Search

El sector económico de las Mipymes presenta oportunidades y desafíos de gran relevancia para el desarrollo económico paraguayo y es de suma importancia el estudio de su realidad, así como su fortalecimiento. Este contexto como producto de una caracterización poblacional realizada en el marco de una investigación académica, la Facultad de Ciencias Económicas de la Universidad Nacional de Asunción vio la necesidad de desarrollar un programa de extensión universitaria denominado Núcleo de Asistencia Empresarial (NAE) como un espacio desde donde la academia, a través de docentes tutores y estudiantes pueda brindar al sector empresarial la asesoría necesaria para hacer crecer a la empresa y generar un compromiso de vinculación permanente. El campo de actuación del NAE no solo es en la ciudad de San Lorenzo, sino que se extiende al interior del país en la búsqueda de que la FCE cumpla con una función social práctica de ayuda social en los espacios donde se le requiera y, al mismo tiempo, de lograr un entrenamiento profesional de sus estudiantes. El presente trabajo tiene como objetivo general determinar la incidencia en la formación de habilidades blandas en las Mipymes asistidas en el periodo 2020-2021. La investigación inició con el nivel exploratorio para conocer todo lo concerniente a las Mipymes y las asesorías que reciben; en la fase bibliográfica documental se dio lugar a la revisión, verificación, y clasificación de fuentes secundarias acerca del tema. Dentro de los registros obtenidos durante el periodo del año 2020 al 2021, se tiene en existencia un total de 152 microempresarios asistidos a quienes se les capacitó en creatividad, innovación, el liderazgo, la comunicación; además se les entrenó en la identificación de costos de producción, presupuesto empresarial y finanzas personales.

La pancreatitis aguda es un proceso inflamatorio agudo del pancreas, ocasionado por la activacion alterada de las enzimas pancreaticas, con lesion tisular, respuesta inflamatoria local, y compromiso variable de otros tejidos o sistemas organicos distantes. Es habitualmente un proceso reversible. La litiasis biliar y el alcohol representan un elevado porcentaje de los casos descritos en las fuentes consultadas. Otras etiologias menos frecuentes son: cirugias, traumatismo, infecciones, hiper trigliceridemia, farmacologicas, hipercalcemia, insuficiencia renal y post colangiopancreatografia retrograda endoscopica. El diagnostico de la pancreatitis aguda generalmente se realiza por la presencia de 2 de 3 de los siguientes criterios: dolor abdominal consistente con la enfermedad, amilasa o lipasa serica elevada mas de tres veces del limite superior normal e imagenes fuertemente sugestivas. El dolor usualmente es severo, se presenta en epigastrio o hipocondrio izquierdo con irradiacion a espalda o flancos. El uso de la profilaxis antibiotica en el manejo de la pancreatitis aguda, solo ha mostrado beneficio en casos de pancreatitis severa con necrosis del tejido pancreatico, definiendo la necrosis como zonas localizadas o difusas de tejido pancreatico no viable que, generalmente, se asocian a necrosis grasa peri pancreatica. En la tomografia se aprecian zonas con densidad menor que la del tejido normal pero mayor que la densidad liquida y que no incrementan su densidad con el medio de contraste. La administracion de antibioticos de amplio espectro con adecuada penetracion tisular, es necesaria para prevenir la infeccion en casos de pancreatitis aguda grave con necrosis pancreatica. La metodologia usada es descriptiva, con un enfoque documental, es decir, revisar fuentes disponibles en la red, como google academico, con contenido oportuno, actualizado y relevante desde el punto de vista cientifico que enriquezca el analisis del tema planteado en este articulo.

