ZnO Materials as Effective Anodes for the Photoelectrochemical Regeneration of Enzymatically Active NAD+

This work reports the study of ZnO-based anodes for the photoelectrochemical regeneration of the oxidized form of nicotinamide adenine dinucleotide (NAD+). The latter is the most important coenzyme for dehydrogenases. However, the high costs of NAD+ limit the use of such enzymes at the industrial level. The influence of the ZnO morphologies (flower-like, porous film, and nanowires), showing different surface area and crystallinity, was studied. The detection of diluted solutions (0.1 mM) of the reduced form of the coenzyme (NADH) was accomplished by the flower-like and the porous films, whereas concentrations greater than 20 mM were needed for the detection of NADH with nanowire-shaped ZnO-based electrodes. The photocatalytic activity of ZnO was reduced at increasing concentrations of NAD+ because part of the ultraviolet irradiation was absorbed by the coenzyme, reducing the photons available for the ZnO material. The higher electrochemical surface area of the flower-like film makes it suitable for the regeneration reaction. The illumination of the electrodes led to a significant increase on the NAD+ regeneration with respect to both the electrochemical oxidation in dark and the only photochemical reaction. The tests with formate dehydrogenase demonstrated that 94% of the regenerated NAD+ was enzymatically active

One-Step Hydrothermal Synthesis of Cu2ZnSnS4 Nanoparticles as an Efficient Visible Light Photocatalyst for the Degradation of Congo Red Azo Dye

A hydrothermal method was successfully employed to synthesize kesterite Cu2ZnSnS4 (CZTS) nanoparticles. X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and optical ultraviolet-visible (UV-vis) spectroscopy were used for characterization of structural, chemical, morphological, and optical properties. XRD results confirmed that a nanocrystalline CZTS phase corresponding to the kesterite structure was formed. Raman analysis confirmed the existence of single pure phase CZTS. XPS results revealed the oxidation states as Cu+, Zn2+, Sn4+, and S2−. FESEM and TEM micrograph images revealed the presence of nanoparticles with average sizes between 7 nm to 60 nm. The synthesized CZTS nanoparticles bandgap was found to be 1.5 eV which is optimal for solar photocatalytic degradation applications. The properties as a semiconductor material were evaluated through the Mott–Schottky analysis. The photocatalytic activity of CZTS has been investigated through photodegradation of Congo red azo dye solution under solar simulation light irradiation, proving to be an excellent photo-catalyst for CR where 90.2% degradation could be achieved in just 60 min. Furthermore, the prepared CZTS was reusable and can be repeatedly used to remove Congo red dye from aqueous solutions.Partial funding for open access charge: Universidad de Málag

Rechargeable Lithium-Ion Battery Based on a Cathode of Copper Hexacyanoferrate

In this work, the performance of copper(II) hexacyanoferrate(III) (CuHCF) as a cathode material for lithium-ion batteries was studied. The compound was synthesized by a precipitation reaction in aqueous solution in a closed system. The morphology and structure show nanoparticles with sizes between 40 and 70 nm with a high agglomeration and a crystalline phase with a cubic structure, respectively. The material exhibited a stable performance with a working potential of around 3.6 V vs Li+/Li and a decrease in the charge transfer resistance due to increased ionic conductivity. The gravimetric capacity obtained is near 60 mAh g−1 during 300 cycles at a rate of C/20, close to the practical capacity. Considering its electrochemical performance, CuHCF could be a promising cathode material for lithium-ion batteries

Intracellular amyloid formation in muscle cells of Aβ-transgenic Caenorhabditis elegans: determinants and physiological role in copper detoxification

