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Carbon,nitrogen and sulphur isotopic fractionation in captive juvenile hooded seal (Cystophora cristata): Application for diet analysis
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Pablo López-Tarifa Marie-Anne Hervé du Penhoat Rodophe Vuilleumier Marie-Pierre Gaigeot Ursula Rothlisberger Ivano Tavernelli Arnaud Le Padellec Jean-Philippe Champeaux Manuel Alcamí Patrick Moretto-Capelle Fernando Martín Marie-Françoise Politis 《Central European Journal of Physics》2014,12(2):97-102
We use time-dependent density functional theory and Born-Oppenheimer molecular dynamics methods to investigate the fragmentation of doubly ionized uracil in gas phase. Different initial electronic excited states of the dication are obtained by removing electrons from different inner-shell orbitals of the neutral species. We show that shape-equivalent orbitals lead to very different fragmentation patterns revealing the importance of the intramolecular chemical environment. The results are in good agreement with ionion coincidence measurements of uracil collision with 100 keV protons. 相似文献
96.
An approach to model the deterioration of steel structures is presented by transferring the results of a continuum damage mechanics analysis to an extended beam model which can account for the loss of structural integrity. Damage starts at the microscopic level by the initiation, growth and coalescence of voids with decreasing material resistance followed by the formation of microcracks at the mesoscale. Nevertheless, the material behavior can be sufficiently modelled on a phenomenological basis taking into account viscoplasticity, hardening effects and damage evolution. The associated model parameters are identified with the help of an evolutionary algorithm adapting numerical to experimental results. Using the finite element method a nonlocal formulation of the damage variable is required to obtain mesh-independent results by structural analysis. The maximum element size is limited by the small magnitude of the internal length. Therefore, numerical analyses of large scale 3D steel structures are computationally expensive. To reduce the effort a beam element is proposed to account for the plastic hinges and the loss of resistance in the course of damage evolution. The corresponding relationship of bending moment and curvature bases on the continuum damage mechanics model. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
97.
Aldol/elimination reactions of ß-ketoamides with methyl glyoxylate result in highly selective production of Z-α,ß-unsaturated amides. An intramolecular Diels-Alder reaction of a triply activated dienophile derived from chiral dienylamine 7ZE stereospecifically affords chiral bicyclic lactam 11 at room temperature. 相似文献
98.
Janina Möker Ursula Salge-Bartels Joachim Thiem 《Journal of carbohydrate chemistry》2013,32(9):702-710
Syntheses of carbohydrate-functionalized platinum complexes resembling presently employed cytostatics were performed. Mono-allylated sugar substrates obtained in two steps from glucose and galactose were connected with 2-allyl diethyl malonate by cross-metathesis. Following hydrogenation and acidic cleavage of the ester and alkylidene functionalities gave dicarboxylated glycoconjugates, which were transformed into their diammine platinum complexes. The antitumor activities of these platinum complexes were checked by sensitivity testing with 11 lung cancer cell lines. The novel glucose-platinum complex proved to be comparable to the drug carboplatin. 相似文献
99.
Besides human red blood cells (RBC), a standard model used in AFM-single cell force spectroscopy (SCFS), little is known about apparent Young’s modulus (Ea) or adhesion of animal RBCs displaying distinct cellular features. To close this knowledge gap, we probed chicken, horse, camel, and human fetal RBCs and compared data with human adults serving as a repository for future studies. Additionally, we assessed how measurements are affected under physiological conditions (species-specific temperature in autologous plasma vs. 25 °C in aqueous NaCl solution). In all RBC types, Ea decreased with increasing temperature irrespective of the suspension medium. In mammalian RBCs, adhesion increased with elevated temperatures and scaled with reported membrane sialic acid concentrations. In chicken only adhesion decreased with higher temperature, which we attribute to the lower AE-1 concentration allowing more membrane undulations. Ea decreased further in plasma at every test temperature, and adhesion was completely abolished, pointing to functional cell enlargement by adsorption of plasma components. This halo elevated RBC size by several hundreds of nanometers, blunted the thermal input, and will affect the coupling of RBCs with the flowing plasma. The study evidences the presence of a RBC surface layer and discusses the tremendous effects when RBCs are probed at physiological conditions. 相似文献
100.
Suihan Feng Dr. Vibor Laketa Frank Stein Dr. Anna Rutkowska Dr. Aidan MacNamara Dr. Sofia Depner Prof. Ursula Klingmüller Dr. Julio Saez‐Rodriguez Priv.‐Doz. Dr. Carsten Schultz 《Angewandte Chemie (International ed. in English)》2014,53(26):6720-6723
Chemical dimerizers are powerful tools for non‐invasive manipulation of enzyme activities in intact cells. Here we introduce the first rapidly reversible small‐molecule‐based dimerization system and demonstrate a sufficiently fast switch‐off to determine kinetics of lipid metabolizing enzymes in living cells. We applied this new method to induce and stop phosphatidylinositol 3‐kinase (PI3K) activity, allowing us to quantitatively measure the turnover of phosphatidylinositol 3,4,5‐trisphosphate (PIP3) and its downstream effectors by confocal fluorescence microscopy as well as standard biochemical methods. 相似文献