掺杂对纳米SnO2甲醛敏感性能的影响

为了研发对甲醛有着良好敏感性能的材料,以锡粒和浓硝酸为原料,采用硝酸氧化法制备出前驱体,分别掺杂质量分数为7%的Li,Pb,Sb,Pd,并在600℃下灼烧.通过XRD、TEM等对产物进行表征,采用静态配气法测试其气敏性能.结果表明:SnO2纳米粉体中掺杂Pb元素可显著提高材料对甲醛的灵敏度和选择性,在3V工作电压下对浓度为5ppm(1ppm=10-6)的甲醛气体灵敏度达到24.539,响应时间为4s,恢复时间为5s.     

PID-200型光离子化有害气体监测仪的研制

研制了一种采用光离子化检测原理的有害气体监测仪。介绍了仪器的特点和技术措施。给出了主要技术指标,并与类似仪器做了对比。对浓度为0.29ppm的异丁烯样品测定11次,标准偏差为0.004ppm。     

XP系列高灵敏度可燃性气体浓度检测仪

最近由日本新电机有限公司研制了一种小形、轻量、高精度的可燃性气体浓度检测仪。该检测仪是采用高灵敏度的接触式气敏元件做为传感器,该传感器可以检测浓度非常低的可燃性气体。该机的检测灵敏度比一般的检测仪高十倍左右。而且,该机对可燃性气体的浓度能以10ppm为单位采用数字方式进行显示。     

采用富集方法提高气敏元件对甲醛的响应

用纳米SnO_2制作了旁热式甲醛气敏元件,测试了气敏元件对甲醛的响应,为了提高气敏元件对低浓度甲醛的响应,组装了一套富集装置.甲醛气体通过测试腔之前,先通过富集腔对其浓缩富集一段时间,然后加热活性炭使甲醛解吸出来,送入测试腔进行测试.测试了活性炭的最佳解吸温度为160 ℃.比较了富集前后气敏元件对甲醛的响应,富集前后气敏元件对20 ppm(1 ppm=10-6)甲醛的响应为分别为1.2和13.6.结果表明:富集后气敏元件对甲醛的响应明显提高.     

多参数动态气体校准仪的设计与实现

为产生ppb～ppm级微量浓度的高精准校准气体,设计了MFC-2000多参数动态气体校准仪,采用了具有强大功能模块的嵌入式微处理器MC9S12XDT512,完成了气体校准仪的结构及软硬件设计,提出了将臭氧发生器及光度计嵌入在仪器内部,实现了高精度的各种浓度校准气体的产生。试验结果表明,该仪器运行稳定,可靠性好,可以产生100 ppb～6 ppm级的臭氧、二氧化硫等标准气体,并可将产生的臭氧标气直接与NO零气反应产生特定浓度的NO2标气,为监测仪器的校准提供了更为简便的手段。     

基于红外吸收光谱的甲醛气体浓度检测

针对传统甲醛气体检测的不足,基于红外光谱吸收原理,采用差分吸收技术设计了甲醛气体浓度探测系统。该方法对检测的甲醛气体光谱值以及供电电压进行模数转换,通过光学检测系统对甲醛气体浓度进行检测,利用虚拟仪器LabVIEW软件实现数据采集、数据处理及数据存储与回放等功能。具有操作简单,界面直观,人机友好的特点,能对室内甲醛气体浓度进行实时检测。     

室内空气甲醛气体实时检测设计

本文研究了一种便携式室内甲醛气体实时检测系统。该系统以AT89S51单片机为核心，选用专用的甲醛传感器并设计了采集通道，通讯方式采用RS232串口，控制面板用LabVIEW开发，最后在控制面板上显示甲醛气体浓度曲线。     

基于单片机的车内空气质量监测系统的设计与开发

汽车内部空气质量是影响健康的重要因素,是最常用的出行工具。因此,研制一种便携式、可靠、简单、低成本检测器真正重要的是反映机器中污染物的种类和含量。本项目研究了苯乙烯和甲醛,确认了有害气体飞机的空气质量。这个仪器可以通过打开一个显示来显示。有害气体浓度过高的话,哪些气体超过了车辆标准。另外,以SD卡为储存,对不同时期有害气体浓度进行检测,为汽车空气质量分析提供了依据。     

