• The Journal of Advanced Prosthodontics
• /
• v.4 no.1
• /
• pp.24-29
• /
• 2012

PURPOSE. To compare the effect of sodium hypochlorite and microwave disinfection on the dimensional stability of denture bases without and with relining. MATERIALS AND METHODS. A brass die was prepared by simulating an edentulous maxillary arch. It was used to fabricate 1.5 mm and 3 mm of thickness denture bases (n = 40). The 1.5 mm of thickness-specimens (n = 20) were relined with 1.5 mm of autopolymerizing relining resin. Five holes were prepared over crest of ridge of brass die with intimately fitting stainless steel pins which were transferred to the intaglio surface of specimens during fabrication of denture bases. For calculation of dimensional changes in denture bases, differences between the baseline area before and after disinfection of the specimens were used. The denture bases without and with relining were divided into 2 groups (each n =20). Data were analyzed using student paired 't'and unpaired 't'test. RESULTS. Microwave disinfection produces significant shrinkage in both denture bases without relining (t =17.16; P<.001) and with relining (t = 14.9; P<.001). Denture bases without relining showed more shrinkage when compared with relined denture bases after microwave disinfection (t = 6.09; P<.001). The changes in dimensional stability after sodium hypochlorite disinfection were not significant for both denture bases without relining (t = 2.19; P=.056) and denture bases with relining (t = 2.17; P=.058). CONCLUSION. Microwave disinfection leads to increased shrinkage of denture bases without and with relining. Chemical disinfection with sodium hypochlorite seems to be a safer method of disinfection with regards to physical properties such as changes in dimensional stability.

• Journal of Environmental Science International
• /
• v.11 no.5
• /
• pp.411-418
• /
• 2002

The current study evaluated the disinfection efficiency of free chlorine and chloramine for microorganisms on various pipe materials, such as copper, galvanized steel, carbon steel, and stainless steel. In addition, the effect of internal pipe corrosion and corrosion inhibitors on the bactericidal efficiency was evaluated using a simulated loop. For disinfection with a phosphate corrosion inhibitor, chloramination was found to be more effective than chlorination due to its persistence. Free chlorine disinfection was optimized with a high phosphoric acid concentration, while chloramine disinfection was optimized with a high phosphoric acid or low polyphosphate concentration. In simulated copper and galvanized steel loop tests, chloramination with phosphoric acid was demonstrated to be more effective.

• Journal of Industrial Technology
• /
• v.27 no.A
• /
• pp.15-18
• /
• 2007

This study investigated disinfection effect by general water purifier and water purifier with UV light disinfection. The results are as follows : (i) The general bacteria existed plentifully in a storage tank before treatment (ii) Water treated in water purifier did not meet the water treatment regulation standard since the presence of bacteria, whereas with UV light application the regulation standard is totally satisfied. (iii) Photocatalytic disinfection process with UV light in the presence of $TiO_2$ more effectively killed general bacteria than UV light only.

• Journal of Environmental Science International
• /
• v.13 no.1
• /
• pp.55-59
• /
• 2004

The effect of ozone on the formation and the removal of disinfection byproducts(DBPs) of chlorination process was studied to elucidate the performance of water treatment process. The samples of raw water, prechlorination process, and preozonation process were analyzed quantitatively according to the Standard Methods for the Examination of drinking water. As a result, most of total trihalomethanes(THMs) which were formed in prechlorine treatment process was not removed in the preozonation process. Most of haloacetic acids(HAAs), haloacetonitriles(HANs), and chloral hydrate(CH) was removed in sedimentation and biological activated carbon(BAC) filtration processes. However, DBPs were increased more or less by postchlorine step. In particular, the formation of THMs and HAAs depends on ozone more than chlorine, but, the formation of HANs and CH depends on chlorine more than ozone. The seasonal variation of DBPs concentration for the year needs to be investigated to study the temperature effect because DBPs strongly depend on temperature among various efficient factors.

