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91.
Presti ML Ragusa S Trozzi A Dugo P Visinoni F Fazio A Dugo G Mondello L 《Journal of separation science》2005,28(3):273-280
Traditional hydrodistillation (HD), supercritical fluid extraction (SFE), organic solvent extraction (SE), and water microwave assisted hydrodistillation (MAHD) techniques were compared and evaluated for their effectiveness in the isolation of rosemary essential oil. The microwave assisted hydrodistillation technique was optimized in terms of both delivered power and time duration. The extracts/distillates were analyzed by GC and GC-MS. Microwave distillation, which exploits the physical action of microwaves on plants, showed a series of advantages over the other approaches: low cost, use of water in sample pre-treatment step, greatly reduced isolation time, and attainment of high quality essential oil distillate. Moreover, the absence of environmental impact of this innovative technique was also emphasized. 相似文献
92.
Riassunto In questa nota gli Autori stabiliscono dei principi variazionali che caratterizzano in maniera completa il più generale problema
ai limiti sia della statica sia della dinamica di una miscela isotropa di due solidi elastici lineari. Questi principi sono
del tutto generali poichè non si richiede agli stati o processi ammissibili di soddisfare ad alcuna delle equazioni di campo
e delle condizioni iniziali o al contorno. Tale risultato viene ottenuto esprimendo i problemi considerati in forma operazionale.
Il lavoro è stato eseguito nell’ambito del Gruppo Nazionale per la Fisica Matematica del C.N.R. 相似文献
Summary In this paper the Authors establish variational principles which characterize the most general boundary-value problem for statics and dynamics of an isotropic mixture of two linear elastic solids. These principles are completely general because the admissible states or processes are not required to meet any of the field equations, boundary or initial conditions and they are obtained by expressing the problems in operator form.
Il lavoro è stato eseguito nell’ambito del Gruppo Nazionale per la Fisica Matematica del C.N.R. 相似文献
93.
Gradinaru J Forni A Druta V Tessore F Zecchin S Quici S Garbalau N 《Inorganic chemistry》2007,46(3):884-895
New unsymmetrical [N2O2] tetradentate Schiff base complexes of Ni(II), Cu(II), Zn(II), and VO(II) were synthesized by template condensation of the tetradentate precursor 1-phenylbutane-1,3-dione mono-S-methylisothiosemicarbazone with o-hydroxybenzaldehyde or its 5-phenylazo derivative. They were characterized by elemental analysis, IR, UV-vis, electron spin resonance, and NMR spectroscopy, mass spectrometry, and magnetic measurements. The crystal structures of five of them have been determined by X-ray diffraction using, in some cases, synchrotron radiation. These compounds are characterized by a large thermal stability; their decomposition temperatures range from 240 up to 310 degrees C. Complexes with the phenylazo substituent were found to possess a large second-order nonlinear optical (NLO) response, as determined both by measurements of solution-phase direct current electric-field-induced second harmonic generation and by theoretical time-dependent density functional theory (TDDFT) calculations. The molecular hyperpolarizability was found to decrease in the order Zn(II) > Cu(II) > Ni(II) approximately VO(II). The active role of the metal in determining the NLO properties of the complexes was shown through an analysis of their UV-vis spectra, which revealed the presence of metal-to-ligand (in closed-shell complexes) and ligand-to-metal (in open-shell complexes) charge-transfer bands together with intra-ligand charge-transfer transitions. Assignment of the bands was based on the analysis of the TDDFT computed spectra. 相似文献
94.
95.
The incorporation of explicit ions to mimic the effect of ionic strength or to neutralize the overall charge on a system in free energy calculations using molecular dynamics simulations is investigated. The difference in the free energy of hydration between two triosephosphate isomerase inhibitors calculated at five different ion concentrations is used as an example. We show that the free energy difference can be highly sensitive to the presence of explicit ions even in cases where the mutation itself does not involve a change in the overall charge. The effect is most significant if the molecule carries a net charge close to the site mutated. Furthermore, it is shown that the introduction of a small number of ions can lead to very severe sampling problems suggesting that in practical calculations convergence can best be achieved by incorporating either no counterions or by simulating at high ionic strength to ensure sufficient sampling of the ion distribution. 相似文献
96.
de Oliveira MC Scarpellini M Neves A Terenzi H Bortoluzzi AJ Szpoganics B Greatti A Mangrich AS de Souza EM Fernandez PM Soares MR 《Inorganic chemistry》2005,44(4):921-929
The crystal structures and redox and UV-vis/EPR spectroscopic properties of two new mononuclear copper(II) complexes, [Cu(HL1)Cl2] (1) and [Cu(L1)Cl] (2), prepared through the reaction between copper(II) chloride and the ligand 2-[(bis(pyridylmethyl)amino)methyl]-4-methyl-6-formylphenol (HL1) under distinct base conditions, are reported along with solution studies. Also, we demonstrate that these CuII complexes are able to cleave unactivated peptide bonds from bovine serum albumin (BSA) and the thermostable enzyme Taq DNA polymerase at micromolar concentration, under mild pH and temperature conditions. The cleavage activity seems to be specific with defined proteolytic fragments appearing after protein treatment. The location of the specific cleavage sites was tentatively assigned to solvent-accessible portions of the protein. These are two of the most active Cu(II) complexes described to date, since their cleavage activity is detected in minutes and evidence is here presented for a hydrolytic mechanism mediating protein cleavage by these complexes. 相似文献
97.
98.
Alessandra Bernardi 《Journal of Pure and Applied Algebra》2008,212(6):1542-1559
The ideal of a Segre variety Pn1×?×Pnt?P(n1+1)?(nt+1)−1 is generated by the 2-minors of a generic hypermatrix of indeterminates (see [H.T. Hà, Box-shaped matrices and the defining ideal of certain blowup surface, J. Pure Appl. Algebra 167 (2-3) (2002) 203-224. MR1874542 (2002h:13020)] and [R. Grone, Decomposable tensors as a quadratic variety, Proc. Amer. Math. 43 (2) (1977) 227-230. MR0472853 (57 #12542)]). We extend this result to the case of Segre-Veronese varieties. The main tool is the concept of “weak generic hypermatrix” which allows us to treat also the case of projection of Veronese surfaces from a set of general points and of Veronese varieties from a Cohen-Macaulay subvariety of codimension 2. 相似文献
99.
100.
Maria Alessandra Ragusa 《Journal of Global Optimization》2008,40(1-3):361-368
In this note we prove a sufficient condition for commutators of fractional integral operators to belong to Vanishing Morrey
spaces VL
p,λ. In doing this we use an extension on Morrey spaces of an inequality by Fefferman and Stein concerning the sharp maximal
function and the fractional maximal function and related Morrey inequalities.
相似文献