Chemiluminescence flow system for the determination of ammonium ion

A novel chemiluminescence (CL) system for ammonium ion combined with flow-injection analysis is presented in this paper. It is based on the CL reaction between luminol, immobilized electrostatically on an anion-exchange column, and chlorine electrochemically generated on-line via a platinum electrode from hydrochloric acid in a coulometric cell. Ammonium ion reacts with chlorine and decreases the observed CL intensity. The system responds linearly to ammonium ion concentration in the range 1.0-100 muM, and the detection limit is 0.4 muM. A complete analysis, including sampling and washing, could be performed in 1 min with a relative standard deviation of <6.0%. The system is stable for over 500 determinations and has been applied successfully to the determination of ammonium ion in rainwater samples.     

In Vitro Determination of Dobesilate in Medicine and Human Urine with Chemiluminescence Detection

A unique flow injection chemiluminescence (CL) method for the determination of calcium dobesilate in pharmaceutical preparations and human urine is presented in this paper. The analytical reagents involved in the CL reaction, luminol and ferricyanide, were both immobilized on an anion-exchange column in an FI system. The CL signal produced by the reaction of luminol with ferricyanide (the reagents had been eluted from the column through sodium phosphate injection) decreased in the presence of dobesilate. The decreased CL intensity was linear to the dobesilate concentration in the range 0.2100.0ngmL^–1. At a flow rate of 2.0mLmin^–1, one analytical cycle can be completed in 1.5min, including sampling and washing, resulting in a throughput of 40 cycles per hour. The proposed method was applied successfully to the determination of dobesilate in pharmaceutical preparations and human urine without any pre-treatment. It was found that, after oral administration, the dobesilate concentration reached its maximum after three hours, and the dobesilate metabolism ratio in 24 hours was 57.1% in the bodies of volunteers.Received September 14, 2002; accepted March 11, 2003 Published online July 16, 2003     

热处理对Nylon—11结构的影响

对不同温度热处理过的Nylon－11样品，采用广角X射线衍射（WAXD），根据X射线衍射强度理论，用多重峰图解分峰方法研究了Nylon－11结构的变化，并导出了计算Nylon－11结晶度的公式．所得结果与密度法、DSC法进行了比较．同时也给出了Nylon－11的有关热力学参数，     

电池热安全性表征模型及其相关技术

本文通过对Ni-MH电池充放电微量热及原位电化学等参量监测实验结果进行分析研究,建立包括可逆和不可逆过程的电池充放电电压和热耗散的模型.根据以热力学对电池体系在充放电过程的分析和目前国内不少学者从电池电极过程,充放电进程中电压和热耗散所受影响大小及其与时间的关系,获得了相关数理模型方程:E=Ef Ei,其中Ef=Eθ RT/F1n([M(H)]0 I/Ft)为理想电位,Ei=ktf为非理想电位,以及包括非电化学耗散Wch=g m×exp(k2t)的数理方程如下:     

K对Mn—Co—O的结构及氧化活性的影响

利用XRD,TPD,TFD-MS及催化氧化反应等实验技术,研究了K对Mn-Co-O的结构及氧化活性的影响。XRD结果表明,Mn-Co-O系已形成反尖晶石型的MnCo_2O_4结构;K-Mn-Co-O系中除MnCo_2O_4型结构外,还有新相KMnO_2存在。根据O_2的TPD-MS及吡啶的TPD结果,Mn-Co-O中添加适量的K能提高供氧活性和增加供氧数目,但酸中心数目减少,强度降低。K对Mn-Co—O催化剂氧化活性的影响随反应物分子结构的不同而异,对乙酸乙脂、苯甲酰氯等极性有机物的完全氧化反应,K能提高氧化活性,但对苯、正己烷等非极性有机物的完全氧化反应,K使其活性降低。     

Large-scale separation of metallic and semiconducting single-walled carbon nanotubes

In the applications of single-walled carbon nanotubes (SWNTs), it is extremely important to separate semiconducting and metallic SWNTs. Although several methods have been reported for the separation, only low yields have been achieved at great expense. We show a separation method involving a dispersion-centrifugation process in a tetrahydrofuran solution of amine, which makes metallic SWNTs highly concentrated to 87% in a simple way.     

Solution-phase preparation of a 560-compound library of individual pure mappicine analogues by fluorous mixture synthesis

Solution-phase mixture synthesis has efficiency advantages and favorable reaction kinetics. Applications of this technique, however, have been discouraged by the difficulty in obtaining individual, pure final products by using conventional separation and identification processes. Introduced here is a new strategy for mixture synthesis that addresses the separation and identification problems. Members of a series of organic substrates are paired with a series of fluorous tags of different chain lengths. The tagged starting materials are then mixed and taken through a multistep reaction process. Fluorous chromatography is used to demix the tagged product mixtures on the basis of the fluorine content of the tags to provide the individual pure components of the mixture, which are detagged to release the final products. The utility of fluorous mixture synthesis is demonstrated by the preparation of a 560-membered library of analogues of the natural product mappicine. A seven-component mixture is carried through a four-step mixture synthesis (two one-pot and two parallel steps) to incorporate two additional points of diversity onto the tetracyclic core. Methods for analysis and purification of the intermediates are established for the quality control of the mixture synthesis.     

尼龙—6／丙烯酸接枝膜的结构与性能

应用ＩＲ确定了尼龙－６与丙烯酸接枝反应的接枝点位于尼龙大分子酰胺键的Ｎ原子上，用Ｘ射线衍射研究了接枝膜的结晶状况，探讨了接枝率对接枝膜的电阻、离子交换容量、强度等性能的影响．     

Optimization of performance and minimization of silicate interference in continuous flow phosphate analysis

Specific reaction conditions for automated continuous flow analysis of phosphate are optimized in regard to minimizing coating and silicate interference, while maintaining high sensitivity. Use of Sb in the reagent increases sensitivity and yields absorbances with little temperature dependence. Coating can be minimized by using a final solution at a pH>0.5. At final pH of 0.78 there is maximum interference from silicate in the sample. We recommend therefore as an optimal reaction condition with minimal silicate interference, the use of Sb, a final solution pH of 1.00, room temperature for the reaction and a [H(+)]/[Mo] ratio of 70. An equation is provided to correct silicate interference in high precision phosphate determination.     

用WAXD和SAXS研究辐照聚酰胺1010结构

用ＷＡＸＤ和ＳＡＸＳ方法研究了聚酰胺１０１０的聚集态结构和结晶结构的辐射损伤过程和机理。辐射交联与裂解主要在非晶区和结晶表面或中间相发生；辐射损伤并从这里开始，随辐射剂量增大，非晶化逐渐向晶区伸展，有氢键的（０１０）晶面损伤几率高于（１００）晶面；辐射后效应导致新的交联与裂解生成，主要影响（０１０）晶面的形成与完善，使Ｌ１００及Ｗｃ变小。