198 research outputs found

    A Cesàro average for an additive problem with an arbitrary number of prime powers and squares

    Get PDF
    In this paper we extend and improve all the previous results known in literature about weighted average, with Cesàro weight, of representations of an integer as sum of a positive arbitrary number of prime powers and a non-negative arbitrary number of squares. Our result includes all cases dealt with so far and allows us to obtain the best possible outcome using the chosen technique

    Laser-Induced Graphenization of PDMS as Flexible Electrode for Microsupercapacitors

    Get PDF
    Laser graphenization of polymeric surfaces has emerged as one of the most promising technologies to fabricate flexible electrodes. Unfortunately, despite the large number of materials suitable for laser-induced graphene (LIG) fabrication, there is a lack of stretchable polymers, hindering the full exploitation of LIG for flexible electronics. Herein, the laser graphenization of polydimethylsiloxane (PDMS), the most exploited elastomeric substrate for flexible electronic device fabrication, is proposed for the first time. The low carbon content and the absence of aromatic structures strongly limit the graphenization process resulting in limited conduction properties. Nevertheless, by adding triethylene glycol (TEG) as carbon source into the PDMS matrix, it is possible to improve the graphenization and to reduce the sheet resistance of the written LIG by two orders of magnitude down to 130 ohm sq−1. The PDMS-TEG material becomes a suitable candidate for flexible microsupercapacitor fabrication with specific capacitance values as high as 287 µF cm−2 and energy and power density approaching LIG-based supercapacitors fabricated onto traditional polyimide substrates

    Tragacanth Gum as Green Binder for Sustainable Water-Processable Electrochemical Capacitor

    Get PDF
    Enabling green fabrication processes for energy storage devices is becoming a key aspect in order to achieve a sustainable fabrication cycle. Here, the focus was on the exploitation of the tragacanth gum, an exudated gum like arabic and karaya gums, as green binder for the preparation of carbon‐based materials for electrochemical capacitors. The electrochemical performance of tragacanth (TRGC)‐based electrodes was thoroughly investigated and compared with another water‐soluble binder largely used in this field, sodium‐carboxymethyl cellulose (CMC). Apart from the higher sustainability both in production and processing, TRGC exhibited a lower impact on the obstruction of pores in the final active material film with respect to CMC, allowing for more available surface area. This directly impacted the electrochemical performance, resulting in a higher specific capacitance and better rate capability. Moreover, the TRGC‐based supercapacitor showed a superior thermal stability compared with CMC, with a capacity retention of about 80 % after 10000 cycles at 70 °C

    Thermoplasmonic controlled optical absorber based on a liquid crystal metasurface

    Get PDF
    Metasurfaces can be realized by organizing subwavelength elements (e.g., plasmonic nanoparticles) on a reflective surface covered with a dielectric layer. Such an array of resonators, acting collectively, can completely absorb the resulting resonant wavelength. Unfortunately, despite the excellent optical properties of metasurfaces, they lack the tunability to perform as adaptive optical components. To boost the utilization of metasurfaces and realize a new generation of dynamically controlled optical components, we report our recent finding based on the powerful combination of an innovative metasurface-optical absorber and nematic liquid crystals (NLCs). The metasurface consists of self-assembled silver nanocubes (AgNCs) immobilized on a 50 nm thick gold layer by using a polyelectrolyte multilayer as a dielectric spacer. The resulting optical absorbers show a well-defined reflection band centered in the near-infrared of the electromagnetic spectrum (750-770 nm), a very high absorption efficiency (∼60%) at the resonant wavelength, and an elevated photothermal efficiency estimated from the time constant value (34 s). Such a metasurface-based optical absorber, combined with an NLC layer, planarly aligned via a photoaligned top cover glass substrate, shows homogeneous NLC alignment and an absorption band photothermally tunable over approximately 46 nm. Detailed thermographic studies and spectroscopic investigations highlight the extraordinary capability of the active metasurface to be used as a light-controllable optical absorber

    Exposure of Nonbreeding Migratory Shorebirds to Cholinesterase Inhibiting Contaminants in the Western Hemisphere

