In-situ electrochemical synthesis of inorganic compounds for materials conservation: Assessment of their effects on the porous structure

This study refers to the application of in-situ electrochemical synthesis as an alternative method to improve the properties of porous materials against harmful external agents that deteriorate them. It is oriented to an understanding of the effects of crystallisation on the pore structure of different compounds commonly used in the restoration and conservation of porous materials (historical ceramics, building walls, sculptures, or biomedical applications). It analyses the microstructural, chemical details, and stability of the neo-formed phases that modify the pore network. The electrochemical synthesis was carried out at ambient temperature (20 °C), over high porous sandstone for crystallising Ca carbonate, Mg carbonate, Ca phosphate, and Ca oxalate compounds. Based on the neo-formed minerals, a comparison was made depending on their specific properties defining how they affected the pore structure. The characterisation included polarised light optical microscopy, environmental and field-emission scanning electron microscopy, digital image analysis, cathodoluminescence (CL-ESEM),energy-dispersive X-ray spectroscopy, and X-ray microdiffraction. Aragonite, hydromagnesite, hydroxyapatite, and whewellite were identified as the majority phases depending on the treatment. Phase transformation, dehydration, and dissolution-re-precipitation processes suggested different degrees of stability, including aragonite/calcite (CaCO3 treatment) and hydromagnesite/magnesite (MgCO3 treatment) transformations and simultaneous crystallisation of brushite/hydroxyapatite ((Ca3(PO4)2 treatment). Electrocrystallisation induced changes in inter-granular porosity, the development of secondary porosity inherent to the minerals, and differences in pore cementation depending on its mineralogy. Among the treatments, Mg carbonate reduced porosity most effectively, followed in descending order by calcium carbonate and calcium phosphate, being the calcium oxalate the less effective.This work was funded by the following projects: TOP-HERITAGE- (Technologies in Heritage Sciences (S2018/NMT_4372, Community of Madrid); MULTIMAT CHALLENGE: Multifunctional Materials for Society Challenges (S2013/MIT-2862, Community of Madrid); Additive Manufacturing: from material to application, ADITIMAT-CM (S2018/ NMT-4411, Community of Madrid); MAT2016-80875-C3-3-R, (Spanish Ministry of Science, Innovation and Universities); Author J.F.‘s participation was supported by a Spanish Ministry of Sciences, Innovation and Universities Juan de la Cierva grant

TEM-STEM study of europium doped gadolinium oxide nanoparticles synthesized by spray pyrolysis

Proocedings of: Fourth Conference on the Characterization and Control of Interfaces for High Quality Advanced Materials. Kurashiki, Japan, 02-05 September 2012.Scanning-Transmission and Transmission Electron Microscopy techniques (STEM and TEM) have been applied to the characterization of nanostructured gadolinium oxides doped with europium synthesized by spray pyrolysis. The High Angle Annular Dark Field (HAADF) &- Scanning Transmission Electron Micros-copy (STEM) tools have been used to perform a tomographic study to identify morphological character-istics of nanostructured particles, and to differentiate them according to the heat treatments to which these have been subjected. With these techniques it has been possible to confirm the hollowness and por-ous nature of samples subjected to low temperature annealing (900 ºC). Moreover, the beginning of the densification and sintering processes in samples subjected to thermal treatment at higher temperature (1100 ºC) have been evaluated. Chemical analysis by electron energy loss spectroscopy (EELS) and X ray energy dispersive spectroscopy (EDS) carried out in STEM mode have allowed to confirm the high uni-formity and the expected chemical composition. The high resolution tools either allowed to confirm the presence of a cubic (Ia3 symmetry) and the monoclinic (c2/m symmetry) phases in the nanostructured particles.This work has been supported by the Advanced Structural Materials Program- ESTRUMAT (S2009/MAT-1585) and MAT2010-19837-C06-05. Thanks are extended to NanoPort (FEI)- Eindhoven, especially to Eng. L. Fernando Mendoza and to the Ministry of Science and Technology of Serbia (Project #142010).Publicad

