Propiedades de fusión de algunos lípidos estructurados procedentes del aceite de soja con alto contenido en ácido esteárico

A number of structured lipids native to high stearic acid soybean oil were synthesized and their physical properties were determined by pulsed nuclear magnetic resonance (NMR), Mettler dropping point and differential scanning calorimetry (DSC). 1,3 Distearo-2-olein (SOS), 1,3 distearo-2-linolein (SLS) and1,3 distearo-2-linolenin (SlnS) were synthesized from pure 1,3 diacylglycerols and the appropriate fatty acid. Pulsed NMR determinations over the temperature range 10-50 ºC showed that the symmetrical triacylglycerols (SUS: where S = stearic, U = oleic, linoleic or linolenic) are high and sharply melting materials, all showing substantial amounts of solids at temperatures up to 33.3 ºC, yet are completely melted at only a few degrees higher. Mettler dropping points for SOS, SLS and SlnS were 44.1, 37.9 and 36.5 ºC respectively. The heats of fusion for the structured triacylglycerols were determined by DSC and shown to be of the order 29-32 cal/gm compared to 45 cal/gm for SSS. The heats of fusion were also calculated from Mettler dropping point determinations as admixtures with soybean oil and showed consistent agreement with the DSC data.Se sintetizaron algunos lípidos estructurados procedentes del aceite de soja con alto contenido en ácido esteárico y sus propiedades físicas se determinaron por resonancia magnética nuclear pulsada (NMR), punto de goteo Mettler y calorimetría diferencial de barrido (DSC). Se sintetizaron 1,3 diestearo-2-oleina (SOS), 1,3 diestearo-2-linoleina (SLS) y 1,3 diestearo-2-linolenina (SlnS) a partir de 1,3 diacilgliceroles y de los ácidos grasos adecuados puros. Las determinaciones de NMR pulsada en el rango de temperaturas 10- 50 ºC mostraron que los triacilgliceroles simétricos (SUS: donde S = esteárico, U = oleico, linoleico o linolénico) funden a mayor temperatura y más bruscamente, todos presentan altos contenidos en sólidos a todas las temperaturas hasta los 33.3 ºC, estando completamente fundidos a sólo unos pocos grados por encima. Los puntos fusión Mettler de SOS, SLS y SlnS fueron 44.1, 37.9 y 36.5 ºC respectivamente. Los calores de fusión de los triacilgliceroles estructurados determinados por DSC resultaron del orden de 29-32 cal/gm frente a 45 cal/gm del SSS. Se calcularon los calores de fusión también mediante las determinaciones de los puntos de goteo Mettler como mezclas con aceite de soja y mostraron una buena concordancia con los datos DSC

Constraining top squark in R-parity violating SUSY model using existing Tevatron data

Signal of lighter top squark has been looked for using Tevatron data in the di-electron plus di-jet channel. We find that the mass of the lighter top squark when it decays dominantly in the electron plus jet channel, can be ruled out up to 220 GeV at 95% C.L. using di-electron data. In the framework of R-parity breaking SUSY model we exclude relevant R-parity violating couplings for a range of top squark masses and other SUSY parameters. The bounds on R-parity violating couplings are very stringent for the parameter space where lighter top squark turns out to be the next to lightest supersymmetric particle.Comment: 12 pages, 4 Figures, LateX, minor changes, few references added, version to appear in Physical Rev.

Predictors of reading literacy for first and second language learners

In this study an attempt was made to construct a multi-factor model predicting the development of reading literacy in the upper grades of primary school in the Netherlands for subgroups of 729 first language (L1) learners and 93 second language (L2) learners. Following a longitudinal design, it was explored to what extent the variation in reading literacy development in L1 and L2 from grade 4 to grade 6 can be explained from children’s word decoding, language, mathematics and nonverbal reasoning skills, reading motivation and self confidence as well as their home reading resources. The results showed that L1 and L2 learners differed in reading literacy skills, language, mathematics, and reasoning skills. Structural equation modelling showed that the reading literacy development in both L1 and L2 learners could be explained from decoding, language, mathematics and reasoning skills, as well as their motivation and self-confidence. A striking difference was the fact that home reading resources had an impact on reading literacy in L1 learners but not in L2 learners

To what extent do frameworks of reading development and the phonics screening check support the assessment of reading development in England?

The purpose of this article is to question the suitability of the phonics screening check in relation to models and theories of reading development. The article questions the appropriateness of the check by drawing on theoretical frameworks which underpin typical reading development. I examine the Simple View of Reading developed by Gough and Tunmer and Ehri’s model of reading development. The article argues that the assessment of children’s development in reading should be underpinned and informed by a developmental framework which identifies the sequential skills in reading development