• 대한치과교정학회지
• /
• 제46권6호
• /
• pp.386-394
• /
• 2016

Objective: The objective of the study was to evaluate the practicality and the validity of different surface treatments of self-drilling orthodontic mini-implants (OMIs) by comparing bone cutting capacity and osseointegration. Methods: Self-drilling OMIs were surface-treated in three ways: Acid etched (Etched), resorbable blasting media (RBM), partially resorbabla balsting media (Hybrid). We compared the bone cutting capacity by measuring insertion depths into artificial bone (polyurethane foam). To compare osseointegration, OMIs were placed in the tibia of 25 rabbits and the removal torque value was measured at 1, 2, 4, and 8 weeks after placement. The specimens were analyzed by optical microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Results: The bone cutting capacity of the etched and hybrid group was lower than the machined (control) group, and was most inhibited in the RBM group (p < 0.05). At 4 weeks, the removal torque in the machined group was significantly decreased (p < 0.05), but was increased in the etched group (p < 0.05). In the hybrid group, the removal torque significantly increased at 2 weeks, and was the highest among all measured values at 8 weeks (p < 0.05). The infiltration of bone-like tissue surface was evaluated by SEM, and calcium and phosphorus were detected via EDS only in the hybrid group. Conclusions: Partial RBM surface treatment (hybrid type in this study) produced the most stable self-drilling OMIs, without a corresponding reduction in bone cutting capacity.

• 한국염색가공학회지
• /
• 제17권6호
• /
• pp.36-41
• /
• 2005

The effects of low temperature plasma treatment on the properties of three types of foams, polyurethane(PU), injection phylon(IP), and phylon(PH) that used for footwear mid-sole were examined. The change of surface properties of foams were characterized by electron scanning microscope, contact angle measurement, and universal testing machine. Adhesion was tested by T-peel tests of plasma treated foams/polyurethane adhesive joints. The contact angle of three types of foams were decreased dramatically with the plasma treatment time, specifically noticeable in the case of phylon(Ph). It has shown the relationship with the contact angle of phylon(PH) and the distance between electrode and samples. The peel strength of foams were increased with the increase of plasma treatment time.

• 한국응용과학기술학회지
• /
• 제25권1호
• /
• pp.23-31
• /
• 2008

In general, anionic and cationic surfactants are incompatible because their mixtures form insoluble complexes. There are, however, some complexes that are soluble and behave like regular surfactants, specifically like nonionic surfactants, thus named pseudo-nonionic surfactant complexes. Pseudo-nonionic complexes are more effective and efficient than their ionic surfactant components as shown by their equilibrium and dynamic surface tensions and interfacial tensions. They pack at the interface more than their ionic components. Since, pseudo-nonionic complexes show their own characteristics, they can be treated as separate classes of surfactants distinct from ionic and nonionic surfactants. Novel cationic surfactant was synthesized, having the polyhydroxyl group at the head group. We found that aqueous mixtures of our cationic surfactant and usual anionic surfactant(SDS) could form homogeneous solutions even at high concentration. The properties of mixed surfactant solutions were measured. Foam stability, CMC(critical micelle concentration), water hardness tolerance and thickening effect were tested. The foam stability of mixed surfactants was very good and various synergy effects were observed.

• 한국재료학회지
• /
• 제12권6호
• /
• pp.442-446
• /
• 2002

Design of microwave absorbers using high frequency properties of fiber reinforced composites are investigated. Two kinds of composite materials (glass and carbon) are used and their complex permittivity and permeability are measured by transmission/reflection technique using network analyzer. Low dielectric constant and nearly zero dielectric loss are determined in glass fiber composite. However, carbon fiber composites show the high dielectric constant and large conduction loss which is increased with anisotropy of fiber arrangement. It is, therefore, proposed that the glass and carbon fiber composites can be used as the impedance transformer (surface layer) and microwave reflector, respectively. By inserting the foam core or honeycomb core (which can be treated as an air layer) between glass and carbon fiber composites, microwave absorption above 10 dB (90% absorbance) in 4-12 GHz can be obtained. The proposed fiber composites laminates with sandwitch structure have high potential as lightweight and high strength microwave absorbers.

