1,151 research outputs found
Cluster density functional theory for lattice models based on the theory of Mobius functions
Rosenfeld's fundamental measure theory for lattice models is given a rigorous
formulation in terms of the theory of Mobius functions of partially ordered
sets. The free-energy density functional is expressed as an expansion in a
finite set of lattice clusters. This set is endowed a partial order, so that
the coefficients of the cluster expansion are connected to its Mobius function.
Because of this, it is rigorously proven that a unique such expansion exists
for any lattice model. The low-density analysis of the free-energy functional
motivates a redefinition of the basic clusters (zero-dimensional cavities)
which guarantees a correct zero-density limit of the pair and triplet direct
correlation functions. This new definition extends Rosenfeld's theory to
lattice model with any kind of short-range interaction (repulsive or
attractive, hard or soft, one- or multi-component...). Finally, a proof is
given that these functionals have a consistent dimensional reduction, i.e. the
functional for dimension d' can be obtained from that for dimension d (d'<d) if
the latter is evaluated at a density profile confined to a d'-dimensional
subset.Comment: 21 pages, 2 figures, uses iopart.cls, as well as diagrams.sty
(included
L'Origen de l'arquitectura en pedra i l'urbanisme a la Catalunya Occidental
The consolidation of an agricultural economy based in extensive cereals production influenced the development of the typical communities of the plains of western Catalonia during the second millennium BC and the first centuries of the first and differentiated them from the villages of the coast. This paper analyzes the occupation and exploitation pattems of temtories, settlements and specially the development
of stone architecture in the Bronze and Iron Age periods. We characterise the process that leads from the first open-air sedentary settlements to the agricultural settlements in early and middle Bronze Age period and the appearance of wellbuilt houses and town planning during the late Bronze Age.
We can asses the contribution of the early Urnfield period and link the kind of settlement, the town plan, the architecture and building techniques - which centuries later characterised the Ibero-Ilergeta society - to their origin during the
later Urnfield period: systematic exploitation of lands suitable for agriculture (Urgell, Monegros), the phenomenon of concentration-depopulation and the decrease in number of settlements combined with an increase in size.La consolidación de una economia agrícola, basada en el cultivo cerealístic0 extensivo, resulta clave para entender el desarrollo de las comunidades propias de las llanadas de la
Cataluña Occidental a lo largo del segundo milenio y las centurias iniciales del primer0 y su originalidad respecto al experimentado por las poblaciones costeras. Los patrones de ocupación y explotación del territorio, las formas de 10s asentamientos y, en particular, el desarrollo de la arquitectura en piedra y de 10s primeros planteamientos urbanísticos a lo largo de la Edad del Bronce y de la Primera Edad del
Hierro son analizados desde esta óptica.
El proceso histórico, interpretado en clave de continuidad, revela las relaciones entre 10s primeros asentamientos sedentarios al aire libre, 10s establecimientos agrícolas del Bronce Antiguo-Medio y la aparición de la arquitectura sólida y la planificación de 10s poblados durante el Bronce Reciente. Asimismo, permite valorar la aportación de 10s Campos de Urnas Antiguos, y advertir como el tipo de poblamiento, el urbanismo, las soluciones arquitectónicas y las
técnicas constructivas, que siglos mas tarde caracterizarán a la sociedad íbero-ilergeta, tienen su origen en fenómenos abiertos durante 10s Campos de Urnas Recientes; este es el caso de la explotación sistematica de 10s territorios aptos para la agricultura (Urgell, Monegros), el fenómeno de concentración-desploblamiento, la disminución del número de asentamientos combinada con el aumento de su tamaño
Sistema de registro y tratamiento automático de la información en el yacimiento protohistórico de Els Vilars (Arbeca, Lleida)
Sin resume
Estudio experimental comparativo entre el Ligasure® y la técnica de la guillotina como método de biopsia hepática en perros sanos
Lattice density-functional theory of surface melting: the effect of a square-gradient correction
I use the method of classical density-functional theory in the
