• The Korean Journal of Ecology
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• v.21 no.3
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• pp.179-186
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• 1998

Effects of lead(Pb) and calcium(Ca) on growth responses, accumulation of heavy metals and nitrogen fixation activities of Melilotus suaveolens seedlings were quantitatively analyzed during growing period. Pb contents of the root treated with 30, 100 ppm Pb and 100 ppm Pb added 100 ppm Ca were 54.1, 90.9 and 26.1 folds higher than that of the control, respectively, at pH 4.2 in 28th days, and heavy metal content of plant increased with increasing of pH and Pb concentration. The melilot plant was classified as a Pb accumulator by higher accumulation of Pb in shoot than that of root. Pb treatments resulted in inhibiton of height and chlorophyll contet, and Ca treatment increased height and chlorophyll content insignificantly at pH 4.2 in 28 days. The plant biomass reduced 49, 60 and 54% at pH 4.2 and 47,53 and 50% at pH 6.5, respectively, by 30, 100 ppm Pb and 100 ppm Pb added 100 ppm Ca treatment. Specific nitrogen fixation of nodules reduced 68.4% and 46.6% by 100 ppm Pb treatment and 3.7% and 24.9% by 100 ppm Pb added 100 ppm Ca at pH 4.2 and pH 6.5, respectively, so Ca inhibited significantly Pb activity and toxicity in acdic pH. Nodule formation were reduced to 33, 33 and 50% at pH 4.2 and 50, 33 and 38% at pH 6.5 by 30, 100 ppm Pb and 100 ppm Pb added 100 ppm Ca, respectively.

• Toxicological Research
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• v.25 no.4
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• pp.175-180
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• 2009

Lead (Pb) is a ubiquitously occurring environmental heavy metal which is widely used in industry and human life. Possibly due to a global industrial expansion, recent studies have revealed the prevalent human exposure to Pb and increased risk of Pb toxicity. Once ingested by human, 95% of absorbed Pb is accumulated into erythrocytes and erythrocytes are known to be a prime target for Pb toxicity. Most of the studies were however, focused on $Pb^{2+}$ whereas the effects of $Pb^{4+}$, another major form of Pb on erythrocytes are poorly understood yet. In this study, we investigated and compared the effects of $Pb^{4+}$, $Pb^{2+}$ and other heavy metals on procoagulant activation of erythrocytes, an important factor for the participation of erythrocytes in thrombotic events in an effort to address the cardiovascular toxicity of $Pb^{4+}$. Freshly isolated erythrocytes from human were incubated with $Pb^{4+}$, $Pb^{2+}$, $Cd^{2+}$ and $Ag^+$ and the exposure of phosphatidylserine (PS), key marker for procoagulant activation was measured using flow cytometry. As a result, while $Cd^{2+}$ and $Ag^+$ did not affect PS exposure, $Pb^{4+}$ and $Pb^{2+}$ induced significantly PS exposure in a dose-dependent manner. Of a particular note, $Pb^{4+}$ induced PS exposure with a similar potency with $Pb^{2+}$. PS bearing microvesicle (MV), another important contributor to procoagulant activation was also generated by $Pb^{4+}$. These PS exposure and MV generation by $Pb^{4+}$ were well in line with the shape change of erythrocyte from normal discocytes to MV shedding echinocytes following $Pb^{4+}$ treatment. Meanwhile, nonspecific hemolysis was not observed suggesting the specificity of $Pb^{4+}$-induced PS exposure and MV generation. These results indicated that $Pb^{4+}$ could induce procoagulant activation of erythrocytes through PS exposure and MV generation, suggesting that $Pb^{4+}$ exposure might ultimately lead to increased thrombotic events.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.207-214
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• 2016

