Voltage dip generator for testing wind turbines connected to electrical networks

This paper describes a new voltage dip generator that allows the shape of the time profile of the voltage generated to be configured. The use of this device as a tool to test the fault ride-through capability of wind turbines connected to the electricity grid can provide some remarkable benefits: First, this system offers the possibility of adapting the main features of the time–voltage profile generated (dip depth, dip duration, the ramp slope during the recovery process after clearing fault, etc.) to the specific requirements set forth by the grid operation codes, in accordance with different network electrical systems standards. Second, another remarkable ability of this system is to provide sinusoidal voltage and current wave forms during the overall testing process without the presence of harmonic components. This is made possible by the absence of electronic converters. Finally, the paper includes results and a discussion on the experimental data obtained with the use of a reduced size laboratory prototype that was constructed to validate the operating features of this new device

Intracellular trafficking and cellular uptake mechanism of PHBV nanoparticles for targeted delivery in epithelial cell lines

Indexación: Web of Science; Scopus; Scielo.Background: Nanotechnology is a science that involves imaging, measurement, modeling and a manipulation of matter at the nanometric scale. One application of this technology is drug delivery systems based on nanoparticles obtained from natural or synthetic sources. An example of these systems is synthetized from poly(3-hydroxybutyrate-co-3-hydroxyvalerate), which is a biodegradable, biocompatible and a low production cost polymer. The aim of this work was to investigate the uptake mechanism of PHBV nanoparticles in two different epithelial cell lines (HeLa and SKOV-3). Results: As a first step, we characterized size, shape and surface charge of nanoparticles using dynamic light scattering and transmission electron microscopy. Intracellular incorporation was evaluated through flow cytometry and fluorescence microscopy using intracellular markers. We concluded that cellular uptake mechanism is carried out in a time, concentration and energy dependent way. Our results showed that nanoparticle uptake displays a cell-specific pattern, since we have observed different colocalization in two different cell lines. In HeLa (Cervical cancer cells) this process may occur via classical endocytosis pathway and some internalization via caveolin-dependent was also observed, whereas in SKOV-3 (Ovarian cancer cells) these patterns were not observed. Rearrangement of actin filaments showed differential nanoparticle internalization patterns for HeLa and SKOV-3. Additionally, final fate of nanoparticles was also determined, showing that in both cell lines, nanoparticles ended up in lysosomes but at different times, where they are finally degraded, thereby releasing their contents. Conclusions: Our results, provide novel insight about PHBV nanoparticles internalization suggesting that for develop a proper drug delivery system is critical understand the uptake mechanism.https://jnanobiotechnology.biomedcentral.com/articles/10.1186/s12951-016-0241-

Near-Infrared Polarimetric Adaptive Optics Observations of NGC 1068: A torus created by a hydromagnetic outflow wind

We present J' and K' imaging linear polarimetric adaptive optics observations of NGC 1068 using MMT-Pol on the 6.5-m MMT. These observations allow us to study the torus from a magnetohydrodynamical (MHD) framework. In a 0.5" (30 pc) aperture at K', we find that polarisation arising from the passage of radiation from the inner edge of the torus through magnetically aligned dust grains in the clumps is the dominant polarisation mechanism, with an intrinsic polarisation of 7.0%$\pm$2.2%. This result yields a torus magnetic field strength in the range of 4$-$82 mG through paramagnetic alignment, and 139$^{+11}_{-20}$ mG through the Chandrasekhar-Fermi method. The measured position angle (P.A.) of polarisation at K$'$ is found to be similar to the P.A. of the obscuring dusty component at few parsec scales using infrared interferometric techniques. We show that the constant component of the magnetic field is responsible for the alignment of the dust grains, and aligned with the torus axis onto the plane of the sky. Adopting this magnetic field configuration and the physical conditions of the clumps in the MHD outflow wind model, we estimate a mass outflow rate $\le$0.17 M$_{\odot}$ yr$^{-1}$ at 0.4 pc from the central engine for those clumps showing near-infrared dichroism. The models used were able to create the torus in a timescale of $\geq$10$^{5}$ yr with a rotational velocity of $\leq$1228 km s$^{-1}$ at 0.4 pc. We conclude that the evolution, morphology and kinematics of the torus in NGC 1068 can be explained within a MHD framework.Comment: 14 pages, 4 figures, Accepted by MNRA

