In order to evaluate interstitial strengthening effect on the properties of high entropy alloy(HEA),a nitrogen-doped Cr Mn Fe VTi6 HEA was fabricated by mechanical alloying(MA)and spark plasma sintering(SPS).XRD,SEM,T...In order to evaluate interstitial strengthening effect on the properties of high entropy alloy(HEA),a nitrogen-doped Cr Mn Fe VTi6 HEA was fabricated by mechanical alloying(MA)and spark plasma sintering(SPS).XRD,SEM,TEM and FIB were used to characterize the phase composition and microstructure of this material.The sintered bulk HEA exhibits a microstructure comprising TiNx,BCC,Laves and B2 phases.The HEA exhibits high yield strength(>2729 MPa)and hardness in lower temperature range of<380℃.Quantitative calculations of the contributions from each strengthening mechanism in the BCC phase indicate that the interstitial strengthening by nitrogen is the dominant mechanism.Nitrogen additions in the BCC phase can produce a yield strength increase of-634 MPa/at.%,which is much higher than the strengthening effects of carbon or boron additions in other alloys.This demonstrates that adding nitrogen is a viable approach for enhancing the strength of HEAs.展开更多
Pot and adsorpt ion- exchange experiments were carried out by collecting the soil samples from the surfacelayer (0~15 cm) of red soil at the Ecological Experiment Station of Red Soil, the Chinese Academy of Sciences,i...Pot and adsorpt ion- exchange experiments were carried out by collecting the soil samples from the surfacelayer (0~15 cm) of red soil at the Ecological Experiment Station of Red Soil, the Chinese Academy of Sciences,in Jiangxi Province of China. When concentration of the exogenous La3+ exceeded 400 mg kg-1, therewas less non-exchangeable La3+ than exchangeable La3+ in the soil. Cation exchange capacity of the soilchanged slightly with increasing concentration of the exogenous La3+ in both experiments. However, in theadsorption-exchange experiment, when concentration of the exogenous La3+ was higher than 3Oo mg kg-1 ,exchangeable basic cations decreased significantly, while exchangeable hydrogen and exchangeable aluminumincreased significantly compared with the control treatments. The amounts of base cations (Ca2+ ) Mg2+, K+and Na+) exchanged by La3+ in the supernatant solution increased with the concentration of the exogenousLa3+, especially when concentration of the exogenous La3+ was higher than 50 mg kg-1.展开更多
The effects of low frequency electromagnetic (LFEC) field and ultrasonic (US) field on the microstructures, macrosegregation of alloying elements and the mechanical properties of DC cast AZ80 alloy were studied. The r...The effects of low frequency electromagnetic (LFEC) field and ultrasonic (US) field on the microstructures, macrosegregation of alloying elements and the mechanical properties of DC cast AZ80 alloy were studied. The results show that both LFEC and US fields can refine the grains of the billets, which results in the increase in mechanical properties and uniformity of alloying element distribution. The effective refinement takes place on the edge of ingots when LFEC field is applied, while in the center of billets when field US is adopted. Combined the characteristics of LFEC and US fields, a new process for direct-chilling (DC) casting of Mg-electromagnetic-ultrasonic (ECUS) casting is developed, by which the grains are refined significantly and are more uniform in the whole ingots, and the mechanical properties of the ingots are improved.展开更多
In Desire Under the Elms, Eugene O＇Neill not only adopts some elements from Greek tragedies, but brings more different ideas for readers, such as supernaturalism, and the degeneration of the tragic heroes or the peas...In Desire Under the Elms, Eugene O＇Neill not only adopts some elements from Greek tragedies, but brings more different ideas for readers, such as supernaturalism, and the degeneration of the tragic heroes or the peasant like language and sets more comic elements. Under his powerful pen, a marvelous drama is displayed before the audience, which combines the traditional elements and modem creations perfectly. This paper aims to explore the important elements in the play and compare those with what are used in Desire Under the Elms so as to draw the conclusion that Eugene O＇Neill not only uses the traditional written skills but also improves the development and inheritance of Greek tragedies.展开更多
