Resolver problemas sociales: hacia una metodología de nodos articuladores (Complexus 11)

Los autores nos comparten sus experiencias y búsquedas, desde sus enfoques teóricos particulares y al mismo tiempo desde un trabajo de interconexión intrauniversitaria para la producción de conocimiento, metodologías y herramientas orientadas a solucionar integralmente problemáticas sociales complejas y con escenarios cambiantes

Caracterización de la super-acidez del carbón sulfatado por espectroscopia

A new acid catalyst based in a carbonaceous solid was functionalized using sulfuric acid as source of –SO.H species. This carbon-based material prepared by the pyrolysis of waste tire rubber was used either as catalyst or as catalytic support. The pyrolysis process was performed with a flow of N. at relatively high temperature to obtain a mesoporous material and after, achieve an effective sulfonation. The sulfonation of char obtained from tire rubber was through direct immersion into concentrated H.SO. under reflux. Chars, original and sulfated, were characterized by several analytic techniques including an elemental analysis. Mainly by Raman and X-ray Photon-electronic spectroscopies. Resultant signals are suggestive of protonic superacidity on sulfonated char, this property being related to the structure of surface sulfonic species.En este trabajo se caracteriza un nuevo material basado en un sólido carbonoso que fue funcionalizado como catalizador super-ácido al usar ácido sulfúrico como fuente de iones sulfonilo –SO.H. Este material carbonoso que se preparó por el proceso de pirólisis aplicado a hule de llanta, puede ser usado como catalizador directamente o bien, como soporte catalítico. El proceso de pirólisis fue realizado con flujo de N. a temperaturas relativamente altas y así obtener un material mesoporoso en base al carbono y que fue sulfonado de forma efectiva. El método de sulfonación del carbón obtenido de hule de llanta fue mediante inmersión en ácido sulfúrico concentrado y a reflujo. Dos muestras de carbón, el original y el sulfonado, fueron caracterizados por medio de diferentes técnicas analíticas, principalmente por las espectroscopías Raman y Fotón-electrónica de rayos-X. Las diversas señales resultantes de estos análisis sugieren super-acidez protónica del carbón sulfonado, siendo tal propiedad relacionada a la estructura de grupos o iones relativos al ácido sulfónico en la superficie del material

Investigating teachers’ use of literacy-infused science strategies: A mixed methods study

Abstract The 2019 science results from the National Assessment of Educational Progress showed that 8th-grade students, especially economically challenged and emergent bilingual students, made few gains in science and reading achievement. Researchers have found that scientific language may be a significant barrier to student comprehension. Researchers have advocated for integrating effective literacy strategies into the science curriculum to assist students in science and reading outcomes. We investigated the enactment of literacy-infused science strategies of a group of participating seventh-grade science teachers in a federally funded project following monthly virtual professional development sessions. Results indicated that teachers self-reported an overall increase in their use of literacy-infused science strategies after participating in monthly literacy-infused virtual professional development

The role of effectors of the activin signalling pathway, activin receptors IIA and IIB, and Smad2, in patterning of tooth development

The synthesis, crystal structures, magnetic behavior, and electron paramagnetic resonance studies of five new Fe^III spin crossover (SCO) complexes are reported. The [Fe^IIIN₅O] coordination core is constituted of the pentadentate ligand bztpen (N₅) and a series of alkoxide anions (ethoxide, propoxide, <i>n</i>-butoxide, isobutoxide, and ethylene glycoxide). The methoxide derivative previously reported by us is also reinvestigated. The six complexes crystallize in the orthorhombic <i>Pbca</i> space group and show similar molecular structures and crystal packing. The coordination octahedron is strongly distorted in both the high- and low-temperature structures. The structural changes upon spin conversion are consistent with those previously observed for [Fe^IIIN₄O₂] SCO complexes of the Schiff base type, except for the Fe–O­(alkoxide) bond distance, which shortens significantly in the high-spin state. Application of the Slichter–Drickamer thermodynamic model to the experimental SCO curves afforded reasonably good simulations with typical enthalpy and entropy variations ranging in the intervals Δ<i>H</i> = 6–13 kJ mol^–1 and Δ<i>S</i> = 40–50 J mol^–1 K^–1, respectively. The estimated values of the cooperativity parameter Γ, found in the interval 0–2.2 kJ mol^–1, were consistent with the nature of the SCO. Electron paramagnetic resonance spectroscopy confirmed the transformation between the high-spin and low-spin states, characterized by signals at <i>g</i> ≈ 4.47 and 2.10, respectively. Electrochemical analysis demonstrated the instability of the Fe­(II) alkoxide derivatives in solution