《功能高分子材料》课堂提问的生长点

《功能高分子材料》内容繁多、概念复杂、专业性强、教学课时少,如何在有限的课堂教学时间内提高教学效率就显得尤为重要。在《功能高分子材料》教学时,为了提高课堂提问的效率,教师可从如下方面来挖掘课堂提问的生长点:(1)在新旧知识的联系处提问;(2)在概念和原理的"关键处"提问;(3)在"最近发展区"处提问;(4)在学生思维障碍处提问;(5)在知识结构处提问;(6)在科学研究方法处提问;(7)在课程核心处提问。     

光谱法研究变性剂诱导的猪胃蛋白酶和牛血清蛋白折叠中间态的分布和过渡

利用紫外光谱和荧光光谱分别测定了变性剂诱导的猪胃蛋白酶和牛血清蛋白的残余活性,并根据它们的两个特征展开参数定量描述了猪胃蛋白酶和牛血清蛋白天然态、折叠中间态和完全展开态随变性液中变性剂浓度的分布和过渡。结果表明,在盐酸胍诱导的猪胃蛋白酶"三态"去折叠过程中,当盐酸胍浓度约为1.5mol/L时,折叠中间态的浓度达到最大,约占溶液中总猪胃蛋白酶的12%;在脲诱导的牛血清蛋白"三态"去折叠过程中,当脲浓度约为2.0mol/L时,折叠中间态的浓度达到最大,约占溶液中总牛血清蛋白的41%;而在盐酸胍诱导的牛血清蛋白"四态"去折叠过程中,当盐酸胍浓度约为0.4mol/L、1.2mol/L时,第一和第二折叠中间态浓度分别达到最大,约占溶液中总牛血清蛋白的20%和70%。     

非高斯噪声对非线性系统的影响

文章采用了路径积分近似、泛函近似两种近似理论推导出了含非高斯噪声并且噪声之间存在耦合的光学双稳系统的定态分布以及平均首通时间的表达式。分析了偏离高斯噪声参量，噪声间的耦合强度对噪声诱导的类相变的影响。结果表明：改变噪声间的耦合强度能诱导重复类相变，改变偏离高斯噪声参量能诱导一级类相变。分析了偏离高斯噪声参量，噪声间的耦合强度对平均首通时间的影响。结果表明：改变噪声间的耦合强度，偏离高斯噪声参量皆能使平均首通时间曲线从单调递减变为单峰。采用了数值模拟分析定态分布以及平均首通时间，数值模拟的结果与理论分析结果相一致，从而验证了理论近似的可行性。     

海南草豆蔻及其主要活性组分、金属元素含量的谱学测定

采用红外光谱、紫外光谱、荧光光谱及微波消解电感耦合等离子体质谱法对海南白沙和霸王岭两个产地的草豆蔻进行了分析。其乙醇提取物的红外光谱都具有1 051,1 390,2 976及3 300cm~(-1)左右表征黄酮类成分的特征吸收峰,二阶红外导数谱图显示了在2 977.72及2 899.94有相似吸收峰,在1 922.36及1 650.87cm~(-1)有显著差异吸收峰,可以鉴定区分海南不同产地的草豆蔻。利用紫外光谱法表征了两个不同产地草豆蔻的特征谱图,并根据有关的吸收原理,建立了测定草豆蔻植物中主要组分山姜素与豆蔻明含量的方法,获得了良好的分析精密度(0.42%~0.29%)和回收率(84.28%~117.41%)。测得白沙草豆蔻中山姜素和豆蔻明的含量分别为4.23%和3.83%,而霸王岭的分别为3.72%和3.34%。荧光测定结果表明,不同产地的草豆蔻乙醇提取物具有相似的荧光发射及激发光谱谱图,荧光强度的差别也再次证明白沙草豆蔻乙醇提取物的浓度大于霸王岭的。利用微波消解电感耦合等离子体质谱法分析了草豆蔻中的K,Ca,Mg,Na,Al,Fe,Mn,Cu,Zn等十七种金属元素及其含量。该研究为定性、定量地鉴定区别不同产地或不同种植批次的草豆蔻及测定其中主要活性组分的含量建立了简单可行的方法;根据实验测得的金属元素种类及含量的结果,可为进一步开发利用草豆蔻及提高食品安全意识提供更好的理论依据。     

Temperature characterizations of silica asymmetric Mach-Zehnder interferometer chip for quantum key distribution

