• Journal of Radiation Protection and Research
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• v.45 no.3
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• pp.142-146
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• 2020

Background: Tritium (³H) analysis in groundwater was difficult because of its low activity. Therefore, the electrolytic enrichment method was used. To improve the detection limit and for performing simple analysis, a high-volume counting vial with the available liquid scintillation counter (LSC) was investigated. Further, it was compared with a conventional 20-mL counting vial. Materials and Methods: The LSC with the electrolytic enrichment method was used ³H analysis in groundwater. A high-volume 145-mL counting vial was compared with a conventional 20-mL counting vial to determine the counting characteristics of different LSCs. Results and Discussion: When a Quantulus LSC was used, the counting window between channels 35 and 250 was used. The background count was approximately 1.86 cpm, and the counting efficiency increased from 8% to 40% depending on the mixing ratio of the volume of sample and cocktail solution. For LSC-LB7, the optimum counting window was between 1 and 4.9 keV, which was selected by the factory (Hitachi Aloka Medical Ltd., Japan) by considering quenching using a standard external gamma source. The background count of LSC-LB7 was approximately 3.60 ± 0.29 cpm when the 145-mL vial was used and 2.22 ± 0.17 cpm when the 20-mL vial was used. The minimum detectable activity (MDA) of the 20-mL vial was greater for LSC-LB7 than for Quantulus. The MDA with the 145-mL vial was improved to 0.3 Bq/L when compared with the value of 1.6 Bq/L for the 20-mL vial. Conclusion: The counting efficiency when using the 145-mL vial was 27%, whereas it was 18% when using the 20-mL vial. This difference can be attributed to the vial volume. The figure of merit (FOM) of the 145-mL vial was four times greater than that of the 20-mL vial because the volume of the former vial is approximately seven times greater than that of the latter. Further, the MDA for ³H decreased from 1.6 to 0.3 Bq/L. The counting efficiency and FOM of LSC-LB7 was slightly less than those of Quantulus when the 20-mL vial was used. The background counting rate of the Quantulus was lower than that of the LSC-LB7.

• Analytical Science and Technology
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• v.33 no.6
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• pp.274-284
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• 2020

This study described the analytical method for simultaneous determination of 89Sr and 90Sr in liquid sample using automated separation system. Radiostrontium in 0.5 kg of liquid sample was concentrated as SrCO3 to reduce the volume of sample, and purified from the sample using Sr-resin 2 mL (BV, Bed volume). The behavior of Sr and interferences such as Ba, Ca and Y were estimated with various flow rate ranging from 1 to 4 mL min-1. The detailed procedure for the purification of Sr on Sr-resin was presented. The purified radiostronitum was measured in Cerenkov mode and then measured in Scintillation mode by mixing scintillation cocktail. The measured value in both modes were used to calculate the activity of 89Sr and 90Sr. The performance tests were carried out the lab-control-sample having various activity ratio of between 89Sr and 90Sr. The recovery of Sr was ranged from 68 to 94 %. The relative bias of 89Sr activity was ranged from -5 to 20 %, and it was ranged from -10 to 10 % for 90Sr.

• Journal of Food Hygiene and Safety
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• v.18 no.4
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• pp.229-236
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• 2003

The five different foodborne pathogenic bacterial genera of Escherichi, Salmonella, Shigella, Vibrio and Listeria are important sources of foodpoison. However, the method was not developed to simultaneously differentiate these five bacteria at molecular level. The optimized concentrations of the four major PCR cocktail components of $MgCl_2$, dNTPs, primers and template DNA were determined when ERIC (enterobacterial repetitive intergenic consensus)-PCR reactions were carried out to differentiate the five differnet foodborne pathogenic bacteria. The optimized concentration of $MgCl_2$ was determined to be 2 mM in order to obtain a consistent fingerprinitng pattern. The similar fingerprinting pattern was obtained when ERIC primers and dNTPs were added up to the concentrations of 2 ${\mu}M$ and 200 ${\mu}M$, respectively. As for template DNA, the numbers of PCR fragments were not affected, but their intensities were increased as the concentrations of the DNA were increased.

