• Journal of Powder Materials
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• v.23 no.3
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• pp.228-234
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• 2016

Copper nanoparticles attract much attention as substitutes of noble metals such as silver and can help reduce the manufacturing cost of electronic products due to their lower cost and good conductivity. In the present work, the chemical reduction is examined to optimize the synthesis of nano-sized copper particles from copper sulfate. Sodium borohydride and ascorbic acid are used as reducing and antioxidant agents, respectively. Polyethylene glycol (PEG) is used as a size-control and capping agent. An appropriate dose of PEG inhibits the abnormal growth of copper nanoparticles, maintaining chemical stability. The addition of ascorbic acid prevents the oxidation of nanoparticles during synthesis and storage. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) are used to investigate the size of the synthesized nanoparticles and the coordination between copper nanoparticles and PEG. For chemical reduction, copper nanoparticles less than 100 nm in size without oxidized layers are successfully obtained by the present method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.5 no.3
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• pp.207-216
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• 1993

Experimental investigations have been carried out to find the effect of drag reduction caused by effective polymer additives in turbulent flows. The experiments were undertaken with a test section of 9.8mm pipe diameter and 3500 mm pipe length(L/D=357) in a closed loop, and Copolymer-X and Polyacrylamide(PAAM) were used as polymer additives for comparisons. The tests were carried out under different polymer concentrations, and the temperatures of the flow considered were $26^{\circ}C$, $60^{\circ}C$ at the flow velocity of 5.3 m/s. The rate of drag reduction obtained by Copolymer-X is found to be considerably higher than that of PAAM in turbulent flows. Copolymer-X is also found to be very reliable for mechanical degradation, which has not been the case in any other additives. It is concluded that Copolymer-X is considered to be one of the most effective agents as an additive especially for long time hydraulic transports. It is also found that polymer degradation in more likely at lower polymer concentrations in the turbulent flows.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.1
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• pp.55-62
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• 2008

This study is aimed at substantially reducing the particulate matter (dust) emission during the combustion of heavy fuel in boilers by addition of combustion improver. The combustion improver used were the oil-soluble organometallic compounds that were found to be more effective than the dispersing agents that are generally used for reducing the particulate emission. The dust reduction effect was found to depend on the active materials (metals) as well as on the organic ligand part of organometallic compounds. Acetylacetonoate and naphthenate of Fe and Ca were found to be most effective for dust reduction. Addition of Fe and Ca organometallic compounds as combustion improver in concentration of 30 ppm (metal basis) to heavy fuel oil, caused dust reduction by 50 wt% to 80 wt%.

• Restorative Dentistry and Endodontics
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• v.48 no.4
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• pp.39.1-39.23
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• 2023

Objectives: This study aimed to investigate the effectiveness of different topical/systemic agents in reducing the damage caused by bleaching gel to pulp tissue or cells. Materials and Methods: Electronic searches were performed in July 2023. In vivo and in vitro studies evaluating the effects of different topical or systemic agents on pulp inflammation or cytotoxicity after exposure to bleaching agents were included. The risk of bias was assessed. Results: Out of 1,112 articles, 27 were included. Nine animal studies evaluated remineralizing/anti-inflammatories agents in rat molars subjected to bleaching with 35%-38% hydrogen peroxide (HP). Five of these studies demonstrated a significant reduction in inflammation caused by HP when combined with bioglass or MI Paste Plus (GC America), or following KF-desensitizing or Otosporin treatment (n = 3). However, orally administered drugs did not reduce pulp inflammation (n = 4). Cytotoxicity (n = 17) was primarily assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on human dental pulp cells and mouse dental papilla Cell-23 cells. Certain substances, including sodium ascorbate, butein, manganese chloride, and peroxidase, were found to reduce cytotoxicity, particularly when applied prior to bleaching. The risk of bias was high in animal studies and low in laboratory studies. Conclusions: Few in vivo studies have evaluated agents to reduce the damage caused by bleaching gel to pulp tissue. Within the limitations of these studies, it was found that topical agents were effective in reducing pulp inflammation in animals and cytotoxicity. Further analyses with human pulp are required to substantiate these findings.

