In this study, the survival of Vibrio parahaemolyticus in suspension in the presence of tea-polyphenols for 6h was first examined. The shucked oysters containing V. parahaemolyticus then were exposed to 2048μg/mL , 1024 μg/mL and 512 μg/mL tea-polyphenols for 4h and the population ofV. parahaemolyticusin shucked oysters was determined every 1h. In addition, shucked oysters containingV. parahaemolyticusexposed into the dose of 1024 μg/mL tea-polyphenols were held at various temperature (0, 5, and 20°C) to examine survival ofV. parahaemolyticusevery 6h till 24h. Populations ofV. parahaemolyticusinoysterwere determined using 3-tube most probable number (MPN) method. The study found that the MIC of tea-polyphenols to Vibrio parahaemolyticus suspension is 1024 μg/mL; when exposed to 2048 μg/mL, 1024 μg/mLand 512μg/mL tea-polyphenols for 4h, the population ofV. parahaemolyticusinshucked oysters decreased by 3.29,2.43 and 1.84 Log10MPN/g respectively; 0, 5 and 20°C,1024μg/mL tea-polyphenols can decrease the population of V. parahaemolyticusinshucked by 4.10, 3.32 and 3.00LogMPN/g at 24thh. Sensory analysis showed that treatments of tea-polyphenols at concentrations 1024μg/mL did not cause negative effects on taste of oyster meat. These results indicated that tea-polyphenols have bactericidal effects againstV. parahaemolyticusand can be applied to shucked oysters to reduce contamination of V. parahaemolyticus.
Monitoring the hydrological activities of subglacial lakes is critical to understanding the subglacial hydrological system and evaluating the internal mass changes of the Antarctic ice sheet. Drainage or filling events of active lakes lead to elevation changes in the ice surface. These changes can be observed by satellite altimetry, but the monitoring must be conducted continuously since the water movements in active subglacial lakes may occur frequently. We used CryoSat-2 Baseline-D and ICESat-2 data from 2010 to 2020 to obtain the time series of the ice surface elevation changes for 17 active lakes. We also evaluated the uncertainty of the time series derived from the CryoSat-2 data by cross-validation. The mean and RMS of the biases between the CryoSat-2-based and ICESat-2-based time series are generally less than 0.3 m and 1.0 m, respectively. However, the mean and RMS are greater over the lakes with rough ice surfaces, such as Whillans6, KT1, Mac3, and Slessor23. The drainage and filling events continue exhibiting in the extended period and the hydrological activities of SLW, L12, Whillans6, L78, and Mac1 occurred periodically. Furthermore, we inferred the hydrological connections between the lakes combining simulated water pathways.
To investigate the hygienic quality of the lagoon seawater in Shanghai Jinshan City Beach (30°42 22 -30°43 06 N 121°20 40 -121°21 24 E) of North Hangzhou Bay, total coliform and fecal coliform was analyzed monthly from August 2006 to July 2007. The results showed that the densities of total coliform was no more than 1400MPN/L,the concentration is higher in July, August and September, the highest concentration of total coliform reached 1400MPN/L in September, after that, it began to decline. Monthly average fecal coliform was no more than 940MPN/L all the year round, likewise, it was relatively higher in July, August and September, but lower in winter and spring, with a lowest concentration of 20MPN/L,the highest concentration was 940MPN/L in September. From the regression analysis, it showed that coliform was positively correlated with fecal coli-group, their correlation coefficient was 0.7934. In addition, some environmental parameters including physical and chemical properties of seawater quality were also investigated. The environmental parameters were not positively correlated with both total coliform and fecal coliform. According to the Sea Water Quality Standard (GB3097-1997), the quality of seawater in Shanghai Jinshan City Beach was classified as the Second Grade and might be suitable for opening beach recreation park including swimming and other water direct contact activities.
A simple, rapid and accurate method for the determination of fluoride in Antarctic krill has been developed. The fluoride content in Antarctic krill was determined by ion chromatography. The method requires a simple sample clean-up procedure to remove the interfering Cl- from the hydrochloric acid extraction solution. The optimum extraction conditions of fluoride from Antarctic krill samples were obtained by adding 8mL of 1:11(v/v) hydrochloric acid solution and extracting for 60 min. Under these conditions, recoveries of fluoride from Euphausia superba and Penaeus vannamei were 97.9-105.6% and 95.1-101.9%, respectively. The limit of detection was 0.01mg/kg. The method was applied to the determination of fluoride in Antarctic krill. Key words: Fluoride, Antarctic krill, Ion chromatography
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