A fully differential R-MOSFET-C fourth-order Bessel active lowpass filter employing fully differential operational amplifier,passive resistors,and current-steering MOS transistors as a variable resistor is proposed.T...A fully differential R-MOSFET-C fourth-order Bessel active lowpass filter employing fully differential operational amplifier,passive resistors,and current-steering MOS transistors as a variable resistor is proposed.This proposed implementation relies on the tunability of current-steering MOS transistors operating in the triode region counteracting the concert deviation of resistor in the integrated circuit manufacturing technology in orde r that the group delay of Bessel active filter could be designed accurately.The amplifier is not only with voltage common-mode negative feedback,but also with current common-mode negative feedback,which will benefit for the stability of its D C operating point.0.75μs group delay fourth-order Bessel lowpass filter,whic h is synthesized according to passive doubly terminated RLC prototype lowpass filter,demonstrates better than -65dB THD using 100kHz,2.5V pp signal in Taiwan UMC 2P2M(2-poly,2-metal)5.0V,0.5μm CMOS technology.展开更多
Upper-level jet streams over East Asia simulated by the LASG/IAP coupled climate system model FGOALS-s2 were assessed, and the mean state bias explained in terms of synoptic-scale transient eddy activ- ity （STEA）. T...Upper-level jet streams over East Asia simulated by the LASG/IAP coupled climate system model FGOALS-s2 were assessed, and the mean state bias explained in terms of synoptic-scale transient eddy activ- ity （STEA）. The results showed that the spatial distribution of the seasonal mean jet stream was reproduced well by the model, except that following a weaker meridional temperature gradient （MTG）, the intensity of the jet stream was weaker than in National Centers for Environment Prediction （NCEP）/Department of Energy Atmospheric Model Inter-comparison Project II reanalysis data （NCEP2）. Based on daily mean data, the jet core number was counted to identify the geographical border between the East Asian Sub- tropical Jet （EASJ） and the East Asian Polar-front Jet （EAPJ）. The border is located over the Tibetan Plateau according to NCEP2 data, but was not evident in FGOALS-s2 simulations. The seasonal cycles of the jet streams were found to be reasonably reproduced, except that they shifted northward relative to reanalysis data in boreal summer owing to the northward shift of negative MTGs. To identify the reasons for mean state bias, the dynamical and thermal forcings of STEA on mean flow were examined with a focus on boreal winter. The dynamical and thermal forcings were estimated by extended Eliassen-Palm flux （E） and transient heat flux, respectively. The results showed that the failure to reproduce the tripolar-pattern of the divergence of E over the jet regions led to an unsuccessful separation of the EASJ and EAPJ, while dynamical forcing contributed less to the weaker EASJ. In contrast, the weaker transient heat flux partly explained the weaker EASJ over the ocean.展开更多
The key research and development steps for bioactive glass (45S5 Bioglass) are documented from the date of discovery in 1969 through FDA approvals of the first dental, ENT, maxillo-facial and orthopedic clinical produ...The key research and development steps for bioactive glass (45S5 Bioglass) are documented from the date of discovery in 1969 through FDA approvals of the first dental, ENT, maxillo-facial and orthopedic clinical products. Understanding the mechanisms and quantifying the rapid surface reactions to form a bone-bonding hydroxyl-carbonate apatite (HCA) layer on the bioactive glass in contact with living bone was a vital part of the early development of this class of biomaterials. A key later discovery was enhanced osteogenesis and in situ bone regeneration by controlled release of ionic dissolution products from the bioactive glass particulates that leads to up-regulation and activation of seven families of genes, a process called osteostimulation.展开更多
目的:采用高效液相色谱法测定化合物ent-kaur-16-en-19-oic ac id在光叶番荔枝不同部位和番荔枝属不同种类植物叶子中的含量。方法:色谱条件为:Nuc leosil C18色谱柱,流动相选用乙睛:水(含1%冰醋酸)=67.5:32.5,检测波长211nm。结果:平...目的:采用高效液相色谱法测定化合物ent-kaur-16-en-19-oic ac id在光叶番荔枝不同部位和番荔枝属不同种类植物叶子中的含量。方法:色谱条件为:Nuc leosil C18色谱柱,流动相选用乙睛:水(含1%冰醋酸)=67.5:32.5,检测波长211nm。结果:平均回收率为98.41%,光叶番荔枝树皮、光叶番荔枝树枝(去皮)、光叶番荔枝树叶、AP番荔枝树叶、牛心番荔枝树叶、山刺番荔枝树叶中化合物ent-kaur-16-en-19-oic ac id的含量分别为0.7147%、0.01252%、0.01773%、0.04212%、0.007305%、0.09083%。结论:在光叶番荔枝各部位中,树皮的含量最高,达0.7147%,在所测番荔枝属植物的树叶中,山刺番荔枝树叶中含量最高,达0.09083%。展开更多
文摘A fully differential R-MOSFET-C fourth-order Bessel active lowpass filter employing fully differential operational amplifier,passive resistors,and current-steering MOS transistors as a variable resistor is proposed.This proposed implementation relies on the tunability of current-steering MOS transistors operating in the triode region counteracting the concert deviation of resistor in the integrated circuit manufacturing technology in orde r that the group delay of Bessel active filter could be designed accurately.The amplifier is not only with voltage common-mode negative feedback,but also with current common-mode negative feedback,which will benefit for the stability of its D C operating point.0.75μs group delay fourth-order Bessel lowpass filter,whic h is synthesized according to passive doubly terminated RLC prototype lowpass filter,demonstrates better than -65dB THD using 100kHz,2.5V pp signal in Taiwan UMC 2P2M(2-poly,2-metal)5.0V,0.5μm CMOS technology.
