Wetting on a spherical wall: influence of liquid-gas interfacial properties

We study the equilibrium of a liquid film on an attractive spherical substrate for an intermolecular interaction model exhibiting both fluid-fluid and fluid-wall long-range forces. We first reexamine the wetting properties of the model in the zero-curvature limit, i.e., for a planar wall, using an effective interfacial Hamiltonian approach in the framework of the well known sharp-kink approximation (SKA). We obtain very good agreement with a mean-field density functional theory (DFT), fully justifying the use of SKA in this limit. We then turn our attention to substrates of finite curvature and appropriately modify the so-called soft-interface approximation (SIA) originally formulated by Napi\'orkowski and Dietrich [Phys. Rev. B 34, 6469 (1986)] for critical wetting on a planar wall. A detailed asymptotic analysis of SIA confirms the SKA functional form for the film growth. However, it turns out that the agreement between SKA and our DFT is only qualitative. We then show that the quantitative discrepancy between the two is due to the overestimation of the liquid-gas surface tension within SKA. On the other hand, by relaxing the assumption of a sharp interface, with, e.g., a simple smoothing of the density profile there, markedly improves the predictive capability of the theory, making it quantitative and showing that the liquid-gas surface tension plays a crucial role when describing wetting on a curved substrate. In addition, we show that in contrast to SKA, SIA predicts the expected mean-field critical exponent of the liquid-gas surface tension

ALTERAÇÕES Craniofaciais e Tomográficas em Pessoas Atingidas pela Hanseníase Atendidas no Programa de Unidade Básica de Saúde e no Hospital Colônia Pedro Fontes, Cariacica (ES), Brasil

Introdução: Hanseníase é doença infectocontagiosa, causada pelo Mycobacterium leprae, e, mais recentemente descrito, Mycobacterium lepromatosis, de evolução lenta, que se manifesta principalmente por meio de sinais e sintomas dermatoneurológicos. Além de afetar a pele e os nervos periféricos, também pode comprometer os tecidos nasais, olhos, testículos e ossos. Deformidades esqueléticas faciais e de extremidades são marcadores históricos e parte do estigma dessa doença. Objetivo: Estudar as alterações craniofaciais da hanseníase. Métodos: Foi realizado um estudo série de casos, no qual foram avaliados 55 pacientes, 26 ex-hansenianos do Hospital Colônia Pedro Fontes e 29 hansenianos atendidos na Unidade Básica de Saúde de Jardim América, ambos em Cariacica (ES), no período de setembro de 2015 a dezembro de 2016. Os participantes foram submetidos a um questionário com dados epidemiológicos, avaliação otorrinolaringológica e, quando necessário, exame tomográfico. Verificou-se associação entre algumas variáveis com alterações nasais/faciais clínicas e radiológicas, como: sexo, idade, tempo de demora no diagnóstico da hanseníase, classificação da hanseníase, grupo de participantes, face hansênica. Resultados: Dos principais resultados encontrados, destacam-se: dez (18,2%) pacientes apresentaram características de face hansênica, nove (16,4%) apresentavam a projeção da ponta nasal menor que o normal, 12 (21,8%) não tinham sustentação da ponta nasal e nove (16,4%) não tinham sustentação do dorso nasal, sendo que a columela se apresentou diminuída em 14 (25,5%). Quanto aos achados tomográficos dos 38 pacientes avaliados, verificou-se que os ossos próprios nasais estavam alterados em nove (23,6%), havia reabsorção da espinha nasal anterior (parcial ou total) em 21 (55,2%) e perfuração septal em cinco (13,2%), sendo que 16 (42,1%) apresentaram atrofia de cornetos inferior e médio. Além disso, entre os dentados superiores (com três ou mais incisivos superiores), apenas um (2,6%) apresentava reabsorção parcial com exposição radicular do processo alveolar da maxila, enquanto entre os desdentados 27 (71%) apresentavam reabsorção (parcial ou até processo palatino), 28 (73,7%) haviam perdido todos os quatro incisivos superiores. Conclusões: Alterações ósseas e na espinha nasal anterior e processo alveolar da maxila foram frequentes. Entretanto, alterações dos ossos próprios nasais foram observadas apenas nos vichowianos. O tempo médio do aparecimento da primeira lesão até o diagnóstico da doença foi de 28,69 meses, o que sugere o diagnóstico ainda tardio da hanseníase. A perfilometria mostrou alterações. Porém, não há estudos sobre este assunto em hansenianos que permita comparações. Alterações nasais estavam presentes em 5,5% a 36,4% dos pacientes. As alterações tomográficas variaram de 9% a 70%, dependendo da estrutura, sendo mais prevalentes nos virchowianos e em pacientes com mais de dez anos de diagnóstico da doença. Quadros avançados clinicamente foram evidenciados no exame de imagem. O exame radiológico contribuiu e confirmou os achados otorrinolaringológicos, evidenciando a importância dos dois exames nos pacientes com hanseníase ou ex-portadores da doença

