Electrochemical Micromachining on Different Types of GaAs by Confined Etchant Layer Technique

应用约束刻蚀剂层技术(CElT)对gAAS进行电化学微加工.研究了刻蚀溶液体系中各组成的浓度比例、gAAS类型、掺杂以及阳极腐蚀过程对gAAS刻蚀加工过程的影响.循环伏安实验表明,br-可以通过电化学反应生成br2作为刻蚀剂,l-胱氨酸可作为有效的捕捉剂.CElT中刻蚀剂层被紧紧束缚于模板表面,模板和工件之间的距离小于刻蚀剂层的厚度时,刻蚀剂可以对gAAS进行加工.利用表面具有微凸半球阵列的导电模板,可以在不同类型gAAS上加工得到微孔阵列.实验结果表明:在相同刻蚀条件下,gAAS的加工分辨率与刻蚀体系中各组分的浓度比例有关,刻蚀结构的尺寸随着刻蚀剂与捕捉剂浓度比的增加而增大;在加工过程中,P-gAAS相对于n-gAAS和无掺杂gAAS受到阳极氧化过程的影响较为显著,P-gAAS表面易生成氧化物层,影响电化学微加工过程.X射线光电子能谱(XPS)和极化曲线实验也证明了这一点.The confined etchant layer technique (CELT) was applied to electrochemical micromachining on different types of GaAs (p-type, n-type, undoped).Cyclic voltammetry curves showed that the etchant bromine was generated on the mold and L-cystine was thus used as an efficient scavenger to react quickly with the etchant.Therefore, the etchant was confined very close to the surface of the mold and it etched the workpiece of GaAs when the distance between the mold and workpiece was less than the thickness of the confined etchant layer.An array of concave microstructures was fabricated on different types of GaAs by CELT using a mold with an array of convex hemispheres.Several factors including the concentration ratio between the etchant and the scavenger, types of GaAs, and anodic oxidation during the process of CELT were studied.Experimental results showed that the resolution of electrochemical micromachining increased when the thickness of the confined etchant layer decreased.During the microfabrication process, anodic dissolution affected the electrochemical micromachining of p-type GaAs much more than that of the other two types of GaAs.The oxide layer on p-GaAs had a strong influence on electrochemical micromachining.X-ray photoelectron spectroscopy (XPS) and polarization curves also proved the existence of the oxide layer on p-GaAs.国家自然科学基金(20873112);国家光电子晶体材料工程技术研究中心开放课题(2005DC105003)资助项目---

Quantitative determination of arachidonic acid from microbial oil by gas chromatography

建立了快速、灵敏测定微生物油脂中花生四烯酸(AA)含量的气相色谱法(gC)。采用HP-InnOWAX毛细管柱,氢火焰离子化检测器(fId),优化了分析花生四烯酸酯化产物的色谱条件。结果表明:花生四烯酸甲酯(AA-ME)在0~1.00 Mg/Ml范围内具有较好线性,相关系数为0.999 6,检测限为0.000 5 Mg/Ml,相对标准偏差(rSd)为1.49%,回收率在95.86%~105.32%;花生四烯酸乙酯(AA-EE)在0~1.23 Mg/Ml范围内线性良好,相关系数为0.999 9,检测限为0.003 0 Mg/Ml,rSd为0.60%,回收率在97.79%~103.61%。A gas chromatography(GC) method for the determination of arachidonic acid(AA) in microbial oil was developed.Capillary column HP-INNOWAX with FID was used for detection.The parameters for analyzing esterfied AA were optimized and the method established was proved to be accurate and precise.The linearity range for methyl arachidonate was 0-1.00 mg/mL and the linear correlation coefficient was 0.999 6,the detection limit was 0.000 5 mg/mL,the relative standard deviation(RSD)was 1.49% and the recovery rate was 95.86%-105.32%.The linearity range for ethyl arachidonate was 0-1.23 mg/mL and the linear correlation coefficient was 0.999 9,the detection limit was 0.003 0 mg/mL,the RSD was 0.60% and the recovery rate was 97.79%-103.61%.厦门海洋研究开发院共建项

Electrochemical Micromachining on Different Types of GaAs by Confined Etchant Layer Technique

The confined etchant layer technique (CELT) was applied to electrochemical micromachining on different types of GaAs (p-type, n-type, undoped). Cyclic voltammetry curves showed that the etchant bromine was generated on the mold and L-cystine was thus used as an efficient scavenger to react quickly with the etchant. Therefore, the etchant was confined very close to the surface of the mold and it etched the workpiece of GaAs when the distance between the mold and workpiece was less than the thickness of the confined etchant layer. An array of concave microstructures was fabricated on different types of GaAs by CELT using a mold with an array of convex hemispheres. Several factors including the concentration ratio between the etchant and the scavenger, types of GaAs, and anodic oxidation during the process of CELT were studied. Experimental results showed that the resolution of electrochemical micromachining increased when the thickness of the confined etchant layer decreased. During the microfabrication process, anodic dissolution affected the electrochemical micromachining of p-type GaAs much more than that of the other two types of GaAs. The oxide layer on p-GaAs had a strong influence on electrochemical micromachining. X-ray photoelectron spectroscopy (XPS) and polarization curves also proved the existence of the oxide layer on p-GaAs.National Natural Science Foundation of China [20873112]; Fund of National Engineering Research Center for Optoelectronic Crystalline Materials of China [2005DC105003

