• 전기화학회지
• /
• 제3권4호
• /
• pp.204-210
• /
• 2000

용융아연 도금 강판 제조시 용융아연 도금 bath중의 알루미늄 농도를 조절하는 것은 매우 중요하다 본 연구의 목적은 용융아연 도금욕 중 알루미늄 농도를 신속하게 측정할 수 있는 센서 개발을 위한 기초 data를 제공하는 것이다. $CaF_2$고체전해질과 3가지 종류의 참조극을 사용하여 $460^{\circ}C\~500^{\circ}C$의 순수한 용융아연 bath에서 불소포텐샬을 측정하였다. 용융 아연 중 알루미늄의 농도를 측정하기 위하여 다음과 같은 불소 이온 농담전지 센서를 구성하였다. $$(-)W|Zn-Al,\;AlF_3|CaF_2|Bi,BiF_3|W(+)$$ 알루미늄의 농도가 $0.984wt\%$이하인 Zn-Al bath의 온도를 $460\pm10^{\circ}C$로 유지하고 상기의 알루미늄 농도 센서를 이용하여 기전력을 측정하였다. 측정된 기전력 값으로부터 최소 자승 회귀분석법을 이용하여, 다음과 같은 알루미늄 농도와 기전력과의 관계식을 얻었다. $$E/mV=56.795log[\%Al]+1881.7\;R=0.9704$$,$$0.026wt\%{\leq}[\%Al]{\leq}0.984wt\%$$

• 자원리싸이클링
• /
• 제23권1호
• /
• pp.58-63
• /
• 2014

전기로 제강분진(EAFD)으로부터 환원배소에 의해 회수한 조산화 아연 내에는 다양한 종류의 비등점이 낮은 물질이 존재한다. 따라서 일반적으로 산화배소를 통한 정제과정을 통해 염화물 형태로 존재하는 물질들을 기화시켜 고순도의 기능성 산화아연을 생산하게 된다. 따라서 본 연구에서는 조산화 아연의 산화배소 특성을 체계적으로 규명하여 대량생산공정에 적용할 때의 효율성을 극대화하고자 하였다. 조산화 아연을 적절한 방법을 통해 직경 1-3 mm, 10 mm의 펠렛을 제조하여, 각 시편을 분말시편과 함께 수직 관상로에서 로타리 킬른의 실조업을 묘사하여 산화분위기에서 $600{\sim}1200^{\circ}C$ 온도영역까지 $20^{\circ}C/hr$ 승온속도로 가열하면서 체재시간을 유지하였다. 실험결과 펠렛의 크기에 따른 기화속도의 변화가 $950^{\circ}C$ 이상의 온도에서는 현저히 증가함을 알 수 있었다. 회수된 시편은 ICP-OES, XRF장비를 통하여 성분분석을 실시한 결과 Zn의 농도는 비례적으로 증가함을 알 수 있었으며, Cl 등의 불순물의 농도도 현저히 감소하였다. XRD 분석결과 온도가 증가할수록 염화물 피크는 관찰되지 않았으며, 본 산화배소실험을 통하여 98%이상의 고순도 산화아연을 얻을 수 있었다.

