• 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.

• 폴리머
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• 제32권4호
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• pp.366-371
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• 2008

The controlled/living cationic polymerization of $\alpha$-methylstyrene (${\alpha}MeSt$) and sequential block copolymerization of isobutylene (IB) with ${\alpha}MeSt$ were achieved using 2-chloro-2,4,4-trimethylpentane (TMPCl)/titanium tetrachloride ($TiCl_4$)/titanium isopropoxide ($Ti(OiPr)_4$)/2,6-ditert-butylpyridine (DtBP) initiating system in $CH_3Cl$/hexane(50/50 v/v) solvent mixture at $-80^{\circ}C$. The polymerization rate decreased with increasing $[Ti(OiPr)_4]/[TiCl_4]$ ratio in the homopolymerization of ${\alpha}MeSt$. The effects of $[Ti(OiPr)_4]/[TiCl_4]$ ratios and $PIB^+$ molecular weight on the polymerization rate and blocking efficiency were also investigated. Well-defined poly(isobutylene-b-$\alpha$-methylstyrene)s were demonstrated by $^1H$-NMR and triple detection SEC; refractive index (RI), multiangle laser light scattering (MALLS) and ultraviolet (UV) detectors. Blocking efficiencies for the poly(isobutylene-b-$\alpha$-methylstyrene)s of almost 100% were obtained when ${\alpha}MeSt$ was induced by PIB's of $M_n\;{\geq}\;41000$ at $[Ti(OiPr)_4]/[TiCl_4]=1$. Differential scanning calorimetry (DSC) of the block copolymers showed two glass transition temperatures, thereby demonstrating microphase separation.

• Macromolecular Research
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• 제17권5호
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• pp.346-351
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• 2009

$TiCl(O-i-Pr)_3/SiO_2$ and $Ti(O-i-Pr)_4/SiO_2$ were prepared by immobilizing chlorotitanium (IV) isopropoxide ($TiCl(O-i-Pr)_3$) and titanium (IV) isopropoxide ($Ti(O-i-Pr)_4$), to pretreated silica. The effect of the polymerization reaction conditions on the catalytic activity and characteristics of the resulting PLA were investigated. The catalytic conversion, molecular weight and polydispersity index (PDI) of the PLA produced on the titanium alkoxide supported catalysts increased proportionally with the reaction temperature. When the PLA was synthesized in bulk polymerization, the PLA produced with the supported catalysts had higher molecular weight than those with homogeneous catalysts. The melting temperature of the polymer produced with silica supported alkoxide catalysts was approximately $170-180^{\circ}C$.

• 자원리싸이클링
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• 제23권2호
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• pp.37-45
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• 2014

Nd와 Pr이 함유된 모나자이트 샌드의 염산침출용액에서 Cyanex272 및 PC88A를 기반으로 한 TBP 및 Cyanex272와의 혼합용매를 사용하여 두 금속을 분리하기 위한 용매추출실험을 시행하였다. 이러한 목적을 위해 수상의 pH에 따른 추출제의 농도가 두 금속의 추출 및 분리에 미치는 영향을 조사하였다. 본 연구의 실험범위에서 Nd의 분배계수가 Pr의 분배계수보다 컸다. Cyanex272로 추출하는 경우 추출제의 농도와 초기 pH는 분배계수에 영향을 미치지 않으나, 초기 pH가 증가할수록 분리인자는 증가하였다. 혼합용매의 경우 PC88A를 단독으로 사용했을 때보다 분배계수가 낮고 분리인자에 차이가 없었다.

• 자원리싸이클링
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• 제22권5호
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• pp.35-42
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• 2013

Nd와 Pr이 함유된 염산용액에서 PC88A와 D2EHPA에 의한 두 금속의 분리에 적합한 조건을 조사하기 위해 용매추출실험을 수행하였다. 본 연구의 실험조건에서 Nd의 분배계수가 Pr의 분배계수보다 컸다. PC88A와 D2EHPA로 추출하는 경우 금속과 추출제와의 농도비의 증가가 두 금속의 추출 및 분리에 큰 영향을 미쳤다. D2EHPA의 비누화율과 초기 pH는 두 금속의 추출에는 큰 영향을 미치지만, 분리인자에는 큰 변화가 없었다.

