A diastereo- and enantiocontrolled preparation of the conformationally restricted cis-β-azidocyclopropane esters have been developed. The Rh(2)(S-DOSP)(4) was found to be an efficient catalyst in hexane for the cyclopropanation of azido alkenes with diazo esters, and 19 cis-β-azidocyclopropane esters were prepared in excellent yields. The value of the diastereomer ratio was up to 99:1, and the enantiomeric excess was up to 95%. Furthermore, the relative and absolute configuration was confirmed by X-ray analysis.
Abstract. BACKGROUND: Human factors involved with visual attention mechanism and fatigue are critical causes of modern aviation accidents. OBJECTIVE: To investigate the connection between attention and flight fatigue, a mathematical model of pilot's visual attention allocation was established based on information processing channels. Multi-task condition and current psychophysical state were taken into account as well. METHODS: Sixteen participants were recruited to perform a long-term dual-task in a Boeing 737-800 flight simulator. The primary task was an envelope flight task and the secondary was an unusual attitude (UA) recovery task. Reaction time of the secondary task was recorded as a behavior performance index, while heart rate and respiration rate were measured as physiological indices as well as fixation distribution as attention allocation index.
RESULTS:The experiment results showed a significant affect of experiment time that indicated the occurrence and influence of fatigue. Eye movement tracking also revealed good agreement with the predictable model and hence verified its effectiveness. Moreover, applicability of the model was validated under flight fatigue and multiple tasks condition. CONCLUSION: The current study provided a quantitative connection between pilot's visual attention allocation and flight fatigue, which was verified in the ergonomics experiment.
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