• Tuberculosis and Respiratory Diseases
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• v.62 no.4
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• pp.270-275
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• 2007

The QuantiFERON-TB Gold assay and tuberculin skin test (TST) have been useful test for diagnosing latent tuberculosis infections (LTBI). However, there are few reports on the efficacy of the QuantiFERON-TB Gold assay and TST in evaluating the response after the treatment of LTBI. This study examined the changes in the TST and QuantiFERON-TB Gold assay before and after a treatment for latent tuberculosis in health care workers (HCWs) at a local tertiary hospital. Methods: A cohort of volunteers working as nurses and doctors who underwent a TST and QuantiFERON-TB Gold assay was established. The volunteers positive for the QuantiFERON-TB Gold assay had been treated with 3 months of isoniazid (INH) and rifampin (RFP). After completing treatment, the TST and QuantiFERON-TB Gold assay were repeated. Results: Of the 48 participants (14 doctors, 34 nurses, M: F=11:37, mean $age=29.9{\pm}5.5$ years, mean employment $period=74.9{\pm}64.3$ months), 19 (39.6%) tested positive to the TST (mean induration=$19.1{\pm}9.7mm$) and 8 (16.7%) were QuantiFERON-TB Gold assay. Among them, one had active pulmonary tuberculosis. Seven volunteers were consistently positive to both the TST and QuantiFERON-TB Gold assay after being medicated with INH and RFP for 3 months. Conclusion: TST and QuantiFERON-TB Gold assay are unsuitable for evaluating the treatment response of LTBI because they were consistently positive both before and after the anti-tuberculosis medication.

• Journal of the Mineralogical Society of Korea
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• v.32 no.2
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• pp.113-126
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• 2019

This study aimed to effectively dissolve sulfide minerals through microwave-nitric acid leaching of invisible gold concentrate and then recover gold from the solid-residue with fire assay. For the purposes, this study conducted microwave-nitric acid leaching experiments to examine nitric acid concentration, time of microwave leaching, and sample addition effect. As results of the experiments, this study discovered that the weight loss rate of solid-residue increased as nitric acid concentration and microwave leaching time increased while weight loss rate decreased as sample addition increased. In an XRD analysis with solid-residue, it was discovered that pyrite completely disappeared when the nitric acid concentrate was 6 M and the microwave leaching time was 18 minutes. When a fire assay was carried out with solid-residue, gold particles with more content were recovered as nitric acid concentration and microwave leaching time increased whereas gold particles with more gold content were recovered as the sample addition decreased.

• Tuberculosis and Respiratory Diseases
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• v.66 no.1
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• pp.13-19
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• 2009

Background: The interferon-gamma assay is reported to have high sensitivity and specificity for making the diagnosis of latent tuberculosis infection. The clinical usefulness of this essay for detecting active tuberculosis has not fully defined. We evaluated the diagnostic value of the commercial interferon-gamma assay kit (QuantiFERONTB GOLD) for patients with suspected tuberculosis. Methods: From January to August 2007, we recruited 52 patients with suspected tuberculosis infection. We performed chest X-ray, sputum smear, culture, PCR and the QuantiFERON-TB GOLD test. Pleural fluid analysis and pleural biopsy were also done for the patients with pleural effusion. Results: Of the 52 patients we studied, 30 patients had a positive QuantiFERON-TB GOLD test result. 35 patients were finally diagnosed with active tuberculosis: twenty-five with a positive QuantiFERON-TB GOLD test and 10 with a negative QuantiFERON-TB GOLD test. The sensitivity of the QuantiFERON-TB GOLD test was 71.4% and the specificity was 64.7%. The positive predictive value was 0.83 and the negative predictive value was 0.50. There was no significant difference of any of the clinical and laboratory characteristics between the two groups of patients except the C-reactive protein (CRP) level. The CRP level was 29.2${\pm}$27.3 mg/dL in the pulmonary tuberculosis patients with a positive QuantiFERON-TB GOLD test and 72.9${\pm}$67.9 mg/dL in the patients with a negative QuantiFERON-TB GOLD test (p<0.05). Conclusion: The sensitivity and specificity of the QuantiFERON-TB GOLD test were inadequate for making the diagnosis of active tuberculosis. We suggest that the QuantiFERON-TB GOLD test should not be used by itself to exclude the diagnosis of active tuberculosis. The relationship of the QuantiFERON-TB GOLD test and the CRP level in patients with TB would be further investigated.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1341-1344
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• 2012

• Journal of the Mineralogical Society of Korea
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• v.32 no.3
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• pp.185-200
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• 2019

