In order to simulate changes in the water quality of the Miyun Reservoir dueto continuous descent of surface water level, a 3-D ecological hydrodynamic model was developedthrough coupling the water quality analysis si...In order to simulate changes in the water quality of the Miyun Reservoir dueto continuous descent of surface water level, a 3-D ecological hydrodynamic model was developedthrough coupling the water quality analysis simulation program (WASP) with the environmental fluiddynamics code (EFDC). The model was then calibrated and verified. Four scenarios (S1, S21, S22 andS23) were simulated using the model. Results show that the water quality of the Miyun Reservoirunder conditions of low surface water level is apparently affected by different amounts of inflowand different total phosphorus (TP) loadings. The chlorophyll-a concentration might exceed 10 μg/Lin many areas of the Miyun Reservoir (This limitative value is seen as a critical value ofeutrophication) when large loadings of TP enter due to the amount of inflow increasing. Results ofscenario S23 indicate that control of TP loadings can decrease chlorophyll-a concentrationeffectively, and the water quality of the Miyun Reservoir will improve or retain its status quo.展开更多
A new baccharane-type triterpene, 3-acetoxy-9(11)-baccharene(1),as well as a known compound, a-amyrin(2), has been isolated from the ether extract of the roots of Saussurea lappa C. B. Clarke. The structure of the new...A new baccharane-type triterpene, 3-acetoxy-9(11)-baccharene(1),as well as a known compound, a-amyrin(2), has been isolated from the ether extract of the roots of Saussurea lappa C. B. Clarke. The structure of the new compound was identified by spectrum analysis.展开更多
A new eremophilane sesquiterpenoid, along with two known ones, was isolated from the ethyl acetate soluble fraction of the aerial part of Coleus xanthanthus C. Y. Wu et Y. C. Huang. Their structures were elucidate...A new eremophilane sesquiterpenoid, along with two known ones, was isolated from the ethyl acetate soluble fraction of the aerial part of Coleus xanthanthus C. Y. Wu et Y. C. Huang. Their structures were elucidated as 4,5,11_trimethyl_8,9_seco_1(10),7(11)_eremophiladien_8,12_olid_9_oic acid (1), 2,9_dioxoeuryopsin (2) and 9_oxoeuryopsin (3) by spectral methods. The 1H_NMR and 13 C NMR data of compounds 1, 2 and 3 were unambiguously assigned on the basis of two_dimensional NMR spectroscopy.展开更多
Adsorption process is acknowledged as an effective option for phenolic wastewater treatment. In this work, the activated carbon (AC) samples after thermal modification were prepared by using muffle furnace. The phen...Adsorption process is acknowledged as an effective option for phenolic wastewater treatment. In this work, the activated carbon (AC) samples after thermal modification were prepared by using muffle furnace. The phenol ad- sorption kinetics and equilibrium measurements were carried out under static conditions at temperature ranging from 25 to 55 ~C. The test results show that the thermal modification can enhance phenol adsorption on AC samples. The porous structure and surface chemistry analyses indicate that the decay in pore morphology and decrease of total oxygen-containing functional groups are found for the thermal modified AC samples. Thus, it can be further inferred that the decrease of total oxygen-containing functional groups on the modified AC sam- ples is the main reason for the enhanced phenol adsorption capacity. For both the raw sample and the optimum modified AC sample at 900 ~C, the pseudo-second order kinetics and Langmuir models are found to fit the exper- imental data very well. The maximum phenol adsorption capacity of the optimum modified AC sample can reach 144,93 mg.g ~ which is higher than that of the raw sample, i.e. 119.53 mg.g 1. Adsorption thermodynamics analysis confirms that the phenol adsorption on the optimum modified AC sample is an exothermic process and mainly via physical adsorption.展开更多
The globularization behavior and mechanism of TC17 alloy with basketweave microstructure were investigated, and the models of dynamic and static globularization kinetics were established. The quantitative and metallog...The globularization behavior and mechanism of TC17 alloy with basketweave microstructure were investigated, and the models of dynamic and static globularization kinetics were established. The quantitative and metallographic results show that the globularization of α phase is sensitive to the parameters of deformation and heat treatment. By EBSD analysis, the formation and evolution mechanisms of intra-α boundaries are related to discontinuous dynamic recrystallization and continuous dynamic recrystallization, which can form α grains with high and low misorientations between neighbour grains after the heat treatment, respectively. Based on the globularization behavior and mechanism, two modified JMAK models are developed to predict the dynamic and static globularization kinetics, and the mean absolute relative errors(MARE) of 10.67% and 13.80% indicate the accuracy of the dynamic and static globularization kinetics models. The results of this work can provide guidance for controlling microstructure of titanium alloy.展开更多
