Formation Mechanism of Maghemite Nanoflowers Synthesized by a Polyol-Mediated Process

Magnetic nanoparticles are being developed as structural and functional materials for use in diverse areas, including biomedical applications. Here, we report the synthesis of maghemite (¿-Fe2O3) nanoparticles with distinct morphologies: single-core and multicore, including hollow spheres and nanoflowers, prepared by the polyol process. We have used sodium acetate to control the nucleation and assembly process to obtain the different particle morphologies. Moreover, from samples obtained at different time steps during the synthesis, we have elucidated the formation mechanism of the nanoflowers: the initial phases of the reaction present a lepidocrocite (¿-FeOOH) structure, which suffers a fast dehydroxylation, transforming to an intermediate "undescribed" phase, possibly a partly dehydroxylated lepidocrocite, which after some incubation time evolves to maghemite nanoflowers. Once the nanoflowers have been formed, a crystallization process takes place, where the ¿-Fe2O3 crystallites within the nanoflowers grow in size (from ~11 to 23 nm), but the particle size of the flower remains essentially unchanged (~60 nm). Samples with different morphologies were coated with citric acid and their heating capacity in an alternating magnetic field was evaluated. We observe that nanoflowers with large cores (23 nm, controlled by annealing) densely packed (tuned by low NaAc concentration) offer 5 times enhanced heating capacity compared to that of the nanoflowers with smaller core sizes (15 nm), 4 times enhanced heating effect compared to that of the hollow spheres, and 1.5 times enhanced heating effect compared to that of single-core nanoparticles (36 nm) used in this work

Ancient xenocrystic zircon in young volcanic rocks of the southern Lesser Antilles island arc

The Lesser Antilles arc is one of the best global examples in which to examine the effects of the involvement of subducted sediment and crustal assimilation in the generation of arc crust. Most of the zircon recovered in our study of igneous and volcaniclastic rocks from Grenada and Carriacou (part of the Grenadines chain) is younger than 2 Ma. Within some late Paleogene to Neogene (~ 34–0.2 Ma) lavas and volcaniclastic sediments however, there are Paleozoic to Paleoarchean (~ 250–3469 Ma) xenocrysts, and Late Jurassic to Precambrian zircon (~ 158–2667 Ma) are found in beach and river sands. The trace element characteristics of zircon clearly differentiate between different types of magmas generated in the southern Lesser Antilles through time. The zircon population from the younger arc (Miocene, ~ 22–19 Ma, to Present) has minor negative Eu anomalies, well-defined positive Ce anomalies, and a marked enrichment in heavy rare earth elements (HREE), consistent with crystallization from very oxidized magmas in which Eu2 + was in low abundance. In contrast, zircon from the older arc (Eocene to mid-Oligocene, ~ 30–28 Ma) has two different REE patterns: 1) slight enrichment in the light (L)REE, small to absent Ce anomalies, and negative Eu anomalies and 2) enriched High (H)REE, positive Ce anomalies and negative Eu anomalies (a similar pattern is observed in the xenocrystic zircon population). The combination of positive Ce and negative Eu anomalies in the zircon population of the older arc indicates crystallization from magmas that were variably, but considerably less oxidized than those of the younger arc. All the igneous zircon has positive εHf(t), reflecting derivation from a predominantly juvenile mantle source. However, the εHf(t) values vary significantly within samples, reflecting considerable Hf isotopic heterogeneity in the source. The presence of xenocrystic zircon in the southern Lesser Antilles is evidence for the assimilation of intra-arc crustal sediments and/or the recycling and incorporation of sediments into the magma sources in the mantle wedge. Most likely however, primitive magmas stalling and fractionating during their ascent through the Antilles crust entrained ancient zircon. This is evidence by the geochemistry of the study samples, which is inconsistent with any involvement of partially melted subducted sediment. Paleogeographic reconstructions show that the old zircon could derive from distant regions such as the Eastern Andean Cordillera of Colombia, the Merida Andes, and the northern Venezuela coastal ranges, transported for example by the Proto-Maracaibo River precursor of the Orinoco River.This study was supported by Deutsche Forschungsgemeinschaft (DFG) grants KR590/85-1 to AK and RO4174/2-1 to YRA, and Spanish MINECO grants CGL2015-65824 and CGL2012-36263 and University of Granada research program (CIC) to AGC and CLC. This research also received support from the SYNTHESYS Project (http://www.synthesys.info/) which is financed by the European Community Research Infrastructure Action under the FP7 “Capacities” Program, the Intra-University Research Support Program of Mainz University (Universitätsinterne Forschungsförderung (FoFö)

