Multichromic benzimidazole‐containing polymers: Comparison of donor and acceptor unit effects

This study reports a comparative study on electrochromic properties of two donor–acceptor–donor (DAD)‐type polymers namely poly(2‐heptyl‐4,7‐di(thiophen‐2‐yl)‐1H‐benzo [d]imidazole) (BImTh) and poly(4,7‐bis(2,3‐dihydrothieno[3,4‐b] [1,4]dioxin‐5‐yl)‐2‐heptyl‐1H‐benzo[d]imidazole) (BImEd). DAD‐type monomers were polymerized electrochemically on indium tin oxide‐coated glass slides to determine the optical properties of the polymers. Electrochemical p‐doping experiments were performed to determine the band gap and absorption band values of the polymer films at different redox states. Polymerization of BImTh and BImEd yields multichromic polymers. Donor and acceptor effects are studied by comparing the PBImEd and PBImTh with corresponding benzotriazole derivatives. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Electrochemical polymerization of (2-dodecyl-4, 7-di (thiophen-2-yl)-2H-benzo[d][1,2,3] triazole): a novel matrix for biomolecule immobilization

A recently synthesized conducting polymer [poly(2-dodecyl-4,7-di(thiophen-2-yl)-2H-benzo[d][1,2,3]triazole (PTBT)] was tested as a platform for biomolecule immobilization. After electrochemical polymerization of the monomer (TBT) on graphite electrodes, immobilization of glucose oxidase (GOx,β-D-glucose: oxygen-1-oxidoreductase, EC 1.1.3.4) was carried out. To improve the interactions between the enzyme and hydrophobic alkyl chain on the polymeric structure, GOx and isoleucine (Ile) amino acid were mixed in sodium phosphate buffer (pH 7.0) with a high ionic strength (250 × 10(-3) M). The solution is then casted on the polymer film, and the amino groups in the protein structure were crosslinked using glutaraldehyde (GA) as the bifunctional agent. Finally, the surface was covered with a perm-selective membrane. Consequently, cross-linked enzyme crystal (CLEC) like assembles with regular shapes were observed after immobilization. Microscopic techniques such as scanning electron microscopy (SEM) and fluorescence microscopy were used to monitor the surface morphologies of both the polymer and the bioactive layer. Electrochemical responses of the enzyme electrodes were measured by monitoring O(2) consumption in the presence of glucose at -0.7 V. The optimized biosensor showed a very good linearity between 0.05 and 2.5 × 10(-3) M with a 52 s response time and a detection limit (LOD) of 0.029 × 10(-3) M to glucose. Also, kinetic parameters, operational and storage stabilities were determined. K(m) and I(max) values were found as 4.6 × 10(-3) M and 2.49 μA, respectively. It was also shown that no activity was lost during operational and storage conditions. Finally, proposed system was applied for glucose biomonitoring during fermentation in yeast culture where HPLC was used as the reference method to verify the data obtained by the proposed biosensor.     

A Novel DNA Probe Based on Molecularly Imprinted Polymer Modified Electrode for the Electrochemical Monitoring of DNA

A DNA probe that was based on methylene blue (MB) imprinted polyvinyl pyridine polymer (MIP) modified carbon paste electrodes were developed for the first time for electrochemical monitoring of DNA. Probes were built up by adsorbing MB onto modified electrodes prior to DNA immobilization. It was shown that DNA strongly immobilizes on MIP modified electrodes when MB was adsorbed in advance of DNA immobilization. The performance of the MB imprinted polymer modified carbon paste electrodes (MIP‐CPE) to rebind the template molecule (MB) were compared to those of control polymer modified (non‐imprinted polymer NIP‐CPE) and bare (CPE) electrodes. Electrochemical signal resulting from the oxidation of guanine moiety of the immobilized probe DNA was high enough on the constructed platform, implicating that probes of this kind could be favorably used for DNA analysis. These probes exhibited high selectivity for its complementary DNA sequences (target). HBV‐DNA hybridization was studied to evaluate the selectivity of the probes for complementary, non‐complementary and mismatch sequences. The detection limit of the probe for the target DNA was 8.72 µg/mL (1.38 µM), which was better than those attained by some earlier DNA sensor studies.     