weighted-density approximation of Tarazona to investigate the phase diagram and
the interface structure of a two-dimensional lattice-gas model with three
phases -- vapour, liquid, and triangular solid. While a straightforward
mean-field treatment of the interparticle attraction is unable to give a stable
liquid phase, the correct phase diagram is obtained when including a suitably
chosen square-gradient term in the system grand potential. Taken this theory
for granted, I further examine the structure of the solid-vapour interface as
the triple point is approached from low temperature. Surprisingly, a novel
phase (rather than the liquid) is found to grow at the interface, exhibiting an
unusually long modulation along the interface normal. The conventional
surface-melting behaviour is recovered only by artificially restricting the
symmetries being available to the density field.Comment: 16 pages, 6 figure
The NADES glyceline as a potential Green Solvent: A comprehensive study of its thermophysical properties and effect of water inclusion
In this paper, two Natural Deep Eutectic Solvents, glyceline (Gly) and glyceline-water (GlyW), containing choline chloride as acceptor H-bond compound and glycerol as donor H-bond group are studied. For glyceline the mole relation is 1 (choline chloride): 2 (glycerol) and for glyceline-water the mole relation is 1 (choline chloride): 1.99 (glycerol): 1.02 water. The ternary NADES has been synthetized and characterized chemically by NMR techniques for this work. Several thermophysical properties in a wide range of temperature (278.15–338.15)¿K and at atmospheric pressure (0.1¿MPa) have been measured for both compounds: density, , speed of sound, , refractive index, , surface tension,, isobaric molar heat capacity, , kinematic viscosity, , and electric conductivity,. Furthermore, some related properties have been also calculated: isobaric expansibility, , isentropic compressibility, , molar refraction, , entropy and enthalpy of surface formationper unit surface area ( and ), and dynamic viscosity, , and viscous flow and electrical conductivity activation energies. The results have been discussed in terms of the effect of temperature and the inclusion of water. We conclude that the compound containing water into the structure has a higher molar volume and a higher fluidity. The binary NADES (Gly) is a more structured liquid than ternary one (GlyW)
Thermophysical characterization of the deep eutectic solvent choline chloride:ethylene glycol and one of its mixtures with water
The deep eutectic solvent ethaline, containing choline chloride as H-bond acceptor and ethylene glycol as H-bond donor and one of its mixture with water are studied in this work. Ethaline is anhydrous, with a 1:2 mol ratio. Hydrated ethaline, choline chloride:ethylene glycol:water, was studied in a 1:1.98:0.95 mol ratio. Several volumetric, acoustic, optical, thermal, surface, and transport properties were measured and calculated. The working temperature ranges from 278.15 to 338.15 K at pressure = 0.1 MPa. The effects of temperature, water inclusion, and the nature of the donor compound are evaluated. With regard to temperature, the system''s behaviour is as expected: a linear relation for the thermodynamic properties and agreement with the Vogel-Fulcher-Tammann equation for the transport properties. The water molecules hardly modify the ethaline structure. The choline chloride – ethylene glycol interactions are weaker than those for choline chloride - glycerol
Fundamental measure theory for lattice fluids with hard core interactions
We present the extension of Rosenfeld's fundamental measure theory to lattice
models by constructing a density functional for d-dimensional mixtures of
parallel hard hypercubes on a simple hypercubic lattice. The one-dimensional
case is exactly solvable and two cases must be distinguished: all the species
with the same lebgth parity (additive mixture), and arbitrary length parity
(nonadditive mixture). At the best of our knowledge, this is the first time
that the latter case is considered. Based on the one-dimensional exact
functional form, we propose the extension to higher dimensions by generalizing
the zero-dimensional cavities method to lattice models. This assures the
functional to have correct dimensional crossovers to any lower dimension,
including the exact zero-dimensional limit. Some applications of the functional
to particular systems are also shown.Comment: 22 pages, 7 figures, needs IOPP LaTeX styles file
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