Aiming at mitigating the high risks associated with conventional explosive blasting,this study developed a safe directional fracturing technique,i.e.instantaneous expansion with a single fracture(IESF),using a coal-ba...Aiming at mitigating the high risks associated with conventional explosive blasting,this study developed a safe directional fracturing technique,i.e.instantaneous expansion with a single fracture(IESF),using a coal-based solid waste expanding agent.First,the mechanism of directional fracturing blasting by the IESF was analyzed,and the criterion of directional crack initiation was established.On this basis,laboratory experiments and numerical simulations were conducted to systematically evaluate the directional fracturing blasting performance of the IESF.The results indicate that the IESF presents an excellent directional fracturing effect,with average surface undulation differences ranging from 8.1 mm to 22.7 mm on the fracture surfaces.Moreover,during concrete fracturing tests,the stresses and strains in the fracturing direction are measured to be 2.16-3.71 times and 8 times larger than those in the nonfracturing direction,respectively.Finally,the IESF technique was implemented for no-pillar mining with gob-side entry retaining through roof cutting and pressure relief in an underground coal mine.The IESF technique effectively created directional cracks in the roof without causing severe roadway deformation,achieving an average cutting rate and maximum roadway deformation of 94%and 197 mm,respectively.These on-site test results verified its excellent directional rock fracturing performance.The IESF technique,which is safe,efficient,and green,has considerable application prospects in the field of rock mechanics and engineering.展开更多
Longitudinal seismic performance is a critical aspect to be considered during the tunnel design process,in addition to cross-sectional considerations.The present study proposed using a laminated shear energy dissipati...Longitudinal seismic performance is a critical aspect to be considered during the tunnel design process,in addition to cross-sectional considerations.The present study proposed using a laminated shear energy dissipation(LSED)structure to achieve effective longitudinal seismic design.The proposed structure consists of thin steel plates and alternately bonded layers of rubber,which can be installed around the periphery of the secondary lining.This configuration guarantees that the tunnels will exhibit optimal axial deformation capacity and robust rigid resistance to circumferential compression from the surrounding rock.To evaluate the impact of the LSED structure on the longitudinal seismic performance of the tunnel,a fine numerical model of the LSED structureetunnel liningesurrounding rock system was developed using finite element simulation.The evaluation criteria include maximum principal stress and strain energy.The seismic response of the tunnel with the LSED structure exhibited a notable reduction of over 40%in terms of seismic attenuation rate when subjected to the Trinidad seismic wave compared to the tunnel without the LSED structure.Furthermore,the aseismic mechanism of the proposed LSED structure is discussed,considering both internal factors such as the rubber shear modulus,steel plate dimensions,and number and location of structures,and external influencing factors such as seismic wave parameters and surrounding rock quality.Meanwhile,the effectiveness of the tunnel with the LSED structure has been quantitatively demonstrated in terms of seismic fragility curves.展开更多
Accurate seismic assessment and proper aseismic design of underground structures require a comprehensive understanding of seismic performance and response of underground structures under earthquake force.In order to u...Accurate seismic assessment and proper aseismic design of underground structures require a comprehensive understanding of seismic performance and response of underground structures under earthquake force.In order to understand the seismic behavior of tunnels during an earthquake,a wide collection of case histories has been reviewed from the available literature with respect to damage classification,to discuss the possible causes of damage,such as earthquake parameters,structural form and geological conditions.In addition,a case of Tawarayama tunnel subjected to the 2016 Kumamoto earthquake is studied.Discussion on the possible influence factors aims at improving the performancebased aseismic design of tunnels.Finally,restoration design criterion and methods are presented taking Tawarayama tunnel as an example.展开更多
