Field Study on Mobility and Persistence of Linuron and Monolinuron in Agricultural Soil

Abstract

A field site equipped with suction cup lysimeters was installed at Treviglio (BG) to assess the migration capacity of the herbicides linuron and monolinuron from topsoil to groundwater and to verify the appearance of their relevant transformation products in soil and water samples. A constant hydraulic head was applied in order to develop water saturation conditions in the upper layers. KCl was used as a tracer to evaluate water infiltration velocity through the vertical soil profile. The constant hydraulic head accelerated infiltration rates, while herbicide concentrations reached maximum contamination because soil adsorption capacity was underdeveloped. The results indicated two main processes of pesticide transport: firstly transport due mainly to water infiltration through macropores; secondly the transport driven by matrix flow. Linuron was found to be the most mobile herbicide, while chloroanilines were found to be the major transformation products of the herbicides considered.     

Adaptive Interpolation by Scaled Multiquadrics

We present an adaptive method to extract shape-preserving information from a univariate data sample. The behavior of the signal is obtained by interpolating at adaptively selected few data points by a linear combination of multiquadrics with variable scaling parameters. On the theoretical side, we give a sufficient condition for existence of the scaled multiquadric interpolant. On the practical side, we give various examples to show the applicability of the method.     

New Class of Chiral Diphosphine Ligands for Highly Efficient Transition Metal-Catalyzed Stereoselective Reactions: The Bis(diphenylphosphino) Five-membered Biheteroaryls

The synthesis and application of three examples of a new class of chiral (C(2)) atropisomeric diphosphines characterized by two interconnected five-membered heteroaromatic rings, with hindered rotation around the interanular bond, are described. Optically pure (+)- and (-)-2,2'-bis(diphenylphosphino)-4,4',6,6'-tetramethyl-3,3'-bibenzo[b]thiophene (tetraMe-bitianp) (1a) and the parent unsubstituted system (+)- and (-)-bitianp (1b) were synthesized. They were found to be optically stable at 100 degrees C and were successfully employed as ligands in the Ru(II)-catalyzed hydrogenation of alpha- and beta-oxo esters to the corresponding alpha- and beta-hydroxy esters and in the hydrogenation of olefinic substrates. The optical and chemical yields were comparable with those reported for the same Ru(II)-binap-catalyzed reactions carried out under the same experimental conditions. The 2,2'-bis(diphenylphosphino)-3,3'-bibenzo[b]furan (1c), the oxygenated analogue of bitianp, was found to be configurationally unstable at room temperature. Complete structural X-ray elucidation of the Pd complexes of 1a-c is reported. The advantages of these biheteroaromatic ligands over the classical biaryl systems are discussed.     

Fatty acids determination in Bronte pistachios by gas chromatographic method

A gas chromatographic with flame ionization detector (GC-MS FID) method for the identification and quantification of fatty acids based on the extraction of lipids and derivatisation of free acids to form methyl esters was developed and validated. The proposed method was evaluated to a number of standard FAs, and Bronte pistachios samples were used for that purpose and to demonstrate the applicability of the proposed method. In this regard, repeatability, mean and standard deviation of the analytical procedure were calculated. The results obtained have demonstrated oleic acid as the main component of Bronte pistachios (72.2%) followed by linoleic acid (13.4%) and showed some differences in composition with respect to Tunisian, Turkish and Iranian pistachios.     

Morse Novikov theory and cohomology with forward supports

We present a new approach to Morse and Novikov theories, based on the deRham Federer theory of currents, using the finite volume flow technique of Harvey and Lawson [HL]. In the Morse case, we construct a noncompact analogue of the Morse complex, relating a Morse function to the cohomology with compact forward supports of the manifold. This complex is then used in Novikov theory, to obtain a geometric realization of the Novikov Complex as a complex of currents and a new characterization of Novikov Homology as cohomology with compact forward supports. Two natural ``backward-forward' dualities are also established: a Lambda duality over the Novikov Ring and a Topological Vector Space duality over the reals.     

Oxygen migration in A2B2O7 pyrochlores

Atomic scale computer simulation has been used to predict activation energies for oxygen migration. In total, 54 compounds with the A₂B₂O₇ pyrochlore structure were simulated. In each case, oxygen migration was assumed to proceed via an oxygen vacancy mechanism with oxygen ions hopping between 48f sites. For some compounds the unoccupied 8a interstitial position played an important role in the migration mechanism. The results were analyzed using a contour map of activation energy versus A cation radius along the ordinate and B cation radius along the abscissa. This identified areas of similar cation radii, which exhibit lower activation energy. Results compare favourably with available experimental data.     

Kernel B-splines on general lattices

The aim of the paper is to provide a computationally effective way to construct stable bases on general non-degenerate lattices. In particular, we define new stable bases on hexagonal lattices and we give some numerical examples which show their usefulness in applications.     

Technetium-99m nitride radiopharmaceuticals

Following the introduction of an efficient method for the preparation of technetium-99m complexes containing a terminal Tc-N multiple bond, under conditions suitable for nuclear medicine applications, new radiopharmaceuticals for heart and brain imaging have been discovered. These compounds belong to the class of bi-substituted, square-pyramidal nitride TcV complexes with dithiocarbamate ligands, and are the first examples of radiopharmaceuticals of this type exhibiting interesting biological properties. The peculiar chemical characteristics of the Tc-N core can also be conveniently utilized for the design of radiopharmaceuticals incorporating bioactive peptides and having definite structural features.