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71.
Rodríguez Flores J Berzas Nevado JJ Contento Salcedo AM Cabello Díaz MP 《Journal of separation science》2004,27(1-2):33-40
A capillary zone electrophoresis method is proposed for the separation of six of the antidepressants most used for the treatment of mental illness (clomipramine, paroxetine, fluoxetine, citalopram, fluvoxamine, and trazodone). Optimum conditions for their separation were investigated. A background electrolyte solution consisting of 50 mM phosphate buffer adjusted to pH 2.0, hydrodynamic injection, and 25 kV as separation voltage were used. Relative standard deviations (RSD) were <0.38% and <2.93% for migration time and corrected peak area (n = 24), respectively. Detection limits obtained for the six antidepressants ranged from 0.03 to 0.11 mg L(-1). Stability of the solutions, linear concentration range, accuracy, and precision were examined during validation of the method. A ruggedness test of this method was performed using the fractional factorial model of Plackett-Burman, requiring in our case design of a matrix of 15 experiments, in which the influence of seven factors at three different levels was tested on different electrophoretic results: efficiency; resolution; and corrected peak area. Statistical evaluation of electrophoretic results was achieved by Youden and Steiner's method. The described method is rapid, sensitive, and rugged and it was tested for the pharmaceutical formulation analysis, giving recoveries between 95.6 and 99.1% with respect to the nominal content. 相似文献
72.
We prove that each positive operator from a Köthe function-space E() to a Banach lattice F with a narrow majorant is itself narrow provided the norm on F is order continuous. We also prove that every l
2-strictly singular regular operator from L
p[0,1], 1p < , to a Banach lattice F is narrow, provided F has an order continuous norm. 相似文献
73.
Vikram Basava Broc Flores Matthew Giovine Thomas Licisyn Katelyn Walck Walter Boyko 《Journal of carbohydrate chemistry》2013,32(7):389-400
The addition of benzenesulfinic acid to glycals was investigated under various conditions, and optimized yields of the glycosyl phenylsulfone products were obtained in the presence of tin tetrachloride as a catalyst. Double bond shift (Ferrier rearrangement) occurred in all cases except amicetal, which lacks a substituent at the allylic carbon. Glycosylation of benzenesulfinic acid with 1,2-dibromides was carried out using silver triflate as the promoter, and gave sulfinate esters as products by reaction at oxygen rather than at sulfur. The sulfinate esters were obtained as mixtures of stereoisomers at the stereogenic sulfur atom. Trapping of the sulfinates with carboxylate nucleophiles was observed during attempted oxidation with MCPBA. 相似文献
74.
In order to apply variational methods to the action functional for geodesics of a stationary spacetime, some hypotheses, useful to obtain classical Palais-Smale condition, are commonly used: pseudo-coercivity, bounds on certain coefficients of the metric, etc. We prove that these technical assumptions admit a natural interpretation for the conformal structure (causality) of the manifold. As a consequence, any stationary spacetime with a complete timelike Killing vector field and a complete Cauchy hypersurface (thus, globally hyperbolic), is proved to be geodesically connected. 相似文献
75.
L. Calvo Blazquez J. Rodriguez Flores F. Vinagre Jara A. Sanchez Misiego 《Journal of Chemical Sciences》1989,101(5):415-419
The electroanalytical behaviour of orotic acid in cathodic processes has been studied in HClO4, at several pH values in Britton-Robinson buffers, using DPP and CV techniques.
Orotic acid undergoes three cathodic waves over the entire pH range considered. Optimum conditions for determination of orotic
acid using the DPP technique are also studied. 相似文献
76.
A statistical mechanical model is used to analyze literature data regarding the restricted segmental dynamics of a number of crystallized polymers, as observed by means of broadband dielectric spectroscopy. A relationship between well defined physical quantities and the width parameter in the Havriliak–Negami representation of symmetric processes is established. It is found that, for materials crystallized from an isotropic amorphous state, the segmental relaxation process is associated to conformational changes within cooperatively rearranging regions of ~1 nm diameter. In case of chain orientation, the dimension of the rearranging regions along the chain direction increases up to 3–5 nm. It is argued that the average size of the rearranging regions may influence the thickness of the amorphous interlamellar layers in the stacks. It is also found in all cases that, at the end of the crystallization process, the average fluctuation component of the chemical potential within the confined amorphous regions, $\overline{\Delta\mu}A statistical mechanical model is used to analyze literature data regarding the restricted segmental dynamics of a number
of crystallized polymers, as observed by means of broadband dielectric spectroscopy. A relationship between well defined physical
quantities and the width parameter in the Havriliak–Negami representation of symmetric processes is established. It is found
that, for materials crystallized from an isotropic amorphous state, the segmental relaxation process is associated to conformational
changes within cooperatively rearranging regions of ~1 nm diameter. In case of chain orientation, the dimension of the rearranging
regions along the chain direction increases up to 3–5 nm. It is argued that the average size of the rearranging regions may
influence the thickness of the amorphous interlamellar layers in the stacks. It is also found in all cases that, at the end
of the crystallization process, the average fluctuation component of the chemical potential within the confined amorphous
regions, [`(Dm)]\overline{\Delta\mu}, is of the same order of the chemical potential drop Δμ
cryst associated to crystallization from the undercooled, relaxed melt. Except in one among the cases considered, it is found that
[`(Dm)] ? - Dmcryst\overline{\Delta\mu}\approx - \Delta\mu_{\rm cryst}, which is a hint towards the formalization of a thermodynamic criterion for crystallization arrest. 相似文献
77.
