A synchrotron study of Na2.27Ho7.73(SiO4)6O0.72

A well crystallized powder sample of sodium holmium orthosilicate oxyapatite, Na2.27Ho7.73(SiO4)6O0.72, was obtained after mechanical milling and thermal treatment at 1123 K. Crystal structure analysis was performed from the results of Rietveld refinement of the synchrotron diffraction data. As in other rare-earth orthosilicate apatites, sodium cations appear located sharing with holmium the 4f Wyckoff position at the center of a tricapped trigonal prism. In its turn, holmium almost fully occupies the 6h position at the center of a seven-coordinated penta­gonal bipyramid. A small quantity of Na atoms was found at this site. No vacancies are present in the two independent crystallographic sites available for Ho and Na atoms

Revealing the remarkable structural diversity of the alkali metal transfer agents of the trans-calix[2]benzene[2]pyrrolidide ligand

Excellent reagents for transferring their heterocalix[4]arene ligand to f-block organometallic complexes, lithium, sodium and potassium trans-calix[2]benzene[2]pyrrolidides have been found to adopt a fascinating series of structures in their own right

Enhanced removal of a pesticides mixture by single cultures and consortia of free and immobilized Streptomyces strains

Pesticides are normally used to control specific pests and to increase the productivity in crops; as a result, soils are contaminated with mixtures of pesticides. In this work, the ability of Streptomyces strains (either as pure or mixed cultures) to remove pentachlorophenol and chlorpyrifos was studied. The antagonism among the strains and their tolerance to the toxic mixture was evaluated. Results revealed that the strains did not have any antagonistic effects and showed tolerance against the pesticides mixture. In fact, the growth of mixed cultures was significantly higher than in pure cultures. Moreover, a pure culture (Streptomyces sp. A5) and a quadruple culture had the highest pentachlorophenol removal percentages (10.6% and 10.1%, resp.),while Streptomyces sp.M7 presented the best chlorpyrifos removal (99.2%).Mixed culture of all Streptomyces spp. when assayed either as free or immobilized cells showed chlorpyrifos removal percentages of 40.17% and 71.05%, respectively, and for pentachlorophenol 5.24% and 14.72%, respectively, suggesting better removal of both pesticides by using immobilized cells. These results reveal that environments contaminated with mixtures of xenobiotics could be successfully cleaned up by using either free or immobilized cultures of Streptomyces, through in situ or ex situ remediation techniques.Fil: Fuentes, María Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Briceño, Gabriela E.. Universidad de la Frontera; Chile;Fil: Sáez, Juliana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Benimeli, Claudia Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tucumán. Unidad de Administración Territorial; Argentina. Universidad del Norte Santo Tomás de Aquino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Diez, Maria Cecilia. Universidad de la Frontera; Chile;Fil: Amoroso, Maria Julia del R.. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad del Norte Santo Tomás de Aquino; Argentin

Systematic Bias in Helioseismic Measurements of Meridional Circulation Arising from Nonlocal Averaging Kernels

Meridional circulation in the solar convection zone plays a profound role in regulating the interior dynamics of the Sun and its magnetism. While it is well accepted that meridional flows move from the equator towards the poles at the Sun's surface, helioseismic observations have yet to provide a definitive answer for the depth at which those flows return to the equator, or the number of circulation cells in depth. In this work, we investigate whether the discrepancies regarding the nature of the return flow are intrinsic to how helioseismic observations are made. We examine the seismic signature of possible meridional flow profiles by convolving time-distance averaging kernels with the mean flows obtained from 3-D hydrodynamic simulations of the solar convection zone. At mid and high latitudes, we find that weak flow structures in the deeper regions of the convection zone can be strongly obscured by signal from the much stronger surface flows. This contamination is the result of extended side lobes in the averaging kernels and generates a spurious equatorward signal of 2--3 m s$^{-1}$ at those latitudes, and at $\approx 70~\mathrm{Mm}$ depth. At low latitudes, however, the flows in the simulations tend to be stronger and multiple cells across the shell depth can produce a sufficiently strong seismic signal to survive the convolution process. The signal associated with the deep equatorward return flow in the Sun is expected to be weak and in the same sense as the contamination from the surface. Hence, the return flow needs to exceed $\sim 2$--$3~ \mathrm{m~s^{-1}}$ in magnitude for reported detections to be considered significant.Comment: Submitted to AAS Journal