The method has been established to calculate the environmental capacity (ECO), surplus environment capacity (SECO) of water with respect to marine petroleum hydrocarbons associated with oil (PHAOs) and the self-purifi...The method has been established to calculate the environmental capacity (ECO), surplus environment capacity (SECO) of water with respect to marine petroleum hydrocarbons associated with oil (PHAOs) and the self-purification capacity (SPCO) of main self-purification process to PHAOs in the Jiaozhou Bay, China, according to the dynamic model for distribution of marine PHAOs among multiphase environments. The variation of concentration of PHAOs in the Jiaozhou Bay is well simulated by the dynamic model. Based on the model, the ECo, SECo of water with respect to PHAOs in the Jiaozhou Bay were calculated during the last 10 years under the first-class and second-class quality standard requirement, according to SPCO of main self-purification process to PHAOs. The results show that about 200 tons of PHAOs could be discharged into the Jiaozhou Bay for maintaining the first class seawater quality standard, and about 600 tons of PHAOs for the second class seawater quality standard later.展开更多
The optical properties of three linear conjugated oligomers (F-P, F-P-F, and P-F-P-F-P), where phenothiazine (P) and fluorene (F) groups arrange alternately, are investigated. With the enhancement of the π-conj...The optical properties of three linear conjugated oligomers (F-P, F-P-F, and P-F-P-F-P), where phenothiazine (P) and fluorene (F) groups arrange alternately, are investigated. With the enhancement of the π-conjugated system, their absorption and emission bands both gradually red shift, and their two-photon properties are also improved. Meanwhile, their fluorescence dynamic traces are analyzed with continuous rate distribution model, exhibiting that their decay rates gradually accelerate and the rate distribution width become narrower. The quantum chemical calculation offers their molecular structures and transition mechanism, showing that the enhancement of π-conjugated system should be responsible for tile improvement of two-photon properties.展开更多
Solar‐driven thermochemical water splitting represents one efficient route to the generation of H2as a clean and renewable fuel.Due to their outstanding catalytic abilities and promising solar fuel production capacit...Solar‐driven thermochemical water splitting represents one efficient route to the generation of H2as a clean and renewable fuel.Due to their outstanding catalytic abilities and promising solar fuel production capacities,perovskite‐type redox catalysts have attracted significant attention in this regard.In the present study,the perovskite series La1‐xCaxMn1‐yAlyO3(x,y=0.2,0.4,0.6,or0.8)was fabricated using a modified Pechini method and comprehensively investigated to determine the applicability of these materials to solar H2production via two‐step thermochemical water splitting.The thermochemical redox behaviors of these perovskites were optimized by doping at either the A(Ca)or B(Al)sites over a broad range of substitution values,from0.2to0.8.Through this doping,a highly efficient perovskite(La0.6Ca0.4Mn0.6Al0.4O3)was developed,which yielded a remarkable H2production rate of429μmol/g during two‐step thermochemical H2O splitting,going between1400and1000°C.Moreover,the performance of the optimized perovskite was found to be eight times higher than that of the benchmark catalyst CeO2under the same experimental conditions.Furthermore,these perovskites also showed impressive catalytic stability during two‐step thermochemical cycling tests.These newly developed La1‐xCaxMn1‐yAlyO3redox catalysts appear to have great potential for future practical applications in thermochemical solar fuel production.展开更多
Fatigue is usually the cause for the cracks identified at bridge elements in service. With an increase in the introduction of corrugated steel web girders in recent highway bridge construction, the understanding of th...Fatigue is usually the cause for the cracks identified at bridge elements in service. With an increase in the introduction of corrugated steel web girders in recent highway bridge construction, the understanding of the fatigue behaviour of welded details in such structures becomes an important issue for the design. The typical welded details were represented as welded joints assembled by longitudinal corrugated plates. All the experiments were performed under fatigue loading using a servo-control testing machine. The test results from the failure mode observation with the aid of infrared thermo-graph technology show that the failure manner of these welded joints is comparable to that of the corrugated steel web beams reported previously. It is indicated from the stiffness degradation analysis that the welded joints with larger corrugation angle have higher stiffness and greater stiffness degradation in the notable stiffness degradation range. It is shown from the test S-N relations based on the free regression and forced regression analyses that there is a good linear dependence between lg(N) and lg(ΔS). It is also demonstrated that the proposed fracture mechanics analytical model is able to give a prediction slightly lower but on the safe side for the mean stresses at 2 million cycles of the test welded joints.展开更多
