• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.35-38
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• 2012

Room temperature oxidation of organic sulfides with polyvinylpyrrolidone-supported hydrogen peroxide (PVP-$H_2O_2$) in the presence of Mn(III) complexes of meso-tetraphenylporphyrin, Mn(TPP)X (X = OCN, SCN, OAc, Cl) and imidazole (ImH) leads to the highly chemoselective (ca. 90%) oxidation of sulfides to the corresponding sulfoxide. The efficiency of reaction has been shown to be influenced by different reaction parameters such as the nature of counterion (X) and solvent as well as the molar ratio of reactants. Using Mn(TPP)OCN and ImH in 1:15 molar ratio and acetone as the solvent leads to the efficient oxidation of different sulfides.

• Advances in aircraft and spacecraft science
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• v.4 no.1
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• pp.21-35
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• 2017

Hydrogen peroxide is being considered as a monopropellant in micropropulsion systems for the next generation of miniaturized satellites ('nanosats') due to its high energy density, modest specific impulse and green characteristics. Efforts at the University of Vermont have focused on the development of a MEMS-based microthruster that uses a novel slug flow monopropellant injection scheme to generate thrust and impulse-bits commensurate with the intended micropropulsion application. The present study is a computational effort to investigate the initial decomposition of the monopropellant as it enters the catalytic chamber, and to compare the impact of the monopropellant injection scheme on decomposition performance. Two-dimensional numerical studies of the monopropellant in microchannel geometries have been developed and used to characterize the performance of the monopropellant before vaporization occurs. The results of these studies show that monopropellant in the lamellar flow regime, which lacks a non-diffusive mixing mechanism, does not decompose at a rate that is suitable for the microthruster dimensions. In contrast, monopropellant in the slug flow regime decomposes 57% faster than lamellar flow for a given length, indicating that the monopropellant injection scheme has potential benefits for the performance of the microthruster.

• Journal of Environmental Health Sciences
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• v.39 no.3
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• pp.279-288
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• 2013

Objectives: Effectiveness and conditions of vapor-phase hydrogen peroxide (VPHP) system on decontamination of Geobacillus stearothermophilus(GS) spores, Escherichia coli (E.coli) and Enterobacteria phage felix01 (felix01) were determined. Methods: The VPHP system was designed to vaporize 35% (w/w) solution of hydrogen peroxide, continuously to inject and withdraw VPHP. The system and VHP 1000ED (Steris) were operated such that dehumidification and conditioning were initiated without samples in the chamber. Then the samples were loaded into and removed. Coupons (glass, anodizing, silicon, viton) with GS spores ($1{\times}10^6$ colony forming unit/mL [CFU/mL]), E.coli ($1{\times}10^7$ CFU/mL) and felix01 ($1{\times}10^7$ plaque forming unit/mL[PFU/mL]), and Biological Indicator (BI) with GS spores ($1{\times}10^6$ CFU/mL) on stainless steel coupons were used. The tested samples were sonicated and vortexed, and then were plated for enumeration, followed by incubation at $55^{\circ}C$, 24 hr for GS spores, and at $37^{\circ}C$, 24 hr for E.coli and felix01. BI analysis in broth culture was only qualitative. Results: The efficacy of the VPHP system on decontamination was almost equivalent to that of VHP 1000ED. The conditions for complete decontamination with the VPHP system was as follows: concentration; 700~450 ppm, relative humidity; approximately 55%, and temperature; $34{\sim}32^{\circ}C$. When comparing the decontamination efficiency among different kinds of coupons, glass was the most effective, however, all kinds of coupons were decontaminated completely after 60 min exposure in both systems. Conclusion: The VPHP system can be recommended as an alternative system for traditional system using ethylene oxide, formaldehyde or chlorine dioxide.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2000.11a
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• pp.15-21
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• 2000

