基于十字形结构的相位梯度超表面设计与雷达散射截面缩减验证

基于十字形结构设计了一种在雷达波低频段极化不敏感的相位梯度超表面, 并通过仿真和实验进行了验证. 不同金属十字周期结构单元复合, 在超表面上形成附加的平行波矢分量, 对反射波波前进行调控, 获得超表面后向雷达散射截面积(RCS)缩减. 在设计波段内, 超表面在法线方向的单站RCS缩减达18.19 dB, 偏离法线-30°–+30°范围的单站RCS 平均缩减达8 dB; 仿真与实验结果符合较好.     

Synthesis and Characterization of Polymers Containing Rare Earth Metals

Europium and terbium salts of methacrylic acid (MA) and octanoic acid (OCA) were prepared by a method similar to that described in the literature. Either Eu(MA)₃ or Tb(MA)₃ with three double bonds (C?C) was used as a crosslinker containing rare earth metal ions, but the octanoic acid salts were used as additives. The salts were dissolved in methacrylic acid (<20%) and then copolymerized with methyl methacrylate (>80%) using AIBN (0.2 wt%) as initiator. The two types of polymers, one containing Eu(MA)₃ or Tb(MA)₃ and the other with Eu(OCA)₃ or Tb(OCA)₃, were synthesized by bulk copolymerization in molds made of two glass plates and characterized. The fluorescence spectroscopy of these polymers under ultraviolet/visible excitation light was investigated. The fluorescence excitation and emission spectra of the polymers showed the characteristic spectra of the free Eu³⁺ or Tb³⁺. The fluorescence intensity of the rare earth metal ions increased with increasing rare earth metal content. Fluorescence measurements for Eu(MA)₃, Tb(MA)₃, and Eu(OCA)₃ polymers do not display fluorescence quenching behavior within the range of the rare earth metal content used in our experiments. But for Tb(OCA)₃ polymers, this phenomenon was observed, illustrating that ionic aggregates exist in Tb(OCA)₃ polymeric systems.     

混沌时间序列多步自适应预测方法

针对混沌时间序列局域自适应预测方法在多步预测中预测器系数无法调节的问题，根据混沌时间序列的短期可预测性及自适应算法的自适应跟踪混沌运动轨迹的特点，提出了混沌时间序列多步自适应预测方法.仿真结果表明，此方法的多步预测性能明显好于局域自适应预测方法的多步预测性能. 关键词： 多步自适应预测方法 局域自适应预测方法 混沌时间序列     

用光电传感器测量电机转速

基于传感器的转速测量方法较多,总体分为模拟式和数字式两种.本文重点研究数字式测量方法.针对光电传感器的原理进行简单介绍,并说明它是如何对电机转速进行测量的.通过实验得到的结果进行了数据分析,用最小二乘法拟合出了线性表达式.     

补骨脂素和异补骨脂素键合人血清白蛋白的比较

将互为同分异构体的两种植物药活性组分补骨脂素和异补骨脂素作为研究对象,利用荧光光谱、紫外光谱、圆二色谱及傅立叶变换红外光谱详细比较研究了这两种香豆素类化合物与人血清白蛋白(HSA)的键合作用.不同光谱的结果定性、定量地显示了HSA二级结构变化的程度.依据荧光滴定实验及Van′t Hoff公式求出了反应的热力学参数(ΔH和ΔS)的值.根据修正后的Stern-Volmer和Scatchard方程和荧光光谱数据分别求得不同温度(296,303,310及318 K)下药物与蛋白相互作用的结合常数及结合位点数;且根据F觟rster偶极-偶极能量转移理论,求得药物与HSA间的键合距离;利用竞争实验确定了药物在HSA上的键合位点为site II.从分子水平上揭示了这两种化合物与HSA相互作用的机制.     

一种新的具有双螺旋结构特征的光学活性分子方的设计、合成及其光学性质

分别从手性构型高度稳定的(R)和(S)-2,2'-二乙炔基-1,1'-联萘模板出发, 通过保护基的控制导入、偶联反应、保护基脱去以及分子间偶合成环4个步骤成功地合成了一种具有螺旋结构特征的新的光学活性分子方(Molecular square)(R,R,R,R)-1和(S,S,S,S)-1. 用MS, IR, UV-Vis, 1H和13C NMR以及元素分析等方法对目标化合物进行了结构表征. 测定并分析比较了2个目标化合物的比旋光度[α]D和圆二色性(CD)等光学性质. 在CH2Cl2溶液中, 异构体(R,R,R,R)-1和(S,S,S,S)-1的[α]25D值分别为+887.3°和-889.7°, 并且其CD谱表现出对称的镜像特征.     

Feature of Energy Spectra of Three-Identical-Particle Systems in Two-Dimensional Space

The Hamiltonian of a model system has been diagonalized numericaUy to obtain the eigenstates and eigenenergies. Three types of permutation symmetries: the antisymmetric, the mixed symmetric and the symmetric symmetries have been covered. The dynamical parameters (i.e., the particle mass and the particle-particle interaction) are taken appropriately for a particles, however a series ,of qualitative features are revealed to be iden tical with those of quantum dot electronic systems in semiconductor heterojunctions. We stress the importance of quantum mechanical symmetries in the understanding of quantum mechanical few-body systems.     

Perturbation of nilpotent semigroups and application to heat exchanger equations

It is shown that the nilpotency is preserved by the perturbed semigroup for a class of perturbation operators. The obtained result is applied to explain mathematically a thermodynamic phenomenon of some heat exchangers.     

Supramolecular interaction of cucurbit[n]urils and coptisine by spectrofluorimetry and its analytical application

The supramolecular interaction of a homologous series of cucurbit[n]uril (CB[n], n = 5, 6, 7, 8) hosts and coptisine (COP) was studied by spectrofluorimetry. All of the CB[n]s were found to react with COP to form 1:1 host-guest stable complexes and the fluorescence intensity of the complexes was greatly enhanced. The apparent association constants of the complexes were 1.44 × 10⁴, 1.28 × 10⁴, 1.86 × 10⁴ and 1.26 × 10⁴ L mol⁻¹ for CB[5], CB[6], CB[7] and CB[8], respectively. In addition, CB[5] and CB[7] exhibited a higher fluorescence signal than CB[6] and CB[8]. The fluorescence intensity of the complex with CB[7] was enhanced 70-fold compared to that of the studied drug itself. Based on the significant enhancement of fluorescence intensity of supramolecular complex, a simple, rapid, highly sensitive, and selective spectrofluorimetric method was developed for the determination of COP in aqueous solution in the presence of CB[7]. At the optimum reaction conditions, a linear relationship was obtained in the range from 0.05 to 1700 ng mL⁻¹ with a detection limit of 0.012 ng mL⁻¹. The proposed method was successfully applied for the determination of the drug in urine and serum samples.     

中性介质鲁米诺电化学发光测定过氧化氢

利用硼酸中性缓冲溶液介质中鲁米诺在正矩形脉冲电压激励下的电化学发光 ,研究了 H2 O2 对鲁米诺电化学发光体系发光强度的增强作用 ,建立了中性介质中测量微量 H2 O2 的电化学发光的新方法。电化学发光强度与 H2 O2 浓度在 5 .4× 10 -8— 2 .2× 10 -7mol/L范围内呈线性关系 ,检出限为 7.1× 10 -9mol/L。该方法适用于涉及过氧化氢生成的生物催化和代谢的中性体系 ,因而可望用作为这些生物体系的一种灵敏的分析方法