• Restorative Dentistry and Endodontics
• /
• 제20권1호
• /
• pp.152-163
• /
• 1995

This experiment was performed to observe the adhesion pattern and microleakage in the gingival margin according to variation in the resin cement thickness which results from thickness of Die spacer. which is considered to effect the adaptability of the composite resin inlays. Clearfil CR inlays were fabricated on stone models with CR Sep applicated once and Nice fit twice, 4 times, and 6 times each. After 2nd curing within the CRC-100 oven, CR inlays were cemented with CR inlay cement. Dye(2% methylene blue) penetration and adhesion pattern were evaluated after sectioning of gingival margin into :3 pieces. The results were as follows ; 1. The thickness of resin cement showed unevenchanging pattern with that of die spacer, namely, it was increased until 4 times' application of Nice-Fit but was decreased with 6 times' application of that. 2. The degree of dye penetration wasn't affected by cement thickness within a limited value. 3. Most of dye penetration was shown through the interface between cement and enamel rather than the interface between cement and CR inlay. This shows that the affinity of resin cement for CR inlay was superior to the adhesive strength with tooth structure. 4. No gap was found at the interface between enamel and cement but some showed separation between dentin and cement. It is concidered that the contraction force of cement was less than the bond strength with the enamel. 5. Lots of voids were found in the CR inlay and resin cement. There was a pooling tendency of bonding agent and cement in the axiogingival line angle portion. 6. In some specimens, cracks were shown in enamel margin. From this it could be considered that cavity preparation and surface treatment weakened the tooth structure.

• 분석과학
• /
• 제23권6호
• /
• pp.560-565
• /
• 2010

과염소산 이온($ClO_4^-$)은 로켓, 그리고 미사일 추진체등의 군사적 무기에 산화제로서 널리 사용이 되고 있다. 또한 주요 오염물질로 간주되는 과염소산 이온을 분해하려는 연구도 계속 진행이 되고 있다. 과염소산 이온을 환원 분해 처리하기위한 촉매로는 0가 철이 많이 응용되고 있다. 0가 철은 지표수의 정화나 오염물질의 처리에 널리 활용이 되고 있는 물질이다. 그러나 이것은 뭉침이 잘 일어나고 쉽게 침전이 되며 제한적인 유동성을 갖는 경향이 있다. 따라서 본 연구에서는 칼슘-알지네이트 고분자를 응용하여 나노크기의 0가 철 입자를 고정시켜 안정화하고 과염소산 이온을 환원분해 하였다. 안정화된 0가 철 입자는 분산되어 넓은 표면적을 가지기 때문에 과염소산 이온의 환원분해 효율을 더욱 증가 시킨다. 본 연구에서는 지지체 물질인 알지네이트 비드로 0가 철을 고정화하는 방법을 개발하고 가교제 역할을 하는 칼슘이온을 함께 사용하였다. 이것을 이용하여 과염소산 이온의 환원분해 효율을 온도를 변화하면서 실험 하였고 재사용 가능성을 점검하였다.

• Applied Biological Chemistry
• /
• 제29권3호
• /
• pp.241-247
• /
• 1986

쌀밥 품질의 영향 요인을 규명하기 위하여 밥 짓기 과정중 밥과 밥물의 상호 관계를 분석하고, 저급의 장립종 밀양 23호의 밥맛 증진의 수단으로 새로운 밥짓기 방법을 제시하였다. 밥짓기 과정중 밥과 밥물의 높이 변화를 측정하였다. 끊는점 부근에서 밥물이 급격히 감소하고, 이어서 농축된 밥물이 밥알 표면에 엷은 피막층을 형성함을 관찰할 수 있었다. 피막 보강 물질로 찹쌀분 1,2%(W/W)를 첨가 한 후 밥짓기를 향한 결과, 피막이 크게 보강되었으며 이렇게 제조된 밥은 윤기와 외관이 향상되고 수분 함량이 증가하였으며 밥짓기중 가용성 쌀 고용분 함량의 용출을 감소시킬 수 있었다. 밥알 피막의 형성은 밥짓기의 최종단계에서 밥알의 진동과 밥물의 고형분 농도와 유관함을 보였고, 밥의 음질 결정의 중요 요소로 작용할 수 있음을 제안하였다.

