Science.gov

Sample records for adhesion molecule-3-grabbing non-integrin

  1. HIV-1 gp120 Glycoprotein Interacting with Dendritic Cell-specific Intercellular Adhesion Molecule 3-grabbing Non-integrin (DC-SIGN) Down-Regulates Tight Junction Proteins to Disrupt the Blood Retinal Barrier and Increase Its Permeability.

    PubMed

    Qian, Yi-Wen; Li, Chuan; Jiang, Ai-Ping; Ge, Shengfang; Gu, Ping; Fan, Xianqun; Li, Tai-Sheng; Jin, Xia; Wang, Jian-Hua; Wang, Zhi-Liang

    2016-10-28

    Approximately 70% of HIV-1 infected patients acquire ocular opportunistic infections and manifest eye disorders during the course of their illness. The mechanisms by which pathogens invade the ocular site, however, are unclear. Under normal circumstances, vascular endothelium and retinal pigment epithelium (RPE), which possess a well developed tight junction complex, form the blood-retinal barrier (BRB) to prevent pathogen invasion. We hypothesize that disruption of the BRB allows pathogen entry into ocular sites. The hypothesis was tested using in vitro models. We discovered that human RPE cells could bind to either HIV-1 gp120 glycoproteins or HIV-1 viral particles. Furthermore, the binding was mediated by dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN) expressed on RPE cells. Upon gp120 binding to DC-SIGN, cellular NF-κB signaling was triggered, leading to the induction of matrix metalloproteinases, which subsequently degraded tight junction proteins and disrupted the BRB integrity. DC-SIGN knockdown or prior blocking with a specific antibody abolished gp120-induced matrix metalloproteinase expression and reduced the degradation of tight junction proteins. This study elucidates a novel mechanism by which HIV, type 1 invades ocular tissues and provides additional insights into the translocation or invasion process of ocular complication-associated pathogens.

  2. Analysis of genetic polymorphisms in CCR5, CCR2, stromal cell-derived factor-1, RANTES, and dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin in seronegative individuals repeatedly exposed to HIV-1.

    PubMed

    Liu, Huanliang; Hwangbo, Yon; Holte, Sarah; Lee, Jean; Wang, Chunhui; Kaupp, Nicole; Zhu, Haiying; Celum, Connie; Corey, Lawrence; McElrath, M Juliana; Zhu, Tuofu

    2004-09-15

    To determine the influence of host genetics on human immunodeficiency virus (HIV) type 1 infection, we examined 94 repeatedly exposed seronegative (ES) individuals for polymorphisms in multiple genes and compared the results with those for 316 HIV-1-seropositive and 425 HIV-1-seronegative individuals. The frequency of homozygous C-C chemokine receptor (CCR) 5- Delta 32 was higher in ES (3.2%) than in HIV-1-seropositive individuals (0.0%; P=.012). However, the CCR5-59029A, CCR2-64I, stromal cell-derived factor (SDF)-1-3'A, RANTES (regulated on activation, normally T cell-expressed and -secreted)-403A, and RANTES-28G polymorphisms were not associated with resistance to HIV-1 infection. Furthermore, we identified novel variants in the DC-SIGN (dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin) repeat region and observed that heterozygous DC-SIGN reduced the risk of HIV-1 infection (3.2% in ES individuals vs. 0.0% in HIV-1-seropositive individuals; P=.011).

  3. Adhesions

    MedlinePlus

    Adhesions are bands of scar-like tissue. Normally, internal tissues and organs have slippery surfaces so they can shift easily as the body moves. Adhesions cause tissues and organs to stick together. They ...

  4. Adhesion

    MedlinePlus

    ... the intestines, adhesions can cause partial or complete bowel obstruction . Adhesions inside the uterine cavity, called Asherman syndrome , ... 1. Read More Appendicitis Asherman syndrome Glaucoma Infertility Intestinal obstruction Review Date 4/5/2016 Updated by: Irina ...

  5. The physiological role of DC-SIGN: a tale of mice and men.

    PubMed

    Garcia-Vallejo, Juan J; van Kooyk, Yvette

    2013-10-01

    The innate immune receptor DC-SIGN (dendritic cell-specific intercellular adhesion molecule-3 grabbing non-integrin) was discovered over a decade ago and was initially identified as a pattern recognition receptor. In addition to its ability to recognize a broad range of pathogen-derived ligands and self-glycoproteins, DC-SIGN also mediates intercellular adhesion, as well as antigen uptake and signaling, which is a functional hallmark of dendritic cells (DCs). Most research on DC-SIGN has relied on in vitro studies. The in vivo function of DC-SIGN is difficult to address, in part because there are eight genetic homologs in mice with no clear DC-SIGN ortholog. Here, we summarize the functions attributed to DC-SIGN based on in vitro data and discuss the limitations of available mouse models to uncover the physiological role of this receptor in vivo.

  6. Epitope mapping on the dendritic cell-specific ICAM-3-grabbing non-integrin (DC-SIGN) pathogen-attachment factor.

    PubMed

    Sierra-Filardi, Elena; Estecha, Ana; Samaniego, Rafael; Fernández-Ruiz, Elena; Colmenares, María; Sánchez-Mateos, Paloma; Steinman, Ralph M; Granelli-Piperno, Angela; Corbí, Angel L

    2010-01-01

    DC-SIGN (dendritic cell-specific ICAM-3-grabbing non-integrin) is a myeloid pathogen-attachment factor C-type lectin which recognizes mannose- and fucose-containing oligosaccharide ligands on clinically relevant pathogens. Intracellular signaling initiated upon ligand engagement of DC-SIGN interferes with TLR-initiated signals, and modulates the T cell activating and polarizing ability of antigen-presenting cells. The C-terminal carbohydrate-recognition domain (CRD) of DC-SIGN is preceded by a neck domain composed of eight 23-residue repeats which mediate molecule multimerization, and whose polymorphism correlates with altered susceptibility to SARS and HIV infection. Naturally occurring isoforms and chimaeric molecules, in combination with established recognition properties, were used to define seven structural and functional epitopes on DC-SIGN. Three epitopes mapped to the CRD, one of which is multimerization-dependent and only exposed on DC-SIGN monomers. Epitopes within the neck domain were conformation-independent and unaltered upon molecule multimerization, but were differentially affected by neck domain truncations. Although neck-specific antibodies exhibited lower function-blocking ability, they were more efficient at inducing molecule internalization. Moreover, crosslinking of the different epitopes resulted in distinct levels of microclustering on the cell surface. The identification of independent epitopes on the DC-SIGN molecule might facilitate the design of reagents that modulate the T cell activating and polarizing ability of DC-SIGN-expressing cells without preventing its antigen- and pathogen-recognition capacities.

  7. The interaction between uPAR and vitronectin triggers ligand-independent adhesion signalling by integrins

    PubMed Central

    Ferraris, Gian Maria Sarra; Schulte, Carsten; Buttiglione, Valentina; De Lorenzi, Valentina; Piontini, Andrea; Galluzzi, Massimiliano; Podestà, Alessandro; Madsen, Chris D; Sidenius, Nicolai

    2014-01-01

    The urokinase-type plasminogen activator receptor (uPAR) is a non-integrin vitronectin (VN) cell adhesion receptor linked to the plasma membrane by a glycolipid anchor. Through structure–function analyses of uPAR, VN and integrins, we document that uPAR-mediated cell adhesion to VN triggers a novel type of integrin signalling that is independent of integrin–matrix engagement. The signalling is fully active on VN mutants deficient in integrin binding site and is also efficiently transduced by integrins deficient in ligand binding. Although integrin ligation is dispensable, signalling is crucially dependent upon an active conformation of the integrin and its association with intracellular adaptors such as talin. This non-canonical integrin signalling is not restricted to uPAR as it poses no structural constraints to the receptor mediating cell attachment. In contrast to canonical integrin signalling, where integrins form direct mechanical links between the ECM and the cytoskeleton, the molecular mechanism enabling the crosstalk between non-integrin adhesion receptors and integrins is dependent upon membrane tension. This suggests that for this type of signalling, the membrane represents a critical component of the molecular clutch. PMID:25168639

  8. Biocompatible Adhesives

    DTIC Science & Technology

    1991-03-01

    pressure sensitive elastomer, polyisobutylene. with water soluble adhesives such as carboxy methyl ceiiulose, pectin and gelatin for adhesion to... cellulose and nylon films, were most often used in 180 peel adhesion tests on the adhesives. Films were cast on one substrate and the other was moistened...irritation. 4. Peel adhesion to hydrated cellulose , nylon and cotton cloth substrates was satisfactory. So too was the peel adhesion as a function of

  9. Monovalent mannose-based DC-SIGN antagonists: targeting the hydrophobic groove of the receptor.

    PubMed

    Tomašić, Tihomir; Hajšek, David; Švajger, Urban; Luzar, Jernej; Obermajer, Nataša; Petit-Haertlein, Isabelle; Fieschi, Franck; Anderluh, Marko

    2014-03-21

    Dendritic cell-specific, intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) is a C-type lectin expressed specifically on dendritic cells. It is a primary site for recognition and binding of various pathogens and thus a promising therapeutic target for inhibition of pathogen entry and subsequent prevention of immune defense cell infection. We report the design and synthesis of d-mannose-based DC-SIGN antagonists bearing diaryl substituted 1,3-diaminopropanol or glycerol moieties incorporated to target the hydrophobic groove of the receptor. The designed glycomimetics were evaluated by in vitro assay of the isolated DC-SIGN extracellular domain for their ability to compete with HIV-1 gp120 for binding to the DC-SIGN carbohydrate recognition domain. Compounds 14d and 14e, that display IC50 values of 40 μM and 50 μM, are among the most potent monovalent DC-SIGN antagonists reported. The antagonistic effect of all the synthesized compounds was further evaluated by a one-point in vitro assay that measures DC adhesion. Compounds 14d, 14e, 18d and 18e were shown to act as functional antagonists of DC-SIGN-mediated DC adhesion. The binding mode of 14d was also studied by molecular docking and molecular dynamics simulation, which revealed flexibility of 14d in the binding site and provides a basis for further optimization.

  10. Intrauterine Adhesions

    MedlinePlus

    ... adhesion formation are infections of the uterine lining (endometritis), removal of fibroids in the cavity of the ... to prevent adhesions from reforming. Hormonal treatment with estrogen and NSAIDs are frequently prescribed after surgery to ...

  11. S-layer proteins from Lactobacillus sp. inhibit bacterial infection by blockage of DC-SIGN cell receptor.

    PubMed

    Prado Acosta, Mariano; Ruzal, Sandra M; Cordo, Sandra M

    2016-11-01

    Many species of Lactobacillus sp. possess Surface(s) layer proteins in their envelope. Among other important characteristics S-layer from Lactobacillus acidophilus binds to the cellular receptor DC-SIGN (Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin; CD209), which is involved in adhesion and infection of several families of bacteria. In this report we investigate the activity of new S-layer proteins from the Lactobacillus family (Lactobacillus acidophilus, Lactobacillus brevis, Lactobacillus helveticus and Lactobacillus kefiri) over the infection of representative microorganisms important to human health. After the treatment of DC-SIGN expressing cells with these proteins, we were able to diminish bacterial infection by up to 79% in both gram negative and mycobacterial models. We discovered that pre-treatment of the bacteria with S-layers from Lactobacillus acidophilus and Lactobacillus brevis reduced bacteria viability but also prevent infection by the pathogenic bacteria. We also proved the importance of the glycosylation of the S-layer from Lactobacillus kefiri in the binding to the receptor and thus inhibition of infection. This novel characteristic of the S-layers proteins may contribute to the already reported pathogen exclusion activity for these Lactobacillus probiotic strains; and might be also considered as a novel enzymatic antimicrobial agents to inhibit bacterial infection and entry to host cells.

  12. Distribution of dendritic cells expressing dendritic cell-specific ICAM-3-grabbing non-integrin (DC-SIGN, CD209): Morphological analysis using a novel Photoshop-aided multiple immunohistochemistry technique.

    PubMed

    Masuda, Akihiro; Nishikawa, Toshio

    2014-08-01

    The distribution of dendritic cells (DCs) expressing DC-specific ICAM-3-grabbing non-integrin (DC-SIGN, CD209) and the morphological interaction of DC-SIGN⁺ DCs with other cells, especially B cells, in tonsillar and other lymphoid tissues were investigated by multiple immunohistochemistry (IHC) using the graphics editing program Photoshop, which enabled staining with 4 or more antibodies in formalin-fixed paraffin sections. Images obtained by repetition of conventional IHC using diaminobenzidine color development in a tissue section were processed on Photoshop for multiple staining. DC-SIGN⁺ DCs were present in the area around the lymphoid follicles and formed a DC-SIGN⁺ DC-rich area, and these cells contacted not only T cells, fascin⁺ DCs, and blood vessels but also several subsets of B cells simultaneously, including naïve and memory B cells. DC-SIGN⁺ DCs may play an important role in the regulation of the immune response mediated by not only T cells but also B cells. The multiple IHC method introduced in the present study is a simple and useful method for analyzing details of complex structures. Because this method can be applied to routinely processed paraffin sections with conventional IHC with diaminobenzidine, it can be applied to a wide variety of archival specimens.

  13. Abdominal Adhesions

    MedlinePlus

    ... Adhesions 1 Ward BC, Panitch A. Abdominal adhesions: current and novel therapies. Journal of Surgical Research. 2011;165(1):91–111. Seek Help for ... and how to participate, visit the NIH Clinical Research Trials and You website ... Foundation for Functional Gastrointestinal Disorders 700 West Virginia ...

  14. Beyond attachment: Roles of DC-SIGN in dengue virus infection.

    PubMed

    Liu, Ping; Ridilla, Marc; Patel, Pratik; Betts, Laurie; Gallichotte, Emily; Shahidi, Lidea; Thompson, Nancy L; Jacobson, Ken

    2017-04-01

    Dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN), a C-type lectin expressed on the plasma membrane by human immature dendritic cells, is a receptor for numerous viruses including Ebola, SARS and dengue. A controversial question has been whether DC-SIGN functions as a complete receptor for both binding and internalization of dengue virus (DENV) or whether it is solely a cell surface attachment factor, requiring either hand-off to another receptor or a co-receptor for internalization. To examine this question, we used 4 cell types: human immature dendritic cells and NIH3T3 cells expressing either wild-type DC-SIGN or 2 internalization-deficient DC-SIGN mutants, in which either the 3 cytoplasmic internalization motifs are silenced by alanine substitutions or the cytoplasmic region is truncated. Using confocal and super-resolution imaging and high content single particle tracking, we investigated DENV binding, DC-SIGN surface transport, endocytosis, as well as cell infectivity. DC-SIGN was found colocalized with DENV inside cells suggesting hand-off at the plasma membrane to another receptor did not occur. Moreover, all 3 DC-SIGN molecules on NIH3T3 cells supported cell infection. These results imply the involvement of a co-receptor because cells expressing the internalization-deficient mutants could still be infected.

  15. Reactive oxygen species production by human dendritic cells involves TLR2 and dectin-1 and is essential for efficient immune response against Mycobacteria.

    PubMed

    Romero, María Mercedes; Basile, Juan Ignacio; Corra Feo, Laura; López, Beatriz; Ritacco, Viviana; Alemán, Mercedes

    2016-06-01

    Tuberculosis remains the single largest infectious disease with 10 million new cases and two million deaths that are estimated to occur yearly, more than any time in history. The intracellular replication of Mycobacterium tuberculosis (Mtb) and its spread from the lungs to other sites occur before the development of adaptive immune responses. Dendritic cells (DC) are professional antigen-presenting cells whose maturation is critical for the onset of the protective immune response against tuberculosis disease and may vary depending on the nature of the cell wall of Mtb strain. Here, we describe the role of the endogenous production of reactive oxygen species (ROS) on DC maturation and expansion of Mtb-specific lymphocytes. Here, we show that Mtb induces DC maturation through TLR2/dectin-1 by generating of ROS and through Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN) in a ROS independently manner. Based on the differences observed in the ability to induce DC maturation, ROS production and lymphocyte proliferation by those Mtb families widespread in South America, i.e., Haarlem and Latin American Mediterranean and the reference strain H37Rv, we propose that variance in ROS production might contribute to immune evasion affecting DC maturation and antigen presentation.

  16. Adhesive plasters

    DOEpatents

    Holcombe, Jr., Cressie E.; Swain, Ronald L.; Banker, John G.; Edwards, Charlene C.

    1978-01-01

    Adhesive plaster compositions are provided by treating particles of Y.sub.2 O.sub.3, Eu.sub.2 O.sub.3, Gd.sub.2 O.sub.3 or Nd.sub.2 O.sub.3 with dilute acid solutions. The resulting compositions have been found to spontaneously harden into rigid reticulated masses resembling plaster of Paris. Upon heating, the hardened material is decomposed into the oxide, yet retains the reticulated rigid structure.

  17. Adhesion and Cohesion

    PubMed Central

    von Fraunhofer, J. Anthony

    2012-01-01

    The phenomena of adhesion and cohesion are reviewed and discussed with particular reference to dentistry. This review considers the forces involved in cohesion and adhesion together with the mechanisms of adhesion and the underlying molecular processes involved in bonding of dissimilar materials. The forces involved in surface tension, surface wetting, chemical adhesion, dispersive adhesion, diffusive adhesion, and mechanical adhesion are reviewed in detail and examples relevant to adhesive dentistry and bonding are given. Substrate surface chemistry and its influence on adhesion, together with the properties of adhesive materials, are evaluated. The underlying mechanisms involved in adhesion failure are covered. The relevance of the adhesion zone and its importance with regard to adhesive dentistry and bonding to enamel and dentin is discussed. PMID:22505913

  18. Lactobacillus reuteri Surface Mucus Adhesins Upregulate Inflammatory Responses Through Interactions With Innate C-Type Lectin Receptors

    PubMed Central

    Bene, Krisztián P.; Kavanaugh, Devon W.; Leclaire, Charlotte; Gunning, Allan P.; MacKenzie, Donald A.; Wittmann, Alexandra; Young, Ian D.; Kawasaki, Norihito; Rajnavolgyi, Eva; Juge, Nathalie

    2017-01-01

    The vertebrate gut symbiont Lactobacillus reuteri exhibits strain-specific adhesion and health-promoting properties. Here, we investigated the role of the mucus adhesins, CmbA and MUB, upon interaction of L. reuteri ATCC PTA 6475 and ATCC 53608 strains with human monocyte-derived dendritic cells (moDCs). We showed that mucus adhesins increased the capacity of L. reuteri strains to interact with moDCs and promoted phagocytosis. Our data also indicated that mucus adhesins mediate anti- and pro-inflammatory effects by the induction of interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-α), IL-1β, IL-6, and IL-12 cytokines. L. reuteri ATCC PTA 6475 and ATCC 53608 were exclusively able to induce moDC-mediated Th1 and Th17 immune responses. We further showed that purified MUB activates moDCs and induces Th1 polarized immune responses associated with increased IFNγ production. MUB appeared to mediate these effects via binding to C-type lectin receptors (CLRs), as shown using cell reporter assays. Blocking moDCs with antibodies against DC-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN) or Dectin-2 did not affect the uptake of the MUB-expressing strain, but reduced the production of TNF-α and IL-6 by moDCs significantly, in line with the Th1 polarizing capacity of moDCs. The direct interaction between MUB and CLRs was further confirmed by atomic force spectroscopy. Taken together these data suggest that mucus adhesins expressed at the cell surface of L. reuteri strains may exert immunoregulatory effects in the gut through modulating the Th1-promoting capacity of DCs upon interaction with C-type lectins. PMID:28326063

  19. DC-SIGN expression on podocytes and its role in inflammatory immune response of lupus nephritis.

    PubMed

    Cai, Minchao; Zhou, Tong; Wang, Xuan; Shang, Minghua; Zhang, Yueyue; Luo, Maocai; Xu, Chundi; Yuan, Weijie

    2016-03-01

    Podocytes, the main target of immune complex, participate actively in the development of glomerular injury as immune cells. Dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) is an innate immune molecular that has an immune recognition function, and is involved in mediation of cell adhesion and immunoregulation. Here we explored the expression of DC-SIGN on podocytes and its role in immune and inflammatory responses in lupus nephritis (LN). Expression of DC-SIGN and immunoglobulin (Ig)G1 was observed in glomeruli of LN patients. DC-SIGN was co-expressed with nephrin on podocytes. Accompanied by increased proteinuria of LN mice, DC-SIGN and IgG1 expressions were observed in the glomeruli from 20 weeks, and the renal function deteriorated up to 24 weeks. Mice with anti-DC-SIGN antibody showed reduced proteinuria and remission of renal function. After the podocytes were stimulated by serum of LN mice in vitro, the expression of DC-SIGN, major histocompatibility complex (MHC) class II and CD80 was up-regulated, stimulation of T cell proliferation was enhanced and the interferon (IFN)-γ/interleukin (IL)-4 ratio increased. However, anti-DC-SIGN antibody treatment reversed these events. These results suggested that podocytes in LN can exert DC-like function through their expression of DC-SIGN, which may be involved in immune and inflammatory responses of renal tissues. However, blockage of DC-SIGN can inhibit immune functions of podocytes, which may have preventive and therapeutic effects.

  20. Thermal Characterization of Adhesive

    NASA Technical Reports Server (NTRS)

    Spomer, Ken A.

    1999-01-01

    The current Space Shuttle Reusable Solid Rocket Motor (RSRM) nozzle adhesive bond system is being replaced due to obsolescence. Down-selection and performance testing of the structural adhesives resulted in the selection of two candidate replacement adhesives, Resin Technology Group's Tiga 321 and 3M's EC2615XLW. This paper describes rocket motor testing of these two adhesives. Four forty-pound charge motors were fabricated in configurations that would allow side by side comparison testing of the candidate replacement adhesives and the current RSRM adhesives. The motors provided an environment where the thermal performance of adhesives in flame surface bondlines was compared. Results of the FPC testing show that: 1) The phenolic char depths on radial bond lines is approximately the same and vary depending on the position in the blast tube regardless of which adhesive was used; 2) The adhesive char depth of the candidate replacement adhesives is less than the char depth of the current adhesives; 3) The heat-affected depth of the candidate replacement adhesives is less than the heat-affected depth of the current adhesives; and 4) The ablation rates for both replacement adhesives are slower than that of the current adhesives.

  1. Understanding Marine Mussel Adhesion

    SciTech Connect

    H. G. Silverman; F. F. Roberto

    2007-12-01

    In addition to identifying the proteins that have a role in underwater adhesion by marine mussels, research efforts have focused on identifying the genes responsible for the adhesive proteins, environmental factors that may influence protein production, and strategies for producing natural adhesives similar to the native mussel adhesive proteins. The production-scale availability of recombinant mussel adhesive proteins will enable researchers to formulate adhesives that are waterimpervious and ecologically safe and can bind materials ranging from glass, plastics, metals, and wood to materials, such as bone or teeth, biological organisms, and other chemicals or molecules. Unfortunately, as of yet scientists have been unable to duplicate the processes that marine mussels use to create adhesive structures. This study provides a background on adhesive proteins identified in the blue mussel, Mytilus edulis, and introduces our research interests and discusses the future for continued research related to mussel adhesion.

  2. Understanding Marine Mussel Adhesion

    PubMed Central

    Roberto, Francisco F.

    2007-01-01

    In addition to identifying the proteins that have a role in underwater adhesion by marine mussels, research efforts have focused on identifying the genes responsible for the adhesive proteins, environmental factors that may influence protein production, and strategies for producing natural adhesives similar to the native mussel adhesive proteins. The production-scale availability of recombinant mussel adhesive proteins will enable researchers to formulate adhesives that are water-impervious and ecologically safe and can bind materials ranging from glass, plastics, metals, and wood to materials, such as bone or teeth, biological organisms, and other chemicals or molecules. Unfortunately, as of yet scientists have been unable to duplicate the processes that marine mussels use to create adhesive structures. This study provides a background on adhesive proteins identified in the blue mussel, Mytilus edulis, and introduces our research interests and discusses the future for continued research related to mussel adhesion. PMID:17990038

  3. Development and evaluation of a double antibody sandwich ELISA for the detection of human sDC-SIGN.

    PubMed

    Chen, Shang-Liang; Li, Yan-Li; Tang, Yuan; Chen, Zhi-Cheng; Zhou, Jing; Zhou, Jia; Lu, Xiao; Zhao, Na; Chen, Zheng-Liang; Zuo, Daming

    2016-09-01

    sDC-SIGN is the soluble form of dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN, CD209), which is a molecule involved with pathogen recognition and immune regulation. However, there is no commercially available ELISA kit for detecting human sDC-SIGN, and the normal range of this molecule is unknown. Here, we describe an ELISA for detecting human sDC-SIGN with high specificity. First, sDC-SIGN protein was expressed and purified. Monoclonal and polyclonal antibodies were then raised against the purified protein and subsequently characterized. A sandwich ELISA was developed using polyclonal antibodies specific for sDC-SIGN for capture and a biotin-labeled monoclonal antibody specific for sDC-SIGN for detection of protein. This method has sensitivity up to 0.2 ng/ml. Using this ELISA, we found that the concentration of sDC-SIGN in sera of healthy volunteers ranges from 0-319 ng/ml with a mean concentration of 27.14 ng/ml. Interestingly, the concentration of sDC-SIGN in sera from patients with cancer or chronic hepatitis B virus (CHB) infection was lower than that of health controls. The mean concentrations of sDC-SIGN in cancer patients and chronic hepatitis B virus infection patients were 3.2 ng/ml and 3.8 ng/ml, respectively. We developed a sandwich ELISA for detecting human sDC-SIGN and demonstrated its use by assessing sera concentrations of sDC-SIGN in patients with cancer and chronic CHB infection compared to that of healthy controls.

  4. Production of sialylated O-linked glycans in Pichia pastoris.

    PubMed

    Hamilton, Stephen R; Cook, W James; Gomathinayagam, Sujatha; Burnina, Irina; Bukowski, John; Hopkins, Daniel; Schwartz, Shaina; Du, Min; Sharkey, Nathan J; Bobrowicz, Piotr; Wildt, Stefan; Li, Huijuan; Stadheim, Terrance A; Nett, Juergen H

    2013-10-01

    The methylotrophic yeast, Pichia pastoris, is an important organism used for the production of therapeutic proteins. Previously, we have reported the glycoengineering of this organism to produce human-like N-linked glycans but up to now no one has addressed engineering the O-linked glycosylation pathway. Typically, O-linked glycans produced by wild-type P. pastoris are linear chains of four to five α-linked mannose residues, which may be capped with β- or phospho-mannose. Previous genetic engineering of the N-linked glycosylation pathway of P. pastoris has eliminated both of these two latter modifications, resulting in O-linked glycans which are linear α-linked mannose structures. Here, we describe a method for the co-expression of an α-1,2-mannosidase, which reduces these glycans to primarily a single O-linked mannose residue. In doing so, we have reduced the potential of these glycans to interact with carbohydrate-binding proteins, such as dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin. Furthermore, the introduction of the enzyme protein-O-linked-mannose β-1,2-N-acetylglucosaminyltransferase 1, resulted in the capping of the single O-linked mannose residues with N-acetylglucosamine. Subsequently, this glycoform was extended into human-like sialylated glycans, similar in structure to α-dystroglycan-type glycoforms. As such, this represents the first example of sialylated O-linked glycans being produced in yeast and extends the utility of the P. pastoris production platform beyond N-linked glycosylated biotherapeutics to include molecules possessing O-linked glycans.

  5. Gp120 binding with DC-SIGN induces reactivation of HIV-1 provirus via the NF-κB signaling pathway.

    PubMed

    Jin, Changzhong; Li, Jie; Cheng, Linfang; Liu, Fumin; Wu, Nanping

    2016-03-01

    The reactivation mechanism of latent human immunodeficiency virus type 1 (HIV-1) infection is unclear, especially in dendritic cells (DC). DC-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) binds with HIV-1 and other pathogens to activate the extracellular regulated protein kinase (ERK) and nuclear factor-kappa B (NF-κB) pathways and regulate cytokine expression. We hypothesized that DC-SIGN-induced signaling pathways may activate HIV-1 provirus. To investigate this hypothesis, we generated a model by transfecting 293T cells with a DC-SIGN expression plasmid and an HIV-1 5' long terminal repeat (LTR) reporter plasmid, and then stimulated the 293T cells with HIV-1 gp120 protein, wild-type HIV-1 or VSV-G-pNL4.3 pseudotype virus (without gp120 protein). It was found that the HIV-1 5'LTR was reactivated by HIV-1 gp120 in DC-SIGN-expressing 293T cells. Then the HIV-1 chronically infected CEM-Bru cells were transfected with DC-SIGN expression plasmid and stimulated by HIV-1 gp120 protein. It was found that early and late HIV-1 provirus replication was reactivated by the HIV-1 gp120/DC-SIGN stimulation. We then investigated the involvement of the ERK, p38 mitogen-activated protein kinases and NF-κB signaling pathways in HIV-1 gp120/DC-SIGN-induced activation of HIV-1 provirus by inhibiting the pathways specifically. Our results indicated that HIV-1 gp120/DC-SIGN stimulation reactivates latent HIV-1 provirus via the NF-κB signal pathway.

  6. Human DC-SIGN binds specific human milk glycans.

    PubMed

    Noll, Alexander J; Yu, Ying; Lasanajak, Yi; Duska-McEwen, Geralyn; Buck, Rachael H; Smith, David F; Cummings, Richard D

    2016-05-15

    Human milk glycans (HMGs) are prebiotics, pathogen receptor decoys and regulators of host physiology and immune responses. Mechanistically, human lectins (glycan-binding proteins, hGBP) expressed by dendritic cells (DCs) are of major interest, as these cells directly contact HMGs. To explore such interactions, we screened many C-type lectins and sialic acid-binding immunoglobulin-like lectins (Siglecs) expressed by DCs for glycan binding on microarrays presenting over 200 HMGs. Unexpectedly, DC-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) showed robust binding to many HMGs, whereas other C-type lectins failed to bind, and Siglec-5 and Siglec-9 showed weak binding to a few glycans. By contrast, most hGBP bound to multiple glycans on other microarrays lacking HMGs. An α-linked fucose residue was characteristic of HMGs bound by DC-SIGN. Binding of DC-SIGN to the simple HMGs 2'-fucosyl-lactose (2'-FL) and 3-fucosyl-lactose (3-FL) was confirmed by flow cytometry to beads conjugated with 2'-FL or 3-FL, as well as the ability of the free glycans to inhibit DC-SIGN binding. 2'-FL had an IC50 of ∼1 mM for DC-SIGN, which is within the physiological concentration of 2'-FL in human milk. These results demonstrate that DC-SIGN among the many hGBP expressed by DCs binds to α-fucosylated HMGs, and suggest that such interactions may be important in influencing immune responses in the developing infant.

  7. Human Milk Blocks DC-SIGN-Pathogen Interaction via MUC1.

    PubMed

    Koning, Nathalie; Kessen, Sabine F M; Van Der Voorn, J Patrick; Appelmelk, Ben J; Jeurink, Prescilla V; Knippels, Leon M J; Garssen, Johan; Van Kooyk, Yvette

    2015-01-01

    Beneficial effects of breastfeeding are well-recognized and include both immediate neonatal protection against pathogens and long-term protection against allergies and autoimmune diseases. Although several proteins have been identified to have anti-viral or anti-bacterial effects like secretory IgA or lactoferrin, the mechanisms of immune modulation are not fully understood. Recent studies identified important beneficial effects of glycans in human milk, such as those expressed in oligosaccharides or on glycoproteins. Glycans are recognized by the carbohydrate receptors C-type lectins on dendritic cell (DC) and specific tissue macrophages, which exert important functions in immune modulation and immune homeostasis. A well-characterized C-type lectin is dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN), which binds terminal fucose. The present study shows that in human milk, MUC1 is the major milk glycoprotein that binds to the lectin domain of DC-SIGN and prevents pathogen interaction through the presence of Lewis x-type oligosaccharides. Surprisingly, this was specific for human milk, as formula, bovine or camel milk did not show any presence of proteins that interacted with DC-SIGN. The expression of DC-SIGN is found in young infants along the entire gastrointestinal tract. Our data thus suggest the importance of human milk glycoproteins for blocking pathogen interaction to DC in young children. Moreover, a potential benefit of human milk later in life in shaping the infants immune system through DC-SIGN cannot be ruled out.

  8. Functionally Graded Adhesives

    DTIC Science & Technology

    2009-11-01

    ASTM 907-05. Standard Terminology of Adhesives. West Conshohocken, PA, May 2005. 4. 3M Scotch-Grip Nitrile High Performance Rubber & Gasket Adhesive...distribution is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT The goal of this project was to increase rubber to metal adhesion in Army materials using...1 Figure 2. Steel and rubber

  9. PH dependent adhesive peptides

    SciTech Connect

    Tomich, John; Iwamoto, Takeo; Shen, Xinchun; Sun, Xiuzhi Susan

    2010-06-29

    A novel peptide adhesive motif is described that requires no receptor or cross-links to achieve maximal adhesive strength. Several peptides with different degrees of adhesive strength have been designed and synthesized using solid phase chemistries. All peptides contain a common hydrophobic core sequence flanked by positively or negatively charged amino acids sequences.

  10. Mini-review: barnacle adhesives and adhesion.

    PubMed

    Kamino, Kei

    2013-01-01

    Barnacles are intriguing, not only with respect to their importance as fouling organisms, but also in terms of the mechanism of underwater adhesion, which provides a platform for biomimetic and bioinspired research. These aspects have prompted questions regarding how adult barnacles attach to surfaces under water. The multidisciplinary and interdisciplinary nature of the studies makes an overview covering all aspects challenging. This mini-review, therefore, attempts to bring together aspects of the adhesion of adult barnacles by looking at the achievements of research focused on both fouling and adhesion. Biological and biochemical studies, which have been motivated mainly by understanding the nature of the adhesion, indicate that the molecular characteristics of barnacle adhesive are unique. However, it is apparent from recent advances in molecular techniques that much remains undiscovered regarding the complex event of underwater attachment. Barnacles attached to silicone-based elastomeric coatings have been studied widely, particularly with respect to fouling-release technology. The fact that barnacles fail to attach tenaciously to silicone coatings, combined with the fact that the mode of attachment to these substrata is different to that for most other materials, indicates that knowledge about the natural mechanism of barnacle attachment is still incomplete. Further research on barnacles will enable a more comprehensive understanding of both the process of attachment and the adhesives used. Results from such studies will have a strong impact on technology aimed at fouling prevention as well as adhesion science and engineering.

  11. Desmosomal adhesion in vivo.

    PubMed

    Berika, Mohamed; Garrod, David

    2014-02-01

    Desmosomes are intercellular junctions that provide strong adhesion or hyper-adhesion in tissues. Here, we discuss the molecular and structural basis of this with particular reference to the desmosomal cadherins (DCs), their isoforms and evolution. We also assess the role of DCs as regulators of epithelial differentiation. New data on the role of desmosomes in development and human disease, especially wound healing and pemphigus, are briefly discussed, and the importance of regulation of the adhesiveness of desmosomes in tissue dynamics is considered.

  12. Reversible Thermoset Adhesives

    NASA Technical Reports Server (NTRS)

    Mac Murray, Benjamin C. (Inventor); Tong, Tat H. (Inventor); Hreha, Richard D. (Inventor)

    2016-01-01

    Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry.

  13. Adhesion at metal interfaces

    NASA Technical Reports Server (NTRS)

    Banerjea, Amitava; Ferrante, John; Smith, John R.

    1991-01-01

    A basic adhesion process is defined, the theory of the properties influencing metallic adhesion is outlined, and theoretical approaches to the interface problem are presented, with emphasis on first-principle calculations as well as jellium-model calculations. The computation of the energies of adhesion as a function of the interfacial separation is performed; fully three-dimensional calculations are presented, and universality in the shapes of the binding energy curves is considered. An embedded-atom method and equivalent-crystal theory are covered in the framework of issues involved in practical adhesion.

  14. Adhesives, silver amalgam.

    PubMed

    1995-09-01

    The most recent advancement in silver amalgam is use of resin formulations to bond metal to tooth both chemically &/or physically, Since, historically, amalgam has been used successfully without adhesion to tooth, obvious clinical question is: Why is bonding now desirable? Two major clinical reasons to bond are: (1) Adhesive can increase fracture resistance of amalgam restored teeth & decrease cusp fractures; & (2) Seal provided by adhesive can greatly decrease, & often eliminate post-operative sensitivity. Following report summarizes CRA laboratory study of shear bond strength & sealing capability of 23 commercial adhesives used to bond 2 types of silver amalgam to tooth structure.

  15. Instant acting adhesive system

    NASA Technical Reports Server (NTRS)

    Davis, T. R.; Haines, R. C.

    1971-01-01

    Adhesive developes 80 percent of minimum bond strength of 250 psi less than 30 sec after activation is required. Adhesive is stable, handles easily, is a low toxic hazard, and is useful in industrial and domestic prototype bonding and clamping operations.

  16. LARC-13 adhesive development

    NASA Technical Reports Server (NTRS)

    Hill, S. G.; Sheppard, C. H.; Johnson, J. C.

    1980-01-01

    A LARC-13 type adhesive system was developed and property data obtained that demonstrated improved thermomechanical properties superior to base LARC-13 adhesive. An improved adhesive for 589 K (600 F) use was developed by physical or chemical modification of LARC-13. The adhesive was optimized for titanium and composite bonding, and a compatible surface preparation for titanium and composite substrates was identified. The data obtained with the improved adhesive system indicated it would meet the 589 K (600 F) properties desired for application on space shuttle components. Average titanium lap shear data were: (1) 21.1 MPa (3355 psi) at RT, (2) 13.0 MPa (1881 psi) at 600 F, and (3) 16.4 MPa (2335) after aging 125 hours at 600 F and tested at 600 F.

  17. Cyanoacrylate Adhesives in Eye Wounds.

    DTIC Science & Technology

    EYE, *WOUNDS AND INJURIES), (*ADHESIVES, EYE), (*ACRYLIC RESINS, ADHESIVES), CORNEA , HEALING, TISSUES(BIOLOGY), TOLERANCES(PHYSIOLOGY), NECROSIS, SURGICAL SUPPLIES, STRENGTH(PHYSIOLOGY), SURGERY, THERAPY

  18. Cytotoxicity of denture adhesives.

    PubMed

    de Gomes, Pedro Sousa; Figueiral, Maria Helena; Fernandes, Maria Helena R; Scully, Crispian

    2011-12-01

    Ten commercially available denture adhesives, nine soluble formulations (six creams, three powders) and one insoluble product (pad), were analyzed regarding the cytotoxicity profile in direct and indirect assays using L929 fibroblast cells. In the direct assay, fibroblasts were seeded over the surface of a thick adhesive gel (5%, creams; 2.5%, powders and pad). In the indirect assay, cells were cultured in the presence of adhesive extracts prepared in static and dynamic conditions (0.5-2%, creams; 0.25-1%, powders and pad). Cell toxicity was assessed for cell viability/proliferation (MTT assay) and cell morphology (observation of the F-actin cytoskeleton organization by confocal laser scanning microscopy). Direct contact of the L929 fibroblasts with the thick adhesive gels caused no, or only a slight, decrease in cell viability/proliferation. The adhesive extracts (especially those prepared in dynamic conditions) caused significantly higher growth inhibition of fibroblasts and, in addition, caused dose- and time-dependent effects, throughout the 6-72 h exposure time. Also, dose-dependent effects on cell morphology, with evident disruption of the F-actin cytoskeleton organization, were seen in the presence of most adhesives. In conclusion, the adhesives possessed different degrees of cytotoxicity, but similar dose- and time-dependent biological profiles.

  19. Adhesive Contact Sweeper

    NASA Technical Reports Server (NTRS)

    Patterson, Jonathan D.

    1993-01-01

    Adhesive contact sweeper removes hair and particles vacuum cleaner leaves behind, without stirring up dust. Also cleans loose rugs. Sweeper holds commercially available spools of inverted adhesive tape. Suitable for use in environments in which air kept free of dust; optics laboratories, computer rooms, and areas inhabited by people allergic to dust. For carpets, best used in tandem with vacuum cleaner; first pass with vacuum cleaner removes coarse particles, and second pass with sweeper extracts fine particles. This practice extends useful life of adhesive spools.

  20. Focal adhesions in osteoneogenesis

    PubMed Central

    Biggs, M.J.P; Dalby, M.J

    2010-01-01

    As materials technology and the field of tissue engineering advances, the role of cellular adhesive mechanisms, in particular the interactions with implantable devices, becomes more relevant in both research and clinical practice. A key tenet of medical device technology is to use the exquisite ability of biological systems to respond to the material surface or chemical stimuli in order to help develop next-generation biomaterials. The focus of this review is on recent studies and developments concerning focal adhesion formation in osteoneogenesis, with an emphasis on the influence of synthetic constructs on integrin mediated cellular adhesion and function. PMID:21287830

  1. [Endothelial cell adhesion molecules].

    PubMed

    Ivanov, A N; Norkin, I A; Puchin'ian, D M; Shirokov, V Iu; Zhdanova, O Iu

    2014-01-01

    The review presents current data concerning the functional role of endothelial cell adhesion molecules belonging to different structural families: integrins, selectins, cadherins, and the immunoglobulin super-family. In this manuscript the regulatory mechanisms and factors of adhesion molecules expression and distribution on the surface of endothelial cells are discussed. The data presented reveal the importance of adhesion molecules in the regulation of structural and functional state of endothelial cells in normal conditions and in pathology. Particular attention is paid to the importance of these molecules in the processes of physiological and pathological angiogenesis, regulation of permeability of the endothelial barrier and cell transmigration.

  2. Adhesion of Polymer Vesicles

    NASA Astrophysics Data System (ADS)

    Lin, John J.; Bates, Frank S.; Hammer, Daniel A.; Silas, James A.

    2005-07-01

    The adhesion and bending modulus of polybutadiene-poly(ethylene oxide) block copolymer vesicles made from a bidisperse mixture of polymers is measured using micropipette aspiration. The adhesion energy between biotinylated vesicles and avidin beads is modeled by incorporating the extension of the adhesive ligands above the surface brush of the vesicle according to the blob model of bidisperse polymer mixtures of Komura and Safran assuming the polymer brush at the surface of the vesicle is compact. The same model accurately reproduces the scaling of the bending modulus with polymer composition.

  3. Adhesive Bonding for Shelters

    DTIC Science & Technology

    1980-12-01

    weru uvaluated, the type of etch bath " sweetener " and the type of rinse\\water used. The type of etch bath " sweetener " was found to have a dramatic effect...EA9601NW Adhesives on 50521134 Bare Adherenas 39 13 Stress-Durability Behavior Sun-mary 40 14 Effect of Ltch Bath Sweetening Alloy on Interracial Durability...34"’ -,,• , •’• •"• " ,,,,, 9 Adhesive/Primer/Adherend Alloy/Surface Preparation Combinations Adherend OFPL Sweetening Rinse Adhesive:Primer Alloy Alloy

  4. Adhesives for Aerospace

    NASA Technical Reports Server (NTRS)

    Meade, L. E.

    1985-01-01

    The industry is hereby challenged to integrate adhesive technology with the total structure requirements in light of today's drive into automation/mechanization. The state of the art of adhesive technology is fairly well meeting the needs of the structural designers, the processing engineer, and the inspector, each on an individual basis. The total integration of these needs into the factory of the future is the next collective hurdle to be achieved. Improved processing parameters to fit the needs of automation/mechanization will necessitate some changes in the adhesive forms, formulations, and chemistries. Adhesives have, for the most part, kept up with the needs of the aerospace industry, normally leading the rest of the industry in developments. The wants of the aerospace industry still present a challenge to encompass all elements, achieving a totally integrated joined and sealed structural system. Better toughness with hot-wet strength improvements is desired. Lower cure temperatures, longer out times, and improved corrosion inhibition are desired.

  5. Optical adhesive property study

    SciTech Connect

    Sundvold, P.D.

    1996-01-01

    Tests were performed to characterize the mechanical and thermal properties of selected optical adhesives to identify the most likely candidate which could survive the operating environment of the Direct Optical Initiation (DOI) program. The DOI system consists of a high power laser and an optical module used to split the beam into a number of channels to initiate the system. The DOI requirements are for a high shock environment which current military optical systems do not operate. Five candidate adhesives were selected and evaluated using standardized test methods to determine the adhesives` physical properties. EC2216, manufactured by 3M, was selected as the baseline candidate adhesive based on the test results of the physical properties.

  6. Adhesion of Lunar Dust

    NASA Technical Reports Server (NTRS)

    Walton, Otis R.

    2007-01-01

    This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

  7. Epithelial adhesive junctions

    PubMed Central

    Capaldo, Christopher T.; Farkas, Attila E.

    2014-01-01

    Epithelial adhesive cell-to-cell contacts contain large, plasma membrane-spanning multiprotein aggregates that perform vital structural and signaling functions. Three prominent adhesive contacts are the tight junction, adherens junction, and the desmosome. Each junction type has unique cellular functions and a complex molecular composition. In this review, we comment on recent and exciting advances in our understanding of junction composition and function. PMID:24592313

  8. Visualizing and quantifying adhesive signals

    PubMed Central

    Sabouri-Ghomi, Mohsen; Wu, Yi; Hahn, Klaus; Danuser, Gaudenz

    2008-01-01

    Understanding the structural adaptation and signaling of adhesion sites in response to mechanical stimuli requires in situ characterization of the dynamic activation of a large number of adhesion components. Here, we review high resolution live cell imaging approaches to measure forces, assembly and interaction of adhesion components, and the activation of adhesion-mediated signals. We conclude by outlining computational multiplexing as a framework for the integration of these data into comprehensive models of adhesion signaling pathways. PMID:18586481

  9. Mannosyl Glycodendritic Structure Inhibits DC-SIGN-Mediated Ebola Virus Infection in cis and in trans

    PubMed Central

    Lasala, Fátima; Arce, Eva; Otero, Joaquín R.; Rojo, Javier; Delgado, Rafael

    2003-01-01

    We have designed a glycodendritic structure, BH30sucMan, that blocks the interaction between dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) and Ebola virus (EBOV) envelope. BH30sucMan inhibits DC-SIGN-mediated EBOV infection at nanomolar concentrations. BH30sucMan may counteract important steps of the infective process of EBOV and, potentially, of microorganisms shown to exploit DC-SIGN for cell entry and infection. PMID:14638512

  10. Platelet Adhesion under Flow

    PubMed Central

    Ruggeri, Zaverio M.

    2011-01-01

    Platelet adhesive mechanisms play a well-defined role in hemostasis and thrombosis, but evidence continues to emerge for a relevant contribution to other pathophysiological processes including inflammation, immune-mediated responses to microbial and viral pathogens, and cancer metastasis. Hemostasis and thrombosis are related aspects of the response to vascular injury, but the former protects from bleeding after trauma while the latter is a disease mechanism. In either situation, adhesive interactions mediated by specific membrane receptors support the initial attachment of single platelets to cellular and extracellular matrix constituents of the vessel wall and tissues. In the subsequent steps of thrombus growth and stabilization, adhesive interactions mediate platelet to platelet cohesion (aggregation) and anchoring to the fibrin clot. A key functional aspect of platelets is their ability to circulate in a quiescent state surveying the integrity of the inner vascular surface, coupled to a prompt reaction wherever alterations are detected. In many respects, therefore, platelet adhesion to vascular wall structures, to one another or to other blood cells are facets of the same fundamental biological process. The adaptation of platelet adhesive functions to the effects of blood flow is the main focus of this review. PMID:19191170

  11. Reduction of postoperative adhesion development.

    PubMed

    Diamond, Michael P

    2016-10-01

    Despite use of meticulous surgical techniques, and regardless of surgical access via laparotomy or laparoscopy, postoperative adhesions develop in the vast majority of women undergoing abdominopelvic surgery. Such adhesions represent not only adhesion reformation at sites of adhesiolysis, but also de novo adhesion formation at sites of surgical procedures. Application of antiadhesion adjuvants compliment the benefits of meticulous surgical techniques, providing an opportunity to further reduce postoperative adhesion development. Improved understanding of the pathophysiology of adhesion development and distinguishing variations in the molecular biologic mechanisms from adhesion-free peritoneal repair represent future opportunities to improve the reduction of postoperative adhesions. Optimization of the reduction of postoperative adhesions will likely require identification of unique, personalized approaches in each individual, representing interindividual variation in peritoneal repair processes.

  12. Magnetic field switchable dry adhesives.

    PubMed

    Krahn, Jeffrey; Bovero, Enrico; Menon, Carlo

    2015-02-04

    A magnetic field controllable dry adhesive device is manufactured. The normal adhesion force can be increased or decreased depending on the presence of an applied magnetic field. If the magnetic field is present during the entire normal adhesion test cycle which includes both applying a preloading force and measuring the pulloff pressure, a decrease in adhesion is observed when compared to when there is no applied magnetic field. Similarly, if the magnetic field is present only during the preload portion of the normal adhesion test cycle, a decrease in adhesion is observed because of an increased stiffness of the magnetically controlled dry adhesive device. When the applied magnetic field is present during only the pulloff portion of the normal adhesion test cycle, either an increase or a decrease in normal adhesion is observed depending on the direction of the applied magnetic field.

  13. Adhesion and wetting: Similarities and differences

    SciTech Connect

    Shanahan, M.E.R. )

    1991-10-01

    This article examines what is understood about adhesion and wetting both from the historical and scientific perspectives. Topics covered include mechanical adhesion, specific adhesion, chemical adhesion, adhesion by diffusion, the adsorption or wetting theory, bulk adhesion, the rheological theory, hysteresis effects in rubber adhesion, and hysteresis of wetting.

  14. Mapping cell surface adhesion by rotation tracking and adhesion footprinting

    NASA Astrophysics Data System (ADS)

    Li, Isaac T. S.; Ha, Taekjip; Chemla, Yann R.

    2017-03-01

    Rolling adhesion, in which cells passively roll along surfaces under shear flow, is a critical process involved in inflammatory responses and cancer metastasis. Surface adhesion properties regulated by adhesion receptors and membrane tethers are critical in understanding cell rolling behavior. Locally, adhesion molecules are distributed at the tips of membrane tethers. However, how functional adhesion properties are globally distributed on the individual cell’s surface is unknown. Here, we developed a label-free technique to determine the spatial distribution of adhesive properties on rolling cell surfaces. Using dark-field imaging and particle tracking, we extract the rotational motion of individual rolling cells. The rotational information allows us to construct an adhesion map along the contact circumference of a single cell. To complement this approach, we also developed a fluorescent adhesion footprint assay to record the molecular adhesion events from cell rolling. Applying the combination of the two methods on human promyelocytic leukemia cells, our results surprisingly reveal that adhesion is non-uniformly distributed in patches on the cell surfaces. Our label-free adhesion mapping methods are applicable to the variety of cell types that undergo rolling adhesion and provide a quantitative picture of cell surface adhesion at the functional and molecular level.

  15. Mapping cell surface adhesion by rotation tracking and adhesion footprinting

    PubMed Central

    Li, Isaac T. S.; Ha, Taekjip; Chemla, Yann R.

    2017-01-01

    Rolling adhesion, in which cells passively roll along surfaces under shear flow, is a critical process involved in inflammatory responses and cancer metastasis. Surface adhesion properties regulated by adhesion receptors and membrane tethers are critical in understanding cell rolling behavior. Locally, adhesion molecules are distributed at the tips of membrane tethers. However, how functional adhesion properties are globally distributed on the individual cell’s surface is unknown. Here, we developed a label-free technique to determine the spatial distribution of adhesive properties on rolling cell surfaces. Using dark-field imaging and particle tracking, we extract the rotational motion of individual rolling cells. The rotational information allows us to construct an adhesion map along the contact circumference of a single cell. To complement this approach, we also developed a fluorescent adhesion footprint assay to record the molecular adhesion events from cell rolling. Applying the combination of the two methods on human promyelocytic leukemia cells, our results surprisingly reveal that adhesion is non-uniformly distributed in patches on the cell surfaces. Our label-free adhesion mapping methods are applicable to the variety of cell types that undergo rolling adhesion and provide a quantitative picture of cell surface adhesion at the functional and molecular level. PMID:28290531

  16. Adhesive particle shielding

    DOEpatents

    Klebanoff, Leonard Elliott; Rader, Daniel John; Walton, Christopher; Folta, James

    2009-01-06

    An efficient device for capturing fast moving particles has an adhesive particle shield that includes (i) a mounting panel and (ii) a film that is attached to the mounting panel wherein the outer surface of the film has an adhesive coating disposed thereon to capture particles contacting the outer surface. The shield can be employed to maintain a substantially particle free environment such as in photolithographic systems having critical surfaces, such as wafers, masks, and optics and in the tools used to make these components, that are sensitive to particle contamination. The shield can be portable to be positioned in hard-to-reach areas of a photolithography machine. The adhesive particle shield can incorporate cooling means to attract particles via the thermophoresis effect.

  17. Natural Underwater Adhesives.

    PubMed

    Stewart, Russell J; Ransom, Todd C; Hlady, Vladimir

    2011-06-01

    The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)(3) coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent

  18. Natural Underwater Adhesives

    PubMed Central

    Stewart, Russell J.; Ransom, Todd C.; Hlady, Vladimir

    2011-01-01

    The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)3 coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent

  19. Elastomer toughened polyimide adhesives

    NASA Technical Reports Server (NTRS)

    St.clair, A. K.; St.clair, T. L. (Inventor)

    1983-01-01

    A rubber-toughened addition-type polyimide composition is disclosed which has excellent high temperature bonding characteristics in the fully cured state, and improved peel strength and adhesive fracture resistance physical property characteristics. The process for making the improved adhesive involves preparing the rubber containing amic acid prepolymer by chemically reacting an amine-terminated elastomer and an aromatic diamine with an aromatic dianhydride with which a reactive chain stopper anhydride was mixed, and utilizing solvent or mixture of solvents for the reaction.

  20. Adhesion in hydrogel contacts.

    PubMed

    Torres, J R; Jay, G D; Kim, K-S; Bothun, G D

    2016-05-01

    A generalized thermomechanical model for adhesion was developed to elucidate the mechanisms of dissipation within the viscoelastic bulk of a hyperelastic hydrogel. Results show that in addition to the expected energy release rate of interface formation, as well as the viscous flow dissipation, the bulk composition exhibits dissipation due to phase inhomogeneity morphological changes. The mixing thermodynamics of the matrix and solvent determines the dynamics of the phase inhomogeneities, which can enhance or disrupt adhesion. The model also accounts for the time-dependent behaviour. A parameter is proposed to discern the dominant dissipation mechanism in hydrogel contact detachment.

  1. Adhesion in hydrogel contacts

    NASA Astrophysics Data System (ADS)

    Torres, J. R.; Jay, G. D.; Kim, K.-S.; Bothun, G. D.

    2016-05-01

    A generalized thermomechanical model for adhesion was developed to elucidate the mechanisms of dissipation within the viscoelastic bulk of a hyperelastic hydrogel. Results show that in addition to the expected energy release rate of interface formation, as well as the viscous flow dissipation, the bulk composition exhibits dissipation due to phase inhomogeneity morphological changes. The mixing thermodynamics of the matrix and solvent determines the dynamics of the phase inhomogeneities, which can enhance or disrupt adhesion. The model also accounts for the time-dependent behaviour. A parameter is proposed to discern the dominant dissipation mechanism in hydrogel contact detachment.

  2. Metallic Adhesion and Bonding

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Smith, J. R.; Rose, J. H.

    1984-01-01

    Although metallic adhesion has played a central part in much tribological speculation, few quantitative theoretical calculations are available. This is in part because of the difficulties involved in such calculations and in part because the theoretical physics community is not particularly involved with tribology. The calculations currently involved in metallic adhesion are summarized and shown that these can be generalized into a scaled universal relationship. Relationships exist to other types of covalent bonding, such as cohesive, chemisorptive, and molecular bonding. A simple relationship between surface energy and cohesive energy is offered.

  3. Switchable bio-inspired adhesives

    NASA Astrophysics Data System (ADS)

    Kroner, Elmar

    2015-03-01

    Geckos have astonishing climbing abilities. They can adhere to almost any surface and can run on walls and even stick to ceilings. The extraordinary adhesion performance is caused by a combination of a complex surface pattern on their toes and the biomechanics of its movement. These biological dry adhesives have been intensely investigated during recent years because of the unique combination of adhesive properties. They provide high adhesion, allow for easy detachment, can be removed residue-free, and have self-cleaning properties. Many aspects have been successfully mimicked, leading to artificial, bio-inspired, patterned dry adhesives, and were addressed and in some aspects they even outperform the adhesion capabilities of geckos. However, designing artificial patterned adhesion systems with switchable adhesion remains a big challenge; the gecko's adhesion system is based on a complex hierarchical surface structure and on advanced biomechanics, which are both difficult to mimic. In this paper, two approaches are presented to achieve switchable adhesion. The first approach is based on a patterned polydimethylsiloxane (PDMS) polymer, where adhesion can be switched on and off by applying a low and a high compressive preload. The switch in adhesion is caused by a reversible mechanical instability of the adhesive silicone structures. The second approach is based on a composite material consisting of a Nickel- Titanium (NiTi) shape memory alloy and a patterned adhesive PDMS layer. The NiTi alloy is trained to change its surface topography as a function of temperature, which results in a change of the contact area and of alignment of the adhesive pattern towards a substrate, leading to switchable adhesion. These examples show that the unique properties of bio-inspired adhesives can be greatly improved by new concepts such as mechanical instability or by the use of active materials which react to external stimuli.

  4. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives.

    PubMed

    Purtov, Julia; Frensemeier, Mareike; Kroner, Elmar

    2015-11-04

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm(2) provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects.

  5. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives

    PubMed Central

    2015-01-01

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm2 provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects. PMID:26457864

  6. Wood Composite Adhesives

    NASA Astrophysics Data System (ADS)

    Gomez-Bueso, Jose; Haupt, Robert

    The global environment, in which phenolic resins are being used for wood composite manufacture, has changed significantly during the last decade. This chapter reviews trends that are driving the use and consumption of phenolic resins around the world. The review begins with recent data on volume usage and regional trends, followed by an analysis of factors affecting global markets. In a section on environmental factors, the impact of recent formaldehyde emission regulations is discussed. The section on economics introduces wood composite production as it relates to the available adhesive systems, with special emphasis on the technical requirement to improve phenolic reactivity. Advances in composite process technology are introduced, especially in regard to the increased demands the improvements place upon adhesive system performance. The specific requirements for the various wood composite families are considered in the context of adhesive performance needs. The results of research into current chemistries are discussed, with a review of recent findings regarding the mechanisms of phenolic condensation and acceleration. Also, the work regarding alternate natural materials, such as carbohydrates, lignins, tannins, and proteinaceous materials, is presented. Finally, new developments in alternative adhesive technologies are reported.

  7. Rapid adhesive bonding concepts

    NASA Technical Reports Server (NTRS)

    Stein, B. A.; Tyeryar, J. R.; Hodges, W. T.

    1984-01-01

    Adhesive bonding in the aerospace industry typically utilizes autoclaves or presses which have considerable thermal mass. As a consequence, the rates of heatup and cooldown of the bonded parts are limited and the total time and cost of the bonding process is often relatively high. Many of the adhesives themselves do not inherently require long processing times. Bonding could be performed rapidly if the heat was concentrated in the bond lines or at least in the adherends. Rapid adhesive bonding concepts were developed to utilize induction heating techniques to provide heat directly to the bond line and/or adherends without heating the entire structure, supports, and fixtures of a bonding assembly. Bonding times for specimens are cut by a factor of 10 to 100 compared to standard press bonding. The development of rapid adhesive bonding for lap shear specimens (per ASTM D1003 and D3163), for aerospace panel bonding, and for field repair needs of metallic and advanced fiber reinforced polymeric matrix composite structures are reviewed.

