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The bright Single Pulse Emission from PSR b1133+16

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Research in Astronomy and Astrophysics 2024年第4期24卷 253-261页

作者： Jun Tan Zhi-Gang Wen Zhen wang Xue-Feng Duan Hong-Guang wang Na wang Vishal Gajjar Jian-Ping yuan Rai yuen Wen-Ming yan Jian-Ling Chen Wei Han Hui wang Cheng-bing Lyu Ai-Jun Dong Maths and Information Technology School Yuncheng UniversityYuncheng 044000China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China Xinjiang Key Laboratory of Radio Astrophysics Urumqi 830011China School of Physics and Materials Science Guangzhou UniversityGuangzhou 510006China Space Science Laboratory University of CaliforniaBerkeley 94710USA Department of Physics and Electronic Engineering Yuncheng UniversityYuncheng 044000China School of Physics and Electronic Science Guizhou Normal UniversityGuiyang 550025China

We have conducted a comprehensive investigation into the bright single pulse emission from PSR b1133+16using the Giant Metrewave Radio *** time resolution data(61μs)were obtained at a center frequency of 322 MHz with a bandwidth of 32 MHz over a continuous observation period of 7.45 hr.A total of 1082 bright pulses were sporadically detected with peak flux densities ranging from 10 to 23 times stronger than the average pulse ***,no giant pulse-like emission with a relative pulse energy larger than 10 and extremely short duration was detected,indicating that these bright pulses cannot be categorized as giant pulse *** majority of these bright pulses are concentrated in pulse phases at both the leading and trailing windows of the average pulse profile,with an occurrence ratio of approximately *** pulse energy distribution for all individual pulses can be described by a combination of two Gaussian components and a cutoff power-law with an index of α=-*** updated nulling fraction of 15.35%±0.45% was determined from the energy *** emission of individual pulses follows a log-normal distribution in peak flux density *** is imperative that regular phase drifting in bright pulse sequence is identified in both the leading and trailing components for the first *** physical mechanisms are discussed in detail to provide insights into these observations.

关键词： (stars:)pulsars:general (stars:)pulsars:individual(PSR b1133+16) methods:observational methods:data analysis

Microstructure and Internal Friction behavior of Laser 3D Printed Fe-based Amorphous Composites

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 196-204页

作者： Shuilong Huang Qingjun Chen Li Ji Kan wang Guosheng Huang School of Material Science and Engineering Nanchang Hangkong UniversityNanchang330063China State Key Laboratory for Marine Corrosion and Protection Luoyang Ship Material Research Institute(LSMRI)Qingdao266237China

Laser 3D printing,also known as laser additive manufacturing(LAM),is favored for its ability to form bulk metallic glass(bMG)and its composite materials(bMGcs)with freeform *** this work,two different kinds of Fe_(41)Co_(7)Cr_(15)Mo_(14)C_(15)b_(6)y_(2)amorphous coatings(A and b)were prepared by using LAM technology under air-and water-cooled conditions,respectively;meanwhile,to reduce the cracks generated due to the residual thermal stresses,coating C obtained by air-sweep annealing of b with a low energy-density *** morphology and amorphous content and microstructure of the coatings were investigated,the results show many cracks in coating b deposited under water-cooled conditions,and its microstructure shows an amorphous-crystal-nanocrystalline mixed *** was suppressed in coating C,obtained by air-sweep annealing based on coating b,but the amorphous content was reduced from 32.6 to 13.4%.And the hardness and corrosion resistance of the coating will increase with the increase in the amorphous ***,the internal friction behavior of a bMGcs was prepared on the basis of the process of sample C is compared with that of as-cast amorphous *** results show that the low temperature internal friction behavior of bMGcs is affected by the defects produced during printing,and the high temperature internal friction behavior is affected by the precipitated hard phase.