El Joc de rol com a eina d’aprenentatge en assignatures de ciència i tecnologia de materials

La incorporació de les universitats europees a l'EHEA ha conduit a la remodelació de plans d'estudi i també, a la redefinició de protagonismes en el procés d'ensenyament-aprenentatge en l'àmbit universitari. Així, el paradigma de Bolònia ha contribuït a que, progressivament, s'hagin incorporat competències, processos d'avaluació continuada, d'autoavaluació i de coavaluació, que afavoreixen que l'estudiantat formi part del propi procés d'aprenentatge. Paral•lelament, en els darrers anys, la diversitat de formats disponibles per compartir informació (text, imatge, simulacions, vídeo) ha ajudat a que la pràctica docent pugui ser més àgil i, per tant, ha contribuït a afavorir la participació de l'estudiantat. En l'àmbit de materials, les tecnologies de comunicació han ajudat a visualitzar processos, a gestionar bases de dades de selecció de materials i a optimitzar les quotes d'atenció en l'activitat docent universitària. En aquest escenari, el projecte RIMA (Recerca i Innovació en Metodologies d'aprenentatge) neix amb la voluntat de potenciar les activitats desenvolupades pels Grups d'Interès (Communities of Practice) que s'han creat a la UPC. Entre ells, el grup d'Innovació Docent en Materials, GidMAT, proporciona un espai de comunió i compartició d'experiències així com un foro de debat entre professionals de la docència de materials. En aquest treball es proposa una activitat de joc de rol com a activitat pràctica de materials en l'àmbit de l'enginyeria. La interacció professorat-alumnat és imprescindible i la metodologia proposada garanteix una constant comunicació i un feed-back eficaç que possibiliti l'avaluació continua de les assignatures de tecnologia de materials.Peer Reviewe

Root ABA and H+-ATPase are key players in the root and shoot growth-promoting action of humic acids

Although the ability of humic (HA) and fulvic acids (FA) to improve plant growth has been demonstrated, knowledge about the mechanisms responsible for the direct effects of HA and FA on the promotion of plant growth is scarce and fragmentary. Our study investigated the causal role of both root PM H+-ATPase activity and ABA in the SHA-promoting action on both root and shoot growth. The involvement of these processes in the regulation of shoot cytokinin concentration and activity was also studied. Our aim was to integrate such plant responses for providing new insights to the current model on the mode of action of HA for promoting root and shoot growth. Experiments employing specific inhibitors and using Cucumis sativus L. plants show that both the root PM H+-ATPase activity and root ABA play a crucial role in the root growth-promoting action of SHA. With regard to the HA-promoting effects on shoot growth, two pathways of events triggered by the interaction of SHA with plant roots are essential for the increase in root PM H+-ATPase activity-which also mediates an increase in cytokinin concentration and action in the shoot-and the ABA-mediated increase in hydraulic conductivity (Lp(r))

Selective Fractionation And Isolation Of Allelopathic Compounds From Helianthus Annuus L. Leaves By Means Of High-Pressure Techniques

The allelopathic potential of Helianthus annuus L. leaves was study based on bio-directed chemical fractionation approach. Aerial parts of H. annuus were extracted by means of SFE using supercritical carbon dioxide (scCO2) and ESE using CO2+50% EtOH/H2O (varying ethanol in water from 0 to 100%). Extractions were carried out at 400 bar, 55 °C, 20 g/min and for 4 h. Then, extracts were fractionated in three separators at the following conditions: S1: 200 bar/45 °C; S2: 90 bar/40 °C; and S3: 1 atm/30 °C. ESE obtained higher overall yields than scCO2 and the use of water as cosolvent (CO2+50% H2O) resulted in a S3 fraction free from chlorophylls and rich in bioactive compounds. 14 compounds, including fatty acids, terpenes, flavonoids and heliannuols, were isolated from this fraction. After performing the bioassay on pure compounds, heliannuol D, tambulin, pinoresinol and sesquiterpene 10-oxo-isodauc-3-en-15-al showed the most effective inhibitor profiles

