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Multifunctional protective aerogel with superelasticity over−196 to 500℃

Nano Research 2022年第9期15卷 7797-7805页

作者： Bo-Wen Liu min Cao Yi-Ying Zhang Yu-Zhong wang hai-Bo Zhao The Collaborative Innovation Center for Eco-Friendly and Fire-Safety Polymeric Materials(MoE) National Engineering Laboratory of Eco-Friendly Polymeric Materials(Sichuan)State Key Laboratory of Polymer Materials EngineeringCollege of ChemistrySichuan UniversityChengdu 610064China

Protective materials that possess superelasticity and multifunctionality over a broad temperature range are urgently needed in various advanced ***,under harsh work conditions,the performance of current materials may largely deteriorate to lose protective ***,we report a bidirectionally oriented multi-walled carbon nanotubes(MWCNTs)-reinforced chitosan carbon aerogel(CS-MWCNT)that possesses superelasticity,high electromagnetic interference shielding,thermal insulation,and infrared stealth at both low temperatures(such as liquid nitrogen)and high temperatures(such as alcohol flames).Highly oriented lamellar arch structures combined with an MWCNTs-reinforced carbon skeleton act as elastic segments to disperse the stress during compression and endow CS-MWCNT with the ability to recover to almost the original size after being compressed at−196-500℃.The lamellar structures make CS-MWCNT thermally insulating and infrared stealth with a low thermal conductivity of~0.03 W/(m·K).Furthermore,a high electromagnetic interference(EMI)shielding effect of 64 dB is realized via an absorption-dominant EMI shielding mechanism derived from the successive inherently conductive carbon lamella,and the EMI shielding performance is largely maintained after treatment under extreme conditions like low temperature,high temperature,as well as cyclic *** work provides a new strategy for the development of temperature-invariant multifunctional aerogels for harsh environment applications.

关键词： superelasticity electromagnetic interference shielding heat insulation infrared stealth extreme environment

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min-max load balancing scheme for mixed multicast and unicast services in LTE networks

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The Journal of China Universities of Posts and Telecommunications 2012年第2期19卷 30-35页

作者： wang min FENG Chun-yan ZHANG Tian-kui School of Information and Communication Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China

To avoid the traffic congestion in long term evolution （LTE） networks, a min-max load balancing （LB） scheme is proposed to minimize the demanded radio resources of the maximum loaded cell. For the mixed multicast and unicast services, multicast services are transmitted by single frequency network （SFN） mode and unicast services are delivered with point-to-point （PTP） mode. The rain-max LB takes into account point-to-multipoint （PTM） mode for multicast services and selects the proper transmission mode between SFN and PTM for each multicast service to minimize the demanded radio resources of the maximum loaded cell. Based on the solution of this minimization problem, if the maximum loaded cell does not overload, the min-max LB will change PTM mode into SFN mode for mulficast services to achieve high quality of service （QoS）. Simulation results show that the proposed miu-max LB scheme requires less radio resources from the maximum loaded cell than SFN mode for all multicast services.

关键词： multicast and broadcast single frequency network load balancing point-to-multipoint quality of service

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Upcycling of polyethylene terephthalate to1,4-cyclohexanedimethanol in water

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Science China Chemistry 2025年

作者： Shuhui Fang Zhiwen Gao Xinrui Shi min Zhang Wei Zhang Yue Liu State Key Laboratory of Petroleum Molecular & Process Engineering Shanghai Key Laboratory of Green Chemistry and Chemical ProcessesSchool of Chemistry and Molecular Engineering East China Normal University Engineering Center for Sustainable Carbon Science and Technology East China Normal University Institute of Eco-Chongming

The recycling of waste polyethylene terephthalate（PET）, an extensively used polymer as plastic and fiber materials, has become an urgent topic due to the rapid generation and accumulation of plastic waste into the environment. Current chemical recycling approaches to depolymerize and convert PET into 1,4-cyclohexanedimethanol（CHDM）, an important chemical in the production of advanced polyesters, predominantly use organic solvents, such as alcohols or dioxane. Herein, we developed an environmentally friendly and economically viable pathway for converting PET to CHDM using water as the solvent. In this process, PET is sequentially hydrolyzed in water, hydrogenated to 1,4-cyclohexane dicarboxylic acid（CHDA）, and then reduced to CHDM. The PET conversion rate is self-enhanced in aqueous medium via acid-catalyzed hydrolysis by the generated CHDA intermediate. A Pd-based catalyst（e.g., Pd/C） selectively hydrogenates the arene ring of the PET monomer, terephthalic acid intermediate, and a Ru-Sn/C bimetallic catalyst reduces its COOH to CH2OH group. At optimized reaction conditions, a complete conversion of PET and 80.1% yield of CHDM are obtained. Alternatively, this approach can also efficiently produce CHDA from PET, with a yield up to 86.4%.

