• 제목/요약/키워드: NBT

검색결과 137건 처리시간 0.027초

다양한 감광제와 아미노산의 조합 반응에서 nitro blue tetrazolium의 환원특성 평가 (Reduction of nitro blue tetrazolium by combined reaction of various photosensitizers with amino acids)

  • 이은빈;홍정일
    • 한국식품과학회지
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    • 제54권1호
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    • pp.1-7
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    • 2022
  • 본 연구에서는 형광등 빛 조사 하에 각종 감광제와 아미노산의 조합에 의한 NBT의 환원 특성을 조사하였다. 기존 SOD 활성 측정에 이용된 Rb-Met 반응계는 증류수나 Tris보다는 PBS 용매 상에서 가장 우수한 효과를 나타냈다. 빛 조사 하에 Rb에 의한 NBT 환원을 위해서는 Met과 His 등의 아미노산이 필요하며, 감광제로서는 isoalloxazine 계열의 Rb와 thiazine 계열의 MB가 효과적인 환원 반응을 유도했다. 하지만 각종 감광제나 아미노산의 조합, 그리고 반응 용매에 따라 NBT 환원정도가 상이하며, 특히 Rb-Met in PBS와 MB-His in Tris 반응계가 가장 큰 반응을 유도하였다. Rb에 의해 유도된 NBT 환원반응은 SOD 및 gallic acid에 의해 효과적으로 저해되었으나, Tris 상에서 MB-His에 의한 NBT 환원은 SOD 및 gallic acid에 의한 저해효과가 미미하여 Rb와는 다른 기작에 의해 NBT 환원이 유도되는 것으로 보인다. 본 결과는 감광제와 아미노산에 따라 빛 조사 하에 다양한 상호작용이 발생하며, NBT 환원을 유도하는데 superoxide anion 뿐만 아니라 다른 요인도 관여할 수 있음을 시사한다.

Processing, structure, and properties of lead-free piezoelectric NBT-BT

  • Mhin, Sungwook;Lee, Jung-Il;Ryu, Jeong Ho
    • 한국결정성장학회지
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    • 제25권4호
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    • pp.160-165
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    • 2015
  • Lead-free piezoelectric materials have been actively studied to substitute for conventional PZT based solid solution, $Pb(Zr_xTi_{1-x}O_3)$, which occurs unavoidable PbO during the sintering process. Among them, Bismuth Sodium Titanate, $Na_{0.5}Bi_{0.5}TiO_3$ (abbreviated as NBT) based solid solution is attracted for the one of excellent candidates which shows the strong ferroelectricity, Curie temperature (Tc), remnant polarization (Pr) and coercive field (Ec). Especially, the solid solution of rhombohedral phase NBT with tetragonal perovskite phase has a rhombohedral - tetragonal morphotropic phase boundary. Modified NBT with tetragonal perovskite at the region of MPB can be applied for high frequency ultrasonic application because of not only its low permittivity, high electrocoupling factor and high mechanical strength, but also effective piezoelectric activity by poling. In this study, solid state ceramic processing of NBT and modified NBT, $(Na_{0.5}Bi_{0.5})_{0.93}Ba_{0.7}TiO_3$ (abbreviated as NBT-7BT), at the region of MPB using 7 % $BaTiO_3$ as a tetragonal perovskite was introduced and the structure between NBT and NBT-7BT were analyzed using rietveld refinement. Also, the ferroelectric and piezoelectric properties of NBT-7BT such as permittivity, piezoelectric constant, polarization hysteresis and strain hysteresis loop were compared with those of pure NBT.

NBT 환원방법에 의한 superoxide 라디칼의 검량에 미치는 Triton X-100 효과에 대한 재평가 (Reevaluation of. the effect of Triton X-100 on the assay of superoxide radical by the nitrobluetetrazolium reduction method)

  • 김홍석;정순규;정진
    • Applied Biological Chemistry
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    • 제36권5호
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    • pp.364-369
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    • 1993
  • 널리 이용되는 검량방법중의 하나인 NBT 환원방법은 계면활성제인 Triton X-100의 존재하에서 그 측정감도가 크게 증폭된다. 본 연구는 이러한 Triton X-100 효과의 물리화학적 본질을 이해하기 위하여 수행하였으며, 이를 위하여 이 계면활성제가 NBT의 환원생성물인 불용성 formazan 콜로이드를 안정화시키는 효과와 수용액 중에서 동시에 진행되는 두 반응 $(NBT-O^-_{\.{^.2}}$ 산화환원 반응과 $O^-_{\.{^.2}}$의 disproportionation반응) 간의 경쟁관계에 미치는 속도론적 영향에 촛점을 맞추었다. Triton X-100 유무 조건하에서 $KO_2-DMSO$ 용액과 $K-PO_4$ 완충용액에 녹인 여러가지 농도의 NBT 용액을 빠르게 혼합하고, 이때 생성된 formazan과 $H_2O_2$를 각각 정량한 결과, 이 계면활성제는 formazan 콜로이드를 안정화 시킴으로써 결과적으로 formazan의 흡수도를 상승시키는 효과를 보일뿐만 아니라 $O^-_{\.{^.2}}$의 자발적인 dismutation을 억제하는 결과를 초래함을 확인하였다. 또한 종합적인 Triton X-100의 효과에 대한 콜로이드 안정화 효과와 속도론적 효과의 상대적 기여도는 실험조건에 따라 바뀌는데 특히 반응계의 $NBT/O^-_{\.{^.2}}$ 농도비율에 크게 좌우되는 것으로 밝혀졌다.

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졸-겔법으로 $LaNiO_3$ 전극에 증착된 $(Na_{0.5}Bi_{0.5})TiO_3$ 박막의 배향성 (Orientation of $(Na_{1/2}Bi_{1/2})TiO_3$ thin films deposited on $LaNiO_3$ electrodes by sol-gel methode)

  • 박민석;유영배;문병기;손세모;정수태
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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    • pp.894-897
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    • 2004
  • Sodum bismuth titanate $(Na_{0.5}Bi_{0.5}TiO_3$ or NBT) thin films coated on the $LaNiO_3$ (LNO) electrode by sol-gel methode and rapid thermal annealing (RTA) technique. The NBT (NBT/LNO/Si) thin films examined by x-ray diffraction (XRD). The orientation of NBT was observed for films coated at $900^{\circ}C$, 5 min and $600^{\circ}C$, 60 min. Filed emission scanning electron microscopy (FE-SEM) showed uniform surface composed of grains. The grain size of NBT thin films increased with increasing annealing temperature.

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Na1/2Bi1/2TiO3-BaTiO3 계에서 입자모양과 입자성장 거동 (Grain Shape and Grain Growth Behavior in the Na1/2Bi1/2TiO3-BaTiO3 System)

  • 문경석;강석중
    • 한국분말재료학회지
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    • 제13권2호
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    • pp.119-123
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    • 2006
  • The grain growth behavior of $0.95Na_{1/2}Bi_{1/2}TiO_{3}-0.05BaTiO_{3}$ (NBT-5BT) has been investigated with respect to the grain shape. The powder compacts of NBT-5BT were sintered at 1200 for various times. The corresponding equilibrium shape was a round-edged cube with flat {100}-faces. Abnormal grains were not observed in the specimens sintered for 1 to 12 h but abnormal grains appeared when sintered for 24 h. Before the formation of abnormal grains, a valley was observed in the measured grain size distribution of NBT-5BT, showing that the grain size distribution was a combination of two unimodal distributions. The present result suggests that the grain growth in NBT-5BT was governed by the growth of facet planes which would occur via 2-dimansional nucleation and growth.

생약으로부터 세포분화유도물질의 검색 및 분리 및 분리 (I) (Screening and Isolation of the Cell Differentiation Inducers from Medicinal Plants (I))

  • 박은정;김진웅
    • 생약학회지
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    • 제28권4호
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    • pp.225-232
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    • 1997
  • 300 extracts derived from 100 plants were tested for their potential to induce HL-60 cell differentiation using NBT assay and NSE/SE staining methods. Morphological changes from suspended to adherent state of the cells were also observed by microscopic examination. In result, 55 extracts induced cell differentiation into monocyte/macrophage lineage in the NBT and the NSE assay.

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LaNiO3 전극위에 (100)으로 배향된 (Na0.5Bi0.5)TiO3 박막의 성장 (Growth of Highly (100) Oriented (Na0.5Bi0.5)TiO3 Thin Films on LaNiO3 Electrode)

  • 유영배;박민석;손세모;정수태
    • 한국전기전자재료학회논문지
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    • 제19권2호
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    • pp.176-180
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    • 2006
  • [ $(Na_{0.5}Bi_{0.5})TiO_3$ ][NBT] thin films were prepared on a highly (100) oriented $LaNiO_3[LNO]$ by sol-gel process. X-ray diffraction patterns of the NBT films annealed above $600^{\circ}C$ for 5 minutes have confirmed a highly (100) oriented growth and pseudocubic structure (a=3.884${\AA}$). The (l00) orientation factor increased from 90 to $99\%$ with increasing soaking time from 5 to 60 minutes at $600^{\circ}C$. The NBT films ($600^{\circ}C$/5 min,) have a flat and dense microstructure with large columnar grains, and their grain size are about 44 nm. The Au/NBT/LNO/Si hetero structure sample show a ferroelectric properties.

납이 포함되지 않은 압전 특성의 (Na1/2Bi1/2TiO3)(1-x)-(BaTiO3)x 상전이 거동 연구 (Phase Transition Behaviors of Lead-Free Piezoelectric (Na1/2Bi1/2TiO3)(1-x)-(BaTiO3)x)

  • 이병완;;김정규
    • 세라미스트
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    • 제23권1호
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    • pp.101-109
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    • 2020
  • In this study, the phase transition behaviors of lead-free (Na1/2Bi1/2TiO3)(1-x)-(BaTiO3)x (NBT-BT) are investigated by using Brillouin spectroscopy. The elastic properties, sound velocity and absorption coefficient of NBT-BT are characterized as a function of temperature along different crystallographic axes. The temperature dependences of the elastic constants of NBT-BT near the morphotropic phase boundary are determined for the first time. The unpoled NBT-BT single crystals exhibits the typical relaxor behaviors, presenting broad acoustic and dielectric anomalies. The application of electric field induced discontinuous changes in the elastic properties at ~110℃, which indicates field-induced phase transition occurred. The electric field also changes the dielectric constant from more relaxor-like to ferroelectric-like dielectric behavior.

우리나라 전력시장에서 경제성 DR의 NBT 및 낙찰 관계 분석 (A Study on Economic Demand Response NBT and Performance)

  • 양민승;이성무
    • Current Photovoltaic Research
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    • 제5권3호
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    • pp.100-104
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    • 2017
  • This paper analyzes the correlation between Net Benefit Test (NBT) and System marginal price (SMP), which has a significant impact on the allocation of demand response (DR) resources in resource scheduling and commitment (RSC) process, based on the performance data of the demand resource market which has been established in 2014. Demand resources compete with generation resources in the RSC process, and it is prescribed to use demand resources only when net benefit occurs. Analysis result shows that the larger the SMP than the Net Benefit Threshold Price (NBTP), the more the winning bid of demand response resource was. It is interpreted that the introduction of NBT in DR market is justified. The demand resource market has been steadily growing. It is required to expand the scope of resources up to the small-sized DR, and to expand the functionalities of demand resources not only in the current energy market but also in the reserve market in the future. In order for that, institutional improvements are required.

Induction of Differentiation of the Human Histocytic Lymphoma Cell Line U-937 by Hypericin

  • Kim, Joo-Il;Park, Jae-Hoon;Park, Hee-Juhn;Choi, Seung-Ki;Lee, Kyung-Tae
    • Archives of Pharmacal Research
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    • 제21권1호
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    • pp.41-45
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    • 1998
  • Hypericin, a photosensitizing plant pigment, was found to be a potent inducer of differentiation of human myeloid leukemia U-937 cells. At a concentration of $0.2{\mu}M$, hypericin exhibited 50% growth inhibition. An effect on cell differentiation by hypericin was assessed by its ability to induce phagocytosis of latex particles, and to reduce nitroblue tetrazolium (NBT). Approximately 51% of $0.2{\mu}M$ hypericin-treated cells were stained with NBT and 63% showed phagocytic activity. In order to establish whether hypericin induces differentiation of U-937 cells to macrophage or granulocyte, esterase activities and cell sizes were measured. When U-937 cells were treated with $0.2{\mu}M$ and $0.15{\mu}M$ of hypericin, the .alpha.-naphthyl acetate esterase activity was increased by 38.4% and 48.1%, respectively, but naphthol AS-D chloroacetate esterase activity was not influenced. The size of hypericin-treated cells in terms of cell mass was larger than that observed in untreated cells as determined by flow cytometry. Protein kinase C (PKC) inhibitor, NA-382, decreased the NBT reducing activity of hypericin, whereas a cAMP-dependent protein kinase A (PKA) inhibitor, H-89, did not show any influence on the differentiations. These results indicate that hypericin triggers differentiation toward monocyte/macrophage lineage by PKC stimulation.

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