Aprendizaje basado en problemas: Una experiencia con alumnos de carreras de Ingeniería

En el nuevo milenio, el conocimiento se caracteriza cada vez más por una integración creativa de la información y el aprendizaje de diversas disciplinas. Los docentes, entonces, necesitan ser conscientes de la necesidad de utilizar nuevas aproximaciones para el manejo del conocimiento y la información. El aprendizaje basado en problemas es un método de enseñanza que se ha usado ampliamente en la educación para el cuidado de la salud y muchas otras profesiones y, más recientemente, en la enseñanza de la ingeniería. Este trabajo relata un intento de usar el aprendizaje basado en problemas en la enseñanza de la metodología de la investigación a estudiantes de ingeniería con el objeto de promover un mayor compromiso en su aprendizaje. Se describen los escenarios propuestos, el proceso seguido por los estudiantes para resolver el problema y los informes realizados acerca de su experiencia. Los resultados recogidos sugieren que la metodología utilizada provee varios desafíos y diferentes oportunidades para el aprendizaje.Knowledge in this new millennium is increasingly characterized by the creative integration of information and learning from diverse disciplines. Educators need to be aware of new approaches of dealing with knowledge and information where problems can be used innovatively in pedagogies. Problem-based learning (PBL) is an inquiry-based pedagogy that has been widely used in health care education and many other professions. Recent years have seen the emergence of its use in engineer education. This paper reports an attempt to use PBL to teach the elements of the research methodology to engineering students. The intention was to provide more engaging pedagogy. The scenarios and related materials, processes and reflective writing developed by students are analyzed. The findings suggest that PBL methodology provides a wide range of challenging issues and learning opportunities.Fil: Okulik, Nora Beatriz. Universidad Nacional del Nordeste. Facultad de Agroindustrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentin

Theoretical studies on the structure and spectroscopic properties of pseudohalides

Pseudohalogen-containing compounds have attracted significant interest among nonmetal chemists and theorists, not only owing to their potential use in various fields but also due to difficulties in their experimental preparation and characterization. Since its introduction in 1925, the pseudohalide principle has been used extensively and, therefore, a remarkable progress has been made in the experimental and theoretical research on the compounds of this kind. In this work, we review studies on structural investigations and theoretical characterizations of several pseudohalide-containing compounds in order to contribute to better understanding of the chemistry of many such species.Centro de Química InorgánicaInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Topological properties of some PhSeX compounds

A theoretical study on the series of compounds PhSeX where Ph=phenyl, Se=selenium and X=Cl, Br, I, CN or SCN, is reported and compared with previously reported experimental data. The molecular geometry for these PhSeX compounds was studied at the DFT/B3LYP level of calculation by means of the 6-311G(d,p) basis set. The equilibrium structures of the molecules were dependent on the method employed to compare the known solid structures. A topological study of the calculated PhSeX species, based on the AIM theory, was carried out to gain a deeper insight into the bonding nature and to find an explanation for the structural diversity exhibited by these PhSeX compounds. The results reported herein illustrate the subtle differences in the solid-state structures of PhSeX compounds.Fil: Okulik, Nora Beatriz. Universidad Nacional del Chaco Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Jubert, Alicia Haydee. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Castro, Eduardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

Development and characterization of benznidazole nano- and microparticles: A new tool for pediatric treatment of Chagas disease?

