• 분석과학
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• 제5권2호
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• pp.199-202
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• 1992

$BF_2$를 50keV, 90keV로 에너지를 달리하여 주입한 실리콘 기판에 타이타늄을 sputter하여 Ti-slicide를 형성한 시편과 composite target을 사용하여 Ti-silicide를 형성한 시편을 준비하였다. Ti-silicide 형성시 boron의 거동을 SIMS(secondary ion mass spectrometry)로 분석하였다. Metal-Ti target을 사용한 경우 Ti-silicide 형성시 불순물들이 재분포하였으며 이온 주입 에너지가 작은 경우 심한 out-diffusion이 발생하였다. 한편 Composite target을 사용한 경우 거의 재분포가 발생하지 않고 안정된 boron의 분포를 보였다.

• 농업과학연구
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• 제39권2호
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• pp.255-261
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• 2012

A bacterium AB-55, isolated from waste mushroom bed of Agaricus bisporus in Sukseong-myeon, Buyeo-gun, Chungcheongnam-do, Korea, was screened onto xylan agar congo-red plate by the xylanolysis method and was used to produce an xylanase in shaker buffle flask cultures containing oat spelt xylans. The phylogenetic analysis using 16S rRNA gene sequence data showed that the strain AB-55 had the highest homology (99.0%) with Bacillus subtilis and it was named as Bacillus subtilis AB-55. A xylanase was purified by ammonium sulfate precipitation (50~80%), gel filtration on sephacryl S-300, and ion exchange chromatography on DEAE sepharose FF. The molecular weight of the xylanase was estimated as 44 kDa by SDS-PAGE. Optimal pH and temperature for the xylanase activity was pH 7 and $50^{\circ}C$, respectively. N-terminal amino acid sequence of the enzyme was identified as Ser-Ala-Val-Lys-His-Gly-Ala-Ile-Val-Phe. The substrate specificity of the enzyme exhibited that it hydrolyzed efficiently oat spelt xylan as well as beechwood xylan, but showed no activity against Avicel and carboxymethyl clellulose (CMC). The enzyme activity was enhanced by $Fe^{2+}$ and $Mn^{2+}$ whereas was entirely inhibited by $Hg^+$.

• Journal of Chest Surgery
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• 제30권11호
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• pp.1136-1138
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• 1997

승모판막 폐쇄부전증으로 승모판막 치환술을 받은 45세 남자가 확장성 심근증으로 심장이식수술을 받았다. 환자는 수술전 면역억제를 위하여 cyclosporine 400 mg, Immuran 250 mg과 Solumedrol 500 mg을 투약하였 다 술후 cyclosporine을 2 mg/kg/day로 정주했는데 술후 8시간이 지나도 혼수상태가 지속되어 cyclosporine을 1 mg/kg/day로 감량하였다. 당시 혈장내 cyclosporine농도는 345$\mu\textrm{g}$/L, 크레아티닌 수치는 1.8 mg/dl였으며 마그 네슘 수치는 정상수준이 였다. 환자의 의식은 술후 31시간째 완전히 회복되었으나 술후 36시간경부터 전신근 력약화, 초조감, 환청 및 환각을 호소하였다. 신경증상들은 술후 4일째 정상으로 회복되었으며, 환자는 술후 28일째 퇴원하였고 12개월째 후유증은 보이지 않고 있다.

• 한국약용작물학회지
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• 제24권3호
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• pp.237-245
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• 2016

Background: Cyanazine is used as a pre-emergent herbicide once during the growing season to control weeds of many upland crops worldwide. This study aimed to establish a method to determined cyanazine residue levels in major medicinal crops by using high performance liquid chromatography-UV detection/mass spectometry (HPLC-UVD/MS). Methods and Results: Cyanazine residue was extracted with acetone from the raw products of four representative medicinal plants - Scutellaria baicalensis, Paeonia lactiflora, Platycodon grandiflorum and Angelica gigas. The extract was diluted with a large volume of saline water and directly partitioned into dichloromethane to remove polar co-extractives in the aqueous phase. It was then purifined using optimized Florisil column chromatography. HPLC analysis conducted using an octadecylsilyl column allowed the successful separation of cyanazine from co-extractives of the samples, and the amount was sensitively quantified by ultraviolet absorption at 225 nm with no interference. The accuracy and precision of the proposed method were validated by conducting recovery experiments on each medicinal crop sample fortified with cyanazine at two concentration levels per crop in triplicate. Conclusions: The mean recoveries ranged from 91.2% to 105.3% for the four representative medicinal crops. The coefficients of variation were less than 10%, irrespective of the sample types and fortification levels. The limit of quantification of cyanazine was 0.02 mg/kg as verified by the recovery experiment. A confirmatory method was performed by liquid chromatography/MS using selected-ion monitoring technique to clearly identify the suspected residue.

