• Journal of Korean Vacuum Science & Technology
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• 제7권1호
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• pp.8-12
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• 2003

The effects of lattice strain on the magnetic and the transport properties of La$_{0.8}$Sr$_{0.2}$MnO$_3$films grown on a LaAlO$_3$ (001) substrate and on a La$_{0.8}$Sr$_{0.2}$MnO$_3$ layer have been studied. It was observed that the metal-insulator and the ferromagnetic transitions turn out to be at higher temperatures for the film deposited on La$_{0.8}$Sr$_{0.2}$MnO$_3$ layer with respect to that on LaAlO$_3$. The dependence of Curie temperature on the bulk and the Jahn-Teller strains has also been determined. determined.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(2)
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• pp.1189-1192
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• 2005

Due to their slow degradation properties, hydrophobic organic contaminants in estuarine sediment have been a concern for risks to human health and aquatic organisms. Studies of fate and transport of these contaminants in estuaries are further complicated by the fact that hydrodynamics and sediment transport processes in these regions are complex, involving processes with various temporal and spatial scales. In order to simulate and quantify long-term attenuation of Polycyclic Aromatic Hydrocarbons (PAH) in the Elizabeth River, VA, we develop a modeling approach, which employs the U.S. Environmental Protection Agency's water quality model, WASP, and encompasses key physical and chemical processes that govern long-term fate and transport of PAHs in the river. In this box-model configuration, freshwater inflows mix with ocean saline water and tidally averaged dispersion coefficients are obtained by calibration using measured salinity data. Sediment core field data is used to estimate the net deposition/erosion rate, treating only either the gross resuspension or deposition rate as the calibration parameter. Once calibrated, the model simulates fate and transport PAHs following the loading input to the river in 1967, nearly 4 decades ago. Sediment PAH concentrations are simulated over 1967-2022 and model results for Year 2002 are compared with field data measured at various locations of the river during that year. Sediment concentrations for Year 2012 and 2022 are also projected for various remedial actions. Since all the model parameters are based on empirical field data, model predictions should reflect responses based on the assumptions that have been governing the fate and sediment transport for the past decades.

• 한국세라믹학회지
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• 제31권6호
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• pp.651-659
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• 1994

BaTiO3 ceramics were sintered on Al2O3, MgAl2O4, MgO and Mg-, Ca-, Y-stabilized zirconia setters. Then the influence of setters on the microstructure of BaTiO3 ceramics and the stability of setters were investigated by SEM, EDAX and XRD analyses. The microstructure of BaTiO3 ceramics sintered on Al2O3, MgAl2O4, MgO and Mg-PSZ showed large grain growth, but little grain growth on Ce-TZP(Tetragonal Zirconia Policrystal). Mg-PSZ(Partially Stabilized Zirconia), Ca-PSZ, Ce-TZP setters showed extensive phase transformation. Y-TZP and fused Y-SZ (Stabilized Zirconia) setters were stable. The liquid sintering aids of BaTiO3 ceramics accelerate mass transport. The reaction of SrTiO3 in BaTiO3 with ZrO2 resulted in the formation of SrZrO3.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1560-1565
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• 2003

Thermocapillary convection in an open cylindrical annulus heated from the inside wall is investigated by two-dimensional numerical simulations. The deformable free surface is obtained as a solution of the coupled transport equations at fixed Prandtl and aspect ratio. Only steady convection can be realized in this axisymmetric computations with either non-deformable or deformable surfaces. Dynamic free-surface deformations do not induce transitions to oscillatory convection even at large Reynolds numbers. Free surfaces are convex near the cold wall due to the stagnation point, and concave near the hot wall. Free surface deformation increases with increasing Ca at a fixed Re. Two peaks appear at the free surface with low Re, while additional ripples, four peaks, occur at larger Re. Thermocapillary convection in the open annulus interior is insensitive to variations in Ca.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 하계학술연구발표회 및 한.일 공동심포지엄
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• pp.62-63
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• 2003

Electron-phonon interaction plays a significant role in forming of colossal magnetoresistance effect (CMR). Polaron formation was observed by neutron diffraction and by extended X-ray absorption fine structure (EXAFS) analysis. Local probe as given by the EXAFS is a useful method to study the polaronic charge and its dependence on temperature and ions size. Here we present the EXAFS study of polaronic charge in $La_{0.7}Ca_{0.3-x}Ba_{x}MnO_3$ compositions.

• Progress in Superconductivity
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• 제3권1호
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• pp.41-44
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• 2001

We report the current transport properties of a normal metal/organic conductor/ superconductor tunnel junction as a novel high- $T_{c}$ superconducting three terminal device. The organic copper (II) phthalocyanine (Cu-Pc) layer was used far a polaronic quasiparticle (QP) injector. The injection of polaronic QP from the Cu-Pc interlayer into a superconductor $Bi_2$$Sr_2$$CaCu_2$ $O_{8+}$ $\delta$/(BSCCO) thin film generated a substantially larger nonequilibrium effect as compared to the normal QP injection current. The tunneling spectroscopy of an Au/cu-PC/BSCCO junction exhibited a zero bias conductance peak which may be due to Andreev reflection at a Cu-Pc/d-wave superconductor junction.n..

