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Effect of fluoride on the corrosion behavior of nanostructured Ti-24Nb-4Zr-8Sn alloy in acidulated artificial saliva

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Journal of Materials Science & Technology 2018年第9期34卷 1660-1670页

作者： Ji Li Yun Bai Zhidong Fan Shujun Li Yulin Hao Rui Yang Yongbo Gao Xi'an Thermal Power Research Institute Co. Ltd. Xi'an 710032 China Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Stomatology Longgang District Central Hospital Affiliated to Zunyi Medical College Shenzhen 518116 China

The surface of titanium dental implants is highly susceptible to aggressive fluoride ions in the oral environment. Nanotechnology has proven an effective approach to improve the stability and corrosion resistance of titanium by applying a passive film. In this study, we investigated the effects of fluoride on the corrosion behavior of nanostructured（NS） Ti-24 Nb-4 Zr-8 Sn（Ti2448） alloy in acidulated artificial saliva（AAS）at 37 ℃, and then conducted comparisons with its coarse grained（CG） counterpart. Electrochemical techniques, such as potentiodynamic polarization and electrochemical impedance spectroscopy（EIS）, as well as surface analysis including X-ray photoelectron spectroscopy（XPS） with argon ion sputtering, and scanning electronic microscopy（SEM） were employed to evaluate the effects of fluoride on sensitivity to pitting and the tolerance of Ti2448 to fluoride in AAS solution. The results demonstrate that corrosion current density increased with F-concentration. In all respects, the NS Ti2448 alloy presented corrosion resistance superior to that of its coarse grained（CG） counterpart at low F-concentrations（0.1%）.Furthermore, a high content of F-（1%） was shown to promote the active dissolution of both alloys by increasing the rate of corrosion. Following immersion in the fluoridated AAS solution for 60 days, a tissuefriendly compound, Ca3（PO4）2, was detected on the surface of the NS when F-= 0.01% and Na2 TiF6 was identified as the main component in the corrosion products of the CG as well as NS Ti2448 alloys when F-= 1%. High concentrations of F-produced pitting corrosion on the CG alloy, whereas NS Ti2448 alloy presented general corrosion in the form of lamellar separation under the same conditions. These findings demonstrate the superior corrosion resistance of the NS Ti2448 alloy as well as lower pitting sensitivity and higher tolerance to fluoride due mainly to grain refinement.

关键词： Titanium Fluoride Corrosion Nanostructuring Ti2448

In-orbit performance of LE onboard Insight-HXMT in the first 5 years

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Radiation Detection Technology and Methods 2023年第1期7卷 25-33页

作者： Xiaobo Li Yong Chen Liming Song Weiwei Cui Wei Li Juan Wang Shuang-Nan Zhang Fangjun Lu Yupeng Xu Haisheng Zhao Mingyu Ge Youli Tuo Yusa Wang Tianxiang Chen Dawei Han Jia Huo Yanji Yang Maoshun Li Ziliang Zhang Yuxuan Zhu Xiaofan Zhao Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of Science19B Yuquan RoadShijingshan DistrictBeijing 100049China

Purpose The low-energy X-ray telescope(LE)is a main instrument of the Insight-HXMT mission and consists of 96 swept charge devices covering the 1–10 keV energy *** energy gain and resolution are continuously calibrated by analyzing Cassiopeia A(Cas A)and blank sky data,while the effective areas are also calibrated with the observations of the Crab *** this paper,we present the evolution of the in-orbit performances of LE in the first 5 years since *** The Insight-HXMT data analysis software package(HXMTDAS)is utilized to extract the spectra of Cas A,blank sky,and Crab Nebula using different good time interval *** fit a model with a power-law continuum and several Gaussian lines to different ranges of Cas A and blank sky spectra to get peak energies of their lines through *** updating the energy gain calibration in CALibration DataBase(CALDB),we rerun the Cas A data to obtain the energy *** empirical function is used to modify the simulated effective areas so that the background-subtracted spectrum of the Crab Nebula can best match the standard model of the Crab *** The energy gain,resolution,and effective areas are calibrated every *** corresponding calibration results are duly updated in CALDB,which can be downloaded and used for the analysis of Insight-HXMT *** observations with NuSTAR and NICER can also be used to verify our derived *** LE is a well-calibrated X-ray telescope working in 1–10 keV *** uncertainty of LE gain is less than 20eV in 2–9 keV band,and the uncertainty of LE resolution is less than *** systematic errors of LE,compared to the model of the Crab Nebula,are lower than 1.5%in 1–10 keV.

