Objective: To observe whether there is evidence for vascular channel formation by osteosarcoma cellsin vitro and to illustrate mechanism of vasculogenic mimicry in osteosarcoma.Methods: Osteosarcoma cell lines (U-2OS)...Objective: To observe whether there is evidence for vascular channel formation by osteosarcoma cellsin vitro and to illustrate mechanism of vasculogenic mimicry in osteosarcoma.Methods: Osteosarcoma cell lines (U-2OS) were tested for their ability to form tubular networks in three-dimensional culture containing type I collagen. The structures of the tubular networks were observed under a phase contrast microscope and an electron microscope.Results: Observation under light microscopy and electron microscopy showed that high aggressive osteosarcoma cells line (U-2OS) formed networks containing channels when grown in three-dimensional culture containing type I collagen in the absence of endothelial cells or fibroblasts.Conclusion: These observations strongly suggest that aggressive osteosarcoma cells may generate vascular channels that facilitate tumor perfusion independent of tumor angiogenesis and have the ability of vasculogenic mimicry. Key words osteosarcoma cells line - vasculogenesis mimicry - angiogenesis - 3-dimensional cultures This study was supported in part by the National Natural Sciences Foundation of China (No. 30271314).展开更多
The dynamic equivalent continuum modeling method of the mast which is based on energy equivalency principle was investigated. And three kinds of mast dynamic model were established, which were equivalent continuum mod...The dynamic equivalent continuum modeling method of the mast which is based on energy equivalency principle was investigated. And three kinds of mast dynamic model were established, which were equivalent continuum model, finite element model and simulation model, respectively. The mast frequencies and mode shapes were calculated by these models and compared with each other. The error between the equivalent continuum model and the finite element model is less than 5% when the mast length is longer. Dynamic responses of the mast with different lengths are tested, the mode frequencies and mode shapes are compared with finite element model. The mode shapes match well with each other, while the frequencies tested by experiments are lower than the results of the finite element model, which reflects the joints lower the mast stiffness. The nonlinear dynamic characteristics are presented in the dynamic responses of the mast under different excitation force levels. The joint nonlinearities in the deployable mast are identified as nonlinear hysteresis contributed by the coulomb friction which soften the mast stiffness and lower the mast frequencies.展开更多
AIM: To assess the three polymorphJsm regions within cytotoxic T-lymphocyte antigen 4 (CTLA-4) gene, a C/T base exchange in the promoter region-318 (CTLA-4 -318C/T), an A/G substitution in the exon 1 position 49 ...AIM: To assess the three polymorphJsm regions within cytotoxic T-lymphocyte antigen 4 (CTLA-4) gene, a C/T base exchange in the promoter region-318 (CTLA-4 -318C/T), an A/G substitution in the exon 1 position 49 (CTLA-4 49A/G), a T/C substitution in 1172 (CTLA-4 -1172T/C) in patients with chronic hepatitis B. METHODS: Fifty-one patients with chronic hepatitis B virus infection and 150 healthy subjects were recruited sequentially as they presented to the hepatic clinic. Classification of chronic hepatitis B virus (HBV)-infected patients was as asymptomatic carrier state (26 patients) and chronic hepatitis B (25 patients). Genomic DNA was isolated from anti-coagulated peripheral blood Bully coat using Miller's salting-out method. The presence of the CTLA-4 gene polymorphisms was determined using polymerase chain reaction amplification refractory mutation system (ARMS). RESULTS: We observed a significant association between -318 genotypes frequency (T+C-, T+C+, T-C+) and susceptibility to chronic hepatitis B (P=0.012, OR=0.49, 95%CI: 0.206-1.162). However, we did not observe a significant association for +49 genotype frequency (T+C+, T+C- T-C+) and -1172 genotype frequency (C+T+, T+C- C+T-) and state of disease. CONCLUSION: Our results suggest that CTLA-4 gene polymorphisms may partially be involved in the susceptibility to chronic hepatitis B.展开更多
Using the "pseudo-invariant eigen-operator" method we find the energy-gap of the Jaynes-Cummings Hamiltonian model of an atom-cavity system. This model takes the atomic centre-of-mass motion into account. The supers...Using the "pseudo-invariant eigen-operator" method we find the energy-gap of the Jaynes-Cummings Hamiltonian model of an atom-cavity system. This model takes the atomic centre-of-mass motion into account. The supersymmetric structure is involved in the Hamiltonian of an atom-cavity system. By selecting suitable supersymmettic generators and using supersymmetrie transformation the Hamiltonian is diagonalized and energy eigenvectors are obtained.展开更多