Remediación de suelos contaminados con hidrocarburos empleando sustancias húmicas de vermicomposta

La biorremediación utilizando sustancias húmicas es una de las técnicas recientes y prometedoras para la restauración de suelos contaminados por hidrocarburos, pero existe poca información sobre su comportamiento en los diversos tipos de suelo. Por estas razones, esta investigación tuvo como objetivo evaluar la remoción de hidrocarburos totales del petróleo o HTP en tres suelos con diferentes texturas (S1, S2 y S3) y tratados con enmiendas orgánicas de vermicomposta (cascarillas de cacao, Theobroma cacao; arroz, Oriza sativa; bagazo de caña, Saccharum officinarum; estiércol de vaca) y sustancias húmicas comerciales (humato de potasio). Se planteó un diseño experimental multifactorial aleatorio (3 × 3 × 2), constituido por tipo de suelo, enmienda orgánica (sin vermicomposta, con vermicomposta orgánica, con sustancias húmicas comerciales), y carga microbiana (con microorganismos, sin microorganismos). Los resultados fueron analizados mediante las pruebas ANOVA-Tukey en el programa Statgraphics Centurion TM V.18 (α = 0.05) con el fin de evaluar diferencias significativas entre los tratamientos. Los resultados muestran que S2 con vermicomposta orgánica tuvo la mayor remoción (86% de HTP) luego de 60 días de incubación, en comparación con el tratamiento con sustancias húmicas comerciales, relacionándose con la baja biodisponibilidad de microorganismos. Este comportamiento también se observó en S3, el cual tuvo un porcentaje de remoción de HTP de 77.52 y 63.4%. Finalmente, la tasa de crecimiento celular fue mejor en S2 con sustancias húmicas comerciales. Se obtuvo un crecimiento promedio de 94×104 UFC g-1 de suelo durante los 60 días de evaluación del experimento, y un máximo de 98×105 UFC g-1 de suelo a los 45 días de tratamiento. Se concluye que el uso de vermicomposta es adecuada para suelos arcillosos, ya que las tasas de degradación son mayores en ellos. Además, representan una alternativa de menor costo que los tratamientos sintéticos y de revalorización de residuos orgánicos

Dissecting the long-term emission behaviour of the BL Lac object Mrk 421

We report on long-term multiwavelengthmonitoring of blazar Mrk 421 by the GLAST-AGILE Support Program of the Whole Earth Blazar Telescope (GASP-WEBT) collaboration and Steward Observatory, and by the Swift and Fermi satellites. We study the source behaviour in the period 2007–2015, characterized by several extreme flares. The ratio between the optical, X-ray and γ -ray fluxes is very variable. The γ -ray flux variations show a fair correlation with the optical ones starting from 2012.We analyse spectropolarimetric data and find wavelengthdependence of the polarization degree (P), which is compatible with the presence of the host galaxy, and no wavelength dependence of the electric vector polarization angle (EVPA). Optical polarimetry shows a lack of simple correlation between P and flux and wide rotations of the EVPA.We build broad-band spectral energy distributions with simultaneous near-infrared and optical data from the GASP-WEBT and ultraviolet and X-ray data from the Swift satellite. They show strong variability in both flux and X-ray spectral shape and suggest a shift of the synchrotron peak up to a factor of ∼50 in frequency. The interpretation of the flux and spectral variability is compatible with jet models including at least two emitting regions that can change their orientation with respect to the line of sight.http://10.0.4.69/mnras/stx2185Accepted manuscrip

Identificación genética de bacterias ácido lácticas nativas en leche cruda de vaca y queso Poro artesanal

