1,721,022 research outputs found
Methanol synthesis from renewable electrical energy: A feasibility study
No full textThis paper aims to present a feasibility study of an innovative plant for methanol synthesis from carbon dioxide and hydrogen, produced by water electrolyser fed by renewable electrical energy. The analysis aims to examine a methanol production plant, based on 1MW of installed electrolyser, from both the management and economic standpoints: the 1MW plant size has been chosen to represent a modular plant for the power to fuel distributed generation, which may be powered by renewable energy. The thermo-economic investigation is performed using two different approaches: a detailed design point analysis, carried out in order to identify the optimal component sizes and operating parameters followed by a time-dependent plant management optimization. Both the studies are carried out with two simulation tools, named WTEMP (Web-based Thermo-Economic Modular Program) and W-ECoMP (Web-based Economic Poly-generative Modular Program), both developed by the Thermochemical Power Group at University of Genoa
A comparative techno-economic and sensitivity analysis of Power-to-X processes from different energy sources
No full textIn this paper, green hydrogen produced via water electrolysis and its conversion into three alternative fuels, such as methane, methanol, and ammonia, are considered. The four different Power-to-Fuel solutions are investigated and compared from both the technical and economic points of view aiming at providing a comprehensive overview of the Power-to-Fuel feasibility. At first, the global process efficiency, the storage capacity, the annual costs, and the production cost of the different fuels (in terms of mass, energy, and hydrogen content) are calculated for a reference scenario. Then, a sensitivity analysis is carried out analyzing the influence of many parameters (i.e. electricity cost, electrolyser CAPEX, operating hours, etc) on the economic viability of all the processes. Finally, map plots are developed reporting the fuel production cost for considering different renewable energy sources and their availability. They can be considered as a useful tool for pre-feasibility analysis of power to fuel processes enabling to analyze and compare the different solutions in different scenarios. It is found that the highest efficient process is the Power-to-Hydrogen (about 61.5%) followed by the methanol and ammonia processes and in the end the methane processes. In terms of energy storage and energy density by volume, the methanol resulted in the most suitable solution, while the ammonia resulted in the best H2 storage medium in terms of kg of H2 per m3 of storage (108 kgH2/m3). From the economic perspective, the annual cost breakdown showed that, in all the cases, the major expenditures are related to the electrical energy purchase and CAPEX and OPEX of the electrolyzer (around 90% of total costs), and a 50% reduction in electricity cost and electrolyzer CAPEX could lead to a reduction of about 30% and 18% on fuel production cost, respectively. The cheapest fuel in terms of mass and energy content are methanol (1.02 €/kg) and Hydrogen (0.16€/kWh), respectively. The ammonia production cost in terms of hydrogen content in mass resulted almost comparable with the Hydrogen one (5.76€/kgH2 and 5.31€/€/kgH2, respectively). The contribution of the co-produced oxygen sale has been estimated in around a 15% reduction of fuel production cost in all the cases
Novel insights into the metal binding ability of ZinT periplasmic protein from Escherichia coli and Salmonella enterica
No full textThe ZinT mediated Zn(ii) uptake is one of the major differences in the metabolism of human and bacterial cells that can be challenged when looking for possible highly selective metal-based therapeutics. ZinT is a 216-amino acid periplasmic protein expressed by Gram-negative bacteria, which shuttles Zn(ii) ions to the ZnuABC transporter under zinc-limiting conditions. The suggested metal-binding sites of ZinT correspond to a domain containing three highly conserved histidine residues (His 167, 176 and 178) and to the N-terminal histidine-rich loop HGHHXH (residues 24-29). The coordination chemistry of the ZinT complexes with Zn(ii) and Cu(ii) has been investigated. The present work is focused on the protected peptides Ac-24HGHHSH29-NH2 and Ac-166DHIIAPRKSSHFH178-NH2 as models for the putative metal binding sites of ZinT from Escherichia coli (EcZinT), and Ac-24HGHHAH29-NH2 and Ac-166DHIIAPRKSAHFH178-NH2 from the ZinT protein expressed by Salmonella enterica sv. Typhimurium (SeZinT). The investigated peptides are able to form stable mono-nuclear complexes where the histidine residues represent the principal metal anchoring sites. The ZnuA (a periplasmic component of the ZnuABC transporter) metal binding site exhibits higher affinity for Zn(ii) than ZinT, suggesting that the interaction of the two proteins through the formation of a binary complex may involve the metal transfer from ZinT to ZnuA. In contrast, this would not occur in Cu(ii), since the ZinT complexes are more stable. Furthermore, at acidic pH, where the antimicrobial peptide calcitermin is biologically active, it also binds the metal ions with higher affinity than ZinT, representing a possible efficient competitor and antagonist of ZinT in the host human organism
