• Clean Technology
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• v.16 no.4
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• pp.292-296
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• 2010

We fabricated quantum dot sensitized solar cells(QDSSC) using PbS as a sensitizer and measured the solar energy conversion efficiency. After growing ZnO nanowires on the substrate by low temperature ammonia solution reaction, PbS QDs were deposited on ZnO nanowires by SILAR(Successive ionic layer adsorption and reaction) method. The morphology and crystallinity of PbS/ZnO nanowires were studied by SEM and XRD. In this study, the maximum conversion efficiency of QDSSC using PbS was 0.075% at one sun, which was lower than that of QDSSC using other sensitizers. The reasons it showed relatively low efficiency are i) the probability of type-I band gap arrangement between ZnO and PbS, ii) disturbance of electron migration by the various-sized PbS band gap, iii) stability dip by the chemical reaction of PbS QDs with electrolyte. To solve these problems, researches about controlling the size distribution of PbS and new type electrolyte would be needed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.5
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• pp.423-429
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• 2001

PbS, CuS and (Pb,Cu)S thin films were chemically deposited on glass from alkaline baths containing lead acetate, copper chloride, thiourea and triethanolamine. The deposition, optical, resistivity and thermal electric properties of these films were studied. PbS thin films showed a hexagonal structure and CuS thin films showed amorphous. The crystalline of (Pb,Cu)S thin films was obtained by heat treatment at 200$\^{C}$ and the deposition ratio of Pb to Cu showed 7:3. The energy gap of PbS, CuS and (Pb,Cu)S thin films were 1.7, 2.1 and 2.4 eV, respectively. Sheet resistance of PbS thin films was less affected on thermal annealing, but hose of (Pb,Cu)S and CuS thin films were more reduced about 3 orders of magnitude. All of those thin films indicated p type semiconductor in temperature ranging 30$\^{C}$ to 150$\^{C}$.

• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.13-16
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• 2000

(PbS)$_{1-x}$ -(CuS)$_{x}$ thin films(x=0, 0.5, 1) were grown on glass substrates by using a chemical bath deposition method. The molecular ratio of Pb to Cu for the PbS-CuS thin films(x=0.5) was measured about 7:3 by using EDX and XRF. The resistivity of non-annealed (PbS)$_{1-x}$ -(CuS)$_{x}$ thin films was about 10 $\Omega$ . cm. However, after annealing, the resistivity of PbS showed a little change, while PbS-CuS and CuS significantly decreased in the range of 0.002 to 0.005$\Omega$.cm. PbS was p-type and CuS was n-type.-type.

• KSBB Journal
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• v.11 no.2
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• pp.173-180
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• 1996

The contamination of the environment by heavy metals results in a serious public health problem due to the toxicity of those pollutants even at low concentrations. Microorganisms may be used to remediate wastewaters contamlialtd with heavy metals. The waste S. cerevisiae is an inexpensive readily available source of biomass for bioremediation of wastewater. S. cerevisiae was investigated for their ability to absorb Pb. The crushed biomass of S. cerevisiae exhibited higher Pb uptake capacity than the living S. cerevisiae and the sterilized S. cerevisiae. At the same metal concentration, metal uptake per unit concentration or adsorbent decreased when the biomass concentration rises. The order of the biosorption capacity of the living S. cerevisiae was Pb>Cu>Cd=Co>Cr. When S. cerevisiae was pretreated with 0.1 M NaOH, Pb uptake was increased by 150 percent and 0.1 M HC1, 0.1 M $H_2S_O4$ solutions were efficient in the desorption of Pb. The sorption equilibrium of Pb ions can be described by the Freundlich and Langmuir models.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.643-651
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• 2006

The Pb-Ag-Bi-S system minerals such as galena-matildite solid solutions, cosalite and heyrovskyite occur in the Nakdong As-Bi deposits. Galena-matildite solid solutions commonly coexisting with native bismuth fill in microfractures of pyrite grains and form irregular shapes. Cosalite forms composite grains including native bismuth, heyrovskyite and Bi-Te-S system minerals in the matrix of quartz vein. Matildite from the Nakdong deposits has an end member composition, $Ag_{1.07-1.11}Bi_{1.12-1.20}S_2$, and an excess concentration of $0.3{\sim}2.4$ mole % $Bi_2S_3$ compared to the stoichiomeoic value. PbS concentrations in $PbS-AgBiS_2$ solid solutions do not exceed 54 mole %. The average chemical composition of cosalite in the study area is $Pb_{1.79}Bi_{2.29}Ag_{0.12}S_5$. Pb is slightly depleted compared to the ideal composition, but the concentrations of Ag and Cu reach as much as 1.47 wt.% and 0.27 wt.%, respectively. Heyrovskyite has the chemical formula of $Pb_{5.01}Ag_{0.26}Bi_{2.70}S_9$ suggesting that there occurs the coupled substitution of $2Bi^{3+}$ for $3Pb^{2+}$ as well as that of $Ag^++Bi^{3+}$ for $2Pb^{2+}$. The genetic condition of Pb-Ag-Bi-S system minerals can be confined to the temperature of $220{\sim}270^{\circ}C$ and the pressure below 200 bars.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.21-24
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• 2000

