Quantitative Decoding of Interactions in Tunable Nanomagnet Arrays Using First Order Reversal Curves

To develop a full understanding of interactions in nanomagnet arrays is a persistent challenge, critically impacting their technological acceptance. This paper reports the experimental, numerical and analytical investigation of interactions in arrays of Co nanoellipses using the first-order reversal curve (FORC) technique. A mean-field analysis has revealed the physical mechanisms giving rise to all of the observed features: a shift of the non-interacting FORC-ridge at the low-H$_c$ end off the local coercivity H$_c$ axis; a stretch of the FORC-ridge at the high-H$_c$ end without shifting it off the H$_c$ axis; and a formation of a tilted edge connected to the ridge at the low-H$_c$ end. Changing from flat to Gaussian coercivity distribution produces a negative feature, bends the ridge, and broadens the edge. Finally, nearest neighbor interactions segment the FORC-ridge. These results demonstrate that the FORC approach provides a comprehensive framework to qualitatively and quantitatively decode interactions in nanomagnet arrays.Comment: 19 pages, 4 figures. 9 page supplemental material including 3 figure

On the relationship between pump chirp and single-photon chirp in spontaneous parametric downconversion

We study the chronocyclic character, i.e. the joint temporal and spectral properties, of the single-photon constituents of photon pairs generated by spontaneous parametric down conversion. In particular we study how single photon properties, including purity and single-photon chirp, depend on photon pair properties, including the type of signal-idler spectral and correlations and the level of pump chirp.Comment: 13 pages, 6 figure

Improvement of mechanical and biological properties of Polycaprolactone loaded with Hydroxyapatite and Halloysite Nanotubes

[EN] Hydroxyapatite (HA) and Halloysite nanotubes (HNTs) percentages have been optimized in Polycaprolactone (PCL) polymeric matrices to improve mechanical, thermal and biological properties of the composites, thus, to be applied in bone tissue engineering or as fixation plates. Addition of HA guarantees a proper compatibility with human bone due to its osteoconductive and osteoinductive properties, facilitating bone regeneration in tissue engineering applications. Addition of HNTs ensures the presence of tubular structures for subsequent drug loading in their lumen, of molecules such as curcumin, acting as controlled drug delivery systems. The addition of 20% of HA and different amounts of HNTs leads to a substantial improvement in mechanical properties with values of flexural strength up to 40% over raw PCL, with an increase in degradation temperature. DMA analyses showed stability in mechanical and thermal properties, having as a result a potential composite to be used as tissue engineering scaffold or resorbable fixation plate.Torres-Roca, E.; Fombuena, V.; Vallés Lluch, A.; Ellingham, T. (2017). Improvement of mechanical and biological properties of Polycaprolactone loaded with Hydroxyapatite and Halloysite Nanotubes. Materials Science and Engineering C. 75:418-424. doi:10.1016/j.msec.2017.02.087S4184247

Diálogo entre povos indígenas: a experiência de dois encontros mediados pelo vídeo

The article analyses the role of video in intercultural communication from the interaction that is established among indigenous groups which met each other by vídeo images, afterwards, they ended up meeting personally, "in real life". The description of two of these encouters, between Waiãpi (AP) and Zo'e (PA), and between Gavião/Parkatêjê (PA) and Krahô (TO), provides context to the documentaries produced by the project Vídeo nas Aldeias/CTI about these experiences.O artigo propõe-se analisar o papel do vídeo na comunicação intercultural, a partir da interação que se estabelece entre grupos indígenas que se conheceram inicialmente por intermédio de imagens de vídeo e acabam se encontrando "na vida real". A descrição dos dois encontros - respectivamente entre os Waiãpi (AP) e os Zo´e (PA) e entre os Gavião/Parkatêjê (PA) e os Krakô (TO) - contextualiza os documentárias produzidos pelo projeto Vídeo nas Aldeias/CTI sobre estas experiências

Influence of the feedstock characteristics on the microstructure and properties of Al2O3 TiO2 plasma-sprayed coatings

