Composite LnNiO3+PrOx oxygen electrodes for solid oxide cells

Ln2NiO4+δ and its derivatives with perovskite-related K2NiF4-type structure demonstrate high mixed ionic-electronic conductivity, moderate thermal and negligible chemical expansion. As a result, these phases attracted significant attention as prospective cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFC). At the same time, perovskite-like LnNiO3 has not been considered for these applications, mostly due to the limited phase stability under ambient oxygen pressures. On heating in air, LaNiO3 decomposes at ~ 1000°C; cathodic polarization can be expected to induce the decomposition of perovskite phase at lower temperatures characteristic for IT-SOFC operation. On the contrary, redox changes imposed by anodic polarization (in solid oxide electrolysis cell mode) under oxidizing conditions should not be of risk for the phase stability of LaNiO3. The goal of the present work was the evaluation of LnNiO3-based oxygen electrodes for solid oxide fuel/electrolysis cells. The LnNiO3-δ ceramic powders with perovskite-like structure was prepared by glycine-nitrate combustion synthesis followed by calcinations in oxygen atmosphere at 800-1000°C. Porous ceramic samples for electrical and dilatometric studies were sintered in oxygen at 950-1050°C. Porous LaNiO3-δ samples were found to exhibit favorably high p-type metallic-like electrical conductivity, 400-500 S/cm at 800-600°C in air. These ceramics demonstrated also a moderate thermal expansion, with average CTE ~ 13.0 ppm/K at 25-800°C, ensuring thermomechanical compatibility with solid electrolytes. As a first step, the electrochemical performance of LaNiO3-δ electrodes was assessed in contact with three common electrolytes including (ZrO2)0.92(Y2O3)0.08 (8YSZ), Ce0.9Gd0.1O2-δ (CGO10) and (La0.8Sr0.2)0.98Ga0.8Mg0.2O3-δ (LSGM). The electrode layers were sintered at 1050°C for 2 h under oxygen flow. The studies of symmetrical cells by EIS demonstrated that the electrochemical activity of LaNiO3-δ electrodes increases in the sequence 8YSZ < CGO10 < LSGM; the corresponding values of electrode polarization resistance (Rη) at 800°C were 1.4, 0.8 and 0.25 Ohm×cm2, respectively. Significant variations of Rη with electrolyte composition correlate with the extent of chemical reactivity between LaNiO3-δ and electrolyte materials during the electrode fabrication. The Rη values of LaNiO3-δ electrodes in contact with LSGM electrolyte were further reduced to 0.03 Ohm×cm2 at 800°C and 0.11 Ohm×cm2 at 700°C by the surface modification with PrOx which is known for its electrocatalytic activity. At 750°C and current density of 0.5 A/cm3, LaNiO3+PrOx (~20 wt.%) electrodes in contact with LSGM solid electrolyte demonstrate the overpotentials of ~60 mV under cathodic polarization and ~40 mV under anodic polarization (Fig.1). The impact of substitution of lanthanum by praseodymium (in order to improve the chemical compatibility and electrochemical activity) on the relevant properties of LnNiO3 is briefly discussed.publishe

Perovskite-like LaNiO3-δ as oxygen electrode material for solid oxide electrolysis cells

Perovskite-like LaNiO3-δ was evaluated as potential oxygen electrode material for solid oxide electrolysis cells. Compared to the Ruddlesden-Popper Lan+1NinO3n+1 (n = 1,2,3) counterparts, LaNiO3-δ exhibits higher p-type metallic-like conductivity under oxidizing conditions (450 S×cm-1 at 800°C for highly porous ceramics) together with a moderate thermal expansion coefficient (13.7 ppm×K-1 in air at 25-800°C) compatible with common solid electrolytes. The measured electrode polarization resistance (Rη) in contact with YSZ, CGO and LSGM solid electrolytes was 1.4, 0.77 and 0.22 Ω×cm2 at 800°C, and 208, 123 and 7.1 Ω×cm2 at 600°C, respectively, under zero-current conditions in air. Surface modification of via PrOx infiltration resulted in lower values of Rη (0.024 Ω×cm2 at 800°C and 0.76 Ω×cm2 at 600°C) and low anodic overpotentials (20 mV at 800°C and 500 mA×cm-2) in contact with LSGM.publishe

Adult-onset autoimmune diabetes: comparative analysis of classical and latent presentation

