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Identifying Three New AGNs among Fermi Unidentified Gigaelectronvolt Sources

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Research in Astronomy and Astrophysics 2024年第7期24卷 260-270页

作者： Shun-Hao Ji Zhong-Xiang wang Qiang-meng Huang Ruo-heng Yang Department of Astronomy School of Physics and AstronomyYunnan University Shanghai Astronomical Observatory Chinese Academy of Sciences

We report our identification of three gigaelectronvolt γ-ray sources, 4FGL J0502.6+0036, 4FGL J1055.9+6507,and 4FGL J1708.2+5519, as Active Galactic Nuclei(AGNs). They are listed in the latest Fermi-Large Area Telescope source catalog as unidentified ones. We find that the sources all showed γ-ray flux variations in recent years. Using different survey catalogs, we are able to find a radio source within the error circle of each source's position. Further analysis of optical sources in the fields allows us to determine the optical counterparts, which showed similar variation patterns to those seen in γ-rays. The optical counterparts have reported redshifts of 0.6,1.5, and 2.3, respectively, estimated from photometric measurements. In addition, we also obtain an X-ray spectrum of 4FGL J0502.6+0036 and a flux upper limit on the X-ray emission of 4FGL J1055.9+6507 by analyzing the archival data. The broadband spectral energy distributions of the three sources from radio to γ-rays are constructed. Comparing mainly the γ-ray properties of the three sources with those of different sub-classes of AGNs, we tentatively identify them as blazars. Followup optical spectroscopy is highly warranted for obtaining their spectral features and thus verifying the identification.

关键词： (galaxies:) BL Lacertae objects: general (galaxies:) quasars: general gamma-rays: galaxies

Corrugated Graphene Paper Reinforced Silicone Resin Composite for Efficient Interface Thermal Management

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Chinese Journal of Polymer Science 2024年第7期42卷 1002-1014,I0010页

作者： Bo-Wen wang heng Zhang Qing-Xia He Hui-Tao Yu meng-meng Qin Wei Feng Tianjin Key Laboratory of Composite and Functional Materials School of Materials Science and EngineeringTianjin UniversityTianjin300350China International Engineering Institute Tianjin UniversityTianjin300350China

With the rapid development of high-power-density electronic devices,interface thermal resistance has become a critical barrier for effective heat management in high-performance electronic ***,there is an urgent demand for advanced thermal interface materials(TIMs)with high cross-plane thermal conductivity and excellent compressibility to withstand increasingly complex operating *** achieve this aim,a promising strategy involves vertically arranging highly thermoconductive graphene on ***,with the currently available methods,achieving a balance between low interfacial thermal resistance,bidirectional high thermal conductivity,and large-scale production is ***,we prepared a graphene framework with continuous filler structures in in-plane and cross-plane directions by bonding corrugated graphene to planar graphene *** interface interaction between the graphene paper framework and polymer matrix was enhanced via surface functionalization to reduce the interface thermal *** resulting three-dimensional thermal framework endows the polymer composite material with a cross-plane thermal conductivity of 14.4 W·m^(-1)·K^(-1)and in-plane thermal conductivity of 130W·m^(-1)·K^(-1)when the thermal filler loading is 10.1 wt%,with a thermal conductivity enhancement per 1 wt%filler loading of 831%,outperforming various graphene structures as *** its high thermal conductivity,low contact thermal resistance,and low compressive modulus,the developed highly thermoconductive composite material demonstrates superior performance in TIM testing compared with TFLEX-700,an advanced commercial TIM,effectively solving the interfacial heat transfer issues in electronic *** novel filler structure framework also provides a solution for achieving a balance between efficient thermal management and ease of processing.

