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Pollen Morphology of the Platycodonoid Group (Campanulaceae ***.) and Its Systematic Implications

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Journal of Integrative Plant Biology 2012年第10期54卷 773-789页

作者： HONG De-Yuan pan kai-Yu State Key Laboratory of Systematic&Evolutionary Botany Institute of BotanyThe Chinese Academy of SciencesChina

In this study, we examined the pollen morphology of the platycodonoid group in Campanulaceae s. str. using a scanning electronic microscope. We used pollen grains of 25 accessions representing 24 species of the Codonopsis complex （including Campanumoea, Cyclocodon, Leptocodon, and all three subgenera of Codonopsis）, which is extremely controversial among authors for taxonomic treatment. Pollen morphology of all the other genera in the group observed by previous authors is taken into account in our discussion. A total of nine pollen types with two subtypes in the group were recognized and named for the first time. Molecular and morphological data imply that each pollen type corresponds to a natural group at generic level, and thus the mergence of Leptocodon with Codonopsis and the restoration of Cyclocodon as a separate genus are justifiable, and Codonopsis subg. Pseudocodonopsis, subg. Obconicicapsula, and two species of Codonopsis subg. Codonopsis （C. purpurea and C. chimiliensis） may be better classified as three independent genera separate from the core Codonopsis.

关键词： Campanulaceae s. str. platycodonoid group Codonopsis complex pollen morphology pollen type taxonomy systematics.

Electrospinning Janus Type CoO_(x)/C Nanofibers as Electrocatalysts for Oxygen Reduction Reaction

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Advanced Fiber Materials 2020年第2期2卷 85-92页

作者： Xueyuan Cao Jianping Deng kai pan State Key Laboratory of Organic‑Inorganic Composites Beijing Key Laboratory of Advanced Functional Polymer CompositesCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China

Nanofibers with unique structures and multiple components have attracted more and more attention,which could combine multi-functions in one ***-type biphasic nanofibers with unique structure can be quickly obtained by electrospinning *** produced CoO_(x)/C nanofibers with Janus structure by self-made side-by-side electrospinning spinneret,combined with electrospinning technology and heat ***_(x)/C nanofibers had a large amount of graphitic carbon distributed on one half of the Janus nanofiber,and CoO_(x)/C nanoparticles were embedded in the other half of the Janus nanofiber and distributed ***_(x)/C acted as ORR catalysis,and graphitic carbon,pridinc-N and CoO_(x) in CoO_(x)/C had a synergistic effect on their catalytic *** results confirmed that CoO_(x)/C was dominated by four-electron pathway under alkaline conditions,and the Tafel slope was lower than that of commercial Pt/C *** preparation method of this work is simple and easy,the structure is controllable,and the composition is adjustable,which provides a feasible way for preparing Janus structure nanofibers with different functions.

关键词： Janus nanofibers Electrospinning Electrocatalyst Oxygen reduction reaction

An unconventional phase field modeling of domains formation and evolution in tetragonal ferroelectrics

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Science China(Technological Sciences) 2016年第7期59卷 1059-1064页

作者： ZHOU YouGang PENG JinLin pan kai LIU YunYa Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education and Key Laboratory of Materials Design and Preparation Technology of Hunan Province School of Materials Science and Engineering Xiangtan University

Based on characteristic functions of variants, we developed an unconventional phase field modeling for investigating domains formation and evolution in tetragonal ferroelectrics. In order to develop this computational approach, we constructed the anisotropy energy of tetragonal variants, which is used instead of Landau-Devonshire potential in the conventional phase field method, resulting in that much fewer parameters are needed for simulations. This approach is advantageous in simulations of emerging ferroelectric materials. We employ it to study the formation and evolution of domains in tetragonal barium titanate single crystal, as well as the nonlinear behaviors under cyclical stress and electric field loading. A multi-rank laminated ferroelectric domain pattern, 90° domain switching accompanied by polarization rotation, and 180° domain switching accompanied by move of domain wall are predicted. It is found that the speed of 90° domain switching is slower than that of 180° domain switching, due to both polarization and transformation strain changed in 90° domain switching. It also suggests that large strain actuation can be generated in single crystal ferroelectrics via combined electromechanical loading inducing 90° domain switching. The good agreement between simulation results and experimental measurements is observed.

