Coefficient of thermal expansion of nanostructured tungsten based coatings assessed by thermally induced substrate curvature method

The in plane coefficient of thermal expansion (CTE) and the residual stress of nanostructured W based coatings are extensively investigated. The CTE and the residual stresses are derived by means of an optimized ad-hoc developed experimental setup based on the detection of the substrate curvature by a laser system. The nanostructured coatings are deposited by Pulsed Laser Deposition. Thanks to its versatility, nanocrystalline W metallic coatings, ultra-nano-crystalline pure W and W-Tantalum coatings and amorphous-like W coatings are obtained. The correlation between the nanostructure, the residual stress and the CTE of the coatings are thus elucidated. We find that all the samples show a compressive state of stress that decreases as the structure goes from columnar nanocrystalline to amorphous-like. The CTE of all the coatings is higher than the one of the corresponding bulk W form. In particular, as the grain size shrinks, the CTE increases from 5.1 10$^{-6}$ K$^{-1}$ for nanocrystalline W to 6.6 10$^{-6}$ K$^{-1}$ in the ultra-nano-crystalline region. When dealing with amorphous W, the further increase of the CTE is attributed to a higher porosity degree of the samples. The CTE trend is also investigated as function of materials stiffness. In this case, as W coatings become softer, the easier they thermally expand.Comment: The research leading to these results has also received funding from the European Research Council Consolidator Grant ENSURE (ERC-2014-CoG No. 647554

Translocation pathways for inhaled asbestos fibers

We discuss the translocation of inhaled asbestos fibers based on pulmonary and pleuro-pulmonary interstitial fluid dynamics. Fibers can pass the alveolar barrier and reach the lung interstitium via the paracellular route down a mass water flow due to combined osmotic (active Na+ absorption) and hydraulic (interstitial pressure is subatmospheric) pressure gradient. Fibers can be dragged from the lung interstitium by pulmonary lymph flow (primary translocation) wherefrom they can reach the blood stream and subsequently distribute to the whole body (secondary translocation). Primary translocation across the visceral pleura and towards pulmonary capillaries may also occur if the asbestos-induced lung inflammation increases pulmonary interstitial pressure so as to reverse the trans-mesothelial and trans-endothelial pressure gradients. Secondary translocation to the pleural space may occur via the physiological route of pleural fluid formation across the parietal pleura; fibers accumulation in parietal pleura stomata (black spots) reflects the role of parietal lymphatics in draining pleural fluid. Asbestos fibers are found in all organs of subjects either occupationally exposed or not exposed to asbestos. Fibers concentration correlates with specific conditions of interstitial fluid dynamics, in line with the notion that in all organs microvascular filtration occurs from capillaries to the extravascular spaces. Concentration is high in the kidney (reflecting high perfusion pressure and flow) and in the liver (reflecting high microvascular permeability) while it is relatively low in the brain (due to low permeability of blood-brain barrier). Ultrafine fibers (length < 5 μm, diameter < 0.25 μm) can travel larger distances due to low steric hindrance (in mesothelioma about 90% of fibers are ultrafine). Fibers translocation is a slow process developing over decades of life: it is aided by high biopersistence, by inflammation-induced increase in permeability, by low steric hindrance and by fibers motion pattern at low Reynolds numbers; it is hindered by fibrosis that increases interstitial flow resistances

YY CMi: contact or near contact system?

New V photoelectric observations of the eclipsing system YY CMi, obtained at La Silla, Chile, and Merate Observatory, Italy, are presented. New times of minima and ephemeris based on our observations are also given. The V light curve was analysed by using the WD code to derive the geometrical and physical parameters of the system. Since no spectroscopic mass ratio is available, the q-search method was applied to yield the preliminary range of the mass ratio in order to search for the final solution. First the unspotted solution was carried out by using the unperturbed parts of the light curve and applying the DC program of the WD code. The solution was performed by assuming contact (mode 3) and semi-detached (mode 4) configuration, since no classification of the system is possible from the shape of the light curve. The solution in mode 4 does not lead to an acceptable model, since the secondary was found to be slightly overcontact. Therefore the contact solution was finally adopted. Moreover the light curve peculiarities (Max II fainter than Max I and excess of light around the phase 0.32) were explained by assuming a cool and a hot spot on the surface of the secondary (cooler) component. The degree of contact is very small (f about 3%) and the thermal contactis poor (T1-T2) about 650 K. These results together with the high photometric mass ratio q about 0.89 indicate that YY CMi is very probably a system at the beginning or the end of the contact phase.Comment: 7 pages, 7 ps figures. Accepted for Astronomy and Astrophysics, Supplement Serie

