排序方式: 共有129条查询结果,搜索用时 53 毫秒
101.
102.
Protein A-coated magnetic beads (0.3 mum) have been trapped in a small portion of a neutrally coated capillary (50 mum id). Anti-beta-lactoglobulin (beta-LG) antibodies have then been immobilized on the beads through strong affinity with protein A to subsequently capture beta-LG from model or real samples. Once the immunocomplexes formed at physiological pH, a discontinuous buffer system has been used to release the partners and preconcentrate them by transient ITP. The antigens and antibodies have finally been separated by CZE and detected by UV absorbance. An LOQ of 55 nM has been achieved. This methodology has been applied to quantify native beta-LG in pasteurized and ultra-high-temperature-treated bovine milk. All the described procedures, including immunosorbent preparation, sample extraction, cleanup, preconcentration, and separation are completely automated on a commercial CE instrument. As this CE immunoassay method is simple, rapid, selective, and sensitive, it should be a practical and attractive technology for the analysis of complicated biological samples. 相似文献
103.
Vanessa Naffaa Isabelle Hochar Chryane Lama Romain Magny Anne Regazzetti Pierre Gressens Olivier Laprvote Nicolas Auzeil Anne-Laure Schang 《Molecules (Basel, Switzerland)》2022,27(7)
In the central nervous system, the process of myelination involves oligodendrocytes that wrap myelin around axons. Myelin sheaths are mainly composed of lipids and ensure efficient conduction of action potentials. Oligodendrocyte differentiation is an essential preliminary step to myelination which, in turn, is a key event of neurodevelopment. Bisphenol A (BPA), a ubiquitous endocrine disruptor, is suspected to disrupt this developmental process and may, thus, contribute to several neurodevelopmental disorders. In this study, we assessed the effect of BPA on oligodendrocyte differentiation through a comprehensive analysis of cell lipidome by UHPLC-HRMS. For this purpose, we exposed the oligodendroglial cell line Oli-neu to several BPA concentrations for 72 h of proliferation and another 72 h of differentiation. In unexposed cells, significant changes occurred in lipid distribution during Oli-neu differentiation, including an increase in characteristic myelin lipids, sulfatides, and ethanolamine plasmalogens, and a marked remodeling of phospholipid subclasses and fatty acid contents. Moreover, BPA induced a decrease in sulfatide and phosphatidylinositol plasmalogen contents and modified monounsaturated/polyunsaturated fatty acid relative contents in phospholipids. These effects counteracted the lipid remodeling accompanying differentiation and were confirmed by gene expression changes. Altogether, our results suggest that BPA disrupts lipid remodeling accompanying early oligodendrocyte differentiation. 相似文献
104.
Anne-Laure Dalibard 《Archive for Rational Mechanics and Analysis》2009,192(1):117-164
We study the limit as ε → 0 of the entropy solutions of the equation . We prove that the sequence u
ε
two-scale converges toward a function u(t, x, y), and u is the unique solution of a limit evolution problem. The remarkable point is that the limit problem is not a scalar conservation
law, but rather a kinetic equation in which the macroscopic and microscopic variables are mixed. We also prove a strong convergence
result in . 相似文献
105.
In this note, we compute the split Grothendieck ring of a generalized category of Soergel bimodules of type , where we take one generator for each reflection. We give a presentation by generators and relations of it and a parametrization of the indecomposable objects of the category, by realizing them as rings of regular functions on certain unions of graphs of group elements on a reflection faithful representation. 相似文献
106.
Agathe Fanost Laurence de Viguerie Guylaine Ducouret Guillaume Mriguet Philippe Walter Helen Glanville Anne-Laure Rollet Maguy Jaber 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2022,134(1):e202112108
Egg-tempera painting is a pictorial technique widely used in the Middle Ages, although poorly studied in its physico-chemical aspects until now. Here we show how NMR relaxometry and rheology can be combined to probe egg-tempera paints and shed new light on their structure and behavior. Based on recipes of the 15th century, model formulations with egg yolk and green earth have been reproduced to characterize the physicochemical properties of this paint at the mesoscopic and macroscopic scales. The rheological measurements highlight a synergetic effect between green earth and egg yolk, induced by the interactions between them and the structural organisation of the system. 1H NMR relaxometry emphasizes the presence and the structure of a network formed by the yolk and the pigment. 相似文献
107.
