• Journal of Photoscience
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• 제10권1호
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• pp.127-148
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• 2003

Zeolite is a porous highly interactive matrix. Zeolitic cations help to generate triplets from molecules that possess poor intersystem crossing efficiency. Certain zeolites act as electron acceptors and thus can spontaneously generate radical cations. Zeolites also act as proton donors and thus yield carbocations without any additional reagents. These reactive species, radical cations and carbocations, have long lifetime within a zeolite and thus lend themselves to be handled as ‘regular’ chemicals. Internal structure of zeolites is studded with cations, the counter-ions of the anionic framework. The internal constrained structure and the cations serve as handles for chemists to control the behavior of guest molecules included within zeolites.

• Archives of Pharmacal Research
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• 제29권7호
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• pp.605-616
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• 2006

A wide variety of drugs and endogenous bioactive amines are organic cations (OCs). Approximately 40% of all conventional drugs on the market are OCs. Thus, the transport of xenobiotics or endogenous OCs in the body has been a subject of considerable interest, since the discovery and cloning of a family of OC transporters, referred to as organic cation transporter (OCTs), and a new subfamily of OCTs, OCTNs, leading to the functional characterization of these transporters in various systems including oocytes and some cell lines. Organic cation transporters are critical in drug absorption, targeting, and disposition of a drug. In this review, the recent advances in the characterization of organic cation transporters and their distribution in the small intestine are discussed. The results of the in vitro transport studies of various OCs in the small intestine using techniques such as isolated brush-border membrane vesicles, Ussing chamber systems and Caco-2 cells are discussed, and in vivo knock-out animal studies are summarized. Such information is essential for predicting pharmacokinetics and pharmacodynamics and in the design and development of new cationic drugs. An understanding of the mechanisms that control the intestinal transport of OCs will clearly aid achieving desirable clinical outcomes.

• 한국물환경학회지
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• 제25권1호
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• pp.151-158
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• 2009

The objective of this study was to determine on optimum ratio of oxidant and catalyst and to evaluate affecting factors such as anions and cations on persulfate oxidation of organic pollutant. Fe(II) activated the persulfate anion to produce a sulfate free radicals and thus effectively used to degrade the target organic pollutant in aqueous system. The chloride ions reacted with sulfate radical produced the $Cl^{\cdot}$ atom and had positive effects on the oxidation of organic pollutant at the initial stage. However, it was observed that chloride ions had the scavenging effects on the rate of oxidation of organic pollutant. Cations and some heavy metals were partly able to activate the persulfate anion to generate a sulfate free radical. However, high levels of cations inhibited the oxidation of organic pollutant.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.415.1-415.1
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• 2002

Apical to basal transport of organic cations (OCs) such as tributylmethylammonium (TBuMA), triethyimethylammonium (TEMA). 1-methyl-4-phenylpyridinium (MPP), and berberine across Caco-2 cell monolayers was measured to elucidate the intestinal absorption of OCs. Basal to apical transport of MPP and berberine was larger than apical to basal transport and showed temperature dependency and concentration dependency. indicating that MPP and berberine are secreted into the inteslinal lumen. (omitted)

• 한국토양비료학회지
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• 제19권2호
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• pp.139-145
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• 1986

