Pressure-induced transformations in LiCl–H2O at 77 K

A systematic study of the properties of high-density amorphous ice (HDA) in the presence of increasing amounts of salt is missing, especially because it is challenging to avoid ice crystallization upon cooling the pressurized liquid. In order to be able to study HDA also in the presence of small amounts of salt, we have investigated the transformation behaviour of quenched aqueous LiCl solutions (mole fraction x 1 GPa. The observed densification is consistent with the idea that a freeze concentrated LiCl solution of x = 0.14 (R = 6) segregates, which transforms to the glassy state upon cooling, and that the densification is only due to the Ih → HDA transition. Also the XRD patterns and DSC scans are almost unaffected by the presence of the segregated glassy LiCl solution. Upon heating at ambient pressure HDA experiences the polyamorphic transition to low-density amorphous ice (LDA) at ∼120 K, even at x ∼ 0.10. Based on the latent heat evolved in the transition we suggest that almost all water in the sample transforms to an LDA-like state, even the water in the vicinity of the ions. The glassy LiCl solution acts as a spectator that does not shift the transformation temperature significantly and experiences a glass-to-liquid transition at ∼140 K prior to the crystallization to cubic ice. By contrast, at x > 0.12 the phenomenology completely changes and is now dominated by the salt. Hexagonal ice no longer forms upon quenching the LiCl solution, but instead LDA forms. A broad pressure-induced transformation at >0.6 GPa can be attributed to the densification of LDA, the glassy LiCl solution and/or glassy hydrates.Fil: Ruiz, G. N.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Innsbruck; AustriaFil: Bove, L. E.. Universite Pierre et Marie Curie; Francia. Ecole Polytechnique Federale de Lausanne; SuizaFil: Corti, Horacio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Loerting, T.. Universidad de Innsbruck; Austri

Constituyentes Orgánicos Volátiles de Clinopodium gilliesii (Benth.) Kuntze: Análisis por HS-SPME e hidrodestilación clásica

In the present research, an analytical methodology to micro scale based on the use of the HS-SPME/GC-MS to determine volatile compounds present in Clinopodium gilliesii (Benth.) Kuntze (Lamiaceae) was employed, and settled differences and similarities with its essential oil obtained by hydrodistillation. A systematic description of the volatile components of flowers, stems, leaves and combined aerial parts (whole plant) was constructed via GC-MS analyses of HS-SPME adsorbed compounds and of essential oils obtained through hydrodistillation of the same tissues. Piperitenone oxide and piperitone oxide were the main components of both the HS-SPME analysis and essential oil analysis. The HS-SPME method can achieve comparable results to those obtained by essential oil analysis, by using very fewer samples, a shorter extraction time and a much simpler procedure.  Para citar este artículoVázquez, A., Aimar, M.,Decarlini, M., Demmel, G., Cantero, J y Ruiz, G. (2016). Volatile Organic Constituents of Clinopodium gilliesii (Benth.) Kuntze: Analysis by HS-SPME and classic hydrodistillation. Rev. Colomb. Investig. Agroindustriales, 3(1), 91-100. DOI: http://dx.doi.org/10.23850/24220582.351In the present research, an analytical methodology to micro scale based on the use of the HS-SPME/GC-MS to determine volatile compounds present in Clinopodium gilliesii (Benth.) Kuntze (Lamiaceae) was employed, and settled differences and similarities with its essential oil obtained by hydrodistillation. A systematic description of the volatile components of flowers, stems, leaves and combined aerial parts (whole plant) was constructed via GC-MS analyses of HS-SPME adsorbed compounds and of essential oils obtained through hydrodistillation of the same tissues. Piperitenone oxide and piperitone oxide were the main components of both the HS-SPME analysis and essential oil analysis. The HS-SPME method can achieve comparable results to those obtained by essential oil analysis, by using very fewer samples, a shorter extraction time and a much simpler procedure  Para citar este artículoVázquez, A., Aimar, M.,Decarlini, M., Demmel, G., Cantero, J y Ruiz, G. (2016). Volatile Organic Constituents of Clinopodium gilliesii (Benth.) Kuntze: Analysis by HS-SPME and classic hydrodistillation. Rev. Colomb. Investig. Agroindustriales, 3(1), 91-100. DOI: http://dx.doi.org/10.23850/24220582.351En el presente trabajo se empleó una metodología analítica a micro-escala basada en HS-SPME/GC-MS, para determinar los compuestos volátiles presentes en Clinopodium gilliesii (Benth.) Kuntze (Lamiaceae), y se establecieron diferencias y similitudes con su aceite esencial obtenido por hidrodestilación. Se realizó una descripción sistemática de los componentes volátiles de flores, tallos, hojas y partes aéreas combinadas (planta entera) a partir de los análisis por GC-MS, a través del sistema HS-SPME y de los aceites esenciales. La piperitenona y el óxido de piperitona fueron los componentes principales tanto del análisis por HS-SPME, como del aceite esencial. El método de HS-SPME puede lograr resultados comparables a los obtenidos por el análisis de aceite esencial, mediante el uso de muestras de menor tamaño, un tiempo de extracción más corto y un procedimiento más simple.  Para citar este artículoVázquez, A., Aimar, M.,Decarlini, M., Demmel, G., Cantero, J y Ruiz, G. (2016). Volatile Organic Constituents of Clinopodium gilliesii (Benth.) Kuntze: Analysis by HS-SPME and classic hydrodistillation. Rev. Colomb. Investig. Agroindustriales, 3(1), 91-100. DOI: http://dx.doi.org/10.23850/24220582.35