    Get PDF
    Migratory shorebirds frequently forage and roost in agricultural habitats, where they may be exposed to cholinesterase-inhibiting pesticides. Exposure to organophosphorus and carbamate compounds, common anti-cholinesterases, can cause sublethal effects, even death. To evaluate exposure of migratory shorebirds to organophosphorus and carbamates, we sampled birds stopping over during migration in North America and wintering in South America. We compared plasma Cholinesterase activities and body masses of individuals captured at sites with no known sources of organophosphorus or carbamates to those captured in agricultural areas where agrochemicals were recommended for control of crop pests. In South America, plasma acetylcholinesterase and butyrylcholinesterase activity in Buff-breasted Sandpipers was lower at agricultural sites than at reference sites, indicating exposure to organophosphorus and carbamates. Results of plasma Cholinesterase reactivation assays and foot-wash analyses were inconclusive. A meta-analysis of six species revealed no widespread effect of agricultural chemicals on Cholinesterase activity. However, four of six species were negative for acetylcholinesterase and one of six for butyrylcholinesterase, indicating negative effects of pesticides on Cholinesterase activity in a subset of shorebirds. Exposure to Cholinesterase inhibitors can decrease body mass, but comparisons between treatments and hemispheres suggest that agrochemicals did not affect migratory shorebirds' body mass. Our study, one of the first to estimate of shorebirds' exposure to cholinesterase-inhibiting pesticides, suggests that shorebirds are being exposed to cholinesterase-inhibiting pesticides at specific sites in the winter range but not at migratory stopover sites. Future research should examine potential behavioral effects of exposure and identify other potential sites and levels of exposure.Instituto de Recursos BiológicosFil: Strum, Khara M. Kansas State University. Division of Biology; Estados UnidosFil: Hooper, Michael J. Texas Tech University. Institute of Environmental and Human Health; Estados UnidosFil: Johnson, Kevin A. Southern Illinois University. Department of Chemistry and Environmental Sciences; Estados UnidosFil: Lanctot, Richard B. United State Fish and Wildlife Service. Migratory Bird Management; Estados UnidosFil: Zaccagnini, Maria Elena. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Sandercock, Brett K. Kansas State University. Division of Biology; Estados Unido

    Avian influenza and its implications for the health of South American wild birds

    Get PDF
    La Influenza Aviar Altamente Patógena se ha diseminado rápidamente desde 2003 en países de Asia, Europa y África, con serias consecuencias para la industria avícola, la salud pública y la salud de especies silvestres. El rol de las aves silvestres en el mantenimiento y dispersión geográfica de la enfermedad se mantiene incierto. Existe muy poca información sobre la presencia y la ecología de los virus de Influenza de tipo A en aves de América del Sur. En los últimos años, ocho subtipos virales no patógenos han sido aislados de aves acuáticas (Anseriformes y Charadriiformes) en Argentina, Perú, Chile y Brasil. Se desconocen los mecanismos involucrados en la perpetuación de tales virus, su potencial mutagénico hacia cepas patógenas y las consecuencias de su circulación en la región. Este trabajo resume los aspectos más sobresalientes de la información científica disponible sobre la ecoepidemiología de la Influenza Aviar que resultan de utilidad para comprender el impacto que esta enfermedad puede tener en la salud y en la conservación de la avifauna silvestre del Neotrópico.Since 2003, Avian Influenza has spread rapidly throughout countries of Asia, Europe and Africa, resulting in serious consequences for the poultry industry, public health and the health of wild species. The role of wild birds in the maintenance and geographical expansion of the disease is a matter of uncertainty. There is very little information about the occurrence and ecology of Influenza A viruses in South American birds. In recent years, eight low pathogenic viral subtypes have been isolated from waterbirds (Anseriformes and Charadriiformes) in Argentina, Peru, Chile and Brazil. The mechanisms involved in their maintenance, the potential to evolve into highly pathogenic strains and the consequences of their circulation in the region are unknown. This article reviews aspects of current scientific knowledge about the eco-epidemiology of Avian Influenza, which may be useful for understanding the impact that this disease could have on the health and conservation of Neotropical wild avifauna