关键词： Laser 3D printing Amorphous coating Microstructure Corrosion resistance Internal friction behavior

Repeatability and reproducibility of corneal higher-order aberrations measurements after small incision lenticule extraction using the Scheimpfug-Placido topographer

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Eye and Vision 2024年第1期10卷 1-9页

作者： Rui Ning Rongrong Gao David PPiñero Jun Zhang Qingyi Gao yili Jin yiran wang Chenxiao wang Jinhai Huang Eye Hospital and School of Ophthalmology and Optometry Wenzhou Medical UniversityWenzhouZhejiangChina Eye Institute and Department of Ophthalmology Eye and ENT HospitalFudan UniversityShanghaiChina Group of Optics and Visual Perception Department of OpticsPharmacology and AnatomyUniversity of AlicanteAlicanteSpain NHC Key Laboratory of Myopia(Fudan University) Key Laboratory of MyopiaChinese Academy of Medical SciencesShanghaiChina Shanghai Research Center of Ophthalmology and Optometry ShanghaiChina

background:To evaluate the precision of corneal higher-order aberrations measurements after small incision lenticule extraction(SMILE)using the Sirius Scheimpfug-Placido topographer(CSO,Italy).Methods:Seventy-fve eyes from 75 postoperative subjects were included in this prospective *** consecutive corneal aberrometric measurements were obtained with the Scheimpfug-Placido topographer by two experienced operators to assess intra-and inter-observer *** within-subject standard deviation(Sw),test-retest repeatability(TRT)and the intraclass correlation coefcient(ICC)were ***:For intraobserver repeatability of anterior and total corneal aberrations,all ICCs were more than 0.922,except for trefoil(0.722 to 0.768).The ICCs of total root mean square(RMS),coma Z(3,±1),and spherical aberration Z(4,0)were over 0.810 while higher-order RMS,trefoil Z(3,±3),and astigmatism II Z(4,±2)were below 0.634 for posterior corneal surface *** Sw values for all types of aberrations were equal to or below 0.07μ*** interobserver reproducibility,all TRT values were no more than 0.12μm,0.05μm,and 0.11μm for anterior,posterior,and total corneal aberrations,*** ICC values ranged from 0.875 to 0.989,from 0.686 to 0.976 and over 0.834 for anterior,posterior,and total corneal aberrations,***:The repeatability of measurements of anterior and total corneal aberrations with the Sirius system in corneas after SMILE surgery was high,except for *** was some variability in posterior corneal aberrometric *** reproducibility of corneal aberrometric measurements was observed between measurements of both examiners,except for trefoil,with poor to moderate reproducibility.

关键词： Sirius Higher-order aberrations Repeatability Reproducibility Small incision lenticule extraction

A particle-resolved heat-particle-fluid coupling model by DEM-IMb-LbM

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2267-2281页

作者： Ming Xia Jinlong Fu y.T.Feng Fengqiang Gong Jin yu Hunan Key Laboratory of Geomechanics and Engineering Safety Xiangtan UniversityXiangtan411105China Zienkiewicz Institute for Modelling Data and AISwansea UniversitySwanseaSA18EPUK School of Civil Engineering Southeast UniversityNanjing211189China Fujian Research Center for Tunneling and Urban Underground Space Engineering Huaqiao UniversityXiamen361021China

Multifield coupling is frequently encountered and also an active area of research in geotechnical *** this work,a particle-resolved direct numerical simulation(PR-DNS)technique is extended to simulate particle-fluid interaction problems involving heat transfer at the grain *** this extended technique,an immersed moving boundary(IMb)scheme is used to couple the discrete element method(DEM)and lattice boltzmann method(LbM),while a recently proposed Dirichlet-type thermal boundary condition is also adapted to account for heat transfer between fluid phase and solid *** resulting DEM-IbM-LbM model is robust to simulate moving curved boundaries with constant temperature in thermal *** facilitate the understanding and implementation of this coupled model for non-isothermal problems,a complete list is given for the conversion of relevant physical variables to lattice ***,benchmark tests,including a single-particle sedimentation and a two-particle drafting-kissing-tumbling(DKT)simulation with heat transfer,are carried out to validate the accuracy of our coupled *** further investigate the role of heat transfer in particle-laden flows,two multiple-particle problems with heat transfer are *** examples demonstrate that the proposed coupling model is a promising high-resolution approach for simulating the heat-particle-fluid coupling at the grain level.

关键词： Particle-fluid interaction Heat transfer Discrete element method(DEM) Lattice boltzmann method(LbM) Dirichlet-type thermal boundary Direct numerical simulation

A multi-functional MgF_(2)/polydopamine/hyaluronan-astaxanthin coating on the biodegradable ZE21b alloy with better corrosion resistance and biocompatibility for cardiovascular application

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Journal of Magnesium and Alloys 2024年第3期12卷 1102-1116页

作者： yachen Hou Xueqi Zhang Jingan Li Liguo wang Shaokang Guan School of Materials Science and Engineering and Henan Key Laboratory of Advanced Magnesium Alloy and Key Laboratory of Materials Processing and Mold Technology(Ministry of Education) Zhengzhou UniversityZhengzhou 450001China

