Isolation and partial characterization of a bacteriocin produced by <i>Pediococcus pentosaceus</i> K23-2 isolated from Kimchi

Shin, M.S.,Han, S.K.,Ryu, J.S.,Kim, K.S.,Lee, W.K. Blackwell Publishing Ltd 2008 Journal of Applied Microbiology Vol.105 No.2

<P>Abstract</P><P>Aims: </P><P>Screening and partial characterization of a bacteriocin produced by <I>Pediococcus pentosaceus</I> K23-2 isolated from Kimchi, a traditional Korean fermented vegetable.</P><P>Methods and Results: </P><P>A total of 1000 lactic acid bacteria were isolated from various Kimchi samples and screened for the production of bacteriocin. Pediocin K23-2, a bacteriocin produced by the <I>Pediococcus pentosaceus</I> K23-2 strain, showed strong inhibitory activity against <I>Listeria monocytogenes</I>. The bacteriocin activity remained unchanged after 15 min of heat treatment at 121°C or exposure to organic solvents; however, it diminished after treatment with proteolytic enzymes. The bacteriocin was maximally produced at 37°C, when the pH of the culture broth was maintained at 5·0 during the fermentation, although the optimum pH for growth was 7·0. The molecular weight of the bacteriocin was about 5 kDa according to a tricine SDS-PAGE analysis.</P><P>Conclusions: </P><P><I>Pediococcus pentosaceus</I> K23-2 isolated from Kimchi produces a bacteriocin, which shares similar characteristics to the Class IIa bacteriocins. The bacteriocin is heat stable and shows wide antimicrobial activity against Gram-positive bacteria, especially <I>L. monocytogenes</I>.</P><P>Significance and Impact of the Study: </P><P>Pediocin K23-2 and pediocin K23-2-producing <I>P. pentosaceus</I> K23-2 could potentially be used in the food and feed industries as natural biopreservatives, and for probiotic application to humans or livestock.</P>

희토류 금속을 첨가한 적철광의 자기상 전이

한경훈,신경호,김정기,정재윤 漢陽大學校 自然科學硏究所 2000 自然科學論文集 Vol.19 No.-

다결정시료(Fe₂O₃)1-x(Eu₂O₃)x (x=0.04와 0.06)계의 자기상 전이를 연구하기 위해 상온에서의 X선 회절, 액체질소온도에서 상온에 이르는 온도구간에서의 Mossbauer 분광과 약 8K에서 300K의 온도구간에서의 자기능률 측정방법을 사용하였다. X선 회절은 본 연구의 다결정시료가 a-Fe₂O₃와 동일한 rhombohedral결정구조를 가짐을 보인다. X선 회절선의 결과를 이용하여 비선형최소자승법을 써서 각 시료의 격자상수값을 구하였다. Mossbauer 분광결과는 자기상 전이가 255K<T<265K 온도 영역에서 일어남을 보인다. 온도영역 T<255K에서의 초미세 자기장의 온도 의존성에 반강자성 spinwave이론이 잘 적용됨을 보인다. 온도에 따른 magnetization의 변화로 자기상전이 온도를 관찰하였으며, 이 결과는 Mossbauer 분광 결과와 잘 일치 하였다. 상온에서의 hysteresis 곡선은 Eu농도가 증가함에 따라서 보자력이 증가하지만 자화와 잔류자화는 감소했음을 알 수 있었다. A study of magnetic transition for the polycrystalline (Fe₂O₃)1-x(Eu₂O₃)x (x=0.04 and 0.06) has been performed by the methods of X-ray diffraction at room temperature, Mossbauer spectroscopy within the temperature range from liquid nitrogen to room temperature, and a measurement of magnetic moment within temperature range of 8K∼300K. X-ray diffraction shows that the samples are in the same rhombohedral crystal structure as that of a-Fe₂O₃. The lattice parameter of the samples has been determined from X-ray diffraction patterns using computer with a progam of nonlinear square-fit. The Mossbauer results tell us that the magnetic transition of the samples occurs in the temperature region of 255K<T<265K. The temperature dependence of magnetic hyperfine field of the samples is in good agreement with a spin-wave theory for a antiferromagnetic phase within the temperature range from liquid nitrogen to 255K. The magnetic phase transition was observed by a temperature dependence of magnetization and the result was in good agreement with that of Mossbauer. Magnetic hysteresis curves indicated that the values of coercivity increase but that of magnetization and remanence of the samples decrease as increasing the concentration of Eu.

