The Structural Evolution of ß-to-α Phase Transition in the Annealing Process of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

In this study, the structural and property changes induced in the highly ordered structure of preoriented poly(3-hydroxybutyrate-co-3-hydroxyvalerate) PHBV films containing the ß-form during annealing were investigated. The transformation of the ß-form was investigated by means of in situ wide-angle X-ray diffraction (WAXD) using synchrotron X-rays. The comparison of PHBV films with the ß-form before and after annealing was performed using small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The evolution mechanism of ß-crystal transformation was elucidated. It was revealed that most of the highly oriented ß-form directly transforms into the highly oriented α-form, and there might be two kinds of transformations: (1) The ß-crystalline bundles may be transformed one by one rather than one part by one part during annealing before a certain annealing time. (2) The ß-crystalline bundles crack or the molecular chains of the ß-form are separated from the lateral side after annealing after a certain annealing time. A model to describe the microstructural evolution of the ordered structure during annealing was established based on the results obtained.

Characterization on the phase separation behavior of styrene-butadiene rubber/polyisoprene/organoclay ternary blends under oscillatory shear.

The present work investigated the influence of organoclay (organo-montmorillonite, OMMT) on the phase separation behavior and morphology evolution of solution polymerized styrene-butadiene rubber (SSBR)/low vinyl content polyisoprene (LPI) blends with rheological methodology. It was found that the incorporation of OMMT not only reduced the droplet size of the dispersion phase, slowed down the phase separation kinetics, also enlarged the processing miscibility window of the blends. The determination on the wetting parameters indicated that due to the oscillatory shear effect, the OMMT sheets might localize at the interface between the two phases and act as compatibilizer or rigid barrier to prevent domain coarsening, resulting in slow phase separation kinetics, small droplet size, and stable morphology. The analysis of rheological data by the Palierne model provided further confirmation that the addition of OMMT can decrease the interfacial tension and restrict the relaxation of melt droplets. Therefore, a vivid "sea-fish-net" model was proposed to describe the effect of OMMT on the phase separation behavior of SSBR/LPI blends, in which the OMMT sheets acted as the barrier (net) to slow down the domain coarsening/coalescence in phase separation process of SSBR/LPI blends.

Effect of the treatment by slightly acidic electrolyzed water on the accumulation of γ-aminobutyric acid in germinated brown millet.

The accumulation of γ-aminobutyric acid and the microbial decontamination are concerned increasingly in the production of sprouts. In this work, the effect of the treatment by slightly acidic electrolyzed water on the accumulation of γ-aminobutyric acid in the germinated brown millet was evaluated by high performance liquid chromatography during germination. The results showed that slightly acidic electrolyzed water with appropriate available chlorine (15 or 30 mg/L) could promote the accumulation of γ-aminobutyric acid by up to 21% (P < 0.05). However, the treatment with slightly acidic electrolyzed water could not enhance the sprouts growth of the germinated brown millet. The catalase and peroxidase activities of the germinated brown millet during germination were in agreement with the sprouts growth. Our results suggested that the accumulation of γ-aminobutyric acid was independent of the length of sprouts in germinated grains. Moreover, the treatment with slightly acidic electrolyzed water significantly reduced the microbial counts in the germinated millet (P < 0.05) and the treatment with high available chlorine concentration (15 and 30 mg/L) showed stronger anti-infection potential in the germinated brown millet than that of lower available chlorine concentration (5 mg/L). In conclusion, the treatment with slightly acidic electrolyzed water is an available approach to improve the accumulation of γ-aminobutyric acid and anti-infection potential in the germinated brown millet, and it can avoid too long millet sprouts.

A novel biocompatible double network hydrogel consisting of konjac glucomannan with high mechanical strength and ability to be freely shaped.

A novel physically linked double-network (DN) hydrogel based on natural polymer konjac glucomannan (KGM) and synthetic polymer polyacrylamide (PAAm) has been successfully developed. Polyvinyl alcohol (PVA) was used as a macro-crosslinker to prepare the PVA-KGM first network hydrogel by a cycle freezing and thawing method for the first time. Subsequent introduction of a secondary PAAm network resulted in super-tough DN hydrogels. The resulting PVA-KGM/PAAm DN hydrogels exhibited unique ability to be freely shaped, cell adhesion properties and excellent mechanical properties, which do not fracture upon loading up to 65 MPa and a strain above 0.98. The mechanical strength and microstructure of the DN hydrogels were investigated as functions of acrylamide (AAm) content and freezing and thawing times. A unique embedded micro-network structure was observed in the PVA-KGM/PAAm DN gels and accounted for the significant improvement in toughness. The fracture mechanism is discussed based on the yielding behaviour of these physically linked hydrogels.

[Sustainable rice pest management and its economic benefits].

With rice varieties Jiahua 1 (resistant to the white backed plant hopper Sogatella furcifera) and Shanyou 63 (susceptible) as test materials, this paper studied the effects of different insecticide treatments on the pest population and quality and yield of rice grain, and evaluated their actual economic benefits (AEB). The results indicated that in the control plot, the peak density of S. furcifera on Jiahua 1 was only 1/10 of that on Shanyou 63. Throughout the whole rice growth period, the S. furcifera population on Jiahua 1 kept below economic injury level, while Shanyou 63 suffered heavy infestation by S. furcifera. The spider density in the control plot was 3 -7 times higher than that in the plots treated with insecticide following farmers' practice. No application of insecticide decreased the grain yield of Jiahua 1 and Shanyou 63 by 11. 8% and 43.4% , respectively. Compared with the control, spraying with insecticide one time decreased the AEB of Jiahua 1 and Shanyou 63 by 0.9% - 2.6% and 2.6% - 4.7% , respectively. Without insecticide application, the AEB of Shanyou 63 decreased by 32.9% - 36.1% , while that of Jiahua 1 increased by 2.2% - 4.8%. The income of planting Jiahua 1 without insecticide application was 9403 yuan x hm(-2) , which was remarkably higher than that (8632 yuan hm (-2)) of Shanyou 63 protected by spraying insecticide 3 times. It was worthwhile to point out that insecticide treatment did not affect the processing of rice grain and its commercial and edible quality, but decreased its protein content of Jiahua 1 and Shanyou 63.