• Journal of Electrochemical Science and Technology
• /
• v.10 no.1
• /
• pp.69-81
• /
• 2019

The corrosion inhibiting mechanism of Vietnam orange peel essential oil (OPEO) for mild steel in 1 N HCl solution was investigated elaborately. Corrosion inhibition ability of OPEO was characterized by electrochemical polarization, electrochemical impedance spectroscopy (EIS), and weight loss method. In the corrosive solution, OPEO worked as a mixed inhibitor and the inhibition efficiency of OPEO increased with the increase of its concentration. High inhibition efficiencies over 90% were achieved for the concentration of 3 - 4 g/L OPEO, comparable to that of 3.5 g/L urotropine (URO), a commercial corrosion inhibitor for acid media used in industry. By using adsorption isotherm models (Langmuir, Temkin and Frumkin), thermodynamic parameters of adsorption were calculated. The obtained results indicated physical adsorption mechanism of OPEO on the steel surface. The components responsible for the corrosion inhibition activity of OPEO were not only D-limonene, but also other compounds, which contain C=O, C=C, O-H, C-O-C, -C=CH and C-H bonding groups in the molecules.

• 한국신재생에너지학회:학술대회논문집
• /
• 2005.06a
• /
• pp.618-621
• /
• 2005

In this study, the phenomena of hydrate formation and inhibition were investigated according to varying the concentrations using methanol and ethylene glycol as chemical additives. The results reveal that the used additives display better inhibition effects compared to pure water by decreasing the formation temperature and the inhibition performance of methanol is superior to that of ethylene glycol. As a conclusion, the plugging phenomena of flowline in natural gas product ion. subsea and frozen field pipelines can be predicted by examining the hydrate formation and inhibition conditions. Specifically, the results of this study can be applied to the selection of the prevention criteria and method of hydrate formation.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.12
• /
• pp.1673-1678
• /
• 2014

The interactive inhibitory effects of pH and chloride on the catalysis of laccase from Trametes versicolor were investigated by studying the alteration of inhibition characteristics of sodium chloride at different pHs for the oxidation of 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid). At pH 3.0, the addition of sodium chloride (50 mM) brought about a 40-fold increase in $K{_m}^{app}$ and a 4-fold decrease in $V_{max}{^{app}}$. As the pH increased to 7.0, the inhibitory effects of sodium chloride became significantly weakened. The mixed-inhibition mechanism was successfully used to quantitatively estimate the competitive and uncompetitive inhibition strengths by chloride at two different pHs (pH 3.0 and 6.0). At pH 3.0, the competitive inhibition constant, $K_i$, was 0.35 mM, whereas the uncompetitive inhibition constant, $K{_i}^{\prime}$, was 18.1 mM, indicating that the major cause of the laccase inhibition by chloride is due to the competitive inhibition step. At a higher pH of 6.0, where the inhibition of the laccase by hydroxide ions takes effect, the inhibition of the laccase by chloride diminished to a great extent, showing increased values of both the competitive inhibition constant ($K_i=23.7mM$) and uncompetitive inhibition constant ($K{_i}^{\prime}=324mM$). These kinetic results evidenced that the hydroxide anion and chloride share a common mechanism to inhibit the laccase activity.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.8
• /
• pp.1891-1892
• /
• 2009

• Bulletin of the Korean Chemical Society
• /
• v.25 no.9
• /
• pp.1297-1298
• /
• 2004

• Korean Journal of Pharmacognosy
• /
• v.43 no.2
• /
• pp.122-126
• /
• 2012

The MeOH extract of Evodiae Fructus exhibited a significant inhibition on the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), in a dose dependent manner, respectively. The extensive bioactivity-guided fractionation process with the MeOH extract finally isolated four compounds, as rutaecarpine (1), evodiamine (2), limonin (3) and dehydroevodiamine (4). Among them, compound 2 exhibited specific inhibitory activity on BChE with the $IC_{50}$ values 1.7 ${\mu}g/ml$, whereas compound 4 showed the potent inhibition upon both AChE and BChE.

