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Hot compression was performed on a multilayered Au−20Sn eutectic alloy to investigate the deformation behavior and microstructure evolution. During hot compression, microstructural spheroidization was initiated from plastic instability regions, and it was preferentially activated in vertical lamellae with a growth direction parallel to the compressive direction. Continuous dynamic recrystallization associated with lattice dislocations was the mechanism in both AuSn and Au5Sn multilayers. After spheroidization, strain accumulations were weakened in both of the equiaxed phases, and the deformation mechanism was substantially replaced by grain boundary sliding and migration. Based on these findings, hot rolling was conducted on an as-cast Au−20Sn alloy and a foil with a thickness of ~50 μm was successfully prepared. The present study can promote the development of Au−20Sn foils, and provide insights into the deformation behavior and microstructure evolution of multilayered eutectic alloys.

This study investigated whether listening comprehension played a mediator role between vocabulary and reading comprehension. 127 Mandarin-speaking children were longitudinally assessed at 6;4, 6;10...

Mature adipocytes are sensitive to stress and hypoxia, which are the two major obstacles in large-volume fat grafting. Bionic scaffolds are considered beneficial for fat grafting; however, their mechanism is still unclear. In this study, polycaprolactone scaffolds were fabricated by a 3D-printing technique and compounded with liposuction fat. They were implanted subcutaneously into nude mice. At different times, gross and histological observations were performed to evaluate the retention rates and histological morphologies. Adipocyte viability, apoptosis, and vascularization were analyzed by special immunostaining. Quantitative polymerase chain reaction was used to detect the variations in hypoxia and inflammation. The results showed that the volume and weight retentions in the scaffold group were higher than those in the fat group with the former exhibiting fewer vacuoles and less fibrosis. In immunostaining, elevated CD31+ capillaries, more perilipin+ adipocytes, and fewer TUNEL+ apoptotic cells were observed in the scaffold group by week 4. The lower expression of HIF-1α indicated the alleviation of hypoxia. In conclusion, the scaffold provided mechanical support to resist skin tension, thereby decreasing the interstitial pressure, and improving substance exchange and vascular ingrowth. In this regard, the scaffold attenuated hypoxia and promoted vascularization, making it a feasible method to increase long-term retention in fat grafting using scaffolds with suitable degradation rates and additional vascular maturation stimulation.

Background: Increasing evidence suggests that deubiquitinase USP7 participates in tumor progression by various mechanisms and serves as a potential therapeutic target. However, its functional role in melanoma remains elusive and needs to be investigated. Methods: The down-regulation of USP7 in A375 human melanoma cells was determined by high resolution liquid chromatography mass spectrometry (LC-MS/MS). The effects of USP7 expression on proliferation and apoptosis of melanoma cells were examined by western blot, Immunohistochemical and flow cytometry. Further study knock-down of USP7 in A375 cell lines, especially knockout USP7 using CRISPR-Cas9, verified USP7 regulate cell proliferation in vivo and in vitro .Western blot and qRT-PCR, Immunofluorescence were performed to investigate the mechanisms by which USP7 mediated melanoma growth through regulating the PI3K/Akt/FOXO pathways activity Results: Proteomic and western blotting analysis show that inhibition of USP7 increases expression of PRKAB1, CASP7, and PPP2R3A, attenuates expression of ATP6V0C and PEX11B. Furthermore, ATP6V0C and PEX11B are proposed to be the substrate for USP7 function. Conclusions: Our findings demonstrate that PI3K/Akt/FOXO and AMPK signaling pathways can be regulated by USP7 during melanoma progression and provide USP7 as an attractive anticancer target for melanoma.

The introduction of a scattering center to microdisk lasers has been considered as an effective way to tailor their far-field emissions. However, this approach is practically limited by its nearby modes with higher quality ($Q$) factors and worse directionalities. In this research, by applying the simple concept of parity-time ($\mathcal{P}\mathcal{T}$) symmetry, we demonstrate that the resonances with well-designed directionalities can be selectively excited in optical microcavities. Taking the annular microcavities as examples, the unidirectional laser emissions and single-mode operations have been realized simultaneously by breaking the $\mathcal{P}\mathcal{T}$ symmetry. More interestingly, we find that the $\mathcal{P}\mathcal{T}$-symmetric modulations on the imaginary parts of the refractive index in a circular microdisk can affect the internal ray dynamics and thus generate highly directional laser emission. This research can boost both the fundamental studies and the practical applications of $\mathcal{P}\mathcal{T}$-symmetric systems.

Au-20Sn eutectic alloys are an important lead-free solder applied in the welding temperature range from 280 to 350 °C. However, the poor formability originating from the brittle eutectic structure (AuSn + Au5Sn) restricts its applications because it is difficult to deform this alloy to the specifications required for industrial applications. In this study, the hot rolling process was carried out on an as-cast Au-20Sn alloy, and the deformation behaviour as well as the spheroidization evolution of the nanolayered structure was investigated in detail because the goal was to evaluate and optimize the thermoforming process of the Au-20Sn alloy. The results indicated that plastic instability occurred across the multilayers during hot rolling, which showed a gradual transition from geometric bending to the “S” type shear mode as the rolling strain increased. As a result, nanostructure spheroidization in a lamellar colony could take place preferentially based on these shear instability regions owing to a high strain accumulation in these places. Even so, the formation of high-angle grain boundaries in the AuSn lamellae occurred faster than that in the Au5Sn lamellae, resulting in a higher spheroidizing velocity in the AuSn phase. After spheroidization, a (0001)//transverse direction deformation texture formed in the AuSn phase, while a (0001)//normal direction deformation texture was introduced in the Au5Sn phase. Such differences in texture formation were primarily due to the different deformation mechanisms activated in these two phases due to their very different c/a ratios. This study can provide insights to improve the formability of Au-20Sn alloys during thermoforming.

Au–20Sn preforms such as microscale thin foils or wires can be widely used as lead-free solder in the high-power optoelectronics and hermetic sealing applications. However, as-cast Au–20Sn eutectic alloy with Au5Sn and AuSn phases is intrinsically brittle at room temperature due to limited slip systems associated with their complicated trigonal structure and hexagonal packed structure. In this study, we successfully made an Au–20Sn foil with thickness of 48 μm by multi-pass hot rolling on as-cast alloy with an initial thickness of 4 mm. The microstructure, texture and recrystallization evolutions of the Au–20Sn eutectic alloy during hot rolling process were investigated in detail. The results indicated that plastic instability occurs in the eutectic lamellar structure when the nanoscale layers were subjected to the rolling strain, and promoted the microstructural spheroidization. Besides, the spheroidizing behavior in AuSn phase was found more preferential compared with that in the Au5Sn phase. After dynamic recrystallization, ∥TD deformation texture was introduced in the AuSn phase while ∥ND deformation texture was formed in the Au5Sn phase. These phenomena were attributed to the difference in slip systems activated in the two phases associated with their different c/a ratios. A transition of dynamic recrystallization mechanism from the initial lamellar phase to the later equiaxed phase (in other words, from continuous dynamic recrystallization mechanism to discontinuous dynamic recrystallization) was observed, as evidenced by the evolutions of in-grain misorientation accumulation and grain boundary migration. Additionally, an interesting recrystallization phenomenon occurred that the AuSn grains could nucleate in the Au5Sn phase during hot rolling, which was considered as a strain induced phase decomposition behavior. The present studies can provide insight into understanding microstructural evolution of Au–20Sn eutectic alloy during hot rolling, which enables a further optimization of processing parameters to fabricate Au–20Sn alloy foils with desired microstructure and properties.