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La discoplastía es un procedimiento mínimamente invasivo para tratar pacientes adultos mayores con enfermedad discal degenerativa avanzada con neumodisco, por lo general en la zona lumbar de la columna y con la finalidad de estabilizar y descomprimir los segmentos comprometidos. El procedimiento reduce el dolor del paciente mediante la inyección de cemento óseo en los neumodiscos degenerados consiguiendo así la separación de las vértebras. Mediante el método de elementos finitos se pretende modelizar y evaluar el caso de un paciente ya sometido a la discoplastía debido a su enfermedad discal avanzada, analizar cambios biomecánicos y parámetros como: ángulo resultante del cuerpo vertebral, volumen del foramen de conjunción, volumen de cemento inyectado, entre otros. Los modelos se construyen a partir de imágenes de tomografía computada y se realizan estudios paramétricos de los dominios que los componen: cuerpo vertebral, anillo del disco, núcleo pulposo, y cemento (PMMA)

Estudiamos el comportamiento de agua, metanol y mezclas agua-metanol en un sistema de dos reservorios unidos por un tubo de grafeno mediante simulaciones de dinámica molecular. La imposición de un campo de fuerza sobre una parte del fluido produce una diferencia de presión entre los reservorios e induce un flujo de fluido a través del tubo. Esperamos encontrar modificaciones en el flujo neto según cómo varíe la fracción molar de la mezcla.

Crystallographic data comes from a space-time average over all the unit cells within the crystal, so dynamic phenomena do not contribute significantly to the diffraction data. Many efforts have been made to reconstitute the movement of the macromolecules and explore the microstates that the confined proteins can adopt in the crystalline network. We explored different strategies to simulate a heart fatty acid binding protein (H-FABP) crystal by means of Molecular Dynamics (MD) simulations. We evaluate the effect of introducing restraints according to experimental isotropic B-factors and we analyzed the H-FABP motions in the crystal using Principal Component Analysis (PCA), isotropic and anisotropic B-factors. We compared the behavior of the protein simulated in the crystal confinement versus in solution, and we observed the effect of that confinement in the mobility of the protein residues. Restraining one-third of Cα atoms based on experimental B-factors produce lower B-factors than simulations without restraints, showing that the position restraint of the atoms with the lowest experimental B-factor is a good strategy to maintain the geometry of the crystal with an obvious decrease in the degrees of motion of the protein. PCA shows that, as position restraint reduces the conformational space explored by the system, the motion of the crystal is better recovered, for an essential subspace of the same size, in the simulations without restraints. Restraining only one Cα seems to be a good balance between giving flexibility to the system and preserving its structure. Fil: Espinosa Silva, Yanis Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentina. Universidad Industrial Santander; Colombia Fil: Alvarez, Hugo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentina. Universidad Nacional Arturo Jauretche; Argentina Fil: Howard, Eduardo Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentina. Universidad Tecnológica Nacional; Argentina Fil: Carlevaro, Carlos Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentina. Universidad Tecnológica Nacional; Argentina

Experiments and simulations of an intruder dragged by a spring through a two-dimensional annulus of granular material exhibit robust force fluctuations. At low packing fractions (ϕϕ_{0}), the intruder clears an open channel. Above ϕ_{0}, stick-slip dynamics develop, with an average energy release that is independent of the particle-particle and particle-base friction coefficients but does depend on the width W of the annulus and the diameter D of the intruder. A simple model predicts the dependence of ϕ_{0} on W and D, allowing for a data collapse for the average energy release as a function of ϕ/ϕ_{0}. These results pose challenges for theories of mechanical failure in amorphous materials.

