Abstract: Nanofluids are a new class of fluids that could significantly improve the thermal prope... more Abstract: Nanofluids are a new class of fluids that could significantly improve the thermal properties of fluids used as thermal vectors. They are obtained by dispersing in common fluids (water, glycol, oil) solid nanoparticles (diameter< 100 nm) of different materials (metal oxides, metals, carbon nanotubes)[1].
In the present work, we investigated the scattering and spectrally resolved absorption properties... more In the present work, we investigated the scattering and spectrally resolved absorption properties of nanofluids consisting in aqueous and glycol suspensions of single-wall carbon nanohorns. The characteristics of these nanofluids were evaluated in view of their use as sunlight absorber fluids in a solar device. The observed nanoparticle-induced differences in optical properties appeared promising, leading to a considerably higher sunlight absorption with respect to the pure base fluids. Scattered light was found to be not more than about 5% with respect to the total attenuation of light. Both these effects, together with the possible chemical functionalization of carbon nanohorns, make this new kind of nanofluids very interesting for increasing the overall efficiency of the sunlight exploiting device.
A new method for electrochemical titrations is proposed, based on the redox transformation of the... more A new method for electrochemical titrations is proposed, based on the redox transformation of the test species by means of a controlled-potential pulsed current, followed by measurement of the potential in the intervals between the current pulses: the end-point is found by means of Sorensen's linearization technique. Investigations on various metal ions (Ag +, CU'+, Cd*+, Pb*+) have shown that the accuracy and sensitivity, which depend on the nature of the species titrated, are comparable with those of other titration techniques. The method permits analytical separations and determinations of metal ions in mixtures. No particularly elaborate instrumentation is required and the apparatus described is simple to use, reliable and inexpensive.
2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC), 2011
Single Wall Carbon Nanohoms (SWCNHs) are innovative carbon nanostructures belonging to the thrivi... more Single Wall Carbon Nanohoms (SWCNHs) are innovative carbon nanostructures belonging to the thriving family of carbon nanotubes and fullerenes. They have being studied up to now mainly as non-cytotoxic drug carriers [1], but they are interesting for a huge number of applications such as electronics [2], hydrogen and methane storage [3] and renewable energies. In this paper we investigate their optical properties in view of their use as direct sunlight absorbers in solar thermal devices and as reference standard in Biological Tissue Optics.
SIMS). The crystals obtained have been structurally characterized by X-ray diffraction; the oxyge... more SIMS). The crystals obtained have been structurally characterized by X-ray diffraction; the oxygen content has been determined both by structural examination and by iodometric titration, and the electrical resistivity has been measured by the four-thread technique. SIMS has been used to examine the growth features on the (001) faces of the crystals. Impurity inclusions, ionic species from metals with different oxidation state, homo-and hetero-metal clusters, their ionic yields and distribution in different matrices could usefully be compared to information obtained with traditional methodologies utilized in this field. Results obtained by SIMS for both NdBa 2 Cu 3 O 7À and EuBa 2 Cu 3 O 7À single crystals could provide new instruments in estimating the property of superconducting materials. For example, the reaction of Al-Cu substitution was observed on the crystal surface, as indicated by mixed cluster signals on the positive and negative ion spectra confirming the already observed interaction between material from crucible and REBa 2 Cu 3 O 7À (RE = Rare Earths, except for Ce, Pr and Tb).
International Journal of Mass Spectrometry and Ion Processes, 1996
The process of TiO2 evolution from titanium diisopropoxide bis-2,4-pentanedionate precursor on ni... more The process of TiO2 evolution from titanium diisopropoxide bis-2,4-pentanedionate precursor on nickel and titanium supports was followed by secondary ion mass spectrometry. Concentration depth profiles of rutile (TiO2) at higher temperatures showed completely different patterns for the two supports, indicating the influence of the base metal on the formation and properties of the oxide coating.The formation and surface accumulation of
A method for large-scale production of Single Wall Carbon Nanohorns (SWCNH) in a prototype reacto... more A method for large-scale production of Single Wall Carbon Nanohorns (SWCNH) in a prototype reactor was tested with optimal thermodynamic conditions that favour high quality material formation at rates of about 100 g/h. The first productions demonstrated the excellent capability and flexibility of the approach. The plant typology that can be easily scaled up to tens the present scale, making possible to propose materials based on SWCNHs for real uses such as in hydrogen storage. In this framework, pristine and oxidized materials were characterized and tested.
