• Advances in environmental research
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• v.11 no.1
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• pp.31-38
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• 2022

The current observational epidemiological study analyzed blood lead levels (BLLs) in occupationally exposed workers from Riyadh region, Saudi Arabia and correlated them with the alterations in the differential cell populations of the WBC panel (lymphocytes [Lym %], mixed [Mid %] cells, and neutrophils [Neu %]). In addition, we examined the effect of confounding factors and their relation to BLLs. BLLs were estimated using the LeadCare II analyzer and hematological parameters using the ADVIA 120 analyser. An inferential analysis was conducted to detect association between the observations and the subjects' clinical characateristics. A total of 132 male subjects were included in the final analyses. Based on CDC guidelines, the subjects were categorized as Group I (BLL <10 ㎍/dL; n=118) or Group II (BLL >10 ㎍/dL; n=14) with average BLLs of 4.4 ㎍/dL and 18.1 ㎍/dL, respectively (p <0.0001). The percentages of Mid cells (p <0.0001) and neutrophils (p=0.048), were significantly altered in subjects with High BLL. A regression analysis indicated that subjects > 50 years of age had significantly higher BLLs (53.2 ㎍/dL) than younger age sub-groups (p <0.0001). Age, education, and profession were significant predictors for lead toxicity. Pb exposure is a major public health issue in Saudi Arabia and calls for further investigations on the cellular and molecular effects on hematological system.

• Composites Research
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• v.20 no.5
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• pp.49-55
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• 2007

Nanocomposite blade for dicing semiconductor wafer is investigated for micro/nano-device and micro/nano-fabrication. While metal blade has been used for dicing of silicon wafer, polymer composite blades are used for machining of quartz wafer in semiconductor and cellular phone industry in these days. Organic-inorganic material selection is important to provide the blade with machinability, electrical conductivity, strength, ductility and wear resistance. Maintaining constant thickness with micro-dimension during shaping is one of the important technologies fer machining micro/nano fabrication. In this study the fabrication of blade by wet processing of mixing conducting nano ceramic powder, abrasive powder phenol resin and polyimide has been investigated using an experimental approach in which the thickness differential as the primary design criterion. The effect of drying conduction and post pressure are investigated. As a result wet processing techniques reveal that reliable results are achievable with improved dimension tolerance.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.5
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• pp.191-195
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• 2023

Three-layer nano-coated films in applications for the back cover of mobile cellular phones were prepared utilizing a roll-to-roll continuous process. By introducing a coating layer with a ceramic/metal/ceramic three-layer structure, the inherent reflective properties of the metals were maintained while electrically insulating properties were maintained. The thickness of the composite coating layer on a large area PET film with a length of 1,500 nm and width of 500 nm was less than 60 nm, and a uniform thickness was maintained in all areas. The transmittance according to the wavelength range (240~1600 nm) of the nanocoating film gradually increases as the wavelength increases, and is about 48 % at 1,000 nm, which is within the infrared region, and about 35.5 % at 550 nm, which is within the visible region. These results meet the required level of coated backcover (< 40 %).

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.2
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• pp.243-254
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• 2002

For the purpose of evaluating the biocompatability of 3 kinds of metallic materials frequently used in pediatric dentistry (stainless steel crown, orthodontic band, orthodontic wire), cellular and molecular studies, including cell growth and proliferation, screening of cell death with determination of types whether necrosis or apoptosis and changes in expressions of related signaling molecules were examined, using cultured human gingival fibroblasts (HGF-1), HGF-1 was cultured in Dulbecco's modified Eagle's medium. among which the 3rd to 6th generations of HGF-1 were used. The specimen were divided into stainless steel crown (R), band (B) and wire (W). The immunocytochemical study was done for the detection of anti-PCNA (proliferating cell nuclear antigen) labeling. With extracted protein, western blot was done for the detection of ERK1/2, JNK, and p38, using individual antibodies. Cultured cells proliferated, remarkably till 7 day and slightly at 11 day. There was no statistical significance in the counts of proliferating HGF-1 between control and experimental groups (p>0.05). Relative growth rates were no statistically significant difference between control and experimental groups (p>0.05). PCNA labeling indexes showing similar patterns in control and experimental groups. The expressions of ERK1 and ERK2, p38 were similar in control and experimental groups. The expression of JNK increased at 1st day, slightly decreased at 4th day and markedly increased at 7th and 11 day. Although the patterns of control and experimental groups were similar, the increased expressions of JNK at late period suggest a possible stress due to inhibited cell growth and proliferation, and worse culture condition. Conclusively, the 3 kinds of metal specimens used in this study did not induce cellular and molecular hazards during short term culture of HGF-1. But, for the better clinical stability, the establishment of long period culture and animal experiment was thought necessary.

