49 research outputs found

    Influence of process variables on the kinetic parameters of a Langmuir-Hinshelwood expression for E.coli inactivation during the photocatalytic disinfection of water

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    This research describes the effect of the photocatalyst concentration, irradiation power, concentration of inorganic salts and the initial pH on the three parameters of a Langmuir-Hinshelwood-model: inactivation kinetic constant; k, dimensionless interaction coefficient; K*, and inhibition coefficient; n, which was applied to the photocatalytic disinfection of water with TiO2. In general, there is a qualitative finding in the effects on parameters of some variables since an increase in k was always related to a decrease in K*. Such relation was observed for the amount of TiO2, the irradiation power and the increase in concentration of inorganic salts: NaCl and CaCO3. Moreover, increase in MgSO4 concentration do not cause a tendency of change on the described parameters. As for pH of the reaction media, an increasing effect on k is observed when its value promotes proximity between bacteria and TiO2 particles. Finally, small changes were observed for n with the studied variables, but indeed significant for mathematical fitting. Thus, these findings led to the formulation of a mathematical description of the effects of the most important variables and their interactions on the kinetic parameters. This last hypothesis was validated by comparison of experimental and predicted data with high correlations

    From an organometallic monolayer to an organic monolayer covered by metal nanoislands: A simple thermal protocol for the fabrication of the top contact electrode in molecular electronic devices

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    et al.In this contribution, a novel method for practical uses in the fabrication of the top contact electrode in a metal/organic monolayer/metal device is presented. The procedure involves the thermally induced decomposition of an organometallic compound, abbreviated as the TIDOC method. Monolayers incorporating the metal organic compounds (MOCs) [[4-{(4-carboxy)ethynyl}phenyl]ethynyl]-(triphenylphosphine)-gold, 1, or [1-isocyano-4-methoxybenzene]-[4-amino-phenylethynyl]-gold, 2, were annealed at moderate temperatures (1: 150 °C for 2h and 2: 100 °C for 2 h), resulting in cleavage of the Au-P or Au-C bond and reduction of Au(I) to Au(0) as metallic gold nanoparticles (GNPs). These particles are distributed on the surface of the film resulting in formation of metal/molecule/GNP sandwich structures. Electrical properties of these nascent devices were determined by recording I¿V curves with a conductive-AFM. The I¿V curves collected from these metal/organic monolayer/GNPs sandwich structures are typical of metal-molecule-metal junctions, with no low resistance traces characteristic of metallic short circuits observed over a wide range of set-point forces. The TIDOC method is therefore an effective procedure for the fabrication of molecular junctions for the emerging area of molecular electronics.Peer Reviewe

    Fabricación del electrodo superior en dispositivos moleculares mediante la formación de enlaces covalentes σ C-Au

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    Resumen del póster presentado a la 6ª Jornada de Jóvenes Investigadores en Física y Química de Aragón celebrada en Zaragoza el 20 de noviembre de 2014.-- et al.Peer reviewe

    El Currículum de la Titulación de Educación Especial: un análisis de las necesidades de formación inicial y de la formación permanente del Profesorado en ejercicio

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    The work that we present corresponds to the thrid stage of a Project of Educational Quality Improvement of the Faculty of Sciences of the Education of Cordoba initiated in 1999-2000 course. Its basic objective consists of contributing to the improvement and adjustement of curriculum for the degree of Maestro/a in Special Education through, in this case, the study of the demands of the educational demands shown by professionals who work in this specific field in educative centers of this province and the professional roles expected for the students of the specialty. Its necessity is justified, firstly, by the establishment of the existing divergence between the professional identity handled by the pupils of that specialty and its connection with the professional exigencies which they will have to face in the future and, secondly, if this divergence is stated, to cause the collective reflection of the university teaching staff on the professional models that are trasmitted and how to improve the educational task and the curricula in order to adapt them to the necessities and present social demands.El trabajo que presentamos corresponde a la tercera etapa de un Proyecto de Mejora de la Calidad Docente de la Facultad de Ciencias de la Educacion de Córdoba iniciado en el curso 1999-2000. Su objetivo básico consiste en contribuir al perfeccionamiento y adecuación del currículo formativo para la Titulación de Maestro/a en Educación Especial a través, en este caso, del estudio de las demandas de formación que manifiestan los profesionales que trabajan en este campo específico en centros educativos de esta provincia y los roles profesionales esperados por los y las estudiantes de la especialidad.Su necesidad de justifica, en primer lugar, por la constatación de la divergencia existente entre la identidad profesional que manejaba el Alumnado de esa especialidad y su conexión con las exigencias profesionales a las que deberán enfrentarse en el futuro y, en segundo, caso de constatarse esta divergencia provocar la reflexión colectiva del Profesorado universitario sobre los modelos profesionales que se transmiten y cómo mejorar el quehacer docente y los currículos al objeto de adecuarlos a las necesidades y demandas sociales actuales