The objective of our study was to determine the effects of four types of fertilisers enrichments (manure potassic (K), phosphatic (P), phosphatic and potassic (PK) and nitrogenized, phosphated and potassic (NP...The objective of our study was to determine the effects of four types of fertilisers enrichments (manure potassic (K), phosphatic (P), phosphatic and potassic (PK) and nitrogenized, phosphated and potassic (NPK)) on chemical composition and dry matter in cassava (Manihot esculenta) organs (clone 1171) during harvest period. The pots experiment was laid out in randomised complete bloc design with five treatments and four replications. Water, nitrogen, potassium, phosphorus, sodium, total proteins and total lipids contents of the leaves, shoots and tubers were determined. After 9 months growing period, results showed that fertilizer types enriched with K, PK and NPK significantly increased the organic compounds contents of the leaves (P〈0.05). Furthermore, fertilizers with high phosphorus content significantly increased the lipid contents of the leaves (25%). Fertilizers enriched with NPK positively influenced the biomass partitioning in Manihot esculenta. Application of fertilizers enriched with NPK led to higher levels of total proteins in the leaves and tubers (70 mg g DM^-1 and 30 mg g DM^-1 respectively) compared to control (17 mg g DM^-1 and 9 mg g DM^-1 respectively). These results help to demonstrate the value of these fertilizers enrichment to improve the chemical composition and dry matter partitioning of cassava.展开更多
Dynamic alignment of D2 induced by two few-cycle pulses was investigated by solving the time-dependent Schr6dinger equation numerically based on a rigid rotor model. The results show that alignment of D2 can be enhanc...Dynamic alignment of D2 induced by two few-cycle pulses was investigated by solving the time-dependent Schr6dinger equation numerically based on a rigid rotor model. The results show that alignment of D2 can be enhanced by two few-cycle pulses compared with the level achievable by a single few-cycle pulse as long as the time delay between two pulses is chosen properly, and the pulse duration of two lasers plays an important role in the aligning process of D2 molecules.展开更多
The paper presents an investigation of energy and exergy analysis of an existing ORC (organic rankine cycle) unit powered by hot geothermal water. The validated model of this unit was used to examine 25 refrigerants...The paper presents an investigation of energy and exergy analysis of an existing ORC (organic rankine cycle) unit powered by hot geothermal water. The validated model of this unit was used to examine 25 refrigerants belonging to different chemical compositions. The study revealed that R141b and R123 produced the best net power, energy efficiency, and exergy efficiency, whereas R125 was the lowest. Hydrofluorocarbons (except R143a), hydrocarbons, and inorganic reflected attractive energy and exergy efficiencies. All investigated mixtures gained low performance compared with other studied candidates. The R245ca was the best among the hydrofluorocarbons studied refrigerants, and R501 was the best among the mixture refrigerants. Furthermore, within the ORC system, the evaporator was found to have the highest exergy destruction and the refrigerant pump was the lowest.展开更多
Nuclear fuel based on uranium metal alloys is utilized in research and test reactors. For the purpose of the reduction of fuel enrichment, high densities of uranium-235 in this kind of fuel are needed. This can be ach...Nuclear fuel based on uranium metal alloys is utilized in research and test reactors. For the purpose of the reduction of fuel enrichment, high densities of uranium-235 in this kind of fuel are needed. This can be achieved when uranium alloys are used containing elements such as Zr, Mo and Nb. The construction of fuel element with high-uranium density requires materials with low cross sections for neutron absorption, stability under irradiation and absence of the chemical interactions between the fuel and cladding elements. In case of U-Zr-Nb alloys, Zry (zircaloy) cladding is a better option due to the fact that they have a higher chemical compatibility when compared with the use of aluminum alloys. This study aims to develop plate type nuclear fuel using the U-2.5Zr-7.5Nb alloy dispersed in Zry. Powders of this uranium based alloy and Zry were obtained by hydriding-dehydriding process. These powders were homogenized, compacted in pellet that was sandwiched in plates and frame of Zry. This assembly was hot rolled forming the dispersion fuel miniplate.展开更多
