Nano-Sized Fume Biogas Production from Food Waster Using Semi-Continuous Anaerobic Digester.

In this study, the nano-sized fume biogas production from food waste was investigated using lab scale semi-continuous stirred tank reactor (SCSTR) at 35 °C with 30d HRT and 30L working volume. The mesophilic digestion test was performed with three different feed materials (food waste) and food to microorganism (F/M) ratios (0.13, 0.34, and 0.27) in the same experiment. The results showed that the F/M ratios significantly affected the biogas production rate. The highest production rate was obtained at F/M ratio of 0.13. Nano-sized fume biogas produced in anaerobic digestion consists of 68.7% CH4, 31.2% CO2 and 30~200 nm particle. The average nano-sized fume biogas and methane production of digester were 29.96 L/Kg versus day-1 and 20.58 L/Kg versus day-1, respectively. The CH4 could be calculated as the heat energy 1.85 Kcal/Kg VS day-1. The digestion was operated without addition of chemicals or nutrients into the system.

Thermal conductivity characteristics of dewatered sewage sludge by thermal hydrolysis reaction.

The purpose of this study is to quantify the thermal conductivity of sewage sludge related to reaction temperature for the optimal design of a thermal hydrolysis reactor. We continuously quantified the thermal conductivity of dewatered sludge related to the reaction temperature. As the reaction temperature increased, the dewatered sludge is thermally liquefied under high temperature and pressure by the thermal hydrolysis reaction. Therefore, the bound water in the sludge cells comes out as free water, which changes the dewatered sludge from a solid phase to slurry in a liquid phase. As a result, the thermal conductivity of the sludge was more than 2.64 times lower than that of the water at 20. However, above 200, it became 0.704 W/m* degrees C, which is about 4% higher than that of water. As a result, the change in physical properties due to thermal hydrolysis appears to be an important factor for heat transfer efficiency. Implications: The thermal conductivity of dewatered sludge is an important factor the optimal design of a thermal hydrolysis reactor. The dewatered sludge is thermally liquefied under high temperature and pressure by the thermal hydrolysis reaction. The liquid phase slurry has a higher thermal conductivity than pure water.

2-D DIGE and MS/MS analysis of protein serum expression in rats housed in concrete and clay cages in winter.

In a previous study, we examined the physiological responses of male Sprague-Dawley rats over a 4-week exposure to concrete and clay cages. No general toxicological changes were observed in rats exposed to either of the two cage types in summer. Under winter conditions, however, various general toxicological effects were detected in rats housed in concrete cages, although rats housed in clay cages showed no such effects. The infrared thermographic examination indicated that skin temperature in the concrete-housed rats was abnormally low, but not so in the clay-housed rats. We examined proteomic changes in the serum of rats housed in winter in concrete and clay cages using two-dimensional differential in-gel electrophoresis and mass spectrometry/mass spectrometry. Five proteins were identified and quantitatively validated; all were cold stress-induced, acute phase proteins that were either up-regulated (haptoglobin) or down-regulated (alpha-1-inhibitor III, alpha-2u globulin, complement component 3, and vitamin D-binding protein) in the concrete-housed rats. These results suggest that the 4-week exposure to a concrete cage in winter elicited a typical systemic inflammatory reaction (i.e. acute phase response) in the exposed rats.

Surface modification of orthodontic wires with photocatalytic titanium oxide for its antiadherent and antibacterial properties.

OBJECTIVE: To test the antiadherent and antibacterial properties of surface modification of orthodontic wires with photocatalytic titanium oxide (TiO(2)). MATERIALS AND METHODS: TiO(2) was coated on the surface of the orthodontic wires by a sol-gel thin film dip-coating method. Bacterial adhesion to the wires was evaluated by the weight change of the wires. The antibacterial activity of the surface-modified orthodontic wires was demonstrated by the dilution agar plate method for Streptococcus mutans and spectrophotometry for Porphyromonas gingivalis. RESULTS: The orthodontic wires coated with the photocatalytic TiO(2) showed an antiadherent effect against S. mutans compared with the uncoated wires. The bacterial mass that bound to the TiO(2)-coated orthodontic wires remained unchanged, whereas that of the uncoated wires increased by 4.97%. Furthermore, the TiO(2)-coated orthodontic wires had a bactericidal effect on S. mutans and P. gingivalis, which cause dental caries and periodontitis, respectively. The antiadherent and antibacterial mechanisms of TiO(2) to break down the cell wall of those bacteria were revealed by scanning electron microscopy. CONCLUSION: The surface modification of orthodontic wires with photocatalytic TiO(2) can be used to prevent the development of dental plaque during orthodontic treatment.