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951.
Staphylococcal enterotoxin A (SEA) is an exotoxin excreted mainly by Staphylococcus aureus and nowadays is the most prevalent compound in staphylococcal food poisoning worldwide. SEA is highly heat-resistant, and usual cooking times and temperatures are unlikely to completely inactivate it. A procedure for extraction of this toxin based on protein precipitation with a mixture of dichloromethane and acidified water was used before SDS-PAGE separation of soluble proteins. Finally, bands of interest were excised from the gel and in-gel enzymatic digestion was done. SEA from pasteurized milk was detected with matrix-assisted laser-desorption/ionization-time of flight (MALDI-TOF) mass spectrometry. Nineteen peptides (range 800-2400 Da) were identified as products of trypsin cleavage of the SEA standard with a score of 204 and 73% coverage of the protein sequence, whereas thirteen peptides were revealed for SEA extracted from milk with a score of 148 and 58% sequence coverage obtained. This procedure has been applied successfully for identification of SEA in milk. 相似文献
952.
Stéphanie Rat Michael Bosco Marie-Laure Tavernier Philippe Michaud Anne Wadouachi José Kovensky 《Comptes Rendus Chimie》2011,14(2-3):307-312
Substitution of a glucuronic acid trisaccharide was easily performed in one step under microwave irradiation, affording a product resulting from simultaneous glycosylation, esterification and a butyl ether formation. 相似文献
953.
The authors introduce a new class of finite dimensional algebras called extended canonical, and determine the shape of their derived categories. Extended canonical algebras arise from a canonical algebra ?? by onepoint extension or coextension by an indecomposable projective module. Our main results concern the case of negative Euler characteristic of the corresponding weighted projective line ${\mathbb{X}}$ ; more specifically we establish, for a base field of arbitrary characteristic, a link to the Fuchsian singularity R of ${\mathbb{X}}$ which for the base field of complex numbers is isomorphic to an algebra of automorphic forms. By means of a recent result of Orlov we show that the triangulated category of the graded singularities of R (in the sense of Buchweitz and Orlov) admits a tilting object whose endomorphism ring is the corresponding extended canonical algebra. Of particular interest are those cases where the attached Coxeter transformation has spectral radius one. A K-theoretic analysis then shows that this happens exactly for 38 cases including Arnold??s 14 exceptional unimodal singularities. The paper is related to recent independent work by Kajiura, Saito and Takahashi. 相似文献
954.
Eugenio Hern��ndez Jos�� Mar��a Martell Maria de Natividade 《Constructive Approximation》2011,33(1):1-14
We study the efficiency of the greedy algorithm for wavelet bases in Lorentz spaces in order to give the near best approximation.
The result is used to give sharp inclusions for the approximation spaces in terms of discrete Lorentz sequence spaces. 相似文献
955.
We study the problem of when the collection of the recession cones of a polyhedral complex also forms a complex. We exhibit
an example showing that this is no always the case. We also show that if the support of the given polyhedral complex satisfies
a Minkowski–Weyl-type condition, then the answer is positive. As a consequence, we obtain a classification theorem for proper
toric schemes over a discrete valuation ring in terms of complete strongly convex rational polyhedral complexes. 相似文献
956.
Jerónimo Aznar Francisco Guijarro José María Moreno-Jiménez 《Annals of Operations Research》2011,190(1):221-238
This paper introduces a new assessment method classification, in which a third procedure, mixed valuation, is jointly included with the traditional economic and non-economic methodologies. The paper considers a case of multiple
actors (from a previous work by the same authors—Aznar et al. (Estudios de Economía Aplicada, 25(2):389–409, 2007), in which a new technique for multicriteria agriculture valuation (MAVAM) was proposed. The method is specifically designed
for situations in which scarce information about the elements being compared (quantified or not) is available. It works in
individual and group decision making contexts and attempts to both obtain and incorporate the objective information associated
with the tangible aspects of the problem and the subjective knowledge associated with the human factor into the valuation
process. It combines two of the most extended multicriteria decision making techniques: the Analytic Hierarchy Process (AHP)
and Goal Programming (GP). The first of these enables tangible and intangible information stemming from known elements to
be collected by using pairwise comparisons; the second allows the scarce information available and the personal approach to
the valuation to be included in the valuation process. The proposed methodology is illustrated by means of its application
to a case of individual and group valuation of an agricultural asset in the La Ribera district, Valencia (Spain). 相似文献
957.
