• Title/Summary/Keyword: MgB2

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The Fabrication of Low Temperature Firing Substrate of $Li_2O-MgO-MgF_2-SiO_2-B_2O_3$ system

  • Park, Jung-Houn;Park, Dae-Hyun;Kang, Won-Ho
    • Journal of the Microelectronics and Packaging Society
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    • v.6 no.4
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    • pp.35-39
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    • 1999
  • The $Li_2O-MgO-MgF_2-SiO_2$glasses with addition of $B_2O_3$ were investigated in order to make glass-ceramics for low temperature firing substrate. Glasses were made by melting at $1450^{\circ}C$ in the electronic furnace and crystallized at $750^{\circ}C$. The crystal phases were polycrystalline of lithium boron fluorphlogopite and lithium fluorhectorite. The crystal shape was chanced to granule type from needle type with increasing $B_2O_3$ content. Average particle size of the glass-ceramics after water swelling was 3.77$\mu\textrm{m}$. The optimum sintering temperature and sintering shrinkage of the substrate were $900^{\circ}C$ and 13.4%, respectively.

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Influence of Mechanical Activation on Synthesis of Compounds in B/C-Mg/Al/Ca System

  • Urakaev, F.Kh
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2004.05a
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    • pp.60-65
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    • 2004
  • The possibility of mechano-chemical synthesis and influence of mechanical activation on thermal synthesis of borides and boron carbides of mass-low metals is investigated. The opportunity of mechanochemical synthesis in the mill AGO-2 of such compounds as Al $B_2$and Ca $C_2$ $B_2$is established. Influence of mechanical activation in the mill SPEX 8000 on synthesis of such compound as $Mg_{0.5}$A $l_{0.5}$ $B_2$is shown. Features of synthesis in systems containing metal magnesium are considered.d.d.

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Contents of Antioxidative Components from Pulpy and Seed in Wild Haw (Crataegus pinnatifida BUNGE) (자생 산사(Crataegus pinnatifida BUNGE)과육 및 씨의 항산화성분 함량)

  • Kim, Han-Soo;Duan, Yishan;Kim, Min-A;Jang, Seong-Ho
    • Journal of Environmental Science International
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    • v.23 no.11
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    • pp.1791-1799
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    • 2014
  • This study was conducted to evaluate the contents of antioxidative components from pulpy and seed in wild haw (Crataegus pinnatifida $B_{UNGE}$). Pulpy and seed of haw were smashed, then measured for color properties, antioxidative components of ascorbic acid, phytic acid, proanthocyanidin, anthocyanin, total carotene, ${\beta}$-carotene, lycopene, chlorophyll a, b and tannin. The $a^*$, $b^*$ and $C^*$ values of seed were significantly lower than pulpy, but $L^*$ and $H^{\circ}$ values were higher than that of pulpy. Ascorbic acid contents of pulpy and seed were found to be $10.89{\pm}1.69mg/100g$ and $1.45{\pm}0.16mg/100g$, respectively. Phytic acid, proanthocyanidin, total carotene and tannin contents of pulpy and seed were $689.17{\pm}3.63mg/g$, $597.78{\pm}2.93mg/g$; $355.61{\pm}19.39mg/g$, $49.12{\pm}4.97mg/g$; $8.32{\pm}0.42mg%$, $0.80{\pm}0.01mg%$; $7.53{\pm}0.09mg/g$, $1.02{\pm}0.03mg/g$, respectively. Similarly, ${\beta}$-carotene, lycopene, chlorophyll a and chlorophyll b contents of pulpy also displayed higher values than that of seed. On the contrary, anthocyanin content of seed ($4.24{\pm}0.33mg/L$) was remarkably higher than pulpy ($0.99{\pm}0.62mg/L$). The results showed that pulpy could be severed as great natural antioxidant and biohealth functional food.

Quality comparison of non-thermal sterilized raw apple vinegar and commercial apple vinegar products

  • Sun Hwa Kim;Ji-Hyung Seo;Yong-Jin Jeong
    • Food Science and Preservation
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    • v.31 no.2
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    • pp.235-244
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    • 2024
  • A nonthermally sterilized raw apple vinegar was manufactured using an ultra-fine filtration process (0.2 ㎛ membrane filter) and its quality was comparable to commercially available vinegar products. First, using apple concentrate as a raw material, it was possible to produce non-thermal sterilized Using a two-stage fermentation process of alcohol and acetic acid fermentations, a non-thermally sterilized raw apple vinegar with pH 2.94 and an acidity of 6.20% was produced from an apple concentrate. The fermentation process increased the browning index significantly. However, the fundamental quality parameters of the non-thermal sterilized raw apple vinegar (A) with sterilized apple vinegar (B) did not differ significantly. The pH (2.92-2.95) of apple vinegar (A and B) was higher than that (pH 2.65-2.70) of commercial vinegar (C and D), and the total acidity, which is in the range of 6.20-6.21% and 6.53-6.90%, respectively, was higher in samples C and D than in samples A and B. However, four kinds of organic acids were detected in non-thermal sterilized raw apple vinegar (A), and its total organic acid content (6,245.00 mg%) was significantly higher than that of other samples (B, C, D) (p<0.05). In particular, malic acid content, as a main organic acid in apples, was very high in sample (A) (244.83 mg%) and sample (B) (210.21 mg%), compared to commercial products C (125.78 mg%) and D (86.90 mg%). The total polyphenol content and antioxidant activity of fermented apple vinegar (A, B) were more than twice as high as those of commercial products (C, D). Vinegar A had higher total polyphenol content than vinegar B. The above results suggest it is possible to manufacture and commercialize non-thermal sterilized raw apple vinegar with higher organic acid content and antioxidant properties using ultra-fine filtration.

