Hierarchical structure of marine shell biomaterials: biomechanical functionalization of calcite by brachiopods

Biologic structural materials for skeletons or teeth show a hierarchicalarchitecture, where organic macromolecules and mineral substance form ahybrid composite material with its components inter-weaved on manylength scales. On the nanostructure level brachiopods form hybridcomposite mesocrystals of calcite with occluded organic molecules. Onthe microstructure level several types of materials are produced, onwhich the electron back-scatter diffraction (EBSD) technique givesinsight in texture and architecture. We describe the calcitesingle-crystal fiber composite architecture of the secondary layerinvolving organic matrix membranes, the competitive-growth texture ofthe columnar layer and the nanostructuring of the primary layer. In theoverall skeleton the organic biopolymers provide flexibility and tensilestrength while the mineral provides a high elastic modulus, compressivestrength, hardness and resistance to abrasion. The hierarchicalcomposite architecture, from the nanostructure to the macroscopic levelprovides fracture toughness. The morphogenesis of the biomaterial as awhole and of the mineral crystals is guided by the organic matrix andmost probably involves amorphous calcium carbonate (ACC) precursors. Inthis paper we review the hierarchical architecture of rhynchonelliformbrachiopod shells, which is very distinct from mollusk nacre

Mapping of recent brachiopod microstructure: a tool for environmental studies

Shells of brachiopods are excellent archives for environmental reconstructions in the recent and distant past as their microstructure and geochemistry respond to climate and environmental forcings. We studied the morphology and size of the basic structural unit, the secondary layer fibre, of the shells of several extant brachiopod taxa to derive a model correlating microstructural patterns to environmental conditions. Twenty-one adult specimens of six recent brachiopod species adapted to different environmental conditions, from Antarctica, to New Zealand, to the Mediterranean Sea, were chosen for microstructural analysis using SEM, TEM and EBSD. We conclude that: 1) there is no significant difference in the shape and size of the fibres between ventral and dorsal valves, 2) there is an ontogenetic trend in the shape and size of the fibres, as they become larger, wider, and flatter with increasing age. This indicates that the fibrous layer produced in the later stages of growth, which is recommended by the literature to be the best material for geochemical analyses, has a different morphostructure and probably a lower organic content than that produced earlier in life.  In two species of the same genus living in seawater with different temperature and carbonate saturation state, a relationship emerged between the microstructure and environmental conditions. Fibres of the polar L. uva tend to be smaller, rounder and less convex than those of the temperate L. neozelanica, suggesting a relationship between microstructural size, shell organic matter content, ambient seawater temperature and calcite saturation state

Influencia del origen social en el acceso a educación superior. El caso de trabajo social

El propósito de este artículo es presentar los resultados de una investigación que evidencia cómo influye el origen social de los individuos en el acceso y logro de la educación superior y la integración al mercado laboral de un grupo de egresados de la Universidad de Antioquia, pertenecientes al programa de Trabajo Social de la seccional Oriente. En este estudio, se implementó una metodología integrada haciendo uso de la encuesta y la entrevista semiestructurada, con el fin de reconocer las características principales de la experiencia de los egresados y el sentido y significado de la misma. El principal hallazgo es que si bien las condiciones del origen social, caracterizadas por una baja disponibilidad de capital económico y cultural, generan situaciones limitantes para el logro educativo, de igual forma configuran situaciones habilitantes que, en función del aprovechamiento de diferentes recursos que ofrece el entorno, hacen posible la transformación del proyecto de vida de los individuos que se motivan por la educación superior, en respuesta al escenario de oportunidad que constituye la oferta educativa pública de calidad en el territorio

Transformaciones más allá de la política pública de educación superior. El impacto de la formación profesional regionalizada de la Universidad de Antioquia

The purpose of this article is to present part of the results of an investigation that aimed to assess the impacts that access to higher education had on the lives of a group of graduates of the Sociology program, offered in the eastern branch of the Universidad de Antioquia. To achieve this, a study with a complementary approach was carried out, through the implementation of techniques such as the survey and the semi-structured interview, in order to account for the objective and subjective aspects of the experience. The main finding evidenced that professional training allowed the personal fulfillment of the graduates as the foundation of the constitution of their life project; This caused transformations within their family groups and demonstrated that the scope of public policy for higher education goes beyond guaranteeing the population’s access to vocational training.El propósito de este artículo es presentar parte de los resultados de una investigación que tuvo por objetivo valorar los impactos que el acceso a la educación superior propició en la vida de un grupo de egresados del programa de Sociología, ofertado en la seccional oriente de la Universidad de Antioquia. Para alcanzar este objetivo se realizó un estudio con enfoque complementario, mediante la implementación de técnicas como la encuesta y la entrevista semiestructurada, con el fin de dar cuenta de los aspectos objetivos y subjetivos de la experiencia. El principal hallazgo evidenció que la formación profesional permitió la realización personal de los egresados como fundamento de la constitución de su proyecto de vida; ello causó transformaciones al interior de sus grupos familiares y demostró que el alcance de la política pública de educación superior va más allá de garantizar el acceso de la población a la formación profesional

Archival biogenic micro- and nanostructure data analysis: Signatures of diagenetic systems

The present data in brief article provides additional data and information to our research article "Micro- and nanostructures reflect the degree of diagenetic alteration in modern and fossil brachiopod shell calcite: a multi-analytical screening approach (CL, FE-SEM, AFM, EBSD)" [1] (Casella et al.). We present fibre morphology, nano- and microstructure, as well as calcite crystal orientations and textures found in pristine, experimentally altered (hydrothermal and thermal), and diagenetically overprinted brachiopod shells. Combination of the screening tools AFM, FE-SEM, and EBSD allows to observe a significant change in microstructural and textural features with an increasing degree of laboratory based and naturally occurring diagenetic alteration. Amalgamation of neighbouring fibres was observed on the micrometre scale level, whereas progressive decomposition of biopolymers in the shells and fusion of nanoparticulate calcite crystals was detected on the nanometre scale. The presented data in this article and the study described in [1] allows for qualitative information on the degree of diagenetic alteration of fossil archives used for palaeoclimate reconstruction

