Evaluación de las propiedades biológicas de antioxidantes fenólicos en subproducto de uva, café verde y yerba mate como ingredientes funcionales o nutracéuticos

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Agrícola y Bromatología. Fecha de lectura: 22-11-201

Histidine‐mediated synthesis of chiral cobalt oxide nanoparticles for enantiomeric discrimination and quantification

Chiral transition metal oxide nanoparticles (CTMOs) are attracting a lot of attention due to their fascinating properties. Nevertheless, elucidating the chirality induction mechanism often remains a major challenge. Herein, the synthesis of chiral cobalt oxide nanoparticles mediated by histidine (Co3O4@L-His and Co3O4@D-His for nanoparticles synthesized in the presence of L- and D-histidine, respectively) is investigated. Interestingly, these CTMOs exhibit remarkable and tunable chiroptical properties. Their analysis by x-ray photoelectron, Fourier transform infrared, and ultraviolet-visible absorption spectroscopy indicates that the ratio of Co2+/Co3+ and their interactions with the imidazole groups of histidine are behind their chiral properties. In addition, the use of chiral Co3O4 nanoparticles for the development of sensitive, rapid, and enantioselective circular dichroism-based sensors is demonstrated, allowing direct molecular detection and discrimination between cysteine or penicillamine enantiomers. The circular dichroism response of the chiral Co3O4 exhibits a limit of detection and discrimination of cysteine and penicillamine enantiomers as low as 10 µm. Theoretical calculations suggest that the ligand exchange and the coexistence of both species adsorbed on the oxide surface are responsible for the enantiomeric discrimination. This research will enrich the synthetic approaches to obtain CTMOs and enable the extension of the applications and the discovery of new chiroptical properties.National Natural Science Foundation of China | Ref. 22271257Agencia Estatal de Investigación | Ref. PID2019-108954RB-I00Xunta de Galicia | Ref. ED431C 2020/09Universidade de Vigo/CISU

Gas adsorption properties of ZSM-5 zeolites heated to extreme temperatures

Zeolites are broadly useful catalysts and molecular sieve adsorbents for purification. In this work the thermal degradations of bare and platinum-loaded ZSM-5 was studied with the goal of understanding the behavior of nanoporous solids at extreme temperatures comparable to those present in nuclear fuels. Zeolites were heated in air and nitrogen at temperatures up to 1500 °C, and then characterized for thermal stability via X-ray diffraction (XRD) and for gas adsorption by the Brunauer-Emmett-Teller (BET) method. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were also employed. These results indicate zeolites are stable when heat-treated up to 800 °C and degrade slowly at higher temperatures. However, significant surface area degradation begins at 1025–1150 °C with an activation energy of 400 kJ/mole. At 1500 °C, gas adsorption measurements and SEM images show complete collapse of the porous structure. Critically for nuclear fuel applications, however, the zeolites still adsorb helium in significant quantities

Evaluation of biological properties of phenolic antioxidants in grape pomace,green coffee and yerba mate as functional ingredients or nutraceuticals

Memoria que presenta Shenli Wang para optar al grado de Doctor por la Universidad Autónoma de Madrid.Estudios epidemiológicos han mostrado repetidamente un asociación inversa entre el riesgo de enfermedades crónicas y el consumo de una dieta rica en compuestos fenólicos. La uva es uno de los cultivos de mayor producción hortofrutícola en el mundo, siendo un alimento muy rico en polifenoles. Su empleo en la elaboración de vino produce una gran cantidad de subproductos de uva, con un alto contenido en polifenoles, principalmente antocianos (en uva tinta), catequinas, glicósidos de flavonoles, ácidos y alcoholes fenólicos y estilbenos. Por tanto, los subproductos de uva son una importante fuente de antioxidantes fenólicos, siendo importante evaluar sus propiedades biológicas para profundizar en el conocimiento del potencial de este producto como ingrediente funcional o nutracéutico. La yerba mate y el café destacan entre las bebidas más populares mundialmente. El café verde y el mate tienen una composición fenólica similar. El café verde contiene ácidos clorogénicos, cinamoil amidas y glicósidos y ácidos fenólicos libres, mientras que la yerba mate además de estos ácidos hidroxicinámicos contiene flavonoles como la rutina y otros glicósidos de flavonoles. Además de su creciente consumo como ingredientes en nutracéuticos, el mate es ampliamente consumido como infusión, mientras que la ingesta de café verde como infusión o en mezcla con café tostado está incrementando en los últimos años como una alternativa más saludable al café tostado. Las propiedades biológicas de los flavonoides han sido extensivamente estudiadas; asimismo, en los últimos años ha ganado interés y presencia en la literatura científica los estudios sobre ácidos clorogénicos. Sin embargo, otros ácidos fenólicos han sido menos estudiados in vitro e in vivo, e igualmente, los estudios sobre la actividad biológica de metabolitos circulantes son todavía muy escasos. Por otro lado, el empleo de líneas celulares inmortalizadas como modelo para el estudio de los efectos quimioprotectores de fitoquímicos, entre otras actividades biológicas, es ampliamente aceptado. La hipótesis de esta tesis fue que los subproductos de uva, el café verde y la yerba mate, como productos ricos en compuestos fenólicos, pueden presentar propiedades biológicas que podrían resultar en efectos beneficiosos para la salud, particularmente en enfermedades asociadas con el estrés oxidativo y, por tanto, pueden presentar relevancia como ingredientes funcionales o nutracéuticos.This Doctoral Thesis has been supported by the following funding: -PhD Scholarship Chinese Scholarship Council (Chinese Government, CSC No. 201206350027) from September 2012 to August 2016. Beca predoctoral del Consejo de Educación del Gobierno Chino (sept 2012-agosto 2016). -The Spanish Ministry of Economy and Competitiveness, R+D+R Spanish National plan projects AGL2010-18269 and AGL2015-69986-R. Los proyectos AGL2010-18269 and AGL2015-69986-R del Plan Estatal de I+D+I, Ministerio de Economía y Competitividad. -The Ministry of Economy and Competitiveness, R+D+R Consolider-Ingenio CSD2007-00063 and INCOMES. Proyecto Consolider-Ingenio CSD2007-00063 e INCOMES del Plan Estatal de I+D+I, Ministerio de Economía y Competitividad. -Joint Collaborative Project among R+D Technology research groups in the Community of Madrid S2013/ABI-3028, Community of Madrid (Spain). Proyecto S2013/ABI-3028 del Programa de Actividades de I+D entre grupos de investigación de la Comunidad de Madrid en Tecnologías. -Spanish National Research Council (CSIC) Project PIE201670E061. Proyecto PIE201670E061 del Consejo Superior de Investigaciones Científicas (CSIC, España).Peer Reviewe

