As-cast and heat-treated 400-18 ductile iron （DI） grade was obtained in different foundry conditions, as metallic charge, Mg-treatment alloy and inoculation. It was found that the Pearlitic Influence Factor （P） an...As-cast and heat-treated 400-18 ductile iron （DI） grade was obtained in different foundry conditions, as metallic charge, Mg-treatment alloy and inoculation. It was found that the Pearlitic Influence Factor （P） and Anti- nodulizing Complex Factor （K1） have an important influence on property of DI, depending on the Mn and P level, the metallurgical quality of iron melt, rare earth （RE） and inoculation. It was also found that the influence of Mn is depended on the phosphorus and residual elements level in ductile iron. Less than 0.03%P and 0.2%Mn and P〈2.0 are the basic conditions to obtain as-cast ferritic structure. At the same lower level of Mn and P, the increasing of residual elements （P〉2.0） determines presence of pearlite in as-cast structure, while ferrite structure is obtained after a short annealing heat treatment. Lower level of phosphorus （P〈0.025%） and residual elements （Px〈2.0） allow to use relative high Mn content （0.32%-0.38%）, in condition of ferritic structure, including in as-cast state. High P （0.04%- 0.045%） and Mn （0.25%-0.35%） content stabilized peadite, especially at lower level of residual elements （P 〈2.0）. Antinodulizing action of elements was counteracted up to K1=2.0 level, by RE included in Mg-treatment alloy, which are beneficial for K1〈1.2 and compulsory for K1〉1.2. Si has a significant influence on the mechanical properties of heat treated ductile irons： an important decreasing of elongation level and a moderate increasing of yield and tensile strength and their ratio in 150-170 HB typical hardness field. A typical final chemical composition for as-cast 400-18 ductile iron could include 3.5%-3.7%C, 2.4%-2.5%Si, max.0.18%Mn, max.0.025%P, max.0.01%S, 0.04%-0.05%Mg for Px〈1.5 and K1〈1.1. High purity pig iron, RE-bearing FeSiMg and powerful inoculant are also recommended.展开更多
The present study focuses on the analysis of free vibrations of axisymmetric functionally graded hollow spheres. The material is assumed to be graded in radial di- rection with a simple power law. Matrix Frrbenious me...The present study focuses on the analysis of free vibrations of axisymmetric functionally graded hollow spheres. The material is assumed to be graded in radial di- rection with a simple power law. Matrix Frrbenious method of extended power series is employed to derive the analytical solutions for displacement, temperature, and stresses. The dispersion relations for the existence of various types of pos- sible modes of vibrations in the considered hollow sphere are derived in a compact form. In order to explore the character- istics of vibrations, the secular equations are further solved by using fixed point iteration numerical technique with the help of MATLAB software. The numerical results have been presented graphically for polymethyl methecrylate materials in respect of natural frequencies, frequency shift, inverse quality factor, displacement, temperature change, and radial stress.展开更多
Objective:To investigate the vasculogenic mimicry formation induced by hypoxia in Ⅱ-Ⅲ human glioma cell and the effect of alphastatin peptide suppressing the hypoxia-induced vasculogenic mimicry formation and the me...Objective:To investigate the vasculogenic mimicry formation induced by hypoxia in Ⅱ-Ⅲ human glioma cell and the effect of alphastatin peptide suppressing the hypoxia-induced vasculogenic mimicry formation and the mechanism.Methods:MTT,Transwell and three-dimentional culture were used to detect the proliferation,migration and tubule formation of SHG44.The expression of vascular endothelial growth factor-α(VEGF-α),erythropoietin-producing hepatocellular carcinoma-A2 (EphA2) and matrix metalloproteinases 2 (MMP2) was detected by RT-PCR and Western blotting analysis.Results:The OD 490 in hypoxia group was 0.60±0.06 and in control group was 0.46±0.05.The number of cell migration was 178.71±18.81 in hypoxia group and 85.86±17.92 in control group.The tubule formation was 56.80±12.21 in hypoxia group and 4.20±2.62 in control group.The proliferation,migration and tubule formation in hypoxia group were significantly higher than that in control group.The expression of VEGF-α,EphA2 and MMP2 was upregulated in hypoxia.When various concentrations of alphastatin (100,1 000,10 000 nmol/L) were added to hypoxia group,the numbers of cell migration were 142.57±12.12,92.71±17.68,30.00±7.72 and the tubule formation were 47.71±10.58,18.86±8.40,8.43±5.62.The cell migration and tubule formation were significantly suppressed by alphastatin in a dose-dependent manner.In alphastatin group,the phosphorylation of EphA2 protein (P=0.037,F=4.629) and activation of MMP2 protein (P=0.005,F=9.331) were significantly suppressed but there was no change in VEGF-α protein.Conclusion:Ⅱ-Ⅲ human glioma cell is able to form vasculogenic mimicry induced by hypoxia and alphastatin peptide can suppress the hypoxia-induced vasculogenic mimicry.VEGF-α induced EphA2 phospharilation and MMP2 activation maybe the key pathway to form vasculogenic mimicry.展开更多
This paper deals with the rotational flow of a generalized second grade fluid, within a circular cylinder, due to a torsional shear stress. The fractional calculus approach in the constitutive relationship model of a ...This paper deals with the rotational flow of a generalized second grade fluid, within a circular cylinder, due to a torsional shear stress. The fractional calculus approach in the constitutive relationship model of a second grade fluid is introduced. The velocity field and the resulting shear stress are determined by means of the Laplace and finite Hankel transforms to satisfy all imposed initial and boundary conditions. The solutions corresponding to second grade fluids as well as those for Newtonian fluids are obtained as limiting cases of our general solutions. The influence of the fractional coefficient on the velocity of the fluid is also analyzed by graphical illustrations.展开更多
