• 대한화학회지
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• 제37권10호
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• pp.895-902
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• 1993

란탄나이드 3가($Pr^{3+}$ 와 $Dy^{3+}$)와 유기 리간드를 (phen', terpy') 착물들의 거동을 UV/vis 분광분석, 자기화 그리고 전기화학적 방법에 의해 조사하였다. 착물들의 결정장 갈라짐 에너지 크기와 짝지움에너지 그리고 스핀상태는 착물들의 스펙트라로부터 얻었다. 이들 착물들에 대한 전지화학적 거동은 비수용매속에서 순환 전압전류법에 의해 관찰하였다. 이들 환원피크는 전자 전이에 의한 비가역적인 2단계의 환원 과정이었다.

• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2980-2984
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• 2010

A new poly (vinyl chloride) (PVC) membrane electrode that is highly selective to $Mn^{+2}$ ions was prepared using N,N'-bis(2'-pyridinecarboxamide)-1,2-ethane ($bpenH_2$) as a suitable neutral carrier. This concentration range ($1.0{\times}10^{-5}$ to $1.0{\times}10^{-1}\;M$) with Nernstian slope of $29.3{\pm}0.5\;mV$ per decade. The detection limit and the response time of electrode were $8.0{\times}10^{-6}\;M$ and (${\leq}15\;s$) respectively. The membrane can be used for more than two months without observing any divergence. The electrodes exhibited excellent selectivity for $Mn^{+2}$ ion over other mono-, di- and trivalent cations. Selectivity coefficients were determined by the matched potential method (MPM). The electrode can be used in the pH range from 4.0 - 9.0. The isothermal coefficient of this electrode amounted to 0.00023 V/$^{\circ}C$. The stability constant (log $K_s$) of the $Mn^{+2}$ - $bpenH_2$ complex was determined at $25^{\circ}C$ by potentiometric titration in mixed aqueous solution. The proposed electrode was applied to the determination of $Mn^{+2}$ ions in real samples.

• Bulletin of the Korean Chemical Society
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• 제25권6호
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• pp.852-858
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• 2004

Crystal structures of lanthanide complexes with NTA (NTA = nitrilotriacetate) are reported. The complexes of $[Ln(NTA)_2{\cdot}H_2O]^{3-}$ (Ln = Sm, Eu, Gd, Tb and Ho) crystallize in the orthorhombic space group Pccn. In the structures, the trivalent lanthanide ions are completely encapsulated via coordination to the two nitrogen atoms and the six carboxylate oxygen atoms of the two NTA ligands, and one water oxygen atoms. The complexes form a slightly distorted capped-square-antiprism polyhedron. Of the complexes, $[Eu(NTA)_2{\codt}H_2O]^{3-}$,\;[Tb(NTA)_2{\cdot}H_2O]^{3-}\;and\;[Dy(NTA)_2{\cdot}H_2O]^{3-}$ excited at the 325 He-Cd line produce very characteristic luminescence features, arising mostly from the f ${\to}$ f transitions. The absolute quantum yields of these complexes are determined at room temperature. Surprisingly, the $[Dy(NTA)_2{\cdot}H_2O]^{3-}$ complex is more luminescent than the $[Eu(NTA)_2{\cdot}H_2O]^{3-}\;and\;[Tb(NTA)_2{\cdot}H_2O]^{3-}$ complexes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.361-361
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• 2007

A lot of efforts have been paid to develop infrared imaging systems in last decades. Bolometer has a wide range of applications from military to commercial, such as military night vision, medical imaging system and so on. Bolometer is a resistive sensor that detects temperature changes through resistance change. To improve detecting ability, bolometer should have a good resistive film which has high temperature coefficient of resistance (TCR) value. Colossal magnetoresistance (CMR) $L_{1-x}A_xMnO_3$ (where L and A are trivalent rare-earth ions and divalent alkaline earth ions, respectively.) are received attention to apply bolometer resistive film because it has a high TCR property which was discovered in the metal to semiconductor phase transition temperature region. In this work, CMR films were deposited on various substrates in relative low substrate temperature by RF magnetron sputtering. The influence of deposition parameters such as substrate temperature, gas partial pressure, and so on have been studied. The structural and TCR properties of the films were also investigated for applying to microbolometer.

• Nuclear Engineering and Technology
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• 제31권5호
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• pp.498-505
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• 1999

Trivalent actinide-lanthanide group separation is difficult to perform on an industrial scale, because of the many drawbacks of the available chemical process. In this paper, picolinamide(C$_{8}$H$_{17}$) is synthesized and characterized, and extraction yields of Am-241, Eu-152 and Nd are determined in batch extraction experiments. In particular, the influence of the solvent is described. The extraction yields of Am-241, Eu-152 and Nd depended on the LiNO$_3$ concentration, the picolinamide(C$_{8}$H$_{17}$) concentration and the acidity. A favorable picolinamide(C$_{8}$H$_{17}$) concentration was found to be about 2M. The appropriate nitric acid concentration and LiNO$_3$ concentration were confirmed to be about 0.125M and 3M, respectively. The separation factor of Am and Eu was about 9.9 at optimum conditions. The picolinamide(C$_{8}$H$_{17}$) is a very promising extractant for the actinide(III)-lanthanides(III) separation.aration.aration.

