• The Journal of Korean Academy of Prosthodontics
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• v.52 no.1
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• pp.1-8
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• 2014

Purpose: The purpose of this study is to evaluate the effect of applying Silano-pen to feldspathic porcelain and zirconia on shear bond strength with composite resin. Materials and methods: Feldspathic porcelain and zirconia specimens were produced into 30 per each 2 mm thick and 12 mm in diameter and their surface was made smooth and even and then embedded in acrylic resin. The specimens were divided into each Group F (Feldspathic porcelain) and Group Z (Zirconia), (1) Hydrofluoric acid etching and silane (F1 & Z1), (2) Silano-pen and silane (F2 & Z2), (3) Hydrofluoric acid etching and Silano-pen, silane (F3 & Z3). After surface conditioning, substrate surfaces of the specimen were examined by SEM. Composite resin cylinders (2 mm high, 3 mm in diameter)were bonded to specimen and shear bond strength between ceramic and composite resin was measured by using universal testing machine. The measured values were statistically analyzed by using two way ANOVA and Tukey's multiple comparison test (${\alpha}=.05$). Results: In the scanning electron micrograph of the treated ceramic surface, Group F2 and F3 appeared the high roughness and Group Z3 appeared the highest density of silica particle. In Feldspathic porcelain, the result of measuring shear bond strength showed that Group F3 was measured to be highest and Group F1 was measured to be lowest but there was no statistical significance among Groups. In zirconia, Group Z3 was measured to be highest and Group Z1 was measured to be lowest and there was statistical significance among Groups (P<.05). Conclusion: In zirconia, applying hydrofluoric acid etching and then Silano-pen and silane is effective for composite resin adhesion.

• Journal of Periodontal and Implant Science
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• v.30 no.2
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• pp.213-231
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• 2000

이 연구의 목적은 다공성의 CPP 내부에 쥐의 장골의 골수에서 유래된 세포를 접종하고 3차 원적으로 배양하여 CPP가 골 형성을 위한 조직공학의 지지체로 적용가능한가를 연구하는 것과 Calcium PolyPhosphate(CPP)의 돌연변이 유발성을 검사하는 것이다. 무수 ($Ca(H_2PO_4)$)를 condensation하여 무결정의 ($Ca(PO_3)$)를 얻고 이를 용융하고 냉각시킨 후 분쇄하여 Calcium polyphosphate(CPP) powder를 얻었다. 다공성의 CPP는 5% $SiO_2$를 첨가하여 sponge 형태로 $450-550{\mu}m$ 소공의 크기를 가지는 것과(CPP-45ppi) $200-300{\mu}m$의 소공의 크기를 가지는 것(CCP-60ppi) 2가지로 제작하였다. 각각의 CPP matrices는 $5mm{\times}5mm{\times}1mm$의 블록 형태로 만들었다. 체중 100g 내외의 백서에서 장골(femur, tibia)을 채취하여 백서의 장골 골수 세포를 분리하여 배양한 후 24well에 CPP block을 넣고 CPP block 당 $10^5$개의 배양한 세포를 접종하였다. 배양 1, 7, 14, 및 21 일째에 각 well에서 trypsin EDTA를 이용하여 2회 반복하여 cell을 분리하였고, 원심분리한 후 hemacytometer로 측정하였다. 또, 45ppi와 60ppi, 그 리 고 Tissue Culture Polystyrene(control group)에 접종, 배양된 세포들의 염기성 인산분해효소활성도를 배양 7, 14, 및 21 일째에 각각 측정하였다. 각 기간별로 배양된 세포-CPP 혼합체내에서 세포의 부착 및 증식과 형성된 조직의 3차원적 형태를 관찰하기 위하여 주사전자현미경하에서의 관찰하였다. CPP의 돌연변이 유발성 검사 (mutagenicity test)를 위해 hypoxanthine-guanine phosphoribosyl transferase(HPRT) assay를 하였다. NIH3T3 cell line과 CHO-K1 cell line으로 각각 $1000{\mu}g/m{\ell}$, $100{\mu}g/m{\ell}$, $10{\mu}g/m{\ell}$ 그리고 $1{\mu}g/m{\ell}$의 CPP 농도에서 측정하였다. 통계적 분석을 위해서 모든 측정은 각군당 4개체 이상 시험하였고, 각 측정값은 평균값${\pm}$표준편차로 나타내었다. 각 군간의 통계적 유의성 검정을 위해서 Analysis of variance(ANOVA)를 이용하였고 Tukey의 방법으로 사후분석을 실시하였다. 제작된 CPP matrices 소공들이 서로간에 연결이 잘 되어있는 형태였다. 두 가지로 제조된 CPP(45ppi와 60ppi) 모두에서 세포의 부착이 잘 일어났고, 부착된 세포의 분열도 잘 일어났다. 2 가지의 CPP 모두에서 7, 14, 21일째의 세포 수는 1일째에 비해 유의성 있게 증가하였다(P<0.01). 3차원적 구조인 Calcium PolyPhosphate에서 배양한 세포는 24well dish(tissue culture polystyrene)에서 평면적으로 배양한 대조군의 세포에서 보다 염기성 인산분해효소 (Alkaline Phosphatase)를 유의성 있게 높게 나타냈다. 주사전자현미경에서 세포-CPP 혼합체를 관찰한 결과, CPP block에 세포들이 잘부착되어 있었고, 시간이 지남에 따라 세포가 여러 층을 형성하면서 뭉치는 현상을 보였다. 또, HPRT assay 결과 , Calcium PolyPhosphate는 돌연변이 유발성을 보이지 않았다. 이상의 결과로 볼 때 CPP에는 세포부착이 잘 일어나고, 지지체 상에서 세포의 분열도 활발하게 일어나므로 골조직을 위한 조직공학의 우수한 지지체가 될 수 있을 것으로 사료된다.

