稀土杂质对纳米BaTiO3湿敏性能的影响

分别研究了钠盐和稀土杂质对BaTiO3纳米晶材料湿敏元件电学性能的影响,结果表明钠盐和稀土金属氧化物都能降低湿敏元件的电阻和湿滞.掺钠盐的湿敏元件电阻较低,但长期稳定性不如掺稀土金属氧化物的湿敏元件.初步分析了掺杂影响湿敏材料特性的机理.     

TiO2基陶瓷湿敏元件的研究和发展

TiO2基湿敏陶瓷是一类十分重要的湿敏陶瓷,应用十分广泛.本文综述了TiO2基陶瓷湿敏元件的研究和发展.重点介绍了7种TiO2基陶瓷湿敏元件的材料配方、制备工艺、湿敏性能及研究进展.     

TiO2基陶湿敏元件的研究和发展

ＴｉＯ２基湿敏陶瓷是一类十分重要的湿敏陶瓷,应用十分广泛。本文综述了ＴｉＯ２基陶瓷湿敏元件的研究和发展,重要介绍了７种ＴｉＯ２基陶瓷湿敏元件的材料配方、制备工艺、湿敏性能及研究进展。     

高分子电阻型湿敏元件的复阻抗谱测试与分析

测量了高分子电阻型湿敏元件在低湿和高湿的复阻抗谱,利用复阻抗谱法求出了湿敏元件的体电阻,由此分析了湿敏元件的导电机理。     

用Mssbauer谱研究Zn_2SnO_4的湿敏机理

本文用 Mssbauer 谱学方法,对半导体陶瓷 Zn_2SnO_4的湿敏机理做了分析,得出结论:Sn 原子对Zn_2SnO_4的湿敏机理是有贡献的,Zn_2SnO_4湿敏机理是电子离子混合型传导,作为湿敏机理分析方法,M(?)ssbauer 谱是比较合适的。     

电容式多孔硅湿敏元件初探

阐述了电容式多孔硅湿敏元件的制备方法,并且研究了它的湿敏特性.实验结果表明:电容式多孔硅湿敏元件的电容值随着湿度的增大而显著增大,在中湿区(43.16%RH～68.86%RH)容湿特性为线性,而且有较小的湿滞.     

陶瓷湿敏元件的长期稳定性问题及改进措施

陶瓷湿度传感器是湿度传感器的重要发展方向。改善陶瓷湿敏元件的长期稳定性是一项重要的研究课题。本文详细分析了湿敏陶瓷的微观结构和感温机理,评述了引起陶瓷湿敏元件性能漂移的因素和机理,以及改善陶瓷湿敏元件长期稳定性的有效措施。     

气象用湿敏电容传感器的稳定性测试与分析

为研究湿敏电容传感器的稳定性特征,利用14支湿敏电容传感器静态测试数据,用误差年漂移量定量表征湿敏电容传感器的稳定性,并对误差年漂移量的变化规律及影响因素进行分析。结果表明,湿敏电容传感器的稳定性受温度、温度和湿度的交互作用以及厂家制造水平的影响,低温时稳定性较差;室温时稳定性随湿度升高而降低。经过一年的使用,78.6%的湿敏电容传感器无法满足技术指标要求。     

单体固化特性对光热敏微胶囊显影密度的影响

利用界面聚合技术制备了以不同单体为囊芯的新型感光材料光热敏微胶囊.借助于傅里叶红外光谱及原子力显微技术对不同单体的双键交联固化及固化产物的表面形貌进行了分析,利用热显影打印技术检测了光热敏微胶囊显影密度随曝光时间的变化.实验结果表明,不同单体的双键交联固化速度主要与单体官能度有关,并且单体固化产物的表面形貌与单体的双键...     

纳米SnO_2及分子筛封装纳米SnO_2簇的湿敏性能研究

本文以液相法制备的纳米ＳｎＯ２微粉和分子筛封装的纳米ＳｎＯ２簇微粉为原料，采用涂膜法制作成湿敏元件，并且分别对这两种元件进行了湿敏性能的测试。研究表明纳米ＳｎＯ２微粉和分子筛封装的纳米ＳｎＯ２簇微粉，其湿敏元件灵敏度明显高于普通ＳｎＯ２微粉，阻湿线性关系良好，具有较好的湿敏性能。     

Generating Sensor Diversity through Combinatorial Polymer Synthesis

A new approach for rapid, simple generation of uniquely responding sensors for use in polymer-based sensor arrays has been developed. Polymerization reactions between different combinations of two starting materials have been found to lead to many new, unique sensors with responses not simply related to the proportion of the starting materials. This approach is demonstrated in two ways: (a) the use of discrete polymer sensing cones each comprised of a specific monomer combination and (b) the fabrication of a gradient sensor, containing all combinations between the starting and ending monomer concentrations. Gradient sensors were fabricated using two different binary monomer systems, with both systems showing regions of broadly diverse fluorescence responses to organic vapor pulses.     