• Nutrition Research and Practice
• /
• 제14권2호
• /
• pp.117-126
• /
• 2020

BACKGROUND/OBJECTIVES: Vitamin D and zinc are recognized for their roles in immune-modulation, and their deficiencies are suggested to be important risk factors for childhood infections. This study, therefore, undertook to assess the occurrence of infections in rural Indian schoolchildren, subsequent to daily supplementation with vitamin D-calcium or zinc for 6 months. SUBJECTS/METHODS: This was a randomized, double-blind, placebo-controlled trial in apparently healthy 6-12 year-old rural Indian children, recruited to 3 study arms: vitamin D arm (1,000 IU D3 - 500 mg calcium, n = 135), zinc arm (10 mg, n = 150) and placebo arm (n = 150). The infection status was assessed using a validated questionnaire, and the biochemical parameters of serum 25(OH)D and serum zinc were measured by ELISA and colorimetry, respectively. The primary outcome variable was occurrence of infections (upper respiratory and total infections). RESULTS: Serum 25(OH)D concentration in the vitamin D arm improved significantly by 34%, from 59.7 ± 10.9 nmol/L to 80 ± 23.3 nmol/L (P < 0.0001), but no improvement was observed for serum zinc concentration. While there was significant increase in the percentage of children reporting no or mild upper respiratory tract infections (URTI) and total infections (TI) in all three groups, improvements in the supplemented groups were similar to the placebo group. However, the vitamin D arm reported lower URTI and TI status in the vitamin D sufficient versus insufficient children. Also, URTI and TI status were found to be significantly (P < 0.0001) lower in children with improved 25(OH)D versus unchanged 25(OH)D. CONCLUSIONS: Vitamin D-calcium supplementation helped to improve the vitamin D status but exerts no effect on the occurrence of infections when compared to the placebo group. Improvement in the serum 25(OH)D concentrations and attainment of vitamin D sufficiency may exert a beneficial effect on the infection status and needs to be investigated further. To evaluate the efficacy of zinc supplementation, higher dosages need to be administered in future studies.

• 아시안잔디학회지
• /
• 제10권4호
• /
• pp.315-329
• /
• 1996

The changes of growth and protein synthesis pattern by aluminum (Al), cadmium (Cd), zinc (Zn) treatments were studied in Cyanobacterium synechocystis sp. PCC 6803. When exposed to Al from 5ppm to 3oppm, synechocystis grows normally. But more than that retard the growth of algae notably. The 0.05ppm Cd additions had no effect on the growth of algae. 0.1, 0.2, and 0.5ppm Cd inhibited growth. Under 1 and 2ppm Cd stress, growth was greatly diminished. Zn had dual effects. The growth of algae in media containing 5ppm was stimulated. As concentration increases more than l5ppm, growth inbition increases. Under 25ppm Zn stress, growth was greatly diminished. According to logistic theory, r and K values of each heavy metal-treated groups were estimated. Correlation analysis of r and K values with metal concentration shows that there is negative correlation between K and concentration in Cd and Zn treatments. Critical concentration which shows lethal or sublethal effect was estimated by t-test of each r and K value. The cells cultured in 10, 20, 30, 40 and 5oppm of Al, 1 and 2ppm of Cd, and 10, 15, 20, 25 and 30ppm of Zn for 4 days was used for protein analysis. Analysis of protein synthesis with SDS-PACE showed alterations of protein synthesis pattern. The synthesis of protein about 220kD increased markedly. In this study, it showed that resistance mechanism against Al, Cd, and Zn is K selection and that metal stress induced the change of protein synthesis in Cyanobacterium synechocystis sp. PCC 6803.Key words:Cyanobacterium synechocystis sp. FCC 6803, Heavy metals, Aluminum, Cadmiutm Zinc, Crowth, Frotein synthesis.