  8. 3-D foam adhesive deposition

    NASA Technical Reports Server (NTRS)

    Lemons, C. R.; Salmassy, O. K.

    1976-01-01

    Bonding method, which reduces amount and weight of adhesive, is applicable to foam-filled honeycomb constructions. Novel features of process include temperature-viscosity control and removal of excess adhesive by transfer to cellophane film.

  9. Coating Reduces Ice Adhesion

    NASA Technical Reports Server (NTRS)

    Smith, Trent; Prince, Michael; DwWeese, Charles; Curtis, Leslie

    2008-01-01

    The Shuttle Ice Liberation Coating (SILC) has been developed to reduce the adhesion of ice to surfaces on the space shuttle. SILC, when coated on a surface (foam, metal, epoxy primer, polymer surfaces), will reduce the adhesion of ice by as much as 90 percent as compared to the corresponding uncoated surface. This innovation is a durable coating that can withstand several cycles of ice growth and removal without loss of anti-adhesion properties. SILC is made of a binder composed of varying weight percents of siloxane(s), ethyl alcohol, ethyl sulfate, isopropyl alcohol, and of fine-particle polytetrafluoroethylene (PTFE). The combination of these components produces a coating with significantly improved weathering characteristics over the siloxane system alone. In some cases, the coating will delay ice formation and can reduce the amount of ice formed. SILC is not an ice prevention coating, but the very high water contact angle (greater than 140 ) causes water to readily run off the surface. This coating was designed for use at temperatures near -170 F (-112 C). Ice adhesion tests performed at temperatures from -170 to 20 F (-112 to -7 C) show that SILC is a very effective ice release coating. SILC can be left as applied (opaque) or buffed off until the surface appears clear. Energy dispersive spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS) data show that the coating is still present after buffing to transparency. This means SILC can be used to prevent ice adhesion even when coating windows or other objects, or items that require transmission of optical light. Car windshields are kept cleaner and SILC effectively mitigates rain and snow under driving conditions.

  10. Ceramic Adhesive for High Temperatures

    NASA Technical Reports Server (NTRS)

    Stevens, Everett G.

    1987-01-01

    Fused-silica/magnesium-phosphate adhesive resists high temperatures and vibrations. New adhesive unaffected by extreme temperatures and vibrations. Assuring direct bonding of gap filters to tile sidewalls, adhesive obviates expensive and time-consuming task of removal, treatment, and replacement of tiles.

  11. Adhesion Casting In Low Gravity

    NASA Technical Reports Server (NTRS)

    Noever, David A.; Cronise, Raymond J.

    1996-01-01

    Adhesion casting in low gravity proposed as technique for making new and improved materials. Advantages of low-gravity adhesion casting, in comparison with adhesion casting in normal Earth gravity, comes from better control over, and greater uniformity of, thicknesses of liquid films that form on and adhere to solid surfaces during casting.

  12. Gordon Conference on Microbial Adhesion

    DTIC Science & Technology

    1988-07-01

    immunity against certain pathogens, the role of exopolysaccharides in adhesion and the role of lectin-glycolipid interactions in adhesion. Have...pathogenesis? What governs the specificity of p; exopolysaccharides in adhesion to surfaces? This session emphasized the molecular aspects of

  13. Rapid Adhesive Bonding of Composites

    NASA Technical Reports Server (NTRS)

    Stein, B. A.; Tyeryar, J. R.; Fox, R. L.; Sterling, S. Elmo, Jr.; Buckley, J. D.; Inge, Spencer V., Jr.; Burcher, L. G.; Wright, Robert E., Jr.

    1986-01-01

    Strong bonds created in less time and with less power than use of conventional bonding methods. Rapid adhesive bonding (RAB) technique for composites uses high-frequency induction heating toroids to quickly heat metallic susceptor impregnated with thermoplastic adhesive or sandwiched between thermoset or thermoplastic adhesive cloths or films. Susceptor steel screen or perforated steel foil.

  14. Environmentally compliant adhesive joining technology

    SciTech Connect

    Tira, J.S.

    1996-08-01

    Adhesive joining offers one method of assembling products. Advantages of adhesive joining/assembly include distribution of applied forces, lighter weight, appealing appearance, etc. Selecting environmentally safe adhesive materials and accompanying processes is paramount in today`s business climate if a company wants to be environmentally conscious and stay in business. Four areas of adhesive joining (adhesive formulation and selection, surface preparation, adhesive bonding process, waste and pollution generation/cleanup/management) all need to be carefully evaluated before adhesive joining is selected for commercial as well as military products. Designing for six sigma quality must also be addressed in today`s global economy. This requires material suppliers and product manufacturers to work even closer together.

  15. [Fulminant adhesive arachnoiditis].

    PubMed

    Tomczykiewicz, Kazimierz; Stępień, Adam; Staszewski, Jacek; Sadowska, Marta; Bogusławska-Walecka, Romana

    2012-01-01

    Adhesive arachnoiditis is a rare disease with insidious course. It causes damage of the spinal cord and nerve roots. The causes of adhesive arachnoiditis include earlier traumatic injury of the spinal cord, surgery, intrathecal administration of therapeutic substances (e.g. anaesthetics, chemotherapy) or contrast media, bleeding, and inflammation. It can also be idiopathic or iatrogenic. We present the case of a 42-year-old patient with fulminant adhesive arachnoiditis which was provoked by spinal surgery and caused severe neurological disability with profound, progressive, flaccid paraparesis and bladder dysfunction. The electromyography (EMG) showed serious damage of nerves of both lower limbs at the level of motor roots L2-S2 and damage of the motor neuron at the level of Th11-Th12 on the right side. Magnetic resonance imaging of the lumbosacral and thoracic part of the spinal cord demonstrated cystic liquid spaces in the lumen of the dural sac in the bottom part of the cervical spine and at the Th2-Th10 level, modelling the lateral and anterior surface of the cord. Because of the vast lesions, surgery could not be performed. Conservative treatment and rehabilitation brought only a small clinical improvement.

  16. Development of phosphorylated adhesives

    NASA Technical Reports Server (NTRS)

    Bilow, N.; Giants, T. W.; Jenkins, R. K.; Campbell, P. L.

    1983-01-01

    The synthesis of epoxy prepolymers containing phosphorus was carried out in such a manner as to provide adhesives containing at least 5 percent of this element. The purpose of this was to impart fire retardant properties to the adhesive. The two epoxy derivatives, bis(4-glycidyl-oxyphenyl)phenylphosphine oxide and bis(4-glycidyl-2-methoxyphenyl)phenylphosphonate, and a curing agent, bis(3-aminophenyl)methylphosphine oxide, were used in conjunction with one another and along with conventional epoxy resins and curing agents to bond Tedlar and Polyphenylethersulfone films to Kerimid-glass syntactic foam-filled honeycomb structures. Elevated temperatures are required to cure the epoxy resins with the phosphorus-contaning diamine; however, when Tedlar is being bonded, lower curing temperatures must be used to avoid shrinkage and the concomitant formation of surface defects. Thus, the phosphorus-containing aromatic amine curing agent cannot be used alone, although it is possible to use it in conjunction with an aliphatic amine which would allow lower cure temperatures to be used. The experimental epoxy resins have not provided adhesive bonds quite as strong as those provided by Epon 828 when compared in peel tests, but the differences are not very significant. It should be noted, if optimum properties are to be realized. In any case the fire retardant characteristics of the neat resin systems obtained are quite pronounced, since in most cases the self-extinguishing properties are evident almost instantly when specimens are removed from a flame.

  17. Ceramic microstructure and adhesion

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1984-01-01

    When a ceramic is brought into contact with a ceramic, a polymer, or a metal, strong bond forces can develop between the materials. The bonding forces will depend upon the state of the surfaces, cleanliness and the fundamental properties of the two solids, both surface and bulk. Adhesion between a ceramic and another solid are discussed from a theoretical consideration of the nature of the surfaces and experimentally by relating bond forces to interface resulting from solid state contact. Surface properties of ceramics correlated with adhesion include, orientation, reconstruction and diffusion as well as the chemistry of the surface specie. Where a ceramic is in contact with a metal their interactive chemistry and bond strength is considered. Bulk properties examined include elastic and plastic behavior in the surficial regions, cohesive binding energies, crystal structures and crystallographic orientation. Materials examined with respect to interfacial adhesive interactions include silicon carbide, nickel zinc ferrite, manganese zinc ferrite, and aluminum oxide. The surfaces of the contacting solids are studied both in the atomic or molecularly clean state and in the presence of selected surface contaminants.

  18. Adhesion barrier reduces postoperative adhesions after cardiac surgery.

    PubMed

    Kaneko, Yukihiro; Hirata, Yasutaka; Achiwa, Ikuya; Morishita, Hiroyuki; Soto, Hajime; Kobayahsi, Jotaro

    2012-06-01

    Reoperation in cardiac surgery is associated with increased risk due to surgical adhesions. Application of a bioresorbable material could theoretically reduce adhesions and allow later development of a free dissection plane for cardiac reoperation. Twenty-one patients in whom a bioresorbable hyaluronic acid-carboxymethylcellulose adhesion barrier had been applied in a preceding surgery underwent reoperations, while 23 patients underwent reoperations during the same period without a prior adhesion barrier. Blinded observers graded the tenacity of the adhesions from surgical video recordings of the reoperations. No excessive bleeding requiring wound reexploration, mediastinal infection, or other complication attributable to the adhesion barrier occurred. Multiple regression analysis showed that shorter duration of the preceding surgery, non-use of cardiopulmonary bypass in the preceding surgery, and use of the adhesion barrier were significantly associated with less tenacious surgical adhesions. The use of a bioresorbable material in cardiac surgery reduced postoperative adhesions, facilitated reoperation, and did not promote complications. The use of adhesion barrier is recommended in planned staged procedures and those in which future reoperation is likely.

  19. Focal Adhesion Kinase Modulates Cell Adhesion Strengthening via Integrin Activation

    PubMed Central

    Michael, Kristin E.; Dumbauld, David W.; Burns, Kellie L.; Hanks, Steven K.

    2009-01-01

    Focal adhesion kinase (FAK) is an essential nonreceptor tyrosine kinase regulating cell migration, adhesive signaling, and mechanosensing. Using FAK-null cells expressing FAK under an inducible promoter, we demonstrate that FAK regulates the time-dependent generation of adhesive forces. During the early stages of adhesion, FAK expression in FAK-null cells enhances integrin activation to promote integrin binding and, hence, the adhesion strengthening rate. Importantly, FAK expression regulated integrin activation, and talin was required for the FAK-dependent effects. A role for FAK in integrin activation was confirmed in human fibroblasts with knocked-down FAK expression. The FAK autophosphorylation Y397 site was required for the enhancements in adhesion strengthening and integrin-binding responses. This work demonstrates a novel role for FAK in integrin activation and the time-dependent generation of cell–ECM forces. PMID:19297531

  20. Spinal adhesive arachnoiditis.

    PubMed

    Dolan, R A

    1993-06-01

    Forty-one cases of spinal adhesive arachnoiditis are presented. The key points are, first, that lumbar disc lesions, their investigations and surgical treatment and the use of nonabsorbable contrast materials are the most common etiological factors and, secondly, that operation is the best treatment. It is our contention that the majority of patients so treated do experience some improvement in what otherwise can be an unbearable amount of pain and disability. The use of adsorbable, nonirritative contrast materials such as Iohexol Parenteral will result in a marked reduction in the frequency of occurrence of arachnoiditis.

  1. CYANOACRYLATE ADHESIVES IN EYE WOUNDS.

    DTIC Science & Technology

    adhesives. The following adhesives were tested: methyl, isobutyl, n-butyl, n-hexyl, n-heptyl, n-octyl, n-decyl, -trifluoroisopropyl 2- cyanoacrylate , and...Biobond. Of these, methyl and -trifluoroisopropyl cyanoacrylates are not well tolerated by eye tissues. Biobond sets too slowly, and does not seem... cyanoacrylate is the best adhesive found so far when tissue tolerance, tensile strength, and ability to seal eye perforations (alone and with silicone rubber patches) are the criteria. (Author)

  2. Durability of Adhesively Bonded Structure

    DTIC Science & Technology

    1992-08-11

    frequently. Significant technology improvements have occurred In surface treatment, primers, joint analyses, adhesives and process controls. These have...clearly established the Initial cost savings potential for adhesive bonding. While this approach addresses the adequacy of joints early in service, there...processes with those changes which occur as a result of residual stress or cyclic loading in the adhesive joint 074-2R-bh 1 To fill a small part of this

  3. Hot melt adhesive attachment pad

    NASA Technical Reports Server (NTRS)

    Fox, R. L.; Frizzill, A. W.; Little, B. D.; Progar, D. J.; Coultrip, R. H.; Couch, R. H.; Gleason, J. R.; Stein, B. A.; Buckley, J. D.; St.clair, T. L. (Inventor)

    1984-01-01

    A hot melt adhesive attachment pad for releasably securing distinct elements together is described which is particularly useful in the construction industry or a spatial vacuum environment. The attachment pad consists primarily of a cloth selectively impregnated with a charge of hot melt adhesive, a thermo-foil heater, and a thermo-cooler. These components are securely mounted in a mounting assembly. In operation, the operator activates the heating cycle transforming the hot melt adhesive to a substantially liquid state, positions the pad against the attachment surface, and activates the cooling cycle solidifying the adhesive and forming a strong, releasable bond.

  4. Improved Adhesion and Compliancy of Hierarchical Fibrillar Adhesives.

    PubMed

    Li, Yasong; Gates, Byron D; Menon, Carlo

    2015-08-05

    The gecko relies on van der Waals forces to cling onto surfaces with a variety of topography and composition. The hierarchical fibrillar structures on their climbing feet, ranging from mesoscale to nanoscale, are hypothesized to be key elements for the animal to conquer both smooth and rough surfaces. An epoxy-based artificial hierarchical fibrillar adhesive was prepared to study the influence of the hierarchical structures on the properties of a dry adhesive. The presented experiments highlight the advantages of a hierarchical structure despite a reduction of overall density and aspect ratio of nanofibrils. In contrast to an adhesive containing only nanometer-size fibrils, the hierarchical fibrillar adhesives exhibited a higher adhesion force and better compliancy when tested on an identical substrate.

  5. Effect of adhesive thickness on adhesively bonded T-joint

    NASA Astrophysics Data System (ADS)

    Abdullah, A. R.; Afendi, Mohd; Majid, M. S. Abdul

    2013-12-01

    The aim of this work is to analyze the effect of adhesive thickness on tensile strength of adhesively bonded stainless steel T-joint. Specimens were made from SUS 304 Stainless Steel plate and SUS 304 Stainless Steel perforated plate. Four T-joint specimens with different adhesive thicknesses (0.5, 1.0, 1.5 and 2.0 mm) were made. Experiment result shows T-joint specimen with adhesive thickness of 1.0 mm yield highest maximum load. Identical T-joint specimen jointed by spot welding was also tested. Tensile test shows welded T-Joint had eight times higher tensile load than adhesively bonded T-joint. However, in low pressure application such as urea granulator chamber, high tensile strength is not mandatory. This work is useful for designer in fertilizer industry and others who are searching for alternative to spot welding.

  6. PED/PEA-15 interacts with the 67 kD laminin receptor and regulates cell adhesion, migration, proliferation and apoptosis

    PubMed Central

    Formisano, Pietro; Ragno, Pia; Pesapane, Ada; Alfano, Daniela; Alberobello, Anna Teresa; Rea, Vincenza Elena Anna; Giusto, Raffaella; Rossi, Francesca W; Beguinot, Francesco; Rossi, Guido; Montuori, Nunzia

    2012-01-01

    Abstract Phosphoprotein enriched in diabetes/phosphoprotein enriched in astrocytes-15 kD (PED/PEA-15) is an anti-apoptotic protein whose expression is increased in several human cancers. In addition to apoptosis, PED/PEA-15 is involved in the regulation of other major cellular functions, including cell adhesion, migration, proliferation and glucose metabolism. To further understand the functions of this protein, we performed a yeast two-hybrid screening using PED/PEA-15 as a bait and identified the 67 kD high-affinity laminin receptor (67LR) as an interacting partner. 67 kD laminin receptor is a non-integrin cell-surface receptor for the extracellular matrix (ECM), derived from the dimerization of a 37 kD cytosolic precursor (37LRP). The 67LR is highly expressed in human cancers and widely recognized as a molecular marker of metastatic aggressiveness. The molecular interaction of PED/PEA-15 with 67LR was confirmed by pull-down experiments with recombinant His-tagged 37LRP on lysates of PED/PEA-15 transfected HEK-293 cells. Further, overexpressed or endogenous PED/PEA-15 was co-immunoprecipitated with 67LR in PED/PEA-15-transfected HEK-293 cells and in U-373 glioblastoma cells, respectively. PED/PEA-15 overexpression significantly increased 67LR-mediated HEK-293 cell adhesion and migration to laminin that, in turn, determined PED/PEA-15 phosphorylation both in Ser-104 and Ser-116, thus enabling cell proliferation and resistance to apoptosis. PED/PEA-15 ability to induce cell responses to ECM-derived signals through interaction with 67LR may be of crucial importance for tumour cell survival in a poor microenvironment, thus favouring the metastatic spread and colonization. PMID:21895963

  7. Fire-Retardant Epoxy Adhesives

    NASA Technical Reports Server (NTRS)

    Bilow, N.; Giants, T. W.

    1982-01-01

    Phosphorus-containing epoxy is fire-retardant and translucent. Intended as adhesive for laminated plastic sheets, new material bonds well to titanium dioxide-filled plastic film, which ordinarily shows little surface interaction with adhesives. Fire retardancy has been demonstrated, and smoke density is low enough to avoid smoke obscuration.

  8. Measuring Adhesion And Friction Forces

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1991-01-01

    Cavendish balance adapted to new purpose. Apparatus developed which measures forces of adhesion and friction between specimens of solid materials in vacuum at temperatures from ambient to 900 degrees C. Intended primarily for use in studying adhesion properties of ceramics and metals, including silicon carbide, aluminum oxide, and iron-base amorphous alloys.

  9. Polymer Claw: Instant Underwater Adhesive

    DTIC Science & Technology

    2012-10-23

    pressure-activated adhesive is nearly complete. A 2:1 ratio of microcapsules:gorilla glue and a 1.5% dibutyltin diacetate concentration produced adhesion...Table I below. The best performers generally had between 1% and 1.5% dibutyltin diacetate (DBTDA). They also had a 2:1 ratio (vol/wt) of microcapsules

  10. Severe adhesive small bowel obstruction.

    PubMed

    Di Saverio, Salomone; Catena, Fausto; Kelly, Michael D; Tugnoli, Gregorio; Ansaloni, Luca

    2012-12-01

    Adhesive small bowel obstruction is a frequent cause of hospital admission. Water soluble contrast studies may have diagnostic and therapeutic value and avoid challenging demanding surgical operations, but if bowel ischemia is suspected, prompt surgical intervention is mandatory. A 58-year-old patient was operated for extensive adhesive small bowel obstruction after having had two previous laparotomies for colorectal surgery, and had a complex clinical course with multiple operations and several complications. Different strategies of management have been adopted, including non-operative management with the use of hyperosmolar water soluble contrast medium, multiple surgical procedures, total parenteral nutrition (TPN) support, and finally use of antiadherences icodextrin solution. After 2 years follow-up the patient was doing well without presenting recurrent episodes of adhesive small bowel obstruction. For patients admitted several times for adhesive small bowel obstruction, the relative risk of recurring obstruction increases in relation to the number of prior episodes. Several strategies for non-operative conservative management of adhesive small bowel obstruction have already addressed diagnostic and therapeutic value of hyperosmolar water soluble contrast. According to the most recent evidence-based guidelines, open surgery is the preferred method for surgical treatment of strangulating adhesive small bowel obstruction as well as after failed conservative management. Research interest and clinical evidence are increasing in adhesions prevention. Hyaluronic acid-carboxycellulose membrane and icodextrin may reduce incidence of adhesions.

  11. Inhibition of HIV-1 transmission in trans from dendritic cells to CD4+ T lymphocytes by natural antibodies to the CRD domain of DC-SIGN purified from breast milk and intravenous immunoglobulins

    PubMed Central

    Requena, Mary; Bouhlal, Hicham; Nasreddine, Nadine; Saidi, Hela; Gody, Jean-Chrysostome; Aubry, Sylvie; Grésenguet, Gérard; Kazatchkine, Michel D; Sekaly, Rafick-Pierre; Bélec, Laurent; Hocini, Hakim

    2008-01-01

    The present study demonstrates that human breast milk and normal human polyclonal immunoglobulins purified from plasma [intravenous immunoglobulins (IVIg)] contain functional natural immunoglobulin A (IgA) and IgG antibodies directed against the carbohydrate recognition domain (CRD) domain of the dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) molecule, which is involved in the binding of human immunodeficiency virus (HIV)-1 to dendritic cells (DCs). Antibodies to DC-SIGN CRD were affinity-purified on a matrix to which a synthetic peptide corresponding to the N-terminal CRD domain (amino-acid 342–amino-acid 371) had been coupled. The affinity-purified antibodies bound to the DC-SIGN peptide and to the native DC-SIGN molecule expressed by HeLa DC-SIGN+ cells and immature monocyte-derived dendritic cells (iMDDCs), in a specific and dose-dependent manner. At an optimal dose of 200 µg/ml, natural antibodies to DC-SIGN CRD peptide purified from breast milk and IVIg stained 25 and 20% of HeLa DC-SIGN+ cells and 32 and 12% of iMDDCs, respectively. Anti-DC-SIGN CRD peptide antibodies inhibited the attachment of virus to HeLa DC-SIGN by up to 78% and the attachment to iMDDCs by only 20%. Both breast milk- and IVIg-derived natural antibodies to the CRD peptide inhibited 60% of the transmission in trans of HIV-1JRCSF, an R5-tropic strain, from iMDDCs to CD4+ T lymphocytes. Taken together, these observations suggest that the attachment of HIV to DCs and transmission in trans to autologous CD4+ T lymphocytes occur through two independent mechanisms. Our data support a role of natural antibodies to DC-SIGN in the modulation of postnatal HIV transmission through breast-feeding and in the natural host defence against HIV-1 in infected individuals. PMID:17999675

  12. Brugia malayi Antigen (BmA) Inhibits HIV-1 Trans-Infection but Neither BmA nor ES-62 Alter HIV-1 Infectivity of DC Induced CD4+ Th-Cells

    PubMed Central

    Mouser, Emily E. I. M.; Pollakis, Georgios; Yazdanbakhsh, Maria; Harnett, William

    2016-01-01

    One of the hallmarks of HIV-1 disease is the association of heightened CD4+ T-cell activation with HIV-1 replication. Parasitic helminths including filarial nematodes have evolved numerous and complex mechanisms to skew, dampen and evade human immune responses suggesting that HIV-1 infection may be modulated in co-infected individuals. Here we studied the effects of two filarial nematode products, adult worm antigen from Brugia malayi (BmA) and excretory-secretory product 62 (ES-62) from Acanthocheilonema viteae on HIV-1 infection in vitro. Neither BmA nor ES-62 influenced HIV-1 replication in CD4+ enriched T-cells, with either a CCR5- or CXCR4-using virus. BmA, but not ES-62, had the capacity to bind the C-type lectin dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) thereby inhibiting HIV-1 trans-infection of CD4+ enriched T-cells. As for their effect on DCs, neither BmA nor ES-62 could enhance or inhibit DC maturation as determined by CD83, CD86 and HLA-DR expression, or the production of IL-6, IL-10, IL-12 and TNF-α. As expected, due to the unaltered DC phenotype, no differences were found in CD4+ T helper (Th) cell phenotypes induced by DCs treated with either BmA or ES-62. Moreover, the HIV-1 susceptibility of the Th-cell populations induced by BmA or ES-62 exposed DCs was unaffected for both CCR5- and CXCR4-using HIV-1 viruses. In conclusion, although BmA has the potential capacity to interfere with HIV-1 transmission or initial viral dissemination through preventing the virus from interacting with DCs, no differences in the Th-cell polarizing capacity of DCs exposed to BmA or ES-62 were observed. Neither antigenic source demonstrated beneficial or detrimental effects on the HIV-1 susceptibility of CD4+ Th-cells induced by exposed DCs. PMID:26808476

  13. Adhesive capsulitis of the shoulder.

    PubMed

    Neviaser, Andrew S; Neviaser, Robert J

    2011-09-01

    Adhesive capsulitis is characterized by painful, gradual loss of active and passive shoulder motion resulting from fibrosis and contracture of the joint capsule. Other shoulder pathology can produce a similar clinical picture, however, and must be considered. Management is based on the underlying cause of pain and stiffness, and determination of the etiology is essential. Subtle clues in the history and physical examination can help differentiate adhesive capsulitis from other conditions that cause a stiff, painful shoulder. The natural history of adhesive capsulitis is a matter of controversy. Management of true capsular restriction of motion (ie, true adhesive capsulitis) begins with gentle, progressive stretching exercises. Most patients improve with nonsurgical treatment. Indications for surgery should be individualized. Failure to obtain symptomatic improvement and continued functional disability following ≥6 months of physical therapy is a general guideline for surgical intervention. Diligent postoperative therapy to maintain motion is required to minimize recurrence of adhesive capsulitis.

  14. Hyaluronan-mediated cellular adhesion

    NASA Astrophysics Data System (ADS)

    Curtis, Jennifer

    2005-03-01

    Many cells surround themselves with a cushioning halo of polysaccharides that is further strengthened and organized by proteins. In fibroblasts and chrondrocytes, the primary component of this pericellular matrix is hyaluronan, a large linear polyanion. Hyaluronan production is linked to a variety of disease, developmental, and physiological processes. Cells manipulate the concentration of hyaluronan and hyaluronan receptors for numerous activities including modulation of cell adhesion, cell motility, and differentiation. Recent investigations by identify hyaluronan's role in mediating early-stage cell adhesion. An open question is how the cell removes the 0.5-10 micron thick pericellular matrix to allow for further mature adhesion events requiring nanometer scale separations. In this investigation, holographic optical tweezers are used to study the adhesion and viscoelastic properties of chondrocytes' pericellular matrix. Ultimately, we aim to shed further light on the spatial and temporal details of the dramatic transition from micron to nanometer gaps between the cell and its adhesive substrate.

  15. Corrugated pipe adhesive applicator apparatus

    DOEpatents

    Shirey, R.A.

    1983-06-14

    Apparatus for coating selected portions of the troughs of a corrugated pipe with an adhesive includes a support disposed within the pipe with a reservoir containing the adhesive disposed on the support. A pump, including a spout, is utilized for supplying the adhesive from the reservoir to a trough of the pipe. A rotatable applicator is supported on the support and contacts the trough of the pipe. The applicator itself is sized so as to fit within the trough, and contacts the adhesive in the trough and spreads the adhesive in the trough upon rotation. A trough shield, supported by the support and disposed in the path of rotation of the applicator, is utilized to prevent the applicator from contacting selected portions of the trough. A locator head is also disposed on the support and provides a way for aligning the spout, the applicator, and the trough shield with the trough. 4 figs.

  16. Corrugated pipe adhesive applicator apparatus

    DOEpatents

    Shirey, Ray A.

    1983-06-14

    Apparatus for coating selected portions of the troughs of a corrugated pipe within an adhesive includes a support disposed within the pipe with a reservoir containing the adhesive disposed on the support. A pump, including a spout, is utilized for supplying the adhesive from the reservoir to a trough of the pipe. A rotatable applicator is supported on the support and contacts the trough of the pipe. The applicator itself is sized so as to fit within the trough, and contacts the adhesive in the trough and spreads the adhesive in the trough upon rotation. A trough shield, supported by the support and disposed in the path of rotation of the applicator, is utilized to prevent the applicator from contacting selected portions of the trough. A locator head is also disposed on the support and provides a way for aligning the spout, the applicator, and the trough shield with the trough.

  17. Biological adhesives and fastening devices

    NASA Astrophysics Data System (ADS)

    Wolpert, H. D.

    2012-04-01

    Sea creatures are a leading source to some of the more interesting discoveries in adhesives. Because sea water naturally breaks down even the strongest conventional adhesive, an alternative is important that could be used in repairing or fabricating anything that might have regular contact with moisture such as: Repairing broken and shattered bones, developing a surgical adhesive, use in the dental work, repairing and building ships, and manufacturing plywood. Some of nature's prototypes include the common mussel, limpet, some bacteria and abalone. As we learn more about these adhesives we are also developing non adhesive fasteners, such as mimicked after studying the octopus, burdock burrs (i.e. Velcro®) and the gecko.

  18. Adhesion testing device

    NASA Technical Reports Server (NTRS)

    LaPeyronnie, Glenn M. (Inventor); Huff, Charles M. (Inventor)

    2010-01-01

    The present invention provides a testing apparatus and method for testing the adhesion of a coating to a surface. The invention also includes an improved testing button or dolly for use with the testing apparatus and a self aligning button hook or dolly interface on the testing apparatus. According to preferred forms, the apparatus and method of the present invention are simple, portable, battery operated rugged, and inexpensive to manufacture and use, are readily adaptable to a wide variety of uses, and provide effective and accurate testing results. The device includes a linear actuator driven by an electric motor coupled to the actuator through a gearbox and a rotatable shaft. The electronics for the device are contained in the head section of the device. At the contact end of the device, is positioned a self aligning button hook, attached below the load cell located on the actuator shaft.

  19. Propulsion by directional adhesion

    NASA Astrophysics Data System (ADS)

    Bush, John; Prakash, Manu

    2008-03-01

    The rough, hairy integument of water-walking arthropods is well known to be responsible for their water-repellency; we here consider its additional propulsive role. We demonstrate that the tilted flexible leg hairs of water-walking arthropods render the leg cuticle directionally anisotropic: contact lines advance most readily towards the leg tips. The dynamical role of the resulting unidirectional adhesion is explored, and yields new insight into the manner in which water-walking arthropods generate thrust, glide and leap from the free surface. We thus provide new rationale for the fundamental topological difference in the roughness on plants and insects, and suggest novel directions for biomimetic design of smart, hydrophobic surfaces.

  20. The adhesive properties of coacervated recombinant hybrid mussel adhesive proteins.

    PubMed

    Lim, Seonghye; Choi, Yoo Seong; Kang, Dong Gyun; Song, Young Hoon; Cha, Hyung Joon

    2010-05-01

    Marine mussels attach to substrates using adhesive proteins. It has been suggested that complex coacervation (liquid-liquid phase separation via concentration) might be involved in the highly condensed and non-water dispersed adhesion process of mussel adhesive proteins (MAPs). However, as purified natural MAPs are difficult to obtain, it has not been possible to experimentally validate the coacervation model. In the present work, we demonstrate complex coacervation in a system including recombinant MAPs and hyaluronic acid (HA). Our recombinant hybrid MAPs, fp-151 and fp-131, can be produced in large quantities, and are readily purified. We observed successful complex coacervation using cationic fp-151 or fp-131, and an anionic HA partner. Importantly, we found that highly condensed complex coacervates significantly increased the bulk adhesive strength of MAPs in both dry and wet environments. In addition, oil droplets were successfully engulfed using a MAP-based interfacial coacervation process, to form microencapsulated particles. Collectively, our results indicate that a complex coacervation system based on MAPs shows superior adhesive properties, combined with additional valuable features including liquid/liquid phase separation and appropriate viscoelasticity. Our microencapsulation system could be useful in the development of new adhesive biomaterials, including self-adhesive microencapsulated drug carriers, for use in biotechnological and biomedical applications.

  1. Tunicate-mimetic nanofibrous hydrogel adhesive with improved wet adhesion.

    PubMed

    Oh, Dongyeop X; Kim, Sangsik; Lee, Dohoon; Hwang, Dong Soo

    2015-07-01

    The main impediment to medical application of biomaterial-based adhesives is their poor wet adhesion strength due to hydration-induced softening and dissolution. To solve this problem, we mimicked the wound healing process found in tunicates, which use a nanofiber structure and pyrogallol group to heal any damage on its tunic under sea water. We fabricated a tunicate-mimetic hydrogel adhesive based on a chitin nanofiber/gallic acid (a pyrogallol acid) composite. The pyrogallol group-mediated cross-linking and the nanofibrous structures improved the dissolution resistance and cohesion strength of the hydrogel compared to the amorphous polymeric hydrogels in wet condition. The tunicate-mimetic adhesives showed higher adhesion strength between fully hydrated skin tissues than did fibrin glue and mussel-mimetic adhesives. The tunicate mimetic hydrogels were produced at low cost from recyclable and abundant raw materials. This tunicate-mimetic adhesive system is an example of how natural materials can be engineered for biomedical applications.

  2. Universal adhesives: the next evolution in adhesive dentistry?

    PubMed

    Alex, Gary

    2015-01-01

    Every so often a new material, technique, or technological breakthrough spurs a paradigm shift in the way dentistry is practiced. The development and evolution of reliable enamel and dentin bonding agents is one such example. Indeed, the so-called "cosmetic revolution" in dentistry blossomed in large part due to dramatic advances in adhesive technology. It is the ability to bond various materials in a reasonably predictable fashion to both enamel and dentin substrates that enables dentists to routinely place porcelain veneers, direct and indirect composites, and a plethora of other restorative and esthetic materials. In fact, the longevity and predictability of many (if not most) current restorative procedures is wholly predicated on the dentist's ability to bond various materials to tooth tissues. Adhesive systems have progressed from the largely ineffective systems of the 1970s and early 1980s to the relatively successful total- and self-etching systems of today. The latest players in the adhesive marketplace are the so-called "universal adhesives." In theory, these systems have the potential to significantly simplify and expedite adhesive protocols and may indeed represent the next evolution in adhesive dentistry. But what defines a universal system, and are all these new systems truly "universal" and everything they are claimed to be? This article will examine the origin, chemistry, strengths, weaknesses, and clinical relevance of this new genre of dental adhesives.

  3. Enhanced adhesion by gecko-inspired hierarchical fibrillar adhesives.

    PubMed

    Murphy, Michael P; Kim, Seok; Sitti, Metin

    2009-04-01

    The complex structures that allow geckos to repeatably adhere to surfaces consist of multilevel branching fibers with specialized tips. We present a novel technique for fabricating similar multilevel structures from polymer materials and demonstrate the fabrication of arrays of two- and three-level structures, wherein each level terminates in flat mushroom-type tips. Adhesion experiments are conducted on two-level fiber arrays on a 12-mm-diameter glass hemisphere, which exhibit both increased adhesion and interface toughness over one-level fiber samples and unstructured control samples. These adhesion enhancements are the result of increased surface conformation as well as increased extension during detachment.

  4. Wet Adhesion and Adhesive Locomotion of Snails on Anti-Adhesive Non-Wetting Surfaces

    PubMed Central

    Shirtcliffe, Neil J.; McHale, Glen; Newton, Michael I.

    2012-01-01

    Creating surfaces capable of resisting liquid-mediated adhesion is extremely difficult due to the strong capillary forces that exist between surfaces. Land snails use this to adhere to and traverse across almost any type of solid surface of any orientation (horizontal, vertical or inverted), texture (smooth, rough or granular) or wetting property (hydrophilic or hydrophobic) via a layer of mucus. However, the wetting properties that enable snails to generate strong temporary attachment and the effectiveness of this adhesive locomotion on modern super-slippy superhydrophobic surfaces are unclear. Here we report that snail adhesion overcomes a wide range of these microscale and nanoscale topographically structured non-stick surfaces. For the one surface which we found to be snail resistant, we show that the effect is correlated with the wetting response of the surface to a weak surfactant. Our results elucidate some critical wetting factors for the design of anti-adhesive and bio-adhesion resistant surfaces. PMID:22693563

  5. Contractility Modulates Cell Adhesion Strengthening Through Focal Adhesion Kinase and Assembly of Vinculin-Containing Focal Adhesions

    PubMed Central

    Dumbauld, David W.; Shin, Heungsoo; Gallant, Nathan D.; Michael, Kristin E.; Radhakrishna, Harish; García, Andrés J.

    2010-01-01

    Actin-myosin contractility modulates focal adhesion assembly, stress fiber formation, and cell migration. We analyzed the contributions of contractility to fibroblast adhesion strengthening using a hydrodynamic adhesion assay and micropatterned substrates to control cell shape and adhesive area. Serum addition resulted in adhesion strengthening to levels 30–40% higher than serum-free cultures. Inhibition of myosin light chain kinase or Rho-kinase blocked phosphorylation of myosin light chain to similar extents and eliminated the serum-induced enhancements in strengthening. Blebbistatin-induced inhibition of myosin II reduced serum-induced adhesion strength to similar levels as those obtained by blocking myosin light chain phosphorylation. Reductions in adhesion strengthening by inhibitors of contractility correlated with loss of vinculin and talin from focal adhesions without changes in integrin binding. In vinculin-null cells, inhibition of contractility did not alter adhesive force, whereas controls displayed a 20% reduction in adhesion strength, indicating that the effects of contractility on adhesive force are vinculin-dependent. Furthermore, in cells expressing FAK, inhibitors of contractility reduced serum-induced adhesion strengthening as well as eliminated focal adhesion assembly. In contrast, in the absence of FAK, these inhibitors did not alter adhesion strength or focal adhesion assembly. These results indicate that contractility modulates adhesion strengthening via FAK-dependent, vinculin-containing focal adhesion assembly. PMID:20205236

  6. Marine Bioinspired Underwater Contact Adhesion.

    PubMed

    Clancy, Sean K; Sodano, Antonio; Cunningham, Dylan J; Huang, Sharon S; Zalicki, Piotr J; Shin, Seunghan; Ahn, B Kollbe

    2016-05-09

    Marine mussels and barnacles are sessile biofouling organisms that adhere to a number of surfaces in wet environments and maintain remarkably strong bonds. Previous synthetic approaches to mimic biological wet adhesive properties have focused mainly on the catechol moiety, present in mussel foot proteins (mfps), and especially rich in the interfacial mfps, for example, mfp-3 and -5, found at the interface between the mussel plaque and substrate. Barnacles, however, do not use Dopa for their wet adhesion, but are instead rich in noncatecholic aromatic residues. Due to this anomaly, we were intrigued to study the initial contact adhesion properties of copolymerized acrylate films containing the key functionalities of barnacle cement proteins and interfacial mfps, for example, aromatic (catecholic or noncatecholic), cationic, anionic, and nonpolar residues. The initial wet contact adhesion of the copolymers was measured using a probe tack testing apparatus with a flat-punch contact geometry. The wet contact adhesion of an optimized, bioinspired copolymer film was ∼15.0 N/cm(2) in deionized water and ∼9.0 N/cm(2) in artificial seawater, up to 150 times greater than commercial pressure-sensitive adhesive (PSA) tapes (∼0.1 N/cm(2)). Furthermore, maximum wet contact adhesion was obtained at ∼pH 7, suggesting viability for biomedical applications.

  7. Adhesion molecules in vernal keratoconjunctivitis

    PubMed Central

    El-Asrar, A.; Geboes, K.; Al-Kharashi, S.; Tabbara, K.; Missotten, L.; Desmet, V.

    1997-01-01

    AIMS/BACKGROUND—Adhesion molecules play a key role in the selective recruitment of different leucocyte population to inflammatory sites. The purpose of the present study was to investigate the presence and distribution of adhesion molecules in the conjunctiva of patients with vernal keratoconjunctivitis (VKC).
METHODS—The presence and distribution of adhesion molecules were studied in 14 conjunctival biopsy specimens from seven patients with active VKC and in four normal conjunctival biopsy specimens. We used a panel of specific monoclonal antibodies (mAbs) directed against intercellular adhesion molecule-1 (ICAM-1), intercellular adhesion molecule-3 (ICAM-3), lymphocyte function associated antigen-1 (LFA-1), very late activation antigen-4 (VLA-4), vascular cell adhesion molecule-1 (VCAM-1), and endothelial leucocyte adhesion molecule-1 (ELAM-1). In addition, a panel of mAbs were used to characterise the composition of the inflammatory infiltrate.
RESULTS—In the normal conjunctiva, ICAM-1 was expressed on the vascular endothelium only, LFA-1 and ICAM-3 on epithelial and stromal mononuclear cells , and VLA-4 on stromal mononuclear cells. The expression of VCAM-1 and ELAM-1 was absent. The number of cells expressing adhesion molecules was found to be markedly increased in all VKC specimens. This was concurrent with a heavy inflammatory infiltrate. Strong ICAM-1 expression was induced on the basal epithelial cells, and vascular endothelial cells. Furthermore, ICAM-1 was expressed on stromal mononuclear cells. LFA-1 and ICAM-3 were expressed on the majority of epithelial and stromal infiltrating mononuclear cells. VLA-4 expression was noted on stromal mononuclear cells. Compared with controls, VKC specimens showed significantly more ICAM-3+, LFA-1+, and VLA-4+ cells. VCAM-1 and ELAM-1 were induced on the vascular endothelial cells.
CONCLUSIONS—Increased expression of adhesion molecules may play an important role in the pathogenesis of VKC.

 PMID

  8. Adhesive Performance of Biomimetic Adhesive-Coated Biologic Scaffolds

    PubMed Central

    Murphy, John L.; Vollenweider, Laura; Xu, Fangmin; Lee, Bruce P.

    2010-01-01

    Surgical repair of a discontinuity in traumatized or degenerated soft tissues is traditionally accomplished using sutures. A current trend is to reinforce this primary repair with surgical grafts, meshes, or patches secured with perforating mechanical devices (i.e., sutures, staples, or tacks). These fixation methods frequently lead to chronic pain and mesh detachment. We developed a series of biodegradable adhesive polymers that are synthetic mimics of mussel adhesive proteins (MAPs), composed of 3,4-dihydroxyphenylalanine (DOPA)-derivatives, polyethylene glycol (PEG), and polycaprolactone (PCL). These polymers can be cast into films, and their mechanical properties, extent of swelling, and degradation rate can be tailored through the composition of the polymers as well as blending with additives. When coated onto a biologic mesh used for hernia repair, these adhesive constructs demonstrated adhesive strengths significantly higher than fibrin glue. With further development, a pre-coated bioadhesive mesh may represent a new surgical option for soft tissue repair. PMID:20919699

  9. Green waxes, adhesives and lubricants.

    PubMed

    Li, W; Kong, X H; Ruan, M; Ma, F M; Jiang, Y F; Liu, M Z; Chen, Y; Zuo, X H

    2010-10-28

    General characteristics of waxes, adhesives and lubricants as well as the recent fundamental investigations on their physical and mechanical behaviour are introduced. The current R&D status for new type/generation of waxes, adhesives and lubricants from natural products is reviewed, with an emphasis on their tribological applications. In particular, some crucial issues and challenges relating to technological improvement and materials development are discussed. Based on the current predicted shortage of energy resources and environmental concerns, prospective research on the development of green waxes, adhesives and lubricants is suggested.

  10. Interfacial adhesion of carbon fibers

    NASA Technical Reports Server (NTRS)

    Bascom, Willard D.

    1987-01-01

    Relative adhesion strengths between AS4, AS1, and XAS carbon fibers and thermoplastic polymers were determined using the embedded single filament test. Polymers studied included polycarbonate, polyphenylene oxide, polyetherimide, polysulfone, polyphenylene oxide blends with polystyrene, and polycarbonate blends with a polycarbonate polysiloxane block copolymer. Fiber surface treatments and sizings improved adhesion somewhat, but adhesion remained well below levels obtained with epoxy matrices. An explanation for the differences between the Hercules and Grafil fibers was sought using X ray photon spectroscopy, wetting, scanning electron microscopy and thermal desorption analysis.

  11. Adhesives from modified soy protein

    DOEpatents

    Sun, Susan; Wang, Donghai; Zhong, Zhikai; Yang, Guang

    2008-08-26

    The, present invention provides useful adhesive compositions having similar adhesive properties to conventional UF and PPF resins. The compositions generally include a protein portion and modifying ingredient portion selected from the group consisting of carboxyl-containing compounds, aldehyde-containing compounds, epoxy group-containing compounds, and mixtures thereof. The composition is preferably prepared at a pH level at or near the isoelectric point of the protein. In other preferred forms, the adhesive composition includes a protein portion and a carboxyl-containing group portion.

  12. Notch-Mediated Cell Adhesion

    PubMed Central

    Murata, Akihiko; Hayashi, Shin-Ichi

    2016-01-01

    Notch family members are generally recognized as signaling molecules that control various cellular responses in metazoan organisms. Early fly studies and our mammalian studies demonstrated that Notch family members are also cell adhesion molecules; however, information on the physiological roles of this function and its origin is limited. In this review, we discuss the potential present and ancestral roles of Notch-mediated cell adhesion in order to explore its origin and the initial roles of Notch family members dating back to metazoan evolution. We hypothesize that Notch family members may have initially emerged as cell adhesion molecules in order to mediate multicellularity in the last common ancestor of metazoan organisms. PMID:26784245

  13. Photovoltaic module with adhesion promoter

    SciTech Connect

    Xavier, Grace

    2013-10-08

    Photovoltaic modules with adhesion promoters and methods for fabricating photovoltaic modules with adhesion promoters are described. A photovoltaic module includes a solar cell including a first surface and a second surface, the second surface including a plurality of interspaced back-side contacts. A first glass layer is coupled to the first surface by a first encapsulating layer. A second glass layer is coupled to the second surface by a second encapsulating layer. At least a portion of the second encapsulating layer is bonded directly to the plurality of interspaced back-side contacts by an adhesion promoter.

  14. Testing Adhesive Bonds to Cloths

    NASA Technical Reports Server (NTRS)

    Thomann, David G.

    1987-01-01

    Nondestructive tool simple and inexpensive. Easy-to-use tool nondestructively tests strength of adhesive bond between cloth and straight rigid edge. Developed for testing advanced flexible reusable surface insulation.

  15. Seafood delicacy makes great adhesive

    ScienceCinema

    Idaho National Laboratory - Frank Roberto, Heather Silverman

    2016-07-12

    Technology from Mother Nature is often hard to beat, so Idaho National Laboratory scientistsgenetically analyzed the adhesive proteins produced by blue mussels, a seafood delicacy. Afterobtaining full-length DNA sequences encoding these proteins, reprod

  16. Seafood delicacy makes great adhesive

    SciTech Connect

    Idaho National Laboratory - Frank Roberto, Heather Silverman

    2008-03-26

    Technology from Mother Nature is often hard to beat, so Idaho National Laboratory scientistsgenetically analyzed the adhesive proteins produced by blue mussels, a seafood delicacy. Afterobtaining full-length DNA sequences encoding these proteins, reprod

  17. Adhesive interactions between vesicles in the strong adhesion limit

    PubMed Central

    Ramachandran, Arun; Anderson, Travers H.; Leal, L. Gary; Israelachvili, Jacob N.

    2010-01-01

    We consider the adhesive interaction energy between a pair of vesicles in the strong adhesion limit, in which bending forces play a negligible role in determining vesicle shape compared to forces due to membrane stretching. Although force-distance or energy distance relationships characterizing adhesive interactions between fluid bilayers are routinely measured using the surface forces apparatus, the atomic force microscope and the biomembrane force probe, the interacting bilayers in these methods are supported on surfaces (e.g. mica sheet) and cannot be deformed. However, it is known that in a suspension, vesicles composed of the same bilayer can deform by stretching or bending, and can also undergo changes in volume. Adhesively interacting vesicles can thus form flat regions in the contact zone, which will result in an enhanced interaction energy as compared to rigid vesicles. The focus of this paper is to examine the magnitude of the interaction energy between adhesively interacting, deformed vesicles relative to free, undeformed vesicles as a function of the intervesicle separation. The modification of the intervesicle interaction energy due to vesicle deformability can be calculated knowing the undeformed radius of the vesicles, R0, the bending modulus kb, the area expansion modulus Ka, and the adhesive minimum WP(0) and separation DP(0) in the energy of interaction between two flat bilayers, which can be obtained from the force-distance measurements made using the above supported-bilayer methods. For vesicles with constant volumes, we show that adhesive potentials between non-deforming bilayers such as ∣WP(0)∣∼5×10−4mJ/m2, which are ordinarily considered weak in colloidal physics literature, can result in significantly deep (>10×) energy minima due to increase in vesicle area and flattening in the contact region. If the osmotic expulsion of water across the vesicles driven by the tense, stretched membrane in the presence of an osmotically active

  18. Polymer Claw: Instant Underwater Adhesive

    DTIC Science & Technology

    2012-08-27

    technology is the use of pressure sensitive microcapsules , which release reactive amine crosslinkers into an adhesive putty when pressed against the surface...CLEANING AGENT RHEOLOGY 3 3.3 PRESSURE-ACTIVATED ADHESIVE 5 3.3.1 PROCESSING IMPROVEMENTS 5 3.3.2 MICROCAPSULE DIAMETER 5 3.3.3 MICROCAPSULE /RESIN...to attain a reasonable shelf life (- l wk.). The microcapsule diameter has been halved in order to improve mixing in the pressure-activated

  19. Multi-Scale Biomimetic Adhesives

    DTIC Science & Technology

    2009-02-10

    Objectives: Same as originally stated 3. Status of Effort: Over the life of this grant, significant technical contributions have been made. When this...department of Defense as well, broadening our goals. 4. Accomplishments/New Findings (over the life of the grant): The mechanism of adhesion in the gecko...enabling microrobotics to explore extraterrestrial surfaces or harsh climates otherwise not accessible to man. In contrast to the adhesion seen in a rest

  20. Silorane adhesive system: a case report.

    PubMed

    Ruschel, Vanessa Carla; Baratieri, Luiz Narciso; Monteiro Júnior, Sylvio; Andrada, Mauro Amaral Caldeira de

    2014-01-01

    Silorane-based composite resin requires a specific adhesive system: a 2-step self-etching adhesive. Clinical protocols are well established and are based on the principles of adhesion to mineralized dental tissues. In this paper, we present a clinical application of the silorane adhesive system in a class-II restoration using silorane-based composite resin.

  1. Fibrillar Adhesive for Climbing Robots

    NASA Technical Reports Server (NTRS)

    Pamess, Aaron; White, Victor E.

    2013-01-01

    A climbing robot needs to use its adhesive patches over and over again as it scales a slope. Replacing the adhesive at each step is generally impractical. If the adhesive or attachment mechanism cannot be used repeatedly, then the robot must carry an extra load of this adhesive to apply a fresh layer with each move. Common failure modes include tearing, contamination by dirt, plastic deformation of fibers, and damage from loading/ unloading. A gecko-like fibrillar adhesive has been developed that has been shown useful for climbing robots, and may later prove useful for grasping, anchoring, and medical applications. The material consists of a hierarchical fibrillar structure that currently contains two levels, but may be extended to three or four levels in continuing work. The contacting level has tens of thousands of microscopic fibers made from a rubberlike material that bend over and create intimate contact with a surface to achieve maximum van der Waals forces. By maximizing the real area of contact that these fibers make and minimizing the bending energy necessary to achieve that contact, the net amount of adhesion has been improved dramatically.

  2. Integrin-mediated adhesion complex

    PubMed Central

    Sebé-Pedrós, Arnau

    2010-01-01

    The integrin-mediated adhesion machinery is the primary cell-matrix adhesion mechanism in Metazoa. The integrin adhesion complex, which modulates important aspects of the cell physiology, is composed of integrins (alpha and beta subunits) and several scaffolding and signaling proteins. Integrins appeared to be absent in all non-metazoan eukaryotes so-far analyzed, including fungi, plants and choanoflagellates, the sister-group to Metazoa. Thus, integrins and, therefore, the integrin-mediated adhesion and signaling mechanism was considered a metazoan innovation. Recently, a broad comparative genomic analysis including new genome data from several unicellular organisms closely related to fungi and metazoans shattered previous views. The integrin adhesion and signaling complex is not specific to Metazoa, but rather it is present in apusozoans and holozoan protists. Thus, this important signaling and adhesion system predated the origin of Fungi and Metazoa, and was subsequently lost in fungi and choanoflagellates. This finding suggests that cooption played a more important role in the origin of Metazoa than previously believed. Here, we hypothesize that the integrin adhesome was ancestrally involved in signaling. PMID:21057645

  3. Bond strength of adhesive resin cement with different adhesive systems

    PubMed Central

    Lorenzoni e Silva, Fabrizio; Pamato, Saulo; Kuga, Milton-Carlos; Só, Marcus-Vinicius-Reis

    2017-01-01

    Background To assess the immediate bond strength of a dual-cure adhesive resin cement to the hybridized dentin with different bonding systems. Material and Methods Fifty-six healthy human molars were randomly divided into 7 groups (n=8). After 3 longitudinal sections, the central cuts were included in PVC matrix and were submitted to dentin hybridization according to the groups: G1 - etch & rinse system with 3-step (Apder™ Scotchbond™ Multi-Purpose, 3M ESPE), G2 - etch & rinse system with 3-step (Optibond™ FL, Kerr), G3 - etch & rinse system with 3-step (All-Bond 3®, Bisco), G4 - etch & rinse simplified system (Adper™ Single Bond 2, 3M ESPE), G5 - self-etching system with one step (Bond Force, Tokuyama), G6 - universal system in moist dentin (Single Bond Universal, 3M ESPE), G7 - universal system in dry dentin (Single Bond Universal, 3M ESPE). Then all groups received the cementing of a self-adhesive resin cement cylinder (Duo-link, Bisco) made from a polypropylene matrix. In the evaluation of bond strength, the samples were subjected to the microshear test and evaluated according to the fracture pattern by optical microscopy. Results The Kruskal-Wallis test suggests a statistically significant difference between groups (p=0,039), and Tukey for multiple comparisons, indicating a statistically significant difference between G3 and G4 (p<0.05). It was verified high prevalence of adhesive failures, followed by mixed failure and cohesive in dentin. Conclusions The technique and the system used to dentin hybridization are able to affect the immediate bond strength of resin cement dual adhesive. Key words:Adhesion, adhesive resin cement, adhesive systems, microshear. PMID:28149471

  4. [Adhesive lumbar arachnoiditis].

    PubMed

    Ribeiro, C; Reis, F C

    1998-01-01

    Spinal arachnoiditis, an inflammatory process involving all three meningeal layers as well as the nerve roots, is a cause of persistent symptoms in 6% to 16% of postoperative patients. Although spinal surgery is the most common antecedent associated with arachnoiditis, multiple causes have been reported, including infection, intrathecal steroids or anesthetic agents, trauma, subarachnoid hemorrhage and ionic myelographic contrast material--both oil soluble and water soluble. In the past, oil-based intrathecal contrast agents (Pantopaque) were associated with arachnoiditis especially when this material was introduced into the thecal sac and mixed with blood. Arachnoiditis is apparently rarely idiopathic. The pathogenesis of spinal arachnoiditis is similar to the repair process of serous membranes, such as the peritoneum, with a negligible inflammatory cellular exudate and a prominent fibrinous exudate. Chronic adhesive arachnoiditis of the lower spine is a myelographic diagnosis. The myelographic findings of arachnoiditis were divided into two types by Jorgensen et al. In type 1, "the empty thecal sac" appearance, there is homogeneous filling of the thecal sac with either absence of or defects involving nerve root sleeve filling. In type 2 arachnoiditis, there are localized or diffuse filling defects within the contrast column. MRI has demonstrated a sensitivity of 92% and a specificity of 100% in the diagnosis of arachnoiditis. The appearance of arachnoiditis on MRI can be assigned to three main groups. The MRI findings in group I are a conglomeration of adherent roots positioned centrally in the thecal sac. Patients in group II show roots peripherally adherent to the meninges--the so called empty sac. MRI findings in group III are a soft tissue mass within the subarachnoid space. It corresponds to the type 2 categorization defined by Jorgensen et al, where as the MRI imaging types I and II correspond to the myelographic type 1.

  5. Investigation of organic adhesives for hybrid microcircuits

    NASA Technical Reports Server (NTRS)

    Perkins, K. L.; Licari, J. J.

    1975-01-01

    The properties of organic adhesives were investigated to acquire information for a guideline document regarding the selection of adhesives for use in high reliability hybrid microcircuits. Specifically, investigations were made of (1) alternate methods for determining the outgassing of cured adhesives, (2) effects of long term aging at 150 C on the electrical properties of conductive adhesives, (3) effects of shelf life age on adhesive characteristics, (4) bond strengths of electrically conductive adhesives on thick film gold metallization, (5) a copper filled adhesive, (6) effects of products outgassed from cured adhesives on device electrical parameters, (7) metal migration from electrically conductive adhesives, and (8) ionic content of electrically insulative adhesives. The tests performed during these investigations are described, and the results obtained are discussed.

  6. Plasma polymerization for cell adhesive/anti-adhesive implant coating

    NASA Astrophysics Data System (ADS)

    Meichsner, Juergen; Testrich, Holger; Rebl, Henrike; Nebe, Barbara

    2015-09-01

    Plasma polymerization of ethylenediamine (C2H8N2, EDA) and perfluoropropane (C3F8, PFP) with admixture of argon and hydrogen, respectively, was studied using an asymmetric 13.56 MHz CCP. The analysis of the plasma chemical gas phase processes for stable molecules revealed consecutive reactions: C2H8N2 consumption, intermediate product NH3, and main final product HCN. In C3F8- H2 plasma the precursor molecule C3F8 and molecular hydrogen are consumed and HF as well as CF4 and C2F6 are found as main gaseous reaction products. The deposited plasma polymer films on the powered electrode are strongly cross-linked due to ion bombardment. The stable plasma polymerized films from EDA are characterized by high content of nitrogen with N/C ratio of about 0.35. The plasma polymerized fluorocarbon film exhibit a reduced F/C ratio of about 1.2. Adhesion tests with human osteoblast cell line MG-63 on coated Ti6Al4V samples (polished) compared with uncoated reference sample yielded both, the enhanced cell adhesion for plasma polymerized EDA and significantly reduced cell adhesion for fluorocarbon coating, respectively. Aging of the plasma polymerized EDA film, in particular due to the reactions with oxygen from air, showed no significant change in the cell adhesion. The fluorocarbon coating with low cell adhesion is of interest for temporary implants. Funded by the Campus PlasmaMed.

  7. Innovative Electrostatic Adhesion Technologies

    NASA Technical Reports Server (NTRS)

    Bryan, Tom; Macleod, Todd; Gagliano, Larry; Williams, Scott; McCoy, Brian

    2015-01-01

    Developing specialized Electro-Static grippers (commercially used in Semiconductor Manufacturing and in package handling) will allow gentle and secure Capture, Soft Docking, and Handling of a wide variety of materials and shapes (such as upper-stages, satellites, arrays, and possibly asteroids) without requiring physical features or cavities for a pincher or probe or using harpoons or nets. Combined with new rigid boom mechanisms or small agile chaser vehicles, flexible, high speed Electro-Static Grippers can enable compliant capture of spinning objects starting from a safe stand-off distance. Electroadhesion (EA) can enable lightweight, ultra-low-power, compliant attachment in space by using an electrostatic force to adhere similar and dissimilar surfaces. A typical EA enabled device is composed of compliant space-rated materials, such as copper-clad polyimide encapsulated by polymers. Attachment is induced by strong electrostatic forces between any substrate material, such as an exterior satellite panel and a compliant EA gripper pad surface. When alternate positive and negative charges are induced in adjacent planar electrodes in an EA surface, the electric fields set up opposite charges on the substrate and cause an electrostatic adhesion between the electrodes and the induced charges on the substrate. Since the electrodes and the polymer are compliant and can conform to uneven or rough surfaces, the electrodes can remain intimately close to the entire surface, enabling high clamping pressures. Clamping pressures of more than 3 N/cm2 in shear can be achieved on a variety of substrates with ultra-low holding power consumption (measured values are less than 20 microW/Newton weight held). A single EA surface geometry can be used to clamp both dielectric and conductive substrates, with slightly different physical mechanisms. Furthermore EA clamping requires no normal force be placed on the substrate, as conventional docking requires. Internally funded research and

  8. Innovative Electrostatic Adhesion Technologies

    NASA Astrophysics Data System (ADS)

    Gagliano, L.; Bryan, T.; Williams, S.; McCoy, B.; MacLeod, T.

