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Electromagnetic wave absorption and mechanical properties of SiC nanowire/low-melting-point glass composites sintered at 580°C in air

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International Journal of Minerals,Metallurgy and Materials 2023年第9期30卷 1809-1815页

作者： Ranran Shi Wei Lin Zheng liu Junna Xu Jianlei Kuang wenxiu liu Qi Wang Wenbin Cao Department of Inorganic Nonmetallic Materials School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China National Demonstration Center for Materials Education Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China Beijing Institute of Aeronautical Materials Aero Engine Corporation of ChinaBeijing 100095China School of Materials and Environmental Engineering Hunan University of HumanitiesScience and TechnologyLoudi 417000China

Si C nanowires are excellent high-temperature electromagnetic wave (EMW) absorbing materials. However, their polymer matrix composites are difficult to work at temperatures above 300℃, while their ceramic matrix composites must be prepared above 1000℃ in an inert atmosphere. Thus, for addressing the abovementioned problems, SiC/low-melting-point glass composites were well designed and prepared at 580℃ in an air atmosphere. Based on the X-ray diffraction results, SiC nanowires were not oxidized during air atmosphere sintering because of the low sintering temperature. Additionally, SiC nanowires were uniformly distributed in the glass matrix material. The composites exhibited good mechanical and EMW absorption properties. As the filling ratio of SiC nanowires increased from 5wt%to 20wt%, the Vickers hardness and flexural strength of the composite reached HV 564 and 213 MPa, which were improved by 27.7%and 72.8%, respectively, compared with the low-melting-point glass. Meanwhile, the dielectric loss and EMW absorption ability of SiC nanowires at 8.2–12.4 GHz were also gradually improved. The dielectric loss ability of low-melting-point glass was close to 0. However, when the filling ratio of SiC nanowires was 20wt%, the composite showed a minimum reflection loss (RL) of-20.2 dB and an effective absorption (RL≤-10 dB) bandwidth of2.3 GHz at an absorber layer thickness of 2.3 mm. The synergistic effect of polarization loss and conductivity loss in SiC nanowires was responsible for this improvement.

关键词： SiC nanowires glass composite flexural strength dielectric properties microwave absorption

Synthesis of Cu–TiO2/CuS p-n heterojunction via in situ sulfidation for highly efficient photocatalytic NO removal

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Progress in Natural Science:Materials International 2022年第5期32卷 561-569页

作者： Faguo Wang Shuo Yang Sumei Han Peng Sun wenxiu liu Qipeng Lu Wenbin Cao School of Materials Science and Engineering University of Science and Technology Beijing Institute of Urban Safety and Environmental Science Beijing Academic of Science and Technology

Cu doped TiO2/CuS(Cu–TiO2/CuS) p-n heterojunction was synthesized via in situ sulfidation method for efficient photocatalytic removal of NO at ppb-level. The results show that optimized Cu–TiO2/CuS heterojunction possessed a maximum efficiency of 85% for the removal of NO under visible light irradiation, which was approximately 8.5, 4.3 and 1.2 times that of CuS, TiO2and Cu–TiO2, respectively. The improved photocatalytic performance is attributed to the enhancement of visible light absorption and charge carrier separation induced by the construction of p-n heterojunction. Meanwhile, the p-n heterojunction charge transfer mechanism of Cu–TiO2/CuS was verified by systematic investigations. The appropriate band structures of the two components and the internal electric field formed at the interface of the heterojunction were two factors for this charge transfer mechanism. Furthermore, the role of active species in NO removal was explored, and the corresponding mechanism for NO removal of the heterojunction was proposed. This work provides a promising approach for the synthesis of heterojunction photocatalysts and facilitates the application of photocatalysts in sustainable and efficient pollutant removal.

关键词： Cu doped TiO2/CuS p-n heterojunction In situ sulfidation Visible light NO removal

Introducing oxygen vacancies in TiO_(2) lattice through trivalent iron to enhance the photocatalytic removal of indoor NO

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International Journal of Minerals,Metallurgy and Materials 2023年第10期30卷 2025-2035页

作者： Peng Sun Sumei Han Jinhua liu Jingjing Zhang Shuo Yang Faguo Wang wenxiu liu Shu Yin Zhanwu Ning Wenbin Cao Institute of Urban Safety and Environmental Science Beijing Academy of Science and TechnologyBeijing 100054China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Beijing Wetech Environmental Sci-Tech Co. Ltd.Beijing 100083China Institute of Multidisciplinary Research for Advanced Materials(IMRAM) Tohoku UniversityKatahira 2-1-1Aoba-kuSendai 980-8577Japan Advanced Institute for Materials Research(WPI-AIMR) Tohoku UniversityKatahira 2-1-1Aoba-kuSendai 980-8577Japan Tianjin College University of Science and Technology BeijingTianjin 301830China

