El oscilador salino.

Estudio sobre el oscilador salino y su aplicación a las prácticas de la clase de ciencias. En 1970 Seelye Martin, de la Universidad de Washington, descubrió un curioso efecto basado en la diferencia de densidad de dos líquidos. Tal efecto puede ser observado fácilmente si se llena un recipiente alto de vidrio, como por ejemplo una probeta, con agua de manera que el nivel de ésta llegue casi hasta el borde del recipiente. Tomando luego un vasito de plástico de paredes finas, y poniendo en él un líquido coloreado de mayor densidad que el agua, se sumerge el vaso hasta que los niveles de ambos líquidos coincidan. Si a continuación se practica en el fondo del vaso un orificio con ayuda de un alfiler podrá verse cómo una fina vena de líquido coloreado desciende a través del agua. Este flujo descendente está motivado por el hecho de que en la interfase que separa a ambos líquidos la presión ejercida hacia abajo por el líquido coloreado es mayor que la presión ejercida hacia arriba por el agua. Este fenómeno se aprecia muy bien si en el vaso se pone una disolución de sal común en agua. Por este motivo al mencionado dispositivo se le da el nombre de oscilador salino. A continuación, y con el objeto de construir una práctica de laboratorio para alumnos basada en el oscilador salino, se procede a un estudio teórico previo del mismo y posteriormente se realiza un experimento, al objeto de comprobar el cumplimiento de la expresión teórica obtenida por nosotros para el oscilador salino. Para terminar se señala que la práctica reflejada fue realizada por los alumnos de Física de COU del Instituto Ramiro de Maeztu, de Vitoria, con buenos resultados, invirtiendo tres horas en su realización.

El agua y el suelo : dos sistemas vitales en peligro : un proyecto de educación ambiental para educación secundaria.

Incluye un folleto con la fundamentación teórica de los temas transversales. No consta centro realizador

El suelo, un soporte vital : experiencias didácticas en torno al jardín de tu instituto.

Fecha aproximada 1990

Evaluación de métodos de simulación informática en Enseñanzas Técnicas Superiores : aplicación a la mecánica del suelo.

El trabajo, dentro de una línea de actualización tecnológica y docente, intenta reorientar los objetivos de la asignatura, tanto en el desarrollo de clases teóricas, como en los contenidos de las clases prácticas para conseguir un mejor aprovechamiento del horario docente y una mejor calidad de la formación impartida. Dentro de este marco tiene gran importancia el desarrollo de programas de simulación en ordenador de los contenidos. Alumnos de cuarto curso de Ingeniería de Caminos. Estructuración de una parte cuatrimestral del programa de prácticas. Diseño de programas de ordenador para realizar las prácticas. A modo de variable independiente actúa el nuevo método didáctico (un sólo grupo experimental). Como variable dependiente evalúan las calificaciones obtenidas en otros exámenes: Examen de diciembre (no incluye el nuevo método). Examen final de febrero (no incluye el nuevo método). Test específico del programa. Examen de septiembre (incluye una pregunta referida al nuevo método con una ponderación 1/18). Test elaborado ad hoc con 10 ítems de respuesta múltiple. Calificaciones obtenidas a lo largo del curso.. Distribuciones de frecuencia. Correlación. Regresión. No se observa ninguna mejora en las calificaciones debidas a la utilización del nuevo método.. Destacan la incongruencia con un estudio anterior donde sí encontraron diferencias significativas. Como explicación de la falta de eficacia del método proponen tres razones: que el alumno no esté acostumbrado a este tipo de metodología; que la adecuación de los programas desarrollados sea escasa, o que el diseño de las actividades no sea el adecuado. Por último remarcan que la calidad de presentación de los programas no ha sido adecuada. El trabajo incluye los programas desarrollados y el test elaborado.

