• Restorative Dentistry and Endodontics
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• v.35 no.4
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• pp.295-301
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• 2010

Recent studies demonstrated that the combination of chlorhexidine (CHX) and sodium hypochlorite (NaOCl) resulted in the formation of a precipitate, para-chloroaniline (PCA). Alexdidine (ALX) is a kind of biguanides like CHX, and has stronger detoxification effect against the bacterial virulence factors such as lipoteichoic acid and lipopolysacchardide compared with CHX. The purpose of this study was to determine whether PCA was formed after chemical interaction between ALX and NaOCl using mass spectrometry. Mass spectrometry was performed for the mixture of five different concentrations of ALX (1, 0.5, 0.25, 0.125, 0.0625%) and 4% NaOCl. Results showed that the peak of PCA was not detected in mixed solutions of ALX and NaOCl in mass spectrometry analysis. The color of mixed solution of ALX and NaOCl after chemical interaction was light yellow to white, but there wasn't any precipitate found.

• Membrane and Water Treatment
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• v.12 no.1
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• pp.1-9
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• 2021

This study optimized the chemical cleaning process of discarded RO membranes for reuse in less demanding separation processes. The effect of physicochemical parameters, including the temperature, cleaning time, pH of the cleaning solution, and addition of additives, on the cleaning process was investigated. The membrane performance was evaluated by testing the flux recovery rate and salt rejection before and after the cleaning process. High temperatures (45-50 ℃) resulted in a better flux recovery rate of 71% with more than 80% salt rejection. Equal time for acid and base cleaning 3-3 h presented a 72.43% flux recovery rate with salt rejection above 85%. During acid and base cleaning, the best results were achieved at pH values of 3.0 and 12.0, respectively. Moreover, 0.05% concentration of ethylenediaminetetraacetic acid presented 72.3% flux recovery, while 69.2% flux was achieved using sodium dodecyl sulfate with a concentration of 0.5%; both showed >80% salt rejection, indicating no damage to the active layer of the membrane. Conversely, 0.5% concentration of sodium percarbonate showed 83.1% flux recovery and 0.005% concentration of sodium hypochlorite presented 85.2% flux recovery, while a high concentration of these chemicals resulted in oxidation of the membrane that caused a reduction in salt rejection.

• Parasites, Hosts and Diseases
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• v.54 no.1
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• pp.103-107
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• 2016

The objective of this study was to evaluate the effects of several different commercial disinfectants on the embryogenic development of Ascaris suum eggs. A 1-ml aliquot of each disinfectant was mixed with approximately 40,000 decorticated or intact A. suum eggs in sterile tubes. After each treatment time (at 0.5, 1, 5, 10, 30, and 60 min), disinfectants were washed away, and egg suspensions were incubated at $25^{\circ}C$ in distilled water for development of larvae inside. At 3 weeks of incubation after exposure, ethanol, methanol, and chlorohexidin treatments did not affect the larval development of A. suum eggs, regardless of their concentration and treatment time. Among disinfectants tested in this study, 3% cresol, 0.2% sodium hypochlorite and 0.02% sodium hypochlorite delayed but not inactivated the embryonation of decorticated eggs at 3 weeks of incubation, because at 6 weeks of incubation, undeveloped eggs completed embryonation regardless of exposure time, except for 10% povidone iodine. When the albumin layer of A. suum eggs remained intact, however, even the 10% povidone iodine solution took at least 5 min to reasonably inactivate most eggs, but never completely kill them with even 60 min of exposure. This study demonstrated that the treatment of A. suum eggs with many commercially available disinfectants does not affect the embryonation. Although some disinfectants may delay or stop the embryonation of A. suum eggs, they can hardly kill them completely.

• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.95-103
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• 1992

The purpose of this study was to evaluate the effect of the dentin pretreatment on the marginal leakage of a glassionomer cement. 1n this study, 60 molars with sound and healthy crown portion were used. The dentin surface of these teeth were exposed and polished with 600 grit silicon carbide paper. Square - shaped cavities were prepared on the flattened dentin surfaces and these were divided into 4 groups according to the dentin pretreatment procedures. Group I : Dentin pretreatment with distilled water as a control group. Group II : Dentin pretreatment with 5% sodium hypochlorite solution. Group III : Dentin pretreatment with Ketac conditioner. Group IV : Dentin pretreatment with 40% polyacrylic acid. The degrees of dye penetration in the cavity walls were assessed using a stereoscope at ${\times}40$ magnification according to the maximum dye penetration. The results were analyzed by using Mann - Whitney U test. The results were as follows : 1. All groups showed varying depth of dye penetration. 2. Distilled water group showed the most severe marginal leakage when compared with the other groups(P<0.05). 3. 40% polyacrylic acid group showed the least amount of marginal leakage compared with the other groups (P<0.05). 4. There were significant differences between Goup I(distilled water) and Group IV (40% polyacrylic acid)(P<0.05), but there were no significant differences among Group I(distilled water), Group II(sodium hypochlorite), Group III(Ketac conditioner) (P>0.05).

• Membrane Journal
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• v.30 no.2
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• pp.138-148
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• 2020

The purpose of this study was to identify the cleaning efficiency of fouled multi-bore hollow fiber membranes after purification of contaminated water. The PSf (polysulfone) based hollow fiber membrane manufactured by Pure & B Tech Co., Ltd. Was used in this study. The antifouling characteristics during the water treatment were studied using bovine serum albumin (BSA) as a model compound and the chemical resistance was evaluated after long-term impregnation in sodium hypochlorite (NaOCl) solution and Citric acid to understand the long term stability of the membranes. Water permeability and mechanical strength of the membranes after prolonged chemical exposure was measured to observe the change in mechanical stability and long term performance of the membrane. moreover, the recovery efficiency was also evaluated after chemical enhanced backwashing of a membrane contaminated with bovine serum albumin. The PSf hollow fiber membrane exhibited excellent chemical resistance, and it was confirmed that the efficiency of sodium hypochlorite was high as a result of chemical enhanced backwashing.

• Restorative Dentistry and Endodontics
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• v.40 no.1
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• pp.50-57
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• 2015

Objectives: The usage of medicinal plants as natural antimicrobial agents has grown in many fields including dental medicine. The aim of this in vitro study was three-fold: (i) to determine the chemical compositions of the Ferula gummosa essential oil (FGEO), (ii) to compare the antimicrobial efficacy of the oil with sodium hypochlorite (NaOCl) and chlorhexidine (CHX), (iii) to assess the toxic behavior of FGEO in different concentrations compared to 5% NaOCl and 0.2% CHX. Materials and Methods: Gas chromatography/mass spectrometry (GC/MS) was used to determine the chemical compositions of the oil. The disk diffusion method and a broth micro-dilution susceptibility assay were exploited to assess the antimicrobial efficacy against Enterococcus faecalis, Staphylococcus aureus, Streptococcus mitis, and Candida albicans. The cytocompatibility of the FGEO was assessed on L929 fibroblasts, and compared to that of NaOCl and CHX. Results: Twenty-seven constituents were recognized in FGEO. The major component of the oil was ${\beta}$-pinene (51.83%). All three irrigants significantly inhibited the growth of all examined microorganisms compared to the negative control group. FGEO at $50{\mu}g/mL$ was effective in lower concentration against Enterococcus faecalis than 5% NaOCl and 0.2% CHX, and was also more potent than 0.2% CHX against Candida albicans and Staphylococcus aureus. FGEO was a cytocompatible solution, and had significantly lower toxicity compared to 5% NaOCl and 0.2% CHX. Conclusions: FGEO showed a promising biological potency as a root canal disinfectant. More investigations are required on the effectiveness of this oil on intracanal bacterial biofilms.

• Korean Journal of Food Science and Technology
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• v.50 no.2
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• pp.172-178
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• 2018

The sterilization rates were investigated to develop effective pretreatment methods of garlic and ginger using antimicrobial agents and blanching. Antibacterial components in chopped garlic and ginger, such as allicin, ginger, and shogaol, exhibited an antibacterial effect that reduced bacteria by a factor of $10^1(CFU/g)$. The total number of bacteria in garlic and ginger was decreased by $10^1(CFU/g)$ after individually soaking in 1% (w/w) citric acid, calcium oxide and 200 ppm sodium hypochlorite solution for 1 h, respectively. When chopped garlic and ginger were immersed in 1% (w/w) calcium oxide solution for 1 h, the bactericidal effect was increased by $10^4-fold$. Total cells with thermoduric bacteria exhibited a $10^3-10^4-fold$ reduction after heating for 30-40 s at $90-95^{\circ}C$. The combination of soaking in 200 ppm sodium hypochlorite solution and blanching at $95^{\circ}C$, 40 s showed $10^1-fold$ decrease in total number of cells compared to blanching in whole ginger.

