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21.
Walter Craig Ana-Maria Matei 《Proceedings of the American Mathematical Society》2007,135(8):2497-2504
In 1952 H. Lewy established that a hydrodynamic free surface which is at least in a neighborhood of a point situated on the free surface is automatically , possibly in a smaller neighborhood of . This local result is an example which preceeds the theory developed by D. Kinderlehrer, L. Nirenberg and J. Spruck (1977-79), proving that in many cases free surfaces cannot have an arbitrary regularity; in particular, there exist such that if the surface in question is , then automatically is . In this paper we extend their methods to Neumann type problems for free surfaces with surface tension.
22.
Ana-Maria Matei 《Proceedings of the American Mathematical Society》2005,133(7):2183-2192
We prove that for any 1$\">, any compact manifold of three or more dimensions carries Riemannian metrics of volume one with the first eigenvalue of the -Laplacian arbitrarily large.
23.
Liliana-Marinela Ştefan Ana-Maria Pană Geza Bandur Patrick Martin Marcel Popa Lucian-Mircea Rusnac 《Journal of Thermal Analysis and Calorimetry》2013,111(1):789-797
A novel monomer carrying carbohydrate moiety was prepared by simple reaction of methacrylic acid with 3-O-(2′,3′-epoxy-propyl)-1,2:5,6-di-O-isopropylidene-α-d-glucofuranose. Another d-glucose oligomer was synthesized by the polycondensation of a dicarboxylic acid including the carbohydrate residue into the main polymeric chain, 3-O-benzyl-5,6-(bis-O-(acryloyloxy))-1,2-di-O-isopropylidene-α-d-glucofuranose, with propane-1,3-diol using p-toluenesulfonic acid as catalyst. These products were copolymerized with styrene and 2-hydroxypropyl methacrylate, respectively, at different mass ratios, using benzoyl peroxide as initiator. Differential scanning calorimetry was performed in order to study the copolymerization process of the monomer and oligomer into the chosen co-monomers, respectively, and the activation energy of this process was evaluated using Kissinger–Akahira–Sunose (KAS) method. The storage and loss modulus of the obtained glycopolymers were evaluated using dynamic mechanical analysis. The thermal stability of the obtained products was studied via thermogravimetry. 相似文献
24.
Dan Donescu Liana Fusulan Cristian Petcu Marilena Vasilescu Calin Deleanu Silvia Udrea 《Macromolecular Symposia》2002,179(1):315-330
The microemulsion system containing vinyl acetate (Vac), silane derivatives tetraethoxysilane (TEOS), methacryloxypropyltrimethoxysilane (MPTS), vinyltriethoxysilane (VTES), methyltriethoxysilane (MeTES), octyltriethoxysilane (OTES), nonylphenol etoxylated with 25 mol of ethylene oxyde (NPEO25) and water was studied. It was established that the probability of microemulsion formation increases with surfactant concentration. The microenviroment of the solubilization of the VAc and of silane derivatives in the aggregates of NPEO25 was affected by their polarity. Hybrid materials were obtained by sol-gel reaction of silane derivatives combined with free-radical polymerization of VAc. The change of the glass transition temperature and of thermal stability of the polymer chains in the presence of the inorganic one proved the formation of simultaneous polymer inorganic hybrids. 相似文献
25.
Ana-Maria Matache;Tobias Von Petersdorff;Christoph Schwab 《Mathematical Modelling and Numerical Analysis》2004,38(1):37-71
Arbitrage-free prices u of European contracts on risky assets whoselog-returns are modelled by Lévy processes satisfya parabolic partial integro-differential equation (PIDE) .This PIDE is localized tobounded domains and the error due to this localization isestimated. The localized PIDE is discretized by theθ -scheme in time and a wavelet Galerkin method with N degrees of freedom in log-price space. The dense matrix for can be replaced by a sparse matrix in the wavelet basis, and the linear systemsin each implicit time step are solved approximativelywith GMRES in linear complexity. The total work of the algorithm for M time steps is bounded byO(MN( log(N))2) operations and O(N log(N)) memory.The deterministic algorithm gives optimal convergence rates (up to logarithmic terms) for the computed solutionin the same complexity as finite difference approximationsof the standard Black–Scholes equation.Computational examples for various Lévy price processes are presented.https://doi.org/10.1051/m2an:2004003 相似文献
26.
