Science.gov

Sample records for pressure sensitive adhesives

  1. 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.

  2. UV curable pressure sensitive adhesives

    SciTech Connect

    Glotfelter, C.A.

    1995-12-01

    Pressure sensitive adhesives (PSA`s) have become a ubiquitous element in our society, so much so, that the relative status of a society can be determined by the per capita consumption of PSA`s. We discuss new monomers as components of PSA formulations which enable adhesion to be achieved on a variety of substrates. Since solventless coating systems are desirable, the UV PSA market is of utmost importance to meeting the strict environmental guidelines now being imposed worldwide. In addition, highly ethoxylated monomers have shown promise in water dispersed PSA formulations, and a self-emulsifying acrylate monomer has been developed to offer dispersive abilities without using traditional emulsifying agents. This talk will focus on the effects of the materials described on properties of adhesive strength and shear strength in UV PSA formulations.

  3. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  4. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  5. New pressure-sensitive silicone adhesive

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  6. Contribution from pressure-sensitive adhesives

    NASA Astrophysics Data System (ADS)

    Cunningham, Gilbert

    1996-03-01

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

  7. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Pressure-sensitive adhesives. 175.125 Section 175...) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS OF COATINGS Substances for Use Only as Components of Adhesives § 175.125 Pressure-sensitive adhesives....

  8. Development of Screenable Pressure Sensitive Adhesives

    SciTech Connect

    Steven J. Severtson

    2003-11-29

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

  9. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Substances for Use Only as Components of Adhesives § 175.125 Pressure-sensitive adhesives. Pressure-sensitive... accordance with a prior sanction or approval. (3) Color additives listed for use in or on food in parts 73... with isobutylene so that the butyl content of the final product is not less than 18 percent, for use...

  10. Development of Recycling Compatible Pressure-Sensitive Adhesives and Coatings

    SciTech Connect

    Steven J. Severtson

    2010-02-15

    The objective of this project was the design of new water-based pressure-sensitive adhesive (PSA) products and coatings engineered for enhanced removal during the processing of recycled fiber. Research included the formulation, characterization, and performance measurements of new screenable coatings, testing of modified paper and board substrates and the design of test methods to characterize the inhibition of adhesive and coating fragmentation and relative removal efficiencies of developed formulations. This project was operated under the requirements that included commercially viable approaches be the focus, that findings be published in the open literature and that new strategies could not require changes in the methods and equipment used to produce PSA and PS labels or in the recycling process. The industrial partners benefited through the building of expertise in their company that they would not, and likely could not, have pursued if it had not been for the partnership. Results of research on water-based PSAs clearly identifies which PSA and paper facestock properties govern the fragmentation of the adhesive and provide multiple strategies for making (pressure-sensitive) PS labels for which the PSA is removed at very high efficiencies from recycling operations. The application of these results has led to the identification of several commercial products in Franklin International’s (industrial partner) product line that are recycling compatible. Several new formulations were also designed and are currently being scaled-up. Work on recycling compatible barrier coatings for corrugated containers examined the reinforcement of coatings using a small amount of exfoliated organically modified montmorillonite (OMMT). These OMMT/paraffin wax nanocomposites demonstrated significantly improved mechanical properties. Paraffin waxes containing clay were found to have significantly higher Young’s moduli and yield stress relative to the wax matrix, but the most

  11. Structure and macroscopic tackiness of ultrathin pressure sensitive adhesive films.

    PubMed

    Diethert, Alexander; Körstgens, Volker; Magerl, David; Ecker, Katharina; Perlich, Jan; Roth, Stephan V; Müller-Buschbaum, Peter

    2012-08-01

    Ultrathin layers of the statistical copolymer P(nBA-stat-MA) with a majority of n-butyl acrylate (nBA) and a minority of methyl acrylate (MA) are characterized with respect to the film morphology and the mechanical response in a probe tack test. The probed copolymer can be regarded as a model system of a pressure sensitive adhesive (PSA). The films are prepared by spin-coating which enables an easy thickness control via the polymer concentration of the solution. The film thickness is determined with x-ray reflectivity (XRR) and white light interferometry (WLI). Grazing incidence small angle x-ray scattering (GISAXS) provides detailed and statistically significant information about the film morphology. Two types of lateral structures are identified and no strong correlation of these structures with the PSA film thickness is observed. In contrast, prominent parameters of the probe tack test, such as the stress maximum and the tack energy, exhibit an exponential dependence on the film thickness. PMID:22817560

  12. Pressure sensitive microparticle adhesion through biomimicry of the pollen-stigma interaction.

    PubMed

    Lin, Haisheng; Qu, Zihao; Meredith, J Carson

    2016-03-21

    Many soft biomimetic synthetic adhesives, optimized to support macroscopic masses (∼kg), have been inspired by geckos, insects and other animals. Far less work has investigated bioinspired adhesion that is tuned to micro- and nano-scale sizes and forces. However, such adhesive forces are extremely important in the adhesion of micro- and nanoparticles to surfaces, relevant to a wide range of industrial and biological systems. Pollens, whose adhesion is critical to plant reproduction, are an evolutionary-optimized system for biomimicry to engineer tunable adhesion between particles and micro-patterned soft matter surfaces. In addition, the adhesion of pollen particles is relevant to topics as varied as pollinator ecology, transport of allergens, and atmospheric phenomena. We report the first observation of structurally-derived pressure-sensitive adhesion of a microparticle by using the sunflower pollen and stigma surfaces as a model. This strong, pressure-sensitive adhesion results from interlocking between the pollen's conical spines and the stigma's receptive papillae. Inspired by this behavior, we fabricated synthetic polymeric patterned surfaces that mimic the stigma surface's receptivity to pollen. These soft mimics allow the magnitude of the pressure-sensitive response to be tuned by adjusting the size and spacing of surface features. These results provide an important new insight for soft material adhesion based on bio-inspired principles, namely that ornamented microparticles and micro-patterned surfaces can be designed with complementarity that enable a tunable, pressure-sensitive adhesion on the microparticle size and length scale. PMID:26883733

  13. Pressure-sensitive adhesives for transdermal drug delivery systems.

    PubMed

    Tan; Pfister

    1999-02-01

    Adhesives are a critical component in transdermal drug delivery (TDD) devices. In addition to the usual requirements of functional adhesive properties, adhesives for TDD applications must have good biocompatibility with the skin, chemical compatibility with the drug, various components of the formulation, and provide consistent, effective delivery of the drug. This review discusses the three most commonly used adhesives (polyisobutylenes, polyacrylates and silicones) in TDD devices, and provides an update on recently introduced TDD products and recent developments of new adhesives. PMID:10234208

  14. Bond strength of pressure sensitive adhesives for CFRP aluminium-alloy hybrid beams under impact loading

    NASA Astrophysics Data System (ADS)

    Sato, C.