Measurement and simulation analysis of internal pressure in arc chamber of low-voltage molded case circuit breaker

During the arc interruption process, the internal pressure in the arc chamber of a molded-case circuit breaker (MCCB) rises rapidly. In this study, the arc behavior and internal pressure in an MCCB are measured and calculated. First, using computational fluid dynamics, the internal pressure in the arc chamber is computed both with and without a baffle. In the presence of the baffle, it is found that the pressure is similar at various measurement points, whereas without the baffle, obvious differences in pressure are observed. Second, a moving model considering the contact opening process is proposed based on the relationships between the arc positions, arc area, and source terms at a typical point in time. Compared with a fixed arc model, the moving arc model provides a more precise arc distribution and pressure in the arc chamber of an MCCB

Modeling of mixing and interaction of multi-cathode spot vacuum arc jets

Vacuum arc consists of cathode spot and mixing zone, arc column and anode zone. The separate jets and the mixing zone should be considered in the model of diffuse arc. Moreover, the interaction between the plasma jets in multi-cathode spot vacuum arc also is very important. In this paper, mixing and interaction of multi-cathode spot vacuum arc jets were studied through simulation. To completely investigate the mixing and interaction of vacuum arc jets, a steady 3D Magneto-Hydro-Dynamic (MHD) modeling was established. In order to find out the influence of different parameters on mixing and interaction of vacuum arc jets, simulations with different parameters such as currents, angel of vacuum arc jets, with or without electromagnetic equations, tilted jets and different height of mixing zone were conducted. The simulation results show that the densities of ion number and plasma pressure as well as ion temperature increase with the increase of arc current, while the plasma velocity decreases. The jet center is more deviated from the cathode center with the increase of angle of tilted jets

La protección endotelial producida por yerba mate y café verde está asociada al ácido clorogénico y su principal metabolito colónico, el ácido dihidrocaféico

Resumen del póster presentado al IX Congreso CyTA-CESIA, celebrado en Madrid del 16 al 19 de mayo de 2017.Yerba mate and green coffee bean extracts protect EA.hy926 endothelial cells against tumour necrosis factor alpha induced endothelial dysfunction, playing 5-caffeoylquinic acid, their major phenolic compound, and dihydrocaffeic acid, their major microbial metabolite, even at low physiologically relevant concentrations an important role in the protective effect.Shenli Wang thanks the Chinese Government for her PhD Scholarship. This work was supported by projects AGL2010-18269 and AGL2015-69986-R and project PIE-201670E061 funded by CSIC.Peer Reviewe

Modeling of CuCr contact vacuum arc with consideration of its components

This paper involves the simulation of vacuum arc under composite (CuCr) contact. A three dimensional model is developed and we have considered the ionization process as well as recombination in the vacuum arc. The species transport equations, in which the fraction of each component is calculated, provides the distribution of various atoms and ions in vacuum arc. The model describes ions and atoms as two different processes considering that ions are influenced by self-generated magnetic field. Atoms play an inferior role in the process of vacuum arc. They gather in an ‘atom layer’ whose thickness is no more than 1mm and outside the atom layer the density of atoms declines by at most 5 orders of magnitude. The ionization process is dominated by electron temperature. The distribution of ion species is closely related to the degree of ionization. At cathode, singly charged ions are dominant. From cathode to anode, ions are ionized so that doubly charged ions become the major component at anode where singly charged ions reach their minimum density. Finally, the ionization rate is also influenced by the ionization potential of each component, so the fraction of Cr1+ is smaller than Cu1+ while Cr2+ is larger than Cu2+ in the anode center