Biochimica et Biophysica Acta (BBA) - Nucleic Acids and Protein Synthesis, 1976
A soluble RNA with a molecular weight between 15 000 and 23 000 was extracted from calf thymus an... more A soluble RNA with a molecular weight between 15 000 and 23 000 was extracted from calf thymus and chromatographically purified. The RNA was slightly soluble in doxane (approx. 2.5 mug/ml) and RNA-dioxane solutions were used to fill a cell (452.02 pF capacitance) to which static electric fields of variable strength were applied. The dielectric permittivity of the solutions was measured at a fixed time interval after the application of the electric field. The RNA solutions showed a dielectric increment proportional to the strength of the applied field and to the RNA concentration. The existence of a hystersis effect was proven and the effect of the electric field on the RNA molecule might be related to a dielectric saturation phenomenon parallel to long-term changes of the molecule.
ABSTRACT The preliminary results concerning the preparation of a new hybrid nanocomposite materia... more ABSTRACT The preliminary results concerning the preparation of a new hybrid nanocomposite material are here presented. The process was achieved by various steps starting from the deposition of anatase TiO2 on a powder of single wall carbon nanohorns (SWCNHs) via MOCVD by using titanium tetraisopropoxide Ti(OiPr)4 as the precursor, then the dispersion and sonication of the obtained hybrid material in water, followed by the deposition onto a conducting ITO substrate, which finally led to the growth of the strelitzia flower-like titania via RF reactive magnetron sputtering employing a metal titanium target. The new hybrid nanocomposite material was characterized by scanning electron microscopy and X-ray diffraction. The particular experimental conditions in which this singular growth was observed, are discussed.
An updated dual-isotope method by mass-resolved ion-scattering spectrometry using simultaneously ... more An updated dual-isotope method by mass-resolved ion-scattering spectrometry using simultaneously two isotopes of Ne+ as primary-ion beam was developed for the study of neutralization phenomena occurring with low-energy (0.5–1.5keV) ions scattered from the surface of noble/transition metals (Cu, Ag, Au and Pt). Data for the characteristic velocity νc were estimated, namely 2.05×105ms−1 (Cu), 2.15×105ms−1 (Ag), 1.90×105ms−1 (Au) and 1.67×105ms−1 (Pt),
Abstract: Nanofluids are a new class of fluids that could significantly improve the thermal prope... more Abstract: Nanofluids are a new class of fluids that could significantly improve the thermal properties of fluids used as thermal vectors. They are obtained by dispersing in common fluids (water, glycol, oil) solid nanoparticles (diameter< 100 nm) of different materials (metal oxides, metals, carbon nanotubes)[1].
In the present work, we investigated the scattering and spectrally resolved absorption properties... more In the present work, we investigated the scattering and spectrally resolved absorption properties of nanofluids consisting in aqueous and glycol suspensions of single-wall carbon nanohorns. The characteristics of these nanofluids were evaluated in view of their use as sunlight absorber fluids in a solar device. The observed nanoparticle-induced differences in optical properties appeared promising, leading to a considerably higher sunlight absorption with respect to the pure base fluids. Scattered light was found to be not more than about 5% with respect to the total attenuation of light. Both these effects, together with the possible chemical functionalization of carbon nanohorns, make this new kind of nanofluids very interesting for increasing the overall efficiency of the sunlight exploiting device.
A new method for electrochemical titrations is proposed, based on the redox transformation of the... more A new method for electrochemical titrations is proposed, based on the redox transformation of the test species by means of a controlled-potential pulsed current, followed by measurement of the potential in the intervals between the current pulses: the end-point is found by means of Sorensen's linearization technique. Investigations on various metal ions (Ag +, CU'+, Cd*+, Pb*+) have shown that the accuracy and sensitivity, which depend on the nature of the species titrated, are comparable with those of other titration techniques. The method permits analytical separations and determinations of metal ions in mixtures. No particularly elaborate instrumentation is required and the apparatus described is simple to use, reliable and inexpensive.
2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC), 2011
Single Wall Carbon Nanohoms (SWCNHs) are innovative carbon nanostructures belonging to the thrivi... more Single Wall Carbon Nanohoms (SWCNHs) are innovative carbon nanostructures belonging to the thriving family of carbon nanotubes and fullerenes. They have being studied up to now mainly as non-cytotoxic drug carriers [1], but they are interesting for a huge number of applications such as electronics [2], hydrogen and methane storage [3] and renewable energies. In this paper we investigate their optical properties in view of their use as direct sunlight absorbers in solar thermal devices and as reference standard in Biological Tissue Optics.
