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The fertilization management of the rice crop in Piedmont was analyzed at a regional scale, and the agronomic and environmental sustainability of the actual fertilization strategy of rice was evaluated through the analysis of its effect on the soils and waters quality.The fertilization management of the rice crop in Piedmont was analyzed at a regional scale, and the agronomic and environmental sustainability of the actual fertilization strategy of rice was evaluated through the analysis of its effect on the soils and waters quality.

The influence of the total downstream pressure on the pervaporation flux of a pure compound through a dense polymer membrane has been the subject to controversial debates recently. Experimental arguments in favor of either the solution−diffusion model or the newly proposed pore-flow model are alternatively reported on different systems. To critically reexamine this debate, an experimental study under controlled downstream conditions has been performed for pure methanol and pure 2-propanol pervaporation through a poly(dimethylsiloxane) film, the latter having been previously reported to follow pore-flow model predictions. It is shown that a rational analysis of the effects of the downstream pressure on the results can be achieved according to the classical solution−diffusion model, provided that the influence of air leaks in the installation is properly taken into account. Based on this observation, the implications of an inert gas contribution, generally speaking, on pervaporation operation are discussed.

Summary To prepare dextran-linked benzene polycarboxylic acids which are stable in-vivo, the acids were allowed to react with aminated dextrans in water, in the presence of a water-soluble carbodiimide. Under these conditions, ester linkages are formed preferentially to amide ones, probably because of the formation of intramolecular cyclic anhydrides promoted by the carbodiimide. Thus, with benzoic acid, esterification also took place, but to a much lesser extent.

A ligand-exchange chromatography procedure for the separation of cephalosporin C from an artificial mixture is described. Three new sorbents were synthesized by immobilizing the ligands ε-L-lysine, glycyl-ε-L-lysine and diglycyl-ε-L-lysine on a polystyrene matrix(SX 1 Bio-Rad). These resins were loaded with Cu(II) as a complexing agent. A good resolution of cephalosporin C was achieved only using the ε-L-lysine resin complexed with copper. Models of copper complexes involved are proposed, for the chromatographic separation of cephalosporin C.

The prediction of equilibrium volume fractions of solvents mixtures in a polymer network is of utmost importance for processes dealing with polymeric materials (e.g. chromatographic and membrane processes). Up to now, few studies have studied the ability of existing theories to predict experimental multicomponent sorption data in polymers; this work intends to achieve that purpose on model liquid mixtures in contact with silicone rubber (polydimethylsiloxane). The equilibrium volume fractions of three liquid mixtures (chloroform/toluene; ethanol/toluene; ethanol/2-butanol) in crosslinked PDMS samples have been determined experimentally at 40°C. Results are compared to predictions by the Flory-Huggins theory applied to ternary mixtures (one polymer and two liquids) with constant interaction parameters and negligible elastic contribution. Solvent/polymer interaction parameters have been determined by swelling the crosslinked samples in pure liquids, while liquid/liquid interaction parameters have been estimated from liquid/vapor equilibrium data. It is shown that the Flory-Huggins theory offers good predictions in the case of good (chloroform, toluene) and fair (2-butanol) PDMS solvents, while significant discrepancies are obtained with a non solvent (ethanol). Implications in ternary diagrams simulation and possible prediction improvements, based on non constant interaction parameters, are discussed.

The present study deals with the fixation of benzene polycarboxylates such as benzene hexacarboxylate (BHC) or benzene tetracarboxylate (BTC) onto dextran, with the aim of obtaining polyanionic polymers capable of decreasing the oxygen affinity of Hb by interacting with its phosphate binding site. The synthesis was carried out according to several reaction schemes. The polyanionic polymers presented the strongest effector properties, when the polyanionic molecule (BHC or BTC) were directly fixed onto the hydroxyl functions of dextran in the presence of a carbodümide or by means of the benzene tetracarboxylic anhydride. The introduction of a spacer arm between the polymer and the polyanionic molecule led to the formation of crosslinking between chains of dextran. Among the synthesized polymers those which possess effector properties similar to those of 2,3-diphosphoglycerate (2,3-DPG) were bound onto oxyHb. The resulting covalent conjugates exhibited a low oxygen affinity and a molecular size quite fitted to a potential use as blood substitutes.

Mealybugs (Hemiptera: Pseudococcidae) represent a serious threat for viticulture as vectors of phloem-restricted viruses associated with the grapevine rugose wood and leafroll diseases. Heliococcus bohemicus (Sˇulc) is known to be involved in the spread of these two viral diseases, being a vector of the Grapevine virus A (GVA) and the Grapevine leafroll-associated virus 1 and 3 (GLRaV-1 and GLRaV-3). This study investigated the acquisition and transmission efficiency of H. bohemicus fed on mixed-infected plants. Nymphs were field-collected onto GVA, GLRaV-1, and GLRaV-3 multiple-infected grapevines in two vineyards in North-Western Italy, and were used in transmission experiments under controlled conditions. Even if most of the collected nymphs were positive to at least one virus, transmission occurred only to a low number of test grapevines. The transmission frequency of GLRaV-3 was the highest, whereas GVA was transmitted to few test plants. The transmission of multiple viruses occurred at low rates, and nymphs that acquired all the three viruses then failed to transmit them together. Statistical analyses showed that the three viruses were independently acquired and transmitted by H. bohemicus and neither synergistic nor antagonistic interactions occurred among them. GVA and GLRaVs transmission efficiencies by H. bohemicus were lower than those reported for other mealybug vectors. This finding is consistent with the slow spread of leafroll and rugose wood diseases observed in Northern Italy, where H. bohemicus is the predominant vector species.

Abstract  Copyright © 2004 S. Karger AG, Basel

We present an innovative compact dual-modality detector, which integrates an ultrasound probe with a scintigrafic γ-camera for molecular imaging in medicine, in order to get both morphological and functional information in a single three-dimensional image. The scintigraphic detector consists of a array of a multi-anode PMT Hamamatsu H8500-Mod8 and a 4.0 mm thick continuous LaBr3(Ce) crystal equipped with four segment slant-hole collimators for single photon imaging (SPET). The collimator permits to recover the depth of a lesion by rotating around its vertical axis (z) without the need of rotating the camera around the investigated object. This detector can take advantage from being positioned close to the object and overcome the intrinsic limitations in spatial resolution arising from the geometry of SPET/CT gantry. The aim of this work is to describe preliminary phantom analysis and to provide a 3D US/SPET image. [ABSTRACT FROM AUTHOR]

The development of the molecular imaging technique based on radiopharmaceuticals is requiring sophisticated devices with sub-millimeter spatial resolution and high detection efficiency. Recently, in the field of scintillation gamma camera, it has been demonstrated that continuous crystals may improve spatial resolution with respect to the use of scintillation arrays. In this work we propose a new algorithm that improves spatial resolution. It calculates the position from a single scintillation event by squaring the charge collected on a multi-anodes photomultiplier tube (MA-PMT). It is able to remove the position linearity distortion due to the light reflections and the truncations at the crystal edge. We present measurements from a compact gamma camera based on a 51 mm × 51 mm × 4.0 mm LaBr3:Ce continuous scintillation crystal, coupled to a MA-PMT Hamamatsu H8500. The results show a strong improvement in spatial resolution and confirm the high potential in using of LaBr continuous crystal for molecular imaging applications. [Copyright &y& Elsevier]