehensive review summaries recent advancements in synthetic methodologies and characterization of the sp^(1)-hybridized carbon chains, encompassing linear carbon chains and cyclo[n]carbons. The review traces significant milestones in synthesis and offers a thorough overview of various properties on linear and cyclic carbon chains, from their initial discovery to recent development. The advancing synthetic methods have led to practical breakthroughs, transitioning theoretical concepts into tangible carbon-chain materials. However, challenges persist in achieving controlled and scalable preparation due to the high reactivity associated with sp^(1)-hybridization. Future research prospects focus on fundamental studies, such as exploring the transition length from polyyne to carbyne and experimentally determining the properties of single carbon chains.This review underscores both the progress made and the compelling avenues for future exploration in the dynamic field of sp^(1)-hybridized carbon chains.展开更多
The thermodynamic properties of linear protein solutions are discussed by a statistical me-chanics theory with a lattice model. The numerical results show that the Gibbs function of the solution decreases, and the pro...The thermodynamic properties of linear protein solutions are discussed by a statistical me-chanics theory with a lattice model. The numerical results show that the Gibbs function of the solution decreases, and the protein chemical potential is enhanced with increase of the protein concentration for dilute solutions. The influences of chain length and temperature on the Gibbs function of the solution as well as the protein chemical potential are analyzed.As an application of the theory, the chemical potentials of some mutants of type I antifreeze proteins are computed and discussed.展开更多
Two new A-D-A porphyrin derivatives,denoted as XLP-I and XLP-II,were prepared through extending theπ-conjugation of thienothiophene-porphyrin center with phenylethynyl bridges and electron-deficient ethylrhodanine te...Two new A-D-A porphyrin derivatives,denoted as XLP-I and XLP-II,were prepared through extending theπ-conjugation of thienothiophene-porphyrin center with phenylethynyl bridges and electron-deficient ethylrhodanine terminal units,and varying the structures of alkyl chain(linear vs branched)on peripheral thienothiophene substitutions of porphyrin rings.Both molecules show strong absorption in UV–visible–near-infrared region,good thermal stability,suitable energy levels,and ordered molecular packing in solid state.In organic solar cells,PC71BM was used as electron acceptor,and porphyrin small molecules were used as electron donors.The device based on XLP-I exhibits a power conversion efficiency(PCE)of 8.30%,an open circuit voltage(Voc)of 0.894 eV,and a fill factor(FF)of 62.1%.In contrast,the device based on XLP-II presents an inferior performance with a PCE of 3.14%,a Voc of 0.847 eV,and a FF of 49.3%.The better performance of XLP-I based device is mainly attributed to its optimized film morphology,excellent absorption,and well-balanced charge transport properties.展开更多
Carbyne is an infinitely long linear chain of carbon atoms with sp1hybridization and the truly one-dimensional allotrope of carbon.While obtaining freestanding carbyne is still an open challenge,the study of confined ...Carbyne is an infinitely long linear chain of carbon atoms with sp1hybridization and the truly one-dimensional allotrope of carbon.While obtaining freestanding carbyne is still an open challenge,the study of confined carbyne,linear chains of carbon encapsulated in carbon nanotubes,provides a pathway to explore carbyne and its remarkable properties in a well-defined environment.In this review,we discuss the basics and recent advances in studying single confined carbyne chains by Raman spectroscopy,which is their primary spectroscopic characterization method.We highlight where single carbyne chain studies are needed to advance our understanding of confined carbyne as a material system and provide an overview of the open questions that need to be addressed and of those aspects currently under debate.展开更多
In this study,a novel linear polyimide chain(PTCDA-DCH)was used as an electrochemiluminescence(ECL)emitter,employing a chiral metal-organic framework(MOF)(Zn-Dcam-dabco)as the chiral selector and ferrocene(Fc)as a que...In this study,a novel linear polyimide chain(PTCDA-DCH)was used as an electrochemiluminescence(ECL)emitter,employing a chiral metal-organic framework(MOF)(Zn-Dcam-dabco)as the chiral selector and ferrocene(Fc)as a quencher to construct a chiral sensor for detecting histidine(His)enantiomers.Competitive interactions between Fc and His induce partial Fc desorption from the sensor surface,leading to ECL signal recovery.Differential Fc release due to the distinct binding affinities of Zn-Dcam-dabco for His enantiomers enabled precise chiral discrimination.Notably,the sensor achieved the quantitative detection of His enantiomers with an limits of detection(LOD)of 8μmol/L.Furthermore,the sensor demonstrated excellent recovery rates of 98.0%–104%for l-histidine(L-His)and 92.0%–95.9%for D-His in spiked milk samples,validating its reliability for real-sample analysis.This study provides a promising platform for ECL-based chiral recognition,bioanalysis,and the rapid assessment of amino acids in food products.展开更多
