Estudio de imanes moleculares de Co(ii): desde sistemas aislados hasta sistemas organizados y multifuncionales

Dentro de la disciplina conocida como Magnetismo Molecular, y a raíz del descubrimiento del Mn12 en 1993, ha surgido un gran interés por las moléculas que presentan una lenta relajación de la magnetización por debajo de una temperatura de bloqueo. A estas moléculas se les conoce como Imanes Unimoleculares (Single Molecule Magnets, SMMs). En la última década, la utilización de compuestos con un único centro metálico paramagnético (Single Ion Magnets, SIMs) se ha postulado como una de las nuevas estrategias utilizadas para la obtención de compuestos que presentan lenta relajación de la magnetización con barreras efectivas más elevadas. Además, desde un punto de vista experimental y teórico, los SIMs constituyen el modelo más simple para el estudio y comprensión de los fenómenos de lenta relajación de la magnetización y túnel cuántico. Debido a todas estas razones, en esta Tesis Doctoral hemos focalizado nuestro interés en el estudio y la comprensión de, principalmente, compuestos mononucleares de CoII que presentan un comportamiento de molécula imán, aprovechando la inherente anisotropía magnética del ion CoII de espín alto (S = 3/2) y reforzándola con la utilización de ligandos que conduzcan a simetrías altamente distorsionadas. Así pues, estas geometrías podrán conducirnos a compuestos con grandes valores de la anisotropía magnética axial. Los resultados obtenidos en este trabajo se han agrupado en cinco capítulos: (i) Un primer capítulo que se centra en el estudio magneto-estructural de compuestos mononucleares de CoII en una simetría octaédrica. Estos compuestos nos permitirán analizar cómo afectan los cambios electrónicos y estructurales a los parámetros que determinan la anisotropía magnética e, indirectamente, al comportamiento de molécula imán. (ii) Un segundo capítulo que se centra en el análisis de compuestos de CoII con un índice de coordinación más bajo, donde el efecto del campo de los ligandos es menor y puede ser determinante en la modulación de la anisotropía magnética axial. De ese modo completamos el estudio magneto-estructural desarrollado en el primer capítulo. (iii) Un tercer capítulo donde se desarrolla una nueva estrategia de síntesis de materiales que pueden actuar como sensores químicos o “interruptores” magnéticos. En este capítulo se presenta una pareja de complejos de coordinación de CoII capaces de exhibir y modificar los efectos de lenta relajación de la magnetización al modularse su entorno de coordinación. (iv) Un cuarto capítulo en el que, utilizando los conocimientos obtenidos en el estudio de los complejos mononucleares, se han diseñado y estudiado compuestos dinucleares de CoII débilmente conectados electrónicamente. Estos compuestos se encuentran unidos mediante un ligando puente de tipo carboxilato, manteniendo su comportamiento de SIM, y pudiendo comportarse como 2-qubits QG. (v) Un quinto y último capítulo en el que se ha preparado y caracterizado una nueva familia de compuestos en la que se han conjugado dos propiedades; la alta porosidad y el comportamiento de SIM, dando lugar a una nueva familia de SIM-MOFs donde el comportamiento de SIM está modulado por la naturaleza del huésped alojado en sus poros.In the discipline known as Molecular Magnetism, and following the disclosure of Mn12 in 1993, has awakened a great interest in molecules that shows slow relaxation effects of the magnetization below a blocking temperature (TB). These molecules are known as Single Molecule Magnets (SMMs). During the last decade, mononuclear complexes with a single slow-relaxing metal centre, the so-called Single Ion Magnets (SIMs), has been used as a new strategy to obtain metal complexes with larger energy barriers. These compounds have emerged as the simplest model systems for fundamental research on magnetic relaxation dynamics and tunnelling effects from both the experimental and theoretical points of view. For all these reasons, in this Thesis, we have focused on the study and comprehension of CoII complexes that show slow magnetic relaxation behaviour, making the most of the inherent anisotropy of the high-spin CoII ion (S = 3/2). In addition, the CoII complexes have been designed with ligands that impose a high-distorted symmetry. Hence, these geometries can lead us to metal complexes with large axial-magnetic anisotropy values. The results obtained in this work has been arranged in five chapters: (i) The first chapter focus on the study of mononuclear CoII complexes with an octahedral symmetry. These compounds allow us to analyse how the electronic and structural changes affect the magnetic anisotropy parameters and, indirectly, the slow magnetic relaxation effects. (ii) The second chapter deals with the analysis of CoII complexes with a lower coordination index, where there is a lesser effect of the ligand field. These geometrical parameters can be decisive in the axial-magnetic anisotropy. In this way, the magneto-structural study developed in the first chapter is concluded. (iii) The third chapter expands a new strategy to synthesise materials that are able to act as chemical sensors or magnetic switches. To achieve this, we have used a couple of mononuclear complexes that modulate their coordination sphere by a reversible hydration/dehydration process, being only one of them capable of showing slow magnetic relaxation behaviour when the coordination environment is modulated. (iv) In the fourth chapter, we have used the acquired knowledge of mononuclear compounds of chapter II to design polynuclear systems: dinuclear compounds with CoII weakly electronically connected by carboxylate ligands. The choice of the selected bridge, i.e. carboxylate-based ligand, exploit the possibility of keeping their SIM behaviour and being able to behave as a 2-qubits QG. (v) The fifth and last chapter shows a new family of compounds that combines together two properties; the high porosity and the SIM behaviour, leading to a new SIM-MOFs family where the chemical nature of the hosted molecules in its pores modulates the SIM behaviour

