The implications of climate change during the second half of the 20th century have been reported throughout the world. Although marginal seas are sensitive to climate change and anthropogenic impacts, relatively littl...The implications of climate change during the second half of the 20th century have been reported throughout the world. Although marginal seas are sensitive to climate change and anthropogenic impacts, relatively little attention has been given to the South East Asian marginal seas. Thus, to bridge this gap in knowledge, a sediment core was collected from the coastal areas of the Leizhou Peninsula in the South China Sea （SCS） to study the inter-decadal climate change and its consequences using diatom species composition as a proxy record. Diatom absolute abundance varied from 2 300 to 68 000 and averaged 16 000 valves per gram of dry weight （v/gdw）. The fractional dissolution index （F~） was usually below 0.5, which indicates low to moderate preservation of diatom valves at coastal area of the SCS. At the inter-decadal time scale, total diatom abundance was high for the period after 1972, which coincided with 1） increased percentage of planktonic diatom abundance and F~; 2） emergence and dominance of high productivity indicative cosmopolitan species such as Thalassionema nitzschioides and Paralia sulcata （their relative abundance increased from 〈1.5% to 〉7% for the period before and after 1972, respectively）; 3） decreased relative abundance of the small-sized eutrophication indicative species, Cyclotella striata, from 70% to 40%. This study reveals that variations in the abundance of diatoms preserved in the sediment was a function of both production and dissolution/preservation of diatom valves, which in turn was intimately connected to the prevailing environmental/climatic conditions. In conclusion, these data reveal the existence of substantial changes in the coastal SCS in response to the 1970s climate shift that was recorded in different parts of the world.展开更多
Hydrous minerals are important water carriers in the crust and the mantle, especially in the subduction zone. With the recent development of the experimental technique, studies of the electrical conductivity of hydrou...Hydrous minerals are important water carriers in the crust and the mantle, especially in the subduction zone. With the recent development of the experimental technique, studies of the electrical conductivity of hydrous silicate minerals under controlled temperature, pressure and oxygen fugacity, have helped to constrain the water distribution in the Earth's interior. This paper introduces high pressure and temperature experimental study of electrical conductivity measurement of hydrous minerals such as serpentine, talc, brucite, phase A, super hydrous phase B and phase D, and assesses the data quality of the above minerals. The dehydration effect and the pressure effect on the bulk conductivity of the hydrous minerals are specifically emphasized. The conduction mechanism of hydrous minerals and the electrical structure of the subduction zone are discussed based on the available conductivity data. Finally, the potential research fields of the electrical conductivity of hydrous minerals is presented.展开更多
A high resolution record of sea-ice concentration on the North Icelandic shelf during the last millennium has been reconstructed using a diatom-based sea-ice transfer function. The reconstructed sea-ice record for the...A high resolution record of sea-ice concentration on the North Icelandic shelf during the last millennium has been reconstructed using a diatom-based sea-ice transfer function. The reconstructed sea-ice record for the top of sediment core MD99–2275 exhibits a slightly increasing trend over the last 1000 years. Prior to AD 1300 sea-ice abundance was generally below the mean value, suggesting the strong influence of warm waters from the Irminger Current during the Medieval Warm Period. A marked increase of sea-ice concentration indicates an abrupt change to colder conditions after AD 1300, corresponding to the onset of the Little Ice Age. The agreement between the reconstructed sea-ice concentration and IP25 data obtained from the same core, as well as with historical records of Icelandic sea ice, suggests that diatoms may provide a valuable tool for future quantitative reconstructions of past sea-ice variability. In addition, agreement between changes in the reconstructed sea-ice record and variations in the abundance of the major diatom components indicates that sea-ice conditions on the North Icelandic shelf are generally strongly influenced by changes in the strength of two different water masses, the cold Polar water periodically derived from the East Greenland Current and the warm Irminger Current derived from the North Atlantic Current. Our proxy evidence also indicates that variations in solar activity have a considerable impact on ocean dynamics, which in turn affects sea-ice abundance.展开更多
Metamorphic Al0.50In0.50As/Ga0.47In0.53As high electron mobility transistors (mHEMTs) grown by Metal Organic ChemicalVapor Deposition (MOCVD) on n-type silicon substrates with introduction of a novel multi-stage buffe...Metamorphic Al0.50In0.50As/Ga0.47In0.53As high electron mobility transistors (mHEMTs) grown by Metal Organic ChemicalVapor Deposition (MOCVD) on n-type silicon substrates with introduction of a novel multi-stage buffering stack scheme havebeen fabricated for the first time. 1.0- m-gate-length depletion-mode mHEMTs with maximum transconductance up to 613mS/mm are achieved. The unity current gain cut-off frequency (fT) and the maximum oscillation frequency (fmax) are 36.9 and55.6 GHz, respectively. This device has the highest fTyet reported for 1.0- m-gate-length HEMTs grown on silicon byMOCVD. Also, this performance is comparable to that of similar GaAs-based mHEMTs. These are encouraging initial resultsleading to the manufacturing potential of integrated high-speed metamorphic devices for logic applications on silicon sub-strates by MOCVD.展开更多