• Environmental Engineering Research
• /
• 제11권3호
• /
• pp.127-133
• /
• 2006

Aerobic floc-like sludge was formed in a batch reactor and the effect of cations on the formation of aerobic floc-like sludge was studied. In order to enhance the formation (rate) of aerobic floc-like sludge, cations such as $K^+$, $Na^+$, $Ca^{2+}$, and $Mg^{2+}$ were added to the seed sludge. It was found that $Ca^{2+}$ had positive effect on the formation of floc-like sludge, as measured by sludge volume index (SVI) for settle ability. The formation of floc-like sludge was confirmed by the microscopic observation after DAPI staining. The scattered forms of sludge samples at the initial stage became aggregated to form floes after $Ca^{2+}$ addition. To ensure the functions of sludge floes in a treatment plant, the gradient of ionic species around the surfaces of floc-like sludge was monitored by ion selective microelectrodes for ${NH_4}^+,\;{NO_3}^-$, and pH. The effective concentration of $Ca^{2+}$ ion to form floc-like sludge was determined to be 750 mg/L (0.15 mg $Ca^{2+}/mg$ MLSS). Under the effective $Ca^{2+}$ condition, the SVI value was the lowest and large distribution of nitrifying bacteria at the outer surface was observed in the aerobic floc-like sludge. From the results, it was found that the calcium ion functioned as an agent for the formation of aerobic floc-like sludge, resulting in the enhanced nitrification.

• The Korean Journal of Physiology and Pharmacology
• /
• 제10권5호
• /
• pp.251-254
• /
• 2006

Schizandrae Fructus has been used for controlling respiratory allergic or inflammatory diseases in folk medicine and their components, schizandrin, schizandrin-A and gomisin-A were reported to have diverse biological effects. In this study, we investigated whether schizandrin, schizandrin-A and gomisin-A affect adenosine triphosphate (ATP)-induced mucin secretion from cultured airway epithelial cells. Confluent primary hamster tracheal surface epithelial (HTSE) cells were metabolically radio labeled using $^{3}H-glucosamine$ for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on $^{3}H-mucin$ secretion. The results were as follows: 1) schizandrin significantly inhibited ATP-induced mucin secretion; 2) However, schizandrin-A and gomisin-A did not affect ATP-induced mucin secretion, significantly. We conclude that schizandrin can inhibit ATP-induced mucin secretion by directly acting on airway mucin-secreting cells. Therefore, schizandrin should further be investigated for the possible use as mucoregulators in the treatment of inflammatory airway diseases.

• The Korean Journal of Physiology and Pharmacology
• /
• 제10권6호
• /
• pp.317-321
• /
• 2006

In this study, we investigated whether glycyrrhizin, prunetin and morroniside affect mucin secretion from cultured airway epithelial cells and compared the possible activities of these agents with the inhibitory action on mucin secretion by poly-L-lysine (PLL) and the stimulatory action by adenosine triphosphate (ATP). Confluent primary hamster tracheal surface epithelial (HTSE) cells were metabolically radiolabeled using $^{3}H-glucosamine$ for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on $^{3}H-mucin$ secretion. The results were as follows: 1) glycyrrhizin and morroniside increased basal mucin secretion from airway; 2) prunetin did not affect basal mucin secretion; 3) glycyrrhizin did not inhibit ATP-induced mucin secretion. We conclude that glycyrrhizin and morroniside can increase basal mucin secretion, by directly acting on airway mucin-secreting cells and suggest that two compounds be further investigated for the possible use as mild expectorants during the treatment of inflammatory airway diseases.