    Developing specialized Electro-Static grippers (commercially used in Semiconductor Manufacturing and in package handling) will allow gentle and secure Capture, Soft Docking, and Handling of a wide variety of materials and shapes (such as upper-stages, satellites, arrays, and possibly asteroids) without requiring physical features or cavities for a pincher or probe or using harpoons or nets. Combined with new rigid boom mechanisms or small agile chaser vehicles, flexible, high speed Electro-Static Grippers can enable compliant capture of spinning objects starting from a safe stand-off distance. Electroadhesion (EA) can enable lightweight, ultra-low-power, compliant attachment in space by using an electrostatic force to adhere similar and dissimilar surfaces. A typical EA enabled device is composed of compliant space-rated materials, such as copper-clad polyimide encapsulated by polymers. Attachment is induced by strong electrostatic forces between any substrate material, such as an exterior satellite panel and a compliant EA surface. When alternate positive and negative charges are induced in adjacent planar electrodes in an EA surface, the electric fields set up opposite charges on the substrate and cause an electrostatic adhesion between the electrodes and the induced charges on the substrate. Since the electrodes and the polymer are compliant and can conform to uneven or rough surfaces, the electrodes can remain intimately close to the entire surface, enabling high clamping pressures. Clamping pressures of more than 3 N/cm2 in shear can be achieved on a variety of substrates with ultra-low holding power consumption (measured values are less than 20 microW/Newton weight held). A single EA surface geometry can be used to clamp both dielectric and conductive substrates, with slightly different physical mechanisms. Furthermore EA clamping requires no normal force be placed on the substrate, as conventional docking requires. Internally funded research and development

  9. Capillarity-based switchable adhesion.

    PubMed

    Vogel, Michael J; Steen, Paul H

    2010-02-23

    Drawing inspiration from the adhesion abilities of a leaf beetle found in nature, we have engineered a switchable adhesion device. The device combines two concepts: The surface tension force from a large number of small liquid bridges can be significant (capillarity-based adhesion) and these contacts can be quickly made or broken with electronic control (switchable). The device grabs or releases a substrate in a fraction of a second via a low-voltage pulse that drives electroosmotic flow. Energy consumption is minimal because both the grabbed and released states are stable equilibria that persist with no energy added to the system. Notably, the device maintains the integrity of an array of hundreds to thousands of distinct interfaces during active reconfiguration from droplets to bridges and back, despite the natural tendency of the liquid toward coalescence. We demonstrate the scaling of adhesion strength with the inverse of liquid contact size. This suggests that strengths approaching those of permanent bonding adhesives are possible as feature size is scaled down. In addition, controllability is fast and efficient because the attachment time and required voltage also scale down favorably. The device features compact size, no solid moving parts, and is made of common materials.

  10. [Adhesion molecules and diabetes mellitus].

    PubMed

    Urso, C; Hopps, E; Caimi, G

    2010-01-01

    Adhesion molecules play a significant role in leukocyte migration across the endothelium and are also involved in regulating immune system. It is shown that diabetic patients have an increase of soluble adhesion molecules (sICAM-1, sICAM-2, sVCAM-1, sE-selectin, sL-selectin, sP-selectin) considered an integral part of inflammatory state. This inflammation is responsible for the increased cardiovascular risk of these patients. There is a close link between hyperglycemia, oxidative stress, coagulopathy and inflammation and between these factors and the vascular damage. Various studies have showed the potential role of adhesion molecules in the pathogenesis of diabetic vasculopathy. They promote leukocyte recruitment, which is one of the initial steps in the genesis of atherosclerotic plaque. Adhesion molecules are also involved in the pathogenesis of diabetes mellitus type 1; sICAM-1 would have a particular immunomodulatory role in the process of destroying beta-cells and could be used as a subclinical marker of insulitis. Plasma levels of soluble adhesion molecules correlate with hyperglycemia, insulin resistance, dyslipidemia and obesity; they are associated with the development of nephropathy, retinopathy, myocardial infarction, stroke and obliterant peripheral arterial disease in diabetic type 1 and 2. Given the role of these molecules in endothelial dysfunction genesis and tissue damage associated with diabetes, they could constitute a therapeutic target for the prevention of genesis and progression of chronic complications of diabetic disease.

  11. High performance Cu adhesion coating

    SciTech Connect

    Lee, K.W.; Viehbeck, A.; Chen, W.R.; Ree, M.

    1996-12-31

    Poly(arylene ether benzimidazole) (PAEBI) is a high performance thermoplastic polymer with imidazole functional groups forming the polymer backbone structure. It is proposed that upon coating PAEBI onto a copper surface the imidazole groups of PAEBI form a bond with or chelate to the copper surface resulting in strong adhesion between the copper and polymer. Adhesion of PAEBI to other polymers such as poly(biphenyl dianhydride-p-phenylene diamine) (BPDA-PDA) polyimide is also quite good and stable. The resulting locus of failure as studied by XPS and IR indicates that PAEBI gives strong cohesive adhesion to copper. Due to its good adhesion and mechanical properties, PAEBI can be used in fabricating thin film semiconductor packages such as multichip module dielectric (MCM-D) structures. In these applications, a thin PAEBI coating is applied directly to a wiring layer for enhancing adhesion to both the copper wiring and the polymer dielectric surface. In addition, a thin layer of PAEBI can also function as a protection layer for the copper wiring, eliminating the need for Cr or Ni barrier metallurgies and thus significantly reducing the number of process steps.

  12. Flexible backbone aromatic polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Progar, Donald J.; St. Clair, Terry L.

    1989-01-01

    Continuing research at Langley Research Center on the synthesis and development of new inexpensive flexible aromatic polyimides as adhesives has resulted in a material identified as LARC-F-SO2 with similarities to polyimidesulfone, PISO2, and other flexible backbone polyimides recently reported by Progar and St. Clair. Also prepared and evaluated was an endcapped version of PISO2. These two polymers were compared with LARC-TPI and LARC-STPI, polyimides research in our laboratory and reported in the literature. The adhesive evaluation, primarily based on lap shear strength (LSS) tests at RT, 177 C and 204 C, involved preparing adhesive tapes, conducting bonding studies and exposing lap shear specimens to 204 C air for up to 1000 hrs and to a 72-hour water boil. The type of adhesive failure as well as the Tg was determined for the fractured specimens. The results indicate that LARC-TPI provides the highest LSSs. LARC-F-SO2, LARC-TPI and LARC-STPI all retain their strengths after thermal exposure for 1000 hrs and PISO2 retains greater than 80 percent of its control strengths. After a 72-hr water boil exposure, most of the four adhesive systems showed reduced strengths for all test temperatures although still retaining a high percentage of their original strength (greater than 60 percent) except for one case. The predominant failure type was cohesive with no significant change in the Tgs.

  13. Flexible backbone aromatic polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Progar, Donald J.; St.clair, Terry L.

    1988-01-01

    Continuing research at Langley Research Center on the synthesis and development of new inexpensive flexible aromatic polyimides as adhesives has resulted in a material identified as LARC-F-SO2 with similarities to polyimidesulfone, PISO2, and other flexible backbone polyimides recently reported by Progar and St. Clair. Also prepared and evaluated was an endcapped version of PISO2. These two polymers were compared with LARC-TPI and LARC-STPI, polyimides research in our laboratory and reported in the literature. The adhesive evaluation, primarily based on lap shear strength (LSS) tests at RT, 177 C and 204 C, involved preparing adhesive tapes, conducting bonding studies and exposing lap shear specimens to 204 C air for up to 1000 hrs and to a 72-hour water boil. The type of adhesive failure as well as the Tg was determined for the fractured specimens. The results indicate that LARC-TPI provides the highest LSSs. LARC-F-SO2, LARC-TPI and LARC-STPI all retain their strengths after thermal exposure for 1000 hrs and PISO2 retains greater than 80 percent of its control strengths. After a 72-hr water boil exposure, most of the four adhesive systems showed reduced strengths for all test temperatures although still retaining a high percentage of their original strength (greater than 60 percent) except for one case. The predominant failure type was cohesive with no significant change in the Tgs.

  14. Interfacial adhesion - Theory and experiment

    NASA Technical Reports Server (NTRS)

    Ferrante, John; Banerjea, Amitava; Bozzolo, Guillermo H.; Finley, Clarence W.

    1988-01-01

    Adhesion, the binding of different materials at an interface, is of general interest to many branches of technology, e.g., microelectronics, tribology, manufacturing, construction, etc. However, there is a lack of fundamental understanding of such diverse interfaces. In addition, experimental techniques generally have practical objectives, such as the achievement of sufficient strength to sustain mechanical or thermal effects and/or have the proper electronic properties. In addition, the theoretical description of binding at interfaces is quite limited, and a proper data base for such theoretical analysis does not exist. This presentation will review both experimental and theoretical aspects of adhesion in nonpolymer materials. The objective will be to delineate the critical parameters needed, governing adhesion testing along with an outline of testing objectives. A distinction will be made between practical and fundamental objectives. Examples are given where interfacial bonding may govern experimental consideration. The present status of theory is presented along with recommendations for future progress and needs.

  15. Interfacial adhesion: Theory and experiment

    NASA Technical Reports Server (NTRS)

    Ferrante, John; Bozzolo, Guillermo H.; Finley, Clarence W.; Banerjea, Amitava

    1988-01-01

    Adhesion, the binding of different materials at an interface, is of general interest to many branches of technology, e.g., microelectronics, tribology, manufacturing, construction, etc. However, there is a lack of fundamental understanding of such diverse interfaces. In addition, experimental techniques generally have practical objectives, such as the achievement of sufficient strength to sustain mechanical or thermal effects and/or have the proper electronic properties. In addition, the theoretical description of binding at interfaces is quite limited, and a proper data base for such theoretical analysis does not exist. This presentation will review both experimental and theoretical aspects of adhesion in nonpolymer materials. The objective will be to delineate the critical parameters needed, governing adhesion testing along with an outline of testing objectives. A distinction will be made between practical and fundamental objectives. Examples are given where interfacial bonding may govern experimental consideration. The present status of theory is presented along wiith recommendations for future progress and needs.

  16. Adhesive arachnoiditis following lumbar myelography.

    PubMed

    Skalpe, I O

    1978-03-01

    Late sequelae (adhesive arachnoiditis) have been reported following myelography with the oily contrast medium (Pantopaque) and with the ionic water-soluble contrast media methiodal sodium (Abrodil, Conturex, Kontrast U) meglumine iothalamate (Conray Meglumine) and meglumine iocarmate (Bis-Conray, Dimer-X). Adhesive arachnoiditis has not yet been reported after the use of the nonionic water-soluble contrast medium metrizamide (Amipaque). Thus, this is considered the contrast medium of choice for lumbar myelography. Using the recommended dose of 10 ml with an iodine concentration of 170 mg/ml for this examination, adhesive arachnoiditis is unlikely to occur. Increased osmolality of spinal fluid after injection of contrast medium is related to increased frequency of arachnoiditis.

  17. Mechanics of Nascent Cell Adhesions

    NASA Astrophysics Data System (ADS)

    Mejean, Cecile O.; Schaefer, Andrew W.; Forscher, Paul; Dufresne, Eric R.

    2009-03-01

    Cells have the ability to sense and respond to mechanical and biochemical cues from their environment. In neurons, the binding and restraint of transmembrane cell adhesion molecules (CAMs) can trigger acute periods of axon growth. Preceding growth, the cell must create a stiff mechanical linkage between the CAM and the cytoskeleton. Using holographic optical tweezers, we manipulate CAM-coated beads on the membrane of the cell. We investigate the dynamics of the mechanical properties of this linkage as a function of time, applied force, and CAM density. We find that CAM-coated beads exhibit stochastic intermittent binding to the cytoskeleton. In time, we observed that the adhesions stiffen and their mechanical properties depend on the applied force. Treatment of cells with small molecules that alter cytoskeletal dynamics are used to probe the roles of actin filament assembly and myosin motor activity in adhesion formation.

  18. Adhesive, elastomeric gel impregnating composition

    DOEpatents

    Shaw, David Glenn; Pollard, John Randolph; Brooks, Robert Aubrey

    2002-01-01

    An improved capacitor roll with alternating film and foil layers is impregnated with an adhesive, elastomeric gel composition. The gel composition is a blend of a plasticizer, a polyol, a maleic anhydride that reacts with the polyol to form a polyester, and a catalyst for the reaction. The impregnant composition is introduced to the film and foil layers while still in a liquid form and then pressure is applied to aid with impregnation. The impregnant composition is cured to form the adhesive, elastomeric gel. Pressure is maintained during curing.

  19. Dual-Mode Adhesive Pad

    NASA Technical Reports Server (NTRS)

    Hartz, Leslie

    1994-01-01

    Tool helps worker grip and move along large, smooth structure with no handgrips or footholds. Adheres to surface but easily released by actuating simple mechanism. Includes handle and segmented contact-adhesive pad. Bulk of pad made of soft plastic foam conforming to surface of structure. Each segment reinforced with rib. In sticking mode, ribs braced by side catches. In peeling mode, side catches retracted, and segmented adhesive pad loses its stiffness. Modified versions useful in inspecting hulls of ships and scaling walls in rescue operations.

  20. Photoresist substrate having robust adhesion

    DOEpatents

    Dentinger, Paul M.

    2005-07-26

    A substrate material for LIGA applications w hose general composition is Ti/Cu/Ti/SiO.sub.2. The SiO.sub.2 is preferably applied to the Ti/Cu/Ti wafer as a sputtered coating, typically about 100 nm thick. This substrate composition provides improved adhesion for epoxy-based photoresist materials, and particularly the photoresist material SU-8.

  1. Fluorescence Reveals Contamination From Adhesives

    NASA Technical Reports Server (NTRS)

    Nikolia, William

    1992-01-01

    Contamination of nearby surfaces from ingredients in some adhesive materials detected by ultraviolet illumination and observation of resulting fluorescence. Identification of contaminants via telltale fluorescence not new; rather, significance lies in method of implementation and potential extension to wider variety of materials and applications.

  2. Shelf Stable Epoxy Repair Adhesive

    DTIC Science & Technology

    2015-02-01

    Epoxy Resin Adhesive WP-1763 viii FINAL REPORT List of Acronyms ACN Acetonitrile ASTM American Society for Testing and Materials BPA Bisphenol...the oven and immediately cooled to room temperature. Approximately 1.0 mL of acetonitrile ( ACN ) was added to each vial using a glass syringe. The

  3. Computational Chemistry of Adhesive Bonds

    NASA Technical Reports Server (NTRS)

    Phillips, Donald H.

    1999-01-01

    This investigation is intended to determine the electrical mechanical, and chemical properties of adhesive bonds at the molecular level. The initial determinations will be followed by investigations of the effects of environmental effects on the chemistry and properties of the bond layer.

  4. Nucleation and Growth of Integrin Adhesions

    PubMed Central

    Atilgan, Erdinç; Ovryn, Ben

    2009-01-01

    We present a model that provides a mechanistic understanding of the processes that govern the formation of the earliest integrin adhesions ex novo from an approximately planar plasma membrane. Using an analytic analysis of the free energy of a dynamically deformable membrane containing freely diffusing receptors molecules and long repeller molecules that inhibit integrins from binding with ligands on the extracellular matrix, we predict that a coalescence of polymerizing actin filaments can deform the membrane toward the extracellular matrix and facilitate integrin binding. Monte Carlo simulations of this system show that thermally induced membrane fluctuations can either zip-up and increase the radius of a nucleated adhesion or unzip and shrink an adhesion, but the fluctuations cannot bend the ventral membrane to nucleate an adhesion. To distinguish this integrin adhesion from more mature adhesions, we refer to this early adhesion as a nouveau adhesion. PMID:19413961

  5. Tape-Smoothing Tool For Adhesion Tests

    NASA Technical Reports Server (NTRS)

    Allen, Peter B.

    1992-01-01

    Small tool smoothes adhesive tape uniformly to ensure consistency and repeatability of tape-peel tests of adhesion of paint to substrate. Includes resilient pad covered with tough, smooth fabric. Internal spring regulates force applied to tape.

  6. Tackifier Dispersions to Make Pressure Sensitive Adhesives

    SciTech Connect

    2003-02-01

    Development of new processes for tackifier dispersion could improve the production of pressure sensitive adhesives. Pressure sensitive adhesives (PSAs) have the ability to adhere to different surfaces with manual or finger pressure.

  7. Microfluidic adhesion induced by subsurface microstructures.

    PubMed

    Majumder, Abhijit; Ghatak, Animangsu; Sharma, Ashutosh

    2007-10-12

    Natural adhesives in the feet of different arthropods and vertebrates show strong adhesion as well as excellent reusability. Whereas the hierarchical structures on the surface are known to have a substantial effect on adhesion, the role of subsurface structures such as the network of microchannels has not been studied. Inspired by these bioadhesives, we generated elastomeric layers with embedded air- or oil-filled microchannels. These adhesives showed remarkable enhancement of adhesion ( approximately 30 times), which results from the crack-arresting properties of the microchannels, together with the surface stresses caused by the capillary force. The importance of the thickness of the adhesive layer, channel diameter, interchannel spacing, and vertical position within the adhesive has been examined for developing an optimal design of this microfluidic adhesive.

  8. Adhesion of Antireflective Coatings in Multijunction Photovoltaics

    SciTech Connect

    Brock, Ryan; Miller, David C.; Dauskardt, Reinhold H.

    2016-11-21

    The development of a new composite dual cantilever beam (cDCB) thin-film adhesion testing method is reported, which allows the measurement of adhesion on the fragile thin substrates used in multijunction photovoltaics. We address the adhesion of several antireflective coating systems on multijunction cells. By varying interface chemistry and morphology, we demonstrate the ensuing effects on adhesion and help to develop an understanding of how high adhesion can be achieved, as adhesion values ranging from 0.5 J/m2 to 10 J/m2 were measured. Damp Heat (85 degrees C/85% RH) was used to invoke degradation of interfacial adhesion. We show that even with germanium substrates that fracture easily, quantitative measurements of adhesion can still be made at high test yield. The cDCB test is discussed as an important new methodology, which can be broadly applied to any system that makes use of thin, brittle, or otherwise fragile substrates.

  9. Transverse Reinforcement of Adhesive Joints

    NASA Astrophysics Data System (ADS)

    Sapozhnikov, S.; Shakirov, A.

    2015-05-01

    The shear of single-lap adhesive joints causes significant peel stresses in the adhesive layer, which is a particularly urgent problem for low-modulus polyurethane compositions. An experimental and computational analysis of various methods for increasing the load-bearing capacity of the joints by their strengthening with metallic z-elements was carried out. This strengthening hinders their delamination by the action of peel stresses, which allows one to reduce the overall dimensions and weight of adhesive joints. Two main strengthening methods were considered: with steel tapping screws (of diameter 2.5 mm) and blind aluminum rivets (of diameter 4.0 mm). The peculiarity of the strengthening lies in the fact that z-elements of minimum available diameter were used for reducing the effect of stress concentrations on the strength of the joints. The test of specimens for each type of strengthening showed an average increase in the ultimate load by 40% for the threaded reinforcements and by 10% for the rivets. During an analysis of stress state of the joints by the FEM, the nonlinear behavior of constituent materials and stress concentration in the region of reinforcing elements were taken into account. The mechanical properties of the adhesive layer and the GFRP covering were determined in separate experiments. The analysis showed that the weight of the reinforced adhesive joints could be lowered by 20-25% relative to that of unreinforced ones without reducing their load-bearing capacity. An additional effect caused by using the threaded reinforcing elements was a more than threefold increase in their rigidity as compared with that of analogous nonreinforced ones.

  10. Self-Adjustable Adhesion of Polyampholyte Hydrogels.

    PubMed

    Roy, Chanchal Kumar; Guo, Hong Lei; Sun, Tao Lin; Ihsan, Abu Bin; Kurokawa, Takayuki; Takahata, Masakazu; Nonoyama, Takayuki; Nakajima, Tasuku; Gong, Jian Ping

    2015-12-02

    Developing nonspecific, fast, and strong adhesives that can glue hydrogels and biotissues substantially promotes the application of hydrogels as biomaterials. Inspired by the ubiquitous adhesiveness of bacteria, it is reported that neutral polyampholyte hydrogels, through their self-adjustable surface, can show rapid, strong, and reversible adhesion to charged hydrogels and biological tissues through the Coulombic interaction.

  11. Current dental adhesives systems. A narrative review.

    PubMed

    Milia, Egle; Cumbo, Enzo; Cardoso, Rielson Jose A; Gallina, Giuseppe

    2012-01-01

    Adhesive dentistry is based on the development of materials which establish an effective bond with the tooth tissues. In this context, adhesive systems have attracted considerable research interest in recent years. Successful adhesive bonding depends on the chemistry of the adhesive, on appropriate clinical handling of the material as well as on the knowledge of the morphological changes caused on dental tissue by different bonding procedures. This paper outlines the status of contemporary adhesive systems, with particular emphasis on chemical characteristics and mode of interaction of the adhesives with enamel and dentinal tissues. Dental adhesives are used for several clinical applications and they can be classified based on the clinical regimen in "etch-and-rinse adhesives" and "self-etch adhesives". Other important considerations concern the different anatomical characteristics of enamel and dentine which are involved in the bonding procedures that have also implications for the technique used as well as for the quality of the bond. Etch-and-rinse adhesive systems generally perform better on enamel than self-etching systems which may be more suitable for bonding to dentine. In order to avoid a possible loss of the restoration, secondary caries or pulp damage due to bacteria penetration or due to cytotoxicity effects of eluted adhesive components, careful consideration of several factors is essential in selecting the suitable bonding procedure and adhesive system for the individual patient situation.

  12. 21 CFR 878.4010 - Tissue adhesive.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... adhesive for the topical approximation of skin—(1) Identification. A tissue adhesive for the topical approximation of skin is a device intended for topical closure of surgical incisions, including laparoscopic incisions, and simple traumatic lacerations that have easily approximated skin edges. Tissue adhesives...

  13. Nonwoven glass fiber mat reinforces polyurethane adhesive

    NASA Technical Reports Server (NTRS)

    Roseland, L. M.

    1967-01-01

    Nonwoven glass fiber mat reinforces the adhesive properties of a polyurethane adhesive that fastens hardware to exterior surfaces of aluminum tanks. The mat is embedded in the uncured adhesive. It ensures good control of the bond line and increases the peel strength.

  14. Influence of substrate modulus on gecko adhesion

    PubMed Central

    Klittich, Mena R.; Wilson, Michael C.; Bernard, Craig; Rodrigo, Rochelle M.; Keith, Austin J.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2017-01-01

    The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system’s performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics). PMID:28287647

  15. Influence of substrate modulus on gecko adhesion

    NASA Astrophysics Data System (ADS)

    Klittich, Mena R.; Wilson, Michael C.; Bernard, Craig; Rodrigo, Rochelle M.; Keith, Austin J.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2017-03-01

    The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system’s performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics).

  16. Bio-inspired adhesion: local chemical environments impact adhesive stability

    NASA Astrophysics Data System (ADS)

    Gebbie, Matthew A.; Rapp, Michael V.; Yu, Jing; Wei, Wei; Waite, J. Herbert; Israelachvili, Jacob N.

    2014-03-01

    3,4-dihydroxyphenylalanine (Dopa) is an amino acid that is naturally synthesized by marine mussels and exhibits the unique ability to strongly bind to surfaces in aqueous environments. However, the Dopa functional group undergoes auto-oxidation to a non-adhesive quinone form in neutral to basic pH conditions, limiting the utilization of Dopa in biomedical applications. In this work, we performed direct surface force measurements with in situ electrochemical control across a Dopa-rich native mussel foot protein (mfp-5), as well as three simplified model peptide sequences. We find that the neighboring peptide residues can significantly impact the redox stability of Dopa functional groups, with lysine residues imparting a substantial degree of Dopa redox stabilization. Surprisingly, the local chemical environments only minimally impact the magnitude of the adhesion forces measured between molecularly-smooth mica and gold surfaces. Our results provide molecular level insight into approaches that can be used to mitigate the detrimental impact of Dopa auto-oxidation, thus suggesting new molecular design strategies for improving the performance of Dopa-based underwater adhesives.

  17. A review of high-temperature adhesives

    NASA Technical Reports Server (NTRS)

    St.clair, A. K.; St.clair, T. L.

    1981-01-01

    The development of high temperature adhesives and polyphenylquinoxalines (PPQ) is reported. Thermoplastic polyimides and linear PPQ adhesive are shown to have potential for bonding both metals and composite structures. A nadic terminated addition polyimide adhesive, LARC-13, and an acetylene terminated phenylquinoxaline (ATPQ) were developed. Both of the addition type adhesives are shown to be more readily processable than linear materials but less thermooxidatively stable and more brittle. It is found that the addition type adhesives are able to perform, at elevated temperatures up to 595 C where linear systems fail thermoplastically.

  18. Ocular surface sealants and adhesives.

    PubMed

    Bhatia, Subir Singh

    2006-07-01

    Tissue adhesives, both synthetic and biologic, have a long history of use in ophthalmology. Cyanoacrylate-based glues have traditionally been the most widely used glues for various purposes. They have been specially useful for treating corneal perforations and have had significantly improved long-term outcomes. More recently, fibrin-based glues have gained a major role as a suture substitute for attaching biologic tissues and as surface sealants. The literature supports expanded use of fibrin glue in this fashion. Other new agents, such as polyethyelene glycols, have been underutilized and hold promise, especially as surface protectants. Numerous other glues are being developed and show promise as ocular surface sealants and protective membranes. Advances in knowledge about tissue adhesives are leading to more effective and efficient ophthalmic care.

  19. Particle adhesion in powder coating

    SciTech Connect

    Mazumder, M.K.; Wankum, D.L.; Knutson, M.; Williams, S.; Banerjee, S.

    1996-12-31

    Electrostatic powder coating is a widely used industrial painting process. It has three major advantages: (1) it provides high quality durable finish, (2) the process is environmentally friendly and does not require the use of organic solvents, and (3) it is economically competitive. The adhesion of electrostatically deposited polymer paint particles on the grounded conducting substrate depends upon many parameters: (a) particle size and shape distributions, (b) electrostatic charge distributions, (c) electrical resistivity, (d) dielectric strength of the particles, (e) thickness of the powder film, (f) presence and severity of the back corona, and (g) the conductivity and surface properties of the substrate. The authors present a model on the forces of deposition and adhesion of corona charged particles on conducting substrates.

  20. Acetylene-terminated polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Hanky, A. O.

    1983-01-01

    The nadic-encapped LARC-13 addition polyimide exhibits excellent flow, is easy to process, and can be utilized for short terms at temperatures up to 593 C. It retains good lap shear strength as an adhesive for titanium after aging in air up to 125 hours at 316 C; but lap shear strength degrades with longer exposures at that temperature. Thermid 600, an addition polyimide that is acetylene encapped, exhibits thermomechanical properties even after long term exposure in at air at 316 C. An inherent drawback of this system is that it has a narrow processing window. An acetylene encapped, addition polyimide which is a hybrid of these two systems was developed. It has good retention of strength after long term aging and is easily processed. The synthesis and characterization of various molecular weight oligomers of this system are discussed as well as the bonding, aging, and testing of lap shear adhesive samples.

  1. Dental adhesion: mechanism, techniques and durability.

    PubMed

    Manuja, N; Nagpal, R; Pandit, I K

    2012-01-01

    Contemporary dental adhesives show favorable immediate results in terms of bonding effectiveness. However, the durability of resin-dentin bonds is their major problem. It appears that simplification of adhesive techniques is rather detrimental to the long-term stability of resin-tooth interface. The hydrostatic pulpal pressure, the dentinal fluid flow and the increased dentinal wetness in vital dentin can affect the intimate interaction of certain dentin adhesives with dentinal tissue. Bond degradation occurs via water sorption, hydrolysis of ester linkages of methacrylate resins, and activation of endogenous dentin matrix metalloproteinases. The three-step etch-and-rinse adhesives still remain the gold standard in terms of durability. This review discusses the fundamental process of adhesion to enamel and dentin with different adhesive techniques, factors affecting the long-term bonding performance of modern adhesives and addresses the current perspectives for improving bond durability.

  2. High-Frequency Mechanostimulation of Cell Adhesion.

    PubMed

    Kadem, Laith F; Suana, K Grace; Holz, Michelle; Wang, Wei; Westerhaus, Hannes; Herges, Rainer; Selhuber-Unkel, Christine

    2017-01-02

    Cell adhesion is regulated by molecularly defined protein interactions and by mechanical forces, which can activate a dynamic restructuring of adhesion sites. Previous attempts to explore the response of cell adhesion to forces have been limited to applying mechanical stimuli that involve the cytoskeleton. In contrast, we here apply a new, oscillatory type of stimulus through push-pull azobenzenes. Push-pull azobenzenes perform a high-frequency, molecular oscillation upon irradiation with visible light that has frequently been applied in polymer surface relief grating. We here use these oscillations to address single adhesion receptors. The effect of molecular oscillatory forces on cell adhesion has been analyzed using single-cell force spectroscopy and gene expression studies. Our experiments demonstrate a reinforcement of cell adhesion as well as upregulated expression levels of adhesion-associated genes as a result of the nanoscale "tickling" of integrins. This novel type of mechanical stimulus provides a previously unprecedented molecular control of cellular mechanosensing.

  3. Theory of adhesion: role of surface roughness.

    PubMed

    Persson, B N J; Scaraggi, M

    2014-09-28

    We discuss how surface roughness influences the adhesion between elastic solids. We introduce a Tabor number which depends on the length scale or magnification, and which gives information about the nature of the adhesion at different length scales. We consider two limiting cases relevant for (a) elastically hard solids with weak (or long ranged) adhesive interaction (DMT-limit) and (b) elastically soft solids with strong (or short ranged) adhesive interaction (JKR-limit). For the former cases we study the nature of the adhesion using different adhesive force laws (F ∼ u(-n), n = 1.5-4, where u is the wall-wall separation). In general, adhesion may switch from DMT-like at short length scales to JKR-like at large (macroscopic) length scale. We compare the theory predictions to results of exact numerical simulations and find good agreement between theory and simulation results.

  4. Theory of adhesion: Role of surface roughness

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.; Scaraggi, M.

    2014-09-01

    We discuss how surface roughness influences the adhesion between elastic solids. We introduce a Tabor number which depends on the length scale or magnification, and which gives information about the nature of the adhesion at different length scales. We consider two limiting cases relevant for (a) elastically hard solids with weak (or long ranged) adhesive interaction (DMT-limit) and (b) elastically soft solids with strong (or short ranged) adhesive interaction (JKR-limit). For the former cases we study the nature of the adhesion using different adhesive force laws (F ˜ u-n, n = 1.5-4, where u is the wall-wall separation). In general, adhesion may switch from DMT-like at short length scales to JKR-like at large (macroscopic) length scale. We compare the theory predictions to results of exact numerical simulations and find good agreement between theory and simulation results.

  5. Adhesive mechanisms in cephalopods: a review.

    PubMed

    von Byern, Janek; Klepal, Waltraud

    2006-01-01

    Several genera of cephalopods (Nautilus, Sepia, Euprymna and Idiosepius) produce adhesive secretions, which are used for attachment to the substratum, for mating and to capture prey. These adhesive structures are located in different parts of the body, viz. in the digital tentacles (Nautilus), in the ventral surface of the mantle and fourth arm pair (Sepia), in the dorsal epidermis (Euprymna), or in the dorsal mantle side and partly on the fins (Idiosepius). Adhesion in Sepia is induced by suction of dermal structures on the mantle, while for Nautilus, Euprymna and Idiosepius adhesion is probably achieved by chemical substances. Histochemical studies indicate that in Nautilus and Idiosepius secretory cells that appear to be involved in adhesion stain for carbohydrates and protein, whilst in Euprymna only carbohydrates are detectable. De-adhesion is either achieved by muscle contraction of the tentacles and mantle (Nautilus and Sepia) or by secretion of substances (Euprymna). The de-adhesive mechanism used by Idiosepius remains unknown.

  6. Adhesion effects in contact interaction of solids

    NASA Astrophysics Data System (ADS)

    Goryacheva, Irina; Makhovskaya, Yulya

    2008-01-01

    An approach to solving problems of the interaction of axisymmetric elastic bodies in the presence of adhesion is developed. The different natures of adhesion, i.e. capillary adhesion, or molecular adhesion described by the Lennard-Jones potential are examined. The effect of additional loading of the interacting bodies outside the contact zone is also investigated. The approach is based on the representation of the pressure outside the contact zone arising from adhesion by a step function. The analytical solution is obtained and is used to analyze the influence of the form of the adhesion interaction potential, of the surface energy of interacting bodies or the films covering the bodies, their shapes (parabolic, higher power exponential function), volume of liquid in the meniscus, density of contact spots, of elastic modulus and the Poisson ratio on the characteristics of the interaction of the bodies in the presence of adhesion. To cite this article: I. Goryacheva, Y. Makhovskaya, C. R. Mecanique 336 (2008).

  7. Polymer Claw: Instant Underwater Adhesive

    DTIC Science & Technology

    2012-03-23

    technology is the use of pressure sensitive microcapsules , which release reactive amine crosslinkers into an adhesive putty when pressed against the...PROIECT GOALS AND OBIECTIVES 2 2 KEY ACCOMPLISHMENTS 2 3.1 KICKOFF MEETING 3 3.2 AMINE MICROENCAPSULATION 3 3.3 CAUSTIC CLEANING AGENT 5 3.4...caustic, and the abrasive brush. We successfully synthesized amine-filled microcapsules and a dry mixture of caustic ingredients that only activate when

  8. Polymer Nanocarriers for Dentin Adhesion

    PubMed Central

    Osorio, R.; Osorio, E.; Medina-Castillo, A.L.; Toledano, M.

    2014-01-01

    To obtain more durable adhesion to dentin, and to protect collagen fibrils of the dentin matrix from degradation, calcium- and phosphate-releasing particles have been incorporated into the dental adhesive procedure. The aim of the present study was to incorporate zinc-loaded polymeric nanocarriers into a dental adhesive system to facilitate inhibition of matrix metalloproteinases (MMPs)-mediated collagen degradation and to provide calcium ions for mineral deposition within the resin-dentin bonded interface. PolymP-nActive nanoparticles (nanoMyP) were zinc-loaded through 30-minute ZnCl2 immersion and tested for bioactivity by means of 7 days’ immersion in simulated body fluid solution (the Kokubo test). Zinc-loading and calcium phosphate depositions were examined by scanning and transmission electron microscopy, elemental analysis, and x-ray diffraction. Nanoparticles in ethanol solution infiltrated into phosphoric-acid-etched human dentin and Single Bond (3M/ESPE) were applied to determine whether the nanoparticles interfered with bonding. Debonded sticks were analyzed by scanning electron microscopy. A metalloproteinase collagen degradation assay was also performed in resin-infiltrated dentin with and without nanoparticles, measuring C-terminal telopeptide of type I collagen (ICTP) concentration in supernatants, after 4 wk of immersion in artificial saliva. Numerical data were analyzed by analysis of variance (ANOVA) and Student-Newman-Keuls multiple comparisons tests (p < .05). Nanoparticles were effectively zinc-loaded and were shown to have a chelating effect, retaining calcium regardless of zinc incorporation. Nanoparticles failed to infiltrate demineralized intertubular dentin and remained on top of the hybrid layer, without altering bond strength. Calcium and phosphorus were found covering nanoparticles at the hybrid layer, after 24 h. Nanoparticle application in etched dentin also reduced MMP-mediated collagen degradation. Tested nanoparticles may be

  9. Polymer nanocarriers for dentin adhesion.

    PubMed

    Osorio, R; Osorio, E; Medina-Castillo, A L; Toledano, M

    2014-12-01

    To obtain more durable adhesion to dentin, and to protect collagen fibrils of the dentin matrix from degradation, calcium- and phosphate-releasing particles have been incorporated into the dental adhesive procedure. The aim of the present study was to incorporate zinc-loaded polymeric nanocarriers into a dental adhesive system to facilitate inhibition of matrix metalloproteinases (MMPs)-mediated collagen degradation and to provide calcium ions for mineral deposition within the resin-dentin bonded interface. PolymP- N : Active nanoparticles (nanoMyP) were zinc-loaded through 30-minute ZnCl2 immersion and tested for bioactivity by means of 7 days' immersion in simulated body fluid solution (the Kokubo test). Zinc-loading and calcium phosphate depositions were examined by scanning and transmission electron microscopy, elemental analysis, and x-ray diffraction. Nanoparticles in ethanol solution infiltrated into phosphoric-acid-etched human dentin and Single Bond (3M/ESPE) were applied to determine whether the nanoparticles interfered with bonding. Debonded sticks were analyzed by scanning electron microscopy. A metalloproteinase collagen degradation assay was also performed in resin-infiltrated dentin with and without nanoparticles, measuring C-terminal telopeptide of type I collagen (ICTP) concentration in supernatants, after 4 wk of immersion in artificial saliva. Numerical data were analyzed by analysis of variance (ANOVA) and Student-Newman-Keuls multiple comparisons tests (p < .05). Nanoparticles were effectively zinc-loaded and were shown to have a chelating effect, retaining calcium regardless of zinc incorporation. Nanoparticles failed to infiltrate demineralized intertubular dentin and remained on top of the hybrid layer, without altering bond strength. Calcium and phosphorus were found covering nanoparticles at the hybrid layer, after 24 h. Nanoparticle application in etched dentin also reduced MMP-mediated collagen degradation. Tested nanoparticles may be

  10. Modeling of Sylgard Adhesive Strength

    SciTech Connect

    Stevens, Ralph Robert

    2015-02-03

    Sylgard is the name of a silicone elastomeric potting material manufactured by Dow Corning Corporation.1 Although the manufacturer cites its low adhesive strength as a feature of this product, thin layers of Sylgard do in fact have a non-negligible strength, which has been measured in recent tensile and shear debonding tests. The adhesive strength of thin layers of Sylgard potting material can be important in applications in which components having signi cantly di erent thermal expansion properties are potted together, and the potted assembly is subjected to temperature changes. The tensile and shear tractions developed on the potted surfaces of the components can cause signi cant internal stresses, particularly for components made of low-strength materials with a high area-to-volume ratio. This report is organized as follows: recent Sylgard debonding tests are rst brie y summarized, with particular attention to the adhesion between Sylgard and PBX 9501, and also between Sylgard and aluminum. Next, the type of numerical model that will be used to simulate the debonding behavior exhibited in these tests is described. Then the calibration of the debonding model will be illustrated. Finally, the method by which the model parameters are adjusted (scaled) to be applicable to other, non- tested bond thicknesses is summarized, and all parameters of the model (scaled and unscaled) are presented so that other investigators can reproduce all of the simulations described in this report as well as simulations of the application of interest.

  11. Culinary Medicine-Jalebi Adhesions.

    PubMed

    Kapoor, Vinay K

    2016-02-01

    Culinary terms have been used to describe anatomy (bean-shaped kidneys), pathology (strawberry gall bladder), clinical signs (café-au-lait spots), radiological images (sausage-shaped pancreas), etc. While Indian cuisine is popular all over the world, no Indian dish finds mention in medical terminology. In intra-abdominal adhesions, sometimes, the intestinal loops are so densely adherent that it is difficult to make out proximal from distal and it is impossible to separate them without injuring the bowel resulting in spill of contents-resection is the only option (Fig. 1). Jalebi, an Indian dessert, has a single long tubular strip of fried batter filled with sugary syrup so intertwined that it is impossible to discern its ends; if broken, the syrup spills out-the best way to relish it is to chew the whole piece (Fig. 2). Because of these similarities between them, I propose to name dense intra-abdominal adhesions as 'jalebi adhesions.'

  12. A review of our development of dental adhesives--effects of radical polymerization initiators and adhesive monomers on adhesion.

    PubMed

    Ikemura, Kunio; Endo, Takeshi

    2010-03-01

    This paper reviews the development of dental adhesives by collating information of related studies from original scientific papers, reviews, and patent literatures. Through our development, novel radical polymerization initiators, adhesive monomers, and microcapsules were synthesized, and their effects on adhesion were investigated. It was found that 5-monosubstituted barbituric acid (5-MSBA)-containing ternary initiators in conjunction with adhesive monomers contributed to effective adhesion with good polymerization reactivity. Several kinds of novel adhesive monomers bearing carboxyl group, phosphonic acid group or sulfur-containing group were synthesized, and investigated their multi-purpose bonding functions. It was suggested that the flexible methylene chain in the structure of adhesive monomers played a pivotal role in their enhanced bonding durability. It was found that the combination of acidic monomers with sulfur-containing monomer markedly improved adhesion to enamel, dentin, porcelain, alumina, zirconia, non-precious metals and precious metals. A new poly(methyl methacrylate) (PMMA)-type adhesive resin comprising microencapsulated polymerization initiators was also found to exhibit both good formulation stability and excellent adhesive property.

  13. Chitosan Adhesive Films for Photochemical Tissue Bonding

    NASA Astrophysics Data System (ADS)

    Lauto, Antonio; Mawad, Damia; Barton, Matthew; Piller, Sabine C.; Longo, Leonardo

    2011-08-01

    Photochemical tissue bonding (PTB) is a promising sutureless technique for tissue repair. PTB is often achieved by applying a solution of rose bengal (RB) between two tissue edges, which are irradiated by a green laser to crosslink collagen fibers with minimal heat production. In this study, RB has been incorporated in chitosan films to create a novel tissue adhesive that is laser-activated. Materials and Methods. Adhesive films, based on chitosan and containing ˜0.1wt% RB were manufactured and bonded to calf intestine by a solid state laser (wavelength = 532 nm, Fluence ˜110 J/cm2, spot size ˜5 mm). A single-column tensiometer, interfaced with a personal computer, tested the bonding strength. K-type thermocouples recorded the temperature (T) at the adhesive-tissue interface during laser irradiation. Human fibroblasts were also seeded on the adhesive and cultured for 48 hours to assess cell growth. Results and Conclusion. The RB-chitosan adhesive bonded firmly to the intestine (15±2 kPa, n = 31). The adhesion strength dropped to 0.5±0.1 kPa (n = 8) when the laser was not applied to the adhesive. The average temperature of the adhesive increased from 26 °C to 32 °C during laser exposure. Fibroblasts grew confluent on the adhesive without morphological changes. A new biocompatible chitosan adhesive has been developed that bonds photochemically to tissue with minimal temperature increase.

  14. Sundew adhesive: a naturally occurring hydrogel

    PubMed Central

    Huang, Yujian; Wang, Yongzhong; Sun, Leming; Agrawal, Richa; Zhang, Mingjun

    2015-01-01

    Bioadhesives have drawn increasing interest in recent years, owing to their eco-friendly, biocompatible and biodegradable nature. As a typical bioadhesive, sticky exudate observed on the stalked glands of sundew plants aids in the capture of insects and this viscoelastic adhesive has triggered extensive interests in revealing the implied adhesion mechanisms. Despite the significant progress that has been made, the structural traits of the sundew adhesive, especially the morphological characteristics in nanoscale, which may give rise to the viscous and elastic properties of this mucilage, remain unclear. Here, we show that the sundew adhesive is a naturally occurring hydrogel, consisting of nano-network architectures assembled with polysaccharides. The assembly process of the polysaccharides in this hydrogel is proposed to be driven by electrostatic interactions mediated with divalent cations. Negatively charged nanoparticles, with an average diameter of 231.9 ± 14.8 nm, are also obtained from this hydrogel and these nanoparticles are presumed to exert vital roles in the assembly of the nano-networks. Further characterization via atomic force microscopy indicates that the stretching deformation of the sundew adhesive is associated with the flexibility of its fibrous architectures. It is also observed that the adhesion strength of the sundew adhesive is susceptible to low temperatures. Both elasticity and adhesion strength of the sundew adhesive reduce in response to lowering the ambient temperature. The feasibility of applying sundew adhesive for tissue engineering is subsequently explored in this study. Results show that the fibrous scaffolds obtained from sundew adhesive are capable of increasing the adhesion of multiple types of cells, including fibroblast cells and smooth muscle cells, a property that results from the enhanced adsorption of serum proteins. In addition, in light of the weak cytotoxic activity exhibited by these scaffolds towards a variety of

  15. Adhesion enhancement of biomimetic dry adhesives by nanoparticle in situ synthesis

    NASA Astrophysics Data System (ADS)

    Díaz Téllez, J. P.; Harirchian-Saei, S.; Li, Y.; Menon, C.

    2013-10-01

    A novel method to increase the adhesion strength of a gecko-inspired dry adhesive is presented. Gold nanoparticles are synthesized on the tips of the microfibrils of a polymeric dry adhesive to increase its Hamaker constant. Formation of the gold nanoparticles is qualitatively studied through a colour change in the originally transparent substance and quantitatively analysed using ultraviolet-visible spectrophotometry. A pull-off force test is employed to quantify the adhesion enhancement. Specifically, adhesion forces of samples with and without embedded gold nanoparticles are measured and compared. The experimental results indicate that an adhesion improvement of 135% can be achieved.

  16. Proteomic dataset of the sea urchin Paracentrotus lividus adhesive organs and secreted adhesive

    PubMed Central

    Lebesgue, Nicolas; da Costa, Gonçalo; Ribeiro, Raquel Mesquita; Ribeiro-Silva, Cristina; Martins, Gabriel G.; Matranga, Valeria; Scholten, Arjen; Cordeiro, Carlos; Heck, Albert J.R.; Santos, Romana

    2016-01-01

    Sea urchins have specialized adhesive organs called tube feet, which mediate strong but reversible adhesion. Tube feet are composed by a disc, producing adhesive and de-adhesive secretions for substratum attachment, and a stem for movement. After detachment the secreted adhesive remains bound to the substratum as a footprint. Recently, a label-free quantitative proteomic approach coupled with the latest mass-spectrometry technology was used to analyze the differential proteome of Paracentrotus lividus adhesive organ, comparing protein expression levels in the tube feet adhesive part (the disc) versus the non-adhesive part (the stem), and also to profile the proteome of the secreted adhesive (glue). This data article contains complementary figures and results related to the research article “Deciphering the molecular mechanisms underlying sea urchin reversible adhesion: a quantitative proteomics approach” (Lebesgue et al., 2016) [1]. Here we provide a dataset of 1384 non-redundant proteins, their fragmented peptides and expression levels, resultant from the analysis of the tube feet differential proteome. Of these, 163 highly over-expressed tube feet disc proteins (>3-fold), likely representing the most relevant proteins for sea urchin reversible adhesion, were further annotated in order to determine the potential functions. In addition, we provide a dataset of 611 non-redundant proteins identified in the secreted adhesive proteome, as well as their functional annotation and grouping in 5 major protein groups related with adhesive exocytosis, and microbial protection. This list was further analyzed to identify the most abundant protein groups and pinpoint putative adhesive proteins, such as Nectin, the most abundant adhesive protein in sea urchin glue. The obtained data uncover the key proteins involved in sea urchins reversible adhesion, representing a step forward to the development of new wet-effective bio-inspired adhesives. PMID:27182547

  17. Proteomic dataset of the sea urchin Paracentrotus lividus adhesive organs and secreted adhesive.

    PubMed

    Lebesgue, Nicolas; da Costa, Gonçalo; Ribeiro, Raquel Mesquita; Ribeiro-Silva, Cristina; Martins, Gabriel G; Matranga, Valeria; Scholten, Arjen; Cordeiro, Carlos; Heck, Albert J R; Santos, Romana

    2016-06-01

    Sea urchins have specialized adhesive organs called tube feet, which mediate strong but reversible adhesion. Tube feet are composed by a disc, producing adhesive and de-adhesive secretions for substratum attachment, and a stem for movement. After detachment the secreted adhesive remains bound to the substratum as a footprint. Recently, a label-free quantitative proteomic approach coupled with the latest mass-spectrometry technology was used to analyze the differential proteome of Paracentrotus lividus adhesive organ, comparing protein expression levels in the tube feet adhesive part (the disc) versus the non-adhesive part (the stem), and also to profile the proteome of the secreted adhesive (glue). This data article contains complementary figures and results related to the research article "Deciphering the molecular mechanisms underlying sea urchin reversible adhesion: a quantitative proteomics approach" (Lebesgue et al., 2016) [1]. Here we provide a dataset of 1384 non-redundant proteins, their fragmented peptides and expression levels, resultant from the analysis of the tube feet differential proteome. Of these, 163 highly over-expressed tube feet disc proteins (>3-fold), likely representing the most relevant proteins for sea urchin reversible adhesion, were further annotated in order to determine the potential functions. In addition, we provide a dataset of 611 non-redundant proteins identified in the secreted adhesive proteome, as well as their functional annotation and grouping in 5 major protein groups related with adhesive exocytosis, and microbial protection. This list was further analyzed to identify the most abundant protein groups and pinpoint putative adhesive proteins, such as Nectin, the most abundant adhesive protein in sea urchin glue. The obtained data uncover the key proteins involved in sea urchins reversible adhesion, representing a step forward to the development of new wet-effective bio-inspired adhesives.

  18. Synaptic Cell Adhesion Molecules in Alzheimer's Disease

    PubMed Central

    Leshchyns'ka, Iryna

    2016-01-01

    Alzheimer's disease (AD) is a neurodegenerative brain disorder associated with the loss of synapses between neurons in the brain. Synaptic cell adhesion molecules are cell surface glycoproteins which are expressed at the synaptic plasma membranes of neurons. These proteins play key roles in formation and maintenance of synapses and regulation of synaptic plasticity. Genetic studies and biochemical analysis of the human brain tissue, cerebrospinal fluid, and sera from AD patients indicate that levels and function of synaptic cell adhesion molecules are affected in AD. Synaptic cell adhesion molecules interact with Aβ, a peptide accumulating in AD brains, which affects their expression and synaptic localization. Synaptic cell adhesion molecules also regulate the production of Aβ via interaction with the key enzymes involved in Aβ formation. Aβ-dependent changes in synaptic adhesion affect the function and integrity of synapses suggesting that alterations in synaptic adhesion play key roles in the disruption of neuronal networks in AD. PMID:27242933

  19. Mussel-Inspired Adhesives and Coatings

    NASA Astrophysics Data System (ADS)

    Lee, Bruce P.; Messersmith, P. B.; Israelachvili, J. N.; Waite, J. H.

    2011-08-01

    Mussels attach to solid surfaces in the sea. Their adhesion must be rapid, strong, and tough, or else they will be dislodged and dashed to pieces by the next incoming wave. Given the dearth of synthetic adhesives for wet polar surfaces, much effort has been directed to characterizing and mimicking essential features of the adhesive chemistry practiced by mussels. Studies of these organisms have uncovered important adaptive strategies that help to circumvent the high dielectric and solvation properties of water that typically frustrate adhesion. In a chemical vein, the adhesive proteins of mussels are heavily decorated with Dopa, a catecholic functionality. Various synthetic polymers have been functionalized with catechols to provide diverse adhesive, sealant, coating, and anchoring properties, particularly for critical biomedical applications.

  20. Mussel-Inspired Adhesives and Coatings

    PubMed Central

    Lee, Bruce P.; Messersmith, P.B.; Israelachvili, J.N.; Waite, J.H.

    2011-01-01

    Mussels attach to solid surfaces in the sea. Their adhesion must be rapid, strong, and tough, or else they will be dislodged and dashed to pieces by the next incoming wave. Given the dearth of synthetic adhesives for wet polar surfaces, much effort has been directed to characterizing and mimicking essential features of the adhesive chemistry practiced by mussels. Studies of these organisms have uncovered important adaptive strategies that help to circumvent the high dielectric and solvation properties of water that typically frustrate adhesion. In a chemical vein, the adhesive proteins of mussels are heavily decorated with Dopa, a catecholic functionality. Various synthetic polymers have been functionalized with catechols to provide diverse adhesive, sealant, coating, and anchoring properties, particularly for critical biomedical applications. PMID:22058660

  1. Functionally Graded Adhesives for Composite Joints

    NASA Technical Reports Server (NTRS)

    Stapleton, Scott E.; Waas, Anthony M.; Arnold, Steven M.

    2012-01-01

    Adhesives with functionally graded material properties are being considered for use in adhesively bonded joints to reduce the peel stress concentrations located near adherend discontinuities. Several practical concerns impede the actual use of such adhesives. These include increased manufacturing complications, alterations to the grading due to adhesive flow during manufacturing, and whether changing the loading conditions significantly impact the effectiveness of the grading. An analytical study is conducted to address these three concerns. An enhanced joint finite element, which uses an analytical formulation to obtain exact shape functions, is used to model the joint. Furthermore, proof of concept testing is conducted to show the potential advantages of functionally graded adhesives. In this study, grading is achieved by strategically placing glass beads within the adhesive layer at different densities along the joint.

  2. Adhesion and wear resistance of materials

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1986-01-01

    Recent studies into the nature of bonding at the interface between two solids in contact or a solid and deposited film have provided a better understanding of those properties important to the adhesive wear resistance of materials. Analytical and experimental progress are reviewed. For simple metal systems the adhesive bond forces are related to electronic wave function overlap. With metals in contact with nonmetals, molecular-orbital energy, and density of states, respectively can provide insight into adhesion and wear. Experimental results are presented which correlate adhesive forces measured between solids and the electronic surface structures. Orientation, surface reconstruction, surface segregation, adsorption are all shown to influence adhesive interfacial strength. The interrelationship between adhesion and the wear of the various materials as well as the life of coatings applied to substrates are discussed. Metallic systems addressed include simple metals and alloys and these materials in contact with themselves, both oxide and nonoxide ceramics, diamond, polymers, and inorganic coating compounds, h as diamondlike carbon.

  3. Improved Cure-in-Place Silicone Adhesives

    NASA Technical Reports Server (NTRS)

    Blevins, C. E.; Sweet, J.; Gonzalez, R.

    1982-01-01

    Two improved cure-in-place silicone-elastomer-based adhesives have low thermal expansion and low thermal conductivity. Adhesives are flexible at low temperature and withstand high temperatures without disintegrating. New ablative compounds were initially developed for in-flight repair of insulating tile on Space Shuttle orbiter. Could find use in other applications requiring high-performance adhesives, such as sealants for solar collectors.

  4. Influence of composition on the adhesive strength and initial viscosity of denture adhesives.

    PubMed

    Han, Jian-min; Hong, Guang; Hayashida, Kentaro; Maeda, Takeshi; Murata, Hiroshi; Sasaki, Keiichi

    2014-01-01

    To investigate the effect of composition on the initial viscosity and adhesive strength between denture adhesives and the denture base. Two types of water-soluble polymers (methoxy ethylene maleic anhydride copolymer [PVM-MA] and sodium carboxymethyl cellulose [CMC]) were used. Samples were divided into three groups. Group 1 contained only PVM-MA; Group 2 contained only CMC; and Group 3 contained PVM-MA and CMC. The initial viscosity and adhesive strength were measured. For Group 1, the initial viscosity increased significantly as PVM-MA content increased. The adhesive strength of Group 1 lasted longer than Group 2. The adhesive strength of Group 3 varied greatly. The ratio of CMC and PVM-MA has a significant effect on the initial viscosity and adhesive strength of denture adhesives. Our results suggest that it is possible to improve the durability of a denture adhesive by combining different water-soluble polymers.

  5. The development of aerospace polyimide adhesives

    NASA Technical Reports Server (NTRS)

    St.clair, A. K.; St.clair, T. L.

    1983-01-01

    Few materials are available which can be used as aerospace adhesives at temperatures in the range of 300 C. The Materials Division at NASA-Langley Research Center developed several high temperature polyimide adhesives to fulfill the stringent needs of current aerospace programs. These adhesives are the result of a decade of basic research studies on the structure property relationships of both linear and addition aromatic polyimides. The development of both in house and commercially available polyimides is reviewed with regards to their potential for use as aerospace adhesives.

  6. The development of aerospace polyimide adhesives

    NASA Technical Reports Server (NTRS)

    St. Clair, A. K.; St. Clair, T. L.

    1984-01-01

    Few materials are available which can be used as aerospace adhesives at temperatures in the range of 300 C. The Materials Division at NASA-Langley Research Center developed several high temperature polyimide adhesives to fulfill the stringent needs of current aerospace programs. These adhesives are the result of a decade of basic research studies on the structure property relationships of both linear and addition aromatic polyimides. The development of both in house and commercially available polyimides is reviewed with regards to their potential for use as aerospace adhesives.

  7. Comparison of three work of adhesion measurements

    SciTech Connect

    Emerson, J.A.; O`Toole, E.; Zamora, D.; Poon, B.

    1998-02-01

    Practical work of adhesion measurements are being studied for several types of polymer/metal combinations in order to obtain a better understanding of the adhesive failure mechanisms for systems containing encapsulated and bonded components. The primary question is whether studies of model systems can be extended to systems of technological interest. The authors report on their first attempts to obtain the work of adhesion between a PDMS polymer and stainless steel. The work of adhesion measurements were made using three techniques -- contact angle, adhesive fracture energy at low deformation rates and JKR. Previous work by Whitesides` group show a good correlation between JKR and contact angle measurements for PDMS. Their initial work focused on duplicating the PDMS measurements of Chaudury. In addition, in this paper the authors extend the work of adhesion measurement to third technique -- interfacial failure energy. The ability to determine the reversible work of adhesion for practical adhesive joints allows understanding of several issues that control adhesion: surface preparation, nature of the interphase region, and bond durability.

  8. Investigation of package sealing using organic adhesives

    NASA Technical Reports Server (NTRS)

    Perkins, K. L.; Licari, J. J.

    1977-01-01

    A systematic study was performed to evaluate the suitability of adhesives for sealing hybrid packages. Selected adhesives were screened on the basis of their ability to seal gold-plated Kovar butterfly-type packages that retain their seal integrity after individual exposures to increasingly severe temperature-humidity environments. Tests were also run using thermal shock, temperature cycling, mechanical shock and temperature aging. The four best adhesives were determined and further tested in a 60 C/98% RH environment and continuously monitored in regard to moisture content. Results are given, however, none of the tested adhesives passed all the tests.

  9. Adhesive strength of autologous fibrin glue.

    PubMed

    Yoshida, H; Hirozane, K; Kamiya, A

    2000-03-01

    To establish an easy and rapid method for measuring the adhesive strength of fibrin glue and to clarify the factor(s) most affecting the strength, a study was made on the effect of the concentration of plasma components on the strength of cryoprecipitate (Cryo) prepared from a subject's own autologous plasma to be used as fibrin glue. The adhesive strength of the Cryo was measured with various supporting materials instead of animal skin using a tester of tension and compression. The results were as follows: (1) the strength of Cryo applied to ground flat glass (4 cm2) was significantly greater than that applied to clear glass, clear plastic, or smooth and flat wood chips; (2) the adhesive strength of Cryo depended on the concentration of thrombin with the optimal concentration being 50 units/ml; (3) the concentration of CaCl2 did not affect the adhesive strength of Cryo; (4) the adhesive reaction was dependent on the temperature and the adhesive strength more quickly reached a steady state at 37 degrees C than at lower temperature; (5) the adhesive strength was correlated well with the total concentration of fibrinogen and fibronectin. These results indicate that the adhesive strength of Cryo can be easily and quickly evaluated using a tester and ground glass with thrombin at 50 units/ml, and that the adhesive strength of Cryo can be predicted from the total concentration of fibrinogen and fibronectin.

  10. Acceptance Criteria for Aerospace Structural Adhesives.

    DTIC Science & Technology

    ADHESIVES, *AIRFRAMES, PRIMERS, STRUCTURAL ENGINEERING, CHEMICAL COMPOSITION, MECHANICAL PROPERTIES, INDUSTRIAL PRODUCTION , DATA ACQUISITION , PARTICLE SIZE, ACCEPTANCE TESTS, ELASTOMERS, BONDING, QUALITY CONTROL, .

