Synthesis and spectroelectrochemistry of dithieno(3,2‐b:2′,3′‐d)pyrrole derivatives

New π‐conjugated polymers containing dithieno(3,2‐b:2′,3′‐d)pyrrole (DTP) were successfully synthesized via electropolymerization. The effect of structural differences on the electrochemical and optoelectronic properties of the 4‐[4H‐dithieno(3,2‐b:2′,3′‐d)pyrrol‐4‐yl]aniline (DTP–aryl–NH₂), 10‐[4H‐dithiyeno(3,2‐b:2′,3′‐d)pirol‐4‐il]dekan‐1‐amine (DTP–alkyl–NH₂), and 1,10‐bis[4H‐dithieno(3,2‐b:2′,3′‐d)pyrrol‐4‐yl] decane (DTP–alkyl–DTP) were investigated. The corresponding polymers were characterized by cyclic voltammetry, NMR (¹H‐NMR and ¹³C‐NMR), and ultraviolet–visible spectroscopy. Changes in the electronic nature of the functional groups led to variations in the electrochemical properties of the π‐conjugated systems. The electroactive polymer films revealed redox couples and exhibited electrochromic behavior. The replacement of the DTP–alkyl–DTP unit with DTP–aryl–NH₂ and DTP–alkyl–NH₂ resulted in a lower oxidation potential. Both the poly(10‐(4H‐Dithiyeno[3,2‐b:2′,3′‐d]pirol‐4‐il)dekan‐1‐amin) (poly(DTP–alkyl–NH₂)) and poly(1,10‐bis(4H‐dithieno[3,2‐b:2′,3′‐d]pyrrol‐4‐yl) decane) (poly(DTP–alkyl–DTP)) films showed multicolor electrochromism and also fast switching times (<1 s) in the visible and near infrared regions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40701.     

The use of basalt powder as a natural heterogeneous catalyst in the Fenton and Photo-Fenton oxidation of cationic dyes

The use of naturally present heterogeneous catalysts has recently been an essential issue in the Fenton and photo-Fenton processes. In this study, the uses of basalt as a catalyst for the Fenton and photo-Fenton reactions for methylene Blue (MB) and Basic Red 18 (BR18) degradations were investigated. Basalt was selected because of the presence of the iron (III) oxide in the structure. Basalt was characterized by X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) analysis to obtain the chemical composition and the crystalline phase. The surface charge and the surface area were obtained by zeta potential and Brunauer Emmett-Teller (BET) analysis. Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscope (SEM) were utilized to explore the functional group and the surface morphology. Fenton and photo-Fenton processes were applied to explore the best degradation method. Adsorption was also tested and the adsorption process had minimum removal efficiency (12% for MB and 17% for BR18). The removal efficiencies for MB and BR18 by the Fenton process were 87% and 28%, respectively. The photo-Fenton process had maximum removal efficiency with 100% for MB and 70% for BR18. The optimum conditions were 70 mg/L dye concentration, 5 mM H₂O₂, 1.0 g/L basalt loading and pH 2. Basalt has shown reuse capability as a catalyst for three consecutive cycles.     

Adaptive three-dimensional cellular genetic algorithm for balancing exploration and exploitation processes

This paper presents a new adaptive algorithm that aims to control the exploration/exploitation trade-off dynamically. The algorithm is designed based on three-dimensional cellular genetic algorithms (3D-cGAs). In this study, our methodology is based on the change in the global selection pressure induced by dynamic tuning of the local selection rate. The parameter tuning of the local selection method is a way to define the global selection pressure. A diversity speed measure is used to guide the algorithm. Therefore, the integration of existing techniques helps in achieving our aims. A benchmark of well-known continuous test functions and real world problems was selected to investigate the effectiveness of the algorithm proposed. In addition, we provide a comparison between the proposed algorithm and other static and dynamic algorithms in order to study the different effects on the performance of the algorithms. Overall, the results show that the proposed algorithm provides the most desirable performance in terms of efficiency, efficacy, and speed for most problems considered. The results also confirm that problems of various characteristics require different selection pressures, which are difficult to be identified.     

A Chemometric Approach to Assess the Frying Stability of Cottonseed Oil Blends During Deep-Frying Process: I. Polar and Polymeric Compound Analyses

The main goal of the present study was (i) to determine the formation of degradation products in cottonseed oil (CSO) blends during deep frying process by adsorption and high performance size exclusion chromatography techniques and (ii) to evaluate the impacts of food additives on total polar (TPC) and polymeric compound (PTAG) formation using a chemometric approach. In order to prepare the frying CSO blends; ascorbic palmitate, mixed tocopherols, dimethylpolysiloxane, lecithin and sesame oils were used as additives. To determine the real impacts of additives, a quarter-fraction factorial experimental design with two levels and five factors was used. The changes in TPC and PTAG data were carefully evaluated during 10 h of frying at 170 ± 5 °C with normal distribution (ND) graphs and analyzed using a one-way analysis of variance (ANOVA), followed by Tukey’s Post-hoc test (α = 0.05). The results indicated that the increasing values for TPC and PTAG during the frying processes for all blends, TPC and PTAG contents reached maximum levels of 16.37 and 6.01 % respectively, which are below the limit values stated by official authorities for the quality assessment of frying oils. The ANOVA test results were in good agreement with ND graphs and data indicated that the impact of mixed tocopherols was significant for TPC formation, meanwhile the impact of lecithin and ascorbic palmitate × dimethylpolysiloxane were significant for PTAG formation. Thus, the present study should be considered to be a very useful guide for developing new frying oil formulations based on CSO by using food additives.     