La complejidad del cuerpo humano y su funcionamiento requieren de las ciencias medica cada vez más se conduzcan hacia lo que se conoce como hiperespecialización, pero a su vez también ha permitido la expansión de este conocimiento hacia otras ciencias e incluso en muchas ocasiones se requiere de la colaboración de equipos multidisciplinarios para colaborar dentro de la medicina. Quizás uno de los campos que más expuesto se encuentra a esta multi e interdisciplinariedad sea la medicina oftalmológica. La oftalmología es precisamente el objeto de estudio de este libro, el cual fácilmente podría haber sido titulado introducción a la oftalmología, pues representa de manera sencilla pero rigurosa una introducción al mundo de la medicina oftalmológica. A través de estas páginas se podrá hacer un recorrido práctico y al mismo tiempo riguroso de todo aquello que compete a la oftalmología como ciencia médica. Se encuentra dividido en cuatro capítulos, el capítulo I y II están dedicados a comprender como la oftalmología se constituye como ciencia dentro del campo de la medicina, en este sentido se relata la historia de la oftalmología, además de definirla y explicar su importancia para las ciencias médicas, de igual manera se define de manera concreta el perfil no solo del médico oftalmólogo sino también de los profesionales que también trabajan en el campo sin ejercer la medicina y funcionan como auxiliares para el médico oftalmólogo.

The present work addresses university extension as an interactive link with society. A bibliographic review was made about the beginning as a substantive function of the universities and their incorporation into the National University of Asunción of Asunción (UNA) is described as one of their purposes along with research and teaching. The documentary review of the development of the university extension in the Faculty of Economic Sciences (FCE) was continued, supported by secondary sources, especially in the reports of activities and institutional documents kept in the Extension and Services Directorate. As results are identified the advances, as well as the specific experiences in the development of the university extension that gave origin to the creation of the University Office in Accounting, Administration and Economic (CUCAE) to strengthen the link between the Paraguayan society and the educational community of the FCE. The methodology to be used is the qualitative, documentary - bibliographic type that aims to highlight the importance of university extension as a substantive function and its focus on promoting two-way interaction activities in scenarios where students offer solutions to problematic situations. it enriches the university and society in general.

The process of equilibration of the tetradecane-water interface in the presence of sodium hexadecane-benzene sulfonate is studied using intensive atomistic molecular dynamics simulations. Starting as an initial point with all of the surfactants at the interface, it is obtained that the equilibration time of the interface (several microseconds) is orders of magnitude higher than previously reported simulated times. There is strong evidence that this slow equilibration process is due to the aggregation of surfactants molecules on the interface. To determine this fact, temporal evolution of interfacial tension and interfacial formation energy are studied and their temporal variations are correlated with cluster formation. To study cluster evolution, the mean cluster size and the probability that a molecule of surfactant chosen at random is free are obtained as a function of time. Cluster size distribution is estimated, and it is observed that some of the molecules remain free, whereas the rest agglomerate. Additionally, the temporal evolution of the interfacial thickness and the structure of the surfactant molecules on the interface are studied. It is observed how this structure depends on whether the molecules agglomerate or not.

Acral lentiginous melanoma (ALM) is a rare variety of melanoma typically located on distal areas of the body. Due to its presentation, it can be confused with a vascular ulcer.The authors present the case of a 68-year-old man who smokes with a history of hypertension, diabetes, and dyslipidemia, who was referred to the vascular clinic with complaints of intermittent claudication and a developing ulcer on his heel. After formulating an accurate wound care plan and performing revascularization surgery, the ulcer did not heal. At this point, the wound was biopsied and melanoma diagnosis was confirmed. After melanoma surgery, direct closure of the wound with a split-thickness skin graft was performed.Despite its rare pathology, misdiagnosis of ALM may prolong initiation of appropriate treatment and reduce the overall survival rate. Biopsies should be performed on nonhealing ulcers despite appropriate wound management and/or revascularization procedures.

