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Exponentially increased nucleation ability for poly(L-lactide) by adding acid-oxidized multiwalled carbon nanotubes with reduced aspect ratios

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Science China Chemistry 2013年第2期56卷 181-194页

作者： ZHONG Yong ZHANG YaQiong YANG JingJing LI WenLin WANG ZhiGang XU DongHua CHEN ShouYu ding yunsheng CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and Engineering Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences Institute of Polymer Materials & Chemical Engineering School of Chemical Engineering Hefei University of Technology Anhui Key Laboratory of Controllable Chemistry Reaction & Material Chemical Engineering

Acid-oxidized multiwalled carbon nanotubes (A-MWCNTs) with a range of reduced aspect ratios (from about 11 to 5.8) were obtained by acid oxidization of MWCNTs in the mixture of HNO 3 and H 2 SO 4 for varying periods of 1, 3, 8 and 12 h, respec- tively. The aspect ratios and surface functionalization of A-MWCNTs were well characterized by scanning electron microsco- py (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and thermogravimetric analysis (TGA). Poly(L-lactide)/A-MWCNT composites containing 0.5 wt% A-MWCNTs with a range of reduced aspect ratios were prepared by solution cast. The effects of added A-MWCNTs on the isothermal crystallization kinetics of poly(L-lactide)/A-MWCNT composites were investigated by means of differential scanning calorimetry (DSC), rheology and polarized optical microscopy (POM). It is surprising to find that not only the addition of A-MWCNTs effectively increases the poly(L-lactide) (PLA) crys- tallization kinetics, but also the nucleation ability of A-MWCNTs for PLA crystallization exponentially increases with the re- duced aspect ratio, that is to say, those with lower aspect ratios show much stronger nucleation ability for PLA crystallization than those with higher aspect ratios. The exponentially increased nucleation ability of A-MWCNTs with a range of reduced aspect ratios for PLA crystallization is disclosed.

关键词：多壁碳纳米管 L-丙交酯核能力长宽比倍增氧化等温结晶动力学傅立叶变换红外光谱

2016-2022年安徽省结核病耐药监测结果分析

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中国防痨杂志 2024年第5期46卷 531-537页

作者：包训迪梁锁李军叶倩吴丹丹王舒李跃丁运生刘洁安徽省胸科医院(省结核病防治研究所) 合肥230022

目的:分析2016—2022年安徽省4个国家级结核病耐药监测点分离的结核分枝杆菌的耐药谱变化趋势,从而掌握安徽省结核病和耐药结核病的流行和防控效果。方法:连续纳入2016—2022年4个耐药监测点的病原学阳性肺结核患者3073例,采集患者的基... 详细信息

目的:分析2016—2022年安徽省4个国家级结核病耐药监测点分离的结核分枝杆菌的耐药谱变化趋势,从而掌握安徽省结核病和耐药结核病的流行和防控效果。方法:连续纳入2016—2022年4个耐药监测点的病原学阳性肺结核患者3073例,采集患者的基本信息并收集痰标本进行分离培养,培阳菌株进行菌种鉴定,共获得结核分枝杆菌2336株,采用比例法对结核分枝杆菌开展6种抗结核药物[异烟肼(INH)、利福平(RFP)、链霉素(Sm)、乙胺丁醇(EMB)、氧氟沙星(Ofx)和卡那霉素(Km)]的药物敏感性试验。结果:2336株结核分枝杆菌菌株中,有1893株(81.04%)对6种抗结核药物全部敏感,443株对至少1种或更多抗结核药物耐药,耐药率为18.96%(443/2336),其中初治为16.80%(348/2071),复治为35.85%(95/265),耐多药菌株98株(4.20%)。在6种抗结核药物中,抗结核药物单耐药率由高到低分别为:INH(10.55%,236/2336)、Sm(8.18%,183/2336)、Ofx(6.53%,146/2336)、RFP(5.95%,133/2336)、EMB(2.37%,53/2336)、Km(1.97%,44/2336)。2016—2022年,抗结核药物Ofx、INH、EMB和Km耐药率[2016年分别为10.49%(30/286)、12.24%(35/286)、1.75%(5/286)、2.45%(7/286),2022年分别为3.89%(18/463)、9.29%(43/463)、0.86%(4/463)、1.08%(5/463)]呈下降趋势(χ^(2)_(趋势)值分别为16.964、15.989、15.798、26.075,P值均<0.05),初治患者的耐药率和多耐药率[2016年分别为22.76%(56/246)、6.50%(16/246),2022年分别为14.15%(60/424)、1.89%(8/424)]也呈下降趋势(χ^(2)_(趋势)值分别为14.445、16.688,P值均<0.05);在不同年龄段中,40~59岁年龄段结核分枝杆菌菌株的耐药率(22.74%,146/642)最高。结论:安徽省结核病的耐药形势依然严峻,复治患者、40~59岁人群和城镇地区患者结核病耐药问题需要重点关注。

