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EPR study of charge separation associated states and reversibility of surface bound superoxide radicals in SrTiO_(3) photocatalyst

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Journal of Energy Chemistry 2022年第7期31卷 388-393,I0011页

作者： xianwen zhang Zheng Li Bin Zeng Can Li Hongxian Han State Key Laboratory of Catalysis and Dalian National Laboratory for Clean Energy Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina University of Chinese Academy of Sciences Beijing 100049China

Understanding the processes of charge generation, transfer and capture is important for the design and synthesis of efficient photocatalysts. In this work, light-induced charge separation and effect of O_(2) on electron transfer processes in SrTiO_(3) were investigated by electron paramagnetic resonance(EPR). It was found that photoinduced electron transfer from O_(2)- to Ti^(4+) produced Ti^(3+) and O- redox radical pairs under vacuum condition. Under oxygen atmosphere, however, surface bound superoxide radicals O_(2)-were formed by electron reduction of adsorbed oxygen at initial photoirradiation stage, and quenched by the reverse electron transfer to Ti^(4+) upon further photoirradiation. Formation of long-lived charge separation associated [Ti^(3+)---O-] species and the reversibility of surface bound superoxide radicals mediating the processes of photogenerated electrons may be accountable for the high activity of SrTiO_(3) in photocatalytic water splitting reaction.

关键词： Photocatalyst Electron paramagnetic resonance Charge separation Superoxide radicals

A ballistocardiogram measurement system for home monitoring:design,performance,and evaluation

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Chinese Science Bulletin 2014年第23期59卷 2909-2917页

作者： Xinrong Cao Jie Wang xianwen zhang Jintian Tang Institute of Medical Physics and Engineering Tsinghua University

We present a ballistocardiogram(BCG)measurement system for obtaining the BCG *** performance of the BCG measurement system was tested,including the dynamic response frequency of the platform(32 Hz with a 75 kg load),and the signal to noise ratio of the system(minimum 23 dB).Factors that could influence BCG recording during measurement were investigated by collecting data from 48 healthy subjects(28 males and 20females).The basic features of the BCG signal,such as the amplitude and time interval,were extracted,and differences by gender were analyzed.A correlation between the IJ amplitude(amplitude difference between I-and J-peak)and the respiration phase was found(R2=0.49).The BCG signals for both sitting(SiBCG)and standing(StBCG)postures were obtained using this *** showed that the StBCG amplitudes were larger than those of SiBCG but there was no significant difference in the time *** robustness of our system was verified,and its potential for non-invasive cardiac activity monitoring was demonstrated.

关键词：冲击测量系统性能评价信号传送设计监控家庭时间间隔卡介苗

THE ENERGY CONSERVATION OF VLASOV-POISSON SYSTEMS

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Acta Mathematica Scientia 2023年第2期43卷 668-674页

作者：吴景鹏张显文 School of Mathematics and Statistics Huazhong University of Science and TechnologyWuhan 430074China

We prove that energy conservation holds for weak solutions to classical VlasovPoisson systems with proper *** particular,there exists a solution that conserves energy with|v|^(m)f0∈L^(1)_(x,v)for m>9/4.

关键词： Vlasov-Poisson system weak solutions energy conservation

Magnetic and optical properties of NaGdF4：Nd^3＋, Yb^3＋, Tm^3＋ nanocrystals with upconversion/downconversion luminescence from visible to the near-infrared second window

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Nano Research 2015年第2期8卷 636-648页

作者： xianwen zhang Zhi Zhao Xin zhang David B. Cordes Brandon Weeks Bensheng Qiu Kailasnath Madanan Dhiraj Sardar Jharna Chaudhuri Department of Mechanical Engineering Texas Tech University Lubbock Texas 79409 USA Hefei National Laboratory for Physical Sciences at the Microscale Hefei Anhui 230026 China Department of Chemical Engineering Texas Tech University Lubbock Texas 79409 USA Department of Chemistry & Biochemistry Texas Tech University Lubbock Texas 79409 USA EaStCHEM School of Chemistry University of St. Andrews St. Andrews KY16 9ST UK School of Information Science and Technology University of Science and Technology of China Hefei Anhui 230026 China Department of Physics and Astronomy University of Texas at San Antonio San Antonio Texas 78249 USA International School of Photonics Cochin University of Science and Technology Kochi 682022 India

