随着低轨星座建设的不断推进,计算卫星空间信号测距误差(signal in space range error,SISRE)的面向对象不再局限于全球卫星导航系统(Global Navigation Satellite System,GNSS)的地面用户,还包括GNSS的低轨星载用户和低轨导航系统地面...随着低轨星座建设的不断推进,计算卫星空间信号测距误差(signal in space range error,SISRE)的面向对象不再局限于全球卫星导航系统(Global Navigation Satellite System,GNSS)的地面用户,还包括GNSS的低轨星载用户和低轨导航系统地面用户。为更好地支持基于低轨星座SISRE的解算,根据SISRE的计算原理,分别研究了低轨星载用户和低轨卫星地面用户的SISRE误差投影系数的特征。计算结果显示,GNSS卫星对地面用户的误差投影系数并不适用于低轨星载用户及低轨导航星座地面用户。当低轨卫星轨道高度由2000 km降低至300 km时,GNSS卫星对低轨星载接收机的轨道径向误差投影系数由0.96增加到0.98,轨道切法平面误差投影系数由0.20降低至0.15;低轨卫星对地面用户的轨道径向误差投影系数从0.72降至0.37,轨道切法平面误差投影系数从0.49增加至0.66。上述结果可为未来低轨卫星相关的空间信号测距误差分析以及低轨完好性研究提供重要参考。展开更多
Dysregulated energy metabolism has recently been recognized as an emerging hallmark of cancer.Tumor cells,which are characterized by abnormal glycolysis,exhibit a lower extracellular pH(6.5–7.0)than nor-mal tissues(...Dysregulated energy metabolism has recently been recognized as an emerging hallmark of cancer.Tumor cells,which are characterized by abnormal glycolysis,exhibit a lower extracellular pH(6.5–7.0)than nor-mal tissues(7.2–7.4),providing a promising target for tumor-specific imaging and therapy.However,most pH-sensitive materials are unable to distinguish such a subtle pH difference owing to their wide and continuous pH-responsive range.In this study,we developed an efficient strategy for the fabrication of a tumor metabolic acidity-activatable calcium phosphate(CaP)fluorescent probe(termed MACaP9).Unlike traditional CaP-based biomedical nanomaterials,which only work within more acidic organelles,such as endosomes and lysosomes(pH 4.0–6.0),MACaP9 could not only specifically respond to the tumor extra-cellular pH but also rapidly convert pH variations into a distinct fluorescence signal to visually dis-tinguish tumor from normal tissues.The superior sensitivity and specificity of MACaP9 enabled high-contrast visualization of a broad range of tumors,as well as small tumor lesions.展开更多
文摘随着低轨星座建设的不断推进,计算卫星空间信号测距误差(signal in space range error,SISRE)的面向对象不再局限于全球卫星导航系统(Global Navigation Satellite System,GNSS)的地面用户,还包括GNSS的低轨星载用户和低轨导航系统地面用户。为更好地支持基于低轨星座SISRE的解算,根据SISRE的计算原理,分别研究了低轨星载用户和低轨卫星地面用户的SISRE误差投影系数的特征。计算结果显示,GNSS卫星对地面用户的误差投影系数并不适用于低轨星载用户及低轨导航星座地面用户。当低轨卫星轨道高度由2000 km降低至300 km时,GNSS卫星对低轨星载接收机的轨道径向误差投影系数由0.96增加到0.98,轨道切法平面误差投影系数由0.20降低至0.15;低轨卫星对地面用户的轨道径向误差投影系数从0.72降至0.37,轨道切法平面误差投影系数从0.49增加至0.66。上述结果可为未来低轨卫星相关的空间信号测距误差分析以及低轨完好性研究提供重要参考。
基金the National Key Research and Development Program of China(2017YFC1309100,2017YFA0205200,and 2020YFA0211100)National Natural Science Foundation of China(81671753,91959124,21804104,32071406,51922077,and 51872205)+6 种基金China Postdoctoral Science Foundation(2019M650259)the Youth Innovation Team of Shaanxi UniversitiesNatural Science Foundation of Shaanxi Province of China(2020PT-020)the Fundamental Research Funds for the Central Universities(JB211202,and JC2112)the Open Project Program of the State Key Laboratory of Cancer Biology(Fourth Military Medical University)(CBSKL2019ZDKF06)the Foundation of National Facility for Translational Medicine(Shanghai)(TMSK2020-012)Young Talents Program,and Shanghai Municipal Commission of Health and Family Planning Foundation(2017YQ050)。
文摘Dysregulated energy metabolism has recently been recognized as an emerging hallmark of cancer.Tumor cells,which are characterized by abnormal glycolysis,exhibit a lower extracellular pH(6.5–7.0)than nor-mal tissues(7.2–7.4),providing a promising target for tumor-specific imaging and therapy.However,most pH-sensitive materials are unable to distinguish such a subtle pH difference owing to their wide and continuous pH-responsive range.In this study,we developed an efficient strategy for the fabrication of a tumor metabolic acidity-activatable calcium phosphate(CaP)fluorescent probe(termed MACaP9).Unlike traditional CaP-based biomedical nanomaterials,which only work within more acidic organelles,such as endosomes and lysosomes(pH 4.0–6.0),MACaP9 could not only specifically respond to the tumor extra-cellular pH but also rapidly convert pH variations into a distinct fluorescence signal to visually dis-tinguish tumor from normal tissues.The superior sensitivity and specificity of MACaP9 enabled high-contrast visualization of a broad range of tumors,as well as small tumor lesions.
