• Korean Journal of Environmental Agriculture
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• v.36 no.1
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• pp.43-49
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• 2017

BACKGROUND: Greenhouse crops are one of agricultural products consumed largely in Korea. Cucumber is a typical example as main vegetables of greenhouse crops. Thus, pesticide residue analysis is an important requirement to guarantee pesticide safety of cucumber. This work was aim to investigate the residues of penthiopyrad and pyriofenone in cucumber after harvest. METHODS AND RESULTS: Cucumber was subjected to treat with penthiopyrad and pyriofenone at a level of recommended dose 0, 1, 2, 3, 5, 7 and 10 days before harvest under greenhouse conditions. The samples were extracted with organic solvent by using a homogenizer and purified on solid phase cartridge column followed by LC-MS/MS analysis. The recovery levels of penthiopyrad and pyriofenoneranged from approximately 81 to 93% with the method limit of 0.005 mg/kg and coefficient of variation less than 10%. Penthiopyrad and pyriofenone were detected at a level less than maximum residue limit in cucumber at 10 days before. The half-lives of penthiopyrad and pyriofenone were determined to 2.4 ~ 2.6 days. CONCLUSION: Penthiopyrad and pyriofenone are suggested to use in cucumber 10 days before harvest to reach their levels less than maximum residue limit.

• Economic and Environmental Geology
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• v.50 no.5
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• pp.341-352
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• 2017

Along with Cs-137 (half-life: 30.17 years), Sr-90 (half-life: 28.8 years) is one of the most important environmental monitoring radioactive elements. Rapid and easy monitoring method for Sr-90 using Laser-Induced Breakdown Spectroscopy (LIBS) has been studied. Strontium belongs to a bivalent alkaline earth metal such as calcium and has similar electron arrangement and size. Due to these similar chemical properties, it can easily enter into the human body through the food chain via water, soil, and crops when leaked into the environment. In addition, it is immersed into the bone at the case of human influx and causes the toxicity for a long time (biological half-life: about 50 years). It is a very reductive and related with the specific reaction that makes wet analysis difficult. In particular, radioactive strontium should be monitored by nuclear power plants but it is very difficult to be analysed from high-cost problems as well as low accuracy of analysis due to complicated analysis procedures, expensive analysis equipment, and a pretreatment process of using massive chemicals. Therefore, we introduce the Laser-Induced Breakdown Spectroscopy (LIBS) analysis method that analyzes the elements in the sample using the inherent spectrum by generating plasma on the sample using pulse energy, and it can be analyzed in a few seconds without preprocessing. A variety of analytical plates for samples were developed to improve the analytical sensitivity by optimizing the laser, wavelength, and time resolution. This can be effectively applied to real-time monitoring of radioactive wastewater discharged from a nuclear power plant, and furthermore, it can be applied as an emergency monitoring means such as possible future accidents at a nuclear power plants.

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.3
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• pp.275-280
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• 1995

The effect of supplemented high protein diet intake on renal urea regulation in swamp buffalo was carried out in the present experiment Five swamp buffalo heifers weighing between 208-284 kg were used for this study. The animals were fed with a supplementary high protein diet and renal function and kinetic parameters for urea excretion were measured. This was compared to a control period where the same animals had been fed only with paragrass and water hyacinth. For 2 months the same animals were fed a mixed of paragrass, water hyacinth plus 2 kgs of a high protein supplement (protein 18.2% DM basis) per head per day. In comparison to the control period, there were no differences in the rate of urine flow, glomerular filtration rate (GFR), effective renal plasma flow (ERPF), plasma urea concentration and filtered urea. In animals supplemented with high protein intake mean values of urea clearance, excretion rate and the urea urine/plasma concentration ratio markedly increased (p < 0.05) while renal urea reabsorption significantly decreased from 40% to 26% of the quantity filtered. In this same study group urea space distribution and urea pool size increased which coincided with an increase in plasma volume (p < 0.05). Plasma protein decreased while plasma osmolarity increased (p < 0.05). Both urea turnover rate and biological half-life of $^{14}C$-urea were not affected by a supplementary high protein intake. The results suggest that animals supplemented with high protein diets are in a state of dynamic equilibrium of urea which is well balanced between urea excreted into the urine and the amount synthesized. The limitation for renal tubular urea reabsorption would be a change in extra-renal factors with an elevation of the total pool size of nitrogenous substance.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.189-189
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• 2016

