Non-adiabatic effects in F + CHD3 reactive scattering

Palma J, Manthe U. Non-adiabatic effects in F + CHD3 reactive scattering. JOURNAL OF CHEMICAL PHYSICS. 2017;146(21): 214117.The effect of non-adiabatic transitions on the F(P-2) + CHD3(nu(1)) -> DF + CHD2 and F(P-2) + CHD3(nu(1)) -> HF + CD3 reactions is investigated. The dynamics of the nuclei was simulated using trajectory surface hopping and a vibronically and spin-orbit coupled diabatic potential energy matrix. To facilitate the calculations, the fewest switching algorithm of Tully was adapted to the use of a complex diabatic potential energy matrix. For reactions of CHD3 with ground state fluorine atoms, F(P-2(3/2)), the ratio between the previously computed adiabatic cross sections and the non-adiabatic ones was found to range from 1.4 to 2.1. The actual ratio depends on the translational energy and the initial vibrational state of CHD3. The total reactivity of CHD3(nu(1) = 1) was found to be always larger than that of CHD3(nu(1) = 0) mainly because of the increase in the cross sections for the HF + CD3 channel. Thus, the inclusion of non-adiabatic transitions in the theoretical treatment cannot resolve the existing disagreement between theory and experiment. Cross sections for the reaction of CHD3 with spin-orbit excited fluorine atoms, F(P-2(1/2)), were found to be significantly smaller than the ones for reaction with F(P-2(3/2)). Published by AIP Publishing

Direct mixed-quantum/classical computations of k(T). An analysis of the use of different coordinate systems

We have obtained three mixed-quantum/classical schemes to directly calculate thermal rate constants through the evaluation of flux-flux correlation function. These schemes are appropriate to treat three-atom reactions, but could be easily extended to larger systems. One of the schemes uses normal mode coordinates, defined at the transition state. The others use hyperspherical coordinates. The proposed algorithms were applied to the H + H2 → H2 + H reaction, and their accuracy was tested by comparison with full-quantum results. In this article, we present the derivation of the three mixed-quantum/classical schemes, describe the details of their implementation, and discuss the quality of their results.Fil: Clavero, Esteban Dario. Universidad Nacional de Quilmes. Centro de Estudios e Investigación; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Palma, Juliana Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Centro de Estudios e Investigación; Argentin

A comparison between reduced dimensionality and mixed quantum/classical evaluations of k(T) using the flux-flux correlation function formalism

Rate constants for the planar H + HD → H2 + D reaction with J = 0 have been calculated employing reduced dimensionality, mixed quantum/classical and full quantum computations based on the flux-flux correlation function formalism. It has been found that reduced dimensionality and mixed quantum/classical calculations afford quite similar results. This suggests that, for direct reactions occurring in the gas phase, there is no advantage in using the more involved mixed quantum/classical approach. On the other hand, the comparison between approximate and accurate results indicates that both, reduced dimensionality and mixed quantum/classical approaches, work well at medium and high temperatures. As expected, they fail at very low temperatures where tunnelling prevails.Fil: Clavero, Esteban Dario. Universidad Nacional de Quilmes. Centro de Estudios e Investigación; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Palma, Juliana Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Centro de Estudios e Investigación; Argentin