In this paper we present a new framework for identifying preferred solutions to multi-objective binary optimisation problems.
We develop the necessary theory which leads to new formulations that integrate the decision space with the space of criterion
weights. The advantage of this is that it allows for incorporating preferences directly within a unique binary optimisation
problem which identifies efficient solutions and associated weights simultaneously. We discuss how preferences can be incorporated
within the formulations and also describe how to accommodate the selection of weights when the identification of a unique
solution is required. Our results can be used for designing interactive procedures for the solution of multi-objective binary
optimisation problems. We describe one such procedure for the multi-objective multi-dimensional binary knapsack formulation
of the portfolio selection problem. 相似文献
958.
Ohtani R Yoneda K Furukawa S Horike N Kitagawa S Gaspar AB Muñoz MC Real JA Ohba M 《Journal of the American Chemical Society》2011,133(22):8600-8605
Precise control of spin transition temperature (T(c)) is one of the most important challenges in molecular magnetism. A Hofmann-type porous coordination polymer {Fe(pz)[Pt(II)(CN)(4)]} (1; pz = pyrazine) exhibited cooperative spin transition near room temperature (T(c)(up) = 304 K and T(c)(down) = 284 K) and its iodine adduct {Fe(pz)[Pt(II/IV)(CN)(4)(I)]} (1-I), prepared by oxidative addition of iodine to the open metal sites of Pt(II), raised the T(c) by 100 K. DSC and microscopic Raman spectra of a solid mixture of 1-I and 1 revealed that iodine migrated from 1-I to 1 through the grain boundary after heating above 398 K. We have succeeded in precisely controlling the iodine content of {Fe(pz)[Pt(CN)(4)(I)(n)]} (1-In; n = 0.0-1.0), which resulted in consecutive modulation of T(c) in the range 300-400 K while maintaining the hysteresis width. Furthermore, it was demonstrated that iodine migration in the solid mixture was triggered by the spin transition of 1-I. The magnetically bistable porous framework decorating guest interactive open-metal-site in the pore surface makes it possible to modulate T(c) ad arbitrium through unique postsynthetic method using iodine migration. 相似文献
959.
Alves L Ballesteros B Boronat M Cabrero-Antonino JR Concepción P Corma A Correa-Duarte MA Mendoza E 《Journal of the American Chemical Society》2011,133(26):10251-10261
Small gold nanoclusters in a very narrow size distribution (1.1 ± 0.5 nm) have been stabilized onto multiwalled carbon nanotubes (MWCNT). Theoretical studies supported by XPS and (16)O(2)/(18)O(2) isotopic exchange experiments have shown that, on small gold nanoparticles (0.9-1.5 nm), dissociation of molecular O(2) and formation of a surface oxide-like layer is energetically favorable and occurs at room temperature, while O(2) recombination and desorption involves a larger activation barrier. CO titration experiments and theoretical studies demonstrate that the reactivity of the oxidized particles toward CO does not only depend on particle size but also on oxygen coverage. The oxidation-reduction process described is reversible, and the oxidized nanoparticles are active in the epoxidation of styrene with air. 相似文献
960.
The combination of lag-k autocorrelation coefficients (LCCs) and thermogravimetric analyzer (TGA) equipment is defined here as a tool to detect and quantify adulterations of extra virgin olive oil (EVOO) with refined olive (ROO), refined olive pomace (ROPO), sunflower (SO) or corn (CO) oils, when the adulterating agents concentration are less than 14%. The LCC is calculated from TGA scans of adulterated EVOO samples. Then, the standardized skewness of this coefficient has been applied to classify pure and adulterated samples of EVOO. In addition, this chaotic parameter has also been used to quantify the concentration of adulterant agents, by using successful linear correlation of LCCs and ROO, ROPO, SO or CO in 462 EVOO adulterated samples. In the case of detection, more than 82% of adulterated samples have been correctly classified. In the case of quantification of adulterant concentration, by an external validation process, the LCC/TGA approach estimates the adulterant agents concentration with a mean correlation coefficient (estimated versus real adulterant agent concentration) greater than 0.90 and a mean square error less than 4.9%. 相似文献