Batch distillation: Better at constant or variable reflux?

Due to its outstanding flexibility, batch distillation is still widely used in many separation processes. In the present work, a comparison between constant and variable reflux operations is studied. Firstly, a mathematical model is developed and then validated through comparison between predicted and experimental results accomplished in a lab-scale apparatus. Therefore, case studies are performed through mathematical simulations. It is noted that the most economical form of batch distillation is at constant overhead product composition, keeping the flow rate of vapor from the top of the column constant. (C) 2010 Elsevier B.V. All rights reserved.

Liquid-Liquid Equilibrium of Aqueous Two-Phase Systems Containing Some Synthetic Polyelectrolytes and Polyethylene Glycol

Experimental results are presented for the liquid-liquid equilibrium of aqueous two-phase systems containing a synthetic polyelectrolyte (polysodium acrylate, polysodium methacrylate, and polysodium ethylene sulfonate) and polyethylene glycol at (298.2 and 323.2) K. A total of 40 phase diagrams were obtained, comprising data both of the binodal curve (obtained through cloud-point measurements) and of equilibrium compositions. The influences of temperature, the nature of the polyelectrolyte monomer unit, and the chain length of both types of polymers are analyzed and discussed.

Photo-Fenton removal of water-soluble polymers

This paper presents the results of experiments carried out in a laboratory-scale photochemical reactor on the photodegradation of different polymers in aqueous solutions by the photo-Fenton process. Solutions of three polymers, polyethyleneglicol (PEG), polyacrylamide (PAM), and polyvinylpyrrolidone(PVP), were tested under different. conditions. The reaction progress was evaluated by sampling and analyzing the total organic carbon concentration in solution (TOC) along the reaction time. The behavior of the different polymers is discussed, based oil the evolution of the TOC-time curves. Under specific reaction conditions, the formation and coalescence of solid particles was Visually observed. Solids formation occurred simultaneously to a sharp decrease in the TOC of the liquid phase. This may be favorable for the treatment of industrial wastewater containing polymers, since the photodegradation process can be Coupled with solid separation systems. which may reduce the treatment cost. (C) 2008 Elsevier B.V. All rights reserved.

Thermodynamics of aqueous solutions of polyelectrolytes: Experimental results for the activity of water in aqueous solutions of (a single synthetic polyelectrolyte and sodium chloride)

Experimental results for the activity of water in aqueous solutions of 10 single, synthetic polyelectrolytes (polysodium acrylate, polysodium methacrylate, polyammonium acrylate, polysodium ethylene sulfonate, and polysodium styrene sulfonate) and sodium chloride at 298.2 K are presented. The experimental work was performed by applying the isopiestic method with sodium chloride as a reference substance. As expected, the activity of water decreases when the concentration of a polyelectrolyte and/or sodium chloride increases. At constant concentration of a polyelectrolyte and sodium chloride, the activity of water depends on the monomer unit and the molecular mass of the polyelectrolyte. The new data are to be used in future work to develop and test models for the Gibbs excess energy of aqueous solutions of polyelectrolytes.

Thermodynamics of aqueous solutions of polyelectrolytes: Experimental results for the activity of water in aqueous solutions of some single synthetic polyelectrolytes

Experimental results for the activity of water in aqueous solutions of 10 single polyelectrolytes (two polysodium acrylates, two polysodium methacrylates, three polyammonium acrylates, two polysodium ethylene sulfonates, and one polysodium styrene sulfonate) at (298.2 and 323.2) K are reported. The isopiestic method was employed in these experiments with aqueous solutions of sodium chloride as references. The polyelectrolytes were characterized by three averaged molecular masses determined by gel permeation chromatography. Furthermore, the density and the refractive index increments of the aqueous polyelectrolyte solutions are reported. Although a similar pattern for the activity of water was observed for all systems (i.e., the osmotic coefficient increases with rising polyelectrolyte concentration), the experimental results show that this property depends on the monomer type as well as on the size of the polymer chain. The temperature (varied from (298.2 to 323.2) K) has only a small influence on the activity of water.

Phase equilibria for salt-induced lysozyme precipitation: Effect of salt concentration and pH

The salt-induced precipitation of lysozyme from aqueous solutions was studied at 25 degrees C and various pH values by cloud-point investigations, precipitation experiments (analysing the compositions of the coexisting phases) and microscopic investigations of the precipitates. Sodium sulphate as well as ammonium sulphate were used to induce the precipitation. The experimental results are discussed and used to develop a scheme of the phase equilibrium in water-rich aqueous solutions of lysozyme and either Na2SO4 or (NH4)(2)SO4. (C) 2007 Elsevier B.V All rights reserved.

