Open problems in the magnetic behavior of iron-oxide nanoparticles

Los sistemas nanoestructurados presentan una serie de propiedades particulares que han dado lugar a una nueva fenomenología física. A pesar del extensivo estudio que se ha realizado de estos materiales, todavía existen cuestiones abiertas relativas a sus propiedades magnéticas. En este trabajo se ha abordado el momento magnético en nanopartículas antiferromagnéticas, efectos de superficie en la imanación de saturación de nanopartículas ferrimagnéticas y el efecto de las interacciones dipolares en la relajación magnética de ferrofluidos

Ink transport modelling in Dip-Pen Nanolithography and Polymer Pen Lithography

Dip-pen nanolithography (DPN) and Polymer pen lithography (PPL) are powerful lithography techniques being able to pattern a wide range of inks. Transport and surface spreading depend on the ink physicochemical properties, defining its diffusive and fluid character. Structure assembly on surface arises from a balance between the entanglement of the ink itself and the interaction with the substrate. According to the transport characteristics, different models have been proposed. In this article we review the common types of inks employed for patterning, the particular physicochemical characteristics that make them flow following different dynamics as well as the corresponding transport mechanisms and models that describe them

Dilute Gd hydroxycarbonate particles for localized spin qubit integration

Molecular spins are considered as the quantum hardware to build hybrid quantum processors in which coupling to superconducting devices would provide the means to implement the necessary coherent manipulations. As an alternative to large magnetically-dilute crystals or concentrated nano-scale deposits of paramagnetic molecules that have been studied so far, the use of pre-formed sub-micronic spherical particles of a doped Gd@Y hydroxycarbonate is evaluated here. Particles with an adjustable number of spin carriers are prepared through the control of both particle size and doping. Bulk magnetic properties and continuous wave and time-domain-EPR spectroscopy show that the Gd spins in these particles are potential qubits with robust quantum coherence. Monolayers of densely-packed particles are then formed interfacially and transferred successfully to the surface of Nb superconducting resonators. Alternatively, these particles are disposed at controlled localizations as isolated groups of a few particles through Dip-Pen Nanolithography using colloidal organic dispersions as ink. Altogether, this study offers new material and methodologies relevant to the development of viable hybrid quantum processors

Integración de drones en unidades de caballería para la realización de reconocimientos de itinerario y objetivo o puntual.

Las actuales Secciones Ligero-Acorazadas de Caballería son las principales unidades de la fuerza encargadas de realizar los reconocimientos en misiones internacionales en las que España participa. El proyecto ha surgido de la necesidad de incorporar nuevos avances tecnológicos a los reconocimientos de Caballería para dotarles de unas capacidades que aumenten la seguridad de la fuerza de reconocimiento, así como la velocidad y calidad de los mismos. El presente trabajo analiza la integración de drones en misiones de reconocimiento de itinerario y de objetivo o puntual, realizados por las Secciones Ligero-Acorazadas de Caballería y evalúa la viabilidad de dicha integración, tomando como universo de estudio los reconocimientos de itinerario, puente y zona boscosa. Durante el desarrollo del proyecto se ha determinado el tipo de dron idóneo para estas misiones, los medios y procedimientos necesarios para su integración, así como sus limitaciones. Como conclusión se ha demostrado la viabilidad de la integración de drones en las Secciones Ligero-Acorazadas para la realización de tareas de reconocimiento, así como para analizar terrenos inaccesibles para el personal y medios actuales, proporcionando información exacta y precisa en tiempo real, sin involucrar ni exponer medios o personal.<br /

Evaluation of triphenylene-based MOF ultrathin films for lithium batteries

Metal–organic frameworks (MOFs) are attractive candidates to meet the requirement of next-generation batteries, as functional materials with a high surface area, well-defined metal centers, and organic linkers through coordination bonds. Due to their great tunability, MOFs have been investigated as electrodes or electrolytes in lithium batteries and more recently as protective layers in anode-less batteries. Here, we synthesize a Ni3(HHTP)2 MOF directly at the air–liquid interface of a Langmuir trough and grow the electrode on a conductive substrate by the transference process. The characterization during Langmuir film formation shows that the addition of crystallization time during the compression process enhances the formation of 2D crystalline domains, as observed by in situ grazing-incidence X-ray diffraction. Next, the transferred Ni3(HHTP)2 ultrathin films were studied as working electrodes in Li batteries in a half-cell configuration and compared with bare copper. The results show that the Ni3(HHTP)2 film protects the Cu collector from oxidation, and the negative charge accumulates in the organic ligand during the lithiation process while NiII oxidizes to NiIII, unlike other triphenylene-based MOFs with CuII or CoII metal nodes. The galvanostatic plating–stripping cycles of the batteries show that the inclusion of the crystallization time improves the coulombic efficiency, especially significantly in the first cycles when the SEI is formed. This work shows the Langmuir technique as a useful tool to test MOF based materials for batteries with the advantages of using a low amount of raw materials and without the need to introduce additives (binder and electron conductor) in the electrodes. The electrochemical study of this type of electrode allows a first screening to synthesize electrodes based on MOFs and can be a tool for the preparation of protective coatings under optimized conditions

Ten lessons on the resilience of the EU common fisheries policy towards climate change and fuel efficiency - A call for adaptive, flexible and well-informed fisheries management