关键词：分枝杆菌,结核抗药性,细菌人群监测

Interface Engineered Microcellular Magnetic Conductive Polyurethane Nanocomposite Foams for Electromagnetic Interference Shielding

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Nano-Micro Letters 2021年第10期13卷 131-146页

作者： Guolong Sang Pei Xu Tong Yan Vignesh Murugadoss Nithesh Naik yunsheng ding Zhanhu Guo Department of Polymer Science and Engineering School of Chemistry and Chemical Engineeringand Anhui Key Laboratory of Advanced Functional Materials and DevicesHefei University of TechnologyHefei 230009People’s Republic of China Advanced Materials Division Engineered Multifunctional Composites(EMC)Nanotech.LLCKnoxvilleTN 37934USA Integrated Composites Laboratory(ICL) Department of Chemical and Biomolecular EngineeringUniversity of TennesseeKnoxvilleTN 37996USA Department of Mechanical and Manufacturing Engineering Manipal Institute of TechnologyManipal Academy of Higher EducationManipalKarnataka 576104India

Lightweight microcellular polyurethane(TPU)/carbon nanotubes(CNTs)/nickel-coated CNTs(Ni@CNTs)/polymerizable ionic liquid copolymer(PIL)composite foams are prepared by non-solvent induced phase separation(NIPS).CNTs and Ni@CNTs modified by PIL provide more heterogeneous nucleation sites and inhibit the aggregation and combination of microcellular structure.Compared with TPU/CNTs,the TPU/CNTs/PIL and TPU/CNTs/Ni@CNTs/PIL composite foams with smaller microcellular structures have a high electromagnetic interference shielding effectiveness(EMI SE).The evaporate time regulates the microcellular structure,improves the conductive network of composite foams and reduces the microcellular size,which strengthens the multiple reflections of electromagnetic wave.The TPU/10CNTs/10Ni@CNTs/PIL foam exhibits slightly higher SE values(69.9 dB)compared with TPU/20CNTs/PIL foam(53.3 dB).The highest specific EMI SE of TPU/20CNTs/PIL and TPU/10CNTs/10Ni@CNTs/PIL reaches up to 187.2 and 211.5 dB/(g cm^(−3)),respectively.The polarization losses caused by interfacial polarization between TPU substrates and conductive fillers,conduction loss caused by conductive network of fillers and magnetic loss caused by Ni@CNT synergistically attenuate the microwave energy.

