• The Journal of Advanced Prosthodontics
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• v.6 no.4
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• pp.272-277
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• 2014

PURPOSE. The purpose of this study was to investigate the impact of different surface treatment methods and thermal ageing on the bond strength of autopolymerizing acrylic resin to Co-Cr. MATERIALS AND METHODS. Co-Cr alloy specimens were divided into five groups according to the surface conditioning methods. C: No treatment; SP: flamed with the Silano-Pen device; K: airborne particle abrasion with $Al_2O_3$; Co: airborne particle abrasion with silica-coated $Al_2O_3$; KSP: flamed with the Silano-Pen device after the group K experimental protocol. Then, autopolymerized acrylic resin was applied to the treated specimen surfaces. All the groups were divided into two subgroups with the thermal cycle and water storage to determine the durability of the bond. The bond strength test was applied in an universal test machine and treated Co-Cr alloys were analyzed by scanning electron microscope (SEM). Two-way analysis of variance (ANOVA) was used to determine the significant differences among surface treatments and thermocycling. Their interactons were followed by a multiple comparison' test performed uing a post hoc Tukey HSD test (${\alpha}=.05$). RESULTS. Surface treatments significantly increased repair strengths of repair resin to Co-Cr alloy. The repair strengths of Group K, and Co significantly decreased after 6,000 cycles (P<.001). CONCLUSION. Thermocycling lead to a significant decrease in shear bond strength for air abrasion with silica-coated aluminum oxide particles. On the contrary, flaming with Silano-Pen did not cause a significant reduction in adhesion after thermocycling.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.269-275
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• 2014

The objective of this study was to investigate the performance characteristics of an inline mixing and coagulation system for water treatment based on the process intensification concept. Three-stage inline mixing and coagulation system was composed of the reservoirs of source wastewater, the fixed quantity injection pumps of coagulants, the mixing and coagulation tubes, a sedimentation tank and a control panel. In the equal dosage of coagulant and coagulant aids, the turbidity removal with increasing the dosage of coagulant aids was about 3 times higher than that with increasing the dosage of coagulant. In the condition of the equal mixing and coagulation time, the turbidity removal of inline mixing and coagulation system was about 4.6 times higher than that of mechanical type.

• Environmental Engineering Research
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• v.25 no.4
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• pp.614-621
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• 2020

Antibiotic pollution is one of the factors contributing to the spread of antibiotic-resistant bacteria in the environment. Advanced oxidation and irradiation processes have been introduced to eliminate antibiotics from water and wastewater. However, few studies have reported the toxic effects of residual antibiotics and their byproducts induced by a treatment system. In this study, we compared the efficacies of chemical (high-performance liquid chromatography (HPLC)) and biological (antimicrobial susceptibility test) assays for measuring the concentrations of residual antibiotics after gamma irradiation for degrading amoxicillin, cephradine, lincomycin, and tetracycline. The concentrations of residual antibiotics estimated using the two assay methods were almost identical, except cephradine. In the case of cephradine, inhibited bacterial growth was observed that was equivalent to twice the concentration measured by HPLC in the samples subjected to gamma irradiation. The observed inhibition of bacterial growth suggested the generation of potentially toxic intermediates following antibiotic degradation. These results indicate that biological and chemical assays should be used in concert for monitoring antibiotic contamination and the toxic derivatives of antibiotic degradation. The results demonstrate that these four antibiotics can be decomposed by 2.0 kGy gamma-irradiation without toxic effects of their byproducts.

• Nuclear Engineering and Technology
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• v.16 no.1
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• pp.36-46
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• 1984

Studied are the statistical thermal design (STD) methods that have been developed to satisfy the design basis which protects a pressurized water reactor (PWR) core against departure from nucleate boiling (DNB) during normal operations and anticipated transients. The objective of the statistical thermal design is to quantify the thermal design margin and to remove any excess conservatism from the DNB ratio calculations through statistically combining design parameter uncertainties, while still maintaining a high level of core protection. This report describes and compares the STD methods developed by the two U.S. reactor vendors (Westinghouse and B & W). Included are the characteristics of STD, statistical treatment of uncertainties, DNB design limit development methodology and the sample application of the STD technique to core thermal design analysis. It is observed that the STD methods developed by the two vendors are similiar to each other in principle, but different in the treatment of the uncertainties associated with the design parameters. The statistical thermal design is found to significantly improve the thermal design margin.

