• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.2
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• pp.252-263
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• 1997

Steady-state two-dimensional natural convective heat transfer in horizontal cylindrical annuli was studied by solving the governing equations based on the primitive variables. Emphasis was put on the occurrence of the multiple solutions at a given set of parameter values, and on the determination of the bifurcation points at which those multiple solutions begin to branch out. The multicellular flow pattern from the results of melting process in an isothermally heated horizontal cylinder for high Rayleigh numbers, was used as initial guesses for the field variables. This was succeeded in new bifurcation point to tetracellular solutions for an identical set of parameter variables of previous works. The close examination of flow pattern transition around bifurcation point was also conducted. It was found that the mechanisms of flow transition are different depending on the critical Rayleigh number of bifurcation point.

• Journal of computational fluids engineering
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• v.18 no.2
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• pp.35-40
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• 2013

Natural convection of air with Pr=0.7 between two horizontal plates with small magnitude non-uniform temperature distribution[${\in}{\Delta}Tsin({\kappa}X/H)$, H : gap width, X : horizontal coordinate] in the lower plate is numerically(${\in}=0.01$) investigated. In the conduction-dominated regime with $Ra{\leq}1700$, two upright cells are formed over one wave length($2{\pi}/{\kappa}$). For small wave number, the flow becomes unstable with increase of Rayleigh number, and multicellular convection occurs above a critical Rayleigh number. The flow patterns are classified by the number of eddies over one wave length. When ${\kappa}=1$, a transition of $2{\rightarrow}4{\rightarrow}6$ eddy flow occurs with increase of Rayleigh number, and no hysteresis phenomenon is observed. Dual and triple solutions are found for ${\kappa}=1$, and transitions of $10{\rightarrow}8$, $8{\rightarrow}6$, $6{\rightarrow}4{\rightarrow}2$ eddy flow occur with decrease of Rayleigh number.

• Journal of Life Science
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• v.10 no.1
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• pp.22-36
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• 2000

The mammary gland contains a subpopulation of epithelial cells with large proliferative potentials which are the likely targets for carcinogens. These clonogenic cells can proliferate and differentiate into functional glandular structures. Multicellular secretory alveolar units (AU) develop from these clonogens in grafts of monodispersed rat mammary epithelial cells (RMEC) in gland-free mammary fat pads in intact recipient F344 rats co-grafted with mammotropic hormone-secreting pituitary tumors (MtT F4). Multicellular nonsecretory ductal units (DU) develop in grafts of monodispersed RMEC in gland-free fat pads in adrenalectomized recipient WF rats co-grafted with MtT W10. However, this effect were reversed by hydrocortisone replacement therapy. RMEC were isolated from appropriate donor rats as monodispersed mixed cells or, alternatively, RNA＋ cells were sorted by flow cytometry of mixed RMEC stained with FITC-RNA and PE-anti-Thy-1.1 monoclonal antibody. We grafted mixed or sorted PNA+ cells in gland-free mammary fat pads in recipient rats that were endocrinologically manipulated to induce AU or DU. Cells were also isolated from these AU or DU as mixed or sorted RNA＋ cells and sub-transplanted in recipient rats treated appropriately to induce AU or DU, respectively. Cells obtained from AU in grafts gave rise to clonal AU and from DU in grafts to DU on sub-transplantation in appropriate recipients. When adrenalectomized recipient WF rats co-grafted with MtT W10 received daily subcutaneous injections of hydrocortisone for periods of 21 days following the PHA＋ cell transplantation, AU, instead of DU, were developed. The histologies of these secondary AU and DU were not different from those of the primary AU and DU. Casein and laminin proteins were demonstrated by immunocytochemical staining of primary and secondary AU. Electron micrographs also demonstrated that AU were composed of secretory cells with milk protein in the cytoplasm. DU were composed of little or non-secretory ductal epithelial cells. These AU and DU also secreted large amounts of lipids. Clonogenic cells were more common in DU than in AU. Thus, AU and DU contain persistent subpopulations of clonogenic stem-like cells.

• Journal of computational fluids engineering
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• v.21 no.4
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• pp.11-18
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• 2016

A numerical study is conducted on the optical fiber coating flow in a primary coating nozzle consisting of three major parts: a resin chamber, a contraction and a coating die of small diameter. The flow is driven by the optical fiber penetrating the center of the nozzle at a high speed. The axisymmetric two-dimensional flow and heat transfer induced by viscous heating are examined based on the laminar flow assumption. Numerical experiments are performed with varying the convergent angle of nozzle contraction and the optical fiber drawing speed. The numerical results show that for high drawing speed greater than 30 m/s, there is a transition in the essential flow features depending on the convergent angle. For a large convergent angle greater than $30^{\circ}$, unfavorable multicellular flow structures are monitored, which could be associated with wall boundary-layer separation. In the regime of small convergent angle, as the angle increases, the highest resin temperature at the exit of die and the coating thickness decrease but the sensitivity of coating thickness on drawing speed and the maximum shear strain of resin on the optical fiber increase. The effects of the convergent angle are discussed in view of compromise searching for an appropriate angle for high-speed optical fiber coating.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8445-8450
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• 2016

Background: Breast cancer is the most common neoplasm in women and the most frequent cause of death in those between 35 and 55 years of age. All multicellular organisms have an innate immune system, whereas the adaptive or 'acquired' immune system is restricted to vertebrates. This study focused on the effect of conditioned medium isolated from cultured breast cancer cells on NB4 neutrophil-like cells. Materials and Methods: In the current study neutrophil-like NB4 cells were incubated with MCF-7 cell-conditioned medium. After 6 h incubation the intracellular receptor TLR2, was analyzed. Results: The results revealed that MCF-7 cell-conditioned medium elicited expression of TLR2 in NB4 cells. Conclusions: This treatment would result in the production of particular stimulants (i.e. soluble cytokines), eliciting the expression of immune system receptors. Furthermore, the flow cytometry results demonstrated that MCF-7 cell-conditioned medium elicited an effect on TLR2 intracellular receptors.

