• Transactions on Electrical and Electronic Materials
• /
• v.10 no.6
• /
• pp.217-221
• /
• 2009

The use of the carbon nanotube (CNT) is superior to the general powder state materials in their thermal and chemical properties. Because its ratio of diameter to length (aspect ratio) is very large, it is known to be a type of ideal nano-reinforcement material. Based on this advantage, the existing carbon black of the semiconductive shield materials used in power cables can acquire excellent properties by the use of a small amount of CNTs. Therefore, we fabricated specimens using a solution mixing method. We investigated the thermal properties of the CNT, such as its storage modulus, loss modulus, and its tan delta using a dynamic mechanical analysis 2980. We found that a high thermal resistance level is demonstrated by using a small amount of CNTs. We also investigated the chemical properties of the CNT, such as the oxidation reaction by using Fourier transform infrared spectroscopy (FT-IR) made by Travel IR. In the case of the FT-IR tests, we searched for some degree of oxidation by detecting the carboxyl group (C=O). The results confirm a tendency for a high cross-linking density in a new network in which the CNTs situated between the carbon black constituent molecules show a bond using similar constructive properties.

• Preventive Nutrition and Food Science
• /
• v.22 no.2
• /
• pp.107-117
• /
• 2017

The purpose of this study was to evaluate the antioxidant and anticholinesterase activities of yellow and white bitter yams from South Western Nigeria using methanolic extraction and simulated gastrointestinal digestion models. The phenolic compounds in the bitter yam varieties were evaluated by high performance liquid chromatography with a diode array detector (HPLC-DAD). The total phenolic content of the bitter yams was measured by the Folin-Ciocalteu method, reductive potential by assessing the ability of the bitter yam to reduce $FeCl_3$ solution, and the antioxidant activities were determined by the 2,2-diphenyl-1-picrylhydrazyl radical ($DPPH^{\cdot}$) scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation ($ABTS^{{\cdot}+}$) scavenging activity, nitric oxide radical ($NO^{\cdot}$) scavenging ability, hydroxyl radical scavenging ability, and ability to inhibit $Fe^{2+}$-induced lipid oxidation. The HPLC-DAD analysis revealed the presence of some phenolic compounds in the studied bitter yam varieties, with varying degree of quantitative changes after cooking. The antioxidant indices (total phenolic content, total flavonoid content, reducing power, $DPPH^{\cdot}$ scavenging activity, $ABTS^{{\cdot}+}$ scavenging activity, and $NO^{\cdot}$ scavenging activity) were higher in the simulated gastrointestinal digestion model compared to the methanolic extract, with the in vitro digested cooked white bitter yam ranking higher. Similarly, the in vitro digested yams had a higher inhibitory action against lipid oxidation compared to the methanolic extracts, with the cooked white bitter yam ranking high. The methanolic extracts and in vitro enzyme digests showed no acetylcholinesterase inhibitory abilities, while methanolic extracts and the in vitro enzyme digest displayed some level of butyrylcholinesterase inhibitory activities. Therefore the studied bitter yams could be considered as possible health supplements.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2016.11a
• /
• pp.198-198
• /
• 2016

An ideal orthopedic implant should provide an excellent bone-implant connection, less implant loosening and minimum adverse reactions. Commercial pure titanium (CP-Ti) and Ti alloys have been widely utilized for biomedical applications such as orthopedic and dental implants. However, being bioinert, the integration of such implant in bone was not in good condition to achieve improved osseointegraiton, there have been many efforts to modify the composition and topography of implant surface. These processes are generally classified as physical, chemical, and electrochemical methods. Plasma electrolytic oxidation (PEO) as an electrochemical route has been recently utilized to produce this kind of composite coatings. Mg ion plays a key role in bone metabolism, since it influences osteoblast and osteoclast activity. From previous studies, it has been found that Mg ions improve the bone formation on Ti alloys. PEO is a promising technology to produce porous and firmly adherent inorganic Mg containing $TiO_2$($Mg-TiO_2$ ) coatings on Ti surface, and the amount of Mg introduced into the coatings can be optimized by altering the electrolyte composition. In this study, a series of $Mg-TiO_2$ coatings are produced on Ti-6Al-4V ELI dental implant using PEO, with the substitution degree, respectively, at 0, 5, 10 and 20%. Based on the preliminary analysis of the coating structure, composition and morphology, a bone like apatite formation model is used to evaluate the in vitro biological responses at the bone-implant interface. The enhancement of the bone like apatite forming ability arises from $Mg-TiO_2$ surface, which has formed the reduction of the Mg ions. The promising results successfully demonstrate the immense potential of $Mg-TiO_2$ coatings in dental and biomaterials applications.