• Journal of Nutrition and Health
• /
• 제38권7호
• /
• pp.578-585
• /
• 2005

Maternal zinc deficiency is relatively common worldwide, but its consequences for pregnancy outcome are not established. The purpose of this study was to examine the effect of zinc status in the second trimester on pregnancy outcome. Subjects were 248 pregnant Korean women (25-28 wk gestation). Cord blood was collected from subgroup of 69 women and pregnancy outcome data were obtained from 185 babies. Anthropometry measurement, dietary intake, and biochemical characteristics of pregnancy and cord serum substances were measured. The subjects were divided into quartiles on the basis of maternal serum Zn concentration; $ZnQ_1$ (< 25 percentile), $ZnQ_2$ ($26\~50$ percentile), $ZnQ_3$ ($51\~75$ percentile), and $ZnQ_4$ ($76\~100$ percentile). Zn groups were compared in terms of various maternal factors, concentrations of cord serum substances, and pregnancy outcome. Maternal serum Zn concentration was $118.4\;{\pm}\;35.5\;{\mu}g/dl$ as mean. Intake of Zn was lower than Korean RDA. The rate of Zn deficiency among all subjects was $8.5\%$. Maternal serum Zn levels belonged to normal range. Cord serum Zn level was about $154.7\%$ of maternal serum level. Intakes of energy, calcium, iron, folic acid, and riboflavin did not meet the Korean RDA for pregnant women by gestational age. The mean birth weight of neonates is 3083 $\pm$ 697 g, of whom $9.1\%$ were of low birth weight (< 2,500 g). Maternal serum Zn level was positively correlated with pre-pregnancy weight, pre-pregnancy body mass index, and vitamin C intake (p < 0.05). $ZnQ_1$ group had significantly lower maternal serum iron concentration and higher cord serum cholesterol than those in other groups. Maternal serum Zn level, cord serum Zn level, and dietary Zn intake were no related to the pregnancy outcome. The birth weight had a correlation with the maternal hemoglobin and albumin concentration. In conclusion, at this study, we could not find the association with maternal Zn status in 2nd trimester and pregnancy outcome.

• 한국산업보건학회지
• /
• 제17권1호
• /
• pp.43-52
• /
• 2007

This study was designed to investigate the difference of airborne lead concentration by type of lead industries and type of lead exposure and to evaluate their association with lead biomarkers of lead workers in 11 lead using industries. Total of 182 lead workers (male: 167, female: 15) from 11 lead industries were participated for this study from March, 2004 to August, 2005. Airborne lead concentration were measured by representative personal sampling of workers in each unit workplace and applied same concentration value to the workers in the same unit workplace who did not measure their airborne lead with personal air sampling. Tibia lead, blood lead, zinc protoporphyrin in whole blood, ${\delta}$-aminolevulinic acid in urine, hemoglobin and hematocrit were selected as study variables of indices of lead exposure. Information about type of lead exposure (fume or non-fume other), age, work duration, smoking & drinking habit were also collected. Significant differences were seen in the means of zinc protoporphyrin, blood lead and tibia lead in lead workers by different airborne lead concentration in workplace. While blood lead and tibia lead in lead workers were significantly higher in secondary smelting than other types of lead industries, zinc protoporphyrin, ${\delta}$-aminolevulinic acid in urine and airborne lead concentration were significantly higher in litharge manufacturing. While the mean blood lead was significantly higher in the lead workers working in fume type unit workplace than those of non-fume lead workers, the mean airborne lead concentration of fume workers was significantly lower than non-fume lead workers. In the multiple regression analysis of airborne lead concentration and the type of lead exposure on tibia lead and lead exposure indices after adjustment of related covariates, airborne lead concentration was statistically significantly associated with blood lead and tibia lead, but the type of lead exposure was only associated with blood lead. To verify the causal association of airborne lead concentration on blood lead and tibia lead, further studies are needed.

• 산업보건소식
• /
• 제48호
• /
• pp.9-18
• /
• 1987

The results of this study which had been investigated to analyse heavy metal levels and to compare lead, cadmium, copper and zinc concentration in urine of children who lived around the industrial area and the agricultural area. Samples were collected and analyzed from September to December 1986 from 7-9 years old children living in Seoul (4 7 cases), lri ( 64 cases) industrial area and Chinan (56 cases) agricultural area. The summarized results were as follows: 1) The concentrations of lead were Seoul 28.7 $\pm$17.7 ug/l, lri 25.3 $\pm$7.5 ug/l and Chinan 19.3 $\pm$5.2 ug/l 2) The concentrations of cadmium were Seoul 1.5 $\pm$0.8 ug/l, Iri 1.4 $\pm$0.5 ug/l and chinan 0.9 $\pm$0.3 ug/l 3) The concentrations of copper were Seoul 12.8 $\pm$7.0 ug/l, Iri 10.5 $\pm$8.4 ug/l and Chinan 10.0 $\pm$4.5 ug/l 4) The concentrations of zinc were Seoul 383 $\pm$279 ug/l, Iri 329 $\pm$133 ug/l and Chinan 267 $\pm$181 ug/l 5) In lead, cadmium and zinc concentration of children, there were statistical difference between the industrial area and the agricultural area 6) There were no indicated significantly levels by the Sex