Two new complexes, [W2Ag2S8?Ca(DMF)6]n 1 and [WAgS4?Na(DMF)3]n 2, have been synthesized and characterized. Single-crystal X-ray analyses show both 1 and 2 have {WAgS4}n anion linear chains, but 1 has a discrete [Ca(DM...Two new complexes, [W2Ag2S8?Ca(DMF)6]n 1 and [WAgS4?Na(DMF)3]n 2, have been synthesized and characterized. Single-crystal X-ray analyses show both 1 and 2 have {WAgS4}n anion linear chains, but 1 has a discrete [Ca(DMF)6]2+ cation while 2 is a linear chain. UV-Visible-Near-IR spectroscopy data show that the bandgaps of the two complexes are 1.86 and 1.99 eV, respectively. Electrical conductivity measurements reveal the conductivities of 1 and 2 are 10?7 and 10?8 Scm?1, respectively and they exhibit thermally activated temperature depen- dence, which may be attributed to semiconductors.展开更多
Carbyne,as the truly one-dimensional carbon allotrope with sp-hybridization,has attracted significant interest in recent years,showing potential applications in next-generation molecular devices due to its ultimate on...Carbyne,as the truly one-dimensional carbon allotrope with sp-hybridization,has attracted significant interest in recent years,showing potential applications in next-generation molecular devices due to its ultimate one-atom thinness.Various excellent properties of carbyne have been predicted,however,free-standing carbyne sample is extremely unstable and the corresponding experimental researches and modifications are under-developed compared to other known carbon allotropes.The synthesis of carbyne has been slowly developed for the past decades.Recently,there have been several breakthroughs in in-situ synthesis and measurement of carbyne related materials,as well as the preparation of ultra-long carbon chains toward infinite carbyne.These progresses have aroused widespread discussion in the academic community.In this review,the latest approaches in the synthesis of sp carbon are summarized.We then discuss its extraordinary properties,including mechanical,electronic,magnetic,and optical properties,especially focusing on the regulations of these properties.Finally,we provide a perspective on the development of carbyne.展开更多
The syntheses and structures of a novel series of polynuclear coinage metal cluster compounds are discussed. The most fascinating structural characteristic of the Au-Ag alloy clusters with Au_18Ag_19 and Au_18Ag_19 co...The syntheses and structures of a novel series of polynuclear coinage metal cluster compounds are discussed. The most fascinating structural characteristic of the Au-Ag alloy clusters with Au_18Ag_19 and Au_18Ag_19 cores and phosphine ligands, which were prepared by the reduction of mononuclear coinage metal complexes R3PAuX and R3PAgX with NaBH4 in organic solution, is their construction from 13-atom gold-centred icosahedral Au_7Ag_6 building blocks. The structures of the polynuclear coinage metal clusters with R2dtc ligands are variable with either unlimited linear chain or triangular M3 units.展开更多
The carbon chain cations, HC2nO+(n=3-6) are produced via a pulsed laser vaporization supersonic expansion ion source in the gas phase. Their infrared spectra are measured via mass-selected infrared photodissociation s...The carbon chain cations, HC2nO+(n=3-6) are produced via a pulsed laser vaporization supersonic expansion ion source in the gas phase. Their infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of the CO “tagged”[HC2nO·CO]+ cation complexes in 1600-3500 cm-1 frequency range. The geometric and electronic structures of the [HC2nO·CO]+ complexes and the core HC2nO+(n=3-6) cations are determined with the aid of density functional theory calculations. These HC2nO+(n=3-6) ions are identified to be linear carbon chain derivatives terminally capped by hydrogen and oxygen. The triplet ground states are 10-15 kcal/mol lower in energy than the singlet states, indicating cumulene-like carbon chain structures.展开更多
The syntheses and structures of eleven novel polymeric transition metal complexes having one dimensional chain structures or three dimensional networks are summarized. They are prepared from the controlled assemblin...The syntheses and structures of eleven novel polymeric transition metal complexes having one dimensional chain structures or three dimensional networks are summarized. They are prepared from the controlled assembling reactions in organic solvents and characterized by X ray diffraction analyses. The spectroscopic or magnetic properties of some complexes are studied.展开更多
