CoCrFeMnNi high-entropy alloy (HEA) materials were fabricated using mechanical alloying (MA) and spark plasma sintering (SPS). The MA time, SPS temperature, and contaminations strongly affected the ...final microstructure and mechanical properties. Nanocrystal face-centered cubic (FCC) solid solution was made during MA, and the FCC phase maintained as the matrix after SPS at 900 °C and 1100 °C. However, Cr carbides were transformed near the surface due to the carbon contamination. When MA time increased, phase stability of the FCC phase was improved, and the contaminant (ZrO2) from the MA balls was also increased. Ultrafine-grained microstructure was obtained at 60 min MA and 900 °C SPS. On the other hand, the higher SPS temperature and lower levels of contamination were required to achieve tensile ductility. Irregularly distributed ZrO2 particles developed bimodal microstructures.
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•CoCrFeMnNi high-entropy alloys were fabricated using powder metallurgy.•Contaminations highly affected microstructural evolution and mechanical properties.•Phase stability was improved with increasing ball milling time.•UFG microstructure was obtained under a certain condition.
Summary Background Since South Korea reported its first Middle East respiratory syndrome coronavirus (MERS-CoV) cluster on May 20 2015, there had been 186 confirmed cases, 38 deaths, and 16,752 ...suspected cases. Previously published research on South Korea's MERS outbreak has been limited to the early stages when limited data were available. Now that the outbreak has ended, albeit unofficially, a more comprehensive review is appropriate. Methods Data were obtained through the MERS Portal, by the Ministry for Health and Welfare (MOHW), and Korea Centers for Disease Control and Prevention, press releases by MOHW, and reports by the MERS Policy Committee of the Korean Medical Association. Cases were analyzed for general characteristics, exposure source, timeline, and infection generation. Gender, age, and underlying diseases were analyzed for the 38 deaths. Findings Beginning with the index case that infected 28 others, an in-depth analysis was conducted. The average age was 55, a little higher than the global average of 50; as in most other countries, more men than women were affected. The case fatality rate was 19·9%, lower than the global rate of 38.7%, and that ins Saudi Arabia (36·5%). 184 patients were infected nosocomially, while none were intra-community infections. The main underlying diseases were respiratory diseases, cancer, and hypertension. Main contributors to the outbreak were late diagnosis, quarantine failure of “super-spreaders”, familial care-giving and visiting, nondisclosure by patients, poor communication by the Government, inadequate hospital infection management, and "doctor shopping”. The outbreak was entirely nosocomial, and was largely attributable to infection management and policy failures, rather than biomedical factors.
L-ascorbate (L-ascorbic acid, vitamin C) clearly has an inhibitory effect on cancer cells. However, the mechanism underlying differential sensitivity of cancer cells from same tissue to L-ascorbate ...is yet to be clarified. Here, we demonstrate that L-ascorbate has a selective killing effect, which is influenced by sodium-dependent vitamin C transporter 2 (SVCT-2) in human breast cancer cells. Treatment of human breast cancer cells with L-ascorbate differentially induced cell death, dependent on the SVCT-2 protein level. Moreover, knockdown of endogenous SVCT-2 via RNA interference in breast cancer cells expressing high levels of the protein induced resistance to L-ascorbate treatment, whereas transfection with SVCT-2 expression plasmids led to enhanced L-ascorbate chemosensitivity. Surprisingly, tumor regression by L-ascorbate administration in mice bearing tumor cell xenograft also corresponded to the SVCT-2 protein level. Interestingly, SVCT-2 expression was absent or weak in normal tissues, but strongly detected in tumor samples obtained from breast cancer patients. In addition, enhanced chemosensitivity to L-ascorbate occurred as a result of caspase-independent autophagy, which was mediated by beclin-1 and LC3 II. In addition, treatment with N-acetyl-L-cysteine, a reactive oxygen species (ROS) scavenger, suppressed the induction of beclin-1 and LC3 II, implying that the differential SVCT-2 protein-dependent L-ascorbate uptake was attributable to intracellular ROS induced by L-ascorbate, subsequently leading to autophagy. These results suggest that functional SVCT-2 sensitizes breast cancer cells to autophagic damage by increasing the L-ascorbate concentration and intracellular ROS production and furthermore, SVCT-2 in breast cancer may act as an indicator for commencing L-ascorbate treatment.
