This paper introduces a novel approach for parameter sensitivity evaluation and efficient slope reliability analysis based on quantile-based first-order second-moment method(QFOSM).The core principles of the QFOSM are...This paper introduces a novel approach for parameter sensitivity evaluation and efficient slope reliability analysis based on quantile-based first-order second-moment method(QFOSM).The core principles of the QFOSM are elucidated geometrically from the perspective of expanding ellipsoids.Based on this geometric interpretation,the QFOSM is further extended to estimate sensitivity indices and assess the significance of various uncertain parameters involved in the slope system.The proposed method has the advantage of computational simplicity,akin to the conventional first-order second-moment method(FOSM),while providing estimation accuracy close to that of the first-order reliability method(FORM).Its performance is demonstrated with a numerical example and three slope examples.The results show that the proposed method can efficiently estimate the slope reliability and simultaneously evaluate the sensitivity of the uncertain parameters.The proposed method does not involve complex optimization or iteration required by the FORM.It can provide a valuable complement to the existing approximate reliability analysis methods,offering rapid sensitivity evaluation and slope reliability analysis.展开更多
An experimental investigation into the thermal conductivity of CF-SiC two-phase composite asphalt concrete is presented.The main objective of this study was to verify the possibility of using SiC powder instead of min...An experimental investigation into the thermal conductivity of CF-SiC two-phase composite asphalt concrete is presented.The main objective of this study was to verify the possibility of using SiC powder instead of mineral powder as the thermal conductive filler to prepare a new type of asphalt concrete and improve the efficiency of electrothermal snow and ice melting systems accordingly.The thermal conductivity of asphalt concrete prepared with different thermally conductive fillers was tested by a transient plane source method,and the related performances were measured.Then the temperature rise rate and surface temperature were studied through field heating tests.Finally,the actual ice melting efficiency of the thermally conductive asphalt concrete was evaluated using an effective electrothermal system.As shown by the experimental results,the composite made of SiC powder and carbon fiber has a high thermal conductivity.When SiC replaces mineral powder,the thermal conductivity of the asphalt mixture increases first and then decreases with the increase of carbon fiber content.In the present study,in particular,the thermal conductivity attained a peak when the carbon fiber content was 0.2%of the aggregate mass.展开更多
Effect of the heat treatment, including solution treatment （ST） and aging treatment （AT）, on the prior austenite grain （PAG） size, microstructure and mechanical properties of a precipitation hardening maraging s...Effect of the heat treatment, including solution treatment （ST） and aging treatment （AT）, on the prior austenite grain （PAG） size, microstructure and mechanical properties of a precipitation hardening maraging stainless steel was investigated. The results indicate that the relations between PAG size and yield strength （σy） under both ST and AT conditions obey the HalI-Petch relationship. Furthermore, after ST at 1050℃ for 1 h＋cryogenic treated （CT） at -70℃ for 8 h＋AT at 535℃ for 4 h, the tested steel showed its ultimate tensile strength （σb） and σy over 1900 MPa and 1750 MPa, respectively.展开更多
The 18%Ni alloy steels provide high strength and toughness, while age-hardenable or PH stainless steels also have good corrosion resistance. This paper focuses on an investigation of the heat treatment, mechanical pro...The 18%Ni alloy steels provide high strength and toughness, while age-hardenable or PH stainless steels also have good corrosion resistance. This paper focuses on an investigation of the heat treatment, mechanical properties and microstructural development of a new maraging stainless steel. It is reported that the heat treatment process should consist of solution treatment and cryogenic cooling to attain a fully martensitic structure, followed by aging at 813 K. This heat treatment resulted in an ultimate tensile strength of over 1900 MPa combined with good impact toughness. Transmission electron microscopy is used to show that, for the peak-aged condition （813 K/4 h）, nano-sized precipitates, e.g. Ni3Mo and/or R-phase, and a high density of dislocations were uniformly dispersed in the lath martensite matrix. The calculated yield strength, based on a revised Orowan mechanism, is in good agreement with the test data. The steel studied has an ultimate tensile strength over 1900 MPa, excellent fracture toughness, and good resistance against over-aging and relatively good corrosion resistance as well.展开更多
