Development of a new gas sensor for binary mixtures based on the permselectivity of polymeric membranes: Application to carbon dioxide/methane and carbon dioxide/helium mixtures

Membrane-based gas sensors were developed and used for determining the composition on bi-component mixtures in the 0-100% range, such as oxygen/nitrogen and carbon dioxide/methane (biogas). These sensors are low cost and are aimed at a low/medium precision market.The paper describes the use of this sensor for two gas mixtures: carbon dioxide/methane and carbon dioxide/helium. The membranes used are poly(dimethylsiloxane) (PDMS) and Teflon-AF hollow fibers. The response curves for both sensors were obtained at three different temperatures. The results clearly indicate that the permeate pressure of the sensors relates to the gas mixture composition at a given temperature. The data is represented by a third order polynomial. The sensors enable quantitative carbon dioxide analysis in binary mixtures with methane or helium. The response of the sensors is fast (less than 50 s), continuous, reproducible and long-term stable over a period of 2.3×10⁷ s (9 months). The absolute sensitivity of the sensors depends on the carbon dioxide feed concentration ranging from 0.03 to 0.13 MPa.     

Separation and characterization of complex crude mixtures produced in the synthesis of therapeutic peptide hormones by liquid chromatography coupled to electrospray mass spectrometry (LC-ES-MS)

Native peptides and peptidomimetics can be synthesized in a routine way by rapid and efficient procedures. However, the final products always result in complex mixtures, in which the target peptide is contaminated with undesired side products and other impurities. Thus, it is imperative to develop analytical methods for the evaluation of the target peptide’s purity in order to obtain an effective, safe and legal pharmaceutical product. LC-ES-MS is used here in order to separate and characterize the side-products associated with several synthetic hormones with therapeutic interest: carbetocin, eledoisin, leuprolide, goserelin and triptorelin. General directions for LC-ES-MS analysis of the synthetic peptide mixtures are established. Mass information obtained offers a significant advantage for the purity assessment of therapeutic hormones and gives a key tool to enhance their process of synthesis.     

几种分子筛的转晶和混晶的控制及单一晶体的优化合成

 以六亚甲基亚胺作模板剂，在配料比一定的情况下，详细考察了反应温度和反应时间对MCM－22，ZSM－5，ZSM－35和丝光沸石分子筛成晶的影响．结果表明，MCM－22的最佳合成温度在低温区，ZSM－35易在提高反应温度或延长反应时间时形成，而作为中间相的ZSM－5和丝光沸石则在反应温度与反应时间合理匹配时才能以单一相生成．同时，探讨了晶种的加入对产物晶相的影响．在特定的温度和时间区间，能够合成出比例可控的ZSM－35＋MCM－22混晶，ZSM－5＋ZSM－35混晶和ZSM－35＋丝光沸石混晶，并从分子筛孔道和结构单元的特点出发，就转晶发生对温度和时间的依赖性作了解释．     

高效毛细管电泳－间接电导法快速分离混合糖

测定;间接电导检测法;高效毛细管电泳－间接电导法快速分离混合糖     

新型反式十氢萘类液晶的合成

反式十氢萘液晶是一种结构新颖、性能优越的TFT型显示材料.文中以1-[(2‘-正烷基)-6’-反式十氢萘基]-4-环己酮为原料,经格氏试剂与羰基的加成、脱水、还原及异构化合成系列反式十氢萘类单体液晶1～13,产率22.8％～71.0％.结构分别经过IR,^1H NMR,^13C NMR,MS鉴定.详细测试了每个化合物的DSC分析数据,据此探讨了化合物在混合液晶中的相变行为.     

