Determination of the surface energy of kaolinite and serpentine using PACHA formalism-comparison with immersion experiments

Clays play an important role in a wide variety of industrial processes. Indeed, they present interesting surface properties. For these reasons, we study the surface energy of models of clays by solid state calculations using electronegativities equalization. In this article, we focus on kaolinite and serpentine, two clays characterized by a simple structure of the TO type. We describe the clays and their structures and we develop a simple model from solid state calculations used to determine the surface energy. The results are in agreement with a recent interpretation of the immersion of kaolinite in water. This article must be related to some others focusing on solid surface energy, especially some treating talc and chlorites, and montmorillonites saturated by alkaline cations, to be published.     

Resolvent Estimates for the Laplacian on Asymptotically Hyperbolic Manifolds

Combining results of Cardoso-Vodev [6] and Froese-Hislop [9], we use Mourre’s theory to prove high energy estimates for the boundary values of the weighted resolvent of the Laplacian on an asymptotically hyperbolic manifold. We derive estimates involving a class of pseudo-differential weights which are more natural in the asymptotically hyperbolic geometry than the weights used in [6]. submitted 28/04/05, accepted 26/09/05     

Transient isotachophoresis in carrier ampholyte-based capillary electrophoresis for protein analysis

Transient ITP (t-ITP) has been used in carrier ampholyte-based CE (CABCE) to enhance the sensitivity of protein analysis. The characteristics of carrier ampholytes (CAs) narrow pH cuts-based buffers, when used as BGEs in CE are compatible with t-ITP requirements. Indeed, being the sole buffering species of such solutions, CAs impose a pH close to their pI. Thus, in these solutions, the CAs possess low electrophoretic mobility. As a consequence, by adding an ionic component with high electrophoretic mobility either in the studied sample or in the BGE, a t-ITP step can be generated. This has first been demonstrated for protein test mixtures. Then, the combination of t-ITP with CABCE has been applied to study a real sample, the bovine milk.     

Communication: thermodynamic signatures of cluster formation in fluids with competing interactions

Convergent theoretical evidence, based on self-consistent integral equations for the pair structure and on Monte Carlo simulations, is presented for the existence of small simultaneous jump discontinuities of several thermodynamic and structural properties of systems of colloidal particles with competing short-range attractive and long-range repulsive interactions, under physical conditions close to the onset of particle clustering. The discontinuities thus provide a signature of the transition from a homogeneous fluid phase to a locally inhomogeneous cluster phase.     

Response to "Comments on 'A field study of the exposure-annoyance relationship of military shooting noise' " [J. Acoust. Soc. Am. 127, 2301-2311 (2010)] (L)

This letter is a response to Meyer's recent paper ["Comment on 'A field study of the exposure-annoyance relationship of military shooting noise,' "J. Acoust. Soc. Am. 130, 677-678 (2011)]. The authors describe that "explained variance" in noise annoyance surveys can mean different things and that the fit parameters of the statistical models reported in the commented article are well within an expectable range. It is discussed that non-dose-related factors for the prediction of noise annoyance have become increasingly important in the last years and deserve to be more thoroughly studied.     

Laser ultrasonics detection of an embedded crack in a composite spherical particle

Laser ultrasonics was applied to the manufacturing control of the integrity (no failure) of coated spherical particles designed for High Temperature Reactors (HTR). This control is of major importance, since the coating of the nuclear fuel kernel is designed to prevent from the diffusion of fission products outside the particle during reactor operation. The SiC layer composing the coating is particularly important, since this layer must be an impenetrable barrier for fission products. The integrity of the SiC shell (no crack within the shell) can be assessed by the ultrasonic vibration spectrum of the HTR particle, which is significantly changed, compared to the reference spectrum of a defect-free particle. Spheroidal vibration modes of defect-free dummy particles with a zirconium dioxide (ZrO₂) core were observed in the 2-5 MHz range. A theoretical analysis is presented to account for the observed vibration spectra of defect-free or cracked HTR particles.     

The ν1 and ν1 + ν2 − ν2 infrared absorption bands of H12CP

The vibration-rotation spectrum of HCP was recorded in the region of the ν₁ band with a resolution of about 0.035 cm^?1. All the data available were combined to calculate spectroscopic constants for the 00⁰0, 10⁰0, 01^1e0, 01^1f0, 11^1e0, and 11^1f0 states.     

On ∑-lossless transfer functions and related questions

This paper is concerned with a systematic approach to the properties of ∑-lossless rational transfer functions in the discrete as well as in the continuous time case. As a result, a unifying framework is revealed where several known results fit naturally. Special attention is given to the embedding problem of the Lyapunov equation in view of its direct application to generalized Levinson algorithms.     

Pseudo-nucléosides dérivés des pyrrolo[2, 3-d]pyrimidines. Synthèse et activité biologique

A new series of pseudonucleosides has been obtained by condensation of various aminopentopyranoses on a 4,6-dichloro-5-acetonylpyrimidine. Cyclisation into pyrrolo[2,3-d] pyrimidine leads in one step to new tubercidin analogs. Some of them exhibit significant antiviral activity toward vaccinia virus and Sindbis virus.     

Molecular weight segregation induced by interfacial melt reactivity in polyamide 6/reactive rubber blends

Polyamide 6 (PA) and ethylene-propylene rubber with maleic functionality (EPMA) were blended in a batch mixer. EPMA anhydride groups react with amine chain ends of polyamide and form a grafted copolymer at the interface. The molecular weights of the grafted PA and of the free PA were measured. The molecular weight of the free PA decreases during the processing. This effect is due to the hydrolysis of the PA consecutively to its reaction with anhydride groups. The molecular weight of both grafted and free polyamide decreases during the processing. Moreover, the molecular weight of the grafted PA is lower than that of the free PA. At constant mixing time, a high conversion level produces grafted PA with a higher molecular weight. This is the result of molecular weight segregation for interfacial reaction. Small molecules react faster at the interface than larger ones. If we compare experimental results with model predictions, two segregation regimes are observed. For high shear and low EPMA concentrations, dispersion is very fast; the segregation only depends on molecular elasticity. In this case, the best correlation between model and experiment is obtained for low interfacial thicknesses. For low shear, or for EPMA concentrations close to the phase inversion composition, the segregation is more noticeable, which is mainly due to the diffusion of macromolecules through the brush of already grafted molecules. In this case, there is a clear competition between the compatibilization and the grafting reaction. Molecular weight segregation gives low ratio of the grafted PA molecular weight to the free PA molecular weight. This is detrimental to interfacial properties of the grafted copolymer formed by melt reactivity. Strategies are developed to improve this ratio in order to investigate its influence on the mechanical properties. © 1995 John Wiley & Sons, Inc.