• Applied Microscopy
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• v.32 no.4
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• pp.411-419
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• 2002

Metallothionein (MT) is a family of ubiquitous, low molecular weight ($6,000{\sim}7,000D$), cysteine-rich ($30{\sim}35%$) inducible protein with a high affinity to metal ions and has no aromatic amino acids and histidine. Some of the known functions of MT include detoxification of heavy metals and alkylating agents and neutralization of free radicals. Also, this protein has been reported to involve in tumor pathophysiology and therapy resistance. MT expression may affect a number of cellular processes including gene expression, apoptosis, proliferation and differentiation. Many reports on the physiological and biochemical properties of MT have been published, but ultrastructural reports on the localization of MT in human gastric cancer tissues are extremely rare. The present study was undertaken to examine the ultrastructural features and the localization of MT within the gastric adenocarcinoma. Ultrastructures of gastric cancer cells were characterized by the high nuclear cytoplasmic ratio, the interdigitation between cells, the irregular nucleus containing much heterochromatin and the wide distribution of free ribosomes in the cytoplasm. Immunohistochemical reaction for MT was prominent in the gastric adenocarcinoma. And the immunogold labellings were more prominent within the nucleus than the cytoplasm. Particularly, immunogold particles were numerously seen at nulcleolus or nucleolar associated heterochromatin. These results suggest that MT expression by gastric cancer cells is associated with cell proliferative activity and is possibly synthesized in the cytoplasm, and then the protein is transported into the nucleus to participate in any transcriptional steps.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.72-72
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• 2012

Lithium rechargeable batteries have been widely used as key power sources for portable devices for the last couple of decades. Their high energy density and power have allowed the proliferation of ever more complex portable devices such as cellular phones, laptops and PDA's. For larger scale applications, such as batteries in plug-in hybrid electric vehicles (PHEV) or power tools, higher standards of the battery, especially in term of the rate (power) capability and energy density, are required. In PHEV, the materials in the rechargeable battery must be able to charge and discharge (power capability) with sufficient speed to take advantage of regenerative braking and give the desirable power to accelerate the car. The driving mileage of the electric car is simply a function of the energy density of the batteries. Since the successful launch of recent Ni-MH (Nickel Metal Hydride)-based HEVs (Hybrid Electric Vehicles) in the market, there has been intense demand for the high power-capable Li battery with higher energy density and reduced cost to make HEV vehicles more efficient and reduce emissions. However, current Li rechargeable battery technology has to improve significantly to meet the requirements for HEV applications not to mention PHEV. In an effort to design and develop an advanced electrode material with high power and energy for Li rechargeable batteries, we approached to this in two different length scales - Atomic and Nano engineering of materials. In the atomic design of electrode materials, we have combined theoretical investigation using ab initio calculations with experimental realization. Based on fundamental understanding on Li diffusion, polaronic conduction, operating potential, electronic structure and atomic bonding nature of electrode materials by theoretical calculations, we could identify and define the problems of existing electrode materials, suggest possible strategy and experimentally improve the electrochemical property. This approach often leads to a design of completely new compounds with new crystal structures. In this seminar, I will talk about two examples of electrode material study under this approach; $LiNi_{0.5}Mn_{0.5}O_2$ based layered materials and olivine based multi-component systems. In the other scale of approach; nano engineering; the morphology of electrode materials are controlled in nano scales to explore new electrochemical properties arising from the limited length scales and nano scale electrode architecture. Power, energy and cycle stability are demonstrated to be sensitively affected by electrode architecture in nano scales. This part of story will be only given summarized in the talk.

• Journal of Ginseng Research
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• v.42 no.3
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• pp.327-333
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• 2018

