Search

Hydrogen sulfide (H2S) is known to participate in bacteria-induced inflammatory response in periodontal diseases. Therefore, it is necessary to quantify H2S produced by oral bacteria for diagnosis and treatment of oral diseases including halitosis and periodontal disease. In this study, we introduce a paper-based colorimetric assay for detecting bacterial H2S utilizing silver/Nafion/polyvinylpyrrolidone membrane and a 96-well microplate. This H2S-sensing paper showed a good sensitivity (8.27 blue channel intensity/μM H2S, R2 = 0.9996), which was higher than that of lead acetate paper (6.05 blue channel intensity/μM H2S, R2 = 0.9959). We analyzed the difference in H2S concentration released from four kinds of oral bacteria (Eikenella corrodens, Streptococcus sobrinus, Streptococcus mutans, and Lactobacillus casei). Finally, the H2S level in Eikenella corrodens while varying the concentration of cysteine and treatment time was quantified. This paper-based colorimetric assay can be utilized as a simple and effective tool for in vitro screening of H2S-producing ability of many bacteria as well as salivary H2S analysis.

This paper suggests policy implications for the mitigation of resident conflict in public rental apartment complexes in South Korea. Employing a nation-wide disaggregate dataset from the 2011 Korea Housing Survey for Public Housing Residents, we developed a probability model of the occurrence of conflicts among the residents in mixed-tenure public housings. The results showed that spatial configuration of dwelling units between rental and privately owned units, management system, and resident’s organization played important roles in the occurrence of resident’s conflict. The degree of spatial integration showed a significant relationship to the occurrence of residents’ conflicts in that two types of mixing (i.e., segregated and segmented) were positively associated with the increase in conflicts among residents, whereas the other two types (i.e., “line-mix” and “random-mix”) with higher levels of spatial integration had a negative association with it. Although both “line-mix” and “random-mix” can be considered as a type of spatial configuration with higher level of spatial integration, it was found that only “random-mix” was statistically significant. It is suggested that “a pepper-potted strategy” needs to be implemented to mitigate residents’ conflicts in mixed-tenure public housing developments in South Korea.