Browsing by Author "Leiva, A."
Now showing 1 - 12 of 12
Results Per Page
Sort Options
- ItemA facile approach for tuning optical and surface properties of novel biobased Alginate/POTE handleable films via solvent vapor exposure(ELSEVIER, 2021) Mendez Lopez, M.; Ramos Hernandez, A.; Moreno Serna, V.; Bonardd, S.; Ramirez, O.; Silva, Hernan; Inostroza Rivera, Ricardo; Diaz, D. Diaz; Leiva, A.; Saldias, C.Novel biobased films consisting of alginate blends with poly (octanoic acid 2-thiophen-3-yl-ethyl ester) (POTE), a conducting polymer, were prepared by solution casting, and their optical, morphological, thermal, and surface properties were studied. Using UV-visible spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), the effects of tetrahydrofuran solvent vapors on the optical properties and surface morphology of biobased films with different POTE contents were studied. Results indicate that morphological rearrangements of POTE take place during the process of solvent exposure. Specifically, the solvent vapor induced the formation of POTE small crystalline domains, which allows envisioning the potential of tuning UV-visible absorbance and wettability behavior of biobased films. Finally, theoretical electronic calculations (specifically frontier molecular orbitals analysis) provided consistent evidence on POTE's preferential orientation and selectivity toward the THF-vapor medium.
- ItemAromatic rigid poly(urethanes) containing silicon and/or germanium in the main chain(2005) Terraza Inostroza, Claudio; Tagle Domínguez, Luis Hernán; Leiva, A.
- ItemEfectos clínicos del entrenamiento muscular inspiratorio en pacientes con limitación crónica del flujo aéreo(1995) Lisboa Basualto, Carmen; Villafranca, Carlos; Pertuzé, Julio; Leiva, A.; Repetto Lisboa, Paula BeatrizThe clinical role of inspiratory muscle training (IMT) in chronic obstructive pulmonary disease (COPD) has not been established, because data on its clinical effect is scarce and controversial. To further investigate these aspects we studied 20 COPD patients (FEV1 37 +/- 3% P) who were randomly and double blindly trained for 30 minutes a day during 10 weeks using a threshold inspiratory trainer with either 30% (group 1) or 10% (group 2) of PIMax as a training load. The training load was crossed after each patient completed 10 weeks of training. Effects were assessed through changes in PIMax, dyspnea through the transition dyspnea index (ITD) and the respiratory effort with Borg's score. Walking capacity was measured with the six minutes walking distance test (6WD) and depression symptoms with Beck's score. Daily life activities were also assessed. Results showed that after 10 weeks of IMT, PIMax increased in both groups (p < 0.05), dyspnea improved in group 1 as compared to group 2 (p < 0.04), 6WD increased significantly in patients of group 1, who also complained of less dyspnea (p < 0.05). Depression scores fell significantly in group 2. Daily activities improved more in group 1. After the crossover patients in group 1 disclosed a significant deterioration in PIMax whereas group 2 disclosed significant improvements in PIMax, dyspnea and 6WD. We conclude that IMT using a threshold device with 30% PIMax is a useful procedure for the treatment of severe COPD patients.
- ItemENDOPLASMIC RETICULUM STRESS IN HUMAN UMBILICAL VEIN ENDOTHELIAL CELLS FROM PRE-GESTATIONAL MATERNAL OBESITY(W B SAUNDERS CO LTD, 2017) Villalobos Labra, R.; Salsoso, R.; Subiabre, M.; Silva, L.; Farias Jofre, M.; Leiva, A.; Sobrevia, L.
- ItemInsulin Is a Key Modulator of Fetoplacental Endothelium Metabolic Disturbances in Gestational Diabetes Mellitus(2016) Sobrevía Luarte, Luis Alberto; Salsoso Rodríguez, M. Rocío; Fuenzalida Saavedra, Bárbara; Barros Lamus, Eric Raúl; Toledo Valenzuela, Lilian Alejandra; Silva Lagos, Luis Alfredo; Pizarro, C.; Subiabre Morales, Mario Enrique; Villalobos, R.; Araos, J.; Toledo, F.; Gonzalez, M.; Gutierrez, J.; Farías Jofré, Marcelo Enrique; Chiarello, D.; Pardo, F.; Leiva, A.
- ItemInterfacial behavior of PAMAM-PCL dendrimers and in situ spontaneous formation of gold nanoparticles at the toluene-water and air-water interfaces: Experimental and theoretical studies(2016) Saldías, César; Méndez Lesser, Manuel; Saavedra, M.; Pereira, A.; Rojas, M.; Avila, F.; Bonardd Salvador, Sebastián Ignacio; Pino, M.; Saldías, S.; Quezada, C.; Leiva, A.; Radić Foschino, Deodato D.
