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Groove formation on Phobos from reimpacting orbital ejecta of the Stickney crater

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Earth and Planetary Physics 2022年第3期6卷 294-303页

作者： XiangYu Xi Min Ding menghua zhu State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacaoChina China National Space Administration Macao Center for Space Exploration and ScienceMacaoChina

Numerous linear grooves have long been recognized as covering the surface of Phobos, but the mechanisms of their formation are still unclear. One possible mechanism is related to the largest crater on Phobos, the Stickney crater, whose impact ejecta may slide,roll, bounce, and engrave groove-like features on Phobos. When the launch velocity is higher than the escape velocity, the impact ejecta can escape Phobos. A portion of these high-velocity ejecta are dragged by the gravitational force of Mars, fall back, and reimpact Phobos.In this research, we numerically test the hypothesis that the orbital ejecta of the Stickney crater that reimpact Phobos could be responsible for a particular subset of the observed grooves on Phobos. We adopt impact hydrocode i SALE-2 D(impact-Simplified Arbitrary Lagrangian Eulerian, two-dimensional) to simulate the formation of the Stickney crater and track its impact ejecta, with a focus on orbital ejecta with launch velocities greater than the escape velocity of Phobos. The launch velocity distribution of the ejecta particles is then used to calculate their trajectories in space and determine their fates. For orbital ejecta reimpacting Phobos, we then apply the sliding boulder model to calculate the ejecta paths, which are compared with the observed groove distribution and length to search for causal relationships. Our ejecta trajectory calculations suggest that only ~1% of the orbital ejecta from the Stickney crater can reimpact Phobos. Applying the sliding boulder model, we predict ejecta sliding paths of 9-20 km in a westward direction to the east of the zone of avoidance, closely matching the observed grooves in that region. The best-fit model assumes an ejecta radius of ~150 m and a speed restitution coefficient of 0.3, consistent with the expected ejecta and regolith properties. Our calculations thus suggest the groove class located to the east of the zone of avoidance may have been caused by reimpact orbital ejecta from the Stickney crater.

关键词： Phobos groove formation Stickney crater reimpact ejecta

Perovskite films for X-ray detection

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Journal of Semiconductors 2022年第7期43卷 4-7页

作者： Pei Yuan Lixiu Zhang menghua zhu Liming Ding State Key Laboratory of Solidification Processing Key Laboratory of Radiation Detection Materials and DevicesSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Center for Excellence in Nanoscience(CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication(CAS)National Center for Nanoscience and TechnologyBeijing 100190China

X-ray detection is widely used in research[1−3],product in-spection[4],nuclear station,and medical imaging.Si[5],α-Se[6],PbI2[7],and CdZnTe[8]are conventional semiconductors,and some problems limit their applications.For instance,Si andα-Se have low stopping power for X-ray[8],which hinders their application in high-energy range over 50 keV.Moreover,the complicated preparation,high operating voltage,and high fab-rication cost of these materials are the negative issues.

关键词： PbI2 instance hinder

Novel high-voltage cathode for aqueous zinc ion batteries:Porous K_(0.5)VOPO_(4)·1.5H_(2)O with reversible solid-solution intercalation and conversion storage mechanism

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Journal of Energy Chemistry 2024年第6期93卷 71-78,I0003页

作者： Liyu Wang Mingliang Zhao Xiaoyu Zhang menghua Wu Yu Zong Yu Chen Xinliang Huang Mingjie Xing Xin Ning Wen Wen Daming zhu Xiaochuan Ren Industrial Research Institute of Nonwovens&Technical Textiles College of Textiles&ClothingShandong Engineering Research Center for Specialty Nonwoven MaterialsQingdao UniversityQingdao 266071ShandongChina Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China

