Modificação de um micro-extrator de vidro para pré-enriquecimento de traços de pesticidas organoclorados de água para análise por cromatografia gasosa

Two models of a glass micro-extractor were constructed after modification of a model proposed in the literature. The two models were used for the simultaneous extraction and enrichment of organochlorinated pesticides from aqueous matrixes to an organic solution appropriate for the gas chromatographic analysis of the pesticide. It was established that the performance of one of the modified micro-extractors permits the pre-concentration of the pesticides to a level that allow their quantitation at the trace level with electron capture detection. It is thus concluded that the glass micro-extractor is a suitable tool for the sample preparation step in the gas chromatographic analysis of environmental pollutants of the class of pesticides.

Aplicação de SPME (Solid Phase Micro-Extraction) na análise de águas potáveis de três localidades do estado de São Paulo

The technique of solid phase microextraction (SPME) was used for the extraction of halogenated contaminants of water samples from three cities of the State of São Paulo and the extracts were submitted to gas chromatographic analysis with electron capture detection (GC-ECD). In the samples of water collected at the city of São Paulo the detected level of trihalomethanes (THM) expressed as the sum of chloroform, dibromochloromethane and dichlorobromomethane, were higher than the permissible limit established by the Brazilian regulation. In the samples collected at the two other cities the level of any of the three THM remained below the sensitivity of the ECD.

Nitração do fenol, um método em escala semi-micro para disciplina prática de 4 horas

A procedure for the nitration of phenol in a semi-micro scale, followed by separation of the formed orto- and para-nitrophenol isomers by column chromatography, is described. All the experiment, including determination of the melting point of the isolated products, require a period of 4 hours, and it is suitable for organic chemistry laboratory undergraduate courses.

Extração em fase sólida (SPE) e micro extração em fase sólida (SPME) de piretróides em água

The pyrethroids bifenthrin, permethrin, cypermethrin and deltamethrin were extracted by solid phase extraction (SPE) and solid phase microextraction (SPME). The analysis were performed on a gas chromatograph with electron capture detection (GC-ECD). Octadecil Silano-C18, Florisil and Silica stationary phases were studied for SPE. Better results were obtained for Florisil which gave recoveries from 80% to 108%. Pyrethroids extraction by SPME showed a linear response and a detection limit of 10 pg ml-1. Although the data showed that the two extraction methods were able to isolate the pesticide residues from water samples, the best results were obtained by using SPME which is more sensitive, faster, cheeper, being a more useful technique for the analysis of pyrethroids in drinking water.

Pré-concentração de chumbo e cádmio em um sistema de micro extração líquido-líquido e determinação por espectrometria de absorção atômica com chama

A method for determination of lead and cadmium in aqueous samples using solvent microextraction and dithizone as complexing agent with FAAS was developed. Solvent microextraction parameters were optimized. The effect of foreign ions on the extraction yields was studied. The extraction was carried out until the aqueous to organic phase ratio achieved a 250 fold preconcentration of metals. For preconcentration times of 4 min the 3sigma detection limits, relative standard deviations (n=7) and linear calibration ranges were 1.6 mug L-1, 5.8% and 10.0 -- 80.0 mug L-1 for lead and 11.1 ng L-1, 5.9% and 0.3 -- 3.0 mug L-1 for cadmium, respectively. The solvent microextraction procedure presented here was applied to the determination of lead and cadmium in natural waters.

La distribución regional de la temporalidad en españa. Análisis de sus determinantes

Este trabajo aporta evidencia empírica acerca de los factores determinantes de las diferencias en la probabilidad de acceder a un contrato indefinido entre las distintas regiones españolas. Para ello, y de forma novedosa en este contexto, se aplica una extensión de la metodología tradicional de Oaxaca-Blinder al caso de modelos no lineales. Los resultados apuntan a la coexistencia de distintas “culturas de la temporalidad” en España, al existir discrepancias regionales significativas en el empleo del trabajo temporal como medida de flexibilización laboral. Estas diferencias tienen incluso más capacidad explicativa que las discrepancias en las características de la mano de obra y de las empresas instaladas en cada región. Estos resultados cuestionan las medidas adoptadas para combatir el problema de la precariedad laboral en España, al no haber considerado las especificidades regionales.

