The paper attempts to represent a case of repeated failures on a high cut slope due to multi-excavation. The characteristics of each failure induced by excavation are analyzed through geological investigation, and the...The paper attempts to represent a case of repeated failures on a high cut slope due to multi-excavation. The characteristics of each failure induced by excavation are analyzed through geological investigation, and then a geological model at different failure stages is proposed. The geological analysis shows that the excavation-induced repeated failures are related to the exposure of the weak bedding plane and the toe unloading of the cut slope, Numerical modeling is conducted based on a sequential method, taking into account the main failure stages of cut slope. The simulation results fairly coincide with the practical phenomena observed in field. It is shown that the decrease in normal stress of displaced mass on cut slope will induce the increase in shear stress in bedding planes and that at the toe of the cut slope. The released stress leads to repeated gravitational instabilities of cut slope due to the decrease in normal stress and the increase in shear stress along the bedding planes of mudstone.展开更多
Ferric acetylacetonate/covalent organic framework(Fe(acac)_(3)/COF)composite was synthesized by interfacial polymerization method at room temperature.The crystal structure,morphology and porosity property of the compo...Ferric acetylacetonate/covalent organic framework(Fe(acac)_(3)/COF)composite was synthesized by interfacial polymerization method at room temperature.The crystal structure,morphology and porosity property of the composite were characterized by X-ray diffraction,scanning electron microscope,transmission electron microscope and nitrogen adsorption.The interaction between Fe(acac)_(3) and COF was investigated by Fourier transform infrared spectra and X-ray photoelectron spectroscopy.The Fe(acac)_(3)/COF composite was used as a photocatalyst for the oxidation of benzyl alcohol under mild conditions.It exhibits high activity and selectivity for the reaction,of which the mechanism was investigated by determining its photoelectric properties.The Fe(acac)_(3)/COF catalyst developed in this work has application potential in other photocatalytic reactions.展开更多
UiO-66-NH_(2),an important metal-organic framework,is usually synthesized by solvothermal method and the particle size is generally larger than 200 nm,which limits its catalytic applications in chemical reactions.It i...UiO-66-NH_(2),an important metal-organic framework,is usually synthesized by solvothermal method and the particle size is generally larger than 200 nm,which limits its catalytic applications in chemical reactions.It is very meaningful to produce UiO-66-NH_(2) nanoparticles with ultrasmall size,but remains challenging.Herein,we synthesized UiO-66-NH_(2) nanoparticles in size of 8-15 nm that are immobilized on g-C_(3)N_(4)nanosheets.Compared with the UiO-66-NH_(2) synthesized by the traditional solvothermal method(>200 nm),the ultra-small UiO-66-NH_(2) nanoparticles immobilized on g-C_(3)N_(4)have more unsaturated coordination positions and increased Lewis acidity.Owing to these combined advantages,the ultra-small UiO-66-NH_(2)nanoparticles exhibit greatly improved catalytic activity for Meerwein-Ponndorf-Verley reaction than larger UiO-66-NH_(2)particles.展开更多
The proliferation and development of chloroplasts are important for maintaining the normal chloroplast population in plant tissues.Most studies have focused on chloroplast maintenance in leaves.In this study,we identi...The proliferation and development of chloroplasts are important for maintaining the normal chloroplast population in plant tissues.Most studies have focused on chloroplast maintenance in leaves.In this study,we identified a spontaneous mutation in a tomato mutant named suffulta(su),in which the stems appeared albinic while the leaves remained normal.Map-based cloning showed that Su encodes a DnaJ heat shock protein that is a homolog of the Arabidopsis gene AtARC6,which is involved in chloroplast division.Knockdown and knockout of SlARC6 in wild-type tomato inhibit chloroplast division,indicating the conserved function of SlARC6.In su mutants,most mesophyll cells contain only one or two giant chloroplasts,while no chloroplasts are visible in 60%of stem cells,resulting in the albinic phenotype.Compared with mature tissues,the meristem of su mutants suggested that chloroplasts could partially divide in meristematic cells,suggesting the existence of an alternative mechanism in those dividing cells.Interestingly,the adaxial petiole cells of su mutants contain more chloroplasts than the abaxial cells.In addition,prolonged lighting can partially rescue the albinic phenotypes in su mutants,implying that light may promote SlACR6-independent chloroplast development.Our results verify the role of SlACR6 in chloroplast division in tomato and uncover the tissue-specific regulation of chloroplast development.展开更多
