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1.
The excess molar enthalpy of ternary mixture for 3-diethylaminopropylamine+heptane+cyclohexane were measured using a Calvet microcalorimeter at 303.15 K. Empirical equations, Redlich-Kister, Tsao-Smith, and Kohler and group contribution models, UNIFAC (modified version) and DISQUAC have been applied. A reasonable representation of ternary data is obtained. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
2.
Mercier X  Pillier L  el Bakali A  Carlier M  Pauwels JF  Desgroux P 《Faraday discussions》2001,(119):305-19; discussion 353-70
NO reburning is studied in a low pressure (15 hPa) premixed flame of CH4-O2 seeded with 1.8% of NO. Measurements were carried out by using cavity ring-down spectroscopy (CRDS) and laser induced fluorescence (LIF) techniques. The temperature profile was obtained by OH-LIF thermometry in the A-X (0-0) band. The OH profile was determined by LIF and calibrated by single pass absorption. The NO concentration profile was obtained by LIF in the A-X (0-0) band and corrected for Boltzmann fraction and quantum yield variations. The absolute concentration profile was determined in the burned gases by CRDS allowing a direct experimental determination of the NO reburning amount. Finally CH and CN mole fraction profiles were obtained by CRDS by exciting rotational transitions in the B-X (0-0) bands of CH and CN around 387 nm. We found a peak mole fraction of 29 ppm for CH and 3.3 ppm for CN. This last result is in contrast with a previous study of W. Juchmann, H. Latzel, D. L. Shin, G. Peiter, T. Dreier, H. R. Volpp, J. Wolfrum, R. P. Lindstedt and K. M. Leung, XXVIIth Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, 1998, p. 469, performed in a similar flame, which reported much lower levels of CN. In that study the absolute concentration of CN was indirectly obtained by LIF calibrated by Rayleigh scattering. In a second part, experimental species profiles are compared with predictions of the GRI 3.0 mechanism. Comparison between experimental and predicted profiles shows a good agreement particularly for CN and NO species. A qualitative analysis of NO reburning is then performed.  相似文献   
3.
Cellulose - Enhancing the sorption properties of cellulose is a prerequisite for its efficient use in water purification as an alternative to costly activated carbon. Here, solvent-free...  相似文献   
4.
Three selective CB2 cannabinoid receptor ligands have recently been discovered to be promising anti-inflammatory agents but their low water solubility hinder their per os administration. The popularity of the cyclodextrins, from a pharmaceutical standpoint lies on their ability to interact with poorly water-soluble drugs and improve their solubility. Herein, three experimental approaches for calculating the stability constant of complexes between the selective CB2 ligands and either the β-CD or the HP-β-CD, were tested: nuclear magnetic resonance, micellar electrokinetic chromatography and high performance liquid chromatography in reversed phase. In NMR studies the calculated K values were relatively high and were between 1486 and 3571 M?1 with β-CD. With HP-β-CD they were between 1203 and 2650 M?1. Concerning the two others techniques the K values were found lower. In MECK studies with β-CD they were between 308 and 792 M?1 and with HP-β-CD between 124 and 764 M?1. Finally in RP-HPLC studies with β-CD, they were between 539 and 1144 M?1 and with HP-β-CD between 196 and 396 M?1. These calculated constants suggest that a complexation phenomenon occurs. A model for inclusion of one of the CB2 ligands in the β-CD was then proposed from molecular modeling studies.  相似文献   
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6.
After studying Gaussian type quadrature formulae with mixed boundary conditions, we suggest a fast algorithm for computing their nodes and weights. It is shown that the latter are computed in the same manner as in the theory of the classical Gauss quadrature formulae. In fact, all nodes and weights are again computed as eigenvalues and eigenvectors of a real symmetric tridiagonal matrix. Hence, we can adapt existing procedures for generating such quadrature formulae. Comparative results with various methods now in use are given. In the second part of this paper, new algorithms for spectral approximations for second-order elliptic problems are derived. The key to the efficiency of our algorithms is to find an appropriate spectral approximation by using the most accurate quadrature formula, which takes the boundary conditions into account in such a way that the resulting discrete system has a diagonal mass matrix. Hence, our algorithms can be used to introduce explicit resolutions for the time-dependent problems. This is the so-called lumped mass method. The performance of the approach is illustrated with several numerical examples in one and two space dimensions.

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7.
The viscoelastic behavior of low molecular weight polymers exhibiting a fairly broad distribution has been deduced from the behavior of narrow samples by way of a linear law as a function of the density of the molecular weight distribution. Rheology of polydisperse linear polymers where the entire distribution of molecular weights is lower than 2 M ehas been investigated using both binary mixtures and a broad sample of polystyrene. A decrease of the friction coefficient and of the viscosity compared to that of a narrow sample with the same M w is observed. Therefore, the low components of broad samples play the role of plasticizers or lubricants which has been investigated in relation with the molecular weight distribution.  相似文献   
8.
In this paper, we introduce a notion of similarly self dual lattice in a d-dimensional Euclidean space and a classical Jacobi theta function is associated to such a lattice. We establish identities of arithmetic type between values of this theta function and its successive derivatives. This work can be related to the spectral theory of the Landau operators.   相似文献   
9.
We provide two kinds of representations for the Taylor coefficients of the Weierstrass σ-function σ(?;Γ) associated to an arbitrary lattice Γ in the complex plane \(\mathbb{C}=\mathbb{R}^{2}\) , the first one in terms of the so-called Hermite–Gauss series over Γ and the second one in terms of Hermite–Gauss integrals over \(\mathbb{C}\) .  相似文献   
10.
Let Ω⊂ℝ d be a compact convex polytope of positive measure. We study cubature formulae on Ω which approximate the integral of every convex function fC(Ω) from above. They are called negative definite formulae or nd-formulae for short. In particular, we characterize nd-formulae by certain partitions of unity or, alternatively, by a class of positive linear operators. For aiming at ‘good’ nd-formulae, we introduce three extremal properties named as minimal, best and optimal. We show that the Delaunay triangulation and one of its generalizations give access to efficient algorithms for computing nd-formulae with one of these properties.  相似文献   
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