关键词： X-ray Calibration SCD In-orbit performance

In-orbit performance of ME onboard Insight-HXMT in the first 5 years

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Radiation Detection Technology and Methods 2023年第1期7卷 15-24页

作者： Ying Tan Xuelei Cao Weichun Jiang Xiaobo Li Bin Meng Wanchang Zhang Sheng Yang Tao Luo Yudong Gu Liang Sun Xiaojing Liu Yuanyuan Du Jiawei Yang Yanjun Xu Jinyuan Liao Yupeng Xu Fangjun Lu Liming Song Shuangnan Zhang Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of Science19B Yuquan RoadShijingshan DistrictBeijing 100049China

Introduction The medium-energy X-ray telescope(ME)is a collimated X-ray telescope onboard the Insight hard X-ray modulation telescope(Insight-HXMT)*** has 1728 Si-PIN pixels readout using 54 low noise application-specific integrated circuits(ASICs).ME covers the energy range of 5–30 keV and has a total detection area of *** typical energy resolution of ME at the beginning of the mission is 3 keV at 17.8 keV(full width at half maximum,FWHM),and the time resolution is 255μ*** this study,we present the in-orbit performance of ME in its first 5 years of *** The performance of ME was monitored using onboard radioactive sources and astronomical X-ray *** carries six 241Am radioactive sources for onboard calibration,which can continuously illuminate the calibration *** long-term performance evolution of ME can be quantified using the properties of the accumulated spectra of the calibration *** addition,observations of the Crab Nebula and the pulsar were used to check the long-term evolution of the detection efficiency as a function of *** After 5 years of operation,742cm2 of the Si-PIN pixelswere stillworking *** peak positions of 241Am emission lines gradually shifted to the high-energy region,implying a slow increase in ME gain of 1.43%.A comparison of the ME spectra of the Crab Nebula and the pulsar shows that the E–C relations and the redistribution matrix file are still acceptable for most data analysis works,and there is no detectable variation in the detection efficiency.

关键词： Hard X-ray Calibration Detector In-orbit performance

Vertical distribution of aerosol optical properties based on aircraft measurements over the Loess Plateau in China

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Journal of Environmental Sciences 2015年第8期27卷 44-56页

作者： Junxia Li Xingang Liu Liang Yuan Yan Yin Zhanqing Li Peiren Li Gang Ren Lijun Jin Runjun Li Zipeng Dong Yiyu Li Junmei Yang Weather Modification Office of Shanxi Province Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration Nanjing University of Information Science and Technology State Key Laboratory of Water Environment Simulation School of Environment Beijing Normal University College of Global Change and Earth System Science Beijing Normal University Meteorological Institute of Shaanxi Province

Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four flights were analyzed. The vertical distributions of aerosol optical properties including aerosol scattering coefficients（σsc）, absorption coefficients（σab）,Angstr？m exponent（α）, single scattering albedo（ω）, backscattering ratio（βsc）, aerosol mass scattering proficiency（Q sc） and aerosol surface scattering proficiency（Q sc′） were obtained. The mean statistical values of σsc were 77.45 Mm-1（at 450 nm）, 50.72 Mm-1（at 550 nm）, and32.02 Mm-1（at 700 nm）. The mean value of σab was 7.62 Mm-1（at 550 nm）. The mean values ofα, βsc and ω were 1.93, 0.15, and 0.91, respectively. Aerosol concentration decreased with altitude. most effective diameters（ED） of aerosols were less than 0.8 μm. The vertical profiles of σsc,, α, βsc, Q sc and Q sc′ showed that the aerosol scattering properties at lower levels contributed the most to the total aerosol radiative forcing. Both α and βsc had relatively large values, suggesting that most aerosols in the observational region were small particles. The mean values of σsc, α, βsc, Q sc, Q sc′, σab and ω at different height ranges showed that most of the parameters decreased with altitude. The forty-eight hour backward trajectories of air masses during the observation days indicated that the majority of aerosols in the lower level contributed the most to the total aerosol loading, and most of these particles originated from local or regional pollution emissions.

