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The strength and plasticity trade-off in metal materials can be effectively addressed by Eutectic High-Entropy Alloys (EHEAs) through the realization of heterogeneous biphase layered structures at both micrometer and nanometer scales. In this work, a series of (CoCrFeNi)88NbxW(12-x)EHEAs were prepared, and the effects of the synergistic of Nb and W elements on the microstructure and mechanical properties of CoCrFeNi High-Entropy Alloys (HEAs) were investigated. With the increase of Nb content and the decrease of W content, the microstructure of the alloy underwent three changes, from Face Center Cubic (FCC) + μ biphase to FCC + μ + Laves triple phase, and finally to FCC + Laves biphase. The strength of the alloy increases, but the compression rate decreases. Among these alloys, (CoCrFeNi)88Nb10W2alloy exhibits exceptional mechanical properties. The synergistic effect of precipitation strengthening and grain boundary strengthening makes the yield strength, fracture strength, and plastic strain of the alloy are 1568 MPa, 2516 MPa, and 32 % respectively. In addition, in the CoCrFeNi HEAs, the weighted average atomic radius ratio (rm‾/rQ) is used to further precise the phase selection law of Laves phase and μ phase. When rm‾/rQ< 1.112, HEAs forms the μ phase, when 1.112 ≤ rm‾/rQ≤ 1.14, HEAs forms the Laves + μ biphase, when rm‾/rQ> 1.14, HEAs forms the Laves phase. The results can provide a basis for synergistic strengthening and phase selection of CoCrFeNi HEAs.

Continuous jet impact on a rotating wall is mainly used in the field of mechanical heating or cooling. In order to clarify the influence of different parameters on the flow field structure of the rotating wall, the method of jet and rotating fluid coupling in the near-wall area is adopted in this study. Different turbulence models are used to compare with the PIV experiment in the study of continuous jet impact on the static wall, and the Wray–Agarwal turbulence model is used for research. The flow field characteristics and the near-wall velocity distribution of the continuous jet impinging on the rotating disk at different speeds and impacting heights are focused. The results show that with the increasing rotation speed of the disk, the center of the vortex gradually approaches the wall of the disk until it reaches the edge of the disk. When the radial position is large, the radial and circumferential components of the velocity near the wall gradually increase linearly. The increase in the impacting height will lead to irregular vortex structure far away from the impacting wall. The research of jet impinging on rotating wall has important engineering application background and academic value.

Aim:Both pancreatic stellate cells (PSCs) and the stromal cell-derived factor-1(SDF-1)/CXCR4 receptor ligand system have important roles in pancreatic cancer progression. This study set out to detect if PSCs express SDF-1 and promote the invasion of pancreatic cancer through the SDF-1/CXCR4 receptor ligand axis. Methods:RT-PCR was performed to detect the expression of SDF-1 and CXCR4 in PSCs, pancreatic cancer lines and cancer tissue samples. ELISA was used to investigate the concentration of SDF-1 in PSC supernatants. An MTT assay was applied to detect the proliferation of pancreatic cancer cells. A transwell chamber migration assay was employed to detect the migration of AsPC-1 cells. An in vitro invasion assay was used to detect the invasion of AsPC-1 cells. Results:CXCR4 expression was detected in PSCs; AsPC-1, SW1990 and BxPC-3 cancer cells; and cancer tissues. SDF-1 was detected in PSCs and cancer tissues, but not in AsPC-1, SW1990 and BxPC-3 cells. SDF-1a protein was found in PSC supernatants. PSC-conditioned media can promote the proliferation, migration and invasion of pancreatic cancer cells. SDF-1 neutralizing antibody or AMD3100 can significantly inhibit these promotive effects. Conclusion:PSCs can secrete SDF-1 and increase the invasion of pancreatic cancer cells through the SDF-1/CXCR4 axis.

AbstractAim:Both pancreatic stellate cells (PSCs) and the stromal cell-derived factor-1(SDF-1)/CXCR4 receptor ligand system have important roles in pancreatic cancer progression. This study set out to detect if PSCs express SDF-1 and promote the invasion of pancreatic cancer through the SDF-1/CXCR4 receptor ligand axis. Methods:RT-PCR was performed to detect the expression of SDF-1 and CXCR4 in PSCs, pancreatic cancer lines and cancer tissue samples. ELISA was used to investigate the concentration of SDF-1 in PSC supernatants. An MTT assay was applied to detect the proliferation of pancreatic cancer cells. A transwell chamber migration assay was employed to detect the migration of AsPC-1 cells. An in vitro invasion assay was used to detect the invasion of AsPC-1 cells. Results:CXCR4 expression was detected in PSCs; AsPC-1, SW1990 and BxPC-3 cancer cells; and cancer tissues. SDF-1 was detected in PSCs and cancer tissues, but not in AsPC-1, SW1990 and BxPC-3 cells. SDF-1α protein was found in PSC supernatants. PSC-conditioned media can promote the proliferation, migration and invasion of pancreatic cancer cells. SDF-1 neutralizing antibody or AMD3100 can significantly inhibit these promotive effects. Conclusion:PSCs can secrete SDF-1 and increase the invasion of pancreatic cancer cells through the SDF-1/CXCR4 axis.Copyright © 2010 S. Karger AG, Basel and IAP