Hunt Pruitt (nailowner4)

Pure culture studies have shown that biofilm dispersal can be triggered if the nutrient supply is discontinued by stopping the flow. Stimulating biofilm dispersal in this manner would provide a sustainable manner to control unwanted biofilm growth in industrial settings, for instance on synthetic membranes used to purify water. The response of multispecies biofilms to nutrient limitation has not been thoroughly studied. To assess biomass dispersal during nutrient limitation it is common practise to flush the biofilm after a stop-period. Hence, flow-stop-induced biomass removal could occur as a response to nutrient limitation followed by mechanical removal due to biofilm flushing (e.g. biofilm detachment). Here, we investigated the feasibility to reduce membrane biofouling by stopping the flow and flushing the membrane. Using a membrane fouling simulator, biomass removal from synthetic membranes after different stop-periods was determined, as well as biomass removal at different cross flow velocities. Biomass removal from membrane surfaces depended on the nutrient limiting period and on the flow velocity during the biofilm flush. When flushed at a low flow velocity (0.1 m.s-1), the duration of the stop-period had a large effect on the biomass removal rate, but when the flow velocity was increased to 0.2 m.s-1, the length of the stop period became less considerable. The flow velocity during membrane flushing has an effect on the bacterial community that colonized the membranes afterwards. Repetition of the stop-period and biofilm flushing after three repetitive biofouling cycles led to a stable bacterial community. The increase in bacterial community stability coincided with a decrease in cleaning effectivity to restore membrane performance. This shows that membrane cleaning comes at the costs of a more stable bacterial community that is increasingly difficult to remove.Photo-oxidation of chemical warfare agents is considered a promising strategy to cope with threats from accidental or intentional release. In this study, heterostructure photocatalysts comprising different amounts of zirconium oxide (ZrO2) over carbon nitride (CN) were synthesized via simple thermal exfoliation, followed by a precipitation method. The successful photocatalytic detoxification activity of the as-prepared photocatalyst was analyzed against 2-chloroethyl ethyl sulfide (CEES) under simulated solar light and natural sunlight irradiation in dry and humid air. As the CN/ZrO2 demonstrated a high surface area and oxygen doping, the addition of small amounts of the ZrO2 phase could lead to enhanced photoreactivity in surface chemistry. The as-prepared (CN/ZrO2-II) degraded 95% of CEES under simulated solar light and 70% under natural sunlight within 90 min. Elamipretide cell line The photo-detoxification of CEES was associated with the generation of holes (h+) and activation of oxygen to superoxide radicals (•O2). Based on analysis results, a reaction mechanism was suggested. The activity of the used photocatalyst could be recovered to 90% of the fresh photocatalyst activity via simple water washing. However, as sulfurous compounds were accumulated on the surface in subsequent cyclic tests, solvent washing was also suggested to maintain high detoxification performance.An essential step in human biomonitoring or molecular epidemiology programs is to estimate human exposure to environmental chemicals. Despite significant progress in the capabilities of analytical methods, the number of pollutants and their metabolites keeps increasing continuously. Some of these relatively unknown chemicals of emerging concern (CECs) may pose significant health risks to humans and biota, but remain virtually undetected in traditional HBM-studies. Non-target and suspect screening techniques based on high-resolution mass spectrometry (HRMS) perform the detection and identification of compounds without any a priori compound selection or chemical information and provide a mor