Application of magnesium hydroxide nanocoatings on cellulose fibers with different refining degrees

Paper aging and protection are of crucial interest for improving the preservations of library collections and archives. Highly aging-resistant cellulose fiber sheets were obtained by treatment with magnesium hydroxide nanoparticles (Mg(OH)(2)). The procedure was tested on the sheets made of bleached (B) and refined unbleached (UB) pine cellulose fibers as well as their 50%/50% mixture (M). The mor and structural properties of the obtained sheets were studied by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) methods. Stress-strain, smoothness and pH measurements were employed to determine the changes in physical-chemical characteristics of the sheets after mixing two types of the fibers and subsequent treatment with Mg(OH)(2). It has been shown that the sheets made of the fiber mixture show a higher tensile index and smoothness. The modification with Mg(OH)(2) nanoparticles induces an increase in the pH of the sheets to slightly basic values (around pH 8), facilitates the inter-fiber bonding and additionally enhances the smoothness of the sheets. Finally, by exposing the sheets to thermo-hygrometric accelerated artificial ageing, it was found that the physical properties of the treated sheets were not significantly dependent on the environmental factors.This study was supported by the Geomaterials 2 Programme (S2013/MIT_2914),the Innovation and Education Ministry (ref. MAT2013-47460-C5-5-P) and the Autonomous Region Program of Madrid, MULTIMAT CHALLENGE (ref.S2013/MIT-2862

Synthesis and morpho-structural characterization of nanostructured magnesium hydroxide obtained by a hydrothermal method

Controlled magnesium hydroxide particles were successfully synthesized via a simple hydrothermal method. The influence of temperature and reaction time on the hydrothermal synthesis of Mg(OH)(2) was studied. The results provide new parameters to control the morphologies, particle sizes, agglomeration level and crystallographic structures of the brucite nanosized. The physic chemical properties of synthesized Mg(OH)(2) nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) combined with selected area electron diffraction (SAED), high resolution transmission electron microscopy (HR-TEM) and thermogravimetry/differential scanning calorimetry (TG/DSC). It has been shown that the prolongation of reaction time improves the crystalline degree of magnesium hydroxide particles. It was also possible to detect a relevant increase in the degree of crystallinity and a faster crystal growth with defined hexagonal morphologies in the samples obtained at higher temperature. Our results show that this simple hydrothermal route is highly interesting for the large scale production of these nanomaterials. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.This study has been supported by the Geomaterials Programme (S2009/MAT-1629) and the ESTRUMAT Programme (S2009/MAT-1585) and it has been carried out in the Department of Materials Science and Engineering and Chemical Engineering of the University Carlos III of Madrid, Spain. The authors are grateful to the National Center for Electron Microscopy (CNME) for its support with TEM

Atomic scale study of the dehydration/structural transformation in micro and nanostructured brucite (Mg(OH)(2)) particles: Influence of the hydrothermal synthesis conditions

