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61.
James V. Crivello Ricardo Acosta Ortiz 《Journal of polymer science. Part A, Polymer chemistry》2001,39(14):2385-2395
The synthesis of a series of novel cationically photopolymerizable epoxide monomers bearing benzyl, allyl, and propargyl acetal and ether groups that can stabilize free radicals was carried out. These monomers display enhanced reactivity in cationic photopolymerization in the presence of certain onium salt photoinitiators. Specifically, this article describes schemes for the synthesis of cycloaliphatic epoxy monomers bearing free‐radical stabilizing groups. During UV irradiation of an onium salt cationic photoinitiator, the aryl radicals that are generated abstract labile protons present in such monomers to generate the corresponding carbon‐centered radicals. Subsequently, these radicals can interact with the onium salt by a redox mechanism to induce the decomposition of these salts. The overall result is that additional cationic species are generated by this mechanism that increase the rate and extent of the cationic ring‐opening polymerization of the epoxide monomer. An investigation of the photopolymerizations of the monomers prepared during this work was carried out using Fourier transform real‐time infrared spectroscopy, and conclusions were drawn with respect to the relationship between their structures and reactivity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2385–2395, 2001 相似文献
62.
Acosta RH Blümler P Han S Appelt S Häsing FW Schmiedeskamp J Heil W Spiess HW 《Magnetic resonance imaging》2004,22(8):1077-1083
With the use of hyperpolarized gases, a great number of experiments have been carried out in order to improve the diagnostics of the lung, both from a structural and a functional point of view. 3He is best suited for structural studies, whereas 129Xe gives more detailed information about the functionality of the lung because it enters the bloodstream. In this work, we propose the use of a gas mixture to perform consecutive analysis of lung structure and functionality upon the delivery of a single bolus of gas. We show images of a helium-xenon gas mixture in the presence of a small amount of liquid toluene in order to demonstrate how both nuclei can be detected independently, extracting the spectroscopic information provided by the 129Xe spectra and obtaining an image with high sensitivity for 3He. A second experiment performed on a dissected mouse lung was used to demonstrate how the mixture of gases can enhance sensitivity in the larger airways of the lung. 相似文献
63.
In this article a technique to achieve synchronization in spatially extended systems is introduced. The basic idea behind this method is to map a system of partial differential equations (PDEs) into a high-dimensional space where the representation of this PDE is an ordinary differential equation. By using semi-group theory, we are able to find conditions that ensure the synchronization of two systems of non-identical reaction–diffusion equations with a master–slave coupling. 相似文献
64.
David Tejedor Dr. Sara López‐Tosco Fabio Cruz‐Acosta Gabriela Méndez‐Abt Fernando García‐Tellado Dr. 《Angewandte Chemie (International ed. in English)》2009,48(12):2090-2098
Three that matter : Metal acetylides from alkyl propiolates allow C3 homologations with transference of their versatile reactivity profile to products that can then react without further elaboration. Metal‐free acetylides, which are generated by the action of a good nucleophile on the alkyl propiolate, react with suitable electrophiles through different domino reactions to generate skeletal diversity.
65.
Gracia C Isidro-Llobet A Cruz LJ Acosta GA Alvarez M Cuevas C Giralt E Albericio F 《The Journal of organic chemistry》2006,71(19):7196-7204
Kahalalide compounds are peptides that are isolated from a Hawaiian herbivorous marine species of mollusc, Elysia rufescens, and its diet, the green alga Bryopsis sp. Kahalalide F and its synthetic analogues are the most promising compounds of the Kahalalide family because they show antitumoral activity. Linear solid-phase syntheses of Kahalalide F have been reported. Here we describe several new improved synthetic routes based on convergent approaches with distinct orthogonal protection schemes for the preparation of Kahaladide analogues. These strategies allow a better control and characterization of the intermediates because more reactions are performed in solution. 相似文献
66.
Szekeres E Acosta E Sabatini DA Harwell JH 《Journal of colloid and interface science》2006,294(1):222-233
Polar/amphiphilic oils, called lipophilic linkers, are sometimes added to oil-water-ionic surfactant microemulsions in order to increase the solubilization of hydrophobic oils. The solubilization increase has been well documented for a number of systems. However, mathematical models to calculate the solubilization increase have been proposed only for optimum microemulsions (i.e., middle phase microemulsions solubilizing equal volumes of oil and water). In this paper we propose a model, which predicts solubilization enhancement for non-optimum microemulsion systems as well. The model is an extension of the net-average curvature model of microemulsion. The net-average curvature model is combined with a surface activity model to account for the increased palisade layer solubilization due to the presence of the polar/amphiphilic oil component. New non-linear mixing rules are also incorporated to account for the optimum salinity and the characteristic length variation of the anionic surfactant microemulsion as a function of the lipophilic linker concentration. The model predicts the effect of the lipophilic linker and the electrolyte concentration on the oil solubilization in accordance with the experimental results. 相似文献
67.
