• Resources Recycling
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• v.1 no.1
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• pp.58-68
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• 1992

A process development for direct synthesis of high pure ZnO powders from zinc-bearing waste was investigated. This waste contains a 55% of zinc and it was extracted by the sulfuric acid(leaching). After removal of iron ion by precipitation from the zinc solution, the purification through a solvent extraction by the use of D2EHPA as an extractant was carried out. Then, loaded zinc in organic solution was stripped and precipitated simultaneously using a precipitant such as oxalic acid. Then, loaded zinc in organic solution was stripped and precipitated simulataneously using a precipitant such as oxalic acid. The synthesized $ZnC_2O_4$ powders by the precipitation stripping method was calcined to obtain more than 99.9% of ZnO powders. The effect of sulfuric acid concentration, leaching time, pulp density on the extraction of zinc was studied and the optimum conditions for the solvent extraction were obtained through the investigation of purification of zinc solution. The size, morphology and size distribution of synthesized $ZnC_2O_4$ powders were studied in terms of oxalic acid concentration, temperature, surfactant added, precipitation time, etc.

• Molecular & Cellular Toxicology
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• v.3 no.4
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• pp.292-298
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• 2007

Zinc plays indispensable roles in metabolism, including cell growth, apoptosis, proliferation and differentiation. Kidneys are target organs for various regulators of mineral metabolism, and play a key role in zinc balance. To investigate the zinc uptake efficiency, we examined the zinc uptake and accumulation level in vivo and in vitro study. Plasma zinc concentration was peaked out at 1 hr after oral zinc administration. The renal zinc level was peaked out at 12 hr after oral zinc administration, and it was the highest in 40 mg/kg Zn-Asp administrated group in comparison with other groups. In addition, the m-RNA expression level of zinc transporter-1 (ZnT-1), zinc transporter-2 (ZnT-2) and high-affinity L-aspartate transporter (EAAT-3) in Zn-Asp administered group were increased compared with control groups and $ZnSO_4$ group. In order to investigate the intracellular zinc uptake mechanism, we performed the in vitro study by using human embryonic kidney cell line, HEK 293. Intracellular zinc level was peaked out at 3 hr after zinc treatment. In the same way, the mRNA expression level of ZnT-1 and EAAT-3 were increased compared with control group. This study showed that Zn-Asp is effective the zinc uptake into the kidney by increasing the zinc transporter expression.

• Membrane and Water Treatment
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• v.9 no.5
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• pp.301-307
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• 2018

In this research work, synthesis of sugarcane bagasse/zinc aluminium biocomposite and apple peel/zinc aluminium biocomposite and their application for removal of Reactive Red-241 and Acid Orange-7, respectively, was studied using various parameters. At pH 2 the sorption was the highest for both dyes. The trend showed that the dye sorption declined by decreasing the biocomposite dose and enhanced by increasing the dye concentration and temperature. Equilibrium was achieved at 60 minutes for Reactive Red-241 onto sugarcane bagasse/zinc aluminium biocomposite and 90 minutes for Acid Orange-7 onto apple peel/zinc aluminium biocomposite.The research data was good fitted to pseudo-2nd-order kinetic model and Langmuir isotherm. FT-IR analysis was used to confirm the biosorption of the selected dyes at the surface of biosorbent through various binding sites. Surface morphology modification of both biocomposites before and after biosorption was inspected through SEM. Crystallinity of biocomposite was examined through XRD analysis. It was implied that sugarcane bagasse/ zinc aluminium biocomposite and apple peel/ zinc aluminium biocomposite are good adsorbents for dyes elimination from aqueous solutions.