Background: The amyloid β-peptide is a ubiquitous peptide, which is prone to aggregate forming soluble toxic oligomers and insoluble less-toxic aggregates. The intrinsic and external/environmental factors that determine Aβ aggregation in vivo are poorly understood, as well as the cellular meaning of this process itself. Genetic data as well as cell biological and biochemical evidence strongly support the hypothesis that Aβ is a major player in the onset and development of Alzheimer's disease. In addition, it is also known that Aβ is involved in Inclusion Body Myositis, a common myopathy of the elderly in which the peptide accumulates intracellularly. Results: In the present work, we found that intracellular Aβ aggregation in muscle cells of Caenorhabditis elegans overexpressing Aβ peptide is affected by two single amino acid substitutions, E22G (Arctic) and V18A (NIC). Both variations show decrease intracellular amyloidogenesis compared to wild type Aβ. We show that intracellular amyloid aggregation of wild type Aβ is accelerated by Cu2+ and diminished by copper chelators. Moreover, we demonstrate through toxicity and behavioral assays that Aβ-transgenic worms display a higher tolerance to Cu2+ toxic effects and that this resistance may be linked to the formation of amyloid aggregates. Conclusion: Our data show that intracellular Aβ amyloid aggregates may trap excess of free Cu2+ buffering its cytotoxic effects and that accelerated intracellular Aβ aggregation may be part of a cell protective mechanism

Ciudadanías para la Democracia

Este libro se centra en la problemática constitucional y constituyente chilena del siglo XXI, en el marco del proceso constituyente impulsado por el segundo gobierno de Michelle Bachelet. Desde distintas perspectivas y grados de esperanza en dicho proceso, los ensayos reunidos abordan tanto ámbitos teóricos como aspectos específicos del mismo, con los debates de los años 2015-2017 como telón de fondo. El desfase de estas contribuciones respecto de los debates actuales se asume desde la necesidad de revisar con distancia crítica una serie de tópicos, que abren preguntas sobre los alcances de los problemas sin resolver que supone el orden constitucional y constituyente actual

Ciudadanías para la Democracia. Reflexiones desde la problemática constitucional y constituyente chilena del siglo XXI

Este libro está centrado, como lo indica su título, en la problemática constitucional y constituyente chilena del siglo XXI. Fue concebido en el marco del Proyecto U-redes “Ciudadanías para la democracia” de la Vicerrectoría de Extensión y Desarrollo de la Universidad de Chile, ejecutado por sus editores durante el bienio 2016-2017. Los textos reunidos fueron redactados el año 2017 cuando el proceso constituyente impulsado por el segundo gobierno de Michelle Bachelet parecía entrar -de acuerdo con los anuncios oficiales- en la recta final luego de desarrolladas distintas etapas, incluyendo algunos módulos de participación ciudadana (cabildos) de restringida convocatoria, a pesar de haber sido convocados mediante profusa propaganda oficial. Aunque solo algunas de las contribuciones recogidas en este volumen se refieren explícitamente a dicho proceso constituyente, todas se han planteado con temáticas que le dan sentido –sea vinculadas a ámbitos teóricos y más generales o, también, específicos que tuvieron como marco o telón de fondo los debates de los años 2015-2017. Desde distintas disciplinas de las Ciencias Sociales y las Humanidades y con mayores o menores grados de esperanza en dicho proceso (fluctuantes entre un optimista cambio inminente de régimen político y el escepticismo total debido a las trampas sistémicas y los contenidos del diseño del itinerario oficial), sus autores hicieron un aporte para la comprensión de tópicos que abren preguntas sobre los alcances de los problemas que implica el orden constitucional y constituyente que, desde hace décadas, están planteados como tareas a resolver por una sociedad atrapada en los mecanismos impuestos y remachados por los fundadores y defensores del orden neoliberal. La publicación de estas contribuciones, desfasada respecto de las prioridades y debates actuales (ya casi nadie evoca el tema constituyente en Chile), se justifica a nuestro entender porque los problemas aludidos no se han resuelto y, por ende, más temprano que tarde la imperiosa necesidad de solucionarlo volverá a aflorar en la conciencia ciudadana. A ello podríamos agregar que el tiempo transcurrido desde que estos textos fueron redactados dará a los lectores mayor distancia crítica para apreciar los aciertos y 8 debilidades de los análisis y esperanzas de unos y otros. De esta manera, tanto los supuestos y problematización teórica en algunos casos, como los análisis políticos y proyecciones que expresaron las apuestas políticas de los autores de este libro en el contexto del abortado proceso constituyente de los años 2015-2017, podrán servir de insumos para los debates y nuevas propuestas de acción que, estamos seguros, surgirán respecto de estos temas en los próximos años