  11. Effect of water absorption on pollen adhesion.

    PubMed

    Lin, Haisheng; Lizarraga, Leonardo; Bottomley, Lawrence A; Carson Meredith, J

    2015-03-15

    Pollens possess a thin liquid coating, pollenkitt, which plays a major role in adhesion by forming capillary menisci at interfaces. Unfortunately, the influence of humidity on pollenkitt properties and capillary adhesion is unknown. Because humidity varies widely in the environment, the answers have important implications for better understanding plant reproduction, allergy and asthma, and pollen as atmospheric condensation nuclei. Here, pollenkitt-mediated adhesion of sunflower pollen to hydrophilic and hydrophobic surfaces was measured as a function of humidity. The results quantify for the first time the significant water absorption of pollenkitt and the resulting complex dependence of adhesion on humidity. On hydrophilic Si, adhesion increased with increasing RH for pollens with or without pollenkitt, up to 200nN at 70% RH. In contrast, on hydrophobic PS, adhesion of pollenkitt-free pollen is independent of RH. Surprisingly, when pollenkitt was present adhesion forces on hydrophobic PS first increased with RH up to a maximum value at 35% RH (∼160nN), and then decreased with further increases in RH. Independent measurement of pollenkitt properties is used with models of capillary adhesion to show that humidity-dependent changes in pollenkitt wetting and viscosity are responsible for this complex adhesion behavior.

  12. Strength distributions of adhesive bonded and adhesive/rivet combined joints

    NASA Astrophysics Data System (ADS)

    Imanaka, Makoto; Haraga, Kosuke; Nishikawa, Tetsuya

    1992-11-01

    The tensile and shear strengths of adhesive and adhesive/rivet combined joints are statistically evaluated, and the probability of failure is calculated for these two types of joints. Attention is given to the effects of the adhesive/rivet combination on mean tensile shear strength and coefficient of variation. The adhesive joint's strength distribution was well approximated by Weibull or doubly-exponential distribution function; tensile shear strength is significantly improved by the combination with rivets.

  13. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Pressure-sensitive adhesives. 175.125 Section 175... Adhesives § 175.125 Pressure-sensitive adhesives. Pressure-sensitive adhesives may be safely used as the... prescribed conditions: (a) Pressure-sensitive adhesives prepared from one or a mixture of two or more of...

  14. Design and fabrication of polymer based dry adhesives inspired by the gecko adhesive system

    NASA Astrophysics Data System (ADS)

    Jin, Kejia

    There has been significant interest in developing dry adhesives mimicking the gecko adhesive system, which offers several advantages compared to conventional pressure sensitive adhesives. Specifically, gecko adhesive pads have anisotropic adhesion properties: the adhesive pads (spatulae) stick strongly when sheared in one direction but are non-adherent when sheared in the opposite direction. This anisotropy property is attributed to the complex topography of the array of fine tilted and curved columnar structures (setae) that bear the spatulae. In this thesis, easy, scalable methods, relying on conventional and unconventional techniques are presented to incorporate tilt in the fabrication of synthetic polymer-based dry adhesives mimicking the gecko adhesive system, which provide anisotropic adhesion properties. In the first part of the study, the anisotropic adhesion and friction properties of samples with various tilt angles to test the validity of a nanoscale tape-peeling model of spatular function are measured. Consistent with the Peel Zone model, samples with lower tilt angles yielded larger adhesion forces. Contact mechanics of the synthetic array were highly anisotropic, consistent with the frictional adhesion model and gecko-like. Based on the original design, a new design of gecko-like dry adhesives was developed which showed superior tribological properties and furthermore showed anisotropic adhesive properties without the need for tilt in the structures. These adhesives can be used to reversibly suspend weights from vertical surfaces (e.g., walls) and, for the first time to our knowledge, horizontal surfaces (e.g., ceilings) by simultaneously and judiciously activating anisotropic friction and adhesion forces. Furthermore, adhesion properties between artificial gecko-inspired dry adhesives and rough substrates with varying roughness are studied. The results suggest that both adhesion and friction forces on a rough substrate depends significantly on the

  15. Polyimide adhesives for titanium and composite bonding

    NASA Technical Reports Server (NTRS)

    St. Clair, A. K.; St. Clair, T. L.

    1978-01-01

    Approach results in synthesis of addition polyimide adhesives with exceptional high temperature capabilities that show excellent potential for bonding titanium metal, polyimide/graphite composites, and combinations of these materials. Adhesives compatible with materials used in high performance aircraft and spacecraft structures also prove highly desirable in many other applications involving similar adherents.

  16. Sticky fingers: Adhesive properties of human fingertips.

    PubMed

    Spinner, Marlene; Wiechert, Anke B; Gorb, Stanislav N

    2016-02-29

    Fingertip friction is a rather well studied subject. Although the phenomenon of finger stickiness is known as well, the pull-off force and the adhesive strength of human finger tips have never been previously quantified. For the first time, we provided here characterization of adhesive properties of human fingers under natural conditions. Human fingers can generate a maximum adhesive force of 15mN on a smooth surface of epoxy resin. A weak correlation of the adhesive force and the normal force was found on all test surfaces. Up to 300mN load, an increase of the normal force leads to an increase of the adhesive force. On rough surfaces, the adhesive strength is significantly reduced. Our data collected from untreated hands give also an impression of an enormous scattering of digital adhesion depending on a large set of inter-subject variability and time-dependent individual factors (skin texture, moisture level, perspiration). The wide inter- and intra-individual range of digital adhesion should be considered in developing of technical and medical products.

  17. Recurrent spinal adhesive arachnoiditis. A case report.

    PubMed

    de Mattos, J P; André, C; Couto, B A

    1988-03-01

    Spinal adhesive arachnoiditis is not an uncommon disease, usually having a monophasic course. We studied an atypical patient with recurrent spinal adhesive arachnoiditis nine years after intrathecal anesthesia and the first attack of the disease. Also noteworthy was the favorable evolution after surgery.

  18. Polyurethane adhesive with improved high temperature properties

    NASA Technical Reports Server (NTRS)

    Stuckey, J. M.

    1977-01-01

    A polyurethane resin with paste activator, capable of providing useful bond strengths over the temperature range of -184 C to 149 C, is described. The adhesive system has a pot life of over one hour. Tensile shear strength ratings are given for various adhesive formulations.

  19. Predicting Failure Initiation in Structural Adhesive Joints

    DTIC Science & Technology

    2012-08-15

    Elastoplástico de Adhesivos – Modeling, characterization and simulation of the elastoplastic behavior of adhesives. Maestría en Ciencia de Materiales...adhesive and a 1018 steel”. Maestría en Ciencia de Materiales. Centro de Investigación en Materiales Avanzados S.C. May 2012.  Abstract: In the

  20. Cell-Cell Adhesion and Breast Cancer.

    DTIC Science & Technology

    1998-01-01

    Staging of breast cancer. In: K.I. Bland and E.M. Copeland (eds.), The breast: Comprehensive management of benign and malignant diseases , pp. 313-330... desmosomes . The physical strength of adhesion between two cells is likely to be dependent upon a number of factors, including the number of adhesion

  1. 21 CFR 878.4380 - Drape adhesive.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Drape adhesive. 878.4380 Section 878.4380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4380 Drape adhesive. (a) Identification....

  2. 21 CFR 878.4380 - Drape adhesive.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Drape adhesive. 878.4380 Section 878.4380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4380 Drape adhesive. (a) Identification....

  3. 21 CFR 878.4380 - Drape adhesive.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Drape adhesive. 878.4380 Section 878.4380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4380 Drape adhesive. (a) Identification....

  4. 21 CFR 878.4380 - Drape adhesive.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Drape adhesive. 878.4380 Section 878.4380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4380 Drape adhesive. (a) Identification....

  5. 21 CFR 878.4380 - Drape adhesive.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Drape adhesive. 878.4380 Section 878.4380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4380 Drape adhesive. (a) Identification....

  6. Adhesion mechanism of a gecko-inspired oblique structure with an adhesive tip for asymmetric detachment

    NASA Astrophysics Data System (ADS)

    Sekiguchi, Yu; Takahashi, Kunio; Sato, Chiaki

    2015-12-01

    An adhesion model of an oblique structure with an adhesive tip is proposed by considering a limiting stress for adhesion to describe the detachment mechanism of gecko foot hairs. When a force is applied to the root of the oblique structure, normal and shear stresses are generated at contact and the adhesive tip is detached from the surface when reaching the limiting stress. An adhesion criterion that considers both the normal and shear stresses is introduced, and the asymmetric detachment of the oblique structure is theoretically investigated. In addition, oblique beam array structures are manufactured, and an inclination effect of the structure on the asymmetric detachment is experimentally verified.

  7. Focal Adhesion-Independent Cell Migration.

    PubMed

    Paluch, Ewa K; Aspalter, Irene M; Sixt, Michael

    2016-10-06

    Cell migration is central to a multitude of physiological processes, including embryonic development, immune surveillance, and wound healing, and deregulated migration is key to cancer dissemination. Decades of investigations have uncovered many of the molecular and physical mechanisms underlying cell migration. Together with protrusion extension and cell body retraction, adhesion to the substrate via specific focal adhesion points has long been considered an essential step in cell migration. Although this is true for cells moving on two-dimensional substrates, recent studies have demonstrated that focal adhesions are not required for cells moving in three dimensions, in which confinement is sufficient to maintain a cell in contact with its substrate. Here, we review the investigations that have led to challenging the requirement of specific adhesions for migration, discuss the physical mechanisms proposed for cell body translocation during focal adhesion-independent migration, and highlight the remaining open questions for the future.

  8. Coating to enhance metal-polymer adhesion

    SciTech Connect

    Parthasarathi, A.; Mahulikar, D.

    1996-12-31

    An ultra-thin electroplated coating has been developed to enhance adhesion of metals to polymers. The coating was developed for microelectronic packaging applications where it greatly improves adhesion of metal leadframes to plastic molding compounds. Recent tests show that the coating enhances adhesion of different metals to other types of adhesives as well and may thus have wider applicability. Results of adhesion tests with this coating, as well as its other characteristics such as corrosion resistance, are discussed. The coating is a very thin transparent electroplated coating containing zinc and chromium. It has been found to be effective on a variety of metal surfaces including copper alloys, Fe-Ni alloys, Al alloys, stainless steel, silver, nickel, Pd/Ni and Ni-Sn. Contact resistance measurements show that the coating has little or no effect on electrical resistivity.

  9. Synthetic Polypeptide Mimics of Marine Adhesives.

    PubMed

    Yu; Deming

    1998-07-28

    Water soluble copolypeptides containing l-dihydroxyphenylalanine (DOPA) and l-lysine were prepared by ring-opening polymerization of alpha-amino acid N-carboxyanhydride (NCA) monomers. We have prepared a range of different copolymers to probe the effects of functional group composition on adhesive and cross-linking behavior. Aqueous solutions of these copolymers, when mixed with a suitable oxidizing agent (e.g., O2, mushroom tyrosinase, Fe3+, H2O2, or IO4-), formed cross-linked networks that were found to form moisture-resistant adhesive bonds to a variety of substrates (e.g., aluminum, steel, glass, and plastics). It was found that successful adhesive formation was dependent on oxidation conditions, with chemical oxidants giving the best results. Optimized systems were found to form adhesive bonds that rival in strength those formed by natural marine adhesive proteins. Our synthetic systems are readily prepared in large quantities and require no enzymes or other biological components.

  10. Critical length scale controls adhesive wear mechanisms

    PubMed Central

    Aghababaei, Ramin; Warner, Derek H.; Molinari, Jean-Francois

    2016-01-01

    The adhesive wear process remains one of the least understood areas of mechanics. While it has long been established that adhesive wear is a direct result of contacting surface asperities, an agreed upon understanding of how contacting asperities lead to wear debris particle has remained elusive. This has restricted adhesive wear prediction to empirical models with limited transferability. Here we show that discrepant observations and predictions of two distinct adhesive wear mechanisms can be reconciled into a unified framework. Using atomistic simulations with model interatomic potentials, we reveal a transition in the asperity wear mechanism when contact junctions fall below a critical length scale. A simple analytic model is formulated to predict the transition in both the simulation results and experiments. This new understanding may help expand use of computer modelling to explore adhesive wear processes and to advance physics-based wear laws without empirical coefficients. PMID:27264270

  11. Two distinct mechanisms of fibroblast adhesion

    NASA Astrophysics Data System (ADS)

    Harper, P. A.; Juliano, R. L.

    1981-03-01

    The adhesion of cells to the connective tissue matrix is commonly thought to be governed by fibronectin, a pericellular glycoprotein with binding sites for cell surfaces, collagen and glycosaminoglycans. Here we report evidence that Chinese hamster ovary (CHO) cells possess an alternative mechanism for adhesion which is independent of fibronectin. Cells of a variant CHO clone called ADVF11 are defective in their ability to adhere to fibronectin-coated substrata, but can adhere to a substratum coated with SAM (substrate-attached material), a pericellular material produced by fibroblasts. The adhesion of wild-type CHO cells to fibronectin-coated substrata and adhesion of ADVF11 cells to SAM-coated substrata are differentially sensitive to proteolytic treatment. This suggests that there are two distinct adhesion mechanisms for CHO cells, only one of which is dependent on fibronectin.

  12. Adhesion of microchannel-based complementary surfaces.

    PubMed

    Singh, Arun K; Bai, Ying; Nadermann, Nichole; Jagota, Anand; Hui, Chung-Yuen

    2012-03-06

    We show that highly enhanced and selective adhesion can be achieved between surfaces patterned with complementary microchannel structures. An elastic material, poly(dimethylsiloxane) (PDMS), was used to fabricate such surfaces by molding into a silicon master with microchannel profiles patterned by photolithography. We carried out adhesion tests on both complementary and mismatched microchannel/micropillar surfaces. Adhesion, as measured by the energy release rate required to propagate an interfacial crack, can be enhanced by up to 40 times by complementary interfaces, compared to a flat control, and slightly enhanced for some special noncomplementary samples, despite the nearly negligible adhesion for other mismatched surfaces. For each complementary surface, we observe defects in the form of visible striations, where pillars fail to insert fully into the channels. The adhesion between complementary microchannel surfaces is enhanced by a combination of a crack-trapping mechanism and friction between a pillar and channel and is attenuated by the presence of defects.

  13. Adhesive arachnoiditis after lumbar myelography.

    PubMed

    Suolanen, J

    1977-08-01

    Of 1500 myelographies, 99 patients had subsequent myelographies from which the prevalence of adhesive arachnoiditis caused by the initial investigation could be calculated. Three different water-soluble contrast agents had been used in the initial study: Kontrast U (800 patients), Dimer-X (400 patients), and Conray (300 patients) and the subsets of patients restudied represented 6%, 8% and 8% respectively of the whole series. After the first myelography 68 patients had no operation, 31 patients had hemilaminectomy. Conray produced arachnoid changes in 71% of the nonoperated patients. This differed significantly from the 43% caused by Kontrast U, and the 27% evoked by Dimer-X. The same trend was evident in the operated subset. The severity of the arachnoid changes was greater after Conray. Analysis of the iodine content of the different contrast media and comparison with similar series suggested that hyperosmolarity of the agent was responsible for the changes.

  14. Carbon nanotube dry adhesives with temperature-enhanced adhesion over a large temperature range

    NASA Astrophysics Data System (ADS)

    Xu, Ming; Du, Feng; Ganguli, Sabyasachi; Roy, Ajit; Dai, Liming

    2016-11-01

    Conventional adhesives show a decrease in the adhesion force with increasing temperature due to thermally induced viscoelastic thinning and/or structural decomposition. Here, we report the counter-intuitive behaviour of carbon nanotube (CNT) dry adhesives that show a temperature-enhanced adhesion strength by over six-fold up to 143 N cm-2 (4 mm × 4 mm), among the strongest pure CNT dry adhesives, over a temperature range from -196 to 1,000 °C. This unusual adhesion behaviour leads to temperature-enhanced electrical and thermal transports, enabling the CNT dry adhesive for efficient electrical and thermal management when being used as a conductive double-sided sticky tape. With its intrinsic thermal stability, our CNT adhesive sustains many temperature transition cycles over a wide operation temperature range. We discover that a `nano-interlock' adhesion mechanism is responsible for the adhesion behaviour, which could be applied to the development of various dry CNT adhesives with novel features.

  15. Carbon nanotube dry adhesives with temperature-enhanced adhesion over a large temperature range

    PubMed Central

    Xu, Ming; Du, Feng; Ganguli, Sabyasachi; Roy, Ajit; Dai, Liming

    2016-01-01

    Conventional adhesives show a decrease in the adhesion force with increasing temperature due to thermally induced viscoelastic thinning and/or structural decomposition. Here, we report the counter-intuitive behaviour of carbon nanotube (CNT) dry adhesives that show a temperature-enhanced adhesion strength by over six-fold up to 143 N cm−2 (4 mm × 4 mm), among the strongest pure CNT dry adhesives, over a temperature range from −196 to 1,000 °C. This unusual adhesion behaviour leads to temperature-enhanced electrical and thermal transports, enabling the CNT dry adhesive for efficient electrical and thermal management when being used as a conductive double-sided sticky tape. With its intrinsic thermal stability, our CNT adhesive sustains many temperature transition cycles over a wide operation temperature range. We discover that a ‘nano-interlock' adhesion mechanism is responsible for the adhesion behaviour, which could be applied to the development of various dry CNT adhesives with novel features. PMID:27849052

  16. Adhesion Control between Resist and Photomask Blank

    NASA Astrophysics Data System (ADS)

    Kurihara, Masaaki; Hatakeyama, Sho; Yoshida, Kouji; Abe, Makoto; Totsukawa, Daisuke; Morikawa, Yasutaka; Mohri, Hiroshi; Hoga, Morihisa; Hayashi, Naoya; Ohtani, Hiroyuki; Fujihira, Masamichi

    2009-06-01

    Most problems in photomask fabrication such as pattern collapse, haze, and cleaning damage are related to the behavior of surfaces and interfaces of resists, opaque layers, and quartz substrates. Therefore, it is important to control the corresponding surface and interface energies in photomask fabrication processes. In particular, adhesion analysis in microscopic regions is strongly desirable to optimize material and process designs in photomask fabrication. We applied the direct peeling (DP) method with a scanning probe microscope (SPM) tip and measured the adhesion of resist patterns on Cr and quartz surfaces for photomask process optimization. We also studied the effect of tip shape on the reproducibility of adhesion measurements and the dependence of collapse behavior on the resist profile. We measured lateral forces between the resulting collapsed resist pillar and the Cr or the quartz surface before and after the sliding and related these observed lateral forces to the static and kinetic frictional forces, respectively. We also studied the effect of surface modification of the Cr and quartz surfaces with silanization reagents on adhesion measured with the DP method. Resist adhesion could be controlled by surface modification using silanes. We also discuss the relationship between the adhesion observed with the DP method and the properties of the modified surfaces including water contact angles and local adhesive forces measured from force-distance curves with an SPM.

  17. Strategies to Minimize Adhesion Formation After Surgery

    PubMed Central

    Lazarou, George; Mondesir, Carlene; Wei, Kai; Khullar, Poonan; Ogden, Lorna

    2011-01-01

    Objectives: To compare the potential for postoperative laparoscopic adhesion formation utilizing either monopolar cautery or ultrasonic energy and to determine whether there is added benefit with the addition of a suspension of hyaluronate/carboxymethylcellulose in saline versus saline alone. Methods: Injuries were induced in rabbits by using monopolar cautery on 1 uterine horn and adjacent sidewall and ultrasonic energy on the opposite. Hyaluronate/ carboxymethylcellulose or saline was added to every other animal. Autopsies were performed after 3 weeks. Clinical and pathologic scoring of adhesions was performed by blinded investigators. Results: A very significant difference occurred in pathologic adhesion scores favoring the ultrasonic scalpel when the animals were treated with saline. However, a borderline significant difference was found in pathologic scores favoring the ultrasonic scalpel compared to the monopolar cautery. There was no significant difference in clinical adhesion scores between the 2 modalities. No significant difference in either score was found with the addition of hyaluronate/carboxymethylcellulose or saline with either instrument. Conclusion: No benefit was found for adhesion prevention with hyaluronate/carboxymethylcellulose. Although no reduction was achieved in clinical adhesions, the ultrasonic scalpel resulted in fewer histologic signs of tissue inflammation in the early postoperative period, suggesting that further clinical adhesions might develop over time with cautery. PMID:21985723

  18. Adhesion in ceramics and magnetic media

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1989-01-01

    When a ceramic is brought into contact with a metal or a polymeric material such as a magnetic medium, strong bonds form between the materials. For ceramic-to-metal contacts, adhesion and friction are strongly dependent on the ductility of the metals. Hardness of metals plays a much more important role in adhesion and friction than does the surface energy of metals. Adhesion, friction, surface energy, and hardness of a metal are all related to its Young's modulus and shear modulus, which have a marked dependence on the electron configuration of the metal. An increase in shear modulus results in a decrease in area of contact that is greater than the corresponding increase in surface energy (the fond energy) with shear modulus. Consequently, the adhesion and friction decrease with increasing shear modulus. For ceramics in contact with polymeric magnetic tapes, environment is extremely important. For example, a nitrogen environment reduces adhesion and friction when ferrite contacts polymeric tape, whereas a vacuum environment strengthens the ferrite-to-tape adhesion and increases friction. Adhesion and friction are strongly dependent on the particle loading of the tape. An increase in magnetic particle concentration increases the complex modulus of the tape, and a lower real area of contact and lower friction result.

  19. Capillary adhesion forces between flexible fibers

    NASA Astrophysics Data System (ADS)

    Duprat, Camille; Protière, Suzie

    2016-11-01

    We consider the capillary adhesion produced by a drop placed between two elastic fibers. We measure the force exerted by the drop as we vary the inter-fiber distance, and report two types of wet adhesion: a weak capillary adhesion, where a liquid drop bridges the fibers, and a strong elastocapillary adhesion where the liquid is spread between two collapsed fibers. The weak adhesion is characterized by a force that increases linearly with the liquid length. With flexible fibers, the force exerted by the drop can induce deformation and rapid collapse, or zipping, of the fibers. This zipping results in a sudden increase of the wetted length and a force that departs from the linear evolution. As the inter-fiber distance is subsequently increased, the liquid length decreases while the fibers deformation increases, and the force actually reaches a plateau, i.e. remains constant until unzipping, or detachment of the fibers occurs. We measure the value of this plateau, i.e. the maximal adhesion force, as we vary the drop volume and the fibers elasticity. We also show that flexibility extends capillary adhesion to inter-fiber distances impossible to reach with rigid fibers, while keeping a constant pull-out force characteristic of the elastocapillary coupling.

  20. Thrombospondin-induced adhesion of human platelets.

    PubMed Central

    Tuszynski, G P; Kowalska, M A

    1991-01-01

    Washed human unactivated platelets attached and spread on thrombospondin (TSP)-coated microtiter plates. Platelet adhesion was promoted by divalent cations Mn2+, Mg2+, and Ca2+ as compared to buffer having all divalent cations complexed with EDTA. TSP-dependent adhesion was inhibited by anti-TSP fab fragments, an anti-TSP monoclonal antibody, an RGD-containing peptide, complex-specific anti-glycoprotein (GP)IIb-IIIa monoclonal antibodies (A2A9 or AP-2) and anti-VLA-2 monoclonal antibodies (6F1 and Gi9), but not by rabbit preimmune fab fragments, mouse IgG, an anti-GPIIIa monoclonal antibody, or monoclonal antibodies against either the human vitronectin receptor, glycocalicin, or GPIV. At saturating concentrations, anti-GPIIb-IIIa inhibited adhesion by 40-60%. Glanzman's thrombasthenic platelets, which lack GPIIb-IIIa, adhered to TSP to the same extent as anti-GPIIb-IIIa-treated normal platelets or 40-60% as well as untreated normal platelets. Antibody 6F1 (5-10 micrograms/ml) inhibited platelet adhesion of both normal and thrombasthenic platelets by 84-100%. Both VLA-2 antibodies also inhibited collagen-induced platelet adhesion, but had no effect on fibronectin-induced adhesion of normal platelets. These data indicate that platelets specifically adhere to TSP and that this adhesion is mediated through GPIIb-IIIa and/or VLA-2. Images PMID:2010551

  1. Morphology and genesis of asymmetric adhesion warts—a new adhesion surface structure

    NASA Astrophysics Data System (ADS)

    Olsen, Henrik; Due, Poul H.; Clemmensen, Lars B.

    1989-02-01

    Adhesion surface structures have been studied during their formation on a fluvial bar in East Greenland. Two main types occurred: adhesion ripples and asymmetric adhesion warts. Adhesion ripples formed on moist surfaces; their crests lay transverse to the wind direction and they migrated by trapping dry wind-blown sand on their steep fronts. Asymmetric adhesion warts (new structure) formed because of falling moisture content by preferred upwind migration of small protuberances on the adhesion ripples. The protuberances were apparently inherited from an initial rain sculpturing of the bar surface. The asymmetric adhesion warts, here described for the first time, were elongate parallel to the wind, associated with steep upwind-facing fronts and commonly displayed sand-shadow tails tapering in a downwind direction. A study of Devonian flood-basin deposits (Hornelen Basin, Norway) revealed the existence of adhesion surface structures very similar to their modern analogues. The Devonian examples were associated with rain-sculptured surfaces which are believed to have controlled the morphology of the adhesion surface structures as in the modern example. The orientation of the ancient adhesion surface structures is here used for determination of the palaeowind, which blew from the ENE.

  2. Adhesion of Dental Materials to Tooth Structure

    NASA Astrophysics Data System (ADS)

    Mitra, Sumita B.

    2000-03-01

    The understanding and proper application of the principles of adhesion has brought forth a new paradigm in the realm of esthetic dentistry. Modern restorative tooth procedures can now conserve the remaining tooth-structure and also provide for the strengthening of the tooth. Adhesive restorative techniques call for the application and curing of the dental adhesive at the interface between the tooth tissue and the filling material. Hence the success of the restoration depends largely on the integrity of this interface. The mechanism of adhesion of the bonding materials to the dental hard tissue will be discussed in this paper. There are four main steps that occur during the application of the dental adhesive to the oral hard tissues: 1) The first step is the creation of a microstructure in the tooth enamel or dentin by means of an acidic material. This can be through the application of a separate etchant or can be accomplished in situ by the adhesive/primer. This agent has to be effective in removing or modifying the proteinaceous “smear” layer, which would otherwise act as a weak boundary layer on the surface to be bonded. 2) The primer/adhesive must then be able to wet and penetrate the microstructure created in the tooth. Since the surface energies of etched enamel and that of etched dentin are different finding one material to prime both types of dental tissues can be quite challenging. 3) The ionomer types of materials, particularly those that are carboxylate ion-containing, can chemically bond with the calcium ions of the hydroxyapatite mineral. 4) Polymerization in situ allows for micromechanical interlocking of the adhesive. The importance of having the right mechanical properties of the cured adhesive layer and its role in absorbing and dissipating stresses encountered by a restored tooth will also be discussed.

  3. Improving controllable adhesion on both rough and smooth surfaces with a hybrid electrostatic/gecko-like adhesive

    PubMed Central

    Ruffatto, Donald; Parness, Aaron; Spenko, Matthew

    2014-01-01

    This paper describes a novel, controllable adhesive that combines the benefits of electrostatic adhesives with gecko-like directional dry adhesives. When working in combination, the two technologies create a positive feedback cycle whose adhesion, depending on the surface type, is often greater than the sum of its parts. The directional dry adhesive brings the electrostatic adhesive closer to the surface, increasing its effect. Similarly, the electrostatic adhesion helps engage more of the directional dry adhesive fibrillar structures, particularly on rough surfaces. This paper presents the new hybrid adhesive's manufacturing process and compares its performance to three other adhesive technologies manufactured using a similar process: reinforced PDMS, electrostatic and directional dry adhesion. Tests were performed on a set of ceramic tiles with varying roughness to quantify its effect on shear adhesive force. The relative effectiveness of the hybrid adhesive increases as the surface roughness is increased. Experimental data are also presented for different substrate materials to demonstrate the enhanced performance achieved with the hybrid adhesive. Results show that the hybrid adhesive provides up to 5.1× greater adhesion than the electrostatic adhesive or directional dry adhesive technologies alone. PMID:24451392

  4. The development of low temperature curing adhesives

    NASA Technical Reports Server (NTRS)

    Green, H. E.; Sutherland, J. D.; Hom, J. M.; Sheppard, C. H.

    1975-01-01

    An approach for the development of a practical low temperature (293 K-311 K/68 F-100 F) curing adhesive system based on a family of amide/ester resins was studied and demonstrated. The work was conducted on resin optimization and adhesive compounding studies. An improved preparative method was demonstrated which involved the reaction of an amine-alcohol precursor, in a DMF solution with acid chloride. Experimental studies indicated that an adhesive formulation containing aluminum powder provided the best performance when used in conjunction with a commercial primer.

  5. Adhesive bonding using variable frequency microwave energy

    DOEpatents

    Lauf, Robert J.; McMillan, April D.; Paulauskas, Felix L.; Fathi, Zakaryae; Wei, Jianghua

    1998-01-01

    Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy.

  6. Method of making thermally removable adhesives

    DOEpatents

    Aubert, James H.

    2004-11-30

    A method of making a thermally-removable adhesive is provided where a bismaleimide compound, a monomeric furan compound, containing an oxirane group an amine curative are mixed together at an elevated temperature of greater than approximately 90.degree. C. to form a homogeneous solution, which, when cooled to less than approximately 70.degree. C., simultaneously initiates a Diels-Alder reaction between the furan and the bismaleimide and a epoxy curing reaction between the amine curative and the oxirane group to form a thermally-removable adhesive. Subsequent heating to a temperature greater than approximately 100.degree. C. causes the adhesive to melt and allows separation of adhered pieces.

  7. Ice adhesion on super-hydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Kulinich, S. A.; Farzaneh, M.

    2009-06-01

    In this study, ice adhesion strength on flat hydrophobic and rough super-hydrophobic coatings with similar surface chemistry (based on same fluoropolymer) is compared. Glaze ice, similar to naturally accreted, was prepared on the surfaces by spraying super-cooled water microdroplets at subzero temperature. Ice adhesion was evaluated by spinning the samples at constantly increasing speed until ice delamination occurred. Super-hydrophobic surfaces with different contact angle hysteresis were tested, clearly showing that the latter, along with the contact angle, also influences the ice-solid adhesion strength.

  8. Weld bonding of titanium with polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Sheppard, C. H.; Orell, M. K.

    1975-01-01

    A conductive adhesive primer and a capillary flow adhesive were developed for weld bonding titanium alloy joints. Both formulations contained ingredients considered to be non-carcinogenic. Lap-shear joint test specimens and stringer-stiffened panels were weld bonded using a capillary flow process to apply the adhesive. Static property information was generated for weld bonded joints over the temperature range of 219K (-65 F) to 561K (550 F). The capillary flow process was demonstrated to produce weld bonded joints of equal strength to the weld through weld bonding process developed previously.

  9. Adhesive bonding using variable frequency microwave energy

    DOEpatents

    Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L.; Fathi, Z.; Wei, J.

    1998-08-25

    Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy. 26 figs.

  10. Adhesive bonding using variable frequency microwave energy

    DOEpatents

    Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L.; Fathi, Z.; Wei, J.

    1998-09-08

    Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy. 26 figs.

  11. Echinoderm adhesive secretions: from experimental characterization to biotechnological applications.

    PubMed

    Flammang, P; Santos, R; Haesaerts, D

    2005-01-01

    Adhesion is a way of life in echinoderms. Indeed, all the species belonging to this phylum use adhesive secretions extensively for various vital functions. According to the species or to the developmental stage considered, different adhesive systems may be recognized. (1) The tube feet or podia are organs involved in attachment to the substratum, locomotion, feeding or burrowing. Their temporary adhesion relies on a duo-gland adhesive system resorting to both adhesive and de-adhesive secretions. (2) The larval adhesive organs allow temporary attachment of larvae during settlement and strong fixation during metamorphosis. (3) The Cuvierian tubules are sticky defence organs occurring in some holothuroid species. Their efficacy is based on the instantaneous release of a quick-setting adhesive. All these systems rely on different types of adhesion and therefore differ in the way they operate, in their structure and in the composition of their adhesive. In addition to fundamental interests in echinoderm bioadhesives, a substantial impetus behind understanding these adhesives are the potential technological applications that can be derived from their knowledge. These applications cover two broad fields of applied research: design of water-resistant adhesives and development of new antifouling strategies. In this context, echinoderm adhesives could offer novel features or performance characteristics for biotechnological applications. For example, the rapidly attaching adhesive of Cuvierian tubules, the releasable adhesive of tube feet or the powerful adhesive of asteroid larvae could each be useful to address particular bioadhesion problems.

  12. Adhesion-induced receptor segregation and adhesion plaque formation: A model membrane study.

    PubMed Central

    Kloboucek, A; Behrisch, A; Faix, J; Sackmann, E

    1999-01-01

    A model system to study the control of cell adhesion by receptor-mediated specific forces, universal interactions, and membrane elasticity is established. The plasma membrane is mimicked by reconstitution of homophilic receptor proteins into solid supported membranes and, together with lipopolymers, into giant vesicles with the polymers forming an artificial glycocalix. The homophilic cell adhesion molecule contact site A, a lipid-anchored glycoprotein from cells of the slime mold Dictyostelium discoideum, is used as receptor. The success of the reconstitution, the structure and the dynamics of the model membranes are studied by various techniques including film balance techniques, micro fluorescence, fluorescence recovery after photobleaching, electron microscopy, and phase contrast microscopy. The interaction of the functionalized giant vesicles with the supported bilayer is studied by reflection interference contrast microscopy, and the adhesion strength is evaluated quantitatively by a recently developed technique. At low receptor concentrations adhesion-induced receptor segregation in the membranes leads to decomposition of the contact zone between membranes into domains of strong (receptor-mediated) adhesion and regions of weak adhesion while continuous zones of strong adhesion form at high receptor densities. The adhesion strengths (measured in terms of the spreading pressure S) of the various states of adhesion are obtained locally by analysis of the vesicle contour near the contact line in terms of elastic boundary conditions of adhesion: the balance of tensions and moments. The spreading pressure of the weak adhesion zones is S approximately 10(-9) J/m(2) and is determined by the interplay of gravitation and undulation forces whereas the spreading pressure of the tight adhesion domains is of the order S approximately 10(-6) J/m(2). PMID:10512849

  13. Heat-shrinkable film improves adhesive bonds

    NASA Technical Reports Server (NTRS)

    Johns, J. M.; Reed, M. W.

    1980-01-01

    Pressure is applied during adhesive bonding by wrapping parts in heat-shrinkable plastic film. Film eliminates need to vacuum bag or heat parts in expensive autoclave. With procedure, operators are trained quickly, and no special skills are required.

  14. Chemistry technology: Adhesives and plastics: A compilation

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Technical information on chemical formulations for improving and/or producing adhesives is presented. Data are also reported on polymeric plastics with special characteristics or those plastics that were produced by innovative means.

  15. Adhesion of gels by silica particle.

    PubMed

    Abe, Hidekazu; Hara, Yusuke; Maeda, Shingo; Hashimoto, Shuji

    2014-03-06

    In this study, a method for achieving adhesion between two positively charged gels with high mechanical strength was developed. By utilizing a silica particle dispersion as a binder, the gels easily adhered to each other and remained stable for up to 11 days when immersed in aqueous solution. The adhesion force between the two positively charged semi-interpenetrating network gels with the silica particle was measured to be up to approximately 20 kPa, which is around 10 times larger than that with a charged polymer-rich liquid as a cross-linker (approximately 1.5 kPa). It was demonstrated that the adhesion force was a result of two types of interactions: an electrostatic attractive force between the cationic gel surface and hydrogen bonding among the silica particles. In addition, it was shown that the adhesion force was dependent on solution pH, which was attributed to changes in the charge of the silica particles.

  16. Adhesion properties of chain-forming ferrofluids.

    PubMed

    Lira, Sérgio A; Miranda, José A

    2009-04-01

    Denser and highly magnetized ferrofluids exhibit several non-Newtonian behaviors attributed to the formation of magnetic particle chains. We investigate the rheological and adhesive properties during tensile deformation of a confined chain-forming ferrofluid subjected to a radial magnetic field. Both the magnetoviscous contribution to the viscosity and the adhesive force are derived analytically. The response of the system to changes in the length of the chains is examined under zero and nonzero shear circumstances. Our results indicate that the existence of chains has a significant impact on the adhesive strength as well as on the viscosity of the ferrofluid, allowing it to display both shear-thinning and shear-thickening regimes. These findings open up the possibility of monitoring complex rheological responses of such fluids with the assistance of applied magnetic fields, allowing a more accurate assessment of their adhesive properties.

  17. Regulation of integrin-mediated adhesions

    PubMed Central

    Iwamoto, Daniel V.; Calderwood, David A.

    2015-01-01

    Integrins are heterodimeric transmembrane adhesion receptors that couple the actin cytoskeleton to the extracellular environment and bidirectionally relay signals across the cell membrane. These processes are critical for cell attachment, migration, differentiation, and survival, and therefore play essential roles in metazoan development, physiology, and pathology. Integrin-mediated adhesions are regulated by diverse factors, including the conformation-specific affinities of integrin receptors for their extracellular ligands, the clustering of integrins and their intracellular binding partners into discrete adhesive structures, mechanical forces exerted on the adhesion, and the intracellular trafficking of integrins themselves. Recent advances shed light onto how the interaction of specific intracellular proteins with the short cytoplasmic tails of integrins controls each of these activities. PMID:26189062

  18. Biomimetic mushroom-shaped fibrillar adhesive microstructure.

    PubMed

    Gorb, S; Varenberg, M; Peressadko, A; Tuma, J

    2007-04-22

    To improve the adhesive properties of artificial fibrillar contact structures, the attachment systems of beetles from the family Chrysomelidae were chosen to serve as a model. Biomimetic mushroom-shaped fibrillar adhesive microstructure inspired by these systems was characterized using a variety of measurement techniques and compared with a control flat surface made of the same material. Results revealed that pull-off force and peel strength of the structured specimens are more than twice those of the flat specimens. In contrast to the control system, the structured one is found to be very tolerant to contamination and able to recover its adhesive properties after being washed in a soap solution. Based on the combination of several geometrical principles found in biological attachment devices, the presented microstructure exhibits a considerable step towards the development of an industrial dry adhesive.

  19. Advances in the Pathogenesis of Adhesion Development

    PubMed Central

    Awonuga, Awoniyi O.; Belotte, Jimmy; Abuanzeh, Suleiman; Fletcher, Nicole M.; Diamond, Michael P.

    2014-01-01

    Over the past several years, there has been increasing recognition that pathogenesis of adhesion development includes significant contributions of hypoxia induced at the site of surgery, the resulting oxidative stress, and the subsequent free radical production. Mitochondrial dysfunction generated by surgically induced tissue hypoxia and inflammation can lead to the production of reactive oxygen and nitrogen species as well as antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase which when optimal have the potential to abrogate mitochondrial dysfunction and oxidative stress, preventing the cascade of events leading to the development of adhesions in injured peritoneum. There is a significant cross talk between the several processes leading to whether or not adhesions would eventually develop. Several of these processes present avenues for the development of measures that can help in abrogating adhesion formation or reformation after intraabdominal surgery. PMID:24520085

  20. Viscoelastic study of an adhesively bonded joint

    NASA Technical Reports Server (NTRS)

    Joseph, P. F.

    1983-01-01

    The plane strain problem of two dissimilar orthotropic plates bonded with an isotropic, linearly viscoelastic adhesive is considered. Both the shear and the normal stresses in the adhesive are calculated for various geometries and loading conditions. Transverse shear deformations of the adherends are taken into account, and their effect on the solution is shown in the results. All three inplane strains of the adhesive are included. Attention is given to the effect of temperature, both in the adhesive joint problem and to the heat generation in a viscoelastic material under cyclic loading. This separate study is included because heat generation and or spatially varying temperature are at present too difficult to account for in the analytical solution of the bonded joint, but whose effect can not be ignored in design.

  1. Molecular dynamics simulation of interfacial adhesion

    SciTech Connect

    Yarovsky, I.; Chaffee, A.L.

    1996-12-31

    Chromium salts are often used in the pretreatment stages of steel painting processes in order to improve adhesion at the metal oxide/primer interface. Although well established empirically, the chemical basis for the improved adhesion conferred by chromia is not well understood. A molecular level understanding of this behaviour should provide a foundation for the design of materials offering improved adhesion control. Molecular modelling of adhesion involves simulation and analysis of molecular behaviour at the interface between two interacting phases. The present study concerns behaviour at the boundary between the metal coated steel surface (with or without chromium pretreatment) and an organic primer based on a solid epoxide resin produced from bisphenol A and epichlorohydrin. An epoxy resin oligomer of molecular weight 3750 was used as the model for the primer.

  2. Bacterial contamination of cucumber fruit through adhesion.

    PubMed

    Reina, Laura D; Fleming, Henry P; Breidt, Frederick

    2002-12-01

    In this study, the adhesion of bacteria to fresh cucumber surfaces in aqueous suspension was shown to be dependent on time of incubation, inoculum species and concentration, and temperature. The adhesion of bacteria to the fruit in wash water was less extensive at lower temperatures and shorter exposure times. Various species of bacteria were adsorbed to cucumber surfaces in the following relative order: Salmonella Typhimurium > Staphylococcus aureus > Lactobacillus plantarum > Listeria monocytogenes. Cells were adsorbed at all temperatures tested (5, 15, 25, and 35 degrees C) at levels that depended on incubation time, but the numbers of cells adsorbed were larger at higher incubation temperatures. Levels of adhesion of bacteria to dewaxed fruit were higher for L. monocytogenes and lower for Salmonella Typhimurium, L. plantarum, and S. aureus than were levels of adhesion to waxed fruit.

  3. Ice adhesions in relation to freeze stress.

    PubMed

    Olien, C R; Smith, M N

    1977-10-01

    In freezing, competitive interaction between ice and hydrophilic plant substances causes an energy of adhesion to develop through the interstitial liquid. The thermodynamic basis for the adhesion energy is discussed, with estimates of the energies involved. In this research, effects of adhesion energy were observed microscopically in conjunction with energies of crystallization and frost desiccation. The complex character of ice in intact crown tissue of winter barley (Hordeum vulgare L.) and the problems of sectioning frozen tissue without producing artifacts led to an alternative study of single barley cells in a mesh of ice and cell wall polymers. Adhesions between ice, cell wall polymers, and the plasmalemma form a complexly interacting system in which the pattern of crystallization is a major factor in determination of stress and injury.

  4. Adhesion in hydrogels and model glassy polymers

    NASA Astrophysics Data System (ADS)

    Guvendiren, Murat

    Two main topics are addressed in this dissertation: (1) adhesion in hydrogels; (2) interfacial interactions between model glassy polymers. A self-assembly technique for the formation of hydrogels from acrylic triblock copolymer solutions was developed, based on vapor phase solvent exchange. Structure formation in the gels was characterized by small angle X-ray scattering, and swelling was measured in controlled pH buffer solutions. Strong gels are formed with polymer weight fractions between 0.01 and 0.15, and with shear moduli between 0.6 kPa and 3.5 kPa. Adhesive functionality, based on 3,4-dihydroxy-L-phenylalanine (DOPA) was also incorporated into the triblock copolymers. The effect of DOPA concentration on gel formation and swelling was investigated in detail. The adhesive properties of DOPA-functionalized hydrogels on TiO2 were investigated with an axisymmetric adhesion method. It was shown that the presence of DOPA enhances the adhesive properties of the hydrogels, but that the effect is minimized at pH values below 10, where the DOPA groups are hydrophobic. Thin film membranes were produced in order to study the specific interactions between DOPA and TiO2 and DOPA and tissue, using a membrane inflation method. The presence of DOPA in the membranes enhances the adhesion on TiO 2 and tissue, although adhesion to tissue requires that the DOPA groups be oxidized while in contact with the tissue of interest. Porous hydrogel scaffolds for tissue engineering applications were formed by adding salt crystals to the triblock copolymer solution prior to solvent exchange. Salt was then leached out by immersing the gel into water. Structures of the porous hydrogels were characterized by confocal laser scanning microscopy. These hydrogels were shown to be suitable for tissue regeneration and drug delivery applications. Diffusion-mediated adhesion between two component miscible polymer systems having very different glassy temperatures was also investigated. Axisymmetric

  5. Strengthening of dental adhesives via particle reinforcement.

    PubMed

    Belli, Renan; Kreppel, Stefan; Petschelt, Anselm; Hornberger, Helga; Boccaccini, Aldo R; Lohbauer, Ulrich

    2014-09-01

    The bond between methacrylic polymer adhesives and dental restoratives is not perfect and may fail either in the short or in the long term. This study aims to evaluate the effects of particle incorporation in a self-etch model adhesive on mechanical and physical properties that are relevant during application and service. Filled adhesives containing 5, 10, 15 or 25wt% glass fillers were compared to their unfilled counterpart in terms of water sorption and solubility; viscosity and dynamic viscosity during polymerization were recorded using rheological measurements and compared to FTIR analysis of the real-time degree of cure. Elastic modulus and ultimate tensile strength measurements were performed in uniaxial tension; the energy to fracture was used to calculate the fracture toughness of the adhesives. Finally, the experimental adhesives were applied on dentin substrate to test the bond strength using the microtensile test. Results showed that the incorporation of 5-10wt% nanofiller to self-etching dental adhesives is efficient in accelerating the polymerization reaction and increasing the degree of cure without compromising the film viscosity for good wettability or water sorption and solubility. Fillers increased the elastic modulus, tensile strength and fracture toughness to a plateau between 5 and 15wt% filler concentration, and despite the tendency to form agglomerations, active crack pinning/deflection toughening mechanisms have been observed. The bond strength between resin composite and dentin was also improved when adhesives with up to 10wt% fillers were used, with no additional improvements with further packing. The use of fillers to reinforce dental adhesives may therefore be of great practical benefit by improving curing and mechanical properties.

  6. New pressure-sensitive silicone adhesive

    NASA Technical Reports Server (NTRS)

    Leiffer, J. L.; Stoops, W. E., Jr.; St. Clair, T. L.; Watkins, V. E., Jr.; Kelly, T. P.

    1981-01-01

    Adhesive for high or low temperatures does not stretch severely under load. It is produced by combining intermediate-molecular-weight pressure sensitive adhesive which does not cure with silicone resin that cures with catalyst to rubbery tack-free state. Blend of silicone tackifier and cured rubbery silicone requires no solvents in either atmospheric or vacuum environments. Ratio of ingredients varies for different degrees of tack, creep resistance, and tensile strength.

  7. Surface Contamination of Adhesive Bonding Materials.

    DTIC Science & Technology

    1979-12-01

    test is illustrated in Figure 19. The specimen is then exposed to some environment such as high temperature and humidity and monitored for crack growth...bonded and subsequently failed at high humidity and elevated temperatures indicate early crack propagation at the adhesive-oxide interface. Large...Adhesive Tape (A) and a Point Not Exposed to the Tape (B) 21 Positive Secondary Ion Mass Spectra from 44 6AI-4V-Ti at Room Temperature (156-1) and after

  8. Cryogenic adhesives and sealants: Abstracted publications

    NASA Technical Reports Server (NTRS)

    Williamson, F. R.; Olien, N. A.

    1977-01-01

    Abstracts of primary documents containing original experimental data on the properties of adhesives and sealants at cryogenic temperatures are presented. The most important references mentioned in each document are cited. In addition, a brief annotation is given for documents considered secondary in nature, such as republications or variations of original reports, progress reports leading to final reports included as primary documents, and experimental data on adhesive properties at temperatures between about 130 K and room temperature.

  9. Tensiometer for Band-Wound Adhesion Studies

    DTIC Science & Technology

    2016-04-08

    Box 12211 Research Triangle Park, NC 27709-2211 hemostasis, hemorrhage, bandage, liver , adhesion REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S...that are of interest to the DoD. 15. SUBJECT TERMS Trauma, hemorrhage, hemostasis, exsanguination, coagulopathy, hemodilution, liver injury...Proposal title: Tensiometer for bandage-wound adhesion studies List of Appendices A. Figure of liver peel test. B. Description of ex vivo

  10. Analytical cell adhesion chromatography reveals impaired persistence of metastatic cell rolling adhesion to P-selectin

    PubMed Central

    Oh, Jaeho; Edwards, Erin E.; McClatchey, P. Mason; Thomas, Susan N.

    2015-01-01

    ABSTRACT Selectins facilitate the recruitment of circulating cells from the bloodstream by mediating rolling adhesion, which initiates the cell–cell signaling that directs extravasation into surrounding tissues. To measure the relative efficiency of cell adhesion in shear flow for in vitro drug screening, we designed and implemented a microfluidic-based analytical cell adhesion chromatography system. The juxtaposition of instantaneous rolling velocities with elution times revealed that human metastatic cancer cells, but not human leukocytes, had a reduced capacity to sustain rolling adhesion with P-selectin. We define a new parameter, termed adhesion persistence, which is conceptually similar to migration persistence in the context of chemotaxis, but instead describes the capacity of cells to resist the influence of shear flow and sustain rolling interactions with an adhesive substrate that might modulate the probability of extravasation. Among cell types assayed, adhesion persistence to P-selectin was specifically reduced in metastatic but not leukocyte-like cells in response to a low dose of heparin. In conclusion, we demonstrate this as an effective methodology to identify selectin adhesion antagonist doses that modulate homing cell adhesion and engraftment in a cell-subtype-selective manner. PMID:26349809

  11. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Pressure-sensitive adhesives. 175.125 Section 175... Substances for Use Only as Components of Adhesives § 175.125 Pressure-sensitive adhesives. Pressure-sensitive... accordance with the following prescribed conditions: (a) Pressure-sensitive adhesives prepared from one or...

  12. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Pressure-sensitive adhesives. 175.125 Section 175... Substances for Use Only as Components of Adhesives § 175.125 Pressure-sensitive adhesives. Pressure-sensitive... accordance with the following prescribed conditions: (a) Pressure-sensitive adhesives prepared from one or...

  13. Hyper-adhesion: a unique property of desmosomes.

    PubMed

    Garrod, David; Tabernero, Lydia

    2014-10-01

    Hyper-adhesion is a unique, strongly adhesive form of desmosomal adhesion that functions to maintain tissue integrity. In this short review, we define hyper-adhesion, summarise the evidence for it in culture and in vivo, discuss its role in development, wound healing, and skin disease, and speculate about its molecular and cellular basis.

  14. Cell-Substrate Adhesion by Amoeboid Cells

    NASA Astrophysics Data System (ADS)

    Flanders, Bret; Panta, Krishna

    Amoeboid migration is a rapid (10 μm min-1) mode of migration that some tumor cells exhibit. To permit such rapid movement, the adhesive contacts between the cell and the substrate must be relatively short-lived and weak. In this study, we investigate the basic adhesive character of amoeboid cells (D. discoideum) in contact with silanized glass substrates. We observe the initiation and spreading of the adhesive contacts that these cells establish as they settle under gravity onto the substrate and relax towards mechanical equilibrium. The use of interference reflection microscopy and cellular tethering measurements have allowed us to determine the basic adhesive properties of the cell: the membrane-medium interfacial energy; the bending modulus; the equilibrium contact angle; and the work of adhesion. We find the time scale on which settling occurs to be longer than expected. Implications of these results on adhesion and migration will be discussed. The authors are grateful for support from NSF (CBET-1451903) and NIH (1R21EY026392).

  15. Contact angle hysteresis, adhesion, and marine biofouling.

    PubMed

    Schmidt, Donald L; Brady, Robert F; Lam, Karen; Schmidt, Dale C; Chaudhury, Manoj K

    2004-03-30

    Adhesive and marine biofouling release properties of coatings containing surface-oriented perfluoroalkyl groups were investigated. These coatings were prepared by cross-linking a copolymer of 1H,1H,2H,2H-heptadecafluorodecyl acrylate and acrylic acid with a copolymer of poly(2-isopropenyl-2-oxazoline) and methyl methacrylate at different molar ratios. The relationships between contact angle, contact angle hysteresis, adhesion, and marine biofouling were studied. Adhesion was determined by peel tests using pressure-sensitive adhesives. The chemical nature of the surfaces was studied by using X-ray photoelectron spectroscopy. Resistance to marine biofouling of an optimized coating was studied by immersion in seawater and compared to previous, less optimized coatings. The adhesive release properties of the coatings did not correlate well with the surface energies of the coatings estimated from the static and advancing contact angles nor with the amount of fluorine present on the surface. The adhesive properties of the surfaces, however, show a correlation with water receding contact angles and contact angle hysteresis (or wetting hysteresis) resulting from surface penetration and surface reconstruction. Coatings having the best release properties had both the highest cross-link density and the lowest contact angle hysteresis. An optimized coating exhibited unprecedented resistance to marine biofouling. Water contact angle hysteresis appears to correlate with marine biofouling resistance.

  16. Yielding Elastic Tethers Stabilize Robust Cell Adhesion

    PubMed Central

    Whitfield, Matt J.; Luo, Jonathon P.; Thomas, Wendy E.

    2014-01-01

    Many bacteria and eukaryotic cells express adhesive proteins at the end of tethers that elongate reversibly at constant or near constant force, which we refer to as yielding elasticity. Here we address the function of yielding elastic adhesive tethers with Escherichia coli bacteria as a model for cell adhesion, using a combination of experiments and simulations. The adhesive bond kinetics and tether elasticity was modeled in the simulations with realistic biophysical models that were fit to new and previously published single molecule force spectroscopy data. The simulations were validated by comparison to experiments measuring the adhesive behavior of E. coli in flowing fluid. Analysis of the simulations demonstrated that yielding elasticity is required for the bacteria to remain bound in high and variable flow conditions, because it allows the force to be distributed evenly between multiple bonds. In contrast, strain-hardening and linear elastic tethers concentrate force on the most vulnerable bonds, which leads to failure of the entire adhesive contact. Load distribution is especially important to noncovalent receptor-ligand bonds, because they become exponentially shorter lived at higher force above a critical force, even if they form catch bonds. The advantage of yielding is likely to extend to any blood cells or pathogens adhering in flow, or to any situation where bonds are stretched unequally due to surface roughness, unequal native bond lengths, or conditions that act to unzip the bonds. PMID:25473833

  17. Adhesion of oil to kaolinite in water.

    PubMed

    Lebedeva, Evgenia V; Fogden, Andrew

    2010-12-15

    Uniform coats of kaolinite particles on a flat glass substrate were prepared to be sufficiently smooth and thin to allow reliable measurement of contact angles of captive crude oil drops in a range of salt solutions, without any particle removal. The contact angle hysteresis was used to infer the extent of oil adhesion via rupture of the intervening water film and anchoring of charged groups to kaolinite. For sodium chloride solutions, adhesion decreases monotonically with pH and/or salinity, with strong adhesion only manifested under acidic conditions with salinity at most 0.1 M. Calcium chloride solutions at pH around 6 switch from strong adhesion in the range 0.001-0.01 M to weak adhesion at higher concentrations. For all mixtures of sodium and calcium chlorides investigated, a total ionic strength above 0.1 M guarantees a weak adhesion of oil to kaolinite. Results are qualitatively consistent with theoretical expectations of electrostatic interactions, with H(+) and Ca(2+) being potential-determining ions for both interfaces.

  18. Controlled Adhesion of Silicone Elastomer Surfaces

    NASA Astrophysics Data System (ADS)

    Owen, Michael

    2000-03-01

    Opportunities exist for controllably enhancing the adhesion of silicone surfaces, ranging from modest enhancement of release force levels of pressure-sensitive adhesive (PSA) release liners by incorporation of adhesion promoters known as high release additives (HRA), to permanent bonding of silicone elastomers using surface modification techniques such as plasma or corona treatment. Although only a part of the complex interaction of factors contributing to adhesion, surface properties such as wettability are a critical component in the understanding and control of release and adhesion phenomena. Surface characterization studies of low-surface-energy silicones before and after various adhesion modification strategies are reviewed. The silicones include polydimethylsiloxane (PDMS) and fluorosiloxane elastomers and coatings. Techniques used include contact angle, the Johnson, Kendall and Roberts (JKR) contact mechanics approach, scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS). Topics addressed are: use of HRA in PDMS release liners, the interaction of PDMS PSAs with polytetrafluoroethylene (PTFE), and the effect of plasma treatment on PDMS and fluorosiloxane surfaces.

  19. Cytotoxicity of Dental Adhesives In Vitro

    PubMed Central

    Koulaouzidou, Elisabeth A.; Helvatjoglu-Antoniades, Maria; Palaghias, George; Karanika-Kouma, Artemis; Antoniades, Dimitrios

    2009-01-01

    Objectives The purpose of this study was to evaluate the cytotoxic effect of six dental adhesives (Admira Bond, Clearfil Liner Bond 2V, ED Primer II, Fuji Bond LC, Gluma Comfort Bond, and NanoBond) applied to cell cultures. Methods The experiments were performed on two cell lines, rat pulp cells (RPC-C2A) and human lung fibroblasts (MRC5). Samples of the adhesives were light-cured and placed in culture medium for 24 hours. The extraction media was applied on the RPC-C2A and the MRC5 cells. Complete medium was used as a control. Cytotoxicity was evaluated with a modified sulforhodamine B (SRB) assay after 24 hours of exposure. Results The cell survival of RPC-C2A cells exposed to Fuji Bond LC, NanoBond, Clearfil Liner Bond 2V, ED Primer II, Admira Bond and Gluma Comfort Bond was 73%, 67%, 50%, 20%, 18% and 5% respectively, relative to the cell survival with the control medium. In the MRC5 cell line, the relative survival was 98%, 80%, 72%, 41%, 19% and 7% after exposure to NanoBond, Fuji Bond LC, Clearfil Liner Bond 2V, ED Primer II, Admira Bond and Gluma Comfort Bond, respectively. Conclusions Different types of dental adhesives showed different cytotoxic effects on cells in vitro. The self-etch adhesives were superior in terms of cytotoxicity. The different cytotoxic effects of dental adhesives should be considered when selecting an appropriate adhesive for operative restorations. PMID:19262725

  20. Single-molecule mechanics of mussel adhesion

    NASA Astrophysics Data System (ADS)

    Lee, Haeshin; Scherer, Norbert F.; Messersmith, Phillip B.

    2006-08-01

    The glue proteins secreted by marine mussels bind strongly to virtually all inorganic and organic surfaces in aqueous environments in which most adhesives function poorly. Studies of these functionally unique proteins have revealed the presence of the unusual amino acid 3,4-dihydroxy-L-phenylalanine (dopa), which is formed by posttranslational modification of tyrosine. However, the detailed binding mechanisms of dopa remain unknown, and the chemical basis for mussels' ability to adhere to both inorganic and organic surfaces has never been fully explained. Herein, we report a single-molecule study of the substrate and oxidation-dependent adhesive properties of dopa. Atomic force microscopy (AFM) measurements of a single dopa residue contacting a wet metal oxide surface reveal a surprisingly high strength yet fully reversible, noncovalent interaction. The magnitude of the bond dissociation energy as well as the inability to observe this interaction with tyrosine suggests that dopa is critical to adhesion and that the binding mechanism is not hydrogen bond formation. Oxidation of dopa, as occurs during curing of the secreted mussel glue, dramatically reduces the strength of the interaction to metal oxide but results in high strength irreversible covalent bond formation to an organic surface. A new picture of the interfacial adhesive role of dopa emerges from these studies, in which dopa exploits a remarkable combination of high strength and chemical multifunctionality to accomplish adhesion to substrates of widely varying composition from organic to metallic. 3,4-dihydroxylphenylalanine | atomic force microscopy | mussel adhesive protein

  1. Creation of Abdominal Adhesions in Mice.

    PubMed

    Marshall, Clement D; Hu, Michael S; Leavitt, Tripp; Barnes, Leandra A; Cheung, Alexander T M; Malhotra, Samir; Lorenz, H Peter; Longaker, Michael T

    2016-08-27

    Abdominal adhesions consist of fibrotic tissue that forms in the peritoneal space in response to an inflammatory insult, typically surgery or intraabdominal infection. The precise mechanisms underlying adhesion formation are poorly understood. Many compounds and physical barriers have been tested for their ability to prevent adhesions after surgery with varying levels of success. The mouse and rat are important models for the study of abdominal adhesions. Several different techniques for the creation of adhesions in the mouse and rat exist in the literature. Here we describe a protocol utilizing abrasion of the cecum with sandpaper and sutures placed in the right abdominal sidewall. The mouse is anesthetized and the abdomen is prepped. A midline laparotomy is created and the cecum is identified. Sandpaper is used to gently abrade the surface of the cecum. Next, several figure-of-eight sutures are placed into the peritoneum of the right abdominal sidewall. The abdominal cavity is irrigated, a small amount of starch is applied, and the incision is closed. We have found that this technique produces the most consistent adhesions with the lowest mortality rate.

