Studies on the interaction of surfactants and neutral cyclodextrins by capillary electrophoresis. Application to chiral analysis

In the present study, mixed systems composed of SDS in the presence of neutral cyclodextrins were considered. Firstly, the effect of the CDs on the CMC of the surfactant was evaluated by CE experiments. Furthermore, a new CE approach based on electric current measurement was developed for the estimation of the stoichiometry as well as of the binding constants of SDS-CDs complexes. The results of these investigations were compared to those obtained with a different technique, electronic paramagnetic resonance (EPR). The obtained results suggested that methylated CDs, in particular (2,6-di-O-methyl)-beta-cyclodextrin (DM-beta-CD), strongly affect the micellization of SDS in comparison to the other studied CDs. This effect also paralleled the chiral CD-MEKC performance, as indicated by the enantioresolution of (+/-)-Catechin, which was firstly selected as a model compound representative of important chiral phytomarkers. Then a CD-MEKC system, composed of sodium dodecyl sulfate as surfactant (90 mM) and hydroxypropyl-beta-cyclodextrin (25 mM) as chiral selector, under acidic conditions (25 mM borate – phosphate buffer, pH 2.5) was applied to study the thermal epimerisation of epi-structured catechins, (-)-Epicatechin and (-)-Epigallocatechin, to non epi-structured (-)-Catechin and (-)-Gallocatechin. The latter compounds, being non-native molecules, were for the first time regarded as useful phytomarkers of tea sample degradation. The proposed method was applied to the analysis of more than twenty tea samples of different geographical origins (China, Japan, Ceylon), having undergone different storage conditions and manufacturing processes.

Catálogo y estudio de las gramáticas de italiano para hispanohablantes: siglos XVIII y XIX

El objetivo de la presente investigación, el catálogo y estudio de las gramáticas de italiano destinadas a hispanohablantes de los siglos XVIII y XIX, se encuadra en el macrosector gramaticográfico de la historiografía lingüística, en el cual el estudio de las gramáticas de las lenguas dirigidas a hablantes nativos y a hablantes extranjeros, con los consiguientes cruces y trasvases de tradiciones gramaticales, es de significativo interés como destacan: (i) las tesis doctorales defendidas en los últimos quince años; (ii) los proyectos de investigación dirigidos y coordinados por prestigiosos estudiosos del sector; (iii) los congresos organizados para destacar y compartir las principales actualizaciones en torno a los estudios gramaticográficos; y (iv) las publicaciones que surgen de los tres puntos anteriores. El estudio presenta dos partes centrales: la primera (constituida por los capítulos 2 y 3) es la de catálogo y estudio de las diecinueve gramáticas que conforman el corpus en base a ocho áreas descriptivas (1. información catalográfica, 2. autor, 3. editor, 4. hiperestructura, 5. elementos peritextuales, gramaticales y didácticos, 6. variedad de textos y su secuencia didáctica, 7. caracterización, fuentes e influencias, y 8. localización); la segunda (capítulo 4) es la de estudio gramaticográfico de conjunto de los datos más relevantes de las areas de estudio utilizadas en las dos primeras partes. De este modo, daremos un panorama de conjunto sobre (i) la cronología de las obras y sus ediciones y rempresiones; (ii) la nacionalidad, profesión, condición religiosa, etc. de autores; (iii) la geografía de ediciones y editores; (iv) la descripción hiperestructural de las obras; (v) la estructura de los elementos peritextuales; (vi) las partes gramaticales y elementos que las componen; (vii) el verbo: definiciones y paradigma verbal; (vii) los elementos didácticos; (viii) las líneas de descripción gramatical; (ix) la localización de las gramáticas en las bibliotecas españolas.

Analysis of cumulative effects of multiple stressors on saltmarshes and consideration of management options

Natural systems face pressures exerted by natural physical-chemical forcings and a myriad of co-occurring human stressors that may interact to cause larger than expected effects, thereby presenting a challenge to ecosystem management. This thesis aimed to develop new information that can contribute to reduce the existing knowledge gaps hampering the holistic management of multiple stressors. I undertook a review of the state-of-the-art methods to detect, quantify and predict stressor interactions, identifying techniques that could be applied in this thesis research. Then, I conducted a systematic review of saltmarsh multiple stressor studies in conjunction with a multiple stressor mapping exercise for the study system in order to infer potential important synergistic stressor interactions. This analysis identified key stressors that are affecting the study system, but also pointed to data gaps in terms of driver and pressure data and raised issues for potentially overlooked stressors. Using field mesocosms, I explored how a local stressor (nutrient availability) affects the responses of saltmarsh vegetation to a global stressor (increased inundation) in different soil types. Results indicate that saltmarsh vegetation would be more drastically affected by increased inundation in low than in medium organic matter soils, and especially in estuaries already under high nutrient availability. In another field experiment, I examined the challenges of managing co-occurring and potentially interacting local stressors on saltmarsh vegetation: recreational trampling and smothering by deposition of excess macroalgal wrack due to high nutrient loads. Trampling and wrack prevention had interacting effects, causing non-linear responses of the vegetation to simulated management of these stressors, such that vegetation recovered only in those treatments simulating the combined prevention of both stressors. During this research I detected, using molecular genetic methods, a widespread presence of S. anglica (and to a lesser extent S. townsendii), two previously unrecorded non-native Spartinas in the study areas.