对邻菲罗啉和银离子间的络合物及其稳定性的研究

本文采用了钠离子选择电极，在含有３０％（体积百分比）乙醇的水溶液中对邻菲罗啉和银离子间的铬合进行了研究。实验结果表明确有络合反应存在，并测定了在２５℃时在不同离子强度条件下，络合物的稳定常数。     

乙醇对肌红蛋白电化学行为的影响及其在生物传感器研制中的应用

该文首先研究了乙醇对肌红蛋白直接电化学及电催化活性的影响.结果表明,实验所用缓冲体系中乙醇的存在可以促进肌红蛋白在电极上的电子传递以及结合及催化O2的能力.紫外吸收光谱显示,乙醇体积分数不超过20%时将不会改变该蛋白质的结构.进一步研究表明,乙醇体积分数为0～20%时,肌红蛋白对H2O2的催化峰电流随实验所用缓冲体系中乙醇体积分数的增加而增大,表明少量乙醇的存在可以增强肌红蛋白对H2O2的电催化响应.在此基础上,构建了更加灵敏的H2O2生物传感器,其响应的线性范围为5.0×10-6～6.0×10-4 mol/L,灵敏度为48.7 μA/(mmol/L).     

用Origin软件进行聚乙烯醇胶凝特性研究

提出了一种用线性相关性分析聚乙烯醇溶液在Na_2B_4O_7·10H_2O的水溶液引发下的胶凝特性的方法。建立了聚乙烯醇溶液表观粘度随引发剂加入量变化关系的数学模型,给出了两种线性相关性分析方法。用Origin 6．1分析了胶凝过程的数据特点并给出了参数特征。当引发剂加入量(相对于聚乙烯醇溶液的体积分数)≤0．23%时,表观粘度对引发剂加入量呈较高的线性正相关性；随着引发剂加入量的增加,线性相关性破坏,至引发剂加入量0．929%时,表观粘度随引发剂加入量呈近指数增加。整个过程表观粘度对引发剂加入量可用模型η=-282．994 2857．966V 21939．843exp[(V-2．051)/0．113]进行拟合,相关系数r~2=0．99581。按此模型得胶凝转变点Na_2B_4O_7·10H_2O的水溶液加入量为2．051%,对应的聚乙烯醇溶液表观粘度为27518．6 mPa·s。XRD分析结果表明,该加入量引发后的聚乙烯醇完全转变为非晶态。     

基于LaFeO3/YSZ/Pt结构的混成电势乙醇传感器研究

制备了以掺钇氧化锆(YSZ)为固态电解质,LaFeO3为敏感电极的混成电势乙醇气体传感器,LaFeO3通过溶胶－凝胶法制备并用XRD分析,利用场发射电子扫描显微镜对YSZ基底和敏感电极表面形貌进行了表征, 测试结果表明制备的传感器在350℃的工作条件下对乙醇有良好的响应(400×10-6乙醇时135ｍＶ)和较快的响应时间(50×10-6乙醇时14ｓ), 测试结果还表明此传感器有良好的可重复性和选择性。     

乙酸催化加氢制乙醇反应动力学研究

我国的能源结构是"富煤、贫油、少气",以煤基乙酸为原料制备燃料乙醇是适宜我国国情的工艺路线,燃料乙醇的研究越来越受到人们的关注。本文研究了贵金属催化剂上乙酸加氢还原制乙醇的反应。在反应温度（160～240）℃、反应压力（3～7）MPa、乙酸液相体积空速（0.3～0.7）h^-1、氢气与乙酸摩尔比5～22的条件下,在等温积分反应器中研究了乙酸加氢制乙醇的反应动力学,并考察了操作条件对乙酸转化率及乙醇选择性的影响。结果表明:随温度升高乙酸转化率和乙醇选择性均明显增加,在240℃时,乙酸转化率接近平衡转化率;增加反应压力,乙酸转化率及乙醇选择性随之增加;提高乙酸液相体积空速,乙酸转化率降低,乙醇选择性呈增加趋势。根据实验数据,应用参数估值方法,得到Langmuir-Hinshelwood型动力学模型中的参数,残差分析及统计检验表明,该动力学模型是适宜的。     