Phosphorus fractionation and sorption, both separately and jointly, were studied in two cultivated Inceptisols in Northern Greece. Hedley's extraction was used to separate soil phosphorus (P) into inorganic Pi (ge...Phosphorus fractionation and sorption, both separately and jointly, were studied in two cultivated Inceptisols in Northern Greece. Hedley's extraction was used to separate soil phosphorus (P) into inorganic Pi (geochemical) and organic Po (biological) fractions. Direct extractable P by Olsen (Olsen-P), by Mehlich llI (M3-P) and by ammonium oxalate (Pox) was also determined. Phosphorus sorption was carried out with 1:10 soil/solution ratio and sorption parameters were derived from the Langmuir model to the experimental data. Most of the total P occurred in inorganic P forms (74% of Pt), while organic P comprised only 26% of the Pt. Among the various inorganic P forms relatively large amount of residual P (111 mg kg^-1) was observed, while occluded P in calcium phosphate minerals (d.HCI-Pi) and in Fe, Al-oxides (c.HCI-Pi) existed in equal amounts (83.1 and 83.7 mg kg^-1 respectively). The phosphorus sorption parameters showed positive relationships with clay content, cation exchange capacity and the sum of exchangeable calcium plus magnesium. Overall, this study indicated that Ca and Mg compounds strongly influence the P chemistry in moderately weathered soils, with relatively high concentration of primary P minerals.展开更多
River estuarine environment plays a key role in the cycling of biological and chemical parameters and a significant region for the transaction of freshwater and seawater. In the present study, a first attempt has been...River estuarine environment plays a key role in the cycling of biological and chemical parameters and a significant region for the transaction of freshwater and seawater. In the present study, a first attempt has been made towards the development of a coupled three-dimensional hydrodynamic circulation model with four compartment (nitrate, phytoplankton, zooplankton and detritus) biogeochemical model in the Hooghly estuary (21 °36′-22° 16′1 and 87°42'-88°15′E) to simulate the varying effect of plankton biomass with the heavy input of anthropogenic litter from industrial effluents of Haldia port which is effecting the chemical and biological processes that control the plankton dynamics in the estuary. In-situ observational data for physico-chemical and biological parameters are collected from Calcutta University during 2010 are assimilated using multiscale OA (objective analysis) for different seasons and incorporated in ROMS (Regional Ocean Modeling System) to develop a high resolution (0.5 km x 0.5 kin) biogeochemical model. Recent analysis on physico-chemical parameters of the estuary is done as it is one of the largest estuaries in India and is the habitat for vast biodiversity. Influence of high nitrate (above 34 μg/L) and phosphate (5.22 μg/L) is predominant whereas DO (dissolved oxygen) is low (4.07 mg/L) in the Haldi River mouth which is sliding the productivity (less than 1 mg/L) and also affects water quality.展开更多
The study is focused on modeling of separation process and optimization.An adsorption separation process is simulated.The surfactin production process by Bacillus subtilis ATCC 21332 followed by surfactin adsorption i...The study is focused on modeling of separation process and optimization.An adsorption separation process is simulated.The surfactin production process by Bacillus subtilis ATCC 21332 followed by surfactin adsorption in a fixed-bed column packed with commercial active carbon is studied in laboratory.The adsorption column achieves high surfactin recovery(94%)by up-flow methanol elution at 25°C.The adsorption column is simulated with a complex one-dimensional plug flow dispersion model coupled with nonlinear adsorption equilibrium,based on the assumption that the adsorption of surfactin is monomolecular layer and no micelle is formed.The molecular diffusion coefficient of surfactin in water solution with electric neutrality is estimated to be 0.428×10 -5 cm 2 ·s -1 by molecular dynamics simulation.The model developed can describe the complex interplay of adsorption kinetics,fluid dynamics,and mass-transfer phenomena based on the assumption of no radial temperature and concentration gradients,and is of adequate precision.The work involved in this paper is valuable for the optimization of the production process of surfactin.展开更多
