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Structural features of the glass family xLi2O- yMgO (4.8 Bi2O3 47.6 P2O5) obtained by melt quenching technique were studied taking into account the density, FTIR and UV–vis spectra and also the electrical response observed by impedance spectroscopy. In this work it becomes clarified how the alkaline earth oxides stabilize the glassy matrix and also, the fundamental importance of determining the optimal proportion in order to obtain a flabby easily polarizable matrix to enhance the electrical behavior due to a boosted cation mobility. It is evidenced that when the glass composition becomes complex it is needed to take into account a larger number of structural parameters to understand, to predict or to design the resulting physical properties.

Physics Nobel Prize winner P.W. Anderson famously wrote in 1995: “The deepest and most interesting unsolved problem in solid state theory is probably the theory of the nature of the glass and the glass transition”. Despite much effort in the intervening years, the problem is still unsolved. We contribute a novel mathematical approach to this problem. The main new ingredient is finite dimension, a recently introduced “fractal” dimension defined only for finite sets. Our methods sharply distinguish the glass transition temperature and give hints as to the structural changes that occur in the transition.

In this work a modified glassy micro-particles glucose sensor was developed applying a new and effective procedure to anchor glucose oxidase on glassy micro particles using urea medium. The resulting sensor, in the presence of glucose, generates a color development in 60 seconds working at room temperature. The intensity of the resulting color shows a straightforward relationship with the glucose concentration in the samples tested. The resulting biosensor was tested to demonstrate its sensibility on dissolutions of glucose and honey. Fil: Zoratti, Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Centurión, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

The interactions between the [BMIM][PF6] -ionic liquid- and a phosphate glassy surface is studied through calorimetric, structural and impedance spectroscopy methods. A soft solid conductor material is obtained mixing the ionic glass powder with the ionic liquid in a low proportion (2% and 4%). At microscopic level, the interactions of this ionic liquid with the glassy particle surfaces reveal the formation of new bridging oxygens. Therefore, the material electrical conductivity increases in more than four orders of magnitude. This finding uncovers the essential elements to be considered before incorporating an additional salt to develop a solid electrolyte.

The reinforcement of the ionic conductivity in a lithium-vanadium-molybdenum tellurite glass is possible by modified with zinc oxide {0.7 [x ZnO (1 − x) Li2O] 0.3 [0.5 V2O5. 0.5 MoO3]. 2TeO2}. Structural features induced by zinc cation on the glassy matrix have a positive effect on the electrical behavior of the modified glass. The electrical response of the Zn/Li tellurite glass studied in the present work gives evidence that its ionic conductivity is improved due to the incorporation of small quantities of ZnO suggesting a potential solid ionic electrolyte useful in solid electrochemical devices. Fil: Di Pratula, Pablo Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Terny, Cintia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Sola, Mariela Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

New materials based on V2O5, TeO2 and a combination of graphite, graphene oxide and multiwalled carbon nanotubes were developed and tested as potential electrochemical sensors. A mixture design with three components in combination with multi-response assays based on the desirability function was used as multivariate optimization for the system composition. The optimal sensor contains graphene oxide and multiwalled carbon in approximately equal amounts. The new sensors characterizations were performed with X-ray diffraction, differential scanning calorimetry, impedance spectroscopy and cyclic voltammetry. The main advantage of this electrodes are does not requires surface activation and exhibited a potential electroanalytical performance with different targeted analytes such as ascorbic acid, aspartame and lead. Fil: Pierini, Gastón Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Pratula, Pablo Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Ochoa, Ana Laura. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina Fil: Centurión, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

Glasses formed by different oxides are of uppermost importance because they aredeveloped for many applications in electronics, optics, biology, etc. Oxide glasses are built by a three-dimensional network of corner connected oxygen polyhedral that can be modified by the inclusion of other oxides such as transition metal oxides. In this work, the polaron conductivity due to the presence of transition metal oxides in tellurite glasses is analyzed in systems containing alkaline (AO) and alkaline earth oxides (AEO). It is explained how the presence of metal cations (AO or AEO) affects the displacement of the polaron through the network due to the ion-polaron interaction. Fil: Hernandez Garcia, Luis Ancizar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Molina, Magalí Cielo. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Zoratti, Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Cardillo, Evangelina Cinthia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Terny, Cintia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Sola, Mariela Edith. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

When a liquid is quenched, a disordered solid is obtained. That solid can be a glass or a polycrystalline material. If a glass is obtained, understanding the variation of time dependence of its physical properties-such as the glasses? structural relaxation-is crucial. The glass transition process is commonly associated with a frozen liquid structure trapped during the quenching. In thiswork, the aging phenomenon is correlated to the modifier cation content in a studied ionic conductor phosphate glass. This is a critical knowledge needed for cost-effective materials, because of the potential changes in their material electrical behavior. Structural and electrical evidence of the damage suffered by a slight overheating of a highly concentrated ionic glass is presented. Fil: di Prátula, P. E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Molina, M. C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: López, O.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina Fil: Villar, Marcelo Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

Silver iodide (AgI) is one of the most extensively studied superionic conductors. In this work, we have applied the standard Buckingham pair potential and standard charge. For the first time the microscopic dynamic events that allow the achievement of the superionic transition are revealed. A collaborative effect among cations and anions that makes possible the hopping mechanism within the appropriate timescale is revealed. Fil: Tulandy, Eider Iván Vivas. Universidad Politécnica de Cartagena; España Fil: García Muriel, Alvaro. Universidad de Cartagena; Colombia Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