Transition-metal based M-N_4/C catalysts are appealing for electrocatalytic oxygen reduction reaction(ORR) and oxygen evolution reaction(OER). Employing model catalysts, which have well-defined molecular structures an...Transition-metal based M-N_4/C catalysts are appealing for electrocatalytic oxygen reduction reaction(ORR) and oxygen evolution reaction(OER). Employing model catalysts, which have well-defined molecular structures and coordination environments, to investigate electrocatalytic performance of M-N_4/C sites for ORR and OER is of fundamental significance. Herein, we reported the use of Co tetra(phenyl)porphyrin 1 and Co tetra(pentafluorophenyl)porphyrin 2 as models to probe the role of Co-N_4/C sites for oxygen electrocatalysis. We showed that Co porphyrin 1 is more efficient than its structural analogue 2 for oxygen electrocatalysis in alkaline aqueous solutions, indicating that the electronrich Co-N_4/C site is more favored when noncovalently adsorbed on carbon supports. This work inspires rational design of reaction-oriented catalysts for sustainable energy storage and conversion technologies.展开更多
Spatiotemporal dynamic vegetation changes affect global climate change,energy balances and the hydrological cycle.Predicting these dynamics over a long time series is important for the study and analysis of global env...Spatiotemporal dynamic vegetation changes affect global climate change,energy balances and the hydrological cycle.Predicting these dynamics over a long time series is important for the study and analysis of global environmental change.Based on leaf area index(LAI),climate,and radiation flux data of past and future scenarios,this study looked at historical dynamic changes in global vegetation LAI,and proposed a coupled multiple linear regression and improved gray model(CMLRIGM)to predict future global LAI.The results show that CMLRIGM predictions are more accurate than results predicted by the multiple linear regression(MLR)model or the improved gray model(IGM)alone.This coupled model can effectively resolve the problem posed by the underestimation of annual average of global vegetation LAI predicted by MLR and the overestimate predicted by IGM.From 1981 to 2018,the annual average of LAI in most areas covered by global vegetation(71.4%)showed an increase with a growth rate of 0.0028 a-1;of this area,significant increases occurred in 34.42%of the total area.From 2016 to 2060,the CMLRIGM model has predicted that the annual average global vegetation LAI will increase,accounting for approximately 68.5%of the global vegetation coverage,with a growth rate of 0.004 a-1.The growth rate will increase in the future scenario,and it may be related to the driving factors of the high emission scenario used in this study.This research may provide a basis for simulating spatiotemporal dynamic changes in global vegetation conditions over a long time series.展开更多
High temperature stress (HT) significantly reduces maize yield by impairing starch accumulation in kernels.However,the mechanism by which HT affects starch synthesis remains controversial-whether through reduced assim...High temperature stress (HT) significantly reduces maize yield by impairing starch accumulation in kernels.However,the mechanism by which HT affects starch synthesis remains controversial-whether through reduced assimilate supply or direct inhibition on kernel metabolism.To clarify these mechanisms,a heat-sensitive maize hybrid,Xianyu 335 (XY),was exposed to 30℃/20℃ (maximum/minimum temperature,control) and 40℃/30℃ for seven consecutive days during the seed setting stage.Synchronous pollination (SP),apical pollination (AP),and shading treatments were applied to manipulate the inherent source–sink ratio in maize plants.Results showed that apical kernel weight decreased by 11.9%under 40℃ in the SP treatment.The ^(13)C content,starch accumulation,and cell-wall invertase (CWIN) activity also declined by 15.9,36.7,and 16.4%,respectively,under HT.In the shading treatment,40℃/30℃ caused even greater reductions in^(13)C content,starch accumulation,and CWIN activity due to diminished assimilate supply.Conversely,in the AP treatment,starch content and CWIN activity increased by 22.0 and 18.5%,respectively,under 40℃/30℃,resulting in kernel weight and ^(13)C content similar to those in SP and shading treatments regardless of temperature.Consistent with apical kernels under AP,HT did not negatively affect middle kernels in either SP or shading treatments,as kernel weight and starch content remained unchanged under HT.Although all kernels were exposed to the same HT or control environment,their responses varied a lot.The impaired starch synthesis in apical kernels under HT was rescued by increasing carbon supply via AP treatment.The contrasting performance among middle kernels,apical kernels under AP,and apical kernels under SP or shading indicates that reduced carbon supply is a critical factor underlying inhibited starch accumulation.Our findings provide a theoretical basis for further understanding kernel abortion under HT.展开更多
