Browsing by Author "Aguilar, C."
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- ItemAn updated look at drying shrinkage of Portland and blended Portland cement concretes(2006) Videla, C.; Aguilar, C.National and overseas reports clearly show that a significant proportion of concrete construction problems are associated with drying shrinkage. These results could be a result of few available long-term drying shrinkage data and changes of the behaviour of concrete mixes used nowadays. Therefore, poor estimates of drying shrinkage strains from prediction models could impair the performance and service life of concrete structures. The objective of the current research was to analyse the effect of mix design parameters on drying shrinkage of concretes made with Portland and blended Portland cements, considering 30 mixes that are commonly used in local construction, tested up to 1350 days of drying. It was concluded that, when using rapid-hardening cement of any type, a larger maximum aggregate size and lower water content reduces drying shrinkage. Cement and aggregate type are shown to have a significant effect on drying shrinkage time function and magnitude. Experimental results were compared with calculated drying shrinkage strains estimated by ACI 209, CEB MC90, B3, GL 2000, Sakata 1993 and Sakata 2001 models. It was concluded that none of the shrinkage prediction models adequately reproduced the observed shrinkage behaviour of concrete made with Chilean Portland and blended Portland cements, underestimating the actual long-term drying shrinkage strains.
- ItemCetoacidosis por estrés : caso clínico en paciente con atrofia muscular espinal(2020) Aguilar, C.; Sepúlveda Palamara, Rodrigo Andrés; Tagle, Rodrigo
- ItemEffect of added porosity on a novel porous Ti-Nb-Ta-Fe-Mn alloy exposed to simulated body fluid(2020) Guerra Figueroa, Carolina Andrea; Sancy, Mamié; Walczak, Magdalena; Martínez, Constanza; Ringuede, A.; Cassir, M.; Han, J.; Ogle, K.; Melo, H. G. de; Salinas, V.; Aguilar, C.
- ItemEffect of porosity on mechanical and electrochemical properties of Ti-6Al-4V alloy(2020) Martínez, Constanza; Guerra Figueroa, Carolina Andrea; Silva, D.; Cubillos, M.; Briones, F.; Muñoz, L.; Paez, M. A.; Aguilar, C.; Sancy, Mamié
- ItemEffect of Sn content on the passivity of Ti-Ta-Sn alloys(2023) Valverde, B.; Sancy, M.; Martinez, C.; Botello, E.; Pio, E.; Aguilar, C.In this work, Ti-13Ta-xSn samples were manufactured using the powder metallurgy technique with a porosity near 35 %. The microstructural analysis revealed that increased Sn content decreased the alpha-Ti and alpha'-Ti phases. Furthermore, scanning electron microscopy and X-ray photoelectron spectroscopy showed that the chemical composition of the passive oxide film was influenced by the Sn content. Moreover, the electrochemical analysis revealed that the protective properties of oxide film improved with the Sn addition.
- ItemEvolution of synthesis of FCC nanocrystalline solid solution and amorphous phase in the Ti-Ta based alloy by high milling energy(2021) Aguilar, C.; Pio, E.; Medina, A.; Martinez, C.; Sancy, M.; Guzman, D.Pure Ti and Ti-based alloys exhibit two equilibrium phases: at lower temperatures they have a hexagonal close packed (alpha-Ti) crystalline structure while at higher temperatures they possess a body-centered cubic (beta-Ti) structure. However, in special conditions, they could exhibit a metastable face-centered cubic (gamma-Ti) crystalline structure. This paper aims to investigate the influence of Sn amount and milling time on the formation of gamma-Ti phase on the Ti-Ta based alloy. Four alloys with compositions Ti-13Ta-xSn (x: 3, 6, 9 and 12 at. %) were obtained by high energy milling. The alloys were analyzed by X-ray diffaction patterns, transmission and scanning electron microscopy. For the Ti-13Ta-3Sn alloy, the beta-Ti phase is formed in greater quantity, similar to 70% at 100 h. For the Ti-13Ta-6Sn and Ti-13Ta-9Sn alloys, the phase that is in greater quantity is gamma-Ti, around 100% at 100h. The Ti-13Ta-6Sn alloy shows a greater tendency to form the gamma-Ti phase, since the quantity is close to 100% at 50 h milling time. Thermodynamic calculations are comparable with experimental data. The calculations were made using the MAAT software based on Miedema's model. The MAAT is a free software that can be download from www.rpm.usm.cl. (C) 2020 Elsevier B.V. All rights reserved.