    2003-09-01

    This paper discusses the impact absorbing capabilities of CFRP aluminium-alloy hybrid beams bonded with double-coated pressure sensitive adhesive tapes. Two sorts of double-coated adhesive tapes (VHB and SBT, 3M) were used in experiments. The strength and absorbed energy of the beams under impact loading were measured using an instrumented Charpy tester. Using the beams having the different adhesive tapes and the CFRP of different length, the variations of the strength and the absorbed energy were investigated. The beams bonded with VHB showed sufficient strength and absorbed energy. SBT showed also great capability of absorbing impact energy.

  15. Polymer-Solid Interface Connectivity and Adhesion: Design of a Pressure Sensitive Adhesive

    NASA Astrophysics Data System (ADS)

    Bunker, Shana P.; Wool, Richard P.

    2007-03-01

    Adhesion at polymer-solid interfaces was explored for a new bio-based PSA in terms of sticker groups φX on the polymer, receptor groups φY on the solid and the strength of the X-Y acid-base interaction, χ. The polymer-solid interface models of Gong, Lee and Wool were extended with new percolation models of entanglements and interface strength to determine the optimal sticker group concentration φ*X. For the general case where φY and χ are constant, it is predicted that when φX<φ*X, the peel strength behaves as G1c˜φX/φ*X and the locus of failure is adhesive between the polymer and the solid. However, when φX>φ*X, failure occurs cohesively in a polymer-polymer interface adjacent to the solid and the strength decreases as G1c˜φ*X/φX. The switch from adhesive to cohesive failure can be understood in terms of the changes in the chain conformations of the adhered chains and their decreasing interpenetration X with the bulk chains, via X˜1/r, where r = χφXφY. The optimal value of φX which maximizes the adhesion and determines the mode of failure is given by φ*X 0.07/C, and for typical values of the characteristic ratio C in the range 7-10, φ*X 1% mole fraction, corresponding to about 2 sticker groups per critical entanglement length Mc. Supported by USDA

  16. Influence of large strain rheology on the peeling performances of Pressure Sensitive Adhesives

    NASA Astrophysics Data System (ADS)

    Villey, Richard; Ciccotti, Matteo; Creton, Costantino; Cortet, Pierre-Philippe; Yarusso, David J.

    2015-03-01

    The dependence of adhesion energy of Pressure Sensitive Adhesives (PSA) on peeling velocity reduces to a master curve using a time-temperature superposition principle, usually verified by the linear rheology of polymers. This result has guided models predicting peeling energy of PSA to consider the small strain rheology of the glue only, despite it can experience very large strains before debonding. The argument of the time-temperature superposition principle can actually also be applied to large strains and is thus not a stringent one. To clarify the role of large strain rheology during the peeling of PSA, we present experiments on commercial and custom-made tapes supplied by 3M Company. Small and large strain rheology differences are obtained by changing the glass transition temperature, the cross-linking density and the density of entanglements, yet remaining close to commercial PSA. The rheology influence is decoupled from geometrical effects, by examining the nontrivial dependence of the adhesion energy on the peeling angle. Finally, adhesion energy measurements and visualizations of the process zone, over a large range of peeling velocities, are discussed, in the perspective of building a model for the adherence considering the complete rheology of the glue.

  17. Processing Effects on Block-Copolymer Based Pressure-Sensitive Adhesives

    NASA Astrophysics Data System (ADS)

    O'Connor, A. E.; Macosko, C. W.

    2000-03-01

    The goal of this work is to investigate how the variables in the hot-melt coating process affect the microstructure and properties of pressure-sensitive adhesives based on a styrene isoprene styrene triblock copolymer. This polymer is a thermoplastic elastomer, able to be coated at high temperatures and physically crosslinked at lower temperatures. Adhesive tape samples have been made through hot-melt and solvent coating methods. Hot-melt coatings are prepared at speeds up to 110 feet/minute. Materials with the same thermal history have been coated using both methods and then tested for comparison of properties. PSA properties are strongly dependent on the time scale of application and debonding, as revealed by shear rheology data, and three types of performance tests (tack, peel, and shear holding power) are used to capture the various responses. Solvent-coated tape has superior shear strength, while hot-melt-coated tape performs better in peel tests. It is expected that the varying flow and deformation histories of the samples will lead to distinct chain orientations, while the rate of cooling of hot-melt-coated samples may influence the degree of phase separation achieved. These factors will cause the adhesive coatings to have different microstructures and therefore different properties.

  18. Tackiness of pressure-sensitive adhesives: An ultra-small-angle X-ray scattering investigation

    NASA Astrophysics Data System (ADS)

    Müller-Buschbaum, P.; Ittner, T.; Petry, W.

    2004-05-01

    The debonding of a model pressure-sensitive adhesive (PSA) poly-n-buthylacrylate is investigated by a combination of the mechanical tack test, optical microscopy and in situ ultra-small-angle X-ray scattering. From the mechanical test, macroscopic values such as force-distance curves are determined. The force-distance curve exhibits the typical non-linear behavior. With microscopy the macroscopic cavitation structure is observed. Scattering addresses the structure of the PSA on a microscopic level for the first time. As a new feature, a sub-structure of the usual optically resolvable macroscopic fibrils between the PSA surface and the probe punch is detected. The sub-structure exists over a large distance between the PSA and the probe surface and remains constant in diameter. This behavior of the sub-structure as well as the dependence of the force plateau on the film thickness are compared with theoretical predictions.

  19. Adherence performances of pressure sensitive adhesives on a model viscoelastic synthetic film: a tool for the understanding of adhesion on the human skin.

    PubMed

    Renvoise, Julien; Burlot, Delphine; Marin, Gérard; Derail, Christophe

    2009-02-23

    This work deals with the rheological behavior and adherence properties of pressure sensitive adhesive formulations dedicated to medical applications. We have developed a specific viscoelastic substrate which mimics adhesion on human skin to measure the adherence properties of PSAs when they are stuck on the human skin. By comparing peeling results of PSAs, dedicated to medical applications, stuck on human skin and on this viscoelastic substrate we show that this substrate, based on a blend of natural proteins, presents a better representation of the interactions occurring at the skin/adhesive interface than conventional substrates used for peel test (i.e. glass and steel). PMID:18992309

  20. A measurement system analysis with design of experiments: Investigation of the adhesion performance of a pressure sensitive adhesive with the probe tack test.

