• Journal of dental hygiene science
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• v.16 no.1
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• pp.70-76
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• 2016

The objective of this study was to fabricate hydroxyapatite (HA) containing titania layer by HA blasting and anodization method to obtain advantages of both methods and evaluated biocompatibility. To fabricate the HA containing titania layer on titanium, HA blasting treatment was performed followed by microarc oxidation (MAO) using the electrolyte solution of 0.04 M ${\beta}$-glycerol phosphate disodium salt n-hydrate and 0.4 M calcium acetate n-hydrate on the condition of various applied voltages (100, 150, 200, 250 V) for 3 minutes. The experimental group was divided according to the surface treatment procedure: SM (simple machined polishing treatment), HA, MAO, HA+MAO 100, HA+MAO 150, HA+MAO 200, HA+MAO 250. The wettability of surface was observed by contact angle measurement. Biocompatibility was evaluated by cell adhesion, and cell differentiation including alkaline phosphatase activity and calcium concentration with MC3T3-E1 cells. The porous titanium oxide containing HA was formed at 150 and 200 V. These surfaces had a more hydrophilic characteristic. Biocompatibility was demonstrated that HA titania composite layer on titanium showed enhanced cell adhesion, and cell differentiation. Therefore, these results suggested that HA containing titania layer on titanium was improved biological properties that could be applied as material for dental implant system.

• Korean Journal of Clinical Laboratory Science
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• v.38 no.3
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• pp.184-188
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• 2006

The purpose of the recovery experiment in clinical chemistry is performed to estimate proportional systematic error. We must know all measurements have some error margin in measuring analytical performance. Proportional systematic error is the type of error whose magnitude increases as the concentration of analyte increases. This error is often caused by a substance in the sample matrix that reacts with the sought for analyte and therefore competes with the analytical reagent. Recovery experiments, therefore, are used rather selectively and do not have a high priority when another analytical method is available for comparison purposes. They may still be useful to help understand the nature of any bias revealed in the comparison of kit experiments. Recovery should be expressed as a percentage because the experimental objective is to estimate proportional systematic error, which is a percentage type of error. Good recovery is 100.0%. The difference between 100 and the observed recovery(in percent) is the proportional systematic error. We calculated the amount of analyte added by multiplying the concentration of the analyte added solution by the dilution factor(mL standard)/(mL standard + mL specimen) and took the difference between the sample with addition and the sample with dilution. When making judgments on method performance, the observed that the errors should be compared to the defined allowable error. The average recovery needs to be converted to proportional error(100%/Recovery) and then compared to an analytical quality requirement expressed in percent. The results of recovery experiments were total protein(101.4%), albumin(97.4%), total bilirubin(104%), alkaline phosphatase(89.1%), aspartate aminotransferase(102.8), alanine aminotransferase(103.2), gamma glutamyl transpeptidase(97.6%), creatine kinase(105.4%), lactate dehydrogenase(95.9%), creatinine(103.1%), blood urea nitrogen(102.9%), uric acid(106.4%), total cholesterol(108.5), triglycerides(89.6%), glucose(93%), amylase(109.8), calcium(102.8), inorganic phosphorus(106.3%). We then compared the observed error to the amount of error allowable for the test. There were no items beyond the CLIA criterion for acceptable performance.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.724-729
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• 2013

Simultaneous nitrification and denitrification (SND) occurs concurrently in the same reactor under micro dissolved oxygen (DO) conditions. Anaerobic zone was applied for phosphorus release prior to an aerated membrane bio-reactor (MBR), and anoxic zone was installed by placing a baffle in the MBR for enhancing denitrification even in high DO concentration in the MBR. Phosphorus removal was tested by alum coagulation in the anaerobic reactor preceding to MBR. DO concentration were 2.0, 1.5, 1.0, 0.75 mg/L in the MBR at different operating stages for finding optimum DO concentration in MBR for nitrogen removal by SND. pH was maintained at 7.0~8.0 without addition of alkaline solution even with alum addition due to high alkalinity in the raw sewage. Both TCODcr and $NH_4^+$-N removal efficiency were over 90% at all DO concentration. TN removal efficiencies were 50, 51, 54, 66% at DO concentration of 2.0, 1.5, 1.0, 0.75 mg/L, respectively. At DO concentration of 0.75 mg/L with addition of alum, TN removal efficiency decreased to 54%. TP removal efficiency increased from 29% to 95% by adding alum to anaerobic reactor. The period of chemical backwashing of the membrane module increased from 15~20 days to 40~50 days after addition of alum.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.261-267
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• 2011

