Biofilm, which is tolerant to antibiotics treatment, was considered the key factor caused persistent infection which results in 99,000 deaths (Klevens, 2007) and 28-45 billion cost (Scott, 2009) per year in US. Also, marine fouling which is precipitated by biofilm on ship increases up to 40% fuel expenditure (Christie, 1987). And, numerous of corrosions of steels or coppers were caused by biofilm. Therefore, the inhibition of biofilm formation, in particular, the inhibition of the attachment of bacteria which is the first step of biofilm formation, was gained comprehensive attention. Chemicals, hydrophobicity, topography and material of surface were verified to relate to the inhibition of attachment. (Chu, 2002; Nurit, 2007; Kestin, 2009; Claudia, 2011). However, how the mechanical forces, such as stiffness of substrate, influence the bacterial attachment and biofilm formation are still not clear. Currently, I am working at the effect of substrate stiffness on biofilm.

In this study, we characterized the effects of synthetic brominated furanones, a group of QS inhibitors, on the persistence of P. aeruginosa and Escherichia coli. Our results revealed that (Z)-4-bromo-5-(bromomethylene)-3-methylfuran-2(5H)-one (BF8) can reduce persister formation in P. aeruginosa PAO1 and E. coli RP437 and restore the antibiotic susceptibility of isolated persister cells at growth non-inhibitory concentrations. In addition to planktonic persister cells, BF8 was also found to reduce persister formation in the biofilms of P. aeruginosa PAO1 and E. coli RP437.

Poly(L-lactic acid) (PLLA) is an important biobased and biodegradable polymer. PLLA has been commercially produced by Natureworks etc via ring opening polymerization of L-lactide in large scale and by Mitsui Toatsu via solution polymerization (SP) in pilot scale and has found many end-uses in biomaterials, fibers, disposable commodities, and package materials because of its good mechanical properties and excellent biodegradability and biocompatibility. However, new cost-effective manufacturing technologies are still very desired to reduce the production cost and to enhance the marketability of PLLA. Melt/solid-state polycondensation (MP/SSP) for PLLA synthesis was first reported by Kimura and coworkers. It appears to be an attractive and promising route for PLLA synthesis due to its cost effectiveness which results from direct use of aqueous LLA other than L-lactide. However, it has not yet been industrialized up to now even though many efforts have been taken in the last decade, mainly because its reaction rate is relatively low and thus very long reaction time is needed to reach high molecular weight. We are optimizing and trying to industrialize the process which includes four steps:

• Dehydration.

• Oligomerization.

• Melt polyconensation.

• Solid state polycondensation.

The kinetics of the tetrabutyl titanate-catalyzed homogeneous succinic acid/1,4-butylenediol (BDO) and heterogeneous terephthalic acid/BDO esterifications were investigated experimentally and theoretically. A unified kinetic model considering two main esterifications as well as one reversible polycondensation and two THF-forming side reactions has been developed for the two esterification systems. The model agrees well with the experimental results. The effects of reaction temperature, diol/diacid ratio, catalyst amount, and heterogeneity on the esterification kinetics are simulated and discussed.

The reversed phases was used very widely in the field of High Performance Liquid Chromatography (HPLC) as one of silica-based stationary phases. In the thesis, we brought the dendrimers into the preparation of silica-based stationary phases, used the first generations (G1) of carbosilane dendrimer as adhesive to bond the C12 to silica gel to get the C12 silica-based stationary phases with methods of gringnard reaction and hydrosilylation. Then the dendrimer-bond silica gel stationary phase was characterized by IR, TG and the test of hydrophobicity. Finally, the results show that the preparation preceeded successfully as designed, and the dendrimer-bond silica gel stationary phase has much better performance.