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A Low-Cost Dual Energy CT System with Sparse Data

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Tsinghua Science and Technology 2014年第2期19卷 184-194页

作者： Yuanyuan Liu Jianping Cheng Li Zhang Yuxiang Xing Zhiqiang Chen Peng Zheng nuclear and Radiation Safety Center Ministry of Environmental Protection of China Department of engineering Physics Tsinghua University

Dual Energy CT （DECT） has recently gained significant research interest owing to its ability to discriminate materials, and hence is widely applied in the field of nuclear safety and security inspection. With the current technological developments, DECT can be typically realized by using two sets of detectors, one for detecting lower energy X-rays and another for detecting higher energy X-rays. This makes the imaging system expensive, limiting its practical implementation. In 2009, our group performed a preliminary study on a new low-cost system design, using only a complete data set for lower energy level and a sparse data set for the higher energy level. This could significantly reduce the cost of the system, as it contained much smaller number of detector elements. Reconstruction method is the key point of this system. In the present study, we further validated this system and proposed a robust method, involving three main steps：（1） estimation of the missing data iteratively with TV constraints; （2） use the reconstruction from the complete lower energy CT data set to form an initial estimation of the projection data for higher energy level; （3） use ordered views to accelerate the computation. Numerical simulations with different number of detector elements have also been examined. The results obtained in this study demonstrate that 1 ＋ 14% CT data is sufficient enough to provide a rather good reconstruction of both the effective atomic number and electron density distributions of the scanned object, instead of 2 sets CT data.

关键词： X-ray imaging dual energy CT system sparse samples reconstruction material discriminationAR^TV

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不同尺寸橡胶/帘线H型拉拔试验界面参数的归一化处理评价方法

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Acta Mechanica Sinica 2024年第3期40卷 99-108页

作者：王琮文肖驰代玉静王君马寒松郇勇郇彦 State Key Laboratory of Nonlinear Mechanics(LNM) Institute of MechanicsChinese Academy of SciencesBeijing100190China School of engineering Science University of Chinese Academy of SciencesBeijing100049China School of Aerospace engineering Beijing Institute of TechnologyBeijing100081China State Key Laboratory of Polymer Physics and Chemistry and Polymer Composite engineering Laboratory Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China

H型拉拔试验被广泛应用于橡胶/帘线复合材料界面粘结强度的估算.然而,目前的国际标准只要求在橡胶/帘线H型拉拔试验中记录拔出力的大小,并强调从不同尺寸的样品中获得的结果不具有可比性.在本文中,我们研究了不同尺寸橡胶/帘线试验样品... 详细信息

H型拉拔试验被广泛应用于橡胶/帘线复合材料界面粘结强度的估算.然而,目前的国际标准只要求在橡胶/帘线H型拉拔试验中记录拔出力的大小,并强调从不同尺寸的样品中获得的结果不具有可比性.在本文中,我们研究了不同尺寸橡胶/帘线试验样品的H拔出结果的可比性,并提出了一种归一化的评价方法来处理这些结果.分别对尺寸为5 mm、6.4 mm、10 mm的试验样品进行橡胶/帘线H拉拔试验(尺寸为7.5 mm、8.5 mm的试件结果作为支撑性试验).在试验结果的基础上,采用有限元法内聚单元模型对界面粘结强度进行了分析,所得出的内聚力参数比国际标准中所规定的拔出力更能准确地反映界面粘结性能.因此,采用内聚单元法能够更合理地比较不同橡胶/帘线试样的界面粘结强度.我们首先基于6.4 mm尺寸样品的试验结果建立有限元模型,并确定满足条件的内聚单元参数,然后将其应用于其他尺寸的样品模型.尽管试验样品的尺寸大小在变化,但在保持内聚单元参数不变的前提下,模拟结果与试验结果仍然保持良好的一致性,这表明内聚参数不受样本尺寸的影响.在此基础上,我们提出了一种归一化方法,使不同尺寸样品的橡胶/帘线H拉拔试验的结果具有了可比性.本文提出的归一化方法是对现有国际、国内标准实验方法的扩展.