Finding an apprenticeship : hidden curriculum and social consequences

In Switzerland, the majority of students are oriented towards professional training after compulsory schooling. At this stage, one of the biggest challenges for them is to find an apprenticeship position. Matching supply and demand is a complex process that not only excludes some students from having direct access to professional training but also forces them to make early choices regarding their future sector of employment. So, how does one find an apprenticeship? And what do the students' descriptions of their search for apprenticeships reveal about the institutional determinants of social inequalities at play in the system? Based on 29 interviews conducted in 2014 with 23 apprentices and 6 recruiters in the Canton of Vaud, this article interrogates how the dimensions of educational and social trajectories combine to affect access to apprenticeships and are accentuated by recruiters using a "hidden curriculum" during the recruitment process. A hidden curriculum consists of knowledge and skills not taught by the educational institution but which appear decisive in obtaining an apprenticeship. By analysing the contrasting experiences of students in their search for an apprenticeship, we identify four types of trajectories that explain different types of school-to-apprenticeship transitions. We show how these determinants are reinforced by the "hidden curriculum" of recruitment based on the soft skills of feeling, autonomy, anticipation and reflexivity that are assessed in the context of recruitment interactions. The discussion section debates how the criteria that appear to be used to identify the "right apprentice" tend to (re)produce inequalities between students. This not only depends on their academic results but also on their social and cultural skills, their ability to anticipate their choices and, more widely, their ability to be a subject in their recruitment search. "The Subject is neither the individual, nor the self, but the work through which an individual transforms into an actor, meaning an agent able to transform his/her situation instead of reproducing it." (Touraine, 1992, p.476)

Anthropic impact assessment of coastal ecosystems in the municipality of Puerto Colombia, NE Colombia

Bolívar, M.; Rivillas-Ospina, G.; Fuentes, W.; Guzmán, A.; Otero, L.; Ruiz, G.; Silva, R.; Mendoza, E.; Maza, M.; García, L., and Berrío, Y., 2019. Anthropic impact assessment on coastal ecosystems in the municipality of Puerto Colombia, NE Colombia. In: Silva, R.; Martínez, M.L.; Chávez, V., and Lithgow, D. (eds.), Integrating Biophysical Components in Coastal Engineering Practices. Journal of Coastal Research, Special Issue No. 92, pp. 112–120. Coconut Creek (Florida), ISSN 0749-0208. Human activity, mainly associated with the construction of coastal infrastructure, has caused ecological degradation to the coastal zone at Puerto Colombia, Colombia. Severe erosion attacked the ancient sandy spit that protected the municipality from wave energy to an extent that it completely disappeared. The groins constructed thereafter, with the aim of protecting the coast, have exacerbated the sediment imbalance, affecting the Balboa coastal wetland. At present, the coastline around Puerto Colombia is highly vulnerable; the remaining ecosystems are under severe pressure, and the population is at risk. Restoring the marine and terrestrial connectivity is key to improving this situation. ©Coastal Education and Research Foundation, Inc. 2019

Shortcut biological nitrogen removal (SBNR) in microbial fuel cells (MFCs)

Microbial Fuel Cells (MFCs) represent nowadays a promising technology for the treatment of industrial wastewater. In this work the Shortcut Nitritation/Denitritation process in H-type MFC was investigated. The cell was fed by sodium acetate and fumaric acid, as organic carbon source, and ammonium sulphate, sodium nitrite and sodium nitrate as nitrogen source. Anaerobic digestion supernatant (digestate) was used as bacterial source. Batch tests were performed at a TOC/N ratio of 0.35, and Total Organic Carbon (TOC), pH and Open Circuit Voltage (OCV) were daily monitored. High organic carbon removal (up to 85%) in short time (within 6 days) were achieved. The nitritation proved to be independent of organic carbon amount and composition: an ammonium content reduction of about 45% was observed. Regarding the denitritation step, an almost quantitative removal of nitrite and nitrate was observed when fumaric acid was used as a carbon source

Diseño de un proyecto de investigación básico

Nos proponemos que los estudiantes entren en contacto con las actividades de investigación y que, de manera autónoma, aunque guiados por el profesor, encuentren la respuesta a una pregunta mediante el desarrollo del método científico, haciendo uso también de unos procedimientos básicos para la elaboración de un proyecto de investigación.We propose that the students come in contact with the activities of research and that, in an autonomous manner, while guided by the professor, to find the answer to a question through the development of the scientific method, by using a few basic procedures for the preparation of a research project

Analysis of CMB maps with 2D wavelets

We consider the 2D wavelet transform with two scales to study sky maps of temperature anisotropies in the cosmic microwave background radiation (CMB). We apply this technique to simulated maps of small sky patches of size 12.8 \times 12.8 square degrees and 1.5' \times 1.5' pixels. The relation to the standard approach, based on the cl's is established through the introduction of the scalogram. We consider temperature fluctuations derived from standard, open and flat-Lambda CDM models. We analyze CMB anisotropies maps plus uncorrelated Gaussian noise (uniform and non-uniform) at idfferent S/N levels. We explore in detail the denoising of such maps and compare the results with other techniques already proposed in the literature. Wavelet methods provide a good reconstruction of the image and power spectrum. Moreover, they are faster than previously proposed methods.Comment: latex file 7 pages + 5 postscript files + 1 gif file; accepted for publication in A&A