原子吸收光谱法直接测定处理后电镀污水中的铜锌铅

国家标准规定,处理后电镀污水中的铜含量应小于1ppm,锌小于5ppm,铅小于1ppm。我厂用气浮法处理镀铜、镀铬以及电瓶充电时排出的污水。处理后的污水是否能达标排放,需要快速准确地测定其中的有关项目才能确定。火焰原子吸收法直接测定铜、锌尤其是铅的相对灵敏度低,满足不了要求。无火焰法、萃取富集等方法虽然能达到要求,但是一般厂矿不具备采用无火焰法的条件;萃取富集法操作麻烦,有机物喷射和燃烧时产生强烈的刺激性气体,污染环境,影响操作者的健康。本法将离子浓度浓缩6倍,测铅时扩展量程倍数,提高测定灵敏度,可以直接测定污水中小于1ppm的铜、锌、铅。一、实验部分     

基于非分光红外技术的低浓度SF6气体检测方法

文中介绍了一种基于非分光红外技术(NDIR)的高灵敏度的SF6气体浓度检测仪,测量范围可达0～50 ppm(1ppm=10-6),精度为0.1 ppm,由于传感器的特殊结构设计,使得其可以定点检测出SF6断路器或者GIS高压开关设备的微量泄露,对于设备的密封性检测有着实际的意义。     

Synthesis and characterization of a polyaniline/silver nanocomposite for the determination of formaldehyde

A polyaniline/silver nanocomposite was prepared through in situ polymerization and used to determine formaldehyde vapor. The prepared nanocomposite was characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The responses of the nanocomposite were much higher than using pure polyaniline. The nanocomposite exhibited good linearity versus gas concentration with a reproducible response. The limit of detection for the 25% silver nanocomposite was approximately 1.24 ppm.     

变压器油中气体拉曼光谱检测及信号处理方法

准确检测变压器油中溶解故障特征气体是诊断变压器运行状态的重要技术手段之一。论文基于拉曼光谱和腔长调制频率锁定原理,搭建了变压器故障特征气体频率锁定腔增强拉曼光检测平台,实现了H_2、CH_4、C_2H_2、C_2H_4、C_2H_6、CO、CO_2等七种故障特征气体的同时检测;1atm时,H_2、CH_4、C_2H_2、C_2H_4、C_2H_6、CO、CO_2的最小检测浓度实验值分别达到106、25、45、73、41、170、126(ppm)。频率锁定增强腔技术使最小检测浓度提高了约68倍。运用小波模极大值法对H_2的拉曼光谱检测信号进行了去噪处理,提出了基于包络线迭代法的光谱基线校正方法,校正后的光谱荧光背景残留减少,使气体拉曼光谱检测准确度提高了约2.95%,为变压器油中溶解故障气体同时准确检测提出了一种新方法。     

Airborne nondispersive infrared monitor for atmospheric trace gases

An airborne gas-filter correlation analyzer was designed and assembled to monitor atmospheric trace gases. Flight tests indicated that a methane version of this nondispersive infrared instrument performed properly while measuring CH(4) concentration profiles as small as 1 ppm from altitudes of 0.15 up to 1.2 km. A unique multiple chopping scheme was developed to simplify the gas-filter technique and to provide an easy mechanical nulling procedure. The single-beam rotating-cell optical system integrated with a multipass sampling cell and the signal processing circuit are described in detail.     

