• Title/Summary/Keyword: adhesion

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Estimation of Interfacial Adhesion through the Micromechanical Analysis of Failure Mechanisms in DLC Film

  • Jeong, Jeung-Hyun;Park, Hae-Seok;Ahn, Jeong-Hoon;Dongil Kwon
    • The Korean Journal of Ceramics
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    • v.3 no.2
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    • pp.73-81
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    • 1997
  • In this paper, it is intended to present more reproducible and quantitative method for adhesion assemssement. In scratch test, micromechanical analysis on the stress state beneath the indenter was carried out considering the additional blister field. The interface adhesion was quantified as work of adhesion through Griffith energy approach on the basis of the analyzed stress state. The work of adhesion for DLC film/WC-Co substrate calculated through the proposed analysis shows the identical value regardless of distinctly different critical loads measured with the change of film thickness and scratching speed. On the other hand, uniaxial loading was imposed on DCL film/Al substrate, developing the transverse film cracks perpendicular to loading direction. Since this film cracking behavior depends on the relative magnitude of adhesion strength to film fracture strength, the quantification of adhesion strength was given a trial through the micromechanical analysis of adhesion-dependence of film cracking patterns. The interface shear strength can be quantified from the measurement of strain $\varepsilon$s and crack spacing $\lambda$ at the cessation of film cracking.

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Odontogenic Ameloblast-Associated Protein (Odam) Plays Crucial Roles in Osteoclast Differentiation via Control of Actin Ring Formation

  • Lee, Hye-Kyung;Park, Joo-Cheol
    • Journal of Korean Dental Science
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    • v.8 no.2
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    • pp.74-81
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    • 2015
  • Purpose: In osteoclast differentiation, actin-rich membrane protrusions play a crucial role in cell adhesion. Odontogenic ameloblast-associated protein (Odam) contributes to cell adhesion by inducing actin rearrangement. Odam-mediated RhoA activity may play a significant role in multinucleation of osteoclasts. However, the precise function of Odam in osteoclast cell adhesion and differentiation remains largely unknown. Here, we identify a critical role for Odam in inducing osteoclast adhesion and differentiation. Materials and Methods: The expression of Odam in osteoclasts was evaluated by immunohistochemistry. Primary mouse bone marrow and RAW264.7 cells were used to test the cell adhesion and actin ring formation induced by Odam. Result: Odam was expressed in osteoclasts around alveolar bone. Odam transfection induced actin filament rearrangement and cell adhesion compared with the control or collagen groups. Overexpression of Odam promoted actin stress fiber remodeling and cell adhesion, resulting in increased osteoclast fusion. Conclusion: These results suggest that Odam expression in primary mouse osteoclasts and RAW264.7 cells promotes their adhesion, resulting in the induction of osteoclast differentiation.

Adhesion and Friction Forces of Micro Surface Bumps (마이크로 표면돌기의 응착력과 마찰력)

  • Cho Sung-San;Lim Je-Sung;Park Seungho;Lee Seungseop
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.8 s.227
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    • pp.1087-1092
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    • 2004
  • Adhesion and friction forces influence adversely on performance and durability of MEMS. It has been reported that the adhesion and friction forces can be reduced with the introduction of micro surface bumps into the contacting interfaces. In this study experiments were conducted to investigate comparatively the effect of hemispherical and torus micro bumps on the adhesion and friction forces. It is confirmed that micro bumps reduce the adhesion and friction forces, and their effect is more pronounced with the bumps of smaller outer boundary radius. Moreover, the results shows that the torus bumps exhibit more rapid decrease of the adhesion and friction forces with the decrease in the outer boundary radius of bump than the hemispherical bumps. When the magnitude of adhesion force is same, the torus bumps generate smaller friction force than the hemispherical bumps. The usage of hemispherical and torus bumps to reduce the adhesion and friction forces in MEMS is discussed.

Estimation Study on the Wheel/Rail Adhesion Coefficient of Railway Vehicles Using the Scaled Adhesion Tester (축소 점착시험기를 이용한 휠/레일의 점착계수 추정에 관한 연구)

  • Kim, Min Soo;Hee Kim, Kyung;Kwon, Seok Jin
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.7
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    • pp.603-609
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    • 2015
  • Railway vehicles driven by wheels obtain force required for propulsion and braking by adhesive force between wheels and rails, this adhesive force is determined by multiplying adhesion coefficient of the friction surface by the applied axle load. Because the adhesion coefficient has a peak at certain slip velocity, it is important to determine the maximum values of the friction coefficient on the contact area. But this adhesive phenomenon is not clearly examined or analyzed. Thus we have developed new test procedure using the scaled adhesion test-bench for analyzing of the adhesion coefficient between wheel and rail. This adhesion test equipment is an experimental device that contacts mutually with twin disc which are equivalent to wheels and rails of railway vehicles.