Introduction: Adult-onset autoimmune diabetes (AID) has two different phenotypes: classic type 1 diabetes mellitus (T1DM), with insulin requirement just after diagnosis, and latent autoimmune diabetes in adults (LADA). The purpose of this study is to characterize patients with AID followed on a tertiary centre, comparing classic T1DM and LADA. Methods: We collected data from patients with diabetes and positive islet autoantibodies, aged 30 years old and over at diagnosis. Patients who started insulin in the first 6 months were classified as T1DM and patients with no insulin requirements in the first 6 months were classified as LADA. Data regarding clinical presentation, autoantibodies, A1C and C-peptide at diagnosis, pharmacologic treatment and complications were analysed. Results: We included 92 patients, 46 with classic T1DM and 46 with LADA. The percentage of females was 50% in T1DM group and 52.1% in LADA group. The median age at diagnosis was 38 years (IQR–15) for T1DM and 42 years (IQR–15) for LADA (p = 0.057). The median time between diagnosis of diabetes and diagnosis of autoimmune aetiology was 0 months in T1DM group and 60 months in LADA group (p < 0.001). The mean BMI at diagnosis was 24.1 kg/m2 in T1DM group and 26.1 kg/m2 in LADA group (p = 0.042). In T1DM group, 67.4% of the patients had more than one positive autoantibody, comparing to 41.3% of LADA patients (p = 0.012). There was no statistical difference in what concerns to title of GAD autoantibodies, A1C and C-peptide at diagnosis of autoimmune aetiology. The presence of symptoms at diagnosis was associated with T1DM group (p < 0.001). The median daily insulin dose was 40 IU for T1DM (0.58 IU/kg) and 33.5 IU for LADA (0.57 IU/kg), with no statistical difference. LADA patients were more often under non-insulin antidiabetic drugs (p = 0.001). At 10 years follow up, 21.1% of T1DM patients and 63.3% of LADA patients had microvascular complications (p = 0.004). Diabetic nephropathy was present in 23.5% of T1DM patients and 53.3% of LADA patients (p = 0.047). At the last evaluation, 55.6% of T1DM and 82.6% of LADA patients had metabolic syndrome and this difference was independent of diabetes duration. Conclusion: Patients with classic T1DM presented more often with symptoms, lower BMI and higher number of autoantibodies, which may be related to a more aggressive autoimmune process. Patients with LADA developed more frequently microvascular complications for the same disease duration, namely diabetic nephropathy, and had more often metabolic syndrome

Mixed Ionic-Electronic Conductivity, Redox Behavior and Thermochemical Expansion of Mn-Substituted 5YSZ as an Interlayer Material for Reversible Solid Oxide Cells

Manganese-substituted 5 mol.% yttria-stabilized zirconia (5YSZ) was explored as a prospective material for protective interlayers between electrolyte and oxygen electrodes in reversible solid oxide fuel/electrolysis cells. [(ZrO2)0.95(Y2O3)0.05]1−x[MnOy]x (x = 0.05, 0.10 and 0.15) ceramics with cubic fluorite structure were sintered in air at 1600 °C. The characterization included X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), thermogravimetry and dilatometry in controlled atmospheres, electrical conductivity measurements, and determination of oxygen-ion transference numbers by the electromotive force (EMF) technique. Mn-substituted 5YSZ solid solutions exhibit variable oxygen nonstoichiometry with manganese cations in a mixed 2+/3+ oxidation state under oxidizing conditions. Substitution by manganese gradually increases the extent of oxygen content variation on thermal/redox cycling, chemical contribution to thermal expansion and dimensional changes on reduction. It also deteriorates oxygen-ionic conductivity and improves p-type electronic conductivity under oxidizing conditions, leading to a gradual transformation from predominantly ionic to prevailing electronic transport with increasing x. Mn2+/3+→Mn2+ transformation under reducing atmospheres is accompanied by the suppression of electronic transport and an increase in ionic conductivity. All Mn-substituted 5YSZ ceramics are solid electrolytes under reducing conditions. Prolonged treatments in reducing atmospheres, however, promote microstructural changes at the surface of bulk ceramics and Mn exsolution. Mn-substituted 5YSZ with 0.05 ≤ x < 0.10 is considered the most suitable for the interlayer application, due to the best combination of relevant factors, including oxygen content variations, levels of ionic/electronic conductivity and thermochemical expansion

O valor das estratégias aumentativas e alternativas de comunicação para os adultos com afasia de Broca: uma revisão narrativa da literatura