Temporal lobe epilepsy is associated with astrogliosis. Notchl signaling can induce astrogliosis in glioma. However, it remains unknown whether Notchl signaling is involved in the pathogenesis of epilepsy. This study ...Temporal lobe epilepsy is associated with astrogliosis. Notchl signaling can induce astrogliosis in glioma. However, it remains unknown whether Notchl signaling is involved in the pathogenesis of epilepsy. This study investigated the presence of Notchl, hairy and enhancer of split-l, and glial fibrillary acidic protein in the temporal neocortex and hippocampus of lithium-pilocar- pine-treated rats. The presence of Notchl and hairy and enhancer of split-1 was also explored in brain tissues of patients with intractable temporal lobe epilepsy. Quantitative electroencephalo- gram analysis and behavioral observations were used as auxiliary measures. Results revealed that the presence of Notchl, hairy and enhancer of split-l, and glial fibriUary acidic protein were en- hanced in status epilepticus and vehicle-treated spontaneous recurrent seizures rats, but remain unchanged in the following groups： control, absence of either status epilepticus or spontaneous recurrent seizures, and zileuton-treated spontaneous recurrent seizures. Compared with patient control cases, the presences of Notch1 and hairy and enhancer of split- 1 were upregulated in the temporal neocortex of patients with intractable temporal lobe epilepsy. Therefore, these results suggest that Notchl signaling may play an important role in the onset of temporal lobe epilepsy via astrogliosis. Furthermore, zileuton may be a potential therapeutic strategy for temporal lobe epilepsy by blocking Notchl signaling.展开更多
The emission wavelength of InGaN/GaN dot-in-wire LED can be tuned by modifying the nanowire diameter,but it causes mismatched angular distributions between blue,green,and red nanowires because of the excitation of dif...The emission wavelength of InGaN/GaN dot-in-wire LED can be tuned by modifying the nanowire diameter,but it causes mismatched angular distributions between blue,green,and red nanowires because of the excitation of different waveguide modes.Besides,the far-field radiation patterns and light extraction efficiency are typically calculated by center dipoles,which fails to provide accurate results.To address these issues,we first compare the simulation results between central dipole and dipole cloud with experimental data.Next,we calculate and analyze the display metrics for full-color nanowire LEDs by 3D dipole cloud.Finally,we achieve unnoticeable angular color shift within±20°viewing cone for augmented reality(AR)and virtual reality(VR)displays with an improved light extraction efficiency.展开更多
The use of carbon-fiber heating cables(CFHC)to achieve effective melting of snow and ice deposited on roads is a method used worldwide.In this study,tensile and compressive tests have been conducted to analyze the mech...The use of carbon-fiber heating cables(CFHC)to achieve effective melting of snow and ice deposited on roads is a method used worldwide.In this study,tensile and compressive tests have been conducted to analyze the mechan-ical properties of the CFHC and assess whether the maximum tensile and compressive strengths can meet the pavement design specifications.In order to study the aging produced by multiple cycles of heating and cooling,in particular,the CFHC was repeatedly heated in a cold chamber with an ambient temperature ranging between-20℃ and+40℃.Moreover,to evaluate how the strength of the pavement is affected by its presence,the CFHC was embedded at different depths and concrete blocks with different curing ages were subjected to relevant com-pression and splitting tensile tests.Numerical simulations based on the ANSYS software have also been performed and compared with the outcomes of the static loading tests.The results show that the CFHC embedded in the concrete does not affect the compressive splitting tensile strengths of the pavement.Overall,the CFHC meets the conditions required for continued use in road ice melting applications.展开更多
One of the key issues in international climate negotiations is the formulation of targets for emissions reduction for all countries based on the principle of ＂common but differentiated responsibilities＂. This formul...One of the key issues in international climate negotiations is the formulation of targets for emissions reduction for all countries based on the principle of ＂common but differentiated responsibilities＂. This formulation depends primarily on the quantitative attribution of the responsibilities of developed and developing countries for historical climate change. Using the Commuity Earth System Model（CESM）, we estimate the responsibilities of developed countries and developing countries for climatic change from 1850 to 2005 using their carbon dioxide, methane and nitrous oxide emissions. The results indicate that developed countries contribute approximately 53%–61%, and developing countries approximately 39%–47%, to the increase in global air temperature, upper oceanic warming, sea-ice reduction in the NH, and permafrost degradation. In addition, the spatial heterogeneity of these changes from 1850 to 2005 is primarily attributed to the emissions of greenhouse gases（GHGs）in developed countries. Although uncertainties remain in the climate model and the external forcings used, GHG emissions in developed countries are the major contributor to the observed climate system changes in the 20 th century.展开更多
