磁性量子元胞自动机功能阵列的实验研究

采用电子束光刻、热蒸镀和剥离工艺在室温下制备了多组磁性量子元胞自动机器件功能阵列. 实验研究了曝光剂量和曝光时间对三个不同间距参数磁性量子元胞自动机阵列图案的影响, 发现100 pA电子束束流和0.38 μs曝光时间可获得理想的阵列图案. 对制备的反相器阵列结构进行了磁力显微测试, 结果显示了正确的逻辑功能, 成功实现了不同间距参数功能阵列的实验制备. 此外, 实验还发现纳磁体阵列制备中容易出现缺陷, 模拟结果表明丢失纳磁体缺陷导致了信号传递反相.     

Sensitive detection of DNA based on the optical properties of core–shell gold nanorods

In this article, a type of core–shell nanostructure, Au₂S/AuAgS/Ag₃AuS₂-coated gold nanorods (GNRs) with unique optical properties was used as a sensing platform to detect fish sperm DNA (fsDNA). The prepared core–shell nanorods are positively charged due to the adsorption of the positively charged cetyltrimethylammonium bromide (CTAB) cations on their surface. fsDNA can form ternary fsDNA–CTAB–nanorod complexes together with CTAB and nanorod, which provides a useful platform to detect fsDNA through absorption spectra and resonance light scattering (RLS) spectroscopy. In this sensitive core–shell nanorod sensor, CTAB concentration and the nanoparticle dosage play important roles and have been investigated. Moreover, the fsDNA–CTAB–nanorod complexes induce a great enhancement of RLS intensity of the core–shell GNRs and directly proportional to the concentration of fsDNA, reaching a detection limit of about 10⁻⁹ mg/mL. This study will be significant for as-prepared core–shell GNRs for future application in biological systems.     

Preparation and characterization of spinel Li4Ti5O12 nanoparticles anode materials for lithium ion battery

Spinel Li₄Ti₅O₁₂ nanoparticles were prepared via a high-temperature solid-state reaction by adding the prepared cellulose to an aqueous dispersion of lithium salts and titanium dioxide. The precursors of Li₄Ti₅O₁₂ were characterized by thermogravimetry and differential scanning calorimetry. The obtained Li₄Ti₅O₁₂ nanoparticles were characterized using X-ray diffraction, transmission electron microscopy (TEM) and electrochemical measurements. The TEM revealed that the Li₄Ti₅O₁₂ prepared with cellulose is composed of nanoparticles with an average particle diameter of 20–30 nm. Galvanostatic battery testing showed that nano-sized Li₄Ti₅O₁₂ exhibit better electrochemical properties than submicro-sized Li₄Ti₅O₁₂ do especially at high current rates, which can deliver a reversible discharge capacity of 131 mAh g⁻¹ at the rate of 10 C, whereas that of the submicro-sized sample decreases to 25 mAh g⁻¹ at the same rate (10 C). Its reversible capacity is maintained at ~172.2 mAh g⁻¹ with the voltage range 1.0–3.0 V (vs. Li) at the current rate of 0.5 C for over 80 cycles.     

A Pyrene-based Highly Selective Turn-on Fluorescent Sensor for Copper(II) Ion and its Application in Live Cell Imaging

A new pyrene derivative (chemosensor 1) containing a picolinohydrazide moiety exhibits high selectivity for Cu²⁺ ion detection in mixed aqueous media (CH₃OH:H₂O = 7:3). Significant fluorescence enhancement was observed with chemosensor 1 in the presence of Cu²⁺. However, the metal ions Ag⁺, Ca²⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe²⁺, Fe³⁺, Hg²⁺, K⁺, Mg²⁺, Mn²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ produced only minor changes in fluorescence for the system. The apparent association constant (K _a) of Cu²⁺ binding in chemosensor 1 was found to be 2.75*10³ M⁻¹. The maximum fluorescence enhancement caused by Cu²⁺ binding in chemosensor 1 was observed over the pH range 5–8. Moreover, by means of fluorescence microscopy experiments, it is demonstrated that 1 can be used as a fluorescent probe for detecting Cu²⁺ in living cells.     

Efficient top-emitting white organic light emitting device with an extremely stable chromaticity and viewing-angle

In this paper,we report on the fabrication of a top-emitting electrophosphorescent p-i-n white organic lightemitting diode on the basis of a low-reflectivity Sm/Ag semi-transparent cathode together with a thickness-optimized ZnS out-coupling layer.With a 24-nm out-coupling layer,the reflectivity of the cathode is reduced to 8% at 492 nm and the mean reflectivity is 24% in the visible area.By introducing an efficient electron blocking layer tris(1phenylpyrazolato,N,C2 ’)iridium(III)(Ir(ppz) 3) to confine the exciton recombination area,the current efficiency and the colour stability of the device are effectively improved.A white emission with the Ir(ppz) 3 layer exhibits a maximum current efficiency of 9.8 cd/A at 8 V,and the Commission Internationale de L’Eclairage(CIE) chromaticity coordinates are almost constant during a large voltage change of 6 V-11 V.There is almost no viewing angular dependence in the spectrum when the viewing angle is no more than 45,with a CIE x,y coordinate variation of only(±0.0025,±0.0008).Even at a large viewing angle(75),the CIE x,y coordinate change is as small as(±0.0087,±0.0013).     