• Journal of The Korean Society of Grassland and Forage Science
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• v.18 no.2
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• pp.89-94
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• 1998

A field experiment was carried out to determine the effects of chemical drying agents at mowing on the field drying rate of alfalfa (cv. Vernal) and rye (cv. Koolgrazer) for hastening hay manuf8cture. In alfalfa; chemicals ($K_2CO_3$ 2% $K_2CO_3$ 3% $Na_2CO_3$ 2% $CaCO_3$, 2% $K_2CO_3$2% + $Na_2CO_3$, 1% only water spray and control) were treated at early bloom stage in 1995. Chemicals ($K_2CO_3$, 2%, $Na_2CO_3$, 2% $CaCO_3$, 2% and control) were applicated at different harvest stages (early heading, heading and bloom) in rye, 1996. The drying rate of alfalfa by $K_2CO_3$ treatment among chemicals was higher than control, and the duration of field dry was shortened by one day with $K_2CO_3$ application, but there was no difference in drying efficiency between $K_2CO_3$ 2% and $K_2CO_3$ 3%. In rye, however, no moisture reduction by chemicals was observed. The days required for field dry were 6, 4, and 3 days at warly heading heading and bloom stage respectively; regardless of chemical drying agents and conbol. The nutritive value of rye hay with chemicals at baling was very slightly higher than control, but there was no significant difference. Also, no difference of hay quality was found among drying agents. In conclusion, $K_2CO_3$can enhance the field drying rate of alfalfa hay, but the drying efficiency was not high, particularly in rye hay. Harvesting at early heading to heading stage was desirable for manufacture of high quality rye hay.

• 한국약용작물학회:학술대회논문집
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• 2008.05a
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• pp.81-82
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• 2008

• Carbon letters
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• v.24
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• pp.47-54
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• 2017

Different phytochemicals obtained from various natural plant sources are used as reduction agents for preparing gold, copper, silver and platinum nanoparticles. In this work a green method of reducing graphene oxide (rGO) by an inexpensive, effective and scalable method using olive leaf aqueous extract as the reducing agent, was used to produce rGO. Both GO and rGO were prepared and investigated by ultraviolet and visible spectroscopy, Fourier-transform infrared, scanning electron microscopy, atomic force microscopy, thermogravimetric analysis, cyclic voltammetry, X-ray photoelectron spectra, electrochemical impedance spectroscopy and powder X-ray diffraction.

• Journal of the Korea Furniture Society
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• v.19 no.3
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• pp.172-179
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• 2008

The objective of this study was to investigate the influence of the water repellents' treatment on the water absorptivity and the dimensional stability of Korean red pine wood(Pinus densiflora). The alkylketene dimer(AKD), fluororesin emulsion(Wood-seal, WS), and paraffin wax emulsions(PW25, PW40, and PW1200) were used as water repellents. PW40 and WS were proved as excellent water repellents for pine wood, because the samples treated with these agents showed high contact angles and large reduction in water absorptivities. Also, the dimensional stability(antiswelling efficiency) of pine wood was considerably improved by water repellents treatments, such as PW40 and WS at the pressure of 2MPa. The water repellent treated woods with WS, PW40, and PW1200 at the pressure of 2MPa were relatively stable to the wet-dry cyclic leaching test.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.36-41
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• 1996

Drugs mean not only medicines but also poisons, pesticides, food additives, cosmetics, cleaning agents, environmental pollutants and so on, which are normally considered foreign to the body, It is important to know what happens to these drugs when they get into the body. In the past the metabolic changes of drugs had been referred to as “detoxication mechanism”, but since there are many instances in which drugs are converted in the body to more active substances. Thus, metabolism of drugs is responsible for activation and inactivation of the drugs in the body. The major reactions in drug metabolism are oxidation, reduction, hydrolysis and conjugation. Of these four areas, most of the attention had been focused on the oxidation. Therefore, in contract of ample literatures on drug-oxidizing enzymes, there were relatively few reports on drug-reducing enzymes. In recent years, however, the reduction has received an increasing interest due to its pharmacological or toxicological significance. The present lecture is organized keeping with a focus on drug-reducing enzymes which have been explored by us and by other groups.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.119-124
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• 2002

Generally, Portland cement concrete(PCC) pavements have the advantage of durability and superior surface friction when compared to most dense-graded asphalt. However, It is known that PCC pavements create more noise than asphaltic surfaces due to the noise from interaction of tire and pavement surface. Recently exposed aggregate concrete(EAC) pavement was sugested to reduce traffic noise. So in this paper, we considered several materials and mixture proportions for proper depth of exposed aggregate which was measured by the sand patching test, and then according to those relationships, we tried to find out dosage of retarding agents and optimum mixture proportions for expecting good effects to noise reduction. It were also evaluated sound level at every conditions of surface texture as like depth of aggregate exposed, profile peak, distance of aggregate and types of aggregate.