2,870 research outputs found
Wetting phenomenon in the liquid-vapor phase coexistence of a partially miscible Lennard-Jones binary mixture
We have carried out extensive equilibrium molecular dynamics (MD) simulations
to study the structure and the interfacial properties in the liquid-vapor (LV)
phase coexistence of partially miscible binary Lennard-Jones (LJ) mixtures. By
analyzing the structural properties as a function of the miscibility parameter,
, we found that at relatively low temperatures the system separates
forming a liquid A-liquid B interface in coexistence with the vapor phase. At
higher temperatures and, , we found a temperature range,
, where the liquid phases
are wet by the vapor phase. Here, represents the wetting
transition temperature (WTT) and is the consolute
temperature of the mixture. However, for , no wetting
phenomenon occurs. For the particular value, , we analyzed
quantitatively the versus , and versus
phase diagrams and found, , and
. We also studied quantitatively, as a function of
temperature, the surface tension and the adsorption of molecules at the
liquid-liquid interface. It was found that the adsorption shows a jump from a
finite negative value up to minus infinity, when the vapor wets the liquid
phases, suggesting that the wetting transition (WT) is of first order. The
calculated phase diagram together with the wetting phenomenon strongly suggest
the existence of a tricritical point. These results agree well with some
experiments carried out in fluid binary mixtures.Comment: Enlarged version that include results of more extensive simulations.
A total of 24 LaTeX pages that include 12 encapsulated poscript figures. To
appear in PRE, Vol. 70, issue Sept. 1st (2004
A density functional theory insight towards the rational design of ionic liquids for SO2 capture
A systematic density functional theory (DFT) analysis has been carried out to obtain information at the molecular level on the key parameters related to efficient SO2 capture by ionic liquids (ILs). A set of 55 ILs, for which high gas solubility is expected, has been selected. SO2 solubility of ILs was firstly predicted based on the COSMO-RS (Conductor-like Screening Model for Real Solvents) method, which provides a good prediction of gas solubility data in ILs without prior experimental knowledge of the compounds' features. Then, interactions between SO2 and ILs were deeply analyzed through DFT simulations. This work provides valuable information about required factors at the molecular level to provide high SO2 solubility in ILs, which is crucial for further implementation of these materials in the future. In our opinion, systematic research on ILs for SO2 capture increases our knowledge about those factors which could be controlled at the molecular level, providing an approach for the rational design of task-specific ILs.Ministerio de Economı´a y Competitividad
(Spain, project CTQ2013-40476-R) and Junta de Castilla y León
(Spain, project BU324U14
Female Hematozoan Infection Reduces Hatching Success but not Fledging Success in Pied Flycatchers Ficedula hypoleuca
Understanding agroforestry practices in Europe through landscape features policy promotion
Agroforestry understood as the combination of a woody component (forest tree, shrub, fruit tree) with an agricultural use of the understory is not clearly identified as such by the European Common Agricultural Policy (CAP). Despite the protection and promotion of the woody component in different parts of the CAP political text, the identification of agroforestry is not clear, although it can be recognised in the description of some landscape features, such as isolated trees and different types of hedgerows. Moreover, it is important to identify the extent of such woody components promoted by the CAP in agricultural lands to validate the impact of current and future measures. This paper aims at the characterisation of the current extent of landscape features all over Europe by analysing the Rural Development Program (RDP) measures within the CAP 2007–2013 and 2014–2020 that promote said features in Europe to increase the ecosystem service delivery. Isolated trees and hedgerows are protected unsatisfactorily through the Cross-compliance and Greening of CAP Pillar I. In contrast, Agri-environment measures associated to Pillar II are used in most European countries to protect both isolated trees and hedgerows and to promote them as boundary elements. The promotion of hedgerows and isolated trees mainly related to silvoarable and silvopastoral agroforestry practices is aimed at the promotion of the ecosystem services (such as water protection and biodiversity) and improvement in resilience (such as adaptation to climate change) they provide; therefore, the agroforestry environment benefits are indeed recognised. Landscape features comprising woody perennials should be associated with agroforestry when present in arable and permanent grasslands
Costos y desempeño económico del traslado en el tiempo de productos agrícolas: el silobolsa en Argentina
