齿形中心扩锥对旋流燃烧器气固流动影响的PDA试验研究

1前言旋流燃烧器依靠高温回流区做为稳定的热源，使煤粉气流及时着火并稳定燃烧，燃烧器单独组织燃烧，不互相影响，燃烧器区域的气固流动特性决定了燃烧器的性能。燃烧器的喷口结构对其气因流动特性有重要影响山。本文提出了齿形中心扩锥结构（如图l所示）。2实验方法及结果分析试验采用三维激光粒子动态分析仪（简称三维PDA），实验台系统主要由送风机、吸风机、给粉机、燃烧器模型、试验段、旋风分离器等组成，试验段为一竖直放置的筒体，直径为4800mm，燃烧器模型安装在简体上部中心位置，最外层扩口端部与筒体内壁平齐，沿射流流动方…     

圆管突扩气固两相流动湍流变动研究

采用PDA测量竖直向下圆管突扩流动中的气相与颗粒相运动参数,研究了小颗粒(55.2μm)、低雷诺数(1.98×10~4)的稀疏流动中湍流变动的规律。结果表明,在主流区和回流区中,颗粒均削弱气相脉动,而在下游则出现增强的现象,这是由于颗粒延缓了突扩流动的发展所致.在入口段的壁面剪切区域,湍流削弱幅度与平均速度梯度呈线性关系;由于壁面的限制,回流区内的剪切作用沿流动方向逐渐增强,使得相应的各横截面内气相脉动的最大值基本保持不变,同时整体脉动程度增强.     

Development of easy‐to‐use reverse‐phase liquid chromatographic methods for determining PRE‐084, RC‐33 and RC‐34 in biological matrices. The first step for in vivo analysis of sigma1 receptor agonists

Over the years there has been a growing interest in the therapeutic potential for central nervous system pathologies of sigma receptor modulators. The widely studied PRE‐084 and our compounds RC‐33 and RC‐34 are very potent and selective sigma 1 receptor agonists that could represent promising drug candidates for Amyotrophic Lateral Sclerosis (ALS). Herein, we develop and validate robust and easy‐to‐use reverse‐phase chromatographic methods suitable for detecting and quantifying PRE‐084, RC‐33 and RC‐34 in mouse blood, brain and spinal cord. An HPLC/UV/ESI‐MS system was employed for analyzing PRE‐084 and an HPLC/UV‐PDA system for determining RC‐33 and RC‐34. Chromatographic separations were achieved on Waters Symmetry RP₁₈ column (150 × 3.9 mm, 5 µm), eluting with water and acetonitrile (both containing 0.1% formic acid) in gradient conditions. The recovery of PRE‐084, RC‐33 and RC‐34 was >95% in all the considered matrices. Their limits of quantitation and detection were also determined. Validation proved the methods be suitable for separating tested compounds from endogenous interferences, being characterized by good sensitivity, linearity, precision and accuracy. A preliminary central nervous system distribution study showed a high distribution of RC‐33 in brain and spinal cord, with concentration values well above the determined limit of quantitation. The proposed methods will be used in future preclinical investigations. Copyright © 2015 John Wiley & Sons, Ltd.     

A simple taste analyzing system design for visual and quantitative analysis of different tastes using multi-array chemical sensors and pattern recognition techniques

In this paper, we describe design of a simple taste analyzing system using sensory system based on a multi-array chemical sensor (MACS) and personal digital assistant (PDA) for visual and quantitative analysis of different tastes using pattern recognition techniques. The sensory system is communicated with PDA, which has several interesting benefits for data analysis and display, via wireless using the Bluetooth. A various pattern recognition techniques are adapted including spider map, principal component analysis (PCA) and fuzzy C-means (FCM) algorithm to classify visually data patterns detected by the sensory system. The proposed techniques can be determined the cluster centers and membership grade of patterns through the unsupervised way. The membership grade of an unknown pattern, which does not shown previously, can be visually and analytically determined. Throughout the experimental trails, the taste analyzing system is demonstrated robust performance through data acquisition via wireless communication and visual and quantitative analysis of different tastes for the liquids. The system, which is implemented as a simple hand-held taste analyzing instrument, can be applicable to on-site taste monitoring.     

ZrO_2/rGO多层复合薄膜的构筑及其摩擦学性能研究

将层层自组装(LBL)技术与原位还原过程相结合在单晶硅片表面成功构筑了与基底结合牢固、性能优异的氧化锆/还原氧化石墨烯(ZrO2/rGO)多层纳米复合薄膜.试验中,引入了具有强附着性和还原性的物质-多巴胺,使得氧化石墨烯(GO)片的表面锚固和原位还原可以一步完成.另外,ZrO2粒子的表面组装通过简单、温和的溶液沉积过程来实现.结果证明:复合薄膜中rGO和ZrO2的引入以及多层结构的构筑赋予复合薄膜许多优异的性能.在不进行热处理的情况下,所构筑的ZrO2/rGO多层薄膜表现出优异的力学性能(硬度:11.54 GPa)和摩擦学性能(摩擦系数:0.12~0.17),可作为减摩抗磨涂层被用于微/纳机电系统(MEMS/NEMS)的表面保护和其他领域.     