Methyl Esterification of Arachidonic Acid in Microbial Oil

作者简介：董宏祯(1988 —)，男，硕士研究生，研究方向为天然产物化学。E-mail：[email protected] 通信作者：许建中(1954 —)，男，高级工程师，本科，研究方向为生物化工。E-mai l：[email protected][中文文摘]以微生物油脂为原料,对其中花生四烯酸的甲酯化方法进行筛选和优化。在确定合适的花生四烯酸甲酯化方法基础上,考察酯化温度、酯化时间、催化剂体积分数及搅拌转速对花生四烯酸酯化效果的影响。结果表明:酯化温度80℃、酯化时间8h、浓硫酸体积分数2.0%、转速400r/min时,花生四烯酸甲酯质量分数达到37.75%,产率达到91.54%。甲酯化后的花生四烯酸沸点较低,适用于分子蒸馏。[英文文摘]In order to maximize arachidonic acid methyl ester production,the methyl esterification of microbial oil was optimized with respect to temperature,reaction time,catalyst(concentrated sulfuric acid) dosage and agitation speed using one-factor-a-at-a-time combined with orthogonal array design method.The highest yield of 91.54% was achieved after 8 h of reaction at 80 ℃ and an agitation speed of 400 r/min under the catalysis of 2.0% concentrated sulfuric acid.The obtained product contained 37.75% arachidonic acid methyl ester and its boiling point was lower than before the reaction, facilitating molecular distillation.厦门海洋研究开发院共建项目; 福建省海洋与渔业厅科技重点项目([2009]2-10);厦门市科技计划项目(3502Z20112005);福建省2010年第二批产业技术开发项目(5012060403

Value Analysis determines when and how to strive

优化努力的分配,最小化努力成本和最大化收益是各个领域的关键问题。本文梳理了基于努力的决策(effort-based decision-making)的理论与实证研究,讨论了努力的两面性：固有成本和潜在价值。通过拓展控制期望价值理论(Expected Value of Control, EVC),本研究探讨了影响努力的非社会与社会因素。探索人们何时以及如何付出努力的计算神经机制,有利于理解与促进社会互动中的努力行为,以及为干预精神疾病中动机缺失症状提供参考。</p

Vehicle License Plate Recognition Method Based on Active Contour Model

提出了一种识别机动车辆牌照的算法。该算法首先利用车牌的纹理特征和区域形状特征检测车牌区域。为提高区域检测的正确性,利用新的改进的主动轮廓模型,利用先验知识确定精确的车牌边界。在精确确定车牌区域基础上,可以准确切割出车牌中的字符,从而提高识别率。A license plate recognition method is presented.It utilizes the texture character and region shape character of a plate to extract the initial region. To improve the region extraction accuracy, propose a novel method based on advanced active contour model for employing the apriori knowledge of the license plate. Because of the accuracy of the plate region extraction, the character can be extracted exactly from the plate region.It can improve the accuracy rate of the characters recognition

Application of Intelligent Algorithm to Vehicle License Plate Recognition

文章介绍了利用车牌的纹理特征和区域形状特征检测车牌区域情况。为提高区域检测的正确性,利用新的改进的主动轮廓模型,利用先验知识确定精确的车牌边界。在精确的车牌区域中切割出车牌中的单个字符,最后利用支持矢量机对字符进行分类识别。This paper presents a license plate recognition method to extract the initial region by utilizing the texture character and region shape character of a plate. To improve the region extraction accuracy, the paper uses newly-improved active contour models and a priori knowledge to decide accurate plate border. Because of the accuracy of the plate region extraction, the character can be extracted exactly from the plate region. Finally, support vector machine is used to recognize the characters

Design and Analysis of General File System in Embedded Multi-media Application

随着嵌入式多媒体技术的日趋发展,越来越多的多媒体娱乐设施已经用于家用起居和娱乐场所。文中旨在提出和构建一个通用的、移植性强的、针对嵌入式系统上多媒体应用的文件系统来管理多媒体数据,提高数据的存取效率和存储设备的空间利用率,从而获得良好的视听效果。通过分析FAT文件系统的性能,以及比较在PC机和嵌入式系统上应用的优缺点,并结合多媒体数据本身的特殊性以及嵌入式的具体应用环境,对其进行改进,以实现优越的性能来适应嵌入式多媒体的应用。With the gradual development of multi-media techniques,more and more multimedia facilities are put into use in home appliances and recreational spots.This article intends to propose and construct a general file system to manage multimedia datum to increase the efficiency of access and storage, which is transplantable and steady in embedded systems.After comparing the advantages and the disadvantages in PC systems with those of in embedded systems by analyzing and comparing the performance of FAT file system, the author tries to improve file systems in embedded systems to adapt the entitative multimedia applications with reference to the particularities of multimedia datum and the environments of embedded system