Simulation of ozone depletion using ambient irradiance supplemented with UV lamps

In studies of the biological effects of UV radiation, ozone depletion can be mimicked by performing the study under ambient conditions and adding radiation with UV-B lamps. We evaluated this methodology at three different locations along a latitudinal gradient: Rimouski (Canada), Ubatuba (Brazil) and Ushuaia (Argentina). Experiments of the effect of potential ozone depletion on marine ecosystems were carried out in large outdoor enclosures (mesocosms). In all locations we simulated irradiances corresponding to 60% ozone depletion, which may produce a 130-1900% increase in 305 nm irradiance at noon, depending on site and season. Supplementation with a fixed percentage of ambient irradiance provides a better simulation of irradiance increase due to ozone depletion than supplementation with a fixed irradiance value, particularly near sunrise and sunset or under cloudy skies. Calculations performed for Ushuaia showed that, on very cloudy days, supplementation by the square-wave method may produce unrealistic irradiances. Differences between the spectra of the calculated supplementing irradiance and the lamp for a given site and date will be a function of the time of day and may become more or less pronounced according to the biological weighting function of the effect under study.     

A spectral quadrilateral multidomain penalty method model for high Reynolds number incompressible stratified flows

A two‐dimensional quadrilateral spectral multidomain penalty method (SMPM) model has been developed for the simulation of high Reynolds number incompressible stratified flows. The implementation of higher‐order quadrilateral subdomains renders this model a nontrivial extension of a one‐dimensional subdomain SMPM model built for the simulation of the same type of flows in vertically nonperiodic domains (Diamessis et al., J. Comp. Phys, 202 :298‐322, 2005). The nontrivial aspects of this extension consist of the implementation of subdomain corners, the penalty formulation of the pressure Poisson equation (PPE), and, most importantly, the treatment of specific challenges that arise in the iterative solution of the SMPM‐discretized PPE. The two primary challenges within the framework of the iterative solution of the PPE are its regularization to ensure the consistency of the associated linear system of equations and the design of an appropriate two‐level preconditioner. A qualitative and quantitative assessment of the accuracy, efficiency, and stability of the quadrilateral SMPM solver is provided through its application to the standard benchmarks of the Taylor vortex, lid‐driven cavity, and double shear layer. The capacity of the flow solver for the study of environmental stratified flow processes is shown through the simulation of long‐distance propagation of an internal solitary wave of depression in a manner that is free of numerical dispersion and dissipation. The methods and results presented in this paper make it a point of reference for future studies oriented toward the reliable application of the quadrilateral SMPM model to more complex environmental stratified flow process studies. Copyright © 2014 John Wiley & Sons, Ltd.     

Raman Spectra of Alkali and Alkaline Earth Metal Salts of Inosine 5′-Monophosphoric Acid

Crystalline Li(I), Na(I), K(I), Mg(II), Ca(II), Sr(II), Ba(II) and Cd(II) salts of inosine 5′-monophosphoric acid, H₂(IMP), were obtained and characterized by Raman spectroscopy. Splitting of the imidazolic 1480 cm⁻¹ band was observed for the N(7)-bound Ca(IMP)·6H₂O, Ba(IMP)·6H₂O, Sr(IMP)·6H₂O and Cd(IMP)·4H₂O compounds. The Li(I), Mg(II), Ca(II) and Cd(II) ions bind directly to the phosphate group, and no direct coordination involving the carbonyl C(6)O group was observed in the compounds reported here. Some Raman spectral features in the 750–700 cm⁻¹ range seem to reflect the nucleoside structure of the inosine moiety