D.D. Udrea P.J. Bryanston-Cross W.K. Lee M. Funes-Gallanzi 《Optics & Laser Technology》1996,28(5):389-396
This article presents two algorithms for spatial processing of low seeding density PIV (particle image velocimetry) images which lead to sub-pixel precision in particle positioning. The particle centres are estimated to accuracies of the order of 0.1 pixel, yielding 1% error in velocity calculation. The first algorithm discriminates valid particles from the rest of the image and determines their centres in Cartesian coordinates by using a two-dimensional Gaussian fit. The second algorithm performs local correlation between particle pairs and determines instantaneous two-dimensional velocities. The methods have been applied initially to simulated data. Gaussian noise and distortion has then been added to simulate experimental conditions. It is shown that, in comparison with conventional methods, the new algorithms offer up to an order of magnitude higher accuracy for particle centre estimation. Finally, the Gaussian fit approach has been used to map an experimental transonic flow field from the stator trailing edge wake region of a cascade with an estimated error of 1%. The experimental results are found to be in good agreement with previous theoretical steady-state viscous calculations. 相似文献
27.
Adrian Eugen Rosca Mara Ioana Iesanu Carmen Denise Mihaela Zahiu Suzana Elena Voiculescu Alexandru Catalin Paslaru Ana-Maria Zagrean 《Molecules (Basel, Switzerland)》2020,25(23)
Capsaicin is a widespread spice known for its analgesic qualities. Although a comprehensive body of evidence suggests pleiotropic benefits of capsaicin, including anti-inflammatory, antioxidant, anti-proliferative, metabolic, or cardioprotective effects, it is frequently avoided due to reported digestive side-effects. As the gut bacterial profile is strongly linked to diet and capsaicin displays modulatory effects on gut microbiota, a new hypothesis has recently emerged about its possible applicability against widespread pathologies, such as metabolic and inflammatory diseases. The present review explores the capsaicin–microbiota crosstalk and capsaicin effect on dysbiosis, and illustrates the intimate mechanisms that underlie its action in preventing the onset or development of pathologies like obesity, diabetes, or inflammatory bowel diseases. A possible antimicrobial property of capsaicin, mediated by the beneficial alteration of microbiota, is also discussed. However, as data are coming mostly from experimental models, caution is needed in translating these findings to humans. 相似文献
28.
Kevin Bold Dr. Matthias Stolte Dr. Kazutaka Shoyama Ana-Maria Krause Alexander Schmiedel Dr. Marco Holzapfel Prof. Christoph Lambert Prof. Frank Würthner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(30):e202200355
A series of donor-acceptor (D−A) macrocyclic dyads consisting of an electron-poor perylene bisimide (PBI) π-scaffold bridged with electron-rich α-oligothiophenes bearing four, five, six and seven thiophene units between the two phenyl-imide substituents has been synthesized and characterized by steady-state UV/Vis absorption and fluorescence spectroscopy, cyclic and differential pulse voltammetry as well as transient absorption spectroscopy. Tying the oligothiophene strands in a conformationally fixed macrocyclic arrangement leads to a more rigid π-scaffold with vibronic fine structure in the respective absorption spectra. Electrochemical analysis disclosed charged state properties in solution which are strongly dependent on the degree of rigidification within the individual macrocycle. Investigation of the excited state dynamics revealed an oligothiophene bridge size-dependent fast charge transfer process for the macrocyclic dyads upon PBI subunit excitation. 相似文献
29.
Aurica Farcas;Khaleel I. Assaf;Ana-Maria Resmerita;Liviu Sacarescu;Mihai Asandulesa;Pierre-Henri Aubert;Werner M. Nau; 《European journal of organic chemistry》2019,2019(21):3442-3450
The effect of cucurbit[7]uril (CB7) complexation on the solubility, thermal, optical, electrochemical, morphological, and electrical properties of poly(3,4-ethylenedioxythiophene) (PEDOT) was investigated. For this purpose, PEDOT polypseudorotaxane (PEDOT·CB7-PS) was synthesized by the chemical oxidation of the corresponding 3,4-ethylenedioxythiophene (EDOT) inclusion complex with CB7 (EDOT·CB7) in water by using FeCl3 as catalyst. PEDOT·CB7-PS is converted into the polyrotaxane (PEDOT·CB7-PR) by end capping of the PEDOT backbones with bulky pyrene groups. The binding affinity (Ka = 1.5 × 104 m–1) confirmed sizeable binding of EDOT to CB7. FT-IR, 1H NMR, ESI-MS, and DFT calculations were used to characterize the synthesized compounds. PEDOT·CB7-PR showed interesting electrochemical characteristics, which are consistent with the optical and surface-morphological results. In particular, the material exhibited n- and p-doping processes and semiconducting properties. SAXS and TEM analyses of PEDOT·CB7-PR indicated a tendency to self-assemble. 相似文献
30.
Berberich M Krause AM Orlandi M Scandola F Würthner F 《Angewandte Chemie (International ed. in English)》2008,47(35):6616-6619