• Journal of the Korean Society for Heat Treatment
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• v.33 no.3
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• pp.117-123
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• 2020

Due to high corrosion resistance, Zinc has been widely used in the automobile, shipping or construction industries as a galvanizing material. Zinc is popular as a coating element, but its low mechanical strength impede the expansion of applications as a load-bearing structure. The mechanical strength of Zinc can be increased through zinc based alloy process, but the ductility is significantly reduced. In this study, the mechanical strength and ductility of Zinc-Magnesium alloys with respect to heat treatment hold time was investigated. In order to enhance the mechanical strength of Zinc, a Zinc-Magnesium alloy was fabricated by a melting process. The heat treatment process was performed to improve the ductility of Zinc-Magnesium alloy. The microstructure of the heat-treated alloy specimen was analyzed using SEM. The hardness and compressive strength of the specimen were measured by a micro-hardness tester and a nano-indenter, respectively.

• Molecules and Cells
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• v.43 no.4
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• pp.323-330
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• 2020

Epigenetic events like DNA methylation and histone modification can alter heritable phenotypes. Zinc is required for the activity of various epigenetic enzymes, such as DNA methyltransferases (DNMTs), histone acetyltransferases (HATs), histone deacetylases (HDACs), and histone demethylases, which possess several zinc binding sites. Thus, the dysregulation of zinc homeostasis can lead to epigenetic alterations. Zinc homeostasis is regulated by Zinc Transporters (ZnTs), Zrt- and Irt-like proteins (ZIPs), and the zinc storage protein metallothionein (MT). Recent advances revealed that ZIPs modulate epigenetics. ZIP10 deficiency was found to result in reduced HATs, confirming its involvement in histone acetylation for rigid skin barrier formation. ZIP13 deficiency, which is associated with Spondylocheirodysplastic Ehlers-Danlos syndrome (SCD-EDS), increases DNMT activity, leading to dysgenesis of dermis via improper gene expressions. However, the precise molecular mechanisms remain to be elucidated. Future molecular studies investigating the involvement of zinc and its transporters in epigenetics are warranted.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.163-165
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• 1999

The study was conducted to find the critical concentrations of zinc toxicity and to determine the changes of the contents of free proline and organic acids with treatment of different zinc chloride concentrations during rice germination and seedlings grown for seven days. The concentration of zinc chloride, 140 ppm, inhibited root elongation as much as 46 times compared with the control, and the germination rate was also decreased in all treatments of zinc chloride, showing that the germination rate decreased more with increasing concentrations of zinc chloride. Its rate was only 13% with treatment of 140 ppm zinc chloride. The content of free proline with treatment of zinc chloride, 140 ppm, was highest about 4,873 $\mu$M at 3 days compared with the control. Malic acid concentration with treatment of zinc chloride, 140 ppm, increased to approximately 4 times compared to the control. Citric and succinic acid content were also slightly increased in all treatments of zinc chloride.

• Mycobiology
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• v.43 no.3
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• pp.179-183
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• 2015

Zinc is an essential micronutrient required for many enzymes that play essential roles in a cell. It was estimated that approximately 3% of the total cellular proteins are required for zinc for their functions. Zinc has long been considered as one of the key players in host-pathogen interactions. The host sequesters intracellular zinc by utilizing multiple cellular zinc importers and exporters as a means of nutritional immunity. To overcome extreme zinc limitation within the host environment, pathogenic microbes have successfully evolved a number of mechanisms to secure sufficient concentrations of zinc for their survival and pathogenesis. In this review, we briefly discuss the zinc uptake systems and their regulation in the model fungus Saccharomyces cerevisiae and in major human pathogenic fungi such as Aspergillus fumigatus, Candida albicans, and Cryptococcus gattii.

