• 한국전자파학회논문지
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• 제12권6호
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• pp.1009-1017
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• 2001

우주전파의 신호를 관측하기 위한 1 GHz대역의 음향광학 전파분광기를 설계.제작하였다. 이 전파분광기는 다중채널 방식의 신호의 세기가 미약한 우주 전파신호를 분석하기 위한 초고감도의 전파 분광기로, 관측되는 스펙트럼의 모양을 상세히 측정할 수 있는 전파분광기이다. 주파수 분해능과 광대역 주파수 성분을 포함하는 이 음향광학 전파분광기의 광원(optical source)으로는 He-Ne 레이저를 사용하였고, 1 GHz에서 2 GHz까지의 대역폭을 갖는 광대역 GaP 광펼향 소자를 사용하였으며, 광신호 검출을 위해 2,048 채널의 CCD를 사용하였다. 전파망원경을 통해 우주전파신호인 CRL 2688, IRC 10216 그리고 NGC 5005 은하 중심의 12CO(J= 1 ~0) 분자선(molecular line)을 관측한 결과, 광대역의 특성을 가지며 주파수 분해능이 양호함을 확인하였다.

• 상하수도학회지
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• 제32권3호
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• pp.279-289
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• 2018

N-nitrosodimethylamine (NDMA) is a class of disinfection byproducts and a frequently detected nitrosamine with carcinogenic potentials. This review summarizes NDMA precursors, their formation mechanisms in chloraminated water, and mitigation strategies. Understanding the formation mechanism and characteristics of precursors is essential for developing a mitigation strategy. Dimethylamine (DMA), the most widely studied NDMA precursor, has an NDMA molar yield up to 3%. In comparison, a subset of tertiary amines, e.g., pharmaceuticals, generate up to 90% upon chloramination. Potent NDMA precursors, are characterized by their negative partial charge, low planarity values and molecular weight, and high bond length and $pK_a$ values. A nucleophilic substitution of tertiary amine on chloramine is a key reason for the high NDMA yield from the most potent NDMA precursors. The distribution and fate of NDMA in surface water, aquifers, and its formation in the distribution system can be mitigated through two strategies: (1) degrading or/removing NDMA after its formation and (2) pre-treatment of its precursor's prior chloramination.

• 한국전기전자재료학회논문지
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• 제27권11호
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• pp.718-724
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• 2014

In this work, in order to manufacture the photoelectrode of dye-sensitized solar cells, the different anatase $TiO_2$ paste was prepared by simple route using hydrothermal method. In comparison with the traditional preparing process, the hydrothermally synthesized $TiO_2$ gel was used to make paste directly. Thus, the making process was simplified and the solar conversion efficiency was improved. In comparison with 5.34% solar energy efficiency of HP-1 photoelectrode, the 6.23% efficiency of HDP-1 electrode was improved by 16.67%. This is because hydrothermally synthesized $TiO_2$ gel was used to make paste directly, the dispersibility between $TiO_2$ particles was improved and get the smoother network, leading to the charge transport ability of the electron generated in dye molecular was improved. Further, HDP-2 photoelectrode delivered the best results with Voc (open circuit voltage), Jsc (short circuit current density) FF (fill factor) and ${\eta}$(solar conversion efficiency) were 0.695 V, $15.81mA\;cm^{-2}$, 61.48% and 6.80%, respectively. In comparison with 5.34% of HP-1 photoelectrode, it was improved by 27.34%.

• The Korean Journal of Physiology and Pharmacology
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• 제7권6호
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• pp.357-362
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• 2003

Carbon monoxide (CO) is low molecular weight oxide gas that is endogenously produced under physiological conditions and interacts with another gas, nitric oxide (NO), to act as a gastrointestinal messenger. The aim of this study was to determine the effects of exogenous CO on L-type calcium channel currents of human jejunal circular smooth muscle cells. Cells were voltage clamped with 10 mM barium ($Ba^{2+}$) as the charge carrier, and CO was directly applied into the bath to avoid perfusion induced effects on the recorded currents. 0.2% CO was increased barium current ($I_{Ba}$) by $15{\pm}2$% ($mean{\pm}S.E.$, p<0.01, n=11) in the cells. To determine if the effects of CO on barium current were mediated through the cGMP pathway, cells were pretreated with 1-H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, $10{mu}M$), a soluble guanylyl cyclase inhibitor, and exogenous CO (0.2%) had no effect on barium currents in the presence of ODQ ($2{\pm}1$% increase, n=6, p>0.05). CO mediates inhibitory neurotransmission through the nitric oxide pathway. Therefore, to determine if the effects of CO on L-calcium channels were also mediated through NO, cells were incubated with $N^G-nitro-L-arginine$ (L-NNA, 1 mM), a nitric oxide synthase inhibitor. After L-NNA pretreatment, 0.2 % CO did not increase barium current ($4{\pm}2$% increase, n=6, p>0.05). NO donor, SNAP ($20{\mu}M$) increased barium current by $13{\pm}2$% (n=6, p<0.05) in human jejunal smooth muscle cells. These data suggest that CO activates L-type calcium channels through NO/cGMP dependant mechanism.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.11.2-11.2
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• 2011

