基于电化学发光和阻抗技术研究DNA单碱基错配

单碱基错配的识别和稳定性差异在核酸多态性研究中至关重要。在同一电化学传感器平台上，采用电化学发光（ECL）和电化学阻抗（EIS）2种技术，协同研究DNA链中不同类型和不同位点的单碱基错配识别和稳定性差异。电极表面具有茎环构象的探针DNA与完全互补DNA、不同类型或不同位点单碱基错配DNA杂交前后的ECL和EIS信号强度变化有显著差异。信号强度变化可揭示单碱基错配识别的稳定性。结果表明，DNA链中心位点的C-A单碱基错配稳定性低于链两端的，靠近键合电极表面双链链端的C-A单碱基错配稳定性低于非键合电极表面双链链端的，同一中心位点C-X碱基对的稳定性顺序为C-G?C-T>C-A≥C-C。研究结果可为核酸多态性研究提供参考。     

基于碳化硅衬底的宽禁带半导体外延

宽禁带半导体具备禁带宽度大、电子饱和飘移速度高、击穿场强大等优势,是制备高功率密度、高频率、低损耗电子器件的理想材料。碳化硅(SiC)材料具有热导率高、化学稳定性好、耐高温等优点,在SiC衬底上外延宽禁带半导体材料,对充分发挥宽禁带半导体材料的优势,并提升宽禁带半导体电子器件的性能具有重要意义。得益于SiC衬底质量持续提升及成本不断降低,基于SiC衬底的宽禁带半导体电子市场占比呈现逐年增加的态势。在SiC衬底上外延生长高质量的宽禁带半导体材料是提高宽禁带半导体电子器件性能及可靠性的关键瓶颈。本文综述了近年来国内外研究者们在SiC衬底上外延SiC、氮化镓(GaN)、氧化镓(Ga₂O₃)所取得的研究进展,并展望了SiC衬底上宽禁带半导体外延的发展及应用前景。     

The first principles investigation of ferrite magnetic response with mismatch stress

The quasi-ferrite model is proposed and an appropriate PBE exchange functional with the spin density functional theory(SDFT) is selected for the calculation of the relation between magnetic moment and residual stress in ferrite using a quantum mechanics code. The relationship between ferrite magnetism and the carbon content is determined,and then a ferrite interstitial solid solution(ISS) model in a low carbon concentration state is replaced with an α- Fe model in the case of majority magnetic calculation. The band structure of the loaded-Fe is compared with that of the unloaded α-Fe. The comparison shows that the energy of Fe atomic 3d orbital changes a little,while the energy of electron orbital of iron core below 3d almost keeps unchanged. The relationship between the magnetic moment and the stress appears intermittent due to the Bragg total reflection. The change in the magnetic moment due to lattice mismatch is much larger than that caused by mechanical loading.     

双路激光混沌复用系统的混沌同步及安全性能研究

针对一种新型的双路激光混沌复用系统, 建立相应的速率方程模型, 详细分析了两个主激光器的单个参数失配、多个参数同时失配、反馈强度差异以及频率失谐对混沌同步性能的影响, 并对此复用系统的安全性能和频谱性能进行了研究. 研究结果表明: 采用参数失配方案, 通过合理选择两个主激光器的参数, 可以保证两个主激光器之间的同步性能较差而两对主从激光器间实现高品质的混沌同步, 因此满足双路激光混沌复用的条件; 两个主激光器之间的参数失配对它们之间的同步性能影响较大, 然而对配对主从激光器间同步性能的影响并不明显, 进一步说明参数失配方案的有效性和可行性. 另外, 通过自相关函数和频谱分别分析混沌复用信号的时域和频域特征, 发现双路激光混沌复用系统可提供更高的安全性.     

Effect of material selection and background impurity on interface property and resulted CIP-GMR performance

In this paper, we investigated the effect of background base pressure, wafer-transferring time between process modules, and stack layer material selection on the current-in-plane giant magneto-resistive (CIP-GMR) interface properties and the resulted CIP-GMR performance. Experimental results showed that seed layer/AFM interface, AFM/pinned layer (PL) interface, pinned layer/Ru interface, and reference layer (RL)/Cu spacer interface are among the most critical ones for a CIP-GMR device. By reducing the background impurity level (water moisture and oxygen), optimizing the wafer process flow sequence, and careful stack-layer material selection, such critical interfaces in a CIP-GMR device can be preserved. Consequently, a much robust GMR performance control can be achieved.     

