ALBERT

Notes: The analytical solution of the sticky-electrolyte model is obtained in the mean spherical/Percus–Yecvick approximation. This model can be used to represent chemical association in electrolytes. As in the case of the simple mean spherical approximation (MSA), the general solution is given in terms of a single scaling parameter Γ, which is now also a function of the stickiness parameters. We obtain analytic expressions for the thermodynamic functions ΔA, ΔP, and ΔEex. These expressions give the correct limits when the charge is zero (Barboy–Tenne) and when the sticky parameter vanishes. A particularly simple form of the thermodynamic functions is obtained in which the expressions are identical to those of the MSA, but with a different value of Γ, which now depends on the sticky interactions.

Notes: The statistical mechanics of a polydisperse system of charged particles with sticky interactions is studied in the mean spherical/Percus–Yevick approximation. The excess thermodynamic properties are calculated, taking as a reference system the sticky hard spheres mixture and are given in terms of a single scaling parameter ΓT. When the sticking probability is of the form λij=λiλj, then all the equations are explicitly solvable for arbitrary mixtures of charged systems. We obtain explicit expressions for the thermodynamic properties, structure function, and the Laplace transform of the pair distribution function.

Notes: It is shown that a stochastic layer produced by ripple perturbations near the separatrix in tokamaks, leads to anomalous plasma flow out of the bulk plasma along perturbed field lines, which brings out impurities. This suggests that the stochastic layer may play a cleaning role. There is an opposite process of anomalous impurity diffusion into the plasma. The balance of these two processes defines the impurity concentration in the bulk plasma. © 1995 American Institute of Physics.

Notes: The analytical solution of the mean spherical approximation (MSA) for a fluid of hard spheres and a Yukawa potential is obtained by solving a quartic equation for an inverse length parameter Γ. Simple expressions for the thermodynamics and correlation functions in terms of Γ exist in the literature. In this paper we obtain a simple form of the equation of state via the energy. This is compared with the result of Henderson et al. [D. Henderson, L. Blum, and J. P. Noworyta, J. Chem. Phys. 102, 4973 (1995)]. © 1996 American Institute of Physics.

Notes: The analytical solution of mean spherical approximation of the Ornstein–Zernike equation for a Yukawa fluid with factorizable coefficients is used to obtain a simple form of the equation of state for the mixture. These results are an extension of Ginoza's work. © 1996 American Institute of Physics.

Notes: A comprehensive reinterpretation of the available gravity, magnetic, geothermal, geological and borehole information has been made of the Laguna Salada Basin to establish a 3D model of the basement and sedimentary infill. According to statistical spectral analysis, the residual gravity anomaly is due to sources with a mean regional depth of 2.8 km. The topography of the basement was obtained from a three-dimensional inversion carried out in the wavenumber domain using an iterative scheme. The maximum density contrast of −300 kg/m3 estimated from previous studies and the mean depth of 2.5 km finally constrained this inversion. The resulting model indicated that the sedimentary infill is up to 4.2 km thick at its deepest point. According to the gravity-derived basement topography, the basin presents an asymmetry (i.e. it is of the half-graben type). It is deeper to the east, where it is delimited from the Sierra Cucapah by a step fault. By contrast, the limit with the Sierra de Juarez is a gently sloping fault (i.e. a listric fault). The basement is not even, but it comprises a series of structural highs and lows. N–S to NW–SE and E–W to NE–SW faults delimit these structural units.The magnetic modelling was constrained by (i) the gravity-derived basement topography; (ii) a Curie isotherm assumed to be between 7 km and 10 km; (iii) assuming induced magnetization only; (iv) the available geological and borehole information. The magnetic anomalies were interpreted successfully using the gravity-derived basement/sedimentary interface as the top of the magnetic bodies (i.e. the magnetic modelling supports the gravity basement topography). An elongated N–S to NW–SE trending highly magnetized body running from south to north along the basin is observed to the west of the basin. This magnetic anomaly has no gravity signature. Such a feature can be interpreted as an intrusive body emplaced along a fault running through the Laguna Salada Basin. Treatment of the gravity and magnetic information (and of their horizontal gradients) with satellite image processing techniques highlighted lineaments on the basement gravity topography correlating with mapped faults. Based on all this information, we derived detailed geological models along four selected profiles to simulate numerically the heat and fluid flow in the basin. We used a finite-difference scheme to solve the coupled Darcy and Fourier differential equations. According to our results, we have fluid flow in the sedimentary layers and a redistribution of heat flow from the basin axis toward its rims (Sierra de Juárez and Sierra Cucapah). Our model temperatures agree within an error of 4% with the observed temperature profiles measured at boreholes. Our heat-flow determinations agree within an error of ±15% with extrapolated observations. The numerical and chemical analyses support the hypothesis of fluid circulation between the clay–lutite layer and the fractured granitic basement. Thermal modelling shows low heat-flow values along the Laguna Salada Basin. Deep fluid circulation patterns were observed that redistribute such flow at depth. Two patterns were distinguished. One displays the heat flow increasing from the basin axis towards its borders (temperature increase of 20°C). The second pattern shows an increasing heat flow from south to north of the basin. Such behaviour is confirmed by the temperature measurements in the thermometric boreholes.