The cardiovascular diseases(CVD)continue to be the major threat to global public health over the years,while one of the effective methods to treat CVD is stent *** magnesium(Mg)alloys have great potential applications in cardiovascular stents benefit from their excellent biodegradability and ***,excessive degradation rate and the delayed surface endothelialization still limit their further *** this study,we modified a Mg-Zn-y-Nd alloy(ZE21b)by preparing MgF_(2) as the corrosion resistance layer,the dopamine polymer film(PDA)as the bonding layer,and hyaluronic acid(HA)loaded astaxanthin(ASTA)as an important layer to directing the cardiovascular cells *** electrochemical test results showed that the MgF_(2)/PDA/HA-ASTA coating improved the corrosion resistance of *** cytocompatibility experiments also demonstrated that this novel composite coating also selectively promoted endothelial cells proliferation,inhibited hyperproliferation of smooth muscle cells and adhesion of *** with the HAloaded rapamycin(RAPA)coating,our MgF_(2)/PDA/HA-ASTA coating showed better blood compatibility and cytocompatibility,indicating stronger multi-functions for the ZE21b alloy on cardiovascular application.

关键词： biodegradable ZE21b alloy Reendothelialization Surface modification Hyaluronic acid Astaxanthin.

Polyolefin vitrimers bearing acetoacetate functionality

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Science China Chemistry 2024年第11期67卷 3861-3867页

作者： Zihao wang yue Liu Wenmin Pang Ao Chen Min Chen Chinese Academy of Sciences (CAS) Key Laboratory of Soft Matter Chemistry Department of Polymer Science and Engineering University of Science and Technology of China Institutes of Physical Science and Information Technology Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education Anhui University

Polyolefin vitrimers are polymer networks bearing reversible covalent crosslinking points, enabling them to be reprocessed and recycled. In this contribution, a series of polyolefin vitrimers were designed based on the acetoacetate-functionalized polyolefin copolymers, which were produced through the direct copolymerization of ethylene with polar comonomers using a phosphinesulfonate palladium catalyst. The pendant acetoacetate group could mediate several characteristic reactions, such as the Michael addition reaction, ketone-amine condensation and metal coordination reaction. As such, structurally adjustable polyolefin vitrimers can be accessed by introducing various dynamic crosslinking bonds, including disulfide exchange, transamination of vinylogous urethane and labile metal coordination bond. The utilization of different crosslinking reactions and the mole ratio of crosslinkers significantly impact the material properties of the resultant polymers. Specifically, the generated polyolefin vitrimers demonstrated excellent reprocessability and closed-loop recycling properties. The study in this work provides an efficient strategy to access various polyolefin vitrimers.

关键词： polyolefin vitrimers acetoacetate group polar monomer olefin copolymerization

Superexchange and charge transfer in the nickelate superconductor La_(3)Ni_(2)O_(7) under pressure

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Science China(Physics,Mechanics & Astronomy) 2024年第11期67卷 1-8页

作者： Wéi Wú Zhihui Luo Dao-Xin yao Meng wang Center for Neutron Science and Technology Guangdong Provincial Key Laboratory of Magnetoelectric Physics and DevicesSchool of PhysicsSun Yat-sen UniversityGuangzhou 510275China

Recently, a bulk nickelate superconductor La_(3)Ni_(2)O_(7) is discovered at pressures with a remarkable high transition temperature T_(c)~ 80 K. Here, we study a Hubbard model with tight-binding parameters derived from ab initio calculations of La_(3)Ni_(2)O_(7),by employing large scale determinant quantum Monte Carlo and cellular dynamical mean-field theory. Our result suggests that the superexchange couplings in this system are comparable to that of cuprates. The system is a charge transfer insulator as the hole concentration becomes four per site at large Hubbard U. Upon hole doping, two low-energy spin-singlet bands emerge in the system exhibiting distinct correlation properties: while the one composed of the out-of-plane Ni-d_(3z^(2)-r^(2)) and O-p_(z) orbitals demonstrates strong antiferromagnetic correlations and narrow effective bandwidth, the in-plane singlet band consisting of the Ni-d_(x^(2)-y^(2)) and O-p_(x)/p_(y) orbitals is in general more itinerant. Over a broad range of hole doping, the doped holes occupy primarily the d_(x^(2)-y^(2)) and p_(x)/p_(y) orbitals, whereas the d_(3z^(2)-r^(2)) and p_(z) orbitals retain underdoped. We propose an effective t-J model to capture the relevant physics and discuss the implications of our result for comprehending the La_(3)Ni_(2)O_(7) superconductivity.

