• Journal of Hydrogen and New Energy
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• v.31 no.3
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• pp.276-283
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• 2020

Alcohol-based solvents including ethanol (EtOH) and tert-butyl alcohol (TBA) are investigated instead of isopropanol (IPA), which is a common solvent for polytetrafluoroethylene (PTFE), as an alternative solvent for preparing the catalyst slurry with PTFE binder. As a result, the performance at 0.2 A/㎠ from the single cells from using catalyst slurries based on EtOH and TBA showed very similar value to that from the slurry using IPA, which implies the EtOH and TBA can be used as a solvent for the catalyst slurry. It is also confirmed by the very close values of the total resistance of the membrane electrode assemblies from the slurries using different solvents. In the energy dispersive spectrometry (EDS) image, the shape of crack and dispersion of PTFE are changed according to the vapor pressure of the solvent.

• Journal of Korea Soil Environment Society
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• v.1 no.1
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• pp.67-79
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• 1996

Clay soils typically have low hydraulic conductivities in the presence of high polarity pore fluid, such as water. Low polarity fluids, such as hydrocarbon fuels and halogenated organic solvents, typically cannot migrate into clay pores because they cannot displace the pore water. Oxygenated additives in gasoline, such as alcohols and methyl-tert-butyl ether, are increasingly used to control air pollution emissions. These relatively polar and highly water-soluble compounds may facilitate displacement of pore water and enhance migration of fuels and solvents through clay-rich soil strata. In the reported research, the migration of gasoline-alcohol fuel mixtures (gasohol) through consolidated clay was examined. Prepared kaolinite clay samples were consolidated from slurry, and various combinations of gasoline, alcohol, and water were applied to the clays under 152 Pa gauge pressure. Movement of the fluids into the clay samples was monitored by measur ing displaced pore fluid and by magnetic resonance imaging of the samples. The structures of selected samples were examined using environmental scanning electron microscopy. Results of the research suggest that alcohol added to hydrocarbon fuels can enhance migration through some clays significantly. Gasoline did not migrate appreciably into water saturated clay, even after 14 days under pressure. The gasohol mixture migrated readily into the clay in only 20 minutes. Increased hydraulic conductivity of the clay in the presence of gasohol is hypothesized to be due to the collapse of the clays pore structure when ethanol is present, creating larger pores. Increasing pore diameter decreases the capillary pressure needed for the gasohol to replace water and allows gasohol to migrate through the clay.

• YAKHAK HOEJI
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• v.50 no.5
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• pp.326-331
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• 2006

We designed and synthesized new benzylpiperidinyl ether derivatives as beta-amyloid aggregation inhibitors for the development of novel anti-Alzheimer's disease agents. As starting material, 4-hydroxypiperidine was used. For protection of the amine group in piperidine (2), di-tert-butyl dicarbonate was reacted with 4-hydroxypiperidine in the presence of triethylamine. For introduction of benzyl group, benzylbromide was treated with compound 2 in dioxane. After deprotection of Boc group on amine in compound 3, ester (5) was synthesized by addition of ethyl-4-chlorobutyrate. The alcohol 6 was synthesized by hydride reduction of 5 using $LiAlH_4$. To obtain final products (7-14), the alcohol 6 was condensed with each of substituted benzoic acids. To screen beta-amyloid aggregation inhibition of the products, thioflavinT assay was performed using $A{\beta}1-42\;at\;37^{\circ}C$ for 26 h incubation, in vitro. From the result of screening, compound 8, 9, 11 and 12 showed effective activity about $65{\sim}85\;{\mu}M\;as\;IC_{50}$ value. Among the prepared compounds, 4-[4-(benzyloxy)piperidino]butyl-4-chlorobenzoate (8) was the most effective inhibitor having $IC_{50}\;of\;65.4{\mu}M$.

• Journal of Soil and Groundwater Environment
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• v.6 no.3
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• pp.31-41
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• 2001

In this study, we have examined the potential degradation of MTBE(methyl tert-butyl ether) by pure culture ENV425 and mixed culture obtained from gasoline contaminated soil using n-butane as the sources of carbon and energy. The results described in this study suggest that MTBE is degraded cometabolically by ENV425 and mixed culture grown on n-butane. Butane and MTBE degradation was completely inhibited by acetylene, which indicated that both substrates were degraded by butane monooxygenase. These cultures grown on n-butane generated TBA (tert-butyl alcohol) as a metabolite of MTBE oxidation. TBA Production was accounted 54.7% and 58.6% for MTBE oxidation by ENV425 and mixed culture, respectively. In resting cell experiments, however, TBA and TBF were detected as the oxidation products of MTBE by ENV425 and mixed culture. The observed maximal MTBE degradation rates were 52.3 and 62.3 (nmol MTBE degraded/hr/mg TSS) by ENV425 and mixed culture, respectively, and the observed maximal transformation yields ($T_y$) were 44.7 and 34.0 (nmol MTBE degraded/$\mu$mol n-butane utilized), and the observed maximal transformation capacities ($T_c$) were 199 and 226 ($\mu$mol MTBE degraded/mg TSS used).

