• Nuclear Engineering and Technology
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• v.49 no.5
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• pp.1006-1009
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• 2017

We discuss the problems of scattering in this framework, and show that the applied method is very useful in the investigation of the effect of the resonance in the observed scattering cross sections. In this study, not only the scattering cross sections but also the decomposition of the scattering cross sections was computed for the ${\alpha}-{\alpha}$ system. To obtain the decomposition of scattering cross sections into resonance and residual continuum terms, the complex scaled orthogonality condition model and the extended completeness relation are used. Applying the present method to the ${\alpha}-{\alpha}$ and ${\alpha}-n$ systems, we obtained good reproduction of the observed phase shifts and cross sections. The decomposition into resonance and continuum terms makes clear that resonance contributions are dominant but continuum terms and their interference are not negligible. To understand the behavior of observed phase shifts and the shape of the cross sections, both resonance and continuum terms are calculated.

• Preventive Nutrition and Food Science
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• v.9 no.4
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• pp.295-299
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• 2004

Alpha-tocopherol was thermally oxidized and degraded at high temperatures and the resulting products were chromatographically separated and identified by LC-MS. Alpha-tocopherol dissolved in glycerol was heated at 200^{\circ}C for 30 min. The thermal products were separated by hexane extraction and analyzed by HPLC using a reversed phase $\mu$-Bondapak $C_{18}-column$ with two kinds of elution solvents: a mixture of acetonitrile and methanol (3:2), and of acetonitrile, methanol, 2-propanol, chloroform and methylene chloride (3:2:5:0.5:0.5) in a gradient mode. The isolated thermal. products of alpha-tocopherol were more viscous than alpha-tocopherol, and dark brown in color. Major thermal degradation products of alpha-tocopherol were identified by LC-MS, and the structures of thermal products were proposed. Alpha-tocopherol and its thermal degradation products were degraded into fragments, mainly at the non-aromatic parts. The degradation products of alpha-tocopherol. were combined with oxidized product (tocopherylquinone) to make thermal. products through dimerization.

• Korean journal of food and cookery science
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• v.33 no.2
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• pp.181-189
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• 2017

Purpose: This study was conducted to examine the effects of the starch concentration of filled hydrogel and the addition of ${\alpha}-amylase$ and simulated mastication processing in an oral phase on lipid digestion and ${\beta}-carotene$ bioaccessibility of filled hydrogels. Methods: Lipid digestion and ${\beta}-carotene$ bioaccessibility of the filled hydrogels were measured after the samples were passed through an in vitro gastrointestinal tract model consisting of oral, gastric, and small intestinal phases. Results: The initial rate and final extent of lipid digestion were higher in the filled hydrogels than in the emulsion when the filled hydrogels were treated in an oral phase without simulated mastication processing and addition of ${\alpha}-amylase$, regardless of starch concentration. However, when the filled hydrogels were minced using mortar and pestle for 2 min and were exposed to ${\alpha}-amylase$, the filled hydrogel fabricated with 5% starch showed the lowest lipid digestion rate and extent compared to the emulsion and other filled hydrogels. Bioaccessibility of ${\beta}-carotene$ was higher in the filled hydrogels than in the emulsion, regardless of the digestion method performed in an oral phase and starch concentration. However, there were appreciable differences in bioaccessibility of the filled hydrogels depending on whether or not simulated mastication and addition of ${\alpha}-amylase$ were employed. Conclusion: These results suggested that the rheological properties of initial filled hydrogels and simulated mastication processing in an oral phase plays an important role in determining the lipid digestion and ${\beta}-carotene$ bioacccessibility entrapped within filled hydrogels.

• Journal of the Korean Chemical Society
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• v.38 no.7
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• pp.502-508
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• 1994

The measurement of trace amounts of uranium(VI) and thorium(VI) in the solutions containing high concentration of dissolved salts was carried out. The procedure using reversed phase liquid chromatography with trace enrichment techniques has been developed to cope with the high salt content of the samples. 2 ml of sample were passed through a small C_{18}$ reversed phase enrichment column with ${\alpha}$-HIBA eluent (0.11 M, pH 5.5) where the uranium and thorium were separated from other constituents and concentrated. The uranium and thorium were then backflushed from the column onto a deactivated C_{18}$ reversed phase analytical column where furthe separation was achieved with a mixed eluent (pH3.0, 0.17M ${\alpha}$-HIBA/0.0038 M 1-pentanesulfonate). The separated species were determined spectrophotometrically by postcolumn reaction with Arsenazo III, the chromogenic reagent. Detection limits were found within 1 ppb range for both species.

• Journal of Korea Foundry Society
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• v.32 no.2
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• pp.91-97
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• 2012

The effects of Bi and Sb additions on the microstructures and casting properties in lead-free Cu-Zn-Sn broze were investigated. (1) When only Bi was added to the bronze, Bi was precipitated on the ${\delta}$ phase of ${\alpha}$ dendrite cell boundary. When Bi and Sb were added together, Bi was precipitated on the ${\delta}_A$ which was the Sb-rich area in the ${\delta}$ phase. (2) The addition of Sb accelerated the formation of ${\delta}$ phase, and when Sb, Bi and Pb were added, Bi and Pb were precipitated as mixed solution in the ${\delta}_A$ phase. (3) The combined addition of Sb and Bi resulted in the suppression of shrinkage due to the complementary effects of the mass feeding of ${\alpha}$-dendrite cluster covered with ${\delta}$ phase and sealing of micro-shrinkage in the ${\delta}$ phase by solidification expansion of Bi.

