1,720,969 research outputs found
Urban organic waste valorization through an integrated pilot scale biorefinery for polyhydroxyalkanoates and biogas production
No full textThe main three-year doctoral research activity is centered around the pilot scale implementation of a biorefinery aimed at the valorization of organic waste into polyhydroxyalkanoates (PHAs) and biogas. The whole production chain comprises the organic waste fermentation, the aerobic line for PHA production and the anaerobic co-digestion of the secondary waste streams produced within the biorefinery. A mixture of organic fraction of municipal solid waste and waste activated sludge from the municipal wastewater treatment was used as primary carbon source. The initial phases of the study focused on the fermentation process and the aerobic line, the most performing conditions corresponded to a fermentation yield (YVFA) equal to 0.40 g CODVFA/g VS and a storage yield in the accumulation phase (YP/VFAbatch) equal to 0.50 CODPHA/CODVFA. Then, the studies focused on the anaerobic line, i.e. the acidogenic fermentation and anaerobic co-digestion. Following studies aimed at the optimization of the fermentation process, the best obtained yields guaranteed a YVFA of 0.57 and 0.74 gCODVFA/g VS in batch and continuous tests respectively. The most performing conditions were then tested at pilot scale, the overall yield was considerably increased, reaching 76 g PHA/kg VS. In addition, legislative barriers and product social acceptance of waste derived bioplastics were preliminarily investigated. As final optimization, different operating conditions were investigated in the MMCs PHA selection process, that allowed to reach further improvement of the biorefinery overall yield, equal to 110 g PHA/kg VS. The results obtained in the present thesis shed a light on promising innovations in the field of organic waste valorization, proving the feasibility of the whole productive chain and its future industrial scale implementation
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
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
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
Una bioraffineria urbana per la conversione della frazione organica dei rifiuti solidi urbani (FORSU) e fanghi municipali in biopolimeri e biogas
No full textUna bioraffineria urbana in scala pilota è stata sviluppata nel contesto territoriale del comune di Treviso (TV) per la produzione di biopolimeri (poliidrossialcanoati, PHA) e biogas da rifiuti organici urbani. In tale contesto, la raccolta differenziata altamente efficiente (87,9% sui rifiuti totali) garantisce la produzione di Frazione Organica di Rifiuti Solidi Urbani (FORSU) di alta qualità (alto contenuto organico biologicamente valorizzabile). Attualmente, la frazione liquida proveniente dal pre-trattamento meccanico della FORSU viene miscelata con fango biologico secondario (WAS) ed inviata al co-digestore anaerobico (ACoD) in piena scala all’interno dell’impianto di trattamento acque (WWTP) di Treviso (70.000 PE) per la produzione di solo biogas. Il sistema sviluppato in scala pilota (100-380 L) prevede l’upgrade dello schema attualmente operativo in piena scala tramite l’installazione di una linea aerobica per la produzione di PHA.
Le unità pilota sono le seguenti: a) fermentatore acidogenico per la produzione di acidi grassi volatili (VFA); b) separazione solido/liquido (membrana tubolare di ultrafiltrazione); c) un Sequencing Batch Reactor (SBR) per la produzione aerobica di biomassa mista (MMC) PHAproduttrice; d) reattore aerobico fed-batch per la produzione intracellulare di PHA; e) ACoD per la produzione di biogas dai residui solidi miscelati con WAS prodotto dall’impianto in piena scala. FORSU pressata e WAS sono stati miscelati in una frazione volumetrica del 30% e 70% rispettivamente. La fermentazione acidogenica è stata condotta dopo un prepretrattamento termico (72°C, 48 ore), in modalità batch (5 d) e in mesofilia (37°C). Il processo fermentativo avveniva in un intervallo di pH compreso tra 5.0-5.5 ed era caratterizzato da un rendimento (YVFA) medio pari a 0.43 g CODVFA/g VS(0). La concentrazione di VFA in uscita era pari a 30 g CODVFA/L, con un rapporto CODVFA/CODSOL di 0.84. Questa caratteristica fondamentale della matrice fermentata permetteva di condurre la selezione aerobica della biomassa PHA-accumulante, la cui crescita è garantita dalla presenza di VFA, in modo efficace. Il reattore SBR è stato mantenuto operativo per più di 8 mesi, applicando un OLR di 3.2-4.0 kg COD/m3 .d e HRT pari a 1.0 d (uguale a SRT). La biomassa selezionata era in grado di accumulare fino al 60% di PHA rispetto al suo peso secco (w/w).
In relazione al rifiuto organico di partenza, è stato stimato un rendimento complessivo di 107 g PHA/kg VS (approssimativamente del 10%). Il processo mesofilo (37°C) di codigestione (HRT 15-18 d, OLR 2-2.5 kg VS/m3 .d) ha permesso di produrre biogas dai flussi secondari in eccesso ricchi in solidi (30% w/w TS) dopo diluizione con WAS. La produzione specifica di gas (SGP) era pari a 0.4 m3 /kg VS.