In chlorine dioxide delignification and bleaching the formation of chlorate is undesirable because it does not react with lignin and is harmful to the environment. Chlorate is mainly formed from the in-situ generated hypochlorus acid which is also the main reason for AOX formation. In previous literature scavengers of hypochlorous acid such as sulfamic aicd, DMSO, and hydrogen peroxide have been added to bleaching stages to reduce AOX formation but less attention has been paid to chlorate reduction. This paper thus focuses on the reduction of chlorate content caused by the following additives, sulfamic acid, DMSO, hydrogen peroxide, and oxalic acid. The results show that only sulfamic acid and DMSO reduce chlorate formation under our chlorine dioxide prebleaching conditions. Results by UV spectroscopy and pH adjustment show that scavengers react with hypochlorous acid much faster than with chlorine. Hydrogen peroxide and oxalic acid react with HClO/$Cl_2$much slower than DMSO and sulfamic acid do. The reason for the ineffectiveness of hydrogen peroxide and oxalic acid is ascribed to their slow reaction rates with HClO compared to that of chlorate formation. The fact that only 30-35% of the chlorate can be reduced by sulfamic acid and DMSO when charged in same mole ratio to chlorine dioxide, suggested that the reaction rate of DMSO and sulfamic acid with hypochlorous aicd are of the same magnitude as that of chlorate formation.

• Polymer(Korea)
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• v.35 no.5
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• pp.444-450
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• 2011

A high molecular weight natural sodium alginate (HMWSAs) was depolymerized by hydrogen peroxide ($H_2O_2$) with ultrasonic irradiation. The effects of the reaction conditions such as reaction temperature, reaction time, hydrogen peroxide concentration and ultrasonic irradiation time on the molecular weights and the end groups of the depolymerized alginates were investigated. It was revealed that depolymerization occurred through the breakage of 1,4-glycosidic bonds of sodium alginate and the formation of formate groups on the main chain under certain conditions. The changes in molecular weight were monitored by GPC-MALS. The molecular weight of 2 wt% alginate solution decreased from 450 to 15.9 kDa for 0.5 hrs at 50 $^{\circ}C$ under an appropriate ultrasonic irradiation. The PDI(polydispersity index)s of the alginate depolymerized in this study were considerably narrow in comparison with those obtained from the other chemical degradation method. The PDIs were in the range of 1.5~2.5 in any reaction conditions employed in this study.

• Bulletin of the Korean Chemical Society
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• v.35 no.9
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• pp.2630-2634
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• 2014

The surface of natural graphite was modified by the use of hydrogen peroxide and evaluated as an anode material for lithium ion capacitors (LICs). The surface treatment was carried out under various ultrasonic conditions of 200, 300, and 400W, which were applied to a mixture of natural graphite and hydrogen peroxide solution for 1 h. While the bulk structure was maintained, the hexagonal symmetry and physical properties of natural graphite, such as BET surface area, tap density, and particle size, were affected by the surface treatment. FT-IR and XPS measurements confirmed the signature of C=O on the surface of graphite samples after treatment. Both the pristine and surface-treated graphites showed a similar reversible capacity of $370mAhg^{-1}$, and the coulombic efficiency of surface-treated graphite decreased with higher ultrasonic energies (89.1%, 89.0%, and 88.0% for 200, 300, and 400 W) comparing with pristine graphite (89.4%). The capacity retention of LICs was greatly improved with the treated natural graphite. The graphite treated under the ultrasonic energy of 300 W and pristine natural graphite showed capacity retention of 77.5% and 42.9%, implying that the surface treatment was an effective method for the improvement of natural graphite as an anode material for LICs.

• Korean Journal of Pharmacognosy
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• v.44 no.3
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• pp.263-268
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• 2013

The protective role against oxidative stress under cellular system using C6 glioma cells was studied using the ethyl acetate (EtOAc) fraction, luteolin (1), and luteolin-7-glucoside (2) of Taraxacum coreanum. C6 glioma cells showed low cell viability and high generation of reactive oxygen species (ROS) by the treatment with generator of hydrogen peroxide ($H_2O_2$) and amyloid beta ($A{\beta}_{25-35}$). However, the treatment of the EtOAc fraction attenuated the cellular oxidative stress, resulting in significant elevation of cell viability. In addition, the production of ROS formation was also decreased by the treatment of the EtOAc fraction. Compounds 1 and 2 were isolated from the EtOAc fraction, and the protective effect was evaluated. Compounds 1 and 2 led to the increase of cell viability and decrease of production of ROS against oxidative stress by $H_2O_2$ and $A{\beta}_{25-35}$. The present study indicated that the EtOAc fraction, compounds 1 and 2 from T. coreanum demonstrated protective effects against oxidative stress, suggesting the preventive role against neurodegenerative diseases.

