2,313 research outputs found
Metals recovery from spent Zn-MnO2 batteries by Hydrometallurgy
A hydrometallurgical process for recycling spent Zn-MnO2 batteries was developed, involving leaching with sulfuric acid, purification by precipitation and metals separation for further recovery. Leaching of zinc oxide was easily attained while for manganese oxide was rather difficult depending on temperature and acid concentration. At 90ÂșC and with the liquid/solid ratio of 20 L/kg, more than 95% of zinc is recovered in 30 minutes with 0.5M H2SO4. To attain similar recovery for manganese, higher levels of acid concentration and time are needed (e.g 0.7 M and 2 hours). After leaching a purification step is necessary to remove iron co-dissolved through Fe(III) precipitation. Separation of zinc from manganese by solvent extraction with 1M DEHPA follows in the process route. The countercurrent multistage separation diagram developed allows the production of a zinc electrolyte with 120 g/L Zn and 0.005 g/L Mn, and a raffinate with 16 g/L Mn and 0.013 g/L Zn
Otite MĂ©dia Aguda no Pequeno Lactente
Introdução: A otite média aguda (OMA) é uma patologia comum na infùncia mas rara
abaixo dos 3 meses de idade
Objectivos: Caracterizar a OMA e avaliar eventuais factores de risco no pequeno
lactente.
MĂ©todos: Estudo descritivo, de 2005 a 2009 em lactentes com menos de trĂȘs meses,
internados por OMA. Analisaram-se idade, sexo, factores de risco (FR) comorbilidades,
clĂnica, terapĂȘutica e evolução. A avaliação de factores de risco foi realizada com grupo
de controlo emparelhado para a idade.
Resultados: Registaram-se 58 casos (18 recém-nascidos) com mediana de idades de 30
dias. Em 50 (86,2%) casos havia pelo menos um factor de risco: leite para lactentes
exclusivo (31), agregado familiar com um irmĂŁo (31), uso de chupeta (18), atopia
familiar (14), pai fumador (12), regurgitação frequente (11), mãe fumadora (10), refluxo gastroesofågico (5) e prematuridade (4). Trinta e quatro crianças (58,6%) tinham dois ou mais FR.
Registaram-se infecçÔes virais prévias em 38 doentes e nenhum caso cursou com
bacteriĂ©mia ou doença invasiva. A mediana do valor dos leucĂłcitos foi 10960/ÎŒL e a
proteĂna C reactiva (PCR) 0,44 mg/dL. Todos fizeram antibioticoterapia endovenosa, a
maioria (69%) com ampicilina e gentamicina (mediana de 7 dias).
Foram FR para a ocorrĂȘncia de otite ter pelo menos um irmĂŁo (p<0,00; OR=0,033; IC
95% 0,006-0,179), a mĂŁe ser fumadora (p<0,019; OR 0,125; IC 95% 0,022-0,715) e
prematuridade (p<0,009; OR 1,047; IC 95% 1,011-1,084). O sexo masculino (p=0,698),
baixo peso (p=0,548), leite para lactentes exclusivo (p=0,301), uso de chupeta
(p=0,101), regurgitação (p=0,646), refluxo gastro-esofågico p=0,594), atopia familiar
(p=0,651) e pai fumador (p=0,609) nĂŁo foram estatisticamente significativos para OMA.
Foram contactados 30/58 crianças registando-se otites recorrentes em 15 (50%) com
associação estatisticamente significativa entre a recorrĂȘncia de OMA e o sexo
masculino (43,3%vs6,7%, p=0,03).
ComentĂĄrios: A OMA no pequeno lactente cursa habitualmente sem repercussĂŁo sistĂ©mica pelo que a terapĂȘutica endovenosa provavelmente sĂł serĂĄ necessĂĄria no recĂ©m-nascido dada a imaturidade farmacocinĂ©tica deste grupo etĂĄrio.
A presença de pelo menos um irmão no agregado familiar, a prematuridade e mãe ser
fumadora foram neste estudo factores de risco para a ocorrĂȘncia de OMA e o sexo
masculino para a recorrĂȘncia
Acute Otitis Media in Infants Less than Three Months
Introdução: A otite mĂ©dia aguda (OMA) Ă© uma das patologias infecciosas bacterianas mais comuns na infĂąncia, mas rara abaixo dos trĂȘs meses de idade e ainda pouco estudada neste grupo etĂĄrio.
Objectivos: Descrever os casos de OMA em lactentes com idade inferior a trĂȘs meses e avaliar a importĂąncia de potenciais
factores de risco no aparecimento de doença assim como na sua recorrĂȘncia.
MĂ©todos: Estudo observacional descritivo retrospectivo de lactentes com menos de trĂȘs meses internados por OMA entre 2005 e 2009. Avaliação de eventuais factores de risco para a ocorrĂȘncia e recorrĂȘncia de OMA atravĂ©s de estudo analĂtico longitudinal retrospectivo de caso-controlo.
