[en] The non-isothermal crystallization kinetics and glass-forming ability of Ti₄₁Zr₂₅Be₂₈Fe₆ glassy alloy were investigated by differential scanning calorimetry. The activation energies corresponding to the characteristic temperatures have been calculated by Kissinger and Ozawa equations. Based on Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall models, it has been found that the local activation energy is higher at the beginning of the crystallization process for the first exothermic peak. The local Avrami exponent indicates that the first-step crystallization is mainly a high-dimensional nucleation and growth with an increasing nucleation rate. According to the calculated fragility index, Ti₄₁Zr₂₅Be₂₈Fe₆ alloy can be classified as ''strong glass former.'' The studied alloy also possesses a critical size up to centimeter order, and the high glass-forming ability is probably related to the relatively low Gibbs energy difference between the liquid and crystalline states. The critical cooling rate of Ti₄₁Zr₂₅Be₂₈Fe₆ glassy alloy has also been determined using Barandiaran-Colmenero's method. (orig.)

[en] The size-dependent microstructural evolution behavior has a significant impact on the thermoplastic flow behavior of metallic glass in the supercooled liquid region. In this work, double-cup extrusion tests, corresponding finite element method simulations and nanoindentation measurements of Zr₅₅Cu₃₀Al₁₀Ni₅ metallic glass samples with different sizes, are employed to study the relationship between the size-dependent free volume variations and thermoplastic flowability. Experimental results and theoretical analyses demonstrate that the free volume content increases with increasing sample size. The change tendencies of free volume content and micro-hardness are in a negative correlation. The variation regularity of extruded cup height ratio verifies that the thermoplastic flowability of Zr-based metallic glass is enhanced with rising sample size. Furthermore, the size-dependent free volume variations and distributions induced by internal microstructural evolution behaviors result in the evident variations of micromechanical properties. The results of this study will contribute to a more in-depth understanding of the size-dependent thermoplastic deformation behavior of Zr-based metallic glass.

[en] Here we propose a novel encapsulated vertical 3D RRAM structure with each resistive switching cell encapsulated by dielectric layers, contributing to both the reliability improvement of individual cells and thermal disturbance reduction of adjacent cells due to the effective suppression of unwanted oxygen vacancy diffusion. In contrast to the traditional vertical 3D RRAM, encapsulated bar-electrodes are adopted in the proposed structure substituting the previous plane-electrodes, thus encapsulated resistive switching cells can be naturally formed by simply oxidizing the tip of the metal bar-electrodes. In this work, TaO_x-based 3D RRAM devices with SiO_2 and Si_3N_4 as encapsulation layers are demonstrated, both showing significant advantages over traditional unencapsulated vertical 3D RRAM. Furthermore, it was found thermal conductivity and oxygen blocking ability are two key parameters of the encapsulation layer design influencing the scalability of vertical 3D RRAM. Experimental and simulation data show that oxygen blocking ability is more critical for encapsulation layers in the relatively large scale, while thermal conductivity becomes dominant as the stacking layers scale to the sub-10 nm regime. Finally, based on the notable impacts of the encapsulation layer on 3D RRAM scaling, an encapsulation material with both excellent oxygen blocking ability and high thermal conductivity such as AlN is suggested to be highly desirable to maximize the advantages of the proposed encapsulated structure. The findings in this work could pave the way for reliable ultrahigh-density storage applications in the big data era. (paper)

[en] In the design of hot forming processes for aluminum alloys, hot processing maps are usually used as a powerful tool for processing parameters optimizations. Although the stability of deformation is considered in conventional hot processing (CHP) maps, the difficulty of deformation, i.e., whether deformation is easy to occur, is not taken into account. Therefore, it is difficult for CHP maps to efficiently and accurately obtain the optimal processing parameters and achieve satisfying hot workability. Hence, in this study, thermal compression tests were performed to investigate the hot forming behavior of 5052 aluminum alloy in the deformation temperature range of 553-733 K and strain rate range of 0.001-1 s⁻¹. We proposed an activation energy-processing (AEP) map by coupling the CHP map and the activation energy value, and thereby applied it to evaluate the hot workability of 5052 aluminum alloy. In CHP maps, the region with the highest power dissipation efficiency is generally considered to be the best processing region. However, the AEP map shows that materials with satisfying hot workability not only depends on high power dissipation efficiency, but also on low activation energy values. At the strain of 0.7, the optimal hot processing region predicted by the CHP map lies in the temperature range of 583-673 K and strain rate range of 0.001-0.1 s⁻¹, but that predicted by AEP map locates in the temperature range of 643-733 K and strain rate range of 0.001-0.1 s⁻¹. Microstructure characterization implies that the optimal processing region predicted by the CHP map presents necklace-like structures, which are non-uniform and unbeneficial for deformation, while that predicted by the AEP map consists of fine, uniform and equiaxed grains. Thus, it is implied that the processing regions predicted by the AEP map are more suitable for forming, i.e., the reasonability of the AEP map is verified.