Ag掺杂的SnO_2酒敏薄膜敏感特性研究

采用非醇盐溶胶—凝胶工艺在A l2O3基片上旋转涂敷制得掺Ag的SnO2薄膜。原子力显微镜和扫描电子显微镜分析显示:薄膜晶粒呈球形,600℃热处理粒径为20 nm左右。热处理温度升高,晶粒尺寸增大。气敏性能采用静态法测试,掺Ag薄膜对体积分数为50×10-6乙醇和汽油气体的灵敏度分别为32.7和4.9,与未掺Ag薄膜的14.4和7.2相比较,提高了乙醇气体灵敏度,抑制了汽油气体灵敏度,使选择性得到改善。直流加热条件下,试样电阻和电容在老化初期变化较大,数天后趋于稳定,复阻抗分析表明:长期稳定性与晶粒间界处电阻和电容值的变化有关,来源于晶界势垒高度和势垒宽度的变化,其本质可能是直流偏压作用下晶界层中的离子迁移。     

ZnSnO_3纳米粉体的制备及气敏特性

以Sn粒和Zn粒为原料,在柠檬酸体系中,用溶胶—凝胶法合成了纳米ZnSnO3粉体。用XRD,TEM对产物的组成、粒径大小、形貌进行了表征。结果表明:产物为平均粒径10 nm左右的圆球形颗粒。采用静态配气法测试了不同烧结温度下材料对还原性气体的气敏性能,发现元件对乙醇、丙酮和H2S气体均有良好的检测性能。特别是煅烧温度在600℃的纳米ZnSnO3材料在最佳工作温度为360℃时对体积分数为50×10-6的丙酮的电阻比值达69,响应—恢复特性良好,响应时间和恢复时间分别为10 s和5 s。     

络合体系中标准加入法的体积效应与校正

离子选择电极用于络合体系中的测定时,由于体系复杂,一般使用标准加入法。但是,电极在络合体系中所表现出的响应斜率往往与体系有关,给分析造成困难。本文讨论标准加入测定时的体积效应,并提出了一种新的测定方法——扣除空白电动     

溶剂法提取玉米胚黄酮的研究初报

采用溶剂法，研究了玉米胚中黄酮类化合物的提取，用正交实验法考察提取时间、乙醇浓度、提取温度及料液比等因素对黄酮产率的影响，用NaNO2-Al（NO3）3-NaOH比色法测定玉米胚中的总黄酮含量。结果表明：以80％的乙醇水溶液作为溶剂，固液比为1：12,在80℃回流2h的工艺条件较好，提取率为2．46％。     

溶胶-凝胶法制备纳米氧化镁的工艺参数研究

以六水硝酸镁Mg(NO3)2·6H2O和尿素CO(NH2)2为原料,以柠檬酸C6H7O8·H2O,无水乙醇为稳定剂,采用溶胶—凝胶法制备纳米氧化镁粉末,研究了在不同工艺条件下(柠檬酸,水,无水乙醇的用量)对溶胶—凝胶体系的稳定性的影响.并采用X-射线粉末衍射仪(XRD)和红外光谱仪对产物进行了表征。结果表明,未引入柠檬酸时,溶胶—凝胶体系的稳定性差;引入了柠檬酸后,当水:六水硝酸镁:尿素:柠檬酸:乙醇=100:9:6:9:2.1(摩尔比)时可形成稳定的凝胶体系。     

室温固相化学反应法合成CdSnO3纳米粉及其铂、钯掺杂物气敏特性研究

用室温固相化学反应法合成了CdSnO3纳米粉,以XRD、SEM、Raman光谱等检测手段对其形貌和微观结构进行了表征,并进一步以铂、钯等贵金属对其进行掺杂,研究了它们的气敏性能.实验证明室温固相法合成的CdSnO3具有粒径大小均匀、纯度高、比表面积大等特点;掺杂铂、钯等贵金属后,灵敏度和选择性都有很大提高,对汽油、液化石油气、甲烷、一氧化碳、丁烷等的抗干扰能力强,且稳定性好,可望开发为一种性能优良的酒敏传感器.     

Equilibrium swelling and kinetics of pH-responsive hydrogels: models, experiments, and simulations

The widespread application of ionic hydrogels in a number of applications like control of microfluidic flow, development of muscle-like actuators, filtration/separation and drug delivery makes it important to properly understand these materials. Understanding hydrogel properties is also important from the standpoint of their similarity to many biological tissues. Typically, gel size is sensitive to outer solution pH and salt concentration. In this paper, we develop models to predict the swelling/deswelling of hydrogels in buffered pH solutions. An equilibrium model has been developed to predict the degree of swelling of the hydrogel at a given pH and salt concentration in the solution. A kinetic model has been developed to predict the rate of swelling of the hydrogel when the solution pH is changed. Experiments are performed to characterize the mechanical properties of the hydrogel in different pH solutions. The degree of swelling as well as the rate of swelling of the hydrogel are also studied through experiments. The simulations are compared with experimental results and the models are found to predict the swelling/deswelling processes accurately.     

