Dyad and triad census summarize much of the network level structural information of a given directed network. They have been found very useful in analyzing structural properties of social networks. This study aims to ...Dyad and triad census summarize much of the network level structural information of a given directed network. They have been found very useful in analyzing structural properties of social networks. This study aims to explore crisis communication network by following dyad and triad census analysis approach to investigate the association of microlevel communication patterns with organizational crisis. This study further tests hypothesis related to the process of data generation and tendency of the structural pattern of transitivity using dyad and triad census output. The changing communication network at Enron Corporation during the period of its crisis is analyzed in this study. Significant differences in the presence of different isomorphism classes or microlevel patterns of both dyad and triad census are noticed in crisis and non-crisis period network of Enron email corpus. It is also noticed that crisis communication network shows more transitivity compared to the non-crisis communication network.展开更多
A new copper phthalocyanine-fullerene dyad (CuPc-C-60) was synthesized by Diels-Alder adduct of corresponding CuPc and C-60. The chemical structure of this compound was characterized by elemental analysis, MS, IR, UV-...A new copper phthalocyanine-fullerene dyad (CuPc-C-60) was synthesized by Diels-Alder adduct of corresponding CuPc and C-60. The chemical structure of this compound was characterized by elemental analysis, MS, IR, UV-VIS and NMR.展开更多
In order to harness wind energy with high coefficients, horizontal axis wind turbines (HAWT), like propeller-type wind turbines, have an advantage in terms of practical utilization because of their scale merit. Howeve...In order to harness wind energy with high coefficients, horizontal axis wind turbines (HAWT), like propeller-type wind turbines, have an advantage in terms of practical utilization because of their scale merit. However, large size and high tip-speed ratio are inherently related to material strength problems and low frequency noise emissions to the environment. In contrast to HAWT, we will discuss a flapping-type turbine driven at low speed. The flapping turbine works using lift force like the HAWT, but employs a new wind turbine concept in the present report. The concept involves the unique flapping motion of a wind blade mounted on a Chebyshev-dyad linkage by which the wing transforms wind energy into mechanical rotation. Both static and dynamic numerical estimates are developed to optimize all fundamental parameters of this linkage in order to obtain the desired torque. In this paper, the results of primitive optimization for determining the fundamental characteristics of motion and the trajectory of the wind turbine blade are demonstrated in order to obtain smooth rotation of the generator-driving shaft. It is also shown that the present turbine can be driven at low speed with a suitable energy conversion rate. Moreover, the practicality of operating slow flapping-type wind turbines is demonstrated, focusing on usage near residential areas or, e.g., on rooftops owing to lower noise. The feasibility of “figure eight” trajectory diversity is discussed along with geometrical parameters. Assuming one-blade motion with a variable trajectory for optimization, the smooth motion and required torque at slow rotation speeds are studied.展开更多
The molecular orientations of conjugated materials on the substrate mainly include edge-on,face-on,and end-on.Edge-on and face-on orientations have been widely observed,while end-on orientation has been rarely reporte...The molecular orientations of conjugated materials on the substrate mainly include edge-on,face-on,and end-on.Edge-on and face-on orientations have been widely observed,while end-on orientation has been rarely reported.Since in organic solar cells(OSCs)charge transport is along the vertical direction,end-on orientation with conjugated backbones perpendicular to the substrate is recognized as the ideal microstructure for OSCs.In this work,we for the first time obtained the preferential end-on orientation in a conjugated molecular dyad that contains a conjugated backbone as donor and perylene bisimide side units as acceptor.This was realized by introducing a fused-ring structure to replace linear terthiophenes with conjugated backbones,yielding F-MDPBI and L-MDPBI respectively.Surprisingly,a shifting trend of the molecular orientation from dominating edge-on in L-MDPBI to preferential end-on in F-MDPBI was observed.As a consequence,vertical charge carrier mobilities in F-MDPBI are one order of magnitude higher than those with preferential edge-on orientation,so single-component OSCs based on this molecular dyad as a single photoactive layer provided a power conversion efficiency of 4.89% compared to 1.70% based on L-MDPBI with preferential edge-on orientation.展开更多