The spewing of a screw conveyor easily occurs from the earth pressure balance(called EPB)shield in a water-rich sand stratum.This may lead to the collapse of the tunnel face and even serious subsidence of the ground s...The spewing of a screw conveyor easily occurs from the earth pressure balance(called EPB)shield in a water-rich sand stratum.This may lead to the collapse of the tunnel face and even serious subsidence of the ground surface.To understand the spewing mechanism of the shield screw conveyor and explore the critical hydraulic condition of soil spewing in a shield–soil chamber,a simplified theoretical model for the spewing of the screw conveyor was developed based on the equation of groundwater flow in the screw conveyor under turbulent state.Thus,coupling Darcy's law with Brinkman's equation,this model was implemented within the COMSOL Multiphysics framework.The underground water flow in the shield screw conveyor was simulated so as to obtain its velocity and flow rate.Numerical simulations show that the water pressure distribution is concentrated in the lower part of the soil chamber after the groundwater enters the soil chamber.When the groundwater enters the screw conveyor,its pressure gradually decreases along the direction of the screw conveyor.When the water flow reaches the stratum–shield interface,the flow velocity changes markedly:first increases and concentrates at the entrance of the lower soil chamber,plummets and stabilizes gradually,and increases again at the exit.The soil chamber and screw conveyor are significantly depressurized.It is also found that the soil permeability coefficient can be reduced to k<2.6×10^(−4)cm/s through appropriate soil improvement,which can effectively prevent the occurrence of spewing disasters.展开更多
For local radiotherapy, a three-dimensional(3D)conformal localized dose planning protocol has been established in this paper to develop a precise and reasonable dose plan. A precalculated 3D dose map for a single sour...For local radiotherapy, a three-dimensional(3D)conformal localized dose planning protocol has been established in this paper to develop a precise and reasonable dose plan. A precalculated 3D dose map for a single source is obtained using the Monte Carlo method, and the spatial dose maps are combined linearly to acquire the dose distribution. The dose distribution is visualized through the real-time display of the isodose line and isodose surface combined with the reconstructed 3D organ groups. By observing 3D dose coverage to the target volume and surrounding tissues, dose planning could be initiated with greater accuracy and precision to avoid dose dead zones and excessively high-dose levels, thus achieving the 3D conformal dose planning objective. Further research into the impact that blockages have on a needle trajectory can be conducted to optimize the insertion accuracy. A treatment planning system was developed to formulate and implement the 3D local treatment plan before the surgery,during the surgery, and after the surgery. Several experiments pertaining to both single-seed and multiple-seed dose distributions were conducted to verify the accuracy of the single-seed dose calculation module and 3D superposition dose calculation in the treatment planning system.展开更多
BACKGROUND： Pseudomonas aeruginosa mannose-sensitive hemagglutinin （PA-MSHA） parenteral injection is used as a broad-spectrum immunomodulator. It remains unclear whether PA-MSHA exhibits inhibitory effects on tumor...BACKGROUND： Pseudomonas aeruginosa mannose-sensitive hemagglutinin （PA-MSHA） parenteral injection is used as a broad-spectrum immunomodulator. It remains unclear whether PA-MSHA exhibits inhibitory effects on tumor cell growth. OBJECTIVE： To investigate inhibitory mechanisms of PA-MSHA-induced proliferation in rat C6 glioma cells in vitro. DESIGN, TIME AND SETTING： Comparative observation and in vitro experiments were performed at the Key Laboratory of Natural Medicine, Kunming Medical College, China from July 2008 to April 2009. MATERIALS： Rat C6 glioma cell line （Shanghai Institute of Cell Biology, Chinese Academy of Sciences, China） and PA-MSHA parenteral injection （Beijing Wanteer Bio-Pharmaceutical, China） were used in the present study. METHODS： Rat C6 glioma cells in logarithmic growth phase were harvested in vitro. Adherent monolayer cells were respectively treated with PA-MSHA at final colony-forming units （cfu） of 1 ×10^8 cfu/mL, 2 × 10^8 cfu/mL, 4 × 10^8 cfu/mL, 6 × 10^8 cfu/mL, and 8 ×10^8 cfu/mL following 24 hours of conventional culture. MAIN OUTCOME MEASURES： MTT colorimetric assay was utilized to determine the inhibitory rate of C6 glioma cells following treatment with various concentrations of PA-MSHA at different times. Cell apoptosis was detected by fluorescent microscopy following Hoechst 33258 staining. Flow cytometry was used to measure PA-MSHA effects on C6 cell cycle. RESULTS： Inhibitory rate of C6 glioma cells increased with prolonged time and increased dose. Hoechst 33258 staining revealed obvious morphological changes in apoptotic C6 glioma cells. Flow cytometry revealed hypodiploid peaks, Le., apoptotic peak, and the apoptotic rate in cells during S-phase significantly increased with increased concentrations in the experimental groups. CONCLUSION： With in vitro experiments, PA-MSHA preparations inhibited C6 glioma cell proliferation in a time- and dose-dependent manner. These mechanisms are likely associated with cell apoptosis induction and inhibition of the S phase.展开更多