The electron density localization in insulator and semiconductor elemental cubic materials with diamond structure, carbon, silicon, germanium, and tin, and good metallic conductors with face centered cubic structure such as α-Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au, was studied using a localized electrons detector defined in the local moment representation. Our results clearly show an opposite pattern of the electron density localization for the cubic ceramic and transition metal materials. It was found that, for the elemental ceramic materials, the zone of low electron localization is very small and is mainly localized on the atomic basin edges. On the contrary, for the transition metals, there are low-valued localized electrons detector isocontours defining a zone of highly delocalized electrons that extends throughout the material. We have found that the best conductors are those in which the electron density at this low-value zone is the lowest.

X-ray diffraction,27Al MAS NMR, and FTIR spectra along with results of molecular dynamics simulations were used to characterise LaxEu1−xAlO3perovskites forx=0.3, 0.1. Experimental and simulation results show that local changes in the perovskite-like structure can be achieved as lanthanum ions substitute europium ones. The introduction of La3+ions in the EuAlO3parent causes an increase in the mobility of oxygen network.

The structural and electronic features of the interaction between silica surfaces and surfactants have been studied with high level computational techniques of simulation. Calculations have been performed at the B3LYP level of theory as implemented in the CRYSTAL06 code. Each of the periodic models adopted consists of a conveniently functionalized (001) surface of edingtonite and a layer of tetrametilammonium and other species like water and Cl− that mimic the interface between the silica and the surfactant solution moieties, in both acidic and basic media. Different degrees of coverage and hydration have also been considered. Our calculations indicate that besides the electrostatic interactions, polarization and charge-transfer processes play a nonnegligible role in the formation and stability of the silica surface.

Strontium containing LaAlO 3 perovskites, (La,Sr)AlO 3 , were prepared by co-precipitation method. 20% of lanthanum was replaced by strontium into LaAlO 3 . Structural characterization of materials through XRD and NMR techniques suggests that Sr introduction causes that unsaturated aluminum, Al IV and Al V appear in decrement of the amount of Al VI . This result was confirmed by molecular dynamics simulations and a mechanism of the formation of the unsaturated aluminum is given.

A realistic model, consisting of six-layer slabs, and density-functional calculations were used to perform a detailed analysis of the structural and electronic properties of N doped TiO2(110). All the positions examined for adsorption of atomic N are unstable regarding the formation and further escape of N2(g). The adsorption of atomic N could take place only when having isolated adatoms. In this case, N prefers to bond to O centers located either on the surface or in the interstitial channels of the oxide lattice. These N adatoms probably give rise to the peak seen at ∼400 eV in N 1s XPS spectra. The coexistence of N with O vacancies and surface reconstructions are explained in terms of cooperative behaviors and the special electronic structure of the TiNxO2-2x(110) system. Here, electrons move from the O vacancies to implanted N to fill up its electronic shell. Such electron transfer yields the normal oxidation state of nitrogen, N3-, and explains a number of things: the easiness to form O vacancies wh...

Assume that K independent copies are made from a common prototype DNA sequence whose length is a random variable. In this paper, the problem of aligning those copies and therefore the problem of estimating the prototype sequence that produced the copies is addressed. A hidden Markov chain is used to model the copying procedure, and a reversible jump Markov chain Monte Carlo algorithm is used to sample the parameters of the model from their posterior distribution. Using the sample obtained, the Bayesian model and the prototype sequence may be selected using the maximum a posteriori estimate. A prior distribution for the prototype DNA sequence that incorporates a correlation among neighbouring bases is also considered. In addition, an analysis of the performance of the algorithm is presented when different scenarios are taken into account.

Exposure to high levels of pollution is a persistent problem in large cities throughout the world. The ability to predict the occurrence of a high level of a pollutant allows environmental authorities to take preventive measures, such as controlling the emission of pollution. Communities and officials can also take actions to reduce the exposure of susceptible groups in the population. Therefore, being able to estimate the behavior of a given pollutant is of great importance. In this article we use a Markov chain model to study this behavior. In order to do so, we consider the sequence of the daily maximum measurements of a pollutant and let successive intervals containing them follow a Markov chain of order K>-0. The novelty here is that we allow K to be a random variable and estimate it and the corresponding transition probabilities using a maximum a posteriori method. The results are used to perform estimations about the behavior of ozone levels in Mexico City.