关键词： Rubber Composites Finite element method Cohesive elements H pull-out test

FGF7 enhances the expression of ACE2 in human islet organoids aggravating SARS-CoV-2 infection

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Signal Transduction and Targeted Therapy 2024年第5期9卷 2260-2274页

作者： Hao Meng Zhiying Liao Yanting Ji Dong Wang Yang Han Chaolin Huang Xujuan Hu Jingyi Chen Hengrui Zhang Zonghong Li Changliang Wang Hui Sun Jiaqi Sun Lihua Chen Jiaxiang Yin Jincun Zhao Tao Xu Huisheng Liu School of Biomedical engineering Guangzhou Medical UniversityGuangzhou 511495 GuangdongChina Guangzhou National Laboratory Guangzhou 510320 GuangdongChina State Key Laboratory of Respiratory Disease National Clinical Research Center for Respiratory DiseaseGuangzhou Institute of Respiratory HealthThe First Affiliated Hospital of Guangzhou Medical UniversityGuangzhou 510120China Center for Translational Medicine Wuhan Jinyintan HospitalWuhan 430023 HubeiChina School of Biomedical Sciences and engineering South China University of TechnologyGuangzhou 510006 GuangdongChina

The angiotensin-converting enzyme 2(ACE2)is a primary cell surface viral binding receptor for SARS-CoV-2,so finding new regulatory molecules to modulate ACE2 expression levels is a promising strategy against *** the current study,we utilized islet organoids derived from human embryonic stem cells(hESCs),animal models and COVID-19 patients to discover that fibroblast growth factor 7(FGF7)enhances ACE2 expression within the islets,facilitating SARS-CoV-2 infection and resulting in impaired insulin *** hESC-derived islet organoids,we demonstrated that FGF7 interacts with FGF receptor 2(FGFR2)and FGFR1 to upregulate ACE2 expression predominantly inβ*** upregulation increases both insulin secretion and susceptibility ofβcells to SARS-CoV-2 *** FGFR counteracts the FGF7-induced ACE2 upregulation,subsequently reducing viral infection and replication in the ***,retrospective clinical data revealed that diabetic patients with severe COVID-19 symptoms exhibited elevated serum FGF7 levels compared to those with mild ***,animal experiments indicated that SARS-CoV-2 infection increased pancreatic FGF7 levels,resulting in a reduction of insulin concentrations in *** together,our research offers a potential regulatory strategy for ACE2 by controlling FGF7,thereby protecting islets from SARS-CoV-2 infection and preventing the progression of diabetes in the context of COVID-19.

关键词： ACE2 FGF7 islet

(Lu_(1/7)Yb_(1/7)Sc_(1/7)Er_(1/7)Y_(1/7)Ho_(1/7)Dy_(1/7))_(2)Si_(2)O_(7)high entropy rare-earth disilicate with low thermal conductivity and excellent resistance to CMAS corrosion

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Journal of Advanced Ceramics 2024年第5期13卷 549-560页

作者： Xu Wang Mingyu Meng Feihan Xu Ling Liu Lihong Gao Shizhen Zhu Zhuang Ma School of Materials Science and engineering Beijing Institute of TechnologyBeijing 100081China National Key Laboratory of Science and Technology on Materials under Shock and Impact Beijing 100081China Tangshan Research Institute Beijing Institute of TechnologyTangshan 063000China

Low thermal conductivity,compatible thermal expansion coefficient,and good calcium–magnesium–aluminosilicate(CMAS)corrosion resistance are critical requirements for environmental barrier coatings used on silicon-based ***2Si2O7(RE=rare earth)has been widely recognized as one of the most promising candidates for environmental barrier coatings due to its good water vapor corrosion ***,the relatively high thermal conductivity and poor resistance to CMAS corrosion have limited its practical *** by the high entropy effect,in this work,a novel rare earth disilicate(Lu_(_(1/7))Yb_(_(1/7))Sc_(_(1/7))Er_(_(1/7))Y_(_(1/7))Ho_(_(1/7))Dy_(_(1/7)))2Si2O7((7RE_(_(1/7)))2Si2O7)has been designed and synthesized by a solid reaction process.(7RE_(_(1/7)))2Si2O7 showed a low thermal conductivity of 1.81 W·m^(−1)·K^(−1)at 1273 ***,the thermal expansion coefficient of(7RE_(_(1/7)))_(2)Si_(2)O_(7)(4.07×10^(−6)℃^(−1)from room temperature(RT)to 1400℃)is close to that of the SiC-based ceramic matrix composites(SiC-CMCs)((4.5–5.5)×10^(−6)℃^(−1)).Additionally,(7RE_(_(1/7)))2Si2O7 exhibited excellent resistance to CMAS *** exposed to CMAS at 1300℃for 48 h,the reaction layer thickness was 22μ*** improved performance of(7RE_(_(1/7)))2Si2O7 highlights its potential as a promising candidate for thermal/environmental barrier coatings.

