No abstract

Glucoamylase was immobilized onto novel porous polymer supports. The properties of immobilized glucoamylase and the relationship between the activity of immobilized enzyme and the properties of porous polymer supports were investigated. Compared with the native enzyme, the temperature profile of immobilized glucoamylase was widened, and the optimum pH was also changed. The optimum substrate concentration of immobilized glucoamylase was higher than that of native enzyme. After storage for 23 d, the immobilized glucoamylase still maintained about 84% of its initial activity, whereas the native enzyme only maintained about 58% of the initial activity. Moreover, after using repeatedly seven times, the immobilized enzyme maintained about 85% of its initial activity. Furthermore, the properties of porous polymer supports had an effect on the activity of the immobilized glucoamylase.

In this paper, BN interfacial phase was prepared on SiC fiber surface and CVD SiC gradient coating was prepared on the surface of SiCf/SiC-CMCs composite. CVD SiC coatings were fabricated by the pyrolysis of methyltrichlorosilane (MTS) in hydrogen at a low pressure of 5-10kPa. The ratio of MTS to hydrogen is 1 to 12.Oxidation behaviour is examined by placing the material with coats in air. The oxidizing temperatures were varied from 100°C to 1200°C. Optical microscope and SEM were used to observe the surface morphology and microstructure of coatings. XRD was used to characterize the phase composition. The results indicated that the Oxidation of SiC/SiC-CMC is the most serious at 800°C. Tensile strength test shows that the fracture strength of the material is the lowest and with the increase of temperature to 1200°C, the tensile strength of the material increases. Tensile strength test shows that the fracture strength of the material is the lowest and with the increase of temperature to 1200°C, the tensile strength of the material increases.