• Fibers and Polymers
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• 제2권2호
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• pp.81-85
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• 2001

The effects of rate of phase separation to ester interchange reactions and the repulsive pair interaction energy on the phase behavior in a phase-separated immiscible polyester blend are investigated using a Monte Carlo simulation method. The time evolution of structure factor and the degree of randomness are monitored as a function of homogenization time. When the phase separation is dominant over ester interchange reactions, the domain size slowly increases with homogenization time. However, when the pair interaction becomes less repulsive, the domain size does not significantly change with homogenization time. On the other hand, when ester interchange reactions are dominant over the phase separation, the homogenization proceeds without a change in the domain size. The higher the extent of phase separation, the lower the increasing rate of the DR. However, when the phase separation is sufficiently dominant, the effect of the extent of phase separation on the increasing rate of the degree of randomness become less significant.

• Korean Chemical Engineering Research
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• 제54권1호
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• pp.57-63
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• 2016

Polyvinylidene fluoride (PVDF) 평막 제조를 위하여 PVDF의 용매와 희석제로서 n-methyl-2-pyrrolidone (NMP)와 dibutyl-phthlate (DBP)를 각각 사용하여 열유도 상분리(thermally induced phase separation, TIPS)와 비용매유도 상분리(nonsolvent induced phase separation, NIPS)를 동시에 유도하였다. NMP와 DBP를 PVDF와 용융 혼합할 경우 TIPS 공정에서의 결정화 온도가 낮아졌고 NIPS 공정에서의 불안정 영역이 확대되었다. 용매와 희석제의 비율에 따라 상분리 메카니즘이 변화하였고 이에 따라 다양한 구조의 막이 형성됨을 확인하였다. 또한 dope 용액과 비용매의 접촉여부에 따라 지배적인 상분리 거동이 결정되었다. 열전달이 물질전달에 비하여 빠르게 이루어지므로 막의 표면은 NIPS에 의하여 지배를 받고 막의 내부는 TIPS에 의한 구조가 형성되었다. 또한 dope 용액의 급냉온도에 따라 상분리 메카니즘 및 상분리 속도가 변화하여 다양한 구조를 형성하였다.

• 한국세라믹학회지
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• 제23권6호
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• pp.25-32
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• 1986

Phase spearated glass is heterogeneous in microscopic point of view and the heterogeneities affect the structures of glasses. In the present work the phase separation of $BaO-B_2O_3$ glass system was investigated and the effect of $P_2O_5$ on the phase separation and crystallization was also studied in the above system. Experiments such as scanning electron microscopy X-ray diffraction and infrared spectroscopy were performed. Phase separation with $B_2O_3$ rich phase matrix and BaO rich phase droplet was observed for the glasses containing less than 6 mole% of BaO while the opposite morphology of phase separation was found for the glasses containing more than 7 mole% of BaO. Phase separation region was extended up to the glass with 22mole% of BaO when the amount of $P_2O_5$ was increased. The heat-treated glasses crystallized to BaO.$4B_2O_3$$P_2O_5$ hindered the glass from the crystalli-zation.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권1호
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• pp.17-22
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• 2000

The separation of tryptophan enantiomers was carried out with medium-pressure liquid chromatography using BSA (bovine serum albumin)-bonded silica as a chiral stationary phase. The influence of various experimental factors such as pH and ionic strength of mobile phase, separation temperature, and the presence of organic additives on the resolution was studied. In order to expand this system to preparative scale, the loadability of sample and the stability of stationary phase for repeated use were also examined. The separation of tryptophan enantiomers was successful with this system. The data indicated that a higher separation factor (a) was obtained at a higher pH and lower temperature and ionic strength in mobile phase. Addition of organic additives (acetonitrile and 2-propanol) in mobile phase contributed to reduce the retention time of L-tryptophan. About $30\%$ of the separation factor was reduced after 80 days of repeated use.

• BMB Reports
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• 제55권8호
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• pp.363-369
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• 2022

Biomolecular phase separation has recently attracted broad interest, due to its role in the spatiotemporal compartmentalization of living cells. It governs the formation, regulation, and dissociation of biomolecular condensates, which play multiple roles in vivo, from activating specific biochemical reactions to organizing chromatin. Interestingly, biomolecular phase separation seems to be a mainly passive process, which can be explained by relatively simple physical principles and reproduced in vitro with a minimal set of components. This Mini review focuses on our current understanding of the fundamental principles of biomolecular phase separation and the recent progress in the research on this topic.

