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51.
Radu-Bogdan Munteanu 《Israel Journal of Mathematics》2012,190(1):307-324
In this paper we give an example of an ergodic non-singular transformation of type III, which satisfies Krieger’s Property A, but which is not orbit equivalent to any product type odometer. 相似文献
52.
From the peculiarities of Temperature-programmed reduction (TPR) method and using the Sestak–Berggren conversion function, we describe first the TPR curve simulation procedure. The influence of the Sestak–Berggren exponents on the TPR peak maximum and shape is demonstrated, by analyzing several synthetic TPR profiles. Finally, the kinetic parameters of Au/CeO2 promoted with yttrium as well as those of Au/CeO2–Al2O3 promoted with V2O5 are discussed. 相似文献
53.
Ovidiu Munteanu 《Advances in Mathematics》2010,223(1):198-219
In this paper we investigate the existence of a solution to the Poisson equation on complete manifolds with positive spectrum and Ricci curvature bounded from below. We show that if a function f has decay f=O(r−1−ε) for some ε>0, where r is the distance function to a fixed point, then the Poisson equation Δu=f has a solution u with at most exponential growth.We apply this result on the Poisson equation to study the existence of harmonic maps between complete manifolds and also existence of Hermitian-Einstein metrics on holomorphic vector bundles over complete manifolds, thus extending some results of Li-Tam and Ni.Assuming moreover that the manifold is simply connected and of Ricci curvature between two negative constants, we can prove that in fact the Poisson equation has a bounded solution and we apply this result to the Ricci flow on complete surfaces. 相似文献
54.
55.
Carbon paste electrodes were modified with a nitrofluorenone derivative, 2,4,7-trinitro-9-fluorenone, adsorbed on zirconium phosphate (ZP). After electrochemical reduction of the fluorenone derivative, it turns into a very efficient mediator for electrocatalytic NADH oxidation, with a formal potential of about +250 mV vs. Ag/AgCl. The electrochemistry and the electrocatalytic properties of the mediator were investigated with cyclic voltammetry and rotating disk electrode methodology. The second order rate constant with NADH was evaluated and found to be higher than 10(6) M(-1) s(-1), thus approaching true diffusion controlled currents for NADH oxidation. 相似文献
56.
An efficient one pot access to variously substituted thieno[2,3‐b]thiophene is described. The title compounds were obtained from 1,3‐dicarbonyl or equivalent compounds, carbon disulfide and halomethyl derivatives in good to high yields and fully characterized. 相似文献
57.
Maria Cazacu Angelica Vlad Grigore Munteanu Anton Airinei 《Journal of polymer science. Part A, Polymer chemistry》2008,46(5):1862-1872
New polyazomethines have been synthesized by the reaction between 2,5‐dihydroxy‐1,4‐benzoquinone and siloxane diamines differing by the siloxane sequence length. A dimer has also been prepared as a model compound. The products were characterized by spectral (FTIR and 1H‐NMR) and elemental analyses, GPC, viscosity measurements, solubility tests, and transmission electron microscopy (TEM). The different properties have been investigated by adequate techniques: thermal (DSC and TGA), spectral (UV–vis and fluorescence spectroscopy), redox (Differential Pulse Voltammetry). pH‐sensitivity and metal complexing ability were also evaluated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1862–1872, 2008 相似文献
58.
The formulation of a particular fluid--structure interaction as an optimal
control problem is the departure point of this work.
The control is the vertical component of the force acting on the
interface and the observation is the vertical component of the velocity of the fluid
on the interface. This approach permits us to solve the coupled fluid--structure problem
by partitioned procedures. The analytic expression for the gradient of the cost function is obtained in order to devise accurate
numerical methods for the minimization problem.
Numerical results arising from blood flow in arteries are presented.
To solve the optimal control problem numerically, we use a quasi-Newton method
which employs the analytic gradient of the cost function and the approximation of the inverse
Hessian is updated by the Broyden, Fletcher, Goldforb, Shano (BFGS) scheme.
This algorithm is faster than fixed point with relaxation or block Newton methods. 相似文献
59.
Two recently reported tin complexes, which incorporate both Sn(I) and Sn(III) sites in their structure, have been examined by temperature-dependent 119Sn M?ssbauer effect (ME) spectroscopy. The distinct hyperfine parameters of the two sites make it possible to assign relative occupancies of the two sites (at 90 K) on the basis of the recoil-free fraction data extracted from the ME spectra. The temperature dependencies of the recoil-free fractions, elucidated from the ME spectra, show that the metal-atom dynamics are very similar for the two sites in the temperature range 90相似文献
60.
Photoluminescence attributed to excitons bound to neutral impurities has been observed from GaAs quantum wells in AlxGa1?xAs-GaAs heterostructures grown by molecular beam epitaxy. The quantum wells were either doped with [Be] ≈ 1017 cm-3 or Zn-diffused. At low temperatures both single and multiple quantum wells exhibited this extrinsic luminescence which is ascribed to the radiative recombination of the n=1 ground state heavy hole exciton E1h bound to a neutral acceptor Ao. The dissociation energy ED of the Ao-E1h complex is obtained directly from the measured separation of this extrinsic peak from the intrinsic E1h free exciton peak. For 46Å wide GaAs wells, ED=6.5meV and ED decreases with increasing well width. 相似文献