A complete homologous series of fluorescent phosphatidylethanolamines (diC n PE), labelled at the head group with a 7-nitrobenz-2-oxa-1,3-diazo-4-yl(NBD) fluorophore and inserted in 1-palmitoyl, 2-oleoyl-snglycero-3-phosphocholine (POPC) bilayers, was studied using atomistic molecular dynamics simulations. The longer-chained derivatives of NBD-diC n PE, with n = 14, 16, and 18, are commercially available, and widely used as fluorescent membrane probes. Properties such as location of atomic groups and acyl chain order parameters of both POPC and NBD-diC n PE, fluorophore orientation and hydrogen bonding, membrane electrostatic potential and lateral diffusion were calculated for all derivatives in the series. Most of these probes induce local disordering of POPC acyl chains, which is on the whole counterbalanced by ordering resulting from binding of sodium ions to lipid carbonyl/glycerol oxygen atoms. An exception is found for NBD-diC 16 PE, which displays optimal matching with POPC acyl chain length and induces a slight local ordering of phospholipid acyl chains. Compared to previously studied fatty amines, acyl chain-labelled phosphatidylcholines, and sterols bearing the same fluorescent tag, the chromophore in NBD-diC n PE locates in a similar region of the membrane (near the glycerol backbone/carbonyl region) but adopts a different orientation (with the NO 2 group facing the interior of the bilayer). This modification leads to an inverted orientation of the P-N axis in the labelled lipid, which affects the interface properties, such as the membrane electrostatic potential and hydrogen bonding to lipid head group atoms. The implications of this study for the interpretation of the photophysical properties of NBD-diC n PE (complex fluorescence emission kinetics, differences with other NBD lipid probes) are discussed.

We present a cost-effective solution for applications of monitoring of accident risks based on an interest-centric opportunistic secure-communication network, namely RadNet. The monitoring system provides regular collection of events and its transmission to a system of control of accident risks and Forensic Audit. To this end, event transmission requires Confidentiality, Integrity, and Availability, a triad that RadNet can satisfy by mitigating the vulnerabilities of using IP addresses and end-to-end communication. Resumo. Apresentamos uma solução custo-efetiva para aplicações de monitoramento de riscos de sinistros baseada em uma rede oportunística de comunicação segura centrada em interesses, denominada RadNet. O sistema de monitoramento provê a coleta regular de eventos e sua transmissão para um sistema de controle de riscos de sinistros e Auditoria Forense. Para este fim, a transmissão de eventos exige Confidencialidade, Integridade e Disponibilidade, tríade que a RadNet consegue satisfazer ao mitigar as vulnerabilidades de utilização de endereços IP e comunicação fim-a-fim.