• Journal of environmental and Sanitary engineering
• /
• v.16 no.2
• /
• pp.91-99
• /
• 2001

Cross linked chitosan beads showed high selective adsorption abilities in order of $Au^{3+}$ > $Hg^{2+}$ > $Cu^{2+}$ > $Cd^{2+}$ > $Pt^{4+}$ > ${UO_2}^{2+}$ ions in mixed solution of various metal ions at pH 4.5. N-methyltyiobenzylated chitosan beads(MTB-chitosan beads) were prepared treating with p-(methylthio) benzaldehyde after cross linking of chitosan beads to give them a high selectivity in adsorption of metal ions. The MTB-chitosan beads demonstrated their selectivity on precious metals among various metal ions distinctively. Particularly, the MTB-chitosan had a peculiar selective adsorption on $Pd^{2+}$, $Au^{2+}$, and $Hg^{2+}$ions whilst the cross linked chitosan beads showed its high adsorption on $Pd^{2+}$ at pH 1.1. On the other hand, the cross linked chitosan beads showed its superiority in selective adsorption on $Au^{2+}$, $Cu^{2+}$, and $Hg^{2+}$ions to the MTB-chitosan at pH 4.5 of the test solution. Thus metal selectivities were given to chitosan beads through chemical modifications.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.10
• /
• pp.3005-3012
• /
• 2013

The effect of Mn-promotion on high surface area Al-pillared montmorillonite (AlMMT) supported Co nanoparticles prepared by hydrothermal method have been investigated. A series of different weight% Mn-promoted Co nanoparticles were prepared and characterized by XRD, TPR, TGA, BET and SEM techniques. An increase in the surface area of MMT is observed with Al-pillaring. Fischer-Tropsch catalytic activity of the as prepared catalysts was studied in a fixed bed micro reactor at $225^{\circ}C$, $H_2/CO$ = 2 and at 1 atm pressure. The data showed that by the addition of Mn the selectivity of $C_1$ dropped drastically while that of $C_2-C_{12}$ hydrocarbons increased significantly over all the Mn-promoted Co/AlMMT catalysts. The $C_{13}-C_{20}$ hydrocarbons remained almost same for all the catalysts while the selectivity of $C_{21+}$ long chain hydrocarbons decreased considerably with the addition of Mn. The catalyst with 3.5%Mn showed lowest $C_{21+}$ and highest $C_2-C_{12}$ hydrocarbons selectivity due to cracking of long chain hydrocarbons over acidic sites of MMT.

• Carbon letters
• /
• v.8 no.1
• /
• pp.12-16
• /
• 2007

Molecular sieving carbon (MSC) for separating $O_2-N_2$ and $CO_2-CH_4$ has been prepared through chemical vapor deposition (CVD) of methane and benzene on activated carbon spheres (ACS) derived from polystyrene sulfonate beads. The validity of the material for assessment of molecular sieving behavior for $O_2-N_2$ and $CO_2-CH_4$ pair of gases was assessed by the kinetic adsorption of the corresponding gases at $25^{\circ}C$. It was observed that methane cracking on ACS lead to deposition of carbon mostly in whole length of pores rather than in pore entrance, resulting in a reduction in adsorption capacity. MSC showing good selectivity for $CO_2-CH_4$ and $O_2-N_2$ separation was obtained through benzene cracking on ACS with benzene entrantment of $0.40{\times}10^{-4}\;g/ml$ at cracking temperature of $725^{\circ}C$ for a period of 90 minutes resulting in a selectivity of 3.31:1.00 for $O_2-N_2$ and 8.00:1.00 for $CO_2-CH_4$ pair of gases respectively.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.458-458
• /
• 2010

The process window for the etch selectivity of silicon nitride ($Si_3N_4$) layers to extreme ultra-violet (EUV) resist and variation of line edge roughness (LER) of EUV resist were investigated durin getching of $Si_3N_4$/EUV resist structure in a dual-frequency superimposed capacitive coupled plasma (DFS-CCP) etcher by varying the process parameters, such as the $CH_2F_2$ and $N_2$ gas flow rate in $CH_2F_2/N_2$/Ar plasma. The $CH_2F_2$ and $N_2$ flow rate was found to play a critical role in determining the process window for infinite etch selectivity of $Si_3N_4$/EUV resist, due to disproportionate changes in the degree of polymerization on $Si_3N_4$ and EUV resist surfaces. The preferential chemical reaction between hydrogen and carbon in the hydrofluorocarbon ($CH_xF_y$) polymer layer and the nitrogen and oxygen on the $Si_3N_4$, presumably leading to the formation of HCN, CO, and $CO_2$ etch by-products, results in a smaller steady-state hydrofluorocarbon thickness on $Si_3N_4$ and, in turn, in continuous $Si_3N_4$ etching due to enhanced $SiF_4$ formation, while the $CH_xF_y$ layer is deposited on the EUV resist surface. Also critical dimension (and line edge roughness) tend to decrease with increasing $N_2$ flow rate due to decreased degree of polymerization.

