• Journal of Nutrition and Health
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• v.38 no.4
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• pp.297-306
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• 2005

It is known that dehydroepiandrosterone (DHEA) shows a dual effect, prooxidant or antioxidant, depending on the do-sage or physiological status of animals. The purpose of this study was to determine the effects of DHEA administration at low dose on lipid peroxidation, protein carbonylation and fatty acid composition in liver. Sprague Dawley male rats were fed either com oil diet containing $15\%$ com oil or fish oil diet containing $2\%$ corn oil + $13\%$ sardine oil, with or without $0.2\%$ DHEA for 9 weeks. Atherogenic index and hepatic triglyceride and cholesterol levels were significantly reduced by DHEA administration in rats fed with fish oil diet. Hepatic lipid peroxide product (TBARS) and protein carbonyl levels were significantly higher in rats fed with fish oil diet than in rats fed with corn oil diet. However, DHEA administration significantly reduced the hepatic thiobarbituric acid-reactive substance (TBARS) and conjugated diene levels in rats fed with fish oil diet. Contents of C16 : 0, C16 : 1, C20 : 5 and C22 : 6 in hepatic microsome were higher in rats fed with fish oil diet than in rats fed with corn oil diet, and contents of C18 : 2 and C20 : 4 were lower than in rats fed with com oil diet. DHEA administration significantly increased C16 : 0 and C18 : 3 contents and reduced C18 : 2 content in rats fed with com oil diet, while it increased C16 : 0 and C18 : 1 and reduced C20 : 5 and C22 : 6 in rats fed with fish oil diet. On overall, DHEA administration increased saturated fatty acid (SFA) and reduced polyunsaturated fatty acid (PUFA) in hepatic microsome, thereby PUFA/SFA ratio was significantly (p < 0.0001) reduced without the change of n-3/n-6 ratio. Taken together, low dose of DHEA administration lowered PUFA/SFA ratio in hepatic microsomal membranes and also showed antioxidative effect especially in fish oil-induced highly oxidative stress condition through blocking increases of C20 : 5 and C22 : 6 contents.

• Polymer(Korea)
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• v.32 no.5
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• pp.440-445
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• 2008

The failure mechanism and failure morphology of linear low density polyethylene (LLDPE) tubing under hydrostatic pressure were investigated. Microscopic observations using video microscope and scanning electron microscope indicate that the failure mode is a brittle fracture including cracks propagated from inner wall to outer wall. In addition, oxidation induction time and Fourier transform infrared spectroscopy results show the presence of exothermic peak and the increase in carbonyl index on the surface of fractured LLDPE tubing, due to thermal-degradation. An accelerated life test methodology and testing system for LLDPE tubing are developed using the relationship between stresses and life characteristics by means of thermal acceleration. Statistical approaches using the Arrhenius model and Weibull distribution are implemented to estimate the long-term life time of LLDPE tubing under hydrostatic pressure. Consequently, the long-term life time of LLDPE tubing at the operating temperature of $25^{\circ}C$ could be predicted and also be analyzed.

• Tribology and Lubricants
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• v.37 no.1
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• pp.7-13
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• 2021

Ball bearing is a device that supports and transmits a load acting on a rotating shaft, and it is a type of rolling bearings that uses the rolling friction of the balls by inserting balls between the inner ring and the outer ring. Grease, which is prepared by mixing a thickener with a base oil, is a lubricant commonly used in bearings and has the advantage of a simple structure and easy handling. Bearings are increasingly being used in high value-added products such as semiconductors, aviation, and robots in the era of the 4th industrial revolution. Accordingly, there is an increasing demand for bearing grease. The selection of grease is an important factor in the bearing design. Therefore, a study must be conducted on the grease life evaluation to select an appropriate grease according to operating conditions such as a high temperature, high rotational speed, and high load. In this study, we evaluate the life of ball-bearing grease according to various operating conditions, namely, temperature, speed, and load changes. For this, we develop and theoretically verify a grease life test machine for ball bearings. We conduct a life test of grease according to various operating conditions of bearings and predict the grease life with a 10% and 50% failure probability using the Weibull analysis. In addition, we analyze the oxide characteristics of the grease over time using the Fourier transform infrared spectroscopy and the deterioration characteristics of the grease using the carbonyl index.