• Journal of applied mathematics & informatics
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• v.12 no.1_2
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• pp.281-289
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• 2003

The convection of water is investigated in the vicinity of its density maximum temperature (277 K) in an inclined square cavity in the presence of heat sources. Numerical investigations are carried out by maintaining one of the vertical walls uniformly at 273 K and varying the other wall between temperatures 275 K and 285 K at different inclinations angles. The isotherms, streamlines and velocity profiles reveal the possible existence of multicellular fluid motions, and bidirectional velocity distributions. These fluid flow and heat transfer characteristics are significantly modified by the cavity inclination in the presence of heat sources.

• Journal of Life Science
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• v.10 no.1
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• pp.37-44
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• 2000

The mammary gland contains a subpopulation of epithelial cells with large proliferative potentials which are the likely targets for carcinogens. These clonogenic cells can proliferate and differentiate into functional glandular structures. Rat mammary epithelial cells (RMEC) were isolated and characterized in vitro. By flow cytometry of RMEC stained with fluorescein isothiocyanate-peanut agglutinin(PNA) and phycoerythrin anti-Thy-1.1 monoclonal antibody, it was possible to four cell subpopulations from 7-8 week old F344 female rat mammary glands: cells negative to both reagents (B-), PNA-positive cells (PNA+), Thy-1.1-positive cells (Thy-1.1+), and cells positive to both reagents (B+). When single PNA+ cells were isolated and cultured in Matrigel with irradiated (∼50 Gray) 3T3 fibroblast feeder layer, they gave rise to multicellular clonal structures of three types: alveolar, foamy alveolar, and squamous colonies. The developed structures were similar to the mammary glands in vivo. These results suggest that some of PNA+ cells possesses many of the characteristics of multipotent clonogenic stem-like cells.

• 대한공업교육학회지
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• v.33 no.2
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• pp.300-311
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• 2008

This study investigates the natural convection of air(Pr=0.7) between two walls having a small- wave- number sinusoidal temperature distributions with a phase difference. The wave number and the phase difference of wall temperatures are k=0.5 and ㄱ/2, respectively. In the conduction-dominated regime at small Rayleigh number, two slightly inclined cells are formed over one wave length. At higher Rayleigh number, however, multicellular convection occurs in thermally unstable region. A spatial symmetry is intermittently broken in the transient period at the Rayleigh number near the critical value. The steady-state flows always satisfy the spatial symmetry. A steep increase of Nusselt number occurs near the Rayleigh number at which transition of flow pattern occurs.

• Journal of Pharmaceutical Investigation
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• v.36 no.4
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• pp.231-237
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• 2006

Hypoxia in solid tumors is known to contribute to intrinsic chemoresistance. Histocultures are in vitro 3 dimensional cultures of tumor tissues and maintain the characteristic microenvironment of human solid tumors in vivo including hypoxia and multicellular structure. In this study, we evaluated the pharmacodynamics of tirapazamine(TPZ), a hypoxia-selective cytotoxin, in human non small cell lung cancer(NSCLC) cells grown as monolayers and histocultures. Antiproliferative activity of TPZ was determined after various conditions of drug exposure, and cell cycle arrest and apoptosis were also measured using flow cytometry. In monolayers, hypoxia selectivity measured by hypoxic/normoxic cytotoxicity ratio was increased with longer exposure. Lower cytotoxicity of TPZ was observed in histocultures compared to monolayers, however, a similar level of cytotoxicity was obtained with longer exposure of 96 hr. TPZ induced $G_2/M$ arrest and apoptosis in both culture conditions, which were greatly enhanced under hypoxic condition. Our data clearly showed the different pharmacodynamics of TPZ in monolayers and histocultures. Antiproliferative activity of TPZ against human solid tumors can be improved with longer drug exposure by exploiting drug delivery systems or by combining angiogenesis inhibitors to maintain drug concentration in tumor tissues.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.11
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• pp.999-1005
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• 2004

Thermal convection between two horizontal walls kept at small amplitude nonuniform temperatures of the form, $T_L=T_1+a{\Delta}T$ sin kx and $T_U=T_2+b{\Delta}T\;sin(kx-{\beta})$ with a, $b{\ll}1$, is numerically investigated. When the Rayleigh number is small, an upright cell is formed between two walls at ${\beta}=0$; the cell is tilted at ${\beta}={\pi}/2$, and a flow with two-tier-structure cells occurs at ${\beta}={\pi}$. As the Rayleigh number is increased, Nusselt number increases smoothly for ${\beta}=0\;and\;{\pi}/2$, but increases rather steeply for ${\beta}={\pi}$ near the critical Rayleigh number ($Ra_c=1708$). When the wave number is small (k=0.5), multicellular convection occurs over one wave length, for all phase differences, and multiple solutions are found.