• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.399-408
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• 2001

Tooth bleaching has been prevailing recently for its ability to recover the color and shape of natural teeth without reduction of tooth material. However, it has been reported that bleaching procedure adversely affects the adhesive bond strength of composite resin to tooth. At the same time the bond strength was reported to be regained by application of some chemical agents. The purpose of this in vitro study was to investigate the effect of the removal of residual peroxide on the composite- enamel adhesion and also evaluated fracture mode between resin and enamel after bleaching. Sixty extracted human anterior and premolars teeth were divided into 5 groups and bleached by combined technique using of office bleaching with 35 % hydrogen peroxide and matrix bleaching with 10% carbamide peroxide for 4 weeks. After bleaching, the labial surfaces of each tooth were treated with catalase, 70% ethyl alcohol, distilled water and filled with composite resin. Shear bond strength was tested and the fractured surfaces were also examined with SEM. Analysis revealed significantly higher bond strength values. (p＜0.05) for catalase-treated specimens, but water-treated specimens showed reduction of bond strength, alcohol- treated specimens had medium value between the two groups(p＜0.05). The fracture mode was shown that the catalase group and the alcohol group had cohesive failure but the water sprayed group had adhesive failure. It was concluded that the peroxide residues in tooth after bleaching seems to be removed by gradual diffusion and the free radical oxygen from peroxide prevents polymerization by combining catalyst in the resin monomer. Therefore it may be possible to eliminate the adverse effect on the adhesion of composite resin to enamel after bleaching by using water displacement solution or dentin bonding agent including it for effective removal of residual peroxide.

• Environmental Analysis Health and Toxicology
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• v.19 no.1
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• pp.33-40
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• 2004

Benzoyl peroxide is a High Production Volume Chemical, which is produced about 1,371 tons/year in Korea as of 2001 survey. The substance is mainly used as initiators in polymerization, catalysts in the plastics industry, bleaching agents for flour and medication for acne vulgaris. In this study, Quantitative Structure-Activity Relationships (QSAR) are used for getting adequate information on the physical -chemical properties of this chemical. And hydrolysis in water, acute toxicity to aquatic and terrestrial organisms for benzoyl peroxide were studied. The physical -chemical properties of benzoyl peroxide were estimated as followed; vapor pressure=0.00929 Pa, Log $K_{ow}$ = 3.43, Henry's Law constant=3.54${\times}$10$^{-6}$ atm-㎥/mole at $25^{\circ}C$, the half-life of photodegradation=3 days and bioconcentration factor (BCF)=92. Hydrolysis half-life of benzoyl peroxide in water was 5.2 hr at pH 7 at $25^{\circ}C$ and according to the structure of this substance hydrolysis product was expected to benzoic acid. Benzoyl peroxide has toxic effects on the aquatic organisms. 72 hr-Er $C_{50}$ (growth rate) for algae was 0.44 mg/1.,48 hr-E $C_{50}$ for daphnia was 0.07mg/L and the 96hr-L $C_{50}$ of acute toxicity to fish was 0.24mg/L. Acute toxicity to terrestrial organisms (earth worm) of benzoyl peroxide was low (14 day-L $C_{50}$ = > 1,000 mg/kg). Although benzoyl peroxide is high toxic to aquatic organisms, the substance if not bioaccumulated because of the rapid removal by hydrolysis (half-life=5.2 hr at pH 7 at $25^{\circ}C$) and biodegradation (83% by BOD after 21 days). The toxicity observed is assumed to be due to benzoyl peroxide rather than benzoic acid, which shows much lower toxicity to aquatic organisms. One can assume that effects occur before hydrolysis takes place. From the acute toxicity value of algae, daphnia and fish, an assessment factor of 100 was used to determine the predicted no effect concentration (PNEC). The PNEC was calculated to be 0.7$\mu\textrm{g}$/L based on the 48 hr-E $C_{50}$ daphnia (0.07 mg/L). The substance shows high acute toxicity to aquatic organisms and some information indicates wide-dispersive ore of this substance. So this substance is, a candidate for further work, even if it hydrolysis rapidly and has a low bioaccumulation potential. This could lead to local concern for the aquatic environment and therefore environmental exposure assessment is recommended.