Libertad de expresión, redes sociales y modernidad

El artículo estudia la libertad de expresión en las redes sociales. La naturaleza de la libertad de pensamiento y expresión en el sistema moderno digital, el desarrollo de su privatización por el dominio y control de las corporaciones digitales. Se destaca la libertad de expresión como un proceso conflictivo entre la «barbarie cultural» y las respuestas colaborativas en las redes ciudadanas. El futuro de la libertad de expresión pasa por considerar el divorcio entre el poder mundializado de Internet y las actuaciones locales fragmentadas, pero, sobre todo, por la disputa entre el mercado corporativo, los Estados y la sociedad civil mundial. Palabras clave: Libertad de expresión, redes sociales, modernidad, gobierno digital, cultura de la elección.   Abstract This paper study the freedom of expression in social media platforms. The nature of freedom of thought and expression in the modern digital system, the development of its privatization by he dominance and control of digital corporations. It highlights freedom of expression as a conflictive process between “cultural barbarism” and collaborative responses in social media. The future of freedom of expression involves considering the divorce between the globalized power internet and the fragmented local actions, but above all, over the dispute between the corporate market, the states and global civil society. Keywords: Freedom of expression, social networks, modernity, digital government, choice cultur

The parasitic travel of Margaritifera margaritifera in Atlantic salmon gills: from glochidium to post-larva

The larval development of the endangered freshwater mussel Margaritifera margaritifera (L.) represents one of the most unique parasitism among naiads, in which larva parasite the fish gills for several months. Despite the importance of this parasitic phase to successfully culture the freshwater mussel, the larval morphogenesis remains understudied. To describe the parasitic larval development and metamorphosis, Atlantic salmon (Salmo salar L.) were exposed to glochidia, sampled periodically to visualize the gills by stereomicroscopy and light microscopy and results were summarized throughout three developmental stages. Once attached to the fish gills, glochidia changed their morphology within the first days and acquired an intermediate stage termed mushroom larva due to the presence of the mushroom body and the zip membrane, both structures are transitory and distinctive of this long-lasting parasitism. The zip membrane, located at the valve cleft, may play a unique role in the isolation and acquisition of non-particulate nutrients from the fish, while the mushroom body of the mantle accumulates abundant intracytoplasmic lipid droplets. After 200 days, a successful metamorphosis was evidenced by the formation of a complete set of post-larval organs, pointing to the acquisition of different functionality, which will be essential for the settlement and deposit-feeding into the riverbed. Among the post-larval organs, the byssal complex of the post-larval foot was described for the first time at the end of the parasitic stage of naiads. In conclusion, this study provides an overview of the larval morphogenesis of M. margaritifera, from glochidium to post-larva, essential for understanding the parasitic interaction between the freshwater mussel larva and the fish host. Moreover, the morphological techniques and the hallmarks described might be applicable to optimize and monitor the larval developmental status during one of the most critical stages of the captive breeding programmes of endangered freshwater musselsS

Applying genomic approaches to delineate conservation strategies using the freshwater mussel Margaritifera margaritifera in the Iberian Peninsula as a model

