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41.
Martyn R. Dixon Martin J. Evans Antonio Tortora 《Central European Journal of Mathematics》2010,8(1):22-25
A subgroup H of a group G is inert if |H: H ∩ H
g
| is finite for all g ∈ G and a group G is totally inert if every subgroup H of G is inert. We investigate the structure of minimal normal subgroups of totally inert groups and show that infinite locally
graded simple groups cannot be totally inert. 相似文献
42.
43.
Nardis S Stefanelli M Mohite P Pomarico G Tortora L Manowong M Chen P Kadish KM Fronczek FR McCandless GT Smith KM Paolesse R 《Inorganic chemistry》2012,51(6):3910-3920
Two different methods for the regioselective nitration of different meso-triarylcorroles leading to the corresponding β-substituted nitrocorrole iron complexes have been developed. A two-step procedure affords three Fe(III) nitrosyl products-the unsubstituted corrole, the 3-nitrocorrole, and the 3,17-dinitrocorrole. In contrast, a one-pot synthetic approach drives the reaction almost exclusively to formation of the iron nitrosyl 3,17-dinitrocorrole. Electron-releasing substituents on the meso-aryl groups of the triarylcorroles induce higher yields and longer reaction times than what is observed for the synthesis of similar triarylcorroles with electron-withdrawing functionalities, and these results can be confidently attributed to the facile formation and stabilization of an intermediate iron corrole π-cation radical. Electron-withdrawing substituents on the meso-aryl groups of triarylcorrole also seem to labilize the axial nitrosyl group which, in the case of the pentafluorophenylcorrole derivative, results in the direct formation of a disubstituted iron μ-oxo dimer complex. The influence of meso-aryl substituents on the progress and products of the nitration reaction was investigated. In addition, to elucidate the most important factors which influence the redox reactivity of these different iron nitrosyl complexes, selected compounds were examined by cyclic voltammetry and thin-layer UV-visible or FTIR spectroelectrochemistry in CH(2)Cl(2). 相似文献
44.
Roberto Paolesse Luca Tortora Donato Monti Sara Nardis Manuela Stefanelli Arnaldo D’Amico Corrado Di Natale 《Procedia Chemistry》2009,1(1):180-183
A facile and straightforward way to deposit nanostructured porphyrin films onto quartz surfaces is presented. The particular peripheral functionalization on the macrocycle is exploited to drive the formation of aggregates in solution, which then spontaneously deposit as ordered solid layers. Film deposition is then achieved by simple dipping the quartz slide into a solution containing porphyrin aggregates and waiting the formation of the related thin films. QCMs covered with different metalloporphyrin derivatives have been exposed to some model VOCs, showing in general good performances especially in all the cases where film morphology is fundamental for sensing interactions. 相似文献
45.
S Zhou YA Nastishin MM Omelchenko L Tortora VG Nazarenko OP Boiko T Ostapenko T Hu CC Almasan SN Sprunt JT Gleeson OD Lavrentovich 《Physical review letters》2012,109(3):037801
Using a magnetic Frederiks transition technique, we measure the temperature and concentration dependences of splay K_{1}, twist K_{2}, and bend K_{3} elastic constants for the lyotropic chromonic liquid crystal sunset yellow formed through noncovalent reversible aggregation of organic molecules in water. K_{1} and K_{3} are comparable to each other and are an order of magnitude higher than K_{2}. At higher concentrations and lower temperatures, K_{1} and the ratios K_{1}/K_{3} and K_{1}/K_{2} increase, which is attributed to elongation of self-assembled lyotropic chromonic liquid crystal aggregates, a feature not found in conventional thermotropic and lyotropic liquid crystals formed by covalently bound units of a fixed length. 相似文献
46.
