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431.
Development and validation of a liquid chromatography with mass spectrometry method to determine resveratrol and piceid isomers in beeswax 下载免费PDF全文
Ana M. Ares Yolanda González María J. Nozal José L. Bernal Mariano Higes José Bernal 《Journal of separation science》2015,38(2):197-204
This paper represents the first report of a liquid chromatography coupled to electrospray ionization mass spectrometry method for simultaneously analyzing resveratrol and piceid isomers (cis and trans) in beeswax. An efficient extraction procedure has been proposed (average analyte recoveries were between 89 and 95%); this involved a solid–liquid extraction using a mixture of ethanol and water (80:20, v/v) and a concentration step in a rotary evaporator. The separation of all the compounds was achieved using a C18 column and a mobile phase composed of ammonium formate 0.03 M in water and acetonitrile in gradient elution mode at a flow rate of 1 mL/min. The method was fully validated in terms of selectivity, limits of detection and quantification, linearity, precision, and accuracy. The limits of detection and quantification ranged from 1.0 to 1.7 and 3.5 to 5.5 μg/kg, respectively. Finally, the proposed method was applied to analyze beeswax samples collected from experimental and organic apiaries. 相似文献
432.
Gyuzel Yu. Mitronova Dr. Vladimir N. Belov Dr. Mariano L. Bossi Dr. Christian A. Wurm Dr. Lars Meyer Dr. Rebecca Medda Dr. Gael Moneron Dr. Stefan Bretschneider Dr. Christian Eggeling Dr. Stefan Jakobs Dr. Stefan W. Hell Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(15):4407-4407
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434.
Paolo Maria Mariano Paolo Paoletti 《Mathematical Methods in the Applied Sciences》2009,32(9):1041-1067
The mechanics of complex bodies with memory effects is discussed in linearized setting. The attention is focused on the characterization of free energies in terms of minimum work and maximum recoverable work in the bulk and along a discontinuity surface endowed with its own surface energy, a surface within the body. To this aim, use is made of techniques proposed by Del Piero. Consequences of the Clausius–Duhem inequality are investigated for complex bodies with instantaneous linear elastic response. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
435.
Vladimir N. Belov Dr. Mariano L. Bossi Dr. Jonas Fölling Dr. Vadim P. Boyarskiy Dr. Stefan W. Hell Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(41):10762-10776
The design, synthesis, and evaluation of new rhodamine spiroamides are described. These molecules have applications in optical nanoscopy based on random switching of the fluorescent single molecules. The new markers may be used in (co)localization studies of various objects and their (mutual) positions and shape can be determined with a precision of a few tens of nanometers. Multicolor staining, good photoactivation, a large number of emitted photons, and selective chemical binding with amino or thiol groups were achieved due to the presence of various functional groups on the rhodamine spiroamides. Rigidized sulfonated xanthene fragment fused with six‐membered rings, N,N′‐bis(2,2,2‐trifluoroethyl) groups, and a combination of additional double bonds and sulfonic acid groups with simple aliphatic spiroamide residue provide multicolor properties and improve performance of the rhodamine spiroamides in photoactivation and bioconjugation reactions. Having both essential parts of the photoswitchable assembly—the switching and the fluorescent (reporter) groups—combined in one chemical entity make this approach attractive for further development. A series of rhodamine spiroamides is presented along with characterizations of their most relevant properties for application as fluorescent probes in single‐molecule switching and localization microscopy. Optical images with resolutions on the nanometer scale illustrate the potential of the labels in the colocalization of biological objects and the two‐photon activation technique with optical sectioning. 相似文献
436.
Let ?? be a smooth, compact, oriented Riemannian manifold without boundary. Weak limits of graphs of smooth maps uk:Bn → ?? with an equibounded Dirichlet integral give rise to elements of the space cart2,1 (Bn × ??). Assume that ?? is 1‐connected and that its 2‐homology group has no torsion. In any dimension n we prove that every element T in cart2,1 (Bn × ??) with no singular vertical part can be approximated weakly in the sense of currents by a sequence of graphs of smooth maps uk:Bn → ?? with Dirichlet energies converging to the energy of T. © 2006 Wiley Periodicals, Inc. 相似文献
437.
Mariano A. Ruiz Demetrio Stojanoff 《Journal of Mathematical Analysis and Applications》2008,343(1):366-378
We study the relationship among operators, orthonormal basis of subspaces and frames of subspaces (also called fusion frames) for a separable Hilbert space H. We get sufficient conditions on an orthonormal basis of subspaces E={Ei}i∈I of a Hilbert space K and a surjective T∈L(K,H) in order that {T(Ei)}i∈I is a frame of subspaces with respect to a computable sequence of weights. We also obtain generalizations of results in [J.A. Antezana, G. Corach, M. Ruiz, D. Stojanoff, Oblique projections and frames, Proc. Amer. Math. Soc. 134 (2006) 1031-1037], which relate frames of subspaces (including the computation of their weights) and oblique projections. The notion of refinement of a fusion frame is defined and used to obtain results about the excess of such frames. We study the set of admissible weights for a generating sequence of subspaces. Several examples are given. 相似文献
438.
Francisco Ruiz Mariano Luque Francisca Miguel María del Mar Muñoz 《European Journal of Operational Research》2008
The success of the reference point scheme within interactive techniques for multiobjective programming problems is unquestionable. However, so far, the different achievement scalarizing functions are, more or less, extensions of the Tchebychev distance. The reason for this is the ability of this function to determine efficient solutions and to support every efficient solution of the problem. For the same reasons, no additive scheme has yet been used in reference point-based interactive methods. In this paper, an additive achievement scalarizing function is proposed. Theoretical results prove that this function supports every efficient solution, and conditions are given under which the efficiency of each solution is guaranteed. Some examples and computational tests show the different behaviours of the Tchebychev and additive approaches, and an additive reference point interactive algorithm is proposed. 相似文献
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440.
Absolute rate coefficients for the gas‐phase reactions of CF2?CFCl and (E/Z)‐CFCl?CFCl with O(3P) atoms have been measured at 298 K using a discharge flow tube coupled to a chemiluminescence detection system. The observed rate constant values are (4.5 ± 0.4) × 10?13 and (1.5 ± 0.3) × 10?13 cm3 molecule?1 s?1, respectively. The experiments were carried out under pseudo‐first‐order conditions with [O(3P)]0 ? [alkene]0. These results are compared to those of O atom reactions with other chlorine‐ and fluorine‐substituted ethenes. Different factors that affect the rate of addition to the double bond are considered. The O(3P)/chloroethenes reactions do not obey the reactivity trend with the ionization potential, as is the case in the alkene and methyl‐substituted alkene reactions. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36:525–533, 2004 相似文献