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1.
In this article we report on the experimental investigation of light storage for several types of diffractionfree beams (Bessel and Airy beams) and quasi-diffraction-free beams by utilizing electromagnetically induced transparency (EIT) technique in a hot atomic gas cell. The experimental results show that the diffraction-free and quasi-diffraction-free beams have better storage performances when compared with ordinary images possessing similar spatial profiles. Meanwhile, the Bessel beams and the quasidiffraction-free images are able to maintain their spatial profiles with a long storage time while the sidelobes of the Airy beam are gradually depleted with the increment of the storage time. We quantitatively analyze the storage results and give physical explanations behind these phenomena. Furthermore, the self-healing of the retrieved diffraction-free beams is verified, signifying that their characteristics preserve well after storage.  相似文献   
2.
Du  Tingchen  Geng  Haipeng  Wang  Bo  Lin  Hao  Yu  Lie 《Nonlinear dynamics》2022,109(4):2499-2523
Nonlinear Dynamics - A time-delayed proportional–derivative controller is applied to suppress the nonlinear vibration of a rigid rotor suspended by the active magnetic bearing (AMB) subjected...  相似文献   
3.
Antiperovskite Co3InC0.7N0.3 nanomaterials with highly enhanced oxygen reduction reaction (ORR) performance were prepared by tuning nitrogen contents through a metal–organic framework (MOF)‐derived strategy. The nanomaterial surpasses all reported noble‐metal‐free antiperovskites and even most perovskites in terms of onset potential (0.957 V at J=0.1 mA cm?2) and half‐wave potential (0.854 V). The OER and zinc–air battery performance demonstrate its multifunctional oxygen catalytic activities. DFT calculation was performed and for the first time, a 4 e? dissociative ORR pathway on (200) facets of antiperovskite was revealed. Free energy studies showed that nitrogen substitution could strengthen the OH desorption as well as hydrogenation that accounts for the enhanced ORR performance. This work expands the scope for material design via tailoring the nitrogen contents for optimal reaction free energy and hence performance of the antiperovskite system.  相似文献   
4.
通过使用不同相变温度的磷脂分子并调节二者的比例构筑了不同相态的磷脂膜, 并利用表面增强红外光谱和激光共聚焦显微镜研究了磷脂膜的相行为对氧化石墨烯和磷脂膜相互作用的影响. 结果表明, 氧化石墨烯对磷脂膜中磷脂分子的抽提作用具有显著的相态选择性, 其选择性地抽提流动相的磷脂分子; 氧化石墨烯对流动相磷脂的抽提作用受到膜中凝胶相磷脂存在比例的影响, 只有在流动相磷脂分子占磷脂膜中磷脂分子的绝大部分时才能够发生抽提作用, 且只有流动相的磷脂分子被抽提.  相似文献   
5.
Neural interface is a critical component for the communication between the central nervous system and outside devices. But neural tissues withstand constant mechanical activity with outside devices which aggravates inflammation response. The investigation about soft interfacial modification materials for neural implants is a promising way to reduce the mechanical mismatch of neural tissues and implants. In this study, soft alginic acid gel and poly(3, 4-ethylenedioxythiophene)/poly(styrene sulfate)(PEDOT/PSS) coated multi-walled carbon nanotubes(MWCNT) was co-deposited on a microwire neural electrode, then PEDOT/PSS was electrochemically grown through the coating material to form a kind of soft interpenetrating networks (IPNs) for the improvement of neural interface. Compared to unmodified electrodes, the modified electrodes possess higher charge storage capacity (CSC) and lower electrochemical impedance, which would benefit the performance of stimulating and recording respectively. The IPNs are very soft after reswelling in brain tissue, and the cell experiment indicate its fantastic biocompatibility. Furthermore, acute neural recording experiments revealed that the IPNs reduced the noise floor. All these characteristics are greatly desired for the neural interface. Overall, we developed a soft interpenetrating conducting hydrogel coating material on the neural interface with excellent electrical and biological performance.  相似文献   
6.
