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821.
F. Belletti A. Cruz L. A. Fernandez A. Gordillo-Guerrero M. Guidetti A. Maiorano F. Mantovani E. Marinari V. Martin-Mayor J. Monforte A. Mu?oz?Sudupe D. Navarro G. Parisi S. Perez-Gaviro J. J. Ruiz-Lorenzo S. F. Schifano D. Sciretti A. Tarancon R. Tripiccione D. Yllanes 《Journal of statistical physics》2009,135(5-6):1121-1158
Using the special-purpose computer Janus, we follow the nonequilibrium dynamics of the Ising spin glass in three dimensions for eleven orders of magnitude. The use of integral estimators for the coherence and correlation lengths allows us to study dynamic heterogeneities and the presence of a replicon mode and to obtain safe bounds on the Edwards-Anderson order parameter below the critical temperature. We obtain good agreement with experimental determinations of the temperature-dependent decay exponents for the thermoremanent magnetization. This magnitude is observed to scale with the much harder to measure coherence length, a potentially useful result for experimentalists. The exponents for energy relaxation display a linear dependence on temperature and reasonable extrapolations to the critical point. We conclude examining the time growth of the coherence length, with a comparison of critical and activated dynamics. 相似文献
822.
Carla Cruz Vânia Calisto Rita Delgado Prof. Vítor Félix Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(13):3277-3289
Three novel large polyazamacrocycles containing two 1,10‐phenanthroline units connected by different polyamine spacers have been synthesised and their protonated forms used as receptors for several aromatic carboxylate anions. The receptors bind to the anions in a 1:1 stoichiometry and exhibit remarkable binding selectivity (see figure). Analysis shows that molecular recognition is governed by π–π stacking interactions and multiple N? H???O?C hydrogen bonds.
823.
Erika A. Olson 《Journal of Differential Equations》2009,246(10):4154-2063
We show that the Cauchy problem for a higher order modification of the Camassa-Holm equation is locally well posed for initial data in the Sobolev space Hs(R) for s>s′, where 1/4?s′<1/2 and the value of s′ depends on the order of equation. Employing harmonic analysis methods we derive the corresponding bilinear estimate and then use a contraction mapping argument to prove existence and uniqueness of solutions. 相似文献
824.
Araceli Peña-Alvarez Erika Ramírez-MayaLuís Ángel Alvarado-Suárez 《Journal of chromatography. A》2009,1216(14):2843-2847
A simple method for the analysis of capsaicin and dihydrocapsaicin in peppers and pepper sauces by solid phase microextraction–gas chromatography–mass spectrometry has been developed. A novel device was designed for direct extraction solid phase microextraction in order to avoid damage to the fiber. The analysis was performed without derivatization for the gas chromatography–mass spectrometry analysis. Selection fiber, extraction temperature, extraction time and pH, were optimized. The method was linear in the range 0.109–1.323 μg/mL for capsaicin and 0.107–1.713 μg/mL for dihydrocapsaicin with correlation coefficient up to r = 0.9970 for both capsaicinoids. The precision of the method was less than 10%. The method was applied to the analysis of 11 varieties of peppers and four pepper sauces. A broad range of capsaicin (55.0–25 459 μg/g) and dihydrocapsaicin (93–1 130 μg/g) was found in the pepper and pepper sauces samples (4.3–717.3 and 1.0–134.8 μg/g), respectively. 相似文献
825.
Erika Ohta Watanabe Ekaterina Popova Everson Alves Miranda Gerd Maurer Pedro de Alcântara Pessôa Filho 《Fluid Phase Equilibria》2009
The salt-induced precipitation of lysozyme from aqueous solutions was studied through precipitation assays in which the equilibrium compositions of the coexisting phases were determined. Lysozyme precipitation experiments were carried out at 5, 15 and 25 °C and pH 7.0 with ammonium sulfate, sodium sulfate and sodium chloride as precipitating agents. In these experiments a complete separation of the coexisting phases (liquid and solid) could not be achieved. Nevertheless it was possible to determine the composition of the precipitate. The enzymatic activity of lysozyme in the supernatant phase as well as in the precipitate phase was also determined. The activity balance suggests that there is a relationship between the composition of the true precipitate and the total activity recovery. 相似文献
826.
Endohedral adsorption properties of ethylene and ethane onto single-walled carbon nanotubes were investigated using a united
atom (2CLJQ) and a fully atomistic (AA-OPLS) force fields, by Grand Canonical Monte Carlo and Molecular Dynamics techniques.