• The Journal of Advanced Prosthodontics
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• v.5 no.2
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• pp.98-103
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• 2013

PURPOSE. To evaluate the effects of hydrofluoric acid etching and Er,Cr:YSGG laser irradiation on the shear bond strength of resin cement to lithium disilicate ceramic. MATERIALS AND METHODS. Fifty-five ceramic blocks ($5mm{\times}5mm{\times}2mm$) were fabricated and embedded in acrylic resin. Their surfaces were finished with 1000-grit silicon carbide paper. The blocks were assigned to five groups: 1) 9.5% hydrofluoric-acid etching for 60 s; 2-4), 1.5-, 2.5-, and 6-W Er,Cr:YSGG laser applications for 60 seconds, respectively; and 5) no treatment (control). One specimen from each group was examined using scanning electron microscopy. Ceramic primer (Rely X ceramic primer) and adhesive (Adper Single Bond) were applied to the ceramic surfaces, followed by resin cement to bond the composite cylinders, and light curing. Bonded specimens were stored in distilled water at $37^{\circ}C$ for 24 hours. Shear bond strengths were determined by a universal testing machine at 1 mm/min crosshead speed. Data were analyzed using Kruskal-Wallis and Mann-Whitney U-tests (${\alpha}$=0.05). RESULTS. Adhesion was significantly stronger in Group 2 ($3.88{\pm}1.94$ MPa) and Group 3 ($3.65{\pm}1.87$ MPa) than in Control group ($1.95{\pm}1.06$ MPa), in which bonding values were lowest (P<.01). No significant difference was observed between Group 4 ($3.59{\pm}1.19$ MPa) and Control group. Shear bond strength was highest in Group 1 ($8.42{\pm}1.86$ MPa; P<.01). CONCLUSION. Er,Cr:YSGG laser irradiation at 1.5 and 2.5 W increased shear bond strengths between ceramic and resin cement compared with untreated ceramic surfaces. Irradiation at 6 W may not be an efficient ceramic surface treatment technique.

• Journal of the Korean GEO-environmental Society
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• v.3 no.4
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• pp.5-10
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• 2002

Pistia stratiotes(Water Lettuce) can be applied to remove inorganic pollutants from the wastewater for the advanced treatment. This study attempts to remove heavy metals from the secondary treated wastewater. Three different initial concentrations of heavy metals were applied as 0.5, 1.0 and 1.5 mg/L for Lead(Pb) and Chromium(Cr(VI)). In addition, the removal efficiency for the mixture of Lead and Chromium was also observed. The removal efficiency of Pb was in the range of 41.0~72.0% for Pb and it was in the range of 25.0~30.0% for Cr(VI) by Pistia stratiotes. The plants placed in static systems were able to remove the heavy metals in a few days of exposure. However, it was observed that the heavy metals affected produce phytotoxic effects on plants resulting in inhibition of chlorophyl synthesis, decrease in biomass production, and finally plant necrosis. The removal efficiencies of Pb and Cr(VI) by Pistia stratiotes were increased with plant growth.

• Microbiology and Biotechnology Letters
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• v.31 no.3
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• pp.264-270
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• 2003

A quantitative survey of the protozoa microfauna at bioreactor of advanced sewage treatment plant was carried out during a period of 11 months. In this study, 32 genera were identified, including 17 ciliates. The abundance of the important protozoa were compared with the operating parameters and water quality of the effluent of the plant using statistical procedure. Statistical analysis revealed a relationship between the abundance of some genera and removal rate. In particular, correlation analysis on the quality of effluent and protozoa indicated that Lepadella may be used as the bioindicator of TP removal and Trochilia, Entosiphon, Colepus may be used as the bioindicator of TN removal when water temperature was below $20^{\circ}C$.

