Combinación de sistemas de flujo de baja y alta presion para la determinacion de Mg, Ca y Sr en salmueras por espectrofotometria de absorcion atomica con llama

This article describes the combination of low- and high-pressure flow systems for the determination of Magnesium, Calcium and Strontium by flame atomic absorption spectrometry (FAAS). In the low-pressure system a short C-18 RP column (length 0,5 cm) was utilized for the preconcentration/matrix separation step, xylenol orange was used as chelating agent and tetrabutylamonium acetate for ion pair formation. The hydraulic high pressure nebulization (HHPN) was used for sample transport and sample introduction in the high pressure system. The repeatabilities and detection limits for Mg, Ca and Sr were determined and compared with those obtained by pneumatic nebulization (PN). The results show that the detection limits obtained using the HHPN for Mg, Ca and Sr are between 1.5 to 2 times better than those obtained by PN when the signal transient was measured in area. The system presented a sampling frequency of 130 h-1 for direct determination of Mg, Ca or Sr in samples of saturated sodium chloride used in the production of chlorine and sodium hydroxide.

Los Pronombres átonos (le, la, lo), sus variaciones dialectales y su tratamiento en la clase de ELE

En este trabajo he abordado la enseñanza de los pronombres átonos le, la, lo / les, las, los y sus variantes dialectales en el contexto de la enseñanza de español como lengua extranjera. Las variaciones en el uso de los pronombres, ya no solo en la Península, sino en el resto de países hispanohablantes, son bastante numerosas y es una de las mayores dificultades que presenta el español

En blanc et en noir

Soitinnus : Pianot (2).

Rivolgete a lui lo sguardo

Äänitetty: 7.-8.5.1953, Los Angeles.

Reaction Kinetics and Viscosity Modelling in the Fusion Syntheses of Ca- and Ca/Mg-resinates

Rosin is a natural product from pine forests and it is used as a raw material in resinate syntheses. Resinates are polyvalent metal salts of rosin acids and especially Ca- and Ca/Mg- resinates find wide application in the printing ink industry. In this thesis, analytical methods were applied to increase general knowledge of resinate chemistry and the reaction kinetics was studied in order to model the non linear solution viscosity increase during resinate syntheses by the fusion method. Solution viscosity in toluene is an important quality factor for resinates to be used in printing inks. The concept of critical resinate concentration, c crit, was introduced to define an abrupt change in viscosity dependence on resinate concentration in the solution. The concept was then used to explain the non-inear solution viscosity increase during resinate syntheses. A semi empirical model with two estimated parameters was derived for the viscosity increase on the basis of apparent reaction kinetics. The model was used to control the viscosity and to predict the total reaction time of the resinate process. The kinetic data from the complex reaction media was obtained by acid value titration and by FTIR spectroscopic analyses using a conventional calibration method to measure the resinate concentration and the concentration of free rosin acids. A multivariate calibration method was successfully applied to make partial least square (PLS) models for monitoring acid value and solution viscosity in both mid-infrared (MIR) and near infrared (NIR) regions during the syntheses. The calibration models can be used for on line resinate process monitoring. In kinetic studies, two main reaction steps were observed during the syntheses. First a fast irreversible resination reaction occurs at 235 °C and then a slow thermal decarboxylation of rosin acids starts to take place at 265 °C. Rosin oil is formed during the decarboxylation reaction step causing significant mass loss as the rosin oil evaporates from the system while the viscosity increases to the target level. The mass balance of the syntheses was determined based on the resinate concentration increase during the decarboxylation reaction step. A mechanistic study of the decarboxylation reaction was based on the observation that resinate molecules are partly solvated by rosin acids during the syntheses. Different decarboxylation mechanisms were proposed for the free and solvating rosin acids. The deduced kinetic model supported the analytical data of the syntheses in a wide resinate concentration region, over a wide range of viscosity values and at different reaction temperatures. In addition, the application of the kinetic model to the modified resinate syntheses gave a good fit. A novel synthesis method with the addition of decarboxylated rosin (i.e. rosin oil) to the reaction mixture was introduced. The conversion of rosin acid to resinate was increased to the level necessary to obtain the target viscosity for the product at 235 °C. Due to a lower reaction temperature than in traditional fusion synthesis at 265 °C, thermal decarboxylation is avoided. As a consequence, the mass yield of the resinate syntheses can be increased from ca. 70% to almost 100% by recycling the added rosin oil.

