• Macromolecular Research
• /
• v.17 no.1
• /
• pp.37-43
• /
• 2009

To fabricate dental nanocomposites containing finely dispersed silica nanoparticles, nearly monodispersed silica nanoparticles smaller than 25 nm were synthesized without forming any aggregates via a modified sol-gel process. Since silica nanoparticles synthesized by the Stober method formed aggregates when the particle size is smaller than 25 nm, the synthetic method was modified by changing the reaction temperature and adding poly(1-vinyl-2-pyrrolidinone) (PVP) to the reaction mixture. The size of the formed silica nanoparticles was reduced by increasing the reaction temperature or adding PVP. Furthermore, the formation of aggregates with primary silica nanoparticles smaller than 25 nm was prevented by increasing the amount of PVP added to the reaction mixture. To enhance the dispersion of the silica particles in an organic matrix, the synthesized silica nanoparticles were treated with 3-methacryloxypropyltrimethoxysilane ($\gamma$-MPS). A dental nanocomposite containing finely dispersed silica nanoparticles could be produced by using the surface-treated silica nanoparticles.

• Bulletin of the Korean Chemical Society
• /
• v.6 no.1
• /
• pp.37-40
• /
• 1985

The electrical conductance and UV absorbance of 4,N-dimethyl Pridinium Iodide (NDMPI) were measured in the ethanol volume percentage, 95, 90, 80 and 60 of an ethanol-water mixture at 15, 25, 35 and $45^{\circ}C$. Ionic association constants(K) of NDMPI were evaluated in accordance with a combined method of conductance UV absorbance. The ion size parameter (${\gamma}_{\pm}$) and dipole momemt (${\mu}_{A+D-}$) of NDMPI were obtained from the values of K and dielectric constant. The ${\mu}_{A+D-}$- values were in good agreement with the values of transition moment(${\mu}_{mn}$) which is calculated form the UV peak values. The large negative values of the electrical enthalpy (${\Delta}H_{el}^{\circ}$) and entropy (${\Delta}H_{el}^{\circ}$ ) have proved that NDMPI had a positive hydration. The positive values of entropy (${\Delta}S^{\circ}$) means the formation of NDMPI ion goes with dehydration.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.185-188
• /
• 2008

We have analyzed the structures of $Alq_3$ in different polymorphs by solid-state NMR. On the basis of the results, OLEDs were fabricated from different polymorphs of $Alq_3$. The current efficiency of the device fabricated from the mixture of $\alpha$-, $\gamma$-, and $\delta-Alq_3$ powders was higher than that from $\alpha-Alq_3$.

• Journal of the Korean Ceramic Society
• /
• v.15 no.3
• /
• pp.135-139
• /
• 1978

Sintering oxide which was prepared by sintering at $1200^{\circ}C$ the mixture of ${\gamma}$-$Fe_2O_3$ and $Sb_2O_3$ in 2 : 1 mol ratio, showed 1st electrical switching and stable 2nd switching when D.C. voltage was applied. This electrical switching mechanism was known to be thermal mechanism from dependence of environmental temperature of threshold Voltage(Vm), Current(Im) and the conductivity of the current filament of the sintering oxide.

• Journal of the Korean Data and Information Science Society
• /
• v.20 no.5
• /
• pp.933-939
• /
• 2009

The bivariate data in clinical research fields often has two types of failure times, which are mark variable for the first failure time and the final failure time. This paper showed how to generate bootstrap data to get Bayesian estimation for the joint distribution of bivariate survival times. The observed data was generated by Frank's family and the fake date is simulated with the Gamma prior of survival time. The bootstrap data was obtained by combining the mimic data with the observed data and the simulated fake data from the observed data.

• Korean Journal of Acupuncture
• /
• v.34 no.2
• /
• pp.82-87
• /
• 2017

Objectives : Recently the case of lactobacillus mixture culture fluid appliment was reported. In this study, anti-inflamation effects and anti-allergy effects were studied by stimulus of lactobacillus mixture culture fluid extracts in HaCaT cells. Methods : The atopic dermatitis were induced by TNF-${\alpha}$ and interferon-${\gamma}$ in HaCaT cells. TARC/CCL17, MDC/CCL22, RANTES/CCL5 and ROS production were investigated to explain anti-inflamation and allergy effects of lactobacillus mixture culture fluid with cell-enzyme-linked Immunosorbent assay in 450 nm, 485 nm, 535 nm with spectro-fluorometer. Results : The extracts of lactobacillus mixture culture fluid were decreased TARC/CCL17, MDC/CCL22, RANTES/CCL5 expressions and ROS production with a concentration dependent manner. Conclusions : The effects mechanism of Lactobacillus mixed culture fluid for atopic dermatitis symptoms were considered to be explain anti-inflamation and allergy effects via control of cytokine, chemokine and ROS production, and the fluid could be applied in skin cells directly. But classified AD symptom degrees reported in clinical case before as Reaction Period, Reduction Period, Effect Period, Reproduction Period and Rebound Period could not be explained. Further study will be expected.

