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Age-Constrained Dynamic Content Replacing and Delivering for UAV-Assisted Context Awareness
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作者 liudi wang Shan Zhang +1 位作者 Xishuo Li Hongbin Luo 《China Communications》 SCIE CSCD 2022年第7期277-293,共17页
In this work,we employ the cache-enabled UAV to provide context information delivery to end devices that make timely and intelligent decisions.Different from the traditional network traffic,context information varies ... In this work,we employ the cache-enabled UAV to provide context information delivery to end devices that make timely and intelligent decisions.Different from the traditional network traffic,context information varies with time and brings in the ageconstrained requirement.The cached content items should be refreshed timely based on the age status to guarantee the freshness of user-received contents,which however consumes additional transmission resources.The traditional cache methods separate the caching and the transmitting,which are not suitable for the dynamic context information.We jointly design the cache replacing and content delivery based on both the user requests and the content dynamics to maximize the offloaded traffic from the ground network.The problem is formulated based on the Markov Decision Process(MDP).A sufficient condition of cache replacing is found in closed form,whereby a dynamic cache replacing and content delivery scheme is proposed based on the Deep Q-Network(DQN).Extensive simulations have been conducted.Compared with the conventional popularity-based and the modified Least Frequently Used(i.e.,LFU-dynamic)schemes,the UAV can offload around 30%traffic from the ground network by utilizing the proposed scheme in the urban scenario,according to the simulation results. 展开更多
关键词 UAV offloading context awareness onboard caching cache replacing content freshness
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Size-transformable nanoparticles with sequentially triggered drug release and enhanced penetration for anticancer therapy
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作者 Yulin Li liudi wang +8 位作者 Guoqiang Zhong Guoying wang Yanzhao Zhu Jian Li Lan Xiao Yanhui Chu Yan Wu Kaichun Li Jie Gao 《Nano Research》 SCIE EI CSCD 2023年第8期11186-11196,共11页
There are several limitations to the application of nanoparticles in the treatment of cancer,including their low drug loading,poor colloidal stability,insufficient tumor penetration,and uncontrolled release of the dru... There are several limitations to the application of nanoparticles in the treatment of cancer,including their low drug loading,poor colloidal stability,insufficient tumor penetration,and uncontrolled release of the drug.Herein,gelatin/laponite(LP)/doxorubicin(GLD)nanoparticles are developed by crosslinking LP with gelatin for doxorubicin delivery.GLD shows high doxorubicin encapsulation efficacy(99%)and strong colloidal stability,as seen from the unchanged size over the past 21 days and reduced protein absorption by 48-fold compared with unmodified laponite/doxorubicin nanoparticles.When gelatin from 115 nm GLD reaches the tumor site,matrix metallopeptidase-2(MMP-2)from the tumor environment breaks it down to release smaller 40 nm LP nanoparticles for effective tumor cell endocytosis.As demonstrated by superior penetration in both in vitro three-dimensional(3D)tumor spheroids(138-fold increase compared to the free drug)and in vivo tumor models.The intracellular low pH and MMP-2 further cause doxorubicin release after endocytosis by tumor cells,leading to a higher inhibitory potential against cancer cells.The improved anticancer effectiveness and strong in vivo biocompatibility of GLD have been confirmed using a mouse tumor-bearing model.MMP-2/pH sequentially triggered anticancer drug delivery is made possible by the logical design of tumor-penetrating GLD,offering a useful method for anticancer therapy. 展开更多
关键词 sequentially triggered drug release size-transformable NANOPARTICLES tumor penetration anticancer therapy drug delivery
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Injectable collagen scaffold promotes swine myocardial infarction recovery by long-term local retention of transplanted human umbilical cord mesenchymal stem cells 被引量:6
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作者 Qiang wangn Xiaojun He +7 位作者 Bin wang Jun Pan Chunying Shi Jie Li liudi wang Yannan Zhao Jianwu Dai Dongjin wang 《Science China(Life Sciences)》 SCIE CAS CSCD 2021年第2期269-281,共13页
Stem cell therapy is an attractive approach for recovery from myocardial infarction(MI)but faces the challenges of rapid diffusion and poor survival after transplantation.Here we developed an injectable collagen scaff... Stem cell therapy is an attractive approach for recovery from myocardial infarction(MI)but faces the challenges of rapid diffusion and poor survival after transplantation.Here we developed an injectable collagen scaffold to promote the long-term retention of transplanted cells in chronic MI.Forty-five minipigs underwent left anterior descending artery(LAD)ligation and were equally divided into three groups 2 months later(collagen scaffold loading with human umbilical mesenchymal stem cell(hUMSC)group,hUMSC group,and placebo group(only phosphate-buffered saline(PBS)injection)).Immunofluorescence staining indicated that the retention of transplanted cells was promoted by the collagen scaffold.Echocardiography and cardiac magnetic resonance imaging(CMR)showed much higher left ventricular ejection fraction(LVEF)and lower infarct size percentage in the collagen/hUMSC group than in the hUMSC and placebo groups at 12 months after treatment.There were also higher densities of vWf-,α-sma-,and cTnT-positive cells in the infarct border zone in the collagen/cell group,as revealed by immunohistochemical analysis,suggesting better angiogenesis and more cardiomyocyte survival after MI.Thus,the injectable collagen scaffold was safe and effective on a large animal myocardial model,which is beneficial for constructing a favorable microenvironment for applying stem cells in clinical MI. 展开更多
关键词 injectable collagen scaffold mesenchymal stem cell MI
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Three-dimensional bioprinting sodium alginate/gelatin scaffold combined with neural stem cells and oligodendrocytes markedly promoting nerve regeneration after spinal cord injury 被引量:5
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作者 Shuo Liu Hui Yang +5 位作者 Dong Chen Yuanyuan Xie ChenXu Tai liudi wang Peng wang Bin wang 《Regenerative Biomaterials》 SCIE EI 2022年第1期522-532,共11页
Accumulating research has indicated that the transplantation of combined stem cells and scaffolds is an effective method for spinal cord injury(SCI).The development of three-dimensional(3D)bioprinting technology can m... Accumulating research has indicated that the transplantation of combined stem cells and scaffolds is an effective method for spinal cord injury(SCI).The development of three-dimensional(3D)bioprinting technology can make the 3D scaffolds combined with cells more accurate and effective for SCI treatment.However,unmyelinated newborn nerve fibers have no nerve signaling conduction,hampering recovery of motor function.In this study,we designed and printed a type of sodium alginate/gelatin scaffold loaded with neural stem cells and oligodendrocytes,which were involved in the formation of the myelin sheaths of neural cell axons.In order to observe the effectiveness of this 3D bioprinting scaffold,we transplanted it into the completely transected rat spinal cord,and then immunofluorescence staining,hematoxylin–eosin staining and behavioral assessment were performed.The results showed that this 3D bioprinting scaffold markedly improved the hindlimb motor function and promoted nerve regeneration.These findings suggested that this novel 3D bioprinting scaffold was a good carrier for cells transplantation,thereby enhancing spinal cord repair following injury. 展开更多
关键词 three-dimensional bioprinting neural stem cell OLIGODENDROCYTES spinal cord injury
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