Polycyclic aromatic hydrocarbons exposure in residents living near a cement factory with kilns.

PURPOSE: This study was performed to investigate polycyclic aromatic hydrocarbons (PAHs) exposure in the area around a cement factory with kilns using waste, including refuse plastic fuel. METHODS: Atmospheric total suspended particulates (TSPs) for each of an exposed area and a non-exposed area were collected. Similarly, urine samples were collected from 330 subjects in the exposed area and 126 subjects in the non-exposed area. Gas chromatography with mass spectrometry was used to analyze PAHs in the collected TSP samples and the PAH metabolites, urinary 2-naphthol (2-NAP) and 1-hydroxypyrene (1-OHP), of the residents. The concentrations of urinary 2-NAP and 1-OHP were adjusted by creatinine concentrations. RESULTS: The atmospheric concentrations of PAHs, including naphthalene and pyrene, were higher in the exposed area than those in the non-exposed area. The geometric means (GMs) of the urinary 2-NAP concentrations in the exposed and non-exposed groups without work experience were 4.06 and 1.55 µg/g creatinine, respectively. The GMs of the urinary 1-OHP concentrations were 0.26 and 0.14 µg/g creatinine, respectively. The results showed that the concentrations of PAH metabolites were significantly higher in the exposed group than those in the non-exposed group (p < 0.001). Multiple linear regression analysis with the log-transformed urinary 2-NAP and 1-OHP concentrations and other variables indicated a strong correlation of residence in the exposed area and smoking with an increase in the urinary 2-NAP and 1-OHP concentrations. CONCLUSIONS: In addition to the known risk factors, this study indicated that living near a cement factory with kilns is also a risk factor for PAH exposure.

Effects of process conditions on the properties of silicon nanoparticles synthesized by gas phase reactions using inductive coupled plasma.

Silicon nanoparticles were synthesized by passing monosilane through a quartz tube wrapped with Inductive Coupled Plasma (ICP) coil. Microstructures of synthesized silicon nanoparticles were investigated with various process conditions. To research the effects of process parameters on the properties of nanoparticles, we verified the partial pressure of monosilane, the plasma power and the working pressure. The highly crystalline silicon nanoparticles were only achieved at the proper partial pressure of the reactive gas and plasma power. Partial pressure determined not only the particle size but also the crystallinity of the nanoparticles. The plasma power was controlled from 50 to 100 W which determined not the particle size but the crystallinity of nanoparticles. Especially, too low a power resulted in amorphous particles with an average sizes of 5.25 nm. As the working pressure increased, the amount of produced nanoparticles linearly increased and the maximum production yield was at 76 mg/hr. Controlling those parameters, we achieved monodispersed single crystalline silicon nanoparticles with an average diameter of 7.52 nm. Silicon nanoparticles in this study can be applied to light absorbing material for solar cells and the wavelength down-converter material of Light Emitting Diode (LED).

Toluene vapor capture by activated carbon particles in a dual gas-solid cyclone system.

Capturing of odorous compounds such as toluene vapor by a particulate-activated carbon adsorbent was investigated in a gas-solid cyclone, which is one type of mobile beds. The test cyclone was early modified with the post cyclone (PoC) and a spiral flow guide to the vortex finder. The proposed process may contribute to the reduction of gases and dust from industrial exhausts, especially when dealing with a low concentration of odorous elements and a large volume ofdust flow. In this device, the toluene capturing efficiency at a 400 ppm concentration rose up to 77.4% when using activated carbon (AC) particles with a median size of 27.03 microm. A maximum 96% of AC particles could be collected for reuse depending on the size and flow rate. The AC regenerated via thermal treatment showed an adsorption potential up to 66.7% throughout repeated tests.

Decomposition of VOCs using serial surface dielectric barrier discharge reactors.

Decomposition of two typical volatile organic compounds (VOCs): toluene and methyl ethyl ketone (MEK), was investigated by introducing the complete energy yield (i.e. amount of VOCs totally converted to CO and CO2 for every 1 kWh of electrical usage) and specific energy density (SED) for the non-thermal plasma technology. Three dielectric barrier discharge reactors of which SED range was 55 J/L to 283 J/L at a flow rate of 1 L/min were connected in a 3-reactor arranged in series using interconnecting tubes in the inlets and outlets. As a result of the serial reactor design, the energy efficiency of the system improved, and in particular, 7% of increase was found in at the same level of energy consumption. The mixed phase of VOCs (toluene and MEK) showed MEK as a limiting species in this study. As the inlet concentration rose from 20 to 100 ppmv, both energy yield and complete energy yield increased from 0.8 to 9.2 g/kWh and from 0.8 to 2.3 g/kWh, respectively.

Efficacy of a dexamethasone-eluting nitinol stent on the inhibition of pseudo-intimal hyperplasia in a transjugular intrahepatic portosystemic shunt: an experimental study in a swine model.

OBJECTIVE: We wanted to evaluate the feasibility and efficacy of using a dexamethasone (DM)-eluting nitinol stent to inhibit the pseudo-intimal hyperplasia following stent placement in the transjugular intrahepatic portosystemic shunt tract (TIPS) of a swine. MATERIALS AND METHODS: Fifteen stents were constructed using 0.15 mm-thick nitinol wire; they were 60 mm in length and 10 mm in diameter. The metallic stents were then classified into three types; type 1 and 2 was coated with the mixture of 12% and 20%, respectively, of DM solution and polyurethane (PU), while type 3 was a bare stent that was used for control study. In fifteen swine, each type of stent was implanted in the TIPS tract of 5 swine, and each animal was sacrificed 2 weeks after TIPS creation. The proliferation of the pseudo-intima was evaluated both on follow-up portogram and pathologic examination. RESULTS: One TIPS case, using the type 1 stent, and two TIPS cases, using the type 2 stent, maintained their luminal patency while the others were all occluded. On the histopathologic analysis, the mean of the maximum pseudo-intimal hyperplasia was expressed as the percentage of the stent radius that was patent, and these values were 51.2%, 50% and 76% for the type 1, 2, and 3 stents, respectively. CONCLUSION: The DM-eluting stent showed a tendency to reduce the development of pseudo-intimal hyperplasia in the TIPS tract of a swine model with induced-portal hypertension.