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김경수,이우걸,윤용수,정일현 한국공업화학회 2003 응용화학 Vol.7 No.2
Fe-C:H films were deposited in a RF plasma with ferrocene (Fe)C_(5)H_(5))₂). The deposited Fe-C:H films consisted of C-H_(n), C=C, and C-CH_(n). The deposition rate linearly increased with the flow rate of hydrogen. In all conditions of experiments, the band gap pf Fe-C:H film was about 3.8 eV.
Effect of surface morphology of calcium phosphate on osteoblast-like HOS cell responses
Woo-Kul Lee,Sang-Mi Lee,김현만 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.5
Calcium phosphate (CaP) films with different surface roughness are synthesized on a polystyrene surface as a possible candidate for improving the biocompatibility of solid surfaces. These CaP films are used to investigate the influences of the surface roughness and chemical composition on the HOS osteoblast-like cells adhesion, spreading, proliferation, and differentiation. A polystyrene culture plate is used as the control surface. The CaP substrates are designated as a smooth, moderate, and rough surface according to the surface roughness. For smooth and moderate surfaces, a relatively small difference in the surface roughness is observed but the difference in their chemical composition is more significant than the others. Cell adhesion, spreading, proliferation, and differentiation appear to be dependent on surface roughness. These cellular responses are more active on the smoother surfaces than on the rough surface but are more pronounced on the moderate surface. The cell responses are reduced when HOS cells are cultured on the rough surface. The number of cells released from the control surface by trypsinization is greater than the CaP surfaces after a short period of incubation (5 h). However the cells released from smooth and moderate CaP surfaces are equivalent to or greater than the control at the longer period of incubation (17 h). Spreading and proliferation are greater on the CaP surfaces than on the control. The alkaline phosphatase-specific activity is very low during 1 and 2 weeks of culturing but dramatically increases after 3 weeks on all surfaces. The enzyme activity on the control is greater than on the CaP surfaces. The moderate surface shows the greatest enzyme activity in all cases among the CaP surfaces. Although a direct relation between surface chemistry and cell responses has not been established, the surface composition may play a cooperative role in characterizing the cellular responses. According to these results, the moderate surface is the most favorable substrate in terms of surface roughness and chemical composition for cell adhesion, spreading, proliferation and differentiation among all the CaP surfaces.
Interfacial Tension Kinetics of Nisin and β-Casein at on Oil - Water Interface
Lee, Woo Kul,Ahmad, Bani Jaber,McGuire, Joseph,Daeschel, Mark A .,Jung, Il Hyun 한국화학공학회 2000 Korean Journal of Chemical Engineering Vol.17 No.2
The concentration- and time-dependence of interfacial pressure of raisin and β-casein at an n-hexadecane-water interface were evaluated by using DuNou¨y tensiometry. The two emulsifiers attained interfacial saturation at a bulk concentration of about 0.1 mg/ml, the reduction of the interfacial tension by nisin at that concentration being about equivalent to that of β-casein. The time dependence of interfacial tension recorded for each protein was described by using two kinetic models. In the first, the reduction of interfacial tension with time was considered to be a result of molecular penetration into the interface followed by rearrangement. Nisin exhibited more rapid penetration and rearrangement at the interface than did β-casein. In the second, the model allowed for the parallel, irreversible adsorption of protein into each of two states from solution, where state 2 molecules occupy a greater interfacial area and are more tightly bound than state 1 molecules. The extent of adsorption in state 1 and state 2 was determined to be highly concentration dependent for each protein; adsorption occurs mostly in state 1 at high concentration and mostly in state 2 at low concentrations.
Kinetic Model for the Simulation of Hen Egg White Lysozyme Adsorption at Solid/Water Interface
Lee, Woo-Kul,Ko, Jea Seung 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.3
A simulation model for adsorption kinetics of hen egg shite lysozyme (HFW) adsorption to hydrophilic silica is proposed. The adsorption kinetic data were monitored by using in-situ ellipsometry. The model is based on an irreversible adsorption mechanism allowing two different adsorbed states. The adsorbed states were differentiated based on binding strengths resistant to the concentration gradient exerted by rinse. Molecules desorbing and remaining upon rinse were identified as loosely bound (state 1) and tightly bound (state 2) states, respectively. The adsorption rate constants were assumed to be a time-dependent nonlinear function in order to account for the change in surface properties originating from the protein layer formed on the surface. The parameters of adsorption rate constants were evaluated by using adsorption kinetic data at different protein concentrations, and the relationships between the adsorption parameters and protein concentration were established which eventually demonstrated a linear relationship. The established relations between the adsorption parameters and concentration elucidated the effect of protein concentration on adsorption to hydrophilic silica.
The Effect of Interparticle Forces on Fluidization Regimes in the Magnetized Fluidized Beds
Lee, Woo Kul,Jovanovic, Goran,Kim, Hee Taik 한국화학공학회 1999 Korean Journal of Chemical Engineering Vol.16 No.3
This paper investigated the influence of interparticle forces on the quality of fluidization in a magnetically stabilized fluidized bed (MSFB), where we can $quot;artificially$quot; create interparticle forces (F_(attr)) of any magnitude by applying an external magnetic field to ferromagnetic particles. A theoretical model was proposed which predicts the transition point from a homogeneous to a heterogeneous fluidization as a function of the magnitude of the interparticle force and other physical characteristics of both particles and fluids that are usually observed in fluidization (p_p, p_f,μ,d_p,ε). The concept of the elastic wave velocity, U_e, and the continuity wave velocity, Uε , was introduced. In particular, the interparticle force manipulated by an externally applied magnetic field was taken into account in addition to a general consideration of a conventional fluidized bed. Bubbles form in a bed when the continuity wave velocity becomes faster than the elastic wave velocity. The simulation demonstrated the proposed model could predict the transition point of fluidization regime with reasonable accuracy.