We adopt a dynamical algebraic method to study a four-level excited-doublet atom model and obtain the explicit expressions of the time-evolution operator and the density operator for the system. The nonclassical effec...We adopt a dynamical algebraic method to study a four-level excited-doublet atom model and obtain the explicit expressions of the time-evolution operator and the density operator for the system. The nonclassical effects of the system, such as collapses and revivals of the atomic inversion and squeezing of the radiation field, are also discussed.展开更多
Objective To identify the possible association between C(-106)T polymorphism of the aldose reductase (ALR) gene and diabetic retinopathy (DR) in a cohort of Chinese patients with type 2 diabetes mellitus (T2DM...Objective To identify the possible association between C(-106)T polymorphism of the aldose reductase (ALR) gene and diabetic retinopathy (DR) in a cohort of Chinese patients with type 2 diabetes mellitus (T2DM). Methods From November 2009 to September 2010, patients with T2DM were recruited and assigned to DR group or diabetic without retinopathy (DWR) group according to the duration of diabetes and the grading of 7-field fundus color photographs of both eyes. Genotypes of the C(-106)T polymorphism (rs759853) in ALR gene were analyzed using the MassARRAY genotyping system and an association study was performed. Results A total of 268 T2DM patients (129 in the DR group and 139 in the DWR group) were included in this study. No statistically significant differences were observed between the 2 groups in the age of diabetes onset (P=0.10) and gender (P=0.78). The success rate of genotyping for the study subjects was 99.6% (267/268), with one case of failure in the DR group. The frequencies of the T allele in the C(-106)T polymorphism were 16.0% (41/256) in the DR group and 19.4% (54/278) in the DWR group (P=0.36). There was no signit^cant difference in the C(-106)T genotypes between the 2 groups (P=0.40). Compared with the wild-type genotype, odds ratio (OR) for the risk of DR was 0.7 (95% CI, 0.38-1.3) for the heterozygous CT genotype and 0.76 (95% CI, 0.18-3.25) for the homozygous TT genotype. The risk of DR was positively associated with microalbuminuria (OR=4.61; 95% CI, 2.34-9.05) and insulin therapy (OR=3.43; 95% CI, 1.94-6.09). Conclusions Microalbuminuria and insulin therapy are associated with the risk of DR in Chinese patients with T2DM. C(-106)T polymorphism of the ALR gene may not be significantly associated with DR in Chinese patients with T2DM.展开更多
In the two-parameter corresponding states principle(CSP), the critical compressibility factors of the fluid under study(called 'a' fluid) and the reference fluid(called 'o' fluid) must be identical. Th...In the two-parameter corresponding states principle(CSP), the critical compressibility factors of the fluid under study(called 'a' fluid) and the reference fluid(called 'o' fluid) must be identical. This is not generally observed in nature. To overcome this limitation, a perfect shape factor CSP is proposed in which the compressibility factors of 'a' and 'o' fluids are corresponded perfectly by introducing a new pressure shape factor 8. Using methane as the 'o' fluid, the shape factors of many fluids are calculated from PVT properties at saturation state and the second virial coefficients. Models are also formulated for the shape factors with the assumption of is a function of temperature and volume while 6 and 5 are temperature dependent only. The models described the shape factors satisfactorily in whole region including vapor, liquid and their co-existing phases. The perfect shape factor CSP could be applied for both polar and non-polar fluids.展开更多
Four wheat (Triticum aestivum L.) cultivars 711, PBW343, 3765 and WH542 were screened for studying variations in glycinebetaine (GB) content and plant dry mass under 100 mmol L-1 NaCl stress. A tolerance index was...Four wheat (Triticum aestivum L.) cultivars 711, PBW343, 3765 and WH542 were screened for studying variations in glycinebetaine (GB) content and plant dry mass under 100 mmol L-1 NaCl stress. A tolerance index was calculated using plant dry mass data to select salt-tolerant and salt-sensitive types and find association between tolerance index and GB content. Tolerance index has been used as a good criterion to select the tolerant types under high salinity stress. Further, physiological differences in salt-tolerant cultivar 711 and salt-sensitive cultivar WH542 were examined. The salt-tolerant cultivar exhibited greater CB content, which was found correlative with ethylene. The cultivar also showed higher nitrogen (N) content and nitrate reductase activity, reduced glutathione and higher redox state resulting in maximal protection of plant dry mass than the salt-sensitive type. Thus, the content of CB may be considered as important physiological criteria for selecting salt-tolerant wheat types.展开更多