New mixed composite conductors of compositions: Li3V2−x [Cu]x (PO4)3/C and Li3V2−x [Nb]x(PO4)3/C (x = 0.1; 0.2 and 0.3) have been synthesized by the sol-gel method using Citric and Oxalic acids as a primary carbon source and Carbon Black or Carbon Nano-Fibers as secondary carbon sources. The combination of these carbon forms with the Nb doped-polyanion material boosts their electrical behavior up to 10−3 S.m−1 that is two orders of magnitude higher than the Li3V2(PO4)3/C at a room temperature. SEM, TEM and Micro-Raman Spectroscopy evidence that Carbon Nano-Fiber blend is better conductor than Carbon Black blend, which is also revealed by complex conductivity spectra. The conductivity behavior of Nb-doped ceramic is better than the Cudoped one. The obtained niobium composites have a much more stable structure compared to the copper ones because the niobium atoms fit well in the vanadium position, whereas copper atoms are expelled from the structured. Fil: Terny, Cintia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Vega Castillo, Jesus Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina Fil: de la Rubia, María Ángeles. Centro de Materiales y Dispositivos Avanzados para TIC. Grupo de Propiedades Ópticas, Eléctricas y Magnéticas de Materiales y sus Aplicaciones.; España Fil: de Frutos, José. Centro de Materiales y Dispositivos Avanzados para TIC. Grupo de Propiedades Ópticas, Eléctricas y Magnéticas de Materiales y sus Aplicaciones.; España Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

NiFe2O4 spinel – phosphate (Bi-Ba-Li) glass composite was synthesized by solid-state reaction. New crystalline magnetic phases was developed inside the glassy matrix through a controlled heat treatment. New NF-LBPB4 magnetic nanocomposite material was study. Complex impedance analysis has shown that mobile ions inside the matrix induce the development of complementary crystalline phases resulting in a composite material with excellent magnetic response. An innovative homemade device was designed to test the nanocomposite magnetic response. Fil: Di Pratula, Pablo Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Pistonesi, Carlos Alberto. Universidad Tecnológica Nacional; Argentina Fil: Anton, Marcelo Alejandro. Universidad Tecnológica Nacional; Argentina Fil: Di Prátula, Horacio Raúl. Universidad Tecnológica Nacional; Argentina Fil: Guillermo, Eduardo Daniel. Universidad Tecnológica Nacional; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

[EN] In this work, nitrogen-doped hierarchical porous carbon (NPC) was obtained from an effective and facile synthesis route based on metal-organic framework (MOF)-drive approach using Zr-metal-organic framework (UiO-66-NH2) as a template. The structural analysis of synthesized NPC using different heat treatment was performed through X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and N-2 adsorption-desorption isotherm at 77K characterization. The results achieved indicate that Zr-MOF is an appropriate starting precursor to attain functional carbon materials with remarkable physicochemical properties for potential advanced applications. Thereby, it was evidenced that the NPC synthesis temperature has an influence on resulting structural properties as well as nitrogen functionalities and amount. Thereby, the obtained NPC exhibits a disorder porous structure with high BET surface area (765-867 m(2)/g), pore size from microporous to mesoporous, and 3-4% of N content. Related to nitrogen functionalities, the heteroatom corresponds to quaternary, pyrrolic, and pyridinic bonding, indicating that it was successfully incorporated into the carbon framework., The authors thank Agencia Promotion Nacional de Promocion Cientifica y Tecnologica, Argentina, Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), PICT 2016-0101 Argentina Innovadora, PGI Q24/078 and MAT2017-82288-C2-1-P projects for the financial support.

The electrical behavior of a bismuth-phosphate glass lithium ion conductor is studied in a very wide temperature range, from 39 K to 843 K, encompassing the glassy state, passing through the glass transition temperature, and reaching devitrification. The relationship between the structural changes caused by the thermal treatment and the resulting electrical response is interpreted through the dc conductivity and ac permittivity. An isothermal and a non-isothermal treatment allows to propose a simple analysis of the energy distribution and atoms rearrangement times involved in devitrification, using a Gaussian approximation method considering the fundamental elements in the M. Avrami’s generalized theory.

Glasses of composition 0.8 [xBaO.(1-x)MgO]. 0.2TM.2TeO2 with TM: MoO3, WO3, V2O5 or Nb2O5 (x= mol content) were obtained by the melt quenching technique. Raman Spectroscopy, Density and Differential Scanning Calorimetry were used to infer their microscopic structure and electrical properties were studied using Impedance Spectroscopy. Some singularities in their electrical and structural properties appeared. Deviations from linearity as a function of alkaline-earth oxide modifier content were observed both on the electrical and structural properties. They were analyzed considering the intensity of the electrical field of the mix of alkaline earth cations which induced changes on the glassy matrix and the mixed alkaline-earth effect was considered. The observed relationships between their electrical and structural properties and the mix of alkaline earth cations were different according to the transition metal oxide present. Fil: Terny, S.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: De la Rubia, M.. Universidad Politecnica de Madrid; España Fil: De Frutos Vaquerizo, J.. Universidad Politecnica de Madrid; España Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina

Mixed alkaline-earth effect (MAEE) on the transition metal oxides (TMO)-tellurite glasses [TMO = MoO3, Nb2O5 and WO3] modified with BaO/MgO mix is analyzed to understand how feasible it is to tune structural and optical properties of a tellurite glass. Changes induced by the three transition metal oxides on the tellurite polyhedral produce some modifications on the cut-off wavelength, optical band gap, Urbach's energy, refractive index and permittivity values where the MAEE manifest itself in different ways. The changes in the glass structural properties are dominated by the TMO type while optical and electrical properties depend mostly on the combination between the TMO and the [BaO/(BaO + MgO)] ratio. Glass transition temperature is discussed in terms of some parameters like number of bonds per unit volume, average stretching force constant, molar volume, oxygen packing density values (OPD) and FTIR spectra. In this work we provide evidence that the behavior attributed to the relationship between structure and electrical or optical properties in pure oxide and even binary systems is not reproduced by multi-component glassy systems. A comparison between traditional and new optical methods confirm allowed direct inter-band electronic transitions in the studied glasses evidencing that the a priori parameter election is not always an accurate procedure.

In this work, the electrical behavior and structural features of the system x Cu 2 O ( 1 − x ) (0.5V 2 O 5 ·0.5MoO 3 ) 2TeO 2 compared to x Ag 2 O ( 1 − x ) (0.5V 2 O 5 ·0.5MoO 3 ) 2TeO 2 (which was already studied) are explored. The main goal is to determine whether the electronic configuration of Cu + and Ag + ions is the key to understand the interactions of these ions with vanadium ions in the glassy matrix studied and to establish the nature of the particular electrical conductivity response. It is shown that despite the fact that both ions (Cu + and Ag + ) have similar electronic configurations but different sizes they have similar electrical behaviors contrary to what is commonly accepted ( i.e. silver modified glasses are completely ionic systems, while copper modified glasses are purely electronic –polaronic- semiconductors). It is expected that both behave as mixed electrical conductors, neither pure polaronic nor pure ionic. It has been found that the minimum observed in the isotherm of conductivity can be explained by the structural features of this glassy matrix and not by a change in its mechanism of conduction.

Monolayers of n-eicosanephosphonic acid, EPA, were studied using a Langmuir balance and a Brewster angle microscope at different subphase pH values to change the charge of the polar headgroups (Zav) from 0 to -2. Molecular dynamics simulations (MDS) results for |Zav| = 0, 1, and 2 were compared with the experimental ones. EPA monolayers behave as mixtures of mutually miscible species (C20H41-PO3H2, C20H41-PO3H(-), and C20H41-PO3(2-), depending on the subphase pH). The order and compactness of the monolayers decrease when increasing |Zav|, while go from strongly interconnected by phosphonic-phosphonic hydrogen bonds (|Zav| = 0-0.03) through an equilibrium between the total cohesive energy and the electrostatic repulsion between the charged polar groups (0.03|Zav|1.6) to an entirely ionic monolayer (|Zav| ≈ 2). MDS reveal for |Zav| = 0 that the chains form spiralled nearly rounded structures induced by the hydrogen-bonded network. When |Zav| ≈ 1 fingering domains were identified. When Z ≈ 2, the headgroups are more disordered and distanced, not only in the xy plane but also in the z direction, forming a rough layer and responding to compression with a large plateau in the isotherm. The monolayers collapse behavior is consistent with the structures and domains founds in the different ionization states and their consequent in-plane rigidity: there is a transition from a solid-like response at low pH subphases to a fluid-like response at high pH subphases. The film area in the close-packed state increases relatively slow when the polar headgroups are able to form hydrogen bonds but increases to near twice that this value when |Zav| ≈ 2. Other nanoscopic properties of monolayers were also determined by MDS. The computational results confirm the experimental findings and offer a nanoscopic perspective on the structure and interactions in the phosphonate monolayers.

We summarize recent studies of oxide ion dynamics in ionically conducting defect pyrochlores of general formulae Ln 2 Ti 2 − y Zr y O 7 . Unit cell volume, structural disorder, and ion–ion interactions, are all relevant in determining ion hopping probability and thus the mobility of oxide ions at high temperatures. At enough low temperatures ion hopping is scarce and oxide ion dynamics are restricted to local displacements within the cage.

According to the fundamental theory, the interaction ofelectromagnetic field with matter is well described by Maxwell’sequations [1]. The thing is, if we disturb the matter applying analternant potential difference through it a resonance phenomenontakes place. If we capture that response as a signal it is possible tointerpret what is happening inside. And, this word inside is probablythe most attractive thing when we are dealing with alive organisms because we want to study them without damaging them. Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

Performing Molecular Dynamic simulations and using the isoconfigurational ensemble method, we studied the effect of the potassium cation replacing the half part of lithium ions in glassy Li2SiO3. This so-constructed glassy system has the main ingredients present in an immediate forthcoming definition of mixed alkali effect (MAE) in glasses. We show the existence of dynamic correlations among the cations of the same species, i.e. Li–Li and K–K, whereas a very weak correlation was observed between a distinct pair of cations. With this novel approach we can put into evidence that the alkali ion diffusion evolves in specific channels for the ions: a Li ion prefers the lithium ion channel and a K ion prefers the potassium ion channel. This result is coincident with previous simulational studies using the bond–valence technique to reverse Monte Carlo and recent experimental findings using quasielastic neutron scattering. Fil: Balbuena, Cristian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Montani, Ruben Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

