Browsing by Author "Alzate-Morales, Jans"

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    Can graphene improve the thermal conductivity of copper nanofluids?
    (2023) Olguin-Orellana, Gabriel J. J.; Soldano, German J.; Alzate-Morales, Jans; Camarada, Maria B.; Mariscal, Marcelo M. M.
    Copper (Cu) nanofluids (NFs) have attracted attention due to their high thermal conductivity, which has conferred a wide variety of applications. However, their high reactivity favors oxidation, corrosion and aggregation, leading them to lose their properties of interest. Copper capped by graphene (Cu@G) core@shell nanoparticles (NPs) have also attracted interest from the medical and industrial sectors because graphene can shield the Cu NPs from undesired phenomena. Additionally, they share some properties that expand the range of applications of Cu NFs. In this work, new Morse potentials are reported to reproduce the behavior of Cu@G NPs through molecular dynamics. Coordination-dependent Morse parameters were fitted for C, H, and Cu based on density functional theory calculations. Then, these parameters were implemented to evaluate the thermal conductivity of Cu@G NFs employing the Green-Kubo formalism, with NPs from 1.5 to 6.1 nm at 100 to 800 K, varying the size, the number of layers and the orientation of the graphene flakes. It was found that Cu@G NFs are stable and have an improved thermal conductivity compared to the Cu NFs, being 3.7 to 18.2 times higher at 300 K with only one graphene layer and above 26.2 times higher for the graphene-trilayered NPs. These values can be higher for temperatures below 300 K. Oppositely, the size, homogeneity and orientations of the graphene flakes did not affect the thermal conductivity of the Cu@G NFs.
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    Neonicotinic analogues: Selective antagonists for α4β2 nicotinic acetylcholine receptors
    (2013) Faundez-Parraguez, Manuel; Farias-Rabelo, Nicolas; Pablo Gonzalez-Gutierrez, Juan; Etcheverry-Berrios, Alvaro; Alzate-Morales, Jans; Adasme-Carreno, Francisco; Varas, Rodrigo; Bermudez, Isabel; Iturriaga-Vasquez, Patricio
    Nicotine is an agonist of nicotinic acetylcholine receptors (nAChRs) that has been extensively used as a template for the synthesis of alpha 4 beta 2-preferring nAChRs. Here, we used the N-methyl-pyrrolidine moiety of nicotine to design and synthesise novel alpha 4 beta 2-preferring neonicotinic ligands. We increased the distance between the basic nitrogen and aromatic group of nicotine by introducing an ester functionality that also mimics acetylcholine (Fig. 2). Additionally, we introduced a benzyloxy group linked to the benzoyl moiety. Although the neonicotinic compounds fully inhibited binding of both [alpha-I-125]bungarotoxin to human alpha 7 nAChRs and [H-3]cytisine to human alpha 4 beta 2 nAChRs, they were markedly more potent at displacing radioligand binding to human alpha 4 beta 2 nAChRs than to alpha 7 nAChRs. Functional assays showed that the neonicotinic compounds behave as antagonists at alpha 4 beta 2 and alpha 4 beta 2 alpha 5 nAChRs. Substitutions on the aromatic ring of the compounds produced compounds that displayed marked selectivity for alpha 4 beta 2 or alpha 4 beta 2 alpha 5 nAChRs. Docking of the compounds on homology models of the agonist binding site at the alpha 4/beta 2 subunit interfaces of alpha 4 beta 2 nAChRs suggested the compounds inhibit function of this nAChR type by binding the agonist binding site. (C) 2013 Elsevier Ltd. All rights reserved.