关键词： Graphene paper Vertically aligned structure Cross-plane thermal conductivity Low compressive modulus Thermal interface material

Method for rapid warning and activity concentration estimates in online waterγ-spectrometry systems

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Nuclear Science and Techniques 2024年第3期35卷 1-12页

作者： meng wang Yi Gu Mao-Lin Xiong Liang-Quan Ge Qing-Xian Zhang Guo-Qiang Zeng heng Lu Sheng-Liang Guo College of Nuclear Technology and Automation Engineering Chengdu University of TechnologyChengdu 610059China Applied Nuclear Technology in Geosciences Key Laboratory of Sichuan Province (Chengdu University of Technology)Chengdu 610059China Chengdu New Ray Technology Co.Ltd Chengdu 610052China

Onlineγ-spectrometry systems for inland waters,most of which extract samples in situ and in real time,are able to produce reliable activity concentration measurements for waterborne radionuclides only when they are distributed relatively uniformly and enter into a steady-state diffusion regime in the measurement *** protect residents’health and ensure the safety of the living environment,better timeliness is required for this measurement *** address this issue,this study established a mathematical model of the online waterγ-spectrometry system so that rapid warning and activity estimates can be obtained for water under non-steady-state(NSS)*** addition,the detection efficiency of the detector for radionuclides during the NSS diffusion process was determined by applying the computational fluid dynamics technique in conjunction with Monte Carlo *** this basis,a method was developed that allowed the online waterγ-spectrometry system to provide rapid warning and activity concentration estimates for radionuclides in *** analysis of the NSS-mode measurements of^(40)K radioactive solutions with different activity concentrations determined the optimum warning threshold and measurement time for producing accurate activity concentration estimates for *** experimental results show that the proposed NSS measurement method is able to give warning and yield accurate activity concentration estimates for radionuclides 55.42 and 69.42 min after the entry of a 10 Bq/L^(40)K radioactive solution into the measurement chamber,*** times are much shorter than the 90 min required by the conventional measurement ***,the NSS measurement method allows the measurement system to give rapid(within approximately 15 min)warning when the activity concentrations of some radionuclides reach their respective limits stipulated in the Guidelines for Drinking-water Quality of the WHO,suggesting that this method con

关键词： Water radioactivity monitoring Dynamic detection efficiency Rapid warning Activity estimation

Optimal search path planning of UUV in battlefeld ambush scene

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Defence Technology（防务技术） 2024年第2期32卷 541-552页

作者： Wei Feng Yan Ma heng Li Haixiao Liu Xiangyao meng Mo Zhou Naval Research Institute Beijing100161China

Aiming at the practical application of Unmanned Underwater Vehicle(UUV)in underwater combat,this paper proposes a battlefield ambush scene with UUV considering ocean ***,by establishing these mathematical models of ocean current environment,target movement,and sonar detection,the probability calculation methods of single UUV searching target and multiple UUV cooperatively searching target are given ***,based on the Hybrid Quantum-behaved Particle Swarm Optimization(HQPSO)algorithm,the path with the highest target search probability is ***,through simulation calculations,the influence of different UUV parameters and target parameters on the target search probability is analyzed,and the minimum number of UUVs that need to be deployed to complete the ambush task is demonstrated,and the optimal search path scheme is *** method proposed in this paper provides a theoretical basis for the practical application of UUV in the future combat.

关键词： Battlefield ambush Optimal search path planning UUV path Planning Probability of cooperative search

Enhanced Crystallization of Poly(butylene adipate-co-terephthalate)by a Self-assembly Nucleating Agent

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Chinese Journal of Polymer Science 2024年第5期42卷 663-674,I0010页

作者： Cheng Zhou Kun Chen Zi-heng Zhang meng-Fan Jing Chun-Tai Liu Chang-Yu Shen Ya-Ming wang State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentNational Engineering Research Center for Advanced Polymer Processing TechnologyZhengzhou UniversityZhengzhou450002China

Poly(butylene adipate-co-terephthalate)(PBAT)is a promising biodegradable flexible polymer but suffers from slow crystallization rate,making it less attractive for some applications like the injection-molded products in comparison with low-density polyethylene(LDPE).This work aimed to accelerate the crystallization of PBAT by adding a self-assembly nucleating agent octamethylenedicarboxylic dibenzoylhydrazide(OMBH).PBAT/OMBH composites with various OMBH contents(0 wt%,0.5 wt%,0.7 wt%,1 wt%,2 wt%,3 wt%and 5 wt%)were prepared through *** effect of OMBH on the crystallization behavior,morphologies and mechanical properties of PBAT was *** highest nucleation efficiency value of 59.6%was achieved for PBAT with 0.7 wt%OMBH,much higher than that of 22.7%for PBAT with 0.7 wt%*** force microscopy results showed that OMBH formed fine fibers and induced the formation of transcrystalline layers of *** transform infrared spectroscopy(FTIR)combined with two-dimensional correlation spectra suggested that the intermolecular dipole-dipole N—H…O=C interactions but not hydrogen bond between OMBH and PBAT promoted the crystallization of PBAT in the initial period of *** presence of OMBH did not change the crystal form of PBAT but had positive contribution in enhancing its crystallinity and mechanical *** work is essential for preparing PBAT with high crystallization rate,enhancing its potential applications in injection-molded products.