A vueltas con la Crónica del rey don Rodrigo

The paper discusses the problem of the literary genre of the Crónica sarracina from a peninsular and european points of view. It is considerer through the prism of a new kind of fiction, related to history and an incipient realism, which grows up along the 15th century. Moreover, it reveals new fragments inspired by Pedro de Corral from the catalan version of Seneca’s tragedies and from the Libro de los doce sabios

El Cine és de les dones... i dels homes, però això ja ho sabem = El Cine es de las mujeres... y de los hombres, pero eso ya lo sabemos

En aquest monografic dedicat al cine hem recollit articles de directores de dues generacions perque ens expliquin la seva experiencia de fer pel.licules i també hem convidat a un crític perque ens parli, des de la seva diferencia de ser home, del cinema fet per dones

María Zambrano y Georges Bataille: variaciones de lo imposible

[spa]La intención de este artículo es explorar la relación entre poesía, filosofía y el concepto de "lo imposible". Para ello, me propongo revisar no sólo ciertos textos de Zambrano, sino también algunos momentos de la obra de Georges Bataille, en los que estos autores estudiaron, desde dos perspectivas muy distintas, la categoría mencionada.

Socio-Cultural Transformation and the Promotion of Learning

The main premise of Vygotsky’s cultural-historical theory is that to promotelearning, and thus development, educators must intervene in, and change, the students’ socio-cultural context. Vygotsky’s theory, however, has been misinterpreted and the opposite approach has been accepted: the teaching is adapted, according to the context. The result is widespread failure in schools. This article reclaims the true transformative meaning of Vygotskian theory and shows how successful schools in several countries implement various actions to transform their social and cultural environment. Data is presented from six casestudies of successful schools conducted in five European countries. The analysis showsthat these actions improve instrumental learning and, consequently, cognitive development. All these efforts focus on teaching methods that aim to increase the amount that students learn

Jóvenes internados bajo la LO 5/2000 reguladora de la responsabilidad penal del menor. Estudio de casos

This research focuses on life trajectories and desistance from crime processes in a case-study qualitative sample of six offenders from 18 to 21 years old sentenced to penal custody in Barcelona, Spain.The theoretical framework comprises systemism (Mario Bunge, 2000, 2006), the life-course perspective (Elder, 1994, 2007), transition to adulthood (Casal et al., 2006) and desistance from crime as a process (Maruna, 2001; Sampson and Laub, 2003; Bottoms and Shapland, 2010; Cid and Martí, 2011).Information was collected through in-depth personal interviews and analysed through content analysis. Results show the importance of attachment to family and school institutions, as well as an effective professional training skill programme at the correctional facility to achieve a law-abiding lifestyle at adulthood.

Desenvolupament d'un joc per torns parametritzable amb possibilitat multijugador i I.A.

Els jocs són una de les indústries de software més gran del món de la informàtica. Des dels primers jocs en blanc i negre que simulaven raquetes i una pilota, fins avui en dia, en que el desenvolupament d’un joc porta darrere un equip de professionals tant o més gran que el major dels projectes informàtics del món de les indústries, els jocs han evolucionat més que la majoria de programes. La possibilitat d’elaborar un joc és, a part d’una proposta temptadora (ja que difereix enormement de qualsevol pràctica feta durant la carrera), un repte de caire personal per algú que sempre ha estat en contacte amb videojocs i que, després d’adquirir una sèrie de coneixements indispensables, s’ha proposat d’intentar desenvolupar-ne un des de l’arrel. L’objectiu d’aquest treball és doncs això, aprendre com neix un joc partint de res, i veure totes les complicacions que sorgeixen a l’hora de desenvolupar-lo. Els resultats delt projecte mostren generosament el gran nombre de problemes que sorgeixen en un procés com aquest, però com a conclusions importants cal destacar la satisfacció envers els resultats obtinguts, així com els coneixements que s’han guanyat mitjançant el desenvolupament del programa.

epiCentre!: rehabilitació de Ca n'Oliver com a centre d'art

Award-winning

Justicia y ciencia. Uniendo lo mejor de ambos mundos

La justicia y la ciencia son ámbitos muy diferentes de la actividad humana. Sin embargo, los conocimientos científicos dan lugar a la aparición de una serie de disciplinas aplicadas que son de gran utilidad en forensia y que pueden ser trascendentales en la Administración de la Justicia. El problema es reconocer primero si una especialidad es realmente científica y si puede utilizarse de manera fiable en el ámbito de la justicia. En este sentido, la utilización de las pruebas de ADN es un buen ejemplo de cómo, poco a poco, se ha ido ajustando su uso en los tribunales. Además los laboratorios donde se practican esas técnicas forenses están correctamente homologados y al mismo tiempo los especialistas que trabajan en ellos son profesionales con una sólida formación y que se mantienen constantemente al día. Otro elemento crucial es que los expertos que aportan su testimonio deben hacerlo de manera precisa y comprensible. En los casos en que se presente una prueba pericial basada en una aproximación científica novedosa, ésta debe cumplir toda una serie de requisitos para poder ser aceptada por los tribunales.

Magnetic Perovskites Sr2FeMoO6 and La(1-x)Ca(x)MnO3: Synthesis, Fabrication and Characterization of Nanosized Powders and Thin Films

Due to font problem on the tilte field the titlte of the thesis is corrected here. The title of the thesis is: Magnetic Perovskites Sr₂FeMoO₆ and La_(1-x)Ca<sub>(x)MnO₃: Synthesis, Fabrication and Characterization of Nanosized Powders and Thin Films