Quantum key distribution (QKD) system based on passive silica planar lightwave circuit (PLC) asymmetric Mach-Zehnder interferometers (AMZI) is characterized with thermal stability, low loss and sufficient integration scalability. However, waveguide stresses, both intrinsic and temperature-induced stresses, have significant impacts on the stable operation of the system. We have designed silica AMZI chips of 400 ps delay, with bend waveguides length equalized for both long and short arms to balance the stresses thereof. The temperature characteristics of the silica PLC AMZI chip are studied. The interference visibility at the single photon level is kept higher than 95% over a wide temperature range of 12 ℃. The delay time change is 0.321 ps within a temperature change of 40 ℃. The spectral shift is 0.0011 nm/0.1 ℃. Temperature-induced delay time and peak wavelength variations do not affect the interference visibility. The experiment results demonstrate the advantage of being tolerant to chip temperature fluctuations.     

咪唑侧基功能化聚离子液体修饰的混合模式色谱固定相的制备及其色谱性能

该文合成了咪唑侧基功能化的离子液体单体1-(4-乙烯基苄基)-3-氰甲基溴化咪唑盐,通过表面引发原子转移自由基聚合将该单体接枝到硅胶表面,制备了一种新型混合模式色谱固定相。采用红外光谱、元素分析及热重分析对其结构进行表征。该色谱固定相具有良好的分离能力。通过研究流动相pH对物质保留的影响,验证了物质在该固定相上存在反相-离子交换保留机理。通过与十八烷基硅烷键合硅胶固定相比较,证实了该聚离子液体固定相对物质保留提供了π-π作用。结果表明,对咪唑侧基功能化是制备新型离子液体固定相的可行方法。     

High efficiency,small size,and large bandwidth vertical interlayer waveguide coupler

Since the advent of three-dimensional photonic integrated circuits,the realization of efficient and compact optical interconnection between layers has become an important development direction.A vertical interlayer coupler between two silicon layers is presented in this paper.The coupling principle of the directional coupler is analyzed,and the traditional method of using a pair of vertically overlapping inverse taper structures is improved.For the coupling of two rectangular waveguide layers,a pair of nonlinear tapers with offset along the transmission direction is demonstrated.For the coupling of two ridge waveguide layers,a nonlinear taper in each layer is used to achieve high coupling efficiency.The simulation results show that the coupling efficiency of the two structures can reach more than 90%in a wavelength range from 1500 nm to 1650 nm.Moreover,the crosstalk is reduced to less than-50 d B by using multimode waveguides at intersections.The vertical interlayer coupler with a nonlinear taper is expected to realize the miniaturization and dense integration of photonic integrated chips.     

Stochastic properties of tumor growth with coupling between non-Gaussian and Gaussian noise terms

Dynamical behavior of tumor-growth model with coupling between non-Gaussian and Gaussian noise terms is investigated. The departure from the Gaussian noise can not only reduce the probability of tumor cells in the active state, induce the minimum of the average tumor-cell population to move toward a smaller non-Gaussian noise, but also decrease the mean first-passage time. The increase of white-noise intensity can increase the tumor-cell population and shorten the mean first-passage time, while the coupling strength between noise terms has opposite effects, and the noise correlation time has a very small effect.     

Influence of limited-view scanning on depth imaging of photoacoustic tomography

We study the influence of limited-view scanning on the depth imaging of photoacoustic tomography. The situation, in which absorbers are located at different depths with respect to the limited-view scanning trajectory, is called depth imaging and is investigated in this paper. The results show that limited-view scanning causes the reconstructed intensity of deep absorbers to be weaker than that of shallow ones and that deep absorbers will be invisible if the scanning range is too small. The concept of effective scanning angle is proposed to analyse that phenomenon. We find that an effective scanning angle can well predict the relationship between scanning angle and the intensity ratio of absorbers. In addition, limited-view scanning is employed to improve image quality.     

巯基葡聚糖凝胶分离富集微乳液增敏间硝基苯基荧光酮光度法测定环境样品中痕量镍

本文研究发现,在微乳液介质中(pH= 10. 4), 镍与间硝基苯基荧光酮(m NPF)反应生成稳定的1∶2 配合物;在606 nm处,其摩尔吸光系数为2.05×105 L·mol-1·cm-1;镍含量在0~0.7μg·mL-1范围内符合比耳定律。测定前,采用巯基葡聚糖凝胶分离富集,以消除共存离子的干扰。用所拟方法测定了环境样品中的痕量镍,结果令人满意。