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Sample records for adhesive applying uniform

  1. Uniform insulation applied-B ion diode

    DOEpatents

    Seidel, David B.; Slutz, Stephen A.

    1988-01-01

    An applied-B field extraction ion diode has uniform insulation over an anode surface for increased efficiency. When the uniform insulation is accomplished with anode coils, and a charge-exchange foil is properly placed, the ions may be focused at a point on the z axis.

  2. Electrostatic adhesion of multiple non-uniformly charged dielectric particles

    NASA Astrophysics Data System (ADS)

    Kemp, B. A.; Whitney, J. G.

    2013-01-01

    Charged particle adhesion measurements can be as much as one order of magnitude higher than theoretical calculations. This discrepancy has ignited a debate as to the nature of the physics occurring with microscopic particle adhesion. Attempts to bring calculations closer to measured results have produced models that include multiple particle interactions, dielectric polarization, and non-uniform charge. Individually, each of these models can only produce a 2× to 5× enhancement in predicted adhesion force over simple Coulombic attraction. In this correspondence, an analytical model of electrostatic particle forces is developed, which allows for independent assignment of dielectric constant and non-uniform surface charge distribution to an arbitrary number of particles. Because the model can include an image plane, it is ideal for electrostatic adhesion calculations. Application to a monolayer of printed toner particles predicts nearly an order of magnitude increase in adhesion force over Coulombic attraction. These results are the first analytical results to place predictions of charged particle adhesion on the same order of magnitude with measurements.

  3. Highly Anisotropic Adhesive Film Made from Upside-Down, Flat, and Uniform Vertically Aligned CNTs.

    PubMed

    Hong, Sanghyun; Lundstrom, Troy; Ghosh, Ranajay; Abdi, Hamed; Hao, Ji; Jeoung, Sun Kyoung; Su, Paul; Suhr, Jonghwan; Vaziri, Ashkan; Jalili, Nader; Jung, Yung Joon

    2016-12-14

    We have created a multifunctional dry adhesive film with transferred vertically aligned carbon nanotubes (VA-CNTs). This unique VA-CNT film was fabricated by a multistep transfer process, converting the flat and uniform bottom of VA-CNTs grown on atomically flat silicon wafer substrates into the top surface of an adhesive layer. Unlike as-grown VA-CNTs, which have a nonuniform surface, randomly entangled CNT arrays, and a weak interface between the CNTs and substrates, this transferred VA-CNT film shows an extremely high coefficient of static friction (COF) of up to 60 and a shear adhesion force 30 times higher (12 N/cm(2)) than that of the as-grown VA-CNTs under a very small preloading of 0.2 N/cm(2). Moreover, a near-zero normal adhesion force was observed with 20 mN/cm(2) preloading and a maximum 100-μm displacement in a piezo scanner, demonstrating ideal properties for an artificial gecko foot. Using this unique structural feature and anisotropic adhesion properties, we also demonstrate effective removal and assembly of nanoparticles into organized micrometer-scale circular and line patterns by a single brushing of this flat and uniform VA-CNT film.

  4. 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.

  5. 20 CFR 641.800 - What uniform administrative requirements apply to the use of SCSEP funds?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false What uniform administrative requirements apply to the use of SCSEP funds? 641.800 Section 641.800 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR PROVISIONS GOVERNING THE SENIOR COMMUNITY SERVICE EMPLOYMENT...

  6. 20 CFR 641.800 - What uniform administrative requirements apply to the use of SCSEP funds?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 3 2012-04-01 2012-04-01 false What uniform administrative requirements apply to the use of SCSEP funds? 641.800 Section 641.800 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR PROVISIONS GOVERNING THE SENIOR COMMUNITY SERVICE EMPLOYMENT...

  7. 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 ...

  8. 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 ...

  9. Adhesion of voids to bimetal interfaces with non-uniform energies.

    PubMed

    Zheng, Shijian; Shao, Shuai; Zhang, Jian; Wang, Yongqiang; Demkowicz, Michael J; Beyerlein, Irene J; Mara, Nathan A

    2015-10-21

    Interface engineering has become an important strategy for designing radiation-resistant materials. Critical to its success is fundamental understanding of the interactions between interfaces and radiation-induced defects, such as voids. Using transmission electron microscopy, here we report an interesting phenomenon in their interaction, wherein voids adhere to only one side of the bimetal interfaces rather than overlapping them. We show that this asymmetrical void-interface interaction is a consequence of differing surface energies of the two metals and non-uniformity in their interface formation energy. Specifically, voids grow within the phase of lower surface energy and wet only the high-interface energy regions. Furthermore, because this outcome cannot be accounted for by wetting of interfaces with uniform internal energy, our report provides experimental evidence that bimetal interfaces contain non-uniform internal energy distributions. This work also indicates that to design irradiation-resistant materials, we can avoid void-interface overlap via tuning the configurations of interfaces.

  10. Adhesion of voids to bimetal interfaces with non-uniform energies

    PubMed Central

    Zheng, Shijian; Shao, Shuai; Zhang, Jian; Wang, Yongqiang; Demkowicz, Michael J.; Beyerlein, Irene J.; Mara, Nathan A.

    2015-01-01

    Interface engineering has become an important strategy for designing radiation-resistant materials. Critical to its success is fundamental understanding of the interactions between interfaces and radiation-induced defects, such as voids. Using transmission electron microscopy, here we report an interesting phenomenon in their interaction, wherein voids adhere to only one side of the bimetal interfaces rather than overlapping them. We show that this asymmetrical void-interface interaction is a consequence of differing surface energies of the two metals and non-uniformity in their interface formation energy. Specifically, voids grow within the phase of lower surface energy and wet only the high-interface energy regions. Furthermore, because this outcome cannot be accounted for by wetting of interfaces with uniform internal energy, our report provides experimental evidence that bimetal interfaces contain non-uniform internal energy distributions. This work also indicates that to design irradiation-resistant materials, we can avoid void-interface overlap via tuning the configurations of interfaces. PMID:26486278

  11. Adhesion of voids to bimetal interfaces with non-uniform energies

    SciTech Connect

    Zheng, Shijian; Shao, Shuai; Zhang, Jian; Wang, Yongqiang; Demkowicz, Michael J.; Beyerlein, Irene J.; Mara, Nathan A.

    2015-10-21

    Interface engineering has become an important strategy for designing radiation-resistant materials. Critical to its success is fundamental understanding of the interactions between interfaces and radiation-induced defects, such as voids. Using transmission electron microscopy, here we report an interesting phenomenon in their interaction, wherein voids adhere to only one side of the bimetal interfaces rather than overlapping them. We show that this asymmetrical void-interface interaction is a consequence of differing surface energies of the two metals and non-uniformity in their interface formation energy. Specifically, voids grow within the phase of lower surface energy and wet only the high-interface energy regions. Furthermore, because this outcome cannot be accounted for by wetting of interfaces with uniform internal energy, our report provides experimental evidence that bimetal interfaces contain non-uniform internal energy distributions. Ultimately, this work also indicates that to design irradiation-resistant materials, we can avoid void-interface overlap via tuning the configurations of interfaces.

  12. Adhesion of voids to bimetal interfaces with non-uniform energies

    DOE PAGES

    Zheng, Shijian; Shao, Shuai; Zhang, Jian; ...

    2015-10-21

    Interface engineering has become an important strategy for designing radiation-resistant materials. Critical to its success is fundamental understanding of the interactions between interfaces and radiation-induced defects, such as voids. Using transmission electron microscopy, here we report an interesting phenomenon in their interaction, wherein voids adhere to only one side of the bimetal interfaces rather than overlapping them. We show that this asymmetrical void-interface interaction is a consequence of differing surface energies of the two metals and non-uniformity in their interface formation energy. Specifically, voids grow within the phase of lower surface energy and wet only the high-interface energy regions. Furthermore,more » because this outcome cannot be accounted for by wetting of interfaces with uniform internal energy, our report provides experimental evidence that bimetal interfaces contain non-uniform internal energy distributions. Ultimately, this work also indicates that to design irradiation-resistant materials, we can avoid void-interface overlap via tuning the configurations of interfaces.« less

  13. Development of a novel device for applying uniform doses of electron beam irradiation on carcasses.

    PubMed

    Maxim, Joseph E; Neal, Jack A; Castillo, Alejandro

    2014-01-01

    The Maxim's Electron Scatter Chamber (Maxim Chamber) was developed to obtain uniform dose distribution when applying electron beam (e-beam) irradiation to materials of irregular surface. This was achieved by placing a stainless steel mesh surrounding a cylindrical area where the target sample was placed. Upon contact with the mesh, electrons scatter and are directed onto the target from multiple angles, eliminating the e-beam linearity and resulting in a uniform dose distribution over the target surface. The effect of irradiation in the Maxim Chamber on dose distribution and pathogen reduction was tested on rabbit carcasses to simulate other larger carcasses. The dose uniformity ratio (DUR) on the rabbit carcasses was 1.8, indicating an acceptable dose distribution. On inoculated carcasses, this treatment reduced Escherichia coli O157:H7 by >5 log cycles. These results indicate that carcass irradiation using e-beam is feasible using the Maxim's electron scattering chamber. Appropriate adjustments will be further needed for commercial application on beef and other animal carcasses.

  14. Micro-tensile bond strength of adhesive systems applied on occlusal primary enamel.

    PubMed

    Ramires-Romito, Ana Cláudia; Reis, Alessandra; Loguercio, Alessandro Dourado; de Góes, Mario Fernando; Grande, Rosa Helena Miranda

    2004-01-01

    The aim of this study was to evaluate the micro-tensile bond strength of adhesive systems (OptiBond Solo, Kerr; Prime & Bond NT, Dentsply) on occlusal surface of primary molars. The adhesives were tested under manufacturers' specifications and after contamination of the bonding site with saliva. Hourglass cylindrical-shaped samples were obtained and subjected to a tensile force. No significant difference was observed among the groups. OptiBond Solo and Prime & Bond NT showed similar values of bond strengths when applied on occlusal enamel of primary molar under either saliva contamination or not.

  15. Comparison of Uniform and Non-uniform Water Flux Density Approaches Applied on a Mathematical Model of Heat Transfer and Solidification for a Continuous Casting of Round Billets

    NASA Astrophysics Data System (ADS)

    Assuncao, Charles Sostenes; Tavares, Roberto Parreiras; Oliveira, Guilherme; Pereira, Luiz Carlos

    2015-02-01

    In the present work, the water flux densities of nozzles with flat jet and full cone jet were experimentally measured using an apparatus in industrial scale that reproduces the secondary cooling of the continuous casting of round billets of Vallourec Tubos do Brasil. A mathematical function was defined to express the water flux density in both longitudinal and angular directions of the strand. A mathematical model for heat transfer and solidification for the continuous casting of round billets was developed applying the experimental water flux density profile, establishing a non-uniform water distribution approach. The mathematical model was validated by experimental measurements of the billet superficial temperature, performed at the industrial plant. The results of the mathematical model using both uniform and non-uniform water flux density approaches were compared. The non-uniform water distribution approach enabled to identify important variations of the heat transfer coefficients and the billet temperatures, especially in the first cooling zones where the steel temperature is higher, and to assess more accurately the local effects of the water distribution on the thermal behavior of the strand. The non-uniform water flux density approach applied to the mathematical model was a useful and more accurate tool to improve the comprehension of the thermal behavior of the steel along the secondary cooling.

  16. LONG-TERM BOND STRENGTH OF ADHESIVE SYSTEMS APPLIED TO ETCHED AND DEPROTEINIZED DENTIN

    PubMed Central

    Uceda-Gómez, Ninoshka; Loguercio, Alessandro Dourado; Moura, Sandra Kiss; Grande, Rosa Helena Miranda; Oda, Margareth; Reis, Alessandra

    2007-01-01

    The aim of this study was to evaluate the early and 12-month bond strength of two adhesive systems (Single Bond-SB and One Step-OS) applied to demineralized dentin (WH) and demineralized/NaOCl-treated dentin (H). Twenty flat dentin surfaces were exposed, etched, rinsed and slightly dried. For the H groups, a solution of 10% NaOCl was applied for 60 s, rinsed (15 s) and slightly dried. The adhesives were applied according to the manufacturer's instructions and composite resin crowns were incrementally constructed. After 24 h (water-37°C), the specimens was sectioned in order to obtain resin-dentin sticks (0.8 mm2). The specimens were tested in microtensile (0.5 mm/min) immediately (IM) or after 12 months of water storage (12M). The data (MPa) were subjected to ANOVA and Tukey's test (α=0.05). Only the main factors adhesive and time were significant (p=0.004 and p=0.003, respectively). SB (42.3±9.1) showed higher bond strengths than OS (33.6±11.6). The mean bond strength for IM-group (42.5±8.7) was statistically superior to 12M (33.3±11.8). The use of 10% NaOCl, after acid etching, did not improve the immediate and the long-term resin-dentin bond strength. PMID:19089183

  17. Applying simulation model to uniform field space charge distribution measurements by the PEA method

    SciTech Connect

    Liu, Y.; Salama, M.M.A.

    1996-12-31

    Signals measured under uniform fields by the Pulsed Electroacoustic (PEA) method have been processed by the deconvolution procedure to obtain space charge distributions since 1988. To simplify data processing, a direct method has been proposed recently in which the deconvolution is eliminated. However, the surface charge cannot be represented well by the method because the surface charge has a bandwidth being from zero to infinity. The bandwidth of the charge distribution must be much narrower than the bandwidths of the PEA system transfer function in order to apply the direct method properly. When surface charges can not be distinguished from space charge distributions, the accuracy and the resolution of the obtained space charge distributions decrease. To overcome this difficulty a simulation model is therefore proposed. This paper shows their attempts to apply the simulation model to obtain space charge distributions under plane-plane electrode configurations. Due to the page limitation for the paper, the charge distribution originated by the simulation model is compared to that obtained by the direct method with a set of simulated signals.

  18. 20 CFR 641.847 - What uniform allowable cost requirements apply to the use of SCSEP funds?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false What uniform allowable cost requirements apply to the use of SCSEP funds? 641.847 Section 641.847 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR PROVISIONS GOVERNING THE SENIOR COMMUNITY SERVICE EMPLOYMENT...

  19. 20 CFR 641.847 - What uniform allowable cost requirements apply to the use of SCSEP funds?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 3 2012-04-01 2012-04-01 false What uniform allowable cost requirements apply to the use of SCSEP funds? 641.847 Section 641.847 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR PROVISIONS GOVERNING THE SENIOR COMMUNITY SERVICE EMPLOYMENT...

  20. 20 CFR 641.847 - What uniform allowable cost requirements apply to the use of SCSEP funds?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... subrecipients must follow the uniform allowable cost requirements that apply to their type of organization. For example, a local government subrecipient receiving SCSEP funds from a nonprofit organization must use the allowable cost requirements for governmental organizations in OMB Circular A-87. The...

  1. The influence of carrier roughness on adhesion, content uniformity and the in vitro deposition of terbutaline sulphate from dry powder inhalers.

    PubMed

    Flament, Marie-Pierre; Leterme, Pierre; Gayot, Anne

    2004-05-04

    The aim of this study was to establish a correlation between carrier characteristics and the dispersibility of drug from the blend. The influence of the roughness of a commonly used carrier material, lactose monohydrate, on the adhesion, dose uniformity, and aerodynamic properties of a model drug, terbutaline sulphate was investigated. Evaluation of adhesion was carried out with a mechanical sieve and an Alpine air-jet sieve. For the characterisation of lactose roughness, we used image analysis software. Aerodynamic evaluation of fine particle dose and emitted dose was obtained using a twin stage impinger. The study with the mechanical sieve demonstrated that at least 60% of drug adheres to lactose. The Alpine air-jet sieve assays showed there was a correlation between drug separation from a carrier by sieving and that obtained from longer in vitro deposition studies. Adhesion, blend homogeneity and stability are related to the surface roughness of the lactose used as carrier. There is a linear relationship between the parameters "fine particle fraction" and "roughness". A compromise between homogeneity and drug liberation must be found: a certain roughness is necessary to allow for drug adhesion and blend homogeneity, but if too high it will prevent drug liberation after inhalation.

  2. Bicubic uniform B-spline wavefront fitting technology applied in computer-generated holograms

    NASA Astrophysics Data System (ADS)

    Cao, Hui; Sun, Jun-qiang; Chen, Guo-jie

    2006-02-01

    This paper presented a bicubic uniform B-spline wavefront fitting technology to figure out the analytical expression for object wavefront used in Computer-Generated Holograms (CGHs). In many cases, to decrease the difficulty of optical processing, off-axis CGHs rather than complex aspherical surface elements are used in modern advanced military optical systems. In order to design and fabricate off-axis CGH, we have to fit out the analytical expression for object wavefront. Zernike Polynomial is competent for fitting wavefront of centrosymmetric optical systems, but not for axisymmetrical optical systems. Although adopting high-degree polynomials fitting method would achieve higher fitting precision in all fitting nodes, the greatest shortcoming of this method is that any departure from the fitting nodes would result in great fitting error, which is so-called pulsation phenomenon. Furthermore, high-degree polynomials fitting method would increase the calculation time in coding computer-generated hologram and solving basic equation. Basing on the basis function of cubic uniform B-spline and the character mesh of bicubic uniform B-spline wavefront, bicubic uniform B-spline wavefront are described as the product of a series of matrices. Employing standard MATLAB routines, four kinds of different analytical expressions for object wavefront are fitted out by bicubic uniform B-spline as well as high-degree polynomials. Calculation results indicate that, compared with high-degree polynomials, bicubic uniform B-spline is a more competitive method to fit out the analytical expression for object wavefront used in off-axis CGH, for its higher fitting precision and C2 continuity.

  3. In vivo bracket bond strength using two adhesive systems applied under wet and dry conditions.

    PubMed

    Ciola, Elida N; Picco, Alicia M; Sois, Ana M; Lucena, Mercedes H; Alonso, Verónica; Valvo, Maela; García, Luis; Geazzi, Ariel

    2006-01-01

    The purpose of this study was to investigate, in vivo, the bond strength of two adhesive materials: a moisture insensitive primer (MIP)* and a one step self etching primer (SEP)*, both used with Transbond XT* on dry and wet enamel and an adhesion time of 10-15 minutes. First or second upper and/or lower bicuspids (n = 124), to be extracted for orthodontic reasons, were used. A comparison of the materials' behavior was conducted under four different situations: 1) MIP on enamel etched and dry; 2) MIP on a surface etched and wetted with patient's saliva; 3) SEP on a dry field, 4) SEP on a saliva-wet enamel. For statistical analysis, Dunn-Sidak's multiple comparison test was applied with a probability of less than 0.05 (before correction). Stainless steel brackets with mesh-backed pads were bonded to the teeth. Bond strength was tested with modified orthodontic pliers on which a strain-gage was fixed to measure handle deformation while debonding. Moisture insensitive primer tested on wet enamel showed the highest mean bond strength outcomes (8.98 MPa) compared to one step etching primer (5.81 MPa). Statistical difference between these groups was significant (p = 0.000). Standard deviation was lower for the one-step technique, under dry and wet conditions. Since the media bond strength of SEP proved sufficient for clinical purposes and its behavior tended to be more homogeneous, this was considered the best choice.

  4. Involvement of flocculin in negative potential-applied ITO electrode adhesion of yeast cells

    PubMed Central

    Koyama, Sumihiro; Tsubouchi, Taishi; Usui, Keiko; Uematsu, Katsuyuki; Tame, Akihiro; Nogi, Yuichi; Ohta, Yukari; Hatada, Yuji; Kato, Chiaki; Miwa, Tetsuya; Toyofuku, Takashi; Nagahama, Takehiko; Konishi, Masaaki; Nagano, Yuriko; Abe, Fumiyoshi

    2015-01-01

    The purpose of this study was to develop novel methods for attachment and cultivation of specifically positioned single yeast cells on a microelectrode surface with the application of a weak electrical potential. Saccharomyces cerevisiae diploid strains attached to an indium tin oxide/glass (ITO) electrode to which a negative potential between −0.2 and −0.4 V vs. Ag/AgCl was applied, while they did not adhere to a gallium-doped zinc oxide/glass electrode surface. The yeast cells attached to the negative potential-applied ITO electrodes showed normal cell proliferation. We found that the flocculin FLO10 gene-disrupted diploid BY4743 mutant strain (flo10Δ /flo10Δ) almost completely lost the ability to adhere to the negative potential-applied ITO electrode. Our results indicate that the mechanisms of diploid BY4743 S. cerevisiae adhesion involve interaction between the negative potential-applied ITO electrode and the Flo10 protein on the cell wall surface. A combination of micropatterning techniques of living single yeast cell on the ITO electrode and omics technologies holds potential of novel, highly parallelized, microchip-based single-cell analysis that will contribute to new screening concepts and applications. PMID:26187908

  5. 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.

  6. 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

  7. Transdentinal cytotoxicity of experimental adhesive systems of different hydrophilicity applied to ethanol-saturated dentin

    PubMed Central

    Bianchi, Luciana; Ribeiro, Ana Paula Dias; de Oliveira Carrilho, Marcela Rocha; Pashley, David H.; de Souza Costa, Carlos Alberto; Hebling, Josimeri

    2014-01-01

    The aim of this study was to evaluate the transdentinal cytotoxicity of experimental adhesive systems (EASs) with different hydrophilicity and dentin saturation solutions (ethanol and water) on odontoblast-like cells. One hundred 0.4-mm-thick dentin discs were mounted in in vitro pulp chambers and assigned to 10 groups. Odontoblast-like cells MDPC-23 were seeded onto the pulpal side of the discs, incubated for 48h. The EASs with increasing hydrophilicity (R2, R3, R4 and R5) were applied to the occlusal side of the discs after acid etching and saturation of demineralized dentin with water or ethanol. R0 (water and ethanol- no adhesive) served as controls. After 24h, cell metabolism was evaluated by SDH enzyme production (MTT assay; n=8 discs) and cell morphology was examined by SEM (n=2 discs). The type of cell death was identified by flow cytometry and the degree of monomer conversion (%DC) was determined by infrared spectroscopy (FTIR) after two photoactivation times (10 s or 20 s). Data were analyzed statistically by the Kruskal-Wallis and Mann-Whitney tests (α=0.05). Dentin saturation with ethanol resulted in higher necrotic cell death ratios for R3, R4 and R5 compared with water saturation, although R3 and R4 induced higher SDH production. Photoactivation for 20 s significantly improved the %DC of all EASs compared with 10 s. A significant positive correlation was observed between the degree of hydrophilicity and %DC, for both photoactivation times. In conclusion, except for R2, dentin saturation with ethanol increased the cytotoxicity of EASs, as expressed by the induction of necrotic cell death. PMID:23906501

  8. 20 CFR 641.800 - What uniform administrative requirements apply to the use of SCSEP funds?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... allowable cost requirements that apply to their type of organization. (OAA sec. 503(f)(2)). (b) Governments, State, local, and Indian Tribal Organizations that receive SCSEP funds under grants or cooperative.... (c) Nonprofit and commercial organizations, institutions of higher education, hospitals,...

  9. Applying non-uniform grids to evaluating susceptibility from flow-type phenomena: an example of application to Mount Etna

    NASA Astrophysics Data System (ADS)

    Bongolan, Vena Pearl; Lupiano, Valeria; D'Ambrosio, Donato; Rongo, Rocco; Spataro, William; Iovine, Giulio

    2013-04-01

    The hazard induced by dangerous flow-type phenomena - e.g. lava flows, earth flows, debris flows, and debris avalanches - can be assessed by analysing a proper set of simulations of hypothetical events. Non-uniform grids are commonly used to study particular areas of interest in computational domains. Examples of application concern, for instance, the turbulence in a boundary layer. While non-uniform grids frequently appear in adaptive methods, they may also be used in a "static" environment. A purposive sampling method, based on a non-uniform grid of sources coupled with numerical simulations of independent events, has recently been employed to evaluate the hazard induced by flow-type phenomena. An example of application to lava-flows at Mount Etna (Italy) is described in this study. The method aims at refining the spatial distribution of hypothetical eruptive vents with respect to an original uniform grid. The density of eruptive vents has been determined by considering the historical distribution of lateral and eccentric vents, and the distribution of the main faults/structures on the volcano. A higher number of sources marks higher-probability zones of vent opening, based on classes of activation: the number of vents in each class has been set proportionally to the probability of activation of the class. By considering the different types of eruption expected from the considered volcano, based on the historical activity of the past 400 years, a set of simulations per each vent has been performed. The employed model is SCIARA-fv2, a Cellular Automata numerical code recently applied to the same study area for preliminary hazard analyses. In this work, calibration could therefore be skipped, by taking advantage from such experience of tuning of the parameters. Performed simulations have been analysed by a GIS, to verify the number of events affecting each cell of the domain. A probability of occurrence could be assigned to each simulation, based on statistics of

  10. Local Arp2/3-dependent actin assembly modulates applied traction force during apCAM adhesion site maturation

    PubMed Central

    Buck, Kenneth B.; Schaefer, Andrew W.; Schoonderwoert, Vincent T.; Creamer, Matthew S.; Dufresne, Eric R.; Forscher, Paul

    2017-01-01

    Homophilic binding of immunoglobulin superfamily molecules such as the Aplysia cell adhesion molecule (apCAM) leads to actin filament assembly near nascent adhesion sites. Such actin assembly can generate significant localized forces that have not been characterized in the larger context of axon growth and guidance. We used apCAM-coated bead substrates applied to the surface of neuronal growth cones to characterize the development of forces evoked by varying stiffness of mechanical restraint. Unrestrained bead propulsion matched or exceeded rates of retrograde network flow and was dependent on Arp2/3 complex activity. Analysis of growth cone forces applied to beads at low stiffness of restraint revealed switching between two states: frictional coupling to retrograde flow and Arp2/3-dependent propulsion. Stiff mechanical restraint led to formation of an extensive actin cup matching the geometric profile of the bead target and forward growth cone translocation; pharmacological inhibition of the Arp2/3 complex or Rac attenuated F-actin assembly near bead binding sites, decreased the efficacy of growth responses, and blocked accumulation of signaling molecules associated with nascent adhesions. These studies introduce a new model for regulation of traction force in which local actin assembly forces buffer nascent adhesion sites from the mechanical effects of retrograde flow. PMID:27852899

  11. Evaluation of Biocompatibility of an Etch-and-Rinse Adhesive System Based in Tertiary Butanol Applied in Deep Cavity

    PubMed Central

    Alves, Gilvanely Cardoso; Sobral, Ana Paula Veras

    2015-01-01

    The aim of this study was to evaluate biocompatibility of an etch-and-rinse adhesive system based in tertiary butanol applied in deep cavity human teeth with approximately 1 mm of remaining dentin by observing histological changes of the pulp tissue of humans at intervals of 01, 07, 14 and 21 days. Twenty third molars with indication for xtraction from patients of both sexes, presenting no systemic alterations were used. Class I cavity was made deeper and then, XP BOND adhesive system and resin Filtek Z250 were applied. The sample was divided into four groups according to the time intervals between the application of adhesive system and extraction. Morphologic criteria analysed considered the presence of hyperemia, type of inflammatory cell response, organization of odontoblast cells layer, organization of pulp tissue and the presence or absence of bacteria. Data were submitted to Fisher Exact Test p> 0.05. We observed mild inflammatory infiltrate, preserved pulp tissue morphology, disorganization of the odontoblast layer in most specimens, as well as absence of bacteria at the intervals of 01, 07, 14 and 21 days. In some cases there was pulp hyperemia. The etchand- rinse adhesive system based in tertiary butanol showed satisfactory behavior in the conditions studied. PMID:26140062

  12. Basic and applied aspects of microbial adhesion at the hydrocarbon:water interface.

    PubMed

    Rosenberg, M

    1991-01-01

    Microbial hydrophobicity has been studied since 1924. During the last decade, various techniques have become available for measuring hydrophobic surface properties of microbial cells. This has led to a surge in investigations suggesting a role for hydrophobicity in adhesion of bacteria to an array of surfaces (oral surfaces, mineral particles, fatty meat, epithelial cells, phagocytes, biomaterials), partitioning at interfaces, as well as gliding mobility. The present manuscript comprises a critical, chronological look at the origins of microbial hydrophobicity research, its development, origins, and applications. Emphasis is placed on microbial adhesion to hydrocarbons, a technique with which the author has the most experience and research interest.

  13. Effect of etch-and-rinse and self-etching adhesive systems on hardness uniformity of resin cements after glass fiber post cementation

    PubMed Central

    Grande da Cruz, Fernanda Zander; Grande, Christiana Zander; Roderjan, Douglas Augusto; Galvão Arrais, César Augusto; Bührer Samra, Adriana Postiglione; Calixto, Abraham Lincoln

    2012-01-01

    Objective To evaluate the effects of etch-and-rinse and self-etching adhesive systems on Vickers hardness (VHN) uniformity of dual-cured resin cements after fiber post cementation. Methods: Fifty glass fiber posts were cemented into bovine roots using the following cementing systems: Prime&Bond 2.1 Dual Cure and Enforce with light-activation (PBDC-LCEN); Prime&Bond 2.1 and Enforce with light-activation (PB-CLEN); Prime&Bond 2.1 Dual Cure and Enforce without light exposure (PBDC-SCEN); ED Primer and Panavia 21 (ED-SCPN); and Clearfil SE Bond and Panavia 21 (CF-SCPN). The roots were stored in distilled water for 72 h and transversely sectioned into thirds (coronal, medium, and apical). The VHN values of the resin cement layers were measured close to the post and to the dentin wall on the transversely sectioned flat surfaces. The results were analyzed by three-way repeated measures analysis of variance (ANOVA) and Tukey’s post-hoc test (pre-set alpha of 5%). Results: Most resin cements presented higher VHN values near the post than near the dentin wall. The ED-SCPN group showed the highest VHN values regardless of the root third, while the self-cured group PBDC-SCEN exhibited the lowest values. The resin cements from the light-activated groups PBDC-LCEN and PB-LCEN showed lower VHN values at the apical third than at the coronal third. The VHN values were not influenced by the root third in self-cured groups PBDC-SCEN, ED-SCPN, and ED-SCPN. Conclusion: Depending on the product, bonding agents might promote changes in hardness uniformity of resin cements after post cementation. PMID:22904652

  14. In vitro analysis of bond strength of self-etching adhesives applied on superficial and deep dentin.

    PubMed

    Garcia, Eugenio J; Gomes, Osnara M M; Gomes, João C

    2009-01-01

    The purpose of this study was to evaluate the bond strength of three adhesive systems to superficial and deep dentine using the microtensile bond strength test (microTBS). The occlusal enamel of thirty human third molars was removed to expose a flat surface of superficial or deep dentin. For each type of surface, the test specimens were randomly divided into three groups which underwent the application of a conventional two-step adhesive system [Single Bond (SB)] as the control group (n=10), a two-bottle self-etching system [One Coat SE Bond (OCSE)] (n=10) and a one bottle one-step system [Clearfil S3 Bond (CFS3)] (n=10). Adhesives were applied, a 5-mm high "crown" as built-up with resin composite Z250 (3M) and the specimens with a cross-sectional area of 0.7 +/- 0.1 mm2 were tested in tension (0.5 mm/min). Four fractured sticks from each tooth were randomly selected and the dentin side was gently abraded with a 1200-grit SiC paper etched with 35% phosphoric acid for 15 s and air dried. SEM micrographs at 70X and 2400X magnification were taken using scanning electron microscopy (SEM) to calculate the area of tubular dentin (ATD) and tubular density (TD) with Image Pro Plus 5. Two-way ANOVA (dentin depth-adhesive) showed higher bond strength values for SB. However the values did not depend on dentin depth. Linear regression showed a significant relationship between bond strength and area of intertubular dentin for SB (p = 0.004), and a significant inverse relationship between tubular density and bond strength for CFS3 (p = 0.009). OCSE exhibited a tendency that was similar to SB and opposite to CFS3, but was not statistically significant. The conventional two-step adhesive had higher bond strength values. The use of digital image analysis facilitates the manipulation of data and contributes to the interpretation of the behavior of new adhesive systems.

  15. Frictional behavior and adhesion of Ag and Au films applied to aluminum oxide by oxygen-ion assisted Screen Cage Ion Plating (SCIP)

    NASA Technical Reports Server (NTRS)

    Spalvins, Talivaldis; Sliney, Harold E.

    1994-01-01

    A modified dc-diode ion plating system, by utilizing a metallic screen cage as a cathode, is introduced for coating nonconductors such as ceramics. Screen cage ion plating (SCIP) is used to apply Ag and Au lubricating films on aluminum oxide surfaces. This process has excellent ability to coat around corners to produce three-dimensional coverage of the substrate. A dramatic increase in adhesion is achieved when plating is performed in a reactive 50 percent O2 - 50 percent Ar glow discharge compared to the adhesion when plating is performed in 100 percent Ar. The presence of oxygen ion assistance contributes to the excellent adhesion as measured in a pull-type adhesion tester. The Ag and Au film adhesion is significantly increased (less than 70MPa) and generally exceeds the cohesion of the substrate such that portions of the alumina are pulled out.

  16. 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

  17. A long uniform taper applied to an all-fiber Tm3+ doped double-clad fiber laser

    NASA Astrophysics Data System (ADS)

    Zhang, Y. J.; Zhong, F. F.; He, W. B.; Zhang, Y.; Wang, Y.; Xu, J.; Ju, Y. L.

    2010-11-01

    A long uniform taper fabricated on a large mode area Tm3+-doped double-clad fiber laser, which was clad-pumped by a laser diode (LD), was found to be an effective wavelength filter while improving the output beam quality and narrowing the line-width significantly. The long uniform taper was fabricated directly on the multi-mode Tm3+-doped fiber by heating and stretching method, and located several centimeters before the output fiber end. By slightly bending the taper section, the output laser spectrum was left with only one peak with a line-width less than 0.5 nm, compared to the multi-peak spectrum with a 5 nm line-width before tapering, indicating that the multi-mode fiber could produce quasi-single wavelength output with a long uniform taper. The beam quality factor M 2 declined from 6.6 to 2.6 compared. Only a slight decrease in slope efficiency, from 19.2 to 17.5%, was observed. The main output wavelength had a blue shift of 8 nm.

  18. Ray-tracing WKB analysis of Whistler waves in non-uniform magnetic fields applied to space thrusters

    NASA Astrophysics Data System (ADS)

    Cardinali, A.; Melazzi, D.; Manente, M.; Pavarin, D.

    2014-02-01

    Radiofrequency magnetized cylindrical plasma sources are proposed for the development of space thrusters, whose thrust efficiency and specific impulse depend on the power coupled into the plasma. At this stage of research, emphasis has been on the absorption of Whistler wave energy by non-uniform plasmas but not much on the role played by the magneto-static confinement field, considered uniform, constant and aligned with the axis of the source. We present RAYWh (RAY-tracing Whistler), a three-dimensional (3D) ray-tracing solver for electromagnetic propagation and power deposition in cylindrical plasma sources for space plasma thrusters, where actual magnetic confinement configurations along with plasma density profiles are included. The propagation and absorption of Whistler waves are investigated by solving the 3D Maxwell-Vlasov model equations by a Wentzel-Kramers-Brillouin (WKB) asymptotic expansion. The reduced set of equations for the wave phase and for the square amplitude of the electric field is solved numerically by means of a modified Runge-Kutta algorithm. Unexpected cut-offs, resonances, radial reflections, mode conversions and power deposition profile of the excited waves are found, when realistic confinement magnetic fields are considered. An analysis of the influence of axial wavenumbers and the axial length of the system on the power deposition is presented.

  19. 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.

  20. Effect on plasma and etch-rate uniformity of controlled phase shift between rf voltages applied to powered electrodes in a triode capacitively coupled plasma reactor

    SciTech Connect

    Sung, Dougyong; Jeong, Sangmin; Park, Youngmin; Volynets, Vladimir N.; Ushakov, Andrey G.; Kim, Gon-Ho

    2009-01-15

    The influence of the phase shift between rf voltages applied to the powered electrodes on plasma parameters and etch characteristics was studied in a very high-frequency (VHF) capacitively coupled plasma (CCP) triode reactor. rf voltages at 100 MHz were simultaneously applied to the top and bottom electrodes having a controlled phase shift between them, which could be varied between 0 deg. and 360 deg. Several plasma and process characteristics were measured as a function of the phase shift: (i) radial profiles of plasma-emission intensity, (ii) line-of-sight averaged plasma-emission intensity, and (iii) radial profiles of blanket SiO{sub 2} etching rate over a 300 mm wafer. Radial profiles of plasma emission were obtained using the scanning optical probe. It has been shown that all the measured characteristics strongly depend on the phase shift: (i) plasma-emission intensity is minimal at phase shift equal to 0 deg. and maximal at 180 deg. for all radial positions, while the emission radial profile changes from bell-shaped distribution with considerable nonuniformity at 0 deg. to a much more flattened distribution at 180 deg.; (ii) line-of-sight averaged plasma-emission intensity shows a similar dependence on the phase shift with minimum and maximum at 0 deg. and 180 deg., respectively; and (iii) the etch-rate radial profile at 180 deg. shows a much better uniformity as compared to that at 0 deg. Some of these results can be qualitatively explained by the redistribution of plasma currents that flow between the electrodes and also from the electrodes to the grounded wall with the phase shift. We suggest that the phase-shift effect can be used to improve the plasma and etch-rate spatial uniformity in VHF-CCP triode reactors.