• Journal of fish pathology
• /
• v.28 no.3
• /
• pp.125-131
• /
• 2015

This study was performed to determine the disinfection efficacy of influent seawater by application of mechanical filtration and UV disinfection system (MFUVDS) in decreasing disease outbreak of juvenile olive flounder (Paralichthys olivaceus). Bacterial disinfection rate of influent seawater following the MFUVDS application was 99.27%. Mortalities of the juvenile reared for 4 months were 20~30% lower than those of the control (25.8%~34.9%).

• The Journal of Advanced Prosthodontics
• /
• v.14 no.5
• /
• pp.273-284
• /
• 2022

PURPOSE. Computer-aided design and manufacturing (CAD-CAM) of implant abutments has been shown to result in surface contamination from site-specific milling and fabrication processes. If not removed, these contaminants can have a potentially adverse effect and may trigger inflammatory responses of the peri-implant tissues. The aim of the present study was to evaluate the bacterial disinfection and cleaning efficacy of ultrasonic reprocessing in approved disinfectants to reduce the microbial load of CAD-CAM abutments. MATERIALS AND METHODS. Four different types of custom implant abutments (total N = 32) with eight specimens in each test group (type I to IV) were CAD-CAM manufactured. In two separate contamination experiments, specimens were contaminated with heparinized sheep blood alone and with heparinized sheep blood and the test bacterium Enterococcus faecium. Abutments in the test group were processed according to a three-stage ultrasonic protocol and assessed qualitatively and quantitatively by determination of residual protein. Ultrasonicated specimens contaminated with sheep blood and E. faecium were additionally eluted and the dilutions were incubated on agar plates for seven days. The determined bacterial counts were expressed as colony-forming units (CFU). RESULTS. Ultrasonic reprocessing resulted in a substantial decrease in residual bacterial protein to less than 80 ㎍ and a reduction in microbiota of more than 7 log levels of CFU for all abutment types, exceeding the effect required for disinfection. CONCLUSION. A three-stage ultrasonic cleaning and disinfection protocol results in effective bacterial decontamination. The procedure is reproducible and complies with the standardized reprocessing and disinfection specifications for one- or two-piece CAD-CAM implant abutments.

• Journal of Environmental Science International
• /
• v.15 no.7
• /
• pp.677-688
• /
• 2006

Currently, the application of $TiO_2$ photocatalyst has been focused on purification and treatment of wastewater. However, the use of conventional $TiO_2$ slurry photocatalyst results in disadvantage of stirring during the reaction and of separation after the reaction. And the usage of artificial UV lamp has made the cost of photocatalyst treatment system high. Consequently, we studied that solar light/$TiO_2$ film system was designed and developed in order to examine disinfection characteristics of sewage wastewater treatment. The optimum conditions for disinfection such as solar light intensity, characteristic of sewage wastewater, amounts of $TiO_2$ and comparison of solar ligth/$TiO_2$ systems with UV light/$TiO_2$ system was examined. The results are as follows: (1) photocatalytic disinfection process with solar light in the presence of $TiO_2$ film more effectively killed total coliform (TC) than solar light or $TiO_2$ film absorption only. (2) The survival ratio of TC and residual ratio of organic material (BOD, CODcr) decreased with remain resistant material. (3) The survival ratio of TC and residual ratio of organic material (BOD, CODcr) decreased with the increase of amounts of $TiO_2$. (4) TC survival ratio decreased linearly with increasing UV light intensity. (5) The disinfection effect of solar light/$TiO_2$ slurry system decreased more than UV light/$TiO_2$ film systems. (6) The disinfection reaction followed first-order kinetics. We suggest that solar light instead of using artificial UV light was conducted to investigate the applicability of alternative energy source in the disinfection of TC and the degradation of organic material.

