Development and Validation of a CFD Combustion Model for Natural Gas Engines Operating with Different Piston Bowls

Nowadays, an accurate and precise description of the combustion phase is essential in spark-ignition (SI) engines to drastically reduce pollutant and greenhouse gas (GHG) emissions and increase thermal efficiency. To this end, computational fluid dynamics (CFD) can be used to study the different phenomena involved, such as the ignition of the charge, combustion development, and pollutant formation. In this work, a validation of a CFD methodology based on the flame area model (FAM) was carried out to model the combustion process in light-duty SI engines fueled with natural gas. A simplified spherical kernel approach was used to model the ignition phase, whereas turbulent flame propagation was described through two variables. A zero-dimensional evolution of the flame kernel radius was used in combination with the Herweg and Maly formulation to take the laminar-to-turbulent flame transition into account. To estimate the chemical composition of burnt gas, two different approaches were considered—one was based on tabulated kinetics, and the other was based on chemical equilibrium. Assessment of the combustion model was first performed by using different operating points of a light-duty SI engine fueled with natural gas and by using the original piston. The results were validated by using experimental data on the in-cylinder pressure, apparent heat release rate, and pollutant emissions. Afterward, two other different piston bowl geometries were investigated to study the main differences between one solution and the others. The results showed that no important improvements in terms of combustion efficiency were obtained by using the new piston bowl shapes, which was mainly due to the very low ((Formula presented.)) or null increase in turbulent kinetic energy during the compression stroke and due to the higher heat losses ((Formula presented.)) associated with the increased surface area of the new piston geometries

Exercise respiratory cycle time components in patients with emphysema

Background: We have recently demonstrated that in patients with COPD the severity of emphysema (E) measured by high resolution computed tomography (HRCT) correlated with: ratio VTpeak/FEV1; VE/VCO2 slope and PETCO2 values at peak exercise. The aim of this study was to further investigate if exercise respiratory cycle time components correlated with % of E measured by HRCT. Method: Twelve patients (age = 65±8 yrs; FEV1 = 55±17%pred) with moderate to severe E (quantified by lung HRCT as % voxels < −910 HU) were evaluated with incremental cardiopulmonary exercise testing (CPET). Mean inspiratory time (TiM), mean total respiratory cycle time (TtotM), mean expiratory time during exercise (TeM) and mean expiratory time during the last third of exercise (TeM-end), has been calculated. Results: Both TeM and TeM-end had a good linear correlation with % of E (r = 0,61; p = 0,004 and r = 0,63; p = 0,003). Moreover, by dividing the patients in two groups based on the % of E (>50% and <50%), we observed that patients with higher % of E had longer TeM (TeM: 1,72±0,26sec vs 1,34±0,27sec, p = 0,005) and TeM-end. A good linear correlation has been observed also between TeM and PETCO2 and VE/VCO2 (r = 0,64; p = 0,002 and r = 0,7; p = 0,0005). TeM did not correlated with resting lung function values or inspiratory capacity (IC). Conclusion: The data confirm that distinct physiologic response pattern can be detected at CPET in these patients

Modeling an ontology on accessible evacuation routes for emergencies

Providing alert communication in emergency situations is vital to reduce the number of victims. However, this is a challenging goal for researchers and professionals due to the diverse pool of prospective users, e.g. people with disabilities as well as other vulnerable groups. Moreover, in the event of an emergency situation, many people could become vulnerable because of exceptional circumstances such as stress, an unknown environment or even visual impairment (e.g. fire causing smoke). Within this scope, a crucial activity is to notify affected people about safe places and available evacuation routes. In order to address this need, we propose to extend an ontology, called SEMA4A (Simple EMergency Alert 4 [for] All), developed in a previous work for managing knowledge about accessibility guidelines, emergency situations and communication technologies. In this paper, we introduce a semi-automatic technique for knowledge acquisition and modeling on accessible evacuation routes. We introduce a use case to show applications of the ontology and conclude with an evaluation involving several experts in evacuation procedures. © 2014 Elsevier Ltd. All rights reserved

Numerical assessment of integrated thermal management systems in electrified powertrains

Temperatures in internal combustion engines (ICE) impact fuel consumption and pollutant emissions, especially under transient operating conditions. In hybrid powertrains, where the reciprocating internal combustion engine has intermittent operating conditions, a optimum control of these temperatures is critical. In this work, a detailed methodology for studying integrated thermal management systems for hybrid propulsion system was presented. Both experimental measurements and 0D/1D models were implemented and validated for the different components of the hybrid vehicle powertrain. The novelty of this work consists in the extensive experimental measurements involved for the development of the different models, specially the ICE, in order to study the integration of the different thermal flows of a hybrid powertrain. Furthermore, the simulation methodology used in this work integrates different modelling tools and takes advantage of their strengths when compared to using a single modelling tool. Two different thermal management systems have been evaluated under different Real Driving Emission (RDE) cycles at two different temperatures (at 20 °C and -20 °C). Results have shown that during the ICE warming up, the integrated thermal management system improved energy consumption by 1.74% and 3% for warm and cold conditions, respectively. This was because, the integrated TMS allows to avoid the temperature drop of the ICE when the propulsive system is in pure electric mode. © 2022 Elsevier Lt

Italy-Japan agreement and discrepancies in diagnosis of superficial gastric lesions.

