Molecular dynamics in polymeric systems

It is well known that the properties of polymeric materials depend strongly upon their chemical structure. Other more specific factors that may be related to the chemical structure also determine the macroscopic behaviour of such materials, namely the relative position of the different segments of the polymeric chain, the molecular architecture (molecular weight distribution, branching, copoly-mer organisation, cross-linking extent, etc.), the crystalline environment and the pressure/temperature conditions. All these factors have a common impact in the material: they are strongly correlated to the mobility on the molecular level. That is why a huge amount of work has been devoted to the study of translational/rota-tional mobility that occurs within the polymeric chains. This review is intended to provide a brief survey on such kinds of mobilities, how they can be studied and what are their main characteristics. Examples on systems studied in our groups will be provided, obtained by dielectric and mechanical spectroscopies and differential scanning calorimetry. It will be mainly focused on molecular motions that occur in the solid phase (i.e., to temperatures up to the rubbery plateau). The dynamics in blends or copolymers will be avoided here, as they would deserve a special dis-cussion in their own context. Special attention will be paid to the glass transition and the mobility that occurs below and above it. The dynamics that are observed in peculiar systems, such as semi-crystalline or liquid crystalline polymers, will be addressed

Muller's ratchet in random graphs and scale free networks

Muller's ratchet is an evolutionary process that has been implicated in the extinction of asexual species, the evolution of mitochondria, the degeneration of the Y chromosome, the evolution of sex and recombination and the evolution of microbes. Here we study the speed of Muller's ratchet in a population subdivided into many small subpopulations connected by migration, and distributed on a network. We compare the speed of the ratchet in two distinct types of topologies: scale free networks and random graphs. The difference between the topologies is noticeable when the average connectivity of the network and the migration rate is large. In this situation we observe that the ratchet clicks faster in scale free networks than in random graphs. So contrary to intuition, scale free networks are more prone to loss of genetic information than random graphs. On the other hand, we show that scale free networks are more robust to the random extinction than random graphs. Since these complex networks have been shown to describe well real-life systems, our results open a framework for studying the evolution of microbes and disease epidemics

Experimentation with radio environment maps for resources optimisation in dense wireless scenarios

The rapidly increasing popularity of WiFi has created unprecedent levels of congestion in the unlicensed frequency bands, especially in densely populated urban areas. This results mainly because of the uncoordinated operation and the unmanaged interference between WiFi access points. Recently, Radio Environment Maps (REM) have been suggested as a support for coordination strategies that optimize the overall WiFi network performance. Despite some theoretical work done in this area, there are no clear experimental evidences of the benefit brought by WiFi coordination. In this context, the main objective of this experiment is to assess the benefit of a coordinated management of radio resources in dense WiFi networks using REMs for indoor scenarios. This experiment has used the w-iLab.t test environment provided by iMINDS, a cognitive-radio testbed for remote experimentation. It was shown that REMs are capable of detecting the presence of interfering links on the network (co-channel or adjacent channel interference), and a suitable coordination strategy can use this information to reconfigure Access Points (AP) channel assignment and reestablish the client connection. The coordination strategy almost double the capacity of a WiFi link under strong co–channel interference, from 6.8 Mbps to 11.8 Mbps, increasing the aggregate throughput of the network from 58.7 Mbps to 71.5 Mbps. However, this gain comes with the cost of a relatively high density network of spectrum sensors (12 sensors for an area of 60 × 20 m), increasing the cost of deployment.info:eu-repo/semantics/publishedVersio

Paediatric visceral leishmaniasis: experience of a paediatric referral center 1990-2009

INTRODUCTION: Visceral Leishmaniasis (VL) is a systemic infection, endemic in many parts of the world, including Portugal. The aim is to review all cases of VL admitted to our hospital. PATIENTS AND METHODS: Retrospective analysis of all cases of VL admitted to a Level III Paediatric Hospital, between January 1990 and December 2009 (20 years). Demographic, epidemiological, clinical, laboratorial, therapeutic and follow-up data were analysed. RESULTS: During the study period, 54 children were admitted with VL, three of which were excluded from the study due to incomplete clinical records. The mean age was 27 months (seven months - twelve years) and 53% were female. Two thirds of the cases were diagnosed during Spring and Summer. The mean time for diagnosis was 31 days (2-188 days). The most common clinical findings were splenomegaly (100%), fever (96%), pallor (90%) and hepatomegaly (82%). Bone marrow aspiration was performed in all children, with amastigotes identified in 73% of the cases. Indirect immunofluorescence was performed in 30 cases, being positive in 29 (97%). All were treated with meglumine antimoniate. Three children relapsed during the first year after the initial episode. A 17 months-old child died due to cardiac failure. CONCLUSIONS: The early diagnosis of VL is essential to carry out prompt management and prevent potential fatal complications. In our analysis, the management with meglumine antimoniate resulted in an overall favourable outcom

Characterization of suspension poly(vinyl chloride) resins and narrow polystyrene standards by size exclusion chromatography with multiple detectors: Online right angle laser-light scattering and differential viscometric detectors