This study determined the effect of Lespedeza Caneata extract on the livers and kidneys of lead-administered mice. The experimental groups were divided into a normal group, Pb 4W group, Pb-LC 4W group, Pb 8W group, and Pb-LC 8W group. The normal group was supplied single distilled water, and the pb group was provided distilled water in which lead acetate was dissolved at 1,000 ppm. The Pb-LC group was provided with lead as drinking water, and the Lespedeza Caneata was orally medicated at a concentration of 500 mg/kg daily. AST, ALT, and BUN enzyme activities and histological experiments on the livers and kidneys resulted in the following conclusions. AST, ALT, and BUN activities increased in the experimental group compared to the normal group and decreased more in the Pb-LC group than the pb group during the same period. The histological results reveal that portions of the livers and kidneys were deformed in the Pb 4W group, and most of the Pb 8W group experienced necrosis and deformation. pb-LC4W and Pb-LC 8W groups experienced less deformation than the Pb 4W and Pb 8W groups. During the same period, the Pb-LC group experienced less histological changes than the Pb group. These results suggest that Lespedeza Caneata extract may have some protective effect on hepatic tissue and renal tissue damage with lead-administered in mice.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.4
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• pp.107-114
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• 2018

In this exploration, the nuclear magnetic resonance of the $^{207}Pb$ nucleus in $PbWO_4:Mn^{2+}$ and $PbWO_4:Dy^{3+}$ Single Crystals using FT-NMR spectrometer is investigated. The line width of the resonance line for the $^{207}Pb$ nucleus decreases as temperature increases due to motional narrowing. The chemical shift of $^{207}Pb$ NMR spectra also increases as temperature decreases for both crystals. The spinlattice relaxation times $T_1$ of $^{39}K$ nucleus were calculated as a function of temperature (180 K~400 K). The $T_1$ of $^{207}Pb$ nucleus decreases as temperature increases. The dominant relaxation mechanism at the studied temperature range can be deduced as the Raman process, which is the coupling between lattice vibrations and the nuclear spins. This deduction is substantiated by the fact that the nuclear spin-lattice relaxation rate $1/T_1$ of the $^{207}Pb$ nucleus in $PbWO_4:Mn^{2+}$ and $PbWO_4:Dy^{3+}$ single crystal is proportional to $T^2$, or temperature squared. The activation energies for the $^{207}Pb$ nucleus in $PbWO_4:Mn^{2+}$ and $PbWO_4:Dy^{3+}$ single crystals are $E_a=49{\pm}1meV$ and $E_a=47{\pm}2meV$, respectively.

• Journal of Electrochemical Science and Technology
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• v.2 no.2
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• pp.76-84
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• 2011

Potentiostatic oxidation of Pb-1.7%Sb alloy used in the manufacture of grids of lead-acid batteries over the potential range from -1.0V to 2.3V in 5M $H_2SO_4$ in the absence and the presence of 0.4M $H_3PO_4$ and the self-discharge characteristics of the oxide layer formed is studied by electrochemical impedance spectroscopy (EIS). Depending on the potential value, sharp variations in resistance and capacitance of the alloy are recorded during the oxidation and they can be used for identification of the various substances involved in passive layer. Addition of $H_3PO_4$ is found to deteriorate the insulating properties of the passive layer by the retardation of the formation of $PbSO_4$. $H_3PO_4$ completely inhibits the current and impedance fluctuations recorded in $H_3PO_4$-free solutions in the potential range 0.5 V-1.7 V. These fluctuations are attributed to the occurrence of competitive redox processes that involve the formation of $PbSO_4$, $PbOSO_4$, PbO and $PbO_2$ and the repeated formation and breakdown of the passive layer. Self-discharge experiments indicate that the amount of $PbO_2$ formed in the presence of $H_3PO_4$ is lesser than in the $H_3PO_4$-free solutions. The start of transformation of $PbSO_4$ into $PbO_2$ is greatly shortened. $H_3PO_4$ facilitates the diffusion process of soluble species through the passive layer ($PbSO_4$ and basic $PbSO_4$) but impedes the diffusion process through $PbO_2$.

• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.307-312
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• 2016

Lead molybdate ($PbMoO_4$) was successfully synthesized using a facile surfactant-assisted hydrothermal process and characterized by XRD, Raman, TEM, PL, BET and DRS. 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 $PbMoO_4$ crystals were successfully synthesized with the particle size of 52-69 nm. $PbMoO_4$ catalysts prepared in the presence of cetyltrimethyl ammonium bromide (CTAB) enhanced the photocatalytic activity compared to that of using P-25 and pure $PbMoO_4$ catalysts. The maximum photocatalytic activity of $PbMoO_4$ catalyst were observed when preparing it in pH 9 solution. The The PL peak at about 540 nm were observed for all catalysts and the excitonic PL signal increased proportionally with respect to the photocatalytic activity of Rhodamine B.