    PubMed

    Michaelis, Marc; Leopold, Claudia S

    2015-12-30

    The tack of a pressure sensitive adhesive (PSA) is not an inherent material property and strongly depends on the measurement conditions. Following the concept of a measurement system analysis (MSA), influencing factors of the probe tack test were investigated by a design of experiments (DoE) approach. A response surface design with 38 runs was built to evaluate the influence of detachment speed, dwell time, contact force, adhesive film thickness and API content on tack, determined as the maximum of the stress strain curve (σmax). It could be shown that all investigated factors have a significant effect on the response and that the DoE approach allowed to detect two-factorial interactions between the dwell time, the contact force, the adhesive film thickness and the API content. Surprisingly, it was found that tack increases with decreasing and not with increasing adhesive film thickness. PMID:26428630

  1. Energy Efficienct Processes for Making Tackifier Dispersions used to make Pressure Sensitive Adhesives

    SciTech Connect

    Rakesh Gupta

    2006-07-26

    The primary objective of this project was to develop an energy efficient, environmentally friendly and low cost process (compared to the current process) for making tackifier dispersions that are used to make pressure-sensitive adhesives. These adhesives are employed in applications such as self-adhesive postage stamps and disposable diapers and are made by combining the tackifier dispersion with a natural or synthetic rubber latex. The current process for tackifier dispersion manufacture begins by melting a (plastic) resin and adding water to it in order to form a water-in-oil emulsion. This is then converted to an oil-in-water emulsion by phase inversion in the presence of continuous stirring. The resulting emulsion is the tackifier dispersion, but it is not concentrated and the remaining excess water has to be transported and removed. The main barrier that has to be overcome in the development of commercial quality tackifier dispersions is the inability to directly emulsify resin in water due to the very low viscosity of water as compared to the viscosity of the molten resin. In the present research, a number of solutions were proposed to overcome this barrier, and these included use of different mixer types to directly form the emulsion from the molten resin but without going through a phase inversion, the idea of forming a solid resin-in-water suspension having the correct size and size distribution but without melting of the resin, and the development of techniques of making a colloidal powder of the resin that could be dispersed in water just prior to use. Progress was made on each of these approaches, and each was found to be feasible. The most appealing solution, though, is the last one, since it does not require melting of the resin. Also, the powder can be shipped in dry form and then mixed with water in any proportion depending on the needs of the process. This research was conducted at Argonne National Laboratory, and it was determined the new process

  2. An instrumented mixer setup for making tackifier dispersions used to make pressure-sensitive adhesives

    NASA Astrophysics Data System (ADS)

    Song, Daoyun; Zhang, Wu; Melby, Earl G.; Gupta, Rakesh K.

    2008-04-01

    Water-based pressure-sensitive adhesives (PSAs) are made by combining a tackifier dispersion and a polymer latex. During the process of making the tackifier dispersion, the system initially forms a water-in-oil emulsion, and then inverts to an oil-in-water one as more water is continuously added with constant agitation. To better understand the process, an instrumented mixer setup was constructed to simulate the manufacturing process, and agitation was provided by an inner impeller and an outer impeller. Several variables were monitored in situ. They are the electrical resistance of the emulsion, torque exerted on the inner impeller, agitation speeds of both impellers, power consumption of both impellers and the flow rate of feeding water. Our measurements showed that torque reached a maximum at phase inversion, and this was verified by direct measurements of viscosity during the process. Simultaneously electrical resistance measurements monitored the chemical changes as well as phase inversion. Experiments showed that under a certain low water feeding flow rate, there appeared to be an intermediate agitation speed at which the phase inversion occurred the earliest. This, from the industrial standpoint, is really favorable due to both time and energy efficiency. Furthermore, this intermediate agitation speed also corresponded to a better quality product. All this information may be used for optimizing this process in the future.

  3. Studies on acrylated epoxydised triglyceride resin-co-butyl methacrylate towards the development of biodegradable pressure sensitive adhesives.

    PubMed

    David, S Begila; Sathiyalekshmi, K; Gnana Raj, G Allen

    2009-12-01

    The potential chemical utility of Soya bean oil for the preparation of novel biodegradable polymeric pressure sensitive adhesive has been investigated. Epoxy resin was prepared through in situ epoxidation of Soya bean oil under controlled reaction conditions. Acrylated epoxidised triglyceride resin (AET resin) and copolymer of AET resin with butyl methacrylate were prepared and evaluated. Higher the concentration of butyl methacrylate higher is the degree of copolymerization of AET resin with butyl methacrylate. An optimum concentration of AET resin with butyl methacrylate (100 : 0.40) yields favourable shear holding time and peel strength to qualify as pressure sensitive adhesive. The candidate PSA formulation is biodegradable with antimicrobial activity against gram positive S. aureus ATCC 25923. PMID:18584126

  4. Synthesis, characterization and application of water-soluble and easily removable cationic pressure-sensitive adhesives. Quarterly technical report

    SciTech Connect

    1999-09-30

    The Institute studied the adsorption of cationic pressure-sensitive adhesive (PSA) on wood fiber, and the buildup of PSA in a closed water system during paper recycling; the results are presented. Georgia Tech worked to develop an environmentally friendly polymerization process to synthesize a novel re-dispersible PSA by co-polymerizing an oil-soluble monomer (butyl acrylate) and a cationic monomer MAEPTAC; results are presented. At the University of Georgia at Athens the project focused on the synthesis of water-soluble and easily removable cationic polymer PSAs.

  5. Development of Screenable Wax Coatings and Water-Based Pressure Sensitive Adhesives

    SciTech Connect

    2006-10-01

    This factsheet describes a research project whose goal is to design new formulations and production processes for water-based adhesives and wax coatings that can be easily screened from recycling operations.

  6. Development and production of a flame retardant, general purpose, pressure sensitive adhesive tape

    NASA Technical Reports Server (NTRS)

    Monaghan, P. B.; Doggett, R. H.

    1977-01-01

    The specification results for the finished tape properties were as follows: (1) adhesive strength (180 deg peel) on aluminum from 107 to 143 grams per centimeter (0.6 to 0.8 pounds per inch); (2) adhesive strength (180 deg peel) on stainless steel from 71 to 107 grams per centimeter (0.4 to 0.6 pounds per inch); (3) unwind resistance of 536 to 714 grams per centimeter (3 to 4 pounds per inch); (4) tensile strength minimum of 7143 grams per centimeter (40 pounds per inch); (5) elongation from 5 to 10% at break; (6) tear strength, Elmendorf from 200 to 350 grams (0.44 to 0.77 pounds); and (7) tear strength, tongue from 363 to 408 grams (0.8 to 0.9) pounds).

  7. Photon and radiowave emission from peeling pressure sensitive adhesives in air

    NASA Technical Reports Server (NTRS)

    Donaldson, E. E.; Shen, X. A.; Dickinson, J. T.

    1985-01-01

    During separation of an adhesive from a polymer substrate in air, intense bursts of photons ('phE', for photon emission) and long wavelength electromagnetic radiation ('RE', for radiowave emission), similar to those reported earlier by Deryagin, et al. (1978) have been observed. In this paper, careful measurements of the phE time distributions, as well as time correlations between bursts of phE and RE, are reported. These results support the view that patches of electrical charge produced by charge separation between dissimilar materials lead to microdischarges in and near the crack tip. The role of these discharges in producing sustained phE after the discharge has been extinguished is also discussed.