Recently, many researchers have shown an increased interest in colloidal quantum dots (QDs) due to their unique physical and optical properties of size control for energy band gap, narrow emission with small full width at half maxima (FWHM), broad spectral photo response from ultraviolet to infrared, and flexible solution processing. QDs can be widely used in the field of optoelectronic and biological applications and, in particular, colloidal QDs based light emitting diodes (QDLEDs) have attracted considerable attention as an emerging technology for next generation displays and solid state lighting. A few methods have been proposed to fabricate white color QDLEDs. However, the fabrication of white color QDLEDs using single QD is very challenging. Recently, hybrid nanocomposites consisting of CdTe/ZnO heterostructures were reported by Zhimin Yuan et al.[1] Here, we demonstrate a novel but facile technique for the synthesis of CdTe/ZnO/G.O(graphene oxide) quasi-core-shell-shell quantum dots that are applied in the white color LED devices. Our best device achieves a maximum luminance of 484.2 cd/m2 and CIE coordinates (0.35, 0.28).

• Korean Journal of Clinical Pharmacy
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• v.22 no.2
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• pp.153-159
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• 2012

Licorice is a very useful herbal medicine frequently prescribed, but glycyrrhizin, one of its components, can cause pseudoaldosteronism presenting hypokalemia, metabolic alkalosis and hypertension as a result of prolonging a biological half-life of systemic steroid by strongly inhibiting the enzyme $11{\beta}$-hydroxysteroid dehydrogenase type 2. The risk factors for this side effect are still unclear. Here, 479 hospitalized patients taking herbal medicines including licorice for more than five days were recruited to analyze their serum potassium levels, under following parameters ; age and gender of patient, dose and period of licorice, disease state such as hypertension and with or without diuretics. They were divided into the non-occurrence group (over 3.5 mEq/L) and the occurrence group (under 3.5 mEq/L) of hypokalemia based on serum potassium levels during hospitalization. The average ages of the non-occurrence group and the occurrence group were $52.6{\pm}17.8$ and $68{\pm}10.5$, respectively (p < 0.001). But there were no noticeable differences in the daily dose of licorice, days of taking, and total dose between groups. Regression analysis showed that odd ratio of age (>60) and taking diuretics inducing hypokalemia was 3.5 (95%CI 1.5-8.1), 4.6 (95%CI 2.0-10.9) that indicates significant correlation with hypokalemia. Based upon this analysis, it is imperative to monitor regularly the risk of pseudoaldosteronism or hypokalemia not only when administered licorice of high dose for long period but also when combined it with diuretics causing hypokalemia to the elderly patients over 60 year old.

• Korean Journal of Environmental Biology
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• v.28 no.2
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• pp.101-107
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• 2010

Metal ions are essential to life. However, some metals such as mercury are harmful, even when present at trace amounts. Toxicity of mercury arises mainly from its oxidizing properties. Ionizing radiation (IR) is an active tool for destruction of cancer cells and diagnosis of diseases, etc. IR induces DNA double strand breaks in the nucleus, In addition, it causes lipid peroxidation, ceramide generation, and protein oxidation in the membrane, cytoplasm and nucleus. Yeasts have been a commonly used material in biological research. In yeasts, the physiological response to changing environmental conditions is controlled by the cell types. Growth rate, mutation and environmental conditions affect cell size and shape distributions. In this work, the effect of IR and mercury chloride (II) on the morphology of yeast cells were investigated. Saccharomyces cerevisiae cells were treated with IR, mercury chloride (II) and IR combined with mercury chloride (II). Non-treated cells were used as a control group. Morphological changes were observed by a scanning electron microscope (SEM). The half-lethal condition from the previous experimental results was used to the IR combined with mercury. Yeast cells were exposed to 400 and 800 Gy at dose rates of 400Gy $hr^{-1}$ or 800 Gy $hr^{-1}$, respectively. Yeast cells were treated with 0.05 to 0.15 mM mercury chloride (II). Oxidative stress can damage cellular membranes through a lipidic peroxidation. This effect was detected in this work, after treatment of IR and mercury chloride (II). The cell morphology was modified more at high doses of IR and high concentrations of mercury chloride(II). IR and mercury chloride (II) were of the oxidative stress. Cell morphology was modified differently according to the way of oxidative stress treatment. Moreover, morphological changes in the cell membrane were more observable in the frequently stress treated cells than the temporarily stress treated cells.