  1. Field-controlled adhesion in confined magnetorheological fluids

    NASA Astrophysics Data System (ADS)

    Miranda, Jose; Lira, Sergio

    2009-11-01

    The study of reversible, functional, and controllable adhesives is a matter of considerable practical interest, and academic research. We report the adhesive response of a magnetorheological fluid confined between two parallel plates under a probe-tack test, when it is subjected to an applied magnetic field. Our analytical approach is based on a Darcy-like law formulation which considers a magnetic field-dependent yield stress behavior. The adhesion force is calculated in closed-form for two different configurations produced by a Helmholtz coils setup: uniform perpendicular, and nonuniform radial magnetic fields. In both cases, we verify that adhesion force is hugely increased as a result of the field-dependent nature of the yield stress. This provides a versatile way to obtain a shear resistant, tough structural adhesive through magnetic means.

  2. Field-controlled adhesion in confined magnetorheological fluids

    NASA Astrophysics Data System (ADS)

    Lira, Sérgio A.; Miranda, José A.

    2009-10-01

    The study of reversible, functional, and controllable adhesives is a matter of considerable practical interest, and academic research. We report the adhesive response of a magnetorheological fluid confined between two parallel plates under a probe-tack test, when it is subjected to an applied magnetic field. Our analytical approach is based on a Darcy-like law formulation which considers a magnetic field-dependent yield stress behavior. The adhesion force is calculated in closed form for two different configurations produced by a Helmholtz coils setup: uniform perpendicular, and nonuniform radial magnetic fields. In both cases, we verify that adhesion force is hugely increased as a result of the field-dependent nature of the yield stress. This provides a versatile way to obtain a shear resistant, tough structural adhesive through magnetic means.

  3. 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.

  4. Uniform Continuity of POVMs

    NASA Astrophysics Data System (ADS)

    Beneduci, Roberto

    2014-10-01

    Recently a characterization of uniformly continuous POVMs and a necessary condition for a uniformly continuous POVM F to have the norm-1 property have been provided. Moreover it was proved that in the commutative case, uniform continuity corresponds to the existence of a Feller Markov kernel. We apply such results to the analysis of some relevant physical examples; i.e., the phase space localization observables, the unsharp phase observable and the unsharp number observable of which we study the uniform continuity, the norm-1 property and the existence of a Feller Markov kernel.

  5. Beneficial effect of Cu on Ti-Nb-Ta-Zr sputtered uniform/adhesive gum films accelerating bacterial inactivation under indoor visible light.

    PubMed

    Alhussein, Akram; Achache, Sofiane; Deturche, Regis; Sanchette, Frederic; Pulgarin, Cesar; Kiwi, John; Rtimi, Sami

    2017-04-01

    This article presents the evidence for the significant effect of copper accelerating the bacterial inactivation on Ti-Nb-Ta-Zr (TNTZ) sputtered films on glass up to a Cu content of 8.3 at.%. These films were deposited by dc magnetron co-sputtering of an alloy target Ti-23Nb-0.7Ta-2Zr (at.%) and a Cu target. The fastest bacterial inactivation of E. coli on this later TNTZ-Cu surface proceeded within ∼75min. The films deposited by magnetron sputtering are chemically homogenous. The film roughness evaluated by atomic force spectroscopy (AFM) on the TNTZ-Cu 8.3 at.% Cu sample presented an RMS-value of 20.1nm being the highest RMS of any Cu-sputtered TNTZ sample. The implication of the RMS value found for this sample leading to the fastest interfacial bacterial inactivation kinetics is also discussed. Values for the Young's modulus and hardness are reported for the TNTZ films in the presence of various Cu-contents. Evaluation of the bacterial inactivation kinetics of E. coli under low intensity actinic hospital light and in the dark was carried out. The stable repetitive bacterial inactivation was consistent with the extremely low Cu-ion release from the samples of 0.4 ppb. Evidence is presented by the bacterial inactivation dependence on the applied light intensity for the intervention of Cu as semiconductor CuO during the bacterial inactivation at the TNTZ-Cu interface. The mechanism of CuO-intervention under light is suggested based on the pH/and potential changes registered during bacterial disinfection.

  6. 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.

  7. Pulsed-coil magnet systems for applying uniform 10-30 T fields to centimeter-scale targets on Sandia's Z facility.

    PubMed

    Rovang, D C; Lamppa, D C; Cuneo, M E; Owen, A C; McKenney, J; Johnson, D W; Radovich, S; Kaye, R J; McBride, R D; Alexander, C S; Awe, T J; Slutz, S A; Sefkow, A B; Haill, T A; Jones, P A; Argo, J W; Dalton, D G; Robertson, G K; Waisman, E M; Sinars, D B; Meissner, J; Milhous, M; Nguyen, D N; Mielke, C H

    2014-12-01

    Sandia has successfully integrated the capability to apply uniform, high magnetic fields (10-30 T) to high energy density experiments on the Z facility. This system uses an 8-mF, 15-kV capacitor bank to drive large-bore (5 cm diameter), high-inductance (1-3 mH) multi-turn, multi-layer electromagnets that slowly magnetize the conductive targets used on Z over several milliseconds (time to peak field of 2-7 ms). This system was commissioned in February 2013 and has been used successfully to magnetize more than 30 experiments up to 10 T that have produced exciting and surprising physics results. These experiments used split-magnet topologies to maintain diagnostic lines of sight to the target. We describe the design, integration, and operation of the pulsed coil system into the challenging and harsh environment of the Z Machine. We also describe our plans and designs for achieving fields up to 20 T with a reduced-gap split-magnet configuration, and up to 30 T with a solid magnet configuration in pursuit of the Magnetized Liner Inertial Fusion concept.

  8. Pulsed-coil magnet systems for applying uniform 10-30 T fields to centimeter-scale targets on Sandia's Z facility

    NASA Astrophysics Data System (ADS)

    Rovang, D. C.; Lamppa, D. C.; Cuneo, M. E.; Owen, A. C.; McKenney, J.; Johnson, D. W.; Radovich, S.; Kaye, R. J.; McBride, R. D.; Alexander, C. S.; Awe, T. J.; Slutz, S. A.; Sefkow, A. B.; Haill, T. A.; Jones, P. A.; Argo, J. W.; Dalton, D. G.; Robertson, G. K.; Waisman, E. M.; Sinars, D. B.; Meissner, J.; Milhous, M.; Nguyen, D. N.; Mielke, C. H.

    2014-12-01

    Sandia has successfully integrated the capability to apply uniform, high magnetic fields (10-30 T) to high energy density experiments on the Z facility. This system uses an 8-mF, 15-kV capacitor bank to drive large-bore (5 cm diameter), high-inductance (1-3 mH) multi-turn, multi-layer electromagnets that slowly magnetize the conductive targets used on Z over several milliseconds (time to peak field of 2-7 ms). This system was commissioned in February 2013 and has been used successfully to magnetize more than 30 experiments up to 10 T that have produced exciting and surprising physics results. These experiments used split-magnet topologies to maintain diagnostic lines of sight to the target. We describe the design, integration, and operation of the pulsed coil system into the challenging and harsh environment of the Z Machine. We also describe our plans and designs for achieving fields up to 20 T with a reduced-gap split-magnet configuration, and up to 30 T with a solid magnet configuration in pursuit of the Magnetized Liner Inertial Fusion concept.

  9. Pulsed-coil magnet systems for applying uniform 10–30 T fields to centimeter-scale targets on Sandia's Z facility

    SciTech Connect

    Rovang, D. C. Lamppa, D. C.; Cuneo, M. E.; Owen, A. C.; McKenney, J.; Johnson, D. W.; Radovich, S.; Kaye, R. J.; McBride, R. D.; Alexander, C. S.; Awe, T. J.; Slutz, S. A.; Sefkow, A. B.; Haill, T. A.; Jones, P. A.; Argo, J. W.; Dalton, D. G.; Robertson, G. K.; Waisman, E. M.; Sinars, D. B.; and others

    2014-12-15

    Sandia has successfully integrated the capability to apply uniform, high magnetic fields (10–30 T) to high energy density experiments on the Z facility. This system uses an 8-mF, 15-kV capacitor bank to drive large-bore (5 cm diameter), high-inductance (1–3 mH) multi-turn, multi-layer electromagnets that slowly magnetize the conductive targets used on Z over several milliseconds (time to peak field of 2–7 ms). This system was commissioned in February 2013 and has been used successfully to magnetize more than 30 experiments up to 10 T that have produced exciting and surprising physics results. These experiments used split-magnet topologies to maintain diagnostic lines of sight to the target. We describe the design, integration, and operation of the pulsed coil system into the challenging and harsh environment of the Z Machine. We also describe our plans and designs for achieving fields up to 20 T with a reduced-gap split-magnet configuration, and up to 30 T with a solid magnet configuration in pursuit of the Magnetized Liner Inertial Fusion concept.

  10. Migration assessment and the 'Threshold of Toxicological Concern' applied to the safe-design of an acrylic adhesive for food contact laminates.

    PubMed

    Canellas, Elena; Vera, Paula; Nerín, Cristina

    2017-03-23

    Adhesives are widely used in food packaging. The suitability of an acrylic adhesive used on food packaging has been studied. Six potential migrants have been identified using GC-MS and UPLC-QTOF. Five compounds were intentionally added (2-butoxyethanol and 2,4,7,9-tetramethyl-5-decyne-4,7-diol (TMDD) and TMDD ethoxylates). Moreover, one of the compounds identified as 2-(12-(methacryloyloxy)dodecyl)malonic acid was a non-intenionally added substance (NIAS), that could be a methyl metacrylate derivative. This has demonstrated that the identification of compounds in food packaging is an essential step when the risk evaluation of the package is being studied. A migration study of the adhesive compounds from multilayers with the structure paper-adhesive-film was carried out. The films used for the multilayers were both non-biodegradable substrates (polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) and biodegradable substrates [polylactic acid (PLA) and Ecovio F2223® that is a mixture of biodegradable polyester with PLA]. All the non-volatile compounds, including the NIAS identified, migrated into the dry food simulant Tenax®. In fact the five compounds (surfactants) based on TMDD were found to migrate from all 5 laminates into Tenax® at levels from 0.05-0.6 mg/kg. The results showed that the lowest migration (0.01 mg/kg for 2-(12-(methacryloyloxy)dodecyl)malonic acid to 0.07 for TMDD mg/kg) occured when the compounds passed through the PLA demostrating its functional barrier properties to these compounds. On the contrary, PE (migration values from 0.11 mg/kg for 2-(12-(methacryloyloxy)dodecyl)malonic acid to 0.57 mg/kg for TMDD ethoxylate n=1 m=1) and Ecovio® (migration values from 0.1 mg/kg for 2-(12-(methacryloyloxy)dodecyl)malonic acid to 0.56 mg/kg for TMDD ethoxylate n=1 m=1) showed the worst barrier properties to these compounds. To evaluate the migration results the threshold of toxicological concern strategy was applied. The

  11. 25 CFR 10.6 - How is the BIA assured that the policies and standards are being applied uniformly and facilities...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAW AND ORDER INDIAN COUNTRY DETENTION FACILITIES AND...-mandatory detention standards and will document progress on uniform reporting. The BIA Office of Law Enforcement Services will conduct periodic operational evaluations for oversight....

  12. 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

  13. Quasilinear dynamics of a cloud of hot electrons propagating through a plasma in the presence of an externally applied uniform electric field

    NASA Astrophysics Data System (ADS)

    Foroutan, G.; Robinson, P. A.; Zahed, H.; Li, B.; Cairns, I. H.

    2007-12-01

    The propagation of a cloud of hot electrons through a plasma and the generation of Langmuir waves are investigated in the presence of an externally applied uniform electric field. Using numerical simulations of the quasilinear equations the evolution of the electron distribution function and the spectral density of Langmuir waves are monitored in coordinate and velocity space. It is found that the Langmuir waves are enhanced in the presence of the electric field and the distribution functions of the beam and Langmuir waves diffuse toward large velocities. The overall self-similar characteristic of the system is preserved in the presence of the electric field. The average beam velocity is no longer constant and increases with time along its trajectory, but the acceleration is much less than that of free streaming particles. The beam number density plateaus in coordinate space and large scale, small amplitude fluctuations develop on the top of this plateau. The level of the fluctuations depends on the strength of the electric field. We also investigated the influence of the external electric field on the evolution of gas-dynamical parameters such as the height of the plateau in the beam distribution function in velocity space, its upper velocity boundary, and the local velocity spread of the beam. Due to the finite quasilinear relaxation time and spatial inhomogeneity of the electron beam, different parts of the beam are in different states of relaxation. In the region of partial relaxation the plateau is specified by both upper and lower velocity boundaries. The upper boundary of plateau increases linearly with the strength of the electric field but the lower boundary is independent of it. Contrary to the free streaming of a beam in an electric field or quasilinear relaxation in the absence of the electric field, the local velocity spread of the beam increases during its propagation. Some of the electrons at the back of the beam are also transferred by the electric

  14. Quasilinear dynamics of a cloud of hot electrons propagating through a plasma in the presence of an externally applied uniform electric field

    SciTech Connect

    Foroutan, G.; Robinson, P. A.; Zahed, H.; Li, B.; Cairns, I. H.

    2007-12-15

    The propagation of a cloud of hot electrons through a plasma and the generation of Langmuir waves are investigated in the presence of an externally applied uniform electric field. Using numerical simulations of the quasilinear equations the evolution of the electron distribution function and the spectral density of Langmuir waves are monitored in coordinate and velocity space. It is found that the Langmuir waves are enhanced in the presence of the electric field and the distribution functions of the beam and Langmuir waves diffuse toward large velocities. The overall self-similar characteristic of the system is preserved in the presence of the electric field. The average beam velocity is no longer constant and increases with time along its trajectory, but the acceleration is much less than that of free streaming particles. The beam number density plateaus in coordinate space and large scale, small amplitude fluctuations develop on the top of this plateau. The level of the fluctuations depends on the strength of the electric field. We also investigated the influence of the external electric field on the evolution of gas-dynamical parameters such as the height of the plateau in the beam distribution function in velocity space, its upper velocity boundary, and the local velocity spread of the beam. Due to the finite quasilinear relaxation time and spatial inhomogeneity of the electron beam, different parts of the beam are in different states of relaxation. In the region of partial relaxation the plateau is specified by both upper and lower velocity boundaries. The upper boundary of plateau increases linearly with the strength of the electric field but the lower boundary is independent of it. Contrary to the free streaming of a beam in an electric field or quasilinear relaxation in the absence of the electric field, the local velocity spread of the beam increases during its propagation. Some of the electrons at the back of the beam are also transferred by the electric

  15. 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 ...

  16. Color Uniformity in Navy Uniforms.

    DTIC Science & Technology

    1980-05-01

    realized in contracting with a specific trouser, skirt, shirt or blouse manufacturer. Uniform items are issued on the basis of size and not on a top...Blue 3346 Spec. No.: MIL-C-29147 End Item: Men’s Winter Shirt Method of Issue: Stock Item - DPSC Procured Optional - NAVRESSO Method of Dyeing: Standard...Polyester Color: Blue 3346 Spec. No.: MIL-C-87051 End Item: Women’s Winter Shirt (new) Method of Issue: Stock Item - DPSC Procured Method of Dyeing: Piece

  17. Effect of non-isothermal deposition on surface morphology and microstructure of uniform molten aluminum alloy droplets applied to three-dimensional printing

    NASA Astrophysics Data System (ADS)

    Zuo, Han-song; Li, He-jun; Qi, Le-hua; Luo, Jun; Zhong, Song-yi; Wu, Yao-feng

    2015-01-01

    Non-isothermal deposition of uniform molten droplets as basic building blocks has a great influence on the geometric profile and microstructure of metallic components fabricated by the drop-based three-dimensional (3D) printing technology. In this paper, the thermal and dynamic behaviors of molten aluminum droplets during non-isothermal deposition were studied numerically and experimentally. The result shows that local solidification and interfacial re-melting occur during the initial period of non-isothermal deposition. The re-melting in microseconds depends greatly on the impacting droplet temperature, the deposition surface temperature, and the thermal contact resistance. Further, the coupling action of subsequent solidification and oscillation behaviors of aluminum droplet fixed on the target surface was also investigated. It is interesting to find that the formation and distribution of the solidified surface morphology, such as the typical micron-sized ripples, are significantly affected by layer-by-layer solidification and underdamped oscillation in the remaining molten metal. Based on the above research, a semiquantitative relationship between external morphology and internal microstructure was proposed, which was further certified by investigating the piled vertical columns. The works should be helpful for the process optimization and non-destructive detection of drop-based 3D printing techniques.

  18. 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.

  19. 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.

  20. Vortex dynamics in a thin superconducting film with a non-uniform magnetic field applied at its center with a small coil

    DOE PAGES

    Lemberger, Thomas R.; Loh, Yen Lee

    2016-10-27

    This article models the dynamics of vortices that are generated in the middle of a thin, large-area, superconducting film by a low-frequency magnetic field from a small coil, motivated by a desire to better understand measurements of the superconducting coherence length made with a two-coil apparatus. When the applied field exceeds a critical value, vortices and antivortices originate near the middle of the film at the radius where the Lorentz force of the screening supercurrent is largest. The Lorentz force from the screening supercurrent pushes vortices toward the center of the film and antivortices outward. In an experiment, vortices aremore » detected as an increase in mutual inductance between drive coil and a coaxial “pickup” coil on the opposite side of the film. Lastly, the model shows that the essential features of measurements are well described when vortex pinning and the attendant hysteresis are included.« less

  1. Vortex dynamics in a thin superconducting film with a non-uniform magnetic field applied at its center with a small coil

    SciTech Connect

    Lemberger, Thomas R.; Loh, Yen Lee

    2016-10-27

    This article models the dynamics of vortices that are generated in the middle of a thin, large-area, superconducting film by a low-frequency magnetic field from a small coil, motivated by a desire to better understand measurements of the superconducting coherence length made with a two-coil apparatus. When the applied field exceeds a critical value, vortices and antivortices originate near the middle of the film at the radius where the Lorentz force of the screening supercurrent is largest. The Lorentz force from the screening supercurrent pushes vortices toward the center of the film and antivortices outward. In an experiment, vortices are detected as an increase in mutual inductance between drive coil and a coaxial “pickup” coil on the opposite side of the film. Lastly, the model shows that the essential features of measurements are well described when vortex pinning and the attendant hysteresis are included.

  2. Vortex dynamics in a thin superconducting film with a non-uniform magnetic field applied at its center with a small coil

    NASA Astrophysics Data System (ADS)

    Lemberger, Thomas R.; Loh, Yen Lee

    2016-10-01

    This paper models the dynamics of vortices that are generated in the middle of a thin, large-area, superconducting film by a low-frequency magnetic field from a small coil, motivated by a desire to better understand measurements of the superconducting coherence length made with a two-coil apparatus. When the applied field exceeds a critical value, vortices and antivortices originate near the middle of the film at the radius where the Lorentz force of the screening supercurrent is largest. The Lorentz force from the screening supercurrent pushes vortices toward the center of the film and antivortices outward. In an experiment, vortices are detected as an increase in mutual inductance between the drive coil and a coaxial "pickup" coil on the opposite side of the film. The model shows that the essential features of measurements are well described when vortex pinning and the attendant hysteresis are included.

  3. Non-uniform object counting method in large-format pyramid images applied to CD31 vessel counting in whole-mount digital pathology sections

    NASA Astrophysics Data System (ADS)

    Murray, Mayan; Hill, Melissa L.; Liu, Kela; Mainprize, James G.; Yaffe, Martin J.

    2016-03-01

    Whole-mount pathology imaging has the potential to revolutionize clinical practice by preserving context lost when tissue is cut to fit onto conventional slides. Whole-mount digital images are very large, ranging from 4GB to greater than 50GB, making concurrent processing infeasible. Block-processing is a method commonly used to divide the image into smaller blocks and process them individually. This approach is useful for certain tasks, but leads to over-counting objects located on the seams between blocks. This issue is exaggerated as the block size decreases. In this work we apply a novel technique to enumerate vessels, a clinical task that would benefit from automation in whole-mount images. Whole-mount sections of rabbit VX2 tumors were digitized. Color thresholding was used to segment the brown CD31- DAB stained vessels. This vessel enumeration was applied to the entire whole-mount image in two distinct phases of block-processing. The first (whole-processing) phase used a basic grid and only counted objects that did not intersect the block's borders. The second (seam-processing) phase used a shifted grid to ensure all blocks captured the block-seam regions from the original grid. Only objects touching this seam-intersection were counted. For validation, segmented vessels were randomly embedded into a whole-mount image. The technique was tested on the image using 24 different block-widths. Results indicated that the error reaches a minimum at a block-width equal to the maximum vessel length, with no improvement as the block-width increases further. Object-density maps showed very good correlation between the vessel-dense regions and the pathologist outlined tumor regions.

  4. 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 ...

  5. 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.

  6. Uniform acceleration in general relativity

    NASA Astrophysics Data System (ADS)

    Friedman, Yaakov; Scarr, Tzvi

    2015-10-01

    We extend de la Fuente and Romero's (Gen Relativ Gravit 47:33, 2015) defining equation for uniform acceleration in a general curved spacetime from linear acceleration to the full Lorentz covariant uniform acceleration. In a flat spacetime background, we have explicit solutions. We use generalized Fermi-Walker transport to parallel transport the Frenet basis along the trajectory. In flat spacetime, we obtain velocity and acceleration transformations from a uniformly accelerated system to an inertial system. We obtain the time dilation between accelerated clocks. We apply our acceleration transformations to the motion of a charged particle in a constant electromagnetic field and recover the Lorentz-Abraham-Dirac equation.

  7. Applying Uniform Polymer Coatings To Microspheres

    NASA Technical Reports Server (NTRS)

    Lee, M. C.

    1985-01-01

    Acoustic levitation yields even coating on glass microsphres. Automatic Coating Apparatus injects polymer into acoustic levitator, moves glass sphere into polymer, dries polymer, and removes coated sphere. Apparatus injects more polymer for coating another sphere, and cycle repeats.

  8. 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.

  9. 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.

  10. 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.

  11. Do School Uniforms Fit?

    ERIC Educational Resources Information Center

    White, Kerry A.

    2000-01-01

    In 1994, Long Beach (California) Unified School District began requiring uniforms in all elementary and middle schools. Now, half of all urban school systems and many suburban schools have uniform policies. Research on uniforms' effectiveness is mixed. Tightened dress codes may be just as effective and less litigious. (MLH)

  12. School Uniforms Redux.

    ERIC Educational Resources Information Center

    Dowling-Sendor, Benjamin

    2002-01-01

    Reviews a recent decision in "Littlefield" by the 5th Circuit upholding a school uniform policy. Advises board member who wish to adopt a school uniform policy to solicit input from parents and students, research the experiences of other school districts with uniform policies, and articulate the interests they wish to promote through uniform…

  13. Should Students Wear Uniforms?

    ERIC Educational Resources Information Center

    Cohn, Carol A.; Siegel, Loren

    1996-01-01

    Two essays present opposing viewpoints on school uniforms. One suggests that uniforms make safer schools and better students. The other states that teenagers will rebel, and the uniform debate is a diversion from more pressing problems in education. The article includes brief opinion statements from teachers and other professionals. (SM)

  14. Charge contribution to patch-charged microparticle adhesion

    NASA Astrophysics Data System (ADS)

    Vallabh, Chaitanya Krishna Prasad; Vahdat, Armin Saeedi; Cetinkaya, Cetin

    2014-11-01

    Microparticle adhesion influenced by electrostatic charge has been a significant research interest for over past three decades or so in a wide spectrum of areas of interest from manufacturing (electrophotography, powder technology, metallurgy, and semi-conductor manufacturing) to natural phenomena (desert sandstorms and northern lights (auroras)). However, over the years, as a result of the strong discrepancies between the experimental adhesion measurements data and theoretical predictions, some key issues regarding the contributors of adhesion forces in charged microparticles and the nature of surface charge distribution still remain unresolved. In the current work, a non-contact ultrasonic approach is presented and employed for understanding the nature of charge distribution on a single microparticle and determining the effect of electrostatic charge on its adhesion in a non-invasive manner. From the vibrational spectra of the charged particle response to the ultrasonic substrate oscillations under various electrostatic loading conditions, three distinct shifting patterns of vibrational (rocking) resonance frequencies are observed for each level of applied substrate surface voltage, implying an un-symmetric force field on the particle, thus depicting non-uniform non-symmetric surface charge distribution on its surface. Also, a simple mathematical model was presented and employed for predicting the equivalent bulk charge on a single microparticle (toner) from resonance frequency shifts. In summary, it is found that the charge levels reported here are consistent with the previously published data, and it is demonstrated that, in a non-invasive manner, non-uniform charge distribution on a single microparticle can be observed and its total charge can be predicted.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. Assessment of starch-based wood adhesive quality by confocal Raman microscopic detection of reaction homogeneity.

    PubMed

    Wang, Panjun; Cheng, Li; Gu, Zhengbiao; Li, Zhaofeng; Hong, Yan

    2015-10-20

    Confocal Raman microscopy (CRM) was used to detect the reaction homogeneity of vinyl acetate grafted on starch granules and help to assess the quality of high solid content starch-based wood adhesive (HSSWA). Primarily, four experimental starch samples were investigated, and by analysis of band area ratio (carbonyl/carbohydrate) of each granule, information about reaction homogeneity was collected. The results showed that reaction extent and homogeneity were inconsistent for samples with different G values, and the distribution of ester groups on blend samples was much less uniform than grafted starch samples with the same G value, confirming that CRM was useful for determining the homogeneity of chemical modification. Afterwards, the technique was applied to research HSSWA prepared by two-stage seeded polymerization and traditional process. The distribution of ester groups was more uniform among starch granules prepared by former method, resulted in adhesive with much better performance, indicating that uniformity of polymerization was an important factor related to properties of starch-based wood adhesive.

  2. 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.

  3. 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.

  4. Dress Codes and Uniforms.

    ERIC Educational Resources Information Center

    Lumsden, Linda; Miller, Gabriel

    2002-01-01

    Students do not always make choices that adults agree with in their choice of school dress. Dress-code issues are explored in this Research Roundup, and guidance is offered to principals seeking to maintain a positive school climate. In "Do School Uniforms Fit?" Kerry White discusses arguments for and against school uniforms and summarizes the…

  5. Uniform magnesium oxide adsorbents

    NASA Technical Reports Server (NTRS)

    Dash, J. G.; Ecke, R.; Stoltenberg, J.; Vilches, O. E.; Whittemore, O. J., Jr.

    1978-01-01

    Kr adsorption on MgO is used to characterize the surface uniformity of MgO smoke and thermally decomposed Mg(OH)2. It is found that initially heterogeneous samples develop progressively sharper stepwise isotherms with increasingly-high-temperature heat treatment, apparently due to the removal of imperfections and high-energy facets, leaving surfaces of highly uniform (100) planes.

  6. School Uniforms. Research Brief

    ERIC Educational Resources Information Center

    Walker, Karen

    2007-01-01

    Does clothing make the person or does the person make the clothing? How does what attire a student wears to school affect their academic achievement? In 1996, President Clinton cited examples of school violence and discipline issues that might have been avoided had the students been wearing uniforms ("School uniforms: Prevention or suppression?").…

  7. Manual on School Uniforms.

    ERIC Educational Resources Information Center

    Department of Justice, Washington, DC.

    In response to growing levels of violence in American schools, many communities are deciding to adopt school-uniform policies as part of an overall program to improve school safety and discipline. This document provides the following guidelines for parents, teachers, and school leaders who may consider adopting a school-uniform policy: (1) Get…

  8. 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.

  9. Research of Adhesion Bonds Between Gas-Thermal Coating and Pre-Modified Base

    NASA Astrophysics Data System (ADS)

    Kovalevskaya, Z.; Zaitsev, K.; Klimenov, V.

    2016-08-01

    Nature of adhesive bonds between gas-thermal nickel alloy coating and carbon steel base was examined using laser profilometry, optical metallography, transmission and scanning electron microscopy. The steel surface was plastically pre-deformed by an ultrasonic tool. Proved that ultrasound pre-treatment modifies the steel surface. Increase of dislocation density and formation of sub micro-structure are base elements of surface modification. While using high-speed gas-flame, plasma and detonation modes of coatings, surface activation occurs and durable adhesion is formed. Ultrasonic pre-treatment of base material is effective when sprayed particles and base material interact through physical-chemical bond formation. Before applying high-speed gas flame and plasma sprayed coatings, authors recommend ultrasonic pretreatment, which creates periodic wavy topography with a stroke of 250 microns on the steel surface. Before applying detonation sprayed coatings, authors recommend ultrasound pretreatment that create modified surface with a uniform micro-topography.

  10. Endothelial cell migration on surfaces modified with immobilized adhesive peptides.

    PubMed

    Kouvroukoglou, S; Dee, K C; Bizios, R; McIntire, L V; Zygourakis, K

    2000-09-01

    Endothelial cell (EC) migration has been studied on aminophase surfaces with covalently bound RGDS and YIGSRG cell adhesion peptides. The fluorescent marker dansyl chloride was used to quantify the spatial distribution of the peptides on the modified surfaces. Peptides appeared to be distributed in uniformly dispersed large clusters separated by areas of lower peptide concentrations. We employed digital time-lapse video microscopy and image analysis to monitor EC migration on the modified surfaces and to reconstruct the cell trajectories. The persistent random walk model was then applied to analyze the cell displacement data and compute the mean root square speed, the persistence time, and the random motility coefficient of EC. We also calculated the time-averaged speed of cell locomotion. No differences in the speed of cell locomotion on the various substrates were noted. Immobilization of the cell adhesion peptides (RGDS and YIGSRG), however, significantly increased the persistence of cell movement and, thus, the random motility coefficient. These results suggest that immobilization of cell adhesion peptides on the surface of implantable biomaterials may lead to enhanced endothelization rates.

  11. 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.

  12. 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.

  13. 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.

  14. Catechol-functionalized adhesive polymer nanoparticles for controlled local release of bone morphogenetic protein-2 from titanium surface.

    PubMed

    Lee, Hong Jae; Koo, Ahn Na; Lee, Suk Won; Lee, Myung Hyun; Lee, Sang Cheon

    2013-09-10

    We report on a novel surface functionalization approach to equip the titanium (Ti) surfaces with osteogenic properties. A key feature of the approach is the treatment of the Ti surfaces with Ti-adhesive nanoparticles that can stably load and controllably release bone morphogenetic protein-2 (BMP-2). Ti-adhesive nanoparticles were prepared by self-assembly of a catechol-functionalized poly(amino acid) diblock copolymer, catechol-poly(L-aspartic acid)-b-poly(L-phenylalanine) (Cat-PAsp-PPhe). The nanoparticles consist of Ti-adhesive peripheral catechol groups, anionic PAsp shells, and PPhe inner cores. Field-emission scanning electron microscopy (Fe-SEM) images showed that the Ti-adhesive nanoparticles could be uniformly immobilized on Ti surfaces. X-ray photoelectron spectroscopy (XPS) confirmed the successful anchoring of nanoparticles onto Ti surfaces. After surface immobilization of the nanoparticles, the static water contact angle of the Ti substrate decreased from 75.3° to 50.0° or 36.4°, depending on the surface nanoparticle. Fluorescence microscopic analysis showed that BMP-2 could be effectively incorporated onto the Ti surface with adhesive nanoparticles. BMP-2 was controllably released for up to 40 days. The Ti substrate functionalized with BMP-2-incorporated nanoparticles significantly promoted attachment, proliferation, spreading, and alkaline phosphatase (ALP) activity of human adipose-derived stem cell (hADSC). The catechol-functionalized adhesive nanoparticles may be applied to various medical devices to create surfaces for improved performance.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. Uniform line integral representation of edge-diffracted fields.

    PubMed

    Umul, Yusuf Z

    2008-01-01

    A uniform line integral representation is derived for edge-diffracted fields by using the modified theory of physical optics and uniform asymptotic evaluation methods. The method is applied to the problem of diffraction of plane waves by a semi-infinite edge, which creates tip-diffracted fields with edge-diffracted waves. The uniform diffracted fields are plotted and examined numerically.

  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. 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...

  5. 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...

  6. 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...

  7. 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.

  8. 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.

  9. 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

  10. The Uniformity Illusion.

    PubMed

    Otten, Marte; Pinto, Yair; Paffen, Chris L E; Seth, Anil K; Kanai, Ryota

    2017-01-01

    Vision in the fovea, the center of the visual field, is much more accurate and detailed than vision in the periphery. This is not in line with the rich phenomenology of peripheral vision. Here, we investigated a visual illusion that shows that detailed peripheral visual experience is partially based on a reconstruction of reality. Participants fixated on the center of a visual display in which central stimuli differed from peripheral stimuli. Over time, participants perceived that the peripheral stimuli changed to match the central stimuli, so that the display seemed uniform. We showed that a wide range of visual features, including shape, orientation, motion, luminance, pattern, and identity, are susceptible to this uniformity illusion. We argue that the uniformity illusion is the result of a reconstruction of sparse visual information (from the periphery) based on more readily available detailed visual information (from the fovea), which gives rise to a rich, but illusory, experience of peripheral vision.

  11. 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.

  12. 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

  13. Uniform-droplet spray forming

    SciTech Connect

    Blue, C.A.; Sikka, V.K.; Chun, Jung-Hoon; Ando, T.

    1997-04-01

    The uniform-droplet process is a new method of liquid-metal atomization that results in single droplets that can be used to produce mono-size powders or sprayed-on to substrates to produce near-net shapes with tailored microstructure. The mono-sized powder-production capability of the uniform-droplet process also has the potential of permitting engineered powder blends to produce components of controlled porosity. Metal and alloy powders are commercially produced by at least three different methods: gas atomization, water atomization, and rotating disk. All three methods produce powders of a broad range in size with a very small yield of fine powders with single-sized droplets that can be used to produce mono-size powders or sprayed-on substrates to produce near-net shapes with tailored microstructures. The economical analysis has shown the process to have the potential of reducing capital cost by 50% and operating cost by 37.5% when applied to powder making. For the spray-forming process, a 25% savings is expected in both the capital and operating costs. The project is jointly carried out at Massachusetts Institute of Technology (MIT), Tuffs University, and Oak Ridge National Laboratory (ORNL). Preliminary interactions with both finished parts and powder producers have shown a strong interest in the uniform-droplet process. Systematic studies are being conducted to optimize the process parameters, understand the solidification of droplets and spray deposits, and develop a uniform-droplet-system (UDS) apparatus appropriate for processing engineering alloys.

  14. Radially uniform electron source

    NASA Technical Reports Server (NTRS)

    Mccomas, D.; Bame, S. J.

    1982-01-01

    A thermionic electron source capable of producing uniform count rates in a number of channel electron multipliers simultaneously was required for conditioning multipliers for an extended space mission. It was found that a straight tungsten filament in the center of a cylindrically symmetric geometry surrounded by an array of multipliers emits a radially asymmetric distribution of electrons that changes with time. A source was developed which successfully produces a time-independent radially uniform distribution of electrons by moving the filament out of the direct line of sight and replacing it with a centrally located electron 'cloud.'

  15. 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.

  16. [Musculoskeletal rehabilitation and bone. A novel approach to mechanotransduction using cell-adhesion-patterned cells].

    PubMed

    Katanosaka, Yuki; Naruse, Keiji

    2010-04-01

    Human vascular endothelial cells form the interface between the bloodstream and vessel walls and are continuously subjected to mechanical stimulation. When endothelial cells are stretched cyclically, along one axis, they align perpendicular to the axis of stretch. We previously reported that applying a cyclic, uni-axial strain to cells induced tyrosine phosphorylation of focal adhesion kinase and stimulated mitogen-activated protein kinase. However, it is difficult to quantify and analyze the spatial distribution of tyrosine phosphorylation in these cells, as they form focal adhesions randomly. Recently, we developed a system to overcome this problem by preparing individual, uniform, patterned cells that could be stretched cyclically and uni-axially. In this system we were able to statistically analyze cellular responses in these patterned cells, when subjected to a cyclic, uni-axial strain, using fluorescent microscopy.

  17. Uniformity in Tetrahedral Hohlraums

    NASA Astrophysics Data System (ADS)

    Craxton, R. S.; Schnittman, J. D.; Pollaine, S. M.

    1996-11-01

    Tetrahedral hohlraums, i.e., spherical hohlraums with four laser entrance holes (LEH's), offer an alternative means of obtaining good time-independent capsule irradiation uniformity. Since the laser spots are spread fairly uniformly over the hohlraum wall, time-dependent uniformity swings are minimized. Using the 3-D view-factor code BUTTERCUP we have found, for both OMEGA and the NIF, that the uniformity is typically ~2% rms at all times, mainly in the Y_32 mode, but can be reduced to ~1% by independently varying the power in each beam. We have investigated the sensitivity of tetrahedral hohlraums to errors in beam-energy balance and pointing, and we have examined how large the LEH's must be to allow the beams to go through without refraction or absorption. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460. *Also Lawrence Livermore National Laboratory.

  18. Custom uniform source system

    NASA Technical Reports Server (NTRS)

    Balcom, John L.

    1994-01-01

    The purpose and scope of this final report is to provide information on the Custom Uniform Source System (CSTM-USS-4000). The report includes documentation and summaries of the results for the work performed under the contract. The Annex contain laboratory test findings, photographs, and drawings of the sphere system.

  19. A new algorithm for computational image analysis of deformable motion at high spatial and temporal resolution applied to root growth. Roughly uniform elongation in the meristem and also, after an abrupt acceleration, in the elongation zone.

