1,720,963 research outputs found
L'influenza della gestione delle deiezioni sulla produzione di biogas negli allevamenti
No full textLa tecnologia utilizzata per la gestione delle deiezioni negli allevamenti intensivi di vacche da latte può influenzare la produzione di biogas e il contenuto di metano durante il successivo processo di digestione anaerobica. Una sperimentazione comparativa, della durata di 18 mesi, condotta in tre diverse aziende zootecniche lombarde, ha mostrato come le tecnologie più comuni (raschiatore, pavimentazione fessurata e flushing, ovvero lavaggio delle superfici con acqua) possano influenzare le proprietà delle deiezioni. Il raschiatore appare essere la scelta più neutrale, in quanto non modifica in modo rilevante le caratteristiche dei liquami e ne preserva il potenziale energetico. Il pavimento fessurato produce invece un liquame con una minore resa metanigena, principalmente a causa del fatto che la permanenza nella fossa di stoccaggio provoca una diminuzione dei solidi volatili e una modifica nella composizione della sostanza organica. Infine il flushing, che produce tre flussi distinti: liquame diluito, separato solido e separato liquido. Il liquame diluito non è compatibile con i reattori anaerobici convenzionali poiché la concentrazione di sostanza organica è troppo bassa per essere valorizzata. Il separato liquido può essere un materiale interessante in una eventuale co-digestione di biomasse ad alto tenore di solidi o in altri tipi di reattori, in quanto tende ad accumulare la sostanza organica solubile e quindi più facilmente biodegradabile. La frazione separata solida, infine, accumula sostanza organica inerte e la sua produzione specifica di metano risulta essere piuttosto bassa.Handling systems can influence the production of biogas and methane from dairy farm manures. A comparative work performed in three different Italian dairy farms showed how the most common techniques (scraper, slatted floor, flushing) can change the characteristics of collected manure. Scraper appears to be the most neutral choice, as it does not significantly affect the original characteristics of manure. Slatted floor produces a manure that has a lower methane potential in comparison with scraper, due to: a lower content of volatile solids caused by the biodegradation occurring in the deep pit, and a lower specific biogas production caused by the change in the characteristics of organic matter. Flushing can produce three different fluxes: diluted flushed manure, solid separated manure and liquid separated manure. The diluted fraction appears to be unsuitable for conventional anaerobic digestion in completely stirred reactors (CSTR), since its content of
organic matter is too low to be worthwhile. The liquid separated fraction could represent an interesting material, as it appears to accumulate the most biodegradable organic fraction, but not as primary substrate in CSTR as the organic matter concentration is too low. Finally, the solid-liquid separation process tends to accumulate inert matter in the solid separated fraction and, therefore, its specific methane production is low
Role of housing solutions in reducing GHG emissions from dairy cattle farms
No full textThe atmospheric emissions of CH 4 , N 2 O, CO 2 and NH 3 from four dairy farms with different dairy cows housing solutions were monitored by means of the "chamber method" procedure. Results show that the environmental impact of livestock units is higher in those farms where manure removal is provided with scraper on concrete floor. The addition of rubber mat in the alleys can improve the cleaning efficiency of scrapers and reduce NH 3 and CH 4 emissions. Lower emissions were observed in dairy houses equipped with slatted floor and/or flushing system for slurry removal
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
Adaptation of soil microorganisms to trace element contamination : a review of mechanisms, methodologies, and consequences for risk assessment and remediation
No full textThe authors provide an updated and integrated view of the adaptation of soil microorganisms to elevated concentrations of trace elements. Starting with a summary of the occurrence of trace elements in soils and their effects on soil microorganisms, the scientific evidence underlying adaptation of microorganisms to trace elements from species to community level is discussed. Insights are given regarding the main physiological processes involved in the resistance of bacteria to toxic elements including the potential importance of horizontal gene transfer in the adaptation process. The review continues with a discussion of how new molecular and biotechnological techniques can enrich this field of study. Scientific evidence is utilized in constructing an illustration of microbial community responses with reference to ecological indicators during various adaptation stages, while the related effects on community biological functionality and resilience are discussed. The authors conclude with an evaluation of the importance of considering adaptation in risk assessment and possible remediation of trace element-contaminated sites
Variations 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
The influence on biogas production of three slurry-handling systems in dairy farms
No full textHandling systems can influence the production of biogas and methane from dairy farm manures. A comparative work performed in three different Italian dairy farms showed how the most common techniques (scraper, slatted floor, flushing) can change the characteristics of collected manure. Scraper appears to be the most neutral choice, as it does not significantly affect the original characteristics of manure. Slatted floor produces a manure that has a lower methane potential in comparison with scraper, due to: a lower content of volatile solids caused by the biodegradation occurring in the deep pit, and a lower specific biogas production caused by the change in the characteristics of organic matter. Flushing can produce three different fluxes: diluted flushed manure, solid separated manure and liquid separated manure. The diluted fraction appears to be unsuitable for conventional anaerobic digestion in completely stirred reactors (CSTR), since its content of organic matter is too low to be worthwhile. The liquid separated fraction could represent an interesting material, as it appears to accumulate the most biodegradable organic fraction, but not as primary substrate in CSTR as the organic matter concentration is too low. Finally, the solid-liquid separation process tends to accumulate inert matter in the solid separated fraction and, therefore, its specific methane production is low
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Potential nitrification, nitrate reductase, and β-galactosidase activities as indicators of restoration of ecological functions in a Zn contaminated soil.
No full texthe present study was conducted to assess the possible restoration of different ecological functions in a Zn- contaminated soil. Experiments were conducted in a soil microcosm contaminated with 350 mg kg−1 of Zn and in an uncontaminated control microcosm, both incubated for 4 months. At regular intervals, potential nitrification, nitrate reductase, and β-galactosidase activity were determined. All these activities were significantly reduced just after Zn contamination in contaminated microcosms compared to the activities of the control, but then increased. In order to confirm that the restoration of ecological functions was not due to an aging phenomenon, a reinoculation protocol was also applied. A significant restoration was found for β-galactosidase activity, while for nitrate re- ductase activity and potential nitrification, there was a clear shift of dose–response curves but with partial over- lap of the EC50 ranges estimation, thus indicating that different ecological functions are restored over time in Zn-contaminated soils
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