• Journal of Animal Science and Technology
• /
• v.48 no.1
• /
• pp.107-114
• /
• 2006

A total of 180 Arbor Acre broilers (35 days of age) were fed a diet containing 0%, 0.6%, 1.2%, 1.8%, 2.4% or 4.8% conjugated linoleic acid (CLA) for 3 weeks then slaughtered at week 1, 2 and 3. Thigh and breast muscles were seamed out, vaccum-packed prior to storage in a chill for days 7 to analyse thiobarbituric acid reactive substances (TBARS). The accumulation of CLA in breast and thigh muscles was increased significantly (P<0.05) as the CLA level was increased, but no significant difference amongst the treatments. The contents of saturated fatty acids were significantly increased(P<0.05) with an increase of dietary CLA level, but those of unsaturated fatty acids were significantly decreased (P<0.05). The content of mono unsaturated fatty acid (MUFA) was decreased as dietary CLA level increased, even though that of poly unsaturated fatty acid (PUFA) had a little difference between dietary CLA level. Dietary CLA reduced the degree of lipid oxidation in raw chicken meat during storage.

• Korean Journal of Food Science and Technology
• /
• v.20 no.5
• /
• pp.704-710
• /
• 1988

This study was, firstly, to investigate water holding capacity in terms of variation of moisture sorption isotherms of seasoned squid treated with sodium lactate, glycerol, propylene glycol, sorbitol, mannitol, sodium benzoate, potassium sorbate and calcium propionate, and secondly, the effect of humectant treatments on storage stability was studied. The criteria for storage stability was based on three quality factors, namely, lipid oxiations, color development by non-enzymatic browning reactions and lipid oxidation, and mold growth. The effect of humectants on equilibrium moisture content was in the following increasing order; mannitol < sorbitol < sodium lactate < propylene glycol < glycerol. The experimental data indicated that sodium lactate has, in practice, potentially positive effect on processing of seasoned squid. During the storage period of 60 days, TBA values increased in all samples tested as humectants concentrations increased up to 10%. However, in the range of 1-7% sodium lactate treatment, the degree of lipid oxidation, browning reactions and mild growth were not high enough to affect the quality of seasoned squid, when compared with conventionally manufactured ones.

• Journal of Korean Society for Atmospheric Environment
• /
• v.27 no.5
• /
• pp.534-544
• /
• 2011

The secondary aerosol forming potential of ambient air was first measured with the Potential Aerosol Mass(PAM) chamber at Gosan supersite on Jeju island from October 22 to November 5, 2010. PAM chamber is a small flowthrough photo-oxidation chamber with extremely high OH and $O_3$ levels. The OH exposure in the PAM chamber was $(2{\pm}0.4){\times}10^{11}{\sim}(6{\pm}1.2){\times}10^{11}$ molecules $cm^{-3}$ s and was similar to 2 to 5 days of aging in the atmosphere. By periodically turning on and off UV lamps in the PAM chamber, ambient aerosol and newly formed aerosol (e.g. called as PAM aerosol) was alternately measured. Aerosol number and mass concentration in the range of 10~487 nm in diameter was measured by SMPS 3034. With UV lamps on, the nucleation mode particles smaller than 50 nm in diameters were formed. Their number concentration was greater than 105 $cm^{-3}$, leading to increase in aerosol mass by 0~8 ${\mu}gm^{-3}$. The variations of PAM and ambient aerosols were greatly dependent on characteristics of air masses such as precursor concentrations and degree of aging. This preliminary results suggests that PAM chamber is useful to assess the aerosol formation potential of air mass and its impact on the air quality. The further analysis of data with gaseous and particulate measurements will be done.