Background: Bioactive compounds in plant extracts are able to reduce metal ions to nanoparticles through the process of green synthesis. Panax ginseng is an oriental medicinal herb and an adaptogen which has been historically used to cure various diseases. In addition, the P. ginseng leaves-mediated gold nanoparticles are the value-added novel materials. Its potential as a cosmetic ingredient is still unexplored. The aim of this study was to evaluate the antioxidant, moisture retention and whitening properties of gold nanoparticles (PgAuNPs) in cosmetic applications. Methods: Cell-free experiments were performed to evaluate PgAuNP's antioxidant and moisture retention properties and inhibition activity on mushroom tyrosinase. Furthermore, in vitro cell cytotoxicity was evaluated using normal human dermal fibroblast and murine B16BL6 melanoma cells (B16) after treatment with increasing concentrations of PgAuNPs for 24 h, 48 h, and 72 h. Finally, in vitro cell assays on B16 cells were performed to evaluate the whitening effect of PgAuNPs through reduction of cellular melanin content and tyrosinase activity. Results: In vitro DPPH radical scavenging assay results revealed that PgAuNPs exhibited antioxidant activity in a dose-dependent manner. PgAuNPs exhibited moisture retention capacity and effectively inhibited mushroom tyrosinase. In addition, 3-(4,5-dimethyl-thiazol-2yl)-2,5-diphenyl tetrazolium bromide results revealed that PgAuNPs were not toxic to human dermal fibroblast and B16 cells; in addition, they significantly reduced melanin content, tyrosinase activity, and mRNA expression of melanogenesis-associated transcription factor and tyrosinase in B16 cells. Conclusion: Our study is the first report to provide evidence supporting that P. ginseng leaves-capped gold nanoparticles could be used as multifunctional ingredients in cosmetics.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.31 no.2 s.51
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• pp.197-206
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• 2005

In the present study, the Chuncheon buckwheat extracts prepared from its seed coats, seeds and stems were used to determine anti-oxidative effects, the content of rutin and phytic acid, and the protective role against cadmium at the cellular level. futhermore, it was evaluated whether the buckwheat, mainly known as a healthy food source, might be applicable to functional cosmetics. Up to $100 {\mu}g/mL$ of the extract was not toxic in HaCaT and B16F10 cell lines using MTT assay. The anti-oxidative capacity of superoxide radicals was shown in seed coats extracts > stem extracts=seed extracts. Although its content of rutin, known as one of effective anti-oxidants, mainly exists in the stem, any extract did not eliminate hydroxyl radicals. Phytic acid, known as a heavy metal-chelate agent, was highly concentrated in the stem. The Chuncheon buckwheat extract had $10\%$ protective effect against the treatment of $50{\mu}M$ cadmium at which $50\%$ of HaCaT cells survived. Confocal laser scanning microscope revealed the intracellular generation of reactive oxygen species (ROS) by cadmium treatment. Finally, we identified that the stem extract had the most protective effect on the elimination of ROS.

• Journal of Marine Life Science
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• v.3 no.2
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• pp.74-80
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• 2018

Mercury (Hg) poses a threat to marine ecosystem due to continuous inflow from various industries and bioaccumulation to higher trophic level via food web. Mercury can adversely affect growth, development, reproduction and metabolism to aquatic organisms. In the present study, acute toxicity and oxidative stress markers (total glutathione content, and activities of GST, GR and GPx) were investigated in brackish water flea Disphanosoma celebensis exposed to HgCl₂ for 24 h. As results, Hg showed negative effect in survival of D. celebensis. 24 h-LC₅₀ value was determined as 0.589 mg/l (95% C.I. 0.521~0.655 mg/l). After exposure to Hg (0.08 and 0.4 mg/l) for 24 h, total glutathione content was significantly decreased, whereas GST, GPx and GR activities were enhanced. These findings indicate that Hg induced oxidative stress in D. celebensis, and oxidative stress markers may be involved in cellular defense against Hg - mediated toxicity. This study provides a better understanding of molecular mode of action of Hg toxicity in this specie and potent of molecular markers for heavy metal monitoring in marine ecosystem.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.4
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• pp.288-295
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• 2010

Metal exposure experiments using polychaete (Perinereis nuntia) as a bio-indicator of trace metals contamination were conducted to evaluate the bioaccumulation and the biomarkers responses such as metallothionein-like protein (MTLPs) and glutathione S-transferase (GST) which was simultaneously exposed to Cadmium (Cd) and Copper (Cu). Cu and Cd concentrations in polychaete were enhanced with increasing exposure time and their concentrations of aqueous medium. Initial accumulation of Cd was higher than that of Cu. Our results showed that the bioaccumulation of Cu and Cd were prohibited, especially at higher Cu levels, suggesting the different cellular uptake mechanisms when Cu and Cd are co-exist. Net accumulation rate of Cu was declined with exposure time but it did not show any significant change for Cd. Although the highest MTLPs concentration was observed at 6 hr of exposure time, it did not show any significant change related to exposure times and metals concentrations. An increase of GST activity tended to increase as a function of exposure time and metals concentrations. And GST activities in P. nuntia have similar tendency with bioconcentration factors in high concentration of Cu (treatment group IV) at post 24 h of exposure. Our results provide new information of the bioaccumulation and biomarker responses to understand the effects of co-existing contaminants (Cu and Cd) using polychaete. Further studies are required to elucidate the bioaccumulation and biomarkers responses for various contaminants.