Application of hybrid and moment methods to the measurement of moisture diffusion coefficients of building materials

This work proposes two simple dynamic methods that provide an accurate method for measurement of diffusion coefficients in building materials. Experimental measurements of moisture diffusion coefficients covered three commonly used building materials and they were carried out for a range of the relevant parameters, as temperature and relative humidity. The diffusion coefficients obtained by the two dynamic methods show a deviation comparatively to the steady-sate cup method; however, this variance is in accordance with the results presented in literature.     

Neutron activation analysis for identification of African mineral dust transport

A Gent stacked filter unit sampler was used to collect air particulate matter (APM) in separate coarse (PM_2.5–10) and fine (PM_2.5) size fractions, at a sub-urban site in Lisbon, Portugal. The sampling was done during the year 2001 and two daily samples were taken per week. The filters were analyzed for particulate mass by instrumental neutron activation analysis (INAA). The chemical analysis of APM levels and the study of the atmospheric dynamics by back-trajectories showed that most of the PM_2.5 and PM_2.5–10 peaks events were associated with air masses transport from the Saharan desert. High mineral load in ambient particulate matter levels were registered during the Saharan dust outbreaks. The accuracy of INAA to measure Fe, Sc and Sm was evaluated by NIST filter standards, revealing results with an agreement of ± 10%. This method constituted an important tool to identify these events.     

Joint assessment of responses of biomonitors to airborne nickel and vanadium through nuclear and non-nuclear techniques

This study deals with the influence of the exposure conditions on biological uptake, by looking into concentrations of Ni and V in lichen thalli and tree bark after continuous and discontinuous field trials at littoral sites impacted by anthropogenic emissions. Biomonitors were assessed by k ₀-INAA and AAS. Correlations at Sines are more apparent than at Viana or Lisboa. When data from all sites are pooled, V shows correlations for practically every situation while Ni shows none, which may indicate a dissimilar uptake mechanism for each element. At Sines, V/Ni ratios reach values that comply with emissions from oil-related industries.     

Discrete time Galerkin approximations to the nonlinear filtering solution

This paper concerns discrete time Galerkin approximations to the solution of the filtering problem for diffusions. Two families of schemes approximating the unnormalized conditional density, respectively, in an “average” and in a “pathwise” sense, are presented. L² error estimates are derived and it is shown that the rate of convergence is linear in the time increment or linear in the modulus of continuity of the sample path.     

Hetarylpyrazoles. IV. Synthesis and reactions of 1,5′-bipyrazoles

A number of 1, 5′-bipyrazoles were obtained from the condensation of pyrazol-5-ylhydrazine and 1, 3-dicarbonyl compounds. Electrophilic substitution reactions of these 1, 5′-bipyrazoles occur at the four position of the pyrazole ring.     

Near-forward Raman scattering intensity in ZnO

We have measured the Raman scattering intensities of the E₁ (TO) polariton mode in ZnO, a wurtzite type crystal, at room and liquid nitrogen temperatures. These results reveal a novel behavior in contrast to that observed for ZnSe. These results confirm earlier theoretical considerations.     

Predicting hydration free energies of neutral compounds by a parametrization of the polarizable continuum model

A parametrization of the polarizable continuum model (PCM) is presented having the experimental hydration free energies of 215 neutral molecules as target. The cavitation and dispersion contributions were based on the Tu?on-Silla-Pascual-Ahuir (Tu?on; et al. Chem. Phys. Lett. 1993, 203, 289) and Floris-Tomasi (Floris, F.; Tomasi, J. J. Comput. Chem. 1989, 10, 616) expressions, respectively. Both the polar and nonpolar contributions were evaluated on the same solvent-excluding molecular surface that used unscaled Bondi atomic radii. The parametrization was provided for the HF, Xalpha, LSDA, B3LYP, and mPW1PW91 methods at the 6-31G(d) basis set, and the results are in fair agreement with the experimental data. For the sake of comparison, the PCM(UAHF) and our parametrization (PCM2), both at HF level, have produced DeltaG(PCM(UAHF)) = aDeltaGexp (a = 1.02 +/- 0.02, r = 0.945, sd = 0.987, Ftest = 1778) and DeltaG(PCM2) = aDeltaGexp (a = 0.95 +/- 0.02, r = 0.952, sd = 0.843, Ftest = 2070), respectively. The mean absolute deviations from experimental data were 0.67 and 0.68 kcal/mol for PCM(UAHF) and PCM2, respectively.     

Charge-transfer complexation as a general phenomenon in the copigmentation of anthocyanins

Color intensification of anthocyanin solutions in the presence of natural polyphenols (copigmentation) is re-interpreted in terms of charge transfer from the copigment to the anthocyanin. Flavylium cations are shown to be excellent electron acceptors (E(red) approximately -0.3 V vs SCE). It is also demonstrated, for a large series of anthocyanin-copigment pairs, that the standard Gibbs free energy of complex formation decreases linearly with EA(Anthoc) - IP(Cop), the difference between the electron affinity of the anthocyanin, EA(Anthoc), and the ionization potential of the copigment, IP(Cop). Based on this correlation, copigmentation strengths of potential candidates for copigments can be predicted.