  8. Synthesis, Characterization, to application of water soluble and easily removable cationic pressure sensitive adhesives

    SciTech Connect

    Institute of Paper Science Technology

    2004-01-30

    In recent years, the world has expressed an increasing interest in the recycling of waste paper to supplement the use of virgin fiber as a way to protect the environment. Statistics show that major countries are increasing their use of recycled paper. For example, in 1991 to 1996, the U.S. increased its recovered paper utilization rate from 31% to 39%, Germany went from 50% to 60%, the UK went from 60% to 70%, France increased from 46% to 49%, and China went from 32% to 35% [1]. As recycled fiber levels and water system closures both increase, recycled product quality will need to improve in order for recycled products to compete with products made from virgin fiber [2]. The use of recycled fiber has introduced an increasing level of metal, plastic, and adhesive contamination into the papermaking process which has added to the complexity of the already overwhelming task of providing a uniform and clean recycle furnish. The most harmful of these contaminates is a mixture of adhesives and polymeric substances that are commonly known as stickies. Stickies, which enter the mill with the pulp furnish, are not easily removed from the repulper and become more difficult the further down the system they get. This can be detrimental to the final product quality. Stickies are hydrophobic, tacky, polymeric materials that are introduced into the papermaking system from a mixture of recycled fiber sources. Properties of stickies are very similar to the fibers used in papermaking, viz. size, density, hydrophobicity, and electrokinetic charge. This reduces the probability of their removal by conventional separation processes, such as screening and cleaning, which are based on such properties. Also, their physical and chemical structure allows for them to extrude through screens, attach to fibers, process equipment, wires and felts. Stickies can break down and then reagglomerate and appear at seemingly any place in the mill. When subjected to a number of factors including changes

  9. Mechanical properties of a waterborne pressure-sensitive adhesive with a percolating poly(acrylic acid)-based diblock copolymer network: effect of pH.

    PubMed

    Gurney, Robert S; Morse, Andrew; Siband, Elodie; Dupin, Damien; Armes, Steven P; Keddie, Joseph L

    2015-06-15

    Copolymerizing an acrylic acid comonomer is often beneficial for the adhesive properties of waterborne pressure-sensitive adhesives (PSAs). Here, we demonstrate a new strategy in which poly(acrylic acid) (PAA) is distributed as a percolating network within a PSA film formed from a polymer colloid. A diblock copolymer composed of PAA and poly(n-butyl acrylate) (PBA) blocks was synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization and adsorbed onto soft acrylic latex particles prior to their film formation. The thin adsorbed shells on the particles create a percolating network that raises the elastic modulus, creep resistance and tensile strength of the final film. When the film formation occurs at pH 10, ionomeric crosslinking occurs, and high tack adhesion is obtained in combination with high creep resistance. The results show that the addition of an amphiphilic PAA-b-PBA diblock copolymer (2.0 wt.%) to a soft latex provides a simple yet effective means of adjusting the mechanical and adhesive properties of the resulting composite film. PMID:25706199

  10. Influence of menthol and pressure-sensitive adhesives on the in vivo performance of membrane-moderated transdermal therapeutic system of nicardipine hydrochloride in human volunteers.

    PubMed

    Krishnaiah, Y S R; Satyanarayana, V; Bhaskar, P

    2003-05-01

    A membrane-moderated transdermal therapeutic system of nicardipine hydrochloride was developed using 2% w/w hydroxypropylcellulose (HPC) gel as a reservoir system containing 5% w/w of menthol as a penetration enhancer. The permeability flux of nicardipine hydrochloride through the ethylene vinyl acetate (EVA) copolymer membrane was found to increase with an increase in vinyl acetate content in the copolymer. The effect of various pressure-sensitive adhesives (MA-31, MA-38 or TACKWHITE A 4MED on the permeability of nicardipine hydrochloride through EVA 2825 membrane (28% w/w vinyl acetate) or EVA 2825 membrane/skin composite was also studied. The results showed that nicardipine hydrochloride permeability through EVA 2825 membrane coated with TACKWHITE A 4MED/skin composite was higher than that coated with MA-31 or MA-38. Thus, a new transdermal therapeutic system for nicardipine hydrochloride was formulated using EVA 2825 membrane coated with a pressure-sensitive adhesive TACKWHITE A 4MED, and 2% w/w HPC gel as reservoir containing 5% w/w of menthol as a penetration enhancer. In vivo studies in healthy human volunteers indicated that the TTS of nicardipine hydrochloride, designed in the present study, provided steady-state plasma concentration of the drug with minimal fluctuations for 26h with improved bioavailability in comparison with the immediate release capsule dosage form. PMID:12754008

  11. Pressure Sensitive Paints

    NASA Technical Reports Server (NTRS)

    Liu, Tianshu; Bencic, T.; Sullivan, J. P.

    1999-01-01

    This article reviews new advances and applications of pressure sensitive paints in aerodynamic testing. Emphasis is placed on important technical aspects of pressure sensitive paint including instrumentation, data processing, and uncertainty analysis.

  12. Comparison of Surfactant Distributions in Pressure-Sensitive Adhesive Films Dried from Dispersion under Lab-Scale and Industrial Drying Conditions.

    PubMed

    Baesch, S; Siebel, D; Schmidt-Hansberg, B; Eichholz, C; Gerst, M; Scharfer, P; Schabel, W

    2016-03-01

    Film-forming latex dispersions are an important class of material systems for a variety of applications, for example, pressure-sensitive adhesives, which are used for the manufacturing of adhesive tapes and labels. The mechanisms occurring during drying have been under intense investigations in a number of literature works. Of special interest is the distribution of surfactants during the film formation. However, most of the studies are performed at experimental conditions very different from those usually encountered in industrial processes. This leaves the impact of the drying conditions and the resulting influence on the film properties unclear. In this work, two different 2-ethylhexyl-acrylate (EHA)-based adhesives with varying characteristics regarding glass transition temperature, surfactants, and particle size distribution were investigated on two different substrates. The drying conditions, defined by film temperature and mass transfer in the gas phase, were varied to emulate typical conditions encountered in the laboratory and industrial processes. Extreme conditions equivalent to air temperatures up to 250 °C in a belt dryer and drying rates of 12 g/(m(2)·s) were realized. The surfactant distributions were measured by means of 3D confocal Raman spectroscopy in the dry film. The surfactant distributions were found to differ significantly with drying conditions at moderate film temperatures. At elevated film temperatures the surfactant distributions are independent of the investigated gas side transport coefficients: the heat and mass transfer coefficient. Coating on substrates with significantly different surface energies has a large impact on surfactant concentration gradients, as the equilibrium between surface and bulk concentration changes. Dispersions with higher colloidal stability showed more homogeneous lateral surfactant distributions. These results indicate that the choice of the drying conditions, colloidal stability, and substrates is crucial

  13. Identification of carbonates as additives in pressure-sensitive adhesive tape substrate with Fourier transform infrared spectroscopy (FTIR) and its application in three explosive cases.