담배식물이 흡수한 질산태질소가 조직중(組織中)에서 환원 되므로서 양(陽)이온과 음(陰)이온성분간(成分間)의 평형(平衡)에 미치는 영향을 구명하기 위하여 질소원(窒素源)을 달리한 배양액(培養液)으로 재배(栽培)하면서 무기(無機) 양음(陽陰)이온총량차이(總量差異)를 조사하고 질소환원(窒素還元) 및 유기산함량(有機酸含量)의 변화(變化)와 이온총량차이(總量差異)와의 관계(關係)를 검토(檢討)한 결과(結果) 1. $NO_3-N$ 배양액에서 자란 식물은 $NH_4-N$ 배양액의 것보다 양(陽)이온총량(總量)이 높았다. 무기음(無機陰)이온총량(總量)은 $NO_3+NH_4$혼합배양액(混合培養液)에서 가장 높게 나타났으나 $NO_3-N$ 배양액에서 가장 낮아서 무기 양음(陽陰)이온총량차이(總量差異)가 가장 컸고 $NH_4{^+}$가 함유된 배양액에서는 무기양음이온 총량차이가 비슷하여 무기이온으로서 거의 이온균형(均衡)이 유지(維持)되었다. 2. 식물체중(植物體中) 유기산(有機酸)은 malic acid의 분포가 가장 컸으며 $NO_3-N$ 배양액식물은 유기산(有機酸)이 다량함유(多量含有)되어 있으나 $NH_4-N$ 또는 혼합배양액(混合培養液)의 것은 거의 검출(檢出)되지 않았다. $NO_3-N$ 배양액식물(培養液植物)은 유기산총량(有機酸總量)이 무기음(無機陰)이온 총량(總量)보다 초과(超過)되어 유기산(有機酸)에 의한 이온균형(均衡)비율이 크나 $NH_4-N$ 배양액식물은 이온균형(均衡)에 차지하는 유기산(有機酸)비율이 극히 소량이었다. 3. $NO_3-N$식물(植物)은 질산환원(窒酸還元)이 왕성하게 진행되므로서 유리(遊離)된 양(陽)이온과의 이온균형(均衡)을 위하여 유기산(有機酸)이 다량(多量) 함유(含有)되었다.

• 한국토양비료학회지
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• 제19권3호
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• pp.223-229
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• 1986

1. 질산염영양액(窒酸鹽營養液)으로 관수(灌水)하여 재배(栽培)한 담배식물(cv. NC82)의 엽서별(葉序別) 이온균형(均衡)을 조사(調査)한 결과(結果) 무기양(無機陽)이온과 무기음(無機陰)이온의 총량(總量)은 출엽순서별(出葉順序別)로 차이(差異)가 있어 하위엽(下位葉)에서는 무기양(無機陽)이온이 무기음(無機陰)이온보다 3배(倍)이상 차이(差異)(5차엽(次葉))를 보이나 상위(上位)의 어린잎(10차엽(次葉))에서는 1.3배(倍)로 떨어졌다. 2. 양(陽)이온의 대부분은 $K^+$, $Ca^{{+}{+}}$, $Mg^{{+}{+}}$이었으며 K+Ca는 출엽(出葉)된 모든 잎에서 양(陽)이온의 80%정도로 일정한 비율이 유지되었다. 그 구성비율(構成比率)은 오랜잎일수록 $Ca^{{+}{+}}$ 높고 엽령(葉齡)이 커질수록 증가(增加)하나, 어린잎 쪽에서는 $K^+$의 비율이 높으며 엽령(葉齡)에 따라 점차 낮아지는 경향이었다. 3. 양(陽)이온총량(總量)은 무기음(無機陰)이온과 유기산(有機酸) 음(陰)이온으로 이온균형(均衡)이 유지(維持)되었으며 하엽(下葉)에서는 유기산(有機酸) 음(陰)이온에 의존(依存)한 이온균형(均衡)이 무기음(無機陰)이온보다 컸으나 상엽(上葉)으로 갈수록 점차 반대 경향으로 나타났다. 4. 이온총량(總量)이 큰 하엽(下葉)에서는 양음(陽陰)이온 총량(總量) 차이(差異)가 나타났으나 상엽(上葉)에서는 균형(均衡)이 거의 유지(維持)되었다. 하엽(下葉)의 이온총량차(總量差)는 일부(一部) 유기산석회염(有機酸石灰鹽)이 침전(沈澱)되어서 수산(蓚酸)이 검출되지 않았기 때문인 것 같다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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• pp.18-18
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• 2003

Natural clays are composed of oxide layers whose thickness is about 1nm and cations existing between the layers. A number of these layers makes primary particles with a height of about 8∼10nm and these primary particles make aggregates with a size of about 0.1∼10$\mu\textrm{m}$. When layered silicate was made to be organophilic, by exchanging the interlayer cations with organic cationic molecules, the matrix polymer can penetrate between the layers to give a nanocomposite, where 1nm-scal clay layers exist separately in a continuous polymer matrix. These nanostructured hybrid organic-inorganic composites have attracted the great interest of researchers over the last 10 years. They exhibit improved performance properties compared with conventional composites, because their unique phase morphology by layer intercalation or exfoliation maximizes interfacial contact between the organic and inorganic phases and enhances interfacial properties. Since the advent of nylon-6/montmorillonite nanocomposite developed by Toyota Motor Co., the studies on layered silicate-polymer nanocomposites have been successfully extended to other polymer systems. They greatly improved the thermal, mechanical, barrier, and even the flame-retardant properties of the polymers.

