• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.3 no.2
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• pp.3-16
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• 1996

This study was investigated to the effect of oxygen barrier of four different packaging films of the shelf life of proessed meat product by the simulated distribution test and storage test. The microbial growth, pH, VBN content, TBA value, color change and sensory evaluation were compared during the 2-month storage period at 4, 10, $20^{\circ}C$ after finished the simulated distribution test. The oxygen transmission rates ($cc/m^2$ day) were BF001: 27,88; BF003; 12.30;NY; 77.98; EVOM; 0.41 respectively. The packaging films were not effected on the changes of pH, VBN content, TBA value and color during the storage period. The aerobic microbial growth was increased only at $20^{\circ}C$ in the order of growth rate in the following films;NY > BF001 > BF003 > EVOH. Therefore, the microbial growth was affected significantly by the properties of oxygen barrier off packaging films and it should be an indicator of establishing the shelf life processed meat product.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.286-287
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• 2012

Reset-first resistive switching mechanism based on reduction reaction in HfO2-x with oxygen drift-diffusion was studied. we first report that the indirect evidence of local filamentary conductive path formation in bulk HfO2 film with local TiOx region at Ti top electrode formed during forming process and presence of anion-migration at interface between electrode and HfO2 during resistive switching through high resolution transmission electron microscopy (HRTEM), electron disperse x-ray (EDX), and electron energy loss spectroscopy (EELS) mapping. Based on forming process mechanism, we expected that redox reaction from Ti/HfO2 to TiOx/HfO2-x was responsible for an increase of initial current with increasing the post-annealing process. First-reset resistive switching in above $350^{\circ}C$ annealed Ti/HfO2 film was exhibited and the redox phenomenon from Ti/HfO2 to TiOx/HfO2-x was observed with high angle annular dark field (HAADF) - scanning transmission electron microscopy (STEM), EDX and x-ray photoelectron spectroscopy. Therefore, we demonstrated that the migration of oxygen ions at interface region under external electrical bias contributed to bipolar resistive switching behavior.

• International Journal of Oral Biology
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• v.39 no.4
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• pp.229-236
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• 2014

Reactive oxygen species (ROS) and nitrogen species (RNS) are implicated in cellular signaling processes and as a cause of oxidative stress. Recent studies indicate that ROS and RNS are important signaling molecules involved in nociceptive transmission. Xanthine oxidase (XO) system is a well-known system for superoxide anions ($O{_2}^{{\cdot}_-}$) generation, and sodium nitroprusside (SNP) is a representative nitric oxide (NO) donor. Patch clamp recording in spinal slices was used to investigate the role of $O{_2}^{{\cdot}_-}$ and NO on substantia gelatinosa (SG) neuronal excitability. Application of xanthine and xanthine oxidase (X/XO) compound induced membrane depolarization. Low concentration SNP ($10{\mu}M$) induced depolarization of the membrane, whereas high concentration SNP (1 mM) evoked membrane hyperpolarization. These responses were significantly decreased by pretreatment with phenyl N-tert-butylnitrone (PBN; nonspecific ROS and RNS scavenger). Addition of thapsigargin to an external calcium free solution for blocking synaptic transmission, led to significantly decreased X/XO-induced responses. Additionally, X/XO and SNP-induced responses were unchanged in the presence of intracellular applied PBN, indicative of the involvement of presynaptic action. Inclusion of GDP-${\beta}$-S or suramin (G protein inhibitors) in the patch pipette decreased SNP-induced responses, whereas it failed to decrease X/XO-induced responses. Pretreatment with n-ethylmaleimide (NEM; thiol-alkylating agent) decreased the effects of SNP, suggesting that these responses were mediated by direct oxidation of channel protein, whereas X/XO-induced responses were unchanged. These data suggested that ROS and RNS play distinct roles in the regulation of the membrane excitability of SG neurons related to the pain transmission.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.70-73
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• 2002

Thin films of vanadium oxide($VO_{x}$) have been deposited by r.f. magnetron sputtering from $V_{2}O_{5}$ target in gas mixture of argon and oxygen. The oxygen/(oxygen+argon) partial pressure ratio of 0% and 8% is adopted. Crystal structure, chemical composition, molecular structure and optical properties of films sputter-deposited under different oxygen gas pressures and in-situ annealed in vacuum at $400^{\circ}C$ for 1h and 4h are characterized through XRD. RBS, FTlR and optical absorption measurements. The films as-deposited are amorphous and those annealed for time longer than 4h are polycrystalline. $V_{2}O_{5}$ and lower oxides co-exist in sputter-deposited films and as the oxygen partial pressure is increased the films become more stoichiometric $V_{2}O_{5}$. When annealed at $400^{\circ}C$, the as-deposited films are reduced to a lower oxide. It is observed that the oxygen atoms located on the V-O plane of $V_{2}O_{5}$ layer participate more readily in the oxidation and reduction process. The optical transmission of the films annealed in vacuum decreases considerably than the as-deposited films and the optical absorption of all the films increases rapidly between 400 and 550nm.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.210-210
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• 2012

Gas barrier coating from dense thin film deposition has been one of the important applications such as food-packaging and organic display. Especially for food-packaging, plastic container has been widely used due to its low price and high through-put in mass production. However, the plastic container with low surface energy like polypropylene (PP) has been limited to apply gas barrier coating. That is because a gas barrier coating could not adhere to PP due to its too low surface energy and high porosity of PP. In this research, we applied carbon coating consisting of Si and O as an interlayer between silicon oxide (SiOx) and PP. A carbon layer was found to provide better adhesion, which was experimentally proved by oxygen transmission rate (OTR) and SEM images. However, we also found that there is a limitation in the maximum thickness of a carbon layer and SiOx film due to their high stress level. For this conflict, we obtain the optimal thickness of a carbon layer and SiOx film showing optimal gas barrier property.

