The degradation of plastics and the production of polyhydroxyalkanoates (PHA) / 生物工程学报

In recent years, the petroleum-based plastic pollution problem has been causing global attention. The idea of "degradation and up-cycling of plastics" was proposed for solving the environmental pollution caused by non-degradable plastics. Following this idea, plastics would be firstly degraded and then reconstructed. Polyhydroxyalkanoates (PHA) can be produced from the degraded plastic monomers as a choice to recycle among various plastics. PHA, a family of biopolyesters synthesized by many microbes, have attracted great interest in industrial, agricultural and medical sectors due to its biodegradability, biocompatibility, thermoplasticity and carbon neutrality. Moreover, the regulations on PHA monomer compositions, processing technology, and modification methods may further improve the material properties, making PHA a promising alternative to traditional plastics. Furthermore, the application of the "next-generation industrial biotechnology (NGIB)" utilizing extremophiles for PHA production is expected to enhance the PHA market competitiveness, promoting this environmentally friendly bio-based material to partially replace petroleum-based products, and achieve sustainable development with carbon-neutrality. This review summarizes the basic material properties, plastic upcycling via PHA biosynthesis, processing and modification methods of PHA, and biosynthesis of novel PHA.

THE PERMEABILITY OF BLOOD-BRAIN BARRIER AND PLACENTA TO SELENIUM IN RAT / 营养学报

15 rat dams were divided into 2 groups: selenium treated group drank water containing 2 ppm selenium during pregnancy and breast-feeding period, control group drank tap water. The concentration of selenium in brain tissue for dams were 0.73 ?0.11 (Se-treated) and 0.54 ?0.09 ug/g wet tissue (control), for neonates 0.32?0.02 (Se-treated) and 0.25 ? 0.03 (control), and for 20 days old pups 0.53?0.04 (Se-treated) and 0.44?0.06 (control). The results showed that the selenium administered orally could be transfered through placenta or blood-brain barrier of fetus, young pup and adult rat.