• Journal of Nutrition and Health
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• v.28 no.5
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• pp.387-396
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• 1995

This study was undertaken to investigate the effect of increase in the ratio of zinc to copper and alcohol consumption on serum lipid content in Sprague-Dawley male rats during five weeks. Sixty rats were divided into six groups, CZ < zinc 30ppm diet >, CZA < zinc 30 ppm diet plus alcohol 5% solution >, HZ < zinc 300ppm diet >, HZA < zinc 300ppm diet plus alcohol 5% solution >, SHZ < zinc 600ppm diet >, SHZA < zinc 600 ppm diet plus alcohol 5% solution >. High ratio of zinc to copper groups < HZ, SHZ > were significantly decreased in high-density lipoprotein (p<0.01) and increased in total cholesterol, triglyceride, total lipid in serum(p<0.001, p<0.001, p<0.01). Triglyceride levels of serum in alcohol groups < CZA, HZA, SHZA > were significantly higher (p<0.001) than non-alcohol group < CCZ, HZ, SHZ >. Copper levels of serum were reduced in group high ratio of zinc to copper. These results present that high ratio of zinc to copper increase cholesterol(p<0.001) and alcohol consumption increase triglyceride(p<0.001) in serum. This close association to lipid metabolism in rats draw attention to the potential significance of zinc and alcohol nutriture in relation to cardiovascular disease.

• Korean Journal of Community Nutrition
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• v.14 no.2
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• pp.229-235
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• 2009

This study was carried out to determine whether a short-term zinc supplementation could improve the zinc status without adverse changes in copper status among type 2 diabetic patients. Seventy-six diabetic subjects and 72 normal adults participated in this study. Subjects were randomly divided into supplemented and control groups. Forty-four diabetic patients and 34 normal subjects were supplemented with 50 mg zinc gluconate daily for 4 weeks. Dietary intakes of participants were measured for two non-consecutive days by 24-hour recall method. Nutritional status of zinc and copper were also evaluated by biochemical measurement of fasting plasma samples and spot urinary collection. At baseline, diabetic patients showed significantly lower levels of dietary zinc intake and higher urinary zinc excretion than the normal adult group(p<0.05, p<0.0001). Plasma level of zinc was not significantly different between diabetic and normal adults at baseline. However, plasma zinc level increased significantly in both diabetic patients and normal adults after zinc supplementation. The changes in plasma copper levels following zinc supplementation were not statistically significant in diabetic subjects as well as in normal adults. These results indicated that four weeks of zinc supplementation did not influence Cu status and that it may contribute to improving the zinc status. Therefore, we suggest that Zn supplementation for a short-term period may improve marginal zinc status of diabetic patients without interfering with their copper status

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.3
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• pp.465-479
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• 2020

Objective: This study performed a meta-analysis of published trials to determine the effects of zinc on the immune response and production performance of broilers. Methods: A database was built from published literature regarding the addition of zinc forms or doses and their relation to the immune response and production performance of broilers. Different doses or forms of zinc were identified in the database. The recorded parameters were related to the immune response and production performance. The database contained a total of 323 data points from 41 studies that met the criteria. Then, the data were processed for a meta-analysis using a mixed model methodology. The doses or different forms of zinc were considered fixed effects, different studies were treated as random effects, and p-values were used as the model statistics. Results: An increase in zinc dose increased (p<0.05) pancreas metallothionein (MT) and zinc concentrations in the plasma, tibia and meat, all in quadratic patterns, but linearly decreased (p<0.05) the heterophil/lymphocyte (H/L) ratio. Regarding the different zinc forms, both inorganic and organic zinc increased (p<0.05) the zinc concentrations in the plasma and tibia, the calcium and phosphorus contents in the tibia, and the antioxidant activity of superoxide dismutase in meat as compared to control. An increase in zinc dose increased average daily gain (ADG) and decreased feed conversion ratio (FCR) following a quadratic pattern (p<0.05). Inorganic and organic zinc decreased (p<0.05) FCR and H/L ratio than that of control, but these two forms were similar for these parameters. Conclusion: Zinc addition has a positive impact on immunity and broiler production. Zinc can suppress stress and inhibit the occurrence of lipid peroxidation in broilers, and it can also improve ADG, FCR, and the quality of broiler carcasses.

