• BMB Reports
• /
• v.40 no.1
• /
• pp.82-87
• /
• 2007

Our heterologous expression system of the human ferritin H-chain gene (hfH) allowed us to characterize the cellular effects of ferritin in yeasts. The recombinant Saccharomyces cerevisiae (YGH2) evidenced impaired growth as compared to the control, which was correlated with ferritin expression and with the formation of core minerals. Growth was recovered via the administration of iron supplements. The modification of cellular iron metabolism, which involved the increased expression of high-affinity iron transport genes (FET3 and FTR1), was detected via Northern blot analysis. The findings may provide some evidence of cytosolic iron deficiency, as the genes were expressed transcriptionally under iron-deficient conditions. According to our results examining reactive oxygen species (ROS) generation via the fluorescence method, the ROS levels in YGH2 were decreased compared to the control. It suggests that the expression of active H-ferritins reduced the content of free iron in yeast. Therefore, present results may provide new insights into the regulatory network and pathways inherent to iron depletion conditions.

• Bulletin of the Korean Chemical Society
• /
• v.9 no.5
• /
• pp.289-291
• /
• 1988

The ratio of trivalent to divalent copper has been determined by the redox titration for two superconducting phases of $YBa_2Cu^{3+}_{2x}Cu^{2+}_{3-2x}O_{6.5+x}$ with the onset temp. of 60K (x = 0.23 ${\pm}$ 0.01) and 90K (x = 0.35 ${\pm}$ 0.02), and for the insulating one (x ${\cong}$ 0) which was kept in an ambient atmosphere for 72 hrs. It is found that $T_c$, and the ratio of $Cu^{3+}/Cu^{2+}$ depend strongly on the annealing temperature and time. A typical orthorhombic phase can easily be obtained by a slow cooling or stepwise cooling at $PO_2$ = 1 atm, and shows a high Tc (ca. 90K) superconductivity.

• Smart Structures and Systems
• /
• v.30 no.5
• /
• pp.433-446
• /
• 2022

Despite efforts to reduce unexpected accidents at confined construction sites, choking accidents continue to occur. Because of the poorly ventilated atmosphere, particularly in long, confined underground spaces, workers are subject to dangerous working conditions despite the use of artificial ventilation. Moreover, the traditional monitoring methods of using portable gas detectors place safety inspectors in direct contact with hazardous conditions. In this study, a long-range (LoRa)-based wireless safety monitoring system that features the network organization, fault-tolerant, power management, and a graphical user interface (GUI) was developed for underground construction sites. The LoRa wireless data communication system was adopted to detect hazardous gases and oxygen deficiency within a confined underground space with adjustable communication range and low power consumption. Fault tolerance based on the mapping information of the entire wireless sensor network was particularly implemented to ensure the reliable operation of the monitoring system. Moreover, a sleep mode was implemented for the efficient power management. The GUI was also developed to control the entire safety-monitoring system and to manage the measured data. The developed safety-monitoring system was validated in an indoor testing and at two full-scale water pipeline construction sites.

• Ocean and Polar Research
• /
• v.27 no.3
• /
• pp.299-309
• /
• 2005

The community structure of meiobenthos was studied in the sediment of Kongfjorden, Spitsbergen of Svalbard Island in the Arctic Sea. Samples of meiobenthos were collected in August, 2003. Meiobenthic organisms were collected by SCUBA and van veen grab or acryl sub-corers 34mm in internal diameter, and were taken from upper sediment to a depth of 3cm at each station. A total of 26 meiofaunal groups were found in the sediment of Spitsbergen in Svalbard Island. Nematodes were the most dominant faunal group. Sarcomastigophorans, benthic harpacticoids, and nauplius larvae of crustaceans, were also important components of the meiobenthic community of Kongsfjorden. All of these low faunal groups were comprised of more than 90% of total meiobenthos at every station. The total density of meiobenthos at each station was highest at station MeG 6 $(3,583{\pm}1,137inds./10cm^2)$, and lowest at station $MeG9(28{\pm}1inds./10cm^2)$. Meiobenthos in general showed the highest density in the upper 1cm layer. This may be associated with food and oxygen supply to subsurface. Harpacticoids showed extreme preference at the surface and little presence in layers deeper than 2cm. These animals may be less resistant to oxygen deficiency, and nauplius also showed the same trend. However, in St. MeG 8 and 9, meiobenthos were dense at depths of more than 0-1cm, at especially at depths of 2-3m because of relatively easy penetration of oxygen. Based on the results of cluster analysis, three meiobenthos assemblages were distinguished: one was in the outer and two were in the inner fjord. Station SCU 5 was grouped with the meiobenthos assemblage located in the outer fjord. The outer ford community was characterised by : 1) a relatively low mean number of meiobenthos taxa, 2) a relatively high density of harpacticods and nauplius. One of the inner ford communities (a group of four nation: MeG 2, 3, 8, 9) was in the proximity of the glaciers. Specifically, it was characterised by : 1) a low mean number of meiobenthos taxa, 2) a low density. The other inner ford community was characterised by both a high density and great mean number of meiofaunal taxa.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.1
• /
• pp.31-37
• /
• 2016