关键词： high entropy disilicate (Lu_(1/7)Yb_(1/7)Sc_(1/7)Er_(1/7)Y_(1/7)Ho_(1/7)Dy_(1/7))_(2)Si_(2)O_(7)((7RE_(1/7))_(2)Si_(2)O_(7)) high-temperature thermal properties calcium-magnesium-aluminosilicate(CMAS)corrosion

Combining cisplatin and a STING agonist into one molecule for metalloimmunotherapy of cancer

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National Science Review 2024年第1期11卷 107-119页

作者： Shuren Zhang Dongfan Song Wenhao Yu Ji Li Xiaoyu Wang Yachao Li Zihan Zhao Qi Xue Jing Zhao Jie P.Li Zijian Guo State Key Laboratory of Coordination Chemistry School of Chemistry and Chemical EngineeringChemistry and Biomedicine Innovation Center (ChemBIC) Nanjing University Department of Urology Afflliated Drum Tower HospitalMedical SchoolNanjing University Nanchuang (Jiangsu)Institute of Chemistry and Health

Mounting evidence suggests that strategies combining DNA-damaging agents and stimulator of interferon genes(STING) agonists are promising cancer therapeutic regimens because they can amplify STING activation and remodel the immunosuppressive tumor microenvironment. However, a single molecular entity comprising both agents has not yet been developed. Herein, we designed two PtIV-MSA-2 conjugates(Ⅰand Ⅱ) containing the DNA-damaging chemotherapeutic drug cisplatin and the innate immuneactivating STING agonist MSA-2; these conjugates showed great potential as multispecific small-molecule drugs against pancreatic cancer. Mechanistic studies revealed that conjugate Ⅰ upregulated the expression of transcripts associated with innate immunity and metabolism in cancer cells, significantly differing from cisplatin and MSA-2. An analysis of the tumor microenvironment demonstrated that conjugate I could enhance the infiltration of natural killer(NK) cells into tumors and promote the activation of T cells, NK cells and dendritic cells in tumor tissues. These findings indicated that conjugate I, which was created by incorporating a Pt chemotherapeutic drug and STING agonist into one molecule, is a promising and potent anticancer drug candidate, opening new avenues for small-molecule-based cancer metalloimmunotherapy.

关键词： platinum drug STING agonist single-molecule multitarget metalloimmunology

Lead-free perovskites-based photonic synaptic devices with zero electric energy consumption

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Science China(Information Sciences) 2024年第6期67卷 433-441页

作者： Dandan HAO Di YANG Haixia LIANG Jia HUANG Fukai SHAN College of Electronics and Information Qingdao University Key Laboratory of Biofuels Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of Sciences School of Materials Science and engineering Tongji University National Key Laboratory of Autonomous Intelligent Unmanned Systems Tongji University

The von Neumann bottleneck is a critical limitation in synaptic devices. Therefore, artificial synaptic devices resembling biological neuromorphic synapses have been developed to overcome the von Neumann bottleneck. However, synaptic devices require voltages, which results in considerable energy consumption. Here, photonic synaptic devices with the vertical structure of indium tin oxide（ITO）/SnO2/Al2O3/CsBi3I10/Au are fabricated, which can work in the self-powered mode owing to the photovoltaic effect endowed by a vertical multilayer structure. Several fundamental synaptic functions, such as excitatory postsynaptic current, paired-pulse facilitation, short-term plasticity（STP）, long-term plasticity（LTP）, pulse-frequency-dependent plasticity, transition of STP to LTP, and the learning experience are emulated. Moreover, Morse-coded external light information is decoded by self-powered photonic synaptic devices. The results indicate that self-powered photonic synaptic devices based on lead-free perovskites exhibit great potential for efficient neuromorphic computing and optical wireless communication.

