Relación de la estructura con las propiedades eléctricas en solución sólida La2/3-xLi3xTiO3 (0.03 x 0.167)

En este trabajo se investigó la solución sólida La2/3-xLi3xTiO3 (0.03<x<0.167) por las técnicas de difracción de rayos-X en polvos (DRX), espectroscopía de impedancias (EI) y resonancia magnética nuclear (RMN) de 7Li. En estas muestras se observó un cambio en la simetría de tetragonal a ortorrómbica cuando disminuye el contenido de litio por debajo de x=0.06. Hallamos que las modificaciones estructurales producidas se deben principalmente al ordenamiento de las vacancias a lo largo del eje c. Estas modificaciones disminuyen gradualmente al incrementarse el contenido de litio en la solución sólida. Se detectaron dos señales de litio con diferente constante cuadrupolar para el espectro de RMN del 7Li en las perovskitas ortorrómbicas/tetragonales, las cuales asociamos con dos sitios cristalográficos para el litio dentro de la estructura. Para la perovskita de composición La0.5Li0.5TiO3, se realizó un experimento enfriándola rápidamente desde 1300° C en nitrógeno líquido. En ésta se detectó una elevada movili- dad del litio en el espectro de RMN del 7Li. Para las perovskitas analizadas, la dependencia de la conductividad eléctrica con el contenido de litio no sigue el comportamiento esperado, basado en la teoría de una distribución aleatoria de los átomos de La y Li sobre los sitios A. La conductividad DC aumenta rápidamente con el contenido de litio en las muestras ortorrómbicas, aunque el cambio es mucho más gradual en las tetragonales, donde la distribución de las vacancias se desordena progresivamente. En todas las perovskitas analizadas, la dependencia de la conductividad dc con la temperatura muestra un comportamiento no-Arrhenius con energías de activación de 0.39±0.02 eV y 0.29±0.02 eV en los rangos de temperatura de 160 – 250 y 250 – 360 K, respectivamente

Phenomenological Approach to the Meaning and Impact of Organ Donation in the Family

La donación de órganos es un acontecimiento crítico tras la pérdida de un ser querido. España, a pesar de ser el país del mundo con mayor tasa de donantes, todavía mantiene una negativa familiar del 15,56%. Objetivos: conocer y analizar el impacto de la donación de órganos a través de los significados que tiene para la familia en el contexto español. Materiales y método: estudio cualitativo fenomenológico según el marco conceptual y método de Giorgi. Luego de respetar, al menos, tres años de duelo desde la pérdida de un ser querido, se entrevistaron en profundidad a once familias que donaron órganos en el Hospital La Fe en Valencia. Resultados: tras el análisis de los resultados, se describieron veintisiete unidades de significado que fueron clasificadas en relativos a la pérdida y relativos a la donación de órganos y, posteriormente, correlacionadas. Conclusiones: la donación aparece como mecanismo de alivio o compensación del fallecimiento del familiar.Organ donation is a critical event after the loss of a loved one. Spain, despite being the country with the highest donor rate in the world, still maintains a family negative rate of 15.56%. Objective: Know and analyze the impact of organ donation based on its meaning for the family in the Spanish context. Materials and method: This is a phenomenological qualitative study based on Giorgi's conceptual framework and method. Eleven families who had donated organs at the Hospital La Fe in Valencia were interviewed in depth, following at least three years of mourning since the loss of a loved one. Results: After the results were analyzed, twenty-seven units of meaning were described and classified as relative to the loss and relative to the organ donation. They were then correlated. Conclusion: Organ donation appears to be a relief mechanism or a kind of compensation for the death of a family member

Influencia del enfriamiento en las propiedades de titanatos de lantano y litio

Se ha estudiado el efecto de los tratamientos a alta temperatura sobre la estructura y la movilidad del litio para la solución sÛlida Li3xLa2/3-xTiO3 (0.03<x<0.167) con difracciÛn de rayos X a alta temperatura (DRXAT), espectroscopia Raman, RMN y de impedancias. Los patrones de difracción de rayos X (DRX) a temperatura ambiente de muestras enfriadas lentamente muestran una estructura tipo perovskita doblada en el eje c con simetrÌas tetragonales u ortorrómbicas, mientras que las muestras con un enfriamiento r·pido muestran una estructura tipo perovskita c ̇bica simple. Sin embargo, el espectro Raman de las muestras analizadas se interpreta, en todos los casos, con una simetrÌa tetragonal en la que el desorden catiónico se incrementa con el contenido de litio y el tratamiento de enfriamiento. La existencia de microdominios de maclado, orientados a lo largo de las tres direcciones de la perovski- ta, favorece la detecciÛn de la fase c ̇bica en los patrones de DRX. A partir de la espectroscopia de RMN del 7Li, se ha detectado un movimiento bidi- mensional del litio en las muestras ordenadas, el cual se convierte progresivamente en un movimiento tridimensional conforme se incrementa el desorden catiÛnico. Asimismo, la presencia de microdominios hace disminuir la conductividad dc de muestras con contenidos bajos de litio

A Bridging bis-Allyl Titanium Complex: Mechanistic Insights into the Electronic Structure and Reactivity

