Mix design and performance analysis of asphalt concretes with electric arc furnace slag

The paper presents the results of a laboratory study, aimed at verifying the possibility to use two particular typologies of electric arc furnace (EAF) steel slags, in substitution of the natural aggregates, in the composition of wearing course asphalt concrete for flexible pavements. The experimental research has been articulated in a preliminary study of the chemical, leaching, physical, and mechanical properties of the EAF steel slag, and in the following mix design and performance characterisation of the bituminous conglomerates, through gyratory compaction tests, permanent deformations tests, Stiffness Modulus tests at various temperatures, fatigue tests and indirect tensile strength tests. All the mixtures with EAF slag have satisfied the requisites for acceptance in the road sector technical standards, thus resulting as suitable for use in the construction of road infrastructures, moreover presenting higher mechanical characteristics than those of the corresponding asphalts with full natural aggregate.     

Post-cracking behaviour of steel and macro-synthetic fibre-reinforced concretes

The present paper describes the results of an experimental investigation on the performances of concrete specimens reinforced with either steel or macro-synthetic fibres under three-point bending. Steel fibres are often used to improve the flexural toughness of concrete and are used in various structural applications while synthetic fibres are more often used to reduce crack opening due to shrinkage. Macro-synthetic fibres have been proposed more recently with the aim of creating an alternative to steel fibres in structural applications but their use is still limited.In the tests performed, specimens cast with the same concrete mix, but containing different dosages of either steel or macro-synthetic fibres, were used and compared. In general steel fibres were more efficient in increasing the toughness of concrete than macro-synthetic fibres, even though their results were significantly more scattered.Test results were used to calculate the parameters of stress-crack opening relations via inverse analysis using a cracked hinge model. This numerical model provided results, in terms of force-Crack Mouth Opening Displacement (CMOD) curves, in very good agreement with the experimental data.     

Study of the adhesion of Staphylococcus aureus to coated glass substrates

The adhesion of Staphylococcus aureus was studied using a selection of laboratory-prepared and commercially available coated glass substrates using a simple methodology. Substrates were examined by scanning electron microscopy, atomic force microscopy and water droplet contact angles. It was found that microbial adhesion was independent of surface roughness, when this was of a lower magnitude than microbial size. It was also found that microbial adhesion was greater for hydrophilic surfaces than for hydrophobic ones, but that on a photoinduced superhydrophilic surface, microbes were more spread out—a potential benefit for more effective photocatalytic disinfection. It is suggested that hydrophobic and photoinduced superhydrophilic surface coatings both have potential as a means of reducing microbial fouling of surfaces.     

A mechatronic platform for human touch studies

The development of a mechatronic tactile stimulation platform for touch studies is presented. The platform was developed for stimulation of the fingertip using textured surfaces, providing repeatable tangential sliding motion of stimuli with controlled indentation force. Particular requirements were addressed to make the platform suitable for neurophysiological studies in humans with particular reference to electrophysiological measurements, but allowing a variety of other studies too, such as psychophysical, tribological and artificial touch ones. The design of the mechatronic tactile stimulator is detailed, as well as the performance in tracking reference trajectories. Using microneurography, we recorded from human tactile afferents and validated the platform compatibility with the exacting demands of electrophysiological methods, comprising the absence of spurious vibrations and the lack of relevant electromagnetic interference.     

Toward Stretchable Self‐Powered Sensors Based on the Thermoelectric Response of PEDOT:PSS/Polyurethane Blends

The development of new flexible and stretchable sensors addresses the demands of upcoming application fields like internet‐of‐things, soft robotics, and health/structure monitoring. However, finding a reliable and robust power source to operate these devices, particularly in off‐the‐grid, maintenance‐free applications, still poses a great challenge. The exploitation of ubiquitous temperature gradients, as the source of energy, can become a practical solution, since the recent discovery of the outstanding thermoelectric properties of a conductive polymer, poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS). Unfortunately the use of PEDOT:PSS is currently constrained by its brittleness and limited processability. Herein, PEDOT:PSS is blended with a commercial elastomeric polyurethane (Lycra), to obtain tough and processable self‐standing films. A remarkable strain‐at‐break of ≈700% is achieved for blends with 90 wt% Lycra, after ethylene glycol treatment, without affecting the Seebeck voltage. For the first time the viability of these novel blends as stretchable self‐powered sensors is demonstrated.     

