Characterization Of Boron Doped Nanocrystalline Diamonds

Nanostructured diamond doped with boron was prepared using a hot-filament assisted chemical vapour deposition system fed with an ethyl alcohol, hydrogen and argon mixture. The reduction of the diamond grains to the nanoscale was produced by secondary nucleation and defects induced by argon and boron atoms via surface reactions during chemical vapour deposition. Raman measurements show that the samples are nanodiamonds embedded in a matrix of graphite and disordered carbon grains, while morphological investigations using field electron scanning microscopy show that the size of the grains ranges from 20 to 100 nm. The lowest threshold fields achieved were in the 1.6 to 2.4 V/μm range. © 2008 IOP Publishing Ltd.100PART 5Himpsel, F.J., Knapp, J.A., VanVechten, J.A., Eastman, P.E., (1979) Phys. Rev., 20 B, p. 624Bandis, B., Pate, B.B., (1996) Appl. Phys Lett., 69, p. 366Mammana, V.P., Santos, T.E.A., Mammana, A., Baranauskas, V., Ceragioli, H.J., Peterlevitz, A.C., (2002) Appl. Phys. Lett., 81, p. 3470Baranauskas, V., Fontana, M., Ceragioli, H.J., Peterlevitz, A.C., (2004) Nanotech., 15 (10), pp. S678Shroder, R.E., Nemanich, R.J., Glass, J.T., (1990) Phys. Rev., 41 B, p. 3738Ferrari, A.C., Robertson, J., (2001) Phys. Rev., 63 B. , 121405(R)Jiang, X., Frederick, C.K.Au., Lee, S.T., (2002) J. Appl. Phys., 92 (5), p. 2880Lee, Y.C., Lin, S.J., Lin, I.N., Cheng, H.F., (2005) J. Appl. Phys., 97, p. 05431

Evaluation of MTHFR C677T gene polymorphism and homocysteine level in coronary atherosclerotic disease

OBJECTIVE: The aim of this study is to determine the prevalence of C677T methylenetetrahydrofolate reductase (MTHFR) polymorphism and correlate it with plasma homocysteine levels in coronary artery disease (CAD). METHODS: Ninety-three patients with documented CAD from Hospital Universitário Oswaldo Cruz (Recife, PE, Brazil) and 108 healthy controls were evaluated. Homocysteine and folate levels were determined by HPLC and chemoluminescence, respectively, and lipid profile was considered. Genotyping was done by RFLP/PCR. RESULTS: The groups were homogeneous for the C677T polymorphisms. The homocysteine level in cases (11.7 µmol/L) was statistically different from that observed in controls (8.84 µmol/L, p< 0.05). It was also observed that 72% of the patients had homocysteine values above12 µmol/L while the control group presented only 32% in this range. There was no relationship between homozigosity for the C677T polymorphism and the homocysteine level (p= 0.634). We noticed statistical differences between folate levels from patients and controls (6.22 and 7.69 ng/dL, p< 0.05, respectively). However, there was no correlation between homocysteine and folate concentrations in the entire group (r= -0.202). Comparing cases and controls, the odds ratio (OR) when homocysteine is high and folate is low was OR= 11.9; CI 95%= 4.16-34.42, p< 0.01. CONCLUSION: A lack of correlation between C677T mutation and homocysteine level suggests that environmental factors and others genetic factors seem to exert more influence on homocysteine level in this population.OBJETIVO: O objetivo deste trabalho é determinar a prevalência do polimorfismo C677T do gene metilenotetraidrofolato redutase (MTHFR) e associá-la com a concentração plasmática de homocisteína plasmática na doença arterial coronariana (DAC). MÉTODOS: Foram avaliados 93 pacientes com DAC documentada, atendidos no Hospital Universitário Oswaldo Cruz (Recife, PE, Brasil), e 108 controles sem a doença. Foram determinados os perfis lipídicos de pacientes e controles. As concentrações plasmáticas de homocisteína e folato foram determinadas por HPLC e quimioluminescência, respectivamente. A genotipagem foi realizada por RFLP/PCR. RESULTADOS: Os grupos de pacientes e controles foram homogêneos quanto aos perfis genéticos do polimorfismo investigado. Nos pacientes, as concentrações plasmáticas médias de homocisteina (11,7 ± 4,4 µmol/L) e de folato (6,22 ± 3,0 ng/dL) foram estatisticamente diferentes daquelas observadas nos controles (8,84 ± 3,2 µmol/L e 7,69 ± 3,1 ng/dL, respectivamente), ao nível de significância de 0,05. Entretanto, não houve correlação entre concentração plasmática de homocisteína e folato nos pacientes (r= -0,202). Não foi observada associação entre a homozigosidade 677TT para MTHFR e a concentração plasmática de homocisteína sérica (p= 0,634). A comparação dos casos e controles que apresentaram simultaneamente alta concentração plasmática de homocisteína e baixa concentração de folato, resultou numa razão de chance superior à de cada variável analisada independentemente (RC= 11,9; IC 95%= 4,16-34,42, p< 0,01). CONCLUSÕES: A mutação C677T não parece ser um fator genético importante capaz de explicar a hiperhomocisteinemia moderada observada nos pacientes com DAC. Outros fatores, ambientais e genéticos, devem ser investigados.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo (UNIFESP) Departamento de Pediatria Laboratório de Erros Inatos de MetabolismoUniversidade de Pernambuco ICB Departamento de Ciências FisiológicasUniversidade de São Paulo Faculdade de Medicina de Ribeirão Preto Hospital das ClínicasUNIFESP, Depto. de Pediatria Laboratório de Erros Inatos de MetabolismoSciEL

An assessment of composite repair system in offshore platform for corroded circumferential welds in super duplex steel pipe

