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Structure and electrochemical properties of La, F dual-doped liLa_(0.01)Mn_(1.99)O_(3.99)F_(0.01) cathode materials

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Journal of University of Science and Technology Beijing 2008年第4期15卷 468-473页

作者： Meng Chen Shengjun li chuang Yang College of Material Science and Chemical Engineering Harbin Engineering University Harbin 150001 China

The cathode materials liMn2O4 and rare earth elements La-doped or La and F dual-doped spinel lithium manganese *** synthesized by the citric acid-assisted sol-gel method. The synthesized samples were investigated by differential thermal analysis （DTA） and thermogravimetry （TG） measurements, X-ray diffraction （XRD）, scanning electronic microscope （SEM）, cyclic voltammetry （CV）, and charge-discharge test. XRD data shows that all the samples exhibit the same pure spinel phase, and the liLa0.01Mn1.99O3.99F0.01 and ***.9904 samples have smaller lattice parameters and unit cell volume than liMn2O4. SEM indicates that liLa0.01Mn1.99O3.99F0.01 has a slightly smaller particle size and a more regular morphology structure with narrow size distribution. The charge-discharge test reveals that the initial capacities of liMn2O4, liLa0.01Mn1.99O4, and liLa0.01Mn1.99O3.99F0.01 are 129.9, 122.8, and 126.4 mAh·g^-1, and the capacity losses of the initial values after 50 cycles are 14.5%, 7.6%, and 8.0%, respectively The CVs show that the La and F dual-doped spinel displays a better reversibility than liMn2O4.

关键词： lithium ion battery cathode material liMn2O4 structure electrochemical properties

Photoswitchable Spiropyridine Enabled Photoactuation of Polymeric Hydrogels under Physiological pH Conditions

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Chinese Journal of Polymer Science 2024年第10期42卷 1602-1609,I0015页

作者： Cong liao Meng-Qi Du chuang li Key Laboratory of Precision and Intelligent Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaAnhui230026China

The incorporation of molecular switches into polymer networks has been a powerful approach for the development of functional polymer materials that display macroscopic actuation and function enabled directly by molecular ***,such materials sometimes require harsh conditions to perform their functions,and the design of new molecular photoswitches that can function under physiological conditions is highly ***,we report the design and synthesis of a spiropyridine-based photoswitchable hydrogel that exhibits light-driven actuation at physiological *** to its high p Ka,spiropyridine maintains its ring-open protonated form at neutral pH,and the resulting hydrogel remains in a swollen *** irradiation with visible light,the ring closure of spiropyridine leads to a decrease in the charge and a reduction in the volume of the *** contracted gel could spontaneously recover to its expanding state in the dark,and this process is highly dynamic and reversible when the light is switched on and ***,the hydrogel shows switchable fluorescence in response to visible *** deformation is observed in the hydrogel thin films upon irradiation from one ***,the independence of this spiropyridine hydrogel from the acidic environment makes it biotolerant and shows excellent *** biocompatible spiropyridine hydrogel might have important biorelated applications in the future.

关键词： Spiropyridine photowitch Polymer hydrogel Photoactuation Physiological pH Biocompatibility

Reveal the nematic topological superconductivity from the anisotropic unconventional Josephson effect:Theory and application to doped Bi_(2)Se_(3)

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Science China(Physics,Mechanics & Astronomy) 2021年第9期64卷 112-122页

作者： Han-Bing Leng chuang li Xin liu School of Physics and Institute of Quantum Science and Engineering Huazhong University of Science and TechnologyWuhan 430074China Wuhan National High Magnetic Field Center and Hubei Key Laboratory of Gravitation and Quantum Physics Wuhan 430074China

We propose a scheme to reveal the possible nematic superconducting order parameter in the doped Bi2Se3 by observing the anisotropic unconventional Josephson effect without an external magnetic *** find the presence of an intrinsicπ-phase in the spin-triplet channel of Andreev *** competition with the odd-parity superconducting gap phase can lead to unconventional Josephson effect in the Josephson junction,whose normal region is connected to the same side of the superconductor,called the U-shaped junction according to its *** Josephson junctions with the interfaces perpendicular to the nematic direction,the competition will lead to a Josephsonπ-*** the case where the interface is parallel to the nematic direction,it will lead to a Josephson ***,this can directly reflect the nematic *** is worth noting that Josephson coupling with the 4πperiod appears only in the normal injected ***,if the Josephson junction adopts a conventional geometry,it always exhibits a normal Josephson 0-junction regardless of the gap function taken by the doped Bi2Se3 and therefore cannot distinguish the pairing *** thus propose a superconducting quantum interference device containing a U-shaped Josephson junction to detect nematic *** proposal not only can be applied to detect nematic superconductivity but also provides a feasible platform for topological quantum computation.

