• KSBB Journal
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• 제15권5호
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• pp.444-451
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• 2000

Nonliving methanotrophic biomass was used as biosorbent to remove lead which is one of representative pollutants in metal-bearing wastewater. Solution pH, maximum uptake, biosorbent dose and ionic strength were considered as major factors for adsorption experiments. The optimum pH range for lead removal was increased 3.8∼11.0 for methanotrophic biomass compared to biosorbent-free control, pH of 8.4∼11.2. Removal efficiency of lead by methanotrophic biomass was pH dependent, but less sensitive than that of control. In isotherm experiments with 0.2g biosorbent/L at initial solution pH 5.0, methanotrophic biomass took up lead from aqueous solutions to the extent of 1085 mg/g biomass. Removal amount of lead increased with an increase of biomass dose. According to biomass dose for initial 1000 mg Pb/L at initial pH 5.0, the optimum amount of biomass for maximum lead removal per unit methanotrophic biomass was 0.2 g biomass/L. As a result of scanning electron microscope (SEM) micrographs equipped with energy dispersive spectroscopy (EDS), lead removal by methanotrophic biomass seemed to be through adsorptions on the surface of methanotrophic biomass and exopolymers around the biomass. EDS spectra confirmed that lead adsorption appeared on the biomass and exopolymers that may be effective to lead removal comparing before and after contact with lead. Removal efficiency of lead was slightly affected by ionic strength up to 2.0 M of NaCl and NaNO$_3$respectively.

• Clinical and Experimental Pediatrics
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• 제57권8호
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• pp.345-350
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• 2014

Iron deficiency affects approximately one-third of the world's population, occurring most frequently in children aged 6 months to 3 years. Mechanisms of iron absorption are similar to those of other divalent metals, particularly manganese, lead, and cadmium, and a diet deficient in iron can lead to excess absorption of manganese, lead, and cadmium. Iron deficiency may lead to cognitive impairments resulting from the deficiency itself or from increased metal concentrations caused by the deficiency. Iron deficiency combined with increased manganese or lead concentrations may further affect neurodevelopment. We recently showed that blood manganese and lead concentrations are elevated among iron-deficient infants. Increased blood manganese and lead levels are likely associated with prolonged breast-feeding, which is also a risk factor for iron deficiency. Thus, babies who are breast-fed for prolonged periods should be given plain, iron-fortified cereals or other good sources of dietary iron.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.437-443
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• 2024

The development and testing of inspection equipment is necessary for the safe deployment of advanced nuclear reactors. One proposed advanced reactor design is Westinghouse's lead-cooled fast reactor (LFR). In this paper, the process of achieving adequate wetting for an ultrasonic under-lead viewing system is discussed and results presented. Such a device would be used for inspection in the molten lead core during reactor outages. Wider tests into the wetting of various materials in molten lead at microscale were performed using electron microscopy. The possible mechanisms and kinetics for materials wetting in lead, particularly stainless steel and nickel, are proposed and discussed.

• 수산해양기술연구
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• 제34권1호
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• pp.96-103
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• 1998

Lead-acid battery is being most widely used with secondary battery because of its low price, and long life cycles. But According to using for a long time, its voltage, capacity, and recovery ability is decreased gradually. Therefore there are many papers about improving the property of a lead-acid battery. One of them is to slow down sulfation due to formation of inner PbSO sub(4) by adding inhibitor to electrolyte, however it was not well known what is inhibitor's composition and its role acting on both cathodic and anodic electrode because of its know-how of every country and companies. The purpose of this paper is to study about improvement of property of lead-acid battery by adding one of the inhibitor to H sub(2) SO sub(4) electrolyte.

• 한국초전도ㆍ저온공학회논문지
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• 제1권2호
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• pp.37-42
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• 1999

The stability of high-temperature superconducting current leads for cryogenic devices are investigated. By assuming full transition from superconducting state to normal state at a transition temperature, the HTS current at a transition temperature, the HTS current lead shows bifurcation phenomenon. There is a bifurcation shape-factor, HTS leads have three steady state. Below the bifurcation shape-factor, the superconducting current lead is unconditionally stable, because there exists only one steady-factor HTS current lead is conditionally stable depending on the shape and intensity of disturbance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1402-1403
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• 2006

The sulphation is main deterioration of lead-acid batter, then there were many kinds of attempts to improve these problems and one of them is to add additives to the electrolyte. In this study some mixed additives such as silicate & boric acid and silicate & phosphoric acid were added to 38% $H_{2}SO_{4}$ electrolyte of lead acid battery to improve electrochemical properties of corrosion resistance, etc. of anode and cathode of lead acid battery.

• Journal of Preventive Medicine and Public Health
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• 제24권4호
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• pp.516-530
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• 1991

일상생활을 통한 연섭취로 인한 고혈압 발생 가능성 및 이때 연이 혈압에 영향을 미칠 수 있는 기전을 밝히기 위한 연구의 일환으로 환자 대조군 연구를 실시하였다. 대상자로서 울산 및 그 인근지역의 직업적 연폭로 과거력이 없는 남자 근로자 중 고혈압 환자 72명, 대조군 69명을 선택하였다. 혈중 연과 혈장레닌활성도(Plasma renin activity, PRA)를 측정하였으며 동시에 흡연유무, 음주유무, 고혈압 가족력 유무를 확인하고 body mass index(BMI), 혈청 소디움, 포타시움, 이온화 칼슘, 크레아티닌 및 총 콜레스테롤을 측정하였다. 고혈압군의 혈중 연농도는 $19.8{\pm}5.5{\mu}g/dl$로서 대조군의 $12.5{\pm}4.7{\mu}g/dl$에 비해 유의하게 높았고(p<0.01) 또한 혈중 연의 고혈압발생에 대한 교차비(odds ratio)가 1.38로서 역시 유의하였다(p<0.01). PRA나 In(PRA)가 고혈압군과 대조군 사이에 유의한 차이가 없었으나 고혈압군에서 혈중 연농도가 증가함에 따라 PRA도 어느정도 증가하는 양상을 보였고(p<0.1), In(PHA)를 종속변수로 하는 중회귀분석을 실시하였을 때 혈중 연농도(회귀계수 ; 0.037)가 10% 수준에서 유의하였다. 본 연구를 통해 볼 때, 지금까지 알려진 정상치 범위 이내의 혈중 연과 고혈압 발생간의 인과 관계에 대해 계속 연구해 볼 필요성을 느끼며 이때 PRA의 변화가 작용 기전의 일부에 관여할 가능성이 있을 것으로 추측된다.