ACKGROUND: Cadmium (Cd) has long been recognized as one of most toxic elements. Application of organic amendments and phosphate fertilizers can decrease the bioavailability of heavy metals in contaminated soil. METHODS AND RESULTS: This study was conducted to evaluate effect of combined application of phosphate fertilizer and manure in reducing cadmium phytoavailability in heavy metal contaminated soil. Phosphate fertilizers [Fused and super phosphate (FSP) and $K_2HPO_4$ (DPP)] and manure (M) were applied as single application (FSP, DPP, and M) to combined application (FSP+M and DPP+M) before radish seeding. $K_2HPO_4$ decreased $NH_4OAc$ extractable Cd and plant Cd concentration, mainly due to increases in soil pH and negative charge. However, FSP increased $NH_4OAc$ extractable Cd and plant Cd concentration. Manure significantly increased soil pH and negative charge. Combined application of phosphate fertilizer and manure were much more effective in reducing Cd phytoavailability than a simple application of each component. Calculated solubility diagram indicated that Cd concentrations in the solution of soils amended with phosphate fertilizers and manure were undersaturated with respect to all potential Cd minerals [$Cd_3(PO_4)_2$, $CdCO_3$, $Cd(OH)_2$, and $CdHPO_4$]. Plant Cd concentration and $NH_4OAc$ extractable Cd were negatively related to soil pH and negative charge. CONCLUSION: Alleviation of Cd phytoavailability with phosphate fertilizer and manure can be attributed primarily to Cd immobilization due to the increase in soil pH and negative charge rather than Cd and phosphate precipitation. Therefore, combined application of alkaline phosphate materials and manure is effective for reducing Cd phytoavailability.

• Resources Recycling
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• v.7 no.3
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• pp.3-10
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• 1998

Simulated waste liquid containing 50 ppm cobalt ion was treated by adsorbing colloidal flotation using Fe(III) or Al(IlI) as flocclant and a sodium lamyl sulfate as a collector. Parameters such as pH, surfactant concentration, Fe(III) or Al(III) concentration, gas flow rate, etc., W앙e considered. The flotation with Fe(III) showed 99.8% removal efficiency of cohalt on the conditions of initial cobalt ion concentration 50 ppm, pH 9.5, gas flow rate 70 ml/min, and flotation time 30 min. When the waste solution, was treated with 35% $H_2O_2$ prior to adsorbing colloidal flotation, the optimal pH for removing cobalt shifted m to weak alkaline range and flotation could be applied in wider range of pH as compared to non-use of $H_2O_2$. Additional use of 20 ppm Al(III) after precipitation of 50 ppm Co(II) with 50 ppm Fe(III) made the optimal pH range for preferable flotation w wider. Foreign ions such as, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $Ca^{2+}$ were adopted and their effects were observed. Of which sulfate ion was f found to be detrimental to removal of cob퍼t ion by flotation. Coprecipitation of Co ion with Fe(III) and Al(III) resulted in b better removal efficiency of cobalt IOn 피 the presence of sulfate ion.

• Journal of the Mineralogical Society of Korea
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• v.18 no.1
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• pp.1-9
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• 2005

The electrocatalytic reduction of O₂ was investigated with methyl viologen and methylene blue incorporated clay-modified electrodes. Clay suspensions were prepared with Na-montmorillonite, Ca-montmorillonite, and kaolinite. The methyl viologen-clay modified electrodes were made by coating clay suspensions adsorbing methyl viologen on a glassy carbon electrode. Cyclic voltammetry were performed in aqueous media to investigate the electrocatalytic property of the modified electrode in reducing O₂. A Na-montmorillonite modified electrode showed the greatest adsorption capacity for methyl viologen. The modified electrode made of Na-montmorillonite suspension of 0.87 g/10 mL and a 2.5 mM of methyl viologen solution showed the most effective electrocatalytic property, where the catalytic reduction potential was shifted by 242.6 mV toward the positive potential. The electrocatalytic ability was more significant in acidic (pH=3.7) and alkaline (pH=12.7) media than the neutral pH range (6.3∼8.3). The methyl viologen-Na-montmorillonite modified electrode had the good reproducibility and maintain the electrocatalytic property over 20 times reuse.

