Chemical composition and antimicrobial activity of the essential oil of <Emphasis Type="Italic">Anthemis wiedemanniana</Emphasis> from Turkey

The chemical composition and antimicrobial activity of the essential oil from aerial parts of Anthemis wiedemanniana, an endemic taxon of Turkey, were investigated. Linalool (12.75%), 1,8-cineole (8.49%), hexadecanoic acid (6.09%), and chrysanthenone (5.67%) were found to be the main components among the 122 compounds characterized in the essential oil of Anthemis wiedemanniana. Antimicrobial activities were reported against 12 microorganisms and five yeast-like fungi by the disc diffusion method. Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 40–43, January–February, 2007.     

Production of glycerides from glycerol and fatty acids by native lipase ofNigella sativa seed

The possible application of native lipase ofNigella sativa seed in the esterification of fatty acids to glycerol was investigated, and the effect of process parameters and the enzyme selectivity on the reaction were determined. For this aim, the esterification of oleic acid, sunflower oil fatty acids, and coco oil fatty acids with glycerol were studied.     

Photoacoustic method for the measurement of the thermal diffusivity of drawn foils

A nonstationary method to measure the thermal diffusivity of polymer foils with thicknesses between 10 and 40μm normal to the foil plane is described. The principle of the experimental technique is a modification of the photoacoustic effect. The quantity that is measured, is the phase angle between the modulation of the light intensity and the pressure variation as a function of frequency. A theoretical treatment of the phenomenon is presented which enables the evaluation of the diffusivity from the experimental data. It is possible to measure absolute values of the thermal diffusivity with an accuracy in the order of three percent and relative changes in the thermal diffusivity, e. g. by drawing, of one percent. Measurements were performed on commercial PETP foils of 19 and 30μm thickness drawn along various directions. For draw ratios up to 1.3 the diffusivity decreased about 20 percent or increased about 10 percent, depending on the foil thickness and the treatment during manufacture. The results can be interpreted with the aggregate model of Kilian and Pietralla as well as with the two-phase model of Choy and Young.     

COMPOSITION OF THE ESSENTIAL OIL OF Arbutus unedo

Water-distilled essential oil from leaves ofArbutus unedoL. of Turkish origin was analyzed by GC/MS. Thirty-seven constituents were characterized with (E)-2-decenal (12.0 %), -terpineol (8.8 %), hexadecanoic acid (5.1 %), and (E)-2-undecenal ( 4.8 %) as the major constituents.     

Adsorption and Corrosion Inhibition Effect of 1,1′-Thiocarbonyldiimidazole on Mild Steel in H2SO4 Solution and Synergistic Effect of Iodide Ion

The inhibition effect of 1,1′-thiocarbonyldiimidazole (TCDI) on the corrosion behaviors of mild steel (MS) in 0.5 mol·L⁻¹ H₂SO₄ solution was studied with the help of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and linear polarization resistance (LPR) techniques. The effect of immersion time on the inhibition effect of TCDI was also investigated over 72 h. For the long-term tests, hydrogen evolution with immersion time (V_H2-t) was measured in addition to the three techniques already mentioned. The thermodynamic parameters, such as adsorption equilibrium constant (K_ads) and adsorption free energy (ΔG_ads) values, were calculated and discussed. To clarify inhibition mechanism, the synergistic effect of iodide ion was also investigated. The potential of zero charge (PZC) of the MS was studied by electrochemical impedance spectroscopy method, and a mechanism of adsorption process was proposed. It was demonstrated that inhibition efficiency increased with the increase in TCDI concentration and synergistically increased in the presence of KI. The inhibition efficiency was discussed in terms of adsorption of inhibitor molecules on the metal surface and protective film formation.     

Water‐Mediated Surface Diffusion Mechanism Enables the Cold Sintering Process: A Combined Computational and Experimental Study

The cold sintering process (CSP) densifies ceramics at much lower temperatures than conventional sintering processes. Several ceramics and composite systems have been successfully densified under cold sintering. For the grain growth kinetics of zinc oxide, reduced activation energies are shown, and yet the mechanism behind this growth is unknown. Herein, we investigate these mechanisms in more detail with experiments and ReaxFF molecular dynamics simulations. We investigated the recrystallization of zinc cations under various acidic conditions and found that their adsorption to the surface can be a rate‐limiting factor for cold sintering. Our studies show that surface hydroxylation in CSP does not inhibit crystallization; in contrast, by creating a surface complex, it creates an orders of magnitude acceleration in surface diffusion, and in turn, accelerates recrystallization.     

Inhibition of paraoxonase 1 by coumarin‐substituted N‐heterocyclic carbene silver(I), ruthenium(II) and palladium(II) complexes

We synthesized three coumarin‐substituted benzimidazolium chlorides and their silver(I), ruthenium(II) and palladium(II) N‐heterocyclic carbene (NHC) complexes. All compounds were characterized using appropriate spectroscopic techniques and elemental analyses. Single‐crystal X‐ray structure of a Pd(II)–NHC complex ( 6b ) was also determined. The inhibitory properties of all compounds were tested on the activity of human paraoxonase 1 (PON1). All complexes exhibited weaker inhibitory properties than their corresponding benzimidazolium salts except for complex 6b which is the most active inhibitor with an IC₅₀ value of 3.01 μM among the compounds reported in this study. A kinetic evaluation showed that this complex inhibits PON1 activity in a non‐competitive manner. Molecular docking studies were also performed for 6b in order to obtain more insight into the binding mode.