Utilizing the Adsorbability of Pseudoboehmite for Tailoring the Stability of an Aluminum Sulfate Alkali-free Accelerator for Shotcrete.

Shotcrete is widely used in tunnels, bridges, culverts, and other large-scale projects. The accelerator is an additive employed to expedite the setting time of shotcrete. Previous research primarily concentrated on enhancing the early strength of accelerators, whereas their long-term stability has been inadequately investigated. In this study, pseudoboehmite (PB) and amorphous aluminum hydroxide (AAH) were incorporated into the accelerator to enhance its stability over a period of 90 days without any signs of crystallization or delamination. Furthermore, the accelerator exhibited an initial setting time of 170 s, a final setting time of 550 s, and a compressive strength of 11.58 MPa after 1 day. The mechanism of effects was studied by isothermal calorimetry, FTIR, XRD, TG-DTG, and SEM analysis. The enhancement in stability is attributed to the distinctive adsorption and thixotropic properties of PB, which facilitate the formation of an electrical double-layer structure in acidic solutions. The expedited setting and hardening are primarily due to the equilibrium between Al3+, SO42-, and Ca2+ ions, which accelerates the hydration process of cement. This research offers a methodology for developing a high-performance, alkali-free liquid accelerator.

Characterization, mechanisms, structure-activity relationships, and antihypertensive effects of ACE inhibitory peptides: rapid screening from sufu hydrolysate.

This study investigates the characterization, mechanisms of action, structure-activity relationships, and in vivo antihypertensive effects of ACE inhibitory peptides derived from sufu hydrolysate following simulated gastrointestinal digestion. Sufu was enzymatically digested using pepsin, trypsin, and chymotrypsin to mimic gastrointestinal conditions, followed by ultrafiltration to fractionate the peptides based on molecular weight. The fraction under 1 kDa exhibited the highest ACE inhibitory activity. LC-MS/MS analysis identified 119 peptide fragments, with bioinformatics screening highlighting 41 peptides with potential ACE inhibitory properties. Among these, two peptides, AWR and LLR, were selected and synthesized for in vitro validation, displaying IC50 values of 98.04 ± 2.56 µM and 94.01 ± 5.07 µM, respectively. Stability tests showed that both peptides maintained their ACE inhibitory activity across various temperatures and pH levels. Molecular docking and Highest Occupied Molecular Orbital analysis indicated strong binding interactions between these peptides and ACE, with the second-position tryptophan in AWR and the N-terminal leucine in LLR identified as key bioactive sites. These findings were further supported by molecular dynamics simulations, which confirmed the stability of the peptide-ACE complexes. In vivo studies using spontaneously hypertensive rats demonstrated significant reductions in both systolic and diastolic blood pressure, indicating that AWR and LLR have strong antihypertensive potential. This study illustrates that ultrafiltration, combined with LC-MS/MS and bioinformatics analysis, is an effective approach for the rapid screening of ACE inhibitory peptides. These results not only enhance our understanding of sufu-derived peptides but also offer promising implications for hypertension management.