Dual-wavelength nonvolatile holographic storage

A simple, convenient and effective way is demonstrated to reduce the field losses of the reconstructed image in the dual-wavelength nonvolatile holographic storage by adding a cylindrical lens in the holographic recording configuration. The experimental results show that this technique makes the dual-wavelength nonvolatile holographic storage compact and practical.     

Effects of phosphorous beam equivalent pressure on GaInAsP/GaAs grown by solid source molecular beam epitaxy with a valve phosphorous cracker cell

We report the growth and characterization of GaInAsP films on GaAs substrates by solid source molecular beam epitaxy (SSMBE) using a valve phosphorous cracker cell at varied white phosphorous beam equivalent pressure (BEP). It is found that the GaInAsP/GaAs can be easily grown with the solid sources, and the incorporated phosphorous composition as a function of the beam equivalent pressure ratio, R=f_P/(f_P+f_As), can be well described by a parabolic relationship. With the increase of the incorporated phosphorous composition, the GaP-, InP-, InAs- and GaAs-like phonon modes shift towards opposite directions and their emission intensities also change. The first three modes shift to larger wave numbers while the last one shifts to smaller wave number. The lattice mismatch, Δa/a, of the materials grown with varied phosphorous BEP follows a linear relationship. Photoluminescence (PL) measurements reveal that as the phosphorous BEP ratio increases, the peak position or energy band gap of the material shifts towards higher energy; the full-width at half-maximum (FWHM) becomes narrower, and the luminescence intensity becomes higher. In addition, the materials also show smooth surfaces that do not change significantly with phosphorous beam equivalent pressure.     

Mismatches Improve the Performance of Strand‐Displacement Nucleic Acid Circuits

Catalytic hairpin assembly (CHA) has previously proven useful as a transduction and amplification method for nucleic acid detection. However, the two hairpin substrates in a CHA circuit can potentially react non‐specifically even in the absence of a single‐stranded catalyst, and this non‐specific background degrades the signal‐to‐noise ratio. The introduction of mismatched base pairs that impede uncatalyzed strand exchange reactions led to a significant decrease of the background signal, while only partially damping the signal in the presence of a catalyst. Various types and lengths of mismatches were assayed by fluorimetry, and in many instances, our MismatCHA designs yielded 100‐fold increased signal‐to‐background ratios compared to a ratio of 4:1 with the perfectly matched substrates. These observations could be of general utility for the design of non‐enzymatic nucleic acid circuits.     

三维光存储中折射率失配引起的球差补偿

为实现三维光存储中折射率失配引起的球差补偿,建立了光学存储系统模型,获得了折射率失配引起的波前偏差函数与存储深度的表达式.采用泽尔尼克循环多项式对波前偏差函数进行补偿展开.在双光子荧光和单光子共焦荧光读出方式下,均可获得读出荧光强度与存储深度的关系:在折射率失配引起的球差未得到补偿矫正的情况下,存储深度在200 μm左右读出荧光强度基本上下降为零;当折射率失配引起的初级球差被补偿矫正后,读出荧光强度随存储深度的下降得到较好改善;当折射率失配引起的二级球差被补偿矫正后,存储深度在1 mm内存储点强度随深度基本上没有明显地变化.并且对像差补偿方法进行了具体地分析.     

时隙交织信道的四波混频均衡再生

给出了适用于多波长再生的数据抽运简并四波混频(FWM)耦合模方程组,提出了时隙交织波长信道再生的准相位匹配均衡方法。从优化设计简并FWM相位失配因子入手,针对实验室已有的光纤,实现了4个固定波长信道的均衡再生;通过设计光纤参数,在一定带宽范围内可实现任意4个波长的均衡再生。计算结果表明,再生输出信号的脉冲峰值功率、消光比(ER)和Q值之间的差异分别不超过0.25dB、0.42dB和1.5。