Analytical model of the acoustic response of nanogranular films adhering on a substrate

A 1D mechanical model for nanogranular films, based on a structural interface, is here presented. The analytical dispersion relation for the frequency and lifetimes of the acoustics breathing modes is obtained in terms of the interface layer thickness and porosity. The model is successfully benchmarked both against 3D Finite Element Method simulations and experimental photoacoustic data on a paradigmatic system available from the literature. A simpler 1D model, based on an homogenized interface, is also presented and its limitations and pitfalls discussed at the light of the more sophisticated pillar model. The pillar model captures the relevant physics responsible for acoustic dissipation at a disordered interface. Furthermore, the present findings furnish to the experimentalist an easy-to-adopt, benchmarked analytical tool to extract the interface layer physical parameters upon fitting of the acoustic data. The model is scale invariant and may be deployed, other than the case of granular materials, where a patched interface is involved

Photoacoustic Sensing of Trapped Fluids in Nanoporous Thin Films: Device Engineering and Sensing Scheme

Accessing fluid infiltration in nanogranular coatings is an outstanding challenge, of relevance for applications ranging from nanomedicine to catalysis. A sensing platform, allowing to quantify the amount of fluid infiltrated in a nanogranular ultrathin coating, with thickness in the 10 to 40 nm range, is here proposed and theoretically investigated by multiscale modelling. The scheme relies on impulsive photoacoustic excitation of hypersonic mechanical breathing modes in engineered gas-phase synthesised nanogranular metallic ultathin films and time-resolved acousto-optical read-out of the breathing modes frequency shift upon liquid infiltration. A superior sensitivity, exceeding 26x103 cm^2/g, is predicted upon equivalent areal mass loading of a few ng/mm^2. The capability of the present scheme to discriminate among different infiltration patterns is discussed. The platform is an ideal tool to investigate nano fluidics in granular materials and naturally serves as a distributed nanogetter coating, integrating fluid sensing capabilities. The proposed scheme is readily extendable to other nanoscale and mesoscale porous materials.Comment: 14 pages, 4 figure

Quantitative ultrasound applied to metacarpal bone in infants.

Aim. To provide bone status assessment in infancy using quantitative ultrasound (QUS) applied to second metacarpus.Methods. 103 healthy term infants and 3 patients with rickets, aged ≤ 12 months, underwent metacarpal QUS evaluation using QUS DBM Sonic Aurora IGEA (MO, Italy), which measures speed of sound (mcSOS) and bone transmission time (mcBTT).Results. In the total sample, median (interquartile range) of mcSOS was 1640.00 (26.0) m/s and mcBTT 0.82 (0.21) µs. Moreover, reference values for age were obtained based on estimation of the lower and upper percentiles. We observed a statistical significant difference between groups of age for mcSOS (p = 0.016). In a multiple linear regression model, we found a relation between age at enrolment and mcSOS (β = −0.608; p = 0.000) and mcBTT (β = −0.819; p = 0.001). A positive correlation between mcSOS and mcBTT has been observed (r = 0.631; p = 0.000). All the patients with rickets showed values of mcSOS and mcBTT lower than the 10th percentile.Conclusion. Our findings show that this new simple technique appears to be a promising tool for monitoring bone mineral status in pediatric clinical practice and in early life. Furthermore, it could be considered a useful method to investigate and to monitor the role of different factors on programming of bone health and it should be tested as a new method for monitoring subjects with rickets during therapy

Cosmological data and indications for new physics

Data from the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT), combined with the nine-year data release from the WMAP satellite, provide very precise measurements of the cosmic microwave background (CMB) angular anisotropies down to very small angular scales. Augmented with measurements from Baryonic Acoustic Oscillations surveys and determinations of the Hubble constant, we investigate whether there are indications for new physics beyond a Harrison-Zel'dovich model for primordial perturbations and the standard number of relativistic degrees of freedom at primordial recombination. All combinations of datasets point to physics beyond the minimal Harrison-Zel'dovich model in the form of either a scalar spectral index different from unity or additional relativistic degrees of freedom at recombination (e.g., additional light neutrinos). Beyond that, the extended datasets including either ACT or SPT provide very different indications: while the extended-ACT (eACT) dataset is perfectly consistent with the predictions of standard slow-roll inflation, the extended-SPT (eSPT) dataset prefers a non-power-law scalar spectral index with a very large variation with scale of the spectral index. Both eACT and eSPT favor additional light degrees of freedom. eACT is consistent with zero neutrino masses, while eSPT favors nonzero neutrino masses at more than 95% confidence.Comment: 13 pages, 5 figures, 2 table

