A new on line titration method and device based on a new technique continuous flow titration is described. By the means of electronically controlled switching of a solenoid valve, the main component of the system, t...A new on line titration method and device based on a new technique continuous flow titration is described. By the means of electronically controlled switching of a solenoid valve, the main component of the system, the equivalent point of the titration is easily determined. Several kinds of mixing tools were examined, whereby a self made mixing chamber with minimum volume gave best results and was therefore used in the device. The error of the titration is within 0.2% and the relative standard deviation (RSD) is below 1.2%. The results show no difference compared with a commercial device, meanwhile the new on line titration system is cheaper and fully automated and thus easy to hand and less solvent consumption.展开更多
The development of surface acidity on rayon-based carbon fibers during mild electrochemical treatment was investigated. Conductimetric titration was the primary method used to investigate the functionalities on the ca...The development of surface acidity on rayon-based carbon fibers during mild electrochemical treatment was investigated. Conductimetric titration was the primary method used to investigate the functionalities on the carbon fiber surface. The acidity on the surface of the untreated carbon fiber was very low, while for the treated fibers, the acidity increased significantly.Moreover, with the treatment extent proceeded, the acidity on the fiber surface also increased. SEM analysis shows electrochemical treatment under intense treatment degree caused considerable etch on the fiber surface.Cavities and grooves can be observed on the surface via the SEM microphotograph. While in a more mild treatment, electrochemical treatment didn't cause great etch on the surface of the fiber.展开更多
The ability of heated scallop-shell powder (HSSP) to disinfect Escherichia coli ATCC 25922 biofilm was investigated. On account of its cryotolerance and cell surface characteristics, the E. coli strain is reportedly a...The ability of heated scallop-shell powder (HSSP) to disinfect Escherichia coli ATCC 25922 biofilm was investigated. On account of its cryotolerance and cell surface characteristics, the E. coli strain is reportedly a useful surrogate for E. coli O157: H7 in surface attachment studies. In this study, an E. coli ATCC 25922 biofilm was formed on a glass plate, and immersed in a slurry of HSSP. Following treatment, the disinfection ability of the HSSP toward the biofilm was non-destructively and quantitatively measured by conductimetric assay. The disinfection efficacy increased with HSSP concentration and treatment time. HSSP treatment (10 mg/mL, pH 12.5) for 20 min completely eliminated biofilm bioactivity (approximately 108 CFU/cm2 in non-treated biofilms). In contrast, treatment with NaOH solution at the same pH, and treatment with sodium hypochlorite (200 mg/mL) reduced the activity by approximately one to three log10. Fluorescence microscopy confirmed that no viable cells remained on the plate following HSSP treatment (10 mg/mL). Although alkaline and sodium hypochlorite treatments removed cells from the biofilm, under these treatments, many viable cells remained on the plate. To elucidate the mechanism of HSSP activity against E. coli ATCC 25922, the active oxygen generated from the HSSP slurry was examined by chemiluminescence analysis. The luminescence intensity increased with increasing concentration of HSSP slurry. The results suggested that, besides being alkaline, HSSP generates active oxygen species with sporicidal activity. Thus, HSSP treatment could also be effective for controlling biofilms of the toxic strain E. coli O157: H7, implicated in food poisoning.展开更多
文摘A new on line titration method and device based on a new technique continuous flow titration is described. By the means of electronically controlled switching of a solenoid valve, the main component of the system, the equivalent point of the titration is easily determined. Several kinds of mixing tools were examined, whereby a self made mixing chamber with minimum volume gave best results and was therefore used in the device. The error of the titration is within 0.2% and the relative standard deviation (RSD) is below 1.2%. The results show no difference compared with a commercial device, meanwhile the new on line titration system is cheaper and fully automated and thus easy to hand and less solvent consumption.
文摘The development of surface acidity on rayon-based carbon fibers during mild electrochemical treatment was investigated. Conductimetric titration was the primary method used to investigate the functionalities on the carbon fiber surface. The acidity on the surface of the untreated carbon fiber was very low, while for the treated fibers, the acidity increased significantly.Moreover, with the treatment extent proceeded, the acidity on the fiber surface also increased. SEM analysis shows electrochemical treatment under intense treatment degree caused considerable etch on the fiber surface.Cavities and grooves can be observed on the surface via the SEM microphotograph. While in a more mild treatment, electrochemical treatment didn't cause great etch on the surface of the fiber.
文摘The ability of heated scallop-shell powder (HSSP) to disinfect Escherichia coli ATCC 25922 biofilm was investigated. On account of its cryotolerance and cell surface characteristics, the E. coli strain is reportedly a useful surrogate for E. coli O157: H7 in surface attachment studies. In this study, an E. coli ATCC 25922 biofilm was formed on a glass plate, and immersed in a slurry of HSSP. Following treatment, the disinfection ability of the HSSP toward the biofilm was non-destructively and quantitatively measured by conductimetric assay. The disinfection efficacy increased with HSSP concentration and treatment time. HSSP treatment (10 mg/mL, pH 12.5) for 20 min completely eliminated biofilm bioactivity (approximately 108 CFU/cm2 in non-treated biofilms). In contrast, treatment with NaOH solution at the same pH, and treatment with sodium hypochlorite (200 mg/mL) reduced the activity by approximately one to three log10. Fluorescence microscopy confirmed that no viable cells remained on the plate following HSSP treatment (10 mg/mL). Although alkaline and sodium hypochlorite treatments removed cells from the biofilm, under these treatments, many viable cells remained on the plate. To elucidate the mechanism of HSSP activity against E. coli ATCC 25922, the active oxygen generated from the HSSP slurry was examined by chemiluminescence analysis. The luminescence intensity increased with increasing concentration of HSSP slurry. The results suggested that, besides being alkaline, HSSP generates active oxygen species with sporicidal activity. Thus, HSSP treatment could also be effective for controlling biofilms of the toxic strain E. coli O157: H7, implicated in food poisoning.
