Spin-phonon induced magnetic order in Kagome ice

We study the effects of lattice deformations on the Kagome spin ice, with Ising spins coupled by nearest neighbor exchange and long range dipolar interactions, in the presence of in-plane magnetic fields. We describe the lattice energy according to the Einstein model, where each site distortion is treated independently. Upon integration of lattice degrees of freedom, effective quadratic spin interactions arise. Classical MonteCarlo simulations are performed on the resulting model, retaining up to third neighbor interactions, under different directions of the magnetic field. We find that, as the effect of the deformation is increased, a rich plateau structure appears in the magnetization curves.Comment: 7 pages, 8 figure

From chiral spin liquids to skyrmion fluids and crystals, and their interplay with itinerant electrons

We present an in-depth study of the competition between skyrmions and a chiral spin liquid in a model on the kagome lattice that was recently proposed by some of the authors [H. D. Rosales, et al. Phys. Rev. Lett. 130, 106703 (2023)]. We present an analytical overview of the low-energy states using the Luttinger-Tisza approximation. Then we add thermal fluctuations thanks to large-scale Monte-Carlo simulations, and explore the entire parameter space with a magnetic field $B$, in-plane $D^{xy}$ and out-of-plane $D^z$ Dzyaloshinskii-Moriya interactions, using the ferromagnetic strength as unit of energy. While skyrmions and the chiral spin liquid live in different regions of parameter space, we show how to bring them together, stabilizing a skyrmion fluid in between; a region where the density of well-defined skyrmions can be tuned from quasi-zero (gas) to saturated (liquid) before ordering of the skyrmions (solid). In particular, we investigate the two-dimensional melting of the skyrmion solid. Our analysis also brings to light a long-range ordered phase with Z$_3$ symmetry. To conclude, when conduction electrons are coupled to the local spins, different chiral magnetic textures stabilized in this model (skyrmion solid, liquid and gas \& chiral spin liquid) induce anomalous Quantum Hall effect in the magnetically disordered skyrmion liquid for specific band-filling fractions. Landau levels persist even in the skyrmion-liquid regime in absence of broken translational symmetry and gradually disappear as the skyrmion density decreases to form a gas.Comment: 18 pages, 16 figure

Optimización de propiedades mecánicas y térmicas de un aglomerado sintético por el Método de Taguchi

In this work, the Taguchi Experimental Design model was applied for the optimization of the mechanical and thermal properties of an agglomerated composite material and to obtain the most appropriate parameters for its elaboration. The importance of the development of synthetic agglomerates is in the use of agricultural waste to give it a useful use when supplying high demand materials. Rice husk, clay, sand and aloe gel were used as raw materials. With the variation of the values ​​of the control factors: percentage of rice husk (R), temperature (T) and time of heat treatment (t), the different experimental combinations were performed. For the optimization of the mechanical and thermal properties according to the Taguchi methodology, the mechanical and thermal tests were selected: the modulus of elasticity, the energy absorbed in the impact, the modulus of maximum breakage and the initial decomposition temperature for each combination chipboard experimental. For the processing of this data, the software for the automatic design and analysis of Taguchi experiments, Qualitek-4, was used under the characteristic of higher-better quality. The optimal parameters obtained for each level of control were R = 15%, T = 120 C and t = 3 h. These results were validated with the performance of a confirmatory experiment, where properties similar to those of wood species were obtained for this agglomerate. The development of this prototype of alternative material will be useful as a substitute for wood and will contribute to the reduction of the environmental impact generated by waste products.En este trabajo se aplicó el modelo de Diseño Experimental de Taguchi para la optimización de las propiedades mecánicas y térmicas de un material compuesto aglomerado y obtener los parámetros más adecuados para su elaboración. La importancia del desarrollo de los aglomerados sintéticos está en el uso de desechos agrícolas para darle un empleo útil al suplir materiales de gran demanda. Se utilizaron la cáscara de arroz, arcilla, arena y gel de aloe como materias primas. Con la variación de los valores de los factores de control: porcentaje de cáscara de arroz (R), temperatura (T) y tiempo de tratamiento térmico (t), se realizaron las diferentes combinaciones experimentales. Para la optimización de las propiedades mecánicas y térmicas según la metodología de Taguchi, se seleccionaron de las pruebas mecánicas y térmicas: el módulo de elasticidad, la energía absorbida en el impacto, el módulo de rotura máximo y la temperatura inicial de descomposición para cada combinación experimental de aglomerado. Para el procesamiento de estos datos, se utilizó el software para el diseño automático y análisis de experimentos de Taguchi, Qualitek-4, bajo la característica de calidad mayor–mejor. Los parámetros óptimos obtenidos para cada nivel de control, fueron R = 15%, T = 120 C y t = 3 h. Estos resultados fueron validados con la realización de un experimento confirmatorio, donde se obtuvieron, para este aglomerado, propiedades similares a las de unas especies de madera. El desarrollo de este prototipo de material alternativo será útil como sustituyente de la madera y contribuirá a la reducción del impacto ambiental generado por los productos de desecho

