In this study,single crystal ZnO microwires(MW)with size of~5.4 mm×30μm are prepared through a chemical vapor deposition technique at high temperature(1200℃).Subsequently,p-type conducting polyaniline(PANI)poly...In this study,single crystal ZnO microwires(MW)with size of~5.4 mm×30μm are prepared through a chemical vapor deposition technique at high temperature(1200℃).Subsequently,p-type conducting polyaniline(PANI)polymers with different conductivities are densely coated on part of the ZnO MW to construct organic/inorganic core-shell heterojunction photodetectors.The hetero-diodes reach an extremely high rectifcation ratio(I_(+3V)/I_(-3V))of 749230,and a maximum rejection ratio(I_(350nm)/I_(dark))of 3556(at-3 V),indicating great potential as rectifed switches.All the heterojunction devices exhibit strong response to ultraviolet(UV)radiation with high response speed.Moreover,the obvious photovoltaic behavior can also be obtained,allowing the device to operate as an independent and stable unit without externally supplied power.Under 0 V bias voltage,the self-powered photodetector shows a maximum responsivity of 0.56 mA W~(-1)and a rapid response speed of 0.11 ms/1.45 ms(rise time/decay time).Finally,a fnite difference time domain(FDTD)simulation is performed to further demonstrate the interaction mechanism between the incident light feld and the hexagonal cavity,which strongly supports the enhancement of the light absorption in whispering-gallery-mode resonator.展开更多
A novel polarization beam splitter(PBS)based on dual-core photonic crystal fiber(DC-PCF)is proposed in this work.The proposed DC-PCF PBS contains two kinds of lattices and three kinds of air holes to form the asymmetr...A novel polarization beam splitter(PBS)based on dual-core photonic crystal fiber(DC-PCF)is proposed in this work.The proposed DC-PCF PBS contains two kinds of lattices and three kinds of air holes to form the asymmetrical elliptic dual-core structure.By using the full-vector finite element method,the propagation characteristics of the proposed DC-PCF PBS are investigated.The simulation results show that the bandwidth of the proposed DC-PCF PBS can reach to 340 nm,which covers the S+C+L+U communication bands,the shortest splitting length is 1.97 mm,and the maximum extinction ratio appears near wavelength 1550 nm.Moreover,the insertion loss of the proposed DC-PCF PBS is very low.It is believed that the proposed DC-PCF PBS has important applications in the field of all-optical communication and network.展开更多
Theδ18O of ice core enclosed gaseous oxygen(δ18Obub)has been widely used for climate reconstruction in polar regions.Yet,less is known about its climatic implication in the mountainous glaciers as the lack of contin...Theδ18O of ice core enclosed gaseous oxygen(δ18Obub)has been widely used for climate reconstruction in polar regions.Yet,less is known about its climatic implication in the mountainous glaciers as the lack of continuous record.Here,we present a long-term,continuousδ18Obub record from the Tanggula glacier in the central Tibetan Plateau(TP).Based on comparisons of its variation with regional climate and glacier changes,we found that there was a good correlation between the variation of theδ18Obub in this alpine ice core and the accumulation and melting of this glacier.The more developed the firn layer on glacier surface,the more positive theδ18Obub.Conversely,the more intense the glacier melting,the more negative theδ18Obub.Combined with the chronology of ice core enclosed gases,the glacier variations since the late Holocene in the central TP were reconstructed.The result showed that there were four accumulation and three deficit periods of glaciers in this region.The strongest glacier accumulation period was 1610-300 B.C.,which corresponds to the Neoglaciation.The most significant melting period was the last 100 years,which corresponds to the recent global warming.The Medieval Warm Period was relatively significant in the central TP.However,during the Little Ice Age,there was no significant glacier accumulation in the central TP,and even short deficit events occurred.Comparisons of the late Holocene glacier variation in the central TP with glacier and climate variations in the TP and the Northern Hemisphere showed that it was closely related to the North Atlantic Oscillation.展开更多
The effects of interfacial strength on fractured microcapsule are investigated numerically. The interaction between crack and microcapsule embedded in mortar matrix is modeled based on cohesive approach. The microcaps...The effects of interfacial strength on fractured microcapsule are investigated numerically. The interaction between crack and microcapsule embedded in mortar matrix is modeled based on cohesive approach. The microcapsules are modelled with variation of core-shell thickness ratio and potential cracks are represented by pre-inserted cohesive elements along the element boundaries of the mortar matrix, microcapsules core, microcapsule shell, and at the interfaces between these phases. Special attention is given to the effects of cohesive fracture on the microcapsule interface, namely fracture strength, on the load carrying capacity and fracture probability of the microcapsule. The effect of fracture properties on microcapsule is found to be significant factor on the load carrying capacity and crack propagation characteristics. Regardless of core-shell thickness ratio of microcapsule, the load carrying capacity of self-healing material under tension increases as interfacial strength of microcapsule shell increases. In addition, given the fixed fracture strength of the interface of microcapsule shell, the higher the ratio core-shell thickness, the higher the probability of microcapsules being fractured.展开更多
