黄原酯棉分离富集和石英缝管技术的FAAS测定环境水中痕量铅

本文研究了黄原酯棉富集铅的条件，探讨了应用石英缝管技术测定铅的方法。实验表明ｐＨ＝７左右时，黄原酯棉能够定量地富集水中痕量铅，以１％ＨＮＯ３、水浴２０ｍｉｎ即可定量解脱。应用石英缝管技术可比常规火焰测定铅的灵敏度提高３．３倍。本方法可应用于野外富集。     

Spectral,electron microscopic and chemical investigations of gamma-induced purple color zonings in amethyst crystals from the Dursunbey-Balıkesir region of Turkey

Amethyst crystals on matrix specimens from the Dursunbey-Bal?kesir region in Turkey have five representative purple color zonings: dark purple, light purple, lilac, orchid, and violet. The purple color zonings have been analyzed with optical absorption spectra in the visible wavelength region, chemical full trace element analyses (inductively coupled plasma-atomic emission spectroscopy and inductively coupled plasma-mass spectroscopy), and scanning electron microscopic images with high magnification. It can be proposed that the production of the purple color in amethyst crystals is due to three dominant absorption bands centered at 375, 530, and 675 nm, respectively. In addition, the purple color zonings are also due to four minor absorption bands centered at 435, 480, 620, and 760 nm. X-ray diffraction graphics of the investigated amethyst crystals indicate that these crystals are composed of a nearly pure alpha-quartz phase and do not include any moganite silica phase and/or other mineral implications. Trace element analyses of the amethyst crystals show five representative purple color zonings, suggesting that the absorption bands can be mainly attributed to extrinsic defects (chemical impurities). However, another important factor that influences all structural defects in amethyst is likely to be the gamma irradiation that exists during amethyst crystallization and its inclusion in host materials. This gamma irradiation originates from the large underlying intrusive granitoid body in the region of amethyst formation. Irradiation modifies the valence values of the impurity elements in the amethyst crystals. It is observed that the violet-colored amethyst crystals have the most stable and the least reversible coloration when exposed to strong light sources. This situation can be related to the higher impurity content of Fe (2.50 ppm), Co (3.1 ppm), Ni (38 ppm), Cu (17.9 ppm), Zn (10 ppm), Zr (3.9 ppm), and Mo (21.8 ppm).     

Visible Channeled Spectra of a Multilayer Wood Filter

The transmission factor of multilayer Wood filters containing quartz and rutile layers was simulated in order to avoid the experimental trials for obtaining optical filters with predicted transmission. The main refractive indices of uniaxial crystals—quartz and rutile—were interferometrically determined and Cauchy constants were obtained by simulation. The transmission factor of optical devices consisting of quartz and rutile layers was simulated using the Maple Program.     

Determination of Bismuth in Bottled and Mineral Water Samples at Trace Levels by T-Shaped Slotted Quartz tube-Atom Trap-Flame Atomic Absorption Spectrometry

An accurate and reliable analytical method for the determination of bismuth at trace levels in bottled and mineral water samples has been developed based on hydrogen assisted T-shape slotted quartz tube-atom trap-flame atomic absorption spectrometry (T-SQT-AT-FAAS). Conventional FAAS is not sufficiently sensitive to measure trace and ultra-trace levels of metals due to the low nebulization efficiency and short residence time of atoms in the light path. To overcome this problem, atom trapping with a T-shaped slotted quartz tube was coupled to the FAAS system. Bismuth atoms were trapped on the surface of T-SQT and released by hydrogen gas, which provided a reducing environment. All of the system parameters such as flame type, hydrogen flow rate, the height of T-SQT from the burner head, and trapping period were optimized to enhance the analytical signal to attain low detection limits. After obtaining the optimum conditions, the limit of detection and limit of quantitation of the developed method were found to be 0.95 and 3.2?µg L^?1, respectively. Recovery values were obtained between 90% and 104% that showed good accuracy and applicability of the proposed method to the analysis of bottled and mineral water samples.     

110°C thermoluminescence glow peak of quartz — A brief review

The 110°C glow peak of quartz, though unstable at room temperature, has worked wonderfully in archaeology and retrospective dosimetry due to its pre-dose sensitization property. Various aspects of the peak, like its nature, defect centres involved, the impact of different stimuli and its application have been extensively studied. The main aims of this review are to (i) summarize briefly the work carried out on the various facets of this TL glow peak during the last four decades and (ii) identify the areas which need further attention in order to have a better understanding of the luminescence characteristics of this TL peak.      

