Fiber-Optic Chemical Sensor for Detection of NO2 Using Poly (3-Octylthiophene)

A fiber-optic chemical sensor (FOCS) for detection of nitrogen dioxide (NO₂) molecules is reported. The FOCS presents an optropode structure because of the transmission properties of the sensitive material. The NO₂ FOCS is activated by using the semiconductor polymer: regioregular head-to-tail poly(3-octylthiophene-2,5-diyl). The operation wavelength of the sensor is 543.5 nm such that a simple LED and detector can be used for the design of this device. The sensor response decreases after each exposure, demonstrating the reduction in sensitivity as well as irreversibility lower than 5%. However, its properties such as rapid response, high selectivity, high sensitivity (0.43 ± 0.01 muW/ppm), hygroscopic properties, and its operation at room temperature make this kind of FOCS a good alternative for NO₂ toxic gas detection.     

One dimensional main-chain crystallization kinetics of poly(3-octylthiophenes) investigated by infrared spectroscopy

Time-resolved infrared spectroscopy has been used to study the melt crystallization behavior of poly(3-octylthiophenes) (P3OT), which is a typical conductive polymer among the family of poly(3-alkylthiophenes) (P3ATs). It is found that, during the isothermal crystallization process at high temperature, the alkyl side chains of P3OT always keep in disordered state, whereas the ordering packing of conjugated backbone takes place. In order to reveal the structural changes and the crystallization kinetics corresponding to the main-chain ordering process, two spectral regions that associated with π–π stacking and the effective conjugation length of P3OT have been analyzed in detail. The characteristic IR bands of crystalline and amorphous phase are identified in each spectral region. Moreover, a simple spectral method has been proposed to calculate the evolution of crystallinity during the isothermal crystallization process of P3OT. Of particular note, the distinct one-dimensional growth kinetic of P3OT crystal has been revealed by Avrami analysis.     

AOT/异辛烷/水微乳液中结晶紫与AOT相互作用的热力学研究

用紫外-可见分光光度法在不同温度下测定了结晶紫(CV)在双-2-乙基己基硫代琥珀酸钠(气溶胶OT或AOT)为表面活性剂的W/O微乳液中的吸光度. 根据结晶紫和AOT在微乳液水滴界面缔合的模型对实验数据进行处理, 结果表明, 随着微乳液中水与AOT的摩尔比w的减小和温度的升高, 结晶紫缔合度增大, 根据不同温度下的缔合平衡常数计算了反应的热力学函数, Δ_rG_m, Δ_rH_m和Δ_rS_m     

Specific Interaction of Coproporphyrin I with Antibodies in Water and Reverse Micelles: Dimerization of Antibodies Affects Antigen Binding Site

The antigen-antibody interaction between coproporphyrin I and anti-coproporphyrin antibodies was studied by a fluorescence method in water and a reverse micellar system: n-octane/Aerosol OT. Coproporphyrin fluorescence was quenched, and coproporphyrin emission maximum was shifted to the long-wavelength region after binding to the antibodies or Fab-fragments. The mechanism of this quenching is static, most probably, by a tryptophan residue (or maybe lysine or methionine). Apparent dynamic quenching, in this case, arises from protein backbone motion. A special kind of antibody Fab-Fab dimerization was proposed.     

Optimal media planning for multi-products in segmented market

Promotion is an essential stage of any product life cycle. All firms either concerned with single or multiple products promote their products. Advertising is the most dominated form of promotion for most of the products. Our research focuses on firms which produces a multiple range of products and advertise them using available media options. The budget constraint forms the major restriction. The existing research in media allocation of multiple products ignores the market segmentation and formulates the media plan assuming all segments alike. In this paper we formulate a media planning problem for allocating the available budget in multiple media that are found suitable for the advertising of multiple products considering marketing segmentation aspect of advertising. The objective is to maximize the total reach in all the segments. Goal programming technique is used to solve the problem. A case study is presented to show the real life application of the model.     

Density-and-temperature-dependent volume translation for the SRK EOS: 1. Pure fluids

A mathematical framework for applying a density-and-temperature-dependent volume translation in a thermodynamically consistent manner was developed. Volumetric equations of state (EOS)s that incorporate this translation procedure can be used to generate derived properties, such as fugacity and enthalpy departure, that are based on isothermal departure or residuals from ideal gas state conditions. This kind of translation serves to improve the original EOS and not simply act as a correlation for molar volumes. A density-and-temperature-modified translation of this type was applied to the Soave–Redlich–Kwong EOS and was shown to possess accuracy for saturation pressure predictions equivalent to the untranslated EOS, as well as greatly improved density predictions compared to what is available when using only constant valued translation. The EOS translated in this manner retains many of the important features of the untranslated EOS, such as explicit calculation of volume roots, while having the representation capabilities of substantially more complicated models, such as the extended virial equation of Benedict, Webb, Rubin, and Starling.     