High-field, multifrequency EPR data are presented for the alum CsMn(SO4)2.12D2O, containing the [Mn(OD2)6](3+) cation. The data are interpreted using the conventional S=2 spin Hamiltonian, and the following parameters determined for the data obtained below 30 K: D=-4.491(7) cm(-1), E=0.248(5) cm(-1), gx=1.981(5), gy=1.993(5), gz=1.988(5). Although the deviation of the MnO6 framework from idealized D(4h) symmetry is small, the magnitude of E/D is significant. The E parameter is related to ligand field parameters derived from the optical absorption spectrum. The rhombic anisotropy is shown to arise as a consequence of the pi-anisotropic nature of the manganese(III)-water interaction. 相似文献
108.
Anne-Laure Rollet Catherine Bessada Aïdar Rakhmatoulline Yannick Auger Philippe Melin Marc Gailhanou Dominique Thiaudire 《Comptes Rendus Chimie》2004,7(12):1135-1140
The local structure in molten YF3–LiF and LaF3–LiF binaries has been investigated by NMR and EXAFS spectroscopy. For YF3–LiF, the high-temperature 19F and 7Li NMR spectra have been recorded in situ in the molten state for compositions ranging from pure LiF to pure YF3. The LaF3–LiF system has been studied by 19F and 139La NMR and EXAFS spectroscopy at the LIII edge of La. The local environment around the La3+ in the molten state does not depend on the composition, while 19F chemical shift evolution confirms the progressive formation of bridged species. To cite this article: A.-L. Rollet et al., C. R. Chimie 7 (2004).
Résumé
Étude in situ par spectroscopies RMN et EXAFS à haute température de fluorures de terres rares fondus. La structure locale des mélanges fondus YF3–LiF et LaF3–LiF a été étudiée par spectroscopies RMN et EXAFS à haute température. Pour le système YF3–LiF, les spectres RMN à haute température de 19F et 7Li ont été enregistrés in situ dans le liquide pour différentes compositions variant de LiF pur à YF3 pur. Le système LaF3–LiF a été étudié par RMN de 19F et 139La, et par EXAFS au seuil LIII du lanthane. L’environnement autour du La3+ à l’état fondu ne dépend pas de la composition, alors que les évolutions du déplacement chimique du fluor confirment la formation progressive d’espèces pontantes. Pour citer cet article : A.-L. Rollet et al., C. R. Chimie 7 (2004). 相似文献109.
Dobe C Noble C Carver G Tregenna-Piggott PL McIntyre GJ Barra AL Neels A Janssen S Juranyi F 《Journal of the American Chemical Society》2004,126(50):16639-16652
Variable-temperature spectroscopic and crystallographic studies on the chromium(II) Tutton's salts, (MI)2Cr(X2O)6(SO4)2, where MI = ND4+, Rb+, or Cs+, and X = H or D, are reported. Inelastic neutron scattering (INS) and multifrequency EPR experiments facilitate a rigorous definition of the ground-state electronic structure from 1.5 up to 296 K, which is unprecedented for a high-spin d4 complex. Modeling of the INS data using a conventional S = 2 spin Hamiltonian reveals a dramatic variation in the axial and rhombic zero-field-splitting parameters. For the ammonium salt, D and E are -2.454(3) and 0.087(3) cm(-1) at 10 K and -2.29(2) and 0.16(3) cm(-1) at 250 K, respectively. A temperature variation in the stereochemistry of the [Cr(D2O)6]2+ complex is also identified, with an apparent coalescence of the long and medium Cr-O bond lengths at temperatures above 150 K. The corresponding changes for the rubidium and cesium salts are notable, though less pronounced. The experimental quantities are interpreted using a 5Ee Jahn-Teller Hamiltonian, perturbed by anisotropic strain. It is shown that good agreement can be obtained only by employing a model in which the anisotropic strain is itself temperature dependent. A new theoretical approach for calculating variable-temperature EPR spectra of high-spin d4 complexes, developed within the 5Ee coupling model, is described. Differences between spin-Hamiltonian parameters determined by INS and EPR are consistent with those of the different time scales of the two techniques. 相似文献
110.
Let (X,Y) be a bivariate random vector. The estimation of a probability of the form P(Y ≤ y |X > t) is challenging when t is large, and a fruitful approach consists in studying, if it exists, the limiting conditional distribution of the random
vector (X,Y), suitably normalized, given that X is large. There already exists a wide literature on bivariate models for which this limiting distribution exists. In this
paper, a statistical analysis of this problem is done. Estimators of the limiting distribution (which is assumed to exist)
and the normalizing functions are provided, as well as an estimator of the conditional quantile function when the conditioning
event is extreme. Consistency of the estimators is proved and a functional central limit theorem for the estimator of the
limiting distribution is obtained. The small sample behavior of the estimator of the conditional quantile function is illustrated
through simulations. Some real data are analysed. 相似文献