A Unique Mechanochemical Redox Reaction Yielding Nanostructured Double Perovskite Sr2_{2}FeMoO6_{6} With an Extraordinarily High Degree of Anti-Site Disorder

Strontium ferromolybdate, Sr(2)FeMoO(6), is an important member of the family of double perovskites with the possible technological applications in the field of spintronics and solid oxide fuel cells. Its preparation via a multi-step ceramic route or various wet chemistry-based routes is notoriously difficult. The present work demonstrates that Sr(2)FeMoO(6) can be mechanosynthesized at ambient temperature in air directly from its precursors (SrO, α-Fe, MoO(3)) in the form of nanostructured powders, without the need for solvents and/or calcination under controlled oxygen fugacity. The mechanically induced evolution of the Sr(2)FeMoO(6) phase and the far-from-equilibrium structural state of the reaction product are systematically monitored with XRD and a variety of spectroscopic techniques including Raman spectroscopy, (57)Fe Mössbauer spectroscopy, and X-ray photoelectron spectroscopy. The unique extensive oxidation of iron species (Fe(0) → Fe(3+)) with simultaneous reduction of Mo cations (Mo(6+) → Mo(5+)), occuring during the mechanosynthesis of Sr(2)FeMoO(6), is attributed to the mechanically triggered formation of tiny metallic iron nanoparticles in superparamagnetic state with a large reaction surface and a high oxidation affinity, whose steady presence in the reaction mixture of the milled educts initiates/promotes the swift redox reaction. High-resolution transmission electron microscopy observations reveal that the mechanosynthesized Sr(2)FeMoO(6), even after its moderate thermal treatment at 923 K for 30 min in air, exhibits the nanostructured nature with the average particle size of 21(4) nm. At the short-range scale, the nanostructure of the as-prepared Sr(2)FeMoO(6) is characterized by both, the strongly distorted geometry of the constituent FeO(6) octahedra and the extraordinarily high degree of anti-site disorder. The degree of anti-site disorder ASD = 0.5, derived independently from the present experimental XRD, Mössbauer, and SQUID magnetization data, corresponds to the completely random distribution of Fe(3+) and Mo(5+) cations over the sites of octahedral coordination provided by the double perovskite structure. Moreover, the fully anti-site disordered Sr(2)FeMoO(6) nanoparticles exhibit superparamagnetism with the blocking temperature T (B) = 240 K and the deteriorated effective magnetic moment μ = 0.055 μ (B) per formula unit

Maternal TLR signaling is required for prenatal asthma protection by the nonpathogenic microbe Acinetobacter lwoffii F78

The pre- and postnatal environment may represent a window of opportunity for allergy and asthma prevention, and the hygiene hypothesis implies that microbial agents may play an important role in this regard. Using the cowshed-derived bacterium Acinetobacter lwoffii F78 together with a mouse model of experimental allergic airway inflammation, this study investigated the hygiene hypothesis, maternal (prenatal) microbial exposure, and the involvement of Toll-like receptor (TLR) signaling in prenatal protection from asthma. Maternal intranasal exposure to A. lwoffii F78 protected against the development of experimental asthma in the progeny. Maternally, A. lwoffii F78 exposure resulted in a transient increase in lung and serum proinflammatory cytokine production and up-regulation of lung TLR messenger RNA. Conversely, suppression of TLRs was observed in placental tissue. To investigate further, the functional relevance of maternal TLR signaling was tested in TLR2/3/4/7/9−/− knockout mice. The asthma-preventive effect was completely abolished in heterozygous offspring from A. lwoffii F78–treated TLR2/3/4/7/9−/− homozygous mother mice. Furthermore, the mild local and systemic inflammatory response was also absent in these A. lwoffii F78–exposed mothers. These data establish a direct relationship between maternal bacterial exposures, functional maternal TLR signaling, and asthma protection in the progeny

Decoding Warburg's hypothesis: tumor-related mutations in the mitochondrial respiratory chain

Otto Warburg observed that cancer cells derived their energy from aerobic glycolysis by converting glucose to lactate. This mechanism is in opposition to the higher energy requirements of cancer cells because oxidative phosphorylation (OxPhos) produces more ATP from glucose. Warburg hypothesized that this phenomenon occurs due to the malfunction of mitochondria in cancer cells. The rediscovery of Warburg's hypothesis coincided with the discovery of mitochondrial tumor suppressor genes that may conform to Warburg's hypothesis along with the demonstrated negative impact of HIF-1 on PDH activity and the activation of HIF-1 by oncogenic signals such as activated AKT. This work summarizes the alterations in mitochondrial respiratory chain proteins that have been identified and their involvement in cancer. Also discussed is the fact that most of the mitochondrial mutations have been found in homoplasmy, indicating a positive selection during tumor evolution, thereby supporting their causal role.España, Ministerio de Economía y Competitividad PI12/00137España, Ministerio de Economía y Competitividad PI15/00045España, Ministerio de Economía y Competitividad RD12/0036/0028Unión Europea, Consejería de Ciencia e Innovación CTS-6844Unión Europea, Consejería de Ciencia e Innovación CTS-1848España, Junta de Andalucía,Consejería de Salud PI-0135-2010España, Junta de Andalucía,Consejería de Salud PI-0306-2012España, Junta de Andalucía,Consejería de Salud PI-0096-201