• Journal of Pharmaceutical Investigation
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• v.37 no.2
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• pp.79-84
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• 2007

This study was aimed to establish analytical method of Bi to develop a guideline of the bioequivalence test of tripotassium dicitrato bismuthate (TDB). For this purpose, a simple, specific and sensitive inductively coupled plasma-mass spectrometry (ICP/MS) method were developed and validated in human plasma. Various concentrations of bismuth standard solution (0-25ng/mL) were prepared with distilled water and human blank plasma. To 10mL of the volumetric flasks, 2mL of blank plasma was added with 8ml of distilled water. Bi standard solution was added to prepare the calibration samples and injected into ICP-MS. The plasma samples obtained from volunteers given 3 tablets of bismuth (total 900mg as TDB) were analyzed as described above. As a result, the coefficients of variation were <20% in quantitation limit (0.2 ng/mL) and <15% at the rest of concentrations. The stability test by repeated freezing-thawing cycles showed that the samples were stable only for 24hr. The stability tested for samples with a short-term period of storage at room temperature and pre-treatment prior to the analysis showed very stable over 24hr. In 8 healthy Korean subjects received Denol tablets at the dose of 900mg bismuth, AUC, $C_{max},\;T_{max}$ and half-life $(t_{1/2})$ were determined to be $198.33{\pm}173.78 ng{\cdot}hr/mL,\;64.48{\pm}27.06 ng/mL,\;0.52{\pm}0.21 hr,\;and\;5.15{\pm}2.67 hr$, respectively, from the plasma bismuth concentration-time curves. In conclusion, the method was suitable for the determination of bismuth in human plasma samples and could be applied to bioequivalence test of bismuth tablet.

• Membrane Journal
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• v.14 no.2
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• pp.149-156
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• 2004

This work focused on the degradation of natural organic matter (NOM) present in lake water using a combined pkotocatalysisimicrofiltration (MF) process. The system performances were investigated in terms of organic removal efficiency and membrane permeability. The addition of iron oxide particles (IOP) into the photocatalytic membrane reactor improved initial NOM removal by sorption, but during photocatalysis the removal efficiency was reversed, probably due to the scattering of UV light by IOP. The modification of TiO$_2$ surfaces by IOP deposition was conducted to enhance the photocatalytic NOM removal efficiency. A minimal amount of Impregnation of IOP on TiO$_2$ surfaces was required to prevent the light scattering effect as well. The coating of MF membranes with IOP helped to improve the NOM removal efficiency while sorbing NOM by IOP. Regardless of tile operating conditions and particles addition examined, no significant fouling was occurring at a flux of 15 L/$m^2$-h during entire MF operation.

• The Journal of Advanced Prosthodontics
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• v.5 no.3
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• pp.270-277
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• 2013

PURPOSE. This study was aimed to determine the effect of two chemically distinct denture cleansers and water on the surface hardness of acrylic and silicone based soft denture liners at various time intervals. MATERIALS AND METHODS. Two commonly used commercial resilient liner material were selected based on their chemical composition (silicone- and acrylic-based soft liners) for this investigation. 120 cylindrical specimens were made of $15mm{\times}10mm$ dimensions (according to ASTM: D-2240-64T) in a custom made metal mold. All specimens were stored in artificial saliva throughout the study. Forty specimens were cleansed daily in 0.5% sodium hypochlorite solution; forty were cleansed in sodium perborate and remaining forty specimens were daily rinsed in water. Testing was done at 1 week, 1 month, 3 months and 6 months for surface hardness using a Shore A Durometer. A mean of 3 reading for each sample was subjected to one-way ANOVA, Post Hoc test and pair-t test for statistical analysis. P values of less than 0.05 were taken as statistically significant. RESULTS. Surface hardness of all the samples was significantly higher after a period of 6 months irrespective of the cleansing treatment. Minor changes were observed between control, sodium hypochlorite and sodium perborate groups with time. Greater change was observed in surface hardness of acrylic-based soft denture liners as compared to silicone-based soft liners for all groups, as time progressed. CONCLUSION. Silicone-based soft denture liners performed significantly better in all cleansing treatments than acrylic-based soft denture liners.