关键词： superconductivity nickelate superconductors Hubbard model superexchange charge transfer insulator quantum Monte Carlo

Worm-like micelles facilitate the intestinal mucus diffusion and drug accumulation for enhancing colorectal cancer therapy

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Chinese Chemical Letters 2024年第6期35卷 427-432页

作者： yihan Zhou Duo Gao yaying wang Li Liang Qingyu Zhang Wenwen Han Jie wang Chunliu Zhu Xinxin Zhang yong Gan State Key Laboratory of Drug Research and Center of Pharmaceutics Shanghai Institute of Materia MedicaChinese Academy of SciencesShanghai 201203China School of Chinese Materia Medica Nanjing University of Chinese MedicineNanjing 210023China University of Chinese Academy of Sciences Beijing 100049China NMPA Key Laboratory for Quality Research and Evaluation of Pharmaceutical Excipients National Institutes for Food and Drug ControlBeijing 100050China School of Pharmacy Shanghai University of Traditional Chinese MedicineShanghai 201203China

Local delivery of nanoparticles holds promise for colorectal cancer(CRC)***,the presence of the mucus layer on the epithelium poses a significant challenge to drug delivery,thereby adversely affecting treatment *** is crucial to develop efficient drug delivery carriers that can effectively overcome mucus barriers to treat colorectal ***,we utilized poly(1,4-butadiene)-b-poly(ethylene oxide)polymers to prepare four distinct geometries of polymeric micelles,namely linear micelles(LMs),worm-like micelles(WLMs),large spherical micelles(LSMs),and small spherical micelles(SSMs)to investigate the influence of shape effects on overcoming colonic mucosal *** found that the carriers exhibited diverse shapes while maintaining comparable physicochemical *** these,WLMs had an aspect ratio similar to segmented filamentous bacteria,which exhibited superior mucus penetration ability,leading to prolonged drug release kinetics and faster entry into epithelial cells compared to ***,rectally administrated 10-hydroxycamptothecin-loaded WLMs traversed the colorectal mucus in orthotopic CRC nude mice model,penetrated and accumulated within tumor tissue,and effectively aggregated within cancer cells,thereby inducing significantly robust antitumor outcomes in *** findings underscore the significance of shape design in overcoming colonic mucosal absorption barriers,offering a novel approach for the development of drug delivery carriers tailored for effective tumor therapy.

关键词： Worm-like micelles Mucus penetration Shape dependent Transmucosal delivery Colorectal cancer

New insights into component matching mechanism in the compression system of double bypass engine

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Propulsion and Power Research 2024年第1期13卷 118-131页

作者： Ruoyu wang Xianjun yu baojie Liu Guangfeng An Research Institute of Aero-Engine Beihang UniversityBeijing 100191China National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics Beihang UniversityBeijing 100191China

Variable cycle engine(VCE)is one of the most promising technologies for the next-generation aircraft,the matching of different components in the compression system is a key difﬁculty VCE *** investigate the component matching mechanisms in the VCE compression system,an advanced throughflow program is employed to calculate the characteristic lines of each component,and a zero-dimensional method is developed to cap-ture the component performance deviation during the coupling working *** setting the compressor stall and choke conditions as the boundary,the operation range of the compression system isﬁrst clariﬁed,and the aerodynamic performance in the operation zone is discussed,thus providing a theoretical basis for optimization of the engine operating con-trol *** show that the efﬁciency of the coreflow is optimum at the left-bottom corner of the operation region,while the total pressure ratio peaks at the right-top area,hence a balance is needed when deciding the matching *** of component control pa-rameters will change the position of the operation zone,as well as the corresponding aerody-namic *** the core driven fan stage rotating speed can improve the total bypass ratio,yet the total pressure ratio of the coreflow will be *** the core driven fan stage inlet guide vane can increase the total bypass ratio without changing the core flow aerodynamic performance *** bypass ratio of the compression system can also be increased by increasing the fan stall margin or decreasing its rotating speed,both ways will decrease the total pressure ratio of the core *** of the study will benefit the variable cycle engine design process in operation point evaluation and thermodynamic cycle optimization.

关键词： Matching analysis Double bypass engine Compression system Operation zone Aerodynamic performance