Surprising coercivity increment of sintered Ce–Fe–B magnets: Ce partly substituted by La

Aiming at refining the unideal microstructure and magnetic performance of sintered Ce–Fe–B magnets, La was introduced into the alloy. The role of La addition on the microstructure and magnetic properties revolution of Ce–Fe–B magnet was investigated in this study. The results suggested that La substitution could obstacle the phase structure deterioration during sintering process and maintained high 2:14:1 phase proportion. Meanwhile, uniform grain size and continuous RE-rich grain boundary phase appeared with La addition, which could be attributed to the segregation behaviors of La element and enhanced oxidation resistance with more 2:14:1 phase. The coercivity showed noteworthy increase from 2.93 kOe to 4.78 kOe under the synergetic effect of maintained 2:14:1 phase proportion, uniform RE2Fe[Formula: see text]B grain and even RE-rich phase distribution. This work indicated that La could act as a useful additive to obtain the cost-effective magnetic materials with moderate performance.

Microstructures and Properties of Sn2.5Ag0.7Cu0.1RE Composite Solders Reinforced with Cu-Coated Graphene Nanosheets Synthesized by Pyrolysis

Composite solder is a promising route to improve the properties and reliability of Sn-based lead-free solder. In this study, Cu-coated graphene nanosheets (Cu-GNSs) were synthesized using pyrolysis. Cu-GNSs reinforced Sn2.5Ag0.7Cu0.1RE composite lead-free solders were prepared via powder metallurgy. The size, distribution, and adsorption type of Cu nanoparticles on the GNSs were studied. The relation of the Cu-GNSs content and microstructure to the physical, wettability, and mechanical properties of composite solders was discussed. The results show that Cu nanoparticles (with a mean size of 13 nm) present uniform distribution and effective chemisorptions on the GNS. Microstructural evolution of composite solders is dependent on the addition of Cu-GNSs. With increasing Cu-GNSs addition, β-Sn grains become finer and the eutectic phase proportion becomes larger, while the morphology of the eutectic phase transforms from dispersion to network-type. The improvement of the tensile strength of the composite solder can be attributed to grain refinement and load transfer. While the existence of Cu-GNSs can effectively improve the wettability and slightly change the melting point, it can also lead to the decline of elongation and electrical conductivity of the composite solder.

Ultrasonic-induced nanocomposites with anatase@amorphous TiO2 core–shell structure and their photocatalytic activity

Anatase@amorphous TiO2 core–shell structure nanocomposites were obtained through ultrasonic irradiation on hydrothermally synthesized anatase nanocrystals. The optimized research of the phase proportion revealed the effects of disorder phase.

Kinetics of γ-Mg17Al12 Phase Dissolution and its Effect on Room Temperature Tensile Properties in As-Cast AZ80 Magnesium Alloy

As-cast AZ80 magnesium alloy consists of α-Mg, eutectic product of α-Mg and γ-Mg17Al12, with the latter present in the form of partially and fully divorce eutectic. There occurs dissolution of harder γ-Mg17Al12 phase during homogenization treatment at 400 ᵒ and 439 ᵒC. The proportion of the α-Mg and γ-Mg17Al12 phase was varied by solutionizing the alloy for various lengths of time at these temperatures, in order to investigate the kinetics of phase transformation and to evaluate the effect of phase proportion, size and morphology on room temperature tensile properties. It was found that the yield strength decreases with the increase in solutionizing temperature from 400ᵒ to 439 ᵒC and at the same time, ductility in general increases with the increasing solutionizing temperature. The variation in tensile properties and the nature of fractographs were analyzed in terms of the effects of microstructure

The In Situ Polymerization and Characterization of PA6/LiCl Composites

PA6/LiCl composites were synthesized by in situ anionic polymerization based on the interaction between the inorganic salts and PA6. Sodium hydroxide as initiator and N-acetylcaprolactam as activator were used in the preparation of PA6/LiCl composites with variety of LiCl content. X-ray diffraction (XRD) and differential scanning calorimeter (DSC) testing results showed that both of degree of crystallinity and melting temperature of the composites were decreased under the influence of LiCl. And theγcrystal phase proportion increased with increasing the LiCl content to appropriate amount.

The Effect of Cooling Rate on Bainite Phase Formation in Austempered Nickel-Molybdenum Gray Cast Iron

Taking into account the importance of the amount of bainite phase on the microstructure of cast irons and its influence on the improvement of mechanical properties, this research selected an alloy of gray cast iron containing Nickel-Molybdenum and conducted the austenitising and austempering processes at 900°C and 400°C for 60 minutes, respectively. The way of bainite phase formation and the effect of sample thickness, that is, cooling rate, were examined by selecting a standard staircase sample. The results indicated that, by increasing the cross sections of samples, the martensite percentage decreases and the phase proportion of bainitic ferrite increases.