Introduction The Kasabach–Merritt phenomenon(KMP)is a severe complication of kaposiform hemangioendothelioma(KHE).The risk factors for KMP need further investigation.Methods The medical records of patients with KHE w...Introduction The Kasabach–Merritt phenomenon(KMP)is a severe complication of kaposiform hemangioendothelioma(KHE).The risk factors for KMP need further investigation.Methods The medical records of patients with KHE were reviewed.Univariate and multivariate logistic regression models were used for the risk factors for KMP,and the area under the receiver operator characteristic(ROC)curve was used to assess the predictive power of risk factors.Results A total of 338 patients with KHE were enrolled.The incidence of KMP was 45.9%.Age of onset(P<0.001,odds ratio[OR]0.939;95%confidence interval[CI]0.914–0.966),lesion size(P<0.001,OR 1.944;95%CI 1.646–2.296),mixed type(P=0.030,OR 2.428;95%CI 1.092–5.397),deep type(P=0.010,OR 4.006;95%CI 1.389–11.556),and mediastinal or retroperitoneal lesion location(P=0.019,OR 11.864;95%CI 1.497–94.003)were correlated with KMP occurrence through multivariate logistic regression.ROC curve analysis revealed that the optimal cutoffs were 4.75 months for the age of onset(P<0.001,OR 7.206,95%CI 4.073–12.749)and a lesion diameter of 5.35 cm(P<0.001,OR 11.817,95%CI 7.084–19.714).Bounded by a lesion size of 5.35 cm,we found significant differences in tumor morphology,age of onset,treatments,and hematological parameters.Using an onset age of 4.75 months as a cutoff,we found significant differences in tumor morphology,lesion size,hematological parameters,and prognosis.Conclusion For KHE patients with an onset age<4.75 months and/or lesion diameter>5.35 cm,clinicians should be wary of the occurrence of KMP.Active management is recommended to improve the prognosis.展开更多
The stimulus-responsive room-temperature phosphorescence(RTP)materials have become an increasingly significant topic in the fields of bioimaging,sensing,and anticounterfeiting.However,this kind of materials is scarce ...The stimulus-responsive room-temperature phosphorescence(RTP)materials have become an increasingly significant topic in the fields of bioimaging,sensing,and anticounterfeiting.However,this kind of materials is scarce to date,especially for the ones with delicate stimulus-responsive behavior.Herein,a universal strategy for multilevel thermal erasure of RTP via chromatographic separation of host-vip doping RTP systems is proposed.The tunable host-vip systems,matrix materials,heating temperature,and time are demonstrated to allow precise six-level data encryption,QR code encryption,and thermochromic phosphorescence encryption.Mechanistic study reveals that the thermal-responsive property might be attributed to molecular thermal motion and the separation effect of the silica gel,which provides expanded applications of host-vip RTP materials such as cold chain break detection.This work offers a simple yet universal way to construct advanced responsive RTP materials.展开更多
Organic and inorganic clusteroluminescence have attracted great attention while the underlying mechanisms is still not well understood.Here,we employed a series of ancient inorganic complexes platinocyanides with aggr...Organic and inorganic clusteroluminescence have attracted great attention while the underlying mechanisms is still not well understood.Here,we employed a series of ancient inorganic complexes platinocyanides with aggregation-induced emission property to elucidate the mechanism of clusteroluminescence including how does the chromophore form and how does the solid structures influence the luminescence behaviors.The results indicate that the isolated platinocyanide cannot work as a chromophore to emit visible light,while their clusterization at aggregate state can trigger the d-orbitals coupling of the platinum atoms to facilitate the electron exchange and delocalization to form a new chromophore to emit visible light.Furthermore,the counter ions and H2O ligands help to rigidify the three-dimensional network structure of the platinocyanides to suppress the excited state nonradiative decay,resulting in the high quantum yield of up to 96%.This work fundamentally helps understanding both the organic and inorganic clusteroluminescence phenomenon.展开更多