    PubMed

    Lv, Jungang; Feng, Jimin; Zhang, Wen; Shi, Rongguang; Liu, Yong; Wang, Zhaohong; Zhao, Meng

    2013-01-01

    Pressure-sensitive tape is often used to bind explosive devices. It can become important trace evidence in many cases. Three types of calcium carbonate (heavy, light, and active CaCO(3)), which were widely used as additives in pressure-sensitive tape substrate, were analyzed with Fourier transform infrared spectroscopy (FTIR) in this study. A Spectrum GX 2000 system with a diamond anvil cell and a deuterated triglycine sulfate detector was employed for IR observation. Background was subtracted for every measurement, and triplicate tests were performed. Differences in positions of main peaks and the corresponding functional groups were investigated. Heavy CaCO(3) could be identified from the two absorptions near 873 and 855/cm, while light CaCO(3) only has one peak near 873/cm because of the low content of aragonite. Active CaCO(3) could be identified from the absorptions in the 2800-2900/cm region because of the existence of organic compounds. Tiny but indicative changes in the 878-853/cm region were found in the spectra of CaCO(3) with different content of aragonite and calcite. CaCO(3) in pressure-sensitive tape, which cannot be differentiated by scanning electron microscope/energy dispersive X-ray spectrometer and thermal analysis, can be easily identified using FTIR. The findings were successfully applied to three specific explosive cases and would be helpful in finding the possible source of explosive devices in future cases. PMID:22724657

  14. Pressure-sensitive optrode

    DOEpatents

    Hirschfeld, T.B.

    1986-07-15

    An apparatus is provided for sensing changes in pressure and for generating optical signals related to said changes in pressure. Light from a fiber optic illuminates a fluorescent composition causing it to fluoresce. The fluorescent composition is caused to fluoresce more relative to the end of the fiber optic in response to changes in pressure so that the intensity of fluorescent emissions collected by the same fiber optic used for illumination varies monotonically with pressure. 10 figs.

  15. Pressure-sensitive optrode

    DOEpatents

    Hirschfeld, Tomas B.

    1986-01-01

    An apparatus is provided for sensing changes in pressure and for generating optical signals related to said changes in pressure. Light from a fiber optic illuminates a fluorescent composition causing it to fluoresce. The fluorescent composition is caused to more relative to the end of the fiber optic in response to changes in pressure so that the intensity of fluorescent emissions collected by the same fiber optic used for illumination varies monotonically with pressure.

  16. Pressure-sensitive optrode

    DOEpatents

    Hirschfeld, T.B.

    1985-04-09

    An apparatus and method are disclosed for sensing changes in pressure and for generating optical signals related to changes in pressure. Light from a fiber optic is directed to a movable surface which is coated with a light-responsive material, and which moves relative to the end of the fiber optic in response to changes in pressure. The same fiber optic collects a portion of the reflected or emitted light from the movable surface. Changes in pressure are determined by measuring changes in the amount of light collected. 5 figs.

  17. Pressure-sensitive optrode

    DOEpatents

    Hirschfeld, Tomas B.

    1985-01-01

    Apparatus and method for sensing changes in pressure and for generating optical signals related to changes in pressure. Light from a fiber optic is directed to a movable surface which is coated with a light-responsive material, and which moves relative to the end of the fiber optic in response to changes in pressure. The same fiber optic collects a portion of the reflected or emitted light from the movable surface. Changes in pressure are determined by measuring changes in the amount of light collected.

  18. Pressure-sensitive optrode

    DOEpatents

    Hirschfeld, T.B.

    1982-09-30

    Apparatus and method for sensing changes in pressure and for generating optical signals related to changes in pressure. Light from a fiber optic is directed to a movable surface which is coated with a light-responsive material, and which moves relative to the end of the fiber optic in response to changes in pressure. The same fiber optic collects a portion of the reflected or emitted light from the movable surface. Changes in pressure are determined by measuring changes in the amount of light collected.

  19. Effects of monomers on the properties of palm-oil-based radiation curable pressure sensitive adhesives (PSA) — a prepolymer method

    NASA Astrophysics Data System (ADS)

    Hilmi Mahmood, Mohd; Abdullah, Zahid; Sakurai, Yasuo; Zaman, Khairul; Mohd. Dahlan, Hj

    2001-01-01

    Various low glass transition temperature ( Tg) acrylate and methacrylate monomers were mixed with epoxidised palm oil acrylate (EPOLA) with the ratio of 50/50 prior to curing with electron beam (EB) irradiation. Methacrylate monomers such as dicyclopentenyloxyethyl methacrylate (DCPOEMA) and isobornyl methacrylate (ISBMA), although displaying relatively high adhesive properties were finally excluded from being further utilised as monomers for PSA because of a very slow curing speed. Literally, it is suggested that poorer adhesive performances of the cured films made from 50/50 : EPOLA/monomer mixture as compared to that of 100% monomer was attributed to the lack of compatibility between EPOLA and the particular monomers. Further compatibility investigations were continued using formulations prepared via the prepolymer route cured by ultraviolet (UV) irradiation and the results showed that several monoacrylate monomers with polar and non-polar groups exhibited high curing speed as well as good compatibility with EPOLA as shown by their cured film properties such as surface tackiness, peel adhesion and creep resistance. It is also suggested that these monomers were acting as surfactants for EPOLA which consequently enhance their compatibility upon mixing.

  20. Accuracy of Pressure Sensitive Paint

    NASA Technical Reports Server (NTRS)

    Liu, Tianshu; Guille, M.; Sullivan, J. P.

    2001-01-01

    Uncertainty in pressure sensitive paint (PSP) measurement is investigated from a standpoint of system modeling. A functional relation between the imaging system output and luminescent emission from PSP is obtained based on studies of radiative energy transports in PSP and photodetector response to luminescence. This relation provides insights into physical origins of various elemental error sources and allows estimate of the total PSP measurement uncertainty contributed by the elemental errors. The elemental errors and their sensitivity coefficients in the error propagation equation are evaluated. Useful formulas are given for the minimum pressure uncertainty that PSP can possibly achieve and the upper bounds of the elemental errors to meet required pressure accuracy. An instructive example of a Joukowsky airfoil in subsonic flows is given to illustrate uncertainty estimates in PSP measurements.

