Dinoflagellates nuclei allow for liquid crystalline characterization without core histones. In this study, nuclei were isolated from the athecate Karenia dinoflagellate species with minimum destruction to their native...Dinoflagellates nuclei allow for liquid crystalline characterization without core histones. In this study, nuclei were isolated from the athecate Karenia dinoflagellate species with minimum destruction to their native structure during preparation procedures. The liquid crystalline nuclei were studied by microscopy techniques of Metripol birefringence microscopy, Confocal Laser Scanning Microscopy (CLSM) and synchrotron radiation-based hard X-ray Microscopy with computed tomography, respectively. The 3D reconstruction techniques of hard X-ray tomography and CLSM were also discussed. The important biophysical parameters of the interspaces between chromosomes, nuclear surface areas and chromosome-occupied volumes were calculated from a 3D rendering of a reconstructed nucleus. The results of calculated average chromosomal DNA concentration of dinoflagellate was consistent with the concentration which can spontaneously assemble into the cholesteric liquid crystal phase in vitro.展开更多
Tests were conducted on 3 specimens to study the flexural behavior of fiber reinforced polymer(FRP)-concrete-steel double-skin tubular members(DSTMs).The strip method was used to calculate the section momentcurvature ...Tests were conducted on 3 specimens to study the flexural behavior of fiber reinforced polymer(FRP)-concrete-steel double-skin tubular members(DSTMs).The strip method was used to calculate the section momentcurvature curves of the 3 specimens and 12 models.A theoretical formula is presented for the flexural strength of DSTMs.The test results show that the tension zone of the specimen FRP tubes was in hoop compression while the compression zone was in hoop tension.The load-carrying capacity did not decrease even when the mid-span deflection reached about 1/24 of the span length.The tests,simulation and theoretical analysis resulted in a simplified formula for the flexural strength of DSTMs and a tri-linear moment-curvature model was expressed as a function of the section bending stiffness for DSTMs.展开更多
Calcified coccolithophores, a diverse and widely distributed group of marine microalgae, produce biogenic calcite in the form ofcoccoliths located on the cell surface. Using batch incubations of the coccolithophorid P...Calcified coccolithophores, a diverse and widely distributed group of marine microalgae, produce biogenic calcite in the form ofcoccoliths located on the cell surface. Using batch incubations of the coccolithophorid Pleurochrysis carterae, we investigated the responses of this calcification process to iron concentrations by changing the iron supply in the initial culture media from a normal concentration to 1 ppm （parts per million）, 5 ppm, and 10 ppm. Time-dependent measurements of cell population, production of inorganic carbon （coccoliths）, and organic carbon （organic cellular components） showed that elevated iron supply in the growth medium of P. carterae stimulates carbon sequestration by increasing growth along enhanced photosynthetic activity and calcification. In addition, the acquired time-dependent UV-Vis and FT-IR spectra revealed that iron fertilization- enhanced coccolith calcification is accompanied by a crystalline phase transition from calcite to aragonite or amorphous phase. Our results suggest that iron concentration has a significant influence on the marine carbon cycle of coccolithophores.展开更多
文摘Dinoflagellates nuclei allow for liquid crystalline characterization without core histones. In this study, nuclei were isolated from the athecate Karenia dinoflagellate species with minimum destruction to their native structure during preparation procedures. The liquid crystalline nuclei were studied by microscopy techniques of Metripol birefringence microscopy, Confocal Laser Scanning Microscopy (CLSM) and synchrotron radiation-based hard X-ray Microscopy with computed tomography, respectively. The 3D reconstruction techniques of hard X-ray tomography and CLSM were also discussed. The important biophysical parameters of the interspaces between chromosomes, nuclear surface areas and chromosome-occupied volumes were calculated from a 3D rendering of a reconstructed nucleus. The results of calculated average chromosomal DNA concentration of dinoflagellate was consistent with the concentration which can spontaneously assemble into the cholesteric liquid crystal phase in vitro.
基金supported by the National Science Foundation of China(Grant No.50329802).
文摘Tests were conducted on 3 specimens to study the flexural behavior of fiber reinforced polymer(FRP)-concrete-steel double-skin tubular members(DSTMs).The strip method was used to calculate the section momentcurvature curves of the 3 specimens and 12 models.A theoretical formula is presented for the flexural strength of DSTMs.The test results show that the tension zone of the specimen FRP tubes was in hoop compression while the compression zone was in hoop tension.The load-carrying capacity did not decrease even when the mid-span deflection reached about 1/24 of the span length.The tests,simulation and theoretical analysis resulted in a simplified formula for the flexural strength of DSTMs and a tri-linear moment-curvature model was expressed as a function of the section bending stiffness for DSTMs.
文摘Calcified coccolithophores, a diverse and widely distributed group of marine microalgae, produce biogenic calcite in the form ofcoccoliths located on the cell surface. Using batch incubations of the coccolithophorid Pleurochrysis carterae, we investigated the responses of this calcification process to iron concentrations by changing the iron supply in the initial culture media from a normal concentration to 1 ppm （parts per million）, 5 ppm, and 10 ppm. Time-dependent measurements of cell population, production of inorganic carbon （coccoliths）, and organic carbon （organic cellular components） showed that elevated iron supply in the growth medium of P. carterae stimulates carbon sequestration by increasing growth along enhanced photosynthetic activity and calcification. In addition, the acquired time-dependent UV-Vis and FT-IR spectra revealed that iron fertilization- enhanced coccolith calcification is accompanied by a crystalline phase transition from calcite to aragonite or amorphous phase. Our results suggest that iron concentration has a significant influence on the marine carbon cycle of coccolithophores.