Co-firing of biomass with coal is a promising combustion technology in a coal-fired power plant. However, it still requires verifications to apply co-firing in an actual boiler. In this study, data from the Thermogravimetric analyzer(TGA) and Drop tube furnace(DTF) were used to obtain the combustion characteristics of biomass when co-firing with coal. The combustion characteristics were verified using experimental results including reactivity from the TGA and Unburned carbon(UBC) data from the DTF. The experiment also analyzed with the variation of the biomass blending ratio and biomass particle size. It was determined that increasing the biomass blending ratio resulted in incomplete chemical reactions due to insufficient oxygen levels because of the rapid initial combustion characteristics of the biomass. Thus, the optimum blending condition of the biomass based on the results of this study was found to be 5 while oxygen enrichment reduced the increase of UBC that occurred during combustion of blended biomass and coal.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.19 no.4
• /
• pp.381-389
• /
• 2009

Confined spaces are inherently dangerous workplace and many fatal and nonfatal accidents have been reported. Even though these accidents occur in various kinds of confined spaces, there has rarely been reported on the health hazard agent, i.e., the types of gases and their concentration ranges. Therefore in this study, we evaluated several toxic and asphyxiating gas concentrations in various confined spaces. We surveyed 57 manholes, 3 sewage treatment plants, 2 yellow radish manufacturing companies and 7 barges to measure the concentrations of oxygen($O_2$), hydrogen sulfide($H_2S$), carbon monoxide(CO), ammonia($NH_3$). Lower Explosion Limits(LEL) and Volatile Organic Compounds (VOCs). Those four types of confined spaces occupies 56% of accidents during last 9 years in Korea. In 57 manholes, the concentration varied according to the types of manholes; rainfall and sewage, and by location; residential and industrial areas. Sewage manhole in industrial area was evaluated as the most hazardous than other types of manhole like rainfall manholes, residential sewage manholes. The highest $H_2S$ concentration and the lowest $O_2$ concentration at sewage manhole in industrial area were 300 ppm, 8.7% respectively. In 3 sewage treatment plants, $H_2S$ and $NH_3$ concentrations were reached up to the 500 ppm and 200 ppm respectively. Two yellow radish manufacturing companies showed the concentrations of 316 ppm, 505.2 ppm, 90 ppm and 15.7% for $H_2S$, CO, VOCs and $O_2$, respectively. Seven barges showed 15.9%~20.9% oxygen concentration. Gas species and concentration ranges varied by the types and location of confined spaces; CO, $H_2S$, $O_2$ could be hazardous in manhole, especially manhole connected to sewage plants. CO, $H_2S$, LEL, $O_2$, $NH_3$ should be controlled in sludge silo and sluge pumping confined spaces in sewage treatment plant. The activity of lifting out radish from the storage tank was evaluated more hazardous rather than the other activities in yellow radish manufacturing industry. The employers must conduct the survey to identify all possible confined spaces in their local workplace prior to performing the tasks. At the national level to reduce the accidents in the confined spaces, we suggest that systemic approach and active education program including possible hazards, standard operation procedures, ventilation plan, and personal protective equipment in confined spaces should be implemented.

• Journal of Embryo Transfer
• /
• v.32 no.4
• /
• pp.257-265
• /
• 2017

Ferulic Acid (FA) is a metabolite of phenylalanine and tyrosine, a phenolic compound commonly found in fruits and vegetables. Several studies have shown that FA has various functions such as antioxidant effect, prevention of cell damage from irradiation, protection from cell damage caused by oxygen deficiency, anti-inflammatory action, anti-aging action, liver protective effect and anti-cancer action. In this study, we investigated the maturation rate, intracellular glutathione (GSH) and reactive oxygen species (ROS) of porcine oocytes by adding FA to the in vitro maturation (IVM) medium and examined subsequent embryonic developmental competence at 5% oxygen through parthenogenesis. There is no significant difference between the control group ($0{\mu}M$) and treatment groups ($5{\mu}M$, $10{\mu}M$, $20{\mu}M$) on maturation rates. Intracellular GSH levels in oocyte treated with $5{\mu}M$ of FA significantly increased (P < 0.05), and $20{\mu}M$ of FA revealed significant decrease (P < 0.05) in intracellular ROS levels compared with the control group. Oocytes treated with FA exhibited significantly higher cleavage rates (79.01% vs 89.19%, 92.20%, 90.89%, respectively) than the control group. Oocytes treated with $10{\mu}M$ showed significantly higher blastocyst formation rates (28.3% vs 40.3%, respectively) after PA than the control group. Total cell numbers in blastocyst of $10{\mu}M$ FA displayed significantly higher (39.4 vs 51.9, respectively) than the control group. In conclusion, these results suggested that treatment with FA during IVM improved the developmental potential of porcine embryos by increasing intracellular GSH synthesis and reducing ROS levels. Also, there was an improvement of cleavage rate, blastocyst formation and total cell numbers in blastocysts. It might be associated with Keap1-Nrf2 pathway as an antioxidant regulate pathway that plays a crucial role in determining the sensitivity of cells to oxidative damages by regulating the basal and inducible expression of enzymes which is related to detoxification and anti-oxidative effects, stress response enzymes and/or proteins and ABC transporters.

