• Clean Technology
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• v.21 no.3
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• pp.178-183
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• 2015

Lead molybdate (PbMoO₄) oxides were successfully synthesized using a conventional hydrothermal method and a microwave-assisted hydrothermal method. They were characterized by XRD, DRS, BET, Raman, SEM and PL. We also investigated the photocatalytic activity of these materials for the decomposition of Rhodamine B under UV-light irradiation. From XRD and Raman results, well-crystallized PbMoO₄ crystals have been successfully synthesized regardless of preparation method and had 42~59 nm particle size. The PbMoO₄ catalysts prepared using microwave-assisted process had the similar particle size and enhanced the photocatalytic activity when compared to that prepared by hydrothermal method. The PbMoO₄ catalysts prepared under the irradiation of microwave for 75 min showed the highest photocatalytic activity. The PL peaks appears at about 530 nm at all catalysts and it was also shown that the excitonic PL signal is proportional to the photocatalytic activity for the decomposition of Rhodamine B.

• Journal of the Korean Chemical Society
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• v.38 no.1
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• pp.41-49
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• 1994

Exchange reaction mechanisms of the Pb(II) ion for the complexes between Pb(II) ion and nitrogen oxygen donor macrocyclic ligands, such as 1,13-diaza-3,4 : $1011-dibenzo-59-dioxacyclohexa-decane(NtnOtnH_4)$, 1,15-diaza-3,4 : $1213-dibenzo-5811-trioxacycloheptadecane(NenOdienH_4)$, and 1,15-diaza-3,4 : $1213-dibenzo-5811-trioxacyclooctadecane(NtnOdienH_4)$, were studied by $^{207}Pb-NMR$ spectroscopy in N,N'-dimethylformamide(DMF) solutions. The associative-dissociative mechanism dominated in $NtnOtnH_4-Pb(II)$ and $NtnOdienH_4-Pb(II)$ system. For $NenOdienH_4-Pb(II)$ system, the bimolecular exchange mechanism prevailed below $-5^{\circ}C$, and both bimolecular exchange and associative-dissociative mechanism dominated above $+5^{\circ}C.$ The order of activation energies for dissociation was $NtnOdienH_4\;<\;NtnOtnH_4\;<\;NenOdienH_4$ which was reverse to the order of stabilities.

• Journal of the East Asian Society of Dietary Life
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• v.11 no.4
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• pp.259-267
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• 2001

This study was to investigate the effect of selenium on hepatic antioxidative defense system and oxidative damage in lead-administered rats. Male Sprague-Dawley rats weighing 140$\pm$5g were divided into one normal group(Se, 0 ppm) and three lead groups according to dietary levels of selenium supplementation: Pb0(Se, 0 ppm), PbS(Se, 0.5 ppm), and PbSS(Se, 1.0 ppm). All experimental groups were fed the experimental diet ad libitum for 4 weeks, and lead groups fed one containing 2,000 ppm lead acetate. Liver superoxide dismutase(SOD) activities in Pb0 group increased compared with other experimental groups. Liver gluthathione peroxidase(GSH-px) activities in Pb0 group decreased compared with normal group, but those of PbS and PbSS groups significantly increased compared with Pb0 group. Glutathione S-transferase(GST) activities decreased in Pb0 group and not significantly different from PbS and PbSS groups compared with normal group. Reduced glutathione(GSH) contents and GSH/GSSG of liver in Pb0 group were lower than those of other groups. Liver vitamin E contents in Pb0 group were about 50% of the normal group, but those of PbSS and PbS increased more than Pb0 group. Liver damage in electron microphotography process decreased in RER, showed an increase in Iysosome and also an increase in swelling of mitochondria. and ordered as follows : PbSS. PbS. and Pb0. It was concluded that high levels of dietary selenium had protective effects on peroxidative damage of hepatic cell accompanied with increased antioxidative defense system in lead-administered rats.