The mid-infrared （MIR） luminescent properties of Dy3＋ ions in a new chalcohalide glass host, Ga2S3-Sb2S3-CsI, are investigated; and the suitability of the doped glass for MIR fiber lasers is evaluated. The Dy3＋-do...The mid-infrared （MIR） luminescent properties of Dy3＋ ions in a new chalcohalide glass host, Ga2S3-Sb2S3-CsI, are investigated; and the suitability of the doped glass for MIR fiber lasers is evaluated. The Dy3＋-doped chalcohalide glasses exhibit good thermal stability and intense MIR emissions around 2.96 μm and 4.41 μm. These emissions show quantum efficiencies （η） as high as ～ 60%, and have relatively large stimulated emission cross sections （σem）. The low phonon energy （～ 307 cm-1） of the host glass accounts for the intense MIR emissions, as well as the high η. These favorable thermal and emission properties make the Dy3＋-doped Ga2S3-Sb2S3-CsI glasses promising materials for MIR fiber amplifiers or lasers.展开更多
The concept,research content and direction of biological manufacturing were elaborated in this text. The biological manufacturing progress in China,application situation,development trend and existing problems were an...The concept,research content and direction of biological manufacturing were elaborated in this text. The biological manufacturing progress in China,application situation,development trend and existing problems were analyzed,and the prospect of the development of biological manufacturing was put forward,in order to provide reference and guidance for the manufacture of biological research and industrial development.展开更多
Regional climate change impact assessments are becoming increasingly important for developing adaptation strategies in an uncertain future with respect to hydro-climatic extremes. There are a number of Global Climate ...Regional climate change impact assessments are becoming increasingly important for developing adaptation strategies in an uncertain future with respect to hydro-climatic extremes. There are a number of Global Climate Models (GCMs) and emission scenarios providing predictions of future changes in climate. As a result, there is a level of uncertainty associated with the decision of which climate models to use for the assessment of climate change impacts. The IPCC has recommended using as many global climate model scenarios as possible;however, this approach may be impractical for regional assessments that are computationally demanding. Methods have been developed to select climate model scenarios, generally consisting of selecting a model with the highest skill (validation), creating an ensemble, or selecting one or more extremes. Validation methods limit analyses to models with higher skill in simulating historical climate, ensemble methods typically take multi model means, median, or percentiles, and extremes methods tend to use scenarios which bound the projected changes in precipitation and temperature. In this paper a quantile regression based validation method is developed and applied to generate a reduced set of GCM-scenarios to analyze daily maximum streamflow uncertainty in the Upper Thames River Basin, Canada, while extremes and percentile ensemble approaches are also used for comparison. Results indicate that the validation method was able to effectively rank and reduce the set of scenarios, while the extremes and percentile ensemble methods were found not to necessarily correlate well with the range of extreme flows for all calendar months and return periods.展开更多
Surface with well-defined components and structures possesses unique electronic,magnetic,optical and chemical properties.As a result,surface chemistry research plays a crucial role in various fields such as catalysis,...Surface with well-defined components and structures possesses unique electronic,magnetic,optical and chemical properties.As a result,surface chemistry research plays a crucial role in various fields such as catalysis,energy,materials,quantum,and microelectronics.Surface science mainly investigates the correspondence between surface property and functionality.Scanning probe microscopy(SPM)techniques are important tools to characterize surface properties because of the capability of atomic-scale imaging,spectroscopy and manipulation at the single-atom level.In this review,we summarize recent advances in surface electronic,magnetic and optical properties characterized mainly by SPM-based methods.We focus on elucidating theπ-magnetism in graphene-based nanostructures,construction of spin qubits on surfaces,topology properties of surface organic structures,STM-based light emission,tip-enhanced Raman spectroscopy and integration of machine learning in SPM studies.展开更多
Surface chemistry focuses on the investigation of the adsorption,migration,assembly,activation,reaction,and desorption of atoms and molecules at surfaces.Surface chemistry plays the pivotal roles in both fundamental s...Surface chemistry focuses on the investigation of the adsorption,migration,assembly,activation,reaction,and desorption of atoms and molecules at surfaces.Surface chemistry plays the pivotal roles in both fundamental science and applied technology.This review will summarize the recent progresses on surface assembly,synthesis and catalysis investigated mainly by scanning tunneling microscopy and atomic force microscopy.Surface assemblies of water and small biomolecules,construction of Sierpin′ski triangles and surface chirality are summarized.On-surface synthesis of conjugated carbo-and heterocycles and other kinds of carbon nanostructures are surveyed.Surface model catalysis,including single-atom catalysis and electrochemical catalysis,are discussed at the single-atom level.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52109144,52025094 and 52222905).