• Journal of the Korean Dietetic Association
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• v.7 no.3
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• pp.258-266
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• 2001

The purpose of this study was to investigate the effect of dietary zinc on the carbohydrate metabolism and the serum content of magnesium and chromium in rats fed normal diet. Animals were divided into three groups by different dietary zinc levels which were low(15ppm), normal(30ppm) or high(60ppm). Serum glucose and Insulin concentrations were assessed by the glucose method and the radio immuno assay respectively. Serum zinc. magnesium and chromium contents were measured by Indectively Coupled Plasma(ICP). Results of the study were as follows : 1. Feed intake in a zinc deficiency group was significantly higher than that in other group, but the weight gain in high zinc diet group was significantly lower than in other groups. 2. There were no significant differences in liver, kidney and spleen weight. 3. Serum glucose, insulin and zinc concentrations were not significantly different among different dietary zinc groups, However serum magnesium and chromium concentrations were significantly decreased as the level of dietary zinc was increased.

• Korean Journal of Community Nutrition
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• v.5 no.3
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• pp.484-492
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• 2000

In an attempt to figure out the relationship between zinc status and taste acuity of old and young women, dietary zinc intake, urinary zinc excretion, and taste acuity were determined for 118 women. Zinc intake was measured by 2-day food records and food frequency method. Urinary zinc excretion was measured from urine samples collected for twenty four hours. Body fat, lean body mass (LBM), and total body water were measured by bio-impedence. Average dietary zinc intake by food record was 4.15$\pm$1.33mg (=35% if Korean RDA) for the old women and 5.41$\pm$2.76mg (=25% of RDA) for young women. When zinc intake was measured by a frequency method, the average intakes of the old and young women were 3.5$\pm$1.7mg 4.5$\pm$1.9mg, respectively. It appears that dietary zinc intake of young women was significantly higher than that of the old women. Average urinary zinc excretion of the subjects was 0.27$\pm$0.16mg in the elderly and 0.24$\pm$0.13mg in young women, which indicated a marginal zinc status. However, zinc status was not significantly different between old and young women. Correlation analysis indicated that zinc intake and urinary zinc excretion were positively related to BMI and LBM in young women. The old women (m=49) showed significantly higher taste detection thresholds than young subjects (n=47) for both sweet and salty tastes. Recognition thresholds for sodium chloride and sucrose were not significantly different between old and young women. The lower the taste thresholds for salty taste, the higher the average dietary zinc intake. However, taste perception concentration was not related to the urinary zinc excretion level.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.9 no.1
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• pp.14-22
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• 2006

Purpose: To identify factors that influence serum zinc concentrations in children with acute gastroenteritis. Methods: Thirty-two children under 5 years of age (15 boys and 17 girls) were selected randomly among those who visited to an pediatric emergency room of Ehwa Womans University Mokdong Hospital with acute gastroenteritis from May to August 2005. This study estimated the association between serum zinc concentrations and clinical, biochemical variables in patients with acute gastroenteritis. Results: Serum zinc concentration was lower in febrile patients than afebrile patients with acute gastroenteritis ($67.5{\pm}25.3$ vs $85.5{\pm}14.2$, p<0.05). It also was lower in patients with positive C-reactive protein (CRP) than those with negative CRP ($63.9{\pm}25.4$vs $86.7{\pm}13.8$, p<0.05). Serum zinc concentration was negatively correlated (r=-0.494, p<0.05) with CRP concentration, whereas positively correlated with hematocrit (r=0.370, p<0.05), total protein (r=0.474, p<0.05), and albumin (r=0.636, p<0.05). Twelve patients (37.5%) showed very low serum zinc concentration (< $70{\mu}g/dL$) without clinical symptoms of deficiency or growth retardation. Frequency of febrile illness or positive CRP is significantly greater in group with zinc < $70{\mu}g/dL$ than the group with zinc ${\geq}70{\mu}g/dL$ (91.7% vs 55%, p<0.05; 91.7% vs 40%, p<0.05, respectively). Conclusion: In patients with acute gastroenteritis, serum zinc concentration was influenced by various factors such as fever, CRP, and biochemical factors. For evaluating zinc status in the body. factors.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.177-182
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• 1999

