• 한국산업보건학회지
• /
• 제24권2호
• /
• pp.146-151
• /
• 2014

Objectives: Chrysotile is mineralogically distinct from amphiboles, displaying a notably different chemical structure. The thin sheets that form chrysotile fiber lead to the ability of the lung/macrophage system to decompose the chrysotile fibers. This study was performed in order to compare the physicochemical characteristics of Korean asbestos with those of Canadian amphiboles. Materials: An acid solubility test for each test substance was done to compare pH 4.5 and pH 1.2 distilled water. Asbestos fibers which had been placed in acid solutions for five days, five weeks and weeks were analyzed with a transmission electron microscope equipped with an energy dispersive X-ray spectrometer (TEM-EDS). Results: The composition element (Mg) of Korean chrysotile, Korean anthophyllite and Canadian amosite significantly decreased from 5 days and also decreased significantly after 5 weeks and 10 weeks. Only the composition (Mg) of Canadian crocidolite did not change under any conditions. From 5 days, the Mg of Korean chrysotile, Korean anthophyllite and Canadian amosite were significantly lower than before the acid treatment, but there were no changes over time or by the pH of the acid solutions. Particularly after 10 weeks, the composition (Mg) of Korean chrysotile in the pH 1.2 acid solution showed a rapid reduction of 15.86%. Conclusions: Korean chrysotile was very weak in an acid environment, beginning to show significant changes after 5 days. The Mg component rapidly decreased after 10 weeks in the pH 1.2 acid solution.

• Environmental Analysis Health and Toxicology
• /
• 제25권2호
• /
• pp.131-143
• /
• 2010

We performed the tests of acute and subchronic inhalation toxicity of methyl formate, which has limited toxicological data in spite of its widespread use and enhanced hazard consequent on its high volatility. The median lethal concentration ($LC_{50}$) was evaluated to be above 5,000ppm(12.27 mg/L). In the test with subchronic inhalation, there are no deaths, but with reduction of body weight, food intake, organ weight by exposure to 400 (0.98 mg/L) and 1,600 (3.92 mg/L) ppm, dose-dependently. There were statistical differences in some hematological and blood biochemical parameters as compared to control (e.g. neutrophile and lymphocyte in the 1,600 ppm group, calcium and A/G in 1,600 ppm group). Methyl formate under the exposure of 1,600 ppm showed the respiratory findings with nasal, it was confirmed that the chemical has respiratory hazard with 1,600 ppm inhalation exposure, induces nasal epithelial atrophy, olfactory cell degeneration/regeneration and the contraction of olfactory cells, etc. According to the notification with Ministry of Labor (No. 2009-68) for classification, labeling and MSDS of chemicals, it is suggested for methyl formate to be classified as category 4 in acute (10.0$4\leq20.0$ mg/L), category 2 (0.2$\leq$1.0 mg/L/6h, 90 days) in specific target organ-repeated exposure.

• Environmental Analysis Health and Toxicology
• /
• 제21권2호
• /
• pp.115-126
• /
• 2006

This study was conducted to find out survival rate, activity, growth and change of the organ structure of bivalves exposed to heavy metal. The results of the study confirmed that zinc (Zn) induces reduction of survival rate and activity, abnormality of organ structure of the equilateral venus, Gomphina veneriformis. Experimental groups were composed of one control condition and three Zn exposure conditions ($0.64mg\;Zn{\iota}^{1},\;1.07mg\;Zn{\iota}^{-1},\;1.79mg\;Zn{\iota}^{-1}$). As the concentration of zinc increased the accumulation of lipofucin increased in the digestive gland. Survival rate was the lowest in the lowest Zn exposure group at $0.64mg;Zn{\iota}^{-1}$. Growth was not significantly different between the control and exposure group. Activity. with the exception of the lowest Zn exposure group at $0.64mg\;Zn{\iota}^{-1}$, was similar between the control and exposure group. Histological analysis of organ system illustrated expansion of hemolymph sinus, loss of striated border of inner epidermis, increase in the number of mucous cell in the mantle. Also, histological degenerations as epithelial necrosis and hyperplasia of mucous cells are recognized in the gill and foot.

