1,721,155 research outputs found
Bench scale PAA disinfection tests: evaluation of operating parameters
No full textThe feasibility of using peracetic acid (PAA) for wastewater disinfection, both for discharge into surface waters and agricultural reuse, was tested with reference to F. coli and E. coli as process efficiency indicators. PAA decay kinetics was evaluated in tap water and wastewater, in order to correlate PAA consumption to the physicochemical characteristics of the influent treated wastewater. In both cases, PAA decays according to a first order kinetics, with respect to time, and no apparent correlation was found between PAA consumption and wastewater initial characteristics. The sensitivity to PAA of the 2 microbial indicators was evaluated comparing log-survival ratios: F. coli was found to be less resistant than E. coli, which therefore appears not to be adequate to describe process efficiency. PAA disinfection efficiency was correlated with operating parameters (active concentration and contact time), testing different kinetic models (Chick-Watson, Selleck, Hom), which are commonly used for disinfection treatment design; a relationship specifically built for PAA (S-model) was also tested. Hom’s model was found to best fit experimental data in whole, while S-model, on the contrary, allows to better explain initial resistance of E. coli, especially at low PAA active concentrations (< 2 mg/L) and short contact times (< 12 min)
The Sky on Earth project: a synergy between formal and informal astronomy education
No full textIn this paper we present the Sky on Earth project funded in 2008 by the Italian Ministry of Instruction, Research and University, inside the annual public outreach education program. The project’s goal was to realize an open-access and stable astronomical garden, where children, teachers and citizens could be engaged in investigations about day and night sky phenomena. The project was designed taking into account our prior researches in formal and informal astronomy education, and realized in the garden of GiocheriaLaboratori. This is an educational structure of Sesto San Giovanni municipality (near Milan, Italy), we are collaborating with for long time, devoted to out-of-school K-6 science education since 1987. Setting and tools were designed with the help of a group of students of the “Altiero Spinelli” vocational school and their science and technology teachers. Since its installation, the astronomical garden has been used in workshops and open-days, teachers’ preparation courses and research experiences. We might conclude that the Sky on Earth project represents an example of a positive and constructive collaboration between researchers, educators, high school students and teachers. It may also be considered as a potential attempt to face on the well-known gap between research in science education and school practices
PAA disinfection: a feasible alternative to wastewater chlorination
No full textThe paper summarizes the results of a bench scale study to evaluate the feasibility of using peracetic acid (PAA) as substitute for sodium hypochlorite both for discharge into surface water and for agricultural reuse. Trials were carried out with increasing doses (1, 2, 3, 5, 10 and 15 mg/L) and contact times (6, 12, 18, 36, 42, 54 min) to study disinfectant decay and bacterial removal and re-growth, using F. coli and E. coli as process efficiency indicators. PAA decay kinetics was evaluated in tap water and wastewater: in both cases, PAA decays according to a first order kinetics with respect to time, and a correlation was found between PAA oxidative initial consumption and wastewater characteristics.
PAA disinfection efficiency was correlated with operating parameters (active concentration and contact time), testing different kinetic models. Two data groups displaying a different behavior on the basis of initial active concentration’s ranges, respectively 1÷2 mg/L and 5÷15 mg/L, can be outlined. Both groups had a “tailing off” inactivation curve with respect to time, but the second one showed a greater inactivation rate. Moreover the effect of contact time was greater at the lower doses.
Hom’s model, used separately for the two data groups, was found to best fit experimental data and the disinfectant active concentration appears to be the main factor affecting log-survival ratios. Moreover S-model allows to better explain initial resistance of E. coli, especially at low active concentrations (< 2 mg/L) and short contact times (< 12 min).
Microbial counts, performed by both traditional methods and flow cytometry, immediately and 5 hours after the sample collection (both with or without residual PAA inactivation), showed that no appreciable re-growth took place after 5 hours neither for coliform group bacteria nor for total heterotrophic bacteria (THB)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Microinquinanti prioritari nel settore della nobilitazione tessile: il distretto comasco
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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