文摘This paper introduces a novel approach for parameter sensitivity evaluation and efficient slope reliability analysis based on quantile-based first-order second-moment method(QFOSM).The core principles of the QFOSM are elucidated geometrically from the perspective of expanding ellipsoids.Based on this geometric interpretation,the QFOSM is further extended to estimate sensitivity indices and assess the significance of various uncertain parameters involved in the slope system.The proposed method has the advantage of computational simplicity,akin to the conventional first-order second-moment method(FOSM),while providing estimation accuracy close to that of the first-order reliability method(FORM).Its performance is demonstrated with a numerical example and three slope examples.The results show that the proposed method can efficiently estimate the slope reliability and simultaneously evaluate the sensitivity of the uncertain parameters.The proposed method does not involve complex optimization or iteration required by the FORM.It can provide a valuable complement to the existing approximate reliability analysis methods,offering rapid sensitivity evaluation and slope reliability analysis.
基金the support of the Joint Funds of the Natural Science Foundation of Hubei Province(2022CFD130)the Technology Innovation Project of Hubei Province(Key Program,No.2023BEB010)+1 种基金the Key Research and Development Program of Hubei Province(No.2021BGD015)the Knowledge Innovation Project of Wuhan(No.2022010801010259).
文摘An experimental investigation into the thermal conductivity of CF-SiC two-phase composite asphalt concrete is presented.The main objective of this study was to verify the possibility of using SiC powder instead of mineral powder as the thermal conductive filler to prepare a new type of asphalt concrete and improve the efficiency of electrothermal snow and ice melting systems accordingly.The thermal conductivity of asphalt concrete prepared with different thermally conductive fillers was tested by a transient plane source method,and the related performances were measured.Then the temperature rise rate and surface temperature were studied through field heating tests.Finally,the actual ice melting efficiency of the thermally conductive asphalt concrete was evaluated using an effective electrothermal system.As shown by the experimental results,the composite made of SiC powder and carbon fiber has a high thermal conductivity.When SiC replaces mineral powder,the thermal conductivity of the asphalt mixture increases first and then decreases with the increase of carbon fiber content.In the present study,in particular,the thermal conductivity attained a peak when the carbon fiber content was 0.2%of the aggregate mass.
文摘Effect of the heat treatment, including solution treatment （ST） and aging treatment （AT）, on the prior austenite grain （PAG） size, microstructure and mechanical properties of a precipitation hardening maraging stainless steel was investigated. The results indicate that the relations between PAG size and yield strength （σy） under both ST and AT conditions obey the HalI-Petch relationship. Furthermore, after ST at 1050℃ for 1 h＋cryogenic treated （CT） at -70℃ for 8 h＋AT at 535℃ for 4 h, the tested steel showed its ultimate tensile strength （σb） and σy over 1900 MPa and 1750 MPa, respectively.
文摘The 18%Ni alloy steels provide high strength and toughness, while age-hardenable or PH stainless steels also have good corrosion resistance. This paper focuses on an investigation of the heat treatment, mechanical properties and microstructural development of a new maraging stainless steel. It is reported that the heat treatment process should consist of solution treatment and cryogenic cooling to attain a fully martensitic structure, followed by aging at 813 K. This heat treatment resulted in an ultimate tensile strength of over 1900 MPa combined with good impact toughness. Transmission electron microscopy is used to show that, for the peak-aged condition （813 K/4 h）, nano-sized precipitates, e.g. Ni3Mo and/or R-phase, and a high density of dislocations were uniformly dispersed in the lath martensite matrix. The calculated yield strength, based on a revised Orowan mechanism, is in good agreement with the test data. The steel studied has an ultimate tensile strength over 1900 MPa, excellent fracture toughness, and good resistance against over-aging and relatively good corrosion resistance as well.
