• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.20 no.2
• /
• pp.41-49
• /
• 2014

This study illustrates the synthesis of gelatin based zinc oxide nanoparticle (ZnONPs) incorporated nanocomposite films using different concentrations of ZnONPs. The ZnONPs were oval in shape and the size ranged from 100- 200 nm. The nanocomposite films were characterized by UV-visible, FE-SEM, FT-IR, and XRD. The concentrations of ZnONPs greatly influenced the properties of nanocomposite films. The absorption peaks around 360 nm increased with the increasing concentrations of ZnONPs. The surface color of film did not change while transmittance at 280 nm was greatly reduced with increase in the concentration of ZnONPs. FTIR spectra showed the interaction of ZnONPs with gelatin. XRD data demonstrated the crystalline nature of ZnONPs. The thermostability, char content, water contact angle, water vapor permeability, moisture content, and elongation at break of nanocomposite films increased, whereas, tensile strength and modulus decreased with increase in the concentrations of ZnONPs. The gelatin/ZnONPs nanocomposite films showed profound antibacterial activity against both Gram-positive and Gram-negative food-borne pathogenic bacteria. The gelatin/$ZnONP^{1.5}$ nanocomposite film showed the best UV barrier and antimicrobial properties among the tested-films, which indicated a high potential for use as an active food packaging films with environmentally-friendly nature.

• Journal of Environmental Health Sciences
• /
• v.18 no.2
• /
• pp.135-145
• /
• 1992

This study was carried out to find out some characteristic responses of biological samples under the exposure of trace metals with the considering of Sex, age, residence period and smoking. Blood, Urine and Hair were collected from 116 dwellers in the vicinity of a smelting factory. Cd, Cu, Pb and Zn concentrations were determined by flame atomic absorption spectrophotometry and the following results were found important. 1) The concentrations of trace metals in the blood were 0.010+ 0.003 $\mu$g/ml in Cd, 0.82+ 0.11 $\mu$g/ml in Cu, 0.23_+ 0.13 $\mu$g/ml in Pb and 5.78_+ 1.43 $\mu$g/ml in Zn, those in the urine were 1.7_+ 1.7 $\mu$g/l in Cd, 16.5_+ 16.0 $\mu$g/l in Cu, 24.6_+ 23.0 $\mu$g/l in Pb and 367.7_+ 283.4 $\mu$g/l in Zn, and those in the hair were 0.52_+ 0.56 $\mu$g/g in Cd, 11.00_+4.01 $\mu$g/g in Cu, 8.53_+ 7.05 $\mu$g/g in Pb and 383.23_+ 110.56 $\mu$g/g in Zn. 2) In sex, the concentrations of Zn in the blood and urine of male were higher than those of female, however, the concentrations of Cd and Zn in the hair of female were higher than those of male. 3) The concentrations of Cd, Pb and Zn in the urine showed an increasing trend by age. 4) While the concentration of Cd in the urine increased, the concentration of Pb in the hair decreased by residential period in all the samples. 5) The concentrations of Cd and Zn in the blood and that of Zn in the urine of smoking group were higher than those of non-smoking group. The concentration of Pb in the blood of smoking group and those of Cd, Pb and Zn in the urine of non-smoking group showed increasing the trend by age. The concentrations of Cd and Zn in the urine of non-smoking group, the concentration of Zn in the hair of smoking group showed increasing trend by residential period, however, the concentrations of Pb in the blood and hair and that of Zn in the hair showed decreasing trend by residential period. 6) When the correlations of the concentrations between Zn (main smelting metal) and other metals were analyzed, Zn in the blood was significantly correlated with Cu, Pb and Zn in the urine (positively) and Zn in the urine was significantly correlated with Zn in the blood, Cd, Cu and Pb in the urine, and Pb in the hair (positively). Zn in the hair was significantly correlated with Cd in the urine and Cu in the hair (positively). 7) Consequently, it was useful to note that samples of urine showed higher sensitivity under the metal exposure than those of blood and hair in individual sampling. In addition, as trace metals showed higher accumulation in the hair of the groups, sampling of hair was more highly recommended than those of urine and blood in group sampling.