The performance of organic solar cells(OSCs)is mainly related to the bulk heterojunction(BHJ)microstructure of specific active layer systems,which is often in a metastable state.A promising strategy to address the abo...The performance of organic solar cells(OSCs)is mainly related to the bulk heterojunction(BHJ)microstructure of specific active layer systems,which is often in a metastable state.A promising strategy to address the abovementioned shortcomings of BHJs is to develop single-component active layer materials.Owing to the single-component small molecule materials with defined chemical structures generally exhibit poor absorption spectra,herein we first introduced narrow bandgap Y-series acceptors into the molecular skeleton of single-component materials,and designed two molecular dyads,SM-Et-1Y and SM-Et-2Y.The optical bandgaps(E_g~(opt)s)of the two dyads are 1.364 and 1.361 eV,respectively,which are much smaller than those of previously reported single-component molecules.Consequently,the SM-Et-2Y-based single-component OSCs(SCOSCs)showed a power conversion efficiency(PCE)of 5.07%,superior to SM-Et-1Y(2.53%),which is one of the highest PCEs reported for SCOSCs to date.Moreover,both SM-Et-1Y-and SM-Et-2Y-based devices exhibited excellent photo-stability,retaining over 90%of their initial performance after 250 h of continuous illumination.Our results provide a deeper understanding of the molecular backbone and a guiding principle for the rational design or selection of non-fullerene single-component materials with suitable donor/acceptor ratios.展开更多
We test whether differences in the background characteristics of firms’chairperson and CEO can reduce management agency costs.We find that when the chairperson is older,has a higher level of education,and has more ov...We test whether differences in the background characteristics of firms’chairperson and CEO can reduce management agency costs.We find that when the chairperson is older,has a higher level of education,and has more overseas experience than the CEO,the management agency costs will be lower.A series of robustness tests do not change our conclusions.In further analysis,we find that the negative relationship between the two is more significant for SOEs or firms experiencing fierce market competition.Finally,we also find that the chairman-CEO’s vertical dyad background characteristics differences can help to improve firm performance.Our study provides theoretical and practical implications for companies on how to best configure their top management team.展开更多
Three novel symmetrical 4.4＇-difluoro-4-bora-3a,4a-diaza-sindacene（BODIPY） derivatives were synthesized via a general and efficient protocol. These BODIPY dyads bear a diverse aryl linker bridge in the middle and t...Three novel symmetrical 4.4＇-difluoro-4-bora-3a,4a-diaza-sindacene（BODIPY） derivatives were synthesized via a general and efficient protocol. These BODIPY dyads bear a diverse aryl linker bridge in the middle and two BODIPY units at the termini. The photophysical properties of these dyads were investigated by ultravioletvisible（UV-Vis） absorption and emission spectroscopy. And their electrochemical properties were studied by cyclic voltammetry. The absorption of these dyads showed slightly blue shift and the intramolecular charge transfer（ICT） state under,vent ultrafast direct surface crossing to the ground state with high degree of rotational freedom. The results will be useful for the further functionalization of these novel symmetrical BODIPY derivatives.展开更多
ELECTRON transfer plays a crucial role in energy transformation of natural biological systemssuch as the photosynthetic process by which plants convert solar energy into chemical energy.This is achieved in photosynthe...ELECTRON transfer plays a crucial role in energy transformation of natural biological systemssuch as the photosynthetic process by which plants convert solar energy into chemical energy.This is achieved in photosynthesis by a series of electron transfers which occur after light is ab-sorbed. Among the various factors which influence the efficiency of electron transfer struc-tural effect is one of the important features to be considered. In recent years, numerous syn-thetic model dyads in which electron donor and electron acceptor are covalently linked by dif-ferent spacers have been designed and synthesized in an effort to understand how the展开更多
Methyl 9 ethylenedioxpyropheophorbide d was prepared from methyl pyropheophorbide a by protection of cyclic ketone with ethylene glycol, and oxidation with OsO 4 in vinyl group at 2 position. The terminal alky...Methyl 9 ethylenedioxpyropheophorbide d was prepared from methyl pyropheophorbide a by protection of cyclic ketone with ethylene glycol, and oxidation with OsO 4 in vinyl group at 2 position. The terminal alkyne was introduced into chlorin chromophore by Grignard reaction, and the enediyne moiety was constructed by a palladium catalyzed coupling reaction with (Z) chloroenynes.展开更多
