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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. [ABSTRACT FROM AUTHOR]

Poly(D,L-lactic acid)-co-poly(ethylene glycol) copolymer (D,L-PLEG) synthesized by melt polycondensation was irradiated using low energy electron beam (EB) in the presence of triallyl cyanurate (TAC) and tetraallyl pentaerythritol (TAPE) as crosslinking agents. The tensile strength of D,L-PLEG/TAC and D,L-PLEG/TAPE samples increases up to 48 MPa and 28 MPa at dose of 80 kGy and 60 kGy, respectively, and decreases with further increase of dose, whereas the elongation at break decreases continuously with increasing dose. The glass transition temperature (Tg) is improved to some extent due to the formation of molecular chain network. Degradation of D,L-PLEG is retarded with introduction of cross-linked network. The results suggest that the physical properties of crosslinked D,L-PLEG can be adjusted easily by varying irradiation dose. [ABSTRACT FROM AUTHOR]

PURPOSE: The purpose of this study was to determine the efficacy of reducing plaque and gingivitis when used as an adjunct to normal oral hygiene routine and regular professional care. METHODS: Eighty-two adult subjects were enrolled into a 6-month, double-blind, controlled parallel-designed clinical study. After being scaled and polished. they were randomized into two groups; essential oil-containing mouthrinse group and placebo mouth rinse group. Everyone rinsed twice a day for 6 months with 8mL mouthrinse. The subjects were provided with a soft nylon toothbrush and fluoride toothpaste and were asked not to use any other mouthrinse during die study. At baseline and at 3- and 6-month, subjects were evaluated for supragingival plaque and gingivitis. SPSS 13.0 software package was used for statistical analysis (student's t test). RESULTS: At 3- month, the essential oil-containing mouthrinse significantly produced a 9.02% inhibition of supragingival plaque development and a 11.88% inhibition of gingivitis development compared with the control group. At 6-month, the essential oil-containing mouthrinse significantly produced a 16.98% inhibition of supragingival plaque development and a 21.47% inhibition of gingivitis development compared with the control group. CONCLUSION: The essential oil-containing mouthrinse demonstrates a significant reduction in dental plaque, gingivitis and enhances overall gingival health compared with using placebo rinse. [ABSTRACT FROM AUTHOR]