A pyrolysis study on C4–C8 symmetric ethers

Pyrolysis of diethyl (C₄), di-n-propyl (C₆), di-isopropyl (C₆) and di-n-butyl (C₈) ethers were studied in a jet-stirred reactor between 720 and 1140 K, at 10 atm with an initial ether mole fraction of 0.1%. Major common pyrolysis products were observed to be CO, CH₄, H₂, and C₂H₄. All ethers produced the n/2 alcohol and olefin as products of molecular reaction to a small extent. Under pyrolysis conditions at 10 atm, hydrogen abstraction reactions by H atoms and CH₃ radicals were found to be important. Acetylene and benzene were formed for all ethers when T > 1000 K. A kinetic mechanism is used to represent these results. This study shows that there is need of systematic studies in determining site specific rate constants of important fuel related reactions of ethers.     

Synthesis of chalcone‐containing methacrylate‐based hydrogen bonded side chain liquid crystalline polymer and its dielectric properties

In this work, a new methacrylate‐based hydrogen bonded side chain liquid crystalline polymer having chalcone moieties (HBCP) was prepared from poly(4‐(3‐(pyridin‐4‐yl)acryloyl) phenyl methacrylate) and 11‐(4‐cyanobiphenyl‐4(‐oxy) undekan‐1‐ol (LC11)) by molecular self‐assembly processes via hydrogen bond formation between nitrogen of the HBCP and hydroxyl group of the LC11. The formation of H bond was confirmed by using Fourier transform infrared (FTIR) spectroscopy. The phase transition temperatures and liquid crystalline phases of the HBCP were examined by DSC and POM measurements. The dielectric properties of HBCP have been determined by impedance analyzer within the frequency interval of 100 Hz–15 MHz. According to Cole–Cole plot, the equivalent circuit of the LC system has been found as a capacitor in parallel with a resistor. The resonance frequency, f_r, of the R–C circuit has also been calculated as 1.59 MHz by phase angle versus frequency curve. The dielectric relaxation type of HBCP has been determined as nearly‐Debye type because the absorption coefficient, α, equals to 0.01655. From the conductivity point of view, HBCP displays dc conductivity at the low and high frequency regions that correspond to 100 Hz–12 kHz and 3.3 MHz–15 MHz, respectively. On the other hand, it has been revealed that the ac conductivity of the LC system investigated obeys Super Linear Power Law (SLPL) at the intermediate frequency domain. Copyright © 2015 John Wiley & Sons, Ltd.     

Substituent effects to the electrochromic behaviors of electropolymerized metallophthalocyanine thin films

Metallophthalocyanines (MPcs) (M = 2H⁺, Zn²⁺, Co²⁺, and Cu²⁺) bearing diethylaminophenoxy and chloro substituents at the peripheral positions (MPc-tdea-tCl) were coated on the working electrodes with the electropolymerization and tested as electrochromic materials. Altering the metal center of MPcs affected the redox activities of MPc-tdea-tCl films. All electropolymerized MPc-tdea-tCl films behaved as conductive and redox active films in different electrolyte systems. Electrochromic properties of MPc-tdea-tCl films were investigated via the voltammetric, in situ spectroelectrochemical, and in situ spectroelectrocolorimetric measurements. H ₂ Pc-tdea-tCl film did not give any electrochromic response, while ZnPc-tdea-tCl and CuPc-tdea-tCl films behave as a reasonable electrochromic material. Distinctive color changes with short response times, high optical contrast, and better optical and coulombic stabilities were only observed with CoPc-tdea-tCl film.     

A study of the relation between translational and rotational diffusion through measurement of molecular recollision

Translational and rotational diffusion rates of perdeuterated tempone (PDT) in ethanol are determined using electron paramagnetic resonance spectroscopy. The translational motion is measured on two scales: the macroscopic, as represented by the Heisenberg spin-exchange rate, and the microscopic, which entails recollisions between the same spin-exchange particle pair. The spin-exchange and recollision rates are used together to calculate the overall translational diffusion coefficient without recourse to assumptions concerning the value of the Stokes radius or collision distance. When observed as a function of solvent isothermal compressibility, the recollision time in ethanol is displaced from the common alkane curve at low temperatures but joins that curve at higher temperatures. Rotational correlation times in ethanol are obtained and show a decreasing rotation-translation coupling with increasing temperature, revealing a pattern that is qualitatively identical with respect to both collision and recollision. In comparison, an examination of PDT diffusion in toluene reveals an increasing rotation-translation coupling with increasing temperature. The contrasting behavior of the coupling in the two solvents is attributable to the degree of anisotropy in PDT rotation.     

Tyrosinase immobilized magnetic nanobeads for the amperometric assay of enzyme inhibitors: application to the skin whitening agents

The immobilization of tyrosinase onto glutaraldehyde activated streptavidine magnetic particles and subsequent retention onto a magnetized carbon paste electrode for the amperometric assay of tyrosinase inhibitors is described. Tyrosine was used as substrate as it is the first substrate in the melanogenesis process. The sensing mode is based on monitoring the decrease of the amperometric signal corresponding to the electrochemical reduction of dopaquinone enzymatically generated. This current decrease is due to the presence of inhibitors acting directly on the enzyme or inhibitors acting on the product of the enzymatic reaction, i.e. dopaquinone. The methodology is designed for the evaluation of the inhibitory potency of the most frequently used active substances in cosmetic marketed products against hyperpigmentation such as kojic acid, azelaic acid and benzoic acid. These compounds bind to the tyrosinase active center. Ascorbic acid is also investigated as it interrupts the synthesis pathway of melanin by reducing the melanin intermediate dopaquinone back to l-dopa. By comparing the obtained IC₅₀, under the same experimental conditions, the order of their inhibitory potency was: kojic acid (IC₅₀ = 3.7 × 10⁻⁶ M, K_i = 8.6 × 10⁻⁷ M), ascorbic acid (IC₅₀ = 1.2 × 10⁻⁵ M), benzoic acid (IC₅₀ = 7.2 × 10⁻⁵ M, K_i = 2.0 × 10⁻⁵ M) and azelaic acid (IC₅₀ = 1.3 × 10⁻⁴ M, K_i = 4.2 × 10⁻⁵ M) in close agreement with literature spectrophotometric inhibition data using the soluble tyrosinase.     

X-ray structural,spectroscopic and computational approach (NBO,MEP, NLO,NPA, fukui function analyses) of (E)-2-((4-bromophenylimino)methyl)-3-methoxyphenol

The title compound was isolated and investigated by experimental X-ray diffraction method and density functional theory (DFT) calculational properties and spectroscopic methodologies. The experimental investigations of the compound indicated the molecule seems to be in enol form. DFT calculations are performed both for enol and keto tautomers of the title compound. Additionally chemical activity, electronic transmission and property effect on different solvents, molecular electrostatic potential (MEP), non-linear optical properties (NLO), Mulliken population method, natural population analysis (NPA), natural bond orbital (NBO) and Fukui function analyses have been studied.     

The normalizer of

In this paper, the normalizers of , for k = 2 or 3, in the groups Γ^k of modular group Γ are given by using the concept of Γ^k axes of the set of left cosets of , on which Γ^k acts transitively, in Γ^k.     

Cooperative interval games: a survey

The (re)distribution of collective gains and costs is a central question for individuals and organizations contemplating cooperation under uncertainty. The theory of cooperative interval games provides a new game theoretical angle and suitable tools for answering this question. This survey aims to briefly present the state-of-the-art in this young field of research, discusses how the model of cooperative interval games extends the cooperative game theory literature, and reviews its existing and potential applications in economic and operations research situations with interval data.