• Korean Journal of Materials Research
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• v.4 no.4
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• pp.472-476
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• 1994

Phase transformation of PbO-precursor prepared from $Pb(NO_{3})_{2}$ by precipitation technique was observed by TG-DTA, XRD, FT-IR, and Raman spectral analysis. PbO-precursor was derived from an aqueous solution of $Pb(NO_{3})_{2}$ at $45^{\circ}C$ and pH of 9.0. The precipitate showed it to be the mixture of hydrous lead oxynitrate and lead hydroxynitrate. With increasing heat-treatment temperature ranging up to $560^{\circ}C$, the precursor changed to $3Pb(NO_{3})_{2}$ . 7Pb0, $Pb(NO_{3})_{2}$. 5Pb0 and PbO(litharge), in turn. Finally, it transformed to massicot form of PbO above $560^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.24 no.4
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• pp.397-403
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• 1987

Pb(Zr0.52Ti0.48)O3 powders were prepared by hydrothermal synthesis. Using soluble salts such as Pb(NO3)2, TiCl4 and ZrOCl2$.$8H2O and oxide such as PbO and TiO2 as starting materials, PZT powder was hydrothermally synthesized at the temperature range between 150$^{\circ}C$ and 200$^{\circ}C$. The result showed that reactivity by alkali was decreased in the sequence of Pb(NO3)2, TiCl4, ZrOCl2, PbO, TiO2 and ZrO2. Using the first three soluble salts, PZT powder was synthesiged at 150$^{\circ}C$ for 1hr. In PbO-TiCl4-ZrOCl2 system, PZT powder was synthesized at 150$^{\circ}C$ for 8rs. In Pb(NO3)2-TiO2-ZrOCl2 system, PZT powder was synthesized at 150$^{\circ}C$ for 16hrs, in PbO-TiO2-ZrOCl2 system, the powder was synthesized at 200$^{\circ}C$ for 8hrs.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.141-148
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• 1999

High quality pure and Nb-doped $PbWO_{4}$ Single Crystal were grown from a 50 %~50 % mixture of Lead oxide (PbO) and Tungsten oxide $(WO_{3})$ by Czochralski method in Iridium crucible. The stoichiometric deviation correspond to the selective loss of the crystal constituents is found to be responsible for the yellowish coloration of $PbWO_{4}$. Through the X-ray powder diffraction experiment, we have investigated the lattice constant variations of each $PbWO_{4}$ crystals. We also present information on their photoluminescence (PL), optical absoption properties and Raman spectra. The temperature dependence of PL intensity and FWHM (Full Width Half Maximum) were measured in the temperature range 10 K~300 K. One observes a slight temperature dependence in the low temperature region and PL intensity decreases over 200 K by thermal quenching. The activation energy, Huang-Rhys coupling constant and inhomogenious brodenning acquired from their temperature dependence.

• Journal of Nutrition and Health
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• v.38 no.5
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• pp.380-385
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• 2005

This study was designed to investigate the effects of mulberry leaf powder supplementation on lead (Pb) status and mineral (Ca, Fe, Cu and Zn) content in Pb-administered rats for 4 weeks. Thirty two male rats were divided into 4 groups: a control, Pb, Pb5M (500 ppm $Pb + 5\%$ mulberry leaf powder), and Pb10M (500 ppm $Pb + 10\%$ mulberry leaf powder). There were no significant differences in food intake and initial body weight among groups. Mulberry leaf powder treatments showed significant decreases in food efficiency ratio and body weight gain. But FER of $Pb5M\%$ and Pb10M were significantly increases than that of Pb group. The levels of serum aspartate transaminase (AST) and creatinine were decreased by mulberry leaf powder treatment. Minerals content of liver and kidney were significantly decreased in the Pb groups than that of control group. Whereas, fecal minerals content were significantly increased in the Pb5M and Pb10M than those of control group. Pb content of serum, liver and kidney was significantly increased in the Pb group than those of control group. However, by mulberry leaf powder administration (Pb5M and Pb10M), Pb level of serum, liver and kidney were lowered than that of Pb group. And fecal Pb excretion was significantly increased in the Pb5M and Pb10M than that of Pb group. These results showed mulberry leaves were effective for lowing Pb accumulation in serum, organs, which may have potential to prevent Pb toxicity.