The behavior of surface undercoordinated Al 3 + cations as electron acceptors is investigated by means of periodic ab initio calculations. The (0001) surfaces of α-Al 2 O 3 and AlN(w) were chosen as representative of the different Al coordination types. The electronic structure was analyzed through the valence localized Wannier functions that allow a straightforward description of the electron pairs in terms of chemical concepts. The relevance of the electron back-donation toward surface Al 3 + cations in the reconstruction of the surfaces is discussed, and evidence was found that some π-bond character is displayed by the surface Al-X bonds after relaxation. This explains the tendency to form surface Al-X planar layers in this kind of system.

Charge-transfer molecular dynamics simulations of AlN were performed in the microcanonical ensemble with a non-stoichiometric and defective system in order to achieve a realistic representation of the material. Structural properties and the infrared and nuclear magnetic resonance spectra were calculated. The results suggest that the degree of non-stoichiometry and the population of defects may produce considerable effects on the experimental studies using IR and 27 Al NMR techniques.

Molecular dynamics simulations have been conducted for a NaY zeolite and Li doped amorphous silica. These have enabled i) the experimentally derived 29Si MAS-NMR spectrum for the zeolite to be predicted with good accuracy (within 2%) and ii) the characterisation of local, environments in α-SiO 2 and the nature of oxygen moeties in the Li-Si-O system to be elucidated. These theoretical analyses have required the use of charge distribution effects which have been developed during this work.

The characteristic 29 Si NMR spectrum of silicalite has been obtained through charge-transfer molecular dynamics, in order to assign each resonance line to a specified tetrahedral site through its charge. From the simulation, the charge distribution on each of the non-equivalent silicon tetrahedral sites has been determined. A relationship between charge and chemical shift has been used to relate any resonance line to a specified tetrahedral site through its charge. It has been observed from the simulation that several tetrahedral sites can contribute to a single line in the spectrum.

A new way to interpret the infrared spectra of transition aluminas in the OH as well as in the AlO stretching spectral region is proposed. It takes into account the recent and key progresses made possible by different techniques of 27 Al high resolution NMR spectroscopy as well as by the application of molecular dynamics. The fundamental principle is the consideration of Al atom pairs. These Al atoms have all possible coordinations with respect to oxygen. A distinction between the bulk and surface phase’s contributions is possible. The predictive power of this new approach is emphasized.

Charge-transfer molecular dynamics simulations of NaY zeolite in thermodynamical equilibrium in the microcanonical ensemble were carried out in order to obtain the charge distribution of all charge-transferring species. The interaction potentials used were parameterised ab initio calculations and take into account the Al–O and Si–O partially covalent bonds. The different kinds of O and Si atoms are characterised based on their charge distributions which are comparable with experimental 29 Si MAS NMR data.

Molecular dynamics simulations of Li2O were performed in the microcanonical ensemble at several diAerent temperatures in order to study the lithium diAusion process, and a preliminary exploration of the diAusion of tritium was performed. DiAerent Li/O molar ratios were used to investigate the role of non-stoichiometry in the Li diAusion processes. The mechanism of lithium diAusion as a function of temperature is proposed based on the analysis of our simulations and a model is proposed to explain the overall behaviour of the lithium diAusion coeAcient as a function of temperature. Our simulations suggest what is the role of hydrogen in the tritium release from breeder ceramic materials. ” 2000 Elsevier Science B.V. All rights reserved.

Experimental characterization of grain and grain boundaries of chromia scales upon addition of La has been carried out with a variety of techniques. The effect of lanthanum addition on the high temperature oxidation is explained based on simulations suggested by the experimental results. The grain boundary precipitation mechanism of perovskite phases suggested by our simulations is through the extraction of Cr atoms from the oxide scale.

