• Journal of the Korean Chemical Society
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• v.51 no.2
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• pp.141-146
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• 2007

The present paper describes a procedure for separation, preconcentration and determination of trace amount of copper in natural water samples by using 2-mercaptobenzimidazol as the complexing agent. The proposed method is based on the surfactant aggregation formed on γ-alumina by mixing sodium dodecyl sulfate and γ-alumina in water; 2-mercaptobenzimidazol was incorporated into inner hydrophobic part of produced ad-micelles in acidic media to produce an assemble suitable for preconcentration and determination of copper ion. Optimum experimental conditions for adsorption of μg/ml levels of copper ions from aqueous solution by the adsorbent have been reported. The copper ions were quantitively adsorbed by the sorbent over the pH range of 7.1-8.0 and were quantitatively desorbed afterward by using sulfosalycilic acid as the eluent. The determination of copper was not interfered in the presence of common metal ions. The procedure was applied for analysis of river water sample. Relative standard deviation was found to be 4.91%.

• Journal of Preventive Medicine and Public Health
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• v.53 no.1
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• pp.29-36
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• 2020

Objectives: Prenatal cadmium (Cd) exposure may be associated with attention-deficit/hyperactivity disorder (ADHD) in children. Therefore, the objective of this study was to examine the relationship between Cd exposure during gestation and ADHD at 6 years of age. Methods: As part of an ongoing cohort study (the Environment and Development of Children study), 479 mother-child pairs from Seoul, Korea were included for analysis between 2008 and 2011. The whole blood concentration of Cd was analyzed using atomic absorption spectrophotometry. The parents were surveyed about ADHD behaviors in their children at age 6. Multivariable linear regression models were used to investigate the relationship between prenatal exposure to Cd and ADHD at 6 years of age. Results: Increased prenatal Cd concentrations were associated with increased scores for ADHD for girls, but not for boys, at age 6. A 2-fold increase in the prenatal Cd level was significantly associated with a 22.3% (95% confidence interval, 11.6 to 34.1) increase in ADHD in girls at 6 years of age, as indicated by the linear regression model. Conclusions: Our results identified significant associations between prenatal Cd exposure and ADHD scores in 6-year-old girls.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.136.1-136.1
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• 2015

In the present study, UHF (320 MHz) in combination with RF (13.56 MHz) plasmas was used for the synthesis of hydrogenated silicon nitride (SiNx:H) films by PECVD process at low temperature. RF/UHF hybrid plasmas were maintained at a fixed pressure of 410 mTorr in the N2/SiH4 and N2/SiH4/NH3 atmospheres. To investigate the radical generation and plasma formation and their control for the growth of the film, plasma diagnostic tools like vacuum ultraviolet absorption spectroscopy (VUVAS), optical emission spectroscopy (OES), and RF compensated Langmuir probe (LP) were utilized. Utilization of RF/UHF hybrid plasmas enables very high plasma densities ~ 1011 cm-3 with low electron temperature. Measurements using VUVAS reveal the UHF source is quite effective in the dissociation of the N2 gas to generate more active atomic N. It results in the enhancement of the Si-N bond concentration in the film. Consequently, the deposition rate has been significantly improved up to 2nm/s for the high rate synthesis of highly transparent (up to 90 %) SiNx:H film. The films properties such as optical transmittance and chemical composition are investigated using different analysis tools.

• Environmental Analysis Health and Toxicology
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• v.17 no.2
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• pp.109-115
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• 2002

This study was conducted to investigate the reference value of mercury (Hg) in liver and kidney of Korean population. The mercury concentration in 244‘sudden and unexpected death’autopsies (male: 180, female: 64) aged from 0 to 87 years was analyzed. The concentration of mercury was measured by atomic absorption spectrophotometer (Perkin-Elmer Model 5100) with mercury/hydride generating system (FIAS 400). The contents of mercury in liver and kidney fitted well the log-normal distribution rather than normal distribution. Geometric mean concentration of mercury in liver and kidney was 0.115 $\mu\textrm{g}$/g wet weight and 0.149 $\mu\textrm{g}$/g wet weight, respectively. Geometric mean concentration of mercury in female was higher than in male (p < 0.01). The mercury content in liver and kidney increased with age up to the forties and slightly decreased there-after. The regression model of mercury deposit in liver and kidney by age was predicted as the following equation : Log LHg : -1.0576＋0.0045$.$Age-0.0001$.$Age$^2$＋0.0873$.$Sex, Log KHg = -1.0576＋0.0152$.$Age-0.0002$.$Age$^2$＋0.1935$.$Sex. The liver burden of mercury was estimated to be 158.3∼161.3 $\mu\textrm{g}$ in male and 163.0∼166.9 $\mu\textrm{g}$ in female. The kidney burden of mercury was estimated to be 42.0∼42.9 $\mu\textrm{g}$ in male and 55.5∼57.1 $\mu\textrm{g}$ in female.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.38.2-38.2
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• 2013

