Diseño y síntesis de nuevos compuestos aromáticos derivados del pireno, del antraceno y del trifenileno

En este proyecto de tesis se diseñaron y sintetizaron nuevos compuestos aromáticos de interés en ciencia de materiales y química sobre superficie. Se emplearon métodos de síntesis en disolución como las reacciones de cicloadición de arinos o los acoplamientos cruzados catalizados por complejos de metales de transición para obtener derivados extendidos del pireno, del antraceno y del trifenileno. Los compuestos más significativos serán estudiados sobre superficie por colaboradores científicos

Intramolecular coupling of terminal alkynes by atom manipulation

Glaser-like coupling of terminal alkynes by thermal activation is extensively used in on-surface chemistry. Here we demonstrate an intramolecular version of this reaction performed by atom manipulation. We used voltage pulses from the tip to trigger a Glaser-like coupling between terminal alkyne carbons within a custom synthesized precursor molecule adsorbed on bilayer NaCl on Cu(111). Different conformations of the precursor molecule and the product were characterized by molecular structure elucidation with atomic force microscopy and orbital density mapping with scanning tunneling microscopy, accompanied by density functional theory calculations. We revealed partially dehydrogenated intermediates providing insight into the reaction pathway

Hipertermia asociada a dexmedetomidina

Dexmedetomidine is an α2 agonist drug used as an anxiolytic and sedative in patients in Intensive Care Units (ICU) and Resuscitation Units (REA). Its most frequent adverse effects are bradycardia and hypotension, but given the increasing use of this drug, hyperthermia refractory to antipyretic therapy has been discovered. Its diagnosis is one of exclusion after ruling out other possible etiologies of hyperthermia such as infections, drugs...etc. With this clinical case, we want to promote the study of the prevalence, risk factors and triggers of this adverse effect.  La dexmedetomidina es un fármaco α2 agonista utilizado como ansiolítico y sedante en pacientes en Unidad de Cuidados Intensivos (UCI) y Unidades de Reanimación (REA). Sus efectos adversos más frecuentes son bradicardia e hipotensión, pero dado el creciente uso de este fármaco se ha descubierto la hipertermia refractaria a terapia antipirética. Su diagnóstico es de exclusión tras descartar otras posibles etiologías de hipertermia tales como infecciones, fármacos…etc. Con este caso clínico, se quiere promover el estudio de la prevalencia, factores de riesgo y factores desencadenantes de este efecto adverso

Stabilizing edge fluorination in graphene nanoribbons

The on-surface synthesis of edge-functionalized graphene nanoribbons (GNRs) is challenged by the stability of the functional groups throughout the thermal reaction steps of the synthetic pathway. Edge fluorination is a particularly critical case in which the interaction with the catalytic substrate and intermediate products can induce the complete cleavage of the otherwise strong C-F bonds before the formation of the GNR. Here, we demonstrate how a rational design of the precursor can stabilize the functional group, enabling the synthesis of edge-fluorinated GNRs. The survival of the functionalization is demonstrated by tracking the structural and chemical transformations occurring at each reaction step with complementary X-ray photoelectron spectroscopy and scanning tunneling microscopy measurements. In contrast to previous attempts, we find that the C-F bond survives the cyclodehydrogenation of the intermediate polymers, leaving a thermal window where GNRs withhold more than 80% of the fluorine atoms. We attribute this enhanced stability of the C-F bond to the particular structure of our precursor, which prevents the cleavage of the C-F bond by avoiding interaction with the residual hydrogen originated in the cyclodehydrogenation. This structural protection of the linking bond could be implemented in the synthesis of other sp2-functionalized GNRs

Brote de rabia urbana transmitida por perros en el distrito de Santa Marta, Colombia, 2006-2008