• Animal Bioscience
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• v.36 no.8
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• pp.1221-1227
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• 2023

Objective: The present study aimed to investigate the effect of dietary lutein on egg production, follicles, reproductive hormones, fertility, hatchability, and oxidative injury indexes of hens. Methods: Treatments consisted of a control diet (CON) and three lutein-supplementing diets at 25 (L1), 50 (L2), or 75 (L3) mg/kg of diet. Egg production was measured using 576 Arbor Acres breeder hens at 61 to 65 wk and follicles grades, reproductive hormones, fertility, hatchability, tissue lutein contents, and oxidative injury indexes were determined at 65 wk. Results: The results showed that at 65 wk, lutein- supplementing diets increased (p<0.05) egg production, follicular grades, fertility, hatchability, estradiol (E2), luteinizing hormone, progesterone (PROG), lutein content in the serum and yolk, compared to CON. L2 and L3 showed more pronounced (p<0.05) effects on egg production, PROG, and yolk lutein content than L1. With the increase of lutein doses from 25 to 75 mg/kg, there were linear increases (p<0.05) in egg production, lutein content, and PROG, and a quadratic trend (p<0.05) in E2. For the oxidative injury products, lutein-supplementing diets decreased (p<0.05) malondialdehyde (MDA) and protein carbonyl (PCO) in the serum, MDA and 8-hydroxy 2 deoxyguanosine (8-OHdG) in the yolk. There were linear decreases (p<0.05) in 8-OHdG in the serum, MDA, PCO, and 8-OHdG in the yolk, a quadratic trend (p<0.05) on serum 8-OHdG. Conclusion: It is concluded that lutein supplementation can improve egg production and fertility by beneficially regulating reproductive hormones and oxidative status in aged hens.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.24 no.1
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• pp.1-11
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• 2018

In this study, pro-oxidant($d2w^{(R)}$) and rPP/ZnO nanocomposite flexible films for food packaging were prepared, and their mechanical and antimicrobial properties were investigated. As a result, the carbonyl index and hydroxyl index increased with exposured time to heat and UV rays. Surface analysis showed that the addition of zinc oxide improved the dispersibility and compatibility of the polymer, so that the surface of the composite film was smooth and the zinc oxide particles were smaller than the compared film. And it kept the physical properties by heat and UV ray blocking effect, and it worked to reduce decomposition. In the antimicrobial activity test, the microbial reduction rate was 3 logs or more at the use concentration of zinc oxide. The tensile strength was increased and the elongation was decreased. Oxidative degradability of multi-layered film in UV exposured for 72 hours, the molecular weight of the film decreased by 75.6%, 1,294 g/mol Mn and 5,920 g/mol Mw. In the safety analysis of food packaging materials, we obtained that are in standard of polypropylene, a food contact material of domestic law.

• Polymer(Korea)
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• v.38 no.5
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• pp.566-572
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• 2014

Maleic anhydride (MAH) grafted polypropylenes (PP) (MAH-g-PP) were prepared by changing MAH content and styrene monomer (SM)/MAH mole ratio with different type PP, using a twin screw extruder. The types of PP were isotatic PP (iPP), block PP (bPP), and random PP (rPP) and dicumyl peroxide (DCP) was used as an initiator. The graft degree of MAH was confirmed by the existence of carbonyl group (C=O) stretching peak at $3100cm^{-1}$ of FTIR spectrum. Thermal properties of MAH-g-PP and PP/MAH-g-PP/pulp composites were investigated by DSC and TGA. There was no district change in thermal properties of PP/MAH-g-PP/pulp composites. Based on tensile properties and SEM pictures for fractured surface of PP/MAH-g-PP/pulp composites, MAH-g-rPP was the best as the compatibilizer and optimum formulation was MAH content of 1.0 wt%, SM/MAH mole ratio of 1.0, and melt index (MI) of 25 g/10 min. The rheological properties of the composites were investigated by a dynamic rheometer. The complex viscosity, shear thinning effect, and water uptake incresed with pulp content.

• Polymer(Korea)
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• v.37 no.1
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• pp.5-14
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• 2013

In this paper the effect of UV (ultraviolet) exposure on HDPE (high density polyethylene)-smooth and f-PP (flexible polypropylene) geomembranes is evaluated under UVB-313 (ultraviolet wavelength 290-315 nm) exposure. Tensile property, melt flow index (MFI), oxidation induction time (OIT), both standard-OIT and high pressure-OIT and Fourier transform infrared spectroscopy/attenuated total reflectance (FTIR/ATR) results are discussed. Although tensile properties of the exposed geomembrane samples remained unchanged, the depletion of antioxidants was found higher for f-PP than for HDPE geomembrane. Arrhenius model by extrapolation was used on the data to predict the antioxidant lifetime to a typical site temperature of $20^{\circ}C$. There was no significant difference between the MFI value of the virgin and UV exposed HDPE geomembrane samples but a decrease in MFI was found in f-PP geomembrane that signifies that crosslinking has occurred. From FTIR spectra, the small peak (near $1750\;cm^{-1}$) observed in the spectrum of UV exposed sample corresponds to a carbonyl (C=O) linkage, which suggests that oxidation has occurred in the polymer structure, and another new band for f-PP between 3100 and $3500\;cm^{-1}$ is attributed to a hydroxyl bond and/or hydroperoxide bond.

