Low THDi controller for current sensorless single phase rectifiers using a two-sample phase locked loop

Two-sample phase locked loop (2S PLL) with harmonic filtering capacity is used in a non-linear control (NLC) for a current sensorless Boost power factor corrector (PFC). The objective is to provide the sensorless NLC with a PLL based zero-crossing detector (ZCD) reference to obtain a sinusoidal line current, even under harmonically distorted grid voltages, which requires a proper grid synchronization, especially in the case of weak electrical grids. The resulting line current using the proposed 2S PLL and a ZCD are compared in simulation and experimentally.This work has been supported by the Spanish Ministry of Science and Innovation under Projects TEC2014-52316-R ECOTREND - Estimation and Optimal Control for Energy Conversion with Digital Devices and RTI2018-095138-BC31 PEGIA - Power Electronics for the Grid and Industry Application

Implementation oriented two-sample phase locked loop for single-phase PFCs

A low-resource-consuming digital implementation of the Two-Sample (2S) Phase Locked Loop (PLL) for application in low cost single-phase Power Factor Correction (PFC) converters is proposed. The design reduces the sampling rate of the grid voltage and replaces trigonometric functions by a digital oscillator and divisions by approximations, without reducing the 2S-PLL synchronization capability. The proposal is evaluated and validated with simulations and experimentally.This work has been supported by the Spanish Ministry of Science and Innovation under Project RTI2018-095138-BC31 PEGIA - Power Electronics for the Grid and Industry Applications

Neuropilin 1 Involvement in Choroidal and Retinal Neovascularisation

Purpose Inhibiting VEGF is the gold standard treatment for neovascular age-related macular degeneration (AMD). It is also effective in preventing retinal oedema and neovascularisation (NV) in diabetic retinopathy (DR) and retinal vein occlusions (RVO). Neuropilin 1 (Nrp1) is a co-receptor for VEGF and many other growth factors, and therefore a possible alternative drug target in intra ocular neovascular disease. Here we assessed choroidal and retinal NV in an inducible, endothelial specific knock out model for Nrp1. Methods Crossing Nrp1 floxed mice with Pdgfb-CreERT2 mice produced tamoxifen-inducible, endothelial specific Nrp1 knock out mice (Nrp1ΔEC) and Cre-negative, control littermates. Cre-recombinase activity was confirmed in the Ai3(RCL-EYFP) reporter strain. Animals were subjected to laser-induced CNV (532 nm) and spectral domain-optical coherence tomography (SD-OCT) was performed immediately after laser and at day 7. Fluorescein angiography (FA) evaluated leakage and postmortem lectin staining in flat mounted RPE/choroid complexes was also used to measure CNV. Furthermore, retinal neovascularisation in the oxygen induced retinopathy (OIR) model was assessed by immunohistochemistry in retinal flatmounts. Results In vivo FA, OCT and post-mortem lectin staining showed a statistically significant reduction in leakage (p<0.05), CNV volume (p<0.05) and CNV area (p<0.05) in the Nrp1ΔEC mice compared to their Cre-negative littermates. Also the OIR model showed reduced retinal NV in the mutant animals compared to wild types (p<0.001). Conclusion We have demonstrated reduced choroidal and retinal NV in animals that lack endothelial Nrp1, confirming a role of Nrp1 in those processes. Therefore, Nrp1 may be a promising drug target for neovascular diseases in the eye

Theoretical study of topological properties of ferromagnetic pyrite CoS₂

Since the discovery of the first topological material 15 years ago, the search for material realizations of novel topological phases has become the driving force of the field. While oftentimes we search for new materials, we forget that well established materials can also display very interesting topological properties. In this work, we revisit CoS2, a metallic ferromagnetic pyrite that has been extensively studied in the literature due to its magnetic properties. We study the topological features of its electronic band structure and identify Weyl nodes and nodal lines, as well as a symmetry-protected fourfold fermion close to the Fermi level. Looking at different surface cleavage planes, we observe both spin polarized Fermi arcs in the majority channel and drumhead states. These findings suggest that CoS2 is a promising platform to study topological phenomena, as well as a good candidate for spintronic applications

The subchalcogenides Ir₂In₈Q (Q = S, Se, Te): Dirac semimetal candidates with re-entrant structural modulation

Subchalcogenides are uncommon compounds where the metal atoms are in unusually low formal oxidation states. They bridge the gap between intermetallics and semiconductors, and can have unexpected structures and properties because of the exotic nature of their chemical bonding, as they contain both metal-metal and metal-main group (e.g. halide, chalcogenide) interactions. Finding new members of this class of materials presents synthetic challenges, as attempts to make them often result in phase separation into binary compounds. We overcome this difficulty by utilizing indium as a metal flux to synthesize large (mm scale) single crystals of novel subchalcogenide materials. Herein, we report two new compounds Ir2In8Q (Q = Se, Te) and compare their structural and electrical properties to the previously reported Ir2In8S analogue. Ir2In8Se and Ir2In8Te crystallize in the P42/mnm space group and are isostructural to Ir2In8S but also have commensurately modulated (with q-vectors q = 1/6a* + 1/6b* and q= 1/10a* + 1/10b* for Ir2In8Se and Ir2In8Te, respectively) low temperature phase transitions, where the chalcogenide anions in the channels experience a distortion in the form of In-Q bond alternation along the ab plane. Both compounds display re-entrant structural behavior, where the supercells appear on cooling but revert to the original subcell below 100 K, suggesting competing structural and electronic interactions dictate the overall structure. Notably, these materials are topological semimetal candidates with symmetry-protected Dirac crossings near the Fermi level, and exhibit high electron mobilities (~1500 cm2 V-1 s-1 at 1.8 K) and moderate carrier concentrations (~1020 cm-3) from charge transport measurements. This work highlights metal flux as a powerful synthetic route to high quality single crystals of novel intermetallic subchalcogenides

La importancia de los trabajos de campo en la confección del modelo del terreno para aplicaciones en ecología

The main aim of this paper is to highlight the extraordinary importance of field surveying for carrying out certain ecological models in which habitats of vegetal communities are conditioned by land elevation. An illustrated case study in the wetlands of Doñana National Park shows the key role of Field Inspections, particularly since morphology (altitude attribute) is one of the first factors that condition the superficial expansion of the main vegetal perennial communities within the wetland system.Se pretende demostrar la extraordinaria incidencia que tienen los trabajos de campo en la confecci&oacute;n de determinados modelos ecol&oacute;gicos, en los que el relieve del terreno condiciona el h&aacute;bitat de sus principales comunidades vegetales. Se ilustra esta hip&oacute;tesis con un ejemplo extra&iacute;do de la marisma del Parque Nacional de Do&ntilde;ana, donde su morfolog&iacute;a es uno de los factores principales que configura la fisonom&iacute;a del paisaje vegetal, al condicionar la expansi&oacute;n de las principales agrupaciones vegetales perennes del sistema marisme&ntilde;o