Sviluppo di gasificatore e reattore di tar-cracking per l'utilizzo energetico di biomasse

La presente tesi di laurea ha per argomento l’utilizzo energetico della biomassa, con particolare riferimento alla tecnica di conversione termochimica di gassificazione. Il processo di gassificazione è, infatti, tuttora ampiamente in fase di studio, sia da un punto di vista di processo, che da un punto di vista di depurazione della corrente di gas di sintesi prodotta. La tesi è divisibile sostanzialmente in due parti: una prima parte bibliografica, in cui si fa ricerca di base sulle principali proprietà di interesse per le tecniche di conversione termochimica della biomassa, e una seconda parte progettuale/sperimentale, che ha per argomento il processo di gassificazione, mediante la progettazione di un reattore su scala da laboratorio, e gli interventi di purificazione della corrente di syngas dal tar (miscela di composti organici ossigenati) a valle della fase di reazione. Il Capitolo 2 contiene una raccolta di dati di letteratura relativi alle principali proprietà fisiche, chimiche e termiche delle biomasse, la conoscenza delle quali è di fondamentale importanza per l’individuazione dei possibili problemi derivanti dall’accoppiamento fra biocombustibile e tecnologia; si pone particolare attenzione sulle proprietà chimiche, descrivendo le metodologie di caratterizzazione della composizione chimica e di individuazione delle frazioni di cellulosa, emicellulosa, lignina; individuano infine i pretrattamenti a cui la biomassa viene solitamente sottoposta per il raggiungimento di caratteristiche ottimali per l’impiego energetico. Nel capitolo 3, dopo aver descritto il processo di gassificazione, si riporta un’analisi di letteratura relativa al funzionamento di gassificatori da laboratorio o su scala pilota e alle tecniche di rimozione del tar dal syngas mediante cracking termico o catalitico. Il Capitolo 4 è relativo alla progettazione di un gassificatore di biomassa su scala di laboratorio operante in pressione, ideato al fine di studiare gli effetti delle condizioni operative (temperatura, pressione, composizione alimentazione, tempo di residenza) sul processo. Il Capitolo 5 infine riporta i risultati dello studio sperimentale di rimozione del tar dal syngas. La fase di purificazione dal tar, caratteristica del processo di gassificazione, è stata studiata su un impianto di cracking termico esistente

Opening and closure forces of sliding mechanisms of different self-ligating brackets

Self-ligating brackets engage the wire by means of a slide mechanism. Forces that have to be applied to open and close the sliding mechanism of brackets are still unknown. Objective The aim of this study was to measure and compare the opening and closure forces of different self-ligating brackets. Material and Methods Three different stainless steel self-ligating brackets (Carriere LX, Ortho Organizers; F1000, Leone; Damon Q, Ormco) were tested. For each different bracket, 20 maxillary right central incisors and 20 mandibular right central incisors were used. Opening and closure forces were measured using an Instron Universal Testing Machine. Statistical analysis was performed and ANOVA and Tukey tests were carried out. Results Opening forces were registered between 1.1 N and 5.6 N, whereas closure forces were recorded between 1.57 N and 4.87 N. Significant differences were detected among the different brackets and between the two prescriptions tested. Conclusion The knowledge of different opening and closure forces of self-ligating brackets can help the orthodontist in the clinical management of these devices

Structure of the lectin mannose 6-phosphate receptor homology (MRH) domain of glucosidase II an enzyme that regulates glycoprotein folding quality control in the endoplasmic reticulum

Here we report for the first time the three-dimensional structure of a mannose 6-phosphate receptor homology (MRH) domain present in a protein with enzymatic activity, glucosidase II (GII). GII is involved in glycoprotein folding in the endoplasmic reticulum. GII removes the two innermost glucose residues from the Glc3Man9GlcNAc2 transferred to nascent proteins and the glucose added by UDP-Glc:glycoprotein glucosyltransferase. GII is composed of a catalytic GIIα subunit and a regulatory GIIβ subunit. GIIβ participates in the endoplasmic reticulum localization of GIIα and mediates in vivo enhancement of N-glycan trimming by GII through its C-terminal MRH domain. We determined the structure of a functional GIIβ MRH domain by NMR spectroscopy. It adopts a β-barrel fold similar to that of other MRH domains, but its binding pocket is the most shallow known to date as it accommodates a single mannose residue. In addition, we identified a conserved residue outside the binding pocket (Trp-409) present in GIIβ but not in other MRHs that influences GII glucose trimming activity.Fil: Olson, Linda J.. Medical College Of Wisconsin; Estados UnidosFil: Orsi, Ramiro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Alculumbre, Solana G.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Peterson, Francis C.. Medical College Of Wisconsin; Estados UnidosFil: Stigliano, Ivan Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Parodi, Armando Jose A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: D'alessio, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Universidad de Buenos Aires; ArgentinaFil: Dahms, Nancy M.. Medical College Of Wisconsin; Estados Unido

