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Universal paradigm of ternary metacomposites with tunable epsilon-negative and epsilon-near-zero response for perfect electromagnetic shielding

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Rare Metals 2024年第2期43卷 796-809页

作者： Yun-Peng Qu Yun-Lei Zhou yang Luo Yao liu jun-Fei Ding Yan-Li Chen Xiu Gong Jing-Liang yang Qiong Peng Xiao-Si Qi College of Physics Guizhou UniversityGuiyang550025China Hangzhou Institute of Technology Xidian UniversityHangzhou311231China Department of Materials ETH Zurich8093ZurichSwitzerland Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJinan250061China

CaCu_(3)Ti_(4)O_(12)(CCTO)ceramic nanocomposites incorporating graphene–carbon black(GRCB)fillers were fabricated by spark plasma sintering *** percolative effects of conductive GRCB fillers on dielectric response of GRCB/CCTO ternary metacomposites were systematically *** weakly real permittivity(ε′)-negative response(ε′~−1×10^(2))was achieved which originated from weakly low-frequency plasmonic state of free carriers within constructed GRCB *** enhancing three-dimensional GRCB network,the plasma frequency of metacomposites increased while the damping factor ***,theε′-negative values of metacomposites were tuned from−10^(2) to−10^(4) orders of magnitude andε′-near-zero(ENZ)frequencies from~142 to~340 MHz which substantially benefited from the moderate carrier concentration of GRCB dual *** Drude model and equivalent circuit models were adopted to demonstrate dielectric and electrical *** obtained metacomposites show strong EM shielding effect along with enhanced plasmonic oscillation and even better achieving perfect EM shielding effect in ENZ *** work achieves the tunableε′-negative andε′-near-zero response and more importantly clarifies its regulation mechanism in ceramic-based ternary metacomposites,which opens up the possibility of designing high-performance EM shielding materials based on metacomposites.

关键词： Metacomposites Ceramic matrix composites Negative permittivity Epsilon-near-zero Electromagnetic shielding

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Review of Sc microalloying effects in Al-Cu alloys

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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 1098-1114页

作者： Shenghua Wu Chong yang Peng Zhang Hang Xue Yihan Gao Yuqing Wang Ruihong Wang Jinyu Zhang Gang liu jun Sun State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China School of Materials Science and Engineering Xi’an University of TechnologyXi’an 710048China School of Aerospace Engineering North University of ChinaTaiyuan 030051China

Artificially controlling the solid-state precipitation in aluminum (Al) alloys is an efficient way to achieve well-performed properties,and the microalloying strategy is the most frequently adopted method for such a *** this paper,recent advances in lengthscale-dependent scandium (Sc) microalloying effects in Al-Cu model alloys are *** coarse-grained Al-Cu alloys,the Sc-aided Cu/Sc/vacancies complexes that act as heterogeneous nuclei and Sc segregation at the θ′-Al_(2)Cu/matrix interface that reduces interfacial energy contribute significantly to θ′*** grain size refinement to the fine/ultrafine-grained scale,the strongly bonded Cu/Sc/vacancies complexes inhibit Cu and vacancy diffusing toward grain boundaries,promoting the desired intragranular θ′*** nanocrystalline scale,the applied high strain producing high-density vacancies results in the formation of a large quantity of (Cu Sc,vacancy)-rich atomic complexes with high thermal stability,outstandingly improving the strength/ductility synergy and preventing the intractable low-temperature *** review recommends the use of microalloying technology to modify the precipitation behaviors toward better combined mechanical properties and thermal stability in Al alloys.

关键词： aluminum alloy microalloying effect length-scale dependence precipitation mechanical properties

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Numerical simulations for radon migration and exhalation behavior during measuring radon exhalation rate with closed-loop method

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Nuclear Science and Techniques 2024年第1期35卷 81-95页

作者： Ming Xia Yong-jun Ye Shu-Yuan liu School of Resources Environment and Safety Engineering University of South ChinaHengyang 421001China Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy University of South ChinaHengyang 421001China