Benznidazole (BNZ) is the drug of choice for the treatment of Chagas disease in many countries. However, its low water solubility produces low and/or variable oral bioavailability. Thus, the aim of this work was to formulate micro- and nanoparticles based on Eudragit® RS PO and Eudragit® RL PO as a convenient approach to increase the dissolution rate of BNZ. The microparticles were obtained by means of spray-drying process while the nanoparticles were prepared through the nanoprecipitation technique and further freeze-drying. The results indicated that nanoparticles were obtained in 86% yield while microparticles were obtained in 68% yield. In both cases, the encapsulation efficiency of particles was greater than 78% while drug loading capacity was nearly 24% w/w and 18% w/w, after spray-drying and freeze-drying procedures, respectively. Images of scanning electron microscopy showed that the particles obtained by spray-drying and freeze-drying were in the micrometer and nanometer scale, respectively. FT-IR spectra of BNZ-loaded particles obtained by both methods showed characteristic bands of BNZ confirming that part of drug remained on their surface. Thermal analysis revealed that the drug crystallinity after both methods decreased. Physical stability evaluation of the nanoparticles confirmed that Pluronic® F68 was suitable to keep the particles size in a range of 300 nm after 70 days storage at 4 ± 2 °C. In-vitro release studies showed increased dissolution rate of drug from the particles obtained by both methods respect to untreated BNZ. The kinetics of drug release in acid media followed the Higuchi kinetics indicating drug diffusion mechanism from particles.Fil: Seremeta, Katia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Chaco Austral. Departamento de Ciencias Básicas y Aplicadas; ArgentinaFil: Arrua, Eva Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Okulik, Nora Beatriz. Universidad Nacional del Chaco Austral. Departamento de Ciencias Básicas y Aplicadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Salomon, Claudio Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin

Improved QSAR Analysis of the Toxicity of Aliphatic Carboxylic Acids

The results of a QSPR study of the toxicity of carboxylic acids in aqueous solution are reported. The molecular set comprises 35 carboxylic acids with the corresponding pK; a values in water. The set of molecular and topological parameters includes electrotopological state of the carboxy and methyl groups, molar refractivity, refractive index, n-octanol-water partition coefficient logKo/w, surface tension, and polarizability. Quite reasonable estimates are obtained, which improve the results of previous theoretical calculations.Centro de Química InorgánicaUniversidad Nacional del Nordest

m -Cresol methylation: Role of internal and external acid sites in the product distribution

The effect of the porous structure and the role of internal and external acid sites in product distribution in gas-phase alkylation of m-cresol with methanol were studied on zeolites HBEA, HZSM5 and HMCM22. Catalysts were characterized by N2 physisorption and FTIR of adsorbed pyridine. Trimethylated product formation was inhibited in narrower pore size zeolites (HMCM22 and HZSM5) and a preferential selectivity to smallest dimethylphenol isomer (2,5-dimethylphenol) was observed. The selectivity to 2,5-dimethylphenol on HMCM22 reached a value of 82% after suppressing the acid sites of the external cavities and pore mouth using 2,4-dimethylquinoline, which is a basic molecule too bulky to diffuse through the narrow pores of these zeolites.Fil: Acevedo, Mauro Dino. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Chaco Austral; ArgentinaFil: Montañez Valencia, Mardelly Kateryne. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Okulik, Nora Beatriz. Universidad Nacional del Chaco Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sad, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Padro, Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentin

Nanocarriers for effective delivery of benznidazole and nifurtimox in the treatment of chagas disease: A review

Neglected tropical diseases (NTDs) constitute a group of infectious diseases prevalent in countries with tropical and subtropical climate that affect the poorest individuals and produce high chronic disability associated with serious problems for the health system and socioeconomic development. Chagas disease or American trypanosomiasis is included on the NTDs list. However, even though this disease affects more than 10 million people, mostly in Latin America, causing the death of over 10,000 people every year, only two drugs are approved for its treatment, benznidazole and nifurtimox. These antiparasitic agents were developed almost half a century ago and present several biopharmaceutical disadvantages such as low aqueous solubility and permeability limiting their bioavailability. In addition, both therapeutic agents are available only as tablets and a liquid pediatric formulation is still lacking. Therefore, novel pharmaceutical strategies to optimize the pharmacotherapy of Chagas disease are urgently required. In this regard, nanotechnological approaches may be a crucial alternative for the delivery of both drugs ensuring an effective pharmacotherapy although the successful bench-to-bedside translation remains a major challenge. The present work reviews in detail the formulation and in-vitro/in-vivo analysis of different nanoformulations of nifurtimox and benznidazole in order to enhance their solubility, dissolution, bioavailability and trypanocidal activity.Fil: Arrua, Eva Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Farmacia; ArgentinaFil: Seremeta, Katia Pamela. Universidad Nacional del Chaco Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Bedogni, Giselle Rocio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Farmacia; ArgentinaFil: Okulik, Nora Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Chaco Austral; ArgentinaFil: Salomon, Claudio Javier. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Alquilación de m-cresol con 2-propanol sobre catalizadores ácidos

