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An enamel-inspired bioactive material with multiscale structure and antibacterial adhesion property

Bioactive Materials 2022年第1期7卷 491-503页

作者： Hai Ming Wong yu yuan zhang Quan Li Li Paediatric Dentistry and Orthodontics Faculty of DentistryThe University of Hong Kong34 Hospital RoadHong Kong Collage and Hospital of Stomatology Anhui Medical UniversityNo.69Meishan RoadHeifeiChina

Conventional dental materials lack of the hierarchical architecture of enamel that exhibits excellent intrinsic-extrinsic mechanical properties.Moreover,restorative failures frequently occur due to physical and chemical mismatch between artificial materials and native dental hard tissue followed by recurrent caries which is caused by sugar-fermenting,acidogenic bacteria invasion of the defective cite.In order to resolve the limitations of the conventional dental materials,the aim of this study was to establish a non-cell-based biomimetic strategy to fabricate a novel bioactive material with enamel-like structure and antibacterial adhesion property.The evaporation-based,bottom-up and self-assembly method with layer-by-layer technique were used to form a large-area fluorapatite crystal layer containing antibacterial components.The multilayered structure was constructed by hydrothermal growth of the fluorapatite crystal layer and highly conformal adsorption to the crystal surface of a polyelectrolyte matrix film.Characterization and mechanical assessment demonstrated that the synthesized bioactive material resembled the native enamel in chemical components,mechanical properties and crystallographic structure.Antibacterial and cytocompatibility evaluation demonstrated that this material had the antibacterial adhesion property and biocompatibility.In combination with the molecular dynamics simulations to reveal the effects of variables on the crystallization mechanism,this study brings new prospects for the synthesis of enamel-inspired materials.

关键词： Biomimetic mineralization Enamel-inspired material Bioactive material Graphene oxide Enamel-like structure

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An improved construction algorithm of polar codes based on the frozen bits

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Optoelectronics Letters 2024年第3期20卷 157-162页

作者： yuan Jianguo zhang Fengguo yu Linfeng PANG yu School of Optoelectronic Engineering Chongqing University of Posts and TelecommunicationsChongqing 400065China

In order to improve the problems that the minimum hamming weight(MHW) of the polar codes of the traditional Gaussian approximation(GA) construction is small and its performance is not good enough, an improved channel construction algorithm of polar codes based on frozen bits is proposed by combining the construction of the Reed-Muller(RM) code to effectively increase the MHW and analyzing the correcting and checking functions of the frozen bits in the successive cancellation list(SCL) decoding.

关键词： polar algorithm successive

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Application of system identification in a practical active noise control system

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Control Theory and Technology 2024年第2期22卷 282-291页

作者： yu yuan Zhaoyang Sun Hongwei zhang School of Mechanical Engineering Xihua UniversityChengdu610039SichuanChina School of Electrical Engineering Southwest Jiaotong UniversityChengdu611756SichuanChina School of Mechanical Engineering and Automation Harbin Institute of TechnologyShenzhen518055GuangdongChina

Noise pollution has become increasingly severe around the world due to fast urbanization. How to soundproof windows from outside noise is of significant interest for both academia and industry. This paper reports an experimental implementation of normalized minmax active noise control (ANC) algorithm on an open window system, where identifying the model of acoustic sound paths plays a central role. By doing this, traffic noise is attenuated by the ANC system, leading to a relatively quiet indoor environment, while the natural lighting and ventilation functions of a window are remained. Our experiments show that an average of 19 dB(A) noise reduction is achieved.

