Deep Impact? On 15 February 2013, the Russian district of Chelyabinsk, with a population of more than 1 million, suffered the impact and atmospheric explosion of a 20-meter-wide asteroid—the largest impact on Earth by an asteroid since 1908. Popova et al. (p. 1069 , published online 7 November; see the Perspective by Chapman ) provide a comprehensive description of this event and of the body that caused it, including detailed information on the asteroid orbit and atmospheric trajectory, damage assessment, and meteorite recovery and characterization.

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The catalytic activity of nanotubular titanium dioxide films formed during the oxidation of acetone to carbon dioxide under the action of visible light with a wavelength of 450 nm was found to be approximately 2 times higher compared to standard titanium dioxide (Degussa P25). The nanotubular films were grown by the anodization of titanium foil using an original technique. Diffuse reflectance spectra of the films are attributed to enhanced activity in the visible spectrum by the nonstoichiometry of titanium dioxide near the interface between the nanotubular film and the titanium foil substrate.

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The influence of UV radiation at a high temperature on the luminescent properties of oxygen-deficient corundum was studied. Efficient photoconversion, F- => F+-centres, which leads to appearance of the 3.76 eV F+-centre emission in the main dosimetric TL peak and the 5.91 eV band in luminescence excitation spectra of this centre, was found. Correlation between the integral intensity of the TL peak in the 3.76 eV emission band and the intensity of the 5.91 eV excitation band was established. Probable mechanisms of the thermostimulated photoconversion and TL in the F+-centre emission band are discussed.

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