• 한국세라믹학회지
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• 제52권6호
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• pp.514-520
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• 2015

$KY_{1-x}(WO_4)_2:Ho^{3+}/Yb^{3+}$ yellow phosphors with doping concentrations of $Ho^{3+}$ and $Yb^{3+}$ ($x=Ho^{3+}+Yb^{3+}$, $Ho^{3+}=0.05$, 0.1, 0.2 and $Yb^{3+}=0.2$, 0.45) were successfully prepared using the microwave-modified sol-gel method; their upconversion (UC) photoluminescence properties were investigated in detail. Well-crystallized particles, formed after heat-treatment at $900^{\circ}C$ for 16 h, showed a fine and homogeneous morphology with particle sizes of $2-5{\mu}m$. Under excitation at 980 nm, the UC $KY_{0.7}(WO_4)_2:Ho_{0.1}Yb_{0.2}$ and $KY_{0.5}(WO_4)_2Ho_{0.05}Yb_{0.45}$ particles exhibited excellent yellow emissions based on a strong 545-nm emission band in the green region and a very strong 655-nm emission band in the red region. Pump power dependence and Commission Internationale de L'Eclairage chromaticity of the UC emission intensity were evaluated. The spectroscopic properties were examined comparatively using Raman spectroscopy.

• 한국세라믹학회지
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• 제52권1호
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• pp.66-71
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• 2015

$NaY_{1-x}(WO_4)_2:Ho^{3+}/Yb^{3+}$ phosphors with doping concentrations of $Ho^{3+}$ and $Yb^{3+}$ ($x=Ho^{3+}+Yb^{3+}$, $Ho^{3+}=0.05$, 0.1, 0.2, and $Yb^{3+}=0.2$, 0.45) were successfully synthesized via the cyclic microwave-modified sol-gel route; their upconversion properties were investigated. Well-crystallized particles showed a fine and homogeneous morphology with particle sizes of $2-5{\mu}m$. Under excitation at 980 nm, the synthesized particles exhibited yellow emissions based on a strong 550-nm emission band in the green region and a very strong 655-nm emission band in the red region. The Raman spectra of the doped particles indicated the domination of strong peaks at higher and lower frequencies induced by the incorporation of the $Ho^{3+}$ and $Yb^{3+}$ elements into the $Y^{3+}$ sites in the crystal lattice, which resulted in unit cell shrinkage that accompanied a new phase formation of the $WO_{4-x}$ group.

• Transactions on Electrical and Electronic Materials
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• 제18권6호
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• pp.364-369
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• 2017

Double molybdate $NaGd_{1-x}(MoO_4)_2:Ho^{3+}/Yb^{3+}$ phosphors with proper doping concentrations of $Ho^{3+}$ and $Yb^{3+}$ ($x=Ho^{3+}+Yb^{3+}$, $Ho^{3+}=0$ and 0.05, and $Yb^{3+}=0$, 0.35, 0.40, 0.45, and 0.50) were successfully synthesized using the microwave sol-gel method. Well-crystallized particles formed after heat-treatment at $800^{\circ}C$ for 16 h showed fine and homogeneous morphologies with particle sizes of $1{\sim}3{\mu}m$. The spectroscopic properties were examined using photoluminescence emission and Raman spectroscopy. Under excitation at 980 nm, the upconversion doped samples exhibited strong yellow emissions, from the combination of strong emission bands at 545 nm and 655 nm in the green and red spectral regions, respectively. The strong 545 nm emission band in the green region corresponded to the $^5S_2/^5F_4{\rightarrow}^5I_8$ transition in the $Ho^{3+}$ ions, while the strong 655 nm band in the red region appeared because of the $^5F_5{\rightarrow}^5I_8$ transition in the $Ho^{3+}$ ions. The pump power dependence and the Commission Internationale de L'Eclairage chromaticity of the upconversion emission intensity were evaluated in detail.

• 한국재료학회지
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• 제26권1호
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• pp.29-34
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• 2016

$NaLa_{1-x}{(MoO_4)}_2$:$Ho^{3+}/Yb^{3+}$ phosphors with the correct doping concentrations of $Ho^{3+}$ and $Yb^{3+}$ ($x=Ho^{3+}+Yb^{3+}$, $Ho^{3+}=0.05$ and $Yb^{3+}=0.35$, 0.40, 0.45 and 0.50) were successfully synthesized by the microwave-modified sol-gel method. Well-crystallized particles formed after heat-treatment at $900^{\circ}C$ for 16 h showed a fine and homogeneous morphology with particle sizes of $3-5{\mu}m$. The optical properties were examined using photoluminescence emission and Raman spectroscopy. Under excitation at 980 nm, the UC intensities of the doped samples exhibited strong yellow emissions based on the combination of strong emission bands at 545-nm and 655-nm emission bands in green and red spectral regions, respectively. The strong 545-nm emission band in the green region corresponds to the $^5S_2/^5F_4{\rightarrow}^5I_8$ transition in $Ho^{3+}$ ions, while the strong emission 655-nm band in the red region appears due to the $^5F_5{\rightarrow}^5I_8$ transition in $Ho^{3+}$ ions. Pump power dependence and Commission Internationale de L'Eclairage chromaticity of the upconversion emission intensity were evaluated in detail.

