Nafion修饰Ag/AgCl参比电极的研制及其在pH电化学传感器中的应用

制备了Nafion修饰的Ag/AgCl参比电极,参比电极电位(25℃)为-47.5±1mV,制备的电极有良好的重现性,电极电位不受溶液pH值和Cl-浓度变化的影响,有良好的抗S2-I、-离子干扰能力,且有较好的抗脉冲电流干扰能力。该参比电极适用于间歇式测试场合,可以保证稳定的参比电位;可用于基于W氧化物pH电极的电化学传感器,传感器的内阻为22kΩ,小于玻璃pH电极计内阻(1~10MΩ)。     

铅笔芯修饰聚苯胺制作微型复合pH电极的性能

在0.3mm直径的铅笔芯上电修饰聚苯胺,封入玻璃毛细管中,并与Ag/AgCl电极组合成复合微型pH电极.经实验测试,该电极的pH响应特性良好,在pH1～11的线性范围内,能斯特斜率为(-56.4±0.5)mV/pH,线性相关系数不小于0.996.作为参比的Ag/AgCl电极性能稳定.由于电极是复合微型化的,所以可用于活体微区测定.     

聚溴酚蓝修饰玻碳电极的制备及电化学性质

在含溴酚蓝的磷酸缓冲溶液中,应用循环伏安法于经预处理的玻碳电极上形成聚合物薄膜.结果表明,在-1. 0V~+1. 8V(vs.Ag/AgCl)扫描电位之间形成的薄膜具有较高的电活性和稳定性.该电极对抗坏血酸电化学氧化有催化作用,既使抗坏血酸的氧化电位负移了 270mV,又增大了其氧化峰电流.催化峰电流与抗坏血酸浓度在 2. 5~250μg/mL范围内呈良好的线性关系.     

集成化金膜阵列电极的制作研究

以聚乙烯不干胶掩膜版法结合金属溅射沉积技术在FR-4玻璃纤维版上制作了由6个金膜工作电极(1 mm×2 mm)、1个大面积金膜对电极(2 mm×13 mm)和1个厚膜Ag/AgCl参比电极构成的集成化金膜阵列电极系统,并利用电化学手段对阵列电极系统进行了考察。研究结果表明,K3Fe(CN)6在厚膜Ag/AgCl/1.0 mol/L NaCl参比电极上的式电位与商业Ag/AgCl/3.0 mol/L NaCl参比电极相差0.067 V;参比电极放置1个月后,测量电位未发生明显变化。利用扫描电化学显微镜对工作电极表面平整度进行考察,结果表明工作电极表面具有较好的平整度。通过测量H2SO4还原峰面积评价了工作电极电化学面积的批内、批间一致性;通过K3Fe(CN)6在电极上的Ipa/Ipc比值评价了工作电极电化学特性的批内、批间一致性。结果表明,阵列电极面积和电化学特性具有良好的批内和批间一致性。对集成化金膜阵列电极系统的研究结果表明,聚乙烯不干胶掩膜版法结合金属溅射沉积技术制作的阵列电极能够满足电化学电极的要求,可作为电化学生物传感器的基础电极。     

无液接裸露式Ag/AgCl参比电极的研制及应用

提出了一种无液接裸露式Ag/AgC l参比电极制备方法,测试了该参比电极的稳定性、重现性、可逆性、响应时间、温度影响等因素。实验结果表明,该电极电位稳定在49 mV,响应时间在30 s以内时,具有重现性、可逆性好,使用寿命长,温度影响小等特点,可替代饱和甘汞和Ag/AgC l参比电极。     

脉冲磁场氯离子选择电极瞬时电位分析研究

研究了脉冲磁场下AgCl电极对Cl-的响应,提出脉冲磁场离子选择电极瞬时电位分析方法。该方法可以实现快速高精度的测量。在脉冲磁场作用下AgCl电极对Cl-试液响应的瞬时峰电位Vp不受平衡电位值的影响,有很好的再现性和准确性,多次测量所得的峰电位最大偏差小于5.0 mV,平均偏差小于2.23 mV,明显优于常规电位分析方法;氯离子浓度c(Cl-)在1×10-4~0.1 mol/L范围内Vp~lgc(Cl-)有很好的线性关系,且离子的瞬时活度大于常规分析方法的活度,用“离子氛”理论解释了电位的变化。用该法测量了氯碱电解液的Cl-的浓度,与化学分析方法比较得到一致的结果。     

邻碘苯甲酸电还原脱碘的原位红外光谱研究

采用循环伏安法研究了邻碘苯甲酸在NaOH溶液中的电化学还原反应,与Pt和Ti等电极相比,Ag和Cu电极对邻碘苯甲酸具有较好的电还原活性,还原电位向正电位方向移动.通过原位红外光谱技术研究了邻碘苯甲酸在Ag和Cu电极上的电还原机理.结果表明,在电位高于-800 mV时,邻碘苯甲酸在Ag电极表面先形成吸附中间态R…I…Ag,而在Cu电极表面以负离子形式存在.随着电位的进一步负移,邻碘苯甲酸在Ag和Cu电极上均发生脱碘加氢反应,经还原得到最终产物苯甲酸.     