Solubility of CO2 in aqueous ammonia solution at low temperature

The solubility of carbon dioxide in aqueous ammonia solution with concentrations of 1.13, 2.18, 3.83, 6, and 8.11 molal was measured at atmospheric pressure and a range of temperatures from 268.15 to 288.15 K. The results showed that the solubility of carbon dioxide in ammonia aqueous solution increased with increasing temperature. The UNIQUAC-NRF model is applied to the experimental data for the present work. This modified model is used to calculate carbon dioxide solubility in aqueous ammonia solution at a range of temperatures from 268.15 to 288.15 K and atmospheric pressure. The results of AAD% (Absolute Average Deviation) show that the UNIQUAC-NRF model can accurately correlate the solubility of experimental data of carbon dioxide in aqueous ammonia solution over a wide range of low temperatures.     

Optical alcohol sensor based on dye–Chitosan polyelectrolyte multilayers

The layer-by-layer deposition technique was used to prepare polyelectrolyte multilayer (PEM) thin films that are sensitive to ethanol content in water. Cationic Chitosan was assembled with anionic acid dye, (phenyl amino)-5-[[4-(3-sulphonatophenyl) azo]-(1-naphthalenyl) azo]-1-naphthalenesulfonic acid disodium salt (Nylosan) on glass slide and characterized using UV–vis spectroscopy. The layer-by-layer deposition of Chitosan–Nylosan into PEM was studied by monitoring the increase in absorbance in the visible region (500–600 nm). The typical linear relationship between increase in absorbance and number of layers was found. The PEM thin films responded to increasing concentrations of ethanol in water with a shift of maximum absorbance (λ_max) from 540 to 580 nm. This shift was also characterized by an increase in absorbance at 600 nm which was used to monitor the response of the thin film to ethanol content in water. The characteristic color shift of the Nylosan dye occurred at a higher ethanol concentration (from 10% to 45%) in the PEM compared to its usual shift in aqueous solution (from 0% to 30%). The Chitosan–Nylosan thin films response to ethanol content was found to be linear from 10% to 45% ethanol content, which renders them useful as ethanol sensing thin films.     

Electrical response characterization of PVA–P(AA/AMPS) IPN hydrogels in aqueous Na2SO4 solution

Interpenetrating polymer networks (IPN) hydrogels composed of poly(vinyl acohol) (PVA) and poly(acrylic acid-co-2-acrylamido-2-methyl propyl sulfonic acid) (P(AA/AMPS)) were synthesized by solution polymerization. The IPN hydrogels were characterized using Fourier-transform infrared (FT-IR) and X-ray diffraction (XRD). The results indicated that strong hydrogen bond was formed between PVA and P(AA/AMPS), and the crystallinity of PVA in IPN hydrogels was declined significantly. The swelling/deswelling properties of IPN hydrogel in aqueous Na₂SO₄ solution were studied. When a sheet of water swollen IPN hydrogel (all the samples were swollen in deionized water) was placed in aqueous Na₂SO₄ solution, the IPN hydrogel shrunk. However, if a voltage was applied, the IPN hydrogel shrunk at high concentration of Na₂SO₄ solution, but swelled at low concentration. The results show that the critical concentration of Na₂SO₄ solution is about 0.005 mol/L. The stimuli response of the IPN hydrogel in electric field was also investigated. When water swollen samples were placed between a pair of electrodes in aqueous Na₂SO₄ solution, the IPN hydrogel showed significant bending behavior upon the application of an electric field. The bending direction of the IPN hydrogel depends on the concentration of Na₂SO₄ solution. At high concentration the IPN hydrogel bended toward anode, contrarily, at low concentration the IPN hydrogel bended toward cathode. The critical concentration of Na₂SO₄ solution is also about 0.005 mol/L. Further investigation showed that the gel component, concentration of aqueous Na₂SO₄ solution and the applied voltage influenced the bending speed of IPN hydrogel.     

