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排序方式: 共有603条查询结果,搜索用时 219 毫秒
51.
Montserrat Solé Jennifer P. Shaw Patricia E. Frickers James W. Readman Thomas H. Hutchinson 《Analytical and bioanalytical chemistry》2010,396(2):649-656
Environmental risk assessments of human pharmaceuticals and other ‘emerging contaminants’ should integrate both population-relevant
endpoints and biomarkers of potential modes of action in a range of species. Adult Mytilus galloprovincialis were exposed to the beta-adrenergic receptor blocker propranolol or to the anti-inflammatory drug acetaminophen (paracetamol),
both commonly used therapeutic drugs present in aquatic ecosystems. Mussels were exposed under semi-static conditions for
10 days to either acetaminophen (CAS number 103-90-2; mean measured concentrations 23 and 403 μg/L) or propranolol hydrochloride
(CAS number 318-98-9; mean measured propranolol concentrations 11 and 147 μg/L) at 15 ± 1 °C sea water. Feeding rate was assessed
as an indicator of general toxicity. For propranolol, the 10-day no-observed effect concentration (feeding rateNOEC) and lowest observed effect concentration (feeding rateLOEC) were 11 and 147 μg/L, respectively. For acetaminophen, feeding rate was increased at both 23 and 403 μg/L, suggesting
a 10-day feeding rateNOEC of 403 μg/L. Primarily, phase I carboxylesterase (CbE), phase II glutathione S-transferase (GST) and the anti-oxidant catalase activities were evaluated in digestive gland. Gill GST and acetylcholinesterase
(AChE) activities were also measured. Lipid peroxidation (LPO) levels were measured in both tissues to assess oxidative stress.
Some enzymatic activities in liver were also reduced after propranolol exposure whilst acetaminophen enhanced them (CbE p < 0.05). Acetaminophen exposure significantly increased hepatic LPO levels and inhibited AChE activity in gill (10-day NOEC
and LOEC of 23 and 403 μg/L, respectively), whereas propranolol (11 μg/L) enhanced gill GST. 相似文献
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53.
Krzysztof K. Zborowski Miquel Solà Jordi Poater Leonard M. Proniewicz 《Journal of Physical Organic Chemistry》2011,24(6):499-506
The aim of this project is to study the aromatic properties of various forms (neutral, cationic, and anionic) of selected hydroxypyrones (pyromeconic acid, maltol, and ethylmaltol) and their metalcomplexes with aluminum, gallium, and indium ions. Aromaticity of hydroxypyrone metalcomplexes is important because it can influence the stability of such complexes, which is crucial for their applications in medicinal and environmental chemistry. Results from ten different indices of aromaticity (HOMA, NICS(0), NICS(1), NICSscan, ASEiso, PDI, FLU, Iring, MCI, and KMCI) show that aromaticity in hydroxypyrones decreases in the order cations > neutral molecules > anions. Performed calculations situate the aromaticities of ligands in metalcomplexes close to their respective cations. This means that complexation causes a significant increase of the aromaticity of ligands, which stabilizes formed chelatocomplexes. On the other hand, we clearly show that rings that are involved in binding metal ions are not aromatic. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
54.
Pedro Solórzano 《Journal of Geometric Analysis》2014,24(4):2072-2123
If a sequence of Riemannian manifolds, X i , converges in the pointed Gromov–Hausdorff sense to a limit space, X ∞, and if E i are vector bundles over X i endowed with metrics of Sasaki-type with a uniform upper bound on rank, then a subsequence of the E i converges in the pointed Gromov–Hausdorff sense to a metric space, E ∞. The projection maps π i converge to a limit submetry π ∞ and the fibers converge to its fibers; the latter may no longer be vector spaces but are homeomorphic to \(\mathbb {R}^{k}/G\) , where G, henceforth called the wane group, is a closed subgroup of O(k) that depends on the basepoint and that is defined using the holonomy groups on the vector bundles. The norms μ i =∥?∥ i converge to a map μ ∞ compatible with the rescaling in \(\mathbb {R}^{k}/G\) and the \(\mathbb {R}\) -action on E i converges to an \(\mathbb {R}\) -action on E ∞ compatible with the limiting norm. A natural notion of parallelism is given to the limiting spaces by considering curves whose length is unchanged under the projection. The class of such curves is invariant under the \(\mathbb {R}\) -action and each such curve preserves norms. The existence of parallel translation along rectifiable curves with arbitrary initial conditions is also exhibited. Also, necessary conditions for uniqueness of parallel translates are given in terms of the wane groups. In the special case when the sequence of vector bundles has a uniform lower bound on holonomy radius (as in a sequence of collapsing flat tori to a circle), the limit fibers are vector spaces. Under the opposite extreme, e.g., when a single compact n-dimensional manifold is rescaled to a point, the limit fiber is \(\mathbb {R}^{n}/H\) where H is the closure of the holonomy group of the compact manifold considered. Both these examples have uniqueness of parallel translates. However, examples for non-uniqueness are also produced by looking at isolated conical singularities. 相似文献
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57.
