Condensation in a square minichannel: application of the VOF method

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.A number of steady-state simulations of condensation of R134a at mass fluxes G=100 kg m-2s-1 and G=800 kg m-2s-1 inside a square cross section minichannel (Dh=1mm) are here proposed and compared against similar simulations in a circular cross section channel with same diameter. The VOF (Volume Of Fluid) method is used to track the vapour-liquid interface and the effects of interfacial shear stress and surface tension are both taken into account. A uniform wall temperature is fixed as boundary condition. At G=100 kg m-2s-1 the liquid film is assumed laminar and the vapour flow is turbulent; turbulence is handled by a low-Reynolds number form of the standard k-w model (Wilcox, 1998), which was modified in order to suppress the turbulent viscosity inside the liquid phase. At G=800 kg m-2s-1 a low Re form of the SST k-w model (Menter, 1994) has been used for turbulence modeling through both the liquid and vapour phases. Numerical simulations are validated against experimental data. The present paper looks at the effect of surface tension. Its influence on the shape of the vapour-liquid interface provides some heat transfer enhancement in non-circular minichannels. In circular minichannels, the overall effect of surface tension is shown to be not significant. On the contrary, the effect of surface tension in square channels provides a large enhancement at low mass flux

Microbial assisted phytodepuration for water reclamation: Environmental benefits and threats

Climate changes push for water reuse as a priority to counteract water scarcity and minimize water footprint especially in agriculture, one of the highest water consuming human activities. Phytodepuration is indicated as a promising technology for water reclamation, also in the light of its economic and ecological sustainability, and the use of specific bacterial inocula for microbial assisted phytodepuration has been proposed as a further advance for its implementation. Here we provided an overview on the selection and use of plant growth promoting bacteria in Constructed Wetland (CW) systems, showing their advantages in terms of plant growth support and pollutant degradation abilities. Moreover, CWs are also proposed for the removal of emerging organic pollutants like antibiotics from urban wastewaters. We focused on this issue, still debated in the literature, revealing the necessity to deepen the knowledge on the antibiotic resistance spread into the environment in relation to treated wastewater release and reuse. In addition, given the presence in the plant system of microhabitats (e.g. rhizosphere) that are hot spot for Horizontal Gene Transfer, we highlighted the importance of gene exchange to understand if these events can promote the diffusion of antibiotic resistance genes and antibiotic resistant bacteria, possibly entering in the food production chain when treated wastewater is used for irrigation. Ideally, this new knowledge will lead to improve the design of phytodepuration systems to maximize the quality and safety of the treated effluents in compliance with the 'One Health' concept

Development and calibration of a structural simulation method of CF-SMC composite parts processed by compression molding

The need for the reduction in CO2 production in automotive field increasingly leads manufacturers to consider fiber-reinforced composite materials that are however costly to processes. Discontinuous fiber composite materials, like CF – SMC, are a competitive candidate because they are transformed by the high productivity compression molding technology. On the negative side, their structural complexity introduces high variability in the mechanical performance that needs to be considered at the design stage. This contribution describes the development of a structural modeling strategy for parts made of CF-SMC processed by compression molding. It is based the statistical material model proposed by Feraboli implemented here in a FEA-based structural analysis procedure. After validation and calibration of a specific CF-SMC material, the proposed procedure is applied to the simulation of the structural response of a compression molded part of complex geometry subjected to know loading condition

Fatigue behaviour of thin Fe-Si steel sheets for electric motor production

The on-going evolution toward electric/hybrid traction requires the development of high-performance electric motors. The rotor of electric motors is made from a stack of thin steel sheets and a complex configuration of magnets. Electric steels are typically Fe-Si alloys where Si addition controls grain size. Mechanical durability assessment of electric motors is based on the fatigue performance of Fe-Si steels. This contribution reports a thorough mechanical characterisation of a Fe-Si alloy in the form of thin (i.e. 0.2 mm) sheets. Numerous tensile tests were performed to characterize the reference static properties and their respective scatter. A suitable fatigue testing procedure for thin sheets was developed and used in an extensive campaign aimed at investigating the directional fatigue behaviour of the Fe-Si steel. Comparison with literature data confirms that the fatigue response of thin sheets is affected by different factors related especially to the method of extraction

Losing Parasocial Friendships over Celebrity Politics: A Cognitive Discrepancies Approach

The present study examines 4 cognitive discrepancy management strategies that media users can use in response to a celebrity making a political statement that runs contrary to their beliefs. The experiment (N = 382) replicates the results using 3 celebrities and 2 attitude object contexts. Exposure to a celebrity making political statements that the media user disagrees with resulted in weaker parasocial relationships with the celebrity and attribution of lesser importance to that issue. Viewers who particularly liked the celebrity prior to the study were more likely to decouple the actor from their line of work to continue enjoying the actor’s media content despite their political disagreement. These findings illuminate the potential consequences of celebrity politics for both the media figures’ stardom and the citizens’ political participation. (PsycInfo Database Record (c) 2022 APA, all rights reserved) Impact Statement Entertainment celebrities often voice their stance on various social issues. The study examines the consequences of this practice, showing that although entertainers can leverage their celebrity status to attenuate public opinion, it might come at the cost of their popularity. These findings can inform efforts to maximize the impact of political advocacy, enhance celebrity management practices, and promote political participation

