A novel bioflocculant HBF-3 produced by deepsea bacterium mutant Halomonas sp. V3a' was investigated with regard to its flocculating characteristics and mechanism. 4.0 m g l -1 HBF-3 showed the maximum flocculating activity of 96.9% in 5.0 g l -1 Kaolin suspension containing 11.25 mM CaCl 2 , and that its flocculating activity was more than 90% within 5-40°C and over 80% in a wide pH range (3.0-11.0). Chemical analyses indicated that the biopolymer HBF-3 was mainly a polysaccharide, including neutral sugar residues (20.6%), uronic acid residues (7.6%), amino sugar residues (1.6%) and sulfate groups (5.3%). Fourier transform infrared (FTIR) spectrum showed the presence of carboxyl and hydroxyl groups in HBF-3 molecular. The average molecular mass of HBF-3, as determined by gel filtration chromatography (GFC), was approximately 590 kDa. Flocculation of Kaolin suspension with HBF-3 acted as a model to explore the flocculating mechanism in which bridging mediated by Ca 2? was proposed as the primary action based upon the experimental observations.

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Optimal potassium (K) fertilization is beneficial for oilseed-rape (Brassica napus L.) yield and quality. However, the discrepancy between the high K demand of winter oilseed rape and low soil fertility and insufficient potassium input has limited the sustainable development of oilseedrape production. A series of on-farm experiments in the key winter oilseed-rape domains of China was conducted from 2004 to 2010 to evaluate K-fertilizer management for winter oilseed rape. Currently, the average NH 4 OAc-extractable K content in the 0-20 cm soil layer is 89.1 mg kg -1 indicative of "slight deficiency". In addition, farmers in China usually fail to use sufficient K fertilizer in oilseed-rape production, the average mineral-potassium-fertilizer input in 2010 being only 35 kg K ha -1 , far lower than the recommended rate of potassium for winter oilseed rape. Adequate potassium fertilization significantly raises seed yield. The average yieldincrease rate for the major production regions due to K-fertilizer application was 18.5%, and the average K fertilizer-use efficiency 36.1%. Based on the negative correlation between yield response to potassium fertilization and available soil K content, a soil-K-test index was established for winter oilseed rape with a threshold value for NH 4 OAc-extractable soil K of 135 mg kg -1 . When available soil K-content is below this threshold value, more K fertilizer should be applied to achieve high seed yield and to increase soil fertility. The major challenge for K-fertilizer management in winter oilseed-rape production in China will be to guide farmers in the different regions in making reasonable use of K fertilizer through soil K-testing technology in order to maintain both seed yield and soil fertility.

There are some real-world problems in which multiple objectives conflict with each other and the objectives change with time. These problems require an optimization algorithm to track the moving Pareto front or Pareto set over time. In this paper, we propose a predictive strategy based on special points (SPPS) which consists of three mechanisms. The first one is that the non-dominated set is predicted directly by feed-forward center points, which can eliminate many useless individuals predicted by traditional prediction using feed-forward center points. The second one is that a special point set(such as boundary point, knee point, etc.) is introduced into the predicted population which can track Pareto front or Pareto set more accurately. The third one is the adaptive diversity maintenance mechanism based on boundary points and center points. The mechanism can introduce diverse individuals of the corresponding number according to the degree of difficulty of the problem to keep the diversity of the population. The number of these diverse individuals is strongly related to the center points. Then, they are generated evenly throughout the decision space between the boundary points. The proposed strategy is