Many aggregation-induced emission(AIE)systems exhibit broad and structureless luminescence emission spectra resembling the Gaussian distribution,which is likely due to kinetically locked molecular conformers in the co...Many aggregation-induced emission(AIE)systems exhibit broad and structureless luminescence emission spectra resembling the Gaussian distribution,which is likely due to kinetically locked molecular conformers in the condensed phase.To verify the hypothesis,a series of tetraphenylethene(TPE)derivatives are synthesized and characterized as aqueous nanoparticle suspensions.It is found that the unsubstituted TPE exhibits reduced fluorescence intensity accompanied by a blueshift of the emission maximum,after the temperature of the aqueous suspension is elevated and cooled to room temperature again.For a naphthalimide-substituted TPE compound,thermal treatment of the AIE aqueous suspension results in complete,irreversible aggregation-caused quenching(ACQ)of fluorescence,which can be restored by a redissolving-precipitation process of thermally treated aggregates.The phenomenon is ascribed as a relative population shift of a kinetic AIE(k-AIE)state to a thermodynamic AIE(t-AIE)or ACQ state,evidenced by differential scanning calorimetry,dynamic light scattering,and scanning electron microscopy.The phenomenon may be universal for many other AIE systems and could be explored as stimuli-responsive materials.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52404155)State Key Laboratory of Mining Disaster Prevention and Control(Shandong University of Science and Technology)+1 种基金Ministry of Education(Grant No.JMDPC202402)supported by the opening project of State Key Laboratory of Explosion Science and Safety Protection(Beijing Institute of Technology).The opening project number is KFJJ24-20M.
文摘Aiming at mitigating the high risks associated with conventional explosive blasting,this study developed a safe directional fracturing technique,i.e.instantaneous expansion with a single fracture(IESF),using a coal-based solid waste expanding agent.First,the mechanism of directional fracturing blasting by the IESF was analyzed,and the criterion of directional crack initiation was established.On this basis,laboratory experiments and numerical simulations were conducted to systematically evaluate the directional fracturing blasting performance of the IESF.The results indicate that the IESF presents an excellent directional fracturing effect,with average surface undulation differences ranging from 8.1 mm to 22.7 mm on the fracture surfaces.Moreover,during concrete fracturing tests,the stresses and strains in the fracturing direction are measured to be 2.16-3.71 times and 8 times larger than those in the nonfracturing direction,respectively.Finally,the IESF technique was implemented for no-pillar mining with gob-side entry retaining through roof cutting and pressure relief in an underground coal mine.The IESF technique effectively created directional cracks in the roof without causing severe roadway deformation,achieving an average cutting rate and maximum roadway deformation of 94%and 197 mm,respectively.These on-site test results verified its excellent directional rock fracturing performance.The IESF technique,which is safe,efficient,and green,has considerable application prospects in the field of rock mechanics and engineering.
基金supported by the National Natural Science Foundation of China(Grant No.52109132)the Shandong Provincial Natural Science Foundation(Grant No.ZR2020QE270).
文摘Longitudinal seismic performance is a critical aspect to be considered during the tunnel design process,in addition to cross-sectional considerations.The present study proposed using a laminated shear energy dissipation(LSED)structure to achieve effective longitudinal seismic design.The proposed structure consists of thin steel plates and alternately bonded layers of rubber,which can be installed around the periphery of the secondary lining.This configuration guarantees that the tunnels will exhibit optimal axial deformation capacity and robust rigid resistance to circumferential compression from the surrounding rock.To evaluate the impact of the LSED structure on the longitudinal seismic performance of the tunnel,a fine numerical model of the LSED structureetunnel liningesurrounding rock system was developed using finite element simulation.The evaluation criteria include maximum principal stress and strain energy.The seismic response of the tunnel with the LSED structure exhibited a notable reduction of over 40%in terms of seismic attenuation rate when subjected to the Trinidad seismic wave compared to the tunnel without the LSED structure.Furthermore,the aseismic mechanism of the proposed LSED structure is discussed,considering both internal factors such as the rubber shear modulus,steel plate dimensions,and number and location of structures,and external influencing factors such as seismic wave parameters and surrounding rock quality.Meanwhile,the effectiveness of the tunnel with the LSED structure has been quantitatively demonstrated in terms of seismic fragility curves.
