Fe vs. TiO2 Photo-assisted Processes for Enhancing the Solar Inactivation of Bacteria in Water

Batch solar water disinfection (SODIS) is a known, simple and low-cost water treatment technology. SODIS is based on the synergistic action of temperature increase and light-assisted generation of Reactive Oxygen Species (ROS) on bacteria. ROS are generated via the action of solar photons on i) Natural Organic Matter (NOM), ii) some mineral components of water (Fe oxides or Fe-organic complexes, nitrogen compounds) and iii) endogenous bacteria photosensitizers (e.g. cytochrome). SODIS has proven its effectiveness for remote settlements or urban slums in regions with high incident solar radiation. All of the internal and external simultaneous processes are often driven by photoactive Fe-species present in the cell, as well as in the natural water sources. In SODIS, a temperature of 50 °C is required and due to this temperature dependence, only 1–2 L can be treated at a time. As required exposure time strongly depends on irradiation intensity and temperature, some SODIS households could be overburdened, leading to inadequate treatment and probable bacterial re-growth. This is why TiO2 photocatalysis and Fe photo-assisted systems (i.e. photo-Fenton reactants) have been considered to enhance the photo-catalytic processes already present in natural water sources when exposed to solar light. Both TiO2 and Fe-photoassisted processes, when applied to water disinfection aim to improve the performance of solar bacteria inactivation systems by i) enhancing ROS production, ii) making the process independent from the rise in temperature and as a consequence iii) allowing the treatment of larger volumes than 1–2 L of water and iv) prevent bacterial (re)growth, sometimes observed after sole solar treatment

Overview on Photocatalytic and Electrocatalytic Pretreatment of Industrial Non-Biodegradable Pollutants and Pesticides

Electrochemical and photochemical catalytic pretreatments were studied on diverse non-biodegradable industrial or toxic pollutants using different catalysts. This approach turned out also to be useful to degrade recalcitrant industrial waste waters markedly enhancing the biodegradability and biocompatibility of the treated effluents. In the case of p-toluenesulfonate, a completely non-biodegradable material from the dye industry, the TiO2 photocatalytic material applied for two hours affected total dearomatization allowing efficient subsequent biological degradation. A photochemical-biological flow reactor has been built to attain full mineralization of large volumes of diluted solutions of this xenobiotics as found in polluted water reservoirs. Fenton and photo-Fenton systems have been extensively studied in the abatement of the highly soluble Orange azo-dyes. They induce rapid destructive and low cost degradation of these textile dyes comparable to flocculation/coagulation techniques

OPTOGENETIC GUIDE RNA PRODUCTION FOR SPATIOTEMPORAL REGULATION OF CRISPR/CAS SYSTEMS

OPTOGENETIC GUIDE RNA PRODUCTION FOR SPATIOTEMPORAL REGULATION OF CRISPR/CAS SYSTEM

Ultrasound enhancement of near-neutral photo-Fenton for effective E. coli inactivation in wastewater

In this study, we attempt for the first time to couple sonication and photo-Fenton for bacterial inactivation of secondary treated effluent. Synthetic wastewater was subjected to sequential high-frequency/low power sonication, followed by mild photo-Fenton treatment, under a solar simulator. It was followed by the assessment of the contribution of each component of the process (Fenton, US, hv) towards the removal rate and the long-term survival; sunlight greatly improved the treatment efficiency, with the coupled process being the only one to yield total inactivation within the 4-h period of treatment. The short-term beneficial disinfecting action of US and its detrimental effect on bacterial survival in long term, as well as the impact of light addition were also revealed. Finally, an investigation on the operational parameters of the process was performed, to investigate possible improvement and/or limitations of the coupled treatment; 3 levels of each parameter involved (hydraulic, environmental, US and Fenton) were tested. Only H2O2 increased improved the process significantly, but the action mode of the joint process indicated potential cost-effective solutions towards the implementation of this method. (C) 2014 Elsevier B.V. All rights reserved.Preprin

Inactivation of bacteria under visible light and in the dark by Cu films. Advantages of Cu-HIPIMS-sputtered films