In this paper, we present a terahertz (THz) band-stop filter realized by fabricating a metallic T-shaped resonator pattern on the high-resistivity silicon wafer. The filter exhibits two typical band-stop response char...In this paper, we present a terahertz (THz) band-stop filter realized by fabricating a metallic T-shaped resonator pattern on the high-resistivity silicon wafer. The filter exhibits two typical band-stop response characteristics depending on the incident direction of electric field with respect to the T-shaped resonator. When the long and the short arms of the T-shaped resonator were electrically polarized by changing the incident THz wave transmission directions, the corresponding central frequencies of the band-stop filter were found to be 0.436 THz at 42dB and 0.610 THz at 28 dB, respectively. Using three-dimensional (3D) finite-integral time-domain simulations, the band-stop filter was designed, which can operate in the wavelength between 0.2 and 0.8 THz. Experimental verification was also performed using a free space THz time-domain spectroscopy system. The band-stop response characteristics are in good agreement with the simulation results. The interesting THz band-stop filtering properties suggest a promising application in the modern THz communication systems, THz time-domain spectroscopic imaging and THz continuous wave imaging.展开更多
Aqueous organic flow batteries have attracted dramatic attention for stationary energy storage due to their resource sustainability and low cost. However, the current reported systems can normally be operated stably u...Aqueous organic flow batteries have attracted dramatic attention for stationary energy storage due to their resource sustainability and low cost. However, the current reported systems can normally be operated stably under a nitrogen or argon atmosphere due to their poor stability. Herein a stable airinsensitive biphenol derivative cathode, 3,30,5,50-tetramethylaminemethylene-4,40-biphenol(TABP), with high solubility(>1.5 mol L^(-1)) and redox potential(0.91 V vs. SHE) is designed and synthesized by a scalable one-step method. Paring with silicotungstic acid(SWO), an SWO/TABP flow battery shows a stable performance of zero capacity decay over 900 cycles under the air atmosphere. Further, an SWO/TABP flow battery manifests a high rate performance with an energy efficiency of 85% at a current density of60 m A cm^(-2) and a very high volumetric capacity of more than 47 Ah L^(-1). This work provides a new and practical option for next-generation practical large-scale energy storage.展开更多
基金Supported by the National Natural Science Foundation of China(No.41476116)the National Key Research and Development Program of China(No.2016YFA0601302)
文摘The implications of climate change during the second half of the 20th century have been reported throughout the world. Although marginal seas are sensitive to climate change and anthropogenic impacts, relatively little attention has been given to the South East Asian marginal seas. Thus, to bridge this gap in knowledge, a sediment core was collected from the coastal areas of the Leizhou Peninsula in the South China Sea （SCS） to study the inter-decadal climate change and its consequences using diatom species composition as a proxy record. Diatom absolute abundance varied from 2 300 to 68 000 and averaged 16 000 valves per gram of dry weight （v/gdw）. The fractional dissolution index （F~） was usually below 0.5, which indicates low to moderate preservation of diatom valves at coastal area of the SCS. At the inter-decadal time scale, total diatom abundance was high for the period after 1972, which coincided with 1） increased percentage of planktonic diatom abundance and F~; 2） emergence and dominance of high productivity indicative cosmopolitan species such as Thalassionema nitzschioides and Paralia sulcata （their relative abundance increased from 〈1.5% to 〉7% for the period before and after 1972, respectively）; 3） decreased relative abundance of the small-sized eutrophication indicative species, Cyclotella striata, from 70% to 40%. This study reveals that variations in the abundance of diatoms preserved in the sediment was a function of both production and dissolution/preservation of diatom valves, which in turn was intimately connected to the prevailing environmental/climatic conditions. In conclusion, these data reveal the existence of substantial changes in the coastal SCS in response to the 1970s climate shift that was recorded in different parts of the world.
基金supported by the National Natural Science Foundation of China(Grant Nos.41590623&41472040)the Fundamental Research Funds for the Central Universities+2 种基金China University of Geosciences(Grant No.CUGL150801)Special Fund from the State Key Laboratory of Geological Processes and Mineral ResourcesChina University of Geosciences(Grant No.MSFGPMR201408)
文摘Hydrous minerals are important water carriers in the crust and the mantle, especially in the subduction zone. With the recent development of the experimental technique, studies of the electrical conductivity of hydrous silicate minerals under controlled temperature, pressure and oxygen fugacity, have helped to constrain the water distribution in the Earth's interior. This paper introduces high pressure and temperature experimental study of electrical conductivity measurement of hydrous minerals such as serpentine, talc, brucite, phase A, super hydrous phase B and phase D, and assesses the data quality of the above minerals. The dehydration effect and the pressure effect on the bulk conductivity of the hydrous minerals are specifically emphasized. The conduction mechanism of hydrous minerals and the electrical structure of the subduction zone are discussed based on the available conductivity data. Finally, the potential research fields of the electrical conductivity of hydrous minerals is presented.