    Desarrollo de una experiencia de mejora docente para la formación inicial del profesorado a través de la investigación-acción participativa con las TIC

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    La experiencia que presentamos se basa en la organización de dos asignaturas de la titulación de Magisterio alrededor de un diseño de investigación-acción participativa en el marco de un modelo de "comunidad de indagación". Nuestra comunidad está integrada por el alumnado y profesorado universitario junto con el profesorado y alumnado de Primaria del C.E.I.P. "Pablo García Baena" de Córdoba. El centro de Primaria participante inicia su andadura este año como Centro TIC y su claustro de profesorado nos propone que todos trabajemos alrededor de un tema de especial interés para este centro: "Hábitos de uso de las tecnologías de la información y comunicación por el alumnado de primaria". El objetivo es que nuestro alumnado universitario adquiera el dominio de herramientas profesionales básicas que le permitan diseñar estrategias adecuadas de recogida de información, análisis e intervención educativa en contextos naturales. Se trata, por tanto, de un marco de colaboración inter-institucional que beneficia la formación del alumnado de ambas instituciones y permite utilizar la información obtenida para promover procesos de mejora de la calidad educativa en el marco de los proyectos que desarrollan cada uno de los centrosThe study that we present here is based on the organization of two subjects of the degree in Education, concerning the design of participatory action research as part of a "community of inquiry". Our community comprises university students and teachers along with primary school teachers and students at the "Pablo Garcia Baena” Primary School in Córdoba. The school begins this year as an ICT Centre and its teachers' committee has suggested that we should collaborate on an issue of particular interest to the school: "Habits in the use of information and communication, technologies among pnmary school pupds". The goal is for our University students to master basic professional tools for the design of strategies for information gathering, analysis and training in natural educational contexts. This is thus a framework for inter-institutional collaboration that will benefit the training of students of both lnstitutions and enable all of us to use the information to improve the quallty of education in the context of development projects in both centres of educatio

    Towards a metallic top contact electrode in molecular electronic devices exhibiting a large surface coverage by photoreduction of silver cations

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    In this contribution the photoreduction of silver ions coordinated onto a Langmuir–Blodgett monolayer is presented as an effective method for the deposition of the top contact electrode in metal/monolayer/metal devices. Silver cations were incorporated from an aqueous AgNO3 sub-phase of Langmuir films of 4,4'-(1,4-phenylenebis(ethyne-2,1-diyl))dibenzoic acid upon the transference of these films onto a metallic substrate. Subsequent irradiation of the silver-ion functionalized Langmuir–Blodgett films with 254 nm light results in the photoreduction of silver cations to produce metallic silver nanoparticles, which are distributed over the organic monolayer and exhibit a surface coverage as large as 76% of the monolayer surface. Electrical properties of these metal/monolayer/metal devices were determined by recording I–V curves, which show a sigmoidal behaviour indicative of well-behaved junctions free of metallic filaments and short-circuits. The integrity of the organic monolayer upon the irradiation process and formation of the silver top-contact electrode has also been demonstrated through cyclic voltammetry experiments

    Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017

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    Background The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 comparative risk assessment (CRA) is a comprehensive approach to risk factor quantification that offers a useful tool for synthesising evidence on risks and risk–outcome associations. With each annual GBD study, we update the GBD CRA to incorporate improved methods, new risks and risk–outcome pairs, and new data on risk exposure levels and risk–outcome associations. Methods We used the CRA framework developed for previous iterations of GBD to estimate levels and trends in exposure, attributable deaths, and attributable disability-adjusted life-years (DALYs), by age group, sex, year, and location for 84 behavioural, environmental and occupational, and metabolic risks or groups of risks from 1990 to 2017. This study included 476 risk–outcome pairs that met the GBD study criteria for convincing or probable evidence of causation. We extracted relative risk and exposure estimates from 46 749 randomised controlled trials, cohort studies, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. Using the counterfactual scenario of theoretical minimum risk exposure level (TMREL), we estimated the portion of deaths and DALYs that could be attributed to a given risk. We explored the relationship between development and risk exposure by modelling the relationship between the Socio-demographic Index (SDI) and risk-weighted exposure prevalence and estimated expected levels of exposure and risk-attributable burden by SDI. Finally, we explored temporal changes in risk-attributable DALYs by decomposing those changes into six main component drivers of change as follows: (1) population growth; (2) changes in population age structures; (3) changes in exposure to environmental and occupational risks; (4) changes in exposure to behavioural risks; (5) changes in exposure to metabolic risks; and (6) changes due to all other factors, approximated as the risk-deleted death and DALY rates, where the risk-deleted rate is the rate that would be observed had we reduced the exposure levels to the TMREL for all risk factors included in GBD 2017. Findings In 2017, 34·1 million (95% uncertainty interval [UI] 33·3–35·0) deaths and 1·21 billion (1·14–1·28) DALYs were attributable to GBD risk factors. Globally, 61·0% (59·6–62·4) of deaths and 48·3% (46·3–50·2) of DALYs were attributed to the GBD 2017 risk factors. When ranked by risk-attributable DALYs, high systolic blood pressure (SBP) was the leading risk factor, accounting for 10·4 million (9·39–11·5) deaths and 218 million (198–237) DALYs, followed by smoking (7·10 million [6·83–7·37] deaths and 182 million [173–193] DALYs), high fasting plasma glucose (6·53 million [5·23–8·23] deaths and 171 million [144–201] DALYs), high body-mass index (BMI; 4·72 million [2·99–6·70] deaths and 148 million [98·6–202] DALYs), and short gestation for birthweight (1·43 million [1·36–1·51] deaths and 139 million [131–147] DALYs). In total, risk-attributable DALYs declined by 4·9% (3·3–6·5) between 2007 and 2017. In the absence of demographic changes (ie, population growth and ageing), changes in risk exposure and risk-deleted DALYs would have led to a 23·5% decline in DALYs during that period. Conversely, in the absence of changes in risk exposure and risk-deleted DALYs, demographic changes would have led to an 18·6% increase in DALYs during that period. The ratios of observed risk exposure levels to exposure levels expected based on SDI (O/E ratios) increased globally for unsafe drinking water and household air pollution between 1990 and 2017. This result suggests that development is occurring more rapidly than are changes in the underlying risk structure in a population. Conversely, nearly universal declines in O/E ratios for smoking and alcohol use indicate that, for a given SDI, exposure to these risks is declining. In 2017, the leading Level 4 risk factor for age-standardised DALY rates was high SBP in four super-regions: central Europe, eastern Europe, and central Asia; north Africa and Middle East; south Asia; and southeast Asia, east Asia, and Oceania. The leading risk factor in the high-income super-region was smoking, in Latin America and Caribbean was high BMI, and in sub-Saharan Africa was unsafe sex. O/E ratios for unsafe sex in sub-Saharan Africa were notably high, and those for alcohol use in north Africa and the Middle East were notably low. Interpretation By quantifying levels and trends in exposures to risk factors and the resulting disease burden, this assessment offers insight into where past policy and programme efforts might have been successful and highlights current priorities for public health action. Decreases in behavioural, environmental, and occupational risks have largely offset the effects of population growth and ageing, in relation to trends in absolute burden. Conversely, the combination of increasing metabolic risks and population ageing will probably continue to drive the increasing trends in non-communicable diseases at the global level, which presents both a public health challenge and opportunity. We see considerable spatiotemporal heterogeneity in levels of risk exposure and risk-attributable burden. Although levels of development underlie some of this heterogeneity, O/E ratios show risks for which countries are overperforming or underperforming relative to their level of development. As such, these ratios provide a benchmarking tool to help to focus local decision making. Our findings reinforce the importance of both risk exposure monitoring and epidemiological research to assess causal connections between risks and health outcomes, and they highlight the usefulness of the GBD study in synthesising data to draw comprehensive and robust conclusions that help to inform good policy and strategic health planning

    Erratum: Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017

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    Interpretation: By quantifying levels and trends in exposures to risk factors and the resulting disease burden, this assessment offers insight into where past policy and programme efforts might have been successful and highlights current priorities for public health action. Decreases in behavioural, environmental, and occupational risks have largely offset the effects of population growth and ageing, in relation to trends in absolute burden. Conversely, the combination of increasing metabolic risks and population ageing will probably continue to drive the increasing trends in non-communicable diseases at the global level, which presents both a public health challenge and opportunity. We see considerable spatiotemporal heterogeneity in levels of risk exposure and risk-attributable burden. Although levels of development underlie some of this heterogeneity, O/E ratios show risks for which countries are overperforming or underperforming relative to their level of development. As such, these ratios provide a benchmarking tool to help to focus local decision making. Our findings reinforce the importance of both risk exposure monitoring and epidemiological research to assess causal connections between risks and health outcomes, and they highlight the usefulness of the GBD study in synthesising data to draw comprehensive and robust conclusions that help to inform good policy and strategic health planning
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