This study aimed to liberate gold from invisible gold concentrate (Au = 1,840.00 g/t) through microwave nitric acid leaching experiments. For the purpose, this study conducted microwave-nitric acid leaching experiments and examined nitric acid concentration effect, microwave leaching time effect and sample addition effect. The results of the experiments were as follows: Au (gold) contents were not detected in all of the microwave leaching conditions. In the insoluble-residue, weight loss rate tended to decrease as the nitric acid concentration, microwave leaching time and sample addition increased. In an XRD analysis with solid-residue, it was suggested that gypsum and anglesite were formed due to dissolution of calcite and galena by nitric acid solution. When a fire assay was carried out with insoluble-residue, it was discovered that gold contents of the solid-residue were 1.3 (Au = 2,464.70 g/t) and 28.8 (52,952.80 g/t) times more than those of concentrate. But in the gold contents recovered, a severe gold nugget effect appeared. It is expected that the gold nugget effect will decrease if a sampling method of concentrate is improved in the microwave-nitric acid leaching experiments and filtering paper with smaller pore size is used for leaching solution and burned filter paper is used for sampling in lead-fire assay.

• Bulletin of the Korean Chemical Society
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• v.32 no.1
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• pp.329-331
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• 2011

• Economic and Environmental Geology
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• v.52 no.6
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• pp.595-604
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• 2019

The purpose of this study was simply to obtain gold through a microwave-nitric acid experiment of invisible gold concentrate with the use of filter paper. For the purpose, this study conducted a microwave-nitric acid leaching experiment and examined nitric acid concentration. As a result of the experiment, this study discovered that Fe, Te and Ag were completely leached in the leaching solution whereas Au was not determined in all of the nitric acid conditions. The leaching solution was filtered with three filter papers and then these filter papers were analyzed with SEM/EDS. As a result of the EDS analysis, Au was detected in all of the surface and cross-section of the 1st, 2nd and 3rd filter papers. As the three filter papers containing solid-residue were analysed in the lead-fire assay, gold particles were found in all of the nitric acid conditions. In the lead-fire assay, maximum gold(452.50g/t) was recovered when nitric acid concentration was 6M and microwave leaching time was 12mins.

• Economic and Environmental Geology
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• v.46 no.6
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• pp.477-484
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• 2013

In order to recover gold from iron-hydroxide in acid mine drainage, a lead-fire assay has been used. Acid mine drainage is generated from mining waste rocks, and iron-hydroxide precipitates from acid mine drainage, which severely contaminates the area surrounding the mine. Iron-hydroxide samples contain on average 520.29 mg/kg of Fe, 4,414.62 mg/kg sulfur, and 16.19 mg/kg Au. In an XRD analysis, quartz and goethite were observed along with the iron-hydroxide. Using a lead-fire assay, the recovery of pure gold was on average 0.174 g/ton from the iron-hydroxide, whereas the gold not recovered in the process was on average 1.37 mg/kg. This unrecovered gold was lost to the glass slag due to the galena and lead formation. The galena and lead in the glass slag was identified through XRD.

• Korean Journal of Environmental Biology
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• v.28 no.1
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• pp.8-13
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• 2010

This study aimed the role of gold nanoparticles (AuNP) in advanced glycation end-products (AGEs) induced migration and invasion in bovine retinal endothelial cells (BRECs). BRECs were isolated from the retina. Cell viability was confirmed by the MTT assay. In vitro wound migration assay was performed to investigate the migration of BRECs. In vitro tube formation was measured by on-gel system. Apoptosis induced by AuNP was confirmed by caspase-3 assay. AGE-bovine serum albumin (BSA) demonstrated increase of cell migration and proliferation in BRECs. In addition, AuNP regardless of the existence of AGE-BSA suppressed proliferation, migration, and angiogenesis. AuNP suppressed AGE-BSA induced migration and invasion, and induced apoptosis through caspase-3. As a results, AuNP have a potential anti-angiogenic effect for AGE-induced angiogenesis in vitro and offer possibility for the treatment of diabetic retinopathy.

• Journal of the Korean Chemical Society
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• v.7 no.2
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• pp.165-169
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• 1963

12 samples from an assay process chain were submitted to qualitative and quantitative neutron activation analysis for the determination of gold. Gold was detected and quantitatively determined in three samples after a chemical separation consisting of solvent extraction and precipitation steps. Recoveries ranged between 81.0 and 93.6% and results of duplicated determinations were reproducible. Quantitative data were obtained from gamma-spectrometric photopeak-area counting. Interference from fast neutron reactions was negligible.