• Korean Journal of Materials Research
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• v.22 no.7
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• pp.379-383
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• 2012

$TiO_2$ thin films consisting of positively charged poly(diallyldimethylammonium chloride)(PDDA) and negatively charged titanium(IV) bis(ammonium lactato) dihydroxide(TALH) were successfully fabricated on glass beads by a layer-by-layer(LBL) self-assembly method. The glass beads used here showed a positive charge in an acid range and negative charge in an alkaline range. The glass beads coated with the coating sequence of(PDDA/TALH)n showed a change in the surface morphology as a function of the number of bilayers. When the number of bilayers(n) of the(PDDA/TALH) thin film was 20, Ti element was observed on the surface of the coated glass beads. The thin films coated onto the glass beads had a main peak of the (101) crystal face and were highly crystallized with XRD diffraction peaks of anatase-type $TiO_2$ according to an XRD analysis. In addition, the $TiO_2$ thin films showed photocatalytic properties such that they could decompose a methyl orange solution under illumination with UV light. As the number of bilayers of the(PDDA/TALH) thin film increased, the photocatalytic property of the $TiO_2$-coated glass beads increased with the increase in the thin film thickness. The surface morphologies and optical properties of glass beads coated with $TiO_2$ thin films with different coating numbers were measured by field emission scanning electron microscopy(FE-SEM), X-ray diffraction(XRD) and by UV-Vis spectrophotometry(UV-vis).

• Resources Recycling
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• v.13 no.4
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• pp.23-31
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• 2004

Basic studies have been conducted regarding the attempt of the utilization of waste Undaria pinnatifida as an adsorbent for the adsorption treatment of lead-containing wastewater. Undaria pinnatifida was found to be chiefly composed of hyo-carbonaceous compounds and have a fairly high specific surface area, which suggesting the possibility of its application as a Potential adsorbent. The electrokinetic Potential of Undaria pinnatifida particles was observed to be negatively highest at around pH 8 and the fact that its electrokinetic potentials are negative at the whole pH range supported it might be an efficient adsorbent especially for cationic adsorbates. Under the experimental conditions, $Pb^{2+}$ was found to mostly adsorb onto Undaria pinnatifida within a few minutes and reach the equilibrium in adsorption within ca. 30 minutes. The adsorption of $Pb^{2+}$ was exothermic and explained well by e Freundlich model. Acidic pretreatment of Undaria pinnatifida enhanced its adsorption capacity for $Pb^{2+}$ , however, the reverse was observed for alkaline pretreatment. The formation of organometallic complex between $Pb^{2+}$ and some functional groups on the surface of Undaria pinnatifida was considered to be one of the main drives for adsorption. Finally the adsorbability of$ Pb^{2+}$ was examined to be rather affected by several solution features such as the coexistence of other adsorbate, the variation of ionic strength, and the concentration of complexing agent.

• The Journal of Engineering Geology
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• v.31 no.1
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• pp.67-81
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• 2021

Grouting is used for reinforcement and waterproofing of soft ground to increase its bearing capacity, reduce the impacts of rising or lowering groundwater levels, and reduce subsidence due to vibration and general causes. This study investigated the enhancement of grout strength and hardening time by the addition of reinforcing fibers, and the development of non-cement grouting materials from blast furnace slag. An experiment was performed to measure the increase in grout strength resulting from the addition of 0.5% increments of aramid and carbon reinforcing fibers. The results show that the uniaxial compressive strength of grout increases with increasing content of reinforcing fiber. Comparison of three admixtures of finely powdered blast furnace slag and 10%, 20%, and 30% calcium hydroxide stimulating agent showed that the uniaxial compressive strength of the mixture increases with increasing content of alkaline stimulant; however, the strength was lower than for 100% pure cement. The reaction of calcium hydroxide with blast furnace slag powder, which increases the strength of the grout, is more effective if injected as a solution rather than a powder.

• Korean Journal of Veterinary Service
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• v.45 no.2
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• pp.117-124
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• 2022

In the event of an outbreak of a livestock epidemic, it has been considered that the existing burial-centered carcass disposal method should be improved ecofriendly for prevention of leachate and odors from burial basically in regard of pathogen inactivation. Therefore, the aim of this study is whether it was possible to treat the carcass of cattle and chickens using the chemical carcass treatment method. It was conducted to establish detailed treatment standards for the chemical treatment method of cattle and chicken carcasses based on the results of the proof of the absence of infectious diseases in cattle chickens. After inoculating cattle carcass with 10 pathogens (foot and mouth disease virus, bovine viral diarrhea virus, Mycobacterium bovis, Mycobacterium avium subsp. Paratuberculosis, Brucella abortus, Bacillus anthracis, Clostridium chauvoei, Clostridium perfringens, Escherichia coli, and Salmonella Typhimurium) and chicken carcasses with low pathogenic avian influenza virus, Clostridium perfringens type C, E. coli and Salmonella Typhimurium, these were treated at 90℃ for 5 hours in a potassium hydroxide liquid solution corresponding to 15% of the body weight. This method liquefies all cadaveric components and inactivates all inoculated pathogens by PCR and culture. Based on these results, it was possible to prove that chemical treatment of cattle and chicken carcasses is effective in killing pathogens and is a safe method without the risk of disease transmission. The chemical treatment method of livestock carcasses can be suggested as an alternative to the current domestic burial-centered livestock carcass treatment method, preventing environmental pollution, and contributing to public health.