• 분석과학
• /
• 제27권5호
• /
• pp.248-253
• /
• 2014

이 연구는 Mn과 Pb의 노출이 면역체계에 미치는 영향을 파악하고자 하였다. 연구대상자는 남성 근로자 42 명으로, 대상자 중 13명은 사무직 근로자(실험군 I), 21 명은 제조업 사업장 근로자(실험군 II), 8명은 용접 작업자(실험군 III)였다. 대상자의 혈액 중 Mn과 Pb 농도는 실험군별로 유의한 차이를 보였다. 실험군 I 대상자의 CD19+와 total lymphocytes 농도는 기타의 실험군 대상자에서보다 유의하게 높았으나 다른 T lymphocytes subpopulation의 농도는 차이가 없었다. Mn과 Pb 농도는 T lymphocytes subpopulation과 음의 상관관계를 보였으나, Mn은 CD4+CD45RO+와 자연살해세포를 제외한 T lymphocytes subpopulation과 유의한 음의 상관관계를 보였다. Pb 농도는 단지 total lymphocytes 농도와 유의한 음의 상관관계를 보였다. 이 연구에서 Mn과 Pb의 직업적인 노출은 세포성면역계에 영향을 미칠 수 있음을 제시하였다.

• 한국재료학회지
• /
• 제15권9호
• /
• pp.598-603
• /
• 2005

To develope new lead-free solders with the melting temperature close to that of Sn-37Pb$(183^{\circ}C)$, Sn-0.7Cu-5Pb-1Ga, Sn-0.7Cu-5Pb-1Ag, Sn-0.7Cu-5Pb-5Bi-1Ag, and Sn-0.7Cu-SBi-1Ag alloys were composed by adding low-netting elements such as Ga, Bi, Pb, and Ag to Sn-0.7Cu. Then the melting temperatures, microstructures, wettability, and adhesion properties of these alloys were evaluated. DSC analysis showed that the melting temperature of Sn-0.7Cu-SPb-1Ga was $211^{\circ}C$, and those of other alloys was in the range of $192\~200^{\circ}C$. Microstructures of these alloys after heat-treatment at $150^{\circ}C$ for 24 hrs were basically composed of coarsely- grown $\beta-Sn$ grains, and $Cu_6Sn_5$ and $Ag_3Sn$ intermetallic precipitates. Sn-0.7Cu-5Pb-1Ga and Sn-0.7Cu-5Pb-5Bi-1Ag showed excellent wettability, while Sn-0.7Cu-5Bi-1Ag and Sn-0.7Cu-5Pb-5Bi-1Ag revealed good adhesion strength with the Cu substrates. Among 4 alloys, Sn-0.7Cu-5Pb-5Bi-1Ag with the lowest melting temperature $(192^{\circ}C)$ and relatively excellent wettability and adhesion strength was suggested to be the best candidate solder to replace Sn-37Pb.

• Electronic Materials Letters
• /
• 제14권6호
• /
• pp.700-711
• /
• 2018

CdS synthesized by the chemical bath method at $70^{\circ}C$, has been used as an electron transport layer in the planar structure of the perovskite solar cells. A two-step spin process produced a mixed halide perovskite of $CH_3NH_3PbI_{3-x}Cl_x$ and a mixture of $PbCl_2$ and $PbI_2$ was deposited on CdS, followed by a sub-sequential reaction with MAI ($CH_3NH_3I$). The added $PbCl_2$ to $PbI_2$ in the first spin-step affected the structure, orientation, and shape of lead halides, which varied depending on the content of Cl. A small amount of Cl enhanced the surface morphology and the preferred orientation of $PbI_2$, which led to large and uniform grains of perovskite thin films. In contrast, the high content of Cl produces a new phase PbICl in addition to $PbI_2$, which leads to the small and highly uniform grains of perovskites. An improved surface coverage of perovskite films with the large and uniform grains maximized the performance of perovskite solar cells at 0.1 molar ratio of $PbCl_2$ to $PbI_2$. The depth profiling of elements in both lead halide films and mixed halide perovskite films were measured by Rutherford backscattering spectroscopy, revealing the distribution of chlorine along with the thickness, and providing the basis for the mechanism for enhanced preferred orientation of lead halide and the microstructure of perovskites.

• 한국세라믹학회지
• /
• 제25권4호
• /
• pp.321-328
• /
• 1988

The sintering phenomena, electrical resistivity, dielectric and piezoelectric properties of lead titanate ceramics modified by the partial substitution of La for Pb and Mn for Ti, (Pb1-1.5xLax)(Ti1-yMny)O3 ceramics, have been investigated. In (Pb1-1.5xLax)(Ti1-yMny)O3 system, with increasing lanthanum content, the realtive bulk density increased, but the Curie point and tetragonality (c/a) decreased. The tetragonal-to-cubic phase transition boundary existed in the range of 0.20

• 한국세라믹학회지
• /
• 제33권4호
• /
• pp.399-404
• /
• 1996

Hydrothemal synthesis of PbTiO3 has been investigated. A comprehensive thermodynamic model for heteroge-nous reacting solid-aquous system has been used to predict the optimum condition for the synthesis. Synthesis were performed using lead acetate trihydrate as Pb source crystalline TiO2 as Ti source and KOH as minerali-zer. The synthesis has been examined at low temperature (16$0^{\circ}C$) Phase pure perovskite PbTiO3 has been obtained at high pH(above 0.5 mol KOH). The morphology of PbTiO3 was acicular shape. It has been found sible for a distortion in the c direction. The water is gradully released on annealing the powder to 40$0^{\circ}C$ and the normal crystallographic properties are restored.

