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991.
Alexandru?ConstantinescuEmail author Matteo?Varbaro 《Journal of Algebraic Combinatorics》2011,34(3):375-400
The algebra of basic covers of a graph G, denoted by [`(A)](G)\bar{A}(G), was introduced by Herzog as a suitable quotient of the vertex cover algebra. In this paper we compute the Krull dimension
of [`(A)](G)\bar{A}(G) in terms of the combinatorics of G. As a consequence, we get new upper bounds on the arithmetical rank of monomial ideals of pure codimension 2. Furthermore,
we show that if the graph is bipartite, then [`(A)](G)\bar{A}(G) is a homogeneous algebra with straightening laws, and thus it is Koszul. Finally, we characterize the Cohen–Macaulay property
and the Castelnuovo–Mumford regularity of the edge ideal of a certain class of graphs. 相似文献
992.
Cingolani R. Rinaldi R. Giugno P. V. De Vittorio M. Lomascolo M. Di Dio M. Marti U. Reinhart F. K. 《Il Nuovo Cimento D》1995,17(11):1219-1228
Il Nuovo Cimento D - We present a comprehensive discussion of the excitonic properties of V-shaped GaAs and InGaAs quantum wires grown on patterned substrates. Systematic linear and non-linear... 相似文献
993.
X-ray absorption is the standard method to probe the unoccupied density of states at a given edge. Here we show that polarized resonant inelastic x-ray scattering in La2CuO4 at the Cu L edge is extremely sensitive to the environment of the Cu atom and the fine structure in the Cu 4p density of states. Combined ab initio and many-body cluster calculations, used for the first time in such a context, show remarkable agreement with experiment. In particular, we identify a nonlocal effect, namely, a transition to off-site Cu 3d states. 相似文献
994.
Osmane Camara Anamul H. Mir Krzysztof Dzieciol Graeme Greaves Shibabrata Basak Hans Kungl Matteo Bosi Luca Seravalli Steve E. Donnelly Rüdiger A. Eichel Jonathan A. Hinks 《Particle & Particle Systems Characterization》2021,38(12):2100154
Once nanomaterials have been synthesized, inducing further structural modifications is challenging. However, being able to do so in a controlled manner is crucial. In this context, germanium nanowires are irradiated in situ within a transmission electron microscope (TEM) by a 300 keV xenon ion beam at temperatures ranging from room temperature (RT) to 500 °C. The ion irradiation is performed in situ and the evolution of nanowires during irradiation is monitored. At 300 °C and below, where the temperature is low enough to allow amorphization, the ion beam causes the formation of nanostructures within the nanowires. Formation of nanopores and swelling of nanowires is observed for a very low fluence of 2.2 × 1014 and up to 4.2 × 1015 ions cm−2. At higher fluences, the thickness of the nanowires decreases, the nanowires lose their wire-like cylindrical shape and the nanostructuring caused by the ion beam becomes more complex. The nanostructures are observed to be stable upon crystallization when the nanowires are annealed at 530 °C. Furthermore, in situ imaging allows the growth of nanopores during irradiation to be followed at RT and at 300 °C providing valuable insights into the mechanism responsible for the nanostructuring. 相似文献
995.
996.
The chemical activity of supported metal nanoclusters is enhanced by electronic charging induced by the interaction with surface defects. We use density functional theory plane wave calculations to show that charging of metal atoms with high electron affinity like Au is possible also in the absence of defects by atom deposition on ultrathin MgO films (1 to 3 layers) grown on Mo(100). The Au 6s level falls below the Fermi level of Mo, leading to electron transfer from Mo to Au by direct tunneling through the insulating MgO film. The effect is not observed for Pd, whose 5s empty level falls just above the Fermi level of Mo, or for thicker MgO films. 相似文献
997.
