On the basis of the sound velocity measurements of the coral reef core from Nanyong No. 1 Well of Yongshu Reef in the Nansha Islands, the paper studies the relations between the vertical sound velocity transition feat...On the basis of the sound velocity measurements of the coral reef core from Nanyong No. 1 Well of Yongshu Reef in the Nansha Islands, the paper studies the relations between the vertical sound velocity transition features in the coral reef core and the corresponding stratigraphic depositional facies change as well as stratigraphic gap of erosion, analyses the cause of the sound velocity transition, expounds the concrete process of the sea level change resulting in the stratigraphic gap of erosion and facies change in the coral reef and explains the relations between the vertical sound velocity transition in the coral reef core and the corresponding stratigraphic paleoclimate and the sea level change. This study is of important practical value and theoretical significance to the island and reef engineering construction and the acoustic logging for oil exploration in the reef limestone area as well as the paleoceanographic study of the marginal sea in the western Pacific Ocean.展开更多
Ecosystem response to climate change in high-altitude regions is a focus on global change research. Picea/Abies forests are widely distributed at high altitudes of East and Central Asia, and their distribution changes...Ecosystem response to climate change in high-altitude regions is a focus on global change research. Picea/Abies forests are widely distributed at high altitudes of East and Central Asia, and their distribution changes are sensitive to climate change. Humidity is an important climatic factor that affects high-altitude ecosystems; however, the relationship between distribution changes of Picea/Abies forests and millennial-scale variability of humidity is still not dear. Palynological records can provide insights into millennial-scale paleovegetation changes, which have been successfully used to reconstruct past climate change in East and Central Asia. In this study, we synthesized 24 Picea/Abies pollen and humidity/moisture changes based upon Holocene lake records in East and Central Asia in order to explore the response of high-latitude ecosystem to millennial-scale climate change. The changing pattern of Holocene lacustrine Picea/Abies pollen in arid Central Asia differs from that of monsoonal East Asia, which can be due to different millennial-scale climate change patterns between monsoonal and arid Central Asia. Then, the relationship between changes in Picea/Abies pollen and humidity/moisture conditions was examined based on a comparison of pollen and humidity/moisture records. The results indicate that millennial-scale Picea/Abies distribution changes aremainly controlled by moisture variability at high altitudes, while the temperature effect plays a minor role in Picea/Abies distribution changes. Moreover, this research proves that lacustrine Picea/Abies pollen can be used as an indicator of millennial-scale humidity/moisture evolution at high altitudes in East and Central Asia.展开更多
Free-standing metallic nanostructures are considered to be highly relevant to many branches of science and technology with applications of three dimensional metallic nanostructures ranging from optical reflectors,actu...Free-standing metallic nanostructures are considered to be highly relevant to many branches of science and technology with applications of three dimensional metallic nanostructures ranging from optical reflectors,actuators,and antenna,to free-standing electrodes,mechanical,optical,and electrical resonators and sensors.Strain-induced out-of-plane fabrication has emerged as an effective method which uses relaxation of strain-mismatched materials.In this work,we report a study of the thermal annealing-induced shape modification of free-standing nanostructures,which was achieved by introducing compositional or microstructural nonuniformity to the nanowires.In particular gradient,segmented and striped hetero-nanowires were grown by focused-ion-beam-induced chemical vapor deposition,followed by rapid thermal annealing in a N2 atmosphere.Various free-standing nanostructures were produced as a result of the crystalline/grain growth and stress relief.展开更多
We report room-temperature electroluminescence (EL) from as-deposited amorphous-Si/silicon oxynitride multilayer structure prepared by plasma enhanced chemical vapor deposition. We prepared 8-period a-Si/SiOxNy multil...We report room-temperature electroluminescence (EL) from as-deposited amorphous-Si/silicon oxynitride multilayer structure prepared by plasma enhanced chemical vapor deposition. We prepared 8-period a-Si/SiOxNy multilayer with thickness of 4 nm both for the Si and SiOxNy sublayers. The EL spectral profile exhibits some obviously modulated features upon the barrier material. By adjusting the nitride/oxygen ratio in the barrier layer, the EL peak position can be tuned from 750 nm to 695 nm. From the result of the Raman and Fourier transform infrared results, the EL is attributed to the radiative recombination of electrons and holes in luminescent centers related to the interface. The different interface characteristics induce the shift of EL peak position.展开更多
基金This project was financially supported by Open Laboratory of Marginal Sea Geology and Paleoenvironment, South China Sea Institute of Oceanology, Chinese Academy of sciences, (No. 6).
