An existence theorem for some nonlinear quasi-elliptic equations

Sunto In questo lavoro si prova l'esistenza di una soluzione periodica di classe C dell'equazione quasiellittica totalmente non lineare: v + F(D _x ⁴ v, Dsky/4v)=f.

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Lavoro eseguito nell'ambito del G.N.A.F.A. del C.N.R.     

The role of ethanol-water solvent mixtures in N719 sensitization of electrodeposited ZnO nanorods

Water plays an important role in N719 sensitization of ZnO films for application as photoanodes in DSC devices. The role of water content in ethanolic N719 sensitization solutions was examined resorting to N719-solvent interaction studies based on Kamlet-Taft solvatochromic parameters. Results show that as the water content increases, solvent’s HBA ability decreases, hindering dye aggregation in solution and increasing the fraction of dye carboxylic groups available for anchorage onto the charged ZnO surface. The impact of dye-dye-solvent equilibria in solution on ZnO nanorod films sensitization and device behavior was evaluated. Devices assembled with films sensitized in N719 solutions containing equal parts of ethanol and water showed a twofold increase in short-circuit current densities when compared to those sensitized in ethanol only, despite exhibiting significantly less stained films. Data indicate that the presence of water in the sensitization solution reduces the amount of dye aggregates in solution and on the ZnO surface.     

Diuretic activity of Lophophytum leandri

A bioassay-oriented study was carried-out in order to validate the traditional uses of Lophophytum leandri, a parasitic plant used as a diuretic in traditional medical practices of Argentina. Four known flavonoids have been isolated from the active fraction. Quercetin-3-O-beta-D-glucopyranoside was identified as the active principle of the fraction. However, the diuretic activity of the extract and of the most active fraction had greater activity than that of the pure isolated compounds.     

Solution enthalpies of 1-bromoadamantane in monoalcohols at 298.15 K

Solution enthalpies of 1-bromoadamantane in 14 monoalcohols were measured at 298.15 K. Comparison with the solution enthalpies of 2-bromo-2-methylpropane was performed. The obtained data were discussed in terms of the effect of solute's size and solvent's structure.     

Evaluation of mobile phase, ion pairing, and temperature influence on an HILIC-MS/MS method for L-arginine and its dimethylated derivatives detection

Asymmetric N(G),-N(G)-dimethylarginine (ADMA) increases in diseases such as renal failure, diabetes mellitus, and hypercholesterolemia. The feasibility and utility of a hydrophilic interaction chromatography (HILIC) method for the separation of free L-arginine (Arg), ADMA, and symmetric N(G),-N(G')-dimethylarginine (SDMA) on a typical silica column were explored and the impact of some experimental parameters on the chromatographic behavior of these analytes was investigated. The effect of water and TFA content in mobile phase and of column temperature was investigated during the development of a fast and simple HILIC-MS/MS method that might be suitable for the quantification of free Arg, ADMA, and SDMA in plasma for routine analysis. Our results show that a good compromise between efficiency and peak shape with acceptable retention and total chromatographic run time is achieved using an ACN/water (90:10) mobile phase with TFA% as additive ranging from 0.015 to 0.025% and column temperature ranging from 25 to 30 degrees C.     

Characterisation of the essential oil of Nepeta glomerata Montbret et Aucher ex Bentham from Lebanon and its biological activities

The essential oil of Nepeta glomerata from Lebanon was studied by means of GC and GC/MS analysis; 70 compounds were identified. The oil was constituted mainly by monoterpenes and the most abundant components were α-pinene, spathulenol and carvacrol. Nepeta glomerata oil showed antibacterial activity, particularly towards Gram-positive bacteria, and also inhibited LPS-induced NO production in macrophage cell line RAW 264.7, with an IC(50) value of 78.1 μg mL(-1). Furthermore, an in?vitro cytotoxic assay showed that the oil was more active on a renal adenocarcinoma cell line (48% of inhibition of proliferation at 100 μg mL(-1)) in comparison to an amelanotic melanoma.     

A remark on uniqueness of weak solutions for some classes of parabolic problems

We prove some uniqueness results for weak solutions to some classes of nonlinear parabolic equations with homogeneous Cauchy-Dirichlet boundary condition. Precisely we consider operators with a first order term or operators which have just principal part depending on \(u\).     

Multivariate analysis of nutritional information of foodstuff of plant origin for the selection of representative matrices for the analysis of pesticide residues

Testing safety of foodstuffs of plant origin involves the analysis of hundreds of pesticide residues. This control is only cost-effective through the use of methods validated for the analysis of many thousands of analyte/matrix combinations. Several documents propose representative matrices of groups of matrices from which the validity of the analytical method can be extrapolated to the represented matrices after summarised experimental check of within group method performance homogeneity. Those groups are based on an evolved expert consensus based on the empirical knowledge on the current analytical procedures; they are not exhaustive, they are not objectively defined and they propose a large list of representative matrices which makes their application difficult. This work proposes grouping 240 matrices, based on the nutritional composition pattern equivalence of the analytical portion right after hydration and before solvent extraction, aiming at defining groups that observe method performance homogeneity. This grouping was based on the combined outcome of three multivariate tools, namely: Principal Component Analysis, Hierarchical Cluster Analysis and K-Mean Cluster Analysis. These tools allowed the selection of eight groups for which representative matrices with average characteristics and objective criteria to test inclusion of new matrices were established. The proposed matrices groups are homogeneous to nutritional data not considered in their definition but correlated with the studied multivariate nutritional pattern. The developed grouping that must be checked with experimental test before use was tested against small deviations in food composition and for the integration of new matrices.