Applicando tale bioraffineria all’attuale impianto in piena scala è stata stimata una produzione di 114 ton PHA/y, 2314 m3 biogas/d e 5.9 MWh/d di energia elettrica. Rispetto allo scenario ACoD attuale, questo schema può essere ugualmente redditizio se il PHA prodotto è commercializzato ad una soglia minima di 0.82 €/kg. Quindi, un prezzo di mercato più alto e ancora ragionevole potrebbe rendere la bioraffineria un modello di valorizzazione dei rifiuti urbani preferibile rispetto al tradizionale approccio di digestione anaerobica
Aloysia citrodora Polyphenolic Extract: From Anti-Glycative Activity to In Vitro Bioaccessibility and In Silico Studies
Full text linkBackground: The in vivo accumulation of Advanced Glycation End products (AGEs)
is associated with the development of several chronic aging-related and degenerative
diseases, as they alter protein structures and activate oxidative and inflammatory processes
through interactions with the receptor for AGEs (RAGE). Plant secondary metabolites
play a key role in counteracting the glycation process through various mechanisms of
action. Therefore, Aloysia citrodora leaf polyphenolic extract could represent a source
of anti-glycative compounds. Methods: The methanolic extract was characterized by
RP-HPLC-DAD-MSn, and its anti-glycative properties were investigated using several
in vitro assays mimicking the different steps of the glycation reaction. In parallel, molecular
docking studies were carried out to evaluate potential interactions between the identified
metabolites and RAGE. Furthermore, A. citrodora metabolites’ stability under simulated
in vitro digestion was assessed, and the anti-glycative activity of the bioaccessible fraction
was investigated. Results: A. citrodora extract, rich in iridoid glycosides, phenylethanoid
glycosides, and flavones, strongly inhibited AGE formation (from 10% to 100%) in both
the middle and end step of the reaction and had high methylglyoxal and glyoxal trapping
capacity. However, the digestion process affected extract stability, particularly under
intestinal conditions, yielding an overall bioaccessibility of about 40% and leading to a
subsequent reduction in anti-glycative properties. Finally, molecular modeling analysis
highlighted the ability of the studied metabolites to bind RAGE. Conclusions: A. citrodora
represents a promising source of natural anti-glycative agents with potential applications
as food ingredients. However, it is essential to improve the extract bioaccessibility and to
preserve its anti-glycative properties by developing a suitable formulatio
An urban biorefinery for food waste and biological sludge conversion into polyhydroxyalkanoates and biogas
Full text linkThis study focuses on the application of the concept of circular economy, with the creation of added-value marketable products and energy from organic waste while minimizing environmental impacts. Within this purpose, an urban biorefinery technology chain has been developed at pilot scale in the territorial context of the Treviso municipality (northeast Italy) for the production of biopolymers (polyhydroxyalkanoates, PHAs) and biogas from waste of urban origin. The piloting system (100–380 L) comprised the following units: a) acidogenic fermentation of the organic fraction of municipal solid waste (OFMSW) and biological sludge; b) two solid/liquid separation steps consisting of a coaxial centrifuge and a tubular membrane (0.2 μm porosity); c) a Sequencing Batch Reactor (SBR) for aerobic PHA-storing biomass production; d) aerobic fed-batch PHA accumulation reactor and e) Anaerobic co-digestion (ACoD). The thermal pre-treatment (72 °C, 48 h) of the feedstock enhanced the solubilization of the organic matter, which was converted into volatile fatty acids (VFAs) in batch mode under mesophilic fermentation conditions (37 °C). The VFA content increased up to 30 ± 3 g COD/L (overall yield 0.65 ± 0.04 g CODVFA/g VS(0)), with high CODVFA/CODSOL (0.86 ± 0.05). The high CODVFA/CODSOL ratio enhanced the PHA-storing biomass selection in the SBR by limiting the growth of the non-storing microbial population. Under fully aerobic feast-famine regime, the selection reactor was continuously operated for 6 months at an average organic loading rate (OLR) of 4.4 ± 0.6 g COD/L d and hydraulic retention time (HRT) of 1 day (equal to SRT). The ACoD process (HRT 15 days, OLR 3.0–3.5 kg VS/m3 d) allowed to recover the residual solid-rich overflows generated by the two solid/liquid separation units with the production of biogas (SGP 0.44–0.51 m3/kg VS) and digestate. An overall yield of 7.6% wt PHA/VS(0) has been estimated from the mass balance. In addition, a preliminary insight into potential social acceptance and barriers regarding organic waste-derived products was obtained
Environmental assessment of the production of bio-plastics from urban bio-waste
No full textThe organic solid waste and sewage sludge management has important consequences on the overall environmental and economic performance of urban waste management systems. The RESURBIS is a Horizon 2020 project that proposes a biorefinery concept for the combined treatment of all the bio-waste produced in an urban area, mainly focusing on the production of polyhydroxyalkanoate (PHA). The objective of this study is to compare the global warming potential of the the business as usual (where organic solid waste is incinerated and sewage sludge is treated in an anaerobic digester and then incinerated) and the RESURBIS bio-refinery, using a consequential Life Cycle Assessment approach. The preliminary results show that the actual treatment of 1,000 kg of the considered bio-waste in the Great Copenhagen area causes 18 kg CO2-eq, while in the RESURBIS bio-refinery reduces this environmental burden to 8 kg CO2-eq. These preliminary results need to be confirmed by a more detailed environmental modelling
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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