• Macromolecular Research
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• v.14 no.2
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• pp.146-154
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• 2006

Organic and inorganic hybrid nanocomposites based on poly(ethylene 2,6-naphthalate) (PEN) and silica nanoparticles were prepared by a melt blending process. In particular, polymer nanocomposites consisting mostly of cheap conventional polyesters with very small quantities of inorganic nanoparticles are of great interest from an industrial perspective. The crystallization behavior of PEN/silica hybrid nanocomposites depended significantly on silica content and crystallization temperature. The activation energy of crystallization for PEN/silica hybrid nanocomposites was decreased by incorporating a small quantity of silica nanoparticles. Double melting behavior was observed in PEN/silica hybrid nanocomposites, and the equilibrium melting temperature decreased with increasing silica content. The fold surface free energy of PEN/silica hybrid nanocomposites decreased with increasing silica content. The work of chain folding (q) for PEN was estimated as $7.28{\times}10^{-20}J$ per molecular chain fold, while the q values for the PEN/silica 0.9 hybrid nanocomposite was $3.71{\times}10^{-20}J$, implying that the incorporation of silica nanoparticles lowers the work required to fold the polymer chains.

• IMMUNE NETWORK
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• v.12 no.3
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• pp.104-112
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• 2012

Silica is one of the most abundant compounds found in nature. Immoderate exposure to crystalline silica has been linked to pulmonary disease and crystalline silica has been classified as a Group I carcinogen. Ultrafine (diameter <100 nm) silica particles may have different toxicological properties compared to larger particles. We evaluated the effect of ultrafine silica nanoparticles on mouse bone marrow-derived dendritic cells (BMDC) and murine dendritic cell line, DC2.4. The exposure of dendritic cells (DCs) to ultrafine silica nanoparticles showed a decrease in cell viability and an induction of cell death in size- and concentration-dependent manners. In addition, in order to examine the phenotypic changes of DCs following co-culture with silica nanoparticles, we added each sized-silica nanoparticle along with GM-CSF and IL-4 during and after DC differentiation. Expression of CD11c, a typical DC marker, and multiple surface molecules such as CD54, CD80, CD86, MHC class II, was changed by silica nanoparticles in a size-dependent manner. We also found that silica nanoparticles affect inflammatory response in DCs in vitro and in vivo. Finally, we found that p38 and NF-${\kappa}B$ activation may be critical for the inflammatory response by silica nanoparticles. Our data demonstrate that ultrafine silica nanoparticles have cytotoxic effects on dendritic cells and immune modulation effects in vitro and in vivo.

• Physical Therapy Korea
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• v.17 no.4
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• pp.1-7
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• 2010

The aim of this study was to investigate the effects of lumbar stabilization on both trunk and lower limb muscle activity and center of pressure (COP) in single leg standing. Surface electromyography (EMG) was used to collect muscle activity data, the mean velocity of COP was measured using a force plate, and a pressure biofeedback unit was used for lumbar stabilization training. The findings of this study are summarized as follows: 1) The EMG activity of the erector spinae decreased significantly and the activity of the rectus abdominis, internal oblique, external oblique, gluteus maximus, and gluteus medius increased significantly with lumbar stabilization single leg standing. 2) No differences in activity in the tibialis anterior, medial gastrocnemius, rectus femoris, and medial hamstrings were found with single leg standing. 3) The mean velocity of COP in the antero-posterior and medio-lateral directions in the lumbar stabilization single leg standing decreased significantly compared with the preferred single leg standing. The findings of this study therefore indicate that lumbar stabilization can facilitate the co-activation of deep stabilization and global muscles that improve postural control capability during single leg standing.