基金funded by Japan Society for the Promotion of Science(JSPS)Grant-in-Aid for Scientific Research(Grant No.17H03506)JSPS-NSFC Bilateral Joint Research Project,Japan。
文摘Accurate seismic assessment and proper aseismic design of underground structures require a comprehensive understanding of seismic performance and response of underground structures under earthquake force.In order to understand the seismic behavior of tunnels during an earthquake,a wide collection of case histories has been reviewed from the available literature with respect to damage classification,to discuss the possible causes of damage,such as earthquake parameters,structural form and geological conditions.In addition,a case of Tawarayama tunnel subjected to the 2016 Kumamoto earthquake is studied.Discussion on the possible influence factors aims at improving the performancebased aseismic design of tunnels.Finally,restoration design criterion and methods are presented taking Tawarayama tunnel as an example.
基金supported by the "Thousand Talents Program" of China, the Fok Ying-Tong Education Foundation for Outstanding Young Teachers in University, the National Natural Science Foundation of China (21573139, 21773146, 21902099, and 21905167)theChinaPostdoctoralScienceFoundation (2019M650232)+2 种基金the Fundamental Research Funds for the Central Universities (GK202003025)the Research Funds of Shaanxi Normal Universitythe Opening Fund of State Key Laboratory of Heavy Oil Processing。
文摘Transition-metal based M-N_4/C catalysts are appealing for electrocatalytic oxygen reduction reaction(ORR) and oxygen evolution reaction(OER). Employing model catalysts, which have well-defined molecular structures and coordination environments, to investigate electrocatalytic performance of M-N_4/C sites for ORR and OER is of fundamental significance. Herein, we reported the use of Co tetra(phenyl)porphyrin 1 and Co tetra(pentafluorophenyl)porphyrin 2 as models to probe the role of Co-N_4/C sites for oxygen electrocatalysis. We showed that Co porphyrin 1 is more efficient than its structural analogue 2 for oxygen electrocatalysis in alkaline aqueous solutions, indicating that the electronrich Co-N_4/C site is more favored when noncovalently adsorbed on carbon supports. This work inspires rational design of reaction-oriented catalysts for sustainable energy storage and conversion technologies.
基金supported by the Beijing Natural Science Foundation(8192037)Key Research and Development Program of Guangxi(AB18050014)the National Natural Science Foundation of China(41701391)。
文摘Spatiotemporal dynamic vegetation changes affect global climate change,energy balances and the hydrological cycle.Predicting these dynamics over a long time series is important for the study and analysis of global environmental change.Based on leaf area index(LAI),climate,and radiation flux data of past and future scenarios,this study looked at historical dynamic changes in global vegetation LAI,and proposed a coupled multiple linear regression and improved gray model(CMLRIGM)to predict future global LAI.The results show that CMLRIGM predictions are more accurate than results predicted by the multiple linear regression(MLR)model or the improved gray model(IGM)alone.This coupled model can effectively resolve the problem posed by the underestimation of annual average of global vegetation LAI predicted by MLR and the overestimate predicted by IGM.From 1981 to 2018,the annual average of LAI in most areas covered by global vegetation(71.4%)showed an increase with a growth rate of 0.0028 a-1;of this area,significant increases occurred in 34.42%of the total area.From 2016 to 2060,the CMLRIGM model has predicted that the annual average global vegetation LAI will increase,accounting for approximately 68.5%of the global vegetation coverage,with a growth rate of 0.004 a-1.The growth rate will increase in the future scenario,and it may be related to the driving factors of the high emission scenario used in this study.This research may provide a basis for simulating spatiotemporal dynamic changes in global vegetation conditions over a long time series.
