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BACKGROUND: In enzyme immobilization, one crucial step is carrier selection; the immobilization efficiency is a major factor. It should be improved since enzyme is one of the expensive components in the procedure. Most carriers need to be activated before immobilization and the immobilized efficiency is low, especially using bacterial cellulose (BC). In this study, the immobilized efficiency of BC was improved by the special physical property, high water capacity.

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The main objective of this study is to enhance the heat and transfer process of absorptionusing the nanofluidsas the working medium. Carbon nanotubes-ammonia nanofluids (the binary nanofluids) are prepared. The thermal conductivity of the binary nanofluids and the bubble absorption process enhancement are examined experimentally. The results show the thermal conductivity of the carbon nanotubes-ammonia nanofluid is higher 16% than that of NH/HzO solution. And the carbon nanotubes-ammonia nanofluid has a great enhanced effect to the NH/HzO absorption.

The effect of binder and compression on the transport parameters of the multilayer gas diffusion layer (GDL) is numerically studied by the lattice Boltzmann method. A stochastic algorithm is implemented to generate three multilayer GDLs with a porosity gradient and a uniform GDL, and then, the GDLs are compressed after the binder is added to obtain structures with various binder volume fractions and various compression ratios. The pore size distribution, through-plane (TP) permeability, in-plane (IP) permeability, tortuosity, and electric conductivity of the four structures of GDLs are analyzed. The pore size distributions of GDLs move toward smaller pores due to compression, and the GDL with a larger porosity gradient has a larger maximum pore size. The TP permeability decreases with the increase of compression ratio and binder volume fraction, and the TP permeability of the four GDLs decreases similarly due to compression, but the TP permeability of the multilayer GDL with a larger porosity gradient drops more due to the binder. IP permeability is slightly affected by the compression. Similar to TP permeability, the IP permeability of the multilayer GDL with a large porosity gradient decreases more due to the binder. Multilayer GDL with a small porosity gradient has a smaller tortuosity, more superior pore connectivity, and thus more outstanding gas permeability. The electric conductivity increases with the increase in compression ratio and binder volume fraction.