Preparation and Characterization of a Sol-Gel Prepared Ferroelectric Sandwich Structure

A novel silicon-based PbTiO₃/Pb(Zr,Ti)O₃/PbTiO₃ (PT/PZT/PT) sandwich structure has been prepared using a sol-gel method. The annealing temperature is greatly reduced compared with those structures without PT layers. Capacitance-voltage (C-V), leakage current-voltage (I-V), polarization-field (P-E), dielectric-frequency response and polarization fatigue of the sandwich structure are examined. The relative dielectric constant, the coercive field and the remanent polarization of the PZT films are measured to be about 900, 18 kV/cm and 16 C/cm² respectively. The current density is less than 5 × 10^–9 A/cm² below 200 kV/cm. The dielectric constant of the structure remains constant at low frequency, and decreases to some degree at high frequency. The retained polarization does not change significantly after 8 × 10⁹ read/write cycles. The PZT films are proved to have very good dielectric and ferroelectric properties. The new PT/PZT/PT sandwich structure can be valuable for memory devices and other applications.     

PT二次回路压降自适应补偿方法研究

通过分析电压互感器二次回路的特点及其压降产生的原因，设计了电压互感器二次回路压降自适应补偿控制器，为提高电能计量准确度、减小由于计量误差造成的电量损失提出了一种新的思路。     

高精度温度控制系统的研究

设计并实现了一种基于自动优化的PID算法控制技术和16位单片机(SCM)SPCE061A的高精度水温控制系统.由传感器PT_1000和16位AD LTC1606获取温度信号,使用U'nsp IDE环境提供的API函数进行控制程序设计,通过SPCE061A实现温度实时控制.实验结果表明该系统可实时精密的控制水温,且稳定迅速、操作简单并能语音播报和显示温度值.可广泛应用于工业、农业、食品等部门的温度控制部分.     

差分输入双积分电路在热电阻测温中的应用

针对常规分立双积分AD只能处理单端信号的问题,给出了一种输入和基准电压均支持差分信号的分立差分双积分AD。在热电阻测量中,把热电阻和基准电阻串联同一回路,以基准电阻压降作为基准,对热电阻的压降进行测量,并从软硬件两个方面对常见的误差因素进行对消处理。实验表明,该电路用于PT100测温时,跳字不超过0.1℃,精度可以达到±0.1℃,且对运放型号无特殊要求,是一种低成本、高精度的温度测量方案。     

0.74Pb(Mg_(1/3)Nb_(2/3))O_3-0.26PbTiO_3薄膜的光学性能研究

采用磁控溅射法,选用LaNiO3(LNO)作为缓冲层和电极层,在硅基片上成功地制备出了0.74Pb(Mg1/3Nb2/3)O3-0.26PbTiO3(PMN-0.26PT)铁电薄膜.X射线衍射(XRD)分析表明薄膜具有沿(110)方向择优取向的钙钛矿结构.利用NKD光谱测试仪测试了薄膜的反射谱,并使用最小二乘法进行拟合分析得到其折射率和消光系数.在沉积温度为500℃时,薄膜具有更为均匀和致密的微观结构.在波长为633 nm时,该薄膜的折射率大小为2.41.薄膜的折射率和消光系数随着光子能量的增加而增加.薄膜的这些光学特性使其有望在低压电光转换器、光波导等器件中应用.     

Topological insulating phase for anti-Hermitian Hamiltonians

We study classification of anti-Hermitian topological insulators based on the discrete symmetries: time-reversal, particle-hole and chiral symmetries. Contrary to the most general form of non-Hermitian systems, bulk boundary correspondence can hold in anti-Hermitian topological systems. We map a topologically nontrivial Hermitian Hamiltonians into an anti-Hermitian system and we show that the standard table of topological insulators can be used for anti-Hermitian Hamiltonians.     

农残水平测试中数据多态性分析及指定值估计研究

对全国农残水平测试中毒死蜱、氯氰菊酯数据进行统计分析,在数据统计分布特征研究基础上,使用内核密度估计进行数据多态性分析,使用bootstrap模拟取样法对数据样本值重复取样,以获得稳健的水平测试样品待测物含量代表值估计、标准误差及置信区间描述,证明以bootstrap模拟取样法获取的均值与标准偏差作为有限单次样本代表值是合理、有效的,解决了四分位稳健统计方法对非正态多态分布代表值估计不稳定问题及取样理论中取样样本数限制的瓶颈,为能力验证计划指定值的获取提供了一种新方法。     

非天然D-型氨基酸生物转化中酶的纯化及其基因序列

D-海因酶 (D- Hydantoinase,HDTase )和 N -氨甲酰基 - D-氨基酸酰胺水解酶 (D- Carbam oylase,DCase )是医药和食品工业上用于生物转化 D-型氨基酸的酶。为了用人工酶替代现用的天然酶转化工艺 ,我们用热变性、硫酸铵分级及 Q - Sepharose、Phenyl- Sepharose、Superose12等多步柱层析 ,从现用菌株 No.2 2 6 2中纯化了 HDTase和 DCase,二酶均达到 SDS- PAGE纯 ,经 N -端序列分析 ,HDTase和 DCase的 N -末端氨基酸序列分别为 :MDKL IKNGTI和 MTRQKIL AF。首先 ,根据酶的 N -末端氨基酸顺序推论并合成了正向多核苷酸简并引物 ,然后按蛋白质数据库资料 ,在比较不同菌株氨基酸残基同源性基础上 ,化学合成了数对反向多核苷酸引物 ,以菌株 No. 2 2 6 2基因组 DNA为模板 ,经 PCR扩增获得了 HDTase的部分基因序列 (～ 70 0 bp )和 DCase的全部基因序列 (912 bp ) ,为使人工酶用于非天然 D-型氨基酸的生物转化奠定了基础。     

Solvable relativistic quantum dots with vibrational spectra

For Klein-Gordon equation a consistent physical interpretation of wave functions is reviewed as based on a proper modification of the scalar product in Hilbert space. Bound states are then studied in a deep-square-well model where the spectrum is roughly equidistant and where a fine-tuning of the levels is mediated by -symmetric interactions (composed of imaginary delta functions) which mimic creation/annihilation processes. Presented at the 3rd International Workshop “Pseudo-Hermitian Hamiltonians in Quantum Physics”, Istanbul, Turkey, June 20–22, 2005.     

以PT-C_(18)色谱预柱在线流动注射分离富集火焰原子吸收法测定银

使用 PT- C18色谱预处理柱 ,以双硫腙为螯合剂 ,甲醇为洗脱剂 ,采用流动注射在线分离富集与原子吸收联用技术 ,对银的测定进行了研究。 1 min富集 ( 4 .2 m L)的富集倍率 2 4 ,检出限为 0 .6 2μg/ L,相对标准偏差为 1 .8% ( n=7)。