• 한국식품조리과학회지
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• 제11권3호
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• pp.303-308
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• 1995

참죽나무(Cedrela sinensis A.Juss) 잎을 재료로 하여, 김치, 나물, 부각 등의 조리하였을 때 이 식물의 flavonoid 화합물인 quercitrin의 함량 변화를 HPLC에 의한 용매계 THF-dioxane-MeOH-HOAc-5% H/Sub 3/PO/Sub 4/H/Sub 2/O(145:125:50:20:2:658)에서 분석하였다. 참죽김치를 5$^{\circ}C$에서 저장하였을 때의 quercitrin 함량은 1일째 13.06%, 6일째는 10.99%, 10일째는 11.49%, 20일째는 7.21%이며, 김치를 2$0^{\circ}C$에 저장하였을 시는 저장 1일째 15.33%, 6일째 10.83%, 10일째 9.85%, 20일째 5.78% 함유하고 있다. 나물의 경우 주성분인 quercitrin의 함량은 13.06%, 부각은 5.03%이었다. 따라서 김치의 경우 저장 일수가 길어짐에 따라 quercitrin함량은 감소하는 경향을 나타내며, 나물의 경우에는 quercetrin함량의 큰 변화를 볼 수 없고, 부각으로 조리한 경우 quercitrin의 함량은 급격히 감소하였다.

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1573-1578
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• 2009

A computational study of the reactions between Zn-containing species, the products of the thermal decomposition of diethylzinc (DEZn) and water was investigated. The Zn-containing species – $C_2H_5)_2,\;HZnC_2H_5,\;and\;(ZnC_2H_5)_2$ – were assumed to react with water during ZnO metal organic chemical vapor deposition (MOCVD). Density functional theory (DFT) calculations at the level of B3LYP/6-311G(d) were employed for the geometry optimization and thermodynamic property evaluation. As a result dihydroxozinc, $Zn(OH)_2$, was the most probable reaction product common for all three Zn-containing species. A further clustering of $Zn(OH)_2$ was investigated to understand the initial stage of ZnO film deposition. In experiments, the reactions of DEZn and water were examined by in-situ Raman scattering in a specially designed MOCVD reactor. Although direct evidence of $Zn(OH)_2$ was not observed, some relevant reaction intermediates were successfully detected to support the validity of the gas phase reaction pathways proposed in the computational study.

• Nuclear Engineering and Technology
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• 제34권5호
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• pp.517-531
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• 2002

The speciation and solubility of Am, Np, Pu and U have been analyzed by means of the geochemical code MUGREM, under the chemical conditions of domestic deep groundwater, in order to support the preliminary safety assessment for a Korean HLW disposal concept. Under the conditions of groundwaters studied, the stable solid phase is AmOHC $O_3$(s) or Am(OH)$_3$(s), soddyite((U $O_2$)$_2$ $SiO_2$.2$H_2O$) or N $a_2$ $U_2$ $O_{7}$ (c), Np(OH)$_4$(am), and Pu(OH)$_4$(am) for Am, U, Np, and Pu, respectively. The dominating aqueous species are as follows: the complexes of Am(III), Am(OH)$_2$$^{+}$ and Am(C $O_3$)$_2$$^{[-10]}$ , the complexes of U(VI), U $O_2$(OH)$_3$$^{[-10]}$ and U $O_2$(C $O_3$)$_3$$^{4-}$, the complexes of Np(IV), Np(OH)$_4$(aq) and Np(OH)$_3$C $O_3$, and the complexes of Pu(IV), Pu(OH)$_4$(aq) and Pu(OH)$_3$C $O_3$$^{[-10]}$ . The calculated solubilities exist between 1.9E-10 and 1.3E-9 mol/L for Am, between 5.6E-6 and 1.2E-4 mol/L for U, between 3.1E-9 and 1.3E-8 mol/L for Np, and between 6.6E-10 and 2.4E-10 mol/L for Pu, depending on groundwater conditions. The present solubilities of each actinide agree well with the results of other studies obtained under similar conditions.s.