• Journal of the Korean Vacuum Society
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• v.16 no.5
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• pp.322-329
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• 2007

The interaction of oxygen with the ordered $Ni_3Al(111)$ alloy surface at 800 K and 1000 K has been investigated using LEED, STM, HREELS, UPS, and PAX. The clean $Ni_3Al(111)$ surface exhibits a "$2{\times}2$" LEED pattern corresponding to the ordered bulk-like terminated surface structure. For an adsorption of oxygen at 800 K, LEED shows an unrelated oxygen induced superstructure with a lattice spacing of $2.93\;{\AA}$ in addition to the ($1{\times}1$) substrate spots. The combined HREELS and the UPS data point to an oxygen chemisorption on threefold aluminum sites while PAX confirms an islands growth of the overlayer. Since such sites are not available on the $Ni_3Al(111)$ surface, we conclude the buildup of an oxygen covered aluminum overlayer. During oxygen exposure at 1000 K, however, we observe the growth of ${\gamma}'-Al_2O_3$ structure on the reordered $Ni_3Al(111)$ substrate surface. This structure has been identified by means of HREELS and STM. The HREELS data will show that at 800 K the oxidation shows a very characteristic behavior that cannot be described by the formation of an $Al_2O_3$ overlayer. Moreover, the STM image shows a "Strawberry" structure due to the oxide islands formation at 1000 K. Conclusively, from the oxygen interaction with $Ni_3Al(111)$ alloy surface at 800 K and 1000 K an islands growth of the aluminum oxide overlayer has been found.

• Applied Microscopy
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• v.29 no.4
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• pp.479-491
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• 1999

