Role of the Short Distance Order in Glass Reactivity

In 2005, our group described for the first time the structural characterization at the atomic scale of bioactive glasses and the influence of the glasses’ nanostructure in their reactivity in simulated body fluids. In that study, two bioactive sol-gel glasses with composition 80%SiO2–20%CaO and 80%SiO2–17%CaO–3%P2O5 (in mol-%) were characterized by High-Resolution Transmission Electron Microscopy (HRTEM). Such characterization revealed unknown features of the glasses’ structure at the local scale that allowed the understanding of their different in vitro behaviors as a consequence of the presence or absence of P2O5. Since then, the nanostructure of numerous bioactive glasses, including melt-prepared, sol-gel derived, and mesoporous glasses, was investigated by HRTEM, Nuclear Magnetic Resonance (NMR) spectroscopy, Molecular Dynamics (MD) simulations, and other experimental techniques. These studies have shown that although glasses are amorphous solids, a certain type of short distance order, which greatly influences the in vitro and in vivo reactivity, is always present. This paper reviews the most significant advances in the understanding of bioactive glasses that took place in the last years as a result of the growing knowledge of the glasses’ nanostructure

Glasses in bone regeneration: A multiscale issue

3D scaffolds based in mesoporous bioactive glasses (MBGs) are being widely investigated to use in bone tissue engineering (TE) applications. These scaffolds are often obtained by rapid prototyping (RP) and exhibit an array of interconnected pores in a hierarchy of sizes. The ordered mesopore network (around 4 nm in diameter) is optimal for the adsorption and release of bone inductor biomolecules, and the arrangement of macropores over 100 mu m facilitates the bone cell ingrowths and angiogenesis. Nevertheless MBG composition can be varied almost infinitely at the atomic scale by including in the glass network oxides of inorganic elements with a therapeutic action. In this article the synthesis and characterization of MBG scaffolds based on the 80%SiO2-15%CaO-5%P2O5 (in mol-%) glass with substitutions up to 3.5% of Ga2O3 or Ce2O3 or 7.0% of ZnO are revisited. The substituent inclusion and the RP processing slightly decrease the surface area, the pore volume and the mesoporous order as well as their bioactive response in solutions mimicking blood plasma. However, these values still remain useful for bone TE applications. Results exhibiting the bactericide action of MBG scaffolds containing ZnO are also presented. (C) 2015 Elsevier B.V. All rights reserved

EL BANCO DE EMISIÓN DE CHIAPAS, 1902-1908. UNA EXPERIENCIA SINGULAR A FINALES DEL PORFIRIATO

Los estudios económicos y financieros del estado chiapaneco son prácticamente nulos. Aun siendo uno de los factores fundamentales para entender las causas que originaron su rezago y marginación, no se ha puesto énfasis en concebir y exponer que este proceso marcó el destino de la entidad. La finalidad de este artículo es buscar una explicación acerca de los factores que no permitieron que la región, que se había convertido en una proveedora de materias primas y productos agropecuarios para el mercado internacional, pudiera erradicar los rezagos de una sociedad preindustrial que siguió manteniendo vestigios coloniales que fueron suprimidos hasta ya bastante entrado el siglo XX.   Abstract Overview economic studies and financial of the Chiapas State are practically nil. Even as one of the key factors to understand the causes that originated the backwardness and marginalization, has not been an emphasis on design and expose this process marked the destiny of the entity. The purpose of this article is to seek an explanation of the factors that did not allow the region, which had become a supplier of raw materials and agricultural products to the international market, could eradicate the shortcomings of a pre-industrial society that continued to maintain colonial vestiges that were suppressed until now quite entered the 20th century

Tailoring the Structure of Bioactive Glasses: From the Nanoscale to Macroporous Scaffolds

Bioactive glasses have played a very important role in the development of new materials for bone tissue regeneration. The development of new synthesis and manufacturing methods allows the preparation of bioactive glasses with new chemical compositions, nanoscaled features, customized morphologies, and pore architectures. The composition of glasses can be designed at the atomic-molecular level to ensure bioactivity and beneficial effects including capabilities for enhancing osteogenesis and vascularization or to exert bactericide action. Moreover, the glasses can be prepared as mesoporous bioactive glasses, exhibiting ordered arrangements of nanometric pores. Through the control of the microstructure, glasses can be prepared to achieve suitable interactions with living cells. Finally, the scaffolds obtained with bioactive glasses must display interconnected pores over 100 m to make possible bone cell ingrowths and angiogenesis. In this article, the advances in the field of bioactive glasses through the control of the chemical, nanometer scale, microstructural properties, and architectural features are presented and discussed. A detailed control of these four levels of matter organization will allow optimizing the biological response of bioactive glasses when used in bone tissue regeneration

Assessing children’s empathy through a Spanish adaptation of the Basic Empathy Scale: parent’s and child’s report forms

The aim of the current research was to study cognitive and affective empathy in children aged 6–12 years old, and their associations with children’s family environment and social adjustment. For this purpose, we developed the Spanish version of the Basic Empathy Scale (BES), self- and parent-report forms. Factorial analyses confirmed a two-component model of empathy in both self- and parent-report forms. Concordance between parent–child measures of empathy was low for cognitive and affective factors. Analyses of variance on the cognitive and affective components brought a significant effect of age for self-reported cognitive empathy, with older children scoring higher than younger ones. Gender brought out a significant principal effect for self-reported affective empathy, with girls scoring higher than boys. No other main effects were found for age and gender for the rest of the factors analyzed. Children’s empathy was associated with socioeconomic status and other family socialization processes, as well as children’ social behaviors. Overall the new measures provided a coherent view of empathy in middle childhood and early adolescence when measured through self and parent reports, and illustrate the similarity of the validity of the BES in a European-Spanish culture

Lorentz violation in nucleon electromagnetic moments

Yukawa couplings from the Lorentz- and $CPT$-violating Standard Model Extension induce quantum contributions to the magnetic and electric moments of quarks, which are calculated in the present paper. Then we take advantage of the high sensitivity measurements of the proton and neutron electromagnetic moments (EMM), suitable to search for tiny effects of new physics, to constrain coefficients parametrizing Lorentz violation, reaching bounds as restrictive as $10^{-23}$.Comment: 8 pages, 2 figures, 1 tabl

Mesoporous bioglasses enriched with bioactive agents for bone repair, with a special highlight of Maria Vallet-Regi´s contribution

Throughout her impressive scientific career, Prof. María Vallet-Regi opened various research lines aimed at designing new bioceramics, including mesoporous bioactive glasses for bone tissue engineering applica-tions. These bioactive glasses can be considered a spinoff of silica mesoporous materials because they are designed with a similar technical approach. Both materials exhibit ordered mesoporous structures with a very narrow pore size distribution that are achieved by using surfactants during their synthesis. In aqueous solutions the surfactants form mesophases behaving as directing structure agents and after being removed by calcination or extraction the mesoporous bioactive glasses are obtained. The characteristics of these ma-terials made them suitable to be enriched with various osteogenic agents, namely inorganic ions and bio-peptides as well as mesenchymal cells. In the present review, we summarize the evolution of mesoporous bioactive glasses research for bone repair, with a special highlight on the impact of Prof. Maria Val-let-Regi´s contribution to the field