• Title/Summary/Keyword: ${\mu}$-approach

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Influence of air abrasion and different dentin sealing techniques on microtensile bond strength to dentin (상아질의 봉쇄 시기와 표면처리 방법이 미세인장 결합강도에 미치는 영향)

  • Kang, Dong-Ho;Han, Chong-Hyun;Park, Jung-Won;Kim, Sun-Jai
    • The Journal of Korean Academy of Prosthodontics
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    • v.48 no.1
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    • pp.8-15
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    • 2010
  • Purpose: The purpose of this study was to evaluate the effect of various methods of dentin bonding agent application and air abrasion pretreatment on microtensile bond strength between dentin and resin, using a self-etching adhesive system. Material and methods: Thirty freshly extracted human molars were obtained and divided into 6 groups of 5 teeth. A 2-step self etching adhesive system (Clearfil SE Bond) was used for all groups. The control specimens were prepared using a direct immediate bonding technique. The delayed dentin sealing specimens were prepared using an indirect approach without dentin prebonding. The immediate dentin sealing specimens were prepared using dentin prebonding immediately following preparation. Immediate dentin sealing teeth and delayed dentin sealing teeth had provisional restorations using Fermit for two weeks. Then all specimens of each group were divided into two groups of three, depending on air abrasion pretreatment. Composite "crowns" were incrementally built on and specimens were stored in water for 24 hours. All teeth were prepared for a microtensile bond strength test. Bond strength data were analyzed with a one-way ANOVA test, and post hoc comparison was done using the Scheffe's test. Results: The mean microtensile bond strengths of all groups were not statistically different from each other. Conclusion: When preparing teeth for indirect restorations, IDS and DDS with Clearfil SE bond, have no difference on the microtensile bond strength between dentin and resin. Air abrasion pretreatment did not affect the microtensile bond strength when using IDS and DDS with Clearfil SE bond.

Antioxidant Activity of Different Parts of Lespedeza bicolor and Isolation of Antioxidant Compound (싸리나무(Lespedeza bicolor) 부위별 추출물의 항산화 활성 및 항산화물질 분리)

  • Lee, Jae-Hak;Jhoo, Jin-Woo
    • Korean Journal of Food Science and Technology
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    • v.44 no.6
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    • pp.763-771
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    • 2012
  • In this study, total antioxidant properties of extracts from different parts of Lespedeza bicolor were determined using techniques of measuring 1,1-diphenyl-2-picryl hydrazyl/2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)-radical scavenging activity and total phenolic contents. The total antioxidant activities of leaf, stem and root extracts from various solvents (water, 50, 70, 100% ethanol, and hot-water) indicated that 50 and 70% ethanol extracts have high radical scavenging activities and phenolic contents. A systematic approach was used to determine the total antioxidant activity of different solvent fractions of the Lespedeza bicolor extracts, partitioning with chloroform, ethyl acetate, n-butanol, and water, and the ethyl acetate fraction was found to have the strongest antioxidant activity. Antioxidant assay-guided isolation was carried out to isolate potential antioxidant compounds. The ethyl acetate fraction of the leaf extract was subjected to silica gel, LH-20 and RP-18 column chromatography successively, and afforded compound 1, which was identified as eriodictyol by NMR and MS analysis, after which its antioxidant activity was determined.

An Archaeological Review of the Inscribed Bricks Excavated from the Tomb of Jang Mui: A Focus on the Collection of the National Museum of Korea (장무이묘 출토 명문전(銘文塼)의 고고학적 검토 -국립중앙박물관 소장품을 중심으로)

  • Lee Nakyung
    • Bangmulgwan gwa yeongu (The National Museum of Korea Journal)
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    • v.1
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    • pp.36-73
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    • 2024
  • The Tomb of Jang Mui located in Bongsan-gun, Hwanghae-do Province has attracted much attention since its first investigation due to the inscribed bricks found there that have allowed the guessing of the name and official title of its occupant and construction date. Inscriptions on these bricks, such as the "Prefect of Daebang Commandery Jang Mui" and the "Mu" (戊, the fifth sign of the Chinese calendar), and "Sin" (申, the ninth sign of the Chinese zodiac), have become the basis for believing the location of the government office of Daebang Commandery to be in Bongsangun, Hwanghae-do Province rather than somewhere in the Hangang River region. From the early days of its investigation, the tomb was suggested as historic remains of the Daebang Commandery along with the Earthen Fortress in Jitap-ri. Inscribed bricks excavated from the Tomb of Jang Mui were featured in several books and articles in the form of photographs and rubbings, leading to a vast body of studies on its construction period and the characteristics of its occupant that drew upon interpretations of the inscriptions. However, the inscribed bricks themselves were not publicly available outside those held in the collection of the University of Tokyo, making it difficult to expect consistent research findings on the types of inscribed bricks and their contents. Following previous studies re-examining the structure of the tomb and the materials used for its construction, most scholars dated the Tomb of Jang Mui to 348, a period after the collapse of Daebang Commandery. However, there is still a lack of adequate examination of the bricks, which account for the majority of the artifacts excavated from the tomb. Among the bricks excavated from most brick chamber tombs, including the Tomb of Jang Mui, only those with inscriptions or designs have been collected. Moreover, among these, only those with inscriptions or designs on the stretcher faces have been documented. Accordingly, the bricks themselves have been notably understudied. This paper intends to reorganize the contents of the inscriptions on eleven types (out of sixty-one pieces) of bricks in the collection of the National Museum of Korea, which make up the majority of the bricks excavated from the Tomb of Jang Mui. It also classified them according to their shapes. Furthermore, it examined the bricks from the Tomb of Jang Mui as architectural materials by focusing on their production techniques, including their forming, drying, and firing. Taking a more specific approach, it then compared the results to other bricks from the second century through the fourth century: those from the brick chamber tombs of the Nangnang and Daebang Commanderies and those from the brick chamber tombs built after Nangnang and Daebang Commanderies were ousted. The examination of bricks from the Tomb of Jang Mui has revealed that these bricks were basically produced using the brick manufacturing techniques of Nangnang, but they incorporated new elements found in bricks from brick chamber tombs or brick-and-stone chamber tombs constructed around the mid-fourth century in terms of their size, the use of lime, and the number of inscribed bricks. This supports the prevailing view that the date of the construction of the Tomb of Jang Mui is 348. The Tomb of Jang Mui sustained the existing brick chamber tomb burial tradition, but its ceiling was finished with stone. It demonstrates a blending of the brick chamber tomb practice of the Nangnang and Daebang Commanderies by using bricks produced based on related techniques, but with new elements such as the addition of a lime layer to the bricks. This fusion reflects the political circumstances of its time, such as the expulsion of the Daebang Commandery and the advance of the Goguryeo Kingdom, leading to diverse interpretations. Given archaeological evidence such as the structure, materials, and location of the tomb, the Tomb of Jang Mui appears to be highly related to the Goguryeo Kingdom. However, the forms of the inscribed bricks and the contents of the inscriptions share similarities with brick chamber tombs constructed during the third and fourth centuries in the Jiangsu and Zhejiang regions in China. Further studies on whether the use of lime was an influence from Goguryeo or a continuation of the Daebang tradition and a comparative examination with contemporaneous stone ceiling tombs will provide a more refined understanding of the Tomb of Jang Mui.