A series oftri（alkoxyl）benzene-fullerene dyads（PCBB-Cn, n=4, 6, 8, 10, 12） with varied tri（alkoxyl） chain lengths was designed, synthesized and used as acceptor materials in polymer solar cells（PSCs）. The five...A series oftri（alkoxyl）benzene-fullerene dyads（PCBB-Cn, n=4, 6, 8, 10, 12） with varied tri（alkoxyl） chain lengths was designed, synthesized and used as acceptor materials in polymer solar cells（PSCs）. The five fullerene dyads possess similar absorption spectra in dilute solution, decreased glass-transition temperature（Tg） and gradually elevated lowest unoccupied molecular orbital（LUMO） energy levels from -3.87 eV to -3.73 eV with the increase of the alkoxy chain length. In the fabrication of PSCs with poly（3-hexylthiophene）（P3HT） as donor and the fullerene dyads as acceptor, PCBB-Cn with longer tri（alkoxyl） chains and lower Tg can induce crystalline structure of P3HT during spin-coating the photoactive layer at room temperature and form nanoscale phase separated interpenetrating network of P3HT：PCBB-Cn blend films, which results in the improvement of photovoltaic performance of PSCs. A power conversion efficiency of 3.03% for the PSCs based on P3HT：PCBB-C10 was obtained without thermal annealing or solvent annealing. The thermal and solvent annealing-free fabrication using the fullerene dyads as acceptor is very important for the roll to roll production of PSCs with flexible large area.展开更多
The molecular aggregation state of a porphyrin-perylenediimide dyad can be changed by treating with trifluoroacetic acid. Transmittance electron microscopy (TEM) images revealed that lamella micro- structures were for...The molecular aggregation state of a porphyrin-perylenediimide dyad can be changed by treating with trifluoroacetic acid. Transmittance electron microscopy (TEM) images revealed that lamella micro- structures were formed when the dyad precipitated from neutral solvent, but spherical nano-particles were obtained when precipitating from acidic solution. X-ray diffraction patterns showed that the la- mella microstructures and the nanoparticles were polycrystalline and amorphous solids, respectively. By using rational perylenediimide and porphyrin as reference compounds, careful analyses on the UV-visible spectra of the dyad and the references under different conditions were conducted and the results demonstrated that both the porphyrin and perylendiimide subunits of the dyad took J-aggregation in neutral solvent, but after being treated with trifluoroacetic acid and chloroform solu- tion, the perylenediimide subunit changed to an H-aggregation while the porphyrin subunits changed to a random packing mode.展开更多
文摘Dyad and triad census summarize much of the network level structural information of a given directed network. They have been found very useful in analyzing structural properties of social networks. This study aims to explore crisis communication network by following dyad and triad census analysis approach to investigate the association of microlevel communication patterns with organizational crisis. This study further tests hypothesis related to the process of data generation and tendency of the structural pattern of transitivity using dyad and triad census output. The changing communication network at Enron Corporation during the period of its crisis is analyzed in this study. Significant differences in the presence of different isomorphism classes or microlevel patterns of both dyad and triad census are noticed in crisis and non-crisis period network of Enron email corpus. It is also noticed that crisis communication network shows more transitivity compared to the non-crisis communication network.
文摘A new copper phthalocyanine-fullerene dyad (CuPc-C-60) was synthesized by Diels-Alder adduct of corresponding CuPc and C-60. The chemical structure of this compound was characterized by elemental analysis, MS, IR, UV-VIS and NMR.
文摘In order to harness wind energy with high coefficients, horizontal axis wind turbines (HAWT), like propeller-type wind turbines, have an advantage in terms of practical utilization because of their scale merit. However, large size and high tip-speed ratio are inherently related to material strength problems and low frequency noise emissions to the environment. In contrast to HAWT, we will discuss a flapping-type turbine driven at low speed. The flapping turbine works using lift force like the HAWT, but employs a new wind turbine concept in the present report. The concept involves the unique flapping motion of a wind blade mounted on a Chebyshev-dyad linkage by which the wing transforms wind energy into mechanical rotation. Both static and dynamic numerical estimates are developed to optimize all fundamental parameters of this linkage in order to obtain the desired torque. In this paper, the results of primitive optimization for determining the fundamental characteristics of motion and the trajectory of the wind turbine blade are demonstrated in order to obtain smooth rotation of the generator-driving shaft. It is also shown that the present turbine can be driven at low speed with a suitable energy conversion rate. Moreover, the practicality of operating slow flapping-type wind turbines is demonstrated, focusing on usage near residential areas or, e.g., on rooftops owing to lower noise. The feasibility of “figure eight” trajectory diversity is discussed along with geometrical parameters. Assuming one-blade motion with a variable trajectory for optimization, the smooth motion and required torque at slow rotation speeds are studied.