Treatment of the dinuclear compound [{Ti(η5-C5Me5)Cl2}2(μ-O)] with allylmagnesium chloride provides the formation of the allyltitanium(III) derivative [{Ti(η5-C5Me5)(μ-C3H5)}2(μ-O)] (1), structurally identified by single-crystal X-ray analysis. Density functional theory (DFT) calculations confirm that the electronic structure of 1 is a singlet state, and the molecular orbital analysis, along with the short Ti −Ti distance, reveal the presence of a metal −metal single bond between the two Ti(III) centers. Complex 1 reacts rapidly with organic azides, RN3 (R = Ph, SiMe3), to yield the allyl μ-imido derivatives [{Ti(η5-C5Me5)(CH2CH=CH2)}2(μ-NR)(μ-O)] [R = Ph(2), SiMe3(3)] along with molecular nitrogen release. Reaction of 2 and 3 with H2 leads to the μ-imido propyl species [{Ti(η5-C5Me5)(CH2CH2CH3)}2(μ-NR)(μ-O)] [R = Ph(4), SiMe3(5)]. Theoretical calculations were used to gain insight into the hydrogenation mechanism of complex 3 and rationalize the lower reactivity of 2. Initially, the μ-imido bridging group in these complexes activates the H2 molecule via addition to the Ti −N bonds. Subsequently, the titanium hydride intermediates induce a change in hapticity of the allyl ligands, and the nucleophilic attack of the hydride to the allyl groups leads to metallacyclopropane intermediates. Finally, the proton transfer from the amido group to the metallacyclopropane moieties affords the propyl complexes 4 and 5.Ministerio de Ciencia, Innovación y Universidades Universidad de Alcalá Generalitat de Cataluny

Genetic characterization by amplified fragment length polymorphism (AFLP) markers and morphochemical traits of Carica papaya L. genotypes

Carica papaya L. is a native fruit from Central America and Mexico and it is an economically important fruit. As a pre-breeding genetic study, the variability of both parents (L7 and M22) and the F1 individuals derived from their crosses (L7 × M22), was evaluated in terms of 32 morphochemical traits, and contrasted with their genetic diversity indicated by amplified fragment length polymorphism (AFLP) markers. According to morphochemical traits, L7 and M22 were grouped in two different clades. The first group included L7 and 13 genotypes from the F1, while a second group included the parent M22 and 15 other genotypes from the F1 progeny. The analysis based on morphochemical traits showed an average correlation of 0.652 among genotypes. For AFLP analysis the combination of the primers E-ACA/M-CTA had the best polymorphic index (72.73%). When they were grouped based on AFLPs markers, it was confirmed that both parents are genetically distant, and they were again grouped in two different clades. Five genotypes from the F1 population were grouped in the same clade as L7 and shared 55% similarity. Twenty six genotypes were grouped in the same clade as M22, showing 63.3% similarity. Another 12 genotypes (mainly female genotypes) were grouped in a third independent clade. This relative general agreement between the grouping based on a large number of morphochemical traits (including both plant and fruit traits) and that based on its genetic diversity using AFLPs, suggests that morphochemical characterization, together with genetic analysis by AFLPs, can be complementary and useful techniques for the identification and assessment of genetic diversity within C. papaya L. genotypes, that should be useful for genetic breeding programs of this important species.Key words: Morphological markers, AFLP markers, genetic similarity, Carica papaya L

N=N Bond Cleavage by Tantalum Hydride Complexes: Mechanistic Insights and Reactivity.

A series of dinuclear tantalum(IV) hydrides [{TaCpRX2}2(mu-H)2] (CpR = eta5-C5Me5, eta5-C5H4SiMe3, eta5-C5HMe4; X = Cl, Br) show the ability to promote the N=N bond cleavage in their reactions with azobenzene and benzo[c]cinnoline in absence of reducing reagents. Both, characterization of intermediate species and DFT studies point to a mechanism in two stages, in which the Ta-Ta bond splitting is key for the reduction of the N=N bond and its complete scission.Consorcio Madroño - Universidad de Alcal

The Effectiveness of Glutathione Redox Status as a Possible Tumor Marker in Colorectal Cancer

[EN] The role of oxidative stress (OS) in cancer is a matter of great interest due to the implication of reactive oxygen species (ROS) and their oxidation products in the initiation of tumorigenesis, its progression, and metastatic dissemination. Great efforts have been made to identify the mechanisms of ROS-induced carcinogenesis; however, the validation of OS byproducts as potential tumor markers (TMs) remains to be established. This interventional study included a total of 80 colorectal cancer (CRC) patients and 60 controls. By measuring reduced glutathione (GSH), its oxidized form (GSSG), and the glutathione redox state in terms of the GSSG/GSH ratio in the serum of CRC patients, we identified significant changes as compared to healthy subjects. These findings are compatible with the effectiveness of glutathione as a TM. The thiol redox state showed a significant increase towards oxidation in the CRC group and correlated significantly with both the tumor state and the clinical evolution. The sensitivity and specificity of serum glutathione levels are far above those of the classical TMs CEA and CA19.9. We conclude that the GSSG/GSH ratio is a simple assay which could be validated as a novel clinical TM for the diagnosis and monitoring of CRC.This work was partially supported by grants GST, UGP-19-037 FISABIO, Universitat Politecnica de Valencia-the Hospital Universitario Doctor Peset POLISABIO collaboration program (UPV-FISABIO) NanOdGSens-2, the Spanish Government project RTI2018-100910-B-C41 (MCUI/AEI/FEDER, UE), the Generalitat Valenciana project PROMETEO/2018/024 and PI18/00932 by Instituto de Salud Carlos III and co-funded by the European Regional Development Fund (ERDF "A way to build Europe"). C.B. is a recipient of a Miguel Servet contract (CP19/00077) from the Instituto de Salud Carlos III.Acevedo-León, D.; Monzó-Beltrán, L.; Gómez-Abril, SÁ.; Estañ-Capel, N.; Camarasa-Lillo, N.; Pérez-Ebri, ML.; Escandón-Álvarez, J.... (2021). The Effectiveness of Glutathione Redox Status as a Possible Tumor Marker in Colorectal Cancer. International Journal of Molecular Sciences. 22(12):1-15. https://doi.org/10.3390/ijms22126183115221