  1. Pressure sensitive conductive rubber blends

    SciTech Connect

    Hassan, H.H. ); Abdel-Bary, E.M. ); El-Mansy, M.K.; Khodair, H.A. )

    1989-12-01

    Butadiene-acrylonitrile rubber (NBR) was blended with polychloroprene (CR) according to standard techniques. The blend was mixed with different concentrations of ZnO. The vulcanized sample was subjected to electrical conductivity ({sigma}) measurements while different values of static pressure were applied on the sample. It was found that samples containing 7.5 phr ZnO showed a reasonable pressure sensitive increase of {sigma}. Furthermore, the {sigma} vs pressure relationship of rubber blend mixed with different concentrations of Fast Extrusion Furnace black (FEF) was investigated. It was found that rubber vulcanizate containing 40 phr FEF resulted in a negative value of the pressure coefficient of conductivity {approx equal} {minus} 4.5 KPa{sup {minus}1}.

  2. Graphene blisters with switchable shapes controlled by pressure and adhesion.

    PubMed

    Boddeti, Narasimha G; Liu, Xinghui; Long, Rong; Xiao, Jianliang; Bunch, J Scott; Dunn, Martin L

    2013-01-01

    We created graphene blisters that cover and seal an annular cylinder-shaped microcavity in a SiO2 substrate filled with a gas. By controlling the pressure difference between the gas inside and outside of the microcavity, we switch the graphene membrane between multiple stable equilibrium configurations. We carried out experiments starting from the situation where the pressure of the gas inside and outside of the microcavity is set equal to a prescribed charging pressure, p0 and the graphene membrane covers the cavity like an annular drum, adhered to the central post and the surrounding substrate due to van der Waals forces. We decrease the outside pressure to a value, pe which causes it to bulge into an annular blister. We systematically increase the charging pressure by repeating this procedure causing the annular blister to continue to bulge until a critical charging pressure pc(i) is reached. At this point the graphene membrane delaminates from the post in an unstable manner, resulting in a switch of graphene membrane shape from an annular to a spherical blister. Continued increase of the charging pressure results in the spherical blister growing with its height increasing, but maintaining a constant radius until a second critical charging pressure pc(o) is reached at which point the blister begins to delaminate from the periphery of the cavity in a stable manner. Here, we report a series of experiments as well as a mechanics and thermodynamic model that demonstrate how the interplay among system parameters (geometry, graphene stiffness (number of layers), pressure, and adhesion energy) results in the ability to controllably switch graphene blisters among different shapes. Arrays of these blisters can be envisioned to create pressure-switchable surface properties where the difference between patterns of annular versus spherical blisters will impact functionalities such as wettability, friction, adhesion, and surface wave characteristics. PMID:24224793

  3. Evaluation of yellow rectangle traps coated with hot melt pressure sensitive adhesive and sticky gel against Rhagoletis indifferens (Diptera:Tephritidae) and the possible influence of yellow colors on captures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sticky yellow rectangle traps have been used for many years to capture Rhagoletis fruit flies (Diptera: Tephritidae). Traditional yellow sticky traps are coated with a sticky gel (SG) that can leave residues on the hands of users. An alternative to SG on traps are hot melt pressure sensitive adhes...

  4. Diaphragm based high sensitive FBG pressure sensor

    NASA Astrophysics Data System (ADS)

    Vengal Rao, P.; Srimannarayana, K.; Sai Shankar, M.; Kishore, P.

    2013-06-01

    A high sensitive pressure sensor based on Fiber Bragg grating (FBG) integrated with a thin metal diaphragm was designed and demonstrated. To enhance the pressure sensitivity FBG is firmly glued across the diameter of the diaphragm. Under pressure, the diaphragm deforms and produces an induced strain along the length of the fiber causes shift in Bragg wavelength of the FBG. Pressure measurement is made by measuring the Bragg wavelength shift against change in pressure. The sensor was tested up to the maximum pressure of 140 psi and the corresponding pressure sensitivity was found to be 0.0204 nm/psi, which is approximately 970 times higher than that can be achieved with a bare FBG. The experimental results show good agreement with the theoretical results and possess good linearity and repeatability. This sensor can be used for the measurement of medium pressure, liquid level and depth of underwater.

  5. Stickiness--some fundamentals of adhesion.

    PubMed

    Gay, Cyprien

    2002-12-01

    We review some adhesion mechanisms that have been understood in the field of synthetic adhesives, and more precisely for adhesives that adhere instantaneously (a property named tackiness) and whose adhesive strength usually depends on the applied pressure (pressure-sensitive adhesives). The discussion includes effects of surface roughness, elasticity, cavitation, viscous and elastic fingering, substrate flexibility. PMID:21680396

  6. Optimization of measurements with pressure sensitive paints

    NASA Technical Reports Server (NTRS)

    Oglesby, Donald M.; Puram, Chith K.; Upchurch, Billy T.

    1995-01-01

    Use of luminescent paints for the measurement of global pressures on wind tunnel model surfaces requires a full understanding of the inherent accuracy of the technique. Theoretical emission of the paint luminophor follows the well known Stern-Volmer relation. Inherent in this relation are fundamental limits to achievable sensitivity and accuracy. Equations for relative error in pressure as a function of relative signal intensity (emittance), relative error in pressure as a function of pressure, and the relationship between sensitivity and pressure are derived and represented graphically.

  7. Pressure sensitivity of low permeability sandstones

    USGS Publications Warehouse

    Kilmer, N.H.; Morrow, N.R.; Pitman, J.K.

    1987-01-01

    Detailed core analysis has been carried out on 32 tight sandstones with permeabilities ranging over four orders of magnitude (0.0002 to 4.8 mD at 5000 psi confining pressure). Relationships between gas permeability and net confining pressure were measured for cycles of loading and unloading. For some samples, permeabilities were measured both along and across bedding planes. Large variations in stress sensitivity of permeability were observed from one sample to another. The ratio of permeability at a nominal confining pressure of 500 psi to that at 5000 psi was used to define a stress sensitivity ratio. For a given sample, confining pressure vs permeability followed a linear log-log relationship, the slope of which provided an index of pressure sensitivity. This index, as obtained for first unloading data, was used in testing relationships between stress sensitivity and other measured rock properties. Pressure sensitivity tended to increase with increase in carbonate content and depth, and with decrease in porosity, permeability and sodium feldspar. However, scatter in these relationships increased as permeability decreased. Tests for correlations between pressure sensitivity and various linear combinations of variables are reported. Details of pore structure related to diagenetic changes appears to be of much greater significance to pressure sensitivity than mineral composition. ?? 1987.

