The nucleation and growth of grains in a series of Al-based alloys produced by electrolysis are observed under SEM. The atomic Ti/AI ratios of the nuclei and the distribution of Ti at certain points are analyzed by po...The nucleation and growth of grains in a series of Al-based alloys produced by electrolysis are observed under SEM. The atomic Ti/AI ratios of the nuclei and the distribution of Ti at certain points are analyzed by point EDS. The particles in different atomic Ti/AI ratios might act as the nuclei of α-Al. At the early stage of growth, the spherical Ti-enriched regions might form around these particles within very limited temperature ranges in which the reactions such as the peritectic reactions etc occur. At the latter stage of growth, the dendrites freely develop in the radial orientations, and the concentration of Ti decreases linearly along the dendrite arm and becomes negligible in the region near the periphery of the dendrite. It is believed that the nucleation is closely related with the number and dispersion of primary spherical areas in the melts, and the segregation of Ti leads to the free growth of dendrite, which is necessary for the formation of equiaxial grains.展开更多
OBJECTIVE To investigate the relationship between vascular epithelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) in melanomas and the expressive difference of VEGF and COX-2 between melanomas with and without v...OBJECTIVE To investigate the relationship between vascular epithelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) in melanomas and the expressive difference of VEGF and COX-2 between melanomas with and without vasculogenic mimicry(VM).METHODS Sixty cases of malignant melanomas emoeaaea In paraffin were studied. The tumors were divided into a high-grade malignant group and a low-grade malignant group based on their tumor type, atypia and survival time of the patient. Then tissue microarrays were produced from these paraffin-embedded tumor tissues which were stained for VEGF, COX-2 and PAS. The difference in expression between VEGF and COX-2 in the malignant melanomas was compared using a grid-count. In addition, the tumors were also divided into mimicry and non-mimicry groups based on their PAS staining. Then the differences between the PAS positive and negative areas of the 2 groups were compared.RESULTS In malignant melanomas with VM, VEGF and COX-2 expression was less in tumors in which VM was absent, but VEGF, COX-2 expression in high-grade malignant melanomas was higher than that in low-grade grade malignant melanomas. Expression of VEGF was correlated with COX-2 expression.CONCLUSION VM exists in some high-grade malignant melanomas. The differences and relations between VEGF and COX-2 showed that some high-grade malignant melanomas possess a unique molecular-mechanism of tumor metastasis and blood supply.展开更多
文摘The nucleation and growth of grains in a series of Al-based alloys produced by electrolysis are observed under SEM. The atomic Ti/AI ratios of the nuclei and the distribution of Ti at certain points are analyzed by point EDS. The particles in different atomic Ti/AI ratios might act as the nuclei of α-Al. At the early stage of growth, the spherical Ti-enriched regions might form around these particles within very limited temperature ranges in which the reactions such as the peritectic reactions etc occur. At the latter stage of growth, the dendrites freely develop in the radial orientations, and the concentration of Ti decreases linearly along the dendrite arm and becomes negligible in the region near the periphery of the dendrite. It is believed that the nucleation is closely related with the number and dispersion of primary spherical areas in the melts, and the segregation of Ti leads to the free growth of dendrite, which is necessary for the formation of equiaxial grains.
文摘OBJECTIVE To investigate the relationship between vascular epithelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) in melanomas and the expressive difference of VEGF and COX-2 between melanomas with and without vasculogenic mimicry(VM).METHODS Sixty cases of malignant melanomas emoeaaea In paraffin were studied. The tumors were divided into a high-grade malignant group and a low-grade malignant group based on their tumor type, atypia and survival time of the patient. Then tissue microarrays were produced from these paraffin-embedded tumor tissues which were stained for VEGF, COX-2 and PAS. The difference in expression between VEGF and COX-2 in the malignant melanomas was compared using a grid-count. In addition, the tumors were also divided into mimicry and non-mimicry groups based on their PAS staining. Then the differences between the PAS positive and negative areas of the 2 groups were compared.RESULTS In malignant melanomas with VM, VEGF and COX-2 expression was less in tumors in which VM was absent, but VEGF, COX-2 expression in high-grade malignant melanomas was higher than that in low-grade grade malignant melanomas. Expression of VEGF was correlated with COX-2 expression.CONCLUSION VM exists in some high-grade malignant melanomas. The differences and relations between VEGF and COX-2 showed that some high-grade malignant melanomas possess a unique molecular-mechanism of tumor metastasis and blood supply.