• Journal of the Korean Ceramic Society
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• v.24 no.6
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• pp.543-552
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• 1987

The effects of deposition variables on SnO2 CVD were investigated for SnCl4＋O2 reaction at 300∼700$^{\circ}C$, Psncl4=1${\times}$10-5∼1${\times}$10-3 atm, and Po2=5${\times}$10-4∼1 atm. A thermodynamic equilibrium study on Sn-Cl-O system has been performed with the computer calculation. The calculation indicates that major species participating the reaction in SnCl4 and not intermediate species, SnCl2. Good uniformity of the film thickness was obtained at the flow rate of 11cm/sec, which resulted from the stable gas flow in our cold wall reactor. The experimental results showed that apparent activation energy of the deposition was about 13.5Kcal/mole below the temperature of 500$^{\circ}C$ and the deposition mechanism was controlled by surface reation. The behavior of deposition rate on the reactant partial pressures could be explained with the Langmuri-Hinshelwood mechanism. X-ray study demonstrated that SnO2 film deposited at temperatures above 400$^{\circ}C$ were polycrystalline with tetragonal rutile structure and grew with (211) and (301) preferred orientations.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.19 no.2
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• pp.55-60
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• 2013

Background: The purpose of this study was to determine if there is a difference in activation of the rectus femoris, vastus medialis oblique, vastus lateralis, semitendinosus, and biceps femoris when performing normal free squat with standinding position and free squat with $30^{\circ}$ flexed hip joint. Methods: Electromyograph surface electrodes were placed on the rectus femoris, vastus medialis oblique, vastus lateralis, semitendinosus, and biceps femoris of 19 healthy college students. The participants performed standing bilateral squats and standing bilateral squats with $30^{\circ}$ flexed hip joint with EMG measures taken upon initiation of muscle activity as confirmed by an electronic goniometer. Participants completed one trial with the EMG time measurements on each type. Results: There was a significant difference between normal squats(standing squats) and normal squats with $30^{\circ}$ flexed hip joint. The normal squat exercise was statistically higer than normal squat exercise with $30^{\circ}$ flexed trunk except for semitendinosus and biceps femoris that shown slightly high. Conclusions: As a result of this study, there were increases of muscle activity in both ways. In particular, it may be more beneficial for knee joint stabilization to perform normal squat exercise with standing position relatively.

• Journal of Electrochemical Science and Technology
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• v.8 no.3
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• pp.215-221
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• 2017

The electroless plating process largely consists of substrate cleaning, seed formation (activator formation), and electroless plating. The most widely used activator in the seed formation step is Pd, and Sn ions are used to facilitate the formation of this Pd seed layer. This is problematic because the Sn ions interfere with the reduction of Cu ions during electroless plating; thus, the Sn ions must be removed by a hydrochloric acid cleaning process. This method is also expensive due to the use of Pd. In this study, Cu electroless plating was performed by forming a seed layer using a silver nanosol instead of Pd and Sn. The effects of the Ag nanosol concentration in the pretreatment solution and the pretreatment time on the thickness and surface morphology of the Cu layer were investigated. The degrees of adhesion to the substrate were similar for the electroless-plated Cu layers formed by conventional Pd activation and those formed by the Ag nanosol.

• Biomedical Science Letters
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• v.14 no.3
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• pp.199-201
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• 2008

Eosinophil is an improtant leukocyte in the development of various inflammatory diseases. Monocyte chemoattractant protein-1 (MCP-1) acts as a key regulator on monocyte movement, and activation of T cells and NK cells. However, the role of MCP-1 in eosinophils remains to be solved. In the present study, we examined the effect of MCP-1 on eosinophil migration, using human eosinophilic EoL-1 cells as an in vitro model of eosinophils. The surface expression of CCR2 in EoL-1 cells was little detected but MCP-1 strongly induced EoL-1 cell migration in a dose-dependent manner. Increased chemotactic activity due to MCP-1 was blocked by pertussis toxin, a $G_i/G_o$ protein inhibitor and U73122, a phospholipase C (PLC) inhibitor. These results suggest that MCP-1 activates $G_i/G_o$ protein and PLC and this signal pathway is involved in eosinphil movement. This finding supports the elucidation of pathogenic mechanism of eosinophilic inflammation such as asthma and atopic dermatitis.

