292 research outputs found

    Mass Transport in “Water-in-Polymer Salt” Electrolytes

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    “Water-in-polymer salt” electrolytes (WiPSEs) based on potassium polyacrylate (PAAK) belong to a new family of “water-in-salt” electrolytes that is envisioned as a potential solution for large-scale supercapacitors to balance the electric grid at short time scales. The WiPSEs display a broad electrochemical stability window up to 3 V, yet they are nonflammable and provide high ionic conductivity (100 mS/cm) as required in high-power devices. However, the transport of matter in PAAK-based WiPSEs has not been studied. In this work, we have extensively characterized PAAK by spectroscopic methods such as Raman spectroscopy and NMR diffusometry to determine the state of water and elucidate the mechanism of ionic transport as well as its interplay with water and polymer chain dynamics, which reveals that a significant proportion of the transport in WiPSEs is attributed to hydrated cations. The results are further supported by molecular dynamics (MD) simulations. Finally, the potential of WiPSEs based on PAAK is demonstrated in an activated carbon-based supercapacitor operating up to 2 V with reasonable self-discharge. This proof of concept shows promise for low-cost and large-scale supercapacitors

    ERICA: prevalência de tabagismo em adolescentes brasileiros

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    OBJECTIVE To estimate the prevalences of tobacco use, tobacco experimentation, and frequent smoking among Brazilian adolescents. METHODS We evaluated participants of the cross-sectional, nation-wide, school-based Study of Cardiovascular Risks in Adolescents (ERICA), which included 12- to 17-year-old adolescents from municipalities of over 100 thousand inhabitants. The study sample had a clustered, stratified design and was representative of the whole country, its geographical regions, and all 27 state capitals. The information was obtained with self-administered questionnaires. Tobacco experimentation was defined as having tried cigarettes at least once in life. Adolescents who had smoked on at least one day over the previous 30 days were considered current cigarette smokers. Having smoked cigarettes for at least seven consecutive days was an indicator for regular consumption of tobacco. Considering the complex sampling design, prevalences and 95% confidence intervals were estimated according to sociodemographic and socio-environmental characteristics. RESULTS We evaluated 74,589 adolescents. Among these, 18.5% (95%CI 17.7-19.4) had smoked at least once in life, 5.7% (95%CI 5.3-6.2) smoked at the time of the research, and 2.5% (95%CI 2.2-2.8) smoked often. Adolescents aged 15 to 17 years had higher prevalences for all indicators than those aged 12 to 14 years. The prevalences did not differ significantly between sexes. The highest prevalences were found in the South region and the lowest ones, in the Northeast region. Regardless of sex, the prevalences were found to be higher for adolescents who had had paid jobs, who lived with only one parent, and who reported having been in contact with smokers either inside or outside their homes. Female public school adolescents were found to smoke more than the ones from private schools. CONCLUSIONS Tobacco use among adolescents is still a challenge. Intending to reduce the prevalence of tobacco use among young people, especially the ones under socioeconomic vulnerability conditions, Brazil must consolidate and increase effective public health care measures.OBJETIVO Estimar as prevalências de tabagismo, experimentação e fumo frequente em adolescentes brasileiros. MÉTODOS Foram avaliados os participantes do Estudo de Riscos Cardiovasculares em Adolescentes (ERICA), estudo transversal de base escolar e abrangência nacional. Participaram adolescentes de 12 a 17 anos de municípios com mais de 100 mil habitantes. A amostra foi estratificada e conglomerada e tem representatividade nacional, regional e para as 27 capitais. As informações foram obtidas usando-se questionário autopreenchível. Experimentação foi definida como: ter experimentado cigarros alguma vez na vida. Foram considerados fumantes atuais de cigarros aqueles que fumaram pelo menos um dia nos últimos 30 dias. Utilizou-se como indicador de uso frequente de tabaco ter fumado cigarros por pelo menos sete dias seguidos. Considerando-se o desenho complexo da amostra, prevalências e intervalos de confiança de 95% foram estimados segundo características sociodemográficas e socioambientais. RESULTADOS Foram avaliados 74.589 adolescentes; dentre esses, 18,5% (IC95% 17,7-19,4) fumaram pelo menos uma vez na vida, 5,7% (IC95% 5,3-6,2) fumavam no momento da pesquisa e 2,5% (IC95% 2,2-2,8) fumavam com frequência. Adolescentes de 15 a 17 anos tiveram prevalências mais elevadas de todos os indicadores comparados aos de 12 a 14 anos. As prevalências não apresentaram diferenças significativas entre sexos. Maiores prevalências foram observadas na região Sul e menores na região Nordeste. Independentemente de sexo, as prevalências foram maiores para adolescentes que tinham tido trabalho remunerado, nos que não moravam com os dois pais e que referiram ter tido contato com fumante em casa ou fora. Adolescentes do sexo feminino de escolas públicas fumavam mais do que as de escolas privadas. CONCLUSÕES O tabagismo entre adolescentes ainda é um desafio. Visando a redução da prevalência de tabagismo entre jovens, em especial os que se encontram em situação de vulnerabilidade socioeconômica, o Brasil deve consolidar e ampliar medidas de saúde pública efetivas