Characteristics of Biological Phosphorus Removal in the MBR (MBR 공정에서의 인 제거 특성)

  • Choi, Hee-Jeong;Lee, Seung-Mok
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.2
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    • pp.197-204
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    • 2007
  • The reciprocal effects towards the enhanced biological phosphorus removal were performed for anaerobic, aerobic and anoxic phases. The batch experiments showed that the p-absorption in the anoxic phase was 50% lower than aerobic phase. The correlation coefficient between p-back-solution and p-absorption was found to be $R^2=0.557$ however, the coefficient b(b = 8.4049) was relatively higher than the other researchers results. The increase and/or acceptance of the $K^+-,\;Mg^{2+}-$ and $NH_4-N$-concentration was proportional to those of the $PO_4-P$-concentration in the batch test. The relationship between $K^+-,\;Mg^{2+}$ and $PO_4-P$ was determined. The average value of this relation-ship agreed with 0.2 mol $K^+Ion$ / mol $PO_4-P$ ion and 0.21 mol $Mg^{2+}Ion$ / moi $PO_4-P$ ion in the anaerobic phase. The absorbed ratio of $K^+$ to $Mg^{2+}$ over $PO_4-P$ was found to be 1 : 5.

Investigation on the phonon behavior of MgB2 films via polarized Raman spectra

  • R. P. Putra;J. Y. Oh;G. H. An;H. S. Lee;B. Kang
    • Progress in Superconductivity and Cryogenics
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    • v.26 no.1
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    • pp.14-19
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    • 2024
  • In this study, we explore the anisotropy of electron-phonon coupling (EPC) constant in epitaxially grown MgB2 films on c-axis oriented Al2O3, examining its correlation with the critical temperature (Tc) and local structural disorder assessed through polarized Raman scattering. Analysis of the polarized Raman spectra reveals angle-dependent variations in the intensity of the phonon spectra. The Raman active mode originating from the boron plane, along with two additional phonon modes from the phonon density of states (PDOS) induced by lattice distortion, was distinctly observed. Persistent impurity scattering, likely attributed to oxygen diffusion, was noted at consistent frequencies across all measurement angles. The EPC values derived from the primary Raman active phonon do not significantly vary with changing observation angles, followed by that the Tc values calculated using the Allen and Dynes formula remain relatively constant across all polarization angles. Although the E2g phonon mode plays a crucial role in the EPC mechanism, the determination of Tc values in MgB2 involves not only electron-E2g coupling but also contributions from other phonon modes.

Characteristics of Mung Bean Powders After Various Hydrolysis Protocols (녹두분말의 가수분해 조건에 따른 특성 비교)

  • Kim, Ok-Mi;Gu, Young-Ah;Jeong, Yong-Jin
    • Food Science and Preservation
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    • v.14 no.3
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    • pp.301-307
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    • 2007
  • To efficiently use Korean mung beans, the functional characteristics of mung bean powder(A), unhydrolyzed mung bean flour(B), and mung bean flour hydrolyzed under optimum conditions(C), were compared. The contents of protein, fat, carbohydrate, ash, and water, did not vary greatly with different treatment methods. The color values of (B) and (C) were similar, while the L value of (A) was higher than those of the other samples. Thereducing sugar content of (C) was highest at 292.63 mg%, while the total phenol contents of (A) and (C) were similar at 38.63 mg% and 38.38 mg%, respectively. The molecular weight of (A) was under 17 kDa by SDS-PAGE, and was lower than the molecular weights of the other samples (B, C), which generally ranged from 17 kDa to 72 kDa. The free sugar content of (C) was highest at 1,125.16 mg%, while (A) and (B) yielded values of 86.36 mg% and 54.20 mg%, respectively. Total free amino acid contents were in the order(C)(B)(A), and were 22,116.35 mg%, 2,731.29 mg%, and 578.54 mg%, respectively. The amino acid content of (C) was 8,231.42 mg% and was higher than those of (A) or(B). The DPPH free radical scavenging abilities of (A) and (C) were high, at 62.1% and 57.63%, respectively, while (B) showed a lower value at 19.26%. Fibrinolytic activity was highest(24.01%) in (C), and was 20.69% in (A) and 18.06% in (B). The above results indicate that mung bean flour hydrolyzed under optimal conditions (C) had the highest functional and quality characteristics, in comparisonh with unhydrolyzed flour (B) and mung bean powder (A). Diverse applications of hydrolyzed mung bean flour are anticipated.