Recent development in the use of the environmental radionuclide caesium-137 for documenting rates and soil redistribution on the cultivated or uncultivated land and estimating rates of sediment deposition on represent...Recent development in the use of the environmental radionuclide caesium-137 for documenting rates and soil redistribution on the cultivated or uncultivated land and estimating rates of sediment deposition on represents an important advance that overcomes many of the limitations of the conventional techniques commonly applied in such investigations. A study on soil redistribution (including soil erosion and deposition) was carried out in the Dian Lake catchment, Yunnan Province, using ^137Cs and selected chemical properties. The average soil erosion rate was 1,280.2 t km^2 yr^-1. Soil erosion rate occurring on different parts of the slope was significantly different on different parts of the slope, increasing.from the top. the bottom to the middle slope. The average soil erosion rate is also different with the land use type and that of the cultivated land (1, 672. 8 t km^-2 yr^-1) is higher than oJ the uncultivated land (1.161.2t km^-2 yr^-1 ). The result shows that landform, slope gradient and land use type are key factors that influence the size of soil erosion. In addition, we also find the SOC and TN contents and amount of the soil erosion to be correlated in the soil. With the soil erosion occurring, there are land degradation and the local eco-environmental problems, such as water eutrophication in Dian Lake.展开更多
文摘In order to simulate changes in the water quality of the Miyun Reservoir dueto continuous descent of surface water level, a 3-D ecological hydrodynamic model was developedthrough coupling the water quality analysis simulation program (WASP) with the environmental fluiddynamics code (EFDC). The model was then calibrated and verified. Four scenarios (S1, S21, S22 andS23) were simulated using the model. Results show that the water quality of the Miyun Reservoirunder conditions of low surface water level is apparently affected by different amounts of inflowand different total phosphorus (TP) loadings. The chlorophyll-a concentration might exceed 10 μg/Lin many areas of the Miyun Reservoir (This limitative value is seen as a critical value ofeutrophication) when large loadings of TP enter due to the amount of inflow increasing. Results ofscenario S23 indicate that control of TP loadings can decrease chlorophyll-a concentrationeffectively, and the water quality of the Miyun Reservoir will improve or retain its status quo.
基金This work was supported by the Kunming Institute of Botany,Chinese Academy of Sciences.
文摘A new baccharane-type triterpene, 3-acetoxy-9(11)-baccharene(1),as well as a known compound, a-amyrin(2), has been isolated from the ether extract of the roots of Saussurea lappa C. B. Clarke. The structure of the new compound was identified by spectrum analysis.
文摘A new eremophilane sesquiterpenoid, along with two known ones, was isolated from the ethyl acetate soluble fraction of the aerial part of Coleus xanthanthus C. Y. Wu et Y. C. Huang. Their structures were elucidated as 4,5,11_trimethyl_8,9_seco_1(10),7(11)_eremophiladien_8,12_olid_9_oic acid (1), 2,9_dioxoeuryopsin (2) and 9_oxoeuryopsin (3) by spectral methods. The 1H_NMR and 13 C NMR data of compounds 1, 2 and 3 were unambiguously assigned on the basis of two_dimensional NMR spectroscopy.
基金Supported by the National Natural Science Foundation of China(41302132)Training Programmes of Innovation and Entrepreneurship for Undergraduates of Yunnan Province(Grant No.201510674042)the Introduced Talents Foundation of Kunming University of Science and Technology(KKSY201205160)
文摘Adsorption process is acknowledged as an effective option for phenolic wastewater treatment. In this work, the activated carbon (AC) samples after thermal modification were prepared by using muffle furnace. The phenol ad- sorption kinetics and equilibrium measurements were carried out under static conditions at temperature ranging from 25 to 55 ~C. The test results show that the thermal modification can enhance phenol adsorption on AC samples. The porous structure and surface chemistry analyses indicate that the decay in pore morphology and decrease of total oxygen-containing functional groups are found for the thermal modified AC samples. Thus, it can be further inferred that the decrease of total oxygen-containing functional groups on the modified AC sam- ples is the main reason for the enhanced phenol adsorption capacity. For both the raw sample and the optimum modified AC sample at 900 ~C, the pseudo-second order kinetics and Langmuir models are found to fit the exper- imental data very well. The maximum phenol adsorption capacity of the optimum modified AC sample can reach 144,93 mg.g ~ which is higher than that of the raw sample, i.e. 119.53 mg.g 1. Adsorption thermodynamics analysis confirms that the phenol adsorption on the optimum modified AC sample is an exothermic process and mainly via physical adsorption.
