Revista de la Academia de Ciencias Exactas, Físico-Químicas y Naturales de Zaragoza

None published between 1936-1946

Reacciones y protestas de agricultores e inmigrantes en El Ejido : Un municipio español inserto en las dinámicas de la globalización

El Ejido es una ciudad del sudeste español que ha pasado de ser una pequeña aldea dedicada a la agricultura de subsistencia, a principios de 1960, a tener en 2015 más de 85.000 habitantes. Este cambio se debe al desarrollo de una economía de invernaderos muy próspera que hoy está totalmente inserta en las dinámicas de la globalización. Tales dinámicas han ocasionado efectos contradictorios y han suscitado reacciones y/o formas de protesta diferentes en los dos principales actores sociales de El Ejido (los agricultores y los inmigrantes), entre los que se observan profundas asimetrías socioeconómicas y relaciones de explotación laboral. Como consecuencia, los inmigrantes y los agricultores viven en dos mundos sociales completamente diferentes y tienen percepciones y actitudes opuestas sobre la realidad, las cuales, a su vez, afectan a sus respectivas posibilidades y modos de reacción y/o de protesta

Aplicação da destilação simulada por cromatografia gasosa e da termogravimetria para a avaliação da influência da redução do teor de enxofre sobre as propriedades físico-químicas do óleo diesel

One of the main problems related to the use of diesel as fuel is the presence of sulfur (S) which causes environmental pollution and corrosion of engines. In order to minimize the consequences of the release of this pollutant, Brazilian law established maximum sulfur content that diesel fuel may have. To meet these requirements, diesel with a maximum sulfur concentration equal to 10 mg/kg (S10) has been widely marketed in the country. However, the reduction of sulfur can lead to changes in the physicochemical properties of the fuel, which are essential for the performance of road vehicles. This work aims to identify the main changes in the physicochemical properties of diesel fuel and how they are related to reduction of sulfur content. Samples of diesel types S10, S500 and S1800 were tested according with the methods of the American Society for Testing and Materials (ASTM). The fuels were also characterized by thermogravimetric analysis (TG) and subjected to physical distillation (ASTM D86) and simulated distillation gas chromatography (ASTM D2887). The results showed that the reduction of sulfur turned the fuel lighter and fluid, allowing a greater applicability to low temperature environments and safer for transportation and storage. Through the simulated distillation data was observed that decreasing sulfur content resulted in higher initial boiling point temperatures and the decreasing of the boiling temperature of the medium and heavy fractions. Thermogravimetric analysis showed a loss event mass attributed to volatilization or distillation of light and medium hydrocarbons. Based on these data, the kinetic behavior of the samples was investigated and it was observed that the activation energies (Ea) did not show significant changes throughout conversion. Considering the average of these energies, the S1800 had the highest Ea during the conversion and the S10 the lowest values

Transformações químicas, caracterizações e estudo de modelagem molecular do clerodano bioativo trans-desidrocrotonina

In this work it were developed synthetic and theoretical studies for clerodane-type diterpenes obtained from Croton cajucara Benth which represents one of the most important medicinal plant of the Brazil amazon region. Specifically, the majoritary biocompound 19-nor-clerodane trans-dehydrocrotonin (t-DCTN) isolated from the bark of this Croton, was used as target molecule. Semi-synthetic derivatives were obtained from t-DCTN by using the followed synthetic procedures: 1) catalytic reduction with H2, 2) reduction using NaBH4 and 3) reduction using NaBH4/CeCl3. The semi-synthetic 19-nor-furan-clerodane alcohol-type derivatives were denominated such as t-CTN, tCTN-OL, t-CTN-OL, t-DCTN-OL, t-DCTN-OL, being all of them characterized by NMR. The furan-clerodane alcohol derivatives t-CTN-OL and tCTN-OL were obtained form the semi-synthetic t-CTN, which can be isolated from the bark of C. cajucara. A theoretical protocol (DFT/B3LYP) involving the prevision of geometric and magnetic properties such as bond length and angles, as well as chemical shifts and coupling constants, were developed for the target t-DCTN in which was correlated NMR theoretical data with structural data, with satisfactory correlation with NMR experimental data (coefficients ranging from 0.97 and 0.99) and X-ray diffraction data. This theoretical methodology was also validated for all semi-synthetic derivatives described in this work. In addition, topological data from the Quantum Theory of Atoms in Molecules (QTAIM) showed the presence of H-H and (C)O--H(C) intramolecular stabilized interactions types for t-DCTN e t-CTN, contributing to the understanding of the different reactivity of this clerodanes in the presence of NaBH4.