关键词： topological superconductors spin-triplet pairings odd parity unconventional Josephson effect

The Infiltration Process and Texture Transition of 2D C/C Composites

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Journal of Materials Science & Technology 2009年第1期25卷 109-114页

作者： Hejun li Guozhong Xu Kezhi li chuang Wang Wei li Miaoling li Carbon/carbon Composites Research Center Key Laboratory of Ultrahigh Temperature Composites Northwestern Polytechnical University Xi＇an 710072 China

2D needle-punched fiber felt was infiltrated by a kind of rapid isothermal chemical vapor infiltration technique. The infiltration process and texture transition of the infiltrated C/C composites were investigated. The porosity and the variations of the cumulative pore volume were determined by mercury porosimetry. The texture of matrix carbon was studied under a polarized light microscope. The results show that the relative mass gain of the sample increases directly as the infiltration time at the initial stage until 20 h, and subsequently the increasing rate of the relative mass gain decreases gradually with the prolonging of infiltration time. Three layers of pyrocarbon were formed around fibers. Low-textured pyrocarbon was obtained at the initial stage. With the densification going on, high-textured pyrocarbon was formed on the surface of low-textured pyrocarbon. Then, low-textured pyrocarbon was produced again during the final stage of densification. The texture transition is ascribed to the variation of the ratio of cumulative inner surface area to volume of pores and the gas partial pressure in pores.

关键词： C/C composites Isothermal chemical vapor infiltration (ICVI) Pyrocarbon Mercury porosimetry Polarized light microscope

Study on the Electromagnetic Interference of CFRC Composites by Reflectivity

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Journal of Materials Science & Technology 2008年第2期24卷 265-271页

作者： Kezhi li chuang WANG Hejun li Gengsheng JIAO Jian WEI School of Materials Science and Engineering Northwestern Polytechnical University Xi＇an 710072 China

The influence of dispersion of carbon fibers in carbon-fiber-reinforced cement-based composites （CFRC） on the mechanical properties of the composites was discussed. The microstructure of the fracture surface of the CFRC samples was observed with a scanning electron microscope （SEM）. The electromagnetic interference （EMI） was evaluated indirectly by reflectivity in the Naval Research Laboratory （NRL） testing system. The reflectivity of the electromagnetic radiation by the composites was measured in the frequency range of 8.0- 18.2 GHz for different carbon fiber contents of 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% （in wt pct）, respectively. The results showed that the reflectivity decreased with the growing fiber content till the percentage of 0.6%. The minimum reflectivity was -23 dB, far less than -10 dB, and the composites were strong wave absorbers. After this percentage, the curve increased abruptly as the fiber content proceeded. The electromagnetic waves were gradually reflected. When the fiber content reached 1.0% finally, the maximum reflectivity -7.5 dB appeared and there was stronger reflection. The shielding mechanism includes mainly reflection, absorption, and multiple reflections.

关键词： Carbon fibers Cement-based Electromagnetic interference Reflectivity

Plane-Wave Least-Squares Reverse Time Migration for Rugged Topography

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Journal of Earth Science 2015年第4期26卷 471-480页

作者： Jianping Huang chuang li Rongrong Wang Qingyang li School of Geosciences China University of Petroleum (East China) College of Information and Control Engineering China University of Petroleum (East China)

We present a method based on least-squares reverse time migration with plane-wave encoding （P-LSRTM） for rugged topography. Instead of modifying the wave field before migration, we modify the plane-wave encoding function and fill constant velocity to the area above rugged topography in the model so that P-LSRTM can be directly performed from rugged surface in the way same to shot domain reverse time migration. In order to improve efficiency and reduce I/O （input/output） cost, the dynamic en- coding strategy and hybrid encoding strategy are implemented. Numerical test on SEG rugged topography model show that P-LSRTM can suppress migration artifacts in the migration image, and compensate am- plitude in the middle-deep part efficiently. Without data correction, P-LSRTM can produce a satisfying image of near-surface if we could get an accurate near-surface velocity model. Moreover, the pre-stack P- LSRTM is more robust than conventional RTM in the presence of migration velocity errors.