This study was performed to investigate the distribution and differentiation of choline acetyltransferase (ChAT)-immunoreactive cells in the basal nucleus of Meynert of the postnatal and adult rat forebrains, utilizing techniques of immunocytochemistry. According to the cell shape and the ratio of long axis vs short axis of cell soma, the ChAT-immunoreactive nerve cells in the basal nucleus of Meynert of the adult rat were classified into six types. In the adult rat, the frequency distributions (FD) of round, oval, elongated, fusiform, triangular and polygonal cells were 9.4%, 35.5%, 32.1%, 5.9%, 9.1% and 8.0%, respectively. The FD of oval and round nerve cells on the postnatal day (PND) 14 were observed to be 18.7% and 51.5%, respectively. Those were shown to be progressively decreased during developmental process to the adult. Also, those of elongated and triangular nerve cells on the PND 21 were observed to be 30.4% and 10.1%, respectively. Those were shown to be same phenomenon a,1 those in the round and oval cells. Meanwhile, those of the triangular and polygonal nerve cells were progressively increased from the early postnatal stage to the adult. The total mean volumes of ChAT-immunoreactive cell somata in the PND 7 rat were the lowest $(1,083{\mu}m^3)$ and those in the PND 21 rat were shown to be the highest $(5,045{\mu}m^3)$. But in the adult, those were decreased to $(2,731{\mu}m^3)$. Those in the PND 21 rat were shown to be about 84.7% larger than those in the adult. On the electron micrography, the cell organelles such as ribosomes, polysomes, rough endoplasmic reticula (RER) and mitochondria were well developed in the PND 21 rat forebrains, but Golgi complexes were shown to be proliferating phase. Especially, ribosomes, polysomes and RER were immunoreactive in the tissues treated with 0.05% triton X-100. According to the observations in the present study, it is considered that the ChAT-immunoreactive nerve cells in the basal nucleus of Meynert of the rat forebrains are differentiated throughout the following processes of changes during the postnatal development: 1) increase of cell soma volumes with the differentiation of tell organelles and neurites, 2) increase in the FD of differentiated tell types and 3) cell schrinkage without cell loss. The ribosomes, polysomes and RER are considered to be closely related to the intracellular localization and biosynthesis of the ChAT but not Colgi complex.

• Journal of Animal Science and Technology
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• v.51 no.4
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• pp.337-342
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• 2009

The feasibility of reutilization of magnesium ammonium phosphate (MAP) or struvite slurry recovered from the process through microwave irradiation was studied in this experiment. For this purpose, 4 different operations were performed with or without Mg source addition and different levels of MAP recycled in a batch reactor. Dissolution rate of MAP, ${NH_4}^+$ elimination pattern and physicochemical changes of MAP during microwave irradiation were also studied. The result showed that only 33% orthophosphate ($PO_4-P$) and 27% $NH_4-N$ removal occurred without adding any external Mg source (run A), whereas 87% $PO_4-P$ and 40% $NH_4-N$ removed when 1.0 M ratio of $MgCl_2$ (run B) was added based on $PO_4-P$ in influent. Although the addition of 1.0 molar ratio of microwave irradiated MAP (Run C) removed lower $PO_4-P$ and $NH_4-N$ than 1.0 M $MgCl_2$ (run B), $PO_4-P$ removal was double when compared with no Mg addition (run A). Addition of half MAP and half $MgCl_2$ (run D) showed the similar removal efficiency (88% $PO_4-P$ and 35% $NH_4-N$) with sole $MgCl_2$ addition (run B). Based on these results, the reutilization of MAP irradiated by microwave would be a feasible way to enhance the removal efficiencies of N and P, as well as curtail the Mg chemical usage. Track study showed that $NH_4-N$ gradually increased at initial stage of microwave irradiation of MAP, and then started eliminating from liquor as temperature increased over $45^{\circ}C$. Dissolution rate of ${PO_4}^{-3}$ during microwave irradiation was proportional to the initial MAP concentration, having $0.0091x^{0.6373}$ mg/sec. It was found from the scanning electron microscope (SEM) study that physical structure of MAP crystal started breaking down into small cube granules within very short time by electromagnetic vibration force during microwave irradiation and then gradually melted down into solution.

• Tuberculosis and Respiratory Diseases
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• v.50 no.2
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• pp.205-212
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• 2001

Background : The information on nasal transport and the metabolism of peptides have been obtained from pharmacokinetic investigations in experimental animals. However, there are no transport and metabolic studies of human nasal epithelial cells. In this study, the permeability characteristics and the metabolic properties of in vitro human nasal cell monolayers were investigated. Material and Methods : Normal human inferior nasal conchal tissue samples were obtained from patients undergoing endoscopic nasal cavitary surgery. The specimens were cultured in a transwell using an air-liquid Interface (ALI) culture, and the transepithelial electrical resistance (TEER) value of the blank filter and confluent cell monolayers were measured. To determine the % leakage of mannitol, $4{\mu}mol%$ $^{14}C$-labelled mannitol was added and the % leakage was measured every 10 minute for 1 hour. Result : Human nasal epithelial cells in the primary culture grew to a confluent monolayer within 7 days and expressed microvilli. The tight junction between the cells was confirmed by transmission electron microscopy. The TEER value of the blank filter, fifth day and seventh day reached $108.5\;ohm.cm^2$, $141\;ohm.cm^2$ and $177.5\;ohm.cm^2$, respectively. Transcellular % leakage of the $^{14}$-mannitol at 10, 20, 30, 40, 50 and 60 minutes was $35.67{\pm}5.43$, $34.42{\pm}5.60$, $32.75{\pm}5.71$, $31.76{\pm}4.22$, $30.96{\pm}3.49$ and $29.60{\pm}3.68\;%$, respectively. Conclusion : The human nasal epithelial monolayer using ALI culture techniques is suitable for a transcellular permeability study. The data suggests that human nasal epithelial cells In an ALI culture technique shows some promise for a nasal transport and metabolism study.