物理交联刚果红—聚乙烯醇凝胶膜的敏感特性研究

以二甲基亚砜(DMSO)水溶液为溶剂,采用冷冻—解冻法制备高度透明的物理交联聚乙烯醇(PVA)凝胶膜,将该膜在刚果红溶液中浸泡,制备了物理交联刚果红—聚乙烯醇(PCGR—PVA)凝胶膜。利用紫外—可见光谱法测试该凝胶膜的pH敏感特性,并与化学交联的刚果红—聚乙烯醇(CCGR—PVA)凝胶膜做了对比分析。结果表明:PCGR—PVA和CCGR—PVA凝胶膜均具有良好的pH敏感性,在pH为0.29~4.33范围内对pH呈较好的线性响应,PCGR—PVA凝胶膜的灵敏度更高。PCGR—PVA凝胶膜的响应时间在弱酸中小于10 s,在强酸中小于200 s。表明PCGR—PVA凝胶是优异的pH传感材料。     

无创血糖检测中不同葡萄糖浓度的介电- 频率响应特性研究

无创血糖检测技术具有无痛感、不易感染和可连续监测等优点,是血糖检测技术发展的重要 方向。为了研究在不同频率下、不同葡萄糖浓度对介电特性的影响,该文首先以不同葡萄糖浓度的 水溶液为研究对象,探索了 500 kHz～5 MHz 频率范围内不同葡萄糖浓度水溶液的介电-频率特性。 研究表明,葡萄糖水溶液在 500 kHz～5 MHz 的响应特性与高频下的响应特性不同。在该频段下,当 葡萄糖浓度不变时,水溶液的复介电常数的实部和虚部随着频率的增大而减小;当频率不变时,水 溶液的复介电常数的实部和虚部随着葡萄糖浓度的增大而减小。其次,该文还通过对复介电常数测量 值进行二阶 Debye 模型拟合,并对 Debye 模型中的参数进行了二次多项式拟合。拟合的决定系数均 高于 0.93,最终得出了葡萄糖浓度为 0～16% 水溶液的复介电常数在不同葡萄糖浓度和频率下的相关 函数,量化了葡萄糖水溶液的复介电常数与葡萄糖浓度及频率的关系。最后,通过建立包含皮肤、血 液、肌肉的无创血糖检测模型,并采用基于时域有限差分法对模型进行仿真分析。结果表明,接收电 极 2 与 3 之间的电压差值随着葡萄糖浓度的增加而线性增大,为基于 500 kHz～5 MHz 频率范围内的 无创血糖检测提供了一定的理论基础。     

Evaluation study of different glass electrodes by an interlaboratory comparison for determining the pH of fuel ethanol

This work evaluated different combined glass electrodes by means of an interlaboratory comparison in order to determine the pH of fuel ethanol. Four electrodes with different reference electrode systems (Ag/AgCl or Pt/redox pair), liquid junctions (single or double) and internal filling solutions (aqueous KCl or ethanolic LiCl) were used in comparison with the Orion Ross Sure-flow^® N° 8172 BN electrode, a specific electrode advised by the ASTM D6423 standard. Three fuel ethanol samples with different water contents (0.1, 0.6 and 6.8%, w/w) were analyzed by nine laboratories. The results showed that all the electrodes with aqueous KCl filling solution and single liquid junction, including the Orion^® electrode, presented equivalent results. The sole electrode with ethanolic LiCl filling solution showed pH results lower than the other electrodes, whereas the sole electrode with double liquid junction, showed pH results slightly higher than those with similar filling solution containing single liquid junction. On the other hand, only the latter two electrodes presented acceptable repeatability limit values. The results indicate a need to revise the ASTM D6423 standard with the purpose of enlarging the number of electrodes that can be used to measure the pH of ethanol fuel, as well as support the harmonization of the different regional standards used to measure the pH of fuel ethanol.     

3-卤代吲唑水助质子转移反应机理的理论研究(英文)

在密度泛函B3LYP/6-311G**理论水平上,对气相和水相中3-卤代吲唑瓦变异构体进行几何构型伞自由度优化,获得它们在气相和水相中的几何结构和电子结构,PCM反应场溶剂模型用于水相计算.结果显示在气相和水相中,3.卤代吲唑的N1-H形式比N2-H形式稳定.探讨了不同的3-取代基团和溶剂化效应对互变异构体的几何结构,能量,电荷分布以及互变异构反应活化能的影响等.进一步研究了3-卤代吲唑水催化质子迁移的反应机理,提出了平面五元环的过渡态结构.     

Electrophoretic motion of two spherical particles in a rectangular microchannel

The electrophoretic motion of two spherical particles in an aqueous electrolyte solution in a small rectangular microchannel was studied in this paper. A theoretical model was developed to describe the electric field, the flow field, and the particle motion. A direct numerical simulation method using the finite element method is employed to solve the model. The simulation results clearly show how the presence of one particle influences the electric field, the flow field, and the motion of the adjacent particle. Such an influence weakens with the separation distance. In addition to the zeta potentials, the particles motion depends on their sizes: the smaller particle moves slightly faster. For a faster particle moving from behind of a slower particle, the simulation results show that the faster particle will climb and then pass the slower particle when the two particles centers are not located on the same line parallel to the applied electric field.