Cyclic brush (cb) copolymers that are composed of a cyclic core densely grafted with radiating polymer brushes have emerged recently as innovative materials for both fundamental and practical investigations due to their capability to form unimolecular micelles with greater stability relative to the analogues self-assembled by the bottlebrush (bb) copolymers with an identical molecular weight (MW). However, compared to the extensive and intensive studies on cb copolymers with homogeneous polymer brushes, the preparation and application of cb copolymers with heterogeneous polymer grafts remains unexplored likely due to the synthetic challenge. For this purpose, we reported in this study the first preparation of cb copolymers with heterogeneous polymer brushes using a diblock copolymer-based cyclic core template. An amphiphilic cb copolymer with both hydrophilic oligo (ethylene glycol) (OEG) and hydrophobic oligo (ε-caprolactone) (OCL) brushes grafting from a cyclic core was designed and synthesized by a combination of atom transfer radical polymerization (ATRP), intrachain click cyclization, and ring-opening polymerization (ROP) techniques. Interestingly, the resulting amphiphilic cb copolymers showed greater in vitro cytotoxicity relative to the bb analogues for anticancer drug delivery. The amphiphilic cb copolymers with heteropolymer grafts developed herein thus represent a novel platform for controlled drug release.
Purpose
High-temperature Daqu is a traditional fermentation starter that is used for Chinese Maotai-flavor Baijiu production. Although the bacteria in high-temperature Daqu are known to be responsible for developing the quality and flavor of Baijiu during the fermentation process, there is little information on the properties of the bacteria during the fermentation of high-temperature Daqu, especially machine-made high-temperature Daqu. This has limited the development of the Maotai-flavor Baijiu industry, particularly with regard to the mechanized production of Maotai-flavor Baijiu.
Methods
Illumina MiSeq high-throughput sequencing was applied to study bacterial compositions during the fermentation of handmade and machine-made high temperatures.
Results
The results show that bacterial diversity in machine-made Daqu was similar but higher than that in handmade Daqu at the end of fermentation, and there was no significant difference between the methods with regard to the dominant genera and their dynamic changes during fermentation. Rhizobium, Bacillus, Thermoactinomyces, Weissella, Lactobacillus, and Saccharopolyspora were the dominant genera during the fermentation of both Daqus, although the relative abundance of these dominant genera differed between the two methods. Interestingly, the machine-made Daqu contained a higher relative abundance of Bacillus than handmade Daqu at all fermentation times. Bacillus is the most important functional bacteria in the fermentation of Maotai-flavor Baijiu, suggesting that mechanical-molding methods could be applied to industrial Maotai-flavor Daqu production.
Conclusion
These results suggest that mechanical-molding methods could be applied to industrial Maotai-flavor Daqu production, which could be helpful for industrial Maotai-flavor Baijiu production and the development of fermentation technology.
A novel two-dimensional (2-D) periodic structure on the ablated hole wall is formed by using the method of single-beam femtosecond laser pulses irradiating a titanium target. This 2-D structure on the ablated surface, after consecutive irradiation of 10000 pulses, presents different spatial periods which characters a 1500 nm period along the hole wall in the vertical direction and a 400 nm period in the azimuthal direction of the hole. The reported experimental results can be well interpreted by a prophetic theoretical model of Bonch-Bruevich (A. M. Bonch-Bruevich et al., Opt. Eng. 31, 718 (1992)).
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