Pure fluids were studied at room temperature, T=300 K, and in the pressure ranges 4×10−4<p<47.1 bar (C2H4) and 4×10−4<p<37.9 bar (C2H6). In the low pressure region, isotherms differ quantitatively depending on the intermolecular potential used, but show the
same qualitative features. Both potentials predict that ethane is preferentially adsorbed at low pressures, and the opposite
behavior was observed at high loadings. Isosteric heats of adsorption and estimates of low pressure Henry’s constants, confirmed
that ethane adsorption is the thermodynamically favored process at low pressures. Binary mixtures of C2H4/C2H6 were studied under several (p,T) conditions and the corresponding selectivities towards ethane, S, were evaluated. Small values of S<4 were found in all cases studied. Nanotube geometry plays a minor role on the adsorption properties, which seem to be driven
at lower pressures primarily by the larger affinity of the alkane towards the carbon surface and at higher pressures by molecular
volume and packing effects. The fact that the selectivity towards ethane is similar to that found earlier on carbon slit pores
and larger diameter nanotubes points to the fact that the peculiar 1-D geometry of the nanotubes provides no particular incentive
for the adsorption of either species. 相似文献
827.
A mild, convenient coupling of aliphatic aldehydes and unactivated alkyl bromides has been developed. The catalytic system features the use of a common Ni(ii) precatalyst and a readily available bioxazoline ligand and affords silyl-protected secondary alcohols. The reaction is operationally simple, utilizing Mn as a stoichiometric reductant, and tolerates a wide range of functional groups. The use of 1,5-hexadiene as an additive is an important reaction parameter that provides significant benefits in yield optimizations. Initial mechanistic experiments support a mechanism featuring an alpha-silyloxy Ni species that undergoes formal oxidative addition to the alkyl bromide via a reductive cross-coupling pathway.Aliphatic aldehydes and alkyl bromides are reductively coupled using nickel catalysis. A BiOX ligand and 1,5-hexadiene paired with a silyl chloride and Mn as the terminal reductant are important features of the process. 相似文献
828.
Norman Cruz Samuel Lepe Francisco Pe?a Joel Saavedra 《The European Physical Journal C - Particles and Fields》2010,65(1-2):289-293
We extend the classical Damour–Ruffini method and discuss Hawking radiation spectrum of high-dimensional rotating black hole using Tortoise coordinate transformation defined by taking the reaction of the radiation to the spacetime into consideration. Under the condition that the energy and angular momentum are conservative, taking self-gravitation action into account, we derive Hawking radiation spectrums which satisfy unitary principle in quantum mechanics. It is shown that the process that the black hole radiates particles with energy ω is a continuous tunneling process. We provide a theoretical basis for further studying the physical mechanism of black-hole radiation. 相似文献
829.
M. Bello-Jiménez C. Cuadrado-Laborde A. Diez J. L. Cruz M. V. Andrés 《Applied physics. B, Lasers and optics》2011,105(2):269-276
We report an experimental study of an actively mode-locked fiber ring laser based on the development of an efficient in-fiber
amplitude modulator. Intermodal coupling induced by standing flexural acoustic waves permits the implementation of broad bandwidth
(1.5 nm), high modulation depth (72%), low-insertion-loss (0.75 dB), in-fiber amplitude modulators, operating in the MHz frequency
range. The experimental characterization of the laser as a function of the radio frequency voltage that controls the modulator,
the length of the active fiber, and the optical bandwidth of an intracavity filter implemented with a fiber Bragg grating
has led to an improved performance of the Erbium-doped fiber laser: optical pulses of 34-ps temporal width, 1.4-W peak power,
and 4.75-MHz repetition rate. 相似文献
830.
Raphael M. Jay Sebastian Eckert Vinícius VazdaCruz Mattis Fondell Rolf Mitzner Alexander Fhlisch 《Angewandte Chemie (International ed. in English)》2019,58(31):10742-10746
Covalency is found to even out charge separation after photo‐oxidation of the metal center in the metal‐to‐ligand charge‐transfer state of an iron photosensitizer. The σ‐donation ability of the ligands compensates for the loss of iron 3d electronic charge, thereby upholding the initial metal charge density and preserving the local noble‐gas configuration. These findings are enabled through element‐specific and orbital‐selective time‐resolved X‐ray absorption spectroscopy at the iron L‐edge. Thus, valence orbital populations around the central metal are directly accessible. In conjunction with density functional theory we conclude that the picture of a localized charge‐separation is inadequate. However, the unpaired spin density provides a suitable representation of the electron–hole pair associated with the electron‐transfer process. 相似文献