156 resultados para physicochemical formulation


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A hidrólise enzimática do amido pode fornecer informações importantes sobre sua estrutura granular. Amidos de mandioca, batata-doce, mandioquinha-salsa e batata foram hidrolisados por α-amilase bacteriana a 37 °C durante 48 horas, e algumas propriedades físico-químicas dos resíduos da hidrólise foram determinadas. O amido de mandioca foi o mais suscetível à enzima com 20,9% de hidrólise, enquanto o amido de batata foi o mais resistente com 5,9%. O tamanho médio dos grânulos variou de 10,8 a 23,4 μm para os amidos de mandioquinha-salsa e batata, respectivamente. Amidos de mandioca e batata-doce apresentaram um padrão de difração de raio-X tipo A, enquanto os amidos de mandioquinha-salsa e batata mostraram padrão tipo B. Todos os amidos nativos mostraram superfície granular lisa e, após hidrólise, os amidos de mandioca, batata-doce e mandioquinha-salsa mostraram alguns grânulos bastante degradados, enquanto o amido de batata apresentou sutil sinal de degradação. O teor de amilose dos amidos diminuiu com a hidrólise para os amidos de mandioca, batata-doce e mandioquinha-salsa, permanecendo inalterado para o amido de batata. Como esperado, a viscosidade intrínseca e as propriedades de pasta diminuíram para todos os amidos hidrolisados. Não houve diferença significativa entre as propriedades térmicas dos amidos nativos e hidrolisados. Estes resultados sugeriram que a hidrólise ocorreu nas áreas cristalinas e amorfas dos grânulos. O padrão de difração do tipo B e o grande tamanho dos grânulos do amido de batata podem ter contribuído para a maior resistência deste amido à hidrólise.

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In this Letter, an entropy operator for the general unitary SU(1, 1) TFD formulation is proposed and used to lead a bosonic system from zero to finite temperature. Namely, considering the closed bosonic string as the target system, the entropy operator is used to construct the thermal vacuum. The behaviour of such a state under the breve conjugation rules is analyzed and it was shown that the breve conjugation does not affect the thermal effects. From this thermal vacuum the thermal energy, the entropy and the free energy of the closed bosonic string are calculated and the appropriated thermal distribution for the system is found after the free energy minimization. (C) 2004 Elsevier B.V. All rights reserved.

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A non-integrable phase-factor global approach to gravitation is developed by using the similarity of teleparallel gravity to electromagnetism. The phase shifts of both the COW and the gravitational Aharonov-Bohm effects are obtained. It is then shown, by considering a simple slit experiment, that in the classical limit the global approach yields the same result as the gravitational Lorentz force equation of teleparallel gravity. It represents, therefore, the quantum mechanical version of the classical description provided by the gravitational Lorentz force equation. As teleparallel gravity can be formulated independently of the equivalence principle, it will consequently require no generalization of this principle at the quantum level.

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In this Letter we discuss a generalization for the thermal Bogoliubov transformation in the context of a Hermitian general SU(1,1) transformation generator. The TFD tilde conjugation rules are redefined using an appropriated Tomita-Takesaki modular operator. (C) 2003 Elsevier B.V. All rights reserved.

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A quaternionic version of Quantum Mechanics is constructed using the Schwinger's formulation based on measurements and a Variational Principle. Commutation relations and evolution equations are provided, and the results are compared with other formulations.

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This work is an application of the second order gauge theory for the Lorentz group, where a description of the gravitational interaction is obtained that includes derivatives of the curvature. We analyze the form of the second field strength, G=partial derivative F+fAF, in terms of geometrical variables. All possible independent Lagrangians constructed with quadratic contractions of F and quadratic contractions of G are analyzed. The equations of motion for a particular Lagrangian, which is analogous to Podolsky's term of his generalized electrodynamics, are calculated. The static isotropic solution in the linear approximation was found, exhibiting the regular Newtonian behavior at short distances as well as a meso-large distance modification.

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We have studied the null plane hamiltonian structure of the free Yang Mills fields. Following the Dirac's procedure for constrained systems we have performed a detailed analysis of the constraint structure of the model and we give the generalized Dirac brackets for the physical variables. Using the correspondence principle in the Dime's brackets we obtain the same commutators present in the literature and new ones.

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A novel strategy to handle divergences typical of perturbative calculations is implemented for the Nambu-Jona-Lasinio model and its phenomenological consequences investigated. The central idea of the method is to avoid the critical step involved in the regularization process, namely, the explicit evaluation of divergent integrals. This goal is achieved by assuming a regularization distribution in an implicit way and making use, in intermediary steps, only of very general properties of such regularization. The finite parts are separated from the divergent ones and integrated free from effects of the regularization. The divergent parts are organized in terms of standard objects, which are independent of the ( arbitrary) momenta running in internal lines of loop graphs. Through the analysis of symmetry relations, a set of properties for the divergent objects are identified, which we denominate consistency relations, reducing the number of divergent objects to only a few. The calculational strategy eliminates unphysical dependencies of the arbitrary choices for the routing of internal momenta, leading to ambiguity-free, and symmetry-preserving physical amplitudes. We show that the imposition of scale properties for the basic divergent objects leads to a critical condition for the constituent quark mass such that the remaining arbitrariness is removed. The model becomes predictive in the sense that its phenomenological consequences do not depend on possible choices made in intermediary steps. Numerical results are obtained for physical quantities at the one-loop level for the pion and sigma masses and pion-quark and sigma-quark coupling constants.

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Estudou-se o reuso de água de um sistema composto por estação de tratamento de esgoto (ETE) com aeração prolongada e lodo ativado, e em uma estação compacta de tratamento de água (ECTA) de uma indústria metalúrgica. Os processos para obtenção da água de reuso foram: microbiológico e físico-químico. O esgoto doméstico foi bombeado para a ETE, onde houve formação de flocos biológicos e água clarificada. Avaliou-se a eficiência do processo microbiológico da ETE mediante a remoção de demanda bioquímica de oxigênio (DBO), demanda química de oxigênio (DQO) e sólidos sedimentáveis (SS). A eficiência do processo físico-químico de clarificação e desinfecção foi avaliada mediante análises de pH, turbidez, cor, contagem de bactérias heterotróficas aeróbias, cloro livre, dureza, alcalinidade, cloretos, sulfatos, sólidos totais dissolvidos (STD). Na água de reuso além desses parâmetros avaliou-se a toxicidade aguda ao microcrustáceo Daphnia similis.