We tested for fourteen trace elements in samples collected from the Ordovician strata in Datun coal field. The vertical concentration variation of these trace dements is reported. The relationship of the variation to ...We tested for fourteen trace elements in samples collected from the Ordovician strata in Datun coal field. The vertical concentration variation of these trace dements is reported. The relationship of the variation to the water-bearing capacity of the Ordovician strata is discussed. The minimum concentration of eleven （of 14 total） trace elements appears in the lower Majiagou formation. The maximum concentrations mainly appear in the Badou and Jiawang formations： eight maxima are located in Badou and four more are in Jiawang. The study of karst development and the water-bearing capacity of Ordovician strata shows that karst is well developed in the Majiagou formation and there is a consequent high water-bearing capacity in this formation： Badou and Jiawang formations are contrary to this situation. The results illustrate that the minimum concentrations of most trace elements within certain Ordovician formations can be taken as strong evidence for the existence of a well developed karst and a high water-bearing capacity.展开更多
A new magnesium alloy plate added elements Zn, Sn and In was manufactured by twin-roll continuous casting method to improve the precipitation of AZ91 alloy. The effects of elements addition and casting method on micro...A new magnesium alloy plate added elements Zn, Sn and In was manufactured by twin-roll continuous casting method to improve the precipitation of AZ91 alloy. The effects of elements addition and casting method on microstructure and mechanical properties of the Mg-Zn-In-Sn alloys were investigated by optical microscopy (OM), transmission electron microscopy (TEM), electron probe micro-analysis (EPMA), X-ray diffractometry (XRD) and energy dispersion spectrograph (EDS). The results show that the Mg-Zn-In-Sn alloy has higher tensile strength and better corrosion protection than the AZ91 alloy. The outstanding precipitation strengthening effect of the alloy is attributed to the small grain size and the hard precipitates between the grain boundaries.展开更多
The purpose of this study was to construct bases for exploring the process of skill acquisition from the viewpoint of eye-hand coordination. The information obtained from eye-gaze is closely related to physical moveme...The purpose of this study was to construct bases for exploring the process of skill acquisition from the viewpoint of eye-hand coordination. The information obtained from eye-gaze is closely related to physical movements in any activity. It is important to establish a method to measure eye-hand coordination for extracting skilled elements and understanding the skill acquisition process. Using a system which consists of an eye mark recorder and a three-dimensional location measurement device, a method for measuring eye-hand coordination was proposed on the basis of the simultaneous measurement of eye-gaze and brush tip locations. After describing the measurement algorithm, the eye-hand coordination during calligraphy was exemplified. More concretely, using such a system, an attempt was made to show that the relationship between the line of eye-gaze and the brush tip stroke was different between a novice and an expert. In such a way, we suggested that the proposed method is promising for exploring the process of skill acquisition.展开更多
Oxidative stress therapy targeted on ox plays idativ critical role in the pathogenesis of chronic obstructive e stress is of great importance for COPD. However, since pu the lmonary disease （COPD）, so current used a...Oxidative stress therapy targeted on ox plays idativ critical role in the pathogenesis of chronic obstructive e stress is of great importance for COPD. However, since pu the lmonary disease （COPD）, so current used antioxidants are not satisfying, scientists have to find more effective antioxidants for COPD. Hydrogen, the most abundant chemical element in the universe, was recently discovered as a novel therapeutic medical gas, and has shown great antioxidant potential in a series of recent published researches for its feature of selectively reducing toxic reactive oxygen species. Based on these findings, we hypothesize that hydrogen gas therapy might be a novel, effective, safe, and economic treatment for COPD patients in one day展开更多
The effects of Sn and Ga additions on the glass forming ability （GFA） of （A186LasNi9）100_xSnx（x=0, 0.2, 0.3, 0.5, 0.7, 1 and 2 at.%） and （Al86LasNi9）100_xGax（x=0, 0.2, 0.5, 1 and 1.5 at.%） alloys were system...The effects of Sn and Ga additions on the glass forming ability （GFA） of （A186LasNi9）100_xSnx（x=0, 0.2, 0.3, 0.5, 0.7, 1 and 2 at.%） and （Al86LasNi9）100_xGax（x=0, 0.2, 0.5, 1 and 1.5 at.%） alloys were systematically investigated. Unlike common microal- loying methods, both Sn and Ga have a positive heat of mixing with the main component of A1. Our analysis confirmed that proper Sn addition can suppress the strong formation of a-A1 and enhance the GFA due to the positive heat of mixing between Sn and AI and the large difference in their atomic sizes. While the addition of Ga to the base alloy acted as the nucleation cites for ct-Al and accelerated precipitation of the ct-A1 phase, thus deteriorating the GFA.展开更多
