• Journal of Ginseng Research
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• 제25권2호
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• pp.68-73
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• 2001

Studies were performed to determine the effect of red ginseng and white ginseng on jejunal crypt survival, endogenous spleen colony formation, and apoptosis of jejunal crypt cells in irradiated mice. The radioprotective effect of ginseng was compared with the effect of diethyldithocarbamate(D). Jejunal crypts were protected from irradiation by pretreatment of red ginseng (50 mg/kg B.W., I.P. at 36 and 12 hours before irradiation) and white ginseng (50 mg/kg B.W., I.P. at 36 and 12 hours before irradiation). Red ginseng administration before irradiation and both pretreatment and posttreatment (50 mg/kg B.W., I.P. at 30 minutes after irradiation) of white ginseng resulted in an increase of the formation of endogenous spleen colony. the frequency of radiation-induced apoptosis in intestinal crypt cells was also reduced by both pretreatment and posttreatment of red ginseng, and pretreatment of white ginseng. The radioprotective effect of DDC (1000 mg/kg B.W., I.P. at 30 minutes before irradiation) on jejunal crypt survival and apoptosis was similar to those of ginseng treatment. Treatment with DDC showed no significant modifying effects on formation of endogenous spleen colony. These results indicated that ginseng might be a useful radioprotector. Further studies are needed to characterize effective radioprotective components and mechanism of ginseng.

• 한국세라믹학회지
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• 제23권1호
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• pp.51-59
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• 1986

It was the first time the MgO-C brick was developed for the lining materials in the hot spots in electric are furnace in 1972. MgO-C brick is high registant to thermal and structural spalling. Futhermore for the reason that carbon is hard to react with slag and MgO is high fireproof MgO-C brick shows a high corrosion registance to slag attack compared with conventional basic refractories. Owing to their excellent properties the use of MgO-C refractories are being developed widely in the field of shaped refractories and even in that of monolithic refractories. In this paper the oxidation of carbon the infiltration of slag into the brick texture and effects of additions were investigated. The results obtained were as follows : 1) The use of fused MgO-clinker and high purity carbon as raw materials increased the corosion registance and hot modulus of rupture of MgO-C brick. 2) As the oxidation reaction of the carbon proceeded the slag infiltrated into the brick texture. And then the slag components reacted with the MgO grains and formed low melting point compounds particulary CaO.MgO.$SiO_2$ and 3CaO.MgO.$2SiO_2$ that resulted in the wear of the brick. 3) It is recongnized the Al, Si, $B_3C$ effects on the oxidation registant properties of MgO-C brick by contribu-ting to the decrease of permeability according to the formation of $Al_4C_3$, SiC, $B_2O_3$ and the decrease of open pores relating to the formation of MgO.Al2O3, $SiO_2$, 3MgO.$B_2O_3$ at the decarbonized layer.

• 한국초전도ㆍ저온공학회논문지
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• 제16권1호
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• pp.9-13
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• 2014

Effects of neutron irradiation on the superconducting properties of the undoped $MgB_2$ and the carbon(C)-doped $MgB_2$ bulk superconductors, prepared by an in situ reaction process using Mg and B powder, were investigated. The prepared $MgB_2$ samples were neutron-irradiated at the neutron fluence of $10^{16}-10^{18}n/cm^2$ in a Hanaro nuclear reactor of KAERI involving both fast and thermal neutron. The magnetic moment-temperature (M-T) and magnetization-magnetic field (M-H) curves before/after irradiation were obtained using magnetic property measurement system (MPMS). The superconducting critical temperature ($T_c$) and transition width were estimated from the M-T curves and critical current density ($J_c$) was estimated from the M-H curves using a Bean's critical model. The $T_cs$ of the undoped $MgB_2$ and C-doped $MgB_2$ before irradiation were 36.9-37.0 K and 36.6-36.8 K, respectively. The $T_cs$ decreased to 33.2 K and 31.6 K, respectively after irradiation at neutron fluence of $7.16{\times}10^{17}n/cm^2$, and decreased to 22.6 K and 24.0 K, respectively, at $3.13{\times}10^{18}n/cm^2$. The $J_c$ cross-over was observed at the high magnetic field of 5.2 T for the undoped $MgB_2$ irradiated at $7.16{\times}10^{17}n/cm^2$. The $T_c$ and $J_c$ variation after the neutron irradiation at various neutron fluences were explained in terms of the defect formation in the superconducting matrix by neutron irradiation.

