• Title/Summary/Keyword: NBT

Search Result 135, Processing Time 0.027 seconds

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

  • Lee, Eunbin;Hong, Jungil
    • Korean Journal of Food Science and Technology
    • /
    • v.54 no.1
    • /
    • pp.1-7
    • /
    • 2022
  • Riboflavin (Rb), in the presence of methionine (Met) under light, generates superoxide radicals that can reduce nitro blue tetrazolium (NBT) to its corresponding formazan. The Rb-Met/NBT system has been used to measure the superoxide dismutase (SOD)-like activities of various antioxidants. However, the reaction mechanisms have not been clearly defined, and the assay conditions are not consistent. In this study, the effects of different photosensitizers and amino acids on NBT reduction in different solvents were investigated. NBT reduction in the Rb-Met/NBT system was more pronounced in phosphate-buffered saline, compared to distilled water or Tris (pH 7.5); histidine (His) instead of Met also led to considerable Rb-induced NBT reduction. Among the photosensitizers, methylene blue with His caused potent NBT reduction in Tris. Rb-induced NBT reduction combined with Met or His was quantitatively inhibited by SOD or gallic acid, but did not affect MB-induced reduction sensitively.

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

  • Mhin, Sungwook;Lee, Jung-Il;Ryu, Jeong Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.25 no.4
    • /
    • pp.160-165
    • /
    • 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.

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

  • Kim, Hong-Suk;Chung, Soon-Kyu;Jung, Jin
    • Applied Biological Chemistry
    • /
    • v.36 no.5
    • /
    • pp.364-369
    • /
    • 1993
  • Triton X-100 enhances to a marked extent the analytical sensitivity of the nitrobluetetrazolium (NBT) reduction method for the assay of superoxide$(O^-_{\.{^.2}})$ production. In the present work, it was attempted to elucidate the physicochemical nature of this Triton X-100 effect, focusing on not only the surfactant-caused stabilization of the water-insoluble formazan colloid but also the kinetic competition between the $NBT-O^-_{\.{^.2}}$ reaction and the autodisproportionation of concommitantly occuring in aqueous media. The measurements of formazan and $H_2O_2$ formed in a number of reaction systems, as prepared by vortex-mixing potassium superoxide dissolved in an aprotic solvent with aqueous solutions of NBT, revealed that Triton X-100 exerts its effect both through preventing formazan colloid from aggregation and thereby increasing the formazan absorbance and through suppressing the autodisproportionation reaction of $O^-_{\.{^.2}}$. It also turned out that the relative shares of the colloid stabilization effect and the kinetic effect in the contribution to the sensitivity amplification of the NBT method are dependent upon the reaction conditions, particulary the molar concentration ratio of NBT to $O^-_{\.{^.2}}$ in the reaction systems.

  • PDF

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

  • Park, Min-Seok;Yoo, Young-Bae;Moon, Byung-Kee;Son, Se-Mo;Chung, Su-Tae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2004.07b
    • /
    • pp.894-897
    • /
    • 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.

  • PDF

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

  • Moon Kyoung-Seok;Kang Suk-Joong
    • Journal of Powder Materials
    • /
    • v.13 no.2 s.55
    • /
    • pp.119-123
    • /
    • 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.

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

  • Park, Eun-Jung;Kim, Jin-Woong
    • Korean Journal of Pharmacognosy
    • /
    • v.28 no.4
    • /
    • pp.225-232
    • /
    • 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.

  • PDF

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

  • Yoo Young-Bae;Park Min-Seok;Son Se-mo;Chung Su-Tae
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.19 no.2
    • /
    • pp.176-180
    • /
    • 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.

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

  • Lee, Byoungwan;Luo, Haosu;Kim, Jung Kyu
    • Ceramist
    • /
    • v.23 no.1
    • /
    • pp.101-109
    • /
    • 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.

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

  • Yang, Min Seung;Lee, Sung Moo
    • Current Photovoltaic Research
    • /
    • v.5 no.3
    • /
    • pp.100-104
    • /
    • 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
    • /
    • v.21 no.1
    • /
    • pp.41-45
    • /
    • 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.

  • PDF