• 자원리싸이클링
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• 제11권1호
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• pp.19-25
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• 2002

$ZnSO_4$- $Na_2$$SO_4$-$H_2$$SO_4$-$NaOH-H_2$O계에 대해 전해질의 농도를 변화시키며 $25^{\circ}C$에서 용액의 pH를 측정하고, K-value방법을 이용하여 이온평형을 해석하였다. 물의 활동도와 용질의 활동도계수는 Pitzer식으로 계산하였다. 평형상태에서 존재하는 용질들의 농도와 활동도계를 전해질의 초기농도로부터 이온평형을 해석하여 구할 수 있었다 이온강도가 4 m정도로 진한 용액에서 pH측정값과 이온평형 해석으로 구한 pH 이론 값은 서로 잘 일치하였다. 액의 이온강도가 3.5에서 4.3사이의 실험조건에서 Pitzer식으로 구한 $ZnSO_4$의 평균이온 활동도계수는 문헌에 발표된 값과 잘 일치하였다.

• Nutrition Research and Practice
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• 제13권4호
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• pp.279-285
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• 2019

BACKGROUND/OBJECTIVES: Excessive production of reactive oxygen species (ROS) such as hydroxyl (${\cdot}OH$), nitric oxide (NO), and hydrogen peroxide ($H_2O_2$) is reported to induce oxidative stress. ROS generated by oxidative stress can potentially damage glial cells in the nervous system. Cordyceps militaris (CM), a kind of natural herb widely found in East Asia. In this study, we investigated the free radical scavenging activity of the CM extract and its neuroprotective effects in $H_2O_2$-induced C6 glial cells. MATERIALS/METHODS: The ethanol extract of CM ($100-1,000{\mu}g/mL$) was used to measure DPPH, ${\cdot}OH$, and NO radical scavenging activities. In addition, hydrogen peroxide ($H_2O_2$)-induced C6 glial cells were treated with CM at $0.5-2.5{\mu}g/mL$ for measurement of cell viability, ROS production, and protein expression resulting from oxidative stress. RESULTS: The CM extract showed high scavenging activities against DPPH, ${\cdot}OH$, and NO radicals at concentration of $1,000{\mu}g/mL$. Treatment of CM with $H_2O_2$-induced oxidative stress in C6 glial cells significantly increased cell viability, and decreased ROS production. Cyclooxygenase-2 and inducible nitric oxide synthase protein expression was down-regulated in CM-treated groups. In addition, the protein expression level of phospho-p38 mitogen-activated protein kinase (p-p38 MAPK), phospho-c-Jun N-terminal kinase (p-JNK), and phospho-extracellular regulated protein kinases (p-ERK) in $H_2O_2$-induced C6 glial cells was down-regulated upon CM administration. CONCLUSION: CM exhibited radical scavenging activity and protective effect against $H_2O_2$ as indicated by the increased cell viability, decreased ROS production, down-regulation of inflammation-related proteins as well as p-p38, p-JNK, and p-ERK protein levels. Therefore, we suggest that CM could play the protective role from oxidative stress in glial cells.

• 대한화학회지
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• 제32권3호
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• pp.179-185
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• 1988

과염소산이 존재하는 디메틸포름아미드 수용액에서 벤질알코올과 VO_2\;^+$를 반응시키면 $VO^{2+}$와 벤즈알데히드를 생성한다. 이때 생성물인 $VO^{2+}$와 벤즈알데히드는 적외선 분광광도법과 기체크로마토그래피법으로 확인하였다. 벤질알코올에 의한 VO_2\;^+$의 환원반응에 대한 속도론적 연구는 분광광도법으로 행하였다. 이 반응에 대한 실험속도식은 다음과 같이 나타낼 수 있으며 속도결정단계는 $VO^{2+}$와 $C_6H_5CHOH$의 생성과정이다. $-d[VO_2\;^+]/dt=2\{\\{k_O+k_H[HClO_4]\}\[VO_2\;^+][C_6H_5CH_2OH]$이 반응의 활성화파라미터는 ${\Delta}H^{\neq}=13.32{\pm}1.73\;kcalmol^{-1}$ 이고 ${\Delta}S^{\neq}$ 는 $-31.02{\pm}0.09\;calmol^{-1}K^{-1}$이다.