Antimicrobial Nanostructured Coatings: A Gas Phase Deposition and Magnetron Sputtering Perspective

Counteracting the spreading of multi-drug-resistant pathogens, taking place through surface-mediated cross-contamination, is amongst the higher priorities in public health policies. For these reason an appropriate design of antimicrobial nanostructured coatings may allow to exploit dierent antimicrobial mechanisms pathways, to be specifically activated by tailoring the coatings composition and morphology. Furthermore, their mechanical properties are of the utmost importance in view of the antimicrobial surface durability. Indeed, the coating properties might be tuned dierently according to the specific synthesis method. The present review focuses on nanoparticle based bactericidal coatings obtained via magneton-spattering and supersonic cluster beam deposition. The bacteria\u2013NP interaction mechanisms are first reviewed, thus making clear the requirements that a nanoparticle-based film should meet in order to serve as a bactericidal coating. Paradigmatic examples of coatings, obtained by magnetron sputtering and supersonic cluster beam deposition, are discussed. The emphasis is on widening the bactericidal spectrum so as to be eective both against gram-positive and gram-negative bacteria, while ensuring a good adhesion to a variety of substrates and mechanical durability. It is discussed how this goal may be achieved combining dierent elements into the coating

Exploring the optical and morphological properties of ag and Ag/TiO2nanocomposites grown by supersonic cluster beam deposition

Nanocomposite systems and nanoparticle (NP) films are crucial for many applications and research fields. The structure-properties correlation raises complex questions due to the collective structure of these systems, often granular and porous, a crucial factor impacting their effectiveness and performance. In this framework, we investigate the optical and morphological properties of Ag nanoparticles (NPs) films and of Ag NPs/TiO2porous matrix films, one-step grown by supersonic cluster beam deposition. Morphology and structure of the Ag NPs film and of the Ag/TiO2(Ag/Ti 50-50) nanocomposite are related to the optical properties of the film employing spectroscopic ellipsometry (SE). We employ a simple Bruggeman effective medium approximation model, corrected by finite size effects of the nano-objects in the film structure to gather information on the structure and morphology of the nanocomposites, in particular porosity and average NPs size for the Ag/TiO2NP film. Our results suggest that SE is a simple, quick and effective method to measure porosity of nanoscale films and systems, where standard methods for measuring pore sizes might not be applicable

G protein–coupled receptor 21 in macrophages: An in vitro study

GPR21 is an orphan and constitutively active receptor belonging to the superfamily of G-Protein Coupled Receptors (GPCRs). GPR21 couples to the Gq family of G proteins and is markedly expressed in macrophages. Studies of GPR21 knock-out mice indicated that GPR21 may be involved in promoting macrophage migration. The aim of this study was to evaluate the role of GPR21 in human macrophages, analyzing (i) its involvement in cell migration and cytokine release and (ii) the consequence of its pharmacological inhibition by using the inverse agonist GRA2. THP-1 cells were activated and differentiated into either M1 or M2 macrophages. GPR21 expression was evaluated at gene and protein level, the signalling pathway was investigated by an IP1 assay, and cytokine release by ELISA. Cell migration was detected by the Boyden chamber migration assay, performed on macrophages derived from both the THP-1 cell line and human peripheral blood monocytes. In addition, we compared the effect of the pharmacological inhibition of GPR21 with the effect of the treatment with a specific GPR21 siRNA to downregulate the receptor expression, thus confirming that GRA2 acts as an inverse agonist of GPR21. GRA2 does not affect cell viability at the tested concentrations, but significantly reduces the release of TNF-α and IL-1β from M1 macrophages. The analysis of the migratory ability highlighted opposite effects of GRA2 on M1 and M2 macrophages since it decreased M1, while it promoted M2 cell migration. Therefore, the pharmacological inhibition of GPR21 could be of interest for pathological conditions characterized by low grade chronic inflammation