• Journal of Korean Society of Environmental Engineers
• /
• v.29 no.1
• /
• pp.31-39
• /
• 2007

The objective of this study was to investigate the inactivation characteristics of Cryptosporidium oocysts by ozone and UV and to suggest the better, disinfection method. The inactivation CT value of 1 log(90%) and 2 log(99%) in of one disinfection, which is an index of disinfection for inactivation effect by ozone, were respectively 5.77 $mg{\cdot}min/L$ and 21.30 $mg{\cdot}min/L$. The inactivation in UV disinfection was not affected by pHs(5, 7 and 9), low turbidity(5 and below NTU) and UV intensity(0.2 and 0.6 $mWs/cm^2$) but obviously decreased at high turbidity over 20 NTU. Therefore UV disinfection capacity can be obtained when a good turbidity removal in drinking water treatment process is achieved. And if oocysts is exposed by high UV over 0.6 mWs/cm2 during enough time, the better inactivation effect will be obtained.

• Journal of Korean Biological Nursing Science
• /
• v.3 no.2
• /
• pp.1-20
• /
• 2001

The object of this study was to measure the biocidal effect of povidone on staphylococcus found in tracheal incision site, change following the disinfection frequency and duration, and tolerance to the antibiotics. The data was analysed by percentage and t-test using SAS program. The subjects of this study are 35 tracheostomy patients in and Intensive Care Unite of the hospital located in Daegu city and analysing term was from January 16 to February 26, 2001. The results of this study were as follows. The biocidal effect of povidone on Staphylococcus was strong regardless of time and concentration. Staphylococcus aureus was found on third day and found to be highest concentration on 6th day after disinfection of once/a day. Coagulase negative Staphylococcus was not found from 1st to 3rd day and highest on 4th day after disinfection of once/a day. As to bacteria colonization following the disinfection frequency, twice per day of disinfection was more effective on Staphylococcus aureus than once a day. In tolerance test of Staphylococcus aureus and Coagulase negative Staphylococcus, 72.7% of Staphylococcus aureus showed tolerance in Methicillin, 63.6% in Imipenem, and 37.5% of Coagulase negative Staphylococcus showed tolerance in Methicillin, 12.5% in Imipenem. Both of them do not have any tolerance in Vancomycin. The results of this study can be used as the basis for protection against hospital mediated infection through thorough disinfection. With above results, I suggest the following. First, we should research relation between antiseptics and fungi, virus more deeply. Secondly, all medical personnel should try to protect against the hospital medicated infection. Thirdly, there is a need of training professional disinfection personnel for preventing hospital mediated infection and the progress of nursing science.

• Journal of Korean Ophthalmic Optics Society
• /
• v.19 no.1
• /
• pp.59-67
• /
• 2014

Purpose: The present study was aimed to compare the results of disinfection efficacy tested by membrane filtration method with dilution-neutralization method to develop the standard methods for evaluating disinfection efficacy of contact lens care products and to provide the result of disinfection efficacy of commercially available contact lens care products in domestic market. Methods: The results of disinfection efficacy against Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens, Candida albicans evaluated by membrane filtration method as a FDA standard and dilution-neutralization method as newly being a KFDA standard were compared and the disinfection efficacy of 16 multi-purpose solutions was further evaluated. Results: The disinfectants and contact lens care products having strong disinfection efficacy showed same results in both membrane filtration method and dilution-neutralization method. In case of contact lens care products having weak disinfection efficacy, the number of micro-organisms was not able to count since the colony was aggregated when evaluated by membrane filtration method. However, the number of micro-organisms was able to exactly count when evaluated by dilution-neutralization method. In addition, some commercially available contact lens care products did not meet disinfection standard and especially, their disinfection effect was often weak against Serratia marcescen and Candida albicans. Conclusions: It is concluded that dilution-neutralization method will be useful to evaluate disinfection efficacy since it is possible to count micro-organisms more precisely even with small amount of sample and check the results faster compared with membrane filtration method.