• The Korean Journal of Community Living Science
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• v.17 no.3
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• pp.43-53
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• 2006

In order to improve on the stability during the storage of Han-gwa, this study measured peroxide value, AOM test of ginseng and antioxidants added to Han-gwa. 1.2% of ginseng added to Han-gwa consists of moisture (3.37%), protein(1.30%), lipids (11.54%), carbohydrate(82.45%) and ash (1.34%). The hardness of Han-gwa was 257.7 for 1.2% of ginseng added to Han-gwa and 269.8 for Han-gwa without ginseng. The expansion coefficient of Han-gwa including 1.2% of ginseng was 12.9 magnification to Bandegi, indicating that it was inversely proportioned to the amount of ginseng. The induction period of the AOM test according to the concentration of ginseng in Han-gwa was extended to $0.53{\sim}0.83$ of magnification than the test of Han-gwa without ginseng. According to changes in AOM, acid value, peroxide value and thiobarbituric acid value of Han-gwa with various packing materials, PP multilayer film packing was the most effective material for storage of Han-gwa at 30C. 1.2% of ginseng added to Han-gwa and rosemary extract in a panel test was the most effective, and using PP multilayer film packing for Han-gwa was found to be the most useful method.

• Journal of the Korean Applied Science and Technology
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• v.2 no.1
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• pp.19-23
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• 1985

In order to know the quality changes of the fat and oil foods packed in plastics film by the sunlight, we examined the sunlight transmitting rate by the kind of films and measured the acid value and peroxide value according to it. The results obtained were as follows : 1. The sunlight transmitting rate of various films was explained especial permeability under the wavelength of less than 300nm, but it marked a regular form under that of more than 30nm. 2. The vacuum evaporation film with aluminum on the polyester shuts off most of the sunlight, therefore, it has the best effect that keeps the fats and oils off rancidity. 3. The sunlight transmitting rate of the white color printing film drops about 80% as compared with not printing. 4. The preventive power against the rancidity of fats and oils is PET/Al, PET, PE, nylon and OPP film in that order. The changes of peroxide value and acid value were approximately the same as that of the sunlight transmitting rate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.3
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• pp.552-556
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• 2001

The purpose of this study was to investigate the antioxidant effect of aqueous green tea(AGT) on soybean oil. AGT was freeze-dried and 20% of the freeze-dried aqueous green tea powder (AGTP) was added to soybean oil in the quantities of 0.5%, 1% and 5%. Soybean oil without the addition of AGTP was used as a control. Soybean oil with 0.02% butylated hydroxytoluen(BHT) was used as another experimental sample. Each sample was stored at 6$0^{\circ}C$ for 15 days. The oxidation of these samples was determined by measuring the acid value (AV), peroxide value (POV), and thiobarbituric acid (TBA) value. The result showed that the acid values were lowest in 0.02% BHT, followed by the 0.5% AGTP, 1% AGTP, 5% AGTP and finally the control. When AGTP was added, the peroxide value was lower than both the control and 0.02% BHT. The lowest TBA values were in the 0.5% AGTP followed by 0.02% BHT, 1% AGTP, 5% AGTP and the control, respectively. The 5% AGTP (285 min), 1% AGTP (249 min) and 0.5% AGTP (238) demonstrated longer induction periods, compared to the control (204 min) and the BHT (229 min) by Rancimat method.

• Journal of the Korean Applied Science and Technology
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• v.20 no.2
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• pp.141-147
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• 2003

Oxidized polyethylene wax is obtained by oxidation of polyethylene wax and it is composed of various chemicals, e.g., fatty acid, alcohol, ketone and ester. The application of oxidized polyethylene wax is determined by the composition of these chemical substances. In this basic study we observed the basic reaction parameters of time, temperature, oxygen concentration and catalysts on the oxidation reaction of low molecular weight polyethylene(PE wax) by analyzing the acid value, physical and chemical properties of oxidized PE wax to develop a new oxidation process. Acid values are increased with temperature increase in the rage of $150^{\circ}C^{\sim}180^{\circ}C$ but decreased beyond 190$^{\circ}C$. Acid values are also increased with oxygen concentration. As the oxidation reaction proceeds the molecular weight and softening points of oxidation products are decreased by cracking reaction, but the viscosities are increased. To observe the crystallinity of oxidation products SEM experiment was performed. To obtain a high acid-value product in a mild condition, we adopted free radical catalysts and the acid value of the product using catalyst was higher than the product obtained without catalyst in the same reaction condition. The effective initiators were dicumyl peroxide(DCPO), t-butylperoxy-2-ethyl hexanoate(HOPO) and benzoyl peroxide(BPO) having long half-life.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.6
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• pp.737-742
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• 2016

