Cement As a Waste Form for Nuclear Fission Products: The Case of 90Sr and Its Daughters

One of the main challenges faced by the nuclear industry is the long-term confinement of nuclear waste. Because it is inexpensive and easy to manufacture, cement is the material of choice to store large volumes of radioactive materials, in particular the low-level medium-lived fission products. It is therefore of utmost importance to assess the chemical and structural stability of cement containing radioactive species. Here, we use ab initio calculations based on density functional theory (DFT) to study the effects of ⁹⁰Sr insertion and decay in C-S-H (calcium-silicate-hydrate) in order to test the ability of cement to trap and hold this radioactive fission product and to investigate the consequences of its β-decay on the cement paste structure. We show that ⁹⁰Sr is stable when it substitutes the Ca²⁺ ions in C-S-H, and so is its daughter nucleus ⁹⁰Y after β-decay. Interestingly, ⁹⁰Zr, daughter of ⁹⁰Y and final product in the decay sequence, is found to be unstable compared to the bulk phase of the element at zero K but stable when compared to the solvated ion in water. Therefore, cement appears as a suitable waste form for ⁹⁰Sr storage.

Dietary Micronutrient Intake and Micronutrient Status in Patients With Chronic Stable Heart Failure: An Observational Study.

BACKGROUND: Observational studies suggest that patients with heart failure have a tendency to a reduced status of a number of micronutrients and that this may be associated with an adverse prognosis. A small number of studies also suggest that patients with heart failure may have reduced dietary intake of micronutrients, a possible mechanism for reduced status.

OBJECTIVE: The aims of this study were to assess dietary micronutrient intake and micronutrient status in a group of patients with heart failure.

METHODS: Dietary intake was assessed in 79 outpatients with chronic stable heart failure with a reduced ejection fraction using a validated food frequency questionnaire. Blood concentrations of a number of micronutrients, including vitamin D, were measured in fasting blood samples, drawn at the time of food frequency questionnaire completion.

RESULTS: More than 20% of patients reported intakes less than the reference nutrient intake or recommended intake for riboflavin, vitamin D, vitamin A, calcium, magnesium, potassium, zinc, copper, selenium, and iodine. More than 5% of patients reported intakes less than the lower reference nutrient intake or minimum recommended intake for riboflavin, vitamin D, vitamin A, calcium, magnesium, potassium, zinc, selenium, and iodine. Vitamin D deficiency (plasma total 25-hydroxy-vitamin D concentration <50 nmol/L) was observed in 75.6% of patients.

CONCLUSIONS: Vitamin D deficiency was common in this group of patients with heart failure. Based on self-reported dietary intake, a substantial number of individuals may not have been consuming enough vitamin D and a modest number of individuals may not have been consuming enough riboflavin, vitamin A, calcium, magnesium, potassium, zinc, copper, selenium, or iodine to meet their dietary needs.

Community dynamics and the lower airway microbiota in stable chronic obstructive pulmonary disease, smokers and healthy non-smokers

RATIONALE: The role bacteria play in the progression of COPD has increasingly been highlighted in recent years. However, the microbial community complexity in the lower airways of patients with COPD is poorly characterised.

OBJECTIVES: To compare the lower airway microbiota in patients with COPD, smokers and non-smokers.

METHODS: Bronchial wash samples from adults with COPD (n=18), smokers with no airways disease (n=8) and healthy individuals (n=11) were analysed by extended-culture and culture-independent Illumina MiSeq sequencing. We determined aerobic and anaerobic microbiota load and evaluated differences in bacteria associated with the three cohorts. Culture-independent analysis was used to determine differences in microbiota between comparison groups including taxonomic richness, diversity, relative abundance, 'core' microbiota and co-occurrence.

MEASUREMENT AND MAIN RESULTS: Extended-culture showed no difference in total load of aerobic and anaerobic bacteria between the three cohorts. Culture-independent analysis revealed that the prevalence of members of Pseudomonas spp. was greater in the lower airways of patients with COPD; however, the majority of the sequence reads for this taxa were attributed to three patients. Furthermore, members of Bacteroidetes, such as Prevotella spp., were observed to be greater in the 'healthy' comparison groups. Community diversity (α and β) was significantly less in COPD compared with healthy groups. Co-occurrence of bacterial taxa and the observation of a putative 'core' community within the lower airways were also observed.

CONCLUSIONS: Microbial community composition in the lower airways of patients with COPD is significantly different to that found in smokers and non-smokers, indicating that a component of the disease is associated with changes in microbiological status.

