Observations on behavior and ecology of the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) group at Tian-e-Zhou Oxbow of the Yangtze River

The authors made 39 surveys (a total of 161 days) in the Tian-e-Zhou Oxbow of the Yangtze River, China, for observing 13 Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis) captured from the main stream of the Yangtze River and 7 juveniles born in the oxbow from January 1997 to July 2000. The animals were usually divided into several "core" groups and moved around in shallow, muddy-bottom areas with the largest individual in the lead. Each core group was composed of 2-3 animals (either 2 adults, 1 adult and 1 juvenile, 2 adults and 1 juvenile, or 2 adults and 1 calf). Newly-released animals joined the other animals first, and then reorganized their own groups one or two days later. Average breath interval was 34.4 s (+/- s.d. 4.39) for individuals in the group. The animals mated from May through June and gave birth during the second and last ten days of April of the next year. The gestation period was estimated as 310 - 320 days. Calves over 5 months old began to eat small fish. The distance of calves swimming apart from their suspected mothers increased each month. These findings will help in the management of the reserve to protect this unique freshwater porpoise.

湿地植物光合作用向水体供氧能力的试验研究

The results of the examination showed that some wetland plants' leaves and stems above the surface of water have little ability to supply water body with oxygen through roots of themselves while they are photosynthesizing. These plants are calamus(Acorus calamus), cattail(Typha angustifolia), wild rice stem(Zizania caduciflora), Cyoerus alternifokius, and water hyacinth(Eichhornia crassipes). It means that there is no relationship between these plants' photosynthesis and the breath of root cells. But duckweed(Lemna minor) has a small to raise DO 0.44mg·L -1 in average, while it is photosynthesizing during the examination. Reed(Phragmitas communis) may have a little the to provide oxygen for water body through root of itself while it is photosynthesizing. It raised DO 0.30mg·L -1 in average during the examination.

The influencing factors on the macroporous formation in polymer films by water droplet templating

Regular micrometer-size porous polystyrene film is prepared by water droplet templating, i.e. breath figures are stabilized by the polymer in solution and thermocapillary flow arranges them into ordered packing. The influences of polystyrene molecular weight, solvent properties, and the relative humidity of atmosphere on the pattern formation and hole sizes are investigated. Two different kinds of hole packing fashion are also observed and their formation mechanisms are discussed.

Formation of regular hole pattern in polymer films

Ordered macroporous materials recently have attracted much attention. A method that utilizes the condensation of monodisperse water droplets on a polymer solution is proposed for the preparation of honeycomb microporous films. Our results show that it is a general method that can be used for patterning a wide range of polymers. The presence of water vapor and polymer is necessary for the formation of regular holes in films. The formation of hexagonal packing instead of other kinds of packing takes place because the hexagonal packing has the lowest free energy. The formation mechanisms of regular hole pattern and imperfections in the hexagonal packing are proposed.