Cathode materials that possess high output voltage,as well as those that can be mass-produced using facile techniques,are crucial for the advancement of aqueous zinc-ion battery(ZIBs)applications,Herein,we present for the first time a new porous K_(0.5)VOPO_(4)·1.5H_(2)O polyanionic cathode(P-KIVP)with high output voltage(above 1.2 V)that can be manufactured at room temperature using straightforward coprecipitation and etching techniques.The P-KVP cathode experiences anisotropic crystal plane expansion via a sequential solid-solution intercalation and phase co nversion pathway throughout the Zn^(2+)storage process,as confirmed by in-situ synchrotron X-ray diffraction and ex-situ X-ray photoelectron spectroscopy.Similar to other layered vanadium-based polyanionic materials,the P-KVP cathode experiences a progressive decline in voltage during the cycle,which is demonstrated to be caused by the irreversible conversion into amorphous VO_(x).By introducing a new electrolyte containing Zn(OTF)_(2) to a mixed triethyl phosphate and water solution,it is possible to impede this irreversible conversion and obtain a high output voltage and longer cycle life by forming a P-rich cathode electrolyte interface layer.As a proof-of-concept,the flexible fiber-shaped ZIBs based on modified electrolyte woven into a fabric watch band can power an electronic watch,highlighting the application potential of P-KVP cathode.

关键词： Aqueous zinc ion battery Cathode Porous material High voltage platform In-situ synchrotron X-ray diffraction

Effect of dimensional expansion on carrier transport behaviors of the hexagonal Bi-based perovskite crystals

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Journal of Energy Chemistry 2022年第3期31卷 459-465,I0013页

作者： Qihao Sun Bao Xiao Leilei Ji Dou Zhao Jinjin Liu Wei Zhang menghua zhu Wanqi Jie Bin-Bin Zhang Yadong Xu State Key Laboratory of Solidification Processing&Key Laboratory of Radiation Detection Materials and Devices MIITSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710072ShaanxiChina College of Chemistry Nankai UniversityTianjin 300071China School of Microelectronics Xidian UniversityXi’an 710072ShaanxiChina

All-inorganic Cs_(3)Bi_(2)I_(9)(CBI)halide perovskites are sought to be candidate for photoelectrical materials because of their low toxicity and satisfactory stability.Unfortunately,the discrete molecular[Bi2I9]3−clusters limit the charge-transport behaviors.Herein,the defect halide perovskite based on trivalent Bi^(3+)is expanded to Cs_(3)Bi_(2)I_(6)Br_(3)(CBIB).Centimeter-size CBIB single crystal(Φ15×70 mm^(3))was grown by the vertical Bridgeman method.The powder X-ray diffraction analysis shows that CBIB has structure with lattice parameters of a=b=8.223Å,c=10.024Å,α=β=90°andγ=120°.The density functional theory(DFT)calculations demonstrate that the charge density distribution was enhanced after the dimensional expansion.The enhancement of carrier transport ability of(00l)in-plane is characterized before and after dimensional improvement.The obtained CBIB(001)exhibited an electron mobility up to 40.03 cm^(2)V^(−1)s^(−1)by time-of-flight(TOF)technique,higher than 26.46 cm^(2)V^(−1)s^(−1)of CBI(001).Furthermore,the X-ray sensitivity increases from 707.81μC Gy^(−1)cm^(−2)for CBI(001)to 3194.59μC Gy−1 cm^(−2)for CBIB(001).This research will deepen our understanding of Bi-based perovskite materials and afford more promising strategies for lead-free perovskite optoelectronic devices modification.

关键词： Bi-based perovskite Dimensional expansion Carrier transport Bridgeman method Radiation detection

Orientation and mobility control of 4HCB organic film for flexible X-ray detectors with high performance

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Journal of Materials Science & Technology 2023年第4期135卷 46-53页

作者： Meng Xu menghua zhu Dou Zhao Sixin Chen Shilin Liu Quanchao Zhang Pei Yuan Binbin Zhang Paul Sellin Wanqi Jie Yadong Xu State Key Laboratory of Solidification Processing MIIT Key Laboratory of Radiation Detection Materials and Devicesand School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Department of Physics University of SurreyGuildford GU27XHUK

In comparison to inorganic counterparts,organic semiconducting(OSC)crystalline films are promising for building large-area and flexible ionizing radiation detectors for X-ray imaging or dosimetry due to their tissue equivalence,simple processing and large-scale production accessibility.Fabrication processes,how-ever,hinder the ability to generate aligned and large-area films with high carrier mobility.In this work,the space-confined melt process is used to produce highly orientated 4HCB(4-hydroxycyanobenzene)OSC films with a large area of 15×18 mm^(2).The out-of-plane direction of the 4HCB film is,and the benzene rings are found to be extensively overlapped inside the in-plane direction,according to the XRD patterns.The film exhibits a high resistivity up to 1012cm,and high hole mobility of 10.62 cm^(2)V^(−1)s^(−1).Furthermore,the 4HCB(80μm-thick film)based X-ray detectors can achieve a sensitivity of 93μC Gy air^(−1) cm^(−2)and on/offratio of 157.The device also shows steady flexibility,with no degradation in detecting function after 100 cycles of bending.Finally,the proposed 4HCB film detectors demonstrated a high-resolution X-ray imaging capability.The imaging of several materials with sharp edges(copper and polytetrafluoroethylene)has been obtained.This work has developed a fast but efficient approach for producing large-area,highly oriented OSC films for high-performance X-ray detectors.

关键词： Organic semiconducting films Highly oriented X-ray Detector X-ray imaging Wearable detector

Template directed perovskite X-ray detectors towards low ionic migration and low interpixel cross talking

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Fundamental Research 2022年第1期2卷 108-113页

作者： menghua zhu Xinyuan Du Guangda Niu Weiwei Liu Weicheng Pan Jincong Pang Wenyu Wang Chao Chen Yadong Xu Jiang Tang Wuhan National Laboratory for Optolecroricis(WNLO)and School of Optical and Eectronic Ifrmnation Huazhong University of Science and Technology(HUST)Wuhan 430074China Schoo of Materials Science and Engineering Northwester Polytechrnical UniversityXi'an 710072China

The metal halide perovskites exhibit excellent performance as the direct X-ray detectors owing to their strong absorption capability,long carrier lifetime and diffusion length,radiation ruggedness,etc.For imaging applications,the ionic migration of perovskites and charge sharing effect between the adjacent pixels have a significantly negative impact on the spatial resolution.Herein,for the first time,the porous anodic aluminum oxides(AAO)have been used as a template to grow the CsPbBr2I thick film for the direct X-ray detection.Benefiting from the oxygen passivation effect,the activation energy for ionic migration has been observed to increase to 0.701 eV,whereas the dark current drift(1.01×10^(-5)nA cm^(-1)s^(-1)V^(-1))is one to two orders of magnitude lower than the other lead halide perovskite single crystals and films.Moreover,the AAO insulating wall effectively blocks the charge diffusion effect across a pixel pitch of 10^m.Overall,the findings reported in this study open a new route for reducing the ionic migration and pixel crosstalk,thus,bringing the perovskite X-ray detectors close to the practical applications.

关键词： Aluminum oxides(AAO) Perovskite X-ray detection Crosstalk

Flexible asymmetric supercapacitor with high energy density based on optimized MnO_2 cathode and Fe_2O_3 anode

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Chinese Chemical Letters 2019年第3期30卷 750-756页

作者： Weiwei Liu menghua zhu Jinghua Liu Xin Li Jian Liu Department of Chemistry and Chemical Engineering Harbin Institute of Technology State Key Lab of Urban Water Resource and Environment Harbin Institute of Technology College of Materials Science and Engineering Qingdao University of Science and Technology

