Band 228, Heft 1 -

Expressions for representing the pressure dependence of unimolecular dissociation and the reverse recombination reactions are compared. Situations are considered where the broadening of the corresponding falloff curves is particularly pronounced, i.e. where broadening factors at the center of the falloff curves, F cent , are very small and falloff curves correspondingly become very “broad”. Such situations arise when unimolecular reactions of molecules with large numbers of low-frequency modes and high-temperature situations are considered. Recombination reactions of polyatomic species in atmospheric chemistry and dissociation reactions of large molecules in combustion are the fields of application of the present results. While previously proposed expressions for asymmetric broadening factors showed artifacts when F cent decreased to values below about 0.4, alternative functions are described which avoid these problems for situations where F cent decreases to values far below 0.1.

In the last decades, many attempts have been made to investigate influence quantities on the formation of contact angles and their interpretation. The effect of gravitation on the measured contact angles is a controversially discussed mater. In 1876 J. W. Gibbs already formulated conditions for equilibrium and therefore even for the equilibrium contact angle θ e which describe the acting gravitational field on a fluid component. Nevertheless, these relations often are not considered. The presented study illustrates differences between the apparent contact angles of sessile drops which are obtained by dynamical measurements with the inclined-plate and the needle-in method. This fact demonstrates that the force distibution at the triple line additionally differs in dependence on the used measuring method. The force distribution at the triple line depends on the relative position in the gravitational field (e.g. inclined or horizontal sample position) and on the curvature of the liquid-vapour interface (interfacial tension). Hence, theses effects on the apparent contact angles have to be considered for a reasonable interpretation of the measurement data. For this purpose, an approach to describe the effect of forces related to gravity effects on contact angles will be presented.

A series of SnO 2 -Al 2 O 3 composite metal oxide supports with different Sn/Al atomic ratios were synthesized with co-precipitation method and used as supports for Pd to prepare catalysts for CO oxidation. The samples were characterized by N 2 adsorption-desorption, CO adsorption-desorption, X-ray Powder Diffraction (XRD), H 2 temperature programmed reduction (H 2 TPR), and X-ray photoelectron spectroscopy (XPS) techniques. It was found that Al 3+ can be introduced into the crystalline lattice of tetragonal rutile SnO 2 to effectively form solid solution structure. As a consequence, SnO 2 -Al 2 O 3 binary supports with significantly improved thermal stability, enlarged surface areas, enhanced texture structure and containing more active surface oxygen species can be obtained. SnAl73, a support with a Sn/Al atomic ratio of 7/3, was found to be the best support in this study due to its certain large surface area and the presence of suitable amount of reducible oxygen species. With this support, the two major reasons accounting for the activity, that is, Pd dispersion and strong metal support interaction (SMSI) between Pd and the support, is believed to be tuned optimally. Water vapor has reversible effect on the CO oxidation activity of Pd/SnAl73 catalyst, but which is mitigated evidently by the presence of SnO 2 . In addition, no any permanent deactivation occurs to Pd/SnAl73 catalyst during a 60 hours' test in the presence or absence of water vapor, indicating this optimized SnO 2 -Al 2 O 3 support has a strong potential to be applied in some practical processes for exhaust clean. In summary, SnO 2 -Al 2 O 3 composite metal oxides with suitable Sn/Al atomic ratios are better supports than individual Al 2 O 3 and SnO 2 , on which less amount of Pd could be used to achieve supported Pd catalysts with rival performance.

Bauxite with a large surface area was successfully prepared from natural bauxite using a hydrothermal process. Both 0.5% Pd/bauxite and 0.5% Pd/Al 2 O 3 catalysts were prepared using an incipient-wetness impregnation method for CO oxidation reaction. The characteristics of the samples were determined by X-ray fluorescence, low temperature N 2 physical adsorption, X-ray diffraction, transmission electron microscopy, H 2 temperature-programmed reduction and X-ray photoelectron spectroscopy. The average pore diameter, BET surface area and pore volume of the bauxite support at the optimum hydrothermal conditions of temperature (170 ○ ) and time (72 h) were found to be approximately 4.82 nm, 153 m 2  g – 1 and 0.23 cm 3  g – 1 , respectively. The activity of the 0.5% Pd/bauxite catalyst was much higher than that of the 0.5% Pd/Al 2 O 3 catalyst, it's due to that Fe 2 O 3 itself contained in bauxite was a good catalyst for CO oxidation and can interact with Pd in the catalyst.

