In this context,a testing system to understand rock fracturing processes induced by different dynamic disturbances under true triaxial compression was developed.The system is mainly composed of a static loading subsys...In this context,a testing system to understand rock fracturing processes induced by different dynamic disturbances under true triaxial compression was developed.The system is mainly composed of a static loading subsystem,a dynamic loading subsystem,a specimen box subsystem,and a data measurement subsystem.The static loading subsystem uses low stiffness loss frame structure technology,which greatly improves the frame stiffness in the three principal stress directions(up to 20 GN/m)and ensures the demand of the disturbance experiment in both the prepeak and postpeak stages.The disturbance loads with frequency of 0e20 Hz and stress level of 0e30 MPa were applied using large flow parallel oil source technology characterized with high heat dissipation efficiency.For the disturbance loads with frequency of 100e500 Hz and stress level of 0e30 MPa,they were realized by using high-frequency and centimeter-per-second-scale low-speed disturbance rod technology.Three rigid self-stabilizing specimen boxes were utilized to provide support for the specimen and deformation sensors,ensuring the stability and accuracy of the data obtained.To verify the performance of the true triaxial test system,disturbance experiments were conducted on granite specimens.The results show that the experimental device satisfies the requirements of original design,with an excellent repeatability and reliable testing results.展开更多
The chemical short-range order of Al-Fe-Ce amorphous alloy was studied by means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It is found that the prepeak position in X-ray diffraction intens...The chemical short-range order of Al-Fe-Ce amorphous alloy was studied by means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It is found that the prepeak position in X-ray diffraction intensity curve shifts to higher angles as the content of Fe increases, but it shifts to smaller angles as the content of Ce increases. The crystallization character of the amorphous alloy changes with the variation of the content of Fe and Ce. Ce can improve the interaction between atoms and the capacity of compound formation, so it is favorable to Al-based glass formability.展开更多
X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were usedto investigate the crystallization process of amorphous Al_(90)TM_xCe_(10-x), (atom fraction inpercent; TM = Fe or Ni; x = 3, 5) alloys. Agi...X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were usedto investigate the crystallization process of amorphous Al_(90)TM_xCe_(10-x), (atom fraction inpercent; TM = Fe or Ni; x = 3, 5) alloys. Aging effects were examined by X-ray diffraction. Thestructure corresponding to the prepeak for the amorphous Al_(90)Fe_5Ce_5 alloy is more stable thanthe amorphous matrix, but it is not stable for amorphous Al_(90)Ni_5Ce_5 alloy during the firstcrystallization stage and even decomposes at room temperature. Although both Al-Ni and Al-Fe havestrong chemical bonding, the crystallization onset temperature of amorphous Al-Fe-Ce alloys is muchhigher than that of amorphous Al-Ni-Ce alloys, which is likely caused by the different stability ofthe structure corresponding to the prepeak. The crystallization onset temperature increases as Ce/Niratio increases in amorphous Al_(90)Ni_xCe_(10-x) alloys, whereas it decreases as Ce/Fe ratioincreases in amorphous Al_(90)Fe_xCe_(10-x) alloys. A better atomic packing produces as Ce contentincreases because of the size mismatch in Al-Ni-Ce systems and as Fe content increases because ofthe increasing Fe central structural units.展开更多
The complexation of Cd with cysteine has been investigated at pH ~9, and in constant ionic medium 0.59 M NaNO3 and borate buffer. Reduction signals of the hydrated Cd2+ and Cd-cysteinate complex were resolved on the p...The complexation of Cd with cysteine has been investigated at pH ~9, and in constant ionic medium 0.59 M NaNO3 and borate buffer. Reduction signals of the hydrated Cd2+ and Cd-cysteinate complex were resolved on the potential scale during amperometric titration of 2 × 10-6 M Cd2+ with cysteine and cysteine with Cd2+, in a differential pulse (DP) mode on HMDE. The 1:1 molar ratio of Cd2+ to cysteine, and cysteine to Cd2+, was defined for Cd-cysteinate complex formed under the defined conditions. The appearance of the prepeak on the Cd-cysteinate reduction signal is showed, as the result of cysteine adsorption in reduced form. From the mass balance equations, the stoichiometric stability constants of Cd-cysteinate complex were calculated. Under various experimental conditions, comparable log K values were obtained. The grand average log K = 7.83 M-1 refers to 0.59 M ionic strength and 23℃.展开更多
The molecular-dynamics (MD) simulation was carried out to investigate the structure of medium-range order (MRO) of a liquid Al 5Fe 2 alloy. Prepeak is observed in the structure factor S(Q), which is considered as the ...The molecular-dynamics (MD) simulation was carried out to investigate the structure of medium-range order (MRO) of a liquid Al 5Fe 2 alloy. Prepeak is observed in the structure factor S(Q), which is considered as the signature of MRO. Results from MD simulation and experiment agree well with each other, which proves reliability of the simulation. It is found from the calculated Ashcroft-Langreth structure factors that there exists strong interactional force between atom Al and Fe, which results in the great concentration fluctuation, i.e. the chemical order, in the liquid Al 5Fe 2. Both the chemical order parameter, α , and the Bhatis-Thornton(BT)structure factors indicate the preference for unlike-neighbor bonds. It is seen from the low-Q domain of S(Q) and the concentration-concentration structure factor S CC(Q) that the prepeak mainly comes from the first peak of S CC(Q). The structural model, which reflects the characteristic of MRO, is also constructed .展开更多
基金This study was financially supported by the National Natural Science Foundation of China(Grant No.51839003),for which we are grateful.
