• Applied Chemistry for Engineering
• /
• v.25 no.6
• /
• pp.632-638
• /
• 2014

Batch adsorption studies including equilibrium, kinetics and thermodynamic parameters for the adsorption of new fuchsin dye using granular activated carbon were investigated with varying the operating variables such as initial concentration, contact time and temperature. Equilibrium adsorption data were fitted into Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherms. Adsorption equilibrium was mostly well described by Langmuir Isotherm. From the estimated separation factor of Langmuir ($R_L$ = 0.023), and Freundlich (1/n = 0.198), this process could be employed as an effective treatment for the adsorption of new fuchsin dye. Also based on the adsorption energy (E = 0.002 kJ/mol) from Dubinin-Radushkevich isotherm and the adsorption heat constant (B = 1.920 J/mol) from Temkin isotherm, this adsorption is physical adsorption. From kinetic experiments, the adsorption reaction processes were confirmed following the pseudo second order model with good correlation. The intraparticle diffusion was a rate controlling step. Thermodynamic parameters including changes of free energy, enthalpy, and entropy were also calculated to predict the nature of adsorption. The change of enthalpy (92.49 kJ/mol) and activation energy (11.79 kJ/mol) indicated the endothermic nature of adsorption processes. The change of entropy (313.7 J/mol K) showed an increasing disorder in the adsorption process. The change of free energy found that the spontaneity of process increased with increasing the adsorption temperature.

• Journal of Biomedical Engineering Research
• /
• v.25 no.5
• /
• pp.361-367
• /
• 2004

The axial compressive strength, relative 3-D stability and osteoconductive shape design of an intervertebral fusion cage are important biomechanical factors for successful intervertebral fusion. Changes in the stress distribution of the vertebral end plate and in cage stability due to changes in the spike shape of a newly contrived box-shaped fusion cage are investigated. In this investigation, the initial contact of the cage's spikes with the end plate and the penetration of the cage's spikes into the end plate are considered. The finite element analysis is conducted to study the effects of the cage's spike height, tip width and angle on the stress distribution of the vertebral end plate, and the micromigration of the cage in the A-P direction. The stress distribution in the end plate is examined when a normal load of 1700N is applied to the vertebra after inserting 2 cages. The micromigration of the cage is examined when a pull out load of l00N is applied in the A-P direction. The analysis results reveal that the spike tip width significantly influences the stress concentration in the end plate, but the spike height and angle do not significantly influence the stress distribution in the end plate touching the cage's spikes. In addition, the analysis results show that the micromigration of the cage can be reduced by adjusting the spike angle and spike arrangement in the A-P direction. This study proposes the optimal shape of an intervertebral fusion cage, which promotes bone fusion, reduces the stress concentration in a vertebral end plate, and increases mechanical stability.

• Applied Chemistry for Engineering
• /
• v.25 no.4
• /
• pp.430-436
• /
• 2014

Allura Red (AR) is a water-soluble harmful tar-based food colorant (FD & C Red 40). Batch adsorption studies were performed for the removal of AR using bituminous coal based granular activated carbon as adsorbent by varying the operation parameters such as adsorbent dosage, initial concentration, contact time and temperature. Experimental equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin isotherms. The equilibrium process was described well by Freundlich isotherm. From determined separation factor ($R_L$), adsorption of AR by granular activated carbon could be employed as effective treatment method. Temkin parameter, B was determined to 1.62~3.288 J/mol indicating a physical adsorption process. By estimation of adsorption rate experimental data, the value of intraparticle diffusion rate constant ($k_m$) increased with the increasing adsorption temperature. The adsorption process were found to confirm to the pseudo second order model with good correlation. Thermodynamic parameters like change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298~318 K. The negative Gibbs free energy change (${\Delta}G$ = -2.16~-6.55 kJ/mol) and the positive enthalpy change (${\Delta}H$ = + 23.29 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption process, respectively.

