바이폴라막은 양이온교환층과 음이온교환층 및 양극접합층으로 이루어진 이온교환막으로 물 분해 특성을 기반으 로 하여 프로톤과 수산화 이온을 생성시키는 막이다. 이러한 특성을 이용하여 화학 산업, 식품 가공, 환경 보호, 에너지 변환 및 저장과 같은 다양한 응용 분야에서 연구가 되고 있다. 본 논문에서는 바이폴라막 기술에 대한 종합적인 이해를 제공하기 위해 바이폴라막의 개념 및 물 분해 메커니즘과 물 분해 촉매에 대한 조사하였다. 마지막으로 최근 에너지 기술에 적용되고 있는 바이폴라막 프로세스를 조사하였다.

Intermuscular fat is essential for enhancing the flavor and texture of cultured meat. Mesenchymal stem cells derived from intermuscular adipose tissues are a source of intermuscular fat. Therefore, as a step towards developing a platform to derive intermuscular fat from mesenchymal stem cells (MSCs) for insertion between myofibrils in cultured beef, an advanced protocol of intermuscular adipose tissue dissociation effective to the isolation of MSCs from intermuscular adipose tissues was developed in cattle. To accomplish this, physical steps were added to the enzymatic dissociation of intermuscular adipose tissues, and the MSCs were established from primary cells dissociated with physical step-free and step-added enzymatic dissociation protocols. The application of a physical step (intensive shaking up) at 5 minutes intervals during enzymatic dissociation resulted in the greatest number of primary cells derived from intermuscular adipose tissues, showed effective formation of colony forming units-fibroblasts (CFU-Fs) from the retrieved primary cells, and generated MSCs with no increase in doubling time. Thus, this protocol will contribute to the stable supply of good quality adipose-derived mesenchymal stem cells (ADMSCs) as a fat source for the production of marbled cultured beef.

To predict the long-term behaviors of actinides in aqueous environments, complexation behaviors of actinides should be understood. Various organic ligands of chelating aromatic structure appearing in humic substances are known to form stable aqueous complexes. In this study, a benzene diol (or catechol) derivative, i.e., 4-nitrocatechol (nCA) is selected and its chemical equilibria including acid dissociation and complexation with U(VI) ion were examined using spectroscopic methods. In addition, the effect of ionic strength (Is) on those equilibria was evaluated by adjusting the level of NaClO4 in aqueous solutions. First, the experiments to determine the acid dissociation constant (pKa) of nCA were carried out in aqueous solutions with different ionic strengths from 0.01–2.0 M. The acid dissociation constants of nCA (pKa1) were measured to 6.73 ± 0.07, 6.69 ± 0.03, 6.38 ± 0.03, 6.09 ± 0.12, and 6.04 ± 0.07 at Is = 0.01, 0.1, 0.5, 1.0, and 2.0, respectively. These results were confirmed through the UV-Vis absorption spectral data analysis using the HypSpec program. As the pKa1 decreases as the ionic strength increases, except for Is = 2.0, these data were further analyzed with SIT (Specific ion Interaction Theory). Typically, as the solution becomes basic, a red shift is shown in the absorption spectrum. This effect can be understood from the intramolecular charge transfer (ICT) occurring in the deprotonated structures of nCA. At higher pH similar trends were also observed for measurement of pKa2. However, the determination of pKa2 is found not to be straightforward since a dimer formation equilibrium of nCA was observed as the ionic strength increased. This phenomenon will be discussed in detail with other supporting experimental results. Second of all, the complexation between the U(VI) and nCA in aqueous solutions was also examined. It was shown that nCA can easily form complexes with U(VI) ions at a wide range of pH via the deprotonation of their hydroxyl groups. U(VI)-nCA complexation will be further characterized by UV-Vis spectroscopy, IR and NMR by varying the solution ionic strength. The metal-ligand binding stoichiometry will be confirmed, for example, through the Job’s method. Finally, the acid dissociations constant and stability constants that were determined in this study will be used to provide species diagrams of aqueous U(VI)-nCA systems at a wide range of pH considering the effect of solution ionic strengths.