基金supported by the National High Technology Research and Development Program of China(Grant No.2010AA012304)the National Program on Key Basic Research Project of China(Grant No.2010CB951904)+1 种基金the National Natural Science Foundation of China project(Grant No.41125017)the"Strategic Priority Research Program-Climate Change:Carbon Budget and RelatedIssues"of the Chinese Academy of Sciences(Grant No.XDA05110301)
文摘Upper-level jet streams over East Asia simulated by the LASG/IAP coupled climate system model FGOALS-s2 were assessed, and the mean state bias explained in terms of synoptic-scale transient eddy activ- ity （STEA）. The results showed that the spatial distribution of the seasonal mean jet stream was reproduced well by the model, except that following a weaker meridional temperature gradient （MTG）, the intensity of the jet stream was weaker than in National Centers for Environment Prediction （NCEP）/Department of Energy Atmospheric Model Inter-comparison Project II reanalysis data （NCEP2）. Based on daily mean data, the jet core number was counted to identify the geographical border between the East Asian Sub- tropical Jet （EASJ） and the East Asian Polar-front Jet （EAPJ）. The border is located over the Tibetan Plateau according to NCEP2 data, but was not evident in FGOALS-s2 simulations. The seasonal cycles of the jet streams were found to be reasonably reproduced, except that they shifted northward relative to reanalysis data in boreal summer owing to the northward shift of negative MTGs. To identify the reasons for mean state bias, the dynamical and thermal forcings of STEA on mean flow were examined with a focus on boreal winter. The dynamical and thermal forcings were estimated by extended Eliassen-Palm flux （E） and transient heat flux, respectively. The results showed that the failure to reproduce the tripolar-pattern of the divergence of E over the jet regions led to an unsuccessful separation of the EASJ and EAPJ, while dynamical forcing contributed less to the weaker EASJ. In contrast, the weaker transient heat flux partly explained the weaker EASJ over the ocean.
文摘The key research and development steps for bioactive glass (45S5 Bioglass) are documented from the date of discovery in 1969 through FDA approvals of the first dental, ENT, maxillo-facial and orthopedic clinical products. Understanding the mechanisms and quantifying the rapid surface reactions to form a bone-bonding hydroxyl-carbonate apatite (HCA) layer on the bioactive glass in contact with living bone was a vital part of the early development of this class of biomaterials. A key later discovery was enhanced osteogenesis and in situ bone regeneration by controlled release of ionic dissolution products from the bioactive glass particulates that leads to up-regulation and activation of seven families of genes, a process called osteostimulation.
文摘目的:采用高效液相色谱法测定化合物ent-kaur-16-en-19-oic ac id在光叶番荔枝不同部位和番荔枝属不同种类植物叶子中的含量。方法:色谱条件为:Nuc leosil C18色谱柱,流动相选用乙睛:水(含1%冰醋酸)=67.5:32.5,检测波长211nm。结果:平均回收率为98.41%,光叶番荔枝树皮、光叶番荔枝树枝(去皮)、光叶番荔枝树叶、AP番荔枝树叶、牛心番荔枝树叶、山刺番荔枝树叶中化合物ent-kaur-16-en-19-oic ac id的含量分别为0.7147%、0.01252%、0.01773%、0.04212%、0.007305%、0.09083%。结论:在光叶番荔枝各部位中,树皮的含量最高,达0.7147%,在所测番荔枝属植物的树叶中,山刺番荔枝树叶中含量最高,达0.09083%。