关键词： Vertical distribution Optical properties Aircraft measurements The Loess Plateau

Fatigue properties of titanium alloy custom short stems fabricated by electron beam melting

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Journal of Materials Science & Technology 2020年第17期52卷 180-188页

作者： Liao Wang Shujun Li Mengning Yan Yubo Cheng Wentao Hou Yiping Wang Songtao Ai Rui Yang Kerong Dai Shanghai Key Laboratory of Orthopaedic Implants Department of Orthopaedic SurgeryShanghai Ninth People’s HospitalShanghai Jiao Tong University School of MedicineShanghai Jiao Tong UniversityShanghai 200030China Titanium Alloy Laboratory Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Image Medraw Technology(Shanghai)Company Limited Shanghai 201100China

The fatigue properties of titanium alloy short-stems with four different lengths,manufactured by electron beam melting(EBM)technology,were investigated by in vitro test and finite element(FE)*** simulation results indicate that the maximum tensile stress concentrates at the lateral side of the stem *** magnitude of the concentrated tensile stress increases and the corresponding area of the axial section decreases with increasing of stem *** from fatigue tests demonstrate that fatigue cracks mainly initiate from the rough surface of the stem where the maximum tensile stress *** fatigue strength decreases with the increase of stem length,which is attributed to the higher stress concentration on the longer stem *** addition,it is found that post EBM treatment via hot isostatic processing(HIP)is able to enhance the fatigue properties of the stems,since the pores generated during EBM are mostly closed during *** work also demonstrates that the stress concentration on the stem surface can be effectively mitigated and the corresponding fatigue properties of the EBM-fabricated titanium alloy short stem can be considerably improved by optimizing the design in the stem length.

关键词： Custom short stem Titanium alloy Electron beam melting Fatigue property

Reflections and standing waves on the Tianlai cylinder array

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Research in Astronomy and Astrophysics 2021年第3期21卷 73-85页

作者： Ji-Xia Li Feng-Quan Wu Shi-Jie Sun Zi-Jie Yu Shi-Fan Zuo Ying-Feng Liu You-Gang Wang Cong Zhang Reza Ansari Peter Timbie Xuelei Chen National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Center for Astrophysics and Department of Astronomy Tsinghua UniversityBeijing 100084China IJC Lab CNRS/IN2P3&Universite Paris-Saclay15 rue Georges Cl´emenceau91405 OrsayFrance´ Department of Physics University of Wisconsin Madison1150 University AveMadison WI 53703USA Center of High Energy Physics Peking UniversityBeijing 100871China

In 21 cm intensity mapping,the spectral smoothness of the foreground is exploited to separate it from the much weaker 21 cm ***,the non-smooth frequency response of the instrument complicates this *** and standing waves generate modulations on the frequency *** we report the analysis of the standing waves in the bandpass of the signal channels of the Tianlai Cylinder *** Fourier transforming the bandpass into the delay time domain,we find various standing waves generated on the telescope.A standing wave with time delay at~142 ns is most clearly identified which is produced in the 15-meter feed *** also identify a strong peak at a shorter delay ofτpartially recovered by removing the reflection-inducted ***,the standing wave on the antenna is direction-dependent,which poses a more difficult challenge for high precision calibration.

关键词： techniques:interferometric methods:data analysis

Insight-HXMT on-orbit thermal control status and thermal deformation impact analysis

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Radiation Detection Technology and Methods 2023年第3期7卷 337-349页

作者： Ai-Mei Zhang Yi-Fan Zhang Jin-Yuan Liao Yu-Peng Xu Yu-Sa Wang Wen-Bo Luo Yu-Peng Zhou Zhi-Ying Qian Xiao-Bo Li Fang-Jun Lu Shuang-Nan Zhang Li-Ming Song Cong-Zhan Liu Fan Zhang Jian-Yin Nie Juan Wang Sheng Yang Tong Zhang Xiao-Jing Liu Rui-Jie Wang Xu-Fang Li Yi-Fei Zhang Zheng-Wei Li Xue-Feng Lu He Xu Di Wu Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of chinese Academy of Sciences Chinese Academy of SciencesBeijing 100049China Beijing Institute of Spacecraft System Engineering CASTBeijing 100094China

