Ottimizzazione dello scambio termico nelle fasi di stiro e stabilizzazione del monofilamento in HDPE con forni ad acqua e ad aria​​

Nella produzione di monofilamenti in polietilene ad alta densità (HDPE), le fasi di stiro e stabilizzazione sono realizzate da forni con elevati consumi di energia termica e bassa efficienza. L’ottimizzazione dei processi può avvenire solo se vi è un’approfondita conoscenza dei fenomeni di trasmissione del calore tra fili e fluido circostante (aria o acqua). I coefficienti di scambio termico dipendono dalla distanza di separazione tra i filamenti che attraversano il forno, come dalla temperatura e dalla velocità relativa tra fili e fluido; le variazioni di questi parametri, se ben gestite nell’ambito di precisi range, consentono di agire efficacemente sulle dimensioni del forno e quindi sui consumi di energia termica. Le simulazioni termofluidodinamiche condotte prendono in esame due particolari modelli commerciali di forno, uno ad acqua e l’altro ad aria. I risultati ottenuti evidenziano che una distanza di 2,5 mm tra i fili permette di massimizzare il coefficiente di scambio termico convettivo, pari a circa 5000 W/(m2 K) nel caso dell’acqua e a circa 470 W/(m2 K) per l’aria. La potenza necessaria a realizzare i processi è pari a circa 47 kW nel caso della vasca ad acqua e di 17 kW in quello del forno ad aria. Si osserva, dunque, che, per i due modelli di forno esaminati, anche se le condizioni di scambio termico dell’acqua sono molto migliori rispetto all’aria, la possibilità di adottare temperature più elevate di quest’ultima permette una riduzione della potenza totale: il modello di forno ad aria è alimentabile con una potenza pari a circa il 36% di quella necessaria al modello di vasca ad acqua

City watchdog finds no evidence for recent political ‘debanking’ – but private banks have been picky for centuries

Disclosure statement: The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.After a row over the closure of his bank account earlier this year, former politician Nigel Farage has hit out at the UK financial regulator for saying it has found no recent evidence of customers being “de-banked” over their personal views

Polymeric foams 3D numerical mechanical modelling

One of the main open issues in the field of polymeric foam materials is the lack of a relationship between the foam geometrical characteristics and its constituent material properties, on one side, and the macroscopic mechanical behavior. This link is an essential ingredient for the development of a predictive numerical model able to fully describe the mechanical behavior of polymeric foams under different loading conditions, which is the ultimate goal of the present work. In order to build up a systematic and methodological approach to this problem, polymeric structural closed cell foams having different nominal densities (ranging from 60 to 120 kg/m3) were considered. The internal foam structure was investigated throughout micro-Computed Tomography; the acquired stack of images were processed with a home-made algorithm in which Mean Intercept Length method was implemented to compute material volume distribution and the degree of structural anisotropy. The algorithm also allowed the reconstruction of the real geometry using a voxel-based scheme, to perform Finite Element Analysis. With the aim of reducing geometric discontinuities, inherent in the reconstructed voxel mesh, Taubin’s smoothing algorithm was employed to obtain more accurate results. Numerical simulations mimicking experimental quasi-static uniaxial compression test were performed to obtain nominal stress vs. strain curves. To this purpose, suitable mechanical properties were identified for the (equivalent solid) constituent material: the resulting constitutive law highlights the contribution of the material to the macroscopic foam properties. Relevant mechanical parameters such as elastic moduli, buckling strain and plateau stress were then evaluated and related to geometrical features of the real foam

Year-round variation in the isotopic niche of Scopoli's shearwater (Calonectris diomedea) breeding in contrasting sea regions of the Mediterranean Sea

Top marine predators are key components of marine food webs. Among them, long-distance migratory seabirds, which travel across different marine ecosystems over the year, may experience important year-round changes in terms of oceanographic conditions and availability of trophic resources. We tested whether this was the case in the Scopoli's shearwater (Calonectris diomedea), a trans-equatorial migrant and top predator, by sampling birds breeding in three environmentally different regions of the Mediterranean Sea. The analysis of positional data and stable isotopes (δ1³C and δ15N) of target feathers revealed that birds from the three regions were spatially segregated during the breeding period while they shared non-breeding areas in the Atlantic Ocean. Isotopic baseline levels of N and C (meso-zooplankton) were significantly different among marine regions during breeding. Such variation was reflected at the higher trophic levels of pelagic and demersal fish muscles as well as in shearwater feathers grown in the Mediterranean. δ15N- and δ13C-adjusted values of shearwaters were significantly different among populations suggesting that birds from different breeding areas relied on prey species from different trophic levels. Conversely, the non-breeding spatial and isotopic niches overlapped greatly among the three populations. Shearwater trophic niches during breeding were narrower and segregated compared to the non-breeding period, revealing a high plasticity in trophic resource use. Overall, this study highlights seasonal and region-specific use of trophic resources by Scopoli's shearwater, suggesting a broad trophic plasticity and possibly a high adaptability to environmental changes

Postpartum women’s psychological experiences during the COVID-19 pandemic: a modified recurrent cross-sectional thematic analysis