基金the support from the Science Fund for Distinguished Young Scholars from Shaanxi Province, China (No. 2020JC-17)the National Natural Science Foundation of China (No. 51705425)+1 种基金the Research Fund of the State Key Laboratory of Solidification Processing (NWPU), China (No. 2019-QZ-04)the Fundamental Research Funds for the Central Universities, China (No. 3102019PY007)。
文摘The globularization behavior and mechanism of TC17 alloy with basketweave microstructure were investigated, and the models of dynamic and static globularization kinetics were established. The quantitative and metallographic results show that the globularization of α phase is sensitive to the parameters of deformation and heat treatment. By EBSD analysis, the formation and evolution mechanisms of intra-α boundaries are related to discontinuous dynamic recrystallization and continuous dynamic recrystallization, which can form α grains with high and low misorientations between neighbour grains after the heat treatment, respectively. Based on the globularization behavior and mechanism, two modified JMAK models are developed to predict the dynamic and static globularization kinetics, and the mean absolute relative errors(MARE) of 10.67% and 13.80% indicate the accuracy of the dynamic and static globularization kinetics models. The results of this work can provide guidance for controlling microstructure of titanium alloy.
基金Supported bythe National Natural Science Foundation of China projects ( NSFC-40136020 NSFC-40376033)the National +1 种基金Basic Research Priorities Programme (2001CB409703)the Key Project of Chinese Ministry of Education (No.01110)Shandong Nature Science
文摘The method has been established to calculate the environmental capacity (ECO), surplus environment capacity (SECO) of water with respect to marine petroleum hydrocarbons associated with oil (PHAOs) and the self-purification capacity (SPCO) of main self-purification process to PHAOs in the Jiaozhou Bay, China, according to the dynamic model for distribution of marine PHAOs among multiphase environments. The variation of concentration of PHAOs in the Jiaozhou Bay is well simulated by the dynamic model. Based on the model, the ECo, SECo of water with respect to PHAOs in the Jiaozhou Bay were calculated during the last 10 years under the first-class and second-class quality standard requirement, according to SPCO of main self-purification process to PHAOs. The results show that about 200 tons of PHAOs could be discharged into the Jiaozhou Bay for maintaining the first class seawater quality standard, and about 600 tons of PHAOs for the second class seawater quality standard later.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China. (No.21103161. No.11274142, No.11304058, No.11274034. and No.11004080) and the China Postdoctoral Science Foundation (No.2011MS00927 and No.2013T60319).
文摘The optical properties of three linear conjugated oligomers (F-P, F-P-F, and P-F-P-F-P), where phenothiazine (P) and fluorene (F) groups arrange alternately, are investigated. With the enhancement of the π-conjugated system, their absorption and emission bands both gradually red shift, and their two-photon properties are also improved. Meanwhile, their fluorescence dynamic traces are analyzed with continuous rate distribution model, exhibiting that their decay rates gradually accelerate and the rate distribution width become narrower. The quantum chemical calculation offers their molecular structures and transition mechanism, showing that the enhancement of π-conjugated system should be responsible for tile improvement of two-photon properties.
基金supported by the Australian Research Council(FT120100913)the National Natural Science Foundation of China(51372248,51432009)~~
文摘Solar‐driven thermochemical water splitting represents one efficient route to the generation of H2as a clean and renewable fuel.Due to their outstanding catalytic abilities and promising solar fuel production capacities,perovskite‐type redox catalysts have attracted significant attention in this regard.In the present study,the perovskite series La1‐xCaxMn1‐yAlyO3(x,y=0.2,0.4,0.6,or0.8)was fabricated using a modified Pechini method and comprehensively investigated to determine the applicability of these materials to solar H2production via two‐step thermochemical water splitting.The thermochemical redox behaviors of these perovskites were optimized by doping at either the A(Ca)or B(Al)sites over a broad range of substitution values,from0.2to0.8.Through this doping,a highly efficient perovskite(La0.6Ca0.4Mn0.6Al0.4O3)was developed,which yielded a remarkable H2production rate of429μmol/g during two‐step thermochemical H2O splitting,going between1400and1000°C.Moreover,the performance of the optimized perovskite was found to be eight times higher than that of the benchmark catalyst CeO2under the same experimental conditions.Furthermore,these perovskites also showed impressive catalytic stability during two‐step thermochemical cycling tests.These newly developed La1‐xCaxMn1‐yAlyO3redox catalysts appear to have great potential for future practical applications in thermochemical solar fuel production.
