Volume 230, Issue 1

The rotational spectra of the two structurally related molecules, 1,4-cineole and 1,8-cineole (eucalyptol), were measured between 2–8.5 GHz with chirped pulse Fourier transform microwave spectroscopy. The structures of these two molecules only differ in the connectivity of an ether functional group. This results in a significant change in the three dimensional structure of the molecule and consequently large differences in the rotational spectra. Only one conformer of each molecule was detected in the molecular jet and no line splittings due to internal rotations were detected. A substitution structure ( r s ) was determined for eucalyptol and benchmarked to quantum chemical structures allowing for a comparison of eucalyptol and 1,4-cineole.

An empirical interatomic potentials for the interaction of Hg with inert gases are developed by simultaneously fitting the modified Tang–Toennies (MTT) potential function to spectroscopic data, thermo-physical and transport properties over a wide temperature range. The two-body anisotropic collision-induced light scattering spectra of mercury vapor with mixtures of rare gas has never been measured. The lineshape calculations through quantum mechanical methods have been used to predict a reasonable experimental spectra of the induced light scattering at T  = 500 K using these models of potentials and a suitable models for the anisotropy. The results of calculations show that these models of the interactions and the induction mechanisms are the most accurate models reported to date for these mixtures.

Nickel-copper-phosphorous layers were electro-less deposited on the surface of anodized aluminum and aluminum alloys. The electrochemical behavior of the improved surface was investigated in 0.5 M Na 2 SO 4 . The corrosion resistance of the modified alloy's surface is ten folds that measured on the anodized materials. The surface morphology was examined by scanning electron microscopy, SCE, and the deposit composition was subjected to x-ray energy dispersive analysis, EDAX. The experimental impedance data were fitted to theoretical data according to a proposed equivalent circuit model. The results show that the Ni–Cu–P layer was deposited homogeneously on the anodized Al surface but on the anodized-alloy surface the layer had a defective nature.

A mechanistic approach to the influence of Mn(II) catalyzed oxidative deamination of an anti-convulsant drug [GP] by peroxomonosulphate (PMS) at a constant ionic strength of 1.0 mol dm – 3 have been studied, spectrophotometrically. The reaction shows first order dependence on [PMS] and [Mn(II)] and apparent less than unit order dependence each in [GP] and alkali concentrations. Influence of dielectric constant and ionic strength of the medium on the reaction rate have been evaluated. It was observed that the added sulphate ion, the reduction product of the oxidant, had insignificant effect on the reaction rate. The reaction stoichiometry and oxidation products deprotonated GP, SO 4 2− and MnO 2 have been identified and a suitable mechanism has been proposed. The reaction fails to initiate polymerization in the presence of acrylonitrile under the experimental conditions employed. In a composite equilibrium step, deprotanated GP binds to catalyst and form a complex C that subsequently decomposes with oxidant to yield the products. Investigations of the reaction at different temperatures allowed the determination of the activation parameters and a tentative reaction mechanism in good consistency with the kinetic results is discussed.

The inhibition behavior of Polyoxyethylene (20) sorbitan monooleate (Tween 80) as a non-toxic corrosion inhibitor for aluminum alloy (A5754) was investigated in 0.5 M NaOH solution by means of polarization measurement and quantum chemistry method. A significant inhibition in the corrosion rate of A5754 in NaOH solution was observed in the presence of Tween 80. As a result of adsorption of the inhibitor on the metal surface, the inhibition of this compound increases with its concentration but decreases with temperature. Polarization curves showed that Tween 80 acted as mixed inhibitor. The adsorption of Tween 80 obeys the Langmuir adsorption isotherm. Comprehensive adsorption (physisorption and chemisorption) of the inhibitor molecules on the A5754 surface was suggested based on the thermodynamic adsorption parameters. Correlation between quantum chemical calculations and inhibition efficiency of the investigated compounds was discussed using DFT method.

Diagnostic criteria for growth of the anodic oxide film on platinum in KOH are reported. In this work, the analytical analysis of oxide film growth demonstrated that the electric field in the passive film formed anodically on platinum in KOH is constant, independent of the applied voltage and barrier layer thickness. This criterion intrinsically distinguishes the Point Defect Model (PDM) from the High Field Model (HFM). Unequivocally, the PDM provides a superior theoretical framework than does the HFM for interpreting oxide film growth on platinum. Importantly, we argue that the diagnostic criteria also apply to metal interstitial conduction, which is the mechanism proposed in the HFM for formation of the PtO oxide film on platinum, but with film growth occurring at the film/solution interface and with a thickness-dependent electric field, rather than being restricted to oxygen vacancy conductors alone, as originally derived for the PDM. Thus, the ability of the diagnostic criteria to differentiate between the HFM and the PDM, in this case, is a direct assessment of the dependence of the electric field strength on the applied voltage and barrier layer thickness, with the experimental results coming down unequivocally on the side of the PDM.

Three kinds of 4-hydroxycoumarin derivatives, namely, biscoumarins (1–4), epoxydicoumarins (5–8) and dihydropyrans (9–12), were synthesized and the antibacterial activity of each of them was evaluated. The result of preliminary bioassay shows that the lowest minimal inhibitory concentration (MIC) of compounds 1 and 2 against drug-sensitive S. aureus (ATCC 29213) and methicillin-resistant S. aureus (MRSA XJ 75302, Mu50, ATCC 700699 and USA 300) is 4–64 ug/mL. Additionally, there are two classical intramolecular O—H⋯O hydrogen bonds (HBs) in the structures of biscoumarins (1–4), and their corresponding HB energies were further calculated by the density functional theory (DFT) [B3LYP/6-31G*] method.

Pristine hydrophilic silica aerogel nanoparticles surface was functionalized with hexamethyldisilazane (HMDS). Then, the resultant modified nanoparticles were used for in situ polymerization of styrene by activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) to synthesize well-defined polystyrene nanocomposites. Success surface modification of hydrophilic silica aerogel nanoparticles with HMDS is demonstrated by FTIR spectroscopy and TGA. Nitrogen adsorption/desorption isotherm is applied to examine surface area and structural characteristics of the synthesized hydrophobic silica aerogel nanoparticles. Evaluation of size distribution and morphological studies were also performed by SEM and TEM. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography respectively. Adding of hydrophobic silica aerogel nanoparticles by 3 wt % results in a decrease of conversion from 89 to 64%. Molecular weight polystyrene chains decreases from 53991 to 42701 g · mol – 1 by addition of 3 wt % hydrophobic silica aerogel nanoparticles; however, polydispersity index values increases from 1.22 to 1.6. A peak around 4.15 ppm which originates from hydrogen atom of terminal units of polystyrene chains in proton nuclear magnetic resonance spectra can appropriately demonstrate the living nature of the polymerization. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows a decrease in glass transition temperature from 80.3 to 68.9 ℃ by addition of 3 wt % hydrophobic silica aerogel nanoparticles.