    PubMed

    van der Weele, Corine M; Jiang, Hai S; Palaniappan, Krishnan K; Ivanov, Viktor B; Palaniappan, Kannapan; Baskin, Tobias I

    2003-07-01

    A requirement for understanding morphogenesis is being able to quantify expansion at the cellular scale. Here, we present new software (RootflowRT) for measuring the expansion profile of a growing root at high spatial and temporal resolution. The software implements an image processing algorithm using a novel combination of optical flow methods for deformable motion. The algorithm operates on a stack of nine images with a given time interval between each (usually 10 s) and quantifies velocity confidently at most pixels of the image. The root does not need to be marked. The software calculates components of motion parallel and perpendicular to the local tangent of the root's midline. A variation of the software has been developed that reports the overall root growth rate versus time. Using this software, we find that the growth zone of the root can be divided into two distinct regions, an apical region where the rate of motion, i.e. velocity, rises gradually with position and a subapical region where velocity rises steeply with position. In both zones, velocity increases almost linearly with position, and the transition between zones is abrupt. We observed this pattern for roots of Arabidopsis, tomato (Lycopersicon lycopersicum), lettuce (Lactuca sativa), alyssum (Aurinia saxatilis), and timothy (Phleum pratense). These velocity profiles imply that relative elongation rate is regulated in a step-wise fashion, being low but roughly uniform within the meristem and then becoming high, but again roughly uniform, within the zone of elongation. The executable code for RootflowRT is available from the corresponding author on request.

  20. A New Algorithm for Computational Image Analysis of Deformable Motion at High Spatial and Temporal Resolution Applied to Root Growth. Roughly Uniform Elongation in the Meristem and Also, after an Abrupt Acceleration, in the Elongation Zone1

    PubMed Central

    van der Weele, Corine M.; Jiang, Hai S.; Palaniappan, Krishnan K.; Ivanov, Viktor B.; Palaniappan, Kannapan; Baskin, Tobias I.

    2003-01-01

    A requirement for understanding morphogenesis is being able to quantify expansion at the cellular scale. Here, we present new software (RootflowRT) for measuring the expansion profile of a growing root at high spatial and temporal resolution. The software implements an image processing algorithm using a novel combination of optical flow methods for deformable motion. The algorithm operates on a stack of nine images with a given time interval between each (usually 10 s) and quantifies velocity confidently at most pixels of the image. The root does not need to be marked. The software calculates components of motion parallel and perpendicular to the local tangent of the root's midline. A variation of the software has been developed that reports the overall root growth rate versus time. Using this software, we find that the growth zone of the root can be divided into two distinct regions, an apical region where the rate of motion, i.e. velocity, rises gradually with position and a subapical region where velocity rises steeply with position. In both zones, velocity increases almost linearly with position, and the transition between zones is abrupt. We observed this pattern for roots of Arabidopsis, tomato (Lycopersicon lycopersicum), lettuce (Lactuca sativa), alyssum (Aurinia saxatilis), and timothy (Phleum pratense). These velocity profiles imply that relative elongation rate is regulated in a step-wise fashion, being low but roughly uniform within the meristem and then becoming high, but again roughly uniform, within the zone of elongation. The executable code for RootflowRT is available from the corresponding author on request. PMID:12857796

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. A Single-Lap Joint Adhesive Bonding Optimization Method Using Gradient and Genetic Algorithms

    NASA Technical Reports Server (NTRS)

    Smeltzer, Stanley S., III; Finckenor, Jeffrey L.

    1999-01-01

    A natural process for any engineer, scientist, educator, etc. is to seek the most efficient method for accomplishing a given task. In the case of structural design, an area that has a significant impact on the structural efficiency is joint design. Unless the structure is machined from a solid block of material, the individual components which compose the overall structure must be joined together. The method for joining a structure varies depending on the applied loads, material, assembly and disassembly requirements, service life, environment, etc. Using both metallic and fiber reinforced plastic materials limits the user to two methods or a combination of these methods for joining the components into one structure. The first is mechanical fastening and the second is adhesive bonding. Mechanical fastening is by far the most popular joining technique; however, in terms of structural efficiency, adhesive bonding provides a superior joint since the load is distributed uniformly across the joint. The purpose of this paper is to develop a method for optimizing single-lap joint adhesive bonded structures using both gradient and genetic algorithms and comparing the solution process for each method. The goal of the single-lap joint optimization is to find the most efficient structure that meets the imposed requirements while still remaining as lightweight, economical, and reliable as possible. For the single-lap joint, an optimum joint is determined by minimizing the weight of the overall joint based on constraints from adhesive strengths as well as empirically derived rules. The analytical solution of the sin-le-lap joint is determined using the classical Goland-Reissner technique for case 2 type adhesive joints. Joint weight minimization is achieved using a commercially available routine, Design Optimization Tool (DOT), for the gradient solution while an author developed method is used for the genetic algorithm solution. Results illustrate the critical design variables

  7. 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.

  8. 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.

  9. Effect of channel geometry on cell adhesion in microfluidic devices.

    PubMed

    Green, James V; Kniazeva, Tatiana; Abedi, Mehdi; Sokhey, Darshan S; Taslim, Mohammad E; Murthy, Shashi K

    2009-03-07

    Microfluidic channels coated with ligands are a versatile platform for the separation or enrichment of cells from small sample volumes. This adhesion-based mode of separation is mediated by ligand-receptor bonds between the cells and channel surface and also by fluid shear stress. This paper demonstrates how aspects of microchannel geometry can play an additional role in controlling cell adhesion. With a combination of computational fluid dynamics modeling and cell adhesion experiments, channels with sharp turns are shown to have regions with near-zero velocity at the turn regions where large numbers of cells adhere or become collected. The lack of uniform adhesion in the turn regions compared to other regions of these channels, together with the large variability in observed cell adhesion indicates that channels with sharp turns are not optimal for cell-capture applications where predictable cell adhesion is desired. Channels with curved turns, on the other hand are shown to provide more uniform and predictable cell adhesion provided the gap between parallel arms of the channels is sufficiently wide. The magnitude of cell adhesion in these curved channels is comparable to that in straight channels with no turns.

  10. 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.

  11. 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.

  12. 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.

  13. Composites with improved fiber-resin interfacial adhesion

    NASA Technical Reports Server (NTRS)

    Cizmecioglu, Muzaffer (Inventor)

    1989-01-01

    The adhesion of fiber reinforcement such as high modulus graphite to a matrix resin such as polycarbonate is greatly enhanced by applying a very thin layer, suitably from 50 Angstroms to below 1000 Angstroms, to the surface of the fiber such as by immersing the fiber in a dilute solution of the matrix resin in a volatile solvent followed by draining to remove excess solution and air drying to remove the solvent. The thin layer wets the fiber surface. The very dilute solution of matrix resin is able to impregnate multifilament fibers and the solution evenly flows onto the surface of the fibers. A thin uniform layer is formed on the surface of the fiber after removal of the solvent. The matrix resin coated fiber is completely wetted by the matrix resin during formation of the composite. Increased adhesion of the resin to the fibers is observed at fracture. At least 65 percent of the surface of the graphite fiber is covered with polycarbonate resin at fracture whereas uncoated fibers have very little matrix resin adhering to their surfaces at fracture and epoxy sized graphite fibers exhibit only slightly higher coverage with matrix resin at fracture. Flexural modulus of the composite containing matrix resin coated fibers is increased by 50 percent and flexural strength by 37 percent as compared to composites made with unsized fibers.

  14. Uniform spray coating for large tanks

    NASA Technical Reports Server (NTRS)

    Carter, J. M.

    1977-01-01

    System employs spray facility located within ventilated plastic booth to uniformly coat exterior of large cylindrical tanks with polyurethane foam insulation. Coating target is rotated on turntable while movable spray guns apply overlapping spirals of foam. Entire operation may be controlled by single operator from remote station.

  15. Content uniformity and assay requirements in current regulations.

    PubMed

    Bánfai, Balázs; Ganzler, Katalin; Kemény, Sándor

    2007-07-13

    The acceptance of a tablet batch is based both on the content uniformity test and on the assay. It is shown that these two characteristics are not independent, and the acceptance criteria for them are not even consistent. For content uniformity range three methods of calculation are compared: the present European Pharmacopoeia method, a tolerance range method with improved k tolerance factor and a one-way random effects analysis of variance model. To resolve the inconsistency several options are discussed: applying the holistic content uniformity range alone; using content uniformity standard deviation and assay mean simultaneously or applying a criterion based on Taguchi's quadratic loss function.

  16. Should School Nurses Wear Uniforms?

    ERIC Educational Resources Information Center

    Journal of School Health, 2001

    2001-01-01

    This 1958 paper questions whether school nurses should wear uniforms (specifically, white uniforms). It concludes that white uniforms are often associated with the treatment of ill people, and since many people have a fear reaction to them, they are not necessary and are even undesirable. Since school nurses are school staff members, they should…

  17. 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.

  18. 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.

  19. Uniform quantized electron gas

    NASA Astrophysics Data System (ADS)

    Høye, Johan S.; Lomba, Enrique

    2016-10-01

    In this work we study the correlation energy of the quantized electron gas of uniform density at temperature T  =  0. To do so we utilize methods from classical statistical mechanics. The basis for this is the Feynman path integral for the partition function of quantized systems. With this representation the quantum mechanical problem can be interpreted as, and is equivalent to, a classical polymer problem in four dimensions where the fourth dimension is imaginary time. Thus methods, results, and properties obtained in the statistical mechanics of classical fluids can be utilized. From this viewpoint we recover the well known RPA (random phase approximation). Then to improve it we modify the RPA by requiring the corresponding correlation function to be such that electrons with equal spins can not be on the same position. Numerical evaluations are compared with well known results of a standard parameterization of Monte Carlo correlation energies.

  20. The Uniform Rugosity Effect

    NASA Astrophysics Data System (ADS)

    Bonnivard, Matthieu; Bucur, Dorin

    2012-06-01

    Relying on the effect of microscopic asperities, one can mathematically justify that viscous fluids adhere completely on the boundary of an impermeable domain. The rugosity effect accounts asymptotically for the transformation of complete slip boundary conditions on a rough surface in total adherence boundary conditions, as the amplitude of the rugosities vanishes. The decreasing rate (average velocity divided by the amplitude of the rugosities) computed on close flat layers is definitely influenced by the geometry. Recent results prove that this ratio has a uniform upper bound for certain geometries, like periodical and "almost Lipschitz" boundaries. The purpose of this paper is to prove that such a result holds for arbitrary (non-periodical) crystalline boundaries and general (non-smooth) periodical boundaries.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Influence of different tooth types on the bond strength of two orthodontic adhesive systems

    PubMed Central

    Öztürk, Bora; Koyutürk, Alp Erdin; Çatalbaş, Bülent; Özer, Füsun

    2008-01-01

    The aim of this investigation was to evaluate the effects of different tooth types on the shear bond strength (SBS) of two orthodontic resin adhesive systems in vitro. Two hundred extracted sound human teeth were used in the study. Ten teeth of each tooth type were the mounted in acrylic resin leaving the buccal surface of the crowns parallel to the base of the moulds. In each experimental group, the adhesives (Transbond XT™ and Light Bond™) were applied to the etched enamel surfaces. The orthodontic composite resins were then applied to the surface in cylindrical-shaped plastic matrices. For SBS testing, a force transducer (Ultradent™) was applied at a crosshead speed of 1 mm/minute at the interface between the tooth and composite until failure occurred. Data were analysed using two-way analysis of variance (ANOVA), Kruskal–Wallis one-way ANOVA, a Bonferroni adjusted Mann–Whitney U-test, and an independent t-test. Generally, it was found that tooth type had a significant effect on SBS (P < 0.05) with Light Bond™ showing a higher SBS than Transbond XT™ (P < 0.05). The highest bond strengths were observed for the upper central incisor and lower molars with Light Bond™ (P < 0.05) and the lowest mean bond strengths for the upper molars and lower canine with Transbond XT™ (P <0.05). The results demonstrated that enamel SBS was significantly altered by both tooth type and adhesive system. Thus, the findings of this study confirm that enamel bond strength is not uniform for all teeth. These results may also explain the variability in the enamel-bonding efficacy of adhesives. PMID:18678760

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. A non-local evolution equation model of cell–cell adhesion in higher dimensional space

    PubMed Central

    Dyson, Janet; Gourley, Stephen A.; Webb, Glenn F.

    2013-01-01

    A model for cell–cell adhesion, based on an equation originally proposed by Armstrong et al. [A continuum approach to modelling cell–cell adhesion, J. Theor. Biol. 243 (2006), pp. 98–113], is considered. The model consists of a nonlinear partial differential equation for the cell density in an N-dimensional infinite domain. It has a non-local flux term which models the component of cell motion attributable to cells having formed bonds with other nearby cells. Using the theory of fractional powers of analytic semigroup generators and working in spaces with bounded uniformly continuous derivatives, the local existence of classical solutions is proved. Positivity and boundedness of solutions is then established, leading to global existence of solutions. Finally, the asymptotic behaviour of solutions about the spatially uniform state is considered. The model is illustrated by simulations that can be applied to in vitro wound closure experiments. AMS Classifications: 35A01; 35B09; 35B40; 35K57; 92C17 PMID:23289870

  16. Characterization of silver nanoparticle-infused tissue adhesive for ophthalmic use

    NASA Astrophysics Data System (ADS)

    Yee, William

    This research examined if the infusion of silver nanoparticles into a 2-octyl cyanoacrylate tissue adhesive alters the antibacterial effectiveness and mechanical properties of the adhesive. Silver nanoparticle size and concentration combinations were varied to determine the effects of these factors. Uniform distribution of the silver nanoparticles was achieved before proceeding to testing. Antibacterial effectiveness of the composite adhesive was determined via the Kirby-Bauer disk diffusion susceptibility test and by CFU counting. Doping the adhesive with silver nanoparticles resulted in an order of magnitude reduction in bacterial growth. The greatest antibacterial effect came from imbuing 10 microg/mL of 4 nm silver nanoparticles into the tissue adhesive. Despite the noticeable reduction of bacterial growth for the doped adhesives, the difference among the varying silver nanoparticle size and concentration combinations was minimal. The breaking strength of the adhesive increased when silver nanoparticles were added. The adhesive strength of the composite adhesive attached to an incised porcine sclera was also greater than the unaltered adhesive. The greatest breaking load and adhesive force was the 10 microg/mL of 10 nm silver nanoparticle-doped adhesive. The increased mechanical strength of the doped adhesive expands the possible applications of treatment on different areas of the body.

  17. Shuttle active thermal control system development testing. Volume 7: Improved radiator coating adhesive tests

    NASA Technical Reports Server (NTRS)

    Reed, M. W.

    1973-01-01

    Silver/Teflon thermal control coatings have been tested on a modular radiator system projected for use on the space shuttle. Seven candidate adhesives have been evaluated in a thermal vacuum test on radiator panels similar to the anticipated flight hardware configuration. Several classes of adhesives based on polyester, silicone, and urethane resin systems were tested. These included contact adhesives, heat cured adhesives, heat and pressure cured adhesives, pressure sensitive adhesives, and two part paint on or spray on adhesives. The coatings attached with four of the adhesives, two silicones and two urethanes, had no changes develop during the thermal vacuum test. The two silicone adhesives, both of which were applied to the silver/Teflon as transfer laminates to form a tape, offered the most promise based on application process and thermal performance. Each of the successful silicone adhesives required a heat and pressure cure to adhere during the cryogenic temperature excursion of the thermal-vacuum test.

  18. Sinter of uniform, predictable, blemish-free nickel plaque for large aerospace nickel cadmium cells

    NASA Technical Reports Server (NTRS)

    Seiger, H. N.

    1975-01-01

    A series of nickel slurry compositions were tested. Important slurry parameters were found to be the nature of the binder, a pore former and the method of mixing. A slow roll mixing which is non-turbulent successfully eliminated entrapped air so that bubbles and pockets were avoided in the sinter. A slurry applicator was developed which enabled an equal quantity of slurry to be applied to both sides of the grid. Sintering in a furnace having a graded atmosphere characteristic, ranging from oxidizing to strongly reducing, improved adhesion of porous sinter to grid and resulted in a uniform welding of nickel particles to each other throughout the plaque. Sintering was carried out in a horizontal furnace having three heating zones and 16 heating control circuits. Tests used for plaque evaluation include (1) appearance, (2) grid location and adhesion, (3) mechanical strength, (4) thickness, (5) weight per unit area, (6) void volume per unit area, (7) surface area and (8) electrical resistance. Plaque material was impregnated using Heliotek proprietary processes and 100 AH cells were fabricated.

  19. 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.

  20. Image Correlation Microscopy for Uniform Illumination

    PubMed Central

    Gaborski, Thomas R.; Sealander, Michael N.; Ehrenberg, Morton; Waugh, Richard E.; McGrath, James L.

    2011-01-01

    Image cross-correlation microscopy (ICM) is a technique that quantifies the motion of fluorescent features in an image by measuring the temporal autocorrelation function decay in a time-lapse image sequence. ICM has traditionally employed laser-scanning microscopes because the technique emerged as an extension of laser-based fluorescence correlation spectroscopy (FCS). In this work, we show that image correlation can also be used to measure fluorescence dynamics in uniform illumination or wide-field imaging systems and we call our new approach uniform illumination image correlation microscopy (UI-ICM). Wide-field microscopy is not only a simpler, less expensive imaging modality, but it offers the capability of greater temporal resolution over laser-scanning systems. In traditional laser-scanning ICM, lateral mobility is calculated from the temporal de-correlation of an image, where the characteristic length is the illuminating laser beam width. In wide-field microscopy, the diffusion length is defined by the feature size using the spatial autocorrelation function (SACF). Correlation function decay in time occurs as an object diffuses from its original position. We show that theoretical and simulated comparisons between Gaussian and uniform features indicate the temporal autocorrelation function (TACF) depends strongly on particle size and not particle shape. In this report, we establish the relationships between the SACF feature size, TACF characteristic time and the diffusion coefficient for UI-ICM using analytical, Monte-Carlo and experimental validation with particle tracking algorithms. Additionally, we demonstrate UI-ICM analysis of adhesion molecule domain aggregation and diffusion on the surface of human neutrophils. PMID:20055917

  1. Vertical uniformity of cells and nuclei in epithelial monolayers.

    PubMed

    Neelam, Srujana; Hayes, Peter Robert; Zhang, Qiao; Dickinson, Richard B; Lele, Tanmay P

    2016-01-22

    Morphological variability in cytoskeletal organization, organelle position and cell boundaries is a common feature of cultured cells. Remarkable uniformity and reproducibility in structure can be accomplished by providing cells with defined geometric cues. Cells in tissues can also self-organize in the absence of directing extracellular cues; however the mechanical principles for such self-organization are not understood. We report that unlike horizontal shapes, the vertical shapes of the cell and nucleus in the z-dimension are uniform in cells in cultured monolayers compared to isolated cells. Apical surfaces of cells and their nuclei in monolayers were flat and heights were uniform. In contrast, isolated cells, or cells with disrupted cell-cell adhesions had nuclei with curved apical surfaces and variable heights. Isolated cells cultured within micron-sized square wells displayed flat cell and nuclear shapes similar to cells in monolayers. Local disruption of nuclear-cytoskeletal linkages resulted in spatial variation in vertical uniformity. These results suggest that competition between cell-cell pulling forces that expand and shorten the vertical cell cross-section, thereby widening and flattening the nucleus, and the resistance of the nucleus to further flattening results in uniform cell and nuclear cross-sections. Our results reveal the mechanical principles of self-organized vertical uniformity in cell monolayers.

  2. Vertical uniformity of cells and nuclei in epithelial monolayers

    PubMed Central

    Neelam, Srujana; Hayes, Peter Robert; Zhang, Qiao; Dickinson, Richard B.; Lele, Tanmay P.

    2016-01-01

    Morphological variability in cytoskeletal organization, organelle position and cell boundaries is a common feature of cultured cells. Remarkable uniformity and reproducibility in structure can be accomplished by providing cells with defined geometric cues. Cells in tissues can also self-organize in the absence of directing extracellular cues; however the mechanical principles for such self-organization are not understood. We report that unlike horizontal shapes, the vertical shapes of the cell and nucleus in the z-dimension are uniform in cells in cultured monolayers compared to isolated cells. Apical surfaces of cells and their nuclei in monolayers were flat and heights were uniform. In contrast, isolated cells, or cells with disrupted cell-cell adhesions had nuclei with curved apical surfaces and variable heights. Isolated cells cultured within micron-sized square wells displayed flat cell and nuclear shapes similar to cells in monolayers. Local disruption of nuclear-cytoskeletal linkages resulted in spatial variation in vertical uniformity. These results suggest that competition between cell-cell pulling forces that expand and shorten the vertical cell cross-section, thereby widening and flattening the nucleus, and the resistance of the nucleus to further flattening results in uniform cell and nuclear cross-sections. Our results reveal the mechanical principles of self-organized vertical uniformity in cell monolayers. PMID:26795751

  3. 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

  4. 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

  5. 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.

  6. 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

  7. [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.

  8. 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.

  9. 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

  10. Carbon nanotube based gecko inspired self-cleaning adhesives

    NASA Astrophysics Data System (ADS)

    Sethi, Sunny; Ge, Liehui; Ajayan, Pulickel; Ali, Dhinojwala

    2008-03-01

    Wall climbing organisms like geckos have unique ability to attach to different surfaces without use of any viscoelastic material. The hairy structure found in gecko feet allows them to obtain intimate contact over a large area thus allowing then to adhere using van der Waals interactions. Not only high adhesion, the geometry of the hairs makes gecko feet self cleaning, thus allowing them to walk continuously without worrying about loosing adhesive strength. Such properties if mimicked synthetically could form basis of a new class of materials, which, unlike conventional adhesives would show two contradictory properties, self cleaning and high adhesion. Such materials would form essential component of applications like wall climbing robot. We tried to synthesize such material using micropatterened vertically aligned carbon nanotubes. When dealing with large areas, probability of defects in the structure increase, forming patterns instead of using uniform film of carbon nanotubes helps to inhibit crack propagation, thus gives much higher adhesive strength than a uniform film. When carbon nanotube patterns with optimized aspect ratio are used, both high adhesion and self cleaning properties are observed.

  11. 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.

  12. Perceptual uniformity of commonly used color spaces

    NASA Astrophysics Data System (ADS)

    Avanaki, Ali; Espig, Kathryn; Kimpe, Tom; Xthona, Albert; Marchessoux, Cedric; Rostang, Johan; Piepers, Bastian

    2014-03-01

    Use of color images in medical imaging has increased significantly the last few years. Color information is essential for applications such as ophthalmology, dermatology and clinical photography. Use of color at least brings benefits for other applications such as endoscopy, laparoscopy and digital pathology. Remarkably, as of today, there is no agreed standard on how color information needs to be visualized for medical applications. This lack of standardization results in large variability of how color images are visualized and it makes quality assurance a challenge. For this reason FDA and ICC recently organized a joint summit on color in medical imaging (CMI). At this summit, one of the suggestions was that modalities such as digital pathology could benefit from using a perceptually uniform color space (T. Kimpe, "Color Behavior of Medical Displays," CMI presentation, May 2013). Perceptually uniform spaces have already been used for many years in the radiology community where the DICOM GSDF standard provides linearity in luminance but not in color behavior. In this paper we quantify perceptual uniformity, using CIE's ΔE2000 as a color distance metric, of several color spaces that are typically used for medical applications. We applied our method to theoretical color spaces Gamma 1.8, 2.0, & 2.2, standard sRGB, and DICOM (correction LUT for gray applied to all primaries). In addition, we also measured color spaces (i.e., native behavior) of a high-end medical display (Barco Coronis Fusion 6MP DL, MDCC-6130), and a consumer display (Dell 1907FP). Our results indicate that sRGB & the native color space on the Barco Coronis Fusion exhibit the least non-uniformity within their group. However, the remaining degree of perceptual non-uniformity is still significant and there is room for improvement.

  13. Fast-Acting Rubber-To-Coated-Aluminum Adhesive

    NASA Technical Reports Server (NTRS)

    Comer, Dawn A.; Novak, Howard; Vazquez, Mark

    1991-01-01

    Cyanoacrylate adhesive used to join rubber to coated aluminum easier to apply and more effective. One-part material applied in single coat to aluminum treated previously with epoxy primer and top coat. Parts mated as soon as adhesive applied; no drying necessary. Sets in 5 minutes. Optionally, accelerator brushed onto aluminum to reduce setting time to 30 seconds. Clamping parts together unnecessary. Adhesive comes in four formulations, all based on ethyl cyanoacrylate with various amounts of ethylene copolymer rubber, poly(methyl methacrylate), silicon dioxide, hydroquinone, and phthalic anhydride.

  14. 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.

  15. School Uniforms: Esprit de Corps.

    ERIC Educational Resources Information Center

    Ryan, Rosemary P.; Ryan, Thomas E.

    1998-01-01

    The benefits of school uniforms far outweigh their short-term costs. School uniforms not only keep students safe, but they increase their self-esteem, promote a more positive attitude toward school, lead to improved student behavior, and help blur social-class distinctions. Students are allowed to wear their own political or religious messages,…

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. Adhesion of polysilicon microbeams in controlled humidity ambients

    SciTech Connect

    Boer, M.P. de; Clews, P.J.; Smith, B.K.; Michalske, T.A.

    1998-04-01

    The authors characterize in-situ the adhesion of surface micromachined polysilicon beams subject to controlled humidity ambients. Beams were freed by supercritical CO{sub 2} drying. Consistent adhesion results were obtained using a post-treatment in an oxygen plasma which rendered the microbeams uniformly hydrophilic. Individual beam deformations were measured by optical interferometry after equilibration at a given relative humidity (RH). Validation of each adhesion measurement was accomplished by comparing the deformations with elasticity theory. The data indicates that adhesion increases exponentially with RH from 30% to 95%, with values from 1 mJ/m{sup 2} to 50 mJ/m{sup 2}. Using the Kelvin equation, the authors show that the data should be independent of RH if a smooth interface is considered. By modeling a rough interface consistent with atomic force microscopy (AFM) data, the exponential trend is satisfactorily explained.

  5. 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

  6. 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.

  7. Urethane/Silicone Adhesives for Bonding Flexing Metal Parts

    NASA Technical Reports Server (NTRS)

    Edwards, Paul D.

    2004-01-01

    adhesive is supplied in a two-part form, comprising a resin and a hardener that must be mixed. The resulting urethane adhesive has a working time of 3 to 5 minutes. To prepare the urethane/silicone blend, one must quickly add the silicone to the urethane adhesive and mix it in thoroughly within the working time of the urethane. Once the urethane/silicone blend has been mixed and applied to the bond surfaces, it takes about 2 hours for the adhesive to cure under pressure. However, it takes about 24 hours for the adhesive to reach full strength.

  8. Metastable states and activated dynamics in thin-film adhesion to patterned surfaces.

    PubMed

    Lindström, Stefan B; Johansson, Lars; Karlsson, Nils R

    2014-06-01

    We consider adhesion due to London-van der Waals attraction between a thin film and a patterned surface with nanometer asperities. Depending on the surface topography and the stiffness of the film, three regimes of adhesion are identified: complete contact adhesion, partial contact adhesion, and glassy adhesion. For complete contact adhesion, the film conforms to the undulations of the surface, whereas for partial contact and glassy adhesion, the adhesive interface breaks down into microscopic areas of contact. When a film in the glassy regime is peeled off the surface, metastable states develop at which the crack front becomes arrested, analogously to the frustrated motion of the three-phase contact line across a heterogeneous surface. For this glassy regime, we use transition state theory to model the thermally activated progression of the crack front. This theoretical treatment suggests that the rate of the adhesive failure increases exponentially with the applied force.

  9. The Freeform Reflector for Uniform Rectangular Illumination

    NASA Astrophysics Data System (ADS)

    Ding, Yi; Gu, Pei-Fu; Zheng, Zhen-Rong

    2007-12-01

    Energy from the source was rearranged through reflection by a freeform reflector, in order to get uniform rectangular illumination. The numerical results of partial differential equation sets were investigated to obtain the freeform reflector and these equations were obtained upon the determination of the characters of source and the desired illumination. As an example, a light emitting diode (LED) with a Lambertian light-emitting surface of 1 × 1 mm2 and a viewing angle of 120° was applied as the source, and the target plane was a 4:3 rectangle with uniform illumination. The projective length of the reflector on x-axis is about 23 mm, and on y-axis is about 21 mm. Thus the illumination system is very compact.

  10. The Uniformly Accelerated Reference Frame

    ERIC Educational Resources Information Center

    Hamilton, J. Dwayne

    1978-01-01

    The observations that would be made by a uniformly accelerated observer, including the observer's event horizon, the variation of clock rates with position, and the effects of following a freely falling object are considered in detail. (SL)

  11. 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

  12. 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.

  13. Neutrophil adhesion and chemotaxis depend on substrate mechanics

    NASA Astrophysics Data System (ADS)

    Jannat, Risat A.; Robbins, Gregory P.; Ricart, Brendon G.; Dembo, Micah; Hammer, Daniel A.

    2010-05-01

    Neutrophil adhesion to the vasculature and chemotaxis within tissues play critical roles in the inflammatory response to injury and pathogens. Unregulated neutrophil activity has been implicated in the progression of numerous chronic and acute diseases such as rheumatoid arthritis, asthma and sepsis. Cell migration of anchorage-dependent cells is known to depend on both chemical and mechanical interactions. Although neutrophil responses to chemical cues have been well characterized, little is known about the effect of underlying tissue mechanics on neutrophil adhesion and migration. To address this question, we quantified neutrophil migration and traction stresses on compliant hydrogel substrates with varying elasticity in a micromachined gradient chamber in which we could apply either a uniform concentration or a precise gradient of the bacterial chemoattractant fMLP. Neutrophils spread more extensively on substrates of greater stiffness. In addition, increasing the stiffness of the substrate leads to a significant increase in the chemotactic index for each fMLP gradient tested. As the substrate becomes stiffer, neutrophils generate higher traction forces without significant changes in cell speed. These forces are often displayed in pairs and focused in the uropod. Increases in the mean fMLP concentration beyond the KD of the receptor lead to a decrease in chemotactic index on all surfaces. Blocking with an antibody against β2-integrins leads to a significant reduction, but not an elimination, of directed motility on stiff materials, but no change in motility on soft materials, suggesting neutrophils can display both integrin-dependent and integrin-independent motility. These findings are critical for understanding how neutrophil migration may change in different mechanical environments in vivo and can be used to guide the design of migration inhibitors that more efficiently target inflammation.

  14. 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

  15. Contribution from pressure-sensitive adhesives

    NASA Astrophysics Data System (ADS)

    Cunningham, Gilbert

    1996-03-01

    containers where the content can be easily seen without interference and where wording or symbols can be read through the container. You see this increasingly with pharmaceuticals, cosmetics and toiletries, even bottled beer. Achieving transparency is one thing but this property must be combined with all the physical properties required of the pressure sensitive adhesive. First there is the question of permanence, re-positionability and removability and the degree to which these features are required. Secondly many complications arise from the range of materials to which the adhesive must be anchored and the range to which it will be applied and must bond. Obviously these surfaces vary from those with the highest surface energy (polycarbonate for example) to those apolar surfaces engineered for minimum attraction (PTFE -- 'Teflon' for example).

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Passively stuck: death does not affect gecko adhesion strength.

    PubMed

    Stewart, William J; Higham, Timothy E

    2014-12-01

    Many geckos use adhesive toe pads on the bottom of their digits to attach to surfaces with remarkable strength. Although gecko adhesion has been studied for hundreds of years, gaps exist in our understanding at the whole-animal level. It remains unclear whether the strength and maintenance of adhesion are determined by the animal or are passively intrinsic to the system. Here we show, for the first time, that strong adhesion is produced passively at the whole-animal level. Experiments on both live and recently euthanized tokay geckos (Gekko gecko) revealed that death does not affect the dynamic adhesive force or motion of a gecko foot when pulled along a vertical surface. Using a novel device that applied repeatable and steady-increasing pulling forces to the foot in shear, we found that the adhesive force was similarly high and variable when the animal was alive (mean ± s.d. = 5.4 ± 1.7 N) and within 30 min after death (5.4 ± 2.1 N). However, kinematic analyses showed that live geckos are able to control the degree of toe pad engagement and can rapidly stop strong adhesion by hyperextending the toes. This study offers the first assessment of whole-animal adhesive force under extremely controlled conditions. Our findings reveal that dead geckos maintain the ability to adhere with the same force as living animals, disproving that strong adhesion requires active control.

  5. Passively stuck: death does not affect gecko adhesion strength

    PubMed Central

    Stewart, William J.; Higham, Timothy E.

    2014-01-01

    Many geckos use adhesive toe pads on the bottom of their digits to attach to surfaces with remarkable strength. Although gecko adhesion has been studied for hundreds of years, gaps exist in our understanding at the whole-animal level. It remains unclear whether the strength and maintenance of adhesion are determined by the animal or are passively intrinsic to the system. Here we show, for the first time, that strong adhesion is produced passively at the whole-animal level. Experiments on both live and recently euthanized tokay geckos (Gekko gecko) revealed that death does not affect the dynamic adhesive force or motion of a gecko foot when pulled along a vertical surface. Using a novel device that applied repeatable and steady-increasing pulling forces to the foot in shear, we found that the adhesive force was similarly high and variable when the animal was alive (mean ± s.d. = 5.4 ± 1.7 N) and within 30 min after death (5.4 ± 2.1 N). However, kinematic analyses showed that live geckos are able to control the degree of toe pad engagement and can rapidly stop strong adhesion by hyperextending the toes. This study offers the first assessment of whole-animal adhesive force under extremely controlled conditions. Our findings reveal that dead geckos maintain the ability to adhere with the same force as living animals, disproving that strong adhesion requires active control. PMID:25472940

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. Processing of materials for uniform field emission

    DOEpatents

    Pam, L.S.; Felter, T.E.; Talin, A.; Ohlberg, D.; Fox, C.; Han, S.

    1999-01-12

    This method produces a field emitter material having a uniform electron emitting surface and a low turn-on voltage. Field emitter materials having uniform electron emitting surfaces as large as 1 square meter and turn-on voltages as low as 16V/{micro}m can be produced from films of electron emitting materials such as polycrystalline diamond, diamond-like carbon, graphite and amorphous carbon by the method of the present invention. The process involves conditioning the surface of a field emitter material by applying an electric field to the surface, preferably by scanning the surface of the field emitter material with an electrode maintained at a fixed distance of at least 3 {micro}m above the surface of the field emitter material and at a voltage of at least 500V. In order to enhance the uniformity of electron emission the step of conditioning can be preceded by ion implanting carbon, nitrogen, argon, oxygen or hydrogen into the surface layers of the field emitter material. 2 figs.

  13. Instrumentation For Detector Spectral / Spatial Uniformity Measurements

    NASA Astrophysics Data System (ADS)

    Craft, Ronald W.; Bronson, Robert M.

    1989-09-01

    The information presented in this report describes an instrument which is used for precision measurements of detector spectral response and spatial response. Emphasis will be placed on detector spatial uniformity measurements. To allow spatial uniformity testing at selected wavelengths, an instrument was designed by applying existing spectral response instrumentation technology with the addition of special exit optics, a dual axis motorized positioning table, and supporting software. Supporting components consisted of a computer controlled radiometer and a monochromator with a high intensity light source attached. Spectral response is determined by measuring the wavelength response photosensitivity of a stationary specimen to the irradiance of a calibrated monochromatic light source over the wavelength range of interest at evenly spaced intervals. Data is presented in a pictorial format by graphing the RESPONSE versus the WAVELENGTH. Detector spatial response is determined by measuring the variation in photosensitivity over the surface of the test detector by moving the detector in an X,Y grid at evenly spaced intervals under a small monochromatic spot of light. Several versions of the instrument were built and test results are provided which represent data from the spatial uniformity testing of Ge, PbS, and PbSe detectors. Data acquired is presented as a 3-Dimensional surface map by plotting the RESPONSE versus the X POSITION versus the Y POSITION.

  14. Processing of materials for uniform field emission

    DOEpatents

    Pam, Lawrence S.; Felter, Thomas E.; Talin, Alec; Ohlberg, Douglas; Fox, Ciaran; Han, Sung

    1999-01-01

    This method produces a field emitter material having a uniform electron emitting surface and a low turn-on voltage. Field emitter materials having uniform electron emitting surfaces as large as 1 square meter and turn-on voltages as low as 16V/.mu.m can be produced from films of electron emitting materials such as polycrystalline diamond, diamond-like carbon, graphite and amorphous carbon by the method of the present invention. The process involves conditioning the surface of a field emitter material by applying an electric field to the surface, preferably by scanning the surface of the field emitter material with an electrode maintained at a fixed distance of at least 3 .mu.m above the surface of the field emitter material and at a voltage of at least 500V. In order to enhance the uniformity of electron emission the step of conditioning can be preceeded by ion implanting carbon, nitrogen, argon, oxygen or hydrogen into the surface layers of the field emitter material.

  15. 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.

  16. 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.

  17. 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.