Using the concept of base forces as state variables,a new finite element method-the base force element method (BFEM) on complementary energy principle for linear elasticity problems is presented.Firstly,an explicit ex...Using the concept of base forces as state variables,a new finite element method-the base force element method (BFEM) on complementary energy principle for linear elasticity problems is presented.Firstly,an explicit expression of compliance matrix for an element is derived through base forces by dyadic vectors.Then,the explicit control equations of finite element method of complementary energy principle are derived using Lagrange multiplier method.Thereafter,the base forces element procedure for linear elasticity is developed.Finally,several examples are analyzed to illustrate the reliability and accuracy of the formulation and the procedure.展开更多
A type of hollow cylinder joints connected with H-shaped beams is proposed for spatial structures. Based on von Mises yield criterion and perfect elasto-plasticity model, a series of finite element models of the joint...A type of hollow cylinder joints connected with H-shaped beams is proposed for spatial structures. Based on von Mises yield criterion and perfect elasto-plasticity model, a series of finite element models of the joints is established, in which the effect of geometric nonlinearity is taken into account. Then mechanical behavior and load-carrying capacity of the joints were investigated, which were subjected to axial load, in- and out-plane bending moments, and their combinations. The results show that the ultimate loads of the joints are determined by the maximum displacement. Furthermore, the case of one joint connected with multiple beams was discussed. Experiments on a set of typical full-scale joints were conducted to understand the structural behavior and the failure mechanism of joint, and also to validate the finite element models. Finally, the practical calculation method was established through finite elements analysis (FEA) results and numerical fitting. The results show that the joints are more ductile and materially economical than welded hollow spherical joints, and the practical calculation method can provide a reference for direct design and the revision of relevant design codes.展开更多
By means of first-principles calculations,we have investigated the effects of rare earth elements (REEs) on the structures and mechanical properties of magnesium.The lattice parameters,elastic constants,bulk moduli,sh...By means of first-principles calculations,we have investigated the effects of rare earth elements (REEs) on the structures and mechanical properties of magnesium.The lattice parameters,elastic constants,bulk moduli,shear moduli,Young's moduli and anisotropic parameter of these solid solutions have been calculated and analyzed.The nearest-neighbor distance between Mg and the REEs is also analyzed to explore the correlation with the bulk moduli.The results show that the 4f-electrons and atomic radii play an important role in the strengthening process.The anomalies of the lattice parameters and mechanical properties at Eu and Yb are due to the half-filled and full-filled 4f-electron orbital states.Finally,the increase of directional bonding character near the alloying elements may account for the anisotropy and brittleness of these magnesium alloys.展开更多
文摘In order to evaluate interstitial strengthening effect on the properties of high entropy alloy(HEA),a nitrogen-doped Cr Mn Fe VTi6 HEA was fabricated by mechanical alloying(MA)and spark plasma sintering(SPS).XRD,SEM,TEM and FIB were used to characterize the phase composition and microstructure of this material.The sintered bulk HEA exhibits a microstructure comprising TiNx,BCC,Laves and B2 phases.The HEA exhibits high yield strength(>2729 MPa)and hardness in lower temperature range of<380℃.Quantitative calculations of the contributions from each strengthening mechanism in the BCC phase indicate that the interstitial strengthening by nitrogen is the dominant mechanism.Nitrogen additions in the BCC phase can produce a yield strength increase of-634 MPa/at.%,which is much higher than the strengthening effects of carbon or boron additions in other alloys.This demonstrates that adding nitrogen is a viable approach for enhancing the strength of HEAs.