Au nanoclusters (AuNCs) hold tremendous potential to be employed in a wide variety of biological applications. Despite the rapid development in the field of NCs synthesis, a comprehensive understanding of how cells ...Au nanoclusters (AuNCs) hold tremendous potential to be employed in a wide variety of biological applications. Despite the rapid development in the field of NCs synthesis, a comprehensive understanding of how cells interact with this class of ultra-small nanoparticles (〈2 nm) having defined sizes and surface chemistry, remains poorly understood. In this study, we show that the choice of the surface ligand used to protect AuNCs can significantly perturb cellular uptake and intracellular redox signaling. A panel of monodisperse, atomically precise AuNCs with different core Au atom number (i.e., Auls, Au18 and Au25) protected with either mercaptopropionic acid (MPA) or glutathione (GSH) capping agent were synthesized and their effects on the generation of intracellular reactive oxygen species (ROS), cytotoxicity and genotoxicity of the NCs were assessed. Both mitochondrial superoxide anion (O2^-) and cytoplasmic ROS were found to be higher in cells exposed to MPA but not GSH capped AuNCs. The unregulated state of intracellular ROS is correlated to the amount of internalized AuNCs. Interestingly, MPA-AuNCs induction of ROS level did not lead to any detrimental cellular effects such as cell death or DNA damage. Instead, it was observed that the increase in redox status corresponded to higher cellular metabolism and proliferative capacity. Our study illustrates that surface chemistry of AuNCs plays a pivotal role in affecting the biological outcomes and the new insights gained will be useful to form the basis of defining specific design rules to enable rational engineering of ultra-small complex nanostructures for biological applications.展开更多
Based on the Terrestrial Ecosystem Model(TEM 5.0), together with the data of climate(temperature, precipitation and solar radiation) and environment(grassland vegetation types, soil texture, altitude, longitude and la...Based on the Terrestrial Ecosystem Model(TEM 5.0), together with the data of climate(temperature, precipitation and solar radiation) and environment(grassland vegetation types, soil texture, altitude, longitude and latitude, and atmospheric CO2 concentration data), the spatiotemporal variations of carbon storage and density, and their controlling factors were discussed in this paper. The results indicated that:(1) the total carbon storage of China's grasslands with a total area of 394.93×104 km2 was 59.47 Pg C. Among them, there were 3.15 Pg C in vegetation and 56.32 Pg C in soil carbon. China's grasslands covering 7.0–11.3% of the total world's grassland area had 1.3–11.3% of the vegetation carbon and 9.7–22.5% of the soil carbon in the world grasslands. The total carbon storage increased from 59.13 to 60.16 Pg C during 1961–2013 with an increasing rate of 19.4 Tg C yr^(-1).(2) The grasslands in the Qinghai-Tibetan Plateau contributed most to the total carbon storage during 1961–2013, accounting for 63.2% of the total grassland carbon storage, followed by Xinjiang grasslands(15.8%) and Inner Mongolia grasslands(11.1%).(3) The vegetation carbon storage showed an increasing trend, with the average annual growth rate of 9.62 Tg C yr^(-1) during 1961–2013, and temperature was the main determinant factor, explaining approximately 85% of its variation. The vegetation carbon storage showed an increasing trend in most grassland regions, however, a decreasing trend in the central grassland in the southern China, the western and central parts of the Inner Mongolian grasslands as well as some parts on the Qinghai-Tibetan Plateau. The soil carbon storage showed a significantly increasing trend with a rate of 7.96 Tg C yr^(-1), which resulted from the interaction of more precipitation and low temperature in the 1980 s and 1990 s. Among them, precipitation was the main determinant factor of increasing soil carbon increases of China's grasslands.展开更多
Herein symmetrical four-legged suspension lunar lander was used as the research object, the six-degree-of-freedom dynamic model was built and the model of the lunar soil friction coefficient was improved. For the low-...Herein symmetrical four-legged suspension lunar lander was used as the research object, the six-degree-of-freedom dynamic model was built and the model of the lunar soil friction coefficient was improved. For the low-gravity simulation on objects outside earth for future work, the law of dynamic similarity for detectors was deduced. A new method was proposed for simulating the low-gravity field on the surface of objects outside earth, which was achieved by changing initial conditions of the landing by the probe and by subsequent treatment of experimental data. The prototype tested the limitation of this method was verified. It is shown that the prototypes of detectors can be used in detectors low-gravity simulation test with this method, and equipments are simple and operationally effective. This method can be used for later lunar exploration, and low-gravity simulations on extraterrestrial objects.展开更多