• Resources Recycling
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• v.26 no.4
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• pp.88-94
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• 2017

The recovery of gold in cyclone type electrolytic cell was conducted from solution for stripping gold of PCB by cyanide. The electrolytic recovery behaviors of gold was investigated by reaction time and addition of electrolytic sodium hypochlorite (NaOCl) and gold plating additive (KG-120). Because the electrolysis generated NaOCl reacted with the cyanide in the leachate by alkaline chlorination, more than 99% of the cyanide was removed at a $NaOCl(g)/CN^-(g)$ ratio of 1.0. When NaOCl was added during the recovery of the gold from cyanide leachate in the cyclone electrolytic cell, the recovery of gold was 98% at the ratio of $NaOCl(g)/CN^-(g)$ from 0.5 to 2.5 in 480 minutes and decreased rapidly over the ratio of 3.0. Gold was recovered more than 99% by adding 1.5 and 4.5%(v/v) of KG-120 with NaOCl in 480 minutes. In particular, when the concentration of KG-120 was 3.5 and 4.5%(v/v), more than 96% of gold was recovered within 240 minutes and the initial recovery rate was relatively faster. The optimum concentration of KG-120 is 3.5%(v/v) considering the economic feasibility and efficiency.

• Journal of the Korean Wood Science and Technology
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• v.46 no.3
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• pp.221-230
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• 2018

The purpose of this study was to evaluate the effect of several chemical treatments to prevent photodegradation of wood veneer by external UV (Ultraviolet) light. Of woods, walnut veneer is selected as a raw material for this study since it is known as a luxurious wood with dark color giving an esthetic effect. Alcohol-benzene, hydrogen peroxide ($H_2O_2$) and sodium hypochlorite (NaClO) solution were used for investigate the effect on color stabilization. Despite the removal of the extractive compounds, which is known as a discoloration component, a significant color change of walnut wood veneer was observed. Meanwhile, the veneers treated by 20 and 30% $H_2O_2$ solution at $75^{\circ}C$ for 1 h also showed the no positive effect of color stability exposed to UV light although they have a bleaching effect on wood veneer. Besides, it was difficult to maintain the original color of walnut veneer due to the elution of the extractive compounds. On the other hands, the veneer treated by NaClO solution indicated the good performance on color stability despite of the intensive UV light test. However, when the concentration exceeds 3%, surface roughness and fiber damage occurred simultaneously. Therefore, the walnut species should be treated with proper concentration when sodium hypochlorite is applied to the veneer.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.106-113
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• 1994

Dental professions are considered high risk for contracting hepatitis infection. In Korea, many patients are hepatitis B virus carriers. HBV are most efficiently transmitted by blood. Root canal treatment, as in cases of acute pulpitis always accompanied by contaminated blood. Therefore it is absolutely necessary to use irrigation solutions having strong antiviral effect for prophylaxis both dental personnel and patients. The purpose of this study was to investigate the antiviral effect of seven root canal irrigation solutions by radioimmunometric test. The solutions were 5% sodium phyochlorite, 5% cresol, 2% glutaraldehyde, 3% hydrogen peroxide, 0.05% chlorohexidine, 10% iodine, and 70% isoprophyl alcohol. Each irrigation solutions was mixed with serum preparated from HBsAg positive patients and sera were diluted to 1:1. 1:4. 1:20 and 1:100. Percentage of radioactivity was assayed with AUK(Sorbin biomedica, Italy) and COBRA(Packwood Instrument company, USA). Sodium hypochlorite and glutaraldehyde showed most strong antivral activity against HBsAg. Isoprophyl alcohol had moderate antiviral effect and the effect and the effect was increased especially in 1:4 solution. Hydrogen peroxide exihibited very weak aintivral activity. Cresol, chlorohexidine, and iodine exhibited little antiviral activity.