The relationship between contaminated sediments and deformity frequencies for benthic diatoms was the subject of this study. There were two basic types of diatom deformities observed in this study of Tolo Harbour dia...The relationship between contaminated sediments and deformity frequencies for benthic diatoms was the subject of this study. There were two basic types of diatom deformities observed in this study of Tolo Harbour diatoms: 1. Diatoms with deformed cell wall morphology and 2. diatoms with deformed ornamentation. Deformed individuals of Fragilaria capucina and Achananthes hauckiana Grun. displayed external cell wall deformities while deformed individuals of Diatoma displayed deformities in valve ornamentation. Abnormal cell morphology was used as an indicator of a degraded ecosystem. There was a significant correlation( P <0.05, r s=0.652) between sediment toxicity as reflected by the microtox test and benthic diatom diversity. Species diversity and species richness levels at the twelve sites were closely correlated with one another and inversely correlated with sediment toxicity as reflected by our microtox results( r s=0.809, P <0.01). The microtox test for acute toxicity was correlated ( P <0.05) with diatom species richness. The deformity frequencies and microtox tests were not significantly correlated. This lack of correlation was expected as in numerous laboratory studies, toxic substances were not necessarily mutagenic. The use of diatom deformity frequencies as a means of assessing the mutagenic/teratogenic impacts of anthropogenic substances on a marine benthic diatom community necessitates the enumeration of a large number of diatoms making this method extremely labor intensive.展开更多
We study the dynamic behavior of a quartz crystal resonator （QCR） in thickness-shear vibrations with the upper surface covered by an array of micro-beams （MBs） under large deflection. Through taking into account t...We study the dynamic behavior of a quartz crystal resonator （QCR） in thickness-shear vibrations with the upper surface covered by an array of micro-beams （MBs） under large deflection. Through taking into account the continuous conditions of shear force and bending moment at the interface of MBs/resonator, dependences of frequency shift of the compound QCR system versus material parameter and geometrical parameter are illustrated in detail for nonlinear and linear vibrations. It is found that the frequency shift produces a little right （left） translation for increasing elastic modulus （length/radius ratio） of MBs. Moreover, the frequency right （left） translation distance caused by nonlinear deformation becomes more serious in the second-order mode than in the first-order one,展开更多
文摘The relationship between contaminated sediments and deformity frequencies for benthic diatoms was the subject of this study. There were two basic types of diatom deformities observed in this study of Tolo Harbour diatoms: 1. Diatoms with deformed cell wall morphology and 2. diatoms with deformed ornamentation. Deformed individuals of Fragilaria capucina and Achananthes hauckiana Grun. displayed external cell wall deformities while deformed individuals of Diatoma displayed deformities in valve ornamentation. Abnormal cell morphology was used as an indicator of a degraded ecosystem. There was a significant correlation( P <0.05, r s=0.652) between sediment toxicity as reflected by the microtox test and benthic diatom diversity. Species diversity and species richness levels at the twelve sites were closely correlated with one another and inversely correlated with sediment toxicity as reflected by our microtox results( r s=0.809, P <0.01). The microtox test for acute toxicity was correlated ( P <0.05) with diatom species richness. The deformity frequencies and microtox tests were not significantly correlated. This lack of correlation was expected as in numerous laboratory studies, toxic substances were not necessarily mutagenic. The use of diatom deformity frequencies as a means of assessing the mutagenic/teratogenic impacts of anthropogenic substances on a marine benthic diatom community necessitates the enumeration of a large number of diatoms making this method extremely labor intensive.
基金supported by the National Natural Science Foundation of China(11272127 and 51435006)the Research Fund for the Doctoral Program of Higher Education of China(20130142110022)
文摘We study the dynamic behavior of a quartz crystal resonator （QCR） in thickness-shear vibrations with the upper surface covered by an array of micro-beams （MBs） under large deflection. Through taking into account the continuous conditions of shear force and bending moment at the interface of MBs/resonator, dependences of frequency shift of the compound QCR system versus material parameter and geometrical parameter are illustrated in detail for nonlinear and linear vibrations. It is found that the frequency shift produces a little right （left） translation for increasing elastic modulus （length/radius ratio） of MBs. Moreover, the frequency right （left） translation distance caused by nonlinear deformation becomes more serious in the second-order mode than in the first-order one,