In the search for phenomenological evidence of supersymmetry through the indirect method of quantum signatures, it is useful
to seek correlations of the non-standard quantum effects in low and high energy proceses, such as those involving on one hand
the properties of theB-mesons and on the other hand the physics of the top quark and of the Higgs bosons. There are regions of the MSSM parameter
space where the potential quantum SUSY signatures in the two energy regimes are strongly interwoven and therefore the eventual
detection of these correlated quantum effects would strongly point towards the existence of underlying supersymmetric dynamics. 相似文献
58.
Xavier Fradera Jordi Poater Sílvia Simon Miquel Duran Miquel Solà 《Theoretical chemistry accounts》2002,108(4):214-224
This article presents an overview of recent advances in the study of electron pairing through the use of localization and
delocalization indices obtained from double integration over atomic basins of the exchange–correlation density in the framework
of the atoms-in-molecules theory. These localization and delocalization indices describe the intra- and interatomic distribution
of the electron pairs in a molecule. The main results of the application of these second-order indices to the analysis of
molecular structure and chemical reactivity are briefly reviewed. It is shown that localization and delocalization indices
represent a powerful tool to describe the electron-pair structure of molecules, which, in turn, provides deeper insight into
relevant chemical phenomena such as electron correlation effects and the formation of localized α, β electron pairs.
Received: 8 April 2002 / Accepted: 26 June 2002 / Published online: 6 September 2002
Acknowledgements. Financial help was furnished by the Spanish DGES projects no. PB98-0457-C02-01 and BQU2002-04112-C02-02. J.P. thanks the
Departament d'Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya for benefiting from a doctoral
fellowship, no. 2000FI-00582. M.S. is indebted to the Departament d'Universitats, Recerca i Societat de la Informació of the
Generalitat de Catalunya for financial support through the Distinguished University Research Promotion, 2001. We also thank
the Centre de Supercomputació de Catalunya for providing us with computing facilities.
Correspondence to: M. Solà e-mail: miquel.sola@udg.es 相似文献
59.
Isotactic rac‐Lactide Polymerization with Copper Complexes: The Influence of Complex Nuclearity 下载免费PDF全文
Solène Fortun Pargol Daneshmand Prof. Dr. Frank Schaper 《Angewandte Chemie (International ed. in English)》2015,54(46):13669-13672
Diiminopyrrolide copper alkoxide complexes, LCuOR (OR1=N,N‐dimethylamino ethoxide, OR2=2‐pyridyl methoxide), are active for the polymerization of rac‐lactide at ambient temperature in benzene to yield polymers with Mw/Mn=1.0–1.2. X‐ray diffraction studies showed bridged dinuclear complexes in the solid state for both complexes. While LCuOR1 provided only atactic polylactide, LCuOR2 produced partially isotactic polylactide (Pm=0.7). The difference in stereocontrol is attributed to a dinuclear active species for LCuOR2 in contrast to a mononuclear species for LCuOR1. 相似文献
60.
Bertrand Reuillard Solène Gentil Marie Carrière Alan Le Goff Serge Cosnier 《Chemical science》2015,6(9):5139-5143
We report the non-covalent functionalization of a multi-walled carbon nanotube (MWCNT) electrode with a biomimetic model of the horseradish peroxidase (HRP) active site. By modifying the MWCNT electrode surface with imidazole-modified polypyrrole, a new biomimetic complex of HRP was synthesized on the MWCNT sidewalls via the coordination of imidazole (Im) to the metal centre of iron protoporphyrin IX, affording (Im)(PP)FeIII. Compared to the pi-stacking of non-coordinated (PP)FeIII on a MWCNT electrode, the (Im)(PP)FeIII-modified MWCNT electrode exhibits higher electrocatalytic activity with an I max = 0.52 mA cm–2 for the reduction of H2O2, accompanied by a high onset potential of 0.43 V vs. Ag/AgCl. The performances of these novel surface-confined HRP mimics were compared to those of a MWCNT electrode modified by HRP. Although the enzyme electrode displays a higher electrocatalytic activity towards H2O2 reduction, the (Im)(PP)FeIII-modified MWCNT electrode exhibits a markedly higher operational stability, retaining 63% of its initial activity after one month. 相似文献