The deformation behavior and corresponding microstructure evolution of a Mg
97Zn
1Y
2 (at.%) alloy with a long period stacking ordered (LPSO) structure subjected to hot compression were investigated. ...The peak stress at 573
K was about 190
MPa, and no macroscopic fracture took place up to a strain of about 60%. The mechanisms responsible for the mechanical performance of the Mg
97Zn
1Y
2 (at.%) alloy are discussed based on microstructural investigations using various electron microscopy techniques. The high strength at elevated temperature could be attributed to synergetic strengthening refinement of the LPSO via kinking and a limited fraction of dynamical recrystallization. Microcracks nucleated at the interfaces in the sandwich structure composed of LPSO and nanometer thick Mg slices could weaken the alloy at late stages of deformation, but their propagation could be limited within the individual kink band where the microcracks nucleated, which could ensure the capability of the alloy to resist premature or catastrophic fracture. Furthermore, lack of deformation twins in Mg grains effectively reduced the potential nucleation sites for cracks, which should be another reason for the good ductility of the alloy. These findings may provide or evoke insights into methods for optimizing the mechanical properties of Mg alloys.
Solute atoms segregation to the interfaces, such as grain boundary or twin boundary, often plays a critical role in modulating the properties of a metallic alloy. Deformation induced segregation to ...the interfaces has been a subject of significant research, since this is one of the key issues to fully understand the deformation mechanism and microstructure evolution in service of engineering materials. By means of the high-resolution aberration-corrected scanning transmission electron microscopy (STEM), we report the investigations of segregations to symmetrical boundaries, kink boundary (KB) and twin boundary (TB), in the Mg-Zn-Y alloys containing long period stacking ordered (LPSO) phases subjected to a compression at room temperature. We found that Zn atoms preferentially segregate to the deformation-induced symmetrical KBs in the LPSO structures and sandwiched Mg layers, while only a small amount of Y atoms concentrate at KB in LPSO structure. These enriched atoms may be in a random distribution, form nanoscale clusters or in a periodic pattern. Furthermore, solute atoms would rather decorate the segment of coherent TBs than enrich the overlapped TBs. Based on the direct atomic observations, the segregation mechanisms to the featured microstructures are proposed.
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Photochemical smog, characterized by high concentrations of ozone (O3) and fine particles (PM2.5) in the atmosphere, has become one of the top environmental concerns in China. Volatile organic ...compounds (VOCs), one of the key precursors of O3 and secondary organic aerosol (SOA) (an important component of PM2.5), have a critical influence on atmospheric chemistry and subsequently affect regional and global climate. Thus, VOCs have been extensively studied in many cities and regions in China, especially in the North China Plain, the Yangtze River Delta and the Pearl River Delta regions where photochemical smog pollution has become increasingly worse over recent decades. This paper reviews the main studies conducted in China on the characteristics and sources of VOCs, their relationship with O3 and SOA, and their removal technology. This paper also provides an integrated literature review on the formulation and implementation of effective control strategies of VOCs and photochemical smog, as well as suggestions for future directions of VOCs study in China.
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•Characteristics and sources of VOCs in China are reviewed.•Relationship of VOCs with O3 and SOA in China are reviewed.•Integrated literature review on the control strategies of VOCs and photochemical smog is provided.•Future directions of VOC study in China are suggested.
The present work examines the mechanism of formation of thermal shock crack patterns in ceramics. An attempt has been made to bridge the gap between theoretical predictions and experimental data. A ...set of experiments on thin ceramic specimens yielded two-dimensional readings of thermal shock crack patterns with periodical and hierarchical characteristics that vary with the thermal shock temperature. Based on the minimum potential energy principle the finite element method was used for numerical simulations, in which the temperature dependence of the material properties was considered. To overcome the difficulty of a lack of accurate data on the convective heat transfer coefficient at high temperatures, a “semi-inverse method” was developed, which explores a new method for estimating a physical quantity that is difficult to measure using physical quantities, which are relatively easy to measure. The numerical and experimental data were compared and discussed. The obtained numerical results are in good agreement with the experimental data. Furthermore, the numerical simulations can conveniently reproduce the evolution of thermal shock cracks, which is difficult to observe experimentally. In addition, some interesting phenomena related to thermal shock crack pattern evolution were observed. The present theoretical–numerical–experimental study has led to a much improved understanding of the formation and evolution of thermal shock crack patterns in ceramics.
The cross section for the process e^{+}e^{-}→π^{+}π^{-}J/ψ is measured precisely at center-of-mass energies from 3.77 to 4.60 GeV using 9 fb^{-1} of data collected with the BESIII detector operating ...at the BEPCII storage ring. Two resonant structures are observed in a fit to the cross section. The first resonance has a mass of (4222.0±3.1±1.4) MeV/c^{2} and a width of (44.1±4.3±2.0) MeV, while the second one has a mass of (4320.0±10.4±7.0) MeV/c^{2} and a width of (101.4_{-19.7}^{+25.3}±10.2) MeV, where the first errors are statistical and second ones are systematic. The first resonance agrees with the Y(4260) resonance reported by previous experiments. The precision of its resonant parameters is improved significantly. The second resonance is observed in e^{+}e^{-}→π^{+}π^{-}J/ψ for the first time. The statistical significance of this resonance is estimated to be larger than 7.6σ. The mass and width of the second resonance agree with the Y(4360) resonance reported by the BABAR and Belle experiments within errors. Finally, the Y(4008) resonance previously observed by the Belle experiment is not confirmed in the description of the BESIII data.