Several studies have reported the presence of sodium excess objects having neutral atomic absorption lines at $5895{\AA}$ (NaD) and $8190{\AA}$ that are deeper than expected based on stellar population models that match the stellar continuum. The origin of these lines is therefore hotly debated. van Dokkum & Conroy proposed that low-mass stars (0.3M) are more prevalent in massive early-type galaxies, which may lead to a strong NaI 8190 line strength. It is necessary to test this prediction, however, against other prominent optical line indices such as NaD, Mgb, and Fe5270, which can be measured with a significantly higher signal-to-noise ratio than NaI 8190. We identified a new sample of roughly one thousand NaD excess objects (NEOs; ~8% of galaxies in the sample) based on NaD line strength in the redshift range 0.00${\alpha}$-enhanced" ([${\alpha}/Fe$] ~ 0.3), "metal-rich" ([Z/H] ~ 0.3), and, especially, "Na-enhanced" ([Na/Fe] ~ 0.3).

• Journal of The Korean Society of Grassland and Forage Science
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• v.40 no.3
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• pp.190-195
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• 2020

Cadmium (Cd) toxicity is a serious limitation for agricultural production. In this study, we explored tolerance mechanism associated with Cd toxicity tolerance in alfalfa plants. We used three distinct alfalfa cultivars M. sativa cv. Vernal, M. sativa cv. Zhung Mu, and M. sativa cv. Xing Jiang Daye in this study. Cd showed declined chlorophyll score in Xing Jiang Daye compared with Zhung Mu and Vernal. No significant change observed among the cultivars for root and shoot length. Atomic absorption spectroscopy analysis demonstrated a significant accumulation of Cd, Fe, S and PC in distinct alfalfa cultivars. However, Zhung Mu and Xing Jiang Daye declined Cd accumulation in root, where Fe, S and PC incremented only in Zhung Mu. It suggests that excess Cd in Zhung Mu possibly inhibited in root by the increased accumulation of Fe, S and PC. This was further confirmed by the response of Fe (MsIRT1) and S transporters (MsSULTR1;2 and MsSULTR1;3), and MsPCS1 genes associated with Fe, S and PC availability and translocation in roots and shoots. It suggests that specially the transcript signal inducing the responses to adjust Cd especially in Zhung Mu. This finding provides the essential background for further molecular breeding program for forage crops.

• Korean Journal of Food Science and Technology
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• v.36 no.4
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• pp.523-526
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• 2004

There are few studies on toxic metals in fruits. Therefore, we examined contents of toxic metals in fruits (n=386) available in Korean markets. The samples were digested with acids, then analyzed by inductively coupled plasma spectrometer (ICP) or atomic absorption spectrophotometer (AAS) for lead (Pb), cadmium (Cd), and arsenic (As). The contents of mercury (Hg) were also determined using a mercury analyzer, Contents of toxic metals in fruits were as follows [minimum-maximum (mean), mg/kg]; Hg 0.0001-0.019 (0.001), Pb 0.001-0.410 (0.013), Cd 0.001-0.035 (0.000), and As 0.001-0.210 (0.017). Our results showed that metal contents in fruits in Korean markets were similar to those reported in other countries. Average weekly intakes of Hg, Pb, and Cd from fruits are about 1-2% of Provisional Tolerable Weekly Intakes (PTWI) set by FAO/WHO Joint Food Additive and Contaminants Committee for safety evaluation.

