Enrique Lomba

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• Dr.
• Professor (Full) at Spanish National Research Council

A simple three-dimensional model of a fluid whose constituent particles interact via a short range attractive and long range repulsive potential is used to model the aggregation into large spherical-like clusters made up of hundreds of particles. The model can be thought of as a straightforward rendition of colloid flocculation into large spherical...

A simple model of fluid whose constituent particles interact via a short range attractive and long range repulsive potential is used to model the aggregation of giant clusters made up of hundreds of particles. The model can be thought of as a simplistic representation membraneless organelles or a straightforward rendition of colloid flocculation in...

Chimeric antigen receptor (CAR) T-cell therapy is a promising immunotherapy for treating cancers. This method consists in modifying the patients’ T-cells to directly target antigen-presenting cancer cells. One of the barriers to the development of this type of therapies, is target antigen heterogeneity. It is thought that intratumour heterogeneity...

We present a multiagent-based model that captures the interactions between different types of cells with their microenvironment, and enables the analysis of the emergent global behavior during tissue regeneration and tumor development. Using this model, we are able to reproduce the temporal dynamics of regular healthy cells and cancer cells, as wel...

Ethanol and other biofuels produced during biomass conversion must be separated from the fermentation broth (mainly water) before being used as a fuel. This can be addressed by adsorption-based separation using porous materials. The key objective of this study is to obtain a molecular understanding of water and alcohol adsorption in pure-silica zeo...

The presence of a maximum in density is one of the well-known anomalies of water. This maximum is located at 4°C at room pressure and it moves to lower temperatures as pressure increases. In this work, we attempt to provide a quantitative explanation of the existence of the temperature of maximum density, TMD, and its dependence on pressure, using...

One of the barriers to the development of effective adoptive cell transfer therapies (ACT), specifically for genetically engineered T-cell receptors (TCRs), and chimeric antigen receptor (CAR) T-cells, is target antigen heterogeneity. It is thought that intratumor heterogeneity is one of the leading determinants of therapeutic resistance and treatm...

The temperature of maximum density, TMD, of aqueous solutions of tert-butanol has been experimentally determined in the pressure range of 0-300 bars and up to 0.025 tert-butanol mole fraction. At atmospheric pressure, this quantity increases for low alcohol mole fractions, reaches a maximum at intermediate concentrations, and then quickly falls. Th...

We present a multiagent-based model that captures the interactions between different types of cells with their microenvironment, and enables the analysis of the emergent global behavior during tissue regeneration and tumor development. Using this model, we are able to reproduce the temporal dynamics of healthy epithelial cells and cancer cells, as...

We use theoretical and Monte Carlo computer simulations to study thermodynamic and structural properties of a binary mixture of nonadditive hard-disks. The nonadditivity parameter is set to assume negative values so as to favour heterocoordination between the two species. The theoretical approaches include the Rescaled Virial Expansion Equation of...

Short-chain alcohols at high dilution are among the very few solutes that enhance the anomalous behavior of water, in particular the value of the temperature of maximum density. This peculiar feature, first discovered experimentally in the early twenties, has remained elusive to a full explanation in terms of atomistic models. In this paper, we fir...

We investigate the concentration fluctuations in a simple model of electrolyte (two charged Lennard-Jones spheres in a solution of an uncharged Lennard-Jones liquid) confined between electrodes formed by parallel graphene layers. Using constant potential molecular dynamics simulations and extensive constant charge simulations the effect of the prox...

We study ionic liquid–solvent mixtures in slit-shaped nanopores wider than a few ion diameters. Using a continuum theory and generic thermodynamic reasoning, we reveal that such systems can undergo a capillary ionization transition. At this transition, the pores spontaneously ionize or deionize upon infinitesimal changes of temperature, slit width,...

The excess enthalpy hE and excess volume vE of the binary systems {methanol, ethanol, 1-propanol, 2-propanol, and tert-butanol + water} over the whole composition range at 298.15 K and the temperature of maximum density, TMD, in the alcohol diluted region were studied by MD simulations at atmospheric pressure. Our model systems were defined using t...