Nicolaou KC Lizos DE Kim DW Schlawe D de Noronha RG Longbottom DA Rodriquez M Bucci M Cirino G 《Journal of the American Chemical Society》2006,128(13):4460-4470
The marine-derived halipeptins A (1a) and D (1d) and their analogues 3a, 3d and 4a, 4d were synthesized starting from building blocks 10, 13, 14a or 14d, 15, and 16. The first strategy for assembling the building blocks, involving a macrolactamization reaction to form the 16-membered ring hydroxy thioamide 52d as a precursor, furnished the epi-isoleucine analogue (4d) of halipeptin D, whereas a second approach involving thiazoline formation prior to macrolactamization led to a mixture of halipeptins A (1a) and D (1d) and their analogues 3a, 3d (epimers at the indicated site) and 4a, 4d (epimers at the indicated site). The same route starting with D-Ala resulted in the exclusive formation of the epimeric halipeptin D analogue 3d. The synthesized halipeptins, together with the previously constructed oxazoline analogues 5d and 6d, were subjected to biological evaluation revealing anti-inflammatory properties for 1a, 1d, and 6d while being noncytotoxic against human colon cancer cells (HCT-116). 相似文献
47.
We consider the linearized compressible Navier-Stokes equation near a parallel flow in a cylindrical domain restricting our
study to perturbations periodic in the generatrix direction. For any parameter values, we show that the initial value linear
evolution problem is solved by the direct sum of a (strictly) contraction semi-group and an analytic semi-group. Any unbounded
in time solution of this linear problem comes from isolated eigenvalues with finite multiplicities, which have non negative
real part, and whose imaginary part is bounded. In addition, we precise the structure of the spectrum of the generator of
the semi-group, locating the essential spectrum stricly on the left side of the complex plane.
Sunto Si linearizzano le equazioni di Navier-Stokes comprimibili attorno ad un moto lineare in un cilindro. Senza imporre restrizioni sul moto di base, si studia il problema lineare per perturbazioni periodiche nella direzione della generatrice del cilindro. Si prova che il problema di evoluzione lineare è dato dalla somma diretta di un semigruppo di stretta contrazione ed un semigruppo analitico. Ogni soluzione temporalmente non limitata deriva da autovalori isolati di molteplicità finita, aventi parte reale positiva e parte immaginaria limitata. Si studia anche la struttura dello spettro del generatore del semigruppo, costituito nel lato destro del piano complesso da autovalori di molteplicità finita, e nel lato sinistro di autovalori e da uno spettro essenziale situato su di una retta parallela all’asse immaginario.相似文献
48.
The first direct measurement of the atomic dipole phase in high-order harmonic generation obtained by an interferometric technique in the extreme ultraviolet (XUV) is reported. The effects associated with both the main quantum paths involved in the emission of a given plateau harmonic are investigated and compared with the expectations of the semi-classical model, which offers a very simple physical picture for the understanding of the involved electronic dynamics. 相似文献
49.
Giovanni De Filpo Roberta Cassano Luana Tortora Fiore P. Nicoletta Giuseppe Chidichimo 《Liquid crystals》2008,35(1):45-48
Polymer-dispersed liquid crystal (PDLC) films operating in reverse mode are transparent electro-optical devices, which can be turned into an opaque state by application of a suitable electric field. The effect was investigated of different UV powers, used during the polymerization process, on the electro-optical and morphology properties of PDLCs, working in reverse mode operation. Films were obtained by UV polymerization of mixtures of a low molecular weight nematic liquid crystal and a photopolymerizable liquid crystal monomer, homeotropically aligned by rough conductive surfaces. The electro-optical and morphology properties of samples were related to the polymerization conditions. Samples polymerized by lower UV powers exhibited “polymer ball” morphology and an electro-optical response due to the liquid crystal director reorientation, whereas samples obtained at higher UV powers showed a “Swiss cheese” morphology and an electro-optical response due to dynamic scattering. In addition, we observed by conductivity and IR measurements that UV exposure induces a degradation of the nematic liquid crystal. 相似文献
50.
Stefanelli M Nardis S Tortora L Fronczek FR Smith KM Licoccia S Paolesse R 《Chemical communications (Cambridge, England)》2011,47(14):4255-4257
Mono- and di-substituted β-nitro derivatives have been obtained from the reaction of ttcorrFeCl with sodium nitrite in refluxing DMF. This result is unprecedented for iron corrolates and further evidences the non-innocent character of the corrole ligand. 相似文献