Kinetic method for the simultaneous chiral analysis of different amino acids in mixtures

The kinetic method has been extended to enantiomeric excess (ee) determinations on amino acids present in mixtures. Singly charged trimeric clusters [Cu(II)(ref*)(2)(A(m)) - H](+) are readily generated by electrospraying solutions containing Cu(II), a chiral reference ligand (ref*), and the amino acids (analytes A(m), m = 1-3). A trimeric cluster ion for each amino acid is individually mass-selected and then collisionally activated to cause dissociation by competitive loss of either the reference ligand or the analyte. For each analyte in the mixture, as shown from separate experiments, the logarithm of the ratio of the fragment abundances for the complex containing one enantiomer of this analyte expressed relative to that for the fragments of the corresponding complex containing the other enantiomer is linearly related to the enantiomeric composition of the amino acid. Formation and dissociation of each trimeric complex ion are shown to occur independently of the presence of other analytes. Chiral selectivity appears to be an intrinsic property and the chiral selectivity R(chiral(m)) measured from the mixture of analytes is equal to R(chiral) measured for the pure analyte. The sensitive nature of the methodology and the linear relationship between the logarithm of the fragment ion abundance ratio and the optical purity, characteristic of the kinetic method, allow the determination of chiral impurities of less than 2% ee in individual compounds present in mixtures by simply recording the ratios of fragment ion abundances in a tandem mass spectrum.     

混甲酚甲醛炭气凝胶的制备及表征

以混甲酚和甲醛为原料,经溶胶－凝胶民、酸洗老化、超临界干燥得有机气凝胶,密度０．１５０７ｇ／ｃｍ＾３,进一步炭化得炭气凝胶。采用正交试验方法重点考察了炭化工艺条件对炭气凝胶结构和性能的影响,并用ＴＥＭ、ＴＧ、低及附等手段进行了表征。结果表明,炭化工艺条件影响因素顺序为：升温速率〉炭化终温〉维温时间,最佳炭化条件下炭气凝胶密度为０２６０ｇ／ｃｍ＾３,幽静面积人１０２２ｍ＾２／ｇ,平均戏５．６ｍｍ。Ｔ     

用Kierlik-Rosinberg的DFT方法研究活性炭分离空气中微量CCl_4

以N_2作为空气的主要成分，利用Kierlik和Rosinberg提出的密度函数理论 (density functional theory, KR-DFT)研究了N_2/CCl_4双元混合物在活性炭内的 吸附。重点讨论了孔径、压力和温度对CCl_4吸附选择性的影响，不为同条件下吸 附回收空气中的CCl_4提供了理论参考。在KR-DFT计算中。N_2分子和CCl_4分子模 型化为单点的Lennard-Jones球；流体分子与吸附剂材料之间的作用采用平均场理 论中的10-4-3模型。在KR-DFT方法中，自由能采用标度的场粒子理论(scaled field particle theory, SPT)处理。讨论了孔径、压力和温度对吸附选择性的影 响。研究结果表明，常温下当空气中CCl_4的含量为1%时，1.39nm的孔径最有利于 CCl_4的吸附。     

C7FNa-Et4NBr混合水溶液的表面吸附与胶团形成

碳氟（FC）表面活性剂（SAA）的碳原子数稍高时；在水中的溶度很小[1,2]，从而不能充分发挥其高表面活性，对实际应用不利．前文[3]报导，加入等摩尔无表面活性的有机按盐，可使全氟烷磺酸钾FC－53的溶度增大，同时表面活性提高．由此可推测，对于溶度较大，在溶液中可形成胶团     

Reduced Redlich–Kister functions and interaction studies of Dehpa + Petrofin binary mixtures at 298.15 K

In order to understand the effect of different types of interactions in liquid mixtures by applying the correlative reduced Redlich–Kister equation, excess molar volume, excess dielectric constant, deviation in refractive index, deviation in molar refraction and molar polarisation were calculated at the temperature 298.15 K and atmospheric pressure P = 101.325 kPa for the binary mixture Petrofin (1) + Dehpa (2). The experimentally determined data of density and refractive index which were published earlier were used for these calculations. The results were interpreted in terms of structural effects of the solvents.