No abstract

Response surface methodology (RSM) based on Box-Behnken design (BBD) was employed to investigate the effect of ultrasonic treatment on b-carotene production by Blakeslea trispora. The optimized strategy involved exposing three-day-old mycelial cultures to ultrasonic treatment at a fixed frequency of 20 kHz, power of 491 W, treatment time of 3 min, working time of 3 s, and rest time of 5:8 s, repeated four times at a 24-h interval. Mycelium growth was not significantly promoted under ultrasonic stimulation; however, the glucose metabolism increased by about 10%, the average size of the aggregates significantly decreased, and the uptake rate of imidazole into cells was increased about 2.5-fold. After a 6-d culture, the technique produced 173 mg=L of b-carotene and 82 mg=L of lycopene, which represented an increase of nearly 40:7% and 52:7%, respectively, over the yields obtained in cultures without ultrasonic treatment

No abstract

The effects of four hindered phenolic antioxidants in the short-term heat-oxygen stability of High-Density Polyethylene (HDPE) was evaluated by the Melt Flow Rate (MFR) and Oxidation Induction Time (OIT) analyses. The results showed that Irganox 1330 and Irganox 1010 had more excellent processing property and oxidation resistance behavior in HDPE than Irganox 1024 and Irganox 3114. The OIT values of HDPE with Irganox 1330 and Irganox 1010 were up to 97.25 min and 89.73 min respectively. The long-term accelerated heat-oxygen stability tests of HDPE containing hindered phenolic antioxidants were carried out at 110°C in deionized water pressurized with pure oxygen at a pressure of 10 MPa. The characterization of the long-term heat-oxygen stability was performed by Fourier Transform Infrared (FTIR), Differential Scanning Calorimetry (DSC) and tensile testing. However, the results exhibited that the aging resistance of HDPE containing Irganox 1010 was inferior to that of HDPE containing Irganox 1024 and Irganox 3114, which is quite contrary to their short-term effect on HDPE stabilization. It may be speculated that the ester groups of Irganox 1010 undergo hydrolysis during the long-term heat-oxygen stability tests, leading to the formation of 3-(3,5-ditert-butyl-4-hydroxy-phenyl) propanoic acid and pentaerythritol.

No abstract