A low cost composite electrodes employing tellurite oxide, vanadium oxide and micrometric granular graphite (NWE), were designed as an alternative to be used as working electrode in voltammetry techniques. The synthesis of these composite electrodes is carried out easily; in a short time and their surface not require previous preparation. X-ray diffraction, X-ray fluorescence spectrometry and optical microscopy studies were used to determine the morphology and chemical composition of these electrodes. The conductivity characterization was conducted with impedance and electrochemical measurements. The electrochemical properties of NWE were studied using potassium hexacyanoferrate (II) and ascorbic acid system. Fil: Pierini, Gastón Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Presa, Jimena Mailén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Centurión, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Nezio, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

En este trabajo estudiamos la estructura de un material vitreo cuya formula general es: xMgO(1-x)(0.5V2O5.0.5MoO3)2TeO2 (0.x.0.9), mediante medidas de densidad, volumen molar, empaquetamiento denso de oxigeno (OPD), calorimetria diferencial de barrido (DSC) y espectroscopia Raman; el comportamiento electrico se estudio por medio de espectroscopia de impedancia. Encontramos que el cation magnesio induce el crecimiento de zonas levemente cristalizadas dentro del material. Dichas nanocristalizaciones pudieron ser detectadas en mayor medida por microscopia de fuerzas atomicas (AFM) y en menor medida se pudo observar en los patrones de difraccion de Rayos X (DRX). Con respecto a las propiedades electricas, se puede establecer que el cation magnesio no actua como buen conductor ionico en este material.

In this paper, we analyze using differential scanning calorimetry (DSC) how a disordered structure, obtained by the quenching of oxides melted into glass, is related to the nature of the modi- fier cation. We estimated the enthalpy relaxation in based tellurite oxide glasses of formula xM2O (1−x)(0.5 V2 O5 ·0.5MoO3 ) 2TeO2 when they are modified with univalent metal oxides as Na+ , Li+ and Ag+. As ionic conductors in tellurite oxide glasses, these cations have the same charge but different size, electronic configuration and, in addition, their electric behavior is quite different. We show that the jump in the Cp at Tg is also related to the nature of the modifier cation. We study the conventional view of the configurational entropy of liquid that is frozen below the glass transition temperature (Tg) with what is called entropy loss. We explore whether or not there is a relationship between the nature of the modifier oxide and its magnitude. Fil: Cardillo, Evangelina Cinthia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: Terny, Cintia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina

It has been proposed that disk-like micelles may be precursors to the formation of lamellar liquid crystals. The possibility of obtaining n-decane phosphonic acid (DPA) disklike micelles in aqueous solution without the addition of a second ionic surfactant led us to study in detail the low-concentration range of this system by both a battery of experimental techniques and molecular dynamics (MD) simulations. The experimental results indicate that premicelles with some capacity to solubilize dyes are formed at 0.05 mM. The critical micelle concentration (cmc) was found to be 0.260 ± 0.023 mM, much lower than that previously reported in the literature. Spherical micelles, which immediately grow, leading to disk-like micelles, are probably formed at this concentration. At 0.454 ± 0.066 mM, disk-like micelles become unstable, giving rise to the formation of an emulsion of lamellar mesophase that dominates the system beyond 0.670 ± 0.045 mM. These experimental results were corroborated by MD simulations which, additionally, allow describing the structure of the obtained micelles at atomic level. The analysis of the MD trajectories revealed the presence of strong intermolecular hydrogen bonds between the surfactant headgroups, producing a compact polar layer with low water content. The formation of such H-bond network could explain the ability of this surfactant to form disk-like micelles at concentrations close to the cmc. Fil: Schulz, Erica Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: Piñeiro, Angel. Universidad de Santiago de Compostela. Departamento de Física Aplicada; España Fil: Rodríguez, José Luis Mariano. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina Fil: Minardi, Rosanna Marina. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: Schulz, Pablo Carlos. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina

The aggregation properties of 2-, 3-, and 4-fluorobenzoic acids (2FBA, 3FBA, and 4FBA, respectively) and their salts with hexadecyltrimethylammonium cations (HTA2FB, HTA3FB, and HTA4FB) in water were studied with a battery of techniques. Their activity at the air/solution interface has been also studied. The position of the fluorine atom in the acid affected the solubility, adsorption, and aggregation in the pure acids solutions. The 4FBA is less water soluble, more hydrophobic, and has the lower critical aggregation concentration of the three isomers. The behavior of the HTA2FB compound in aqueous solution is different from that of HTA3FB and HTA4FB. The critical micelle concentration, critical concentration for sphere-to-rod-like micelle transition, and Krafft point of HTA3FB and HTA4FB are lower than those of the other surfactant but their surface activities are higher. The differences between the HTA2FB and the other two surfactants have been explained on the basis of the regular solution theory of mixed micelles and in light of the analysis of the hydration shell of the acids through molecular dynamic simulations. The results of the present work suggest that the different behaviors are due to a combination of different dehydration tendencies and the steric possibility of inclusion of the counterions in the micelle palisade layer. The formation of rod-like micelles by HTA2FB, while the tetradecyltrimethylammonium 2-fluorobenzoate only forms spherical aggregates, is explained on the basis of the packing parameter. The mentioned factors are complementary to others presented in literature. These conditions may be used in the rational design of micelles by means of molecular dynamics simulations, reducing the trial-and-error approach used to date.

