This study aims to isolate the antimicrobial peptide (AMP) from buffalo casein hydrolyzed by Dregea sinensis Hemsl. protease. The AMP was isolated from hydrolysate by live bacteria adsorption, then analyzed using reversed-phase high-performance liquid chromatography, and the fraction with highest antimicrobial activity was identified by liquid chromatography-tandem MS. Further, we characterized the peptide in terms of its peptide sequence, structure, and antimicrobial activity. The results identified the AA sequence of the peptide as YLGYLEQLLRLK, which corresponds to residues 106 to 117 of bovine α S1-casein, and we named it BCp12. BCp12 displays α-helical structure, with high hydrophobic moments and net positive charge. BCp12 can inhibit the growth of indicator bacteria, with minimum inhibitory concentration values ranging from 0.8 to 1.6 mg/mL, and can induce low toxicity in mammalian cells. Antimicrobial activity of the BCp12 peptide remained stable under different salt concentrations but was sensitive to trypsin and high temperatures (121°C and above). The results support further research in the application of our newly generated AMP as an antimicrobial agent in the food industry and in food processing facilities.
In this paper, the geometrical design for the blade's surface in an impeller or for the profile of an aircraft, is modeled from the mathematical point of view by a boundary shape control problem for the Navier-Stokes equations. The objective function is the sum of a global dissipative function and the power of the fluid. The control variables are the geometry of the boundary and the state equations are the Navier-Stokes equations. The Euler-Lagrange equations of the optimal control problem are derived, which are an elliptic boundary value system of fourth order, coupled with the Navier-Stokes equations. The authors also prove the existence of the solution of the optimal control problem, the existence of the solution of the Navier-Stokes equations with mixed boundary conditions, the weak continuity of the solution of the Navier-Stokes equations with respect to the geometry shape of the blade's surface and the existence of solutions of the equations for the Gâteaux derivative of the solution of the Navier-Stokes equations with respect to the geometry of the boundary.
SUMMARYIn this paper, by using classical tensor calculus, we derive the compressible Navier-Stokes equation on a so-called stream surface which is a two-dimensional (2-D) manifold that gives a deÿnition of a stream function with the equation satisÿed by it. Based on this, a new algorithm is proposed which is called dimension split algorithm. This new method is di erent from the domain decomposition method. In the domain decomposition method, we have to solve a three-dimensional problem in each subdomain but we solve a 2-D problem in each subdomain. A numerical experiment for the turbomachine is provided.
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