• Plant Biotechnology Reports
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• 제5권4호
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• pp.309-315
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• 2011

Rice grown in anaerobic waterlogged soil accumulates ammonium as a major source of nitrogen (N). We have compared the physiological symptoms of rice seedlings subjected to N-starvation stress with those receiving sufficient N, based on measurements of shoot/root length and weight and an analysis of protein expression patterns. N starvation marginally increased root growth but notably decreased shoot biomass. N uptake was reduced by >50% in the roots and shoots of N-starved seedlings. To better understand the mechanism of N starvation in rice, we performed a comparative proteome analysis of proteins isolated from rice leaves. Twenty-five differentially expressed proteins were analyzed by matrixassisted laser desorption/ionization time-of-flight (TOF) mass spectrometry and electron spray ionization quadrupole TOF. Functional analysis of the N-starvation response proteins suggested their involvement in protein synthesis and fate, metabolism, and defense. These results indicate that these proteins may play important roles in regulating the plant's complex adaptation responses for N use during N starvation. The proteins may be useful for further characterization of protein function in plant N nutrition.

• 대한화학회지
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• 제59권5호
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• pp.373-378
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• 2015

Di-n-butyl phosphorochloridate((CH₃CH₂CH₂CH₂O)₂POCl, 1)의 가용매 분해반응의 속도상수를 여러 가지 용매 중에서 구하였다. 반응용매 28개의 속도상수를 이용하여 확장된 Grunwald-Winstein 식에 의하여 구한 용매의 친핵성도와 이온화력에 대한 기질의 민감도(l = 1.40, m = 0.42)는 S_N2 반응임을 예상할 수 있다. 이를 뒷받침할 수 있는 추가 요소들은 상대적으로 작은 양의 값의 ΔH^≠ (8.0 ~ 15.9 kcal·mol⁻¹)와 큰 음의 값의 ΔS^≠(−25.8~−53.1 cal·mol⁻¹·K⁻¹), Kivinen의 n 값(0.9~1.7) 그리고 용매동위원소효과 값(1.69)이다.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3795-3799
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• 2013

The second-order rate constants ($k_N$) have been measured spectrophotometrically for nucleophilic substitution reactions of Y-substituted-phenyl 2-methylbenzoates (6a-e) with a series of cyclic secondary amines in MeCN at $25.0{\pm}0.1^{\circ}C$. Comparison of the $k_N$ values for the reactions of 4-nitrophenyl 2-methylbenzoate (6d) with those reported previously for the corresponding reactions of 4-nitrophenyl 2-methoxybenzoate (5) reveals that 6d is significantly less reactive than 5, indicating that modification of 2-MeO in the benzoyl moiety of 5 by 2-Me (i.e., $5{\rightarrow}6d$) causes a significant decrease in reactivity. This supports our previous report that aminolysis of 5 proceeds through a six-membered cyclic intermediate, which is highly stabilized through intramolecular H-bonding interactions. The Br${\o}$nsted-type plot for the reactions of 6d with a series of cyclic secondary amines is linear with ${\beta}_{nuc}=0.71$, which appears to be a lower limit of ${\beta}_{nuc}$ for a stepwise mechanism with breakdown of an intermediate ($T^{\pm}$) being rate-determining step (RDS). The Br${\o}$nsted-type plot for the reactions of 6a-e with piperidine is curved, i.e., the slope of Br${\o}$nsted-type plot (${\beta}_{lg}$) decreases from -1.05 to -0.41 as the leaving-group basicity decreases. The nonlinear Br${\o}$nsted-type plot has been taken as evidence for a stepwise mechanism with a change in RDS (e.g., from the $k_2$ step to the $k_1$ process as the leaving-group basicity decreases). Dissection of $k_N$ into the microscopic rate constants associated with the reactions of 6a-e with piperidine (e.g., $k_1$ and $k_2/k_{-1}$ ratio) also supports the proposed mechanism.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1993년도 제4회 학술발표회 논문개요집
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• pp.63-64
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• 1993

• Journal of Astronomy and Space Sciences
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• 제35권1호
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• pp.7-18
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• 2018

We have investigated the intensities and full width at half maximum (FWHM) of the high dispersion spectroscopic N III emission lines of AG Peg, observed with the Hamilton Echelle Spectrograph (HES) in three different epochs at Mt. Hamilton's Lick Observatory. The earlier theoretical Bowen line study assumed the continuum fluorescence effect, presenting a large discrepancy with the present data. Hence, we analyzed the observed N III lines assuming line fluorescence as the only suitable source: (1) The O III and N III resonance line profiles near ${\lambda}$ 374 were decomposed, using the Gaussian function, and the contributions from various O III line components were determined. (2) Based on the theoretical resonant N III intensities, the expected N III Bowen intensities were obtained to fit the observed values. Our study shows that the incoming line photon number ratio must be considered to balance at each N III Bowen line level in the ultraviolet radiation according to the observed lines in the optical zone. We also found that the average FWHM of the N III Bowen lines was about $5km{\cdot}s^{-1}$ greater than that of the O III Bowen lines, perhaps due to the inherently different kinematic characteristics of their emission zones.