Micro and nanostructured brucite (Mg(OH2)) particles synthesized by hydrothermal method from solutions with high content of hydrazine (0.14 M) and nitrate (0.24 g) were compared with samples obtained from low hydrazine content (0.0002 M) and nitrate (0.12 g). The samples were heated at 180 degrees C for 4 h, 6 h and 12 h. XRD, TEM-HRTEM, SAED and image analysis techniques were used for the morphological and structural characterization. The effect of electron beam irradiation on the brucite dehydration was observed in atomic resolution images at 300 kV. Hexagonal crystals show differences in crystallinity, strains and kinetic of reaction. High hydrazine/nitrate samples have slightly larger crystals with better crystallinity, showing a strong preferential orientation. Rietveld refinements show how unit cell parameters are bigger in samples obtained with higher hydrazine/nitrate content, confirming also the preferential orientation along the 0001 plane. Differences in the dehydration process show the rapid formation of a porous surface, the amorphised cortex or the presence of highly oriented strains in samples prepared from higher hydrazine/nitrate content. Conversely, crystals slightly smaller with randomly scattered defect surfaces showing the Mg(OH)(2)/MgO interphase in samples prepared with low hydrazine/nitrate content. Significant differences in the kinetic of reaction indicate how the dehydration process is faster in samples prepared with high hydrazine/nitrate content. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.This present research was funded by the Community of Madrid under the GEOMATERIALES II project (S2013/MIT-2914), by the Complutense University of Madrid’s Research Group: “The alteration and conservation of stone heritage” (921349), the Autonomous Region Program of Madrid, MULTIMAT-CHALLENGE (ref. S2013/MIT‐2862), the Innovation and Education Ministry ref. (MAT2013-47460-C5-5-P), the Mat201019837/C06-05 and the Ministry of Education, Science and Technological Development of Serbia (OI 1612046) projects. The authors are indebted to the Petrophysical Laboratory IGEO, affiliated with the Moncloa Campus of International Excellence CEI-09-009(UCM-UPM), the Heritage Laboratory Network in Science and Technology for Heritage Conservation (RedLabPat,) and the Materials Science Department (Carlos III University of Madrid)

Short-term exposure to benzalkonium chloride in bacteria from activated sludge alters the community diversity and the antibiotic resistance profile

The continuous introduction of cleaning products containing benzalkonium chloride (BAC) from household discharges can mold the microbial communities in wastewater treatment plants (WWTPs) in a way still poorly understood. In this study, we performed an in vitro exposure of activated sludge from a WWTP in Costa Rica to BAC, quantified the changes in intI1, sul2, and qacE/qacEΔ1 gene profiles, and determined alterations in the bacterial community composition. The analysis of the qPCR data revealed elevated charges of antibiotic resistance genes in the microbial community; after BAC’s exposure, a significant increase in the qacE/qacEΔ1 gene, which is related to ammonium quaternary resistance, was observed. The 16S rRNA gene sequences’ analysis showed pronounced variations in the structure of the bacterial communities, including reduction of the alpha diversity values and an increase of the relative abundance of Alphaproteobacteria, particularly of Rhodospseudomonas and Rhodobacter. We confirmed that the microbial communities presented high resilience to BAC at the mg/mL concentration, probably due to constant exposure to this pollutant. They also presented antibiotic resistance-related genes with similar mechanisms to tolerate this substance. These mechanisms should be explored more thoroughly, especially in the context of high use of disinfectant.Universidad de Costa Rica/[]/UCR/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigaciones en Productos Naturales (CIPRONA)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Centro de Investigación en Enfermedades Tropicales (CIET)UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí

Towards an identification of Learning Disabilities (LD) in the school: contributions of the American experience

