Absolute rate constants for the reactions ofOHradicals withCH3CH2OH, CF2HCH2OHandCF3CH2OH

Summary Pulsed laser photolysis with resonance fluorescence monitoring of OH radicals was applied at T = 300±2 K to obtain the rate constants of k₁= (3.38±0.60)x10^-12, k₂= (2.52±0.44)x10^-13and k₃ = (1.06±0.30)x10^-13cm³molecule^-1s^-1with 2σprecision given for the overall reactions OH + CH₃CH₂OH (1), OH + CF₂HCH₂OH (2) and OH + CF₃CH₂OH (3), respectively. k₂is the first direct kinetic data for the reaction of OH radicals with CF₂HCH₂OH reported in the literature.</o:p>     

One-wavelength in-plane rotation analysis in electronic speckle pattern interferometry

The analysis of in-plane rigid-body rotations requires phase-shifting methods to determine the direction of rotation in conventional electronic speckle pattern interferometry (ESPI). The phase-shifting procedure makes the real-time measurements impossible. A quasi-real-time method is published recently, where the usual symmetric illumination is combined with a wavelength change before the second exposure. The present paper proposes a device sparing an alternative to this. The symmetric illumination is retained but the wavelength change is replaced by simple illumination direction changes.     

Differential potentiometric titrations of binary mixtures of halides with two ion-selective indicator electrodes

Differential potentiometric titrations with two different ion-selective indicator electrodes are described. Ion-selective electrodes for Cl^-, Br^-, I^-, F^-, S^2-, as well as glass and silver billet electrodes were used. The method was tested in the determination of binary mixtures of halides (Cl^-, Br^-, I^-, and F^-) by titration with solutions of silver nitrate, alone and mixed with lanthanum or thorium nitrate as required. Various factors influencing the determination were investigated. Results of simultaneous determinations of mixtures were in good agreement with the results of separate determinations within certain concentration limits. The method was successfully applied to the determination of a four-component halide mixture. Titrations of mixtures of fluoride with thiocyanate or hexacyanoferrate(III), and some other possibilities, are also reported.     

Characterization of the liquid product recovered through pyrolysis of PMMA-ABS waste

Thermal decomposition of waste polymethylmethacrylate-acrylonitrile-butadiene-styrene (PMMA-ABS) blend has been carried out using analytical and lab-scale pyrolysis methods in order to identify the substantial components appearing in the liquid product. Additionally decomposition characteristics of the blend have been investigated regarding the possible interrelation between the two components during the pyrolysis. The interactions between PMMA and ABS seem to modify the decomposition characteristics of the ABS, resulting in a lower degradation temperature than that of pure ABS. Moreover the simultaneous decomposition results in recombination of the products yielding new volatile compounds. During batch pyrolysis relatively high amount of gas production was observed, that is in contradiction with the results obtained by analytical pyrolysis and the data found in the literature where pyrolysis of the PMMA as well as the ABS was reported to yield low amount of gas products. The liquid product retrieved from thermal decomposition has been analyzed with respect to the possible utilization as a propellant. Hence aside from the investigation of contained elements and compounds, determination of density, viscosity, research octane number (RON), calorific value, and gaseous emissions has been carried out as well. The relatively high yield (65 wt%), and outstanding compression tolerance (RON = 110.2) observed at the pyrolysis oil make it a feasible fuel admixture.     

Convexity of the zeros of some orthogonal polynomials and related functions

We study convexity properties of the zeros of some special functions that follow from the convexity theorem of Sturm. We prove results on the intervals of convexity for the zeros of Laguerre, Jacobi and ultraspherical polynomials, as well as functions related to them, using transformations under which the zeros remain unchanged. We give upper as well as lower bounds for the distance between consecutive zeros in several cases.     

Saturated heterocycles. 242. Synthesis of 2-substituted-6-(6′,7′-dimethoxy-3′,4′-dihydro-1′-isoquinolyl)-5,6,7,8-tetrahydro- quinazolin-4(3H)-one Derivatives

In the reactions of the recently synthesized β-ketoesters 1-[(3′-methoxycarbonyl- and 1-[(3′-ethoxycarbonyl-4′-oxo)-1′-cyclohexyl]-3,4-dihydroisoquinoline 4, 5 with amidines or cyclic guanidines, a number of 2-substituted-6-(6′,7′-dimethoxy-3′,4′-dihydro-1′-isoquinolyl)-5,6,7,8-tetrahydroquinazolin-4(3H)-one derivatives 6–8 were prepared. The new compounds possess various pharmacological actions.     

High-efficiency aminocarbonylation by introducing CO to a pressurized continuous flow reactor

Halogenated aryl carboxylic acids were efficiently converted to the corresponding dicarboxylic acid monoamides by a one-step Pd-catalyzed aminocarbonylation in a micro/meso fluidic continuous flow reactor (X-Cube) operated at high pressure and high temperature with CO gas introduction. Reaction parameters (solvent, base, catalyst, pressure, temperature) were rapidly optimized in the reactions, which required less than 2 min. The method gave improved results over comparable batch techniques and is also suited to automated parallel syntheses of compound libraries.     

The quaternary complex Hadamard matrices of orders 10, 12, and 14

A complete classification of quaternary complex Hadamard matrices of orders 10, 12 and 14 is given, and a new parametrization scheme for obtaining new examples of affine parametric families of complex Hadamard matrices is provided. On the one hand, it is proven that all 10×10 and 12×12 quaternary complex Hadamard matrices belong to some parametric family, but on the other hand, it is shown by exhibiting an isolated 14×14 matrix that there cannot be a general method for introducing parameters into these types of matrices.     

The main elementary events of degradation and stabilization of PVC

The fundamental aspects of PVC degradation and stabilization are discussed. The primary process of thermal degradation (initiation, zip-elimination of HCl and simultaneous formation of polyene sequences, and termination of unzipping) is reevaluated in the light of results obtained with PVCs containing increased concentrations of labile chlorines. The effect of these defects on thermooxidative stability of the resin is also discussed. It has been shown that results obtained in recent systematic stabilization studies cannot be explained by the widely accepted Frye-Horst mechanism, i.e., substitution of labile chlorines by stabilizers. A new mechanistic proposition, the reversible blocking mechanism, for the stabilization of PVC is presented, and the effect of stabilizing reactions on the main elementary events of thermal and thermooxidative degradation is described in a unified manner.