分布式无线通信系统(Distributed Wireless Communication System,DWCS)是近几年提出的一种新型无线通信体系结构,系统采用网络无线电技术,信号处理和控制模块均在PC工作站中完成。本文结合软件无线电相关技术,研究PC工作站在DWCS基站...分布式无线通信系统(Distributed Wireless Communication System,DWCS)是近几年提出的一种新型无线通信体系结构,系统采用网络无线电技术,信号处理和控制模块均在PC工作站中完成。本文结合软件无线电相关技术,研究PC工作站在DWCS基站中的应用。本文将详细分析软基站设计及实现的关键问题,并给出软基站系统的实测性能。展开更多
The microbial reduction of U（VI） by Bacillus sp. dwc-2, isolated from soil in Southwest China, was explored using transmission electron microscopy （TEIVI）, X-ray photoelectron spectros- copy （XPS） and X-ray abso...The microbial reduction of U（VI） by Bacillus sp. dwc-2, isolated from soil in Southwest China, was explored using transmission electron microscopy （TEIVI）, X-ray photoelectron spectros- copy （XPS） and X-ray absorption near edge spectroscopy （XANES）. Our studies indicated that approximately 16.0% of U（VI） at an initial concentration of 100 mg/L uranium nitrate could be reduced by Bacillus sp. dwc-2 at pH 8.2 under anaerobic conditions at room temperature. Additionally, natural organic matter （NOM） played an important role in enhancing the bioreduction of U（VI） by Bacillus sp. dwc-2. XPS results demonstrated that the uranium presented mixed valence states （U（VI） and U（IV）） after bioreduction, which was subse- quently confirmed by XANES. Furthermore, the TEM and high resolution transmission electron microscopy （HRTEM） analysis suggested that the reduced uranium was bioaccumulated mainly within the cell and as a crystalline structure on the cell wa11. These observations implied that the reduction of uranium may have a significant effect on its fate in the soil environment in which these bacterial strains occur.展开更多
The biosorption mechanisms of uranium on an aerobic bacterial strain Streptomyces sporoverrucosus dwc-3,isolated from a potential disposal site for（ultra-）low uraniferous radioactive waste in Southwest China,were ev...The biosorption mechanisms of uranium on an aerobic bacterial strain Streptomyces sporoverrucosus dwc-3,isolated from a potential disposal site for（ultra-）low uraniferous radioactive waste in Southwest China,were evaluated by using transmission electron microscopy（TEM）,energy dispersive X-ray（EDX）analysis,Fourier transform infrared spectroscopy（FT-IR）,X-ray photoelectron spectroscopy（XPS）,proton induced X-ray emission（PIXE）and enhanced proton backscattering spectrometry（EPBS）.Approximately60% of total uranium at an initial concentration of 10 mg/L uranium nitrate solution could be absorbed on 100 mg S.sporoverrucosus dwc-3 with an adsorption capacity of more than3.0 mg/g（wet weight）after 12 hr at room temperature at p H 3.0.The dynamic biosorption process of S.sporoverrucosus dwc-3 for uranyl ions was well described by a pseudo second-order model.S.sporoverrucosus dwc-3 could accumulate uranium on cell walls and within the cell,as revealed by SEM and TEM analysis as well as EDX spectra.XPS and FT-IR analysis further suggested that the absorbed uranium was bound to amino,phosphate and carboxyl groups of the cells.Additionally,PIXE and EPBS results confirmed that ion exchange also contributed to the adsorption process of uranium.展开更多
文摘分布式无线通信系统(Distributed Wireless Communication System,DWCS)是近几年提出的一种新型无线通信体系结构,系统采用网络无线电技术,信号处理和控制模块均在PC工作站中完成。本文结合软件无线电相关技术,研究PC工作站在DWCS基站中的应用。本文将详细分析软基站设计及实现的关键问题,并给出软基站系统的实测性能。
基金supported by the National Natural Science Foundation(Nos.21071102,91126013)Joint Funds of National Natural Science Foundation and China Academy of Engineering Physics(NSAF,No.U1330125)+1 种基金the National High Technology Research and Development Program(863)of China(No.2012AA063503)the National Fund of China for Fostering Talents in Basic Science(No.J1210004)
文摘The microbial reduction of U（VI） by Bacillus sp. dwc-2, isolated from soil in Southwest China, was explored using transmission electron microscopy （TEIVI）, X-ray photoelectron spectros- copy （XPS） and X-ray absorption near edge spectroscopy （XANES）. Our studies indicated that approximately 16.0% of U（VI） at an initial concentration of 100 mg/L uranium nitrate could be reduced by Bacillus sp. dwc-2 at pH 8.2 under anaerobic conditions at room temperature. Additionally, natural organic matter （NOM） played an important role in enhancing the bioreduction of U（VI） by Bacillus sp. dwc-2. XPS results demonstrated that the uranium presented mixed valence states （U（VI） and U（IV）） after bioreduction, which was subse- quently confirmed by XANES. Furthermore, the TEM and high resolution transmission electron microscopy （HRTEM） analysis suggested that the reduced uranium was bioaccumulated mainly within the cell and as a crystalline structure on the cell wa11. These observations implied that the reduction of uranium may have a significant effect on its fate in the soil environment in which these bacterial strains occur.
基金financially supported by the China National Natural Science Foundation(Nos.21071102,91126013)Joint Funds of China National Natural Science Foundation and China Academy of Engineering Physics(NSAF,No.U1330125)+1 种基金the State 863 project of China(No.2012AA063503)the National Fund of China for Fostering Talents in Basic Science(No.J1210004)
文摘The biosorption mechanisms of uranium on an aerobic bacterial strain Streptomyces sporoverrucosus dwc-3,isolated from a potential disposal site for（ultra-）low uraniferous radioactive waste in Southwest China,were evaluated by using transmission electron microscopy（TEM）,energy dispersive X-ray（EDX）analysis,Fourier transform infrared spectroscopy（FT-IR）,X-ray photoelectron spectroscopy（XPS）,proton induced X-ray emission（PIXE）and enhanced proton backscattering spectrometry（EPBS）.Approximately60% of total uranium at an initial concentration of 10 mg/L uranium nitrate solution could be absorbed on 100 mg S.sporoverrucosus dwc-3 with an adsorption capacity of more than3.0 mg/g（wet weight）after 12 hr at room temperature at p H 3.0.The dynamic biosorption process of S.sporoverrucosus dwc-3 for uranyl ions was well described by a pseudo second-order model.S.sporoverrucosus dwc-3 could accumulate uranium on cell walls and within the cell,as revealed by SEM and TEM analysis as well as EDX spectra.XPS and FT-IR analysis further suggested that the absorbed uranium was bound to amino,phosphate and carboxyl groups of the cells.Additionally,PIXE and EPBS results confirmed that ion exchange also contributed to the adsorption process of uranium.