基金funded by the Natural Science Foundation of Hubei Province in China,No.02.02.040458
文摘Temporal lobe epilepsy is associated with astrogliosis. Notchl signaling can induce astrogliosis in glioma. However, it remains unknown whether Notchl signaling is involved in the pathogenesis of epilepsy. This study investigated the presence of Notchl, hairy and enhancer of split-l, and glial fibrillary acidic protein in the temporal neocortex and hippocampus of lithium-pilocar- pine-treated rats. The presence of Notchl and hairy and enhancer of split-1 was also explored in brain tissues of patients with intractable temporal lobe epilepsy. Quantitative electroencephalo- gram analysis and behavioral observations were used as auxiliary measures. Results revealed that the presence of Notchl, hairy and enhancer of split-l, and glial fibriUary acidic protein were en- hanced in status epilepticus and vehicle-treated spontaneous recurrent seizures rats, but remain unchanged in the following groups： control, absence of either status epilepticus or spontaneous recurrent seizures, and zileuton-treated spontaneous recurrent seizures. Compared with patient control cases, the presences of Notch1 and hairy and enhancer of split- 1 were upregulated in the temporal neocortex of patients with intractable temporal lobe epilepsy. Therefore, these results suggest that Notchl signaling may play an important role in the onset of temporal lobe epilepsy via astrogliosis. Furthermore, zileuton may be a potential therapeutic strategy for temporal lobe epilepsy by blocking Notchl signaling.
文摘The emission wavelength of InGaN/GaN dot-in-wire LED can be tuned by modifying the nanowire diameter,but it causes mismatched angular distributions between blue,green,and red nanowires because of the excitation of different waveguide modes.Besides,the far-field radiation patterns and light extraction efficiency are typically calculated by center dipoles,which fails to provide accurate results.To address these issues,we first compare the simulation results between central dipole and dipole cloud with experimental data.Next,we calculate and analyze the display metrics for full-color nanowire LEDs by 3D dipole cloud.Finally,we achieve unnoticeable angular color shift within±20°viewing cone for augmented reality(AR)and virtual reality(VR)displays with an improved light extraction efficiency.
基金The authors have received financial support from the National Natural Science Foundation of China(No.52078194)the Key Research and Development Program of Hubei Province(No.2021BGD015)the Knowledge Innovation Project of Wuhan(No.2022010801010259).
文摘The use of carbon-fiber heating cables(CFHC)to achieve effective melting of snow and ice deposited on roads is a method used worldwide.In this study,tensile and compressive tests have been conducted to analyze the mechan-ical properties of the CFHC and assess whether the maximum tensile and compressive strengths can meet the pavement design specifications.In order to study the aging produced by multiple cycles of heating and cooling,in particular,the CFHC was repeatedly heated in a cold chamber with an ambient temperature ranging between-20℃ and+40℃.Moreover,to evaluate how the strength of the pavement is affected by its presence,the CFHC was embedded at different depths and concrete blocks with different curing ages were subjected to relevant com-pression and splitting tensile tests.Numerical simulations based on the ANSYS software have also been performed and compared with the outcomes of the static loading tests.The results show that the CFHC embedded in the concrete does not affect the compressive splitting tensile strengths of the pavement.Overall,the CFHC meets the conditions required for continued use in road ice melting applications.
基金funded by the National Natural Science Foundation of China(Grant Nos.41330527 and 41505068)National Key Program for Global Change Research of China(Grant No.2010CB950500)Fundamental Research Funds of CAMS(Grant No.2015Y004)
文摘One of the key issues in international climate negotiations is the formulation of targets for emissions reduction for all countries based on the principle of ＂common but differentiated responsibilities＂. This formulation depends primarily on the quantitative attribution of the responsibilities of developed and developing countries for historical climate change. Using the Commuity Earth System Model（CESM）, we estimate the responsibilities of developed countries and developing countries for climatic change from 1850 to 2005 using their carbon dioxide, methane and nitrous oxide emissions. The results indicate that developed countries contribute approximately 53%–61%, and developing countries approximately 39%–47%, to the increase in global air temperature, upper oceanic warming, sea-ice reduction in the NH, and permafrost degradation. In addition, the spatial heterogeneity of these changes from 1850 to 2005 is primarily attributed to the emissions of greenhouse gases（GHGs）in developed countries. Although uncertainties remain in the climate model and the external forcings used, GHG emissions in developed countries are the major contributor to the observed climate system changes in the 20 th century.
