Approach on quantitative structure-activity relationship for design of a pH neutral carrier containing tertiary amino group

The quantitative structure-activity relationship (QSAR) for neutral carriers used to prepare hydrogen ion sensors has been studied. A series of synthesized carrier compounds were taken as the training set. Five molecular structure parameters of the compounds were calculated by using CNDO/2 algorithm and used as feature variables in constructing QSAR model. The lower and upper limits of the linear pH response range were taken as the activity measure. The corresponding model equations were derived from the stepwise regression procedure. With the established QSAR model, a new pH carrier, (4-hydroxybenzyl) didodecylamine (XIII) was proposed and synthesized. The PVC membrane pH electrode based on carrier XIII with a wide pH linear response range of 2.0-12.5 was prepared. Having a theoretical Nernstian response slope of 57.2 ± 0.3 mV/pH (n = 5 at 25 °C) without a super-Nernstian phenomenon, the sensor had low resistance, short response time, high selectivity and good reproducibility. Moreover, the sensor was successfully applied to detecting the pH value of serum samples.     

Nonionic surfactant-selective electrode and its application for determination in real solutions

A liquid membrane nonionic surfactant sensitive electrode has been prepared, based on a new barium pseudocationic complex of a highly ethoxylated fatty alcohol polyglycol ether and tetraphenylborate as sensing material. The complex has been incorporated into the plasticized PVC-membrane and used as sensing material.The electrode exhibited positive linear non-Nernstian response toward different nonionic surfactants and sub-Nernstian response toward tetraphenylborate with the lower detection limit of 3.3 × 10⁻⁷ mol dm⁻³ in barium chloride solution.The interfering effect of some alkaline, alkaline earth, and heavy metal cations, has been demonstrated by displaying their calibration curves compared with that of Triton X-100.The electrode has been used as an end-point indicator for potentiometric titration of analytical and technical grade polyethoxylated nonionic surfactants, modelled detergent products, and commercial detergents.     

PVC membrane electrode based on triheptyl dodecyl ammonium iodide for the selective determination of molybdate(VI)

Novel polyvinyl chloride (PVC) membrane electrodes based on triheptyl dodecyl ammonium iodide have been developed. In the presence of 12.5 mM H₂O₂, these electrodes are capable of determining molybdate(VI) ion. The electrodes exhibit near-Nernstian responses over a wide concentration range (2.0 × 10⁻⁶ to 5.0 × 10⁻³ M). The proposed electrodes demonstrate satisfying selectivity for molybdate(VI) ion in the presence of a wide variety of anions other than iodide, and can be used in the pH range 5.0-7.0. Moreover, the electrodes show an average response time of 2-3 min and can be used over a period of 2 months without any significant deviation being observed. In the light of our results, the response mechanism of the electrode is discussed and HMoO₂(O₂)₂⁻ is suggested as the response ion. The proposed electrode has been used to measure molybdenum in ore samples, and the results were in agreement with those obtained by means of ICP analysis.     

Catalytic behavior of tris(2,2'-bipyridine)iron(II) complex in chemiluminescence reaction of luminol in reversed micellar medium of cetyltrimethylammonium chloride

Tris(2,2'-bipyridine) complex of iron(II) was found to cause an increase in the chemiluminescence (CL) emission of luminol dispersed in the reversed micellar medium of cetyltrimethylammonium chloride (CTAC) in 1:1 (v/v) dichloromethane-cyclohexane/water, when the iron(II) complex in dichloromethane was mixed directly with the reversed micellar solution containing luminol. Visible absorption measurements showed that, when dispersed in the CTAC reversed micellar medium, the iron(II) complex dissociates easily. In the reverse micelle, subsequently the free iron(II) ion produced may catalyze the CL oxidation of luminol even in the absence of hydrogen peroxide. The CL emission produced under the optimized experimental conditions was detectable at a minimum iron(II) concentration of 1.0 x 10(-9) M using a flow injection system.     

Novel use of mesoporous aluminas as supports for Cp2ZrCl2 and Cp*ZrMe3: Ethylene polymerization and formation of polyethylene nanofibers

