797 resultados para hair fibre metrology


Relevância:

20.00% 20.00%

Publicador:

Resumo:

A sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the detection of several synthetic glucocorticoids in kidney, muscle and hair samples of cattle after a single intramuscular injection is described. After a dichloromethane wash of the hair samples, analytes were released from the hair matrix by enzymatic digestion. Muscle samples were also digested enzymatically using proteinase, while kidney samples were deconjugated by Helix pomatia juice. These preliminary steps were followed by a methanol extraction and a solid phase extraction (SPE) clean up step for all matrices. Chromatographic separation was achieved on a Hypersil Hypercarb column and MS/MS data were obtained in the multiple reaction monitoring mode using negative electrospray ionization. The developed protocols were evaluated by assessing residue concentrations in muscle, kidney and hair samples of thirteen calves, treated with a particular intramuscular injection of glucocorticoid. The lowest residue levels were found in muscle samples (approximately 5% of the residue levels in kidney), while high residue levels were obtained in hair samples. Hair is an interesting matrix since the sampling is non-invasive and the drugs may stay incorporated for a longer period of time. (C) 2004 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Special issue on Sensor Systems for Structural Health Monitoring Abstract—This study addresses the direct calibration of optical fiber strain sensors used for structural monitoring and is carried out in situ. The behavior of fiber-Bragg-grating-based sensor systems when attached to metal bars, in a manner representative of their use as reinforcement bars in structures, was examined and their response calibrated. To ensure the validity of the measurements,this was done using an extensometer with a further calibrationagainst the response of electrical resistance strain gauges, often conventionally used, for comparison. The results show a repeatable calibration generating a suitable geometric factor of extension to strain for these sensors, to enable accurate strain data to be obtained when the fiber-optic sensor system is in use in structural monitoring applications.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This study assessed the effect of increasing fibre levels in the concentrate ration on the welfare of sows housed in a large dynamic group. One hundred and twelve Large White x Landrace sows were allocated to one of two treatments over six replicates. Treatments were as follows: (i) High Fibre diet (similar to 15% CF [Crude Fibre]), and (ii) Control diet (similar to 5% CF). Treatments were applied to two separate dynamic groups each containing 33 (+/- 3) sows in a cross-over design, after three replicates the treatments were switched between the groups. Approximately nine sows were replaced in each of these groups at 3-week intervals (each replacement constituting a replicate of the study). Sows on the high fibre diet spent a greater percentage of time lying (High Fibre: 43.8, Control. 28.0, SEM 3.25%), while sows on the control diet spent more time sham chewing (High Fibre: 7.2, Control: 28.8, SEM 1.55%). Sows newly introduced to the group on the high fibre treatment spent proportionally more time in the kennel areas compared to newly introduced sows in the control treatment (High Fibre. 0.893, Control. 0 788, SEM 5 10) In general, aggression occurred at a very low frequency and overall levels did not differ between treatments (High Fibre: 0.005, Control: 0.003, SEM 0.0007 [occurrences per min)). However, sows in the control treatment performed head thrusting (High Fibre: 0.02, Control: 0.00, SEM 0.001 [occurrences per mini), and biting behaviour (High Fibre. 002, Control. 0.01, SEM 0.002 [occurrences per min]) more frequently than sows on the high fibre diet. There was no effect of treatment on physiological parameters such as plasma cortisol (High Fibre: 1.34, Control: 1.44, SEM 0.114 ng ml(-1)) or haptoglobin levels (High Fibre. 0.73, Control. 0.64, SEM 0.080 mg ml(-1)). In summary, provision of a high fibre diet had a positive effect on the welfare of group-housed dry sows Sows on the high fibre treatment spent more time resting in the kennel areas, less time performing stereotypic behaviours and showed a reduction in some aggressive behaviours relative to sows fed the control diet.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Abstract This work addresses the problems of effective in situ measurement of the initiation or the rate of steel corrosion in reinforced concrete structures through the use of optical fiber sensor systems. By undertaking a series of tests over prolonged periods, coupled with acceleration of corrosion, the performance of fiber Bragg grating-based sensor systems attached to high-tensile steel reinforcement bars (ldquorebarsrdquo), and cast into concrete blocks was determined, and the results compared with those from conventional strain gauges where appropriate. The results show the benefits in the use of optical fiber networks under these circumstances and their ability to deliver data when conventional sensors failed.