文摘Pot and adsorpt ion- exchange experiments were carried out by collecting the soil samples from the surfacelayer (0~15 cm) of red soil at the Ecological Experiment Station of Red Soil, the Chinese Academy of Sciences,in Jiangxi Province of China. When concentration of the exogenous La3+ exceeded 400 mg kg-1, therewas less non-exchangeable La3+ than exchangeable La3+ in the soil. Cation exchange capacity of the soilchanged slightly with increasing concentration of the exogenous La3+ in both experiments. However, in theadsorption-exchange experiment, when concentration of the exogenous La3+ was higher than 3Oo mg kg-1 ,exchangeable basic cations decreased significantly, while exchangeable hydrogen and exchangeable aluminumincreased significantly compared with the control treatments. The amounts of base cations (Ca2+ ) Mg2+, K+and Na+) exchanged by La3+ in the supernatant solution increased with the concentration of the exogenousLa3+, especially when concentration of the exogenous La3+ was higher than 50 mg kg-1.
基金Projects(2007CB613701, 2007CB613702) supported by the National Basic Research Program of ChinaProjects(50974037, 50904018) supported by the National Natural Science Foundation of China+1 种基金Project(NCET-08-0098) supported by New Century Excellent Talents in Chinese UniversityProject(N90209002) supported by the Special Foundation for Basic Scientific Research of Central Colleges
文摘The effects of low frequency electromagnetic (LFEC) field and ultrasonic (US) field on the microstructures, macrosegregation of alloying elements and the mechanical properties of DC cast AZ80 alloy were studied. The results show that both LFEC and US fields can refine the grains of the billets, which results in the increase in mechanical properties and uniformity of alloying element distribution. The effective refinement takes place on the edge of ingots when LFEC field is applied, while in the center of billets when field US is adopted. Combined the characteristics of LFEC and US fields, a new process for direct-chilling (DC) casting of Mg-electromagnetic-ultrasonic (ECUS) casting is developed, by which the grains are refined significantly and are more uniform in the whole ingots, and the mechanical properties of the ingots are improved.
文摘In Desire Under the Elms, Eugene O＇Neill not only adopts some elements from Greek tragedies, but brings more different ideas for readers, such as supernaturalism, and the degeneration of the tragic heroes or the peasant like language and sets more comic elements. Under his powerful pen, a marvelous drama is displayed before the audience, which combines the traditional elements and modem creations perfectly. This paper aims to explore the important elements in the play and compare those with what are used in Desire Under the Elms so as to draw the conclusion that Eugene O＇Neill not only uses the traditional written skills but also improves the development and inheritance of Greek tragedies.
文摘We tested for fourteen trace elements in samples collected from the Ordovician strata in Datun coal field. The vertical concentration variation of these trace dements is reported. The relationship of the variation to the water-bearing capacity of the Ordovician strata is discussed. The minimum concentration of eleven （of 14 total） trace elements appears in the lower Majiagou formation. The maximum concentrations mainly appear in the Badou and Jiawang formations： eight maxima are located in Badou and four more are in Jiawang. The study of karst development and the water-bearing capacity of Ordovician strata shows that karst is well developed in the Majiagou formation and there is a consequent high water-bearing capacity in this formation： Badou and Jiawang formations are contrary to this situation. The results illustrate that the minimum concentrations of most trace elements within certain Ordovician formations can be taken as strong evidence for the existence of a well developed karst and a high water-bearing capacity.
基金supported by Open-Research Center in Saitama Institute of Technology and University of Science and Technology Liaoning
文摘A new magnesium alloy plate added elements Zn, Sn and In was manufactured by twin-roll continuous casting method to improve the precipitation of AZ91 alloy. The effects of elements addition and casting method on microstructure and mechanical properties of the Mg-Zn-In-Sn alloys were investigated by optical microscopy (OM), transmission electron microscopy (TEM), electron probe micro-analysis (EPMA), X-ray diffractometry (XRD) and energy dispersion spectrograph (EDS). The results show that the Mg-Zn-In-Sn alloy has higher tensile strength and better corrosion protection than the AZ91 alloy. The outstanding precipitation strengthening effect of the alloy is attributed to the small grain size and the hard precipitates between the grain boundaries.
文摘The purpose of this study was to construct bases for exploring the process of skill acquisition from the viewpoint of eye-hand coordination. The information obtained from eye-gaze is closely related to physical movements in any activity. It is important to establish a method to measure eye-hand coordination for extracting skilled elements and understanding the skill acquisition process. Using a system which consists of an eye mark recorder and a three-dimensional location measurement device, a method for measuring eye-hand coordination was proposed on the basis of the simultaneous measurement of eye-gaze and brush tip locations. After describing the measurement algorithm, the eye-hand coordination during calligraphy was exemplified. More concretely, using such a system, an attempt was made to show that the relationship between the line of eye-gaze and the brush tip stroke was different between a novice and an expert. In such a way, we suggested that the proposed method is promising for exploring the process of skill acquisition.