Background: COVID-19 has placed additional stressors on mothers during an already vulnerable lifecourse transition. Initial social distancing restrictions (Timepoint 1; T1) and initial changes to those social distancing restrictions (Timepoint 2; T2) have disrupted postpartum access to practical and emotional support. This qualitative study explores the postpartum psychological experiences of UK women during different phases of the COVID-19 pandemic and associated ‘lockdowns’. Methods: Semi-structured interviews were conducted with 12 women, approximately 30 days after initial social distancing guidelines were imposed in the UK (22 April 2020). A separate 12 women were interviewed approximately 30 days after the initial easing of social distancing restrictions (10 June 2020). Data were transcribed verbatim, uploaded into NVivo for management and analysis, which followed a recurrent cross-sectional approach to thematic analysis. Results: Two main themes were identified for T1: ‘Motherhood is Much Like Lockdown’ and ‘A Self-Contained Family Unit’. Each main T1 theme contained two sub-themes. Two main themes were also identified for T2: ‘Incongruously Held Views of COVID-19’ and ‘Mothering Amidst the Pandemic’. Each main T2 theme contained three sub-themes. Comparisons between data gathered at each timepoint identified increased emotional distress over time. Current findings call for the improvement of postpartum care by improving accessibility to social support, and prioritising the re-opening of schools, and face-to-face healthcare appointments and visitation. Conclusion: Social distancing restrictions associated with COVID-19 have had a cumulative, negative effect on postpartum mental health. Recommendations such as: Allowing mothers to ‘bubble’ with a primary support provider even at their healthcare appointments; allowing one support partner to attend all necessary healthcare appointments; and providing tailored informational resources, may help to support postpartum emotional wellbeing during this, and similar health crises in the future

Interindividual variation and consistency of migratory behavior in the Eurasian woodcock

Diverse spatio-temporal aspects of avian migration rely on relatively rigid endogenous programs. However, flexibility in migratory behavior may allow effective coping with unpredictable variation in ecological conditions that can occur during migration. We aimed at characterizing inter- and intraindividual variation of migratory behavior in a forest-dwelling wader species, the Eurasian woodcock Scolopax rusticola, focusing on spatio-temporal consistency across repeated migration episodes. By satellite-tracking birds from their wintering sites along the Italian peninsula to their breeding areas, we disclosed a remarkable variability in migration distances, with some birds flying more than 6,000 km to Central Asian breeding grounds (up to 101\ub0E). Prebreeding migration was faster and of shorter duration than postbreeding migration. Birds moving over longer distances migrated faster during prebreeding migration, and those breeding at northernmost latitudes left their wintering areas earlier. Moreover, birds making longer migrations departed earlier from their breeding sites. Breeding site fidelity was very high, whereas fidelity to wintering areas increased with age. Migration routes were significantly consistent, both among repeated migration episodes and between pre- and postbreeding migration. Prebreeding migration departure date was not significantly repeatable, whereas arrival date to the breeding areas was highly repeatable. Hence, interindividual variation in migratory behavior of woodcocks was mostly explained by the location of the breeding areas, and spatial consistency was relatively large through the entire annual cycle. Flexibility in prebreeding migration departure date may suggest that environmental effects have a larger influence on temporal than on spatial aspects of migratory behavior

Eliciting imitation in early infancy

N/

Sex categorization of faces: The effects of age and experience

The face own-age bias effect refers to the better ability to recognize the face from one's own age compared with other age groups. Here we examined whether an own-age advantage occurs for faces sex categorization. We examined 7- and 9-year-olds' and adults' ability to correctly categorize the sex of 7- and 9-year-olds and adult faces without external cues, such as hair. Results indicated that all ages easily classify the sex of adult faces. They succeeded in classifying the sex of child faces, but their performance was poorer than for adult faces. In adults, processing time increased, and a response bias (male response) was elicited for child faces. In children, response times remained constant, and no bias was observed. Experience with specific category of faces seems to offer some advantage in speed of processing. Overall, sex categorization is more challenging for child than for adult faces due to their reduced sexual dimorphic facial characteristics

In vivo and in vitro immune responses against Francisella tularensis vaccines are comparable among Fischer 344 rat substrains

Identifying suitable animal models and standardizing preclinical methods are important for the generation, characterization, and development of new vaccines, including those against Francisella tularensis. Non-human primates represent an important animal model to evaluate tularemia vaccine efficacy, and the use of correlates of vaccine-induced protection may facilitate bridging immune responses from non-human primates to people. However, among small animals, Fischer 344 rats represent a valuable resource for initial studies to evaluate immune responses, to identify correlates of protection, and to screen novel vaccines. In this study, we performed a comparative analysis of three Fischer rat substrains to determine potential differences in immune responses, to evaluate methods used to quantify potential correlates of protection, and to evaluate protection after vaccination. To this end, we took advantage of data previously generated using one of the rat substrains by evaluating two live vaccines, LVS and F. tularensis SchuS4-ΔclpB (ΔclpB). We compared immune responses after primary vaccination, adaptive immune responses upon re-stimulation of leukocytes in vitro, and sensitivity to aerosol challenge. Despite some detectable differences, the results highlight the similarity of immune responses to tularemia vaccines and challenge outcomes between the three substrains, indicating that all offer acceptable and comparable approaches as animal models to study Francisella infection and immunity