文摘On the basis of the sound velocity measurements of the coral reef core from Nanyong No. 1 Well of Yongshu Reef in the Nansha Islands, the paper studies the relations between the vertical sound velocity transition features in the coral reef core and the corresponding stratigraphic depositional facies change as well as stratigraphic gap of erosion, analyses the cause of the sound velocity transition, expounds the concrete process of the sea level change resulting in the stratigraphic gap of erosion and facies change in the coral reef and explains the relations between the vertical sound velocity transition in the coral reef core and the corresponding stratigraphic paleoclimate and the sea level change. This study is of important practical value and theoretical significance to the island and reef engineering construction and the acoustic logging for oil exploration in the reef limestone area as well as the paleoceanographic study of the marginal sea in the western Pacific Ocean.
基金supported by the National Natural Science Foundation of China (Grant No. 41371009)the Fundamental Research Fund for the Central Universities of China (Grant No. lzujbky2013-127)
文摘Ecosystem response to climate change in high-altitude regions is a focus on global change research. Picea/Abies forests are widely distributed at high altitudes of East and Central Asia, and their distribution changes are sensitive to climate change. Humidity is an important climatic factor that affects high-altitude ecosystems; however, the relationship between distribution changes of Picea/Abies forests and millennial-scale variability of humidity is still not dear. Palynological records can provide insights into millennial-scale paleovegetation changes, which have been successfully used to reconstruct past climate change in East and Central Asia. In this study, we synthesized 24 Picea/Abies pollen and humidity/moisture changes based upon Holocene lake records in East and Central Asia in order to explore the response of high-latitude ecosystem to millennial-scale climate change. The changing pattern of Holocene lacustrine Picea/Abies pollen in arid Central Asia differs from that of monsoonal East Asia, which can be due to different millennial-scale climate change patterns between monsoonal and arid Central Asia. Then, the relationship between changes in Picea/Abies pollen and humidity/moisture conditions was examined based on a comparison of pollen and humidity/moisture records. The results indicate that millennial-scale Picea/Abies distribution changes aremainly controlled by moisture variability at high altitudes, while the temperature effect plays a minor role in Picea/Abies distribution changes. Moreover, this research proves that lacustrine Picea/Abies pollen can be used as an indicator of millennial-scale humidity/moisture evolution at high altitudes in East and Central Asia.
基金supported by the Outstanding Technical Talent Program of the Chinese Academy of Sciencesthe National Natural Science Foundation of China(Grant Nos.91123004,11104334,50825206,10834012 and 60801043)
文摘Free-standing metallic nanostructures are considered to be highly relevant to many branches of science and technology with applications of three dimensional metallic nanostructures ranging from optical reflectors,actuators,and antenna,to free-standing electrodes,mechanical,optical,and electrical resonators and sensors.Strain-induced out-of-plane fabrication has emerged as an effective method which uses relaxation of strain-mismatched materials.In this work,we report a study of the thermal annealing-induced shape modification of free-standing nanostructures,which was achieved by introducing compositional or microstructural nonuniformity to the nanowires.In particular gradient,segmented and striped hetero-nanowires were grown by focused-ion-beam-induced chemical vapor deposition,followed by rapid thermal annealing in a N2 atmosphere.Various free-standing nanostructures were produced as a result of the crystalline/grain growth and stress relief.
基金supported by the National Natural Science Foundation of China (Grant No. 60806046)the Foundation for Distinguished Young Talents in Higher Education of Guangdong (Grant Nos. LYM09101,LYM11090 and LYM10099)
文摘We report room-temperature electroluminescence (EL) from as-deposited amorphous-Si/silicon oxynitride multilayer structure prepared by plasma enhanced chemical vapor deposition. We prepared 8-period a-Si/SiOxNy multilayer with thickness of 4 nm both for the Si and SiOxNy sublayers. The EL spectral profile exhibits some obviously modulated features upon the barrier material. By adjusting the nitride/oxygen ratio in the barrier layer, the EL peak position can be tuned from 750 nm to 695 nm. From the result of the Raman and Fourier transform infrared results, the EL is attributed to the radiative recombination of electrons and holes in luminescent centers related to the interface. The different interface characteristics induce the shift of EL peak position.