Introduction: People with Broca’s aphasia have the right to language recovery and to communicate effectively. No literature review was found about the specific value of augmentative and alternative communication strategies to adults with Broca's aphasia.&nbsp;Aims: To explore current knowledge and update the understanding of the usefulness of augmentative and alternative communication strategies for adults with Broca’s aphasia.&nbsp;Material and method: A narrative literature review was developed based on the research question: What is the usefulness of augmentative and alternative communication for adults with Broca's aphasia? The research was carried out in the CINAHL and MEDLINE databases between January 8 and 21, 2021.&nbsp;Results: 16 articles were included, published between 2011 and 2020. Specific augmentative and alternative communication approaches (no-tech, low-tech, and high-tech), advantages, and factors that influence the effectiveness of this communication support were also identified. This review evidence that augmentative and alternative communication (mainly high-tech) is efficient in optimizing communication and in the language recovery of people with Broca’s aphasia.&nbsp;Conclusions: Augmentative and alternative communication should be employed in adults with Boca’s aphasia with two main aims: compensatory and restorative. High-technology strategies have a particularly positive impact.Introdução: A afasia de Broca é um distúrbio da linguagem e o déficit mais significativo ocorre na comunicação oral, com um discurso não fluente. Esta condição clínica é uma experiência subjetiva devastadora, que tem um impacto marcante na vida pessoal, familiar e social e, consequentemente, na qualidade de vida. As pessoas com afasia de Broca têm direito à recuperação da linguagem e a comunicarem efetivamente. Utilizar estratégias compensatórias ou alternativas à fala natural é especialmente importante para pessoas com afasia de Broca. Tal irá, inerentemente, minimizar o sofrimento associado à comunicação comprometida. Não foi encontrada nenhuma revisão da literatura sobre a importância específica das estratégias de comunicação aumentativa e alternativa para os adultos com afasia de Broca. Objetivos: Explorar o conhecimento atual e atualizar a compreensão sobre a utilidade das estratégias de comunicação aumentativa e alternativa para os adultos com afasia de Broca. Material e método: Foi desenvolvida uma revisão narrativa da literatura com base na questão de pesquisa: Qual a utilidade da comunicação aumentativa e alternativa para os adultos com afasia de Broca? A pesquisa foi realizada nas bases de dados CINAHL e MEDLINE entre os dias 8 e 21 de janeiro de 2021. Resultados: Foram incluídos 15 artigos, publicados entre 2011 e 2020. Foram identificadas abordagens específicas de comunicação aumentativa e alternativa (sem tecnologia, baixa tecnologia e alta tecnologia), vantagens e também fatores que influenciam a eficácia destes suportes de comunicação. Esta revisão evidencia que a comunicação aumentativa e alternativa (principalmente de alta tecnologia) é eficiente na otimização da comunicação e na recuperação da linguagem de pessoas com afasia de Broca. Conclusões: A comunicação aumentativa e alternativa deve ser utilizada em adultos com afasia de Boca com dois objetivos principais: compensatório e restaurador. As estratégias de alta tecnologia têm um impacto particularmente positivo

Biossolubilização de fonolito por microrganismos do solo solubilizadores de potássio.

A produção nacional de fertilizantes potássicos atende somente 10% da demanda do agronegócio brasileiro. Como os solos brasileiros, em geral, possuem baixa fertilidade, verifica-se a necessidade de pesquisas visando novas fontes deste nutriente para a produção agrícola. Neste estudo, procurou-se avaliar o potencial de diferentes estirpes de microrganismos pertencentes à coleção de Microrganismos Multifuncionais da Embrapa Milho e Sorgo quanto à biossolubilização de potássio a partir da rocha fonolito in vitro. Testaram-se 13 isolados, sendo três bactérias e dez fungos quanto à taxa de solubilização em meio de cultura líquido, após 10 dias de agitação, sob temperatura de 28°C. Os teores de potássio foram determinados nos sobrenadantes das culturas enriquecidas após a filtração. Os resultados mostraram que a biodisponibilidade de potássio nos meios de cultura variaram significativamente em função dos isolados. A bactéria B30 foi a estirpe mais eficiente na solubilização de K, com incremento de 70% de solubilização, em relação ao controle não inoculado. Observou-se uma correlação negativa entre os valores do pH no meio de cultura e taxa de solubilização das estirpes. Estes resultados sugerem que os microrganismos avaliados podem ser utilizados para otimizar a biodisponibilidade de potássio a partir de rochas silicáticas

Biossolublização de fosfatos naturais e crescimento de milheto (Pennisetum americanum).

O setor agrícola no país vem ganhando espaço devido sua contribuição ao desenvolvimento econômico nacional. Porém, grande parte dos solos brasileiros possui baixa disponibilidade de fósforo (P), acabando por limitar este crescimento e gerando uma dependência elevada de fertilizantes fosfatados, em sua maioria importados. Este fato justifica estudos para uso de fontes alternativas de fósforo, como os fosfatos naturais de rocha. Neste trabalho, buscou-se avaliar a liberação de P por microrganismos a partir de fosfatos de Araxá e de Itafós, em dois cultivos consecutivos de milheto em casa de vegetação. Foram conduzidos dois ensaios, utilizando-se duas bactérias previamente selecionadas como biossolubilizadoras de P in vitro (CMMSB70 e CMMSB30), sendo um com inoculante bioprocessado e outro com rochas não-bioprocessado, no total de 12 tratamentos cada, duas estirpes de bactérias combinadas com três fontes de P (duas rochas e supertriplo), além de tratamentos controle (fontes de P sem bactéria; sem rocha sem bactérias). Os tratamentos foram dispostos em delineamento inteiramente casualizado, com quatro repetições. Após a coleta em cada cultivo, avaliou-se a produção de massa seca da parte aérea na fase de pré-florescimento. No segundo cultivo, houve ganho de cerca de 20% de massa seca para o tratamento de Rocha Araxá e Itafós com inoculação de B32 e B70 respectivamente, com relação ao tratamento com a rocha, sem microrganismos. De acordo com os resultados obtidos, pode-se, de forma preliminar, inferir que a adição de microrganismos selecionados pode agregar valor aos fertilizantes fosfatos de rocha