• The Journal of Korean Academy of Prosthodontics
• /
• v.44 no.3
• /
• pp.284-294
• /
• 2006

Statement of problem. Proliferation of Candida albicans is primarily within the plaque on the fitting surface of the denture rather than on the inflamed mucosa. Consequently, the treatment of the denture is equally important as treatment of the tissue. Cleansing and disinfection should be efficiently carried-out as the organisms can penetrate into the voids of the acrylic resin and grow in them, from which they can continue to infect and reinfect bearing tissues. Purpose. The purpose of this study was to evaluate the applicability of photocatalytic reaction to eliminate Candida albicans from acrylic resin denture base, and to investigate the anti-fungal effect with various UVA illumination time. Materials and Methods. The specimens were cured by the conventional method following the manufacturer's instruction using thermal polymerized denture base resin (Vertex RS: Dentimex, Netherlands). $TiO_2$ photocatalyst sol(LT), which is able to be coated at normal temperature, was made from the Ti-alkoxide progenitor. The XRD patterns, TEM images and nitrogen absorption ability of the $TiO_2$ photocatalyst sol(LT) were compared with the commercial $TiO_2$ photocatalyst P-25. The experimental specimens were coated with the mixture of the $TiO_2$ photocatalyst sol(LT) and binder material (silane) using dip-coater, and uncoated resin plates were used as the control group. Crystallinity of $TiO_2$ of the specimen was tested by the XRD. Size, shape and chemical compositions were also analyzed using the FE-SEM/ EDS. The angle and methylene blue degradation efsciency were measured for evaluating the photocatalytic activity of the $TiO_2$ film. Finally, the antifungal activity of the specimen was tested. Candida albicans KCTC 7629(1 ml, initial concentration $10^5$ cells/ ml) were applied to the experiment and control group specimens and subsequently two UVA light source with 10W, 353 nm peak emission were illuminated to the specimens from 15cm above. The extracted $2{\mu}l$ of sample was plated on nutrient agar plate ($Bacto^{TM}$ Brain Heart Infusion; BD, USA) with 10 minute intervals for 120 minute, respectively. It was incubated for 24 hours at $37^{\circ}C$ and the colony forming units (CFUs) were then counted. Results. Compared the characteristics of LT photocatalyst with commercial P-25 photocatalyst, LT were shown higher activity than P-25. The LT coated experimental specimen surface had anatase crystal form, less than 20 nm of particle size and wide specific surface area. To evaluate the photocatalytic activity of specimens, methylene blue degradation reaction were used and about 5% of degradation rate were measured after 2 hours. The average contact angle was less than $20^{\circ}$ indicating that the LT photocatalyst had hydrophilicity. In the antifungal activity test for Candida albicans, 0% survival rate were measured within 30 minute after irradiation of UVA light. Conclusion. From the results reported above, it is concluded that the UVA-LT photocatalytic reaction have an antifungal effect on the denture surface Candida albicans, and so that could be applicable to the clinical use as a cleaning method.

• Journal of Periodontal and Implant Science
• /
• v.36 no.3
• /
• pp.673-682
• /
• 2006

Recent study shows that implant design has a great impact on initial stability in bone. The ITI $TE^{(R)}$ implant, designed originally for immediate placement has a tapered/ cylindrical form which fits the anatomical shape of the natural alvelous or tooth root. The increased diameter at the collar region coupled with more threads lead to more bone contact and enhanced stability. The aim of this retrospective study is to evaluate the clinical use and the efficacy of recently introduced ITI TE implant with a new macro-design. The following results are compiled from 139 patients who received ITl TE implant surgery at the periodontal department. of Yonsei University Hospital between July 2002 and September 2005. 1. 139 patients received 173 ITl $TE^{(R)}$ implants in their maxilla and mandible (Mx 82, Mn 91). Posterior area accounted for 84% of the whole implant surgery, 2. In the distribution of bone quality, type III(41,0%) was the most, followed by type IV(41,0%) and type II (27.7%). As for the bone quantity, type B(43.9%) was the most, followed by type C(42.2%), type D(12.2%) and type A(1.7%). 3. 125 implants(83.9%) were treated by single crown, which accounted for the majority. 4, The total implant survival rate was 100% after a mean follow-up period of 21.2 months. This preliminary data with ITl $TE^{(R)}$ implant showed excellent survival rate although the majority of implants evaluated in this study were placed in the posterior region of the jaw and compromised sites.

• Journal of the Korean Geosynthetics Society
• /
• v.16 no.4
• /
• pp.151-161
• /
• 2017

A TSL (Thin Spray-on Liner) has a higher initial strength and faster construction time than conventional cementitious shotcrete. Because of its high adhesion and tensile strength, the TSL reinforced concrete show a characteristic like composite materials. In this study, to consider an application to the conventional design method, ASD (allowable stress design), numerical study was used. In the numerical analysis, material and contact properties were adopt from previous studies. Then a thickness of concrete in the tunnel was evaluated with the TSL reinforced case by the ASD concept. In other words, bending compressive stress, bending tensile stress and shearing force of the concrete were considered to determine a thickness of concrete lining by the given boundary conditions. From the numerical analysis, there was no tendency to show by the ASD because the ASD is based on the elastic theory while the TSL typically contributes to reinforcement after yielding.