- ItemImproving mechanical properties and antibacterial response of a/b ternary Ti-Ta alloy foams for biomedical uses(2023) Aguilar, C.; Martin, F. San; Martinez, C.; Camara, B.; Claverias, F.; Undabarrena, A.; Sancy, M.; Salinas, V.; Munoz, L.This study investigates the potential of Ti-Ta-Sn alloys for biomedical applications due to their excellent mechanical properties and biocompatibility, with a particular focus on their use in trabecular bone replacement. This work aims to analyze the influence that of Sn has on the mechanical properties and antibacterial response of a -b ternary Ti-13Ta-xSn (x:3, 6, 9, and 12 at.%) alloy foams. The Ti-based alloys were designed considering three aspects; (i) final microstructure, (ii) alloying element types, and (iii) thermodynamics while using MAAT and ThermoCalc software. The alloys were obtained by mechanical alloying, with used milling times being 30 h for Ti-13Ta-3Sn, 10 h for Ti-13Ta-6Sn, 10 h for Ti-13Ta-9Sn, and 15 h for Ti-13Ta-12Sn. The foams were obtained using NaCl as the space holder (50 v/v% porosity) and consolidated by a hot pressing method at 780 & DEG;C for 30 min, applying a load of 40 MPa. Both the Staphylococcus aureus ATCC 6538 strain and Escherichia coli ATCC 8739 strain were used to evaluate the antibacterial responses of Ti-based alloy foams. The Ti-based alloy foams were composed mostly by a mix of a and b-phases. The metallic foams exhibited relative homogeneous pore distribution with a size between 100 and 450 mm and having an average porosity slightly higher than 50%. The samples showed elastic modulus values be-tween 1 and 2 GPa, compressive yield strengths over 150 MPa, and microhardness over 450 HV. All Ti-based alloy foams showed no antibacterial activity nor bacterial adhesion, indicating that there is bacterial adhesion inhibition.& COPY; 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
- ItemInfluence of the synthesis technique on tribological behavior of a Ti-6Al-4V alloy(2020) Martinez, C.; Briones, F.; Araya, N.; Aguilar, C.; Machado, I.; Guerra Figueroa, Carolina Andrea; Medina, A.; Sancy, Mamié
- ItemLatin American Registry of Pediatric Renal Transplantation 2004-2008(2010) Goulart, P.; Koch, P.; Medina-Pestana, J.; Garcia, C.; Bittencourt, V.; Medeiros, M.; Munoz, R.; Delucchi, A.; Lillo, A. M.; Ariza, M.; Bosque, M.; Carvalho, D.; Matuck, T.; Meneses, R.; Fontes, J.; Monteiro, D. C.; Neto, E. Davi; Pinto, V.; Salas, P.; Prates, L.; Belanguero, V.; Pereira, L.; Lima, E.; Penido, J. M.; Benini, V.; Laranjo, S.; Silva, J. M.; Orta, N.; Coronel, V.; Cisneros, A.; Arriaga, J.; Sebastian, M. J.; Abbud-Filho, M.; Fernandez, I.; Gastelbondo, R.; Medjia, N.; Rosati, P.; Hevia, P.; Baptista, M. A.; Ramalho, H.; Diaz, M.; Monteverde, M.; Ferraris, J.; Repetto, H.; Exeni, R.; Florentin, L.; Florin, J.; Cazorla, N.; Casadei, D.; Melendez, K.; Calderon, R.; Silva, V.; Patino, J.; Palacio, D.; Madrigal, G.; Sandoval, M.; Urbina, C.; Loza, R.; Cavagnaro, F.; Vogel, A.; Jimenez, W.; Lou, R.; Rodriguez, C.; Aguilar, C.; Galvez, H.; Rodriguez, L.; Paladini, J.; Agusti, J.; Puelma, F.; Troche, A.; Martinez-Pico, M.; Higueras, W.; Liendo, C.; Restrepo, J.; Caicedo, L. A.; Socorro, F.; Semprum, P.The Latin American Pediatric Nephrology Association (ALANEPE) reports the first regional kidney transplant registry in Latin America. A mean range of 75%, 30% to 100% renal transplant recipients under 21 yr old were included. Out of 20 countries invited to participate, 14 performed renal transplant, 11 had universal financial support from their governments. The centers included: Brazil (9), Argentina (4), Chile (4), Venezuela (3), Mexico (2), and one in: Cuba, Colombia, Costa Rica, Nicaragua, Guatemala, Ecuador, Honduras, Paraguay and Peru. The registry included 1458 patients, average of 291 per year, 55% male. Mean follow-up 23.4 +/- 17 months; mean age was 11.7 +/- 