Residual activity of cetrimide and chlorhexidine on Enterococcus faecalis-infected root canals

Effective final irrigation regimen is an important step in order to achieve better disinfection and ensure residual antimicrobial effects after root canal preparation. The aim of this study was to compare the residual antimicrobial activity of 0.2% cetrimide, and 0.2% and 2% chlorhexidine in root canals infected with Enterococcus faecalis. Biofilms of E. faecalis were grown on uniradicular roots for 4 weeks. After root canal preparation, root canals were irrigated with 17% ethylenediaminetetraacetic acid （EDTA） to remove the smear layer. The roots were randomly divided into three experimental groups （n=26） according to the final irrigating solution： Group I, 5 mL 0.2% cetrimide; Group II, 5 mL 0.2% chlorhexidine; and Group III, 5 mL 2% chlorhexidine. Samples were collected for 50 days to denote the presence of bacterial growth. The proportion of ungrown specimens over 50 days was evaluated using the nonparametric Kaplan-Meier survival analysis. Differences among groups were tested using the log-rank test and the level of statistical significance was set at P〈0.05. The highest survival value was found with 2% chlorhexidine, showing statistically significant differences from the other two groups. At 50 days, E. faecalisgrowth was detected in 69.23% specimens in Groups I and II, and in 34.61% specimens of Group III. There were no significant differences between 0.2% cetrimide and 0.2% chlorhexidine. Final irrigation with 2% chlorhexidine showed greater residual activity than 0.2% chlorhexidine and 0.2% cetrimide in root canals infected with E. faecalis.

Identical full-scale biogas-lift reactors(BLRs) with anaerobic granular sludge and residual activated sludge for brewery wastewater treatment and kinetic modeling

Two identical full-scale biogas-lift reactors treating brewery wastewater were inoculated with different types of sludge to compare their operational conditions, sludge characteristics, and kinetic models at a mesophilic temperature. One reactor （R1） started up with anaerobic granular sludge in 12 weeks and obtained a continuously average organic loading rate （OLR） of 7.4 kg chemical oxygen demand （COD）/（m3.day）, COD removal efficiency of 80%, and effluent COD of 450 mg/L. The other reactor （R2） started up with residual activated sludge in 30 weeks and granulation accomplished when the reactor reached an average OLR of 8.3 kg COD/（m^3·day）, COD removal efficiency of 90%, and effluent COD of 240 mg/L. Differences in sludge characteristics,biogas compositions, and biogas- lift processes may be accounted for the superior efficiency of the treatment performance of R2 over R1. Grau second-order and modified StoverKincannon models based on influent and effluent concentrations as well as hydraulic retention time were successfully used to develop kinetic parameters of the experimental data with high correlation coefficients （R2 〉 0.95）, which further showed that R2 had higher treatment performance than R1. These results demonstrated that residual activated sludge could be used effectively instead of anaerobic granular sludge despite the need for a longer time.

Effects of different drying methods on drying kinetics and physicochemical properties of Chrysanthemum morifolium Ramat

The effects of infrared-assisted hot-air drying(IR-HAD),temperature,humidity controlled hot-air drying(THC-HAD),and hot-air drying(HAD)on the drying kinetics,physicochemical properties,chlorogenic acid content and microstructure of chrysanthemum were experimentally examined.The results showed that the drying time reduced with increasing air drying temperature,with IR-HAD needing the shortest drying time,followed by THC-HAD and HAD.The effective moisture diffusivities(Deff)of chrysanthemum under IR-HAD,THC-HAD,and HAD at 60℃ were 3.22×10^(-9) m^(2)/s,2.19×10^(-9) m^(2)/s,and 2.89×10^(-9) m^(2)/s,respectively.IR-HAD preserved chrysanthemum surface color better than THC-HAD and HAD,whereas the THC-HAD samples obtained higher water holding capacity(WHC),water binding capacity(WBC),and chlorogenic acid content.Additionally,peroxidase(POD)residual activity of the samples decreased with increasing blanching time.The current work provides a theoretical basis for the drying of chrysanthemum.