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131.
132.
Centineo G Rodríguez-González P Blanco González E García Alonso JI Sanz-Medel A Font Cardona N Aranda Mares JL Ballester Nebot S 《Analytical and bioanalytical chemistry》2006,384(4):908-914
A standard GC-MS instrument with electron impact ionisation has been used to develop a fast, simple and reliable method for
the simultaneous determination of monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) in water samples. Isotope dilution
analysis (IDA) is used for the determination of species, taking advantage of a commercially available spike solution containing
a mixture of MBT, DBT and TBT enriched in 119Sn. Method detection limits for 100-mL samples were between 0.18 and 0.25 ng L−1 for the three butyltin compounds with typical RSD between 2 and 4% at levels between 100 and 10 ng L−1, respectively. Recovery of tin species in spiked samples (natural water, wastewater and seawater) was quantitative. The stability
of butyltin compounds in collected seawater samples was also studied. The addition of a 1% (v/v) glacial acetic acid preserved
tin species in the samples for at least 5 days at room temperature. The IDA method was finally implemented in a routine testing
laboratory and it was subsequently accredited by the Spanish National Accreditation Body according to the requirements of
UNE-EN ISO/IEC 17025. 相似文献
133.
González-Alvarez A Alfonso I Díaz P García-España E Gotor V 《Chemical communications (Cambridge, England)》2006,(11):1227-1229
The highly enantioselective molecular recognition of the malate dianion by a synthetic receptor in aqueous solution has been studied by potentiometric titrations, mass spectrometry (ESI-MS), diffusion measurements (PGSE NMR) and molecular modeling. 相似文献
134.
González-Alvarez A Alfonso I Gotor V 《Chemical communications (Cambridge, England)》2006,(21):2224-2226
Cadmium promoted diastereoselective amplification of a single member from a dynamic combinatorial library of stereoisomeric oligoimines of different sizes allows the efficient preparation of a new macrocyclic polyamine. 相似文献
135.
Rivero IA Gonzalez T Diaz-Garcia ME 《Combinatorial chemistry & high throughput screening》2006,9(7):535-544
The automated parallel solid-phase synthesis of a 17-member library of metallothionein-mimic decapeptides carrying a Lariat ether group is described. The peptides were synthesized in good yield and the identity and quality of each product were performed by mass spectrometry and IR. Subsequently, in the presence of europium(III) ions as fluorescent reporter, each compound was screened, both attached to the resin and cleaved off, for their sensing behavior towards metal ions (Cd(2+),Hg(2+), Cu(2+), Mg(2+) and Ca(2+)) using fluorimetric techniques. Several of these Cys-enriched synthetic peptides showed surprisingly low detection limits for Cd(2+) and Hg(2+). The analytical potential of these metallothionein-mimic decapeptides as metal ion recognition materials for sensor development is outlined. Finally, the sensing response mechanism, based on an energy transfer process and a metal ion allosteric interaction, is proposed. 相似文献
136.
Duran Mario; Muga Ignacio; Nedelec Jean-Claude 《IMA Journal of Applied Mathematics》2006,71(6):853-876
** Email: mduran{at}ing.puc.cl*** Email: ignacio.muga{at}ucv.cl**** Email: nedelec{at}cmapx.polytechnique.fr
In this article, we study the existence and uniqueness of outgoingsolutions for the Helmholtz equation in locally perturbed half-planeswith passive boundary. We establish an explicit outgoing radiationcondition which is somewhat different from the usual Sommerfeld'sone due to the appearance of surface waves. We work with thehelp of Fourier analysis and a half-plane Green's function framework.This is an extended and detailed version of the previous articleDurán et al. (2005, The Helmholtz equation with impedancein a half-plane. C. R. Acad. Sci. Paris, Ser. I, 340, 483488). 相似文献
137.
Ignacio García Nuria Iturriza Hans Grande Julián González 《Journal of magnetism and magnetic materials》2010,322(13):1822-1827
The domain structure of a magnetostrictive Fe40Ni38Mo4B18 amorphous ribbon has been studied using magnetic force microscopy (MFM) at room temperature. First, the evolution of the magnetic domain patterns as a function of the annealing temperature has been investigated. In samples heat treated at 250 and 450 °C for 1 h, a transformation from 90° to 180° domain wall has been clearly observed, while the sample heat treated at 700 °C for 1 h showed a magnetic phase fixed by the crystalline anisotropy. Additionally, the evolution of the magnetic domain structure by applying a DC current was recorded by the MFM technique. For current annealed samples at 1 A for 1, 30 and 60 min, a transformation between different domain patterns has been observed. Finally, in samples treated by the current annealing method under simultaneous stress, an increase of the annealing time gives rise to a different magnetic structure arising from the development of transverse magnetic anisotropy. 相似文献
138.
Generalizing the well known and exploited relation between Heyting and Nelson algebras to semi-Heyting algebras, we introduce the variety of semi-Nelson algebras. The main tool for its study is the construction given by Vakarelov. Using it, we characterize the lattice of congruences of a semi-Nelson algebra through some of its deductive systems, use this to find the subdirectly irreducible algebras, prove that the variety is arithmetical, has equationally definable principal congruences, has the congruence extension property and describe the semisimple subvarieties. 相似文献
139.
Mathematical Programming - In this paper, we present two new methods for solving convex mixed-integer nonlinear programming problems based on the outer approximation method. The first method is... 相似文献
140.