• Journal of the Korean Ceramic Society
• /
• v.35 no.2
• /
• pp.107-114
• /
• 1998

ZnO powder as phosphor was prepared by precipitation method with zinc acetate and ammonia solution and the size and shapes of precipitates were examined with variation of pH and concentration of solution. Its cathodoluminesence properties was evaluated with various heat tratment condition. Optimum con-dition for uniform precipitates was 11.8 of pH and 0.4M of concentration. ZnO:Zn phosphor was obtained by heat treatment of precipitates in reduction atmosphere using ZnS powder. With addition of 20wt% ZnS and 1 hour firing at 1000$^{\circ}C$ the highest cathodoluminescence was obtained.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.25 no.6
• /
• pp.481-485
• /
• 2012

ZnO nanowires were synthesized by hydrothermal technique. Prepared synthesis aqueous solutions were preserved by preheating in autoclave type synthesis equipment with various preheating time of 1 h difference. ITO-coated corning glass substrates deposited with AZO seed layers were then inserted in the preheated synthesis aqueous solutions and ZnO nanowires were grown for 180 min at $90^{\circ}C$. Density, length and aspect ratio of the grown ZnO nanowires were investigated. Composition, structural and optical properties of the grown ZnO nanowires were analyzed. Characteristics of the ZnO nanowires were comparatively studied in relation with $Zn^{2+}$ ion concentration measured directly after the preheating of synthesis aqueous solution.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.209.2-209.2
• /
• 2013

We proposed and fabricated zinc oxide thin-film transistors (TFTs) employing 4-mercaptophenol (4MP) doped ZnO by atomic layer deposition (ALD) that results in highly stable and high performance. The 4MP concentration in ZnO films were varied from 1.7% to 5.6% by controlling Zn:4MP pulses. The n-type carrier concentrations in ZnO thin films were controlled from $1.017{\times}10^{20}/cm^3$ to $2.903{\times}10^{17}/cm^3$ with appropriate amount of 4MP doping. The 4.8% 4MP doped ZnO TFT revealed good device mobility performance of 8.4 $cm^2/Vs$ and the on/off current ratio of 106. Such 4MP doped ZnO TFTs exhibited relatively good stability (${\Delta}V_{th}$: 2.4 V) under positive bias-temperature stress while the TFTs with only ZnO showed a 4.3 ${\Delta}V_{th}$ shift, respectively.

• Korean Journal of Materials Research
• /
• v.15 no.7
• /
• pp.431-434
• /
• 2005

To investigate the dependences of the absorption spectrum and electronic structure properties on the ZnO nano-particle size, ZnO nanocrystals were synthesized by a sol-gel method. The absorption onset peak exhibits a systematic blue-shift with decreasing particle size due to the quantum confinement effect, as well as, with decreasing $Zn^{2+}$ concentration. The increase of particle size is mainly controlled by coarsening and aggregation step during the nucleation and growth of ZnO nano-particles. The onset absorption spectrum of ZnO colloids changes from 310 to 355 nm as $Zn^{2+}$ concentration increases from 0.01 to 0.1 mole. The average particle size as a function of aging- time can be determined from the absorption spectra. The freshly prepared nanocrystal size was about 2.8nm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1995.11a
• /
• pp.22-24
• /
• 1995

The electrical conductivity of TiO$_2$doped ZnO was investigated by means of complex impedance measurement and voltage-current source and meaurement unit. The e1ectrical conductivity of TiO$_2$added ZnO was increased with increasing the concentration of TiO$_2$. The calculated relative dielectric constant was decreased with increasing the concentration of TiO$_2$. The increase of electrical conductivity seems to be the effect of TiO$_2$donor doping.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.421-422
• /
• 2013