• Journal of the Korean Wood Science and Technology
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• v.39 no.1
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• pp.95-103
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• 2011

We have investigated pretreatment of waste wood using milling refinery combined with poping method, which can save energy for pretreatment and enzyme loading for enzymatic hydrolysis. The chemical analysis of holocellulose of non and popping treated waste wood showed 65.9% and 58.8%, and the lignin, organic extracts and ash were increased by 3%, 4% and 0.7% after pretreatment, respectively. The reducing sugar yields of pretreated waste wood were increased four times more than non-pretreated one and the synergistic effect of cellulase and xylanase were evaluated compare with individual enzyme treatment. Especially, enzyme cocktail (cellulase 50 U and xylanase 50 U) treatment was very efficient in 1% substrate (50 mg). Also, glucose and xylose conversion rate of pretreated waste wood by GC analysis were 45.9% and 38.7%, respectively.

• Journal of Radiation Protection and Research
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• v.41 no.4
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• pp.395-401
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• 2016

Background: Liquid scintillation counters (LSCs) are commonly used as an analytical method for detecting $^{222}Rn$ in groundwater because they involve a simple sample pretreatment and allow high throughout with an autosampler. The Quantulus 1220 is the best-selling LSC in Korea, but its production was stopped. Recently, a new type of LSC, the 300SL, was introduced. In this study, the 300SL was compared with the Quantulus 1220 in order to evaluate the ability of each apparatus to detect $^{222}Rn$ in groundwater. Materials and Methods: The Quantulus 1220 and 300SL were used to detect the presence of $^{222}Rn$. Radon gas was extracted from a groundwater sample using a water-immiscible cocktail in a LSC vial. The optimal analytical conditions for each LSC were determined using a $^{222}Rn$ calibration source prepared with a $^{226}Ra$ source. Results and Discussion: The optimal pulse shape analysis level for alpha and beta separation was 80 for the Quantulus 1220, and the corresponding pulse length index was 12 in the 300SL. The counting efficiency of the Quantulus 1220 for alpha emissions was similar to that of the 300SL, but the background count rate of the Quantulus 1220 was 10 times lower than that of the 300SL. The minimum detectable activity of the Quantulus 1220 was $0.08Bq{\cdot}L^{-1}$, while that of the 300SL was $0.20Bq{\cdot}L^{-1}$. The analytical results regarding $^{222}Rn$ in groundwater were less than 10% different between these LSCs. Conclusion: The 300SL is an LSC that is comparable to the Quantulus 1220 for detecting $^{222}Rn$ in groundwater. Both LSCs can be applied to determine the levels of $^{222}Rn$ in groundwater under the management of the Ministry of Environment.

• Tuberculosis and Respiratory Diseases
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• v.47 no.6
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• pp.757-767
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• 1999