CBD 방법에 의한 CdS 박막의 성장과 광전도 특성

황광준,이상열,유상하,서상석,문종대,신영진,정태수,신현길,김택성,송정훈,유기수 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.16 No.-

Chemical bath deposition 방법으로 다결정 CdS 박막을 세라믹 기판 위에 성장시킨 다음 온도를 변화시켜 열처리하고 X-선 회절무늬를 측정하여 결정구조를 밝혔다. 550℃로 열처리한 시료의 경우 X-선 회절무늬로 부터 외삽법에 의해 a_。와 c_。는 각각 4.1364 Å과 6.7129 Å인 육방정계임을 알았다. 이 때 낱알크기는 약 0.35㎛이었다. Van der Pauw 방법으로 Hall 효과를 측정하여 운반자 농도와 이동도의 온도의존성을 연구하였다. 이동도는 33 K 에서 150 K 까지는 압전산란에 의하여, 150 K 에서 293 K 까지는 극성광학산란에 의하여 감소하는 경향이 나타냈다. 광전도 셀의 특성으로 스텍트럼 응답, 감도(γ), 최대허용소비전력 및 응답 시간을 측정하였다. Polycrystalline CdS thin films were grown on creamic substrate using a chemical bath deposition method. They were annealed at various temperature and X-ray diffraction patterns were measured by X-ray diffractometer in order to study CdS polycrystal structure. Using extrapolation method of X-ray diffraction patterns for the CdS samples annealed in N_2 gas at 550℃ it was found hexagonal structure whose lattice constants a_o and c_o were 4.1364 Å and 6.7120Å, respectively. Its grain size was about 0.35 ㎛. Hall effect on this sample was measured by Van der Pauw method and studied on carrier density and mobility depending on temperature. From Hall data, the mobility was likely to be decreased by piezo electric scattering at temperature range of 33K and 150K and by polar optical scattering at temperature range of 150K and 293K. We measured also spectral response, sensitivity (γ), maximum allowable power dissipation and response time on these samples.

Chemical Bath Deposition 방법으로 제작한 CdSe 박막의 특성

홍광준,이상열,유상하,서상석,문종대,신영진,정태수,신현길,김택성,송정훈,유기수 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.16 No.-

Chemical bath deposition 방법으로 다결정 CdSe 박막을 세라믹 기판 위에 성장시킨 다음 온도를 변화시켜 열처리하고 X-선 회절무늬를 측정하여 결정구조를 밝혔다. 450℃로 열처리한 시료가 X-선 회절무늬로 부터 외삽법에 의해 a_o와 c_o 는 각각 4.302 Å과 7.014 Å인 육방정계임을 알았다. 이 때 낱알크기는 약 0.3㎛이었다. Van der Pauw 방법으로 Hall 효과를 측정하여 운반자 농도와 이동도의 온도의존성을 연구하였다. 이동도는 33 K 에서 200 K 까지는 압전산란에 의하여, 200 k 에서 293 K 까지는 극성광학산란에 의하여 감소하는 경향이 나타냈다. 광전도 셀의 특성으로 스텍트럼 응답, 감도(γ), 최대허용소비전력 및 응답 시간을 측정하였다. Polycrystalline CdSe thin films were grown on creamic substrate using a chemical bath deposition (CBD) method. They were annealed at various temperature and X-ray diffraction patterns were measured by X-ray diffractometer in order to study CdSe polycrystal structure. Using extrapolation method of X-ray diffraction patterns for the CdSe samples annealed in N_2 gas at 450℃ it was found hexagonal structure whose lattice parameters a_o and c_o were 4.302 Å and 7.014 Å, respectively. It grain size was about 0.3 ㎛. Hall effect on this sample was measured by Van der Pauw method and studied on carrier density and mobility depending on temperature. From Hall data, the mobility was likely to be decreased by piezo electric scattering at temperature range of 33 K and 200 K, and by polar optical potical scattering at temperature range of 200 K and 293 K. We measured also spectral response, sensitivily (γ), maximum allowable power dissipation and response time on these samples.