Introduction. An urban rabies outbreak occurred in the District of Santa Marta between April 2006 and January 2008, which resulted in the deaths of 4 humans and 28 dogs.Objectives. Three objectives were entertained—first, the diagnostic laboratory techniques were described as well as the rabies control actions taken; second, the impact of anti-rabies dog vaccination was assessed in terms of neutralizing antibody seroconversion; and third, the epidemiological significance and public health implications of the outbreak were examined.Materials and methods. Rabies diagnosis was achieved by direct immunofluorescence, inoculation of mice and immunohistochemistry. Typing of the virus was achieved by indirect immunofluorescence. Control activities included a dog population census, vaccination and treatments for persons exposed to rabies, mass vaccination of dogs and cats, and initiation of a community education program. Seroconversion was investigated by capture ELISA.Results. Antigenic variant 1 was detected in all cases. Of vaccinated dogs, 77% were seropositive,and 47% were seroprotected against rabies. No differences were found in the humoral response between dog gender; however significant differences in dog seroprotection were discovered between localized comunities in Santa Marta.Conclusions. The 2006-2008 urban rabies outbreak was the largest reported in a city in Colombia. It was caused by rabid dogs, and demonstrated that these animals are still a threat for human health despite the existence of efficient rabies vaccines. The control of the outbreak was achieved 20 months after the first rabies case in dogs, and 14 months after the initiation of the first mass vaccination of animals. The necessity of implementation and maintenance of rabies control strategies is underlined for minimizing human risk.Introducción. En el distrito de Santa Marta ocurrió un brote de rabia urbana entre abril de 2006 y enero de 2008, con cuatro casos fatales en humanos y 28 en perros.Objetivos. Describir el brote, las técnicas de diagnóstico de laboratorio y las acciones de control de foco empleadas. Medir el impacto de la vacunación antirrábica canina en términos de seroconversión de anticuerpos neutralizantes. Discutir el significado epidemiológico y las implicaciones en salud pública.Materiales y métodos. Los casos se diagnosticaron por inmunofluorescencia directa, prueba biológica en ratón e inmunohistoquímica. La tipificación viral se hizo por inmunofluorescencia indirecta. Las acciones de control consistieron en un censo canino, vacunación y tratamientos antirrábicos a la población expuesta, vacunación canina y felina, y educación comunitaria. La seroconversión fue investigada por medio de la prueba ELISA de captura.Resultados. La variante antigénica 1 se caracterizó en todos los casos. Se observó seropositividad en 77% de los perros vacunados y protección serológica contra la rabia, en 47%. No se observaron diferencias de la respuesta humoral entre sexos de los perros, pero sí existieron diferencias de los porcentajes de perros protegidos entre las comunas del distrito.Conclusiones. Este brote de rabia ha sido el de mayor magnitud en una ciudad colombiana, según los datos oficiales. Fue causado por perros, lo cual reitera la amenaza que aún representa la rabia urbana para la salud pública, a pesar de la existencia de vacunas eficientes.El control del brote se logró 20 meses después del primer caso en perros y 14 meses después de haberse iniciado la primera vacunación masiva en animales. Es necesario implementar y mantener acciones para el control de la rabia urbana y evitar su impacto en los humanos

Challenges in the synthesis of corannulene-based non-planar nanographenes on Au(111) surfaces

The on-surface synthesis of non-planar nanographenes is a challenging task. Herein, with the aid of bond-resolving scanning tunneling microscopy (BRSTM) and density functional theory (DFT) calculations, we present a systematic study aiming at the fabrication of corannulene-based nanographenes via intramolecular cyclodehydrogenation on a Au(111) surface. The formation of non-planar targeted products is confirmed to be energetically unfavorable compared to the formation of planar/quasi-planar undesired competing monomer products. In addition, the activation of intermolecular coupling further inhibits the formation of the final targeted product. Although it was not possible to access the corannulene moiety by means of on-surface synthesis, partial cyclodehydrogenation of the molecular precursors was demonstrated.This work was financially supported by the Spanish Agencia Estatal de Investigacion (PID2019-107338RB-C62, PID2019-107338RB-C63, PID2019-110037GB-I00 and MAT2016-78293-C6; AEI/FEDER, UE), the Basque Government (IT-1255-19), the European Union’s Horizon 2020 Program (Grant No. 863098), the Xunta de Galicia (Centro singular de investigacion de Galicia accreditation 2019–2022, ED431G 2019/03), the European Union (European Regional Development Fund-ERDF), and European Union’s Horizon 2020 Research and Innovation Programme under the project MEMO (Grant No. 766864).Peer reviewe