• 한국전기전자재료학회논문지
• /
• 제21권6호
• /
• pp.552-555
• /
• 2008

The purpose of this study was to find a best condition of fabricating lead zirconate thin film by sol-gel method, especially to find mol ratio and post annealing temperature. Lead zirconate thin film was made by spin coating method. The ratios of Pb and Zr of precursors were 1:0.8, 1:1.0, and 1:1.2. Annealing temperature of films were $600^{\circ}C$, $700^{\circ}C$, and $800^{\circ}C$ for 1 minute. Crystal structure was observed from XRD and antiferroelectricity was observed from hysteresis curves. The optimum mol ratio of Pb:Zr is 1:0.8 and annealing temperature is $800^{\circ}C$.

• 한국표면공학회지
• /
• 제4권1호
• /
• pp.16-23
• /
• 1971

In this study , fluoborte solution consisting of lead fluoborate, tin fluoborate and cupric acetate was used. By addition of small amount of Cu+= ion to the solution, the Cu content of deposition layer was almost controlled less than 5%. The amount of Cu in deposition layer was almost constant without any influence of Pb++ & Sn++ in the solution, and the amount of Pb was increased by the increase of total concentration of Pb++ +Sn++ in the solution, and the amount of Pb was increased by the increase of total concentration of Pb++ +Sn++ in the solution . Agitation of plating solution & low current density result in the increase of Cu content. Analyzing of microscopic structures and etching tests of the deposited alloy, it was believed that the alloy had a lamellar structure consisting of copper rich lamellar and lead rich layer.

• 대한한방내과학회지
• /
• 제22권2호
• /
• pp.193-198
• /
• 2001

This study was designed to investigate the effects of Korean Lycii Fructus water extract in Pb-administered rats. The Pb exposed rats were given 100 ppm and 200 ppm in the distilled water. Sixty male Sprague-Dawley rats weighing between 90 and 110g were blocked into 6 groups according to body weight. The control group was fed a normal diet, without lead. The experimental groups, which was fed a normal diet plus 100 ppm and 200 ppm lead, and one group received a normal diet plus Lycii Fructus water extracts. The results: the Food intake, the weight gain, and the kidney weight content in the cadmium added groups were lower than those in the Lycii Fructus water extracts group. The contents of Pb in the kidneys of the rats were determined by using ICP(lnductively Coupled Plasma Spectrophotometer). The accumulation of lead in the kidney was lower in the Lycii Fructus water extracts group. The Plasma levels of renin activity was higher in the lead administration groups, as compared with the Lycii Fructus water extracts. Plasma levels of aldosterone activity was higher in the lead administration group, as compared with Lycii Fructus water extracts. These results suggest that Lycii Fructus water extracts has a lowering effects on the accumulation of pb on kidney and it is believed that the Lycii Fructus water extracts have some protective effects on lead-induced nephrotoxicity in rats, but the mechanism of these effects was obscure.

• 생명과학회지
• /
• 제15권6호
• /
• pp.979-986
• /
• 2005

수유기 동안 납의 투여는 급격한 체중의 변화를 유발하여 3주령 및 11주령 쥐의 경우 납을 투여한 군이 대조군에 비해 각각 50% 및 26% 체중 감소를 보였으나 뇌의 무게에는 유의적 변화를 관찰 할 수 없었다. 납 투여는 뇌 지방산 조성 변화에 큰 영향을 주지 않았지만 특히 AA와 DPAn-6와 같은 고도의 불포화 지방산 함량의 증가를 유발하였다. Motor ac-tivity 실험에서 납 투여군의 경우 대조군에 비하여 주어진 시간 내에서 움직이는 시간과 움직인 거리가 긴 것으로 보아 운동 활동성이 큰 것으로 여겨지나 두 군 간에 유의적 차이는 없었다. Elevated plus maze 실험에서 실험 1일째의 경우 open arm에 머무른 시간에는 유의적 차이가 없었으나 2일째에는 두 군에서 현저히 open arm에 머무른 시간이 감소하였으며 납 투여군의 경우 대조군에 비하여 머무른 시간이 감소하는 경향이었으나 통계적 유의성은 없었다. Open arm에 들어가는 횟수를 관찰한 결과, 실험 1일째의 경우 open arm에 들어가는 횟수가 납 투여군에서 유의적으로 적었고 2일째에는 두 군에서 모두 open arm에 들어가는 횟수가 감소하였으며 대조군에 비해 납을 투여한 쥐의 경우가 유의적으로 낮은 횟수로 open arm에 들어갔음을 관찰 할 수 있었다. 이상의 결과로부터 수유기 동안의 납 투여는 성숙 동물의 불안감을 증가시키는 효과를 나타내었다.

• 한국대기환경학회지
• /
• 제2권3호
• /
• pp.11-18
• /
• 1986

In order to evaluate the state of the environmental pollution by vehicle exhaust in Seoul area the correlation between lead in air and leaves of roadside trees has been investigated during August in 1985. The dust in the atmosphere was collected by high volume air sampler to measure the concentration of lead. On the other hand, lead as a pollution indicator was extracted from the leaves of roadside trees (Ginkgo biloba, Salix pseudo/lasiogyne, platanus occidentalis) by conventional method and their concentrations were determined. The following results were obtained : 1. Lead concentrations in the leaves of roadside trees varied with trees, for example, the average concentrations of lead in each of the leaves of Ginkgo biloba, Salix pseudo/lasiogyne and Platanus occidentalis were 20.66 ppm, 9.37 ppm, and 10.58 ppm, respectively. 2. The dust sampled along heavily traveled highways showed that lead content tended to increase with traffic volume. 3. The correlation coefficients between lead correlation in air and leaves of Gingo biloba, Salix pseudo/lasiogyne, and Platanus orientalis were 0.80, 0.85, and 0.87, respectively.