This study aims to develop a medical patch surface material featuring a microporous polyurethane (PU) membrane and to assess the material's properties and biological performance. The goal is to enhance the clinical applicability of pelvic floor repair patch materials.
The design of high-performance overhead aluminum wires is challenging, due to the intrinsic trade-off of strength-ductility and strength-electrical conductivity (EC). The in-situ halide salt reactions were used to introduce dual-size TiB2 particles into 6201 alloy to obtain out-bound mechanical properties with slight sacrifice of EC. With this strategy, the ultimate tensile strength, elongation after fracture and EC of the 4 wt%TiB2/6201Al composite are 360.9 MPa, 8.27% and 53.5% IACS, respectively, and these properties of the reference 6201 alloy are 325.0 MPa, 7.8% and 56.06% IACS. In the as-cast state, the majority of sub-micron TiB2 particles are segregated at the grain boundaries (termed as GBPs), forming a network pattern. The network is stretched along the rolling direction (RD) during deformation, and the orientation of GBPs is also rearranged from chaotic to a position with c axis nearly normal to the RD. In addition, semi-coherent particle/matrix interface is formed, which play a crucial role in strengthening the matrix. To optimize the EC, neutralization by adding Al–3B master alloy was performed, thus successfully eliminating the detrimental Al3Ti phase and precipitating excessive solute Ti atoms. The results show that not only the EC, but also the strength and ductility maximize at a composition around B:Ti = 2.0.
Herein, the evolution of long-period stacking ordered (LPSO) phases in the as-cast Mg-6Gd-1Zn-0.6Zr (wt.%) alloy are investigated via transmission electron microscopy (TEM) and atom probe tomography (APT). The TEM results reveal that two types of LPSO phase (a bulky interdendritic phase and a plate-like matrix LPSO phase) are formed in the as-cast sample. Most of the LPSO phases are confirmed to be of the 14H type, with a smaller proportion being of the 18R LPSO. Further, the APT results reveal that the composition of the interdendritic LPSO phase is closer to that of the ideal 14H phase compared to the matrix LPSO phase, and both the interdendritic and matrix LPSO phases exhibit a Gd/Zn ratio of 2.5, thereby indicating a deficient Zn content compared to the ideal 14H phase (i.e., 1.3). In addition, the influence of the LPSO phases on the deformation behavior is investigated at different compressive plastic strains using electron backscatter diffraction (EBSD) analysis to reveal twinning and slip behavior during deformation. The results indicate that the LPSO phase induces additional work hardening in the late stage of deformation via the suppression of {101¯1} compressive twinning and the activation of non-basal slip systems.
The ability of nanocarriers to enter tumor cells can be enhanced by positive surface charge. Nonetheless, the relationship between the spatial distributions of cationic groups and the endocytosis and tumor penetration of nanocarriers remains largely elusive. Here, using quaternary ammonium salt (QAS) as a model cationic group, a series of hybrid micelles (HMs) bearing QAS with different spatial distributions were prepared from star-shaped polymers with well-defined molecular architectures. The structural characteristics of HM, such as spatial location of QAS and local poly(ethylene glycol) (PEG) density near QAS, were investigated by both experimental techniques and dissipative particle dynamics (DPD) simulation. We show that the drug carriers with QAS extending to the micellar outer space allows QAS to facilitate cell surface binding with minimized hindrance, resulting in greatly enhanced endocytosis compared with nanocarriers with QAS attached onto the micellar surface or shielded by a PEG corona. This study offers cues for future development of tumor-penetrating drug delivery systems.
In order to reduce CO 2 emission and energy consumption, more recycled secondary materials have to be used in foundry industry, especially for Al-Si-Mg based alloys for semi-solid processing. In this paper, Al-Si-Mg based alloys with the addition of recycled secondary materials up to 30 % (10, 20, 30 %, respectively) have been produced by semi-solid processing. The solidification microstructure was investigated using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Furthermore, computed tomography (CT) was also used to elucidate the size, size distribution, number density, volume fraction of porosities. It was found that with the addition of the recycled secondary materials up to 30 %, there is no significant effect on the solidification microstructure in terms of the grain size and the shape factor of primary α-Al and the second α-Al. More importantly, the morphology of eutectic Si can be well modified and that of the Fe-containing phase (π-AlSiMgFe) can be tailored. Furthermore, with increasing recycled secondary materials, at least another two important issues should also be highlighted. Firstly, more TiB 2 particles were observed, which can be due to the addition of Al-Ti-B grain refiners for the grain refinement of recycled secondary materials. Secondly, a significant interaction between Sr and P was also observed in the recycled secondary materials. The present investigation clearly demonstrates that Al-Si-Mg based alloys with the addition of recycled secondary materials at least up to 30% can be used for semi-solid processing, which may facilitate better sustainability.
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