Massively parallel tag sequencing reveals the complexity of anaerobic marine protistan communities

© 2009 The Authors. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in BMC Biology 7 (2009): 72, doi:10.1186/1741-7007-7-72.Recent advances in sequencing strategies make possible unprecedented depth and scale of sampling for molecular detection of microbial diversity. Two major paradigm-shifting discoveries include the detection of bacterial diversity that is one to two orders of magnitude greater than previous estimates, and the discovery of an exciting 'rare biosphere' of molecular signatures ('species') of poorly understood ecological significance. We applied a high-throughput parallel tag sequencing (454 sequencing) protocol adopted for eukaryotes to investigate protistan community complexity in two contrasting anoxic marine ecosystems (Framvaren Fjord, Norway; Cariaco deep-sea basin, Venezuela). Both sampling sites have previously been scrutinized for protistan diversity by traditional clone library construction and Sanger sequencing. By comparing these clone library data with 454 amplicon library data, we assess the efficiency of high-throughput tag sequencing strategies. We here present a novel, highly conservative bioinformatic analysis pipeline for the processing of large tag sequence data sets.The analyses of ca. 250,000 sequence reads revealed that the number of detected Operational Taxonomic Units (OTUs) far exceeded previous richness estimates from the same sites based on clone libraries and Sanger sequencing. More than 90% of this diversity was represented by OTUs with less than 10 sequence tags. We detected a substantial number of taxonomic groups like Apusozoa, Chrysomerophytes, Centroheliozoa, Eustigmatophytes, hyphochytriomycetes, Ichthyosporea, Oikomonads, Phaeothamniophytes, and rhodophytes which remained undetected by previous clone library-based diversity surveys of the sampling sites. The most important innovations in our newly developed bioinformatics pipeline employ (i) BLASTN with query parameters adjusted for highly variable domains and a complete database of public ribosomal RNA (rRNA) gene sequences for taxonomic assignments of tags; (ii) a clustering of tags at k differences (Levenshtein distance) with a newly developed algorithm enabling very fast OTU clustering for large tag sequence data sets; and (iii) a novel parsing procedure to combine the data from individual analyses. Our data highlight the magnitude of the under-sampled 'protistan gap' in the eukaryotic tree of life. This study illustrates that our current understanding of the ecological complexity of protist communities, and of the global species richness and genome diversity of protists, is severely limited. Even though 454 pyrosequencing is not a panacea, it allows for more comprehensive insights into the diversity of protistan communities, and combined with appropriate statistical tools, enables improved ecological interpretations of the data and projections of global diversity.The International Census of Marine Microbes and the W.M. Keck Foundation award to the Marine Biological Laboratory at Woods Hole (MA) supported the pyrosequencing part of this study. Further financial support came from a grant from the Deutsche Forschungsgemeinschaft to TS (STO414/3-1). Support for the unpublished work on Cariaco Basin protists came from NSF MCB-0348407 to VE (collaborative project with S Epstein at Northeastern University, Boston, MA, USA). Financial support to AC was provided by NSF MCB-0348045. Financial support to RC was provided by the ANR-Biodiversité project Aquaparadox

Religion as practices of attachment and materiality: the making of Buddhism in contemporary London

This article aims to explore Buddhism’s often-overlooked presence on London’s urban landscape, showing how its quietness and subtlety of approach has allowed the faith to grow largely beneath the radar. It argues that Buddhism makes claims to urban space in much the same way as it produces its faith, being as much about the practices performed and the spaces where they are enacted as it is about faith or beliefs. The research across a number of Buddhist sites in London reveals that number of people declaring themselves as Buddhists has indeed risen in recent years, following the rise of other non-traditional religions in the UK; however, this research suggests that Buddhism differs from these in several ways. Drawing on Baumann’s (2002) distinction between traditionalist and modernist approaches to Buddhism, our research reveals a growth in each of these. Nevertheless, Buddhism remains largely invisible in the urban and suburban landscape of London, adapting buildings that are already in place, with little material impact on the built environment, and has thus been less subject to contestation than other religious movements and traditions. This research contributes to a growing literature which foregrounds the importance of religion in making contemporary urban and social worlds

Albiglutide and cardiovascular outcomes in patients with type 2 diabetes and cardiovascular disease (Harmony Outcomes): a double-blind, randomised placebo-controlled trial