Water is a unique material with a long list of thermodynamic, dynamic and structural anomalies, which are usually attributed to the competition between two characteristic length scales in the intermolecular interaction. It has been argued that a potential liquid-liquid phase transition (LLPT) ending at a liquid-liquid critical point (LLCP) lies at...

Molecular dynamics simulations are reported for a protic (ethylammonium nitrate) and an aprotic (1-ethyl-3-methylimidazolium tetrafluoroborate) ionic liquid nanoconfined inside a faujasite-templated carbon. The structure and dynamics of ionic species inside nanotubes of relevant sizes are studied in order to understand the behavior of the dense ion...

Water is an unique material with a long list of thermodynamic, dynamic and structural anomalies, which are usually attributed to the competition between two characteristic length scales in the intermolecular interaction. It has been argued that a potential liquid-liquid phase transition (LLPT) ending at a liquid-liquid critical point (LLCP) lies at...

The creation of disordered hyperuniform materials with extraordinary optical properties (e.g., large complete photonic band gaps) requires a capacity to synthesize large samples that are effectively hyperuniform down to the nanoscale. Motivated by this challenge, we propose a feasible equilibrium fabrication protocol using binary paramagnetic collo...

Short-chain alcohols at high dilution are among the very few solutes that enhance the anomalous behavior of water, in particular the value of the temperature of maximum density. This peculiar feature, first discovered experimentally in the early sixties, has remained elusive to a full explanation in terms of atomistic models. In this paper, we firs...

In this paper we analyze how radiation effects influence the correlation functions, the excess energy, and in turn the electron correlation energy of the quantized electron gas at temperature T=0. To that aim we resort to a statistical mechanical description of the quantum problem of electron correlations, based on the path integral formalism. In p...

Birds are known for their extremely acute sense of vision. The very peculiar structural distribution of five different types of cones in the retina underlies this exquisite ability to sample light. It was recently found that each cone population as well as their total population display a disordered pattern in which long-wavelength density fluctuat...

The temperature of maximum density (TMD) for aqueous solutions of seven amino acids has been experimentally determined by means of density measurements versus temperature. The selected amino acids have been arginine, cysteine, glutamic acid, glutamine, lysine, methionine, and threonine. The TMD dependence against composition has been obtained from...

The creation of disordered hyperuniform materials with potentially extraordinary optical properties requires a capacity to synthesize large samples that are effectively hyperuniform down to the nanoscale. Motivated by this challenge, we propose a fabrication protocol using binary superparamagnetic colloidal particles confined in a 2D plane. The str...

Birds are known for their extremely acute sense of vision. The very peculiar structural distribution of five different types of cones in the retina underlies this exquisite ability to sample light. It was recently found that each cone population as well as their total population display a disordered pattern in which long wave-length density fluctua...

There is a growing interest in the properties of ionic liquids (ILs) and IL-solvent mixtures at metallic interfaces, particularly due to their applications in energy storage. The main focus so far has been on electrical double layers with ILs far from phase transitions. However, the systems in the vicinity of their phase transformations are known t...

In this paper we analyze how radiation effects influence the correlation functions, the excess energy, and in turn the electron correlation energy of the quantized electron gas at temperature $T=0$. To that aim we resort to a statistical mechanical description of the quantum problem of electron correlations, based on the path integral formalism. In...

We study and characterize local density fluctuations of ordered and disordered hyperuniform point distributions on spherical surfaces. In spite of the extensive literature on disordered hyperuniform systems in Euclidean geometries, to date few works have dealt with the problem of hyperuniformity in curved spaces. Indeed, some systems that display d...

There is a growing interest in the properties of ionic liquids (ILs) and IL-solvent mixtures at metallic interfaces, particularly due to their applications in energy storage. The main focus so far has been on electrical double layers with ILs far from phase transitions. However, systems in the vicinity of their phase transformations are known to ex...

The behavior of water, methanol, and water-methanol mixtures confined in narrow slit graphite pores as a function of pore size was investigated by Monte Carlo, hybrid Monte Carlo, and Molecular Dynamics simulations. Interactions were described using TIP4P/2005 for water, OPLS/2016 for methanol, and cross interactions fitted to excess water/methanol...

