No abstract

Chlorine-containing solutions are used for broad disinfection purposes. Water disinfection literature suggests that their disinfectant action depends on pH values as this will influence the available free chlorine forms. Hypochlorous acid (HOCl) has been suggested to have an antimicrobial effect around 80-100 times stronger than the hypochlorite ion. The aim of this paper was to review the influence of pH changes on the efficacy of chlorine-containing endodontic irrigating solutions. An electronic and hand search (articles published through to 2010, including 'in press' articles; English language; search terms 'root canal irrigants AND sodium hypochlorite or hypochlorous acid or superoxidized water or electrochemically activated solution'; 'antimicrobial action AND sodium hypochlorite or hypochlorous acid or superoxidized water or electrochemically activated solution'; 'tissue dissolution AND sodium hypochlorite or hypochlorous acid or superoxidized water or electrochemically activated solution'; 'smear layer AND sodium hypochlorite or hypochlorous acid or superoxidized water or electrochemically activated solution') was performed to identify publications that compared chlorine water solutions with different pH. Of 1304 publications identified, 20 were considered for inclusion in the review. The search resulted in the retrieval of articles studying sodium hypochlorite (NaOCl), superoxidized waters (SOW) and sodium dichloroisocyanurate (NaDCC). Regarding antimicrobial efficacy, the literature suggested that reducing the pH value of NaOCl to between 6 and 7.5 would lead to improved action; SOW was described as having a lower antimicrobial effect. The tissue dissolution activity NaOCl decreased when the pH reached values between 6 and 7.5; NaDCC and SOW had no clinically relevant tissue dissolution capability. Chlorine solutions of different characteristics appeared to have some cleaning efficacy although they should to be used in conjunction with chelating and/or detergent agents.

No abstract

No abstract

Natural organic matter (NOM) from seawater is a complex mixture of compounds that has only been roughly characterized. In this study, advanced techniques such as fractionation based on adsorptiondesorption dynamics (on XAD ® resins), liquid chromatography-organic carbon detection (LC-OCD), excitation-emission matrix (EEM) fluorescence and membrane separation techniques were applied to the characterization of seawater NOM. Conventional analyses have shown that Mediterranean coastal seawater has a low NOM content, slightly aromatic and poorly biodegradability. Advanced analysis permitted better characterization by separating the NOM into different fractions. The NOM was found to be mainly hydrophilic (HPI) (70%) and slightly transphilic (TPI) (24%) from XAD fractionation. LC-OCD showed the seawater to be composed mainly of humic substances (HSs) and low molecular weight (LMW) neutrals that accounted for 37 and 40% of the dissolved organic carbon, respectively. The HSs contained hydrophobic, TPI and HPI compounds, revealing advanced hydrolysis, whereas the LMW neutrals were HPI compounds. Membrane separation revealed that most of the seawater NOM had a MW of <1 kDa, confirming that the HSs were in an advanced state of degradation. We have also shown that seawater NOM with a MW of >1 kDa contains mainly aromatic proteins, which are more biodegradable than whole seawater NOM.

No abstract

No abstract

No abstract