• Applied Biological Chemistry
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• 제45권3호
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• pp.179-184
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• 2002

한국산 검정콩 종피의 천연색소로의 이용가능성을 알아보기 위하여 온도, 당류, 유기산류, 비타민 C 그리고 금속 이온의 영향을 살펴보았다. 검정콩 색소의 열안정성은 다른 안토시아닌 계열의 색소와 비교할 때 유사하거나 더 안정한 것으로 나타났다. 당류의 영향에서는 타 색소와는 달리 농색화 현상은 일어나지 않았고 저장성에서는 모두 포도당에서 양호하였다. 유기산에서는 모든 첨가구에서 색의 강도가 증가하였으며 비타민 C 첨가의 경우 안토시아닌 색소에 부정적인 영향을 나타내었고 금속이온의 영향에서는 $Cu^{2+}$와 $Zn^{2+}$ 이온에서 안정하였으며 $Mn^{2+}$에서는 불안정하였다. 이상의 결과를 종합해 볼 때 검정콩 종피색소는 pH 3에서 다른 색소와 비교하여 상당히 안정한 색소임을 알 수 있었다.

• Preventive Nutrition and Food Science
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• 제13권3호
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• pp.196-203
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• 2008

Hwangtae, dried Alaska pollack, is a major storage product in the fish processing industry. Hwangtae is prepared by removing the internal organs and drying outdoors during the cold witner months by allowing it to thaw during the daytime and re-freeze at night under sub-zero ($-10^{\circ}C$) conditions and gradually dry from December until the next April for around 5 months from Myungtae. In this study, ground Hwangtae was hydrolyzed using two proteolytic enzymes (pepsin and alcalase) which produced five soluble active peptides from Hwangtae (yellowish dried Pollack, Theragra chalcogramma) protein. Two different peptides with strong antioxidative activity were isolated from the hydrolysate using consecutive chromatographic methods of Sephadex G-25 gel, ion-exchange chromatography on a Sepharose-Sephadex C-25 gel, and high-performance liquid chromatography. The isolated peptides, APO1 and APO2, were composed of 16 and 13 amino acid residues, respectively. Both peptides contained a Gly residue at the C-terminus and the repeating motif Gly-Pro-Hyp. The peptide with a molecular weight less than 1,000 Daltons (APACE) obtained from enzymatic hydrolysates of Hwangtae exhibited the highest ACE inhibitory activity. The APACE peptides was composed of 4 amino acid residues (Gly-Leu-Leu-Pro). These results suggest that Hwangtae hydrolysates could be a good source of peptides with ACE inhibitory activity. Biochemical analysis indicated that two 70 kDa peptides (APG1 and APG2) isolated from the hydrolysate had gelatinoytic activity, which was shown to be a calcium dependent protease type as showed by gelatin SDS PAGE.

• 멤브레인
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• 제21권1호
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• pp.39-45
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• 2011

원자전달 라디칼 중합(ATRP)에 의해 poly(vinyl chloride) (PVC) 주사슬과 poly(styrene sulfonic acid) (PSSA) 곁사슬로 되어있는 양쪽성 PVC-g-PSSA 가지형 공중합체를 합성하였다. 합성된 고분자 전해질막을 10 wt% $AgNO_3$ 수용액에 담가 은이온으로 이온교환을 하였으며, 환원제를 통하여 은 나노입자를 성장시켰다. UV분광학과 XRD 분석을 통해 은 나노입자 성장을 확인하였다. 투과전자현미경(TEM) 분석결과 $NaBH_4$를 사용하였을 때 10~20 nm 크기의 은 나노입자를 얻는데 가장 효과적임을 알 수 있었다. 또한 은 나노입자의 성장은 환원제의 농도와 환원 시간에 크게 영향을 받았다.