Polymer based organic photovoltaics have attracted a great deal of attention due to the potential cost-effectiveness of light-weight and flexible solar cells. However, most BHJ polymer solar cells are not thermally stable as subsequent exposure to heat drives further development of the morphology towards a state of macrophase separation in the micrometer scale. Here we would like to show three different approaches for developing new electroactive polymers to improve the thermal stability of the BHJ solar cells, which is a critical problem for the commercialization of these solar cells. For one of the examples, we report a new series of functionalized polythiophene (PT-x) copolymers for use in solution processed organic photovoltaics (OPVs). PT-x copolymers were synthesized from two different monomers, where the ratio of the monomers was carefully controlled to achieve a UV photo-crosslinkable layer while leaving the ${\pi}-{\pi}$ stacking feature of conjugated polymers unchanged. The crosslinking stabilizes PT-x/PCBM blend morphology preventing the macro phase separation between two components, which lead to OPVs with remarkably enhanced thermal stability. The drastic improvement in thermal stabilities is further characterized by microscopy as well as grazing incidence X-ray scattering (GIXS). In the second part of talk, we will discuss the use of block copolymers as active materials for WOLEDs in which phosphorescent emitter isolation can be achieved. We have exploited the use of triarylamine (TPA) oxadiazole (OXA) diblock copolymers (TPA-b-OXA), which have been used as host materials due to their high triplet energy and charge-transport properties enabling a balance of holes and electrons. Organization of phosphorescent domains in TPA-b-OXA block copolymers is demonstrated to yield dual emission for white electroluminescence. Our approach minimizes energy transfer between two colored species by site isolation through morphology control, allowing higher loading concentration of red emitters with improved device performance. Furthermore, by varying the molecular weight of TPA-b-OXA and the ratio of blue to red emitters, we have investigated the effect of domain spacing on the electroluminescence spectrum and device performance.

• 대한화학회지
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• 제39권5호
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• pp.329-337
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• 1995

산촉매하에서 중합반응을 하는 고에너지를 함유한 옥세탄 유도체들을 ab initio HF/3-21G 방법으로 구조, 전하, 정전기 전위 등을 계산하고 그 결과를 고찰하였다. 계산 결과에 의하면 큰 치환체가 도입되거나 양성자화나 $BF_3$ 착물화에 의해 옥세탄 고리의 구조는 상당히 변화하며, 이것은 정전기적 상호작용이나 구조적 척력으로 설명할 수 있다. 옥세탄 유도체들의 친핵성 및 염기성은 옥세탄 산소원자의 음전하와 최소 정전기 전위의 크기로 설명할 수 있다. 공중합하의 옥세탄 유도체들의 반응성은 (1) 옥세탄 유도체의 염기성과 (2) 옥세탄 유도체의 HOMO 에너지와 활성화 옥세탄 중합 고리의 LUMO 에너지의 차에 의해 설명되어진다. 계산에 의하면 3-azidomethyl-3-methyl oxetane (AMMO)이 3-nitratomethyl-3-methyl oxetane (NMMO)보다 염기성이 크며, AMMO나 NMMO 사슬에 관계없이 반응성이 큼을 알 수 있다. 이 계산 결과는 이미 알려진 실험 결과들과 잘 일치한다.

• 한국수산과학회지
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• 제48권2호
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• pp.178-186
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• 2015

Protease inhibitors (PI) of trypsin and papain as target proteases from the roe of bastard halibut Paralichthys olivaceus were fractionated out using ammonium sulfate precipitation (A), DEAE 650M anion exchange chromatography (D), and Sephacryl S-300 gel filtration (S). The recovery percentages of the fractions with the strongest inhibitory activity for each fractionation method were 13% for the A4 fraction, 21.2% for the D3 fraction, and 21.3% for the S2 fraction, with specific inhibitory activities of the fractions toward trypsin and casein of 168, 139, and 218 U/mg, respectively, while no inhibition of papain was observed. The $IC_{50}$ for the trypsin-specific substrate $N{\alpha}$-benzoyl-$\small{L}$-arginine-p-nitroanilide (BAPNA) was 0.65, 1.55, 2.26, and 2.85 mg/mL for the A4, S2, A3, and D3 fractions, respectively. These results suggest that chromatographic fractionation methods (D and S) based on the molecular mass and charge of the protein were more effective at fractionating PI than was ammonium sulfate precipitation based on protein solubility, and that the bastard halibut roe extract acts as a serine protease inhibitor. Therefore, the PI fraction from fish roe might be useful for inhibiting proteases in foodstuffs, and could constitute an alternative food-grade inhibitor for the surimi industry.

• BMB Reports
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• 제39권5호
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• pp.530-536
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• 2006

Thermal conformational changes of human serum albumin (HSA) in phosphate buffer, 10 mM at pH = 7 are investigated using differential scanning calorimetric (DSC), circular dichroism (CD) and UV spectroscopic methods. The results indicate that temperature increment from $25^{\circ}C$ to $55^{\circ}C$ induces reversible conformational changes in the structure of HSA. Conformational change of HSA are shown to be a three-step process. Interestingly, melting temperature of the last domain is equal to the maximum value of fever in pathological conditions, i.e. $42^{\circ}C$. These conformational alterations are accompanied by a mild alteration of secondary structures. Study of HSA-SDS (sodium dodecyl sulphate) interaction at $45^{\circ}C$ and $35^{\circ}C$ reveals that SDS affects the HSA structure at least in three steps: the first two steps result in more stabilization and compactness of HSA structure, while the last one induces the unfolding of HSA. Since HSA has a more affinity for SDS at $45^{\circ}C$ compared to $35^{\circ}C$, It is suggested that the net negative charge of HSA is decreased in fever, which results in the decrease of HSA-associated cations and plasma osmolarity, and consequently, heat removal via the increase in urine volume.

• 대한화학회지
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• 제23권3호
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• pp.132-135
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• 1979

1,1,2,2-$C_2H_2F_4$와 1,1,1,2-$C_2H_2F_4$의 아르곤가스와의 묽은 혼합물의 열분해반응을 충격관을 사용 1146와 $1232^{\circ}K$하 전체반사충격압의 3000 torr 근처에서 관찰하였다. 이들 조건하에서 반응은 주로 플루오르화수소의 분자제거반응을 보였다. ${\alpha}$-탄소의 수소가 전부 플루오르로 치환된 이성질체는 다른 이성질체에 비하여 상당히 높은 활성화에너지를 나타내었으며 이는 이성질체간에 전하밀도의 차이에 기인한 것으로 추측된다. 반응속도 상수의 비는 다음식 $log(k_1/k_2) = -0.069 {\pm} 0.021 ＋ (1388{\pm}113)/ 2.303RT$ 로 주어졌으며 이는 독립된 관측을 통해서 얻어진 값들과 좋은 일치를 보여 주었다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 제2회 추계심포지움
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• pp.69-80
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• 1994

Although ureases play important roles in microbial nitrogen metabolism and in the pathogenesis of several human diseases, little is known of the mechanism of metallocenter biosynthesis in this Ni-Containing enzyme. Klebsiella aerogenes urease apo-protein was purified from cells grown in the absence of Ni. The purified apo-enzyme showed the same native molecular weight, charge, and subunit stoichiometry as the holo-enzyme. Chemical modification studies were consistent with histidinyl ligation of Ni. Apo-enzyme could not be activated by simple addition of Ni ions suggesting a requirement for a cellular factor. Deletion analysis showed that four accessory genes (ureD, ureE, ureF, and ureG) are necessary for the functional incorporation of the urease metallocenter. Whereas the $\Delta$ureD, $\Delta$ureF, and $\Delta$ureG mutants are inactive and their ureases lack Ni, the $\Delta$ureE mutants retain partial activity and their ureases possess corresponding lower levels of Ni. UreE and UreG peptides were identified by SDS-polyacrylamide gel comparisons of mutant and wild type cells and by N-terminal sequencing. UreD and UreF peptides, which are synthesized at ve교 low levels, were identified by using in vitro transcription/translation methods. Cotransformation of E. coli cells with the complementing plasmids confirmed that ureD and ureF gene products act in trans. UreE was purified and characterized. immunogold electron microscopic studies were used to localize UreE to the cytoplasm. Equilibrium dialysis studies of purified UreE with $^{63}$ NiC1$_2$ showed that it binds ～6 Ni in a specific manner with a $K_{d}$ of 9.6 $\pm$1.3 $\mu$M. Results from spectroscopic studies demonstrated that Ni ions are ligated by 5 histidinyl residues and a sixth N or O atom, consistent with participation of the polyhistidine tail at the carboxyl termini of the dimeric UreE in Ni binding. With these results and other known features of the urease-related gene products, a model for urease metallocenter biosynthesis is proposed in which UreE binds Ni and acts as a Ni donor to the urease apo-protein while UreG binds ATP and couples its Hydrolysis to the Ni incorporation process.ouples its Hydrolysis to the Ni incorporation process.s.