基金supported by the National Natural Science Foundation of China(Grant Nos.41406209,41176048)Chinese Polar Environment Comprehensive Investigation & Assessment Programme(Grant No.CHINARE2014-03-02)International Cooperation Project of Chinese Arctic and Antarctic Administration,SOA(Grant No.IC201309)
文摘A high resolution record of sea-ice concentration on the North Icelandic shelf during the last millennium has been reconstructed using a diatom-based sea-ice transfer function. The reconstructed sea-ice record for the top of sediment core MD99–2275 exhibits a slightly increasing trend over the last 1000 years. Prior to AD 1300 sea-ice abundance was generally below the mean value, suggesting the strong influence of warm waters from the Irminger Current during the Medieval Warm Period. A marked increase of sea-ice concentration indicates an abrupt change to colder conditions after AD 1300, corresponding to the onset of the Little Ice Age. The agreement between the reconstructed sea-ice concentration and IP25 data obtained from the same core, as well as with historical records of Icelandic sea ice, suggests that diatoms may provide a valuable tool for future quantitative reconstructions of past sea-ice variability. In addition, agreement between changes in the reconstructed sea-ice record and variations in the abundance of the major diatom components indicates that sea-ice conditions on the North Icelandic shelf are generally strongly influenced by changes in the strength of two different water masses, the cold Polar water periodically derived from the East Greenland Current and the warm Irminger Current derived from the North Atlantic Current. Our proxy evidence also indicates that variations in solar activity have a considerable impact on ocean dynamics, which in turn affects sea-ice abundance.
文摘Metamorphic Al0.50In0.50As/Ga0.47In0.53As high electron mobility transistors (mHEMTs) grown by Metal Organic ChemicalVapor Deposition (MOCVD) on n-type silicon substrates with introduction of a novel multi-stage buffering stack scheme havebeen fabricated for the first time. 1.0- m-gate-length depletion-mode mHEMTs with maximum transconductance up to 613mS/mm are achieved. The unity current gain cut-off frequency (fT) and the maximum oscillation frequency (fmax) are 36.9 and55.6 GHz, respectively. This device has the highest fTyet reported for 1.0- m-gate-length HEMTs grown on silicon byMOCVD. Also, this performance is comparable to that of similar GaAs-based mHEMTs. These are encouraging initial resultsleading to the manufacturing potential of integrated high-speed metamorphic devices for logic applications on silicon sub-strates by MOCVD.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61171051, 50971094, 61072136)
文摘In this paper, we present a terahertz (THz) band-stop filter realized by fabricating a metallic T-shaped resonator pattern on the high-resistivity silicon wafer. The filter exhibits two typical band-stop response characteristics depending on the incident direction of electric field with respect to the T-shaped resonator. When the long and the short arms of the T-shaped resonator were electrically polarized by changing the incident THz wave transmission directions, the corresponding central frequencies of the band-stop filter were found to be 0.436 THz at 42dB and 0.610 THz at 28 dB, respectively. Using three-dimensional (3D) finite-integral time-domain simulations, the band-stop filter was designed, which can operate in the wavelength between 0.2 and 0.8 THz. Experimental verification was also performed using a free space THz time-domain spectroscopy system. The band-stop response characteristics are in good agreement with the simulation results. The interesting THz band-stop filtering properties suggest a promising application in the modern THz communication systems, THz time-domain spectroscopic imaging and THz continuous wave imaging.
基金The authors acknowledge financial support from the National Natural Science Foundation of China(21925804,21935003)CASDOE Collaborative Project(121421KYSB20170032)+1 种基金CAS Engineering Laboratory for Electrochemical Energy Storage,Liaoning Revitalization Talents Program(XLYC1802050)China and DICP funding,China(ZZBS201707)。
文摘Aqueous organic flow batteries have attracted dramatic attention for stationary energy storage due to their resource sustainability and low cost. However, the current reported systems can normally be operated stably under a nitrogen or argon atmosphere due to their poor stability. Herein a stable airinsensitive biphenol derivative cathode, 3,30,5,50-tetramethylaminemethylene-4,40-biphenol(TABP), with high solubility(>1.5 mol L^(-1)) and redox potential(0.91 V vs. SHE) is designed and synthesized by a scalable one-step method. Paring with silicotungstic acid(SWO), an SWO/TABP flow battery shows a stable performance of zero capacity decay over 900 cycles under the air atmosphere. Further, an SWO/TABP flow battery manifests a high rate performance with an energy efficiency of 85% at a current density of60 m A cm^(-2) and a very high volumetric capacity of more than 47 Ah L^(-1). This work provides a new and practical option for next-generation practical large-scale energy storage.
