• Journal of the Korean Wood Science and Technology
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• v.28 no.3
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• pp.52-61
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• 2000

Black locust(Robinia pseudoacacia) and poplar(Populus alba ${\times}$ glandulosa) trees were collected, extracted with acetone-$H_2O$(7:3, v/v) after drying, fractionated with hexane, chloroform and ethylacetate, and freeze dried to get some brown powder. Each fraction of the powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-hexane mixture as eluting solvents. The wood extractives of black locust contained (+)-leucorobinetinidin as flavan, robtin as flavanone and dihydrorobinetin as flavanonol, and robinetin as flavonol. The poplar bark extractives contained various kinds of phenolic compounds : (+)-catechin as flavan, naringeoin, eriodictyol, sakuranetin, aromadendrin and taxifolin as flavanonol, salireposide as salicin derivative, and minor compounds such as aesculin and p-coumaric acid. However, aesculin has not been reported as a constituent of the poplar bark in Korea yet. NMR and FAB-MS analyses were done to elucidate the structures of isolated phenolic constituents.

• Journal of the Korean Wood Science and Technology
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• v.28 no.3
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• pp.62-69
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• 2000

The bark of ash(Fraxinus rhynchophylla) and elm(Ulmus davidiana var. japonica) trees were collected, extracted with acetone-$H_2O$(7:3, v/v), fractionated with hexane, chloroform and ethylacetate, and freeze dried to give some dark brown powder. Each fraction of the powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-hexane mixture as eluents. The ash bark contained a large amount of coumarin derivatives such as aesculetin and aesculin in addition to trace amount of ligstroside and oleuropein. Most of the elm bark extractive were (+)-catechin and its glycosides such as (+)-catechin-7-O-xylopyranose and (+)-catechin-7-O-apiofuranose in addition to a small amount of procyanidin B-3, a dimeric (+)-catechin. NMR and FAB-MS spectrometric analyses were performed to characterize the structures of isolated phenolic compounds.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.3
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• pp.244-249
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• 2011

A sensitive and rapid high-performance liquid chromatographic-tandem mass spectrometric (HPLC/MS/MS) assay was developed for the determination of soyasaponins in soybean. Among soyasaponins, soyasaponin I was isolated and characterized from methanol extracts of soybean as analytical standards and the development of a new analytical procedure for quantification of its content in various cultivars. The structures of these compound was elucidated by $^1H$, $^{13}C$ NMR experiments and by mass spectrometric analysis. Aqueous ethanol extracts of soybean samples were injected on an Agilent XDB-C18 column ($4.6mm{\times}50mm$, $1.8{\mu}m$) with a mobile phase consisting of 10 mM ammonium acetate-acetonitrile, a flow rate of 0.3 mL/min and a total run time of 8 min. Detection was performed by mass spectrometer bin the multiple reaction monitoring (MRM) mode with negative electrospray ionization (ESI) m/z at 941 ${\rightarrow}$ 615 for soyasaponin I. In the 9 soybean samples, contents of soyasaponin I ranged from 205 to 726 mg/kg, and correlated negatively with seed size.

• Korean Journal of Food Science and Technology
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• v.45 no.4
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• pp.501-507
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• 2013

We evaluated the effects of temperature, time, solvent type, and solvent concentration on the phenolic content and antioxidant activity of rosemary extracts. The antioxidant capacity of rosemary extracts was demonstrated by their ability to scavenge stable free radicals, and the phenolic content of the extracts was determined using the Folin Ciocalteu method. The highest values were obtained by water-based extraction at $90^{\circ}C$ for 30 min, a 75% methanol solution at $60^{\circ}C$ for 30 min, and a 50% ethanol solution at $70^{\circ}C$ for 10 min. The aqueous solution of 75% methanol, extraction temperature of $60^{\circ}C$, and extraction time of 30 min were the most efficient parameters for the extraction of polyphenols from dry rosemary.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3269-3273
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• 2009

In this study, recycling methods of nano $TiO_2$-coated silica-bead were conducted in order to solve a deactivation problem of bead that had been invented for decomposition of pollutants in aqueous solution. Surface cleansing was selected as the recycling method for used beads. The surface cleansing was done with four different solutions such as distilled water, surfactant, acetone, and ethyl alcohol(ethanol). The recycling process consists of cleansing and calcination. After cleaning the used (deactivated) beads, calcination was done at $100^{\circ}C$, $200^{\circ}C$ and $300^{\circ}C$ for 30 minutes, respectively. This process was repeated three times. The activity of the recycled bead was measured by photo-degradation of methylene blue. The result shows that acetone cleansing and calcination at $100^{\circ}C$ for 30 minutes was the most efficient recycling method.

• Journal of Sensor Science and Technology
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• v.24 no.3
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• pp.151-154
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• 2015

The gas sensing characteristic of $MoS_2-MoO_2$ composite yolk-shell spheres were investigated. $MoO_3$-carbon composite spheres were prepared by ultrasonic spray pyrolysis of aqueous droplets containing Mo-source and sucrose in nitrogen, which were converted into $MoO_3$ yolk-shell spheres by heat treatment at $400^{\circ}C$ in air. Subsequently, $MoS_2-MoO_2$ composite yolk-shell spheres were prepared by the partial sulfidation of $MoO_3$. The $MoS_2-MoO_2$ composite yolk-shell spheres showed relatively low and irreversible gas sensing characteristics at < $200^{\circ}C$. In contrast, the sensor showed high and reversible response (S=resistance ratio) to 5 ppm $NO_2$ (S=14.8) at $250^{\circ}C$ with low cross-responses (S=1.17-2.13) to other interference gases such as ethanol, CO, xylene, toluene, trimethylamine, $NH_3$, $H_2$, and HCHO. The $MoS_2-MoO_2$ composite yolk-shell spheres can be used as reliable sensors to detect $NO_2$ in a selective manner.

