• KSBB Journal
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• v.24 no.6
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• pp.563-569
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• 2009

Fibroin is an insoluble structural protein from Bombyx mori. It can be solubilized by dissolving in a hot $CaCl_2$ solution and subsequent dialysis. The aqueous solution is unstable and a transition from aqueous fibroin molecules rich in random coil is undergo to one rich in $\beta$-sheet content, resulting in hydrogelation. However, fibroin gel is so fragile and plastic that its mechanical property should be reformed for various applications. In this report, a semi-solid form of fibroin gel was prepared using glycerol and ethanol and was investigated to analyze their flow properties. A fibroin gel with 80% glycerol showed pseudoplastic and thixotropic properties. The square root of its yield stress varied linearly with fibroin concentration and it extrapolated to zero shear stress at 0.2% fibroin. A fibroin gel with 40% ethanol was shown to be highly thixotropic but its shear-thinning behavior was only observed above a certain level of shear rate. Its pseudoplasticity was restored by a high rate of shear stress.

• Preventive Nutrition and Food Science
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• v.8 no.3
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• pp.278-283
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• 2003

Textural properties of tofu manufactured with micronized full-fat soyflour (MFS) were enhanced by the addition of soy protein isolate, whey protein concentrate, chitosan oligosaccharide and mushroom powder. The MFS solution (14.2% solid content) was converted to semi-solid tofu by a two-stage heat treatment with the addition of 4% coagulant mix. The MFS tofu was evaluated by a compression test as well as sensory evaluation. To produce the semi-solid gel (MFS tofu) with reasonably high strength and toughness, the MFS solution with 14.2% solid content and 7.0% protein had to be heat treated at 121$^{\circ}C$ for 3min. The relative toughness of MFS tofu was increased by the addition of SPI, showing a 144% increase. The toughness of MFS tofu prepared with the MFS/SPI mixture was greatly increased by the addition of WPC at the level of 0.7% and the water separation from MFS tofu was greatly reduced. Furthermore, the toughness and strength of MFS/SPI tofu was enhanced by the addition of 0.1% chitosan oligosaccharide and 0.2% mushroom powder. The sensory evaluation of the tofu fortified with SPI, chitosan oligosaccharide and mushroom powder was superior to that of MFS tofu, with a higher score for overall preference.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.39 no.1
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• pp.47-54
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• 2013

Aloe gel microcapsule was prepared by dehydrating dispersed aloe gel droplets in the form of W/O emulsion using a vacuum evaporator. The microcapsules remained in stable suspensions after washing with mineral oil and had a homogeneous spherical structure with diameter less than 6.4 ${\mu}m$. The microcapsule suspension in mineral oil (> 41%) exhibited a step increase in viscosity and shear-thinning but not showed thixotropic behavior with a yield stress higher than 300 Pa. The dense suspension appeared to be semi-solid as the microcapsule fraction increases and to be stable after heat treatment at $105^{\circ}C$ for 15 min. In conclusion, the dense suspension composed of gel microcapsules is expected to provide a basic cosmetic formulation that can be applied to develop various types of aloe gel cosmetic products.

• Journal of Microbiology and Biotechnology
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• v.25 no.4
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• pp.423-430
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• 2015

