As well as world class Fe and REE resources the Bayan Obo mineral deposits also hosts significant niobium resources(estimated as 2.2 Mt Nb with an average grade of 0.13 wt% Nb).Niobium in this study is primarily hoste...As well as world class Fe and REE resources the Bayan Obo mineral deposits also hosts significant niobium resources(estimated as 2.2 Mt Nb with an average grade of 0.13 wt% Nb).Niobium in this study is primarily hosted in aeschynite-(Ce) and(Nd),but with subsidiary amounts of pyrochlore,fergusonite-(Ce),fersmite and columbite.Here we report on the paragenetic and textural setting of aeschynite,pyrochlore and fergusonite in the main ore bodies and in a carbonatite dyke.Niobium in a carbonatite sample is hosted in a phase tentatively(due to significant Ca,Mn and Ti contents) identified as fergusonite-(Ce).Aeschynite occurs overgrowing foliation in banded ores,in fractures and vugs in aegirine-rich rocks and in calcite veins.The composition in all settings is similar,but some examples in banded ores develop significant zonation in Y,Th and the REE,inferred to relate to buffering of halogen acid species to low levels by dissolution and fluoritisation of calcite,and the preferential precipitation of LREE from solution due to lower mineral solubility products compared to the HREE.Although lower in total concentration the ratios of REE in pyrochlore are similar to those of aeschynite and suggest the same metal source.The crystallisation of pyrochlore probably relates to growth in paragenetic settings where carbonates had already been eliminated and hence the buffering of F-species activities in the hydrothermal fluid was reduced.Both aeschynite and pyrochlore show evidence of alteration.Primary alteration of aeschynite resulted in leaching of A-site cations(Ca,REE,Th) and Nb,addition of Fe,and ultimately replacement by Ba-Ti phases(baotite and bafertisite).Secondary,metamictisation enhanced,possibly supergene alteration of pyrochlore resulted in hydration,leaching of A-site cations leading to the development of lattice vacancies and increases in Si.The presence of hydrothermal Nb resources at Bayan Obo suggests there may be potential for further Nb discoveries in the area,whilst the trends in element mobility during alteration have significant implications for the utility of A-B oxides as components of materials for immobilisation of radionuclides.展开更多
The paper describes some of the key issues that need to be addressed in the design and execution of underground structures to ensure their long term suitability as watertight units and outlines through practical examp...The paper describes some of the key issues that need to be addressed in the design and execution of underground structures to ensure their long term suitability as watertight units and outlines through practical examples of structures that have not achieved their design requirements which situations need to be considered. Waterproofing is not an exact science but a combination of theoretical knowledge and practical experience based on the five key factors: Environment, Design, Materials, Application and Use of the Structure.In conclusion the paper outlines the advances in crack control to date that can provide the necessary long term guarantees.The adoption of re - injectable crack inducers permitted the Client to save over 10% on construction costs and reduced the construction time by six months.展开更多
目的发布欧洲重症医学学会(European Society of Intensive Care Medicine,ESICM)关于神经重症监护患者液体治疗的专家共识和临床实践推荐意见。设计在2016年10月召开的ESICM LIVE 2016会议上召集了一个由22名国际专家组成的共识委员会...目的发布欧洲重症医学学会(European Society of Intensive Care Medicine,ESICM)关于神经重症监护患者液体治疗的专家共识和临床实践推荐意见。设计在2016年10月召开的ESICM LIVE 2016会议上召集了一个由22名国际专家组成的共识委员会,随后委员会成员通过电话会议和在线讨论制定本专家共识。方法回顾人群、干预、对比和结局(population,intervention,comparison,and outcomes,PICO)问题,根据需要进行更新并得到证据概要。本共识关注3个主要议题:(1)神经重症监护患者的液体复苏和维持;(2)高渗液体在颅内压控制中的应用;(3)蛛网膜下腔出血后迟发性脑缺血的液体管理。经过广泛的文献检索,应用推荐分级的评估、制订与评价(Gradingof Recommendations Assessment,Development and Evaluation,GRADE)系统原则评估证据质量(从高到极低),制定治疗推荐(强或弱),并在适用时发布最佳实践声明。基于文献和专家意见提供的综合证据,应用改良德尔菲方法(使用序贯方法以避免偏倚和误解)产生最终共识声明。结果最终共识包含总共32条声明,其中13条为强推荐,17条为弱推荐,另外2条声明未提供推荐意见。结论我们发布了一份关于神经重症监护患者液体治疗的共识声明和临床实践推荐。展开更多
