Evaluation of E. coli biofilm as a protective barrier against microbiologically influenced deterioration of concrete (MICD) under mesophilic temperatures.

In this study, Escherichia coli DH5α biofilm was evaluated for its potential to control and minimize microbiologically influenced concrete deterioration (MICD) under mesophilic temperatures (37 °C). Escherichia coli DH5α biofilm was first grown on Portland cement mortar disks for 8 days. Mortar disks were then exposed to two different types of sulfur oxidizing bacteria (SOB) (Thiobacillus neapolitanus and Thiobacillus thiooxidans), which use sulfur compounds as substrate and oxidize them to sulfate and sulfuric acid. The effectiveness of the biofilm against MICD was evaluated by measuring pH, sulfate, calcium concentrations in the reactors and surface analysis of the mortar samples using X-ray diffraction and visual inspection. Overall, the results indicate that the E. coli DH5α biofilm showed good protection against MICD induced by SOB at 37 °C.

Evaluation of biofilm performance as a protective barrier against biocorrosion using an enzyme electrode.

Sulfide is known to be an important factor in microbiologically influenced corrosion (MIC) of metals and concrete deterioration in wastewater treatment structures and sewer pipelines. A sulfide biosensor was used to determine the effectiveness of Escherichia coli DH5 alpha biofilm as a protective barrier against MIC. The biofilm was shown to be effective in protecting surfaces from sulfide and helping to reduce MIC using amperometric measurements. The results also indicated that the growth conditions of E. coli DH5 alpha may have an impact on the performance of the biofilm as a sulfide barrier. The simple method provided in this work enables the comparison of several microbial biofilms and selection of the ones with potential to prevent MIC in a relatively short time.

Utilization of the auditory consonant trigram test to screen for cognitive impairment in patients with multiple sclerosis: comparison with the paced auditory serial addition test.

Several screening methods have been evaluated, but most of them are insensitive to MS-related cognitive impairment. The Auditory Consonant Trigram (ACT) test, which contains core features required for a working memory task, has been used to test neuro-cognitive function in different samples of patients to examine the status of working memory. The aim of the present study was to investigate the correlation between ACT and the Paced Auditory Serial Addition Test (PASAT), and the usefulness of ACT for evaluating the cognitive impairment in MS in a brief visit A total of 109 consecutive patients with definite MS were included. The patients were administered ACT, PASAT and EDSS. Mean PASAT score and mean ACT score were 46.19 +/- 8.51 and 45.30 +/- 9.07, respectively. Correlations between EDSS and PASAT, and EDSS and ACT were moderately strong. The correlation between ACT and PASAT was very strong (r = 0.831, P < 0.01). The mean time required to perform ACT was significantly shorter than PASAT (7.25 +/- 4.72 and 14.70 +/- 6.97 minutes, respectively). In conclusion, as a relatively brief measure of working memory, ACT was well accepted by MS patients and has a strong correlation with PASAT. Thus, ACT might be used for rapid evaluation of cognitive impairment in patients with multiple sclerosis.

Effect of extracellular polymers on freeze-thaw conditioning of activated sludge.

In this study, the effects of extracellular polymers on freeze-thaw conditioning of activated sludge are investigated. Various physical and chemical extraction methods including centrifugation, blending, heat, EDTA, EGTA, and NaOH extraction were used to remove extracellular material from sludge matrix. The improvements in freeze-thaw conditioning were evaluated by commonly used measures of sludge dewaterability. The results of this study indicate that removal of extracellular polymers using relatively gentle extraction methods before freeze-thaw conditioning improves the sludge dewaterability after the freeze-thaw. In addition to extracellular polymers, cations also play an important role in determining the freeze-thaw effectiveness on activated sludge. Best dewaterability is achieved when both extracellular polymers and cations are removed from activated sludge before freeze-thaw conditioning.

Effect of dissolved organic material and cations on freeze-thaw conditioning of activated and alum sludges.

Freeze-thaw conditioning effectively dewaters alum and activated sludges, but it works better on alum sludge than it does on activated sludge. The main difference between alum sludge and activated sludge is that activated sludge has high concentrations of both dissolved organic material and ions. Dissolved organic material and ions may possibly alter the freezing process and decrease the effectiveness of freeze-thaw conditioning on activated sludge. The objective of this study is to investigate the effect of dissolved organic material and cations on freeze-thaw conditioning of sludges, and to improve the effectiveness of freeze-thaw conditioning on activated sludge. The results of this study show that although protein, carbohydrate and cation concentrations in activated sludge supernatant are initially high, they dramatically increase after freeze-thaw conditioning. The increase is likely to come from the release of extracellular and intracellular material to sludge supernatant. The observed increase in the DNA concentration in activated sludge supernatant after freeze-thaw conditioning indicates that freeze-thaw causes cell disruption. Alum sludge supernatant, on the other hand, initially contains low concentrations of proteins, carbohydrates and cations which do not noticeably change after freeze-thaw conditioning. When ECPs (extracellular polymers) and cations are extracted from activated sludge before freeze-thaw conditioning. the sludge settles and dewaters better after the freeze-thaw. The resulting aggregates are smaller and denser resembling the "coffee ground" aggregates of alum sludge.