LAPTM4B (lysosomal protein transmembrane 4 beta) is a newly identified cancer-associated gene. Both of its mRNA and the encoded LAPTM4B-35 protein are significantly upregulated with more than 70% ...frequency in a wide variety of cancers. The LAPTM4B-35 level in cancer is evidenced to be an independent prognostic factor and its upregulation promotes cell proliferation, migration and invasion, as well as tumorigenesis in nude mice. In contrary, knockdown of LAPTM4B-35 expression by RNA interference (RNAi) reverses all of the above malignant phenotypes. We herein reveal a new role of LAPTM4B-35 in promoting multidrug resistance of cancer cells. Upregulation of LAPTM4B-35 motivates multidrug resistance by enhancement of efflux from cancer cells of a variety of chemodrugs with variant structures and properties, including doxorubicin, paclitaxel and cisplatin through colocalization and interaction of LAPTM4B-35 with multidrug resistance (MDR) 1 (P-glycoprotein, P-gp), and also by activation of PI3K/AKT signaling pathway through interaction of PPRP motif contained in the N-terminus of LAPTM4B-35 with the p85α regulatory subunit of PI3K. The specific inhibitors of PI3K and knockdown of LAPTM4B-35 expression by RNAi eliminate the multidrug resistance effect motivated by upregulation of LAPTM4B-35. In conclusion, LAPTM4B-35 motivates multidrug resistance of cancer cells by promoting drug efflux through colocalization and interaction with P-gp, and anti-apoptosis by activating PI3K/AKT signaling. These findings provide a promising novel strategy for sensitizing chemical therapy of cancers and increasing the chemotherapeutic efficacy through knockdown LAPTM4B-35 expression by RNAi.
Purpose
To assess the efficacy and safety of drug-eluting beads transarterial chemoembolization (DEB-TACE) in liver cancer patients with different times of previous conventional transarterial ...chemoembolization (cTACE) treatments.
Methods
367 liver cancer patients about to receive DEB-TACE treatment were enrolled in this prospective cohort study. All patients were divided into no previous cTACE group (NPC group), 1–2 times previous cTACE group (PC group) and triple or above previous cTACE group (TPC group) according to the times of previous cTACE treatments.
Results
There was no difference in complete response (CR) (
P
= 0.671) and objective response rate (ORR) (
P
= 0.062) among three groups. Additionally, no difference in overall survival (OS) among groups (
P
= 0.899) was found. As to liver function, most liver function indexes were deteriorative at 1 week after DEB-TACE operation, but returned to baseline at 1–3 months after DEB-TACE operation in all three groups, while percentage of abnormal total bile acid (TBA) patients was higher in TPC group than NPC and PC groups at 1–3 month post-DEB-TACE (
P
= 0.018). As for safety profiles, the incidence of pain during DEB-TACE operation was lower in TPC group compared to NPC and PC groups (
P
= 0.005), while no difference of other adverse events was found during and 1 month post-DEB-TACE treatment among three groups.
Conclusion
DEB-TACE treatment was equally efficient and tolerated in liver cancer patients with different times of previous cTACE treatments.
The precipitates inside deformation twins may block the dislocation motion and consequently affect the mechanical property of materials. Herein, at the atomic level, we directly visualize that the ...basal dislocation slips shear the twinned stacking faults (TSFs) within the deformation twins in an Mg–Zn–Y alloy containing long-period stacking ordered (LPSO) structures. The TSFs, enriched with solute atoms, could be considered as precipitates inside deformation twins. They are sheared by a single step or multiple shearing steps on the basal plane. The microstructural fingerprints, i.e., the width of basal shearing steps, enable a quantitative assessment of the local and total plastic shear strain due to the basal dislocation within the deformation twins. The TSFs can block dislocation slip, while the dislocation shearing induces large lattice distortion and even solute atoms redistribution at local intersection. The TSFs-dislocation interaction is expected to lower the basal dislocation motion and resultantly modulate the mechanical properties of magnesium alloys. These results may offer a novel strategy for strengthening and toughening magnesium alloys via tailoring the shearable precipitates.
Microstructure and voids evolution of a selective laser melted (SLM) AlSi10Mg alloy during tension were systematically investigated. The SLM AlSi10Mg sample is featured with a multi-level ...heterogeneous microstructure that is composed of melt pools (MPs), columnar Al grains and sub-cells. According to the Si morphologies and thermal history, the MP could be divided into three regions, including the fine structure zone (FSZ), remelted zone (RMZ) and heat-affected zone (HAZ), respectively. The Si segregation phenomenon on sub-cells boundaries is observed and may attributed to the constitutional supercooling. The tensile deformation behaviors of the vertical sample (V-sample) vary from the horizontal sample (H-sample) for that heterogeneous microstructure arises strain localization in V-sample. In addition, the voids have no obvious effect on the uniform plastic deformation, while they may affect the non-uniform deformation during tension. The combined effects of strain localization and void contribute to the earlier break in V-samples than in H-samples.
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