Monitoring the gasification area and its behavior in underground coal gasification by acoustic emission technique instead of temperature measurement.

Underground Coal Gasification (UCG) requires monitoring of the gasification area because the gasification process is invisible and the reaction temperature exceeds 1000 °C. Many fracturing events that occurred due to coal heating can be captured with Acoustic Emission (AE) monitoring technique during UCG. However, the temperature conditions to generate fracturing events during UCG have not yet been clarified. Therefore, the coal heating experiment and small-scale UCG experiment are conducted by measuring the temperature and AE activities in this research to examine the applicability of the AE technique instead of temperature measurement as a monitoring method during UCG. As a result, many fracturing events are generated when the temperature of coal is changed drastically, especially during coal gasification. Besides, AE events increase in the sensor near the heat source and AE sources are expanded widely with the expansion of the high-temperature region. AE monitoring is an effective technique for the estimation of the gasification area during UCG instead of temperature monitoring.

Tetrahydro-beta-carboline derivatives in aged garlic extract show antioxidant properties.

This study used the hydroden peroxide scavenging assay to investigate antioxidant chemical constituents derived and separated from aged garlic extract, a unique garlic extract produced by soaking sliced garlic in an aqueous ethanol solution for >10 mo. Four types of 1, 2, 3, 4-tetrahydro-beta-carboline derivatives (THbetaCs); 1-methyl-1, 2, 3, 4-tetrahydro-beta-carboline-3-carboxylic acid, and 1-methyl-1, 2, 3, 4-tetrahydro-beta-carboline-1, 3-dicarboxylic acid (MTCdiC), from both diastereoisomers, were isolated and identified by use of liquid chromatography-mass spectrometry. All these compounds indicate strong hydrogen peroxide scavenging activities and inhibit 2, 2'-azobis(2-amidinopropane) hydrochloride-induced lipid peroxidation. Particularly, (1S, 3S)-MTCdiC had the most potent hydrogen peroxide scavenging activity, more than ascorbic acid. The (1R, 3S)- and (1S, 3S)-MTCdiC at 50-100 micromol/L and 10-100 micromol/L inhibited LPS-induced nitrite production. Interestingly, THbetaCs were not detected in raw garlic and other processed garlic preparations, but they were generated and increased during the natural aging garlic extraction process. These data suggest that THbetaCs, which are formed during the natural aging process, are potent antioxidants in aged garlic extract and thus may be useful for the prevention of diseases associated with oxidative damage.

Hydroponic cultivation offers a practical means of producing selenium-enriched garlic.

Garlic enriched by selenium (Se) could be an excellent source of dietary Se for cancer chemoprevention. The production of high-Se garlic requires Se-fertilized soil, but such soil may pollute the environment. Hydroponics is a closed system that allows good control over Se fertilization without environmental consequences. We examined the effect of hydroponic cultivation on Se uptake and assimilation in garlic seedlings. Garlic bulbs were grown in the nutrient solution without Se for first 2 wk, and with potassium selenate for an additional week. Sulfate in an ordinary hydroponic solution inhibited the absorption and assimilation of selenate, but when a sulfate-free nutrient was used for Se addition, the garlic seedlings accumulated >1 mg Se, dry weight. Through HPLC inductively coupled plasma MS (HPLC-ICP-MS) analysis, Se-methlyselenocysteine (MeSeCys), gamma-glutamyl-Se-methlyselenocysteine (gamma-GluMeSeCys), selenomethionine, and nonmetabolized selenate were identified in water extracts of the garlic seedlings. The results demonstrate that hydroponic enrichment of Se in garlic seedlings could be a practical means of producing organic Se compounds for nutritional supplements.

Identification of six phenylpropanoids from garlic skin as major antioxidants.

The extract of garlic skins (peels) showed strong antioxidant activity, and some responsible constituents were isolated and identified. Garlic (Allium sativum L.) has been used as an herbal medicine, but there is no report on the health benefits of the skin or peel. In this study, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of garlic skin extract was evaluated. Using chromatographic techniques, the active constituents were isolated and subsequently identified. Analyses by high-performance liquid chromatography coupled with a photodiode array detector (HPLC-PDA) suggested that these compounds were phenylpropanoids, which had a characteristic absorbance at 300-320 nm. Liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance analyses allowed the chemical structures of the isolated constituents to be postulated. The proposed compounds were subsequently synthesized and compared with the constituents in the extract using HPLC-PDA and LC-MS. N-trans-Coumaroyloctopamine, N-trans-feruloyloctopamine, guaiacylglycerol-beta-ferulic acid ether, and guaiacylglycerol-beta-caffeic acid ether were identified as were trans-coumaric acid and trans-ferulic acid. Also, the antioxidant activities of these compounds were determined.

Antioxidant effects of tetrahydro-beta-carboline derivatives identified in aged garlic extract.

1,2,3,4-Tetrahydro-beta-carboline derivatives (THbetaCs) are formed through Pictet-Spengler chemical condensation between tryptophan and aldehydes during food production, storage and processing. In the present study, in order to identify the antioxidants in aged garlic extract (AGE), we fractionated it and identified four THbetaCs; 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acids (MTCC) and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-1,3-dicarboxylic acid (MTCdiC) in both diastereoisomers using liquid chromatography mass spectrometry (LC-MS). Interestingly, these compounds were not detected in raw garlic, but the contents increased during the natural aging process of garlic. In in vitro assay systems, all of these compounds have shown strong hydrogen peroxide scavenging activities. (1S, 3S)-MTCdiC was found to be stronger than the common antioxidant, ascorbic acid. MTCC and MTCdiC inhibited AAPH-induced lipid peroxidation. Both MTCdiCs also inhibited LPS-induced nitrite production from murine macrophages at 10-100 microM. Our data suggest that these compounds are potent antioxidants in AGE, and thus may be useful for prevention of disorders associated with oxidative stress.