关键词： Active noise control Multi-input-multi-output system Normalized minimax algorithm System identification

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Numerical simulation of transient characteristics in a bulb turbine during the load rejection process

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Journal of Hydrodynamics 2024年第1期36卷 170-183页

作者： yue Lu yu-quan zhang Zhong-wei He yuan Zheng College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing210098China College of Energy and Electrical Engineering Hohai UniversityNanjing210098China Huadong Engineering Corporation Ltd. Hangzhou311122China

To evaluate the safety of the bulb tubular turbine,the dynamic hydraulic characteristics of a hydropower station system during the load rejection process are studied through numerical simulations and a prototype test.In the developed model,a dynamic grid technology(DGT)controls the closure of the guide vane and the blade,whilst the moment balance equation and the user-defined function(UDF)provide the runner’s rotation speed.The 3-D transient simulation method can well predict the rotation speed and mass flow curves in the state of load rejection.The simulation outcomes of the system performance are basically consistent with the measurement data of the prototype.As observed,the runner is subjected to the reversely increased torque and axial force,the system is in a braking phase,and the maximum speed peaks at 144.6%of the rated speed.Moreover,the internal flow of the runner is greatly affected by the closure of the guide vane,and the draft tube forms an eccentric spiral vortex rope.It breaks downstream,aggravating the instability of the draft tube.Overall,the transient characteristics span for the first five seconds,demonstrating the importance of establishing an efficient governing controller.The obtained results are useful for designing the turbine’s flow channel with a double regulating function and comprehending the turbine’s transient characteristics.

关键词： Bulb tubular turbine load rejection numerical simulation dynamic grid prototype test

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Full-parameter omnidirectional transformation optical devices

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National Science Review 2024年第3期11卷 92-99页

作者： yuan Gao yu Luo Jingjing zhang Zhengjie Huang Bin Zheng Hongsheng Chen Dexin Ye Interdisciplinary Center for Quantum Information State Key Laboratory of Extreme Photonics and InstrumentationZJU-Hangzhou Global Scientific and Technological Innovation CenterZhejiang University School of Electrical and Electronic Engineering Nanyang Technological University CNRS-InternationalNTU-Thales Research Alliance Nanyang Technological University Institute of Electromagnetic Space Southeast University State Key Laboratory of Millimeter Waves Southeast University International Joint Innovation Center The Electromagnetics Academy at Zhejiang University Zhejiang University Key Laboratory of Advanced Micro/Nano Electronic Devices&Smart Systems of Zhejiang Jinhua Institute of Zhejiang UniversityZhejiang University Shaoxing Institute of Zhejiang University Zhejiang University

Transformation optics(TO) provides an unprecedented technique to control electromagnetic(EM) waves by engineering the constitutive parameters of the surrounding medium through a proper spatial transformation. In general, ideal transformation optical devices require simultaneous electric and magnetic responses along all three dimensions. To ease the practical implementation, previous studies usually made use of reduced parameters or other simplified approaches, which inevitably introduce extra reflection or unwanted phase shift. Up to today, experimental realizations of full-parameter transformation optical devices in free space are still quite limited. Here, a general design strategy is proposed to solve this problem.As a specific example, a full-parameter spatial-compression TO medium with constitutive parameters taking the diagonal form diag(a, a, 1/a) for the TM wave incidence was designed and realized experimentally. Such spatial-compression TO media were then applied to the implementation of an ideal omnidirectional invisibility cloak capable of concealing a large-scale object over a wide range of illumination angles. Both the simulation and experiment confirm that the cloak allows for nearly unity transmission of EM waves in the forward direction without introducing extra scattering or phase shift. This work constitutes an important stepping stone for future practical implementation of arbitrary full-parameter omnidirectional transformation optical devices.

关键词： transformation optical devices omnidirectional impedance matching full-parameter invisibility cloak

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CS-FSCL decoding algorithm of polar codes based on critical sets

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Optoelectronics Letters 2024年第7期20卷 418-423页

作者： yuan Jianguo zhang Fengguo HE Jingjie PANG yu School of Optoelectronic Engineering Chongqing University of Posts and Telecommunications