• The Korean Journal of Ecology
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• 제23권2호
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• pp.83-88
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• 2000

When interpreting change over time in forest ecosystems, distinguishing the effects of forest succession from the effects of environmental stress can be difficult. The result may be a simplistic interpretation. citing a specific successional or environmental cause of forest change when both types may be occurring. We present two case studies of changes in the forest floor in northern hardwoods. First, the belief that 50% of soil organic matter is lost in the first 20 years after logging was based on a study comparing northern hardwood stands of different ages. We resampled a series of 13 such stands after an interval of 15 years, and found that the young stands were not, in fact. losing organic matter as rapidly as predicted from the original chronosequence study. The pattern of higher organic matter content in the forest floors of older stands compared to young stands could be equally well explained by changes in logging practices over the last century as by the aging of the stand. The observed pattern of forest floor organic matter as a function of stand age was previously interpreted as a successional pattern, ignoring changes in treatment history. In the second case study, observed losses of base cations from the forest floor were attributed to cation depletion caused by acid rain and declining calcium deposition. We found that young stands were gaining base cations in the forest floor; losses of base cations were restricted to older stands. Differences in litter chemistry in stands of different ages may explain some of the pattern in cation gains and losses. In this case, the contribution of successional processes to cation loss had been overlooked in favor of environmental stress as the dominant mechanism behind the observed changes. Studies of environmental stress use repeated measures over time. but often don't consider stand age as a factor. Studies of successional change often assume that environmental factors remain constant. We were able to consider both forest succession and external factors because we repeatedly sampled stands of different ages.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2011년도 제44차 학술발표회
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• pp.36-36
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• 2011

We synthesized new dye sensor based on indole compound. Through the UV-vis absorptions, we analyzed chemosensing properties to explain metal binding properties. The peak absorptions increased at 472 nm when added metal cations($Cd^{2+}$, $Cu^{2+}$, $Hg^{2+}$, $Fe^{2+}$, $Zn^{2+}$, $Ni^{2+}$ and $Cr^{3+}$) and gradually decreased the peak at 516 nm. Thus, this UV-Vis absorption behavior clearly showed the metal binding reaction. To measure energy level of used dye sensor, HOMO/LUMO energy value was calculated with cyclovaltagramm(CV) and using computational calculation method, in which we estimated the optimum structure of dye sensor. CV and computational calculation method, both compared to find suitable geometric structure. (with almost same energy values.) From the computational calculation, dye sensor has plane structure. So, Amine and ketone in the dye sensor faced each other and makes position to bind metal cations. In addition, these positions was supported pull-push electron system and generated MLCT process, when the dye sensor was bonded with the metal cations and resulted chemosensing properties. Through the electrochemical and computational calculation method analyze, we proposed the chemosensing principles that the dye sensor bind the metal cation between ketone and amine. Finally, the formation type of metal ion bindings was determined by Job's plot measurements.

• 한국산업융합학회 논문집
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• 제19권4호
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• pp.176-184
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• 2016

Electrochemical ion exchange method is expected to be one of the most acceptable techniques for the separation of radioactive cations from nuclear wastewater. In this study a thin film of hexacyanoferrate on nickel surface was derivatized chemically in an aqueous potassium-ferricyanide solution. Electrochemical redox behavior of the nickel hexacyanoferrate(NiHCNFe) film electrode was investigated with the use of cyclic voltammetry potentiostated from -100 to 800 mV versus SCE. The electro-reduction characteristics of the NiHCNFe film were examined in the cobalt solutions. The NiHCNFe ion exchanger was more useful at lower concentration, lower temperature, and pH7 of the cobalt solution. The capacity loss of NiHCNFe was 0.018%/cycle that was less than the average loss of 2~3%/cycle of the convective organic exchanger. The 45~55% of the initial cobalt ions was electro-deposited on the NiHCNFe by using continuous recirculating reactor system. As a result, it was found that the electroactive NiHCNFe films showed better performance than the organic resins for the separation of cobalt ion from the aqueous solutions.