Optimización de propiedades mecánicas y térmicas de un aglomerado sintético por el Método de Taguchi

In this work, the experimental design of Taguchi model was applied in order to obtain the most appropriate parameters to elaborate an agglomerate material which presents a good mechanical and thermal behavior. The raw materials used were rice husk, common clay, sand and aloe gel. The importance of the development of the synthetic agglomerates is in the use of agricultural wastes to give them an useful employment when replacing materials of great demand. The experimental combinations were done varying the control factors values: rice husk percentage (R), temperature (T) and thermal treatment time(t). Via to the optimization properties according Taguchi’s Methodology, the elasticity modulus, the absorbed energy in the impact, break maximum module and initial decomposition temperature to each experimental combination were selected. The Qualitek-4 software was used below the biggest the better quality characteristic. The optimum parameters obtained to each control level were: R = 15%, T = 120oC and t = 3 h. These results were confirmed with a new experiment, where similar properties to the wood species were obtained. The developing of this will be useful as substitute of the wood and could improve the environment impact due residual materials.PACS: 88.30.mj, 81.70.Bt, 82.35.PqMSC: 91B82En este trabajo se aplicó el modelo de Diseño Experimental de Taguchi para la optimización de las propiedades mecánicas y térmicas de un material compuesto aglomerado y obtener los parámetros más adecuados para su elaboración. La importancia del desarrollo de los aglomerados sintéticos está en el uso de desechos agrícolas para darle un empleo útil al suplir materiales de gran demanda. Se utilizaron la cáscara de arroz, arcilla, arena y gel de aloe como materias primas. Con la variación de los valores de los factores de control: porcentaje de cáscara de arroz (R), temperatura (T) y tiempo de tratamiento térmico (t), se realizaron las diferentes combinaciones experimentales. Para la optimización de las propiedades mecánicas y térmicas según la metodología de Taguchi, se seleccionaron de las pruebas mecánicas y térmicas: el módulo de elasticidad, la energía absorbida en el impacto, el módulo de rotura máximo y la temperatura inicial de descomposición para cada combinación experimental de aglomerado. Para el procesamiento de estos datos, se utilizó el software para el diseño automático y análisis de experimentos de Taguchi, Qualitek-4, bajo la característica de calidad mayor–mejor. Los parámetros óptimos obtenidos para cada nivel de control, fueron R = 15%, T = 120 C y t = 3 h. Estos resultados fueron validados con la realización de un experimento confirmatorio, donde se obtuvieron, para este aglomerado, propiedades similares a las de unas especies de madera. El desarrollo de este prototipo de material alternativo será útil como sustituyente de la madera y contribuirá a la reducción del impacto ambiental generado por los productos de desecho.PACS: 88.30.mj, 81.70.Bt, 82.35.PqMSC: 91B8

