• Transactions on Electrical and Electronic Materials
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• 제18권3호
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• pp.155-158
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• 2017

In this paper, ZnO Thin Film Transistors (TFTs) were fabricated by a sol-gel method using a low-temperature process, and their physical and electrical characteristics were analyzed. To lower the process temperature to $200^{\circ}C$, we used a zinc nitrate hydrate ($Zn(NO_3)_2{\cdot}xH_2O$) precursor. Thermo Gravimetric Analyzer (TGA) analysis showed that the zinc nitrate hydrate precursor solution had 1.5% residual organics, much less than the 6.5% of zinc acetate dihydrate at $200^{\circ}C$. In the sol-gel method, organic materials in the precursor disrupt formation of a high-quality film, and high-temperature annealing is needed to remove the organic residuals, which implies that, by using zinc nitrate hydrate, ZnO devices can be fabricated at a much lower temperature. Using an X-Ray Diffractometer (XRD) and an X-ray Photoelectron Spectrometer (XPS), $200^{\circ}C$ annealed ZnO film with zinc nitrate hydrate (ZnO (N)) was found to have an amorphous phase and much more oxygen vacancy ($V_o$) than Zn-O bonds. Despite no crystallinity, the ZnO (N) had conductance comparable to that of ZnO with zinc acetate dihydrate (ZnO (A)) annealed at $500^{\circ}C$ as in TFTs. These results show that sol-gel could be made a potent process for low-cost and flexible device applications by optimizing the precursors.

• Asian-Australasian Journal of Animal Sciences
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• 제17권10호
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• pp.1378-1382
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• 2004

Zinc (Zn) is a micromineral and functions as a cofactor of many enzymes and its deficiency induces retardation of growth and dysfunction of the immune system in animals. This study was conducted to determine lipogenic activity of Zn in bovine intramuscular adipocytes. Preadipocytes were isolated from intramuscular fat depots of 26 month old Korean (Hanwoo) steers and cultured in media containing Zn. At confluence, the cells were treated with insulin, dexamethasone, and 1-methyl-3-isobutyl-xanthine to induce differentiation (accumulation of lipid droplets in cells). The sources of Zn were zinc chloride (${ZnCl}_2$) and zinc sulfate (${ZnSO}_4$), and the final concentrations of both Zn sources were 0, 5, 25, 50 and 100 ${\mu}$M. Glycerol-3-phosphate dehydrogenase (GPDH) activity, an index of adipocyte differentiation, was increased as the concentration of Zn in media increased showing the highest activity (25.74 ng/min/mg protein) at 25 ${\mu}$M of ${ZnSO}_4$. Supplementation of Zn during differentiation of bovine intramuscular adipocytes tended to decrease the production of nitric oxide (NO). Peroxisome proliferator-activated receptor gamma 2(PPAR$\gamma$2) gene expression was increased 10 days after differentiation induction. The current results indicate that Zn has a strong lipogenic activity in cultured bovine intramuscular adipocytes with remarkable suppression of NO production.

• 한국결정성장학회지
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• 제21권5호
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• pp.205-209
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• 2011

ZnO는 반도전성과 초전도성을 나타내며 광학적으로도 독특한 재료로 가스센서, 태양전지, 광학도파관 등 여러 방면에 널리 활용되고 있다. 본 논문에서는 이러한 ZnO에 Al을 첨가함에 따라 광학적 특성에 어떠한 영향을 미치는지 알아보기 위하여 ZnO에 Al 첨가량 변화에 따른 나노구조체를 제작하여 특성을 비교하였다. ZnO 용액은 PVP, ethanol, zinc acetate를 이용하여 Sol의 형태로 제작하였으며, Al첨가용액을 넣어 Al이 첨가된 ZnO Sol을 제작하였다. 제작된 Sol을 전기 방사법을 이용하여 나노구조체를 제조하였다. 제조된 섬유들을 각각 300, 500, $700^{\circ}C$로 열처리 한 후 나노 구조체를 XRD, XPS, SEM을 이용하여 분석하였다. 또한 TGA, DSC를 이용하여 온도변화에 따른 질량 및 열량의 변화를 측정하였다. UVvis를 이용하여 ZnO와 Al이 첨가된 ZnO의 흡광도를 측정 비교하였다.

