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991.
Rantala A Utriainen M Kaushik N Virta M Välimaa AL Karp M 《Analytical and bioanalytical chemistry》2011,400(4):1041-1049
A bacterial biosensor method for the selective determination of a bioavailable organomercurial compound, methylmercury, is
presented. A recombinant luminescent whole-cell bacterial strain responding to total mercury content in samples was used.
The bacterial cells were freeze-dried and used as robust, reagent-like compounds, without batch-to-batch variations. In this
bacteria-based sensing method, luciferase is used as a reporter, which requires no substrate additions, therefore allowing
homogenous, real-time monitoring of the reporter gene expression. A noninducible, constitutively light-producing control bacterial
strain was included in parallel for determining the overall cytotoxicity of the samples. The specificity of the total mercury
sensor Escherichia coli MC1061 (pmerRBlux) bacterial resistance system toward methylmercury is due to a coexpressed specific enzyme, organomercurial lyase. This enzyme
mediates the cleavage of the carbon–mercury bond of methylmercury to yield mercury ions, which induce the reporter genes and
produce a self-luminescent cell. The selective analysis of methylmercury with the total mercury strain is achieved by specifically
chelating the inorganic mercury species from the sample using an optimized concentration of EDTA as a chelating agent. After
the treatment with the chelating agent, a cross-reactivity of 0.2% with ionic mercury was observed at nonphysiological ionic
mercury concentrations (100 nM). The assay was optimized to be performed in 3 h but results can already be read after 1 h
incubation. Total mercury strain E. coli MC1061 (pmerRBlux) has been shown to be highly sensitive and capable of determining methylmercury at a subnanomolar level in optimized assay
conditions with a very high dynamic range of two decades. The limit of detection of 75 ng/l (300 pM) allows measurement of
methylmercury even from natural samples. 相似文献
992.
Thomas R. Boussie Gary M. Diamond Christopher Goh Keith A. Hall Anne M. LaPointe Margarete K. Leclerc Vince Murphy James A. W. Shoemaker Howard Turner Robert K. Rosen James C. Stevens Francesca Alfano Vincenzo Busico Roberta Cipullo Giovanni Talarico 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2006,118(20):3356-3361
993.
994.
Anne de Cuendias Emmanuel Ibarboure Sébastien Lecommandoux Eric Cloutet Henri Cramail 《Journal of polymer science. Part A, Polymer chemistry》2008,46(13):4602-4616
The purpose of this study is to correlate the nano‐organization in water of coil‐rod‐coil amphiphilic block copolymers constituted of a conjugated segment to their optoelectronic properties. The ABA block copolymer structures, easily achieved via coupling reactions, are based on conjugated rod of dihexylfluorene and 3,4‐ethylenedioxythiophene units linked to two flexible poly(ethylene oxide) or poly[(ethylene oxide)‐ran‐(propylene oxide)] chains. These well‐defined copolymers exhibited a range of specific morphologies in water, a good solvent of coil blocks and a bad solvent of the conjugated rod. Particularly, vesicles and micelles with spherical, cylindrical, or elongated shape were noticed. Correlations were attempted to be established between the weight percent of the conjugated sequence contained in the copolymers, the morphology of the nanostructures obtained by self‐assembly in solution and the resulting optical properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4602–4616, 2008 相似文献
995.
New 2-aminoimidazole (2-AI) and imidazoline derivatives were obtained in three steps through the reduction of N-pyridinium imidates into 1,2-dihydropyridine imidates and oxidative addition of guanidine derivatives. Among the possible transformations, imidate substitution allows selectivity in the last deprotection step, leading to an original 2-aminoimidazolo-imidazoline skeleton. 相似文献
996.
997.
Alexandre Masquelein Anne Quéguiner-Mathieu Jean-Pierre Tignol 《Archiv der Mathematik》2009,93(2):129-138
Izhboldin and Karpenko proved in Math. Z. (234 (2000), 647–695, Theorem 16.10) that any quadratic form of dimension 8 with trivial discriminant and Clifford algebra of
index 4 is isometric to the transfer, with respect to some quadratic étale extension, of a quadratic form similar to a two-fold
Pfister form. We give a new proof of this result, based on a theorem of decomposability for degree 8 and index 4 algebras
with orthogonal involution. 相似文献
998.
An improved strategy for the stereoselective synthesis of glycosides using glycosidases as catalysts
A alternative strategy for the synthesis of glycosides, using glycosidase enzymes, has been developed. In contrast to previous procedures, this new method uses limiting amounts of the acceptor alcohol substrate in combination with an excess of the glycosyl donor. Using this procedure, a series of mono- and disaccharides have been prepared. 相似文献
999.
Michael J. S. Dewar Marye Anne Fox Kay A. Campbell Chia-Chung Chen James E. Friedheim Mary K. Holloway Shi Choon Kim Phillip B. Liescheski Ali M. Pakiari Tze-Pei Tien Eve G. Zoebisch 《Journal of computational chemistry》1984,5(5):480-485
The energies of the lowest singlet (S1) and triplet (T1) states of 28 molecules have been calculated by the “half-electron” (MNDO -HE ) and spin-unrestricted (UMNDO ) versions of MNDO . While most of the calculated values are too negative, because of overestimation of the correlation energy in MNDO -HE and UMNDO , the errors are systematic and depend in an understandable way on the nature of the molecular orbitals (MO S) involved. When appropriate corrections are applied, the calculated energies agree with experiment almost as well as they do for ground states. This justifies the use of MNDO -HE or UMNDO for studies of excited state processes. 相似文献
1000.
Anne E. Vertigan Deborah G. Theodoros Peter G. Gibson Alison L. Winkworth 《Journal of voice》2006,20(3):466-480
SUMMARY: Chronic cough (CC) and paradoxical vocal fold movement (PVFM) are debilitating conditions. PVFM has been given many labels, including vocal cord dysfunction, Munchausen's stridor, functional inspiratory stridor, nonorganic functional or psychogenic upper airway obstruction, factitious asthma, psychogenic stridor, emotional laryngeal wheezing, and episodic laryngeal dyskinesia. Although CC and PVFM have been considered separate entities in many reports, there is preliminary support for the notion that there may be an underlying link between these two conditions. Speech pathologists have become increasingly involved in the treatment of these patients and therefore need to understand the theoretical background of these disorders, the pathophysiological links between the two, and the impact of voice disorders on these populations. The aim of this article is to review the current literature on CC and PVFM from a speech pathology perspective to provide a model for defining and conceptualizing the disorders and to provide a framework for management and future research. 相似文献