• Applied Biological Chemistry
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• 제42권2호
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• pp.116-122
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• 1999

식물세포의 세포질 $Ca^{2+}$ 이동과 관련된 $Ca^{2+}$ 수송 특성을 조사하기 위하여, 토마토 뿌리조직으로부터 마이크로솜을 분리하고, $^{45}Ca^{2+}$ 흡수 실험을 수행하였다. 반응용액에 P-type ATPase의 선택적 저해제인 1 mM vanadate와 액포막 $H^+-ATPase$의 선택적 저해제인 50 mM $NO_3^-$를 첨가하였을 때, $^{45}Ca^{2+}$ 흡수는 각각 20%와 33%가 저해되었고, 두 가지 저해제를 동시에 첨가하였을 때, 약 47%가 저해되었다. 이러한 저해효과의 특성을 밝히기 위하여 protonophore인 gramicidin을 처리하여 막을 경계로 형성된 $H^{+}$의 농도기울기를 감소시켰을 때, $^{45}Ca^{2+}$ 흡수는 30% 가량 저해되어, 토마토 뿌리조직 마이크로솜에 $Ca^{2+}/H^+$ antiporter가 존재할 가능성을 확인하였다. Gramicidin의 저해효과는 vanadate에 의한 $^{45}Ca^{2+}$ 흡수 저해 이후에도 대조실험과 같은 정도로 얻어져 vanadate의 저해효과와는 무관한 것이 확인되었다. 그러나, $NO_3^-$를 처리하여 $^{45}Ca^{2+}$ 흡수를 저해시킨 후, gramicidin에 의한 추가저해는 거의 관측되지 않았다. 한편, 동물조직 ER/SR-type $Ca^{2+}-ATPase$의 선택적 저해제인 thapsigargin은 마이크로솜 $^{45}Ca^{2+}$ 흡수를 농도 의존적으로 저해하였으며, $10\;{\mu}M$ 농도에서 최대 저해효과를 나타냈다. Thapsigargin에 의한 저해효과는 $NO_3^-$를 사용하여 액포막 $H^{+}-ATPase$ 활성을 저해하였을 때와 gramicidin을 사용하였을 때, 현저하게 감소하였으며 , vanadate의 효과와는 무관하였다. 이러한 결과는 vanadate가 직접적으로 $Ca^{2+}-ATPase$를 저해하며, $NO_3^-$와 thapsigargin은 액포막에 위치한 $H^{+}-ATPase$의 활성을 저해하여 간접적으로 $Ca^{2+}/H^+$ antiporter를 저해함을 의미한다. 결론적으로, 본 연구의 결과는 토마토 뿌리조직에 $Ca^{2+}$ 이동을 유발하는 주요 효소로서 $Ca^{2+}-ATPase$와 액포막 $Ca^{2+}/H^+$ antiporter가 존재함을 보여준다.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1755-1762
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• 2013

A graphene-Zn/Al layered double hydroxide composite film was simultaneously prepared by electrochemical deposition on the surface of a glassy carbon electrode (G-LDH/GCE) from the mixture solution containing GO and nitrate salts of $Zn^{2+}$ and $Al^{3+}$. The modified electrode showed good electrochemical performances toward the simultaneous electrochemical detection of hydroquinone (HQ), catechol (CA) and resorcinol (RE) due to the unique properties of graphene (G) and LDH such as large active surface area, facile electronic transport and high electrocatalytic activity. The redox characteristics of G-LDH/GCE were investigated with cyclic voltammetry and differential pulse voltammetry. The well-separated oxidation peak potentials, corresponding to the oxidation of HQ, CA and RE, were observed at 0.126 V, 0.228 V and 0.620 V respectively. The amperometric response of the modified electrode exhibited that HQ can be detected without interference of CA and RE. Under the optimized conditions, the oxidation peak current of HQ is linear with the concentration of HQ from 6.0 ${\mu}M$ to 325.0 ${\mu}M$ with the detection limit of 0.077 ${\mu}M$ (S/N=3). The modified electrode was successfully applied to the direct determination of HQ in a local tap water, showing reliable recovery data.

• Progress in Superconductivity
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• 제4권2호
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• pp.99-103
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• 2003

We studied the nonequilibrium superconductivity due to tunnel injection of polaronic quasiparticle (QP) from organic photoconductor. The transport properties of an organic copper (II) phthalocyanine (Cu -Pc)/d-wave superconductor were investigated in dark and under ultraviolet (UV) radiation for performance of a novel $high -T_{c}$ superconducting three terminal device. We observed that the injection of polaronic QP from the organic Cu -Pc film into the $Bi_2$S $r_2$$CaCuO_{8+{\delta}}$ film generated a substantially larger nonequilibrium effect as compared to the normal QP injection current. We could increase the current gain by UV excitation of the organic photoconductor injector. The tunneling spectroscopy of a Cu -Pc/BSCCO junction exhibited a small enhancement of the zero bias conductance peak under the W excitation. The above phenomena are of importance in developing optically controlled three terminal superconducting device.e.

• Progress in Superconductivity
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• 제3권2호
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• pp.140-145
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• 2002

An enhancement of the c-axis differential conductance around the zero-bias voltage near the superconducting transition temperature $T_{c}$ has been observed in $Au/Bi_2$$Sr_2$$CaCu_2$$O_{8+x}$ junctions. We attribute such an enhancement to the Andreev reflection (AR) between the surface Cu-O bilayer with suppressed superconductivity and the next superconducting Cu-O bilayer. The continuous evolution of the differential conductance, from gap like depression to an AR-like peak structure, around the zero-bias voltage points to weakening of the barrier strength of the nonsuperconducting layer between adjacent Cu-O bilayers as temperature approaches $T_{c}$ from below. The peak structure disappeared just below the bulk $T_{c}$ value of underdoped Bi2212 single crystals, whereas it survived up to ~1 K above $T_{c}$ in Junctions prepared on slightly overdosed crystals. According to a recently proposed theoretical consideration, a wider temperature range of the AR a bone $T_{c}$ is expected in the underdoped regime when phase-incoherent preformed pairs emerge in the pseudogap state. Our result is in contradiction to the preformed pair scenario. scenario.o.