Características físico-químicas, sensoriais e perfil de ácidos graxos do leite de cabras saanen alimentadas com cactáceas

The objective of this research was to evaluate the influence of the supply of five types of native and exotic cacti Brazilian semiarid northeast on the sensory characteristics of milk of Saanen goats. Five multiparous goats were used with nine weeks of lactation, average live weight of 50 kg ± 4 kg., confined and distributed in a Latin square design 5 x 5 with five experimental diets and five periods. Each period lasted 17 days, with 10 days of adaptation to the diets of the animals and seven days for the data collection. The treatments were defined based on dry matter consisted of: 47.33 to 50.12% of a cactus (“Xiquexique”, “Mandacaru”, “Facheiro” or two species of forage cactus “Miúda” or “Orelha de Elefante Mexicana”) more 18.78 to 19.79% hay of plant “Sabiá” and 31.10 to 32.89% of concentrate. There was not effect of the experimental diets in the physical and chemical composition of milk for fat, total solids and salts, which showed mean values of 3.24%; 11.30% and 0.66%, respectively. However the protein, lactose, nonfat dry extract and freezing point were affected by diets. In the profile of fatty acids was higher concentration of fatty short and medium chain fatty acids, however, there were not changes between treatments, except for the butyric acid (C4:0), with mean values of 4.24% (“Orelha de Elefante Mexicana”) to 6.05% (“Facheiro”). The diets also did not provide sensory changes in milk for the parameters: odor, flavor, aftertaste and overall assessment. The use of the five cactus in the diet of dairy goats do not influence the sensory characteristics and lipid profile of milk. The physical and chemical composition of milk was showed within the minimum requirements of current legislation, except for nonfat dry extract and freezing point.

Polpa de jambolão (Eugenia jambolana Lam.) fresca e desidratada: características físico-químicas, bioativas e funcionais, efeitos biológicos em Caenorhabditis elegans e uso para produção de frozen yogurt caprino probiótico

This work evaluated the fresh, spray dried (with 10 % of Arabic Gum) and freeze dried jambolan pulp (Eugenia jambolana Lam.) in regard to physicochemical (pH, moisture, water activity, average particle diameter, solubility and color), bioactive [total phenolic content (TPC), monomeric anthocyanin, pronathocyanidin (PA), total elagic acid (TEA), myricetin and cyanidin] and in vitro functionality (antioxidant, antienzymatic and antimicrobial activities]. In addition, the in vivo functionality of jambolan pulp was investigated using the Caenorhabditis elegans model for insulin signaling, longevity and induced neurodegeneration (Alzheimer’s disease and Parkinson’s disease related symptoms). The dried jambolan pulp presented TPC retention (50% to 75%), PA (90% to 98%), TEA (31% to 83%), myricetin (40% to 84%), cyanidin (72% to 84%) and antioxidant activity (15%). The fresh jambolan pulp, the freeze dried pulp and the spray dried jambolan pulp presented high enzymatic inhibitory activity against pancreatic lipase (4,4 to 5,8 mg/mL), alpha-glycosidase (10,3 to 13,8 mg/mL) and alpha-amylase (8,9 to 11,2 mg/mL). They also were active inhibitors against the pathogen S. aureus. The dried jambolan experimental samples were able to increase the expression of several genes linked to the insulin signaling pathways (SIR-2.1, PPTR-1, DAF-16, SOD-3, e CTL) and increased the lifespan in C. elegans (18,07 % - 24,34 %), besides decreasing the amyloid AB1-42 aggregation induced paralysis and MPP+ (1-methyl-4-phenylpyridinium) induced neurodegeneration. Based on that, the jambolan pulp and the spray dried jambolan pulp were further selected for the production of caprine frozen yogurt with the addition of Bifidobacterium animalis subsp. lactis BI-07. The final product were evaluated in regard to their physicochemical (pH, acidity, total solids, protein, total reducing sugars, fat, ashes, overrun, melting test), bioactive (TPC and monomeric anthocyanin, antioxidant activity, probiotic viability and sensory analysis (sensory acceptance). The results showed that samples with probiotic had lowest pH and higher acidity, TPC, anthocyanin and antioxidant activity. It was also observed low overrun (14.2% to 22.6%). vi Samples with probiotic had lower flavor scores. Overall, this research presents the jambolan as a highly functional bioactive-rich fruit with the potential to modulate important biological pathways, extend lifespan and retard the development of neurodegenerative diseases. Jambolan is an underexploited exotic fruit with a high colorant potential and this thesis shows for the first time in the literature important technological, biological and scientific data about this fruit that could be used towards the development of health-oriented food products.