• 분석과학
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• 제27권6호
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• pp.314-320
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• 2014

$La_{2-x}(MoO_4)_3:Er^{3+}/Yb^{3+}$ particles with doping concentrations of $Er^{3+}$ and $Yb^{3+}$ ($x=Er^{3+}+Yb^{3+}$, $Er^{3+}$=0.05, 0.1, 0.2 and $Yb^{3+}$ = 0.2, 0.45) were successfully prepared by the microwave-modified sol-gel method, and the upconversion photoluminescence properties were investigated. Well-crystallized particles, formed after heat-treatment at $900^{\circ}C$ for 16 h, showed a fine and homogeneous morphology with particle sizes of $2-5{\mu}m$. Under excitation at 980 nm, $La_{1.7}(MoO_4)_3:Er_{0.1}Yb_{0.2}$ and $La_{1.5}(MoO_4)_3:Er_{0.05}Yb_{0.45}$ particles exhibited a strong 525 nm emission band, a weak 550 nm emission band in the green region, and a very weak 655 nm emission band in the red region. The Raman spectra of the doped particles indicated the presence of strong peaks at higher frequencies of 752, 846, 922, 1358 and $1435cm^{-1}$ and lower frequency of $314cm^{-1}$ induced by the disorder of the $[MoO_4]^{2-}$ groups with the incorporation of the $Er^{3+}$ and $Yb^{3+}$ elements into the crystal lattice or by a new phase formation.

• 한국재료학회지
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• 제26권7호
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• pp.363-369
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• 2016

$NaCaLa_{1-x}(MoO_4)_3:Ho^{3+}/Yb^{3+}$ ternary molybdates with proper doping concentrations of $Ho^{3+}$ and $Yb^{3+}$ (x = $Ho^{3+}+Yb^{3+}$, $Ho^{3+}$ = 0.05 and $Yb^{3+}$ = 0.35, 0.40, 0.45 and 0.50) were successfully synthesized by microwave sol-gel method. Well-crystallized particles formed after heat-treatment at $900^{\circ}C$ for 16 h showed a fine and homogeneous morphology with particle sizes of $3-5{\mu}m$. Under excitation at 980 nm, the UC intensities of the doped samples exhibited strong yellow emissions based on the combination of strong emission bands at 520-nm and 630-nm emission bands in the green and red spectral regions, respectively. The optimal $Yb^{3+}:Ho{3+}$ ratios were obtained at 9:1 and 10:1, as indicated by the composition-dependent quenching effect of the $Ho^{3+}$ ions. The pump power dependence of the upconversion emission intensity and the Commission Internationale de L'Eclairage chromaticity coordinates of the phosphors were evaluated in detail.

• Journal of Microbiology and Biotechnology
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• 제2권1호
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• pp.14-20
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• 1992

Some microorganisms isolated from soil, including some bacteria and fungi, were found to secrete an extracellular soymilk-clotting enzyme. Among them, an isolated fungus showed the highest soymilk-clotting activity and the strain was assigned to genus Penicillium based on its cultural and morphological characteristics, and designated as Penicillium sp. L-151K. Soymilk-clotting enzymes A and B produced by Penicillium sp. L-151K were purified by ammonium sulfate precipitation and chromatographies on Sephadex G-25, CM-Sephadex, Sephadex G-100 and phenyl-Toyopearl gel. The two purified enzymes A and B were found to be homogeneous by polyacrylamide gel electrophoresis at pH 9.5. The molecular weights of enzyme A and B were 24, 000 and 40, 000, respectively, by gel filtration on Sephadex G-100. Enzymes A and B coagulated soymilk optimally at $60^\circ{C}$ and were stable up to $50^\circ{C}$. Both enzymes were most active at pH 5.8 for soymilk coagulation, and were stable with approximately 80% of original activity from pH 3.0 to 5.0. Each enzyme was an acidic protease with an optimum pH of 3.0 for casein digestion. The soymilk-clotting efficiency of these enzymes was improved with $CaCl_2\;or\;MgCl_2$ when making soymilk-curd.

