• Proceedings of the Membrane Society of Korea Conference
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• 1995.04a
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• pp.1-4
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• 1995

The microstructure of polymer membranes produced via thermally induced phase separation (TIPS) of polymer solutions is a strong function of both the early-stage (by spinodal decomposition or nucleation & growth) and the late-stage phase separation (referred to in general as coarsening). In the case of early stage effects, the membrane morphology resulting from a nucleation & growth mechanism is either a poorly interconnecsed, stringy, beady structure which is mechanically fragile or a well interconnected structure with highly nonuniform pore sizes. In contrast, spinodal decomposition results in a well interconnected, mechanically strong membrane with highly uniform pore sizes. Here I describe recent quantitative studies of the coarsening effects on the microstructure of membranes produced via TIPS process. The dependence of microstructure on coarsening time, quench depth, solution viscosity, and polymer molecular weight was investigated in order to distinguish among three possible coarsening mechanisms, Ostwald ripening, coalescence, and hydrodynamic flow, which may be responsible for structural evolution after the early-stage phase Separation (spinodal decomposition or nucleation & growth).

• Molecules and Cells
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• v.46 no.2
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• pp.74-85
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• 2023

Single-cell research has provided a breakthrough in biology to understand heterogeneous cell groups, such as tissues and organs, in development and disease. Molecular barcoding and subsequent sequencing technology insert a single-cell barcode into isolated single cells, allowing separation cell by cell. Given that multimodal information from a cell defines precise cellular states, recent technical advances in methods focus on simultaneously extracting multimodal data recorded in different biological materials (DNA, RNA, protein, etc.). This review summarizes recently developed single-cell multiomics approaches regarding genome, epigenome, and protein profiles with the transcriptome. In particular, we focus on how to anchor or tag molecules from a cell, improve throughputs with sample multiplexing, and record lineages, and we further discuss the future developments of the technology.

• Membrane Journal
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• v.14 no.4
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• pp.298-303
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• 2004

PTMSP/PDMS-PEI composite membrane was prepared by solution casting method. To investigate the characteristics of this membrane, the analytical methods such as FT-IR, $^1$H-NMR, DSC, TGA, GPC, and SEM have been utilized. The number-average((equation omitted)) and weight-average((equation omitted)) molecular weight of PTMSP/PDMS copolymer were 501,516 and 675,560 respectively. The separation of the gas mixture($H_2$/$N_2$) through the composite membrane was studied as a function of pressure. The separation factor($\alpha$, $\beta$, (equation omitted)) of the composite membrane used in this work increased as the pressure of permeation cell increased. The real separation factor($\alpha$), head separation factor($\beta$), and tail separation factor ((equation omitted)) of PTMSP/PDMS-PEI composite membrane were 21.50, 49.14 and 1.84 respectively at $\Delta$P 345.55 kPa and $25^{\circ}C$.

• Membrane Journal
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• v.15 no.2
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• pp.105-113
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• 2005

Silica membranes were prepared on a porous metal sheet by ultrasonic spray pyrolysis method for gas separation at high temperatures. In order to improve the permselectivity, silica was deposited in the sol-gel derived $silica/\gamma-alumina$ intermediate layer by pyrolysis of tetraethyl orthosilicate (TEOS) at 873 K. The pyrolysis with forced cross flow through the porous wall of the support was very effective in plugging mesopores, Knudsen diffusion regime, that were left unplugged in the membranes. At permeation temperature of 523 K, the silica/alumina composite membrane showed $H_2/N_2$ and water/methanol selectivity as high as 17 and 16, respectively, by molecular sieve effect.