Paraoxon imprinted biopolymer based QCM sensor

In this study, a novel quartz crystal microbalance (QCM) based on the modification of paraoxon imprinted polymer (TCM-Cd(II)-paraoxon) film onto a quartz crystal sensor has been developed for the determination of paraoxon. The sensor is based on a molecular imprinted polymer (MIP) which can be synthesized using paraoxon as a template molecule, Thiourea Modified Chitosan-Cd(II) (TCM-Cd(II)) as the metal-chelate monomer, ephychlorohydrin as a crosslinking agent. The MIP particles have been characterized by FTIR measurements and QCM sensor has characterized using AFM and ellipsometer. The performance of the paraoxon imprinted sensor has indicated that a selective and sensitive paraoxon imprinted sensor could be fabricated. The sensor is able to discriminate paraoxon in solution owing to the specific binding of the imprinted sites. The obtained paraoxon imprinted sensor has 0.02–1 μM linear range and low detection limit (0.02 μM). The selectivity studies have shown that the selectivity of prepared paraoxon imprinted sensor has found as being very high in the presence of parathion which is similar in structure with paraoxon. The paraoxon imprinted sensor has been repeatedly used for more than 7 months in many continuous experiments.     

Development of piroxicam sensor based on molecular imprinted polymer-modified carbon paste electrode

A new voltammetric sensor for piroxicam measurement is introduced. A piroxicam-selective molecularly imprinted polymer (MIP) and a non-imprinted polymer (NIP) were synthesized in a non-covalent approach using methacrylic acid (MAA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linking monomer via a free radical polymerization and then was used for carbon paste (CP) electrode preparation. The MIP, embedded in the carbon paste electrode, functioned as a selective recognition element and pre-concentrator agent for piroxicam determination. The prepared electrode was used for piroxicam measurement via a three-step procedure including analyte extraction in the electrode, electrode washing and electrochemical measurement of piroxicam. The MIP–CP electrode showed good recognition ability in comparison to NIP–CP. Some parameters affecting sensor response were optimized. Under optimum conditions the oxidation peak current was proportional to piroxicam concentration over the range 2–190 and 190–2500 nM. The detection limit was found to be 0.5 nM. This sensor has been successfully applied for the determination of piroxicam in pharmaceutical formulations and serum samples.     

An optical fiber chemical sensor for mercury ions based on a porphyrin dimer

The synthesis of a novel fluoroionophore, 5-p-[[4-(10',15',20'-triphenyl-5'-porphinato) phenyloxyl]-1-butyloxyl]phenyl-10,15,20-triphenylporphine (DTPP), and its application for preparation of a Hg(II)-sensitive optical fiber chemical sensor are described. The response of the sensor is based on the fluorescence quenching of DTPP by coordination with Hg(II). The porphyrin dimer-based sensor shows a linear response toward Hg(II) in the concentration range 5.2 x 10(-7)-3.1 x 10(-4) mol x L(-1), with a working pH range from 2.4 to 8.0. The sensor shows excellent selectivity for Hg(II) over transition metal cations including Cd(II), Co(II), Cu(II), Ni(II), Pb(II), Zn(II), and Fe(III). As a sensing agent, the porphyrin dimer shows obviously better fluorescence response characteristics toward Hg(II) compared to porphyrin monomer or metalloporphyrin. The effect of the composition of the sensor membrane was studied, and the experimental conditions were optimized. The sensor has been used for determination of Hg(II) in water samples.     

Ligand exchange based paraoxon imprınted QCM sensor

In the present work, a paraoxon imprinted QCM sensor has been developed for the determination of paraoxon based on the modification of paraoxon imprinted film onto a quartz crystal combining the advantages of high selectivity of the piezoelectric microgravimetry using MIP film technique and high sensitivity of QCM detection. The paraoxon selective memories have formed on QCM electrode surface by using a new metal–chelate interaction based on pre-organized monomer and the paraoxon recognition activity of these molecular memories was investigated. Molecular imprinted polymer (MIP) film for the detection of paraoxon was developed and the analytical performance of paraoxon imprinted sensor was studied. The molecular imprinted polymer were characterized by FTIR measurements. Paraoxon imprinted sensor was characterized with AFM and ellipsometer. The study also includes the measurement of binding interaction of paraoxon imprinted quartz crystal microbalance (QCM) sensor, selectivity experiments and analytical performance of QCM electrode. The detection limit and the affinity constant (K_affinity) were found to be 0.06 μM and 2.25 × 10⁴ M^? 1 for paraoxon [MAAP–Cu(II)–paraoxon] based thin film, respectively. Also, it has been observed that the selectivity of the prepared paraoxon imprinted sensor is high compared to a similar chemical structure which is parathion.     