Accurate measurements of the radon exhalation rate help identify and evaluate radon risk regions in the *** these measurement methods,the closed-loop method is frequently ***,traditional experiments are insufficient or cannot analyze the radon migration and exhalation patterns at the gas–solid interface in the accumulation *** CFD-based technique was applied to predict the radon concentration distribution in a limited space,allowing radon accumulation and exhalation inside the chamber intuitively and *** this study,three radon exhalation rates were defined,and two structural ventilation tubes were designed for the *** consistency of the simulated results with the variation in the radon exhalation rate in a previous experiment or analytical solution was *** effects of the vent tube structure and flow rate on the radon uniformity in the chamber;permeability,insertion depth,and flow rate on the radon exhalation rate and the effective diffusion coefficient on back-diffusion were *** on the results,increasing the inser-tion depth from 1 to 5 cm decreased the effective decay constant by 19.55%,whereas the curve-fitted radon exhalation rate decreased(lower than the initial value)as the deviation from the initial value increased by approximately 7%.Increasing the effective diffusion coefficient from 2.77×10^(-7) to 7.77×10^(-6) m^(2) s^(-1) made the deviation expand from 2.14 to 15.96%.The conclusion is that an increased insertion depth helps reduce leakage in the chamber,subject to notable back-diffusion,and that the closed-loop method is reasonably used for porous media with a low effective diffusion coefficient in view of the back-diffusion *** CFD-based simulation is expected to provide guidance for the optimization of the radon exhalation rate measurement method and,thus,the accurate measurement of the radon exhalation rate.

关键词： Radon exhalation Numerical simulation Accumulation chamber

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Endoscopic retrograde appendicitis treatment for periappendiceal abscess: A case report

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World Journal of Clinical Cases 2024年第4期12卷 801-805页

作者： Qiao-Mei Li Bin Ye jun-Wei liu Shang-Wen yang Department of Gastroenterology Lishui Central HospitalThe Fifth Affiliated Hospital of Wenzhou Medical UniversityLishui 323000Zhejiang ProvinceChina

BACKGROUND Acute appendicitis is the most common abdominal *** present,the main treatments for periappendiceal abscess include antibiotics and ***,the complications and mortality of emergency surgery are *** preferred therapy is conservative treatment with antibiotics first,ultrasound-guided puncture drainage or surgical treatment is followed when *** retrograde appendicitis therapy(ERAT)for acute uncomplicated appendicitis have been proved clinically effective,but it is rarely used in periap-pendiceal *** SUMMARY We report a patient admitted to hospital because of“right lower abdominal pain for six days”.The computerized tomography(CT)of patient showed that appendicitis with fecaliths and abscess in the *** patient was treated by CT-guided puncture and drainage of abdominal abscess combined with ERAT to remove appendiceal fecaliths,irrigation and stent *** The patient did not receive surgery because of impoverished *** pain did not recur during the follow-up *** case confirms the value of ERAT in the treatment of periappendiceal abscess.

关键词： Transparent cap Colonoscopy Endoscopic retrograde appendicitis therapy Periappendiceal abscess Case report

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Hot Deformation Behavior of Ti-6Al-4V-0.5Ni-0.5Nb Titanium Alloy

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Journal of Wuhan University of Technology(Materials Science) 2024年第5期39卷 1270-1277页

作者： ZHU Guochuan liu Qiang SONG Shengyin HUI Songxiao YU yang YE Wenjun QI jun TANG Zhengwei XU Penghai CNPC Tubular Goods Research Institute Xi’an 710077China State Key Laboratory for Fabrication&Processing of Nonferrous Metals Beijing General Research Institute for Nonferrous MetalsBeijing 100088China China Petroleum Tarim Oilfield Company Korla 841000China

Characterization of hot deformation behavior of Ti-6Al-4V-0.5Ni-0.5Nb titanium alloy was investigated through isothermal compression at various temperatures from 750 to 1050℃and strain rate from 0.01 to 10 s^(-1).The isothermal compression experiment results showed that the peak stress of Ti-6Al-4V-0.5Ni-0.5Nb titanium alloy decreased with the temperature increasing and the strain rate *** softening mechanism was dynamic recovery below T_(β)and changed to dynamic recrystallization above T_(β).The arrheniustype relationship was used to calculate the constitutive equation of Ti-6Al-4V-0.5Ni-0.5Nb alloy in two-phase *** was found that the apparent activation energies were 427.095 kJ·mol^(-1)in theα+βphase region and 205.451 kJ·mol^(-1)in theβphase region,*** the basis of dynamic materials model,the processing map is generated,which shows that the highest peak efficiency of power dissipation of 56%occurs at about 1050℃/0.01 s^(-1).It can be found in the processing maps that the strain had significant effect on the peak region of power dissipation efficiency of Ti-6Al-4V-0.5Ni-0.5Nb ***,optimized hot working regions were investigated and validated through microstructure *** optimum thermo mechanical process condition for hot working of Ti-6Al-4V-0.5Ni-0.5Nb titanium alloy was suggested to be in the temperature range of 950-1000℃with a strain rate of 0.01-0.1 s^(-1).

关键词： titanium alloy hot deformation processing map dynamic recrystallization

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