• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.4
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• pp.194-200
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• 2002

The cells of Rhodococcus rhodochrous M33, which produce a nitrile hydratase enzyme, were immobilized in acrylamide-based polymer gels. The optimum pH and temperature for the activity of nitrile hydratase in both the free and Immobilized cells were 7.4 and 45$\^{C}$, respectively, yet the optimum temperature for acrylamide production by the immobilized cells was 20$\^{C}$. The nitrile hydratase of the immobilized cells was more stable with acrylamide than that of the free cells. Under optimal conditions, the final acrylamide concentration reached about 400 g/L with a conversion yield of almost 100% after 8 h of reaction when using 150 g/L of immobilized cells corresponding to a 1.91 g-dry cell weight/L. The enzyme activity of the immobilized cells rapidly de-creased with repeated use. However, the quality of the acrylamide produced by the immobilized cells was much better than that produced by the free cells in terms of color, salt content, turbidity, and foam formation. The quality of the aqueous acrylamide solution obtained was found to be of commercial use without further purification.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.260-266
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• 2006

For the synthesis of polyurethane memory foam stabilizer with fine cells, hydrosilylation reaction with various polyalkyleneoxides and hydrogen functional group of polymethylhydrogensiloxane (D = 75, D' = 15) was conducted. Polyalkyleneoxides (PAO) used in this research were ethylene oxides or ethylene-co-propylene oxides with terminal groups of hydroxides or methyl groups. To analyze the molecular structures and molecular weights as well as the reaction yields (98%), NMR and GPC analysis were executed. Synthesized siloxane surfactants modified with polyalkylene (EO = 12 units) were applied to producing flexible polyurethane fine memory foams from 0.6 pphp to 2.0 pphp. By controlling the amount of the surfactant, physical characteristics, the polyurethane memory foam with cell size (minimum $0.868{\mu}m$), air flows (-78 KPa), and recovery times (8 sec) were achieved.

• Applied Microscopy
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• v.25 no.1
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• pp.86-95
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• 1995

This study was accomplished to investigate the ultrastructure of mucous glands in dorsal skin of frog (Rana catesbeiana) by means of scanning and transmission electron microscopes. The dorsal skin of Rana catesbeiana is composed of epidermis and dermis. The cutaneous mucous glands consist of inner glandular epithelial cells and outer myoepithelial cells. Glandular epithelial cells are divided into four types by the microscopic ultrastructure; ER-rich cell, round secretory granule-containing cell, foam-like granule mass-containing cell, mitochondria-rich cell. Myoepithelial cell has a long elliptical nucleus and filled with fibrous materials in the cytoplasm. As a result of scanning microscopic observation, the surface of dorsal skin is covered with cutaneous protrusions. The opening sites of the mucous glands are irregularly distributed in dorsal skin.

• Korean Journal of Veterinary Service
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• v.23 no.4
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• pp.309-312
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• 2000

Pathological findings of natural cases of rabbit hemorrhagic disease was investigated. Clinically inappentence, increase in body temperature, depression, bloody foam from nostrils, and sudden death were recognized. Characteristic anatomical findings were hemorrhages in the lungs, liver, kidneys, and heart. Intestinal catarrh and retention of turbid urine in urinary bladder were also often observed. Severe .necrosis of hepatic cells, massive hemorrhages in many organs and membranous glomerulonephritis with hyaline droplet formation were characteristic changes under the microscopy. Perivascular cuffing of brain and catarrhal enteritis were also seen in many cases.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2003.11a
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• pp.37-43
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• 2003

Engorgement of macrophages with cholesterol is the defining pathological characteristic of atherosclerotic plaques, the cause of most heart attacks and strokes. Activated human macrophages uptake low density lipoprotein (LDL) by the bulk-phase fluid, and aggregated LDL by patocytosis. After incorporation of LDL and aggregated LDL into macrophages, neutral cholesterol esterase is decreased and cholesterol efflux is also deceased, resulting that macrophages become foam cells.

