Recent days,aggregatable nanoparticles,which can specifically respond to certain stimulus,have shown great potential in tumor-targeted drug delivery with prolonged retention and deeper penetration.In this review,we su...Recent days,aggregatable nanoparticles,which can specifically respond to certain stimulus,have shown great potential in tumor-targeted drug delivery with prolonged retention and deeper penetration.In this review,we summarize recent advances in design of aggregatable nanoparticles by different stimuli.Internal(pH and enzyme)and external(light,temperature and ROS)stimuli are introduced for a comprehensive description.Moreover,the aggregated nanoparticles usually exhibit photothermal,photoacoustic,PET and enhanced MRI contrast,which is also described.In the end,we discuss about the potential applications and challenges for the future clinical translation.展开更多
Two-dimensional(2D)metal organic frameworks(MOFs)are emerging as low-cost oxygen evolution reaction(OER)electrocatalysts,however,suffering aggregation and poor operation stability.Herein,ultrafine Fe_(3)O_(4) nanopart...Two-dimensional(2D)metal organic frameworks(MOFs)are emerging as low-cost oxygen evolution reaction(OER)electrocatalysts,however,suffering aggregation and poor operation stability.Herein,ultrafine Fe_(3)O_(4) nanoparticles(diameter:6±2 nm)are homogeneously immobilized on 2D Ni based MOFs(Ni-BDC,thickness:5±1 nm)to improve the OER stability.Electronic structure modulation for enhanced catalytic activity is studied via adjusting the amount of Fe_(3)O_(4) nanoparticles on Ni-BDC.The optimal Fe_(3)O_(4)/Ni-BDC achieves the best OER performance with an overpotential of 295 mV at 10 mA cm^(-2),a Tafel slope of 47.8 mV dec^(-1) and a considerable catalytic durability of more than 40 h(less than 5 h for Ni-BDC alone).DFT calculations confirm that the active sites for Fe_(3)O_(4)/Ni-BDC are mainly contributed by Fe species with a higher oxidation state,and the potential-determining step(PDS)is the formation of the adsorbed O*species,which are facilitated in the composite.展开更多
检测与跟踪视频中的篮球可为教练复盘比赛提供关键信息。在比赛的视频流中,由于篮球目标较小,YOLOv5(You Only Look Once v5)算法对篮球与其他类圆形小目标的区分度较低。为此,在YOLOv5算法的基础上,首先采用V-C3(VoVNet C3)模块代替原C...检测与跟踪视频中的篮球可为教练复盘比赛提供关键信息。在比赛的视频流中,由于篮球目标较小,YOLOv5(You Only Look Once v5)算法对篮球与其他类圆形小目标的区分度较低。为此,在YOLOv5算法的基础上,首先采用V-C3(VoVNet C3)模块代替原C3模块,以解决篮球特征单一的问题,并通过K-L散度(Kullback-Leibler Divergence)验证改进的有效性。其次,采用桥式路径聚合网络(Bridge Path Aggregation Network,BPANet)代替原路径聚合网络(Path Aggregation Network,PANet),以解决场景中小目标篮球的检测问题。第三,构建分类惩罚机制,以降低篮球与相似目标的误检率。第四,探讨了各参数对篮球检测算法性能的影响,并探寻最佳参数取值和模型结构。实验结果表明,改进后算法的识别精度比原始YOLOv5算法提高了3个百分点,在COCO部分数据集上平均精度提高了2.4个百分点,算法的参数规模降低了5.3个百分点。本文对YOLOv5算法提出的4种改进策略,在保持较高实时性的基础上提高了视频中篮球目标的检测精度并降低模型规模,为类似的目标检测提供了一种新思路。展开更多
基金supported by the National Natural Science Foundation of China(No.81961138009)the Young Elite Scientists Sponsorship Program by CAST(No.2017QNR001)+1 种基金the Fundamental Research Funds for the Central Universities,111 Project(No.B18035)RFBR and National Natural Science Foundation of China Collaboration Project(No.19-58-55001)。
文摘Recent days,aggregatable nanoparticles,which can specifically respond to certain stimulus,have shown great potential in tumor-targeted drug delivery with prolonged retention and deeper penetration.In this review,we summarize recent advances in design of aggregatable nanoparticles by different stimuli.Internal(pH and enzyme)and external(light,temperature and ROS)stimuli are introduced for a comprehensive description.Moreover,the aggregated nanoparticles usually exhibit photothermal,photoacoustic,PET and enhanced MRI contrast,which is also described.In the end,we discuss about the potential applications and challenges for the future clinical translation.
基金support from the Chinese Scholarship Council(201706220080)for W.H.the Natural Science Foundation of Hunan Province(2019JJ50526)for C.P.+1 种基金The Danish Council for Independent Research for the YDUN project(DFF 4093-00297)to J.Z.Villum Experiment(grant No.35844)for X.X.
文摘Two-dimensional(2D)metal organic frameworks(MOFs)are emerging as low-cost oxygen evolution reaction(OER)electrocatalysts,however,suffering aggregation and poor operation stability.Herein,ultrafine Fe_(3)O_(4) nanoparticles(diameter:6±2 nm)are homogeneously immobilized on 2D Ni based MOFs(Ni-BDC,thickness:5±1 nm)to improve the OER stability.Electronic structure modulation for enhanced catalytic activity is studied via adjusting the amount of Fe_(3)O_(4) nanoparticles on Ni-BDC.The optimal Fe_(3)O_(4)/Ni-BDC achieves the best OER performance with an overpotential of 295 mV at 10 mA cm^(-2),a Tafel slope of 47.8 mV dec^(-1) and a considerable catalytic durability of more than 40 h(less than 5 h for Ni-BDC alone).DFT calculations confirm that the active sites for Fe_(3)O_(4)/Ni-BDC are mainly contributed by Fe species with a higher oxidation state,and the potential-determining step(PDS)is the formation of the adsorbed O*species,which are facilitated in the composite.
