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151.
Oreste Senofonte Nicola Violante Sonia D'Ilio Stefano Caimi Antonio Peri Sergio Caroli 《Microchemical Journal》2001,69(3)
In the framework of the Human Biology and Medicine Project of the National Program for Research in Antarctica (Programma Nazionale di Ricerche in Antartide, PNRA) a study was undertaken to explore the suitability of trace element determination in human hair as a tool for the early detection of the impact of extreme environmental conditions on the health of members of the Italian and French expeditions. This study included three campaigns, namely, the 1995–1996 expedition to the Italian base of Terra Nova Bay, as well as the 1997–1998 and 1998–1999 expeditions to both the Italian base of Terra Nova Bay and the Italian–French base of Dome C. Sampling of hair of participants in the expeditions was carried out both prior to departure and at the end of the period spent at the bases. As regards storage, pre-treatment and analysis of hair samples they were performed in accordance with previously established procedures. Acid-assisted microwave digestion was adopted as the best approach for preparing solutions for subsequent analysis by inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry. In the first part of this study, only the elements Ca, Cu, Fe, Mg and Zn were selected, while at a later stage it was decided to also include Co, Cr, Mn, Mo and Ni. Experimental results were subjected to basic statistical analysis to detect possible significant differences in element concentrations that occurred during the sojourn at the bases, with a view to identify possible remedial action to minimize adverse consequences. 相似文献
152.
153.
We propose an accurate and efficient method to compute vibrational spectra of molecules, based on exact diagonalization of an algebraically calculated matrix based on powers of Morse coordinate. The present work focuses on the 1D potential of diatomic molecules: as typical examples, we apply this method to the standard Lennard‐Jones oscillator, and to the ab initio potential of the H2 molecule. Global cm?1 accuracy is exhibited through the H2 spectrum, obtained through the diagonalization of a 30 × 30 matrix. This theory is at the root of a new method to obtain globally accurate vibrational spectral data in the context of the multi‐dimensional potential of polyatomic molecules, at an affordable computational cost. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
154.
Extended studies by e.p.r. and electronic spectroscopy on the effect of different non-polar solvents, temperature and disulfide concentration on the spectral properties of bis(dithiophosphato)copper(II), Cu[(RO)2PS2]2, complexes [R = Me, Et and i-Pr] are reported. The molar absorptivity and e.p.r. intensity are very sensitive to the shape and size of the remote ligand substituents and increase in the order: Me < Et < i-Pr. The nature of the solvent and time after dissolution are also important regarding the magnitude of the e.p.r. intensity and molar absorptivity which, 1 h after dissolution, do not follow Beer's law. The molar absorptivities obtained at a given CuII(R2–dtp)2 concentration increase in the solvent order: n-hexane < n-heptane < CCl4 < PhMe < PhH < CHCl3. Twenty-four hours after dissolution the same samples exhibit: (i) linearity between absorbance and concentration of CuII(R2–dtp)2; (ii) a significant increase in molar absorptivity which is not equal for all the complexes studied and follows the same substituent and solvent orders. Beer's law is satisfied above 5 × 10–4 M for [(RO)2PS2]2Cu (R = Et, i-Pr) and above 3 × 10–3 M for [(MeO)2PS2]Cu. A significant additional increase, ca. 30–40%, of molar absorptivity, is obtained by increasing the solution temperature from 20 to 50 °C. The molar absorbtivity remains unchanged during 2–3 days after reducing the temperature. Further increase of molecular absorbtivity appears after addition of the corresponding disulfide of dithiophosphate [(RO2)PS2–S2P(RO)2] to CuII[(RO)2PS2]2. The molar absorptivity of Cu[(i-PrO)2PS2]2 increases from 4.8 × 103 cm–1 M–1, 1 h after dissolving the complex up to 2 × 104 cm–1 M–1 after addition of the corresponding disulfide. The observed effects are explained on the basis of a self-redox reaction taking place in this type of sulfur containing copper(II) complexes. 相似文献
155.
Nicola Cufaro-Petroni 《Foundations of Physics》1992,22(11):1379-1401
In this paper the role of the mathematical probability models in the classical and quantum physics is shortly analyzed. In particular the formal structure of the quantum probability spaces (QPS) is contrasted with the usual Kolmogorovian models of probability by putting in evidence the connections between this structure and the fundamental principles of the quantum mechanics. The fact that there is no unique Kolmogorovian model reproducing a QPS is recognized as one of the main reasons of the paradoxical behaviors pointed out in the quantum theory from its early days.Paper written in honor of L. de Broglie. 相似文献
156.
S. De Nicola 《Applied physics. B, Lasers and optics》1994,58(6):439-442
We develop an approximate analysis based on the effective-index method to obtain the universal chart of the normalized parameters describing the mode dispersion of a two-dimensional diffused-channel wave-guide with an erfc-Gaussian index profile. We have shown that the Gaussian can well be approximated by an hyperbolic-secant-squared profile and we have compared our results with those obtained by using the effective-index method. 相似文献
157.
Fabio Nicola 《Journal d'Analyse Mathématique》2005,96(1):297-311
We give necessary and sufficient conditions for a lower bound with a gain of 3/2 derivatives (the so-called Weak-Hörmander inequality) for a class of systems with double characteristics. 相似文献
158.
159.
Gurtin recently proposed a strain-gradient theory for crystal plasticity in which the gradient effect originates from a defect energy that characterizes energy storage due to the presence of a net Burgers vector. Here we consider a number of different possibilities for this energy: specifically, working within a simple two-dimensional framework, we compare predictions of the theory with results of discrete-dislocation simulations of stress relaxation in thin films. Our objective is to investigate which specific defect energies are capable of capturing the size-dependent response of such systems for different crystal orientations. 相似文献
160.
Stabilization of Titanium Dioxide Nanoparticles at the Surface of Carbon Nanomaterials Promoted by Microwave Heating
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Rui Zhang Prof. Dr. Saveria Santangelo Dr. Enza Fazio Prof. Dr. Fortunato Neri Dr. Massimiliano D'Arienzo Prof. Dr. Franca Morazzoni Prof. Dr. Yihe Zhang Prof. Dr. Nicola Pinna Dr. Patrícia A. Russo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(42):14901-14910
TiO2 is frequently combined with carbon materials, such as reduced graphene oxide (RGO), to produce composites with improved properties, for example for photocatalytic applications. It is shown that heating conditions significantly affect the interface and photocatalytic properties of TiO2@C, and that microwave irradiation can be advantageous for the synthesis of carbon‐based materials. Composites of TiO2 with RGO or amorphous carbon were prepared from reaction of titanium isopropoxide with benzyl alcohol. During the synthesis of the TiO2 nanoparticles, the carbon is involved in reactions that lead to the covalent attachment of the oxide, the extent of which depends on the carbon characteristics, heating rate, and mechanism. TiO2 is more efficiently stabilized at the surface of RGO than amorphous carbon. Rapid heating of the reaction mixture results in a stronger coupling between the nanoparticles and carbon, more uniform coatings, and smaller particles with narrower size distributions. The more efficient attachment of the oxide leads to better photocatalytic performance. 相似文献