In order to reduce the number of redundant candidate codewords generated by the fast successive cancellation list(FSCL) decoding algorithm for polar codes, a simplified FSCL decoding algorithm based on critical sets(CS-FSCL) of polar codes is proposed. The algorithm utilizes the number of information bits belonging to the CS in the special nodes, such as Rate-1 node, repetition(REP) node and single-parity-check(SPC) node, to constrain the number of the path splitting and avoid the generation of unnecessary candidate codewords, and thus the latency and computational complexity are reduced. Besides, the algorithm only flips the bits corresponding to the smaller log-likelihood ratio(LLR) values to generate the sub-maximum likelihood(sub-ML) decoding codewords and ensure the decoding performance. Simulation results show that for polar codes with the code length of 1 024, the code rates of 1/4, 1/2 and 3/4, the proposed CS-FSCL algorithm, compared with the conventional FSCL decoding algorithm, can achieve the same decoding performance, but reduce the latency and computational complexity at different list sizes. Specifically, under the list size of L=8, the code rates of R=1/2 and R=1/4, the latency is reduced by 33% and 13% and the computational complexity is reduced by 55% and 50%, respectively.

关键词： A

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Ultrasound-guided paravertebral nerve block anesthesia for percutaneous endoscopic laser unroofing treatment of symptomatic simple renal cysts—An innovative ambulatory surgery mode

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Asian Journal of Urology 2024年第1期11卷 65-71页

作者： Jia Hu yuan zhang Yong Liu Xiao yu Shaogang Wang Department of Urology Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina Department of Anesthesiology Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina

Objective:This study was designed to evaluate the feasibility,efficacy,and safety of percutaneous ureteroscopy laser unroofing as an ambulatory surgery for symptomatic simple renal cysts under multilevel paravertebral nerve block anesthesia.Methods:From December 2015 to September 2017,33 simple renal cyst patients who had surgical indications were enrolled.Under ultrasound guidance,the T10/T11,T11/T12,and T12/L1 paravertebral spaces were identified,and 7-10 mL 0.5%ropivacaine was injected at each segment.Then a puncture needle was placed inside the cyst cavity under ultrasonic monitoring.A guidewire was introduced followed by sequential dilation up to 28/30 Fr.The extra parenchymal portion of the cyst wall was dissociated and incised using a thulium laser,and a pathological examination was performed.Results:Sensory loss to pinprick from T8 to L1 and sensory loss to ice from T6 to L2 were observed in all patients.None of the patients complained of pain during surgery.No serious complications occurred perioperatively.After the surgery,all patients recovered their lower limb muscle strength quickly,got out of bed,resumed oral feeding,and left the hospital within 24 h of admission.The pathologic diagnosis of all cyst walls was a simple renal cyst.The mean follow-up was 35.8 months.At the end of follow-up,the cyst units were reduced in size by more than 50%compared to the preoperative size,and no patient experienced a recurrence.Conclusion:Multi-level paravertebral nerve block for percutaneous ureteroscopy laser unroofing as an ambulatory surgery mode is feasible,safe,and effective for the treatment of simple renal cysts in selected patients.

关键词： Paravertebralnerve blockanesthesia Percutaneous puncture Simplerenalcyst Unroofing Ambulatorysurgery

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Optimal geometrical configuration and oxidation state of cobalt cations in spinel oxides to promote the performance of Li-O_(2) battery

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Nano Research 2024年第1期17卷 221-227页

作者： yu zhang Shuting zhang Mengwei yuan yufeng Li Rong Liu Caiyun Nan Chen Chen Engineering Research Center of Advanced Rare Earth Materials Department of ChemistryTsinghua UniversityBeijing 100084China Beijing Key Laboratory of Energy Conversion and Storage Materials Institution College of ChemistryBeijing Normal UniversityBeijing 100875China X-ray diffraction Lab Analytical and Testing CenterBeijing Normal UniversityBeijing 100875China