• Journal of Life Science
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• v.32 no.2
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• pp.142-147
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• 2022

Oxysterols are known to be involved in the physiopathology of atherosclerosis. Since 7-ketocholesterol (7-KC) is found in large amounts in oxysterols and in atherosclerotic plaque, the study on how 7-KC may affect monocyte differentiation induced by phorbol myristate acetate (PMA) in the monocytic cell line, THP-1, is essential. 7-KC induced a dose-dependent reduction in cell proliferation without inducing cytotoxicity, and the substantial staining of Nile red demonstrates the increased absorption of intracellular lipids. Although 7-KC itself did not increase cell adhesion, it markedly decreased the adhesion of cells treated with PMA. Furthermore, by observing the effect of 7-KC on phagocytosis using fluorescent-labeled latex beads, 7-KC's ability to abolish phagocytosis in PMA-stimulated macrophages was illustrated. The effect of 7-KC on the expression of selected protein markers on the process of differentiation induced by PMA in THP-1 cells was also examined. 7-KC inhibited expression of ICAM-1, CD11a, SR-A1, and SR-B2 (CD36) in PMA-stimulated THP-1 cells. Conversely, 7-KC drastically increased the expression of SR-D1 (CD68)in PMA-stimulated THP-1 cells. In conclusion, these results suggest that 7-KC modulates monocyte differentiation and activation via the intracellular accumulation of lipid droplets.

• KSBB Journal
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• v.16 no.1
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• pp.24-29
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• 2001

Recently hepatocyte-based bioartificial liver (BAL) and hepatocyte transplantation have been actively investigated to treat acute hepatic failure. The BAL acts as a bridge to provide patients with more time until a donor organ becomes available for transplantation or until their own liver can be regenerated. In this study, we manufactured a polyurethane foam (PUF) using 15% NCO-prepolymer with a pore opening that allows it to be used as a hepatocyte immobilizing material. Cubes of PUF (3 mm dim.) were seeded with rat primary hepatocytes at a density of 5.5$\pm$1.1$\times$ $10^6$ cells/$cm^3$ PUF by centrifuging them together. The cell laden PUF cubes were packed into a prototype reactor and perfused with a hormonally defined medium for a week. Hepatocytes in the pores of the PUF formed spheroids that showed stable ammonia removal and urea synthesis activities. The albumin production level was comparable to other BAL systems. The PUF packed hepatocyte bioreactor has the potential to be used as a BAL.

• Polymer(Korea)
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• v.34 no.1
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• pp.8-13
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• 2010

The physical properties of polymeric foams depend on the density of foams, physical properties of base polymers, the content of open cells, and cell structures including the size and its distribution, the shape of cell, and the thickness of skin layer. The foam density is affected by the chemistry of raw materials, the concentration of crosslinking agent and the blowing agent as well as the operating parameters during production process. In this study, the basic formulations of foams are composed of polyester polyol, MDI, amine catalyst, tin catalyst, silicone surfactant, and water. Cross-linking density of polyurethane was increased by using chain extenders. Also, the mechanical properties of polyurethane foam were improved by using the inorganic fillers (silica 1,2 and talc 1,2) having different $SiO_2$ contents and particle sizes. We investigated the properties of modulus, tensile strength, compressive strength and hardness of foams obtained by changing kind of inorganic filler and chain extender, and observed the distribution of inorganic filler as well as variation of cell size within the foams by electron microscopy.

• KSBB Journal
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• v.11 no.1
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• pp.46-51
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• 1996

Cell separation by means of continuous foam separation of Saccharomyes formosensis without additive was investigated. The yeast separation ratio was improved at low feed rates, high nitrogen rates, optimum pH and temperature for ethanol production, dilution of cultivation medium and addition of 0.5g/$\ell$ $CaCl_2$. Percentage of yeast removal and yeast separation ratio were more than 85 when continuous foam separation was operated in optimum condition..

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.2
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• pp.109-115
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• 2017

Using the computational fluid dynamics (CFD) technique, we performed a numerical simulation in anodesupported solid oxide fuel cell (SOFC). The effect of gas channel/rib width on the cell performance and temperature uniformity was investigated in planar type SOFC. The open source CFD toolbox, OpenFOAM, was used as a numerical analysis tool. As a result, the effect of gas channel/rib width on the cell performance and temperature uniformity was not significant if the oxygen depletion is not occurring. On the other hand, the usage of a wide rib and operation at high current density may lead to performance degradation due to oxygen depletion.