• Korean Journal of Clinical Pharmacy
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• v.14 no.2
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• pp.78-84
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• 2004

Nifedipine, one of calcium channel antagonists, has been used for the treatment of mild to moderate hypertention, angina pectoris, Raynaud's phenomenon and various other cardiovascular diseases. Because of its short biological half-life, several sustained-release (SR) formulations of nifedipine have been developed. and used clinically. The bioequivalence of the two nifedipine SR preparations was evaluated according to the guidelines of KFDA. The test product was Hanmi Nifedipine SR $tablet^{(R)}$ made by Hanmi Pharm. Co. and the reference was Adalat Oros $tablet^{(R)}$ made by Bayer Korea. Thirty healthy male subjects were divided into two groups and a randomized $2\times2$ cross-over study was employed. After one SR tablet containing 33 mg of nifedipine was orally administered, blood sample was taken at predetermined time intervals and the concentrations of nifedipine in plasma were determined using a validated HPLC method with UV detector. Two pharmacokinetic parameters, $AUC_t\;and\;C_{max}$, were calculated and analyzed statistically for the evaluation of bioequivalence of the two products. Analysis of variance was carried out using logarithmically transformed parameter values. The $90\%$ confidence intewals of the $AUC_t\;and\;the\;C_{max}\;were\;log\;0.81\sim1og\;1.19\;and\;log\;0.84\sim\;log\;1.13,\;respectively.$ These values were within the acceptable bioequivalence intervals from log 0.8 to log 1.25 in KFDA guidelines. Thus, the criteria of the KFDA guidelines for the bioequivalence was satisfied, indicating that Hanmi Nifedipine SR tablet is bioequivalent to Adalat Oros tablet.

• Journal of Pharmaceutical Investigation
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• v.35 no.1
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• pp.51-55
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• 2005

A high-performance liquid chromatographic method was employed for the determination of bumetanide in human plasma. After addition of internal standard (IS, naproxen) and acidification of the plasma with 1 M hydrochloric acid, the drug and IS were extracted into dichloromethane. The organic phase was back-extracted into 1 M sodium bicarbonate solution and 50 ${\mu}l$ of the aqueous phase was injected onto a reversed-phase C18 column with a mobile phase consisting of methanol: water: glacial acetic acid = 65 : 35 : 1. The samples were detected utilizing a fluorescence detector (excitation wavelength 235 nm, emission wavelength 405 nm). The method was specific and validated with a lower limit of 5 ng/mL. Intra- and inter-day precision and accuracy were acceptable for all quality control samples including the lower limit of quantification. The applicability of the method was demonstrated by analysis of plasma after oral administration of a single 2 mg dose to 24 healthy subjects. From the plasma bumetanide concentration vs. time curves, the mean AUC was $246.5{\pm}73.8\;ng{\cdot}hr/mL$ and $C_{max}$ of $132.1{\pm}40.9$ ng/mL reached 1.2 hr after administration. The mean biological half-life of burnet ani de was $1.1{\pm}0.2$hr. Based on the results, this simple and validated assay method could readily be used in any pharmacokinetic or bioequivalence studies using humans.

• Journal of Pharmaceutical Investigation
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• v.35 no.6
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• pp.461-465
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• 2005

A simple HPLC method with ultraviolet detection of nicardipine in human plasma was developed and validated. After drug extraction with solid phase extraction (SPE) method, chromatographic separation of nicardipine in plasma was achieved at $30^{\circ}C$ with a $C_{18}$ column and acetonitrile-0.02% phosphate buffer mixture (with 0.02% triethylamine, final pH 7.0), as mobile phase. Quantitative determination was performed by ultraviolet detection at 254 nm. The method was specific and validated with a limit of quantification of 5 ng/mL. The intra- and inter-day precision and accuracy were acceptable for all quality control samples including the lower limit of quantification. The applicability of the method was demonstrated by analysis of plasma after oral administration of a single 40 mg dose to 8 healthy subjects. From the plasma nicardipine concentration versus time curves, the mean $AUC_{t}$, was $134.04{\pm}59.72\;ng\;hr/mL$ and $C_{max}$ of $108.65{\pm}69.17\;ng/mL$ reached 1.5 hr after administration. The mean biological half-life of nicardipine was $3.93{\pm}0.82\;hr$. Based on the results, this simple and validated assay method could readily be used in any pharmacokinetic or bioequivalence studies using human.

• The Korean Journal of Pesticide Science
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• v.15 no.2
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• pp.97-103
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• 2011

The residual patterns of azoxystrobin and cyenopyrafen were investigated to compare the differences between rainshield and plastic house conditions of the grapes. Initial residue concentrations of azoxystrobin were $0.54\;mg{\cdot}kg^{-1}$ under rainshield condition and $0.9\;mg{\cdot}kg^{-1}$ under plastic house condition. And cyenopyrafen was 0.55 and $0.64\;mg{\cdot}kg^{-1}$ respectively. Biological half-life of azoxystrobin was calculated as 13.28 days under rainshield and 15.58 days under plastic house condition. And cyneopyrafen was 7.99 and 12.65 days, respectively. In comparison with two different cultivation conditions, pesticides in/on the grape were decomposed more faster under plastic house than rain shield conditions.