ZrO2/SiO2溶胶-凝胶薄膜膜层间的渗透行为

分别以丙醇锆和正硅酸乙酯为原料,采用溶胶-凝胶工艺制备了性能稳定的ZrO2和SiO2溶胶。用旋转镀膜法在K9玻璃上分别制备了单层SiO2薄膜、单层ZrO2薄膜、ZrO2/ SiO2双层膜和SiO2/ZrO2双层膜。采用原子力显微镜观察了薄膜的表面形貌,用椭偏仪测量薄膜的厚度与折射率,用紫外-可见光分光光度计测量了薄膜的透射率。对薄膜的透射光谱和椭偏仪模拟的数据进行分析,发现SiO2/ZrO2双层膜之间的渗透十分明显,而ZrO2/SiO2双层膜之间几乎不发生渗透。利用TFCalc模系设计软件,采用三层膜模型对薄膜的透射率进行模拟,得出的透射曲线与用紫外-可见光分光光度计测量的透射曲线十分符合。     

The effect of terminal chain modifications on the mesomorphic properties of 4,4′-disubstituted diphenyldiacetylenes

The typical sidewalls produced in the fabrication of protrusion electrodes are proposed to create a low voltage (4.5 V_rms) and high transmittance (93%) blue-phase liquid crystal display (BP-LCD). The tilted electrodes produce a strong horizontal electrical field that reduces the operating voltage considerably. The common problem of the ‘dead zones’ is solved by reflecting the light onto the electrodes. In order to estimate the phase retardation of the reflected light, a ray tracing simulation program for anisotropic mediums has been developed. The proposed device is more competitive than vertical field switching based BP-LCD and also, has the advantages of protruded in-plane-switching structures. These facts make this technology a potential candidate for the next generation of BP-LCDs.     

Optochemical Sensor for Ammonia Based on a Lipophilized pH Indicator in a Hydrophobic Matrix

Abstract

An optical sensor for the determination of ammonia in water based on ion pairing has been investigated. A pH-sensitive dye is immobilized as an ion pair in a silicone matrix. The colour of the dye changes from yellow to blue depending on the concentration of ammonia in the sample solution. This change is reversible. The concentration of ammonia can be determined by measuring the transmittance at a given wavelength.

All measurements were performed with a dual-beam optical meter. The measurement range was from 5.9 × 10^?7 to 1 × 10^?3 M (0.01 to 17 mg/l) in 0.1 M phosphate buffer of pH 8. The detection limit was 10 μg/l. The response times at a flow rate of 2.5 ml/min were 4 min for t₉₀ and 10 min for t₁₀₀ at a change from 41.9 to 82.5 μM ammonia and 12 min for t₉₀ and 48 min for t₁₀₀ at a change from 160 to 0 μM ammonia. The operational lifetime of the ammonia sensor was limited to a period of a few days only. A continuous decrease in baseline signal and relative signal change was observed over the whole measurement. The storage stability was more than 10 months (dry). With respect to possible application of the ammonia sensor to environmental analysis, the influence of pH, typical interferences, such as amines and various detergents on the sensor response was investigated. No interference due to pH was observed in the range from pH 5 to pH 9. With methyl- and ethylamine the response was not completely reversible. The sensor was affected by cationic detergents, but not by anionic or neutral detergents.     

分数导数结合傅里叶最小二乘拟合处理含噪音的重迭信号

提出了一种含噪音重迭信号的综合处理方法 :先用傅里叶最小二乘法拟合噪音数据 ,然后对拟合后的信号求 2 .5次导数 ,在对模拟数据研究的基础上 ,讨论了求导后峰位漂移及其影响因素 ,给出了一个用于矫正峰位值的经验公式。用该方法对模拟和实际的紫外含噪音重迭信号进行处理 ,结果良好     

紫外-可见吸收光谱结合高斯多峰拟合技术测定甲基红酸离解常数

在一定pH值范围内,甲基红(MR)水溶液紫外-可见吸收光谱特征是酸式甲基红(HMR)最大吸收峰((530±15)nm)与碱式甲基红(MR-)最大吸收峰((435±20)nm)叠合在一起.本文用高斯多峰拟合技术实现了HMR和MR-叠合峰的分峰拟合计算.拟合计算输出两个吸收峰的积分面积即峰强度A1和A2,A1和A2之比与MR-和HMR浓度之比.进而计算甲基红水溶液酸离解平衡常数pKa.用本方法测量298.15K时的pKa值为4.76.拟合优度高,拟合度R2、拟合优度χ2分别达到0.998和10-5以下.深入探讨了表面活性剂十二烷基硫酸钠(SDS)、十六烷基三甲基溴化铵(CTAB)聚集行为对甲基红pKa的影响.与传统分光光度测量方法相比,紫外-可见吸收光谱结合高斯多峰拟合技术结果更可靠,测量步骤和数据处理过程更简单,更具有普适性.     