La tasa por utilización de suelo público y por publicidad exterior en los Municipios de Azogues y Cuenca. Análisis jurídico tributario

La presente investigación está centrada en el régimen impositivo tributario seccional; cuyo enfoque principal esta dirijo al análisis de dos ordenanzas municipales, las cuales fueron emitidas por los Gobiernos Autónomos Descentralizados de Azogues y Cuenca, en donde se imponen prestaciones patrimoniales públicas en base de la utilización de bienes de dominio público, la primera mediante el establecimiento de un servicio de estacionamiento rotativo tarifado y la segunda con la finalidad de permitir la colocación de publicidad en los medios de transporte dentro del respectivo Cantón. El objetivo buscado con esta investigación es identificar cuál es la naturaleza jurídica de dichas prestaciones y determinar si estamos frente a una prestación tributaria, específicamente una tasa. Este análisis se lo realizó en base a un estudio previo de la teoría doctrinaria sobre la tasa, buscando instrumentos que nos permitan individualizarla para entender su origen y razón de ser; además de realizó una revisión de sus características y elementos para distinguirla de otras prestaciones patrimoniales; de igual forma se tomó como pilar fundamental de este trabajo las disposiciones constitucionales y legales que regulan a esta clase de tributo. Todo este esfuerzo nos ha permitido evidenciar como se está aplicando la tasa dentro de los gobiernos municipales, concebida esta, como instrumento generador de ingresos en pos de lograr una independencia financiera; al igual que nos ha posibilitado identificar respecto de los casos en estudio, si se están cumpliendo con los requisitos tanto de fondo cuanto de forma necesarios para su pleno establecimiento y validez. Finalmente, nos permitimos establecer recomendaciones dirigidas hacia una correcta aplicación de la potestad tributaria que ostentan los gobiernos subnacionales, es decir, procurando que el ejercicio de dicha facultad guarde armonía y respeto a las regulaciones establecidas por la ley, lo que a nuestro entender constituye el camino adecuado que garantizará la no afectación de los derechos de los ciudadanos.

Estresse salino associado à aplicação exógena de espermidina no acúmulo de glicina betaína em Guandu

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comportamento de mudas de nim à salinidade da água em solo não salino com biofertilizante

An experiment was carried out in greenhouse during the period January to April 2010, at Center of Agricultural Sciences of the Federal University of Paraiba, in Areia, Paraiba State, Brazil, in order to evaluate the effects of saline water and bovine biofertilizer on the seedling growth of Indian neem. The substrate was material of a non-saline soil collected in depth of 0-20 cm. The treatments were arranged in a completely randomized design using a 5 x 2 factorial, referring to salinity levels of irrigation water of 0.5, 1.0, 2.0, 3.0 and 4.0 dS m(-1), with and without bovine biofertilizer applied to the soil only once after dilution with water (1: 1), a day before sowing, in volume corresponding to 10% of the substrate. At 86 days after emergence of seedlings the plant growth in height and principal root length, diameter of stem and root, leaf number and dry mass of roots and shoots of plants were evaluated. The salinity of irrigation water increased the salinity levels in the substrate inhibiting the growth in height, stem diameter, leaf emission by plants, diameter and length of principal root and the dry matter production of roots and aerial parts (leaves + stem) of neem, but with less pronounced decrease in plants under the treatments with bovine biofertilizer.

Influência do estresse hídrico e salino na germinação de urochloa decumbens e urochloa ruziziensis

Studies of the germination response of seeds subjected to artificial stresses are provided tools for better understanding of the survivability and adaptation of these species in natural stress conditions such as drought or saline soils, common in agricultural and forest regions, contributing significantly to the development of management strategies. Thus, the purpose of this study was to evaluate the possible effects of water and salt stress on germination of Urochloa decumbens and Urochloa ruziziensis. The test was conducted at the Faculty of Technology of São Paulo, campus of Capon Bonito. The seeds were sown with four replicates of 50 seeds in paper soaked in solutions with the potentials of 0.0, -0.2, -0.4 and -0.8 MPa, induced with polyethylene glycol (PEG 6000) and NaCl. The germination test was conducted at 25 degrees C in the presence of light, evaluating the first test score at seven days after sowing, and weekly germination (normal seedlings) until 35 days. We calculated the index of germination rate. The results allowed the conclusion that water stress causes a greater reduction in force, speed of germination and cumulative germination of seeds of U. decumbens and U. ruziziensis than salt stress. The species U. decumbens showed higher tolerance to water and salt stresses.

