1,720,999 research outputs found
Diesel Fuel by Scrap-Tyre Thermal-Mechanical Pyrolysis
No full textCurrent energy policies are encouraging the near-term use of
fuels derived from civil and industrial waste residues, giving
new perspectives for their disposal.
The possibility of using, in Diesel engines, a liquid fuel
derived from waste synthetic polymeric matrices, such as
scrap tyres, is evaluated in this paper. The fuel is obtained
by means of an innovative technology based on a thermomechanical
cracking process at moderate temperatures and
pressures.
A preliminary investigation was carried out on a 440 cm3
single-cylinder Diesel engine for stationary employ using
plain automotive Diesel fuel and two mixtures of
automotive Diesel fuel and tyre pyrolysis oil (TPO): the first
one containing 20% TPO by volume, the other containing
40% TPO. With the first mixture, test bench results in terms
of engine torque, power, specific fuel consumption and
exhaust emissions are similar to the ones relative to plain
automotive Diesel fuel, whereas the use of the mixture with
40% TPO leads to a general worsening in engine
combustion features.
Lubricant oil analysis, performed at the end of the tests,
shows a certain level of contamination, however without any
abnormal decay of lubricant properties.
The toxicity levels of the exhaust particulate matter were
analysed and result to be the same using plain automotive
Diesel fuel and both the mixtures of Diesel fuel and TPO.
No meaningful mechanical inconvenience occurred during
the engine tests. Nevertheless, long-time reliability of the
injection system, as well as of the entire engine, has to be
verified
Pyrolyzed tannery sludge as adsorbent of volatile organic compounds from tannery air emissions
No full textThe tanning industry has a great impact on the environment for the large consumption of water, the huge amount of waste generated, and the high emissions of volatile organic compounds (VOCs), used in leather finishing operations. In this study, pyrolyzed tannery sludge (PTS) was investigated, after further pyrolysis at high temperature, as a sorbent of VOCs. Pyrolysis experiments were performed at various temperatures (750–850 °C) and times (6–60 min) to evaluate the optimal operating conditions in terms of developed BET specific surface area. Fixed bed adsorption experiments were performed to determine the breakthrough curves at room temperature using an air stream containing n-butyl acetate, a VOC largely used in leather finishing products. By pyrolysis at 850 °C for 6 min the BET of PTS increased from 72 to 127 m2/g, improving its sorption capacity. The effects of superficial velocity, inlet VOC concentration, and bed height on the sorption behaviour of PTS after further pyrolysis (PPTS) were investigated. Breakthrough curves were well fitted by the Bohart-Adams model (R2 = 0.92) and the adsorption isotherms with Freundlich equation (R2 = 0.97). Preliminary sorbent desorption tests were carried out by hot air in the temperature range 100–180 °C, demonstrating the feasibility of thermally regenerating this material. Multiple adsorption/desorption cycles on the PPTS will be performed on lab scale in a future study to investigate the real sorbent recyclability
Extraction of polyhydroxyalkanoates from purple non-sulfur bacteria by non-chlorinated solvents
Full text linkIn this study, non-chlorinated solvents such as cyclohexanone (CYC) and three ionic liq-uids, (ILs) (1-ethyl-3-methylimidazolium dimethylphosphate, [EMIM][DMP], 1-ethyl-3-methylim-idazolium diethylphosphate, [EMIM][DEP] and 1-ethyl-3-methylimidazolium methylphosphite, [EMIM][MP]) were tested to extract polyhydroxyalkanoates (PHAs) from the purple non-sulfur photosynthetic bacterium (PNSB) Rhodovulum sulfidophilum DSM-1374. The photosynthetic bacterium was cultured in a new generation photobioreactor with 4 L of working volume using a lactate-rich medium. The extracted PHAs were characterized using a thermogravimetric analysis, differential scanning calorimetry, infrared spectroscopy, proton nuclear magnetic resonance and gel perme-ation chromatography. The most promising results were obtained with CYC at 125 °C with an extraction time of above 10 min, obtaining extraction yields higher than 95% and a highly pure poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-HV) with around 2.7 mol% of hydroxylvalerate (HV). A similar yield and purity were obtained with chloroform (CHL) at 10 °C for 24 h, which was used as the referent solvent Although the three investigated ILs at 60 °C for 4 and 24 h with bio-mass/IL up to 1/30 (w/w) obtained PHAs strongly contaminated by cellular membrane residues, they were not completely solubilized by the investigated ILs
Thermoplastic Blends Based on Poly(Butylene Succinate-co-Adipate) and Different Collagen Hydrolysates from Tanning Industry: I—Processing and Thermo-mechanical Properties
Full text linkIn this study, blends of a biodegradable thermoplastic polyester, poly (butylene succinate-co-adipate) (PBSA) with two different raw hydrolyzed collagens (HCs), derived from the tannery industry, were investigated in terms of processability, rheological, thermal and mechanical properties. HCs, obtained by alkaline (HCa) and enzymatic (HCe) hydrolysis of the solid wastes generated during the shaving of the tanned leather, were used in PBSA/HC blends, up to 20 wt% of HC, produced by melting extrusion and processed by injection molding. All the blends up to 20 wt% HCs resulted suitable for the injection molding obtaining flexible molded specimens with good tensile properties. The different secondary structure of the two HCs influenced the rheology, morphology and mechanical properties of the produced blends. In particular, HCa, due its higher content of oligopeptides and free amino-acids, showed a good compatibility with the polymeric matrix acting as a plasticizer with consequent reduction of melt viscosity with increasing its loading. The molded dog-bones specimens containing 20 wt% HCa showed a value of elongation at break of 810%. While, HCe, due its higher presence of b-sheet structures, behaved as organic filler, showing a poor interfacial interaction with PBSA with consequent decrease of the tensile properties with increasing its loading. The good processability and satisfactory mechanical properties obtained encourage the use of both investigated collagen hydrolysates in the production of thermoplastic blends and relative molded products for applications in agriculture and plant nurseries, such as pots or small containers with fertilizing properties, due the presence of HCs
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
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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