Proper motions of the HH1 jet

We describe a new method for determining proper motions of extended objects, and a pipeline developed for the application of this method. We then apply this method to an analysis of four epochs of [S~II] HST images of the HH~1 jet (covering a period of $\sim 20$~yr). We determine the proper motions of the knots along the jet, and make a reconstruction of the past ejection velocity time-variability (assuming ballistic knot motions). This reconstruction shows an "acceleration" of the ejection velocities of the jet knots, with higher velocities at more recent times. This acceleration will result in an eventual merging of the knots in $\sim 450$~yr and at a distance of $\sim 80"$ from the outflow source, close to the present-day position of HH~1.Comment: 12 pages, 8 figure

Modelación del frijol en Latinoamérica: Estado del arte y base de datos para parametrización

Frijol común (Phaseolus vulgaris L.) es la leguminosa de grano para consumo humano de mayor producción en el mundo, y es nativo de las Américas, donde juega un papel importante en la dieta. Los ambientes donde se cultiva el frijol varían desde zonas tropicales hasta alta montaña, con diversos hábitos de crecimiento (arbustivo determinado, arbustivo indeterminado, y voluble), y en sistemas de producción desde los tradicionales hasta los altamente tecnificados. Los esfuerzos en modelaje, por tanto, deben empezar desde identificar el tipo de frijol y el sistema objetivo. El frijol es muy sensible al estrés abiótico, hecho que ha animado el modelaje de su posible respuesta bajo escenarios de cambio climático. Se llevó a cabo una revisión de literatura para identificar quince ejercicios de modelaje ejecutados en América Latina, abarcando estudios de crecimiento (tazas de producción de nudos y área foliar), fenología, y de rendimiento. Los modelos empleados en dichos estudios incluyen EcoCrop, CROPGRO-DRYBEAN (implementado en la plataforma DSSAT), y en un caso cada uno, Maxent y CLIMEX. Se describen cuatro estudios en detalle: en los dos países de mayor producción en el mundo (Brasil y México), y en Centroamérica como región altamente vulnerable al cambio climático. Estos estudios concuerdan que la productividad del frijol podría sufrir serios efectos negativos en el transcurso del Siglo XXI a raíz del cambio climático. Finalmente, se informa sobre un ejercicio reciente de recopilar datos históricos de ensayos de frijol en Latinoamérica para alimentar futuros esfuerzos de modelaje. Common bean (Phaseolus vulgaris L.) is the grain legume of greatest volume of production for direct human consumption, and is native to the Americas where it plays an important role in the diet of consumers. Bean is cultivated in environments from lowland tropical areas to high mountainous zones; with growth habits ranging from determinate bush, to indeterminate bush, to climbing types; and in production systems varying from traditional low input agriculture to highly technified systems. As such, efforts at modelling should focus on a specific plant type and production system. Bean is very sensitive to abiotic stress, a fact that has motivated modelling of its response in light of the dangers of climate change. A review of literature was carried out revealing fifteen studies in Latin America considering different aspects of plant growth (rates of node and leaf area production), phenology, and yield. Models employed include EcoCrop, CROPGRO (a module within the DSSAT cropping system model), and in one instance each, Maxent and CLIMEX. Three studies in particular are detailed: in the two countries of greatest production in the world (Brazil and Mexico), and one study in Central America as a region under direct threat of climate change. These three studies confirm that bean productivity will likely suffer severe negative effects in the course of the 21st century, as a result of climate change. A recent effort has compiled data from historical yield trials in Latin America as a resource for future modelling efforts.JRC.D.5-Food Securit