基金supported by the National Key Research and Development Program of China(No.2017YFA0204600)the National Natural Science Foundation of China(Nos.61705043,51872050 and 12061131009)。
文摘In this study,single crystal ZnO microwires(MW)with size of~5.4 mm×30μm are prepared through a chemical vapor deposition technique at high temperature(1200℃).Subsequently,p-type conducting polyaniline(PANI)polymers with different conductivities are densely coated on part of the ZnO MW to construct organic/inorganic core-shell heterojunction photodetectors.The hetero-diodes reach an extremely high rectifcation ratio(I_(+3V)/I_(-3V))of 749230,and a maximum rejection ratio(I_(350nm)/I_(dark))of 3556(at-3 V),indicating great potential as rectifed switches.All the heterojunction devices exhibit strong response to ultraviolet(UV)radiation with high response speed.Moreover,the obvious photovoltaic behavior can also be obtained,allowing the device to operate as an independent and stable unit without externally supplied power.Under 0 V bias voltage,the self-powered photodetector shows a maximum responsivity of 0.56 mA W~(-1)and a rapid response speed of 0.11 ms/1.45 ms(rise time/decay time).Finally,a fnite difference time domain(FDTD)simulation is performed to further demonstrate the interaction mechanism between the incident light feld and the hexagonal cavity,which strongly supports the enhancement of the light absorption in whispering-gallery-mode resonator.
基金Project supported by the National Key Research and Development Project of China(Grant No.2019YFB2204001)。
文摘A novel polarization beam splitter(PBS)based on dual-core photonic crystal fiber(DC-PCF)is proposed in this work.The proposed DC-PCF PBS contains two kinds of lattices and three kinds of air holes to form the asymmetrical elliptic dual-core structure.By using the full-vector finite element method,the propagation characteristics of the proposed DC-PCF PBS are investigated.The simulation results show that the bandwidth of the proposed DC-PCF PBS can reach to 340 nm,which covers the S+C+L+U communication bands,the shortest splitting length is 1.97 mm,and the maximum extinction ratio appears near wavelength 1550 nm.Moreover,the insertion loss of the proposed DC-PCF PBS is very low.It is believed that the proposed DC-PCF PBS has important applications in the field of all-optical communication and network.
基金supported by the National Natural Science Foundation of China(Grant No.42271312,41201058)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA20070102)+1 种基金the National Key R&D Program of China(Grant No.2018YFB1307504)the Science and Technology Program of Tibet Autonomous Region of China(Grant No.XZ202101ZD0014G).
文摘Theδ18O of ice core enclosed gaseous oxygen(δ18Obub)has been widely used for climate reconstruction in polar regions.Yet,less is known about its climatic implication in the mountainous glaciers as the lack of continuous record.Here,we present a long-term,continuousδ18Obub record from the Tanggula glacier in the central Tibetan Plateau(TP).Based on comparisons of its variation with regional climate and glacier changes,we found that there was a good correlation between the variation of theδ18Obub in this alpine ice core and the accumulation and melting of this glacier.The more developed the firn layer on glacier surface,the more positive theδ18Obub.Conversely,the more intense the glacier melting,the more negative theδ18Obub.Combined with the chronology of ice core enclosed gases,the glacier variations since the late Holocene in the central TP were reconstructed.The result showed that there were four accumulation and three deficit periods of glaciers in this region.The strongest glacier accumulation period was 1610-300 B.C.,which corresponds to the Neoglaciation.The most significant melting period was the last 100 years,which corresponds to the recent global warming.The Medieval Warm Period was relatively significant in the central TP.However,during the Little Ice Age,there was no significant glacier accumulation in the central TP,and even short deficit events occurred.Comparisons of the late Holocene glacier variation in the central TP with glacier and climate variations in the TP and the Northern Hemisphere showed that it was closely related to the North Atlantic Oscillation.
文摘The effects of interfacial strength on fractured microcapsule are investigated numerically. The interaction between crack and microcapsule embedded in mortar matrix is modeled based on cohesive approach. The microcapsules are modelled with variation of core-shell thickness ratio and potential cracks are represented by pre-inserted cohesive elements along the element boundaries of the mortar matrix, microcapsules core, microcapsule shell, and at the interfaces between these phases. Special attention is given to the effects of cohesive fracture on the microcapsule interface, namely fracture strength, on the load carrying capacity and fracture probability of the microcapsule. The effect of fracture properties on microcapsule is found to be significant factor on the load carrying capacity and crack propagation characteristics. Regardless of core-shell thickness ratio of microcapsule, the load carrying capacity of self-healing material under tension increases as interfacial strength of microcapsule shell increases. In addition, given the fixed fracture strength of the interface of microcapsule shell, the higher the ratio core-shell thickness, the higher the probability of microcapsules being fractured.