It is of great importance to develop facile strategies to synthesize catalysts with desirable compositions and structures for high-performance photocatalytic hydrogen generation. In this work, we put forward an ionic ...It is of great importance to develop facile strategies to synthesize catalysts with desirable compositions and structures for high-performance photocatalytic hydrogen generation. In this work, we put forward an ionic liquid assisted one-pot route for the synthesis of heteroatom-doped Pt/TiO2 composite material. This route is simple, environmentally benign and adjustable owing to the designable properties of ionic liquids. The as-synthesized Pt/TiO2 nanocrystals exhibit high activity and stability for the photocatalytic hydrogen generation under simulated solar irradiation. This method can be easily applied to the synthesis of various kinds of metal/TiO2 composites doped with desirable heteroatoms (e.g., F, Cl, Br, etc).展开更多
To construct the heterojunctions of TiO2 with other compounds is of great importance for overcoming its inherent shortages and improving the visible-light photocatalytic performance.Here we propose the construction of...To construct the heterojunctions of TiO2 with other compounds is of great importance for overcoming its inherent shortages and improving the visible-light photocatalytic performance.Here we propose the construction of TiO2/covalent organic framework(COF)heterojunction with tight connection by a supercritical CO2(SC CO2)method,which helps bridging the transformation paths for photo-induced charge between T i02 and COF.The produced T i02/COF heterojunction performs a H2 evolution of 3,962 nmol·g^-1·h^-1 under visible-light irradiation,which is-25 times higher than that of pure TiO2 and 4.5 folds higher than that of TiO2/COF synthesized by the conventional solvothermal method.This study opens up new possibilities for constructing heterojunctions for solar energy utilization.展开更多
基金Supported by the National Natural Science Foundation of China(41072213 and 40801212)the Opening Fund of Key Laboratory of Mechanics on Disaster and Environment in Western China, Lanzhou University(201207)
文摘The paper attempts to represent a case of repeated failures on a high cut slope due to multi-excavation. The characteristics of each failure induced by excavation are analyzed through geological investigation, and then a geological model at different failure stages is proposed. The geological analysis shows that the excavation-induced repeated failures are related to the exposure of the weak bedding plane and the toe unloading of the cut slope, Numerical modeling is conducted based on a sequential method, taking into account the main failure stages of cut slope. The simulation results fairly coincide with the practical phenomena observed in field. It is shown that the decrease in normal stress of displaced mass on cut slope will induce the increase in shear stress in bedding planes and that at the toe of the cut slope. The released stress leads to repeated gravitational instabilities of cut slope due to the decrease in normal stress and the increase in shear stress along the bedding planes of mudstone.
基金financial supports from National Natural Science Foundation of China(21525316,21673254)Ministry of Science and Technology of China(2017YFA0403003)+1 种基金Chinese Academy of Sciences(QYZDYSSW-SLH013)Beijing Municipal Science&Technology Commission(Z191100007219009).
文摘Ferric acetylacetonate/covalent organic framework(Fe(acac)_(3)/COF)composite was synthesized by interfacial polymerization method at room temperature.The crystal structure,morphology and porosity property of the composite were characterized by X-ray diffraction,scanning electron microscope,transmission electron microscope and nitrogen adsorption.The interaction between Fe(acac)_(3) and COF was investigated by Fourier transform infrared spectra and X-ray photoelectron spectroscopy.The Fe(acac)_(3)/COF composite was used as a photocatalyst for the oxidation of benzyl alcohol under mild conditions.It exhibits high activity and selectivity for the reaction,of which the mechanism was investigated by determining its photoelectric properties.The Fe(acac)_(3)/COF catalyst developed in this work has application potential in other photocatalytic reactions.
基金financial supports from National Natural Science Foundation of China(21525316,21673254)Ministry of Science and Technology of China(2017YFA0403003)+1 种基金Chinese Academy of Sciences(QYZDYSSW-SLH013)Beijing Municipal Science&Technology Commission(Z191100007219009)。
文摘UiO-66-NH_(2),an important metal-organic framework,is usually synthesized by solvothermal method and the particle size is generally larger than 200 nm,which limits its catalytic applications in chemical reactions.It is very meaningful to produce UiO-66-NH_(2) nanoparticles with ultrasmall size,but remains challenging.Herein,we synthesized UiO-66-NH_(2) nanoparticles in size of 8-15 nm that are immobilized on g-C_(3)N_(4)nanosheets.Compared with the UiO-66-NH_(2) synthesized by the traditional solvothermal method(>200 nm),the ultra-small UiO-66-NH_(2) nanoparticles immobilized on g-C_(3)N_(4)have more unsaturated coordination positions and increased Lewis acidity.Owing to these combined advantages,the ultra-small UiO-66-NH_(2)nanoparticles exhibit greatly improved catalytic activity for Meerwein-Ponndorf-Verley reaction than larger UiO-66-NH_(2)particles.
基金supported by funding from the National Key Research and Development Program of China(2018YFD1000800)tp S.W.a grant from the National Natural Science Foundation of China(32000157)to J.C.a grant from the Natural Science Foundation of Fujian Province(2019J01379)to J.C.
文摘The proliferation and development of chloroplasts are important for maintaining the normal chloroplast population in plant tissues.Most studies have focused on chloroplast maintenance in leaves.In this study,we identified a spontaneous mutation in a tomato mutant named suffulta(su),in which the stems appeared albinic while the leaves remained normal.Map-based cloning showed that Su encodes a DnaJ heat shock protein that is a homolog of the Arabidopsis gene AtARC6,which is involved in chloroplast division.Knockdown and knockout of SlARC6 in wild-type tomato inhibit chloroplast division,indicating the conserved function of SlARC6.In su mutants,most mesophyll cells contain only one or two giant chloroplasts,while no chloroplasts are visible in 60%of stem cells,resulting in the albinic phenotype.Compared with mature tissues,the meristem of su mutants suggested that chloroplasts could partially divide in meristematic cells,suggesting the existence of an alternative mechanism in those dividing cells.Interestingly,the adaxial petiole cells of su mutants contain more chloroplasts than the abaxial cells.In addition,prolonged lighting can partially rescue the albinic phenotypes in su mutants,implying that light may promote SlACR6-independent chloroplast development.Our results verify the role of SlACR6 in chloroplast division in tomato and uncover the tissue-specific regulation of chloroplast development.
基金the National Natural Science Foundation of China (Nos.21525316 and 21673254)Ministry of Science and Technology of China (No.2017YFA0403003)+1 种基金Chinese Academy of Sciences (No.QYZDY-SSW-SLH013)Beijing Municipal Science & Technology Commission (No.Z181100004218004).
文摘It is of great importance to develop facile strategies to synthesize catalysts with desirable compositions and structures for high-performance photocatalytic hydrogen generation. In this work, we put forward an ionic liquid assisted one-pot route for the synthesis of heteroatom-doped Pt/TiO2 composite material. This route is simple, environmentally benign and adjustable owing to the designable properties of ionic liquids. The as-synthesized Pt/TiO2 nanocrystals exhibit high activity and stability for the photocatalytic hydrogen generation under simulated solar irradiation. This method can be easily applied to the synthesis of various kinds of metal/TiO2 composites doped with desirable heteroatoms (e.g., F, Cl, Br, etc).
基金The authors thank the financial supports from M inistry of Science and Technology of China(No.2017YFA0403003)the National Natural Science Foundation of China(Nos.21525316 and 21673254)+1 种基金Chinese Academy of Sciences(No.QYZDYSSW-SLH013)Beijing Municipal Science&Technology Commission(No.Z191100007219009).
文摘To construct the heterojunctions of TiO2 with other compounds is of great importance for overcoming its inherent shortages and improving the visible-light photocatalytic performance.Here we propose the construction of TiO2/covalent organic framework(COF)heterojunction with tight connection by a supercritical CO2(SC CO2)method,which helps bridging the transformation paths for photo-induced charge between T i02 and COF.The produced T i02/COF heterojunction performs a H2 evolution of 3,962 nmol·g^-1·h^-1 under visible-light irradiation,which is-25 times higher than that of pure TiO2 and 4.5 folds higher than that of TiO2/COF synthesized by the conventional solvothermal method.This study opens up new possibilities for constructing heterojunctions for solar energy utilization.
