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11.
Christine Bressy Minh Ngoc NGuyen Brigitte Tanguy Van Giang Ngo André Margaillan 《Polymer Degradation and Stability》2010,95(7):1260-9117
Polymers containing hydrolytically labile trialkylsilyl ester side groups were synthesised via a conventional and a controlled radical polymerization. The trialkylsilyl methacrylate monomer unit was chosen for its capacity to hydrolyse into basic, acid or sea water varying the hydrophilic character of the resulting polymer backbone with time. The hydrolysis or saponification reaction of the ester bond of the trialkylsilyl methacrylate was monitored through a 1H NMR study showing the formation of siloxane side-products. Several copolymers and polymer blends were prepared as matrixes for controlled erodible systems. Their capacity to hydrolyse was demonstrated through SEM investigations with selective dissolution of free films containing hydrolysable copolymers and PMMA blends. Well-defined random and diblock copolymers with methyl methacrylate were investigated to show the effect of the microstructure on the erosion properties of the corresponding coatings. Poly(methyl methacrylate-b-tert-butyldimethylsilyl methacrylate) diblock copolymers synthesised through the RAFT process showed a better control of the erosion with a constant erosion rate over a long-time service in sea water at pH = 8.2. In addition, experiments showed that the erosion rate could be modulated by varying the molar proportion of hydrolysable side groups onto the copolymer backbone and the weight amount of copolymers mixed with PMMA in toluene solution. 相似文献
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An experimental and numerical investigation into the magnitude of longitudinal and transverse dispersion in a two-dimensional flow field over a particle Peclet number range of 50–8500 is reported. Numerical modelling using a Galerkin finite element method is used to test various models, notably those of Fried and combarnous and Koch and Brady. Dispersion at low Peclet numbers (< 200) is found to be described adequately by either model, which at large Peclet, the degree of dispersion is significantly underestimated. An improved dispersion model for Peclet numbers greater than 200 is proposed. The transverse dispersion term and the choice of inlet boundary condition are found to have a negligible effect on the shape of the breakthrough curve.Nomenclature
A (z)
Polynomial in the z plane
-
B (z)
Polynomial in the z plane
-
C
Concentration
-
C
f
Feed concentration
-
C
o
Concentration at the entrance
-
D
Dispersion tensor
-
D
f
Molecular diffusion coefficient
-
D
1
Longitudinal dispersion coefficient
-
D
p
Particle diameter
-
D
t
Transverse dispersion coefficient
-
k
Permeability/viscosity
-
k
Dimensionless permiability in the Koch and Brady model
-
P
Pressure
- Pe
k
Modified Peclet number, Pe
p
k
- Pe
p
Particle Peclet number vD
p
/D
f
-
v
Velocity
-
z
Axial coordinate or complex variable
Greek letters
Solution domain
-
Boundary
-
Porosity 相似文献
15.
G. Charlot J. Badoz-Lambling P. Homsi V. Plichon J.P. Saget A. Kerouanton 《Journal of Electroanalytical Chemistry》1977,75(2):665-675
Results obtained by electrochemistry in molten cryolite and sodium tetrafluoroaluminate are related to the following points: self-dissociation constant of the melts, classification of fluoride-ion donors/acceptors, electrooxidation of so-called “dissolved” aluminium, anode effect, redox behaviour of phosphorous (V), boron (III+), and some metals, titration of alumina by CrF3. 相似文献
16.
We study the influence of the spatial extension of the electron-hole plasma created by a pump pulse on the reflectivity of a probe pulse. We show that the density deduced from reflectivity measurements is the surface density value with a very good accuracy, except very close to the plasma resonance. We also show that the resonance broadening due to the spatial inhomogeneity can be larger than the one due to free carriers absorption and has to be included in the usual experimental determination of the plasma relaxation time. 相似文献
17.
In a two-phase system (saturated aqueous calcium hydroxide, tetrabutylamnonium sulfate, dichloromethane, iron pentacarbonyl) benzyl bromides are readily carbonylated to dibenzyl ketones; α-α′ dibromoorthoxylene yields the o-quinodimethane iron tricarbonyl complex 8. It is inferred that the reactions proceed through transient generation of the tetracarbonyl ferrate dianion. 相似文献
18.
Tanguy Briançon Mohammed Hayouni Michel Pierre 《Calculus of Variations and Partial Differential Equations》2005,23(1):13-32
We prove local Lipschitz continuity of the solution to the state equation in two kinds of shape optimization problems with constraint on the volume: the minimal shaping for the Dirichlet energy, with no sign condition on the state function, and the minimal shaping for the first eigenvalue of the Laplacian. This is a main first step for proving regularity of the optimal shapes themselves.Received: 11 November 2003, Accepted: 10 May 2004, Published online: 8 February 2005Mathematics Subject Classification (2000):
49Q10, 35R35, 49K20, 35J20 相似文献
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20.
Tanguy Pier Khalid Kandoussi Claude Simon Nathalie Coulon Tayeb Mohammed-Brahim Hervé Lhermite 《Journal of Non》2008,354(19-25):2300-2304
Microcrystalline silicon (μc-Si) films have been deposited on PDMS as well as on PEN substrate. Excimer laser annealing was used to improve the crystalline structure and so to obtain high mobility TFTs. The effect of the laser annealing on the crystalline structure of silicon films is studied using different characterization techniques and discussed. Mobility values of 60 cm2/V s with PDMS and 46 cm2/V s with PEN are obtained. 相似文献