Individual-based Markov model of virus diffusion: Comparison with COVID-19 incubation period, serial interval and regional time series

A Markov chain individual-based model for virus diffusion is investigated. Both the virus growth within an individual and the complexity of the contagion within a population are taken into account. A careful work of parameter choice is performed. The model captures very well the statistical variability of quantities like the incubation period, the serial interval and the time series of infected people in Tuscany towns

Polysaccharide Layer-by-Layer Coating for Polyimide-Based Neural Interfaces

Implantable flexible neural interfaces (IfNIs) are capable of directly modulating signals of the central and peripheral nervous system by stimulating or recording the action potential. Despite outstanding results in acute experiments on animals and humans, their long-term biocompatibility is hampered by the effects of foreign body reactions that worsen electrical performance and cause tissue damage. We report on the fabrication of a polysaccharide nanostructured thin film as a coating of polyimide (PI)-based IfNIs. The layer-by-layer technique was used to coat the PI surface due to its versatility and ease of manufacturing. Two different LbL deposition techniques were tested and compared: dip coating and spin coating. Morphological and physiochemical characterization showed the presence of a very smooth and nanostructured thin film coating on the PI surface that remarkably enhanced surface hydrophilicity with respect to the bare PI surface for both the deposition techniques. However, spin coating offered more control over the fabrication properties, with the possibility to tune the coating’s physiochemical and morphological properties. Overall, the proposed coating strategies allowed the deposition of a biocompatible nanostructured film onto the PI surface and could represent a valid tool to enhance long-term IfNI biocompatibility by improving tissue/electrode integration

Landscape and Environmental Impact Evaluation of Roundabouts

The interest of researchers and practitioners on roundabout solutions has been growing increasingly in the last decades. The often large areas occupied by this type of intersections require special attention on the use of ground and the preservation of the natural, environmental and architectural heritage. This aim also presents the opportunity for evaluating their impact on the landscape and environment. The paper proposes a new method developed for roundabout evaluation (but generalizable to other infrastructures and fields) borrowed from building technology and based on the needs, requirements and performance expected from an object rather than on prescriptions for and descriptions of its dimensions and quality. Applications on two roundabouts are presented in order to highlight practical developments. Their final evaluation sheets are presented and through them it is relatively easy to single out the problems and drawbacks of the roundabouts from the landscape point of view

Postseismic deformation and body forces shaping the Apennines and adjacent sedimentary basins in Umbria-Marche

The geodynamic complexity of the Apennines and adjacent sedimentary basins in Umbria-Marche (North-Central Italy) makes the dynamics of the present day deformation and its relationships with the seismicity less well understood. In this paper, we argue that, further to buoyancy forces, postseismic deformation of earthquakes taking place on the Apennines contributes to the regional deformation. We investigate the interaction between the normal faulting system responsible of the 1997 Umbria-Marche earthquake sequence (Colfiorito fault) and the low angle normal faulting system bordering the sedimentary basins, namely the Altotiberina fault. We set-up a 2D finite element model of the lithosphere-asthenosphere accounting for lateral heterogeneities and investigate how this heterogeneous structure is capable of localizing strain under the Umbria-Marche sedimentary basins, providing a way for the Colfiorito fault to influence the evolution of the Altotiberina fault. We show how the two different length and time scale processes, namely postseismic deformation and buoyancy, are complementary in shaping the Apennines and adjacent sedimentary basins. The high resolution deformation patterns modeled in this study can hardly be reproduced by a model accounting only for external forces such as a rotating or subducting or retreating Adria

Impact of IFN lambda 3/4 single nucleotide polymorphisms on the cytomegalovirus reactivation in autologous stem cell transplant patients

Cytomegalovirus (CMV) infection represents one of the main cause mortality after Stem Cell Transplantation. Recently, a protective effect of the T allele of rs12979860 IL28B Single Nucleotide Polymorphisms (SNPs) against CMV infection in the allogenic stem cell transplantation was suggested. We investigate whether the rs12979860 IL28B SNP and the relative rs368234815 (IFNλ4) genotype may affect the incidence of active CMV infection in Autologous stem cell transplantation (Auto-SCT) setting. The study included 99 patients who underwent to Auto-SCT. IL28 and IFNΔ4 SNPs were correlated with CMV reactivation along with other clinical and treatment parameters. CMV reactivation by CMV DNAemia was evaluated once a week until day 100 from Auto-SCT. CMV reactivation was documented in 50% (TT-ΔG/ΔG), 35% (CC-TT/TT) and 29.2% (CT-TT/ΔG) of the patients respectively. No differences in CMV copies number were recorded at reactivation between different IL28/IFNλ4 genotypes. The analysis of patients older than 60 years showed a significantly higher incidence of active CMV infection in the TT-ΔG/ΔG (83%) population with respect to CC-TT/TT (21%) and CT-TT/ΔG (40%) patients. Our data suggest a negative role of TT-ΔG/ΔG genotype in the CMV reactivation in Auto-SCT. The exposure to rituximab and the pre-infusion presence of anti CMV IgG also significantly influenced CMV reactivation