En este trabajo se estudió la reacción de alquilación de m-cresol con 2-propanol (IPA) en fase gas sobre catalizadores sólidos ácidos. La acidez de los catalizadores se determinó mediante FTIR de piridina y TPD de NH3. La influencia de las características de los catalizadores se estudió utilizando HBEA, ZnY y HZSM5. Usando HBEA se observó una disminución de la conversión al aumentar la temperatura ya sea por aumento de desactivación o por limitación termodinámica. Variando el tiempo de contacto se pudo concluir que el 2-isopropil-5-metilfenol (timol) es un producto primario que se forma mayoritariamente a bajas conversiones (y en menor medida se forma el 4-isopropil-3-metilfenol) (4I3MF) y se convierte al isómero más estable 3-isopropil-5-metilfenol (3I5MF) al aumentar la conversión. La conversión de m-cresol sobre ZnY es menor que sobre HBEA, a pesar de que la zeolita ZnY tiene mayor acidez que HBEA indicando que los sitios ácidos de Lewis fuertes que posee este material serían menos activos en esta reacción. HZSM5 fue muy poco activa lo que puede deberse a limitaciones difusivas. Probablemente debido a la baja conversión, la selectividad a timol fue elevada (80%) sobre este catalizador. Los productos de O-alquilación no se formaron sobre ningún catalizador ni condición empleada.Fil: Acevedo, Mauro Dino. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Chaco Austral; ArgentinaFil: Okulik, Nora Beatriz. Universidad Nacional del Chaco Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Padro, Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaXXI Congreso Argentino de CatálisisSANTA FEArgentinaInstituto de Desarrollo Tecnológico para la Industria QuímicaInstituto de Investigaciones en Catálisis y Petroquímic

Apigenin oxidovanadium(IV) cation interactions : Synthesis, spectral, bovine serum albumin binding, antioxidant and anticancer studies

Continuing and expanding our previous work on flavonoid oxidovanadium(IV) (VO) metal complexes as possible anti-cancer agents, the VOapigenin compound was synthesized and characterized. An “acetylacetone-like” coordination through the C=O and O moieties of the ligand to the metal center with one apigenin ligand per metal ion was assumed using different spectroscopies and elemental analysis as well as thermal measurements. The vibrational experimental spectrum of VOapigenin was supported by theoretical calculations. According to the structure of the flavonoid it exerted mild antioxidant properties that were enhanced by metal coordination. The compounds showed moderate anticancer activity on lung A549 and cervix HeLa cancer cell lines, displaying an incubation time dependent behavior. Cellular increase of reactive oxygen species (ROS) and glutathione depletion have been measured upon incubation with the compounds. These cell killing activities were reverted when natural antioxidants were incubated with the compounds and the addition of the antioxidant agent Nacetylcysteine generated depletion of the cellular ROS levels. Therefore, a stress oxidative mechanism of action has been assumed. Moreover, the compounds showed no toxicity against Artemia salina and were not mutagenic. Both apigenin and the complex could be transported and stored by bovine serum albumin with similar binding constants and mechanisms than other VOflavonoid complexes.Centro de Química Inorgánic

Topological properties of some PhSeX compounds

A theoretical study on the series of compounds “PhSeX”, where Ph=phenyl, Se=selenium and X=Cl, Br, I, CN or SCN, is reported and compared with previously reported experimental data. The molecular geometry for these PhSeX compounds was studied at the DFT/B3LYP level of calculation by means of the 6-311G(d,p) basis set. The equilibrium structures of the molecules were dependent on the method employed to compare the known solid structures. A topological study of the calculated PhSeX species, based on the AIM theory, was carried out to gain a deeper insight into the bonding nature and to find an explanation for the structural diversity exhibited by these PhSeX compounds. The results reported herein illustrate the subtle differences in the solid-state structures of PhSeX compounds.Facultad de Ciencias ExactasCentro de Química InorgánicaInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicada