• 한국세라믹학회지
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• 제51권5호
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• pp.477-480
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• 2014

An $Al_2O_3$-CuO-ZnO (ACZ) precursor powder was synthesized by a facial sol-gel process using a nonionic surfactant span 80 as the chelating agent to improve the surface area and morphology. When creating a hydrogen membrane, several kinds of properties are required, such as easy dissociation of hydrogen molecules, fast hydrogen diffusion, high hydrogen solubility, and resistance to hydrogen embrittlement. ACZ-Ni composite membranes (cermet) were prepared with this precursor and pure Ni powder via the hot press sintering (HPS) method. The ACZ powder was characterized by XRD, BET, and FE-SEM. Hydrogen permeation experiments were performed by Sievert's type of hydrogen permeation membrane equipment. The hydrogen permeability of ACZ/Ni 10 wt% and ACZ/Ni 20 wt% was obtained as 7.2 and $10molm^{-2}s^{-1}$ at RT, respectively. These values of the corresponding membranes were slightly increased with increasing pressures.

• Biomolecules & Therapeutics
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• 제9권1호
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• pp.40-45
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• 2001

The activity of taurine transporter is affected by various extracellular stimuli such as ion, hormone and stress. To assess effects of steroid hormones antral cyclosporin A (CsA) on the taurine transporter activity, murine monocytic RAW264.7 cell line was stimulated with dexamethasone (DM), triamcinolone (TA), cortisone (CS), hydrocortisone (HCS), prednisone (PSN), prednisolone (PSL) and methylprednisolone (MPSL) in the presence of 12-0-tetradecanoylphorbol-13-acetate(TPA). Treatment of TPA on the cell line led to significant reduction of taurine transporter activity. However, in case of stimulation of the cells with steroid hormones in the presence of TPA, all of them recovered TPA-induced reduction of the taurine transporter activity. Treatment of the cells with CsA led to significant reduction of the taurine transporter activity. Ionomycin (IM) recovered the reduced taurine transporter activity by CsA, but failed in the presence of EDTA, a calcium chelating agent. These results showed that glucocorticoid hormone recovered TPA-induced reduction of taurine transporter activity and that IM recovered CsA-induced reduction of the transporter activity by increasing intracellular free $Ca^{++}$ concentration.n.

• Journal of Applied Biological Chemistry
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• 제60권1호
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• pp.35-39
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• 2017

Turkey has a very rich fungal flora due to its phytogeographical position. The screening of chemical content and active substances of mushrooms becomes an important subject not only for Turkey but also for all over the world. In the last decade, Analyses on phytochemical and biological activity of fungi have gradually increased as a result of improvement in the number and quality of facilities. In the scope of the present research, four medicinal mushrooms; Morchella elata, Lactarius volemus, Cantharellus cibarius and Tricholoma terreum were analyzed for their fatty acid compositions and antioxidant capacities. The fungal species have been found with unsaturated fatty acid/saturated fatty acid ratio of 6.73 for Morchella elata, 4.12 for Lactarius volemus, 5.21 for Cantharellus cibarius, 3.73 for Tricholama terrum. In addition, the concentration of malondialdehyde which was an indicator of lipid peroxidation was also determined in these species. According to the results, free radical scavenging activity of Morchella elata and Lactarius volemus were found higher than the other species. Any of the mushroom species investigated were found having very high metal chelating activity. The results showed that the extract of Morchella elata and Lactarius volemus exhibited significant antioxidant activities. Hence, the mushrooms have a potential to be a natural antioxidant in food industries as antioxidant agent.

• Journal of Microbiology and Biotechnology
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• 제23권11호
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• pp.1554-1559
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• 2013

A protease produced by Bacillus polyfermenticus SCD was purified and characterized as a new detergent material. The protease was purified from supernatant produced by B. polyfermenticus SCD, by ammonium sulfate precipitation, ion-exchange chromatography on a DEAE-Sephadex A-50, and finally gel filtration chromatography on Sephadex G-50. The molecular mass of this enzyme was 44 kDa based on SDS-PAGE. The optimum temperature and pH were $50^{\circ}C$ and pH 8.0. The ranges of its stability to the pH and temperature were 7.0 to 9.0 and under $40^{\circ}C$, respectively. The enzyme was highly stable in the presence of the surfactants like Triton X-100 (0.1%), showing a 2-fold increase in its proteolytic activity. However, the enzyme was slightly inhibited by the chelating agent EDTA (1 mM). The enzyme has a maximum activity at $50^{\circ}C$ and the activity can be increased by surfactants such as Triton X-100 and Tween 80.

• 한국세라믹학회지
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• 제31권7호
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• pp.795-803
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• 1994

Ferroelectric BaTiO3 thin film was produced using BaTi-ethoxide sol. This sol was prepared from BaTi-ethoxide by a partial hydrolysis with ammonia as a basic catalyst and ethylene glycol as a chelating agent. BaTiO3 thin film was prepared from three continuous spin-coating layers of the sol on bare Si(100) wafer at 2500 rpm followed by pyrolysis at $700^{\circ}C$ for 30 min. After the heat treatment, the film was 0.200$\pm$0.010 ${\mu}{\textrm}{m}$ thick and its grain size was 0.059 ${\mu}{\textrm}{m}$. On the other hand, electrical properties were measured for BaTiO3 thin film separately prepared on Au-deposited silicon wafer. The dielectric constant and loss of the BaTiO3 thin film at room temperature was 150~160 and 0.04 respectively, which was measured at 10 kHz and oscillation level of 0.1 V. In the measurements of the dielectric properties at high temperatures, it was observed that the capacitance of the thin film increases steeply, while the dielectric loss reaches maximum around 1$25^{\circ}C$, which corresponds a phase transition from tetragonal to cubic BaTiO3.

