• Membrane Journal
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• v.14 no.3
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• pp.201-206
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• 2004

The stability of the prepared silica membrane by chemical vapor deposition (CVD) method in the HI-$H_2O$ gaseous mixture was evaluated aiming at the application for hydrogen iodide decomposition in the thermochemical IS process. Porous $\alpha$-alumina having pore size of 100 nm was modified by the different CVD temperature using tetraethoxysilane as the Si source. The CVD temperature was $700^{\circ}C$, $650^{\circ}C$, and $600^{\circ}C$. The $H_2$/H$_2$ selectivities of the modified membranes which were measured by single-component permeation experiment showed 43.2, 12.6, and 8.7 at $600^{\circ}C$ for the M1 (CVD temperature was $700^{\circ}C$), M2 (CVD temperature was $650^{\circ}C$) and M3 membranes (CVD temperature was $600^{\circ}C$), respectively. Stability experiment in the HI-$H_2O$ gaseous mixture was carried out at $450^{\circ}C$. The prepared silica membrane at $600^{\circ}C$ of CVD temperature was more stable than that at the other CVD temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.3
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• pp.228-233
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• 2001

This paper presents the optimized design, fabrication and thermal characteristics of micro-heaters for thermal MEMS (micro elelctro mechanical system) applications usign SOI (Si-on-insulator) and trench structures. The micro-heater is based on a thermal measurement principle and contains for thermal isolation regions a 10㎛ thick Si membrane with oxide-filled trenches in the SOI membrane rim. The micro-heater was fabricated with Pt-RTD (resistance thermometer device) on the same substrate by suing MgO as medium layer. The thermal characteristics of the micro-heater wit the SOI membrane is 280$\^{C}$ at input power 0.9W; for the SOI membrane with 10 trenches, it is 580$\^{C}$ due to reduction of the external thermal loss. Therefore, the micro-heater with trenches in SOI membrane rim provides a powerful and versatile alternative technology for improving the performance of micro-thermal sensors and actuators.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.2
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• pp.115-121
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• 2009

Functional defects in mitochondria are involved in the induction of cell death in cancer cells. We assessed the toxic effect of camptothecin against the human cervical and uterine tumor cell line SiHa with respect to the mitochondria-mediated cell death process, and examined the combined effect of camptothecin and anticancer drugs. Camptothecin caused apoptosis in SiHa cells by inducing mitochondrial membrane permeability changes that lead to the loss of mitochondrial membrane potential, decreased Bcl-2 levels, cytochrome c release, caspase-3 activation, formation of reactive oxygen species and depletion of GSH. Combination of camptothecin with other anticancer drugs (carboplatin, paclitaxel, doxorubicin and mitomycin c) or signaling inhibitors (farnesyltransferase inhibitor and ERK inhibitor) did not enhance the camptothecin-induced cell death and caspase-3 activation. These results suggest that camptothecin may cause cell death in SiHa cells by inducing changes in mitochondrial membrane permeability, which leads to cytochrome c release and activation of caspase-3. This effect is also associated with increased formation of reactive oxygen species and depletion of GSH. Combination with other anticancer drugs (or signaling inhibitors) does not appear to increase the anti-tumor effect of camptothecin against SiHa cells, but rather may reduce it. Combination of camptothecin with other anticancer drugs does not seem to provide a benefit in the treatment of cervical and uterine cancer compared with camptothecin monotherapy.

• Korean Membrane Journal
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• v.3 no.1
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• pp.69-74
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• 2001

