Neutron bombardment of single wall carbon nanohorn (SWCNH): DSC determination of the stored Wigner-Szilard energy

Single wall carbon nanohorn (SWCNH) were neutron-bombarded to a dose of 3.28 × 10¹⁶ n/cm². The Wigner or stored energy was determined by a differential scanning calorimeter and was found 5.49 J/g, 50 times higher than the Wigner energy measured on graphite flakes treated at the same neutron dose. The activation energy for the thermal annealing of the accumulated radiation damage in SWCNH was determined in the range 6.3–6.6 eV against a typical activation energy for the annealing of the radiation-damaged graphite which is in the range of 1.4–1.5 eV. Furthermore the stored energy in neutron-damaged SWCNH is released at 400–430 °C while the main peak in the neutron-damaged graphite occurs at 200–220 °C. The radiation damaged SWCNH were examined with FT-IR spectroscopy showing the formation of acetylenic and aliphatic moieties suggesting the aromatic C=C breakdown caused by the neutron bombardment.     

Some remarks on strong unique continuation for the laplace operator and its powers

ABSTRACT

Some spectral properties of magnetic Schrödinger and Dirac operators perturbed by long range magnetic fields are investigated. If the intensity of the field is small enough, a better location of the perturbed spectrum is given. In particular, if the unperturbed spectrum is discrete, we show that the perturbed eigenvalues are given in terms of an absolutely convergent series with respect to a magnetic parameter, from which the usual asymptotic expansion can be derived.     

A detailed analysis of the properties of radiolyzed proteinaceous amino acids

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.     

Frobenius semisimplicity for convolution morphisms

Mathematische Zeitschrift - This article concerns properties of mixed $$\ell $$ -adic complexes on varieties over finite fields, related to the action of the Frobenius automorphism. We establish a...     

Surface oxidation of rubber crumb with ozone

Rubber crumb derived from the grinding of used truck tread and tyres is used as a low cost filler in rubber compounds based on diene rubber. In order to expand its application to other fields, the surface modification of the rubber crumb could be an interesting and feasible solution. In fact, the surface modification of rubber crumb may be used as a tool to expand its use in applications to compounds with polar rubber matrices or where hydrophilic surface of the rubber crumb could be desirable, for example in water-based dispersion or as filler for asphalt. In the present work, ozone has been used as the active agent to cause surface oxidation and functionalisation of rubber crumb in a fluidized bed reaction. The rubber crumb reacts swiftly with ozone producing CO₂ in the initial stages of reaction and then leading to the desired surface oxidized product. The rate constant of the reaction between ozone and rubber crumb has been determined by FT-IR spectroscopy, monitoring the consumption of ozone in the gas phase in the presence of the crumb. A rate constant value of 5.03 × 10⁻³ s⁻¹  g⁻¹ of rubber crumb was determined. The degree of the surface oxidation of the rubber crumb can be determined by FT-IR spectroscopy using as reference the intensity of the ketone band at about 1710 cm⁻¹. Additionally the nominal ratio between the amount of ozone (in mg) reacted with rubber crumb (in g) can be used as a parameter for the degree of the surface oxidation. The surface oxidized rubber crumb shows surface acidity and hydrophilicity. Thermogravimetric analysis, differential thermal analysis and pyrolysis-GC clearly demonstrate that the ozonization of the rubber crumb is directed exclusively to the surface of the crumb and does not affect the bulk properties at all.     

Sull'equilibrio relativo magnetodinamico di masse gassose elettricamente conduttrici,rotanti e soggette alla propria gravitazione

Sunto Si considera l'equilibrio relativo magnetodinamico di masse gassose elettricamente couduttrici rotanti e gravitanti. Si stabiliscono in modo generale le equazioni che reggono il fenomeno, supponendo che oltre a un moto di rotazione intorno a un asse di simmetria, vi sia anche movimento nei piani meridiani e che il campo magnetico che si genera sia nell'insieme poloidale e toroidale. A Bruno Finzi nel suo 70^mo compleanno. Entrata in Redazione il 6 luglio 1969.     

Fullerene-Like Structures as Interaction Sites between Carbon Black and Rubber

Ball-milling of N660 carbon black and graphite causes a deep activation of its surface activity which can be measured by a significant increase in the bound rubber level and in the amount of grafted rubber in comparison to the pristine untreated samples. The bound rubber measurement has been done also on a natural rubber masterbatch filled with extracted fullerene carbon black (EFCB). Also in this case extremely high levels of rubber grafting have been achieved in comparison to pure untreated graphite. It is discussed and demonstrated that the fullerene-like nanostructures in carbon blacks play a key role in the formation of bound rubber phenomenon and in grafting natural rubber on carbon black surface.     

High performance electrochemical sensor based on modified screen-printed electrodes with cost-effective dispersion of nanostructured carbon black

A novel sensor based on a screen-printed electrode (SPE) modified with a stable dispersion of commercially available carbon black (CB) N220 was developed. This probe showed significantly enhanced electrochemical activity relative to a bare SPE when tested with ferricyanide, epinephrine, norepinephrine, benzoquinone and NADH. When challenged in amperometric batch mode with NADH, the response was stable and revealed a linear dependence up to 2·10^?4 mol L^?1 with a detection limit of 3·10^?7 mol L^?1. The analytical performance, coupled with the low cost of the CB nanomaterial, suggests that this sensor holds promise for electrochemical applications.