Vibrational spectra of the adduct of 1,8-bis(dimethylamino)naphthalene with dichloromaleic acid (DMAN x DCM)

The infra-red (IR), Raman (R) and inelastic incoherent neutron scattering (IINS) spectra, particularly in low frequency region, of the title ionic adduct were studied. It is shown that all low frequency vibrations (below 200 cm(-1)) of (CH3)2N groups of protonated 1,8-bis(dimethylamino)naphthalene (DMAN)--clearly observed in IINS spectra--are sensitive to the environment, i.e. to the type of counterion forming short contacts with C-H bonds of methyl groups. The internal frequencies were also calculated by ab initio method. The results are consistent with numerous observations of the counteranion effect on the geometry of the protonated DMAN. The conclusions are compared with structural and NMR studies reported recently for the 1,8-bis(dimethylamino)naphthalene with dichloromaleic acid (DMAN x DCM) adduct. The single crystal R polarized spectra taken over the frequency range 20-3200 cm(-1) were analyzed in detail. We have shown that a substantial difference in the IR spectrum of the dichloromaleic acid (DCM) anion in the DMAN adduct and in the potassium salt results from different geometries of OHO hydrogen bonds. In the case of potassium salt the chains of longer intermolecular hydrogen bonds are formed described by means of a double minimum potential.     

Small-angle x-ray scattering studies on epoxidized butadiene-styrene block copolymers

Small-angle x-ray scattering (SAXS) and scanning electron microscopy (SEM) investigations for epoxidized butadiene-styrene (BS) block copolymers were performed. For unepoxidized copolymers, the SAXS curve exhibits a maximum which indicates that the copolymer has heterogeneity domain morphology. Using the standard theory for a two-phase system, mean distances between domains, the correlation length l _p , and the thickness of the phase boundary were calculated from the SAXS data. It was found that the epoxidation of BS copolymers decreases the ability of the copolymer to separate the individual components. As the content of the epoxide groups increases, the dimensions of the domains decrease until they disappear, the boundary between domains and the matrix becomes less and less definite, and the copolymer composes a homogeneous system. The disappearance of the two-phase structure of the BS copolymers indicates an increase in the compatibility of polystyrene and epoxidized polybutadiene. According to the method of Van Krevelen, the solubility parameters of polystyrene and epoxypolybutadiene were calculated. Small differences between these parameters support the conclusions drawn from the SAXS investigations     

Intermittency and the central limit theorem

Central limit theorem estimates of anomalous fractal dimensions of self-similar random cascades are studied. It is found that, in general, the normal approximation fails badly. A systematic series of approximations which converges to the exact result (both for the fractal dimensions and for the distribution itself) is derived for the -model. Consequences for the empty bin effect are indicated.Supported by the World Laboratory/HED and the CERN/LAA Projects     

Thermal analysis of binary and ternary systems of salicylic acid,sodium salicylate and sodium hydrogen carbonate

The thermal decompositions of binary and ternary systems of salicylic acid, monosodium salicylate, disodium salicylate and sodium hydrogen carbonate were studied by thermogravimetry and differential thermal analysis. The possibility was shown of analyzing systems involving components which react with each other upon heat treatment. Use can be made of results of this work to follow the course and extent of the reaction employed in the commercial method of manufacturing sodium salicylate and to check declared compositions of salicylate mixtures.

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Zusammenfassung Die thermische Zersetzung binärer und ternärer Systeme, die Salicylsäure, Mononatriumsalicylat, Dinatriumsalicylat und Natriumhydrocarbonat enthalten, wurde untersucht. Die Möglichkeit der Analyse von Systemen, deren Komponenten bei Hitzebehandlung miteinander reagieren, wurde gezeigt. Die Ergebnisse dieser Arbeit gestatten den Verlauf und das Ausmaß der Reaktionen zu untersuchen, welche bei dem Herstellungsverfahren von handelsüblichen Natriumsalicylat ablaufen und die deklarierte Zusammensetzung von Salicylatmischungen zu prüfen.

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Résumé Etude par thermogravimétrie et analyse thermique différentielle de la décomposition thermique de systèmes binaires et ternaires constitués d' acide salicylique salicylate monosodique, de salicylate disodique et d'hydrogénocarbonate de sodium. On montre la possibilité d'analyser des systèmes dont les composants réagissent entre eux lors du traitement thermique. Les résultats de cette étude permettent de suivre le déroulement et le degré d'avancement de la réaction utilisée dans le procédé commercial de fabrication du salicylate de sodium et de contrôler la composition déclarée des mélanges de salicylates.

