• 약학회지
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• 제29권2호
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• pp.62-69
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• 1985

The isomeric intermediates, $3{\alpha}$and $3{\beta}-amino-5{\alpha}-cholestane required for the synthesis of N-nitrosoureas, N-(2-chloroethyl)-N-nitrosocarbamoyl-$3{\alpha}-amino-5{\alpha}$-cholestane (9), N-methyl-N-nitrosocarbamoyl-3${\alpha}-amino-5{\alpha}-cholestane$ (10), N-(2-chloroethyl)-N-nitrosocarbamoyl-$3{\beta}-amino-5{\alpha}-cholestane$: (7), and N-methyl-N-nitrosocarbamoyl-$3{\beta}-amino-5{\alpha}-cholestane$ (8) were obtained through the $LiAlH_{4}$ reduction of $5{\alpha}$-cholestan-3-one oxime, followed by the chromatographic separation: the assignment of the stereochemistry of both isomers were based on the shape and chemical shift of $C_{3}$-proton resonances on their NMR spectra and on the elution mobility on the TLC. The urea intermediates, N-(2-chloroethyl) carbamoyl-3.alpha.-amino-5.alpha.-cholestane (13), N-methylcarbamoyl-$3{\alpha}-amino-5{\alpha}-cholestane$ (14), N-(2-chloroethyl) carbamoyl-$3{\beta}-amino-5{\alpha}-cholestane (11) and N-methyl-$3{\beta}-amino-5{\alpha}$-cholestane (12) were prepared by the treatment of each isomers ($3{\alpha}$-amino-and $3{\beta}-amino-5{\alpha}$-cholestane) with alkyl isocyanates in anhydrous $CHCl_{3}$, and the corresponding nitrosoureas, 7-10 were obtained by the nitrosation of the ureas, 11-14, with AcOH (or HCOOH)/$NaNO_{2}$ in ice-cold condition. The inhibitory activity of the nitrosoureas, 7-10, and their intermediates, 12-14 towards the growth of L1210 murine leukemia cells, were examined. Among them, the compounds 9 and 10 exhibited high activity having $ED_{50}$ to be 5.5g/ml and 6.1g/ml, respectively.

• 한국세라믹학회지
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• 제22권6호
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• pp.21-28
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• 1985

The properties of magnetic recording materials largely depend on their shape magnetic anisotropy. The control of their shape and size distribution is very important for improving magnetic properties. The silica-coated goethite$(SiO_2$/$\alpha$-FeOOH=1.5wt%) having acicular shape was prepared. The sillica-coated goethite was heat-treated at 40$0^{\circ}C$~1,00$0^{\circ}C$ 1hr and then reduced at 50$0^{\circ}C$ 2hr. When the silica-coated goethite was heat-treated at 80$0^{\circ}C$ its acicular shape was maintained and its magnetic properties were improved(Hc: 1,325 Oe $\sigma$m:138.8 emu/g, Rs:0.56) However the acicular shape of the paricles was broken for non-coated hematite obtained by dehydration at 80$0^{\circ}C$ They were sintered and showed poor magnetic properties.

• 한국세라믹학회지
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• 제34권11호
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• pp.1159-1164
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• 1997

Magnetite(Fe3O4) powders were synthesized through glycothermal reaction by using crystalline $\alpha$-FeOOH as precursor and ethyleanne glycol as solvent. The phase, morphology and particle size of synthesized powders were characterized by XRD and an SEM. When only ethylene glycol was used as solvent, the phase was transformed from $\alpha$-FeOOH to $\alpha$-Fe2O3 and finally Fe3O4 at 27$0^{\circ}C$ for 6hr without morphological change. But by addition of water, Fe3O4 powders were synthesized at 23$0^{\circ}C$ for 3hr through solution-recrystalization process. As the content of water addition increased, the particle shape changed from sphere to octahedron and the partcle size increased. When the excess amount of water added, residual $\alpha$-FeOOH or $\alpha$-Fe2O3 was recrystalized.

• 한국세라믹학회지
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• 제35권3호
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• pp.239-244
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• 1998

출발원료인 ferric nitrate와 ethylene glycol를 사용하여 iron complex를 제조하였으며 이를 $350^{\circ}C$ 이상의 온도에서 열처리하여 200nm 이하의 미세한 입자 크기를 갖는 ${\alpha}-Fe_2O_3$ 분말을 얻었다. 또한 열분석 X-선 회절 분석 및 적외선 분광 분석을 통하여 제조된 iron complex의 분해 mechanism에 대하여 조사하였고, 출발원료의 조성비 및 반응온도에 따른 입자 크기 및 형상의 변화 양상을 전자현미경 분석과 비표면적 분석을 통하여 조사하였다.

• Archives of Pharmacal Research
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• 제28권11호
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• pp.1257-1262
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• 2005

MMP-9 is a metalloproteinase capable of basement membrane degradation in vivo. Expression of MMP-9 can be found in normal conditions such as trophoblasts, osteoclasts, and leukocytes and their precursors. They also occur as well as in pathological conditions, such as the invasive growth of primary tumors, metastasis, angiogenesis, rheumatoid arthritis, and periodontal diseases. MMP-9 upregulation can be highly induced by a wide range of agents. These agents include growth factors, cytokines, cell-cell, and cell-ECM adhesion molecules, and agents altering cell shape. Here, we observed that TNF-$\alpha$ stimulated human monocytic cell line, HL-60 produced MMP-9 in a dose and time dependent manner. Real time PCR results indicated transcriptional upregulation of MMP-9 as early as 3 h post TNF-$\alpha$ stimulation. To investigate the signaling pathway underlined in TNF-$\alpha$ induced MMP-9 expression, three MAP kinase inhibitors were added to cells 1 h prior to TNF-$\alpha$ treatment. The ERK inhibitor completely abolished MMP-9 expression by TNF-$\alpha$. But neither p38 MAP kinase nor JNK inhibitor had an effect on TNF-$\alpha$ induced MMP-9 expression, suggesting that ERK activation is required for the MMP-9 induction by TNF-$\alpha$. Taken together, we found that TNF-$\alpha$ stimulation facilitates ERK activation, which results in the transcriptional upregulation of MMP-9 gene and subsequent MMP-9 production and secretion.

