• Bulletin of the Korean Chemical Society
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• v.24 no.3
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• pp.325-333
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• 2003

An analysis of the electronic structure and bonding in the ternary silicide YNiSi₃is made, using extended Huckel tight-binding calculations. The YNiSi₃structure consists of Ni-capped Si₂dimer layers and Si zigzag chains. Significant bonding interactions are present between the silicon atoms in the structure. The oxidation state formalism of $(Y^{3+})(Ni^0)(Si^3)^{3-}$ for YNiSi₃constitutes a good starting point to describe its electronic structure. Si atoms receive electrons from the most electropositive Y in YNiSi₃, and Ni 3d and Si 3p states dominate below the Fermi level. There is an interesting electron balance between the two Si and Ni sublattices. Since the ${\pi}^*$ orbitals in the Si chain and the Ni d and s block levels are almost completely occupied, the charge balance for YNiSi₃can be rewritten as $(Y^{3+})(Ni^{2-})(Si^{2-})(Si-Si)^+$, making the Si₂layers oxidized. These results suggest that the Si zigzag chain contains single bonds and the Si₂double layer possesses single bonds within a dimer with a partial double bond character. Strong Si-Si and Ni-Si bonding interactions are important for giving stability to the structure, while essentially no metal-metal bonding exists at all. The 2D metallic behavior of this compound is due to the Si-Si interaction leading to dispersion of the several Si₂π bands crossing the Fermi level in the plane perpendicular to the crystallographic b axis.

• Proceedings of the Korean Magnetic Resonance Society Conference
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• 2002.08a
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• pp.90-90
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• 2002

Syndecans, transmembrane heparan sulfate proteoglycans, are coreceptors with integrin in cell adhesion process. It forms a ternary signaling complex with protein kinase C and phosphatidylinositol 4,5 bisphosphate (PIP2) for integrin signaling. NMR data indicates that cytoplasmic domain of syndecan-4 (4L) undergoes a conformational transition in the presence of PIP2, forming oligomeric conformation. The structure based on NMR data demonstrated that syndecan-4L itself forms a compact intertwined symmetric dimer with an unusual clamp shape for residues Leu$^{186}$ -Ala$^{195}$ . The molecular surface of the syndecan-4L dimer is highly positively charged. In addition, no inter-subunit NOEs in membrane proximal amino acid resides (Cl region) has been observed, demonstrating that the Cl region is mostly unstructured in syndecan-4L dimmer. However, the complex structure in the presence of PIP2 induced a high order multimeric conformation in solution. In addition, phosphorylation of cytoplasmic domain induces conformational change of syndecan-4, resulting inhibition of PKC signaling. The NMR structural data strongly suggest that PIP2 promotes oligomerization of syndecan-4 cytoplasmic domain for PKC activation and further induces structural reorganization of syndecan for mediating signaling network in cell adhesion procedure.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.5 s.113
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• pp.1-7
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• 2005

The objective of this work was to investigate the effect of spreading behavior of the sizing agents (AKD or dialkyl ketone) on the sizing development of AKD-sized paper. There was a direct relationship between the spreading behavior of the sizing agents and their melting points. Both AKD and dialkyl ketone showed no substantial spreading until the temperature reaches to their melting points. Consequently, dialkyl ketone did not provide sizing development when the paper was heat-treated below $75^{\circ}C$, while AKD provided sizing effect even the paper heated at $50^{\circ}C$. The ketone, however, provided rather higher sizing effect than that of AKD, when the paper was heat-treated over $100^{\circ}C$. This result means that the ketone also gives sizing development to paper, moreover the ketone could give higher sizing effect to paper than AKD when it was melted and well spreaded on the fiber surface. While the ketone introduced to papers from hydrolyzed AKD emulsion could not contribute to sizing development.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2000.11a
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• pp.83-83
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• 2000

