Synchrotron small-angle X-ray scattering (SAXS) was used to investigate the microphase structure and microphase separation kinetics of two segmented polyurethanes with 4,4'-diphenylmethyl diisocyanate (MDI) and l,4'-butanediol (BD) as the hard segment and poly(tetramethylene oxide) (PTMO) and poly (propylene oxide) end-capped with poly (ethylene oxide) (PPO-PEO) (M" ~2000) as the soft segments. A more complete phase separation was observed in the PTMO based sample although PTMO and PPO-PEO have almost identical solubility parameters. This phase separation behavior could be explained as due partially to a kinetic factor. The microphase separation kinetics from quenching a sample in the melt state to lower annealing temperatures could be described by a relaxation process. A single-relaxation time process was observed for the PTMO based sample. By variation of the soft segment molecular weight from 1000 to 2000, the relaxation time was reduced from ~103 to 64 s. This behavior strongly supports our argument that in a segmented polyurethane, hard segment mobility, system viscosity, and hard segment interactions are the three controlling factors. In the PPO-PEO-based sample a double-relaxation time process was observed. One of the relaxation times was 54 s while the other secondary process was 1.48 X 103 s.

The lignite biodegradation procedure to produce water-soluble humic materials (WSHM) with a Penicillium stain was established by previous studies in our laboratory. This study researched the effects of WSHM on the growth of Bradyrhizobium liaoningense CCBAU05525 and its nodulation on soybean. Results showed that WSHM enhanced the cell density of CCBAU05525 in culture, and increased the nodule number, nodule fresh weight and nitrogenase activity of the inoculated soybean plants. Then the chemical compounds of WSHM were analyzed and flavonoid analogues were identified in WSHM through tetramethyl ammonium hydroxide (TMAH)-py-GC/MS analysis. Protein expression profiles and nod gene expression of CCBAU05525 in response to WSHM or genistein were compared to illustrate the working mechanism of WSHM. The differently expressed proteins in response to WSHM were involved in nitrogen and carbon metabolism, nucleic acid metabolism, signaling, energy production and some transmembrane transports. WSHM was found more effective than genistein in inducing the nod gene expression. These results demonstrated that WSHM stimulated cell metabolism and nutrient transport, which resulted in increased cell density of CCBAU05525 and prepared the bacteria for better bacteroid development. Furthermore, WSHM had similar but superior functions to flavone in inducing nod gene and nitrogen fixation related proteins expression in CCBAU05525.

Self-consistent field theory with a dynamic extension is exploited to investigate the kinetics of the lamellar formation of symmetric block copolymers under the direction of external fields. In particular, three types of directed self-assembly methods - a permanent field for chemo-epitaxy, a dynamic field for zone annealing and an integrated permanent/dynamic field - are examined. For the chemo-epitaxy involving sparsely prepatterned substrates or zone annealing, the block copolymers generally develop into polycrystalline nanostructures with multiple orientations due to the lack of strong driving forces for eliminating the long-lived imperfections in a limited time. As the integrated chemo-epitaxy and zone annealing method is applied to the block copolymer systems, single-crystalline nanostructures with precisely registered orientations are achieved in a short annealing time owing to the mutual acceleration of defect annihilations, which cannot be produced by the conventional techniques alone. Furthermore, the integrated method allows the rapid fabrication of well-ordered nanostructures on the extremely sparse prepatterned substrates. Our theoretical work may serve to rationalize the faster modern nanolithographic fabrication of smaller microelectronic components using lower-spatial-frequency templates.

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