• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1753-1758
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• 2012

A novel, efficient and controlled protocol for the synthesis and enhanced photocatalytic activity of $Au@TiO_2$ nanocomposite is developed. $TiO_2$ (P25) was pretreated by employing UV light (${\lambda}$ = 254 nm) and the pretreated $TiO_2$ was uniformly decorated by gold nanoparticles (AuNPs) in presence of sodium citrate and UV light. UV pretreatment makes the $TiO_2$ activated, as electrons were accumulated within the $TiO_2$ in the conduction band. These accumulated electrons facilitate the formation of AuNPs which were of very small size (2-5 nm), similar morphology and uniformly deposited at $TiO_2$ surface. It leads to formation of stable and crystalline $Au@TiO_2$ nanocomposites. The rapidity (13 hours), monodispersity, smaller nanocomposites and easy separation make this protocol highly significant in the area of nanocomposites syntheses. As-synthesized nanocomposites were characterized by TEM, HRTEM, TEM-EDX, SAED, XRD, UV-visible spectrophotometer and zeta potential. Dye degradation experiments of methyl orange show that type I ($Au@TiO_2$ nanocomposites in which $TiO_2$ was pretreated with UV light) has enhanced photocatalytic activity in comparison to type II ($Au@TiO_2$ nanocomposites in which $TiO_2$ was not pretreated with UV light) and $TiO_2$ (P25). This shows that pretreatment of $TiO_2$ provides type I a better catalytic activity.

• Asian-Australasian Journal of Animal Sciences
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• 제11권5호
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• pp.491-497
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• 1998

Four types of serum supplements viz. estrus cow serum (ECS), estrus buffalo serum (EBS), pro-estrus buffalo serum (PrBS) and post-estrus buffalo serum (PtBS), added to TCM-199, were evaluated for in vitro maturation and fertilization of buffalo follicular oocytes. The oocytes were recovered from buffalo ovaries after slaughter, using either aspiration or scoring (multiple incisions) method. The recovered oocytes were categorized as A, B and C based on their cumulus investment and ooplasm homogeneity and cultured in four media. The in vitro matured oocytes were inseminated with $1{\times}10^6$ spermatozoa washed in 2.9% sodium citrate solution. The scoring method yielded greater number of morphologically good oocytes than the aspiration method (3.85 vs 1.76 per ovary, p < 0.01). The maturation rates of three categories of oocytes did not differ from one another. The maturation rates of 80.00, 82.08, 78.77 and 66.23%, while the fertilization rates of 54.54, 55.38, 52.80 and 36.76% were recorded for media containing ECS, EBS, PrBS, and PtBS, respectively. The medium containing PtBS gave lower maturation, as well as fertilization, rates than the other three media (p < 0.05). Thus, the scoring method was better than the aspiration method for the recovery of follicular oocytes. The oocytes categorized A, B and C had similar maturation capabilities. The TCM-199 containing buffalo/cow serum collected at pro-estrus or estrus appeared better for in vitro maturation and fertilization of buffalo follicular oocytes than that containing serum collected at post estrus.

• 한국식품조리과학회지
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• 제18권6호
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• pp.603-612
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• 2002

The study was carried out to compare the relation between the color intensity and antioxidant activity of caramelization products using xylose(XY), glucose(GL). sucrose(SU), glucose＋citric acid(GLCA), glucose＋sodium citrate(GLSC), heated at 80, 120 and 140$\^{C}$ for 24hrs, respectively. The color intensity(absorbance at 490nm) of the browning mixtures increased as the browning temperature and time increased. But the degrees of color intensity of SU and GLCA changed very little. The hydrogen donating ability(HDA) of browning reaction products was generally enhanced as the browning temperature and time increased. When browning mixtures were heated at 80$\^{C}$, the HDA of GLGC was the highest, but the HDA of GLSC was the highest when heated at 120 and 140$\^{C}$. The antioxidant activities for the corn oil substrate containing the anhydrous ethanol extracts from the browning mixtures was inferior to that of SU, but was superior to that of GLCA. The relations among the color intensity, the antioxidant activity, and the hydrogen donating ability(HDA, reducing power) of the browning reaction mixtures were as follows: As the color intensity increased, the antioxidant activity decreased. The correlation coefficient of the color intensity and the antioxidant activity by regression equation was -0.73 ∼ -0.82. As the reducing power increased, the antioxidant activity decreased. The correlation coefficient between the reducing power and the antioxidant activity by regression equation was -0.98 ∼ -0.99. Therefore, the antioxidant activity of browning reaction mixtures seemed not correlated with the color intensity and the reducing power.