文摘As-cast and heat-treated 400-18 ductile iron （DI） grade was obtained in different foundry conditions, as metallic charge, Mg-treatment alloy and inoculation. It was found that the Pearlitic Influence Factor （P） and Anti- nodulizing Complex Factor （K1） have an important influence on property of DI, depending on the Mn and P level, the metallurgical quality of iron melt, rare earth （RE） and inoculation. It was also found that the influence of Mn is depended on the phosphorus and residual elements level in ductile iron. Less than 0.03%P and 0.2%Mn and P〈2.0 are the basic conditions to obtain as-cast ferritic structure. At the same lower level of Mn and P, the increasing of residual elements （P〉2.0） determines presence of pearlite in as-cast structure, while ferrite structure is obtained after a short annealing heat treatment. Lower level of phosphorus （P〈0.025%） and residual elements （Px〈2.0） allow to use relative high Mn content （0.32%-0.38%）, in condition of ferritic structure, including in as-cast state. High P （0.04%- 0.045%） and Mn （0.25%-0.35%） content stabilized peadite, especially at lower level of residual elements （P 〈2.0）. Antinodulizing action of elements was counteracted up to K1=2.0 level, by RE included in Mg-treatment alloy, which are beneficial for K1〈1.2 and compulsory for K1〉1.2. Si has a significant influence on the mechanical properties of heat treated ductile irons： an important decreasing of elongation level and a moderate increasing of yield and tensile strength and their ratio in 150-170 HB typical hardness field. A typical final chemical composition for as-cast 400-18 ductile iron could include 3.5%-3.7%C, 2.4%-2.5%Si, max.0.18%Mn, max.0.025%P, max.0.01%S, 0.04%-0.05%Mg for Px〈1.5 and K1〈1.1. High purity pig iron, RE-bearing FeSiMg and powerful inoculant are also recommended.
基金support provided by CSIR New Delhi via project grant No.25 (0184)/10/EMR–II
文摘The present study focuses on the analysis of free vibrations of axisymmetric functionally graded hollow spheres. The material is assumed to be graded in radial di- rection with a simple power law. Matrix Frrbenious method of extended power series is employed to derive the analytical solutions for displacement, temperature, and stresses. The dispersion relations for the existence of various types of pos- sible modes of vibrations in the considered hollow sphere are derived in a compact form. In order to explore the character- istics of vibrations, the secular equations are further solved by using fixed point iteration numerical technique with the help of MATLAB software. The numerical results have been presented graphically for polymethyl methecrylate materials in respect of natural frequencies, frequency shift, inverse quality factor, displacement, temperature change, and radial stress.
基金Supported in Part by a Grant from the National Nature Science Foundation of China(No.30672126)
文摘Objective:To investigate the vasculogenic mimicry formation induced by hypoxia in Ⅱ-Ⅲ human glioma cell and the effect of alphastatin peptide suppressing the hypoxia-induced vasculogenic mimicry formation and the mechanism.Methods:MTT,Transwell and three-dimentional culture were used to detect the proliferation,migration and tubule formation of SHG44.The expression of vascular endothelial growth factor-α(VEGF-α),erythropoietin-producing hepatocellular carcinoma-A2 (EphA2) and matrix metalloproteinases 2 (MMP2) was detected by RT-PCR and Western blotting analysis.Results:The OD 490 in hypoxia group was 0.60±0.06 and in control group was 0.46±0.05.The number of cell migration was 178.71±18.81 in hypoxia group and 85.86±17.92 in control group.The tubule formation was 56.80±12.21 in hypoxia group and 4.20±2.62 in control group.The proliferation,migration and tubule formation in hypoxia group were significantly higher than that in control group.The expression of VEGF-α,EphA2 and MMP2 was upregulated in hypoxia.When various concentrations of alphastatin (100,1 000,10 000 nmol/L) were added to hypoxia group,the numbers of cell migration were 142.57±12.12,92.71±17.68,30.00±7.72 and the tubule formation were 47.71±10.58,18.86±8.40,8.43±5.62.The cell migration and tubule formation were significantly suppressed by alphastatin in a dose-dependent manner.In alphastatin group,the phosphorylation of EphA2 protein (P=0.037,F=4.629) and activation of MMP2 protein (P=0.005,F=9.331) were significantly suppressed but there was no change in VEGF-α protein.Conclusion:Ⅱ-Ⅲ human glioma cell is able to form vasculogenic mimicry induced by hypoxia and alphastatin peptide can suppress the hypoxia-induced vasculogenic mimicry.VEGF-α induced EphA2 phospharilation and MMP2 activation maybe the key pathway to form vasculogenic mimicry.
文摘This paper deals with the rotational flow of a generalized second grade fluid, within a circular cylinder, due to a torsional shear stress. The fractional calculus approach in the constitutive relationship model of a second grade fluid is introduced. The velocity field and the resulting shear stress are determined by means of the Laplace and finite Hankel transforms to satisfy all imposed initial and boundary conditions. The solutions corresponding to second grade fluids as well as those for Newtonian fluids are obtained as limiting cases of our general solutions. The influence of the fractional coefficient on the velocity of the fluid is also analyzed by graphical illustrations.