El silobolsa en Argentina es una herramienta consolidada de traslado en el tiempo de la producción granaria, ampliamente utilizada por productores agropecuarios, acopios, industrias y otros actores de los complejos agroalimentarios. Más allá de su desempeño positivo en aspectos como el poder de negociación, la estacionalidad de la producción, la infraestructura de almacenaje, el trasporte y la exportación, entre otros, es necesario analizar el desempeño económico-financiero en los niveles micro (organizaciones). El presente trabajo analiza las diferencias entre los sobreprecios obtenidos en los meses de mayor estacionalidad y los costos erogables y no erogables asociados a la estrategia de traslado en el tiempo de la producción por medio de silobolsa en los cultivos de trigo, soja, girasol y maíz en el período 2004-2014. En la mayoría de los años bajo estudio los desempeños económicos vinculados a la estrategia fueron negativos, en soja el 95% de los años arrojó diferenciales negativos, en girasol el 77%, en trigo el 62% y en maíz el 78%.The silobag in Argentina is an agricultural production commercial tool widely used by farmers, stockpiles, industry and other stakeholders in the agri-food complex. Beyond its positive performance in areas such as bargaining power, the seasonality of production, infrastructure, storage, transportation and export, among others, is necessary to analyze the economic and financial performance in the micro level (organizations). This paper analyzes the differences between the premiums obtained in the months of greater seasonality and the cash and non-cash costs associated with the transfer strategy in time production through the silobag in wheat, soybean, sunflower and corn in years 2004-2014. In most of the years study economic results were negative, in 95% of soybean years was negative differential, in sunflower 77%, 62% in wheat and 78% in corn.Gerencia de Comunicación e Imagen InstitucionalFil: Ferro Moreno, Santiago. Universidad Nacional de La Pampa. Facultad de Agronomía. Licenciatura en Administración de Negocios Agropecuarios. Cátedra de Costos; ArgentinaFil: Paturlanne, J. Universidad Nacional de La Pampa. Facultad de Agronomía. Licenciatura en Administración de Negocios Agropecuarios. Cátedra de Costos; Argentin
FPGA implementation of embedded fuzzy controllers for robotic applications
Fuzzy-logic-based inference techniques provide efficient solutions for control problems in classical and emerging applications. However, the lack of specific design tools and systematic approaches for hardware implementation of complex fuzzy controllers limits the applicability of these techniques in modern microelectronics products. This paper discusses a design strategy that eases the implementation of embedded fuzzy controllers as systems on programmable chips. The development of the controllers is carried out by means of a reconfigurable platform based on field-programmable gate arrays. This platform combines specific hardware to implement fuzzy inference modules with a general-purpose processor, thus allowing the realization of hybrid hardware/soffivare solutions. As happens to the components of the processing system, the specific fuzzy elements are conceived as configurable intellectual property modules in order to accelerate the controller design cycle. The design methodology and tool chain presented in this paper have been applied to the realization of a control system for solving the navigation tasks of an autonomous vehicle
Analysis of Sport Supplement Consumption by Competitive Swimmers According to Sex and Competitive Level.
Sports supplements (SS) are commonly used by athletes to improve their performance. SS use by competitive swimmers is reported to be prevalent but there is no evidence of such use by elite swimmers, either male or female. The objective of this research was to study the patterns of SS use by competitive swimmers based on sex and competitive levels (national and international); Methods: Using the categories of the Australian Institute of Sport (AIS), a total of 102 competitive swimmers (59 men and 43 women) completed a validated self-administered questionnaire on the use of SS; (3) Results: Overall, 86.9% of swimmers had consumed SSs with no differences observed between males and females (p = 0.247) or between competitive levels (p = 0.597). The SS that were most consumed by swimmers were caffeine (53.5%), sport drinks (52.5%), sport bars (51.5%), and vitamin C (43.4%). SSs categorized as medical supplements were consumed significantly more frequently by international swimmers (p = 0.012), with significant differences also found in the level—sex interaction (p = 0.049); (4) Conclusions: Compared to other sports disciplines, the prevalence of SS consumption is high in competitive swimmers regardless of performance level or gender. However, the consumption of medical supplements was greater in swimmers at a higher performance level.pre-print1202 K
Cyclooxygenase-2 Expression in Bladder Cancer and Patient Prognosis: Results from a Large Clinical Cohort and Meta-Analysis
Aberrant overexpression of cyclooxygenase-2 (COX2) is observed in urothelial carcinoma of the bladder (UCB). Studies evaluating COX2 as a prognostic marker in UCB report contradictory results. We determined the prognostic potential of COX2 expression in UCB and quantitatively summarize the results with those of the literature through a meta-analysis. Newly diagnosed UCB patients recruited between 1998–2001 in 18 Spanish hospitals were prospectively included in the study and followed-up (median, 70.7 months). Diagnostic slides were reviewed and uniformly classified by expert pathologists. Clinical data was retrieved from hospital charts. Tissue microarrays containing non-muscle invasive (n = 557) and muscle invasive (n = 216) tumours were analyzed by immunohistochemistry using quantitative image analysis. Expression was evaluated in Cox regression models to assess the risk of recurrence, progression and disease-specific mortality. Meta-hazard ratios were estimated using our results and those from 11 additional evaluable studies. COX2 expression was observed in 38% (211/557) of non-muscle invasive and 63% (137/216) of muscle invasive tumors. Expression was associated with advanced pathological stage and grade (p<0.0001). In the univariable analyses, COX2 expression - as a categorical