Saldigones A-C(1,3,4),three new isoprenylated flavonoids with diverse flavanone,pterocarpan,and isoflavanone architec-tures,were characterized from the roots of Salvia digitaloides,together with a known isoprenylated ...Saldigones A-C(1,3,4),three new isoprenylated flavonoids with diverse flavanone,pterocarpan,and isoflavanone architec-tures,were characterized from the roots of Salvia digitaloides,together with a known isoprenylated flavanone(2).Notably,it’s the first report of isoprenylated flavonoids from Salvia species.The structures of these isolates were elucidated by extensive spectroscopic analysis.All of the compounds were evaluated for their activities on Cav3.1 low voltage-gated Ca^(2+)channel(LVGCC),of which 2 strongly and dose-dependently inhibited Cav3.1 peak current.展开更多
This paper discusses the breakdown mechanism and proposes a new simulation and test method of breakdown voltage （BV） for an ultra-high-voltage （UHV） high-side thin layer silicon-on-insulator （SOI） p-channel low-...This paper discusses the breakdown mechanism and proposes a new simulation and test method of breakdown voltage （BV） for an ultra-high-voltage （UHV） high-side thin layer silicon-on-insulator （SOI） p-channel low-density metal- oxide semiconductor （LDMOS）. Compared with the conventional simulation method, the new one is more accordant with the actual conditions of a device that can be used in the high voltage circuit. The BV of the SOI p-channel LDMOS can be properly represented and the effect of reduced bulk field can be revealed by employing the new simulation method. Simulation results show that the off-state （on-state） BV of the SOI p-channel LDMOS can reach 741 （620） V in the 3μm-thick buried oxide layer, 50μm-length drift region, and at -400 V back-gate voltage, enabling the device to be used in a 400 V UHV integrated circuit.展开更多
Quaternary buried ancient river channels are widespread in the shallow-level sediments of the northern shelf of the South China Sea. The sedimentary sequence mainly of fluvial deposits comprise an important component ...Quaternary buried ancient river channels are widespread in the shallow-level sediments of the northern shelf of the South China Sea. The sedimentary sequence mainly of fluvial deposits comprise an important component part of the low-stand system tract and transgressive system tract in the study region. The plannar variation and spatial association of the sedimentary features such as incised valley fillings, deltaic foreset wedges and block slides of shelf-marginal fans reflect the palaeogeographic environment during the fall of the regional sea level in the northern part of the South China Sea. Based on the high-resolution seismic reflection data and gelogical data from boreholes, the present paper makes an integrated interpretation of the Quaternary ancient river channels in the shallow sediments of the study area, studies the sedimentary features of the ancient channels such as their spatial distribution, seismic facies reflection indicators, sedimentary facies and sand -body types, and discusses their formational setting and evolutionary model, with the main purpose to render a service to the hydrocarbon resources exploration and development and marine engineering in the northern shelf of the South China Sea.展开更多
This paper presents the results of equal channel angular pressing (ECAP) and subsequent heat treatment (HT) as a method to improve the wear resistance of metallic materials in friction sliding. The effect of ECAP and ...This paper presents the results of equal channel angular pressing (ECAP) and subsequent heat treatment (HT) as a method to improve the wear resistance of metallic materials in friction sliding. The effect of ECAP and HT on the microstructure and mechanical properties of low carbon steel is investigated in this work. The mechanisms of wear resistance of steel with ultrafine and nanostructures produced by equal-channel angular pressing is analyzed. The results show that ECAP at room temperature and annealing at 350°C and 450°C can be used as a technology of reducing wear in friction sliding.展开更多
The long-term existence of dam structures significantly modified the river channel. In accordance with a drastic increase of low-head dams under consideration for removal in recent years, it is important to predict th...The long-term existence of dam structures significantly modified the river channel. In accordance with a drastic increase of low-head dams under consideration for removal in recent years, it is important to predict the effects of low-head dam removal from the modified river channel by the low-head dam construction. This study intends to investigate the long-term channel evolution process following low-head construction and removal and to find out the influential parameters (sediment diameter, river bed slope, dam height) for those channel evolution by two-dimensional numerical simulation model. Following the low-head dam construction, sediment deposition rates in upstream of the low-head dam are varied with the influential parameters. The sediment deposition rates and sandbar formation with riparian vegetation settlement on sandbars have significantly affected for channel evolution following low-head dam removal. Especially the knickpoint formation and the types of vegetation (grass type and tree type) on the sandbars are critical factors for channel evolution following low-head dam removal. Through the numerical simulation results of low-head dam construction (50 years) and low-head dam removal (50 years), it is identified that the modified river channel by low-head dam may not be easily restored to pre-dam conditions following its removal especially in river geomorphology and riparian vegetation. Consequently, this study found that the reversibility following low-head dam construction and removal depends on the sediment deposition rates in upstream of the low-head dam.展开更多
To remove the scalar ambiguity in conventional blind channel estimation algorithms, totally blind channel estimation （TBCE） is proposed by using multiple constellations. To estimate the unknown scalar, its phase is ...To remove the scalar ambiguity in conventional blind channel estimation algorithms, totally blind channel estimation （TBCE） is proposed by using multiple constellations. To estimate the unknown scalar, its phase is decomposed into a fractional phase and an integer phase. However, the maximum-likelihood （ML） algorithm for the fractional phase does not have closed-form solutions and suffers from high computational complexity. By ex- ploring the structures of widely used constellations, this paper proposes a low-complexity fractional phase estimation algorithm which requires no exhaustive search. Analytical expressions of the asymptotic mean squared error （MSE） are also derived. The theo- retical analysis and simulation results indicate that the proposed fractional phase estimation algorithm exhibits almost the same performance as the ML algorithm but with significantly reduced computational burden.展开更多
基金the Foundation of Supported by National Natural Science Foundation of China(32070392 and 32070393)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK0502-0303).