The presence of boron atoms has made carboranes, C(2)B(10)H(12), attractive candidates for boron neutron capture therapy. Because of their chemistry and possible conjugation with proteins, they can also be used to enhance interactions between pharmaceuticals and their targets and to increase the in vivo stability and bioavailability of compounds that are normally metabolized rapidly. Carboranes are isosteric to a rotating phenyl group, which they can substitute successfully in biologically active systems. A reverse ligand-protein docking approach was used in this work to identify binding proteins for carboranes. The screening was carried out on the drug target database PDTD that contains 1207 entries covering 841 known potential drug targets with structures taken from the Protein Data Bank. First, for validation, the protocol was applied to three crystal structures of proteins in which carborane derivatives are present. Then, the model was applied to systems for which the protein structure is available, but the binding site of carborane has not been reported. These systems were used for further validation of the protocol, while simultaneously providing new insight into the interactions between cage and protein. Finally, the screening was carried out on the database to reveal potential carborane binding targets of interest for biological and pharmacological activity. Carboranes are predicted to bind well to protease and metalloprotease enzymes. Other carborane pharmaceutical targets are also discussed, together with possible protein carriers. 相似文献
998.
Matteo Lusardi Aldo Profumo Chiara Rotolo Erika Iervasi Camillo Rosano Andrea Spallarossa Marco Ponassi 《Molecules (Basel, Switzerland)》2022,27(18)
A small library of highly functionalized phenylaminopyrazoles, bearing different substituents at position 1, 3, and 4 of the pyrazole ring, was prepared by the one-pot condensation of active methylene reagents, phenylisothiocyanate, and substituted hydrazine (namely, methyl- and benzyl-hydrazine). The identified reaction conditions proved to be versatile and efficient. Furthermore, the evaluation of alternative stepwise protocols affected the chemo- and regio-selectivity outcome of the one-pot procedure. The chemical identities of two N-methyl pyrazole isomers, selected as prototypes of the whole series, were unambiguously identified by means of NMR and mass spectrometry studies. Additionally, semiempirical calculations provided a structural rationale for the different chromatographic behavior of the two isomers. The prepared tetra-substituted phenylaminopyrazoles were tested in cell-based assays on a panel of cancer and normal cell lines. The tested compounds did not show any cytotoxic effect on the selected cell lines, thus supporting their pharmaceutical potentials. 相似文献
999.
The hydrolytic behavior of antimonic acid, Sb(OH)5o, was experimentally investigated, at fixed temperatures within the range 10–40 °C, by both titration of dilute Na-antimonate
solutions with HClO4 and single-point pH measurements of diluted Sb(OH)5o solutions. The thermodynamic constants, K
a, for the reaction:
were derived at different controlled temperatures, based on pH measurements, applying suitable mass and electrical balances
and correcting the concentrations of ionic species for medium effects. From the resulting log 10
K
a values, those of the corresponding isocoulombic equilibrium reaction:
were computed and used to derive its thermodynamic properties. These were finally combined with the corresponding thermodynamic
properties of the water association reaction, to obtain robust estimations of ΔG
ro, ΔS
ro and ΔH
ro for the ionogenic reaction. These are the first thermodynamic data at temperatures different from 25 °C for the ionization
reaction of Sb(OH)5o. The results of the present work confirm that Sb(OH)5o is a moderately weak and monoprotic acid with a pK
a of 2.848 at 25 °C. 相似文献
1000.
Giorgio Brida Maria Bondani Ivo P. Degiovanni Marco Genovese Matteo G. A. Paris Ivano Ruo Berchera Valentina Schettini 《Foundations of Physics》2011,41(3):305-316
With the purpose of introducing a useful tool for researches concerning foundations of quantum mechanics and applications
to quantum technologies, here we address three quantumness quantifiers for bipartite optical systems: one is based on sub-shot-noise
correlations, one is related to antibunching and one springs from entanglement determination. The specific cases of parametric
downconversion seeded by thermal, coherent and squeezed states are discussed in detail. 相似文献