[EN] Atmospheric plasma spraying (APS) is an interesting technique to obtain nanostructured coatings due to its versatility, simplicity and relatively low cost. However, nanometric powders cannot be fed into the plume using conventional feeding systems, due to their low mass and poor flowability, and must be adequately reconstituted into sprayable micrometric agglomerates. In this work, Al2O3–13 wt.%TiO2 nanostructured and submicron-nanostructured powders were deposited using APS. The feedstocks were obtained by spray drying from two starting suspensions, prepared by mixing two commercial nanosuspensions of Al2O3 and TiO2, or by adding nanosized TiO2 and submicron-sized Al2O3 powders to water. The spray-dried granules were heat-treated to reduce their porosity and the resultant powders were fully characterized. Optimization of the deposition conditions enabled the reconstituted powders to be successfully deposited, yielding coatings that were well bonded to the substrate. The coating microstructure, characterized by SEM, was formed by semi-molten feedstock agglomerates surrounded by fully molten particles that act as a binder. Moreover, microhardness, adhesion, and tribological behavior were determined, and the impact of the granule characteristics on these properties was studied. It was found that changing the feedstock characteristics allowed controlling the coating quality and properties.This work has been supported by the Spanish Ministry of Science and Innovation (project MAT2009-14144-C03).Vicent, M.; Bannier, E.; Benavente Martínez, R.; Salvador Moya, MD.; Molina, T.; Moreno, R.; Sánchez, E. (2013). Influence of the feedstock characteristics on the microstructure and properties of Al2O3 TiO2 plasma-sprayed coatings. Surface and Coatings Technology. 220:74-79. https://doi.org/10.1016/j.surfcoat.2012.09.042S747922

Atomistic insights into the degradation of halide perovskites: a reactive force field molecular dynamics study

Halide perovskites make efficient solar cells due to their exceptional optoelectronic properties, but suffer from several stability issues. The characterization of the degradation processes is challenging because of the limitations in the spatio-temporal resolution in experiments and the absence of efficient computational methods to study the reactive processes. Here, we present the first effort in developing reactive force fields for large scale molecular dynamics simulations of the phase instability and the defect-induced degradation reactions in inorganic CsPbI$_{3}$. We find that the phase transitions are driven by a combination of the anharmonicity of the perovskite lattice with the thermal entropy. At relatively low temperatures, the Cs cations tend to move away from the preferential positions with good contacts with the surrounding metal halide framework, potentially causing its conversion to a non-perovskite phase. Our simulations of defective structures reveal that, although both iodine vacancies and interstitials are very mobile in the perovskite lattice, the vacancies have a detrimental effect on the stability, initiating the decomposition reactions of perovskites to PbI$_{2}$. Our work puts ReaxFF forward as an effective computational framework to study reactive processes in halide perovskites.Comment: 11 pages, 6 figure

Vortex liquid entanglement in twinned YBa_2Cu_3O_7 /Y_2BaCuO_5 composite superconductors

The angular dependence of the in-plane resistivity ρ(T,H, θ) of melt textured YBa_2Cu_3O_7/Y_2BaCuO_5 composites has been measured in a large range of magnetic fields and temperatures and from them, the intrinsic anisotropy of the superconducting state has been verified following the anisotropic Ginzburg-Landau approach. The influence of correlated defects like twin boundaries and quenched disorder generated by Y_2BaCuO_5 precipitates on the pinning behavior of these composites in the liquid vortex state is analyzed, and the corresponding phase diagram is determined and compared to that of twinned single crystals. We show that the irreversibility line displays an upwards shift due to twin boundary pinning enabling to define a ''quenched'' Bose glass transition. A new region in the vortex liquid state is identified where twin boundary pinning defines a partially entangled liquid vortex state characterized by a short-range c-axis vortex coherence. The transition to the entangled liquid phase is experimentally determined. The relevance of this depinning line and its unique position with respect to twinned single crystals is discussed. [S0163- 1829(99)01741-5]

Uncrewed aircraft system spherical photography for the vertical characterization of canopy structural traits