The agreement between Italian and Japanese endoscopists and pathologists on endoscopic and histopathological diagnoses of superficial gastric lesions is verified with the use of Paris and Vienna classifications. The correlations between Paris endoscopic types and Vienna histopathological categories is high in both the independent Italian and Japanese evaluations. However, the agreement between Italian and Japanese endoscopists is moderate due to the difficult evaluation of the height of the lesions, in particular when they are mixed. The agreement on the size of the lesions is fairly good. The probability of the same allocation to the Vienna categories of a single case is 87 per cent, disagreements remaining in dysplasia grading, between dysplasia, not only high-grade but also low-grade, and in situ carcinoma, and on cancer invasion of the lamina propria. The results indicate that use of the Paris and Vienna classifications has reduced the discrepancies between Western and Japanese endoscopists and pathologists in the diagnosis of these lesions

Zika virus induces FOXG1 nuclear displacement and downregulation in human neural progenitors

Congenital alterations in the levels of the transcription factor Forkhead box g1 (FOXG1) coding gene trigger "FOXG1 syndrome," a spectrum that recapitulates birth defects found in the "congenital Zika syndrome," such as microcephaly and other neurodevelopmental conditions. Here, we report that Zika virus (ZIKV) infection alters FOXG1 nuclear localization and causes its downregulation, thus impairing expression of genes involved in cell replication and apoptosis in several cell models, including human neural progenitor cells. Growth factors, such as EGF and FGF2, and Thr271 residue located in FOXG1 AKT domain, take part in the nuclear displacement and apoptosis protection, respectively. Finally, by progressive deletion of FOXG1 sequence, we identify the C-terminus and the residues 428-481 as critical domains. Collectively, our data suggest a causal mechanism by which ZIKV affects FOXG1, its target genes, cell cycle progression, and survival of human neural progenitors, thus contributing to microcephaly

The ISWI Chromatin Remodeler Organizes the hsrω ncRNA–Containing Omega Speckle Nuclear Compartments

The complexity in composition and function of the eukaryotic nucleus is achieved through its organization in specialized nuclear compartments. The Drosophila chromatin remodeling ATPase ISWI plays evolutionarily conserved roles in chromatin organization. Interestingly, ISWI genetically interacts with the hsrω gene, encoding multiple non-coding RNAs (ncRNA) essential, among other functions, for the assembly and organization of the omega speckles. The nucleoplasmic omega speckles play important functions in RNA metabolism, in normal and stressed cells, by regulating availability of hnRNPs and some other RNA processing proteins. Chromatin remodelers, as well as nuclear speckles and their associated ncRNAs, are emerging as important components of gene regulatory networks, although their functional connections have remained poorly defined. Here we provide multiple lines of evidence showing that the hsrω ncRNA interacts in vivo and in vitro with ISWI, regulating its ATPase activity. Remarkably, we found that the organization of nucleoplasmic omega speckles depends on ISWI function. Our findings highlight a novel role for chromatin remodelers in organization of nucleoplasmic compartments, providing the first example of interaction between an ATP-dependent chromatin remodeler and a large ncRNA

Chemical Composition of PM10 at Urban Sites in Naples (Italy)

Here, we report the chemical characterization and identification of the possible sources of particulate matter (fraction PM10) at two different sites in Naples. PM10 concentration and its chemicalcompositionwerestudiedusingthecrustalenrichmentfactor(EF)andprincipalcomponent analysis (PCA). In all of the seasons, the PM10 levels, were significantly higher (p 0.8) was obtained between reconstructed mass and gravimetric mass. PCA analysis explained 76% and 79% of the variance in NA01 and NA02, respectively. The emission sources were the same for both sites; but, the location of the site, the different distances from the sources and the presence and absence of vegetation proved the different concentrations and compositions of PM10

Pedicled and skeletonized single and bilateral internal thoracic artery grafts and the incidence of sternal wound complications: Insights from the Arterial Revascularization Trial

Objectives: The question of whether skeletonized internal thoracic artery harvesting reduces the incidence of sternal wound complications in comparison with the pedicled technique, in the context of single or bilateral internal thoracic arteries, remains controversial. We studied the impact of the internal thoracic artery harvesting strategy on sternal wound complication in the Arterial Revascularization Trial. Methods: Patients enrolled in the Arterial Revascularization Trial (n = 3102) were randomized to coronary artery bypass grafting with single or bilateral internal thoracic arteries. Sternal wound complication rates were examined according to the harvesting technique that was documented in 2056 patients. The internal thoracic artery harvesting technique, based on the surgeon's preference, resulted in 4 groups: pedicled single internal thoracic artery (n = 607), pedicled bilateral internal thoracic artery (n = 459), skeletonized single internal thoracic artery (n = 512), and skeletonized bilateral internal thoracic artery (n = 478). Propensity scores weighting was used to estimate the impact of the harvesting technique on sternal wound complications. Results: A total of 219 of 2056 patients (10.6%) experienced a sternal wound complication within 1 year from the index operation. Of those, only 25 patients (1.2%) required sternal wound reconstruction. Pedicled bilateral internal thoracic artery (odds ratio [OR], 1.80; 95% confidence interval [CI], 1.23-2.63) but not skeletonized bilateral internal thoracic artery (OR, 1.00; 95% CI, 0.65-1.53) or skeletonized single internal thoracic artery (OR, 0.89; 95% CI, 0.57-1.38) was associated with a significantly increased risk of any sternal wound complications compared with pedicled single internal thoracic artery. Conclusions: The present Arterial Revascularization Trial substudy suggests that, with a skeletonization technique, the risk of sternal wound complication with bilateral internal thoracic artery grafting is similar to that after standard pedicled single internal thoracic artery harvesting, whereas skeletonized single internal thoracic artery harvesting did not add any further benefit when compared with pedicled single internal thoracic artery harvesting