基金This work was supported by the National Natural Science Foundation of China （No.10374040, No.20703064, and No.10505001） and the Postdoctoral Science Foundation of China （No.20060390017）.
基金Beijing Natural Science Foundation,Grant/Award Number:JQ210065NSFC,Grant/Award Numbers:52073016,92163128+4 种基金Fundamental Research Funds for the Central Universities,Grant/Award Numbers:buctrc201828,XK1802-2The opening Foundation of State Key Laboratory of Organic-Inorganic Composites,Beijing University of Chemical Technology,Grant/Award Number:oic-202201006Jiangxi Provincial Department of Science and Technology,Grant/Award Numbers:20202ACBL213004,20212BCJ23035,jxsq2019102004,20203BBE53062Jiangxi Academy of Sciences,Grant/Award Numbers:2021YSBG22034,2021YSBG22033,2020-YZD-3Australian Research Council,Grant/Award Number:FT180100594。
文摘The molecular orientations of conjugated materials on the substrate mainly include edge-on,face-on,and end-on.Edge-on and face-on orientations have been widely observed,while end-on orientation has been rarely reported.Since in organic solar cells(OSCs)charge transport is along the vertical direction,end-on orientation with conjugated backbones perpendicular to the substrate is recognized as the ideal microstructure for OSCs.In this work,we for the first time obtained the preferential end-on orientation in a conjugated molecular dyad that contains a conjugated backbone as donor and perylene bisimide side units as acceptor.This was realized by introducing a fused-ring structure to replace linear terthiophenes with conjugated backbones,yielding F-MDPBI and L-MDPBI respectively.Surprisingly,a shifting trend of the molecular orientation from dominating edge-on in L-MDPBI to preferential end-on in F-MDPBI was observed.As a consequence,vertical charge carrier mobilities in F-MDPBI are one order of magnitude higher than those with preferential edge-on orientation,so single-component OSCs based on this molecular dyad as a single photoactive layer provided a power conversion efficiency of 4.89% compared to 1.70% based on L-MDPBI with preferential edge-on orientation.
基金supported by the National Natural Science Foundation of China(52061135206,22279094)the Fundamental Research Funds for the Central Universities。
文摘The performance of organic solar cells(OSCs)is mainly related to the bulk heterojunction(BHJ)microstructure of specific active layer systems,which is often in a metastable state.A promising strategy to address the abovementioned shortcomings of BHJs is to develop single-component active layer materials.Owing to the single-component small molecule materials with defined chemical structures generally exhibit poor absorption spectra,herein we first introduced narrow bandgap Y-series acceptors into the molecular skeleton of single-component materials,and designed two molecular dyads,SM-Et-1Y and SM-Et-2Y.The optical bandgaps(E_g~(opt)s)of the two dyads are 1.364 and 1.361 eV,respectively,which are much smaller than those of previously reported single-component molecules.Consequently,the SM-Et-2Y-based single-component OSCs(SCOSCs)showed a power conversion efficiency(PCE)of 5.07%,superior to SM-Et-1Y(2.53%),which is one of the highest PCEs reported for SCOSCs to date.Moreover,both SM-Et-1Y-and SM-Et-2Y-based devices exhibited excellent photo-stability,retaining over 90%of their initial performance after 250 h of continuous illumination.Our results provide a deeper understanding of the molecular backbone and a guiding principle for the rational design or selection of non-fullerene single-component materials with suitable donor/acceptor ratios.
基金supported by National Natural Science Foundation of China[Grant No 72072060,71602059]Soft Science Research Project of Guangdong Province,China[grant numbers2020A1010020004]+1 种基金“13th Five-year Plan”for the Development of Philosophy and Social Sciences of Guangzhou,Joint construction projects in 2020,China[grant numbers 2020GZGJ11]Fundamental Research Funds for the Central Universities of the South China University of Technology,China[grant numbers XYMS202104]
文摘We test whether differences in the background characteristics of firms’chairperson and CEO can reduce management agency costs.We find that when the chairperson is older,has a higher level of education,and has more overseas experience than the CEO,the management agency costs will be lower.A series of robustness tests do not change our conclusions.In further analysis,we find that the negative relationship between the two is more significant for SOEs or firms experiencing fierce market competition.Finally,we also find that the chairman-CEO’s vertical dyad background characteristics differences can help to improve firm performance.Our study provides theoretical and practical implications for companies on how to best configure their top management team.