SIMS). The crystals obtained have been structurally characterized by X-ray diffraction; the oxyge... more SIMS). The crystals obtained have been structurally characterized by X-ray diffraction; the oxygen content has been determined both by structural examination and by iodometric titration, and the electrical resistivity has been measured by the four-thread technique. SIMS has been used to examine the growth features on the (001) faces of the crystals. Impurity inclusions, ionic species from metals with different oxidation state, homo-and hetero-metal clusters, their ionic yields and distribution in different matrices could usefully be compared to information obtained with traditional methodologies utilized in this field. Results obtained by SIMS for both NdBa 2 Cu 3 O 7À and EuBa 2 Cu 3 O 7À single crystals could provide new instruments in estimating the property of superconducting materials. For example, the reaction of Al-Cu substitution was observed on the crystal surface, as indicated by mixed cluster signals on the positive and negative ion spectra confirming the already observed interaction between material from crucible and REBa 2 Cu 3 O 7À (RE = Rare Earths, except for Ce, Pr and Tb).
International Journal of Mass Spectrometry and Ion Processes, 1996
The process of TiO2 evolution from titanium diisopropoxide bis-2,4-pentanedionate precursor on ni... more The process of TiO2 evolution from titanium diisopropoxide bis-2,4-pentanedionate precursor on nickel and titanium supports was followed by secondary ion mass spectrometry. Concentration depth profiles of rutile (TiO2) at higher temperatures showed completely different patterns for the two supports, indicating the influence of the base metal on the formation and properties of the oxide coating.The formation and surface accumulation of
A method for large-scale production of Single Wall Carbon Nanohorns (SWCNH) in a prototype reacto... more A method for large-scale production of Single Wall Carbon Nanohorns (SWCNH) in a prototype reactor was tested with optimal thermodynamic conditions that favour high quality material formation at rates of about 100 g/h. The first productions demonstrated the excellent capability and flexibility of the approach. The plant typology that can be easily scaled up to tens the present scale, making possible to propose materials based on SWCNHs for real uses such as in hydrogen storage. In this framework, pristine and oxidized materials were characterized and tested.
Biochimica et Biophysica Acta (BBA) - Nucleic Acids and Protein Synthesis, 1976
A soluble RNA with a molecular weight between 15 000 and 23 000 was extracted from calf thymus an... more A soluble RNA with a molecular weight between 15 000 and 23 000 was extracted from calf thymus and chromatographically purified. The RNA was slightly soluble in doxane (approx. 2.5 mug/ml) and RNA-dioxane solutions were used to fill a cell (452.02 pF capacitance) to which static electric fields of variable strength were applied. The dielectric permittivity of the solutions was measured at a fixed time interval after the application of the electric field. The RNA solutions showed a dielectric increment proportional to the strength of the applied field and to the RNA concentration. The existence of a hystersis effect was proven and the effect of the electric field on the RNA molecule might be related to a dielectric saturation phenomenon parallel to long-term changes of the molecule.
ABSTRACT The preliminary results concerning the preparation of a new hybrid nanocomposite materia... more ABSTRACT The preliminary results concerning the preparation of a new hybrid nanocomposite material are here presented. The process was achieved by various steps starting from the deposition of anatase TiO2 on a powder of single wall carbon nanohorns (SWCNHs) via MOCVD by using titanium tetraisopropoxide Ti(OiPr)4 as the precursor, then the dispersion and sonication of the obtained hybrid material in water, followed by the deposition onto a conducting ITO substrate, which finally led to the growth of the strelitzia flower-like titania via RF reactive magnetron sputtering employing a metal titanium target. The new hybrid nanocomposite material was characterized by scanning electron microscopy and X-ray diffraction. The particular experimental conditions in which this singular growth was observed, are discussed.
An updated dual-isotope method by mass-resolved ion-scattering spectrometry using simultaneously ... more An updated dual-isotope method by mass-resolved ion-scattering spectrometry using simultaneously two isotopes of Ne+ as primary-ion beam was developed for the study of neutralization phenomena occurring with low-energy (0.5–1.5keV) ions scattered from the surface of noble/transition metals (Cu, Ag, Au and Pt). Data for the characteristic velocity νc were estimated, namely 2.05×105ms−1 (Cu), 2.15×105ms−1 (Ag), 1.90×105ms−1 (Au) and 1.67×105ms−1 (Pt),
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Papers by Cesare Pagura