Introduction: The Cu polyester thin-sputtered layers on textile fabrics show an acceptable bacterial inactivation kinetics using sputtering methods. Materials and methods: Direct current magnetron sputtering (DCMS) for 40s of Cu on cotton inactivated Escherichia coli within 30min under visible light and within 120min in the dark. For a longer DCMS time of 180s, the Cu content was 0.294% w/w, but the bacterial inactivation kinetics under light was observed within 30min, as was the case for the 40-s sputtered sample. Results and discussion: This observation suggests that Cu ionic species play a key role in the E. coli inactivation and these species were further identified by X-ray photoelectron spectroscopy (XPS). The 40-s sputtered samples present the highest amount of Cu sites held in exposed positions interacting on the cotton with E. coli. Cu DC magnetron sputtering leads to thin metallic semi-transparent gray-brown Cu coating composed by Cu nanoparticulate in the nanometer range as found by electron microscopy (EM). Cu cotton fabrics were also functionalized by bipolar asymmetric DCMSP. Conclusion: Sputtering by DCMS and DCMSP for longer times lead to darker and more compact Cu films as detected by diffuse reflectance spectroscopy and EM. Cu is deposited on the polyester in the form of Cu2O and CuO as quantified by XPS. The redox interfacial reactions during bacterial inactivation involve changes in the Cu oxidation states and in the oxidation intermediates and were followed by XPS. High-power impulse magnetron sputtering (HIPIMS)-sputtered films show a low rugosity indicating that the texture of the Cu nanoparticulate films were smooth. The values of R q and R a were similar before and after the E. coli inactivation providing evidence for the stability of the HIPIMS-deposited Cu films. The Cu loading percentage required in the Cu films sputtered by HIPIMS to inactivate E. coli was about three times lower compared to DCMS films. This indicates a substantial Cu metal savings within the preparation of antibacterial film

Sobre las interacciones en el proceso de enseñanza y aprendizaje

Este número de Reflexiones Pedagógicas URosario tiene como propósito introducir el tema de las interacciones como parte fundamental en el proceso de enseñanza y aprendizaje. Varios autores han considerado el tema de la interacción como condición para aprender; en este texto nos adentraremos en el estudio de las propuestas de algunos de ellos y reconoceremos que es un reto generar ambientes de aprendizaje que las propicien. Sabemos que es un camino posible que ya están recorriendo algunos profesores de la Universidad. ¡Esperamos que cada vez sean más

Perspective on the use of b-on digital library by higher education teaching staff – the study case of Polytechnic Institute of Castelo Branco (Portugal)

Este trabalho de investigação pretende mostrar a visão que os docentes/investigadores de uma instituição de ensino superior (IES), o Instituto Politécnico de Castelo Branco (IPCB) têm sobre a biblioteca digital b-on, designadamente se a conhecem, utilizam, como acedem e com que frequência, como a classificam do ponto de vista dos conteúdose qual o grau de complexidade que lhe imputam. A sua realização fundamenta-se na necessidade de compreender a razão pela qual os níveis de utilização da b-on no IPCB, ao longo dos últimos anos sãobaixosem sequência, desenvolver estratégias que ajudem a melhorar estes níveis. Para realizar o estudo recorreu-se à distribuição de um inquérito por questionário a todos os docentes/investigadores (n=288) do IPCB tendo-se obtido uma amostra de 33,7%. Os docentes/investigadores foram agrupados segundo as áreas científicas da Fundação para a Ciência e a Tecnologia (FCT), considerando a área de investigação atual.Os dados foram tratados com recurso aoprograma SPSS.Determinaram-se as percentagens e,em alguns casos,calculou-se a média e o desvio padrão.Verificou-se que94,0% dos respondentesconhecem a b-on, embora apenas 82,9% indique utilizá-la.Verificou-se, também que, de um modo geral, os docentes/investigadores classificam a b-on, nos diversos parâmetros, com valores superiores a 3,5, numa escala de 1 a 5 sendo que,maioritariamente, indicam os artigos científicos como a tipologia de documentos mais utilizados para realização de trabalho de investigação.A b-on é a segunda ferramenta mais utilizada para localizar documentos científicos mas é o recurso mais utilizado para descarregar documentos científicos. Dos respondentes, 89,6% indicaram necessidade de formação para utilizar bem o recurso e 57,0% indicaram que a formação deve ser obrigatória. Conclui-se que a maioria dos docentes conhece e utiliza a b-on, todavia a frequência com que a utiliza é baixa. Verifica-se também que os docentes que não utilizam ou que utilizam menos são da área Científica das Ciências Sociais e das Humanidades incluindo as Artes (CSHiA) o que pode estar relacionado com a disponibilidade de conteúdos. Constata-se ainda que a b-on é uma ferramenta dotada de alguma complexidade na medida em que a maioria dos docentes/investigadores consideram a necessidade de formação para bema utilizar e que deve ser o bibliotecário a ministrar essa formação.ABstract: Present work aims to know how teachers and researchers from the Polytechnic Institute of Castelo Branco (PICB) uses the digital library b-on, namely if they know it, how they use it, how they accede, and how often they use it, its value and if they find it is difficult to utilize. It was based on the need of understanding the low levels of its use despite being the more important digital resource of PICB and in sequence to develop strategies that allow to reverse this situation. Is was done using a survey that was distributed among all teachers and researchers (ETI) (n=288). 33,3% of valid answers were obtained. The respondents were grouped following the scientific areas of the Portuguese Foundation for Science and Technology. Data were processed with SPSS program. The percentages were determined and, in some cases, the mean and standard deviation were calculated. It was verified that 94.0% of the respondents know the b-on, although only 82.9% indicate to use it. It was also verified that, in a general way, the teachers / researchers classify the b-on, in the several parameters, with values greater than 3.5, in a scale of 1 to 5 and, in the main, they indicate the scientific articles as the typology of documents most used to carry out research work. B-on is the second most commonly used tool for locating scientific documents but it is the most widely used resource for downloading scientific documents. Of the respondents, 89.6% indicated a need for training to use the resource well and 57.0% indicated that training should be compulsory. It is concluded that most teachers know and use b-on, but the frequency with which they use it is low. It is also verified that teachers who do not use or use less are from the Social Sciences and Humanities Scientific Domain including the Arts (CSHiA) which may be related to the availability of contents. It is also noted that b-on is a tool with some complexity in that most of the teachers / researchers consider the need for training to be used and that the librarian should provide this training.info:eu-repo/semantics/publishedVersio

