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Amino group-functionalized magnetic particles have wide applications in enzyme immobilization, DNA extraction, drug delivery, water purification, catalysis, and sensor. In this paper, Fe3O4/PPy microspheres with a well-defined coreshell structure have been prepared through an interfacial polymerization approach without surfactant. The magnetic composite spheres were characterized with XRD, FTIR, SEM, TEM, and magnetometry techniques, and further tested as the adsorbent to isolate plasmid DNA from Escherichia coli (E. coli) DH5α cells. The magnetic separation yields high-quality plasmid DNA in satisfying productivity as compared to the conventional phenolchloroform extraction.

Incompatible numerical manifold method (INMM) uses interpolation functions based on the concept of partition of unity, and considers the asymptotic solution and the discontinuity of displacement. This paper describes the application of INMM to bi-material interfacial crack. The two dimensional near-tip asymptotic displacement functions are added to the trial function approximation. This enables the domain to be modeled by manifold elements without explicitly meshing the crack surfaces. The crack-tip enrichment functions are chosen as those that span the asymptotic displacement fields for an interfacial crack. The INMM facilitates the incorporation of the oscillatory nature of the singularity within a conforming manifold element approximation. The complex stress intensity factors for bi-material interfacial cracks are numerically evaluated. Good agreement between the numerical results and the analytical solutions for benchmark interfacial crack problems is realized.