  8. A no adhesive and temperature-insensitive package design of fiber Bragg grating pressure sensor

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Zhu, Jun; Yin, Hao; Zhang, Zhao; Tang, Haiyu; Yu, Benli

    2012-11-01

    In this study, an innovative temperature-insensitive and no adhesive package for FBG pressure sensor was designed. We presents an package construction to compensate for temperature deviation of a FBG by mechanical properties of different metal materials; the package realize no adhesive utilizing combined technique of electroless plating NI-P and electroplating NI and laser spot welding technology. On the basis of the study on the Material structural properties and the compensation principles analysis of the FBG, the finite element method is used to analysis of the feasibility of the construction and optimize the construction parameters. The results show that this compensation construction can effectively reduce the temperature sensitivity of the FBG.

  9. Pressure-Sensitive Paint: Effect of Substrate

    PubMed Central

    Quinn, Mark Kenneth; Yang, Leichao; Kontis, Konstantinos

    2011-01-01

    There are numerous ways in which pressure-sensitive paint can be applied to a surface. The choice of substrate and application method can greatly affect the results obtained. The current study examines the different methods of applying pressure-sensitive paint to a surface. One polymer-based and two porous substrates (anodized aluminum and thin-layer chromatography plates) are investigated and compared for luminescent output, pressure sensitivity, temperature sensitivity and photodegradation. Two luminophores [tris-Bathophenanthroline Ruthenium(II) Perchlorate and Platinum-tetrakis (pentafluorophenyl) Porphyrin] will also be compared in all three of the substrates. The results show the applicability of the different substrates and luminophores to different testing environments. PMID:22247685

  10. Improved secondary caries resistance via augmented pressure displacement of antibacterial adhesive

    PubMed Central

    Zhou, Wei; Niu, Li-na; Huang, Li; Fang, Ming; Chang, Gang; Shen, Li-juan; Tay, Franklin R.; Chen, Ji-hua

    2016-01-01

    The present in vitro study evaluated the secondary caries resistance potential of acid-etched human coronal dentin bonded using augmented pressure adhesive displacement in conjunction with an experimental antibacterial adhesive. One hundred and twenty class I cavities were restored with a commercial non-antibacterial etch-and-rinse adhesive (N) or an experimental antibacterial adhesive (A) which was displaced by gentle air-blow (G) or augmented pressure air-blow (H). After bonding and restoration with resin composite, the resulted 4 groups (N-G, N-H, A-G and A-H) were exposed to Streptococcus mutans biofilm for 4, 8, 15, 20 or 25 days. The development of secondary caries in the bonding interface was then examined by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Data acquired from 15, 20 and 25 days of artificial caries induction were analyzed with three-way ANOVA at α = 0.05. The depth of the artificial carious lesions was significantly affected by “adhesive type” (Single Bond 2 vs experimental antibacterial adhesive p = 0.003), “intensity of adhesive displacement” (gentle vs augmented-pressure adhesive displacement; p < 0.001), as well as “artificial caries induction time” (p < 0.001). The combined use of augmented pressure adhesive displacement and experimental antibacterial adhesive reduces the progression of secondary caries. PMID:26928742

  11. Effect of fibril shape on adhesive properties

    NASA Astrophysics Data System (ADS)

    Soto, Daniel; Hill, Ginel; Parness, Aaron; Esparza, Noé; Cutkosky, Mark; Kenny, Tom

    2010-08-01

    Research into the gecko's adhesive system revealed a unique architecture for adhesives using tiny hairs. By using a stiff material (β-keratin) to create a highly structured adhesive, the gecko's system demonstrates properties not seen in traditional pressure-sensitive adhesives which use a soft, unstructured planar layer. In contrast to pressure sensitive adhesives, the gecko adhesive displays frictional adhesion, in which increased shear force allows it to withstand higher normal loads. Synthetic fibrillar adhesives have been fabricated but not all demonstrate this frictional adhesion property. Here we report the dual-axis force testing of single silicone rubber pillars from synthetic adhesive arrays. We find that the shape of the adhesive pillar dictates whether frictional adhesion or pressure-sensitive behavior is observed. This work suggests that both types of behavior can be achieved with structures much larger than gecko terminal structures. It also indicates that subtle differences in the shape of these pillars can significantly influence their properties.

  12. Application of atmospheric pressure plasma in polymer and composite adhesion

    NASA Astrophysics Data System (ADS)

    Yu, Hang

    An atmospheric pressure helium and oxygen plasma was used to investigate surface activation and bonding in polymer composites. This device was operated by passing 1.0-3.0 vol% of oxygen in helium through a pair of parallel plate metal electrodes powered by 13.56 or 27.12 MHz radio frequency power. The gases were partially ionized between the capacitors where plasma was generated. The reactive species in the plasma were carried downstream by the gas flow to treat the substrate surface. The temperature of the plasm gas reaching the surface of the substrate did not exceed 150 °C, which makes it suitable for polymer processing. The reactive species in the plasma downstream includes ~ 1016-1017 cm-3 atomic oxygen, ~ 1015 cm-3 ozone molecule, and ~ 10 16 cm-3 metastable oxygen molecule (O2 1Deltag). The substrates were treated at 2-5 mm distance from the exit of the plasma. Surface properties of the substrates were characterized using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). Subsequently, the plasma treated samples were bonded adhesively or fabricated into composites. The increase in mechanical strength was correlated to changes in the material composition and structure after plasma treatment. The work presented hereafter establishes atmospheric pressure plasma as an effective method to activate and to clean the surfaces of polymers and composites for bonding. This application can be further expanded to the activation of carbon fibers for better fiber-resin interactions during the fabrication of composites. Treating electronic grade FR-4 and polyimide with the He/O2 plasma for a few seconds changed the substrate surface from hydrophobic to hydrophilic, which allowed complete wetting of the surface by epoxy in underfill applications. Characterization of the surface by X-ray photoelectron spectroscopy shows formation of oxygenated functional groups, including hydroxyl, carbonyl, and

  13. Water-Based Pressure-Sensitive Paints

    NASA Technical Reports Server (NTRS)

    Jordan, Jeffrey D.; Watkins, A. Neal; Oglesby, Donald M.; Ingram, JoAnne L.

    2006-01-01

    Water-based pressure-sensitive paints (PSPs) have been invented as alternatives to conventional organic-solvent-based pressure-sensitive paints, which are used primarily for indicating distributions of air pressure on wind-tunnel models. Typically, PSPs are sprayed onto aerodynamic models after they have been mounted in wind tunnels. When conventional organic-solvent-based PSPs are used, this practice creates a problem of removing toxic fumes from inside the wind tunnels. The use of water-based PSPs eliminates this problem. The waterbased PSPs offer high performance as pressure indicators, plus all the advantages of common water-based paints (low toxicity, low concentrations of volatile organic compounds, and easy cleanup by use of water).

  14. Pressure and Temperature Sensitive Paint Field System

    NASA Technical Reports Server (NTRS)

    Sprinkle, Danny R.; Obara, Clifford J.; Amer, Tahani R.; Faulcon, Nettie D.; Carmine, Michael T.; Burkett, Cecil G.; Pritchard, Daniel W.; Oglesby, Donald M.

