Probing stress and fracture mechanism in encapsulated thin silicon solar cells by synchrotron X-ray microdiffraction

Thin (<150 µm) silicon solar cell technology is attractive due to the significant cost reduction associated with it. Consequently, fracture mechanisms in the thin silicon solar cells during soldering and lamination need to be fully understood quantitatively in order to enable photovoltaics (PV) systems implementation in both manufacturing and field operations. Synchrotron X-ray Microdiffraction (µSXRD) has proven to be a very effective means to quantitatively probe the mechanical stress which is the driving force of the fracture mechanisms (initiation, propagation, and propensity) in the thin silicon solar cells, especially when they are already encapsulated. In this article, we present the first ever stress examination in encapsulated thin silicon solar cells and show how nominally the same silicon solar cells encapsulated by different polymer encapsulants could have very different residual stresses after the lamination process. It is then not difficult to see how the earlier observation, as reported by Sander et al. (2013) [1], of very different fracture rates within the same silicon solar cells encapsulated by different Ethylene Vinyl Acetate (EVA) materials could come about. The complete second degree tensor components of the residual stress of the silicon solar cells after lamination process are also reported in this paper signifying the full and unique capabilities of the Synchrotron X-Ray Microdiffraction technique not only for measuring residual stress but also for measuring other potential mechanical damage within thin silicon solar cells

The prognostic value of plasma fi brinogen concentrations of patients with ST-elevation myocardial infarction and treated by primary percutaneous coronary intervention : A cautionary message

Background. Fibrinogen elevation is associated with a worse prognosis in patients with acute coronary syndrome (ACS). The aim of the present study was to assess the prognostic value of increased fi brinogen concentrations in ST-elevation myocardial infarction (STEMI) patients treated with primary percutaneous coronary intervention (PCI). Methods. A total of 428 STEMI patients treated with primary PCI were retrospectively selected (median age: 62 years; 82.5% males) from a continuous case series of 832 ACS patients. Plasma fi brinogen concentrations were measured before PCI and after 24, 48, and 72 hours. In the 4-year follow-up, one major adverse cardiovascular event (MACE) occurred in 111 patients (40%): 17 re-STEMI (7%), 64 re-PCI (22%), 22 cardiac deaths (7%), and eight non ST-elevated acute coronary syndromes (NSTEACS, 4%). Results. According to the reference change value, fi brinogen concentrations increased in 25% of patients at 24 h, 64% at 48 h and 19% at 72 h. Only fi brinogen concentrations at 48 h showed a mild association with overall MACEs ( p 0.036): the risk increased, starting from a concentration of 4 g/L. However a further multivariate model did not confi rm any prognostic value. No association with specifi c MACEs emerged. Conclusions. In contrast to NSTEACS patients, fi brinogen concentrations increased slightly in STEMI patients after primary PCI, however, they were not as prognostic as for MACEs

Níveis séricos de hemoglobina em adolescentes segundo estágio de maturação sexual Hemoglobin serum levels in adolescents according to sexual maturation stage

A adolescência constitui etapa de risco para o desenvolvimento da anemia ferropriva, uma vez que ocorre aumento da necessidade de ferro decorrente do crescimento estatural e da maturação biológica. Estudaram-se 130 adolescentes, de ambos os sexos, para verificar os valores de hemoglobina sérica em diferentes fases de maturação sexual. Utilizou-se o método de fotometria para dosar a hemoglobina sérica e realizou-se auto-avaliação do estágio de maturação sexual com base nos critérios de Tanner. Os níveis médios de hemoglobina foram semelhantes entre sexos, bem como entre meninas que menstruavam ou não. O nível médio de hemoglobina foi de 13,3g/dL tanto para os meninos como para as meninas (p=0,64), com desvios-padrão de 1,12 e de 0,83, respectivamente. Entre os adolescentes estudados, 7,7% tinham anemia ferropriva. Recomenda-se atenção ao grupo de adolescentes, devido ao aumento da necessidade de ferro durante o estirão de crescimento, principalmente entre as meninas, aumentando a suscetibilidade à anemia.<br>During adolescence, the risk of development of iron-deficiency anemia is higher because of the growth spurt and the sexual maturation which increase the iron requirement. One hundred and thirty adolescents (males and females) were studied, in order to assess the serum hemoglobin values in different sexual maturation stages. The photometric method was used and a self-evaluation of the sexual maturation stage based on Tanner's criteria was applied. The average hemoglobin values were similar for both sexes, as well for girls who had menstruated or not. The average hemoglobin values were 13.3 (s.d. 1.12)g/dL for males and 13.3 (s.d. 0.83)g/dL for females (p=0.64). Among the studied adolescents, 7.7% had iron-deficiency anemia. Due to the iron requirement increase during the growth spurt, mainly in females, and the higher susceptibility to iron deficiency anemia, special attention to the adolescents is recommended

Estudo comparativo da pressão arterial e da prevalência de hipertensão arterial em duas coortes sucessivas (1975-1976) de estudantes de 16 a 25 anos, Botucatu, SP, Brasil Blood pressure levels and hipertension prevalence in 16 to 25 year-old students in Botucatu, S. Paulo, Brazil. A comparative study of two successive cohorts, 1975-1976