  2. Bistability of cell adhesion in shear flow.

    PubMed

    Efremov, Artem; Cao, Jianshu

    2011-09-07

    Cell adhesion plays a central role in multicellular organisms helping to maintain their integrity and homeostasis. This complex process involves many different types of adhesion proteins, and synergetic behavior of these proteins during cell adhesion is frequently observed in experiments. A well-known example is the cooperation of rolling and stationary adhesion proteins during the leukocytes extravasation. Despite the fact that such cooperation is vital for proper functioning of the immune system, its origin is not fully understood. In this study we constructed a simple analytic model of the interaction between a leukocyte and the blood vessel wall in shear flow. The model predicts existence of cell adhesion bistability, which results from a tug-of-war between two kinetic processes taking place in the cell-wall contact area-bond formation and rupture. Based on the model results, we suggest an interpretation of several cytoadhesion experiments and propose a simple explanation of the existing synergy between rolling and stationary adhesion proteins, which is vital for effective cell adherence to the blood vessel walls in living organisms.

  3. Design guidelines for hybrid microcircuits; organic adhesives for hybrid microcircuits

    NASA Technical Reports Server (NTRS)

    Perkins, K. L.; Licari, J. J.

    1975-01-01

    The properties of organic adhesives were studied to acquire an adequate information base to generate a guideline document for the selection of adhesives for use in high reliability hybrid microcircuits. Specific areas covered include: (1) alternate methods for determining the outgassing of cured adhesives; (2) effects of long term aging at 150C on the electrical properties of conductive adhesives; (3) effects of shelf life age on adhesive characteristics; (4) bond strengths of electrically conductive adhesives on thick film gold metallization, (5) a copper filled adhesive; (6) effects of products outgassed from cured adhesives on device electrical parameters; (7) metal migration from electrically conductive adhesives; and (8) ionic content of electrically insulative adhesives. The tests performed during these investigations are described, and the results obtained are discussed in detail.

  4. Single-Phase Photo-Cross-Linkable Bioinspired Adhesive for Precise Control of Adhesion Strength.

    PubMed

    Harper, Tristan; Slegeris, Rimantas; Pramudya, Irawan; Chung, Hoyong

    2017-01-18

    A bioinspired, modular terpolymer adhesive, poly(N-methacryloyl-3,4-dihydroxyl-l-phenylalanine-co-9-(acryloyloxy)butyl anthracene-9-carboxylate-co-acrylic acid), has been synthesized containing three different functionalities: a photo-cross-linking segment, a wet interfacial adhesion segment, and a water-soluble segment. The synthesized adhesive polymer is the first example of a single-phase, photo-cross-linkable adhesive which does not require additional photoinitiator or other cross-linking agents. The terpolymer demonstrates strong adhesion when it swells in water and/or ethanol. The terpolymer is composed of three repeating units: N-methacryloyl-3,4-dihydroxyl-l-phenylalanine (MDOPA), which has been known to generate strong adhesion under wet conditions, poly(acrylic acid), which has been known to increase water solubility of polymers, and a photo-cross-linking segment consisting of an anthracene-based monomer used for enhancement of cohesion properties via UV irradiation (352 nm). A photomediated [4 + 4] cycloaddition reaction of anthracene results in the cross-linking of individual polymer chains after interfacial adhesion between substrates and adhesive polymers. Chemically, the covalent photo-cross-linking was confirmed by UV-vis, (1)H NMR, and gel permeation chromatography (GPC). The cross-linking-fortified cohesion of the adhesive polymer network yields strengthened cohesion properties of the bulk material. The photoreaction was conveniently controlled via the duration of UV-irradiation. The adhesion properties of new adhesives were characterized by lap shear strength on transparent Mylar film and glasses after the adhesive was swollen in biologically friendly solvents including water and ethanol. The adhesion strength (J/m(2)) was enhanced by 850% under 352 nm UV-irradiation. Multiple application variables were tested to determine the optimal conditions, such as solvent, concentration, polymer composition, and substrate. The best adhesion properties were

  5. Adhesive characterization in prestressed piezoelectric laminates

    NASA Astrophysics Data System (ADS)

    Hodges, Charles A.; Mossi, Karla M.; Scott, Lisa A.

    2003-08-01

    Pre-stressed piezoelectric laminates, consisting of one or more metal layers and a piezoelectric material bonded together with an adhesive, have been widely studied over the past few years, both numerically and experimentally. Most of the current research has concentrated on the effect of the metal layers, types and geometry, along with variations in the active layer of the laminate. Historically, the adhesive layer has been neglected as a contributing factor in the overall performance of the final device. This paper attempts to address the effect of the adhesive line thickness and its influence on the performance of pre-stressed piezoelectric laminates under specific boundary conditions. All laminates tested were constructed with the following lay-up: 0.354 mm thick stainless steel, adhesive, 0.381 mm PZT ceramic, adhesive, and a 0.0254 mm aluminum layer. The devices having an adhesive line thickness of 0.169 mm were classified as group A, and group B were the devices with an adhesive line thickness of 0.036 mm. The adhesive line thickness for group A was approximately 21% more than the line thickness of group B. The devices were tested in a simply supported, free-free condition under a series of loads at a constant frequency of 5 Hz over a voltage range from 400 to 800 Volts peak-to-peak. Displacement was measured using loads of 25, 50, 75, 100, and 200 grams for each actuator. The data from each group was averaged and compared. The results showed group B generated more displacement at the same "arm weight" applied as compared to group A. However, only three samples for group B were measured since the rest of the samples failed during testing. Failure of the devices of group B may be due to the ultimate stress of the devices and their ability to lift a load under those conditions. The study demonstrated that adhesive layer thickness, along with the manufacturing process, has to be taken into account when developing an application that requires load

  6. Contribution from pressure-sensitive adhesives

    NASA Astrophysics Data System (ADS)

    Cunningham, Gilbert

    1996-03-01

    The successful use of many security papers, foils and films depends on the technology of chemical fastening systems -- especially pressure sensitive adhesives. These are adhesives activated not by heat or by the evaporation of water or some other solvent, but simply by the act of application -- by pressure. These adhesives provide the means whereby laminations, substrates and seals are made effective. In addition to their physical properties these adhesives are often required to possess optical properties to allow the security materials to be visibly active and indeed the adhesive system may itself contribute as a carrier for a variety of security materials. Recent advances in adhesives chemistry have made it possible to achieve virtually all the required physical performance characteristics combined with a choice of optical properties ranging from total opacity to invisibility and including controlled translucency and tinting. The implications for security printing and packaging are important. Opacity is easy to achieve, for example by loading the adhesive with aluminum powder, by the selection of totally opaque materials like metallized film or by various printing processes. But achieving transparency is a different matter, and transparency is mandatory for applications involving the protection of documents, photographs, etc. with a clear film over-laminate. Obvious examples would be for passports, visas and other personal identification. But some security devices may themselves require protection; for example holograms or embossings. And transparency in the test laboratory is not enough. The Australian driving licence is stuck to the windshield, so the transparency of the adhesive must be sustained over long periods without deterioration due to prolonged u/v exposure, climatic conditions or aging. The commercial label market has helped to push the technology forward. There is a strong demand for the 'no-label look' for packaging of clear plastic and glass

  7. Adhesion of latex films. Influence of surfactants

    SciTech Connect

    Charmeau, J.Y.; Kientz, E.; Holl, Y.

    1996-12-31

    In the applications of film forming latexes in paint, paper, coating, adhesive, textile industries, one of the most important property of latex films is adhesion onto a support. From the point of view of adhesion, latex films have two specificities. The first one arises from the particular structure of the film which is usually not homogeneous but retains to a certain extent the memory of the particles it was made from. These structure effects are clearly apparent when one compares mechanical or adhesion properties of pure latex films and of films of the same polymers but prepared from a solution. Latex films show higher Young`s moduli and lower adhesion properties than solution films. The second specificity of latex films comes from the presence of the surfactant which was used in the synthesis and as stabilizer for the latex. Most industrial latexes contain low amounts of surfactant, typically in the range 0.1 to 2-3 wt%. However, being usually incompatible with the polymer, the surfactant is not homogeneously distributed in the film. It tends to segregate towards the film-air or film-support interfaces or to form domains in the bulk of the film. Distribution of surfactants in latex films has been studied by several authors. The influence of the surfactant on adhesion, as well as on other properties, is thus potentially very important. This article presents the results of the authors investigation of surfactant effects on adhesion properties of latex films. To the authors knowledge, there is no other example, in the open literature, of this kind of study.

  8. Mussel adhesion is dictated by time-regulated secretion and molecular conformation of mussel adhesive proteins.

    PubMed

    Petrone, Luigi; Kumar, Akshita; Sutanto, Clarinda N; Patil, Navinkumar J; Kannan, Srinivasaraghavan; Palaniappan, Alagappan; Amini, Shahrouz; Zappone, Bruno; Verma, Chandra; Miserez, Ali

    2015-10-28

    Interfacial water constitutes a formidable barrier to strong surface bonding, hampering the development of water-resistant synthetic adhesives. Notwithstanding this obstacle, the Asian green mussel Perna viridis attaches firmly to underwater surfaces via a proteinaceous secretion (byssus). Extending beyond the currently known design principles of mussel adhesion, here we elucidate the precise time-regulated secretion of P. viridis mussel adhesive proteins. The vanguard 3,4-dihydroxy-L-phenylalanine (Dopa)-rich protein Pvfp-5 acts as an adhesive primer, overcoming repulsive hydration forces by displacing surface-bound water and generating strong surface adhesion. Using homology modelling and molecular dynamics simulations, we find that all mussel adhesive proteins are largely unordered, with Pvfp-5 adopting a disordered structure and elongated conformation whereby all Dopa residues reside on the protein surface. Time-regulated secretion and structural disorder of mussel adhesive proteins appear essential for optimizing extended nonspecific surface interactions and byssus' assembly. Our findings reveal molecular-scale principles to help the development of wet-resistant adhesives.

  9. Inhibition of Adhesion Molecule Gene Expression and Cell Adhesion by the Metabolic Regulator PGC-1α.

    PubMed

    Minsky, Neri; Roeder, Robert G

    2016-01-01

    Cell adhesion plays an important role in determining cell shape and function in a variety of physiological and pathophysiological conditions. While links between metabolism and cell adhesion were previously suggested, the exact context and molecular details of such a cross-talk remain incompletely understood. Here we show that PGC-1α, a pivotal transcriptional co-activator of metabolic gene expression, acts to inhibit expression of cell adhesion genes. Using cell lines, primary cells and mice, we show that both endogenous and exogenous PGC-1α down-regulate expression of a variety of cell adhesion molecules. Furthermore, results obtained using mRNA stability measurements as well as intronic RNA expression are consistent with a transcriptional effect of PGC-1α on cell adhesion gene expression. Interestingly, the L2/L3 motifs of PGC-1α, necessary for nuclear hormone receptor activation, are only partly required for inhibition of several cell adhesion genes by PGC-1α. Finally, PGC-1α is able to modulate adhesion of primary fibroblasts and hepatic stellate cells to extracellular matrix proteins. Our results delineate a cross talk between a central pathway controlling metabolic regulation and cell adhesion, and identify PGC-1α as a molecular link between these two major cellular networks.

  10. Mussel adhesion is dictated by time-regulated secretion and molecular conformation of mussel adhesive proteins

    NASA Astrophysics Data System (ADS)

    Petrone, Luigi; Kumar, Akshita; Sutanto, Clarinda N.; Patil, Navinkumar J.; Kannan, Srinivasaraghavan; Palaniappan, Alagappan; Amini, Shahrouz; Zappone, Bruno; Verma, Chandra; Miserez, Ali

    2015-10-01

    Interfacial water constitutes a formidable barrier to strong surface bonding, hampering the development of water-resistant synthetic adhesives. Notwithstanding this obstacle, the Asian green mussel Perna viridis attaches firmly to underwater surfaces via a proteinaceous secretion (byssus). Extending beyond the currently known design principles of mussel adhesion, here we elucidate the precise time-regulated secretion of P. viridis mussel adhesive proteins. The vanguard 3,4-dihydroxy-L-phenylalanine (Dopa)-rich protein Pvfp-5 acts as an adhesive primer, overcoming repulsive hydration forces by displacing surface-bound water and generating strong surface adhesion. Using homology modelling and molecular dynamics simulations, we find that all mussel adhesive proteins are largely unordered, with Pvfp-5 adopting a disordered structure and elongated conformation whereby all Dopa residues reside on the protein surface. Time-regulated secretion and structural disorder of mussel adhesive proteins appear essential for optimizing extended nonspecific surface interactions and byssus' assembly. Our findings reveal molecular-scale principles to help the development of wet-resistant adhesives.

  11. Focal adhesion kinase maintains, but not increases the adhesion of dental pulp cells.

    PubMed

    Qian, Yuyan; Shao, Meiying; Zou, Wenlin; Wang, Linyan; Cheng, Ran; Hu, Tao

    2017-02-25

    Focal adhesion kinase (FAK) functions as a key enzyme in the integrin-mediated adhesion-signalling pathway. Here, we aimed to investigate the effects of FAK on adhesion of human dental pulp (HDP) cells. We transfected lentiviral vectors to silence or overexpress FAK in HDP cells ex vivo. Early cell adhesion, cell survival and focal contacts (FCs)-related proteins (FAK and paxillin) were examined. By using immunofluorescence, the formation of FCs and cytoskeleton was detected, respectively. We found that both adhesion and survival of HDP cells were suppressed by FAK inhibition. However, FAK overexpression slightly inhibited cell adhesion and exhibited no change in cell survival compared with the control. A thick rim of cytoskeleton accumulated and smaller dot-shaped FCs appeared in FAK knockdown cells. Phosphorylation of paxillin (p-paxillin) was inhibited in FAK knockdown cells, verifying that the adhesion was inhibited. Less cytoskeleton and elongated FCs were observed in FAK-overexpressed cells. However, p-paxillin had no significant difference compared with the control. In conclusion, the data suggest that FAK maintains cell adhesion, survival and cytoskeleton formation, but excessive FAK has no positive effects on these aspects.

  12. Enzymatic degradation of adhesive-dentin interfaces produced by mild self-etch adhesives.

    PubMed

    De Munck, Jan; Mine, Atsushi; Van den Steen, Philippe E; Van Landuyt, Kirsten L; Poitevin, André; Opdenakker, Ghislain; Van Meerbeek, Bart

    2010-10-01

    Endogenous matrix metalloproteinases (MMPs) released by adhesive procedures may degrade collagen in the hybrid layer and so compromise the bonding effectiveness of etch-and-rinse adhesives. In this study, endogenous enzymatic degradation was evaluated for several simplified self-etch adhesives. In addition, primers were modified by adding two MMP inhibitors: chlorhexidine, a commonly used disinfectant, but also a non-specific MMP inhibitor; and SB-3CT, a specific inhibitor of MMP-2 and MMP-9. Gelatin zymography of fresh human dentin powder was used to identify the enzymes released by the adhesives. Micro-tensile bond strength (μTBS) testing was used to assess the mechanical properties of resin-dentin interfaces over time. In none of the experimental groups treated with the mild self-etch adhesives was MMP-2 and/or MMP-9 identified. Also, no difference in the μTBS was measured for the inhibitor-modified and the control inhibitor-free adhesives after 6 months of water storage. It is concluded that in contrast to etch-and-rinse adhesives, the involvement of endogenous MMP-2 and MMP-9 in the bond-degradation process is minimal for mild self-etch adhesives.

  13. Mussel adhesion is dictated by time-regulated secretion and molecular conformation of mussel adhesive proteins

    PubMed Central

    Petrone, Luigi; Kumar, Akshita; Sutanto, Clarinda N.; Patil, Navinkumar J.; Kannan, Srinivasaraghavan; Palaniappan, Alagappan; Amini, Shahrouz; Zappone, Bruno; Verma, Chandra; Miserez, Ali

    2015-01-01

    Interfacial water constitutes a formidable barrier to strong surface bonding, hampering the development of water-resistant synthetic adhesives. Notwithstanding this obstacle, the Asian green mussel Perna viridis attaches firmly to underwater surfaces via a proteinaceous secretion (byssus). Extending beyond the currently known design principles of mussel adhesion, here we elucidate the precise time-regulated secretion of P. viridis mussel adhesive proteins. The vanguard 3,4-dihydroxy-L-phenylalanine (Dopa)-rich protein Pvfp-5 acts as an adhesive primer, overcoming repulsive hydration forces by displacing surface-bound water and generating strong surface adhesion. Using homology modelling and molecular dynamics simulations, we find that all mussel adhesive proteins are largely unordered, with Pvfp-5 adopting a disordered structure and elongated conformation whereby all Dopa residues reside on the protein surface. Time-regulated secretion and structural disorder of mussel adhesive proteins appear essential for optimizing extended nonspecific surface interactions and byssus' assembly. Our findings reveal molecular-scale principles to help the development of wet-resistant adhesives. PMID:26508080

  14. Nanorough titanium surfaces reduce adhesion of Escherichia coli and Staphylococcus aureus via nano adhesion points.

    PubMed

    Lüdecke, Claudia; Roth, Martin; Yu, Wenqi; Horn, Uwe; Bossert, Jörg; Jandt, Klaus D

    2016-09-01

    Microbial adhesion to natural and synthetic materials surfaces is a key issue e.g. in food industry, sewage treatment and most importantly in the biomedical field. The current development and progress in nanoscale structuring of materials surfaces to control microbial adhesion requires an advanced understanding of the microbe-material-interaction. This study aimed to investigate the nanostructure of the microbe-material-interface and link it to microbial adhesion kinetics as function of titanium surface nanoroughness to gain new insight into controlling microbial adhesion via materials' surface nanoroughness. Adhesion of Escherichia coli and Staphylococcus aureus was statistically significantly reduced (p≤0.05) by 55.6 % and 40.5 %, respectively, on physical vapor deposited titanium thin films with a nanoroughness of 6nm and the lowest surface peak density compared to 2nm with the highest surface peak density. Cross-sectioning of the microbial cells with a focused ion beam (FIB) and SEM imaging provided for the first time direct insight into the titanium-microbe-interface. High resolution SEM micrographs gave evidence that the surface peaks are the loci of initial contact between the microbial cells and the material's surface. In a qualitative model we propose that the initial microbial adhesion on nanorough surfaces is controlled by the titanium surface peak density via nano adhesion points. This new understanding will help towards the design of materials surfaces for controlling microbial adhesion.

  15. Cadherin-11 localizes to focal adhesions and promotes cell–substrate adhesion

    PubMed Central

    Langhe, Rahul P.; Gudzenko, Tetyana; Bachmann, Michael; Becker, Sarah F.; Gonnermann, Carina; Winter, Claudia; Abbruzzese, Genevieve; Alfandari, Dominique; Kratzer, Marie-Claire; Franz, Clemens M.; Kashef, Jubin

    2016-01-01

    Cadherin receptors have a well-established role in cell–cell adhesion, cell polarization and differentiation. However, some cadherins also promote cell and tissue movement during embryonic development and tumour progression. In particular, cadherin-11 is upregulated during tumour and inflammatory cell invasion, but the mechanisms underlying cadherin-11 stimulated cell migration are still incompletely understood. Here, we show that cadherin-11 localizes to focal adhesions and promotes adhesion to fibronectin in Xenopus neural crest, a highly migratory embryonic cell population. Transfected cadherin-11 also localizes to focal adhesions in different mammalian cell lines, while endogenous cadherin-11 shows focal adhesion localization in primary human fibroblasts. In focal adhesions, cadherin-11 co-localizes with β1-integrin and paxillin and physically interacts with the fibronectin-binding proteoglycan syndecan-4. Adhesion to fibronectin mediated by cadherin-11/syndecan-4 complexes requires both the extracellular domain of syndecan-4, and the transmembrane and cytoplasmic domains of cadherin-11. These results reveal an unexpected role of a classical cadherin in cell–matrix adhesion during cell migration. PMID:26952325

  16. 21 CFR 880.5240 - Medical adhesive tape and adhesive bandage.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Personal Use Therapeutic Devices § 880.5240 Medical adhesive tape and adhesive bandage. (a) Identification... together the skin edges of a wound, to support an injured part of the body, or to secure objects to the skin. (b) Classification. Class I (general controls). The device is exempt from the...

  17. 21 CFR 880.5240 - Medical adhesive tape and adhesive bandage.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Personal Use Therapeutic Devices § 880.5240 Medical adhesive tape and adhesive bandage. (a) Identification... together the skin edges of a wound, to support an injured part of the body, or to secure objects to the skin. (b) Classification. Class I (general controls). The device is exempt from the...

  18. Inhibition of Adhesion Molecule Gene Expression and Cell Adhesion by the Metabolic Regulator PGC-1α

    PubMed Central

    Minsky, Neri; Roeder, Robert G.

    2016-01-01

    Cell adhesion plays an important role in determining cell shape and function in a variety of physiological and pathophysiological conditions. While links between metabolism and cell adhesion were previously suggested, the exact context and molecular details of such a cross-talk remain incompletely understood. Here we show that PGC-1α, a pivotal transcriptional co-activator of metabolic gene expression, acts to inhibit expression of cell adhesion genes. Using cell lines, primary cells and mice, we show that both endogenous and exogenous PGC-1α down-regulate expression of a variety of cell adhesion molecules. Furthermore, results obtained using mRNA stability measurements as well as intronic RNA expression are consistent with a transcriptional effect of PGC-1α on cell adhesion gene expression. Interestingly, the L2/L3 motifs of PGC-1α, necessary for nuclear hormone receptor activation, are only partly required for inhibition of several cell adhesion genes by PGC-1α. Finally, PGC-1α is able to modulate adhesion of primary fibroblasts and hepatic stellate cells to extracellular matrix proteins. Our results delineate a cross talk between a central pathway controlling metabolic regulation and cell adhesion, and identify PGC-1α as a molecular link between these two major cellular networks. PMID:27984584

  19. Connexin 43 expressed in endothelial cells modulates monocyte‑endothelial adhesion by regulating cell adhesion proteins.

    PubMed

    Yuan, Dongdong; Sun, Guoliang; Zhang, Rui; Luo, Chenfang; Ge, Mian; Luo, Gangjian; Hei, Ziqing

    2015-11-01

    Adhesion between circulating monocytes and vascular endothelial cells is a key initiator of atherosclerosis. In our previous studies, it was demonstrated that the expression of connexin (Cx)43 in monocytes modulates cell adhesion, however, the effects of the expression of Cx43 in endothelial cells remains to be elucidated. Therefore, the present study investigated the role of the expression of Cx43 in endothelial cells in the process of cell adhesion. A total of four different methods with distinct mechanisms were used to change the function and expression of Cx43 channels in human umbilical vein endothelial cells: Cx43 channel inhibitor (oleamide), enhancer (retinoic acid), overexpression of Cx43 by transfection with pcDNA‑Cx43 and knock‑down of the expression of Cx43 by small interfering RNA against Cx43. The results indicated that the upregulation of the expression of Cx43 enhanced monocyte‑endothelial adhesion and this was markedly decreased by downregulation of Cx43. This mechanism was associated with Cx43‑induced expression of vascular cell adhesion molecule‑1 and intercellular cell adhesion molecule‑1. The effects of Cx43 in endothelial cells was independent of Cx37 or Cx40. These experiments suggested that local regulation of endothelial Cx43 expression within the vasculature regulates monocyte‑endothelial adhesion, a critical event in the development of atherosclerosis and other inflammatory pathologies, with baseline adhesion set by the expression of Cx43. This balance may be crucial in controlling leukocyte involvement in inflammatory cascades.

  20. Supramolecular adhesives to hard surfaces: adhesion between host hydrogels and guest glass substrates through molecular recognition.

    PubMed

    Takashima, Yoshinori; Sahara, Taiga; Sekine, Tomoko; Kakuta, Takahiro; Nakahata, Masaki; Otsubo, Miyuki; Kobayashi, Yuichiro; Harada, Akira

    2014-10-01

    Supramolecular materials based on host-guest interactions should exhibit high selectivity and external stimuli-responsiveness. Among various stimuli, redox and photo stimuli are useful for its wide application. An external stimuli-responsive adhesive system between CD host-gels (CD gels) and guest molecules modified glass substrates (guest Sub) is focused. Here, the selective adhesion between host gels and guest substrates where adhesion depends on molecular complementarity is reported. Initially, it is thought that adhesion of a gel material onto a hard material might be difficult unless many guest molecules modified linear polymers immobilize on the surface of hard materials. However, reversible adhesion of the CD gels is observed by dissociating and re-forming inclusion complex in response to redox and photo stimuli.

  1. The effect of polyethylene glycol adhesion barrier (Spray Gel) on preventing peritoneal adhesions.

    PubMed

    Dasiran, F; Eryilmaz, R; Isik, A; Okan, I; Somay, A; Sahin, M

    2015-01-01

    The prominent cells in the late phase of wound healing during proliferation and matrix deposition are fibroblasts. Foreign materials in the operation site like prosthesis prolong the inflammation and induce fibroblast proliferation (8). 3 different prostheses used in this study induced chronic inflammation and fibrosis and provided an effective repair. Dense and thick adhesions due to fibrosis also induced strong adhesions to omentum and small intestine if only polypropylene mesh used for hernia repair. However, there was no difference between SprayGel treated polypropylene mesh and Sepramesh when compared for fibrosis. It also prevents the intraabdominal adhesion formation. It is nontoxic, sticky adherent, non- immigrant and easy to use both in open and laparoscopic surgeries. This experimental study revealed that polyethyleneglycol applied polypropylene mesh accomplishes hernia repair with significantly less adhesion formation than polypropylene mesh alone while securing a remarkable economy than adhesion barrier coated dual meshes (Tab. 6, Fig. 7, Ref. 23). Text in PDF www.elis.sk.

  2. Shear Strength of Conductive Adhesive Joints on Rigid and Flexible Substrates Depending on Adhesive Quantity

    NASA Astrophysics Data System (ADS)

    Hirman, Martin; Steiner, Frantisek

    2016-05-01

    This article deals with the impact of electrically conductive adhesive quantity on the shear strength of joints glued by adhesives "EPO-TEKⓇ H20S" and "MG8331S" on three types of substrates (FR-4, MELINEXⓇST504, DuPont™ PyraluxⓇAC). These joints were made by gluing chip resistors 1206, 0805 and 0603, with two curing profiles for each adhesive. Different thicknesses of stencil and reductions in the size of the hole in stencils were used for this experiment. These differences have an effect on the quantity of conductive adhesives which must be used on the samples. Samples were measured after the curing process by using a shear strength test applied by the device LabTest 3.030. This article presents the effects of different curing profiles, various types of substrates, and different quantities of adhesives on the mechanical strength of the joint.

  3. BIOLOGICAL ADHESIVES. Adaptive synergy between catechol and lysine promotes wet adhesion by surface salt displacement.

    PubMed

    Maier, Greg P; Rapp, Michael V; Waite, J Herbert; Israelachvili, Jacob N; Butler, Alison

    2015-08-07

    In physiological fluids and seawater, adhesion of synthetic polymers to solid surfaces is severely limited by high salt, pH, and hydration, yet these conditions have not deterred the evolution of effective adhesion by mussels. Mussel foot proteins provide insights about adhesive adaptations: Notably, the abundance and proximity of catecholic Dopa (3,4-dihydroxyphenylalanine) and lysine residues hint at a synergistic interplay in adhesion. Certain siderophores—bacterial iron chelators—consist of paired catechol and lysine functionalities, thereby providing a convenient experimental platform to explore molecular synergies in bioadhesion. These siderophores and synthetic analogs exhibit robust adhesion energies (E(ad) ≥-15 millijoules per square meter) to mica in saline pH 3.5 to 7.5 and resist oxidation. The adjacent catechol-lysine placement provides a "one-two punch," whereby lysine evicts hydrated cations from the mineral surface, allowing catechol binding to underlying oxides.

  4. Ultrasonic Nondestructive Characterization of Adhesive Bonds

    NASA Technical Reports Server (NTRS)

    Qu, Jianmin

    1999-01-01

    Adhesives and adhesive joints are widely used in various industrial applications to reduce weight and costs, and to increase reliability. For example, advances in aerospace technology have been made possible, in part, through the use of lightweight materials and weight-saving structural designs. Joints, in particular, have been and continue to be areas in which weight can be trimmed from an airframe through the use of novel attachment techniques. In order to save weight over traditional riveted designs, to avoid the introduction of stress concentrations associated with rivet holes, and to take full advantage of advanced composite materials, engineers and designers have been specifying an ever-increasing number of adhesively bonded joints for use on airframes. Nondestructive characterization for quality control and remaining life prediction has been a key enabling technology for the effective use of adhesive joints. Conventional linear ultrasonic techniques generally can only detect flaws (delamination, cracks, voids, etc) in the joint assembly. However, more important to structural reliability is the bond strength. Although strength, in principle, cannot be measured nondestructively, a slight change in material nonlinearity may indicate the onset of failure. Furthermore, microstructural variations due to aging or under-curing may also cause changes in the third order elastic constants, which are related to the ultrasonic nonlinear parameter of the polymer adhesive. It is therefore reasonable to anticipate a correlation between changes in the ultrasonic nonlinear acoustic parameter and the remaining bond strength. It has been observed that higher harmonics of the fundamental frequency are generated when an ultrasonic wave passes through a nonlinear material. It seems that such nonlinearity can be effectively used to characterize bond strength. Several theories have been developed to model this nonlinear effect. Based on a microscopic description of the nonlinear

  5. Actin Foci Adhesion of D. discoideum

    NASA Astrophysics Data System (ADS)

    Flanders, Bret; Paneru, Govind

    2014-03-01

    Amoeboid migration is a fast (10 μm min-1) integrin-independent mode of migration that is important with D. discoideum, leukocytes, and breast cancer cells. It is poorly understood, but depends on the establishment of adhesive contacts to the substrate where the cell transmits traction forces. In pre-aggregative D. discoideum, a model system for learning about amoeboid migration, these adhesive contacts are discrete complexes that are known as actin-foci. They have an area of ~ 0.5 μm2 and a lifetime of ~ 20 s. This talk will present measurements of the adhesive character of actin foci that have been obtained using a submicron force transducer that was designed for this purpose. Results on the rupture stresses and lifetimes of individual acting foci under nano-newton level forces will be described in the context of a general theory for cellular adhesion. This theory depends on, essentially, three cellular properties: the membrane-medium surface tension, the number density of adhesion receptors in the membrane, and the receptor-substrate potential energy surface. Therefore, the use of the transducer to determine the surface tension will be presented, as well.

  6. Environmental durability of adhesively bonded joints

    NASA Astrophysics Data System (ADS)

    Butkus, Lawrence Michael

    The goal of this project was to evaluate the environmental durability of adhesively bonded aircraft joints using fracture mechanics. Three aerospace adhesives, two epoxies and one polyimide, were investigated. Adhesive specimens were tested for tensile and toughness behavior. Bonded joint specimens were subject to Mode I, Mode II, and mixed mode fracture and fatigue tests. Prior to testing, selected specimens were exposed for up to 10,000 hours to isothermal and thermally cyclic conditions similar to aircraft service environments. Analysis was accomplished using finite element programs and closed-form solutions. Environmental exposure caused reductions in the failure strain, strength, and toughness, of the adhesive specimens and in the toughness and fatigue threshold of the bonded joint specimens. Specimens exposed to high temperature and humidity prior to testing and those tested at low temperatures indicative of high altitude operations experienced the most significant toughness losses. Results are discussed in terms of their relationship to bonded joint design and should prove valuable to efforts aimed at extending the lives of aging aircraft using bonded repairs as well as to efforts focused on using adhesive bonding for future aerospace structures.

  7. Irrigant divalent cation concentrations influence bacterial adhesion

    PubMed Central

    Dass, Clarissa L.; Walsh, Mary F.; Seo, Sue; Shiratsuchi, Hiroe; Craig, David H.; Basson, Marc D.

    2009-01-01

    Background Surgical wounds are frequently contaminated by microbes, but rarely become infected if the bacterial burden is low, and irrigation is used to reduce contamination. Wound fluids are low in calcium and high in magnesium. We hypothesized that manipulating irrigant divalent cation concentrations might influence bacterial adhesion. Methods Staphylococcus aureus, E. coli, and Pseudomonas aeruginosa were stained with fluorescent Calcein AM before plating onto fibroblast monolayers, collagen I, or uncoated bacteriologic plastic. After one hour, wells were washed with HEPES-buffered pH-balanced sterile water without or with 5mM CaCl2, 5mM MgCl2 or 1mM EDTA+EGTA, and the remaining adherent bacteria were assayed fluorometrically. Results Supplementing the irrigation with magnesium or chelators increased but calcium-supplemented irrigation reduced bacterial adhesion to collagen or fibroblasts. Non-specific electrostatic bacterial adhesion to uncoated plastic was unaffected by calcium. Conclusion Bacterial adhesion to mammalian cells and matrix proteins is influenced by divalent cations, and pathogenic bacteria may be adapted to adhere under the low calcium high magnesium conditions in wounds. Although these results await confirmation for other bacteria, and in vivo validation and safety-testing, they suggest that supplementing wound irrigation with 5mM CaCl2 may reduce bacterial adhesion and subsequent wound infection. PMID:19577252

  8. Probing adhesion forces at the molecular scale

    SciTech Connect

    Thomas, R.C.; Houston, J.E.; Michalske, T.A.

    1996-12-31

    Measurements of adhesion forces at the molecular scale, such as those discussed here, are necessary to understand macroscopic boundary-layer behavior such as adhesion, friction, wear, lubrication, and many other important phenomena. The authors` recent interfacial force microscopy (IFM) studies have provided detailed information about the mechanical response of both self-assembled monolayer (SAM) films and the underlying substrates. In addition, they recently demonstrated that the IFM is useful for studying the chemical nature of such films. In this talk, the authors discuss a new method for studying surface interactions and chemical reactions using the IFM. To quantitatively measure the work of adhesion and bond energies between two organic thin films, they modify both a Au substrate and a Au probe with self-assembling organomercaptan molecules having either the same or different end groups (-CH{sub 3}, -NH{sub 2}, and -COOH), and then analyze the force-versus-displacement curves (force profiles) that result from the approach to contact of the two surfaces. Their results show that the magnitude of the adhesive forces measured between methyl-methyl interactions are in excellent agreement with van der Waals calculations using Lifshitz theory and previous experimentally determined values. Moreover, the measured peak adhesive forces scale as expected for van der Waals, hydrogen-bonding, and acid-base interactions.

  9. Pattern formation in cell membrane adhesion

    NASA Astrophysics Data System (ADS)

    Discher, Dennis; Hategan, A.; Sengupta, K.; Sackmann, E.

    2004-03-01

    Strong adhesion of highly active cells often nucleates focal adhesions or related structures that are, over time, reinforced by cytoskeleton (actin, etc.). Red cells lack such complex adhesion systems, but they are shown here to also exhibit complex spatial patterns within an adhesive contact zone. While strong adhesion and spreading of the red cell to a dense poly-L-lysine surface appears complete in < 1 s by reflective interference microscopy, over longer times of 10-15 min or more distinct patterns in fluorescently labeled membrane components emerge. The fluorescent lipid Fl-PE (fluorescein phosphoethanolamine), in particular, is seen to diffuse and reorganize (eg. worm-like domains of <500 nm) within the contact zone, independent of whether the cell is intact or ruptured. Lipid patterns are accompanied by visible perturbations in band 3 distribution and weaker perturbations in membrane skeleton actin. Although fluorescent poly-L-lysine is shown to be uniform under cells, pressing down on the membrane quenches the lipid patterns and reveals the topographical basis for pattern formation. Regions of strong contact are thus separated by regions where the membrane is more distant from the surface.

  10. Signaling during platelet adhesion and activation

    PubMed Central

    Li, Zhenyu; Delaney, M. Keegan; O’Brien, Kelly A.; Du, Xiaoping

    2011-01-01

    Upon vascular injury, platelets are activated by adhesion to adhesive proteins like von Willebrand factor and collagen, or by soluble platelet agonists like ADP, thrombin, and thromboxane A2. These adhesive proteins and soluble agonists induce signal transduction via their respective receptors. The various receptor-specific platelet activation signaling pathways converge into common signaling events, which stimulate platelet shape change, granule secretion, and ultimately induce the “inside-out” signaling process leading to activation of the ligand binding function of integrin αIIbβ3. Ligand binding to integrin αIIbβ3 mediates platelet adhesion and aggregation and triggers “outside-in” signaling, resulting in platelet spreading, additional granule secretion, stabilization of platelet adhesion and aggregation, and clot retraction. It has become increasingly evident that agonist-induced platelet activation signals also crosstalk with integrin “outside-in” signals to regulate platelet responses. Platelet activation involves a series of rapid positive feedback loops that greatly amplify initial activation signals, and enable robust platelet recruitment and thrombus stabilization. Recent studies have provided novel insight into the molecular mechanisms of these processes. PMID:21071698

  11. Thermodynamics of capillary adhesion between rough surfaces.

    PubMed

    de Boer, M P; de Boer, P C T

    2007-07-01

    According to the Dupré equation, the work of adhesion is equal to the surface energy difference in the separated versus the joined materials minus an interfacial energy term. However, if a liquid is at the interface between two solid materials, evaporation or condensation takes place under equilibrium conditions. The resulting matter exchange is accompanied by heat flow, and can reduce or increase the work of adhesion. Accounting for the energies requires an open-system control volume analysis based on the first law of thermodynamics. Depending on whether evaporation or condensation occurs during separation, a work term that is negative or positive must be added to the surface energy term to calculate the work of adhesion. We develop and apply this energy balance to several different interface geometries and compare the work of adhesion to the surface energy created. The model geometries include a sphere on a flat with limiting approximations and also with an exact solution, a circular disc, and a combination of these representing a rough interface. For the sphere on a flat, the work of adhesion is one half the surface energy created if equilibrium is maintained during the pull-off process.

  12. Raman Imaging of Dental Adhesive Diffusion

    NASA Astrophysics Data System (ADS)

    Wieliczka, D. M.; Kruger, M. B.; Spencer, P.

    1997-03-01

    In this project the dentin/adhesive interface was studied using micro-Raman spectroscopy in conjunction with laser light that is optimized to minimize the sample fluorescence. The commercial dentin adhesives Scotchbond Multi-Purpose Plus(3M) and Superbond (Sun Medical) were placed on coronal dentin substrates that were cut from extracted, unerupted third molars. The Raman spectra were obtained using a Dilor spectrometer with a resolution of 4 cm-1 over the spectral range of 100 to 2000 cm-1. All data were obtained using a Kr+ laser operating at 647 nm, a microscope with a 100x objective and with the sample mounted on a precision linear stage allowing for 0.5 (m positioning. Data were obtained from successive positions on the sample providing a spectral record of the interface from the pure adhesive to the pure dentin. Adhesive penetration into the dentin was determined by comparing the relative intensities of spectral bands attributable to the dentin versus the adhesive.

  13. Elasto-capillarity in insect fibrillar adhesion.

    PubMed

    Gernay, Sophie; Federle, Walter; Lambert, Pierre; Gilet, Tristan

    2016-08-01

    The manipulation of microscopic objects is challenging because of high adhesion forces, which render macroscopic gripping strategies unsuitable. Adhesive footpads of climbing insects could reveal principles relevant for micro-grippers, as they are able to attach and detach rapidly during locomotion. However, the underlying mechanisms are still not fully understood. In this work, we characterize the geometry and contact formation of the adhesive setae of dock beetles (Gastrophysa viridula) by interference reflection microscopy. We compare our experimental results to the model of an elastic beam loaded with capillary forces. Fitting the model to experimental data yielded not only estimates for seta adhesion and compliance in agreement with previous direct measurements, but also previously unknown parameters such as the volume of the fluid meniscus and the bending stiffness of the tip. In addition to confirming the primary role of surface tension for insect adhesion, our investigation reveals marked differences in geometry and compliance between the three main kinds of seta tips in leaf beetles.

  14. Spiders Tune Glue Viscosity to Maximize Adhesion.

    PubMed

    Amarpuri, Gaurav; Zhang, Ci; Diaz, Candido; Opell, Brent D; Blackledge, Todd A; Dhinojwala, Ali

    2015-11-24

    Adhesion in humid conditions is a fundamental challenge to both natural and synthetic adhesives. Yet, glue from most spider species becomes stickier as humidity increases. We find the adhesion of spider glue, from five diverse spider species, maximizes at very different humidities that matches their foraging habitats. By using high-speed imaging and spreading power law, we find that the glue viscosity varies over 5 orders of magnitude with humidity for each species, yet the viscosity at maximal adhesion for each species is nearly identical, 10(5)-10(6) cP. Many natural systems take advantage of viscosity to improve functional response, but spider glue's humidity responsiveness is a novel adaptation that makes the glue stickiest in each species' preferred habitat. This tuning is achieved by a combination of proteins and hygroscopic organic salts that determines water uptake in the glue. We therefore anticipate that manipulation of polymer-salts interaction to control viscosity can provide a simple mechanism to design humidity responsive smart adhesives.

  15. Characteristics of the adhesive determinants of Lactobacillus fermentum 104.

    PubMed Central

    Henriksson, A; Szewzyk, R; Conway, P L

    1991-01-01

    The adhesion of Lactobacillus fermentum 104-R and the variant strain 104-S to porcine gastric squamous epithelium was investigated. An epithelium-specific adhesion was detected for strain 104-S; however, strain 104-R expressed enhanced adhesion capacity to the control surfaces of polystyrene and bovine serum albumin. To characterize the adhesive determinants, the bacterial cells were exposed to various treatments. The adhesion pattern of bacterial cells in buffers of pH values ranging from 2 to 7 was determined. The adhesion of strain 104-S to epithelium was greater in a buffer with a higher pH value. On the other hand, adhesion of strain 104-R to the epithelium was rather unaffected by a change in pH. To the control surfaces of polystyrene or bovine serum albumin, the adhesion of both strains was greatest at pH 2 to 4. Treatment of strain 104-S with metaperiodate did not affect the adhesion to epithelium or polystyrene; however, protease treatment dramatically decreased the adhesion of both strains, thus suggesting that the determinants responsible for the adhesion were proteinaceous. Carbohydrates may be partially involved in the adhesion of 104-R because metaperiodate-treated cells adhered more poorly than control, iodate-treated cells. The adhesion-promoting components are most probably tightly bound to the cell wall, because washing with low-pH buffer (pH 1.2) or sodium dodecyl sulfate had no major effect on the adhesion. PMID:1849714

  16. Thermal Characterization of Epoxy Adhesive by Hotfire Testing

    NASA Technical Reports Server (NTRS)

    Spomer, Ken A.; Haddock, M. Reed; McCool, Alex (Technical Monitor)

    2001-01-01

    This paper describes subscale solid-rocket motor hot-fire testing of epoxy adhesives in flame surface bondlines to evaluate heat-affected depth, char depth and ablation rate. Hot-fire testing is part of an adhesive down-selection program on the Space Shuttle Solid Rocket Motor Nozzle to provide additional confidence in the down-selected adhesives. The current nozzle structural adhesive bond system is being replaced due to obsolescence. Prior to hot-fire testing, adhesives were tested for chemical, physical and mechanical properties, which resulted in the selection of two potential replacement adhesives, Resin Technology Group's TIGA 321 and 3M's EC2615XLW. Hot-fire testing consisted of four forty-pound charge (FPC) motors fabricated in configurations that would allow side-by-side comparison testing of the candidate replacement adhesives with the current RSRM adhesives. Results of the FPC motor testing show that: 1) the phenolic char depths on radial bondlines is approximately the same and vary depending on the position in the blast tube regardless of which adhesive was used, 2) the replacement candidate adhesive char depths are equivalent to the char depths of the current adhesives, 3) the heat-affected depths of the candidate and current adhesives are equivalent, and 4) the ablation rates for both replacement adhesives were equivalent to the current adhesives.

  17. Human climbing with efficiently scaled gecko-inspired dry adhesives.

    PubMed

    Hawkes, Elliot W; Eason, Eric V; Christensen, David L; Cutkosky, Mark R

    2015-01-06

    Since the discovery of the mechanism of adhesion in geckos, many synthetic dry adhesives have been developed with desirable gecko-like properties such as reusability, directionality, self-cleaning ability, rough surface adhesion and high adhesive stress. However, fully exploiting these adhesives in practical applications at different length scales requires efficient scaling (i.e. with little loss in adhesion as area grows). Just as natural gecko adhesives have been used as a benchmark for synthetic materials, so can gecko adhesion systems provide a baseline for scaling efficiency. In the tokay gecko (Gekko gecko), a scaling power law has been reported relating the maximum shear stress σmax to the area A: σmax ∝ A(-1/4). We present a mechanical concept which improves upon the gecko's non-uniform load-sharing and results in a nearly even load distribution over multiple patches of gecko-inspired adhesive. We created a synthetic adhesion system incorporating this concept which shows efficient scaling across four orders of magnitude of area, yielding an improved scaling power law: σmax ∝ A(-1/50). Furthermore, we found that the synthetic adhesion system does not fail catastrophically when a simulated failure is induced on a portion of the adhesive. In a practical demonstration, the synthetic adhesion system enabled a 70 kg human to climb vertical glass with 140 cm(2) of adhesive per hand.

  18. Design and fabrication of gecko-inspired adhesives.

    PubMed

    Jin, Kejia; Tian, Yu; Erickson, Jeffrey S; Puthoff, Jonathan; Autumn, Kellar; Pesika, Noshir S

    2012-04-03

    Recently, there has been significant interest in developing dry adhesives mimicking the gecko adhesive system, which offers several advantages compared to conventional pressure-sensitive adhesives. Specifically, gecko adhesive pads have anisotropic adhesion properties; the adhesive pads (spatulae) stick strongly when sheared in one direction but are non-adherent when sheared in the opposite direction. This anisotropy property is attributed to the complex topography of the array of fine tilted and curved columnar structures (setae) that bear the spatulae. In this study, we present an easy, scalable method, relying on conventional and unconventional techniques, to incorporate tilt in the fabrication of synthetic polymer-based dry adhesives mimicking the gecko adhesive system, which provides anisotropic adhesion properties. We measured the anisotropic adhesion and friction properties of samples with various tilt angles to test the validity of a nanoscale tape-peeling model of spatular function. Consistent with the peel zone model, samples with lower tilt angles yielded larger adhesion forces. The tribological properties of the synthetic arrays were highly anisotropic, reminiscent of the frictional adhesion behavior of gecko setal arrays. When a 60° tilt sample was actuated in the gripping direction, a static adhesion strength of ~1.4 N/cm(2) and a static friction strength of ~5.4 N/cm(2) were obtained. In contrast, when the dry adhesive was actuated in the releasing direction, we measured an initial repulsive normal force and negligible friction.

  19. Biologically Inspired Mushroom-Shaped Adhesive Microstructures

    NASA Astrophysics Data System (ADS)

    Heepe, Lars; Gorb, Stanislav N.

    2014-07-01

    Adhesion is a fundamental phenomenon with great importance in technology, in our everyday life, and in nature. In this article, we review physical interactions that resist the separation of two solids in contact. By using examples of biological attachment systems, we summarize and categorize various principles that contribute to the so-called gecko effect. Emphasis is placed on the contact geometry and in particular on the mushroom-shaped geometry, which is observed in long-term biological adhesive systems. Furthermore, we report on artificial model systems with this bio-inspired geometry and demonstrate that surface microstructures with this geometry are promising candidates for technical applications, in which repeatable, reversible, and residue-free adhesion under different environmental conditions—such as air, fluid, and vacuum—is required. Various applications in robotic systems and in industrial pick-and-place processes are discussed.

  20. Water based adhesive primers on aluminum substrates

    SciTech Connect

    Wightman, J.P.; Mori, S.

    1996-12-31

    The number of aluminum alloy bonding applications has been increasing recently in the automobile industry. Primer coating of aluminum substrates is one of the main processes used to promote bond performance. Solvent based organic primers have been used for a long time but environmental regulations now require the substitution of volatile organic compounds (VOC) by alternate materials such as water based adhesive primers. However, the bond strengths obtained with many water based primers are generally lower than for solvent based ones. Water based primers which have some reactive functional groups have been proposed recently but such primers require special treatment. This paper describes a study conducted to optimize bond strength using a water based adhesive as a primer in the adhesive bonding of anodized aluminum.

  1. Optimizing ultrasonic imaging for adhesively bonded plates

    SciTech Connect

    Conboy, Mike; Hart, Scot; Harris-Weiel, David; Meyer, R. L.; Claytor, T. N.

    2004-01-01

    Bonded materials are used in many critical applications, making it important to determine the state of the adhesive during service or aging. It is also of importance, in many cases, to determine if the adhesive has uniformly and completely covered the area to be joined. Through dual transducer scanning, focused and unfocused transducers, and immersion scanning, the uniformity and adherence of a visco-elastic material can be evaluated. In this report, ultrasonic scanning parameters will be optimized experimentally with guidance from simulation tools including Wave 2000 pro and Imagine 3D. We explored optimizing the contrast ratio by varying the interrogation frequency and also by adjusting the distance between the transducer and bond line. An improvement in contrast should also increase the ability to detect differences in compositions and viscosity of the bonded layer. By maximizing the contrast the quality of the visco-elastic bond can be determined, and imperfections detected before adhesive failure.

  2. Adhesion assessment of copper thin films

    SciTech Connect

    Kriese, M.D.; Gerberich, W.W.; Moody, N.R.

    1997-06-01

    Nano-indentation testing has been used to quantitatively assess the adhesion of thin copper films, sputtered to thicknesses of 150 nm to 1500 nm. Copper films of low residual stress were deposited via RF diode cathode sputtering onto SiO{sub 2}/Si substrates. Overlayers of DC magnetron sputtered tungsten, 850 nm thick with high residual stress, were additionally used to provide a driving force for delamination. All films tested exhibited buckle-driven delamination, from which the interfacial toughness was estimated to be 0.2 - 2 J/m{sup 2}, which is comparable to the thermodynamic work of adhesion. The use of an overlayer requires extensions of existing models, but otherwise does not change the interfacial adhesion, allowing measurements of films that would not otherwise delaminate.

  3. Laparoscopic Management of Adhesive Small Bowel Obstruction

    PubMed Central

    Konjic, Ferid; Idrizovic, Enes; Hasukic, Ismar; Jahic, Alen

    2016-01-01

    Introduction: Adhesions are the reason for bowel obstruction in 80% of the cases. In well selected patients the adhesive ileus laparoscopic treatment has multiple advantages which include the shorter hospitalization period, earlier food taking, and less postoperative morbidity rate. Case report: Here we have a patient in the age of 35 hospitalized at the clinic due to occlusive symptoms. Two years before an opened appendectomy had been performed on him. He underwent the treatment of exploration laparoscopy and laparoscopic adhesiolysis. Dilated small bowel loops connected with the anterior abdominal wall in the ileocecal region by adhesions were found intraoperatively and then resected harmonically with scalpel. One strangulation around which a small bowel loop was wrapped around was found and dissected. Postoperative course was normal. PMID:27041815

  4. Optimizing Scale Adhesion on Single Crystal Superalloys

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Pint, Bruce A.

    2000-01-01

    To improve scale adhesion, single crystal superalloys have been desulfurized to levels below 1 ppmw by hydrogen annealing. A transition to fully adherent behavior has been shown to occur at a sulfur level of about 0.2 ppmw, as demonstrated for PWA 1480, PWA 1484, and Rene N5 single crystal superalloys in 1100-1150 C cyclic oxidation tests up to 2000 h. Small additions of yttrium (15 ppmw) also have been effective in producing adhesion for sulfur contents of about 5 ppmw. Thus the critical Y/S ratio required for adhesion was on the order of 3-to-1 by weight (1-to-1 atomic), in agreement with values estimated from solubility products for yttrium sulfides. While hydrogen annealing greatly improved an undoped alloy, yielding <= 0.01 ppmw S, it also produced benefits for Y-doped alloys without measurably reducing the sulfur content.

  5. Adhesive capsulitis of the hip: a review.

    PubMed

    Looney, Colin G; Raynor, Brett; Lowe, Rebecca

    2013-12-01

    Adhesive capsulitis of the hip (ACH) is a rare clinical entity. Similar to adhesive capsulitis of the shoulder, ACH is characterized by a painful decrease in active and passive range of motion as synovial inflammation in the acute stages of the disease progresses to capsular fibrosis in the chronic stages. Once other diagnoses have been ruled out, management of ACH is tailored to reduce inflammation in the acute stages with NSAIDs, intra-articular steroid injections, and targeted physical therapy while biomechanical dysfunction in the spine, hip, sacroiliac joint, or lower limb joints is addressed. In chronic stages of the disease, intervention should focus on decreasing the progression of fibrotic changes and regaining range of motion through aggressive physical therapy. Interventions described for chronic ACH include manipulation under anesthesia; pressure dilatation; and open or arthroscopic synovectomy, lysis of adhesions, and capsular release. Surgical intervention should be considered only after failure of a minimum 3-month course of nonsurgical treatment.

  6. High-Temperature Adhesive Strain Gage Developed

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Roberts, Gary D.

    1997-01-01

    Researchers at the NASA Lewis Research Center have developed a unique strain gage and adhesive system for measuring the mechanical properties of polymers and polymer composites at elevated temperatures. This system overcomes some of the problems encountered in using commercial strain gages and adhesives. For example, typical commercial strain gage adhesives require a postcure at temperatures substantially higher than the maximum test temperature. The exposure of the specimen to this temperature may affect subsequent results, and in some cases may be higher than the glass-transition temperature of the polymer. In addition, although typical commercial strain gages can be used for short times at temperatures up to 370 C, their long-term use is limited to 230 C. This precludes their use for testing some high-temperature polyimides near their maximum temperature capability. Lewis' strain gage and adhesive system consists of a nonencapsulated, unbacked gage grid that is bonded directly to the polymer after the specimen has been cured but prior to the normal postcure cycle. The gage is applied with an adhesive specially formulated to cure under the specimen postcure conditions. Special handling, mounting, and electrical connection procedures were developed, and a fixture was designed to calibrate each strain gage after it was applied to a specimen. A variety of tests was conducted to determine the performance characteristics of the gages at elevated temperatures on PMR-15 neat resin and titanium specimens. For these tests, which included static tension, thermal exposure, and creep tests, the gage and adhesive system performed within normal strain gage specifications at 315 C. An example of the performance characteristics of the gage can be seen in the figure, which compares the strain gage measurement on a polyimide specimen at 315 C with an extensometer measurement.

  7. Molecular mechanics of mussel adhesion proteins

    NASA Astrophysics Data System (ADS)

    Qin, Zhao; Buehler, Markus J.

    2014-01-01

    Mussel foot protein (mfp), a natural glue produced by marine mussel, is an intriguing material because of its superior ability for adhesion in various environments. For example, a very small amount of this material is sufficient to affix a mussel to a substrate in water, providing structural support under extreme forces caused by the dynamic effects of waves. Towards a more complete understanding of its strength and underwater workability, it is necessary to understand the microscropic mechanisms by which the protein structure interacts with various substrates. However, none of the mussel proteins' structure is known, preventing us from directly using atomistic modeling to probe their structural and mechanical properties. Here we use an advanced molecular sampling technique to identify the molecular structures of two mussel foot proteins (mfp-3 and mfp-5) and use those structures to study their mechanics of adhesion, which is then incorporated into a continuum model. We calculate the adhesion energy of the mussel foot protein on a silica substrate, compute the adhesion strength based on results obtained from molecular modeling, and compare with experimental data. Our results show good agreement with experimental measurements, which validates the multiscale model. We find that the molecular structure of the folded mussel foot protein (ultimately defined by its genetic sequence) favors strong adhesion to substrates, where L-3,4-dihydroxyphenylalanine (or DOPA) protein subunits work in a cooperative manner to enhance adhesion. Our experimental data suggests a peak attachment force of 0.4±0.1 N, which compares favorably with the prediction from the multiscale model of Fc=0.21-0.33 N. The principles learnt from those results could guide the fabrication of new interfacial materials (e.g. composites) to integrate organic with inorganic surfaces in an effective manner.

  8. Method of measuring metal coating adhesion

    DOEpatents

    Roper, John R.

    1985-01-01

    A method for measuring metal coating adhesion to a substrate material comprising the steps of preparing a test coupon of substrate material having the metal coating applied to one surface thereof, applying a second metal coating of gold or silver to opposite surfaces of the test coupon by hot hollow cathode process, applying a coating to one end of each of two pulling rod members, joining the coated ends of the pulling rod members to said opposite coated surfaces of the test coupon by a solid state bonding technique and finally applying instrumented static tensile loading to the pulling rod members until fracture of the metal coating adhesion to the substrate material occurs.

  9. Addition polyimide adhesives containing various end groups

    NASA Technical Reports Server (NTRS)

    Saint Clair, A. K.; Saint Clair, T. L.

    1982-01-01

    Addition polyimode oligomers have been synthesized from 3,3 prime, 4,4 prime-benzophenone tetracarboxylic acid dianhydride and 3,3 prime-methylenedianiline using a variety of latent crosslinking groups as end-caps. The nominal 1300 molecular weight imide prepolymers were isolated and characterized for solubility in amide, chlorinated and ether solvents, melt-flow and cure properties, glass transition temperature, and thermal stability on heating in an air atmosphere. Adhesive strengths of the polyimides were obtained both at ambient and elevated temperatures before and after aging at 232 C. Properties of the novel addition polyimides were compared to a known nadic end-capped adhesive, LARC-13.

  10. Effects of military environments on optical adhesives

    NASA Astrophysics Data System (ADS)

    Krevor, David H.; Vazirani, Hargovind N.; Xu, Antai

    1993-09-01

    The military environment imposes harsh conditions on adhesives. These conditions differ both qualitatively and quantitatively from typical civilian environments. Military systems must withstand exposure to moisture, temperature extremes, sunlight/ultraviolet radiation and other climatic stresses that are far in excess of what would be expected for commercial applications. Additionally, civilian products rarely consider issues such as fungus susceptibility, resistance to jet fuels and de-icing solvents, or resistance to chemical warfare agents and their decontaminants. The effect of military environments on both the optical and mechanical properties of optical adhesives are discussed for avionic display applications.