To effectively future-proof the management of the European Union fishing fleets we have explored a suite of case studies encompassing the northeast and tropical Atlantic, the Mediterranean, Baltic and Black Seas. This study shows that European Union (EU) fisheries are likely resilient to climate-driven short-term stresses, but may be negatively impacted by long-term trends in climate change. However, fisheries' long-term stock resilience can be improved (and therefore be more resilient to increasing changes in climate) by adopting robust and adaptive fisheries management, provided such measures are based on sound scientific advice which includes uncertainty. Such management requires regular updates of biological reference points. Such updates will delineate safe biological limits for exploitation, providing both high long-term yields with reduced risk of stock collapse when affected by short-term stresses, and enhanced compliance with advice to avoid higher than intended fishing mortality. However, high resilience of the exploited ecosystem does not necessarily lead to the resilience of the economy of EU fisheries from suffering shocks associated with reduced yields, neither to a reduced carbon footprint if fuel use increases from lower stock abundances. Fuel consumption is impacted by stock development, but also by changes in vessel and gear technologies, as well as fishing techniques. In this respect, energy-efficient fishing technologies already exist within the EU, though implementing them would require improving the uptake of innovations and demonstrating to stakeholders the potential for both reduced fuel costs and increased catch rates. A transition towards reducing fuel consumption and costs would need to be supported by the setup of EU regulatory instruments. Overall, to effectively manage EU fisheries within a changing climate, flexible, adaptive, well-informed and well-enforced management is needed, with incentives provided for innovations and ocean literacy to cope with the changing conditions, while also reducing the dependency of the capture fishing industry on fossil fuels. To support such management, we provide 10 lessons to characterize 'win-win' fishing strategies for the European Union, which develop leverages in which fishing effort deployed corresponds to Maximum Sustainable Yield targets and Common Fisheries Policy minimal effects objectives. In these strategies, higher catch is obtained in the long run, less fuel is spent to attain the catch, and the fisheries have a higher resistance and resilience to shock and long-term factors to face climate-induced stresses

Open problems in the magnetic behavior of iron-oxide nanoparticles

Los sistemas nanoestructurados presentan una serie de propiedades particulares que han dado lugar a una nueva fenomenología física. A pesar del extensivo estudio que se ha realizado de estos materiales, todavía existen cuestiones abiertas relativas a sus propiedades magnéticas. En esta Tesis se ha abordado el momento magnético en nanopartículas antiferromagnéticas, efectos de superficie en la imanación de saturación de nanopartículas ferrimagnéticas y el efecto de las interacciones dipolares en la relajación magnética de ferrofluidos

Dilute Gd hydroxycarbonate particles for localized spin qubit integration

Molecular spins are considered as the quantum hardware to build hybrid quantum processors in which coupling to superconducting devices would provide the means to implement the necessary coherent manipulations. As an alternative to large magnetically-dilute crystals or concentrated nano-scale deposits of paramagnetic molecules that have been studied so far, the use of pre-formed sub-micronic spherical particles of a doped Gd@Y hydroxycarbonate is evaluated here. Particles with an adjustable number of spin carriers are prepared through the control of both particle size and doping. Bulk magnetic properties and continuous wave and time-domain-EPR spectroscopy show that the Gd spins in these particles are potential qubits with robust quantum coherence. Monolayers of densely-packed particles are then formed interfacially and transferred successfully to the surface of Nb superconducting resonators. Alternatively, these particles are disposed at controlled localizations as isolated groups of a few particles through Dip-Pen Nanolithography using colloidal organic dispersions as ink. Altogether, this study offers new material and methodologies relevant to the development of viable hybrid quantum processors.This research was supported by the European Union Horizon 2020 research and innovation program through FET-OPEN grant FATMOLS-No 862893, the Spanish MCIN/AEI/10.13039/501100011033 and ERDF “A way of making Europe” (projects PID2019-105881RB-I00 and PID2020-1183294RB-I00), the Aragón government (PLATON E31_20R and E31_23R, doctoral grant to IT), and the CSIC Research Platform PTI-001 QUTEP.Peer reviewe

A Porphyrin Spin Qubit and Its 2D Framework Nanosheets

Molecular spin qubits have been shown to reach sufficiently long quantum coherence times to envision their use as hardware in quantum processors. These will however require their implementation in hybrid solid‐state devices for which the controlled localization and homogeneous orientation of the molecular qubits will be necessary. An alternative to isolated molecules that can ensure these key aspects is 2D framework in which the qubit would act as node. In this work, it is demonstrated that the isolated metalloporphyrin [Cu(H4TCPP)] molecule is a potential spin qubit, and maintains similar quantum coherence as node in a 2D [{CuTCPP}Zn2(H2O)2] metal–organic framework. Mono‐ and multilayer deposits of nanosheets of a similar 2D framework are then successfully formed following a modular method based on Langmuir–Schaefer conditions. The orientation of the {CuTCPP} qubit nodes in these nanosheets is homogeneous parallel to the substrate. These nanosheets are also formed with a control over the qubit concentration, i.e., by dilution with the unmetallated porphyrin. Eventually, 2D nanosheets are formed in situ directly on a substrate, through a simple protocol devised to reproduce the Langmuir–Schaefer conditions locally. Altogether these studies show that 2D spin qubit frameworks are ideal components to develop a hybrid quantum computing architecture.The authors acknowledge funding from the Spanish MINECO through projects MAT2014-53961-R (O.R., E.N.), MAT2015-70868-ERC (O.R., A.U.), MAT2016-78257-R (I.G., M.A.A.), MAT2017-86826-R (O.R., E.N., A.U.), and CTQ2015-64486-R (P.J.A.), as well as from the Aragón government (DGA, consolidated group PLATON E31_17R). M.A.A. acknowledges the support of Spanish Ministerio de Educación for a FPU grant. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231.Peer reviewe