  18. Inverse characterisation of frequency-dependent properties of adhesives

    NASA Astrophysics Data System (ADS)

    Rouleau, Lucie; Deü, Jean-François; Legay, Antoine

    2016-09-01

    Traditional damping treatments are usually applied to the vibrating structure by means of adhesive layers. Environmental parameters, such as frequencies of excitation, may influence the behaviour of the bonding layer and modify the damping efficiency of the treatment. Therefore it is desired to take into account the viscoelastic behaviour of the adhesive layer in the finite element model. The goal of this work is to present a procedure to characterise and model the adhesive layer. To that purpose, an experimental-numerical method for inverse characterisation of the frequency dependent properties of the adhesive layer is applied. The proposed inverse approach is based on a four-parameter fractional derivative model whose parameters are identified by minimising the difference between the simulated and the measured dynamic response of a multi-layered structure assembled by bonding. In the finite element model used for the optimisation, the adhesive layer is modelled by interface finite elements. The influence of the adhesive layer on the efficiency of a damping treatment is evidenced by performing dynamic testing on a sandwich structure with a viscoelastic core, assembled by bonding. The proposed approach is applied to the characterisation of a pressure-sensitive adhesive.

  19. Interactions between uniformly magnetized spheres

    NASA Astrophysics Data System (ADS)

    Edwards, Boyd F.; Riffe, D. M.; Ji, Jeong-Young; Booth, William A.

    2017-02-01

    We use simple symmetry arguments suitable for undergraduate students to demonstrate that the magnetic energy, forces, and torques between two uniformly magnetized spheres are identical to those between two point magnetic dipoles. These arguments exploit the equivalence of the field outside of a uniformly magnetized sphere with that of a point magnetic dipole, and pertain to spheres of arbitrary sizes, positions, and magnetizations. The point dipole/sphere equivalence for magnetic interactions may be useful in teaching and research, where dipolar approximations for uniformly magnetized spheres can now be considered to be exact. The work was originally motivated by interest in the interactions between collections of small neodymium magnetic spheres used as desk toys.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 40 CFR 63.4581 - What definitions apply to this subpart?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... during the adhesive curing reaction, and, as a result, do not evolve from the film during use. These volatile components instead become integral parts of the adhesive through chemical reaction. At least 70... atmosphere. Adhesive, adhesive coating means any chemical substance that is applied for the purpose...

  6. 40 CFR 63.4581 - What definitions apply to this subpart?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... during the adhesive curing reaction, and, as a result, do not evolve from the film during use. These volatile components instead become integral parts of the adhesive through chemical reaction. At least 70... atmosphere. Adhesive, adhesive coating means any chemical substance that is applied for the purpose...

  7. 40 CFR 63.4581 - What definitions apply to this subpart?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... during the adhesive curing reaction, and, as a result, do not evolve from the film during use. These volatile components instead become integral parts of the adhesive through chemical reaction. At least 70.... Adhesive, adhesive coating means any chemical substance that is applied for the purpose of bonding...

  8. School Uniforms: Guidelines for Principals.

    ERIC Educational Resources Information Center

    Essex, Nathan L.

    2001-01-01

    Principals desiring to develop a school-uniform policy should involve parents, teachers, community leaders, and student representatives; beware restrictions on religious and political expression; provide flexibility and assistance for low-income families; implement a pilot program; align the policy with school-safety issues; and consider legal…

  9. Uniform peanut performance test 2015

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Uniform Peanut Performance Tests (UPPT) are designed to evaluate the commercial potential of advanced breeding peanut lines not formally released. The tests are performed in ten locations across the peanut production belt. In this study, 2 controls and 13 entries were evaluated at 9 locations....

  10. Uniform peanut performance test 2013

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Uniform Peanut Performance Tests (UPPT) are designed to evaluate the commercial potential of advanced breeding peanut lines not formally released. The tests are performed in ten locations across the peanut production belt. In this study, 2 controls and 13 entries were evaluated at 9 locations....

  11. Uniform Peanut Performance Tests 2012

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Uniform Peanut Performance Tests (UPPT) were established in 1973 through an informal arrangement among cooperating scientists involving seven major peanut-producing states. In 1995, plant material transfer agreements were also accepted among all cooperators in the UPPT. The year 2012 completed...

  12. Trying Uniforms on for Size.

    ERIC Educational Resources Information Center

    Paliokas, Kathleen L.; And Others

    1996-01-01

    Public school uniforms are a recent development. Legal trends suggest that the courts are willing to defer to school authorities regarding dress codes--provided a clear link is established between the dress regulations and furtherance of the educational mission. Lists a range of options for a dress-code policy and how each of the available options…

  13. Alternating-current electrophoretic adhesion of biodegradable hydrogel utilizing intermediate polymers.

    PubMed

    Asoh, Taka-Aki; Kawai, Wataru; Kikuchi, Akihiko

    2014-11-01

    The adhesion of anionic charged biodegradable hydrogels each other utilizing oppositely charged water-soluble polymers as a binder has been achieved by applying alternating-current (AC) electric fields. The two gelatin based dextran sulfate gels (DS gels) were molecularly sutured together by AC electrophoretic adhesion when cationic charged quaternary ammonium chitosan (TMC) was applied between and held in contact with the two DS gels. The adhesive strength of the gels increased with increasing periodicity when a square wave was applied. Hydrogel constructs composed of DS microgels were prepared simply by AC electrophoretic adhesion utilizing intermediate TMC.

  14. Natural tissue microenvironmental conditions modulate adhesive material performance.

    PubMed

    Oliva, Nuria; Shitreet, Sagi; Abraham, Eytan; Stanley, Butch; Edelman, Elazer R; Artzi, Natalie

    2012-10-30

    We designed and optimized tissue-responsive adhesive materials by matching material and tissue properties. A two-component material based on dextran aldehyde and dendrimer amine provides a cohesive gel through aldehyde-amine cross-linking and an adhesive interface created by a dextran aldehyde-selective reaction with tissue amines. By altering aldehyde-amine chemistry, we examined how variations in tissue surfaces (serosal amine density in the duodenum, jejunum, and ileum) affect interactions with adhesive materials of varied compositions (aldehyde content). Interestingly, the same adhesive formulation reacts differentially with the three regions of the small intestine as a result of variation in the tissue amine density along the intestinal tract, affecting the tissue-material interfacial morphology, adhesion strength, and adhesive mechanical properties. Whereas tissues provide chemical anchors for interaction with materials, we were able to tune the adhesion strength for each section of the small intestine tissue by altering the adhesive formulation using a two-component material with flexible variables aimed at controlling the aldehyde/amine ratio. This tissue-specific approach should be applied to the broad spectrum of biomaterials, taking into account specific microenvironmental conditions in material design.

  15. Quantitative adhesion characterization of antireflective coatings in multijunction photovoltaics

    SciTech Connect

    Brock, Ryan; Rewari, Raunaq; Novoa, Fernando D.; Hebert, Peter; Ermer, James; Miller, David C.; Dauskardt, Reinhold H.

    2016-08-01

    We discuss the development of a new composite dual cantilever beam (cDCB) thin-film adhesion testing method, which enables the quantitative measurement of adhesion on the thin and fragile substrates used in multijunction photovoltaics. In particular, we address the adhesion of several 2- and 3-layer antireflective coating systems on multijunction cells. By varying interface chemistry and morphology through processing, we demonstrate the marked 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 demonstrate that even with germanium substrates that fracture relatively easily, quantitative measurements of adhesion can 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.

  16. Measurement of thin film adhesion by single cantilever beam method equipped with adjustable jig

    NASA Astrophysics Data System (ADS)

    Shin, Dong-Kil; Lee, Jung-Ju; Hawong, Jai-Sug

    2015-03-01

    A new method to measure the tensile adhesion of thin film was proposed. A single cantilever beam method was used and an efficient adjustable jig was designed to minimize errors induced by misalignment of specimen. Applied load and displacement were recorded by data acquisition system. The dimensions of the specimen and conditions of test were preexamined by finite element analysis. Developed method was applied to measure the adhesion of thin film adhesive. Test results were independent of initial deviation of specimen alignment and showed consistent value with respect to crack length. Compared with shear test method, it was shown that the shear adhesion included the effect of thickness of adhesive, however, tensile adhesion was independent of the thickness of adhesive.

  17. [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.

  18. 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.

  19. 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.

  20. Adhesive and morphological characteristics of surface chemically modified polytetrafluoroethylene films

    NASA Astrophysics Data System (ADS)

    Hopp, B.; Kresz, N.; Kokavecz, J.; Smausz, T.; Schieferdecker, H.; Döring, A.; Marti, O.; Bor, Z.

    2004-01-01

    In the present paper, we report an experimental determination of adhesive and topographic characteristics of chemically modified surface of polytetrafluoroethylene (PTFE) films. The surface chemistry was modified by ArF excimer laser irradiation in presence of triethylene-tetramine photoreagent. The applied laser fluence was varied in the range of 0.4-9 mJ/cm 2, and the number of laser pulses incident on the same area was 1500. To detect the changes in the adhesive features of the treated Teflon samples, we measured receding contact angle for distilled water and adhesion strength, respectively. It was found that the receding contact angle decreased from 96° to 30-37° and the adhesion strength of two-component epoxy glue to the treated sample surface increased from 0.03 to 9 MPa in the applied laser fluence range. Additionally, it was demonstrated that the adhesion of human cells to the modified Teflon samples is far better than to the untreated ones. The contact mode and pulsed force mode atomic force microscopic investigations of the treated samples demonstrated that the measured effective contact area of the irradiated films does not differ significantly from that of the original films, but the derived adhesion force is stronger on the modified samples than on the untreated ones. Hence, the increased adhesion of the treated Teflon films is caused by the higher surface energy.

  1. Do adhesive systems leave resin coats on the surfaces of the metal matrix bands? An adhesive remnant characterization.

    PubMed

    Arhun, Neslihan; Cehreli, Sevi Burcak

    2013-01-01

    Reestablishing proximal contacts with composite resins may prove challenging since the applied adhesives may lead to resin coating that produces additional thickness. The aim of this study was to investigate the surface of metal matrix bands after application of adhesive systems and blowing or wiping off the adhesive before polymerization. Seventeen groups of matrix bands were prepared. The remnant particles were characterized by energy dispersive spectrum and scanning electron microscopy. Total etch and two-step self-etch adhesives did not leave any resin residues by wiping and blowing off. All-in-one adhesive revealed resin residues despite wiping off. Prime and Bond NT did not leave any remnant with compomer. Clinicians must be made aware of the consequences of possible adhesive remnants on matrix bands that may lead to a defective definitive restoration. The adhesive resin used for Class II restorations may leave resin coats on metal matrix bands after polymerization, resulting in additional thickness on the metal matrix bands and poor quality of the proximal surface of the definitive restoration when the adhesive system is incorporated in the restoration.

  2. Adhesion and Thin-Film Module Reliability: Preprint

    SciTech Connect

    McMahon, T. J.; Jorgensen, G. J.

    2006-05-01

    Among the infrequently measured but essential properties for thin-film (T-F) module reliability are the interlayer adhesion and cohesion within a layer. These can be cell contact layers to glass, contact layers to the semiconductor, encapsulant to cell, glass, or backsheet, etc. We use an Instron mechanical testing unit to measure peel strengths at 90{sup o} or 180{sup o} and, in some cases, a scratch and tape pull test to evaluate inter-cell layer adhesion strengths. We present peel strength data for test specimens laminated from the three T-F technologies, before and after damp heat, and in one instance at elevated temperatures. On laminated T-F cell samples, failure can occur uniformly at any one of the many interfaces, or non-uniformly across the peel area at more than one interface. Some peel strengths are << 1 N/mm. This is far below the normal Instron mechanical testing unit Instron mechanical testing unit; glass interface values of >10 N/mm. We measure a wide range of adhesion strengths and suggest that adhesion measured under higher temperature and relative humidity conditions is more relevant for module reliability.

  3. 46 CFR 310.11 - Cadet uniforms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... for State, Territorial or Regional Maritime Academies and Colleges § 310.11 Cadet uniforms. Cadet uniforms shall be supplied at the school in accordance with the uniform regulations of the School. Those... 46 Shipping 8 2010-10-01 2010-10-01 false Cadet uniforms. 310.11 Section 310.11 Shipping...

  4. 46 CFR 310.11 - Cadet uniforms.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... for State, Territorial or Regional Maritime Academies and Colleges § 310.11 Cadet uniforms. Cadet uniforms shall be supplied at the school in accordance with the uniform regulations of the School. Those... 46 Shipping 8 2011-10-01 2011-10-01 false Cadet uniforms. 310.11 Section 310.11 Shipping...

  5. 46 CFR 310.11 - Cadet uniforms.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... for State, Territorial or Regional Maritime Academies and Colleges § 310.11 Cadet uniforms. Cadet uniforms shall be supplied at the school in accordance with the uniform regulations of the School. Those... 46 Shipping 8 2013-10-01 2013-10-01 false Cadet uniforms. 310.11 Section 310.11 Shipping...

  6. 46 CFR 310.11 - Cadet uniforms.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... for State, Territorial or Regional Maritime Academies and Colleges § 310.11 Cadet uniforms. Cadet uniforms shall be supplied at the school in accordance with the uniform regulations of the School. Those... 46 Shipping 8 2014-10-01 2014-10-01 false Cadet uniforms. 310.11 Section 310.11 Shipping...

  7. 46 CFR 310.11 - Cadet uniforms.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... for State, Territorial or Regional Maritime Academies and Colleges § 310.11 Cadet uniforms. Cadet uniforms shall be supplied at the school in accordance with the uniform regulations of the School. Those... 46 Shipping 8 2012-10-01 2012-10-01 false Cadet uniforms. 310.11 Section 310.11 Shipping...

  8. Small Arms: Treated Uniforms for Personal Protection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Permethrin-treatment of field-worn U.S. Military uniforms has been standard practice since 1991. The uniform fabric composition has changed significantly from 100% cotton to 50:50 nylon:cotton Battle Dress Uniforms (BDUs), to 50:50 nylon:cotton Army Combat Uniforms (ACUs) with wrinkle-free finish, a...

  9. 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.

  10. 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)

  11. Development of a Nonchromate Structural Adhesive Bond Primer

    DTIC Science & Technology

    2014-11-01

    Prevent corrosion of base metal • Applied to porous anodized surface • Overcoated with non-inhibited epoxy adhesive • High adhesive bond strength...primers •Long-running surveillance of chromate-free alternatives by UTC companies shows weak corrosion inhibition • (A) strontium chromate...solubility of multiple inhibitors 7705 Al / EcoTuff™ After corrosion test Bright deposits: 50 wt% W + Zn mixed oxide 3M Commercial EW5000AS(P) 3M Lab

  12. Reactor for making uniform capsules

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Anikumar, Amrutur V. (Inventor); Lacik, Igor (Inventor)

    1999-01-01

    The present invention provides a novel reactor for making capsules with uniform membrane. The reactor includes a source for providing a continuous flow of a first liquid through the reactor; a source for delivering a steady stream of drops of a second liquid to the entrance of the reactor; a main tube portion having at least one loop, and an exit opening, where the exit opening is at a height substantially equal to the entrance. In addition, a method for using the novel reactor is provided. This method involves providing a continuous stream of a first liquid; introducing uniformly-sized drops of the second liquid into the stream of the first liquid; allowing the drops to react in the stream for a pre-determined period of time; and collecting the capsules.

  13. Method for uniformly bending conduits

    DOEpatents

    Dekanich, S.J.

    1984-04-27

    The present invention is directed to a method for bending metal tubing through various radii while maintaining uniform cross section of the tubing. The present invention is practical by filling the tubing to a sufficient level with water, freezing the water to ice and bending the ice-filled tubing in a cooled die to the desired radius. The use of the ice as a filler material provides uniform cross-sectional bends of the tubing and upon removal of the ice provides an uncontaminated interior of the tubing which will enable it to be used in its intended application without encountering residual contaminants in the tubing due to the presence of the filler material.

  14. Uniform batch processing using microwaves

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin B. (Inventor); Jackson, Henry W. (Inventor)

    2000-01-01

    A microwave oven and microwave heating method generates microwaves within a cavity in a predetermined mode such that there is a known region of uniform microwave field. Samples placed in the region will then be heated in a relatively identical manner. Where perturbations induced by the samples are significant, samples are arranged in a symmetrical distribution so that the cumulative perturbation at each sample location is the same.

  15. 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

  16. Adhesive-Bonded Composite Joint Analysis with Delaminated Surface Ply Using Strain-Energy Release Rate

    NASA Technical Reports Server (NTRS)

    Chadegani, Alireza; Yang, Chihdar; Smeltzer, Stanley S. III

    2012-01-01

    This paper presents an analytical model to determine the strain energy release rate due to an interlaminar crack of the surface ply in adhesively bonded composite joints subjected to axial tension. Single-lap shear-joint standard test specimen geometry with thick bondline is followed for model development. The field equations are formulated by using the first-order shear-deformation theory in laminated plates together with kinematics relations and force equilibrium conditions. The stress distributions for the adherends and adhesive are determined after the appropriate boundary and loading conditions are applied and the equations for the field displacements are solved. The system of second-order differential equations is solved to using the symbolic computation tool Maple 9.52 to provide displacements fields. The equivalent forces at the tip of the prescribed interlaminar crack are obtained based on interlaminar stress distributions. The strain energy release rate of the crack is then determined by using the crack closure method. Finite element analyses using the J integral as well as the crack closure method are performed to verify the developed analytical model. It has been shown that the results using the analytical method correlate well with the results from the finite element analyses. An attempt is made to predict the failure loads of the joints based on limited test data from the literature. The effectiveness of the inclusion of bondline thickness is justified when compared with the results obtained from the previous model in which a thin bondline and uniform adhesive stresses through the bondline thickness are assumed.

  17. 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.

  18. 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)

  19. 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

  20. Quantitative studies of endothelial cell adhesion. Directional remodeling of focal adhesion sites in response to flow forces.

    PubMed Central

    Davies, P F; Robotewskyj, A; Griem, M L

    1994-01-01

    Focal adhesion sites were observed in cultured endothelial cells by tandem scanning confocal microscopy and digitized image analysis, techniques that provide real-time images of adhesion site area and topography in living cells. Image subtraction demonstrated that in the presence of unidirectional steady laminar flow (shear stress [tau] = 10 dyn/cm2) a substantial fraction of focal adhesion sites remodeled in the direction of flow. In contrast, focal adhesions of control (no flow) cells remodeled without preferred direction. In confluent monolayers subjected to shear stresses of 10 dyn/cm2, cells began to realign in the direction of flow after 7-9 h. This was accompanied by redistribution of intracellular stress fibers, alignment of individual focal adhesion sites, and the coalescence of smaller sites resulting in fewer, but larger, focal adhesions per cell. Cell adhesion, repeatedly calculated in the same cells as a function of the areas of focal contact and the separation distances between membrane and substratum, varied by < 10% during both short (30 min), or prolonged (< or = 24 h), periods of exposure to flow. Consistent with these measurements, the gains and losses of focal adhesion area as each site remodeled were approximately equivalent. When the glass substratum was coated with gelatin, rates of remodeling were inhibited by 47% during flow (tau = 10 dyn/cm2). These studies: (a) reveal the dynamic nature of focal adhesion; (b) demonstrate that these sites at the ablumenal endothelial membrane are both acutely and chronically responsive to frictional shear stress forces applied to the opposite (lumenal) cell surface; and (c) suggest that components of the focal adhesion complex may be mechanically responsive elements coupled to the cytoskeleton. Images PMID:8182135

  1. Adhesions: pathogenesis and prevention-panel discussion and summary.

    PubMed

    Holmdahl, L; Risberg, B; Beck, D E; Burns, J W; Chegini, N; diZerega, G S; Ellis, H

    1997-01-01

    adhesion formation and prevention abounds in a variety of avenues of investigation, including: 1) identification on a molecular level of the components involved in adhesiogenesis and their interactions; 2) clarification of the role of fibrin and fibrinolysis in adhesion formation; 3) standardization of design in preclinical and clinical studies of adhesion formation and prevention; 4) delineation of the relationship between adhesion formation and adhesive complications; and 5) elucidation of efficient, site-specific methods of prophylactic drug delivery. Currently, it seems logical to focus preventive research on development of barriers, fibrinolytic drugs, and selected agents such as phospholipids. The major strategies for adhesion prevention or reduction are adjusting surgical practice and applying adjuvants. Surgeons should adjust their major practices by: 1) becoming aware of the potential adhesive complications of a procedure; 2) minimizing the invasiveness of surgery; and 3) minimizing surgical trauma, ischemia, exposure to intestinal contents, introduction of foreign material into the body, and the use of talc- or starch-containing gloves. Available adjuvants include a newly developed by hyaluronic acid-phosphate-buffered saline solution applied intraoperatively to protect peritoneal surfaces from indirect surgical trauma and three mechanical barriers. One of these, a bioresorbable membrane consisting of hyaluronic acid and carboxymethylcellulose, has demonstrated efficacy and safety in both general and gynecological surgery. The other two barriers, one made of expanded polytetrafluoroethylene and one developed from oxidized regenerated cellulose, are indicated only for use in gynecological surgery.

  2. 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.

  3. Influence of colloidal silicon dioxide on gel strength, robustness, and adhesive properties of diclofenac gel formulation for topical application.

    PubMed

    Lu, Zheng; Fassihi, Reza

    2015-06-01

    The objective of this study is to identify the extent of stiffness, adhesiveness, and thixotropic character of a three-dimensional gel network of a 1% diclofenac sodium topical gel formulation in the presence and absence of colloidal silicon dioxide (CSD) and assess its ease of application and adhesiveness using both objective and subjective analysis. The 1% diclofenac gel was mixed with different amounts of CSD (e.g., 0.5, 1, 2, 3, and 5% w/w) and allowed to equilibrate prior to testing. The texture analyzer in combination with a cone-cap assembly was used to objectively investigate the changes in spreadability and adhesiveness of the gel system before and after addition of CSD. Results indicate that an increase in pliability and adhesiveness at levels ≥2 to ≤5% w/w of CSD dispersed in the gel ensues. For subjective analysis, gels with (2% w/w) CSD and in the absence of CSD were uniformly applied to a 20-cm(2) (5 cm × 4 cm) surface area on the forearms of healthy volunteers and vehicle preferences by the volunteers regarding ease of application, durability on the skin, compliance, and feelings concerning its textural properties were assessed. It appears that changes in the gel formulation with the addition of CSD enhance gel viscosity and bonding to the skin. Results further show that changes in physical and rheological characteristics of gel containing 2% w/w CSD did not significantly change subject preferences for the gel preparations. These findings may help formulators to have additional options to develop more robust and cost-effective formulations.

  4. Prevention of Pseudomonas aeruginosa adhesion by electric currents.

    PubMed

    Shim, Soojin; Hong, Seok Hoon; Tak, Yongsug; Yoon, Jeyong

    2011-02-01

    The process of controlling bacterial adhesion using an electric current deserves attention because of its ease of automation and environmentally friendly nature. This study investigated the role of electric currents (negative, positive, alternating) for preventing adhesion of Pseudomonas aeruginosa and achieving bacterial inactivation. Indium tin oxide (ITO) film was used as a working electrode to observe adhesion and inactivation under electric polarization. Electric current types were classified into negative, positive, and alternating current. The working electrode acted as a cathode or anode by applying a negative or positive current, and an alternating current indicates that the negative current was combined sequentially with the positive current. The numbers of adhered cells were compared under a flow condition, and the in situ behavior of the bacterial cells and the extent of their inactivation were also investigated using time-lapse recording and live/dead staining, respectively. The application of a negative current prevented bacterial adhesion significantly (∼81% at 15.0 μA cm(-2)). The positive current did not significantly inhibit adhesion (<20% at 15.0 μA cm(-2)), compared to the nonpolarized case. The alternating current had a similar effect as the negative current on preventing bacterial adhesion, but it also exhibited bactericidal effects, making it the most suitable method for bacterial adhesion control.

  5. Volatile organic emissions from adhesives with indoor applications

    SciTech Connect

    Girman, J.R.; Hodgson, A.T.; Newton, A.S.; Winkes, A.W.

    1984-02-01

    Studies have shown that volatile organic compounds (VOC) emitted from building materials are a potentially important source of indoor air pollution. In this study, we investigated emissions of VOC from both solvent- and water-based adhesives. Adhesives were applied to an inert substrate and dried for at least a week. VOC were cryogenically trapped and identified by GC-MS or sorbent trapped, solvent extracted, and quantified by GC-FID. Among the compounds emitted by adhesives were toluene, styrene, and a variety of normal, branched, and cyclic alkanes. The measured emission rates ranged from below the limit of detection for some adhesives to a total alkane emission rate of over 700 ..mu..g g/sup -1/h/sup -1/ for a water-based adhesive. A simple, well-mixed tank model was used to assess the potential impacts of the adhesives studied and to demonstrate that adhesives can be significant sources of VOC. 8 references, 1 figure, 2 tables.

  6. Dissecting cell adhesion architecture using advanced imaging techniques

    PubMed Central

    Morton, Penny E

    2011-01-01

    Cell adhesion to extracellular matrix proteins or to other cells is essential for the control of embryonic development, tissue integrity, immune function and wound healing. Adhesions are tightly spatially regulated structures containing over one hundred different proteins that coordinate both dynamics and signaling events at these sites. Extensive biochemical and morphological analysis of adhesion types over the past three decades has greatly improved understanding of individual protein contributions to adhesion signaling and, in some cases, dynamics. However, it is becoming increasingly clear that these diverse macromolecular complexes contain a variety of protein sub-networks, as well as distinct sub-domains that likely play important roles in regulating adhesion behavior. Until recently, resolving these structures, which are often less than a micron in size, was hampered by the limitations of conventional light microscopy. However, recent advances in optical techniques and imaging methods have revealed exciting insight into the intricate control of adhesion structure and assembly. Here we provide an overview of the recent data arising from such studies of cell:matrix and cell:cell contact and an overview of the imaging strategies that have been applied to study the intricacies and hierarchy of proteins within adhesions. PMID:21785274

  7. Effects of MMP inhibitors incorporated within dental adhesives.

    PubMed

    Almahdy, A; Koller, G; Sauro, S; Bartsch, J W; Sherriff, M; Watson, T F; Banerjee, A

    2012-06-01

    Matrix metalloproteinase (MMP) inhibition has been shown to reduce adhesive bond degradation when applied as a pre-conditioner, adding to clinical steps in the placement of adhesives, but their incorporation within dental adhesives has not been fully explored. This study examined the effect of including 2 MMP inhibitors (BB94 and GM6001) within the primers of 3 commercially available adhesives. Fluorometric assay and zymography showed that adhesives with MMP inhibitors had high affinity toward both synthetic fluorogenic FRET peptides (95%) and dentin powder substrates, respectively. The immediate microtensile bond strength was enhanced for 2 types of adhesives following the addition of both inhibitors. However, no changes were detected between the control and the inhibitor groups following 3-month storage. The modified two-step etch-and-rinse and single-step systems showed less Rhodamine B penetration to the "hybrid layer" and to the "adhesive", respectively. The incorporation of BB94 and GM6001 within the primers resulted in the inhibition of dentin MMPs with improved initial bond strength and enhanced sealing ability.

  8. Superior biofunctionality of dental implant fixtures uniformly coated with durable bioglass films by magnetron sputtering.

    PubMed

    Popa, A C; Stan, G E; Enculescu, M; Tanase, C; Tulyaganov, D U; Ferreira, J M F

    2015-11-01

    Bioactive glasses are currently considered the suitable candidates to stir the quest for a new generation of osseous implants with superior biological/functional performance. In congruence with this vision, this contribution aims to introduce a reliable technological recipe for coating fairly complex 3D-shaped implants (e.g. dental screws) with uniform and mechanical resistant bioactive glass films by the radio-frequency magnetron sputtering method. The mechanical reliability of the bioactive glass films applied to real Ti dental implant fixtures has been evaluated by a procedure comprised of "cold" implantation in pig mandibular bone from a dead animal, followed by immediate tension-free extraction tests. The effects of the complex mechanical strains occurring during implantation were analysed by scanning electron microscopy coupled with electron dispersive spectroscopy. Extensive biocompatibility assays (MTS, immunofluorescence, Western blot) revealed that the bioactive glass films stimulated strong cellular adhesion and proliferation of human dental pulp stem cells, without promoting their differentiation. The ability of the implant coatings to conserve a healthy stem cell pool is promising to further endorse the fabrication of new osseointegration implant designs with extended lifetime.

  9. The Allure of Equality: Uniformity in Probabilistic and Statistical Judgment

    ERIC Educational Resources Information Center

    Falk, Ruma; Lann, Avital

    2008-01-01

    Uniformity, that is, equiprobability of all available options is central as a theoretical presupposition and as a computational tool in probability theory. It is justified only when applied to an appropriate sample space. In five studies, we posed diversified problems that called for "unequal" probabilities or weights to be assigned to the given…

  10. Instantly switchable adhesion of bridged fibrillar adhesive via gecko-inspired detachment mechanism and its application to a transportation system.

    PubMed

    Bae, Won-Gyu; Kim, Doogon; Suh, Kahp-Yang

    2013-12-07

    Inspired by the exceptional climbing ability of gecko lizards, artificial fibrillar adhesives have been extensively studied over the last decade both experimentally and theoretically. Therefore, a new leap towards practical uses beyond the academic horizon is timely and highly anticipated. To this end, we present a fibrillar adhesive in the form of bridged micropillars and its application to a transportation system with the detachment mechanism inspired by the climbing behaviour of gecko lizards. The adhesive shows strong normal attachment (~30 N cm(-2)) as well as easy and fast detachment within 0.5 s without involving complex dynamic mechanisms or specific stimulus-responsive materials. The fabrication of the bridged micropillars consists of replica moulding of polydimethylsiloxane (PDMS) micropillars, transfer of the PDMS precursor to the heads of the micropillars, and inverse placement on an inert Teflon-coated surface. Owing to the spontaneous interconnections of low viscosity PDMS precursor, bridged micropillars with a uniform capping nanomembrane (~800 nm thickness) are formed over a large area. Interestingly, macroscopic adhesion in the normal direction can be immediately switched between on and off states by changing the two detachment modes of pulling and peeling, respectively. To prove the potential of the fibrillar adhesive for practical use, an automated transportation system is demonstrated for lifting and releasing a mass of stacked glass slides over 1000 cycles of attachment and detachment.

  11. Designing divertor targets for uniform power load

    NASA Astrophysics Data System (ADS)

    Dekeyser, W.; Reiter, D.; Baelmans, M.

    2015-08-01

    Divertor design for next step fusion reactors heavily relies on 2D edge plasma modeling with codes as e.g. B2-EIRENE. While these codes are typically used in a design-by-analysis approach, in previous work we have shown that divertor design can alternatively be posed as a mathematical optimization problem, and solved very efficiently using adjoint methods adapted from computational aerodynamics. This approach has been applied successfully to divertor target shape design for more uniform power load. In this paper, the concept is further extended to include all contributions to the target power load, with particular focus on radiation. In a simplified test problem, we show the potential benefits of fully including the radiation load in the design cycle as compared to only assessing this load in a post-processing step.

  12. Use of a skin adhesive (octyl-2-cyanoacrylate) and the optimum reinforcing combination for suturing wounds.

    PubMed

    Chigira, Miho; Akimoto, Masataka

    2005-01-01

    The adhesion strength of a skin adhesive, octyl-2-cyanoacrylate (Dermabond), was measured under various conditions using porcine skin. The combined use of a skin adhesive and a skin closure tape (n = 5) was significantly stronger than a single application of skin adhesive (n = 5) (p < 0.01). We have tentatively named the wound closure in which a skin adhesive and reinforcement material were combined the Reinforcing Combination Method. To obtain optimum conditions, further studies were done for sequence of application, type of reinforcement material, a number of layers, and width of the suture. The optimum condition for the reinforcement combination was established by applying one layer of skin adhesive over a skin closure tape, over one layer of skin adhesive, with a suture width of 4 cm. This reinforcement combination might be useful in clinical practice.

  13. Effects of chlorhexidine in self-etching adhesive: 24 hours results.

    PubMed

    Nishitani, Yoshihiro; Hosaka, Keiichi; Hoshika, Tomohiro; Yoshiyama, Masahiro; Pashley, David H

    2013-01-01

    It is known that chlorhexidine (CHX) does not inhibit micro-tensile bond strengths (MTBS) when it is used in etch-and-rinse adhesives. In that technique, CHX is applied to dentin as a primer after phosphoric acid-etching before bonding with Single Bond. It would be more convenient if it is possible to incorporate CHX into the adhesive. The purpose of this study was to compare the MTBS and the FT-IR percent conversion of an all-in-one self-etching adhesives contained varying concentration of CHX. Extracted human third molars were bonded with a control all-in-one adhesive or experimental versions containing 0.5, 1, 2 or 5% CHX. The MTBS and the percent conversion of experimental adhesives containing up to 1% CHX were not significantly CHX-free control adhesives. However, addition of 2 or especially 5% CHX experimental adhesives produced significant reductions in both the MTBS and the percent conversion.

  14. 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.

  15. 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.

  16. Willow: a uniform search interface.

    PubMed Central

    Ketchell, D S; Freedman, M M; Jordan, W E; Lightfoot, E M; Heyano, S; Libbey, P A

    1996-01-01

    The objective of the Willow Project is to develop a uniform search interface that allows a diverse community of users to retrieve information from heterogeneous network-based information resources. Willow separates the user interface from the database management or information retrieval system. It provides a graphic user interface to a variety of information resources residing on diverse hosts, and using different search engines and idiomatic query languages through networked-based client-server and Transmission Control Protocol/Internet Protocol (TCP/IP) protocols. It is based on a "database driver'' model, which allows new database hosts to be added without altering Willow itself. Willow employs a multimedia extension mechanism to launch external viewers to handle data in almost any form. Drivers are currently available for a local BRS/SEARCH system and the Z39.50 protocol. Students, faculty, clinicians, and researchers at the University of Washington are currently offered 30 local and remote databases via Willow. They conduct more than 250,000 sessions a month in libraries, medical centers and clinics, laboratories, and offices, and from home. The Massachusetts Institute of Technology is implementing Willow as its uniform search interface to Z39.50 hosts. PMID:8750388

  17. Mechanosensitive components of integrin adhesions: Role of vinculin

    PubMed Central

    Atherton, Paul; Stutchbury, Ben; Jethwa, Devina; Ballestrem, Christoph

    2016-01-01

    External forces play a key role in shaping development and normal physiology. Aberrant responses to forces, or changes in the nature of such forces, are implicated in a variety of diseases. Cells contain several types of adhesions, linking them to their external environment. It is through these adhesions that forces are both sensed (from the outside inwards) and applied (from inside to out). Furthermore, several adhesion-based proteins are sensitive to changes in intracellular forces, utilising them for activation and regulation. Here, we outline how vinculin, a key component of integrin-mediated adhesions linking the actin cytoskeleton to the extracellular matrix (ECM), is regulated by force and acts as force transducing protein. We discuss the role of vinculin in vivo and its place in health and disease; summarise the proposed mechanisms by which vinculin is recruited to and activated at integrin-ECM adhesions; and discuss recent findings that place vinculin as the major force sensing and transmitting component of cell–matrix adhesion complexes. Finally, we discuss the role of vinculin in regulating the cellular responses to both the physical properties of the external environment and to externally applied physical stimuli. PMID:26607713

  18. Simulation of Cell Adhesion using a Particle Transport Model

    NASA Astrophysics Data System (ADS)

    Chesnutt, Jennifer

    2005-11-01

    An efficient computational method for simulation of cell adhesion through protein binding forces is discussed. In this method, the cells are represented by deformable elastic particles, and the protein binding is represented by a rate equation. The method is first developed for collision and adhesion of two similar cells impacting on each other from opposite directions. The computational method is then applied in a particle-transport model for a cloud of interacting and colliding cells, each of which are represented by particles of finite size. One application might include red blood cells adhering together to form rouleaux, which are chains of red blood cells that are found in different parts of the circulatory system. Other potential applications include adhesion of platelets to a blood vessel wall or mechanical heart valve, which is a precursor of thrombosis formation, or adhesion of cancer cells to organ walls in the lymphatic, circulatory, digestive or pulmonary systems.

