รายงานวิจัยโครงการคุณลักษณะของอนุภาคและโพลีไซคลิกอะโรแมติกไฮโดรคาร์บอน จากเครื่องยนต์ที่ใช้น้ำมันปาล์มผสมเชื้อเพลิง

Prince of Songkla Universit

Urinary 1-Hydroxypyrene Levels in Workers Exposed to Polycyclic Aromatic Hydrocarbon from Rubber Wood Burning

Background: Urinary 1-hydroxypyrene (1-OHP) was selected as a biomarker of polycyclic aromatic hydrocarbons (PAHs) to explore the accumulation level in the bodies of workers at rubber smoke sheet factories in southern Thailand. Methods: Spot urine samples were taken from four groups of workers from June 2006 to November 2007. The nonexposure or control groups included habitual cigarette smokers and nonsmokers. The other two groups were workers exposed to particle-bound PAHs from rubber wood smoke and they were nonsmokers. All spot urine samples were analyzed for 1-OHP and creatinine levels. Results: The mean ± standard deviation urinary 1-OHP in the control group of habitual smokers and the nonsmokers was 0.24 ± 0.16 μmol/mol creatinine and not-detected to 0.14 μmol/mol creatinine, respectively. In the workers, the 1-OHP levels on workdays had no significant difference from the 1-OHP levels on the days off. The yearly average 1-OHP level was 0.76 ± 0.41 μmol/mol creatinine whereas the average 1-OHP level during 10 consecutive workdays was 1.06 ± 0.29 μmol/mol creatinine (p > 0.05). Conclusion: The urinary 1-OHP levels of workers exposed to PAHs were high. The accumulation of 1-OHP in the body was not clear although the workers had long working hours with few days off during their working experience. Therefore, a regular day off schedule and rotation shift work during high productive RSS should be set for RSS workers

Effects of Food Viscosity on Swallowing Velocity in Pharynx for Different Groups of Age and Gender

Abstract Dysphagia can be treated using methods such as direct food swallowing. However, the viscosity of food can be an obstacle to patients. To prepare appropriate food for patients, nutritionists need to understand the influence of food viscosity on the velocity of bolus transport in the pharynx. In the present study, the effects of the viscosity of shearthinning food on bolus velocity are investigated. Food viscosity in the range of 95 to 1368 mPa·s (nectar to honey consistency) is tested. Thai volunteers were classified into 3 groups, namely young adult, adult, and elderly. Videofluorographic recording was performed and bolus velocity was calculated. The average tail bolus velocity of young adult volunteers while swallowing food with a nectar-honey consistency was about 99-125 mm/s for males and 77-90 mm/s for females. The values were 97-117 mm/s for males and 76-80 mm/s for females in the adult group, and 87 mm/s for males and 85 mm/s for females in the elderly group. Swallowing characteristic of male is developed in natural style, where velocity decreases with increasing viscosity. However, the swallowing characteristic of female is developed to a full performance, where swallowing power is at maximum regardless of viscosity. The velocity of food swallowing depends on food viscosity. A suitable swallowing velocity for healthy persons can be used for the design of food for dysphagic patients to yield similar velocity

Single-phase and multiphase models for temperature and relative humidity calculations during forced convection in a rubber-sheet drying chamber

Computational fluid dynamics modelling of single-phase and multiphase flows was used to simulate the temperature and relative humidity at various locations in an empty rubber-sheet drying chamber. In all planes, unlike the single-phase model, the multiphase model’s temperature distribution is relatively uniform, and the temperature deviations are 0.01-4.73°C in the bottom plane, 0.02-4.05°C in the middle plane, and 0.01-3.84°C in the top plane. The single-phase model results in temperature deviations of 0.55-6.63°C, 0.02-6.02°C and 0.36-3.89°C in the bottom, middle and top planes respectively. Thus, the multiphase model is deemed superior. The inclusion of water vapour in the multiphase model increases the agreement between model and experimental temperature data. The largest temperature deviations occur at the centre-frontal positions of all planes owing to the turbulence of the hot gas at the inlet. In all planes the relati ve humidity is almost uniform, except near the centre-frontal area of the bottom plane. Clearly, the multiphase model is more appropriate for simulating chambers containing rubber sheets, though the diffusion of moisture from rubber sheets needs to be considered as well

Drying of Rhinacanthus nasutus (Linn.) Kurz. using a solar dryer incorporated with a backup thermal energy storage from wood combustion

An indirect, natural convection, solar cabinet dryer incorporated with a backup thermal energy storage from wood combustion was designed and tested with the Thai herb, Rhinacanthus nasutus (Linn.) Kurz. Most of Thai herbs are widely used as traditional medicine and drying is an initial step in the production process. Solar dryer with a biomass backup heating system is the most feasible solution to drying in Thailand. In this work, a 4 m x 5 m solar collector was used to absorb solar radiation for heating the incoming air during the daytime, while a biomass burner was used to supply heat when solar energy was not possible. Heat from fuelwood combustion was accumulated in the thermal storage system made of bricks, and was used to heat up the incoming air. Results showed that the herb was dried uniformly and the temperature inside the drying cabinet could be maintained above 50ºC for more than 10 hours. Thermal efficiency when using solar energy was 10.5%, but the value was less than 1% when using the heat from biomass burning. This resulted from the low moisture content of the products after being dried by the solar energy. The dryer is beneficial to the operators, particularly in southern Thailand, where continuous drying is required. This dryer is by no means limited to drying of the herb. Currently, four dryers of the same model have been used by farmer groups in southern Thailand for drying bananas, several types of herbs, fish, and other products. In economic consideration, its payback period is 5.5 years when compared with the LPG-equipped dryer. When the total cost and production capacity are considered, its payback period is about 6 years

Drying of Rhinacanthus nasutus (Linn.) Kurz. using a solar dryer incorporated with a backup thermal energy storage from wood combustion

Abstract Kirirat, P., Prateepchaikul, G., Navasut, J., Na Nakorn, N. and Tekasakul, P. Drying o