低应力PECVD SiC晶圆级薄膜封装新技术

为了解决MEMS封装过程中易对微致动件造成损伤的问题,提出了一种低成本、与CMOS工艺兼容的晶圆级薄膜封装技术,用等离子体增强化学气相淀积(PECVD)法制备的低应力SiC作为封装和密封材料。此材料的杨氏模量为460 GPa,残余应力为65 MPa,可使MEMS器件悬浮时封装部位不变形。与GaAs,Si半导体材料相比,SiC具有较佳的物理稳定性,较高的杨氏模量等性能优势。将PECVD薄膜封装技术用于表面微结构和绝缘膜上Si(SOI)微结构部件(如射频开关、微加速度计等)封装中,不仅减小了封装尺寸,降低了芯片厚度,简化了封装工艺,而且封装芯片还与CMOS工艺兼容。较之晶圆键合封装方式,此晶圆级薄膜封装成本可降低5%左右。     

京郊历史文化村落存续现状的多维探析——以北京东郊为例

北京郊区有着广泛分布的历史文化村落,是北京历史文化资源的重要组成部分。然而,在快速的城市化发展进程及近年来的"新农村建设"浪潮中,这些村落正面临着严重的存续危机。从空间维度、政策维度、经济维度三个层面对北京东郊历史文化村落的存续现状进行研究,可为后续各项保护措施的制定提供决策依据。     

苹果酒发酵过程中酵母对氨基酸利用的研究

对酵母J00的氨基酸利用特性进行了研究，确定出该酵母对各种氨基酸和NH_4~+的需要范围。通过调整苹果浓缩汁中的氨基酸含量，并分析氨基酸对酵母发酵代谢产物的影响，发现当果汁中氨基酸及NH_4~+的组成为：NH_4~+(120mg／L)、组氨酸(30mg／L)、苯丙氨酸(30mg／L)、缬氨酸(35mg／L)、异亮氨酸(30mg／L)、亮氨酸(10mg／L)、天门冬氨酸(160mg／L)、苏氨酸(1000mg／L)、谷氨酸(45mg／L)、甘氨酸(5mg／L)、丙氨酸(25mg／L)、蛋氨酸(15mg／L)、酪氨酸(15mg／L)、赖氨酸(45mg／L)、精氨酸(25mg／L)、天门冬酰胺(30mg／L)时，各种氮源的比例比较合适，使酵母发酵过程较优，可增加乙醇产率，提高总糖利用率，同时可以达到降低高级醇生成量的目的。     

油田措施配置随机动态目标规划

针对油田开发实际中存在的随机现象和动态特征,建立了油田措施的目标随机动态规划模型,并采用具有擅长全局搜索和高度鲁棒性特点的遗传算法进行求解。应用结果表明,该模型给出了各项稳产措施的增油量 、增水量及生产费用,使措施配置更能反映实际生产动态。该方法是油田开发方案调整的极为有力的工具。     

Determination of Trace Nickel in Hydrogenated Cottonseed Oil by Pressurized Bomb Acid Digestion and Graphite Furnace Atomic Absorption Spectrometry Detection

A pressurized polytetrafluoroethylene (PTFE) bomb method for the digestion of trace nickel in hydrogenated cottonseed oil prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS) has been developed. Currently, the methods outlined in United States Pharmacopeial 28 (USP28) and British Pharmacopeial (BP2003) methods are recommended as the official methods for analyzing nickel in hydrogenated cottonseed oil. However, when using these methods, the samples were easily tarnished during sample pretreatment when using a silica crucible. In contrast, when using a platinum crucible, hydrogenated cottonseed oil acting as a reducing material may react with the platinum and destroy the crucible. In order to avoid the tarnish with a silica crucible and the risk when using platinum, the technology of a pressurized PTFE bomb method was applied in the digestion of nickel in hydrogenated cottonseed oil. The results showed that hydrogenated cottonseed oil can be digested completely by the optimal combinations of HCl (0.1 mL) and HNO₃ (0.5 mL). The digested solution was investigated using graphite furnace atomic absorption spectrometry.     

GC/MS Method for the Determination of Adipate Plasticizers in Ham Sausage and Its Application to Kinetic and Penetration Studies

ABSTRACT:  A GC/MS method was developed and successfully validated for the determination of adipate plasticizers in ham sausage migrated from polyvinylidene chloride (PVDC) packaging film. The sample pretreatment includes liquid extraction, solvent evaporation, and reconstitution before and after solid phase extraction (SPE). For the 5 adipate plasticizers studied, the SPE process with Oasis MAX cartridge showed an extraction efficiency from 85.7% to 106%, and the calibration curves are all linear in the range of 5 to 1000 ng/g with correlation coefficients greater than 0.998. The method proved to be accurate and precise; the average intraday recovery ranges from 85.4% to 114.6% with a %CV value from 2.5 to 11.3, and the average interday recovery from 83.6% to 118.5% with a %CV value from 2.8 to 15.6, respectively, for the adipate plasticizers. The method is sensitive and was effectively applied in the kinetic and penetration studies of the adipate plasticizers migrating from food-grade PVDC packaging film into ham sausage. The experimental data showed that approximately 6.8% of dibutyl adipate (DBA) in the packaging film migrated into the ham sausage in 4 mo and the migration reached the innermost portion of the sausage in 6 mo.     

