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Bee pollen is collected by honeybees from the pollen of flowers, with the addition of the nectar and their own secretions to form grains. Approximately 70% of the substances in bee pollen have biological activities, such as antioxidant, liver protection, anti-inflammatory, antibacterial and anti-cancer. However, the outer wall of pollen spores has the characteristics of acid resistance, alkali resistance, and anti-microbial decomposition. Without breaking the wall of spores, phenolic compounds can only be released from the germination pores, and thus the digestibility of bee pollen is only 52%-59% in vivo, meaning that most of them cannot be digested by human. Therefore, the wall breaking of spores has become necessary to improve the bioavailability of bee pollen. In this study, taking six kinds of bee pollen as research objects, including lotus, jujube, camellia, rape, rose, and schisandra, a wall breaking method of enzymatic hydrolysis combined with high-shear technology was used to reveal the effect of wall breaking on the phenolic compounds and antioxidant activities of bee pollen. An attempt was made to explore the protective effect of bee pollen, with or without wall breaking, on the OH-mediated oxidative damage of plasmid DNA for bee-pollen functional foods. An investigation was also made to find the effects of cellulase enzymatic hydrolysis on the wall breaking rates of different kinds of bee pollen. Different kinds of bee pollen exhibited different degrees of tolerance to the cellulase. The wall breaking rate of bee pollen increased with the increase of cellulase concentration. After six kinds of bee pollen enzymatically hydrolyzed, the wall breaking rate was significantly improved with high shear at 10 000-15 000 r/min for 30 s. More than 90% of wall breaking rate was achieved with less cellulase in the combined methods. The release of phenolic compounds from rape bee pollen was the most significant after the wall was broken (P<0.05). The total flavonoid content increased by 6.4 times, and the total phenol content increased from 8.6 mg/g to 21.6 mg/g, as well as the total phenol content of camellia bee pollen was 15.7 mg/g, an increase of 11.3% after the wall was broken. The phenolic compounds in six kinds of bee pollen were analyzed using high-performance liquid chromatography method with diode array detection (HPLC-DAD). The results showed that the types and content of phenolic compounds in bee pollen increased after the wall was broken. The concentration of jujube bee pollen to scavenge 50% DPPH free radicals is reduced by about 95%, and rape bee pollen is reduced by about 92%, the Fe2+ complex ability of jujube bee pollen increased from 0.36 mg/g to 1.16 mg/g, increased by about 2.2 times. The Fe3+ reducing power in the six types of bee pollen increased after the walls were broken. The Fe3+ reducing power of rape bee pollen increased from 6.2 mg/g to 55.8 mg/g, increased 8 times. After walls breaking, the protective abilities against DNA oxidative damage increased by 60.5%, 12.4%, 287.7%, 82.5%, 442.7% and4.8% in the six kinds of bee pollen( lotus, jujube, camellia, rape, rose and schisandra), respectively, indicating that the wall breaking made phenolic compounds of bee pollen fully be released, which can effectively improve the protective ability of OH-induced pBR322 plasmid DNA oxidative damage. This findings can provide a theoretical basis and strategy for the development of bee-pollen functional foods. [ABSTRACT FROM AUTHOR]

Soil erosion and sediment transport in Losses Plateau region are crucial for sustainable development of the local region and downstream of Yellow river due to the harmful sedimentation in the plain area. This study was to investigate the sediment transport capacity and flow-sediment relationship in different topographical units of different scales in loess region to explore the countermeasures for solving the sediment-related environmental issues. The Peijiamao watershed in losses region was selected as prototype for observation, including the embedded whole slope runoff plot (0.25 hm2) and 3 hydrological stations that were first branch of Qiaogou (subwatershed of Qiaogou watershed), Qiaogou watershed (subwatershed of Peijiamao watershed), and Peijiamao watershed (3930 hm2) with increasing scales, acting as 4 different topographical units. The rainfall, runoff and sediment contents data at these sites were recorded and collected from 1986 to 2008. Results showed that during the observation period the runoff depth and the sediment transport modulus at the annual timescales of the slope scale were more than that of the watershed scale, probably due to the well-known gravitational erosion occurring on the steeper slopes at slope scale in this region. When the spatial scale was up to the watershed scale, at the annual timescale the runoff depth increased with the spatial scale, but the sediment transport modulus decreased with spatial scale. However, at the inter-event timescale the maximum value of the runoff depth and the sediment transport modulus may occur at the different topographical units influenced by the rainfall process, rainfall duration, rainfall spatial distribution, the antecedent soil moisture content and other factors. Totally, 67.74% of the runoff peaks occurred at whole slope runoff plot and 29.03% at entire Peijiamao watershed. However, 38.71% of sediment transport modulus occurred at whole slope runoff plot and 48.39% occurred at entire Peijiamao watershed. With the increasing in spatial scale, the sediment transport capacity decreased dramatically. The sediment concentration carried by unit flow power of the whole slope runoff plot, the first-branch of Qiaogou and the Qiaogou was 186, 77 and 58 times that of entire Peijiamao watershed, respectively. It was further confirmed that slope scale triggered tremendous intensity of soil erosion, and the probability of hyper-concentration flow decreased when spatial scale increased. The gentler slope in the larger watersheds from first branch of Qiaogou to the whole Peijiamao watershed and more interception by the flattened terraces might lower sediment transport capacity in this region. Furthermore, the probability of hyper-concentrated flow was closely related to the ratios of width to depth of the different gully. Result showed that the smaller the ratio of width to depth the bigger the probability of hyper-concentrated flow. In this study, the ratios of width to depth of the watershed gullies were 8.15, 15.86 and 38.09, respectively at the 3 watershed scales from first branch of Qiaogou to the whole Peijiamao watershed and the gully gradient decreased with spatial scales from 4.97% at subwatershed of Qiaogou watershed to 1.51% at Peijiamao wathershed. The runoff-sediment transport modulus relationship of different topographical units was in linear function, suggesting that runoff volume was the controlling factor of sediment transport. And with the increase in spatial scale, the runoff-sediment transport modulus relationship was more significant from 0.71 at whole slope runoff plot to 0.99 (for the decisive factor) at entire Peijiamao watershed scale. It also showed that curve slope decreased with increase in watershed area, with highest slope of 1.10×106 at whole slope runoff plot and 1210 at entire Peijiamao watershed indicating that the relationship between runoff and sediment was more complex in the slope scale. The results can provide valuble inforamtion for exploring the spatial scale effects and scale transformation of soil erosion in Losses Plateau region. [ABSTRACT FROM AUTHOR]