    [Prevalence of tobacco use and associated factors among women in Parana State, Brazil]

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    This study aimed to estimate the prevalence of tobacco use and to describe the demographic profile of female smokers in Parana State, Brazil. The study used a cross-sectional population-based design with cluster sampling (n = 2,153) of women 18 years or older in seven cities. Prevalence of smoking was 13.4%, ranging from 10% in Cascavel to 19% in Irati. According to multivariate analysis, city of residence, marital status, and schooling were significantly associated with tobacco use. Women in Irati (OR = 2.08; 95%CI: 1.22-3.54) were more likely to smoke than those in Cambe. Married women and widows were less likely to smoke (OR = 0.47; 95%CI: 0.30-0.73 and OR = 0.43; 95%CI: 0.22-0.87) than single women. Women living with a partner (but not married) were more likely to smoke than single women (OR = 2.49; 95%CI: 1.12-5.53), and women with university degrees were less likely to smoke than those with eight years of school or less (OR = 0.41; 95%CI: 0.22-0.87). The results confirm the need for tobacco control programs that take gender and regional differences into account

    Electronic and optical properties of lead iodide

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    ABSTRACT: Lead iodide (PbI2) is a very important material with a technological applicability as a room-temperature radiation detector. It is a wide-band-gap semiconductor (Eg.2 eV) with high environmental stability efficiency. The performance of the detector cannot be fully understood unless its electronic and optical properties are determined. Recently, its band-gap energy and thermal properties were determined by photoacoustic spectroscopy. A single crystal of PbI2 was grown by the Bridgman method with the c-axis oriented perpendicular to the growth axis. The purpose of this work is to obtain the electronic structure of PbI2, its dielectric functions e 1 and e 2 by ellipsometry and theoretically by full-potential linear muffin-tinorbital ~FPLMTO! method, and the temperature dependence of the measured band-gap energy by optica absorption. The obtained Eg(T) can be fitted by two different methods, leading to Eg ~0 K! and Eg ~300 K!

    ERICA: prevalências de hipertensão arterial e obesidade em adolescentes brasileiros

