Volatile organic compounds (VOCs) were collected from damaged and intact mulberry leaves (Morus alba L., Moraceae) and from Hyphantria cunea larvae by headspace absorption with Super Q columns. We identified their constituents using gas chromatography-mass spectrometry, and evaluated the responses of male H. cunea antennae to the compounds using gas chromatography-flame ionization detection coupled with electroantennographic detection. Eleven VOC constituents were found to stimulate antennae of male H. cunea moths: β-ocimene, hexanal, cis-3-hexenal, limonene, trans-2-hexenal, cyclohexanone, cis-2-penten-1-ol, 6-methyl-5-hepten-2-one, 4-hydroxy-4-methyl-2-pentanone, trans-3-hexen-1-ol, and 2,4-dimethyl-3-pentanol. Nine of these chemicals were released by intact, mechanically-damaged, and herbivore-damaged leaves, while cis-2-penten-1-ol was released only by intact and mechanically-damaged leaves and β-ocimene was released only by herbivore-damaged leaves. Results from wind tunnel experiments conducted with volatile components indicated that male moths were significantly more attracted to herbivory-induced volatiles than the solvent control. Furthermore, male moths' attraction to a sex pheromone lure was increased by herbivory-induced compounds and β-ocimene, but reduced by cis-2-penten-1-ol. A proof long-range field trapping experiment showed that the efficiency of sex pheromone lures in trapping male moths was increased by β-ocimene and reduced by cis-2-penten-1-ol.
For the problem of acoustic emission source location, it has always been one of the important issues to look for simple and convenient layout of sensors. This paper presents a new time difference method for locating acoustic emission source in a plate, which the sensors for locating are arranged in a straight line, and does not need the pre-determining of the acoustic wave propagation velocity. The method makes the acoustic emission source locating task simplified.
There are the four types of defects during remote laser welding of zinc coated sheet metal. The root cause of all these defects is the explosion or ejection of molten weld metal caused by the escape of trapped high pressurized zinc vapor. De-gassing gapping is a method used to solve the defects. We have researched the silicon powder de-gassing gapping method for remote laser welding with coupons of zinc coated sheet metal. The result shows that silicon powder de-gassing gapping method works well.
There are the four types of defects during remote laser welding of zinc coated sheet metal. The root cause of all these defects is the explosion or ejection of molten weld metal caused by the escape of trapped high pressurized zinc vapor. Zinc removal is one of the methods used to solve the defects. We have researched the full penetration zinc removal method for remote laser welding with coupons of zinc coated sheet metal. The result shows that the full penetration zinc removal method works at the cost of high heat input and low welding speed
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