• Journal of the Korean Chemical Society
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• v.39 no.1
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• pp.40-46
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• 1995

A new analytical luminescence method for the Tb+3 and Eu+3 ions was studied using the fluorescence enhancement of the ions on the TLC plate. Compared to the specific emission intensities of the ions in aqueous or ethanol solution, if spotted on the TLC plate, the line intensities were extremely enhanced. There was additional enhancement effect of the lines from the ions on the TLC plate, if treated with ο-phenanthroline. Based on the luminescence enhancement, the detection limit of the ions was lowered more than 6 order of magnitude compared to the luminescence method using solution samples. The energy-transfer mechanism was also explained for the theoretical back ground of the luminescence enhancement.

• Polymer(Korea)
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• v.27 no.6
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• pp.542-548
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• 2003

Nanoparticles with unsaturated poly(hydroxyalkanoate)s (UPHAs) biosynthesized with Pseudo-monas oleovorans were prepared by spontaneous emulsification solvent diffusion method. The influence of nanoparticle formation was investigated with various experimental parameters such as sonication conditions, sol-vent, surfactant and polymer contents, etc. The physical and chemical properties of UPHAS and its nanoparticles were characterized using $^1$H- and $\^$13/C-nuclear magnetic resonance spectroscopies, attenuated total reflection infrared spectroscopy, differential scanning calorimetry and gel permeation chromatography. The morphology of particles was observed using scanning electron microscope and the size and distribution of nanoparticles were measured with electrophoretic light scattering spectrophotometer. The mean diameter of particles decreased with increasing sonication amplitude and time. The addition of ethanol into UPHAS chloroform solution decreased the particle size presumably due to increased solvent diffusion into water phase. The particle size increased with increased the concentration of UPHAS solution. Under the 2-4％ poly(vinyl alcohol) (PVA) aqueous solution the minimum mean diameter of particles was shown. The higher degree of hydrolysis and degree of polymerization of PVA increased the mean diameter of particles.

• Korean journal of food and cookery science
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• v.22 no.6 s.96
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• pp.905-913
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• 2006

The properties of water soluble powder of propolis(WSP), made with different levels(0, 20, 40, 60, 80%) of ethanol extract of propolis(EEP) and hydrocolloid were investigated, along with the quality changes of its bread after 7 days' of storage at $30^{\circ}C$ The yield of WSP containing 40% EEP treated at $160^{\circ}C$ was the highest at 59.3% and the brown color of all the powders tended to be darkened with increasing EEP content. The turbidity of WSP treated at higher temperature was decreased in its aqueous solution (10%, w/w), and this was considered to be due to the presence of minute nonsoluble particles. Antioxidative activities determined by DPPH(1,1-diphenyl-2-picrylhydrazyl) were the lowest in WSP treated at $140^{\circ}C$, while those of the WSP samples prepared at 160 and $180^{\circ}C$ were as high as that of WSP containing more than 40% EEP, regardless of EEP concentration. The propolis breads with added WSP made at $160^{\circ}C$ were selected as the most desirable powder for subsequent study. Bread with WSP40 was the heaviest while the volume loss of WSP80 was the greast after baking. The moisture contents of the propolis bread were drastically decreased until 3 days' of storage, but it was thought that WSP might be ineffective for the prevention of moisture loss. The pH of breads without EEP was decreased after 3 days' of storage, while that of the WSP breads remained almost unchanged until 5 days' of storage. Total bacterial counts also exhibited decay levels during the storage. In conclusion, water soluble powder of propolis is useful as a natural antioxidative and antibacterial material in various types of food.

• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.942-952
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• 2013

Monoliths are functional porous materials with a three-dimensional continuous interconnected pore structure in a single piece. A monolith with uniform shape based on poly(${\gamma}$-glutamic acid) (PGA) has been prepared via a thermally induced phase separation technique using a mixture of dimethyl sulfoxide, water, and ethanol as solvent. The morphology of the obtained monolith was observed by scanning electron microscopy and the surface area of the monolith was evaluated by the Brunauer Emmett Teller method. The effects of fabrication parameters such as the concentration and molecular mass of PGA and the solvent composition have been systematically investigated. The PGA monolith was cross-linked with hexamethylene diisocyanate to produce the water-insoluble monolith. The addition of sodium chloride to the phase separation solvent affected the properties of the cross-linked monolith. The swelling ratio of the cross-linked monolith toward aqueous solutions depended on the buffer pH as well as the monolith fabrication condition. Copper(II) ion was efficiently adsorbed on the cross-linked PGA monolith, and the obtained copper-immobilized monolith showed strong antibacterial activity for Escherichia coli. By combination of the characteristic properties of PGA (e.g., high biocompatibility and biodegradability) and the unique features of monoliths (e.g., through-pore structure, large surface area, and high porosity with small pore size), the PGA monolith possesses large potentials for various industrial applications in the biomedical, environmental, analytical, and separation fields.