Fundações estatais de direito privado: viabilidade jurídica do PLP n. 92/2007

O presente artigo tem por objeto a análise da viabilidade jurídica do Projeto de Lei Complementar n. 92/2007, que se destina a disciplinar as fundações estatais de direito privado. Para tanto, foram identificados os obstáculos jurídicos atinentes ao tema das fundações governamentais a partir do relato do processo legislativo do PLP n. 92/2007, quais sejam, imprecisão semântica do termo "fundação pública", indeterminação do regime jurídico de direito privado e dúvidas quanto à possibilidade de as fundações estatais conferirem eficiência à Administração Pública. Em seguida, cada aspecto foi analisado por meio de estudo doutrinário e normativo. Como resultado da pesquisa, constatou-se que o modelo de fundação estatal proposto pelo referido projeto ainda não é juridicamente viável na medida em que não conseguiu vencer a celeuma terminológica que, consequentemente, impede a identificação mais precisa do regime de direito privado. Quanto à eficiência, concluiu-se que a mera previsão do regime de direito privado não é suficiente para dotar a Administração Pública de flexibilidade de gestão e eficiência, fazendo-se necessária a adoção de instrumentos contratuais.This article intends to analyze the juridical viability of the Project of Complementary Law PLP N. 92/2007 that will regulate the private law state foundations. It was pointed the main obstacles relationated with the theme of state foundations were pointed PLP N. 92/200: the semantically indetermination of the expression "state foundation"; indetermination of the private law discipline and doubts about the possibility of the private law state foundations to give the required efficiency to Public Administration. After that, each point was analyzed by normative and doctrinaire studies. As result of this research, this article pointed that the proposed model of state foundation is not juridical viable, once the terminological issue has not already been transposed and, consequently, remains an imprecisely identification of the private law discipline. In relation to efficiency, the merely announce of the private law discipline in the text of law is not sufficient to provide a flexible and efficient management; contractual instruments are necessary to reach this aim

Molecular Dynamics Simulations of Substrate Release from Trypanosoma cruzi UDP-Galactopyranose Mutase

The enzyme UDP-galactopyranose mutase (UGM) represents a promising drug target for the treatment of infections with Trypanosoma cruzi. We have computed the Potential of Mean Force for the release of UDP-galactopyranose from UGM, using Umbrella Sampling simulations. The simulations revealed the conformational changes that both substrate and enzyme undergo during the process. It was determined that the galactopyranose portion of the substrate is highly mobile and that the opening/closing of the active site occurs in stages. Previously uncharacterized interactions with highly conserved residues were also identified. These findings provide new pieces of information that contribute to the rational design of drugs against T. cruzi.Fil: Cossio Pérez, Rodrigo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pierdominici Sottile, Gustavo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sobrado, Pablo. No especifíca;Fil: Palma, Juliana Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentin

Positively charged residues in the head domain of P2X4 receptors assist the binding of ATP

P2X receptors are a family of trimeric cationic channels located in the membrane of mammalian cells. They open in response to the binding of ATP. The differences between the closed and open structures have been described in detail for some members of the family. However, the order in which the conformational changes take place as ATP enters the binding cleft, and the residues involved in the intermediate stages, are still unknown. Here, we present the results of umbrella sampling simulations aimed to elucidate the sequence of conformational changes that occur during the reversible binding of ATP to the P2X4 receptor. The simulations also provided information about the interactions that develop in the course of the process. In particular, they revealed the existence of a metastable state which assists the binding. This state is stabilized by positively charged residues located in the head domain of the receptor. Based on these findings, we propose a novel mechanism for the capture of ATP by P2X4 receptors.Fil: Racigh, Vanesa Elizabeth. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ormazábal, Agustín. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Palma, Juliana Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Pierdominici Sottile, Gustavo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Efeito do ácido clorídrico gasoso no esmalte humano e bovino