• Journal of Nutrition and Health
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• v.20 no.4
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• pp.225-236
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• 1987

This study was performed to investigate the effects of lead poisoning and different levels of dietary lipid on lead and lipid metabolism in the rats. Forty eight male weanling rats of Sprague-Dawley strain weighing 73.1$\pm$11.1g were blocked into 6 groups according to body weight. Dietary lipid were given at the lev딘 of 5, 20 and 40% of total caloric intake and lead were either administered or not. The results obtained are summerized as follows ; 1) Food intake, weight gain, F.E.R. liver and epididymal. fat pad weights, weight and length of bone, hematocrit and hemoglobin content in Pb-adminstered groups were lower than these in Pb-free groups. 2) Plasma lipid and cholesterol levels were tended to be higher in Pb-administered groups than in Pb-free groups, while liver lipid and cholesterol levels were tended to be lower in Pb-adminstered groups. 3) Fecal dry matter excretion was tended to be higher in Pb-adminstered groups than in Pb-free groups, and were increased with increasing dietary lipid level. Daily fecal excretions of lipid and cholesterol were higher in high lipid groups than in low lipid groups and these levels were even higher in the animals exposed to Pb than in Pb-free groups. 4) Pb contents in blood, liver, kidney and bone were significantly higher in Pb administered groups than in Pb-free groups. Pb levels of blood, liver and bone did not show any significant difference among groups with different levels of dietary lipid, but Pb concentration in kidney of Pb-adminstered groups increased with increasing dietary lipid level.

• Applied Chemistry for Engineering
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• v.26 no.6
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• pp.714-718
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• 2015

Both lead molybdate ($PbMoO_4$) and chromium substituted lead molybdate ($PbMo_{1-x}Cr_xO_4$) were successfully synthesized using a conventional hydrothermal method and characterized by XRD, DRS, Raman, SEM and PL. We also investigated the photocatalytic activity of these materials for the decomposition of rhodamine B under UV-visible irradiation. The XRD and Raman results revealed the successful synthesis of well-crystallized $PbMoO_4$ crystals with the diameter of 51-59 nm, regardless of the addition of chromium ion. The DRS spectra of $PbMo_{1-x}Cr_xO_4$ catalysts showed new intensive absorption bands in the visible region. The $PbMoO_4$ catalysts showed the lowest photocatalytic activity and the activity increased with an increase of chromium substitution amounts under visible irradiation. PL peaks appeared at about 540-580 nm for all catalysts and excitonic PL signals were proportional to the photocatalytic activity for the decomposition of rhodamine B.

• Journal of the Microelectronics and Packaging Society
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• v.1 no.2
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• pp.125-134
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• 1994

저항범위가 다른 두종류의 Ru계 후막저항계(1Kohm/sq. 100kohm/sq.)를 선택하여 도전상의 상전이 기구를 반응조건을 변화시켜 연구하였다. 저저항체의 경우 도전상으로는 RuO2였으며 700-100$0^{\circ}C$에서 1시간 반응한 경우 반응온도에 따른 구성상의 변화는 없었다 반응온도 90$0^{\circ}C$에서 반응시간이 경과함에 따라 도전상은 RuO2가 Glass의 구성성분인 Pb와 반응하여 Rb2(Ru1.69 Pb0.31)O6.5로 변하고 시간이 36시간 경과한 후에는 도전상이 Pb4Al2Si2O10인 결정으로 둘러 쌓이는 반응인 peritectic reaction이 일어났다. 고전항체의 경 우 도전상으로는 Pb2(Ru1.69 Pb0.31)O6.5로 변하고 시간이 36시간 경과한 후에는 더전상이 Pb4Al2Si2O10인 결정으로 둘러쌓이는 반응인 peritectic reaction 이 일어났다. 고저항체의 경 우 도전상으로는 Pb2(Ru1.69 Pb0.31)O6.5인 pyrochrole 상이였다. 100$0^{\circ}C$에서 1시간 반응시킬 경 우 도전상이 RuO2로 변하였다. 반응온도를 90$0^{\circ}C$로 하고 반응시간을 변화시키면 도전상인 Pb2(Ru1.69 Pb0.31)O6.5가 (Ru1.69Pb0.31)O4x로 변하면서 공존하였다.