(E)-benzil monoxime (or (E)-monoxime of 1,2 diphenyloetandion), which is the subject of this paper, belongs to the family of bioactive organic substances. Many of them have been investigated for many years by inelastic, incoherent neutron scattering spectroscopy (IINS) but the investigation of (E)-benzil monoxime is absent from literature. Therefore (E)-benzil monoxime has been investigated using infrared, and IINS spectroscopy. Dimers of (E)-benzil monoxime were considered using B3LYP functional (connection of Becke and Lee–Yang–Parr functionals) combined with the 6-311++G(d,p) basis set method of quantum chemistry in order to improve the results obtained for a single molecule. In (E)-benzil monoxime, extra bands corresponding primarily to hydrogen bond vibrations ( γ bending out of plane of hydrogen bond at 312.3, 372, 470.5, 578.3, 703.5, 748.7, 780.4 cm – 1 , σ stretching of hydrogen bond bridge at 124.3, 140.9, 176.5, 190.1, 223.6, 259.1, 290.5, 501.8, 623.5 cm – 1 , δ bending in plane of hydrogen bond at 1102.4, 1371,1452,1535, 1630.6 cm – 1 , λ bending of hydrogen bond bridge at ca. 40 cm – 1 , ν stretching band OH at 3397 cm – 1 ) have been identified. Some of them could be discovered only by using IINS method and this is the main result of this work. Additionally we'd like to compare the structure of the compound and the structure of oximes previously investigated by us . Taking into account the structure and IINS results for three oximes investigated by us, we can estimate the difference of hydrogen bond power in those three oximes. Hence the power of hydrogen bond in the (E)-benzil monoxime seems to be the smallest in the group of the three compounds: (E)-benzil monoxime, (E)-2-hydroxyimino-2-cyanoacetic acid ethyl ester (2-oxime), acid K salt of 2-oxime.

Sound velocities ( v ) and densities ( d ) for some alkali metal chlorides in aqueous solutions containing 0, 0.001, 0.005 and 0.01 M Furosemide have been measured at different temperature (293, 303 and 313 K). The data was used to apparent molar volume ( ϕ v ) and apparent molar adiabatic compressibility ( ϕ k ). The above calculated parameters were found to be sensitive to the prevailing in the Furosemide-Na + /K + -water system. These parameters have been examined as a function of Furosemide concentration and temperature to understand the consequences of interactions between these two components. Debye Hückel limiting law is used for the assessment of the contributions of various types of solute-solvent interactions. Viscosity B -coefficients have also been evaluated for these salts in the presence of Furosemide. Jones–Dole viscosity equation is used to calculate viscosity B -coefficient which is known to provide information concerning the solvation of ions and their effects on the structure of the solvent in the near environment of the solute particles. It is related to measure the solute–solvent interaction and is interpreted in terms of the solvent structure-making and breaking effect of the electrolyte in solution. A reasonably good qualitative correlation is found to exist with regard to the Furosemide-Na + /K + interaction obtained from the experimental data, from different techniques.

Density functional theory calculations were used to analyze the interactions in 1 : 1 and 1 : 2 complexes of naphthalene (NAP) with dimethyl ether (DME). The structures of complexes have been determined using M05-2X density functional and the aug-cc-pVDZ basis set. The structures obtained were analyzed with the quantum theory of atoms in molecules (QTAIM), the energy decomposition analysis, and many-body interaction energies methodologies. Two minima were located on the potential energy surface of the 1 : 1 complexes. Four different structures have been obtained for the 1 : 2 complexes. Two types of interactions are observed, CH⋯O and CH⋯ π hydrogen bonds. Interaction energies of the 1 : 1 and 1 : 2 complexes are in the range 9–12 kJ mol – 1 and 20–27 kJ mol – 1 , respectively, at the M05-2x/aug-cc-pVDZ level of theory.