基金financially supported by the National Natural Science Foundation of China (32071978)the National Key Research and Development Program of China (2022YFD2300901 and 2022YFD2300905)。
文摘High temperature stress (HT) significantly reduces maize yield by impairing starch accumulation in kernels.However,the mechanism by which HT affects starch synthesis remains controversial-whether through reduced assimilate supply or direct inhibition on kernel metabolism.To clarify these mechanisms,a heat-sensitive maize hybrid,Xianyu 335 (XY),was exposed to 30℃/20℃ (maximum/minimum temperature,control) and 40℃/30℃ for seven consecutive days during the seed setting stage.Synchronous pollination (SP),apical pollination (AP),and shading treatments were applied to manipulate the inherent source–sink ratio in maize plants.Results showed that apical kernel weight decreased by 11.9%under 40℃ in the SP treatment.The ^(13)C content,starch accumulation,and cell-wall invertase (CWIN) activity also declined by 15.9,36.7,and 16.4%,respectively,under HT.In the shading treatment,40℃/30℃ caused even greater reductions in^(13)C content,starch accumulation,and CWIN activity due to diminished assimilate supply.Conversely,in the AP treatment,starch content and CWIN activity increased by 22.0 and 18.5%,respectively,under 40℃/30℃,resulting in kernel weight and ^(13)C content similar to those in SP and shading treatments regardless of temperature.Consistent with apical kernels under AP,HT did not negatively affect middle kernels in either SP or shading treatments,as kernel weight and starch content remained unchanged under HT.Although all kernels were exposed to the same HT or control environment,their responses varied a lot.The impaired starch synthesis in apical kernels under HT was rescued by increasing carbon supply via AP treatment.The contrasting performance among middle kernels,apical kernels under AP,and apical kernels under SP or shading indicates that reduced carbon supply is a critical factor underlying inhibited starch accumulation.Our findings provide a theoretical basis for further understanding kernel abortion under HT.
基金supported by the National Natural Science Foundation of China(Grant No.82273556)the Key Project in the Science&Technology Program of Sichuan Province(Grants No.2022YFS0233,2022YFS0225,and 2022NSFSC1480)+3 种基金the Project of‘0 to 1’of Sichuan University(Grant No.2022SCUH0033)the MedX Center for Informatics Funding Project(Grant No.YGJC004)the 1·3·5 Project for Disciplines of Excellence-Clinical Research Incubation Project of West China Hospital of Sichuan University(Grants No.2019HXFH056 and 2020HXFH048)the 1·3·5 Project for Disciplines of Excellence-Clinical Research Interdisciplinary Innovation Project of West China Hospital of Sichuan University(Grant No.ZYJC21060).
文摘Introduction The Kasabach–Merritt phenomenon(KMP)is a severe complication of kaposiform hemangioendothelioma(KHE).The risk factors for KMP need further investigation.Methods The medical records of patients with KHE were reviewed.Univariate and multivariate logistic regression models were used for the risk factors for KMP,and the area under the receiver operator characteristic(ROC)curve was used to assess the predictive power of risk factors.Results A total of 338 patients with KHE were enrolled.The incidence of KMP was 45.9%.Age of onset(P<0.001,odds ratio[OR]0.939;95%confidence interval[CI]0.914–0.966),lesion size(P<0.001,OR 1.944;95%CI 1.646–2.296),mixed type(P=0.030,OR 2.428;95%CI 1.092–5.397),deep type(P=0.010,OR 4.006;95%CI 1.389–11.556),and mediastinal or retroperitoneal lesion location(P=0.019,OR 11.864;95%CI 1.497–94.003)were correlated with KMP occurrence through multivariate logistic regression.ROC curve analysis revealed that the optimal cutoffs were 4.75 months for the age of onset(P<0.001,OR 7.206,95%CI 4.073–12.749)and a lesion diameter of 5.35 cm(P<0.001,OR 11.817,95%CI 7.084–19.714).Bounded by a lesion size of 5.35 cm,we found significant differences in tumor morphology,age of onset,treatments,and hematological parameters.Using an onset age of 4.75 months as a cutoff,we found significant differences in tumor morphology,lesion size,hematological parameters,and prognosis.Conclusion For KHE patients with an onset age<4.75 months and/or lesion diameter>5.35 cm,clinicians should be wary of the occurrence of KMP.Active management is recommended to improve the prognosis.