  19. Effect of thermal aging on the tensile bond strength at reduced areas of seven current adhesives.

    PubMed

    Baracco, Bruno; Fuentes, M Victoria; Garrido, Miguel A; González-López, Santiago; Ceballos, Laura

    2013-07-01

    The purpose of this study was to determine the micro-tensile bond strength (MTBS) to dentin of seven adhesive systems (total and self-etch adhesives) after 24 h and 5,000 thermocycles. Dentin surfaces of human third molars were exposed and bonded with two total-etch adhesives (Adper Scotchbond 1 XT and XP Bond), two two-step self-etch adhesives (Adper Scotchbond SE and Filtek Silorane Adhesive System) and three one-step self-etch adhesives (G-Bond, Xeno V and Bond Force). All adhesive systems were applied following manufacturers' instructions. Composite buildups were constructed and the bonded teeth were then stored in water (24 h, 37 °C) or thermocycled (5,000 cycles) before being sectioned and submitted to MTBS test. Two-way ANOVA and subsequent comparison tests were applied at α = 0.05. Characteristic de-bonded specimens were analyzed using scanning electron microscopy (SEM). After 24 h water storage, MTBS values were highest with XP Bond, Adper Scotchbond 1 XT, Filtek Silorane Adhesive System and Adper Scotchbond SE and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. After thermocycling, MTBS values were highest with XP Bond, followed by Filtek Silorane Adhesive System, Adper Scotchbond SE and Adper Scotchbond 1 XT and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. Thermal aging induced a significant decrease in MTBS values with all adhesives tested. The resistance of resin-dentin bonds to thermal-aging degradation was material dependent. One-step self-etch adhesives obtained the lowest MTBS results after both aging treatments, and their adhesive capacity was significantly reduced after thermocycling.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Characterization of adhesive from oysters: A structural and compositional study

    NASA Astrophysics Data System (ADS)

    Alberts, Erik

    The inability for man-made adhesives to set in wet or humid environments is an ongoing challenging the design of biomedical and marine adhesive materials. However, we see that nature has already overcome this challenge. Mussels, barnacles, oysters and sandcastle worms all have unique mechanisms by which they attach themselves to surfaces. By understanding what evolution has already spent millions of years perfecting, we can design novel adhesive materials inspired by nature's elegant designs. The well-studied mussel is currently the standard for design of marine inspired biomimetic polymers. In the work presented here, we aim to provide new insights into the adhesive produced by the eastern oyster, Crassostrea virginica. Unlike the mussel, which produces thread-like plaques comprised of DOPA containing-protein, the oyster secretes an organic-inorganic hybrid adhesive as it settles and grows onto a surface. This form of adhesion renders the oyster to be permanently fixed in place. Over time, hundreds of thousands of oyster grow and agglomerate to form extensive reef structures. These reefs are not only essential to survival of the oyster, but are also vital to intertidal ecosystems. While the shell of the oyster has been extensively studied, curiously, only a few conflicting insights have been made into the nature of the adhesive and contact zone between shell and substrate, and even lesfs information has been ascertained on organic and inorganic composition. In this work, we provide microscopy and histochemical studies to characterize the structure and composition of the adhesive, using oyster in the adult and juvenile stages of life. Preliminary work on extracting and characterizing organic components through collaborative help with solid-state NMR (SSNMR) and proteomics are also detailed here. We aim to provide a full, comprehensive characterization of oyster adhesive so that in the future, we may apply what we learn to the design of new materials.

  5. Investigation of Cell-Substrate Adhesion Properties of Living Chondrocyte by Measuring Adhesive Shear Force and Detachment Using AFM and Inverse FEA

    PubMed Central

    Nguyen, Trung Dung; Gu, YuanTong

    2016-01-01

    It is well-known that cell adhesion is important in many biological processes such as cell migration and proliferation. A better understanding of the cell adhesion process will shed insight into these cellular biological responses as well as cell adhesion-related diseases treatment. However, there is little research which has attempted to investigate the process of cell adhesion and its mechanism. Thus, this paper aims to study the time-dependent adhesion properties of single living chondrocytes using an advanced coupled experimental-numerical approach. Atomic Force Microscopy (AFM) tips will be used to apply lateral forces to detach chondrocytes that are seeded for three different periods. An advanced Finite Element Analysis (FEA) model combining porohyperelastic (PHE) constitutive model and cohesive zone formulation is developed to explore the mechanism of adhesion. The results revealed that the cells can resist normal traction better than tangential traction in the beginning of adhesion. This is when the cell adhesion molecules establish early attachment to the substrates. After that when the cells are spreading, stress fiber bundles generate tangential traction on the substrate to form strong adhesion. Both simulation and experimental results agree well with each other, providing a powerful tool to study the cellular adhesion process. PMID:27892536

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  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. Attitudes of Parents about School Uniforms.

    ERIC Educational Resources Information Center

    West, Charles K.; Tidwell, Diane K.; Bomba, Anne K.; Elmore, Patsy Alexander

    1999-01-01

    Responses from 144 parents of fourth graders showed that 56% favored uniforms in public schools; most agreed that uniforms contributed to a conducive learning environment, promoted school spirit, and discouraged violence; and most disagreed that uniforms cost more than other types of clothing. (SK)

  15. Design methodology for nano-engineered surfaces to control adhesion: Application to the anti-adhesion of particles

    NASA Astrophysics Data System (ADS)

    Kim, Taekyung; Min, Cheongwan; Jung, Myungki; Lee, Jinhyung; Park, Changsu; Kang, Shinill

    2016-12-01

    With increasing demand for means of controlling surface adhesion in various applications, including the semiconductor industry, optics, micro/nanoelectromechanical systems, and the medical industry, nano-engineered surfaces have attracted much attention. This study suggests a design methodology for nanostructures using the Derjaguin approximation in conjunction with finite element analysis for the control of adhesion forces. The suggested design methodology was applied for designing a nano-engineered surface with low-adhesion properties. To verify this, rectangular and sinusoidal nanostructures were fabricated and analyzed using force-distance curve measurements using atomic force microscopy and centrifugal detachment testing. For force-distance curve measurements, modified cantilevers with tips formed with atypical particles were used. Subsequently, centrifugal detachment tests were also conducted. The surface wettability of rectangular and sinusoidal nanostructures was measured and compared with the measured adhesion force and the number of particles remaining after centrifugal detachment tests.

  16. Uniform Projectile Motion: Dynamics, Symmetries and Conservation Laws

    NASA Astrophysics Data System (ADS)

    Swaczyna, Martin; Volný, Petr

    2014-04-01

    A geometric nonholonomic theory is applied to the problem of uniform projectile motion, i.e. motion of a projectile with constant instantaneous speed. The problem is investigated from the kinematic and dynamic point of view. Corresponding kinematic parameters of classical and uniform projectile motion are compared, nonholonomic Hamilton equations are derived and their solvability is discussed. Symmetries and conservation laws of the considered system are studied, the nonholonomic formulation of a conservation law of generalized energy is found as one of the corresponding Noetherian first integrals of this nonholonomic system.

  17. Uniformly dense polymeric foam body

    DOEpatents

    Whinnery, Jr., Leroy

    2003-07-15

    A method for providing a uniformly dense polymer foam body having a density between about 0.013 g/cm.sup.3 to about 0.5 g/cm.sup.3 is disclosed. The method utilizes a thermally expandable polymer microsphere material wherein some of the microspheres are unexpanded and some are only partially expanded. It is shown that by mixing the two types of materials in appropriate ratios to achieve the desired bulk final density, filling a mold with this mixture so as to displace all or essentially all of the internal volume of the mold, heating the mold for a predetermined interval at a temperature above about 130.degree. C., and then cooling the mold to a temperature below 80.degree. C. the molded part achieves a bulk density which varies by less then about .+-.6% everywhere throughout the part volume.

  18. STRUCTURE OF UNIFORMLY ROTATING STARS

    SciTech Connect

    Deupree, Robert G.

    2011-07-10

    Zero-age main-sequence models of uniformly rotating stars have been computed for 10 masses between 1.625 and 8 M{sub sun} and for 21 rotation rates from zero to nearly critical rotation. The surface shape is used to distinguish rotation rather than the surface equatorial velocity or the rotation rate. Using the surface shape is close, but not quite equivalent, to using the ratio of the rotation rate to the critical rotation rate. Using constant shape as the rotation variable means that it and the mass are separable, something that is not true for either the rotation rate or surface equatorial velocity. Thus, a number of properties, including the ratio of the effective temperature anywhere on the surface to the equatorial temperature, are nearly independent of the mass of the model, as long as the rotation rate changes in such a way as to keep the surface shape constant.

  19. A Review of Cell Adhesion Studies for Biomedical and Biological Applications

    PubMed Central

    Ahmad Khalili, Amelia; Ahmad, Mohd Ridzuan

    2015-01-01

    Cell adhesion is essential in cell communication and regulation, and is of fundamental importance in the development and maintenance of tissues. The mechanical interactions between a cell and its extracellular matrix (ECM) can influence and control cell behavior and function. The essential function of cell adhesion has created tremendous interests in developing methods for measuring and studying cell adhesion properties. The study of cell adhesion could be categorized into cell adhesion attachment and detachment events. The study of cell adhesion has been widely explored via both events for many important purposes in cellular biology, biomedical, and engineering fields. Cell adhesion attachment and detachment events could be further grouped into the cell population and single cell approach. Various techniques to measure cell adhesion have been applied to many fields of study in order to gain understanding of cell signaling pathways, biomaterial studies for implantable sensors, artificial bone and tooth replacement, the development of tissue-on-a-chip and organ-on-a-chip in tissue engineering, the effects of biochemical treatments and environmental stimuli to the cell adhesion, the potential of drug treatments, cancer metastasis study, and the determination of the adhesion properties of normal and cancerous cells. This review discussed the overview of the available methods to study cell adhesion through attachment and detachment events. PMID:26251901

  20. Preparation and testing of plant seed meal-based wood adhesives.

    PubMed

    He, Zhongqi; Chapital, Dorselyn C

    2015-03-05

    Recently, the interest in plant seed meal-based products as wood adhesives has steadily increased, as these plant raw materials are considered renewable and environment-friendly. These natural products may serve as alternatives to petroleum-based adhesives to ease environmental and sustainability concerns. This work demonstrates the preparation and testing of the plant seed-based wood adhesives using cottonseed and soy meal as raw materials. In addition to untreated meals, water washed meals and protein isolates are prepared and tested. Adhesive slurries are prepared by mixing a freeze-dried meal product with deionized water (3:25 w/w) for 2 hr. Each adhesive preparation is applied to one end of 2 wood veneer strips using a brush. The tacky adhesive coated areas of the wood veneer strips are lapped and glued by hot-pressing. Adhesive strength is reported as the shear strength of the bonded wood specimen at break. Water resistance of the adhesives is measured by the change in shear strength of the bonded wood specimens at break after water soaking. This protocol allows one to assess plant seed-based agricultural products as suitable candidates for substitution of synthetic-based wood adhesives. Adjustments to the adhesive formulation with or without additives and bonding conditions could optimize their adhesive properties for various practical applications.

  1. 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.

  2. 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.

  3. 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.

  4. Adhesive bonding and the use of corrosion resistant primers. [for metal surface preparation

    NASA Technical Reports Server (NTRS)

    Hockridge, R. R.; Thibault, H. G.

    1972-01-01

    The use of an anti-corrosive primer has been shown to be essential to assure survival of a bonded structure in a hostile environment, particularly if a stress is to be applied to the adhesively bonded joint during the environmental exposure. For example, the Lockheed L-1011 TriStar assembly, after exhaustive evaluation tests specifies use of chromate filled inhibitive polysulfide sealants, and use of corrosion inhibiting adhesive primers prior to structural bonding with film adhesive.

  5. Uniformly Rotating Single Substance Bodies

    NASA Astrophysics Data System (ADS)

    Leonard, Charles Michael Leo

    This dissertation explicitly and in detail solves the extended rotator problem in the uncharged relativistic classical cases of most physical interest. It shows that no plausible relativistic solutions exist in the literature of the extended rotator and that the point rotator solutions sometimes ballyhooed are not to be taken seriously. Explicit energy speedratio functions, angular momentum speedratio functions, Hamiltonian, Lagrangian, and other important characteristic functions of the state of uniform rotation of the extended body are detailed. This dissertation does not retreat to an 'analysis' of just the point rotator --which so many others have done and done incorrectly, or at best misleadingly, by hiding implausible assumptions in manifestly covariant formats. Assumptions in the model are not hidden but are brought out and analyzed as to their relevance for highlighting the core of the uniform rotation physics. Neither does the author hide any ignorance of the internal holding field for the rotator. Formulae for the characteristic Minimum Holding Field are explicitly given and their relativistic relevance is shown. The demonstration that such fields can be ignored in the energy and angular momentum expressions is completely detailed. The explicit Stress-Energy Tensor for the entire closed rotator system is given with all that entails as to the inescapability of the results from out of that mathematics. The generality of the finiteness of the extreme relativistic rotational limit is detailed and explained with its stark essential contrast to the infinite limit in the case of extreme relativistic translation of a body. The rotator is shown to possess a rich mathematical structure. Many elegant interconnection formulae are found as well as new Hamiltonian formulae --sometimes of considerable complexity. Exact rotator formulae as well as graphs, tables, and even interesting approximations are provided. New nonlinear differential equations are discovered and

  6. Fabrication of Planar Laser Targets with Sub-Micrometer Thickness Uniformity

    SciTech Connect

    Bono, M J; Castro, C; Hibbard, R L

    2005-07-21

    Lawrence Livermore National Laboratory routinely manufactures planar laser targets that consist of stacked and bonded foils for physics experiments on high-energy lasers. One recent planar laser target, the Equation of State target, had extremely tight specifications. The target required four bonded layers with thickness uniformities of several hundred nm, and the adhesive bonds between the layers could not exceed a few {micro}m. This paper describes the manufacturing process that was developed to meet these specifications.

  7. 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.

  8. 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

  9. UV-cured adhesives for carbon fiber composite applications

    NASA Astrophysics Data System (ADS)

    Lu, Hsiao-Chun

    Carbon fiber composite materials are increasingly used in automobile, marine, and aerospace industries due to their unique properties, including high strength, high stiffness and low weight. However, due to their brittle characteristic, these structures are prone to physical damage, such as a bird strike or impact damage. Once the structure is damaged, it is important to have fast and reliable temporary repair until the permanent repair or replacement can take place. In this dissertation, UV-based adhesives were used to provide a bonding strength for temporary repair. Adhesively bonded patch repair is an efficient and effective method for temporary repair. In this study, precured patches (hard patches) and dry fabric patches with laminating resins (soft patches) were performed. UV-based epoxy adhesives were applied to both patch repair systems. For precured patch repair, the bonding strengths were investigated under different surface treatments for bonding area and different adhesives thicknesses. The shear stresses of different UV exposure times and curing times were tested. Besides, the large patch repair was investigated as well. For soft patch repair, the hand wet lay-up was applied due to high viscosity of UV resins. A modified single lap shear testing (ASTM D5868) was applied to determine the shear stress. The large patches used fiber glass instead of carbon fiber to prove the possibility of repair with UV epoxy resin by hand wet lay-up process. The hand lay-up procedure was applied and assisted by vacuum pressure to eliminate the air bubbles and consolidate the patches. To enhance the bonding strength and effective soft patch repair, vacuum assisted resin transferring molding (VaRTM) is the better option. However, only low viscosity resins can be operated by VaRTM. Hence, new UV-based adhesives were formulated. The new UV-based adhesives included photoinitiator (PI), epoxy and different solvents. Solvents were used to compound the photoinitiator into epoxy

  10. The effect of different adhesive system applications on push-out bond strengths of glass fiber posts

    PubMed Central

    Deniz Arısu, Hacer; Üçtaşlı, Mine Betül; Okay, Tufan Can

    2013-01-01

    PURPOSE Over the past years, the adhesion of fiber posts luted with simplified adhesive systems has been a matter of great interest. The aim of this study was to assess the post retentive potential of a self-adhesive resin cement using different adhesive systems to compare the push-out bond strengths of fiber posts. MATERIALS AND METHODS The post spaces of 56 mandibular premolar roots were prepared and divided into 4 experimental groups and further divided into 2 subgroups according to testing time (n=7). The fiber posts (Rely X Fiber Post) were luted with a self-adhesive resin cement (RelyX Unicem) and one of the following adhesive systems: no adhesive, a total-etch adhesive resin (Single Bond), a two-step self-etch adhesive resin (Clearfil SE Bond) and a one-step self-etch adhesive resin (Clearfil S3 Bond). Each root was cut horizontally, and 1.5 mm thick six root segments were prepared. Push-out tests were performed after one week or three months (0.5 mm/min). Statistical analysis were performed with three-way ANOVA (α=.05). RESULTS Cervical root segments showed higher bond strength values than middle segments. Adhesive application increased the bond strength. For one week group, the total-etch adhesive resin Single Bond showed higher bond strength than the self-adhesive resin cement RelyX Unicem applied without adhesive resin at middle region. For 3 months group, the two-step self-etch adhesive resin Clearfil SE Bond showed the highest bond strength for both regions. Regarding the time considered, Clearfil SE Bond 3 months group showed higher bond strength values than one week group. CONCLUSION Using the adhesive resins in combination with the self-adhesive resin cement improves the bond strengths. The bond strength values of two-step self-etch adhesive resin Clearfil SE Bond improved as time passes. PMID:24049572

  11. 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

  12. 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

  13. 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.

  14. 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

  15. Instantly switchable adhesion of bridged fibrillar adhesive via gecko-inspired detachment mechanism and its application to a transportation system

    NASA Astrophysics Data System (ADS)

    Bae, Won-Gyu; Kim, Doogon; Suh, Kahp-Yang

    2013-11-01

    Inspired by the exceptional climbing ability of gecko lizards, artificial fibrillar adhesives have been extensively studied over the last decade both experimentally and theoretically. Therefore, a new leap towards practical uses beyond the academic horizon is timely and highly anticipated. To this end, we present a fibrillar adhesive in the form of bridged micropillars and its application to a transportation system with the detachment mechanism inspired by the climbing behaviour of gecko lizards. The adhesive shows strong normal attachment (~30 N cm-2) as well as easy and fast detachment within 0.5 s without involving complex dynamic mechanisms or specific stimulus-responsive materials. The fabrication of the bridged micropillars consists of replica moulding of polydimethylsiloxane (PDMS) micropillars, transfer of the PDMS precursor to the heads of the micropillars, and inverse placement on an inert Teflon-coated surface. Owing to the spontaneous interconnections of low viscosity PDMS precursor, bridged micropillars with a uniform capping nanomembrane (~800 nm thickness) are formed over a large area. Interestingly, macroscopic adhesion in the normal direction can be immediately switched between on and off states by changing the two detachment modes of pulling and peeling, respectively. To prove the potential of the fibrillar adhesive for practical use, an automated transportation system is demonstrated for lifting and releasing a mass of stacked glass slides over 1000 cycles of attachment and detachment.Inspired by the exceptional climbing ability of gecko lizards, artificial fibrillar adhesives have been extensively studied over the last decade both experimentally and theoretically. Therefore, a new leap towards practical uses beyond the academic horizon is timely and highly anticipated. To this end, we present a fibrillar adhesive in the form of bridged micropillars and its application to a transportation system with the detachment mechanism inspired by the

  16. 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

  17. Optimally Functionalized Adhesion for Contact Transfer Printing of Plasmonic Nanostructures on Flexible Substrate.

    PubMed

    Lee, Jihye; Lee, Jun-Young; Yeo, Jong-Souk

    2017-02-01

    This paper demonstrates a facile method to achieve high yield and uniform fabrication for the transfer printing of nanoplasmonic structures on a flexible substrate by providing novel understanding on adhesion layers. The mercapto alkyl carboxylic acids and the alkyl dithiols are used as functionalized adhesion layers and further optimized by controlling the terminal group as well as the length and composition of the functionalization on flat and nanostructured gold surfaces. Our approach of optimized adhesion has been successfully implemented to the transfer printing of functionalized gold nanostructure arrays, thus producing much higher yield of 97.6% and uniform fabrication of nanostructures on a flexible substrate and enabling applications such as flexible nanoplasmonic devices and biosensing platforms.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. Uniform sampling table method and its applications: establishment of a uniform sampling method.

    PubMed

    Chen, Yibin; Chen, Jiaxi; Wang, Wei

    2013-01-01

    A novel uniform sampling method is proposed in this paper. According to the requirements of uniform sampling, we propose the properties that must be met by analyzing the distribution of samples. Based on this, the proposed uniform sampling method is demonstrated and evaluated strictly by mathematical means such as inference. The uniform sampling tables with respect to Cn(t2) and Cn(t3) are established. Furthermore, a one-dimension uniform sampling method and a multidimension method are proposed. The proposed novel uniform sampling method, which is guided by uniform design theory, enjoys the advantages of simplified use and good representativeness of the whole sample.

  5. Improvement of uniformity in a weakly magnetized inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Lee, W. H.; Cheong, H. W.; Kim, J. W.; Whang, K. W.

    2015-12-01

    Magnetic fields are applied to inductively coupled plasma (ICP) to achieve high plasma densities using electromagnets. If the magnetic fields are set up such that the magnitude of magnetic flux density on the substrate decreases with both radial and axial distances from the substrate’s center (here after referred to as M-ICP-A), the plasma density increases by 237% compared with that for ICP although the non-uniformity of the plasma density for M-ICP-A (11.1%) is higher than that for ICP (10.9%). As the rate of decrease in the magnitude of magnetic flux density on the substrate increases both radially and axially, the non-uniformity in the plasma density increases further. The increase in the non-uniformity for M-ICP-A was confirmed to arise from the flute instability. To suppress the flute instability, we arranged the magnitude of magnetic flux density on the substrate to increase with increasing distance from the substrate center both radially and axially (here after referred to as M-ICP-V). In this configuration, plasma fluctuations were not observed, hence the plasma density non-uniformity was lowered to 8.1%, although the measured plasma density was higher than that for M-ICP-A. The oxide etch-rate non-uniformity in M-ICP-V (2.5%) was also lower than that for ICP (5.2%) or that for M-ICP-A (21.4%).

  6. [Studies on the use of tissue adhesives in cataract microsurgery].

    PubMed

    Hermel, B

    1980-01-01

    Corneal incision employed according to Paufique's method for microsurgical cataract removal was dressed with cyanoacrylic adhesive Histoacryl n-blau after the previous wound filling with biological adhesive from freeze dried human plasma. The experiments were performed on 80 enucleated cattle eyeballs and on 60 eyeballs of rabbits. The material were divided into groups depending on the method of wound dressing. In the I group wounds were dressed with adaptation sutures according to the Liegard method and filled with biological adhesive; cyanoacrylic adhesive was applied supplementary. In the II group wounds were filled with biological adhesive and sutured. In the III group wounds were only sutured. The rabbits were observed for 21 days and the resistance of wound anastomosis examined. In the I group wound resistance immediately after the operation and after 24 hours was found to be two times higher than in other groups. 7 days after the operation the values obtained in all groups were similar. In all groups the eyeballs irritation was similar within the first five days. 7 days after the operation plates of cyanoacrylic adhesive were removed without difficulties. In all groups linear corneal scars with mistiness 2 mm wide was found, also singular blood vessels penetrating the cornea were observed.

  7. Optimization and experimental validation of electrostatic adhesive geometry

    NASA Astrophysics Data System (ADS)

    Ruffatto, D.; Shah, J.; Spenko, M.

    This paper introduces a method to optimize the electrode geometry of electrostatic adhesives for robotic gripping, attachment, and manipulation applications. Electrostatic adhesion is achieved by applying a high voltage potential, on the order of kV, to a set of electrodes, which generates an electric field. The electric field polarizes the substrate material and creates an adhesion force. Previous attempts at creating electro-static adhesives have shown them to be effective, but researchers have made no effort to optimize the electrode configuration and geometry. We have shown that by optimizing the geometry of the electrode configuration, the electric field strength, and therefore the adhesion force, is enhanced. To accomplish this, Comsol Multiphysics was utilized to evaluate the average electric field generated by a given electrode geometry. Several electrode patterns were evaluated, including parallel conductors, concentric circles, Hilbert curves (a fractal geometry) and spirals. The arrangement of the electrodes in concentric circles with varying electrode widths proved to be the most effective. The most effective sizing was to use the smallest gap spacing allowable coupled with a variable electrode width. These results were experimentally validated on several different surfaces including drywall, wood, tile, glass, and steel. A new manufacturing process allowing for the fabrication of thin, conformal electro-static adhesive pads was utilized. By combining the optimized electrode geometry with the new fabrication process we are able to demonstrate a marked improvement of up to 500% in shear pressure when compared to previously published values.

  8. Effects of MMP Inhibitors Incorporated within Dental Adhesives

    PubMed Central

    Almahdy, A.; Koller, G.; Sauro, S.; Bartsch, J.W.; Sherriff, M.; Watson, T.F.; Banerjee, A.

    2012-01-01

    Matrix metalloproteinase (MMP) inhibition has been shown to reduce adhesive bond degradation when applied as a pre-conditioner, adding to clinical steps in the placement of adhesives, but their incorporation within dental adhesives has not been fully explored. This study examined the effect of including 2 MMP inhibitors (BB94 and GM6001) within the primers of 3 commercially available adhesives. Fluorometric assay and zymography showed that adhesives with MMP inhibitors had high affinity toward both synthetic fluorogenic FRET peptides (95%) and dentin powder substrates, respectively. The immediate microtensile bond strength was enhanced for 2 types of adhesives following the addition of both inhibitors. However, no changes were detected between the control and the inhibitor groups following 3-month storage. The modified two-step etch-and-rinse and single-step systems showed less Rhodamine B penetration to the “hybrid layer” and to the “adhesive”, respectively. The incorporation of BB94 and GM6001 within the primers resulted in the inhibition of dentin MMPs with improved initial bond strength and enhanced sealing ability. PMID:22518030

  9. Nano-anisotropic surface coating based on drug immobilized pendant polymer to suppress macrophage adhesion response.

    PubMed

    Kaladhar, K; Renz, H; Sharma, C P

    2015-04-01

    Exploring drug molecules for material design, to harness concepts of nano-anisotropy and ligand-receptor interactions, are rather elusive. The aim of this study is to demonstrate the bottom-up design of a single-step and bio-interactive polymeric surface coating, based on drug based pendant polymer. This can be applied on to polystyrene (PS) substrates, to suppress macrophage adhesion and spreading. The drug molecule is used in this coating for two purposes. The first one is drug as a "pendant" group, to produce nano-anisotropic properties that can enable adhesion of the coatings to the substrate. The second purpose is to use the drug as a "ligand", to produce ligand-receptor interaction, between the bound ligand and receptors of albumin, to develop a self-albumin coat over the surface, by the preferential binding of albumin in biological environment, to reduce macrophage adhesion. Our in silico studies show that, diclofenac (DIC) is an ideal drug based "ligand" for albumin. This can also act as a "pendant" group with planar aryl groups. The combination of these two factors can help to harness, both nano-anisotropic properties and biological functions to the polymeric coating. Further, the drug, diclofenac (DIC) is immobilized to the polyvinyl alcohol (PVA), to develop the pendant polymer (PVA-DIC). The interaction of bound DIC with the albumin is a ligand-receptor based interaction, as per the studies by circular dichroism, differential scanning calorimetry, and SDS-PAGE. The non-polar π-π* interactions are regulating; the interactions between PVA bound DIC-DIC interactions, leading to "nano-anisotropic condensation" to form distinct "nano-anisotropic segments" inside the polymeric coating. This is evident from, the thermo-responsiveness and uniform size of nanoparticles, as well as regular roughness in the surface coating, with similar properties as that of nanoparticles. In addition, the hydrophobic DIC-polystyrene (PS) interactions, between the PVA

  10. Uniform-burning matrix burner

    SciTech Connect

    Bohn, Mark S.; Anselmo, Mark

    2001-01-01

    Computer simulation was used in the development of an inward-burning, radial matrix gas burner and heat pipe heat exchanger. The burner and exchanger can be used to heat a Stirling engine on cloudy days when a solar dish, the normal source of heat, cannot be used. Geometrical requirements of the application forced the use of the inward burning approach, which presents difficulty in achieving a good flow distribution and air/fuel mixing. The present invention solved the problem by providing a plenum with just the right properties, which include good flow distribution and good air/fuel mixing with minimum residence time. CFD simulations were also used to help design the primary heat exchanger needed for this application which includes a plurality of pins emanating from the heat pipe. The system uses multiple inlet ports, an extended distance from the fuel inlet to the burner matrix, flow divider vanes, and a ring-shaped, porous grid to obtain a high-temperature uniform-heat radial burner. Ideal applications include dish/Stirling engines, steam reforming of hydrocarbons, glass working, and any process requiring high temperature heating of the outside surface of a cylindrical surface.

  11. Uniform guidelines improve client care.

    PubMed

    Barnett, B

    1994-12-01

    Uniform national guidelines on the delivery of family planning methods and services improve client care, assuming these guidelines are based on current scientific information. Compliance with these guidelines yields safe and efficient delivery of family planning services. Service providers need information, training, supplies, and guidelines to deliver quality services. Guidelines contribute to consistency among family planning programs in different settings. Even though clinics may not provide the same services, the guidelines allow them to provide the same standards of care. Specifically, eligibility criteria, contraindications, and follow-up schedules are the same regardless of the service delivery point. Various international health organizations (such as World Health Organization, USAID, Program for International Training in Health, International Planned Parenthood Federation, and Association for Voluntary Surgical Contraception) have developed guidelines for family planning service delivery. Governments can use these documents to develop national family planning guidelines and policies. They should adapt the guidelines to local needs and consider program resources. After development of the national guidelines, training, workshops, and dissemination of written materials should be provided for policymakers, physicians, nurses, and other health providers. Countries that have either developed or are working to draft their own national guidelines are Cameroon, Ghana, Mexico, and Nepal.

  12. Adhesive for polyester films cures at room temperature, has high initial tack

    NASA Technical Reports Server (NTRS)

    Christian, C. M.; Fust, G. W.; Welchel, C. J.

    1966-01-01

    Quick room-temperature-cure adhesive bonds polyester-insulated flat electrical cables to metal surfaces and various other substrates. The bond strength of the adhesive may be considerably increased by first applying a commercially available polyamide primer to the polyester film.

  13. 49 CFR 173.173 - Paint, paint-related material, adhesives, ink and resins.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Paint, paint-related material, adhesives, ink and... Than Class 1 and Class 7 § 173.173 Paint, paint-related material, adhesives, ink and resins. (a) When... requirements apply. Except as otherwise provided in this part, the description “Paint” is the proper...

  14. 49 CFR 173.173 - Paint, paint-related material, adhesives, ink and resins.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Paint, paint-related material, adhesives, ink and... Than Class 1 and Class 7 § 173.173 Paint, paint-related material, adhesives, ink and resins. (a) When... requirements apply. Except as otherwise provided in this part, the description “Paint” is the proper...

  15. 49 CFR 173.173 - Paint, paint-related material, adhesives, ink and resins.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Paint, paint-related material, adhesives, ink and... Than Class 1 and Class 7 § 173.173 Paint, paint-related material, adhesives, ink and resins. (a) When... requirements apply. Except as otherwise provided in this part, the description “Paint” is the proper...

  16. 49 CFR 173.173 - Paint, paint-related material, adhesives, ink and resins.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Paint, paint-related material, adhesives, ink and... Than Class 1 and Class 7 § 173.173 Paint, paint-related material, adhesives, ink and resins. (a) When... requirements apply. Except as otherwise provided in this part, the description “Paint” is the proper...

  17. 49 CFR 173.173 - Paint, paint-related material, adhesives, ink and resins.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Paint, paint-related material, adhesives, ink and... Than Class 1 and Class 7 § 173.173 Paint, paint-related material, adhesives, ink and resins. (a) When... requirements apply. Except as otherwise provided in this part, the description “Paint” is the proper...

  18. Single Cell Adhesion Assay Using Computer Controlled Micropipette

    PubMed Central

    Salánki, Rita; Hős, Csaba; Orgovan, Norbert; Péter, Beatrix; Sándor, Noémi; Bajtay, Zsuzsa; Erdei, Anna; Horvath, Robert; Szabó, Bálint

    2014-01-01

    Cell adhesion is a fundamental phenomenon vital for all multicellular organisms. Recognition of and adhesion to specific macromolecules is a crucial task of leukocytes to initiate the immune response. To gain statistically reliable information of cell adhesion, large numbers of cells should be measured. However, direct measurement of the adhesion force of single cells is still challenging and today’s techniques typically have an extremely low throughput (5–10 cells per day). Here, we introduce a computer controlled micropipette mounted onto a normal inverted microscope for probing single cell interactions with specific macromolecules. We calculated the estimated hydrodynamic lifting force acting on target cells by the numerical simulation of the flow at the micropipette tip. The adhesion force of surface attached cells could be accurately probed by repeating the pick-up process with increasing vacuum applied in the pipette positioned above the cell under investigation. Using the introduced methodology hundreds of cells adhered to specific macromolecules were measured one by one in a relatively short period of time (∼30 min). We blocked nonspecific cell adhesion by the protein non-adhesive PLL-g-PEG polymer. We found that human primary monocytes are less adherent to fibrinogen than their in vitro differentiated descendants: macrophages and dendritic cells, the latter producing the highest average adhesion force. Validation of the here introduced method was achieved by the hydrostatic step-pressure micropipette manipulation technique. Additionally the result was reinforced in standard microfluidic shear stress channels. Nevertheless, automated micropipette gave higher sensitivity and less side-effect than the shear stress channel. Using our technique, the probed single cells can be easily picked up and further investigated by other techniques; a definite advantage of the computer controlled micropipette. Our experiments revealed the existence of a sub

  19. Amygdalin influences bladder cancer cell adhesion and invasion in vitro.

    PubMed

    Makarević, Jasmina; Rutz, Jochen; Juengel, Eva; Kaulfuss, Silke; Tsaur, Igor; Nelson, Karen; Pfitzenmaier, Jesco; Haferkamp, Axel; Blaheta, Roman A

    2014-01-01

    The cyanogenic diglucoside amygdalin, derived from Rosaceae kernels, is employed by many patients as an alternative anti-cancer treatment. However, whether amygdalin indeed acts as an anti-tumor agent is not clear. Metastasis blocking properties of amygdalin on bladder cancer cell lines was, therefore, investigated. Amygdalin (10 mg/ml) was applied to UMUC-3, TCCSUP or RT112 bladder cancer cells for 24 h or for 2 weeks. Tumor cell adhesion to vascular endothelium or to immobilized collagen as well as tumor cell migration was examined. Effects of drug treatment on integrin α and β subtypes, on integrin-linked kinase (ILK) and total and activated focal adhesion kinase (FAK) were also determined. Integrin knock-down was carried out to evaluate integrin influence on migration and adhesion. A 24 h or 2 week amygdalin application distinctly reduced tumor cell adhesion and migration of UMUC-3 and RT112 cells. TCCSUP adhesion was also reduced, but migration was elevated under amygdalin. Integrin subtype expression was significantly and specifically altered by amygdalin depending on the cell line. ILK was moderately, and activated FAK strongly, lost in all tumor cell lines in the presence of amygdalin. Knock down of β1 integrin caused a significant decrease in both adhesion and migration of UMUC-3 cells, but a significant increase in TCCSUP adhesion. Knock down of β4 integrin caused a significant decrease in migration of RT112 cells. Since the different actions of amygdalin on the different cell lines was mirrored by β1 or β4 knock down, it is postulated that amygdalin influences adhesion and migratory properties of bladder cancer cells by modulating β1 or β4 integrin expression. The amygdalin induced increase in TCCSUP migratory behavior indicates that any anti-tumor benefits from amygdalin (seen with the other two cell lines) may depend upon the cancer cell type.

  20. Amygdalin Influences Bladder Cancer Cell Adhesion and Invasion In Vitro

    PubMed Central

    Makarević, Jasmina; Rutz, Jochen; Juengel, Eva; Kaulfuss, Silke; Tsaur, Igor; Nelson, Karen; Pfitzenmaier, Jesco

    2014-01-01

    The cyanogenic diglucoside amygdalin, derived from Rosaceae kernels, is employed by many patients as an alternative anti-cancer treatment. However, whether amygdalin indeed acts as an anti-tumor agent is not clear. Metastasis blocking properties of amygdalin on bladder cancer cell lines was, therefore, investigated. Amygdalin (10 mg/ml) was applied to UMUC-3, TCCSUP or RT112 bladder cancer cells for 24 h or for 2 weeks. Tumor cell adhesion to vascular endothelium or to immobilized collagen as well as tumor cell migration was examined. Effects of drug treatment on integrin α and β subtypes, on integrin-linked kinase (ILK) and total and activated focal adhesion kinase (FAK) were also determined. Integrin knock-down was carried out to evaluate integrin influence on migration and adhesion. A 24 h or 2 week amygdalin application distinctly reduced tumor cell adhesion and migration of UMUC-3 and RT112 cells. TCCSUP adhesion was also reduced, but migration was elevated under amygdalin. Integrin subtype expression was significantly and specifically altered by amygdalin depending on the cell line. ILK was moderately, and activated FAK strongly, lost in all tumor cell lines in the presence of amygdalin. Knock down of β1 integrin caused a significant decrease in both adhesion and migration of UMUC-3 cells, but a significant increase in TCCSUP adhesion. Knock down of β4 integrin caused a significant decrease in migration of RT112 cells. Since the different actions of amygdalin on the different cell lines was mirrored by β1 or β4 knock down, it is postulated that amygdalin influences adhesion and migratory properties of bladder cancer cells by modulating β1 or β4 integrin expression. The amygdalin induced increase in TCCSUP migratory behavior indicates that any anti-tumor benefits from amygdalin (seen with the other two cell lines) may depend upon the cancer cell type. PMID:25333694

  1. Single cell adhesion assay using computer controlled micropipette.

    PubMed

    Salánki, Rita; Hős, Csaba; Orgovan, Norbert; Péter, Beatrix; Sándor, Noémi; Bajtay, Zsuzsa; Erdei, Anna; Horvath, Robert; Szabó, Bálint

    2014-01-01

    Cell adhesion is a fundamental phenomenon vital for all multicellular organisms. Recognition of and adhesion to specific macromolecules is a crucial task of leukocytes to initiate the immune response. To gain statistically reliable information of cell adhesion, large numbers of cells should be measured. However, direct measurement of the adhesion force of single cells is still challenging and today's techniques typically have an extremely low throughput (5-10 cells per day). Here, we introduce a computer controlled micropipette mounted onto a normal inverted microscope for probing single cell interactions with specific macromolecules. We calculated the estimated hydrodynamic lifting force acting on target cells by the numerical simulation of the flow at the micropipette tip. The adhesion force of surface attached cells could be accurately probed by repeating the pick-up process with increasing vacuum applied in the pipette positioned above the cell under investigation. Using the introduced methodology hundreds of cells adhered to specific macromolecules were measured one by one in a relatively short period of time (∼30 min). We blocked nonspecific cell adhesion by the protein non-adhesive PLL-g-PEG polymer. We found that human primary monocytes are less adherent to fibrinogen than their in vitro differentiated descendants: macrophages and dendritic cells, the latter producing the highest average adhesion force. Validation of the here introduced method was achieved by the hydrostatic step-pressure micropipette manipulation technique. Additionally the result was reinforced in standard microfluidic shear stress channels. Nevertheless, automated micropipette gave higher sensitivity and less side-effect than the shear stress channel. Using our technique, the probed single cells can be easily picked up and further investigated by other techniques; a definite advantage of the computer controlled micropipette. Our experiments revealed the existence of a sub-population of

  2. Switching stiction and adhesion of a liquid on a solid

    NASA Astrophysics Data System (ADS)

    Mertens, Stijn F. L.; Hemmi, Adrian; Muff, Stefan; Gröning, Oliver; de Feyter, Steven; Osterwalder, Jürg; Greber, Thomas

    2016-06-01

    When a gecko moves on a ceiling it makes use of adhesion and stiction. Stiction—static friction—is experienced on microscopic and macroscopic scales and is related to adhesion and sliding friction. Although important for most locomotive processes, the concepts of adhesion, stiction and sliding friction are often only empirically correlated. A more detailed understanding of these concepts will, for example, help to improve the design of increasingly smaller devices such as micro- and nanoelectromechanical switches. Here we show how stiction and adhesion are related for a liquid drop on a hexagonal boron nitride monolayer on rhodium, by measuring dynamic contact angles in two distinct states of the solid-liquid interface: a corrugated state in the absence of hydrogen intercalation and an intercalation-induced flat state. Stiction and adhesion can be reversibly switched by applying different electrochemical potentials to the sample, causing atomic hydrogen to be intercalated or not. We ascribe the change in adhesion to a change in lateral electric field of in-plane two-nanometre dipole rings, because it cannot be explained by the change in surface roughness known from the Wenzel model. Although the change in adhesion can be calculated for the system we study, it is not yet possible to determine the stiction at such a solid-liquid interface using ab initio methods. The inorganic hybrid of hexagonal boron nitride and rhodium is very stable and represents a new class of switchable surfaces with the potential for application in the study of adhesion, friction and lubrication.