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Kinetics of particle deposition in the oblique impinging jet cell

A new oblique impinging-jet (OBIJ) cell was developed, suitable for colloid deposition studies at various interfaces. In contrast to previously used orthogonal cells, the OBIJ construction makes possible direct microscope observations of particle deposition on nontransparent substrates. The cell performance was tested by studying kinetics of polystyrene latex particle deposition on mica. Two limiting cell configuration were used in the experiments: (i) the lower position (inverted microscope observation of substrate surface through air) and (ii) the upper position (observation of the substrate surface with adsorbed particles through the suspension layer). The dependence of local mass transfer rate (particle flux) on the position over the substrate surface was studied for various flow Reynolds numbers. It was demonstrated that deposition rate attained maximum at the flow stagnation point whose position was dependent on Re number. Moreover, it was shown that the local flux decreased at much slower rate when moving in the downstream direction, than for previously used impinging-jet cells. Consequently, the area of uniform transport conditions was larger, enabling more precise determination of the limiting particle flux at the stagnation-point. The dependence of the flux on Re number was systematically studied for various ionic strength of the suspension. It was demonstrated, in accordance with previous results for the ordinary impinging-jet, that the flux increased significantly for low ionic strength and high Re number. This phenomenon, referred to as the inverse salt effect, was interpreted in terms of the convective diffusion theory. The governing transport equation originating from this theory was solved numerically, for the region near the stagnation point, using the finite-difference method. These numerical solutions were used for nonlinear fitting of the flow intensity parameter dependence on the Re number. In this way the flow field in the vicinity of the stagnation point was fully characterized. It was concluded that the new cell can be exploited as an effective experimental tool for colloid deposition studies on various substrates.     

Contribution to the mechanism of liquid membrane oscillators involving cationic surfactant

It is shown that liquid membrane oscillators with cationic surfactants have more complex oscillation patterns than observed previously. The actual details of the oscillations depend strongly on the nature of the membrane material, disclosing even the presence of parallel molecular events. It appears that sampling topology also has a great influence on the observed oscillatory behavior. Variation of oscillation patterns with diffusion path length in the membrane demonstrated the decisive role played by the actual timing of molecular events. The new evidences produced complete usefully the actual views concerning the mechanism of oscillations.     

A New Complex of Europium(II) with edta – Structure and Spectroscopy

A new complex of europium(II) with ethylenediaminetetraacetic acid was obtained by electrochemical reduction. The compound is composed of polymeric chains, guanidinium cations and water molecules. The Eu²⁺ cation is eight‐coordinate (two nitrogen atoms and six carboxylate oxygen atoms), and contrary to europium(III) complexes with edta, does not contain water molecules in the first coordination sphere. Relationships between the coordination mode and IR as well as UV–Vis spectra are discussed.     

The reactions of 2-benzoylpyridine with [RuHCl(CO)(PPh3)3] and [(C6H6)RuCl2]2

The reactions of [RuHCl(CO)(PPh₃)₃] and [(C₆H₆)RuCl₂]₂ with 2-benzoylpyridine have been examined, and two novel ruthenium(II) complexes – [RuCl(CO)(PPh₃)₂(C₅H₄NCOO)] and [RuCl₂(C₁₂H₉NO)₂] – have been obtained. The compounds have been studied by IR and UV–Vis spectroscopy, and X-ray crystallography. The molecular orbital diagrams of the complexes have been calculated with the density functional theory (DFT) method. The spin-allowed singlet–singlet electronic transitions of the compounds have been calculated with the time-dependent DFT method, and the UV–Vis spectra of the compounds have been discussed on this basis.     

Theory of Nucleon-Nucleon Scattering

We present a new study of kinematical problems of relativistic nucleon-nucleon interactions, more complete than the previous studies. Two-component spinor formalism is used throughout. Several choices of spinor bases, their relations, crossing relations in all channels, helicity amplitudes, partial-wave amplitudes, the absence of kinematical singularities, and unitarity are discussed. The contributions of arbitrary intermediate states J in the unitarity are summed and the Regge forms for all five scalar amplitudes are obtained.