基金National Natural Science Foundation of China,Grant/Award Number:U1261212。
文摘The spewing of a screw conveyor easily occurs from the earth pressure balance(called EPB)shield in a water-rich sand stratum.This may lead to the collapse of the tunnel face and even serious subsidence of the ground surface.To understand the spewing mechanism of the shield screw conveyor and explore the critical hydraulic condition of soil spewing in a shield–soil chamber,a simplified theoretical model for the spewing of the screw conveyor was developed based on the equation of groundwater flow in the screw conveyor under turbulent state.Thus,coupling Darcy's law with Brinkman's equation,this model was implemented within the COMSOL Multiphysics framework.The underground water flow in the shield screw conveyor was simulated so as to obtain its velocity and flow rate.Numerical simulations show that the water pressure distribution is concentrated in the lower part of the soil chamber after the groundwater enters the soil chamber.When the groundwater enters the screw conveyor,its pressure gradually decreases along the direction of the screw conveyor.When the water flow reaches the stratum–shield interface,the flow velocity changes markedly:first increases and concentrates at the entrance of the lower soil chamber,plummets and stabilizes gradually,and increases again at the exit.The soil chamber and screw conveyor are significantly depressurized.It is also found that the soil permeability coefficient can be reduced to k<2.6×10^(−4)cm/s through appropriate soil improvement,which can effectively prevent the occurrence of spewing disasters.
基金supported by the National Natural Science Foundation of China(no.51175373)the Key Technology and Development Program of the Tianjin Municipal Science and Technology Commission(no.14ZCDZGX00490)
文摘For local radiotherapy, a three-dimensional(3D)conformal localized dose planning protocol has been established in this paper to develop a precise and reasonable dose plan. A precalculated 3D dose map for a single source is obtained using the Monte Carlo method, and the spatial dose maps are combined linearly to acquire the dose distribution. The dose distribution is visualized through the real-time display of the isodose line and isodose surface combined with the reconstructed 3D organ groups. By observing 3D dose coverage to the target volume and surrounding tissues, dose planning could be initiated with greater accuracy and precision to avoid dose dead zones and excessively high-dose levels, thus achieving the 3D conformal dose planning objective. Further research into the impact that blockages have on a needle trajectory can be conducted to optimize the insertion accuracy. A treatment planning system was developed to formulate and implement the 3D local treatment plan before the surgery,during the surgery, and after the surgery. Several experiments pertaining to both single-seed and multiple-seed dose distributions were conducted to verify the accuracy of the single-seed dose calculation module and 3D superposition dose calculation in the treatment planning system.
文摘BACKGROUND： Pseudomonas aeruginosa mannose-sensitive hemagglutinin （PA-MSHA） parenteral injection is used as a broad-spectrum immunomodulator. It remains unclear whether PA-MSHA exhibits inhibitory effects on tumor cell growth. OBJECTIVE： To investigate inhibitory mechanisms of PA-MSHA-induced proliferation in rat C6 glioma cells in vitro. DESIGN, TIME AND SETTING： Comparative observation and in vitro experiments were performed at the Key Laboratory of Natural Medicine, Kunming Medical College, China from July 2008 to April 2009. MATERIALS： Rat C6 glioma cell line （Shanghai Institute of Cell Biology, Chinese Academy of Sciences, China） and PA-MSHA parenteral injection （Beijing Wanteer Bio-Pharmaceutical, China） were used in the present study. METHODS： Rat C6 glioma cells in logarithmic growth phase were harvested in vitro. Adherent monolayer cells were respectively treated with PA-MSHA at final colony-forming units （cfu） of 1 ×10^8 cfu/mL, 2 × 10^8 cfu/mL, 4 × 10^8 cfu/mL, 6 × 10^8 cfu/mL, and 8 ×10^8 cfu/mL following 24 hours of conventional culture. MAIN OUTCOME MEASURES： MTT colorimetric assay was utilized to determine the inhibitory rate of C6 glioma cells following treatment with various concentrations of PA-MSHA at different times. Cell apoptosis was detected by fluorescent microscopy following Hoechst 33258 staining. Flow cytometry was used to measure PA-MSHA effects on C6 cell cycle. RESULTS： Inhibitory rate of C6 glioma cells increased with prolonged time and increased dose. Hoechst 33258 staining revealed obvious morphological changes in apoptotic C6 glioma cells. Flow cytometry revealed hypodiploid peaks, Le., apoptotic peak, and the apoptotic rate in cells during S-phase significantly increased with increased concentrations in the experimental groups. CONCLUSION： With in vitro experiments, PA-MSHA preparations inhibited C6 glioma cell proliferation in a time- and dose-dependent manner. These mechanisms are likely associated with cell apoptosis induction and inhibition of the S phase.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61405080 and 61575086)Jiangsu Collaborative Innovation Centre of Advanced Laser Technology and Emerging Industry,Chinathe Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘The mid-infrared （MIR） luminescent properties of Dy3＋ ions in a new chalcohalide glass host, Ga2S3-Sb2S3-CsI, are investigated; and the suitability of the doped glass for MIR fiber lasers is evaluated. The Dy3＋-doped chalcohalide glasses exhibit good thermal stability and intense MIR emissions around 2.96 μm and 4.41 μm. These emissions show quantum efficiencies （η） as high as ～ 60%, and have relatively large stimulated emission cross sections （σem）. The low phonon energy （～ 307 cm-1） of the host glass accounts for the intense MIR emissions, as well as the high η. These favorable thermal and emission properties make the Dy3＋-doped Ga2S3-Sb2S3-CsI glasses promising materials for MIR fiber amplifiers or lasers.
