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41.
We study the probability distribution of the pseudocritical temperature in a mean-field and in a short-range spin-glass model: the Sherrington-Kirkpatrick and the Edwards-Anderson (EA) model. In both cases, we put in evidence the underlying connection between the fluctuations of the pseudocritical point and the extreme value statistics of random variables. For the Sherrington-Kirkpatrick model, both with Gaussian and binary couplings, the distribution of the pseudocritical temperature is found to be the Tracy-Widom distribution. For the EA model, the distribution is found to be the Gumbel distribution. Being the EA model representative of uniaxial magnetic materials with quenched disorder like Fe(0.5)Mn)0.5)TiO(3) or Eu(0.5)Ba(0.5)MnO(3), its pseudocritical point distribution should be a priori experimentally accessible. 相似文献
42.
Elia Tfouni Fabio Gorzoni Doro Anderson Jesus Gomes Roberto Santana da Silva Gustavo Metzker Patricia Graça Zanichelli Benini Douglas Wagner Franco 《Coordination chemistry reviews》2010,254(3-4):355-371
Methodologies for the immobilization and characterization of ruthenium complexes into/onto functionalized silica gel, zeolites, polymers, dendrimers, sol–gel, nano and microparticles are described. The corresponding spectroscopic, electrochemical, and photochemical properties as well as chemical reactivities are used for their characterization and study. Comparison between the reactivities of immobilized and in solution species is presented. Some biological applications are also described. 相似文献
43.
Graph theoretic relaxations are used to design tree search algorithms for set-covering and set-partitioning problems. In this paper two assignment relaxations for the set-covering and set-partitioning problems are presented and a tree search method is developed which makes use of these relaxations. Computational experience of processing a collection of test problems is reported. 相似文献
44.
45.
Alessandro Ciattoni Rino Marinelli Carlo Rizza Elia Palange 《Applied physics. B, Lasers and optics》2013,110(1):23-26
We consider a mixture of metal-coated quantum dots dispersed in a polymer matrix and, using a modified version of the standard Maxwell-Garnett mixing rule, we prove that the mixture parameters (particles radius, quantum dots gain, etc.) can be chosen so that the effective medium permittivity has an absolute value very close to zero in the near-infrared, i.e. $|{\rm Re}(\epsilon)| \ll 1$ and $|{\rm Im}(\epsilon)| \ll 1$ at the same near-infrared wavelength. Resorting to full-wave simulations, we investigate the accuracy of the effective medium predictions and we relate their discrepancy with rigorous numerical results to the fact that $|\epsilon| \ll 1$ is a critical requirement. We show that a simple method for reducing this discrepancy, and hence for achieving a prescribed and very small value of $|\epsilon|, $ consists in a subsequent fine-tuning of the nanoparticles volume filling fraction. 相似文献
46.
María del Carmen Barral Rodrigo González-Prieto Santiago Herrero Reyes Jiménez-Aparicio José Luis Priego Elia del Carmen Royer María Rosario Torres Francisco Alejandro Urbanos Felix Zamora 《Journal of Cluster Science》2008,19(1):219-230
Two new complexes, based on the unit Ru2Cl(μ-O2CC4H4N)4 (1) (O2CC4H4N = pyrrole-2-carboxylate), Ru2Cl(μ-O2CC4H4N)4(H2O)·4H2O [1(H
2
O)·4H
2
O], and Ru2Cl(μ-O2CC4H4N)4(Me2CO) [1(Me
2
CO)], are synthesized and structurally characterized. The physical properties of these complexes are studied and compared with
those previously reported for Ru2Cl(μ-O2CC4H4N)4(thf)·thf·H2O [1(thf)·thf·H
2
O]. The nature of the solvent molecule bonded to the axial position of the dimetallic unit determines the supramolecular interactions
leading to different arrangements in the solid state. The presence of NH groups in the pyrrolic rings favours the existence
of hydrogen bond interactions that are present in the three complexes. In addition, complex 1(Me
2
CO) shows π–π stacking interactions through pyrrolic rings of different dimetallic units.
Dedicated to the memory of Prof. F. Albert Cotton. 相似文献
47.
Giuseppina Castronuovo Vittorio Elia Filomena Velleca 《Journal of solution chemistry》1996,25(1):51-59
Enthalpies of dilution of binary and ternary aqueous solutions containing L-and D-proline, cis-L- and cis-D-4-hydroxy proline, trans-L-4-hydroxy proline, have been determined by flow calorimetry at 25°C. Pairwise self-and cross-interaction coefficients of the virial expansion of the excess enthalpies were evaluated. They are positive for solutions of unsubstituted prolines. On the contrary, upon the introduction of a hydroxy group, they become negative, reaching the largest value for the cis-L-lcis-D-4-hydroxy proline system. The results are interpreted in terms of preferential configurations, stabilized by interactions between the hydrophilic groups. 相似文献
48.
Guido Barone Giuseppina Castronuovo Pompea Del Vecchio Vittorio Elia Maria Teresa Tosto 《Journal of solution chemistry》1988,17(10):925-936
The excess enthalpies of ternary aqueous solutions of biuret with four aliphatic alcohols or four isomeric pentoses have been determined by flow microcalorimetry at 25°C. The coefficients of the virial expansion of the excess enthalpies have been evaluated and compared with those already reported for urea and thiourea with the same alcohols and pentoses used here. For biuret-alcohol systems, the cross coefficients are positive and depend on the length and branching of the alkyl chain of the alcohols. On the contrary, they are negative for biuret-pentose systems. Hence, biuret, as urea and thioura, is able to differentiate the behavior of families of solutes characterized by the same functional groups. The results are interpreted in terms of the relative stabilities of the hydration cospheres of predominantly hydrophobic or predominantly hydrophilic cosolutes. However, hypotheses about the hydration cospheres of the saccharides, which are more complex than those used previously, seem to be necessary to rationalize their complete behavior in water. 相似文献
49.
50.
Matthew L. Gettings Michael T. Thoenen Dr. Edward F. C. Byrd Dr. Jesse J. Sabatini Dr. Matthias Zeller Prof. Dr. Davin G. Piercey 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(64):14530-14535
This work reports the first compound containing both a tetrazole and an azasydnone ring, a unique energetic material. Several energetic salts of the tetrazole azasydnone were synthesized and characterized, leading to the creation of new secondary and primary explosives. Molecular structures are confirmed by 1H and 13C NMR, IR spectroscopy, and X-ray crystallographic analysis. The high heats of formation, fast detonation velocities, and straight-forward synthesis of energetic azasydnones should capture the attention of future energetics research. 相似文献