Influence of Li2Sb Additions on Microstructure and Mechanical Properties of Al-20Mg2Si Alloy.

It is found that Li2Sb compound can act as the nucleus of primary Mg2Si during solidification, by which the particle size of primary Mg2Si decreased from ~300 to ~15-25 µm. Owing to the synergistic effect of the Li2Sb nucleus and adsorption-poisoning of Li atoms, the effect of complex modification of Li-Sb on primary Mg2Si was better than that of single modification of Li or Sb. When Li-Sb content increased from 0 to 0.2 and further to 0.5 wt.%, coarse dendrite changed to defective truncated octahedron and finally to perfect truncated octahedral shape. With the addition of Li and Sb, ultimate compression strength (UCS) of Al-20Mg2Si alloys increased from ~283 to ~341 MPa and the yield strength (YS) at 0.2% offset increased from ~112 to ~179 MPa while almost no change was seen in the uniform elongation. Our study offers a simple method to control the morphology and size of primary Mg2Si, which will inspire developing new Al-Mg-Si alloys with improved mechanical properties.

Effect of Pre-Oxidation Treatment of Nano-SiC Particulates on Microstructure and Mechanical Properties of SiC/Mg-8Al-1Sn Composites Fabricated by Powder Metallurgy Combined with Hot Extrusion.

Nano-SiC particulates (n-SiCp) reinforced Mg-8Al-1Sn (AT81) composites with different pre-oxidation parameters were fabricated by powder metallurgy (P/M) process combined with hot extrusion. The effects of pre-oxidization treatment of n-SiCp on the microstructure and tensile properties of 0.5 vol % n-SiCp/AT81 composites were investigated accordingly. The distribution of n-SiCp with different pre-oxidation parameters was homogeneous in the composites. Moreover, it was found that a thin MgAl2O4 layer formed at the interface when the n-SiCp were pre-oxidized at 1073 K for 2 h, while the MgAl2O4 layer became much thicker with pre-oxidization temperature increasing to 1273 K for 2 h. After an appropriate pre-oxidization treatment of n-SiCp at 1073 K for 2 h, the as-extruded 0.5 vol % n-SiCp/AT81 composites exhibited an enhanced strength. It was found that the yield strength (YS) and ultimate tensile strength (UTS) increased from 168 MPa and 311 MPa to 255 MPa and 393 MPa compared with the as-extruded AT81 alloy, reflecting 51.8% and 26.4% increments, respectively. The improvement of mechanical properties should be mainly attributed to the grain refinement and homogeneous distribution of n-SiCp in the composites. Moreover, a well-bonded interface and the formation of an appropriate amount of interfacial product (MgAl2O4) benefited the material's mechanical properties.

Partially matched related donor transplantation can achieve outcomes comparable with unrelated donor transplantation for patients with hematologic malignancies.

PURPOSE: The study aimed to compare the outcomes of patients undergoing hematopoietic stem cell transplantation (HSCT) from partially matched related donors (PMRD) and unrelated donors (URD) for hematologic malignancies without the use of in vitro T cell depletion. EXPERIMENTAL DESIGN: HSCT was done on 297 consecutive patients from URDs (n = 78) and PMRDs (n = 219) during the same time period. Incidences of graft-versus-host disease (GVHD), relapse, nonrelapse mortality, overall survival, and leukemia-free survival between the PMRD and URD groups were compared. RESULTS: All patients achieved full engraftment. The cumct65ulative incidences of grades II to IV acute GVHD in the PMRD and URD cohorts were 47% [95% confidence interval (95% CI), 33-62%] versus 31% (CI, 20-42%; P = 0.033), with a relative risk of 1.72 (95% CI, 1.01-2.94; P = 0.046). The incidence of chronic GVHD did not differ significantly between the two cohorts (P = 0.17). The 2-year incidences of nonrelapse mortality and relapse were 20% (CI, 15-26%) versus 18% (CI, 10-27%), with P = 0.98, and 12% (CI, 8-16%) versus 18% (CI, 10-27%), with P = 0.12, for the PMRD versus the URD cohort, respectively. The 4-year overall survival and leukemia-free survival were 74% (CI, 67-80%) versus 74% (CI, 62-85%), with P = 0.98, and 67% (CI, 59-75%) versus 61% (CI, 47-74%), with P = 0.74, respectively. CONCLUSIONS: Our comparisons show that every major end point, including relapse, nonrelapse mortality, overall survival, and leukemia-free survival, was comparable between the PMRD and the URD groups.

HLA-mismatched/haploidentical hematopoietic stem cell transplantation without in vitro T cell depletion for chronic myeloid leukemia: improved outcomes in patients in accelerated phase and blast crisis phase.

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only proven curative therapy for chronic myeloid leukemia (CML), but lack of human leukocyte antigen (HLA)-matched sibling or unrelated donors has restricted its application. Recently, we developed an effective method for haploidentical allo-HSCT achieving comparable outcomes to HLA-identical transplantation. AIM: To evaluate the outcomes of CML patients who underwent haploidentical allo-HSCT. METHODS: Ninety-three patients were treated with a modified busulfan (BU)/cyclophosphamide (CY) 2 regimen, including antithymocyte globulin followed by unmanipulated blood and marrow transplantation. RESULTS: Our data showed that the cumulative incidence of acute graft-versus-host disease (GVHD) was 64.52%, and grade III-IV was 26.45%, 61.79% had chronic GVHD, and 28.93% had extensive chronic GVHD. Non-relapse mortality varied at 8.72% (100 days), 20.72% (1 year) and 20.72% (2 years). Probability of 1-year and 4-year leukemia-free survival was similar in chronic phase (CP) 1, CP2/CR2, accelerated phase, and blast crisis patients. Probability of 4-year overall survival varied as 76.5% (CP1), 85.7% (CP2/CR2), 73.3% (accelerated phase), and 61.5% (blast crisis). Multivariate analysis indicated that factors affecting transplantation outcomes were HLA-B+DR mismatches versus others for II-III acute GVHD and III-IV acute GVHD, the stage of disease at transplantation for relapse, and the time from diagnosis to transplantation for leukemia-free survival, overall survival, and transplantation-related mortality. In our protocol, survival of HSCT for advanced CML was similar to stable stage. CONCLUSIONS: For patients lacking an HLA-identical related donor, haploidentical relatives are alternative HSCT donors.