The mutagenicity of diesel exhaust particles (DEP) was studied by using Salmonella typhimurium strains TA98 and TA100o in vitro and mice micronucleus in vivo test. DEP from six kinds of medium and heavy-duty diesel ve...The mutagenicity of diesel exhaust particles (DEP) was studied by using Salmonella typhimurium strains TA98 and TA100o in vitro and mice micronucleus in vivo test. DEP from six kinds of medium and heavy-duty diesel vehicles, which were made in China and imported, were tested. The vehicles were operated under free accelerating condition. The results showed that the DEP contained mutagenic activity. An increase in the number of the Salmonella TA98 was observed in the presence and especially in the absence of S9 mix. Positive results were also obtained from mice micronucleus assay. The frequency of mice bone marrow micronucleated polychromatic erythrocytes (M PCE) was increased and it showed a definite dose-response relationship. Comparing the different types of the vehicles,we found that the mutagenicity of DEP from domestic made vehicles was stronger than that from the imported ones展开更多
Amazing achievements and accomplishments of space science and technologies in the past half-century have profoundly affected all disciplines of natural science and engineering. By the end of 20(th) Century, man or man...Amazing achievements and accomplishments of space science and technologies in the past half-century have profoundly affected all disciplines of natural science and engineering. By the end of 20(th) Century, man or man-made spacecrafts landed, or approached and surveyed all planets of solar system and their moons except Pluto. Biologists believe that life may emerge and evolve wherever liquid water exists. No liquid water is ever found yet on all planets and their moons in Solar System except for our Earth. Our mother planet turned out to be the only life-supporting oasis within 4 light years of the Milky Way. It is suggested in this article that time has come for science and engineering communities to study and prepare interstellar flight of manned or unmanned spacecrafts beyond Solar System. Four issues are to be addressed as prerequisite for such flight, namely, detailed survey of nearby space beyond Solar System, design of nuclear fusion rocket engine, long-sustainable on-board life-supporting system and breakthrough of the light barrier.展开更多
The excavation of Shanghai Zhidanyun relics makes the recurrence of a splendid Yuan Dynasty sluice. It is a good example for the study of Shanghai history in the Wusongjiang River irrigation, the ancient shipping and ...The excavation of Shanghai Zhidanyun relics makes the recurrence of a splendid Yuan Dynasty sluice. It is a good example for the study of Shanghai history in the Wusongjiang River irrigation, the ancient shipping and the town development. Based on the data of microfossil Pediastrum, Zygnema, Concentricystes, diatom, foraminifera and ostracods from the sediment section of the relics, the paleostream change after the construction of the sluice was guessed. The paleostream was influenced by the sea water due to the connection with the sea in the earlier stage. The upstream of the sea water was enhanced in the middle stage that was indicated by the increase of marine diatoms and foraminifera. The decrease of marine diatoms and foraminifera in abundance reflected that the connection of the paleostream with the sea was reduced, and the sea influence was decreased gradually in the later stage.展开更多
文摘The mutagenicity of diesel exhaust particles (DEP) was studied by using Salmonella typhimurium strains TA98 and TA100o in vitro and mice micronucleus in vivo test. DEP from six kinds of medium and heavy-duty diesel vehicles, which were made in China and imported, were tested. The vehicles were operated under free accelerating condition. The results showed that the DEP contained mutagenic activity. An increase in the number of the Salmonella TA98 was observed in the presence and especially in the absence of S9 mix. Positive results were also obtained from mice micronucleus assay. The frequency of mice bone marrow micronucleated polychromatic erythrocytes (M PCE) was increased and it showed a definite dose-response relationship. Comparing the different types of the vehicles,we found that the mutagenicity of DEP from domestic made vehicles was stronger than that from the imported ones
文摘Amazing achievements and accomplishments of space science and technologies in the past half-century have profoundly affected all disciplines of natural science and engineering. By the end of 20(th) Century, man or man-made spacecrafts landed, or approached and surveyed all planets of solar system and their moons except Pluto. Biologists believe that life may emerge and evolve wherever liquid water exists. No liquid water is ever found yet on all planets and their moons in Solar System except for our Earth. Our mother planet turned out to be the only life-supporting oasis within 4 light years of the Milky Way. It is suggested in this article that time has come for science and engineering communities to study and prepare interstellar flight of manned or unmanned spacecrafts beyond Solar System. Four issues are to be addressed as prerequisite for such flight, namely, detailed survey of nearby space beyond Solar System, design of nuclear fusion rocket engine, long-sustainable on-board life-supporting system and breakthrough of the light barrier.
基金supported by the National Natural Science Foundation of China (Grant Nos.40276021 and 40146024)the State Key Laboratory of Estuarine and Coastal Research,East China Normal University,and the Key Laboratory of Submarine Geoseiences of State Oceanic Administration.
文摘The excavation of Shanghai Zhidanyun relics makes the recurrence of a splendid Yuan Dynasty sluice. It is a good example for the study of Shanghai history in the Wusongjiang River irrigation, the ancient shipping and the town development. Based on the data of microfossil Pediastrum, Zygnema, Concentricystes, diatom, foraminifera and ostracods from the sediment section of the relics, the paleostream change after the construction of the sluice was guessed. The paleostream was influenced by the sea water due to the connection with the sea in the earlier stage. The upstream of the sea water was enhanced in the middle stage that was indicated by the increase of marine diatoms and foraminifera. The decrease of marine diatoms and foraminifera in abundance reflected that the connection of the paleostream with the sea was reduced, and the sea influence was decreased gradually in the later stage.
