Use of different spectroscopic techniques in the analysis of Roman age wall paintings.

In this paper the analysis of samples of Roman age wall paintings coming from: Pordenone, Vicenza and Verona is carried out by using three different techniques: energy dispersive x-rays spectroscopy (EDS), x-rays fluorescence (XRF) and proton induced x-rays emission (PIXE). The features of the three spectroscopic techniques in the analysis of samples of archaeological interest are discussed. The studied pigments were: cinnabar, yellow ochre, green earth, Egyptian blue and carbon black.

Radicalization of lignocellulosic fibers, related structural and morphological changes.

The radicalization of unbleached lignocellulosic fibers obtained from thermomechanical (TMP) and chemothermomechanical (CTMP) pulps was performed in heterogeneous phase by reaction with dioxygen in the presence of N,N'-ethylenebis(salicylideneiminato)cobalt(II), [Co(salen)], as catalyst. Phenoxy cobalt radicals immobilized in fibers were observed by electron paramagnetic resonance (EPR) spectroscopy; their amount depends on the fiber swelling induced by reaction medium. The absolute concentration of such radicals in fibers, about 10(16) spin/g, reaches values 10 times higher than that of phenoxy radicals formed in similar oxidative reactions catalyzed by laccase. The generation of phenoxy cobalt radicals in fibers was related to structural changes of lignin units, detected by mono- and bidimensional nuclear magnetic resonance ((13)C NMR and 2D-HSQC) investigations, and to morphological modifications in fibers observed by scanning electron microscopy (SEM).

Effects of copper on Sambucus nigra L. seedlings studied by electron paramagnetic resonance and atomic absorption spectroscopies.

We present in this work preliminary results on the translocation of copper, manganese and iron from soil to leaves of Sambucus nigra L. seedlings in the presence of increasing copper concentrations in the growth medium. The use of electron spin resonance spectroscopy and the comparison with atomic absorption spectroscopy is not presently common in the study of metal absorption in plants. This approach gave promising results both on the detection of some metal ions, as well as of radical species related to the presence of Cu2+ in plant tissues. Copper was found to act synergistically in manganese uptake.

Evaluation and further development of the activated sludge respiration inhibition test.

The activated sludge respiration inhibition test is an important bacterial test system for the determination of bacterial toxicity of chemical compounds. The exposure period recommended by OECD 209 and ISO 8192 protocols is 30 and 180 min. A modified version of the test was developed which allowed a prolonged incubation period of 27 h to enhance the possibilities of the test system. The test system with the prolonged incubation time was evaluated by the recommended reference compound 3.5-dichlorophenol and showed an EC50 of 6.3 mgl(-1) with a coefficient of variation of 12.7%. Furthermore, the use of an open test system was evaluated showing a comparable toxicity but a higher coefficient of variation than the closed test system. A storage of activated sludge for several days accompanied by a daily feed with OECD nutrient solution should be avoided, for it can cause a decreased sensitivity of the inoculum. Different statistical fit procedures were tested indicating that Weibull fit procedures were superior for extended data sets covering a wide range of concentrations whereas Gamma and Probit fits were appropriate for smaller data sets mainly restricted to the linear part of the dose response curve.

Substituted aniline interaction with submitochondrial particles and quantitative structure-activity relationships.

The toxic effects of eighteen substituted anilines were determined by means of a short-term in vitro assay, using submitochondrial particles (SMP) as biosensors. The assay allows for the quantification of the effects of toxicants that act specifically on mitochondrial respiratory functions, like uncouplers and inhibitors, or non-specifically, by disturbing the structure and functioning of the inner mitochondrial membrane. The obtained EC(50) values range from 72.5 to 1910 micromol/l. The type and position of the substituents are of fundamental importance in determining the toxic potency. In general, the presence of electron-withdrawing substituents produces higher toxic effects, whereas electron-donating groups seem to reduce the toxicity. Quantitative structure-activity relationships (QSAR) showed that toxicity values were correlated with the Hammett sigma constant and with hydrogen bonding capacity descriptors, such as E(LUMO), E(HOMO) and Q(+). The results indicate that toxicity increases with increasing the hydrogen bonding donor capacity of the NH(2) group and support the hypothesis of a mechanism of action based on hydrogen bonding formation between the amino group of anilines and polar groups at the membrane/water interface. Such an interaction would cause a derangement of the membrane structure and, as a consequence, a disturbance of its functioning.