Magmatic-hydrothermal processes play an important role in the transport, enrichment, and mineralization of cesium. In this study, classical molecular dynamics simulations were performed to investigate the properties o...Magmatic-hydrothermal processes play an important role in the transport, enrichment, and mineralization of cesium. In this study, classical molecular dynamics simulations were performed to investigate the properties of Cs-Cl and Cs-F ion pairs in hydrothermal fluids. The association constants(log_(10)K_(A)(m)) under a wide range of temperature(i.e. 298–1273 K) and fluid density(i.e. 0.1–1.0 g/cm^(3)) were derived from the potential of mean force(PMF) curves. The results indicate that CsCl and Cs-F ion pairs have similar stabilities. This is different from other alkali metal cations(e.g., Li^(+), Na^(+), and K^(+)), which prefer binding with F over Cl. The stabilities of Cs-Cl and Cs-F ion pairs increase with increasing temperature(except for the fluid density ≤ 0.1 g/cm^(3)) or decreasing fluid density, which is similar to other alkali halide ion pairs. Comparisons among the stabilities of CsCl/F and other alkali halide ion pairs indicate that the Li–F ion pair has the highest stability in hydrothermal fluids.展开更多
The outer wall of pollen and spores,namely the exine,is composed of sporopollenin,which is highly resistant to chemical reagents and enzymes.In this study,we demonstrated that phenylpropanoid pathway derivatives are e...The outer wall of pollen and spores,namely the exine,is composed of sporopollenin,which is highly resistant to chemical reagents and enzymes.In this study,we demonstrated that phenylpropanoid pathway derivatives are essential components of sporopollenin in seed plants.Spectral analyses showed that the autofluorescence of Lilium and Arabidopsis sporopollenin is similar to that of lignin.Thioacidolysis and NMR analyses of pollen from Lilium and Cryptomeria further revealed that the sporopollenin of seed plants contains phenylpropanoid derivatives,including p-hydroxybenzoate(p-BA),p-coumarate(p-CA),ferulate(FA),and lignin guaiacyl(G)units.The phenylpropanoid pathway is expressed in the tapetum in Arabidopsis,consistent with the fact that the sporopollenin precursor originates from the tapetum.Further germination and comet assays showed that this pathway plays an important role in protection of pollen against UV radiation.In the pteridophyte plant species Ophioglossum vulgatum and Lycopodium clavata,phenylpropanoid derivatives including p-BA and p-CA were also detected,but G units were not.Taken together,our results indicate that phenylpropanoid derivatives are essential for sporopollenin synthesis in vascular plants.In addition,sporopollenin autofluorescence spectra of bryophytes,such as Physcomitrella and Haplocladium,exhibit distinct characteristics compared with those of vascular plants,indicating the diversity of sporopollenin among land plants.展开更多
基金supported by the National Natural Science Foundation of China (Nos 92062213,91855209,42125202 and 41872041)the financial support from the State Key Laboratory for Mineral Deposits Research at Nanjing University。
文摘Magmatic-hydrothermal processes play an important role in the transport, enrichment, and mineralization of cesium. In this study, classical molecular dynamics simulations were performed to investigate the properties of Cs-Cl and Cs-F ion pairs in hydrothermal fluids. The association constants(log_(10)K_(A)(m)) under a wide range of temperature(i.e. 298–1273 K) and fluid density(i.e. 0.1–1.0 g/cm^(3)) were derived from the potential of mean force(PMF) curves. The results indicate that CsCl and Cs-F ion pairs have similar stabilities. This is different from other alkali metal cations(e.g., Li^(+), Na^(+), and K^(+)), which prefer binding with F over Cl. The stabilities of Cs-Cl and Cs-F ion pairs increase with increasing temperature(except for the fluid density ≤ 0.1 g/cm^(3)) or decreasing fluid density, which is similar to other alkali halide ion pairs. Comparisons among the stabilities of CsCl/F and other alkali halide ion pairs indicate that the Li–F ion pair has the highest stability in hydrothermal fluids.
基金grants from the National Key Research and Development Program of China(2016YFD0100902)the National Natural Science Foundation of China(31900165,31870296,31700277)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB27020104)the Program from Shanghai Municipal Education Com mission[2019-01-07-00-02-E00006]the China Postdoctoral Science Foundation(2017M61159)Jiangsu Collaborative Innovation Center for Modern Crop Production(to H.D.Z.).
文摘The outer wall of pollen and spores,namely the exine,is composed of sporopollenin,which is highly resistant to chemical reagents and enzymes.In this study,we demonstrated that phenylpropanoid pathway derivatives are essential components of sporopollenin in seed plants.Spectral analyses showed that the autofluorescence of Lilium and Arabidopsis sporopollenin is similar to that of lignin.Thioacidolysis and NMR analyses of pollen from Lilium and Cryptomeria further revealed that the sporopollenin of seed plants contains phenylpropanoid derivatives,including p-hydroxybenzoate(p-BA),p-coumarate(p-CA),ferulate(FA),and lignin guaiacyl(G)units.The phenylpropanoid pathway is expressed in the tapetum in Arabidopsis,consistent with the fact that the sporopollenin precursor originates from the tapetum.Further germination and comet assays showed that this pathway plays an important role in protection of pollen against UV radiation.In the pteridophyte plant species Ophioglossum vulgatum and Lycopodium clavata,phenylpropanoid derivatives including p-BA and p-CA were also detected,but G units were not.Taken together,our results indicate that phenylpropanoid derivatives are essential for sporopollenin synthesis in vascular plants.In addition,sporopollenin autofluorescence spectra of bryophytes,such as Physcomitrella and Haplocladium,exhibit distinct characteristics compared with those of vascular plants,indicating the diversity of sporopollenin among land plants.
