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81.
Aschi M Zazza C Spezia R Bossa C Di Nola A Paci M Amadei A 《Journal of computational chemistry》2004,25(7):974-984
In this article we use the recently developed perturbed matrix method (PMM) to investigate the effect of conformational fluctuations on the electronic properties of heme in Myoglobin. This widely studied biomolecule has been chosen as a benchmark for evaluating the accuracy of PMM in a large and complex system. Using a long, 80-ns, molecular dynamics simulation and unperturbed Configuration Interaction (CISD) calculations in PMM, we reproduced the main spectroscopic features of deoxy-Myoglobin. Moreover, in line with our previous results on a photosensitive protein, this study reveals a clear dynamical coupling between electronic properties and conformational fluctuations, suggesting that this correlation could be a general feature of proteins. 相似文献
82.
Costantino Zazza Luigi Bencivenni Andrea Grandi Massimiliano Aschi 《Journal of Molecular Structure》2004,680(1-3):117-120
In this paper Time-Dependent Density Functional Theory (TD-DFT) with Becke's three-parameter hybrid method using the Lee–Yang–Parr correlation functional (B3LYP) in conjunction with different basis sets is applied to calculate the solvatochromic shift on the lowest singlet transition of formaldehyde in vacuum and in solution. Our results, in excellent agreement with solvent excitation energy shift of acetone in water at 298–300 K (no experimental data on formaldehyde in water are available so far) and with previous high level quantum chemical calculations, help in appreciating the potentialities of the combined DFT/PCM approach on aquo-complexes for the study of structural and spectroscopic properties of molecule in solution. 相似文献
83.
Beltrame P Cadoni E Floris C Gelli G Lai A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(12):2693-2697
The 2-, 3- and 4-amino-pyridine and their protonated forms, obtained by reaction with pyridinium chloride, were investigated by 15N NMR spectroscopy. Exhaustive evidence has been found that the protonation occurs mainly on the annular nitrogen. Protonation of 4-aminopyridine by dehydrohalogenation of 1,1,2,2-tetrachloroethane (TCE) was also studied by 13C NMR spectroscopy, which indicated that the protonation occurs via the formation of adducts. 相似文献
84.
Retsos H Gorodyska G Kiriy A Stamm M Creton C 《Langmuir : the ACS journal of surfaces and colloids》2005,21(17):7722-7725
We investigated the adhesive properties of binary heterogeneous polymer brushes made from end-functionalized polystyrene (PS) and poly(2-vinylpyridine) (P2VP) chains. The molecular organization of the mixed brush could be varied reversibly by exposure to selective solvents for PS (toluene) and for P2VP (acidic water). This exposure results in reversible switching of adhesive and wetting properties. The manner in which the adhesion switching occurs can be tuned by the composition of mixed brushes. However, the outer surface composition could be enriched more effectively in PS after the toluene treatment than in P2VP after the acidic water treatment. As a result, the mixed brush compositions that showed the largest difference in properties between an exposure to toluene and an exposure to water were the P2VP-rich compositions. Adhesive properties, tested against a soft hydrophobic pressure-sensitive adhesive (PSA) using a probe test, always showed smaller differences between solvent treatments than wetting properties with water, suggesting a much higher sensitivity of the hydrophobic/hydrophilic brushes to polar molecules than to nonpolar molecules. 相似文献
85.
Costantino Capozzoli 《Ricerche di matematica》2012,61(2):171-184
Let ?? be a bounded open subset of ${\mathbb{G}}$ , where ${\mathbb{G}}$ is a Carnot group, and let ${u: \Omega \rightarrow \mathbb{R}^d}$ be a vector valued function. We prove a lower semicontinuity result in the weak topology of the horizontal Sobolev space ${W^{1,p}_X(\Omega,\mathbb{R}^d)}$ , with p?>?1, of the integral functional of the calculus of variations of the type $$F(u)=\int\limits_\Omega f(Xu)\,dx$$ where f is a X-quasiconvex function satisfying a non-standard growth conditions and Xu is the horizontal gradient of u. 相似文献
86.
Zazza C Rutigliano M Sanna N Barone V Cacciatore M 《The journal of physical chemistry. A》2012,116(9):1975-1983
The O/β-quartz interaction is described by combining our time-dependent semiclassical approach to atom-molecule/surface scattering with first-principles electronic structure calculations at the DFT (PBE0) level of accuracy. In particular, the O, O(2) interaction potentials with an on-top Si atom and its nearest O atom both localized over three different silica clusters have been calculated as a function of the oxygen-silica approaching distance. The calculated DFT potential energy surface has been used in semiclassical trajectory calculations to investigate the sticking and inelastic reflection of oxygen atoms from a model β-quartz surface. The collisional mechanism, including the role played by the phonon dynamics, is brought to light and accurate sticking probabilities are calculated at five impact energies in the range [0.05-0.8] eV and T(S) = 1000 K. The different catalytic response of β-quartz and β-cristobobalite to the atomic oxygen flux is also discussed and highlighted. 相似文献
87.
Levenius M Conforti M Baronio F Pasiskevicius V Laurell F De Angelis C Gallo K 《Optics letters》2012,37(10):1727-1729
We theoretically and experimentally investigate multistep parametric processes in broadband optical parametric generators (OPGs) based on periodically poled 1 mol. % MgO-doped stoichiometric LiTaO3. We demonstrate that parametric collateral processes may deplete or enhance spectral portions of the OPG output, depending on pump pulse duration. 相似文献
88.
The interpretation of the violation of Bell-Clauser-Horne inequalities is revisited, in relation with the notion of extension of QM predictions to unmeasurable correlations. Such extensions are compatible with QM predictions in many cases, in particular for observables with compatibility relations
described by tree graphs. This implies classical representability of any set of correlations 〈A
i
〉, 〈B〉, 〈A
i
B〉, and the equivalence of the Bell-Clauser-Horne inequalities to a non void intersection between the ranges of values for
the unmeasurable correlation 〈A
1
A
2〉 associated to different choices for B. The same analysis applies to the Hardy model and to the “perfect correlations” discussed by Greenberger, Horne, Shimony
and Zeilinger. In all the cases, the dependence of an unmeasurable correlation on a set of variables allowing for a classical
representation is the only basis for arguments about violations of locality and causality. 相似文献
89.
The use of tetraphosphonic building blocks for the preparation of inorganic-organic zirconium derivatives has led to the formation of novel compounds with a modular structure. This is based on the different connection of polymeric 1D inorganic units covalently connected by organic groups. The different kinds of connections generate two different open-framework structures. These structures have been solved "ab initio" by powder X-ray diffraction data. Very likely, the dimensions of the channels inside these structures may be tuned by the right choice of the interlinking organic group. 相似文献
90.
Francesca Bellezza Antonio Cipiciani Umberto Costantino Fabio Marmottini Maria Anna Quotadamo 《Colloid and polymer science》2006,285(1):19-25
Non-ionic water-in-oil (w/o) microemulsions of pentaoxyethylenenonylphenyl ether (Igepal-CO520)/cyclohexane/water at 25 °C have been used as reaction vessels to obtain zirconium hydrogen phosphate nanoparticles. 相似文献