Facile nano‐free electrochemiluminescence biosensor for detection of sulphamethoxazole via tris(2,2′‐bipyridyl)ruthenium(II) and N ‐methyl pyrrolidone recognition

The electrochemiluminescence (ECL) system based on the ruthenium complex has become a powerful tool in the field of analytical chemistry. However, the non‐aqueous ECL luminescence system, which does not involve complex nano‐modification, has not been widely used for the determination of analytes. In this study, N ‐methyl pyrrolidone was selected as the solvent, and it could also act as a co‐reactant of Rubpy32+. Based on this, a simple ECL system without nanomaterials was established. Strong ECL was generated. Furthermore, a quenching effect between the excited state of Rubpy32+ and sulphamethoxazole (SMZ) was observed. Based on this, a sensitive ECL sensor for detecting SMZ is constructed. A linear relationship between ECL signal quenching intensity (ΔI) and the logarithm of SMZ concentration (log C) in the concentration range of 1 × 10⁻⁷ –1 × 10⁻⁵ mol/l is obtained. The limit of detection is as low as 3.33 × 10⁻⁹ mol/l. The method has been applied to the detection of SMZ in tap water samples with different concentration levels with satisfactory results, and the recovery was 95.3–102.6%.Inspec keywords: biosensors, electrochemical sensors, electroluminescence, chemiluminescence, organic compounds, electrochemistryOther keywords: ruthenium complex, analytical chemistry, nonaqueous ECL luminescence system, complex nanomodification, quenching effect, ECL signal quenching intensity, ECL sensor system, nanofree electrochemiluminescence biosensor system, sulphamethoxazole detection, tris(2,2′‐bipyridyl)ruthenium(II), N‐methyl pyrrolidone recognition, analyte determination, nanomaterials, SMZ concentration detection     

Nitric oxide-synthesising neurons in the central subnucleus of the nucleus tractus solitarius provide a major innervation of the rostral nucleus ambiguus in the rabbit

We describe an intramedullary nitric oxide synthase (NOS) neural pathway that projects from the nucleus tractus solitarius (NTS) to the rostral nucleus ambiguus (NA) in the rabbit. With the use of NADPH diaphorase histochemistry and NOS immunohistochemistry, a compact group of NOS-positive perikarya was identified in the central subnucleus of the NTS dorsomedial to the tractus solitarius and rostral to the obex. A dense network of NOS terminals was seen in the rostral NA. We investigated whether NOS terminals in the NA derive from NOS perikarya in the central NTS and whether the central NOS pathway links esophageal afferents and efferents. In some rabbits, the central NTS was unilaterally lesioned. In others, Phaseolus vulgaris-leucoagglutinin (PHA-L) was injected into the central NTS, or cholera toxin-gold was injected into the NA, or cholera toxin-horseradish peroxidase (HRP) was injected into the wall of the esophagus. The medulla was subsequently processed to demonstrate PHA-L, cholera toxin-gold, HRP, and NOS reactivity. Seven days after the NTS lesion, we observed a marked decrease in the density of NOS terminals in the ipsilateral NA. After injection of PHA-L into the central NTS, a dense group of PHA-L fibres was seen in the rostral NA, principally ipsilaterally. Afferent fibres from the esophagus were found around the NOS cell bodies in the central NTS, and many of these NOS neurons were double labeled with cholera toxin-gold after injection of this tracer into the NA. NOS terminals were found around NA neurons that were retrogradely labelled from the esophagus. We conclude that the NOS neurons in the central NTS act as interneurons in a central pathway connecting esophageal afferents and efferents.     

基于经验模态分解的转子启动波德图绘制

提出利用经验模态分解的方法来绘制转子启动的波德图。此波德图能够准确地体现转子启动的动态信息,从而克服了手工绘制波德图时由于间断采样使得数据在临界转速不准确的缺点。同时,针对经验模态分解的边缘效应,采用了一种基于等斜率的新方法,即增加极值点的斜率和临近极值点的斜率相等,与其它的边缘值处理方法相比较,该方法不仅利用了信号的内部特征,而且拥有计算简单的优点。     

基于VMD和MP算法的旋转机械故障特征提取

旋转机械故障振动信号为不平稳、非线性而且信噪比低的多分量信号,故障特征很难提取。小波分析方法受限于小波基和分解层次的选取,经验模态分解（EMD）等自适应分解方法存在模态混叠和虚假分量的问题,应用在旋转机械故障提取上容易误判。提出了利用匹配追踪算法（MP）改进变分模态分解(VMD)的故障诊断方法。通过构建合适的仿真信号仿真和对实测信号的仿真,验证了该方法的可行性和实用性。