• 한국작물학회지
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• 제32권4호
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• pp.466-470
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• 1987

Hordeora spontaneum의 7계통의 trisomic 식물체에서 미숙배를 채취하여 2.4-D 1mg/$\ell$와 2mg/$\ell$가 첨가된 B5배지와 CI 배지에 치상하여 callus 형성을 유도했다. Callus 유기는 2.4-D 1mg/$\ell$ 첨가구에서는 B5배지보다 CI배지에서 양호하였으나, 2mg/$\ell$첨가구에서는 B5배지와 CI배지간에 차이가 없었다. 또 trisomic type에 따른 callus유기율에서도 차이는 인정되지 않았으며, 평균 Callus 유기율은 83 %였다. 식물체재생에서는 kinetin 1mg/$\ell$첨가구가 무첨가구보다 양호하고, 무첨가구에서는 B5배지보다 SI 배지가 좋은 경향을 나타냈으나 다같이 유의차는 없었다. 합계 46개체가 재생되었으며 그후 17개체가 엽녹소 결핍개체였고 재생율은 7.6%였다.

• Journal of Plant Biotechnology
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• 제34권3호
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• pp.223-227
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• 2007

제주상사화의 잎 및 뿌리 조직으로부터 형성된 캘러스 및 구형 소자구로부터 효율적인 기내 식물체 재생체계를 확립하였다. 2,4-D가 첨가된 B5 배양배지에서 12주 배양 후 제주상사화의 잎 조직으로부터 백색의 구형 세포괴 및 캘러스가 동시에 발달하였으며 그 빈도는 32.1%이었다. 그러나 3 mg/L 이상의 고농도 2,4-D 처리구에서는 캘러스 형성빈도가 14%로 크게 감소하였으며 10 mg/L 2,4-D 처리구에서는 캘러스 형성이 전혀 이루어지지 않았다. 잎 조직과 달리 뿌리 절편의 경우 3 mg/L 2,4-D 처리구에서 캘러스 형성빈도가 36.1%로 가장 높았으며 BA 단독처리구나 2,4-D와 BA의 혼용처리구에서는 그 빈도가 감소하였다. 형성된 백색의 구형세포괴는 생장조절제가 첨가되지 않은 B5배지에 배양하면 소자구 발달 경로를 거쳐 소식물체로 발달이 이루어졌다. 소식물체는 생장조절제가 첨가되지 않은 1/2MS 기본배지로 옮겨 명배양한 결과, 약 배양 2주후부터 녹색의 잎이 신장되는 것을 관찰 하였으며 4주 후 뿌리 발달이 이루어지면서 정상적인 식물체로 발달하였다. 재생된 소식물체는 배양기내에서 순화과정을 통해 토양이식이 가능하였다. 본 연구에서 확립된 제주상사화의 식물체 재생체계는 제주상사화의 대량증식 수단은 물론, 유용 형질 도입을 통한 분자육종의 수단 및 유용 유전자원의 장기보전을 위한 초저온 보존 연구의 직접적인 연구소재로 활용이 가능할 것으로 예상된다.

• 한국약용작물학회지
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• 제5권1호
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• pp.21-27
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• 1997

반하의 조직배양을 통한 대량증식방법 확립의 일환으로 실시한 기내배양에서의 소괴경형성 및 식물체 분화에 영향을 미치는 배지 NAA와 Thidiazuron의 최적조건을 구명하고져 실시한 실험의 결과는 다음과 같다. 1, 식물생장조절물질로 NAA와 TDZ을 단독처리 할 때 TDZ $0.5\;{\mu}M$에서 shoot수가 45개로 가장 양호하였으며 root분화는 NAA 2.0 mg/l 에서 가장 양호하였다. 2. NAA 0.1 mg/l +TDZ $2.0\;{\mu}M$ 조합처리에서 shoot분화가 가장 양호하였으며 NAA 2.0 mg/l +TDZ $2.0\;{\mu}M$ 처리시에 가장 저조하였다. 3. 반하의 소괴경 형성은 MS배지에서는 TDZ $5.0\;{\mu}M$ 단독처리와 NAA 0.1 mg/l +TDZ $2.0\;{\mu}M$ 처리에서 소괴경 형성이 가장 양호하였다. B5배지에서는 TDZ $1.0\;{\mu}M$ 단독처리와 NAA 1.0 mg/l +TDZ $5.0\;{\mu}M$ 처리에서 소괴경 형성이 가장 양호하였으나 생체중은 NAA 0.1 mg/l 와 TDZ $5.0\;{\mu}M$의 단독처리에서 생체중이 가장 무거웠다. 4. MS, MG, B5배지조성에 따른 소괴경형성은 MG배지에서 30일배양후 가장 양호하였으며 생체중도 좋았다. 5. 분화된 식물체 뿌리분화에는 IAA보다 NAA가, MS 보다 1/2MS가 더 효과적인 결과를 보여 1/2MS배지에 NAA 2 mg/l 를 처리하였을 때 23.3개의 뿌리가 유도되어 가장 높은 결과를 보였다. 완전분화된 식물체를 vermiculite가 담긴 포트에 이식하여 온실에서 순화시킨 결과 80%정도의 생존율을 보였다.