광전도체의 CdS 단결정 성장과 물리적 특성

정태수,유평열,신영진,신현길,김택성,정철훈,이훈,신영신,홍광준,유기수 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.16 No.-

승화방법으로 광전도체의 CdS 단결정을 성장하였고 외삽법으로 구한 a_o와 c_o 의 격자상수 값은 각각 4.1318Å과 6.7122Å임을 알았다. Hall 측정값으로 부터 상온에서의 CdS 단결정의 운반자 농도와 이동도는 각각∼10^23m^-3과 2.93×10 exp (-2)㎡/V sec 이였으며 온도에 따른 이동도 변화는 33 K에서 150 K까지는 T^1/2 에 따라 증가하는 경향이 있고 180 K 에서 상온까지는 T^-2에 따라 감소한 경향이 나타났다. 광전류 측정으로 부터 나타난 단파장대의 봉우리는 진성전이에 기인하는 봉우리였으며 이 봉우리의 에너지값은 CdS 광전도체에 에너지 밴드 갭과 동일한 값을 나타냄을 알았다. A CdS single crystal was grown by using sublimation method. Lattice constants, a_o and c_o , obtained by using extrapolation were 4.1318 Å and 6.7122 Å, respectively. The carrier density was∼10^23m^-3 and the mobility was 2.93×10 exp (-2)㎡/V-sec from measured Hall data at room temperature. The mobility has a increasing tendency in proportion to T^1/2 from 33 K to 150 K and a decreasing tendency in proportion to T^-2 from 180 K to room temperature. The short wavelength band peak measured from photocurrent was due to intrinsic transition, and the energy value of this peak was equal to the energy band gap of CdS photoconductor.

Induction of Cell Death in Human Macrophages by a Highly Virulent Korean Isolate of <i>Mycobacterium tuberculosis</i> and the Virulent Strain H37Rv

Sohn, H.,Lee, K.-S.,Kim, S.-Y.,Shin, D.-M.,Shin, S.-J.,Jo, E.-K.,Park, J.-K.,Kim, H.-J. Blackwell Publishing Ltd 2009 Scandinavian journal of immunology Vol.69 No.1

<P>Abstract</P><P>Recent studies have suggested that virulent strains of <I>Mycobacterium tuberculosis</I> induce apoptosis in macrophages less often than do attenuated strains. K-strain, which belongs to the Beijing family, is the most frequently isolated clinical strain of <I>M. tuberculosis</I> in Korea. In this study, we investigated the differential induction of cell death in human monocytic THP-1 cells by K-strain and H37Rv, a virulent but laboratory-adapted strain of <I>M. tuberculosis</I>. Although no significant difference in growth rate was observed between the cells exposed to K-strain and those exposed to H37Rv, the levels of protective cytokines such as tumour necrosis factor (TNF)-&agr;, interleukin (IL)-6 and IL-12p40 were lower in K-strain-infected cells than in H37Rv-infected cells. Cell viability assays showed that both K-strain and H37Rv, but not heat- or streptomycin-killed bacteria, induced THP-1 cell death in a TNF-independent manner. In contrast, double staining with fluorochrome-labelled inhibitors of caspase and propidium iodide and lactate dehydrogenase release assays revealed that K-strain induced significantly higher levels of necrotic cell death, rather than apoptosis, in THP-1 cells than did H37Rv. Anti-apoptotic <I>Bcl-2</I>, <I>Mcl-1</I>, <I>Bfl-1</I> and <I>Bcl-xL</I> in the cells were significantly upregulated following infection with K-strain compared with H37Rv, whereas <I>Bax</I> was slightly upregulated in response to infection with both H37Rv and K-strain. These results suggest that the highly virulent K-strain keeps cellular apoptosis as a host defense mechanism to a minimum and induces necrosis in macrophages.</P>

Abnormal Temperature Dependence of Tunneling Magnetoresistance for Magnetic Tunnel Junctions

K. I. Lee,J. H. Lee,W. Y. Lee,K. Rhie,B. C. Lee,K.-H. Shin 한국자기학회 2002 Journal of Magnetics Vol.7 No.2

Magnetic tunnel junctions (MTJs) were fabricated with high bias for plasma oxidation and the effects of annealing on the temperature dependence of tunneling magnetoresistance (TMR) were investigated experimentally. As-grown, TMR increases, peaks around 160 K, and decreases with increasing temperature from 80 K to 300 K. When MTJs are annealed, Tmax, the temperature at which maximum TMR is obtained, decreases as annealing temperature increases to the optimal point. In order to explain this abnormal temperature dependence of TMR, the difference of conductance between parallel and antiparallel alignments of magnetizations as a function of temperature is also analyzed. The shifts of Tmax due to annealing process are described phenomenologically with spin-dependent transfer rates of electrons tunnel through the barrier.