• Journal of the Korean Chemical Society
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• v.31 no.2
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• pp.162-167
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• 1987

Four component $Ag_2S$-PbS-$PbHAsO_4-Cu_2S$ and three component $Ag_2S$-PbS-$PbHAsO_4$ electrodes have been prepared and evaluated for the direct measurement of monohydrogen arsenate. The 3.0 : 0.5 : 1.0 : 0.25 (mole ratio, $Ag_2S$:PbS:$PbHAsO_4:Cu_2S$) composition is superior in terms of potentiometric response, stability, rapidity of response and reproducibility. Testing was done over the concentration range $10^{-1}$~$10^{-4}M\;HA_SO_4^{2-}$in 0.1F NH4Ac-NH4OH buffer solution at pH 8.50 with constant ionic strength. Interfering ions were $CN^-,\;I^-,\;S^{-2}$ and $Cl^-$.

• Korean Journal of Animal Reproduction
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• v.25 no.2
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• pp.139-145
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• 2001

This study was performed to elucidate the patho-physiology of lead acetate-poisoned rats after consecutive oral administrations of the lead. The changes in feed and water intake, gains of body weight, blood pictures and mineral compositions of several organs were observed to measure the effects of lead acetate-poisoning. 1. Compared with control group, every experimental group of which 1,000, 2,000, or 4,000 ppm/kg of lead acetate was administered displayed a gradual decrease in feed intake in dose-dependent manners. 2. After 1,000, 2,000 or 4,000 ppm/kg of lead acetate administration, water intake seemed to decrease in every experimental group in dose-dependent manners. 3. After 1,000, 2,000 or 4,000 ppm/kg of lead acetate administration, body weight decreased in every experimental group in dose-dependent manners. 4. After 1000, 2,000 or 4,000 ppm/kg of lead acetate administration, the PLT values and numbers of RBC and WBC significantly increased after lead acetate administration, but the values of Hb and PCV were lower than those of control group's. 5. After 2,000 or 4,000 ppm/kg of lead acetate administration, the levels of Pb, Mn, Fe, Pb and Zn in the livers were lowered, but the levels of Pb, Mn, Fe, Pb and Zn in the kidneys.

• Bulletin of the Korean Chemical Society
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• v.17 no.4
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• pp.324-330
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• 1996

We examined the formal oxidation states of Pb and Cu in the Pb2CuO4 slab of Pb2Sr2ACu3O8(A=Y1-xCaxor Nd1-xSrx) and their possible changes by oxygen incorporation in the Cu layer of the slab by performing tight-binding band electronic structure calculations on the Pb2CuO4+δ slab. Our results show that the most likely oxidation state of Pb is +2 and that of Cu is +1 for the Pb2CuO4 slab prior to oxidation. With small δ values, the oxygen incorporation occurs by the formation of such chain fragments as in YBa2Cu3O7-y along the a+b axis. The four-coordinate Cu atoms in the chain fragments are in the +3 oxidation states. For values of δ larger than 0.5, however, an additional oxygen (Oad) goes to the site along the b axis to form short Pb-Oad distances oxidizing Pb2+ to Pb4+. This change in the Pb oxidation state leads to the suppression of superconductivity due to the decrease of holes in the CuO2 layer.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.454-462
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• 2011

A study on the adsorption characteristics of Pb(II) and Cr(III) cations onto C-methylcalix[4]resorcinarene (CMCR) has been conducted. CMCR was produced by one step synthesis from resorcinol, acetaldehyde, and HCl. Most parameters in batch system confirm that CMCR is a good adsorbent for Pb(II) and Cr(III). Cr(III) uptake was bigger than that of Pb(II), but Cr(III) adsorption rate was slower than Pb(II). The adsorption kinetic of Pb(II) and Cr(III) adsorptions in batch followed pseudo $2^{nd}$ order kinetics model, but the kinetic of Pb(II) adsorption in fixed bed column system followed first order model. Desorption studies to recover the adsorbed Pb(II) was performed sequentially with distilled water and HCl, and the results showed that the adsorption was dominated by chemisorption.