A model for the morphological evolution of a void under thermal and mechanical loads is established, and the thermodynamics potential of the model is given based on energy principle. Thus, the path and the bifurcation...A model for the morphological evolution of a void under thermal and mechanical loads is established, and the thermodynamics potential of the model is given based on energy principle. Thus, the path and the bifurcation condition of the morphological evolution of the void are described, which gives some insight into the reliability of the interconnect under combined thermal and mechanical loads.展开更多
Aboveground biomass in grasslands of the Qinghai-Tibet Plateau has displayed an overall increasing trend during 2003–2016, which is profoundly influenced by climate change. However, the responses of different biomes ...Aboveground biomass in grasslands of the Qinghai-Tibet Plateau has displayed an overall increasing trend during 2003–2016, which is profoundly influenced by climate change. However, the responses of different biomes show large discrepancies, in both size and magnitude. By applying partial least squares regression, we calculated the correlation between peak aboveground biomass and mean monthly temperature and monthly total precipitation in the preceding 12 months for three different grassland types(alpine steppe, alpine meadow, and temperate steppe) on the central and eastern Qinghai-Tibet Plateau. The results showed that mean temperature in most preceding months was positively correlated with peak aboveground biomass of alpine meadow and alpine steppe, while mean temperature in the preceding October and February to June was significantly negatively correlated with peak aboveground biomass of temperate steppe. Precipitation in all months had a promoting effect on biomass of alpine meadow, but its correlations with biomass of alpine steppe and temperate steppe were inconsistent. It is worth noting that, in a warmer, wetter climate, peak aboveground biomass of alpine meadow would increase more than that of alpine steppe, while that of temperate steppe would decrease significantly, providing support for the hypothesis of conservative growth strategies by vegetation in stressed ecosystems.展开更多
The more oxidized mantle peridotites above subducting slabs than stable continental areas have been attributed to the infiltration of some oxidizing fluids released from the subducting slabs. However, knowledge for th...The more oxidized mantle peridotites above subducting slabs than stable continental areas have been attributed to the infiltration of some oxidizing fluids released from the subducting slabs. However, knowledge for the redox states of the slabs itself is very limited. Until now, few oxybarometers can be directly used to constrain the redox states of the subducting slabs.The rutile-ilmenite oxybarometer was proposed and successfully applied to constrain the oxygen fugacity of mantle assemblages.However, its application to rocks equilibrated at crustal P-T conditions has been hampered by some uncertainties in an early solid solution model of ilmenite. With a newly-released solid solution model for the ilmenite, we have conducted high-P experiments(at 3 and 5 GPa, and 900–1300°C) to test the accuracy of this oxybarometer. The experiments were performed with their oxygen fugacities controlled by the CCO buffer(i.e., C+O_2=CO_2). We demonstrated that the oxygen fugacities calculated for our high-P experimental products by using the rutile-ilmenite oxybarometer were in excellent agreement with the fO_2 dictated by the CCO buffer, suggesting a wide applicability of this oxybarometer to crust rocks. As examples, the rutile-ilmenite oxybarometer has been used to constrain the oxygen fugacities of some metamorphic rocks such as eclogite, granulite and amphibolite usually observed from the subduction zones.展开更多
In this paper we have studied the dynamical evolution of Shannon information entropies in position and momentum spaces for two classes of(nonstationary) atom-field entangled states,which are obtained via the JaynesC...In this paper we have studied the dynamical evolution of Shannon information entropies in position and momentum spaces for two classes of(nonstationary) atom-field entangled states,which are obtained via the JaynesCummings model and its generalization.We have focused on the interaction between two- and(1)-type three-level atoms with the single-mode quantized field.The three-dimensional plots of entropy densities in position and momentum spaces are presented versus corresponding coordinates and time,numerically.It is observed that for particular values of the parameters of the systems,the entropy squeezing in position space occurs.Finally,we have shown that the well-known BBM(Beckner,Bialynicki-Birola and Mycielsky) inequality,which is a stronger statement of the Heisenberg uncertainty relation,is properly satisfied.展开更多
基金This study was supported in part by the National Natural Sciences Foundation of China(No.30271314).