• Bulletin of the Korean Chemical Society
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• 제21권6호
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• pp.638-640
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• 2000

• 한국전기전자재료학회논문지
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• 제11권8호
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• pp.646-651
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• 1998

In this present study, the luminescence characteristics and mechanism of energy $CaTiO_3$:Pr phosphor were studied using disk specimens sintered at various temperatures and envirenment. A single-phase $CaTiO_3$:Pr was synthesized by sintering above 140$0^{\circ}C$ and its crystal structure was found to be perovskite orthorhombic. A dominant peak around 360 nm and a broad peak around 395 nm were observed in the PLE(Photoluminescence Excitation) spectrum of $CaTiO_3$:Pr with fixed emission wavelength at 612 nm, the decay time of 360 nm excitation was found to be longer than that of 395 nm excitation. From this result, it is assumed that the free carrier excited to 360 nm is transferred to 395 nm energy level. Therefore, the decrease in 395 nm intensity observed in CaTiO$_3$:Pr specimens sintered in Ar gas environment induced shorter decay time and improved CL luminescence.

• 응용화학
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• 제15권2호
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• pp.85-88
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• 2011

We synthesized ethylene-styrene copolymer by coordination polymerization using 2 types of pyrazolato metallocene catalysts ((1,2,4-Me₃C₅H₄)TiCl₂(3,5-iPr₂C₃HN₂), (tert-BuC₅H₄) TiCl₂(3,5-iPr₂C₃HN₂)). We observed the effects of styrene concentration on the catalytic activity, yield, molecular weight and molecular weight distribution.

• 한국균학회지
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• 제23권3호통권74호
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• pp.202-208
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• 1995

본 실험결과 느타리버섯속에서의 재현성 있는 최적 RAPD 조건은 $50\;{\mu}l$ 반응액에서 80 ng template DNA, 30 pmole primer, $200\;{\mu}M$ dNTP, 2 mM $MgCl_2$, 50 mM KCl, 10 mM Tris-HCI(pH 9.0), 0.1% Triton X-100, 1.5 unit Taq polymerase(promega)였다. 여섯 개의 primer가 Pleurotus속 8종의 균주에서 RAPD polymorphism을 보임을 알 수 있었으며, 이들의 염기배열은 PR2(GGG GGG AAG C), PR3(GCG GTT GAG G), PR4(CGC ACC GCA C), PR10(CAA TCG CCG T), PR11(CAG CAC CCA C), PR17(TAG GCG TAT CAG GAG GCC CT)이었다.

• 대한화학회지
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• 제48권6호
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• pp.577-582
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• 2004

새로운 아자크라운 화합물인, 1,4-dioxa-7,10,13-triazacyclopentadecane-N,N',N''-triacetic acid, $N-ac_3[15]aneN_3O_2(II_a)$과 1,4-dioxa-7,10,13-triazacyclopentadecane-N,N',N''-tripropioc acid, $N-pr_3$[15]ane$N_3O_2(II_b)$는 이와 유사한 화합물의 합성방법을 수정하여 합성하였다. 합성된 이 아자크라운 화합물, $N-ac_3[15]aneN_3O_2와\;N-pr_3[15]aneN_3O_2$의 양성자화 상수값은 전위차법을 이용하여 PKAS 프로그램으로부터 측정되어졌다. 그리고 0.1 M $NaClO_4$수용액으로 이온강도를 조절하고, $25{\pm}0.1^{\circ}C$에서 란탄족금속인, $Ce^{3+},\;Eu^{3+},\;Gd^{3+}$ 및 $Yb^{3+}$과 리간드인 $N-ac_3[15]$ane$N_3O_2$와 $N-pr_3[15]aneN_3O_2$의 착물의 안정도상수를 전위차법을 이용하여 BEST 프로그램으로부터 구하였고, 또한 위와 같은 조건에서 전이금속인 $Co^{2+}$, $Ni^{2+}$, $Cu^{2+}$및 $Zn^{2+}$와 리간드인, $N-ac_3[15]aneN_3O_2$와 $N-pr_3[15]aneN_3O_2$의 착물의 안정도상수 값도 전위차법을 이용하여 BEST 프로그램으로부터 측정하였다. 합성된 아자크라운 화합물과 골격구조가 유사하고 아세트산과 프로피온산기를 포함하는, 1,7-dioxa-4,10,13-triazacyclopentadecane-N,N',N''-triacetic acid과 1,7-dioxa-4,10,13-triazacyclopentadecane-N,N',N''-tripropioc acid의 착물의 안정도를 비교분석하였다.