Resultados: Registaram-se 58 casos (18 recĂ©m-nascidos) com mediana de idades de 30 dias. Todos foram submetidos a terapĂȘutica
antibiótica endovenosa (mediana de sete dias), mas não se registaram casos de doença invasiva. Registou-se em 86,2% dos casos (50/58) pelo menos um factor de risco: fórmula para lactentes exclusiva (31/58, 53,4%), agregado familiar com pelo
menos um irmĂŁo (31/58, 53,4%), uso de chupeta (18/58, 31%), atopia familiar (14/58, 24,1%), pai fumador (12/58, 20,7%),
regurgitação frequente (11/58, 19%), mĂŁe fumadora (10/58, 17,2%), refluxo gastroesofĂĄgico (5/58, 8,6%), baixo peso (5/58, 8,6%) e prematuridade (4/58, 6,9%). Contudo, aqueles em que se encontrou significĂąncia estatĂstica (por regressĂŁo logĂstica) foram: prematuridade p<0,009;OR=1,047; IC95%), mĂŁe
fumadora (p<0,019;OR=0,125;IC95%) e agregado familiar com pelo menos um irmĂŁo (p<0,00;OR=0,033;IC95%). Registaram- se otites recorrentes em 15/30 (50%) lactentes, mais frequentemente no sexo masculino (43,3%vs6,7%, p=0,038).
ConclusĂ”es: Em lactentes com idade inferior a trĂȘs meses, a prematuridade, mĂŁe fumadora e presença de um agregado familiar com pelo menos um irmĂŁo constituem factores de risco para a ocorrĂȘncia de OMA, sendo a sua recorrĂȘncia mais frequente no sexo masculino
Biodiversity of prokaryotes from high-elevation grassland organosols of the Parana State, Brazil.
Sheared Poliodal Flows and Turbulence in the Edge Plasma Region of Stellarator and Tokamak Devices
Enterprise Ionic Liquids Database (ILUAM) for Use in Aspen ONE Programs Suite with COSMO-Based Property Methods
âThis document is the Accepted Manuscript version of a Published Work that appeared in final form in Industrial & Engineering Chemistry Research copyright © American Chemical Society after peer review and technical editing by the publisher . To access the final and published work see Enterprise Ionic Liquids Database (ILUAM) for Use in Aspen ONE Programs Suite with COSMO-Based Property
Methods V. R. Ferro, C. Moya, D. Moreno, R. Santiago, J. de Riva, G. Pedrosa, M. Larriba, I. Diaz, and J. Palomar
Industrial & Engineering Chemistry Research 2018 57 (3), 980-989
DOI: 10.1021/acs.iecr.7b04031An enterprise database of pure ionic liquids (ILs) for its use in the Aspen ONE programs is presented. The database is identified as ILUAM, and the first version (ILUAM01) contains 100 ILs composed of 30 cations and 23 anions. The IL components were introduced in Aspen Properties as pseudocomponents using information from the computational COSMO-RS method and from experimental viscosity data. ILUAM database was created to be used along with the COSMOSAC property model implemented in Aspen Plus, allowing evaluating IL process performance without needing further experimental data. Some validation tests were carried out to demonstrate the successful incorporation of ILs in the Aspen Plus property system. Then, the performance of ILUAM01 database in thermodynamic property predictions of mixtures involving ILs and conventional chemical compounds was revised in terms of activity coefficients at infinite dilution and phase equilibrium data. The property description of pure ILs and IL mixtures with conventional chemical compounds using COSMO-based/Aspen Plus approach was found with the accuracy level required in the conceptual design of new processes. ILUAM database offers the opportunity of performing systematic evaluation of potential industrial applications of ILs and their competitiveness as alternative to conventional solvents.The authors are grateful to the Comunidad de Madrid (project S2013-
MAE-2800) and to the Ministerio de EconomĂa y Competitividad of Spain (Project CTQ2014-52288-R) for financial support. M. Larriba also thanks Ministerio de EconomĂa y Competitividad of Spain for awarding him a Juan de la Cierva-FormaciĂłn Contract (Reference FJCI-2015-25343
Exact exchange-correlation potential for a time-dependent two electron system
We obtain an exact solution of the time-dependent Schroedinger equation for a
two-electron system confined to a plane by an isotropic parabolic potential
whose curvature is periodically modulated in time. From this solution we
compute the exact time-dependent exchange correlation potential v_xc which
enters the Kohn-Sham equation of time-dependent density functional theory. Our
exact result provides a benchmark against which various approximate forms for
v_xc can be compared. Finally v_xc is separated in an adiabatic and a pure
dynamical part and it is shown that, for the particular system studied, the
dynamical part is negligible.Comment: 23 pages, 6 figure
Managing affect in learners' questions in undergraduate science
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2012 Society for Research into Higher Education.This article aims to position students' classroom questioning within the literature surrounding affect and its impact on learning. The article consists of two main sections. First, the act of questioning is discussed in order to highlight how affect shapes the process of questioning, and a four-part genesis to question-asking that we call CARE is described: the construction, asking, reception and evaluation of a learner's question. This work is contextualised through studies in science education and through our work with university students in undergraduate chemistry, although conducted in the firm belief that it has more general application. The second section focuses on teaching strategies to encourage and manage learners' questions, based here upon the conviction that university students in this case learn through questioning, and that an inquiry-based environment promotes better learning than a simple âtransmissionâ setting. Seven teaching strategies developed from the authors' work are described, where university teachers âscaffoldâ learning through supporting learners' questions, and working with these to structure and organise the content and the shape of their teaching. The article concludes with a summary of the main issues, highlighting the impact of the affective dimension of learning through questioning, and a discussion of the implications for future research
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