Benjamin M. Gray Andrew L. Hector William Levason Gillian Reid Michael Webster Wenjian Zhang Marek Jura 《Polyhedron》2010
The reaction of o-C6H4(AsMe2)2 with VCl4 in anhydrous CCl4 produces orange eight-coordinate [VCl4{o-C6H4(AsMe2)2}2], whilst in CH2Cl2 the product is the brown, six-coordinate [VCl4{o-C6H4(AsMe2)2}]. In dilute CH2Cl2 solution slow decomposition occurs to form the VIII complex [V2Cl6{o-C6H4(AsMe2)2}2]. Six-coordination is also found in [VCl4{MeC(CH2AsMe2)3}] and [VCl4{Et3As)2]. Hydrolysis of these complexes occurs readily to form vanadyl (VO2+) species, pure samples of which are obtained by reaction of [VOCl2(thf)2(H2O)] with the arsines to form green [VOCl2{o-C6H4(AsMe2)2}], [VOCl2{MeC(CH2AsMe2)3}(H2O)] and [VOCl2(Et3As)2]. Green [VOCl2(o-C6H4(PMe2)2}] is formed from [VOCl2(thf)2(H2O)] and the ligand. The [VOCl2{o-C6H4(PMe2)2}] decomposes in thf solution open to air to form the diphosphine dioxide complex [VO{o-C6H4(P(O)Me2)2}2(H2O)]Cl2, but in contrast, the products formed from similar treatment of [VCl4{o-C6H4(AsMe2)2}x] or [VOCl2{o-C6H4(AsMe2)2}] contain the novel arsenic(V) cation [o-C6H4(AsMe2Cl)(μ-O)(AsMe2)]+. X-ray crystal structures are reported for [V2Cl6{o-C6H4(AsMe2)2}2], [VO(H2O){o-C6H4(P(O)Me2)2}2]Cl2, [o-C6H4(AsMe2Cl)(μ-O)(AsMe2)]Cl·[VO(H2O)3Cl2] and powder neutron diffraction data for [VCl4{o-C6H4(AsMe2)2}2]. 相似文献
78.
Fernando de la Peña Moreno Gracia Patricia BlanchGema Flores Maria Luisa Ruiz del Castillo 《Journal of chromatography. A》2010,1217(7):1083-1088
A method based on the use of the through oven transfer adsorption–desorption (TOTAD) interface in on-line coupling between reversed phase liquid chromatography and gas chromatography (RPLC–GC) for the determination of chiral volatile compounds was developed. In particular, the method was applied to the study of the influence of methyl jasmonate (MJ) treatment on the production and enantiomeric composition of selected aroma compounds in strawberry. The compounds studied were ethyl 2-methylbutanoate, linalool and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (i.e. furaneol), which were examined on days 3, 6 and 9 after treatment. The method developed resulted in relative standard deviations (RSDs) of 21.6%, 8.1% and 9.8% and limits of detection (LD) of 0.04, 0.07 and 0.02 mg/l for ethyl 2-methylbutanoate, linalool and furaneol, respectively. The application of the RPLC–TOTAD–GC method allowed higher levels of ethyl 2-methylbutanoate, linalool and furaneol to be detected, particularly after 9 days of treatment. Besides, MJ demonstrated to affect the enantiomeric distribution of ethyl 2-methylbutanoate. On the contrary, the enantiomeric composition of linalool and furaneol kept constant in both control and MJ-treated strawberries throughout the study. These results are discussed. 相似文献
79.
Francesco Paoli Antonio Ledda Matthew Spinks Hector Freytes Roberto Giuntini 《International Journal of Theoretical Physics》2011,50(12):3882-3902
The purpose of the present article is to extend the scope of some investigations about abstract logics arising quite naturally
out of Quasi-MV algebras (for short, qMV algebras) also to ?{¢}\sqrt{^{\prime}} qMV algebras. We will therefore introduce, mutually compare and (in some cases) axiomatise several logics arising out of
the variety of ?{¢}\sqrt{^{\prime}} qMV algebras and out of some important subclasses of such. Subsequently, we will investigate the same logics by resorting
to the methods and techniques of abstract algebraic logic. 相似文献
80.
Keil R Perez-Leija A Dreisow F Heinrich M Moya-Cessa H Nolte S Christodoulides DN Szameit A 《Physical review letters》2011,107(10):103601
Coherent states and their generalizations, displaced Fock states, are of fundamental importance to quantum optics. Here we present a direct observation of a classical analogue for the emergence of these states from the eigenstates of the harmonic oscillator. To this end, the light propagation in a Glauber-Fock waveguide lattice serves as equivalent for the displacement of Fock states in phase space. Theoretical calculations and analogue classical experiments show that the square-root distribution of the coupling parameter in such lattices supports a new family of intriguing quantum correlations not encountered in uniform arrays. Because of the broken shift invariance of the lattice, these correlations strongly depend on the transverse position. Consequently, quantum random walks with this extra degree of freedom may be realized in Glauber-Fock lattices. 相似文献