多级石英晶体旋光光学滤波器的滤波特性

根据石英晶体的旋光色散特性,利用光学矩阵方法对多级石英晶体旋光光学滤波器的滤波原理进行了详细的理论分析,推导出多级石英晶体旋光光学滤波器的透射主峰波长和通带半宽度的计算公式.利用分光光度计对单级和多级石英晶体旋光光学滤波器的滤波特性进行了实验研究,结果表明单级和多级石英晶体旋光光学滤波器滤波特性与理论曲线一致.从理论和实验上证明了多级石英晶体旋光光学滤波器与单级相比通带半宽度得到了有效的压缩,且随滤波器级数的增大,压缩的程度也随之增大. 关键词： 光学滤波器 偏振 石英晶体 旋光色散     

Validation of quartz crystal rheometry in the megahertz frequency regime

The utility of the quartz crystal microbalance (QCM) as a high‐frequency rheometer operating at 15 MHz was demonstrated. High‐frequency data obtained from a series of rubbery materials were compared with results obtained from traditional dynamic mechanical analysis (DMA) at much lower frequencies. The high‐frequency data enable meaningful shift factors to be obtained at temperatures much further above glass‐transition temperature (T _g) than would otherwise be possible, giving a more complete picture of the temperature dependence of the viscoelastic properties. The QCM can also be used to quantify mass uptake and changes in viscoelastic properties during sample oxidation. The viscoelastic response spanning the full range of behaviors from the rubber to glassy regimes was found to fit well with a six‐element model consisting of three power‐law springpot elements. One of these elements is particularly sensitive to the behavior in the transition regime where the phase angle is maximized. The value of this quantity is obtained from the maximum phase angle, which can be obtained from a temperature sweep at fixed frequency, proving a means for more detailed frequency‐dependent rheometric information to be obtained from a fixed‐frequency measurement at a range of temperatures. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1246–1254     

石英晶体板非线性高频振动的拓展伽辽金法分析

针对考虑几何和材料非线性的石英晶体板厚度剪切振动和弯曲振动的方程组,利用扩展伽辽金法对该方程组进行转化和求解,分别获得了强烈耦合的厚度剪切振动模态和弯曲振动模态的频率响应关系,绘制了不同振幅比和不同驱动电压影响下的频率响应曲线图。数值计算结果表明可以选取石英晶片的最佳长厚比尺寸来避免两种模态的强烈耦合。驱动电压的变化将引起石英晶体谐振器厚度剪切振动频率的明显改变,必须将振动频率的漂移值控制在常用压电声波器件的允许值之内。扩展伽辽金法对石英晶体板非线性振动方程组的求解为非线性有限元分析和偏场效应分析奠定了基础。     

Temperature dependence of the cristobalite α-β inversion

The cristobalite - inversion has been studied using DSC on cristobalites produced by firing high purity quartz with and without addition of a mineraliser. If no mineraliser was used, the inversion temperatures and hysteresis on heating and cooling increased with firing temperature. Firing time had little or no effect on inversion temperature. When a mineraliser was used, the same general trend was observed with increases in firing time at low temperatures leading to splitting of the inversion peak. The amount of mineraliser added had little effect. Tridymite inversions were also observed. The results are explained in terms of the degree of order of the cristobalite structure.We are grateful for the award of an S.E.R.C. CASE award in conjunction with Specialist Refractory Services to SJS. Helpful discussions have been held with Mr. D. W. Bailey and Dr. P. Watkins.     

纳米氧化镱对熔融石英析晶动力学机制的影响

本文研究引入纳米氧化镱对熔融石英析晶机制及动力学过程的影响。通过X射线衍射仪(XRD)测试结果分析了纳米氧化镱的引入对熔融石英陶瓷析晶率的影响,采用动力学方法分析了纳米氧化镱的引入对熔融石英陶瓷析晶机制的影响,同时探讨了其等温析晶动力学过程。研究表明,熔融石英陶瓷的晶粒向二维兼有一维及三维的方式生长,引入纳米氧化镱的熔融石英陶瓷的晶粒则向二维兼有三维的方式生长;试样B和试样Y的析晶活化能E分别为874 kJ/mol和1 188 kJ/mol。在熔融石英陶瓷中引入纳米氧化镱能够大幅度减少SiO₂玻璃脱玻为方石英的“活性成核点”,增加玻璃表面结构稳定性,提高析晶活化能,大大降低熔融石英的析晶率。