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Net primary productivity (NPP) of grassland is a key link and important part of the ecosystem's carbon cycle. We estimated the changes of NPP in grasslands of the Loess Plateau with unchanged land use types during 2000-2015 and analyzed its responses to the variation of main climate factors (annual precipitation, annual heavy rainfall, annual effective rainfall days, annual average temperature, annual maximum temperature, annual minimum temperature) using piecewise linear regression and Pearson correlation analysis. The driving factors of grassland NPP were further analyzed by pixel-by-pixel with boosted regression tree analysis. The results showed that annual mean grassland NPP in the Loess Plateau showed an increasing trend during the study period, with 51.3% of the total grassland area showing a significant increasing trend. The average increase rate of annual mean NPP declined from 15.23 g C·m -2 ·a -1 in 2000-2004 to 3.58 g C·m -2 ·a -1 in 2004-2015. There was a significant positive correlation between grassland NPP and precipitation, but negative correlation with temperature factors. Annual precipitation was the dominant climatic factor affecting NPP of the whole study area with the highest relative importance. Annual maximum temperature was the dominant driving force of grassland NPP of central Loess Plateau, while annual minimum temperature mainly affected the growth of grassland in high-altitude area of the western Loess Plateau.

Objective: To understand the endemic situation of schistosomiasis in Tongling County of Anhui Province, so as to provide the evidence for summarizing the "Twelfth Five-Year Plan" and formulating the "Thirteenth Five-Year Plan"., Methods: The data of schistosomiasis control reports and other information about Oncomelania hupensis status and schistosomiasis situation of population and livestock were collected and analyzed statistically in Tongling County from 2009 to 2014., Results: From 2009 to 2014, the schistosome infection rate and blood positive rate of the population decreased significantly, and only one case of acute schistosome infection was found in 2009. The schistosome infection rate of livestock decreased significantly, and the decreasing rate was 91.10% from 2009 to 2010. From 2009 to 2014, the snail area and average density of living snails presented decreasing trends but the densities of living snails increased in 2011 and 2012. After 2011, no schistosome infected snails were found., Conclusions: The schistosome infection rate of population has been controlled at a low level in Tongling County, but the snail area is still large in the marshland and lake regions, and the density of living snails is relatively high in the inland. Therefore, the schistosomiasis control work, especially snail control, still should be strengthened.

Recently, considerable attention has been focused on chitosan oligosaccharides (COSs) due to their various biological activities. COSs can be prepared by enzymatic degradation of chitosan, which is the deacetylation product of chitin, one of the most abundant biopolymers in nature. In the current study, we recombinantly expressed a chitosanase and used it for COS preparation. A bacillus-derived GH8 family chitosanase with a 6xHis tag fused at its N-terminal was expressed in the Escherichia coli strain BL21(DE3) as a soluble and active form. Its expression level could be as high as 500 mg/L. Enzymatic activity could reach approximately 140,000 U/L under our assay conditions. The recombinant chitosanase could be purified essentially to homogeneity by immobilized metal-ion affinity chromatography. The enzyme could efficiently convert chitosan into monomer-free COS: 1g of enzyme could hydrolyze about 100 kg of chitosan. Our present work has provided a cheap chitosanase for large-scale COS production in industry.