We have designed and synthesized NaGdF4：Nd^3＋, Yb^3＋, Tm^3＋. magnetic nano- phosphors with combined dual-mode downconversion （DC） and upconversion （UC） photoluminescence upon 800 run excitation. Hexagonal-phase NaGdF4：Nd^3＋, Yb^3＋, Tm^3＋ nanocrystals （NCs） with an average size of 21 nm were synthesized using a solvothermal approach. Nd^3＋, Yb^3＋, Tm^3＋ triple-doped NaGdF4 NCs exhibit a broad range of photoluminescence peaks covering a near infrared first/second window （860-900, 1,000, and 1,060 nm）, and visible emission including blue （475 nm）, green （520 and 542 nm） and yellow （587 nm） after excitation at 800 nm. A mechanism involving circulation of energy over Gd^3＋ sublattices as bridge ions and final trapping by the initial activator ions （Nd^3＋） has been proposed. Penetration depth studies indicate that NIR emission is easily detected even at a large tissue thickness of 10 mm. These paramagnetic nanophosphors demonstrate a large magnetization value of 1.88 emu/g at 20 kOe and longitudinal relaxivity value of 1.2537 mM-1.S-1 as a Tl-weighted magnetic resonance imaging contrast agent. These NaGdF4：Nd^3＋, Yb^3＋ Tm^3＋ NCs are promising for applications in biological and magnetic resonance imaging.

关键词： near-infrared second window photoluminescence energy transfer nanocrystals

Clinical characteristics of brain tumorrelated epilepsy and factors influencing the identification of epilepsy-associated tumors

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Acta Epileptologica 2020年第1期2卷 208-213页

作者： xianwen zhang Liaoyuan Zheng Jingfeng Duan Zongping Li Yufeng Tang Department of Neurology Mianyang Central HospitalMianyang 621000China. Department of Neurosurgery Mianyang Central HospitalMianyang 621000China.

Background:To analyze the clinical features of brain tumor-related epilepsy(BTRE)and explore the factors influencing the identification of epilepsy-associated tumor(EAT),in order to advance the clinical understanding of BTRE and ***:Intracranial tumor origin and location as well as the type of epilepsy were retrospectively reviewed in 153 BTRE *** patients were further divided into the EAT and non-EAT groups,and comparisons were made for age,sex,tumor origin and location,and epilepsy type between the two ***:The 153 BTRE patients were divided into 78 cases with primary intracranial tumor and 75 cases with tumor originating from extracranial metastasis,according to the origin of *** to the location of tumor,116 cases had tumor lesions located in the brain parenchyma,and 37 cases had tumor lesions located in the ***,in the group with a brain parenchyma location,77 cases had single lobular involvement,and 39 cases had multiple-lobular involvement;84 cases had tumor lesions located in one hemisphere and 32 cases in both *** to the type of epilepsy,92 cases had generalized seizures,and 61 cases had focal *** type of epilepsy did not significantly correlate with the origin of intracranial tumor,the location of tumor lesions(in brain parenchyma or meninges)(P>0.05),or the hemispherical location(in one or two hemispheres)of lesions(P>0.05),but was significantly related with the lobular localization of lesions(P<0.05).The 153 cases of BTRE consisted of 87 EAT and 66 non-EAT,with significant differences in the origin,location and type(being glioma/non-glioma)of *** regression analysis showed that the type of tumor(*** being glioma)served as an independent factor for EAT identification;the lower the World Health Organization grade of glioma,the more likely the EAT is to be diagnosed(P<0.05).Conclusion:The majority of BTRE patients in this study had tumors located in the brain par

关键词： Brain tumor-related epilepsy Epilepsy-associated tumor Glioma Epilepsy

Timing,Displacement and Growth Pattern of the Altyn Tagh Fault:A Review

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Acta Geologica Sinica(English Edition) 2017年第2期91卷 669-687页

作者： DAI Shuang DAI Wei ZHAO Zhenbin LUO Junhua QIANG Lei MA Xin zhang xianwen XU Jianjun Key Laboratory of Western China's Environmental Systems(Ministry of Education) College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China Gansu Bureau of Seismology Lanzhou 730000China