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Friction and Wear Behavior of AlTiN-Coated Carbide Balls Against SKD11 Hardened Steel at Elevated Temperatures

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Acta Metallurgica Sinica(English Letters) 2018年第10期31卷 1073-1083页

作者： Rui wang hai-Juan Mei Ren-Suo Li Quan Zhang Teng-Fei Zhang Qi-min wang School of Electromechanical Engineering Guangdong University of Technology Guangzhou 510006 China School of Mechanical Engineering Guilin University of Aerospace Technology Guilin 541004 China

In this study, AlTiN coatings were deposited on YT14 cemented carbide balls by arc ion plating technique. The friction and wear behavior of the AlTiN-coated balls against SKD11 hardened steel was investigated by sliding tests using a ball-ondisk tribometer at various temperatures from 25 to 700 ℃ in air. The results showed that the friction and wear behavior was significantly influenced by the testing temperature. Obvious fluctuations were observed in the friction curves at elevated temperatures, which could be attributed to the formation and rupture of unstable Fe and Cr oxide layers. As the temperature increased from 25 to 500 ~C, the wear rate of the coated balls increased from the scale of 10-21-10-20 m3/ N m, and then decreased to 10-22 m3/N m as the temperature further increased to 700℃. It was also found that the friction and wear behavior of the coated balls was directly dependent on the counterpart materials. As the temperature increased, the main wear mechanism of the coated balls changed from mild abrasive wear and adhesive wear to abrasive wear failure at 500℃, and then transferred to adhesive wear and mild oxidation wear at 700℃. For SKD11 hardened steel, the primary wear mechanism changed from delamination wear to abrasive wear and then transferred to plastic deformation and fatigue wear, accompanied by adhesive wear and tribo-oxidation wear.

关键词： AlTiN. SKD11 hardened steel. Elevated temperatures Friction and wear

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Strain transfer of surface-bonded fiber Bragg grating sensors for airship envelope structural health monitoring

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第7期13卷 538-545页

作者： hai-tao ZHAO Quan-bao wang Ye QIU Ji-an CHEN Yue-ying wang Zhen-min FAN School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China

This paper deals with an improved bonding approach of surface-bonded fiber Bragg grating (FBG) sensors for airship envelope structural health monitoring (SHM) under the strain transfer theory. A theoretical formula is derived from the proposed model to predict the strain transfer relationship between the airship envelope and fiber core. Then theoretical predictions are validated by numerical analysis using the finite element method (FEM). Finally, on the basis of the theoretical approach and numerical validation, parameters that influence the strain transfer rate from the airship envelope to fiber core and the ratio of effective sensing length are analyzed, and some meaningful conclusions are provided.

关键词： Airship envelope Fiber Bragg grating (FBG) Surface-bonded Strain transfer Structural health monitoring (SHM)

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Numerical design optimization of compressor blade based on ADOP

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航空动力学报 2007年第11期22卷 1903-1908页

作者： JIN Dong-hai GUI Xing-min School of Jet Propulsion Beijing University of Aeronautics and Astronautics Beijing 100083 China

An aerodynamic design optimization platform(ADOP) has been *** numerical optimization method is based on genetic algorithm(GA),Pareto ranking and fitness sharing *** platform was used for design optimization of the stator of an advanced transonic stage to seek high adiabatic *** compressor stage efficiency is increased by 0.502% at optimal point and the stall margin is enlarged by nearly 1.0% at design rotating *** flow fields of the transonic stage were simulated with FINE/Turbo software *** optimization result indicates that the optimization platform is effective in 3D numerical design optimization problems.

关键词：最优化设计压缩机桨片空气动力学 ADOP 遗传算法

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Extractable Fractions of Metals in Sewage Sludges from Five Typical Urban Wastewater Treatment Plants of China

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Pedosphere 2006年第6期16卷 756-761页

作者： wang Chao LI Xiao-Chen wang Pei-Fang ZOU Li-min MA hai-Tao Key Laboratory of Integrated Regulation and Resource Department on Shallow Lakes Ministry of Education Nanjing 210098 China School of Environmental Science and Engineering Hohai University Nanjing 210098 China

Metal content and bioavailability are often the limiting factors for application of sewage sludge in agricultural fields. Sewage sludge samples were collected from five typical urban wastewater treatment plants in China to investigate their contents and distribution of various chemical fractions of Cu, Zn, Ni, Cr, Pb and Mo by using the BCR （Community Bureau of Reference） sequential extraction procedure. The sludges contained considerable amounts of organic matter （31.8%- 48.0%）, total N （16.3-26.4 g kg^-1） and total P （15.1-23.9 g kg^-1）, indicating high potential agricultural benefits of their practical applications. However, total Zn and Ni contents in the sludge exceeded the values permitted in China＇s control standards for pollutants in sludges from agricultural use （GB 4284-1984）. The residual fraction was the predominant fraction for Mo, Ni and Cr, the oxidizable fraction was the primary fraction for Cu and Pb, and the exchangeable and reducible fractions were principal for Zn. The distribution of different chemical fractions among the sludge samples refiected differences in their physicochemical properties, especially pH. The sludge pH was negatively correlated with the percentages of reducible fraction of Cu and exchangeable fraction of Zn. The sludges from these plants might not be suitable for agricultural applications due to their high contents of Zn, Ni and Cr, as well as high potential of mobility and bioavailability of Zn.