• Polymer(Korea)
• /
• v.30 no.5
• /
• pp.445-452
• /
• 2006

In this study, we investigated interaction of Schwann cells (SCs) with various cell-adhesive coated polymer surface. We used cell-adhesives that like a fibronectin (FN), fibrinogen(FG), laminin(LM), vitronectin (VN), poly-D-Iysine (PDL), and poly-L-Iysine (PLL) to coat PLGA film surface and evaluated the surface property of coated or not PLGA films by measurement of water contact angle and ESCA. SCs were cultured on coated or non-coated PLGA film surface, and then examined the cell adhesion and proliferation by cell count and SEM observation. Cell count results revealed initial cell adhesion related to protein adsorption on PLGA surface. In addition, serum content in media related to cell proliferation rate. In this result, we recognized that adhesion and proliferation of SCs were affected by specific cell-adhesives. In these results, we recognized that is important to provide the suitable surface environment according to cell types and culture condition for improvement of cell adhesion and proliferation.

• Clean Technology
• /
• v.26 no.2
• /
• pp.122-130
• /
• 2020

The isotherm, kinetic, and thermodynamic parameters of reactive blue 4 adsorbed by activated carbon were investigated for activated carbon dose, pH, initial concentration, contact time, and temperature data. The adsorption of the RB 4 dye by activated carbon showed a concave shape in which the percentage of adsorption increased in both directions starting from pH 7. The isothermal adsorption data were applied to Langmuir, Freundlich, and Temkin isotherms. Both Freundlich and Langmuir isothermal adsorption models fit well. From determined Freundlich separation factor (1/n = 0.125 ~ 0.232) and Langmuir separation factor (R_L = 1.53 ~ 1.59), adsorption of RB 4 by activated carbon could be employed as an effective treatment method. The constant related to the adsorption heat (B_T = 2.147 ~ 2.562 J mol^-1) of Temkin showed that this process was physical adsorption. From kinetic experiments, the adsorption process followed the pseudo second order model with good agreement. The results of the intraparticle diffusion model showed that the inclination of the first straight line representing the surface diffusion was smaller than that of the second straight line representing the intraparticle pore diffusion. Therefore, it was confirmed that intraparticle pore diffusion is the rate-controlling step. The negative Gibbs free energy change (ΔG = -3.262 ~ -7.581 kJ mol^-1) and the positive enthalpy change (ΔH = 61.08 kJ mol^-1) indicated the spontaneous and endothermic nature of the adsorption process, proving this process to be spontaneous and endothermic.

• Polymer(Korea)
• /
• v.32 no.1
• /
• pp.70-76
• /
• 2008

The PES-g-BTCA membrane was synthesized by UV irradiation method and then used to be modified into the PES anion exchange membrane by the amination reaction. Their chemical structures and adsorption properties were investigated. The degree of grafting and amination were increased with increasing the reaction time and had the maximum values of 138% and 1.20 mmol/g at 80 min, respectively. The initial thermal degradation temperature of PES membrane was $400^{\circ}C$. Which was reduced as the surface modification reaction had proceeded. The values of contact angle for PES membrane were decreased from 68.1 to $40.2^{\circ}$ with increasing the extent of amination, the water up-take and ion exchange capacity were also increased with increasing UV irradiation time until 80 min. The average pore size and BET surface area were decreased in order of PES, PES-g-BTCA, and aminated PES ion exchange membrane. Their average pore sizes were 624.8, 359.7, and 138.5 ${\AA}$, and their surface areas were 10.1,9.7 and 1.7 $m^2/g$, respectively.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.44 no.1
• /
• pp.89-94
• /
• 2018

In this study, water-dispersed biocellulose nanofibers (TC) were prepared via an oxidation reaction using 2,2,6,6-tetramethyl-1-piperidine-N-oxy radical (TEMPO) as a catalyst. The TC retained their unique structure in water as well as in emulsion. TC adhered to the skin surface while maintaining nanofibrous structures, providing inherent functions of biocellulose, such as high tensile strength and high water-holding capacity. When gelatin gels as model skin were coated with TC, the hardness representing the elasticity was increased by 20% compared to untreated gelatin gel because TC could tightly hold the gelatin structure. When porcine skin was treated with TC and TC-contained O/W emulsion, the initial water contact angles of TC were lower than other materials, and dramatically decreased over time as water penetrated the fibrous structure of the TC film. Characterization of TC on the skin surface offered insight into the function of nanofibers on the skin, which is important for their applications with respect to fiber-cosmetics.