Films of TiO$_2$/SiO$_2$ were deposited on the inner surface of the porous glass support tubes by decomposition of tetraisopropyl titanate (TIPT) and tetraethyl orthosilicate (TEOS) at atmospheric pressure. Dense and hydrogen -permselective membranes were formed at 400-600$\^{C}$. The permeation rates of H$_2$ through the membrane at 600$\^{C}$ were 0.2-0.4 ㎤(STP)/min-㎠ atm and H$_2$:N$_2$permeation ratios were above 1000. The permeation properties of the membranes were investigated at various deposition temperatures and TIPT/TEOS concentrations. Decomposition of TIPT alone at temperatures above 400$\^{C}$ produced porous crystalline TiO$_2$ films and they were not H7-selective. Decomposition of TEOS produced H$_2$-permeable SiO$_2$ films at 400-600$\^{C}$ but film deposition rate was very low. Addition of TIFT to the TEOS stream significantly accelerated the deposition rate and produced highly H$_2$-selective films. Increasing the TIPT/TEOS concentration ratio increased the deposition rate. The TiO$_2$/SiO$_2$ membranes formed at 600 $\^{C}$ have the permeation properties comparable to those of SiO$_2$ membranes produced from TEOS.

• Membrane Journal
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• v.16 no.4
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• pp.268-275
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• 2006

Novel SILEMs were prepared by multi-stage phase separation process combined by the low temperature phase separation (LTPS) and the high temperature phase separation (HTPS) using room temperature ionic liquids (RTILs) which have a high ionic conductivity. PVDF and imidazolium series ionic liquids were used as membrane material and electrolyte, respectively. To study the ion conducting properties, the SILEMs were tested using LCR meter at temperature controlled from 30 to $130^{\circ}C$. Under humid conditions, with increasing temperature from 30 to $100^{\circ}C$, the ion conductivity of the cast $Nafion^{(R)}$ membrane increased linearly, but then started to decrease after $100^{\circ}C$. However, in the case of the SILEMs, with increasing operating temperature, the ion conductivity increased. Also, the ion conductivity behaviors of the SILEMs were almost same, regardless of humidity. The ion conductivity of the SILEMs was $2.7{\times}10^{-3}S/cm$ and increased almost linearly up to $2.2{\times}10^{-2}S/cm$ with increasing temperature to $130^{\circ}C$. The effects of an inorganic filler on the physical properties of the SILEMs were studied using the $SiO_2$. The addition of $SiO_2$ could improve the mechanical strength of the SILEMs, though the ionic conductivity was decreased slightly.

• Journal of Energy Engineering
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• v.20 no.3
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• pp.171-177
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• 2011

PVA/GLA/$Al_2O_3{\cdot}3SiO_2$ composite membranes were prepared through the reaction polyvinyl alcohol (PVA) with glutaraldehyde (GLA) as a cross-linking agent and subsequently adding aluminum silicate ($Al_2O_3{\cdot}3SiO_2$) as an inorganic material. The water uptake decreased as the GDL contents increased due to cross-linking process of PVA with GDL, and the ion conductivity increased as the $Al_2O_3{\cdot}3SiO_2$ contents increased in PVA/GLA/$Al_2O_3{\cdot}3SiO_2$ composite membranes. The cross-linking structure of the polymers was confirmed using IR and the tendency of water uptake. The thermal analysis of the copolymers was carried out by TGA. TGA results showed that PVA/GLA composite membrane were more heat-resistant than PVA due to the cross-linking of PVA, and the heat stability of the composite membranes improved much more as the concentration of $Al_2O_3{\cdot}3SiO_2$ increased. Membranes prepared in this study seem to be have thermal stability and increase a tendency of the cation conductivity up to $60^{\circ}C$, but to be exhibit lower performance tendency at over $90^{\circ}C$. Therefore, it is necessary to do more aggressive effort to explore the possibility of application as an ion-conductive composite electrolyte.

• Membrane Journal
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• v.25 no.2
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• pp.115-122
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• 2015