• Journal of the Korean Chemical Society
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• v.33 no.5
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• pp.558-567
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• 1989

The synthesis of methanol from carbon dioxide and hydrogen was studied for various compositions of Cu/ZnO catalyst system. Effect of the composition ratio of CuO and ZnO on the catalytic activity in the above reaction and the relationship between the activity and the characteristics of the catalysts were explained from the result of surface area measurements, SEM, XRD, and XPS. The major products of the reaction were methanol and carbon monoxide. The selectivity to methanol increased with increase of the copper oxide content in the catalyst up to CuO: ZnO = 30:70 weight ratio, and decreased rapidly when the content is above 70%. SEM and BET measurements, indicate that this point corresponds to the increasing point of the catalyst crystallite size and the decreasing point of the surface area. As to the Cu/Cu + Zn atomic ratio, the surface concentration of copper measured by XPS decreased remarkably when the copper oxide content in catalyst was higher than 50%. All the unreduced catalysts had almost same binding energy of Cu(2P3) level, but the binding energy for $Cu(2P^3)$ level of reduced catalysts was lowered than that of calcined catalysts. The surface copper species which was in the maximum amount when the CuO:ZnO composition in the catalyst was 30:70, existed as zero valent copper. This result agreed with the experimental result that the highest rate of methanol formation was observed when the CuO content in the catalyst was 30%. It was postulated that these reduced catalysts performed with a relatively strong basicity because the formation rate of acetone was higher than that of propylene in isopropanol decomposition as measured in a pulse type reactor.

• Journal of Oral Medicine and Pain
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• v.32 no.2
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• pp.137-150
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• 2007

Trees emit phytoncide into atmosphere to protect them from predation. Phytoncide from different trees has its own unique fragrance that is referred to as forest bath. Phytoncide, which is essential oil of trees, has microbicidal, insecticidal, acaricidal, and deodorizing effect. The present study was performed to examine the effect of phytoncide on Porphyromonas gingivalis, which is one of the most important causative agents of periodontitis and halitosis. P. gingivalis 2561 was incubated with or without phytoncide extracted from Hinoki (Chamaecyparis obtusa Sieb. et Zucc.; Japanese cypress) and then changes were observed in its cell viability, antibiotic sensitivity, morphology, and biochemical/molecular biological pattern. The results were as follows: 1. The phytoncide appeared to have a strong antibacterial effect on P. gingivalis. MIC of phytoncide for the bacterium was determined to be 0.008%. The antibacterial effect was attributed to bactericidal activity against P. gingivalis. It almost completely suppressed the bacterial cell viability (>99.9%) at the concentration of 0.01%, which is the MBC for the bacterium. 2. The phytoncide failed to enhance the bacterial susceptibility to ampicillin, cefotaxime, penicillin, and tetracycline but did increase the susceptibility to amoxicillin. 3. Numbers of electron dense granules, ghost cell, and vesicles increased with increasing concentration of the phytoncide, 4. RT-PCR analysis revealed that expression of superoxide dismutase was increased in the bacterium incubated with the phytoncide. 5. No distinct difference in protein profile between the bacterium incubated with or without the phytoncide was observed as determined by SDS-PAGE and immunoblot. Overall results suggest that the phytoncide is a strong antibacterial agent that has a bactericidal action against P. gingivalis. The phytoncide does not seem to affect much the profile of the major outer membrane proteins but interferes with antioxidant activity of the bacterium. Along with this, yet unknown mechanism may cause changes in cell morphology and eventually cell death.

