• 제목/요약/키워드: levan

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APPLICATIONS OF HILBERT SPACE DISSIPATIVE NORM

  • Kubrusly, Carlos S.;Levan, Nhan
    • 대한수학회보
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    • 제49권1호
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    • pp.99-107
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    • 2012
  • The concept of Hilbert space dissipative norm was introduced in [8] to obtain necessary and sufficient conditions for exponential stability of contraction semigroups. In the present paper we show that the same concept can also be used to derive further properties of contraction semigroups, as well as to characterize strongly stable semigroups that are not exponentially stable.

BIISOMETRIC OPERATORS AND BIORTHOGONAL SEQUENCES

  • Kubrusly, Carlos;Levan, Nhan
    • 대한수학회보
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    • 제56권3호
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    • pp.585-596
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    • 2019
  • It is shown that a pair of Hilbert space operators V and W such that $V^*W=I$ (called a biisometric pair) shares some common properties with unilateral shifts when orthonormal bases are replaced with biorthogonal sequences, and it is also shown how such a pair of biisometric operators yields a pair of biorthogonal sequences which are shifted by them. These are applied to a class of Laguerre operators on $L^2[0,{\infty})$.

Pseudomonas sp.가 생산하는 Inulinase에 관한 연구 -효소의 정제와 성질 - (Purification and Properties of Extracellular Inulinase of Pseudomouas sp.)

  • 이태경;최용진;양한철
    • 한국미생물·생명공학회지
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    • 제16권4호
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    • pp.259-264
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    • 1988
  • Pseudomonas sp.로 동정된 토양분리균의 inulinase를 ammonium sulfate 분획, DEAE Sephadex A-50 Chromatography, Sephadex G 100 및 Sephadex G200 gel여과 등의 과정을 거쳐 정제 한 결과 inulinase PI과 PII의 두 isoenzyme으로 분리되었으며 각각 약 24배와 17배 정제되어 단일단백질로 분리되었다. PI, PII 두 isoenzyme은 다같이 sucrose, raffinose 및 levan은 분해하지 못하고 inulin만을 endo-type로 분해 절단하는 $\beta$-2,1-fructanfructano hydrolase(EC 3.2.1.7)임이 밝혀졌다. 효소활성 최적온도는 두 효소가 같은데 비해 (55$^{\circ}C$), 최적 pH는 PI이 pH5.5, PII가 pH6.0으로 약간의 차이를 보였다. Inulin에 대한 Km값은 PI ; 2$\times$$10^{-3}$M, PII : 5$\times$$10^{-3}$M로써 PI효소가 PII보다 약간 높은 친화력을 보였다.

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서목태의 식물성 에스트로겐과 프럭토즈폴리머 레반의 보충에 의한 폐경 후 여성의 골질환 개선 효과

  • 강순아;김승현;장기효;장병일;임융호
    • 대한지역사회영양학회:학술대회논문집
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    • 대한지역사회영양학회 2004년도 춘계학술대회
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    • pp.436-437
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    • 2004
  • 폐경기성 골다공증의 치료 방법인 에스트로겐 투여에 의한 위험성을 보완하기 위해 한약재 및 식품 등 천연물의 활성성분을 이용한 대체 요법에 대한 연구가 진행되면서, 이소플라본(isoflavone)계 식물성 에스트로겐을 함유한 기능성식품의 개발이 진행되고 있다. 특히 콩과식물 중 isoflavone 함량뿐 아니라 배당체와 결합되지 않은 aglycone 함량이 높은 서목태(쥐눈이콩; 약콩)와 무기질 홉수 중진 효과를 지닌 프럭토즈폴리머(levan; beta-2,6 linked fructose polymer, ∼6,000,000 Da)를 폐경 후 여성들에게 공급하여 골형성 지표와 골흡수 지표의 변화, 혈중 칼슘 농도, 골대사를 살펴보고 골밀도의 변화를 살펴봄으로써 골다공증 예방제로서의 기능성물질의 효능을 살펴보고 신물질의 개발에 기여하고자 하였다.(중략)

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PARANORMAL CONTRACTIONS AND INVARIANT SUBSPACES

  • Duggal, B.P.;Kubrusly, C.S.;Levan, N.
    • 대한수학회지
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    • 제40권6호
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    • pp.933-942
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    • 2003
  • It is shown that if a paranormal contraction T has no nontrivial invariant subspace, then it is a proper contraction. Moreover, the nonnegative operator Q = T/sup 2*/T/sup 2/ - 2T/sup */T + I also is a proper contraction. If a quasihyponormal contraction has no nontrivial invariant subspace then, in addition, its defect operator D is a proper contraction and its itself-commutator is a trace-class strict contraction. Furthermore, if one of Q or D is compact, then so is the other, and Q and D are strict ontraction.

Isolation and Characterization of Bacillus sp. KD1014 Producing Carboxymethyl-Cellulase (Isolation and characterization of Bacillus sp. KD1014 producing carboxymethyl-cellulase)

  • Lee, Kyung Dong;Kim, Jong Ho;Kim Hoon
    • Journal of Microbiology
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    • 제34권4호
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    • pp.305-310
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    • 1996
  • A microorganism producing carboxymethyl-cellulase (CMCase) was isolated from 300 soil and compost samples. The isolate was identified as Bacillus sp. by $Biolog^{TM}$ test and fatty acid analysis, and named as Bacillus sp. KD1014. The isolate could degrade, in addition to CMC, various kinds of polysaccharides such as levan, xylan, starch, and filter paper but hardly degrade microcrystalline Avicel. The optimum growth and CMCase production of the isolate was observed between 16-and 25 hr-culture at 45$^{\circ}C$ and pH 5.0. The maximum CMCase activity was observed at pH 4.5 and 6$0^{\circ}C$. The CMCase was found to bind to Avicel. The CMCase was internally cleaved as growth continued. When crude supernatant was used for activity staining, three major bands were detected on a native gel, however, only one major band was detected on a denaturating gel after removal of the detergent.

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Purification and characterization of glucosyltransferase and fructosyltransferase from Leuconostoc mesenteroides NRRL B-1149

  • 박준성;박현정;이소영;김도원;김도만
    • 한국생물공학회:학술대회논문집
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    • 한국생물공학회 2002년도 생물공학의 동향 (X)
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    • pp.188-191
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    • 2002
  • A glucan and a fructan producing enzymes from Leuconostoc mesenteroides NRRL B-1149 were prepared and concentrated from the cu1ture of 1.5% sucrose using polysulfone ultrafiltration hollow fiber in the presence of 0.1% (w/v) Tween 80, 1 mM $CaCl_2$, and 0.02% $NaN_3$. The molecular masses of the enzymes were estimated to be about 213.6 kDa and 180 kDa, respectively, based on the PAS staining for the glucosyltransferase and Mukasa method for fructosyltransferase. Polymers produced by the enzymes showed different solubility; an insoluble glucan and a soluble fructan. The linkages of polymers were determined by methylation using Hakomori reagent and following acid hydrolysis. The glucan was composed of ${\alpha}$-1,6 and 1,3 linkages and the fructan showed similar linkage data of levan.

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