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1693-1698
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• 2012

A headspace gas chromatographic mass spectrometric (GC-MS) assay method was developed for the simultaneous determination of methyl tertiary butyl ether (MTBE), $tert$-butyl alcohol (TBA) and benzene, toluene, ethyl benzene and xylene (BTEX) in soil contaminated with gasoline. 2 g of soil sample were placed in a 10 mL headspace vial filled with 5 mL of phosphoric acid solution (pH 3) saturated with NaCl, and the solution was spiked with fluorobenzene as an internal standard and sealed with a cap. The vial was heated in a heating block for 40 min at $80^{\circ}C$. The detection limits of the assay were 0.08-0.12 ${\mu}g$/kg for the analytes. For five independent determinations at 10 and 50 ${\mu}g$/kg, the relative standard deviations were less than 10%. The method was used to analyze fifty six soil samples collected from various regions contaminated with gasoline in Korea. The developed method may be valuable for the monitoring of the analytes in soil.

• The Korean Journal of Ceramics
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• v.1 no.3
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• pp.152-154
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• 1995

A non-hydrolytic sol-gel process was developed to fabricate low-hydroxyl hard gels. The reaction of tert-butyl alcohol with silicon halides provided transparent low-hydroxyl hard gels. Some properties such as transparency, density, and refractive index was successfully doped into the hard gel matrices. The absorption spectrum of an erbium-doped methylsilsesquioxane was investigated to decide the pumping wavelength of an argon laser. The luminescence of the erbium-doped gel at 664 nm seems to be due to $4^F{9/2}\to 4^I_{15/2}$ transition.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.7 no.2
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• pp.141-146
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• 2021

With increasing interest in fluorinated compounds, nucleophilic fluorination reaction has been generally used for synthesizing fluorine-containing chemicals. However, alkali metal fluorides (MFs) generally have low solubility and reactivity in organic solvent. To overcome these problems, various phase transfer catalysts (PTCs) have been investigated. Calix-arene is known as to capture the metal cation(M⁺), and therefore in this review, we would like to introduce several kinds of calix-arene based PTCs, such as bis-tert-alcohol-functionalized crown-6-calix[4]arene (BACCA), oligo-ethylene glycol linked bis-triethyleneglycol crown-5-calix[4]arene (BTC5A), and ionic liquid functionalized calix-arene based catalyst, as well as ion-pair receptor crown-6-calix[4]arene-capped calix[4]pyrrole.

• The Korean Journal of Ecology
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• v.24 no.3
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• pp.137-140
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• 2001

The antifungal activity of chemical substances from Artemisia annua were examined. Antifungal activity of aqueous extracts from A. annua was higher than that of essential oils in Fusarium oxysporum, whereas that of essential oil was higher than that of aqueous extracts in Aspergillus nidulans. The GC/MS methods were employed for the analysis and identification of phytotoxic substances from A. annua. Essential oil of some components were identified including thujone, terpineol, β-pinene, cienole, 2,4-hexndienal, camphor, citronellal, (-)-menthone, (1R)-(-)myrtenol, (S)-(-)-perilla aldehyde, perilla alcohol, 4-tert-buthylaniline, eugenol, isosafrole, isoeugenol and α-humulene. These results suggest that the chemical substances from A. annua such as terphenoids seem to be responsible for the allelopathic effect.

• Herbal Formula Science
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• v.10 no.2
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• pp.127-141
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• 2002

Objectives: Haeganjeon(HGJ) has been used for the treatment of liver disease in traditional medicine. The present study was carried out to evaluate the antioxidant and protective effects of HGJ extract on oxidative damage of hepatocytes by tert-butyl hydroperoxide(t-BHP). Methods: In the linoleic acid water-alcohol system, the levels of lipid peroxide(LPO) were determined by TBA method. The scavenging effect of HGJ on ${\alpha},{\alpha}-diphenyl-{\beta}-picrylhydrazyl$(DPPH) radical was determined according to the method of Hatano. In the Fenton system(ferrous ion reaction with hydrogen peroxide), the levels of hydroxyl radical induced LPO in rat liver homogenate were determined according to the method of TBA. Inhibitory effect of HGJ on superoxide generation was measured by xanthine-xanthine oxidase system. In order to evaluate antioxidative activity of HGJ in the liver cell, cultured normal rat liver cells(Ac2F) were prepared and incubated with or without HGJ. After 18hr, cells placed in DMEM medium without serum, and then incubated with 1mM tert-butyl hydroperoxide(t-BHP) for 2hrs. Viable cells were detected by MTT assay. Conclusions: In the linoleic acid autoxidation system, HGJ extract significantly inhibited the time course of the lipid peroxidation. These effects were similar to those of BHA HGJ extracts showed about 70% scavenging effect on DPPH radical. And HGJ extract inhibited the lipid peroxide formation in rat liver homogenate induced by hydroxyl radical derived from Fenton system. In addition, HGJ extract protected the cell death induced by t-BHP and significantly increased cell viability in the normal rat liver cell. These result indicated that HGJ extract might playa protective role against oxidative hepatic cell injury by means of free radical scavenger.

• Journal of the Korean Chemical Society
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• v.35 no.1
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• pp.3-15
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• 1991

The gaseous mixtures of iso-propanol of 10 torr with carbon dioxide of 0∼1990 torr were irradiated with Co-60 gamma radiation up to 50 kGy, and the products such as carbon monoxide, acetone, methane, ethane, C$_3$H$_a$, C$_4$H$_b$ and tert-butanol were analyzed by gas chromatography. G(CO) value of 4 was obtained from the gas mixtures containing more than 490 torr of carbon dioxide. The production rates of the organic products and the decomposition rate of iso-propanol increased linearly with the pressure of carbon dioxide, and G(-iso-Propanol) and G(Acetone) values increased by 4 and 2, respectively, with each 10 torr increment of carbon dioxide pressure. The mechanisms of the radiolytic decomposition of iso-propanol and the production of carbon monoxide and organic materials are discussed on the basis of the experimental results of the present study.