A Simple Model for the Absorption of Starlight by Dust in Galaxies

We present a new model to compute the effects of dust on the integrated spectral properties of galaxies, based on an idealized prescription of the main features of the interstellar medium (ISM). The model includes the ionization of HII regions in the interiors of the dense clouds in which stars form and the influence of the finite lifetime of these clouds on the absorption of radiation. We compute the production of emission lines and the absorption of continuum radiation in the HII regions and the subsequent transfer of line and continuum radiation in the surrounding HI regions and the ambient ISM. This enables us to interpret simultaneously all the observations of a homogeneous sample of nearby UV-selected starburst galaxies, including the ratio of far-IR to UV luminosities, the ratio of Halpha to Hbeta luminosities, the Halpha equivalent width, and the UV spectral slope. We show that the finite lifetime of stellar birth clouds is a key ingredient to resolve an apparent discrepancy between the attenuation of line and continuum photons in starburst galaxies. In addition, we find that an effective absorption curve proportional to lambda^-0.7 reproduces the observed relation between the ratio of far-IR to UV luminosities and the UV spectral slope. We interpret this relation most simply as a sequence in the overall dust content of the galaxies. The shallow wavelength dependence of the effective absorption curve is compatible with the steepness of known extinction curves if the dust has a patchy distribution. In particular, we find that a random distribution of discrete clouds with optical depths similar to those in the Milky Way provides a consistent interpretation of all the observations. Our model for absorption can be incorporated easily into any population synthesis model. (abridged)Comment: To appear in the 2000 July 20 issue of the Astrophysical Journal; 19 pages with 13 embedded PS figures (emulateapj5.sty

BioGlue® is not associated with polypropylene suture breakage after aortic surgery

Objective: We have encountered broken or damaged polypropylene sutures (Prolene®) at the anastomotic sites during aortic reoperations. Because a surgical sealant, bovine serum albumin-glutaraldehyde (BioGlue®), was used in previous aortic surgery in some of these cases, we undertook this in vitro study to evaluate whether the use of BioGlue® was associated with breakage of polypropylene sutures at the aortic anastomosis. Materials and methods: The broken polypropylene sutures, anastomotic sites and aortic tissue at the location of suture breakage were visually inspected and evaluated intraoperatively. Six human cadaveric aortic samples were incised circumferentially and anastomosed proximally to a valved conduit with running 4–0 polypropylene sutures (Prolene®). In the test group (n = 3), BioGlue® was applied directly to the Prolene® sutures at the anastomotic sites, while in the control group (n = 3) the anastomoses were not sealed with any surgical adhesive. The six samples were immersed in Dulbecco's phosphate buffered saline solution and mounted on a M-6 Six Position Heart Valve Durability Testing System and tested up to 120 million cycles for a 2-year period. During and upon completion of the testing, the integrity of Prolene® sutures, the anastomosis and aortic tissues was regularly assessed by visual inspection. Results: Intraoperative findings included a stretched and thin aortic wall (some with thrombus), a small cleft between the aortic tissue and the Dacron vascular graft. An excessive amount of BioGlue® was often found around the anastomosis, with cracking material, but no signs of mechanical damage were observed in these cases. Upon visual inspection during and after in vitro testing, there was no apparent damage to the polypropylene sutures on the interior or exterior of the aortic anastomoses in any of the samples. No difference was observed in the physical integrity of the polypropylene sutures at anastomotic lines, the anastomoses and aortic tissues between the test and control samples. Conclusions: The results of this study suggest that the use of BioGlue® was not associated with breakage of the polypropylene sutures at the anastomotic sites after aortic dissection repair

Bromodomain and extraterminal domain (BET) protein inhibition hinders glioblastoma progression by inducing autophagy-dependent differentiation

Glioblastoma multiforme (GBM) is the most common and aggressive type of malignant primary brain tumor, and it is characterized by a high recurrence incidence and poor prognosis due to the presence of a highly heterogeneous mass of stem cells with self-renewal capacity and stemness maintenance ability. In recent years, the epigenetic landscape of GBM has been explored and many epigenetic alterations have been investigated. Among the investigated epigenetic abnormalities, the bromodomain and extra-terminal domain (BET) chromatin readers have been found to be significantly overexpressed in GBM. In this work, we investigated the effects of BET protein inhibition on GBM cell reprogramming. We found that the pan-BET pharmacological inhibitor JQ1 was able to promote a differentiation program in GBM cells, thus impairing cell proliferation and enhancing the toxicity of the drug Temozolomide (TMZ). Notably, the pro-differentiation capability of JQ1 was prevented in autophagy-defective models, suggesting that autophagy activation is necessary for BET protein activity in regulating glioma cell fate. Given the growing interest in epigenetic therapy, our results further support the possibility of introducing a BET-based approach in GBM clinical management