In the context of the ionic transport in glasses, the concept of conduction channels (or pathways) has proved to be useful to rationalize both experimental and computational results. While the concept of a transport “channel” is well defined for crystalline solid conductors, for the case of glasses this concept mainly refers to a finite region of the sample (at least in the diffusive time scale) in which mobile ions have a convenient environment to perform the electrical transport. In the previous work, we present an alternative way to put into evidence the existence of such regions in the diffusion time scale during a molecular dynamics experiment. In fact in that work [1] we use the so-called isoconfigurational ensemble method (ICEM) and the associated concept of particle propensity, both recently introduced by Harrowell and co-workers [2]. Then the notion of particle propensity to movement—immerse in the ICEM—was employed to find the existence of regions which are dynamically more active for the moving particles: the conduction channels. In the present paper we provide more computational evidence to support our alternative way to make evident the existence of channels that we presented in [1] : we show in this paper that our procedure is exactly equivalent to the approach previously adopted by other authors in the literature. This coincidence between the two searching strategies allow us to add more information about the nature of the channels. In fact, we can state now for the first time that the existence of the channels is defined at the very beginning of the dynamics and they remain almost unchanged even in the diffusive (nanosecond) scale. Besides, it was shown that a channel is a region of a sample which is also highly correlated dynamically during the trajectory of the moving ions.

We study the structure and orientation of water molecules at model hydrophobic surfaces by means of molecular dynamics. We focus here on the role of geometry in water hydration by comparing the situation for a planar graphene sheet with convex surfaces with different curvature: the exterior surfaces of carbon nanotubes and fullerenes of different radii. In all cases, we find the first water hydration layer to be more structured than the bulk. Additionally, the first water layers are found to be well oriented with respect to the surface normal in a way consistent with a local Ice Ih-like structuring, but differently form the water-air interface (along the opposite direction with respect to ice Ih basal plane). We also show that as the curvature of the surface gets more pronounced, the water molecules get less structured and oriented. This monotonic loss of local structure for proximal water represents a smooth tendency whenever we deal with an extended surface. However, when the surface becomes partially or completely non-extended (within the sub-nanometric regime), the surface water layer becomes to quickly lose structuring and orientation. Fil: Alarcon, Laureano Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Malaspina, David Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Schulz, Erica Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Appignanesi, Gustavo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

By means of molecular dynamics simulations we study the structure and dynamics of water molecules in contact with a model hydrophobic surface: a planar graphene-like layer. The analysis of the distributions of a local structural index indicates that the water molecules proximal to the graphene layer are considerably more structured than the rest and, thus, than the bulk. This structuring effect is lost in a few angstroms and is basically independent of temperature for a range studied comprising parts of both the normal liquid and supercooled states (240K to 320K). In turn, such structured water molecules present a dynamics that is slower than the bulk, as a consequence of their improved interactions with their first neighbors.

Amiodarone aqueous systems at concentrations C

The use of the isoconfigurational method has enabled one to determine the existence of particles with high and low dynamic propensity (tendency to be mobile) and particles with preferred directionality for motion (directional particles) in supercooled liquids. On the other hand, dynamical studies have shown that the relaxation of such systems evolves by means of rapid crossings between metabasins of the potential energy surface (a metabasin being a group of mutually similar, closely related structures which differ markedly from the ones belonging to other metabasins), as collectively relaxing units (d-clusters) take place. Here we determine the spatial arrangements of such particles in a model three dimensional glass-forming system. We show that both the highest and the lowest propensity particles form compact clusters, which are separated from each other by the high directionality particles. The particles of this interfacial region seem to behave as to help make room for the enhanced (expansion) movement of the high propensity cluster and to keep the local density constant. Finally, we also find that only the high propensity particles (but not the directional ones) exhibit a great tendency to take part in d-cluster events.

The aim of the present paper is to give structural information in order to set a correlation between the electrical conductivity behavior and structures of lithium and silver vanadium-tellurite based glasses. We report our structural studies and compare the effect of the nature of the metallic cation on glasses of the form XM2O · (1 - X)V2O5 · 2TeO2 (where 0 ≤ X < 1 and M = Li or Ag). Fourier transform infra-red (FTIR) spectra were recorded for all compositions and complementary differential scanning calorimetry (DSC) measurements and X-ray diffraction (XRD) measurements were also carried out. This paper should be considered as complementary to a previous article reporting the conductive behavior of theses glasses. In the latter we reported the obtained results on electrical conductivity studies. The results confirm the existence of a transition from a typically electronic (polaronic) conductive regimen when the molar fraction (X) of M2O is equal to 0, to an ionic conductive regimen when X tends to 1. The evidence for the independent migration path for both electrons and ions was put into evidence by studying the electrical conductivity behavior in a complementary system of the form X M2O · (1 - X)[0.5V2O5-0.5MoO3] · 2TeO2. In this system vanadium was partially replaced by molybdenum which acts as a 'diluting' agent of the active centers involved in the electronic transport. Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Quinzani, Oscar Valentín. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Pettigrosso, Rosa Susana. Universidad Nacional del Sur. Departamento de Química; Argentina Fil: Villar, Marcelo Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química; Argentina Fil: Montani, Ruben Alfredo. Universidad Nacional del Sur. Departamento de Química; Argentina