O Ensino de ligações químicas por meio do conceito de energia: uma proposta didática para o ensino médio

This work presents discussions on the teaching of Chemical Bonds in high school and some implications of this approach in learning chemistry by students. In general, understanding how the chemicals combine to form substances and compounds, it is a key point for understanding the properties of substances and their structure. In this sense, the chemical bonds represent an extremely important issue, and their knowledge is essential for a better understanding of the changes occurring in our world. Despite these findings, it is observed that the way in which this concept is discussed in chemistry class has contributed, paradoxically, to the emergence of several alternative designs, making the understanding of the subject by students. It is believed that one of the explanations for these observations is the exclusive use of the "octet rule" as an explanatory model for the Chemical Bonds. The use of such a model over time eventually replace chemical principles that gave rise to it, transforming knowledge into a series of uninteresting rituals and even confusing for students. Based on these findings, it is deemed necessary a reformulation in the way to approach this content in the classroom, taking into account especially the fact that the explanations of the formation of substances should be based on the energy concept, which is fundamental to understanding how atoms combine. Thus, the main question of the survey and described here of the following question: Can the development of an explanatory model for the Chemical Bonds in high school based on the concept of energy and without the need to use the "octet rule"? Based on the concepts and methodologies of modeling activity, we sought the development of a teaching model was made through Teaching Units designed to give subsidies to high school teachers to address the chemical bonds through the concept of energy. Through this work it is intended to make the process of teaching and learning of Chemical Bonds content becomes more meaningful to students, developing models that contribute to the learning of this and hence other basic fundamentals of chemistry.

El estrés y la velocidad de anticipación en los "Call Centers"

La presente tesis doctoral se enmarca dentro del programa de doctorado del Departamento de Psicología Evolutiva y de la Educación, de la Facultad de Educación de la Universidad Complutense de Madrid. Este trabajo, realizado durante los últimos 9 años, tiene como motivo principal la identificación de un perfil adecuado a las necesidades del trabajo en un Call Center, de modo que tanto trabajador como empresa puedan salir beneficiados. Asimismo, se pretende detectar patrones de actividad laboral en esta población, que identifique los momentos apropiados para realizar descansos tras un cierto tiempo de actividad dentro de la jornada laboral, de manera que se pueda disminuir el estrés y por tanto permitir que el agente pueda seguir desarrollando un trabajo eficaz. Nos encontramos con una actividad profesional que exige alta concentración y atención, provocando elevados índices de estrés. La consecuencia inmediata es el elevado porcentaje de absentismo y bajas voluntarias que se dan en este sector. Por lo que, si este tipo de empresas tienen trabajadores con un perfil profesional adecuado a sus necesidades, no solo cumplirán sus objetivos de negocio sino que es posible que puedan mejorarlos, disminuyendo así mismo la rotación y el absentismo, aumentando la productividad y mejorando la calidad de vida y el clima laboral. La elección de este tema está relacionada con mi actividad profesional. En los últimos 15 años he desarrollado mi actividad profesional en el ámbito de la selección de personal y Recursos Humanos. En concreto desde el 2006 he desempeñado mi actividad para una conocida empresa financiera. En Marzo del 2007 arrancamos un proyecto para la selección de agentes de Call Center. Me sorprendió en aquel momento tanto el perfil de los candidatos como, una vez iniciada la actividad, el alto nivel de absentismo y bajas voluntarias que se producían...

Velocidad de anticipación y trastorno por déficit de atención e hiperactividad

Resulta innegable que la conducción de vehículos constituye, en sí, el ejercicio de una actividad multitarea compleja. De manera tal que, quien quisiera ejecutarla, deberá poseer determinadas aptitudes psíquicas y físicas que aseguren, en todo momento, el mantenimiento de óptimas condiciones de seguridad. Por un lado, los datos de investigación, así como las estadísticas de siniestralidad vial, indican que son varios factores los que inclinan la balanza hacia una mayor propensión de conductas de riesgo en la conducción por parte de los adolescentes: la combinación de inmadurez e inexperiencia, no utilizar el cinturón de seguridad, acelerar o conducir demasiado rápido, el alto consumo de tecnología mientras conducen, etc. Por otro lado, la distracción y la inatención son factores humanos concurrentes en los accidentes de tráfico. Se ha considerado abordar la distracción y la inatención como aspectos continuos e inherentes a la persona bajo el Trastorno por Déficit de Atención e Hiperactividad (TDAH). Catalogado como un trastorno que se manifiesta por presentar dificultades crónicas para mantener la concentración (déficit de atención), sobre todo en circunstancias que ofrecen baja estimulación, y la falta de inhibición/control sobre los impulsos asociada con frecuencia a inquietud motora (impulsividad-hiperactividad) y que interfieren, visiblemente, en el desarrollo del individuo y, con un papel muy notorio, en los ámbitos clínico, social, asistencial, académico y, por supuesto, seguridad vial. Apenas se conoce la sensibilidad/capacidad de la prueba psicotécnica, velocidad de anticipación, utilizada en los Centros de Reconocimiento de Conductores para la obtención o renovación del carné de conducir en España, como instrumento para detectar sujetos con TDAH. El objetivo del presente estudio es comparar el desempeño en la prueba psicotécnica que mide la velocidad de anticipación, a través del Test KCC, en una muestra de 173 sujetos, niños y adolescentes, de ambos sexos, entre los 7 y 16 años con y sin TDAH y, si otras variables, como el sexo, la edad, el índice de reflexividad/impulsividad (a través del Test de Stroop) y el potencial de aprendizaje (medido con el Test TONI-2) también influyen. Los resultados obtenidos muestran que no existen diferencias estadísticamente significativas entre niños y adolescentes con o sin TDAH para las variables de velocidad de anticipación, edad, sexo e índice de reflexividad/impulsividad. Sin embargo, si se encontraron diferencias estadísticamente significativas en relación al potencial de aprendizaje (CI) y la medida, velocidad de anticipación. Se recomienda efectuar estudios confirmatorios e investigaciones que repliquen y evalúen estas variables.