• Bulletin of the Korean Chemical Society
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• 제15권11호
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• pp.957-961
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• 1994

Epoxidation of olefins catalyzed by iron-tetraarylporphyrins were studied to see the shape selectivity in the competing reaction between cis-and trans- or internal and external olefins. Cis-olefins were more reactive than trans-olefins in the competing reaction between cis-and trans-olefins. Interestingly, in the epoxidation of $cis-{\beta}-methystyrene$ by ${\alpha}{\beta}{\alpha}{\beta}$ atropisomer of Fe(III)TNPPPCl and iodosylbenzene, 27% of total product was phenylacetone. The unusually large amount of phenylacetone may be produced by hydride rearrangement of carbocationic intermediate. Regioselectivity of the reaction was also studied by using the most sterically hindered Fe(III)TTPPPCl. In the epoxidation of limonene with Fe(III)TTPPPCl, the disubstituted double bond was more reactive than trisubstituted double bond. This is in contrast to the results obtained with other iron-tetraarylporphyrins. Similar trend was also observed in the competing reaction between mono-and di-substituted olefins.

• 천문학회보
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• 제37권2호
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• pp.113.1-113.1
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• 2012

The characteristics of Doppler shifts in a quiet region of the Sun are investigated by comparing between the $H{\alpha}$ line and the Caii infrared line at 854.2 nm. A small area of $16^{\prime\prime}{\times}40^{\prime\prime}$ was observed for about half an hour with the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope (NST) at Big Bear Solar Observatory. The observed area contains a network region and an internetwork region, and identified in the network region are $H{\alpha}$ fibrils, Caii fibrils and bright points. We infer the Doppler velocity from each line profile at a point with the lambdameter method as a function of half wavelength separation ${\Delta}{\lambda}$. It is confirmed that the bisector of the spatially-averaged Caii line profile has an inverse C-shape of with a significant peak redshift of +1.8 km/s. In contrast, the bisector of the spatially-averaged $H{\alpha}$ line profile has a different shape; it is almost vertically straight or, if not, has a C-shape with a small peak blueshift of -0.5 km/s. In both the lines, the bisectors of bright network points are much different from those of other features in that they are significantly redshifted not only at the line centers, but also at the wings. We also find that the spatio-temporal fluctuation of Doppler shift inferred from the Caii line is correlated with those of the $H{\alpha}$ line. The strongest correlation occurs in the internework region, and when the inner wings rather than the line centers are used to determine Doppler shift. In this region, the RMS value of Doppler shift fluctuation is the largest at the line center, and monotonically decreases with ${\Delta}{\lambda}$. We discuss the physical implications of our results on the formation of the $H{\alpha}$ line and Caii 854.2 nm line in the quiet region chromosphere.

• 폴리머
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• 제36권2호
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• pp.229-234
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• 2012

이 논문은 판상형 충전제의 함량과 배향에 따라 폴리프로필렌 복합체의 영률 변화에 미치는 영향을 연구하였다. 이론적인 예측은 Lee와 그의 연구자들에 의해 제안된 두 개의 종횡비, ${\rho}_{\alpha}=a_1/a_3$과 ${\rho}_{\beta}=a_1/a_2$를 이용하여 3차원 타원체의 형상을 계산하였고 실험값과 비교 분석하였다. 판상형 충전제로 운모와 탈크를 사용하였다. 충전제의 형태는 SEM을 이용해 관찰하였고, 종횡비는 고분자의 흐름을 기준으로 좌표축을 설정하여 통계적 방법으로 계산하였다. 충전제가 운모인 경우에 ${\rho}_{\alpha}=13.5$와 ${\rho}_{\beta}=1.8$이었고, 탈크의 경우는 ${\rho}_{\alpha}=3.8$과 ${\rho}_{\beta}=1.4$이었다. 또한 충전제의 2개의 종횡비와 함량이 기계적 물성에 미치는 영향을 실험적으로 연구하였다. 운모의 경우 30 wt% 함량일 때 $E_{11}$이 약 2.7배 향상되었다. 탈크의 경우는 $E_{11}$이 약 2.3배 향상하였다.

• Journal of Magnetics
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• 제5권2호
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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.

• Nuclear Engineering and Technology
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• 제41권1호
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• pp.113-124
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• 2009

The line shape functions for the Doppler-broadened gamma ray spectrum are considered in the $^{10}B(n,{\alpha}{\gamma})^7Li$ reaction occurring in a surrounding medium where the excited $^7Li$ nucleus is slowed down and stopped before decay. The phenomenological form of the stopping power was used for the broadening effect. Convolution with the detailed response of a germanium detector is taken into consideration for the simplest case of solely electronic stopping. A numerical study for the analysis of $^{10}B$ by thermal neutron capture is conducted by performing a parametric search and fitting the measured spectrum in a least-squares approach. In comparison with the previous numerical approach using the same analysis, the computational speed is increased and reliable information concerning the stopping power of the medium is obtained while estimating the uncertainty. Implementation of the routine analysis of $^{10}B$ is facilitated on a recent version of the gamma ray spectrum analysis package HyperGam.