Propuesta innovadora de trabajo práctico de laboratorio de estequiometría

Con el fin de propiciar cambios en los trabajos prácticos de laboratorio (TPL) que se realizan en la cátedra de Complemento de Química General (Ingeniería Química FRAUTN) se propone una estrategia didáctica basada en la resolución de un problema contextualizado enmarcado en el modelo de enseñanza aprendizaje como investigación orientada.Eje 1: Innovación y exploración en cambios de modalidades en cursadasFacultad de Ciencias Exacta

Propuesta innovadora de trabajo práctico de laboratorio de estequiometría

Con el fin de propiciar cambios en los trabajos prácticos de laboratorio (TPL) que se realizan en la cátedra de Complemento de Química General (Ingeniería Química FRAUTN) se propone una estrategia didáctica basada en la resolución de un problema contextualizado enmarcado en el modelo de enseñanza aprendizaje como investigación orientada.Eje 1: Innovación y exploración en cambios de modalidades en cursadasFacultad de Ciencias Exacta

Propuesta innovadora de trabajo práctico de laboratorio de estequiometría

Con el fin de propiciar cambios en los trabajos prácticos de laboratorio (TPL) que se realizan en la cátedra de Complemento de Química General (Ingeniería Química FRAUTN) se propone una estrategia didáctica basada en la resolución de un problema contextualizado enmarcado en el modelo de enseñanza aprendizaje como investigación orientada.Eje 1: Innovación y exploración en cambios de modalidades en cursadasFacultad de Ciencias Exacta

Retinoic acid reduces migration of human breast cancer cells: role of retinoic acid receptor beta

Breast cancer is the most common malignancy in women and the appearance of distant metastases produces the death in 98% of cases. The retinoic acid receptor b (RARb) is not expressed in 50% of invasive breast carcinoma compared with normal tissue and it has been associated with lymph node metastasis. Our hypothesis is that RARb protein participates in the metastatic process. T47D and MCF7 breast cancer cell lines were used to perform viability assay, immunobloting, migration assays, RNA interference and immunofluorescence. Administration of retinoic acid (RA) in breast cancer cells induced RARb gene expression that was greatest after 72 hrs with a concentration 1 lM. High concentrations of RA increased the expression of RARb causing an inhibition of the 60% in cell migration and significantly decreased the expression of migration-related proteins [moesin, c-Src and focal adhesion kinase (FAK)]. The treatment with RARa and RARc agonists did not affect the cell migration. On the contrary, the addition of the selective retinoid RARb-agonist (BMS453) significantly reduced cell migration comparable to RA inhibition. When RARb gene silencing was performed, the RA failed to significantly inhibit migration and resulted ineffective to reduce moesin,c-Src and FAK expressions. RARb is necessary to inhibit migration induced by RA in breast cancer cells modulating the expression of proteins involved in cell migration.Fil: Flamini, Marina Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Gauna, Gisel Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas; ArgentinaFil: Sottile Fleury, Mayra Lis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Nadin, Silvina Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Sanchez, Angel Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Vargas Roig, Laura Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; Argentin

Resilience of Stevia rebaudiana (Bertoni) Bertoni in the Underwater Biospheres of Nemo's Garden®: Adaptation to New Cultivation Systems

The Nemo's Garden® project is an alternative production system for areas with scarce cultivable land but significant presence of water; thus, it is an interesting intervention to address the climate crisis. This work aimed to evaluate the micromorphological, biochemical, and phytochemical characteristics of Stevia rebaudiana (Bertoni) Bertoni grown underwater compared to the terrestrial specimens. The micromorphological analyses, performed on the leaves using light microscopy, fluorescence microscopy, and scanning electron microscopy, evidenced a general uniformity of the trichome morphotype and distribution pattern. The histochemical investigation indicated the simultaneous presence of terpenes and polyphenols in the trichome secreted material from the underwater samples and a prevailing polyphenolic content in the terrestrial specimens; this was also confirmed by biochemical analyses (26.6 mg GAE/g DW). The characterization of non-volatile components, performed using HPLC-MS, showed similar chemical profiles in all the samples, which were characterized by phenolic compounds and steviol glycosides. The volatile compounds, evaluated using HS-SPME coupled with GC-MS, showed sesquiterpene hydrocarbons as the main class in all the analyzed samples (80.1-93.9%). However, the control plants were characterized by a higher content of monoterpene hydrocarbons (12.1%). The underwater biosphere environment did not alter S. rebaudiana micro-morphological characters, although slight qualitative changes were evidenced for the compounds produced as a response to the growth conditions