• Transactions on Electrical and Electronic Materials
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• 제5권5호
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• pp.189-193
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• 2004

Pure and Sn or Pt doped $\alpha-Fe_2O_3$ thin films were prepared on $Al_2O_3$ substrates by RF-magnetron sputtering method and the sensitivities were compared. It was found that pure $\alpha-Fe_2O_3$ thin films did not exhibit much selectivity in CO and $i-C_4H_{10}$ gases while it showed the high sensitivity in proportion to the gas concentration of $C_2H_{5}OH$ gas. Pt-doped $\alpha-Fe_2O_3$ showed to be alike sensing properties as pure $\alpha-Fe_2O_3$ thin film in $C_2H_{5}OH$ gas. However, Sn-doped $\alpha-Fe_2O_3$ thin films exhibited the excellent sensitivity and selectivity in Hz gas. After microstructure modification by plasma etching on pure $\alpha-Fe_2O_3$ thin films, the gas sensing characteristics were dramatically changed.

• Bulletin of the Korean Chemical Society
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• 제17권2호
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• pp.128-131
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• 1996

From Raman spectra, the ${\nu}g$C=O frequencies of 4-substituted benzaldehydes were found to correlate with the ${\sigma}_p$ values of the 4-x atom or group as well as the acceptor number (AN) values of solvents. In various solvents, the ${\nu}g$C=O frequency of benzaldehyde decreased upon the increase of benzaldehyde concentration. This shift was mainly due to the hydrogen bonding between the carbonyl oxygen and/or aldehydic proton of benzaldehyde and the solvent molecules. Over the 1-80 volume % change, the ${\nu}g$C=O frequency of benzaldehyde down shifted from 1709.4 $cm^{-1}$ to 1700.2 $cm^{-1}$ in CCl4 solution and from 1703.0 $cm^{-1}$ to 1698.0 $cm^{-1}$ in $C_2H_5OH$ solution. This is due to the fact that hydrogen bonding between the benzaldehyde and C2H5OH was much stronger than that between the benzaldehyde and the other solvents.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.131-131
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• 2003

The advent of photonic technologies in the field of communications and data transmission has been heavily increasing the demand in integrated optical (IO) circuits capable of accomplishing not only simple tasks like signal, but also more sophisticated functions like all-optical signal routing or active multiplexing/demultiplexing. In the last decade, sol-gel technology has been widely used to prepare optical materials. Sol-gel processes show many promises for the development of low-loss, high-performance glass integrated optical circuits. However, crack formation is likely to occur during heat treatment in thick gel films. In order to overcome the critical thickness limitation, the organic-modified silicate has been widely used. In this case coating matrices have been prepared from the organo-silanes of T structures, acidic catalyst and the as-prepared gel films have been heat-treated below 200$^{\circ}C$ to avoid the crack formation and the degradation of organic components. However, the films prepared in the acidic condition and the low heat temperature make the films contain high OH groups which is the major optical loss function. In this work, C$\sub$6/H$\sub$5/SiO$\sub$1.5/ films were prepared on silicon substrate by sol-gel method using base catalyst in a PTMS/NH$_4$OH/H$_2$O/C$_2$H$\sub$5/OH system. The sol showed spinable viscosity at 50 wt% of solid content, and neglectable viscosity change with time. The films were crack-free and transparent after curing at 450 $^{\circ}C$, and highly condensed to minimize OH content in C$\sub$6/H$\sub$5/SiO$\sub$1.5/ networks. The effects of heat treatment of the films are characterized on the critical thickness, the chemical composition and the refractive indices by means of SEM, FT-IR, TGA, prism coupler, respectively.

• 공업화학
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• 제30권1호
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• pp.34-38
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• 2019

탄산화 공정을 위한 Ca 추출원으로 시멘트 산업부산물을 사용하였다. ICP와 XRD 분석을 통하여 시멘트 산업부산물은 대부분 CaO와 KCl로 구성되어 있음을 확인하였다. 최적화된 추출용제의 종류 및 농도는 1.5 M of hydrochloric acid이며 최적의 고액비는 0.1 g/mL이었다. 추출 성능 실험 결과를 통해 양이온의 추출효율은 이온 결합 형태 및 용해도에 의존함으로 판단되었다. 또한 추출 공정 후, 첨가물의 종류 및 주입 순서에 따라 선택적으로 양이온이 분리될 수 있음을 확인하였다. pH를 9.5, 13으로 조절하기 위하여 NaOH를 주입하였을 때 불순물과 $Ca(OH)_2$가 침전되었으며, $C_2H_5OH$를 주입한 경우 KCl 형태로 분리된 K가 침전되었다.