关键词： Polyurethane Nanocomposites Microcellular Electromagnetic interference shielding

Wide tunable laser based on electrically regulated bandwidth broadening in polymer-stabilized cholesteric liquid crystal

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Photonics Research 2019年第2期7卷 137-143页

作者： HONGBO LU CHENG WEI QIANG ZHANG MIAO XU yunsheng ding GUOBING ZHANG JUN ZHU KANG XIE XIAOJUAN ZHANG ZHIJIA HU LONGZHEN QIU Key Laboratory of Special Display Technology National Engineering Laboratory of Special Display TechnologyState Key Laboratory of Advanced Display TechnologyAcademy of Opto-Electronic TechnologyHefei University of Technology Key Laboratory of Advanced Functional Materials and Devices Anhui ProvinceSchool of Chemistry and Chemical EngineeringHefei University of Technology School of Instrument Science and Opto-Electronics Engineering Hefei University of Technology Aston Institute of Photonic Technologies Aston University State Key Laboratory of Environment-Friendly Energy Materials Southwest University of Science and Technology

Electrically responsive photonic crystals represent one of the most promising intelligent material candidates for technological applications in optoelectronics. In this research, dye-doped polymer-stabilized cholesteric liquid crystals(PSCLCs) with negative dielectric anisotropy were fabricated, and mirrorless lasing with an electrically tunable wavelength was successfully achieved. Unlike conventional liquid-crystal lasers, the proposed laser aided in tuning the emission wavelength through controlling the reflection bandwidth based on gradient pitch distribution. The principal advantage of the electrically controlled dye-doped PSCLC laser is that the electric field is applied parallel to the helical axis, which changes the pitch gradient instead of rotating the helix axis, thus keeping the heliconical structure intact during lasing. The broad tuning range(～110 nm) of PSCLC lasers,coupled with their stable emission performance, continuous tunability, and easy fabrication, leads to its numerous potential applications in intelligent optoelectronic devices, such as sensing, medicine, and display.

关键词： Wide tunable laser electrically polymer-stabilized

Whittle’s Index Based Sensor Scheduling for Multiprocess Systems Under DoS Attacks

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Journal of Systems Science & Complexity 2024年第1期37卷 329-350页

作者： CAI Zai ding Kemi Shenzhen Key Laboratory of Control Theory and Intelligent Systems Southern University of Science and TechnologyShenzhen 518055China.

In this paper,the authors consider how to design defensive countermeasures against DoS attacks for remote state estimation of multiprocess systems.For each system,a sensor will measure its state and transmits the data packets through an unreliable channel which is vulnerable to be jammed by an attacker.Under limited communication bandwidth,only a subset of sensors are allowed for data transmission,and how to select the optimal one to maximize the accuracy of remote state estimation is the focus of the proposed work.The authors first formulate this problem as a Markov decision process and investigate the existence of optimal policy.Moreover,the authors demonstrate the piecewise monotonicity structure of optimal policy.Given the difficulty of obtaining an optimal policy of large-scale problems,the authors develop a suboptimal heuristic policy based on the aforementioned policy structure and Whittle’s index.Moreover,a closed form of the indices is derived in order to reduce implementation complexity of proposed scheduling policy and numerical examples are provided to illustrate the proposed developed results.

关键词： DoS attacks Kalman filter remote state estimation Whittle’s index.

Constraint on the focal mechanism of the 2011 Tohoku earthquake from the radial modes

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Geodesy and Geodynamics 2024年第1期15卷 27-32页

作者： Weikun Chen Hao ding School of Geodesy and Geomatics Hubei LuoJia LaboratoryWuhan UniversityWuhan 430079China

Different from other normal modes of the Earth’s free oscillation that depend on all the six components(M_(rr),M_(tt),M_(pp),M_(rt),M_(rp),and M_(tp))of the centroid moment tensor,the amplitudes of the radial modes depend on the M_(rr)component(e.g.,scalar moment(M_(0)),dip(δ),and slip(λ))and hypocenter depth of the focal mechanism,and hence can be easily used to constrain these parameters of the focal mechanism.In this study,we use the superconducting gravimeter(SG)records after the 2011 Tohoku earthquake to analyze the radial modes_(0)S_(0)and_(1)S_(0).Based on the solutions of the focal mechanism provided by the GCMT and USGS,we can obtain the theoretical amplitudes of these two radial modes.Comparing the theoretical amplitudes with the observation amplitudes,it is found that there are obvious differences between the former and the latter,which means that the GCMT and USGS focal mechanisms cannot well represent the real focal mechanism of the 2011 event.Taking the GCMT solution as a reference and changing the depth and the three parameters of the M_(rr)moment,the scalar moment(M_(0))and the dip(δ)have significant influences,but the effects of the slip(λ)and the depth are minor.After comparisons,we provide a new constraint(M_(0)=5.8±0.09×10^(22)N·m,δ=10.1±0.08°,λ=88°,and depth=20 km)for the focal mechanism of the 2011 event.In addition,we further determine the center frequency(1.631567±2.6e^(-6)mHz)and quality factor(2046.4±50.1)of the_(1)S_(0)mode.

