• Membrane Journal
• /
• v.28 no.4
• /
• pp.221-232
• /
• 2018

The silica containing carbon ($C-SiO_2$) membranes were fabricated using poly(imide siloxane)(Si-PI) and polyvinylpyrrolidone (PVP) blended polymer. The characteristics of porous carbon structures prepared by the pyrolysis of polymer blends were related with the micro-phase separation behaviors of the two polymers. The glass transition temperatures ($T_g$) of the mixed polymer blends of Si-PI and PVP were observed with a single $T_g$ using differential scanning calorimetry. Furthermore, the nitrogen adsorption isotherms of the $C-SiO_2$ membranes were investigated to define the characteristics of porous carbon structures. The $C-SiO_2$ membranes derived from Si-PI/PVP showed the type IV isotherm and possessed the hysteresis loop, which was associated with the mesoporous carbon structures. For the molecular sieving probe, the $C-SiO_2$ membranes were prepared with the ratio of Si-PI/PVP and the pyrolysis conditions, such as the pyrolysis temperature and the isothermal times. Consequently, the $C-SiO_2$ membranes prepared by the pyrolysis of Si-PI/PVP at $550^{\circ}C$ with the isothermal time of 120 min showed the $O_2$ permeability of 820 Barrer ($1{\times}10^{-10}cm^3(STP)cm/cm^2{\cdot}s{\cdot}cmHg$) and $O_2/N_2$ selectivity of 14.

• Proceedings of the Microbiological Society of Korea Conference
• /
• 2007.05a
• /
• pp.120-122
• /
• 2007

All living organisms use numerous signal-transduction pathways to sense and respond to their environments and thereby survive and proliferate in a range of biological niches. Molecular dissection of these signalling networks has increased our understanding of these communication processes and provides a platform for therapeutic intervention when these pathways malfunction in disease states, including infection. Owing to the expanding availability of sequenced genomes, a wealth of genetic and molecular tools and the conservation of signalling networks, members of the fungal kingdom serve as excellent model systems for more complex, multicellular organisms. Here, we employed Cryptococcus neoformans as a model system to understand how fungal-signalling circuits operate at the molecular level to sense and respond to a plethora of environmental stresses, including osmoticshock, UV, high temperature, oxidative stress and toxic drugs/metabolites. The stress-activated p38/Hog1 MAPK pathway is structurally conserved in many organisms as diverse as yeast and mammals, but its regulation is uniquely specialized in a majority of clinical Cryptococcus neoformans serotype A and D strains to control differentiation and virulence factor regulation. C. neoformans Hog1 MAPK is controlled by Pbs2 MAPK kinase (MAPKK). The Pbs2-Hog1 MAPK cascade is controlled by the fungal "two-component" system that is composed of a response regulator, Ssk1, and multiple sensor kinases, including two-component.like (Tco) 1 and Tco2. Tco1 and Tco2 play shared and distinct roles in stress responses and drug sensitivity through the Hog1 MAPK system. Furthermore, each sensor kinase mediates unique cellular functions for virulence and morphological differentiation. We also identified and characterized the Ssk2 MAPKKK upstream of the MAPKK Pbs2 and the MAPK Hog1 in C. neoformans. The SSK2 gene was identified as a potential component responsible for differential Hog1 regulation between the serotype D sibling f1 strains B3501 and B3502 through comparative analysis of their meiotic map with the meiotic segregation of Hog1-dependent sensitivity to the fungicide fludioxonil. Ssk2 is the only polymorphic component in the Hog1 MAPK module, including two coding sequence changes between the SSK2 alleles in B3501 and B3502 strains. To further support this finding, the SSK2 allele exchange completely swapped Hog1-related phenotypes between B3501 and B3502 strains. In the serotype A strain H99, disruption of the SSK2 gene dramatically enhanced capsule biosynthesis and mating efficiency, similar to pbs2 and hog1 mutations. Furthermore, ssk2, pbs2, and hog1 mutants are all hypersensitive to a variety of stresses and completely resistant to fludioxonil. Taken together, these findings indicate that Ssk2 is the critical interface protein connecting the two-component system and the Pbs2-Hog1 pathway in C. neoformans.

• Journal of Society of Preventive Korean Medicine
• /
• v.10 no.1
• /
• pp.141-153
• /
• 2006