关键词： Poly(butylene adipate-co-terephthalate) Biodegradable Self-assembly nucleating agent Crystallization

Algorithm of automatic identification of diabetic retinopathy foci based on ultra-widefield scanning laser ophthalmoscopy

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International Journal of Ophthalmology(English edition) 2024年第4期17卷 610-615页

作者： Jie wang Su-Zhen wang Xiao-Lin Qin meng Chen heng-Ming Zhang Xin Liu meng-Jun Xiang Jian-Bin Hu Hai-Yu Huang Chang-Jun Lan Aier Eye Hospital(East of Chengdu) Chengdu 610051Sichuan ProvinceChina Department of Ophthalmology Chengdu First People’s HospitalChengdu 610095Sichuan ProvinceChina School of Computer and Artificial Intelligence Southwest Jiaotong UniversityChengdu 610097Sichuan ProvinceChina Chengdu Aier Eye Hospital Chengdu 610041Sichuan ProvinceChina

AIM:To propose an algorithm for automatic detection of diabetic retinopathy(DR)lesions based on ultra-widefield scanning laser ophthalmoscopy(SLO).METHODS:The algorithm utilized the FasterRCNN(Faster Regions with CNN features)+ResNet50(Residua Network 50)+FPN(Feature Pyramid Networks)method for detecting hemorrhagic spots,cotton wool spots,exudates,and microaneurysms in DR ultra-widefield *** segmentation combined with a deeper residual network FasterRCNN+ResNet50 was employed for feature extraction to enhance intelligent learning *** fusion was carried out by the feature pyramid network FPN,which significantly improved lesion detection rates in SLO fundus ***:By analyzing 1076 ultra-widefield SLO images provided by our hospital,with a resolution of 2600×2048 dpi,the accuracy rates for hemorrhagic spots,cotton wool spots,exudates,and microaneurysms were found to be 87.23%,83.57%,86.75%,and 54.94%,***:The proposed algorithm demonstrates intelligent detection of DR lesions in ultra-widefield SLO,providing significant advantages over traditional fundus color imaging intelligent diagnosis algorithms.

关键词： diabetic retinopathy ultra-widefield scanning laser ophthalmoscopy intelligent diagnosis system

General radical difluoromethylation using difluoroacetic anhydride via photoredox catalysis

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Science China Chemistry 2024年第8期67卷 2637-2646页

作者： meng He Yankai Yang heng Zhang Zhipeng Guan Zhi-Bing Dong Hong Yi Aiwen Lei School of Chemistry and Environmental Engineering Wuhan Institute of TechnologyWuhan 430205China College of Chemistry and Molecular Sciences and Institute for Advanced Studies(IAS) Wuhan UniversityWuhan 430072China

CF_(2)H-containing molecules play pivotal roles in diverse fields from medicinal chemistry to materials science. However, the application of existing CF_(2)H reagents as a source of CF_(2)H radical is limited by their reactivity and preparation. Herein, we develop a simple and general visible-light-catalyzed radical difluoromethylation reaction of alkenes, dienes, and heteroaromatics using commercially available, easy-to-handle, and low-cost difluoroacetic anhydride as the CF_(2)H reagent. This scalable protocol enables the convenient synthesis of a range of CF_(2)H-containing compounds under mild conditions, exhibiting a broad substrate scope and functional group tolerance. Potential applications are further demonstrated by gram-scale synthesis, sunlight experiments, derivatization experiments as well as the synthesis of bioactive molecules.

