Experimental and in silico studies on three hydrophobic charge-induction adsorbents for porcine immunoglobulin purification

Three hydrophobic charge-induction adsorbents with functional ligands of 4-mercapto-ethyl-pyridine, 2-mercapto-methyl-imidazole or 2-mercapto-benzimidazole were evaluated in the purification of porcine immunoglobulin from porcine blood. Adsorption isotherms were studied under different pH conditions. The adsorbent with 2-mercapto-methyl-imidazole as the ligand showed reasonable adsorption capacity(43.60 mg·g^(-1)gel)with great selectivity and it also showed the best elution performance in chromatographic studies. A multi-pH step elution process was proposed for the 2-mercapto-methyl-imidazole adsorbent, and the results showed that high immunoglobulin purity(94.3%) and a yield of 9.8 mg·(ml plasma)^(-1) could be achieved under the optimal condition of loading(pH 5.0)–pre-elution(pH 7.0)–elution(pH 3.8). Moreover, molecular simulation was employed to help in analyzing the binding mechanism between the ligands and immunoglobulin, and the results showed that both 2-mercapto-benzimidazole and 2-mercapto-methyl-imidazole ligands were docked on the same pocket(around TYR319 and LEU309) of the Fc fragment of immunoglobulin, with 2-mercaptobenzimidazole showing stronger binding interactions.

Numerical investigation of air-entrainment in skimming flow over stepped spillways

As a widely used flood energy dissipator, the stepped spillway can significantly dissipate the kinetic or hydraulic energy due to the air-entrainment in skimming flow over the steps. The free-surface aeration involves the sharp deformation of the free surface and the complex turbulent shear flows. In this study, the volume of fluid （VOF）, mixture, and Eulerian methods are utilized to simulate the air-entrainment by coupling with the Reynolds-averaged Navier-Stokes/large eddy simulation （RANS/LES） turbulence models. The free surface deformation, air volume fraction, pressure, and velocity are compared for the three different numerical methods. Only the Eulerian＋RANS method fails to capture the free-surface aeration. The air volume fraction predicted by the VOF＋LES method best matches the experimental measurement, while the mixture＋LES method predicts the inception point of the air entrainment more accurately.