[en] Highlights: • A robust regularized extreme learning machine is proposed. • The robustness of the proposed algorithm is proved theoretically. • The proposed algorithm is applied to model a small-scale turbojet engine. • The precise power control for unmanned aerial vehicles is realized. In this paper, a robust extreme learning machine is proposed. In comparison with the original extreme learning machine and the regularized extreme learning machine, this robust algorithm minimizes both the mean and variance of modeling errors in the objective function to overcome the bias-variance dilemma. As a result, its generalization performance and robustness are enhanced, and these merits are further proved theoretically. In addition, this proposed algorithm can keep the same computational efficiency as the original extreme learning machine and the regularized extreme learning machine. Then, several benchmark data sets are used to test the effectiveness and soundness of the proposed algorithm. Finally, it is employed to model a real small-scale turbojet engine. This engine is fit well. Especially, on the idle phase, where the signal-to-noise ratio is low and it is very hard to model, the proposed algorithm performs well and its robustness is sufficiently showcased. All in all, the proposed algorithm provides a candidate technique for modeling real systems.

[en] Di-n-butyl phthalate (DBP) is one of the most dominant phthalate esters and is ubiquitous in the environment. Male reproductive toxicity of DBP and its active metabolite mono-butyl phthalate (MBP) has been demonstrated in in vivo and in vitro studies. The objective of this study was to explore the roles of RhoG-ELMO1-RAC1 in phagocytosis disrupted by MBP in TM4 cells. Mouse Sertoli cell lines (TM4 cells) were maintained and treated by various levels of MBP (1, 10, and 100 μM) for 24 h. Then, cells were harvested for further experiments. Phagocytic capacity of TM4 cells was detected by flow cytometry, immunofluorescence, and oil red O staining. RAC1 activity (GTP-RAC1) was measured by RAC1 pull-down assay. Expression of mRNA and protein related to phagocytosis including ELMO1, RhoG, and RAC1 was analyzed by qRT-PCR and Western blots, respectively. MBP inhibited phagocytosis of TM4 cells and downregulated GTP-RAC1 expression and movement to membrane markedly. Furthermore, ELMO1 protein expression was downregulated in a dose-dependent manner after MBP treatments. Additionally, expression of proteins relating to phagocytosis, including RhoG and GTP-RAC1, was decreased significantly, but expression of total-RAC1 remained unchanged. GTP-RAC1 expression increased dramatically after TM4 cells were transfected with ELMO1 or RhoG plasmid, but restored under co-treatments with MBP and ELMO1/RhoG plasmid. This study suggests that MBP can reduce the phagocytosis of Sertoli cells through RhoG-ELMO1-RAC1 pathway.

[en] The half-life of ${}^{95m}$Tc and the cross-sections of the ${}^{96}$Ru (n, x) ${}^{95m}$Tc reaction induced by D-T neutrons were measured through the neutron activation technique in combination with off-line γ-ray spectrometry. The neutron beam was generated from the T (d, n) ${}^4$He reaction using the K-400 neutron generator at the Chinese Academy of Engineering Physics (CAEP). Through exponential function fitting and a detailed discussion of the uncertainty evaluation, the measured half-life of ${}^{95m}$Tc was 61.88 ± 0.22 days, which uncertainty is reduced greatly compared with the currently recommended value. Based on the determination of the ${}^{95m}$Tc half-life, the cross-sections of ${}^{96}$Ru (n, x) ${}^{95m}$Tc reaction at the 13.85 ± 0.2, 14.30 ± 0.2 and 14.72 ± 0.2 MeV neutron energies were measured relative to the ${}^{93}$Nb (n, 2n) ${}^{92m}$Nb monitor reaction. Considering the correlations between different attributes, detailed uncertainty propagation was performed by the covariance analysis and the cross-sections were reported with their uncertainties and correlation matrix. Then, experimentally determined cross-sections were analyzed by comparing with the literature data available in the EXFOR database and theoretically calculated values using the TALYS-1.95 and EMPIRE-3.2.3 codes. The accuracy of current experimental results with the thorough uncertainties and covariance information is greatly improved, which is critical for verifying the reliability of the theoretical model and improving the quality of the nuclear database.

