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381.
LC Soares EE Alberto RS Schwab PS Taube V Nascimento OE Rodrigues AL Braga 《Organic & biomolecular chemistry》2012,10(32):6595-6599
The ephedrine-based diselenide appears as a new promiscuous catalyst, able to generate optically active alcohols by addition of organozinc to aldehydes (up to 97% ee), and shows powerful GPx like activity, reducing H(2)O(2) to water in only 16.33 min (eleven times faster than PhSeSePh). 相似文献
382.
Bastian Pentenrieder Christoph Schwab 《Numerical Methods for Partial Differential Equations》2012,28(5):1497-1526
For a linear second order elliptic partial differential operator A : V → V′, we consider the boundary value problems Au = f with stationary Gaussian random data f over the dual V′ of the separable Hilbert space V in which the solution u is sought. The operator A is assumed to be deterministic and bijective. The unique solution u = A?1f is a Gaussian random field over V. It is characterized by its mean field Eu and its covariance Cu ∈ V ? V. For a class of Gaussian data f with piecewise analytic covariance kernels Cf ∈ V′ ? V′, we characterize analytic regularity of the covariance Cu of the Gaussian solution u in families of countably normed, weighted Sobolev spaces. To this end, we investigate shift theorems for the (nonhypoelliptic) deterministic tensor PDEs (A ? A)Cu = Cf proposed by Schwab and Todor, (Numer Math 95 (2003), 707–734) for the computation of covariance Cu of the random solution u. The nonhypoelliptic nature of A ? A implies that sing supp(Cu) is in general strictly larger than sing supp(Cf). For a model problem, analyticity and singular support of the solution is characterized completely. Based on our regularity results, we outline an hp‐finite element strategy (Pentenrieder, Ph.D thesis, ETHZurich, Dissertation No. 18729, 2009; Pentenrieder and Schwab, Research Report 2010‐08, Seminar for Applied Mathematics, ETH Zürich, Submitted) to approximate Cu stemming from covariances of stationary Gaussian data f. In the second part (Pentenrieder and Schwab, Research Report 2010–08, Seminar for Applied Mathematics, ETH Zürich, Submitted) of this work, we prove that this discretization gives exponential rates of convergence of the FE approximations, in terms of the number of degrees of freedom. © 2011 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2012 相似文献
383.
Scheinast W Böttcher I Debowski M Dohrmann F Förster A Grosse E Koczoń P Kohlmeyer B Laue F Menzel M Naumann L Schwab E Senger P Shin Y Ströbele H Sturm C Surówka G Uhlig F Wagner A Waluś W Kämpfer B Barz HW;KaoS Collaboration 《Physical review letters》2006,96(7):072301
Differential production cross sections of K+/- mesons have been measured in p + C and p + Au collisions at 1.6, 2.5, and 3.5 GeV proton beam energy. At beam energies close to the production threshold, the K- multiplicity is strongly enhanced with respect to proton-proton collisions. According to microscopic transport calculations, this enhancement is caused by two effects: the strangeness exchange reaction NY --> K- NN and an attractive in-medium K- N potential at saturation density. 相似文献
384.
The first example of a binuclear ruthenium complex involving the p-carborane framework in the bridging ligand is reported. The bridging ligand is a symmetric linear array comprising a central p-carborane unit, two p-phenylene spacers, and two 5-yl-2,2'-bipyridine coordinating units. A homobinuclear Ru(II) complex, with 2,2'-bipyridine as peripheral ligands, was synthesized and characterized. The Ru(II)-Ru(III) mixed-valence species, obtained by partial oxidation, has been investigated with steady-state and time-resolved techniques in CH3CN. The rate of photoinduced electron transfer is 2.3 x 10(8) s(-1). 相似文献
385.
The numerical solution of parabolic problems
with a pseudo-differential operator
by wavelet discretization in space and hp discontinuous Galerkin time stepping is analyzed. It is proved that an approximation for u(T) can be obtained in N points with accuracy
for any integer p ≥ 1 in work and memory which grows logarithmically-linear in N.Supported in part IHP Network Breaking Complexity of the EC (contract number HPRN-CT-2002-00286) with support by the Swiss Federal Office for Science and Education under grant No. BBW 02.0418.Funded by the Swiss National Science Foundation (Grant PBEZ2-102321). 相似文献
386.
We extend the multi-level Monte Carlo (MLMC) in order to quantify uncertainty in the solutions of multi-dimensional hyperbolic systems of conservation laws with uncertain initial data. The algorithm is presented and several issues arising in the massively parallel numerical implementation are addressed. In particular, we present a novel load balancing procedure that ensures scalability of the MLMC algorithm on massively parallel hardware. A new code is described and applied to simulate uncertain solutions of the Euler equations and ideal magnetohydrodynamics (MHD) equations. Numerical experiments showing the robustness, efficiency and scalability of the proposed algorithm are presented. 相似文献
387.
Fabienne Schwab 《Helvetica chimica acta》2023,106(1):e202200136
Nanoagrochemicals conceived based on safe-by-design principles could provide, besides yield increases, real benefits for the environment due to lower losses of agrochemicals to wind drift and rainwater run-off, and lower toxicity to non-target organisms. As an emerging new technology rather than ‘just another’ active ingredient, nanoagrochemicals should be evaluated and compared to conventional products using multiple criteria, including the production costs, efficiency, mode of action, degradability, and (lack of) effects on non-target organisms. Current studies on nanopesticides suggest, on average, ca. 31 % more efficiency and ca. 43 % less toxicity on non-target organisms. Observations of a 5–10-fold increase in efficiency in laboratory studies need validation in the field. The most significant challenges for nanoagrochemicals today are to produce them at competitive costs and overcome the regulatory obstacles to register products containing nanomaterials. 相似文献
388.
Marcel Eck Simon Timm Schwab Taylor Frederick Nelson Katrin Wurst Steffen Iberl David Schleheck Christoph Link Glauco Battagliarin Stefan Mecking 《Angewandte Chemie (International ed. in English)》2023,62(6):e202213438
We report a novel polyester material generated from readily available biobased 1,18-octadecanedicarboxylic acid and ethylene glycol possesses a polyethylene-like solid-state structure and also tensile properties similar to high density polyethylene (HDPE). Despite its crystallinity, high melting point (Tm=96 °C) and hydrophobic nature, polyester-2,18 is subject to rapid and complete hydrolytic degradation in in vitro assays with isolated naturally occurring enzymes. Under industrial composting conditions (ISO standard 14855-1) the material is biodegraded with mineralization above 95 % within two months. Reference studies with polyester-18,18 (Tm=99 °C) reveal a strong impact of the nature of the diol repeating unit on degradation rates, possibly related to the density of ester groups in the amorphous phase. Depolymerization by methanolysis indicates suitability for closed-loop recycling. 相似文献
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