Com o objetivo de determinar os níveis de pressão arterial e a prevalência de hipertensão arterial em uma população jovem, foram realizados pesquisas em dois anos sucessivos em 1.288 e 736 estudantes de Botucatu, SP (Brasil) tendo sido comparados os resultados obtidos. As médias das pressões sistólicas da população estudada e dos dois grupos etários desta população (16 a 20 anos e 21 a 25 anos) foram idênticas em ambos os anos, tendo as médias das pressões diastólicas diferido de no máximo 2 mmHg; as médias, tanto sistólicas quanto diastólicas, dos dois sexos e da parcela branca da população estudada quanto à idade e sexo também diferiram de no máximo 2 mmHg. As médias da população estudada e sua parcela branca, em ambos os anos, foram superiores no sexo masculino e no grupo etário de 21 a 25 anos. Na população negra e amarela houve disparidade de resultados entre 1975 e 1976, indicando influência da exiguidade do tamanho dos contigentes negro e amarelo desta população. A prevalência de hipertensão arterial (pressão sistólica igual ou maior que 140 mmHg e diastólica igual ou maior que 90 mmHg) foi de 5,04% em 1975 e 6,22% em 1976, tendo sido em ambos os anos maior no sexo masculino do que no feminino e no grupo de 21 a 25 do que no de 16 a 20 anos.<br>To determine the prevalence of hypertension and blood pressure levels in a young population group, two groups, one of 1288 students and another of 736, all from Botucatu, were investigated during two consecutive years, and the results were then compared. The mean values for systolic readings of the whole population, as for the two age groups (16 to 20 and 21 to 25 years old), were identical for both years studied; the diastolic mean values differed by 2 mmHg at most. The mean systolic and diastolic reading for both sexes and among the whites also differed by 2 mmHg at most. The mean values for the whole population and among the white population were higher for males than for females, and also higher in the 21 to 25 age group than in the 16 to 20 group. The 1975 and 1976 results for the black and yellow population were inconsistent, reflecting the influence of the small size of these groups. The prevalence of arterial hypertension (systolic readings equal to or higher than 140 mmHg and diastolic readings equal to or higher than 90 mmHg) was 5.04% in 1975 and 6.22% in 1976, being higher in the males than in the females and higher in the 21 to 25 age group than in the 16 to 20 year-old group

Feeding ecology of Tropidurus torquatus (Wied) (Squamata, Tropiduridae) in two areas with different degrees of conservation in Marambaia Island, Rio de Janeiro, Southeastern Brazil

We compared the effects of habitat disturbance on the feeding ecology of two local populations of Tropidurus torquatus (Wied, 1820) in restinga habitats on Ilha da Marambaia, Southeastern Brazil. Both populations presented a relatively diverse diet and differ in the number (D Max = 0.22, DF = 2, p = 0.00) and volume of prey consumed (D Max = 0.82, DF = 2, p = 0.00). Ants were the most frequent and numerous preys in both areas, and plant matter and coleopterans were the most important alimentary items in volume. The population from the disturbed area presented a larger niche breadth for number of prey items consumed (Bi num = 3.06) and volume (Bi vol = 2.98), when compared to the other population (Bj num = 2.44, Bj vol = 1.52). Niche overlap was higher for number of items consumed between the populations (Oij num = 0.82) but lower for volume (Oij vol = 0.05). Our data suggest dietary differences between the two lizard populations, and these differences may be associated with environmental modifications. Our main hypothesis to explain the dietary differences is based in the Optimal Foraging Theory. However, the alimentary behavior, and consequently the diet of these lizards, seems to be constrained phylogenetically, with a pattern that may have evolved in the ancestor of all iguanids.<br>Comparamos os efeitos da degradação ambiental sobre a ecologia alimentar de duas populações de Tropidurus torquatus (Wied, 1820) em áreas de restinga da Ilha da Marambaia, sudeste do Brasil. Ambas as populações apresentaram dieta relativamente diversa e deferiram em número (D Max = 0,22; DF = 2; p = 0,00) e volume de presas consumidas (D Max = 0,82; DF = 2; p = 0,00). Formigas foram os itens mais freqüentes e numerosos em ambas as áreas, e material vegetal e coleópteros os mais importantes em volume. A população da área perturbada apresentou maior largura de nicho alimentar para número de presas consumidas (Bi num = 3,06) e volume (Bi vol = 2,98), quando comparada à outra população (Bj num = 2,44; Bj vol = 1,52). A sobreposição de nicho foi mais marcante para o número de itens consumidos entre as populações (Oij num = 0,82) e menos marcante para volume (Oij vol = 0,05). Nossos dados sugerem diferenças nas dietas entre as duas populações de lagartos, e estas diferenças parecem estar associadas à degradação ambiental. Nossa principal hipótese para explicar as diferenças nas dietas embasa-se na Teoria do Forrageamento Ótimo. Entretanto, o comportamento alimentar, e conseqüentemente a dieta dos lagartos, mostrarem-se limitadas filogeneticamente, com um padrão que pode ter evoluído no ancestral de todos os iguanídeos