Nitrogen-based alkaline earth metal compounds: Syntheses, structures and applications

Novel alkaline earth metal aryl substituted silylamides were prepared using alkane (Mg) or salt elimination reactions (Mg, Ca, Sr, and Ba). The salt elimination regime involved the treatment of the alkaline earth metal iodides with two equivalents of the respective potassium amide KNR(SiMe 3 ) (R = 2,6- i -Pr 2 C 6 H 3 and 2,4,6-Me 3 C 6 H 2 ). The organomagnesium source for the alkane elimination was ( n Bu/ s Bu) 2 Mg. Efforts to obtain the beryllium analog resulted in the isolation of a bimetallic lithium-beryllium amido enolate. The alkane elimination route was also extended to the preparation of primary magnesium amides in the absence of donor solvent. A donor-free heteroleptic magnesium dimer was obtained by reacting dibutylmagnesium with one equivalent of the primary amine H2NMes* (Mes* = 2,4,6- t Bu 3 C 6 H 2 ). The synthesis and characterization of novel alkaline earth metal pyrrolates as potential precursors for group 2 containing solid state materials are described. Calcium target molecules were synthesized using two different synthetic schemes: transamination and metallation, involving either the treatment of calcium bis (bis(trimethylsilyl)amide) with two equivalents of 2-dimethylaminomethylpyrrole (2-DMAMP) or the reaction of elemental calcium with two equivalents of 2-DMAMP. Magnesium pyrrolates were synthesized using alkane elimination reactions, involving the treatment of Bu2Mg with two equivalents of 2-DMAMP. The metallation regime was employed to prepare strontium and barium 2-DMAMP derivatives. The 2-DMAMP capacity for σ and π bonding is reflected in the solid state structure of the strontium dimer [Sr(2-DMAMP) 2 THF] 2

Combining bioresorbable polyesters and bioactive glasses: Orthopedic applications of composite implants and bone tissue engineering scaffolds

International audienceThis overview showcases the current state of the art in the fabrication, properties and applications of bioactive glass-polyester composites for dentistry, craniomaxillofacial surgery, orthopedics and bone tissue engineering. The combination of these materials is a successful strategy to simultaneously modulate and optimize the degradation rate, mechanical properties, cell response and osteostimulation of bone substitutes. Two major approaches can be identified: bone regeneration or bone repair. The first is performed using porous scaffolding materials, the second one by dense molded implants. For both strategies, the synthesis, processing and characterization of materials are presented based on a comprehensive review of the available literature. Relevant recent in vitro and in vivo studies are also covered. Current and potential future applications of this interesting family of biocomposites are discussed. The literature search revealed a considerable body of work investigating the biological performance of these composites, evidencing the interest on the topic. In particular, the use of polyester/BG composites is well-studied in terms of material fabrication, as well as characterization of physicochemical and in vitro biological properties. On the other hand, there is much less evidence of translational research efforts. It is apparent that future research will have to focus on the collection of more in vivo and clinical data to broaden the knowledge of the time dependent performance of these materials in realistic condition

100 Cartas para Paulo Freire de quienes pretendemos Enseñar

Realizar un texto colectivo como “100 Cartas para Paule Freire de quienes pretendemos Enseñar”, es un desafío al reunir el aprehender desde el sentido profesional de la educación y con el espíritu de transformación, desde la educación como un espacio endógeno de revolución y exógeno a las comunidades y sociedades, en busca de un sentido de identidad. Hoy desde una crítica decolonial, antirracista, feminista y ecologica en la construcción de un sentido real que busque enfrentar el sistema hegemónico y destructivo que se ha impuesto con explotación, sangre y libertades de nuestro pueblo