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1.
A. Puiu G. Giubileo G. Addolorato L. Revelli G. Gasbarrini R. Bellantone A. D’Amore C. P. Lombardi C. Carrozza 《Laser Physics》2007,17(4):448-452
Nowadays, there is high demand for sensitive gas sensors both for human and environmental monitoring. This paper deals with a high-resolution (0.2 ppb) laser-based photoacoustic spectroscopic system realized at ENEA Frascati, Italy, applied for monitoring stress in scuba divers during sustained immersion by analyzing breath samples. Blood tests and psychometric tests for scuba divers were performed at Catholic University in Rome. Results will be reported and discussed. 相似文献
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Rigorous definitions are presented for the kinematic angular momentum K of a system of classical particles (a concept dual to the conventional angular momentum J), the angular momentum L(xi) associated with the moments of inertia, and the contributions to the total kinetic energy of the system from various modes of the motion of the particles. Some key properties of these quantities are described-in particular, their invariance under any orthogonal coordinate transformation and the inequalities they are subject to. The main mathematical tool exploited is the singular value decomposition of rectangular matrices and its differentiation with respect to a parameter. The quantities introduced employ as ingredients particle coordinates and momenta, commonly available in classical trajectory studies of chemical reactions and in molecular dynamics simulations, and thus are of prospective use as sensitive and immediately calculated indicators of phase transitions, isomerizations, onsets of chaotic behavior, and other dynamical critical phenomena in classical microaggregates, such as nanoscale clusters. 相似文献
3.
Ilaria Serafini Livia Lombardi Claudia Fasolato Manuel Sergi Francesca Di Ottavio Fabio Sciubba 《Natural product research》2019,33(7):1040-1051
AbstractIn this paper, the application of a multi-analytical approach for the characterisation of synthetic and natural dyes in a historical textile is presented. The work is focused on a historical dress of a Sicilian noblewoman, dating from about 1865–1870. Firstly, SERS on fibre was performed, in order to individuate the classes of dyes employed. The SERS spectra suggested the presence of two main dyes: mauveine and orcein. In order to confirm these preliminary results, two different extraction protocols were applied. The extracts obtained were analysed by ESI-MS, MALDI-ToF and UHPCL-MS analyses, confirming the SERS results. In particular, the application of the ammonia mild extraction technique allowed to selectively extract the phenoxazonic dyes, separating them already in the extraction step from the synthetic ones. Thanks to this multi-analytical approach, this dress could be considered as one of the first examples of employment of synthetic dyes in association with natural ones. 相似文献
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Shirakawa S Lombardi PJ Leighton JL 《Journal of the American Chemical Society》2005,127(28):9974-9975
A highly diastereo- and enantioselective [3 + 2] acylhydrazone-enol ether cycloaddition mediated by a simple chiral silane Lewis acid is described. The reactions are highly practical, as demonstrated by a larger scale (5 g of the hydrazone) reaction in which the product was obtained after recrystallization in 93% yield and 99% ee. Evidence for a stepwise mechanism and a model for the asymmetric induction are presented, as well. 相似文献
7.
Martinez-Diaz MV Rodriguez-Morgade MS Feiters MC van Kan PJ Nolte RJ Stoddart JF Torres T 《Organic letters》2000,2(8):1057-1060
[formula: see text] New unsymmetrically substituted DB24C8-phthalocyanines, which are able to form complexes with suitable dialkylammonium cations, have been prepared. These complexes most probably have a pseudorotaxane geometry. 相似文献
8.
Vivoni A Birke R Lombardi J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(3):535-544
We present a method that simplifies the refinement of force constants in normal mode calculations and makes the results more reliable. The method avoids normal mode crossings by constraining the force constants during refinement. It was tested with pyrrole, imidazole, benzene, pyridine, pyrimidine, aniline and adenine using a Urey-Bradley force field. The global error of the frequency fit for these molecules was 0.61%. The method reproduced with fewer parameters the accuracy of similar calculations of the single ring aromatic compounds. It improved the accuracy and isotopic shifts of previous empirical calculations of adenine by 40%. The C-C and C-N stretchings differed by less than 7% from the values of force constant-bond length empirical relations. 相似文献
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[reaction: see text] An expedient synthesis of diverse 2-amino-4-heteroarylpyrimidines via a 2-chloropyrimidine intermediate is described. A series of potentially biologically active analogues have been synthesized in two parallel steps to afford focused arrays. 相似文献