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Plasma Chemistry and Plasma Processing - A novel direct current (DC) plasma torch, operating with a gas mixture consisting of carbon dioxide and hydrocarbon (methane), has been adapted and used for... 相似文献
23.
Folliet N Roiland C Bégu S Aubert A Mineva T Goursot A Selvaraj K Duma L Tielens F Mauri F Laurent G Bonhomme C Gervais C Babonneau F Azaïs T 《Journal of the American Chemical Society》2011,133(42):16815-16827
In the context of nanomedicine, liposils (liposomes and silica) have a strong potential for drug storage and release schemes: such materials combine the intrinsic properties of liposome (encapsulation) and silica (increased rigidity, protective coating, pH degradability). In this work, an original approach combining solid state NMR, molecular dynamics, first principles geometry optimization, and NMR parameters calculation allows the building of a precise representation of the organic/inorganic interface in liposils. {(1)H-(29)Si}(1)H and {(1)H-(31)P}(1)H Double Cross-Polarization (CP) MAS NMR experiments were implemented in order to explore the proton chemical environments around the silica and the phospholipids, respectively. Using VASP (Vienna Ab Initio Simulation Package), DFT calculations including molecular dynamics, and geometry optimization lead to the determination of energetically favorable configurations of a DPPC (dipalmitoylphosphatidylcholine) headgroup adsorbed onto a hydroxylated silica surface that corresponds to a realistic model of an amorphous silica slab. These data combined with first principles NMR parameters calculations by GIPAW (Gauge Included Projected Augmented Wave) show that the phosphate moieties are not directly interacting with silanols. The stabilization of the interface is achieved through the presence of water molecules located in-between the head groups of the phospholipids and the silica surface forming an interfacial H-bonded water layer. A detailed study of the (31)P chemical shift anisotropy (CSA) parameters allows us to interpret the local dynamics of DPPC in liposils. Finally, the VASP/solid state NMR/GIPAW combined approach can be extended to a large variety of organic-inorganic hybrid interfaces. 相似文献
24.
Claire Gervais Jaap J. Boon Federica Marone Ester S. B. Ferreira 《Applied Physics A: Materials Science & Processing》2013,111(1):31-38
The study of the early oeuvre of the Swiss painter Cuno Amiet (1868–1961) has revealed that, up to 1907, many of his grounds were hand applied and are mainly composed of chalk, bound in protein. These grounds are not only lean and absorbent, but also, as Synchrotron radiation X-ray microtomography has shown, porous. Our approach to the characterization of pore structure and quantity, their connectivity, and homogeneity is based on image segmentation and application of a clustering algorithm to high-resolution X-ray tomographic data. The issues associated with the segmentation of the different components of a ground sample based on X-ray imaging data are discussed. The approach applied to a sample taken from “Portrait of Max Leu” (1899) by Amiet revealed the presence of three sublayers within the ground with distinct porosity features, which had not been observed optically in cross-section. The upper and lower layers are highly porous with important connectivity and thus prone to water uptake/storage. The middle layer however shows low and nonconnected porosity at the resolution level of the X-ray tomography images, so that few direct water absorption paths through the entire sample exist. The potential of the method to characterize porosity and to understand moisture-related issues in paint layer degradation are discussed. 相似文献
25.
In this Letter, we give an explicit integration of some two-dimensionalised Lotka-Volterra-type equations associated with simple Lie algebras possessing a representation without branching. 相似文献
26.
Substituted benzodihydrofurans and benzodihydropyrans 2 were obtained by heating alcohol-phenols 1 in HMPA. New cyclic alkyl phenyl dimethylaminophosphoramidates 3 were also isolated. Their thermolysis was studied. This and other considerations show that bis(dimethylamino)phenol alkyl phosphorodiamidate 4 and by-product 3 are intermediates of an alternative two or threestep reaction pathway. This mechanistic study gave indications on choice of best experimental conditions for this new cyclodehydration method. 相似文献
27.
1,4 and 1,5-diols heated with 0.3 equivalent of HMPA undergo cyclodehydration leading to tetrahydrofurans and tetrahydropyrans. 相似文献
28.
Recent works of the authors on string interpretation of the Wilson loop operators in QCD are reviewed in a self-contained fashion. Although most of the results have already appeared in print, some new materials is presented on renormalization of the Wilson loop operator and on the use of light-cone expansion to derive a linear string-like equation in light-cone formalism. 相似文献
29.
The temperature dependence of the zone-center polar lattice vibrations, including a soft mode, in the cubic phase of NaNbO3 as observed by infrared reflectivity spectroscopy, is reported. Data are analysed and discussed in the light of results previously obtained in other oxidic perovskites. 相似文献
30.
We develop a method for the calculation of the expectation value of products of conformally covariant operators in the two-dimensional Liouville theory. We apply it to the evaluation of the four-point functions of the corresponding open string model, and discuss the Regge behaviour and duality properties of the result. 相似文献