Alkali Borate 유리에 있어서 있어서 철이온의 Mo¨ssbauer 效果에 關한 硏究

申榮男,朴冠鎬,洪致裕 동국대학교 재료과학연구소 1982 材料科學硏究所 論文集 Vol.2 No.-

酸化鐵을 넣은 Alkali Borate 非晶質 유리를 만들어 Mo¨ssbauer Spectrum으로 Mo¨ssbauer parameters와 철 ion의 狀態에 대해서 硏究되었다. 試料의 成分은 X% A, (100-X)% B_2O_3, 4% Fe_2O_3로 하여 A는 K_2O, Na_2O, 및 K_2O이고, X=10,20 및 30을 취했다. 이 混合物을 잘 섞어 電氣爐에서 900℃ 溫度로 約 2時間동안 용융시켰다. I.S.와 Q.S.는 X가 增加함에 따라 減少함을 보였고, Li-Na-K의 原子半經에 따라 I.S.는 增加함을 보이나 Q.S.는 감소함을 보였다. 線幅은 X가 增加함에 따라, Li-Na-K 順序로 減少함을 보였다. Amorphous alkali borate glasses were prepared to contain 4 mole% of ferric oxide as impurity. Mo¨ssbauer parameters and the state of iron in alkali borate glasses were studied by Mo¨ssbauer spectra. X% A_2O, (100-X)% B_2O_3, 4% Fe_2O_3, where A=Li, Na or K and X=10, 20 or 30 are composed, were prepared. Mixtures were melted in air in furnace at 900℃ for two hours. Isomer shift and quadrupole splitting were decreased according to increasing of X component, and according to increasing of X component. Isomer shift was increased but quadrupole splitting was decreased. And the line width was decreased according to increasing of X component and Li-Na-K series.

Evidence of a low-temperature dipolar glass state in polycrystalline (NH4)3H(SO4)2

Shin H. K. 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.83 No.11

Detailed dielectric measurements are reported for polycrystalline (NH4)3H(SO4)2 at temperatures 10 K <T < 100 K and frequencies 20 Hz <ν < 3 MHz. Instead of the ferroelectric phase transition expected at 63 K, a typical dipole glass transition was observed at around 60 K. The frequency dependence of the complex dielectric permeability at T < 50 K was well described by a sum of two Cole-Cole functions. One of the two relaxators provides a background contribution to the dielectric dispersion. The most probable relaxation time for the main relaxator was best fitted to the modified Arrhenius law with τ0=3.5 ×10-13 s, E =50 Kγ, and γ =0.37.

Chemical Bath Deposition 방법으로 제작한 CdSe 박마의 특성

신영진,홍광준,이상열,유상하,서상석,문종대,신현길,김택성,송정훈,유기수,정태수 한국센서학회 1993 센서학회지 Vol.2 No.1

Polycrystalline CdSe thin films were grown on ceramic substrate using a chemical bath deposition (CBD) method. They were annealed at various temperature and X-ray diffraction patterns were measured by X-ray diffractometer in order to study CdSe polycrystal structure. Using extrapolation method of X-ray diffraction patterns for the CdSe samples annealed in N₂ gas at 450℃ it was found hexagonal structure whose lattice parameters a_o and c_o were 4.302 A and 7.014 A, respectively. Its grain size was about 0.3 ㎛. Hall effect on this sample was measured by Van der Pauw method and studied on carrier density and mobility depending on temperature. From Hall data, the mobility was likely to be decreased by piezo electric scattering at temperature range of 33 K and 200 K, and by polar optical scattering at temperature range of 200 K and 293 K. We measured also spectral response, sensitivity (γ), maximum allowable power dissipation and response time on these samples.