Photonic bandgap via nonlinear modulation assisted by spontaneously generated coherence

A four-level double-ladder atomic system with two upper states coupled to the excited state by a standing-wave trigger field is explored to generate photonic bandgap (PBG) structure. With the assistance of spontaneously generated coherence (SGC) from the two decay pathways, we can obtain single or double fully developed PBG when the trigger field is far away from resonance or resonant. While in the absence of SGC, the atomic medium becomes strong absorptive to the probe field, and therefore the resulting PBGs are severely malformed or even cannot be opened up. Numerical results show that the PBG structure is originated from the third-order cross Kerr nonlinear modulation between the probe and trigger fields. This mechanism differs from the recent schemes based on linear modulation.     

Preparation of Highly Stable and Photoluminescent Cadmium-Free InP/GaP/ZnS Core/Shell Quantum Dots and Application to Quantitative Immunoassay

Indium phosphide (InP) quantum dots (QDs) are ideal substitutes for widely used cadmium-based QDs and have great application prospects in biological fields due to their environmentally benign properties and human safety. However, the synthesis of InP core/shell QDs with biocompatibility, high quantum yield (QY), uniform particle size, and high stability is still a challenging subject. Herein, high quality (QY up to 72%) thick shell InP/GaP/ZnS core/shell QDs (12.8 ± 1.4 nm) are synthesized using multiple injections of shell precursor and extension of shell growth time, with GaP serving as the intermediate layer and 1-octanethiol acting as the new S source. The thick shell InP/GaP/ZnS core/shell QDs still keep high QY and photostability after transfer into water. InP/GaP/ZnS core/shell QDs as fluorescence labels to establish QD-based fluorescence-linked immunosorbent assay (QD-FLISA) for quantitative detection of C-reactive protein (CRP), and a calibration curve is established between fluorescence intensity and CRP concentrations (range: 1–800 ng mL⁻¹, correlation coefficient: R² = 0.9992). The limit of detection is 2.9 ng mL⁻¹, which increases twofold compared to previously reported cadmium-free QD-based immunoassays. Thus, InP/GaP/ZnS core/shell QDs as a great promise fluorescence labeling material, provide a new route for cadmium-free sensitive and specific immunoassays in biomedical fields.     

频率选择表面天线罩研究现状与发展趋势

由于雷达天线系统自身工作的特点, 他必须保证自身雷达波的正常接收和发射, 常用的隐身措施无法简单地在雷达天线隐身中获得应用. 采用频率选择表面 (FSS) 技术与天线罩技术相结合形成FSS天线罩, 可以使天线罩获得频率选择的功能. 即FSS天线罩对雷达的工作频段提供带通的传输特性, 同时改变雷达工作频段以外的雷达散射截面 (RCS) 特性, 可以实现带外隐身. 本文分析了FSS天线罩制备的基本思路, 综述了国内外FSS天线罩在结构设计、制造工艺等方面的研究状况, 并从多频FSS天线罩、智能FSS天线罩、厚屏FSS天线罩、 微型化FSS天线罩以及各技术的组合等方面对FSS天线罩的发展进行了展望. 关键词： 频率选择表面(FSS) 多频FSS天线罩 智能FSS天线罩 厚屏FSS天线罩     

Gd替代对La0.6-xGdxSr1.4MnO4磁性和输运性质的影响

随着x的增加，多晶La0.6-xGdxSr1.4MnO4（x=0, 0.1, 0.2, 0.4, 0.6）的零场冷却 曲线从类自旋玻璃型转变成顺磁型，并且每条零场冷却 曲线都有一在20K的拐点。这一行为可以从Gd和Mn各自对材料总磁性的不同贡献来理解。另外，在所有的样品中，从100K到室温，都观察到了热激活导电行为。由于Mn-Mn间强的反铁磁耦和，直到外场达到50 kOe，都没有观察到明显的磁电阻效应。     

超强激光脉冲下等离子体块的整体加速研究

为了克服激光加速中强流离子束空间电荷效应对粒子输运的影响,提出一种利用两块不同密度的固体靶先后和一束强度约为1022 W/cm2、脉冲长度为5T(T为激光周期)的超强脉冲激光相互作用的方案,实现了中性等离子体块的加速。通过一维PIC数值模拟研究发现,在合适的参数下,加速后的电子与质子几乎以相同的速度共同飞行长达60λ(λ为激光波长)的距离,其中质子与电子的能量分别为GeV和100MeV量级。     

Synthesis and electrochemical properties of P2-Na<Subscript>2/3</Subscript>Ni<Subscript>1/3</Subscript>Mn<Subscript>2/3</Subscript>O<Subscript>2</Subscript>

The pure phase P2-Na_2/3Ni_1/3Mn_2/3O₂ was synthesized by a solid reaction process. The optimum calcination temperature was 850 °C. The as-prepared product delivered a capacity of 158 mAh g^?1 in the voltage range of 2–4.5 V, and there was a phase transition from P2 to O2 at about 4.2 V in the charge process. The P2 phase exhibited excellent intercalation behavior of Na ions. The reversible capacity is about 88.5 mAh g^?1 at 0.1 C in the voltage range of 2–4 V at room temperature. At an elevated temperature of 55 °C, it could remain as an excellent capacity retention at low current rates. The P2-Na_2/3Ni_1/3Mn_2/3O₂ is a potential cathode material for sodium-ion batteries.     

非线性Jaynes-Cummings模型中的薛定谔猫态

本文采用密度算符间的距离论证了非线性(强度相关)Jaynes-Cummings模型在初始相干光场很强的条件下光场周期地演化为薛定谔猫态,且薛定谔猫态的特性取决于原子的初态。     

Experimental Study of a High Power Coupler for a Tunable Cavity Formed by a Vane-Type Structure

In this study, a high power coupler designed for a tunable planar cavity is experimentally tested. The cavity consists of a periodical vane-type structure, of which the height of the vane can be mechanically adjusted so that the resonance frequency can be fine tuned. The cavity is designed to be operated at mode and resonant at 2.45 GHz. The high power coupler is composed of a rectangular waveguide and a cylindrical ceramic rod with tapered ends. One end of the ceramic rod is intruded into the gap between two vanes of the cavity. Through this coupler, the TE₁₀ mode of the rectangular waveguide is converted into the TE₁₁ mode of the ceramic rod and then couples to the TEM mode in the gap between vanes of the cavity. Experimental results show that a microwave power up to 5 kW can be effectively transmitted to excite the mode of the cavity . This cavity can be used to excite large area plasmas     

Effects of the sever on two-stage gyro-TWT amplifiers

The effects of the sever on two-stage gyro-TWT amplifiers were characterized by a self-consistent slow time scale model. Utilization of a sever was demonstrated to be capable of inducing additional launching losses as well as ballistic bunching effects. In addition, some electrons could bunch on an electron phase equal to 3π/2 at the beginning of the second stage as a result of a large and sharp change of the wave’s phase if the modulation of the electron beam in the first stage was strong. Calculated results further indicated that the performance was more sensitive to the position of sever than the length of the sever. Asymmetric interaction structures with the first stage being shorter than the second stage demonstrated higher saturated powers and wider bandwidths along with exhibiting more resistance to the velocity spread of the electron beam.