• 대한수의학회지
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• 제32권3호
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• pp.421-427
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• 1992

The study was basically carried out to establish the appropriate condition for applying the Westergren method for erythrocyte sedimentation rate(W-ESR) in Throughbred racehorses at recess. To do this, we examined the correlationship among some factors including the kind of anticoagulants, optimal ambient temperature and reading time for W-ESR in healthy racehorses. The difference between the blood samples treated with only 3.8% solution of sodium citrate(SC) and both EDTA and SC as a coagulant, there was not recognized any significant difference(p<0.05) in the levels of W-ESR irrespective of the ambient temperature of $20^{\circ}C$ or $30^{\circ}C$. The best optimal ambient temperature for W-ESR in horses was proved at $30^{\circ}C$ resulting from the tendency of the most reduced dispersion in mean values analyaed from repeatly 4 times to the same blood samles compared with those of $10^{\circ}C$ and $20^{\circ}C$. The optimal reading time was determined as 60 minutes(Y=237.2~4.1X, $r^2=0.998$) and 70 minutes(Y=247.8~4.2X, $r^2=0.999$) under the same temperature of $30^{\circ}C$; the latter showed the better result on the basis of the correlation of packed cell volume(PCV) and ESR values. About 13 healthy racehorses, we compared the real values of W-ESR respectively obtained at 60 minutes and 70 minutes at $30^{\circ}C$ with the anticipated values of PCV by means of the analysis of linear regression equitation. As the result of this, the strong correlation between both of them was confirmed. For practical use of W-ESR in Thoroughbred racehorese, we can recommend the condition of 60 or 70 minutes for the optimal reading time as well as $30^{\circ}C$ for the best ambient temperature.

• 한국미생물·생명공학회지
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• 제29권3호
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• pp.186-193
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• 2001

경북 경주지역의 저병해 고추경착지역의 토양으로부터 생물학적 방제기작중의 하나인 항생물질을 생산하는 길항미생물을 분히하기 위하여 70여종의 세균을 분리하였으며 이들을 대상으로 고추역병균 Phytophthora capsici를 가장 강력하게 길항하는 균주를 최종 선발하였다. 선발균주는 Chryseomonas luteola로 동정되었고 방제 기작은 약한 siderophore 생산성과 cellulase 생산성도 기인되었으나 항생물질 생산성이 주요 기작임을 확인하였다. 항진균성 항생물질의 대량생산의 기초자료로 활용하고자 항생물질 생산의 최적배지 조건 및 배양조건을 조사하였는데 길항균주의 항생물질 생산에 미치는 탄소원의 영향은 0.45% N-acetyl-D-glucosamine과 0.15% D(+) cellobiose에서 81%와 89%의 P. capsicivh자의 성장 억제율을 나타냈다. 질소원의 경우는 0.55% $NH_4$CI 첨가시 69%의 억제율을 나타냈고 무기염의 영향에 있어서는 0.01% KCI을 사용했을 때 63%의 억제율을 나타냈다. 또한 배양 조건에 있어서는 pH 7.0m $30^{\circ}C$에서 84시간 배양시 가장 높은 항진균성 항생물질 생산성을 나타내었다. 토양내에서 실제로 생물방제력을 발휘하는지를 확인하기 위하여 고추를 이용한 in vivo pot test를 실시한 결과 P capsici 만 처리한 것은 고추역병 현상을 나타냈고, P capsici 와 길항균 C luteola 5042를 함께 처리한 것은 역병 현상이 나타나지 않았다. 이것으로 길항균주는 C luteola 5042 P capsici 의 성장을 저해하여 고추 역병의 발병을 억제한다는 사실을 확인할수 있었다.

• Nuclear Engineering and Technology
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• 제38권5호
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• pp.399-404
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• 2006

Noninvasive molecular targeting in living subjects is highly demanded for better understanding of such diverse topics as the efficient delivery of drugs, genes, or radionuclides for the diagnosis or treatment of diseases. Progress in molecular biology, genetic engineering and polymer chemistry provides various tools to target molecules and cells in vivo. We used chitosan as a polymer, and $^{99m}Tc$ as a radionuclide. We developed $^{99m}Tc-galactosylated$ chitosan to target asialoglycoprotein receptors for nuclear imaging. We also developed $^{99m}Tc-HYNIC-chitosan-transferrin$ to target inflammatory cells, which was more effective than $^{67}Ga-citrate$ for imaging inflammatory lesions. For an effective delivery of molecules, a longer circulation time is needed. We found that around 10% PEGylation was most effective to prolong the circulation time of liposomes for nuclear imaging of $^{99m}Tc-HMPAO-labeled$ liposomes in rats. Using various characteristics of molecules, we can deliver drugs into targets more effectively. We found that $^{99m}Tc-labeled$ biodegradable pullulan-derivatives are retained in tumor tissue in response to extracellular ion-strength. For the trafficking of various cells or bacteria in an intact animal, we used optical imaging techniques or radiolabeled cells. We monitored tumor-targeting bacteria by bioluminescent imaging techniques, dentritic cells by radiolabeling and neuronal stem cells by sodium-iodide symporter reporter gene imaging. In summary, we introduced recent achievements of molecular nuclear imaging technologies in targeting receptors for hepatocyte or inflammatory cells and in trafficking bacterial, immune and stem cells using molecular nuclear imaging techniques.

• 대한의용생체공학회:의공학회지
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• 제37권5호
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• pp.186-194
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• 2016

In this study, a co-axial flow induced microfluidic chip to fabricate pure collagen type I microfiber via the control of collagen type I and Na-alginate gelation process. The pure collagen type I microfiber was generated by selective degradation of Ca-alginate from 'Core-Shell' structured hydrogel microfiber. To make 'Core-Shell' structure, collagen type I solution was introduced into core channel and 1.5% Na-alginate solution was injected into side channel in microfluidic chip. To evaluatethe 'Core-Shell' structure, the red and green fluorescence substances were mixed into collagen type I and Na-alginate solution, respectively. The fluorescence substances were uniformly loaded into each fiber, and the different fluorescence images were dependent on their location. By immoblizing EpH4-Ras and C6 cells within collagen type I and Na-alginate solution, we sucessfully demonstrated the co-culture of EpH4-Ras and C6 cells with 'Core-Shell' like hydrogel microfiber for 5 days. Only to produce pure collagen type I hydrogel fiber, tri-sodium citrate solution was used to dissolve the shell-like Ca-alginate hydrogel fiber from 'Core-Shell' structured hydrogel microfiber, which is an excellent advantage when the fiber is employed in three-dimensional scaffold. This novel method could apply various application in tissue engineering and biomedical engineering.

• 한국미생물·생명공학회지
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• 제17권1호
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• pp.74-80
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• 1989

광합성 세균의 수소생성 향상을 위한 노력의 일환으로 수소생성능이 좋은 Rhodopseudomonas E15-1 을 고정화하여 수소생성에 적당한 조건을 조사하였다. 담체로 4%의 alginate를 사용하였을 때 수소생성량이 많았으며 고정화함에 따라 산소. 질소에 대한 억제효과를 덜 받았다. Alginate 고정화 세포는 그 지름을 2mm 이하로 하는 것이 겔내로의 확산저항이 적으므로 적당했다. 여러가지 유기물을 활용하여 수소를 생성할 수 있었으며 특히 citrate, fumarate와 malate 같은 유기산의 경우 30mM의 농도가 수소생성에 있어서 적당하였다. 또한 고정화세포를 이용한 계속적인 수소생성에 있어서 20일부터 활성이 감소하기는 하나 겔의 구조적 안정성은 30일까지 유지되었다.