Mean curvature flow with triple junctions in higher space dimensions

We consider mean curvature flow of n-dimensional surface clusters. At (n-1)-dimensional triple junctions an angle condition is required which in the symmetric case reduces to the well-known 120 degree angle condition. Using a novel parametrization of evolving surface clusters and a new existence and regularity approach for parabolic equations on surface clusters we show local well-posedness by a contraction argument in parabolic Hoelder spaces.Comment: 31 pages, 2 figure

V39: an unusual object in the field of IC 1613

The variable star V39 in the field of IC 1613 is discussed in the light of the available photometric and new spectroscopic data. It has strong emission Balmer lines, and the observed characteristics could be explained by a W Vir pulsating star with a period of 14.341 d, located at more than 115 kpc, that is in the very outer halo of our Galaxy. It should have an apparent companion, a long period (1118d) red variable, belonging to IC 1613. The main uncertainty in this interpretation is an emission feature at 668.4 nm, which we tentatively identified as a He I line.Comment: 5 pages; accepted for publication in Astronomy & Astrophysic

Role of the tricuspid annulus in functional tricuspid regurgitation development after early isolated mitral valve surgery: is it an old story?

Abstract Funding Acknowledgements Type of funding sources: None. Background. Functional Tricuspid Regurgitation (FTR) has been described as a common condition after isolated mitral valve (MV) surgery, affecting patients' prognosis. Thus, in cases without significant tricuspid regurgitation (TR) but tricuspid annular (TA) dilatation, TV annuloplasty is currently recommended. Studies suggesting the currently used cut-off for definition of TA dilatation were based on 2D echocardiography (2DE) and included patients treated with MV surgery with heterogeneous MV disease, degree of cardiac remodeling and heart rhythm. As the management of severe MR has moved towards an earlier surgical treatment, few data are available about the incidence of FTR in the population undergoing early isolated MV surgery without TR, but 2DE satisfying criteria for TA dilatation. Aims. To test, in patients treated with early isolated MV surgery for MV prolapse (MVP), without TR and either normal or dilated TA (i) if the currently used 2D TA cut-off is predictive of FTR and cardiac events development (ii) how right chambers' remodeling assessed by 3D echocardiography (3DE) affects TA dimension. Methods. We studied 159 patients (age 61 ± 11) treated with early isolated MV surgery between 2010 and 2017. Eligible patients were those with 3DE images; normal left and right ventricular (LV and RV) function; sinus rhythm; normal or elevated right ventricular systolic pulmonary artery pressure (sPAP); normal or dilated TA by 2DE; absent TR. The decision to not perform TV annuloplasty in patients with TA dilatation was based on the surgical inspection. All patients underwent a complete 2DE, 3DE analysis was performed using custom software, including LV, RV, left atrial (LA) and right atrial (RA) assessment. 3D TA dimension were obtained using MPR. Clinical and 2DE follow-up was performed at 36 ± 6 months after surgery, major adverse cardiac events (MACEs, including cardiac hospitalization, cardiac death, arrhythmias) and FTR were recorded. Results. Based on 2DE TA dimensions, patients were divided in group 1 (N = 68, 43%, TA≥21 mm/m²) and group 2 (N= 91, 57%, normal TA). Patients in group 1 showed larger RA volume, RV basal diameter and TA area (p &lt; 0.05) by 3DE compared to group 2 (Table). At the multivariate analysis, only the 3D RA volume, RV basal diameter and RV function were independently correlated to the TA area (p &lt; 0.05). At the follow-up, no differences were noted between groups in FTR development and MACEs at the Kaplan-Meier analysis (Fig.). At the COX analysis, 2DE TA dilatation failed to result a predictor of cardiovascular events (model's X2, p &gt; 0.05). Conclusions. In patients undergoing early MV surgery, the currently defined TA dilatation by 2DE may not necessarily evolve in FTR, and a larger cut-off may be needed. In this population, the evaluation of right chambers' dimension and function may better define the probability to develop FTR. Abstract Figure. Fi

Metal enrichment in elliptical galaxies and globular clusters through the study of iron and H-beta spectral indices