关键词： fractions heavy metals sequential extraction sewage sludge

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Osteotomy combined with the trephine technique for invisible implant fracture:A case report

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World Journal of Clinical Cases 2022年第16期10卷 5479-5486页

作者： Liang-Wen Chen min wang hai-Bin Xia Dong Chen Department of Oral Implantology School and Hospital of StomatologyWuhan UniversityWuhan 430079Hubei ProvinceChina

BACKGROUND Implant fracture is one of the most serious mechanical complications of dental *** treatment necessitates visibility of the apical portion of the fractured implant,whereas for deep and invisible implant fractures,the traditional trephine method has been *** removal of the marginal bone to expose the fracture surface would be a time-consuming and extensively damaging ***,we propose a novel technique to address invisible implant *** SUMMARY A 50-year-old woman was referred to our department with the chief complaint that her right mandibular implant tooth had fallen out 3 mo ***-beam computed tomography examination showed an implant fracture with a fracture surface 5.1 mm below the crestal *** patient was treated with osteotomy combined with the trephine technique to expose the surgical field and remove the *** invisible fractured implant was successfully removed,with minimal trauma.A modified Wafer technique-supported guided bone regeneration treatment was then administered to restore the buccal bone wall and preserve the bone *** months later,fine regenerative bone and a wide alveolar crest in the edentulous area were observed,and a new implant was *** months later,restoration was completed using a cemented ceramic *** and radiographic examinations 12 mo after loading fulfilled the success *** patient reported no complaints and was *** Osteotomy combined with the trephine technique can be effectively used to address deep and invisible implant fractures.

关键词： Dental implant Invisible implant fracture Osteotomy Explanation trephine Transformed Wafer technique Case report

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Magneto-Optical Trap of Cesium Atoms

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Chinese Physics Letters 1996年第11期13卷 821-824页

作者： GAN Jian-hua LI Yi-min CHEN Xu-zong LIU hai-feng YANG Dong-hai wang Yi-qiu Department of Electronics Peking UniversityBeijing 100871 Permanent address:Shaanxi Astronomical Observatory Chinese Academy of SciencesLintong 710600

We have trapped a cold sample of cesium atoms in a magneto-optical *** damped harmonic force of magneto-optical trap was used to capture and trap the cesium atoms directly from a room temperature *** 1.5×10^(7) cesium atoms with a density of 3×10^(9) atoms/cm^(3) formed a 4mm^(3) cesium atomic cloud with temperature below 500μK.

关键词： harmonic cesium magneto

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Two bone blocks sandwich technique for horizontal reconstruction of severely atrophic alveolar ridge in anterior maxilla: A case report

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World Journal of Clinical Cases 2020年第5期8卷 971-979页

作者： hai-Bin Xia Yu-Feng Zhang Bin Shi min wang Department of Oral Implantology School and Hospital of StomatologyWuhan UniversityWuhan 430079Hubei ProvinceChina The State Key Laboratory Breeding Base of Basic Science of Stomatology Hubei Province and Key Laboratory of Oral Biomedicine(Wuhan University)Ministry of Education(Hubei-MOST and KLOBM)Wuhan 430079Hubei ProvinceChina

BACKGROUND Severe horizontal bone deficiency of the maxillary anterior region is considered a major challenge in reconstruction and successful implant *** approaches have been developed to augment bone *** these approaches,onlay bone graft,alveolar bone splitting,and guided bone regeneration have been *** SUMMARY A 22-year-old female patient,with no previous medical history,presented to the Department of Oral Implantology,Wuhan University due to a missing right maxillary *** X-ray results showed severe horizontal bone deficiency,with an available bone width of 3.1-4.0 *** two bone blocks sandwich technique was performed to augment the bone *** 6 months healing,X-ray results showed that the newly formed alveolar ridge dimension increased to 4.7-9.5 mm *** insertion surgery was performed and allceramic restorations were *** implant was stable at the 1-year followup visit after restoration,and the X-ray showed a stable bone level around the dental *** scores for the pink esthetic score and white esthetic score were 12 and 8,respectively,and the patient was satisfied with the esthetic *** The two bone blocks sandwich technique may be an alternative treatment option in augmenting severe horizontal bone deficiency of the anterior maxilla.

关键词： Horizontal bone resorption Onlay bone graft Sandwich Dental implant Esthetic Case report

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