• 한국식품영양과학회지
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• 제21권2호
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• pp.187-194
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• 1992

Rhizopus oryzae CJ-2114의 polygalacturonase 생성을 위한 최적조건은 수분이 60% 함유된 밀기울 배지에 1% albumin, 0.2% (NH$_4$)$_2$C$_2$O$_4$, 1% sorbitol을 첨가하여 96시간 배양시 최대활성을 나타내었으며, Sep-hadex G-75 및 G-150을 사용한 gel filtration과 DEAE-cellulose에 의한 이온교환 크로마토그라피를 통하여 이 효소를 11.13배 정제할 수 있었고, 수율은 40.3% 였다. 정제효소는 polyacrylamide gel 전기 영동에 의하여 단일밴드로 확인되었으며 분자량은 SDS-polyacryl-amide 전기영동에 의하여 47,000정도로 측정되었다. 효소의 결정구조는 표면이 거친 기둥모양을 형성하고 있었으며 아미노산 조상은 17종류로써 glutamic acid 함량이 198.74mg/g enzyme로 가장 많았다.

• Journal of Electrical Engineering and information Science
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• 제2권5호
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• pp.65-71
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• 1997

We present heterojunction solar cells with a structure of metal/a-Si:H(n-i-p)/poly-Si(n-p)/metal for the terrestrial applications. This cell consists fo two component cells: a top n-i-p junction a-Si:Hi cell with wide-bandgap 1.8eV and a bottom n-p junction poly-Si cell with narrow-bandgap 1.1eV. The efficiency influencing factors of the solar cell were investigated in terms of simulation an experiment. Three main topics of the investigated study were the bottom cell with n-p junction poly-Si, the top a-Si:H cell with n-i-p junction, and the interface layer effects of heterojunction cell. The efficiency of bottom cell was improved with a pretreatment temperature of 900$^{\circ}C$, surface polishing, emitter thickness of 0.43$\mu\textrm{m}$, top Yb metal, and grid finger shading of 7% coverage. The process optimized cell showed a conversion efficiency about 16%. Top cell was grown by suing a photo-CVD system which gave an ion damage free and good p/i-a-Si:H layer interface. The heterojunction interface effect was examined with three different surface states; a chemical passivation, thermal oxide passivation, and Yb metal. the oxide passivated cell exhibited the higher photocurrent generation and better spectral response.

• Macromolecular Research
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• 제16권6호
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• pp.549-554
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• 2008

Proton conducting crosslinked membranes were prepared using polymer blends of polystyrene-b-poly(hydroxyethyl acrylate)-b-poly(styrene sulfonic acid) (PS-b-PHEA-b-PSSA) and poly(vinyl alcohol) (PVA). PS-b-PHEA-b-PSSA triblock copolymer at 28:21:51 wt% was synthesized sequentially using atom transfer radical polymerization (ATRP). FT-IR spectroscopy showed that after thermal ($120^{\circ}C$, 2 h) and chemical (sulfosuccinic acid, SA) treatments of the membranes, the middle PHEA block of the triblock copolymer was crosslinked with PVA through an esterification reaction between the -OH group of the membrane and the -COOH group of SA. The ion exchange capacity (IEC) decreased from 1.56 to 0.61 meq/g with increasing amount of PVA. Therefore, the proton conductivity at room temperature decreased from 0.044 to 0.018 S/cm. However, the introduction of PVA resulted in a decrease in water uptake from 87.0 to 44.3%, providing good mechanical properties applicable to the membrane electrode assembly (MEA) of fuel cells. Transmission electron microscopy (TEM) showed that the membrane was microphase-separated with a nanometer range with good connectivity of the $SO_3H$ ionic aggregates. The power density of a single $H_2/O_2$ fuel cell system using the membrane with 50 wt% PVA was $230\;mW/cm^2$ at $70^{\circ}C$ with a relative humidity of 100%. Thermogravimetric analysis (TGA) also showed a decrease in the thermal stability of the membranes with increasing PVA concentration.