  3. Acoustic emission analysis: A test method for metal joints bonded by adhesives

    NASA Technical Reports Server (NTRS)

    Brockmann, W.; Fischer, T.

    1978-01-01

    Acoustic emission analysis is applied to study adhesive joints which had been subjected to mechanical and climatic stresses, taking into account conditions which make results applicable to adhesive joints used in aerospace technology. Specimens consisting of the alloy AlMgSi0.5 were used together with a phenolic resin adhesive, an epoxy resin modified with a polyamide, and an epoxy resin modified with a nitrile. Results show that the acoustic emission analysis provides valuable information concerning the behavior of adhesive joints under load and climatic stresses.

  4. 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.

  5. 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

  6. 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

  7. Particle adhesion studies relevant to chemical mechanical polishing.

    PubMed

    Lu, Zhenyu; Ryde, Niels P; Babu, S V; Matijević, Egon

    2005-10-25

    This study describes particle adhesion experiments carried out to elucidate interactions between particles in slurries used for polishing of wafers and disks. For this purpose the packed column technique was employed, which simulated chemical mechanical polishing of copper with silica and alumina, as well as of silicic oxide with ceria. The model systems consisted of uniform copper and glass beads as collectors, representing the wafers, and colloidal dispersions of silica, alumia, and silica coated with nanosize ceria, all of well-defined properties that are used as abrasives. It was shown that a strong correlation exists between deposition and detachment results of the adhesion studies and the polish rates measured using actual substrates with the same or similar slurries.

  8. Polymerization behavior within adhesive layer of one- and two-step self-etch adhesives: a micro-Raman spectroscopic study.

    PubMed

    Sakano, Wakae; Nakajima, Masatoshi; Prasansuttiporn, Taweesak; Foxton, Richard M; Tagami, Junji

    2013-01-01

    This study investigated the polymerization behavior within the adhesive layer of one- and two-step self-etch adhesives at the dentincomposite interface. Dentin surfaces were applied with Clearfil S(3) Bond (TS), Clearfil S(3) Bond Plus (TSP) and Clearfil SE Bond (SE), and then placed with a light-curing resin composite. After water storage for 24 h, the bonded teeth were sectioned and polished perpendicular to the adhesive interface, and the degree of conversion (DC) of the adhesive layer between the dentin and composite were determined using micro-Raman analysis. For all the adhesives, the DCs of the adhesive layers significantly decreased near the adhesive-composite join (p<0.05). For the maximum DC value (Pmax) and the DC value at the adhesive-composite join (Pitf), TS was significantly lower than TSP and SE (p<0.05). The polymerization of oxygen-inhibited layer at the top of the adhesive could not reach maximum DC even after polymerization of the overlying resin composite.

  9. 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

  10. 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

  11. 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

  12. The symbolism and myth surrounding nurses' uniform.

    PubMed

    Richardson, M

    This article addresses nurses' uniform from the perspective of the symbolic, myth, legend and competing discourse. The analysis touches upon why nurses working with people who have learning disabilities discarded the nurses' uniform and why other nurses may consider doing so, particularly if suitable alternatives exist. The analysis draws from various areas of nursing practice, including the nursing of disabled people, elderly people and people with learning disabilities. Nurses' uniform is revealed as a totem of considerable potency such that to wear a uniform in just any setting or context has to be cautioned. The practicalities of protective clothing are addressed. A differentiation is drawn between uniform and protective clothing such that much of the undesirable symbolism associated with uniform may be discarded with a consequent enhancement of the image of the nurse.

  13. 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.

  14. 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

  15. A new quantitative experimental approach to investigate single cell adhesion on multifunctional substrates.

    PubMed

    Canale, Claudio; Petrelli, Alessia; Salerno, Marco; Diaspro, Alberto; Dante, Silvia

    2013-10-15

    Cell adhesion is fundamental for the organization of cells in multicellular organisms since it has a key role in several physiological functions that drive tissue formation and development. A better knowledge of the affections that influence the adhesion capability of cells in several pathologies, such as cancer diseases or multiple sclerosis could enable the development of new therapeutical strategies. Whereas the optimal control of cell adhesion and growth on new technological materials is a primary issue in modern tissue engineering, few techniques are able to provide quantitative and reliable results on cell adhesion. We present a method that enables the investigation of cell adhesion at the single cell level and provides the capability to test the adhesion of a single cell on multifunctional substrates. To reach this goal we applied single cell force spectroscopy (SCFS) on custom designed patterns of molecules prepared on a rigid substrate by using a cantilever based molecule deposition tool, and we tested the adhesion of Chinese Hamster Ovary cells and Human Embrionic Kidney cells on two polyelectrolytes that are widely used as adhesive factors for cells growth: Polyethylenimine and Poly-D-Lysine. Our results confirm the common hypothesis on the mechanism of adhesion promotion by protonated molecules. Optimizations of the experimental settings of SFCS experiment are introduced here. The presented technique offers the unique opportunity to be extended to the study of cell adhesion on an unlimited number molecular species.

  16. Ultimate Control of Rate-Dependent Adhesion for Reversible Transfer Process via a Thin Elastomeric Layer.

    PubMed

    Kim, Chan; Yoon, Min-Ah; Jang, Bongkyun; Kim, Jae-Hyun; Lee, Hak-Joo; Kim, Kwang-Seop

    2017-03-30

    Adhesion between a stamp with an elastomeric layer and various devices or substrates is crucial to successfully fabricate flexible electronics using a transfer process. Although various transfer processes using stamps with different adhesion strengths have been suggested, the controllable range of adhesion is still limited to a narrow range. To precisely transfer devices onto selected substrates, however, the difference in adhesion between the picking and placing processes should be large enough to achieve a high yield. Herein, we report a simple way to extend the controllable adhesion range of stamps, which can be achieved by adjusting the thickness of the elastomeric layer and the separation velocity. The adhesion strength increased with decreasing layer thickness on the stamp due to a magnification of the confinement and rate-dependent effects on the adhesion. This enabled the controllable range of the adhesion strength for a 15 μm-thick elastomeric layer to be extended up to 12 times that of the bulk under the same separation conditions. The strategy of designing stamps using simple adhesion tests is also introduced, and the reversible transfer of thin Si chips was successfully demonstrated. Tuning and optimizing the adhesion strength of a stamp according to the design process suggested here can be applied to various materials for the selective transfer and replacement of individual devices.

  17. Electrochemically Tunable Cell Adsorption on a Transparent and Adhesion-Switchable Superhydrophobic Polythiophene Film.

    PubMed

    Xu, Lianyi; Chen, Shuangshuang; Lu, Xuemin; Lu, Qinghua

    2015-06-01

    A superhydrophobic polythiophene film (SSPTH) is prepared by double-layer electrodeposition on an indium tin oxide (ITO) glass electrode. This film shows not only electroresponsive superhydrophobic features, but also high transparency compared with the usual polythiophene film. The water-droplet adhesion on the SSPTH film can be switched between sliding and pinned states under the applied potential. More intresetingly, the change in water-droplet adhesion results in a change in cell adsorption on the SSPTH film. The low-adhesion (dedoped) SSPTH films can prevent Hela cell adhesion, whereas high-adhesion (doped) SSPTH films can promote Hela cell adsorption. This controllable cell adhesion on a SSPTH film may be developed as a smart biointerface material.

  18. Uniform Additivity in Classical and Quantum Information

    NASA Astrophysics Data System (ADS)

    Cross, Andrew; Li, Ke; Smith, Graeme

    2017-01-01

    Information theory quantifies the optimal rates of resource interconversions, usually in terms of entropies. However, nonadditivity often makes evaluating entropic formulas intractable. In a few auspicious cases, additivity allows a full characterization of optimal rates. We study uniform additivity of formulas, which is easily evaluated and captures all known additive quantum formulas. Our complete characterization of uniform additivity exposes an intriguing new additive quantity and identifies a remarkable coincidence—the classical and quantum uniformly additive functions with one auxiliary variable are identical.

  19. Hydraulic machine with non-uniform cascade

    NASA Astrophysics Data System (ADS)

    Haluza, M.; Pochylý, F.; Habán, V.

    2012-11-01

    In this article is introduced the sentence of an extension of operational zone of hydraulic machines. The problems of its extending is based on the design of non-uniform cascade. The non-uniform cascade is connected with other factors. The change of own frequency of the runner of a hydraulic machine and pressure pulsations. The suitable construction of non-uniform cascade is introduced on the results of computational simulation and experiment.

  20. Presence of adhesive vesicles in the mycoherbicide Alternaria helianthi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Alternaria helianthi conidia have been shown to cause disease on common cocklebur. Conidia were applied to slides made hydrophobic by coating with dimethyldicholorosilane (mimics leaf surface), then rinsed and treated with FITC-Con A to stain the adhesive material. Alternaria helianthi coni...

  1. 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

  2. [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.

  3. 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.

  4. Effect of spin current on uniform ferromagnetism: domain nucleation.

    PubMed

    Shibata, Junya; Tatara, Gen; Kohno, Hiroshi

    2005-02-25

    A large spin current applied to a uniform ferromagnet leads to a spin-wave instability as pointed out recently. In this Letter, it is shown that such spin-wave instability is absent in a state containing a domain wall, which indicates that nucleation of magnetic domains occurs above a certain critical spin current. This scenario is supported also by an explicit energy comparison of the two states under spin current.

  5. The Non-Equilibrium Thermodynamics and Kinetics of Focal Adhesion Dynamics

    PubMed Central

    Olberding, Joseph E.; Thouless, Michael D.; Arruda, Ellen M.; Garikipati, Krishna

    2010-01-01

    Background We consider a focal adhesion to be made up of molecular complexes, each consisting of a ligand, an integrin molecule, and associated plaque proteins. Free energy changes drive the binding and unbinding of these complexes and thereby controls the focal adhesion's dynamic modes of growth, treadmilling and resorption. Principal Findings We have identified a competition among four thermodynamic driving forces for focal adhesion dynamics: (i) the work done during the addition of a single molecular complex of a certain size, (ii) the chemical free energy change associated with the addition of a molecular complex, (iii) the elastic free energy change associated with deformation of focal adhesions and the cell membrane, and (iv) the work done on a molecular conformational change. We have developed a theoretical treatment of focal adhesion dynamics as a nonlinear rate process governed by a classical kinetic model. We also express the rates as being driven by out-of-equilibrium thermodynamic driving forces, and modulated by kinetics. The mechanisms governed by the above four effects allow focal adhesions to exhibit a rich variety of behavior without the need to introduce special constitutive assumptions for their response. For the reaction-limited case growth, treadmilling and resorption are all predicted by a very simple chemo-mechanical model. Treadmilling requires symmetry breaking between the ends of the focal adhesion, and is achieved by driving force (i) above. In contrast, depending on its numerical value (ii) causes symmetric growth, resorption or is neutral, (iii) causes symmetric resorption, and (iv) causes symmetric growth. These findings hold for a range of conditions: temporally-constant force or stress, and for spatially-uniform and non-uniform stress distribution over the FA. The symmetric growth mode dominates for temporally-constant stress, with a reduced treadmilling regime. Significance In addition to explaining focal adhesion dynamics, this

  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. Blister Test for Measurements of Adhesion and Adhesion Degradation of Organic Polymers on AA2024-T3

    NASA Astrophysics Data System (ADS)

    Rincon Troconis, Brendy Carolina

    A key parameter for the performance of corrosion protective coatings applied to metals is adhesion. Surface preparation prior to coating application is known to be critical, but there is a lack of understanding of what controls adhesion. Numerous techniques have been developed in the last decades to measure the adhesion strength of coatings to metals. Nonetheless, they are generally non-quantitative, non-reproducible, performed in dry conditions, or overestimate adhesion. In this study, a quantitative and reproducible technique, the Blister Test (BT), is used. The BT offers the ability to study the effects of a range of parameters, including the presence or absence of a wetting liquid, and simulates the stress situation in the coating/substrate interface. The effects of roughness and surface topography were studied by the BT and Optical Profilometry, using AA2024-T3 substrates coated with polyvinyl butyral (PVB). Random abrasion generated a surface with lower average roughness than aligned abrasion due to the continual cross abrasion of the grooves. The BT could discern the effects of different mechanical treatments. An adhesion strength indicator was defined and found to be a useful parameter. The effectiveness of standard adhesion techniques such as ASTM D4541 (Pull-off Test) and ASTM D3359 (Tape Test) was compared to the BT. Also, different attempts to measure adhesion and adhesion degradation of organic polymers to AA2024-T3 were tested. The pull-off test does not produce adhesive failure across the entire interface, while the tape test is a very qualitative technique and does not discern between the effects of different coating systems on the adhesion performance. The BT produces adhesive failure of the primer studied, is very reproducible, and is able to rank different coating systems. Therefore, it was found to be superior to the others. The approaches tested for adhesion degradation were not aggressive enough to have a measurable effect. The effects of

  8. Adhesion strength of sputtered TiAlN-coated WC insert tool

    SciTech Connect

    Budi, Esmar; Razali, M. Mohd.; Nizam, A. R. Md.

    2013-09-09

    The adhesion strength of TiAlN coating that deposited by using DC magnetron sputtering on WC insert tool are studied. TiAlN coating are deposited on Tungsten Carbide (WC) insert tool by varying negatively substrate bias from 79 to 221 volt and nitrogen flow rate from 30 to 72 sccm. The adhesion strength are obtained by using Rockwell indentation test method with a Brale diamond at applied load of 60,100 and 150 kgf. The lateral diameter of indentation is plotted on three different applied loads and the adhesion strength of TiAlN coating was obtained from the curved slopes at 100 and 150 kgf. The lower curve slop indicated better adhesion strength. The results shows that the adhesion strength of sputterred TiAlN coating tend to increase as the negatively substrate bias and nitrogen flow rate are increased.

  9. Adhesion strength of sputtered TiAlN-coated WC insert tool

    NASA Astrophysics Data System (ADS)

    Budi, Esmar; Razali, M. Mohd.; Nizam, A. R. Md.

    2013-09-01

    The adhesion strength of TiAlN coating that deposited by using DC magnetron sputtering on WC insert tool are studied. TiAlN coating are deposited on Tungsten Carbide (WC) insert tool by varying negatively substrate bias from 79 to 221 volt and nitrogen flow rate from 30 to 72 sccm. The adhesion strength are obtained by using Rockwell indentation test method with a Brale diamond at applied load of 60,100 and 150 kgf. The lateral diameter of indentation is plotted on three different applied loads and the adhesion strength of TiAlN coating was obtained from the curved slopes at 100 and 150 kgf. The lower curve slop indicated better adhesion strength. The results shows that the adhesion strength of sputterred TiAlN coating tend to increase as the negatively substrate bias and nitrogen flow rate are increased.

  10. 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

  11. 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

  12. Effectiveness and biocompatibility of a novel biological adhesive application for repair of meniscal tear on the avascular zone

    NASA Astrophysics Data System (ADS)

    Inoue, Takahito; Taguchi, Tetsushi; Imade, Shinji; Kumahashi, Nobuyuki; Uchio, Yuji

    2012-12-01

    We have investigated the effectiveness and safety of a newly developed biological adhesive for repair of meniscal tear. The adhesive was composed of disuccinimidyl tartrate (DST) as a crosslinker and human serum albumin (HSA) as a hardener. To determine adequate concentration, bonding strength was measured using a tensiometer 5 min after applying the adhesive on the avascular zone tear of porcine meniscus; it was compared with the strengths of commercially available cyanoacrylate-based and fibrin-based adhesives. In vivo examination was performed using Japanese white rabbits, creating longitudinal tears on the avascular zone of meniscus and applying DST-HSA adhesive. Three months after operation the rabbits were sacrificed and tension test and histological evaluation were performed. Bonding strength was measured in three porcine meniscus groups: (i) only suturing, (ii) suturing after applying the adhesive on surface and (iii) suturing using an adhesive-soaked suture. The optimum concentrations were 0.1 mmol of DST and 42 w/v% of HAS. Bonding strength was greatest with cyanoacrylate-based adhesive, followed by DST-HSA adhesive, and fibrin-based adhesive. No inflammation was observed in the synovium or surrounding tissues 3 months after using the DST-HSA adhesive. Bonding strength was greatest with DST-HSA adhesive-soaked suturing group (77 ± 6 N), followed by suturing only group (61 ± 5 N) and surface adhesive application group (60 ± 8 N). The newly developed DST-HSA adhesive is considered safe and may be effective in enforcement of bonding of avascular zone tear of the meniscus.

  13. School Dress Codes and Uniform Policies.

    ERIC Educational Resources Information Center

    Anderson, Wendell

    2002-01-01

    Opinions abound on what students should wear to class. Some see student dress as a safety issue; others see it as a student-rights issue. The issue of dress codes and uniform policies has been tackled in the classroom, the boardroom, and the courtroom. This Policy Report examines the whole fabric of the debate on dress codes and uniform policies…

  14. Student Dress Codes and Uniforms. Research Brief

    ERIC Educational Resources Information Center

    Johnston, Howard

    2009-01-01

    According to an Education Commission of the States "Policy Report", research on the effects of dress code and school uniform policies is inconclusive and mixed. Some researchers find positive effects; others claim no effects or only perceived effects. While no state has legislatively mandated the wearing of school uniforms, 28 states and…

  15. School Uniform Policies: Students' Views of Effectiveness.

    ERIC Educational Resources Information Center

    McCarthy, Teresa M.; Moreno, Josephine

    2001-01-01

    Focus-group interviews of New York City middle-school students about their perceptions of the effectiveness of the school-uniform policy. Finds that students' perceptions of the effects of school-uniform policy on school culture varied considerably with those intended by the principal. (Contains 40 references.) (PKP)

  16. School Uniforms and Discourses on Childhood.

    ERIC Educational Resources Information Center

    Bodine, Ann

    2003-01-01

    This ethnographic study examined the introduction of school uniforms in the public schools of one California city. Findings indicated that the uniform issue intersected with issues such as student safety and violence, family stress, egalitarianism, competitive dressing, and a power struggle over shaping the childhood environment. It was concluded…

  17. A School Uniform Program That Works.

    ERIC Educational Resources Information Center

    Loesch, Paul C.

    1995-01-01

    According to advocates, school uniforms reduce gang influence, decrease families' clothing expenditures, and help mitigate potentially divisive cultural and economic differences. Aiming to improve school climate, a California elementary school adopted uniforms as a source of pride and affiliation. This article describes the development of the…

  18. School Uniform Policies in Public Schools

    ERIC Educational Resources Information Center

    Brunsma, David L.

    2006-01-01

    The movement for school uniforms in public schools continues to grow despite the author's research indicating little if any impact on student behavior, achievement, and self-esteem. The author examines the distribution of uniform policies by region and demographics, the impact of these policies on perceptions of school climate and safety, and…

  19. Testing for uniformity in multidimensional data.

    PubMed

    Smith, S P; Jain, A K

    1984-01-01

    Testing for uniformity in multidimensional data is important in exploratory pattern analysis, statistical pattern recognition, and image processing. The goal of this paper is to determine whether the data follow the uniform distribution over some compact convex set in K-dimensional space, called the sampling window. We first provide a simple, computationally efficient method for generating a uniformly distributed sample over a set which approximates the convex hul of the data. We then test for uniformity by comparing this generated sample to the data by using Friedman-Rafsky's minimal spanning tree (MST) based test. Experiments with both simulated and real data indicate that this MST-based test is useful in deciding if data are uniform.

  20. 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.

  1. [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.

  2. 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.

  3. 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.

  4. Effect of a plant-based hemostatic agent on microleakage of self-etching adhesives

    PubMed Central

    Arslan, Soley; Ertaş, Hüseyin; Zorba, Yahya O.

    2013-01-01

    Objective: This in vitro study evaluated the effect of Ankaferd Blood Stopper (ABS) contamination on the microleakage of one-step and two-step self-etching adhesives. Study design: Class V cavities were prepared at the cemento-enamel junction on both buccal and lingual surfaces of 60 freshly extracted human molars. Teeth were randomly assigned into three groups according to contamination material applied (Group I, no contamination; Group II, blood contamination; Group III, ABS contamination). In contaminated groups, one drop of blood and ABS solution was applied directly to the dentin surface and air-dried. Each group was further divided into two subgroups according to bonding agent used [Group A, Clearfil SE Bond (two-step self-etching adhesive); Group B, Adper Easy One (one-step self-etching adhesive)]. Adhesive materials were applied according to the manufacturers’ recommendations. The specimens were restored using a universal microhybrid composite (Arabesk). After thermocycling (5000x, 5°C – 55°C) and immersion in a 0.5% basic fuchsin, dye penetration was evaluated under a stereomicroscope. Statistical analysis was performed with Kruskal-Wallis and Mann-Whitney U tests at p < 0.05. Results: Significantly higher microleakage scores were observed when one-step self-etching adhesive was applied to blood- and ABS-contaminated dentin. However, when a two-step self etching adhesive was used, microleakage was observed only following blood contamination, not following ABS contamination. Conclusions: Although, blood contamination before adhesive application resulted in increased microleakage with both one-step and two-step self-etching adhesive systems, ABS contamination did not affect microleakage when a two-step self-ething adhesive system was used. Key words:Ankaferd Blood Stopper, blood, microleakage, self-etching adhesive. PMID:23229238

  5. Hybrid inverse opals for regulating cell adhesion and orientation

    NASA Astrophysics Data System (ADS)

    Lu, Jie; Zheng, Fuyin; Cheng, Yao; Ding, Haibo; Zhao, Yuanjin; Gu, Zhongze

    2014-08-01

    Cell adhesion and alignment are two important considerations in tissue engineering applications as they can regulate the subsequent cell proliferation activity and differentiation program. Although many effects have been applied to regulate the adhesion or alignment of cells by using physical and chemical methods, it is still a challenge to regulate these cell behaviors simultaneously. Here, we present novel substrates with tunable nanoscale patterned structures for regulating the adhesion and alignment of cells. The substrates with different degrees of pattern orientation were achieved by customizing the amount of stretching applied to polymer inverse opal films. Cells cultured on these substrates showed an adjustable morphology and alignment. Moreover, soft hydrogels, which have poor plasticity and are difficult to cast into patterned structures, were applied to infiltrate the inverse opal structure. We demonstrated that the adhesion ratio of cells could be regulated by these hybrid substrates, as well as adjusting the cell morphology and alignment. These features of functional inverse opal substrates make them suitable for important applications in tissue engineering.

  6. Hybrid inverse opals for regulating cell adhesion and orientation.

    PubMed

    Lu, Jie; Zheng, Fuyin; Cheng, Yao; Ding, Haibo; Zhao, Yuanjin; Gu, Zhongze

    2014-09-21

    Cell adhesion and alignment are two important considerations in tissue engineering applications as they can regulate the subsequent cell proliferation activity and differentiation program. Although many effects have been applied to regulate the adhesion or alignment of cells by using physical and chemical methods, it is still a challenge to regulate these cell behaviors simultaneously. Here, we present novel substrates with tunable nanoscale patterned structures for regulating the adhesion and alignment of cells. The substrates with different degrees of pattern orientation were achieved by customizing the amount of stretching applied to polymer inverse opal films. Cells cultured on these substrates showed an adjustable morphology and alignment. Moreover, soft hydrogels, which have poor plasticity and are difficult to cast into patterned structures, were applied to infiltrate the inverse opal structure. We demonstrated that the adhesion ratio of cells could be regulated by these hybrid substrates, as well as adjusting the cell morphology and alignment. These features of functional inverse opal substrates make them suitable for important applications in tissue engineering.

  7. Model-based adhesive shrinkage compensation for increased bonding repeatability

    NASA Astrophysics Data System (ADS)

    Müller, Tobias; Schlette, Christian; Lakshmanan, Shunmuganathan; Haag, Sebastian; Zontar, Daniel; Sauer, Sebastian; Wenzel, Christian; Brecher, Christian; Roβmann, Jürgen

    2016-03-01

    The assembly process of optical components consists of two phases - the alignment and the bonding phase. Precision - or better process repeatability - is limited by the latter one. The limitation of the alignment precision is given by the measurement equipment and the manipulation technology applied. Today's micromanipulators in combination with beam imaging setups allow for an alignment in the range of far below 100nm. However, once precisely aligned optics need to be fixed in their position. State o f the art in optics bonding for laser systems is adhesive bonding with UV-curing adhesives. Adhesive bonding is a multi-factorial process and thus subject to statistical process deviations. As a matter of fact, UV-curing adhesives inherit shrinkage effects during their curing process, making offsets for shrinkage compensation mandatory. Enhancing the process control of the adhesive bonding process is the major goal of the activities described in this paper. To improve the precision of shrinkage compensation a dynamic shrinkage prediction is envisioned by Fraunhofer IPT. Intense research activities are being practiced to gather a deeper understanding of the parameters influencing adhesive shrinkage behavior. These effects are of different nature - obviously being the raw adhesive material itself as well as its condition, the bonding geometry, environmental parameters like surrounding temperature and of course process parameters such as curing properties. Understanding the major parameters and linking them in a model-based shrinkage-prediction environment is the basis for improved process control. Results are being deployed by Fraunhofer in prototyping, as well as volume production solutions for laser systems.

  8. An immersed boundary method for non-uniform Cartesian grids

    NASA Astrophysics Data System (ADS)

    Jang, Juwon; Lee, Changhoon

    2016-11-01

    Many kinds of immersed boundary method have been developed, but most of them have been used in uniform grids with discrete Dirac delta functions. Therefore, the distribution of Lagrangian points over the immersed surface is usually made uniformly. However, when any immersed boundary method is to be applied to non-uniform grids, uniform distribution might not be optimum for good performance. Recently, Akiki and Balachandar (2016) proposed a method to distribute the Lagrangian points nonuniformly over the surface of a sphere near the wall, but it cannot not be extended to more general shape of immersed surface. We propose a method that is capable for properly distributing the Lagrangian points over any kind of surface by considering the size of nearby Eulerian grids. Present method first finds intersection points between immersed surface and nonuniform Cartesian grids. Then, the centroid of the intersection points is projected on the immersed surface to be designated by Lagrangian point. This procedure guarantees one Lagrangian point per the Eulerian grid cell. This method is validated for various problems such as flows around a settling sphere, a moving sphere in the near-wall region and a tilted ellipsoid near the wall.

  9. Cyanoacrylate tissue adhesive for treatment of refractory corneal ulceration.

    PubMed

    Bromberg, Nancy M

    2002-03-01

    Isobutyl cyanoacrylate tissue adhesive (BCTA) was used in the treatment of refractory superficial corneal ulcers in 17 dogs, one cat, and one rabbit, present 2 weeks to 7 months (mean 6.8 weeks +/- 6.1) prior to referral. Little to no sedation was required in the majority of cases, with only topical anesthetic applied prior to debridement and BCTA application. The presence of the tissue adhesive caused mild discomfort for several days after application, as reported by the owners. The ulcers healed, and the tissue adhesive sloughed in approximately 3 weeks (+/- 1 week). Mild neovascularization of the cornea resolved with topical corticosteroids. The use of BCTA offers a simple, safe and noninvasive treatment for refractory corneal ulcers.

  10. Enhanced adhesion of bioinspired nanopatterned elastomers via colloidal surface assembly

    PubMed Central

    Akerboom, Sabine; Appel, Jeroen; Labonte, David; Federle, Walter; Sprakel, Joris; Kamperman, Marleen

    2015-01-01

    We describe a scalable method to fabricate nanopatterned bioinspired dry adhesives using colloidal lithography. Close-packed monolayers of polystyrene particles were formed at the air/water interface, on which polydimethylsiloxane (PDMS) was applied. The order of the colloidal monolayer and the immersion depth of the particles were tuned by altering the pH and ionic strength of the water. Initially, PDMS completely wetted the air/water interface outside the monolayer, thereby compressing the monolayer as in a Langmuir trough; further application of PDMS subsequently covered the colloidal monolayers. PDMS curing and particle extraction resulted in elastomers patterned with nanodimples. Adhesion and friction of these nanopatterned surfaces with varying dimple depth were studied using a spherical probe as a counter-surface. Compared with smooth surfaces, adhesion of nanopatterned surfaces was enhanced, which is attributed to an energy-dissipating mechanism during pull-off. All nanopatterned surfaces showed a significant decrease in friction compared with smooth surfaces. PMID:25392404

  11. Enhanced adhesion of bioinspired nanopatterned elastomers via colloidal surface assembly.

    PubMed

    Akerboom, Sabine; Appel, Jeroen; Labonte, David; Federle, Walter; Sprakel, Joris; Kamperman, Marleen

    2015-01-06

    We describe a scalable method to fabricate nanopatterned bioinspired dry adhesives using colloidal lithography. Close-packed monolayers of polystyrene particles were formed at the air/water interface, on which polydimethylsiloxane (PDMS) was applied. The order of the colloidal monolayer and the immersion depth of the particles were tuned by altering the pH and ionic strength of the water. Initially, PDMS completely wetted the air/water interface outside the monolayer, thereby compressing the monolayer as in a Langmuir trough; further application of PDMS subsequently covered the colloidal monolayers. PDMS curing and particle extraction resulted in elastomers patterned with nanodimples. Adhesion and friction of these nanopatterned surfaces with varying dimple depth were studied using a spherical probe as a counter-surface. Compared with smooth surfaces, adhesion of nanopatterned surfaces was enhanced, which is attributed to an energy-dissipating mechanism during pull-off. All nanopatterned surfaces showed a significant decrease in friction compared with smooth surfaces.

  12. Auger spectroscopy analysis in adhesion, friction and wear studies

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1977-01-01

    The paper reviews the current use of Auger electron spectroscopy in adhesion, friction, wear and lubrication studies. Conventional Auger spectroscopy is adopted to complement LEED studies of the adhesion of metal single crystals. In addition, Auger cylindrical mirror analysis is applied to the study of changes in surface chemistry during dynamic friction and wear experiments on polycrystalline metals and alloys. Important conclusions are that (1) segregation of alloying elements to the surface of metals can alter adhesion behavior; (2) hydrocarbons are adsorbed readily to clean iron surfaces at 23 C; (3) transfer from one surface to another for dissimilar materials in contact can be followed in sliding or rubbing friction studies; and (4) the friction process can enhance surface activity for metals with hydrocarbons.

  13. 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.

  14. 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.

  15. 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.

  16. Biostability of the Proanthocyanidins-Dentin Complex and Adhesion Studies.

    PubMed

    Leme-Kraus, A A; Aydin, B; Vidal, C M P; Phansalkar, R M; Nam, J W; McAlpine, J; Pauli, G F; Chen, S; Bedran-Russo, A K

    2017-04-01

    Oligomeric proanthocyanidins (OPACs) are potent and renewable natural bioactives possible to be refined into chemically standardized mixtures for biological applications. Herein, we found that multiscale interactions of OPACs with the dentin matrix create tight biointerfaces with hydrophobic methacrylate adhesives on wet surfaces. An enriched mixture of OPACs, with a known phytochemical profile, was produced from grape seed crude extract ( Vitis vinifera; enriched grape seed extract [e-GSE]) and applied to dentin matrices to determine changes to the mechanical properties and biodegradability of the dentin matrix and favorable resin adhesion mechanisms. Methods included a 3-point flexural test, quantification of hydroxyproline (collagen solubilization), static and dynamic nanomechanical analyses, resin-dentin microtensile bond strength, and micropermeability at the adhesive interface. The e-GSE-modified dentin matrix exhibited remarkably low collagen solubilization and sustained the bulk elastic properties over 12 mo. Tan δ findings reveal a more elastic-like behavior of the e-GSE-modified dentin matrix, which was not affected by H-bond destabilization by urea. Dentin-methacrylate biointerfaces with robust and stable adhesion were created on e-GSE-primed dentin surfaces, leading to a dramatic decrease of the interfacial permeability. Standardized OPAC mixtures provide a new mechanism of adhesion to type I collagen-rich tissues that does not rely on hydrophilic monomers. The bioadhesion mechanism involves physicochemical modifications to the dentin matrix, reduced tissue biodegradation, and bridging to methacrylate resins.

  17. Coordination of contractility, adhesion and flow in migrating Physarum amoebae

    PubMed Central

    Lewis, Owen L.; Zhang, Shun; Guy, Robert D.; del Álamo, Juan C.

    2015-01-01

    This work examines the relationship between spatio-temporal coordination of intracellular flow and traction stress and the speed of amoeboid locomotion of microplasmodia of Physarum polycephalum. We simultaneously perform particle image velocimetry and traction stress microscopy to measure the velocity of cytoplasmic flow and the stresses applied to the substrate by migrating Physarum microamoebae. In parallel, we develop a mathematical model of a motile cell which includes forces from the viscous cytosol, a poro-elastic, contractile cytoskeleton and adhesive interactions with the substrate. Our experiments show that flow and traction stress exhibit back-to-front-directed waves with a distinct phase difference. The model demonstrates that the direction and speed of locomotion are determined by this coordination between contraction, flow and adhesion. Using the model, we identify forms of coordination that generate model predictions consistent with experiments. We demonstrate that this coordination produces near optimal migration speed and is insensitive to heterogeneity in substrate adhesiveness. While it is generally thought that amoeboid motility is robust to changes in extracellular geometry and the nature of extracellular adhesion, our results demonstrate that coordination of adhesive forces is essential to producing robust migration. PMID:25904525

  18. Development and characteristics of an adhesion bioassay for ectocarpoid algae.

    PubMed

    Evariste, Emmanuelle; Gachon, Claire M M; Callow, Maureen E; Callow, James A

    2012-01-01

    Species of filamentous brown algae in the family Ectocarpaceae are significant members of fouling communities. However, there are few systematic studies on the influence of surface physico-chemical properties on their adhesion. In the present paper the development of a novel, laboratory-based adhesion bioassay for ectocarpoid algae, at an appropriate scale for the screening of sets of experimental samples in well-replicated and controlled experiments is described. The assays are based on the colonization of surfaces from a starting inoculum consisting of multicellular filaments obtained by blending the cultured alga Ectocarpus crouaniorum. The adhesion strength of the biomass after 14 days growth was assessed by applying a hydrodynamic shear stress. Results from adhesion tests on a set of standard surfaces showed that E. crouaniorum adhered more weakly to the amphiphilic Intersleek® 900 than to the more hydrophobic Intersleek® 700 and Silastic® T2 coatings. Adhesion to hydrophilic glass was also weak. Similar results were obtained for other cultivated species of Ectocarpus but differed from those obtained with the related ectocarpoid species Hincksia secunda. The response of the ectocarpoid algae to the surfaces was also compared to that for the green alga, Ulva.

  19. A test of the adhesion approximation for gravitational clustering

    NASA Technical Reports Server (NTRS)

    Melott, Adrian L.; Shandarin, Sergei F.; Weinberg, David H.

    1994-01-01

    We quantitatively compare a particle implementation of the adhesion approximation to fully nonlinear, numerical 'N-body' simulations. Our primary tool, cross-correlation of N-body simulations with the adhesion approximation, indicates good agreement, better than that found by the same test performed with the Zel'dovich approximation (hereafter ZA). However, the cross-correlation is not as good as that of the truncated Zel'dovich approximation (TZA), obtained by applying the Zel'dovich approximation after smoothing the initial density field with a Gaussian filter. We confirm that the adhesion approximation produces an excessively filamentary distribution. Relative to the N-body results, we also find that: (a) the power spectrum obtained from the adhesion approximation is more accurate that that from ZA to TZA, (b) the error in the phase angle of Fourier components is worse that that from TZA, and (c) the mass distribution function is more accurate than that from ZA or TZA. It appears that adhesion performs well statistically, but that TZA is more accurate dynamically, in the sense of moving mass to the right place.