• 대한치과교정학회지
• /
• 제41권4호
• /
• pp.268-279
• /
• 2011

본 연구의 목적은 유지력을 높이기 위하여 교정용 미니 임플랜트에 표면처리를 시행하되 식립 과정의 용이성에 영향을 주지 않는 표면처리 방법을 찾기 위함이다. 교정용 미니 임플랜트를 etching, resorbable blasting media (RBM), 상부 나사산 부위만 RBM 처리를 한 hybrid 등의 3가지 방법으로 표면처리한 후 machined (표면 미처리)군과 비교하였다. 주사전자현미경과 표면 거칠기 측정기로 표면 거칠기를 비교하였으며, driving torque tester를 이용해 실험용 인공골에 교정용 미니 임플랜트를 식립하여, 식립 토크(rotational torque)와 수직력(vertical loading)의 식립 패턴을 비교하였다. Machined surface군과 비교하여 acid etching군에서는 표면 거칠기(Ra 값)가 크지 않았으나 ($p$ > 0.05), RBM군이나 hybrid군에서 표면 거칠기(Ra 값)가 유의하게 컸다 ($p$ < 0.05). 최종 식립 토크는 모든 표면처리군에서 machined군보다 컸다 ($p$ < 0.05). 최대 식립수직력은 hybrid군이 machined군이나 etched군보다 유의하게 작았으며 ($p$ < 0.05), RBM군이 가장 컸다 ($p$ < 0.05). 교정용 미니 임플랜트의 유지력을 높이기 위하여 보철용 임플랜트와 같은 방법으로 전면 표면처리를 하면 self drilling type 고유의 골 삭제기능이 저하될 수 있다. 그러나 cutting edge 일정 부위를 제외하며 적절하게 조절된 표면처리를 하면 골 삭제 능력의 큰 저하 없이 용이한 식립이 가능할 것으로 보인다.

• 한국재료학회지
• /
• 제12권6호
• /
• pp.458-463
• /
• 2002

Carbon nanotubes were synthesized at various conditions using Ni-catalytic thermal chemical vapor deposition method and their characteristic properties were investigated by SEM, TEM and Raman spectroscopy. Carbon nanotubes were formed on very fine Ni-catalytic particles. The carbon nanotubes synthesized by thermal decomposition of acetylene at $700^{\circ}C$ had a coiled shape, while those synthesized at $850^{\circ}C$ showed a curved and Y-shape having a bamboo-like morphology. It was found that the carbon nanotube was also made on the fine Ni-catalytic particles formed on the surface of 100~400nm sized large ones after pretreatment with $NH_3$.ber composites show the high dielectric constant and large conduction loss which is increased with anisotropy of fiber arrangement. It is, therefore, proposed that the glass and carbon fiber composites can be used as the impedance transformer (surface layer) and microwave reflector, respectively. By inserting the foam core or honeycomb core (which can be treated as an air layer) between glass and carbon fiber composites, microwave absorption above 10 dB (90% absorbance) in 4-12 GHz can be obtained. The proposed fiber composites laminates with sandwitch structure have high potential as lightweight and high strength microwave absorbers.

• 대한의생명과학회지
• /
• 제22권4호
• /
• pp.220-226
• /
• 2016

Hypertriglyceridemia induces atherosclerosis and accordingly is a major causative factor in cardiovascular diseases. Macrophages that develop into foam cells are a crucial component in the development of atherosclerosis. Monocytes can be differentiated into M1 or M2 macrophages. M1 macrophages promote inflammatory responses, whereas M2 macrophages exhibit anti-inflammatory activity. Recently, we found that triglyceride (TG)-treated THP-1 monocytes express a variety of macrophage-specific surface markers, indicating that TG treatment could trigger the differentiation of monocytes into macrophages. In this study, we investigated whether TG-induced macrophages express the M1 or the M2 macrophage phenotype. THP-1 cells were treated with various concentrations of TG for different times and the expression of M1- and M2-specific markers was evaluated by RT-PCR. We found increased expression of M1 markers (CD40, CD80, and CD86) in TG-treated THP-1 cells in a TG dose- and time-dependent manner. The expression of M2 markers (CD163, CD200R, and CD206) showed variable responses to TG treatment. Taken together, our results indicate that TG treatment triggers the differentiation of monocytes into M1 macrophages, rather than into M2 macrophages, suggesting that TG contributes to pro-inflammatory responses.