• Journal of Korean society of Dental Hygiene
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• v.13 no.5
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• pp.901-908
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• 2013

Objectives : The purpose of this study was to evaluate the bleaching effect of 3% hydrogen peroxide containing strip with primer in vivo. Methods : 22 female subjects aged from 20 to 39 years old were recruited after informed consent. They were divided into two groups with control and experimental group. Experimental group was bleached with 3% HP strip with primer, and control group received placebo for 14 days. Color changes were measured with Shade Eye-NCC (Shade Eye-NCC, SHOFU Co., Japan), Shade guide (VITA classical shade guide, $VIDENT^{TM}$, CA, USA) and digital camera image. All collected data were analyzed using SPSS 18.0. Results : At baseline, $L^*$ was $71.75{\pm}3.2$ and $b^*$ was $14.90{\pm}3.6$ in control, and $L^*$ was $71.3{\pm}3.4$ and $b^*$ was $15.61{\pm}3.7$ in experimental group. At day 14, $L^*$ was $71.35{\pm}3.2$ and $b^*$ was $13.97{\pm}4.3$ in control, and $L^*$ was $73.51{\pm}2.0$, $b^*$ was $9.10{\pm}3.0$ in experimental group. ${\Delta}E^*$ of all teeth were statistically significant between the two groups. Final ${\Delta}E^*$ was $7.15{\pm}2.09$ at experimental group and $2.78{\pm}2.93$ at control group, and the difference was significant (p<0.005). Color changes using shade guide also significantly decreased at 14th day compared with baseline at experimental group (p<0.005). Conclusions : 3% hydrogen peroxide strip with primer revealed effective enough to bleaching the human enamel during 14 days without any soft and hard tissue irritations.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.5
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• pp.524-529
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• 2006

Chemical compounds, hydrogen peroxide and nitrite-scavenging activities of Phellinus baumii (PB) were investigated to expand the utilization of PB as functional food material. Total mineral contents of PB was 534.3 mg% and potassium was the highest content being 224 mg%. Total and reducing sugars were 56.2% and 9.8%, respectively The contents of free amino acids (FAAs) were in a range of $16.9{\sim}765.5mg%$ with the major FAAs of phenylalanine, aspartic acid, glutamic acid, leucine, serine and valine. The contents of total phenolic compounds in methanol and hot water extracts of PB were 33.3 and 20.7 mg/100 mL, respectively and were higher than those of other solvent extracts. Hydrogen peroxide-scavenging activity (80%) of methanol extract at $10{\mu}g/mL$ for 30 min was similar to tocopherol (83.1%) as control. Nitrite-scavenging activity of extracts of methanol and hot water at 500 mg/mL and pH 1.2 were 57.3% and 51.8%, respectively and then their effects were increased by lowering pH. The present results showed that the methanol and water extracts of Phellinus baumii exhibited strong hydrogen peroxide and nitrite-scavenging activities.

• Restorative Dentistry and Endodontics
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• v.35 no.1
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• pp.40-50
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• 2010

This study evaluated the efficacy of an office bleaching gel (RemeWhite, Remedent Inc., Deurle, Belgium) containing 30% hydrogen peroxide. 31 volunteers were recieved office bleaching with the RemeWhite for 3 times at one visit, total 2 visits. As control group, the same gel in which hydrogen peroxide was not included was applied to 31 volunteers with the same protocol. The shade change (${\Delta}E^*$, color difference) of 12 anterior teeth was measured using Colorimerter and Vitapan classical shade guide. The shade change of overall teeth in the experimental group was significantly greater than that in the control group which was measured using Colorimeter. There was also a significant difference between baseline and 14 weeks or 26 weeks though color rebounding phenomenon occurred as time went by. Small shade change difference can be measured accurately using Colorimeter than using Vitapan classical shade guide.