Objetivo: Avaliar a ação do ácido clorídrico gasoso sobre o esmalte humano e bovino e comparar o padrão de desmineralização desses substratos expostos ao agente erosivo gasoso. Métodos: Oito espécimes de esmalte bovino e oito de esmalte humano foram obtidos (4 × 4 × 2 mm), metade da superfície foi protegida com resina composta e a outra metade exposta ao ácido clorídrico gasoso (gHCl), pH 2 a 37 °C, por 3 min, 8 vezes ao dia, durante 12 dias, e em intervalos os espécimes foram mantidos em saliva artificial. Os espécimes foram analisados quanto ao perfil de desgaste, rugosidade superficial e microdureza (antes e após a exposição ao ácido). Os dados foram analisados estatisticamente por ANOVA de uma via. Resultados: Os dados não mostraram diferença significativa entre o esmalte bovino e humano para todas as propriedades analisadas – microdureza (98,1 ± 5,2, 96,9 ± 4,8), perfil de desgaste (11,5 ± 2,8, 11,4 ± 3,6) e rugosidade (2,6 ± 0,3, 3,3 ± 0,3), respectivamente. Nas imagens, observou-se que gHCl pode causar erosão do esmalte em ambos os grupos. Conclusão: O ácido clorídrico gasoso causa erosão do esmalte de forma semelhante em bovinos e humanos.Objective: To evaluate the action of gaseous hydrochloric acid on human and bovine enamel and compare the demineralization pattern of these substrates exposed to the gaseous erosive agent. Methods: Eight bovine enamel and eight human enamel specimens were obtained (4 × 4 × 2 mm), half surface was protected with composite resin and the other half was exposed to gaseous hydrochloric acid (gHCl), pH 2 at 37 °C, for 3 min, 8 times a day, for 12 days, and in intervals the specimens were maintained in artificial saliva. The specimens were analyzed according to wear profile, surface roughness and microhardness (before and after acid exposition). Data were statistically analyzed by one-way ANOVA. Results: Data showed no significant difference between bovine and human enamel for all properties analyzed – microhardness (98.1 ± 5.2, 96.9 ± 4.8), wear profile (11.5 ± 2.8, 11.4 ± 3.6) and roughness (2.6 ± 0.3, 3.3 ± 0.3), respectively. In images, we observed that gHCl could cause enamel erosion in both groups. Conclusion: Gaseous hydrochloric acid causes similar enamel erosion on bovine and humans

Resolução de conflitos na sala de aula

A pandemia da Covid-19 trouxe desafios inesperados a todos os professores do mundo e a seus alunos, e a volta às aulas presenciais veio acompanhada de novas dificuldades, como defasagem de conteúdos e novos problemas em conviver com o outro. A ausência prolongada de círculos sociais mais amplos transformou-se em um processo de descolamento da realidade escolar e ruptura do tecido social, além de dificultar o exercício da tolerância ao diferente, expresso nas figuras de colegas e professores. O trabalho, portanto, se deu com a intenção de reconectar os alunos ao espaço escolar, além de valorizar a coexistência entre os integrantes das turmas. [...

Tratamiento de aguas residuales provenientes de la industria

ABSTRACT: In the present study, the electrochemical degradation of textile dye indigo carmine (IC) was performed using dimensionally stable anodes (DSA) of Ti/IrO2-SnO2 doped with Sb2O5. The effect of different salts (NaCl, Na2SO4 and NaHCO3) used as supporting electrolyte was analyzed. The results showed that the oxidation dye IC is enhanced when NaCl is present in the solution due to the action of oxidizing species HClO/ClO- electro generated from the conductive medium. In the presence of NaCl, it was achieved a rapid removal of color and chemical oxygen demand. The results show the great potential of applying this technology to the treatment of wastewater from the textile industry.RESUMEN: En el presente estudio, la degradación electroquímica del colorante textil índigo carmín (IC) (3,3-dioxo-2,2-bi-indolilideno-5,5-disulfonato disódico) fue llevada a cabo utilizando ánodos dimensionalmente estables (DSA) de Ti/IrO2-SnO2 dopados con Sb2O5. El efecto de diferentes sales (NaCl, Na2SO4 y NaHCO3) como electrolito soporte fue analizado. Los resultados mostraron que la oxidación del colorante IC se mejora cuando hay presencia de NaCl en el medio de solución debido a la acción de las especies oxidantes HClO/ClO- electrogenerados a partir delmedio conductor. En presencia de NaCl, se logró una remoción rápida del color y de la demanda química en oxígeno. Los resultados obtenidos muestran el gran potencial de aplicación de esta tecnología al tratamiento de aguas residuales de la industria textil