The main aim of this study is to assess the effectiveness of a composite repair system in severely corroded circumferential welds in super duplex stainless steel pipes as a preventive measure against the premature corrosion damage at the welds. Artificial defects were fabricated on the super duplex steel tube in order to reproduce the localized corrosion damage defects found in real welded joints. Three kinds of through thickness defects were considered: 25%, 50% and 96% of the perimeter of the pipe. The performance of the repaired pipe was assessed by hydrostatic tests as per ISO 24817 standard. The results showed that the composite repair system can sustain the designed failure pressure even for the pipe damaged with through-wall defect up to 96% of the perimeter of the pipe. Hence, the composite repair system can be used as a preliminary tool to protect the unexpected or premature failure at the welds and maintain an adequate level of mechanical strength for a given operating pressure. This composite repair system can assure that the pipe will not leak until a planned maintenance of the line. Nevertheless, further work is still desirable to improve the confidence in the long-term performance of bonded composite

Vulnerable marine ecosystems and biological features of Gazul mud volcano (Gulf of Cádiz): A contribution towards a potential "Gulf of Cádiz" EBSA

The Gulf of Cádiz (GoC) represents an area of socioeconomic and scientific importance for oceanographic, geological and biological processes. An interesting feature of the GoC is the presence of a large amount of mud volcanoes (MVs) and diapirs that display different seepage, seabed types, oceanographic settings and biological communities. Detailed exploration of some MVs is still needed for detecting Vulnerable Marine ecosystems (VMEs) that seem to be rare in other areas of the GoC, improving the current knowledge on its biodiversity and ecological attributes. During different expeditions (MEDWAVES-ATLAS, INDEMARES-CHICA 0610 & 0412 and ISUNEPCA 0616) carried out in different years, biological samples and videos were obtained in Gazul MV (Spanish Margin of the GoC). The study of those samples and videos has revealed the presence of several ecologically important VMEs (e.g. 3 species of reef framework-forming corals, coral gardens including solitary scleractinians, gorgonians and antipatharians, as well as deep-sea sponge aggregations and chemosynthesis-related structures) and a large number of species occurring in this MV, including new records for the European margin, threatened species and non-previously described species. The combination of different environmental and anthropogenic factors allowed the present-day persistence of these VMEs in the GoC. Some of Gazul MV biological and ecological attributes fit several criteria of the Convention on Biological Diversity for EBSA description (e.g. 1,3,4,6) that, together with those of other areas of the GoC, may contribute to the future potential nomination of an EBSA in this area of the NE Atlantic

Online peer assessment in higher education: a systematic review of literature in educational practices

Neste artigo procedemos a uma revisão sistemática da literatura sobre Online Peer Assessment (OPA) no Ensino Superior, mediadas por Tecnologias Digitais de Informação e Comunicação (TIC). Identificamos suas características, centrais e opcionais e mapeamos exemplos práticos (procedimentos e TIC) de OPA que poderão ser transversais, adaptáveis e aplicáveis em diversas unidades curriculares e regimes educacionais. Os resultados apontam para a utilização da OPA como uma estratégia que potencia a “avaliação para a aprendizagem”. Os referenciais teóricos subjacentes, os métodos de avaliação e os tipos de TIC utilizadas indicam seu direcionamento para um maior envolvimento e responsabilidade do aluno na sua aprendizagem. Evidenciamos na literatura que se busca desenvolver essas competências, dando ao aluno oportunidades com alguma regularidade para autoavaliar-se e avaliar seus pares por meio de feedback construtivo. Há também evidências de que dar ou produzir feedback é mais benéfico para a aprendizagem do que apenas recebê-lo, como também é cognitivamente mais exigente e envolve os alunos de forma mais ativa e os direciona ao pensamento crítico e a processos metacognitivos. A partir dos resultados alcançados, consideramos que a OPA, enquanto ferramenta cognitiva, contribui para a construção do conhecimento e para a reflexão sobre a aprendizagem. Um desafio que se coloca diz respeito ao desenvolvimento criativo com foco na diversificação e na inovação das práticas de avaliação no sentido de potenciar aprendizagens e resultados acadêmicos, em atenção às necessidades de aprendizagem que se manifestam frente às expectativas da educação atual e futura e às exigências da sociedade.In this research a systematic review of literature about Online Peer Assessment (OPA) in higher education, mediated by Information and Communication Technology (ICT), was carried out. Optional and central characteristics and its practices (procedures and ICT) were identified and mapping. These procedures and practices may be transversal, adaptable and applied in several curriculum units and educational regimes. The results point to the use of OPA as a strategy that enhances “assessment for learning”. The theoretical framework, the methods of assessment and the kinds of ICT used indicate directions for greater involvement and responsibility from the part of the student in his/her learning. Theoretical framework identifies the need to develop students’ skills, providing them with opportunities for self-assessment and peer assessment on a regular basis through constructive feedback. There is also evidence that to give or receive feedback is more beneficial for learning than just receiving it. It is also cognitively more demanding and directs the students to critical thinking and metacognitive processes. From the results obtained, OPA is seen as a cognitive tool, contributing to the building of knowledge and to reflection about learning. Issues for further reflection are also identified such as the creative development of assessment methods with a focus on diversity and innovation in order to enhance students’ learning and academic results, taking into account their learning needs in face of the expectations of current and future education and the demands of society.CIEC - Centro de Investigação em Estudos da Criança, IE, UMinho (UI 317 da FCT), PortugalFundos Nacionais através da FCT (Fundação para a Ciência e a Tecnologia) e cofinanciado pelo Fundo Europeu de Desenvolvimento Regional (FEDER) através do COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) com a referência POCI-01-0145-FEDER-007562info:eu-repo/semantics/publishedVersio