Topological defects and misfit strain in magnetic stripe domains of lateral multilayers with perpendicular magnetic anisotropy

Stripe domains are studied in perpendicular magnetic anisotropy films nanostructured with a periodic thickness modulation that induces the lateral modulation of both stripe periods and inplane magnetization. The resulting system is the 2D equivalent of a strained superlattice with properties controlled by interfacial misfit strain within the magnetic stripe structure and shape anisotropy. This allows us to observe, experimentally for the first time, the continuous structural transformation of a grain boundary in this 2D magnetic crystal in the whole angular range. The magnetization reversal process can be tailored through the effect of misfit strain due to the coupling between disclinations in the magnetic stripe pattern and domain walls in the in-plane magnetization configuration

Double percolation effects and fractal behavior in magnetic/superconducting hybrids

Perpendicular magnetic anisotropy ferromagnetic/ superconducting (FM/SC) bilayers with a labyrinth domain structure are used to study nucleation of superconductivity on a fractal network, tunable through magnetic history. As clusters of reversed domains appear in the FM layer, the SC film shows a percolative behavior that depends on two independent processes: the arrangement of initial reversed domains and the fractal geometry of expanding clusters. For a full labyrinth structure, the behavior of the upper critical field is typical of confined superconductivity on a fractal network.Comment: 15 pages, 5 figure

Controlled nucleation of topological defects in the stripe domain patterns of Lateral multilayers with Perpendicular Magnetic Anisotropy: competition between magnetostatic, exchange and misfit interactions

Magnetic lateral multilayers have been fabricated on weak perpendicular magnetic anisotropy amorphous Nd-Co films in order to perform a systematic study on the conditions for controlled nucleation of topological defects within their magnetic stripe domain pattern. A lateral thickness modulation of period $w$ is defined on the nanostructured samples that, in turn, induces a lateral modulation of both magnetic stripe domain periods $\lambda$ and average in-plane magnetization component $M_{inplane}$. Depending on lateral multilayer period and in-plane applied field, thin and thick regions switch independently during in-plane magnetization reversal and domain walls are created within the in-plane magnetization configuration coupled to variable angle grain boundaries and disclinations within the magnetic stripe domain patterns. This process is mainly driven by the competition between rotatable anisotropy (that couples the magnetic stripe pattern to in-plane magnetization) and in-plane shape anisotropy induced by the periodic thickness modulation. However, as the structural period $w$ becomes comparable to magnetic stripe period $\lambda$, the nucleation of topological defects at the interfaces between thin and thick regions is hindered by a size effect and stripe domains in the different thickness regions become strongly coupled.Comment: 10 pages, 7 figures, submitted to Physical Review

Life Cycle Assessment of Alkali Activated Cement compared to Ordinary Portland Cement

Approximately 8% of the global emissions of CO2 are originated by the cement industry, which consumes on average between 4 to 6 GJ per ton of cement. Ordinary Portland Cement (OPC) is the most used cement for construction purposes. Every year, around 4 billion tonnes (Gt) of OPC are manufactured. For each kg of OPC produced, 0.81 kg of CO2 is generated. Therefore, seeking cements with more environmentally friendly manufacturing process, economically viable, and socially relevant is necessary. One of the most promising materials are the Alkali-Activated Cements (AAC), where its components are an aluminosilicate precursor and alkaline activators. The precursor used in this study is Weathered Bottom Ash (WBA), a waste obtained from the Municipal Solid Waste Incineration (MSWI). On the other hand, the alkaline activators are sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). The name of the AAC developed is Sustainable-AAC (Sust-AAC). This project is focused on searching for new materials that could reduce the use of OPC as a building material. To be able to assess the associated environmental impacts, a comparison between AAC and OPC (CEM I) through a Life Cycle Assessment (LCA) following the standards ISO 14040:2006 and ISO 14044:2006 is performed. The LCA methodology allows identification and quantification of relevant inputs and outputs of the system, thus, evaluating the potential environmental impacts associated. The system boundary of this project is cradle-to-gate and the functional unit of the assessment is 1 ton of commercial cement. The OPC inventory is carried out through the values obtained in GaBi Software and the Sust-AAC inventory is made from the previous studies performed in the DIOPMA research group, on a laboratory scale. The results show that the OPC has higher impact on global warming, energy consumption, water consumption, and mineral extraction categories compared to Sust-AAC. In OPC manufacturing, the kiln stage is the most energy intensive stage (by the chemical reaction and by the fossil fuel requirement) and therefore, has the most significant environmental impact in terms of CO2 emissions and energy consumption. In contrast, the highest environmental impacts on the Sust-AAC are due to the production of Na2SiO3. The main reason for the energysaving is because Sust-AAC production does not need a kiln with high temperatures. In addition, the use of waste as raw material promotes a circular economy and, at the same time, reduces the extraction of natural resources. Then, the environmental performance in the Sust-AAC is promising compared to OPC. Sust-AAC is suitable to be used as lightweight material and as insulation material for thermal insulating applications. This application can contribute to realising operational energy savings and performance benefits