• BMB Reports
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• v.48 no.11
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• pp.624-629
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• 2015

Lysozyme protects us from the ever-present danger of bacterial infection and binds to bacterial lipopolysaccharide (LPS) with high affinity. Beyond its role in the activation of protein C, the endothelial cell protein C receptor (EPCR) plays an important role in the cytoprotective pathway. EPCR can be shed from the cell surface, which is mediated by tumor necrosis factor-α converting enzyme (TACE). However, little is known about the effects of lysozyme on EPCR shedding. We investigated this issue by monitoring the effects of lysozyme on phorbol-12-myristate 13-acetate (PMA)-, tumor necrosis factor (TNF)-α-, interleukin (IL)-1βand cecal ligation and puncture (CLP)-mediated EPCR shedding and underlying mechanism. Data demonstrate that lysozyme induced potent inhibition of PMA-, TNF-α-, IL-1β-, and CLP-induced EPCR shedding. Lysozyme also inhibited the expression and activity of PMA-induced TACE in endothelial cells. These results demonstrate the potential of lysozyme as an anti-EPCR shedding reagent against PMA-mediated and CLP-mediated EPCR shedding.

• PNF and Movement
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• v.15 no.3
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• pp.381-387
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• 2017

Purpose: Although some studies indicate that the Sorensen test may not be used to examine back muscles such as the erector spinae, alternatives to the back-extension test are rarely suggested. Therefore, the purpose of the present study was to investigate an effective way to stimulate the erector spinae muscles by adding a component of trunk rotation and lateral bending to general back extensions. Methods: A total of 18 healthy, physically active participants performed simple trunk extension, extension with trunk rotation, and extension with lateral bending. Surface electromyography responses of the latissimus dorsi, thoracic, and lumbar levels of the erector spinae; the gluteus maximus; and the biceps femoris muscles were investigated during these 3 conditions of modified back extension tests. Results: The simple trunk extension exercise caused significant increases in activity of the gluteus maximus and biceps femoris muscles as compared to the extension with rotation and lateral bending exercises. The extension with trunk rotation exercise showed significantly greater activation in the thoracic and lumbar levels of the erector spinae and in the latissimus dorsi as compared to the other exercises. The index measuring subjective difficulty was significantly lower in the simple trunk extension exercise as compared to the extension with trunk rotation and extension with lateral bending exercises. Conclusion: The present study suggests that extension with trunk rotation has the advantage of stimulating the para-spinal muscles, while simple trunk extension may not be adequate to selectively simulate the para-spinal muscles but may be appropriate for examining global trunk extensors.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2000.04a
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• pp.17-19
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• 2000

Heterotrimeric G Proteins transduce ligand binding to a wide variety of seven transmembrane cell surface receptors into intracellular signals. The currently accepted model for the activation of G protein suggests that ligand-activated receptor accelerates GDP-GTP exchange reactions on the ${\alpha}$ subunit of the heterotrimeric G protein. At least seventeen distinct isoforms of the G${\alpha}$ subunit protein have been identified in mammalian organisms. Among them, the G${\alpha}$q family consists of five members whose ${\alpha}$ subunits show different expression patterns. G${\alpha}$q and G${\alpha}$11 seem to be almost ubiquitously expressed, whereas G${\alpha}$14 is predominantly expressed in spleen, lung, kidney and testis. G${\alpha}$16 and its murine counterpart G${\alpha}$15 are expressed in hematopoietic cells and has been shown to couple a wide variety of receptors to phosphoinositide-specific phospholipase C activity. Beta-isoforms of phospholipase C were shown to be activated by all members of G${\alpha}$q family, i.e., G${\alpha}$q, G${\alpha}$11, G${\alpha}$l4 and G${\alpha}$16 subunits either in reconstitution system. or in experiments using cDNA transfection with intact Cos-7 cells.