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81.
Let be a Lipschitz domain and Γ be a relatively open and non-empty subset of its boundary ?Ω. We show that the solution to the linear first-order system:(1) vanishes if and . In particular, square-integrable solutions ζ of (1) with vanish. As a consequence, we prove that: is a norm if with , for some with as well as . We also give a new and different proof for the so-called ‘infinitesimal rigid displacement lemma’ in curvilinear coordinates: Let , , satisfy for some with . Then there exists a constant translation vector and a constant skew-symmetric matrix , such that . 相似文献
82.
We present some Poincaré type inequalities for quadratic matrix fields with applications e.g. in gradient plasticity or fluid dynamics. In particular, an application to the pseudostress-velocity formulation of the stationary Stokes problem is discussed. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
83.
Delphine Salort 《偏微分方程通讯》2013,38(2):209-228
We consider some linear Schrödinger equation with variable coefficients associated to a smooth symmetric metric g which can be degenerate, without sign and such that g has a submatrix of fixed rank v which is uniformly nondegenerate. In this general setting we prove Strichartz estimates with a loss of derivative on the solution. We also discuss the problem of the control of high frequencies. In particular, we prove that if the equation preserves the H s norm for all s ≥ 0, then we obtain almost the same Strichartz estimates as those for the Schrödinger equation associated to a Riemannian metric of dimension 2d ? v. 相似文献
84.
85.
Rapid Generation and Safe Use of Carbenes Enabled by a Novel Flow Protocol with In‐line IR spectroscopy 下载免费PDF全文
Simon T. R. Müller Aurélien Murat Delphine Maillos Dr. Patrick Lesimple Dr. Paul Hellier Prof. Dr. Thomas Wirth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7016-7020
A powerful new continuous process for the formation and use of donor/acceptor‐substituted carbenes is described. The safety profile of diazo group transfer on methyl phenylacetate was determined including kinetic studies in batch and in flow using in‐line IR analysis. Batch work‐up and liquid chromatography were circumvented by developing an optimized liquid/liquid flow separation method providing aryl diazoacetates in high purity. Fast screening of reaction conditions in flow with in‐line IR analysis allowed rapid reaction optimization. Finally, a multistep process of diazo group transfer, extraction, separation and subsequent diazo decomposition combined with multiple X?H insertion reactions was established. 相似文献
86.
87.
The antimicrobial peptide nisin has been observed to preferentially locate at surfaces coated with the poly[ethylene oxide]-poly[propylene oxide]-poly[ethylene oxide] (PEO-PPO-PEO) surfactant Pluronic F108, to an extent similar to its adsorption at uncoated, hydrophobic surfaces. In order to evaluate nisin function following its adsorption to surfaces presenting pendant PEO chains, the antimicrobial activity of nisin-loaded, F108-coated polystyrene microspheres and F108-coated polyurethane catheter segments was evaluated against the Gram-positive indicator strain, Pediococcus pentosaceus. The retained biological activity of these nisin-loaded layers was evaluated after incubation in the presence and absence of blood proteins, for contact periods up to one week. While an increase in serum protein concentration reduced the retained activity on both bare hydrophobic and F108-coated materials, F108-coated surfaces retained more antimicrobial activity than the uncoated surfaces. Circular dichroism spectroscopy experiments conducted with nisin in the presence of F108-coated and uncoated, silanized silica nanoparticles suggested that nisin experienced conformational rearrangement at a greater rate and to a greater extent on bare hydrophobic surfaces relative to F108-coated surfaces. These results support the notion that immobilized, pendant PEO chains confer some degree of conformational stability to nisin while also inhibiting its exchange by blood proteins. 相似文献
88.
Moinard-Chécot D Chevalier Y Briançon S Beney L Fessi H 《Journal of colloid and interface science》2008,317(2):458-468
A detailed investigation into the mechanisms of nanocapsule formation by means of the two stages "emulsion-diffusion" process is reported. Such widely used process is still poorly understood. An emulsion of oil, polymer and ethyl acetate is fabricated as a first step; dilution with pure water allows ethyl acetate to diffuse out from the droplets, leaving a suspension of nanocapsules at the end. It has been shown that the size of nanocapsules was related to the chemical composition of the organic phase and the size of primary emulsion through a simple geometrical relationship. As a consequence, most of the properties of the nanocapsules were decided at the emulsification step. The influence of several formulation and processing parameters of the primary emulsion was studied accordingly. The thin polymer membrane of nanocapsules was observed by means of cryo-fracture electron microscopy. Finally two experiments were designed for a mechanistic investigation of the diffusion step. A step-by-step diffusion of the organic solvent takes place by successive partition equilibria of ethyl acetate between the droplets and aqueous phase. A time-resolved experiment shows the fast diffusion (less than 20 ms) related to the small droplet size of the emulsion. 相似文献
89.
Carlos Jesus Muvdi Nova Delphine Paolucci-JeanjeanMarie-Pierre Belleville Mihail BarboiuMatthieu Rivallin Gilbert Rios 《Journal of membrane science》2008
A new kind of metal affinity membrane based on a ceramic support was prepared. It was elaborated in four steps: (i) deposition of a chitosan layer in order to functionalize the ceramic support, (ii) cross-linking with epichlorohydrin to stabilise the polymer layer and to enable the grafting, (iii) iminodiacetic acid grafting, (iv) Cu2+ adsorption. Due to the ceramic support, this membrane is highly resistant and the chitosan layer brings its biocompatibility properties. Each step of the membrane elaboration was studied and the membrane structure was characterized. Both thin coating of the polymer on the alumina grains of the support and the chemical modification of the membrane were proved. Then, bovine serum albumin (BSA) was used as a model protein to test protein retention of the affinity membrane. The protein/membrane interactions were investigated showing that some non-specific ones are involved. Finally, the effect of buffer concentration was checked and it appears that, in the studied range, an increase of the buffer concentration entailed a limitation of the non-specific interactions inducing a better BSA recovering and a higher selectivity. 相似文献
90.
Ha-Thi MH Penhoat M Drouin D Blanchard-Desce M Michelet V Leray I 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(19):5941-5950
A series of fluorescent phosphane oxide derivatives based on diphenylphosphanoethane (DPPE) and diphenylphosphanomethane (DPPM) skeletons has been prepared by means of Grignard reactions and Sonogashira cross-couplings. The photophysical properties and the linear and nonlinear spectra of these compounds have been investigated. An edge-to-face conformation resulting in the formation of an excimer was confirmed by fluorescence lifetime measurements of these multichromophoric derivatives. Upon complexation with heavy metal ions such as Pb2+ and Cd2+, a red shift of the one- and two-photon excitation spectra was observed in the absorption and emission spectra. Furthermore, enhancement of the electron-withdrawing character of the phosphane oxide resulted in a significant enhancement of the two-photon absorption cross-section, leading to the first biphotonic Cd2+ sensors combining high affinity for Cd2+, large two-photon absorption cross-sections, and significant enhancement of the two-photon excited fluorescence in the presence of the cation. Such derivatives are highly promising for incorporation into devices for the detection of heavy metal ions in water and effluents. 相似文献