Thermal diffusion and molecular diffusion values for some alkane mixtures: a comparison between thermogravitational column and thermal diffusion forced rayleigh scattering

In the present work we studied the thermal diffusion behavior of n-decane in various alkanes by thermogravitational column (TC) technique and the thermal diffusion forced Rayleigh scattering (TDFRS) method. The investigated lighter alkanes compared to n-decane are n-pentane, n-hexane, n-heptane, n-octane, and the heavier ones are n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, and n-eicosane. The binary mixture n-decane/ n-pentane we investigated at several different concentrations; all other mixtures were only investigated at a mass fraction of 50%. Even for the volatile n-pentane/ n-decane mixture the deviations between the thermal diffusion coefficients determined by the different methods agreed within the error bars. Typically the agreement between the two methods was in the order of 5%. In comparison to recently published TC and TDFRS data we found deviations in the order of 30% up to 40%. We analyze and discuss the possible reasons for the discrepancies for the present and the past publications.     

Structural and electrochemical characterization of polyaniline/LiCoO2 nanocomposites prepared via a Pickering emulsion

Polyaniline (PANI)/LiCoO₂ nanocomposite materials are successfully ready through a solid-stabilized emulsion (Pickering emulsion) route. The properties of nanocomposite materials have been put to the test because of their possible relevance to electrodes of lithium batteries. Such nanocomposite materials appear thanks to the polymerization of aniline in Pickering emulsion stabilized with LiCoO₂ particles. PANI has been produced through oxidative polymerization of aniline and ammonium persulfate in HCl solution. The nanocomposite materials of PANI/LiCoO₂ could be formed with low amounts of PANI. The morphology of PANI/LiCoO₂ nanocomposite materials shows nanofibers and round-shape-like morphology. It was found that the morphology of the resulting nanocomposites depended on the amount of LiCoO₂ used in the reaction system. Ammonium persulfate caused the loss of lithium from LiCoO₂ when it was used at high concentration in the polymerization recipe. Highly resolved splitting of 006/102 and 108/110 peaks in the XRD pattern provide evidence to well-ordered layered structure of the PANI/LiCoO₂ nanocomposite materials with high LiCoO₂ content. The ratios of the intensities of 003 and 104 peaks were found to be higher than 1.2 indicating no pronounced mixing of the lithium and cobalt cations. The electrochemical reactivity of PANI/LiCoO₂ nanocomposites as positive electrode in a lithium battery was examined during lithium ion deinsertion and insertion by galvanostatic charge–discharge testing; PANI/LiCoO₂ nanocomposite materials exhibited better electrochemical performance by increasing the reaction reversibility and capacity compared to that of the pristine LiCoO₂ cathode. The best advancement has been observed for the PANI/LiCoO₂ nanocomposite 5 wt.% of aniline.     

Electron Ionization Mass Spectra of Organophosphorus Compounds Part I: The Mass Fragmentation Pathways of Cyclic α-Aminophosphonates Monoester Containing 1,2,4-Triazinone Moiety

Abstract

The electron impact induced fragmentation reactions of 3-(4-chlorophenyl)-3,4- dihydro-2-ethoxy-2-oxido-7-methyl-2H,6H-[1,2,4]triazino[4,3-e][1,4,5,2]thiadiazaphosphin in-6-one (1), 3,7-dimethyl-2-ethoxy-2-oxido-1,2,3,4-tetrahydro-6H-[1,2,4]triazino[4,3-b][1,2,4,5]triazaphosphinin-6-one (2), and 9-amino-3,7-dimethyl-4-ethoxy-4-oxido-2,3,4,9-tetrahydro-8H-[1,2,4]triazino[3,2-c][1,2,4,5]triazaphosphinin-8-one (3) are presented and compared. The 1,2,4-triazine rings have almost identical fragmentation routes. The 1,2,4-triazine rings are rather stable relative to the phosphorus rings. Therefore, fragmentation of the phosphorus rings is more favorable for the compounds than the stable 1,2,4-triazine rings.     

A mathematical analysis and elucidation of AB(2k,1ϕ) thermophotochromic kinetics: Analytical solutions using pure kinetic data and considering as unknown the rate constants,quantum yield,and both species' spectra

A new spectrokinetic method is described that determines the absolute values of all five unknown parameters (ε_A, ε_B, ?_AB, k_AB, k_BA) of AB(2k,1?) thermophotoreactive chromic systems. For the first time, solely kinetic data are used to perform complete analytical elucidations. Also, the method addresses realistic situations by considering that both absorption spectra of the reactive species are unknown and partially or totally overlap, solving the identifiability problem, and using a single set of experimental data (for the thermal and photochemical reactions). The absolute values for the five unknown parameters that make up the true kinetic solution are readily obtained by the application of five analytically defined algebraic equations. The method is independent of experimental conditions relating to initial concentration, temperature, threshold of incident light intensity, and the wavelength at which the kinetic traces are measured. The detailed mathematical algorithm also allows the determination of the reaction quantum yield at any (isosbestic and nonisosbestic) irradiation wavelength and proposes a new colorability expression for these systems. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 255–264, 2009     

On Semicomplete Cones

We give here characterizations of relatively bounded maps, of normal cones, nuclear and well based cones. We also discuss two notions of semi-complete considered by Mokobodzki.      

On the Discrete Spectrum of a Spatial Quantum Waveguide with a Disc Window

In this study we investigate the bound states of the Hamiltonian describing a quantum particle living on three dimensional straight strip of width d. We impose the Neumann boundary condition on a disc window of radius a and Dirichlet boundary conditions on the remained part of the boundary of the strip. We prove that such system exhibits discrete eigenvalues below the essential spectrum for any a > 0. We give also a numeric estimation of the number of discrete eigenvalue as a function of \fracad\frac{a}{d}. When a tends to the infinity, the asymptotic of the eigenvalue is given.     

Synthesis and properties of 7-formyl-8-hydroxyquinoline and its transition metal complexes

Summary Co^II, Ni^II, Cu^II, Cd^II and Hg^II complexes of 7-formyl-8-hydroxyquinoline (HFHQ) have been prepared, and characterized by elemental analysis, molar conductivities, electronic and i.r. spectra, and magnetic measurements. It was found that the ligand acts as a neutral monodentate or a monobasic bidentate donor. The Co^II, Ni^II and Cu^II complexes possess, respectively, tetrahedral, octahedral and square-planar structures based on their magnetic and electronic spectral data. The electrical conductivities of HFHQ and its metal complexes were measured at different temperatures and their activation energies were calculated. The values obtained for the Co^II, Ni^II, Cd^II and Hg^II complexes agree fairly well with those reported for semiconductors. The ligand was tested as a corrosion inhibitor for aluminium; the limiting concentration of HFHQ to give maximum efficiency (99.2%) is 10^–3 mole dm^–3 at 22°C. The metal-ligand ratios and apparent formation constants for the species generated in ethanol solution were determined spectrophotometrically.     

2-Dienylphenacyloxazolones and an intramolecular Diels-Alder approach to the A-B-C ring system of phenanthridone alkaloids

A general route to the A-B-C ring system of phenanthridone alkaloids is available by acylation of 2-oxa-zolone with a 2-butadienylbenzoic acid derivative, followed by an intramolecular Diels-Alder reaction and hydrolysis.