基金Supported by Shaanxi Agricultural Promotion Program(2012SNJC159NTF-H1)
文摘The concept,research content and direction of biological manufacturing were elaborated in this text. The biological manufacturing progress in China,application situation,development trend and existing problems were analyzed,and the prospect of the development of biological manufacturing was put forward,in order to provide reference and guidance for the manufacture of biological research and industrial development.
文摘Regional climate change impact assessments are becoming increasingly important for developing adaptation strategies in an uncertain future with respect to hydro-climatic extremes. There are a number of Global Climate Models (GCMs) and emission scenarios providing predictions of future changes in climate. As a result, there is a level of uncertainty associated with the decision of which climate models to use for the assessment of climate change impacts. The IPCC has recommended using as many global climate model scenarios as possible;however, this approach may be impractical for regional assessments that are computationally demanding. Methods have been developed to select climate model scenarios, generally consisting of selecting a model with the highest skill (validation), creating an ensemble, or selecting one or more extremes. Validation methods limit analyses to models with higher skill in simulating historical climate, ensemble methods typically take multi model means, median, or percentiles, and extremes methods tend to use scenarios which bound the projected changes in precipitation and temperature. In this paper a quantile regression based validation method is developed and applied to generate a reduced set of GCM-scenarios to analyze daily maximum streamflow uncertainty in the Upper Thames River Basin, Canada, while extremes and percentile ensemble approaches are also used for comparison. Results indicate that the validation method was able to effectively rank and reduce the set of scenarios, while the extremes and percentile ensemble methods were found not to necessarily correlate well with the range of extreme flows for all calendar months and return periods.
文摘Surface with well-defined components and structures possesses unique electronic,magnetic,optical and chemical properties.As a result,surface chemistry research plays a crucial role in various fields such as catalysis,energy,materials,quantum,and microelectronics.Surface science mainly investigates the correspondence between surface property and functionality.Scanning probe microscopy(SPM)techniques are important tools to characterize surface properties because of the capability of atomic-scale imaging,spectroscopy and manipulation at the single-atom level.In this review,we summarize recent advances in surface electronic,magnetic and optical properties characterized mainly by SPM-based methods.We focus on elucidating theπ-magnetism in graphene-based nanostructures,construction of spin qubits on surfaces,topology properties of surface organic structures,STM-based light emission,tip-enhanced Raman spectroscopy and integration of machine learning in SPM studies.
基金supported by the National Natural Science Foundation of China(Nos.22225202,92356309,22132007,21991132,22172002)。
文摘Surface chemistry focuses on the investigation of the adsorption,migration,assembly,activation,reaction,and desorption of atoms and molecules at surfaces.Surface chemistry plays the pivotal roles in both fundamental science and applied technology.This review will summarize the recent progresses on surface assembly,synthesis and catalysis investigated mainly by scanning tunneling microscopy and atomic force microscopy.Surface assemblies of water and small biomolecules,construction of Sierpin′ski triangles and surface chirality are summarized.On-surface synthesis of conjugated carbo-and heterocycles and other kinds of carbon nanostructures are surveyed.Surface model catalysis,including single-atom catalysis and electrochemical catalysis,are discussed at the single-atom level.
基金the National Natural Science Foundation of China(31770501)the Science and Technology Innovation Base Free Research Program of Tibetan Autonomous Region of China(to Zhiyong,Yang).