The synthesis of oxygen vacancies(OVs)-modified TiO_(2)under mild conditions is *** this work,OVs were easily introduced in TiO_(2)lattice during the hydrothermal doping process of trivalent iron *** calculations based on a novel charge-compensation structure model were employed with experimental methods to reveal the intrinsic photocatalytic mechanism of Fe-doped TiO_(2)(Fe-TiO_(2)).The OVs formation energy in Fe-TiO_(2)(1.12 eV)was only 23.6%of that in TiO_(2)(4.74 eV),explaining why Fe^(3+)doping could introduce OVs in the TiO_(2)*** calculation results also indicated that impurity states introduced by Fe^(3+)and OVs enhanced the light absorption activity of TiO_(2).Additionally,charge carrier transport was investigated through the carrier lifetime and relative *** carrier lifetime of Fe-TiO_(2)(4.00,4.10,and 3.34 ns for 1at%,2at%,and 3at%doping contents,respectively)was longer than that of undoped TiO_(2)(3.22 ns),indicating that Fe^(3+) and OVs could promote charge carrier separation,which can be attributed to the larger relative effective mass of electrons and ***,Fe-TiO_(2)has higher photocatalytic indoor NO removal activity compared with other photocatalysts because it has strong light absorption activity and high carrier separation efficiency.

关键词： oxygen vacancies density functional theory calculations iron-doped titanium dioxide carrier separation photocatalytic removal of indoor nitric oxide

Advances in environmental behaviors and effects of dissolved organic matter in aquatic ecosystems

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Science China Earth Sciences 2016年第4期59卷 746-759页

作者： HE Wei BAI ZeLin LI YiLong KONG XiangZhen liu wenxiu YANG Chen YANG Bin XU Fuliu MOE Laboratory for Earth Surface Processes College of Urban & Environmental Sciences Peking University

Dissolved organic matter(DOM) is a group of compounds that have complex chemical structures and multiple interactions with their surrounding materials. More than one trillion tons of DOM are stocked in the world's aquatic ecosystems. DOM is a very important part of aquatic ecosystem productivity and plays a crucial role in global carbon cycling. DOM has rich environmental behaviors and effects such as influencing the bioavailability of contaminants, serving as an important inducer of reactive oxygen species(ROS), and protecting aquatic organisms from the harm of dangerous ultraviolet radiation. There have been many systematic studies on the composition, structure, and sources of DOM because such studies are much easier to conduct than studies on the environmental behaviors and effects of DOM. Due to many factors, the research systems of DOM's environmental behaviors and effects are still being developed and have become a hotspot of environmental science. This review paper focuses on some critical progress, problems, and trends of DOM's environmental behaviors and effects in aquatic ecosystems, including mutual exchange mechanisms between DOM and particulate organic matter(POM) with influencing factors, photochemical behaviors of DOM especially inducing ROS, binding interactions between DOM and anthropogenic organic contaminants(AOC), interactions between DOM and microorganisms, effects of DOM on pollutants' bioavailability, ecotoxicity, and ecological risks. Hopefully, this paper will contribute to a more systematic understanding of the DOM environmental behaviors and effects and to promoting further relevant studies.

关键词： Dissolved organic matter Mutual exchange mechanisms Photochemical behavior Binding interaction Bioavailability

Vacancy-engineering-mediated activation of excitonic transition for boosting visible-light-driven photocatalytic oxidative coupling of amines

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Nano Research 2023年第11期16卷 12655-12661页

作者： wenxiu liu Lei Li Peng Zhang Manqin Guan Ming Zuo Yinhua Zhao Hui Wang Xiaodong Zhang Yi Xie Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Institute of Energy Hefei Comprehensive National Science CenterHefei 230031China

The light absorption properties of semiconductor-based photocatalysts to a large extent determine the relevant catalytic *** strategies in broadening the light absorption range are usually accompanied with unfavorable changes in redox ability and dynamics of photoinduced species that would confuse the comprehensive *** this work,we propose a nontrivial excitonic transition regulation strategy for gaining sub-bandgap light absorption in low-dimensional semiconductor-based *** bismuth oxybromide(BiOBr)as a model system,we highlight that the light absorption cut-off edge could be effectively extended up to 500 nm by introducing Bi *** the basis of theoretical simulations and spectroscopic analyses,we attributed the broadening of light absorption to the promotion of excitonic transition that is generally forbidden in pristine BiOBr system,associated with Bi-vacancy-induced excited-state symmetry *** addition,Bi vacancy was demonstrated to implement negligible effects on other photoexcitation properties like excited-state energy-level profiles and *** from these features,the defective sample exhibits a notable advantage in gaining visible-light-driven photocatalytic reactions.

