Instituto de Investigacións Tecnolóxicas

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A Single Picture Explains Diversity of Hyperthermia Response of Magnetic Nanoparticles
(American Chemical Society, 2015) Conde Leborán, Iván; Baldomir Fernández, Daniel; Martínez Boubeta, Carlos; Chubykalo-Fesenko, Oksana; Puerto Morales, María del; Salas, Gorka; Cabrera, David; Camarero, Julio; Teran, Francisco J.; Serantes Abalo, David; Universidade de Santiago de Compostela. Departamento de Física Aplicada; Universidade de Santiago de Compostela. Instituto de Investigacións Tecnolóxicas
Progress in the design of nanoscale magnets for localized hyperthermia cancer therapy has been largely driven by trial-and-error approaches, for instance, by changing of the stoichiometry composition, size, and shape of the magnetic entities. So far, widely different and often conflicting heat dissipation results have been reported, particularly as a function of the nanoparticle concentration. Thus, achieving hyperthermia-efficient magnetic ferrofluids remains an outstanding challenge. Here we demonstrate that diverging heat-dissipation patterns found in the literature can be actually described by a single picture accounting for both the intrinsic magnetic features of the particles (anisotropy, magnetization) and experimental conditions (concentration, magnetic field). Importantly, this general magnetic-hyperthermia scenario also predicts a novel non-monotonic concentration dependence with optimum heating features, which we experimentally confirmed in iron oxide nanoparticle ferrofluids by fine-tuning the particle size. Overall, our approach implies a magnetic hyperthermia trilemma that may constitute a simple strategy for development of magnetic nanomaterials for optimal hyperthermia efficiency.
Nanoparticle size threshold for magnetic agglomeration and associated hyperthermia performance
(MDPI, 2021) Serantes Abalo, David; Baldomir Fernández, Daniel; Universidade de Santiago de Compostela. Departamento de Física Aplicada; Universidade de Santiago de Compostela. Instituto de Investigacións Tecnolóxicas
The likelihood of magnetic nanoparticles to agglomerate is usually estimated through the ratio between magnetic dipole-dipole and thermal energies, thus neglecting the fact that, depending on the magnitude of the magnetic anisotropy constant (K), the particle moment may fluctuate internally and thus undermine the agglomeration process. Based on the comparison between the involved timescales, we study in this work how the threshold size for magnetic agglomeration (daggl) varies depending on the K value. Our results suggest that small variations in K-due to, e.g., shape contribution, might shift daggl by a few nm. A comparison with the usual superparamagnetism estimation is provided, as well as with the energy competition approach. In addition, based on the key role of the anisotropy in the hyperthermia performance, we also analyse the associated heating capability, as non-agglomerated particles would be of high interest for the application
Calidad ambiental de suelos y aguas de la Mina Fé: situación inicial y alternativas de recuperación
(Universia, 2020) Arán Ferreiro, Diego; Verde Vilanova, José Ramón; Antelo Martínez, Juan; Macías Vázquez, Felipe; Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola; Universidade de Santiago de Compostela. Instituto de Investigacións Tecnolóxicas
La actividad minera contribuye a diferentes impactos ambientales. Tras el cierre es esencial una evaluación holística del estado de los principales componentes del ecosistema y de sus riesgos medioambientales, a modo de establecer y gestionar un programa de rehabilitación sostenible y especifico a la situación ambiental existente. El objetivo de este trabajo fue evaluar la calidad química de los suelos y aguas de escorrentía de la mina de uranio, mina Fé (Saelices el Chico, España), con el fin de obtener un diagnóstico de la problemática ambiental existente y de las potenciales intervenciones de recuperación a aplicar. Los suelos localizados dentro del área minera y los suelos naturales de la zona adyacente fueron muestreados, analizados fisicoquímicamente y clasificados según la World Reference Base. Además, fueron recogidas muestras de aguas de escorrentía de las escombreras, para evaluación química y termodinámica, así como, en el período seco, eflorescencias de sales de la superficie de los materiales para análisis química y mineralógica. Los suelos naturales (clasificados como Leptosoles líticos, háplicos y esqueletales, Cambisoles lépticos y háplicos, Acrisoles plínticos y Fluvisoles háplicos y gleicos) presentan baja fertilidad (evaluada por la concentración de nutrientes y materia orgánica) y una fuerte tendencia erosiva lo que, junto con las condiciones climáticas de la zona, conllevan a un escaso desarrollo de la cobertura vegetal. Asimismo, estos suelos sólo se mantienen, de forma muy incipiente, en las áreas donde existe una cobertura vegetal permanente. La mayoría de los suelos de mina están desarrollados