El método socrático en los programas educativos actuales: una propuesta de Martha C. Nussbaum

A partir de la propuesta de Martha C. Nussbaum, se analizó la importancia del método socrático aplicado a la educación. Se enfatizó la necesidad de incluir en los programas escolares la enseñanza de las humanidades, las artes y las ciencias sociales a fin de desarrollar en los alumnos habilidades como la crítica, la imaginación, la reflexión, la creatividad y la empatía. Para que estas medidas tengan éxito se propuso que los gobiernos incrementen la inversión en materia educativa, la adecuada formación de los docentes, el aprendizaje de lenguas distintas a la materna y un enfoque plural y multicultural en los cursos

Síntesis, caracterización y aplicaciones de materiales periódicos mesoporosos organosilícicos

A lo largo de esta memoria de tesis se sintetizaron varios materiales periódicos mesoporosos organosilícicos (PMOs) con diferentes fragmentos orgánicos incorporados en su mesoestructura. Para ello se ha seguido varios procedimientos descritos en bibliografía aplicando las modificaciones oportunas para la mejora de sus propiedades texturales y estructurales. Tras su síntesis, se ha realizado una caracterización exhaustiva de cada uno de ellos con diferentes técnicas de caracterización como: DRX, adsorción-desorción de N2, RMN de 13C y 29Si, DRIFT, etc. Todos los materiales han sido sometidos a un estudio sobre su estabilidad térmica e hidrotermal. Además, el material con puentes fenilenos ha sido funcionalizado mediante la incorporación de grupos sulfónicos ácidos, permitiendo así, su posterior uso como catalizador en la reacción de esterificación de ácido acético con etanol. Por último, se ha llevado a cabo la modificación superficial del material con grupos etilidénicos mediante el uso de una de las reacciones más conocidas en química orgánica, la reacción de Diels-Alder. Esto ha permitido incorporados grupos superficiales de gran interés, algunos de los cuales han sido funcionalizados con ácido sulfúrico y fumante, y utilizados como catalizadores ácidos en la reacción de esterificación

Temperature dependent NIR emitting lanthanide-PMO/silica hybrid materials

Two materials - a mesoporous silica (MS) and a periodic mesoporous organosilica (PMO) functionalized with dipyridyl-pyridazine (dppz) units were grafted with near-infrared (NIR) emitting lanthanide (Nd3+, Er3+, Yb3+) complexes in an attempt to obtain hybrid NIR emitting materials. The parent materials: dppz-vSilica and dppz-ePMO were prepared by a hetero Diels-Alder reaction between 3,6-di(2-pyridyl)-1,2,4,5- tetrazine (dptz) and the double bonds of either ethenylene-bridged PMO (ePMO) or vinyl-silica (vSilica) and subsequent oxidation. The dppz-vSilica is reported here for the first time. The prepared lanthanide-PMO/silica hybrid materials were studied in depth for their luminescence properties at room temperature and chosen Nd3+ and Yb3+ samples also at low temperature (as low as 10 K). We show that both the dppz-vSilica and dppz-ePMO materials can be used as "platforms" for obtaining porous materials showing NIR luminescence. To obtain NIR emission these materials can be excited either in the UV or Vis region (into the pi -> pi* transitions of the ligands or directly into the f-f transitions of the Ln(3+) ions). More interestingly, when functionalized with Nd3+ or Yb3+ beta-diketonate complexes these materials showed interesting luminescence properties over a wide temperature range (10-360 K). The Yb3+ materials were investigated for their potential use as ratiometric temperature sensors

Organización del locus del complejo GH-PL en el mono araña (Atelesgeoffroyi)

Tesis (Maestria en Ciencias con Especialidad en Biología Molecular e Ingeniería Genetica) UANLUANLhttp://www.uanl.mx

Designing advanced functional periodic mesoporous organosilicas for biomedical applications

