Three types of Ti O2 nanostructures were synthesized via a facile hydrolysis method at195 °C. Effects of the preparation method and doping with N and F on the crystal structure and photocatalytic performance of Ti O2 were investigated. The nanomaterials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller porosimetry, ultraviolet–visible diffuse reflectance spectroscopy and fluorescent emission spectra. Their photo-catalytic activity was examined by the photodegradation of methylene blue in aqueous solution under both ultra-violet and visible light irradiation. The results show that nitrogen and fluorine co-doped anatase Ti O2 had the characteristics of a smaller crystalline size, broader light absorption spectrum and lower charge recombination than pure Ti O2. Most importantly, more efficient photocatalytic activity under both ultra-violet and visible light was observed. The obtained N–F-Ti O2 nanomaterial shows considerable potential for water treatment under sunlight irradiation.
Photolysis of 4-acetyl-4-ethoxyformylcyclohexanone, 4-acetyl-4-phenylcyclohexanoneand 1-acetyl-1-phenylcyclohexane in deuteriochloroform using a high pressure Hg-Xe lamp showedunusual polarizations. The results are explained by the formation of a singlet exciplex of the ketonewith deuteriochloroform and the photoaddition of deuteriochloroform to the ketone.
With the onset of downsized and highly-boosted engines,engine designers are encountering a new combustion phenomenon,called low-speed pre-ignition(LSPI) or superknock,which occurs when the engine operates under a low-speed,high-load conditions.LSPI events cause large spikes in cylinder pressure that can easily exceed the design limits of the engine.Therefore,it is important for the automotive industry to understand how LSPI events occur and develop a solution that can either eliminate it or detect and mitigate its effects.This paper summarizes the existing work that has been conducted on the subject of LSPI.Much of the research work presented hypothesizes that physical and chemical interactions and accumulation of fuels and lubricants in the piston top land crevice volume affect the frequency of LPSI events.Therefore,it may be possible to formulate fuels and lubricants that can mitigate or eliminate the occurrence of LPSI.
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