Electrical double-layers (EDLs) play a key role in energy storage and have been suggested to have applications in energy generation. Recently, there has been an expansion of interest in EDLs, but EDLs with ionic liquid-solvent mixtures (ILSMs) received less attention. Herein, we study the temperature dependence of EDLs with ILSMs, in particular clo...

In this work we present a study on the characterization of ordered and disordered hyperuniform point distributions on spherical surfaces. In spite of the extensive literature on disordered hyperuniform systems in Euclidean geometries, to date few works have dealt with the problem of hyperuniformity in curved spaces. As a matter of fact, some system...

The critical region of the hierarchical reference theory (HRT) is investigated further. This extends an earlier work by us where the critical properties of the HRT were concluded indirectly via another accurate but somewhat different theory, the self-consistent Ornstein-Zernike approximation (SCOZA), and numerical work. In the present work we perfo...

In this paper we present a comparative study of the adsorption behavior of short chain alcohols (pure and in aqueous solution) into silicalite-1 (MFI-type zeolite) and silicalite-2 (MEL-type zeolite). For quite some time, silicalite-1 has been the reference material to address the problem of adsorptive-based separation, mostly for hydrocarbon mixtu...

Disordered hyperuniform materials are new, exotic class of amorphous matter that exhibit crystal-like behavior, in the sense that volume-fraction fluctuations are suppressed at large length scales, and yet they are isotropic and do not display diffraction Bragg peaks. These materials are endowed with novel photonic, phononic, transport and mechanic...

We study the behavior of a two-component plasma made up of non-additive hard disks with a logarithmic Coulomb interaction. Due to the Coulomb repulsion, long-wavelength total density fluctuations are suppressed and the system is globally hyperuniform. Short-range volume effects lead to phase separation or to hetero-coordination for positive or nega...

We study the behavior of a two-component plasma made up of non-additive hard disks with a logarithmic Coulomb interaction. Due to the Coulomb repulsion, long-wavelength total density fluctuations are suppressed and the system is globally hyperuniform. Short-range volume effects lead to phase separation or to hetero-coordination for positive or nega...

The critical region of the hierarchical reference theory (HRT) is investigated further. This extends an earlier work by us where the critical properties of the HRT were concluded indirectly via another accurate but somewhat different theory, the self-consistent Ornstein-Zernike approximation (SCOZA), and numerical work. In the present work we perfo...

Disordered multihyperuniform many-particle systems are exotic amorphous states that allow exquisite color sensing capabilities due to their anomalous suppression of density fluctuations for distinct subsets of particles, as recently evidenced in photoreceptor mosaics in avian retina. Motivated by this biological finding, we present the first statis...

Disordered multihyperuniform many-particle systems are exotic amorphous states that allow exquisite color sensing capabilities due to their anomalous suppression of density fluctuations for distinct subsets of particles, as recently evidenced in photoreceptor mosaics in avian retina. Motivated by this biological finding, we present the first statis...

In this article we continue and extend our recent work on the correlation energy of the quantized electron gas of uniform density at temperature $T=0$. As before we utilize the methods, properties, and results obtained by means of classical statistical mechanics. These were extended to quantized systems via the Feynman path integral formalism. The...

Densities of several aqueous mixtures of 2-pentanol, 3-pentanol, and 2-methyl-2-butanol in the diluted alcohol region were determined in the temperature interval (273.65-282.15) K at atmospheric pressure using the Anton Paar DSA48 vibrating tube densimeter. The variation of the temperature of maximum density with respect to that in pure water , its...

Using computer simulations, we study the phase diagram of a two-dimensional system of disk particles with three patches distributed symmetrically along the particle equator. The geometry of the particles is compatible with a honey-comb lattice at moderately low temperature and pressure, whereas it is expected that the system forms a close-packed tr...

NRMC is a parallel code for performing N-Reverse Monte Carlo modeling of fluids in confined media [V. Sánchez-Gil, E.G. Noya, E. Lomba, J. Chem. Phys. 140 (2014) 024504]. This method is an extension of the usual Reverse Monte Carlo method to obtain structural models of confined fluids compatible with experimental diffraction patterns, specifically...