Graybody radiation phenomena in a fractional manner

In this paper, the graybody radiation phenomena has been handled with the help of fractional calculus. Fractional definition of graybody spectrum has been written in terms of Mittag‐Leffler function. The obtained data from fractional calculus approximation for nearly 2.87 × 10⁷ K have been compared with literature values and standard blackbody radiation.     

Physiological Importance of Molybdate Transporter Family 1 in Feeding the Molybdenum Cofactor Biosynthesis Pathway in Arabidopsis thaliana

Molybdate uptake and molybdenum cofactor (Moco) biosynthesis were investigated in detail in the last few decades. The present study critically reviews our present knowledge about eukaryotic molybdate transporters (MOT) and focuses on the model plant Arabidopsis thaliana, complementing it with new experiments, filling missing gaps, and clarifying contradictory results in the literature. Two molybdate transporters, MOT1.1 and MOT1.2, are known in Arabidopsis, but their importance for sufficient molybdate supply to Moco biosynthesis remains unclear. For a better understanding of their physiological functions in molybdate homeostasis, we studied the impact of mot1.1 and mot1.2 knock-out mutants, including a double knock-out on molybdate uptake and Moco-dependent enzyme activity, MOT localisation, and protein–protein interactions. The outcome illustrates different physiological roles for Moco biosynthesis: MOT1.1 is plasma membrane located and its function lies in the efficient absorption of molybdate from soil and its distribution throughout the plant. However, MOT1.1 is not involved in leaf cell imports of molybdate and has no interaction with proteins of the Moco biosynthesis complex. In contrast, the tonoplast-localised transporter MOT1.2 exports molybdate stored in the vacuole and makes it available for re-localisation during senescence. It also supplies the Moco biosynthesis complex with molybdate by direct interaction with molybdenum insertase Cnx1 for controlled and safe sequestering.     

The effects of emulsifier type,phase ratio,and homogenization methods on stability of the double emulsion

The double emulsion technology has a potential effect on the development of diversity and quality of functional foods by means of decreasing oil or salt concentration, encapsulating and controlling release of valuable components. In this study, it was aimed to formulate stable double emulsions to be used in food systems. W1/O ratios of primary emulsions, stabilized by polyglycerol polyricinoleate (PGPR), were designed as 2:8 and 4:6, and (W1/O)/W2 ratios of the double emulsions were used as 2:8 and 4:6. W/O/W phase ratios, homogenization methods applied to primary emulsion (high-speed homogenization, ultrasonic homogenization), and emulsifier types used in W2 phase [sodium caseinate (SC), xanthan gum, lecithin-whey protein concentrate] were used as independent variables. Particle size and distributions, stability, encapsulation efficiency (EE), rheological properties, long-term stability, and morphological properties of the double emulsions were investigated.

The double emulsions prepared with SC and (W1/O)/W2 ratio of 4:6, were found to have the higher stability values, higher apparent viscosity, and lower particle size. High-speed homogenization applied to primary emulsion reduced particle size of the double emulsion and increased apparent viscosity, but did not affect stability and EE of the double emulsions, significantly.     

New inequalities of Hermite-Hadamard type via s-convex functions in the second sense with applications

In this paper, we establish some new inequalities of Hermite-Hadamard type whose derivatives in absolute value are s-convex in the second sense. Finally some applications to special means of positive real numbers are given.     

Aggregation-based cutting-planes for packing and covering integer programs

Mathematical Programming - In this paper, we study the strength of Chvátal–Gomory (CG) cuts and more generally aggregation cuts for packing and covering integer programs (IPs)....