• Journal of Nutrition and Health
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• 제30권4호
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• pp.406-414
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• 1997

It has been known that dietary phytate decreases the absorption of body zinc pool which is composed of the dietary and endogenous zinc in the body. The purpose of this study was to examine the effect of phytate on the absorption of total bodyzinc in Zn-depleted rats. Rats were Zn-depleted with either low(0.8%) or high(1.6%) Ca diet containing sodium phytate for 4 weeks. After zinc depletion, rats were assigned into phytate or non-phytate dietary groups within each low-or high-Ca dietary group. ant feces were collected for 2 weeks of the initial collection and 1 week after dietary crossover, during which the phytate and the non-phytate diet was switched over within the same Ca group. The content of Zn and Ca measured by atomic absorption spectrophotometer and phytate content was analyzed. food intake was higher in the high Ca group than in the low Ca group(p <0.0001), and was also higher in the non-phytate group than in the phytate group(p <0.0001). Food intake and phytate level affected body weight gain in rats(p <0.0001). Zinc excretion in the total feces was higher in the phytate group than in the non-phytate group at both low and high Ca level(p <0.0001), except during the crossover collection period in high Ca group. Calcium, however, didn't show any synergistic effect on phytate effect(p <0.05). This study showed that phytate decreased the absorption of total body zinc at both low and high Ca levels in Zn-depleted rats. A large portion of total body zinc originated from the endogenous zinc pool in these rats. The results of the present study showed the same effect of phytate on the endogenous zinc in Zn-depleted rats as in a previous study, confirming that phytate adversely affects zinc bioavailability, especially under marginal and poor zinc nutrition.

• E2M - 전기 전자와 첨단 소재
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• 제8권4호
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• pp.400-405
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• 1995

ZnO films have been grown easily with the conventional thermal evaporation method on SiO$\_$2/ coated Si wafers. Anhydrous zinc acetate has been used as evaporation source. Zinc-acetate was directly heated in the laboratory-made brass boat. Zinc-acetate was sublimed at the boat temperature of about 220.deg. C. The substrates were heated to 600.deg. C with home made tantalium heater. Oxygen has been flowed into the deposition chamber to change the partial pressure of oxygen. X-ray diffraction patterns showed all the films to be amorphous. The films deposited at high oxygen pressure exhibit higher resistivity than films at low pressure. Energy dispersive spectroscopy(EDS) and rutherford backscattering spectrometry(RBS) were conducted on the films to reveal the composition of the ZnO films.

• 한국분말재료학회지
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• 제20권5호
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• pp.371-375
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• 2013

ZnO nanoparticles in the size range from 5 to 15 nm were prepared by zinc-lithium-acetate system. The morphologies and structures of ZnO were characterized by TEM, XRD and FT-IR spectra. UV-visible results shows that the absorption of ZnO nanoparticles is blue shifted with decrease in particles size. Furthermore, photoluminescence spectra of the ZnO nanoparticles were also investigated. The ZnO nanoparticles have strong visible-emission intensity and their intensities depend upon size of ZnO nanoparticles.

• Korean Chemical Engineering Research
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• 제55권6호
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• pp.785-790
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• 2017

To collect zinc, Fe and Zn in spent pickling solution were extracted by using TBP (tributyl phosphate), and Zn was recovered from extracted solution to zinc oxalate particles by oxalic acid solution. The reusability of TBP solvent was also tested. The distribution coefficient of Zn was not affected by the concentration of Fe in spent pickling solution, almost constant with the values of 7.12~9.31 when extracted by TBP solvent. It was found that the extraction capacity of TBP solvent for Zn is higher than that for Fe. The extraction efficiency of Zn was higher than 95%, while most of Fe was left in aqueous phase. After the recovery, the used TBP solvent could be repeatedly reused for the extraction of Zn up to eight times. XRD analysis showed that zinc oxalate ($ZnC_2O_4$ $2H_2O$) was formed from the reaction of Zn-TBP and oxalic acid. From the results of SEM analysis, the formation of zinc oxalate particle was strongly affected by the concentration of oxalic acid. In summary, Zn in spent pickling solution was successfully separated and recovered with TBP solvent and oxalic acid solution, respectively.