• 소성∙가공
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• 제12권5호
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• pp.493-497
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• 2003

The present investigation aims at visualizing the crack tip stress field using a mechanoluminescence material. The well known compound $SrAl_2O_4$:$Eu^{2+}$ was adopted as a mechanolurninescence material. Two more trivalent rare-earth elements such as Dy and Nd were taken into consideration as codopants to provide the appropriate trap levels. Samples of a variety of compositions were prepared by varing $Eu^{2+}$, $Dy^{3+}$, and $Nd^{3+}$ doping contents, for which the combinatorial chemistry method was used. In order to search for the optimum composition for the highest mechanoluminescence, the luminescence induced by a compressive device including a CCD camera. In parallel, a compact tension specimen was prepared by mixing the luminescence powders of optimum composition and epoxy resin. Crack initiation from the mechanically machined sharp note tip and its growth during loading were found to be associated with the extent of light emission from $SrAl_2O_4$.

• Bulletin of the Korean Chemical Society
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• 제11권6호
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• pp.564-567
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• 1990

A lithiated compound $Li_{0.1}Pr^{3+}Ba_2Cu_3O_y$ has been successfully prepared by electrochemical method, which is achieved with a two electrode cell of the type: Metal(Li)/($Li^+\;,\;ClO_4^-$) + propylene carbonate/$PrBa_2Cu_3O_y$. All Pr ions in the lithiated compound are stabilized with a trivalent state as the other rare earths (Ⅲ) substituted in the 90K superconductor lattice ($Y_{1-x}Ln_x^-Ba_2Cu_3O_{7-{\delta}}$). Powder X-ray diffraction analysis shows that both compounds, $PrBa_2Cu_3O_y$ and $Li_{0.1}PrBa_2Cu_3O_y$ are isostructural with the 90 K superconductor, ($YBa_2Cu_3O_{7-{\delta}}$), nevertheless both of them are non-metallic and also non-superconducting down to 10 K. Magnetic susceptibility ${\chi}$ vs. temperature data indicate that Curie contribution from the magnetic ions (Pr and Cu) is weakened on the one hand, but on the other hand temperature-independent part of susceptibility ${\chi}_o$ increases depending upon the rate of lithium intercalation in $PrBa_2Cu_3O_y$ lattice.

• Toxicological Research
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• 제35권4호
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• pp.311-317
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• 2019

The transport systems for metals play crucial roles in both the physiological functions of essential metals and the toxic effects of hazardous metals in mammals and plants. In mammalian cells, Zn transporters such as ZIP8 and ZIP14 have been found to function as the transporters for Mn(II) and Cd(II), contributing to the maintenance of Mn homeostasis and metallothionein-independent transports of Cd, respectively. In rice, the Mn transporter OsNramp5 expressed in the root is used for the uptake of Cd from the soil. Japan began to cultivate OsNramp5 mutant rice, which was found to accumulate little Cd, to prevent Cd accumulation. Inorganic trivalent arsenic (As(III)) is absorbed into mammalian cells via aquaglyceroporin, a water and glycerol channel. The ortholog of aquaporin in rice, OsLsi1, was found to be an Si transporter expressed in rice root, and is responsible for the absorption of soil As(III) into the root. Since rice is a hyperaccumulator of Si, higher amounts of As(III) are incorporated into rice compared to other plants. Thus, the transporters of essential metals are also utilized to incorporate toxic metals in both mammals and plants, and understanding the mechanisms of metal transports is important for the development of mitigation strategies against food contamination.

• Bulletin of the Korean Chemical Society
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• 제9권5호
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• pp.289-291
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• 1988

The ratio of trivalent to divalent copper has been determined by the redox titration for two superconducting phases of $YBa_2Cu^{3+}_{2x}Cu^{2+}_{3-2x}O_{6.5+x}$ with the onset temp. of 60K (x = 0.23 ${\pm}$ 0.01) and 90K (x = 0.35 ${\pm}$ 0.02), and for the insulating one (x ${\cong}$ 0) which was kept in an ambient atmosphere for 72 hrs. It is found that $T_c$, and the ratio of $Cu^{3+}/Cu^{2+}$ depend strongly on the annealing temperature and time. A typical orthorhombic phase can easily be obtained by a slow cooling or stepwise cooling at $PO_2$ = 1 atm, and shows a high Tc (ca. 90K) superconductivity.

• Asian-Australasian Journal of Animal Sciences
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• 제22권10호
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• pp.1414-1419
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• 2009

The study was conducted to evaluate the effects of trivalent chromium from different sources on growth, carcass composition, and serum parameters in finishing pigs. Ninety-six crossbred pigs with an initial average body weight of 65.57${\pm}$1.05 kg were blocked by body weight and randomly assigned to four treatments with three replicates. Pigs were offered one of four diets including a control diet or the control diet supplemented with 200 ${\mu}g/kg$ chromium from either chromium chloride ($CrCl_{3}$), chromium picolinate (CrPic) or chromium nanocomposite (CrNano) for 40 days. After completion of the feeding trial, eight pigs from each treatment were selected to collect blood samples, and slaughtered to measure carcass composition. The results showed that supplemental chromium had no significant effect on growth performance, while CrNano increased carcass lean proportion and loin Longissimus muscle area (p<0.05), and decreased carcass fat proportion and 10th rib backfat depth (p<0.05). CrPic supplementation also resulted in lower fat proportion and larger Longissimus muscle area (p<0.05). The addition of Cr from CrNano or CrPic decreased serum glucose (p<0.05) and increased concentrations of total protein and free fat acid in serum (p<0.05). Serum urea nitrogen, triglyceride and cholesterol were decreased (p<0.05), and serum high density lipoprotein and lipase activity were increased (p<0.05) with the supplementation of CrNano. Serum insulin was decreased (p<0.05) by supplemental Cr from CrNano or CrPic, and serum insulin-like growth factor I was increased significantly in the CrNano treated group. These results suggest that chromium nanocomposite has higher efficacy on carcass composition in pigs compared to the traditional chromium sources.