sobre diferentes mezclas de material de partida y residuos de mina ricos en sulfuros, clasificándose como Tecnosoles espólicos, sulfúricos o sálicos, dependiendo de sus propiedades y/o condiciones específicas. Estas mezclas de materiales disminuyen el efecto negativo de los materiales de escombrera, ya que las concentraciones totales de los elementos potencialmente tóxicos son similares (excepto para el Pb) a las determinadas en los suelos naturales. Sin embargo, estos suelos tienen elevado riesgo ambiental debido a la generación de drenajes hiperácidos (pH ≈ 2,8), hiperoxidantes (Eh ≈ 759 mV), hiperconductoras (CE ≈ 12,8 dS m-1) con altos contenidos en elementos potencialmente tóxicos (ej. Al, Fe y Mn) y sulfatos (22,9-33,9 g L-1). En el periodo seco, la ascensión por capilaridad de este drenaje contribuye a la formación de sales evaporíticas sobre los materiales las cuales fueron identificadas, principalmente, como sulfatos de Al y Mg (epsomita y halotricita). Estas fases sólidas son únicamente sumideros temporales de sulfato y metales, pues se redisuelven con las lluvias liberando nuevamente los elementos al medio. Además, la baja fertilidad y capacidad de cambio, acidez, pedregosidad y salinidad de los suelos de mina limitan la colonización natural y el desarrollo vegetativo. Teniendo en cuenta el riego ambiental y las características/condicionantes de los suelos de mina, el proceso de recuperación de la mina Fé debe enfocarse, principalmente, en la minimización de la oxidación de los sulfuros y mejora de la fertilidad para, consecuentemente, promover el establecimiento de una cobertura vegetal biodiversa y los procesos de edafogénesis y biogeoquímicos
Increasing the optical response of TiO2 and extending it into the visible region through surface activation with highly stable Cu5 clusters
(Royal Society of Chemistry, 2019) Lara Castells, María Pilar de; Hauser, Andreas W.; Ramallo López, José Martín; Buceta Fernández, David; Giovanetti, Lisandro J.; López Quintela, Manuel Arturo; Requejo, Félix G.; Universidade de Santiago de Compostela. Departamento de Química Física; Universidade de Santiago de Compostela. Instituto de Investigacións Tecnolóxicas
The decoration of semiconductors with subnanometer-sized clusters of metal atoms can have a strong impact on the optical properties of the support. The changes induced differ greatly from effects known for their well-studied, metallic counterparts in the nanometer range. In this work, we study the deposition of Cu5 clusters on a TiO2 surface and investigate their influence on the photon-absorption properties of TiO2 nanoparticles via the computational modeling of a decorated rutile TiO2 (110) surface. Our findings are further supported by selected experiments using diffuse reflectance and X-ray absorption spectroscopy. The Cu5 cluster donates an electron to TiO2, leading to the formation of a small polaron Ti3+ 3d1 state and depopulation of Cu(3d) orbitals, successfully explaining the absorption spectroscopy measurements at the K-edge of copper. A monolayer of highly stable and well fixated Cu5 clusters is formed, which not only enhances the overall absorption, but also extends the absorption profile into the visible region of the solar spectrum via direct photo-induced electron transfer and formation of a charge-separated state
Metabolic modeling for predicting VFA production from protein‐rich substrates by mixed‐culture fermentation
(Wiley, 2020-01) Regueira López, Alberte; Lema Rodicio, Juan Manuel; Carballa Arcos, Marta; Mauricio Iglesias, Miguel; Universidade de Santiago de Compostela. Departamento de Enxeñaría Química; Universidade de Santiago de Compostela. Instituto de Investigacións Tecnolóxicas; Área de Enxeñaría e Arquitectura
Proteinaceous organic wastes are suitable substrates to produce high added‐value products in anaerobic mixed‐culture fermentations. In these processes, the stoichiometry of the biotransformation depends highly on operational conditions such as pH or feeding characteristics and there are still no tools that allow the process to be directed toward those products of interest. Indeed, the lack of product selectivity strongly limits the potential industrial development of these bioprocesses. In this work, we developed a mathematical metabolic model for the production of volatile fatty acids from protein‐rich wastes. In particular, the effect of pH on the product yields is analyzed and, for the first time, the observed changes are mechanistically explained. The model reproduces experimental results at both neutral and acidic pH and it is also capable of predicting the tendencies in product yields observed with a pH drop. It also offers mechanistic insights into the interaction among the different amino acids (AAs) of a particular protein and how an AA might yield different products depending on the relative abundance of other AAs. Particular emphasis is placed on the utility of this mathematical model as a process design tool and different examples are given on how to use the model for this purpose
