Titanate nanotubes (TiNTs) were obtained by hydrothermal treatment of anatase powder in aqueous NaOH solution and then modified with 2,9,16,23-tertracarboxyl phthalocyanine copper(II) (CuPc). This hybrid organic–inorganic nanoscopic system was characterized by X-ray diffraction, microscopy, and spectroscopy. Transmission electron microscopy (TEM) images of pure and modified TiNTs revealed multiwall structures with an average outer diameter of 9 nm and a length of several hundred nanometers. The tubular morphology of the TiNTs was covered with CuPc-film. The amount of CuPc adsorbed onto the TiNTs was quantified by electron paramagnetic resonance (EPR). Using the same technique and spin-trapping methodology, the photogeneration of reactive oxygen species (ROS) from the TiNTs was systematically investigated. A drastic quenching of photoactivity was observed in the CuPc/TiNT hybrid system. Electron transfer from excited CuPc states to the TiNT conduction band followed by electron recombination may be the cause of this quenching.
The present paper deals with the immobilization of redox mediators and proteins onto protected porous silicon surfaces to obtain their direct electrochemical reactions and to retain their bioactivities. This paper shows that MP-11 and viologens are able to establish chemical bonds with 3-aminopropyltriethoxylsilane-modified porous silicon surface. The functionalization of the surfaces have been fully characterized by energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS) to examine the immobilization of these mediators onto the solid surface. Amperometric and open circuit potential measurements have shown the direct electron transfer between glucose oxidase and the electrode in the presence of the viologen mediator covalently linked to the 3-aminopropyltriethoxylsilane (APTES)-modified porous silicon surfaces.
A theoretical multiscale approach combining density functional theory and four-flux calculations based on the radiative transfer theory is used to prospect the optical properties of nanocomposite materials composed of inorganic nanoparticles of lanthanum-containing compounds (LaF 3 or LaPO 4 ) embedded in Poly(methyl methacrylate) (PMMA). This theoretical investigation shows that a potential route to produce lead-free x-ray shielding screens with high transparency in the visible range (>70% of incident light) may consist in incorporating colorless LaF 3 or LaPO 4 spherical particles with a diameter lower than 6 nm in a PMMA panel from a minimum thickness of 3 mm with a volumetric fraction of at least 10%. In terms of x-ray attenuation, this would lead to lead equivalency of 0.1 mm (lead foil).
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