Measurement under high pressure of the nonlinearity parameter B/A in glycerol at various temperatures

An experimental study of some assorted glycerol properties is carried out in order to determine, under high static pressure, the glycerol nonlinearity parameter B/A against temperature by a modified isentropic method. The static pressure and temperature ranges exploited in this experimental investigation, of various glycerol properties, are extended respectively from 0.1 to 100 MPa and from 10 to 100 °C. The static pressure step of two consecutive measurements is 10 MPa and the temperature step is 10 °C. The measured values show that, in glycerol, the density ρ₀ and the infinitesimal ultrasonic wave velocity c₀ increase monotonically with the imposed static pressure and decrease monotonically with temperature. The present investigation shows that the nonlinearity parameter B/A is a function of the imposed static pressure and temperature. The accuracy of the measured B/A values is estimated at about ±2%.     

Inverse determination of the heat transfer characteristics on a circular plane fin in a finned-tube bundle

In this work, we present the numerical results of the average heat transfer coefficients, $ \overline{{h_{\varphi } }} $ , over a circular plane fin in a finned-tube bundle for both aligned and staggered arrangements as well as the fin efficiency and the heat flux dissipated from the whole fin. The study covers a wide range of Reynolds number (2 × 10³–3 × 10⁴), for three different positions of the finned tube inside the heat exchanger. The temperature distribution on the fins surfaces was obtained experimentally using infrared thermography technique. The predicted values of the heat transfer coefficient were obtained numerically using the finite element method in conjunction with the conjugate gradient algorithm and the measured temperatures.     

Study of the attachment of Na+ on glucose and on some of its methylated derivatives

The mechanism of attachment of Na(+) on glucose, methyl-alpha-D-glucose, methyl-beta-D-glucose, 3-O-methylglucose, tetra-O-methylglucose, and also on galactose and methyl-beta-D-galactose, was studied. For this we measured the ion yields for the complex [sugar-Na(+)] formed by ionisation by matrix-assisted laser desorption/ionisation (MALDI) and ionspray. These data were compared with the relative volatilities and hydrophobicities of the sugars, measured by evaporative light scattering and reversed-phase liquid chromatography, respectively. Some formation enthalpies for the complexes [sugar-Na(+)], starting from the sugar and the cation, were obtained by ab initio calculations. No simple correlations could be observed between the ion yields and the parameters studied, so that the cationisation mechanism of the sugars remains unclear.     

Spectre de A(\̄gW) pour des domaines bornés faiblement pseudoconvexes réguliers

If Ω is a weakly pseudoconvex domain in a Stein manifold, then the spectrum of the Frechet Algebra $\text{A}{}^{\mathrm{\infty }}\text{(}\text{}\text{?}\text{gW)}$ is isomorphic to $\text{}\text{?}\text{gW, A}{}^{\mathrm{\infty }}\text{(}\text{}\text{?}\text{gW)}$ denotes the space of holomorphic functions smooth up to the boundary. The spectrum of the uniform algebra $\text{A(}\text{}\text{?}\text{gW)}$ is also isomorphic to -Ω. As a corollary we prove an approximation theorem for plurisubharmonic functions in $\text{Ω}$ continuous in -Ω.     

Thermodynamical properties of the relativistic quantum scalar plasma

The thermodynamical properties of the relativistic quantum scalar plasma (i.e. a system of spin one-half baryons interacting through a scalar field) are studied in the Hartree approximation.     

Fonctions holomorphes bornees sur la boule unite deC n

Sans résumé     

Dielectric relaxation,modulus behavior and thermodynamic properties in [N(CH3)3H]2ZnCl4

[N(CH₃)₃H]₂ZnCl₄ has been analyzed by X-ray powder diffraction patterns, differential scanning calorimetry and impedance spectroscopy. The [N(CH₃)₃H]₂ZnCl₄ hybrid compound is obtained by slow evaporation at room temperature and found to crystallize in the orthorhombic system with Pnma space group. Five-phase transitions at low temperature were detected by differential scanning calorimetry measurements. The analysis of Nyquist plots has revealed the contribution of three electrically active regions corresponding to the bulk mechanism, distribution of grain boundaries and electrode processes. The dielectric relaxation is described by a non-Debye model. The study of the dielectric constants ?′, ?″ and loss tangent tan (δ) with frequency exhibits a distribution of relaxation times. The complex modulus plots have confirmed the presence of grains and grain boundaries as well as a non-Debye type of relaxation in the material. Thermodynamic parameters such as the free energy for dipole relaxation ΔF, the enthalpy ΔH and the change in entropy ΔS have been determined with the help of the Eyring theory.     

Probabilistic parameter estimation in a 2-step chemical kinetics model for n-dodecane jet autoignition

This paper demonstrates the development of a simple chemical kinetics model designed for autoignition of n-dodecane in air using Bayesian inference with a model-error representation. The model error, i.e. intrinsic discrepancy from a high-fidelity benchmark model, is represented by allowing additional variability in selected parameters. Subsequently, we quantify predictive uncertainties in the results of autoignition simulations of homogeneous reactors at realistic diesel engine conditions. We demonstrate that these predictive error bars capture model error as well. The uncertainty propagation is performed using non-intrusive spectral projection that can also be used in principle with larger scale computations, such as large eddy simulation. While the present calibration is performed to match a skeletal mechanism, it can be done with equal success using experimental data only (e.g. shock-tube measurements). Since our method captures the error associated with structural model simplifications, we believe that the optimised model could then lead to better qualified predictions of autoignition delay time in high-fidelity large eddy simulations than the existing detailed mechanisms. This methodology provides a way to reduce the cost of reaction kinetics in simulations systematically, while quantifying the accuracy of predictions of important target quantities.     

Complexation of Pu(IV) with the natural siderophore desferrioxamine B and the redox properties of Pu(IV)(siderophore) complexes

The bioavailability and mobility of Pu species can be profoundly affected by siderophores and other oxygen-rich organic ligands. Pu(IV)(siderophore) complexes are generally soluble and may constitute with other soluble organo-Pu(IV) complexes the main fraction of soluble Pu(IV) in the environment. In order to understand the impact of siderophores on the behavior of Pu species, it is important to characterize the formation and redox behavior of Pu(siderophore) complexes. In this work, desferrioxamine B (DFO-B) was investigated for its capacity to bind Pu(IV) as a model siderophore and the properties of the complexes formed were characterized by optical spectroscopy measurements. In a 1:1 Pu(IV)/DFO-B ratio, the complexes Pu(IV)(H2DFO-B)4+, Pu(IV)(H1DFO-B)3+, Pu(IV)(DFO-B)2+, and Pu(IV)(DFO-B)(OH)+ form with corresponding thermodynamic stability constants log beta1,1,2 = 35.48, log beta1,1,1 = 34.87, log beta1,1,0 = 33.98, and log beta1,1,-1 = 27.33, respectively. In the presence of excess DFO-B, the complex Pu(IV)H2(DFO-B)22+ forms with the formation constant log beta2,1,2 = 62.30. The redox potential of the complex Pu(IV)H2(DFO-B)22+ was determined by cyclic voltammetry to be E1/2 = -0.509 V, and the redox potential of the complex Pu(IV)(DFO-B)2+ was estimated to be E1/2 = -0.269 V. The redox properties of Pu(IV)(DFO-B)2+ complexes indicate that Pu(III)(siderophore) complexes are more than 20 orders of magnitude less stable than their Pu(IV) analogues. This indicates that under reducing conditions, stable Pu(siderophore) complexes are unlikely to persist.