关键词： phase field simulation ferroelectric domains formation and evolution ferroelectric materials

One-dimension carbon self-doping g-C3N4 nanotubes： Synthesis and application in dye-sensitized solar cells

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Nano Research 2018年第3期11卷 1322-1330页

作者： Xue Li kai pan Yang Qu Guofeng Wang Key Laboratory of Functional Inorganic Material Chemistry Ministry of Education School of Chemistry and Materials Science Heilongjiang University Harbin 150080 China

One-dimensional carbon self-doping g-C3N4 nanotubes （CNT） with abundant communicating pores were synthesized via thermal polymerization of saturated or supersaturated urea inside the framework of a melamine sponge for the first time. A - 16% improvement in photoelectric conversion efficiency （η） is observed for the devices fabricated with a binary hybrid composite of the obtained CNT and TiO2 compared to pure TiO2 device. The result of EIS analysis reveals that the interfacial resistance of the TiO2-dye｜ I3^-/I- electrolyte interface of TiO2-CNT composite cell is much lower than that of pure TiO2 cell. In addition, the TiOa-CNT composite cell exhibits longer electron recombination time, shorter electron transport time, and higher charge collection efficiency than those of pure TiO2 cell. Systematic investigations reveal that the CNT boosts the light harvesting ability of the photovoltaic devices by enhancing not only the visible light absorption but also the charge separation and transfer.

关键词： g-C3N4 nanotube photoelectric conversion solar cells

Confinement and antenna effect for ultrasmall Y_(2)O_(3):Eu^(3+) nanocrystals supported by MOF with enhanced near-UV light absorption thereby enhanced luminescence and excellently multifunctional applications

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Nano Research 2021年第3期14卷 720-729页

作者： Hongyi Xu Wenjing Yu kai pan Guofeng Wang Peifen Zhu Key Laboratory of Functional Inorganic Material Chemistry Ministry of EducationSchool of Chemistry and Materials ScienceHeilongjiang UniversityHarbin150080China Department of Physics and Engineering Physics The University of TulsaTulsaOK74104USA

A novel host-guest luminous system with enhanced near-UV light absorption thereby enhanced luminescence are designed based on the synergism of quantum confinement,spatial confinement,and antenna effect,where ultrasmall Y_(2)O_(3):Eu^(3+)nanocrystals are fixed inside MOF(Eu/Y-BTC)as supporting *** Eu/Y-BTC not only limits the size and leads to lattice distortion of Y_(2)O_(3):Eu^(3+)nanocrystals and controls the distance between nanocrystals,but also promotes the light absorption and *** significantly red-shifted and broadened charge transfer band of Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)leads to the excellent applications of Y_(2)O_(3):Eu^(3+)in white light-emitting diodes(LEDs).Our results show that white light with superior color quality(CRI>90)and extremely high luminous efficacy(an LER of 335 lm/W)could be achieved using Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)as red *** Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)also improves the photoelectric performance of dye-sensitized solar cells(DSSCs),not only because Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)has a large specific surface area and the adsorption amount of the dye is increased,but also because the valence band position of Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)is 2.41 eV,which can provide an additional energy level between the TiO2 and dye,promoting electron *** these advantageous features,the multifunctional Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)composite product will open new avenues in white LEDs and DSSCs.

关键词： confinement effect antenna effect enhanced luminescence ultrasmall Y_(2)O_(3):Eu^(3+)nanocrystals MOFs multifunctional applications

Little for more: An Active Discovery Strategy for Content Routing in ICN

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China Communications 2016年第S1期13卷 54-64页

作者： pan kai LI Hui LIU Weiyang LI Dagang Shenzhen Key Lab of Information Theory & Future Internet Architecture Shenzhen Engineering Lab of Converged Networks TechnologyInstitution of Big Data Technology Peking University SPCCTA Peking University Shenzhen Graduate School

While receiving a certain packet with unknown destination, a router either simply drops it or sends queries around as a *** it sacrifices transmission stability, but sending queries may cause too much *** situation can be seen more frequently in Information-Centric Networking(ICN) since it has a larger namespace for routing *** this paper, we propose the neighboring chunk aware discovery(NCAD), an active discovery strategy for content routing. NCAD can reduce the cost of resolving unknown contents, which is not yet considered by the conventional routing mechanism. The idea behind NCAD is to ask the nodes to report back more possession information about the queried content in prediction of later use. To this end, we de-sign NCAD with several different considerations,and balance the tradeoff between effectiveness in conjunction with the overhead to achieve optima on the whole. Extensive experiments are conducted on a small typical topology and a large real-world Internet AS-level *** results show an overall superiority of NCAD in terms of both effectiveness and overhead.