基金Projects(51308363,11327801)supported by the National Natural Science Foundation of ChinaProject(2013-1792-9-4)supported by the Scientific Research Foundation for the Returned Overseas Chinese ScholarsProject(YJ201307)supported by the Start-up Research Fund for Introduced Talents of Sichuan University,China
文摘Fatigue is usually the cause for the cracks identified at bridge elements in service. With an increase in the introduction of corrugated steel web girders in recent highway bridge construction, the understanding of the fatigue behaviour of welded details in such structures becomes an important issue for the design. The typical welded details were represented as welded joints assembled by longitudinal corrugated plates. All the experiments were performed under fatigue loading using a servo-control testing machine. The test results from the failure mode observation with the aid of infrared thermo-graph technology show that the failure manner of these welded joints is comparable to that of the corrugated steel web beams reported previously. It is indicated from the stiffness degradation analysis that the welded joints with larger corrugation angle have higher stiffness and greater stiffness degradation in the notable stiffness degradation range. It is shown from the test S-N relations based on the free regression and forced regression analyses that there is a good linear dependence between lg(N) and lg(ΔS). It is also demonstrated that the proposed fracture mechanics analytical model is able to give a prediction slightly lower but on the safe side for the mean stresses at 2 million cycles of the test welded joints.
文摘The objective of our study was to determine the effects of four types of fertilisers enrichments (manure potassic (K), phosphatic (P), phosphatic and potassic (PK) and nitrogenized, phosphated and potassic (NPK)) on chemical composition and dry matter in cassava (Manihot esculenta) organs (clone 1171) during harvest period. The pots experiment was laid out in randomised complete bloc design with five treatments and four replications. Water, nitrogen, potassium, phosphorus, sodium, total proteins and total lipids contents of the leaves, shoots and tubers were determined. After 9 months growing period, results showed that fertilizer types enriched with K, PK and NPK significantly increased the organic compounds contents of the leaves (P〈0.05). Furthermore, fertilizers with high phosphorus content significantly increased the lipid contents of the leaves (25%). Fertilizers enriched with NPK positively influenced the biomass partitioning in Manihot esculenta. Application of fertilizers enriched with NPK led to higher levels of total proteins in the leaves and tubers (70 mg g DM^-1 and 30 mg g DM^-1 respectively) compared to control (17 mg g DM^-1 and 9 mg g DM^-1 respectively). These results help to demonstrate the value of these fertilizers enrichment to improve the chemical composition and dry matter partitioning of cassava.
文摘Dynamic alignment of D2 induced by two few-cycle pulses was investigated by solving the time-dependent Schr6dinger equation numerically based on a rigid rotor model. The results show that alignment of D2 can be enhanced by two few-cycle pulses compared with the level achievable by a single few-cycle pulse as long as the time delay between two pulses is chosen properly, and the pulse duration of two lasers plays an important role in the aligning process of D2 molecules.
文摘The paper presents an investigation of energy and exergy analysis of an existing ORC (organic rankine cycle) unit powered by hot geothermal water. The validated model of this unit was used to examine 25 refrigerants belonging to different chemical compositions. The study revealed that R141b and R123 produced the best net power, energy efficiency, and exergy efficiency, whereas R125 was the lowest. Hydrofluorocarbons (except R143a), hydrocarbons, and inorganic reflected attractive energy and exergy efficiencies. All investigated mixtures gained low performance compared with other studied candidates. The R245ca was the best among the hydrofluorocarbons studied refrigerants, and R501 was the best among the mixture refrigerants. Furthermore, within the ORC system, the evaporator was found to have the highest exergy destruction and the refrigerant pump was the lowest.
文摘Nuclear fuel based on uranium metal alloys is utilized in research and test reactors. For the purpose of the reduction of fuel enrichment, high densities of uranium-235 in this kind of fuel are needed. This can be achieved when uranium alloys are used containing elements such as Zr, Mo and Nb. The construction of fuel element with high-uranium density requires materials with low cross sections for neutron absorption, stability under irradiation and absence of the chemical interactions between the fuel and cladding elements. In case of U-Zr-Nb alloys, Zry (zircaloy) cladding is a better option due to the fact that they have a higher chemical compatibility when compared with the use of aluminum alloys. This study aims to develop plate type nuclear fuel using the U-2.5Zr-7.5Nb alloy dispersed in Zry. Powders of this uranium based alloy and Zry were obtained by hydriding-dehydriding process. These powders were homogenized, compacted in pellet that was sandwiched in plates and frame of Zry. This assembly was hot rolled forming the dispersion fuel miniplate.