Induced pluripotent stem cells (iPSCs) can be generated from adult cells. Somatic cells can be reprogrammed to form iPSCs by overexpressing transcription factors such as Oct4, Sox2, cMyc, and Klf4. To maintain undifferentiated state of iPSCs in vitro, cells have traditionally been maintained on mouse embryonic fibroblast feeders and passaged by enzymatic or mechanical dissociation methods. In this study, we compared the morphology and pluripotency of porcine iPSCs (piPSCs) after subsequent passaging using enzymatic and mechanical dissociation methods. Enzymatically and mechanically passaged piPSCs showed embryonic stem cell-like morphologies with compact cell adhesion and clear colony borders. In addition, alkaline phosphatase staining was positive for both enzymatically and mechanically passaged piPSCs. However, visual observation revealed that some colonies of enzymatically passaged piPSCs were spontaneously differentiated more than those of piPSCs mechanically passaged from 5 passage. Quantitative real-time RT-PCR demonstrated that enzymatically and mechanically passaged piPSCs expressed pluripotent genes such as Oct4, Sox2 and Nanog well at early passage. Immunofluorescent staining also confirmed that pluripotent markers such as Oct4, Sox2, and Nanog were positively expressed at early passage. However, expression levels of pluripotent genes in mechanically passaged piPSCs were also higher than those in enzymatically passaged piPSCs at early passage. Collectively, we found that mechanical passage method was better than enzymatic passage in terms of morphology and pluripotency of piPSCs at early passage. Further studies are needed to compare these dissociation methods with those obtained after more passages of piPSCs.

Adsorption of a water molecule on a Si (001) surface and its dissociation were studied using density functional theory to study the distribution of -OH fragments on the Si surface. The Si (001) surface was composed of Si dimers, which buckle in a zigzag pattern below the order-disorder transition temperature to reduce the surface energy. When a water molecule approached the Si surface, the O atom of the water molecule favored the down-buckled Si atom, and the H atom of the water molecule favored the up-buckled Si atom. This is explained by the attractions between the negatively charged O of the water and the positively charged down-buckled Si atom and between the positively charged H of the water and the negatively charged up-buckled Si atom. Following the adsorption of the first water molecule on the surface, a second water molecule adsorbed on either the inter-dimer or intra-dimer site of the Si dimer. The dipole-dipole interaction of the two adsorbed water molecules led to the formation of the water dimer, and the dissociation of the water molecules occurred easily below the order-disorder transition temperature. Therefore, the 1/2 monolayer of -OH on the water-terminated Si (001) surface shows a regular distribution. The results shed light on the atomic layer deposition process of alternate gate dielectric materials, such as HfO2.

Human embryonic stem (ES) cells are a potential source of cells for developmental studies and for a variety of applications in transplantation therapies and drug discovery. However, human ES cells are difficult to culture and maintain at a large scale, which is one of the most serious obstacles in human ES cell research. Culture of human ES cells on MEF cells after disassociation with accutase has previously been demonstrated by other research groups. Here, we confirmed that human ES cells (H9) can maintain stem cell properties when the cells are passaged as single cells under a feeder-free culture condition. Accutase-dissociated human ES cells showed normal karyotype, stem cell marker expression, and morphology. We prepared frozen stocks during the culture period, thawed two of the human ES cell stocks, and analyzed the cells after culture with the same method. Although the cells revealed normal expression of stem cell marker genes, they had abnormal karyotypes. Therefore, we suggest that accutase-dissociated single cells can be usefully expanded in a feeder-free condition but chromosomal modification should be considered in the culture after freeze-thawing.

The purpose of this work was to examine whether X-Y chromosome dissociation in the primary spermatocytes of mice could be used as an in vivo short-term assaying system that detect environmental mutagens. Four alkylating agents(EMS, MMS, MMC and MNNG) which were known as strong mutagens were administered to BALB/c male mice 3-4 months old. In the control group, the mean frequencies of previously dissociated X and Y chromosomes and autosomes were 7.17% and 2.12%, respectively. Compared to the control group, mutagen-treated groups have no significant differences in dissociation rate of autosomes, while these groups were about 1.2-2.5 times higher in the frequencies of X-Y dissociation. Generally, X-Y dissociation frequency increased consistently with the concentration of mutagens whereas the tendency of autosome dissociation frequency was variable among several mutagens. These results suggest that X-Y dissociation in the primary spermatocytes of mice is applicable as an in vivo short-term assaying system for environmental mutagens. There were significantly distinct increase in dissociation of X-Y chromosome in both the hybrid and parents but the X-Y previous dissociation of hybrid appeared higher frequency than BALB/c and wild mice. These results indicate that the factor related to binding X-Y chromosome is specific to strains.