The mean-square exponential stability problem is investigated for a class of stochastic time-varying delay systems with Markovian jumping parameters. By decomposing the delay interval into multiple equidistant subinte...The mean-square exponential stability problem is investigated for a class of stochastic time-varying delay systems with Markovian jumping parameters. By decomposing the delay interval into multiple equidistant subintervals, a new delay-dependent and decay-rate-dependent criterion is presented based on constructing a novel Lyapunov functional and employing stochastic analysis technique. Besides, the decay rate has no conventional constraint and can be selected according to different practical conditions. Finally, two numerical examples are provided to show that the obtained result has less conservatism than some existing ones in the literature.展开更多
A new Dy-based coordination polymer, namely {[Dy（cptpy）_2（H_2O）_2]（TPT）（Cl）}_n（1, Hcptpy = 4-（4-carboxyphenyl）-4,2？：6？,4？？-terpyridine, TPT = 2,4,6-tri（4-pyridyl）-1,3,5-triazine, DMA = N,N-dimethylac...A new Dy-based coordination polymer, namely {[Dy（cptpy）_2（H_2O）_2]（TPT）（Cl）}_n（1, Hcptpy = 4-（4-carboxyphenyl）-4,2？：6？,4？？-terpyridine, TPT = 2,4,6-tri（4-pyridyl）-1,3,5-triazine, DMA = N,N-dimethylacetamide） has been solvothermally synthesized by the reactions of DyCl_3, Hcptpy and TPT in a mixture solvent of DMA and H_2O. Single-crystal X-ray structural analysis reveals that 1 is a 1D linear chain coordination polymer with quadrangle channels which are occupied by the TPT ligands. The compound has been characterized by singe-crystal analyses, thermogravimetry analyses and powder X-ray diffraction measurements. The antitumor activity of compound 1 and its corresponding organic ligands Hcptpy and TPT were then investigated against four human lung cancer cell lines（NCI-H460, Calu-3, A549 and NCI-H292） by MTT assay. It was found that compared with Hcptpy and TPT, compound 1 exerted rather potent activity against all of these cell lines.展开更多
The linear-chain structure in which three alpha particles are arranged in a straight line was initially proposed by H.Morinaga[1]as the structure of the Hoyle state of carbon-12[2].This unique idea attracted much atte...The linear-chain structure in which three alpha particles are arranged in a straight line was initially proposed by H.Morinaga[1]as the structure of the Hoyle state of carbon-12[2].This unique idea attracted much attention,but it was rejected because it could not explain the lifetime of the Hoyle state.Half a century later,the concept of the linear chain structure was revived in the physics of unstable nuclei,and experimental and theoretical research have demonstrated that this structure exists in carbon-14 and 16.The authors have conducted internationally recognized experimental research on the linear-chain structure of carbon-14 and carbon-16.展开更多
A new inelastic excitation and cluster-decay experiment was conducted to investigate the negative-parity linear-chain structure in 16C.The helium and beryllium isotopes emitted from the highly excited states of 16C an...A new inelastic excitation and cluster-decay experiment was conducted to investigate the negative-parity linear-chain structure in 16C.The helium and beryllium isotopes emitted from the highly excited states of 16C and the recoil target deuteron were detected in coincidence.The 16C excitation-energy spectra associated with different decay paths were reconstructed using the invariant mass method.Owing to the newly reconfigured detector setup,the detection acceptance was extended to a higher excitation-energy range,allowing a number of new resonant states to be observed beyond the previously reportedπ^(2)σ^(2)-bond positive-parity linear-chain band.Based on comparison with the AMD calculations for both resonance energies and relative decay widths,these newly observed states can be tentatively assigned as the 1^(-),3^(-),5^(-)and 1^(-)members of the negative-parity linear-chain molecular rotational band.More experimental studies are expected to directly measure the spins of these states.展开更多
In this paper,we present a new method for finding a fixed local-optimal policy for computing the customer lifetime value.The method is developed for a class of ergodic controllable finite Markov chains.We propose an a...In this paper,we present a new method for finding a fixed local-optimal policy for computing the customer lifetime value.The method is developed for a class of ergodic controllable finite Markov chains.We propose an approach based on a non-converging state-value function that fluctuates（increases and decreases） between states of the dynamic process.We prove that it is possible to represent that function in a recursive format using a one-step-ahead fixed-optimal policy.Then,we provide an analytical formula for the numerical realization of the fixed local-optimal strategy.We also present a second approach based on linear programming,to solve the same problem,that implement the c-variable method for making the problem computationally tractable.At the end,we show that these two approaches are related：after a finite number of iterations our proposed approach converges to same result as the linear programming method.We also present a non-traditional approach for ergodicity verification.The validity of the proposed methods is successfully demonstrated theoretically and,by simulated credit-card marketing experiments computing the customer lifetime value for both an optimization and a game theory approach.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11004082 and 11005048the Natural Science Foundation of Guangdong Province under Grant No 2014A030313367