关键词： photonic synaptic devices lead-free perovskites zero energy consumption synaptic plasticity Morse code

Multiple-stage spatial-temporal cooperative guidance without time-to-go estimation

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Chinese Journal of Aeronautics 2024年第9期37卷 399-416页

作者： Chunyan WANG Weilin WANG Wei DONG Jianan WANG Fang DENG School of Aerospace engineering Beijing Institute of TechnologyBeijing 100081China National Key Lab of Autonomous Intelligent Unmanned Systems Beiing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

This paper investigates the spatial-temporal cooperative guidance problem for multiple flight vehicles without relying on time-to-go ***,a two-stage cooperative guidance strategy,namely the cooperative guidance and the Proportional Navigation Guidance(PNG)stage strategy,is developed to realize the spatial-temporal constraints in two *** the former stage,two controllers are designed and superimposed to satisfy both impact time consensus and impact angle *** the convergent conditions are satisfied,the flight vehicles will switch to the PNG stage to ensure zero miss *** further extend the results to three dimensions,a planar pursuit guidance stage is additionally imposed at the beginning of *** to the inde-pendence of time-to-go estimation,the proposed guidance strategy possesses great performance in satisfying complex spatial-temporal constraints even under flight speed ***,several numerical simulations are implemented to verify the effectiveness and advantages of the proposed results under different scenarios.

关键词： Cooperative guidance Guided missiles Impact time consensus Impact angle constraint Spatial-temporal cooperative guidance

A novel method for AFRPs burrs removal:Principle of mechanochemo-induced fiber fracture

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Chinese Journal of Aeronautics 2024年第7期37卷 522-538页

作者： Jie XU Bo LI Pingfa FENG Qiang WANG Feng FENG Division of Advanced Manufacturing Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Department of Mechanical engineering Tsinghua UniversityBeijing 100084China Changhe Aircraft Industry(Group)Co.Ltd Jingdezhen 333000China

Burrs generated during the machining of Aramid-Fiber-Reinforced Composites(AFRPs)pose a challenge for the production efficiency of aircraft and helicopter housing *** studies have generally attempted to suppress burrs by referring to delamination suppression *** contrast to stratification,burrs are remediable machining *** such,a mechanochemical method with burrs trimming technological strategy are implemented to effectively combat ***,we clarify the mechanism by which aramid fibers cannot be cut off using analytical and numerical *** addition,the mechanism of fiber fracture with Modified Polyurethane Reactive Polymer(M-PUR),and development of anti-burr devices(thermostatic adhesive sealed generator)are ***,the experimental results show that the reduction rate in burr length is 87%-91%through the mechanochemical *** method not only opens a new avenue to solve the burr problem of aramid fibers but also builds an interdisciplinary bridge between polymer science and composite machining.

关键词： Mechanochemical method Burrs Orthogonal cutting Aramid fiber-reinforced composites Milling

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Ultra-thin robust CNT@GC film integrating effective electromagnetic shielding and flexible Joule heating

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Nano Research 2024年第5期17卷 3462-3471页

作者： Ding Zhang Chunhui Wang Meng Li Weixue Meng Shipeng Zhang Mengdan Yang Xinguang Huang Yingjiu Zhang Yuanyuan Shang Anyuan Cao Key Laboratory of Materials Physics(Ministry of Education) School of Physics and MicroelectronicsZhengzhou UniversityZhengzhou450052China Electron Microscopy Center Yunnan UniversityKunming650091China School of Materials Science and engineering Peking UniversityBeijing100871China

The demand for lightweight,thin electromagnetic interference(EMI)shielding film materials with high shielding effectiveness(SE),excellent mechanical properties,and stability in complex environments is particularly pronounced in the realm of flexible and portable electronic ***,we developed an ultra-thin film(CNT@GC)in which the glassy carbon(GC)layer wrapped around and welded carbon nanotubes(CNTs)to form a core-shell network structure,leading to exceptional tensile strength(327.2 MPa)and electrical conductivity(2.87×10^(5) S·m^(−1)).The CNT@GC film achieved EMI SE of 60 dB at a thickness of 2µm after post-acid treatment and high specific SE of 3.49×10^(5) dB·cm^(2)·g^(−1),with comprehensive properties surpassing those of the majority of previous shielding ***,the CNT@GC film exhibited Joule heating capability,reaching a surface temperature of 135℃at 3 V with a fast thermal response of about 0.5 s,enabling anti-icing/de-icing *** work presented a methodology for constructing a robust CNT@GC film with high EMI shielding performance and exceptional Joule heating capability,demonstrating immense potential in wearable devices,defense,and aerospace applications.

关键词： core-shell structure ultra-thin lightweight film robust film electromagnetic shielding Joule heating