关键词： radical difluoromethylation alkenes/dienes/heteroaromatics difluoroacetic anhydride photoredox

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Grain growth behavior and properties of high-entropy pseudobrookite(Mg,Co,Ni,Zn)Ti_(2)O_(5) ceramics

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Journal of Advanced Ceramics 2024年第6期13卷 757-768页

作者： Xiaohui Ma Jinyu Wu Lingyi meng Jinfeng Zhang heng Chen Liwen Yan Anran Guo Jiachen Liu Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education School of Materials Science and EngineeringTianjin UniversityTianjin 300072China Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi InstitutesChinese Academy of SciencesXiamen 361021China

It is well known that the grain size of high-entropy ceramics is quite small owing to the sluggish diffusion effect. However, abnormal grain growth often occurs in high-entropy pseudobrookite ceramics, ultimately resulting in the formation of many abnormally grown grains with a grain size as large as 50 μm. To study this phenomenon, the grain growth behavior of high-entropy pseudobrookite ceramics was systematically investigated in this paper. The results demonstrate that the starting material powders first react with each other to form a high-entropy intermediate phase and calcined TiO_(2) powders (TiO_(2)-1100 ℃), and then as the sintering temperature increases, the formed high-entropy intermediate phase further reacts with TiO_(2)-1100 ℃ to form high-entropy pseudobrookite ceramics. Thus, in this system, in addition to the sluggish diffusion effect, the grain sizes of the high-entropy intermediate phase and TiO_(2)-1100 ℃ also affect the morphology of high-entropy pseudobrookite. Compared to nanosized TiO_(2), micron-sized TiO_(2) has a lower sintering activity. Therefore, the high-entropy intermediate phases (Mg,Co,Ni,Zn)TiO_(3) and TiO_(2)-1100 ℃ prepared with micron-sized starting materials exhibit lower grain sizes, finally resulting in the formation of high-entropy (Mg,Co,Ni,Zn)Ti_(2)O_(5) with small grain sizes. Moreover, nano-indentation and thermal conductivity tests were carried out on high-entropy (Mg,Co,Ni,Zn)Ti_(2)O_(5) with different morphologies. The results show that the hardness of high-entropy (Mg,Co,Ni,Zn)Ti_(2)O_(5) increases from 6.05 to 9.95 GPa as the grain size increases, whereas the thermal conductivity decreases from 2.091±0.006 to 1.583±0.006 W·m^(−1)·K^(−1). All these results indicate that high-entropy (Mg,Co,Ni,Zn)Ti_(2)O_(5) with a small grain size is a potential material for thermal protection.

关键词： grain size sluggish diffusion effect two-step solid phase process high-entropy intermediate phase high-entropy pseudobrookite ceramic

Mechanism and control of nonuniform phase transformation of microalloyed dual-phase steel during cooling process after hot rolling

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Journal of Iron and Steel Research(International) 2024年第2期31卷 428-441页

作者： Wen-quan Sun Sheng-yi Yong Tie-heng Yuan Chao Liu San-bao Zhou Rui-chun Guo meng-xia Tang National Engineering Research Center for Advanced Rolling and Intelligent Manufacturing University of Science and Technology BeijingBeijing100083China Strip Production Plant Xichang Steel and Vanadium Corporation of Pangang GroupXichang615000SichuanChina

After cooling in the hot rolling process,the metallographic structure of microalloyed dual-phase steel is nonuniform along the rolling direction,while the thickness fluctuation of microalloyed dual-phase steel with a nonuniform metallographic structure will occur during cold *** mechanism of nonuniform phase transformation of microalloyed dual-phase steels was studied during the cooling process after hot rolling,and the nonuniform phase transformation of microalloyed dual-phase steel was regulated during the cooling process after hot rolling through process ***,the empirical equation of phase transformation temperature was measured by a dilatometer considering thermal ***,the phase field and temperature field of laminar cooling process were calculated to provide initial boundary conditions for the finite element *** that,the coupling finite element model of the temperature phase transformation of the strip steel in coiling transportation process was *** simulation results show that the different thermal contact conditions of the microalloyed dual-phase steel during coil transportation lead to uneven cooling of the coil,which leads to nonuniform transformation of the coil along the rolling *** addition,by prolonging the time interval from coiling to unloading,the phenomenon of nonuniform phase transformation of microalloyed dual-phase steel can be effectively *** simulation results are applied to industrial *** application results show that prolonging the time interval from coiling to unloading can effectively improve the nonuniform phase transformation of microalloyed dual-phase steel in the cooling process after hot rolling.

关键词： Microalloyed dual-phase steel Thickness fluctuation Cooling Heat conduction Nonuniform phase transition Finite element method