In this work, we assess the relevance of different range particle displacements and string motions to the metabasin (MB) dynamics of a simple glass former. We find that MB transitions are triggered by the occurrence of massive rearrangements termed as "democratic clusters" or d-clusters which last on average less than 1% of the α-relaxation time. Thus, at variance from previous investigations that focused on large displacements and strings, our work points to the essential role of medium-range particle displacements: we find that d-clusters are compact objects since the local neighborhoods of the most mobile particles exhibit significant rearrangements with a clear prevalence of medium-range displacements (of around 20% of the interparticle distance). This is in contrast to the string-like movements for which we demonstrate that many of them fully develop in isolation (their local environment being mostly insensitive to them) and at times different from that of MB transitions, being thus irrelevant to the α-relaxation. Additionally, from the analysis of the MB dynamics, preliminary support to the dynamics facilitation scenario is provided. Fil: Appignanesi, Gustavo Adrian. Universidad Nacional del Sur. Departamento de Química. Laboratorio de Fisicoquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina Fil: Frechero, Marisa Alejandra. Universidad Nacional del Sur. Departamento de Química. Laboratorio de Fisicoquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Alarcon, Laureano Martin. Universidad Nacional del Sur. Departamento de Química. Laboratorio de Fisicoquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

The blocking of ion transport at interfaces strongly limits the performance of electrochemical nanodevices for energy applications. The barrier is believed to arise from space-charge regions generated by mobile ions by analogy to semiconductor junctions. Here we show that something different is at play by studying ion transport in a bicrystal of yttria (9% mol) stabilized zirconia (YSZ), an emblematic oxide ion conductor. Aberration-corrected scanning transmission electron microscopy (STEM) provides structure and composition at atomic resolution, with the sensitivity to directly reveal the oxygen ion profile. We find that Y segregates to the grain boundary at Zr sites, together with a depletion of oxygen that is confined to a small length scale of around 0.5 nm. Contrary to the main thesis of the space-charge model, there exists no evidence of a long-range O vacancy depletion layer. Combining ion transport measurements across a single grain boundary by nanoscale electrochemical strain microscopy (ESM), broadband dielectric spectroscopy measurements, and density functional calculations, we show that grain-boundary-induced electronic states act as acceptors, resulting in a negatively charged core. Besides the possible effect of the modified chemical bonding, this negative charge gives rise to an additional barrier for ion transport at the grainboundary. Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Complutense de Madrid; España Fil: Rocci, M.. Universidad Complutense de Madrid; España Fil: Sanchez Santolino, G.. Universidad Complutense de Madrid; España Fil: Kumar, Amit. Oak Ridge National Laboratory. Center for Nanophase Materials Sciences; Estados Unidos Fil: Salafranca, Juan. Universidad Complutense de Madrid; España Fil: Schmidt, Rainer. Universidad Complutense de Madrid; España Fil: Diaz Guillen, M.R.. Universidad Complutense de Madrid; España Fil: Durá, O. J.. Universidad Complutense de Madrid; España Fil: RiveraCalzada, A.. Universidad Complutense de Madrid; España Fil: Mishra, R.. Vanderbilt University; Estados Unidos Fil: Jesse, Stephen. Oak Ridge National Laboratory. Center for Nanophase Materials Sciences; Estados Unidos Fil: Pantelides, S.T.. Vanderbilt University; Estados Unidos Fil: Kalinin, Sergei. Oak Ridge National Laboratory. Center for Nanophase Materials Sciences; Estados Unidos Fil: Varela, M.. Universidad Complutense de Madrid; España Fil: Pennycook, Steve. University Of Tennessee; Estados Unidos Fil: Santamaria, J.. Universidad Complutense de Madrid; España Fil: Leon, C.. Universidad Complutense de Madrid; España

We evaluate the distribution of female physicists in the Argentinean workforce, analyzing the distribution of women at different levels of education and research using several indicators. Although important imbalances still occur, our findings are encouraging and the distribution of female physicists seems to be changing for the better. Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Amador, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina Fil: Ramirez Pastor, Antonio Jose. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Física; Argentina Fil: Tamarit, Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina

From the results of molecular dynamic simulations of lithium metasilicate glass - at temperatures above and below their transition temperature (Tg ) - we propose a simple graphical representation to search for the broken ergodicity in an ionic oxide glass. Knowing whenergodicity is lost is critical for the proper use of statistical mechanics as a tool for measuring dynamical and structural properties through molecular dynamic simulation. This work shows how an abrupt qualitative transformation occurs in the way the system explores itspossible states when it goes down below the glass transition temperature range. We revise the broken ergodicity phenomena through its relationship with the observation time and the dynamic diversity of their atoms. Fil: Balbuena, Cristian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: Montani, Ruben Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina

In this paperwe present the study of the glassy systems of formula: xMgO(1−x)(0.5V2O5·0.5MoO3)2TeO2,with (0 b x b 1). The aim of the work is to understand the relationship between in the induced changes in the glassy matrix by the incorporation of MgO in a vanadium–tellurite glass and the electrical response of the material. It has been found that the incorporation of MgO in the glassy matrix raises the glass transition temperature. The whole system's electrical behavior is explained by the small polaron hopping, in good agreement with the variable range polaron hopping model. In this matrix, an ionic transport by Mg2+ is not allowed. The study gives an opportunity to understand how to tune in the middle-range glassy structural order and, as a direct implication, how to control the electrical conduction process., Instituto de Física La Plata