The electrolyte was brought into contact with air and potassium carbonate concentration was measured with various contact time in order to check the effect of carbon dioxide in the air on zinc-air cell. The relationship between potassium carbonate concentration in electrolyte and battery capacity was also studied. The potassium carbonate concentration increased due to carbon dioxide absorption with increasing contact time with air, but the cell capacity linearly decreased with increasing potassium carbonate concentration in the electrolyte. The rate of carbon dioxide absorption was mainly affected by the pore size of hydrophobic membrane. Our study showed that adapting the pore of hydrophobic membrane decreased the loss of cell discharge performance due to the presence of carbon dioxide or water vapor in the atmosphere.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.25 no.1
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• pp.28-36
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• 2014

Objectives : The goal of this study was to examine the association between zinc and lead level and symptoms of attention-deficit hyperactivity disorder (ADHD) among Korean children. Methods : A total of 89 clinic-referred children participated in the study (ADHD group=45, control group=44). The participants were 5-15 years old, and were mainly from urban areas of Seoul, Korea. ADHD was diagnosed using the Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version. We excluded children with a comorbid psychiatric disorder, medical illness requiring medication, or a prior history of taking ADHD medication. In order to evaluate the severity of ADHD symptoms, parents' Korean ADHD Rating Scale (K-ARS) was used. The ADHD diagnostic system (ADS) was used for evaluation of the severity of inattention and impulsivity. All participants completed the intelligence test and hair mineral analysis. Multiple regression analysis was used to examine the effect of hair zinc and lead levels on the K-ARS and ADS. We measured the predictive ability of the zinc and lead levels using logistic regression analysis. Results : The lead level explained the score for omission errors, commission errors, and response time SD in visual ADS in the ADHD group (adjusted $R^2$=.243, p<.01, adjusted $R^2$=.362, p<.01, and adjusted $R^2$=.275, p<.01), the score for omission errors of auditory ADS in ADHD group (adjusted $R^2$=.407, p<.01) and the entire group (adjusted $R^2$=.292, p<.01). Zinc was significantly explanatory for the K-ARS scores for the entire group (adjusted $R^2$=.248, p<.001) and the ADHD group (adjusted $R^2$=.247, p<.05). Conclusion : These findings suggest a possible role of zinc and lead in ADHD. Lead concentration in hair samples affected the ADS scores, and this was more prominent in children with ADHD. Children with ADHD had a lower zinc concentration in their hair, and the zinc concentration in hair showed negative correlation with the K-ARS score.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.846-851
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• 1998

An experimental research on the preparation of zinc oxide fine particles in w/o emulsions was conducted. Precipitation solutions were zinc nitrate aqueous solutions with hexamethylenetetramine(HMTA) as precipitant. The precipitation solutions formed stable w/o emulsions with kerosine in the presence of Span 80. Homogeneous precipitation reaction occurred in the w/o emulsion after the resultant w/o emulsion was heated above the decomposition temperature of HMTA and zinc oxide particles were precipitated. In some case, zinc oxide particles of bi-modal distribution were obtained. However, zinc oxide fine particles of narrow particle size distribution could be obtained, even when the initial zinc concentration of precipitation solution and the conversion to zinc oxide are both higher that those in bulk homogeneous precipitation.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.191-195
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• 2003

Zinc acetate has been proposed and used to evaluate ionic zinc as a means to reduce reactor radiation buildup at several nuclear plants. Thermodynamic analysis of the aqueous zinc system using reliable data shows that the stability of the hydrolyzed zinc species increases with pH and temperature. Adsorption kinetics and isotherm studies were carried out to investigate the mixed resin performance of the zinc adsorption. The equilibrium isotherms of the zinc adsorption onto nuclear grade resin indicate that the data correlate well with the Langmuir model and that the adsorption is physical in nature. The maximum capacity according to the Langrnuir model is about 0.6meq/g for an initial zinc concentration of 100ppm at $50^{\circ}C$. The use of natural zinc could result in the generation of a $^{65}Zn$ activity with about $500{\mu}Ci/mL$ of resin after 12 months of operation.