• Journal of Nutrition and Health
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• v.53 no.4
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• pp.347-355
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• 2020

Purpose: Zinc is known to be associated with osteoblast proliferation and differentiation. Osterix as zinc-finger transcription factor is also related to osteoblast differentiation and bone formation. In the present study, we aimed to investigate whether zinc modulates osterix gene and protein expression in osteoblastic MC3T3-E1 cells. Methods: MC3T3-E1 cells were cultured in zinc-dependent concentrations (0, 0.5, 1, 5, or 15 µM Zn), along with osteogenic control (normal osteogenic medium) for 1 and 3 days. The gene and protein expression levels of osterix were analyzed by real-time reverse transcription polymerase chain reaction and Western blotting, respectively. Results: Zinc increased osteoblast proliferation in a concentration-dependent manner at day 1 and 3. Similarly, zinc increased the activity of osteoblast marker enzyme alkaline phosphatase in cells and media in a zinc concentration-dependent manner. Moreover, our results showed that the pattern of osterix gene expression by zinc was down-regulated within the low levels of zinc treatments (0.5-1 µM) at day 1, but it was up-regulated after extended culture period at day 3. Osterix protein expression by zinc showed the similar pattern of gene expression, which down-regulated by low zinc levels at day 1 and up-regulated back at day 3 as the early stage of osteoblast differentiation. Conclusion: Our results suggest that zinc modulates osterix gene and protein expression in osteoblasts, particularly in low level of zinc at early stage of osteoblast differentiation period.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.365-369
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• 2001

EAF's dust has been treated mainly by pyrometallurgical reduction process in rotary kiln furnace to recover valuable metal elements such as Zn and to avoid the disposal of hazardous materials to waste. Recently, hydrometallurgical eletrowinning of zinc from a zinc-amino chloride solution obtained by the leaching of EAF's dust was developed to recover high grade zinc metal from EAF’s dust. But there are some disadvantages in each process such as difficulty of operation condition control and sticking problem in kiln process and low extractability and recovery of zinc owing to insoluble zinc-ferrite in electrowinning process. We propose a new combined process of pyrometallurgical one and hydrometallurgical one to treat EAF's dust efficiently and economically. In this study, ammonium chloride solution leaching of crude zinc oxide recovered from reduction of EAF's dust was carried out to find out the efficiency of zinc extraction from it and the possibility for performance of eletrowinning in the proposed process. Effects of various leaching variables ruck as leaching temperature, concentration of leaching solution and leaching time were investigated. And the leaching results of the crude zinc oxide were compared with those of EAF's dust. The extraction percents of zinc in ammonium chloride solution leaching of the crude zinc oxide recovered from reduction of EAF's dust were above 80% after 60 minutes of leaching under the leaching condition of 4M NH$_4$CI concentration and above leaching temperature of 7$0^{\circ}C$. And the concentrations of zinc in the leached solution were obtained above 50g/$\ell$. The activation energy calculated for zinc extraction in NH$_4$CI leaching was 58.1 KJ/㏖ for EAF's dust and 15.8 KJ/㏖ for the crude zinc oxide recovered from reduction of EAF's dust.

• Nutrition Research and Practice
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• v.6 no.3
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• pp.221-225
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• 2012

Zinc deficiency is known to be associated with insulin resistance in obese individuals. This study was performed to evaluate the effect of zinc supplementation on insulin resistance and metabolic risk factors in obese Korean women. Forty obese women (body mass index (BMI) ${\geq}25kg/m^2$) aged 19-28 years were recruited for this study. Twenty women of the study group took 30 mg/day of supplemental zinc as zinc gluconate for 8 weeks and 20 women of control group took placebo. Usual dietary zinc intake was estimated from 3-day diet records. Insulin resistances were measured using Homeostasis model assessment (HOMA) indices, and insulin sensitivities Matsuda indices, which were calculated using oral glucose tolerance test data. Metabolic risk factors, such as waist circumference, blood pressure, fasting glucose, triglyceride, high density lipoprotein (HDL) cholesterol, and adipocyte hormones such as leptin, and adiponectin were also measured. At the beginning of study, dietary zinc averaged 7.31 mg/day and serum zinc averaged $12.98{\mu}mol/L$ in the study group. Zinc supplementation increased serum zinc by 15% and urinary zinc by 56% (P < 0.05). HOMA values tended to decrease and insulin sensitivity increased slightly in the study group, but not significantly so. BMI, waist circumference, blood pressure, blood glucose, triglyceride, HDL cholesterol, and adipocyte hormones did not change in either the study or control group. These results suggest that zinc status may not affect insulin resistance and metabolic risk factors in obese Korean women. Further research is required on a larger cohort with a longer follow-up to determine the effects of zinc status on insulin resistance and metabolic variables.