• 대한수의학회지
• /
• 제43권4호
• /
• pp.657-666
• /
• 2003

The present study was undertaken to evaluate the potential adverse effects of 2-BP on pregnant dams and embryo-fetal development after maternal exposure during the gestational days (GD) 6 through 19 in Sprague-Dawley rats. The test chemical was administered subcutaneously to pregnant rats at dose levels of 0, 375, 750 and 1250 mg/kg/day. During the test period, clinical signs, mortality, body weights and food consumption were examined. All dams were subjected to caesarean section on GD 20 and their fetuses were examined for external, visceral and skeletal abnormalities. At above 750 mg/kg, toxic effects including signs of toxicity, suppressed body weight, decreased gravid uterine weight and reduced food intake were observed in pregnant dams. An increase in the fetal deaths, a decrease in the litter size, a reduction in the fetal body weight and an increase in the incidence of fetal morphological alterations were also found. There were no adverse effects on either pregnant dams or embryo-fetal development at a dose level of 375 mg/kg. These results suggest that a 14-day subcutaneous dose of 2-BP is embryolethal and teratogenic at above 750 mg/kg/day in pregnant rats. In the present experimental condition, the no-observed-adverse-effect level of 2-BP is considered to be 375 mg/kg/day for dams and embryo-fetuses, respectively.

• Journal of Ecology and Environment
• /
• 제31권4호
• /
• pp.341-344
• /
• 2008

We investigated the responses of red squirrels to pine nuts (Pinus koraiensis) treated with Lithium Chloride (LiCl) and the potential of the chemical for inducing conditioned taste aversion (CTA) in red squirrels. In red squirrels, nut feeding declined dramatically during the first 4 days after feeding with LiCl-treated nuts. The ratio of LiCl-treated nuts eaten to total nuts eaten declined from the $1^{st}$ day in LC-1 and the $2^{nd}$ day in LC-2, along with a general reduction in quantity eaten. Thus, feeding with LiCl-treated nuts induced CTA from the 2nd day after feeding, and CTA remained constant until the $4^{th}$ day, but disappeared on the $5^{th}$ day. The squirrels ate an average of $757.0{\pm}106.1mg$ (n = 2, range $682.0\sim832.0$) of LiCl before dying on the $16^{th}$ day of the study. The lethal dose of LiCl was 2.32 mg LiCl/g body weight, and the average amount of LiCl needed to induce CTA was $23.0{\pm}4.24mg$ (20 mg in LC-1 and 26 mg in LC-2).

• 에너지공학
• /
• 제25권4호
• /
• pp.1-6
• /
• 2016

일반적으로 해수담수화플랜트는 크게 두 가지의 문제점을 가지고 있는데, 에너지 비효율성과 해수담수화 후 부산물인 농축수의 해결방안이다. 전자는 태양에너지 등 신 재생에너지원의 활용과 새로운 기술에 대한 꾸준한 연구개발로 상당히 그 효율성이 개선되었으나, 농축수 해결방안에 대한 연구는 아직 미미한 실정이다. 본 논문에서는 많은 에너지를 투입하여 담수와 함께 생산된 농축수의 활용과 관련하여 제염이 가능한 설비의 구축과 그 효용성을 제고하기 위한 미네랄(Mg) 성분 제어에 관하여 제주 MVR해수담수화 플랜트를 중심으로 그 연구 결과를 소개하고자 한다. 플랜트의 정상 작동으로 생산된 농축수에 본 연구의 제염 설비를 적용하여 단계별 소금의 성분 함량을 분석했을 때 Mg 성분 수치가 줄어드는 것으로 보아 미네랄(Mg) 제어가 정상적으로 진행되고 있음을 알 수 있었다. 아울러, 본 MVR해수담수화 플랜트의 에너지 이용의 효율성과 담수 생산 및 농축수 활용에 관하여 그 활용성을 확인할 수 있었다.

• 소성∙가공
• /
• 제18권4호
• /
• pp.296-303
• /
• 2009

The effect of porosity on the high-cycle fatigue properties of Al-Si-Mg casting aluminum alloys was investigated in this study. Microstructure examination, tensile and high-cycle fatigue test were conducted on both Al-Si-Mg casted (F) and heat-treated (T6) conditions. Porosity characteristics on the fracture surfaces of fatigue-tested samples were examined using SEM and image analysis. The microstructure observation results showed that eutectic Si particles were homogeneously dispersed in the matrix of the Al-Si-Mg casting alloys, but there were porosities formed as cast defects. The high-cycle fatigue results indicated that the fatigue strength of the 356-T6 alloy was higher than that of the 356-F alloys because of the significant reduction in volume fraction of pores by heat treatment. The SEM fractography results showed that porosity affected detrimental effect on the fatigue life: 80% of all tested samples fractured as a result of porosity which acted as the main crack initiation site. It was found that fatigue life decreased as the size of the surface pore increased. A comparison was made between surface pore and inner pore for its effect on the fatigue behavior. The results showed that the fatigue strength with the inner pores was higher than that of the surface pore.