Alkylketene dimer was known as a cellulose reactive or alkaline size because it does not require to fix to the fiber as do the traditional rosin sizes. A proposed sizing mechanism of AKD was the formation of P -ketoester bond between AKD and cellulose which provides the permanent attachment and the orientation of the hydrophobic alkylchains outward. However, some questions about the reaction had arisen and thus, the sizing mechanism of AKD has been a subject of controversy for several decades. The major concern of the controversy is that AKD is really reactive with cellulose or not in the papermaking conditions. In this study, reaction between AKD and pulp fiber was investigated, in order to find out whether AKD forms P-ketoester with pulp fiber during aging under no catalyzed neutral condition with obvious spectroscopic evidence. In addition, effect of aging treatment on the sizing development was studied. It has been disclosed that, in absence of water, AKD reacted with cellulose to form P -ketoester linkage under no catalyzed neutral condition, while, in presence of water, most of AKD was hydrolyzed to a dialkyl ketone or P -ketoacid. In addition, during the aging treatment of AKD-sized paper, its typical IR spectra bands gradually were reduced, completely disappeared after 6hr aging, and formed new absorption bands at 1707cm-' and shoulder peak at 1700cm-' which refer to the typical dialkylketone absorption bands. Therefore, the formation of P -ketoester between AKD and pulp fiber is impossible in the practical papermaking process. It could be suggested that the sizing development of AKD-sized paper is obtained by next two mechanism: 1) formation of a thin-layer of AKD on the fiber surface through melting and spreading of AKD emulsion particles by heat and 2) the hydrolysis of AKD to dialkyl ketone which has higher melting point, during drying and storage of AKD sized papers.

• Journal of Trauma and Injury
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• v.26 no.3
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• pp.74-80
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• 2013

Purpose: There are no detailed reports on the incidence of venous thromboembolism (VTE) in pelvic and acetabular fractures in the Asian population. The purpose of this study was to investigate the incidence of VTE in pelvic and acetabular fractures in the Korean population. Methods: The cases of 67 Korean patients with pelvic and acetabular fractures treated at our hospital from January 2009 to February 2012 were analyzed retrospectively. Until May 2010, VTE screening was performed by contrast-enhanced computed tomography (CT) or ultrasonography (US) when the D-dimer value did not decline predictably, still exceeded $20{\mu}g/ml$ at 5 days after trauma and surgery, or increased to greater than $20{\mu}g/ml$ after a period of decline. After May 2010, contrast-enhanced CT and US were performed routinely irrespective of the D-dimer value. Physical prophylaxis was performed on all patients. The effects of the presence of a pelvic and/or acetabular fracture, and the effects of fracture type, accompanying injuries, and screening strategies on the incidences of VTE were investigated. Results: Overall, 26 patients(38.8%) were diagnosed with VTE and PTE in 14(20.9%). All were asymptomatic. Significantly higher incidences of VTE and PTE were observed in trauma patients with pelvic and acetabular fractures than in trauma patients without pelvic and acetabula fractures treated during the same period. No significant differences were observed in the incidences of VTE and PTE between patients with pelvic fractures, and patients with acetabular fractures or between patients with and without accompanying injuries. Compared with the previous screening strategy, the detection rates for VTE and PTE were higher for the newer screening strategy; however, the difference did not reach statistical significance. Conclusion: In the Korean population, we should be vigilant for a high incidence of VTE, especially PTE, in patients with pelvic and acetabular fractures.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.2
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• pp.24-29
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• 1998

This study was carried out in order to elucidate the deterioration mechanism of paper according to various sizing chemicals. No additive paper and four kinds of papers containing rosin-alum, alum only, alkylketene dimer(AKD)-cation polymer and cation polymer only were treated by UV light to study changes of water-resistant, optical and mechanical properties from the view points of natural deterioration of paper. Since rosin chemicals have UV absorption at the relatively long wavelength region, rosins are degraded to form hydrophilic groups such as carboxylic acid from their double bonds by UV treatments. These phenomena caused the decreasing of sizing degree and wetting time in case of rosin-sized paper, while the UV treatments brought about the slight increase of wetting time in rosin-free papers such as no additive, alum and kymene only paper owing to the auto-sizing effect. Optical properties were primarily influenced by sizing chemicals. Rosin-sized paper showed lower brightness after UV and near UV treatment because of its UV instability.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.1
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• pp.83-90
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• 2017

Advanced age is one of the risk factors for vascular diseases that are mainly caused by impaired nitric oxide (NO) production. It has been demonstrated that endothelial arginase constrains the activity of endothelial nitric oxide synthase (eNOS) and limits NO generation. Hence, arginase inhibition is suggested to be vasoprotective in aging. In this study, we examined the effects of intravenous injection of Piceatannol, an arginase inhibitor, on aged mice. Our results show that Piceatannol administration reduced the blood pressure in aged mice by inhibiting arginase activity, which was associated with NO production and reactive oxygen species generation. In addition, Piceatannol administration recovered $Ca^{2+}$/calmodulin-dependent protein kinase II phosphorylation, eNOS phosphorylation and eNOS dimer stability in the aged mice. The improved NO signaling was shown to be effective in attenuating the phenylephrine-dependent contractile response and in enhancing the acetylcholine-dependent vasorelaxation response in aortic rings from the aged mice. These data suggest Piceatannol as a potential treatment for vascular disease.