variable - was not associated with any of the outcomes analyzed. As a continuous variable, a weak association with recurrence in non-muscle invasive tumors was observed (p-value = 0.048). In the multivariable analyses, COX2 expression did not independently predict any of the considered outcomes. The meta-analysis confirmed these results. We did not find evidence that COX2 expression is an independent prognostic marker of recurrence, progression or survival in patients with UCB.The work was partially supported by the Fondo de Investigaciones Sanitarias, Instituto de Salud Carlos III, Ministry of Science and Innovation, Spain (G03/174, 00/0745, PI051436, PI061614 and G03/174); Red Temática de Investigación Cooperativa en Cáncer- RD06/0020-RTICC; Consolider ONCOBIO; EU-FP6-STREP-37739-DRoP-ToP; EU-FP7-HEALTH-F2-2008-201663-UROMOL; EU-FP7-HEALTH-F2-2008-201333-DECanBio; USA-NIH-RO1-CA089715; and a PhD fellowship awarded to MJC from the ‘‘la Caixa’’ foundation, Spain, and a postdoctoral fellowship awarded to AFSA from the Fundación Científica de la AEC
Estimation of kinetic parameters in a chromatographic separation model via Bayesian inference
A modelagem de processos de adsorção tem sido empregada com frequência nas indústrias químicas, petroquímicas e refinarias, por exemplo para separação e purificação de misturas em unidade de Leito Móvel Simulado (LMS). Na representação matemática do modelo, a determinação de parâmetros é um passo importante para o projeto de condições cromatográficas para a separação contínua, em processos do tipo LMS. Este trabalho tem por objetivo a análise de estimativa de parâmetros em processos de adsorção, usando um sistema cromatográfico com uma coluna, para a separação das substâncias Glicose e Frutose. Investiga-se o uso da abordagem Bayesiana, através de métodos de Monte Carlo via Cadeias de Markov (MCMC), assim como o uso da abordagem da máxima verossimilhança, utilizando duas técnicas estocásticas diferentes, o Algoritmo de Colisão de Partículas (PCA - Particle Collision Algorithm), e o Algoritmo de Otimização por Enxame de Partículas (PSO - Particle Swarm Optimization) para executar a tarefa de minimização da função objetivo. Diferentes casos são apresentados com o objetivo de analisar a significância estatística das estimativas obtidas para os parâmetros, fazendo-se uma comparação crítica entre a solução via inferência Bayesiana e via minimização da função objetivo com métodos estocásticos. Os resultados obtidos demonstram que o uso da abordagem Bayesiana fornece uma proposta vantajosa para a estimativa de parâmetros em transferência de massa, oferecendo resultados com maior riqueza de informação estatística.The modeling of adsorption processes appears quite frequently in the chemical industry, petrochemical plants and refineries, for example for separation and purification of mixtures in Simulated Moving Bed (SMB) units. In the mathematical formulation, the accurate determination of the model parameters is an important step for the design of chromatographic conditions for continuous separation in SMB processes. This work is aimed at the estimation of the model parameters in adsorption processes, using a chromatographic column for the separation of glucose and fructose. The Bayesian framework for inverse problems is investigated through the implementation of Markov Chain Monte Carlo methods (MCMC) and a critical comparison against the classical Maximum Likelihood approach, with the minimization of the objective function via two different stochastic techniques, namely the Particle Collision Algorithm (PCA), and the Particle Swarm Optimization (PSO) is performed. Different cases are presented in order to investigate the statistical significance of the estimates obtained, and perform comparisons between the solution via Bayesian inference and via the minimization of the objective function with the stochastic methods. The results demonstrate that the Bayesian approach employs less computational effort to achieve estimates with comparable statistical information.Peer Reviewe
Diffusion-flame flickering as a hydrodynamic global mode
The present study employs a linear global stability analysis to investigate buoyancy-induced flickering of axisymmetric laminar jet diffusion flames as a hydrodynamic global mode. The instability-driving interactions of the buoyancy force with the density differences induced by the chemical heat release are described in the infinitely fast reaction limit for unity Lewis numbers of the reactants. The analysis determines the critical conditions at the onset of the linear global instability as well as the Strouhal number of the associated oscillations in terms of the governing parameters of the problem. Marginal instability boundaries are delineated in the Froude number/Reynolds number plane for different fuel jet dilutions. The results of the global stability analysis are compared with direct numerical simulations of time-dependent axisymmetric jet flames and also with results of a local spatio-temporal stability analysis.Norbert Peters pointed out the need for the present analysis in his seminal paper with John Buckmaster published thirty years ago (Buckmaster & Peters 1986). It is with great sorrow that we received the news of his passing last year. This paper is devoted to his memory in gratitude for his many outstanding contributions to Combustion Science.
The constructive comments of one anonymous referee have led to substantial improvements of the paper and are gratefully acknowledged. This work was supported by the Spanish MCINN through project no. CSD2010-00010 and by the Spanish MINECO through project no. DPI2014-59292-C3-1-P
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