Background: Glucagon-like peptide 1 receptor agonists differ in chemical structure, duration of action, and in their effects on clinical outcomes. The cardiovascular effects of once-weekly albiglutide in type 2 diabetes are unknown. We aimed to determine the safety and efficacy of albiglutide in preventing cardiovascular death, myocardial infarction, or stroke. Methods: We did a double-blind, randomised, placebo-controlled trial in 610 sites across 28 countries. We randomly assigned patients aged 40 years and older with type 2 diabetes and cardiovascular disease (at a 1:1 ratio) to groups that either received a subcutaneous injection of albiglutide (30–50 mg, based on glycaemic response and tolerability) or of a matched volume of placebo once a week, in addition to their standard care. Investigators used an interactive voice or web response system to obtain treatment assignment, and patients and all study investigators were masked to their treatment allocation. We hypothesised that albiglutide would be non-inferior to placebo for the primary outcome of the first occurrence of cardiovascular death, myocardial infarction, or stroke, which was assessed in the intention-to-treat population. If non-inferiority was confirmed by an upper limit of the 95% CI for a hazard ratio of less than 1·30, closed testing for superiority was prespecified. This study is registered with ClinicalTrials.gov, number NCT02465515. Findings: Patients were screened between July 1, 2015, and Nov 24, 2016. 10 793 patients were screened and 9463 participants were enrolled and randomly assigned to groups: 4731 patients were assigned to receive albiglutide and 4732 patients to receive placebo. On Nov 8, 2017, it was determined that 611 primary endpoints and a median follow-up of at least 1·5 years had accrued, and participants returned for a final visit and discontinuation from study treatment; the last patient visit was on March 12, 2018. These 9463 patients, the intention-to-treat population, were evaluated for a median duration of 1·6 years and were assessed for the primary outcome. The primary composite outcome occurred in 338 (7%) of 4731 patients at an incidence rate of 4·6 events per 100 person-years in the albiglutide group and in 428 (9%) of 4732 patients at an incidence rate of 5·9 events per 100 person-years in the placebo group (hazard ratio 0·78, 95% CI 0·68–0·90), which indicated that albiglutide was superior to placebo (p<0·0001 for non-inferiority; p=0·0006 for superiority). The incidence of acute pancreatitis (ten patients in the albiglutide group and seven patients in the placebo group), pancreatic cancer (six patients in the albiglutide group and five patients in the placebo group), medullary thyroid carcinoma (zero patients in both groups), and other serious adverse events did not differ between the two groups. There were three (<1%) deaths in the placebo group that were assessed by investigators, who were masked to study drug assignment, to be treatment-related and two (<1%) deaths in the albiglutide group. Interpretation: In patients with type 2 diabetes and cardiovascular disease, albiglutide was superior to placebo with respect to major adverse cardiovascular events. Evidence-based glucagon-like peptide 1 receptor agonists should therefore be considered as part of a comprehensive strategy to reduce the risk of cardiovascular events in patients with type 2 diabetes. Funding: GlaxoSmithKline

Dati sperimentali e conferme cliniche sulla biomeccanica a bassa frizione

Scopo del presente studio in vitro è stato quello di confrontare le forze frizionanti generate da un attacco autolegante (SmartClip, 3M Unitek) e da un attacco convenzionale (Step, Leone S.p.A.), in cui l’ingaggio dell’arco è stato realizzato con due legature diverse (elastiche convenzionali e Slide Leone), nell’ambito di un modello sperimentale per l’analisi dell’attrito generato da meccaniche di scorrimento. Gli attacchi sono stati fatti scorrere su due fili diversi, l’uno in acciaio inossidabile e l’altro in nichel-titanio, rispettivamente .019”X.025” e .014” di diametro. La resistenza allo scorrimento del sistema filo/attacco/legatura è stata valutata su un modello sperimentale applicato sul cursore mobile della macchina di trazione Instron con cella di carico da 10 N ed ognuno dei campioni è stato testato per dieci volte consecutive, sia all’asciutto che al bagnato. Si sono riscontrati livelli di forze frizionanti prossimi allo zero in tutti i casi in cui sul filo ortodontico è stato fatto scorrere l’attacco SmartClip oppure l’attacco convenzionale con legatura Slide, indipendentemente dal tipo di filo e dalle condizioni ambientali. La resistenza allo scorrimento aumenta invece in modo statisticamente significativo (p < 0,05) quando vengono impiegate le legature convenzionali. I risultati dei test suggeriscono pertanto che, in conseguenza della diminuzione dell’attrito, il sistema autolegante e la legatura low-friction Slide si caratterizzano per un’efficienza maggiore in quanto permettono che la quantità di forza applicata venga sfruttata quasi completamente per muovere il dente, producendo la stessa entità di scorrimento delle meccaniche convenzionali pur applicando una forza di intensità minore