• Corrosion Science and Technology
• /
• v.16 no.1
• /
• pp.23-30
• /
• 2017

The inhibition effect of thioureido imidazoline inhibitor (TAI) for flow accelerated corrosion (FAC) at different locations for an X65 carbon steel elbow was studied by array electrode and computational fluid dynamics (CFD) simulations. The distribution of the inhibition efficiency measured by electrochemical impedance spectroscopy (EIS) is in good accordance with the distribution of the hydrodynamic parameters at the elbow. The inhibition efficiencies at the outer wall are higher than those at the inner wall meaning that the lower inhibition efficiency is associated with a higher flow velocity, shear stress, and turbulent kinetic energy at the inner wall of the elbow, as well as secondary flow at the elbow rather than the mass transport of inhibitor molecules. Compared to the static condition, the inhibition efficiency of TAI for FAC was relatively low. It is also due to a drastic turbulence flow and high wall shear stress during the FAC test, which prevents the adsorption of inhibitor and/or damages the adsorbed inhibitor film.

• Korean Chemical Engineering Research
• /
• v.50 no.4
• /
• pp.604-609
• /
• 2012

Properties of fucoidan used for functional cosmetic ingredients and the effect of fucoidan molecular weight on the cosmetic functions were studied. Fucoidan was extracted from Undaria pinnatifida sporophylls and molecular weight (35~160 kDa) of fucoidan was controlled by contact glow discharge electrolysis (CGDE). To test possibility of fucoidan as a cosmetics material, tyrosinase inhibition property, water-holding property, elastase activity inhibition property and DPPH free radical scavenging property were measured. Water-holding property of fucoidan was higher than that of hyaruronic acid, which is known as the one of the best water-holding material. The water-holding strength of fucoidan slightly increase as molecular weight of fucoidan decrease. Elastase activity inhibition (anti wrinkle effect) of fucoidan was higher than that of adenosine using standard material for anti wrinkle test. Optimum molecular weight of fucoidan to obtain highest tyrosin inhibition effect, elastase inhibition effect and radical scavenger effect is 100 kDa.

• The Plant Pathology Journal
• /
• v.16 no.3
• /
• pp.125-129
• /
• 2000

A rapid and efficient assay to determine melanin biosynthesis inhibition of Magnaporthe grisea, a causal agent of the rice blast, by chemicals was developed. Wells in 24-well plates were loaded with spore suspension of the fungus and three known melanin biosynthesis inhibitors of KC10017, tricyclazole, and carpropamid. Subsequent color changes of mycelia and culture media in the wells were observed 7 days after incubation. The wells treated with KC10017 (an inhibitor of polyketide synthesis step and/or pentaketide cyclization step) became colorless, whereas tricyclazole (an inhibitor of 1, 3, 8-trihydroxynaphthalene reductase) or carpropamid (an inhibitor of scytalone dehydratase)-treated wells exhibited red color. They did not show any inhibitory effect on fungal growth. The inhibition of reaction steps prior to 1, 3, 6, 8-tetrahydroxynaphthalene formation was easily determined by colorless medium and mycelia. However, it was impossible to distinguish between inhibition of reduction steps and inhibition of dehydration steps by colors of the cultures. It was accomplished through HPLC analysis of the melanin biosynthesis-involving pentaketide metabolites accumulated by the inhibitors. Through screening of a number of synthetic chemicals using the in vitro assay, we could find a novel chemical group of melanin biosynthesis inhibitor.

• Journal of the Korean Chemical Society
• /
• v.55 no.5
• /
• pp.835-841
• /
• 2011

Corrosion inhibition of mild steel by nevirapine, an antiretroviral has been investigated using potentiodynamic polarization, electrochemical impedance spectroscopy technique and weight loss methods. The experimental results suggested, nevirapine is a good corrosion inhibitor for mild steel in 1M hydrochloric acid medium and the inhibition efficiency increased with increase in inhibitor concentration. The kinetic parameters for corrosion process and thermodynamic parameters for adsorption process were calculated and discussed. The adsorption of the inhibitor on the surface of mild steel followed Langmuir adsorption isotherm.