关键词： prevailing approach active discovery strategy neighboring chunk alternative tradeoff

Interface flux reconstruction method based on optimized weight essentially non-oscillatory scheme

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Chinese Journal of Aeronautics 2018年第5期31卷 1020-1029页

作者： Peixun YU Junqiang BAI Hai YANG Song CHEN kai pan Northwestern Polytechnical University Xi'an 710072 China Aircraft Strength Research Institute of China Laboratory of Aeronautical Acoustics and Dynamics Xi'an 710065 China Hubei Space Aircraft Research Institute Wuhan 430040 China

Aimed at the computational aeroacoustics multi-scale problem of complex configurations discretized with multi-size mesh, the flux reconstruction method based on modified Weight Essentially Non-Oscillatory（WENO） scheme is proposed at the interfaces of multi-block *** the idea of Dispersion-Relation-Preserving（DRP） scheme, different weight coefficients are obtained by optimization, so that it is in WENO schemes with various characteristics of dispersion and dissipation. On the basis, hybrid flux vector splitting method is utilized to intelligently judge the amplitude of the gap between grid interfaces. After the simulation and analysis of 1D convection equation with different initial conditions, modified WENO scheme is proved to be able to independently distinguish the gap amplitude and generate corresponding dissipation according to the grid resolution. Using the idea of flux reconstruction at grid interfaces, modified WENO scheme with increasing dissipation is applied at grid points, while DRP scheme with low dispersion and dissipation is applied at the inner part of grids. Moreover, Gauss impulse spread and periodic point sound source flow among three cylinders with multi-scale grids are carried out. The results show that the flux reconstruction method at grid interfaces is capable of dealing with Computational Aero Acoustics（CAA） multi-scale problems.

关键词： Computational aeroacousties Dispersion-Relation-Preserving (DRP) scheme Flux reconstruction Modified Weight Essentially Non-Oscillatory (WENO)scheme Multi-size mesh

Synthesis of pure phase Mg1.2Ti1.8O5 and MgTiO3 nanocrystals for photocatalytic hydrogen production

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Nano Research 2016年第3期9卷 726-734页

作者： Ning Zhang Yang Qu kai pan Guofeng Wang Yadong Li Key Laboratory of Functional Inorganic Material Chemistry Ministry of Education School of Chemistry and Materials Science Heilongjiang University Harbin 150080 China Department of Chemistry Tsinghua University Beijing 100084 China

Synthesis of pure phase Mg1.2Ti1.8O5 and MgTiO3 nanocrystals has proven to be challenging. Here, pure phase Mg1.2Ti1.8O5 and MgTiO3 nanocrystals were prepared. Furthermore, a new magnesium titanate, Mg1.2Ti1.8O5, was synthesized via a solution-based route for the first time. As hydrogen evolution photocatalysts, both pure phase Mg1.2TiLsO5 and MgTiO3 nanocrystals exhibit excellent hydrogen production efficiency. In comparison with pure MgTiO3 nanocrystals, the asprepared Mg1.2Ti1.8O5 nanocrystals exhibited four times as much photocatalytic hydrogen production activity, up to 40 μmol.h-1 Photoelectrochemical analysis, including linear sweep voltammetry, transient photocurrent measurement, electrochemical impedance spectroscopy, and construction of Mott-Schottky plots, demonstrated that the enhanced photocatalytic activity was attributed to the large surface area, fast photoelectron transfer, higher carrier density, and efficient charge separation of the Mg1.2Ti1.8O5 nanocrystals.

关键词： Mg1.2Ti1.8O5 MgTiO3 nanocrystals photocatalytic hydrogenproduction

Multi‑color Tunable and White Circularly Polarized Luminescent Composite Nanofibers Electrospun from Chiral Helical Polymer

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Advanced Fiber Materials 2022年第6期4卷 1632-1644页

作者： Pengpeng Li Xiaobin Gao Biao Zhao kai pan Jianping Deng State Key Laboratory of Chemical Resource Engineering College of Materials Science and EngineeringBeijing University of Chemical Technology100029 BeijingChina College of Materials Science and Engineering Beijing University of Chemical Technology100029 BeijingChina

Circularly polarized luminescence(CPL)-active nanomaterials have attracted tremendous ***,it is still a big challenge to conveniently fabricate multi-color and white CPL-active nanomaterials on a large ***,a simple and scalable approach to achieve the above goals is *** CPL-active nanofibers are fabricated from chiral helical substituted polyacetylene,achiral fluorescent dyes and polyacrylonitrile via uniaxial electrospinning;the highest luminescence dissymmetry factor(glum)of the resulting nanofibers can reach 10^(−2).Furthermore,white CPL-active nanofibers are obtained by coaxial electrospinning,in which the resulting core-shell structure has excellent adjustability and can be utilized to physically isolate different fluorescent dyes to reduce energy transfer efficiency;therefore,stable white CPL emissions can be achieved with high g_(lum) values up to 10^(−3).Notably,the prepared white-emission CPL nanofibrous films show bright white circularly polarized light when coated on UV chips,demonstrating their future application in constructing low-cost and flexible light-emitting devices such as circularly polarized light-emitting diodes.

关键词： Chiral helical polymer Nanofiber Multi-color circularly polarized luminescence White-light emission