In order to study the changes in hematology and serum chemistry of rats injected with glycerol, Sprague-Dawley albino rats weighing 240 to 260 gm were injected intramuscularly with a 50% solution of glycerol(8ml/kg). We measured the values of hematology and serum chemistry, and compared the measured values of S1 group(passed for 1day after injection of glycerol), S2 group(passed for 2days after injection of glycerol), S3 group(passed for 3days after injection of glycerol), S4 group(passed for 3days after injection of glycerol) and S5 group(passed for 4days after injection of glycerol) with those of Normal group(non-treated group). The results are summarized as follows : 1. In body temperature, S1, S2, S4 groups showed significantly higher compared with Normal group, especially S2 group was higher than S1 group(p<0.05). But S5 group was lower than Normal group(p<0.05). 2. In RBC, S1 group was lower than Normal group(p<0.05). And in Hct, S1, S2, S3 groups were lower than Normal group(p<0.05), in Hb, S1 and S3 groups were lower than Normal group(p<0.05). 3. In WBC, S1, S2 groups were higher than Normal group(p<0.05). and in WBC differential count, S2, S3, S5 groups were higher than N, S1, S4 groups in monocyte(p<0.05). 4. In GOT, S1 group was higher than Normal group(p<0.05), and S2, S3, S4, S5 groups were lower than S1 group(p<0.05). In GPT, S1 group was higher than Normal group(p<0.05), and S2, S3 groups were lower than S1 group(p<0.05), S4, S5 groups were lower than N, S1, S2, S3 groups(p<0.05). 5. In total cholesterol and creatinine, S4 group was higher than Normal group(p<0.05). According to the above experimental results, we could find the anemia, inflamation, damage of renal function for 4 days by intramuscularly injection with a 50% solution of glycerol(8ml/kg) in rat.

• Korean Journal of Plant Tissue Culture
• /
• v.26 no.3
• /
• pp.189-195
• /
• 1999

This study was carried out to clarify several factors affecting embryogenesis from anther culture of nine cultivars in Brassica oleracea L. var. italica and to investigate the characteristics of plants derived from anther culture. Androgenesis from anther culture was elevated on the B5 medium supplemented with 0.1mg/L NAA, 0.1mg/L 2.4-D and 10% sucrose. Embryo production in liquid medium was five-fold higher than solid medium. High temperature treatment at 35$^{\circ}C$ for one day before transfer to culture room maintained at $25^{\circ}C$ had effective to induce embryogenesis of cultured anthers but extended treatment at 35$^{\circ}C$ decreased significantly the percent of embryogenesis. Frequency of embryogenesis from cultured anthers exhibited significant difference from 2.8% in 'Green Valiant' to 21% in 'Haisi' as affected by genotypes. Percent of spontaneously dihaploid among regenerated plants from anther culture was ranged from 62 to 74% as affected by the genotypes. Characteristic in relation to plant height, number of leaves and branches, and size of head from anther-derived plants showed differential variation in 'Rokguray' and 'Haisi'. Among these charaters obtained from two cultivars, five lines were selected for early maturity, long plant height and large head. Selected lines were used as breeding meterials for F$_1$ hybrid.

• Food Science of Animal Resources
• /
• v.28 no.2
• /
• pp.154-159
• /
• 2008

To investigate the rheological properties of protein mixed gels mediated by microbial transglutaminase (MTGase), pork myofibrillar protein (MFP), sodium caseinate (SC) and their mixture (MS), the various gels were incubated at different temperatures for various times. Extracted MFP, SC and their mixture (MS, 1:1) were incubated at different temperatures ($4^{\circ}C$ vs $37^{\circ}C$) for various times (0, 0.5, 2, 4 hr), and assessed for viscosity, gel strength and other characteristics using differential scanning calorimeter (DSC) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). DSC measurements showed that incubation at $37^{\circ}C$ rather than $4^{\circ}C$ caused marked changes in thermal transition, and MS displayed similar thermal curves (three endothermic transitions) to MFP and SC alone. After incubation at $37^{\circ}C$ for 2 hrs, the viscosity (cP) of MS increased (p<0.05) due to induction by MTGase, whereas no differences were observed at $4^{\circ}C$. However, gel strength values were no different, regardless of incubation temperatures and times. Future research will address how longer incubation times affect the functionality of protein mixed gels mediated by MTGase.

• Applied Chemistry for Engineering
• /
• v.18 no.1
• /
• pp.77-83
• /
• 2007

It is essential that second order nonlinear optical materials have low optical propagation losses in the wavelengths of second harmonic generation for practical applications in waveguides. Three dipolar chromophores substituted with nitro, cyano, and alkyl sulfone as an electron withdrawing group were prepared. The UV-Vis absorption spectra of the cyano and alkylsulfone chromophores showed a blue-shift compared to the nitro chromophore. The introduction of oxadiazole segment in the chromophore structure led to similar spectral shift. The blue-shift can produce low optical loses at second harmonics. The chromophores were successfully attached to a polyimide, yielding side chain polymers. The nonlinear optical property of the prepared optical polymers was determined by measuring electro-optic coefficient at 1.55 mm. The polymers exhibited high glass transition temperature of over $185^{\circ}C$ and thermal stability to $300^{\circ}C$ through differential scanning calorimeter analysis and thermal gravimetric analysis.