Background: Diagnosis by smear and/or cultures of the Mycobacterium tuberculosis from body fluid or biopsy specimen is "Gold standard". However the sensitivity of the direct microscopy is relatively low and culture of mycobacteria is time consuming. Despite an explosion in the techniques of rapid identification of mycobacteria by molecular genetic means, it is laborious and expensive and then rapid, inexpensive serodiagnosis is interested in diagnosis of tuberculosis. But sensitivity and specificity of known serologic antigen is not full sufficient level and then new antigen develop and combination cocktails of new developed antigens by ELISA are needed. Method: To compare the efficacy of different mycobacterial specific antigen and to assess the applicability of the combination of several different antigens in the diagnosis of tuberculosis, five ELISA tests derived 14KDa, 16KDa, 19KDa, 23KDa, 38KDa were evaluated in 57 active pulmonary patient and 24 inactive post-therapy follow up patient and 48 normal control. Results: The optical densities of ELISA test with 14KDa, 16KDa, 19KDa, 23KDa, 38KDa were significantly higher in active tuberculosis cases than in normal control(P<0.001, P<0.001, P<0.027, P<0.001, P<0.001) and those with 16KDa, 38KDa were significant higher in active tuberculosis cases than in inactive post-therapy follow up cases(P<0.01. P<0.001) and those of 14KDa, 16KDa, 23KDa, 38KDa were significant higher in inactive post-therapy follow up cases than in normal control(P<0.008. P<0.01. P<0.006. P<0.001). The sensitivity of 14KDa, 16KDa, 19KDa, 23KDa, 38KDa in active pulmonary patient cases was 42.1%, 43.9%, 15.8%, 28.0%, 70.2%, respectively and the specificity of 14KDa, 16KDa, 19KDa, 23KDa, 38KDa in active pulmonary patient cases was 95.8%, 95.8%, 91.7%, 89.6%, 93.8%, respectively. The sensitivity and specificity of combination 38KDa with 16KDa was 87% and 93.7%. Conclusion: The sensitivity and specificity of new antigens for serodiagnosis of the tuberculosis still remains limited at around 70%, which makes its a poor diagnostic tool for disease confirmation. A combination of cocktail antigens provided by cut-off value adjustment for serodiagnosis of tuberculosis some improved diagnostic yield than single antigen serologic test.

• Journal of Food Hygiene and Safety
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• v.38 no.1
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• pp.31-36
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• 2023

This study was conducted to evaluate the efficacy of sodium hypochlorite in eliminating Escherichia coli strains from leafy green and stem vegetables, which are frequently sold at community service centers. A cocktail of non-pathogenic E. coli and enterohaemorrhagic E. coli (E. coli O157:H7) was used to artificially contaminate the vegetables (initial numbers of bacteria 7-8 log CFU/g). The contaminated vegetables were soaked in sodium hypochlorite for 5 min and then washed three times with running water. After the treatment, number of viable bacterial cells on the vegetables was estimated. Sodium hypochlorite treatment reduced the E. coli population by 1-2 log CFU/g on leafy green and stem vegetables, a significant reduction from the initial number. Further, sodium hypochlorite showed better antimicrobial efficacy for leaves with a larger surface area, less roughness, and softness. There was no significant difference in the antimicrobial effect between 100 and 200 mg/kg of sodium hypochlorite. Therefore, it is not necessary to increase sodium hypochlorite concentration than the level suggested in the school meal hygiene management guidelines. However, sodium hypochlorite treatment is not sufficient to achieve a safe level of microorganisms on leafy green and stem vegetables since they generally have a high abundance of microorganisms on their surface. Thus, an alternative cooking method for fresh leafy green and stem vegetables in summer should be developed to ensure they are safe for consumption.

• Journal of Plant Biotechnology
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• v.43 no.1
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• pp.91-98
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• 2016

The growth area of living modified (LM) cotton has steadily increased every year, since its first commercialization in 1996. Development of environmental risk assessment tools and techniques for LM cotton is required for ecosystem safety. We therefore developed multiplex PCR assays for simultaneous detection of two (MON15985, MON531) and four (GHB614, LLCOTTON25, MON88913 and MON1445) LM cotton events approved in Korea, with event specific primer pairs. The PCR reactions were optimized by using event specific primers of six LM cottons at various concentrations. The reactions allows amplification of estimated amplicons of MON15985 (214 bp), MON531 (270 bp), GHB614 (119 bp), LLCOTTON25 (164 bp), MON88913 (276 bp), and MON1445 (389 bp) from multiplex PCR reactions. The multiplex PCR assay developed allowed that two annealing steps (15 cycles at $55^{\circ}C$ and 25 cycles at $60^{\circ}C$) were performed for amplification of distinguished two LM cottons, and only one annealing step (50 cycles at $60^{\circ}C$) was necessary for tetraplex PCR. Primer extension step of all PCR reactions was skipped for time-effective amplification. Our methods suggest that two multiplex PCR assays can be cost-effective and a rapid diagnostic tool for environmental LMO monitoring of six LM cottons.