The plant area index (PAI) is a structural trait that succinctly parametrizes the foliage distribution of a canopy and is usually estimated using indirect optical techniques such as digital hemispherical photography. Critically, on-the-ground photographic measurements forgo the vertical variation of canopy structure which regulates the local light environment. Hence new approaches are sought for vertical sampling of traits. We present an uncrewed aircraft system (UAS) spherical photographic method to obtain structural traits throughout the depth of tree canopies. Our method explained 89% of the variation in PAI when compared with ground-based hemispherical photography. When comparing UAS vertical trait profiles with airborne laser scanning data, we found highest agreement in an open birch (Betula pendula/pubescens) canopy. Minor disagreement was found in dense spruce (Picea abies) stands, especially in the lower canopy. Our new method enables easy estimation of the vertical dimension of canopy structural traits in previously inaccessible spaces. The method is affordable and safe and therefore readily usable by plant scientists.Peer reviewe

Turbidity patterns in the Albufera lake, Spain, and their relation to irrigation cycles

[EN] The Albufera Natural Park (Valencia, Spain) is one of the most representative coastal wetlands in the Mediterranean basin. It holds several protection designations at national and international level, such as Spanish Natural Park, Special Protection Areas (SPAs) for birds, Sites of Community Importance (SCIs) and Ramsar Site. Both the park and its main lake, Albufera¿s lake, face several environmental problems. One of them is reduced transparency and lake clogging. The lake is highly dependent on the rice cycle and on irrigation returns, mainly from the Acequia Real. In this study, we analyse the monthly transparency and turbidity patterns during year 2018, and we relate them to irrigation cycles. We used Sentinel 2A satellite images from the European Space Agency, which have an atmospheric correction. Remote sensing results were compared with in situ data from the monitoring program of the Environment General Subdivision of the regional government. This monitoring program samples five points on a monthly basis, and analyses Secchi disk depth, suspended solids and chlorophyll a. Our results show the temporal and spatial pattern of turbidity in the Albufera lake which offers relevant information for water resources management.María-Teresa Sebastiá-Frasquet was beneficiary of the CAS18/00107 post-doctoral research grant, supported by the Spanish Ministry of Education Culture and Sports during her stay at the Universidad Autónoma de Baja California (Mexico), image processing was partially developed during the staySebastiá-Frasquet, M.; Aguilar-Maldonado, JA.; Santamaría-Del-Ángel, E.; Altur Grau, VJ. (2019). Turbidity patterns in the Albufera lake, Spain, and their relation to irrigation cycles. WIT Transactions on Ecology and the Environment (Online). 239:173-180. https://doi.org/10.2495/WS190151S17318023

Adaptation of urban uses of environmental characteristics: A case study of La Safor, Valencia, Spain

[EN] In the 1990s a methodology was developed to apply the concept of land aptitude to urban plans. This methodology was based on the concepts of capacity and vulnerability in the face of different urban uses (e.g. residential use, industrial use and strategic facilities). The methodology was implemented thanks to geographical information systems (GIS) mapping of available cartography. In recent years, the available cartography has increased in quantity and in spatial resolution. Also, urban planning and environmental legislation have evolved. In this study, we propose a methodological update to incorporate all these changes. The updated methodology is applied to La Safor (Valencia, Spain), which is a region composed of 31 municipalities. La Safor is a model case study because of its characteristics that makes it representative of both coastal and inner areas. Our results point out the need to incorporate legal constraints to the methodology. Including climate adaptation is also essential for strategic urbanism and to accomplish environmental requirements. The methodology presented can be defined as an integrated assessment tool necessary for sustainable development and minimizing environmental risks.Altur Grau, VJ.; Aguilar-Maldonado, JA.; Sebastiá-Frasquet, M.; Miralles García, JL. (2019). Adaptation of urban uses of environmental characteristics: A case study of La Safor, Valencia, Spain. WIT Transactions on Ecology and the Environment (Online). 238:187-198. https://doi.org/10.2495/SC190171S18719823