A Multiphase Pore Scale Network Model of Gas Exchange in Apple Fruit

A multiphase pore scale network model was developed to describe mass transfer in apple fruit. The 3D microscale geometry of the tissue was reconstructed from synchrotron radiation tomography images. Individual cells and pores were identified using a watershed segmentation procedure on a Euclidean distance map of the tissue microstructure. Further morphological characteristics of each individual pore, including its volume, connections to the neighbors and the connected area between the pore and its neighbors, were determined. The tissue was represented by a network of nodes (simplified individual pores and cells) that were interconnected by tubes. The transport of the respiratory gases O₂ and CO₂ between two nodes was modelled using diffusion laws and irreversible thermodynamics, while respiration was taken into account in the individual cellular nodes. A numerical procedure was applied to simulate the gas transport within the discrete network and to compute the local diffusivities of the links in the network. The predicted overall gas diffusivities compared well to experimental data and results computed from a microscale continuum model, thereby validating the pore scale network model. This approach is a computationally attractive alternative to a continuum multiphase approach for modelling gas transport in fruit.     

Comparative structural and immunochemical properties of leghaemoglobins

Circular dichroism studies on leghaemoglobins from snake bean, lupin, serradella and other plants show that, in common with soybean (reported earlier) they have a similar overall polypeptide chain conformation and haem environment and orientation. Immunochemical studies, on the other hand, suggest that the antigenic determinants on the surface of the leghaemoglobins vary considerably. Thus, firstly the alpha-helix content of the leghaemoglobins as a class is very similar (60-65%) and approaches that of the myoglobins, secondly, the sign, magnitude and shape of their circular dichroism spectra in the near ultraviolet, Soret and visible regions suggest close similarities in the environment and orientation of a structurally important tryptophan residue and of the haem moiety, and thirdly, there is comparatively weak haem-protein interaction. The extent of immuno cross-reactivity was found to be best deomonstrated using the Farr radioimmunoassay procedure. The results were (a) 5 leghaemoglobins from one plant (soybean) crossreacted completely but with varying affinities. (b) The extent of cross reactivity between leghaemoglobins from different plants was compared to that within a single plant; the reaction of antiserum to a soybean leghaemoglobin with a serradella leghaemoglobin was weak, with a snake bean leghaemoglobin still weaker (and incomplete) while lupin leghaemoglobins showed no cross reactivity at all. (c) The "rapid" attenuation of cross reactivity among different plant leghaemoglobins is explicable in terms of the extensive amino acid substitutions which have been demonstrated in the literature and in the present studies. (d) In view of this rapid divergence it is not surprising that sperm whale and horse heart myoglobins showed no cross reactivity with soybean leghaemoglobins. In summary, amino acid substitutions in the leghaemoglobin family are conformationally but not immunochemically conservative.     

Comparison of bioactive phytochemical content and release of isothiocyanates in selected brassica sprouts

The consumption of brassica sprouts as raw vegetables provides a fair amount of glucosinolates (GLs) and active plant myrosinase, which enables the breakdown of GLs into health-promoting isothiocyanates (ITCs). This study reports the determination of the main constituents related to human health found in edible sprouts of two Brassica oleracea varieties, broccoli and Tuscan black kale, and two Raphanus sativus varieties, Daikon and Sango. Radish sprouts exhibited the highest ability to produce ITCs, with Daikon showing the greatest level of conversion of GLs into bioactive ITCs (96.5%), followed by Sango (90.0%). Tuscan black kale gave a value of 68.5%, whereas broccoli displayed the lowest with 18.7%. ITCs were not the exclusive GL breakdown products in the two B. oleracea varieties, since nitriles were also produced, thus accounting for the lower conversion observed. Measuring the release of plant ITCs is a valuable tool in predicting the potential level of exposure to these bioactive compounds after the consumption of raw brassica sprouts.