PrOx-infiltrated LnNiO3-based oxygen electrodes for solid oxide cells

Ln2NiO4+δ and its derivatives with perovskite-related K2NiF4-type structure demonstrate high mixed ionic-electronic conductivity, moderate thermal and negligible chemical expansion. As a result, these phases attracted significant attention as prospective cathode materials for intermediatetemperature solid oxide fuel cells (IT-SOFC). At the same time, perovskite-like LnNiO3 have not been considered for these applications, mostly due to the limited phase stability under ambient oxygen pressures. On heating in air, LaNiO3 decomposes at ~ 1000°C; cathodic polarization can be expected to induce the decomposition of perovskite phase at lower temperatures characteristic for IT-SOFC operation. On the contrary, redox changes imposed by anodic polarization (in solid oxide electrolysis cell mode) under oxidizing conditions should not be of risk for the phase stability of LaNiO3. The goal of the present work was the evaluation of LnNiO3-based oxygen electrodes for solid oxide fuel/electrolysis cells. The LnNiO3-δ ceramic powders with perovskite-like structure was prepared by glycine-nitrate combustion synthesis followed by calcinations in oxygen atmosphere at 800-1000°C. Porous ceramic samples for electrical and dilatometric studies were sintered in oxygen at 950-1050°C. Porous LaNiO3-δ samples were found to exhibit favorably high p-type metallic-like electrical conductivity, 400-500 S/cm at 800-600°C in air. These ceramics demonstrated also a moderate thermal expansion, with average CTE ~ 13.0 ppm/K at 25-800°C, ensuring thermomechanical compatibility with solid electrolytes. As a first step, the electrochemical performance of LaNiO3-δ electrodes was assessed in contact with three common electrolytes including (ZrO2)0.92(Y2O3)0.08 (8YSZ), Ce0.9Gd0.1O2-δ (CGO10) and (La0.8Sr0.2)0.98Ga0.8Mg0.2O3-δ (LSGM). The electrode layers were sintered at 1050°C for 2 h under oxygen flow. The studies of symmetrical cells by EIS demonstrated that the electrochemical activity of LaNiO3-δ electrodes increases in the sequence 8YSZ < CGO10 < LSGM; the corresponding values of electrode polarization resistance (Rη) at 800°C were 1.4, 0.8 and 0.25 Ohm×cm2 , respectively. Significant variations of Rη with electrolyte composition correlate with the extent of chemical reactivity between LaNiO3-δ and electrolyte materials during the electrode fabrication. The Rη values of LaNiO3-δ electrodes in contact with LSGM electrolyte were further reduced to 0.03 Ohm×cm2 at 800°C and 0.11 Ohm×cm2 at 700°C by the surface modification with PrOx which is known for its electrocatalytic activity. At 750°C and current density of 0.5 A/cm2 , LaNiO3+PrOx (~20 wt.%) electrodes in contact with LSGM solid electrolyte demonstrate the overpotentials of ~60 mV under cathodic polarization and ~40 mV under anodic polarization. The impact of substitution of lanthanum by praseodymium (in order to improve the chemical compatibility and electrochemical activity) on the relevant properties of LnNiO3 is briefly discussed.publishe

Oxygen Therapy in Advanced Disease: Do You Know the Evidence?

A dispneia é um dos sintomas que tem mais impacto tanto para o doente com doença avançada, como para o profissional de saúde com a responsabilidade de o acompanhar. Sem prejuízo de se dever aprofundar a evidência disponível sobre as indicações e eficácia da oxigenoterapia, é já vasta a informação que suporta a evidência de que o uso de oxigénio com intenção paliativa deve ser prescrito de forma criteriosa pois, à semelhança de qualquer outro tratamento, tem efeitos secundários associados e pode causar malefícios. O artigo que se apresenta é uma revisão bibliográfica das mais recentes matérias publicadas neste âmbito, com o objetivo de contribuir para melhorar a prática clínica no contexto do tratamento dos doentes em fim de vida.info:eu-repo/semantics/publishedVersio