ABSTRACT
The development of methods to reuse large volumes of plastic waste is essential to curb the environmental impact of plastic pollution. Plastic-reinforced cementitious materials (PRCs), such as plastic-reinforced mortar (PRM), may be potential avenues to productively use large quantities of low-value plastic waste. However, poor bonding between the plastic and cement matrix reduces the strength of PRCs, limiting its viable applications. In this study, calcium carbonate biomineralization techniques were applied to coat plastic waste and improved the compressive strength of PRM. Two biomineralization treatments were examined: enzymatically induced calcium carbonate precipitation (EICP) and microbially induced calcium carbonate precipitation (MICP). MICP treatment of polyethylene terephthalate (PET) resulted in PRMs with compressive strengths similar to that of plastic-free mortar and higher than the compressive strengths of PRMs with untreated or EICP-treated PET. Based on the results of this study, MICP was used to treat hard-to-recycle types 3-7 plastic waste. No plastics investigated in this study inhibited the MICP process. PRM samples with 5% MICP-treated polyvinyl chloride (PVC) and mixed type 3-7 plastic had compressive strengths similar to plastic-free mortar. These results indicate that MICP treatment can improve PRM strength and that MICP-treated PRM shows promise as a method to reuse plastic waste.
ABSTRACT
OBJECTIVES: This study aims to evaluate the serum levels of hemoglobin, vitamin B12 and folic acid in patients with recurrent minor aphthous stomatitis. PATIENTS AND METHODS: Between June 2010 and January 2012, a total of 112 patients including 57 with recurrent aphthous stomatitis (study group; 30 males 27 females; mean age 36.7±13.9 years; range 13 to 74 years) and 45 with chronic tinnitus patients without recurrent aphthous stomatitis (control group; 18 males 27 females; mean age 39.7±15.1 years; range 20 to 80 years) who were admitted to our clinic were included in this study. The serum hemoglobin, vitamin B12 and folic acid levels of the patients were measured and statistically compared. RESULTS: There was no significant difference in serum levels of hemoglobin and folic acid between the groups. Serum levels of vitamin B12 were significantly lower in the study group, compared to the control group (p<0.05). Serum levels of hemoglobin and folic acid were significantly lower in women compared to men in both groups (p<0.05). CONCLUSION: Vitamin B12 deficiency, but not lower levels of folic acid and hemoglobin, may play a role in the underlying etiology of aphthous stomatitis. Vitamin B12 supplements may be added to the treatment of recurrent aphthous stomatitis.