Alternative Energy Conversion Systems for a Micro Scale Wind Turbine

This Master's thesis deals with a Micro Scale Wind Wind Turbine application. The thesis consists of nine chapters. The first chapter is an introduction to the philosophy of a small scale wind turbine application. The second defines concepts, and lists the requirements. The third presents the whole application for an On-Grid , and for an Off-Grid arrangement, with main concentration on lighting, heating, and energy storage. The fourth deals with the Inverter's technology, which are used for the conversion of the produced power. The fifth chapter presents the available storage technology and it's possibilities. The sixth deals with the system, and the technological means used for the implementation. The seventh presents the PLC device, which was used as the controller for the management of the whole application. The eighth deals with the concept and the control application philosophy that the PLC involves. And the final chapter presents conclusions and ideas for further considerations.

El software libre al servicio de la economía productiva : Caso real de implantación de un ERP en una micro PYME

Este trabajo de fin de grado intenta, mediante el caso real de la implantación de un ERP en una micro PYME, ajustar a la realidad socioeconómica de la gran mayoría de empresas españolas las técnicas de implantación de software y de gestión de proyectos, usando como elemento conductor un ERP de software libre, para conseguir el triple objetivo de mantener los ratios de calidad deseados en cualquier proyecto de ingeniería de software, con unos costes asumibles por una micro PYME y satisfaciendo las necesidades de negocio.

Desenvolvimento de um micro-aquecedor para sistemas de análise química em fluxo: determinação espectrofotométrica de manganês em plantas

In this work a micro-heater device to be used as an integral part of the flow analysis manifold is described. The usefulness of the device was demonstrated using it in the development of a multicommutated flow analysis procedure for the spectrophotometric determination of manganese in plant digest. The method was based on the manganese oxidation by periodate in phosphoric acid medium to form the permanganate anion. The reaction development is dependent on the temperature and it was observed that at 25 °C a time interval of ca. 15 min was necessary for the reaction to attain equilibrium. Setting the temperature to 70 ºC, this time interval could be decreased to ca. 30 s. This condition was easily attained employing the proposed micro-heater device coupled to the manifold. The procedure was applied to manganese determination in soybean digests and results compared with those obtained by inductively coupled argon plasma optical emission spectrometry (ICP-OES). No significant difference at 90% confidence level was observed. A linear response for sample concentrations ranging from 5.0 to 30.00 mg L-1 Mn2+; a relative standard deviation of 1.3% (n = 6) for a typical sample containing 6.3 mg L-1 Mn2+; a sampling rate of 22 determinations per hour; a low reagent consumption, of 12.0 mg NaIO4 per determination; and a detection limit of 1.2 mg L-1 were achieved.

Anisotropic surface properties of micro/nanostructured a-C:H:F thin films with self-assembly applications

The singular properties of hydrogenated amorphous carbon (a-C:H) thin filmsdeposited by pulsed DC plasma enhanced chemical vapor deposition (PECVD), such as hardness and wear resistance, make it suitable as protective coating with low surface energy for self-assembly applications. In this paper, we designed fluorine-containing a-C:H (a-C:H:F) nanostructured surfaces and we characterized them for self-assembly applications. Sub-micron patterns were generated on silicon through laser lithography while contact angle measurements, nanotribometer, atomic force microscopy (AFM), and scanning electron microscopy (SEM) were used to characterize the surface. a-C:H:F properties on lithographied surfaces such as hydrophobicity and friction were improved with the proper relative quantity of CH4 and CHF3 during deposition, resulting in ultrahydrophobic samples and low friction coefficients. Furthermore, these properties were enhanced along the direction of the lithographypatterns (in-plane anisotropy). Finally, self-assembly properties were tested with silicananoparticles, which were successfully assembled in linear arrays following the generated patterns. Among the main applications, these surfaces could be suitable as particle filter selector and cell colony substrate.

Método de estudo da adsorção de triadimenol com micro-colunas de solo e centrifugação

Normally, the determination of equilibrium constants (k d) in batch experiments uses a high solution to soil ratio, which does not represent field conditions. In this study we present an alternative method to evaluate adsorption constants, using micro-columns of soil at higher soil to solution ratios. The centrifugation force and equilibration time were investigated. The triadimenol distribution along the column profile is controlled by diffusion and equilibration times greater than 24 h are needed to achieve reproducibility. The centrifugation force must be superior to 670 g in order to guarantee enough extraction of the liquid solution from the soil columns.