Recently, ZnO has received attentionbecause of its applications in optoelectronics and spintronics. In order to investigate deep level defects in ZnO, we used N-doped ZnO with various of the N-doping concentration. which are reference samples (undoped ZnO), 27%, 49%, and 88%-doped ZnO. Photoinduced current transient spectroscopy (PICTS) measurement was carried out to find deep level traps in high resistive ZnO:N. In reference ZnO sample, a deep trap was found to located at 0.31 (as denoted as the CO trap) eV below conduction band edge. And the CN1 and CN2 traps were located at 0.09, at 0.17 eV below conduction band edge, respectively. In the case of both annealed samples at 200 and $300^{\circ}C$, the defect density of the CO trap increases and then decreases with an increase of N-doping concentration. On the other hands, the density of CN traps has little change according to an increase of N-doping concentration in the annealed sample at $300^{\circ}C$. According to the result of PICTS measurement for different N-doping concentration, we suggest that the CO trap could be controled by N-doping and the CN traps be stabilized by thermal annealing at $300^{\circ}C$.

• BMB Reports
• /
• v.31 no.1
• /
• pp.25-30
• /
• 1998

Kinetic studies of L-Alanine dehydrogenase from Bacillus subtilis-catalyzed reactions in the presence of $Zn^{2+}$ were carried out. The substrate (L-alanine) saturation curve is hyperbolic in the absence of the metal ion but it becomes sigmoidal when $Zn^{2+}$ is added to the reaction mixture indicating the positive cooperative binding of the substrate in the presence of zinc ion. The cooperativity of substrate binding depends on the xinc ion concentration: the Hill coefficients ($n_H$) varied from 1.0 to 1.95 when the zinc ion concentration varied from 0 to $60\;{\mu}m$. The inhibition of AlaDH by $Zn^{2+}$ is reversible and noncompetitive with respect to $NAD^+$ ($K_i\;=\;5.28{\times}10^{-5}\;M$). $Zn^{2+}$ itself binds to AlaDH with positive cooperativity and the cooperativity is independent of substrate concentration. The Hill coefficients of substrate biding in the presence of $Zn^{2+}$ are not affected by the enzyme concentration indicating that $Zn^{2+}$ binding does not change the polymerization-depolymerization equilibria of the enzyme. Among other metal ions, $Zn^{2+}$ appears to be a specific reversible inhibitor inducing conformational change through the intersubunit interaction. These results indicate that $Zn^{2+}$ is an allosteric competitive inhibitor and substrate being a non-cooperative per se, excludes the $Zn^{2+}$ from its binding site and thus exhibits positive cooperativity. The allosteric mechanism of AlaDh from Bacillus subtilis is consistent with both MWC and Koshland's allosteric model.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.101-101
• /
• 2010

ZnO shows a direct band gap of 3.37eV, large exciton binding energy (~60 meV), high oxidation ability, high sensitivity to many gases, and low cost, and it has been used in various applications such as transparent electrodes, light emitting diodes (LEDs), gas sensors and photocatalysts. Among these applications ZnO as photocatalyst has considerably attracted attention over the past few years because of its high activities in removing organic contaminants generated from industrial activities. In this research, ZnO nanoparticles were synthesized by spray-pyrolysis method using the zinc acetate dihydrate as starting material at synthesis temperature of $900^{\circ}C$ with concentration varied from 0.01 to 1.0M. The physical and chemical properties of the synthesized ZnO nanoparticles were examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transformation Infrared (FT-IR), and UV-vis spectroscopy. The Miller indices of XRD patterns indicate that the synthesized ZnO nanoparticles showed a hexagonal wurtzite structure. With increased precursor concentration, a primary, secondary particle sizes of ZnO nanoparticles increased by 0.8 to $1.5{\mu}m$ and 15 to 35nm, and their crystallinity was improved. Methyleneblue (MB) solution ($1{\mu}M$) as a test comtaminant was prepared for evaluating the photocatalytic activities of ZnO nanoparticles synthesized in different precursor concentration. The results show that the photocatalytic efficiency of ZnO nanoparticles was gradually enhanced by increased precursor concentration.