Browsing by Author "Benitez, Diego"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    A mathematical model to simulate the cyclic behavior of exposed base plates with extended anchor bolts in steel moment frames subjected to earthquakes
    (2025) Torres Rodas, Pablo; Medalla, Miguel; López-García González, Diego; Herrera, Marco; Benitez, Diego; Camacho, Óscar
    This paper presents a mathematical model to predict the cyclic behavior of Exposed Base Plates with Extended Anchor Bolts (the EBP-EAB model) typically used in industrial and residential steel buildings in countries located in high seismic zones. The research is motivated by the potential integration of these connections as part of the energy dissipative mechanisms of steel moment frames due to their high deformation capacities and excellent hysteretic characteristics. The EBP-EAB model simulates the connection behavior as an arrangement of two parallel springs. The first spring consists of a trilinear backbone curve and a set of rules for describing unloading, reloading, pinching, and modes of cyclic deterioration for strength and stiffness. The second spring allows the simulation of the intermediate plateau observed in the connection response by means of a multi-linear elastic material, where the behavior is nonlinear but elastic. A total of 10 parameters are required to define the coordinates of the EBP-EAB model, where six parameters (core) are obtained using mechanical principles while the remaining four (ancillary) are obtained using a constrained optimization process. Four bio-inspired optimization algorithms were explored to find the best solutions to minimize the error defined in this paper for the empirical calibration of the ancillary parameters. Validation results show that the EBP-EAB model is capable of integrating the features of the nonlinear behavior observed in these connections with reasonable accuracy. Recommendations for estimating the core parameters are detailed, while limitations of the EBP-EAB model are outlined. Finally, as an example application, the model is implemented in a nonlinear dynamic analysis of a steel moment frame representative of an office building subjected to earthquake loading. Results indicate that the model is numerically robust and that the frame equipped with EBP-EABs achieves similar interstory drift demands to those with conventional base plate connections, while preventing plastic hinge formation in the columns.
  • No Thumbnail Available
    Item
    Mode of action of p-quinone derivatives with trypanocidal activity studied by experimental and in silico models
    (2023) Ballesteros-Casallas, Andres; Quiroga, Cristina; Ortiz, Cecilia; Benitez, Diego; Denis, Pablo A.; Figueroa, David; Salas, Cristian O.; Bertrand, Jeanluc; Tapia, Ricardo A.; Sanchez, Patricio; Miscione, Gian Pietro; Comini, Marcelo A.; Paulino, Margot
    Quinones are attractive pharmacological scaffolds for developing new agents for the treatment of different transmissible and non-transmissible human diseases due to their capacity to alter the cell redox homeostasis.The bioactivity and potential mode of action of 19 p-quinone derivatives fused to different aromatic rings (carbo or heterocycles) and harboring distinct substituents were investigated in infective Trypanosoma brucei brucei. All the compounds, except for a furanequinone (EC50=38 mu M), proved to be similarly or even more potent (EC50 = 0.5-5.5 mu M) than the clinical drug nifurtimox (EC50 = 5.3 mu M). Three furanequinones and one thia-zolequinone displayed a higher selectivity than nifurtimox. Two of these selective hits resulted potent inhibitors of T. cruzi proliferation (EC50=0.8-1.1 mu M) but proved inactive against Leishmania infantum amastigotes.Most of the p-quinones induced a rapid and marked intracellular oxidation in T. b. brucei. DFT calculations on the oxidized quinone (Q), semiquinone (Q center dot-) and hydroquinone (QH2) suggest that all quinones have negative Delta G for the formation of Q center dot-. Qualitative and quantitative structure-activity relationship analyses in two or three dimensions of different electronic and biophysical descriptors of quinones and their corresponding bioactivities (killing potency and oxidative capacity) were performed.Charge distribution over the quinone ring carbons of Q and Q.-and the frontier orbitals energies of SUMO (Q.-) and LUMO (Q) correlate with their oxidative and trypanocidal activity. QSAR analysis also highlighted that both bromine substitution in the p-quinone ring and a bulky phenyl group attached to the furane and thiazole rings (which generates a negative charge due to the 7C electron system polarized by the nearby heteroatoms) are favorable for activity.By combining experimental and in silico procedures, this study disclosed important information about p-qui-nones that may help to rationally tune their electronic properties and biological activities.