  20. A test of the adhesion approximation for gravitational clustering

    NASA Technical Reports Server (NTRS)

    Melott, Adrian L.; Shandarin, Sergei; Weinberg, David H.

    1993-01-01

    We quantitatively compare a particle implementation of the adhesion approximation to fully non-linear, numerical 'N-body' simulations. Our primary tool, cross-correlation of N-body simulations with the adhesion approximation, indicates good agreement, better than that found by the same test performed with the Zel-dovich approximation (hereafter ZA). However, the cross-correlation is not as good as that of the truncated Zel-dovich approximation (TZA), obtained by applying the Zel'dovich approximation after smoothing the initial density field with a Gaussian filter. We confirm that the adhesion approximation produces an excessively filamentary distribution. Relative to the N-body results, we also find that: (a) the power spectrum obtained from the adhesion approximation is more accurate than that from ZA or TZA, (b) the error in the phase angle of Fourier components is worse than that from TZA, and (c) the mass distribution function is more accurate than that from ZA or TZA. It appears that adhesion performs well statistically, but that TZA is more accurate dynamically, in the sense of moving mass to the right place.

  1. Detecting cell-adhesive sites in extracellular matrix using force spectroscopy mapping

    PubMed Central

    Chirasatitsin, Somyot; Engler, Adam J

    2010-01-01

    The cell microenvironment is composed of extracellular matrix (ECM), which contains specific binding sites that allow the cell to adhere to its surroundings. Cells employ focal adhesion proteins, which must be able to resist a variety of forces to bind to ECM. Current techniques for detecting the spatial arrangement of these adhesions, however, have limited resolution and those that detect adhesive forces lack sufficient spatial characterization or resolution. Using a unique application of force spectroscopy, we demonstrate here the ability to determine local changes in the adhesive property of a fibronectin substrate down to the resolution of the fibronectin antibody-functionalized tip diameter, ~20 nm. To verify the detection capabilities of force spectroscopy mapping (FSM), changes in loading rate and temperature were used to alter the bond dynamics and change the adhesion force. Microcontact printing was also used to pattern fluorescein isothiocyanate-conjugated fibronectin in order to mimic the discontinuous adhesion domains of native ECM. Fluorescent detection was used to identify the pattern while FSM was used to map cell adhesion sites in registry with the initial fluorescent image. The results show that FSM can be used to detect the adhesion domains at high resolution and may subsequently be applied to native ECM with randomly distributed cell adhesion sites. PMID:21152375

  2. 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.

  3. Development and characterization of a novel hydrogel adhesive for soft tissue applications

    NASA Astrophysics Data System (ADS)

    Sanders, Lindsey Kennedy

    With laparoscopic and robotic surgical techniques advancing, the need for an injectable surgical adhesive is growing. To be effective, surgical adhesives for internal organs require bulk strength and compliance to avoid rips and tears, and adhesive strength to avoid leakage at the application site, while not hindering the natural healing process. Although a number of tissue adhesives and sealants approved by the FDA for surgical use are currently available, attaining a useful balance in all of these qualities has proven difficult, particularly when considering applications involving highly expandable tissue, such as bladder and lung. The long-term goal of this project is to develop a hydrogel-based tissue adhesive that provides proper mechanical properties to eliminate the need for sutures in various soft tissue applications. Tetronic (BASF), a 4-arm poly(propylene oxide)-poly(ethylene oxide) (PPO-PEO) block copolymer, has been selected as the base material for the adhesive hydrogel system. Solutions of Tetronic T1107 can support reverse thermal gelation at physiological temperatures, which can be combined with covalent crosslinking to achieve a "tandem gelation" process making it ideal for use as a tissue adhesive. The objective of this doctoral thesis research is to improve the performance of the hydrogel based tissue adhesive developed previously by Cho and co-workers by applying a multi-functionalization of Tetronic. Specifically, this research aimed to improve bonding strength of Tetronic tissue adhesive using bi-functional modification, incorporate hemostatic function to the bi-functional Tetronic hydrogel, and evaluate the safety of bi-functional Tetronic tissue adhesive both in vitro and in vivo. In summary, we have developed a fast-curing, mechanically strong hemostatic tissue adhesive that can control blood loss in wet conditions during wound treatment applications (bladder, liver and muscle). Specifically, the bi-functional Tetronic adhesive (TAS) with a

  4. Effect of adhesive layers on microshear bond strength of nanocomposite resin to dentin

    PubMed Central

    Ebrahim, Mohamed I.

    2017-01-01

    Background Bond strength of adhesive layer can absorb unwanted stresses of polymerization shrinkage in composite resin restorations; increased microshear bond strength can prevent failure of restoration materials, the purpose of this study was to evaluate the effect of adhesive layers on microshear bond strength of nanocomposite resin to dentin. Material and Methods Two different types of adhesive systems: universal adhesive (ExciTE) and newly developed adhesive (Nano-Bond), and one type of light-cured resin restorative material (Nanocomposite resin) were used in this study. The occlusal surfaces of extracted human molar teeth were ground perpendicular to the long axis of each tooth to expose a flat dentin surface. The adhesives were applied on dentin surfaces (single application or double application). Nanocomposite resin was then placed and light cured for 40 seconds. After 24 hours of immersion in water at 37°C, then subjected to thermocycling before testing, a microshear bond test was carried out. The data were analyzed by a two-way ANOVA. For comparison between groups, Tukey’s post-hoc test was used. Results The mean bond strengths of ExciTE and Nano-Bond adhesives with a single application were 8.8 and 16.6 MPa, respectively. The mean bond strengths of ExciTE and Nano-Bond adhesives with double application were 13.2 and 21.8MPa, respectively. There were no statistically significant differences in microshear bond strengths between the single application of Nano-Bond and the double application of ExciTE adhesives. Conclusions Microshear bond strength increased significantly as the applied adhesive layer was doubled. Key words:Adhesive, microshear, bond, strength, nanocomposite. PMID:28210433

  5. Doping suppression and mobility enhancement of graphene transistors fabricated using an adhesion promoting dry transfer process

    SciTech Connect

    Cheol Shin, Woo; Hun Mun, Jeong; Yong Kim, Taek; Choi, Sung-Yool; Jin Cho, Byung E-mail: tskim1@kaist.ac.kr; Yoon, Taeshik; Kim, Taek-Soo E-mail: tskim1@kaist.ac.kr

    2013-12-09

    We present the facile dry transfer of graphene synthesized via chemical vapor deposition on copper film to a functional device substrate. High quality uniform dry transfer of graphene to oxidized silicon substrate was achieved by exploiting the beneficial features of a poly(4-vinylphenol) adhesive layer involving a strong adhesion energy to graphene and negligible influence on the electronic and structural properties of graphene. The graphene field effect transistors (FETs) fabricated using the dry transfer process exhibit excellent electrical performance in terms of high FET mobility and low intrinsic doping level, which proves the feasibility of our approach in graphene-based nanoelectronics.

  6. Slow wave propagation in soft adhesive interfaces.

    PubMed

    Viswanathan, Koushik; Sundaram, Narayan K; Chandrasekar, Srinivasan

    2016-11-16

    Stick-slip in sliding of soft adhesive surfaces has long been associated with the propagation of Schallamach waves, a type of slow surface wave. Recently it was demonstrated using in situ experiments that two other kinds of slow waves-separation pulses and slip pulses-also mediate stick-slip (Viswanathan et al., Soft Matter, 2016, 12, 5265-5275). While separation pulses, like Schallamach waves, involve local interface detachment, slip pulses are moving stress fronts with no detachment. Here, we present a theoretical analysis of the propagation of these three waves in a linear elastodynamics framework. Different boundary conditions apply depending on whether or not local interface detachment occurs. It is shown that the interface dynamics accompanying slow waves is governed by a system of integral equations. Closed-form analytical expressions are obtained for the interfacial pressure, shear stress, displacements and velocities. Separation pulses and Schallamach waves emerge naturally as wave solutions of the integral equations, with oppositely oriented directions of propagation. Wave propagation is found to be stable in the stress regime where linearized elasticity is a physically valid approximation. Interestingly, the analysis reveals that slow traveling wave solutions are not possible in a Coulomb friction framework for slip pulses. The theory provides a unified picture of stick-slip dynamics and slow wave propagation in adhesive contacts, consistent with experimental observations.

  7. Interrogating adhesion using fiber Bragg grating sensing technology

    NASA Astrophysics Data System (ADS)

    Rasberry, Roger D.; Rohr, Garth D.; Miller, William K.; Udd, Eric; Blach, Noah T.; Davis, Ryan A.; Olson, Walter R.; Calkins, David; Roach, Allen R.; Walsh, David S.; McElhanon, James R.

    2015-05-01

    The assurance of the integrity of adhesive bonding at substrate interfaces is paramount to the longevity and sustainability of encapsulated components. Unfortunately, it is often difficult to non-destructively evaluate these materials to determine the adequacy of bonding after manufacturing and then later in service. A particularly difficult problem in this regard is the reliable detection/monitoring of regions of weak bonding that may result from poor adhesion or poor cohesive strength, or degradation in service. One promising and perhaps less explored avenue we have recently begun to investigate for this purpose centers on the use of (chirped) fiber Bragg grating sensing technology. In this scenario, a grating is patterned into a fiber optic such that a (broadband) spectral reflectance is observed. The sensor is highly sensitive to local and uniform changes across the length of the grating. Initial efforts to evaluate this approach for measuring adhesive bonding defects at substrate interfaces are discussed. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  8. Spectral degree of polarization uniformity for polarization-sensitive OCT.

    PubMed

    Baumann, Bernhard; Zotter, Stefan; Pircher, Michael; Götzinger, Erich; Rauscher, Sabine; Glösmann, Martin; Lammer, Jan; Schmidt-Erfurth, Ursula; Gröger, Marion; Hitzenberger, Christoph K

    Depolarization of light can be measured by polarization-sensitive optical coherence tomography (PS-OCT) and has been used to improve tissue discrimination as well as segmentation of pigmented structures. Most approaches to depolarization assessment for PS-OCT - such as the degree of polarization uniformity (DOPU) - rely on measuring the uniformity of polarization states using spatial evaluation kernels. In this article, we present a different approach which exploits the spectral dimension. We introduce the spectral DOPU for the pixelwise analysis of polarization state variations between sub-bands of the broadband light source spectrum. Alongside a comparison with conventional spatial and temporal DOPU algorithms, we demonstrate imaging in the healthy human retina, and apply the technique for contrasting hard exudates in diabetic retinopathy and investigating the pigment epithelium of the rat iris.

  9. Uniform algorithm for all-speed shock-capturing schemes

    NASA Astrophysics Data System (ADS)

    Li, Xue-song

    2014-07-01

    Many ideas exist for the development of shock-capturing schemes, such as Roe, Harten-Lax-van Leer (HLL) and advection upstream splitting method (AUSM) families, and their extension for all-speed flow. A uniform algorithm that expresses the three families in the same framework is proposed in this study. The algorithm has an explicit physical meaning, provides new understanding and comparison of the mechanism of schemes, and may play a significant role in further research. As an example of applying the uniform algorithm, the low Mach number behaviour of the schemes is analysed. A clear and simple explanation is provided based on the wall boundary, and a concise rule is proposed to determine whether a scheme has satisfied low Mach number behaviour.

  10. Spectral degree of polarization uniformity for polarization-sensitive OCT

    NASA Astrophysics Data System (ADS)

    Baumann, Bernhard; Zotter, Stefan; Pircher, Michael; Götzinger, Erich; Rauscher, Sabine; Glösmann, Martin; Lammer, Jan; Schmidt-Erfurth, Ursula; Gröger, Marion; Hitzenberger, Christoph K.

    2015-12-01

    Depolarization of light can be measured by polarization-sensitive optical coherence tomography (PS-OCT) and has been used to improve tissue discrimination as well as segmentation of pigmented structures. Most approaches to depolarization assessment for PS-OCT - such as the degree of polarization uniformity (DOPU) - rely on measuring the uniformity of polarization states using spatial evaluation kernels. In this article, we present a different approach which exploits the spectral dimension. We introduce the spectral DOPU for the pixelwise analysis of polarization state variations between sub-bands of the broadband light source spectrum. Alongside a comparison with conventional spatial and temporal DOPU algorithms, we demonstrate imaging in the healthy human retina, and apply the technique for contrasting hard exudates in diabetic retinopathy and investigating the pigment epithelium of the rat iris.

  11. Contiguous Uniform Deviation for Multiple Linear Regression in Pattern Recognition

    NASA Astrophysics Data System (ADS)

    Andriana, A. S.; Prihatmanto, D.; Hidaya, E. M. I.; Supriana, I.; Machbub, C.

    2017-01-01

    Understanding images by recognizing its objects is still a challenging task. Face elements detection has been developed by researchers but not yet shows enough information (low resolution in information) needed for recognizing objects. Available face recognition methods still have error in classification and need a huge amount of examples which may still be incomplete. Another approach which is still rare in understanding images uses pattern structures or syntactic grammars describing shape detail features. Image pixel values are also processed as signal patterns which are approximated by mathematical function curve fitting. This paper attempts to add contiguous uniform deviation method to curve fitting algorithm to increase applicability in image recognition system related to object movement. The combination of multiple linear regression and contiguous uniform deviation method are applied to the function of image pixel values, and show results in higher resolution (more information) of visual object detail description in object movement.

  12. 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.

  13. 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

  14. 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.

  15. Uniforms, status and professional boundaries in hospital.

    PubMed

    Timmons, Stephen; East, Linda

    2011-11-01

    Despite their comparative neglect analytically, uniforms play a key role in the delineation of occupational boundaries and the formation of professional identity in healthcare. This paper analyses a change to the system of uniforms in one UK hospital, where management have required all professions (with the exception of doctors) to wear the same 'corporate' uniform. Focus groups were conducted with the professionals and patients. We analyse this initiative as a kind of McDonaldisation, seeking to create a new 'corporate' worker whose allegiance is principally to the organisation, rather than a profession. Our findings show how important uniforms are to their wearers, both in terms of the defence of professional boundaries and status, as well as the construction of professional identity.

  16. 7 CFR 29.3563 - Uniformity.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign... tobacco as it is prepared for market. Uniformity is expressed in grade specifications as a percentage....

  17. Effects of beam irregularity on uniform scanning

    NASA Astrophysics Data System (ADS)

    Kim, Chang Hyeuk; Jang, Sea duk; Yang, Tae-Keun

    2016-09-01

    An active scanning beam delivery method has many advantages in particle beam applications. For the beam is to be successfully delivered to the target volume by using the active scanning technique, the dose uniformity must be considered and should be at least 2.5% in the case of therapy application. During beam irradiation, many beam parameters affect the 2-dimensional uniformity at the target layer. A basic assumption in the beam irradiation planning stage is that the shape of the beam is symmetric and follows a Gaussian distribution. In this study, a pure Gaussian-shaped beam distribution was distorted by adding parasitic Gaussian distribution. An appropriate uniform scanning condition was deduced by using a quantitative analysis based on the gamma value of the distorted beam and 2-dimensional uniformities.

  18. Uniform National Discharge Standards (UNDS): Outreach

    EPA Pesticide Factsheets

    Describes the Federalism and Tribal consultation efforts related to the Uniform National Discharge Standards (UNDS) and links to copies of each presentation, both to state and local representatives, as well as federally-recognized tribes.

  19. 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

  20. 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.

  1. 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.

  2. A method to screen and evaluate tissue adhesives for joint repair applications

    PubMed Central

    2012-01-01

    Background Tissue adhesives are useful means for various medical procedures. Since varying requirements cause that a single adhesive cannot meet all needs, bond strength testing remains one of the key applications used to screen for new products and study the influence of experimental variables. This study was conducted to develop an easy to use method to screen and evaluate tissue adhesives for tissue engineering applications. Method Tissue grips were designed to facilitate the reproducible production of substrate tissue and adhesive strength measurements in universal testing machines. Porcine femoral condyles were used to generate osteochondral test tissue cylinders (substrates) of different shapes. Viability of substrates was tested using PI/FDA staining. Self-bonding properties were determined to examine reusability of substrates (n = 3). Serial measurements (n = 5) in different operation modes (OM) were performed to analyze the bonding strength of tissue adhesives in bone (OM-1) and cartilage tissue either in isolation (OM-2) or under specific requirements in joint repair such as filling cartilage defects with clinical applied fibrin/PLGA-cell-transplants (OM-3) or tissues (OM-4). The efficiency of the method was determined on the basis of adhesive properties of fibrin glue for different assembly times (30 s, 60 s). Seven randomly generated collagen formulations were analyzed to examine the potential of method to identify new tissue adhesives. Results Viability analysis of test tissue cylinders revealed vital cells (>80%) in cartilage components even 48 h post preparation. Reuse (n = 10) of test substrate did not significantly change adhesive characteristics. Adhesive strength of fibrin varied in different test settings (OM-1: 7.1 kPa, OM-2: 2.6 kPa, OM-3: 32.7 kPa, OM-4: 30.1 kPa) and was increasing with assembly time on average (2.4-fold). The screening of the different collagen formulations revealed a substance with significant higher adhesive

  3. A new adhesive technique for internal fixation in midfacial surgery

    PubMed Central

    Endres, Kira; Marx, Rudolf; Tinschert, Joachim; Wirtz, Dieter Christian; Stoll, Christian; Riediger, Dieter; Smeets, Ralf

    2008-01-01

    Background The current surgical therapy of midfacial fractures involves internal fixation in which bone fragments are fixed in their anatomical positions with osteosynthesis plates and corresponding screws until bone healing is complete. This often causes new fractures to fragile bones while drilling pilot holes or trying to insert screws. The adhesive fixation of osteosynthesis plates using PMMA bone cement could offer a viable alternative for fixing the plates without screws. In order to achieve the adhesive bonding of bone cement to cortical bone in the viscerocranium, an amphiphilic bone bonding agent was created, analogous to the dentin bonding agents currently on the market. Methods The adhesive bonding strengths were measured using tension tests. For this, metal plates with 2.0 mm diameter screw holes were cemented with PMMA bone cement to cortical bovine bone samples from the femur diaphysis. The bone was conditioned with an amphiphilic bone bonding agent prior to cementing. The samples were stored for 1 to 42 days at 37 degrees C, either moist or completely submerged in an isotonic NaCl-solution, and then subjected to the tension tests. Results Without the bone bonding agent, the bonding strength was close to zero (0.2 MPa). Primary stability with bone bonding agent is considered to be at ca. 8 MPa. Moist storage over 42 days resulted in decreased adhesion forces of ca. 6 MPa. Wet storage resulted in relatively constant bonding strengths of ca. 8 MPa. Conclusion A new amphiphilic bone bonding agent was developed, which builds an optimizied interlayer between the hydrophilic bone surface and the hydrophobic PMMA bone cement and thus leads to adhesive bonding between them. Our in vitro investigations demonstrated the adhesive bonding of PMMA bone cement to cortical bone, which was also stable against hydrolysis. The newly developed adhesive fixing technique could be applied clinically when the fixation of osteosynthesis plates with screws is impossible. With

  4. Adhesive interactions of biologically inspired soft condensed matter

    NASA Astrophysics Data System (ADS)

    Anderson, Travers Heath

    Improving our fundamental understanding of the surface interactions between complex materials is needed to improve existing materials and products as well as develop new ones. The object of this research was to apply the measurements of fundamental surface interactions to real world problems facing chemical engineers and materials scientists. I focus on three systems of biologically inspired soft condensed matter, with an emphasis on the adhesive interactions between them. The formation of phospholipid bilayers of the neutral lipid, dimyristoyl-phosphatidylcholine (DMPC) on silica surfaces from vesicles in aqueous solutions was investigated. The process involves five stages: vesicle adhesion to the substrate surfaces, steric interactions with neighboring vesicles, rupture, spreading via hydrophobic fusion of bilayer edges, and ejection of excess lipid, trapped water and ions into the solution. The forces between DMPC bilayers and silica were measured in the Surface Forces Apparatus (SFA) in phosphate buffered saline. The adhesion energy was found to be much stronger than the expected adhesion predicted by van der Waals interactions, likely due to an attractive electrostatic interaction. The effects of non-adsorbing cationic polyelectrolytes on the interactions between supported cationic surfactant bilayers were studied using the SFA. Addition of polyelectrolyte has a number of effects on the interactions including the induction of a depletion-attraction and screening of the double-layer repulsion. Calculations are made that allow for the conversion of the adhesion energy measured in the SFA to the overall interaction energy between vesicles in solution, which determines the stability behavior of vesicle dispersions. Mussels use a variety of dihydroxyphenyl-alanine (DOPA) rich proteins specifically tailored to adhering to wet surfaces. The SFA was used to study the role of DOPA on the adhesive properties of these proteins to TiO 2 and mica using both real mussel

  5. Study of adhesion of vertically aligned carbon nanotubes to a substrate by atomic-force microscopy

    NASA Astrophysics Data System (ADS)

    Ageev, O. A.; Blinov, Yu. F.; Il'ina, M. V.; Il'in, O. I.; Smirnov, V. A.; Tsukanova, O. G.

    2016-02-01

    The adhesion to a substrate of vertically aligned carbon nanotubes (VA CNT) produced by plasmaenhanced chemical vapor deposition has been experimentally studied by atomic-force microscopy in the current spectroscopy mode. The longitudinal deformation of VA CNT by applying an external electric field has been simulated. Based on the results, a technique of determining VA CNT adhesion to a substrate has been developed that is used to measure the adhesion strength of connecting VA CNT to a substrate. The adhesion to a substrate of VA CNT 70-120 nm in diameter varies from 0.55 to 1.19 mJ/m2, and the adhesion force from 92.5 to 226.1 nN. When applying a mechanical load, the adhesion strength of the connecting VA CNT to a substrate is 714.1 ± 138.4 MPa, and the corresponding detachment force increases from 1.93 to 10.33 μN with an increase in the VA CNT diameter. As an external electric field is applied, the adhesion strength is almost doubled and is 1.43 ± 0.29 GPa, and the corresponding detachment force is changed from 3.83 to 20.02 μN. The results can be used in the design of technological processes of formation of emission structures, VA CNT-based elements for vacuum microelectronics and micro- and nanosystem engineering, and also the methods of probe nanodiagnostics of VA CNT.

  6. Monitoring in real-time focal adhesion protein dynamics in response to a discrete mechanical stimulus.

    PubMed

    von Bilderling, Catalina; Caldarola, Martín; Masip, Martín E; Bragas, Andrea V; Pietrasanta, Lía I

    2017-01-01

    The adhesion of cells to the extracellular matrix is a hierarchical, force-dependent, multistage process that evolves at several temporal scales. An understanding of this complex process requires a precise measurement of forces and its correlation with protein responses in living cells. We present a method to quantitatively assess live cell responses to a local and specific mechanical stimulus. Our approach combines atomic force microscopy with fluorescence imaging. Using this approach, we evaluated the recruitment of adhesion proteins such as vinculin, focal adhesion kinase, paxillin, and zyxin triggered by applying forces in the nN regime to live cells. We observed in real time the development of nascent adhesion sites, evident from the accumulation of early adhesion proteins at the position where the force was applied. We show that the method can be used to quantify the recruitment characteristic times for adhesion proteins in the formation of focal complexes. We also found a spatial remodeling of the mature focal adhesion protein zyxin as a function of the applied force. Our approach allows the study of a variety of complex biological processes involved in cellular mechanotransduction.

  7. 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.

  8. 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.

  9. 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.

  10. 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...

  11. 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.

  12. 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

  13. 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).

  14. Endothelial dysfunction and monocyte recruitment in cells exposed to non-uniform shear stress.

    PubMed

    Cicha, Iwona; Goppelt-Struebe, Margarete; Yilmaz, Atilla; Daniel, Werner G; Garlichs, Christoph D

    2008-01-01

    Atherosclerosis results from a combination of local blood flow patterns and systemic risk factors. We investigated whether non-uniform shear stress at bifurcations induces pro-atherogenic endothelial dysfunction and monocyte recruitment. Bifurcating flow-through cell culture slides were used to expose HUVECs to laminar or non-uniform shear stress for 18 h at 10 dyne/cm(2). For the adhesion assay, HUVECs were subsequently perfused with medium containing THP-1 monocytes for 1 h. Protein expression was determined by immunofluorescence. In areas exposed to laminar shear stress, alignment of endothelial cells with the flow was observed, accompanied by upregulation of eNOS and downregulation of connective tissue growth factor (CTGF). In contrast, cells exposed to non-uniform shear stress near the outer walls of bifurcations were characterized by irregular, unaligned shape, induction of endothelin-1 and CTGF, as well as reduced eNOS expression. These atherogenic effects of non-uniform shear stress were prevented when cells were treated with statins (1 mumol/l) during flow. Under non-uniform shear stress, a slight induction of VCAM-1, ICAM-1, and E-/P-selectin was observed. In agreement with this, monocyte recruitment, which was nearly undetectable under laminar shear stress, was moderately induced by non-uniform shear stress (P<0.02). In conclusion, inhibition of antioxidative eNOS and upregulation of atherogenic proteins is the first step in non-uniform shear stress-mediated endothelial dysfunction, which in vivo in the presence of atherogenic risk factors may further enhance monocyte recruitment into the artery wall.

  15. Glycocalyx Degradation Induces a Proinflammatory Phenotype and Increased Leukocyte Adhesion in Cultured Endothelial Cells under Flow

    PubMed Central

    McDonald, Karli K.; Cooper, Scott; Danielzak, Lisa; Leask, Richard L.

    2016-01-01

    Leukocyte adhesion to the endothelium is an early step in the pathogenesis of atherosclerosis. Effective adhesion requires the binding of leukocytes to their cognate receptors on the surface of endothelial cells. The glycocalyx covers the surface of endothelial cells and is important in the mechanotransduction of shear stress. This study aimed to identify the molecular mechanisms underlying the role of the glycocalyx in leukocyte adhesion under flow. We performed experiments using 3-D cell culture models, exposing human abdominal aortic endothelial cells to steady laminar shear stress (10 dynes/cm2 for 24 hours). We found that with the enzymatic degradation of the glycocalyx, endothelial cells developed a proinflammatory phenotype when exposed to uniform steady shear stress leading to an increase in leukocyte adhesion. Our results show an up-regulation of ICAM-1 with degradation compared to non-degraded controls (3-fold increase, p<0.05) and we attribute this effect to a de-regulation in NF-κB activity in response to flow. These results suggest that the glycocalyx is not solely a physical barrier to adhesion but rather plays an important role in governing the phenotype of endothelial cells, a key determinant in leukocyte adhesion. We provide evidence for how the destabilization of this structure may be an early and defining feature in the initiation of atherosclerosis. PMID:27907146

  16. Applied Stratigraphy

    NASA Astrophysics Data System (ADS)

    Lucas, Spencer G.

    Stratigraphy is a cornerstone of the Earth sciences. The study of layered rocks, especially their age determination and correlation, which are integral parts of stratigraphy, are key to fields as diverse as geoarchaeology and tectonics. In the Anglophile history of geology, in the early 1800s, the untutored English surveyor William Smith was the first practical stratigrapher, constructing a geological map of England based on his own applied stratigraphy. Smith has, thus, been seen as the first “industrial stratigrapher,” and practical applications of stratigraphy have since been essential to most of the extractive industries from mining to petroleum. Indeed, gasoline is in your automobile because of a tremendous use of applied stratigraphy in oil exploration, especially during the latter half of the twentieth century. Applied stratigraphy, thus, is a subject of broad interest to Earth scientists.

  17. Structural and compositional characterization of the adhesive produced by reef building oysters.

    PubMed

    Alberts, Erik M; Taylor, Stephen D; Edwards, Stephanie L; Sherman, Debra M; Huang, Chia-Ping; Kenny, Paul; Wilker, Jonathan J

    2015-04-29

    Oysters have an impressive ability to overcome difficulties of life within the stressful intertidal zone. These shellfish produce an adhesive for attaching to each other and building protective reef communities. With their reefs often exceeding kilometers in length, oysters play a major role in balancing the health of coastal marine ecosystems. Few details are available to describe oyster adhesive composition or structure. Here several characterization methods were applied to describe the nature of this material. Microscopy studies indicated that the glue is comprised of organic fiber-like and sheet-like structures surrounded by an inorganic matrix. Phospholipids, cross-linking chemistry, and conjugated organics were found to differentiate this adhesive from the shell. Symbiosis in material synthesis could also be present, with oysters incorporating bacterial polysaccharides into their adhesive. Oyster glue shows that an organic-inorganic composite material can provide adhesion, a property especially important when constructing a marine ecosystem.

  18. Evaluation of the mechanical properties of dental adhesives and glass-ionomer cements.

    PubMed

    Magni, Elisa; Ferrari, Marco; Hickel, Reinhard; Ilie, Nicoleta

    2010-02-01

    Adhesives and lining/base materials should relieve the stresses concentrated at the tooth/restoration interface. The study aimed at comparing the mechanical properties of eight adhesives and six glass-ionomer cements (GICs). The adhesives were applied on dentin disks, whereas 2 mm x 3 mm x 2 mm GICs specimens were prepared in a teflon mold. Vicker's hardness (VH), elastic modulus (E), creep (Cr) and elastic work (We/Wtot) were measured with a micro hardness indenter. One-way ANOVA and Tukey's test were used to compare the mechanical properties within each materials' type and among the materials' classes. Enamel and dentin were used as references. Significant differences were detected within each materials' type and among the materials' classes and enamel and dentin. GICs were superior to adhesives in VH and E and showed a VH similar to dentin. GICs presented mechanical properties more similar to enamel and dentin than adhesives.

  19. Preliminary evaluation of adhesion strength measurement devices for ceramic/titanium matrix composite bonds

    NASA Technical Reports Server (NTRS)

    Pohlchuck, Bobby; Zeller, Mary V.

    1992-01-01

    The adhesive bond between ceramic cement and a titanium matrix composite substrate to be used in the National Aerospace Plane program is evaluated. Two commercially available adhesion testers, the Sebastian Adherence Tester and the CSEM REVETEST Scratch Tester, are evaluated to determine their suitability for quantitatively measuring adhesion strength. Various thicknesses of cements are applied to several substrates, and bond strengths are determined with both testers. The Sabastian Adherence Tester has provided limited data due to an interference from the sample mounting procedure, and has been shown to be incapable of distinguishing adhesion strength from tensile and shear properties of the cement itself. The data from the scratch tester has been found to be difficult to interpret due to the porosity and hardness of the cement. Recommendations are proposed for a more reliable adhesion test method.

  20. Tetraspanin CD151 regulates alpha6beta1 integrin adhesion strengthening

    NASA Technical Reports Server (NTRS)

    Lammerding, Jan; Kazarov, Alexander R.; Huang, Hayden; Lee, Richard T.; Hemler, Martin E.

    2003-01-01

    The tetraspanin CD151 molecule associates specifically with laminin-binding integrins, including alpha6beta1. To probe strength of alpha6beta1-dependent adhesion to laminin-1, defined forces (0-1.5 nN) were applied to magnetic laminin-coated microbeads bound to NIH 3T3 cells. For NIH 3T3 cells bearing wild-type CD151, adhesion strengthening was observed, as bead detachment became more difficult over time. In contrast, mutant CD151 (with the C-terminal region replaced) showed impaired adhesion strengthening. Static cell adhesion to laminin-1, and detachment of beads coated with fibronectin or anti-alpha6 antibody were all unaffected by CD151 mutation. Hence, CD151 plays a key role in selectively strengthening alpha6beta1 integrin-mediated adhesion to laminin-1.

  1. FLRT Structure: Balancing Repulsion and Cell Adhesion in Cortical and Vascular Development

    PubMed Central

    Seiradake, Elena; del Toro, Daniel; Nagel, Daniel; Cop, Florian; Härtl, Ricarda; Ruff, Tobias; Seyit-Bremer, Gönül; Harlos, Karl; Border, Ellen Clare; Acker-Palmer, Amparo; Jones, E. Yvonne; Klein, Rüdiger

    2014-01-01

    Summary FLRTs are broadly expressed proteins with the unique property of acting as homophilic cell adhesion molecules and as heterophilic repulsive ligands of Unc5/Netrin receptors. How these functions direct cell behavior and the molecular mechanisms involved remain largely unclear. Here we use X-ray crystallography to reveal the distinct structural bases for FLRT-mediated cell adhesion and repulsion in neurons. We apply this knowledge to elucidate FLRT functions during cortical development. We show that FLRTs regulate both the radial migration of pyramidal neurons, as well as their tangential spread. Mechanistically, radial migration is controlled by repulsive FLRT2-Unc5D interactions, while spatial organization in the tangential axis involves adhesive FLRT-FLRT interactions. Further, we show that the fundamental mechanisms of FLRT adhesion and repulsion are conserved between neurons and vascular endothelial cells. Our results reveal FLRTs as powerful guidance factors with structurally encoded repulsive and adhesive surfaces. PMID:25374360

  2. Evaluation of a 4-META adhesive cement.

    PubMed

    Cooley, R L; Burger, K M; Chain, M C

    1991-01-01

    This study investigated the shear bond strength of a new 4-META adhesive cement (C & B-Metabond) to dentin and Ni-Cr-Be alloy (Rexillium III). Fifteen human molar teeth had dentin bonding sites prepared by grinding away the enamel on a water-cooled abrasive wheel to a 600 grit. Fifteen metal alloy specimens were cast, ground to a 600 grit, and air abraded with 50 micron alumina. The 4-META cement was applied to the dentin and metal in accordance with the manufacturer's instructions. After 24 hours in water at 37 degrees C, the shear bond strengths were recorded. The mean bond strength to dentin and the metal alloy was 20.1 megapascals.

  3. Marginal adaptation of composite resins under two adhesive techniques.

    PubMed

    Dačić, Stefan; Veselinović, Aleksandar M; Mitić, Aleksandar; Nikolić, Marija; Cenić, Milica; Dačić-Simonović, Dragica

    2016-11-01

    In the present research, different adhesive techniques were used to set up fillings with composite resins. After the application of etch and rinse or self etch adhesive technique, marginal adaptation of composite fillings was estimated by the length of margins without gaps, and by the microretention of resin in enamel and dentin. The study material consisted of 40 extracted teeth. Twenty Class V cavities were treated with 35% phosphorous acid and restored after rinsing by Adper Single Bond 2 and Filtek Ultimate-ASB/FU 3M ESPE composite system. The remaining 20 cavities were restored by Adper Easy One-AEO/FU 3M ESPE composite system. Marginal adaptation of composite fillings was examined using a scanning electron microscope (SEM). The etch and rinse adhesive technique showed a significantly higher percentage of margin length without gaps (in enamel: 92.5%, in dentin: 57.3%), compared with the self-etch technique with lower percentage of margin length without gaps, in enamel 70.4% (p < .001), and in dentin-22.6% (p < .05). In the first technique, microretention was composed of adhesive and hybrid layers as well as resin tugs in interprismatic spaces of enamel, while the dentin microretention was composed of adhesive and hybrid layers with resin tugs in dentin canals. In the second technique, resin tugs were rarely seen and a microgap was dominant along the border of restoration margins. The SEM analysis showed a better marginal adaptation of composite resin to enamel and dentin with better microretention when the etch and rinse adhesive procedure was applied.

  4. Uniform color space based on color matching

    NASA Astrophysics Data System (ADS)

    Liao, Shih-Fang; Yang, Tsung-Hsun; Lee, Cheng-Chung

    2007-09-01

    This research intends to explore with a uniform color space based on the CIE 1931 x-y chromatic coordinate system. The goal is to improve the non-uniformity of the CIE 1931 x-y chromaticity diagram such as to approach the human color sensation as possible; however, its simple methodology still can be kept. In spite of the existence of various kinds of the uniform color coordinate systems built up early (CIE u'-v', CIE Lab, CIE LUV, etc.), the establishment of a genuine uniform color space is actually still an important work both for the basic research in color science and the practical applications of colorimetry, especially for recent growing request in illumination engineering and in display technology. In this study, the MacAdam ellipses and the Munsell color chips are utilized for the comparison with the human color sensation. One specific linear transformation matrix is found for the CIE 1931 color matching functions (see manuscript) to become the novel uniform ones. With the aid of the optimization method, the transformation matrix can be easily discovered and makes the 25 MacAdam ellipses are similar to each other in the novel uniform color space. On the other hand, the perfectiveness of the equal-hue curves and the equal-chroma contours from the Mnusell color chips evaluates for the best optimization conditions among several different definitions for the similarity of all the MacAdam ellipses. Finally, the color difference between any two colors can be simply measured by the Euclidean distance in the novel uniform color space and is still fitted to the human color sensation.

  5. Applied oceanography

    SciTech Connect

    Bishop, J.M.

    1984-01-01

    This book combines oceanography principles and applications such as marine pollution, resources, and transportation. It is divided into two main parts treating the basic principles of physical oceanography, and presenting a unique systems framework showing how physical oceanography, marine ecology, economics, and government policy may be combined to define the newly developing field of applied oceanography.

  6. Applied Enzymology.

    ERIC Educational Resources Information Center

    Manoharan, Asha; Dreisbach, Joseph H.

    1988-01-01

    Describes some examples of chemical and industrial applications of enzymes. Includes a background, a discussion of structure and reactivity, enzymes as therapeutic agents, enzyme replacement, enzymes used in diagnosis, industrial applications of enzymes, and immobilizing enzymes. Concludes that applied enzymology is an important factor in…

  7. 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.