• 식물조직배양학회지
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• 제27권3호
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• pp.197-202
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• 2000

조직배양을 이용한 처녀치마 대량증식을 위한 적정배지, 생장조절제 및 농도구명을 위해 본 연구를 수행하였다. Shootb 및 roots분화의 경우 zeatin 3.0 mgι$^{-1}$을 첨가한 MS 배지에서 shoots및 roots 형성률이 각각 20, 30%로서 가장 양호한 것으로 나타났다. 1/2 MS배지의 경우 zeatin 1.0mgι$^{-1}$에서 shoots 형성률이 67 %, B5 배지에 있어서 zeatin 3.0 mgι$^{-1}$ 처리에서 33 %로 가장 양호한 것으로 나타났다. 배지에 따른 식물 생장조절제 처리에 따른 식물체 분화율은 MS 배지에서는 2,4-D 0.5 mgι$^{-1}$, 1/2 MS 배지에서 zeatin 1.0 mgι$^{-1}$ 및 B5 배지에서 reatin 3.0 mgι$^{-1}$에서 자장 가장 많은 100, 193, 280 및 310%의 분화된 식물체를 얻을 수 있었다. 전반적으로 야생화인 처녀치마의 잎 조직으로부터 multiple shoots을 유도하여 대량증식을 위한 목적으로는 B5 배지에 생장조절제인 zeatin 3.0 mgι$^{-1}$을 첨가시키는 것이 가장 효과적인 것으로 나타났다.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 1986년도 추계학술대회
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• pp.527.3-527
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• 1986

Several factors predicted to affect the protoplast formation and regeneration were investigated. The optimum lysozyme, casamino acid and PVP concentration were 0.5 (mg/$m\ell$), 0.1 (%) and 1.5(%). In B. pumilus, Penicillin-G treatment concentration was 0.3 (U/$m\ell$) and optimum treatment period was transit log. phase. And in the case of Celm. fimi, 0.3 (U/$m\ell$) and initial log. phase. Osmotic stabilizer and di-cation for OSM medium of B.pumilus and Gelm .fimi were 25mM CaCl2, 0.5M sodium sucinate and 50mM MgCl$_2$, 100mM CaCl$_2$, 0.4M sodium succinate. The regeneration frequency of B.pumilus and Celm. fimi were 14.6(%) and 6.9(%).

• 한국초전도ㆍ저온공학회논문지
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• 제16권2호
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• pp.36-41
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• 2014

Temperature dependence of magnetic moment (m-T) and the magnetization (M-H) at 5 K and 20 K of the in situ processed $MgB_2$ bulk pellets with/without carbon (C) doping were examined. The superconducting critical temperature ($T_c$), the superconducting transition width (${\delta}T$) and the critical current density ($J_c$) were estimated for ten test samples taken from the $MgB_2$ bulk pellets. The reliable m-T characteristics associated with the uniform $MgB_2$ formation were obtained for both $MgB_2$ pellets. The $T_cs$ and ${\delta}Ts$ of all test samples of the undoped $MgB_2$ were the same each other as 37.5 K and 1.5 K, respectively. The $T_cs$ and ${\delta}Ts$ of the C-doped $MgB_2$ were 36.5 K and 2.5 K, respectively. Unlike the m-T characteristics, there existed the difference among the M-H curves of the test samples, which might be caused by the microstructure variation. In spite of the slight $T_c$ decrease, the C doping was effective in enhancing the $J_c$ at 5 K.

• Progress in Superconductivity
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• 제12권1호
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• pp.1-5
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• 2010

In this work we synthesized both MgB2 and Carbon doped MgB2 superconductor with Ag addition via high energy milling and substituent heat treatment. Heat treatments were performed at $900\;^{\circ}C$ for 30 min in flowing Ar gas. We varied amount of Ag powder. In a range of Ag powder was 0~5wt%. The effect of Ag was correlated with superconducting properties. The results show a slight decrease in critical temperature ($T_c$) and a reduction of critical current density ($J_c$) at high fields for the Ag-doped samples as compared to the un-doped samples. Reduction of $J_c$ may be due to the formation of MgAg compound.