Los determinantes sociales del pensamiento: ni anomalismo ni funcionalización

El principal objetivo del presente trabajo es indagar si las habituales tentativas por descifrarel pensamiento desde un punto de vista sociológico, a pesar de su vehemente compromisoantirreduccionista, podrían aceptar en último término la reducción de ideas, argumentos y doctrinasa sus presuntos determinantes sociales. En una primera etapa analizamos el ¿sociologismoanómalo¿ de Martin Kusch, señalamos algunas de sus lagunas, y establecemos que la panopliaconceptual en losofía de la mente es fértilmente aplicable al ámbito racional-social. A continuaciónconsideramos el funcionalismo reduccionista de Jaegwon Kim, nos centramos en latesis de que los estados intencionales de la mente, al contrario de lo que ocurre con los qualia,son causalmente funcionalizables, e intentamos establecer sus posibles repercusiones en la interpretaciónsocial del pensamiento. La aplicación de la metodología funcionalista al horizonteracional-social, de todos modos, parece venir desmentida por la evidencia, ya que las propiedadesdel pensamiento equiparables a los qualia son de hecho eminentemente funcionalizablesen la medida que fundamentan la efectividad social de los recursos gurativos y retóricos. Enun sentido análogo, la obra de Hans Blumenberg demuestra que los inescrutables ingredientes gurativos de todo pensamiento que él denomina ¿metáforas absolutas¿ son tan decisivos paracualquier proceso abstractivo que los conceptos nunca llegan a agotar su alcance determinador.Con lo cual los conceptos y las ideas más generales, antes considerados del todo funcionalizables,ahora dependen de algunas metáforas básicas, aun cuando por analogía con los qualia selas creía inmunes a toda funcionalización. Por tanto parece que la reducción no puede resolverlas di cultades que plantean los presuntos ¿determinantes sociales del pensamiento¿. Al mismotiempo, y con rmando así algunos emergentismos, los aspectos causal-funcionales del ámbitoracional-social dan la impresión de ser inconciliables con la enigmática estructura causal queponen de mani esto las aproximaciones losó cas al problema mente-cuerpo.

Calidad de vida y sus factores determinantes en universitarios españoles de Ciencias de la Salud

La calidad de vida en la población universitaria adquiere una especial importancia ya que permite obtener información sobre las condiciones de vida de los universitarios y, sobre todo, de cómo éstos las perciben. Objetivo: Evaluar la calidad de vida de los universitarios que cursan estudios en ciencias de la salud y su relación con diferentes factores tales como: hábitos de vida, parámetros antropométricos y la influencia de las distintas variables sobre su percepción. Material y Método: Estudio transversal de una muestra de 1.753 estudiantes de ciencias de la salud de nueve universidades españolas con diseño muestral aleatorio y estatrificado según curso y facultad al que se le aplicó un cuestionaro ad hoc que recogía todas las variables a estudio. Resultados: La calidad de vida percibida por los participantes fue Me = 75. Los factores explorados de la calidad de vida se co-relacionaron significativamente con la percepción global de calidad de vida de los estudiantes (p<0,001). Se establecieron 3 dimensiones y el impacto de cada una de ellas sobre la percepción de calidad de vida global fue p<0,001. Los varones percibieron mejor calidad de vida que las mujeres y también los estudiantes con menor Índice de Masa Corporal (IMC). Conclusión: Los universitarios son una población clave para realizar actividades de promoción y prevención de la salud por lo que resulta necesario crear mejores infraestucturas y recursos educativos para mejorar la CV y fomentar hábitos y estilos de vida saludable con especial atención en la alimentación y la realización de una adecuada actividad física.

Síntese de sulfadiazina e sulfadiazina de prata em escala semi-micro: prática experimental em síntese de fármacos

The total synthesis of sulfadiazine and silver sulfadiazine from readily available starting materials was adapted to semi-micro laboratory scale and is proposed as an experiment in drug synthesis for undergraduate courses.

Preparação de amostra de fígado bovino e estudo de micro homogeneidade para a determinação de Cd E Pb por espectrometria de absorção atômica com atomização eletrotérmica e amostragem direta de sólido

This work describes a systematic study for bovine liver sample preparation for Cd and Pb determination by solid sampling electrothermal atomic absorption spectrometry. Samples were prepared using different procedures: (1) drying in a household microwave oven followed by drying in a stove at 60 ºC until constant mass, and (2) freeze-drying. Ball and cryogenic mills were used for grinding. Particle size, sample size and micro sample homogeneity were investigated. All prepared samples showed good homogeneity (He < 10) even for low sample mass, but samples dried in a microwave oven/stove and ground in a ball mill presented the best homogeneity.