• Proceedings of the PSK Conference
• /
• 2003.10b
• /
• pp.94.2-94.2
• /
• 2003

CJ-11668 is a new potent and selective COX-2 inhibitor. CJ-11668 showed COX-2 inhibition (IC50) of 65nM and selectivity ratio (COX-l/COX-2) of 770 in the cell based assay. In the human whole blood assay, CJ-11668 showed COX-2 inhibition (IC50) of 370nM and selectivity ratio (COX-l/COX-2), 135. The treatment of CJ-11668 (5 mg/kg, p.o) produced a significant inhibition (35%) of inflamed rat paw volume in the carrageenan-induced acute inflammation. CJ-11668 also suppressed the PGE2 level (69% inhibition, 1 mg/kg, p.o) in the zymosan-induced mouse air pouch model after 3 hrs. (omitted)

• Applied Chemistry for Engineering
• /
• v.31 no.6
• /
• pp.679-687
• /
• 2020

In this study, poly(ether-block-amide) (PEBAX)/zeolitic imidazolate framework-8 (ZIF-8)-polyetherimide (PEI), and PEBAX/amine-modified ZIF-8 (amineZIF-8)-PEI composite membranes were prepared by varying the contents of ZIF-8 and amineZIF-8. Also the gas permeability properties of N2 and CO2 were investigated for each composite membrane. The N2 and CO2 permeability of the PEBAX/ZIF-8-PEI composite membrane increased as the ZIF-8 content increased, while the CO2/N2 selectivity gradually decreased. In the case of the PEBAX/amineZIF-8-PEI composite membrane, the permeability of N2 decreased slightly, and CO2 increased till amineZIF-8 amount was 0.5 wt% and then decreased when the content increased further. The CO2/N2 selectivity was the highest with a value of 78.3 at 0.5 wt% of amineZIF-8. because the amine modification in the amineZIF-8 improves the compatibility between PEBAX and amineZIF-8, It seems that amineZIF-8 was evenly dispersed in PEBAX, which could be greatly influenced by the porousity of ZIF-8 and also the affinity of amine toward CO2.

• Membrane Journal
• /
• v.14 no.2
• /
• pp.99-107
• /
• 2004

Carbon molecular sieve (CMS) membranes were prepared by pyrolysis of polyimides having carboxylic acid groups and applied to the hydrogen separation. The polymeric membranes having carboxylic acid groups showed different steric properties as compared with polymeric membranes having other side groups ($-CH_3$ and $-CF_3$) because of the hydrogen bond between the carboxylic acid groups. However, the microporous CMS membranes were significantly affected by the decomposable side groups evidenced from the wide angle X-rat diffraction, nitrogen adsorption isotherms, and single gas permeation measurement. Furthermore, the gas separation properties of the CMS membranes were essentially affected by the pyrolysis temperature. As a result, the CMS membranes Prepared by Pyrolysis of polyimide containing carboxylic acid froups at $700^{\circ}C$ showed the $H_2$ permeability of 3,809 Baller [$1{\times}10^{-10}$ H $\textrm{cm}^$(STP)cm/$\textrm{cm}^2$.s.cmHg], $H_2$/$N_2$, selectivity of 46 and $H_2$/$CH_4$ selectivity of 130 while the CMS membranes derived from polyimide showed the H$_2$ permeability of 3,272 Barrer, $H_2$/$N_2$ selectivity of 136 and $H_2$/$CH_4$ selectivity of 177.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.284-284
• /
• 2011

Recently, the increasing degree of device integration in the fabrication of Si semiconductor devices, etching processes of nano-scale materials and high aspect-ratio (HAR) structures become more important. Due to this reason, etch selectivity control during etching of HAR contact holes and trenches is very important. In this study, The etch selectivity and etch rate of TEOS oxide layer using ACL (amorphous carbon layer) mask are investigated various process parameters in CH2F2/C4F8/O2/Ar plasma during etching TEOS oxide layer using ArF/BARC/SiOx/ACL multilevel resist (MLR) structures. The deformation and etch characteristics of TEOS oxide layer using ACL hard mask was investigated in a dual-frequency superimposed capacitively coupled plasma (DFS-CCP) etcher by different fHF/ fLF combinations by varying the CH2F2/ C4F8 gas flow ratio plasmas. The etch characteristics were measured by on scanning electron microscopy (SEM) And X-ray photoelectron spectroscopy (XPS) analyses and Fourier transform infrared spectroscopy (FT-IR). A process window for very high selective etching of TEOS oxide using ACL mask could be determined by controlling the process parameters and in turn degree of polymerization. Mechanisms for high etch selectivity will discussed in detail.

• YAKHAK HOEJI
• /
• v.38 no.3
• /
• pp.345-350
• /
• 1994

Fourteen melandrin derivatives(I-XIV) were investigated on analgesic, anti-inflammatory and antiviral activities . Compound I [N-(p-hydroxybenzoyl)-5-hydroxyanthranilic acid methvl ester], Xll [N-(2-phenoxypropionyl)-5-hydroxy anthranilic acid propyl ester and XIV [N-(2-phenoxypropionyl)-5-hydroxyanthranilic acid exhibited analgesic activity in tail pressure and Randall-Selitto method. But no anti-inflammatory activity was shown. Compound I exhibited weak antiviral activity on Herpes simplex virus type I F strain by virus-induced cytopathic effect(CPE) assay and it's selectivity index(Sl) was 8.17.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2006.08a
• /
• pp.128-128
• /
• 2006