• Journal of the Korean Electrochemical Society
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• v.15 no.2
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• pp.90-94
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• 2012

We report nanostructure electrodes with $TiO_2$ as a core and carbon as a shell ($TiO_2$@C) for oxygen reduction in alkaline solution. The structure of core-shell electrodes is characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction method, and X-ray photoelectron microscopy. The electrochemical properties of the $TiO_2$@C electrodes are characterized using a potentiostat and compared with those of carbon supported Pt catalyst. In particular, the core-shell electrode with dominant pyridinic-N component exhibits an imporved electrocatalytic activity for oxygen reduction reaction in alkaline solution.

• Journal of Mechanical Science and Technology
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• v.19 no.11
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• pp.2068-2076
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• 2005

The influence of oxygen concentration and CO$_{2}$ as diluent in oxidizer side on soot characteristics was studied by Laser Induced Incandescence, Time Resolved LII and Transmission Electron Microscopy photography in non-premixed co flowing flames. Through the comparison of TEM photographs and the decay rate of LII signal, suitable two delay times of TIRE-LII method and signal sensitivity ($\Delta$S$_{TIRE-LII/) were determined. The effects of O$_{2}$ and CO$_{2}$ as diluent in oxidizer side on soot formation are investigated with these calibrated techniques. The O$_{2}$+CO$_{2}$, N$_{2}$, and [Ar+CO$_{2}$] mixture in co-flow were used to isolate CO2 effects systematically. The number concentration of primary particle and soot volume fraction abruptly decrease by the addition of CO$_{2}$ to the co-flow. This suppression is resulted from the short residence time in inception region because of the late nucleation and the decrease of surface growth distance by the low flame temperature due to the higher thermal capacity and the chemical change of CO$_{2}$ including thermal dissociation. As the oxygen concentration increases, the number concentration of soot particles at the inception region increases and thus this increase of nucleation enhances the growth of soot particle.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.192.1-192
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• 2003

The aim of this study was to develop a model that could be used in the design of modified atmosphere packaging (MAP) for Mandarin oranges. Respiratory data at 5, 10, 20$^{\circ}C$ for mandarin oranges were gathered and altered for create useful respiration model. The maximum rate of oxygen uptake increased with increasing temperature. The packaging materials were conventional low density polyethylene and polypropylene with anti-fog, and anti-fungi treatments, and thickness was 30 $\mu\textrm{m}$ and 50 $\mu\textrm{m}$. Permeability tests were performed to find their oxygen, carbon dioxide, water vapor transmission rate as increases in temperature. Test results were then converted to logarithm format for MAP modeling. Optimum gas composition in the package system for fruits were set according to literature and upper or lower limits of oxygen and dioxide established. To predict gas composition at certain storage time, weight of fruits, film thickness, film type, and other variables, respiration rate was studied at various storage conditions. The validity of the model was tested experimentally by observing actual atmospheric changes inside packages. It is concluded that the strategy developed is of use in designing dynamic gas exchange MAP systems, and also has potential uses in similar agricultural products.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.172-172
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• 2008

By thermal evaporation method, well-aligned ZnO nanowires were synthesized on sapphire substrate at $1000^{\circ}C$ with different oxygen flow rate by using pure ZnO powder (99.999 %). The as-synthesized ZnO nanowires were characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The well-aligned nanowires are single crystalline in nature and perpendicularly grown along the c-axis. Also the growth rate of nanowires, such as diameter and length, had a tendency to increase as oxygen flow rate increased. Based on the PL measurement of ZnO nanowires, we found that the near band edge of emission redshifted with the increasing intensity of the defect-related green emission in proportion to the increase of oxygen flow rate. "This research was supported by the Korea Research Foundation Grant funded by the Korean Government(MOEHRD)" (The Regional Research Universities Program/Chungbuk BIT Research-Oriented University Consortium).

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.3
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• pp.127-132
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• 2010

Reactive oxygen species (ROS), which include hydrogen peroxide ($H_2O_2$), the superoxide anion (${O_2}^-{\cdot}$), and the hydroxyl radical ($OH{\cdot}$), are generated as by-products of oxidative metabolism in cells. The cerebral cortex has been found to be particularly vulnerable to production of ROS associated with conditions such as ischemia-reperfusion, Parkinson's disease, and aging. To investigate the effect of ROS on inhibitory GABAergic synaptic transmission, we examined the electrophysiological mechanisms of the modulatory effect of $H_2O_2$ on GABAergic miniature inhibitory postsynaptic current (mIPSCs) in mechanically isolated rat cerebral cortical neurons retaining intact synaptic boutons. The membrane potential was voltage-clamped at -60 mV and mIPSCs were recorded and analyzed. Superfusion of 1-mM $H_2O_2$ gradually potentiated mIPSCs. This potentiating effect of $H_2O_2$ was blocked by the pretreatment with either 10,000-unit/mL catalase or $300-{\mu}M$ N-acetyl-cysteine. The potentiating effect of $H_2O_2$ was occluded by an adenylate cyclase activator, forskolin, and was blocked by a protein kinase A inhibitor, N -(2-[p-bromocinnamylamino] ethyl)-5-isoquinolinesulfonamide hydrochloride. This study indicates that oxidative stress may potentiate presynaptic GABA release through the mechanism of cAMP-dependent protein kinase A (PKA)-dependent pathways, which may result in the inhibition of the cerebral cortex neuronal activity.