Tracing coastal organic enrichment: stable isotopes and biotic indices

Neste trabalho foi efectuada uma avaliação integrada usando descritores sedimentares e biológicos ao nível da espécie e da comunidade e índices bióticos de síntese para o traçamento do enriquecimento orgânico numa região, com características dispersivas, da costa Oeste de Portugal. Na área estudada existem gradientes ambientais e biológicos relacionados com a heterogeneidade da paisagem sedimentar, a qual inclui sedimentos desde areias finas limpas a vasas. Contudo, na área próxima do emissário, esta paisagem é mais homogénea e constituída por areia fina com baixo teor em finos. Nesta região, alguns dos descritores estudados deram uma indicação coerente de alterações ambientais associadas ao enriquecimento orgânico. O potencial de oxidação - redução mostrou valores negativos até 250 m do emissário, o que indicia que a degradação da matéria orgânica que entra no sistema cria condições reduzidas no sedimento. Os isótopos estáveis de carbono e azoto no sedimento diferenciam a área mais próxima do emissário, que apresenta uma depleção de acordo com uma origem terrestre da matéria orgânica naquela parte da plataforma. Uma imagem similar foi obtida pela análise dos isótopos estáveis na macrofauna que diagnosticou a origem terrestre da matéria orgânica consumida. A composição específica e a abundância das comunidades bentónicas também são significativamente diferentes junto ao emissário, onde são dominadas por espécies oportunistas, tolerantes ao enriquecimento orgânico. No entanto, os índices bióticos em validação no âmbito da implementação da Directiva Quadro da Água, não foram eficientes a mostrar as alterações bentónicas associadas ao enriquecimento orgânico apesar de alguns índices se basearem nos limiares de tolerância/sensibilidade a este tipo de perturbação. Apesar deste caso de estudo reflectir um enriquecimento orgânico moderado, uma vez que não foram detectadas alterações sedimentares ou acumulação de matéria orgânica, nem um significativo empobrecimento das comunidades biológicas junto ao emissário, a análise ao nível dos índices bióticos de síntese pode levar à perda de informação essencial e, portanto, prejudicar a nossa capacidade de diagnóstico devendo ser usados com cuidado. A análise do conjunto de dados da composição específica forneceu uma imagem mais precisa da perturbação ambiental e descritores específicos, tais como os isótopos estáveis, permitiram uma melhor compreensão da extensão espacial do enriquecimento orgânico.

Híbridos orgânicos-inorgânicos para aplicações de baixo custo em óptica integrada

O objectivo desta tese é a utilização de materiais híbridos orgânicos-inorgânicos, designados por di-ureiasis modificados pela adição de tetra-propóxido de zircónio (Zr(i-OPr)4) estabilizado com ácido metacrílico (CH2=C(CH3)COOH), obtidos pela via sol-gel, para aplicações em dispositivos ópticos integrados de baixo custo. A estrutura local dos di-ureiasis com diferentes concentrações de propóxido de zircónio (20 a 80 % mol) foi estudada por difracção de raios-X, espalhamento de raios X a baixos ângulos, microscopia de força atómica, ressonância magnética nuclear dos núcleos dos átomos de 29Si e 13C, espectroscopia no infravermelho por transformada de Fourier, espectroscopia de Raman por transformada de Fourier e termogravimetria. A influência dos parâmetros de síntese, concentração de tetra propóxido de zircónio e rácio tetra propóxido de zircónio: ácido metacrilico na estrutura e propriedades das amostras em monólito e filmes finos (depositados pela técnica de deposição por rotação do substrato) foram avaliadas, permitindo obter amostras transparentes, fotopolimerizáveis e estáveis termicamente até aos 100 ºC. Foram determinadas as propriedades dos guias planares em substratos de vidro borosilicato e silício oxidado (1

Stable standard essential for prosperity. Speech in the Senate of the United States, February 4, 1878

This speech was given when the United States Senate was considering a bill to authorize the free coinage of the standard silver dollar and to restore its legal tender character. Mr. Bayard argues against the bill in this speech. He is interrupted during his speech multiple times and questioned about his points.

The Personal and Professional Selves of Teachers: Stable and Unstable Identities

In much educational literature it is recognised that the broader social conditions in which teachers live and work, and the personal and professional elements of teachers' lives, experiences, beliefs and practices are integral to one another, and that there are often tensions between these which impact to a greater or lesser extent upon teachers' sense of self or identity. If identity is a key influencing factor on teachers' sense of purpose, self‐efficacy, motivation, commitment, job satisfaction and effectiveness, then investigation of those factors which influence positively and negatively, the contexts in which these occur and the consequences for practice, is essential. Surprisingly, although notions of ‘self’ and personal identity are much used in educational research and theory, critical engagement with individual teachers' cognitive and emotional ‘selves’ has been relatively rare. Yet such engagement is important to all with an interest in raising and sustaining standards of teaching, particularly in centralist reform contexts which threaten to destabilise long‐held beliefs and practices. This article addresses the issue of teacher identities by drawing together research which examines the nature of the relationships between social structures and individual agency; between notions of a socially constructed, and therefore contingent and ever‐remade, ‘self’, and a ‘self’ with dispositions, attitudes and behavioural responses which are durable and relatively stable; and between cognitive and emotional identities. Drawing upon existing research literature and findings from a four‐year Department for Education and Skills funded project with 300 teachers in 100 schools which investigated variations in teachers' work and lives and their effects on pupils (VITAE), it finds that identities are neither intrinsically stable nor intrinsically fragmented, as earlier literature suggests. Rather, teacher identities may be more, or less, stable and more or less fragmented at different times and in different ways according to a number of life, career and situational factors.

Avaliação do potencial clínico de novos ligandos para o receptor estrogénico em diagnóstico e terapia de tumores da mama

Tese de doutoramento, Química (Química Inorgânica), Universidade de Lisboa, Faculdade de Ciências, 2015

Tropical paleoclimate reconstructions from stable isotopes of mangrove lipid biomarkers

Thesis (Ph.D.)--University of Washington, 2014

Study the function of the newly discovered TrkB receptor fragment (TrkB-ICD) formed by calpain cleavage

Tese de mestrado, Neurociências, Faculdade de Medicina, Universidade de Lisboa, 2016