Continuous extraction of alpha-toxin from a fermented broth of Clostridium perfringens Type A in perforated rotating disc contactor using aqueous two-phase PEG-phosphate system

A 2(3-1) factorial experimental design was used to evaluate the performance of a perforated rotating disc contactor to extract alpha-toxin from the fermented broth of Clostridium perfringens Type A by aqueous two-phase system of polyethylene glycol-phosphate salts. The influence of three independent variables, specifically the dispersed phase flowrate, the continuous phase flowrate and the disc rotational speed, was investigated on the hold up, the mass transfer coefficient, the separation efficiency and the purification factor, taken as the response variables. The optimum dispersed phase flowrate was 3.0 mL/min for all these responses. Besides, maximum values of hold up (0.80), separation efficiency (0. 10) and purification factor (2.4) were obtained at this flowrate using the lowest disc rotational speed (35 rpm), while the optimum mass transfer coefficient (0. 165 h(-1)) was achieved at the highest agitation level (140 rpm). The results of this study demonstrated that the dispersed phase flowrate strongly influenced the performance of PRDC, in that both the mass transfer coefficient and hold up increased with this parameter. (c) 2007 Elsevier B. V. All rights reserved.

Liquid-liquid extraction of proteases from fermented broth by PEG/citrate aqueous two-phase system

This work deals with the use of an aqueous two-phase system (ATPS) of PEG/citrate to remove proteases from a Clostridium perfringens fermentation broth. To plan the experimental tests and evaluate the corresponding results, three successive experimental designs were employed, for which the PEG molar mass (M-PEG) and concentration (C-PEG), the citrate concentration (C-C) and the pH were selected as independent variables, while the purification factor (PF), the partition coefficient (K), the activity yield (Y) and the selectivity (S) were selected as responses. PF of proteases in the top phase was shown to increase with increasing MPEG and decreasing Cc, whereas a completely opposite trend was observed for K. On the other hand, Y was favored by simultaneous decreases in both these variables, while S decreased with increasing Cc. Therefore, selecting a simultaneous increase in PF and Y as the most desirable result, the best performance of the system was obtained using M-PEG = 10-000 g/mol C-PEG = 22% (w/w) and C-c = 8.0% (w/w) at pH 8.5. Under these conditions, the activity yield was very high (131 %) but the purification factor (4.2) and the selectivity (4.3) were lower than those ensured by more selective purification methods. According to these results, the ATPS seems to be an interesting alternative primary concentration/decontamination step for vaccine preparation from C. perfringens fermented broth. (C) 2007 Elsevier B.V. All rights reserved.

Effect of process variables on fluiddynamics and adhesion efficiency during spouted bed coating of hard gelatine capsules

This article presents an evaluation of the effects of the spouted bed design and operating conditions on system fluiddynamics and process performance during enteric coating of hard gelatine capsules. The design parameters studied were the column diameter (150 mm and 200 mm), the included angle of the conical base, gamma (60 degrees or 40 degrees) and the presence or absence of a Venturi inserted before the inlet air orifice. The process variables studied were the ratio between the feed flow rate of the coating suspension to the spouting gas flow rate (W(s)/W(g)), the mass of capsules loaded to the equipment (M(0)), and the ratio between the Spouting gas flow rate to the gas flow rate at minimum spouting condition (Q/Q(ms)). The response variables were the rate of increase of the capsules mass (K(1)), and the adhesion efficiency (eta). The linear regression equation for the dependent variable K, in terms of the independent variables adequately described the process with an r(2) value of 0.872. Analysis of variance (ANOVA) revealed that increasing of W(s)/W(g), Q/Q(ms) and gamma significantly increased the adhesion efficiency. Adhesion efficiencies higher than 90% were achieved by selecting precise coating conditions, indicating the feasibility of the process for coating of hard gelatine capsules. (C) 2008 Elsevier B.V. All rights reserved.

Subcortical brain mechanisms in speech and language

This paper reviews current research and contemporary theories of subcortical participation in the motor control of speech production and language processing. As a necessary precursor to the discussion of the functional roles of the basal ganglia and thalamus, the neuroanatomy of the basal ganglial-thalamocortical circuitry is described. Contemporary models of hypokinetic and hyperkinetic movement disorders based on recent neuroanatomical descriptions of the multi-segmented circuits that characterise basal ganglion anatomy are described. Reported effects of surgically induced lesions in the globus pallidus and thalamus on speech production are reviewed. In addition, contemporary models proposed to explain the possible contribution of various subcortical structures to language processing are described and discussed in the context of evidence gained from observation of the effects of circumscribed surgically induced lesions in the basal ganglia and thalamus on language function. The potential of studies based on examination of the speech/language outcomes of patients undergoing pallidotomy and thalamotomy to further inform the debate relating to the role of subcortical structures in speech motor control and language processing is highlighted. Copyright (C) 2001 S. Karger AG, Basel.

