Doping is essential in the growth of bulk GaN substrates,which could help control the electrical properties to meet the requirements of various types of GaN-based devices.The progresses in the growth of undoped,Si-dop...Doping is essential in the growth of bulk GaN substrates,which could help control the electrical properties to meet the requirements of various types of GaN-based devices.The progresses in the growth of undoped,Si-doped,Ge-doped,Fedoped,and highly pure GaN by hydride vapor phase epitaxy(HVPE) are reviewed in this article.The growth technology and precursors of each type of doping are introduced.Besides,the influence of doping on the optical and electrical properties of GaN are presented in detail.Furthermore,the problems caused by doping,as well as the methods to solve them are also discussed.At last,highly pure GaN is briefly introduced,which points out a new way to realize high-purity semi-insulating(HPSI) GaN.展开更多
Magnolia sinica is one of the most endangered Magnoliaceae species in China.Seed biology information concerning its long-term ex situ conservation and utilization is insufficient.This study investigated dormancy statu...Magnolia sinica is one of the most endangered Magnoliaceae species in China.Seed biology information concerning its long-term ex situ conservation and utilization is insufficient.This study investigated dormancy status,germination requirements and storage behavior of M.sinica.Freshly matured seeds germinated to ca.86.5%at 25/15℃but poorly at 30℃;GA3 and moist chilling promoted germination significantly at 20℃.Embryos grew at temperatures(alternating or constant)between 20℃and 25℃,but not at 5℃or 30℃.Our results indicate that M.sinica seeds possibly have non-deep simple mor-phophysiological dormancy(MPD).Seeds survived desiccation to 9.27%and 4.85%moisture content(MC)as well as a further 6-month storage at-20℃and in liquid nitrogen,including recovery in vitro as excised embryos.The established protocol ensured that at least 58%of seedlings were obtained after both cold storage and cryopreservation.These results indicate that both conventional seed banking and cryopreservation have potential as long-term ex situ conservation methods,although further optimized approaches are recommended for this critically endangered magnolia species.展开更多
The membrane fusion protein CmeA and the outer membrane channel CmeC,two important components of CmeABC system in Campylobacter jejuni,were expressed in Escherichia coli.After Ni-NTA and ion exchange columns purificat...The membrane fusion protein CmeA and the outer membrane channel CmeC,two important components of CmeABC system in Campylobacter jejuni,were expressed in Escherichia coli.After Ni-NTA and ion exchange columns purification,size exclusion chromatography showed that CmeA primarily existed as trimer and CmeC existed as monomer.Then the interaction between CmeA and CmeC was analyzed by dithiobis(succinimidyl propionate)(DSP)chemical crosslinking,pull-down assay on a Ni-NTA column,and isothermal titration calorimetry(ITC)measurement.The results clearly showed the CmeA–CmeC complex band,which confirmed the interaction in vitro and this interaction is independent of substrate and CmeB.It suggests that the mechanism underlying CmeABC function in C.jejuni is similar to that of AcrABTolC in E.coli.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFB0404100 and 2016YFA0201101)the National Natural Science Foundation of China(Grant Nos.61574164,61704187,and 61604170)+2 种基金the Key Research Program of the Frontier Science of the Chinese Academy of Sciences(Grant No.QYZDB-SSW-SLH042)the State Key Program of the National Natural Science Foundation of China(Grant Nos.61734008and 11435010)the National Key Scientific Instrument and Equipment Development Project,China(Grant No.11327804)。
文摘Doping is essential in the growth of bulk GaN substrates,which could help control the electrical properties to meet the requirements of various types of GaN-based devices.The progresses in the growth of undoped,Si-doped,Ge-doped,Fedoped,and highly pure GaN by hydride vapor phase epitaxy(HVPE) are reviewed in this article.The growth technology and precursors of each type of doping are introduced.Besides,the influence of doping on the optical and electrical properties of GaN are presented in detail.Furthermore,the problems caused by doping,as well as the methods to solve them are also discussed.At last,highly pure GaN is briefly introduced,which points out a new way to realize high-purity semi-insulating(HPSI) GaN.
文摘Magnolia sinica is one of the most endangered Magnoliaceae species in China.Seed biology information concerning its long-term ex situ conservation and utilization is insufficient.This study investigated dormancy status,germination requirements and storage behavior of M.sinica.Freshly matured seeds germinated to ca.86.5%at 25/15℃but poorly at 30℃;GA3 and moist chilling promoted germination significantly at 20℃.Embryos grew at temperatures(alternating or constant)between 20℃and 25℃,but not at 5℃or 30℃.Our results indicate that M.sinica seeds possibly have non-deep simple mor-phophysiological dormancy(MPD).Seeds survived desiccation to 9.27%and 4.85%moisture content(MC)as well as a further 6-month storage at-20℃and in liquid nitrogen,including recovery in vitro as excised embryos.The established protocol ensured that at least 58%of seedlings were obtained after both cold storage and cryopreservation.These results indicate that both conventional seed banking and cryopreservation have potential as long-term ex situ conservation methods,although further optimized approaches are recommended for this critically endangered magnolia species.
基金Project supported by the National Natural Science Foundation of China(No.81371995)the Key Platform Project of the Health Department of Zhejiang Province(No.2015ZDA014)the 2015 Qianjiang Talent Program of Zhejiang Province,China
基金supported by the National Basic Research Program of China(2009CB918602)the National Natural Science Foundation of China(30970575 and 31011120381)+1 种基金Shanghai Leading Academic Discipline Project(B111)Qi Qiwas supported by the National Talent Training Fund in Basic Research of China(J1210012)
文摘The membrane fusion protein CmeA and the outer membrane channel CmeC,two important components of CmeABC system in Campylobacter jejuni,were expressed in Escherichia coli.After Ni-NTA and ion exchange columns purification,size exclusion chromatography showed that CmeA primarily existed as trimer and CmeC existed as monomer.Then the interaction between CmeA and CmeC was analyzed by dithiobis(succinimidyl propionate)(DSP)chemical crosslinking,pull-down assay on a Ni-NTA column,and isothermal titration calorimetry(ITC)measurement.The results clearly showed the CmeA–CmeC complex band,which confirmed the interaction in vitro and this interaction is independent of substrate and CmeB.It suggests that the mechanism underlying CmeABC function in C.jejuni is similar to that of AcrABTolC in E.coli.