    Tragacanth gum as green binder for sustainable water-processable electrochemical capacitor

    Get PDF
    9Enabling green fabrication processes for energy storage devices is becoming a key aspect in order to achieve a sustainable fabrication cycle. Here we focus on the exploitation of the tragacanth gum, an exudated gum like arabic and karaya gums, as green binder for the preparation of carbon-based for electrochemical capacitors. The electrochemical performance of tragacanth (TRGC)-based electrodes are thoroughly investigated and compared with another water-soluble binder largely used in this field, i.e. sodium-carboxymethyl cellulose (CMC). Apart from the higher sustainability both in production and processing, TRGC exhibits a lower impact on the obstruction of pores in the final active material film with respect to CMC, allowing for more available surface area. This directly impacts on the electrochemical performances resulting in a higher specific capacitance and better rate capability. Moreover, the TRGC-based supercapacitor shows a superior thermal stability than CMC with a capacity retention of about 80 % after 10.000 cycles at 70 °C.partially_openopenScalia, Alberto; Zaccagnini, Pietro; Armandi, Marco; Latini, Giulio; Versaci, Daniele; Lanzio, Vittorino; Varzi, Alberto; Passerini, Stefano; Lamberti, AndreaScalia, Alberto; Zaccagnini, Pietro; Armandi, Marco; Latini, Giulio; Versaci, Daniele; Lanzio, Vittorino; Varzi, Alberto; Passerini, Stefano; Lamberti, Andre

    Exploring the professionalization of respiratory therapy in Canada

    Get PDF
    Knowledge is believed to be essential in the evolution from occupation to profession and is valuable to a profession in three ways: it can influence the profession's legitimacy, it can be used for conducting research, and it promotes higher education. RTs possess jurisdictional professional autonomy within Canada. The privilege of self-regulation allows RTs to act according to their knowledge and judgement without direct oversight from other professions. CONCLUSION: Based on Abbott's theoretical position, RTs can rightly justify their position as professionals. However, RTs need to acknowledge that professionalization is a dynamic and continuous process that requires creative changes to innovate within the profession and support future efforts to reinforce their position as professionals. Throughout this paper, we offer suggestions for how RTs can contribute to the ongoing professionalization of respiratory therapy

    What scholarly practice means to respiratory therapists: An interpretive description study

    Get PDF
    Abstract Rationale Engagement in scholarly practice has been associated with professional empowerment, role satisfaction and improvements in care delivery and patient outcomes across many healthcare professions. However, in evolving professions like respiratory therapy, scholarly practice is excluded from competency frameworks, resulting in a gap in education and subsequent application of this competency in practice. An exploration of scholarly practice in respiratory therapy may provide insights into evolving professions that face tensions between meeting competency requirements as outlined in frameworks and providing quality healthcare to the populations they serve. Aims and Objectives The aim of the study was to explore what scholarly practice means, and how it manifests in practice from respiratory therapists' (RTs) perspectives. Methods We used interpretive description methodology. We purposively sampled participants to obtain varied perspectives of scholarly practice in respiratory therapy. We conducted 26 semistructured interviews with RTs in different roles (clinicians, educators, researchers, leaders and managers) across Canada and analysed the data using inductive analysis. Data collection and analysis proceeded concurrently. Results We developed five main themes: (i) the identity of a scholarly practitioner in RTs; (ii) factors influencing scholarly practice; (iii) one's impression of their professional self-image; (iv) scholarly practice as a vehicle for changing practice and (v) the complex interconnections between knowledges and practices. Conclusion Scholarly practice appears to be a multifaceted phenomenon encompassing a wide range of activities and skills including conducting research, reflective practice, application of research to practice, and contributing to the advancement of the profession and healthcare. Scholarly practice is influenced by organisational context and culture, available resources, intrinsic motivation and external political context. We identified similarities between professional identity and the description of the scholarly practitioner, suggesting that these two phenomena may be interconnected. Furthermore, participants believed that scholarly practice could enhance the image, credibility, legitimacy and professionalisation of the profession
    corecore