A well-defined block copolymer serving as surfactants in separation of 1,4-dihydropyridines by open-tubular capillary eletrochromatography

A novel series of diblock copolymers, poly(butyl methacrylate)(n) -block-poly(glycidyl methacrylate)(m) [P(BMA)(n) -b-P(GMA)(m) ], were synthesized by atom transfer radical polymerization and developed as covalent coating of capillaries. The excellent performance of this coating in separation of three 1,4-dihydropyridines (DHPs) derivatives (amlodipine, nicardipine, nitrendipine) was achieved when the diblock copolymers self-assembled into micelles, which was confirmed by transmission electron microscopy, dynamic light scattering, and atom force microscopy. Meanwhile, the effects of block ratio n/m, pH value, buffer concentration, and organic solvents on the separation of 1,4-DHPs were investigated in detail. Then, the relationship between the morphologies of copolymers and the separation resolutions of 1,4-DHPs was discussed. Furthermore, the proposed method exhibited good run-to-run and column-to-column precision with relative standard deviations of electroosmotic flow less than 3.0%. It was also validated with linearity of three 1,4-DHPs in the range of 0.01-1.80 mM (r(2) ≥ 99.7%), efficient recovery (94-103%), and good repeatability (≤ 3.8%). In addition, three 1,4-DHPs were successfully separated in the spiked human serum sample, which indicated the potential utility of this method in biological sample analysis.     

A quenching fluoroimmunoassay for analysis of the pesticide propazine in an apolar organic solvent, reverse micelles of AOT inn-octane: Effect of the micellar matrix and labeled antigen structure

A simple way of directly observing antigen-antibody binding in a reverse micellar system,n-octane containing reverse micelles of aerosol OT (AOT), using the hydrophobic pesticide propazine as antigen, is described. We observed two processes during fluorescein-labeled propazine (FP)-antibody (Ab) interaction in reverse micelles: (1) quenching of the fluorescence of FP after mixing of Ab and FP (due immune complex formation) and (2) restoration of FP fluorescence after addition of excess propazine to the immune complex formed. We found that the quenching efficiency depends on both the properties of the reverse micellar system (surfactant concentration, hydration degreeW ₀ = [water]/[surfactant]) and the structure of the labeled antigen. A quenching fluoroimmunoassay of propazine both in apolar organic solvents and in water is developed. The method is homogeneous. The quenching time is 10–30 min, and the detection limit of propazine is 100 nM (20 Μg/L) in organic solvent and 10nM (2 Μg/L) in water. Propazine can be added to the reverse micellar system when dissolved in AOT/octane, or in an octane/chloroform mixture, or in chloroform. This makes possible the use of the analysis directly for pesticide extracts in nonpolar organic solvents.     

Activity and Conformation of Yeast Alcohol Dehydrogenase (YADH) Entrapped in Reverse Micelles

Yeast alcohol dehydrogenase (YADH) solubilized in reverse micelles of aerosol OT (i.e., AOT or sodium bis (2-ethyl hexyl) sulfosuccinate) in isooctane has been shown to be catalytically more active than that in aqueous buffer under optimum conditions of pH, temperature, and water content in reverse micelles. Studies of the secondary structure conformational changes of the enzyme in reverse micelles have been made from circular dichroism spectroscopy. It has been seen that the conformation of YADH in reverse micelles is extremely sensitive to pH, temperature, and water content. A comparison has been made between the catalytic activity of the enzyme and the α-helix content in the conformation and it has been observed that the enzyme is most active at the maximum α-helix content. While the β-sheet content in the conformation of the entrapped enzyme was found to be dependent on the enzyme–micelle interface interaction, the α-helix and random coil conformations are governed by the degree of entrapment and the extent of rigidity provided by the micelle core to the enzyme structure.     

Effect of Solvent Annealing Temperature on Crystal Modifications and Phase Transition Behavior of Regioregular Poly（3-octylthiophene）

In present study, the effect of the solvent annealing temperature on the crystal modifications and the phase transition behavior of the subsequently dried poly（3-octylthiophene） （P3OT） film has been investigated by the combination of DSC, WAXD and FTIR techniques. When chloroform is employed as the solvent, it is unexpectedly found that form I and form II crystal modifications of P3OT could be respectively obtained by room temperature and low temperature annealing. Comparing to the mostly used solvent reported for preparing form II, i.e. carbon disulfide （CS2） which is toxic and corrosive, chloroform is less toxic and corrosive and more suitable for solution processing of P3OT. Therefore, this finding provides an alternative way to obtain form II. By temperature dependent IR spectroscopy, the structural evolution of P3OT during the form II to form I phase transition process has also been studied in detail.