Finite element analysis of embedded optical fibre sensors

Micromechanical Finite Element (FE) analysis was used to model stress and strain fields in and around embedded optical fibres EOF'S) in flexural test coupons of carbon fibre composite. The coupons were used in studies of EOF effects on macroscopic laminate properties. The FE method allows complex material inhomogeneities, laminate boundaries and load conditions to be modelled

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Multiplexed fibre-optic system for both local and spatially-averaged strain monitoring

An optical fibre Sensor system to interrogate point sensors (Bragg gratings) and optical path length between point Sensors is discussed. The paper describes interrogation schemes capable of measurement resolutions better than 100 microstrain based on simple optics, telecommunications electronics and sophisticated signal processing

The mechanism of a formaldehyde-sensing transcriptional regulator

Most organisms are exposed to the genotoxic chemical formaldehyde, either from endogenous or environmental sources. Therefore, biology has evolved systems to perceive and detoxify formaldehyde. The frmRA(B) operon that is present in many bacteria represents one such system. The FrmR protein is a transcriptional repressor that is specifically inactivated in the presence of formaldehyde, permitting expression of the formaldehyde detoxification machinery (FrmA and FrmB, when the latter is present). The X-ray structure of the formaldehyde-treated Escherichia coli FrmR (EcFrmR) protein reveals the formation of methylene bridges that link adjacent Pro2 and Cys35 residues in the EcFrmR tetramer. Methylene bridge formation has profound effects on the pattern of surface charge of EcFrmR and combined with biochemical/biophysical data suggests a mechanistic model for formaldehyde-sensing and derepression of frmRA(B) expression in numerous bacterial species