关键词： semiconductor-based photocatalysts light absorption vacancy engineering excitonic transition selective oxidation

Calcium-Sensing Receptor of Immune Cells and Diseases

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Cardiovascular Innovations and Applications 2021年第2期5卷 257-266页

作者： wenxiu liu Yutong Guo MM Yue liu Jiaxing Sun Xinhua Yin Department of Cardiology The First Affi liated Hospital of Harbin Medical UniversityHarbin150001 HeilongjiangChina

Calcium-sensing receptor(CaSR),which was initially found in the parathyroid gland,is ubiquitously expressed and exerts specifi c functions in multiple cells,including immune *** is functionally expressed on neutrophils,monocytes/macrophages,and T lymphocytes,but not B lymphocytes,and regulates cell functions,such as cytokine secretion,chemotaxis,phenotype switching,and ligand *** these immune cells,CaSR is involved in the development of many diseases,such as sepsis,cryopyrin-associated periodic syndromes,rheumatism,myocardial infarction,diabetes,and peripheral artery *** its discovery,it has been controversial whether CaSR is expressed and plays a role in immune *** article reviews current knowledge of the role of CaSR in immune cells.

关键词： Calcium-sensing receptor neutrophil monocyte/macrophage T lymphocyte B lymphocyte

Several Problems in the Development of Basic Disciplines

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Systems Science and Systems Engineering 1993年第1期3卷 47-56页

作者： CHEN Shijun, HAN wenxiu, liu Shuhua, XU Xuejun Tianjin University, Tianjin, China

In this paper, several problems related to the development of basic disciplines are expounded from macroscopic visual angle. First, four important concepts(basic science, basic discipline, basic research, fundamental research) are analyzed. Then, reserve strength for the development of basic disciplines in China is considered in accordance with funds that have been put into basic research. Finally, several theoretical cognition problems concerning the development of basic disciplines (such as social function of science, motive force for the development of basic disciplines, as well as soft environment and cultural atmosphere favourable to it) are discussed.

关键词： basic science basic disciplines basic research fundamental research.

Engineering Exciton-Phonon Interactions for Suppressing Nonradiative Energy Loss in Energy-Transfer-Initiated Photocatalysis

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CCS Chemistry 2023年第1期5卷 234-244页

作者： Hui Wang Sen Jin Aolei Wang Xiang Jiang wenxiu liu Xiaodong Zhang Wensheng Yan Kuai Yu Jin Zhao Yi Xie Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefeiAnhui 230026 Institute of Energy Hefei Comprehensive National Science CenterHefeiAnhui 230031 Department of Physics CAS Key Laboratory of Strongly-Coupled Quantum Matter PhysicsInternational Center for Quantum Design of Functional MaterialsUniversity of Science and Technology of ChinaHefeiAnhui 230026 National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefeiAnhui 230029 Institute of Microscale Optoelectronics Shenzhen UniversityShenzhenGuangdong 518060 Department of Physics and Astronomy University of PittsburghPittsburghPA 15260 CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefeiAnhui 230031

The prevalent excitonic effects in low-dimensional semiconductors enable energy-transfer-initiated photocatalytic solar-to-chemical energy ***,the generally strong interactions between excitons and lattice vibrations in these low-dimensional systems lead to robust nonradiative energy loss,which inevitably impedes photocatalytic performance of energy-transfer-initiated ***,we highlight the crucial role of engineering exciton-phonon interactions in suppressing nonradiative energy losses in low-dimensional semiconductor-based *** taking bismuth oxybromide(BiOBr)as an example,we demonstrate that phonon engineering could be effectively implemented by introducing Bi-Br vacancy *** on nonadiabatic molecular dynamics simulations and spectroscopic investigations,we demonstrate that the defective structure can promote exciton-low-frequency phonon coupling and reduce exciton-high-frequency optical phonon *** from the tailored couplings,nonradiative decay of excitons in defective BiOBr is significantly suppressed,thereby facilitating exciton accumulation and hence energy-transfer-initiated photocatalysis.

关键词： photocatalysis exciton-phonon interaction nonradiative decays energy transfer

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现代汉语“有+N”结构的构式分析

语言教学与研究 2017年第3期 103-112页

作者：刘文秀西北民族大学文学院 730030

文章尝试将"有品位、有身份"等"有+N"结构纳入构式语法的体系进行研究。首先通过实际用例的分析,从共时层面总结出"有+N"的构式义为朝着持有者所希望的、正向积极的方向凸显出对某种特性或事物远高于社会平均值的拥有。接着对能进入该... 详细信息

文章尝试将"有品位、有身份"等"有+N"结构纳入构式语法的体系进行研究。首先通过实际用例的分析,从共时层面总结出"有+N"的构式义为朝着持有者所希望的、正向积极的方向凸显出对某种特性或事物远高于社会平均值的拥有。接着对能进入该构式的N所具有的语义特征进行梳理,发现具有普遍可占有性的特征、拥有描述性语义成分以及语义色彩为中性或褒义的词更容易进入该构式。最后刻画了构式义与构件义的互动关系,指出两者处于互相影响和渗透的过程之中,一方面构件义会制约构式义的浮现和凸显,另一方面在一定条件下部分构式义会融入构件义。

关键词： “有+N” 构式义语义特征互动关系