No abstract

For a better understanding of the oxide growth and final film properties upon anodization of titanium in sulfuric and phosphoric acid containing electrolytes, the electrochemical behavior as studied by a.c. impedance was correlated to microstructural analysis (TEM, Raman). Chemical depth profiling of the films was performed with glow discharge optical emission spectroscopy (GDOES), XPS and RBS. The fitted capacitances and resistances from a.c. impedance measurements were greatly influenced by the ongoing crystallization as well as by film porosity as a function of increasing anodization potential. GDOES revealed a small sulfur contamination (with its maximum before the oxide-metal interface) upon anodization in 1 M H 2 SO 4 and a significant phosphorus content throughout the oxides for films grown in 1 M H 3 PO 4 , showing an accumulation at the surface. Small impurities of carbon in all films as well as an accumulation of hydrogen at/after the interface oxide-metal were also observed. Quantification of the hydrogen content by elastic recoil detection analysis (ERDA) indicated a peak concentration of 20-30 at%.

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The fluid flow in a radio-frequency induction thermal plasma (RF-ITP) system for the synthesis of nanoparticles has been characterized using three-and two-dimensional modelling supported by enthalpy probe and calorimetric measurements in order to provide insights for the improvement of the process. The RF-ITP system is composed of a commercial inductively coupled plasma torch mounted on a reaction chamber that is equipped with viewports for diagnostics. The three-dimensional model predicted an almost axisymmetric temperature field in the reaction chamber in agreement with enthalpy probe measurements performed along two perpendicular scan axes, whereas recirculating flow patterns resulted in being strongly non-axisymmetric. Temperature profiles at two distances (60 mm and 100 mm) from the torch outlet have been calculated using two-dimensional modelling and compared with enthalpy probe measurements for different operating conditions with the aim of validating the predictive ability of the modelling tool. Calorimetric measurements have been performed in order to estimate the power coupled to the torch, which is usually an arbitrary input parameter for the models. Poor agreement was obtained between energy balances from modelling and from calorimetric measurements and, starting from this, a discussion on the uncertainties in the calculation of the radiative losses has been proposed. Finally, new insights for the improvement of the process of nanoparticle synthesis in the RF-ITP system are suggested.

SRI 62-834, an analog of the antitumor agent ET-18-OCH3 in which the oxygen atom at carbon atom 2 has been incorporated into a five-membered heterocycle, has been prepared and evaluated as an antitumor agent. The compound exhibited good cytotoxicity in vitro against a variety of tumor cell lines and was as effective as ET-18-OCH3 given orally in the mouse Meth A sarcoma model. SRI 62-834 was shown to be an inhibitor of platelet-derived growth factor (PDGF), possibly at the receptor level, and platelet-activating factor (PAF) at the receptor level.