Aerobic CH₄ oxidation is an important CH₄ sink in landfills. To investigate the distribution and community diversity of methanotrophs and link with soil characteristics and operational parameters (e.g., concentrations of O₂, CH₄), cover soil samples were collected at different locations and depths from the Mengzi semi-aerobic landfill (SAL) in Yunnan Province of southern China. Specific PCR followed by denaturing gradient gel electrophoresis and realtime PCR were used to examine methanotrophs in the landfill cover soils. The results showed that different locations did harbor distinct methanotroph communities. Methanotrophs were more abundant in areas near the venting pipes because of the higher O₂ concentrations. The depth of 20-25 cm, where the ratio of the CH₄ to O₂ was within the range from 1.3 to 8.6, was more conducive to the growth of CH₄-oxidizing bacteria. Type II methanotrophs dominated in all samples compared with Type I methanotrophs, as evidenced by the high ratio of Type II to Type I methanotrophic copy numbers (from 1.76 to 11.60). The total copy numbers of methanotrophs detected were similar to other ecosystems, although the CH₄ concentration was much higher in SAL cover soil. Methylobacter and Methylocystis were the most abundant Type I and Type II methanotrophs genera, respectively, in the Mengzi SAL. The results suggested that SALs could provide a special environment with both high concentrations of CH₄ and O₂ for methanotrophs, especially around the vertical venting pipes.

• Biomedical Science Letters
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• v.19 no.1
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• pp.41-47
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• 2013

Pluripotent stem cells (PSCs) have lots of potential in biomedical sciences owing to its potential to differentiate into any kind of cells in the body. However, it is still a challenge to culture PSCs on a large scale for application to regenerative medicine. Herein, we introduce a synthetic polymer that enables large-scale suspension culture of human PSCs. By employing suspension culture, it became unnecessary to use conventional substrata such as mouse embryonic fibroblast (MEF) or Matrigel$^{TM}$, which are believed to be main causative sources of xenogeneic contamination in cultured human PSCs in vitro. Human PSCs were cultured in the medium in which elastin-like polypeptide (ELP) dissolved. The ELP in the medium became harden as temperature increases by transforming the medium into a semi-solid gel that supported growth of human PSCs in suspension. Gel-sol transition temperature of ELP can be adjusted by modifying the peptide sequence in which 5 amino acids, Val-Pro-Gly-Xaa-Gly, repeated sequentially. We constructed 3D suspension media having transition temperature around $33{\sim}35^{\circ}C$ using an ELP consisted of 40, 60, or 80 repeats of a monomer, which was Val-Pro-Gly-Val-Gly. Among the ELPs, ELP80 was chosen as the best ELP to support growth of human PSCs in suspension culture. This result suggests that the ELP80 can be a medium component for culturing human PSCs in large-scale.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.6
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• pp.387-393
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• 2007

We examined the conditions for separating and preserving the male and female gametophytes of Kjellmaniella crassifolia. The highest percentage of zygote germination (85%) was on semi-solid medium composed of 1.0% transfer gel agar at $15\;^{\circ}C$ and $20\;{\mu}mol/m^2/s$ after a 4-week culture. Zygote germination in PESI liquid medium was 93.5% at $20\;^{\circ}C$ and $20\;{\mu}mol/m^2/s$. The maximum zygote growth was $252{\pm}19.7\;{\mu}m$ on 1.0% transfer gel agar at $15\;^{\circ}C$ and $40\;{\mu}mol/m^2/s$ after 5-week culture, and was $76.7{\pm}2.8\;{\mu}m$ in PESI liquid medium at $20\;^{\circ}C$ and $40\;{\mu}mol/m^2/s$. The respective numbers of separated male and female gametophytes from germinated zygotes were 157 and 93 on 1.0% transfer gel agar and 14 and 28 in PESI liquid medium. The maximum growth of separated male and female gametophytes was $575{\pm}28.3\;{\mu}m$ at $5\;^{\circ}C$ and $60\;{\mu}mol/m^2/s$ and $686{\pm}35.4\;{\mu}m$ at $20\;^{\circ}C$ and $20\;{\mu}mol/m^2/s$ in PESI liquid medium after 3 weeks, respectively. The highest percentage fertilized was $93.3{\pm}5.8%$ at $15\;^{\circ}C$ and $20\;{\mu}mol/m^2/s$ in PESI liquid medium. These results show that the best conditions for the separation and preservation of gametophytes (male and female) consisted of culturing on 1.0% transfer gel agar at $15\;^{\circ}C$ and $20\;{\mu}mol/m^2/s$.