Effective conservation actions to counteract the current decline of populations and species require a deep knowledge on their genetic structure. We used Single Nucleotide Polymorphisms (SNPs) to infer the population structure of the highly threatened freshwater pearl mussel Margaritifera margaritifera in the Iberian Peninsula. A total of 130 individuals were collected from 26 locations belonging to 16 basins. We obtained 31,692 SNPs through Genotyping by Sequencing (GBS) and used this dataset to infer population structure. Genetic diversity given as observed heterozygosity was low. Pairwise FST comparisons revealed low levels of genetic differentiation among geographically close populations. Up to 3 major genetic lineages were determined: Atlantic, Cantabrian and Douro. This structure suggests a close co-evolutionary process with brown trout (Salmo trutta), the primordial fish host of this mussel in the studied area. Some sub-basins showed some genetic structuring, whereas in others no intrapopulation differentiation was found. Our results confirm that genetic conservation units do not match individual basins, and that knowledge about the genetic structure is necessary before planning recovery plans that may involve relocation or restocking. The same reasoning should be applied to strictly freshwater species that are sessile or have restricted dispersal abilities and are currently imperiled worldwide.This work was supported by national funds of the Portuguese Foundation for Science and Technology (FCT) through the project MUSSELFLOW (contract PTDC/BIA- EVL/29199/2017) and under the strategic project LA/P/0069/2020 granted to the Associate Laboratory ARNET; and the grant awarded to C.S. Lima (MARE-ISPA/BI/004/2015).Peer reviewe

Research priorities for freshwater mussel conservation assessment

Freshwater mussels are declining globally, and effective conservation requires prioritizing research and actions to identify and mitigate threats impacting mussel species. Conservation priorities vary widely, ranging from preventing imminent extinction to maintaining abundant populations. Here, we develop a portfolio of priority research topics for freshwater mussel conservation assessment. To address these topics, we group research priorities into two categories: intrinsic or extrinsic factors. Intrinsic factors are indicators of organismal or population status, while extrinsic factors encompass environmental variables and threats. An understanding of intrinsic factors is useful in monitoring, and of extrinsic factors are important to understand ongoing and potential impacts on conservation status. This dual approach can guide conservation status assessments prior to the establishment of priority species and implementation of conservation management actions.NF-R was supported by a post-doctoral fellowship (Xunta de Galicia Plan I2C 2017-2020, 09.40.561B.444.0) from the government of the autonomous community of Galicia. BY was supported by the Ministry of Science and Higher Education (no. 0409-2016-0022). DLS was supported by the G. E. Hutchinson Chair at the Cary Institute of Ecosystem Studies. AO was supported by the Russian Foundation for Basic Research (no. 17-44-290016). SV was funded by European Investment Funds by FEDER/COMPETE/POCI- Operacional Competitiveness and Internacionalization Programme, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT-Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013. NF-R is very grateful to the University of Oklahoma Biological Survey for providing space to work in the U.S. and especially to Vaughn Lab members. Authors are very grateful to Akimasa Hattori, Allan K. Smith, Andrew Roberts, Daniel Graf, David Stagliano, David T. Zanatta, Dirk Van Damme, Ekaterina Konopleva, Emilie Blevins, Ethan Nedeau, Frankie Thielen, Gregory Cope, Heinrich Vicentini, Hugh Jones, Htilya Sereflisan, Ilya Vikhrev, John Pfeiffer, Karen Mock, Mary Seddon, Katharina Stockl, Katarzyna Zajac, Kengo Ito, Marie Capoulade, Marko Kangas, Michael Lange, Mike Davis, Pirkko-Liisa Luhta, Sarina Jepsen, Somsak Panha, Stephen McMurray, G. Thomas Watters, Wendell R. Haag, and Yoko Inui for their valuable contribution in the initial selection and description of extrinsic and intrinsic factors. We also wish to thank Dr. Amanda Bates, Chase Smith, and two anonymous reviewers for comments on earlier drafts of this manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government

El oficio de mujer en la pequeña nobleza urbana del siglo XVII español

Este artículo es una sucinta mirada retrospectiva a través de tres siglos hacia las funciones que desempeñaban las mujeres de la pequeña nobleza urbana del Seiscientos que permanecían «en el siglo» y seguían el camino del matrimonio. Su intención es analizar los tres roles que se les asignaban convencionalmente y mostrar cómo no siempre constreñían su acción a los estrechos límites establecidos por el sistema social. El punto de partida de nuestro trabajo son los datos proporcionados por una fuente que, tratada con el cuidado que exigen los documentos literarios, resulta de extraordinario valor: la novela barroca. Este género literario ha recibido por nuestra parte una atención que se ha visto compensada con creces por la información que ha aportado a nuestra memoria de licenciatura, en la que tratamos entre otros muchos temas el que nos ocupa en el presente artículo

2014, année de la Stratocaster !

National audienc