Abstract. A population of Periophthalmus minutus inhabiting a mudflat in the highest intertidal zone 20in Darwin was investigated for surface activity, feeding and reproduction in relation to environmental 21 conditions in dry (August) and wet seasons (February). On days with tidal inundation, the fish were 22 diurnally active on exposed mudflat surface at low tide, but retreated into burrows during daytime 23 inundation and at night. Temperature above 40°C and heavy precipitation suppressed the daytime 24 surface activity of the fish. During neap tides, the mudflat remained uncovered by the tide for nine 25 days in both seasons. The fish confined themselves in burrows without ingested food throughout the 26 nine-day period in August, but they remained active on mudflat surface and kept foraging in February. 27The salinity of burrow water during the nine-day emersion was extremely high (72 ± 6 psu, mean ± 28 SD) in August, but lower (46 ± 9), though still higher than the open seawater value (34), in February. 29The burrows had a shape of "J" in February, but were straight with no upturn in August. Fertilized

Air was stored in 90% of Boleophthalmus pectinirostris burrows in summer breeding months when fish were active on the mudflat surface during low tide but only in 50% of burrows in overwintering months when the fish confined themselves to burrows. The volume of gas recovered from the burrows ranged from 30 to > 400 ml. The partial pressure of oxygen (PO₂) of the gas varied from 5 to 20 kPa and was inversely related to the partial pressure of carbon dioxide (PCO₂) in all but the wintering periods. Sampling in July demonstrated that gas was stored in both male and female burrows with no difference in volume, PO₂ or PCO₂ between them. Adult fish were able to survive total submersion in hypoxic (PO₂ = 1.96 kPa) water for 8 h, but no embryos survived to hatch in the hypoxic aquatic environment. Thus, the deposited air appears to be a crucial source of oxygen for the embryos developing in the egg chamber of the burrow, but may play only a subsidiary role for adult respiration during presumed high-tide confinement.

Summary:The residual stress and stress corrosion cracking of aluminum brass condenser tubes were studied by means of strain meter and stress corrosion cracking test.The following aspects have been observed.(1) Large tensile stress remains on the inner surface of the brass tube in the vicinity of the expanded tube joint.(2) The stress has a relationship with the clearance between tube and tube sheet before the expanding operation.(3) Closely fitted test pieces reduced the stress and showed good results in stress corrosion cracking test using aqueous ammonia.

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