We perform an extensive computational study of binary mixtures of water and short-chain alcohols resorting to two-scale potential models to account for the singularities of hydrogen bonded liquids. Water molecules are represented by a well studied core softened potential which is known to qualitatively account for a large number of water's characte...

We perform an extensive computational study of binary mixtures of water and short-chain alcohols resorting to two-scale potential models to account for the singularities of hydrogen bonded liquids. Water molecules are represented by a well studied core softened potential which is known to qualitatively account for a large number of water's characte...

In this work we continue and extend our recent work on the correlation energy of the quantized electron gas of uniform density at temperature $T=0$. As before we utilize the methods, properties, and results obtained by means of classical statistical mechanics. These were extended to quantized systems via the Feynman path integral formalism. The lat...

In this work we study the correlation energy of the quantized electron gas of uniform density at temperature $T=0$. To do so we utilize methods from classical statistical mechanics. The basis for this is the Feynman path integral for the partition function of quantized systems. With this representation the quantum mechanical problem can be interpre...

In this work we have assessed the ability of a recently proposed three dimensional integral equation approach to describe the explicit spatial distribution of molecular hydrogen confined in a crystal formed by short-capped nanotubes of C50H10. To that aim we have resorted to extensive molecular simulation calculations whose results have been compar...

On Monday, June 13th, there will be an academic session at the IQFR-CSIC dedicated to the memory of our colleague, friend and member of the ResearchGate community N.G. Almarza, deceased on May 5th, 2016.

In this work, the adsorption of toluene on pure-silica MEL zeolite is investigated using a variety of experimental and simulation methods. First, we measured the volumetric and calorimetric isotherms at 301 K and at 315 K. The volumetric adsorption isotherm presents a substep at a loading of roughly 4 molecules per unit cell that shifts to higher p...

In this work, we present a study of representative excess thermodynamic properties of aqueous mixtures of methanol over the complete concentration range, based on extensive computer simulation calculations. In addition to test various existing united atom model potentials, we have developed a new force-field which accurately reproduces the excess t...

In this work we study the correlation energy of the quantized electron gas of uniform density at temperature $T=0$. To do so we utilize methods from classical statistical mechanics. The basis for this is the Feynman path integral for the partition function of quantized systems. With this representation the quantum mechanical problem can be interpre...

In this work, we investigate the structure of argon adsorbed on pure-silica MEL at liquid nitrogen temperature. Our goal is to provide a microscopic interpretation for the appearance of a sub-step in the adsorption isotherm at intermediate loadings before saturation. For that purpose, we first perform time-of-flight neutron diffraction experiments...

The adsorption isotherm of argon on the zeolite MFI at liquid nitrogen temperature exhibits a sub-step at high loading before saturation that, in spite of much theoretical and experimental effort, is still lacking a definitive microscopic interpretation. In this work, we try to get insight into this peculiar behaviour by investigating the adsorptio...

In this work we explore the ability of an inhomogeneous integral equation approach to provide a full three dimensional description of simple fluids under conditions of confinement in porous media. Explicitly we will consider the case of argon adsorbed into silicalite-1, silicalite-2 and an all-silica analogue of faujasite, with a porous structure c...

Molecular dynamics simulations and integral equation calculations of a simple equimolar mixture of diatomic molecules and monomers interacting via attractive and repulsive short-range potentials show the existence of pattern formation (microheterogeneity), mostly due to depletion forces away from the demixing region. Effective site-site potentials...

The behavior of a fluid with competing interaction ranges adsorbed in a controlled pore size disordered matrix is studied by means of grand canonical Monte Carlo simulations in order to analyze the effects of confinement. The disordered matrix model is constructed from a two-dimensional non-additive hard-sphere fluid (which shows close to its demix...

Using Monte Carlo simulation, we study the influence of geometric confinement on demixing for a series of symmetric non-additive hard spheres mixtures confined in slit pores. We consider both a wide range of positive non-additivities and a series of pore widths, ranging from the pure two dimensional limit to a large pore width where results are clo...