Purpose The Hard X-ray Modulation Telescope is China’s first X-ray astronomy satellite launched on June 15,2017,dubbed *** and passive thermal control measures are employed to keep devices at suitable *** this paper,we analyzed the on-orbit thermal monitoring data of the first 5 years and investigated the effect of thermal deformation on the point spread function(PSF)of the *** We examined the data of the on-orbit temperatures measured using 157 thermistors placed on the collimators,detectors and their support structures and compared the results with the thermal control *** thermal deformation was evaluated by the relative orientation of the two star sensors installed on the main support *** effect was estimated with evolution of the PSF obtained with calibration scanning observations of the Crab *** The on-orbit temperatures met the thermal control requirements thus far,and the effect of thermal deformation on the PSF was negligible after the on-orbit pointing calibration.

关键词： X-ray Insight-HXMT Thermal control Temperature Star sensor data Pointing PSF

A Privacy-Preserving Attribute-Based Reputation System in Online Social Networks

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Journal of Computer Science & Technology 2015年第3期30卷 578-597页

作者：郭霖珂张驰方玉光林风 Department of Electrical and Computer Engineering Binghamton University Binghamton NY 13902 U.S.A. CAS Key Laboratory of Electromagnetic Space Information University of Science and Technology of China Hefei 230026 China Department of Electrical and Computer Engineering University of Florida GainesviUe FL 32611 U.S.A. Department of Computer Science and Information Engineering 'National' Taiwan University Taipei 10617 China

Online social networks （OSNs） have revolutionarily changed the way people connect with each other. One of the main factors that help achieve this success is reputation systems that enable OSN users to mutually establish trust relationships based on their past experience. Current approaches for the reputation management cannot achieve the fine granularity and verifiability for each individual user, in the sense that the reputation values on such OSNs are coarse and lack of credibility. In this paper, we propose a fine granularity attribute-based reputation system which enables users to rate each other＇s attributes instead of identities. Our scheme first verifies each OSN user＇s attributes, and further allows OSN users to vote on the posted attribute-associated messages to derive the reputation value. The attribute verification process provides the authenticity of the reputation value without revealing the actual value to entities who do not have the vote privilege. To predict a stranger＇s behavior, we propose a reputation retrieval protocol for querying the reputation value on a specific attribute. To the best of our knowledge, we are the first to define a fine-grained reputation value based on users＇ verified attributes in OSNs with privacy preservation. We provide the security analysis along with the simulation results to verify the privacy preservation and feasibility. The implementation of the proposed scheme on current OSNs is also discussed.

关键词： reputation privacy attribute authentication

Serosurvey of Avian metapneumovirus, Orithobacterium rhinotracheale, and Chlamydia psittaci and Their Potential Association with Avian Airsacculitis

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Biomedical and Environmental Sciences 2018年第5期31卷 403-406页

作者： ZUO Zong Hui ZHANG Tian Yuan GUO Yong Xia CHU Jun QU Guang Gang MIAO Li Zhong SHEN Zhi Qiang HE Cheng Key Lab of Animal Epidemiology and Zoonosis of Ministry of Agriculture ChinaCollege of Veterinary MedicineChina Agricultural UniversityBeijing 100193China Shandong Binzhou Animal Science and Veterinary Medicine Academy Binzhou 256600ShandongChina

Seasonal outbreaks of airsacculitis in China＇s poultry cause great economic losses annually. This study tried to unveil the potential role of Avian metopneumovirus （AM PV）, Ornithobacterium rhinotrocheale （aRT） and Chlarnydia psittaci （CPS） in avian airsacculitis. A serological investigation of 673 breeder chickens and a case-controlled study of 430 birds were undertaken. Results showed that infection with AMPV, aRT, and CPS was highly associated with the disease. The correlation between AMPV and CPS were positively robust in both layers and broilers. Finally, we determined the co-infection with AMPV, aRT, and CPS was prevalent in the sampled poultry farms suffering from respiratory diseases and the outbreak of airsacculitis was closely related to simultaneous exposure to all three agents.

关键词： ORT CPS Serosurvey of Avian metapneumovirus,Orithobacterium rhinotracheale,and Chlamydia psittaci and Their Potential Association with Avian Airsacculitis