The adsorption and photodecomposition of seven kinds of amino acids on a TiO2 surface were investigated by zeta potential measurements and 1H NMR spectroscopy in TiO2 aqueous suspension systems. The decomposition rates increased in the order of Phe < Ala < Asp < Trp < Asn < His < Ser. For Phe, Trp, Asn, His, and Ser, the isoelectric point (IEP) of TiO2 shifted to a lower pH with increasing decomposition rates upon adsorption on TiO2, suggesting that the effective adsorption and photocatalytic sites for these amino acids should be the basic terminal OH on the solid surface. Since the amino acids that decomposed faster than the others contain -OH (Ser), -NH (Trp, His), or -NH2 (Asn) in their side chain, they are considered to interact with the basic terminal OH groups more preferably by the side chain and are vulnerable to photocatalytic oxidation. On the other hand, Ala interacts with the acidic bridged OH on TiO2 to cause an IEP shift to a higher pH. The correlation of the surface hydroxyl groups with the photocatalysis of amino acids was verified by the use of calcined TiO2 without surface hydroxyl groups.

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Abstract-Noise in PLC is of relatively complex structure of which the most important component is the asynchronous impulsive noise. Based on measurements realized in an industrial zone, this paper shows the heavy tail phenomenon observed in experimental measures. Consequently, the alpha stable model is the most natural to be used in describing the statistics of PLC impulsive noise in industrial zones. Furthermore, the inter-arrival time is of Pareto distribution while the duration of impulses follows a mixed exponential distribution. All parameters of the alpha stable model as well as the Pareto parameters and the mixed exponents are statistically estimated. The variation of these parameters with time is also discussed.Index Terms-Power line communication, impulsive noise, measurement and characterization.

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