• 공업화학
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• 제5권1호
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• pp.149-159
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• 1994

금속의 용매 추출에 amidoxime의 추출제로서의 특성을 검토하기 위하여 benzamidoxime 및 phenylacetamidoxime에 의한 금속 추출평형 및 추출속도에 관한 실험 및 이론적 고찰을 하였다 Cu, Pb, Zn 및 Cd 등 단독 금속계와 혼합 금속계에 대한 amidoxime-클로로포름에 의한 추출에서 추출비와 수소이온 농도 및 추출제 농도간의 상관관계로부터 추출기구와 추출성을 검토하고, 수상측 경막 내 확산 방정식으로부터 도출된 이론적 속도식과 실험적 속도식을 비교함으로써 초기 추출 속도식은 $R_o=k{\overline{C}}_{HRO}(C_{Mo}/C_{Ho})^{1/2}$로 표시할 수 있었으며, 추출과정의 율속 단계를 고찰하였다. amidoxime에 의한 Cu의 추출 화학종은 ${\overline{CuR_2}}$의 형이었다.

• 한국세라믹학회지
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• 제40권12호
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• pp.1154-1158
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• 2003

Hydrothermal deposition of hydroxyapatite coatings on $Al_2$O$_3$ substrates was studied using aqueous solutions of Ca(NO$_3$)$_2$ㆍ4$H_2O$ and (NH$_4$)$_2$HPO$_4$ containing EDTA disodium salt as a chelating agent for $Ca^{2+}$. For the precipitation of the coatings the EDTA-Ca$^{2+}$ chelates were dissociated thermally at 20$0^{\circ}C$ or decomposed by oxidation with $H_2O$$_2$ at 9$0^{\circ}C$. Scanning electron microscopy and X-ray diffraction were used to investigate the deposition behavior and the phase of the coatings. Hydroxyapatite coatings were not deposited with the thermal dissociation method, whereas uniform deposition of the coatings (about 0.7 $\mu\textrm{m}$ thickness) was obtained with the oxidative decomposition method. The coatings consisted of fine rod-like hydroxyapatite crystals (hexagonal structure) with 60-80 nm diameters, having some preferred orientation with their length (i.e., the c axis) perpendicular to the substrate.ate.

• Journal of Microbiology and Biotechnology
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• 제15권1호
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• pp.192-196
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• 2005

Abstract Oligotrophic microbial fuel cells (MFCs) were tested for the continuous monitoring of low biochemical oxygen demand (BOD) by using artificial wastewater, containing glucose and glutamate, as check solution. Ten times diluted trace mineral solution was used to minimize the background current level, which is generated from the oxidation of nitrilotriacetate used as a chelating agent. The feeding rate of 0.53 ml/min could increase the sensitivity from 0.16 to 0.43 ${\mu}$A/(mg BOD/l) at 0.15 ml/min. The dynamic linear range of the calibration curve was between 2.0 and 10.0 mg BOD/l, and the response time to the change of 2 mg BOD/l was about 60 min. The current signal from an oligotroph-type MFCs increased with the increase in salts concentration, and the salt effect could be eliminated by 50 mM phosphate buffer.

• 한국미생물·생명공학회지
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• 제18권4호
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• pp.360-367
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• 1990

토양으로부터 rutin을 유일한 탄소원으로 생육하는 세균을 분리하여 그 중 rutin 가수분해활성이 높은 MT-57균을 Arthrobacter sp.로 동정하였다. Arthrobacter sp.MT-57에서 수 종류의 rutin 가수분해효소가 확인되었으며 이들 중 rutinosidase를 전기영동상 단일한 효소 단백질까지 정제하였다. Rutinosidase으 분자량은 SDS page와 gel filtration으로 부터 42,000의 단량체로 추정 되었다. 효소반응의 최적 pH와 온도는 pH 7.5와 $45^{\circ}C$였으며, 20분간 열처리하였을 때 $50^{\circ}C$까지 안정하였다.

• 대한화학회지
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• 제19권6호
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• pp.463-467
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• 1975

Tetrahydrofuran(THF)중에서 질산코발트(II)를 개시제로 사용하여 methyl methacrylate(MMA)의 중합반응을 연구하였다. 반응속도론적 연구 결과로 다음과 같은 중합속도식을 얻었다. $R_p=k\;[질산코발트(II)]^{0.5}\;[MMA]^{1.5}$ Chelate를 잘 형성하는 옥살산이 중합속도에 미치는 영향을 고려해 보면, 단위체인 MMA가 질산코발트(II)와 배위착물을 형성한다는 것을 추론할 수 있었다. 또 중합계의 겉보기 총 활성화에너지는 14.0kcal/mole이라는 것을 알았다.