喷涂法构筑二氧化硅纳米粒子涂层及其光学和润湿性质

采用Stöber方法,通过调节反应温度及乙醇和水的体积,合成了不同粒径的二氧化硅纳米粒子.以合成的粒径为20 nm的二氧化硅纳米粒子为原料,采用简单、方便的喷涂方法在玻璃片上构筑了纳米粒子涂层.在550 ℃煅烧二氧化硅纳米粒子涂层,增强了二氧化硅纳米粒子在玻璃片上的附着力.用1H, 1H, 2H, 2H-全氟辛基三乙氧基硅烷修饰之后,二氧化硅纳米粒子涂层的表面润湿性由亲水性转变为疏水性.通过喷涂法制备的二氧化硅纳米粒子涂层具有减反增透效果,当二氧化硅纳米粒子质量分数为0.48%、循环喷涂沉积数为3时,涂层在可见光范围内的最大透光率可达95.5%.用扫描电子显微镜观测涂层表面形貌发现,喷涂法制备的涂层是均匀的、可控的.喷涂技术构筑纳米粒子涂层具有简单快速、可大面积应用等优点.     

扫描式电感耦合等离子体光谱仪谱线峰位移的机理研究

通过对扫描式电感耦合等离子体原子发射光谱仪(ICP-AES)出射光谱线峰位移(Δλ)的机理研究,发现温度的变化、波长的变化以及光谱仪机械的系统误差是产生谱线峰位移的主要因素,首次测量了谱线峰位移与波长变化之间的非线性函数关系曲线Δλ-λ,以及谱线峰位移与温度变化之间的非线性函数关系曲线Δλ-T,并用多项式方程表达了这些函数关系。本研究还发现,不同的光栅单色仪有近似相同的Δλ-λ函数关系曲线,但是Δλ-T的函数关系曲线却很不相同。利用这些非线性函数方程式,设计开发了扫描式ICP-AES光谱仪的智能波长校正装置(IWC),用它取代传统的局部恒温系统及谱线描迹法进行样品分析的结果表明,智能波长校正的ICP光谱仪(ICP-IWC)谱线峰定位精度高,具有省时、安全、结构简单的特点,有广阔的应用前景。     

Investigation on False Peak Phenomena in On-line Sweeping Technique in MEKC

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The microstructure and optical transmittance thermal analysis of sodium borosilicate bio-glasses

The conditions to fabricate the bulk porous specimens have been studied on account of sodium borosilicate (NBS) glasses. Glass composition, heat treatment at phase separation and TiO₂ addition have been considered in this study. Original glass samples of composition in mol%: sample A: 9.19 Na₂O - 23.58 B₂O₃ - 67.23 SiO₂, sample B: 9.29 Na₂O - 3.17 TiO₂ - 23.82 B₂O₃ - 63.72 SiO₂ were prepared by melting reagent grade chemicals (Na₂CO₃, HBO₃, SiO₂ and AgNO₃) in platinum crucibles at 1480°C for 1 h in air. The melts were poured onto stainless steel plates and were annealed at 500°C for 0.5 h after cooling. Thus, obtained samples were phase separated at 700°C for 2, 15, 25 and 50 h to study their microstructure by scanning electron microscope (SEM). Besides the direct study of the microstructure by SEM, information on glass structural changes of samples are provided by measuring in situ changes by the optical transmittance thermal analysis. The isothermal measurements were carried out at 700, 720 and 740°C. The temperature of phase separation, the leaching and nucleator addition (TiO₂), significantly influence the microstructure of the resulting leached product. TiO₂ additive seems to suppress crystallization of cristobalite: especially at the extended above heat treatment phase separation runs. The phase-separated domains of glasses containing above 80 moles of SiO₂ are so small that it is very hard to observe them by SEM. The glass composition in our case was selected in a way to have relatively large phase separated areas easily observed by SEM at magnification 20 000·. The influence of TiO₂ is not too pronounced. It seems to suppress the cristobalite crystallization, especially of longer heating runs. The image analysis of leached glasses shows the prevailing content of the skeletal phase in a comparison to pores. The TiO₂ content diminishes the content of the skeletal phase. This revised version was published online in July 2006 with corrections to the Cover Date.     

Using a Novel and Easy-to-Use Sandwich Structure Device to Evaluate the Cooling Properties of Cool Materials

A number of cool materials have been designed and used in hot weather to minimize the heat coming from sunlight. Traditionally, solar reflectance and infrared emittance were measured to characterize the cooling properties of cool materials. However, these methods could represent the cooling property only indirectly. In this work, a sandwich structure device that can straightforwardly measure the cooling properties of cool materials was designed. Two cool materials, including high-density polyethylene (HDPE) and polyvinyl chloride (PVC), were selected to verify the device. For the purpose of comparison, UV-vis-NIR spectral characterization was also used to evaluate the cooling properties of the selected materials. The results, especially for the HDPE/Green 260 composite sample, which presents much lower solar reflectance but better cooling property, indicated that the cooling properties cannot be entirely represented by only the reflectance or transmittance, and the sandwich structure device was able to make up for this deficiency.