• Journal of Microbiology and Biotechnology
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• 제15권1호
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• pp.99-104
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• 2005

Microbacterium laevaniformans levansucrase synthesized various hetero-oligosaccharides by transferring fructosyl residue from sucrose to various saccharides as acceptors. The acceptor specificity test showed that reducing saccharides were more favorable acceptors than nonreducing saccharides. The transfructosylated product, fructosyl galactose, was produced in the presence of D-galactose as an acceptor. The chemical structure of the resulting fructosyl galactose was analyzed by yeast invertase and NMR, and identified as O-$\alpha$-D-galactosyl-(1${\to}$2)-$\beta$-D-fructofuranoside. These results indicate that the main transfructosylation activity of the enzyme is to make nonreducing transferred products via a transfer of fructosyl residue to acceptor molecules having reducing group. When nonreducing sugars, such as methyl $\alpha$-D-glucoside and methyl $\alpha$-D-galactoside, were used as an acceptor, the transfer product was also formed in spite of the reducing group blocked with methyl group. The fact that no transfer product was formed with sugar alcohols as acceptors was suggested to be due to marked conformational difference of acceptors.

• Journal of Microbiology
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• 제39권4호
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• pp.273-278
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• 2001

Shewanela, putrefaciene IR-1 and MR-1 were cultivated by using various combinations electron donor-acceptor, lactate-Fe(III) lactate-nitrate, pyruvate-FE(III), pyruvate-nitrate H$_2$ acetate-Fe(III) and H$_2$-acetate-nitrate. Both strains grew fermentatively on pyruvate and lactate but not on without and electron acceptor. In culture with Fe(III), both astrains grew on pyruvate and lactate but on H$_2$-acetate- CO$_2$. In cultivation with nitrate, both stains grew on pyruvate lactage and on H$_2$-acetate-CO$_2$ The growth yields of IR-1 pyruvate, pyruvate-Fe(III) and lactate-Fe(III) were about 3.4, 3.5, and 3.6(g cell/M substrate), respectively. From the growth properties of both strains on media with Fe(III) as an electron acceptor, the bacterial growth was confirmed not to be increased by addition of Fee(III) as an electron acceptor to the growth medium, which indicates a possibility that the dissimilatory reduction of Fe(III) to Fe(III) may not be coupled to free energy production.

• 한국추진공학회지
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• 제21권4호
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• pp.36-43
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• 2017

격벽착화기의 최적 설계를 위하여 여폭약에 의해 생성되는 충격파의 감쇄 특성과 수폭약의 민감도에 관하여 연구하였다. 충격파의 감쇄 특성은 레이저 광간섭계인 VISAR를 이용하여 측정한 격벽의 자유 표면 속도로부터 유도하였고 수폭약의 민감도는 SSGT (Small Scale Gap Test) 결과로부터 구하였다. 격벽착화기의 기폭시험을 통하여 SSGT로부터 구한 화약의 민감도가 격벽착화기와 같이 소량의 화약을 사용하는 시스템에는 충격파 지속 시간이 상이하여 적합하지 않다는 것을 밝혀내었다.

• KSBB Journal
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• 제16권2호
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• pp.200-206
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• 2001

In this study we tried to optimize the enzyme reaction conditions for the synthesis of highly branched isomaltodextrin (Mw > 2.5 kDa) using two dextransucrases from L. mesenteroides B-742CB and B-512FMCM that are dextransucrase constitutive mutants. As the concentration of sucrose or the ratio of maltose to sucrose increased, the amount of dextran decreased and the number and the amount of acceptor-products (of sucrose or maltose) increased. With high sucrose concentration (over 34%), there was more branched isomaltodextrin (as acceptor products) than dextran. When the ratio of sucrose to maltose was 2.5, there produced 86.7% of isomaltodextrin were produced. The Mw of dextrans, however, was over 2${\times}$10(sup)6 and there was no significant amounts of branched clinical dextran or high molecular weight oligosaccharides. With the combined activities of B-742CB dextransucrase and B-512FMCM dextransucrase we could synthesize high molecular weight branched isomaltodextrin (Mw>2.5 kDa). The high molecular weight dextran was composed of high branches as B-742CB dextran.

• Transactions on Electrical and Electronic Materials
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• 제2권4호
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• pp.24-29
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• 2001

GaN films were grown for various Mg doping concentrations in metal-organic chemical vapor deposition. Below the Mg concentration of 10$^{19}$ ㎤, the thermally annealed sample shows the compensated phase to n-type GaN in Hall measurement. In the MB concentration of 4$\times$10$^{19}$ ㎤ corresponding to the hole carrier concentration of 2.6$\times$1$^{19}$ ㎤ there exists a photoluminescence center of the donor and the acceptor pair transition of the 3.28-eV band. This center is correlated with the defects for a shallow donor of the $V_{Ga}$ and for an acceptor of $Mg_{Ga}$ . The acceptor level shows the binding energy of 0.2-0.25 eV, which was observed by the photon energy of the photocurrent signal of 3.02-3.31 eV. Above the Mg concentration of 4$\times$10$^{19}$ ㎤, both the Mg doping level and Mg concentration were saturated and there Is a photoluminescence center of a deep donor and an acceptor pair transition of the 2.76-eV blue band.

• 한국광학회지
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• 제2권4호
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• pp.203-208
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• 1991

모드동기된 아르곤 이온 레이저를 여기광원으로 사용한 시간상관 단일광자 계수장치를 이용하여 에틸렌글리콜 용매 내에서 Rhodamine 6G에서 Malachite Green으로의 비복사 에너지전달과정을 연구하였다. 측정된 donor의 형광소멸곡선을 full-fitting 방법으로 분석 처리하여 acceptor 농도의 변화에 따른 환산농도와 임계전이거리를 구했다. donor의 농도가 acceptor의 농도 보다 클때는 donor-donor의 원거리 쌍극자 모멘트에 의한 에너지 이주 효과를 고려해야하며 Forster 모델 보다 Huber 모델이 더 적절하였다.

• 한국전기전자재료학회논문지
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• 제35권4호
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• pp.366-371
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• 2022

Recently many efforts have been made to develop a novel class of non-fullerene electron acceptor materials for high-performance organic solar cells. In this work, anthraquinone derivatives, TMAQ and THAQ, were prepared and their availability as electron acceptor materials for organic solar cells were investigated in terms of optical, thermal, electrochemical properties, and solar cell devices. Compared to TMAQ, a significant bathochromic shift of absorption band was observed for THAQ owing to intramolecular hydrogen-bond-assisted CT interactions. Thanks to the fused aromatic ring structure and benzoquinone unit, both TMAQ and THAQ exhibited a high thermal stability and an efficient electron reduction process. In particular, the intramolecular O-H---O=C hydrogen bond of THAQ plays an important role in improving the thermal stability and electron reduction properties. In the P3HT:acceptor solar cell system, THAQ-based devices had more than ca. 6 times higher power conversion efficiency than TMAQ -based devices. These results serve as a guide for developing high-efficient anthraquinone-based electron acceptor materials.

• Journal of Photoscience
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• 제7권1호
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• pp.1-4
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• 2000

The photosensory ciliates Blepharisma japonicum and Stentor coeruleus use the hypericin-derived pigments blepharismin and stentorin, respectively, as photoreceptor chromophores. Fluorescence quenching studies have shown that the first excited singlet state of hypericin and the purified chromophores blepharismin and stentorin can be deactivated by electron transfer to an acceptor molecule with a suitable reducing potential [1,2]. This paper reports the result of a series of photobehavioral experiments performed with the aim to ascertain if the same electron accepters which quench the photoreceptor pigment fluorescence in vitro may also compete with the native acceptor molecule in its natural physiological environment. Individual cell trajectories were examined before and after light stimulation, in the presence and in the absence of potential "in vivo" electron accepters, with a microvideo-recording apparatus. Our data, on Blepharisma cells, showed that as the negative reduction potential of the electron acceptor increases, a pronounced decrease in cell photoresponsiveness was detected. A dramatic effect on cell photoresponsiveness was noticed in the presence of 1,4-benzoquinone that has the lowest negative reduction potential. Such an effect on the percentage of photoreacting cells was moderate in the case of 1,4-naphthoquinone, with a relatively higher negative reduction potential. In the presence of benzophenone, which has the highest negative reduction potential, no significant effect on photoreacting cells was noticed. Our results can support the hypothesis that in the pigment granules such a light-induced charge transfer from excited blepharismin to a suitable electron acceptor triggers sensory transduction processes in B. japonicum.

• 한국축산식품학회지
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• 제25권3호
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• pp.340-343
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• 2005

SLM을 이용한 short peptide의 분리를 목적으로 donor phase의 pH 및 acceptor phase의 염농도, membrane의 carrier 농도 차에 따른 peptide의 이동속도를 확인한 결과는 다음과 같다. 즉, pH 7.0 이하에서는 acceptor phase의 NaCl 농도나 carrier 농도에 상관없이 Gly-Tyr의 이동속도는 거의 영향을 끼치지 않았고, pH 7.0 이상에서는 이동속도가 급격히 증가함을 알 수 있었다. 그리고 Aliquat가 $8\%$ 함유된 D-SLM과 $20\%$ 함유된 H-SLM의 경우 Gly-Tyr의 이동속도는 H-SLM이 D-SLM보다 pH 9.0, 0.25 M NaCl 용액에서는 약 3배, pH 8.0, 1.0 M NaCl용액에서는 10배 정도 빠르게 이동하였다. 또한 H-SLM에서 acceptor phase의 NaCl 농도가 1.0 M 인 경우 0.25 M에 비해 10배 정도 이동속도가 빠른 것으로 나타났다. 따라서, short peptide인 Gly-Tyr의 SLM을 이용한 추출에서 donor phase의 pH 7.0 이상, carrier 농도가 높은 H-SLM 사용, acceptor phase의 염 농도가 높을수록 이동속도가 빠른 것으로 나타났다.

• 한국식품영양학회지
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• 제10권1호
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• pp.102-109
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• 1997

효소반응과 부분 산가수분해 결과를 해석하여 Leuconostoc mesenteriodes M-12 덱스트란수크라제 억셉터 반응 산물인 새로운 분지올리고당의 구조를 확인하였다. 분지올리고당 B4의 구조는 62-O-$\alpha$-D-kojibiosylmaltose인 것으로 확인되었으며, 분지올리고당 B5의 구조는 63-O-$\alpha$-D-kojibiosylpanose였다. 억셉터 반응산물을 덱스트라나제로 분해한 결과 새로운 올리고당인 D4를 확인할 수 있었다. 억셉터 반응산물을 억셉터로 이용한 두 번째 억셉터 반응의 생성물을 덱스트라나제 처리하여 D4를 얻었는데 덱스트라나제와 글\ulcorner아밀라제에 의해 분해되지 않았다. 그 구조는 62-O-$\alpha$-D-kojibiosylisomaltose로 확인되었다. 직선상 또는 분지 결합을 가진 d.p. 6 이하의 억셉터 반응산물의 생성 패턴도 확인하였다.