Habitat Fragmentation can Modulate Drought Effects on the Plant-soil-microbial System in Mediterranean Holm Oak (Quercus ilex) Forests

© 2015, Springer Science+Business Media New York. Ecological transformations derived from habitat fragmentation have led to increased threats to above-ground biodiversity. However, the impacts of forest fragmentation on soils and their microbial communities are not well understood. We examined the effects of contrasting fragment sizes on the structure and functioning of soil microbial communities from holm oak forest patches in two bioclimatically different regions of Spain. We used a microcosm approach to simulate the annual summer drought cycle and first autumn rainfall (rewetting), evaluating the functional response of a plant-soil-microbial system. Forest fragment size had a significant effect on physicochemical characteristics and microbial functioning of soils, although the diversity and structure of microbial communities were not affected. The response of our plant-soil-microbial systems to drought was strongly modulated by the bioclimatic conditions and the fragment size from where the soils were obtained. Decreasing fragment size modulated the effects of drought by improving local environmental conditions with higher water and nutrient availability. However, this modulation was stronger for plant-soil-microbial systems built with soils from the northern region (colder and wetter) than for those built with soils from the southern region (warmer and drier) suggesting that the responsiveness of the soil-plant-microbial system to habitat fragmentation was strongly dependent on both the physicochemical characteristics of soils and the historical adaptation of soil microbial communities to specific bioclimatic conditions. This interaction challenges our understanding of future global change scenarios in Mediterranean ecosystems involving drier conditions and increased frequency of forest fragmentation

Intramolecular Coupling of Terminal Alkynes by Atom Manipulation

Glaser‐like coupling of terminal alkynes by thermal activation is extensively used in on‐surface chemistry. Here we demonstrate an intramolecular version of this reaction performed by atom manipulation. We used voltage pulses from the tip to trigger a Glaser‐like coupling between terminal alkyne carbons within a custom‐synthesized precursor molecule adsorbed on bilayer NaCl on Cu(111). Different conformations of the precursor molecule and the product were characterized by molecular structure elucidation with atomic force microscopy and orbital density mapping with scanning tunneling microscopy, accompanied by density functional theory calculations. We revealed partially dehydrogenated intermediates, providing insight into the reaction pathwayWe thank the European Union (Project SPRING, contract no. 863098), the ERC grant AMSEL (682144), the Spanish Agencia Estatal de Investigación (MAT2016-78293-C6-3-R and CTQ2016-78157-R), Xunta de Galicia (Centro de Investigación de Galicia accreditation 2019–2022, ED431G 2019/03) and the EuropeanRegional Development Fund-ERDF for financial supportS

On-surface synthesis and collective spin excitations of a triangulene-based nanostar

Triangulene nanographenes are open-shell molecules with predicted high spin state due to the frustration of their conjugated network. Their long-sought synthesis became recently possible over a metal surface. Here, we present a macrocycle formed by six [3]triangulenes, which was obtained by combining the solution synthesis of a dimethylphenyl-anthracene cyclic hexamer and the on-surface cyclodehydrogenation of this precursor over a gold substrate. The resulting triangulene nanostar exhibits a collective spin state generated by the interaction of its 12 unpaired {\pi}-electrons along the conjugated lattice, corresponding to the antiferromagnetic ordering of six S = 1 sites (one per triangulene unit). Inelastic electron tunneling spectroscopy resolved three spin excitations connecting the singlet ground state with triplet states. The nanostar behaves close to predictions from the Heisenberg model of a S = 1 spin ring, representing a unique system to test collective spin modes in cyclic systems.Comment: 8 pages Ms with 3 figures; 12 pages Supplementary Informatio