基金This work was supported by the National Natural Science Foundation of China(Nos.21605125 and 22134005)the Natural Science Foundation of Chongqing(No.cstc2020jcyjmsxmX0992).
文摘The stimulus-responsive room-temperature phosphorescence(RTP)materials have become an increasingly significant topic in the fields of bioimaging,sensing,and anticounterfeiting.However,this kind of materials is scarce to date,especially for the ones with delicate stimulus-responsive behavior.Herein,a universal strategy for multilevel thermal erasure of RTP via chromatographic separation of host-vip doping RTP systems is proposed.The tunable host-vip systems,matrix materials,heating temperature,and time are demonstrated to allow precise six-level data encryption,QR code encryption,and thermochromic phosphorescence encryption.Mechanistic study reveals that the thermal-responsive property might be attributed to molecular thermal motion and the separation effect of the silica gel,which provides expanded applications of host-vip RTP materials such as cold chain break detection.This work offers a simple yet universal way to construct advanced responsive RTP materials.
基金National Natural Science Foundation of China,Grant/Award Numbers:21788102,52003228Science and Technology Plan of Shenzhen,Grant/Award Number:JCYJ20180306174910791+2 种基金Natural Science Foundation of Guangdong Province,Grant/Award Number:2019B121205002Research Grants Council of Hong Kong,Grant/Award Numbers:N_HKUT609/19,16305518,A-HKUST605/16,C6009-17GInnovation and Technology Commission,Grant/Award Numbers:ITC-CNERC14SC01,ITCPD/17-9。
文摘Organic and inorganic clusteroluminescence have attracted great attention while the underlying mechanisms is still not well understood.Here,we employed a series of ancient inorganic complexes platinocyanides with aggregation-induced emission property to elucidate the mechanism of clusteroluminescence including how does the chromophore form and how does the solid structures influence the luminescence behaviors.The results indicate that the isolated platinocyanide cannot work as a chromophore to emit visible light,while their clusterization at aggregate state can trigger the d-orbitals coupling of the platinum atoms to facilitate the electron exchange and delocalization to form a new chromophore to emit visible light.Furthermore,the counter ions and H2O ligands help to rigidify the three-dimensional network structure of the platinocyanides to suppress the excited state nonradiative decay,resulting in the high quantum yield of up to 96%.This work fundamentally helps understanding both the organic and inorganic clusteroluminescence phenomenon.
基金National Natural Science Foundation of China,Grant/Award Numbers:21975238,22103077University of Science andTechnology ofChina,Grant/Award Number:KY2340000139。
文摘Many aggregation-induced emission(AIE)systems exhibit broad and structureless luminescence emission spectra resembling the Gaussian distribution,which is likely due to kinetically locked molecular conformers in the condensed phase.To verify the hypothesis,a series of tetraphenylethene(TPE)derivatives are synthesized and characterized as aqueous nanoparticle suspensions.It is found that the unsubstituted TPE exhibits reduced fluorescence intensity accompanied by a blueshift of the emission maximum,after the temperature of the aqueous suspension is elevated and cooled to room temperature again.For a naphthalimide-substituted TPE compound,thermal treatment of the AIE aqueous suspension results in complete,irreversible aggregation-caused quenching(ACQ)of fluorescence,which can be restored by a redissolving-precipitation process of thermally treated aggregates.The phenomenon is ascribed as a relative population shift of a kinetic AIE(k-AIE)state to a thermodynamic AIE(t-AIE)or ACQ state,evidenced by differential scanning calorimetry,dynamic light scattering,and scanning electron microscopy.The phenomenon may be universal for many other AIE systems and could be explored as stimuli-responsive materials.