• Carbon letters
• /
• 제9권2호
• /
• pp.108-114
• /
• 2008

We have demonstrated the feasibility of using electrospinning method to fabricate long and continuous composite nanofiber sheets of polyacrylonitrile (PAN) incorporated with zinc oxide (ZnO). Such PAN/ZnO composite nanofiber sheets represent an important step toward utilizing carbon nanofibers (CNFs) as materials to achieve remarkably enhanced physico-chemical properties. In an attempt to derive these advantages, we have used a variety of techniques such as field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high resolution X-ray diffraction (HR-XRD) to obtain quantitative data on the materials. The CNFs produced are in the diameter range of 100 to 350 nm after carbonization at $1000^{\circ}C$. Electrical conductivity of the random CNFs was increased by increasing the concentration of ZnO. A dramatic improvement in porosity and specific surface area of the CNFs was a clear evidence of the novelty of the method used. This study indicated that the optimal ZnO concentration of 3 wt% is enough to produce CNFs having enhanced electrical and physico-chemical properties.

• 한국물환경학회지
• /
• 제23권5호
• /
• pp.723-730
• /
• 2007

This study was conducted to develop a combined method for remediating a Chlorinated Aliphatic Hydrocarbons (CAHs) mixtures-contaminated aquifer. The process is consist of two processes. A chemical process (1st) using natural zinc ores for reducing higher concentrations of CAH mixtures to the level at which biological process is feasible; and A biological process (2nd) using aerobic cometabolism for treating lower concentration of CAH mixtures (less than 1 mg/L). Natural zinc ore showed relatively high transformation capacity, average dehalogenation percentage, and the best economic efficiency in previously our study. To evaluate the feasibility of the process, we operated two columns in series (that is, chemical and biological columns). In the first column filled with natural zinc ore and sand, CAH mixtures were effectively transformed with more than 95% efficiency, the efficiency depends on the Empty Bed Contact Time (EBCT) and the mass of zinc ore packed. Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD) analysis were performed to make sure whether natural zinc ore played an key role in the dechlorination of the CAH mixtures. The characteristics of zinc metal surface changed after exposure to CAHs due to oxidation of $Zn^0$ to $Zn^{2+}$. In the biological column injecting propane, DO and effluent of the chemical column, only 1,1,1-TCA was cometabolically transformed. Consequently, the combined process would be effective to remediate an aquifer contaminated with high concentrations of CAH mixtures.

• 폴리머
• /
• 제38권5호
• /
• pp.580-587
• /
• 2014

7 wt% alginate를 용액상태로 제조한 후 필름 메이커를 이용하여 필름 형태로 만든 후 3, 5 wt%의 $ZnCl_2$, $CaCl_2$ 수용액에 필름을 고화시킨 후 수세하여 상온에서 건조시켜 zinc calcium alginate 복합필름을 제조하였다. 필름의 특성을 조사하기 위하여 항균성, 수용해도, 팽윤도 및 점도, SEM, EDS 분석 등을 측정하였다. Zinc calcium alginate 복합필름은 $ZnCl_2$, $CaCl_2$ 함량이 증가할수록 용해저항성은 증가하였으며, 항균성 시험 결과, zinc alginate 필름뿐만 아니라 calcium alginate 필름에서도 두 균주(포도상구균, 대장균) 모두 우수한 항균력을 확인하였으며, 본 연구를 통해 복합필름의 물성개선의 가능성을 확인하였다.