Modelling the production of VFA from proteins by mixed culture fermentations
(2019-06) Regueira López, Alberte; Bevilacqua, Riccardo; Lema Rodicio, Juan Manuel; Mauricio Iglesias, Miguel; Carballa Arcos, Marta; Universidade de Santiago de Compostela. Departamento de Enxeñaría Química; Universidade de Santiago de Compostela. Instituto de Investigacións Tecnolóxicas; Área de Enxeñaría e Arquitectura
Mixed-culture fermentations (MCF) are recognised as a valid process to yield added-value products from organic wastes in the form of volatile fatty acids (VFA). The use of mixed cultures is attractive due to their economical and operational advantages (e.g. no sterilisation is needed). However, they also pose a fundamental challenge: they are complex and their regulation mechanisms remain still unclear. One of the main limitations of the process is its low product selectivity: the productivity of the different VFA is highly dependant on operational conditions (e.g. pH, retention time or feeding characteristics). In consequence, developing bioprocesses based on this technology remains a challenging task. In this context, we aim at establishing a model-based methodology for developing novel bioprocess using MCF. The emphasis is placed on two aspects: to reach a high productivity and a high selectivity on the desired VFA(s). The improvement of selectivity is carried out by means of a metabolic energy-based model while the productivity is maximised using a general kinetic-based model
Ferromagnetic and insulating behavior of LaCoO3 films grown on a (001) SrTiO3 substrate: A simple ionic picture explained ab initio
(American Physical Society, 2017-10-06) Otero Fumega, Adolfo; Pardo Castro, Víctor; Universidade de Santiago de Compostela. Departamento de Física Aplicada; Universidade de Santiago de Compostela. Instituto de Investigacións Tecnolóxicas
This paper shows that the oxygen vacancies observed experimentally in thin films of LaCoO3 subject to tensile strain are thermodynamically stable according to ab initio calculations. By using DFT calculations, we show that oxygen vacancies on the order of 6% forming chains perpendicular to the (001) direction are more stable than the stoichiometric solution. These lead to magnetic Co2+ ions surrounding the vacancies that couple ferromagnetically. The remaining Co3+ cations in an octahedral environment are nonmagnetic. The gap leading to a ferromagnetic insulating phase occurs naturally and we provide a simple ionic picture to explain the resulting electronic structure
Targeted conversion of protein and glucose waste streams to valatile fatty acids by metabolic models
(2019-10) Regueira López, Alberte; Bevilacqua, Riccardo; Lema Rodicio, Juan Manuel; Carballa Arcos, Marta; Mauricio Iglesias, Miguel; Universidade de Santiago de Compostela. Departamento de Enxeñaría Química; Universidade de Santiago de Compostela. Instituto de Investigacións Tecnolóxicas; Área de Enxeñaría e Arquitectura
Mixed-culture fermentations are recognised as suitable processes to valorise organic wastes and convert them into added-value products. One of the main issues of these processes is that the stoichiometry of the fermentations is highly dependent on operational conditions such as the pH or the concentrations of the different substrates. In this work we developed a mathematical model for the production of volatile fatty acids from wastes featuring high concentrations of carbohydrates and proteins. The model reproduces experimental results, predicting the tendencies of the product spectrum when varying pH values and at different proportions of carbohydrates and proteins in the feeding. This model can be the core of a tool for the computer-aided design of mixed-culture fermentations
Modelling VFA production kinetics from protein-rich industrial wastes
(2019-07) Regueira López, Alberte; Bevilacqua, Riccardo; Lema Rodicio, Juan Manuel; Mauricio Iglesias, Miguel; Carballa Arcos, Marta; Universidade de Santiago de Compostela. Departamento de Enxeñaría Química; Universidade de Santiago de Compostela. Instituto de Investigacións Tecnolóxicas; Área de Enxeñaría e Arquitectura
Automatic decision support system based on SAR data for oil spill detection
(Elsevier, 2014-07-31) Mera Pérez, David; Cotos Yáñez, José Manuel; Varela Pet, José; Rodríguez, Pablo G.; Caro, Andrés; Universidade de Santiago de Compostela. Centro de Investigación en Tecnoloxías da Información; Universidade de Santiago de Compostela. Instituto de Investigacións Tecnolóxicas
Global trade is mainly supported by maritime transport, which generates important pollution problems. Thus, effective surveillance and intervention means are necessary to ensure proper response to environmental emergencies. Synthetic Aperture Radar (SAR) has been established as a useful tool for detecting hydrocarbon spillages on the oceans surface. Several Decision Support Systems have been based on this technology. This paper presents an automatic oil spill detection system based on SAR data which was developed on the basis of confirmed spillages and it was adapted to an important international shipping route off the Galician coast (northwest Iberian Peninsula). The system was supported by an adaptive segmentation process based on wind data as well as a shape oriented characterization algorithm. Moreover, two classifiers were developed and compared. Thus, image testing revealed up to 95.1% candidate labeling accuracy. Shared-memory parallel programming techniques were used to develop algorithms in order to improve above a 25% of the system processing time