Colorimetric Test for Fast Detection of SARS-CoV-2 in Nasal and Throat Swabs

Mass testing is fundamental to face the pandemic caused by the coronavirus SARS-CoV-2 discovered at the end of 2019. To this aim, it is necessary to establish reliable, fast, and cheap tools to detect viral particles in biological material so to identify the people capable of spreading the infection. We demonstrate that a colorimetric biosensor based on gold nanoparticle (AuNP) interaction induced by SARS-CoV-2 lends itself as an outstanding tool for detecting viral particles in nasal and throat swabs. The extinction spectrum of a colloidal solution of multiple viral-target gold nanoparticles-AuNPs functionalized with antibodies targeting three surface proteins of SARS-CoV-2 (spike, envelope, and membrane)-is red-shifted in few minutes when mixed with a solution containing the viral particle. The optical density of the mixed solution measured at 560 nm was compared to the threshold cycle (Ct) of a real-time PCR (gold standard for detecting the presence of viruses) finding that the colorimetric method is able to detect very low viral load with a detection limit approaching that of the real-time PCR. Since the method is sensitive to the infecting viral particle rather than to its RNA, the achievements reported here open a new perspective not only in the context of the current and possible future pandemics, but also in microbiology, as the biosensor proves itself to be a powerful though simple tool for measuring the viral particle concentration

Assessment of oxidative potential of fine aerosols from different indoor and outdoor environments

Trabalho apresentado em European Aerosol Conference 2023 (EAC2023), September 3−8, 2023, Malaga, SpainN/

On the Propagation of Slip Fronts at Frictional Interfaces

The dynamic initiation of sliding at planar interfaces between deformable and rigid solids is studied with particular focus on the speed of the slip front. Recent experimental results showed a close relation between this speed and the local ratio of shear to normal stress measured before slip occurs (static stress ratio). Using a two-dimensional finite element model, we demonstrate, however, that fronts propagating in different directions do not have the same dynamics under similar stress conditions. A lack of correlation is also observed between accelerating and decelerating slip fronts. These effects cannot be entirely associated with static local stresses but call for a dynamic description. Considering a dynamic stress ratio (measured in front of the slip tip) instead of a static one reduces the above-mentioned inconsistencies. However, the effects of the direction and acceleration are still present. To overcome this we propose an energetic criterion that uniquely associates, independently on the direction of propagation and its acceleration, the slip front velocity with the relative rise of the energy density at the slip tip.Comment: 15 pages, 6 figure

Oxidative potential of fine aerosols from a Portuguese urban-industrial area

Trabalho apresentado em NInTec Science Days, 6-7 October 2022, Lisboa, PortugalN/

Pollution sources affecting oxidative potential of fine aerosols from a Portuguese urban-industrial area

Trabalho apresentado em European Aerosol Conference 2023 (EAC2023), September 3−8, 2023, Malaga, SpainN/

An exploratory study for the implementation of the oxidative potential assessment of particulate matter in Portugal

Particulate matter (PM) is a harmful air pollutant that damages human health by inducing oxidative stress through the excessive generation of reactive oxygen species (ROS). Oxidative Potential (OP) is a proposed metric to measure PM's capacity to generate ROS (Almetwally et al., 2020; Jiang et al., 2019). This study aims to implement the OPDTT assessment methodology at C2TN (Portugal). A set of PM2.5 samples was evaluated using a widely used protocol (Chirizzi et al., 2017), and the results were compared to the values previously obtained at DISTEBA, where the protocol is well established. Moreover, the use of the reference material SRM 1648 (Urban Particulate) as a standard for determining OPDTT was also evaluated. Analyzing a 10 mg.L-1 solution of the reference material, it was possible to conclude that the standard solution presented an average DTT activity (normalized to the mass) value of 27.60 ± 3.79 pmol.min-1.μg-1.info:eu-repo/semantics/publishedVersio