The electrical properties of mixed ion-polaron conducting vanadium tellurite glasses of the form XLi2O·(1 - X)[0.5V2O5·0.5MoO3]2TeO2 have been studied by using the impedance spectroscopy in a wide range of temperature and composition. The obtained results confirm the existence of a transition from a typically electronic (polaronic) conductive regime when the molar fraction (X) of Li2O is equal to 0, to an ionic conductive regime when X tends to 1. This transition is characterised by a deep minimum in the electrical conductivity of about 3 orders of magnitude. The correlated behaviour between conductivity and the mean distance between lithium ions and between vanadium ions reinforces the key idea of two independent migrating paths for both electrons and ions, respectively. Fil: Montani, Ruben Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

Within the landscape approach the dynamical heterogeneities presented by model glasses at low temperatures have been shown to represent well-defined elemental activated events in the exploration of the potential energy surface, PES. This last picture relies on the validity of a timescale separation hypothesis: Transitions within basins of attraction or Inherent Structures, ISs, of the PES must be fast compared to transitions between ISs. Additionally, ISs might be grouped in metabasins, MBs, the transition between them involving infrequent large scale rearrangements. In this work we clearly demonstrate the MB superstructure of the PES and study the T dependence of the MB dynamics. We find that beyond certain T timescale separation begins to break down both at the IS and the MB levels, which implies the cessation of the prevalence of activated dynamics as the system loses complexity, diversity and glassiness. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The landscape paradigm has become a widespread picture within the realm of complex systems. Complex systems include a great variety of systems, ranging from glasses to biopolymers, which display a common dynamical behavior. Within this framework, the dynamics of a such a system can be envisioned as the search it performs on its (potential energy) landscape. This approach rests on the belief that the relaxation behavior depends only on generic features, irrespective of specific details and lies on the validity of a timescale separation scenario computationally corroborated but not properly validated yet form first principles. In this work we shall show that the prevalence of activated dynamics over other kinds of mechanisms determines the emergence of complex dynamical behavior. Thus, complexity and diversity are not intrinsic properties of a system but depend on the kind of exploration of the landscape. We shall focus mainly on an ample generic context (complex hierarchical systems which have been used as models of glasses, spin glasses and biopolymers) and a specific one (model glass formers). For the last case we shall be able to reveal (in mechanistic terms) the microscopic rationale for the occurrence of timescale separation. Furthermore, we shall explore the connections between these two up to now mostly unrelated contexts and the relation to a variational principle, and we shall reveal the conditions for the applicability of the landscape approach. Fil: Appignanesi, Gustavo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Alarcon, Laureano Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Rodriguez Fris, Jorge Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Montani, Rosana A.. Universidad Nacional del Sur. Departamento de Química; Argentina

We perform a series of molecular dynamics simulations in a binary Lennard-Jones system at temperatures close to its mode-coupling temperature, T c . We demonstrate that the string-like movements carried out by a fraction of the particles are of ballistic nature. Depending on temperature these ballistic strings are found to become rare events related to free-volume effects on the sample. These facts point to a mechanistic description of the transport process and enables us to provide a microscopic reason for the occurrence of timescale separation.

In this work we investigate by means of molecular dynamics simulations the detailed time evolution of string-like cooperative motions in a binary Lennard–Jones system at temperatures close to its mode-coupling temperature, Tc. The strings will be fully geometrically and dynamically characterised, making evident the correlated and concerted nature of the motions of the particles comprised. We shall show that at low temperature each string occurs in a sharp time window within the time interval [0,t ∗ ] , where t ∗ is a characteristic time related to the lifetime of the global clusters of mobile particles. Moreover, the different strings that comprise a given global cluster will be shown to take place independently and asynchronically, thus providing further support to the heterogeneous scenario of relaxation, but in which different independent string-like sub-regions relax at different timescales. Finally, we shall also demonstrate that as temperature is increased the strings evolve during an increasing fraction of the time interval [0,t ∗ ] and that for T∼0.55 the lifetimes of the strings and of the global clusters become akin to each other.

We present a study of the nearly constant loss regime in the oxide-ion conductor Gd2Zr2O7 by using Impedance Spectroscopy measurements. At enough low temperature, between 173 and 253 K, the dielectric loss is found to be almost temperature and frequency independent within the whole experimental frequency range (10 Hz – 1 MHz). However, a symmetric and very broad relaxation peak is clearly resolved in the loss spectra. This peak shows a thermally activated peak frequency with activation energy Eτ = 0.29 ± 0.02 eV, and its origin is discussed in terms of previously proposed models for the nearly constant loss. Fil: Diaz Guillen, M. R.. Universidad Complutense de Madrid; España. Instituto de Investigaciones Eléctricas; México Fil: Frechero, Marisa Alejandra. Universidad Complutense de Madrid; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Diaz Guillen, J. A.. Instituto Tecnológico de Saltillo; México Fil: Fuentes, A. F.. Cinvestav Unidad Saltillo; México Fil: Leon, C.. Universidad Complutense de Madrid; España

In this work, we suggest an explanation of the electrical conductivity behavior of tellurite glassy systems modified with barium when transition metal oxides (V2O5-MoO3) present in the glassy matrix are replaced progressively by barium oxide. These glasses of formula x BaO (1 − x)(0.5 V2O5· 0.5 MoO3)2 TeO2 are obtained by the standard quenching technique and analyzed by means of impedance spectroscopy. We also report some structural results that explain the effect of the bivalent cation (Ba+2) on the electrical response in comparison to the effect of univalent cations on this kind of glassy matrix. The results confirm the existence of a transition from a typical hopping of small polarons response (when the content of BaO is low) to a weak ionic conductive response (when more than 50% of the transition metal oxides content has been replaced by BaO). The independent migration path is suggested by the observed electrical conductivity behavior. In this system, vanadium gives the active centers responsible for the polaron hopping mechanism while barium cations seem to be responsible for the ionic transport regimen. Fil: Terny, Cintia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Cardillo, Evangelina Cinthia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Di Pratula, Pablo Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Villar, Marcelo Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahia Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