• Journal of Nutrition and Health
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• 제34권7호
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• pp.734-740
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• 2001

The purpose of this study was to investigate the effect of green tea catechins on the antioxidative defense enzyme activity of kidney in diabetic rats. Sprague-Dawley male rats weighting 100$\pm$10g were randomly assigned to one normal and three STZ-induced diabetic groups; catechin free diet(DM-0C group), 0.25% catechin diet(DM-0.25C group) and 0.5% catechin diet(DM-0.5C group). Diabetes was induced by intravenous of 55mg/Kg body weight of STZ in sodium citrate buffer(pH 4.3) after 4 weeks feeding of experimental diets. Rats were sacrified at the 6th day of diabetic states. Superoxide dismutase(SOD) activity in kidney was decreased by 25% and 20% in DM-0C and DM-0.25C groups compared with normal group, DM-0.5C group was not significantly different when compared with normal group. Glutathione peroxidase(GSHpx) activity in kidney was were no significant differences the diabetic groups compared to normal group. Xanthin oxidase(XOD) activity was increased by 110% and 63% in DM-0C and DM-0.25C groups compared with normal group, DM-0.5C group was not significantly different when compared with normal group. The contents of superoxide radical(O$_2$)in kindney were 116% and 33%, respectively, higher in DM-0C and DM-0.25C groups than normal group. DM-0.5C group and normal groups were similar levels in their superoxide radical contents of kidneys. Levels of TBARS(thiobarbituric acid reactive substance) in kidney were increased by 62% in DM-0C group, when compared with normal group, but those of DM-0.5C group were similar to that of normal groups. These results indicate that free radical generation system was weakened and free radical scavenger system was enhance in kidney of STZ-induced diabetics rats by dietary catechin. Thereby it may reduce renal disorders such as oxidative damage and aging of tissue.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.34.2-34.2
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• 2011

The demand for Ru has been increasing in the electronic, chemical and semiconductor industry. Chemical mechanical planarization (CMP) is one of the fabrication processes for electrode formation and barrier layer removal. The abrasive particles can be easily contaminated on the top surface during the CMP process. This can induce adverse effects on subsequent patterning and film deposition processes. In this study, a post Ru CMP cleaning solution was formulated by using sodium periodate as an etchant and citric acid to modify the zeta potential of alumina particles and Ru surfaces. Ru film (150 nm thickness) was deposited on tetraethylorthosilicate (TEOS) films by the atomic layer deposition method. Ru wafers were cut into $2.0{\times}2.0$ cm pieces for the surface analysis and used for estimating PRE. A laser zeta potential analyzer (LEZA-600, Otsuka Electronics Co., Japan) was used to obtain the zeta potentials of alumina particles and the Ru surface. A contact angle analyzer (Phoenix 300, SEO, Korea) was used to measure the contact angle of the Ru surface. The adhesion force between an alumina particle and Ru wafer surface was measured by an atomic force microscope (AFM, XE-100, Park Systems, Korea). In a solution with citric acid, the zeta potential of the alumina surface was changed to a negative value due to the adsorption of negative citrate ions. However, the hydrous Ru oxide, which has positive surface charge, could be formed on Ru surface in citric acid solution at pH 6 and 8. At pH 6 and 8, relatively low particle removal efficiency was observed in citric acid solution due to the attractive force between the Ru surface and particles. At pH 10, the lowest adhesion force and highest cleaning efficiency were measured due to the repulsive force between the contaminated alumina particle and the Ru surface. The highest PRE was achieved in citric acid solution with NaIO4 below 0.01 M at pH 10.