Keratin is widely recognized as a high-quality renewable protein resource for biomedical applications. A large amount of rabbit hair waste is produced in textile industries, because it has high medullary layer content, but poor spinnability. Therefore, it is of great significance to extract keratin from waste rabbit hair for recycling. In this research, an ultrasonic-assisted reducing agent-based extraction method was developed and applied to extract keratin from rabbit hair. The results showed that the ultrasonic treatment had a certain destructive effect on the structure of the fiber, and when combined with reducing agent, it could effectively promote the dissolution of rabbit hair, and extract keratin with high molecular weight between 31 and 94 kDa. The structure and properties of keratin were studied. Compared to the rabbit hair, the cystine content of keratin was significantly reduced, and the secondary structure changed from α-helix to β-sheet. The keratin products show excellent biocompatibility and antioxidant capacity. In addition, large keratin particles can be formed by assembly with a balance between intermolecular hydrophobic attraction as the concentration of urea in keratin solution decreased during dialysis.

Alloying is an effective method to refine coarse grains of an Al₁₃Fe₄ phase and strengthen Al-Fe alloys. However, the grain refinement mechanism remains unclear in terms of the thermodynamics. Herein, the influence of M-element, i.e., Cr, Mn, Co and Ni, addition on the activity of Al and Fe atoms, Gibbs free energy of the Al₁₃Fe₄ nucleus in Al-Fe melt and the formation enthalpy of an Al₁₃Fe₄ phase in Al-Fe alloys is systematically investigated using the extended Miedema model, Wilson equation, and first-principle calculations, respectively. The results reveal that the addition of different M elements increases the activity of Fe atoms and reduces the Gibbs free energy of the Al₁₃Fe₄ nucleus in Al-Fe melt, where the incorporation of Ni renders the most obvious effect, followed by Mn, Co, and Cr. Additionally, the formation enthalpy decreases in the following order: Al₇₈(Fe₂₃Cr) > Al₇₈(Fe₂₃Mn) > Al₁₃Fe₄ > Al₇₈(Fe₂₃Ni) > Al₇₈(Fe₂₃Co), where the formation enthalpy of Al₇₈(Fe₂₃Ni) is close to Al₇₈(Fe₂₃Co). Moreover, the presence of Ni promotes the nucleation of the Al₁₃Fe₄ phase in Al-Fe alloys, which reveals the mechanism of grain refinement from a thermodynamics viewpoint.

Sr-modification of A356 alloys has distinct shortages due to the volatilization and oxidation during remelting and pouring, which often reduce the modification efficiency and mechanical properties of the alloys. To avoid the adverse effects and enhance the comprehensive properties, the effects of heavy rare earth element holmium (Ho) modification on the microstructure and properties of the alloy were investigated. Ho addition inhibited the intrinsic orientation growth of (111)_Al planes and stimulated the growth of the (200)_Al planes for α-Al crystals. The addition of 0.2 wt.% Ho produced the best refinement effect for α-Al grains; 0.3 wt.% of Ho addition yielded the most distinct modification effect for eutectic Si phases, which was further improved by a T6 treatment. The extra addition of 0.4 wt.% Ho resulted in the complete loss of the refinement and modification effects and in the abnormal growth of the α-Al crystals. Ho additions produced Al₃Ho phases containing Fe elements, which were distributed on the boundaries of the α-Al dendrites. The corrosion-proof performance was enhanced by Ho addition and the T6 treatment; the tensile strength and elongation achieved the highest value upon 0.2 wt.% of Ho addition and the T6 treatment. Moreover, the hardness was also enhanced by Ho additions in both states.