O Ensino de ligações químicas por meio do conceito de energia: uma proposta didática para o ensino médio

This work presents discussions on the teaching of Chemical Bonds in high school and some implications of this approach in learning chemistry by students. In general, understanding how the chemicals combine to form substances and compounds, it is a key point for understanding the properties of substances and their structure. In this sense, the chemical bonds represent an extremely important issue, and their knowledge is essential for a better understanding of the changes occurring in our world. Despite these findings, it is observed that the way in which this concept is discussed in chemistry class has contributed, paradoxically, to the emergence of several alternative designs, making the understanding of the subject by students. It is believed that one of the explanations for these observations is the exclusive use of the "octet rule" as an explanatory model for the Chemical Bonds. The use of such a model over time eventually replace chemical principles that gave rise to it, transforming knowledge into a series of uninteresting rituals and even confusing for students. Based on these findings, it is deemed necessary a reformulation in the way to approach this content in the classroom, taking into account especially the fact that the explanations of the formation of substances should be based on the energy concept, which is fundamental to understanding how atoms combine. Thus, the main question of the survey and described here of the following question: Can the development of an explanatory model for the Chemical Bonds in high school based on the concept of energy and without the need to use the "octet rule"? Based on the concepts and methodologies of modeling activity, we sought the development of a teaching model was made through Teaching Units designed to give subsidies to high school teachers to address the chemical bonds through the concept of energy. Through this work it is intended to make the process of teaching and learning of Chemical Bonds content becomes more meaningful to students, developing models that contribute to the learning of this and hence other basic fundamentals of chemistry.

Estudo das características físico-químicas e biológicas pela adesão de osteoblastos em superfícies de titânio modificadas pela nitretação em plasma

SILVA, J. S. P. Estudo das características físico-químicas e biológicas pela adesão de osteoblastos em superfícies de titânio modificadas pela nitretação em plasma. 2008. 119 f. Tese (Doutorado) - Faculdade de Medicina, Universidade de São Paulo. São Paulo, 2008.

Las nubes de alta velocidad de la galaxia y la estructura del gas interestelar

Este trabajo presenta resultados que se proponen aclarar ulteriormente,los aspectos morfológicos y termodinámicos del medio interestelar en las regiones periféricas de la galaxia.Se divide en una parte de análisis eminentemente teórico,en el cual se postura una estructura jerárquica del gas, en tres fases de temperatura y densidades distintas. Y en una parte de carácter observacional,en el cual se presentan los resultados de observaciones radioastronómicas que tienden a corroborar los resultados teóricos.El cuadro resultante propuesto por este estudio es el de un gas galáctico periférico conformado en estructuras nebulares, que participan en la rotación galáctica y que estando presumiblemente a grandes distancias,presentan altos valores de la velocidad radial; pueden ser interpretadas como representativa de dos fases en equilibrio de presión, térmico y de ionización entre ellas y con una tercera fase, “internebular”,a temperatura mayor que 20000º K.

Estudo das características físico-químicas e biológicas pela adesão de osteoblastos em superfícies de titânio modificadas pela nitretação em plasma

SILVA, J. S. P. Estudo das características físico-químicas e biológicas pela adesão de osteoblastos em superfícies de titânio modificadas pela nitretação em plasma. 2008. 119 f. Tese (Doutorado) - Faculdade de Medicina, Universidade de São Paulo. São Paulo, 2008.

Obtenção de concentrado proteico do farelo de arroz e avaliação das propriedades químicas e funcionais

Esta dissertação é composta por 5 artigos.