• Journal of the Korean Geotechnical Society
• /
• v.27 no.12
• /
• pp.5-15
• /
• 2011

Conventional designs of landfill covers use geosynthetics such as geomembrane and GCL, and clay liners to lower the permeability of final covers of landfill sites. However, differential settlement and the variation of temperature or humidity in landfill sites cause the development of cracks or structural damage inside the final cover. This study examined the application of a Self Recovering Sustainable Liner (SRSL) as an alternative landfill final cover material. SRSL consists of double layers, which have chemicals, can generate precipitates filling the pores of the layers by chemical reaction. The interface material forms an impermeable layer and in case of internal cracks, the reactants of the two layers migrate towards the crack and heal it by forming another liner. In this study the applicability of SRSL material for landfill final cover was examined by performing flexible wall permeameter tests to prove that the hydraulic conductivity is lower than the regulations and unconfined compression tests to judge whether the strength satisfies the restriction for the landfill final cover. Furthermore, the environmental impacts on the permeability and strength were evaluated. The experimental results show that the SRSL has lower hydraulic conductivity and higher strength than the regulations and is little influenced by climatic changes such as wet/dry or freeze/thaw process.

• Korean Journal of Food Science and Technology
• /
• v.26 no.2
• /
• pp.117-122
• /
• 1994

The characteristics of amylose-lipid complex(AL-complex) and cyclodextirn-lipid complex(CL-complex) were investigated by using Differential Scanning Calorimetry(DSC). The enzymatic hydrolysis of amylose which was liberated from AL-complex by the addtion of ${\beta}-cyclodextrin({\beta}-CD)$was also studied. The melting temperatures of AL-complex in corn, wheat, and rice starch were above $100^{\circ}C$ and there were no differences among them. In the presence of lysolecithin, the melting enthalpy and temperature of AL-complex were increased and lysolecithin was very effective in the formation of AL-complex. When ${\beta}-CD$ was added to AL-complex, the endothermic peak of AL-complex at $100^{\circ}C$ decreased and that of CL-complex at $70^{\circ}C$ appeared. These results indicated that the amylose was released from AL-complex by substituting ${\beta}-CD$ for amylose, then by forming CL-complex. As the added amount of ${\beta}-CD$ increased, the peak of AL-complex decreased whereas that of CL-complex increased. Enzymatic hydrolysis rate of AL-complex increased in the presence of ${\beta}-CD$, suggesting that amylose was dissociated from AL-complex and hydrolyzed by amylase.

• Korean Journal of Food Science and Technology
• /
• v.33 no.3
• /
• pp.313-318
• /
• 2001

Physicochemical properties of starch vermicelli (Dangmyun) made with different starches in laboratory were determined to develop a modified corn starch comparable to sweet potato starch which is highly expensive than corn starch but commonly used for starch vermicelli in Korea. Initial temperatures (Ti) of gelatinization of starch vermicelli made in laboratory measured by differential scanning calorimeter, which were above $60^{\circ}C$, were higher than those of starch vermicelli in the market. Their X-ray diffraction peaks were relatively sharp compared with those of starch vermicelli in the market, which showed that starches were not completely gelatinized during the process of starch vermicelli preparation in laboratory. Initial temperature (Ti) of corn starch vermicelli was decreased by $3^{\circ}C$ by hydroxypropylation but increased by $2.5^{\circ}C$ by oxidation. Hardness and compression slope of sweet potato starch vermicelli and mungbean starch vermicelli, which were $11,726{\sim}12,555\;g/cm^2$ and $29,914{\sim}30,604\;g/cm^2$, respectively, were the highest in the samples and those of waxy corn starch were lowest. Hardness and compression slope of starch vermicelli made with corn starch slightly oxidized in the concentration of 0.5% NaOCl at pH 9.0, $40^{\circ}C$ for 30 min. increased and found to be comparable to those of sweet potato starch vermicelli.

• Korean Chemical Engineering Research
• /
• v.43 no.1
• /
• pp.110-117
• /
• 2005

In this work, solid-state inclusion complex powders of itraconazole and $2-hydroxypropyl-{\beta}-cyclodextrin(HP-{\beta}-CD)$ were produced by a supercritical anti-solvent (SAS) process. In order to evaluate the degree of complexation, the thermal behavior of the microparticulate complexes was investigated using differential scanning calorimetry. The experimental results obtained for the solubility and dissolution rate of the microparticulate inclusion complexes in a buffer solution of pH 1.2 showed that the complexation of itraconazole with $HP-{\beta}-CD$ results in a significant increase in the solubility and dissolution rate of itraconazole. The particle size of the SAS-produced inclusion complexes was dramatically reduced ($<0.1-0.5{\mu}m$) compared with untreated itraconazole ($30-50{\mu}m$) and $HP-{\beta}-CD$ ($50-100{\mu}m$). The solubility of itraconazole was increased with the increase of pressure at a constant temperature to ca. $758.6{\mu}g/mL$ in an aqueous medium of pH 1.2. The dissolution rate of itraconazole was observed to be significantly improved and about 90% of itraconazole was found to be dissolved within 5-10 min.