基金the National Natural Science Foundation of China
文摘Three novel symmetrical 4.4＇-difluoro-4-bora-3a,4a-diaza-sindacene（BODIPY） derivatives were synthesized via a general and efficient protocol. These BODIPY dyads bear a diverse aryl linker bridge in the middle and two BODIPY units at the termini. The photophysical properties of these dyads were investigated by ultravioletvisible（UV-Vis） absorption and emission spectroscopy. And their electrochemical properties were studied by cyclic voltammetry. The absorption of these dyads showed slightly blue shift and the intramolecular charge transfer（ICT） state under,vent ultrafast direct surface crossing to the ground state with high degree of rotational freedom. The results will be useful for the further functionalization of these novel symmetrical BODIPY derivatives.
文摘ELECTRON transfer plays a crucial role in energy transformation of natural biological systemssuch as the photosynthetic process by which plants convert solar energy into chemical energy.This is achieved in photosynthesis by a series of electron transfers which occur after light is ab-sorbed. Among the various factors which influence the efficiency of electron transfer struc-tural effect is one of the important features to be considered. In recent years, numerous syn-thetic model dyads in which electron donor and electron acceptor are covalently linked by dif-ferent spacers have been designed and synthesized in an effort to understand how the
文摘Methyl 9 ethylenedioxpyropheophorbide d was prepared from methyl pyropheophorbide a by protection of cyclic ketone with ethylene glycol, and oxidation with OsO 4 in vinyl group at 2 position. The terminal alkyne was introduced into chlorin chromophore by Grignard reaction, and the enediyne moiety was constructed by a palladium catalyzed coupling reaction with (Z) chloroenynes.
基金Supported by the National Natural Science Foundation of China（Nos.21204057, 91333204）, the Natural Science Foundation of Jiangsu Province, China（No.BK2012213）, the Priority Academic Development Program of Jiangsu Higher Education Institutions, China and the Soochow University Undergraduate Training Program for Innovation and Entrepreneurship, China（No.2013XjOZO）.
文摘A series oftri（alkoxyl）benzene-fullerene dyads（PCBB-Cn, n=4, 6, 8, 10, 12） with varied tri（alkoxyl） chain lengths was designed, synthesized and used as acceptor materials in polymer solar cells（PSCs）. The five fullerene dyads possess similar absorption spectra in dilute solution, decreased glass-transition temperature（Tg） and gradually elevated lowest unoccupied molecular orbital（LUMO） energy levels from -3.87 eV to -3.73 eV with the increase of the alkoxy chain length. In the fabrication of PSCs with poly（3-hexylthiophene）（P3HT） as donor and the fullerene dyads as acceptor, PCBB-Cn with longer tri（alkoxyl） chains and lower Tg can induce crystalline structure of P3HT during spin-coating the photoactive layer at room temperature and form nanoscale phase separated interpenetrating network of P3HT：PCBB-Cn blend films, which results in the improvement of photovoltaic performance of PSCs. A power conversion efficiency of 3.03% for the PSCs based on P3HT：PCBB-C10 was obtained without thermal annealing or solvent annealing. The thermal and solvent annealing-free fabrication using the fullerene dyads as acceptor is very important for the roll to roll production of PSCs with flexible large area.
基金the National Natural Science Foundation of China (Grant Nos. 50573065 and 50573019)the Natural Science Foundation of Zhejiang Province of China (Grant No. Z406018)
文摘The molecular aggregation state of a porphyrin-perylenediimide dyad can be changed by treating with trifluoroacetic acid. Transmittance electron microscopy (TEM) images revealed that lamella micro- structures were formed when the dyad precipitated from neutral solvent, but spherical nano-particles were obtained when precipitating from acidic solution. X-ray diffraction patterns showed that the la- mella microstructures and the nanoparticles were polycrystalline and amorphous solids, respectively. By using rational perylenediimide and porphyrin as reference compounds, careful analyses on the UV-visible spectra of the dyad and the references under different conditions were conducted and the results demonstrated that both the porphyrin and perylendiimide subunits of the dyad took J-aggregation in neutral solvent, but after being treated with trifluoroacetic acid and chloroform solu- tion, the perylenediimide subunit changed to an H-aggregation while the porphyrin subunits changed to a random packing mode.