关键词： least-squares migration rugged topography plane-wave encoding dynamic encoding hybrid encoding.

Effect of chemical vapor infiltration treatment on the wave-absorbing performance of carbon fiber/cement composites

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Journal of University of Science and Technology Beijing 2008年第6期15卷 808-815页

作者： Kezhi li chuang Wang Hejun li lingjun Guo Jihua Lu School of Materials Science Northwestern Polytechnical University Xi＇an 710072 China

Short carbon fibers were treated at high temperatures around 1100℃ through chemical vapor infiltration technology. A thinner layer ofpyrocarbon was deposited on the fiber surface. The dispersion of carbon fibers in a cement matrix and the mechanical properties of carbon fiber/cement composites were investigated by scanning electron microscopy （SEM） and other tests. The reflec- tivity of electromagnetic waves by the composites was measured in the frequency range of 8.0-18 GHz for different carbon fiber contents of 0.2wt%, 0.4wt%, 0.6wt%, and 1.0wt%. The results show that the reflectivity tends to increase with the increase of fiber content above 0.4wt%. The minimum reflectivity is -19.3 dB and the composites exhibit wave-absorbing performances. After pyrocarbon is deposited on the fiber, all the refiectivity data are far greater. They are all above -10 dB and display mainly wave-reflecting performances.

关键词： carbon fibers chemical vapor infiltration cement reflectivity wave-absorbing property

Preparation and Characterization of Buoyant Nitrogen-doped TiO_2 Composites Supported by Fly Ash Cenospheres for Photocatalytic Applications

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Journal of Materials Science & Technology 2013年第9期29卷 835-840页

作者： chuang li Bing Wang Hao Cui Jianping Zhai Qin li State Key Laboratory of Pollution Control and Resource Reuse and School of the EnvironmentNanjing University

Fly ash cenospheres （FACs） coated with nitrogen-doped Ti02 （N-TiO2） composites were prepared by the sol-gel method for use as photocatalysts. The photocatalytic activity and kinetics of the composites produced at different calcination temperatures and with different nitrogen doping contents were studied under visible light irradiation by monitoring the environmental degradation of methylene blue （MB）. The MB degradation ratio of N-TiO2/FAC （25%, 450 ~C） was 10% higher than that of N-TiO2 and 40% higher than that of TiO2/FAC. These N-TJO2/FAC composites floated in water and could be recovered after the photocatalytic reaction by phase separation.

关键词： Nitrogen Photocatalyst Sol-gel core--shell particle Composite

Packet-loss-dependent stabilization of NCSs with network-induced delay and packet dropout

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Journal of Systems Engineering and Electronics 2012年第3期23卷 408-413页

作者： Yan Song Jingcheng Wang Yuanhao Shi chuang li Key Laboratory of System Control and Information Processing Ministry of Education of China Department of Automation Shanghai Jiao Tong University Shanghai 200240 P. R. China

This paper is concerned with controller design of net- worked control systems （NCSs） with both network-induced delay and arbitrary packet dropout. By using a packet-loss-dependent Lyapunov function, sufficient conditions for state/output feedback stabilization and corresponding control laws are derived via a switched system approach. Different from the existing results, the proposed stabilizing controllers design is dependent on the packet loss occurring in the last two transmission intervals due to the network-induced delay. The cone complementary lineara- tion （CCL） methodology is used to solve the non-convex feasibility problem by formulating it into an optimization problem subject to linear matrix inequality （LMI） constraints. Numerical examples and simulations are worked out to demonstrate the effectiveness and validity of the proposed techniques.

关键词： networked control systems (NCSs) network-induced delay packet dropout packet-loss-dependent cone complemen- tary linearation (CCL).