文摘Heat transport in one kind of double-bond linear chains of fullerenes （C60＇s） is investigated by the classical nonequilibrium molecular dynamics method. It is found that the negative differential thermal resistance （NDTR） is more likely to occur at larger temperature difference and shorter length. In addition, with the increase of the length, the thermal conductivity of the chains increases, and NDTR region shrinks and vanishes in the end. The temperature profiles reveal that a large temperature jump exists at a high-temperature boundary of the chains when NDTR occurs. These results may be helpful for designing thermal devices where low-dimensional C60 polymers can be used.
基金the National Natural Science Foundation of China(No.51902353)the Natural ScienceFoundation of Guangdong Province(No.2019A1515011227)the Sun Yat-sen University(Nos.29000-18841218,2900031610028)。
文摘Linear carbon chains(LCCs)are a one-dimensional sp1-hybridized allo trope of ca rbon.LCCs are extre mely unstable:The longer the LCCs,the less stable the materials.Thus,it is a big challenge to synthesize long LCCs.Although the research on the short LCCs,e.g.,polyynes,can be traced back to the 18th,LCCs are still not well-known compared to other allotropes of carbon,e.g.,fullerenes,carbon nanotubes and graphene.Therefore,introducing recent progress on LCCs is of great significance to draw more attention in the community of nanocarbons as well as nanomaterials in general.Theoretically,various excellent properties have been predicted.Experimentally,LCCs with different length in many kinds of forms have been successfully synthesized.In this review,we summarized recent studies of polyynic LCCs from both theoretical and experimental aspects.Also,perspectives are highlighted to point out the further investigations of the materials.
基金Project supported by the Fund from the Huzhou Key Laboratory of Environmental Functional Materials and Pollution Control at Huzhou University
文摘Linear carbon chains as new one-dimensional(1D)nanomaterials attract attention for the predicted outstanding properties.However,the high reactivity of linear carbon chains hampers further experimental research.To date,different methods have been developed to synthesize new materials containing linear carbon chains.Among them,the arc-discharge method is a practical way to prepare both finite and infinite linear carbon chains.This review provides a brief discussion of the recent progress in the techniques to prepare carbon chain-based materials and then focuses on the arc-discharge method.The configuration of apparatus,optimal conditions,and the corresponding mechanism of arc-discharge method to prepare long linear carbon chain inside multi-walled carbon nanotubes are summarized in detail.The characterization techniques are introduced to evaluate the quality of products.Moreover,remaining challenges and perspectives are presented for further investigation of long linear carbon chains.
基金supported by National Natural Science Foundation of China (No. 52472059)Fundamental Research Funds for the Central Universities, Sun Yat-sen University (No. 22lgqb03)State Key Laboratory of Optoelectronic Materials and Technologies (No. OEMT-2022-ZRC-01)。
文摘Carbon materials have long been a subject of study, offering diverse properties based on their hybridized structures. Except sp^(2)-hybridized graphene and carbon nanotubes, the focus on sp^(1)-hybridized carbon chains has garnered significant interest due to its unique predicted properties, despite limitations in research and development stemming from its high reactivity. This comprehensive review summaries recent advancements in synthetic methodologies and characterization of the sp^(1)-hybridized carbon chains, encompassing linear carbon chains and cyclo[n]carbons. The review traces significant milestones in synthesis and offers a thorough overview of various properties on linear and cyclic carbon chains, from their initial discovery to recent development. The advancing synthetic methods have led to practical breakthroughs, transitioning theoretical concepts into tangible carbon-chain materials. However, challenges persist in achieving controlled and scalable preparation due to the high reactivity associated with sp^(1)-hybridization. Future research prospects focus on fundamental studies, such as exploring the transition length from polyyne to carbyne and experimentally determining the properties of single carbon chains.This review underscores both the progress made and the compelling avenues for future exploration in the dynamic field of sp^(1)-hybridized carbon chains.