文摘In this context,a testing system to understand rock fracturing processes induced by different dynamic disturbances under true triaxial compression was developed.The system is mainly composed of a static loading subsystem,a dynamic loading subsystem,a specimen box subsystem,and a data measurement subsystem.The static loading subsystem uses low stiffness loss frame structure technology,which greatly improves the frame stiffness in the three principal stress directions(up to 20 GN/m)and ensures the demand of the disturbance experiment in both the prepeak and postpeak stages.The disturbance loads with frequency of 0e20 Hz and stress level of 0e30 MPa were applied using large flow parallel oil source technology characterized with high heat dissipation efficiency.For the disturbance loads with frequency of 100e500 Hz and stress level of 0e30 MPa,they were realized by using high-frequency and centimeter-per-second-scale low-speed disturbance rod technology.Three rigid self-stabilizing specimen boxes were utilized to provide support for the specimen and deformation sensors,ensuring the stability and accuracy of the data obtained.To verify the performance of the true triaxial test system,disturbance experiments were conducted on granite specimens.The results show that the experimental device satisfies the requirements of original design,with an excellent repeatability and reliable testing results.
文摘The chemical short-range order of Al-Fe-Ce amorphous alloy was studied by means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It is found that the prepeak position in X-ray diffraction intensity curve shifts to higher angles as the content of Fe increases, but it shifts to smaller angles as the content of Ce increases. The crystallization character of the amorphous alloy changes with the variation of the content of Fe and Ce. Ce can improve the interaction between atoms and the capacity of compound formation, so it is favorable to Al-based glass formability.
基金This work was financially supported by the Natural Science Foundation of Shandong Province (No. Y2000b02)
文摘X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were usedto investigate the crystallization process of amorphous Al_(90)TM_xCe_(10-x), (atom fraction inpercent; TM = Fe or Ni; x = 3, 5) alloys. Aging effects were examined by X-ray diffraction. Thestructure corresponding to the prepeak for the amorphous Al_(90)Fe_5Ce_5 alloy is more stable thanthe amorphous matrix, but it is not stable for amorphous Al_(90)Ni_5Ce_5 alloy during the firstcrystallization stage and even decomposes at room temperature. Although both Al-Ni and Al-Fe havestrong chemical bonding, the crystallization onset temperature of amorphous Al-Fe-Ce alloys is muchhigher than that of amorphous Al-Ni-Ce alloys, which is likely caused by the different stability ofthe structure corresponding to the prepeak. The crystallization onset temperature increases as Ce/Niratio increases in amorphous Al_(90)Ni_xCe_(10-x) alloys, whereas it decreases as Ce/Fe ratioincreases in amorphous Al_(90)Fe_xCe_(10-x) alloys. A better atomic packing produces as Ce contentincreases because of the size mismatch in Al-Ni-Ce systems and as Fe content increases because ofthe increasing Fe central structural units.
文摘The complexation of Cd with cysteine has been investigated at pH ~9, and in constant ionic medium 0.59 M NaNO3 and borate buffer. Reduction signals of the hydrated Cd2+ and Cd-cysteinate complex were resolved on the potential scale during amperometric titration of 2 × 10-6 M Cd2+ with cysteine and cysteine with Cd2+, in a differential pulse (DP) mode on HMDE. The 1:1 molar ratio of Cd2+ to cysteine, and cysteine to Cd2+, was defined for Cd-cysteinate complex formed under the defined conditions. The appearance of the prepeak on the Cd-cysteinate reduction signal is showed, as the result of cysteine adsorption in reduced form. From the mass balance equations, the stoichiometric stability constants of Cd-cysteinate complex were calculated. Under various experimental conditions, comparable log K values were obtained. The grand average log K = 7.83 M-1 refers to 0.59 M ionic strength and 23℃.
文摘The molecular-dynamics (MD) simulation was carried out to investigate the structure of medium-range order (MRO) of a liquid Al 5Fe 2 alloy. Prepeak is observed in the structure factor S(Q), which is considered as the signature of MRO. Results from MD simulation and experiment agree well with each other, which proves reliability of the simulation. It is found from the calculated Ashcroft-Langreth structure factors that there exists strong interactional force between atom Al and Fe, which results in the great concentration fluctuation, i.e. the chemical order, in the liquid Al 5Fe 2. Both the chemical order parameter, α , and the Bhatis-Thornton(BT)structure factors indicate the preference for unlike-neighbor bonds. It is seen from the low-Q domain of S(Q) and the concentration-concentration structure factor S CC(Q) that the prepeak mainly comes from the first peak of S CC(Q). The structural model, which reflects the characteristic of MRO, is also constructed .