• Journal of Life Science
• /
• v.14 no.2
• /
• pp.280-285
• /
• 2004

The ovarian hormone-deficiency induced ovariectomy rat is widely used as an aging model due to its practicality, convenience, and cost effectiveness. The surgically ovariectomized rat induces reactive oxygen species (ROS) generation like aging phenomena. Free oxygen radicals have been proposed as important causative agents of aging. The purpose of this study was to investigate the effect of chondroitin sulfate (CS) to prevent ovariectomy (OVX)-induced oxidative stress. The OVX rats were given intraperitoneally CS at doses of 100 mg/kg and 200 mg/kg daily for fifteen weeks. Malondialdehyde (MDA) levels were determined as well as the activities of superoxide dismutase (SOD), catalase (CAT), reduced-glutathione (GSH), oxidized-glutathione (GSSG), glutathione peroxidase (GPx) in the liver. The liver antioxidative enzyme activity was elevated while MDA concentration decreased in all CS treated animals. The results demonstrated that CS reduced oxidative stress in a dose dependent manner. These results suggest that CS might be a useful candidate for antioxidative reagent.

• Journal of the Korean Ceramic Society
• /
• v.38 no.10
• /
• pp.886-893
• /
• 2001

We synthesized $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_{3-\delta}$ powders by coprecipitation, citration and solid-state reactions. The oxygen permeation membranes were fabricated by cold isostatic pressing of the synthesized powders, followed by sintering in air. All powders and membranes consist of perovskite phases. The coprecipitated powders showed the highest surface area ($7.5m^2/g$) but strontium deficiency was found during washing and filtering in the process. The membrane with lower relative density was fabricated by citration method. On the other hand, solid state reacted powders had high relative density (95%), and mechanical properties showed superior properties. Especially, the composition of the solid-state reacted powders was relatively well-controlled.

• Animal Bioscience
• /
• v.36 no.7
• /
• pp.1022-1033
• /
• 2023

Objective: p66Shc, a 66 kDa protein isoform encoded by the proto-oncogene SHC, is an essential intracellular redox homeostasis regulatory enzyme that is involved in the regulation of cellular oxidative stress, apoptosis induction and the occurrence of multiple age-related diseases. This study investigated the expression profile and functional characteristics of p66Shc during preimplantation embryo development in sheep. Methods: The expression pattern of p66Shc during preimplantation embryo development in sheep at the mRNA and protein levels were studied by quantitative real-time polymerase chain reaction (RT-qPCR) and immunofluorescence staining. The effect of p66Shc knockdown on the developmental potential were evaluated by cleavage rate, morula rate and blastocyst rate. The effect of p66Shc deficiency on reactive oxygen species (ROS) production, DNA oxidative damage and the expression of antioxidant enzymes (e.g., catalase and manganese superoxide dismutase [MnSOD]) were also investigated by immunofluorescence staining. Results: Our results showed that p66Shc mRNA and protein were expressed in all stages of sheep early embryos and that p66Shc mRNA was significantly downregulated in the 4-to 8-cell stage (p<0.05) and significantly upregulated in the morula and blastocyst stages after embryonic genome activation (EGA) (p<0.05). Immunofluorescence staining showed that the p66Shc protein was mainly located in the peripheral region of the blastomere cytoplasm at different stages of preimplantation embryonic development. Notably, serine (Ser36)-phosphorylated p66Shc localized only in the cytoplasm during the 2- to 8-cell stage prior to EGA, while phosphorylated (Ser36) p66Shc localized not only in the cytoplasm but also predominantly in the nucleus after EGA. RNAi-mediated silencing of p66Shc via microinjection of p66Shc siRNA into sheep zygotes resulted in significant decreases in p66Shc mRNA and protein levels (p<0.05). Knockdown of p66Shc resulted in significant declines in the levels of intracellular ROS (p<0.05) and the DNA damage marker 8-hydroxy2'-deoxyguanosine (p<0.05), markedly increased MnSOD levels (p<0.05) and resulted in a tendency to develop to the morula stage. Conclusion: These results indicate that p66Shc is involved in the metabolic regulation of ROS production and DNA oxidative damage during sheep early embryonic development.