The tidal flat along the Changjiang(Yangtze) River estuary has long been reclaimed for the agricultural purposes, with the prevailing hydrological conditions during such pedogenic transformations being of great import...The tidal flat along the Changjiang(Yangtze) River estuary has long been reclaimed for the agricultural purposes, with the prevailing hydrological conditions during such pedogenic transformations being of great importance to their successful development. In this study, samples of surface sediment from Chongming Dongtan, situated at the mouth of the Changjiang River estuary, were collected and analyzed in order to understand how hydrological management can influence the concentrations of heavy metals and salt ions in pore water, and chemical fractionation of heavy metals during the reclamation process. We performed a series of experiments that simulated three dif ferent hydrological regimes: permanent flooding(R1), alternative five-day periods of wetting and drying(R2), continuous field capacity(R3). Our results exhibited good Pearson correlations coefficients between heavy metals and salt ions in the pore water for both R1 and R2. In particular, the concentrations of salt ions in the pore water decreased in all three regimes, but showed the biggest decline in R2. With this R2 experiment, the periodic concentration patterns in the pore water varied for Fe and Mn, but not for Cr, Cu, Pb and Zn. Neither the fractionation of Ni nor the residual fractions of any metals changed significantly in any regime. In R1, the reducible fractions of heavy metals(Cr, Cu, Zn and Pb) in the sediment decreased, while the acid extractable fractions increased. In R2, the acid extractable and the reducible fractions of Cr, Cu, Zn and Pb both decreased, as did the oxidizable fraction of Cu. These data suggest that an alternating hydrological regime can reduce both salinity and the availability of heavy metals in sediments.展开更多
With the development of economy and society, every comer of the world＇ s cultural and spiritual civilization are closely linked together, At the same time, the clothing and contemporary art are in the big tide of mut...With the development of economy and society, every comer of the world＇ s cultural and spiritual civilization are closely linked together, At the same time, the clothing and contemporary art are in the big tide of mutual penetration and mutual influence. Contemporary art has influenced on the costume design. Costume design can play their own advantages in art tide, toward a higher point. The passage from the clothing design and other fields of contemporary art in the process of cross-border integration explores the future development trend of garment design.展开更多
The 21st century is the era of human recreation. What leisure and sport bring to people is bound to be a civilized, healthy, happy, and new life patterns. Throughout the development of sports and leisure history, we c...The 21st century is the era of human recreation. What leisure and sport bring to people is bound to be a civilized, healthy, happy, and new life patterns. Throughout the development of sports and leisure history, we can see that in the era of leisure sports agricultural, civilization reflects a more casual game. Strictly speaking, leisure sport is a product of the birth of modern industrial civilization. But today, it has become a recreational sport entirely necessities of life, recreation is the ultimate ownership of human beings, but also one of the best state of human existence, and therefore we have reason to believe that in the near future, leisure Sports will bring a self-liberation and ultimate human freedom.展开更多
A ring R is Zhou nil-clean if every element in R is the sum of two tripotents and a nilpotent that commute. Homomorphic images of Zhou nil-clean rings are explored. We prove that a ring R is Zhou nil-clean if and only...A ring R is Zhou nil-clean if every element in R is the sum of two tripotents and a nilpotent that commute. Homomorphic images of Zhou nil-clean rings are explored. We prove that a ring R is Zhou nil-clean if and only if 30 ∈ R is nilpotent and R/30R is Zhou nil-clean, if and only if R/BM（R） is 5-potent and BM（R） is nil, if and only if J（R） is nil and R/J（R） is isomorphic to a Boolean ring, a Yaqub ring, a Bell ring or a direct product of such rings. By means of homomorphic images, we completely determine when the generalized matrix ring is Zhou nil-clean. We prove that the generalized matrix ring Mn（R; s） is Zhou nil-clean if and only if R is Zhou nil-clean and s ∈ J（R）.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.41271466,41671461)
文摘The tidal flat along the Changjiang(Yangtze) River estuary has long been reclaimed for the agricultural purposes, with the prevailing hydrological conditions during such pedogenic transformations being of great importance to their successful development. In this study, samples of surface sediment from Chongming Dongtan, situated at the mouth of the Changjiang River estuary, were collected and analyzed in order to understand how hydrological management can influence the concentrations of heavy metals and salt ions in pore water, and chemical fractionation of heavy metals during the reclamation process. We performed a series of experiments that simulated three dif ferent hydrological regimes: permanent flooding(R1), alternative five-day periods of wetting and drying(R2), continuous field capacity(R3). Our results exhibited good Pearson correlations coefficients between heavy metals and salt ions in the pore water for both R1 and R2. In particular, the concentrations of salt ions in the pore water decreased in all three regimes, but showed the biggest decline in R2. With this R2 experiment, the periodic concentration patterns in the pore water varied for Fe and Mn, but not for Cr, Cu, Pb and Zn. Neither the fractionation of Ni nor the residual fractions of any metals changed significantly in any regime. In R1, the reducible fractions of heavy metals(Cr, Cu, Zn and Pb) in the sediment decreased, while the acid extractable fractions increased. In R2, the acid extractable and the reducible fractions of Cr, Cu, Zn and Pb both decreased, as did the oxidizable fraction of Cu. These data suggest that an alternating hydrological regime can reduce both salinity and the availability of heavy metals in sediments.
文摘With the development of economy and society, every comer of the world＇ s cultural and spiritual civilization are closely linked together, At the same time, the clothing and contemporary art are in the big tide of mutual penetration and mutual influence. Contemporary art has influenced on the costume design. Costume design can play their own advantages in art tide, toward a higher point. The passage from the clothing design and other fields of contemporary art in the process of cross-border integration explores the future development trend of garment design.
文摘The 21st century is the era of human recreation. What leisure and sport bring to people is bound to be a civilized, healthy, happy, and new life patterns. Throughout the development of sports and leisure history, we can see that in the era of leisure sports agricultural, civilization reflects a more casual game. Strictly speaking, leisure sport is a product of the birth of modern industrial civilization. But today, it has become a recreational sport entirely necessities of life, recreation is the ultimate ownership of human beings, but also one of the best state of human existence, and therefore we have reason to believe that in the near future, leisure Sports will bring a self-liberation and ultimate human freedom.
基金The authors are grateful to the referee for his/her careful the paper, and for the invaluable comments which improve our presentation reading of author H.Y. Chen was supported by the Natural Science Foundation of Zhejiang （No. LY17A010018）, China. The first Province
文摘A ring R is Zhou nil-clean if every element in R is the sum of two tripotents and a nilpotent that commute. Homomorphic images of Zhou nil-clean rings are explored. We prove that a ring R is Zhou nil-clean if and only if 30 ∈ R is nilpotent and R/30R is Zhou nil-clean, if and only if R/BM（R） is 5-potent and BM（R） is nil, if and only if J（R） is nil and R/J（R） is isomorphic to a Boolean ring, a Yaqub ring, a Bell ring or a direct product of such rings. By means of homomorphic images, we completely determine when the generalized matrix ring is Zhou nil-clean. We prove that the generalized matrix ring Mn（R; s） is Zhou nil-clean if and only if R is Zhou nil-clean and s ∈ J（R）.
