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61.
62.
The structure and dynamics at the interface of swelling clays (smectites) are crucial to such diverse applications as drilling for oil, cosmetics, paints, water treatment, or chemical reactions. From our previous NMR studies on clay suspensions, we have shown how the orientation of interfacial molecules is affected by the clay structure1, by the nature of counterions 2, or by the composition of the liquid phase3. These results have been mainly obtained from the analysis of residual quadrupolar splittings of nuclei from interfacial species. In this work, we report our studies on a clay montmorillonite suspended in aqueous solutions of non ionic polymers. The polymer perturbs the structure within the interfacial region as deduced from the variations of the splittings of water quadrupolar nuclei and of sodium-23 relaxation parameters in terms of the polymer concentration. Proton self-diffusion coefficients and carbon-13 relaxation times are measured to describe the influence of the clay on the polymer mobility. The dependence of the polymer nature on these parameters is also investigated. 相似文献
63.
64.
M. de Billy F. Cohen-Ténoudji Gérard Quentin Kent Lewis Laszlo Adler 《Journal of Nondestructive Evaluation》1980,1(4):249-261
Ultrasonic measurements from rough cracks were carried out using both broad-band and narrow-band methods. An analysis is suggested to determine parameters of the crack quantitatively such as size, shape, rms surface roughness, and distribution function of the surface roughness. Ultrasonic measurements of the parameters compare very well with the actual parameters of the defect. 相似文献
65.
Laszlo Tepliczky 《Forschung im Ingenieurwesen》1970,36(3):74-78
Zusammenfassung Drei der bedeutendsten Verfahren zum Berechnen des Wirbelkernhalbmessers in rotationssymmetrischen Drallstr?mungen werden
miteinander verglichen. Zwar liegt jedem dieser Verfahren eine Energieberechnung zugrunde; die Ergebnisse unterscheiden sich
jedoch erheblich voneinander. Es wird die Ursache jener Abweichungen untersucht und festgestellt, da? das von K. Bammert vorgeschlagene
Verfahren nur mit Berücksichtigung der Volumflu?verteilung die gleichen Ergebnisse wie die Berechnungsverfahren von E. Meldau
und M. Strscheletzky liefert. Ferner geht aus der Untersuchung die Bedeutung der Axialgeschwindigkeitsverteilung hervor. Die
Verwendbarkeit dieser Verfahren bleibt dadurch auf jene F?lle beschr?nkt, in denen der Drall und die Axialgeschwindigkeit
in der betrachteten achsnormalen Ebene konstant sind. 相似文献
66.
An automatic quadrature algorithm especially designed for double integration of functions with some form of singular behaviour on the boundary of the integration region is described, and its FORTRAN code is presented. The algorithm is based on the use of the product trapezoidal rule, after a non-linear transformation of the integrand in both variables renders a new integrand function whose derivatives vanish on the (transformed) boundary. Numerical results demonstrate the ability of the algorithm to obtain high accuracies in dealing automatically with pathological singularities of non-specific types. 相似文献
67.
Data are given for shear and tensile testing of adhesive bonds under conditions of a constant rate of loading. A rate equation is then used to predict lifetime from the mechanical data. The correlations appear to be satisfactory providing that the failure is cohesive within the adhesive. 相似文献
68.
Elise E. Switzer Tim S. Olson Plamen Atanassov Christopher J. Cornelius 《Electrochimica acta》2009,54(3):989-8003
In this work, we have investigated an aerosol-derived templated electrocatalyst for electro-oxidation of small organic molecules in alkaline media. Templated Pt-Sn electrocatalysts are compared to templated Pt catalysts both synthesized in an aerosol synthesis technique. In this synthesis approach, mono-disperse silica nanoparticles are used to template the metallic precursors. Structural and compositional analysis of the nanostructured materials are performed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and BET surface area measurements. The aerosol-derived templated electrocatalysts are examined in conjunction with an anion exchange ionomer for ethanol, methanol and CO oxidation in alkaline media. The electrochemical studies include cyclic voltammetry, chronoamperometry and voltammetric adsorption of adsorbed CO. 相似文献
69.
Raundahl J Loog M Pettersen P Tanko LB Nielsen M 《IEEE transactions on medical imaging》2008,27(8):1054-1060
70.
Firmesse O Alvaro E Mogenet A Bresson JL Lemée R Le Ruyet P Bonhomme C Lambert D Andrieux C Doré J Corthier G Furet JP Rigottier-Gois L 《International journal of food microbiology》2008,125(2):176-181
The objective of this study was to determine i) if Camembert cheese micro-organisms could be detected in fecal samples after regular consumption by human subjects and ii) the consequence of this consumption on global metabolic activities of the host colonic microbiota. An open human protocol was designed where 12 healthy volunteers were included: a 2-week period of fermented products exclusion followed by a 4-weeks Camembert ingestion period where 2x40 g/day of Camembert cheese was consumed. Stools were collected from the volunteers before consumption, twice during the ingestion period (2nd and 4th week) and once after a wash out period of 2 weeks. During the consumption of Camembert cheese, high levels of Lactococcus lactis and Leuconostoc mesenteroides were measured in fecal samples using real-time quantitative PCR, reaching median values of 8.2 and 7.5 Log(10) genome equivalents/g of stool. For Ln. mesenteroides, persistence was observed 15 days after the end of Camembert consumption. The survival of Geotrichum candidum was also assessed and the fecal concentration reached a median level of 7.1 Log(10) CFU/g in stools. Except a decreasing trend of the nitrate reductase activity, no significant modification was shown in the metabolic activities during this study. 相似文献