Abulencia A Acosta D Adelman J Affolder T Akimoto T Albrow MG Ambrose D Amerio S Amidei D Anastassov A Anikeev K Annovi A Antos J Aoki M Apollinari G Arguin JF Arisawa T Artikov A Ashmanskas W Attal A Azfar F Azzi-Bacchetta P Azzurri P Bacchetta N Bachacou H Badgett W Barbaro-Galtieri A Barnes VE Barnett BA Baroiant S Bartsch V Bauer G Bedeschi F Behari S Belforte S Bellettini G Bellinger J Belloni A Ben Haim E Benjamin D Beretvas A Beringer J Berry T Bhatti A Binkley M Bisello D Blair RE 《Physical review letters》2006,97(1):012002
We present a measurement of the Bc+ meson lifetime in the decay mode Bc+ --> J/Psie+nue using the Collider Detector at Fermilab II detector at the Fermilab Tevatron Collider. From a sample of about of 360 pb(-1) of pp collisions at square root of s = 1.96 TeV, we reconstruct J/Psie+ pairs with invariant mass in the kinematically allowed range 4< M(J/Psie) < 6 GeV/c2. A fit to the decay-length distribution of 238 signal events yields a measured Bc+ meson lifetime of 0.463(-0.065)(+0.073)(stat) +/- 0.036(syst) ps. 相似文献
68.
María D. Acosta Mieczysław Mastyło Maryam Soleimani-Mourchehkhorti 《Journal of Functional Analysis》2018,274(9):2673-2699
We study the Bishop–Phelps–Bollobás property for operators between Banach spaces. Sufficient conditions are given for generalized direct sums of Banach spaces with respect to a uniformly monotone Banach sequence lattice to have the approximate hyperplane series property. This result implies that Bishop–Phelps–Bollobás theorem holds for operators from into such direct sums of Banach spaces. We also show that the direct sum of two spaces with the approximate hyperplane series property has such property whenever the norm of the direct sum is absolute. 相似文献
69.
María D. Acosta 《Israel Journal of Mathematics》1993,81(3):273-280
First we show that every real Banach space satisfying a certain property, calledβ (used by Lindenstrauss and Partington) verifies the denseness of the numerical radius attaining operators. Using this result
and a renorming theorem by Partington we conclude that every Banach space is isomorphic to a new one satisfying the denseness
of the numerical radius attaining operators. 相似文献
70.
Edgar J. Acosta 《Colloids and surfaces. A, Physicochemical and engineering aspects》2008,320(1-3):193-204
The net–average curvature (NAC) model (Langmuir, 19, 186, 2003) is a simple, yet powerful, equation of state to fit and predict the phase behavior of microemulsions (μEs) formulated with ionic surfactants. However, its use for nonionic surfactants systems has not been evaluated until now. The objective of this work is to use the NAC equation of state to model the phase behavior of μEs formulated with pure alcohol ethoxylate (CiEj) and commercial nonylphenol ethoxylate (NPEj) surfactants with a range of alkanes (Cn). The NAC model requires three basic parameters: the characteristic curvature of the nonionic surfactant (Ccn), the characteristic length (ξ), and the scaling length parameter (L). The first part of this contribution presents a brief review of the NAC model and other thermodynamic models of μEs. Later, five example applications of the NAC model are presented and discussed: (I) fit/prediction of phase inversion temperature (PIT) values, (II) prediction of phase transition temperatures and characteristic lengths, (III) fit/prediction of interfacial tensions, (IV) prediction of “fish” phase diagrams, and (V) prediction of the composition of bicontinuous systems. The NAC model was able to fit the phase behavior observed in all the experimental scenarios, and predict within 30% the value of phase volumes and transition temperatures for CiEj systems. The largest deviations can be attributed to a poor estimation of ξ obtained through empirical correlations. It was also noted that for commercial NPEj surfactants, the NAC model can also fit and predict the phase behavior of these systems, only that more complex empirical correlations are needed for ξ and Ccn due to the partition of different surfactant n-mers into the excess oil and aqueous phases. In all cases, a good agreement was found when the length parameter (L) was estimated as 1.4 times the extended length of the surfactant tail. 相似文献