  11. The Mechanisms of Adhesion of Enteromorpha Clathrata.

    DTIC Science & Technology

    1982-08-24

    the mobilities at different values of pH: pH 2-3 Glycine hydrochloride -glycine pH 4-5 Acetic acid-sodium acetate ,. . .. .,:,.o.-,-. -o...wall, while glucose was much higher in the cell wall. Glucosamine was found only in the cell wall. The chemical analysis of the cell wall of E...Adhesive Material. Fucose Galactose Glucose Glucosamine Total • pg pg pg ,pg pg Adhesive 13.78 1.597 87.741 103.1 Cell Wall 7.5 0.73 95.7 7.5 110.7 ’ .4

  12. Familial adhesive arachnoiditis associated with syringomyelia.

    PubMed

    Pasoglou, V; Janin, N; Tebache, M; Tegos, T J; Born, J D; Collignon, L

    2014-06-01

    Adhesive arachnoiditis is a rare condition, often complicated by syringomyelia. This pathologic entity is usually associated with prior spinal surgery, spinal inflammation or infection, and hemorrhage. The usual symptoms of arachnoiditis are pain, paresthesia, and weakness of the low extremities due to the nerve entrapment. A few cases have had no obvious etiology. Previous studies have reported one family with multiple cases of adhesive arachnoiditis. We report a second family of Belgian origin with multiple cases of arachnoiditis and secondary syringomyelia in the affected individuals.

  13. Method of measuring metal coating adhesion

    DOEpatents

    Roper, J.R.

    A method for measuring metal coating adhesion to a substrate material comprising the steps of preparing a test coupon of substrate material having the metal coating applied to one surface thereof, applying a second metal coating of gold or silver to opposite surfaces of the test coupon by hot hollow cathode process, applying a coating to one end of each of two pulling rod members, joining the coated ends of the pulling rod members to said opposite coated surfaces of the test coupon by a solid state bonding technique and finally applying instrumented static tensile loading to the pulling rod members until fracture of the metal coating adhesion to the substrate material occurs.

  14. Biologically Inspired Polymer Micro-Patterned Adhesives

    DTIC Science & Technology

    2008-11-01

    SEM image showing smooth adhesion pad at end of tibia in aphid Megoura viciae 12 2. Droplets left on glass slide from tarsal footprint of beetle...or they can be just a smooth pad as in cockroaches, aphids , and ants (see Figure 1b).3 •*,««, -«" Figure 1a. Scanning electron microscope (SEM...image showing smooth adhesion pad (p) at end of tibia in aphid Megoura viciae. [ta = tarsus, ti = tibia. Scale bar = 20 microns (adapted from Lees

  15. Beetle adhesive hairs differ in stiffness and stickiness: in vivo adhesion measurements on individual setae

    NASA Astrophysics Data System (ADS)

    Bullock, James M. R.; Federle, Walter

    2011-05-01

    Leaf beetles are able to climb on smooth and rough surfaces using arrays of micron-sized adhesive hairs (setae) of varying morphology. We report the first in vivo adhesive force measurements of individual setae in the beetle Gastrophysa viridula, using a smooth polystyrene substrate attached to a glass capillary micro-cantilever. The beetles possess three distinct adhesive pads on each leg which differ in function and setal morphology. Visualisation of pull-offs allowed forces to be measured for each tarsal hair type. Male discoidal hairs adhered with the highest forces (919 ± 104 nN, mean ± SE), followed by spatulate (582 ± 59 nN) and pointed (127 ± 19 nN) hairs. Discoidal hairs were stiffer in the normal direction (0.693 ± 0.111 N m-1) than spatulate (0.364 ± 0.039 N m-1) or pointed (0.192 ± 0.044 N m-1) hairs. The greater adhesion on smooth surfaces and the higher stability of discoidal hairs help male beetles to achieve strong adhesion on the elytra of females during copulation. A comparison of pull-off forces measured for single setae and whole pads (arrays) revealed comparable levels of adhesive stress. This suggests that beetles are able to achieve equal load sharing across their adhesive pads so that detachment through peeling is prevented.

  16. Use of fibrin adhesive to reduce post-surgical adhesion reformation in rabbits.

    PubMed

    Osada, H; Minai, M; Yoshida, T; Satoh, K

    1999-01-01

    Following surgery on fallopian tubes, the development of adhesions is a natural consequence of wound healing and may result in infertility. Using a rabbit model, we evaluated the anti-adhesive properties of a sponge-like equine collagen sheet (TachoComb), which is coated on one side with human fibrinogen and bovine thrombin. TachoComb is applied by affixing the sheet over the area of perforation or bleeding and acts as a haemostatic agent, capable of sealing perforations to prevent leakage. In our rabbit model, adhesions were induced by mechanical and chemical irritants during laparotomy. After a 1-month recovery period, adhesions were lysed using microsurgical techniques and TachoComb, or physiological saline applied. Evaluation of adhesion reformation was determined after a minimum of 10 days. TachoComb significantly reduced the area of adhesion reformation compared with rabbits treated using physiological saline only. Our study demonstrated that TachoComb is effective not only as a haemostatic agent, but is also capable of reducing adhesion reformation.

  17. Rheological studies on pressure-sensitive silicone adhesives and drug-in-adhesive layers as a means to characterise adhesive performance.

    PubMed

    Ho, Kwong Yat; Dodou, Kalliopi

    2007-03-21

    Pressure-sensitive adhesives are viscoelastic polymers used in the formulation of transdermal patches that allow attachment of a patch onto the skin. Established criteria exist that correlate viscoelastic parameters with adhesive performance. In this study, fulfillment of the adhesive performance criteria was examined using two silicone adhesives with different tack properties. The viscoelastic parameters of high and low tack silicone adhesives (BIO-PSA High Tack 7-4302 and BIO-PSA Low Tack 7-4102) were determined and compared with the criteria described by Chu and Dahlquist. Drug-in-adhesive layers were prepared using the high tack adhesive combined with nortriptyline HCl or paracetamol. The effect of drug addition on the viscoelastic properties of the adhesive was examined. The high tack adhesive showed congruence with the established criteria although with a modified range of viscoelastic moduli to that described by Chu. Examination of the low tack adhesive showed that it did not possess the appropriate viscoelastic properties for bonding onto the skin. The addition of the drugs into the high tack adhesive caused a concentration-dependent increase in its cohesive strength. This effect was independent of the physicochemical properties of the drugs tested.

  18. Adhesion tilt-tolerance in bio-inspired mushroom-shaped adhesive microstructure

    NASA Astrophysics Data System (ADS)

    Heepe, Lars; Carbone, Giuseppe; Pierro, Elena; Kovalev, Alexander E.; Gorb, Stanislav N.

    2014-01-01

    We studied experimentally and theoretically the effect of different tilt angles on the adhesion of mushroom-shaped adhesive microstructures. The marginal measured influence of tilting on pull-off forces is quantitatively well confirmed by numerical and theoretical calculations and was shown to be a direct consequence of an optimized stress distribution. In addition, the presence of a joint-like narrowing under the contact elements, as found in some biological attachment systems, was shown to further contribute to the tilt-tolerance. The results obtained allow us to explain the advantage of the widely observed mushroom-shaped contact geometry in nature for long-term and permanent adhesion.

  19. Superhydrophobic (low adhesion) and parahydrophobic (high adhesion) surfaces with micro/nanostructures or nanofilaments.

    PubMed

    Diouf, Alioune; Darmanin, Thierry; Dieng, Samba Yandé; Guittard, Frédéric

    2015-09-01

    Controlling the water adhesion is extremely important for various applications such as for water harvesting. Here, superhydrophobic (low adhesion) and parahydrophobic (high adhesion) substrates are both obtained from hydrophilic polymers. We show in the work that a judicious choice in the monomer structure used for electropolymerization can lead to these two properties. Using a phenyl group, parahydrophobic properties are reached due to the formation of nanofilaments. By contrast, using a naphthalene or a biphenyl group, superhydrophobic properties are obtained due the formation of both micro- and nanostructures.

  20. Guest editorial, special issue on biobased adhesives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This article is a preface for a special issue that showcases significant developments on adhesives made with biorenewable materials, such as agricultural crops (soybean, corn), plant extractives (bark, tannins), and marine sources (mussels). This collection of pioneering studies and reviews on bioba...

  1. Clinical experience with cyanoacrylate tissue adhesive.

    PubMed

    Moschos, M; Droutsas, D; Boussalis, P; Tsioulias, G

    In this paper 385 cases treated with cyanoacrylate tissue adhesive during the years 1980-1995 are studied. The indications, outcomes and complications of cyanoacrylate adhesive are investigated and the results are analysed. It is encouraging that except for three cases of ocular hypotony and two cases of microbial infection no other complications occurred. Even in desperate cases with corneal perforation greater than 3 mm and ocular infection, enucleation was avoided. The early use of a bandage contact lens, inserted just after the glue application and the coverage with topical antibiotics switched every 15 days until the removal of the glue, may explain the small incidence of infection. Our experience from the use of cyanoacrylate tissue adhesive in cases with corneal perforation greater than 3 mm is very encouraging. In these cases a running 10.0 nylon suture was used to create a reticulum over the space of the corneal perforation upon which the glue was applied. The use of cyanoacrylate tissue adhesive offers to the clinician a safe technique for healing corneal wounds that avoids tectonic penetrating keratoplasty with its associated complications.

  2. Adhesion of D. discoideum on Hydrophobic Substrate

    NASA Astrophysics Data System (ADS)

    Flanders, Bret; Ploscariu, Nicoleta

    2015-03-01

    Adhesion by amoeboid cells, such as D. discoideum, is poorly understood but critical for other behaviors such as phagocytosis and migration. Furthermore, both leucocytes and breast cancer cells employ the amoeboid mode of movement at various points in their life-cycles. Hence, improved knowledge of amoeboid adhesion may lead to be new strategies for controlling other important cellular processes. This study regards adhesion by D. discoideum on silanized glass substrates. Reflection interference contrast microscopy is used in conjunction with other methods to determine the contact angle, cell-medium interfacial energy, and adhesion energy of these cells. The contact angle of individual cells settling under gravity onto a substrate is observed to increase as the size of the contact patch increases. This behavior occurs on slower time-scales than expected for the settling of inert vesicles. The implications of this observation on the nature of the underlying forces will be discussed. This work was supported in part by NSF Grant PHY-646966.

  3. 21 CFR 878.4010 - Tissue adhesive.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Tissue adhesive. 878.4010 Section 878.4010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... intended for use in the embolization of brain arteriovenous malformation or for use in ophthalmic...

  4. 21 CFR 878.4010 - Tissue adhesive.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Tissue adhesive. 878.4010 Section 878.4010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... intended for use in the embolization of brain arteriovenous malformation or for use in ophthalmic...

  5. 21 CFR 878.4010 - Tissue adhesive.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Tissue adhesive. 878.4010 Section 878.4010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... intended for use in the embolization of brain arteriovenous malformation or for use in ophthalmic...

  6. 21 CFR 878.4010 - Tissue adhesive.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Tissue adhesive. 878.4010 Section 878.4010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... intended for use in the embolization of brain arteriovenous malformation or for use in ophthalmic...

  7. Performance of thermal adhesives in forced convection

    NASA Technical Reports Server (NTRS)

    Kundu, Nikhil K.

    1993-01-01

    Cooling is critical for the life and performance of electronic equipment. In most cases cooling may be achieved by natural convection but forced convection may be necessary for high wattage applications. Use of conventional type heat sinks may not be feasible from the viewpoint of specific applications and the costs involved. In a heat sink, fins can be attached to the well by ultrasonic welding, by soldering, or with a number of industrially available thermal adhesives. In this paper, the author investigates the heat transfer characteristics of several adhesives and compares them with ultrasonic welding and theoretically calculated values. This experiment was conducted in an air flow chamber. Heat was generated by using heaters mounted on the well. Thermstrate foil, Uniset A401, and Aremco 571 adhesives were tested along with an ultrasonically welded sample. Ultrasonic welding performed far better than the adhesives and Thermstrate foil. This type of experiment can be adapted for a laboratory exercise in an upper level heat transfer course. It gives students an exposure to industrial applications that help them appreciate the importance of the course material.

  8. An oxidase road to platelet adhesion.

    PubMed

    Krause, Diane S

    2016-03-17

    Platelet adhesion to collagen via collagen receptors is an important part of thrombosis. In this issue of Blood, Matsuura et al identify collagen receptors as previously unrecognized targets of the extracellular enzyme lysyl oxidase (LOX), the level of which is increased in myeloproliferative neoplasms (MPNs) and other conditions associated with pathological thromboses.

  9. Nondestructive Evaluation of Adhesively Bonded Joints

    NASA Technical Reports Server (NTRS)

    Nayeb-Hashemi, Hamid; Rossettos, J. N.

    1997-01-01

    The final report consists of 5 published papers in referred journals and a technical letter to the technical monitor. These papers include the following: (1) Comparison of the effects of debonds and voids in adhesive; (2) On the peak shear stresses in adhesive joints with voids; (3) Nondestructive evaluation of adhesively bonded joints by acousto-ultrasonic technique and acoustic emission; (4) Multiaxial fatigue life evaluation of tubular adhesively bonded joints; (5) Theoretical and experimental evaluation of the bond strength under peeling loads. The letter outlines the progress of the research. Also included is preliminary information on the study of nondestructive evaluation of composite materials subjected to localized heat damage. The investigators studied the effects of localized heat on unidirectional fiber glass epoxy composite panels. Specimens of the fiber glass epoxy composites were subjected to 400 C heat for varying lengths of time. The specimens were subjected to nondestructive tests. The specimens were then pulled to their failure and acoustic emission of these specimens were measured. The analysis of the data was continuing as of the writing of the letter, and includes a finite element stress analysis of the problem.

  10. Advanced Fast Curing Adhesives for Adverse Conditions

    DTIC Science & Technology

    2007-07-01

    set of battle damage repair adhesives include Belzona 2311 elastomer , Belzona 1221 super metal, and Belzona metal plug, which are very fast curing...resin, and dinonylphenol (10). Marine use A-788 Splash Zone epoxy- polyamide mastic from Z Spar, Los Angeles, CA was used for testing (11). The

  11. The role of material properties in adhesion

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1984-01-01

    When two solid surfaces are brought into contact strong adhesive bond forces can develop between the materials. The magnitude of the forces will depend upon the state of the surfaces, cleanliness and the fundamental properties of the two solids, both surface and bulk. Adhesion between solids is addressed from a theoretical consideration of the electronic nature of the surfaces and experimentally relating bond forces to the nature of the interface resulting from solid state contact. Surface properties correlated with adhesion include, atomic or molecular orientation, reconstruction and segregation as well as the chemistry of the surface specie. Where dissimilar solids are in contact the contribution of each is considered as is the role of their interactive chemistry on bond strength. Bulk properties examined include elastic and plastic behavior in the surficial regions, cohesive binding energies, crystal structure, crystallographic orientation and state. Materials examined with respect to interfacial adhesive interactions include metals, alloys, ceramics, polymers and diamond. They are reviewed both in single and polycrystalline form. The surfaces of the contacting solids are studied both in the atomic or molecularly clean state and in the presence of selected surface contaminants.

  12. Method for making adhesive from biomass

    DOEpatents

    Russell, Janet A.; Riemath, William F.

    1985-01-01

    A method is described for making adhesive from biomass. A liquefaction oil is prepared from lignin-bearing plant material and a phenolic fraction is extracted therefrom. The phenolic fraction is reacted with formaldehyde to yield a phenol-formaldehyde resin.

  13. Inhibition of bacterial adhesion on medical devices.

    PubMed

    Rodrigues, Lígia R

    2011-01-01

    Microbial infections resulting from bacterial adhesion to biomaterial surfaces have been observed on almost all medical devices. Biofilm infections pose a number of clinical challenges due to their resistance to immune defence mechanisms and antimicrobials, and, regardless of the sophistication of the implant, all medical devices are susceptible to microbial colonisation and infection. Research efforts are currently directed towards eliminating or reducing infection of medical devices. Strategies to prevent biofilm formation include physiochemical modification of the biomaterial surface to create anti-adhesive surfaces, incorporation of antimicrobial agents into medical device polymers, mechanical design alternatives, and release of antibiotics. Nevertheless, the success of these alternatives has been modest, mainly due to the various environments into which devices are placed and the diversity of ways in which organisms can colonise surfaces. Biosurfactants have been reported as a promising strategy as they effectively inhibit bacterial adhesion and retard biofilm formation, and are thus potentially useful as a new generation of anti-adhesive and antimicrobial coatings for medical devices.

  14. Discovery of Low Mucus Adhesion Surfaces

    PubMed Central

    Gu, Minghao; Yildiz, Hasan; Carrier, Rebecca; Belfort, Georges

    2014-01-01

    Mucus secretion from the body is ubiquitous and finding materials that resist mucus adhesion is a major technological challenge of medical and consumer import. Here, using a high throughput platform (HTP) with photo-induced graft polymerization, we first rapidly synthesized, screened and tested a library of 55 different surfaces from six functional monomer classes to discover porcine intestinal low mucus adhesion surfaces using a 1 hr static mucus adsorption protocol. From this preliminary screen, two chemistries, a zwitterionic ([2-(acryloyloxy)ethyl] trimethylammonium chloride) and a multiple hydroxyl (N-[tris(hydroxymethyl)methyl]acrylamide) surface, exhibited the significantly low mucus adhesion from a Langmuir-type isotherm when exposed to increasing concentrations of mucus for 24 hr. Apolar or hydrophobic interactions were likely the dominant attractive forces during mucus binding since many polar or hydrophilic monomers reduced mucus adhesion. Hansen solubility parameters were used to illustrate the importance of monomer polarity and hydrogen-bonding in reducing mucus adsorption. For a series of PEG monomers with changing molecular weight from 144 g/mol to 1100 g/mol, we observed an excellent linear correlation (R2 = 0.998) between relative amount adsorbed and the distance from a water point in a specialized HSP plot, emphasizing the role of surface-water interactions for PEG modified surfaces. PMID:23072828

  15. Adhesive contact of randomly rough surfaces

    NASA Astrophysics Data System (ADS)

    Pastewka, Lars; Robbins, Mark

    2012-02-01

    The contact area, stiffness and adhesion between rigid, randomly rough surfaces and elastic substrates is studied using molecular statics and continuum simulations. The surfaces are self-affine with Hurst exponent 0.3 to 0.8 and different short λs and long λL wavelength cutoffs. The rms surface slope and the range and strength of the adhesive potential are also varied. For parameters typical of most solids, the effect of adhesion decreases as the ratio λL/λs increases. In particular, the pull-off force decreases to zero and the area of contact Ac becomes linear in the applied load L. A simple scaling argument is developed that describes the increase in the ratio Ac/L with increasing adhesion and a corresponding increase in the contact stiffness [1]. The argument also predicts a crossover to finite contact area at zero load when surfaces are exceptionally smooth or the ratio of surface tension to bulk modulus is unusually large, as for elastomers. Results that test this prediction will be presented and related to the Maugis-Dugdale [2] theories for individual asperities and the more recent scaling theory of Persson [3]. [1] Akarapu, Sharp, Robbins, Phys. Rev. Lett. 106, 204301 (2011) [2] Maugis, J. Colloid Interface Sci. 150, 243 (1992) [3] Persson, Phys. Rev. Lett. 74, 75420 (2006)

  16. High-temperature adhesives for polyimide films

    NASA Technical Reports Server (NTRS)

    St. Clair, A. K.; St. Clair, T. L.; Slemp, W. S.

    1979-01-01

    Linear condensation polyimides which are high-temperature polymers show promise as adhesives which form flexible film coatings compatible with polyimide films. Materials are advantageous since they can be supplied as flexible tape, already B-staged and ready for bonding.

  17. Wood adhesives containing proteins and carbohydrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In recent years there has been resurgent interest in using biopolymers as sustainable and environmentally friendly ingredients in wood adhesive formulations. Among them, proteins and carbohydrates are the most commonly used. In this chapter, an overview is given of protein-based and carbohydrate-...

  18. Method for making adhesive from biomass

    DOEpatents

    Russell, J.A.; Riemath, W.F.

    1984-03-30

    A method is described for making adhesive from biomass. A liquefaction oil is prepared from lignin-bearing plant material and a phenolic fraction is extracted therefrom. The phenolic fraction is reacted with formaldehyde to yield a phenol-formaldehyde resin. 2 figures.

  19. Reactive Nanocomposites for Controllable Adhesive Debonding

    DTIC Science & Technology

    2011-08-01

    noncontact debond initiations. It is also noted that the RNC provides the quickest debond found in published literature. 2. Nanocomposite Debond...With paste adhesives, the pressure is applied uniformly, and excess resin in the bond line is forced out of the interfacial area to the thickness

  20. Nitrogen starvation affects bacterial adhesion to soil

    PubMed Central

    Borges, Maria Tereza; Nascimento, Antônio Galvão; Rocha, Ulisses Nunes; Tótola, Marcos Rogério

    2008-01-01

    One of the main factors limiting the bioremediation of subsoil environments based on bioaugmentation is the transport of selected microorganisms to the contaminated zones. The characterization of the physiological responses of the inoculated microorganisms to starvation, especially the evaluation of characteristics that affect the adhesion of the cells to soil particles, is fundamental to anticipate the success or failure of bioaugmentation. The objective of this study was to investigate the effect of nitrogen starvation on cell surface hydrophobicity and cell adhesion to soil particles by bacterial strains previously characterized as able to use benzene, toluene or xilenes as carbon and energy sources. The strains LBBMA 18-T (non-identified), Arthrobacter aurescens LBBMA 98, Arthrobacter oxydans LBBMA 201, and Klebsiella sp. LBBMA 204–1 were used in the experiments. Cultivation of the cells in nitrogen-deficient medium caused a significant reduction of the adhesion to soil particles by all the four strains. Nitrogen starvation also reduced significantly the strength of cell adhesion to the soil particles, except for Klebsiella sp. LBBMA 204–1. Two of the four strains showed significant reduction in cell surface hydrophobicity. It is inferred that the efficiency of bacterial transport through soils might be potentially increased by nitrogen starvation. PMID:24031246

  1. High Temperature Adhesives for Bonding Kapton

    NASA Technical Reports Server (NTRS)

    Stclair, A. K.; Slemp, W. S.; Stclair, T. L.

    1978-01-01

    Experimental polyimide resins were developed and evaluated as potential high temperature adhesives for bonding Kapton polyimide film. Lap shear strengths of Kapton/Kapton bonds were obtained as a function of test temperature, adherend thickness, and long term aging at 575K (575 F) in vacuum. Glass transition temperatures of the polyimide/Kapton bondlines were monitored by thermomechanical analysis.

  2. Underwater Adhesives Retrofit Pipelines with Advanced Sensors

    NASA Technical Reports Server (NTRS)

    2015-01-01

    Houston-based Astro Technology Inc. used a partnership with Johnson Space Center to pioneer an advanced fiber-optic monitoring system for offshore oil pipelines. The company's underwater adhesives allow it to retrofit older deepwater systems in order to measure pressure, temperature, strain, and flow properties, giving energy companies crucial data in real time and significantly decreasing the risk of a catastrophe.

  3. Discovery of low mucus adhesion surfaces.

    PubMed

    Gu, Minghao; Yildiz, Hasan; Carrier, Rebecca; Belfort, Georges

    2013-02-01

    Mucus secretion from the body is ubiquitous, and finding materials that resist mucus adhesion is a major technological challenge. Here, using a high throughput platform with photo-induced graft polymerization, we first rapidly synthesized, screened and tested a library of 55 different surfaces from six functional monomer classes to discover porcine intestinal low mucus adhesion surfaces using a 1h static mucus adsorption protocol. From this preliminary screen, two chemistries, a zwitterionic ([2-(acryloyloxy)ethyl] trimethylammonium chloride) and a multiple hydroxyl (N-[tris(hydroxymethyl)methyl]acrylamide) surface, exhibited significantly low mucus adhesion from a Langmuir-type isotherm when exposed to increasing concentrations of mucus for 24 h. Apolar or hydrophobic interactions were likely the dominant attractive forces during mucus binding since many polar or hydrophilic monomers reduced mucus adhesion. Hansen solubility parameters were used to illustrate the importance of monomer polarity and hydrogen bonding in reducing mucus adsorption. For a series of polyethylene glycol (PEG) monomers with changing molecular weight from 144 g mol⁻¹ to 1100 g mol⁻¹, we observed an excellent linear correlation (R²=0.998) between relative amount adsorbed and the distance from a water point in a specialized Hansen solubility parameter plot, emphasizing the role of surface-water interactions for PEG modified surfaces.

  4. Flowmeter determines mix ratio for viscous adhesives

    NASA Technical Reports Server (NTRS)

    Lemons, C. R.

    1967-01-01

    Flowmeter determines mix ratio for continuous flow mixing machine used to produce an adhesive from a high viscosity resin and aliphatic amine hardener pumped through separate lines to a rotary blender. The flowmeter uses strain gages in the two flow paths and monitors their outputs with appropriate instrumentation.

  5. Si/Cu Interface Structure and Adhesion

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Gang; Smith, John

    2006-03-01

    An ab initio investigation of the Si(111)/Cu(111) interfacial atomic structure and adhesion is reported [1]. Misfit dislocations appear naturally, as do hcp interfacial silicide phases that vary with temperature. The silicides form in the interface even at relatively low temperatures. These results are consistent with available experimental data. [1] Xiao-Gang Wang, John Smith, Physical Review Letters 95, 156102 (2005).

  6. Adhesion of Antireflective Coatings in Multijunction Photovoltaics: Preprint

    SciTech Connect

    Brock, Ryan; Dauskardt, Reinhold H.; Miller, David C.

    2016-06-16

    The development of a new composite dual cantilever beam (cDCB) thin-film adhesion testing method is reported, which allows the measurement of adhesion on the fragile thin substrates used in multijunction photovoltaics. We address the adhesion of several antireflective coating systems on multijunction cells. By varying interface chemistry and morphology, we demonstrate the ensuing effects on adhesion and help to develop an understanding of how high adhesion can be achieved, as adhesion values ranging from 0.5 J/m2 to 10 J/m2 were measured. Damp Heat (85 degrees C/85% RH) was used to invoke degradation of interfacial adhesion. We show that even with germanium substrates that fracture easily, quantitative measurements of adhesion can still be made at high test yield. The cDCB test is discussed as an important new methodology, which can be broadly applied to any system that makes use of thin, brittle, or otherwise fragile substrates.

  7. Piezoelectric inkjet printing of medical adhesives and sealants

    NASA Astrophysics Data System (ADS)

    Boehm, Ryan D.; Gittard, Shaun D.; Byrne, Jacqueline M. H.; Doraiswamy, Anand; Wilker, Jonathan J.; Dunaway, Timothy M.; Crombez, Rene; Shen, Weidian; Lee, Yuan-Shin; Narayan, Roger J.

    2010-07-01

    Piezoelectric inkjet printing is a noncontact process that enables microscale processing of biological materials. In this research summary, the use of piezoelectric inkjet printing for patterning medical adhesives and sealants, including a two-component polyethylene glycol hydrogel-based medical sealant, an N-butyl cyanoacrylate tissue adhesive, and a mussel adhesive protein biological adhesive, is described The effect of Fe(III) on mussel adhesive protein structure was evaluated by means of atomic force microscopy. The ability to process microscale patterns of medical sealants and adhesives will provide an improvement in tissue joining, including enhanced tissue integrity, reduced bond lines, and decreased adhesive toxicity. Piezoelectric inkjet deposition of medical adhesives and sealants may be used in wound closure, fracture fixation, and microscale vascular surgery.

  8. Abdominal adhesions in laparoscopic hernia repair. An experimental study.

    PubMed

    Eller, R; Twaddell, C; Poulos, E; Jenevein, E; McIntire, D; Russell, S

    1994-03-01

    Laparoscopic herniorrhaphy is becoming an increasingly common procedure. The possible creation of intraperitoneal adhesions during laparoscopic herniorrhaphy has not been examined. For the transperitoneal hernia repair to be an acceptable option, the hypothesis that this approach will incite significant adhesions must be rejected. To test this hypothesis, 21 pigs underwent laparoscopic herniorrhaphy using a standard procedure with the implantation of a polypropylene mesh graft on one side while a sham procedure was performed on the other. These animals were later examined laparoscopically for adhesion formation and the condition of the graft. None of the 21 animals developed adhesions to the trocar sites, 12 animals developed adhesions to the area of the polypropylene mesh, and 3 developed adhesions to the side of the sham procedure. There were no adhesions involving the small intestine. It is therefore concluded that the hypothesis should be rejected and that laparoscopic herniorrhaphy does not incite significant adhesions.

  9. Strong, reversible underwater adhesion via gecko-inspired hydrophobic fibers.

    PubMed

    Soltannia, Babak; Sameoto, Dan

    2014-12-24

    Strong, reversible underwater adhesion using gecko-inspired surfaces is achievable through the use of a hydrophobic structural material and does not require surface modification or suction cup effects for this adhesion to be effective. Increased surface energy can aid in dry adhesion in an air environment but strongly degrades wet adhesion via reduction of interfacial energy underwater. A direct comparison of structurally identical but chemically different mushroom shaped fibers shows that strong, reversible adhesion, even in a fully wetted, stable state, is feasible underwater if the structural material of the fibers is hydrophobic and the mating surface is not strongly hydrophilic. The exact adhesion strength will be a function of the underwater interfacial energy between surfaces and the specific failure modes of individual fibers. This underwater adhesion has been calculated to be potentially greater than the dry adhesion for specific combinations of hydrophobic surfaces.

  10. Sliding Adhesion Dynamics of Isolated Gecko Setal Arrays

    NASA Astrophysics Data System (ADS)

    Sponberg, Simon; Autumn, Kellar

    2003-03-01

    The tokay gecko (Gekko gecko) can adhere to nearly any surface through van der Waals interactions of the specialized setae (b-keratin "hairs") of its toe pads. Our recent research has suggested that a gecko is substantially overbuilt for static adhesion requiring as little as 0.03of its theoretical adhesive capacity. We performed the first sliding adhesion experiments on this novel biological adhesive to determine its response to dynamic loading. We isolated arrays of setae and constructed a precision controlled Robo-toe to study sliding effects. Our results indicate that, unlike many typical adhesives, gecko setal arrays exhibit an increased frictional force upon sliding (mk > ms) which further increases with velocity, suggesting that perturbation rejection may be an evolutionary design principle underlying the evolution of the gecko adhesive. We compare these dynamic properties with those of other adhesives and explore the impacts of these results on the design of artificial adhesives.

  11. [Osteosynthesis of mandible by means of solcoseryl dental adhesive paste].

    PubMed

    Zalyan, G; Zalyan, G

    2006-12-01

    The author presents the method of mandibular fractures treatment--osteosynthesis by means of solcoseryl dental adhesive paste. The use of solcoseryl dental adhesive paste accelerates the incarnation of wound and prevents the surgical complications.

  12. Eimeria bovis modulates adhesion molecule gene transcription in and PMN adhesion to infected bovine endothelial cells.

    PubMed

    Hermosilla, Carlos; Zahner, Horst; Taubert, Anja

    2006-04-01

    Eimeria bovis is an important coccidian parasite of cattle causing severe diarrhea in young animals. Its first schizogony takes place in endothelial cells of the ileum resulting in the formation of macroschizonts 14-18 days p.i. This longlasting development suggests a particular immune evasion strategy of the parasite. Here, we analyse early innate immune reactions to E. bovis by determining the adhesion of polymorphonuclear neutrophils (PMN) to infected endothelial cell layers under flow conditions and the transcription of adhesion molecule genes in infected host cells. Bovine umbilical vein endothelial cells (BUVEC) were infected with E. bovis sporozoites. Sporozoites invaded BUVEC within 1h and the first mature macroschizonts occurred 14 days p.i. PMN adhesion was enhanced in E. bovis-infected BUVEC layers as early as 8h p.i.; maximum adhesion occurred 48 h p.i. Increased adhesion rates persisted until the end of the observation period at 14 days p.i. PMN adhered to both infected and uninfected cells within monolayers, suggesting paracrine cell activation. E. bovis infection upregulated the transcription of genes encoding for P-selectin, E-selectin, vascular cellular adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1). Most marked effects concerned E-selectin followed by P-selectin, VCAM-1 and ICAM-1. Increased transcript levels were found beginning 30 min p.i. and maximum values occurred 1-2h p.i. (P-selectin) and 2-4h p.i. (E-selectin, VCAM-1, ICAM-1). By 12-24h p.i. levels had decreased to those of uninfected controls. Tumor necrosis factor alpha (TNFalpha)-induced PMN adhesion was significantly reduced in infected vs. uninfected BUVEC. Eimeria bovis also had suppressive effects on TNFalpha-mediated upregulation of adhesion molecule gene transcription. The data presented here suggest that infection of BUVEC with E. bovis on one hand induces proinflammatory reactions resulting in enhanced PMN adhesion mediated by upregulated adhesion

  13. Surface pretreatments for medical application of adhesion

    PubMed Central

    Erli, Hans J; Marx, Rudolf; Paar, Othmar; Niethard, Fritz U; Weber, Michael; Wirtz, Dieter C

    2003-01-01

    Medical implants and prostheses (artificial hips, tendono- and ligament plasties) usually are multi-component systems that may be machined from one of three material classes: metals, plastics and ceramics. Typically, the body-sided bonding element is bone. The purpose of this contribution is to describe developments carried out to optimize the techniques , connecting prosthesis to bone, to be joined by an adhesive bone cement at their interface. Although bonding of organic polymers to inorganic or organic surfaces and to bone has a long history, there remains a serious obstacle in realizing long-term high-bonding strengths in the in vivo body environment of ever present high humidity. Therefore, different pretreatments, individually adapted to the actual combination of materials, are needed to assure long term adhesive strength and stability against hydrolysis. This pretreatment for metal alloys may be silica layering; for PE-plastics, a specific plasma activation; and for bone, amphiphilic layering systems such that the hydrophilic properties of bone become better adapted to the hydrophobic properties of the bone cement. Amphiphilic layering systems are related to those developed in dentistry for dentine bonding. Specific pretreatment can significantly increase bond strengths, particularly after long term immersion in water under conditions similar to those in the human body. The bond strength between bone and plastic for example can be increased by a factor approaching 50 (pealing work increasing from 30 N/m to 1500 N/m). This review article summarizes the multi-disciplined subject of adhesion and adhesives, considering the technology involved in the formation and mechanical performance of adhesives joints inside the human body. PMID:14561228

  14. Grippers Based on Opposing Van Der Waals Adhesive Pads

    NASA Technical Reports Server (NTRS)

    Parness, Aaron (Inventor); Kennedy, Brett A. (Inventor); Heverly, Matthew C (Inventor); Cutkosky, Mark R. (Inventor); Hawkes, Elliot Wright (Inventor)

    2016-01-01

    Novel gripping structures based on van der Waals adhesive forces are disclosed. Pads covered with fibers can be activated in pairs by opposite forces, thereby enabling control of the adhesive force in an ON or OFF state. Pads can be used in groups, each comprising a group of opposite pads. The adhesive structures enable anchoring forces that can resist adverse forces from different directions. The adhesive structures can be used to enable the operation of robots on surfaces of space vehicles.

  15. Chemical Characterization and Quality Control for an Adhesive.

    DTIC Science & Technology

    ADHESIVES, *IDENTIFICATION, *CHEMICAL ANALYSIS, *QUALITY CONTROL, PHYSICOCHEMICAL PROPERTIES, ACCEPTANCE TESTS, CLASSIFICATION, VIABILITY, TEST METHODS, ANALYTICAL CHEMISTRY, PROCESSING, PRODUCTION CONTROL , AIRCRAFT .

  16. Direct observation of microcavitation in underwater adhesion of mushroom-shaped adhesive microstructure

    PubMed Central

    Kovalev, Alexander E; Gorb, Stanislav N

    2014-01-01

    Summary In this work we report on experiments aimed at testing the cavitation hypothesis [Varenberg, M.; Gorb, S. J. R. Soc., Interface 2008, 5, 383–385] proposed to explain the strong underwater adhesion of mushroom-shaped adhesive microstructures (MSAMSs). For this purpose, we measured the pull-off forces of individual MSAMSs by detaching them from a glass substrate under different wetting conditions and simultaneously video recording the detachment behavior at very high temporal resolution (54,000–100,000 fps). Although microcavitation was observed during the detachment of individual MSAMSs, which was a consequence of water inclusions present at the glass–MSAMS contact interface subjected to negative pressure (tension), the pull-off forces were consistently lower, around 50%, of those measured under ambient conditions. This result supports the assumption that the recently observed strong underwater adhesion of MSAMS is due to an air layer between individual MSAMSs [Kizilkan, E.; Heepe, L.; Gorb, S. N. Underwater adhesion of mushroom-shaped adhesive microstructure: An air-entrapment effect. In Biological and biomimetic adhesives: Challenges and opportunities; Santos, R.; Aldred, N.; Gorb, S. N.; Flammang, P., Eds.; The Royal Society of Chemistry: Cambridge, U.K., 2013; pp 65–71] rather than by cavitation. These results obtained due to the high-speed visualisation of the contact behavior at nanoscale-confined interfaces allow for a microscopic understanding of the underwater adhesion of MSAMSs and may aid in further development of artificial adhesive microstructures for applications in predominantly liquid environments. PMID:24991528

  17. Extreme positive allometry of animal adhesive pads and the size limits of adhesion-based climbing

    PubMed Central

    Labonte, David; Clemente, Christofer J.; Dittrich, Alex; Kuo, Chi-Yun; Crosby, Alfred J.; Irschick, Duncan J.; Federle, Walter

    2016-01-01

    Organismal functions are size-dependent whenever body surfaces supply body volumes. Larger organisms can develop strongly folded internal surfaces for enhanced diffusion, but in many cases areas cannot be folded so that their enlargement is constrained by anatomy, presenting a problem for larger animals. Here, we study the allometry of adhesive pad area in 225 climbing animal species, covering more than seven orders of magnitude in weight. Across all taxa, adhesive pad area showed extreme positive allometry and scaled with weight, implying a 200-fold increase of relative pad area from mites to geckos. However, allometric scaling coefficients for pad area systematically decreased with taxonomic level and were close to isometry when evolutionary history was accounted for, indicating that the substantial anatomical changes required to achieve this increase in relative pad area are limited by phylogenetic constraints. Using a comparative phylogenetic approach, we found that the departure from isometry is almost exclusively caused by large differences in size-corrected pad area between arthropods and vertebrates. To mitigate the expected decrease of weight-specific adhesion within closely related taxa where pad area scaled close to isometry, data for several taxa suggest that the pads’ adhesive strength increased for larger animals. The combination of adjustments in relative pad area for distantly related taxa and changes in adhesive strength for closely related groups helps explain how climbing with adhesive pads has evolved in animals varying over seven orders of magnitude in body weight. Our results illustrate the size limits of adhesion-based climbing, with profound implications for large-scale bio-inspired adhesives. PMID:26787862

  18. Hierarchical macroscopic fibrillar adhesives: in situ study of buckling and adhesion mechanisms on wavy substrates.

    PubMed

    Bauer, Christina T; Kroner, Elmar; Fleck, Norman A; Arzt, Eduard

    2015-10-23

    Nature uses hierarchical fibrillar structures to mediate temporary adhesion to arbitrary substrates. Such structures provide high compliance such that the flat fibril tips can be better positioned with respect to asperities of a wavy rough substrate. We investigated the buckling and adhesion of hierarchically structured adhesives in contact with flat smooth, flat rough and wavy rough substrates. A macroscopic model for the structural adhesive was fabricated by molding polydimethylsiloxane into pillars of diameter in the range of 0.3-4.8 mm, with up to three different hierarchy levels. Both flat-ended and mushroom-shaped hierarchical samples buckled at preloads one quarter that of the single level structures. We explain this behavior by a change in the buckling mode; buckling leads to a loss of contact and diminishes adhesion. Our results indicate that hierarchical structures can have a strong influence on the degree of adhesion on both flat and wavy substrates. Strategies are discussed that achieve highly compliant substrates which adhere to rough substrates.

  19. Temperature Effects on Adhesive Bond Strengths and Modulus for Commonly Used Spacecraft Structural Adhesives

    NASA Technical Reports Server (NTRS)

    Ojeda, Cassandra E.; Oakes, Eric J.; Hill, Jennifer R.; Aldi, Dominic; Forsberg, Gustaf A.

    2011-01-01

    A study was performed to observe how changes in temperature and substrate material affected the strength and modulus of an adhesive bondline. Seven different adhesives commonly used in aerospace bonded structures were tested. Aluminum, titanium and Invar adherends were cleaned and primed, then bonded using the manufacturer's recommendations. Following surface preparation, the coupons were bonded with the adhesives. The single lap shear coupons were then pull tested per ASTM D 1002 Standard Test Method for Apparent Shear Strength of Single- Lap-Joint over a temperature range from -150 deg C up to +150 deg C. The ultimate strength was calculated and the resulting data were converted into B-basis design allowables. Average and Bbasis results were compared. Results obtained using aluminum adherends are reported. The effects of using different adherend materials and temperature were also studied and will be reported in a subsequent paper. Dynamic Mechanical Analysis (DMA) was used to study variations in adhesive modulus with temperature. This work resulted in a highly useful database for comparing adhesive performance over a wide range of temperatures, and has facilitated selection of the appropriate adhesive for spacecraft structure applications.

  20. Alterations in Adhesion, Transport, and Membrane Characteristics in an Adhesion-Deficient Pseudomonad

    PubMed Central

    DeFlaun, M. F.; Oppenheimer, S. R.; Streger, S.; Condee, C. W.; Fletcher, M.

    1999-01-01

    A stable adhesion-deficient mutant of Burkholderia cepacia G4, a soil pseudomonad, was selected in a sand column assay. This mutant (ENV435) was compared to the wild-type strain by examining the adhesion of the organisms to silica sand and their transport through two aquifer sediments that differed in their sand, silt, and clay contents. We compared the longitudinal transport of the wild type and the adhesion mutant to the transport of a conservative chloride tracer in 25-cm-long glass columns. The transport of the wild-type strain was severely retarded compared to the transport of the conservative tracer in a variety of aquifer sediments, while the adhesion mutant and the conservative tracer traveled at similar rates. An intact sediment core study produced similar results; ENV435 was transported at a faster rate and in much greater numbers than G4. The results of hydrophobic interaction chromatography revealed that G4 was significantly more hydrophobic than ENV435, and polyacrylamide gel electrophoresis revealed significant differences in the lipopolysaccharide O-antigens of the adhesion mutant and the wild type. Differences in this cell surface polymer may explain the decreased adhesion of strain ENV435. PMID:9925613

  1. The Talin Head Domain Reinforces Integrin-Mediated Adhesion by Promoting Adhesion Complex Stability and Clustering

    PubMed Central

    Ellis, Stephanie J.; Lostchuck, Emily; Goult, Benjamin T.; Bouaouina, Mohamed; Fairchild, Michael J.; López-Ceballos, Pablo; Calderwood, David A.; Tanentzapf, Guy

    2014-01-01

    Talin serves an essential function during integrin-mediated adhesion in linking integrins to actin via the intracellular adhesion complex. In addition, the N-terminal head domain of talin regulates the affinity of integrins for their ECM-ligands, a process known as inside-out activation. We previously showed that in Drosophila, mutating the integrin binding site in the talin head domain resulted in weakened adhesion to the ECM. Intriguingly, subsequent studies showed that canonical inside-out activation of integrin might not take place in flies. Consistent with this, a mutation in talin that specifically blocks its ability to activate mammalian integrins does not significantly impinge on talin function during fly development. Here, we describe results suggesting that the talin head domain reinforces and stabilizes the integrin adhesion complex by promoting integrin clustering distinct from its ability to support inside-out activation. Specifically, we show that an allele of talin containing a mutation that disrupts intramolecular interactions within the talin head attenuates the assembly and reinforcement of the integrin adhesion complex. Importantly, we provide evidence that this mutation blocks integrin clustering in vivo. We propose that the talin head domain is essential for regulating integrin avidity in Drosophila and that this is crucial for integrin-mediated adhesion during animal development. PMID:25393120

  2. 49 CFR 587.16 - Adhesive bonding procedure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 7 2011-10-01 2011-10-01 false Adhesive bonding procedure. 587.16 Section 587.16... Adhesive bonding procedure. Immediately before bonding, aluminum sheet surfaces to be bonded are thoroughly... the abrading process are removed, as these can adversely affect bonding. The adhesive is applied...

  3. 49 CFR 587.16 - Adhesive bonding procedure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Adhesive bonding procedure. 587.16 Section 587.16... Adhesive bonding procedure. Immediately before bonding, aluminum sheet surfaces to be bonded are thoroughly... the abrading process are removed, as these can adversely affect bonding. The adhesive is applied...

  4. 7 CFR 2902.16 - Adhesive and mastic removers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Adhesive and mastic removers. 2902.16 Section 2902.16... Items § 2902.16 Adhesive and mastic removers. (a) Definition. Solvent products formulated for use in removing asbestos, carpet, and tile mastics as well as adhesive materials, including glue, tape, and...

  5. 49 CFR 587.16 - Adhesive bonding procedure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 7 2012-10-01 2012-10-01 false Adhesive bonding procedure. 587.16 Section 587.16... Adhesive bonding procedure. Immediately before bonding, aluminum sheet surfaces to be bonded are thoroughly... the abrading process are removed, as these can adversely affect bonding. The adhesive is applied...

  6. 7 CFR 3201.16 - Adhesive and mastic removers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Adhesive and mastic removers. 3201.16 Section 3201.16... Designated Items § 3201.16 Adhesive and mastic removers. (a) Definition. Solvent products formulated for use in removing asbestos, carpet, and tile mastics as well as adhesive materials, including glue,...

  7. 7 CFR 2902.16 - Adhesive and mastic removers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 15 2011-01-01 2011-01-01 false Adhesive and mastic removers. 2902.16 Section 2902.16... Items § 2902.16 Adhesive and mastic removers. (a) Definition. Solvent products formulated for use in removing asbestos, carpet, and tile mastics as well as adhesive materials, including glue, tape, and...

  8. 49 CFR 587.16 - Adhesive bonding procedure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 7 2014-10-01 2014-10-01 false Adhesive bonding procedure. 587.16 Section 587.16... Adhesive bonding procedure. Immediately before bonding, aluminum sheet surfaces to be bonded are thoroughly... the abrading process are removed, as these can adversely affect bonding. The adhesive is applied...

  9. 49 CFR 587.16 - Adhesive bonding procedure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 7 2013-10-01 2013-10-01 false Adhesive bonding procedure. 587.16 Section 587.16... Adhesive bonding procedure. Immediately before bonding, aluminum sheet surfaces to be bonded are thoroughly... the abrading process are removed, as these can adversely affect bonding. The adhesive is applied...

  10. 7 CFR 3201.16 - Adhesive and mastic removers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Adhesive and mastic removers. 3201.16 Section 3201.16... Designated Items § 3201.16 Adhesive and mastic removers. (a) Definition. Solvent products formulated for use in removing asbestos, carpet, and tile mastics as well as adhesive materials, including glue,...

  11. 7 CFR 3201.16 - Adhesive and mastic removers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Adhesive and mastic removers. 3201.16 Section 3201.16... Designated Items § 3201.16 Adhesive and mastic removers. (a) Definition. Solvent products formulated for use in removing asbestos, carpet, and tile mastics as well as adhesive materials, including glue,...

  12. Mechanical properties of Hysol EA-9394 structural adhesive

    SciTech Connect

    Guess, T.R.; Reedy, E.D.; Stavig, M.E.

    1995-02-01

    Dextor`s Hysol EA-9394 is a room temperature curable paste adhesive representative of the adhesives used in wind turbine blade joints. A mechanical testing program has been performed to characterize this adhesive. Tension, compression stress relaxation, flexural, butt tensile, and fracture toughness test results are reported.

  13. 16 CFR 1500.133 - Extremely flammable contact adhesives; labeling.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Extremely flammable contact adhesives... REGULATIONS § 1500.133 Extremely flammable contact adhesives; labeling. (a) Extremely flammable contact adhesives, also known as contact bonding cements, when distributed in containers intended or suitable...

  14. 16 CFR 1500.133 - Extremely flammable contact adhesives; labeling.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Extremely flammable contact adhesives... REGULATIONS § 1500.133 Extremely flammable contact adhesives; labeling. (a) Extremely flammable contact adhesives, also known as contact bonding cements, when distributed in containers intended or suitable...

  15. 16 CFR 1500.133 - Extremely flammable contact adhesives; labeling.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Extremely flammable contact adhesives... REGULATIONS § 1500.133 Extremely flammable contact adhesives; labeling. (a) Extremely flammable contact adhesives, also known as contact bonding cements, when distributed in containers intended or suitable...

  16. 16 CFR 1500.133 - Extremely flammable contact adhesives; labeling.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Extremely flammable contact adhesives... REGULATIONS § 1500.133 Extremely flammable contact adhesives; labeling. (a) Extremely flammable contact adhesives, also known as contact bonding cements, when distributed in containers intended or suitable...

  17. 16 CFR 1500.133 - Extremely flammable contact adhesives; labeling.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Extremely flammable contact adhesives... REGULATIONS § 1500.133 Extremely flammable contact adhesives; labeling. (a) Extremely flammable contact adhesives, also known as contact bonding cements, when distributed in containers intended or suitable...

  18. Soy and cottonseed protein blends as wood adhesives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As an environmentally friendlier alternative to adhesives from petroleum feedstock, soy proteins are currently being formulated as wood adhesives. Cottonseed proteins have also been found to provide good adhesive properties. In at least some cases, cottonseed proteins appear to form greater shear ...

  19. Evaluation of surgical anti-adhesion products to reduce postsurgical intra-abdominal adhesion formation in a rat model

    PubMed Central

    Zhang, Hui-Hui; Liao, Ni-Na; Luo, Jing-Wan; Sun, Yu-Long

    2017-01-01

    Background Adhesions frequently occur after abdominal surgery. Many anti-adhesion products have been used in clinic. However, the evidences are short for surgeons to reasonably choose the suitable anti-adhesion produces in clinical practice. This study provided such evidence by comparing the efficiency of five products to prevent abdominal adhesion formation in a rat model. Methods Fifty-six Sprague-Dawley rats were randomly divided into seven groups: sham-operation group, adhesion group, and five product groups (n = 8). The abdomens of rats were opened. The injuries were created on abdominal wall and cecum in the adhesion and product groups. The wounds on abdominal wall and cecum of rats in the adhesion group were not treated before the abdomens were closed. The wounds on abdominal wall and cecum of rats in the product groups were covered with anti-adhesion product: polylactic acid (PLA) film, Seprafilm®, medical polyethylene glycol berberine liquid (PEG), medical sodium hyaluronate gel (HA), or medical chitosan (Chitosan). Fourteen days after surgery, the adhesions were evaluated by incidence, severity, adhesion area on abdominal wall and adhesion breaking strength. Results The application of PLA film and Seprafilm® significantly reduced the incidence, severity, adhesion area and breaking strength of cecum-abdomen adhesion (P<0.05). HA, PEG and Chitosan failed to significantly reduce the cecum-abdomen adhesion (P>0.05). The statistical significances in the incidence and severity of abdomen-adipose adhesion between adhesion group and the product groups were not achieved. However, Seprafilm® was more effective to reduce abdomen-adipose adhesion than PLA film. Furthermore, it was found that the products tested in this study did not effectively reduce cecum-adipose adhesion. The application of PEG could result in abdomen-small intestine adhesion. Conclusion Based on the results of this study, the preference order of anti-adhesion products used to reduce

  20. The effect of bending on the stresses in adhesive joints

    NASA Technical Reports Server (NTRS)

    Yuceoglu, U.; Updike, D. P.

    1975-01-01

    The problem of stress distribution in adhesive joints where two orthotropic plates are bonded through a flexible adhesive layer is analyzed. It is shown that the effect of bending of the adherends on the stresses in the adhesive layer is very significant. The transverse shear deformations of the adherends appear to have little influence on the adhesive layer stresses. The maximum transverse normal stress in the adhesive is shown to be larger than the maximum longitudinal shear stress. The method of solution is applied to several examples of specific joint geometries and material combinations, and is proven to be applicable to other related problems.

  1. Comparative biomorphologic analysis about three dentinal adhesives of last generations.

    PubMed

    Carini, F; Varia, P; Valenza, V

    2001-01-01

    The aim of this work consists in a comparative biomorphological analysis of the properties of infiltration and of adhesion to dental tissues of three among the more used enamel dentinal adhesives of the last generation known with the commercial name of Syntac, Excite and Prompt. The results have given evidence that Syntac has got short adhesion, Excite has got good capacity of infiltration and moderate adhesion, Prompt seems to possess a capacity of infiltration equal to Excite's one, but a better adhesion besides an easier modality of use.

  2. Universal adhesive (glue composition) for electrical porcelain products

    SciTech Connect

    Khristoforov, K.K.; Belen'kaya, E.S.; Omel'chenko, Y.A.; Vinogradova, T.K.

    1986-05-01

    The aim of this work is to develop an adhesive for porcelain insulators that exhibits high physicomechanical properties and increased resistance to the simultaneous action of heat and moisture. One method of solving this problem is to introduce special additives possessing hydrophobic (waterrepelling) properties into the adhesive composition during the process of its preparation. The adhesive based on the ED-20 epoxy resin and TEA hardened with 5 parts of AF-2 additive possesses higher resistance to the action of heat and moisture as compared to the adhesive used at the present time for assembling insulators. The improved and stable physiomechanical properties of the developed adhesive permit its use in any climactic conditions.

  3. Dentin-enamel adhesives in pediatric dentistry: an update.

    PubMed

    García-Godoy, Franklin; Donly, Kevin J

    2015-01-01

    Adhesives and composite technology have made composite resins and polyacid-modified resin-based composites (compomers) very popular as materials to restore primary and permanent anterior and posterior teeth. More conservative preparations can be performed that maintain more tooth structure due to the adhesive properties of the adhesives used with composites and compomers. Meticulous care in the placement of adhesives and, subsequently, resin-based composites and compomers is necessary to produce long-term satisfactory results. The purpose of this paper is to update the current status in regards to dentin-enamel adhesives in primary teeth.

  4. Extracellular matrix-specific focal adhesions in vascular smooth muscle produce mechanically active adhesion sites

    PubMed Central

    Sun, Zhe; Martinez-Lemus, Luis A.; Hill, Michael A.; Meininger, Gerald A.

    2008-01-01

    Integrin-mediated mechanotransduction in vascular smooth muscle cells (VSMCs) plays an important role in the physiological control of tissue blood flow and vascular resistance. To test whether force applied to specific extracellular matrix (ECM)-integrin interactions could induce myogenic-like mechanical activity at focal adhesion sites, we used atomic force microscopy (AFM) to apply controlled forces to specific ECM adhesion sites on arteriolar VSMCs. The tip of AFM probes were fused with a borosilicate bead (2∼5 μm) coated with fibronectin (FN), collagen type I (CNI), laminin (LN), or vitronectin (VN). ECM-coated beads induced clustering of α5- and β3-integrins and actin filaments at sites of bead-cell contact indicative of focal adhesion formation. Step increases of an upward (z-axis) pulling force (800∼1,600 pN) applied to the bead-cell contact site for FN-specific focal adhesions induced a myogenic-like, force-generating response from the VSMC, resulting in a counteracting downward pull by the cell. This micromechanical event was blocked by cytochalasin D but was enhanced by jasplakinolide. Function-blocking antibodies to α5β1- and αvβ3-integrins also blocked the micromechanical cell event in a concentration-dependent manner. Similar pulling experiments with CNI, VN, or LN failed to induce myogenic-like micromechanical events. Collectively, these results demonstrate that mechanical force applied to integrin-FN adhesion sites induces an actin-dependent, myogenic-like, micromechanical event. Focal adhesions formed by different ECM proteins exhibit different mechanical characteristics, and FN appears of particular relevance in its ability to strongly attach to VSMCs and to induce myogenic-like, force-generating reactions from sites of focal adhesion in response to externally applied forces. PMID:18495809

  5. Influence of additional adhesive application on the microtensile bond strength of adhesive systems.

    PubMed

    de Silva, André Luís Faria; Lima, Débora Alves Nunes Leite; de Souza, Grace Mendonça Dias; dos Santos, Carlos Tadeu Dias; Paulillo, Luís Alexandre Maffei Sartini

    2006-01-01

    This study evaluated microtensile bond strength (pTBS) when an additional adhesive layer was applied to the dentin surface. Thirty-five human third molars were flattened to expose the occlusal dentin surface. The teeth were randomly assigned to 7 experimental groups: G1-Single Bond (SB); G2-additional layer of SB; G3--a layer of Scotchbond Multi-purpose (SMP) adhesive applied over SB; G4-Clearfil SE Bond (CE); G5-additional layer of CE; G6-Adper Prompt (AP) and G7-additional layer of AP. For the G2, G3, G5 and G7 groups, the first adhesive layer was light-cured before application of the additional layer. After bonding procedures, 5-mm high composite crowns were incrementally built up. The samples were sectioned to obtain 0.9 x 0.9 beams, which were tested under tension at a crosshead speed of 0.5-mm/minute until failure. The failure mode and adhesive thickness were evaluated under SEM. The pTBS data were analyzed by 1-way ANOVA and post-hoc Ducan's Test (a=0.05). Mean adhesive thickness was analyzed by 1-way ANOVA and post-hoc Tukey's test (a=0.05). The results indicated that G3 presented the highest microTBS and the thickest adhesive layer. G6 and G7 presented the lowest microTBS values. When solvent-free adhesives systems were used, microTBS values were not affected by the thicker layer.

  6. Inhibition of enzymatic degradation of adhesive-dentin interfaces.

    PubMed

    De Munck, J; Van den Steen, P E; Mine, A; Van Landuyt, K L; Poitevin, A; Opdenakker, G; Van Meerbeek, B

    2009-12-01

    Adhesive procedures activate dentin-associated matrix metalloproteinases (MMPs), and so iatrogenically initiate bond degradation. We hypothesized that adding MMP inhibitors to adhesive primers may prevent this endogenous enzymatic degradation, thereby improving bond durability. A non-specific MMP inhibitor (chlorhexidine) and a MMP-2/9-specific inhibitor (SB-3CT) were admixed to the primers of an etch & rinse and a self-etch adhesive, both considered as gold-standard adhesives within their respective categories. For dentin powder exposed to the adhesives under clinical application conditions, gelatin zymography revealed the release of MMP-2 (not of MMP-9) by the etch & rinse adhesive, while no release of enzymes could be detected for the mild self-etch adhesive, most likely because of its limited dentin demineralization effect. The built-in MMP inhibitors appeared effective in reducing bond degradation only for the etch & rinse adhesive, and not for the self-etch adhesive. Water sorption of adhesive interfaces most likely remains the principal mechanism of bond degradation, while endogenous enzymes appear to contribute to bond degradation of only etch & rinse adhesives.

  7. On the mechanical properties of bovine serum albumin (BSA) adhesives.

    PubMed

    Berchane, N S; Andrews, M J; Kerr, S; Slater, N K H; Jebrail, F F

    2008-04-01

    Biological adhesives, natural and synthetic, are of current active interest. These adhesives offer significant advantages over traditional sealant techniques, in particular, they are easier to use, and can play an integral part in the healing mechanism of tissue. Thus, biological adhesives can play a major role in medical applications if they possess adequate mechanical behavior and stability over time. In this work, we report on the method of preparation of bovine serum albumin (BSA) into a biological adhesive. We present quantitative measurements that show the effect of BSA concentration and cross-linker content on the bonding strength of BSA adhesive to wood. A comparison is then made with synthetic poly(glycidyl methacrylate) (PGMA) adhesive, and a commercial cyanoacrylate glue, which was used as a control adhesive. In addition, BSA samples were prepared and characterized for their water content, tensile strength, and elasticity. We show that on dry surface, BSA adhesive exhibits a high bonding strength that is comparable with non-biological commercial cyanoacrylate glues, and synthetic PGMA adhesive. Tensile testing on wet wood showed a slight increase in the bonding strength of BSA adhesive, a considerable decrease in the bonding strength of cyanoacrylate glue, and negligible adhesion of PGMA. Tests performed on BSA samples demonstrate that initial BSA concentration and final water content have a significant effect on the stress-strain behavior of the samples.

