Transfer of metal ions in the soil-root interface: influence of copper(II) on the stability of the fibrils

A network of Ca-polygalacturonate arranged in fibrils similar to those of plant roots (Gessa C. and Deiana S., (1990); C.Gessa and Deiana S., (1990)) constitutes a very useful model far the study of the ionic transfer both in the soil-root interface and in the apoplast. Due to the fact that important properties of the network, such as the hydration degree and the absorption phenomena, vary dramatically with the reticulating ion (Gessa C. and Deiana S., (1989)), this note reports on the influence of the metal ions on the fibrillar structure of the network and gives further information about the transfer of the metal ions to the roots

Effects of Al substitution on goethite formation

Goethites containing up to 32.7 mole % Al were synthesized and characterized through diffractometry, spectrometry, DSC and chemical techniques. Results indicate that crystal growth was favoured or hindered depending on the percentage of aluminum incorporated into the structure. Goethites to which 5-10 mole % Al were initially added crystallized best, as shown by the highest crystallite dimensions calculated from X-ray and Mössbauer analyses, and by the lowest surface areas values. Over such substitution degree goethite crystallization was hindered and for sample synthesized in presence of 40 mole % Al the separation of a discrete amount of gibbsite and bayerite occurred. Both crystallinity and Al-substitution degree influenced the goethite dehydroxylation endothermic peak temperature playing a competitive action in the peak shift. In fact, the increase in the thermal stability induced by the presence of Al3+ ions into the structure was counteracted by the decrease due to the particle size reduction. The stabilizing effect of aluminum was confirmed by the oxalate treatment which removed from the Al-free sample a Fe amount higher than that from the sample containing about 20 mole % Al, although both had similar crystallinity

Transfer of metal ions at the soil-root interface: role of VO²⁺ on Fe³⁺ mobilization from a Fe(III)-network

This note reports the role of VO(IV) on Fe(III) mobilization from a Fe(III)-polygalacturonate network. The effect of the reaction on the physical properties of the system is also considered

Role of the polygalacturonate network on the iron (III) reduction by caffeic acid

This communication reports the role of polygalacturonate network on the Fe(III) reduction by caffeic acid. The effect of phosphate ions on the redox reaction is also considered

Sediment features and heavy metal levels in four areas of Sardinia devoted to bivalve culture = Caratteristiche dei sedimenti e livelli di metalli pesanti in quattro aree della Sardegna idonee all’allevamento dei bivalvi

Sediment characteristics and Cd, Cu, Mn, Pb and Zn concentrations were assessed in the lagoons of Marceddì, Calich and Porto Pozzo, and in the inner part of the Gulf of Olbia. Sediment of the zones examined were quite similar, except for the Calich lagoon that showed the higher content of total organic carbon. High values of Cd, Pb and Zn were detected in the sediments of the Marceddì lagoon, while remarkable levels of Cu and Mn were found in the Calich lagoon and in the Gulf of Olbia

Influenza dei metodi di estrazione e di purificazione sul dosaggio in HPLC degli idrossifenoli

Four different extraction methods were compard, in oder to optimize the HPLC separation and quantitation of hydroxyphenols in «Thymus capitatus». One method was not suitable for HPLC ansly,is, whereas the others partially destroyed the hydroxyphenols extracted from the plant. The Charpentier-Cowles me thod was, found the most effective allowing to analyse, in spite of the losses, most of the free phenolic acids and of those bounded extractable in hot acidic medium but not in ethanol. For the phenolics in free form a method whith recoverier greater than those obtained with Hagerman Nicholson and Horvat-Senter methods was developed

Role of the caffeic acid oxidation products on the iron mobilization at the soil-root interface

Previous results show that the reduction of Fe(III) by caffeiic acid (CAF) is strongly influenced by the pH of the reaction medium (DEIANA et al., 1995). In particular, it has been found that al pH > 3.8 the reducing activity of CAF towards the Fe(III) ions in solution is low, but it increases when Fe(III) is complexed as Fe(III)-polygalacturonate. The mobilization of the Fe(II) ions, which form upon the Fe(III) reduction, has been shown to depend mainly on the nature of the Fe(III)-polygalacturonate complexes (DEIANA et al., 1994a). In particular, it bas been observed a high redox activity of CAF towards Fe(III) when the metal ion is coordinated by the carboxilic groups of the macromolecule. The Fe(III) reduction has been found to decrease when an oxydrilic group was inserted in the Fe(III) coordination sphere. The Fe(II) produced partly diffuses into the external solution and partly is still strongly held by the polysaccharidic matrix. The oxidation of CAF by Fe(III) gives rise to the formation of products (OP) with different polymerization degree, some of which are similar to those found in natural systems (DEIANA et al., 1994b). In order to determine the role of these products in the Fe(III) reduction as well as in the mobilization of the Fe(II) produced it was set up an electrochemical method to synthetize these products (DEIANA et al., 1994b). Here are reported some results about the interaction which establish between the CAF oxidation products and iron in both oxidized and reduced form

Electrochemical properties of Fe and Al hydroxides as affected by different supporting electrolytes

Potentiometric titration curves of Fe and Al hydroxides, carried out in presence of different electrolytes (KCI, Kbr, KI, KNO3, KCIO4) were elaborated by the Stern theory through a computered program. The zero points of charge (zpc), calculated from the intersection point of the titration curves at different ionic strenght, varied from pH 7.10 to pH 7.65 for Fe hydroxides and from pH 9.10 pH 9.45 for Al hydroxi des. For Fe compounds, a good match was found between the experimental values and those calculated by the Stern model. High deviations were observed only with KCIO4, in whose presence a lowering of the zpc was registered. Also in Al hydroxides the proposed model was not reliable below zpc, indicating that the surface interac tions are somewhat involved in specific adsorption phenomena

Plasma clusterin and lipid profile: a link with aging and cardiovascular diseases in a population with a consistent number of centenarians

The role of Clusterin in attenuation of inflammation and reverse cholesterol transfer makes this molecule a potential candidate as a marker for cancer, cardiovascular disease, diabetes mellitus, and metabolic syndrome. In elderly subjects cardiovascular diseases represent the primary cause of death and different clinical studies have shown a positive correlation of these diseases with changes in the lipid pattern. This work aimed at evaluating the relationship between circulating clusterin and the biochemical parameters that characterize the lipid profile of a Sardinian population divided into five age groups including centenarians; the high frequency in Sardinia of these long-lived individuals gave us the opportunity to extend the range of the age groups to be analyzed to older ages and to better evaluate the changes in the lipid balance during ageing and its relationship with clusterin concentration in plasma. Our results showed that Clusterin concentration values of the youngest group were more similar with the centenarian’s group compared to the other age groups, and a positive correlation arises with LDL. Furthermore given the high prevalence of cardiovascular diseases in the population examined and the association of Clusterin with these pathologies we evaluated Clusterin concentration variation in two groups with or without cardiovascular diseases. In presence of cardiovascular disease, Clusterin is significantly related to the most atherogenic components of lipid profile (total cholesterol and LDL), especially in women, suggesting its potential role in modulating cardiovascular metabolic risk factors

Solar Observations with Single-Dish INAF Radio Telescopes: Continuum Imaging in the 18 - 26 GHz Range

We present a new solar radio imaging system implemented through the upgrade of the large single-dish telescopes of the Italian National Institute for Astrophysics (INAF), not originally conceived for solar observations