Şefik Süzer

IR AND TURBIDITY STUDIES OF VITAMIN E-CHOLESTEROL-PHOSPHOLIPID MEMBRANE INTERACTIONS

Binary and tertiary mixture of α-tocophenol, cholesterol and dimyristoylphosphatidylcholine in the form of multilamellar liposomes were investigated by Fourier Transform Infrared and visible spectroscopy. Results of the FTIR and turbidity experiments indicate that α T decreases or diminishes the effect of cholesterol on the frequency and the bandwidth of the C-H stretching, CH2 scissoring and C=O stretching bands in FTIR spectra and the turbidity measurements (recorded as absorbance values at 440 nm) in phospholipid model membranes.

Doping of 2-Cl-PANI/PVC films by exposure to UV, γ-rays and e-beams

Abstract 2-Chloro-polyaniline (2-Cl-PANI) is chemically prepared in its non-conducting (Emeraldine Base, EB) form and dissolved together with polyvinylchloride (PVC) in THF for casting into thin (10–50 μm) composite films. The electrical conductivity of these films increases by more than four orders of magnitude (from 10 −6 to 10 −2 S/cm) when they are exposed to UV, γ-rays and e-beams. This is attributed to the dehydrochlorination (loss of HCl) of PVC by exposure to energetic particles and subsequent doping of the 2-Cl-PANI (i.e., conversion to Emeraldine Salt, ES) by the in-situ-created HCl. The doped films can also be returned to their undoped form by further exposure to NH 3 vapours. The UV (or other particles)-induced doping/NH 3 undoping cycles can be repeated several times until almost total dehydrochlorination of the PVC matrix. UV–Vis–NIR, Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopic (XPS) techniques are employed to follow the changes in the composite films upon doping by exposure to these energetic particles.

Electrochemically generated catalyst system with increased specificity and efficiency for olefin metathesis

Abstract A facile route for the electrochemical generation of an olefin metathesis catalyst from methylene chloride solution of WCl 6 was described. It was found that reductive, oxidative and pulse electrolysis produced the same intermediate. This electrolysis intermediate incorporates olefin into its structure possibly forming a metal–olefin complex, which decomposes into catalytically active metal carbene type species. ESCA, NMR and ESR methods were used to elucidate the structure of the catalyst system. The catalyst was applied in the metathesis of 1-octene and 2-octene without any need for a co-catalyst. Highly specific products with high yields were obtained.

XPS investigation of thin SiOx and SiOxNy overlayers

Abstract Angle-resolved XPS is used to determine the thickness and the uniformity of the chemical composition with respect to oxygen and nitrogen of the very thin silicon oxide and oxynitride overlayers grown on silicon.

XPS and in-situ IR investigation of RuSiO2 catalyst

Abstract Ru ( NO )( NO 3 ) 3 SiO 2 catalyst precursors were characterized via XPS and in-situ reflectance IR spectroscopy before, during and after reduction by hydrogen over the temperature range 300–800 K. IR results indicated that the catalyst precursor lost NO 3 groups first, with subsequent loss of NO both in a reducing atmosphere and during thermal annealing. XPS was used to derive information on the oxidation state of Ru in the various steps of the annealing and/or reduction processes.

Analysis of SF6 Discharge by Optical Spectroscopy

Optical emission spectra of SF6 and CF3H and mixtures of them containing nitrogen have been examined in the 250–600 nm range under positive and negative high voltages. In SF6 discharge nitrogen impurity lines dominate the spectrum although features due to F and S atomic and ionic emission and a new molecular emission band around 420–500 nm are observable. It is found that the polarity of the electrode has a profound effect on the characteristics of the emission and favors nitrogen in negative polarities. The same effect, to a lesser degree, is observable in CF3H discharges as well.

Composition of γ-ray induced triethoxyvinylsilane-methyl methacrylate copolymers determined by XPS

Methyl methacrylate (MMA) was copolymerized with triethoxyvinylsilane (TEVS) using 60Co-γ radiation at varying masses of the liquid monomers in the feed. Their homopolymers PMMA and PTEVS were also prepared by the same method. Thin copolymer and homopolymer blend films were prepared by dissolving the polymers in tetrahydrofuran and casting on clean Teflon or glass substrates. Analysis of the surface composition of these films using XPS indicated that the surfaces of the blend films were completely covered by PTEVS after 10% composition by weight. Similar analysis on the copolymer films, however, revealed that the surfaces of the copolymers contain comparable amounts of PMMA and PTEVS in agreement with the bulk analysis using infrared spectrometry. Hence, use of PMMA/PTEVS copolymers for stone preservation seems feasible by radiation induced polymerization.

HIGH-VOLTAGE OPTICAL EMISSION IN BINARY GASEOUS MIXTURES OF N2

Abstract Optical emission in 1:1 binary gaseous mixtures under high voltage displays a varying character depending on pressure, applied voltage polarity, and chemical nature of the mixture. Under negative polarity, in pure N 2 and 50% mixture of Ar, O 2 and CO 2 , emission stemming from N 2 + is enhanced relative to emission from neutral N 2 . In mixtures of N 2 with gases containing halogens (CCl 4 , CHCl 3 , CH 2 Cl 2 , CF 3 H, CF 2 Cl 2 and SF 6 ) a reversal is observed, i.e. the N 2 + emission is suppressed. An enhancement factor is defined as the ratio of the emission under negative polarity to positive polarity to quatify this polarity dependence. This enhancement factor varies between 0.01 and 50 depending on the second component in the mixture.