Ozonation of Spent Reactive Dye-Baths: Effect of HCO3?/CO32? Alkalinity

The effect of carbonate and bicarbonate alkalinity (soda ash buffer as 5,180 mg/L HCO3? alkalinity at pH 7 and as 5,100 mg/L CO32? alkalinity at pH 12) on the ozonation of reactive vinylsulphone dyestuffs in a simulated spent dye-bath has been studied at varying pHs. Adsorbable organic halogen (AOX) formation due to the high chloride content of the effluent and detoxification, which was evaluated in terms of the relative toxicity index Itox determined from the ED50 values for the marine photobacteria Vibrio fischeri, were also evaluated. Highest total organic carbon (56%), chemical oxygen demand (44%), and UV254 (77%) removals were achieved at pH 7 in the presence of HCO3? alkalinity. The fastest decolorization was observed for the case pH 2, the first order decolorization rate constant found as k620 = 0.16?min?1, closely followed by the pH 12 case with soda ash (k620 = 0.12?min?1) case. No positive correlation was evident between AOX, whose maximum value (=1.3 mg/L) appeared after 40 min ozonation at pH 7 and decreased to 0.54 mg/L after 120 min treatment, and Itox, which decreased to 0.16 at t = 50?min and increased rapidly thereafter. The Itox values were more related to color abatement kinetics. The maximum relative toxicity index of Itox = 0.83 occurred after 120 min. It was also established that the presence of alkalinity in the spent reactive dye-bath had no negative impact on the oxidation rates. In contrast, its absence seriously inhibited treatment efficiency. It is speculated that, with added soda ash, the carbonate radicals HCO3? and CO3??, which are more stable and selective than OH?, were produced and promoted the oxidation process.     

Electrorheological properties of kaolinite,polyindole, and polyindole/kaolinite composite suspensions

In this study, polyindole (PIN) and polyindole/kaolinite (PIN/KAO) composite were synthesized by free radical polymerization using FeCl₃ as an initiator. Average particle sizes (d₅₀) of PIN and PIN/KAO composite were determined by dynamic light scattering (DLS) as 7.2 and 6.2 μm, respectively. The samples were characterized by FTIR, elemental analysis, DSC/TGA and SEM measurements. Suspensions of KAO, PIN, and PIN/KAO composite were prepared in silicone oil (SO) and the sedimentation stabilities were determined. Electrorheological (ER) properties of these suspensions were studied as a function of dispersed phase concentration, shear rate, shear stress, and temperature; and yield stresses and excess shear stresses determined. Further, dielectric properties of KAO, PIN, and PIN/KAO composite were investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effects of growth rate and temperature gradient on the microstructure parameters in the directionally solidified succinonitrile–7.5 wt.% carbon tetrabromide alloy

Succinonitrile (SCN)–7.5 wt.% carbon tetrabromide (CTB) alloy was unidirectionally solidified with a constant growth rate (V = 33 μm/s) at five different temperature gradients (G = 4.1–7.6 K/mm) and with a constant temperature gradient (G = 7.6 K/mm) at five different growth rates (V = 7.2–116.7 μm/s). The primary dendrite arm spacings, secondary dendrite arm spacings, dendrite tip radius and mushy zone depths were measured. Theoretical models for the microstructure parameters have been compared with the experimental observations, and a comparison of our results with the current theoretical models and previous experimental results have also been made.     

Equalization for discrete multitone transceivers to maximize bitrate

In a discrete multitone receiver, a time-domain equalizer (TEQ) reduces the intersymbol interference (ISI) by shortening the effective duration of the channel impulse response. Current TEQ design methods such as the minimum mean-squared error (MMSE), maximum shortening SNR (MSSNR), and maximum geometric SNR (MGSNR) do not directly maximize bit rate. We develop two TEQ design methods to maximize the bit rate. First, we partition an equalized multicarrier channel into its equivalent signal, noise, and ISI paths to develop a new subchannel SNR definition. Then, we derive a nonlinear function of TEQ taps that measures the bit rate, which the proposed maximum bit rate (MBR) method optimizes. We also propose a minimum-ISI method that generalizes the MSSNR method by weighting the ISI in the frequency domain to obtain higher performance. The minimum-ISI method is amenable to real-time implementation on a fixed-point digital signal processor. Based on simulations using eight different carrier-serving-area loop channels, (1) the proposed methods yield higher bit rates than MMSE, MGSNR, and MSSNR methods; (2) the proposed methods give three-tap TEQs with higher bit rates than 17-tap MMSE, MGSNR, and MSSNR TEQs; (3) the proposed MBR method achieves the channel capacity (as computed by the matched filter bound using the proposed subchannel SNR model) with a five-tap TEQ; and (4) the proposed minimum-ISI method achieves the bit rate of the optimal MBR method     

A bis-selenophene substituted alkoxy benzene derivative as a highly stable novel electrochromic polymer

Up to date there are few studies reporting the use of selenophene derivatives as electrochromic polymers. This report highlights the synthesis of a selenophene containing multi-ring aromatic polymer which possesses reasonable optical contrasts at both visible and near-IR regions. Electrochemical synthesis of a conducting polymer from a multi-ring aromatic monomer, 2-(2,5-bis(hexyloxy)-4-(selenophen-2-yl)phenyl)selenophene (BSB(OC₆H₁₃)₂), was achieved at a lower potential than its corresponding parent, selenophene. The strong absorption band for the undoped polymer was 474 nm and the onset energy for the π–π^* transition (Eg) was 1.9 eV (645 nm).A novel dual-polymer electrochromic device was constructed in sandwich configuration where poly(BSB(OC₆H₁₃)₂) was used as the anodically coloring material. It is the first electrochromic device where a selenophene-containing polymer was used as an active layer. The device switches between a rose-colored state and a blue-colored state with a fast response time (less than 1 s).