Co_(3)O_(4) is considered as one of promising cathode catalysts for lithium oxygen(Li-O_(2))batteries,which contains both tetrahedral Co^(2+)sites(Co^(2+)Td)and octahedral Co^(3+)sites(Co^(3+)Oh).It is important to reveal the effect of optimal geometric configuration and oxidation state of cobalt ion in Co_(3)O_(4) to improve the performance of Li-O_(2) batteries.Herein,through regulating the synthesis process,Co^(2+)and Co^(3+)sites in Co_(3)O_(4) were replaced with Zn and Al atoms to form materials with a unique Co site.The Li-O_(2) batteries based on ZnCo_(2)O_(4) showed longer cycle life than that of CoAl_(2)O_(4),suggesting that in Co_(3)O_(4),the Co^(3+)Oh site is a relatively better geometric configuration than Co^(2+)Td site for Li-O_(2) batteries.Theoretical calculations revealed that Co^(3+)Oh sites provide higher catalysis activity,regulating the adsorption energy of the intermediate LiO_(2) and accelerating the kinetics of the reaction in batteries,which further leads to the change of the morphology of the discharge product and ultimately improves the electrochemical performance of the batteries.

关键词： lithium oxygen(Li-O_(2))batteries geometrical configuration oxidation state lithium peroxide

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Unveiling the Contribution of Lactic Acid to the Passivation Behavior of Ti-6Al-4V Fabricated by Laser Powder Bed Fusion in Hank’s Solution

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 102-118页

作者： yu-Hang Chu Liang-yu Chen Bo-yuan Qin Wenbin Gao Fanmin Shang Hong-yu Yang Lina zhang Peng Qin Lai-Chang zhang School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang212100China Foshan(Southern China)Institute for New Materials Foshan528200China Key Laboratory of Automobile Materials Ministry of Education and Department of Materials Science and EngineeringJilin UniversityChangchun130025China Centre for Advanced Materials and Manufacturing School of EngineeringEdith Cowan University270 Joondalup DriveJoondalupPerthWA6027Australia

In actual physiological environments,bacteria can activate the immune system and release lactic acid.However,the detailed contribution of lactic acid to the passivation behavior of titanium(Ti)alloys is still unclear.The current work investigated the in vitro passivation behavior of Ti-6Al-4V(TC4)alloys fabricated by laser powder bed fusion in Hank's solution with and without adding lactic acid.Electrochemical methods,inductively coupled plasma atomic emission spectrometer,and X-ray photoelectron spectroscopy were jointly used.Adding lactic acid decreases the corrosion resistance of samples by degrading the formed passive film.The film formed in the(lactic acid)-containing solution exhibits a higher level of oxygen vacancies and a lower thickness,attributed to the suppressed formation of Ti^(4+)transformed from Ti^(3+)and Ti^(2+).Moreover,the presence of lactic acid would increase the open circuit potential,relieve the ions release,and hinder the deposition of calcium phosphates within 24 h immersion.

关键词： Titanium alloy Corrosion behavior Passive film Lactic acid Laser powder bed fusion

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Robust cooperative multi-agent reinforcement learning via multi-view message certification

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Science China(Information Sciences) 2024年第4期67卷 131-145页

作者： Lei yuan Tao JIANG Lihe LI Feng CHEN Zongzhang zhang Yang yu National Key Laboratory for Novel Software Technology Nanjing University Polixir Technologies

Many multi-agent scenarios require message sharing among agents to promote coordination,hastening the robustness of multi-agent communication when policies are deployed in a message perturbation environment. Major relevant studies tackle this issue under specific assumptions, like a limited number of message channels would sustain perturbations, limiting the efficiency in complex scenarios. In this paper,we take a further step in addressing this issue by learning a robust cooperative multi-agent reinforcement learning via multi-view message certification, dubbed CroMAC. Agents trained under CroMAC can obtain guaranteed lower bounds on state-action values to identify and choose the optimal action under a worst-case deviation when the received messages are perturbed. Concretely, we first model multi-agent communication as a multi-view problem, where every message stands for a view of the state. Then we extract a certificated joint message representation by a multi-view variational autoencoder(MVAE) that uses a product-of-experts inference network. For the optimization phase, we do perturbations in the latent space of the state for a certificate guarantee. Then the learned joint message representation is used to approximate the certificated state representation during training. Extensive experiments in several cooperative multi-agent benchmarks validate the effectiveness of the proposed CroMAC.

关键词： multi-agent reinforcement learning robust communication adversarial training multi-view learning message certification

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