Formation of Atomic Carbon Chains from Graphene Nanoribbons

The formation of one-dimensional carbon chains from graphene nanoribbons is investigated using it ab initio molecular dynamics. We show under what conditions it is possible to obtain a linear atomic chain via pulling of the graphene nanoribbons. The presence of dimers composed of two-coordinated carbon atoms at the edge of the ribbons is necessary for the formation of the linear chains, otherwise there is simply the full rupture of the structure. The presence of Stone-Wales defects close to these dimers may lead to the formation of longer chains. The local atomic configuration of the suspended atoms indicates the formation of single and triple bonds, which is a characteristic of polyynes.Comment: 4 pages, 5 figure

A Survey on Event-B Decomposition

Model decomposition is a powerful tool to scale the design of large and complex systems. It enables developers to separate components development from the concerns of their integration and orchestration. Event-B is a refinementbased formal method, equipped with three decomposition styles that come with solid semantic foundations and strong tool support. This paper intends to give some useful insights and modelling guidelines for using these decomposition styles, illustrated by an actual development of a master data updating system

Asteroid Impacts on the Ocean and Its Short-term Consequences: a Portuguese Case Study

Any location on Earth might be considered a subject to an asteroid impact because, as previous studies show, they are a proven global threat. the consequences of a collision could be catastrophic, even though such events are rare to occur in a person’s lifetime. Tsunami waves can constitute the greatest threat as the Earth’s surface is mostly water, making the probability of a water impact greater than a ground impact. This work expands the knowledge about asteroid impacts on the ocean and their short-term regional consequences. Three asteroids were assumed to impact the Earth: (1) the 2015 JJ asteroid with a 130 m diameter, (2) the 2020 FA5 asteroid with a 210 m diameter, and (3) the Apophis asteroid, a 370 m wide asteroid. We evaluated the consequences of all impacts, at a 45 degree angle, for a specific case study, where the chosen impact location was the midpoint between Portugal’s mainland, Azores, and Madeira Islands. The cratering process, overpressure, induced thermal radiation, and tsunami waves were assessed, along with the global effects. The overpressure mainly causes structural damage. The thermal radiation has too short a range to reach the studied localities. The tsunami is undoubtedly the most far-reaching and threatening effect of an asteroid impact in the ocean.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

Short-Term Consequences of Asteroid Impacts into the Ocean: A Portuguese Case Study

Asteroid impacts are a proven global threat, meaning that any location on Earth might be a subject to their consequences. Such collisions are not likely in any person’s lifetime, but their aftermath could be catastrophic. As Earth’s surface is mostly water, a water impact is more probable than a ground impact, and tsunami waves could pose a significant threat. This study expands the knowledge about asteroid impacts in the ocean and their regional environmental consequences. Three asteroids were assumed to impact the Earth: (1) the Apophis asteroid, a 370 m wide asteroid, (2) a 204 m in diameter asteroid representative of the average impactor on the near-Earth objects, and (3) a 5 km in diameter asteroid. We evaluated the consequences of all impacts for a specific case study, where the chosen impact location was the midpoint between Portugal’s mainland, Azores, and Madeira Islands. The cratering process, generated seismic shaking, overpressure, ejected material, induced thermal radiation, and tsunami waves were assessed, along with the global effects. The overpressure mainly causes structural damage. The thermal radiation can be devastating but has a short reach. The tsunami is undoubtedly the most far-reaching and threatening effect of an asteroid impact in the ocean.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

23 years of ozone episodes in Portugal: photochemical and/or stratospheric intrusion

Ponencia presentada en: XXXII Jornadas Científicas de la AME y el XIII Encuentro Hispano Luso de Meteorología celebrado en Alcobendas (Madrid), del 28 al 30 de mayo de 2012.This work was supported by Fundação para a Ciência e Tecnologia (FCT) that funded the DYNOZONE Project (Ref.º PTDC/CTE - ATM/105507/2008

Photodynamic activity of chloro(5,10,15,20-tetraphenylporphyrinato)indium(III)

Photodynamic activity of chloro(5,10,15,20-tetraphenylporphyrinato)indium(III) (InTPP) in vitro was investigated for possible use in photodynamic therapy (PDT). The quantum yield of singlet oxygen generation in DMSO of InTPP (F D = 0.72) was higher than 5,10,15,20-tetraphenylporphyrin (TPP) (F D = 0.52). Binding sites between photosensitizers and bovine serum albumin (BSA) are independent while binding sites with human red blood cells (RBC) are cooperatives, with one and four binding sites per molecule, respectively. Binding constants with BSA are (1.15 ± 0.07) × 10(5) and (2.6 ± 0.1) × 10(4) L mol-1 and with RBC are (2.40 ± 0.05) × 10(7) L mol-1 e (7.2 ± 0.2) × 10(4) L mol-1 for InTPP and Photofrin®, respectively. InTPP was more efficient than Photofrin® in the photooxidation of L-tryptophan(Trp) and BSA when higher concentrations (14 µmol L-1) of photosensitizers were used. InTPP was 1.37-1.5 times more effective in the photooxidation of RBC than Photofrin®. Our results indicate that InTPP should be used in future studies of PDT.A atividade fotodinâmica do cloro(5,10,15,20-tetrafenilporfirinato) de índio(III) (InTPP) in vitro foi investigado para possível uso em terapia fotodinâmica (PDT). O rendimento quântico de oxigênio singlete do InTPP (F D = 0,72) em DMSO foi maior que da 5,10,15,20-tetrafenilporfirina (TPP) (F D = 0,52). Os sítios de ligação entre os fotossensibilizadores e albumina bovina (BSA) são independentes e com células vermelhas de sangue humano (RBC) são cooperativos, com um e quatro sítios de ligação por molécula, respectivamente. As constantes de associação com BSA são (1,15 ± 0,07) × 10(5) e (2,6 ± 0,1) × 10(4) L mol-1 e com RBC são (2,40 ± 0,05) × 10(7) L mol-1 e (7,2 ± 0,2) × 10(4) L mol-1 para InTPP e Photofrin®, respectivamente. O InTPP foi mais eficiente do que Photofrin® em fotooxidar L-triptofano (Trp) e BSA quando maiores concentrações dos fotossensibilizadores foram utilizadas (acima de 14 µmol L-1). O InTPP foi 1,37 a 1,5 vezes mais eficaz em fotooxidar as RBC do que Photofrin®. Nossos resultados indicam que o InTPP pode ser usado para estudos futuros de PDT.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP