• 펄프종이기술
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• 제43권5호
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• pp.1-10
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• 2011

In this study, 13 water soluble polymers(6 natural polymer, 7 synthetic polymer) were treated on Hanji. Mechanical properties, morphology and oxidation index with thermal aging were measured on the aged Hanji, dewaxed Hanji and polymer treated Hanji. 3 natural polymer(such as CMC, EC, MC) and 3 synthetic polymers(such as PVA 1500, 2000, PEG 1500) treated Hanji had higher strength than other polymer treated Hanji. The oxidation index of 3% methyl cellulose solution treated Hanji did a little increase with thermal aging. Finally, methyl cellulose was found to be the most efficient method for strengthening the dewaxed Hanji. The best aging safety and thermal stability were obtained at the methyl cellulose 3% water solution.

• 펄프종이기술
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• 제44권1호
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• pp.1-9
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• 2012

In this study, 5 solvent soluble polymers were treated on Hanji. Mechanical properties, morphology and oxidation index with thermal aging were measured on the aged Hanji, dewaxed Hanji and polymer treated Hanji. Synthetic polymers(such as polylactic acid, polybutylene succinate, polystyrene) treated Hanji had higher strength and thermal stability than cellulose derivatives(such as cellulose nitrate and cellulose acetate) treated Hanji. Polymer treated Hanji showed a little bit of color change. The oxidation index of PS treated Hanji did not increase with thermal aging because it did not have a carboxyl group in chemical structure. Finally, polystyrene was found to be the most efficient method for strengthening the dewaxed Hanji. The best aging safety and thermal stability were obtained at the polystyrene 3% solution.

• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.2861-2866
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• 2012

Results of the comparisons of various density functional theory (DFT) methods with different basis sets for predicting the molecular geometry of TPOP24N-Oxide macrocycle, an oxoporphyrin N-oxide, are reported in this paper. DFT methods, including M06-2X, B3LYP, LSDA, B3PW91, PBEPBE, and BPV86, are examined. Different basis sets, such as 6-$31G^*$, 6-31+G (d, p), 6-311+G (d, p), and 6-311++G (d, p), are also considered. The M06-2X/6-$31G^*$ level is superior to all other density functional methods used in predicting the geometry of TPOP24N-Oxide. The geometries of regioisomeric chlorin N-oxide and oxoporphyrin N-oxide are reported using M06-2X/6-$31G^*$ method. The geometry effects of oxoporphyrin and chlorin N-oxide regioisomers are increased ${\beta}-{\beta}$ bond lengths by N-oxidation because the bond overlap index due to charge transfers is decreased. In N-oxidation ring (II, III), angles that include ${\beta}-{\beta}$ bond length increase as the bond overlap index of ${\beta}-{\beta}$ bond is decreased by N-oxidation. The potential energy surfaces of chlorin N-oxide and oxoporphyrin N-oxide are explored by M06-2X/6-$31G^*$, and single-point calculations are performed at levels up to M06-2X/6-311++G (d, p). Total and relative energies are then calculated. The results indicate that chlorin 24 N-oxides are more stable than chlorin 22 N-oxides in chlorin N-oxide regioisomers. Moreover, TPOP24N-Oxide is less stable than TPOP22N-Oxide.

• Applied Microscopy
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• 제47권3호
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• pp.131-147
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• 2017

In this work further optical and electrical investigations of pure and Zr doped $Mn_3O_4$ (from 0 up to 20 at.%) thin films as a function of frequency. First, the refractive index, the extinction coefficient and the dielectric constants in terms of Zr content are reached from transmittance and reflectance data. The dispersion of the refractive index is discussed by means of Cauchy model and Wemple and DiDomenico single oscillator models. By exploiting these results, it was possible to estimate the plasma pulse ${\omega}_p$, the relaxation time ${\tau}$ and the dielectric constant ${\varepsilon}_{\infty}$. Second, we have performed original ac and dc conductivity studies inspired from Jonscher model and Arrhenius law. These studies helped establishing significant correlation between temperature, activation energy and Zr content. From the spectroscopy impedance analysis, we investigated the frequency relaxation phenomenon and hopping mechanisms of such thin films. Moreover, a special emphasis has been putted on the effect of the oxidation in air of hausmannite thin films to form $Mn_2O_3$ ones at $350^{\circ}C$. This intrigue phenomenon which occurred at such temperature is discussed along with this electrical study. Finally, all results have been discussed in terms of the thermal activation energies which were determined with two methods for both undoped and Zr doped $Mn_3O_4$ thin films in two temperature ranges.

• 한국물환경학회지
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• 제25권4호
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• pp.589-596
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• 2009

The spectroscopic characteristics and chemical oxygen demand (COD) oxidation efficiencies were investigated for dissolved organic matters (DOM) from diverse sources, which may indirectly affect the concentrations and the quality of DOM found in watersheds. The DOM investigated for this study showed a wide range of the percent distributions of refractory organic matter (R-OM) from 8 to 100%. Relatively high R-OM distributions were observed for the DOM with the source of head water, sediments, paddy soils, field soils, and treated sewage whereas the DOM from livestock waste, reed, weeds, algae, and attached algae exhibited lower R-OM percent distributions. The percent distribution of R-OM had positive correlations with specific UV absorbance (SUVA) and humidification indices (HIX) of DOM. The investigated DOM was classified into four different source groups (i.e., biota, vegetables, soils, sediments) by comparing the synchronous fluorescence spectra. The DOM group from biota source was characterized by a prominent presence of protein-like fluorescence (PLF) whereas fulvic-like fluorescence (FLF) was additionally observed for vegetable-source DOM. FLF became significant for the DOM from both soils and sediments although no PLF was found for soil-derived DOM. A range of COD oxidation efficiency was observed for the various DOM, ranging from 36 to 94% and from 65 to 125% for $COD_{Mn}$ and $COD_{Cr}$, respectively. The results indicate that $COD_{Cr}$ reflects the higher OM concentration than $COD_{Mn}$. However, 95% confidence intervals of the COD oxidation efficiencies were similar for the two types of COD, suggesting that $COD_{Cr}$ may not be the superior OM index to $COD_{Mn}$ in terms of the variability of the oxidation efficiency. No significant correlations were obtained between COD oxidation efficiencies and the spectroscopic characteristics of DOM for this study.

• 공업화학
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• 제25권4호
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• pp.418-424
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• 2014

본 연구에서는 NaCl/$H_3PO_4$ 혼합수용액을 사용하여 라이오셀 섬유의 내염화 처리를 수행하고 이에 따른 열 안정성과 내산화성의 향상 효과를 고찰하였다. 라이오셀 섬유를 다양한 공정조건으로 내염화 처리한 후 열 안정성과 내산화성을 측정 및 분석하고 그에 따른 메커니즘을 제시하였다. 실험결과, 내염화 처리된 라이오셀 섬유의 적분 열분해 온도(integral procedural decomposition temperature, IPDT)와 한계산소지수(limited oxygen index, LOI)는 약 23, 30% 증가하였으며, 활성화 에너지(activation energy, $E_a$) 값은 약 24% 향상된 것을 알 수 있었다. 이러한 결과는 $H_3PO_4$와 NaCl가 연소시 에스테르화 반응, 탈수소화 반응 및 C-C결합의 분해반응으로 char 형성을 촉진하고 섬유 표면에 형성된 탄소 층을 형성함으로써, 고분자 수지 내부로 산소와 열 공급을 물리적으로 차단하여 열 안정성과 내산화성이 향상된 것으로 판단된다. 이러한 결과를 바탕으로, NaCl/$H_3PO_4$ 혼합수용액을 이용한 내염화 처리 공정의 최적화된 인자 및 메커니즘을 제시하였고 열 안정성과 내산화성이 향상된 라이오셀을 성공적으로 제조하였다.

• 유기물자원화
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• 제15권1호
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• pp.178-184
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• 2007

분변토 처리의 기계화 및 자동화 공정 개발을 위하여, 본 연구에서는 슬러지 침출액을 이용한 지렁이 퇴비화 지표에 대하여 고찰하였다. 이 연구에서는 회분식 및 연속식 실험을 위하여 현장 하수 슬러지가 사용되었다. 슬러지 처리방버버에 따른, 발생되는 침출수의 이화학적 특성 변화는 거의 유사함을 나타내었다. 그러나, 산화환원전위, pH, 전기전도도, $NH_3-N$ 항목에서는 퇴비화 전후, 분명한 차이를 보였다. 또한, 지렁이 퇴비화 지표 설정에 가장 적합한 변수들은 ORP과EC임을 알 수 있었다. 이러한 연구 결과들은 실제적으로 분변토 처리가 이루어지는 지렁이 퇴비하 기술로 사용될 수 있을 것이다.

• Toxicological Research
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• 제20권3호
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• pp.213-223
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• 2004

This work aimed to study the effectiveness of cellular oxidative parameter (malondial-dehyde, protein carbonyl, and 8-hydroxy-2'deoxyguanosine). The experimental groups were aluminum treated rats and control rats. Aluminum treatd rats were given intraperitoneally aluminum nitrate nonahydrate ($Al^{3+}$, 0.2 mmol/kg) daily for 30 days except Sunday. Control rats were injected 1 ml of saline. After the dose, rats were decapitated and hippocampus and cerebral cortex were removed. The measured parameters were tissue malondialdehyde (MDA, index of lipid peroxidation), protein carbonyl (index of protein oxidation), 8-hydroxy-2'-deoxy-guanosine (8-OHdG, index of DNA oxidation), reduced glutathione (GSH) levels as well as glutathione reductase (GR) and catalase. AI concentrations in the tissues were also measured. All results were corrected by tissue protein levels. The results were as followed; 1. The concentrations of AI in the cortex and hippocampus were significantly higher in the AI-treated rats than in the control rats. 2. Antioxidative enzyme's activity, catalase and GR, were significantly higher in the AI-treated rats than the control rats. GSH levels were also higher in the AI-treated rats. 3. MDA, protein carbonyl, and 8-OHdG concentration of AI-treated rats were significantly higher than those of control rats. 4. The concentrations of antioxidants, and oxidative stress parameter were correlated with the concentrations of AI in hippocampus and cerebral cortex. Catalase and GR activity were also correlated with the concentration of AI. Based on these results, it can be suggested that intraperitoneally injected AI was accumulated in the brain and induced the increase of antioxidant levels and antioxidative enzyme activity. Also, the oxidative products of cellular macromolecules are significantly related to tissue AI concentration. Therefore MDA, protein carbonyl, and 8-OHdG are useful markers for oxidative stress on cellular macromolecules.

• 한국포장학회지
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• 제26권1호
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• pp.19-23
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• 2020

Al-laminated packaging film incorporating ascorbic acid or tocopherol at inner food contact layer was tested in the potential to improve antioxidative preservation of powdered infant formula under CO₂-enriched atmosphere. Product of 200 g was packaged with the packaging film containing 0.3% antioxidant in sealant layer of low density polyethylene and stored at 30℃ for 286 days with periodic measurement of package atmosphere and product's quality attributes. The CO₂-flushed package resulted in shrinkage of tight contact between the product and the film not allowing gas sampling of package atmosphere after 140 days. Package of tocopherol-incorporated film allowed some ingress of oxygen after 112 days presumably due to its weakening of heat-seal area. The increased oxygen concentration in the tocopherol-added film package led to the concomitant increase of peroxide value, an index of lipid oxidation. On the other hand, packaging of ascorbic acid-added film pouch could suppress lipid oxidation marginally in consistent manner compared to control package without any antioxidant.

• Fisheries and Aquatic Sciences
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• 제17권2호
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• pp.189-195
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• 2014

Headspace volatile compounds of cold-stored and freeze-dried Krill Eupausia superba were analyzed to investigate their flavor qualities using a system combining a dynamic headspace isolator, an automatic thermal desorber, and a gas chromatograph-mass-selective detector. Levels of oxidation products of polyunsaturated fatty acids such as aldehydes, alcohols, and ketones, which are known to give seafood a nasty smell because of their low flavor threshold values, increased during cold storage of krill. Notably, levels of 2-methylpropanal, 3-methylbutanal, 2-methylbutanal and 2-butanone increased during its storage. They can be considered index compounds of off-odor according to freshness degradation during storage. By contrast, in freeze-dried krill powder, levels of aldehydes, ketones, and aromatic compounds decreased rapidly. Only alcohols, which did not greatly affect the food flavor, were isolated in large amounts. It was confirmed that levels of oxidized compounds of krill increased during cold storage, but decreased in freeze-dried krill.