• Journal of Biomedical Engineering Research
• /
• v.43 no.1
• /
• pp.1-10
• /
• 2022

Non-alcoholic fatty liver disease(NAFLD) is excessive hepatic lipid accumulation mainly caused by obesity. This study aimed to evaluate whether micro-current stimulation(MCS) could modulate lipid metabolism regarding the Sirt1/AMPK pathway, fatty acid β-oxidation pathway, and lipolysis and lipogenesis-related factors in FL83B cells. For the NAFLD cell model, FL83B cells were treated with oleic acid for lipid accumulation. MCS were stimulated for 1 hr and used frequency 10 Hz, duty cycle 50%, and biphasic rectangular current pulse. The intensity of MCS was divided into 50, 100, 200, and 400 ㎂. Through the results of Oil red O staining, it was confirmed that MCSs with the intensity of 200 ㎂ and 400 ㎂ significantly reduced the degree of lipid droplet formation. Thus, these MCS intensities were applied to western blot analysis. Western blot analysis was performed to analyze the effects of MCS on lipid metabolism. MCS with the intensity of 400 ㎂ showed that significantly activated the Sirt1/AMPK pathway, a key pathway for regulating lipid metabolism in hepatocytes, and fatty acid β-oxidation-related transcription factors. Moreover, it activated the lipolysis pathway and suppressed lipogenesis-related transcription factors such as SREBP-1c, FAS, and PPARγ. In the case of MCS with the intensity of 200 ㎂, only PGC1α and SREBP-1c showed significant differences compared to cells treated only with oleic acid. Taken together, these results suggested that MCS with the intensity of 400 ㎂ could alleviate hepatic lipid accumulation by modulating lipid metabolism in hepatocytes.

• Composites Research
• /
• v.35 no.4
• /
• pp.242-247
• /
• 2022

This study has a different direction from the existing technology of applying recycled carbon fiber obtained by recycling waste CFRP to CFRP again. A study was conducted to utilize recycled carbon fiber as a raw material for manufacturing a carbon/carbon (C/C) composite material comprising carbon as a matrix. First, it was attempted to recycle a commonly used epoxy resin composite material through a thermal decomposition process. By applying the newly proposed oxidation-inert atmosphere conversion technology to the pyrolysis process, the residual carbon rate of 1~2% was improved to 19%. Through this, the possibility of manufacturing C/C composite materials utilizing epoxy resin was confirmed. However, in the case of carbon obtained by the oxidation-inert atmosphere controlled pyrolysis process, the degree of oxygen bonding is high, so further improvement studies are needed. In addition, short-fiber C/C composite material specimens were prepared through the crushing and disintegrating processes after thermal decomposition of waste CFRP, and the optimum process conditions were derived through the evaluation of mechanical properties.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.25 no.1
• /
• pp.6-22
• /
• 1999

Chitosan oligosaccharide having physiological activity, such as cell proliferation and wound healing, was prepared by NaNO$_2$ oxidation-NaBH$_4$ reduction from natural chitosan. After deamination by NaNO$_2$ oxidation, the reducing-end residue from NaBH$_4$ was converted to alditol unit, and the reduction was checked by MBTH reagent. The resulting chitosan oligosaccharide had a degree of polymeration of 2-6 from HPLC analysis. From moisture absorption test at relative humidity of 43% and 81%, the moisture absorption ability was 63% and 57%. Moisture retention ability at relative humidity of 43%, silica gel emvironment, was 98% and 97% respectively. Cell proliferation was showed In the range of 0.000032~0.01%, wound healing effect was also appeared in the concentration of 2% and 20%. Antioxidative effect ($SC_{50}$/) was 3213 ppm. Chitosan oligosaccharide was compatible with most of ingredients used in cosmetic products.

• Korean Journal of Food Science and Technology
• /
• v.41 no.6
• /
• pp.628-635
• /
• 2009

Autoxidative stability of wheat bran and germ oil extracted from Keumkang wheat (WBG-K) or Dark Northern Spring wheat (WBG-DNS) at $50^{\circ}C$ in the dark was compared by peroxide values (POV) and fatty acid composition by gas chromatography. Changes of minor compounds were monitored by HPLC. WBG-K showed significantly higher linoleic but lower oleic acid content than WBG-DNS. WBG-DNS contained more phospholipids but less tocopherols and carotenoids than WBG-K. POV of oils was increased during storage, with no significant difference in the oxidation rates between two oils. Tocopherols, carotenoids, and phospholipids in both oils were degraded during the autoxidation. Total phospholipids content showed the highest correlation with the degree of oxidation in WBG oils. The results clearly showed that both fatty acid composition and contents of tocopherols, carotenoids, and phospholipids co-affected the autoxidation of WBG oil.