Narrativas transmedia y aprendizaje colaborativo : El caso de los estudiantes de la asignatura teorías de la imagen de la Licenciatura en Comunicación e Informática Educativas, adscrita a la Universidad Tecnológica de Pereira

Teniendo en cuenta que asistimos a un contexto en el que las plataformas se multiplican y las narrativas se expanden y enriquecen día a día, y que la manera de contar y crear dichas historias cambian, permitiendo cada vez más la participación de los individuos del orden social; y que sin lugar a dudas asistimos a un nuevo paradigma comunicativo en el que la educación apenas encuentra luces para operar en estas nuevas dinámicas; consideramos pertinente y oportuno continuar con las investigaciones sobre el campo de las narrativas transmedia como ambiente de aprendizaje en la educación formal, ya que estas pretenden ser facilitadoras de ambientes propicios para el desarrollo de estrategias y didácticas relevantes en diversos ambientes de aprendizaje; por lo que el presente proyecto tiene como propósito responder a la siguiente pregunta de investigación: ¿Cuál es la relación entre las narrativas transmedia y los procesos de aprendizaje colaborativo de los estudiantes de la asignatura teorías de la imagen de la Licenciatura en Comunicación e Informática Educativas de la Universidad Tecnológica de Pereira? Es por lo anterior que los ejes principales del marco teórico que transversalizan nuestro proyecto investigativo, corresponde a los planteamientos y postulados de Carlos Scolari sobre las narrativas transmedia, y de la antropología del ciberespacio y las inteligencias colectivas de Pierre Levy, con el fin de sustentar las diversas fases que corresponden a nuestros objetivos específicos, para de esta forma acercarnos tanto a la pregunta que sustenta nuestra labor investigativa como, el fenómeno que se pretende investigar de modo preciso

The bactericidal effect of TiO2 photocatalysis involves adsorption onto catalyst and the loss of membrane integrity

The bactericidal effect of photocatalysis with TiO2 is well recognized, although its mode of action is still poorly characterized. It may involve oxidation, as illuminated TiO2 generates reactive oxygen species. Here we analyze the bactericidal effect of illuminated TiO2 in NaCl-KCl or sodium phosphate solutions. We found that adsorption of bacteria on the catalyst occurred immediately in NaCl-KCl solution, whereas it was delayed in the sodium phosphate solution. We also show that the rate of adsorption of cells onto TiO2 is positively correlated with its bactericidal effect. Importantly, adsorption was consistently associated with a reduction or loss of bacterial membrane integrity, as revealed by flow cytometry. Our work suggests that adsorption of cells onto aggregated TiO2, followed by loss of membrane integrity, is key to the bactericidal effect of photocatalysi