An evaluation of the accuracy and reliability of ethylene oxide diffusion badge monitors

Ethylene oxide (EO) gas is widely used in hospitals to sterilize certain moisture- and heat-sensitive materials. Based on scientific studies indicating its potential as a human carcinogen and mutagen, and the possible genotoxic, reproductive, neurologic, and sensitization hazards associated with EO exposure, the Occupational Safety and Health Administration has recently lowered the permissible exposure limit (PEL) from 50 ppm to 1 ppm as an 8-hour time-weighted average (TWA). This standard also established an "action level" of 0.5 ppm for an 8-hour TWA, below which employers are exempted from such requirements as periodic employee exposure monitoring or medical surveillance. These much lower concentrations of EO in air now place greater demands upon the analytical techniques used to monitor exposure of hospital personnel to EO. In this study, the capabilities of five EO diffusion monitors were examined in the TWA concentration range of 0.25-3.7 ppm. Both accuracy and precision were tested by exposing these devices simultaneously to measured concentrations of EO in a stainless steel exposure chamber. Temperature and humidity conditions were controlled, as was the flow rate of the gases across the sampling areas of the diffusion monitors. All of the monitors tested were sensitive enough to measure EO at the new PEL level, but in this laboratory investigation only one type of monitoring badge was able to meet the National Institute for Occupational Safety and Health criteria of +/- 25% overall system accuracy at the 95% confidence level in the exposure range of 0.5-2.0 X the OSHA PEL.     

纳米TiO2/ATP复合体的光催化活性

以凹凸棒石粘土（Attapulgite,缩写为ATP）为载体,通过酸性溶胶法制备纳米TiO2/ATP前驱体,再经过不同温度煅烧得到其复合体;采用甲醛为降解对象,研究表明,850℃以下煅烧得到的复合体,2h后甲醛的浓度已不足5mg/L,光催化降解率达到了98%以上,对甲醛的催化效果显著提高;在用量相同的情况下,复合催化剂与纯TiO2相比具有更高的光催化活性。     

大麦麸皮蛋白的提取及碱水解条件的研究

本实验是以大麦麸皮为原料,通过碱提酸沉工艺提取大麦麸皮蛋白,并优化了实验室提取条件。此外还探索了碱法水解大麦麸皮蛋白的工艺条件,为以后大麦蛋白的更好利用提供了一些依据。通过单因素实验,以固液比、PH值、时间进行三因素三水平正交实验,通过考马斯亮兰法对蛋白质含量进行测定。结果表明蛋白提取率为10％左右,最佳工艺条件：固液比1：15,PH=12,水解温度40℃。在碱法水解蛋白工艺中,以水解温度、时间、加碱量为单因素考察,运用甲醛法对水解度的测定结果表明该工艺的水解度大约为30％左右。并且通过凝胶层析法考察了不同水解时间的分子量变化,水解产物主要是对应分子量分别在31500Da和100—200Da左右的小分子物质。     

Influence of aceto acetic esters and di-carboxylic acid esters on diesel fuel lubricity

This paper presents the impact of acetoacetic esters and di-carboxylic acid esters on the lubrication properties of automotive diesel. Three alkyl acetoacetates and seven di-carboxylic esters were used as lubricating additives on two low sulfur diesel fuels, at seven different concentrations of 50, 100, 500, 750, 1000, 1500 and 2000 ppm. Tribological experiments carried out on the high frequency reciprocating rig (HFRR) showed that only two of the three acetoacetic esters used, provide satisfactory mean wear scar diameter (WS 1.4) of less than 460 μm, at the concentration level of 750 ppm. In the case of di-carboxylic acid esters, the effective concentration was 500 ppm or higher.     

天然气中稀有气体浓度与同位素比值联测技术及应用

研制了天然气中稀有气体纯化富集的前处理装置,并与稀有气体同位素质谱仪联用,构建了气体样品中He、Ne、Ar、Kr、Xe浓度和同位素比值联测的分析系统,通过1次进样可得到5种稀有气体组分浓度和同位素比值的共计23个数据。稀有气体纯化效果可达99.9%,质谱分析He、Ne、Ar、Kr浓度的相对标准偏差小于10%,同位素比值分析的标准偏差普遍小于5%。将该方法用于分析塔里木盆地天然气样品,得到了丰富的地质地球化学信息,通过稀有气体分布特征进一步明确了塔河和雅克拉气田区域构造活动的差异,以及二者气源岩特性的不同。