The NSLS-II （National Synchrotron Light Source II） is a state-of-the-art 3 GeV third generation light source currently under integrated testing and commissioning at Brook_haven National Laboratory. The vacuum system...The NSLS-II （National Synchrotron Light Source II） is a state-of-the-art 3 GeV third generation light source currently under integrated testing and commissioning at Brook_haven National Laboratory. The vacuum systems are monitored by vacuum gauges and ion pump current. The gate valves are controlled by PLC （programmable logic controllers） using voting scheme. EPICS （Experimental Physics and Industrial Control System） application codes provide the high level monitoring and control through the input-output controllers. This paper will discuss the commissioning status of the various aspects of vacuum control system.展开更多
Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energydensity lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cat...Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energydensity lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cathodes is accompanied by substantial safety and cycle-life obstacles. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions towards surface reconstructions of cathode materials is not well understood. In this work, we controlled the Li_(2)CO_(3) impurity content on LiNi_(0.83)Mn_(0.1)Co_(0.07)O_(2) cathodes using air, tank-air, and O_(2) synthesis environments. Home-built high-precision leakage current and on-line electrochemical mass spectroscopy experiments verify that Li_(2)CO_(3) impurity is a significant promoter of parasitic reactions on Ni-rich cathodes. The rate of parasitic reactions is strongly correlated to Li_(2)CO_(3) content and severe performance deterioration of Ni83 cathodes.The post-mortem characterizations via high-resolution transition electron microscope and X-ray photoelectron spectroscopy depth profiles reveal that parasitic reactions promote more Ni reduction and O deficiency and even rock-salt phase transformation at the surface of cathode materials. Our observation suggests that surface reconstructions have a strong affiliation to parasitic reactions that create chemically acidic environment to etch away the lattice oxygen and offer the electrical charge to reduce the valence state of transition metal. Thus, this study advances our understanding on surface reconstructions of Nirich cathodes and prepares us for searching for rational strategies.展开更多
Liberty State Park in New Jersey,USA,is a ＂brownfield＂ site containing various levels of contaminants.To investigate metal uptake and distributions in plants on the brownfield site,Phragmites australis and Typha lat...Liberty State Park in New Jersey,USA,is a ＂brownfield＂ site containing various levels of contaminants.To investigate metal uptake and distributions in plants on the brownfield site,Phragmites australis and Typha latifolia were collected in Liberty State Park during the growing season（May–September）in 2011 at two sites with the high and low metal loads,respectively.The objective of this study was to understand the metal（Fe,Mn,Cu,Pb and Zn）concentration and spatial distributions in P.australis and T.latifolia root systems with micro-meter scale resolution using synchrotron X-ray microfluorescence（μXRF）and synchrotron X-ray computed microtomography（μCMT）techniques.The root structure measurement by synchrotron μCMT showed that high X-ray attenuation substance appeared in the epidermis.Synchrotron μXRF measurement showed that metal concentrations and distributions in the root cross-section between epidermis and vascular tissue were statistically different.Significant correlations were found between metals（Cu,Mn,Pb and Zn）and Fe in the epidermis,implying that metals were scavenged by Fe oxides.The results from this study suggest that the expression of metal transport and accumulation within the root systems may be element specific.The information derived from this study can improve our current knowledge of the wetland plant ecological function in brownfield remediation.展开更多
In this paper, we present some preliminary studies on using a Robinson wiggler to reduce the horizontal beam emittance in the Hefei Light Source II （HLS-II） storage ring. A proof-of-principle lattice demonstrates th...In this paper, we present some preliminary studies on using a Robinson wiggler to reduce the horizontal beam emittance in the Hefei Light Source II （HLS-II） storage ring. A proof-of-principle lattice demonstrates that it is possible to reduce its emittance by 50% with a 2-meter long wiggler. This encouraging result suggests a feasible option to significantly improve the machine performance at a relatively low cost.展开更多
The structure [MnmTPP][Me2DCNQI] （TPP = tetraphenylporphinato; Me2DCNQI = 2,5-dimethyl-N,N＇-dicyanoquinonediimine） has been determined from X-ray powder diffraction data. The nonsolvated structure is composed of li...The structure [MnmTPP][Me2DCNQI] （TPP = tetraphenylporphinato; Me2DCNQI = 2,5-dimethyl-N,N＇-dicyanoquinonediimine） has been determined from X-ray powder diffraction data. The nonsolvated structure is composed of linear （I-D） chains of alternating [MnmTPP]＋ and ta-[MezDCNQI]＇- with intrachain Mn...Mn separations of 12.83 A, and a Mn-NDcNQI distance of 2.18A. The dihedral angle between the mean Mn（N4）xpp and [MezDCNQI]＇-planes, and the Mn-（N-C）ocNQ1 angle are 84.18° and 143.6°, respectively. [MnInTpP][MezDCNQI] has a Tc of 4.3 K from the 10 Hz x（T） data, 2-K coercivity of 5,600 Oe, and 6,300 emuOe/mol remnant magnetization that are reduced from that observed for related materials, and their in- clusion extends the magnetostructural correlation between the intrachain coupling and both the dihedral angle between the mean Mn（N4）xPp and [TCNE]＇-（TCNE --- tetracyanoethylene） planes and Mn-（N-C）Tcr angles. This is in accord with the in- trachain coupling arising from the overlap of the Mnm dz2-1ike singly occupied molecular orbital （SOMO） and the z component of the [TCNE]- π＊ （π2＊） SOMO, which increases with decreasing dihedral angle between the mean Mn（N4）xep and [TCNE]＇- planes and Mn-（N-C）TcNE angle.展开更多
文摘The NSLS-II （National Synchrotron Light Source II） is a state-of-the-art 3 GeV third generation light source currently under integrated testing and commissioning at Brook_haven National Laboratory. The vacuum systems are monitored by vacuum gauges and ion pump current. The gate valves are controlled by PLC （programmable logic controllers） using voting scheme. EPICS （Experimental Physics and Industrial Control System） application codes provide the high level monitoring and control through the input-output controllers. This paper will discuss the commissioning status of the various aspects of vacuum control system.
基金supported by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Officesupported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office, under Contract No. DE-SC0012704+1 种基金supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357supported by the Vehicle Technologies Office of the U.S. Department of Energy。
文摘Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energydensity lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cathodes is accompanied by substantial safety and cycle-life obstacles. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions towards surface reconstructions of cathode materials is not well understood. In this work, we controlled the Li_(2)CO_(3) impurity content on LiNi_(0.83)Mn_(0.1)Co_(0.07)O_(2) cathodes using air, tank-air, and O_(2) synthesis environments. Home-built high-precision leakage current and on-line electrochemical mass spectroscopy experiments verify that Li_(2)CO_(3) impurity is a significant promoter of parasitic reactions on Ni-rich cathodes. The rate of parasitic reactions is strongly correlated to Li_(2)CO_(3) content and severe performance deterioration of Ni83 cathodes.The post-mortem characterizations via high-resolution transition electron microscope and X-ray photoelectron spectroscopy depth profiles reveal that parasitic reactions promote more Ni reduction and O deficiency and even rock-salt phase transformation at the surface of cathode materials. Our observation suggests that surface reconstructions have a strong affiliation to parasitic reactions that create chemically acidic environment to etch away the lattice oxygen and offer the electrical charge to reduce the valence state of transition metal. Thus, this study advances our understanding on surface reconstructions of Nirich cathodes and prepares us for searching for rational strategies.
基金supported in part by the Margaret and Herman Sokol Foundation(HF)China Scholarship Council(YQ)+6 种基金the State Key Laboratory of Estuarine and Coastal Research Open Research Fund(Ref #:SKLEC-KF201304)(HF,WZ,LY,YQ)supported in part by the U.S.Department of Energy,Office of Science,Office of Workforce Development for Teachers and Scientists(WDTS)under the Visiting Faculty Program(VFP)(HF)Portions of this work were performed at Beamline X27A,National Synchrotron Light Source(NSLS),and Biosciences Department,Brookhaven National LaboratoryWork in Bioscience Department,BNL,was partially supported by the Division of Chemical Sciences,Geosciences,and Biosciences,Office of Basic Energy Sciences of the US Department of Energy through Grant DEAC0298CH10886the National Science Foundation through grant MCB-1051675(CJL)X27A is supported in part by the U.S.Department of Energy--Geosciences(DE-FG02-92ER14244 to The University of Chicago-CARS)Use of the NSLS was supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,under Contract No.DE-AC02-98CH10886
文摘Liberty State Park in New Jersey,USA,is a ＂brownfield＂ site containing various levels of contaminants.To investigate metal uptake and distributions in plants on the brownfield site,Phragmites australis and Typha latifolia were collected in Liberty State Park during the growing season（May–September）in 2011 at two sites with the high and low metal loads,respectively.The objective of this study was to understand the metal（Fe,Mn,Cu,Pb and Zn）concentration and spatial distributions in P.australis and T.latifolia root systems with micro-meter scale resolution using synchrotron X-ray microfluorescence（μXRF）and synchrotron X-ray computed microtomography（μCMT）techniques.The root structure measurement by synchrotron μCMT showed that high X-ray attenuation substance appeared in the epidermis.Synchrotron μXRF measurement showed that metal concentrations and distributions in the root cross-section between epidermis and vascular tissue were statistically different.Significant correlations were found between metals（Cu,Mn,Pb and Zn）and Fe in the epidermis,implying that metals were scavenged by Fe oxides.The results from this study suggest that the expression of metal transport and accumulation within the root systems may be element specific.The information derived from this study can improve our current knowledge of the wetland plant ecological function in brownfield remediation.
基金Introdution of Outstanding Technological Talents Program of Chinese Academy of Sciences,2010Fundamental Research Funds for the Central Universities (WK2310000032)
文摘In this paper, we present some preliminary studies on using a Robinson wiggler to reduce the horizontal beam emittance in the Hefei Light Source II （HLS-II） storage ring. A proof-of-principle lattice demonstrates that it is possible to reduce its emittance by 50% with a 2-meter long wiggler. This encouraging result suggests a feasible option to significantly improve the machine performance at a relatively low cost.
基金The structure reported in this paper has been deposited with the Cambridge Crystallographic Data Center as Supplementary Publication CCDC No.870451
文摘The structure [MnmTPP][Me2DCNQI] （TPP = tetraphenylporphinato; Me2DCNQI = 2,5-dimethyl-N,N＇-dicyanoquinonediimine） has been determined from X-ray powder diffraction data. The nonsolvated structure is composed of linear （I-D） chains of alternating [MnmTPP]＋ and ta-[MezDCNQI]＇- with intrachain Mn...Mn separations of 12.83 A, and a Mn-NDcNQI distance of 2.18A. The dihedral angle between the mean Mn（N4）xpp and [MezDCNQI]＇-planes, and the Mn-（N-C）ocNQ1 angle are 84.18° and 143.6°, respectively. [MnInTpP][MezDCNQI] has a Tc of 4.3 K from the 10 Hz x（T） data, 2-K coercivity of 5,600 Oe, and 6,300 emuOe/mol remnant magnetization that are reduced from that observed for related materials, and their in- clusion extends the magnetostructural correlation between the intrachain coupling and both the dihedral angle between the mean Mn（N4）xPp and [TCNE]＇-（TCNE --- tetracyanoethylene） planes and Mn-（N-C）Tcr angles. This is in accord with the in- trachain coupling arising from the overlap of the Mnm dz2-1ike singly occupied molecular orbital （SOMO） and the z component of the [TCNE]- π＊ （π2＊） SOMO, which increases with decreasing dihedral angle between the mean Mn（N4）xep and [TCNE]＇- planes and Mn-（N-C）TcNE angle.
