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Cataldo F.,Lupi Chemical Research | Ragni P.,CNR Methodological Chemistry Institute | Iglesias-Groth S.,Institute of Astrophysics of Canarias | Manchado A.,Institute of Astrophysics of Canarias
Journal of Radioanalytical and Nuclear Chemistry | Year: 2011

The sulphur-containing proteinaceous amino acids l-cysteine, l-cystine and l-methionine were irradiated in the solid state to a dose of 3.2 MGy. This dose corresponds to that delivered by radionuclide decay in a timescale of 1.05 × 109 years to the organic matter buried at a depth >20 m in comets and asteroids. The purity of the sulphur-containing amino acids was studied by differential scanning calorimetry (DSC) before and after the solid state radiolysis and the preservation of the chirality after the radiolysis was studied by chirooptical methods (optical rotatory dispersion, ORD) and by FT-IR spectroscopy. Although the high radiation dose of 3.2 MGy delivered, all the amino acids studied show a high radiation resistance. The best radiation resistance was offered by l-cysteine. The radiolysis of l-cysteine leads to the formation of l-cystine. The radiation resistance of l-methionine is not at the level of l-cysteine but also l-methionine is able to survive the dose of 3.2 MGy. Furthermore in all cases examined the preservation of chirality after radiolysis was clearly observed by the ORD spectroscopy although a certain level of radioracemization was measured in all cases. The radioracemization is minimal in the case of l-cysteine and is more pronounced in the case of l-methionine. In conclusion, the study shows that the sulphur-containing amino acids can survive for 1.05 × 109 years and, after extrapolation of the data, even to the age of the Solar System i.e. to 4.6 × 10 9 years. © 2010 Akadémiai Kiadó, Budapest, Hungary.


Cataldo F.,Lupi Chemical Research | Cataldo F.,University of Rome Tor Vergata | Ursini O.,CNR Institute of Neuroscience | Angelini G.,CNR Institute of Neuroscience
Fullerenes Nanotubes and Carbon Nanostructures | Year: 2011

It is shown that both graphite oxide (GO) and oxidized graphene nanoribbons (OGN) can be safely reduced by using hydrogen iodide (hydroiodic acid). FT-IR spectroscopy and TGA-DTG were used to show that HI 67% is able to lead to a complete reduction of GO while HI 57% is less effective. In terms of FT-IR spectroscopy and thermal analysis, the HI-reduced GO is almost identical to the N2H4-reduced GO. Hydrogen iodide 57% is in any case effective in reducing OGN. Since hydrazine is extremely toxic and explosive when anhydrous, it is suggested to use HI (preferably at 67% concentration) as alternative, safe and effective reducing agent. Copyright © Taylor & Francis Group, LLC.


Cataldo F.,Lupi Chemical Research | Ragni P.,CNR Methodological Chemistry Institute | Iglesias-Groth S.,Institute of Astrophysics of Canarias | Manchado A.,Institute of Astrophysics of Canarias
Journal of Radioanalytical and Nuclear Chemistry | Year: 2011

The thermal behaviour of 21 proteinaceous l-amino acids either as pristine samples and also as radiolyzed (3.2 MGy) samples was studied with the differential scanning calorimeter. The onset and peak melting point as well as the melting enthalpy of all samples before and after the radiation treatment was measured and reported. The residual amount of each amino acid survived to the radiation dose of 3.2 MGy (N γ) was measured from the melting enthalpies before and after radiolysis and hence the radiation resistance of each amino acid has been determined. The radiolysis causes a systematic reduction of the melting enthalpy and a shift of the onset and peak melting point to lower values. It is shown that N γ does not correlate with the melting points of the amino acids but shows a correlation with the entity of the shift of the melting point peaks occurred after radiolysis. Such correlation instead does not exist between the N γ parameter and the onset melting points of the amino acids. An explanation of such lack of correlation was given. Furthermore, a general relationship has been found between the amino acids melting point peak measured on pristine samples and the melting point peaks after solid state radiolysis. Such relationship can be used to predict roughly the expected melting point after radiolysis at 3.2 MGy of any given amino acid. The last part of the study was dedicated in the attempt to find a correlation between the N γ parameter and the amount of the amino acids survived the radiolysis R γ as measured by spectropolarimetry (ORD spectroscopy). A general trend was found in the connection between the N γ and R γ parameters but not a very strong correlation. © 2010 Akadémiai Kiadó, Budapest, Hungary.


Cataldo F.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Cataldo F.,Lupi Chemical Research | Cataldo F.,University of Rome Tor Vergata | Compagnini G.,University of Catania | And 8 more authors.
Carbon | Year: 2010

Graphene nanoribbons were synthesized by oxidative unzipping of single-wall carbon nanotubes (SWCNTs). The nanoribbons produced from SWCNTs were characterized using FT-IR, Raman and X-ray photoelectron spectroscopy. For the morphological study of the product obtained from the SWCNT unzipping reaction, transmission electron microscopy and atomic force microscopy were used, confirming the typical graphene nanoribbon structure. © 2010 Elsevier Ltd. All rights reserved.


Cataldo F.,Lupi Chemical Research | Cataldo F.,University of Rome Tor Vergata | Lilla L.,CNR Institute of Neuroscience | Ursini O.,CNR Institute of Neuroscience
Fullerenes Nanotubes and Carbon Nanostructures | Year: 2013

Fullerene black (FB) is the raw carbon soot produced during fullerene synthesis by arcing graphite electrodes under helium. When FB is extracted with toluene to remove C 60 and C 70 fullerenes (but not higher fullerenes), the extracted fullerene black (EFB) is produced. FB and EFB were brominated with liquid bromine and sonication in mild conditions. For comparison, graphite and N220 grade furnace carbon black were brominated in an ultrasonic field. The resulting brominated carbons were studied by thermogravimetric analysis, derivative thermogravimetry, differential thermal analysis and FT-IR spectroscopy. Under the conditions adopted, graphite was found completely unreactive with bromine while N220 carbon black yielded a brominated derivative with the composition C 65Br. FB and EFB produced brominated derivatives with the composition C 16Br. With the thermal analysis it was possible to distinguish between bromine adsorbed on fullerenic sites and bromine residual compound so that the brominated derivatives of FB and EFB can be described as [(C 16 (Br 0.7) fullerenic(Br 0.3) residual] and [C 16(Br 0.5) fullerenic(Br 0.5) residual], respectively. The incredible chemical adsorption power (chemisorption) of FB and EFB against N220 carbon black is disclosed. © Taylor & Francis Group, LLC.

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