Nonsimple isotropic incompressible linear fluids surrounding one-dimensional structures

We introduce a model of fluid which has four main features: it readily emerges by a general continuum mechanical framework; it is a generalization maintaining most of the physical features of incompressible Newtonian fluids; it can model adherence interactions with one-dimensional structures surrounded by the fluid; the associated initial boundary-value problem is well-posed on three-dimensional domains.     

The contribution of attention in virtual moped riding training of teenagers

Riding a moped, like many other everyday activities, is a complex behavior in which attention plays a crucial role. This study aims to investigate the role of attention in enhancing the skills required to ride a moped simulator. Two experiments were conducted with 207 and 60 students (14–15 years old), respectively, using a moped simulator to ride on 12 different tracks. The assignment was to ride safely and avoid hazards. In experiment 1, we divided the hazard scenes of the tracks on the basis of the fact that a shift in attention was required to escape the danger. We showed that during the riding training, when no attentional shift was required, the ability to avoid hazards was constantly higher. In experiment 2, participants were asked to cope with the same basic experimental setting but with an additional attentive task. The results showed that they performed in such a way that not only did the attentive task not impair their performance, but it also produced an improvement in the ability to shift attentional focus, preserving performance efficiency. On the basis of these data, it can be claimed that, primarily, attentional shift plays a prominent role in accounting for accident circumstances. Secondarily, it can be claimed that attentional training contributes to improved processing efficiency so as to prevent mishaps.     

In-service performance assessment of electrostatic precipitators serving a rubber vulcanization process

We examined two emission abatement systems of some vulcanization ovens, serving a unit producing small rubber-based parts for automotive application. Each emission control unit treats the gases exhausted by three to five ovens. A heat exchanger cools down the fumes to a temperature suitable for the correct operation of a couple of two-stage electrostatic precipitators in series. We performed quantitative analysis of concentrations and size distributions in these rubber fumes using aerosol technology instrumentation, namely optical particle spectrometers and electrical mobility particle sizers. The size of sampled particles was mainly between 100?nm and 1000?nm. We evaluated the performance of the exhaust fume abatement units, with focus on the electrostatic precipitator. Concerning batch ovens, the quantitative trend of the emissions follows the thermal cycle of the post-curing process. Time interval since the last maintenance operation causes a gradual reduction in the removal efficiency. The measured data demonstrate the reliability and the adequacy of aerosol instrumentation for the characterization of the emissions from rubber vulcanization ovens. The pair of electrostatic precipitators was shown to be effective in removing most of the particles detected in the fumes stream. The measurement protocol developed in this study allows assessing the influence of the maintenance schedule on the performance of the emission control units. New technologies for treating organic vapors can be evaluated in a reliable and effective way.

Copyright © 2019 American Association for Aerosol Research     

Magnetic resonance butterfly coils: Design and application for hyperpolarized C studies

Hyperpolarized ¹³C magnetic resonance spectroscopy in pig models enables cardiac metabolism assessment and provides a powerful tool for heart physiology studies, although the low molar concentration of derivate metabolites gives rise to technological limitations in terms of data quality. The design of dedicated coils capable of providing large field of view with high Signal-to-Noise Ratio (SNR) data is of fundamental importance.     

Effect of various alumina nano‐fillers on the thermal and mechanical behaviour of low‐density polyethylene–Al2O3 composites

Two different alumina powders were dispersed in low‐density polyethylene (LDPE) to evaluate if any role can be ascribed to the crystalline phase, size and morphology of the alumina filler. In particular a submicrometric α‐alumina and a nanocrystalline transition (γ/δ) alumina were added to the polymer at 5 wt% concentration, using a Brabender mixing unit. Both the neat inorganic fillers showed a good dispersibility in the polyolefin. The thermal and mechanical properties of the composites obtained were evaluated. As expected, a significant increase of the stiffness and abrasion resistance of LDPE was achieved in both cases. Furthermore, the composites showed a higher thermo‐oxidative stability with respect to neat LDPE. Independent of their crystalline phase, size and morphology, both fillers gave a similar enhancement of composite features. Copyright © 2010 Society of Chemical Industry     

The role of spatial agglomeration in a structural model of innovation,productivity and export: a firm-level analysis

In this article, using a large sample of Italian manufacturing firms, we estimate a structural model of research, innovation, productivity and export performance augmented to take account for the role played by spatial agglomeration externalities. This model, which is an ‘augmented’ version of Crépon et al. (Econ Innov New Technol 7(2):115–158, 1998) model, comprises five main equations. The first two identify the factors underlying the decision and intensity of Research and Development (R&D) investments; the third links R&D capital to innovation output; the fourth focuses on Total Factor Productivity (TFP) as determined by innovation; the fifth relates TFP to export performance. Our estimates show the significant role played by local externalities in these processes. In particular, related variety and urbanization positively affect the creation of new ideas through R&D, while specialization impacts on TFP to complement innovation output. Finally, urbanization economies support TFP in driving firms’ export performance.     

Charge Photogeneration in Few‐Layer MoS2

The 2D semiconductor MoS₂ in its mono‐ and few‐layer form is expected to have a significant exciton binding energy of several 100 meV, suggesting excitons as the primary photoexcited species. Nevertheless, even single layers show a strong photovoltaic effect and work as the active material in high sensitivity photodetectors, thus indicating efficient charge carrier photogeneration. Here, modulation spectroscopy in the sub‐ps and ms time scales is used to study the photoexcitation dynamics in few‐layer MoS₂. The results suggest that the primary photoexcitations are excitons that efficiently dissociate into charges with a characteristic time of 700 fs. Based on these findings, simple suggestions for the design of efficient MoS₂ photovoltaic and photodetector devices are made.     

Comparative measurements of highly irradiated n-in-p and p-in-n 3D silicon strip detectors

Silicon detectors in 3D technology are a candidate for applications in environments requiring an extreme radiation hardness, as in the innermost layers of the detectors at the proposed High-Luminosity LHC. In 3D detectors, the electrodes are made of columns etched into the silicon perpendicular to the surface. This leads to higher electric fields, a smaller depletion voltage and a reduced trapping probability of the charge carriers compared to standard planar detectors. In this article, the signal and the noise of irradiated n-in-p and p-in-n 3D silicon strip detectors are compared. The devices under test have been irradiated up to a fluence of 2×10¹⁶ 1 MeV neutron equivalent particles per square centimetre (n_eq/cm²), which corresponds to the fluence expected for the inner pixel detector layers at the High-Luminosity LHC. A relative charge collection efficiency of approximately 70% was obtained even after the highest irradiation fluence with both detector types. The influence of different temperatures on the signal and the noise is investigated and results of annealing measurements are reported.     

Modeling the decay of ammonium oxidizing bacteria

A bench-scale sequencing batch reactor was used to study factors affecting the endogenous decay of the ammonium oxidizing biomass (AOB) in different operating conditions. AOB decay was very sensitive to oxygen concentration, and increased up to 0.4 d⁻¹ for oxygen concentration of 7 mg O₂ L⁻¹. The decay in anaerobic conditions was shown to be very low (0.03 d⁻¹) when compared to literature data.The effect of nitrite and nitrate on AOB decay was also studied. The correlation was quite weak suggesting that both nitrate and nitrite absence had little impact on decay which is contrary to what is typically assumed in some of the existing process models. A simple expression for the decay of AOB was proposed, calibrated and validated using the results of batch kinetic tests and of the continuous sequencing batch reactor monitoring.