This study examines the impact of spatial landscape configuration(e.g.,clustered,dispersed)on land-surface temperatures(LST)over Phoenix,Arizona,and Las Vegas,Nevada,USA.We classified detailed land-cover types via obj...This study examines the impact of spatial landscape configuration(e.g.,clustered,dispersed)on land-surface temperatures(LST)over Phoenix,Arizona,and Las Vegas,Nevada,USA.We classified detailed land-cover types via object-based image analysis(OBIA)using Geoeye-1 at 3-m resolution(Las Vegas)and QuickBird at 2.4-m resolution(Phoenix).Spatial autocorrelation(local Moran’s I)was then used to test for spatial dependence and to determine how clustered or dispersed points were arranged.Next,we used Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER)data acquired over Phoenix(daytime on 10 June and nighttime on 17 October 2011)and Las Vegas(daytime on 6 July and nighttime on 27 August 2005)to examine day-and nighttime LST with regard to the spatial arrangement of anthropogenic and vegetation features.Local Moran’s I values of each land-cover type were spatially correlated to surface temperature.The spatial configuration of grass and trees shows strong negative correlations with LST,implying that clustered vegetation lowers surface temperatures more effectively.In contrast,clustered spatial arrangements of anthropogenic land-cover types,especially impervious surfaces and open soil,elevate LST.These findings suggest that city planners and managers should,where possible,incorporate clustered grass and trees to disperse unmanaged soil and paved surfaces,and fill open unmanaged soil with vegetation.Our findings are in line with national efforts to augment and strengthen green infrastructure,complete streets,parking management,and transit-oriented development practices,and reduce sprawling,unwalkable housing development.展开更多
文摘As well as world class Fe and REE resources the Bayan Obo mineral deposits also hosts significant niobium resources(estimated as 2.2 Mt Nb with an average grade of 0.13 wt% Nb).Niobium in this study is primarily hosted in aeschynite-(Ce) and(Nd),but with subsidiary amounts of pyrochlore,fergusonite-(Ce),fersmite and columbite.Here we report on the paragenetic and textural setting of aeschynite,pyrochlore and fergusonite in the main ore bodies and in a carbonatite dyke.Niobium in a carbonatite sample is hosted in a phase tentatively(due to significant Ca,Mn and Ti contents) identified as fergusonite-(Ce).Aeschynite occurs overgrowing foliation in banded ores,in fractures and vugs in aegirine-rich rocks and in calcite veins.The composition in all settings is similar,but some examples in banded ores develop significant zonation in Y,Th and the REE,inferred to relate to buffering of halogen acid species to low levels by dissolution and fluoritisation of calcite,and the preferential precipitation of LREE from solution due to lower mineral solubility products compared to the HREE.Although lower in total concentration the ratios of REE in pyrochlore are similar to those of aeschynite and suggest the same metal source.The crystallisation of pyrochlore probably relates to growth in paragenetic settings where carbonates had already been eliminated and hence the buffering of F-species activities in the hydrothermal fluid was reduced.Both aeschynite and pyrochlore show evidence of alteration.Primary alteration of aeschynite resulted in leaching of A-site cations(Ca,REE,Th) and Nb,addition of Fe,and ultimately replacement by Ba-Ti phases(baotite and bafertisite).Secondary,metamictisation enhanced,possibly supergene alteration of pyrochlore resulted in hydration,leaching of A-site cations leading to the development of lattice vacancies and increases in Si.The presence of hydrothermal Nb resources at Bayan Obo suggests there may be potential for further Nb discoveries in the area,whilst the trends in element mobility during alteration have significant implications for the utility of A-B oxides as components of materials for immobilisation of radionuclides.
