环境中与日俱增的有机污染物严重危害着生态环境和人体健康.先前研究往往忽视了有机污染物分子团簇(molecular cluster of organic contaminants,MCOCs)的影响,而MCOCs的形成可能改变有机污染物的理化特性,进而影响其环境行为和归趋.分...环境中与日俱增的有机污染物严重危害着生态环境和人体健康.先前研究往往忽视了有机污染物分子团簇(molecular cluster of organic contaminants,MCOCs)的影响,而MCOCs的形成可能改变有机污染物的理化特性,进而影响其环境行为和归趋.分子结构特性及环境条件决定了有机污染物的赋存状态(分子态、离子态、团簇态和沉淀态),也进一步决定了其环境行为和风险.比如,MCOCs相较于其它赋存状态可能更有利于其被快速吸附,但也可能由于其尺寸较大而限制了在孔隙内的活动.文章综述了决定有机污染物(多环芳烃、邻苯二甲酸酯、其它有机污染物)赋存状态的因素以及它们的环境行为和环境效应,并总结了MCOCs形成的普遍性和显著性,着重强调了它们的环境行为、效应及潜在的环境风险,旨在为有机污染物的环境行为和效应研究以及其污染控制策略的形成提供理论支撑.展开更多
Wheat ( Triticum aestivum L.) plants were grown under ambient and doubled_CO 2(plus 350 μL/L) concentration in cylindrical open_top chamber to examine their effects on the ultrastructure, supramolecular architect...Wheat ( Triticum aestivum L.) plants were grown under ambient and doubled_CO 2(plus 350 μL/L) concentration in cylindrical open_top chamber to examine their effects on the ultrastructure, supramolecular architecture, absorption spectrum and low temperature (77 K) fluorescence emission spectrum of the chloroplasts from wheat leaves. The results were briefly summarized as follows: (1) The wheat leaves possessed normally developed chloroplasts with intact grana and stroma thylakoid membranes; The grana intertwined with stroma thylakoid membranes and increased slightly in stacking degree and the width of granum, in spite of more accumulated starch grains within the chloroplasts than those in control; (2) The particle density in the stacked region of the endoplasmic fracture face (EFs) and protoplasmic fracture face (PFs) and in the unstacked region the endoplasmic fracture face (EFu) and the protoplasmic fracture face (PFu) was significantly higher than that of control. Furthermore, in some cases many more particles on EFs faces of thylakoid membranes appeared as a paracrystalline particle array; (3) The variations in the structure of chloroplasts were consistent with the absorption spectra and the low temperature (77 K) fluorescence emission spectra of the chloroplasts developed under the doubled_CO 2 concentration. Results indicate that the capability of light energy absorption of chloroplasts and regulative capability of excitation energy distribution between PSⅡ and PSⅠ were raised by doubled_CO 2 concentration. This is very favorable for final productivity of wheat.展开更多
Viral nonstructural proteins in both enveloped and non-enveloped viruses play important roles in viral replication. Protein NS38 of Grass carp reovirus (GCRV), has been deduced to be a non-structural protein, and, con...Viral nonstructural proteins in both enveloped and non-enveloped viruses play important roles in viral replication. Protein NS38 of Grass carp reovirus (GCRV), has been deduced to be a non-structural protein, and, consistent with other reoviruses, is considered to cooperate with the NS80 protein in viral particle assembly. To investigate the molecular basis of the role of NS38, a complete protein was expressed in E.coli for the first time. It was found that there is a better expression of NS38 induced with IPTG at 28 ℃ rather than 37 ℃. In addition, the antiserum of NS38 prepared with purified fusion protein and injected into rabbit could be used for detecting NS38 protein expression in GCRV infected cell lysate, while there is not any reaction crossed with purified virus particle, confirming NS38 is not a component of the viral structural protein. The result reported in this study will provide evidence for further viral protein-protein and protein-RNA interaction in dsRNA viruses replication.展开更多
Highly efficient synthesis methods have been developed and characteristics of nanometallocarbosilanes molecular structure were studied by the research team of GNIIChTEOS （State Research Institute for Chemistry and Te...Highly efficient synthesis methods have been developed and characteristics of nanometallocarbosilanes molecular structure were studied by the research team of GNIIChTEOS （State Research Institute for Chemistry and Technology of Organoelement Compounds）. Nanometallocarbosilanes were synthesized by thermal co-condensation of oligocarbosilanes and alkyl amides of refractory metals. Initial, intermediate and final products of side reactions were characterized by 1H, 13C, 29Si NMR （nuclear magnetic resonance）, IR （infra-red） spectroscopy, GPC （gel-penetrating chromatography）, TGA （thermal gravimetric analysis）, TEM （transmission electron microscopy）, SEM （scanning electron microscopy）, RES （X-ray phase analysis） and elemental analysis. The proposed synthesis method of nanometallocarbosilanes was lbund to produce fusable soluble organosilicon oligomers with homogeneous distribution of nanoscale （10-20 nm） metal particles in the oligomer matrix. A computational model of the group and elemental composition of nanometallocarbosilanes was developed; it was shown that they are molecular globules of near-spherical shape and rigid polycyclic structure. Thermochemical treatment of nanometallocarbosilanes leads to SiC-nanoceramics （a high yield of up to 75-80 mass%） modified by metal nanoparticles （20-30 nm） contributing to its stabilization. The application of preceramic oxygen-free nanometallocarbosilanes will make it possible to advance in solving the problem of ceramic composite materials with long-term resistance at temperatures above 1,500 ℃ in oxidizing environments.展开更多
The effect of terminal groups on the electron transport through metal-molecule-metal system has been investigated using nonequilibrium Green's function (NEGF) formalism combined with extended Huckel theory (EHT). ...The effect of terminal groups on the electron transport through metal-molecule-metal system has been investigated using nonequilibrium Green's function (NEGF) formalism combined with extended Huckel theory (EHT). Au-molecule-Au junctions are constructed with borazine and BCN unit structure as core molecule and sulphur (S), oxygen (O), selenium (Se) and cyano-group (CN) as terminal groups. The electron transport characteristics of the borazine and BCN molecular systems are analyzed through the transmission spectra and the current-voltage curve. The results demonstrate that the terminal groups modifying the transport behaviors of these systems in a controlled way. Our result shows that, selenium is the best linker to couple borazine to Au electrode and oxygen is the best one to couple BCN to Au electrode. Furthermore, the results of borazine systems are compared with that of BCN molecular systems and are discussed. Simulation results show that the conductance through BCN molecular systems is four times larger than the borazine molecular systems. Negative differential resistance behavior is observed with borazine-CN system and the saturation feature appears in BCN systems.展开更多
The structural and dynamic properties of nanoscale ethanol film on a mica surface are investigated via molecular dynamics simulations. We observe a dense, almost fiat ethanol bilayer formed in the vicinity of the mica...The structural and dynamic properties of nanoscale ethanol film on a mica surface are investigated via molecular dynamics simulations. We observe a dense, almost fiat ethanol bilayer formed in the vicinity of the mica surface, with the hydrophobic alkyl groups pointing outward from the surface. Remarkably, such ethanol bilayer is laterally well-ordered with patterned adsorption sites. Each ethanol molecule in the first layer donates one hydrogen bond to the surface basal oxygen atoms and accepts one hydrogen bond from that in the second layer. The ethanol molecules within the bilayer exhibit constrained lateral mobility and delayed dynamics as compared with bulk ethanol, whereas those on top of the bilayer have bulk-like characteristics.展开更多
文摘环境中与日俱增的有机污染物严重危害着生态环境和人体健康.先前研究往往忽视了有机污染物分子团簇(molecular cluster of organic contaminants,MCOCs)的影响,而MCOCs的形成可能改变有机污染物的理化特性,进而影响其环境行为和归趋.分子结构特性及环境条件决定了有机污染物的赋存状态(分子态、离子态、团簇态和沉淀态),也进一步决定了其环境行为和风险.比如,MCOCs相较于其它赋存状态可能更有利于其被快速吸附,但也可能由于其尺寸较大而限制了在孔隙内的活动.文章综述了决定有机污染物(多环芳烃、邻苯二甲酸酯、其它有机污染物)赋存状态的因素以及它们的环境行为和环境效应,并总结了MCOCs形成的普遍性和显著性,着重强调了它们的环境行为、效应及潜在的环境风险,旨在为有机污染物的环境行为和效应研究以及其污染控制策略的形成提供理论支撑.
文摘Wheat ( Triticum aestivum L.) plants were grown under ambient and doubled_CO 2(plus 350 μL/L) concentration in cylindrical open_top chamber to examine their effects on the ultrastructure, supramolecular architecture, absorption spectrum and low temperature (77 K) fluorescence emission spectrum of the chloroplasts from wheat leaves. The results were briefly summarized as follows: (1) The wheat leaves possessed normally developed chloroplasts with intact grana and stroma thylakoid membranes; The grana intertwined with stroma thylakoid membranes and increased slightly in stacking degree and the width of granum, in spite of more accumulated starch grains within the chloroplasts than those in control; (2) The particle density in the stacked region of the endoplasmic fracture face (EFs) and protoplasmic fracture face (PFs) and in the unstacked region the endoplasmic fracture face (EFu) and the protoplasmic fracture face (PFu) was significantly higher than that of control. Furthermore, in some cases many more particles on EFs faces of thylakoid membranes appeared as a paracrystalline particle array; (3) The variations in the structure of chloroplasts were consistent with the absorption spectra and the low temperature (77 K) fluorescence emission spectra of the chloroplasts developed under the doubled_CO 2 concentration. Results indicate that the capability of light energy absorption of chloroplasts and regulative capability of excitation energy distribution between PSⅡ and PSⅠ were raised by doubled_CO 2 concentration. This is very favorable for final productivity of wheat.
基金National Basic Research Program (973) of China ( 2009CB118701)National Natural Scientific Foundation of China (30871940, 30671615)
文摘Viral nonstructural proteins in both enveloped and non-enveloped viruses play important roles in viral replication. Protein NS38 of Grass carp reovirus (GCRV), has been deduced to be a non-structural protein, and, consistent with other reoviruses, is considered to cooperate with the NS80 protein in viral particle assembly. To investigate the molecular basis of the role of NS38, a complete protein was expressed in E.coli for the first time. It was found that there is a better expression of NS38 induced with IPTG at 28 ℃ rather than 37 ℃. In addition, the antiserum of NS38 prepared with purified fusion protein and injected into rabbit could be used for detecting NS38 protein expression in GCRV infected cell lysate, while there is not any reaction crossed with purified virus particle, confirming NS38 is not a component of the viral structural protein. The result reported in this study will provide evidence for further viral protein-protein and protein-RNA interaction in dsRNA viruses replication.
文摘Highly efficient synthesis methods have been developed and characteristics of nanometallocarbosilanes molecular structure were studied by the research team of GNIIChTEOS （State Research Institute for Chemistry and Technology of Organoelement Compounds）. Nanometallocarbosilanes were synthesized by thermal co-condensation of oligocarbosilanes and alkyl amides of refractory metals. Initial, intermediate and final products of side reactions were characterized by 1H, 13C, 29Si NMR （nuclear magnetic resonance）, IR （infra-red） spectroscopy, GPC （gel-penetrating chromatography）, TGA （thermal gravimetric analysis）, TEM （transmission electron microscopy）, SEM （scanning electron microscopy）, RES （X-ray phase analysis） and elemental analysis. The proposed synthesis method of nanometallocarbosilanes was lbund to produce fusable soluble organosilicon oligomers with homogeneous distribution of nanoscale （10-20 nm） metal particles in the oligomer matrix. A computational model of the group and elemental composition of nanometallocarbosilanes was developed; it was shown that they are molecular globules of near-spherical shape and rigid polycyclic structure. Thermochemical treatment of nanometallocarbosilanes leads to SiC-nanoceramics （a high yield of up to 75-80 mass%） modified by metal nanoparticles （20-30 nm） contributing to its stabilization. The application of preceramic oxygen-free nanometallocarbosilanes will make it possible to advance in solving the problem of ceramic composite materials with long-term resistance at temperatures above 1,500 ℃ in oxidizing environments.
基金Supported by DST-FIST Project.financial support from DST-FIST, Government of India
文摘The effect of terminal groups on the electron transport through metal-molecule-metal system has been investigated using nonequilibrium Green's function (NEGF) formalism combined with extended Huckel theory (EHT). Au-molecule-Au junctions are constructed with borazine and BCN unit structure as core molecule and sulphur (S), oxygen (O), selenium (Se) and cyano-group (CN) as terminal groups. The electron transport characteristics of the borazine and BCN molecular systems are analyzed through the transmission spectra and the current-voltage curve. The results demonstrate that the terminal groups modifying the transport behaviors of these systems in a controlled way. Our result shows that, selenium is the best linker to couple borazine to Au electrode and oxygen is the best one to couple BCN to Au electrode. Furthermore, the results of borazine systems are compared with that of BCN molecular systems and are discussed. Simulation results show that the conductance through BCN molecular systems is four times larger than the borazine molecular systems. Negative differential resistance behavior is observed with borazine-CN system and the saturation feature appears in BCN systems.
基金Supported by Grants from Chinese Academy of Sciences,the National Natural Science Foundation of China under Grant No. 10825520National Basic Research Program of China under Grant No. 2007CB936000China Postdoctoral Science Foundation under Grant No. 20100480645
文摘The structural and dynamic properties of nanoscale ethanol film on a mica surface are investigated via molecular dynamics simulations. We observe a dense, almost fiat ethanol bilayer formed in the vicinity of the mica surface, with the hydrophobic alkyl groups pointing outward from the surface. Remarkably, such ethanol bilayer is laterally well-ordered with patterned adsorption sites. Each ethanol molecule in the first layer donates one hydrogen bond to the surface basal oxygen atoms and accepts one hydrogen bond from that in the second layer. The ethanol molecules within the bilayer exhibit constrained lateral mobility and delayed dynamics as compared with bulk ethanol, whereas those on top of the bilayer have bulk-like characteristics.