The Altyn Tagh Fault（ATF） is the longest, lithospheric scale and strike-slip fault in East Asia. In the last three decades, multidisciplinary studies focusing on the timing, displacement of strikeslip and growth mechanics of the ATF have made great progresses. Most studies revealed that the ATF is a sinistral strike-slip and thrust fault, which underwent multiple episodes of activation. The fault is oriented NEE with a length of 1600 km, but the direction, timing of activity and magnitude of its extension eastward are still unclear. The AFT was predominately active during the Mesozoic and Cenozoic, in relation to the Mesozoic collision of the Cimmerian continent（Qiangtang and Lhasa block） and Cenozoic collision of India with Asia. The AFT strike-slipped with a left-lateral displacement of ca. 400 km during the Cenozoic and the displacement were bigger in the western segment and stronger in the early stage of fault activation. The slip-rates in the Quaternary were bigger in the middle segment than in the western and eastern segment. We roughly estimated the Mesozoic displacement as ca. 150-300 km. The latest paleomagnetic data showed that the clockwise vertical-axis rotation did not take place in the huge basins（the Tarim and Qaidam） at both side of ATF during the Cenozoic, but the rotation happened in the small basins along the ATF. This rotation may play an important role on accommodating the tectonic deformation and displacement of the ATF. Even if we have achieved consensus for many issues related to the ATF, some issues still need to be study deeply; such as：（a） the temporal and spatial coupling relationship between the collision of Cimmerian continent with Asia and the history of AFT in the Mesozoic and（b） the tectonic deformation history which records by the sediments of the basins within and at both side of AFT and was constrained by a high-resolution and accurate chronology such as magnetostratigraphy and paleomagnetic data.

关键词： timing displacement of strike-slip growth paleomagnetism Altyn Tagh fault Proto-Tethys

ON THE TRANSPORT EQUATION WITH INTEGRAL BOUNDARY CONDITIONS AND ITS CONSERVAIVE LAW

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Applied Mathematics(A Journal of Chinese Universities) 1996年第1期11卷 33-42页

作者： zhang xianwen LIANG BENZHONG Department of Mathematics, Xinyang Teacher’s College, Xinyang 464000 Department of Mathematics Xinyang Teacher’s College Xinyang

The well-posedness for the time-dependent neutron transport equationwith integral boundary conditions is established in L^1 space. Some spectral propertiesof the transport operator are discussed, the dominant eigenval... 详细信息

关键词： Transport equation resolvent positive operator dominant eigenvalue stochastic C_0-semigroup.

GLOBAL CLASSICAL SOLUTIONS AND THE CLASSICAL LIMIT OF THE NON-RELATIVISTIC VLASOV-DARWIN SYSTEM WITH SMALL INITIAL DATA

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Acta Mathematica Scientia 2023年第5期43卷 2043-2060页

作者：麻雅娴张显文 Department of Mathematics North University of ChinaTaiyuan 030051China School of Mathematics and Statistics Huazhong University of Science and TechnologyWuhan430074China

We investigate the global classical solutions of the non-relativistic Vlasov-D arwin system with generalized variables(VDG)in three *** first prove the global existence and uniqueness for small initial data and derive the decay estimates of the Darwin ***,we show in this framework that the solutions converge in a pointwise sense to solutions of the classical Vlasov-Poisson system(VP)at the asymptotic rate of 1/c2 as the speed of light c tends to infinity for all ***,we obtain rigorously an asymptotic estimate of the difference between the two systems.

关键词： Vlasov-Darwin system generalized variables global classical solution classical limit

An Optical Fiber Sensor for Simultaneous Measurement of pO₂ and pH

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Open Journal of Applied Sciences 2023年第4期13卷 579-590页

作者： Baorong Fu xianwen zhang Huimin Cao Zhushanying zhang Wuhan Great Sea Hi-Tech Co. Ltd Wuhan China Linyi Grepo Garden Machinery CO. LTD Linyi China College of Biomedical Engineering South-Central MinZu University Wuhan China

Whether in the monitoring of critically ill patients such as shock, respiratory failure, brain injury, or in major anesthesia surgeries, it is necessary to evaluate the patient’s pO2 and pH. An optical fiber sensor presented is capable of monitoring the presence of oxygen partial pressure (pO2) and pH in the real-time. The sensor is based on fluorescence sensing of polymer immobilized in the oxygen/pH-sensitive membranes and covalently attached to the optical fiber probe. The design of this sensor uses LED as light source, which is an excitation light source, inducing specific wavelengths of fluorescence on the oxygen/pH-sensitive membrane. The intensity and lifetime of fluorescence are related to the pO2 and pH. So the pO2 and pH can be measured by the relationship between the pO2/pH values and the intensity and lifetime of fluorescence. The signal conditioning system based on DSP and STM32 was used to store and process data, and display test values. The response of the sensor for pO2 and pH monitoring with nitrogen (N2) as a balancing gas in the laboratory was performed. Finally, the oxygen/pH sensing scheme presented in this work is intended for using in biological, medical and environmental applications.

关键词： Optical Fiber Sensor Oxygen pH Fluorescence