Radiation-hydrodynamical modelling of underluminous Type II plateau supernovae

With the aim of improving our knowledge about the nature of the progenitors of low-luminosity Type II plateau supernovae (LL SNe IIP), we made radiation-hydrodynamical models of the well-sampled LL SNe IIP 2003Z, 2008bk and 2009md. For these three SNe, we infer explosion energies of 0.16-0.18 foe, radii at explosion of 1.8-3.5 × 1013 cm and ejected masses of 10-11.3 M☉. The estimated progenitor mass on the main sequence is in the range ∼13.2-15.1 M☉ for SN 2003Z and ∼11.4-12.9 M☉ for SNe 2008bk and 2009md, in agreement with estimates from observations of the progenitors. These results together with those for other LL SNe IIP modelled in the same way enable us also to conduct a comparative study on this SN sub-group. The results suggest that (a) the progenitors of faint SNe IIP are slightly less massive and have less energetic explosions than those of intermediate-luminosity SNe IIP; (b) both faint and intermediate-luminosity SNe IIP originate from low-energy explosions of red (or yellow) supergiant stars of low to intermediate mass; (c) some faint objects may also be explained as electron-capture SNe from massive super-asymptotic giant branch stars; and (d) LL SNe IIP form the underluminous tail of the SNe IIP family, where the main parameter `guiding' the distribution seems to be the ratio of the total explosion energy to the ejected mass. Further hydrodynamical studies should be performed and compared to a more extended sample of LL SNe IIP before drawing any conclusion on the relevance of fall-back to this class of events

A Summary of Methods for Fire Tests of Roof Coverings

AbstractThe testing method about the fire performance of roof covering and materials has not been put into operation in China. This article focuses on two main international testing about fire performance of roof covering and materials, comparing the difference between the two test methods

Paclitaxel-Loaded Nanosponges Inhibit Growth and Angiogenesis in Melanoma Cell Models

This study investigated the effects of free paclitaxel (PTX) and PTX-loaded in pyromellitic nanosponges (PTX-PNS) in reducing in vitro and in vivo melanoma cell growth and invasivity, and in inhibiting angiogenesis. To test the response of cells to the two PTX formulations, the cell viability was evaluated by MTT assay in seven continuous cell lines, in primary melanoma cells, both in 2D and 3D cultures, and in human umbilical vein endothelial cells (HUVECs) after exposure to different concentrations of PTX or PTX-PNS. Cell motility was assessed by a scratch assay or Boyden chamber assay, evaluating cell migration in presence or absence of diverse concentrations of PTX or PTX-PNS. The effect of PTX and PTX-PNS on angiogenesis was evaluated as endothelial tube formation assay, a test able to estimate the formation of three-dimensional vessels in vitro. To assess the anticancer effect of PTX and PTX-PNS in in vivo experiments, the two drug formulations were tested in a melanoma mouse model obtained by B16-BL6 cell implantation in C57/BL6 mice. Results obtained were as follows: 1) MTT analysis revealed that cell proliferation was more affected by PTX-PNS than by PTX in all tested cell lines, in both 2D and 3D cultures; 2) the analysis of the cell migration showed that PTX-PNS acted at very lower concentrations than PTX; 3) tube formation assay showed that PTX-PNS were more effective in inhibiting tube formation than free PTX; and 4) in vivo experiments demonstrated that tumor weights, volumes, and growth were significantly reduced by PTX-PNS treatment with respect to PTX; the angiogenesis and the cell proliferation, detected in the tumor samples with CD31 and Ki-67 antibodies, respectively, indicated that, in the PTX-PNS-treated tumors, the tube formation was inhibited, and a low amount of proliferating cells was present. Taken together, our data demonstrated that our new PTX nanoformulation can respond to some important issues related to PTX treatment, lowering the anti-tumor effective doses and increasing the effectiveness in inhibiting melanoma growth in vivo