• Journal of Plant Biotechnology
• /
• 제44권3호
• /
• pp.335-342
• /
• 2017

Purple passion fruit (Passiflora edulis Sims) is one of the introduced tropical plants, an increasing interest has arisen due to its distinctive taste and attractive flavor. It is expected that passion fruit production and planted area will increase gradually in the years ahead because of high profitability and consumer's demands of healthful ingredients. So we tried to investigate the effect of plant growth regulators and antioxidants on in vitro plant regeneration and callus induction from leaf explants of passion fruit for an establishment of optimal mass propagation system. Young leaf explants of purple passion fruit were cultured in Murashige and Skoog (MS) medium containing different growth regulators and antioxidant additives to induce the shoot organogenesis. After 8 weeks, the highest embryogenic callus formation rate was obtained in MS medium supplemented with $1mg{\cdot}L^{-1}$ 6-benzylaminopurine (BAP) and $2mg{\cdot}L^{-1}$ 2,4-dichlorophenoxyacetic acid (2,4-D), furthermore, the shoot development via organogenesis was also observed. Silver nitrate ($AgNO_3$), which was added into the medium to minimize the adverse effects of leached phenolics, was effective for reduction of medium browning and sudden explant death. In the medium supplemented with $1mg{\cdot}L^{-1}$ BAP and $1mg{\cdot}L^{-1}$ gibberellic acid ($GA_3$), shoots were most vigorously regenerated and elongated. Most shoots rooted successfully in half strength medium with $1mg{\cdot}L^{-1}$ indol-3 acetic acid (IAA), and more than 90% of plantlets survived after 4-month acclimatization period.

• 한국식품조리과학회지
• /
• 제32권6호
• /
• pp.818-827
• /
• 2016

Purpose: This study was conducted to investigate the effect of freeze-dried Gastrodiae rhizoma powder (GR) on the liver function and alcohol metabolism in alcohol treated rats. Methods: The rats were administered various concentrations of GR (100 mg, 200 mg, 300 mg/kg B.W.) for 3 days 1 hour before 50% (v/v) ethanol (3 g/kg B.W.) administration. Two tests focusing on liver function and alcohol metabolism in acute alcohol treatment were carried out. Results: Glutamic oxaloacetic transaminase activity was significantly increased by alcohol treatment, and was decreased by 100 mg GR administration. Acute ethanol treatment led to significant increase in alcohol and acetaldehyde levels of serum and liver. However, 100 mg GR administration led to a significant reduction in increased alcohol level in the serum with decreased alcohol dehydrogenase (ADH) activity and increased acetaldehyde level in liver was significantly reduced by three levels. Conclusion: These results suggest that GR can be effective in enhancing liver function and alcohol metabolism in the alcohol-treated rats. Studies on the appropriate dosage of GR should further be developed to treat alcohol detoxification and stimulate liver function.

• 한국재료학회지
• /
• 제4권3호
• /
• pp.349-356
• /
• 1994

재료의고온소성변형과 수명예측 및 수명향상을 위하여 재료의 변형기구를 규명하는 것이 매우 중요하다. 이를 위하여 전위환모델이 자주 사용되며, 현재 실험적인 결과를 토대로 한 두개의 중요한 전위환모델로서, Orlova등고 Mills등이 제시한 모델들이 있다. 이들은 모두AI-5.5at.%MG을 사용하였으나 상호 상반된 전위환모델을 설명하고 있다. 그러므로 본 연구에서는 상반된 전위환 모델을 확인하기 위하여 AI-5.5at.%MG을 사용하여 573K의 약 30MPa에서 $\varepsilon$=0.03까지 크\ulcorner시험을 하고, 이러한 크\ulcorner시험후 이어서 각각 약 15,10 및 oMPa의 응력감소 시험도 수행하였으며, 동시에 응력감소 시험 전과 후의 전위구조를 관찰하여 전위환모델을 고찰하였다.