$SiO_2{\cdot}B_2O_3$ was prepared by trimethylborate (TMB)/tetraethylorthosilicate (TEOS) mole ratio 0.01 at $800^{\circ}C$. PDMS[poly(dimethysiloxane)]-$SiO_2{\cdot}B_2O_3$ composite membranes were prepared by adding porous $SiO_2{\cdot}B_2O_3$ to PDMS. To investigate the characteristics of PDMS-$SiO_2{\cdot}B_2O_3$ composite membrane, we observed PDMS-$SiO_2{\cdot}B_2O_3$ composite membrane using TG-DTA, FT-IR, BET, X-ray, and SEM. PDMS-$SiO_2{\cdot}B_2O_3$ composite membrane was studied on the permeabilities of $H_2$ and $N_2$ and the selectivity ($H_2/N_2$). Following the results of TG-DTA, BET, X-ray, FT-IR, $SiO_2{\cdot}B_2O_3$ was the amorphous porous $SiO_2{\cdot}B_2O_3$ with $247.6868m^2/g$ surface area and $37.7821{\AA}$ the mean of pore diameter. According to the TGA measurements, the thermal stability of PDMS-$SiO_2{\cdot}B_2O_3$ composite membrane was enhanced by inserting $SiO_2{\cdot}B_2O_3$. SEM observation showed that the size of dispersed $SiO_2{\cdot}B_2O_3$ in the PDMS-$SiO_2{\cdot}B_2O_3$ composite membrane was about $1{\mu}m$. The increasing of $SiO_2{\cdot}B_2O_3$ content in PDMS leaded the following results in the gas permeation experiment: the permeability of both $H_2$ and $N_2$ was increased, and the permeability of $H_2$ was higher than $N_2$, but the selectivity($H_2/N_2$) was decreased.

• Journal of Sensor Science and Technology
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• v.4 no.3
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• pp.51-59
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• 1995

Stress-balanced flat 150 nm-$Si_{3}N_{4}$/300 nm-$SiO_{2}$/150 nm-$Si_{3}N_{4}$ dielectric membrane on silicon substrate has been fabricated. Analyses of stress-deflection and stress-temperature, and visual inspection for the strain diagnostic test patterns were performed in order to characterize stress properties of the membrane. The $SiO_{2}$ layers sandwiched between two $Si_{3}N_{4}$ layers were deposited by three different techniques(PECVD, LPCVD, and APCVD) for the purpose of investigating the dependence of stress on the deposition methods. Some extent of tensile stress in the membrane was always observed regardless of the deposition methods, however it could be balanced against silicon substrate by post-wet oxidation in $1,150^{\circ}C$. Stress-temperature characteristics of the membranes showed that APCVD-LTO was better as mid-$SiO_{2}$ layer than PECVD - or LPCVD - $SiO_{2}$ when there was no oxidation process.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.6
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• pp.573-580
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• 2004

The main goal of this study was to develop a micro-fabrication process for the capacitive micromachined ultrasonic transducer (cMUT). In order to achieve this goal, the former research results of the micro-electro-mechanical system (MEMS) process for the cMUT were analyzed. The membrane deposition, sacrificial layer deposition and etching were found to be a main process of fabricating the cMUT. The optimal conditions for those microfabrication were determined by the experiment. The thickness, uniformity, and residual stress of the $Si_3N_3$ deposition which forms the membrane of the cMUT were characterized after growing the $Si_3N_3$ on Si-wafer under various process conditions. As a sacrificial layer, the growth rate of the $SiO_2$ deposition was analyzed under several process conditions. The optimal etching conditions of the sacrificial layer were analyzed. The microfabrication process developed in this study will be used to fabricate the cMUT.

• Membrane Journal
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• v.9 no.2
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• pp.97-106
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• 1999

A and 2SM-5 type zeoli tic crystal films were synthesized on porous supports from the reaction mixture of 1.9 ${SiO}_2$1.5 $Na_20-Al_2O_3-40$ $H_20$ and $Si0_2$-0.l3 $Na_2O$-52 $H_20$-O.l2 TPAOH composition, respectively. The zeolite films were characterized by XRD and SEM. The 2SM -5 crystals grown on the porous matrix were very closely bound together. It was so difficult to obtain the perfectly intergrown crystals in the case of A-type zeolite and this crystal was transformed into P-type zeolite membrane with a prolonged reaction time. The densely intergrown A type zeolite crystal membrane could be also synthesized by the hydrothermal treatment at 100$^{\cirt}C$ after pressing the reaction mixture without addition of water. The pervaporation performance of the synthesized porous inorganic membranes was investigated for alcohol and water mixtures. A-type zeolite membrane crystallized as a thin film showed the selective \'Jermeability of water from the mixtures through the molecular sieving activity of micropores.