The flow of grains through narrow apertures posses an extraordinary challenge: clogging. Strategies to alleviate the effect of clogging, such as the use of external vibration, are always part of the design of machinery for the handling of bulk materials. It has recently been shown that one way to reduce clogging is to use a small fraction of small particles as an additive. Besides, several works reported that self-repelling magnetic grains can flow through narrow apertures with little clogging, which suggest these are excellent candidates as "lubricating" additives for other granular materials. In this work, we study the effect of adding self-repelling magnetic particles to a sample of grains in two-dimensions. We find that, in contrast with intuition, the added magnetic grains not necessarily aid the flow of the original species.

The molecular structure of membrane lipids is formed by mono- or polyunsaturations on their aliphatic tails that make them susceptible to oxidation, facilitating the incorporation of hydroperoxide (R-OOH) functional groups. Such groups promote changes in both composition and complexity of the membrane significantly modifying its physicochemical properties. Human Langerhans islets amyloid polypeptide (hIAPP) is the main component of amyloid deposits found in the pancreas of patients with type-2 diabetes (T2D). hIAPP in the presence of membranes with oxidized lipid species accelerates the formation of amyloid fibrils or the formation of intermediate oligomeric structures. However, the molecular bases at the initial stage of the anchoring and stabilization of the hIAPP in a hydroperoxidized membrane are not yet well understood. To shed some light on this matter, in this contribution, three bilayer models were modeled: neutral (POPC), anionic (POPS), and oxidized (POPC

We analyze the flow and clogging of circular grains passing through a small aperture under vibration in two dimensions. Via discrete element method simulations, we show that when grains smaller than the original ones are introduced in the system as an additive, the net flow of the original species can be significantly increased. Moreover, there is an optimal radius of the additive particles that maximizes the effect. This finding may constitute the basis for technological applications not only concerning the flow of granular materials but also regarding active matter, including pedestrian evacuation.

The interactions between particles in particulate systems are organized in `force networks', mesoscale features that bridge between the particle scale and the scale of the system as a whole. While such networks are known to be crucial in determining the system wide response, extracting their properties, particularly from experimental systems, is difficult due to the need to measure the interparticle forces. In this work, we show by analysis of the data extracted from simulations that such detailed information about interparticle forces may not be necessary, as long as the focus is on extracting the most dominant features of these networks. The main finding is that a reasonable understanding of the time evolution of force networks can be obtained from incomplete information such as total force on the particles. To compare the evolution of the networks based on the completely known particle interactions and the networks based on incomplete information (total force each grain) we use tools of algebraic topology. In particular we will compare simple measures defined on persistence diagrams that provide useful summaries of the force network features.

A robust, simple and fast procedure for the calculation of uncertainties in static relative permittivity (es) computed via molecular dynamics (MD) is proposed. It arises as a direct application of well founded statistical methods for auto-correlated variables. Also, in order to deal with the lack of experimental data on es and relaxation times at different temperatures, a method for their prediction is suggested. This method requires one experimental value and at least two MD simulations. In the case of relaxation times, a theoretical justification is provided.

We present numerical simulations, based on a CFD–DEM approach, of the transport and settlement of proppant in a planar vertical cell that mimics a hydraulic fracture. These simulations, with resolution at the particle level, allow for a clean measurement of the dune placement and proppant degree of mixing. The effect of the position of the injection points is considered by three different injection heights in the vertical cell. Different proppant injection strategies were also considered by using two different proppant types that can be injected in different orders or simultaneously as a mixture. We evaluate the position and shape of the settled dune. We measure the degree of mixing of the two proppant types by using the concept of mixing entropy. We have found that an injection point placed close to the bottom of the cell leads to a dune close to the injection points, and that an injection point at the middle or at the top of the cell leads to a rather flat dune. Injecting different proppant types in different orders yields distinctive proppant distributions. This helps in evaluating the benefits of positioning perforation clusters close to geological boundaries that favor fracture growth in the upward or downward direction as well as selecting the order of proppant mesh injection. All the simulations correspond to the early stage, before the “traction carpet” effect comes into play Fil: Baldini, Mauro. Universidad Tecnológica Nacional; Argentina Fil: Carlevaro, Carlos Manuel. YPF - Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentina Fil: Pugnaloni, Luis Ariel. Universidad Tecnológica Nacional; Argentina Fil: Sánchez, Martín. Universidad Tecnológica Nacional; Argentina

In this article, dedicated to the memory of Lesser Blum, we develop a theory for the physical clusters which were introduced some time ago in our group (J. Chem Phys. 116, 1097–1108, 2002). The physical cluster definition establishes that a system particle belongs to the cluster if it is (nonspecifically) bonded to other particles of the cluster along a finite time period τ (the residence time). Our theory has as main ingredients the Stillinger criterion of instantaneous connectivity, that involves a connectivity distance d, the generalized time-dependent pair distribution function of Oppenheim and Bloom that acts as a classical propagator and also the cluster pair correlation function for a weaker version of the physical clusters that requires connectivity just at the extremes of the time period no matter what happens in between. With these tools we express the time dependent pair connectedness function for the physical clusters in the strong sense as a path integral. The path integral is solved by means of a perturbation expansion where the nonperturbed connectedness function coincides with the generalized pair distribution function of Oppenheim and Bloom. We apply the theory to Lennard-Jones fluids at low densities and perform molecular dynamics simulations to check the goodness of diverse functions that appear in the theory. Fil: Vericat, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentina Fil: Carlevaro, Carlos Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; Argentina Fil: Stoico, César Omar. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina Fil: Renzi, Danilo Germán. Universidad Nacional de Rosario. Facultad de Ciencias Veterinarias; Argentina

We discuss the results of simulations of an intruder pulled through a two-dimensional granular system by a spring, using a model designed to lend insight into the experimental findings described by Kozlowski et al. [Phys. Rev. E, 100, 032905 (2019)]. In that previous study the presence of basal friction between the grains and the base was observed to change the intruder dynamics from clogging to stick-slip. Here we first show that our simulation results are in excellent agreement with the experimental data for a variety of experimentally accessible friction coefficients governing interactions of particles with each other and with boundaries. Then, we use simulations to explore a broader range of parameter space, focusing on the friction between the particles and the base. We consider a range of both static and dynamic basal friction coefficients, which are difficult to vary smoothly in experiments. The simulations show that dynamic friction strongly affects the stick-slip behaviour when the coefficient is decreased below 0.1, while static friction plays only a marginal role in the intruder dynamics., 19 pages, 10 figures, 2 tables

We report on a series of experiments in which a grain-sized intruder is pushed by a spring through a 2D granular material comprised of photoelastic disks in a Couette geometry. We study the intruder dynamics as a function of packing fraction for two types of supporting substrates: a frictional glass plate and a layer of water for which basal friction forces are negligible. We observe two dynamical regimes: intermittent flow, in which the intruder moves freely most of the time but occasionally gets stuck, and stick-slip dynamics, in which the intruder advances via a sequence of distinct, rapid events. When basal friction is present, we observe a smooth crossover between the two regimes as a function of packing fraction, and we find that reducing the interparticle friction coefficient causes the stick-slip regime to shift to higher packing fractions. When basal friction is eliminated, we observe intermittent flow at all accessible packing fractions. For all cases, we present results for the statistics of stick events, the intruder velocity, and the force exerted on the intruder by the grains. Our results indicate the qualitative importance of basal friction at high packing fractions and suggest a possible connection between intruder dynamics in a static material and clogging dynamics in granular flows., Comment: 10 pages, 11 figures, 1 table. V2: What is now Fig. 5 was added to clarify the raw data measured. References [27] and [37] were updated since they were published only recently

We present simulations using a coupled Computational Fluid Dynamics–Discrete Element Method (CFD–DEM) approach for a slurry of millimeter-sized particles in water which is squeezed between two walls and then made flow out though a narrow aperture. The process is akin to the flowback stage in the near wellbore zone of a hydraulic-stimulated well for hydrocarbon recovery. We consider different wall roughness and investigate its effect on particle production, final distance between walls, spatial particle distribution between the walls, and fluid production rate. We have found that the final distribution of particles changes significantly with small variations in the roughnesses of the walls. This in turn leads to production flow rates that may vary up to 50%. Although the main driver of the production for unconventional wells is the propped fracture network, these results suggest that the roughness of the fracture walls seems to play an important role in the final conductivity and therefore in the ultimate recovery.

In this work, we study bidisperse mixtures of self-propelled magnetic particles of different shapes via discrete element method simulations. We show how these particles self-assemble into clusters and how these clusters depend on the ratio of the mixture, the magnetic interaction, and the shape of the grains. It is found that the mix ratio of the system controls the cluster size. Besides, the intensity of the magnetic dipoles and the shape of the grains in the mixture rule the average number of neighbors in contact and the shape of the clusters. By varying the intensity of the interactions, globular, linear and branched clusters were obtained.

We study the discharge of a two-dimensional silo through small openings via discrete element simulations. We consider the effect of the shape of the grains on the clogging of the flow, focusing on regular polygons and disks. We show that the clogging probability presents a non-linear response as a function of the number of vertexes of the polygons. Also, the clogging probability is strongly dependent on the protocol used to trigger the flow after each clog. We found that the size and shape of the blocking arches display a much larger variability for some polygons, particularly for squares, than for disks. Fil: Goldberg, Ezequiel. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; Argentina Fil: Carlevaro, Carlos Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; Argentina Fil: Pugnaloni, Luis Ariel. Universidad Tecnológica Nacional. Facultad Regional La Plata. Departamento de Ingeniería Mecánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina

We study the dynamical behavior of a single degree of freedom mechanical system with a particle damper. The particle (granular) damping was optimized for the primary system operating condition by using an appropriate gap size for a prismatic enclosure. The particles absorb the kinetic energy of the vibrating structure and convert it into heat through the inelastic collisions and friction. This results in a highly nonlinear mechanical system. Considering linear signal analysis, state space reconstruction, Poincar\'e sections and the determination of maximal Lyapunov exponents, the motion of the granular system inside the enclosure is characterized for a wide frequency range. With the excitation frequency as control parameter, either regular and chaotic motion of the granular bed are found and their influence on the damping is analyzed., Comment: 18 pages, 8 figures. arXiv admin note: text overlap with arXiv:1105.0304

In the companion paper [Pugnaloni, Phys. Rev. E 93, 062902 (2016)10.1103/PhysRevE.93.062902], we use classical measures based on force probability density functions (PDFs), as well as Betti numbers (quantifying the number of components, related to force chains, and loops), to describe the force networks in tapped systems of disks and pentagons. In the present work, we focus on the use of persistence analysis, which allows us to describe these networks in much more detail. This approach allows us not only to describe but also to quantify the differences between the force networks in different realizations of a system, in different parts of the considered domain, or in different systems. We show that persistence analysis clearly distinguishes the systems that are very difficult or impossible to differentiate using other means. One important finding is that the differences in force networks between disks and pentagons are most apparent when loops are considered: the quantities describing properties of the loops may differ significantly even if other measures (properties of components, Betti numbers, force PDFs, or the stress tensor) do not distinguish clearly or at all the investigated systems., Instituto de Física de Líquidos y Sistemas Biológicos

A quaternionic representation of the genetic code, previously reported by the authors (BioSystems 141 (10-19), 2016), is updated in order to incorporate chirality of nucleotide bases and amino acids. The original representation associates with each nucleotide base a prime integer quaternion of norm 7 and involves a function that assigns to each codon, represented by three of these quaternions, another integer quaternion (amino acid type quaternion). The assignation is such that the essentials of the standard genetic code (particularly its degeneration) are preserved. To show the advantages of such a quaternionic representation we have designed an algorithm to go from the primary to the tertiary structure of the protein. The algorithm uses, besides of the type quaternions, a second kind of quaternions with real components that we additionally associate with the amino acids according to their order along the proteins (order quaternions). In this context, we incorporate chirality in our representation by observing that the set of eight integer quaternions of norm 7 can be partitioned into a pair of subsets of cardinality four each with their elements mutually conjugate and by putting them into correspondence one to one with the two sets of enantiomers (D and L) of the four nucleotide bases adenine, cytosine, guanine and uracil, respectively. We then propose two diagrams in order to describe the hypothetical evolution of the genetic codes corresponding to both of the chiral systems of affinities: D-nucleotide bases/L-amino acids and L-nucleotide bases/D-amino acids at reading frames 5'→3' and 3'→5', respectively. Guided by these diagrams we define functions that in each case assign to the triplets of D- (L-) bases a L- (D-) amino acid type integer quaternion. Specifically, the integer quaternion associated with a given D-amino acid is the conjugate of that one corresponding to the enantiomer L. The chiral type quaternions obtained for the amino acids are used, together with a common set of order quaternions, to describe the folding of the two classes, L and D, of homochiral proteins., Instituto de Física de Líquidos y Sistemas Biológicos, Grupo de Aplicaciones Matemáticas y Estadísticas de la Facultad de Ingeniería

The force network of a granular assembly, defined by the contact network and the corresponding contact forces, carries valuable information about the state of the packing. Simple analysis of these networks based on the distribution of force strengths is rather insensitive to the changes in preparation protocols or to the types of particles. In this and the companion paper [Kondic, Phys. Rev. E 93, 062903 (2016)10.1103/PhysRevE.93.062903], we consider two-dimensional simulations of tapped systems built from frictional disks and pentagons, and study the structure of the force networks of granular packings by considering network's topology as force thresholds are varied. We show that the number of clusters and loops observed in the force networks as a function of the force threshold are markedly different for disks and pentagons if the tangential contact forces are considered, whereas they are surprisingly similar for the network defined by the normal forces. In particular, the results indicate that, overall, the force network is more heterogeneous for disks than for pentagons. Such differences in network properties are expected to lead to different macroscale response of the considered systems, despite the fact that averaged measures (such as force probability density function) do not show any obvious differences. Additionally, we show that the states obtained by tapping with different intensities that display similar packing fraction are difficult to distinguish based on simple topological invariants., Instituto de Física de Líquidos y Sistemas Biológicos

A heuristic diagram of the evolution of the standard genetic code is presented. It incorporates, in a way that resembles the energy levels of an atom, the physical notion of broken symmetry and it is consistent with original ideas by Crick on the origin and evolution of the code as well as with the chronological order of appearance of the amino acids along the evolution as inferred from work that mixtures known experimental results with theoretical speculations. Suggested by the diagram we propose a Hamilton quaternions based mathematical representation of the code as it stands now-a-days. The central object in the description is a codon function that assigns to each amino acid an integer quaternion in such a way that the observed code degeneration is preserved. We emphasize the advantages of a quaternionic representation of amino acids taking as an example the folding of proteins. With this aim we propose an algorithm to go from the quaternions sequence to the protein three dimensional structure which can be compared with the corresponding experimental one stored at the Protein Data Bank. In our criterion the mathematical representation of the genetic code in terms of quaternions merits to be taken into account because it describes not only most of the known properties of the genetic code but also opens new perspectives that are mainly derived from the close relationship between quaternions and rotations., Instituto de Física de Líquidos y Sistemas Biológicos, Grupo de Aplicaciones Matemáticas y Estadísticas de la Facultad de Ingeniería

We report two-dimensional simulations of circular and polygonal grains passing through an aperture at the bottom of a silo. The mass flow rate for regular polygons is lower than for disks, as observed by other authors. We show that both the exit velocity of the grains and the packing fraction are lower for polygons, which leads to the reduced flow rate. We point out the importance of the criteria used to define when two objects of different shape are considered to be of the same size. Depending on this criteria, the mass flow rate may vary significantly for some polygons. Moreover, the particle flow rate is non-trivially related to a combination of mass flow rate, particle shape and particle size. For some polygons, the particle flow rate may be lower or higher than that of the corresponding disks depending on the size comparison criteria., Instituto de Física de Líquidos y Sistemas Biológicos

We consider a generalized mean spherical approximation for the pair-connectedness function of a dipolar hard-sphere fluid. Based on its analytical solution, we propose an exponential approach to the continuum percolation of dipolar fluids. The mean cluster size and the critical percolation density so obtained agree well with previously reported Monte Carlo simulations. The Kirkwood factor calculated among connected dipoles, a magnitude that can be taken as a measure of the dipolar ordering inside the cluster, also compares well with the simulation results.

In this comprehensible article we develop, following Fantoni and Rosati formalism, a hypernetted chain approximation for one dimensional systems of fermions. Our scheme differs from previous treatments in the form that the whole set of diagrams is grouped: we do it in terms of non-nodal, non-composite and elementary graphs. This choice makes the deduction of equations more transparent. Equations for the pair distribution functions of one component systems as well as binary mixtures are obtained. We apply they to experimentally realizable quasi-one dimensional systems, the so called quantum wires which we model, within Sommerfeld-Pauli spirit, as a 1D electron gas or as an electron-hole mixture. In order to use our one-dimensional equations we consider pair potentials that depend on the wires width., 41 pages, 14 figures

We simulate, via a discrete element method, the tapping of a narrow column of disks under gravity. For frictionless disks, this system has a simple analytical expression for the density of states in the Edwards volume ensemble. We compare the predictions of the ensemble at constant compactivity against the results for the steady states obtained in the simulations. We show that the steady states cannot be properly described since the microstates sampled are not in correspondence with the predicted distributions, suggesting that the postulates of flat measure and ergodicity are, either or both, invalid for this simple realization of a static granular system. However, we show that certain qualitative features of the volume fluctuations which are difficult to predict from simple arguments are captured by the theory., Instituto de Física de Líquidos y Sistemas Biológicos, Consejo Nacional de Investigaciones Científicas y Técnicas

In the last years, the development of small molecule antagonists of VLA-4 for the treatment of diseases, where cell tra±cking and activation are important, has increased considerably. Among them, the MK-0617 ligand has proven to be a highly potent and orally active 41 antagonist. However, the binding mode of this ligand in the integrin binding site remains unknown. Herein we report a thermodynamic analysis of the interaction between MK-0617 (and one of its isomers) and the VLA-4 protein using molecular docking and the free energy perturbation calculations, based on a comparative model of the 41 receptor. Initial complex coordinates were taken from molecular docking assays and submitted to alchemical transformations. Free energy of binding G values, derived from experimental IC50 values, were taken as a parameter for determining the most likely binding mode. In addition, molecular dynamics simulations of these ligands within the 41 binding site were carried out to elucidate the binding energy pro¯le and identify the most signi¯cant residues. Our results indicate that MK-0617 ¯ts within the binding site in a stretched conformation, pointing the carboxylate group towards the MIDAS ion. We observe that, despite the fact that the main contribution to the energetic binding process is due to the electrostatic ion contribution, the nonpolar contribution is not negligible. Additionally, a network of hydrogen bonds participate in stabilizing the ligand-receptor interaction. Fil: Carlevaro, Carlos Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentina Fil: Martins da Silva, Joao Herminio. Instituto Oswaldo Cruz; Brasil Fil: Savino, Wilson. Instituto Oswaldo Cruz; Brasil Fil: Caffarena, Ernesto Raúl. Instituto Oswaldo Cruz; Brasil