196,126 research outputs found
A logical characterization of coherence for imprecise probabilities
No full textWhilst supported by compelling arguments, the representation of uncertainty by means of (subjective) probability does not enjoy a unanimous consensus. A substantial part of the relevant criticisms point to its alleged inadequacy for representing ignorance as opposed to uncertainty. The purpose of this paper is to show how a strong justification for taking belief as probability, namely the Dutch Book argument, can be extended naturally so as to provide a logical characterization of coherence for imprecise probability, a framework which is widely believed to accommodate some fundamental features of reasoning under ignorance. The appropriate logic for our purposes is an algebraizable logic whose equivalent algebraic semantics is a variety of MV-algebras with an additional internal unary operation representing upper probability (these algebras will be called UMV-algebras)
A logical characterization of coherence for imprecise probabilities
No full textAbstractWhilst supported by compelling arguments, the representation of uncertainty by means of (subjective) probability does not enjoy a unanimous consensus. A substantial part of the relevant criticisms point to its alleged inadequacy for representing ignorance as opposed to uncertainty. The purpose of this paper is to show how a strong justification for taking belief as probability, namely the Dutch Book argument, can be extended naturally so as to provide a logical characterization of coherence for imprecise probability, a framework which is widely believed to accommodate some fundamental features of reasoning under ignorance. The appropriate logic for our purposes is an algebraizable logic whose equivalent algebraic semantics is a variety of MV-algebras with an additional internal unary operation representing upper probability (these algebras will be called UMV-algebras)
Effect of nitrogen plasma treatment on the crystallinity and self‐bonding of polyetheretherketone (PEEK) for biomedical applications
No full textPolyetheretherketone (PEEK) is a thermoplastic material with outstanding properties and high potential for biomedical applications, including hermetic encapsulation of active implantable devices. Different biomedical grade PEEK films with initial degree of crystallinity ranging from 8% to 32% (with or without mineral filling) were inspected. PEEK surfaces were treated with nitrogen RF plasma and the effects on materials crystallinity and self‐bonding were evaluated. In particular, the relationship between auto‐adhesive properties and crystalline content of PEEK before and after plasma treatment was examined.
PEEK samples showed different bonding strength depending on their degree of crystallinity, with higher self‐bonding performance of mineral‐filled semi‐crystalline films. XRD did not show any modification of the PEEK microstructure as a result of plasma treatment, excluding a significant influence of crystallinity on the self‐bonding mechanisms. Nevertheless, plasma surface treatment successfully improved the self‐bonding strength of all the PEEK films tested, with larger increase in the case of semi‐crystalline unfilled materials. This could be interpreted to the increase in chain mobility that led to interfacial interpenetration of the amorphous phase
Preparation of ultra violet - cured nanocomposite coatings for protecting against corrosion of metal substrates
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Gold Nanoparticles: Role of Size and Surface Chemistry on Blood Proteins Adsorption
No full textMaterial interaction with blood proteins is a critical issue, since it could influence the biological processes taking place in the body following implantation/injection. This is particularly important in the case of nanoparticles, where innovative properties, such as size and high surface to volume ratio can lead to a behavioral change with respect to bulk macroscopic materials and could be responsible for a potential risk for human health. The aim of this work was to compare gold nanoparticles (AuNP) and planar surfaces to study the role of surface curvature moving from the macro- to the nano-size in the process of blood protein adsorption. In the course of the study, different protocols were tested to optimize the analysis of protein adsorption on gold nanoparticles. AuNP with different size (10, 60 and 200 nm diameter) and surface coatings (citrate and polyethylene glycol) were carefully characterized. The stabilizing action of blood proteins adsorbed on AuNP was studied measuring the variation of size and solubility of the nanoparticles following incubation with single protein solutions (human serum albumin and fibrinogen) and whole blood plasma. In addition, we developed a method to elute proteins from AuNP to study the propensity of gold materials to adsorb plasma proteins in function of dimensional characteristics and surface chemistry. We showed a different efficacy of the various eluting media tested, proving that even the most aggressive agent cannot provide a complete detachment of the protein corona. Enhanced protein adsorption was evidenced on AuNP if compared to gold laminae (bare and PEGylated) used as macroscopic control, probably due to the superior AuNP surface reactivity
Integrated electrochemical approach for the investigation of silane pre-treatments for painting copper
No full textCopper surfaces are sometimes protected with an organic coating to improve the durability or the aesthetic properties. Examples of industrial applications are household appliances and heat exchanger components.
In order to extend the service life of the organic coated copper a specific surface pre-treatment is often required. Nevertheless, probably because of the limited market of this application, no specific pre-treatments for copper are industrially developed, with the exception of cleaning procedures, but simply extensions of existing pre-treatments optimised for other metals (aluminium, zinc, magnesium alloys) are used.
The application of silane pre-treatments as adhesion promoters for organic coated metals is remarkably increasing in the last decade, because silanes offer very good performance together with high environmental compatibility.
The idea is therefore to try to develop a specific silane based pre-treatment for copper. The starting point is the existing silane products for aluminium, modifying the composition and the application conditions (concentration, pH of the bath, additives, etc.) in order to develop a high performance copper alloy pretreatment increasing the protective properties and the adhesion of a successively applied organic coating.
The deposits were analysed using FT-IR spectroscopy and optical and electron microscopic observations.
A electrochemical characterization was carried out to highlight the silane properties and to evaluate the performance of the different deposits.
A final powder coating was applied and the properties of the complete protecting cycle was evaluated.
The electrochemical approach is based mainly on electrochemical impedance spectroscopy measurement
Iron-glycine precipitation-free electrolyte for aqueous redox flow batteries
No full textIron-based redox flow batteries are cheap, safe, flexible stationary energy storage devices that can alleviate the demand for critical raw materials in Europe. However, several challenges persist in the development of iron-based electrolytes matching operational requirements, among which is hydrolysis-induced precipitation of iron compounds in mild acidity conditions. In this work, we address the problem of iron precipitation by the addition of glycine into an iron-based aqueous electrolyte. To verify and optimize the electrolyte properties for battery applications, the study addresses the very concentrated conditions typically used in an industrially relevant cell, namely 1 M FeCl2, 1 M FeCl3, and glycine ranging from 0 to 4 M. On these electrolytes, ionic conductivity, dynamic viscosity, and pH are measured and electrochemical characterization is performed through cyclic voltammetry scans with an RDE in a three-electrode cell. Given glycine's feature to suppress redox couple reactivity, the exchange current density was determined employing Koutecký-Levich analysis, particularly suited due to the electrolyte's sluggish kinetic, indicative of a quasi-reversible system. The study shows how the precipitation of insoluble iron hydroxides is strongly suppressed with 1 M glycine while preserving much of the attractive characteristics of the original iron chemistry. A maximum of 120 mS/cm of ionic conductivity is reached at concentrations corresponding to 50 % SoC without supporting electrolyte and with a slight increase in viscosity up to 3 mPa s. The exchange current density ranges from 4 to 10 mA/cm2, with an open circuit potential of 0.54 V vs. Ag/AgCl sat. at 90 % SoC, making this system an attractive catholyte for a high-energy density iron-based RFB
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