Economic feasibility of methanol synthesis as a method for CO2 reduction and energy storage
No full textIn this paper, a thermo-economic analysis concerning a methanol production plant is performed. In particular, this study was developed with the aim of evaluating the opportunity and viability of obtaining methanol from the chemical reaction between recycled CO2, emitted from a fossil-fuel power station, and hydrogen produced by water electrolysis. This solution can represent an interesting carbon dioxide reduction method and methanol as a product can be considered an energy storage means. As a first step, a thermodynamic analysis is performed in order to determine the mass and energy flows of the plant; then, a feasibility analysis concerning a large size methanol production plant is performed taking into account three different economic scenarios (Germany, Italy, and China). In order to evaluate the economic viability, the total investment cost and payback period are calculated in all the scenarios. Different methanol and electrical energy prices are considered, to take into proper account the influence of these parameters on mid-term future scenarios. Moreover, a sensitivity analysis, considering different oxygen selling prices and PEM electrolyzer capital costs, were performed
Deferoxamine B: A Natural, Excellent and Versatile Metal Chelator
No full textDeferoxamine B is an outstanding molecule which has been widely studied in the past decade for its ability to bind iron and many other metal ions. The versatility of this metal chelator makes it suitable for a number of medicinal and analytical applications, from the well-known iron chelation therapy to the most recent use in sensor devices. The three bidentate hydroxamic functional groups of deferoxamine B are the centerpiece of its metal binding ability, which allows the formation of stable complexes with many transition, lanthanoid and actinoid metal ions. In addition to the ferric ion, in fact, more than 20 different metal complexes of deferoxamine b have been characterized in terms of their chemical speciation in solution. In addition, the availability of a terminal amino group, most often not involved in complexation, opens the way to deferoxamine B modification and functionalization. This review aims to collect and summarize the available data concerning the complex-formation equilibria in solutions of deferoxamine B with different metal ions. A general overview of the progress of its applications over the past decade is also discussed, including the treatment of iron overload-associated diseases, its clinical use against cancer and neurodegenerative disorders and its role as a diagnostic tool
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
A multi-criteria approach for comparing alternative fuels and energy systems onboard ships
No full textThis paper aims to present the upgrade of the Helper for Energy Layouts in Maritime applications (HELM) software tool, developed by the authors to compare traditional and innovative systems for energy production and storage onboard maritime vessels. The algorithm adopts a multi-criteria method and it carries out the analysis on a large and updated database of market solutions. A wide range of maps is implemented in the tool, correlating costs, volumes, weights, emissions and fuel environmental hazards with energy demand, applicative scenario and vessel type. The equations implemented in the software and the algorithm employed to evaluate and compare the technologies are reported. In this work, four different vessels are investigated, namely: (i) a small sail yacht; (ii) a small passenger ferry for inland water navigation; (iii) a large cruise ship; (iv) a large container ship. For each case study, the choice of the best solution is performed, considering the constraints, the inputs and the single parameters: in all cases, the solution chosen corresponds to the real one installed on board or to a solution that is going to be installed. It is worth noting that the multi-criteria analysis has a general approach, allowing to give preliminary information on the best energy system solution, also to comply with the application requirements (i.e. pollutant emissions in ports and restricted areas)
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