El sabor y aroma de los quesos se debe a la diversidad de compuestos producidos por los microorganismos, que actúan durante el cuajado de la leche y maduración de los quesos. El objetivo aquí fue, identificar bacterias ácido lácticas en leche cruda de vaca y el queso Poro artesanal que se elabora en Tabasco, México. El aislamiento de las bacterias lácticas (BAL) se realizó sobre agar MRS, LBS y M17. Las cepas aisladas fueron caracterizadas por morfología, tinción de Gram, pruebas bioquímicas y crecimiento a diferentes concentraciones de cloruro de sodio (NaCl) y pH. La identificación genética inició con la extracción del ADN, amplificación del gen ARN ribosomal 16S con cebadores universales para bacterias. Las amplificaciones resultantes fueron secuenciadas en un laboratorio externo. Se identificaron 31 BAL, donde se observó Lactobacillus rhamnosus (38,71%), Lactobacillus fermentum (29,03%), Lactobacillus plantarum (6,45%) en muestras de leche y queso. También se identificó Enterococcus durans (6,45%) en leche y Lactobacillus farciminis (3,23%) en queso Poro. Todas reportadas por sus características biotecnológicas, tal como cultivos iniciadores. Estos resultados serán la base para formular y estabilizar un cultivo iniciador, que pueda ser utilizado en la elaboración del queso Poro con leche pasteurizada

Implementation tells us more beyond pooled estimates: Secondary analysis of a multicountry mhealth trial to reduce blood pressure

Background: The uptake of an intervention aimed at improving health-related lifestyles may be influenced by the participant’s stage of readiness to change behaviors. Objective: We conducted secondary analysis of the Grupo de Investigación en Salud Móvil en América Latina (GISMAL) trial according to levels of uptake of intervention (dose-response) to explore outcomes by country, in order to verify the consistency of the trial’s pooled results, and by each participant’s stage of readiness to change a given lifestyle at baseline. The rationale for this secondary analysis is motivated by the original design of the GISMAL study that was independently powered for the primary outcome—blood pressure—for each country. Methods: We conducted a secondary analysis of a mobile health (mHealth) multicountry trial conducted in Argentina, Guatemala, and Peru. The intervention consisted of monthly motivational phone calls by a trained nutritionist and weekly tailored text messages (short message service), over a 12-month period, aimed to enact change on 4 health-related behaviors: salt added to foods when cooking, consumption of high-fat and high-sugar foods, consumption of fruits or vegetables, and practice of physical activity. Results were stratified by country and by participants’ stage of readiness to change (precontemplation or contemplation; preparation or action; or maintenance) at baseline. Exposure (intervention uptake) was the level of intervention (<50%, 50%-74%, and ≥75%) received by the participant in terms of phone calls. Linear regressions were performed to model the outcomes of interest, presented as standardized mean values of the following: blood pressure, body weight, body mass index, waist circumference, physical activity, and the 4 health-related behaviors. Results: For each outcome of interest, considering the intervention uptake, the magnitude and direction of the intervention effect differed by country and by participants’ stage of readiness to change at baseline. Among those in the high intervention uptake category, reductions in systolic blood pressure were only achieved in Peru, whereas fruit and vegetable consumption also showed reductions among those who were at the maintenance stage at baseline in Argentina and Guatemala. Conclusions: Designing interventions oriented toward improving health-related lifestyle behaviors may benefit from recognizing baseline readiness to change and issues in implementation uptake.Fil: Carrillo-Larco, Rodrigo M.. Universidad Peruana Cayetano Heredia; Perú. Imperial College London; Reino UnidoFil: Jiwani, Safia S.. Universidad Peruana Cayetano Heredia; PerúFil: Diez Canseco, Francisco. Universidad Peruana Cayetano Heredia; PerúFil: Kanter, Rebecca. Institute of Nutrition of Central America and Panama; Guatemala. Universidad de Chile; ChileFil: Beratarrechea, Andrea Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Institute for Clinical Effectiveness and Health Policy; ArgentinaFil: Irazola, Vilma. Institute for Clinical Effectiveness and Health Policy; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ramirez Zea, Manuel. Institute of Nutrition of Central America and Panama; GuatemalaFil: Rubinstein, Adolfo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Epidemiología y Salud Pública. Instituto de Efectividad Clínica y Sanitaria. Centro de Investigaciones en Epidemiología y Salud Pública; ArgentinaFil: Martinez, Homero. Nutrition International; Canadá. Hospital Infantil de Mexico Federico Gomez; MéxicoFil: Miranda, J. Jaime. Cronicas Centro de Excelencia En Enfermedades Crónicas; Perú. Universidad Peruana Cayetano Heredia; PerúFil: Alasino, Adrían. Funprecal; ArgentinaFil: Budiel Moscoso, Berneth Nuris. Universidad Peruana Cayetano Heredia; PerúFil: Carrara, Carolina. Instituto Universitario del Hospital Italiano de Buenos Aires; ArgentinaFil: Espinoza Surichaqui, Jackelyn. Universidad Peruana Cayetano Heredia; PerúFil: Giardini, Gimena. Instituto Universitario del Hospital Italiano de Buenos Aires; ArgentinaFil: Guevara, Jesica. Institute of Nutrition of Central America And Panama Guatemala; GuatemalaFil: Morales Juárez, Analí. Institute of Nutrition of Central America And Panama Guatemala; GuatemalaFil: Lázaro Cuesta, Lorena. Funprecal; ArgentinaFil: Lewitan, Dalia. Institute For Clinical Effectiveness And Health Policy; ArgentinaFil: Palomares Estrada, Lita. Universidad Peruana Cayetano Heredia; PerúFil: Martínez Ramírez, Carla. Universidad Peruana Cayetano Heredia; PerúFil: de la Cruz, Gloria Robles. Universidad Peruana Cayetano Heredia; PerúFil: Salguero, Julissa. Institute Of Nutrition Of Central America And Panama Guatemala; GuatemalaFil: Saravia Drago, Juan Carlos. Universidad Peruana Cayetano Heredia; PerúFil: Urtasún, María. Institute For Clinical Effectiveness And Health Policy; ArgentinaFil: Zavala Loayza, José Alfredo. Universidad Peruana Cayetano Heredia; Per

The intracellular domain of β-dystroglycan mediates the nucleolar stress response by suppressing UBF transcriptional activity

β-dystroglycan (β-DG) is a key component of multiprotein complexes in the plasma membrane and nuclear envelope. In addition, β-DG undergoes two successive proteolytic cleavages that result in the liberation of its intracellular domain (ICD) into the cytosol and nucleus. However, stimuli-inducing ICD cleavage and the physiological relevance of this proteolytic fragment are largely unknown. In this study we show for the first time that β-DG ICD is targeted to the nucleolus where it interacts with the nuclear proteins B23 and UBF (central factor of Pol I-mediated rRNA gene transcription) and binds to rDNA promoter regions. Interestingly DG silencing results in reduced B23 and UBF levels and aberrant nucleolar morphology. Furthermore, β-DG ICD cleavage is induced by different nucleolar stressors, including oxidative stress, acidosis, and UV irradiation, which implies its participation in the response to nucleolar stress. Consistent with this idea, overexpression of β-DG elicited mislocalization and decreased levels of UBF and suppression of rRNA expression, which in turn provoked altered ribosome profiling and decreased cell growth. Collectively our data reveal that β-DG ICD acts as negative regulator of rDNA transcription by impeding the transcriptional activity of UBF, as a part of the protective mechanism activated in response to nucleolar stress

Strategies for continuous balancing in future power systems with high wind and solar shares

The use of wind power has grown strongly in recent years and is expected to continue to increase in the coming decades. Solar power is also expected to increase significantly. In a power system, a continuous balance is maintained between total production and demand. This balancing is currently mainly managed with conventional power plants, but with larger amounts of wind and solar power, other sources will also be needed. Interesting possibilities include continuous control of wind and solar power, battery storage, electric vehicles, hydrogen production, and other demand resources with flexibility potential. The aim of this article is to describe and compare the different challenges and future possibilities in six systems concerning how to keep a continuous balance in the future with significantly larger amounts of variable renewable power production. A realistic understanding of how these systems plan to handle continuous balancing is central to effectively develop a carbon-dioxide-free electricity system of the future. The systems included in the overview are the Nordic synchronous area, the island of Ireland, the Iberian Peninsula, Texas (ERCOT), the central European system, and Great Britain