Molecular dynamics simulations in the microcanonical ensemble of liquid yttrium oxide were performed at a temperature of 3100 K. Three different Y/O ratios were used in order to find out what the role of nonstoichiometry is in the process of melting and disordering of the liquid at high temperatures. Our simulations indicate that when no oxygen vacancies are generated there is no disordering process and the crystalline structure should remain. We conclude that the melting process occurs, in the real system, when a large enough number of oxygen vacancies is generated as a result of the large thermal vibrations of superficial oxygen atoms. The apparent high coordination number for yttrium found experimentally is explained based on the overlapping of the partial radial distribution functions, which cannot be elucidated from the x-ray diffraction data but can be clearly seen from our simulations. @S0163-1829~99!08813-X#

Molecular-dynamics simulations of the (0001) surface of ${\mathrm{Cr}}_{2}{\mathrm{O}}_{3}$ were carried out in the [300--2800 K] range of temperatures using a classical Pauling-type pair potential. The analysis of the structural data shows a strong surface relaxation in agreement with experiment. Both static and dynamic surface properties indicate that a surface melting process occurs well below the melting point, which is estimated to be about 2500 K, in excellent agreement with the experimental value of 2556 K. The diffusive properties of this disordered phase are described and it is found that the main mechanism for diffusion involves hopping of surface atoms.

We present a variant of the “Swiss-cheese” model to allocate the maximum void volume in a simulated structure while minimizing the number of holes. The algorithm performance is not dependent upon user-adjustable parameters and there are no restrictions as to the type of target structure. A procedure to analyse connectivity in a structure, according to a criterion established here, is also presented. An alternate form of a percolation graph is suggested. The algorithms were tested on a simulated vitreous silica matrix, obtained by charge-transfer molecular dynamics. The results obtained in agreement with theoretical and experimental values regarding the percolation and gas-solubility behaviour of this structure.

The bulk and surface features of an alumina particle obtained by molecular-dynamics simulation are used to support the experimental distribution of aluminums with respect to their coordination number obtained by NMR (nuclear magnetic resonance). This information was obtained by using results of various editing procedures of the 27Al nuclear magnetic resonance, such as the classical one-pulse (1P) magic angle spinning, the cross polarization (CP) from the protons of chemisorbed ammonia and the 1P or CP rotational echo double resonance (REDOR). Because the REDOR technique revealed that the acid Lewis sites are constituted by pairs of four or fivefold coordinated aluminum atoms about 3 A apart, these pairs were counted in the simulated particle. The agreement with experimental surface density of Lewis sites is satisfactory.

Molecular dynamics simulations were used to study the bulk and {100} surface of LaAlO 3 . Bulk and surface structures and vibrational spectra are reported. Both the AlO 2 and LaO surface termination were studied. The LaO termination is clearly more stable than the AlO 2 termination.

Extraframework alumina in zeolites is considered by some authors to play a crucial role in the establishment of their reactivity. Charge transfer molecular dynamics simulations (CTMD) in the microcanonical ensemble of zeolite Y confirmed that catalytically active sites in zeolites are produced by the presence of extraframework alumina, and indeed, that it also is necessary to stabilize the zeolite lattice. In this work we present a plausible model for the formation of extra-framework alumina based on the results of CTMD simulations of a Y zeolite with compensation sodium cations, and give the physicochemical arguments for the stabilization role that it plays. The simulated system consisted of 653 particles representing 165 silicon atoms, 414 oxygen atoms, 47 aluminum atoms, and 27 sodium atoms. Radial distribution functions, the i.r. spectrum, and the n.m.r. predictions reproduced fairly well the corresponding available experimental data.

A set of molecular dynamics simulations in the microcanonical ensemble has been performed in order to study the diffusion of lithium in γ-LiAlO 2 , since this material is considered as candidate material for tritium breeder for fusion reactors. In this system tritium release and diffusion depends on the diffusion of lithium. Radial distribution functions, diffusion coefficient and activation energy for the process were determined from our calculations.