基金This work was supported by the National Natural Science Foundation of China （No.10764003 and No.30560039）.
文摘The thermodynamic properties of linear protein solutions are discussed by a statistical me-chanics theory with a lattice model. The numerical results show that the Gibbs function of the solution decreases, and the protein chemical potential is enhanced with increase of the protein concentration for dilute solutions. The influences of chain length and temperature on the Gibbs function of the solution as well as the protein chemical potential are analyzed.As an application of the theory, the chemical potentials of some mutants of type I antifreeze proteins are computed and discussed.
基金the national key R&D program for international collaboration(No.2021YFE0191500)the National Natural Science Foundation of China(No.51473053)+3 种基金the Natural Science Foundation of Hunan Province(No.2019JJ50603)the Peacock Team Project funding from Shenzhen Science and Technology Innovation Committee(No.KQTD2015033110182370)the Fundamental Research Project funding from Shenzhen Science and Technology Innovation Committee(No.JCYJ 20190809150213448).X.Zhu thanks the financial support from Hong Kong Research Grants Council(HKBU 12304320).
文摘Two new A-D-A porphyrin derivatives,denoted as XLP-I and XLP-II,were prepared through extending theπ-conjugation of thienothiophene-porphyrin center with phenylethynyl bridges and electron-deficient ethylrhodanine terminal units,and varying the structures of alkyl chain(linear vs branched)on peripheral thienothiophene substitutions of porphyrin rings.Both molecules show strong absorption in UV–visible–near-infrared region,good thermal stability,suitable energy levels,and ordered molecular packing in solid state.In organic solar cells,PC71BM was used as electron acceptor,and porphyrin small molecules were used as electron donors.The device based on XLP-I exhibits a power conversion efficiency(PCE)of 8.30%,an open circuit voltage(Voc)of 0.894 eV,and a fill factor(FF)of 62.1%.In contrast,the device based on XLP-II presents an inferior performance with a PCE of 3.14%,a Voc of 0.847 eV,and a FF of 49.3%.The better performance of XLP-I based device is mainly attributed to its optimized film morphology,excellent absorption,and well-balanced charge transport properties.
基金funding from the Deutsche Forschungsgemeinschaft(DFG)under the Emmy Noether Initiative(HE 8642/1-1)
文摘Carbyne is an infinitely long linear chain of carbon atoms with sp1hybridization and the truly one-dimensional allotrope of carbon.While obtaining freestanding carbyne is still an open challenge,the study of confined carbyne,linear chains of carbon encapsulated in carbon nanotubes,provides a pathway to explore carbyne and its remarkable properties in a well-defined environment.In this review,we discuss the basics and recent advances in studying single confined carbyne chains by Raman spectroscopy,which is their primary spectroscopic characterization method.We highlight where single carbyne chain studies are needed to advance our understanding of confined carbyne as a material system and provide an overview of the open questions that need to be addressed and of those aspects currently under debate.
基金financially supported by the Natural Science Foundation of Shandong Province,China(Nos.ZR2020QB065 and ZR2021MB121)。
文摘In this study,a novel linear polyimide chain(PTCDA-DCH)was used as an electrochemiluminescence(ECL)emitter,employing a chiral metal-organic framework(MOF)(Zn-Dcam-dabco)as the chiral selector and ferrocene(Fc)as a quencher to construct a chiral sensor for detecting histidine(His)enantiomers.Competitive interactions between Fc and His induce partial Fc desorption from the sensor surface,leading to ECL signal recovery.Differential Fc release due to the distinct binding affinities of Zn-Dcam-dabco for His enantiomers enabled precise chiral discrimination.Notably,the sensor achieved the quantitative detection of His enantiomers with an limits of detection(LOD)of 8μmol/L.Furthermore,the sensor demonstrated excellent recovery rates of 98.0%–104%for l-histidine(L-His)and 92.0%–95.9%for D-His in spiked milk samples,validating its reliability for real-sample analysis.This study provides a promising platform for ECL-based chiral recognition,bioanalysis,and the rapid assessment of amino acids in food products.