Formação, educação física e inclusão : compreendendo os processos inclusivos

No intuito de contribuir para a problematização da Educação, numa perspectiva inclusiva, esta dissertação procura conhecer e analisar a prática pedagógica inclusiva experimentada pelos professores de Educação Física na escola, por meio de suas narrativas, em uma ação de formação continuada. O projeto de extensão intitulado Formação Continuada de Professores de Educação Física para a Educação Inclusiva foi a estratégia utilizada para a criação de um grupo de estudos, denominado Grupo Operativo de Formação (GOF). A ação de formação continuada foi realizada durante o período de julho a dezembro de 2011, em um encontro presencial semanal, totalizando dezesseis encontros, com uma carga horária final de 90h. Participaram da ação de formação quatro professores da Secretaria Municipal de Educação de Vitória-ES. A pesquisa baseia-se em elementos da pesquisa-ação, utilizando como instrumentos e procedimentos para a produção dos dados a narrativa, o diário de campo, o memorial e a entrevista. Da análise dos dados produzidos identifica três categorias norteadoras das discussões: a) o trabalho coletivo como possibilidade para inclusão; b) trilhando caminhos para o desenvolvimento de práticas inclusivas: o autismo como foco do percurso; c) o olhar dos professores sobre a ação de formação experimentada no GOF. As análises realizadas revelam que essa ação de formação traz resultados que sinalizam positivamente para sua efetivação como instrumento ativo no processo de formação de professores para a educação básica, na perspectiva da inclusão. Portanto, essa é uma interessante ferramenta a ser utilizada pelas redes de ensino como alternativa metodológica em programas de formação continuada. Além disso, a proposta promove momentos para a prática reflexiva dos professores, representando uma rica oportunidade, capaz de fazer com que eles se apropriem de teorias educacionais que poderão contribuir na elaboração de suas aulas.

Práticas docentes de leitura e escrita no quarto e quinto anos do Ensino Fundamental, em escolas públicas do município de Vitória (ES)

A presente pesquisa, desenvolvida na linha Cultura, Currículo e Formação de Educadores, pelo Programa de Pós-Graduação da Universidade Federal do Espírito Santo, tem como objetivo investigar práticas docentes consideradas pelas professoras do 4º e 5º anos do EF como promotoras de leitura e escrita em escolas do Sistema Municipal de Educação Vitória(ES). Apoiamo-nos, para isso, na base teórica da perspectiva histórico-cultural a partir de Bakhtin (2003, 2010); Freitas (2007, 2012) e Fichtner (2012). Levamos em consideração os conceitos de sujeito, linguagem e texto desenvolvidos por Bakhtin (2003, 2010); de educação e dialogicidade em Freire (1967, 1987, 1997, 2010); e de parceria em Foerste (2005); dentre outros, no sentido de buscar respostas para as perguntas: que práticas docentes estão sendo consideradas pelas professoras desses dois anos de escolarização como promotoras de leitura e escrita? Que políticas têm promovido tais práticas? Quem são os beneficiados/prejudicados por tais formas de ensinar? A pesquisa se deu por meio de um estudo de caso realizado durante o ano letivo de 2013 com docentes que atuam junto às turmas em questão, em duas escolas do EF. Utilizamos como procedimentos para a produção de dados a observação participante, o questionário, a entrevista, o acompanhamento de atividades desenvolvidas nos cadernos de alunos e a análise documental. A análise dos dados foi organizada a partir das categorias sujeito, linguagem e texto. Os resultados evidenciam que, conforme a concepção bakhtiniana de linguagem e a freireana de educação, as práticas docentes observadas ainda não sinalizam a promoção da leitura e da escrita junto aos alunos do 4º e 5º anos EF, sendo necessário para isso que se repensem as políticas públicas, em especial as voltadas para a formação de professores, com o intuito de beneficiar os estudantes oferecendo-lhes uma formação que lhes permita ter a consciência de que o centro de gravidade da linguagem não reside nas normas, mas na significação que essa forma adquire no contexto, na interação com outros sujeitos.