关键词： Focal mechanism Radial modes Gravity observation

Catalysis by subsurface metal atoms in Al(001) through electron transfer

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National Science Review 2024年第4期11卷 12-13页

作者： Bo Sun ding Ma Beijing National Laboratory for Molecular Science New Cornerstone Science Laboratory College of Chemistry and Molecular Engineering Peking University

Heterogeneous catalysis plays a crucial role in the chemical industry, which has evolved from the investigation of chemisorption to an electronic structure[1]. Diverse strategies, such as alloying,doping, and confining, have been applied to enhance the catalytic properties of active sites through electronic modulation. The electron transfer between active sites and substrates profoundly influences catalytic activity [2].

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A vertical track nonlinear energy sink

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 931-946页

作者： Meng LI Hu ding Shanghai Key Laboratory of Mechanics in Energy Engineering School of Mechanics and Engineering ScienceShanghai Frontier Science Center of MechanoinformaticsShanghai UniversityShanghai 200444China

Eliminating the effects of gravity and designing nonlinear energy sinks(NESs)that suppress vibration in the vertical direction is a challenging task with numerous damping requirements.In this paper,the dynamic design of a vertical track nonlinear energy sink(VTNES)with zero linear stiffness in the vertical direction is proposed and realized for the first time.The motion differential equations of the VTNES coupled with a linear oscillator(LO)are established.With the strong nonlinearity considered of the VTNES,the steady-state response of the system is analyzed with the harmonic balance method(HBM),and the accuracy of the HBM is verified numerically.On this basis,the VTNES prototype is manufactured,and its nonlinear stiffness is identified.The damping effect and dynamic characteristics of the VTNES are studied theoretically and experimentally.The results show that the VTNES has better damping effects when strong modulation responses(SMRs)occur.Moreover,even for small-amplitude vibration,the VTNES also has a good vibration suppression effect.To sum up,in order to suppress the vertical vibration,an NES is designed and developed,which can suppress the vertical vibration within certain ranges of the resonance frequency and the vibration intensity.

关键词： track nonlinear energy sink(TNES) vertical direction gravity nonlinear stiffness harmonic balance method(HBM) vibration control

Deep structure of the Southeast Asian curved subduction system and its dynamic process

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Journal of Oceanology and Limnology 2024年第3期42卷 701-704页

作者： Weiwei ding Key Laboratory of Submarine Geoscience&Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China School of Oceanography Shanghai Jiao Tong UniversityShanghai 200030China

The deep structure,material circulation,and dynamic processes in the Southeast Asia have long been an elusive scientific puzzle due to the lack of systematic scientific observations and recognized theoretical models.Based on the deep seismic tomography using long-period natural earthquake data,in this study,the deep structure and material circulation of the curved subduction system in Southeast Asia was studied,and the dynamic processes since 100 million years ago was reconstructed.It is pointed out that challenges still exist in the precise reconstruction of deep mantle structures of the study area,the influence of multi-stage subduction on deep material exchange and shallow magma activity,as well as the spatiotemporal evolution and coupling mechanism of multi-plate convergence.Future work should focus on high-resolution land-sea joint 3-D seismic tomography imaging of the curved subduction system in the Southeast Asia,combined with geochemical analysis and geodynamic modelling works.

关键词： curved subduction system deep structure material recycling dynamic process Southeast Asia