• Food Science and Preservation
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• v.19 no.3
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• pp.420-427
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• 2012

The objective of this research was to investigate the effect of immersion in Rhus verniciflua Stokes extract (RVSE) on the total reducing ability (TRA), protein oxidation and myoglobin oxidation of beef steak (Hanwoo longissimus muscle) stored with high oxygen-modified-atmosphere packaging (MAP) (HOMAP, 75% $O_2$+20% $CO_2$+5% $N_2$) and low oxygen-MAP (LOMAP, 0% $O_2$+20% $CO_2$+80% $N_2$) at $4^{\circ}C$ for nine days. RVSE induced TRA (p<0.05), metmyoglobin (MetMb) formation, and the CIE $H^{\circ}$ value but reduced the carbonyl content and R630-R580, as an index of the intensity of redness by oxymyoglobin, and the CIE $L^*$,$a^*$, and $C^*$ values. HOMAP maintained a lower TRA, MetMb concentration, and CIE $H^{\circ}$ value but had higher R630-R580 and CIE $L^*$, $a^*$, and $C^*$ values compared to LOMAP. Therefore, RVSE induced TRA and protein oxidation stability but reduced myoglobin stability in Hanwoo beef steak. In addition, the effects of HOMAP were opposite those of RVSE.

• Journal of Life Science
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• v.19 no.10
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• pp.1389-1395
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• 2009

Generally, it takes a long time to purify wood vinegar, and it contains toxic compounds such as tar, methanol, phenol and benzopyrene. To reduce the toxicity of wood vinegar itself, we have developed a new purification method of wood vinegar using an oxidation-cohesion reaction and distillation with an active carbon. We have investigated the physico-chemical change (pH, specific gravity, refractive index and dissolved tar), the change of amount of toxic compounds (carbonyl group, phenol, benzopyrene and residual solvents) and organic acids (formic acid (FA), acetic acid (AA), propionic acid (PA)) of the purified wood vinegar under the long term and accelerated storage conditions. Also, we have evaluated the effect of the purified wood vinegar on hair growth using an alopecia model of C57BL/6 mice. As a result, we could find out that the purified wood vinegar was stable and remained without decay under the storage conditions and benzopyrene, a carcinogenic agent, was not detected in the purified wood vinegar. After topical treatment of the purified wood vinegar solution or minoxidil (MXD) for 2 weeks to dorsal skin, the hair regrowth of the mice accelerated faster than that of the control, with no clinical signs. In conclusion, we could suggest a guideline for quality control of process to reduce the toxic compounds in wood vinegar and it might be a useful hair growth promoter in the treatment of baldness or alopecia.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.3
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• pp.685-694
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• 2009

This experimental study was designed to investigate the inhibitory effects of ethanol extract of modified Yukgunja-tang(mYGJT) on high-fat diet-induced obesity and hyperlipidemia in Sprague-Dawley rats, Animals were divided into normal, control, mYGJT(100 mg/kg and 200 mg/kg) treated groups. Obesity with hyperlipidemia was induced by high fat diet treatment for 6 weeks. mYGJT was given to the amimals by oral gavage for 4 weeks, starting at the high-fat diet regimen, The effect of mYGJT on the differentiation of 3T3 L1 adipocytes in vitro and serological paramamters for obesity and hyperlipidemia in vivo were evaluated, mYGJT significnatly inhibited the differentiation of 3T3 L1 adipocytes in a concentration dependent manner. mYGJT treatment siginficantly reduced body weight, abdominal and epididymal fat weight, and FER(Food Efficiency Ratio) compared with control group in a dose dependent manner. It also signficantly inhibited the levels of serum total lipid, triglyceride, phospholipid, total cholesterol, LDL, AI(Atherosclerosis Index) and returned the serum HDL to normal. Total lipids, triglycerides and cholesterols in the liver, as well as malondialdehyde(MDA) and hydroxy radical in the serum were significantly reduced. However, superoxide dismutase(SOD) activity was significantly increased in mYGJT treated group compared with control group. Finally, mYGJT treatment signficantly decreased the MDA and protein carbonyl concentrations of the hepatic homogenate but signficantly increased the activities of SOD, GSH-Px and Catalase. Taken together, these results suggest that mYGJT can be clinically useful in inhibiting high-fat diet-induced obesity and hyperlipidemia.