• Journal of Animal Science and Technology
• /
• 제53권3호
• /
• pp.253-259
• /
• 2011

The aim of this work was to determine the method and predict the optimum conditions for egg quality stored for 7 days when combination treatments of irradiation and chitosan coating were applied using response surface methodology (RSM). A central composite design was chosen for the RSM in this study and the factors were irradiation dose (0~2 kGy) and concentration of chitosan coating material (0~2%). Performance of the irradiation and chitosan coating were evaluated by analyzing the egg quality and functional property factors. The predicted maximum level of Haugh units and foaming ability calculated by a developed model were 74.19 at 0 kGy of irradiation with coating by 0.96% chitosan solution and 50.83 mm at 2.0 kGy with 1.01%, respectively. The predicted minimum value of foam stability and 2-thiobarbituric acid reactive substances (TBARS) value were 2.97 mm at 0.39 kGy with 0.21% and 0.54 mg malonaldehyde/kg egg yolk at 0 kGy with 0.90% of chitosan solution, respectively. Results clearly showed that gamma irradiation negatively affected the Haugh unit and TBARS but positively affected the foaming capacity. The estimated value from the developed model by RSM was verified by no statistical difference with observed value. Therefore, RSM can be a good tool for optimization and prediction of egg quality when 2 or more treatments are combined. However, one should decide the target quality first to achieve a successful implementation of this technology.

• Archives of Plastic Surgery
• /
• 제34권5호
• /
• pp.587-592
• /
• 2007

Purpose: In case of postburn flexion contracture of the fingers, skin graft, geometrical relaxation techniques, local flap, and free flap have been used. Among these procedures, full-thickness skin grafts from the inguinal area are widely used to reconstruct a postburn flexion contracture in the fingers. But there are many esthetic and functional problems in this procedure. Especially, hyperpigmentation of the skin-grafted fingers poses a troublesome problem, particularly in the patients who have dark colored skin. To solve the problem, we have used pulp graft which was harvested from the lateral aspect of great toe. In the present study, we report pulp graft, with which we have obtained a good result in the treatment of postburn flexion contracture of the fingers. Methods: Between September of 2004 and August of 2006, great toe pulp graft was performed to 20 sites of 15 patients. After release of the postburn flexion contracture using Z-plasty, the composite tissue (pulp) harvested from the lateral aspect of great toe was grafted on the raw surface. Moisture dressing with ointment and foam dressing material was performed. Stratum corneum of the graft got stripped off in two to four weeks after pulp graft. The color of the pulp graft was slightly reddish, then it became similar to the adjacent tissue. Results: There was complete take in all the patients who were treated with pulp graft. Great toe pulp graft provided similar color and texture to the adjacent skin, high rate of graft take, and left only a minimal scar at donor site. Conclusion: Thick keratin layer and inelastic nature of the pulp make this type of the graft much easier and simpler, and ensure a better take. Pulp graft is useful method for the reconstruction of the postburn flexion contracture in fingers.

• 공업화학
• /
• 제34권1호
• /
• pp.30-35
• /
• 2023

TiO₂ 졸을 사용하여 유리알 표면에 TiO₂ 코팅한 후 건조 처리한 시료(TB)와 소성한 시료(TBc)를 제조하였다. 이들 시료에 대한 TiO₂ 박막의 특성분석과 메틸렌블루 및 톨루엔의 광분해 실험을 수행하였다. FE-SEM, XPS 및 FTIR 분석 결과, TB 시료의 TiO₂ 박막은 스펀지 폼과 같은 형태이며 무정형 TiO₂와 일부 결정형 TiO₂가 존재하였다. TBc 시료의 TiO₂ 박막에는 결정형 TiO₂가 주로 존재하며 침상형 입자와 미세 입자들이 혼재하였다. TBc 시료(46 mg/g)의 톨루엔 흡착량은 같은 코팅량의 TB 시료 대비 적었으나 톨루엔 분해율은 비슷했다. TB 시료의 경우, TiO₂ 코팅량이 증가함에 따라 톨루엔 분해능이 흡착능에 비해 적게 감소하였다. 이러한 결과는 소성하지 않은 TB 시료는 TiO₂ 코팅량이 증가하면 무정형 텍스처의 비표면적은 감소하는 반면 결정성 입자들의 활성점 감소는 적게 일어나기 때문으로 판단된다.