lishment of a biofilm, which can be avoided by disinfection of the machine with a solution of chlorine (250 ppm). We apply chlorine disinfection in our systems every 2 weeks. The water filter is replaced weekly by a sterilized 0.2 μm membrane filter. The literature mentioned in Russell’s review, the results from our experiments, and the precautions for recontamination mentioned above made us de...

INTRODUCTION A mandatory requirement of root canal therapy is that the obturation and restoration of the tooth must seal the root canals both apically and coronally to prevent leakage and percolation of oral fluids and to prevent recontamination of disinfected canals. Apicoectomy (apicectomy/root-end resection) with retrograde obturation is a widely applied procedure in endodontics, when all ef...

Introduction. Root perforations may occur following endodontic treatment, thus compromising the root integrity and treatment outcome. Case Report. A patient presented with a canal perforation an earlier of upper left lateral incisor (tooth 22). Once diagnosis symptomatic periapical periodontitis was established, decision made to retreat using mineral trioxide aggregate perform apicoectomy. The ...

The invasion of DNAPL into fractured low permeability deposits results in the formation of secondary source zones that represent a long-term source of VOCs to adjacent aquifers. We present data from a site underlain by a fractured mudstone contaminated with TCE DNAPL that was poised for release following remediation of the overlying aquifer. Observations of contaminant distributions and fractur...

Recontamination during transport and storage is a common challenge of water supply in low-income settings, especially if collected manually. Chlorination strategy to reduce recontamination. We assessed seven low-cost, non-electrically powered chlorination devices gravity-driven membrane filtration (GDM) kiosks eastern Uganda: one floater, two in-line dosers, three end-line dosers (tap-attached)...

In this work we introduce and study a pursuit-evasion game in which the search is performed by heterogeneous entities. We incorporate heterogeneity into classical edge problem considering edge-labeled graphs: once strategy initially assigns labels to searchers, each searcher can be only present on an of its own label. prove that not monotone even for trees give instances number recontamination ...

A field study assessing the sustainability and efficacy of 55 biosand filters installed during 1999-2010 was conducted in the Artibonite Valley, Haiti during 2011. Twenty-nine filters were still in use. Duration of filter use ranged from < 1 to 12 years. Water quality, microbial analysis, and flow rate were evaluated for each functioning filter. Kaplan-Meier analysis of filter lifespans showed ...

We consider a special variant of pursuit-evasion game called lions and contamination. In graph whose vertices are originally contaminated, set walks around the each lion clears contamination from every vertex it visits. The contamination, however, simultaneously spreads to any adjacent not occupied by lion. study relationship between different types clearings graphs, such as which do allow reco...

Abstract Spore-forming bacteria form the most diverse and complex group of in terms their elimination from dairy chain, due to ability highly resistant spores. As ubiquitous microorganisms, spore-formers can enter product along milk-processing continuum different sources, subsequently cause spoilage various types products. The important classes spore-forming relevant industry are Bacilli Clostr...

Natural loss of hydrocarbons was often low from mussel (Mytilus trossulus) beds (which were typically not cleaned after the Exxon Valdez oil spill), thus this habitat remained a long-term source of oil. Consequently, experimental restoration of nine contaminated beds was attempted in 1994; mussels were removed, contaminated surface sediment was replaced (33 metric tons), and original mussels we...