近年来,水分解、氧气/二氧化碳还原等电化学能源转换技术为解决全球能源短缺及环境问题提供了新的思路和方向.然而,对这些能源转换技术的反应机理及其催化剂的活性位点目前仍缺乏深刻的认识和理解,这限制了高效、稳定催化剂的开发,以致阻碍该类电化学技术的进一步发展.原位光谱技术的快速发展为解决上述问题提供了坚实的基础,其中拉曼光谱是检测含氧物种的有效技术,X射线吸收谱则是揭示催化剂配位环境和价态变化的有力工具.鉴于此,本文详细介绍了原位拉曼光谱和X射线吸收光谱在电化学领域的最新应用.重点分析了一些代表性的例子,主要包括:(1)揭示了不同Pt单晶以及Pt基催化剂表面的具体氧还原路径;(2)明确了过渡金属-氮-碳催化剂的真实氧还原位点;(3)解析了碱性条件下OH?离子对于氢氧化反应的作用;(4)揭示了氢析出反应中非Pt催化剂的活性位点;(5)检测到了氧析出和二氧化碳还原过程中催化剂的相变过程.上述例子表明原位表征技术的确可以有效监测电化学催化过程,捕捉中间产物,揭示反应机理以及表征催化剂的相变过程,可为合理的设计和制备高效催化剂提供可靠依据.然而,目前的原位表征技术还存在较多问题,比如拉曼光谱往往需要借助增强基底来增强其信号,从而限制其在表征实际催化剂中应用.而基于同步辐射光源的X射线吸收光谱其能量较高,可能会引发催化剂发生相变甚至损坏催化剂,而且它是一种体相敏感的表征技术,很难精确反映催化剂表面过程.除了这些原位技术的本身局限性之外,仍有许多问题阻碍对电催化过程的深入认识.例如,应将原位研究转化为工况研究,尤其要考虑电解质的作用.另外,缺乏有效的时间分辨技术来揭示不同电位下活性物种的动态变化.因此,需要不断发展新技术以及新策略,使得表征技术可以更精确真实地揭示电催化的原位过程,更有效地指导催化剂的设计开发.  相似文献   
7.
The direct growth of CdS nanocrystals in functional solid‐state thermotropic liquid crystal (LC) small molecules and a conjugated LC polymer by in situ thermal decomposition of a single‐source cadmium xanthate precursor to fabricate LC/CdS hybrid nanocomposites is described. The influence of thermal annealing temperature of the LC/CdS precursors upon the nanomorphology, photophysics, and optoelectronic properties of the LC/CdS nanocomposites is systematically studied. Steady‐state PL and ultrafast emission dynamics studies show that the charge‐transfer rates are strongly dependent on the thermal annealing temperature. Notably, annealing at liquid‐crystal state temperature promotes a more organized nanomorphology of the LC/CdS nanocomposites with improved photophysics and optoelectronic properties. The results confirm that thermotropic LCs can be ideal candidates as organization templates for the control of organic/inorganic hybrid nanocomposites at the nanoscale level. The results also demonstrate that in situ growth of semiconducting nanocrystals in thermotropic LCs is a versatile route to hybrid organic/inorganic nanocomposites and optoelectronic devices.  相似文献   
8.
A heterostructured semiconductor–metal ZnO?Ag nanoparticle (NP) composite was constructed through a straightforward photocatalytic strategy by using UV irradiation of ZnO NPs and an aqueous solution of Ag precursor. The ZnO?Ag NP composites serve as an effective cathode‐modifying layer in polymer solar cells (PSCs) with increased short‐circuit current density owing to the light‐trapping effect, and improved optical and electrical conductivity properties compared with pure ZnO NPs. The Ag NPs, which are photodeposited in situ on ZnO NPs, can act as effective antennas for incident light to maximize light harvesting and minimize radiative decay or nonradiative losses, consequently resulting in the enhanced photogeneration of excitons in PSCs. Systematic photoelectron and ‐physical investigations confirm that heterostructured ZnO?Ag NPs can significantly improve charge separation, transport, and collection, as well as lower charge recombination at the cathode interface, leading to a 14.0 % improvement in air‐processed device power conversion efficiency. In addition, this processable, cost‐effective, and scalable approach is compatible with roll‐to‐roll manufacturing of large‐scale PSCs.  相似文献   
9.
We present the single-slit diffraction of the arbitrary vector fields with different parameters m, n, and φ0theoretically and experimentally. The single slit covers the polarization singularity in the center and therefore the influence of the polarization singularity on the diffraction fringes is analyzed. The experimental results which agree well with the simulation results show that the total intensity of the diffraction field is related only to the topological charge m, but the polarization distribution of the diffraction field is related to all the parameters m, n, and φ0. Therefore, the diffraction patterns allow to determine all the parameters of the arbitrary vector fields.  相似文献   
10.
赵起  徐启福  刘列 《光学技术》2013,39(1):37-40
利用Mach-Zehnder干涉仪测量了空气开关中等离子体电子密度分布,使用高速分幅相机拍摄记录不同时延下的干涉条纹图像。针对实验获得的干涉条纹图像的特点,提出了一种首先进行频域FFT滤波去噪,然后进行空域二值化、细化的处理方法。该方法能够很好的消除图像噪声的影响,提取出单像素的亮条纹中心线,从而能够准确读取条纹坐标信息,再通过对干涉条纹偏移量进行Abel逆变换,得到等离子体电子密度分布。  相似文献   
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