• Journal of Magnetics
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• v.5 no.2
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• pp.40-43
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• 2000

Acicular $\alpha-FeOOH\; and\; Ba(OH)_2\cdot8H_2O$ are starting materials in this study. This paper presents the characteristics of the contents of citric acid and heating condition for preparing acicular barium ferrite powder. They control particle shape, crystalline phase, magnetic properties of acicular barium ferrite powder So the effects of the contents of citric acid and heating condition are studied. The experimental condition for starting materials were 800~1000$\circ C$ in firing and 0~40 wt% citric acid, respectively, Ba-ferrite particles fired at the range of 800 $\circ C$to 900 $\circ C$ were maintained as acicular particle shape, but there were mixed particles of acicular and round shape after fired at 950 $\circ C$. Ba-ferrite powder of the single phase was obtained in firing at 900~1000$\circ C$ and with 20 wt.% citric acid. There were unreacted phase of $\alpha-Fe_2O_3 \;and \; BaFe_2O_4$ phases as a second phase in case of sintering at below 850 $\circ C$. Acicular barium ferrite powder of single phase was also produced in firing at 900 $\circ C$ with 20 wt.% citric acid. The saturation magnetization of single phase of acicular $BaFe_12O_19$powder was about 51 emu/g and coercivity was about 4200 Oe.

• Carbon letters
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• v.13 no.3
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• pp.133-138
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• 2012

According to kinetic mechanisms, liquid phase polymerization and solid phase polymerization are different in acrylonitrile (AN) polymerization, and so the relationship between the contribution ratio and molecular weight distribution (MWD) was obtained through theoretic analysis. The precipitation homopolymerization of AN was carried out in a mixture solution of dimethyl sulfoxide (DMSO) and water at $50{\sim}65^{\circ}C$ using ${\alpha}$,${\alpha}^{\prime}$-azobisisobutyronitrile as an initiator. The contribution ratio decreased and approached 0; the MWD also decreased and approached 2 with the increase of the $H_2O$/DMSO ratio from 10/90 to 90/10. The experimental data were found to coincide well with the theoretical equation derived from the mechanisms.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.2
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• pp.68-72
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• 2002

The $\beta$-$FeSi_2$ and $\alpha$-$FeSi_2$ single crystals were synthesized by chemical vapour transport (CVT) using iodine as a transporting agent from the commercially available $FeSi_2$ powder. The $FeSi_2$ powder together with iodine were sealed in an evacuated quartz ampoule and the ampoule then being placed in two-zone electrical furnace for growing crystal. The CVT of $FeSi_2$ with iodine yielded $\beta$-$FeSi_2$ and $\alpha$-FeSi$_2$ single crystals at deposition temperature of 750 and $950^{\circ}C$ respectively. The source temperature was $1050^{\circ}C$ in both cases. The crystals of the $\alpha$-FeSi$_2$ phase were typically plate shaped with dimensions of about $10\times 10 \textrm{mm}^2$, whereas the crystals of orthorhombic $\beta$-$FeSi_2$ phase grew predominantly in the fonts of thin needle of about 10 mm in length. The composition of$\alpha$-FeSicrystal determined by electron probe microanalysis (EPMA) resulted in Si-rich $FeSi_{2.58}$ . 57. Furthermore, the CVT $\beta$-$FeSi_2$ crystal was found to be transformed to the high temperature $\alpha$-$FeSi_2$phase above $930^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1106-1112
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• 2003

For the purpose of making clear the role of oxygen in the thermoelectric properties of FeSi$_2$, thermoelectric measurements and spectroscopic characterization were conducted for the oxidized specimens fabricated from ($\alpha$+$\varepsilon$)-phases and/or $\beta$-phase. Addition of oxygen to FeSi$_2$ prevented both densification during sintering and transformation from metallic phases to semiconducting phase during annealing treatment. In an specimens, electrical conductivity and thermal conductivity decreased with oxidation time. The Seebeck coefficient was positive and small for pure FeSi$_2$. And/or the oxidized specimens fabricated from ($\alpha$+$\varepsilon$)-phases. However, it was negative and showed a maximum peak at about 500 K for the oxidized FeSi$_2$ fabricated from $\beta$-phase. The value of maximum peak increased with oxidation time.

• Applied Biological Chemistry
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• v.50 no.3
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• pp.204-209
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• 2007

The objective of this research was to evaluate the inhibitory activities of phenolic compounds isolated from Crataegi Fructus on ${\alpha}-amylase$ and ${\alpha}-glucosidase$. The content of total phenolic compounds of water extract from Crataegi Fructus was 22.5 mg/g. The inhibitory activity of the water extract (200 ${\mu}g/ml$) from Crataegi Fructus on ${\alpha}-amylase$ and ${\alpha}-glucosidase$ was determined to be 100% and 82.6%, respectively. Isolation of inhibitory compounds was carried out on Sephadex LH-20 and MCI-gel CHP-20 column chromatography using a gradient elution procedure of increasing MeOH in $H_2O$. The chemical structure of the inhibitory compound against ${\alpha}-amylase$ and ${\alpha}-glucosidase$ was confirmed as chlorogenic acid by spectroscopic analysis of FAB-MS, NMR and IR spectrum.