Using Monte Carlo simulation, we study the influence of geometric confinement on demixing for a series of symmetric non-additive hard spheres mixtures confined in slit pores. We consider both a wide range of positive non-additivities and a series of pore widths, ranging from the pure two dimensional limit to a large pore width where results are clo...

We study the fluid inclusion of both Lennard-Jones particles and particles with competing interaction ranges --short range attractive and long range repulsive (SALR)-- in a disordered porous medium constructed as a controlled pore glass in two dimensions. With the aid of a full two-dimensional Ornstein-Zernike approach, complemented by a Replica Or...

In this contribution we review a series of simple one dimensional lattice models that with an appropriate choice of parameters can account for various anomalous features of the behaviour of complex systems such as water. In particular, we will focus on the presence of $p-T$ fluid-solid coexistence lines with negative slope (i.e. solids that melt up...

In this paper we investigate the adsorption of various probe molecules in order to characterize the porous structure of a series of pillared interlayered clays (PILC). To that aim, volumetric and microcalorimetric adsorption experiments were performed on various Zr PILC samples using nitrogen, toluene, and mesitylene as probe molecules. For one of...

The crystal structure of the Sup35 prion segment, GNNQQNY, revealed precise side chain packing and an extensive H-bond network. However, the conformers and stabilizing interactions involved at nascent amyloid formation are still unclear. Here, long molecular dynamics simulations and quantum mechanical calculations have been utilized to study the co...

An extension of the well established Reverse Monte Carlo (RMC) method for modeling systems under close confinement has been developed. The method overcomes limitations induced by close confinement in systems such as fluids adsorbed in microporous materials. As a test of the method, we investigate a model system of (36)Ar adsorbed into two zeolites...

The hierarchical reference theory (HRT) is generalized to spins of dimensionality $D$. Then its properties are investigated by both analytical and numerical evaluations for supercritical temperatures. The HRT is closely related to the self-consistent Ornstein-Zernike approximation (SCOZA) that was developed earlier for arbitrary $D$. Like the $D=1$...

This f90 code solves the HNC integral equation for the primitive model of electrolytes

The phase behaviour of the Lebwohl-Lasher lattice gas model (one of the simplest representations of a nematogenic fluid) confined in a slab is investigated by means of extensive Monte Carlo simulations. The model is known to yield a first order gas-liquid transition in both the 2D and 3D limits, that is coupled with an orientational order-disorder...

The stability of complexes of a recently synthetized (Scott et al. J. Am. Chem. Soc. 2011, 134, 107) opened nanocontainer C50H10 with several guest molecules, H-2, N-2, CO, HCN, H2O, CO2, CS2, H2S, C2H2, NH3, CH4, CH3CN, CH3OH, CH3CCH, 2-butyne, methyl halides, and with noble gas atoms, has been examined by means of symmetry adapted perturbation th...

The critical region of the hierarchical reference theory (HRT) is investigated both by analytical and numerical methods. This is closely related to a recent work by one of us where the HRT was unified with another accurate theory, the self-consistent Ornstein–Zernike theory (SCOZA). It was found that somehow the properties of HRT alone would be clo...

The effects of packing of n-hexane molecules in the channels of a ZSM-11 zeolite are studied by means of adsorption microcalorimetric and volumetric experiments and molecular simulation. We find that the packing density within the zeolite channels is significantly higher than the bulk liquid density. This effect, somewhat characteristic of the n-he...

The phase behavior of confined nematogens is studied using the Lebwohl-Lasher model. For three dimensional systems the model is known to exhibit a discontinuous nematic-isotropic phase transition, whereas the corresponding two dimensional systems apparently show a continuous Berezinskii-Kosterlitz-Thouless like transition. In this paper we study th...

The preparation, characterization and comparison of nanostructured carbons derived by direct chlorination of Cr3C2 and Cr(C5H7O2)3 are reported in this work. Cr3C2 precursor was treated at 400 and 900°C with a reaction time of 1h. The nanostructure of the products has been characterized in some detail by means of transmission electron microscopy an...

A pillared interlayered clay is represented by a two-dimensional quenched charged disordered medium, in which the pillar configuration is produced by the quench of a two-dimensional electrolyte and the subsequent removal of the anions (that act as a template). The cation charge is counterbalanced by a neutralizing background that is an ideal repres...

