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Mexico City, Mexico

Moller A.,Avenida University 3000 | Hansen A.M.,Instituto Mexicano Of Tecnologia Del Agua
Applied Geochemistry | Year: 2012

A zero-dimensional model for the environmental fate of ethylenethiourea (ETU) in soils was formulated. The relevant physicochemical transformation processes were derived from published data, and their dynamics analyzed. Corresponding kinetic submodels for sorption, photodegradation, abiotic oxidation and biodegradation were then developed based on assumptions on the dominant process mechanisms. These submodels, and the overall model of biotic degradation in soil, were applied to literature data with determination coefficients of R 2>0.9, validating the assumed process dynamics. © 2012 Elsevier Ltd. Source


Martinez-Mayorga K.,Avenida University 3000 | Peppard T.L.,Robertet Flavors Inc. | Lopez-Vallejo F.,Torrey Pines Institute for Molecular Studies | Yongye A.B.,Torrey Pines Institute for Molecular Studies | Medina-Franco J.L.,Torrey Pines Institute for Molecular Studies
Journal of Agricultural and Food Chemistry | Year: 2013

Bioactive food compounds can be both therapeutically and nutritionally relevant. Screening strategies are widely employed to identify bioactive compounds from edible plants. Flavor additives contained in the so-called FEMA GRAS (generally recognized as safe) list of approved flavoring ingredients is an additional source of potentially bioactive compounds. This work used the principles of molecular similarity to identify compounds with potential mood-modulating properties. The ability of certain GRAS molecules to inhibit histone deacetylase-1 (HDAC1), proposed as an important player in mood modulation, was assayed. Two GRAS chemicals were identified as HDAC1 inhibitors in the micromolar range, results similar to what was observed for the structurally related mood prescription drug valproic acid. Additional studies on bioavailability, toxicity at higher concentrations, and off-target effects are warranted. The methodology described in this work could be employed to identify potentially bioactive flavor chemicals present in the FEMA GRAS list. © 2013 American Chemical Society. Source


Pre-service and in-service teachers' training has been the focus of several programs developed in Brazil. Among them, the called "Institutional Program of Teaching Training Scholarship" (in Portuguese "Programa Institucional de Bolsa de Iniciação à Docência-pibid") is really remarkable, which has as its main goal improving the academic actions for pre-service teachers training. This study has the aim to analyze the transformation of knowledge and beliefs of future chemistry teachers - scholarship holders of pibid - on the topic "Nature of Matter", to make it comprehensible to high school students. That is, documenting and discussing the development of Pedagogical Content Knowledge (pck) of each one of these scholars during the design and application of a didactic unit on the topic. The research was done with four scholars of the Program, students of a chemistry career in a public Brazilian University. Two elements were considered to show the improvements of the participants pck: an initial interview in which the eight questions of the Content Representation of Loughran etal. (2004) were posed, and afterwards the Didactic Unit produced and applied to high school students. Main results show the appropriation for students of enough knowledge for the adequate performance in the classroom, it stimulated by the actions pibid contemplates. © Universidad Nacional Autónoma de México. Source


Hernandez-Ortiz S.,Universidad Michoacana de San Nicolas de Hidalgo | Murguia G.,Avenida University 3000 | Raya A.,Universidad Michoacana de San Nicolas de Hidalgo
Journal of Physics Condensed Matter | Year: 2012

Using irreducible and reducible representations of the Dirac matrices, we study the two- and four-component quantum mechanical supersymmetric (SUSY) theories for ultrarelativistic fermions in (2+1) dimensions (graphinos) in a background uniform magnetic field perpendicular to their plane of motion. We then consider ordinary and parity-violating mass terms and identify the former as a soft SUSY breaking term and the latter as the hard SUSY breaking one. © 2012 IOP Publishing Ltd. Source


Chavez O.,Avenida University 3000 | Mendez F.,Avenida University 3000
Applied Thermal Engineering | Year: 2011

In this work, we analyze theoretically the conjugate heat conductive mechanism resulting from an alternating electrical current that flows continuously in an aluminum conductor steel reinforced (ACSR), taking into account that the electric resistivity is dependent on temperature. This last consideration conducts us to analyze simultaneously the electrical and thermal effects in both conductor materials. In this manner, we need to solve a double conjugate thermo-electric model. In addition, the presence of skin effect causes significant radial temperature differences, since for high frequencies the electric current tends to flow over the surface of the conductor and therefore, the heat generation produced by Joule effect, is no uniform. Based on an equation for predicting the alternating current density and described by a non-linear wave equation, numerical solutions for the above equation together with the heat conduction equation are possible to predict the current density and the temperature profiles. In particular, the influence of the environmental convective conditions, the skin effect and the influence of the variable resistivity on current density and temperature fields, are clarified. The above effects show that the electrical and thermal operation of the electrical networks can be subject to several factors that made, in general, more difficult the full utilization of the electrical transport. © 2011 Elsevier Ltd. Source

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