With Polygonatum cirrhifolium root as the donator, the wheat, cucumber and carrot as receiver plant, the potential allelopathic effects of petroleum extracts, acetic ether extracts, n-butanol extracts and aqueous extr...With Polygonatum cirrhifolium root as the donator, the wheat, cucumber and carrot as receiver plant, the potential allelopathic effects of petroleum extracts, acetic ether extracts, n-butanol extracts and aqueous extracts from donator on the seed germination and seedling growth of three receiver plants were studied by culture plate and filter-paper. The results showed that every extracts had different allelopathic effection on different receiver plant or on different position of same receiver plant. The allelopathy intensity were related to the concentration and strengthen along with the concentration raise. The different receiver plant had distinct sensitive to the the allelopathic effect, cucumber was more sensitive than carrot and wheat. Every extracts had inhibition against seed germination and seedling growth, but inhibited root growth at high concentration and stimulated it at low concentration. In a word, every extracts had more impact on the seedling growth, however, had weak inhibition against seed germination. The average allelopathic effection of acetic ether extracts was more stronger, then n-butanol extracts, aqueous extracts and petroleum extracts. The acetic ether extracts had extremely strong inhibition on the growth of seedling and root, and n-butanol extracts on the seed germination also, which implied the Polygonatum cirrhifolium contained the allelochemicals with high polarity. In rhizosphere soil of P. cirrhifolium , the root and seedlings growth of wheat was stimulated, while cucumber and carrot was inhibited.展开更多
The surface of nanocrystals plays a dominant role in many of their physical and chemical properties.However,controllability and tunability of nanocrystal surfaces remain unsolved.Herein,we report that the surface chem...The surface of nanocrystals plays a dominant role in many of their physical and chemical properties.However,controllability and tunability of nanocrystal surfaces remain unsolved.Herein,we report that the surface chemistry of nanocrystals,such as near-infrared Ag_(2)Se quantum dots(QDs),is sizedependent and composition-tunable.The Ag_(2)Se QDs tend to form a stable metal complex on the surface to minimize the surface energy,and therefore the surface chemistry can be varied with particle size.Meanwhile,changes in surface inorganic composition lead to reorganization of the surface ligands,and the surface chemistry also varies with composition.Therefore,the surface chemistry of Ag_(2)Se QDs,responsible for the photoluminescence(PL)quantum yield and photostability,can be tuned by changing their size or composition.Accordingly,we demonstrate that the PL intensity of the Ag_(2)Se QDs can be tuned reversely by adjusting the degree of surface Ag^(+) enrichment via light irradiation or the addition of AgNO_(3).This work provides insight into the control of QD surface for desired PL properties.展开更多
文摘With Polygonatum cirrhifolium root as the donator, the wheat, cucumber and carrot as receiver plant, the potential allelopathic effects of petroleum extracts, acetic ether extracts, n-butanol extracts and aqueous extracts from donator on the seed germination and seedling growth of three receiver plants were studied by culture plate and filter-paper. The results showed that every extracts had different allelopathic effection on different receiver plant or on different position of same receiver plant. The allelopathy intensity were related to the concentration and strengthen along with the concentration raise. The different receiver plant had distinct sensitive to the the allelopathic effect, cucumber was more sensitive than carrot and wheat. Every extracts had inhibition against seed germination and seedling growth, but inhibited root growth at high concentration and stimulated it at low concentration. In a word, every extracts had more impact on the seedling growth, however, had weak inhibition against seed germination. The average allelopathic effection of acetic ether extracts was more stronger, then n-butanol extracts, aqueous extracts and petroleum extracts. The acetic ether extracts had extremely strong inhibition on the growth of seedling and root, and n-butanol extracts on the seed germination also, which implied the Polygonatum cirrhifolium contained the allelochemicals with high polarity. In rhizosphere soil of P. cirrhifolium , the root and seedlings growth of wheat was stimulated, while cucumber and carrot was inhibited.
基金supported by the National Natural Science Foundation of China(91859123)the National Key R&D Program of China(2019YFA0210103)。
文摘The surface of nanocrystals plays a dominant role in many of their physical and chemical properties.However,controllability and tunability of nanocrystal surfaces remain unsolved.Herein,we report that the surface chemistry of nanocrystals,such as near-infrared Ag_(2)Se quantum dots(QDs),is sizedependent and composition-tunable.The Ag_(2)Se QDs tend to form a stable metal complex on the surface to minimize the surface energy,and therefore the surface chemistry can be varied with particle size.Meanwhile,changes in surface inorganic composition lead to reorganization of the surface ligands,and the surface chemistry also varies with composition.Therefore,the surface chemistry of Ag_(2)Se QDs,responsible for the photoluminescence(PL)quantum yield and photostability,can be tuned by changing their size or composition.Accordingly,we demonstrate that the PL intensity of the Ag_(2)Se QDs can be tuned reversely by adjusting the degree of surface Ag^(+) enrichment via light irradiation or the addition of AgNO_(3).This work provides insight into the control of QD surface for desired PL properties.