All-so lid-state flexible supercapacitors have shown great potential in wearable and portable electronics.In this work, a flexible asymmetric pseudocapacitor(FAPC) is fabricated by using MnO_2 nanosheetscarbon fabric as cathode and Fe_2O_3 nanowire-carbon fabric as anode in the presence of PVA-LiCl as gel electrolyte. With high area capacitances of MnO_2 and Fe_2O_3 based electrodes by optimizing the reaction conditions, the device shows high working potential of 1.8 V, high area capacitance of 83.3 mF/cm^2(119 F/g), stable cycling performance with 82.3% of capacitance retention after 5000 cycles, and a competitive energy density of 53.55 Wh/kg in the broader context of MnO_2-based supercapacitors. In addition, the FAPC demonstrates excellent mechanical stability and flexibility with negligible degradation of electrochemical performance after numerous bending tests, establishing it as a promising candidate for portable and wearable energy storage.

关键词： Flexible Asymmetric supercapacitor MnO2 Fe2O3 All-solid-state Optimization

场域理论视角下师范生从教意愿的影响机制研究——基于两所师范高校的调查分析

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中国高教研究 2024年第1期 79-85页

作者：李佳丽梁会青赵楷朱梦华上海师范大学教育学院教育部“教育大数据与教育决策”实验室上海200234 河南大学教育学部河南开封475001 岭南大学中国香港999077

基于场域理论和师范生职业认同发展理论分析学术场域、实践场域、师范生职业认同和从教意愿之间的关系。相较于实践场域,学术场域在提高师范生职业认同的内在价值认同、从教意愿中扮演更重要的角色;学术场域中的高校教师素养和教师从教... 详细信息

基于场域理论和师范生职业认同发展理论分析学术场域、实践场域、师范生职业认同和从教意愿之间的关系。相较于实践场域,学术场域在提高师范生职业认同的内在价值认同、从教意愿中扮演更重要的角色;学术场域中的高校教师素养和教师从教支持既能直接提高师范生从教意愿,又能通过正向影响内在价值认同间接提高从教意愿;而高校硬件经济支持、朋辈支持只能直接影响从教意愿;实践场域对师范生的从教意愿直接影响作用显著为负,参与实习学校管理与事务性活动是降低从教意愿的主要原因,但实习指导教师素养能通过正向影响师范生的内在价值认同间接提高从教意愿,缓解实践场域中管理与事务性活动参与的负向影响作用。

关键词：学术场域实践场域师范生职业认同从教意愿

A novel conformationally adaptive macrocyclic tetramaleimide with flipping pyrene sidewalls

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Chinese Chemical Letters 2022年第1期33卷 229-233页

作者： Lingyun zhu Wei Zeng menghua Li Meijin Lin Key Laboratory of Molecule Synthesis and Function Discovery and Fujian Provincial Key Laboratory of Electrochemical Energy Storage MaterialsCollege of ChemistryFuzhou UniversityFuzhou 350116 China College of Materials Science and Engineering Fuzhou UniversityFuzhou 350116China

The synthesis,structure,and properties of pyrene-based conformationally adaptive macrocycles are described.This new type of conformationally adaptive macrocycle was constructed through Perkin reaction,followed by imidization.By changing the condensation partner as the linking unit,a family of conjugated macrocycles with different sizes of the cavity was synthesized,which provide a simple and modular synthetic strategy towards the conformationally adaptive macrocycles.Furthermore,the macrocycles provide two well-defined conformations through flipping pyrene subunit,which were unambiguously determined by single-crystal X-ray diffraction analysis.The conformational interconversion barrier was determined by density functional theory(DFT)calculations.This new macrocycle also demonstrated unique properties,such as vapochromic behavior and aggregation emission enhancement effect.Furthermore,we have also investigated the effect of the linker on the shape and photophysical properties of the resulting macrocyclic products.

关键词： AEE Conjugated macrocycles DFT Flipping sidewalls Vapochromic