基金This research was supported by the State Key Laboratory of Structural Chemistry, the National Science and Technology of China (001CB1089), the Chinese Academy of Sciences (CAS), the National Science Foundation of China (20273073, 20333070, 90206040)
文摘Two new complexes, [W2Ag2S8?Ca(DMF)6]n 1 and [WAgS4?Na(DMF)3]n 2, have been synthesized and characterized. Single-crystal X-ray analyses show both 1 and 2 have {WAgS4}n anion linear chains, but 1 has a discrete [Ca(DMF)6]2+ cation while 2 is a linear chain. UV-Visible-Near-IR spectroscopy data show that the bandgaps of the two complexes are 1.86 and 1.99 eV, respectively. Electrical conductivity measurements reveal the conductivities of 1 and 2 are 10?7 and 10?8 Scm?1, respectively and they exhibit thermally activated temperature depen- dence, which may be attributed to semiconductors.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12174348 and 62027816)the China Postdoctoral Science Foundation(Grant Nos.2018M630830 and 2019T120631)+1 种基金the Natural Science Foundation of Henan Province,China(Grant No.212300410410)the Fund from the Henan Center for Outstanding Overseas Scientists(Grant No.GZS201903)
文摘Carbyne,as the truly one-dimensional carbon allotrope with sp-hybridization,has attracted significant interest in recent years,showing potential applications in next-generation molecular devices due to its ultimate one-atom thinness.Various excellent properties of carbyne have been predicted,however,free-standing carbyne sample is extremely unstable and the corresponding experimental researches and modifications are under-developed compared to other known carbon allotropes.The synthesis of carbyne has been slowly developed for the past decades.Recently,there have been several breakthroughs in in-situ synthesis and measurement of carbyne related materials,as well as the preparation of ultra-long carbon chains toward infinite carbyne.These progresses have aroused widespread discussion in the academic community.In this review,the latest approaches in the synthesis of sp carbon are summarized.We then discuss its extraordinary properties,including mechanical,electronic,magnetic,and optical properties,especially focusing on the regulations of these properties.Finally,we provide a perspective on the development of carbyne.
文摘The syntheses and structures of a novel series of polynuclear coinage metal cluster compounds are discussed. The most fascinating structural characteristic of the Au-Ag alloy clusters with Au_18Ag_19 and Au_18Ag_19 cores and phosphine ligands, which were prepared by the reduction of mononuclear coinage metal complexes R3PAuX and R3PAgX with NaBH4 in organic solution, is their construction from 13-atom gold-centred icosahedral Au_7Ag_6 building blocks. The structures of the polynuclear coinage metal clusters with R2dtc ligands are variable with either unlimited linear chain or triangular M3 units.
基金supported by the National Natural Science Foundation of China (No.21688102, No.21433005, and No.21573047)
文摘The carbon chain cations, HC2nO+(n=3-6) are produced via a pulsed laser vaporization supersonic expansion ion source in the gas phase. Their infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of the CO “tagged”[HC2nO·CO]+ cation complexes in 1600-3500 cm-1 frequency range. The geometric and electronic structures of the [HC2nO·CO]+ complexes and the core HC2nO+(n=3-6) cations are determined with the aid of density functional theory calculations. These HC2nO+(n=3-6) ions are identified to be linear carbon chain derivatives terminally capped by hydrogen and oxygen. The triplet ground states are 10-15 kcal/mol lower in energy than the singlet states, indicating cumulene-like carbon chain structures.
文摘The syntheses and structures of eleven novel polymeric transition metal complexes having one dimensional chain structures or three dimensional networks are summarized. They are prepared from the controlled assembling reactions in organic solvents and characterized by X ray diffraction analyses. The spectroscopic or magnetic properties of some complexes are studied.