• Biomedical Science Letters
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• v.10 no.4
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• pp.459-465
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• 2004

The use of hemofiltration has been proposed to reduce excessive body fluid and inflammatory mediators produced during cardiac surgery with cardiopulmonary bypass (CPB) in infants and children. This study was undertaken to evaluate the efficacy of hemofiltration in adult cardiac surgery using (CPB). Twenty adult patients scheduled for elective cardiac surgery were randomly assigned to control group without hemofiltration (n=10) or hemofilter group with hemofiltration during CPB (n=lO). CBC and serum levels of interleukin-6 (IL-6), D-dimer, endothelin-l (ET-1), and cortisol were measured at before the initiation and immediately after the termination of CPB (Pre-CPB and End-CPB, respectively). Clinical data were assessed at postoperative period. In hemofilter group hematocrit was significantly higher (30.04±2.63％ vs 23.30±2.71％, P=0.0014) whereas total leukocyte count was lower than in control group (7.71±1.78×10³/㎣ vs 16.01 ±3.12x10³/㎣, P=0.021) at End-CPB. Increased rate of IL-6 (311.56±97.31％ vs 825.45±102.56％, P=0.012) and D-dimer levels (154.55±89.04％ vs 308.33±157.64％, P=0.026) at End-CPB were significantly less in hemofilter group than in control group. Postoperative blood transfusion in hemofilter group was low compared with that of control group (741.00±38.07 ml vs 1,137.50±169.82 ml, P=0.037). There were no significant differences between two groups in platelet count, ET -1, cortisol, pulmonary index, mechanical ventilation, postoperative blood loss, ICU-stay and hospitalization. Hemofiltration technique applied in the present study provided partly beneficial effect in adult cardiac surgery.

• The Korean Journal of Zoology
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• v.25 no.2
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• pp.55-62
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• 1982

DNA synthesis, unscheduled DNA synthesis, excision of pyrimidine dimers and phtoreactivation were determined in UV-irradiated differentiating muscle cells at various times of primary culture of 12 day chick embryos and results obtained were as follows. The rates of UV-induced unscheduled DNA synthesis were increased as increase of UV dose. And the rates were gradually decreased as the increase of time after culture, but at higher doses the decreasing tendency was remarkable. The patterns of DNA replication were changed drastically as a function of time so that in the seven day cultures the rate of $^3$H-thymidine incorporation was found to be 0.2% of the original activity. The pattern of inhibition of DNA replication by UV damage demonstrated that in cells of earlier stages there were no remarkable changes, but in cells of later stages there was significant fluctuation. Photoreactivation and the excision of pyrimidine dimer in the one day cultures showed that photoreactivation occurred immediately after UV-irradiation, but excision of pyrimidine dimer was gradually and slowly occurred. These results indicate that the differentiation of embryonic muscle cells accompanies the gradual reduction of DNA replication and unscheduled DNA synthesis, and that the photoreactivation is rapid process compared to excision repair.

• Archives of Pharmacal Research
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• v.11 no.2
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• pp.93-98
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• 1988

To elucidate the reaction mechanism of ginseng protein on its antiradiation activity, its effects were studied on sister chromatid exchanges (SCE) induced by UV irradiation in CHO-KI cells. When cells were irradiated with 254 nm UV light at the dose of 0 to 8erg$\textrm{mm}^2$, the frequencies of CSE were increased more than two fold. However, when radio protective ginseng protein was added to the cells before the after UV irradiation, SCE frequencies were decreased significantly at all UV doses in both cases with no significant differences. As the amount of ginseng protein was varied from 100 to 500 .mu.g/ml, with UV irradiation at 60 erg$\textrm{mm}^2$, SCE frequencies dropped sharply at the first two concentrations and then reached a sort of plateau in both cases of pre-and post-treatment. When the ginseng protein was treated alone without UV irradiation, there were no changes in SCE frequencies no matter when the protein was added. There results suggest that the ginseng protein could reduced DNA damages, which may play an important role in the reaction mechanism of radioprotective activity of the protein.