A set of twenty molecular dynamics simulations of the surface of γ-Al 2 O 3 were performed at different densities and temperatures in order to investigate the formation mechanisms and structure of micropore systems. It is found that a severe reconstruction takes place at high densities which involves ion migration and a partial amorphization process of the surface. At low densities a different process takes place which does not involve ionic migration but only a local atomic rearrangement. The statistics of size distribution and volume per unit mass calculated from the molecular dynamics simulations are within the ranges experimentally obtained and theoretically predicted.

Molecular-dynamics simulations using a Pauling type pairwise potential have been carried out in order to study the structure of the surface of γ-Al2O3. Starting from an ideal (100) face, a reconstruction process occurs in which the unbalanced coordination of surface ions tends to fulfill their coordination capabilities. Oxygen ions come to the surface and pore formation with a concomitant increase of apparent volume takes place. The structure of the surface of the resulting material corresponds to a porous amorphouslike phase in which only short-range order is present. Analysis of the radial distribution function agrees with experimental x-ray-diffraction data Comisión Interministerial de Ciencia y Tecnología PB92-0665 y PB92-0662 Junta de Andalucía AGCI-6006 y AGCI-1039

Molecular dynamics (MD) simulations ofγ-Al2O3, using a pairwise additive interaction potential of Pauling's type with four different radii for aluminum atoms, were analysed in order to determine the influence of the radius on the modification of coordination numbers of A1 relative to the ideal structure, at two different temperatures of 300 and 1500 K. It is found that the best choice is the radius of penta-coordinated aluminum, reproducing structural and vibrational properties of the compound in excellent agreement with experimentally observed properties.

Molecular dynamics simulations of the catalytic system constituted by La 2 O 3 supported on γ-Al 2 O 3 are reported. Our calculations show that increasing the lanthanum concentration in the solid causes a lowering of the vibrational frequencies associated with the Al-O stretch, in qualitative agreement with experiment

Molecular dynamics simulations of model systems for the surface interaction of lanthanum oxide supported on γ-alumina have been carried out at 1500 K. The onset of formation of perovskite-like phases has been analysed in samples containing four different concentrations of lanthanum oxide. A mechanism of the formation of perovskite-like polyhedra is proposed. This mechanism essentially involves a displacement of an oxide ion associated to an octahedral aluminum by a lanthanum ion and appears to be independent of La2O3 loadings.

Molecular dynamics simulations of ZnAl2O4 spinel have been carried out at 300 and 800 K. Comparison with experimental data shows that at low temperature the most favorable configuration is that of a mixed spinel. As temperature increases the structural transformation becomes more evident. A detailed interpretation of the experimental vibrational spectrum and radial distribution functions is obtained.

Molecular dynamics simulations for γ-Al2O3 and La3+-doped γ-Al2O3 crystals have been performed. From bulk simulations a description of the crystal-terminating layers in both doped and pure alumina solids is reported. The molecular dynamics simulations allow us to describe systematically for the first time the surface of the γ-Al2O3 crystal, taking into account the actual stoichiometry of the solid. This description results in a model in which the number of different surface sites is increased with respect to the previously reported models. The number of different surface sites may account for the IR spectra of hydroxy groups adsorbed on γ-Al2O3.

Molecular dynamics (MD) studies of γ-Al 2 O 3 using a pairwise additive interaction potential of Pauling's type are reported. MD simulations on a medium-sized cluster of γ-Al 2 O 3 (Al 576 O 864 ) show a picture of its structure which is in agreement with neutron diffraction results and lead to an interpretation of its main properties. MD simulations at several temperatures and velocity autocorrelation functions are also reported.