• 한국잠사곤충학회지
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• 제40권2호
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• pp.169-175
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• 1998

The morphology of silk fibroin/poly(vinyl alcohol)(PVA)blend films was investigated using optical microscopy and confocal laser scanning microscopy. The effects of blend ratio and molecular weight of silk fibroin and PVA on phase separation were studied. Macro-phase separation occurred for the silk fibroin-rich/poor region whereas micro-phase separation took place for the dispersed/continuous phase, In spite of differences in molecular weight and blend ratio, it is observed that the dispersed phase and continuous one are composed of silk fibroin and PVA component, respectively. As the molecular weight of silk fibroin and silk fibroin content in blend ratio are decreased, the compatibility of blend is increased due to the reduction of micro-phase separation.

• Molecules and Cells
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• 제45권1호
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• pp.6-15
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• 2022

Phase separation is a thermodynamic process leading to the formation of compositionally distinct phases. For the past few years, numerous works have shown that biomolecular phase separation serves as biogenesis mechanisms of diverse intracellular condensates, and aberrant phase transitions are associated with disease states such as neurodegenerative diseases and cancers. Condensates exhibit rich phase behaviors including multiphase internal structuring, noise buffering, and compositional tunability. Recent studies have begun to uncover how a network of intermolecular interactions can give rise to various biophysical features of condensates. Here, we review phase behaviors of biomolecules, particularly with regard to regular solution models of binary and ternary mixtures. We discuss how these theoretical frameworks explain many aspects of the assembly, composition, and miscibility of diverse biomolecular phases, and highlight how a model-based approach can help elucidate the detailed thermodynamic principle for multicomponent intracellular phase separation.

• Korean Membrane Journal
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• 제9권1호
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• pp.27-33
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• 2007

PVDF membrane formation via TIPS was performed for PVDF/DBP and PVDF/DMP systems. PVDF/DBP system showed solid-liquid phase separation behavior, while PVDF/DMP system has liquid-liquid phase separation characteristic as well as solid-liquid phase separation characteristic. PVDF contents and cooling conditions had great influence on structure, and the effects of each parameter were examined. Spherulitic structure was obtained due to the dominant PVDF crystallization. Diluent rejected to the outside of spherulite occupied the surface of the PVDF spherulites to result in the microporous spherulite formation and micro-void between spherulites. PVDF/DMP system had competitive solid-liquid and liquid-liquid phase separation depending on the cooling path.

• Nuclear Engineering and Technology
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• 제29권5호
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• pp.361-367
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• 1997

The phase separation in ferrite phase of duplex stainless steel is the primary cause of thermal aging embrittlement of the LWR primary pressure boundary components. In this study the phase separation of simulated duplex stainless steel was detected by Mossbauer spectroscopy and magnetic property analysis by VSM(Vibrating Specimen Magnetometer). The simulated duplex stainless steels, Fe-Cr binary, Fe-Cr-Ni ternary, and Fe-Cr-Ni-Si quarternary allots, were aged at 370 and 40$0^{\circ}C$ up to 5,340 hours. It was observed from Mossbauer spectra analysis that internal magnetic field increases with aging time and from VSM that the specific saturation magnetization and Curie temperature increase with aging time. These result are indicative that phase separation into Fe-rich region and Cr-rich region is caused by thermal aging in the temperature range of 370~40$0^{\circ}C$ In cases of specimens containing Ni, the increase of specific saturation magnetization is much higher. This implies that Ni seems to promote Fe-Cr interdiffusion, which accelerates the phase separation into Fe-rich $\alpha$ phase and Cr-rich $\alpha$' phase.

• 한국응용과학기술학회지
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• 제24권1호
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• pp.86-91
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• 2007

Gasohol, which is combined solution of gasoline and ethanol, is difficult to apply to the field, because it usually brings phase separation by mingling of water. We investigated phase separation by adding different concentrations of "Ethanol", anhydrous and fermentative, to "Gasolines", gasoline, gasoline base and naphtha, Placing ethanol itself open to the air, the concentrations of water are increased in length of time. The phase separation temperatures of the gasolines-ethanol solutions have dropped in the following order : gasoline, gasoline base and naphtha. When adding water to the solutions of gasolines and anhydrous ethanol, the temperatures of phase separation is higher when the concentration of water increases more. Thus, it is obvious that the water is sensitive in phase separation.