- ItemModulation of Intracellular pH in Human Ovarian Cancer(2016) Sanhueza, C.; Araos, J.; Naranjo, L.; Villalobos Labra, Roberto Esteban; Westermeier, F.; Salomon, C.; Beltran, A.; Ramirez, M.; Gutierrez, J.; Pardo, F.; Leiva, A.; Sobrevía Luarte, Luis Alberto
- ItemNew Polymers Based on 2,6-di(thiophen-2-yl) aniline and 2,2 '-(thiophen-2,5-diyl) dianiline Monomers. Preparation, Characterization and Thermal, Optical, Electronic and Photovoltaic Properties(ESG, 2012) Jessop, I. A.; Zamora, P. P.; Diaz, F. R.; del Valle, M. A.; Leiva, A.; Cattin, L.; Makha, M.; Bernede, J. C.A new series of polymers, chemically and electrochemically obtained from monomers containing aniline and thiophene moieties, has been prepared. The purpose is to use them as electron donor layers in the fabrication of dual-layer organic solar cells. Both the monomers and the polymers were characterized using techniques such as NMR, FT-IR, cyclic voltammetry, etc. It was found that polymer growth occurred only through aniline unit(s) and not through thiophene unit(s), as might also be expected. Optical and electronic studies revealed that the products displayed properties suitable for use in photovoltaic devices. However, prepared prototypes yields ranged just between 10(-2) and 10(-3).
- ItemPoly(monomethyl itaconate) as subphase stabilizer of maleic anhydride-alt-stearyl methacrylate monolayers at the air-water interface. The study on surface pressure-area isotherms(2001) Gargallo Gómez, Ligia Teresita; Miranda, Beatriz; Leiva, A.; Radić Foschino, Deodato D.
- ItemSitagliptina, un inhibidor de la enzima DPP-IV, aumenta el colesterol plasmático total, altera el perfil de colesterol lipoproteico y disminuye el transporte reverso de colesterol en ratones(2010) Leiva, A.; Varas, P.; Amigo, L.; Contreras-Duarte, S.; Maíz, A.; Rigotti Rivera, AttilioBackground: Insulin and glucagon regúlate the expression of key lipoprotein metabolism enzymes. Dyslipidemia is a significant risk factor for cardiovascular disease, the main cause of death in diabetic patients. Sitagliptine, an inhibitor of type IV dipep-tidil-peptidase (DPP-IV), controlling the metabolism of incretins, is a new hypoglycemic agent used for treatment of type II diabetes. Its effects on lipid metabolism are not clearly defined. Aim: to study the effects of sitagliptine upon parameters of cholesterol metabolism in mice. Methods: C5BL6/J mice were assigned to receive ei-ther a standard diet or one with sitagliptine supplemen-tation (0.6% P/P) for 8 weeks. DPP-IV plasma, total and lipoprotein cholesterol were measured using enzyme methods. Reverse cholesterol transport was evaluated through the peritoneal injection of cholesterol loaded macrophages followed by measurement of plasma and fecall4C labeled cholesterol. Results: compared to controls, sitagliptine treated mice exhibited a 38% decrease in plasma DPP-IV Total plasma cholesterol increased by 60% with a marked increase in HDL cholesterol. Also, an increased HDL cholesterol recovered from plasma along with a 30% decrease in fecal cholesterol was observed Finally, sitagliptine admi-nistration was associated to a decreased LDL and SR-BI hepatic receptors. Conclusión: Sitagliptine administration is associated to increased levéis of plasma cholesterol, mainly the HDL fraction, and decreased reverse cholesterol transport and fecal excretion. This effects seem to be mediated by a decreased expression of SR-BI in the liver. The expected increase in atherosclerosis associated to the atherogenic changes induced by sitagliptine should be the subject for further studies in mice.
- ItemSynthesis and characterization of 4,4 '-(dimethylsilylene)bis(phenyl chloroformate) and 4,4 '-(dimethylgermylene)bis(phenyl chloroformate) and their use in the synthesis of poly(urethanes)(2004) Terraza Inostroza, Claudio; Tagle Domínguez, Luis Hernán; Leiva, A.; Vega, J. C.
- ItemSynthesis and characterization of comb-like poly(esters) containing silicon and or germanium in the main chain(2006) Tagle Domínguez, Luis Hernán; Terraza Inostroza, Claudio; López, L.; Leiva, A.