• Korean Journal of Materials Research
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• v.26 no.4
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• pp.194-199
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• 2016

We prepared polymethyl methacrylate (PMMA) beads with a particle size of 80 nm to improve the energy conversion efficiency (ECE) by increasing the effective surface area and the dye absorption ability of the working electrodes (WEs) in a dye sensitized solar cell (DSSC). We prepared the $TiO_2$ layer with PMMA beads of 0.0~1.0 wt%; then, finally, a DSSC with $0.45cm^2$ active area was obtained. Optical microscopy, transmission electron microscopy, field emission scanning electron microscopy, and atomic force microscopy were used to characterize the microstructure of the $TiO_2$ layer with PMMA. UV-VIS-NIR was used to determine the optical absorbance of the WEs with PMMA. A solar simulator and a potentiostat were used to determine the photovoltaic properties of the PMMA-added DSSC. Analysis of the microstructure showed that pores of 200 nm were formed by the decomposition of PMMA. Also, root mean square values linearly increased as more PMMA was added. The absorbance in the visible light regime was found to increase as the degree of PMMA dispersion increased. The ECE increased from 4.91% to 5.35% when the amount of PMMA beads added was increased from 0.0 to 0.4 wt%. However, the ECE decreased when more than 0.6 wt% of PMMA was added. Thus, adding a proper amount of PMMA to the $TiO_2$ layer was determined to be an effective method for improving the ECE of a DSSC.

• Biomedical Science Letters
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• v.9 no.4
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• pp.223-229
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• 2003

The welding workers are frequently exposed to heavy metals such as manganese. Manganese is well evaporated into the air while welding. This study had been carried out to investigate the relationship of the blood manganese level to age, work duration, and smoking status among 128 welding workers in Gyeongnam and Jeonnam province from May to November, 2003. They showed high manganese level in the first health examination. Subjects were also classified for the investigation according to their smoking status as smokers and nonsmokers, work duration ($\leq$9, 10~9, 20$\leq$years), and ages ($\leq$29, 30~39, 40~49, 50$\leq$years). Blood manganese Jevels were analyzed by atomic absorption spectrophotometer (AAS). Mean blood manganese level was 1.62$\pm$0.56 $\mu\textrm{g}$/dl. In the comparison of blood manganese levels by age and smoking status, mean blood manganese levels of smokers in age of 20's, 30's, and 50's were 2.09$\pm$0.44 $\mu\textrm{g}$/dl, 1.94$\pm$0.33 $\mu\textrm{g}$/dl, and 2.l5$\pm$0.33 $\mu\textrm{g}$/dl, respectively. Blood manganese levels of smokers were significantly higher than those of non-smokers, showing no significant difference in the 40's. In the comparison of blood manganese levels by work duration, the blood manganese levels of smokers were the highest in the case of 10 to 19 years work duration. This study showed that the blood manganese levels were related to the smoking status, work duration, and age. Mean manganese levels of smokers showed higher than those of nonsmokers. It also showed that the length of work duration was related to the elevation of blood manganese levels. Among the welding workers, blood manganese levels of smokers were the highest over their age of 50's. In conclusion, smoking was the most significant risk factor to increase blood manganese levels. The further study will need analysis of the other factors related to manganese level elevation.

• Journal of Environmental Health Sciences
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• v.42 no.3
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• pp.205-212
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• 2016

Objectives: The objective of this study was to evaluate the distribution of blood lead concentrations of residents in the areas surrounding an industrial complex. Methods: During the three-month period from August to October 2012, informed consent was obtained from a total of 417 residents in Gwangyang and Yeosu. We collected blood samples from all subjects, and their demographic characteristics were acquired using a questionnaire. The blood samples were analyzed using an atomic absorption spectrometer and data analysis was conducted using IBM SPSS version 21.0. Results: The geometric mean concentration of blood lead in all subjects was $1.85{\mu}g/dL$. The highest (p<0.01) blood lead concentrations were in the current drinking group ($2.24{\mu}g/dL$). Blood lead concentrations in the smoking group ($0.59{\mu}g/dL$) were significantly (p<0.05) higher than those in the non-smoking group ($0.24{\mu}g/dL$). Risk assessment was performe using the Korean National Environmental Health Survey (KNEHS) as a reference. The hazard indices of blood lead in males and females were 0.65 and 0.52, respectively Conclusion: We provided baseline data for reference values of toxicity and heavy lead concentrations. Our results might be useful for further evaluation of risks due to exposure to heavy metals via oral, air, and percutaneous routes.