• 대한화학회지
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• 제18권1호
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• pp.8-11
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• 1974

물함량 50% 이하의 아세토니트릴-물 혼합용매내에서의 염화벤젠술포닐의 $p-H, p-NO_2, p-Br, p-OCH_3$, 치환체들의 가용매분해를 반응속도론적으로 연구한 결과 Hammett 도시는 concave한 곡선들이나 $S-N2$성격이 압도적이었으며 물은 친핵제 뿐만 아니라 general base로도 작용하고 있음을 알았다.

• 대한화학회지
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• 제37권8호
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• pp.695-701
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• 1993

25$^{\circ}C$에서 메탄올, 에탄올, 아세톤 이성분 혼합수용액과 물, 메탄올에서의 가용매분해반응 속도 상수를 결정하고, 이들 속도자료를 Grunwald-Winstein 식과 Kivinen 관계식을 이용하여 해석하였다. 또한 물과 메탄올에서의 속도론적 용매 동위원소 효과와 알코올-물 혼합용매계에서 생성물 선택성 값을 결정하였다. 염화 2-티오펜술포닐의 가용매 분해반으에 대한 속도론적 용매 동위원소 효과는 메탄올과 물에서 각가 2.24와 1.47이었다. 에탄올-물에서의 술포닐 에스테르 형성에 대한 선택성 값은 최대값을 나타내었다. 메탄올과 물에서의 속도론적 용매 동위원소 효과, 알코올 수용액에서의 선택성 자료와 용매효과로부터, 본 연구에서의 반응은 극성이 낮은 용매계에서는 일반염기 촉매반응과 또는 S$_A$N 반응이 유리하고, 극성이 큰 용매계에서는 S$_N$2 반응의 유리한 반응으로 진행되는 것으로 제안하였다.

• Biomolecules & Therapeutics
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• 제17권4호
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• pp.379-387
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• 2009

We have previously reported that N-ethylmaleimide (NEM) induces apoptosis through activation of $K^+$, $Cl^-$-cotransport (KCC) in HepG2 human hepatoblastoma cells. In this study we investigated the possible role of phospholipase $A_2$ ($PLA_2$)-arachidonic acid (AA) signals in the mechanism of the NEM-induced apoptosis. In these experiments we used arachidonyl trifluoromethylketone ($AACOCF_3$), bromoenol lactone (BEL) and p-bromophenacyl bromide (BPB) as inhibitors of the calcium-dependent cytosolic $PLA_2$ ($cPLA_2$), the calcium-independent $PLA_2$ ($iPLA_2$) and the secretory $PLA_2$ ($sPLA_2$), respectively. BEL significantly inhibited the NEM-induced apoptosis, whereas $AACOCF_3$ and BPB did not. NEM increased AA liberation in a dose-dependent manner, which was markedly prevented only by BEL. In addition AA by itself induced $K^+$ efflux, a hallmark of KCC activation, which was comparable to that of NEM. The NEM-induced apoptosis was not significantly altered by treatment with indomethacin (Indo) and nordihydroguaiaretic acid (NDGA), selective inhibitors of cyclooxygenase (COX) and lipoxygenase (LOX), respectively. Treatment with AA or 5,8,11,14-eicosatetraynoic acid (ETYA), a non-metabolizable analogue of AA, significantly induced apoptosis. Collectively, these results suggest that AA liberated through activation of $iPLA_2$ may mediate the NEMinduced apoptosis in HepG2 cells.

• 한국응용곤충학회지
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• 제17권1호
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• pp.15-22
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• 1978

1. "Kresek" 유발균주(K균주)는 품종에 따라서 발현에 차이가 있었으며 지상부 또는 지하부에 접종하여도 "Kresek"을 유발시킬 수 있었으나 대조균주(N균주)는 전연 유발되지 않았다. 2. 엽백의 도관직경은 밀양 23이 유신이나 통일보다 현저히 작았으며 이들간에 고도의 통계적인 유의차가 인정되었다. 3. 밀양 23의 즙액에서 K균주들은 N균주들보다 세균의 증식이 왕성하였으며 통일에서는 균주들간에 증식의 차이가 없었다. 4. 밀양 23의 즙액친서는 K균주의 Dead phase가 정종 9일째부터 N균주는 4일째부터 시작되었으며 통일에서는 모두 3일째부터 시작되었다. 5. 밀양 23즙액의 경우 pH 3.0-4.0 범위에서 다량의 침전물이 형성되었으나 동일의 증액에서는 극히 소량의 침전물을 관찰할 수가 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1114-1116
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• 1995

P/N(CuO/ZnO) Heterojunction gas sensors were made by 2-step sintering methods and its gas sensing property was measured by varying the injected gases and the operating temperatures. As the applied voltage was increased in air ambients, the current-voltage characteristics shown the ohmic properties. However, when the CO gas ambients, 500 ppm at $200^{\circ}C$, the current-voltage characteristics behaves like a rectifying diode s after 3 mins later and its conduction mechanism is discussed qualitatively for the first times.