• Restorative Dentistry and Endodontics
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• v.32 no.3
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• pp.208-221
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• 2007

The fracture toughness test is believed as a clinically relevant method for assessing the fracture resistance of the dentinal restoratives. The objectives of this study were to measure the fracture toughness $(K_{1C})$ and microtensile bond strength of dentin-resin composite interface and compare their relationship for their use in evaluation of the integrity of the dentin-resin bond. A minimum of six short-rod specimens for fracture toughness test and fifteen specimens for microtensile bond strength test was fabricated for each group of materials used. After all specimens storing for 24 hours in distilled water at $37^{\circ}C$, they were tensile-loaded with an EZ tester universal testing machin. Statistical analysis was performed using ANOVA and Tukey's test at the 95% confidence level, Pearson's coefficient was used to verify the correlation between the mean of fracture toughness and microtensile bond strength. FE-SEM was employed on fractured surface to describe the crack propagation. Fracture toughness value of Clearfil SE Bond (SE) was the highest, followed by Adper Single Bond 2 (SB), OptiBond Solo (OB), ONE-STEP PLUS (0S), ScotchBond Multi-purpose (SM) and there was significant difference between SE and other 4 groups (p < 0.05). There were, however, no significant difference among SB, OB, OS, SM (p > 0.05). Microtensile bond strength of SE was the highest, followed by SB, OB, SM, OS and OS only showed significant lower value (p < 0.05). There was no correlation between fracture toughness and microtensile bond strength values. FE-SEM examination revealed that dentin bonding agent showed different film thickness and different failure pattern according to the film thickness. From the limited results of this study, it was noted that there was statistically no correlation between K1C and ${\mu}TBS$. We can conclude that for obtaining the reliability of bond strength test of dentin bonding agent, we must pay more attention to the test procedure and its profound scrutiny.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.699-720
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• 1995

This study was conducted to evaluate the effect of benzalkonium chloride solution as a wetting agent instead of water on dentin bonding with NTG-GMA/BPDM system (All-bond 2, Bisco.) and DSDM system (Aelitebond, Bisco.). Benzalkonium chloride solution is a chemical disinfectant widely used in medical and dental clinics for preoperative preparation of skin and mucosa due to its strong effect of cationic surface active detergent. Eighty freshly extracted bovine lower incisor were grinded labially to expose flat dentin surface, and then were acid-etched with 10 % phosphoric acid for 15 second, water-rinsed, and dried for 10 second with air syringe. The specimens were randomly divided into 8 groups of 10 teeth. The specimens of control group were remoistured with water and the specimens of experimental groups were remoistured with 0.1 %, 0.5 %, and 1.0 % benzalkonium chloride solution respectively. And then, the Aelitefil composite resin was bonded to the pretreated surface of the specimens by use of All-bond 2 dentin bonding system or Aelitebond dentin bonding system in equal number of the specimens. The bonded specimens were stored in $37^{\circ}C$ distilled water for 24 hours, then the tensile bond strength was measured, the mode of failure was observed, the fractured dentin surface were examined under scanning electron microscopy, and FT-IR spectroscopy was taken for the purpose of investigating the changes of the dentin surface pretreated with benzal konium chloride solution followed by each primer of the dentin bonding systems. The results were as follows : In the group of bonding with NTG-GMA/BPDM dentin bonding agent(All-bond 2), higher tensile bond strength was only seen in the experimental group remoistured with 0.1 % benzal konium chloride solution than that in water-remoistured control group(p<0.05). In the group of bonding with DSDM dentin bonding agent (Aelitebond), no significant differences were seen between the control and each one of the experimental group(p<0.05). Higher tensile bond strength were seen in NTG-GMAIBPDM dentin bonding agent group than in DSDM dentin bonding agent group regardless of remoistur ization with benzal konium chloride solution. On the examination of failure mode, cohesive and mixed failure were predominantly seen in the group of bonding with NTG-GMAIBPDM dentin bonding agent, while adhesive failure was predominantly seen in the group of bonding with DSDM dentin bonding agent. On SEM examination of fractured surfaces, no differences of findings of primed dentin surface between the groups with and without remoisturization with benzal konium chloride solution. FT-IR spectroscopy taken from the control and the experimental group reve::.led that some higher absorbance derived from the primers binding to dentin surface was seen at the group pretreated with 0.1 % benzal konium chloride solution than at the control group of remoisturizing with water.