基金supported by the Program for New Century Excellent Talents in University, the Graduate Innovation Program of Jiangsu Province (CX06B-051Z)the Scientific Research Foundation of Graduate School of Southeast University (YBJJ0929)
文摘The mean-square exponential stability problem is investigated for a class of stochastic time-varying delay systems with Markovian jumping parameters. By decomposing the delay interval into multiple equidistant subintervals, a new delay-dependent and decay-rate-dependent criterion is presented based on constructing a novel Lyapunov functional and employing stochastic analysis technique. Besides, the decay rate has no conventional constraint and can be selected according to different practical conditions. Finally, two numerical examples are provided to show that the obtained result has less conservatism than some existing ones in the literature.
基金supported by the grants from the Health and Family Planning Commission of Guizhou Province(gzwjkj2015-1-023)the Guizhou Province Science&Cooperative Project of 2015(No.7126)the Guiyang Science and Technology Project of 20141001(No.61)
文摘A new Dy-based coordination polymer, namely {[Dy（cptpy）_2（H_2O）_2]（TPT）（Cl）}_n（1, Hcptpy = 4-（4-carboxyphenyl）-4,2？：6？,4？？-terpyridine, TPT = 2,4,6-tri（4-pyridyl）-1,3,5-triazine, DMA = N,N-dimethylacetamide） has been solvothermally synthesized by the reactions of DyCl_3, Hcptpy and TPT in a mixture solvent of DMA and H_2O. Single-crystal X-ray structural analysis reveals that 1 is a 1D linear chain coordination polymer with quadrangle channels which are occupied by the TPT ligands. The compound has been characterized by singe-crystal analyses, thermogravimetry analyses and powder X-ray diffraction measurements. The antitumor activity of compound 1 and its corresponding organic ligands Hcptpy and TPT were then investigated against four human lung cancer cell lines（NCI-H460, Calu-3, A549 and NCI-H292） by MTT assay. It was found that compared with Hcptpy and TPT, compound 1 exerted rather potent activity against all of these cell lines.
文摘The linear-chain structure in which three alpha particles are arranged in a straight line was initially proposed by H.Morinaga[1]as the structure of the Hoyle state of carbon-12[2].This unique idea attracted much attention,but it was rejected because it could not explain the lifetime of the Hoyle state.Half a century later,the concept of the linear chain structure was revived in the physics of unstable nuclei,and experimental and theoretical research have demonstrated that this structure exists in carbon-14 and 16.The authors have conducted internationally recognized experimental research on the linear-chain structure of carbon-14 and carbon-16.
基金Supported by the National Key R&D Program of China(2023YFA1606403,2023YFE0101600,2022YFA1605100)the National Natural Science Foundation of China(12350007,12275007,12027809)。
文摘A new inelastic excitation and cluster-decay experiment was conducted to investigate the negative-parity linear-chain structure in 16C.The helium and beryllium isotopes emitted from the highly excited states of 16C and the recoil target deuteron were detected in coincidence.The 16C excitation-energy spectra associated with different decay paths were reconstructed using the invariant mass method.Owing to the newly reconfigured detector setup,the detection acceptance was extended to a higher excitation-energy range,allowing a number of new resonant states to be observed beyond the previously reportedπ^(2)σ^(2)-bond positive-parity linear-chain band.Based on comparison with the AMD calculations for both resonance energies and relative decay widths,these newly observed states can be tentatively assigned as the 1^(-),3^(-),5^(-)and 1^(-)members of the negative-parity linear-chain molecular rotational band.More experimental studies are expected to directly measure the spins of these states.
文摘In this paper,we present a new method for finding a fixed local-optimal policy for computing the customer lifetime value.The method is developed for a class of ergodic controllable finite Markov chains.We propose an approach based on a non-converging state-value function that fluctuates（increases and decreases） between states of the dynamic process.We prove that it is possible to represent that function in a recursive format using a one-step-ahead fixed-optimal policy.Then,we provide an analytical formula for the numerical realization of the fixed local-optimal strategy.We also present a second approach based on linear programming,to solve the same problem,that implement the c-variable method for making the problem computationally tractable.At the end,we show that these two approaches are related：after a finite number of iterations our proposed approach converges to same result as the linear programming method.We also present a non-traditional approach for ergodicity verification.The validity of the proposed methods is successfully demonstrated theoretically and,by simulated credit-card marketing experiments computing the customer lifetime value for both an optimization and a game theory approach.
