PubMed · 10325009
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1978. Project Orbis.. https://pubmed.ncbi.nlm.nih.gov/10325009/
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Caused by time shift, a desynchronisation of the body clock from external zeitgebers occurs after transmeridian flight which leads to disturbances of sleep and circadian rhythms. These disturbances are not pathological and diminish within days. To achieve a faster resynchronisation than naturally, the hormone melatonin is often taken by business people and travelers, and--to some extent--by aircrew. The usefulness of the melatonin intake for alleviation of jet-lag is intensively discussed. Most field studies reporting about a favourable influence of melatonin on jet-lag, have been performed using questionnaires; few studies monitoring physiological circadian functions have found a better adjustment under melatonin treatment. However, from laboratory experiments is known that external melatonin is indeed capable to influence the circadian system. With respect to the efficacy of melatonin on better sleep and performance, there is a lack of information from field studies, and laboratory studies do not provide consistent results. Unequivocal estimations of the dosage of melatonin for best efficacy are not yet performed, although a range of different dosages have been tested. Recommendations about dosage, duration of medication and time of intake (which is of major importance for efficacy) do not rely on systematic examinations of the drug. Adverse effects of melatonin on sleepiness and impaired performance directly after intake of the drug are known. From studies is also derived that an inappropriate timing of intake causes sleep disturbances and unfavourable shifts of the circadian system. The administration of melatonin for influencing sleep and circadian rhythms cannot be recommended for aircrew. Flight physicians should refer to adverse and side effects of the hormone melatonin. Before any general recommendations for the use of melatonin can be presented, genuine clinical studies following good clinical practice should be performed.
Corrosion of aluminum alloy structures costs the US Air Force in the order of US$1 x 10(9) annually. Corrosion develops in areas of overlap such as aircraft lap-splice joints and under protective organic coatings. Capillary electrophoresis (CE) has been used to determine the local chemistries at these corrosion sites of solutions that were extracted using a microsampling system. Analysis of the local solution within lap-splice joints from aircraft has been performed in two ways: rehydration of corrosion products and direct microsampling. The solutions collected were analyzed with CE to quantitatively determine the species present during corrosion. The most common ions detected were Cl-, NO2-, NO3-, HCO3-, K+, Al3+, Ca2+, Na+ and Mg2+. Studies of the solution chemistry under local coating defects are required to understand coating failure and develop more durable coatings. A microsampling system and micro pH sensor were developed to extract solution from and measure pH in defects with diameters as small as 170 microns. Actively corroding defects contained high concentrations of Cl-, Al3+, Mg2+, Mn2+ and Cu2+ whereas only trace levels of Mg2+ were found in repassivated defects. The effects of these species on initiation and propagation of corrosion are discussed.
The flight crews of aircraft often report symptoms including dizziness, nausea, disorientation, blurred vision and tingling in legs and arms. Many of these incidents have been traced to contamination of cabin air with lubricating oil, as well as hydraulic fluid, constituents. Considering that these air contaminants are often subjected to temperatures in excess of 500 degrees C, a large number of different exposures can be expected. Although the reported symptoms are most consistent with exposures to volatile organic compounds, carbon monoxide, and the organophosphate constituents in these oils and fluids, the involvement of these agents has not been clearly demonstrated. Possible exposure to toxic elements, such as lead, mercury, thallium and others, have not been ruled out. In order to assess the potential of exposure to toxic elements a multi-elemental analysis was done on two hydraulic fluids and three lubricating oils which have been implicated in a number of air quality incidents. A secondary objective was to establish if the multi-elemental concentrations of the fluids tested are different enough to allow such an analysis to be used as a possible method of identifying the source of exposure that might have been present during aircraft air quality incidents. No significant concentrations of toxic elements were identified in any of the oils or hydraulic fluids. The elemental compositions of the samples were different enough to be used for identification purposes and the measurement of only three elements was able to achieve this. Whether these findings have an application, in aircraft air quality incident investigations, needs to be established with further studies.