Dynamic computer-generated moiré profilometry based on high-density binary coding.

A dynamic computer-generated moiré profilometry based on high-density binary coding is proposed. For making full use of the maximum refresh rate and the maximum resolution of the digital light projector (DLP), the binary coded fringe is used to replace the conventional 256-gray-scale sinusoidal fringe, which can increase the refresh rate from the traditional 120 Hz to more than 1 kHz and meet the needs of dynamic measurement from the source. To realize the minimum equivalent wavelength and obtain the purest calculated moiré fringe, a minimum four-pixel period high-density binary fringe that satisfies the sampling theorem is designed for the DLP. The measuring accuracy of computer-generated moiré profilometry is effectively improved due to its minimum equivalent wavelength. The experimental results show the feasibility and practicability of the proposed method. It not only possesses higher measuring accuracy, but also possesses a proper potential application in dynamic three-dimensional measurement.

Biosynthesis of benzyl cinnamate using an efficient immobilized lipase entrapped in nano-molecular cages.

To improve the performance of lipase in biosynthesis of benzyl cinnamate, a new immobilized lipase by entrapping enzyme into nano-molecular cages was designed. Consequently, the entrapped lipase showed a robust immobilization, which diminished the leakage of lipase notably in use. Moreover, the entrapped lipase exhibited higher activity (57.1 U/mg) than free lipase (50.0 U/mg), demonstrating that the native conformation of lipase was not destroyed during immobilization. Compared with the adsorbed lipase (half-life 40.7 min) and free lipase (half-life 29.8 min), the entrapped lipase (half-life 85.3 min) increased the stability by about 2-3 times. Furthermore, the entrapped lipase was applied in biosynthesis of benzyl cinnamate, where it showed excellent activity and re-usability. After 7 cycles, the yield of benzyl cinnamate catalyzed by the entrapped lipase remained 70.2%, while the yield catalyzed by the adsorbed lipase was only about 10%. These results indicated that the nano-molecular cages could inhibit denaturation of lipase and maintain its activity well.

PEI-crosslinked lipase on the surface of magnetic microspheres and its characteristics.

Here, PEI@PMMA microspheres were prepared by grafting polyethyleneimine (PEI) on poly(methyl methacrylate) (PMMA) magnetic microspheres and successfully used to immobilize lipase. The results showed that PEI@PMMA microspheres had strongly adsorbed lipase (49.1 mg/g microsphere) via electrostatic attraction. To prevent lipase shedding, the adsorbed lipase was further crosslinked with PEI on microspheres using glutaraldehyde as crosslinker. Consequently, PEI-crosslinked lipase (2.14 U/mg) exhibited 2.6 times and 1.4 times higher activity respectively than the directly covalent lipase (0.82 U/mg) and the crosslinked lipase aggregates (1.57 U/mg), which was close to the activity of adsorbed lipase (2.20 U/mg). Conformational analysis from FTIR spectroscopy showed that PEI-crosslinked lipase retained its natural structure well. And the α-helix structure seemed to play a key role in enhancing lipase activity. Furthermore, the effects of various parameters on crosslinking reaction were investigated. Also, PEI-crosslinked lipase revealed higher pH and thermal stability. The Michaelis constant (Km) was increased and the optimum temperature of lipase was widened observably after crosslinking with PEI on PEI@PMMA magnetic microspheres.