RESUMEN: El presente artículo muestra el abordaje de una de las perspectivas a través de la cual los investigadores se han aproximado a la identificación y caracterización de las Dificultades de Aprendizaje (DA) como un trastorno neuropsicológico. No obstante, las diferencias,limitaciones e imprecisiones en la identificación de los estudiantes que las presentan han propiciado la generación de controversias, que influyen en los ámbitos sociopolítico, educativo, clínico y, por supuesto, investigativo. Contrarios a esta perspectiva, los sistemas de clasificación propuestos por la investigación han determinado que no permite diferenciar aquellos casos que realmente obedecen a la presencia de una incapacidad para aprender. Con este panorama, investigadores, profesionales del área clínica y agentes educativos se han visto enfrentados a la necesidad de establecer criterios de identificación precisos y que permitan el diseño de propuestas de intervención que respondan a sus necesidades. En él se recogen evidencias disponibles sobre los modelos de aproximación alas DA que subyacen en el contexto americano y que han alcanzado una mirada más integral y, en particular, a la determinación de los criterios para su caracterización y clasificación. En suma, se pretende ofrecer elementos para sustentar la importancia de lograr un modelo de operacionalización de las DA que apuesta por una identificación objetiva y centrada en un enfoque holístico, capaz de considerar los factores contextuales e individuales, dejando atrás las concepciones deficitarias que se enmarcan en una mirada absolutista, categórica y reduccionista.ABSTARCT: This article presents the approach to one of the perspectives commonly used by researchers to identify and characterize Learning Disabilities (LDs) as a neuropsychological disorder. However, the differences, limitations, and inaccuracies in identifying students with these conditions have raised debates that influence the social, political, educational, and clinical fields and, of course, have also affected research in this area. Contrary to such perspective, the classification systems suggested by research in this field have shown a difficulty in identifying the cases really connected to the presence of learning disabilities. In consequence, researchers, medical professionals, and educators feel the need to establish accurate identification criteria that lead to the design of intervention approaches that meet their needs. This reflects the available evidence on LD approaches that underlie the American context achieving a more comprehensive approach as well as clearer characterization and classification criteria. In short, the goal is to provide elements to support the importance of achieving a model of operationalization of LDs seeking an objective identification focused on a holistic approach and able to consider contextual and individual factors, leaving behind those deficient models that end in absolutist, categorical and reductionist conceptions

Passenger Centric Train Timetabling Problem with elastic demand

A wide taxonomy of the adopted design criterion in models for Train Timetabling Problem (TTP), considers two kinds of models: operations-centric models, which are focused on railway operations and assume the demand has been considered and modeled in the design stage of the railway network, and passenger-centric models, which tries to maximize customers satisfaction. The first models have been widely studied since historically, the train operating companies (TOC) had a monopoly in the railway market. Currently, and because of the European directive (EU Directive 91/440) which allows the competition between different TOC, the research interest in the second kind of models is increasing. This paper proposes a mathematical model for TTP which includes the elasticity of the demand against the characteristics of supply. To do that, the proposed model is based on the concept of strategy and by means of the use of radial-basis functions, the demand model allows to estimate the number of passengers in each strategy on the network, taking into account the existing correlation between strategies

Nuevos avances en el diseño de nanomateriales para la consolidación del patrimonio pétreo: evaluación de su efectividad en la dolomía de Laspra

Actas del Congreso Nacional "Estudio y Conservación del Patrimonio Cultural". Málaga, 16-19 de noviembre de 2015La piedra constituye el principal representante del patrimonio arquitectónico, estando la caliza yla dolomía entre los materiales más empleados a lo largo de la historia. El deterioro que sufren estosmateriales genera una importante pérdida de cohesión interna que hace necesaria la aplicación deproductos consolidantes. No obstante, en muchos de los casos estos productos son inadecuados yprovocan importantes procesos de deterioro, constituyendo uno de los principales factores de degradacióndel patrimonio. En este contexto, el desarrollo de los nanomateriales constituye una importante vía deactuación en la conservación del patrimonio cultural. La manipulación de los materiales a escalananométrica permite el menor trastorno posible a la obra original, mientras que de manera eficiente luchacontra los efectos del tiempo y el medio ambiente. Así, la aplicación de la nanotecnología a la ciencia dela conservación del patrimonio supone un importante avance que puede resolver muchos de los problemasencontrados en las intervenciones tradicionales de consolidación. Uno de los requisitos más importantespara el uso de estos productos en el patrimonio pétreo es la compatibilidad física y química con el sustratopétreo a tratar. Por esta razón, la presente investigación se basa en el diseño y el estudio de estabilidad deun nuevo producto consolidante, basado en nanopartículas de hidróxido de magnesio (brucita) con el finde consolidar y proteger los sustratos de carbonato de calcio-magnesio.Programas Geomateriales 2 (S2013/MIT-2914) y MultimatChallenge (S2013/MIT-2862