Bmi-1 Is Dispensable for the Development of Acute Myeloid Leukemia Mediated by MLL-AF9

Abstract 63 The Polycomb group 1 gene Bmi1 has been shown to be required for several normal adult stem cell types, including hematopoietic stem cells. High expression of Bmi1 is correlated with adverse prognosis in human AML and MDS. Bmi1 null murine fetal liver cells transformed with HoxA9 and Meis1 give rise to a primary leukemia of expanding blasts that fails to expand in secondary recipient mice thus demonstrating a defect in leukemia self-renewal (Nature. 2003; 423:255). More recently, Bmi1 has also been shown to bind PML-RARA, and to be required for in vitro replating of PML-RARA immortalized murine colony forming cells (cfc). Our laboratory recently demonstrated that MLL-AF9, a recurrent translocation commonly found in human acute leukemia, more efficiently transforms murine granulocyte macrophage progenitors (GMP) compared to the combination of HoxA9 and Meis1. We decided to test if MLL-AF9 is able to bypass the requirement for Bmi1 previously reported in other murine leukemia models. Lineage marker negative (Lin-) bone marrow cells from WT and Bmi1 −/− mice were transduced with an MSCV-based ecotropic retroviral vector expressing MLL-AF9 and linked via an internal ribosomal entry site (IRES) the selectable marker, GFP. Cells were harvested and injected into 5 sublethally (200 cGy) irradiated NOD/SCID mice per group. All mice developed AML based on GFP expression, spleen size, forward/side scatter profile and surface marker staining (Mac1 positive/Gr1 positive, B220 negative, CD3 negative). Median latency in the WT group was 54 days, whereas mice receiving a graft consisting of Bmi1 −/− cells transduced with MLL-AF9 developed leukemia with a median latency of 89 days. The experiment was repeated with very similar results with median latencies of 50 days (WT group) and 70 days (Bmi1 −/−). To confirm sustained self-renewal, we then proceeded to secondary transplantation experiments. Secondary leukemia developed with similar latency in recipients of primary WT (31.5d) and Bmi1−/− (32d) leukemic bone marrow cells. The experiment was repeated with bone marrow from mice with primary leukemias from the second cohort and again similar latencies were observed (42.5 days in the WT group vs 29.5 days in the Bmi1 −/− group.). Finally we proceeded to tertiary transplantation experiments. All recipients of secondary AML cells developed AML with median latencies of 17.5 d (WT) and 21 d (KO). To compare our results with a system closer to the original studies of leukemogenesis in a Bmi1 −/− background, we chose to transduce lin- bone marrow from WT and Bmi1 −/− with retroviral vectors for HoxA9-IRES-GFP and Meis1-pgk-puro. Both, WT and HoxA9/Meis1 transduced cells replated in in vitro methylcellulose cultures for at least 4 rounds. In the first of 2 in vivo experiments, 5/5 recipients of wild type cells developed acute myeloid leukemia with a median latency of 88 days. In contrast, none of the five recipients of HoxA9/Meis1a transduced Bmi1−/− cells developed leukemia, and these mice were sacrificed 6 months after transplantation. In a second independent experiment, 5/5 recipients of WT HoxA9/Meis1 transduced cells developed AML with a median latency of 62 days. One recipient of Bmi1 −/− cells transduced with HoxA9/Meis1 developed leukemia. One mouse died from a spontaneous lymphoma. The remaining 3 mice in this cohort did not develop leukemia. These findings are consistent with the previously published data and suggest that MLL-AF9 is more efficient in generating AML in Bmi1−/− bone marrow compared to the combination of HoxA9 and Meis1. To further characterize the Bmi1 −/− leukemias, we analyzed expression of the primary Bmi1 target p16 by Western blot. In primary, secondary and tertiary AMLs from Bmi1 −/− mice, derepression of p16 could be demonstrated. We analyzed the cell cycle distribution of cultured tertiary leukemia cells. WT cells showed a S phase proportion of 44–45 percent (n=2), whereas the Bmi1 −/− cells demonstrated a S-phase proportion of 30–38% (n=2). These results demonstrate modest effects of p16 derepression on cell cycle without catastrophic failure to divide. This is mirrored by the in vivo development of secondary and tertiary leukemias in the presence of elevated p16 levels. Preliminary data suggest a similar but less pronounced derepression of p19. Future experiments will focus on the mechanisms that allow MLL-AF9 transduced cells to grow in the presence of derepressed p16 and p19. Disclosures: Armstrong: Epizyme, Inc: Consultancy.