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    OBJECTIVE To estimate the prevalence of arterial hypertension and obesity and the population attributable fraction of hypertension that is due to obesity in Brazilian adolescents. METHODS Data from participants in the Brazilian Study of Cardiovascular Risks in Adolescents (ERICA), which was the first national school-based, cross-section study performed in Brazil were evaluated. The sample was divided into 32 geographical strata and clusters from 32 schools and classes, with regional and national representation. Obesity was classified using the body mass index according to age and sex. Arterial hypertension was defined when the average systolic or diastolic blood pressure was greater than or equal to the 95th percentile of the reference curve. Prevalences and 95% confidence intervals (95%CI) of arterial hypertension and obesity, both on a national basis and in the macro-regions of Brazil, were estimated by sex and age group, as were the fractions of hypertension attributable to obesity in the population. RESULTS We evaluated 73,399 students, 55.4% female, with an average age of 14.7 years (SD = 1.6). The prevalence of hypertension was 9.6% (95%CI 9.0-10.3); with the lowest being in the North, 8.4% (95%CI 7.7-9.2) and Northeast regions, 8.4% (95%CI 7.6-9.2), and the highest being in the South, 12.5% (95%CI 11.0-14.2). The prevalence of obesity was 8.4% (95%CI 7.9-8.9), which was lower in the North region and higher in the South region. The prevalences of arterial hypertension and obesity were higher in males. Obese adolescents presented a higher prevalence of hypertension, 28.4% (95%CI 25.5-31.2), than overweight adolescents, 15.4% (95%CI 17.0-13.8), or eutrophic adolescents, 6.3% (95%CI 5.6-7.0). The fraction of hypertension attributable to obesity was 17.8%. CONCLUSIONS ERICA was the first nationally representative Brazilian study providing prevalence estimates of hypertension in adolescents. Regional and sex differences were observed. The study indicates that the control of obesity would lower the prevalence of hypertension among Brazilian adolescents by 1/5.OBJETIVO Estimar as prevalências de hipertensão arterial e obesidade e a fração atribuível populacional de hipertensão arterial devida à obesidade em adolescentes brasileiros. MÉTODOS Foram avaliados dados dos participantes do Estudo de Riscos Cardiovasculares em Adolescentes, estudo seccional l nacional de base escolar. A amostra foi dividida em 32 estratos geográficos e conglomerados de escolas e turmas, com representatividade nacional, macrorregional e de capitais. Obesidade foi classificada pelo índice de massa corporal segundo idade e sexo. Considerou-se hipertensão arterial a média da pressão arterial sistólica ou diastólica maior ou igual ao percentil 95 da curva de referência. Foram estimadas prevalências e intervalos de confiança de 95% (IC95%) de hipertensão arterial e de obesidade, nacionais e nas macrorregiões do País, por sexo e grupo etário, assim como as frações de hipertensão atribuíveis à obesidade na população. RESULTADOS Foram avaliados 73.399 estudantes, 55,4% do sexo feminino, com média de idade 14,7 anos (DP = 1,6). A prevalência de hipertensão arterial foi 9,6% (IC95% 9,0-10,3); sendo as mais baixas observadas nas regiões Norte, 8,4% (IC95% 7,7-9,2) e Nordeste, 8,4% (IC95% 7,6-9,2) e a mais alta na região Sul, 12,5% (IC95% 11,0-14,2). A prevalência de obesidade foi 8,4% (IC95% 7,9-8,9), mais baixa na região Norte e mais alta na Sul. As prevalências de hipertensão arterial e obesidade foram maiores no sexo masculino. Adolescentes com obesidade tiveram prevalência de hipertensão arterial mais elevada, 28,4% (IC95% 25,5-31,2), do que aqueles com sobrepeso, 15,4% (IC95% 13,8-17,0), ou eutróficos, 6,3% (IC95% 5,6-7,0). A fração de hipertensão arterial atribuível à obesidade foi de 17,8%. CONCLUSÕES O ERICA foi o primeiro estudo brasileiro com representatividade nacional a estimar a prevalência de hipertensão arterial aferida em adolescentes. A fração da prevalência de hipertensão arterial atribuível à obesidade mostrou que cerca de 1/5 dos hipertensos poderiam não ser hipertensos se não fossem obesos

    Susceptibility of adult cat fleas (Siphonaptera: Pulicidae) to insecticides and status of insecticide resistance mutations at the Rdl and knockdown resistance loci

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    This is an Open Access article. © 2015 The Author(s). Published by Springer Berlin Heidelberg.The susceptibility of 12 field-collected isolates and 4 laboratory strains of cat fleas, Ctenocephalides felis was determined by topical application of some of the insecticides used as on-animal therapies to control them. In the tested field-collected flea isolates the LD50 values for fipronil and imidacloprid ranged from 0.09 to 0.35 ng/flea and 0.02 to 0.19 ng/flea, respectively, and were consistent with baseline figures published previously. The extent of variation in response to four pyrethroid insecticides differed between compounds with the LD50 values for deltamethrin ranging from 2.3 to 28.2 ng/flea, etofenprox ranging from 26.7 to 86.7 ng/flea, permethrin ranging from 17.5 to 85.6 ng/flea, and d-phenothrin ranging from 14.5 to 130 ng/flea. A comparison with earlier data for permethrin and deltamethrin implied a level of pyrethroid resistance in all isolates and strains. LD50 values for tetrachlorvinphos ranged from 20.0 to 420.0 ng/flea. The rdl mutation (conferring target-site resistance to cyclodiene insecticides) was present in most field-collected and laboratory strains, but had no discernible effect on responses to fipronil, which acts on the same receptor protein as cyclodienes. The kdr and skdr mutations conferring target-site resistance to pyrethroids but segregated in opposition to one another, precluding the formation of genotypes homozygous for both mutations.Peer reviewedFinal Published versio
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