文摘Oxidative stress therapy targeted on ox plays idativ critical role in the pathogenesis of chronic obstructive e stress is of great importance for COPD. However, since pu the lmonary disease （COPD）, so current used antioxidants are not satisfying, scientists have to find more effective antioxidants for COPD. Hydrogen, the most abundant chemical element in the universe, was recently discovered as a novel therapeutic medical gas, and has shown great antioxidant potential in a series of recent published researches for its feature of selectively reducing toxic reactive oxygen species. Based on these findings, we hypothesize that hydrogen gas therapy might be a novel, effective, safe, and economic treatment for COPD patients in one day
基金supported by the National Natural Science Foundation of China(Grant Nos.51010001 and 51001009)the 111 Project(Grant No.B07003)the Program for Changjiang Scholars and Innovative Research Team in University
文摘The effects of Sn and Ga additions on the glass forming ability （GFA） of （A186LasNi9）100_xSnx（x=0, 0.2, 0.3, 0.5, 0.7, 1 and 2 at.%） and （Al86LasNi9）100_xGax（x=0, 0.2, 0.5, 1 and 1.5 at.%） alloys were systematically investigated. Unlike common microal- loying methods, both Sn and Ga have a positive heat of mixing with the main component of A1. Our analysis confirmed that proper Sn addition can suppress the strong formation of a-A1 and enhance the GFA due to the positive heat of mixing between Sn and AI and the large difference in their atomic sizes. While the addition of Ga to the base alloy acted as the nucleation cites for ct-Al and accelerated precipitation of the ct-A1 phase, thus deteriorating the GFA.
基金supported by the National Natural Science Foundation of China (Grant No. 10972015)
文摘Using the concept of base forces as state variables,a new finite element method-the base force element method (BFEM) on complementary energy principle for linear elasticity problems is presented.Firstly,an explicit expression of compliance matrix for an element is derived through base forces by dyadic vectors.Then,the explicit control equations of finite element method of complementary energy principle are derived using Lagrange multiplier method.Thereafter,the base forces element procedure for linear elasticity is developed.Finally,several examples are analyzed to illustrate the reliability and accuracy of the formulation and the procedure.
基金Project supported by the National Natural Science Foundation of China (No. 51178414)the Science Foundation of Zhejiang Province (No. Y1110438), China
文摘A type of hollow cylinder joints connected with H-shaped beams is proposed for spatial structures. Based on von Mises yield criterion and perfect elasto-plasticity model, a series of finite element models of the joints is established, in which the effect of geometric nonlinearity is taken into account. Then mechanical behavior and load-carrying capacity of the joints were investigated, which were subjected to axial load, in- and out-plane bending moments, and their combinations. The results show that the ultimate loads of the joints are determined by the maximum displacement. Furthermore, the case of one joint connected with multiple beams was discussed. Experiments on a set of typical full-scale joints were conducted to understand the structural behavior and the failure mechanism of joint, and also to validate the finite element models. Finally, the practical calculation method was established through finite elements analysis (FEA) results and numerical fitting. The results show that the joints are more ductile and materially economical than welded hollow spherical joints, and the practical calculation method can provide a reference for direct design and the revision of relevant design codes.
基金supported by the National Basic Research Program of China(2007CB613704)
文摘By means of first-principles calculations,we have investigated the effects of rare earth elements (REEs) on the structures and mechanical properties of magnesium.The lattice parameters,elastic constants,bulk moduli,shear moduli,Young's moduli and anisotropic parameter of these solid solutions have been calculated and analyzed.The nearest-neighbor distance between Mg and the REEs is also analyzed to explore the correlation with the bulk moduli.The results show that the 4f-electrons and atomic radii play an important role in the strengthening process.The anomalies of the lattice parameters and mechanical properties at Eu and Yb are due to the half-filled and full-filled 4f-electron orbital states.Finally,the increase of directional bonding character near the alloying elements may account for the anisotropy and brittleness of these magnesium alloys.