• 한국토양환경학회지
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• 제4권1호
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• pp.3-11
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• 1999

4종류의 서로 다른 납 처리시설 주변토양과 인위적으로 납을 오염시킨 토양에서 토양 내에 존재하는 주요 양이온과 토양 질량 대 EDTA 용액부피 비 및 납과 EDTA의 정량비(stoichiometric ratio)가 EDTA를 사용한 납 추출에 미치는 영향을 연구하였다. 납 오염토양으로부터의 납 추출은 EDTA용액 부피 대 토양 질량 비를 3$m\ell$/g까지 감소시켜도 영향을 받지 않았으며 단지 용액 내에 존재하는 EDTA의 몰수에 의존하는 것으로 밝혀졌다. 본 연구결과에 의하면 각각의 토양에 대한 납 추출효과는 서로 다른 독립적인 경향을 보였으며 납 광산시설 주변토양을 제외하고는 다량의 EDTA가 유입되면 모든 납이 추출되었다. 이러한 결과는 Fe, Cu. Zn, Al과 같은 토양 내에 존재하는 주요 양이온이 EDTA 의 ligand site에 반응하기 위하여 Pb와 경쟁하기 때문인 것으로 추정되어진다. 납 추출을 위한 EDTA의 도입은 여러 음이온 용해도의 증가를 동반하여 토양내 금속의 용해도를 증가하는 결과를 나타내었으며 용해되어진 금속의 양은 유입된 EDTA 몰수에 최대 20배에 이루는 것으로 나타났다. 납오염된 토양에서의 EDTA를 이용한 납 추출은 토양내의 주요 양이온, 납의 종류(species)및 납의 결합 형태와 위치에 의하여 영향을 받는 것으로 나타났으며 이러한 영향이 복합적으로 작용할 때에는 EDTA의 납 추출효과가 현저히 감소하는 것으로 밝혀졌다.

• Journal of Radiation Protection and Research
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• 제4권1호
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• pp.14-20
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• 1979

고(高)에너지 방사선(放射線) 치료(治療)에 있어서 정상조직(正常組織)의 완전차폐(完全遮蔽)를 위하여 $5{\sim}8cm$ 납두께의 부정형(不定形) 차폐(遮蔽)벽돌을 제작(製作)해야하는 난점(難點)이 있었다. 저자(著者)들은 납 30.0%, 주석 11.5% 비스므스 48.5%, 카드미늄 10.0%를 사중(四重) 공정결합(共晶結合)시켜 밀도(密度)가 $9.8g/cm^3$ 용융온도(熔融溫度)가 $68^{\circ}C$인 저용융(低熔融) 차폐물질(遮蔽物質)을 개발(開發)하여 이를 Lead Y라고 명명(名命)하였다. 제작(製作)된 Lead Y Block을 $68^{\circ}C$에서 용융(熔融)시켜 보호(保護)해야할 중요(重要)한 장기(臟器)의 형태(形態)대로 제작(製作)된 styrofoam 음형(陰形)에 부어서 차폐효과(遮蔽效果)가 큰 차폐(遮蔽)벽돌을 쉽고 안전(安全)하게 제작(製作)할 수 있었고 납보다 더 단단하고 재현성(再現性)이 크며 저렴(低廉)한 가격(價格)으로 구입(購入)이 가능(可能)하므로 방사선(放射線) 치료효과(治療效果)에 큰 도움을 줄 수 있었다.

• Biomolecules & Therapeutics
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• 제3권4호
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• pp.288-293
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• 1995

In the present study, we tested whether lead intoxication could change the thiamine content and the activity of transketolase, one of thiamine-dependent enzymes, in the brain of rats. It was also tested whether administration of excessive thiamine can reverse the toxic manifestation of lead in the lead intoxicated rats. Four groups of Wistar rats were prepared: 1) control group, 2) lead treated group, 3) lead plus thiamine treated group and 4) thiamine deficient group. Each group of animals was divided into three subgroups based on ages: 3, 7 and 16 weeks. Lead concentration, thiamine content and the activity of transketolase in three different brain regions, i.e.,, telencephalon, brain stem and cerebellum, were measured in each group. Lead concentrations in brain regions of the lead treated group were significantly higher than those of the control group, and those of the lead plus thiamine treated group were significantly decreased from those of the lead treated group. Thiamine contents in the brain regions of the lead treated group were significantly lower than those of the control group, and those of the lead plus thiamine treated group were recovered back to those of the control group. Activities of transketolase in the brain regions of the lead treated group and the thiamine deficient group were significantly lower than those of the control group, while those of the lead plus thiamine treated group were higher than the lead treated group. The results from the present study suggest that neurotoxicity following lead intoxication in rats may be mediated, at least in part, through the changes of thiamine status and consequently thiamine-dependent biochemical reactions such as theactivity of transketolase.