• Clean Technology
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• v.24 no.3
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• pp.157-165
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• 2018

In this study, the removal of $Si_3N_4$ particles from the surface of a silicon wafer was investigated by using supercritical carbon dioxide, the IPA co-solvent and cleaning additive chemicals. First, the solubility of several surfactants and binders in supercritical carbon dioxide solubility and particle dispersibility in the binders were evaluated in order to confirm their suitability for the supercritical cleaning process. Particle removal experiments were carried out with adjusting various process parameters and reaction conditions. The surfactants used in the experiment showed little particle removal effect, producing secondary contamination on the surface of wafers. On the other hand, 5 wt% (with respect to $scCO_2$) of the cleaning additive mixture of trimethyl phosphate, IPA, and trace HF resulted in 85% of particle removal efficiency after $scCO_2$ flowing for 4 minutes at $50^{\circ}C$, 2000 psi, and the flow rate of $15mL\;min^{-1}$.

• Polymer(Korea)
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• v.38 no.2
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• pp.164-170
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• 2014

This study was designed to find an appropriate biomaterial to proliferate Schwann cell (SC). Poly(lactic-co-glycolic acid) (PLGA) films mixed with demineralized bone particle (DBP), small intestine submucosa (SIS), and silk were fabricated by a solvent casting method. Analysis of MTT, SEM and RT-PCR were performed to confirm adhesion and proliferation of SC. Contact angle of films was assayed for hydrophilicity of films. We confirmed that PLGA/DBP 20% film showed higher hydrophilicity, promoted adhesion and proliferation of SC than other films. It was concluded that PLGA/DBP film can be applied for the scaffold biomaterials for the regeneration of central nerve system.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.433-437
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• 2006

Pt/Nafion self-humidifying membranes for Polymer Electrolyte Membrane Fuel Cell(PEMFC) were synthesized via supercritical-impregnation methods. The Nafion 112 membranes were impregnated with Pt(II)$(acetylacetonate)_2$ from a supercritical carbon dioxide $(scCO_2)$ solution at $80^{\circ}C$ and 30MPa. After the impregnation, the pressure decreased slowly by releasing $CO_2$. And the Pt-impregnated Nafion membrane was converted Pt deposited Nafion membrane by reducing agent, sodium borohydride $(NaBH_4)$ with various concentrations under $50^{\circ}C$ and 2 hours. The prepared Pt-impregnated Nafion (Pt/Nafion) composite membrane were investigated by Electron Prove Micro analysis (EPMA) and X-rat Diffraction analysis (XRD) which showed distribution of Pt particle and Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) a which revealed morphology of surface of Pt/Nafion composite membrane. The performance of the Pt/Nafion 112 membranes was examined in PEMFC as aself-humidifyin membranes using purpose-built equipment.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1449-1454
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• 2014

The co-sensitization of N719 with a cyclic thiourea functionalized organic dye, coded AZ5, for dye-sensitized solar cells (DSSCs) was demonstrated. Due to its intensive absorption in ultraviolet region, AZ5 could compensate the loss of light harvest induced by triiodide, thereby the short-circuit photocurrent density ($J_{sc}$) was increased for co-sensitized (N719+AZ5) DSSC. Moreover, the electron recombination and dye aggregation were retarded upon N719 cocktail co-sensitized with AZ5, thus the open-circuit voltage ($V_{oc}$) of co-sensitized device was enhanced as well. The increased $J_{sc}$ (17.9 $mA{\cdot}cm^{-2}$) combined with the enhanced $V_{oc}$ (698 mV) ultimately resulted in an improved power conversion efficiency (PCE) of 7.91% for co-sensitized DSSC, which was raised by 8.6% in comparison with that of N719 (PCE = 7.28%) sensitized alone. In addition, co-sensitized DSSC exhibited a better stability than that of N719 sensitized device probably due to the depression of dye desorption.

• Journal of Animal Science and Technology
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• v.62 no.6
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• pp.893-902
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• 2020

This study was conducted to compare the mRNA expression levels of myogenic-adipogenic makers in the skeletal muscle and adipocytes formation, body weight, rumen weight, and papilla length on Hanwoo calves at newborn and 6 months of age. Animals used three newborn Hanwoo calves (NC) and three Hanwoo calves 6 months of age (SC). Body weight and rumen weight were significantly increased in SC compared to NC (p < 0.01), and papilla length was longer about 10-fold in SC than NC. Adipocytes was possible to visually identify more adipocytes in SC compared to NC, and were mainly formed around the blood vessels. mRNA expression of myogenin, myosin heavy chain 1 and myosin heavy chain 2A in both longissimus dorsi (LD) and semimembranosus (SM) was found to increase with calves growth (p < 0.01), and it was confirmed that have higher levels of mRNA expression in SM than LD. In LD tissues, the mRNA expression of stearoyl-CoA desaturase (SCD, p < 0.03) and peroxisome proliferator activated receptor γ (PPARγ, p < 0.04) was significantly higher in SC than NC. In SM tissues, mRNA expression levels of SCD (p < 0.02) and CCAAT/enhancer binding protein β (C/EBPβ, p < 0.01) were higher in SC than NC, and also mRNA expression levels of PPARγ increased, but there was no significant difference. Thus, the calves period suggests that it is an important step in the development of the rumen and the myogenesis and adipogenesis.

• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.113-117
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• 1993

Good yield synthetic routes for the production of new B-alkyl-dithiaborane clusters are reported. The syntheses of the B-alkyl-dithiaboranes are based on the use of Fischer-type carbene reagents to activate the B-H bonds of dithiaborane for alkyl-addition reactions and are the first examples of transition-mediated reactions of dithiaborane to be reported. Thus, reactions employing arachno-$S_2B_7H_8$- and $(CO)_5M{C(R_1)R_2}$ (M = Cr, W; $R_1 = CH_3,\;C_6H_5;\; R_2 = OCH_3,\;SC_6H_5)$ were found to yield the intermidiate anions I, $[(CO)_5M{C(R_1)R_2S_2B_7H_8}]^-$, which upon protonation gave the corresponding neutral, air-sensitive cluster arachno-4-$RCH_2-6,8-S_2B_7H_8(R=CH_3,\;IIa;\;C_6H_5,\;IIb)$ range from 30 to 35% yield. Complexes IIa and IIb are isoelectronic with arachno-6,8-$S_2B_7H_9$ and, on the basis of the spectroscopic data, are proposed to adopt a similar arachno cage geometry in which an $RCH_2$ units are substituted to 4 position boron atom of the arachno-6,8-$S_2B_7H_9$.

• Polymer(Korea)
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• v.37 no.6
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• pp.685-693
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• 2013

The foams of a poly(lactic acid) modified by the reactive compounding were produced with the batch foaming technique using supercritical $CO_2(scCO_2)$. Experiments were performed at $105{\sim}135^{\circ}C$ and 12~24 MPa. The blowing ratio and foam structure were significantly affected by changing the temperature and pressure conditions in the foaming process. The blowing ratio first increased with increasing foaming temperature and saturation pressure, reached a maximum and then decreased with a further increase in the foaming temperature and saturation pressure. Decreasing the rate of depressurization permitted a longer period of cell growth and therefore larger microcellular structures were obtained.

• Journal of Microbiology and Biotechnology
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• v.29 no.10
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• pp.1644-1655
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• 2019

Saccharomyces cerevisiae (S. cerevisiae) and glucagon-like peptide-2 (GLP-2) have been employed to improve the intestinal development of weaned animals. The goal of this study was to determine whether either exogenous S. cerevisiae or GLP-2 elicits major effects on fecal microbiotas and cytokine responses in weaned piglets. Ninety-six piglets weaned at 26 days were assigned to one of four groups: 1) Basal diet (Control), 2) empty vector-harboring S. cerevisiae (EV-SC), 3) GLP-2-expressing S. cerevisiae (GLP2-SC), and 4) recombinant human GLP-2 (rh-GLP2). At the start of the post-weaning period (day 0), and at day 28, fecal samples were collected to assess the bacterial communities via sequencing the V1-V2 region of the 16S-rRNA gene, and piglets' blood was also sampled to measure cytokine responses (i.e., IL-$1{\beta}$, TNF-${\alpha}$, and IFN-${\gamma}$). This study revealed that, on the one hand, although S. cerevisiae supplementation did not significantly alter the growth of weaned piglets, it induced increases in the relative abundances of two core genera (Ruminococcaceae_norank and Erysipelotrichaceae_norank) and decreases in the relative abundances of two other core genera (Lachnospiraceae_norank and Clostridiale_norank) and cytokine levels (IL-$1{\beta}$ and TNF-${\alpha}$) (p < 0.05, Control vs EV-SC; p < 0.05, rh-GLP2 vs GLP2-SC). On the other hand, GLP-2 supplementation had no significant influence on fecal bacterial communities and cytokine levels, but it produced better body weight and average daily gain (p < 0.05, Control vs EV-SC; p < 0.05, rh-GLP2 vs GLP2-SC). Therefore, altered fecal microbiotas and cytokine response effects in weaned piglets were due to S. cerevisiae rather than GLP-2.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2006.04a
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• pp.95-96
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• 2006

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2005.11a
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• pp.156-157
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• 2005