• Biomolecules & Therapeutics
• /
• 제14권4호
• /
• pp.202-206
• /
• 2006

Angelicae Dahiricae Radix has been used for controlling inflammatory respiratory diseases in oriental medicine and their components, phellopterin, isoimperatorin and byakangelicol were reported to have various biological effects. In this study, we investigated whether phellopterin, isoimperatorin and byakangelicol affect adenosine triphosphate(ATP)-induced mucin secretion from cultured airway epithelial cells. Confluent primary hamster tracheal surface epithelial(HTSE) cells were metabolically radiolabeled using $^3H$-glucosamine for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on $^3H$-mucin secretion. The results were as follows: 1) phellopterin significantly inhibited ATP-induced mucin secretion; 2) However, isoimperatorin and byakangelicol did not affect ATP-induced mucin secretion, significantly. This result suggests that phellopterin can regulate 'mucin secretion induced by ATP'-a phenomenon simulating mucus overproduction from inflamed airway epithelial cells-by directly acting on airway mucin-secreting cells. Therefore, phellopterin should further be investigated for the possible use as mucoregulators in the treatment of inflammatory airway diseases.

• Biomolecules & Therapeutics
• /
• 제14권4호
• /
• pp.235-239
• /
• 2006

Angelicae Koreanae Radix has been used for controlling inflammatory respiratory diseases in folk medicine and their components, imperatorin, marmesinin and oxypeucedanin were reported to have diverse biological effects. In this study, we investigated whether imperatorin, marmesinin and oxypeucedanin affect adenosine triphosphate(ATP)-induced mucin secretion from cultured airway epithelial cells. Confluent primary hamster tracheal surface epithelial(HTSE) cells were metabolically radiolabeled using $^3H$-glucosamine for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on $^3H$-mucin secretion. The results were as follows: 1) imperatorin significantly inhibited ATP-induced mucin secretion; 2) However, marmesinin and oxypeucedanin did not affect ATP-induced mucin secretion, significantly. We conclude that imperatorin might inhibit ATP-induced mucin secretion by directly acting on airway mucin-secreting cells. Therefore, imperatorin should further be investigated for the possible use as mucoregulators in the treatment of inflammatory airway diseases.

• 대한금속재료학회지
• /
• 제48권11호
• /
• pp.995-1002
• /
• 2010

This study investigated the effect of process temperature on the alloying process during synthesis of $Sm_2Fe_{17}$ powder from ball-milled samarium oxide ($Sm_2O_3$) powders and a solid reducing agent of calcium hydrides ($CaH_2$) using iron nanopowder (n-Fe powder) by a reduction-diffusion (R-D) process. The $n-Fe-Sm_2O_3-CaH_2$ mixed powders were subjected to heat treatment at $850{\sim}1100^{\circ}C$ in $Ar-H_2$ for 5 h. It was found that the iron nanopowders in the mixed powders are sintered below $850^{\circ}C$ during the R-D process and the $SmH_2$ is synthesized by a reduced Sm that combines with $H_2$ around $850^{\circ}C$. The results showed that $SmH_2$ is able to separate Sm and $H_2$ respectively depending on an increase in process temperature, and the formed $Sm_2Fe_{17}$ phase on the surface of the sintered Fe nanopowder agglomerated at temperatures of $950{\sim}1100^{\circ}C$ in this study. The formation of the $Sm_2Fe_{17}$ layer is mainly due to the diffusion reaction of Sm atoms into the sintered Fe nanopowder, which agglomerates above $950^{\circ}C$. We concluded that nanoscale $Sm_2Fe_{17}$ powder can be synthesized by controlling the diffusion depth using well-dispersed Fe nanopowders.

• 한국추진공학회지
• /
• 제23권5호
• /
• pp.36-42
• /
• 2019

본 연구에서는 리오셀 섬유를 사용하여 탄소직물을 제조함에 있어, 인계 난연제인 Phosphoric Acid(PA)와 가교제인 Melamine resin (MR)을 사용하여 섬유의 전처리를 수행하고 TGA, FT-IR, XRD, 중량 분석을 통하여 물리적, 화학적 구조 변화에 대하여 고찰하였다. 전처리를 통하여 내염화 및 흑연화된 직물의 경우 미처리 직물과 비교하여 중량 수율이 14.7%, 직물 폭과 길이의 수율이 각각 15%, 15.5% 증가함을 확인하였다. 이러한 결과는 셀룰로오스의 탈수반응을 촉진과 함께 섬유 표면에 char를 형성하고, 셀룰로오스 분자 내의 가교반응을 유도하여 내염화 시 안정한 구조 형성에 의한 효과로 설명할 수 있다.