• Journal of the Korean Ceramic Society
• /
• v.39 no.5
• /
• pp.473-478
• /
• 2002

${\alpha}-Al_2O_3$ platelets were synthesized by microwave heating the two different powder mixtures of $Al_2(SO_4)_3+2Na_2SO_4$ and ${\gamma}-Al_2O_3+2Na_2SO_4$ using flux method. DTA-TG, XRD and SEM were used to investigate the effect of microwave on the formation of ${\alpha}-Al_2O_3$ platelets. In the case of the mixture of $Al_2(SO_4)_3+2Na_2SO_4$, the microwave heated sample was ${\alpha}-Al_2O_3$ platelets composed of aggregates with smaller particle size compared to the conventionally heated sample. In the case of the mixture of ${\gamma}-Al_2O_3+2Na_2SO_4$, the temperature to form ${\alpha}-Al_2O_3$ platelets by the microwave heating was lower than that by the conventional heating and the morphology of the microwave heated sample was similar to that of the conventionally heated sample except that the microwave heated sample had smaller particle size compared to the conventionally heated sample.

• Journal of the Korean Chemical Society
• /
• v.18 no.1
• /
• pp.40-46
• /
• 1974

The fission neutron reactions of $^{47}Ti(n.p)^{47}Sc$ and $^{93}Nb(n,{\alpha})^{90m}Y$, along with epicadmium neutron reaction of $^{96}Zr(n,{\gamma})^{97}Zr$ were used for the simultaneous determination of Ti, Nb and Zr in synthetic mixture. Prior to neutron irradiation, Ti, Zr and Nb in the mixture were separated together in one group through the cation exchange column of Dowex $50{\times}8$ resin using 0.5 M ${\alpha}$-hydroxy-iso-butyric acid as the eluent. After irradiation of the eluate the product nuclides, $^{97}Zr$, ^{47}Sc$ and ^{90m}Y$, were eluted sequentially through the same column with 0.5 M ${\alpha}$-HIBA, 0.5 M ${\alpha}$-HIBA-1 N HNO_3 and 0.5 M ${\alpha}$-HIBA-2 N HNO_3$ solution, respectively. The gamma-ray spectrometry was used for the measurement of the gamma-ray activities of the eluted nuclides. The detection limits of Nb, Ti and Zr were found to be 0.2 %, 0.01 % and 0.002 %, respectively.

• Journal of Soil and Groundwater Environment
• /
• v.6 no.4
• /
• pp.61-72
• /
• 2001

A barrier liner system is placed at the bottom and side slope in landfill to protect a leaking of leachate that the hydraulic conductivity of this system should be less than It 107cm/sec. In this study, the soil-bentonite mixture for the bottom liner system was evaluated in two point of views : changing characteristics of the hydraulic conductivity according to the different mixing ratio of soil-bentonite with the effect of bentonite swelling and the difference method (A & D type) of compaction on the hydraulic conductivity. As the results, maximum dry density (${\gamma}$$_{dmax}$) of SC group mixture was higher than of CL group mixture. However, the result of optimum moisture contents(OMC) of both groups were the contrary. In case of ${\gamma}$$_{dmax}$ by different compaction method, D type was higher than A. But the OMC were the contrary. The difference of ${\gamma}$$_{dmax}$ according to the Compaction energy, “SC” group mixture W3S higher than the “CL” group. In case of OMC of “CL” group was higher than “SC” group. The effecting of swelling was a little bit different on the two factors. According to the result of compaction test, the use of site soil only could not meet the criteria on hydraulic conductivity, but could find a solution for the mixing ratio of bentonite mixture were satisfied to the standard of barriation. The increased in bentonite mixing ratio and degree of swelling, the values of hydraulic conductivity were decreased. Especially the “CL” group with “D” type compaction measured the lowest value with the same conditions. Also, the bentonite mixing ratio has more influenced on the hydraulic conductivity compare with swelling effect. The “SC” group mixture with “A” typo compaction got a big difference from others. The evaluation of economic for the construction cost on the two cases, the lower bentonite mixing ratio of soil-bentonite mixed soil is more economically because of bentonite cost.

• Journal of Pharmacopuncture
• /
• v.13 no.1
• /
• pp.53-61
• /
• 2010

Purpose : To investigate the effects of the lavender, lemon and eucalyptus oil mixture on the atopy dermatitis skin lesions induced on NC/Nga Mice by dinitrochlorobenzene (DNCB). Material and Method : For this purpose, we fabricated the oil mixture blending three essential oils (lavender, lemon, eucalyptus : ELL) with one carrier oil (jojoba) and apply it on the atopic dermatitis skin lesions of NC/Nga Mice. Atopic dermatitis in NC/Nga Mice was induced by DNCB treatment on the dorsal skin of mice for 8 weeks. The mixture of ratio of each essential oil drop was 1 (eucalyptus) : 2 (lemon) : 2 (lavender) and this mixture was blended with jojoba oil 50ml (0.025%). The ELL-ointment was supplied for 8 weeks. We evaluated the effects of ELL on cell viability of mouse lung fibroblast, clinical skin features and severity, the level of serum Immunoglobulin (Ig) E & Ig G1, Interleukin (IL)-4, IL-13 and Interferon (IFN)-$\gamma$. Results : ELL showed safety on the cell viability of mouse lung fibroblast compared with control group. The cell viability was measured by SRB method. The effects of ELL on clinical skin features and severity in DNCB-induced dermatitis model of NC/Nga mice was significant compared with control group. EEL also showed significant effects on clinical symptom score compared with control group. Serum IgE & IgG1 level and development of atopy dermatitis skin lesions were evaluated. Serum IgE & IgG1 production was significantly down-regulated in EEL group compared with control group. ELL also down-regulated the levels of IL-4 and IL-13, and up-regulated the level of IFN-$\gamma$ compared with control group significantly. Conclusion : ELL was effective on atopy dermatitis by modulating Th2 related factors.