This work reports the utilization of a multi-detector size chromatography for the characterization of poly(vinyl chloride) (PVC) resins prepared by suspension polymerization in the range of temperatures between 21 and 75 °C. The chromatography equipment offers the possibility of analyzing the samples in terms of their absolute molecular mass using a combination of three detectors (TriSEC): right angle light scattering (RALLS), a differential viscometer (DV) and refractive index (RI). The PVC resins were fully characterized concerning the molecular weight distribution (MWD), its dependence with intrinsic viscosity ([eta]) and molecular sizes (radius of gyration, Rg and hydrodynamic radius, Rh). Additionally, it is also presented the characterization of polystyrene narrow standards serving as reference polymers.http://www.sciencedirect.com/science/article/B6TWW-4HHGNVH-4/1/170871b80274a89470f2a790d3ed999

Pre- and post-COVID practice of interventional pulmonology in adults in Portugal

Funding Information: We thank Prime Focus for providing language help and writing assistance to this article. Publisher Copyright: © 2022 Sociedade Portuguesa de PneumologiaIntroduction and objectives: There is a lack of information regarding bronchoscopy practice in adults in Portugal. Our objective was to obtain an overview of the characteristics, resources, techniques and behaviors in national interventional pulmonology (IP) units, before and after SARS-CoV-2 outbreak. Materials and Methods: An online survey was developed by an expert panel with a total of 46 questions comprising the specifications of each unit, namely physical space, equipment, staff, procedure planning, monitoring, technical differentiation, and numbers pre- and post-COVID-19. Forty-one interventional pulmonology centers were invited to participate between April and May 2021. Results: 37 units (90.2%) responded to the survey. The majority (64.9%) have a fully dedicated space with a weekly presence of ≥3 chest physicians (82.1%) and support of an anesthesiologist on specific days (48.6%). There is marked heterogeneity in the IP unit's equipment, and 56.8% acquired disposable bronchoscopes after COVID-19 pandemics. Pre-bronchoscopy hemogram, platelet count and coagulation tests are regularly asked by more than 90% of the units, even when deep sedation or biopsies are not planned. In 97.3% of cases, topical anesthesia and midazolam are utilized. Propofol (21.6%) and fentanyl (29.7%) are occasionally employed in some institutions. Most units use ancillary sampling techniques to diagnose central or peripheral lesions, with radial EBUS being used for guidance of distal procedures in 37.8% of centers, linear EBUS and EUS-B-FNA for mediastinal diagnosis and/or staging in 45.9% and 27.0% of units, respectively. Cryobiopsies are used by 21.6% of respondents to diagnose diffuse lung diseases. Rigid bronchoscopy is performed in 37.8% of centers. There was a decrease in the number of flexible (p < 0.001) and rigid (p = 0.005) bronchoscopies and an upscale of personal protective equipment (PPE) during the COVID-19 outbreak. Conclusions: IP units have variable bronchoscopic practices, but during the COVID-19 pandemic, they complied with most international recommendations, as elective procedures were postponed and PPE levels increased.proofepub_ahead_of_prin

Determination of phytoextraction potential of plant speciesfor toxic elements in soils of abandoned sulphide-mining areas

This study has determined contamination levels in soils and plants from the Sa˜o Domingos mining area, Portugal, by k0-INAA. Total concentrations of As, Sb, Cr, Hg, Cu, Zn and Fe in soils were very high, exceeding the maximum limits in Portuguese legislation. Concentrations of toxic elements like As, Sb and Zn were highest in roots of Erica andevalensis, Juncus acutus, Agrostis castellana and Nicotiana glauca. Additionally, As, Br, Cr, Fe, Sb and Zn in all organs of most plants were above toxicity levels. Those species that accumulated relatively high concentrations of toxic elements in roots (and tops) may be cultivated for phytostabilisation of similar areas

Right Atrial Thrombus: a Rare Presentation of Plasminogen Activator Inhibitor Deficiency

A presença de trombos móveis na aurícula direita são fenómenos raros, mas associados a uma elevada mortalidade. Apesar de a ecocardiografia ter permitido avanços no seu diagnóstico, a sua abordagem continua a ser motivo de debate. Neste artigo apresentamos o caso de uma doente do sexo feminino, de 24 anos, com antecedentes de tabagismo, obesidade e sob terapêutica anovulatória que recorre ao serviço de urgência por cansaço fácil e tosse com expetoração hemoptoica. O ecocardiograma transtorácico revelou massa, móvel, multilobulada de grandes dimensões na aurícula direita, condicionando abertura da válvula tricúspide. Perante episódios recorrentes de embolia pulmonar, foi submetida a cirurgia cardíaca com exérese da massa, sendo o resultado anatomopatológico compatível com trombo organizado com calcificação. O estudo genético revelou homozigotia para a variante alélica PAI-1:-675G >A(4G/4G) do inibidor do ativador do plasminogénio e heterozigotia para a variante alélica MTHFR 1298 A/C da 5,10-metilenotetrahidrofolato redutase