Áreas de riesgo agroclimático para cuatro rotaciones de cultivos de la región oriental agropecuaria de La Pampa (Argentina)

Climatic risks imply the probability of occurrence of extreme weather conditions, events that can threaten nature and human activities with a particular pattern of low frequency. They are termed agroclimatic risks when affecting farm production. The aim of this work was to assess an index of agroclimatic risk (ACR), based on the study of soil water climatology and simulation of different crop rotation schedules. The ACR index scoring was based on a scale of values running from 0 (minimum risk) to 1 (maximum risk). Four crop rotation schedules, under conditions of dry-land farming, were tested in 21 sites all over the Eastern region of La Pampa province: fallow land - wheat crop (FL-WC), lucerne pasture - wheat crop (LP-WC), fallow land - sunflower crop (FL-SC) and winter annual grass pasture - sunflower crop (WP-SC). Maps, generated with information involving the application for decades of FL-WC, LP-WC, FL-SC and WP-SC rotation schedules, showed the yearly occurrence of partial or absolute droughts during the warm semester. Rotation Schedule FL-WC exhibited lower ACR values (0.1 to 0.4) than LP-WC (0.1 to 0.6), FL-SC (0.4 to 0.5) and WP-SC (0.4 to 0.5 ). In all cases, ACR index took higher values for the Centraland South-Eastern regions than the North-Eastern region of La Pampa province.Los riesgos climáticos son, en esencia, la probabilidad de ocurrencia de eventos de baja frecuencia que más tarde o más temprano terminan desarrollándose, guiados por su particular periodicidad. Estos riesgos se convierten en agroclimáticos cuando afectan a la producción agropecuaria. En el presente trabajo se calculó un índice de riesgo agroclimático (RAC) basado en el estudio de la climatología del agua del suelo simulando diferentes planteos rotacionales. El RAC toma valores entre 0 (riesgo mínimo) y 1 (riesgo máximo). Se utilizaron cuatro planteos rotacionales en secano: barbecho-trigo, alfalfa-trigo, barbecho-girasol y verdeo de invierno-girasol en veintiuna localidades de la región oriental agropecuaria de La Pampa. Los mapas muestran que en las cuatro rotaciones analizadas, durante todas las décadas que involucra cada planteo, se presentaron condiciones de sequía condicional o absoluta dentro de la época del año correspondiente al semestre cálido. La rotación barbecho-trigo presenta menor riesgo climático (RAC: 0.1 a 0.4) que alfalfa trigo (RAC: 0.1 a 0.6), barbecho-girasol (RAC: 0.4 a 0.5) y verdeo de invierno-girasol (RAC: 0.4 a 0.5). Los planteos rotacionales que involucran a un cultivo anual invernal (trigo) y los que consideran un cultivo anual estival (girasol) presentan mayor riesgo agroclimático de deficiencia hídrica en la zona centro-sur de la región agropecuaria pampeana que en la del nor-noreste

Sulfation of L-Selectin Ligands by an HEV-Restricted Sulfotransferase Regulates Lymphocyte Homing to Lymph Nodes

AbstractLymphocytes home to lymph nodes, using L-selectin to bind specific ligands on high endothelial venules (HEV). In vitro studies implicate GlcNAc-6-sulfate as an essential posttranslational modification for ligand activity. Here, we show that genetic deletion of HEC-GlcNAc6ST, a sulfotransferase that is highly restricted to HEV, results in the loss of the binding of recombinant L-selectin to the luminal aspect of HEV, elimination of lymphocyte binding in vitro, and markedly reduced in vivo homing. Reactivity with MECA 79, an adhesion-blocking mAb that stains HEV in lymph nodes and vessels in chronic inflammatory sites, is also lost from the luminal aspects of HEV. These results establish a critical role for HEC-GlcNAc6ST in lymphocyte trafficking and suggest it as an important therapeutic target