On the genesis of spike-wave activity in a mean-field model of human brain activity

In this letter, the genesis of spike-wave activity - a hallmark of many generalized epileptic seizures - is investigated in a reduced mean-field model of human neural activity. Drawing upon brain modeling and dynamical systems theory, we demonstrate that the thalamic circuitry of the system is crucial for the generation of these abnormal rhythms, observing that the combination of inhibition from reticular nuclei and excitation from the external signal, interplay to generate the spike-wave oscillation. We demonstarte that this is a nonlinear phenomena and that linear stability analysis is not appropriate to explain such solutions

Second generation bioethanol production: on the use of pulp and paper industry wastes as feedstock

Due to the health and environment impacts of fossil fuels utilization, biofuels have been investigated as a potential alternative renewable source of energy. Bioethanol is currently the most produced biofuel, mainly of first generation, resulting in food-fuel competition. Second generation bioethanol is produced from lignocellulosic biomass, but a costly and difficult pretreatment is required. The pulp and paper industry has the biggest income of biomass for non-food-chain production, and, simultaneously generates a high amount of residues. According to the circular economy model, these residues, rich in monosaccharides, or even in polysaccharides besides lignin, can be utilized as a proper feedstock for second generation bioethanol production. Biorefineries can be integrated in the existing pulp and paper industrial plants by exploiting the high level of technology and also the infrastructures and logistics that are required to fractionate and handle woody biomass. This would contribute to the diversification of products and the increase of profitability of pulp and paper industry with additional environmental benefits. This work reviews the literature supporting the feasibility of producing ethanol from Kraft pulp, spent sulfite liquor, and pulp and paper sludge, presenting and discussing the practical attempt of biorefineries implementation in pulp and paper mills for bioethanol production.publishe

Fluid structure in the immediate vicinity of an equilibrium three-phase contact line and assessment of disjoining pressure models using density functional theory

We examine the nanoscale behavior of an equilibrium three-phase contact line in the presence of long-ranged intermolecular forces by employing a statistical mechanics of fluids approach, namely density functional theory (DFT) together with fundamental measure theory (FMT). This enables us to evaluate the predictive quality of effective Hamiltonian models in the vicinity of the contact line. In particular, we compare the results for mean field effective Hamiltonians with disjoining pressures defined through (I) the adsorption isotherm for a planar liquid film, and (II) the normal force balance at the contact line. We find that the height profile obtained using (I) shows good agreement with the adsorption film thickness of the DFT-FMT equilibrium density profile in terms of maximal curvature and the behavior at large film heights. In contrast, we observe that while the height profile obtained by using (II) satisfies basic sum rules, it shows little agreement with the adsorption film thickness of the DFT results. The results are verified for contact angles of 20, 40 and 60 degrees

Two-stage aeration fermentation strategy to improve bioethanol production by scheffersomyces stipitis

Hardwood spent sulfite liquor (HSSL) is a by-product from pulp industry with a high concentration of pentose sugars, besides some hexoses suitable for bioethanol production by Scheffersomyces stipitis. The establishment of optimal aeration process conditions that results in specific microaerophilic conditions required by S. stipitis is the main challenge for ethanol production. The present study aimed to improve the ethanol production from HSSL by S. stipitis through a two-stage aeration fermentation. Experiments with controlled dissolved oxygen tension (DOT) in the first stage and oxygen restriction in the second stage were carried out. The best results were obtained with DOT control at 50% in the first stage, where the increase of oxygen availability provided faster growth and higher biomass yield, and no oxygen supply with an agitation rate of 250 rpm, in the second stage allowed a successful induction of ethanol production. Fermentation using 60% of HSSL (v/v) as substrate for S. stipitis provided a maximum specific growth rate of 0.07 h−1 , an ethanol productivity of 0.04 g L h−1 and an ethanol yield of 0.39 g g−1 , respectively. This work showed a successful two-stage aeration strategy as a promising aeration alternative for bioethanol production from HSSL by S. stipitis.publishe

Selection of high performance strains of edible mycorrhizal fungi for improved abiotic stress resistance

info:eu-repo/semantics/publishedVersio