  8. Comparison of shear bond strength of two self-etch primer/adhesive systems.

    PubMed

    Bishara, Samir E; Ajlouni, Raed; Laffoon, John F; Warren, John J

    2006-01-01

    Orthodontic brackets adhesive systems use three different agents, an enamel conditioner, a primer solution, and an adhesive resin. A unique characteristic of some new bonding systems is that they combine the conditioning, priming, and adhesive agents into a single application. The purpose of this study was to assess and compare the effects of using one-step and two-step self-etch primer/adhesive systems on the shear bond strength of orthodontic brackets. The brackets were bonded to extracted human molars according to one of two protocols. Group I (control): a two-step self-etch acidic primer/adhesive system was used, Transbond Plus was applied to the enamel surface as suggested by the manufacturer. The brackets were bonded with Transbond XT and light cured for 20 seconds. Group II: a one-step self-etch, self-adhesive resin cement system, Maxcem, was applied directly to the bracket. The self-etch primer/adhesive is made of two components that mix automatically during application. The brackets were then light cured for 20 seconds. The mean shear bond strength of the two-step acid-etch primer/adhesive was 5.9 +/- 2.7 Mpa and the mean for the one-step system was 3.1 +/- 1.7 MPa. The in vitro findings of this study indicated that the shear bond strengths (t = 3.79) of the two adhesive systems were significantly different (P = .001). One-step adhesive systems could potentially be advantageous for orthodontic purposes if their bond strength can be improved.

  9. Uniformity of the lasing wavelength of heterogeneously integrated InP microdisk lasers on SOI.

    PubMed

    Mechet, P; Raineri, F; Bazin, A; Halioua, Y; Spuesens, T; Karle, T J; Regreny, P; Monnier, P; Van Thourhout, D; Sagnes, I; Raj, R; Roelkens, G; Morthier, G

    2013-05-06

    We report a high lasing wavelength uniformity of optically pumped InP-based microdisk lasers processed with electron-beam lithography, heterogeneously integrated with adhesive bonding on silicon-on-insulator (SOI) waveguide circuits and evanescently coupled to an underlying waveguide. We study the continuous wave laser emission coupling out of the SOI via a grating coupler etched at one side of the waveguide, and demonstrate a standard deviation in lasing wavelength of nominally identical devices on the same chip lower than 500 pm. The deviation in the diameter of the microdisks as low as a few nanometers makes all-optical signal processing applications requiring cascadability possible.

  10. 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.

  11. Double layer adhesive silicone dressing as a potential dermal drug delivery film in scar treatment.

    PubMed

    Mojsiewicz-Pieńkowska, Krystyna; Jamrógiewicz, Marzena; Żebrowska, Maria; Mikolaszek, Barbara; Sznitowska, Małgorzata

    2015-03-15

    The present studies focused on the evaluation of design of an adhesive silicone film intended for scar treatment. Developed silicone double layer film was examined in terms of its future relevance to therapy and applicability on the human skin considering properties which included in vitro permeability of water vapor and oxygen. In order to adapt the patches for medical use in the future there were tested such properties as in vitro adhesion and occlusion related to in vivo hydration. From the silicone rubbers double layer silicone film was prepared: a non-adhesive elastomer as a drug carrier (the matrix for active substances - enoxaparin sodium - low molecular weight heparin) and an adhesive elastomer, applied on the surface of the matrix. The novel adhesive silicone film was found to possess optimal properties in comparison to commercially available silicone dressing: adhesion in vivo, adhesion in vitro - 11.79N, occlusion F=85% and water vapor permeability in vitro - WVP=105g/m(2)/24h, hydration of stratum corneum in vivoH=61-89 (RSD=1.6-0.9%), oxygen permeation in vitro - 119-391 cm(3)/m(2)/24 (RSD=0.17%). In vitro release studies indicated sufficient LMWH release rate from silicone matrix. Developed novel adhesive silicone films were considered an effective treatment of scars and keloids and a potential drug carrier able to improve the effectiveness of therapy.

  12. Study of cell-matrix adhesion dynamics using surface plasmon resonance imaging ellipsometry.

    PubMed

    Kim, Se-Hwa; Chegal, Won; Doh, Junsang; Cho, Hyun Mo; Moon, Dae Won

    2011-04-06

    The interaction of cells with extracellular matrix, termed cell-matrix adhesions, importantly governs multiple cellular phenomena. Knowledge of the functional dynamics of cell-matrix adhesion could provide critical clues for understanding biological phenomena. We developed surface plasmon resonance imaging ellipsometry (SPRIE) to provide high contrast images of the cell-matrix interface in unlabeled living cells. To improve the contrast and sensitivity, the null-type imaging ellipsometry technique was integrated with an attenuated total reflection coupler. We verified that the imaged area of SPRIE was indeed a cell-matrix adhesion area by confocal microscopy imaging. Using SPRIE, we demonstrated that three different cell types exhibit distinct features of adhesion. SPRIE was applied to diverse biological systems, including during cell division, cell migration, and cell-cell communication. We imaged the cell-matrix anchorage of mitotic cells, providing the first label-free imaging of this interaction to our knowledge. We found that cell-cell communication can alter cell-matrix adhesion, possibly providing direct experimental evidence for cell-cell communication-mediated changes in cell adhesion. We also investigated shear-stress-induced adhesion dynamics in real time. Based on these data, we expect that SPRIE will be a useful methodology for studying the role of cell-matrix adhesion in important biological phenomena.

  13. Attenuation of leukocyte adhesion by recombinant TNF-binding protein after hemorrhagic shock in the rat.

    PubMed

    Maier, Marcus; Ströbele, Hubert; Voges, Jaqueline; Bauer, Clemens; Marzi, Ingo

    2003-05-01

    Ischemia/reperfusion injury involves a large number of humoral and cellular mediators that activate leukocytes that subsequently migrate to local tissues. Tumor necrosis factor (TNF)-alpha may be one of the most important mediators of this post-shock inflammatory response. In this study, we investigated the influence of a recombinant Type I (55 kDa) TNF-binding protein (TNF-BP) on leukocyte-endothelial interactions in the liver after hemorrhagic shock. Hemorrhagic shock was induced in female Sprague-Dawley rats (40 mmHg for 90 min) and a standardized resuscitation regimen was applied. At the time of resuscitation, animals were treated intravenously with either TNF-BP 4 mg/kg or placebo. The liver microcirculation was investigated using intravital fluorescence microscopy and immunohistochemistry at 5 h and 48 h after reperfusion. At 5 h, treatment with TNF-BP significantly reduced temporary leukocyte adhesion in the liver sinusoids as well as mean adhesion time of leukocytes in the hepatic central vein. In contrast, after 48 h, permanent leukocyte adhesion in the central hepatic vein was significantly reduced in the group receiving TNF-BP, whereas temporary leukocyte adhesion and mean adhesion time did not differ between the two groups. Both types of leukocyte adhesion, rolling adhesion after 5 h and firm adhesion after 48 h, were reduced in the group treated with TNF-BP, thereby suggesting a long-lasting anti-inflammatory effect.

  14. Evaluating uniformity of IR reference sources

    NASA Astrophysics Data System (ADS)

    Barrat, Catherine; Violleau, Sébastien

    2015-10-01

    Infrared reference sources such as blackbodies are used to calibrate and test IR sensors and cameras.. Applications requiring a high thermal uniformity over the emissive surface become more and more frequent compared to the past applications. Among these applications are non uniformity correction of infrared cameras focused at short distance and simultaneous calibration of a set of sensor facing a large area blackbody. Facing these demanding applications requires to accurately measuring thee thermal radiation of each point of the emissive surface of the reference source. The use of an infrared camera for this purpose turns out to be absolutely inefficient since the uniformity off response of this camera is usually worse than the uniformity of thee source to bee measured. Consequently, HGH has developed a testing bench for accurate measurement of uniformity of infrared sources based on a low noise radiometer mounted of translating stages and using an exclusive drift correction method. This bench delivers a reliable thermal map of any kind of infrared reference source.

  15. 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.

  16. 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.

  17. 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.

  18. Coatings of polyethylene glycol for suppressing adhesion between solid microspheres and flat surfaces.

    PubMed

    Upadhyayula, Srigokul; Quinata, Timothy; Bishop, Stephen; Gupta, Sharad; Johnson, Noah Ray; Bahmani, Baharak; Bozhilov, Kliment; Stubbs, Jeremy; Jreij, Pamela; Nallagatla, Pratima; Vullev, Valentine I

    2012-03-20

    This article describes the development and the examination of surface coatings that suppress the adhesion between glass surfaces and polymer microspheres. Superparamagnetic doping allowed for exerting magnetic forces on the microbeads. The carboxyl functionalization of the polymer provided the means for coating the beads with polyethylene glycol (PEG) with different molecular weight. Under gravitational force, the microbeads settled on glass surfaces with similar polymer coatings. We examined the efficacy of removing the beads from the glass surfaces by applying a pulling force of ~1.2 pN. The percent beads remaining on the surface after applying the pulling force for approximately 5 s served as an indication of the adhesion propensity. Coating of PEG with molecular weight ranging between 3 and 10 kDa was essential for suppressing the adhesion. For the particular substrates, surface chemistry and aqueous media we used, coatings of 5 kDa manifested optimal suppression of adhesion: that is, only 3% of the microbeads remained on the surface after applying the pulling magnetic force. When either the glass or the beads were not PEGylated, the adhesion between them was substantial. Addition of a noncharged surfactant, TWEEN, above its critical micelle concentrations (CMCs) suppressed the adhesion between noncoated substrates. The extent of this surfactant-induced improvement of the adhesion suppression, however, did not exceed the quality of preventing the adhesion that we attained by PEGylating both substrates. In addition, the use of surfactants did not significantly improve the suppression of bead-surface adhesion when both substrates were PEGylated. These findings suggest that such surfactant additives tend to be redundant and that covalently grafted coatings of PEGs with selected chain lengths provide sufficient suppression of nonspecific interfacial interactions.

  19. The magnetostriction in a superconductor-magnet system under non-uniform magnetic field

    NASA Astrophysics Data System (ADS)

    Li, Xueyi; Jiang, Lang; Wu, Hao; Gao, Zhiwen

    2017-03-01

    This paper describes a numerical model to examine the magnetostriction of bulk high-temperature superconductor (HTS) under non-uniform magnetic field in conjunction with finite element analysis. Through this model, the magnetostriction of homogeneous and nonhomogeneous HTS can be implemented under non-uniform magnetic field. Further, the effects of critical current density, applied field frequency and amplitude are also considered. The computational study can provide a fundamental mechanistic understanding the effects of non-uniform magnetic field on magnetostriction of HTS.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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).

  5. Strategies to Minimize Adhesions to Intraperitoneally Placed Mesh in Laparoscopic Ventral Hernia Repair

    PubMed Central

    Saliba, Lucia; Chandratnam, Edward; Turingan, Isidro; Hawthorne, Wayne

    2012-01-01

    Introduction: Adhesions to mesh/tacks in laparoscopic ventral hernia repair are often cited as reasons not to adopt its evidence-based superiority over conventional open methods. This pilot study assessed the occurrence of adhesions to full-sized Polypropylene and Gore-tex DualMesh Plus meshes and the possibility for adhesion prevention using fibrin sealant. Methods: Two 10-cm to 15-cm pieces of mesh were placed and fixed laparoscopically in pigs (25kg to 55kg). Group I: 2 animals with Polypropylene mesh on one side and DualMesh on other side. Group II: 2 animals with DualMesh on each side with fibrin sealant applied to the periphery of mesh and staples to one side. Group III: 1 animal with 2 pieces of Polypropylene mesh with fibrin sealant applied to the entire mesh. All animals underwent laparoscopy 3 months later to assess the extent of adhesions, and full-thickness specimens were removed for histological evaluation. Results: More Polypropylene mesh was involved in adhesions than DualMesh. However, with the DualMesh involved in adhesions, more of the surface area was involved in forming adhesions than with Polypropylene mesh. None of the implanted DualMesh had visceral adhesions, while 2 out of 3 Polypropylene meshes had adhesions to both the liver and spleen but none to the bowel. Implanted Polypropylene mesh with fibrin sealant had no adhesions. DualMesh had shrunk more significantly than Polypropylene mesh. Histological evaluation showed absence of acute inflammatory response, significantly more chronic inflammatory response to DualMesh compared to Polypropylene and complete mesothelialization with both meshes. There was extensive collagen deposition between Polypropylene mesh fibers, while fibrosis occurred on both sides of DualMesh with synovial metaplasia over its peritoneal surface akin to encapsulation. Conclusions: DualMesh caused fewer omental and visceral adhesions than Polypropylene mesh did. Fibrin sealant eliminated adhesions to DualMesh and

  6. Uniform Limit Theorems for Synchronous Processes with Applications to Queues

    DTIC Science & Technology

    1989-10-01

    first moment. In the present paper we investi gate conditions under which the Cesaro averaged functionals ;(f) 1- jfoE((6,X))dj converge uniformly...Proposition 3.1 both apply to positive HRMP’s. So, for example, given any initial state Z 0 = :, it follows that the Cesaro averaged measures (A) 1! 7foEIA o...collection of measures (see Theorem 2.1 of [41)). Continuing in the spirit of Cesaro convergence we have Proposition 4.1. If Z is a positive HRMP with

  7. Uniform Invariance Principle and Synchronization. Robustness with Respect to Parameter Variation

    NASA Astrophysics Data System (ADS)

    Rodrigues, H. M.; Alberto, L. F. C.; Bretas, N. G.

    2001-01-01

    The objective of this work is to obtain uniform estimates, with respect to parameters, of the attractor and of the basin of attraction of a dynamical system and to apply these results to analyze the roughness of the synchronization of two subsystems. These estimates are obtained through a uniform version of the invariance principle of La Salle which is stated and proved in this work.

  8. 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

  9. Applied Nanotoxicology

    PubMed Central

    Hobson, David W.; Roberts, Stephen M.; Shvedova, Anna A.; Warheit, David B.; Hinkley, Georgia K.; Guy, Robin C.

    2016-01-01

    Nanomaterials, including nanoparticles and nanoobjects, are being incorporated into everyday products at an increasing rate. These products include consumer products of interest to toxicologists such as pharmaceuticals, cosmetics, food, food packaging, household products, and so on. The manufacturing of products containing or utilizing nanomaterials in their composition may also present potential toxicologic concerns in the workplace. The molecular complexity and composition of these nanomaterials are ever increasing, and the means and methods being applied to characterize and perform useful toxicologic assessments are rapidly advancing. This article includes presentations by experienced toxicologists in the nanotoxicology community who are focused on the applied aspect of the discipline toward supporting state of the art toxicologic assessments for food products and packaging, pharmaceuticals and medical devices, inhaled nanoparticle and gastrointestinal exposures, and addressing occupational safety and health issues and concerns. This symposium overview article summarizes 5 talks that were presented at the 35th Annual meeting of the American College of Toxicology on the subject of “Applied Nanotechnology.” PMID:26957538

  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. Design of Novel Mixer and Applicator for Two-Component Surgical Adhesives

    PubMed Central

    Go, Kevin; Kim, Yeong; Lee, Andy H.; Staricha, Kelly; Messersmith, Phillip; Glucksberg, Matthew

    2015-01-01

    Current mixer and applicator devices on the market are not able to properly and efficiently mix two-component surgical adhesives in small volumes necessary to achieve economic viability. Furthermore, in these devices a significant amount of adhesive is wasted during the application process, as material within the dead space of the mixing chamber must be discarded. We have designed and demonstrated a new active mixer and applicator system capable of rapidly and efficiently mixing two components of an adhesive and applying it to the surgical site. Recently, Messersmith et al. have developed a tissue adhesive inspired by the mussel byssus and have shown that it is effective as a surgical sealant, and is especially suited for wet environments such as in fetal surgery. Like some other tissue sealants, this one requires that two components of differing viscosities be thoroughly mixed within a specified and short time period. Through a combination of compression and shear testing, we demonstrated that our device could effectively mix the adhesive developed by Messersmith et al. and improve its shear strength to significantly higher values than what has been reported for vortex mixing. Overall, our mixer and applicator system not only has potential applications in mixing and applying various adhesives in multiple surgical fields but also makes this particular adhesive viable for clinical use. PMID:26421090

  13. Smart Actuators and Adhesives for Reconfigurable Matter.

    PubMed

    Ko, Hyunhyub; Javey, Ali

    2017-03-06

    based on enhanced solvent diffusion rate through the porous or structured hydrogel materials, electrostatic repulsion between cofacial electrolyte nanosheets, and photothermal actuation are discussed. Second, the ability to reconfigure programmable matters into a variety of complex structures is beneficial for the use of reconfigurable matter in diverse applications. For the reconfiguration of planar 2D structures into complex 3D structures, asymmetric and multidirectional stress should be applied. In this regard, local hinges with stimuli-responsive stiffness, multilayer laminations with different responsiveness in individual layers, and origami and kirigami assembly approaches are reviewed. Third, multistimuli responsiveness will be required for the efficient reconfiguration of complex programmable matter in response to user-defined stimulus under different chemical and physical environments. In addition, with multistimuli responsiveness, the reconfigured shape can be temporarily affixed by one signal and disassembled by another signal at a user-defined location and time. Photoactuation depending on the chirality of carbon nanotubes and composite gels with different responsiveness will be discussed. Finally, the development of smart adhesives with on-demand adhesion strength is critically required to maintain the robust reconfigurable shapes and for the switching on/off of the binding between components or with target objects. Among various connectors and adhesives, thermoresponsive nanowire connectors, octopus-inspired smart adhesives, and elastomeric tiles with soft joints are described due to their potential applications in joints of deformable 3D structures and smart gripping systems.

  14. Time-dependent hygrothermomechanical properties of a structural adhesive

    NASA Astrophysics Data System (ADS)

    You, Jianmin

    This research determines the effect of hygro-thermal environment and strain rate on the tensile properties and develop a method to determine the long-term durability of structural adhesive FM300k. Topics related to structural adhesives are reviewed, including development history, classification, application, and chemical structure. Most high performance structural adhesives are epoxies with viscoelastic behavior which is greatly affected by relative humidity (RH), temperature, and strain rate. Theories for modeling the viscoelastic materials are also investigated. A testing system was developed with which the time-dependent hygro-thermo-mechanical properties of structural adhesives can be measured. This effort consists of building tensiometers and environmental chambers, controlling RH and temperature, preparing and conditioning specimens, applying displacements with a computer-controlled stepper motor, developing C++ and LabVIEW programs, and acquiring data automatically. Tests performed in the present study include thermal expansion and moisture swelling, tensile creep and stress relaxation, monotonic tensile tests, and adiabatic cooling. Tensile stress-strain curves are measured at different RHs (15%, 50% and 85%), temperature (--15°, 30° and 50°C) and strain rate (10-2, 10-4, 10-6 and 10 -8 s-1) to determine the effects of batch, loading method, environment, strain rate, and adhesive. Results from the five series of tests show very good correlation and indicate the excellent performance, high reliability, and reproducibility of the testing system developed in the present study. Mathematical models of creep and stress relaxation are used to predict the long-term durability of structural adhesive FM 300k. The concept of a master stress-strain curve for polymeric materials is introduced based on the results of the monotonic tensile tests. Using a master stress-strain curve, the long-term hygro-thermo-mechanical properties of structural adhesive FM300k can be

  15. Temperature uniformity in hyperthermal tumor therapy

    NASA Technical Reports Server (NTRS)

    Harrison, G. H.; Robinson, J. E.; Samaras, G. M.

    1978-01-01

    Mouse mammary tumors heated by water bath or by microwave-induced hyperthermia exhibit a response that varies sharply with treatment temperature; therefore, uniform heating of the tumor is essential to quantitate the biological response as a function of temperature. C3H tumors implanted on the mouse flank were easily heated to uniformities within 0.1 C by using water baths. Cold spots up to 1 C below the desired treatment temperature were observed in the same tumors implanted on the hind leg. These cold spots were attributed to cooling by major blood vessels near the tumor. In this case temperature uniformity was achieved by the deposition of 2450 MHz microwave energy into the tumor volume by using parallel-opposed applicators.

  16. Nonspherical LED packaging lens for uniformity improvement

    NASA Astrophysics Data System (ADS)

    Chang, Yu-Cheng; Ou, Chung-Jen; Tsai, Yu-Sheng; Juang, Fuh-Shyang

    2009-05-01

    Light emitting diode (LED) has more advantages compared with a traditional incandescent light bulb and a fluorescent lamp, such as small size, low quantity of heat, long life, low power consumption, fast response, plain packaging and ease of develop ment of a frivolous short product. A methodology is proposed to improve the uniformity of the LED illumination system. As a light source in a backlight unit (BLU), the requirement for optical characteristics of a LED is different from highly directional conventional ones. New diffused-type LEDs need to be developed to fulfill the requirement of the BLU industry. A non-spherical lens is designed to optimize uniformity, and a great improvement in uniformity from 28.4 to 64% is demonstrated. In the future, it may used in an LED display to improve the unevenness of illumination.

  17. Uniform colloidal zinc compounds of various morphologies

    SciTech Connect

    Castellano, M.; Matijevic, E. )

    1989-02-01

    The preparation of finely dispersed zinc compounds consisting of uniform particles is described. Aging at elevated temperatures ({approx} 90{degree}C) of aqueous solutions of zinc nitrate or zinc chloride in the presence of urea resulted in precipitation of uniform rodlike basic zinc carbonate particles. These solids show x-ray characteristics of crystalline hydrozincite. In the presence of sulfate ions amorphous spherical particles of narrow size distribution of the same chemical composition are generated. On calcination both kinds of solids change to zinc oxide yet retain the original shape. In the presence of NaH{sub 2}PO{sub 4} and urea, aqueous zinc salt solutions on aging yield rather uniform amorphous spherical zinc basic phosphate particles, which on calcination lose water.

  18. 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.

  19. Elastic stability of non-uniform columns

    NASA Astrophysics Data System (ADS)

    Lee, S. Y.; Kuo, Y. H.

    1991-07-01

    A simple and efficient method is proposed to investigate the elastic stability of three different tapered columns subjected to uniformly distributed follower forces. The influences of the boundary conditions and taper ratio on critical buckling loads are investigated. The critical buckling loads of columns of rectangular cross section with constant depth and linearly varied width ( T1), constant width and linearly varied depth ( T2) and double taper ( T3) are investigated. Among the three different non-uniform columns considered, taper ratio has the greatest influence on the critical buckling load of column T3 and the lowest influence on that of column T1. The types of instability mechanisms for hinged-hinged and cantilever non-uniform columns are divergence and flutter respectively. However, for clamped-hinged and clamped-clamped non-uniform columns, the type of instability mechanism for column T1 is divergence, while that for columns T2 and T3 is divergence only when the taper ratio of the columns is greater than certain critical values and flutter for the rest value of taper ratio. When the type of instability mechanism changes from divergence to flutter, there is a finite jump for the critical buckling load. The influence of taper ratio on the elastic stability of cantilever column T3 is very sensitive for small values of the taper ratio and there also exist some discontinieties in the critical buckling loads of flutter instability. For a hinged-hinged non-uniform column ( T2 or T3) with a rotational spring at the left end of the column, when the taper ratio is less than the critical value the instability mechanism changes from divergence to flutter as the rotational spring constant is increased. For a clamped-elastically supported non-uniform column, when the taper ratio is greater than the critical value the instability mechanism changes from flutter to divergence as the translational spring constant is increased.

  20. A nano-cheese-cutter to directly measure interfacial adhesion of freestanding nano-fibers

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Najem, Johnny F.; Wong, Shing-Chung; Wan, Kai-tak

    2012-01-01

    A nano-cheese-cutter is fabricated to directly measure the adhesion between two freestanding nano-fibers. A single electrospun fiber is attached to the free end of an atomic force microscope cantilever, while a similar fiber is similarly prepared on a mica substrate in an orthogonal direction. External load is applied to deform the two fibers into complementary V-shapes, and the force measurement allows the elastic modulus to be determined. At a critical tensile load, "pull-off" occurs when the adhering fibers spontaneously detach from each other, yielding the interfacial adhesion energy. Loading-unloading cycles are performed to investigate repeated adhesion-detachment and surface degradation.

  1. Modeling and design optimization of adhesion between surfaces at the microscale.

    SciTech Connect

    Sylves, Kevin T.

    2008-08-01

    This research applies design optimization techniques to structures in adhesive contact where the dominant adhesive mechanism is the van der Waals force. Interface finite elements are developed for domains discretized by beam elements, quadrilateral elements or triangular shell elements. Example analysis problems comparing finite element results to analytical solutions are presented. These examples are then optimized, where the objective is matching a force-displacement relationship and the optimization variables are the interface element energy of adhesion or the width of beam elements in the structure. Several parameter studies are conducted and discussed.

  2. Uniform color space is not homogeneous

    NASA Astrophysics Data System (ADS)

    Kuehni, Rolf G.

    2002-06-01

    Historical data of chroma scaling and hue scaling are compared and evidence is shown that we do not have a reliable basis in either case. Several data sets indicate explicitly or implicitly that the number of constant sized hue differences between unique hues as well as in the quadrants of the a*, b* diagram differs making what is commonly regarded as uniform color space inhomogeneous. This problem is also shown to affect the OSA-UCS space. A Euclidean uniform psychological or psychophysical color space appears to be impossible.

  3. An in vitro study of the bond strength of five adhesives used for vinyl polysiloxane impression materials and tray materials.

    PubMed

    Kumar, Surender; Gandhi, Udey Vir; Banerjee, Saurav

    2014-03-01

    Although stock trays often provide mechanical retention for elastomeric impression materials, manufacturers typically recommend the use of an adhesive, whether a stock or custom tray is used. The mention of the bond strength on the adhesive packaging is not available, therefore the clinician has no idea whatsoever of the ideal adhesive. The aim of this study was to evaluate the bond strength of three vinyl polysiloxane (VPS) materials, one with a poly(methyl methacrylate) autopolymerizing (PMMA) specimen and another with a light-polymerizing tray material (VLC), using the adhesive recommended by the manufacturer of the impression material, and two universal adhesives. A total of ninety specimens (15 × 15 × 20 mm) were used, 45 specimens were made in PMMA and rest 45 was made in VLC. Five paint-on adhesives (Coltene, Caulk, 3M, universal Zhermack and universal GC) were applied. Three impression materials, Affinis, Reprosil, and 3M, were mixed and injected into a perforated poly vinyl chloride cylinder. Tray specimens were positioned against the open cylinder end in contact with the VPS material. Tensile strength tests were conducted until adhesive separation failure. Mean values and standard errors of the adhesive strength were recorded in MPa for each material combination. GC paint-on universal adhesive provided significantly higher adhesive strength values.

  4. Marginal sealing durability of two contemporary self-etch adhesives.

    PubMed

    Khoroushi, Maryam; Mansoori, Mahsa

    2012-01-01

    Introduction. Sealing abilities of two self-etch adhesives were evaluated after two aging processes: storage in water and thermocycling. Materials and Methods. Cl V cavities were prepared on the buccal and lingual aspects of 48 human premolars, with cervical margins 1 mm below the CEJ. Clearfil Protect Bond (CPB) and BeautiBond (BB) (two-step and one-step self-etch adhesives, resp.) were applied, each to half of the cavities and restored with composite resin. Each group was randomly subdivided into 4 subgroups (n = 12) and evaluated for dye penetration after 24 hours, after 3000 thermocycling rounds, after a 6-month water storage, and after 3000 thermocycling rounds plus 6-month water storage, respectively. Data was analyzed using SPSS 11.5 and Kruskal-Wallis and Mann-Whitney U tests (α = 0.05). Results. There were no significant differences in enamel and dentin microleakage between the adhesives (P = 0.683; P = 0.154). Furthermore, no significant differences were observed in enamel microleakage of each one of CPB and BB (P = 0.061 and P = 0.318, resp.). However, significant decrease was observed in subgroups 3 and 4 (P = 0.001) for CPB dentinal margins. Conclusion. In this study, limited aging procedures had no influence on marginal integrity of composite resin restorations bonded with self-etch adhesives of CPB and BB. Furthermore, CPB dentinal sealing improved after aging.

  5. Marginal Sealing Durability of Two Contemporary Self-Etch Adhesives

    PubMed Central

    Khoroushi, Maryam; Mansoori, Mahsa

    2012-01-01

    Introduction. Sealing abilities of two self-etch adhesives were evaluated after two aging processes: storage in water and thermocycling. Materials and Methods. Cl V cavities were prepared on the buccal and lingual aspects of 48 human premolars, with cervical margins 1 mm below the CEJ. Clearfil Protect Bond (CPB) and BeautiBond (BB) (two-step and one-step self-etch adhesives, resp.) were applied, each to half of the cavities and restored with composite resin. Each group was randomly subdivided into 4 subgroups (n = 12) and evaluated for dye penetration after 24 hours, after 3000 thermocycling rounds, after a 6-month water storage, and after 3000 thermocycling rounds plus 6-month water storage, respectively. Data was analyzed using SPSS 11.5 and Kruskal-Wallis and Mann-Whitney U tests (α = 0.05). Results. There were no significant differences in enamel and dentin microleakage between the adhesives (P = 0.683; P = 0.154). Furthermore, no significant differences were observed in enamel microleakage of each one of CPB and BB (P = 0.061 and P = 0.318, resp.). However, significant decrease was observed in subgroups 3 and 4 (P = 0.001) for CPB dentinal margins. Conclusion. In this study, limited aging procedures had no influence on marginal integrity of composite resin restorations bonded with self-etch adhesives of CPB and BB. Furthermore, CPB dentinal sealing improved after aging. PMID:22611501

  6. Multiparticle adhesive dynamics. Interactions between stably rolling cells.

    PubMed Central

    King, M R; Hammer, D A

    2001-01-01

    A novel numerical simulation of adhesive particles (cells) reversibly interacting with an adhesive surface under flow is presented. Particle--particle and particle--wall hydrodynamic interactions in low Reynolds number Couette flow are calculated using a boundary element method that solves an integral representation of the Stokes equation. Molecular bonds between surfaces are modeled as linear springs and stochastically formed and broken according to postulated descriptions of force-dependent kinetics. The resulting simulation, Multiparticle Adhesive Dynamics, is applied to the problem of selectin-mediated rolling of hard spheres coated with leukocyte adhesion molecules (cell-free system). Simulation results are compared to flow chamber experiments performed with carbohydrate-coated spherical beads rolling on P-selectin. Good agreement is found between theory and experiment, with the main observation being a decrease in rolling velocity with increasing concentration of rolling cells or increasing proximity between rolling cells. Pause times are found to increase and deviation motion is found to decrease as pairs of rolling cells become closer together or align with the flow. PMID:11463626

  7. Effect of pre-tension on the peeling behavior of a bio-inspired nano-film and a hierarchical adhesive structure

    NASA Astrophysics Data System (ADS)

    Peng, Zhilong; Chen, Shaohua

    2012-10-01

    Inspired by the reversible adhesion behaviors of geckos, the effects of pre-tension in a bio-inspired nano-film and a hierarchical structure on adhesion are studied theoretically. In the case with a uniformly distributing pre-tension in a spatula-like nano-film under peeling, a closed-form solution to a critical peeling angle is derived, below or above which the peel-off force is enhanced or reduced, respectively, compared with the case without pre-tension. The effects of a non-uniformly distributing pre-tension on adhesion are further investigated for both a spatula-like nano-film and a hierarchical structure-like gecko's seta. Compared with the case without pre-tension, the pre-tension, no matter uniform or non-uniform, can increase the adhesion force not only for the spatula-like nano-film but also for the hierarchical structure at a small peeling angle, while decrease it at a relatively large peeling angle. Furthermore, if the pre-tension is large enough, the effective adhesion energy of a hierarchical structure tends to vanish at a critical peeling angle, which results in spontaneous detachment of the hierarchical structure from the substrate. The present theoretical predictions can not only give some explanations on the existing experimental observation that gecko's seta always detaches at a specific angle and no apparent adhesion force can be detected above the critical angle but also provide a deep understanding for the reversible adhesion mechanism of geckos and be helpful to the design of biomimetic reversible adhesives.

  8. Effect of hyaluronic acid on postoperative intraperitoneal adhesion formation and reformation in the rat model

    SciTech Connect

    Urman, B.; Gomel, V. )

    1991-09-01

    The local application of 0.25% or 0.4% HA before the induction of a measured laser injury on the rat uterine horn was associated with a significant reduction (P less than 0.05) in postoperative IP adhesions when compared with the group of animals pretreated with the diluent vehicle PBS or received no pretreatment. However, 0.4% HA, when applied in a similar manner, was ineffective in reducing reformation of adhesions after microsurgical adhesiolysis.

  9. A comparison of soil hydrothermal properties in zonal and uniform tillage systems across the northern U.S. corn belt

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A primary goal of tillage is to improve seedbed temperature and moisture (hydrothermal) conditions to maximise crop emergence and development. Uniform tillage practices (e.g. conventional tillage and no-till) apply management uniformly across a field. Conventional tillage attempts to optimise sprin...

  10. Comparison of two leading uniform theories of edge diffraction with the exact uniform asymptotic solution

    NASA Technical Reports Server (NTRS)

    Boersma, J.; Rahmat-Samii, Y.

    1980-01-01

    The diffraction of an arbitrary cylindrical wave by a half-plane has been treated by Rahmat-Samii and Mittra who used a spectral domain approach. In this paper, their exact solution for the total field is expressed in terms of a new integral representation. For large wave number k, two rigorous procedures are described for the exact uniform asymptotic expansion of the total field solution. The uniform expansions obtained are valid in the entire space, including transition regions around the shadow boundaries. The final results are compared with the formulations of two leading uniform theories of edge diffraction, namely, the uniform asymptotic theory and the uniform theory of diffraction. Some unique observations and conclusions are made in relating the two theories.

  11. 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.

  12. Uniforms: Are They a Good Fit?

    ERIC Educational Resources Information Center

    Boutelle, Marsha

    2008-01-01

    In an era where some parents seem unwilling or unable to draw the "clothes" line with their children, where pop culture influences kids' clothing choices as never before, and school safety--including gang violence--is at the top of everyone's minds, school uniforms and dress codes can play a significant role. What that role should be,…

  13. Electroformed screens with uniform hole size

    NASA Technical Reports Server (NTRS)

    Schaer, G. R.

    1968-01-01

    Efficient method electroforms fine-mesh nickel screens, or plagues, with uniform hole size and accurate spacing between holes. An electroformed nickel mandrel has nonconducting silicone rubber projections that duplicate the desired hole size and shape in the finished nickel screen.

  14. Spatial uniformity measurement of SAW convolvers

    NASA Astrophysics Data System (ADS)

    Selviah, D. R.; Warne, D. H.; Morgan, D. P.

    1982-09-01

    For correlation of coded waveforms, the nonlinear interactive process in a SAW convolver should ideally give an amplitude and phase independent of position. A new experimental method of measuring this spatial uniformity used CW test waveforms and gave a resolution of 25 ns - a considerably higher resolution than previously attained.

  15. Mandatory School Uniforms and Freedom of Expression

    ERIC Educational Resources Information Center

    Vopat, Mark C.

    2010-01-01

    On 10 December 2007 the Akron City School Board--following the precedent set by many school systems across the United States and the world--instituted a policy of mandatory school uniforms for all students in grades K-8. The measure was met with mixed reviews. While many parents supported the measure, a small group of parents from a selective,…

  16. School Uniforms in Urban Public High Schools

    ERIC Educational Resources Information Center

    Draa, Virginia Ann Bendel

    2005-01-01

    The purpose of this study was to determine whether or not the implementation of a mandatory uniform policy in urban public high schools improved school performance measures at the building level for rates of attendance, graduation, academic proficiency, and student conduct as measured by rates of suspensions and expulsions. Sixty-four secondary…

  17. School Uniform Revisited: Procedure, Pressure and Equality

    ERIC Educational Resources Information Center

    Carney, Damian; Sinclair, Adele

    2006-01-01

    The House of Lords' decision in "R. (on the application of Begum) v. The Headteacher and Governors of Denbigh High School" considered whether a particular school uniform policy infringed a student's right to manifest her religion under Article 9. This paper analyses the content of this decision, and explores how schools should approach…

  18. Is Curriculum Quality Uniform? Evidence from Florida

    ERIC Educational Resources Information Center

    Bhatt, Rachana; Koedel, Cory; Lehmann, Douglas

    2013-01-01

    We construct a large panel dataset of schools and districts in Florida to evaluate curricular effectiveness in elementary mathematics. A key innovation of our study is that we allow for curriculum quality to be non-uniform across various mathematics subtopics. We find evidence of variability in curricular effectiveness across different subtopics…

  19. MODERATOR ELEMENTS FOR UNIFORM POWER NUCLEAR REACTOR

    DOEpatents

    Balent, R.

    1963-03-12

    This patent describes a method of obtaining a flatter flux and more uniform power generation across the core of a nuclear reactor. The method comprises using moderator elements having differing moderating strength. The elements have an increasing amount of the better moderating material as a function of radial and/or axial distance from the reactor core center. (AEC)

  20. METHOD OF OBTAINING UNIFORM COATINGS ON GRAPHITE

    DOEpatents

    Campbell, I.E.

    1961-04-01

    A method is given for obtaining uniform carbide coatings on graphite bodies. According to the invention a metallic halide in vapor form is passed over the graphite body under such conditions of temperature and pressure that the halide reacts with the graphite to form a coating of the metal carbide on the surface of the graphite.