• 자원리싸이클링
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• 제29권6호
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• pp.35-40
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• 2020

본 연구에서는 zinc bath 프로세스에 의한 폐초경합금의 재활용 시 중요한 반응온도, 시간 및 아연의 첨가량 등 반응 메카니즘을 조사하기 위해 기초실험을 수행하였다. 그 결과, zinc bath 반응은 용융 아연(Zn)과 폐초경합금 내측의 코발트(Co)의 반응을 촉진시키기 위해 800℃ 이상에서 가열하는 것이 요구되었다. 또한 폐초경합금의 두께는 800℃에서 0.5~2시간 동안의 zinc bath 프로세스에 있어서 반응시간의 증가에 따라 선형적으로 감소하였으며, 아연의 증발 감소량을 줄이기 위해서는 800℃이하에서 3시간 가열된 후에 2.0×10 torr-2이상의 진공분위기로 900℃이상에서 1시간 동안 가열하는 것이 적합한 것으로 조사되었다.

• Nutritional Sciences
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• 제5권4호
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• pp.190-196
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• 2002

Zinc deficiency has been shown to result in poor appetite, causing anorexia. However, the role of zinc in the regulation of food intake is not well understood. In the present study, we hypothesized that zinc deficiency dysregulates circulating leptin level and leptin mRNA gene expression, and that whether these changes were occuring as a direct result of, or as a compensatory effect of zinc deficiency in rats. After an adaptation period of 4 weeks, Sprague Dawley rats were provided with three different level of zinc, as one week of a Zn-adequate (30 mg/kg) diet, then two weeks of a Zn-depletion (1 mg/kg ), and finally by two weeks of a Zn-repletion (50 mg/kg) diet. At the end of each dietary experimental period, one third of the 26 rats were killed. Zinc levels of blood subfractions (plasma, yee blood cells and mononuclear cells) and in the liver were substantially decreased, despite the fact that food intake was not substantially decreased during the Zn-depletion period. Serum leptin concentration was significantly increased during the zinc depletion period. Leptin mRNA in adipose tissue was also shown to be highly expressed during the Zn-depletion period. Presumably, increased leptin level and leptin mRNA induction during Zn-depletion conditions may be the cause of lowered appetite which is the common symptom of Zn-deficiency. In conclusion, These increases in circulating leptin levels and in leptin gene expression would be the direct result of, rather than the compensatory effect of, zinc deficiency.

• Preventive Nutrition and Food Science
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• 제16권2호
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• pp.174-178
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• 2011

The cell permeability and cytotoxic effects of different-sized zinc oxide (ZnO) particles were investigated using a human colorectal adenocarcinoma cell line called Caco-2. Morphological observation by scanning electron microscopy revealed that three zinc oxides with different mean particle sizes (ZnO-1, 20 nm; ZnO-2, 90~200 nm; ZnO-3, $1\sim5\;{\mu}m$) tended to aggregate, particularly in the case of ZnO-1. When cytotoxicities of all three sizes of zinc oxide particles were measured at concentration ranges of $1\sim1000\;{\mu}g$/mL, significant decreases in cell viability were observed at concentrations of $50\;{\mu}g$/mL and higher. Among the three zinc oxides, ZnO-1 showed the lowest viability at $50\;{\mu}g$/mL in Caco-2 cells, followed by ZnO-2 and ZnO-3. The permeate concentration of ZnO-1 from the apical to the basolateral side in the Caco-2 model system after four hours was about three-fold higher than that of either ZnO-2 or ZnO-3. These results demonstrated that ZnO-1, with a 20 nm mean particle size, had poorer viability and better permeability in Caco-2 cells than ZnO-2 and ZnO-3.