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101.
In this article, we analyze the effect of the alcohol content in gasoline on the permeability of four semicrystalline polymers used in automobile fuel systems. More specifically, we are interested in the methanol/toluene mixture as a “binary” model of a complex gasoline to understand the selectivity brought about, in front of these solvents, by the nature of the polymer. We developed a permeation cell coupled to a chromatograph to analyze the composition of escaping toluene and methanol. These experiments allow us to demonstrate the strong “positive synergy” that exists between the flows of the methanol and the toluene when they are mixed, compared to the flows of these solvents on their own. This phenomenon is notably highlighted on polymers of very different kinds (PA12, PVDF, HDPE, EVOH) and, in light of recent theoretical developments, we can consider that this property is general, because this “positive synergy” is a consequence of the evolution of the solubility of the mixture of solvents in the polymer film, and more particularly, of the highly positive value of the Flory‐Huggins interaction coefficient between methanol and toluene. These experimental data allow one to better understand and predict the permeability behavior of the polymers in front of complex gasolines. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2727–2733, 2003 相似文献
102.
103.
Florence Chantraine Marylene Viana Nelly Brielles Olivier Mondain-Monval Christelle Pouget Paul Branlard Gilles Rubinstenn Dominique Chulia 《Journal of Porous Materials》2008,15(3):277-287
The functional characteristics (mechanical strength, disintegration and dissolution times) of effervescent detergent tablets
containing chlorine provider were investigated according to the presence of a surfactant, sodium dodecyl sulphate (SDS). Tablets
were compared for similar total porosity. The end-use property study highlighted that the presence of 2% of sodium dodecyl
sulphate was not favorable to the tablet mechanical characteristics, inducing a lower “bonding ability”. The linear relationship
between the disintegration and dissolution times showed that the disintegration time was relevant to express the behavior
of the tablets in water. The disintegration data showed two zones: when porosity was higher than 20%, the disintegration time
was always lower than 2 min g−1 and similar for both formulas; for lower porosities, the disintegration time increased and was higher in the presence of
the surfactant. In this second case, the released CO2 due to the reaction between adipic acid and sodium bicarbonate in water was slowed down in the presence of the surfactant,
confirming the disintegration data. However, this negative effect of SDS on the disintegration time could not be linked to
a difference of pore size distribution between the two formulas. So, despite the creation of weak interparticle bonds with
the other compounds of the formula, the presence of SDS increased the disintegration by limiting the water uptake, independently
of the porous texture. Moreover, no preferential localization of the surfactant at the surface of the tablet might be involved
to explain the effect of SDS on the tablet accessibility by water. 相似文献
104.
We demonstrate high-fidelity guidance of axons using rows of nanowires. The axons are prevented from crossing the rows, making it possible to guide and sort a large number of axons as opposed to when chemical patterns are used. Focal adhesion forms at the nanowires establishing a possible site of information transfer between the surface and the cells. Rows of gallium phosphide (GaP) nanowires were epitaxially grown on GaP(111) substrates in patterns defined by electron beam lithography. 相似文献
105.
Sylvain Deville Jérôme Chevalier Christelle Dauvergne Gilbert Fantozzi José F. Bartolomé José S. Moya Ramón Torrecillas 《Journal of the American Ceramic Society》2005,88(5):1273-1280
The low-temperature autoclave aging behavior of zirconia-toughened alumina composites processed by a classical powder mixing processing route was analyzed using atomic force microscopy (AFM), scanning electron microscopy, and X-ray diffraction (XRD). The transformation was evaluated in terms of nucleation and growth, assessed by XRD. The time–temperature equivalency of the transformation was used to measure an apparent activation energy of the nucleation stage of the transformation of 78 kJ/mol. The microstructural features influencing the transformation were identified, and the influence of the alumina matrix on the transformation was investigated. Transformation progression grain by grain was observed by AFM. Transformation does not only occur in zirconia agglomerates but also in isolated zirconia grains. The matrix could partially inhibit the transformation. This behavior could be rationalized considering the constraining effect of the alumina matrix, shape strain accommodation arguments, and microstructural homogeneity effects. 相似文献
106.
1,2,3‐Triazolium‐Based Cationic Amphipathic Peptoid Oligomers Mimicking Antimicrobial Helical Peptides
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Dr. Radhe Shyam Nicolas Charbonnel Aurélie Job Christelle Blavignac Prof. Dr. Christiane Forestier Prof. Dr. Claude Taillefumier Dr. Sophie Faure 《ChemMedChem》2018,13(15):1513-1516
Amphipathic cationic peptoids (N‐substituted glycine oligomers) represent a promising class of antimicrobial peptide mimics. The aim of this study is to explore the potential of the triazolium group as a cationic moiety and helix inducer to develop potent antimicrobial helical peptoids. Herein we report the first solid‐phase synthesis of peptoid oligomers incorporating 1,2,3‐triazolium‐type side chains and their evaluation against Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus. Several triazolium‐based oligomers, even of short length, selectively kill bacteria over mammalian cells. SEM visualization of S. aureus cells treated with a dodecamer and a hexamer reveals severe cell membrane damage and suggests that the longer oligomer acts by pore formation. 相似文献
107.