Periodic mesoporous organosilicas (PMOs), reported for the first time in 1999, constitute a new branch of organic-inorganic hybrid materials with high-ordered structures, uniform pore size and homogenous distribution of organic bridges into a silica framework. Unlike conventional mesoporous silicas, these materials offer the possibility to adjust the surface (hydrophilicity/hydrophobicity) and physical properties (morphology, porosity) as well as their mechanical stability through the incorporation of different functional organic moieties in their pore walls. A broad variety of PMOs has been designed for their subsequent application in many fields. More recently, PMOs have attracted growing interest in emerging areas as biology and biomedicine. This review provides a comprehensive overview of the most recent breakthroughs achieved for PMOs in biological and biomedical applications

Facile synthesis of cooperative acid-base catalysts by clicking cysteine and cysteamine on an ethylene-bridged periodic mesoporous organosilica

A periodic mesoporous organosilica (PMO) that contains ethylene bridges was functionalized to obtain a series of cooperative acid-base catalysts. A straightforward, single-step procedure was devised to immobilize cysteine and cysteamine on the support material by means of a photoinitiated thiol-ene click reaction. Likewise, PMO materials capped with hexamethyldisilazane (HMDS) were used to support both compounds. This resulted in different materials in which the amine site was promoted by carboxylic acid groups, surface silanol groups, or both. The catalysts were tested in the aldol reaction of 4-nitrobenzaldehyde and acetone. It was found that silanol groups have a stronger promoting effect on the amine than the carboxylic acid group. The highest turnover frequency (TOF) was obtained for an amine-functionalized material that contained only silanol promoting sites. The loading of the active sites also had a significant effect on the activity of the catalysts, which was rationalized on the basis of a computational study

Zn-Cr layered double hydroxides for photocatalytic transformation of CO2 under visible light irradiation: the effect of the metal ratio and interlayer anion

Carbon dioxide is the main gas responsible for the greenhouse effect. Over the last few years, the research focus of many studies has been to transform CO2 into valuable products (CO, HCOOH, HCHO, CH3OH and CH4), since it would contribute to mitigating global warming and environmental pollution. Layered double hydroxides (LDHs) are two-dimensional materials with high CO2 adsorption capacity and compositional flexibility with potential catalytic properties to be applied in CO2 reduction processes. Herein, Zn-Cr LDH-based materials with different metal ratio and interlayer anions, i.e., chloride (Cl−), graphene quantum dots (GQDs), sodium dodecyl sulfate (SDS) and sodium deoxycholate (SDC), have been prepared by a co-precipitation method and characterized by different techniques. The influence of the interlayer inorganic and organic anions and the metal ratio on the application of Zn-Cr LDHs as catalysts for the photocatalytic CO2 reduction reaction under visible light irradiation is unprecedentedly reported. The catalytic tests have been carried out with Ru(bpy)32+ as photosensitizer (PS) and triethanolamine as sacrificial electron donor (ED) at λ = 450 nm. All LDHs materials exhibited good photocatalytic activity towards CO. Among them, LDH3-SDC showed the best catalytic performance, achieving 10,977 µmol CO g−1 at 24 h under visible light irradiation with a CO selectivity of 88%. This study provides pertinent findings about the modified physicochemical features of Zn-Cr LDHs, such as particle size, surface area and the nature of the interlayer anion, and how they influence the catalytic activity in CO2 photoreduction

Efficient Removal of Nonylphenol Isomers from Water by Use of Organo-Hydrotalcites

The presence of potent organic endocrine-disrupting chemicals (EDCs) in natural aquifers can have adverse impacts on public health and the environment. 4-nonylphenol, one such EDC, can be efficiently removed from water by adsorption onto a clayey material. In this work, we created an effective sorbent for this purpose by using co-precipitation and subsequent ion-exchange to intercalate the organic anion deoxycholate into a Mg/Al hydrotalcite. Intercalating deoxycholate ions increased the organophilicity of the hydrotalcite surface. The solid was used to adsorb 4-nonylphenol at different pollutant concentrations and temperatures. The adsorption process was subjected to a kinetic study. Based on the results, the EDC was adsorbed by chemisorption. In addition, based on the equilibrium isotherms used for the process, the Freundlich model was the most accurate in reproducing the adsorption of 4-nonylphenol onto deoxycholate-intercalated hydrotalcite