We compute for an archetypical glass-forming system the excess of particle mobility distributions over the corresponding distribution of dynamic propensity, a quantity that measures the tendency of the particles to be mobile and reflects the local structural constraints. This enables us to demonstrate that, on supercooling, the dynamical trajectory in search for a relaxation event must deal with an increasing confinement of relaxation pathways. This "entropic funnel" of relaxation pathways built upon a restricted set of mobile particles is also made evident from the decay and further collapse of the associated Shannon entropy. Fil: Rodriguez Fris, Jorge Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: Appignanesi, Gustavo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina

Surprisingly, there is not a complete and general working theory for the ionic conduction on structurally disordered inorganic solids at present. In this context, lithium metasilicate glasses appear as paradigmatic and they have been extensively used for investigation in order to identify the main ingredients for a working theory of ionic conducting glasses. In particular among one of these main ingredients, the interaction among the mobile cations appears relevant, especially after recent results showing the existence of preferred pathways for ionic migration. We have performed Molecular Dynamics simulations on lithium metasilicate to better understand the ion-ion interactions. We introduce a very useful tool developed by Harrowell and co-workers (2004) to study propensity to movement and the use of the Pearson´s coefficient to characterize the correlation among the different kinds of ion. Our study allows us to support - from an alternative point of view - the idea of a landscape of energy for lithium ions with high propensity to movement (which eventually belongs to a high propensity cluster as defined in our previous work) and strongly dependent on the interaction among them. On the contrary, in the same window of time, these lithium ions do not strongly correlate with their nearest oxygen ions. Fil: Balbuena, Cristian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: Montani, Ruben Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina

Data collected 10 years ago in Argentina concluded that women in physics were underrepresented in many instances and that a “crystal ceiling” was firmly in place. We have collected updated data for several indicators and compared them with those obtained 10 years ago. Although there is not a clear conclusion to be drawn from this comparison, we try to explain the results within the framework of the changes in scientific policies in Argentina. Fil: Brudny, Vera Leonor. Universidad de Buenos Aires. Departamento de Ciencias Exactas; Argentina Fil: Lagorio, Cecilia. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata; Argentina Fil: Frechero, Marisa Alejandra. Universidad Nacional del Sur. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina Fil: Tamarit, Francisco. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Física "Enrique Gaviola"; Argentina

En este trabajo se presentan resultados de medidas de espectroscopia de impedancias realizadas en un bicristal del conductor iónico zirconia estabilizada con itria (YSZ). Utilizando electrodos de tamaño micrométrico se ha podido medir el transporte iónico a través, perpendicularmente, de una única frontera de grano, caracterizando eléctricamente las propiedades de dicha frontera. De este modo se han obtenido los parámetros microscópicos que determinan la distribución de carga en la frontera y por lo tanto el transporte iónico a través de ella, como son la barrera de potencial en la frontera DF = 0.35±0.01 V a 275 ºC, y el espesor de la zona de carga espacial l* = 5±1 Å. Estos valores son significativamente diferentes a los obtenidos anteriormente en muestras cerámicas policristalinas del mismo material, y muestran mejor acuerdo con los valores que predice el modelo de Mott-Schottky para la distribución de carga y el transporte iónico a través de la frontera de grano. Here we show impedance spectroscopy measurements on a bicrystal of the ionically conducting yttria stabilized zirconia (YSZ). By using micrometer sized electrodes it is possible to measure ionic transport perpendicular to a single grain boundary, and characterize its electrical properties. We are thus able to obtain the microscopic parameters that determine the charge distribution at the grain boundary and the ionic transport through it, as the potential energy barrier DF = 0.35±0.01 V at 275 ºC, and the space charge layer thickness l* = 5±1 Å. These values are significantly different from those previously obtained in polycrystalline ceramic samples of the same material, and show much better agreement with the values predicted by the Mott-Schottky model for the charge distribution and ionic transport through the grain boundary Fil: Frechero, Marisa Alejandra. Universidad Complutense de Madrid; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Rocci, M.. Universidad Complutense de Madrid; España Fil: Schmidt, R.. Universidad Complutense de Madrid; España Fil: Diaz Guillen, M.. Universidad Complutense de Madrid; España Fil: Dura, O.. Universidad Complutense de Madrid; España Fil: Rivera Calzada, A.. Universidad Complutense de Madrid; España Fil: Santamaria, J.. Universidad Complutense de Madrid; España Fil: Leon,C.. Universidad Complutense de Madrid; España

We present ac conductivity spectra of telluritie glasses at several temperatures. For the first time, we report oscillatory modulations at frequencies around MHz. This effect is more pronounced the lower the temperature, and washes out when approaching the glass transition temperature Tg. We show, by using a minimal model, how this modulation may be attributed to the fractal structure of the glass at intermediate mesoscopic length scales. Fil: Frechero, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: Padilla, Lorena. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata; Argentina Fil: Martin, Hector Omar. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata; Argentina Fil: Iguain, Jose Luis. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata; Argentina