X波段长脉冲同轴多注相对论速调管放大器的分析与设计

为了提高相对论速调管放大器的工作频率、输出功率以及转换效率, 结合三重轴相对论速调管和多注速调管的特点, 采用三维电磁粒子模拟软件分析与设计了工作在X波段的长脉冲同轴多注相对论速调管放大器, 通过优化设计有效地抑制了X波段长脉冲相对论速调管放大器的自激振荡, 避免了脉冲缩短现象的产生, 使X波段相对论速调管放大器在长脉冲状态下能够稳定工作, 在注入微波功率为70 kW、束压为600 kV、束流为5 kA、轴向引导磁感应强度为0.8 T的条件下, 输出微波功率达到了1.23 GW, 效率为41%, 增益为42 dB.     

十字环型左手材料单元结构设计与仿真

提出了一种新型十字环型左手材料结构单元.该结构只需在介质板单侧蚀刻, 即可在二维方向上产生等效负介电常数和等效负磁导率.通过理论分析, 提出场-路结合的等效源分析法以计算等效介电常数、磁导率, 并据此对十字环型结构单元的左手特性激发机理进行了论证. 后采用Nicolson-Ross-Weir 等效参数法提取了十字环型单元阵列的相对介电常数和相对磁导率, 并通过棱镜实验对材料的负折射特性进行了验证.实验表明, 该左手材料在6.8-6.9 GHz频段具有二维入射左手特性. 此种左手材料制作工艺相对简单, 为左手材料在微波器件领域的应用提供了一种较为实用的设计方案.     

基于Poincaré差值散点图的心率变异性分析方法研究

在心率变异性的非线性分析中, Poincaré散点图分析是一种重要手段.本文基于Poincaré差值散点图(modified Poincaré plot)提出了两个参数——区域分布熵和区域分布系数, 用于定量描述所考察区域内散点的分布趋势, 并提出对散点在4个象限中的分布进行分别计算.通过对MIT-BIH数据库中健康年轻人、健康老年人和充血性心力衰竭患者样本数据的分析, 发现两参数值均呈现显著的组间差异;同时, 不同象限的分析结果显示了四个象限具有不同的区分敏感性, 而其中尤以第一象限的区分度为最高, 反映出充血性心力衰竭患者相对健康人迷走神经调控功能的改变最为显著, 与以往的生理学研究结论相符.经验证, 该方法可用于短时数据, 更易于扩展至临床应用.     

Radiation characteristics and implosion dynamics of tungsten wire array Z-pinches on the YANG accelerator

We investigated the radiation characteristics and implosion dynamics of low-wire-number cylindrical tungsten wire array Z-pinches on the YANG accelerator with a peak current 0.8-1.1 MA and a rising time ～ 90 ns.The arrays are made up of(8-32)×5 μm wires 6/10 mm in diameter and 15 mm in height.The highest X-ray power obtained in the experiments was about 0.37 TW with the total radiation energy ～ 13 kJ and the energy conversion efficiency ～ 9%(24×5 μm wires,6 mm in diameter).Most of the X-ray emissions from tungsten Z-pinch plasmas were distributed in the spectral band of 100-600 eV,peaked at 250 and 375 eV.The dominant wavelengths of the wire ablation and the magneto-Rayleigh-Taylor instability were found and analyzed through measuring the time-gated self-emission and laser interferometric images.Through analyzing the implosion trajectories obtained by an optical streak camera,the run-in velocities of the Z-pinch plasmas at the end of the implosion phase were determined to be about(1.3-2.1)×10 7 cm/s.     

The effect of interfacial energy anisotropy on planar interface instability in a succinonitrile alloy under a small temperature gradient

The morphological stability of a planar interface with different crystallographic orientations is studied under a small positive temperature gradient using a transparent model alloy of succinonitrile.Novel experimental apparatus is constructed to provide a temperature gradient of about 0.37 K/mm.Under this small temperature gradient,the planar interface instability depends largely on the crystallographic orientation.It is shown experimentally that the effect of interfacial energy anisotropy on planar interface stability cannot be neglected even in a small temperature gradient system.Higher interfacial energy anisotropy leads the planar interface to become more unstable,which is different from the stabilizing effect of the interfacial energy on the planar interface.The experimental results are in agreement with previous theoretical calculations and phase field simulations.