Estrategias de manejo y monitoreo del recurso hídrico en Ahuisculco

En el proyecto de estrategias de manejo y monitoreo del recurso hídrico en Ahuisculco se realizó una propuesta de metodología viable de tratamiento de aguas residuales domésticas de humedales, según las necesidades de la comunidad y las condiciones de Ahuisculco. Además de una propuesta de estandarización de métodos analíticos para la gestión de la calidad del agua del pueblo, una propuesta de tecnología para el aprovechamiento de las aguas pluviales para abastecer un huerto en la primaria de Ahuisculco y formación a estudiantes y familias sobre la concientización de la importancia del agua y la importancia nutritiva de los cultivos urbanos. Este proyecto tiene sus antecedentes en el verano del 2020, en el cual se consideró la posibilidad de implementar una planta de tratamiento de aguas para las comunidades de Ahuisculco, Las Navajas y Cuxpala, así como una metodología de monitoreo y control de la calidad del agua mediante un manual. Al ser este un proyecto integral que unifica varias líneas de trabajo se divide por apartado cada uno de estos subproyectos con la finalidad de representar cada uno con claridad, así como los objetivos, alcances y resultados de cada unoITESO, A.C

Intermediate magnetization state and competing orders in Dy2Ti2O7 and Ho2Ti2O7

We thank R. Moessner, C. Castelnovo and M. Gingras for helpful discussions, and the financial support of ANPCYT through PICT 2013-2004 and PICT 2014-2618 and CONICET (Argentina), the EPSRC and the Royal Society (UK).Among the frustrated magnetic materials, spin-ice stands out as a particularly interesting system. Residual entropy, freezing and glassiness, Kasteleyn transitions and fractionalization of excitations in three dimensions all stem from a simple classical Hamiltonian. But is the usual spin-ice Hamiltonian a correct description of the experimental systems? Here we address this issue by measuring magnetic susceptibility in the two most studied spin-ice compounds, Dy2Ti2O7 and Ho2Ti2O7, using a vector magnet. Using these results, and guided by a theoretical analysis of possible distortions to the pyrochlore lattice, we construct an effective Hamiltonian and explore it using Monte Carlo simulations. We show how this Hamiltonian reproduces the experimental results, including the formation of a phase of intermediate polarization, and gives important information about the possible ground state of real spin-ice systems. Our work suggests an unusual situation in which distortions might contribute to the preservation rather than relief of the effects of frustration.Publisher PDFPeer reviewe

Valorisation of black mulberry and grape seeds: Chemical characterization and bioactive potential

Grape (Vitis vinifera L. var. Albariño) and mulberry (Morus nigra L.) seeds pomace were characterized in terms of tocopherols, organic acids, phenolic compounds and bioactive properties. Higher contents of tocopherols (28 ± 1 mg/100 g fw) were obtained in mulberry, whilst grape seeds were richer in organic acids (79 ± 4 mg/100 g fw). The phenolic analysis of hydroethanolic extracts characterised grape seeds by catechin oligomers (36.0 ± 0.3 mg/g) and mulberry seeds by ellagic acid derivatives (3.14 ± 0.02 mg/g). Both exhibited high antimicrobial activity against multiresistant Staphylococcus aureus MIC = 5 mg/mL) and no cytotoxicity against carcinogenic and non-tumour primary liver (PLP) cells. Mulberry seeds revealed the strongest inhibition (p lt 0.05) against thiobarbituric reactive substances (IC50 = 23 ± 2 µg/mL) and oxidative haemolysis (IC50 at 60 min = 46.0 ± 0.8 µg/mL). Both seed by-products could be exploited for the developing of antioxidant-rich ingredients with health benefits for industrial application.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020); C. L. Roriz PhD’s grant (SFRH/BD/117995/2016), L. Barros to FCT, P.I., through the institutional scientific employment program-contract for their contract and the individual scientific employment program-contract for S.A. Heleno’s contract. To Eramus + grant (P BRAGAC01) and the Complutense University of Madrid, Spain for the preodoctoral grant [CT17/17-CT18/17] of E. Gómez-Mejía. In addition, to the Complutense University of Madrid, Spain for the preodoctoral grant [CT17/17-CT18/17] of E. Gómez-Mejía. In addition, to the companies Ponto Agricola Lda. (Portugal) and Terras Gaudas (Spain) for providing the sample by-products. The authors are grateful to FEDER-Interreg España-Portugal programme for financial support through the project 0377_Iberphenol_6_E.info:eu-repo/semantics/publishedVersio