4.3 yr (1-21), 11% under five yr of age. Etiology: uropathy/ reflux nephropathy 27%, glomerulopathies 24% (included 12% FSGS), hypo/dysplasia (11%), vascular (6%), congenital/hereditary (5%), unknown (19%). Induction therapy: 71% anti-IL2RAb, 13% ATG/TIMO, 14% non-induction. Maintenance therapy: Tacrolimus 64%, Cyclosporine 32%, MMF 54%, MPS 20%, noTORi 96%, steroids 90%, withdrawal or steroid avoidance 10%. Loss of graft 155/1458 (11%), death with functioning graft (3.4%), vascular thrombosis (2.8%), acute rejection (2.8%), recurrence of disease (1%). Forty-eight patients died (3.3%); infection was the main cause 23 (2.1%). Global patient survival rate at one, three, and five yr was 97%, 96%, and 96%. Graft survival rate at one, three, and five yr LRD was 96%, 93% and 89%; for DD 92%, 86% and 76% respectively. Both survival rates were higher in LRD (p < 0.008 and p < 0.001). A pediatric renal transplant study has started, making information available to be shared between the centers and the world.
- ItemPowder Metallurgy Production of Ti-2 Wt Pct Si Alloy : Structural, Mechanical, and Electrochemical Characterization of the Sintered Material(2020) Guzman, D.; Muranda, D.; Soliz, A.; Aguilar, C.; Guzman, A.; Sancy, Mamié; Pineda Parra, Fabiola Makarena; Rojas, P.
- ItemSupplementation, stocking rates, and economic performance of lamb production systems in the Mediterranean-type region of Chile(2006) Aguilar, C.; Vera, R.; Allende, R.; Toro, P.A simulation model was developed and validated to analyze the bioeconomic performance of alternative technologies applied to lamb production systems in the Mediterranean-type rangelands of Central Chile. The model includes consideration of climatic events that affect pasture growth, the nutritive value of the forage on offer, and animal performance as affected by energy and protein intake of directly grazed native pastures and supplements.
- ItemTechnical efficiency and viability of organic dairy sheep farming systems in a traditional area for sheep production in Spain(2011) Toro-Mujica, P.; Garcia, A.; Gomez-Castro, A. G.; Acero, R.; Perea, J.; Rodriguez-Estevez, V.; Aguilar, C.; Vera, R.The technical efficiency and viability of organic dairy sheep farming systems were investigated in Castilla-La Mancha, a Spanish region with a tradition of sheep rearing. The thirty one farms sampled, had an average of 359 ha, 508 sheep and 1.9 work units (WU); the reproductive rate was 1.5 lambs per ewe and year and the human productivity reached 303 sheep/Wu. There was however a high degree of variation among farms. Although the average level of technical efficiency was 66%, 74% of farms sampled operated at medium or low rates of technical efficiency. Differences in technical efficiency were largely due to the consumption of feeding supplements and productivity. A total of 45% of the farms was classified as non-viable. It was concluded that strategies for improving competitiveness and the use of resources are specific to each level of efficiency. The most efficient farms must increase their size; moderately efficient farms need to focus their efforts on improving the management of resources to enhance results. Improving competitiveness of the less efficient farms requires an increase of productivity; a better balance between the use of feeding supplements and the sheep productive capacity. (C) 2011 Elsevier B.V. All rights reserved.
- ItemThe effect of Staphylococcus aureus on the electrochemical behavior of porous Ti-6Al-4V alloy(2020) Silva Barbieri, Daniela Carolina; Guerra Figueroa, Carolina Andrea; Munoz, H.; Aguilar, C.; Walter, M.; Azocar, M.; Munoz, L.; Gurbuz, E.; Ringuede, A.; Sancy, Mamié; Cassir, M.
- ItemTribological Performance of Porous Ti-Nb-Ta-Fe-Mn Alloy in Dry Condition(2020) Guerra Figueroa, Carolina Andrea; Walczak, Magdalena; Sancy, Mamié; Martinez, C.; Aguilar, C.; Kalbarczyk, M.