• 한국식품과학회지
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• 제20권6호
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• pp.856-861
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• 1988

본 실험은 Staphylococcus aureus의 한 균주로부터 A와 C, 두 종류의 toxin이 동시에 생성될 때 이들의 동시분리를 위하여 각종 분리방법을 연구하였다. 혼합된 toxin A와 C는 CM-column chromatography를 이용하여 pH-gradient법으로 용출했을 때 2개의 분획이 나타났으나 서로 완전히 분리되지 않아 다량의 서로 다른 toxin이 함유되어 있었고 Sephadex G-75, Sephacryl S-300, 그리고 ultro gel을 사용한 gel filtration에서는 하나의 분획을 나타내 상호분리가 불가능 하였으며 정제도와 분리도에서 가장 뛰어난 gel column을 이용한 FPLC도 toxin A와 C를 상호분리할 수 없었다. 그러나 CM-column을 이용한 FPLC에서는 enterotoxin A는 pH 6.8에서 그리고 enterotoxin C는 pH 8.6에서 각각 분리되었으며, immunodiffusion test 결과 enterotoxin A의 분획에서는 toxin C가 전혀 검출되지 않았고 enterotoxin C의 분획에서도 toxin A가 검출되지 않았다. 용출방법에 있어서는 CM-column을 이용한 FPLC에서 pH-stepwise법이나 pH-gradient법으로 enterotoxin A와 C type을 쉽게 동시에 분리할 수 있었다.

• Toxicological Research
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• 제17권
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• pp.97-104
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• 2001

Three types of proteases (MEF-1, MEF-2 and MEF-3) were purified from the egg cases of Ten-odera sinensis using ammonium sulfate fractionation, gel filtration on Bio-Gel P-60 and affinity chromatography on DEAE Affi-Gel blue gel. The proteases were assessed homogeneous by SDS-polyacrylamide gel electrophoresis and have molecular weight of 31,500, 32,900 and 35,600 Da, respectively. The N-terminal regions of the primary structure were compared and they were found to be different each other. MEFs readily digested the $A\alpha$ - and B$\beta$-chains of fibrinogen and more slowly the ${\gamma}$-chain. The action of the enzymes resulted in extensive hydrolysis of fibrinogen and fibrin, releasing a variety of fibrinopeptides. MEF-1 was inactivated by Cu$^{2+}$ and Zn$^{2+}$ and inhibited by PMSF and chymostatin. MEF-2 was inhibited by PMSF, TLCK. soybean trypsin inhibitor. MEF-3 was only inhibited by PMSF and chymostatin. Antiplasmin was not sensitive to MEF-1 but antithrombin III inhibited the enzymatic activity qf MEF-1. MEF-2 specifically bound to anti plasmin Among the chromogenic protease substrates, the most sensitive one to the hydrolysis of MEFs was benzoyl-Phe-Val-Arg-p-nitroanilide with maximal activity at pH 7.0 and 3$0^{\circ}C$. MEF-1 preferentially cleaved the oxidized B-chain of insulin between Leu15 and Tyr16. In contrast, MEF-2 specifically cleaved the peptide bond between Arg23 and Gly24. D-dimer concentrations increased on incubation of cross-linked fibrin with MEF-1, indicating the enzyme has a strong fibrinolytic activity.ity.

• Parasites, Hosts and Diseases
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• 제30권3호
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• pp.183-190
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• 1992

한국 내에서 사육 공급하는 실험실용 흰쥐를 실험적으로 면역억제하여 Pneumocystis carinii (Pc)를 발현시키고, 이를 순수하게 모아서 전기영동을 이용한 핵형을 분석하였다. Field Inversion Gel Electrophoresis와 Contour Clamped Homogeneous Electric Field Electrophoresis를 사용하여 분리한 염색체 밴드는 Sprague Dawley(SD) 와 Fisher(F) 계 횐쥐 모두에서 15개 씩 이었다. 크기는 수D 횐쥐의 경우 270~684kb, 횐쥐에서 얻은 표본에서 273~713kb에 있었다. 이 중에서 SD 된쥐에서 얻은 것은 283kb의 염색체가, 횐쥐의 표본은 273 kb의 염색체가 특히 강하게 염색되어 두 개 이상의 같은 크기 분자가 중칩된 것으로 보인다. 그러므로 전체 염색체는 최소한 16개이며 각 염색체의 크기로 계산된 염색체 내 전체 유전자의 크기는 $7{\times}10^6{\;}bp$의 수준에 있다. F흰쥐에서 유래한 Pc는 전 염색체 분자가 공유하는 반복 염기서열을 가지며, 448kb 염색체가 rRNA의 유전자를 갖고 있었다. 그러나 SD횐쥐의 Pc표본에서는 어느 염색체 분자에서도 반복 염기서열과 rRNA유전자를 확인하지 못하였다. 두 개의 휜쥐 계통 군은 각각 2년간 같은 핵형의 Pc를 유지하였다. (이 연구는 한국과학재단 1990년도 일반과제 연구비 지원에 의하여 수행되었음)