High-frequency micromechanical columnar resonators

Abstract

High-frequency silicon columnar microresonators are fabricated using a simple but effective technological scheme. An optimized fabrication scheme was invented to obtain mechanically protected microcolumns with lateral dimensions controlled on a scale of at least 1 μm. In this paper, we investigate the influence of the environmental conditions on the mechanical resonator properties. At ambient conditions, we observed a frequency stability δf/f of less than 10^?6 during 5 h of operation at almost constant temperature. However, varying the temperature shifts the frequency by approximately ?173 Hz °C^{? 1}. In accordance with a viscous damping model of the ambient gas, we perceived that the quality factor of the first flexural mode decreased with the inverse of the square root of pressure. However, in the low-pressure regime, a linear dependence was observed. We also investigated the influence of the type of the immersing gas on the resonant frequency.     

微柱高效液相色谱法测定烟草样品中植物色素的研究

通过微柱高效液相色谱法测定烟草样品中的植物色素;用 90%丙酮震荡浸提烟草样品中的色素,提取液经WatersSep Park-C18固相萃取小柱预分离和富集,以WatersXterraTMRP18 (1. 0×50mm, 2. 5μm)色谱柱为固定相, (1+1)甲醇异丙醇溶液-水梯度为流动相,烟叶中的叶绿素 a、叶绿素 b、β 胡萝卜素、叶黄素、新叶黄素、紫黄质和脱镁叶绿素等色素分别在其最大吸收波长监测下分离提取,色谱峰面积定量。该方法标准回收率95% ~105%, RSD为 1. 6% ~2. 5%。将其用于烟草中天然色素含量的测定,结果令人满意。     

Experimental Tests and Modelling of an Electrodeionization Cell for the Treatment of Dilute Copper Solutions

The paper presents the results of experimental and theoretical investigations of an electrodeionization process for the removal of metal cations from dilute solutions. The ability of this technique to treat 100 ppm copper solutions using cationic membranes and ion‐exchange resins between the membranes was studied. Fair abatement yields were obtained in the 100 mm high resin bed in long‐term runs, and solutions of an appreciable copper ion concentration could be produced in the cathode chamber. The process capacity was limited by significant deposition of copper at the cathode, non‐even distribution of current density, and side‐diffusion to the anode chamber. Additional tests were then carried out using a 15 mm resin bed. The more even current distributions allowed the effect of the resin stiffness and the current density on the removal yield to be thoroughly observed. Steady‐state operation of the resin bed was modelled using generalized expressions of the various transport rates. Results of the model clearly showed the significance of solid‐liquid interactions on the transport processes.     

高纯稀土氧化物中的非稀土杂质的测定流动注射微柱预富集ICP-AES法

利用自合成的碳硅凝胶为吸附材料,以铜试剂［二乙基二硫代氨基甲酸钠（ＮａＤＤＴＣ）］为柱前衍生化试剂。在优化的实验条件下,于ｐＨ４．６的缓冲介质中在线预富集Ａｌ（Ⅲ）,Ｃｒ（Ⅵ）,Ｃｕ（Ⅱ）,Ｆｅ（Ⅲ）,Ｐｂ（Ⅱ）,Ｖ（Ⅴ）和Ｚｎ（Ⅱ）．采用停流技术洗脱,富集倍数可达８．１～１２．６倍,检出限为ｎｇ／ｍＬ级。对高纯氧化铕（Ｅｕ２Ｏ３）中的非稀土杂质进行测定,可避免大量稀土基体对测定的干扰。     

微柱高效液相色谱法测定苦荞中芦丁的研究

研究了用微柱高效液相色谱法测定苦荞中芦丁的方法。苦荞中的芦丁用 80 %甲醇加热回流提取 ,以WatersXterraTMRP1 8( 1.0× 5 0mm ,2 .5 μm)色谱柱为固定相 ,1%的醋酸和甲醇为流动相 ,在该色谱条件下 ,苦荞中主要的芦丁在 1.0min内可达到基线分离 ,用紫外二极管矩阵检测器检测 ,方法可用于苦荞中的芦丁的测定 ,结果满意。     

Technical Note — Analysis of Beer Aroma Compounds by Solid‐phase Microcolumn Extraction

Due to their low dead volumes, microcolumns with Tenax TA coupled to a capillary column in the modified GC inlet allow analysis of a broad range of compounds (from acetaldehyde to 2‐phenylethanol) in a single sample run. In this study, a micro‐column was filled with 10 mg of Tenax TA. Chromatograms showed well‐resolved peaks even at the beginning of the run. Static headspace was used to pre‐concentrate the compounds. The method is rapid, simple and inexpensive.     

三乙烯四胺型螯合树脂微柱分离富集-火焰原子吸收光谱法测定地质样品中痕量银

用新合成含硫三乙烯四胺型螯舍树脂填充微型吸附柱，建立了螯合树脂微柱分离富集一火焰原子吸收光谱法测定地质样品中痕量银的方法。研究了螯合树脂微柱的吸附性能及影响吸附的因素，用酸性硫脲作洗脱剂，以峰面积检测，测定Ag(Ⅰ)的线性范围为0.02～1．0μg／mL，相对标准偏差为2．3％(n=3)，检出限为0．005μg／mL，灵敏度提高20倍，螯合树脂微柱可重复利用。用于地质样品中痕量银的测定，结果满意。     

微柱高效液相色谱技术在中草药质量监控中的应用进展

介绍了微柱高效液相色谱(MHPLC)技术在中草药质量监控中的应用现状,简要论述了微柱高效液相色谱技术及其联用技术。     

基于导电涂层微结构TPU柔性传感器的制备和性能

将具有表面微结构和平整的热塑性聚氨酯（TPU）传感基片封装成压阻型柔性压力传感器，其中前者（尺寸为10 mm×10 mm）的表面喷涂不同质量（0.02、0.05、0.1 g）的多壁碳纳米管（MWCNTs），并对微结构柔性传感基片表面形貌及传感器性能进行了表征和分析。结果表明，微结构传感基片表面上微柱顶面形成一定厚度的MWCNTs层，层内MWCNTs形成网络；喷涂较高MWCNTs质量时，传感器具有较高的灵敏度和较低的检测限，这归因于压力所致MWCNTs的网络搭接程度和传感基片间接触面积的增加量较大；喷涂0.1 g MWCNTs时，传感器的灵敏度为0.143 kPa^-1（0~3 kPa），检测限低至100 Pa，在较宽压力范围内（3~200 kPa）仍有一定的压阻响应，能在4 000次的循环压缩/释放测试（峰值压力约200 kPa）中保持稳定的压阻响应，且可准确检测典型人体运动所产生的压阻响应，具有应用于智能穿戴领域的潜能。