Impactos do estresse salino e da cobertura morta nas características químicas do solo e no desenvolvimento do amaranto

Availability of good quality water has been reduced vertiginously, over the last decade, in the world. In some regions, the water resources have high concentration of the dissolved salts, these characteristics of the water make it s use impossible. Water quality can be a limitation for irrigated agriculture, principally in regions of arid or semiarid climate where the water resources are generally saline and are exposed at high evaporation ratio. For that reason, precipitation of the salts occurs near the soil surface and those salts themselves cumulate in the vegetal tissue, reducing the soil fertility and crop production. The adoption of tolerant crop to the water salinity and soil salinity, adaptable to the climatic conditions is other emergent necessity. This work had the goal of studying the effects of four salinity levels of the irrigation water salinity and use of mulch, dried leaves of Forest mangrove (Acacia mangiumWilld), in cultivated soil with amaranth (Amaranthus cruentus, BRS Alegria variety), in greenhouse. It was utilized the transplant of plants to PVC columns, containing 30 kg of silty loam soil, 10 days after emerging, with space of 50 x 50 cm between lines. Treatments were composed by combination of four levels of salinity (0.147; 1.500; 3.000 e 4.500 dS m-1), obtained by addition NaCl (commercial) to irrigation water and soil with and without protection, by mulch. A factorial system 4 x 2 was used with four repetitions, totalizing 32 parcels. The concentrations of nutrients in soil solution have been evaluated, in the dry matter of the vegetal tissue (roots, stem, leaves and raceme residue), at the end of the vegetative cycle. The use of soil protection reduced time for the beginning inflorescence of plants, at the same time, the increase of the salinity delayed this phase of amaranth development. The use of the mulch effectively increased the height, stem diameter, area of the larger leaf, humidity and dry matter content and amaranth grain production. The vegetal species showed salinity tolerance to experimented levels. The adopted treatments did not affect the pH values, exchangeable cation contents, electrical conductivity of soil solution (EC1:5) and saturated extract (ECSE), and Ca+2, Mg+, Fe+2 and Mn+2 contents, in the soil solution. The increase of the salinity concentration in the irrigation water inhibited the mineralization process of the organic matter (OM) and, consequently, the efficiency in the it´s utilization by plants, at the same time, produced increase in the values of the exchangeable sodium percentage (ESP), sodium adsorption ratio (SAR) and potassium adsorption ratio (PAR), in the soil solution. Therefore, the use of the mulch did not affect the first three parameters. The protein and nutrient contents: K+, Ca+2, P, Mg+2 e Cu+2, in amaranth grains, were improved by tillage condition. The raceme residues showed chemical/nutritional composition that makes advantageous its application in animal ration. In this context, it follows that amaranth tolerate the saline stress, of the irrigation water, until 4.500 dS m-1, temperature and relative humidity of the air predominant in the experimental environment

Estado nutricional e componentes da produção de plantas de pimentão conduzidas em sistema de fertirrigação durante indução de estresse salino em cultivo protegido

O uso das técnicas de fertirrigação em ambiente protegido vem aumentando no Brasil devido à praticidade de condução e redução dos custos de produção. Apesar dessas vantagens, salienta-se que esta prática também pode trazer riscos, principalmente pelo acúmulo de sais na superfície do solo e na região periférica do bulbo radicular. em caso de salinização do solo pelo manejo incorreto do sistema podem ocorrer alterações na disponibilidade de nutrientes, com conseqüências fisiológicas no desenvolvimento das plantas. Neste trabalho, utilizou-se o pimentão (Capsicum annuum L.) como planta-modelo para estudos da interferência da salinidade na nutrição das plantas, pela alteração da condutividade elétrica (CE) na solução do solo. Os resultados revelaram indícios de antagonismo entre nutrientes, notadamente entre as formas catiônicas em razão do aumento da concentração de KCl nos tratamentos com alta CE. A suplementação do solo com adubo orgânico não atenuou os efeitos do aumento da concentração salina e os valores extremos de CE interferiram drasticamente na produção.