Marie-Laure Fontaine Christelle Denonville Zuoan Li Wen Xing Jonathan M. Polfus Jannicke Kvello Joachim Seland Graff Paul Inge Dahl Partow P. Henriksen Rune Bredesen 《Journal of the European Ceramic Society》2018,38(4):1695-1701
Novel asymmetric hydrogen permeable membranes consist of a dense ceramic–ceramic (cercer) composite layer of La0.87Sr0.13CrO3-δ and La27W3.5Mo1.5O55.5-δ deposited on a tubular porous support of the latter composition. The membranes were produced by extrusion and dip-coating with various thermal cycles required for adjusting the thermal shrinkage of the different layers and obtaining gas tight membrane layers. The produced asymmetric membranes have a dense cercer layer thicknesses ranging from 25 to 50 μm on supports exhibiting a porosity of up to 40 vol%. The effect of processing parameters, such as volume of pore former, coating steps, sintering temperature and soaking time on the microstructure of the membranes is discussed to highlight critical steps in the manufacturing protocol. Hydrogen fluxes were measured as a function of temperature with both wet and dry Ar sweep gas. Results are discussed with respect to membrane architectures and materials properties. 相似文献
108.
Sarah Temmam Bernard Davoust Jean-Michel Berenger Didier Raoult Christelle Desnues 《International journal of molecular sciences》2014,15(6):10377-10397
Many human viral infections have a zoonotic, i.e., wild or domestic animal, origin. Several zoonotic viruses are transmitted to humans directly via contact with an animal or indirectly via exposure to the urine or feces of infected animals or the bite of a bloodsucking arthropod. If a virus is able to adapt and replicate in its new human host, human-to-human transmissions may occur, possibly resulting in an epidemic, such as the A/H1N1 flu pandemic in 2009. Thus, predicting emerging zoonotic infections is an important challenge for public health officials in the coming decades. The recent development of viral metagenomics, i.e., the characterization of the complete viral diversity isolated from an organism or an environment using high-throughput sequencing technologies, is promising for the surveillance of such diseases and can be accomplished by analyzing the viromes of selected animals and arthropods that are closely in contact with humans. In this review, we summarize our current knowledge of viral diversity within such animals (in particular blood-feeding arthropods, wildlife and domestic animals) using metagenomics and present its possible future application for the surveillance of zoonotic and arboviral diseases. 相似文献
109.
Fidèle Paul Tchobo Guy Alain Alitonou Mohamed Mansourou Soumanou Bruno Barea Christelle Bayrasy Mickaël Laguerre Jérôme Lecomte Pierre Villeneuve K. C. Dominique Souhounhloue 《Journal of the American Oil Chemists' Society》2014,91(3):471-479
Essential oils with antioxidant properties are of increasing interest in West Africa where there are many antioxidant rich plants. The objective of this study was to determine the essential oil extracted from six native plants (Lippia multiflora, Lippia rugosa, Monodora tenuifolia, Ocimum gratissimum, Pimenta racemosa, Cymbopogon citratus) extracted by hydrodistillation from local plants in Benin. These samples were also evaluated for their antioxidant capacity using the conjugated autoxidizable triene (CAT) assay performed in stripped tung oil-in-water emulsion. The essential oil of P. racemosa, containing high amounts of chavicol (10.3 %) and eugenol (54.5 %), showed the strongest antioxidant activity, followed by that from O. gratissimum containing large amounts of thymol (50.2 %). The essential oil extracted from M. tenuifolia exhibited a moderate antioxidant activity. This essential oil is primarily composed of sesquiterpene alcohols such as α-cadinol (20.5 %), its isomer, α-muurolol (14.7 %), and germacrene D-4-ol (16.8 %). Essential oils from L. multiflora, L. rugosa and C. citratus oils showed poor ability to protect tung oil from oxidation. Finally, essential oils containing phenolic compounds and, in a lesser extent, sesquiterpene alcohols, exhibited the highest CAT values indicating that these compounds are the key determinants of the antioxidant activity of these essential oils in oil-in-water emulsions. 相似文献
110.
The water sorption and solubility parameters of chemically active paints were studied by electrochemical impedance spectrometry (EIS) measurements. Erodible acrylic-based coatings containing biocidal tertiary amines were investigated. Results from EIS measurements show that both the water sorption at saturation and the apparent water diffusion coefficient decrease as the alkyl chain length of the biocidal amines increases from 8 to 16 carbon atoms. The increase of the hydrophobic character of the resulting coatings results to a higher resistance to erosion. Erosion tests performed under static and dynamic conditions show that the seawater conditions can markedly affect the performance of chemically active paints. 相似文献