The demand for natural lactone gamma-decalactone (GDL) has increased in the fields of food and cosmetic products. However, low productivity during bioprocessing limits its industrial production. In this study, a novel composite porous cell carrier, bacterial cellulose-alginate (BC-ALG), was used for long-term biotransformation and production of GDL. The effects of this carrier on biotransformation and related mechanisms were investigated. BC-ALG carriers showed improved mechanical strength over ALG carriers, with their internal embedded cell pattern changed to an interconnected porous structure. In five repeated-batch biotransformation experiments, the maximum concentration of GDL obtained in culture with BC-ALG carriers was 8.37 g/L, approximately 3.7 times higher than that from the medium with an ALG carrier alone. The result indicated that multiple hydrogen bonding interactions at the interface between BC and ALG contributed to the compatibility and stability of BC-ALG carriers. On the basis of the above results, the BC-ALG composite carrier can be considered ideal for immobilisation of cells for the production of GDL on an industrial scale, and has the potential to be utilised in other biological processes.
Hyper Spectral Imager (HSI) is the first Chinese space-borne hyperspectral sensor aboard the HJ-1A satellite. We have developed a data preprocess flow for HSI images, which includes destriping, atmospheric correction and spectral filtering. In this paper, the product level of HSI image was introduced in the beginning, and a destriping method for HSI level 2 images was proposed. Then an atmospheric correction method based on radiative transfer mechanism was summarized to retrieve ground reflectance from HSI image. Furthermore, a new spectral filter method for ground reflectance spectra after atmospheric correction was proposed based on reference ground spectral database. Lastly, a HSI image acquired over Lake Dali in Inner Mongolia was used to evaluate the effect of the preprocess method. The HSI image after destriping was compared with the original HSI image, which shows that the stripe noise has been removed effectively. Both un-smoothed reflectance spectra and smoothed spectra using the preprocess method proposed in this paper are compared with the reflectance spectral derived with the well-known FLAASH method. The results show that the spectra become much smoother after the application of the spectral filtered algorithm. It was also found that the spectra using this new preprocessing method have similar results as that of the FLAASH method.
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