We analyse the phase behaviour of a simple one-dimensional lattice model with two repulsive ranges (a hard core repulsion that covers two sites and a next-to-nearest neighbour repulsive interaction), a long-ranged staggered mean field, and an additional mean field attraction. The model is investigated in terms of its analytic solution. By a suitabl...

The microporous structure of pillared interlayered clays is determined by their interlayer separation and the distribution of the pillars that separate their layers. The pillars provide stability to these quasi-two-dimensional high surface area materials. In this work we present a topological analysis of available and accessible volumes within vari...

Using Monte Carlo simulation and fundamental measure theory we study the phase diagram of a two-dimensional lattice gas model with a nearest neighbor hard core exclusion and a next-to-nearest neighbor finite repulsive interaction. The model presents two competing ranges of interaction and, in common with many experimental systems, exhibits a low de...

The Maier-Saupe hard-sphere fluid is one of the simplest models that accounts for the isotropic-nematic transition characteristic of liquid crystal phases. At low temperatures the model is known to present a gas-liquid-like transition with a large difference between the densities of the coexistence phases, whereas at higher temperature the transiti...

Using Monte Carlo Simulation and fundamental measure theory we study the phase diagram of a two-dimensional lattice gas model with a nearest neighbor hard core exclusion and a next-to-nearest neighbors finite repulsive interaction. The model presents two competing ranges of interaction and, in common with many experimental systems, exhibits a low d...

In this paper we present an alternative formulation of the well-known integral equation approximations designed to keep a consistent approach to the determination of thermodynamic properties in the case of density-dependent interactions. Obviously, residual inconsistencies inherent to the approximate character of the closure relations of the Ornste...

The properties of a simple one-dimensional lattice model with two repulsive ranges (a hard core repulsion that covers two sites and a next-to-nearest neighbour repulsive interaction) and a long-ranged staggered mean field, are studied in terms of its analytic solution. A related three-dimensional lattice model is analysed using computer simulation....

The products of the direct chlorination of B4C at different temperatures (700, 900 and 1050 °C, with a reaction time of 90 minutes) have been characterised mainly by means of electron microscopy and associated techniques, such as X-ray energy dispersive spectroscopy and electron energy-loss spectroscopy. The micro and nanostructure of the prepared...

We study the demixing transition of mixtures of equal size hard spheres and dipolar hard spheres using computer simulation and integral equation theories. Calculations are carried out at constant pressure, and it is found that there is a strong correlation between the total density and the composition. The critical temperature and the critical tota...

The properties of a simple one-dimensional lattice model with two repulsive ranges are studied in terms of its analytic solution. Its phase behavior is characterized by the presence of a disorder-order-disorder transition (or a fluid-solid-fluid transition in lattice gas language). A similar situation was discussed by Hemmer and Stell [Phys. Rev. L...

With the concourse of a variety of experimental techniques (neutron diffraction, x-ray photoelectron spectroscopy, 13C nuclear magnetic resonance, electron microscopy, and Raman spectroscopy) and a combination of reverse Monte Carlo, molecular dynamics, and Monte Carlo simulations, we propose a model for the microscopic structure of a sample of car...

The preparation of nanocarbons and the study of their promising applications have attracted considerable attention in the last years [1,2]. Carbide-derived carbons (CDC) are a well-known group of nanostructured carbon materials, prepared by direct chlorination of the metal carbides according to the following reaction: MCx(s) + y/2 Cl2(g) → x C(s) +...

In this work we investigate the phase behavior of a family of continuous bidimensional n -vector models (with n=2, 3, and 4) using Monte Carlo simulation. In all cases we detect the presence of a defect mediated order-disorder transition of the Berezinskii-Kosterlitz-Thouless type with critical temperatures that decrease with the spin dimensionalit...

The classical XY model describes particles in three-dimensional space that carry magnetic moments or spins whose motion is restricted to rotations in a plane. Introduction of an external magnetic field lying in the same plane then generates a system that is anisotropic in the azimuthal angle phi . We use numerical simulations and integral equation...