Diffusion anomaly and dynamic transitions in the Bell-Lavis water model

In this paper we investigate the dynamic properties of the minimal Bell-Lavis (BL) water model and their relation to the thermodynamic anomalies. The Bell-Lavis model is defined on a triangular lattice in which water molecules are represented by particles with three symmetric bonding arms interacting through van der Waals and hydrogen bonds. We have studied the model diffusivity in different regions of the phase diagram through Monte Carlo simulations. Our results show that the model displays a region of anomalous diffusion which lies inside the region of anomalous density, englobed by the line of temperatures of maximum density (TMD). Further, we have found that the diffusivity undergoes a dynamic transition which may be classified as fragile-to-strong transition at the critical line only at low pressures. At higher densities, no dynamic transition is seen on crossing the critical line. Thus evidence from this study is that relation of dynamic transitions to criticality may be discarded

Dynamic Transitions in a Two Dimensional Associating Lattice Gas Model

Using Monte Carlo simulations we investigate some new aspects of the phase diagram and the behavior of the diffusion coefficient in an associating lattice gas (ALG) model on different regions of the phase diagram. The ALG model combines a two dimensional lattice gas where particles interact through a soft core potential and orientational degrees of freedom. The competition between soft core potential and directional attractive forces results in a high density liquid phase, a low density liquid phase, and a gas phase. Besides anomalies in the behavior of the density with the temperature at constant pressure and of the diffusion coefficient with density at constant temperature are also found. The two liquid phases are separated by a coexistence line that ends in a bicritical point. The low density liquid phase is separated from the gas phase by a coexistence line that ends in tricritical point. The bicritical and tricritical points are linked by a critical $\lambda$-line. The high density liquid phase and the fluid phases are separated by a second $\tau$ critical line. We then investigate how the diffusion coefficient behaves on different regions of the chemical potential-temperature phase diagram. We find that diffusivity undergoes two types of dynamic transitions: a fragile-to-strong trans ition when the critical $\lambda$-line is crossed by decreasing the temperature at a constant chemical potential; and a strong-to-strong transition when the $\tau$-critical line is crossed by decreasing the temperature at a constant chemical potential.Comment: 22 page

Hydration and anomalous solubility of the Bell-Lavis model as solvent

We address the investigation of the solvation properties of the minimal orientational model for water, originally proposed by Bell and Lavis. The model presents two liquid phases separated by a critical line. The difference between the two phases is the presence of structure in the liquid of lower density, described through orientational order of particles. We have considered the effect of small inert solute on the solvent thermodynamic phases. Solute stabilizes the structure of solvent, by the organization of solvent particles around solute particles, at low temperatures. Thus, even at very high densities, the solution presents clusters of structured water particles surrounding solute inert particles, in a region in which pure solvent would be free of structure. Solute intercalates with solvent, a feature which has been suggested by experimental and atomistic simulation data. Examination of solute solubility has yielded a minimum in that property, which may be associated with the minimum found for noble gases. We have obtained a line of minimum solubility (TmS) across the phase diagram, accompanying the line of maximum in density (TMD). This coincidence is easily explained for non-interacting solute and it is in agreement with earlier results in the literature. We give a simple argument which suggests that interacting solute would dislocate TmS to higher temperatures

Liquid polymorphism, order-disorder transitions and anomalous behavior : a Monte Carlo study of the Bell-Lavis model for water

The Bell–Lavis model for liquid water is investigated through numerical simulations. The lattice-gas model on a triangular lattice presents orientational states and is known to present a highly bonded low density phase and a loosely bonded high density phase. We show that the model liquid-liquid transition is continuous, in contradiction with mean-field results on the Husimi cactus and from the cluster variational method. We define an order parameter which allows interpretation of the transition as an order-disorder transition of the bond network. Our results indicate that the order-disorder transition is in the Ising universality class. Previous proposal of an Ehrenfest second order transition is discarded. A detailed investigation of anomalous properties has also been undertaken. The line of density maxima in the HDL phase is stabilized by fluctuations, absent in the mean-field solution

Intellectual Capital Change Management in the Construction Industry—The Case of an Inter-Organisational Collaboration

Nowadays, due to the complexity of the relationships with external entities, along with the importance that traditional media and the innovative social media have in creating competitive advantages, it is necessary for companies to collaborate in order to create Intellectual Capital (IC). Although collaboration is crucial to create IC, there is a paucity in literature regarding the effects that a specific type of collaboration may have on the IC of an organisation, specifically a franchising with a mediatic actor. Moreover, literature addressing IC creation and destruction over time is scarce, especially when applied to the construction industry. This paper’s goal is twofold: understanding the longitudinal changes of a construction SME’s Intellectual Capital, regarding its creation and destruction; analysing the impact that a specific inter-organisational collaboration franchising—with a mediatic actor may have on such IC. A single in-depth case study was conducted, allowing to conclude that the actions of an organisation can develop both Intellectual Assets and Intellectual Liabilities. It was also concluded that inter-organisational collaboration, through a franchise with an actor with experience in communication, can generate, in the long term, positive and innovative effects regarding the different IC components, namely the Relational one. More specifically, the paper allowed to ascertain that an organisation’s IC changes over time in a dynamic fashion, i.e., Intellectual Liabilities which emerged before an innovative collaboration can be transformed into Intellectual Assets and create competitive advantages. This paper contributes to stress the importance of managing IC, not only when it is created, but namely in when it can be destroyed, in a context of inter-organisational collaborations applied to a construction SMEinfo:eu-repo/semantics/publishedVersio