Sodium Carboxymethylcellulose and Hyaluronic Acid on Prevention of Intra-abdominal Adhesion in Rats (Rat에서 Sodium Carboxymethylcellulose와 Hyaluronic acid의 복강 내 유착 예방)

  • 한태성;이주명;윤영민;강태영;신태균;강윤호;김남중;김희석;이경갑
    • Journal of Veterinary Clinics
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    • v.20 no.3
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    • pp.323-327
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    • 2003
  • This study has been conducted to compare the efficacy of sodium carboxymethylcellulose (SCMC) and hyaluronic acid (HA) on prevention of adhesion after artificial wound was induced in intestine. 1 % SCMC and 0.3% HA solution and saline solution were respectively administered to abdominal cavity. Each of the three groups consists of 11 rats. The abdominal cavity of each rat was coated with 2 ml of the allocated solution just after the abdomen was cut open, and it was coated with each solution of 1 ml before abrasion were caused on the cecum, the ascending colon and the transverse colon. Then, an additional 1 ml solution was injected before the abdomen was closed. On day 14 after the operation, each adhesion formation was evaluated at the score of 0-4. The HA group and SCMC group showed significantly lower adhesion scores than control group in all regions(P< 0.05). The adhesion scores of ascending colon, transverse colon and no abrasion region of the viscera showed little difference between HA group and SCMC group(P< 0.05), but the effect of adhesion reduction showed higher tendency in the HA group than the SCMC. The adhesion score of the cecum was significantly lower in HA group than SCMC group(P< 0.05). In conclusion, the SCMC solution and HA solution were effective on prevention of abdominal adhesion resulting from the celiotomy. Among of them, the HA solution could be more effective on prevention of adhesion than SCMC solution.

Adhesion between Rubber Compound and Copper-Film-Coated Steel Plate Prepared by Vacuum Sputtering and Substitution Plating Methods (진공증착법과 치환도금법으로 제조한 구리박막 피복철판과 배합고무의 접착)

  • Moon, Kyung-Ho;Han, Min-Hyun;Seo, Gon
    • Journal of Adhesion and Interface
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    • v.4 no.3
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    • pp.1-8
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    • 2003
  • Adhesion between rubber compound and copper-film-coated steel plate (abbreviated hereafter as copper film plate) with different thicknesses of copper film was investigated. Two different methods were employed for the preparation of the copper film plates: a substitution plating of preelectroplated zinc with copper ion and a vacuum sputtering of copper on steel plate. Adhesion strength of the copper film plates with rubber compounds was largely dependent upon the thickness of copper film, regardless of their preparation methods. The copper film plates with thinner thickness than 75 nm showed high adhesion comparable to brass, while those with thicker copper film showed poor adhesion due to excessive growth of copper sulfide at adhesion interface.

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Adhesion Performance and Curing Behaviors of Acid-free Acrylic PSAs Using Two Types of Curing Agents (Acid-free 아크릴계 점착제의 접착 물성 및 경화거동 연구)

  • Lee, Seung-Woo;Park, Ji-Won;Kwon, Young-Eun;Kim, Hyun-Joong
    • Journal of Adhesion and Interface
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    • v.12 no.2
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    • pp.67-72
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    • 2011
  • Acrylic pressure-sensitive adhesives are used in many different parts in the world. But acrylic acid in PSAs may occur unexpected results such as corroding adherends or producing by-products when applied within electronic devices. This study employed acrylic PSAs based on 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl acrylate (2-HEA) and butyl acrylate (BA) with different coating thickness. There are two types of curing agents. One is methylaziridine derivative (MAZ) and the other is aluminum acetylacetonate (AlACA). This study examined the adhesion performance and curing behaviors using peel strength, probe tack and gel fraction. Also, the viscoelastic properties of acrylic PSAs were investigated from Advanced rheometric expansion system (ARES).

