Estudio teórico de la estructura y la dinámica de un nanofluido con partículas de CuO

Resumen del proyecto de líneas prioritarias titulado "Estudio teórico de la estructura y la dinámica de un nanofluido con partículas de CuO" del IMEYMAT

Interface chemistry effects in nanofluids: Experimental and computational study of oil-based nanofluids with gold nanoplates

The chemistry of interfaces and its relation with energy storage at and transport through solid-liquid interfaces in heat transfer nanofluids is a very unexplored terrain. Here we discuss how the magnitude of the changes in specific heat and thermal conductivity of the base fluid, upon dispersion of a nanoma-terial, depends on the surface chemistry of that nanomaterial. We focus on nanofluids with Au nanoplates from an integrated experimental and theoretical perspective, and compared our findings with those pre-viously reported for nanofluids with Pd nanoplates in the same base fluid. Pd and Au are known to have different surface chemistry, and so are the structures of the solid-liquid interfaces and the thermal prop-erties of these nanofluids. It was experimentally found that for mass fractions in the order of 0.01 wt%, Pd and Au nanoplates provide enhancements of 5.9% and 1.6% in specific heat, and enhancements of 12.5% and 17.9% in thermal conductivity, at 373 K. It was verified using density functional theory and classical molecular dynamics simulations that base fluid molecules can chemisorb on Pd surfaces, but not on Au surfaces. This work suggests that the stronger interactions between species at solid-liquid interfaces, the higher the specific heat enhancements and the lower the thermal conductivity enhancements at high temperature.(c) 2022 The Author(s). Published by Elsevier B.V

Problemas de mecánica cuántica molecular

El libro Problemas de Mecánica Cuántica Molecular se ha escrito con el objetivo de suministrar al lector una explicación detallada y "autosuficiente" de todos los problemas propuestos en el texto de teoría "Elementos de Mecánica Cuántica Molecular".747 págs

NiO nanowire-containing heat transfer nanofluids for CSP plants: Experiments and simulations to promote their application

Concentrating solar power (CSP) is considered a clean, renewable and sustainable energy with a significant potential to become an alternative to polluting fossil fuel-based technologies. Among CSP collectors, parabolic-trough collectors (PTC) are the most mature technology, representing nearly 90% of the currently installed collectors in CSP plants worldwide. In this technology, a heat transfer fluid (HTF) carries the thermal energy absorbed to a power block to produce electricity. Improving the thermal properties of the conventional HTF could lead to an improvement of the efficiency of CSP plants. In this sense, the use of nanofluids as the HTF in these plants can be a promising choice. Here, polycrystalline NiO nanowirecontaining nanofluids have been prepared using the conventional HTF used in CSP plants as the base fluid; that is, the eutectic and azeotropic mixture of biphenyl (26.5%) and diphenyl oxide (73.5%). The stability, rheological and thermal properties have been characterized, and an analysis of the performance of the nanofluids prepared in standard and volumetric absorbers have been carried out. The overall CSP system performance can be increased up to 34.8% using the nanofluid in a surface collector or up to 34.3% using the nanofluid in a volumetric collector, which are better than the predicted 28.5% using the conventional HTF in a standard surface collector, thanks to the improvements in thermal properties, both specific heat and thermal conductivity. Finally, from molecular dynamics simulations we determined that the mean free path of thermal vibrations is longer for monocrystalline NiO nanowires. Thus, the development of strategies for obtaining this kind of nanostructures is of great interest because they can further improve the efficiency of these nanofluids

Bond reactivity indices approach analysis of the [2+2] cycloaddition of jatrophane skeleton diterpenoids from Euphorbia gaditana Coss to tetracyclic gaditanone

The reaction mechanism of the intramolecular [2 + 2] cycloaddition from a jatrophane precursor to the gaditanane skeleton, an unprecedented 5/6/4/6-fused tetracyclic ring framework recently isolated from Euphorbia spp., was studied using the bond reactivity indices approach. Furthermore, six diterpenoids, including three undescribed jatrophanes isolated from E. gaditana Coss, were described. The structures of these compounds were deduced by a combination of 2D NMR spectroscopy and ECD data analysis

New Eremophilane-Type Sesquiterpenes from the Marine Sediment-Derived Fungus Emericellopsis maritima BC17 and Their Cytotoxic and Antimicrobial Activities

The fungal strain BC17 was isolated from sediments collected in the intertidal zone of the inner Bay of Cadiz and characterized as Emericellopsis maritima. On the basis of the one strain–many compounds (OSMAC) approach, four new eremophilane-type sesquiterpenes (1–4), together with thirteen known derivatives (5–17) and two reported diketopiperazines (18, 19), were isolated from this strain. The chemical structures and absolute configurations of the new compounds were determined through extensive NMR and HRESIMS spectroscopic studies and ECD calculation. Thirteen of the isolated eremophilanes were examined for cytotoxic and antimicrobial activities. PR toxin (16) exhibited cytotoxic activity against HepG2, MCF-7, A549, A2058, and Mia PaCa-2 human cancer cell lines with IC50 values ranging from 3.75 to 33.44 µM. (+)-Aristolochene (10) exhibited selective activity against the fungal strains Aspergillus fumigatus ATCC46645 and Candida albicans ATCC64124 at 471 µM

Delaying surgery for patients with a previous SARS-CoV-2 infection

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