文摘Phosphorus fractionation and sorption, both separately and jointly, were studied in two cultivated Inceptisols in Northern Greece. Hedley's extraction was used to separate soil phosphorus (P) into inorganic Pi (geochemical) and organic Po (biological) fractions. Direct extractable P by Olsen (Olsen-P), by Mehlich llI (M3-P) and by ammonium oxalate (Pox) was also determined. Phosphorus sorption was carried out with 1:10 soil/solution ratio and sorption parameters were derived from the Langmuir model to the experimental data. Most of the total P occurred in inorganic P forms (74% of Pt), while organic P comprised only 26% of the Pt. Among the various inorganic P forms relatively large amount of residual P (111 mg kg^-1) was observed, while occluded P in calcium phosphate minerals (d.HCI-Pi) and in Fe, Al-oxides (c.HCI-Pi) existed in equal amounts (83.1 and 83.7 mg kg^-1 respectively). The phosphorus sorption parameters showed positive relationships with clay content, cation exchange capacity and the sum of exchangeable calcium plus magnesium. Overall, this study indicated that Ca and Mg compounds strongly influence the P chemistry in moderately weathered soils, with relatively high concentration of primary P minerals.
文摘River estuarine environment plays a key role in the cycling of biological and chemical parameters and a significant region for the transaction of freshwater and seawater. In the present study, a first attempt has been made towards the development of a coupled three-dimensional hydrodynamic circulation model with four compartment (nitrate, phytoplankton, zooplankton and detritus) biogeochemical model in the Hooghly estuary (21 °36′-22° 16′1 and 87°42'-88°15′E) to simulate the varying effect of plankton biomass with the heavy input of anthropogenic litter from industrial effluents of Haldia port which is effecting the chemical and biological processes that control the plankton dynamics in the estuary. In-situ observational data for physico-chemical and biological parameters are collected from Calcutta University during 2010 are assimilated using multiscale OA (objective analysis) for different seasons and incorporated in ROMS (Regional Ocean Modeling System) to develop a high resolution (0.5 km x 0.5 kin) biogeochemical model. Recent analysis on physico-chemical parameters of the estuary is done as it is one of the largest estuaries in India and is the habitat for vast biodiversity. Influence of high nitrate (above 34 μg/L) and phosphate (5.22 μg/L) is predominant whereas DO (dissolved oxygen) is low (4.07 mg/L) in the Haldi River mouth which is sliding the productivity (less than 1 mg/L) and also affects water quality.
文摘The study is focused on modeling of separation process and optimization.An adsorption separation process is simulated.The surfactin production process by Bacillus subtilis ATCC 21332 followed by surfactin adsorption in a fixed-bed column packed with commercial active carbon is studied in laboratory.The adsorption column achieves high surfactin recovery(94%)by up-flow methanol elution at 25°C.The adsorption column is simulated with a complex one-dimensional plug flow dispersion model coupled with nonlinear adsorption equilibrium,based on the assumption that the adsorption of surfactin is monomolecular layer and no micelle is formed.The molecular diffusion coefficient of surfactin in water solution with electric neutrality is estimated to be 0.428×10 -5 cm 2 ·s -1 by molecular dynamics simulation.The model developed can describe the complex interplay of adsorption kinetics,fluid dynamics,and mass-transfer phenomena based on the assumption of no radial temperature and concentration gradients,and is of adequate precision.The work involved in this paper is valuable for the optimization of the production process of surfactin.
基金sponsored by the fund on soil ero-sion and silt source of Dian Lake catchment (Grant No. 40473052).
文摘Recent development in the use of the environmental radionuclide caesium-137 for documenting rates and soil redistribution on the cultivated or uncultivated land and estimating rates of sediment deposition on represents an important advance that overcomes many of the limitations of the conventional techniques commonly applied in such investigations. A study on soil redistribution (including soil erosion and deposition) was carried out in the Dian Lake catchment, Yunnan Province, using ^137Cs and selected chemical properties. The average soil erosion rate was 1,280.2 t km^2 yr^-1. Soil erosion rate occurring on different parts of the slope was significantly different on different parts of the slope, increasing.from the top. the bottom to the middle slope. The average soil erosion rate is also different with the land use type and that of the cultivated land (1, 672. 8 t km^-2 yr^-1) is higher than oJ the uncultivated land (1.161.2t km^-2 yr^-1 ). The result shows that landform, slope gradient and land use type are key factors that influence the size of soil erosion. In addition, we also find the SOC and TN contents and amount of the soil erosion to be correlated in the soil. With the soil erosion occurring, there are land degradation and the local eco-environmental problems, such as water eutrophication in Dian Lake.