Properties of thermoelectric power in PbS thin films by chemical bath deposition were investigated The qualified PbS thin film was gained with the amounts of Thiourea($4-8ml/{\ell}$ ), Triethanolamine (1-2ml) and NaOH(l0ml). The molecular ratio of Pb and S was 3 : 7. Satisfied crystallization rate and deposition rate of PbS were greater at $50^{\circ}C$ than at $30^{\circ}C$. The constant of thermoelectric power in PbS was nearly $ 500uv/^{\circ}k$. The PbS thin film was changed from p-type to n-type semiconductor at around $200^{\circ}C$. In case of heat treatment at $300^{\circ}C$, the sample kept the characteristic of p-type semiconductors up to $250^{\circ}C$.

• KSBB Journal
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• v.14 no.5
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• pp.611-615
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• 1999

Biosorption of Pb was evaluated for Sargassum sagamianum. An adsorption equilibrium was reached in about 1 hr. The uptake capacity of Pb was 224.5 mg Pb/G biomass. The adsorption parameters for Pb were determined according to Langmuir and Frueundlich model. With increasing pH, more negative sites are becoming available for adsorption of Pb. When Ca and Mg concentration increases in Pb solution, Pb was selectively adsorbed. The Pb adsorbed by S. sagamianu could be desorbed by desorption process and the efficiency from 0.1M HCl, 0.1M HNO$_3$and 0.1M EDTA was above 95%. S. Sagamianum was reused 6 times and the total uptake was 736.8 mg Pb/g biomass.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.5
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• pp.517-524
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• 1992

In this study, 0.10Pb(SbS11/2TSnS11/2T)OS13T-(0.90-x)PbZrOS13T (0.25 x 0.40) ceramics were fabricated by the atmospheric method. The sintering temperature and time were 1250[$^{\circ}C$] and 2[2hr], respectively. The structureal, dielectric and piezoelectric properties with composition of PbTiOS13T were studied. As the results of XRD ans SEM, the crystal structure of a specimen was rhombohedral, lattice constant and average grain size were decreased with increasing the contents of PbTiOS13T. Relative dielectric constant and Curie temperature were increased with increasing the contents of PbTiOS13T, 0.10PSS-0.40PT-0.50PZ specimen had the highest values of 904 and 265[$^{\circ}C$], respectively. In increasing of PbTiOS13T contents form 25[mol%] to 40[mol%], piezoelectric charge constant and electromechanical coupling factors were increased form 114[pC/N] to 142[pC/N], 17[%] to 24[%] and mechanical quality factor were decreased with increasing the contents of PbTiOS13T. In the 0.10PSS-0.40PT-0.50PZ specimens, those values were 14.2[kV/cm] and 9.43[x10S0-6TC/cmS02T], resectively.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.8
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• pp.858-868
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• 1992

0.085Ba(LaS11/2TNbS11/2T)OS13T-0.915Pb(ZrS1yTTiS11-yT)OS13T (0.45$\leq$y$\leq$0.65) transparent electrooptic ceramics were fabricated by two-stage sintering method. The structural, ferroelectric and electrooptic properties were investigated varying composition and second sintering time. Also the possibility of application to electrooptic device was studied. If we increase the PbZrOS13T contents, dielectric constants were increased and Curie temperature was decreased. In the composition of 0.55[mol] PbZrOS13T, electromechanical coupling factor and piezoelectric charge constant were the highest values of 43[%] and 173x10S0-12T[C/N], respectively. Mechanical quality factors were decreased with the increasing PbZrOS13T contents. Light transmittance was increased with wavelength when measured from 300[nm] to 900[nm], and with PbZrOS13T contents in the range of 0.50[mol]-0.65[mol], and had the highest value of 67[%] in the composition of 0.65[mol] PbZrOS13T. From the results of ferroelectric hysteresis loop and transmitted light intensity with electric field, the specimens with compositions of 0.65,0.60,0.55[mol] PbZrOS13T were applicable to electrooptic memory device and those with compositions of 0.50,0.45[mol] PbZrOS13T were applicable to linear electrooptic device.