[en] Highlights: • Corrosion behaviors of CoCrFeMnNi high entropy alloys with different grain sizes were investigated. • Galvanic corrosion at grain boundaries will reduce the global corrosion resistance. • Continuous passive films cannot be formed on coarse-grained HEA. • Combination of reduced grain boundary density and continuous passive film can improve corrosion resistance. -- Abstract: This work investigated the corrosion behavior of the equiatomic CoCrFeMnNi high entropy alloy (HEA) in a 0.5 M H₂SO₄ solution. The grain size of the HEA was adjusted by annealing. The electrochemical analysis showed that the corrosion resistance of the CoCrFeMnNi HEA increases first and then decreases with the increase of grain size. When the grain size is lower than a certain value, increasing the grain size can improve the corrosion resistance. Fine-grained (≤1.24 μm) HEA forms abundant grain boundaries, which promotes the occurrence of galvanic corrosion at the grain boundaries with inter-grains, resulting in reduced corrosion resistance. However, coarse-grained (≥145.9 μm) HEA provides too few ionic diffusion channels to form a stable and continuous passive film, which also reduces the corrosion resistance. Nanoindentation and XPS tests showed that a high content of Fe (Ⅲ) oxides and Cr (Ⅲ) oxides are formed on the medium-grained HEA, which improves the chemical stability and mechanical strength of the passive films. Thus, the corrosion resistance of medium-grained HEA is much better than those of fine-grained and coarse-grained HEA.

[en] The poor thermoplastic formability is one of the bottlenecks in restricting the wide application of Ti-based bulk metallic glasses. In this study, alloying method was adopted to improve the thermoplastic formability of a lightweight Ti–Zr–Be bulk metallic glass (BMG). Different combinations of alloying elements, alloying routes and alloying contents have been tried to optimize the alloy composition. S parameter was found to be an effective indicator for evaluating the thermoplastic formability of the studied Ti-based bulk metallic glasses. A Ti₄₅Zr₂₀Be₃₀Fe₅ alloy, which possesses unique thermoplastic formability, has been successfully developed. A nanomoulding processing map for Ti₄₅Zr₂₀Be₃₀Fe₅ alloy has been constructed. To reduce the capillary effect, a wetting layer has been introduced during the nanomoulding process. Finally Ti-based BMG nanorods have been successfully fabricated in air, which further confirms the effectiveness of the proposed processing map and the superior thermoplastic formability of developed Ti₄₅Zr₂₀Be₃₀Fe₅ BMG.

[en] In this study, alloying method has been adopted to develop novel near-equiatomic high-entropy bulk metallic glasses (HE-BMGs) with high glass-forming ability (GFA). A class of quinary Zr₃₁Ti₂₇Be₂₆Cu₁₀M₆ (M = Ag, Al, Ni, V, Cr, and Fe) and senary Zr₂₈Ti₂₄Be₂₃Cu₉Ni₁₀N₆ (NV, Cr, Fe, Ag, and Al) alloys were designed. Based on the phase formation rules of high entropy alloys (HEAs), all the developed compositions fall into the zone in which bulk metallic glasses will form. Accordingly, fully glassy rod samples with diameters ranging from 6 to 15 mm have been successfully prepared by copper mould casting. The developed HE-BMGs also possess high specific strength and certain compressive plasticity. Compared with the senary alloys, the quinary alloys possess higher GFA, better plasticity but lower strength. Among these alloys, Zr₃₁Ti₂₇Be₂₆Cu₁₀Ni₆, Zr₃₁Ti₂₇Be₂₆Cu₁₀V₆ and Zr₃₁Ti₂₇Be₂₆Cu₁₀Ag₆ HE-BMGs have been chosen for further non-isothermal analyses according to their large glass forming ability. The apparent activation energies were calculated using Kissinger, Moynihan, Ozawa and Boswell methods. The local Avrami exponents and kinetic fragility were also studied. Based on the experimental results, we have discussed the high entropy effect on the GFA, mechanical properties and crystallization kinetics of developed HE-BMGs.