文摘Objective: To observe whether there is evidence for vascular channel formation by osteosarcoma cellsin vitro and to illustrate mechanism of vasculogenic mimicry in osteosarcoma.Methods: Osteosarcoma cell lines (U-2OS) were tested for their ability to form tubular networks in three-dimensional culture containing type I collagen. The structures of the tubular networks were observed under a phase contrast microscope and an electron microscope.Results: Observation under light microscopy and electron microscopy showed that high aggressive osteosarcoma cells line (U-2OS) formed networks containing channels when grown in three-dimensional culture containing type I collagen in the absence of endothelial cells or fibroblasts.Conclusion: These observations strongly suggest that aggressive osteosarcoma cells may generate vascular channels that facilitate tumor perfusion independent of tumor angiogenesis and have the ability of vasculogenic mimicry. Key words osteosarcoma cells line - vasculogenesis mimicry - angiogenesis - 3-dimensional cultures This study was supported in part by the National Natural Sciences Foundation of China (No. 30271314).
基金Projects(50935002, 11002039) supported by the National Natural Science Foundation of ChinaProject(HIT.KLOF.2009062) supported by Key Laboratory Opening Funding of Aerospace Mechanism and Control Technology,Chinasupport by "111 Project" (Grant No.B07018)
文摘The dynamic equivalent continuum modeling method of the mast which is based on energy equivalency principle was investigated. And three kinds of mast dynamic model were established, which were equivalent continuum model, finite element model and simulation model, respectively. The mast frequencies and mode shapes were calculated by these models and compared with each other. The error between the equivalent continuum model and the finite element model is less than 5% when the mast length is longer. Dynamic responses of the mast with different lengths are tested, the mode frequencies and mode shapes are compared with finite element model. The mode shapes match well with each other, while the frequencies tested by experiments are lower than the results of the finite element model, which reflects the joints lower the mast stiffness. The nonlinear dynamic characteristics are presented in the dynamic responses of the mast under different excitation force levels. The joint nonlinearities in the deployable mast are identified as nonlinear hysteresis contributed by the coulomb friction which soften the mast stiffness and lower the mast frequencies.
文摘AIM: To assess the three polymorphJsm regions within cytotoxic T-lymphocyte antigen 4 (CTLA-4) gene, a C/T base exchange in the promoter region-318 (CTLA-4 -318C/T), an A/G substitution in the exon 1 position 49 (CTLA-4 49A/G), a T/C substitution in 1172 (CTLA-4 -1172T/C) in patients with chronic hepatitis B. METHODS: Fifty-one patients with chronic hepatitis B virus infection and 150 healthy subjects were recruited sequentially as they presented to the hepatic clinic. Classification of chronic hepatitis B virus (HBV)-infected patients was as asymptomatic carrier state (26 patients) and chronic hepatitis B (25 patients). Genomic DNA was isolated from anti-coagulated peripheral blood Bully coat using Miller's salting-out method. The presence of the CTLA-4 gene polymorphisms was determined using polymerase chain reaction amplification refractory mutation system (ARMS). RESULTS: We observed a significant association between -318 genotypes frequency (T+C-, T+C+, T-C+) and susceptibility to chronic hepatitis B (P=0.012, OR=0.49, 95%CI: 0.206-1.162). However, we did not observe a significant association for +49 genotype frequency (T+C+, T+C- T-C+) and -1172 genotype frequency (C+T+, T+C- C+T-) and state of disease. CONCLUSION: Our results suggest that CTLA-4 gene polymorphisms may partially be involved in the susceptibility to chronic hepatitis B.
基金The project supported by the President Foundation of the Chinese Academy of Sciences and the research fund provided by Graduate School of University of Science and Technology of China
文摘Using the "pseudo-invariant eigen-operator" method we find the energy-gap of the Jaynes-Cummings Hamiltonian model of an atom-cavity system. This model takes the atomic centre-of-mass motion into account. The supersymmetric structure is involved in the Hamiltonian of an atom-cavity system. By selecting suitable supersymmettic generators and using supersymmetrie transformation the Hamiltonian is diagonalized and energy eigenvectors are obtained.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10174066 and 10275055
文摘We adopt a dynamical algebraic method to study a four-level excited-doublet atom model and obtain the explicit expressions of the time-evolution operator and the density operator for the system. The nonclassical effects of the system, such as collapses and revivals of the atomic inversion and squeezing of the radiation field, are also discussed.
基金Supported by the National Basic Research Program of China(973 Program,2007CB512201)the Beijing Municipal Health Bureau Grant(2009208)the Beijing Natural Science Foundation(7131007)
文摘Objective To identify the possible association between C(-106)T polymorphism of the aldose reductase (ALR) gene and diabetic retinopathy (DR) in a cohort of Chinese patients with type 2 diabetes mellitus (T2DM). Methods From November 2009 to September 2010, patients with T2DM were recruited and assigned to DR group or diabetic without retinopathy (DWR) group according to the duration of diabetes and the grading of 7-field fundus color photographs of both eyes. Genotypes of the C(-106)T polymorphism (rs759853) in ALR gene were analyzed using the MassARRAY genotyping system and an association study was performed. Results A total of 268 T2DM patients (129 in the DR group and 139 in the DWR group) were included in this study. No statistically significant differences were observed between the 2 groups in the age of diabetes onset (P=0.10) and gender (P=0.78). The success rate of genotyping for the study subjects was 99.6% (267/268), with one case of failure in the DR group. The frequencies of the T allele in the C(-106)T polymorphism were 16.0% (41/256) in the DR group and 19.4% (54/278) in the DWR group (P=0.36). There was no signit^cant difference in the C(-106)T genotypes between the 2 groups (P=0.40). Compared with the wild-type genotype, odds ratio (OR) for the risk of DR was 0.7 (95% CI, 0.38-1.3) for the heterozygous CT genotype and 0.76 (95% CI, 0.18-3.25) for the homozygous TT genotype. The risk of DR was positively associated with microalbuminuria (OR=4.61; 95% CI, 2.34-9.05) and insulin therapy (OR=3.43; 95% CI, 1.94-6.09). Conclusions Microalbuminuria and insulin therapy are associated with the risk of DR in Chinese patients with T2DM. C(-106)T polymorphism of the ALR gene may not be significantly associated with DR in Chinese patients with T2DM.
基金Supported by the National Natural Science Foundation of China (No.29876033), the Doctoral Foundation of Ministry of Education of China (No. 98033508) and the Zhejiang Natural Science Foundation (No. 298030).
文摘In the two-parameter corresponding states principle(CSP), the critical compressibility factors of the fluid under study(called 'a' fluid) and the reference fluid(called 'o' fluid) must be identical. This is not generally observed in nature. To overcome this limitation, a perfect shape factor CSP is proposed in which the compressibility factors of 'a' and 'o' fluids are corresponded perfectly by introducing a new pressure shape factor 8. Using methane as the 'o' fluid, the shape factors of many fluids are calculated from PVT properties at saturation state and the second virial coefficients. Models are also formulated for the shape factors with the assumption of is a function of temperature and volume while 6 and 5 are temperature dependent only. The models described the shape factors satisfactorily in whole region including vapor, liquid and their co-existing phases. The perfect shape factor CSP could be applied for both polar and non-polar fluids.
文摘Four wheat (Triticum aestivum L.) cultivars 711, PBW343, 3765 and WH542 were screened for studying variations in glycinebetaine (GB) content and plant dry mass under 100 mmol L-1 NaCl stress. A tolerance index was calculated using plant dry mass data to select salt-tolerant and salt-sensitive types and find association between tolerance index and GB content. Tolerance index has been used as a good criterion to select the tolerant types under high salinity stress. Further, physiological differences in salt-tolerant cultivar 711 and salt-sensitive cultivar WH542 were examined. The salt-tolerant cultivar exhibited greater CB content, which was found correlative with ethylene. The cultivar also showed higher nitrogen (N) content and nitrate reductase activity, reduced glutathione and higher redox state resulting in maximal protection of plant dry mass than the salt-sensitive type. Thus, the content of CB may be considered as important physiological criteria for selecting salt-tolerant wheat types.
文摘Au nanoclusters (AuNCs) hold tremendous potential to be employed in a wide variety of biological applications. Despite the rapid development in the field of NCs synthesis, a comprehensive understanding of how cells interact with this class of ultra-small nanoparticles (〈2 nm) having defined sizes and surface chemistry, remains poorly understood. In this study, we show that the choice of the surface ligand used to protect AuNCs can significantly perturb cellular uptake and intracellular redox signaling. A panel of monodisperse, atomically precise AuNCs with different core Au atom number (i.e., Auls, Au18 and Au25) protected with either mercaptopropionic acid (MPA) or glutathione (GSH) capping agent were synthesized and their effects on the generation of intracellular reactive oxygen species (ROS), cytotoxicity and genotoxicity of the NCs were assessed. Both mitochondrial superoxide anion (O2^-) and cytoplasmic ROS were found to be higher in cells exposed to MPA but not GSH capped AuNCs. The unregulated state of intracellular ROS is correlated to the amount of internalized AuNCs. Interestingly, MPA-AuNCs induction of ROS level did not lead to any detrimental cellular effects such as cell death or DNA damage. Instead, it was observed that the increase in redox status corresponded to higher cellular metabolism and proliferative capacity. Our study illustrates that surface chemistry of AuNCs plays a pivotal role in affecting the biological outcomes and the new insights gained will be useful to form the basis of defining specific design rules to enable rational engineering of ultra-small complex nanostructures for biological applications.
基金supported by the Strategic Priority Research Program–Climate Change:Carbon Budget and Related Issues of the Chinese Academy of Sciences(Grant No.XDA-05050408)
文摘Based on the Terrestrial Ecosystem Model(TEM 5.0), together with the data of climate(temperature, precipitation and solar radiation) and environment(grassland vegetation types, soil texture, altitude, longitude and latitude, and atmospheric CO2 concentration data), the spatiotemporal variations of carbon storage and density, and their controlling factors were discussed in this paper. The results indicated that:(1) the total carbon storage of China's grasslands with a total area of 394.93×104 km2 was 59.47 Pg C. Among them, there were 3.15 Pg C in vegetation and 56.32 Pg C in soil carbon. China's grasslands covering 7.0–11.3% of the total world's grassland area had 1.3–11.3% of the vegetation carbon and 9.7–22.5% of the soil carbon in the world grasslands. The total carbon storage increased from 59.13 to 60.16 Pg C during 1961–2013 with an increasing rate of 19.4 Tg C yr^(-1).(2) The grasslands in the Qinghai-Tibetan Plateau contributed most to the total carbon storage during 1961–2013, accounting for 63.2% of the total grassland carbon storage, followed by Xinjiang grasslands(15.8%) and Inner Mongolia grasslands(11.1%).(3) The vegetation carbon storage showed an increasing trend, with the average annual growth rate of 9.62 Tg C yr^(-1) during 1961–2013, and temperature was the main determinant factor, explaining approximately 85% of its variation. The vegetation carbon storage showed an increasing trend in most grassland regions, however, a decreasing trend in the central grassland in the southern China, the western and central parts of the Inner Mongolian grasslands as well as some parts on the Qinghai-Tibetan Plateau. The soil carbon storage showed a significantly increasing trend with a rate of 7.96 Tg C yr^(-1), which resulted from the interaction of more precipitation and low temperature in the 1980 s and 1990 s. Among them, precipitation was the main determinant factor of increasing soil carbon increases of China's grasslands.
基金supported by the National Natural Science Foundation of China(Grant No.51105196)Natural Science Foundation of Jiangsu Province(Grant No.BK2011733)
文摘Herein symmetrical four-legged suspension lunar lander was used as the research object, the six-degree-of-freedom dynamic model was built and the model of the lunar soil friction coefficient was improved. For the low-gravity simulation on objects outside earth for future work, the law of dynamic similarity for detectors was deduced. A new method was proposed for simulating the low-gravity field on the surface of objects outside earth, which was achieved by changing initial conditions of the landing by the probe and by subsequent treatment of experimental data. The prototype tested the limitation of this method was verified. It is shown that the prototypes of detectors can be used in detectors low-gravity simulation test with this method, and equipments are simple and operationally effective. This method can be used for later lunar exploration, and low-gravity simulations on extraterrestrial objects.
基金the National Natural Science Foundation of China(Nos.10602034,10572088)
文摘A model for the morphological evolution of a void under thermal and mechanical loads is established, and the thermodynamics potential of the model is given based on energy principle. Thus, the path and the bifurcation condition of the morphological evolution of the void are described, which gives some insight into the reliability of the interconnect under combined thermal and mechanical loads.
基金National Key R&D Program of China,No.2018YFA0606102National Natural Science Foundation of China,No.41771056National Key Technology Support Program,No.2012BAH31B02
文摘Aboveground biomass in grasslands of the Qinghai-Tibet Plateau has displayed an overall increasing trend during 2003–2016, which is profoundly influenced by climate change. However, the responses of different biomes show large discrepancies, in both size and magnitude. By applying partial least squares regression, we calculated the correlation between peak aboveground biomass and mean monthly temperature and monthly total precipitation in the preceding 12 months for three different grassland types(alpine steppe, alpine meadow, and temperate steppe) on the central and eastern Qinghai-Tibet Plateau. The results showed that mean temperature in most preceding months was positively correlated with peak aboveground biomass of alpine meadow and alpine steppe, while mean temperature in the preceding October and February to June was significantly negatively correlated with peak aboveground biomass of temperate steppe. Precipitation in all months had a promoting effect on biomass of alpine meadow, but its correlations with biomass of alpine steppe and temperate steppe were inconsistent. It is worth noting that, in a warmer, wetter climate, peak aboveground biomass of alpine meadow would increase more than that of alpine steppe, while that of temperate steppe would decrease significantly, providing support for the hypothesis of conservative growth strategies by vegetation in stressed ecosystems.
基金supported by the National Natural Science Foundation of China(Grant Nos.41520104004&41502038)the China Postdoctoral Science Foundation(Grant No.2015M570009)
文摘The more oxidized mantle peridotites above subducting slabs than stable continental areas have been attributed to the infiltration of some oxidizing fluids released from the subducting slabs. However, knowledge for the redox states of the slabs itself is very limited. Until now, few oxybarometers can be directly used to constrain the redox states of the subducting slabs.The rutile-ilmenite oxybarometer was proposed and successfully applied to constrain the oxygen fugacity of mantle assemblages.However, its application to rocks equilibrated at crustal P-T conditions has been hampered by some uncertainties in an early solid solution model of ilmenite. With a newly-released solid solution model for the ilmenite, we have conducted high-P experiments(at 3 and 5 GPa, and 900–1300°C) to test the accuracy of this oxybarometer. The experiments were performed with their oxygen fugacities controlled by the CCO buffer(i.e., C+O_2=CO_2). We demonstrated that the oxygen fugacities calculated for our high-P experimental products by using the rutile-ilmenite oxybarometer were in excellent agreement with the fO_2 dictated by the CCO buffer, suggesting a wide applicability of this oxybarometer to crust rocks. As examples, the rutile-ilmenite oxybarometer has been used to constrain the oxygen fugacities of some metamorphic rocks such as eclogite, granulite and amphibolite usually observed from the subduction zones.
文摘In this paper we have studied the dynamical evolution of Shannon information entropies in position and momentum spaces for two classes of(nonstationary) atom-field entangled states,which are obtained via the JaynesCummings model and its generalization.We have focused on the interaction between two- and(1)-type three-level atoms with the single-mode quantized field.The three-dimensional plots of entropy densities in position and momentum spaces are presented versus corresponding coordinates and time,numerically.It is observed that for particular values of the parameters of the systems,the entropy squeezing in position space occurs.Finally,we have shown that the well-known BBM(Beckner,Bialynicki-Birola and Mycielsky) inequality,which is a stronger statement of the Heisenberg uncertainty relation,is properly satisfied.