高效液相色谱法同时测定心可舒胶囊中齐墩果酸和熊果酸

建立高效液相色谱法同时测定心可舒胶囊中齐墩果酸和熊果酸的含量。采用HypersiL ODSC₁₈（4.6mm×250mm,5μm）色谱柱;流动相:甲醇-乙腈-水=79:5:16（V/V/V）;柱温:30℃;流速:1mL/min;检测波长:210nm。齐墩果酸在2.04—81.60μg/mL浓度范围内线性关系良好（r=0.9998）,熊果酸在5.00—80.00μg/mL浓度范围内线性关系良好（r=0.9998）,齐墩果酸的平均回收率为100.54%,RSD为1.56%,熊果酸的平均回收率为101.10%,RSD为1.13%。该法简单、准确、快捷,可用于心可舒胶囊中齐墩果酸和熊果酸的含量测定。     

AlN/Al dual protective coatings on NdFeB by DC magnetron sputtering

AlN/Al dual protective coatings were prepared on NdFeB by DC magnetron sputtering in a home-made industrial apparatus. Comparing with Al coating, AlN/Al coatings have a denser structure of an outmost AlN amorphous layer following an inner Al columnar crystal layer. The coatings and NdFeB substrate combine well, and moreover, there is occurrence of metallurgy bonding in the interface layer. Both Al and AlN/Al coatings have a good protective ability to NdFeB. Especially, the corrosion resistance of AlN/Al coated NdFeB is improved largely. AlN/Al and Al protective coatings not only do not deteriorate the magnetic properties of NdFeB, but contribute to their slight increase.     

Microstructures and impedance studies of Bi<Subscript>3.15</Subscript>Nd<Subscript>0.85</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript> thin films

Microstructures and impedance characteristics of chemical-solution-derived Bi_3.15Nd_0.85Ti₃O₁₂ thin films were studied as functions of temperature. A dielectric anomaly was found at around 450°C, corresponding to the paraelectric to ferroelectric transition. Via complex impedance studies, grain and grain boundary contributions to the impedance were separated. The resistance of grain and grain boundaries is found governed by the same kind of space charge with an activation energy around 1.1 eV, close to that of oxygen vacancies in perovskite ferroelectrics. The low temperature ac conductance of BNdT thin films shows a frequency dispersion, which can also be ascribed to space charges mainly due to oxygen vacancies. The results were compared with SrBi₂Ta₂O₉ in terms of oxygen vacancy conductivity.     

电流模式SEPIC变换器倍周期分岔现象研究

以SEPIC变换器中前置电感电流为控制对象,建立了SEPIC变换器断续电流模式下的离散时间模型, 并分析了不动点的稳定性.通过相轨图、功率谱图以及分岔图, 发现电路中存在一种特殊的倍周期分岔现象——电路的运行状态经历了1倍周期、 2倍周期、4倍周期再到2倍周期、4倍周期,最终进入混沌状态.实验结果与仿真结果相一致, 证实了SEPIC变换器在断续电流模式下存在这种倍周期分岔现象.     

由单负材料组成的一维对称型光子晶体中的隧穿模

由电单负材料A和磁单负材料B构成了一维对称型光子晶体,数值计算表明其带隙中出现了一隧穿模. 材料层数增加,隧穿模宽度急剧变窄,而其位置不变.隧穿模的位置和宽度对入射角的变化都不太敏感. 材料的几何厚度减小,隧穿模的位置蓝移,而其宽度不变. μ_A, ε_B增加,隧穿模的位置红移,宽度减小. 利用隧穿模的以上特性可以实现对电磁波传播的动态调控.     

Effect of tones on vocal attack time in Cantonese speakers

Vocal attack time (VAT) is the time lag between the growth of the sound pressure signal and the development of physical contact of vocal folds at vocal initiation. It can be derived by a cross-correlation of short-time amplitude changes occurring in the sound pressure and electroglottographic (EGG) signals. Cantonese is a tone language in which tone determines the lexical meaning of the syllable. Such linguistic function of tone has implications for the physiology of tone production. The aim of the present study was to investigate the possible effects of Cantonese tones on VAT. Sound pressure and EGG signals were simultaneously recorded from 59 native Cantonese speakers (31 females and 28 males). The subjects were asked to read aloud 12 disyllabic words comprising homophone pairs of the six Cantonese lexical tones. Results revealed a gender difference in VAT values, with the mean VAT significantly smaller in females than in males. There was also a significant difference in VAT values between the two tone categories, with the mean VAT values of the three level tones (tone 1, 3, and 6) significantly smaller than those of the three contour tones (tone 2, 4, and 5). The findings support the notion that norms and interpretations based on nontone European languages may not be directly applied to tone languages.     

Ultrasound-assisted extraction of three bufadienolides from Chinese medicine ChanSu

In this study, the application of ultrasound-assisted extraction (UAE) method was shown to be more efficient in extracting anti-tumor bufadienolides (bufalin, cinobufagin and resibufogenin) from important animal medicine of ChanSu than the maceration extraction (ME) and soxhlet extraction (SE) method. The effects of ultrasonic variables including extraction solvent, solvent concentration, solvent to solid ratio, ultrasound power, temperature, extraction time and particle size on the yields of three bufadienolides were investigated. The optimum extraction conditions found were: 70% (v/v) methanol solution, solvent to solid ratio of 10ml/g, ultrasound power of 125W, temperature of 20°C, extraction time of 20min and particle size of 60-80 mesh. The extraction yields of bufalin, cinobufagin and resibufogenin were 43.17±0.85, 52.58±1.12, 137.70±2.65mg/g, respectively. In order to achieve a similar yield as UAE, soxhlet extraction required 6h and maceration extraction required much longer time of 18h. The results indicated that UAE is an alternative method for extracting bufadienolides from ChanSu.     

连续纠缠态表象的几种Schmidt分解、物理意义与应用

在两粒子连续纠缠态表象|η〉的基础上分别导出了此纠缠态在坐标、动量表象和粒子数表象中的Schmidt分解,阐述了其物理意义.并且,用|η〉的Schmidt分解直接给出单模压缩算符对纠缠态的作用结果、双模平移算符的纠缠态表象以及平移算符在Fock空间的矩阵元.文章的讨论可以推广到多粒子连续纠缠态情形.     

Enhanced photocatalytic activity of TiO2 thin film coating on microstructured silicon substrate

Photocatalytic TiO2 thin film is prepared by sol–gel technique on microstructured silicon substrate produced by femtosecond laser cumulative irradiation. The photocatalytic activity is evaluated by the degradation of methylene blue (MB) solution under ultraviolet (UV) irradiation. For 6-ml MB solution with initial concentration of 3.0×10~-5 mol/L, the degradation rate caused by TiO2 thin film of 2-cm~2 area is higher than 70% after 10-h UV irradiation. Microstructured silicon substrate is found to enhance photocatalytic activity of the TiO2 thin film remarkably. The femtosecond laser microstructured silicon substrate is suitable to support TiO2 thin film photocatalysts.     

Temperature-insensitive Mach-Zehnder interferometric strain sensor based on concatenating two waist-enlarged fiber tapers

A novel temperature-insensitive strain sensor,based on an in-line Mach-Zehnder interferometer,is fabricated by concatenating two waist-enlarged fiber tapers separated by a short piece of photonic crystal fiber. The interference spectrum of the proposed sensor is analyzed in detail.Experimental results demonstrate that this sensor has a strain sensitivity of.3.02 pm/μεand maintains the temperature insensitivity feature. The proposed sensor has great potential in diverse sensing applications due to its advantages,such as its compact size,low cost,and simple fabrication process.