Qualidade fisiológica de sementes de genótipos de algodoeiro sob estresse salino

The germination of cotton seeds and the seedlings emergency are generally delayed and reduced by the salinity. Although the cotton is considered a tolerant culture, it can suffer substantial reductions in regarding its growth and production when exposed to salinity condition. The aims of this study went evaluate the effect of the saline stress in the germination phase to four cotton genotypes (BRS Rubi, BRS Safira, BRS 201 and CNPA 187 8H), using different osmotic potentials generated with increment of sodium chloride (NaCl). The saline stress was simulated using NaCl aqueous solutions in the potentials: 0.0 (Control); -0.2; -0.4; -0.6; -0.8 and -1.0 MPa. The treatments were monitored by means of tests for analysis of seeds, germination, first counting, speed germination index, length of shoot, radicle length, dry weigth of embrionic axis and shoot/radicle ratio. The tests for germination, first counting and index of germination speed were accomplished using 50 seeds for repetition and for the study of length of shoot, radicle length, dry weigth of embrionic axis and shoot/radicle ratio were used 20 seeds by repetition. For both tests four repetitions were accomplished by genotype for each one of the potentials. The seeds of each repetition were involved in papers Germitest humidified with NaCl solution corresponding to the potential. The repetitions of both tests were maintained in a germinator with saturated humidity. The analysis were initiate four days after the induction of the saline stress. The evaluations of the first three variables analyzed were accomplished daily; the seeds were remove and counted when its germinated. For the length tests just the repetitions corresponding to the potential of NaCl 0,0 MPa were analysis 4 days after the beginning of the induction of the saline stress. The analysis of the repetitions of the potentials -0,2 and -0,4 and of the potentials -0,6, -0,8 and -1,0 MPa they were accomplished with 12 and 20 days, respectively. For accomplishment of the analisis of this test the shoot of the 20 plantules of each repetition was separate from the radicle and both parts were measured. The statistical analyses were performed using the GENMOD and GLM procedures of the SAS. For the variable germination, the cultivates CNPA 187 8H and BRS Safira stood out for the potential -0.8 MPa, with averages of 89% and 81%, respectively. The test of speed germination index to cultivate BRS Safira presented the largest averages for the two higher saline potentials. It was observed that the increase of the saline potential reduces the germination percentage and speed germination index. For each day of evaluation it was verified that the increase of the saline potential causes a reduction of the length both of the shoot and of the radicle. The radicle tends to grow more than the shoot until the potential -0,4 MPa

Inibição à corrosão do aço AISI 1020, em meios ácido e salino, por tensoativos e substâncias nitrogenadas microemulsionados

Corrosion inhibition efficiency of saponified coconut oil (SCO) and sodium dodecilbenzene sulfonate (DBS) surfactants in AISI 1020 carbon steel was evaluated by electrochemical methods. These surfactants were also evaluated as microemulsion systems (SCO-ME and DBS-ME), of O/W type (water-rich microemulsion), in a Winsor IV region. They were obtained according to the following composition: 15% SCO, 15% butanol (30% Co-surfactant/Surfactant C/T), 10% organic phase (FO, kerosene) and 60% aqueous phase (FA). These systems were also used to solubilize the following nitrogenated substances: Diphenylcarbazide (DC), 2,4-dinitro-phenyl-thiosemicarbazide (TSC) and the mesoionic type compound 1,3,4-triazolium-2-thiolate (MI), that were investigated with the purpose of evaluating their anticorrosive effects. Comparative studies of carbon steel corrosion inhibition efficiencies of free DBS and DBS-ME, in brine and acidic media (0.5%), showed that DBS presents better inhibition results in acidic media (free DBS, 89% and DBS-ME, 93%). However, the values obtained for DBS in salted solution (72% free DBS and 77% DBS-ME) were similar to the ones observed for the SCO surfactant in brine (63% free SCO and 74% SCO-ME). Analysis of corrosion inhibition of the nitrogenated substances that were solubilized in the SCO-ME microemulsion system by the linear polarization method in brine (0.5% NaCl) showed that such compounds are very efficient an corrosion inhibitors [DC-ME-SCO (92%), TSC-ME-SCO (93%) and MI-ME-SCO (94%)]

Expressão diferencial dos genes VuUCP1a e VuUCP1b em caupi sob estresse salino

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Reação enzimática ao estresse salino durante a germinação de estilosantes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Alterações na atividade da peroxidase e do conteúdo de carboidratos em mandioca cultivada in vitro sob estresse salino

A influência de estresse induzido por cloreto de sódio (75 e 150 mM) sobre o conteúdo de carboidratos solúveis e atividade da peroxidase, foi estudada em plântulas de mandioca cultivadas in vitro. Os resultados mostraram que a atividade da peroxidase diminuiu gradualmente durante o crescimento de plântulas em todos os tratamentos. O conteúdo de açúcares redutores foi menor em plântulas submetidas a 75 mM de NaCl, nas fases mais adiantadas do desenvolvimento, em comparação com a dose mais elevada do sal (150 mM de NaCl) ou sua omissão. Os resultados obtidos indicaram que o NaCl alterou o metabolismo de carboidratos, atividade da peroxidase e o crescimento de plântulas cultivadas in vitro.