Effective UV photolytic decomposition of organic compounds with a low-pressure mercury lamp as pretreatment for voltammetric analysis of trace metals

The effectivity of UV irradiation with low and high pressure mercury (L-Hg and H-Hg) lamps on the decomposition of organic compounds in aqueous solutions, as pretreatment for the voltammetric determination of trace metals, is compared. The photolytic decomposition with the L-Hg lamp was much faster than with the H-Hg lamp. The higher efficiency of the L-Hg lamp is caused by its greater light intensity at short wavelengths. Interferences of organic compounds on the voltammetric determination of nickel and indium were eliminated successfully by 90 min irradiation with the L-Hg lamp. Humic acid and organic interference with the voltammetric determination of nickel in natural river water were successfully eliminated. The decomposition using the L-Hg lamp can be carried out without added oxidizing reagents and at room temperature, thus eliminating loss of water samples by evaporation at higher temperature.     

Construction and decomposition of reflecting diffusions on Lipschitz domains with Hölder cusps

Summary. We consider a -dimensional Euclidean domain whose boundary is Lipschitz continuous but admits locally finite number of outward or inward H?lder cusp points. Using a method of Stampacchia and Moser for PDE, we first construct a conservative diffusion process on the Euclidean closure of possessing a strong Feller resolvent and associated with a second order uniformly elliptic differential operator of divergence form with measurable coefficients . The sample path of the constructed diffusion can be uniquely decomposed as a sum of a martingale additive functional and an additive functional locally of zero energy. The second additive functional will be proved to be of bounded variation with a Skorohod type expression whenever is weakly differentiable and the H?lder exponent at each outward cusp boundary point is greater than regardless the dimension . Received: 4 October 1995     

Stretched-exponential decay laws of general defect diffusion models

We calculate a correlation function of a dipole which flips upon contact with one of the defects making generally non-Gaussian diffusions. Other than the memory effect in the fractal random walk model, the non-Gaussian property can be an origin of the stretched-exponential law of the correlation function.     

Intrinsic ultracontractivity and small perturbation for one-dimensional generalized diffusion operators

We consider a one-dimensional generalized diffusion operator G on an open interval which is not necessarily bounded. We characterize [SP] (i.e., 1 is a small perturbation of the operator G) in terms of the classification of the boundary points from the view point of diffusion processes and give a sufficient condition for [IU] (i.e., the associated heat kernel is intrinsically ultracontractive).