Roman military settlements in the Northwest of the Iberian Peninsula. The contribution of historical and modern aerial photography, satellite imagery and airbone LiDAR [Póster]
(2015-09-04) Costa García, José Manuel; Fonte, João; Menéndez Blanco, Andrés; González Álvarez, David; Gago Mariño, Manuel; Blanco Rotea, Rebeca
The use of aerial photography for the detection and study of Roman military settlements in the Iberian Peninsula is not new. However, the impetus given to the discipline in recent decades also requires a significant renovation of its methodological approaches. In this paper, we present a low-cost methodology combining historical and modern aerial photography, satellite imagery, airborne LiDAR, GIS and conventional archaeological field survey techniques. These tools not only provide a new and qualitatively differential approach to archaeology, but also allow the study of the sites from a diachronic perspective. Our aim in this paper is to test the potential and limitations of these techniques in the specific study of several early Roman camps, a type of settlement characterized by the perishable nature of its structures and the shortage of material findings associated to them. Since it is also important to consider the different ownership and land use structures, we have selected a group of sites located in the territories of Galicia, Asturias, León and northern Portugal as case study.
Two glimpses to the religious landscapes of 6th Century Galicia (NW Spain)
(2014-11-25) Sánchez Pardo, José Carlos; Blanco Rotea, Rebeca; García Quintela, Marco Virgilio
En este poster se sintetizan los resultados de dos proyectos que tienen en común el estudio de los paisajes cristianos altomedievales de Galicia. Por un lado se ofrece una visión global de la territorialidad de Galicia en el siglo VI a partir del documento conocido como "Parroquial Suevo", redactado en torno al 570 d.C. Por otro lado se aborda el análisis interdisciplinar del territorio de la parroquia de Santa Mariña de Augas Santas (Allariz) y se rastrean los orígenes de la leyenda fuertemente enraizada en este lugar. Ambos proyectos coinciden en mostrar que en el siglo VI importantes cambios ocurrieron en el paisaje del Noroeste peninsular, en los cuales tuvo también un importante papel el desarrollo y organización del cristianismo y las estructuras eclesiásticas.
Quick 3D record: a low-cost method of documentation and analysis of scattered architectures in the EMCHAHE project
(2014-08-29) Mañana Borrazás, Patricia; Blanco Rotea, Rebeca; Sánchez Pardo, José Carlos
This work makes part of the Marie Curie CIG EMCHAHE project: Early Medieval Churches: History, Archaeology and Heritage (2013-2017), lead by José Carlos Sánchez-Pardo at the University of Santiago de Compostela (Spain). The research area of this project is the archaeology and history of the early medieval rural churches and their value for cultural management in Galicia (Northwest Spain). EMCHAHE is a project with several methodological challenges that we must face with limited resources. One of these challenges is the territorial scale, which involves the analysis of a large number of sites scattered through three rural areas of Galicia. This dispersion increases the problems and the cost of the access and the study of each church. Another one is the difficulty of identifying and analysing evidence of early medieval phases in the churches due to the frequent existence of several reforms and reconstructions. Therefore, it is necessary to apply a church documentation method as agile in field as accurate enough, which allows recording the graphic and geometric information necessary for a detailed study (stratigraphic analysis of the walls, identification of architectural elements, etc.) with the lowest cost. The poster will summarize the workflow and results of this quick and low-cost record of scattered churches proposal.
PDF3D del Modelo Fotogramétrico de tapa de estola de sarcófago de la Capela dos Mártores (Valga, Pontevedra)
(2014-08-28) Blanco Rotea, Rebeca; Mañana Borrazás, Patricia; Sánchez Pardo, José Carlos
Dos PDF3D interactivos realizados a partir del modelo fotogramétrico de una tapa de estola de un sarcófago conservada en el exterior de la capilla de San Mamede dos Mártores (Valga). El modelo se ha hecho en el contexto del desarrollo del proyecto Marie Curie EMCHAHE "Early Medieval Churches: History, Archaeology and Heritage" de la USC liderado por José Carlos Sánchez-Pardo.

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