Electrochemical Determination of Carbofuran in Tomatoes by a Concanavalin A (Con A) Polydopamine (PDA)-Reduced Graphene Oxide (RGO)-Gold Nanoparticle (GNP) Glassy Carbon Electrode (GCE) with Immobilized Acetylcholinesterase (AChE)

A new biosensor method was developed to determine residual carbofuran in tomatoes in a rapid and convenient fashion based on immobilizing acetylcholinesterase (AChE) on an electrode modified by concanavalin A (Con A)/polydopamine (PDA)-reduced graphene oxide (RGO)-gold nanoparticle (GNP) nanocomposites. The specific binding between Con A and AChE was investigated by the Ellman method and cyclic voltammetry (CV). The synthesis of nanocomposites was monitored by ultraviolet-visible absorption spectroscopy, scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). The results showed that, due to the specific binding and good electrical conductivity, the biosensor had 2.2 times higher bioactivity, leading to high sensitivity with a low Michaelis constant of 0.10?mM. Parameters that affect the response of the biosensor, such as the pH, enzyme loading, ionic concentration, and inhibition time, were optimized. When used for the detection of carbofuran, this biosensor showed a wide range of applicability from 5?µg/kg to 40?µg/kg with a detection limit of 0.012?µg/kg. In addition, the biosensor demonstrated good recovery values of 101% and 90% for 10?µg/kg and 100?µg/kg of the analyte, good stability, high repeatability, and a rapid detection time of 20?min for carbofuran in tomatoes, which provides significant advantages for future analysis.     

水果蔬菜中多种杀菌剂的基质固相分散液相色谱测定方法研究

采用基质固相分散(MSPD)代替液液分配和固相萃取,从蔬菜水果中提取、净化10种常用杀菌剂农药残留,用C18硅胶交联剂作为固相吸附剂,乙酸乙酯作为洗脱液,用HPLC/PDA和LC-MS进行分析检测。10种杀菌剂在0.5~5 mg/kg含量的添加回收率在65%~110%之间,相对标准偏差小于10%,使用HPLC、PDA和LC-MS的检出限分别在0.02~0.2 mg/kg和0.002~0.01 mg/kg之间。该方法节省溶剂,提取和净化一步完成,适用于新鲜水果和蔬菜中10种杀菌剂的残留分析。     

鳍片管绕流气固两相流动特性PDA测试及数值计算

1前言鳍片管束撞击式气固分离器是浙江大学提出的以鳍片管为分离元件（见图1）的一种循环流化床惯性气固分离装置，这种结构使得鳍片能被管束中的工质所冷却，因此对材质的要求不高，同时这种结构还有强化管束换热的效果。当气固两相流流经分离元件时，两相流撞击管束并在流动方向上多次转折后流出，由于颗粒的惯性，经过多次撞击和气流转向后，大部分颗粒将脱离主气流沿管束分离下来。系统的试验结果表明[1]，这种分离装置结构紧凑，具有较高的分离效率和较低的阻力，有一定的发展前途，在清华大学煤洁净燃烧国家重点实验室的资助下，我们…     

水平浓淡与上下浓淡煤粉燃烧方式气固混合特性的实验研究

本文针对四角切向燃烧锅炉燃用劣质煤时的稳燃及水冷壁高温腐蚀等问题,采用ＰＤＡ测量设备,对水平浓淡及上下浓淡两种煤粉燃烧方式下的气固两相混合规律进行了实验研究。实验表明,与上下浓淡煤粉燃烧方式相比,水平浓淡煤粉燃烧方式的气固两相流动特性使燃烧器在稳燃、低ＮＯｘ排放、防结渣、防高温腐蚀等方面具有优良的性能。     

Multiplicity-induced optimal gains of an inverted pendulum system under a delayed proportional-derivative-acceleration feedback

This paper studies the stabilization to an inverted pendulum under a delayed proportional-derivative-acceleration (PDA) feedback, which can be used to understand human balance in quiet standing. The closed-loop system is described by a neutral delay differential equation (NDDE). The optimal feedback gains (OFGs) that make the exponential decaying rate maximized are determined when the characteristic equation of the closed-loop has a repeated real root with multiplicity 4. Such a property is called multiplicity-induced dominancy of time-delay systems, and has been discussed intensively by many authors for retarded delay differential equations (RDDEs). This paper shows that multiplicity-induced dominancy can be achieved in NDDEs. In addition, the OFGs are delay-dependent, and decrease sharply to small numbers correspondingly as the delay increases from zero and varies slowly with respect to moderate delays. Thus, the inverted pendulum can be well-stabilized with moderate delays and relatively small feedback gains. The result might be understandable that the elderly with obvious response delays can be well-stabilized with a delayed PDA feedback controller.