Chemical evolution of elliptical galaxies and globular clusters is addressed through a combined study of the iron indices at 5270 and 5335 A, and of the H-Beta line strength. The observational database of 74 standard stars (both dwarfs and giants) referred to in a previous paper (Buzzoni et al. (1992)) complemented with the data of Faber et al. (1985) and Gorgas et al. (1993) allowed us to explore here Fe and H-Beta index dependence on stellar temperature, gravity, and metallicity. The derived fitting functions were then included into Buzzoni's (1989) code for population synthesis in order to derive expected integrated indices for simple stellar populations and compare with observations. Partition of metals in the current chemical mix of galaxies and globulars has been constrained supporting the claim that light alpha elements might be enhanced in the globular cluster metal-poor population. An alternative conclusion resting on the standard framework with (alpha/Fe) = 0 would require a systematically larger age, about 18-20 Gyr. Iron and magnesium in ellipticals are found in average solar but a systematic trend of (Mg/Fe) vs global metallicity does exist with iron more deficient with respect to magnesium at high Z. We conclude that this effect might indicate that Fe abundance per unit mass in the galaxies is constant (suggesting a constant rate per unit mass of SN I events) while light metals supplied by SNe II should have been more effectively enriched with increasing galactic total mass

Translocation pathways for inhaled asbestos fibers

We discuss the translocation of inhaled asbestos fibers based on pulmonary and pleuro-pulmonary interstitial fluid dynamics. Fibers can pass the alveolar barrier and reach the lung interstitium via the paracellular route down a mass water flow due to combined osmotic (active Na+ absorption) and hydraulic (interstitial pressure is subatmospheric) pressure gradient. Fibers can be dragged from the lung interstitium by pulmonary lymph flow (primary translocation) wherefrom they can reach the blood stream and subsequently distribute to the whole body (secondary translocation). Primary translocation across the visceral pleura and towards pulmonary capillaries may also occur if the asbestos-induced lung inflammation increases pulmonary interstitial pressure so as to reverse the trans-mesothelial and trans-endothelial pressure gradients. Secondary translocation to the pleural space may occur via the physiological route of pleural fluid formation across the parietal pleura; fibers accumulation in parietal pleura stomata (black spots) reflects the role of parietal lymphatics in draining pleural fluid. Asbestos fibers are found in all organs of subjects either occupationally exposed or not exposed to asbestos. Fibers concentration correlates with specific conditions of interstitial fluid dynamics, in line with the notion that in all organs microvascular filtration occurs from capillaries to the extravascular spaces. Concentration is high in the kidney (reflecting high perfusion pressure and flow) and in the liver (reflecting high microvascular permeability) while it is relatively low in the brain (due to low permeability of blood-brain barrier). Ultrafine fibers (length < 5 μm, diameter < 0.25 μm) can travel larger distances due to low steric hindrance (in mesothelioma about 90% of fibers are ultrafine). Fibers translocation is a slow process developing over decades of life: it is aided by high biopersistence, by inflammation-induced increase in permeability, by low steric hindrance and by fibers motion pattern at low Reynolds numbers; it is hindered by fibrosis that increases interstitial flow resistances

Pretransitional behavior in a water-DDAB-5CB microemulsion close to the demixing transition. Evidence for intermicellar attraction mediated by paranematic fluctuations

We present a study of a water-in-oil microemulsion in which surfactant coated water nanodroplets are dispersed in the isotropic phase of the thermotropic liquid crystal 5CB. As the temperature is lowered below the isotropic to nematic phase transition of pure 5CB, the system displays a demixing transition leading to a coexistence of a droplet rich isotropic phase with a droplet poor nematic. The transition is anticipated, in the high T side, by increasing pretransitional fluctuations in 5CB molecular orientation and in the nanodroplet concentration. The observed phase behavior supports the notion that the nanosized droplets, while large enough for their statistical behavior to be probed via light scattering, are also small enough to act as impurities, disturbing the local orientational ordering of the liquid crystal and thus experiencing pretransitional attractive interaction mediated by paranematic fluctuations. The pretransitional behavior, together with the topology of the phase diagram, can be understood on the basis of a diluted Lebwohl-Lasher model which describes the nanodroplets simply as holes in the liquid crystal.Comment: 64 pages, 16 figures, J. Chem. Phys. in pres