• Membrane Journal
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• v.13 no.4
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• pp.291-299
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• 2003

Polymer membranes such as poly(1-trimethylsilyl-1-propyne)-polyetherimide (PTMSP-PEI) and poly(dimethylsiloxane)- polyetherimide (PDMS-PEI) composite membrane were prepared by solution casting method. To investigate the characteristics of these membranes, the analytical methods such as FT-IR, $^1H-NMR,$ DSC, TGA, GPC, and SEM have been utilized. The number-average (equation omitted) and weight-average (equation omitted) molecular weight of PTMSP were 477,920 and 673,329 respectively. The glass transition temperature ($T_g$) of PTMSP was $224^{\circ}C.$ The separation of the gas mixture ($H_2/N_2$) through the composite membranes were studied as a function of pressure. The separation factor (${\alpha}, {\beta},$ quation omitted) of the composite membranes used in this work increased as the pressure of permeation cell increased. The real separation factor (${\alpha}$), head separation factor (${\beta}$), and tail separation factor (equation omitted) of PTMSP-PEI composite membrane were 2.28, 1.17, and 1.96 respectively at ${\Delta}P$ 30psi and $25^{\circ}C.$ (${\alpha}, {\beta}$ and equation omitted of PDMS-PEI composite membrane were 3.70, 1.53, and 2.42 respectively at ${\Delta}P$ 30psi and $25^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.687-693
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• 2004

Composite membranes with a titania layer were prepared by soaking-rolling method with the titania sol of nanoparticles formed in the sol-gel process and investigated regarding the vapor permeation of various organic mixtures. The support modification was conducted by pressing $SiO_2$ xerogel of 500 nm in particle size under 10 MPa on the surface of a porous stainless steel (SUS) substrate and designed the multi-layered structure by coating the intermediate layer of ${\gamma}-Al_2O_3$. Microstructure of titania membrane was affected by heat-treatment and synthesis conditions of precursor sol, and titania formed at calcination temperature of 300$^{\circ}C$ with sol of [$H^+$]/[TIP]=0.3 possessed surface area of 210 $m^2$/g, average pore size of 1.25 nm. The titania composite membrane showed high $H_2/N_2$ selectivity and water/ethanol selectivity as 25-30 and 50-100, respectively. As a result of vapor permeation for water-alcohol and alcohol-alcohol mixture, titania composite membrane showed water-permselective and molecular-sieve permeation behavior. However, water/methanol selectivity of the membrane was very low because of chemical affinity of permeants for the membrane by similar physicochemical properties of water and methanol.

• Analytical Science and Technology
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• v.19 no.6
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• pp.529-534
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• 2006

The protein separation with molecular weight using SDS-PAGE(sodium dodecyl sulfate-polyacrylamide gel electrophoresis) is the one of the most conventional and simple techniques. In, this study, two dimensional SDS-PAGE using same separation principle consecutively was investigated and compared with one dimensional SDS-PAGE. The enhanced separation from duplex SDS-PAGE was observed and separated proteins in the gel were identified by MALDI TOF MS. Identified proteins from different gel spots were found to have different gi numbers. Therefore, duplex SDS-PAGE separation method will be used for economic separation method in the future because only tiny amount of inexpensive reagents are used to perform duplex SDS-PAGE.

• Elastomers and Composites
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• v.43 no.3
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• pp.191-198
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• 2008

It is said that polymer modified asphalt using polyethylene as modifier would show phase separation due to density difference and incompatibility between asphalt and polyethylene. In this study, to prevent coalescence of polyethylene in asphalt, we employed peroxides as phase separation inhibitor. On microscope, peroxides (dicumyl peroxide, lauroyl peroxide) with waste vinyl (comprising low density polyethylene) did not show phase separation, however, rheometer test showed phase separation at molecular level, i.e., polyethylene and asphalt are immiscible ultimately. Mechanical properties (tensile strength, Marshall stability, dynamic stability) showed waste vinyl-modified asphalts are highly resistant to plastic deformation and these properties are even better than those of Superphalt.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.169-171
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• 2004

• Proceedings of the Membrane Society of Korea Conference
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• 2003.11a
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• pp.200-203
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• 2003