按需滴定法制备掺杂型聚合物微透镜阵列

采用MMA单体与其聚合物PMMA及掺杂剂的混合溶液,以按需滴定法制备了掺杂若丹明6G的微透镜阵列。并对其焦距一致性、成像效果、表面粗糙度、透射光谱和荧光光谱等光学性能进行了测试。焦距不均匀度不超过1．8％,测定数值和理论值相差不到1．7％。表面热处理后表面粗糙度肋小于0．9nm,光学透过率从近紫外到近红外都在90％以上,可以用于光纤放大器和生物化学传感器。     

Intrinsic optical-fiber sensor for nerve agent sensing

A novel chemical-sensing technique to detect the nerve agent sarin stimulant dimethylmethylphosphonate (DMMP) is presented. This technique uses a combination of doped polypyrrole as an active chemical material coated on an optical fiber to form an intrinsic fiber-optic sensor. Sensitivity of up to 26 ppm of DMMP with response time of a few seconds is demonstrated. Influence of three different dopants, i.e., 1,5 naphthalene disulphonic acid, anthraquinone 2 sulphonic acid, and hydrochloric acid is investigated for sensor response and sensitivity. Two polymer processing techniques, i.e., in situ deposition and monomer vapor phase deposition is investigated for optimal polypyrrole morphology for DMMP sensitivity. The influence of substrate nature, i.e., hydrophilic and hydrophobic, on sensor sensitivity is studied. Organophosphate specific binding sites have been created in polypyrrole structure using Cu/sup 2+/ ions to enhance DMMP response. The selectivity issue is addressed by testing the sensor in the presence of other gases like ammonia, water vapor, and acetone which influence the electronic properties of polypyrrole.     

Monitoring of high solids content starved-semi-batch emulsion copolymerization reactions by Fourier transform Raman spectroscopy

A high solids content n-butyl acrylate/methyl methacrylate emulsion copolymerization process carried out under starved semi-batch conditions was for the first time monitored on-line by means of Fourier transform (FT)-Raman spectroscopy. Partial least squares regression was employed to build calibration models that allowed relating the spectra with solids content (overall conversion), free amounts of both n-butyl acrylate (n-BA) and methyl methacrylate (MMA), and cumulative copolymer composition. In spite of the heterogeneous nature of the polymerization, the similarities of the spectra for MMA, n-BA, and for the copolymer, and the low monomer concentrations in the reactor, the FT-Raman spectroscopy has been shown to be a suitable noninvasive sensor to accurately monitor the process. Therefore, it is well suited for on-line control of all-acrylic polymerization systems.     

用光化学旋转反应器测定酚醛树脂型感光剂的光量子产率

本文采用光化学旋转反应器,分别测定了重氮醌磺酰氯和酚醛树脂型重氮萘醌磺酸酯感光剂的光量子产率。测定了重氮萘醌磺酚氯和５０％酯化比的感光剂的光量子产率分别为０．３０４和０．２２１。对实验数据均采用线性回归方法进行处理,其相对误差和置信区间均在标准误差范围之内,实验结果表明：该类型感光剂的光分解反应符合一级反应动力学规律。５０％酯化比的感光剂不但具有较好的溶解度和稳定性,而且光量子产率仅比磺酰氯降低了２７．３％,仍具有良好的感光性。     

Ratiometric fluorescence sensor based on a pyrene derivative and quantification detection of heparin in aqueous solution and serum

A ratiometric fluorescence sensor based on pyrene was designed for selective detection of heparin in HEPES (N-(2-hydroxyethyl)piperazine-N'-ethanesulfonic acid) buffer and serum sample. Pyrene and long-chain alkanes were linked through bisquaternary functionality in the sensor which could interact with heparin via supramolecular assembly. A ratiometric fluorescent signal change of the sensor can be observed because of the specific monomer-excimer conversion of pyrene which is modulated by the supramolecular self-assembly of sensor and heparin. Upon addition of heparin, the excimer emission of the sensor at 489 nm is observed and the monomer emission intensity at 395 nm decreases concomitantly. Addition of heparin derivatives with very similar structure such as chondroitin 4-sulfate or hyaluronic acid to the same sensor solution only leads to very smaller changes in intensity ratios probably because of lower charge density and more distant spatial distribution of anions (or disadvantageous spatial orientation of anions) as compared to those of heparin. The novel sensor can effectively differentiate heparin from its derivatives with relatively low background interference and wide linear response in HEPES and serum. A linear calibration curve is obtained from 0 to 3.4 μM for heparin quantification in serum.