The genetics behind the progression of myelodysplasia to secondary acute myeloid leukemia (sAML) is poorly understood. In this study, we profiled somatic mutations and their dynamics using next ...generation sequencing on serial samples from a total of 124 patients, consisting of a 31 patient discovery cohort and 93 patients from two validation cohorts. Whole-exome analysis on the discovery cohort revealed that 29 of 31 patients carry mutations related to at least one of eight commonly mutated pathways in AML. Mutations in genes related to DNA methylation and splicing machinery were found in T-cell samples, which expand at the initial diagnosis of the myelodysplasia, suggesting their importance as early disease events. On the other hand, somatic variants associated with signaling pathways arise or their allelic burdens expand significantly during progression. Our results indicate a strong association between mutations in activated signaling pathways and sAML progression. Overall, we demonstrate that distinct categories of genetic lesions play roles at different stages of sAML in a generally fixed order.
A gas pressure infiltration method was used to prepare diamond particles reinforced Cu-B alloy matrix composites (Cu-xB/diamond, x = 0.3 and 1.0 wt%). The Raman spectroscopy and X-ray diffraction ...(XRD) analysis confirm the formation of boron carbide (B4C) at the Cu/diamond interface. The amount of interfacial boron carbide increases with increasing boron content in the Cu matrix. A high thermal conductivity of 868 W/mK and corresponding coefficient of thermal expansion of 5.3 × 10−6/K are obtained in the Cu-0.3 wt%B/diamond composite. When the boron content increases to 1.0 wt% B, the thermal conductivity decreases to 647 W/mK. It is found that boron carbide plays a critical role in improving the interfacial bonding and enhancing the thermal conductivity of the Cu-B/diamond composites; however, too much interfacial boron carbide will deteriorate the thermal conductivity of the composites.
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•The Cu-B/diamond composites are prepared by gas pressure infiltration.•The amount of B4C formed at the interface is increased with increasing boron addition to the Cu matrix.•A high thermal conductivity of 868 W/mK is obtained in the Cu-0.3 wt%B/diamond composite.•A low CTE of 5.3 × 10−6/K at 313 K is obtained in the Cu-0.3 wt%B/diamond composite.
Weak interface bonding inhibits high thermal conductive potential of diamonds in metal matrix composites reinforced with diamond particles (Cu/diamond composites). With an attempt to modify the ...Cu/diamond interface, we combine Cr pre-coating and Cr alloying to produce Cu-Cr/Cr-diamond composites by gas pressure infiltration. High resolution transmission electron microscopy (HRTEM) results reveal that Cr pre-coating on the diamond surface before infiltration promotes the formation of highly active graphite-like structures. These structures enhance the interfacial reaction and intensify the formation of a uniform and dense carbide layer on the diamond surface. By altering the Cr concentration in the Cu-Cr alloy matrix, the thickness of interfacial carbide layer is tailored. As a result, a maximum thermal conductivity of 810 W m-1 K-1 is achieved in the Cu-0.5 wt%Cr/Cr-diamond composite, which is the highest value among Cr-modified Cu/diamond composites reported so far. The high thermal conductivity is attributed to optimal interface conditions: moderate thickness of interfacial carbide layer, uniform and dense carbide layer on the diamond surface, and crystallographically aligned interfacial graphite layers. This study offers a new route to modifying interface bonding and to enhancing thermal conductivity of Cu/diamond composites.
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•The Cu-Cr/Cr-diamond composites are prepared by gas pressure infiltration.•Highly active graphite-like structures promote the formation of interfacial carbide layer.•A high thermal conductivity of 810 W m-1 K-1 is achieved in the Cu-0.5 wt%Cr/Cr-diamond composite.
The art of addition and subtraction: By confining the nucleation and growth of Rh atoms only to the corners and edges of Pd cubic seeds, Pd‐Rh core–frame nanocrystals were obtained with concave side ...faces. The Pd cores were then selectively removed by oxidative etching to generate Rh cubic nanoframes with a highly open structure (see picture).
A long-standing question in the field of tumor immunotherapy is how Th2 cytokines block tumor growth. Their antitumor effects are particularly prominent when they are secreted continuously in tumors, ...suggesting that Th2 cytokines may create a tumor microenvironment unfavorable for tumor growth independently of adaptive immunity. In this study, we show that local production of IL-33 establishes a high number of type 2 innate lymphoid cells (ILC2s) with potent antitumor activity. IL-33 promotes secretion of a massive amount of CXCR2 ligands from ILC2s but creates a tumor microenvironment where tumor cells express CXCR2 through a dysfunctional angiogenesis/hypoxia/reactive oxygen species axis. These two signaling events converge to reinforce tumor cell-specific apoptosis through CXCR2. Our results identify a previously unrecognized antitumor therapeutic pathway wherein ILC2s play a central role.
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