A scheme is described for the explicit treatment of charge-transfer processes in molecular-dynamics simulations of condensed phases. Technical details of the simulations are discussed, and it is shown that it is possible to implement the method without serious cost in computing time relative to standard molecular-dynamics calculations for charged systems. The scheme used ensures that the charge-transfer forces are dynamically conservative, and no numerical instabilities have been observed in the integration of the equations of motion. The method is applied to pure amorphous silica and to silica to which small numbers of dilithium oxide impurities have been added. The distributions of atomic charges have their expected form in each case. In particular, addition of the cation impurities leads to the spontaneous generation of an almost equal number of oxygen defects, and it is shown that it is possible to distinguish unambiguously between bridging and dangling oxygens on electrostatic rather than ge...

Because of the increase in life expectancy, peripheral artery disease (PAD) has become a major health problem. A study performed in Spain in persons aged more than 65 years old found an overall prevalence of PAD of 9.9%. The most important risk factors for PAD were smoking, diabetes mellitus, advanced age, hyperlipidemia and hypertension. Treatment includes smoking cessation, exercise, statins, platelet antiaggregants, cilostazol or hemorheologic agents, and revascularization techniques. Data from the Spanish arm of REACH indicate that the PAD subgroup shows the poorest control of blood pressure and cholesterol and that use of platelet antiaggregants and statins is lowest in these patients, indicating that therapeutic and preventive strategies are not being correctly applied.

A new vectorisable algorithm is proposed for identifying the triads of particles required in the calculation of three-body interactions. Tests of this algorithm on a glassy silicate show a five-fold reduction of CPU time per configuration with respect to a simple triple-loop procedure. The calculation of the three-body interactions, using the new algorithm, takes only 10% of the total CPU time of the simulation.

The total and partial radial distribution functions g(r) and the corresponding structure factors S(q) were calculated based on molecular-dynamics simulations in the microcanonical ensemble of liquid aluminum oxide. The simulations were performed in the temperature range 2300-3000 K in order to explore the temperature dependence of the structure, finding that the liquid structure is invariant as a function of temperature. With the aid of the partial radial distribution functions, it is possible to reinterpret the experimental data leading to a new assignment of peaks which differs from the one reported in a previously published work by Ansell et al. [Phys. Rev. Lett. 78, 464 (1997)]. The structural model for liquid aluminum oxide obtained from our simulations is essentially the same as that reported in the experimental work. Dirección General de Investigaciones Científicas y Técnicas PB95-1247

Charge-transfer molecular dynamics simulations of protonated faujasite have been carried out in the microcanonical ensamble. The parameters of the pair interaction potentials of some species have been obtained from ab-initio calculations and are able to reproduce the bond-making and breaking of the Si-O pair. The simulated system consisted of 653 particles of which 165 were silicon atoms, 414 oxygen atoms, 47 aluminium atoms and 27 hydrogen atoms. Structural and dynamical properties of the system are well reproduced and some insight into the location and formation mechanisms of acid sites is obtained.

A series of molecular dynamics simulations were performed in order to explore the initial (10.5 ns) structure of CTAB micelles formed in aqueous solutions. The determination of the aggregation number of CTAB is a long-standing and fundamental problem. Therefore we simulated eight model systems of micelles in aqueous solution. Some micellar structural characteristics, local solvation environments, and counter ion distributions are described. Topological and geometrical concepts are used to characterize the resulting micelle structures. Our findings indicate that for certain aggregation numbers micelles are formed by layered spherical structures.

The fundamental phenomena underlying the electrical conduction properties of Sr-containing LaAlO(3) perovskites are studied through DFT simulations. The most energetically favourable substitution sites for Sr in the LaAlO(3) lattice and the energetic barriers for oxygen diffusion were calculated. Ab initio molecular dynamics was used to investigate the onset of oxygen transport. Experimental characterization of this material has suggested the existence of undercoordinated Al atoms upon substitution of La with Sr. Our results confirm the existence of four- (Al(IV)) and fivefold (Al(V))-coordinated Al at the expense of the amount of sixfold-coordinated ones (Al(VI)), and explain the appearance of a small peak at 66 ppm in the (27)Al NMR spectrum.