双层聚合膜可乐定选择性涂丝电极的研究

报告一种新型双层聚合膜可乐定涂丝电极的研制。通过电化学聚合,在铂丝表面修饰一层具有导电性能的聚苯胺薄膜,外层涂PVC膜(含四苯硼酸-可乐定活性物质)。此种电极既保持了涂丝电极的优点,又具备较好的稳定性和重现性,连续测定8h,电位值漂移0.8mV,线性范围为1×10^-1～8×10^-6mol/L,电极响应斜率56.7mV/decade;用加入稀释法测定了回收率,平均回收率为100.9%,标准偏差为1.3%。     

铁电极电还原溴化钠甲醇溶液反应动力学和机理

研究溴化钠（NaBr）甲醇溶液在铁电极上电还原反应动力学和机理对于二茂铁电化学制备、非水体系中二氧化碳（CO₂）的电还原和有机电合成等领域具有实际价值和科学意义, 但对此未见详细报道. 本文采用极化曲线和电化学阻抗谱等技术详细地研究了该体系的电还原动力学和机理. 结果表明: 反应物为甲醇而Na⁺只起导电作用; 电极电位是该体系中唯一状态变量, 其对甲醇电还原速率常数的影响符合阿仑尼乌斯唯象方程式; 电还原过程不受扩散极化控制, 溶液欧姆极化是主要极化形式; 甲醇电还原依法拉第定律计量地产生氢气, 反应活化能约为26.2 kJ·mol^-1.     

钛/活细胞界面原位EIS研究

设计了原位电解池用于生物材料/活细胞界面电化学交流阻抗谱(EIS)的测量, 原位观测了钛/MG63细胞界面EIS行为及其随时间的变化. 原位电解池中引入Ag/AgCl作为参比电极, 解决了EIS测量过程中高频部分信号失真的问题. 钛/MG63细胞界面EIS研究初步结果表明: 活细胞在钛电极表面附着, 可改变界面双电层结构和电极的表面状态, 进而影响界面的电化学性质. 实验发现, 由于钛电极表面氧化层的阻抗信号处于中低频段, 而细胞膜层自身的电化学阻抗响应位于高频范围, 由此, 可分别分析不同的电极过程, 解析其相互关系, 研究活细胞在生物材料表面的作用机理.     

Relativity Between Extrication Wave of Mental Load (EML) and Emot''''on

This experiment which was divided into three items studied the relativity between normal human emotion and extrication wave of mental load (EML) in a paradigm of combining CNV feedback with EML. Fourteen young persons were taken as subjects. After Fz, Cz, Pz, P_3—T_5 and P_4—T_6 were recorded, shorter EML latency and higher EML amplitude were caused by positive emotion in comparison with those caused by negative emotion. EML changes of the five recorded points were consistent under the effects of positive and negative emotions. This experiment also discussed the question of EML brain sources. Under the emotional conditions provided in the present experiment, EML possibly can be regarded as ERP index reflecting its positive and negative attributes.     

EFFECT OF SIMULATED WEIGHTLESSNESS ON THE RESPONSE CHARACTERISTICS OF HUMAN BRAIN

In order to systematically investigate the effects of simulated weightlessness on thefunction state of human brain, 15° head-down tilt (HDT) was used to simulate weightless-ness, and the response changes of event-related EEG power spectra, medium-frequencysynchronous potentials and slow-waves were examined in the present study. It was foundthat HDT had characteristic effects on the above EEG responses, suggesting that the ef-fects mainly occurred in the brain's regulatory system, therefore, resulting in changes ofthe brain function state.     

Identification of epilepsy from intracranial EEG signals by using different neural network models

In this work, a framework is provided for identifying intracranial electroencephalography (iEEG) seizures based on discrete wavelet transform (DWT) analysis of iEEG signals using forward propagation and feedback neural networks. The performance of 5 different data sets combination classifications is studied using the probabilistic neural network (PNN), learning vector quantization neural network (LVQ) and Elman neural network (ENN). Different feature combinations serve as the input vectors of the classifiers to obtain the best outcomes. It has been found that PNN has less running time and provides better classification accuracy (CA) than ENN and LVQ classifiers for all 5 classification problems. It is worth noticing that the CA for the C-D classification task, which shows the status of pre-ictal versus post-ictal, has been greatly improved, and reached 83.13%. Hence, the epilepsy iEEG signals pattern recognition based on DWT statistical features using the PNN classifier is more suitable for forming a reliable, automatic classification system in order to assist doctors in diagnosis.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.