Mesoporous aluminas with average pore sizes of 4.3–7.8 nm were prepared by anodization of an aluminum film (AAO), and by a sol–gel templating method (TPL). In addition to a commercial alumina and sulfated TPL, the aluminas were used as supports for cyclopentadienyl zirconocene dichloride (Cp₂ZrCl₂) and trimethyl(η5‐pentamethylcyclopentadienyl)zirconium (Cp*ZrMe₃) and tested in the polymerization of ethylene. The metallocenes supported on the alumina prepared with the templating method and its sulfated modification exhibited polymerization activities of 440 and 350 kg_PE/(mol_Zr × h × bar), respectively, comparable to that obtained with silica‐supported metallocenes (390 kg_PE/(mol_Zr × h × bar)). The acid site distribution of the aluminas was studied with FTIR and temperature programmed desorption (TPD) of pyridine, and also the amount of medium and strong acid sites was determined gravimetrically from the adsorption of pyridine. Relative to the surface area, AAO with the highest amount of acid sites (2.10 μmol_py/m) adsorbed Cp₂ZrCl₂ and Cp*ZrMe₃ the most. Study of the polymers' morphology with a scanning electron microscope revealed polyethylene nanofibers in all the polymer samples, also in those obtained from the reference polymerizations with homogeneous Cp₂ZrCl₂ and Cp*ZrMe₃. This finding suggests that a catalyst support with a tubular pore structure is not a prerequisite for the formation of polymer nanofibers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4002–4012, 2007     

熊猫光纤的结构与双折射特性关系研究

本文用微元算法研究了熊猫光纤的结构参量对熊猫光纤双折射特性(拍长)的影响.由实验数据拟合出了计算拍长的熊猫光纤掺杂区的有效热膨胀系数.计算结果表明,熊猫光纤的猫眼半径、猫眼与纤芯的距离、猫眼的不一致等都是影响拍长的因素.所得结果对熊猫光纤的制作提供了理论指导.     

Biodegradable Composites of Poly(lactic acid) with Cellulose Fibers Polymerized by Aluminum Triflate

Biodegradable polymer composites consisting of poly(lactic acid) (PLA) and cellulose fibers (CF) were prepared by our newly developed method. L-Lactic acid (LA) was reacted by ring-opening polymerization with aluminum triflate as a catalyst, glycerol as an initiator and CF as a filler, in simple plastic tubes at 100 °C for 6 hours. By this method, CF could be mixed with the polymer matrix easily and homogeneously. The molecular weight and molecular weight distribution of the PLA matrix were determined by gel permeation chromatography (GPC). The M_n of the composite samples decreased from 6200 to 2800 with increasing CF content. The molecular weight distribution of composites was around 2.5 regardless of the CF content. Biodegradation of samples was determined by measuring the results from the Microbial Oxidative Degradation Analyzer (MODA) and the weight loss in compost. Biodegradation of composite samples of PLA with CF increases with increasing CF content as measured by the MODA. Apparent density of composite samples was calculated by using the weight and sizes of column shape specimens. The density of the composite samples was a bit lower than that of PLA pure samples without CF. Mechanical properties such as the elastic modulus and strength were investigated by compression tests using column shape specimens. For the sample with filter paper as CF, the strength of composite samples increases with increasing CF content.     

Migration of Additives from Poly(vinyl chloride) (PVC) Tubes into Aqueous Media

The stability and migration product of medical PVC tubes plasticized with polyadipates were investigated by ageing in phosphate buffer at pH 1.679 and water at different temperatures. Changes in the PVC tubes were studied by water absorption, weight loss, Fourier infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The low molecular weight migration product that was released was extracted and silylanized before gas chromatography/mass spectroscopy (GC/MS) identification and quantification. After 70 days, the weight loss was less than 0.5% and only a small amount of adipic acid migrated when a tube was aged at 37°C in water and phosphate buffer (pH 1.679), and at 70°C in water after 56 days. However, when aged at 70 and 110°C, gradual deactivation of heat stabilizer after 21 days of ageing in buffer solution and separation of plasticizer from PVC matrix occurred. When the tube was aged at 110°C, significant degradation of both polyadipates and PVC were observed. Adipic acid and 1,4-butanediol monomers and oligomers of polyadipate were the major migration products from polyadipates in the water ageing solution, while only a relatively high amount of adipic acid was identified as the main product in the buffer ageing solution.     

对甲苯磺酰氯对聚酰胺胺树枝形聚合物的端基修饰与表征

用对甲苯磺酰氯对聚酰胺胺(PAMAM)树枝形聚合物进行了端基修饰,以第5代为例采用元素分析,IR和^1H NMR等方法对产物进行了表征,结果表明：以83％的较高产率得到了预期的产品,产品的官能化程度达到99％。新的壳层使其有不同于PAMAM的溶解性,显示出在含芳基有机溶剂感应方面的潜在应用。     

4A沸石从水溶液中吸附氯化十四烷基吡啶

4A沸石可部分或全部代替三聚磷酸钠,以减少合成洗涤剂对水质富营养化的影响,在硬水中使用也不致降低洗涤效力.本文研究了4A沸石在不同pH水溶液中和无机盐存在下对氯化十四烷基吡啶(TPC)的吸附作用,初步探讨了吸附机制.