Geopolymers based on the valorization of Municipal Solid Waste Incineration residues

he proper management of Municipal Solid Waste (MSW) has become one of the main environmental commitments for developed countries due to the uncontrolled growth of waste caused by the consumption patterns of modern societies. Nowadays, municipal solid waste incineration (MSWI) is one of the most feasible solutions and it is estimated to increase in Europe where the accessibility of landfill is restricted. Bottom ash (BA) is the most significant by-product from MSWI as it accounts for 85-95 % of the solid product resulting from combustion, which is classified as a non-hazardous residue that can be revalorized as a secondary aggregate in road sub-base, bulk lightweight filler in construction. In this way, revalorization of weathered BA (WBA) for the production of geopolymers may be a good alternative to common reuse as secondary aggregate material; however, the chemical process to obtain these materials involves several challenges that could disturb the stability of the material, mainly from the environmental point of view. Accordingly, it is necessary that geopolymers are able to stabilize heavy metals contained in the WBA in order to be classified as non-hazardous materials. In this regard, the SiO2/Al2O3 ratio plays an important role for the encapsulation of heavy metals and other toxic elements. The aim of this research is to formulate geopolymers starting from the 0-2 mm particle size fraction of WBA, as a unique raw material used as aluminumsilicate precursor. Likewise, leaching tests of the geopolymers formulated were performed to assess their environmental impact. The findings show that it is possible to formulate geopolymers using 100 % WBA as precursor, although more investigations are needed to sustain that geopolymer obtained can be considered as non-hazardous materials

Tuning interfacial domain walls in GdCo/Gd/GdCo′ spring magnets

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).-- et al.Spring magnets based on GdCo multilayers have been prepared to study the nucleation and evolution of interfacial domain walls (iDWs) depending on layer composition and interlayer coupling. GdCo alloy compositions in each layer were chosen so that their net magnetization aligns either with the Gd (Gd35Co65) or Co(Gd11Co89) sublattices. This condition forces an antiparallel arrangement of the layers' net magnetization and leads to nucleation of iDWs above critical magnetic fields whose values are dictated by the interplay between Zeeman and exchange energies. By combining x-ray resonant magnetic scattering with Kerr magnetometry, we provide detailed insight into the nucleation and spatial profile of the iDWs. For strong coupling (GdCo/GdCo′ bilayer), iDWs are centered at the interface but with asymmetric width depending on each layer magnetization. When interlayer coupling is weakened by introducing a thin Gd interlayer, the exchange spring effect becomes restricted to a lower temperature and field range than observed in the bilayer structure. Due to the ferromagnetic alignment between the high magnetization Gd35Co65 layer and the Gd interlayer, the iDW shrinks and moves into the lower exchange Gd interlayer, causing a reduction of iDW energy.Work supported by Spanish Ministerio de Economía y Competitividad (MINECO) under grant FIS2013-45469 and Spanish Ministerio de Ciencia e Innovacion (MICINN) under grant FIS2008-06249. Work at Argonne was supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.Peer Reviewe

Caracterización de placas de yeso con residuos de espuma de poliuretano reforzadas con fibras de polipropileno

Gypsum plasterboard that incorporates various combinations of polyurethane foam waste and polypropylene fibers in its matrix is studied. The prefabricated material was characterized in a series of standardized tests: bulk density, maximum breaking load under flexion stress, total water absorption, surface hardness, thermal properties, and reaction to fire performance. Polypropylene fibers were added to the polyurethane gypsum composites to improve the mechanical behavior of the plasterboard under loading. The results indicate that increased quantities of polymer waste led to significant reductions in the weight/surface ratio, the mechanical strength and the surface hardness of the gypsum, as well as improving its thermal resistance. The polypropylene fibers showed good adhesion to the polymer and the gypsum matrix, which enhanced the mechanical performance and the absorption capacity of these compounds. The non-combustibility test demonstrated the potential of the new material for use in internal linings.Este artículo presenta un estudio experimental basado en la reutilización de residuos de poliuretano en una matriz de yeso para elaborar una placa de yeso laminado. Las placas fueron caracterizadas mediante los ensayos normalizados de densidad aparente, carga de rotura máxima a flexión, absorción total de agua, dureza superficial y reacción al fuego. Se han introducido fibras de polipropileno en la matriz con el objetivo de aumentar la resistencia mecánica del material. Los resultados muestran que el incremento de residuo polimérico en el material implica importantes reducciones de peso, resistencia mecánica y dureza superficial, a la par que se mejora su resistencia térmica consiguiéndose valores similares a los comerciales. Las fibras de polipropileno mostraron una buena adhesión con el polímero, mejorando el comportamiento mecánico y la capacidad de absorción. El ensayo de reacción al fuego confirmó que los residuos de poliuretano pueden ser empleados en la fabricación de placas de yeso laminado en cumplimiento con la normativa

Control of magnetic domain wall motion in Co microwires by tridimensional e-beam lithographied structures

Resumen del póster presentado al 6th Spanish Workshop in Nanolithography celebrado en Zaragoza (España) del 28 al 30 de octubre de 2014.Work supported by the Spanish MICINN FIS2008-06249 and CSIC JAE Predoc grants.Peer Reviewe

Duration of untreated psychosis: Impact of the definition of treatment onset on its predictive value over three years of treatment.

While reduction of DUP (Duration of Untreated Psychosis) is a key goal in early intervention strategies, the predictive value of DUP on outcome has been questioned. We planned this study in order to explore the impact of three different definition of "treatment initiation" on the predictive value of DUP on outcome in an early psychosis sample. 221 early psychosis patients aged 18-35 were followed-up prospectively over 36 months. DUP was measured using three definitions for treatment onset: Initiation of antipsychotic medication (DUP1); engagement in a specialized programme (DUP2) and combination of engagement in a specialized programme and adherence to medication (DUP3). 10% of patients never reached criteria for DUP3 and therefore were never adequately treated over the 36-month period of care. While DUP1 and DUP2 had a limited predictive value on outcome, DUP3, based on a more restrictive definition for treatment onset, was a better predictor of positive and negative symptoms, as well as functional outcome at 12, 24 and 36 months. Globally, DUP3 explained 2 to 5 times more of the variance than DUP1 and DUP2, with effect sizes falling in the medium range according to Cohen. The limited predictive value of DUP on outcome in previous studies may be linked to problems of definitions that do not take adherence to treatment into account. While they need replication, our results suggest effort to reduce DUP should continue and aim both at early detection and development of engagement strategies