Representaciones moleculares : Reflexiones sobre su enseñanza

Basados en el lugar de privilegio que tienen las representaciones moleculares en la Química, las dificultades que manifiestan los estudiantes en su comprensión, nos propusimos reflexionar sobre cuestiones derivadas de la problemática inherente a su representación e interpretación, de los aspectos epistemológicos que subyacen a las mismas y de su rol como parte del lenguaje que emplea la Química, así como también sobre estrategias que puedan favorecer su comprensión. Hemos fundamentado el presente trabajo, que tiene la expectativa de obtener conclusiones que permitan propiciar mejoras en la enseñanza y en el aprendizaje, en aportes provenientes del campo de la Filosofía de la Ciencia, la Semiótica, la Psicología Cognitiva y la Didáctica de las CienciasFil: Wainmaier, Cristina Ofelia. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina

Química y medio ambiente : "¿Y si nos ponemos las pilas?" Una propuesta de taller para llevar al aula

En este trabajo se presenta una propuesta didáctica implementada, en el marco de la Semana de la Ciencia y la Tecnología, a través de la modalidad de taller para alumnos de escuelas secundarias referido a pilas y baterías y su impacto en el medio ambiente. Dicha propuesta tiene base en el enfoque Ciencia, Tecnología, Sociedad y Ambiente (CTSA), la cual tiende a favorecer la integración de las dimensiones cognitivas y actitudinales de los estudiantes así como también propender un trabajo interdisciplinario. El creciente consumo de pilas y baterías induce a reflexionar sobre su destino cuando quedan en desuso y el impacto ambiental que su acumulación origina. En este sentido, puede resultar de interés la implementación de esta propuesta de trabajo referida a aspectos generales y efectos en el medio ambiente de pilas y baterías así como también el análisis de las posibles vías de deposición. La escasez de información clara sobre el destino que se le debe dar a las pilas y el desconocimiento generalizado respecto al manejo de residuos peligrosos nos lleva a pensar en la necesidad de promover este tipo de reflexiones en el aul

The influence of ripeness stage and growth area on myrtle-leaved orange (chinotto) peel essential oil composition

Myrtle-leaved orange, or chinotto, is a Chinese lesser-known citrus, nowadays cultivated in all the Mediterranean area of Italy. Its fruits are traditionally used in the confectionary and beverage industries: the former mainly uses the unripe fruits, while the juice of the ripe ones is the core ingredient of the well-known Italian soft drink “Chinotto”. In the present work, the compositions of several accessions of chinotto fruit peel essential oils (EOs) have been analysed by GC-MS: in particular, i) fresh specimens from Savona (Liguria, Italy) at different ripening stages, as well as a dried ripe one; ii) two accessions from Pisa (Tuscany, Italy), of which one native and one transplanted from Savona. A comparison of the analysed samples with literature reported EO compositions has been performed by means of multivariate statistical analysis. The aim was to assess the influence of both the ripening stage and the geographical area of collection on the EO, assessing which factor influenced it the most. The ripening stage influence on the EO composition was found to be less significant compared to the geographical area of growth of the specimens. The statistical analyses, indeed, evidenced a proximity in the compositions obtained from the different ripening stages, whereas greater differences were evidenced for samples at the same ripening phase, but coming from different regions

Changes in biochemical compounds in flesh and peel from Prunus persica fruits grown in Tunisia during two maturation stages.

Plants can synthesize tens to hundreds of thousands of primary and secondary metabolites with diverse biological properties and functions. Fatty acids (FA), phenolic compounds (PC) and volatile compounds (VC) of flesh and peel from three Prunus persica cultivars were evaluated at the Regional Centre of Agricultural Research - Experimental Farm (Sidi Bouzid, Tunisia) during two maturation stages. Palmitic, oleic and linoleic acids are the most abundant FA in Prunus persica cultivars. A genetic effect on FA composition was observed throughout the two sampling periods. Peel was rich in oleic acid with the highest content (31.3% on total FA) in 'O'Henry' cultivar at the commercial ripening date; flesh was rich in linoleic acid with the highest content (44.7% on total FA) in 'Sweet Cap' cultivar at the full ripening date. The monounsaturated/polyunsaturated fatty acids ratios were higher in the commercial ripe than in the full ripe fruits. The analysis of the composition of the VC led to the characterization of 98 different compounds, showing a very high variability among the cultivars. The full ripe fruit (peel and flesh) exhibited the highest total number of terpenoids. Commercial ripe peels were richest in the percentage of hydrocarbons. Comparing cultivars, 'Sweet Cap' cultivar showed the lowest contents of alcohols in peel and flesh of full ripe fruit but highest in peel of commercial ripe fruit, and lowest content of aldehydes in peel and flesh of commercial ripe fruit but highest in peel of ripe ones and the highest ones of lactones. Among PC, the highest contents were observed for o-diphenols and the values showed varietal influence. Total phenols contents decreased during ripening process (p < 0.05) in both peel and flesh tissues, except found for 'Sweet Cap' cultivar. In conclusion, to achieve better FA composition and greater VC and PC production of the peach fruit, P. persica cultivars should be harvested at the commercial ripening date