文摘The paper describes some of the key issues that need to be addressed in the design and execution of underground structures to ensure their long term suitability as watertight units and outlines through practical examples of structures that have not achieved their design requirements which situations need to be considered. Waterproofing is not an exact science but a combination of theoretical knowledge and practical experience based on the five key factors: Environment, Design, Materials, Application and Use of the Structure.In conclusion the paper outlines the advances in crack control to date that can provide the necessary long term guarantees.The adoption of re - injectable crack inducers permitted the Client to save over 10% on construction costs and reduced the construction time by six months.
文摘目的发布欧洲重症医学学会(European Society of Intensive Care Medicine,ESICM)关于神经重症监护患者液体治疗的专家共识和临床实践推荐意见。设计在2016年10月召开的ESICM LIVE 2016会议上召集了一个由22名国际专家组成的共识委员会,随后委员会成员通过电话会议和在线讨论制定本专家共识。方法回顾人群、干预、对比和结局(population,intervention,comparison,and outcomes,PICO)问题,根据需要进行更新并得到证据概要。本共识关注3个主要议题:(1)神经重症监护患者的液体复苏和维持;(2)高渗液体在颅内压控制中的应用;(3)蛛网膜下腔出血后迟发性脑缺血的液体管理。经过广泛的文献检索,应用推荐分级的评估、制订与评价(Gradingof Recommendations Assessment,Development and Evaluation,GRADE)系统原则评估证据质量(从高到极低),制定治疗推荐(强或弱),并在适用时发布最佳实践声明。基于文献和专家意见提供的综合证据,应用改良德尔菲方法(使用序贯方法以避免偏倚和误解)产生最终共识声明。结果最终共识包含总共32条声明,其中13条为强推荐,17条为弱推荐,另外2条声明未提供推荐意见。结论我们发布了一份关于神经重症监护患者液体治疗的共识声明和临床实践推荐。
基金This research study is supported by a NASA-funded project(NASA award number NNX12AM88G)titled"Understanding Impacts of Desert Urbanization on Climate and Surrounding Environments to Foster Sustainable Cities Using Remote Sensing and Numerical Modeling."This material is also based upon work supported by the National Science Foundation under grant number BCS-1026865,Central Arizona-Phoenix Long-Term Ecological Research(CAP LTER),and under NSF award number SES-0951366 and SES-0345945,Decision Center for a Desert City(DCDC).
文摘This study examines the impact of spatial landscape configuration(e.g.,clustered,dispersed)on land-surface temperatures(LST)over Phoenix,Arizona,and Las Vegas,Nevada,USA.We classified detailed land-cover types via object-based image analysis(OBIA)using Geoeye-1 at 3-m resolution(Las Vegas)and QuickBird at 2.4-m resolution(Phoenix).Spatial autocorrelation(local Moran’s I)was then used to test for spatial dependence and to determine how clustered or dispersed points were arranged.Next,we used Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER)data acquired over Phoenix(daytime on 10 June and nighttime on 17 October 2011)and Las Vegas(daytime on 6 July and nighttime on 27 August 2005)to examine day-and nighttime LST with regard to the spatial arrangement of anthropogenic and vegetation features.Local Moran’s I values of each land-cover type were spatially correlated to surface temperature.The spatial configuration of grass and trees shows strong negative correlations with LST,implying that clustered vegetation lowers surface temperatures more effectively.In contrast,clustered spatial arrangements of anthropogenic land-cover types,especially impervious surfaces and open soil,elevate LST.These findings suggest that city planners and managers should,where possible,incorporate clustered grass and trees to disperse unmanaged soil and paved surfaces,and fill open unmanaged soil with vegetation.Our findings are in line with national efforts to augment and strengthen green infrastructure,complete streets,parking management,and transit-oriented development practices,and reduce sprawling,unwalkable housing development.