This study examined changes in physicochemical indicators [K-value, lipid peroxide, and thiobarbituric acid reactive substances (TBARS)] in mackerel muscle during refrigerated storage at $4^{\circ}C$. Analyses were conducted every 3 days for 15 days. First, we visually observed changes in the mackerel. After 3 days, there were rapid changes in color and a rotten smell developed. The K-value of mackerel muscle was 4.21, 19.00, 42.13, 51.71, 71.19, and 80.34% on days 0, 3, 6, 9, 12, and 15, respectively; lipid peroxide level also increased, to 5.34, 5.44, 6.59, 7.29, 8.32, and 8.71 nmol/mL, respectively. TBARS increased from day 0 to 6, but did not change significantly after day 6 (0.98, 1.74, 2.73, 2.09, 1.86, and 1.93 mg Eq. malondialdehyde (MDA)/kg, respectively). The changes in K-value and lipid peroxide level demonstrated a loss of value as fresh food after day 6. The freshness of the stored mackerel had decreased by day 6 and mackerel stored for 9 days was less marketable.

• Asian-Australasian Journal of Animal Sciences
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• v.1 no.4
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• pp.195-199
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• 1988

Two experiments were conducted to evaluate the nutritive value of a diet containing 20% alkaline hydrogen peroxide(AHP) treated aspen sawdust for ruminants. In experiment 1, sheep fed treated aspen(treated) had higher (p < 0.05) average daily gain and improved feed/gain ratio compared to animals fed untreated aspen (untreated), Apparent NDF and ADF digestibilities of treated aspen were higher (p < 0.05) than for untreated material. A similar trend was observed for DM, organic matter and cellulose digestibilities coefficients. In experiment 2, the soluble and degradable DM and crude protein (CP) fractions tended to increase with AHP treatment. Treatment also increased (p<0.05) the degradation rate of the degradable fraction. Results of these experiment indicate that AHP treatment results in a substantial improvement in the extent of utilization of aspen sawdust by ruminants.

• The Korean Journal of Food And Nutrition
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• v.9 no.2
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• pp.137-142
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• 1996

To develop antioxidant substances in plant, phenolic compounds in Bangah (Igodon japonicus, Hara) and antioxidative effects of cell extracts were investigated. Defatted samples of Bangah were extracted with acetone/methanol and the extracts were fractionated Into the free and bound types of phenolics. The equal amounts of fractions were dissolved In soybean oil and autoxidized at 45$^{\circ}C$ for 25 days. Peroxide value and TBA values were determined every 5 days during oxidation. Changes of peroxide and TBA values showed antioxidant effects, which were lower than control during the oxidation periods. The effects of cell extracts were evaluated as high as BHT, 0.02 ppm. The antioxidative effect of insoluble-bound phenolic extract was higher than that of free. The contents of phenolic compounds in insoluble-bound fraction were also higher than free fraction.

• Horticultural Science & Technology
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• v.33 no.3
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• pp.383-389
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• 2015

Chitooligosaccharide (COS), as antioxidant, extensively applied to food and juice preservation. In the present study, influences of COS on vase life and ornamental value of cut roses were investigated. Results showed that vase life of cut roses treated by COS was longer 6.4 days than one of control and ornamental character of cut roses was improved effectively by COS. The increase of vase life and ornamental value were chiefly governed by that COS improved water absorption capacity of cut roses. Besides that, COS decreased the contents of superoxide anion and hydrogen peroxide and lowered the levels of malondialdehyde in turn during the senescence process of cut roses. That was because that COS not only enhanced activities of antioxidant enzymes glutathione reductase, but also improved reduced glutathione contents in petals of cut rose. Therefore, COS could be used in commercial preservatives to improve the longevity of cut roses.