Liquid Polymorphism and Double Criticality in a Lattice Gas Model

We analyze the possible phase diagrams of a simple model for an associating liquid proposed previously. Our two-dimensional lattice model combines oreintati onal ice-like interactions and \"{}Van der Waals\"{} interactions which may be repulsive, and in this case represent a penalty for distortion of hydrogen bonds in the presence of extra molecules. These interactions can be interpreted in terms of two competing distances, but not necessarily soft-core. We present mean -field calculations and an exhaustive simulation study for different parameters which represent relative strength of the bonding interaction to the energy penalty for its distortion. As this ratio decreases, a smooth disappearance of the doubl e criticality occurs. Possible connections to liquid-liquid transitions of molecul ar liquids are suggested

Seguro de salud y cobertura de vacunación en población infantil con y sin experiencia de desplazamiento forzado en colombia

Objetivo Determinar la cobertura de vacunación y su relación con el status de afiliación al seguro en niños y niñas menores de cinco años de edad, en condiciones de alta vulnerabilidad social.Material y métodos Estudio transversal en 514 familias residentes en asentamientos urbanos, receptores de población desplazada por conflicto armado, de 4 municipios del departamento de Santander, Colombia. A través de un muestreo probabilístico con afijación proporcional por municipio se seleccionaron los hogares y se aplicó una encuesta. Los datos de inmunización fueron obtenidos del carné de vacunación. La variable dependiente fue estar vacunado con esquema completo para la edad según los biológicos estipulados por el programa oficial del Ministerio de Protección Social. Mediante regresión logística se modeló la probabilidad de estar vacunado ajustando por las variables sociodemográficas.Resultados Se estudiaron 369 niños y niñas, de los cuales 48,8 % pertenecía a familias desplazadas por conflicto armado; 46,1 % de los entrevistados presentaroncarné de vacunación. Entre los que tenían carné, contrario a lo esperado, sólo 21,2 % estaba asegurado y 22,9 % estaba vacunado con esquema completo para la edad. La probabilidad de estar vacunado para la edad, dado que se está afiliado al sistema de salud mediante el régimen subsidiado, es 2,4 veces más, comparada con los no asegurados (p=0.042).Conclusión Las bajas coberturas de vacunación indican la existencia de barreras de acceso a los servicios y las bajas coberturas de afiliación al seguro sugieren fallas en las políticas de afiliación al seguro para poblaciones que viven en contextos de pobreza y desplazamiento

Experimental characterization of a microfluidic device based on passive crossflow filters for blood fractionation

The separation of red blood cells (RBCs) from blood plasma and the analysis of individual RBCs are of great importance, as they provide valuable information regarding the health of their donor. Recent developments in microfluidics and microfabrication have contributed to the fabrication of microsystems with complex features to promote the separation and analysis of RBCs. In this work, the separation capacity of a multi-step crossflow microfluidic device was evaluated by using a blood analogue fluid made by Brij L4 micelles and human RBCs separated from whole blood, suspended in a solution with hematocrits (Ht) of 0.5 and 1%. All the samples collected at the outlets of the device were experimentally analyzed and compared. The absorbance spectrum was also measured for the prepared blood samples. The results indicate that the tested blood analogue fluid has exhibited a flow behavior similar to that of blood. In addition, the optical absorbance spectrophotometry revealed that it was possible to evaluate the separation efficiency of the microfluidic device, concluding that the concentration of cells was lower at the most lateral outside outlets of the microchannel due to the cumulative effect of the multiple cross-flow filters

Caminhos para o empreendedorismo social

A experiência adquirida pela Fundação Aperam Acesita no trabalho de assessoramento, acompanhamento e co-financiamento de programas e projetos junto às organizações possibilitou-nos fazer uma análise bastante realista e crítica em relação a situação das mesmas, constatando que grande parte destas organizações possui uma carência no conhecimento necessário para buscar sua autonomia, auto-gestão e fortalecimento institucional. Da mesma forma suas capacidades coletivas raramente são exploradas e aproveitadas e poucas são as informações para acessar sua legalização, financiamentos/convênios, registros e certificados.Entendendo a importância de reunir um conjunto de informações para o desenvolvimento destas organizações focadas em uma legislação atualizada, o presente instrumento tem por finalidade oferecer, de maneira prática e objetiva, às organizações e ao empreendedor social, caminhos para seu protagonismo. Vale ressaltar que grande parte das informações contidas neste material referese à legislação de âmbito nacional, porém para atender a uma demanda particular, algumas informações estão direcionadas às organizações de municípios que fazem parte da área de atuação da Aperam South America -- Vale do Aço e Vale do Jequitinhonha "Caminhos para o Empreendedorismo Social" é uma iniciativa da Aperam South America, através da Fundação Aperam Acesita, em parceria com o Instituto Papel Solidário, que buscam contribuir com o desenvolvimento sustentável das comunidades