  8. Adhesion family of G protein-coupled receptors and cancer.

    PubMed

    Lin, Hsi-Hsien

    2012-01-01

    The adhesion-class G protein-coupled receptors (adhesion-GPCRs) constitute the second largest GPCR sub-family in humans. Adhesion-GPCRs are defined by the chimeric structure of an unusually large extracellular cell-adhesion domain and a GPCR-like seven-pass transmembrane domain. Adhesion-GPCRs are hence expected to display both cellular adhesion and signaling functions in many biological systems. Adhesion-GPCRs are normally expressed in the central nervous, immune, and reproductive systems in a cell type- or tissue-restricted fashion. However, aberrant expression of distinct adhesion-GPCR molecules has been identified in various human cancers with some of the receptors closely associated with cancer development. Tumor-associated adhesion-GPCRs are thought to involve in tumorigenesis by affecting the growth of tumor cells, angiogenesis, tumor cell migration, invasion and metastasis either positively or negatively. Furthermore, some adhesion-GPCRs are considered potential biomarkers for specific types of cancers. In this review article, the expressional characteristics and functional role of cancer-associated adhesion-GPCRs are discussed in depth.

  9. Adhesive capsulitis: a review of current treatment.

    PubMed

    Neviaser, Andrew S; Hannafin, Jo A

    2010-11-01

    Adhesive capsulitis is characterized by a painful, gradual loss of both active and passive glenohumeral motion resulting from progressive fibrosis and ultimate contracture of the glenohumeral joint capsule. Variable nomenclature, inconsistent reporting of disease staging, and a multitude of different treatments have created a confusing and contradictory body of literature about this condition. Our purpose is to review the evidence for both nonsurgical and surgical management of adhesive capsulitis with an emphasis on level I and II studies when available. Significant deficits in the literature include a paucity of randomized controlled trials, failure to report response to treatment in a stage-based fashion, and an incomplete understanding of the disease's natural course. Recognition that the clinical stages reflect a progression in the underlying pathological changes should guide future treatments.

  10. Neutrophil adhesion and activation under flow

    PubMed Central

    Zarbock, Alexander; Ley, Klaus

    2009-01-01

    Neutrophil recruitment into inflamed tissue in response to injury or infection is tightly regulated. Reduced neutrophil recruitment can result in a reduced ability to fight invading microorganisms. During inflammation, neutrophils roll along the endothelial wall of postcapillary venules and integrate inflammatory signals. Neutrophil activation by selectins and chemokines regulates integrin adhesiveness. Binding of activated integrins to their counter-receptors on endothelial cells induces neutrophil arrest and firm adhesion. Adherent neutrophils can be further activated to undergo cytoskeletal rearrangement, crawling, transmigration, superoxide production and respiratory burst. Signaling through G-protein coupled receptors, selectin ligands, Fc receptors and outside-in signaling of integrins are all involved in neutrophil activation, but their interplay in the multistep process of recruitment are only beginning to emerge. This review provides an overview of signaling in rolling and adherent neutrophils. PMID:19037827

  11. Permeability of dentin to adhesive agents.

    PubMed

    Pashley, D H; Ciucchi, B; Sano, H; Horner, J A

    1993-09-01

    The permeability of dentin to adhesive agents is of crucial importance in obtaining good dentinal bonding. In those systems that remove the smear layer, the opportunity exists for resin to infiltrate both tubules and intertubular dentin. Resin penetration into tubules can effectively seal the tubules and can contribute to bond strength if the resin bonds to the tubule wall. Resin infiltration into intertubular dentin can only occur if the mineral phase of dentin is removed by acidic conditioners or chelators. This is more easily accomplished in fractured dentin than in smear layer-covered dentin because of the residual collagen debris that remains on the surface following acid etching of smear layers. The channels for resin infiltration are the perifibrillar spaces created around the collagen fibers of dentin following removal of apatite mineral by acids. The diffusion of adhesive resins through these narrow, tortuous, long channels in 1 to 2 minutes offers a number of challenges that require further research.

  12. Adhesive joint and composites modeling in SIERRA.

    SciTech Connect

    Ohashi, Yuki; Brown, Arthur A.; Hammerand, Daniel Carl; Adolf, Douglas Brian; Chambers, Robert S.; Foulk, James W., III

    2005-11-01

    Polymers and fiber-reinforced polymer matrix composites play an important role in many Defense Program applications. Recently an advanced nonlinear viscoelastic model for polymers has been developed and incorporated into ADAGIO, Sandia's SIERRA-based quasi-static analysis code. Standard linear elastic shell and continuum models for fiber-reinforced polymer-matrix composites have also been added to ADAGIO. This report details the use of these models for advanced adhesive joint and composites simulations carried out as part of an Advanced Simulation and Computing Advanced Deployment (ASC AD) project. More specifically, the thermo-mechanical response of an adhesive joint when loaded during repeated thermal cycling is simulated, the response of some composite rings under internal pressurization is calculated, and the performance of a composite container subjected to internal pressurization, thermal loading, and distributed mechanical loading is determined. Finally, general comparisons between the continuum and shell element approaches for modeling composites using ADAGIO are given.

  13. Microscopic lysis of lumbar adhesive arachnoiditis.

    PubMed

    Johnston, J D; Matheny, J B

    1978-03-01

    The results of a long-term study of 28 patients operated on for adhesive lumbar arachnoiditis are presented. The technique involved was microscopic lysis of adhesions. The first case of surgery was performed in 1966 and the last, in 1970, with followup through 1976. Numerous observations are made regarding the clinical picture and the appearance of arachnoiditis at the time of surgery. Some conclusions are drawn regarding the causes of this condition with some emphasis on the role of Pantopaque, multiple surgeries, and other trauma. The conclusion is that surgical attack on arachnoiditis is a straightforward surgical exercise that, when carried out with appropriate caution, produces no further neurologic deficits and some short-term improvement. However, the authors feel that this procedure should not be performed at the present time because there does not appear to be a method for preventing the reaccumulation of the scar tissue and subsequent recurrence of the symptoms.

  14. Surface Modifications in Adhesion and Wetting

    NASA Astrophysics Data System (ADS)

    Longley, Jonathan

    Advances in surface modification are changing the world. Changing surface properties of bulk materials with nanometer scale coatings enables inventions ranging from the familiar non-stick frying pan to advanced composite aircraft. Nanometer or monolayer coatings used to modify a surface affect the macro-scale properties of a system; for example, composite adhesive joints between the fuselage and internal frame of Boeing's 787 Dreamliner play a vital role in the structural stability of the aircraft. This dissertation focuses on a collection of surface modification techniques that are used in the areas of adhesion and wetting. Adhesive joints are rapidly replacing the familiar bolt and rivet assemblies used by the aerospace and automotive industries. This transition is fueled by the incorporation of composite materials into aircraft and high performance road vehicles. Adhesive joints have several advantages over the traditional rivet, including, significant weight reduction and efficient stress transfer between bonded materials. As fuel costs continue to rise, the weight reduction is accelerating this transition. Traditional surface pretreatments designed to improve the adhesion of polymeric materials to metallic surfaces are extremely toxic. Replacement adhesive technologies must be compatible with the environment without sacrificing adhesive performance. Silane-coupling agents have emerged as ideal surface modifications for improving composite joint strength. As these coatings are generally applied as very thin layers (<50 nm), it is challenging to characterize their material properties for correlation to adhesive performance. We circumvent this problem by estimating the elastic modulus of the silane-based coatings using the buckling instability formed between two materials of a large elastic mismatch. The elastic modulus is found to effectively predict the joint strength of an epoxy/aluminum joint that has been reinforced with silane coupling agents. This buckling

  15. On coating adhesion during impulse plasma deposition

    NASA Astrophysics Data System (ADS)

    Nowakowska-Langier, Katarzyna; Zdunek, Krzysztof; Chodun, Rafal; Okrasa, Sebastian; Kwiatkowski, Roch; Malinowski, Karol; Składnik-Sadowska, Elzbieta; Sadowski, Marek J.

    2014-05-01

    The impulse plasma deposition (IPD) technique is the only method of plasma surface engineering (among plasma-based technologies) that allows a synthesis of layers upon a cold unheated substrate and which ensures a good adhesion. This paper presents a study of plasma impacts upon a copper substrate surface during the IPD process. The substrate was exposed to pulsed N2/Al plasma streams during the synthesis of AlN layers. For plasma-material interaction diagnostics, the optical emission spectroscopy method was used. Our results show that interactions of plasma lead to sputtering of the substrate material. It seems that the obtained adhesion of the layers is the result of a complex surface mechanism combined with the effects of pulsed plasma energy impacts upon the unheated substrate. An example of such a result is the value of the critical load for the Al2O3 layer, which was measured by the scratch-test method to be above 40 N.

  16. Adhesion determinants of the Streptococcus species

    PubMed Central

    Moschioni, Monica; Pansegrau, Werner; Barocchi, Michèle A.

    2010-01-01

    Summary Streptococci are clinically important Gram‐positive bacteria that are capable to cause a wide variety of diseases in humans and animals. Phylogenetic analyses based on 16S rRNA sequences of the streptococcal species reveal a clustering pattern, reflecting, with a few exceptions, their pathogenic potential and ecological preferences. Microbial adhesion to host tissues is the initial critical event in the pathogenesis of most infections. Streptococci use multiple adhesins to attach to the epithelium, and their expression is regulated in response to environmental and growth conditions. Bacterial adhesins recognize and bind cell surface molecules and extracellular matrix components through specific domains that for certain adhesin families have been well defined and found conserved across the streptococcal species. In this review, we present the different streptococcal adhesin families categorized on the basis of their adhesive properties and structural characteristics, and, when available, we focus the attention on conserved functional domains. PMID:21255337

  17. Adhesion and friction of thin metal films

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1976-01-01

    Sliding friction experiments were conducted in vacuum with thin films of titanium, chromium, iron, and platinum sputter deposited on quartz or mica substrates. A single crystal hemispherically tipped gold slider was used in contact with the films at loads of 1.0 to 30.0 and at a sliding velocity of 0.7 mm/min at 23 C. Test results indicate that the friction coefficient is dependent on the adhesion of two interfaces, that between the film and its substrate and the slider and the film. There exists a relationship between the percent d bond character of metals in bulk and in thin film form and the friction coefficient. Oxygen can increase adhesive bonding of a metal film (platinum) to a substrate.

  18. Verification of surface preparation for adhesive bonding

    NASA Technical Reports Server (NTRS)

    Myers, Rodney S.

    1995-01-01

    A survey of solid rocket booster (SRB) production operations identified potential contaminants which might adversely affect bonding operations. Lap shear tests quantified these contaminants' effects on adhesive strength. The most potent contaminants were selected for additional studies on SRB thermal protection system (TPS) bonding processes. Test panels were prepared with predetermined levels of contamination, visually inspected using white and black light, then bonded with three different TPS materials over the unremoved contamination. Bond test data showed that white and black light inspections are adequate inspection methods for TPS bonding operations. Extreme levels of contamination (higher than expected on flight hardware) had an insignificant effect on TPS bond strengths because of the apparent insensitivity of the adhesive system to contamination effects, and the comparatively weak cohesive strength of the TPS materials.

  19. Light-Curing Adhesive Repair Tapes

    NASA Technical Reports Server (NTRS)

    Allred, Ronald; Haight, Andrea Hoyt

    2009-01-01

    Adhesive tapes, the adhesive resins of which can be cured (and thereby rigidized) by exposure to ultraviolet and/or visible light, are being developed as repair patch materials. The tapes, including their resin components, consist entirely of solid, low-outgassing, nonhazardous or minimally hazardous materials. They can be used in air or in vacuum and can be cured rapidly, even at temperatures as low as -20 C. Although these tapes were originally intended for use in repairing structures in outer space, they can also be used on Earth for quickly repairing a wide variety of structures. They can be expected to be especially useful in situations in which it is necessary to rigidize tapes after wrapping them around or pressing them onto the parts to be repaired.

  20. Advanced adhesion and friction measurement system

    NASA Astrophysics Data System (ADS)

    Li, Meng; Huang, Wei; Wang, Xiaolei

    2017-03-01

    An advanced micro-force tester for investigating the micromechanical behavior of various patterned surfaces in dry and wet conditions is presented in this paper. The parallel slice-beam configuration of the tester not only eliminates the large load-dependent slope and tangential displacement at the free end that is found in a single beam system, but also performs a trans-scale deflection with high sensitivity and linearity for force sensing. Meanwhile, the simple structure is characterized by low cost, high efficiency, and ease of fabrication. An integrated nano- and micro-stage comprise the mobile table to produce a large stroke with high resolution, which is specifically required in wet adhesion testing because of the formation of a long liquid bridge. Preliminary experiments of adhesion and friction conducted using PDMS pillars with a plano-convex lens validated the feasibility of this setup.

  1. Inorganic Adhesives for Robust Superwetting Surfaces.

    PubMed

    Liu, Mingming; Li, Jing; Hou, Yuanyuan; Guo, Zhiguang

    2017-01-24

    Superwetting surfaces require micro-/nanohierarchical structures but are mechanically weak. Moreover, such surfaces are easily polluted by amphiphiles. In this work, inorganic adhesives are presented as a building block for construction of superwetting surfaces and to promote robustness. Nanomaterials can be selected as fillers to endow the functions. We adopted a simple procedure to fabricate underwater superoleophobic surfaces by spraying a titanium dioxide suspension combined with aluminum phosphate binder on stainless steel meshes. The surfaces maintained their excellent performance in regard to oil repellency under water, oil/water separation, and self-cleaning properties after even 100 abrasion cycles with sandpaper. Robust superwetting surfaces favored by inorganic adhesives can be extended to other nanoparticles and substrates, which are potentially advantageous in practical applications.

  2. Transfer of adhesive tape between calender rolls

    NASA Astrophysics Data System (ADS)

    Johnson, K. L.; Kauzlarich, J. J.

    2004-03-01

    In the calendering process a tape or sheet of deformable material passes through the nip between hard cylindrical rollers. Usually the rolls are driven at the same peripheral speed, but small differences in speed, often referred to as 'creep', can occur if one of the rolls is externally driven and the other is driven by the friction in the contact. In these circumstances it has been observed that a tape that enters the nip adhering to the driven (slower) surface may transfer at exit to the driving (faster) surface but not the other way round. The mechanics of this transfer process is examined theoretically and experimentally in this paper for the case of double sided adhesive tape. It is argued that on emerging from the nip the tape will separate from the surface at which the shear strain in the adhesive is greater and that for transfer to occur the contact load must be sufficient to cause plastic extension of the tape.

  3. The effects of leaf roughness, surface free energy and work of adhesion on leaf water drop adhesion.

    PubMed

    Wang, Huixia; Shi, Hui; Li, Yangyang; Wang, Yanhui

    2014-01-01

    The adhesion of water droplets to leaves is important in controlling rainfall interception, and affects a variety of hydrological processes. Leaf water drop adhesion (hereinafter, adhesion) depends not only on droplet formulation and parameters but also on the physical (leaf roughness) and physico-chemical (surface free energy, its components, and work-of-adhesion) properties of the leaf surface. We selected 60 plant species from Shaanxi Province, NW China, as experimental materials with the goal of gaining insight into leaf physical and physico-chemical properties in relation to the adhesion of water droplets on leaves. Adhesion covered a wide range of area, from 4.09 to 88.87 g/m(2) on adaxial surfaces and 0.72 to 93.35 g/m(2) on abaxial surfaces. Distinct patterns of adhesion were observed among species, between adaxial and abaxial surfaces, and between leaves with wax films and wax crystals. Adhesion decreased as leaf roughness increased (r =  -0.615, p = 0.000), but there were some outliers, such as Salix psammophila and Populus simonii with low roughness and low adhesion, and the abaxial surface of Hyoscyamus pusillus and the adaxial surface of Vitex negundo with high roughness and high adhesion. Meanwhile, adhesion was positively correlated with surface free energy (r = 0.535, p = 0.000), its dispersive component (r = 0.526, p = 0.000), and work of adhesion for water (r = 0.698, p = 0.000). However, a significant power correlation was observed between adhesion and the polar component of surface free energy (p = 0.000). These results indicated that leaf roughness, surface free energy, its components, and work-of-adhesion for water played important roles in hydrological characteristics, especially work-of-adhesion for water.

  4. Understanding Surface Adhesion in Nature: A Peeling Model

    PubMed Central

    Gu, Zhen; Li, Siheng; Zhang, Feilong

    2016-01-01

    Nature often exhibits various interesting and unique adhesive surfaces. The attempt to understand the natural adhesion phenomena can continuously guide the design of artificial adhesive surfaces by proposing simplified models of surface adhesion. Among those models, a peeling model can often effectively reflect the adhesive property between two surfaces during their attachment and detachment processes. In the context, this review summarizes the recent advances about the peeling model in understanding unique adhesive properties on natural and artificial surfaces. It mainly includes four parts: a brief introduction to natural surface adhesion, the theoretical basis and progress of the peeling model, application of the peeling model, and finally, conclusions. It is believed that this review is helpful to various fields, such as surface engineering, biomedicine, microelectronics, and so on. PMID:27812476

  5. Biological adhesive based on carboxymethyl chitin derivatives and chitin nanofibers.

    PubMed

    Azuma, Kazuo; Nishihara, Masahiro; Shimizu, Haruki; Itoh, Yoshiki; Takashima, Osamu; Osaki, Tomohiro; Itoh, Norihiko; Imagawa, Tomohiro; Murahata, Yusuke; Tsuka, Takeshi; Izawa, Hironori; Ifuku, Shinsuke; Minami, Saburo; Saimoto, Hiroyuki; Okamoto, Yoshiharu; Morimoto, Minoru

    2015-02-01

    Novel biological adhesives made from chitin derivatives were prepared and evaluated for their adhesive properties and biocompatibility. Chitin derivatives with acrylic groups, such as 2-hydroxy-3-methacryloyloxypropylated carboxymethyl chitin (HMA-CM-chitin), were synthesized and cured by the addition of an aqueous hydrogen peroxide solution as a radical initiator. The adhesive strength of HMA-CM-chitin increased when it was blended with chitin nanofibers (CNFs) or surface-deacetylated chitin nanofibers (S-DACNFs). HMA-CM-chitin/CNFs or HMA-CM-chitin/S-DACNFs have almost equal adhesive strength compared to that of a commercial cyanoacrylate adhesive. Moreover, quick adhesion and induction of inflammatory cells migration were observed in HMA-CM-chitin/CNF and HMA-CM-chitin/S-DACNF. These findings indicate that the composites prepared in this study are promising materials as new biological adhesives.

  6. Biomimetic adhesive materials containing cyanoacryl group for medical application.

    PubMed

    Jo, Sueng Hwan; Sohn, Jeong Sun

    2014-10-17

    For underwater adhesives with biocompatible and more flexible bonds using biomimetic adhesive groups, DOPA-like adhesive molecules were modified with cyanoacrylates to obtain different repeating units and chain length copolymers. The goal of this work is to copy the mechanisms of underwater bonding to create synthetic water-borne underwater medical adhesives through blending of the modified DOPA and a triblock copolymer (PEO-PPO-PEO) for practical application to repair wet living tissues and bones, and in turn, to use the synthetic adhesives to test mechanistic hypotheses about the natural adhesive. The highest values in stress and modulus of the biomimetic adhesives prepared in wet state were 165 kPa and 33 MPa, respectively.

  7. High-performance mussel-inspired adhesives of reduced complexity

    PubMed Central

    Ahn, B. Kollbe; Das, Saurabh; Linstadt, Roscoe; Kaufman, Yair; Martinez-Rodriguez, Nadine R.; Mirshafian, Razieh; Kesselman, Ellina; Talmon, Yeshayahu; Lipshutz, Bruce H.; Israelachvili, Jacob N.; Waite, J. Herbert

    2015-01-01

    Despite the recent progress in and demand for wet adhesives, practical underwater adhesion remains limited or non-existent for diverse applications. Translation of mussel-inspired wet adhesion typically entails catechol functionalization of polymers and/or polyelectrolytes, and solution processing of many complex components and steps that require optimization and stabilization. Here we reduced the complexity of a wet adhesive primer to synthetic low-molecular-weight catecholic zwitterionic surfactants that show very strong adhesion (∼50 mJ m−2) and retain the ability to coacervate. This catecholic zwitterion adheres to diverse surfaces and self-assembles into a molecularly smooth, thin (<4 nm) and strong glue layer. The catecholic zwitterion holds particular promise as an adhesive for nanofabrication. This study significantly simplifies bio-inspired themes for wet adhesion by combining catechol with hydrophobic and electrostatic functional groups in a small molecule. PMID:26478273

  8. High-performance mussel-inspired adhesives of reduced complexity.

    PubMed

    Ahn, B Kollbe; Das, Saurabh; Linstadt, Roscoe; Kaufman, Yair; Martinez-Rodriguez, Nadine R; Mirshafian, Razieh; Kesselman, Ellina; Talmon, Yeshayahu; Lipshutz, Bruce H; Israelachvili, Jacob N; Waite, J Herbert

    2015-10-19

    Despite the recent progress in and demand for wet adhesives, practical underwater adhesion remains limited or non-existent for diverse applications. Translation of mussel-inspired wet adhesion typically entails catechol functionalization of polymers and/or polyelectrolytes, and solution processing of many complex components and steps that require optimization and stabilization. Here we reduced the complexity of a wet adhesive primer to synthetic low-molecular-weight catecholic zwitterionic surfactants that show very strong adhesion (∼50 mJ m(-2)) and retain the ability to coacervate. This catecholic zwitterion adheres to diverse surfaces and self-assembles into a molecularly smooth, thin (<4 nm) and strong glue layer. The catecholic zwitterion holds particular promise as an adhesive for nanofabrication. This study significantly simplifies bio-inspired themes for wet adhesion by combining catechol with hydrophobic and electrostatic functional groups in a small molecule.

  9. Isolation and biochemical characterization of underwater adhesives from diatoms.

    PubMed

    Poulsen, Nicole; Kröger, Nils; Harrington, Matthew J; Brunner, Eike; Paasch, Silvia; Buhmann, Matthias T

    2014-01-01

    Many aquatic organisms are able to colonize surfaces through the secretion of underwater adhesives. Diatoms are unicellular algae that have the capability to colonize any natural and man-made submerged surfaces. There is great technological interest in both mimicking and preventing diatom adhesion, yet the biomolecules responsible have so far remained unidentified. A new method for the isolation of diatom adhesive material is described and its amino acid and carbohydrate composition determined. The adhesive materials from two model diatoms show differences in their amino acid and carbohydrate compositions, but also share characteristic features including a high content of uronic acids, the predominance of hydrophilic amino acid residues, and the presence of 3,4-dihydroxyproline, an extremely rare amino acid. Proteins containing dihydroxyphenylalanine, which mediate underwater adhesion of mussels, are absent. The data on the composition of diatom adhesives are consistent with an adhesion mechanism based on complex coacervation of polyelectrolyte-like biomolecules.

  10. Universal aspects of brittle fracture, adhesion, and atomic force microscopy

    NASA Technical Reports Server (NTRS)

    Banerjea, Amitava; Ferrante, John; Smith, John R.

    1989-01-01

    This universal relation between binding energy and interatomic separation was originally discovered for adhesion at bimetallic interfaces involving the simple metals Al, Zn, Mg, and Na. It is shown here that the same universal relation extends to adhesion at transition-metal interfaces. Adhesive energies have been computed for the low-index interfaces of Al, Ni, Cu, Ag, Fe, and W, using the equivalent-crystal theory (ECT) and keeping the atoms in each semiinfinite slab fixed rigidly in their equilibrium positions. These adhesive energy curves can be scaled onto each other and onto the universal adhesion curve. The effect of tip shape on the adhesive forces in the atomic-force microscope (AFM) is studied by computing energies and forces using the ECT. While the details of the energy-distance and force-distance curves are sensitive to tip shape, all of these curves can be scaled onto the universal adhesion curve.

  11. Prevention of peritoneal adhesions: A promising role for gene therapy

    PubMed Central

    Atta, Hussein M

    2011-01-01

    Adhesions are the most frequent complication of abdominopelvic surgery, yet the extent of the problem, and its serious consequences, has not been adequately recognized. Adhesions evolved as a life-saving mechanism to limit the spread of intraperitoneal inflammatory conditions. Three different pathophysiological mechanisms can independently trigger adhesion formation. Mesothelial cell injury and loss during operations, tissue hypoxia and inflammation each promotes adhesion formation separately, and potentiate the effect of each other. Studies have repeatedly demonstrated that interruption of a single pathway does not completely prevent adhesion formation. This review summarizes the pathogenesis of adhesion formation and the results of single gene therapy interventions. It explores the promising role of combinatorial gene therapy and vector modifications for the prevention of adhesion formation in order to stimulate new ideas and encourage rapid advancements in this field. PMID:22171139

  12. Microgel adhesives for wet cellulose: measurements and modeling.

    PubMed

    Wen, Quan; Pelton, Robert

    2012-03-27

    Nanostructured adhesive layers were prepared by adsorbing and/or grafting polyvinylamine (PVAm) onto carboxylated poly(N-isopropylacrylamide) (PNIPAM) microgels that were then assembled between layers of wet oxidized cellulose. The wet delamination force was measured as functions of PVAm content, PVAm molecular weight, coverage (mass adhesive/joint area), and the distribution of carboxyl groups in the PNIPAM microgels. The use of microgels is attractive because simple physical adsorption onto the cellulose surfaces before lamination gives much higher adhesive content and strength compared to the corresponding adsorbed linear PVAm. Wet adhesion increased with PVAm content in the microgels and the quantity of microgels in the joint whereas adhesion was independent of PVAm molecular weight. Physical adsorption of the PVAm onto/into the microgels gave the same adhesion as covalently coupled PVAm. Finally, the roles of microgel diameter, elasticity, and coverage were simulated by a simple peel adhesion model in which the microgels were treated as ideal springs.

  13. Tongue adhesion in the horned frog Ceratophrys sp.

    NASA Astrophysics Data System (ADS)

    Kleinteich, Thomas; Gorb, Stanislav N.

    2014-06-01

    Frogs are well-known to capture elusive prey with their protrusible and adhesive tongues. However, the adhesive performance of frog tongues and the mechanism of the contact formation with the prey item remain unknown. Here we measured for the first time adhesive forces and tongue contact areas in living individuals of a horned frog (Ceratophrys sp.) against glass. We found that Ceratophrys sp. generates adhesive forces well beyond its own body weight. Surprisingly, we found that the tongues adhered stronger in feeding trials in which the coverage of the tongue contact area with mucus was relatively low. Thus, besides the presence of mucus, other features of the frog tongue (surface profile, material properties) are important to generate sufficient adhesive forces. Overall, the experimental data shows that frog tongues can be best compared to pressure sensitive adhesives (PSAs) that are of common technical use as adhesive tapes or labels.

  14. Tongue adhesion in the horned frog Ceratophrys sp.

    PubMed Central

    Kleinteich, Thomas; Gorb, Stanislav N.

    2014-01-01

    Frogs are well-known to capture elusive prey with their protrusible and adhesive tongues. However, the adhesive performance of frog tongues and the mechanism of the contact formation with the prey item remain unknown. Here we measured for the first time adhesive forces and tongue contact areas in living individuals of a horned frog (Ceratophrys sp.) against glass. We found that Ceratophrys sp. generates adhesive forces well beyond its own body weight. Surprisingly, we found that the tongues adhered stronger in feeding trials in which the coverage of the tongue contact area with mucus was relatively low. Thus, besides the presence of mucus, other features of the frog tongue (surface profile, material properties) are important to generate sufficient adhesive forces. Overall, the experimental data shows that frog tongues can be best compared to pressure sensitive adhesives (PSAs) that are of common technical use as adhesive tapes or labels. PMID:24921415

  15. High-performance mussel-inspired adhesives of reduced complexity

    NASA Astrophysics Data System (ADS)

    Ahn, B. Kollbe; Das, Saurabh; Linstadt, Roscoe; Kaufman, Yair; Martinez-Rodriguez, Nadine R.; Mirshafian, Razieh; Kesselman, Ellina; Talmon, Yeshayahu; Lipshutz, Bruce H.; Israelachvili, Jacob N.; Waite, J. Herbert

    2015-10-01

    Despite the recent progress in and demand for wet adhesives, practical underwater adhesion remains limited or non-existent for diverse applications. Translation of mussel-inspired wet adhesion typically entails catechol functionalization of polymers and/or polyelectrolytes, and solution processing of many complex components and steps that require optimization and stabilization. Here we reduced the complexity of a wet adhesive primer to synthetic low-molecular-weight catecholic zwitterionic surfactants that show very strong adhesion (~50 mJ m-2) and retain the ability to coacervate. This catecholic zwitterion adheres to diverse surfaces and self-assembles into a molecularly smooth, thin (<4 nm) and strong glue layer. The catecholic zwitterion holds particular promise as an adhesive for nanofabrication. This study significantly simplifies bio-inspired themes for wet adhesion by combining catechol with hydrophobic and electrostatic functional groups in a small molecule.

  16. Motility and Adhesiveness in Human Neutrophils

    PubMed Central

    Smith, C. Wayne; Hollers, James C.; Patrick, Richard A.; Hassett, Clare

    1979-01-01

    Human peripheral blood neutrophils (PMN) obtained from healthy adults were examined in vitro with techniques adapted to assess the effects of chemotactic factors (CF) on cellular configuration and adhesiveness. The results were compared with those that use certain conventional techniques for assessing chemotaxis and chemokinesis. Exposure of PMN to N-formyl-l-methionyl-l-phenylalanine (f-Met-Phe), zymosan-activated serum, bacterial chemotactic factor, or a low molecular weight chemotactic factor from activated serum (C5a) in the absence of a gradient resulted in a change in cellular shape from a spherical to a polarized configuration in a high percentage of cells. This occurred rapidly in suspension, under conditions designed to exclude a role for cell adhesiveness, and was reversible upon removal of the CF. Restimulation of cells with the CF resulted in reappearance of the polarized configuration to the same extent as on initial stimulation with one exception: f-Met-Phe pretreated cells failed to respond to f-Met-Phe, though they responded fully to the other CF. Each CF caused a significant increase in PMN attachment to protein-coated glass. This enhanced adhesiveness was not reversible upon removal of the CF when the cells were treated under conditions shown to produce chemotactic deactivation. Cells treated under these conditions also exhibited significantly reduced motility on glass and in micropore filters in the absence of a gradient of CF. Bacterial chemotactic factor, even at high concentrations, failed to produce deactivation and did not cause a sustained enhancement of adhesiveness. Images PMID:372238

  17. Adhesive Electroless Metallization of Fluoropolymeric Substrates

    NASA Astrophysics Data System (ADS)

    Vargo, Terrence G.; Gardella, Joseph A., Jr.; Calvert, Jeffrey M.; Chen, Mu-San

    1993-12-01

    A process for producing patterned metal deposits on fluoropolymeric substrates is described. A metal ion-chelating organosilane is chemisorbed by self-assembly onto a fluoropolymer surface after radio-frequency glow discharge plasma surface hydroxylation. Positional modulation of the surface hydrophobicity is illustrated by wetting. The silane covalently binds an aqueous palladium catalyst and subsequent electroless deposition yields homogeneous or patterned metal deposits that exhibit excellent adhesion to the fluoropolymer.

  18. Characterization and Cure Monitoring of Structural Adhesives

    DTIC Science & Technology

    1989-02-01

    OX tiLE (OP? MTL TR 89-15 AD CHARACTERIZATION AND CURE MONITORING OF STRUCTURAL ADHESIVES CD WALTER X. ZUKAS, HOWARD H. WONG, DAVID A. DUNN, and...REPORT NUMB3ER 7. AUTHOR(s) 8. CONTRACT OR GRANT NUMBERs) Walter X. Zukas, Howard H. Wong, David A. Dunn, and Stanley E. Wentworth I. PERFORING...Technology, Gaithersburg, MD 20899 1 ATTN: B. Fanconi, Polymer Standards Division 1 D. Hunston, Polymer Standards Division 1 Dr. Stanley M. Barkin , Staff

  19. Nonlinear viscoelastic characterization of structural adhesives

    NASA Technical Reports Server (NTRS)

    Rochefort, M. A.; Brinson, H. F.

    1983-01-01

    Measurements of the nonliner viscoelastic behavior of two adhesives, FM-73 and FM-300, are presented and discussed. Analytical methods to quantify the measurements are given and fitted into a framework of an accelerated testing and analysis procedure. The single integral model used is shown to function well and is analogous to a time-temperature stress-superposition procedure (TTSSP). Advantages and disadvantages of the creep power law method used in this study are given.

  20. Enhanced adhesion by high energy bombardment

    NASA Technical Reports Server (NTRS)

    Griffith, Joseph E. (Inventor); Qiu, Yuanxun (Inventor); Tombrello, Thomas A. (Inventor)

    1984-01-01

    Films (12) of gold, copper, silicon nitride, or other materials are firmly bonded to insulator substrates (12) such as silica, a ferrite, or Teflon (polytetrafluorethylene) by irradiating the interface with high energy ions. Apparently, track forming processes in the electronic stopping region cause intermixing in a thin surface layer resulting in improved adhesion without excessive doping. Thick layers can be bonded by depositing or doping the interfacial surfaces with fissionable elements or alpha emitters.

  1. Aluminum ion-containing polyimide adhesives

    NASA Technical Reports Server (NTRS)

    St.clair, A. K.; Taylor, L. T.; St.clair, T. L. (Inventor)

    1981-01-01

    A meta-oriented aromatic diamine is reacted with an aromatic dianhydride and an aluminum compound in the presence of a water or lower alkanol miscible ether solvent to produce an intermediate polyamic acid. The polyamic acid is then converted to the thermally stable, metal ion-filled polyimide by heating in the temperature range of 300 C to produce a flexible, high temperature adhesive.

  2. Use of cyanoacrylate adhesives in general surgery.

    PubMed

    García Cerdá, David; Ballester, Antonio Martín; Aliena-Valero, Alicia; Carabén-Redaño, Anna; Lloris, José M

    2015-08-01

    This paper presents a review of the use of cyanoacrylate adhesives (CA) in general surgery and digestive surgery, studies the mechanisms of action and interactions of CAs in adherent tissues, and compiles data on the latest experimental and clinical applications. More than seven million traumatic injuries are estimated to occur every year, and between 26 and 90 million surgical procedures using different techniques are performed to close the resulting wounds. Traditional methods not only are both useful and effective, but also have some drawbacks. This review covers a considerable number of surgical procedures for which CAs had satisfactory results. The adhesive facilitated the healing of very diverse tissues, such as solid organs, vascular tissue or the abdominal wall. In other cases, no significant differences were found when CA was compared to traditional methods, with the adhesive standing out as a simple and reliable solution. The number of procedures in which CA was detrimental was very low. This review also collects and describes these. In conclusion, the surgical fields and procedures in which CA was successfully used are highly diverse. This review will allow physicians to determine which techniques were first used experimentally, but finally settled in clinical practice as feasible alternatives to standard treatments.

  3. Adhesion of Pseudomonas fluorescens onto nanophase materials

    NASA Astrophysics Data System (ADS)

    Webster, Thomas J.; Tong, Zonghua; Liu, Jin; Banks, M. Katherine

    2005-07-01

    Nanobiotechnology is a growing area of research, primarily due to the potentially numerous applications of new synthetic nanomaterials in engineering/science. Although various definitions have been given for the word 'nanomaterials' by many different experts, the commonly accepted one refers to nanomaterials as those materials which possess grains, particles, fibres, or other constituent components that have one dimension specifically less than 100 nm. In biological applications, most of the research to date has focused on the interactions between mammalian cells and synthetic nanophase surfaces for the creation of better tissue engineering materials. Although mammalian cells have shown a definite positive response to nanophase materials, information on bacterial interactions with nanophase materials remains elusive. For this reason, this study was designed to assess the adhesion of Pseudomonas fluorescens on nanophase compared to conventional grain size alumina substrates. Results provide the first evidence of increased adhesion of Pseudomonas fluorescens on alumina with nanometre compared to conventional grain sizes. To understand more about the process, polymer (specifically, poly-lactic-co-glycolic acid or PLGA) casts were made of the conventional and nanostructured alumina surfaces. Results showed similar increased Pseudomonas fluorescens capture on PLGA casts of nanostructured compared to conventional alumina as on the alumina itself. For these reasons, a key material property shown to enhance bacterial adhesion was elucidated in this study for both polymers and ceramics: nanostructured surface features.

  4. Adhesive sealing of the pulp chamber.

    PubMed

    Belli, S; Zhang, Y; Pereira, P N; Pashley, D H

    2001-08-01

    The purpose of this in vitro study was to evaluate quantitatively the ability of four different filling materials to seal the orifices of root canals as a secondary seal after root canal therapy. Forty extracted human molar teeth were used. The top of pulp chambers and distal halves of the roots were removed using an Isomet saw. The canal orifices were temporarily sealed with a gutta-percha master cone without sealer. The pulp chambers were then treated with a self-etching primer adhesive system (Clearfil SE Bond), a wet bonding system (One-Step), a 4-methacryloyloxyethyl trimellitate anhydride adhesive system (C&B Metabond), or a reinforced zinc oxide-eugenol (IRM). The specimens were randomly divided into four groups of 10 each. A fluid filtration method was used for quantitative evaluation of leakage. Measurements of fluid movement were made at 2-min intervals for 8 min. The quality of the seal of each specimen was measured by fluid filtration immediately and after 1 day, 1 wk, and 1 month. Even after 1 month the resins showed an excellent seal. Zinc oxide-eugenol had significantly more leakage when compared with the resin systems (p < 0.05). Adhesive resins should be considered as a secondary seal to prevent intraorifice microleakage.

  5. The thoracic anterior spinal cord adhesion syndrome

    PubMed Central

    Taylor, T R; Dineen, R; White, B; Jaspan, T

    2012-01-01

    Objectives This study included a series of middle-aged male and female patients who presented with chronic anterior hemicord dysfunction progressing to paraplegia. Imaging of anterior thoracic cord displacement by either a dural adhesion or a dural defect with associated cord herniation is presented. Methods This is a retrospective review of cases referred to a tertiary neuroscience centre over a 19-year period. Imaging series were classified by two experienced neuroradiologists against several criteria and correlated with clinical examination and/or findings at surgery. Results 16 cases were available for full review. Nine were considered to represent adhesions (four confirmed surgically) and four to represent true herniation (three confirmed surgically). In the three remaining cases the diagnosis was radiologically uncertain. Conclusion The authors propose “thoracic anterior spinal cord adhesion syndrome” as a novel term to describe this patient cohort and suggest appropriate clinicoradiological features for diagnosis. Several possible aetiologies are also suggested, with disc rupture and inflammation followed by disc resorption and dural pocket formation being a possible mechanism predisposing to herniation at the extreme end of a clinicopathological spectrum. PMID:22665931

  6. Multi-scale models for cell adhesion

    NASA Astrophysics Data System (ADS)

    Wu, Yinghao; Chen, Jiawen; Xie, Zhong-Ru

    2014-03-01

    The interactions of membrane receptors during cell adhesion play pivotal roles in tissue morphogenesis during development. Our lab focuses on developing multi-scale models to decompose the mechanical and chemical complexity in cell adhesion. Recent experimental evidences show that clustering is a generic process for cell adhesive receptors. However, the physical basis of such receptor clustering is not understood. We introduced the effect of molecular flexibility to evaluate the dynamics of receptors. By delivering new theory to quantify the changes of binding free energy in different cellular environments, we revealed that restriction of molecular flexibility upon binding of membrane receptors from apposing cell surfaces (trans) causes large entropy loss, which dramatically increases their lateral interactions (cis). This provides a new molecular mechanism to initialize receptor clustering on the cell-cell interface. By using the subcellular simulations, we further found that clustering is a cooperative process requiring both trans and cis interactions. The detailed binding constants during these processes are calculated and compared with experimental data from our collaborator's lab.

  7. Wetting and phase separation in soft adhesion

    PubMed Central

    Jensen, Katharine E.; Sarfati, Raphael; Style, Robert W.; Boltyanskiy, Rostislav; Chakrabarti, Aditi; Chaudhury, Manoj K.; Dufresne, Eric R.

    2015-01-01

    In the classic theory of solid adhesion, surface energy drives deformation to increase contact area whereas bulk elasticity opposes it. Recently, solid surface stress has been shown also to play an important role in opposing deformation of soft materials. This suggests that the contact line in soft adhesion should mimic that of a liquid droplet, with a contact angle determined by surface tensions. Consistent with this hypothesis, we observe a contact angle of a soft silicone substrate on rigid silica spheres that depends on the surface functionalization but not the sphere size. However, to satisfy this wetting condition without a divergent elastic stress, the gel phase separates from its solvent near the contact line. This creates a four-phase contact zone with two additional contact lines hidden below the surface of the substrate. Whereas the geometries of these contact lines are independent of the size of the sphere, the volume of the phase-separated region is not, but rather depends on the indentation volume. These results indicate that theories of adhesion of soft gels need to account for both the compressibility of the gel network and a nonzero surface stress between the gel and its solvent. PMID:26553989

  8. Adhesion enhancement in a biomimetic fibrillar interface.

    PubMed

    Glassmaker, Nicholas J; Jagota, Anand; Hui, Chung-Yuen

    2005-07-01

    Two important putative functions of the fibrillar contact interfaces commonly found in lizards and insects are to provide contact compliance and enhanced adhesion. To explore the question of whether a fibrillar architecture inherently enhances adhesion, we constructed model structures consisting of thin sheets of poly(vinyl butyral) (PVB) bonded on one of their thin sides to glass plates. The PVB samples had two flat, unstructured regions interrupted by a central fibrillar region along the bonded interface. The effect of the fibrillar geometry on the performance of the adhesive bond was tested using a tensile pull-off test, in which failure occurred by interfacial crack propagation, starting at an end where a crack initiator was introduced. We observed that fibrils in all samples fail consistently at the same critical stress, which is consistent with a previous theoretical result we have determined for flaw insensitivity during fibrillar pull-off. In addition, we measured the energy release rate required to fail the interface in the fibrillar region to be about an order of magnitude greater than that in the non-fibrillar region. We present experimental evidence demonstrating that this increase results partly from dissipation of strain energy stored in the fibrils.

  9. Development of Screenable Pressure Sensitive Adhesives

    SciTech Connect

    Steven J. Severtson

    2003-11-29

    An industrial research area of high activity in recent years has been the development of pressure sensitive adhesive (PSA) products that do not interfere with the processing of post-consumer waste. The problem of PSA contamination is arguably the most important technical challenge in expanding the use of recycled fiber. The presence of PSAs in recovered paper creates problems that reduce the efficiency of recycling and papermaking operations and diminish product quality. The widespread use of PSAs engineered to avoid these problems, often referred to as environmentally benign PSAs, could greatly increase the commercial viability of utilizing secondary fiber. Much of the research efforts in this area have focused on the development of PSAs that are designed for enhanced removal with cleaning equipment currently utilized by recycling plants. Most removal occurs at the pressure screens with the size and shape of residual contaminants in the process being the primary criteria for their separation. A viable approach for developing environmentally benign PSAs is their reformulation to inhibit fragmentation. The reduction of adhesives to small particles occurs almost exclusively during repulping; a process in which water and mechanical energy are used to swell and reduce paper products to their constituent fiber. Engineering PSA products to promote the formation of larger adhesive particles during repulping will greatly enhance their removal and reduce or eliminate their impact on the recycling process.

  10. Bovine leukocyte adhesion deficiency (BLAD): a review.

    PubMed

    Nagahata, Hajime

    2004-12-01

    Bovine leukocyte adhesion deficiency (BLAD) in Holstein cattle is an autosomal recessive congenital disease characterized by recurrent bacterial infections, delayed wound healing and stunted growth, and is also associated with persistent marked neutrophilia. The molecular basis of BLAD is a single point mutation (adenine to guanine) at position 383 of the CD18 gene, which caused an aspartic acid to glycine substitution at amino acid 128 (D128G) in the adhesion molecule CD18. Neutrophils from BLAD cattle have impaired expression of the beta2 integrin (CD11a,b,c/CD18) of the leukocyte adhesion molecule. Abnormalities in a wide spectrum of adherence dependent functions of leukocytes have been fully characterized. Cattle affected with BLAD have severe ulcers on oral mucous membranes, severe periodontitis, loss of teeth, chronic pneumonia and recurrent or chronic diarrhea. Affected cattle die at an early age due to the infectious complications. Holstein bulls, including carrier sires that had a mutant BLAD gene in heterozygote were controlled from dairy cattle for a decade. The control of BLAD in Holstein cattle by publishing the genotypes and avoiding the mating between BLAD carriers was found to be successful. This paper provides an overview of the genetic disease BLAD with reference to the disease in Holstein cattle.

  11. Adhesiveness of a new testosterone-in-adhesive matrix patch after extreme conditions.

    PubMed

    Raynaud, Jean-Pierre; Augès, Marie; Liorzou, Laurent; Turlier, Virginie; Lauze, Christophe

    2009-06-22

    The objective of the study was to evaluate the adhesiveness of a new thin, transparent and comfortable testosterone-in-adhesive matrix patch, Testopatch, after extreme conditions. The study was a single-centre, open-label with randomization of sites (upper arms, lower back, thighs) and sides (left, right) of two 45 cm(2) patches, in 24 healthy subjects. Patches were symmetrically applied on one of the three sites. One patch was removed after 2.0 h, under resting conditions and the other patch was removed at 3.5 h, after extreme conditions (physical exercise, sauna, whirl bath). Adhesiveness was assessed of the area stuck and the measure of the forces necessary for patch removal using a Peel Patch Tester. Local safety was assessed at 2.0 and 3.5 h. After physical exercise and after sauna, patch adhesiveness was excellent (95%) when applied on the thigh and very good (90%) on the upper arm. Forces of patch removal were significantly lower at 3.5 h than 2.0 h, and at the lower back compared to the other application sites. There were no adverse effects. Slight erythema was observed that was considered to be clinically insignificant. Testopatch was safe and displayed adhesiveness, compatible with physical activities.

  12. Focal adhesion kinase modulates tension signaling to control actin and focal adhesion dynamics.

    PubMed

    Schober, Markus; Raghavan, Srikala; Nikolova, Maria; Polak, Lisa; Pasolli, H Amalia; Beggs, Hilary E; Reichardt, Louis F; Fuchs, Elaine

    2007-02-26

    In response to alphabeta1 integrin signaling, transducers such as focal adhesion kinase (FAK) become activated, relaying to specific machineries and triggering distinct cellular responses. By conditionally ablating Fak in skin epidermis and culturing Fak-null keratinocytes, we show that FAK is dispensable for epidermal adhesion and basement membrane assembly, both of which require alphabeta1 integrins. FAK is also dispensible for proliferation/survival in enriched medium. In contrast, FAK functions downstream of alphabeta1 integrin in regulating cytoskeletal dynamics and orchestrating polarized keratinocyte migration out of epidermal explants. Fak-null keratinocytes display an aberrant actin cytoskeleton, which is tightly associated with robust, peripheral focal adhesions and microtubules. We find that without FAK, Src, p190RhoGAP, and PKL-PIX-PAK, localization and/or activation at focal adhesions are impaired, leading to elevated Rho activity, phosphorylation of myosin light chain kinase, and enhanced tensile stress fibers. We show that, together, these FAK-dependent activities are critical to control the turnover of focal adhesions, which is perturbed in the absence of FAK.

  13. Modeling material interfaces with hybrid adhesion method

    DOE PAGES

    Brown, Nicholas Taylor; Qu, Jianmin; Martinez, Enrique

    2017-01-27

    A molecular dynamics simulation approach is presented to approximate layered material structures using discrete interatomic potentials through classical mechanics and the underlying principles of quantum mechanics. This method isolates the energetic contributions of the system into two pure material layers and an interfacial region used to simulate the adhesive properties of the diffused interface. The strength relationship of the adhesion contribution is calculated through small-scale separation calculations and applied to the molecular surfaces through an inter-layer bond criterion. By segregating the contributions into three regions and accounting for the interfacial excess energies through the adhesive surface bonds, it is possiblemore » to model each material with an independent potential while maintaining an acceptable level of accuracy in the calculation of mechanical properties. This method is intended for the atomistic study of the delamination mechanics, typically observed in thin-film applications. Therefore, the work presented in this paper focuses on mechanical tensile behaviors, with observations in the elastic modulus and the delamination failure mode. To introduce the hybrid adhesion method, we apply the approach to an ideal bulk copper sample, where an interface is created by disassociating the force potential in the middle of the structure. Various mechanical behaviors are compared to a standard EAM control model to demonstrate the adequacy of this approach in a simple setting. In addition, we demonstrate the robustness of this approach by applying it on (1) a Cu-Cu2O interface with interactions between two atom types, and (2) an Al-Cu interface with two dissimilar FCC lattices. These additional examples are verified against EAM and COMB control models to demonstrate the accurate simulation of failure through delamination, and the formation and propagation of dislocations under loads. Finally, the results conclude that by modeling the energy

  14. Urethane/Silicone Adhesives for Bonding Flexing Metal Parts

    NASA Technical Reports Server (NTRS)

    Edwards, Paul D.

    2004-01-01

    Adhesives that are blends of commercially available urethane and silicone adhesives have been found to be useful for bonding metal parts that flex somewhat during use. These urethane/silicone adhesives are formulated for the specific metal parts to be bonded. The bonds formed by these adhesives have peel and shear strengths greater than those of bonds formed by double-sided tapes and by other adhesives, including epoxies and neat silicones. In addition, unlike the bonds formed by epoxies, the bonds formed by these adhesives retain flexibility. In the initial application for which the urethane/silicone adhesives were devised, there was a need to bond spring rings, which provide longitudinal rigidity for inflatable satellite booms, with the blades that provide the booms axial strength. The problem was to make the bonds withstand the stresses, associated with differences in curvature between the bonded parts, that arose when the booms were deflated and the springs were compressed. In experiments using single adhesives (that is, not the urethane/ silicone blends), the bonds were broken and, in each experiment, it was found that the adhesive bonded well with either the ring or with the blade, but not both. After numerous experiments, the adhesive that bonded best with the rings and the adhesive that bonded best with the blades were identified. These adhesives were then blended and, as expected, the blend bonded well with both the rings and the blades. The two adhesives are Kalex (or equivalent) high-shear-strength urethane and Dow Corning 732 (or equivalent) silicone. The nominal mixture ratio is 5 volume parts of the urethane per 1 volume part of the silicone. Increasing the proportion of silicone makes the bond weaker but more flexible, and decreasing the proportion of silicone makes the bond stronger but more brittle. The urethane/silicone blend must be prepared and used quickly because of the limited working time of the urethane: The precursor of the urethane

  15. Plasma treated polyethylene grafted with adhesive molecules for enhanced adhesion and growth of fibroblasts.

    PubMed

    Rimpelová, Silvie; Kasálková, Nikola Slepičková; Slepička, Petr; Lemerová, Helena; Švorčík, Václav; Ruml, Tomáš

    2013-04-01

    The cell-material interface plays a crucial role in the interaction of cells with synthetic materials for biomedical use. The application of plasma for tailoring polymer surfaces is of abiding interest and holds a great promise in biomedicine. In this paper, we describe polyethylene (PE) surface tuning by Ar plasma irradiating and subsequent grafting of the chemically active PE surface with adhesive proteins or motives to support cell attachment. These simple modifications resulted in changed polymer surface hydrophilicity, roughness and morphology, which we thoroughly characterized. The effect of our modifications on adhesion and growth was tested in vitro using mouse embryonic fibroblasts (NIH 3T3 cell line). We demonstrate that the plasma treatment of PE had a positive effect on the adhesion, spreading, homogeneity of distribution and moderately on proliferation activity of NIH 3T3 cells. This effect was even more pronounced on PE coated with biomolecules.

  16. Fibrillar adhesion with no clusterisation: Functional significance of material gradient along adhesive setae of insects.

    PubMed

    Gorb, Stanislav N; Filippov, Alexander E

    2014-01-01

    It has been recently demonstrated that adhesive tarsal setae of beetles possess material gradients along their length. These gradients presumably represent an evolutionary optimization enhancing the adaptation to rough surfaces while simultaneously preventing clusterisation of the setae by lateral collapse. The numerical experiment of the present study has clearly demonstrated that gradient-bearing fibers with short soft tips and stiff bases have greater advantage in maximizing adhesion and minimizing clusterisation in multiple attachment-detachment cycles, if compared to the fibers with longer soft tips on the stiff bases and fibers with stiff tips on the soft bases. This study not only manifests the crucial role of gradients in material properties along the setae in beetle fibrillar adhesive system, but predicts that similar gradients must have been convergently evolved in various lineages of arthropods.

  17. Rocking adhesion assay system to study adhesion and transendothelial migration of cancer cells.

    PubMed

    Bapu, Deepashree; Khadim, Munira; Brooks, Susan A

    2014-01-01

    Adhesion of metastatic cancer cells to the vascular endothelium of the target organs and their subsequent transendothelial migration is one of the critical, yet poorly understood, steps of the metastatic cascade. Conventionally, the mechanisms of this complex process have been studied using static adhesion systems or flow assay systems. Static assay systems are easy to set up and perform but do not mimic the physiological conditions of blood flow. Flow assays closely mimic physiological conditions of flow but are time consuming and require specialist equipment. In this chapter we describe the rocking adhesion system which incorporates the key advantages of both the static and flow assay systems and not only is easy to set up and perform but also mimics conditions of blood flow.

  18. Structural Evaluation of the RSRM Nozzle Replacement Adhesive

    NASA Technical Reports Server (NTRS)

    Batista-Rodriguez, A.; McLennan, M. L.; Palumbos, A. V.; Richardson, D. E.

    1999-01-01

    This paper describes the structural performance evaluation of a replacement adhesive for the Reusable Solid Rocket Motor (RSRM) nozzle utilizing finite element analysis. Due to material obsolescence and industrial safety issues, the two current structural adhesives, EA 913 and EA 946 are to be replaced with a new adhesive. TIGA 321. The structural evaluation in support of the adhesive replacement effort includes residual stress, transportation, and flight analyses. Factors of safety are calculated using the stress response from each analysis. The factors of safety are used as the limiting criteria to compare the replacement adhesive against the current adhesives. Included in this paper are the analytical approach, assumptions and modeling techniques as well as the results of the evaluation. An important factor to the evaluation is the similarity in constitutive material properties (elastic modulus and Poisson's ratio) between TIGA 321 and EA 913. This similarity leads to equivalent material response from the two adhesives. However, TIGA 321 surpasses EA 913's performance due to higher material capabilities. Conversely, the change in stress response from EA 946 to TIGA 321 is more apparent: this is primarily attributed to the difference in the modulii of the two adhesives, which differ by two orders of magnitude. The results of the bondline evaluation indicate that the replacement adhesive provides superior performance than the current adhesives with only minor exceptions. Furthermore, TIGA 321 causes only a minor chance in the response of the phenolic and metal components.

  19. The chemistry of stalked barnacle adhesive (Lepas anatifera)

    PubMed Central

    Jonker, Jaimie-Leigh; Morrison, Liam; Lynch, Edward P.; Grunwald, Ingo; von Byern, Janek; Power, Anne Marie

    2015-01-01

    The results of the first chemical analysis of the adhesive of Lepas anatifera, a stalked barnacle, are presented. A variety of elements were identified in scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) of the adhesive, including Na, Mg, Ca, Cl, S, Al, Si, K and Fe; however, protein–metal interactions were not detected in Raman spectra of the adhesive. Elemental signatures from SEM-EDS of L. anatifera adhesive glands were less varied. Phosphorous was mostly absent in adhesive samples; supporting previous studies showing that phosphoserines do not play a significant role in adult barnacle adhesion. Disulfide bridges arising from Cys dimers were also investigated; Raman analysis showed weak evidence for S–S bonds in L. anatifera. In addition, there was no calcium carbonate signal in the attenuated total reflectance Fourier transform infrared spectra of L. anatifera adhesive, unlike several previous studies in other barnacle species. Significant differences were observed between the Raman spectra of L. anatifera and Balanus crenatus; these and a range of Raman peaks in the L. anatifera adhesive are discussed. Polysaccharide was detected in L. anatifera adhesive but the significance of this awaits further experiments. The results demonstrate some of the diversity within barnacle species in the chemistry of their adhesives. PMID:25657841

  20. Mechanical behavior of adhesive joints subjected to cyclic thermal loading

    SciTech Connect

    Humfeld, G.R.; Dillard, D.A.

    1996-12-31

    Stresses induced in bimaterial systems due to changing temperature has been the subject of much study since the publication of Timoshenko`s classic paper of 1925. An adhesive bond is one example of a bimaterial system in which thermal stress can play an important role. However, adhesives are viscoelastic in nature, and their mechanical behavior is dictated by the temperature- and time-dependence of their material properties; analytical solutions for elastic materials do not adequately describe their true behavior. The effect of the adhesive`s viscoelasticity on stress in an adhesive bond subjected to changing temperature is therefore of compelling interest and importance for the adhesives industry. The objective of this research is to develop an understanding of the viscoelastic effect in an adhesive bond subjected to cycling temperature, particularly when the temperature range spans a transition temperature of the adhesive. Numerical modeling of a simplified geometry was first undertaken to isolate the influence of viscoelasticity on the stress state from any particular specimen geometry effect. Finite element modeling was then undertaken to examine the mechanical behavior of the adhesive in a layered geometry. Both solution methods predicted development of residual tensile stresses in the adhesive. For the layered geometry this was found to correspond with residual tensile peel stresses, which are thought to be the cause of interfacial debonding.

  1. A bioinspired wet/dry microfluidic adhesive for aqueous environments.

    PubMed

    Majumder, Abhijit; Sharma, Ashutosh; Ghatak, Animangsu

    2010-01-05

    A pressure-sensitive, nonreacting and nonfouling adhesive which can perform well both in air and underwater is very desirable because of its potential applications in various settings such as biomedical, marine, and automobile. Taking a clue from nature that many natural adhesive pads have complex structures underneath the outer adhesive layer, we have prepared thin elastic adhesive films with subsurface microstructures using PDMS (poly(dimethylsiloxane)) and investigated their performance underwater. The presence of embedded structure enhances the energy of adhesion considerably both in air and underwater. Furthermore, filling the channels with liquid of suitable surface tension modifies the internal stress profile, resulting into significant enhancement in adhesive performance. As this increase in adhesion is mediated by mechanics and not by surface chemistry, the presence of water does not alter its performance much. For the same reason, this adhesion mechanism works with both hydrophobic and hydrophilic surfaces. The adhesive can be reused because of its elastic surface. Moreover, unlike many other present-day adhesives, its performance does not decrease with time.

  2. The chemistry of stalked barnacle adhesive (Lepas anatifera).

    PubMed

    Jonker, Jaimie-Leigh; Morrison, Liam; Lynch, Edward P; Grunwald, Ingo; von Byern, Janek; Power, Anne Marie

    2015-02-06

    The results of the first chemical analysis of the adhesive of Lepas anatifera, a stalked barnacle, are presented. A variety of elements were identified in scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) of the adhesive, including Na, Mg, Ca, Cl, S, Al, Si, K and Fe; however, protein-metal interactions were not detected in Raman spectra of the adhesive. Elemental signatures from SEM-EDS of L. anatifera adhesive glands were less varied. Phosphorous was mostly absent in adhesive samples; supporting previous studies showing that phosphoserines do not play a significant role in adult barnacle adhesion. Disulfide bridges arising from Cys dimers were also investigated; Raman analysis showed weak evidence for S-S bonds in L. anatifera. In addition, there was no calcium carbonate signal in the attenuated total reflectance Fourier transform infrared spectra of L. anatifera adhesive, unlike several previous studies in other barnacle species. Significant differences were observed between the Raman spectra of L. anatifera and Balanus crenatus; these and a range of Raman peaks in the L. anatifera adhesive are discussed. Polysaccharide was detected in L. anatifera adhesive but the significance of this awaits further experiments. The results demonstrate some of the diversity within barnacle species in the chemistry of their adhesives.