文摘Saldigones A-C(1,3,4),three new isoprenylated flavonoids with diverse flavanone,pterocarpan,and isoflavanone architec-tures,were characterized from the roots of Salvia digitaloides,together with a known isoprenylated flavanone(2).Notably,it’s the first report of isoprenylated flavonoids from Salvia species.The structures of these isolates were elucidated by extensive spectroscopic analysis.All of the compounds were evaluated for their activities on Cav3.1 low voltage-gated Ca^(2+)channel(LVGCC),of which 2 strongly and dose-dependently inhibited Cav3.1 peak current.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60906038)
文摘This paper discusses the breakdown mechanism and proposes a new simulation and test method of breakdown voltage （BV） for an ultra-high-voltage （UHV） high-side thin layer silicon-on-insulator （SOI） p-channel low-density metal- oxide semiconductor （LDMOS）. Compared with the conventional simulation method, the new one is more accordant with the actual conditions of a device that can be used in the high voltage circuit. The BV of the SOI p-channel LDMOS can be properly represented and the effect of reduced bulk field can be revealed by employing the new simulation method. Simulation results show that the off-state （on-state） BV of the SOI p-channel LDMOS can reach 741 （620） V in the 3μm-thick buried oxide layer, 50μm-length drift region, and at -400 V back-gate voltage, enabling the device to be used in a 400 V UHV integrated circuit.
基金The present paper represents the result of a scientific research subject of the UNDP-assisted Project "Marine Engineering Geological Investigation of the Pearl River Mouth Basin in the Northern Party of the South China Sea" (Project No. UNDP.CPR/85/044)
文摘Quaternary buried ancient river channels are widespread in the shallow-level sediments of the northern shelf of the South China Sea. The sedimentary sequence mainly of fluvial deposits comprise an important component part of the low-stand system tract and transgressive system tract in the study region. The plannar variation and spatial association of the sedimentary features such as incised valley fillings, deltaic foreset wedges and block slides of shelf-marginal fans reflect the palaeogeographic environment during the fall of the regional sea level in the northern part of the South China Sea. Based on the high-resolution seismic reflection data and gelogical data from boreholes, the present paper makes an integrated interpretation of the Quaternary ancient river channels in the shallow sediments of the study area, studies the sedimentary features of the ancient channels such as their spatial distribution, seismic facies reflection indicators, sedimentary facies and sand -body types, and discusses their formational setting and evolutionary model, with the main purpose to render a service to the hydrocarbon resources exploration and development and marine engineering in the northern shelf of the South China Sea.
文摘This paper presents the results of equal channel angular pressing (ECAP) and subsequent heat treatment (HT) as a method to improve the wear resistance of metallic materials in friction sliding. The effect of ECAP and HT on the microstructure and mechanical properties of low carbon steel is investigated in this work. The mechanisms of wear resistance of steel with ultrafine and nanostructures produced by equal-channel angular pressing is analyzed. The results show that ECAP at room temperature and annealing at 350°C and 450°C can be used as a technology of reducing wear in friction sliding.
文摘The long-term existence of dam structures significantly modified the river channel. In accordance with a drastic increase of low-head dams under consideration for removal in recent years, it is important to predict the effects of low-head dam removal from the modified river channel by the low-head dam construction. This study intends to investigate the long-term channel evolution process following low-head construction and removal and to find out the influential parameters (sediment diameter, river bed slope, dam height) for those channel evolution by two-dimensional numerical simulation model. Following the low-head dam construction, sediment deposition rates in upstream of the low-head dam are varied with the influential parameters. The sediment deposition rates and sandbar formation with riparian vegetation settlement on sandbars have significantly affected for channel evolution following low-head dam removal. Especially the knickpoint formation and the types of vegetation (grass type and tree type) on the sandbars are critical factors for channel evolution following low-head dam removal. Through the numerical simulation results of low-head dam construction (50 years) and low-head dam removal (50 years), it is identified that the modified river channel by low-head dam may not be easily restored to pre-dam conditions following its removal especially in river geomorphology and riparian vegetation. Consequently, this study found that the reversibility following low-head dam construction and removal depends on the sediment deposition rates in upstream of the low-head dam.
基金supported by the National Science and Technology Major Project of China(2013ZX03003006-003)
文摘To remove the scalar ambiguity in conventional blind channel estimation algorithms, totally blind channel estimation （TBCE） is proposed by using multiple constellations. To estimate the unknown scalar, its phase is decomposed into a fractional phase and an integer phase. However, the maximum-likelihood （ML） algorithm for the fractional phase does not have closed-form solutions and suffers from high computational complexity. By ex- ploring the structures of widely used constellations, this paper proposes a low-complexity fractional phase estimation algorithm which requires no exhaustive search. Analytical expressions of the asymptotic mean squared error （MSE） are also derived. The theo- retical analysis and simulation results indicate that the proposed fractional phase estimation algorithm exhibits almost the same performance as the ML algorithm but with significantly reduced computational burden.
