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  • Author or Editor: G. Angelini x
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Abstract  

Triazines are a class of molecules which have been found in meteorites such as Orgueil meteorite. Despite their poor resistance to UV radiation, these molecules survived millions of years inside a meteorite. The present work is dedicated to the examination of the radiation resistance of the simplest sym-triazine: 1,3,5-triazine. The crystals of this molecule have been irradiated with γ-radiation at 50 and 350 kGy and were studied by electronic absorption spectroscopy, liquid chromatography, FT-IR spectroscopy and differential scanning calorimetry (DSC). All the data suggest the relatively low stability of this molecule to high energy radiation. The resulting products from radiolysis are formamidine together with triazine dimers and oligomers. Other radiolysis products are H2, CH4, HCN and other gases.

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Abstract  

A series of substituted cinnamic acids labelled at the ring positions with deuterium or tritium has been easily obtained via the Doebner modification of Knoevenagel condensation reaction between labelled benzaldehyde derivatives and malonic acid in pyridine. The substituted benzaldehyde precursors were synthesized by isotope exchange method in deuterated or tritiated water at 80 °C in acidic medium. Ring-tritiated substituted cinnamic acids with specific activity ranging from 207 GBq /5.6 Ci/ mol–1 to 4366 GBq /118 Ci/ mol–1 was obtained using ca. 37 GBq /1 Ci/ of HTO.

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Abstract  

C60 fullerene was radiolyzed in toluene solution both in presence of air and in vacuum at four different radiation doses 12, 24, 36, 48 and 96 kGy. Clear evidences of the addition of benzyl radicals to the fullerene cage derive from FT-IR and C13-NMR spectra of the reaction product. In presence of air the interference of oxygen is evident in the FT-IR spectra and from the elemental analysis. A detailed analysis of the kinetics of the multiple addition of benzyl radicals to the fullerene cage was made spectrophotometrically with the determination of the addition rate constants at the each addition step and the average number of benzyl groups added to the fullerene cage as function of the radiation dose.

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Abstract  

Gelatin, the low molecular weight collagen derivative from porcine skin was transformed into a stable permanent hydrogel by γ-radiation. A series of samples with 3% gelatin solution in water were irradiated at doses of 12, 25, 50, 100, 150, 200 kGy at room temperature in the absence of air with a dose rate of 2.2 kGy/h. At low dose gelatin hydrogels incorporating all the available water were obtained. At higher doses above 50 kGy, the gelatin hydrogel samples show a curious shrinking phenomenon due to the relatively high crosslinking density level achieved, so part of the available water is squeezed out from the gel cage. The gelatin hydrogel samples were studied by mass fractionation analysis, by spectrophotometric and polarimetric analysis. Further characterization was made by FT-IR spectroscopy and by thermal analysis (DSC, DTA and TGA) of the dried gelatin samples after irradiation in comparison to a reference untreated sample.

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Journal of Thermal Analysis and Calorimetry
Authors: J. Sabín, G. Prieto, Elena Blanco, J. Ruso, Roberta Angelini, F. Bordi, and F. Sarmiento

Abstract  

The effects of concentration of gadolinium ions Gd3+ on dipalmitoyl L-α-phosphatidylcholine (DPPC) unilamellar vesicles in aqueous media were studied by photon correlation spectroscopy (PCS) and differential scanning calorimeter. The theoretical predictions of the colloidal stability of liposomes were followed using the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. Changes in the size of liposomes were observed as Gd3+ concentration increases, suggesting that this cation induces the aggregation of vesicles. To determine the effect of Gd3+ on the transition temperature (T c) and on the enthalpy (ΔH c) associated with the process differential scanning calorimetry (DSC) has been used. The addition of the metal ion provided DSC curves with different behavior to DPPC bilayer.

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Journal of Thermal Analysis and Calorimetry
Authors: J. Sabín, G. Prieto, Simona Sennato, Elena Blanco, Paula Messina, J. Ruso, Roberta Angelini, F. Bordi, and F. Sarmiento

Abstract  

The interactions of unilamellar vesicles obtained by the incorporation of (1,2,3,4,5,6)-tridecafluoro-hexadecane (F6H10 diblock) to dipalmitophosphatidyl-choline (DPPC), with Gd3+, Ca2+, Na+ ions were studied by electrophoretic measurements, dynamic light scattering and differential scanning calorimetry (DSC). Electrophoretic mobility measurements on unilamellar vesicles as a function of ion concentrations show that the vesicles adsorb the different ions employed. DSC has been used to determine the effect of diblock on the transition temperature (T c) and on the change of enthalpy (ΔH c) associated with the process.

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