Hardness and adhesion of the reactively sputtered Zr-ZrN on the stainless steel(SUS304) and tool steel(SKH9) (스테인레스와 공구강 위에 스퍼터링된 Zr-ZrN 코팅층의 경도 및 밀착성에 대한 연구)

  • 예길촌;신현준;권식철;백원승
    • Journal of the Korean institute of surface engineering
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    • v.26 no.6
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    • pp.316-326
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    • 1993
  • Adhesion and hardeness are the most important properties of a hard coated layer which is applied to wear-resistant devices. Zr/ZrN layer was deposited on tool steel(SKH9) and stainless steel(SUS304) by a re-active D.C. magnetron sputtering technique and their microhardness and adhesion strength were measured for the films processed by changing the partial pressures of $N_2$ gas (4~10$\times$$10^{-4}$mbar) and the substrate bias voltage(0~250V). The adhesion strength was evaluated by acoustic signals through the scratch-test with the incremental applied load. As the partial pressure of $N_2$ gas and the substrate bias voltage were increased, the adhesion strength of tool steel was observed to be stronger than that of the stainless steel. The adhesion strength was generally, observed to decrease with the same tendency regardless of the kinds of substrates. The adhesion strength of tool steel was increased more and more strongly than that of stainless steel as heat-treated temperature was increased. The strength of tool steel was appeared to be high adhesion strength at $400^{\circ}C$. From the failure mode of the film during the scratch adhesion test, the cohesive failure was observed to be obvious and the adhesive failure in a minor portion in the Zr/ZrN doublelayer regardless of the kinds of substrates.

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Curing Behavior and Adhesion Performance of Urea-Melamine-Formaldehyde (UMF) Resin by Staged Addition of Melamine (멜라민 첨가 순서에 따른 UMF 접착제의 경화거동과 접착력의 영향)

  • Xu, Guang-Zhu;Eom, Young-Geun;Lee, Young-Kyu;Lim, Dong-Hyuk;Lee, Byoung-Ho;Kim, Hyun-Joong
    • Journal of Adhesion and Interface
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    • v.10 no.2
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    • pp.84-89
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    • 2009
  • The objective of this research was to investigate the curing behavior and adhesion performance of urea-melamine-formaldehyde (UMF) resin for the four types of UMF-1, UMF-2, UMF-3, and UMF-4 which synthesized by the staged addition of melamine. Also, various network structures of these resin types were discussed based on their different curing behavior and adhesion performance. The curing behavior was evaluated by DMTA and thermal stability was checked by TGA. Adhesion performance was evaluated by dry and wet shear strengths and the pH value of each cured resin was checked to see its effect on the adhesion performance. The results indicated that the UMF-1 resin type by the addition of melamine initially with the urea and formaldehyde at the same F/(U+M) rate showed the lowest thermal stability, rigidity (${\Delta}E^{\prime}$), temperature of tan ${\delta}$ maximum ($T_{tan}\;_{\delta}$), and wet shear strength, and pH value of cured resin. In wet shear strength, however, the UMF-4 resin type appears to be slightly higher than UMF-1 resin type.

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Effect of Tea Polyphenols on the Adhesion of Highly Metastatic Human Lung Carcinoma Cell Lines to Endothelial Cells in Vitro

  • Zheng, Feng-Jin;Shi, Lin;Yang, Jun;Deng, Xiao-Hui;Wu, Yu-Quan;Yan, Xi-Qing;Huang, Ning
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.8
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    • pp.3751-3755
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    • 2012
  • Aim: Tea polyphenols are known to play roles in critical steps of human lung carcinoma cell metastasis. For understanding the mechanisms whereby they inhibit tumor metastasis, the present study was conducted to investigate their effects on the adhesion of highly metastatic lung carcinoma cell lines (PG cells) to endothelial cells (EC cells) and adhesion molecule expression in vitro. Methods: The expression of CD44 or CD54 in the PG cells was detected by flow cytometry and adhesion of PG cells to EC cells was assessed by confocal microscopy double fluorescence staining. Results: The results showed that tea polyphenols: (1) inhibited the expression of CD44 and CD54, two important adhesion molecules in the PG cells in a dose-dependent manner; (2) significantly blocked the adhesion of PG cells to EC cells not only in a state of rest but also when active; and (3) influenced CD44 and CD54 expression during the adhesion process of PG cells to EC cells. Conclusions: The data indicated that the blocking role of tea polyphenols in the adhesion of PG cells to EC cells is related to CD44 and CD54. The mechanism of tea polyphenol prevention of human lung carcinoma metastasis might be through inhibiting adhesion molecule expression to block cancer cell adhesion.