  3. Adhesive and Elastic Properties of DOPA-Containing Hydrogels

    NASA Astrophysics Data System (ADS)

    Webber, Rebecca; Shull, Ken; Messersmith, Phillip; Madhav, Priti

    2001-03-01

    It was recently determined that L-3,4-dihydroxyphenylalanine (DOPA) is primarily responsible for both the adhesion and crosslinking that occurs in mussel adhesive proteins (MAPs). In wet environments, MAPs form strong adhesive bonds to a large variety of substrates, making DOPA-modified polymers very interesting for adhesion studies. Polymer materials modified from or modeled after DOPA have large potential as biomedical adhesives and as adhesives in aqueous environments. The mechanical and adhesive properties of a DOPA-containing hydrogel were tested using an axisymmetric adhesion test modified from the method of Johnson, Kendall and Roberts. In accordance with this technique, a rigid, hemispherical indenter was brought into contact with hydrogel samples, generating load and displacement data. In addition, images were taken of the contact between the sample and indenter. Using the collected data and images, the adhesive properties of the material were calculated. Separate experiments were conducted in conditions of varying humidity and aqueous environments in order to determine any changes in the adhesive behavior of the hydrogel. Data resulting from experiments in each type of environment will be presented.

  4. Analysis of Adhesion Molecules and Basement Membrane Contributions to Synaptic Adhesion at the Drosophila Embryonic NMJ

    PubMed Central

    Koper, Andre; Schenck, Annette; Prokop, Andreas

    2012-01-01

    Synapse formation and maintenance crucially underlie brain function in health and disease. Both processes are believed to depend on cell adhesion molecules (CAMs). Many different classes of CAMs localise to synapses, including cadherins, protocadherins, neuroligins, neurexins, integrins, and immunoglobulin adhesion proteins, and further contributions come from the extracellular matrix and its receptors. Most of these factors have been scrutinised by loss-of-function analyses in animal models. However, which adhesion factors establish the essential physical links across synaptic clefts and allow the assembly of synaptic machineries at the contact site in vivo is still unclear. To investigate these key questions, we have used the neuromuscular junction (NMJ) of Drosophila embryos as a genetically amenable model synapse. Our ultrastructural analyses of NMJs lacking different classes of CAMs revealed that loss of all neurexins, all classical cadherins or all glutamate receptors, as well as combinations between these or with a Laminin deficiency, failed to reveal structural phenotypes. These results are compatible with a view that these CAMs might have no structural role at this model synapse. However, we consider it far more likely that they operate in a redundant or well buffered context. We propose a model based on a multi-adaptor principle to explain this phenomenon. Furthermore, we report a new CAM-independent adhesion mechanism that involves the basement membranes (BM) covering neuromuscular terminals. Thus, motorneuronal terminals show strong partial detachment of the junction when BM-to-cell surface attachment is impaired by removing Laminin A, or when BMs lose their structural integrity upon loss of type IV collagens. We conclude that BMs are essential to tie embryonic motorneuronal terminals to the muscle surface, lending CAM-independent structural support to their adhesion. Therefore, future developmental studies of these synaptic junctions in Drosophila need

  5. Improving adhesion of seasonings to crackers with hydrocolloid solutions.

    PubMed

    Armstrong, Matthew E; Barringer, Sheryl A

    2013-11-01

    Food powders were applied on crackers that had been coated using water, oil, emulsion, sucrose, or hydrocolloid solutions. The hydrocolloids that were used include gellan gum, kappa-carrageenan, methylcellulose, gum karaya, gum tragacanth, gum arabic, guar gum, modified starch, and maltodextrin. Solutions of similar hydrophobicity to the powder gave the greatest adhesion. NaCl, barbecue (BBQ), ranch, and sour cream & onion (SC&O) seasoning showed greatest adhesion with water, cheese powder with an emulsion of 12.5% to 25% oil, and cocoa powder with oil. For NaCl, BBQ, ranch, and SC&O seasoning, hydrocolloids improved the adhesion over using water alone, with gellan gum providing the greatest adhesion. Hydrocolloid structural differences, including the presence or absence of branching, substitution of sugar units, and molecular weight affect water binding and thickening of the hydrocolloid spray that seemed to be significant factors affecting adhesion of powders to the target surface. For cheese powder, hydrocolloids were capable of replacing the oil within an emulsion while improving or maintaining the same level of adhesion, with gum arabic providing the greatest adhesion. For cocoa powder, hydrocolloid solutions were ineffective adhesives due to differences in hydrophilicity that result in insolubility. The effect of hydrocolloid concentration on adhesion was dependent both on the hydrocolloid type and the concentration that is sprayable, with 0.5% being the optimum concentration for most gums. Adhesion using sucrose solutions was determined by particle size and relative hydrophobicity. Increasing sucrose concentration decreased adhesion of smaller particles, but increased adhesion of larger particles. Adhesion of NaCl significantly increased with decreasing NaCl size using oil, water, and sucrose solutions.

  6. Modified Surface Having Low Adhesion Properties to Mitigate Insect Residue Adhesion

    NASA Technical Reports Server (NTRS)

    Wohl, Christopher J., Jr. (Inventor); Smith, Joseph G., Jr. (Inventor); Siochi, Emilie J. (Inventor); Penner, Ronald K. (Inventor)

    2016-01-01

    A process to modify a surface to provide reduced adhesion surface properties to mitigate insect residue adhesion. The surface may include the surface of an article including an aircraft, an automobile, a marine vessel, all-terrain vehicle, wind turbine, helmet, etc. The process includes topographically and chemically modifying the surface by applying a coating comprising a particulate matter, or by applying a coating and also topographically modifying the surface by various methods, including but not limited to, lithographic patterning, laser ablation and chemical etching, physical vapor phase deposition, chemical vapor phase deposition, crystal growth, electrochemical deposition, spin casting, and film casting.

  7. Primary Adhesively Bonded Structure Technology (PABST). Design Handbook for Adhesive Bonding

    DTIC Science & Technology

    1979-11-01

    47 EFFECT OF MOISTURE IN ADHESIVE ON BOND STRESS DISTRIBUTIONS 95 The use of adhesive to fill up the gaps where parts don’t fit is incompatible with...cap and web and chamfer tht base as shown in Figure 72? If the longeron ends adjacent to another member, which is often the case, the gap between the... to2 ) EVALUATE X4 AT TEMPERATURE GIVING LEAST VALUE - AGAIN, THE HOTTEST OPTIMUM OVERLAP = Rp + I’uY(NO GREATER OVERLAP CAN INCREASE JOINT STRENGTH

  8. Enhancing Adhesion: Relative Merits of Different Approaches

    NASA Technical Reports Server (NTRS)

    Penn, L. S.; Pater, R.

    1996-01-01

    Adhesive performance is improved mainly by manipulation of the bimaterials interface zone, which is only a few molecules thick. There are three approaches to enhancement of interfacial adhesion at the molecular level. They are 1) changing the nonchemically bonded interactions across the interface from weak ones to strong ones, 2) making the true interfacial area much larger than the simple geometric area, and 3) inducing chemical bonding between the two materials forming the interface. Our goal this summer was to question some of the built-in assumptions contained within these approaches and to determine the most promising approach, both theoretically and practically, for enhancing adhesion in NASA structures. Our computations revealed that all three of these approaches have, in theory, the potential to enhance molecular adhesion approximately ten-fold. Experiments, however, revealed that this excellent level of enhancement is not likely to be reached in practice. Each approach was found to be severely limited by practical problems. In addition, some of the built-in assumptions associated with these approaches were found to be insufficient or inadequate. The first approach, changing the nonchemically bonded interactions from weak to strong, Is an example of one containing inadequate assumptions. The extensive literature on intermolecular interactions, based on solution studies, shows that certain functional group pairs interact much more strongly than others. It has always been assumed that these data can be reliably extended to systems where only one member of the pair is in solution and the other Is contained in a solid surface. Our experiments this summer demonstrated that solution data do not adequately predict the strength of functional group interaction at the solid-liquid interface. Furthermore, the strong solvents needed to dissolve the monomers or polymers to which the functional groups of interest are attached compete successfully with the solid surface

  9. Elastic-plastic analysis of crack in ductile adhesive joint

    SciTech Connect

    Ikeda, Toru; Miyazaki, Noriyuki; Yamashita, Akira; Munakata, Tsuyoshi

    1995-11-01

    The fracture of a crack in adhesive is important to the structural integrity of adhesive structures and composite materials. Though the fracture toughness of a material should be constant according to fracture mechanics, it is said that the fracture toughness of a crack in an adhesive joint depends on the bond thickness. In the present study, the elastic-plastic stress analyses of a crack in a thin adhesive layer are performed by the combination of the boundary element method and the finite element method. The effect of adhesive thickness on the J-integral, the Q`-factor which is a modified version of the Q-factor, and the crack tip opening displacement (CTOD) are investigated. It is found from the analyses that the CTOD begins to decrease at very thin bond thickness, the Q`-factor being almost constant. The decrease of the fracture toughness at very thin adhesive layer is expected by the present analysis.

  10. Thermophysical and flammability characterization of phosphorylated epoxy adhesives

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Parker, J. A.; Giants, T. W.; Bilow, N.; Hsu, M.-T.

    1980-01-01

    Some of the thermophysical and flammability properties of a phosphorylated epoxy adhesive, which has potential applications in aircraft interior panels, are described. The adhesive consists of stoichiometric ratios of bis(3-glycidyloxphenyl)methylphosphine oxide and bis(3-aminophenyl)methylphosphine oxide containing approximately 7.5% phosphorus. Preliminary data are presented from adhesive bonding studies conducted utilizing this adhesive with polyvinyl fluoride (PVF) film and phenolic-glass laminates. Limiting oxygen index and smoke density data are presented and compared with those of the tetraglycidyl methylene dianiline epoxy resin-adhesive system currently used in aircraft interiors. Initial results indicate that the phosphorylated epoxy compound has excellent adhesive properties when used with PVF film and that desirable fire-resistant properties are maintained.

  11. Cryogenic/high temperature structural adhesives. [for space shuttles

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Sheppard, C. H.

    1974-01-01

    Results are described of the work performed to develop a structural adhesive system which possesses useful properties over a 20K (-423 F) to 589 K (600 F) temperature range. Adhesives systems based on polyimide, polyphenylquinoxaline polyquinoxaline, polybenzothiazole and polybenzimidazole polymers first were screened for suitability. Detailed evaluation of two polyimide adhesive sytems, Br34/FM34 and P4/A5F or P4A/A5FA, and one polyphenylquinoxaline adhesive system, PPQ II (IMW), then was performed. Property information was generated over the full temperature range for shear strength, stressed and unstressed thermal aging, thermal shock and coefficient of thermal expansion. Both polyimide adhesive systems were identified as being capable of providing structural adhesive joints for cryogenic/high temperature service.

  12. Endothelial tetraspanin microdomains regulate leukocyte firm adhesion during extravasation.

    PubMed

    Barreiro, Olga; Yáñez-Mó, María; Sala-Valdés, Mónica; Gutiérrez-López, María Dolores; Ovalle, Susana; Higginbottom, Adrian; Monk, Peter N; Cabañas, Carlos; Sánchez-Madrid, Francisco

    2005-04-01

    Tetraspanins associate with several transmembrane proteins forming microdomains involved in intercellular adhesion and migration. Here, we show that endothelial tetraspanins relocalize to the contact site with transmigrating leukocytes and associate laterally with both intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Alteration of endothelial tetraspanin microdomains by CD9-large extracellular loop (LEL)-glutathione S-transferase (GST) peptides or CD9/CD151 siRNA oligonucleotides interfered with ICAM-1 and VCAM-1 function, preventing lymphocyte transendothelial migration and increasing lymphocyte detachment under shear flow. Heterotypic intercellular adhesion mediated by VCAM-1 or ICAM-1 was augmented when expressed exogenously in the appropriate tetraspanin environment. Therefore, tetraspanin microdomains have a crucial role in the proper adhesive function of ICAM-1 and VCAM-1 during leukocyte adhesion and transendothelial migration.

  13. Adhesion as an interplay between particle size and surface roughness.

    PubMed

    Katainen, J; Paajanen, M; Ahtola, E; Pore, V; Lahtinen, J

    2006-12-15

    Surface roughness plays an important role in the adhesion of small particles. In this paper we have investigated adhesion as a geometrical effect taking into account both the particle size and the size of the surface features. Adhesion is studied using blunt model particles on surfaces up to 10 nm root-mean-square (RMS) roughness. Measurements with particles both smaller and larger than surface features are presented. Results indicate different behavior in these areas. Adhesion of particles smaller than or similar in size to the asperities depend mainly on the size and shape of the asperities and only weakly on the size of the particle. For large particles also the particle size has a significant effect on the adhesion. A new model, which takes the relative size of particles and asperities into account, is also derived and compared to the experimental data. The proposed model predicts adhesion well over a wide range of particle/asperity length scales.

  14. Adhesion of mussel foot proteins to different substrate surfaces

    PubMed Central

    Lu, Qingye; Danner, Eric; Waite, J. Herbert; Israelachvili, Jacob N.; Zeng, Hongbo; Hwang, Dong Soo

    2013-01-01

    Mussel foot proteins (mfps) have been investigated as a source of inspiration for the design of underwater coatings and adhesives. Recent analysis of various mfps by a surface forces apparatus (SFA) revealed that mfp-1 functions as a coating, whereas mfp-3 and mfp-5 resemble adhesive primers on mica surfaces. To further refine and elaborate the surface properties of mfps, the force–distance profiles of the interactions between thin mfp (i.e. mfp-1, mfp-3 or mfp-5) films and four different surface chemistries, namely mica, silicon dioxide, polymethylmethacrylate and polystyrene, were measured by an SFA. The results indicate that the adhesion was exquisitely dependent on the mfp tested, the substrate surface chemistry and the contact time. Such studies are essential for understanding the adhesive versatility of mfps and related/similar adhesion proteins, and for translating this versatility into a new generation of coatings and (including in vivo) adhesive materials. PMID:23173195

  15. Molecular markers of cell adhesion in ameloblastomas. An update

    PubMed Central

    González-González, Rogelio; Molina-Frechero, Nelly; Damian-Matsumura, Pablo

    2014-01-01

    Ameloblastoma is the most common odontogenic tumor of epithelial origin, and though it is of a benign nature, it frequently infiltrates the bone, has a high rate of recurrence and could potentially become malignant. Cellular adhesion potentially plays an important role in the manifestation of these characteristics and in the tumor biology of ameloblastomas. Losses of cell-cell and extracellular matrix adhesion and cohesion are among the first events that occur in the invasion and growth of tumors of epithelial origin. The present review includes a description of the molecules that are involved in cell adhesion as reported for various types of ameloblastomas and discusses the possible roles of these molecules in the biological behaviors of this odontogenic tumor. Knowledge of the complex mechanisms in which these molecules play a role is critical for the research and discovery of future therapeutic targets. Key words:Ameloblastoma, cellular adhesion, molecular markers, cell-cell adhesion, extracellular matrix-cell adhesion. PMID:23986011

  16. Joining veneers to ceramic cores and dentition with adhesive interlayers.

    PubMed

    Lee, J J-W; Wang, Y; Lloyd, I K; Lawn, B R

    2007-08-01

    Adhesive joining of veneers to cores offers potential simplicity and economy in the fabrication of all-ceramic crowns. We tested the hypothesis that resin-based adhesives can be used for such fabrication without compromising mechanical integrity of the crown structure. A simple test procedure for quantifying this hypothesis was proposed. A model glass veneer layer 1 mm thick (representative of porcelain), adhesively bonded onto a glass-like core substrate (ceramic or dental enamel), was loaded at its top surface with a hard sphere (occlusal force) until a radial crack initiated at the veneer undersurface. The critical loads for fracture, visually observable in the transparent glass, afforded a measure of the predisposition for the adhesive to cause veneer failure in an occlusal overload. Two adhesives were tested, one a commercial epoxy resin and the other a relatively stiff in-house-developed composite. The results confirmed that stiffer adhesives provide higher resistance to failure.

  17. Intrinsic adhesion force of lubricants to steel surface.

    PubMed

    Lee, Jonghwi

    2004-09-01

    The intrinsic adhesion forces of lubricants and other pharmaceutical materials to a steel surface were quantitatively compared using Atomic Force Microscopy (AFM). A steel sphere was attached to the tip of an AFM cantilever, and its adhesion forces to the substrate surfaces of magnesium stearate, sodium stearyl fumarate, lactose, 4-acetamidophenol, and naproxen were measured. Surface roughness varied by an order of magnitude among the materials. However, the results clearly showed that the two lubricants had about half the intrinsic adhesion force as lactose, 4-acetamidophenol, and naproxen. Differences in the intrinsic adhesion forces of the two lubricants were insignificant. The lubricant molecules were unable to cover the steel surface during AFM measurements. Intrinsic adhesion force can slightly be modified by surface treatment and compaction, and its tip-to-tip variation was not greater than its difference between lubricants and other pharmaceutical particles. This study provides a quantitative fundamental basis for understanding adhesion related issues.

  18. Applicability of DNA analysis on adhesive tape in forensic casework.

    PubMed

    Zech, Wolf-Dieter; Malik, Naseem; Thali, Michael

    2012-07-01

    Adhesive tape is commonly used in crimes and is often the subject of forensic evaluation. DNA analysis of adhesive tape can provide DNA profiles of suspects. The object of this study was to evaluate the applicability of DNA analysis on adhesive tape samples in forensic casework. We retrospectively reviewed all cases involving adhesive tape or similar items received by our institute for DNA analysis during the past 11 years. From 100 forensic cases reviewed, 150 adhesive tape samples were examined. A total of 98 DNA profiles were obtained from these samples. Sixty-two of the profiles provided feasible case-relevant information. In conclusion, DNA profiling of adhesive tape samples can be useful in a variety of forensic cases.

  19. Ultrasonic Evaluation of Thermal Degradation in Adhesive Bonds

    NASA Technical Reports Server (NTRS)

    Lih, Shyh-Shiuh; Mal, Ajit K.; Bar-Cohen, Yoseph

    1994-01-01

    The critical role played by adhesive bonds in lap joints is well known. A good knowledge of the mechanical properties of adhesive bonds in lap joints is a prerequisite to the design and reliable prediction of the performance of these bonded structures. Furthermore, the lap joint may be subject to high-temperature environments in service. Early detection of the degree of thermal degradation in adhesive bonds is required under these circumstances. A variety of ultrasonic nondestructive evaluation (NDE) techniques can be used to determine the thickness and the elastic moduli of adhesively bonded joints. In this paper we apply a previously developed technique based on the leaky Lamb wave (LLW) experiment to investigate the possibility of characterizing the thermal degradation of adhesive bonds in lap joints. The degradation of the adhesive bonds is determined through comparison between experimental data and theoretical calculations.

  20. Ultrasonic Nondestructive Characterization of Adhesive Bonds

    NASA Technical Reports Server (NTRS)

    Qu, Jianmin

    1997-01-01

    Qualitative measurements of adhesion or binding forces can be accomplished, for example, by using the reflection coefficient of an ultrasound or by using thermal waves (Light and Kwun, 1989, Achenbach and Parikh, 1991, and Bostrom and wickham, 1991). However, a quantitative determination of binding forces is rather difficult. It has been observed that higher harmonics of the fundamental frequency are generated when an ultrasound passes through a nonlinear material. It seems that such non-linearity can be effectively used to characterize the bond strength. Several theories have been developed to model this nonlinear effect (Adler and Nagy, 1991; Achenbach and Parikh, 1991; Parikh and Achenbach, 1992; and Hirose and Kitahara, 1992; Anastasi and Roberts, 1992). Based on a microscopic description of the nonlinear interface binding force, a quantitative method was presented by Pangraz and Arnold (1994). Recently, Tang, Cheng and Achenbach (1997) made a comparison between the experimental and simulated results based on this theoretical model. A water immersion mode-converted shear wave through-transmission setup was used by Berndt and Green (1997) to analyze the nonlinear acoustic behavior of the adhesive bond. In this project, the nonlinear responses of an adhesive joint was investigated through transmission tests of ultrasonic wave and analyzed by the finite element simulations. The higher order harmonics were obtained in the tests. It is found that the amplitude of higher harmonics increases as the aging increases, especially the 3dorder harmonics. Results from the numerical simulation show that the material nonlinearity does indeed generate higher order harmonics. In particular, the elastic-perfect plastic behavior generates significant 3rd and 5th order harmonics.

  1. Bonding Durability of Four Adhesive Systems

    PubMed Central

    Seyed Tabai, Elaheh; Mohammadi Basir, Mahshid

    2015-01-01

    Objectives: This study aimed to compare the durability of four adhesive systems by assessing their microtensile bond strength (MTBS) and microleakage during six months of water storage. Materials and Methods: A total of 128 human third molars were used. The adhesives tested were Scotch Bond Multipurpose (SBMP), Single Bond (SB), Clearfil-SE bond (CSEB), and All-Bond SE (ABSE). After sample preparation for MTBS testing, the microspecimens were subjected to microtensile tester after one day and six months of water storage. For microleakage evaluation, facial and lingual class V cavities were prepared and restored with composite. After thermocycling, microleakage was evaluated. Bond strength values were subjected to one-way ANOVA and Tamhane’s test, and the microleakage data were analyzed by the Kruskal-Wallis, Dunn, Mann Whitney and Wilcoxon tests (P<0.05). Results: Single Bond yielded the highest and ABSE yielded the lowest bond strength at one day and six months. Short-term bond strength of SBMP and CSEB was similar. After six months, a significant decrease in bond strength was observed in ABSE and SBMP groups. At one day, ABSE showed the highest microleakage at the occlusal margin; however, at the gingival margin, there was no significant difference among groups. Long-term microleakage of all groups at the occlusal margins was similar, whilst gingival margins of SBMP and SB showed significantly higher microleakage. Conclusion: The highest MTBS and favorable sealability were obtained by Clearfil SE bond. Water storage had no effect on microleakage of self-etch adhesives at the gingival margin or MTBS of CSEB and SB. PMID:27123015

  2. Nanomechanics controls neuronal precursors adhesion and differentiation.

    PubMed

    Migliorini, Elisa; Ban, Jelena; Grenci, Gianluca; Andolfi, Laura; Pozzato, Alessandro; Tormen, Massimo; Torre, Vincent; Lazzarino, Marco

    2013-08-01

    The ability to control the differentiation of stem cells into specific neuronal types has a tremendous potential for the treatment of neurodegenerative diseases. In vitro neuronal differentiation can be guided by the interplay of biochemical and biophysical cues. Different strategies to increase the differentiation yield have been proposed, focusing everything on substrate topography, or, alternatively on substrate stiffness. Both strategies demonstrated an improvement of the cellular response. However it was often impossible to separate the topographical and the mechanical contributions. Here we investigate the role of the mechanical properties of nanostructured substrates, aiming at understanding the ultimate parameters which govern the stem cell differentiation. To this purpose a set of different substrates with controlled stiffness and with or without nanopatterning are used for stem cell differentiation. Our results show that the neuronal differentiation yield depends mainly on the substrate mechanical properties while the geometry plays a minor role. In particular nanostructured and flat polydimethylsiloxane (PDMS) substrates with comparable stiffness show the same neuronal yield. The improvement in the differentiation yield obtained through surface nanopatterning in the submicrometer scale could be explained as a consequence of a substrate softening effect. Finally we investigate by single cell force spectroscopy the neuronal precursor adhesion on the substrate immediately after seeding, as a possible critical step governing the neuronal differentiation efficiency. We observed that neuronal precursor adhesion depends on substrate stiffness but not on surface structure, and in particular it is higher on softer substrates. Our results suggest that cell-substrate adhesion forces and mechanical response are the key parameters to be considered for substrate design in neuronal regenerative medicine.

  3. Strength of adhesive-bonded hybrid structures

    NASA Technical Reports Server (NTRS)

    Kirschke, L.; Prinz, R.; Schnell, H.

    1979-01-01

    Structures prepared from materials with different thermal and mechanical properties by means of fiber-strengthened binders can fail in a number of ways. The present lecture is focused on failures through debonding at the metal or at the fiber-reinforced plastic. A method for calculating the stress distribution in adhesive layers as a function of the load is outlined, and its usefulness in providing insight into the behavior of bonds in hybrid structures is noted. Means of eliminating the unfavorable effects of temperature, humidity, creep and relaxation on the bonds in the manufacture of hybrid structures are examined, along with test methods developed for such structures.

  4. Tissue adhesives: new perspectives in corneal perforations.

    PubMed

    Hirst, L W; Stark, W J; Jensen, A D

    1979-03-01

    In corneal perforations associated with extensive progressive corneal disease, a technique using tissue adhesive closure of the perforation site and reformation of the anterior chamber before penetrating keratoplasty or conjunctival flap mobilization has been described. Over the past year, six eyes have been successfully treated in this manner. This method allows reformation of the eye under local anesthesia as an emergency procedure without incarceration or injury of the intraocular contents and without pain to the patient. The definitive surgical procedure can then be performed safely under retrobulbar anesthesia.

  5. Obstetric epidurals and chronic adhesive arachnoiditis.

    PubMed

    Rice, I; Wee, M Y K; Thomson, K

    2004-01-01

    It has been suggested that obstetric epidurals lead to chronic adhesive arachnoiditis (CAA). CAA is a nebulous disease entity with much confusion over its symptomatology. This review outlines the pathological, clinical, and radiological features of the disease. The proposed diagnostic criteria for CAA are: back pain that increases on exertion, with or without leg pain; neurological abnormality on examination; and characteristic MRI findings. Using these criteria, there is evidence to show that epidural or subarachnoid placement of some contrast media, preservatives and possibly vasoconstrictors, may lead to CAA. No evidence was found that the preservative-free, low concentration bupivacaine with opioid mixtures or plain bupivacaine currently used in labour lead to CAA.

  6. Fatigue crack propagation at polymer adhesive interfaces

    SciTech Connect

    Ritter, J.E.

    1996-12-31

    Delamination of polymer adhesive interfaces often occurs due to slow crack growth under either monotonic or cyclic loading. The author`s previous research showed that moisture-assisted crack growth at epoxy/glass and epoxy acrylate/glass interfaces under monotonic loading was directly related to the applied energy release rate and relative humidity and that cyclic loading could enhance crack growth. The purpose of the present research is to compare crack growth along epoxy acrylate/glass and epoxy/PMMA interfaces under monotonic and cyclic loading.

  7. Purification of adhesive proteins from mussels.

    PubMed

    Pardo, J; Gutierrez, E; Sáez, C; Brito, M; Burzio, L O

    1990-11-01

    The adhesive polyphenolic proteins from the mussels Mytilus chilensis and Choromytilus chorus have been purified based on their solubility in dilute perchloric acid and on differential precipitation with acetone containing about 0.3 N HCl. The specific activity of the proteins obtained was 0.16 mg of 3,4-dihydroxyphenylalanine per milligram of protein, or higher. The proteins have an apparent molecular weight of about 100,000 and they contain a high proportion of 3,4-dihydroxyphenylalanine, lysine, and proline.

  8. Thin film adhesion by nanoindentation-induced superlayers. Final report

    SciTech Connect

    Gerberich, William W.; Volinsky, A.A.

    2001-06-01

    This work has analyzed the key variables of indentation tip radius, contact radius, delamination radius, residual stress and superlayer/film/interlayer properties on nanoindentation measurements of adhesion. The goal to connect practical works of adhesion for very thin films to true works of adhesion has been achieved. A review of this work titled ''Interfacial toughness measurements of thin metal films,'' which has been submitted to Acta Materialia, is included.

  9. Special adhesion of natural honeycomb walls and their application.

    PubMed

    Guo, Tianqi; Li, Muchen; Heng, Liping; Jiang, Lei

    2015-03-07

    In this paper, we investigated the wettability and adhesive behavior of the natural honeycomb wall for water and honey droplets. The cell walls have hydrophobic and highly adhesive properties for both water and honey in air. This highly adhesive cell wall was used as a "mechanical hand" to transfer micro-droplets. These findings will help us to comprehensively understand the surface properties of honeycomb walls, and will provide a novel strategy for achieving functional biomimetics based on honeycombs.

  10. Durability and Intelligent Nondestructive Evaluation of Adhesive Composite Joints

    DTIC Science & Technology

    2007-11-02

    theories used for 195 data reduction, and whether they have to be modified to model the adhesive system properly. Computer modeling of the adhesive joint...analysis of single lap joints with unidirectional and cross-ply adherends 26 2. Modeling of single lap joints with unidirectional and cross-ply...part of the research were to develop a nonlinear finite element model for a cracked single-lap adhesive joint with laminated composite adherends and

  11. Cell substratum adhesion during early development of Dictyostelium discoideum.

    PubMed

    Tarantola, Marco; Bae, Albert; Fuller, Danny; Bodenschatz, Eberhard; Rappel, Wouter-Jan; Loomis, William F

    2014-01-01

    Vegetative and developed amoebae of Dictyostelium discoideum gain traction and move rapidly on a wide range of substrata without forming focal adhesions. We used two independent assays to quantify cell-substrate adhesion in mutants and in wild-type cells as a function of development. Using a microfluidic device that generates a range of hydrodynamic shear stress, we found that substratum adhesion decreases at least 10 fold during the first 6 hr of development of wild type cells. This result was confirmed using a single-cell assay in which cells were attached to the cantilever of an atomic force probe and allowed to adhere to untreated glass surfaces before being retracted. Both of these assays showed that the decrease in substratum adhesion was dependent on the cAMP receptor CAR1 which triggers development. Vegetative cells missing talin as the result of a mutation in talA exhibited slightly reduced adhesive properties compared to vegetative wild-type cells. In sharp contrast to wild-type cells, however, these talA mutant cells did not show further reduction of adhesion during development such that after 5 hr of development they were significantly more adhesive than developed wild type cells. In addition, both assays showed that substrate adhesion was reduced in 0 hr cells when the actin cytoskeleton was disrupted by latrunculin. Consistent with previous observations, substrate adhesion was also reduced in 0 hr cells lacking the membrane proteins SadA or SibA as the result of mutations in sadA or sibA. However, there was no difference in the adhesion properties between wild type AX3 cells and these mutant cells after 6 hr of development, suggesting that neither SibA nor SadA play an essential role in substratum adhesion during aggregation. Our results provide a quantitative framework for further studies of cell substratum adhesion in Dictyostelium.

  12. Doxycycline-encapsulated nanotube-modified dentin adhesives.

    PubMed

    Feitosa, S A; Palasuk, J; Kamocki, K; Geraldeli, S; Gregory, R L; Platt, J A; Windsor, L J; Bottino, M C

    2014-12-01

    This article presents details of fabrication, biological activity (i.e., anti-matrix metalloproteinase [anti-MMP] inhibition), cytocompatibility, and bonding characteristics to dentin of a unique doxycycline (DOX)-encapsulated halloysite nanotube (HNT)-modified adhesive. We tested the hypothesis that the release of DOX from the DOX-encapsulated nanotube-modified adhesive can effectively inhibit MMP activity. We incorporated nanotubes, encapsulated or not with DOX, into the adhesive resin of a commercially available bonding system (Scotchbond Multi-Purpose [SBMP]). The following groups were tested: unmodified SBMP (control), SBMP with nanotubes (HNT), and DOX-encapsulated nanotube-modified adhesive (HNT+DOX). Changes in degree of conversion (DC) and microtensile bond strength were evaluated. Cytotoxicity was examined on human dental pulp stem cells (hDPSCs). To prove the successful encapsulation of DOX within the adhesives-but, more important, to support the hypothesis that the HNT+DOX adhesive would release DOX at subantimicrobial levels-we tested the antimicrobial activity of synthesized adhesives and the DOX-containing eluates against Streptococcus mutans through agar diffusion assays. Anti-MMP properties were assessed via β-casein cleavage assays. Increasing curing times (10, 20, 40 sec) led to increased DC values. There were no statistically significant differences (p > .05) in DC within each increasing curing time between the modified adhesives compared to SBMP. No statistically significant differences in microtensile bond strength were noted. None of the adhesives eluates were cytotoxic to the human dental pulp stem cells. A significant growth inhibition of S. mutans by direct contact illustrates successful encapsulation of DOX into the experimental adhesive. More important, DOX-containing eluates promoted inhibition of MMP-1 activity when compared to the control. Collectively, our findings provide a solid background for further testing of encapsulated MMP

  13. [Role of "leukocyte adhesion molecules" in early periodontal disease].

    PubMed

    Vierucci, S

    1992-01-01

    The purpose of this paper is to focus on functional characteristics of leukocyte adhesion molecules, on their localization and specific ligands. In fact, leukocyte chemotaxis and adhesion to endothelium is an essential step in promoting adequate immune response to bacterial infections. Since periodontal health is highly dependent on neutrophil function against the microbial dental plaque, defects in chemotaxis and adhesion of leukocytes to endothelium often result in severe, early onset periodontitis. Furthermore, oral lesions may be the only clinical manifestation of neutrophil impairment.

  14. Evaluation of high temperature structural adhesives for extended service

    NASA Technical Reports Server (NTRS)

    Hill, S. G.; Peters, P. D.; Hendricks, C. L.

    1981-01-01

    The long term thermal aging data initiated in Phase 1 is reported. All candidate adhesive systems have exhibited significant degradation in bond properties after 505K (450 F) 10,000 hour exposure. Failures appear to be adhesive in the oxide layer. Phase 2 chemical characterization, cure cycle studies, baseline data, preliminary specifications, and environmental exposure data generated on polyphenyquinoxaline is presented. Similar but limited data on LARC-13 and NR056X adhesives is reported.

  15. Laboratory Investigation on Adhesives for Naval Facilities Construction.

    DTIC Science & Technology

    1984-05-01

    when the liquid resolidifies, the bond is formed. 4. One-component, solvent-free liquids: cyanoacrylates , such as "Super Glue " anaerobics used for...urethanes) are generally stronger than solvent-based or hot-melt adhesives, which are much stronger than most aqueous-based adhesives (casein, fish, glue ...hide glue ). , . -. Iif LibraryCard Naval Civil Engineering Laboratory I LABORATORY INVESTIGATION ON ADHESIVES FOR NAVAL FACILITIES CONSTRUCTION (Final

  16. Locomotion of fish epidermal keratocytes on spatially selective adhesion patterns.

    PubMed

    Csucs, Gabor; Quirin, Katharina; Danuser, Gaudenz

    2007-11-01

    Cell migration results from forces generated by assembly, contraction, and adhesion of the cytoskeleton. To address how these forces integrate in space and time, novel assays are required that allow spatial separation of the different force categories. We used micro-contact printing of fibronectin on glass substrates to study the effect of adhesion patterns on fish epidermal keratocytes locomotion. Cells migrated at similar speeds on homogeneously adhesive substrates and on patterns with 5 microm-wide adhesive stripes interleaved by non-adhesive stripes with a width varied between 5 and 13 microm. The leading edge protruded on adhesive stripes and lagged behind on non-adhesive stripes. On patterns with non-adhesive stripes wider than 13 microm cells halted, although the lamellipodium did not collapse. High correlation was found between the widths of protruding and lagging edge segments and the widths of the underlying stripes. We explain our data by the force balances between actin polymerization, contraction and adhesion on fibronectin stripes; and between actin polymerization, contraction and lamellipodium-internal elastic tension on non-adhesive stripes. We tested our model further by blocking lamellipodium actin network contraction and polymerization. In both experiments we observed that cells eventually lost their ability to move. However, the two perturbations induced distinct morphological responses. The data suggested that forces powering forward motion of keratocytes are largely associated with network assembly whereas contraction maintains cell polarity. This study establishes spatially selective adhesion substrates and cell morphological readouts as a means to elucidate the mechanical balance between substrate adhesion and cytoskeleton-internal tension in cell migration.

  17. The peel test in experimental adhesive fracture mechanics

    NASA Technical Reports Server (NTRS)

    Anderson, G. P.; Devries, K. L.; Williams, M. L.

    1974-01-01

    Several testing methods have been proposed for obtaining critical energy release rate or adhesive fracture energy in bond systems. These tests include blister, cone, lap shear, and peel tests. Peel tests have been used for many years to compare relative strengths of different adhesives, different surface preparation techniques, etc. The present work demonstrates the potential use of the peel test for obtaining adhesive fracture energy values.

  18. Epoxy Nanocomposites - Curing Rheokinetics, Wetting and Adhesion to Fibers

    SciTech Connect

    Ilyin, S. O.; Kotomin, S. V.; Kulichikhin, V. G.

    2010-06-02

    Epoxy nanocomposites considered as challenging polymeric matrix for advanced reinforced plastics. Nanofillers change rheokinetics of epoxy resin curing, affect wetting and adhesion to aramid and carbon fibers. In all cases extreme dependence of adhesive strength vs filler content in the binder was observed. New experimental techniques were developed to study wettability and fiber-matrix adhesion interaction, using yarn penetration path length, aramid fiber knot pull-up test and electrical admittance of the fracture surface of CFRP.

  19. Epoxy Nanocomposites—Curing Rheokinetics, Wetting and Adhesion to Fibers

    NASA Astrophysics Data System (ADS)

    Ilyin, S. O.; Kotomin, S. V.; Kulichikhin, V. G.

    2010-06-01

    Epoxy nanocomposites considered as challenging polymeric matrix for advanced reinforced plastics. Nanofillers change rheokinetics of epoxy resin curing, affect wetting and adhesion to aramid and carbon fibers. In all cases extreme dependence of adhesive strength vs filler content in the binder was observed. New experimental techniques were developed to study wettability and fiber-matrix adhesion interaction, using yarn penetration path length, aramid fiber knot pull-up test and electrical admittance of the fracture surface of CFRP.

  20. Mean-field descriptions of collective migration with strong adhesion.

    PubMed

    Johnston, Stuart T; Simpson, Matthew J; Baker, Ruth E

    2012-05-01

    Random walk models based on an exclusion process with contact effects are often used to represent collective migration where individual agents are affected by agent-to-agent adhesion. Traditional mean-field representations of these processes take the form of a nonlinear diffusion equation which, for strong adhesion, does not predict the averaged discrete behavior. We propose an alternative suite of mean-field representations, showing that collective migration with strong adhesion can be accurately represented using a moment closure approach.

  1. Analysis of Adhesively Bonded Ceramics Using an Asymmetric Wedge Test

    DTIC Science & Technology

    2008-12-01

    Kern, M.; Wegner, S. M. Bonding to Zirconia Ceramic: Adhesion Methods and Their Durability. Dental Materials 1998, 14 (1), 64. 18. Newman, S. M...moisture durability of adhesive bonding of ceramics is dental applications (12–14). The adhesive bonding of ceramic orthodontic inserts presents unique...removal and repair (15, 18). Determining fracture mechanics–based strain energy release rates across the interface of dental bonds has been

  2. Functionalization of CoCr surfaces with cell adhesive peptides to promote HUVECs adhesion and proliferation

    NASA Astrophysics Data System (ADS)

    Castellanos, Maria Isabel; Mas-Moruno, Carlos; Grau, Anna; Serra-Picamal, Xavier; Trepat, Xavier; Albericio, Fernando; Joner, Michael; Gil, Francisco Javier; Ginebra, Maria Pau; Manero, Jose María; Pegueroles, Marta

    2017-01-01

    Biomimetic surface modification with peptides that have specific cell-binding moieties is a promising approach to improve endothelialization of metal-based stents. In this study, we functionalized CoCr surfaces with RGDS, REDV, YIGSR peptides and their combinations to promote endothelial cells (ECs) adhesion and proliferation. An extensive characterization of the functionalized surfaces was performed by XPS analysis, surface charge and quartz crystal microbalance with dissipation monitoring (QCM-D), which demonstrated the successful immobilization of the peptides to the surface. Cell studies demonstrated that the covalent functionalization of CoCr surfaces with an equimolar combination of RGDS and YIGSR represents the most powerful strategy to enhance the early stages of ECs adhesion and proliferation, indicating a positive synergistic effect between the two peptide motifs. Although these peptide sequences slightly increased smooth muscle cells (SMCs) adhesion, these values were ten times lower than those observed for ECs. The combination of RGDS with the REDV sequence did not show synergistic effects in promoting the adhesion or proliferation of ECs. The strategy presented in this study holds great potential to overcome clinical limitations of current metal stents by enhancing their capacity to support surface endothelialization.

  3. Zebra mussel adhesion: structure of the byssal adhesive apparatus in the freshwater mussel, Dreissena polymorpha.

    PubMed

    Farsad, Nikrooz; Sone, Eli D

    2012-03-01

    The freshwater zebra mussel (Dreissena polymorpha) owes a large part of its success as an invasive species to its ability to attach to a wide variety of substrates. As in marine mussels, this attachment is achieved by a proteinaceous byssus, a series of threads joined at a stem that connect the mussel to adhesive plaques secreted onto the substrate. Although the zebra mussel byssus is superficially similar to marine mussels, significant structural and compositional differences suggest that further investigation of the adhesion mechanisms in this freshwater species is warranted. Here we present an ultrastructural examination of the zebra mussel byssus, with emphasis on interfaces that are critical to its adhesive function. By examining the attached plaques, we show that adhesion is mediated by a uniform electron dense layer on the underside of the plaque. This layer is only 10-20 nm thick and makes direct and continuous contact with the substrate. The plaque itself is fibrous, and curiously can exhibit either a dense or porous morphology. In zebra mussels, a graded interface between the animal and the substrate mussels is achieved by interdigitation of uniform threads with the stem, in contrast to marine mussels, where the threads themselves are non-uniform. Our observations of several novel aspects of zebra mussel byssal ultrastructure may have important implications not only for preventing biofouling by the zebra mussel, but for the development of new bioadhesives as well.

  4. Adhesive barnacle peptides exhibit a steric-driven design rule to enhance adhesion between asymmetric surfaces.

    PubMed

    Raman, Sangeetha; Malms, Lukas; Utzig, Thomas; Shrestha, Buddha Ratna; Stock, Philipp; Krishnan, Shankar; Valtiner, Markus

    2017-04-01

    Barnacles exhibit superior underwater adhesion simply through sequencing of the 21 proteinogenic amino acids, without post processing or using special amino acids. Here, we measure and discuss the molecular interaction of two distinct and recurring short peptide sequences (Bp1 and Bp2) inspired from the surface binding 19kDa protein from the barnacle attachment interface. Using self-assembled monolayer (SAMs) of known physical and chemical properties on molecularly smooth gold substrates in 5mM NaCl at pH 7.3, (1) the adsorption mechanisms of the barnacle inspired peptides are explored using quartz crystal microbalance, and (2) adhesion mediating properties are measured using the surface force apparatus. The hydrophobic Bp1 peptide with a cysteine residue adsorbs irreversibly onto Au surfaces due to thiol bond formation, while on hydrophobic CH3 SAM surface, the interactions are hydrophobic in nature. Interestingly, Bp2 that contains both hydrophobic and protonated amine units exhibits asymmetric bridging with an exceptionally high adhesion energy up to 100mJ/m(2) between mica and both gold and CH3 SAM. Surprisingly on hydrophilic surfaces such as COOH- or OH-SAMs both peptides fail to show any interactions, implying the necessity of surface charge to promote bridging. Our results provide insights into the molecular aspects of manipulating and utilizing barnacle-mediated peptides to promote or inhibit underwater adhesion.

  5. The right motifs for plant cell adhesion: what makes an adhesive site?

    PubMed

    Langhans, Markus; Weber, Wadim; Babel, Laura; Grunewald, Miriam; Meckel, Tobias

    2017-01-01

    Cells of multicellular organisms are surrounded by and attached to a matrix of fibrous polysaccharides and proteins known as the extracellular matrix. This fibrous network not only serves as a structural support to cells and tissues but also plays an integral part in the process as important as proliferation, differentiation, or defense. While at first sight, the extracellular matrices of plant and animals do not have much in common, a closer look reveals remarkable similarities. In particular, the proteins involved in the adhesion of the cell to the extracellular matrix share many functional properties. At the sequence level, however, a surprising lack of homology is found between adhesion-related proteins of plants and animals. Both protein machineries only reveal similarities between small subdomains and motifs, which further underlines their functional relationship. In this review, we provide an overview on the similarities between motifs in proteins known to be located at the plant cell wall-plasma membrane-cytoskeleton interface to proteins of the animal adhesome. We also show that by comparing the proteome of both adhesion machineries at the level of motifs, we are also able to identify potentially new candidate proteins that functionally contribute to the adhesion of the plant plasma membrane to the cell wall.

  6. Measuring of the hardly measurable: adhesion properties of anti-adhesive surfaces

    NASA Astrophysics Data System (ADS)

    Purtov, Julia; Gorb, Elena V.; Steinhart, Martin; Gorb, Stanislav N.

    2013-04-01

    Adhesion is a universal phenomenon influencing many processes in natural and technical systems. To elucidate these influences, reliable measurements of adhesion forces are of high importance. In the present study, by using a microforce tester combined with a compliant sticky probe, we introduce a newly established method allowing adhesion measurements on surfaces with low adhesive capabilities. Four quality control tests revealed a high reproducibility and reliability of data obtained. Further advantages of the method are (1) defined geometry of the probe, (2) ease attachment of the probe to the cantilever, (3) its applicability for time consuming experiments, (4) as well as a low price of components and a minimum of required equipment. We present the first results obtained by using this method in a case study with six epoxy resin replicas having various roughness ( R a =0.007-3.515 μm). Interestingly, the highest pull-off force values were obtained not on the smooth sample, but on the surface with the finest microroughness ( R a =0.150 μm). With a further increase in the surface microroughness, pull-off forces continuously decreased. These results are in accordance with previously reported theoretical predictions.

  7. Cell adhesion: integrating cytoskeletal dynamics and cellular tension

    PubMed Central

    Parsons, J. Thomas; Horwitz, Alan Rick; Schwartz, Martin A.

    2010-01-01

    Cell migration affects all morphogenetic processes and contributes to numerous diseases, including cancer and cardiovascular disease. For most cells in most environments, movement begins with protrusion of the cell membrane followed by the formation of new adhesions at the cell front that link the actin cytoskeleton to the substratum, generation of traction forces that move the cell forwards and disassembly of adhesions at the cell rear. Adhesion formation and disassembly drive the migration cycle by activating Rho GTPases, which in turn regulate actin polymerization and myosin II activity, and therefore adhesion dynamics. PMID:20729930

  8. Cell Adhesion in Epidermal Development and Barrier Formation

    PubMed Central

    Sumigray, Kaelyn D.; Lechler, Terry

    2015-01-01

    Cell–cell adhesions are necessary for structural integrity and barrier formation of the epidermis. Here, we discuss insights from genetic and cell biological studies into the roles of individual cell–cell junctions and their composite proteins in regulating epidermal development and function. In addition to individual adhesive functions, we will discuss emerging ideas on mechanosensation/transduction of junctions in the epidermis, noncanonical roles for adhesion proteins, and crosstalk/interdependencies between the junctional systems. These studies have revealed that cell adhesion proteins are connected to many aspects of tissue physiology including growth control, differentiation, and inflammation. PMID:25733147

  9. Ultrafast UV-Curable Adhesives for Optical Pick-Ups

    NASA Astrophysics Data System (ADS)

    Chung, Chang-Kyu; Jang, Kyung-Woon; Choi, Hyoung Gil; Jang, Jiyoung; Moon, Youngjun; Jeon, Chulho

    2013-08-01

    This paper describes novel ultraviolet (UV)-curable adhesives with an ultrafast curing rate which are fully cured within 8 s for optical pick-up (OPU) applications. Two kinds of oligomers (novolac epoxy acrylate and urethane acrylate), additives, and inorganic fillers were prepared for the formulation of the adhesives. In addition, three kinds of photo-initiator [2,2-dimethoxy-2-phenylacetophenone and 2-hydroxy-2-methylpropiophenone for surface curing and (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide (TMDPO) for deep curing] were mixed to increase the curing rate. Photo-differential scanning calorimetry (photo-DSC) analyses showed that the newly formulated UV adhesives had faster curing rate than conventional UV adhesives. The UV adhesives were applied to OPUs for DVD/CD-RW, and five kinds of reliability tests, i.e., thermal shock, low-temperature storage, high-temperature storage, high temperature/high humidity, and nonoperation shock tests, were conducted to evaluate the adhesive reliability. According to the results of reliability tests and thermal stress simulations, the UV adhesives with lower storage modulus ( E') showed better thermal shock reliability due to lower thermal stresses. In addition, OPUs assembled using the UV adhesives passed all reliability tests. Consequently, the UV adhesives were successfully applied to OPUs in OPU production lines, contributing to mass production.

  10. Electrochromic switchable mirror glass fabricated using adhesive electrolyte layer

    NASA Astrophysics Data System (ADS)

    Tajima, Kazuki; Hotta, Hiromi; Yamada, Yasusei; Okada, Masahisa; Yoshimura, Kazuki

    2012-12-01

    We have developed a simple process for fabricating electrochromic switchable mirror glass using an adhesive electrolyte layer. The adhesive electrolyte layer was a mixture of polyethyleneimine electrolyte and polyvinyl butyral adhesive dissolved in gamma-butyrolactone. The device was formed from two substrates; the adhesive electrolyte layer was applied to one of the substrates before they were stuck together. The applied voltage required to change the state of the device was smaller than that of a conventional device with a solid electrolyte layer deposited by sputtering. Our method is simple, fast, and efficient and can be used to fabricate large devices.

  11. Bond Assembly FOD Zones - A Procedure for Assuring Acceptable Adhesion

    NASA Technical Reports Server (NTRS)

    Evans, Kurt; Wurth, Laura; Mitchell, Mark

    2009-01-01

    Rocket motor components are primarily assembled by adhesion. a) For example, the RSRM (Reusable Solid Rocket Motor - part of the Space Shuttle Boosters) system contains 10,000 sq ft of bondline area. b) Rocket motors contain a variety of adhesive/substrate bond systems c) Bond system performance requirements also vary. To assemble reliable components, ATK Space Systems and customers invest substantial resources to the study of bond assembly processes. a) Surface and adhesion science; b) Adhesive chemistry; c) Process parameters; d) Contamination effects.

  12. Adhesion of Actinobacillus actinomycetemcomitans to a human oral cell line.

    PubMed Central

    Mintz, K P; Fives-Taylor, P M

    1994-01-01

    Two quantitative, rapid assays were developed to study the adhesion of Actinobacillus actinomycetemcomitans, an oral bacterium associated with periodontal disease, to human epithelial cells. The human oral carcinoma cell line KB was grown in microtiter plates, and adherent bacteria were detected by an enzyme-linked immunosorbent assay with purified anti-A. actinomycetemcomitans serum and horseradish peroxidase-conjugated secondary antibody or [3H]thymidine-labeled bacteria. Adhesion was found to be time dependent and increased linearly with increasing numbers of bacteria added. Variation in the level of adhesion was noted among strains of A. actinomycetemcomitans. Adhesion was not significantly altered by changes in pH (from pH 5 to 9) but was sensitive to sodium chloride concentrations greater than 0.15 M. Pooled human saliva was inhibitory for adhesion when bacteria were pretreated with saliva before being added to the cells. Pretreatment of the KB cells with saliva did not inhibit adhesion. Protease treatment of A. actinomycetemcomitans reduced adhesion of the bacteria to KB cells. The data are consistent with the hypothesis that a protein(s) is required for bacterial adhesion and that host components may play a role in modulating adhesion to epithelial cells. Images PMID:8063383

  13. Mixed Extracellular Matrix Ligands Synergistically Modulate Integrin Adhesion and Signaling

    PubMed Central

    Reyes, Catherine D.; Petrie, Timothy A.; García, Andrés J

    2008-01-01

    Cell adhesion to extracellular matrix (ECM) components through cell-surface integrin receptors is essential to the formation, maintenance and repair of numerous tissues, and therefore represents a central theme in the design of bioactive materials that successfully interface with the body. While the adhesive responses associated with a single ligand have been extensively analyzed, the effects of multiple integrin subtypes binding to multivalent ECM signals remain poorly understood. In the present study, we generated a high throughput platform of non-adhesive surfaces presenting well-defined, independent densities of two integrin-specific engineered ligands for the type I collagen (COL-I) receptor α2β1 and the fibronectin (FN) receptor α5β1 to evaluate the effects of integrin cross-talk on adhesive responses. Engineered surfaces displayed ligand density-dependent adhesive effects, and mixed ligand surfaces significantly enhanced cell adhesion strength and focal adhesion assembly compared to single FN and COL-I ligand surfaces. Moreover, surfaces presenting mixed COL-I/FN ligands synergistically enhanced FAK activation compared to the single ligand substrates. The enhanced adhesive activities of the mixed ligand surfaces also promoted elevated proliferation rates. Our results demonstrate interplay between multivalent ECM ligands in adhesive responses and downstream cellular signaling. PMID:18613064

  14. Stress analysis of adhesive bonded stiffener plates and double joints

    NASA Technical Reports Server (NTRS)

    Yuceoglu, U.; Updike, D. P.

    1975-01-01

    The general problem of adhesive bonded stiffener plates and double joints of dissimilar orthotropic adherends with transverse shear deformations are analyzed. Adhesive layers are assumed to be of an isotropic, elastic and relatively flexible material. It is shown that the stress distributions in the adhesive layers are very much dependent on the bending deformations in adherends. Also, it is found that, in the adhesive layer, maximum transverse normal stress is, in many cases, larger than the longitudinal shear stress and that both occur at the edge of the joint. The general method of solution developed is applied to several practical examples.

  15. Postsurgical intrapericardial adhesions: mechanisms of formation and prevention.

    PubMed

    Cannata, Aldo; Petrella, Duccio; Russo, Claudio Francesco; Bruschi, Giuseppe; Fratto, Pasquale; Gambacorta, Marcello; Martinelli, Luigi

    2013-05-01

    Postsurgical intrapericardial adhesions are still considered an unavoidable consequence of cardiothoracic operations. They increase the technical difficulty and the risk of reoperations. The pathogenesis of postsurgical adhesions is a multistep process, and the main key players are (1) loss of mesothelial cells, (2) accumulation of fibrin in areas devoid of mesothelial cells, (3) loss of normal pericardial fibrinolysis, and (4) local inflammation. Today, very promising methods to reduce adhesions are available for clinical use. This report reviews the process of formation of adhesions and the methods to prevent them, classified according to the mechanism of action.

  16. Role of cellular adhesions in tissue dynamics spectroscopy

    NASA Astrophysics Data System (ADS)

    Merrill, Daniel A.; An, Ran; Turek, John; Nolte, David

    2014-02-01

    Cellular adhesions play a critical role in cell behavior, and modified expression of cellular adhesion compounds has been linked to various cancers. We tested the role of cellular adhesions in drug response by studying three cellular culture models: three-dimensional tumor spheroids with well-developed cellular adhesions and extracellular matrix (ECM), dense three-dimensional cell pellets with moderate numbers of adhesions, and dilute three-dimensional cell suspensions in agarose having few adhesions. Our technique for measuring the drug response for the spheroids and cell pellets was biodynamic imaging (BDI), and for the suspensions was quasi-elastic light scattering (QELS). We tested several cytoskeletal chemotherapeutic drugs (nocodazole, cytochalasin-D, paclitaxel, and colchicine) on three cancer cell lines chosen from human colorectal adenocarcinoma (HT-29), human pancreatic carcinoma (MIA PaCa-2), and rat osteosarcoma (UMR-106) to exhibit differences in adhesion strength. Comparing tumor spheroid behavior to that of cell suspensions showed shifts in the spectral motion of the cancer tissues that match predictions based on different degrees of cell-cell contacts. The HT-29 cell line, which has the strongest adhesions in the spheroid model, exhibits anomalous behavior in some cases. These results highlight the importance of using three-dimensional tissue models in drug screening with cellular adhesions being a contributory factor in phenotypic differences between the drug responses of tissue and cells.

  17. Using Adhesive Patterning to Construct 3D Paper Microfluidic Devices.

    PubMed

    Kalish, Brent; Tsutsui, Hideaki

    2016-04-01

    We demonstrate the use of patterned aerosol adhesives to construct both planar and nonplanar 3D paper microfluidic devices. By spraying an aerosol adhesive through a metal stencil, the overall amount of adhesive used in assembling paper microfluidic devices can be significantly reduced. We show on a simple 4-layer planar paper microfluidic device that the optimal adhesive application technique and device construction style depends heavily on desired performance characteristics. By moderately increasing the overall area of a device, it is possible to dramatically decrease the wicking time and increase device success rates while also reducing the amount of adhesive required to keep the device together. Such adhesive application also causes the adhesive to form semi-permanent bonds instead of permanent bonds between paper layers, enabling single-use devices to be non-destructively disassembled after use. Nonplanar 3D origami devices also benefit from the semi-permanent bonds during folding, as it reduces the likelihood that unrelated faces may accidently stick together. Like planar devices, nonplanar structures see reduced wicking times with patterned adhesive application vs uniformly applied adhesive.

  18. Self-assembled Nano-layering at the Adhesive interface.

    PubMed

    Yoshida, Y; Yoshihara, K; Nagaoka, N; Hayakawa, S; Torii, Y; Ogawa, T; Osaka, A; Meerbeek, B Van

    2012-04-01

    According to the 'Adhesion-Decalcification' concept, specific functional monomers within dental adhesives can ionically interact with hydroxyapatite (HAp). Such ionic bonding has been demonstrated for 10-methacryloyloxydecyl dihydrogen phosphate (MDP) to manifest in the form of self-assembled 'nano-layering'. However, it remained to be explored if such nano-layering also occurs on tooth tissue when commercial MDP-containing adhesives (Clearfil SE Bond, Kuraray; Scotchbond Universal, 3M ESPE) were applied following common clinical application protocols. We therefore characterized adhesive-dentin interfaces chemically, using x-ray diffraction (XRD) and energy-dispersive x-ray spectroscopy (EDS), and ultrastructurally, using (scanning) transmission electron microscopy (TEM/STEM). Both adhesives revealed nano-layering at the adhesive interface, not only within the hybrid layer but also, particularly for Clearfil SE Bond (Kuraray), extending into the adhesive layer. Since such self-assembled nano-layering of two 10-MDP molecules, joined by stable MDP-Ca salt formation, must make the adhesive interface more resistant to biodegradation, it may well explain the documented favorable clinical longevity of bonds produced by 10-MDP-based adhesives.

  19. Bacterial adhesion capacity on food service contact surfaces.

    PubMed

    Fink, Rok; Okanovič, Denis; Dražič, Goran; Abram, Anže; Oder, Martina; Jevšnik, Mojca; Bohinc, Klemen

    2017-03-28

    The aim of this study was to analyse the adhesion of E. coli, P. aeruginosa and S. aureus on food contact materials, such as polyethylene terephthalate, silicone, aluminium, Teflon and glass. Surface roughness, streaming potential and contact angle were measured. Bacterial properties by contact angle and specific charge density were characterised. The bacterial adhesion analysis using staining method and scanning electron microscopy showed the lowest adhesion on smooth aluminium and hydrophobic Teflon for most of the bacteria. However, our study indicates that hydrophobic bacteria with high specific charge density attach to those surfaces more intensively. In food services, safety could be increased by selecting material with low adhesion to prevent cross contamination.

  20. Addition polyimide adhesives containing ATBN and silicone elastomers

    NASA Technical Reports Server (NTRS)

    Saint Clair, A. K.; Saint Clair, T. L.

    1981-01-01

    A study was conducted to determine the effects of added elastomers on the thermal stability, adhesive strength, and fracture toughness of LARC-13, a high-temperature addition polyimide adhesive. Various butadiene/acrylonitrile and silicon elastomers were incorporated into the polyimide resin either as physical polyblends, or by chemically reacting the elastomers with the polyimide backbone. Adhesive single lap-shear and T-peel strengths were measured before and after ageing at elevated temperature. A tapered double-cantilever beam specimen was used to determine the fracture toughness of the elastomer-modified polyimide adhesives.