    2004-01-01

    This report documents the Pressure and Temperature Sensitive Paint Field System that is used to provide global surface pressure and temperature measurements on models tested in Langley wind tunnels. The system was developed and is maintained by Global Surface Measurements Team personnel of the Data Acquisition and Information Management Branch in the Research Facilities Services Competency. Descriptions of the system hardware and software are presented and operational procedures are detailed.

  15. Sterilization of Fuji pressure-sensitive film.

    PubMed

    Liggins, A B; Hardie, W R; Finlay, J B

    1994-11-01

    Fuji Prescale film is a pressure-sensitive medium which produces a characteristic pink stain on the application of pressure. Up to a saturation level, increases in pressure will produce a denser stain, thereby providing a method of determining pressures within the interface between two articulating surfaces. The relationship between the magnitude of applied pressure and the optical density of the resulting stain is non-linear; this relationship also varies with ambient temperature and humidity, in addition to load rate, and therefore requires a calibration procedure prior to use. The use of Fuji prescale film for recording interface pressures within the joint space in vivo has been widely reported; however, the object of this study was to assess the effects of sterilizing this medium, with a view to future in vivo applications. Samples of Fuji film were sterilized using a standard ethylene oxide (ETO) gas process and their subsequent pressure-recording properties were compared to a control group of samples. The 'optical-density vs pressure' relationship for the sterilized group was significantly different from that of the control group (paired Student's t-test, P < = 0.001); however, both groups provided reliable data across the same pressure-range and both exhibited an excellent degree of repeatability (coefficient of variation < 2.5%). It was concluded that Fuji film will continue to produce pressure-stains following ETO sterilization; however, the calibration of this film will only be valid if it is conducted using film from the sterilized group. PMID:7858782

  16. Adhesion

    MedlinePlus

    ... adhesions Ovarian cyst References Munireddy S, Kavalukas SL, Barbul A. Intra-abdominal healing: gastrointestinal tract and adhesions. Surg Clin N Am Kulaylat MN, Dayton, MT. Surgical complications. In: Townsend CM Jr, Beauchamp RD, Evers BM, Mattox KL, ...

  17. High blood pressure and visual sensitivity

    NASA Astrophysics Data System (ADS)

    Eisner, Alvin; Samples, John R.

    2003-09-01

    The study had two main purposes: (1) to determine whether the foveal visual sensitivities of people treated for high blood pressure (vascular hypertension) differ from the sensitivities of people who have not been diagnosed with high blood pressure and (2) to understand how visual adaptation is related to standard measures of systemic cardiovascular function. Two groups of middle-aged subjects-hypertensive and normotensive-were examined with a series of test/background stimulus combinations. All subjects met rigorous inclusion criteria for excellent ocular health. Although the visual sensitivities of the two subject groups overlapped extensively, the age-related rate of sensitivity loss was, for some measures, greater for the hypertensive subjects, possibly because of adaptation differences between the two groups. Overall, the degree of steady-state sensitivity loss resulting from an increase of background illuminance (for 580-nm backgrounds) was slightly less for the hypertensive subjects. Among normotensive subjects, the ability of a bright (3.8-log-td), long-wavelength (640-nm) adapting background to selectively suppress the flicker response of long-wavelength-sensitive (LWS) cones was related inversely to the ratio of mean arterial blood pressure to heart rate. The degree of selective suppression was also related to heart rate alone, and there was evidence that short-term changes of cardiovascular response were important. The results suggest that (1) vascular hypertension, or possibly its treatment, subtly affects visual function even in the absence of eye disease and (2) changes in blood flow affect retinal light-adaptation processes involved in the selective suppression of the flicker response from LWS cones caused by bright, long-wavelength backgrounds.

  18. Blade Tip Pressure Measurements Using Pressure Sensitive Paint

    NASA Technical Reports Server (NTRS)

    Wong, Oliver D.; Watkins, Anthony Neal; Goodman, Kyle Z.; Crafton, James; Forlines, Alan; Goss, Larry; Gregory, James W.; Juliano, Thomas J.

    2012-01-01

    This paper discusses the application of pressure sensitive paint using laser-based excitation for measurement of the upper surface pressure distribution on the tips of rotor blades in hover and simulated forward flight. The testing was conducted in the Rotor Test Cell and the 14- by 22-ft Subsonic Tunnel at the NASA Langley Research Center on the General Rotor Model System (GRMS) test stand. The Mach-scaled rotor contained three chordwise rows of dynamic pressure transducers for comparison with PSP measurements. The rotor had an 11 ft 1 in. diameter, 5.45 in. main chord and a swept, tapered tip. Three thrust conditions were examined in hover, C(sub T) = 0.004, 0.006 and 0.008. In forward flight, an additional thrust condition, C(sub T) = 0.010 was also examined. All four thrust conditions in forward flight were conducted at an advance ratio of 0.35.

  19. Prestress and Adhesion Site Dynamics Control Cell Sensitivity to Extracellular Stiffness

    PubMed Central

    Féréol, S.; Fodil, R.; Laurent, V.M.; Balland, M.; Louis, B.; Pelle, G.; Hénon, S.; Planus, E.; Isabey, D.

    2009-01-01

    This study aims at improving the understanding of mechanisms responsible for cell sensitivity to extracellular environment. We explain how substrate mechanical properties can modulate the force regulation of cell sensitive elements primarily adhesion sites. We present a theoretical and experimental comparison between two radically different approaches of the force regulation of adhesion sites that depends on their either stationary or dynamic behavior. The most classical stationary model fails to predict cell sensitivity to substrate stiffness whereas the dynamic model predicts extracellular stiffness dependence. This is due to a time dependent reaction force in response to actomyosin traction force exerted on cell sensitive elements. We purposely used two cellular models, i.e., alveolar epithelial cells and alveolar macrophages exhibiting respectively stationary and dynamic adhesion sites, and compared their sensitivity to theoretical predictions. Mechanical and structural results show that alveolar epithelial cells exhibit significant prestress supported by evident stress fibers and lacks sensitivity to substrate stiffness. On the other hand, alveolar macrophages exhibit low prestress and exhibit sensitivity to substrate stiffness. Altogether, theory and experiments consistently show that adhesion site dynamics and cytoskeleton prestress control cell sensitivity to extracellular environment with an optimal sensitivity expected in the intermediate range. PMID:19254561

  20. Pressure Sensitive Insulated Gate Field Effect Transistor

    NASA Astrophysics Data System (ADS)

    Suminto, James Tjan-Meng

    A pressure sensitive insulated gate field effect transistor has been developed. The device is an elevated gate field-effect-transistor. It consists of a p-type silicon substrate in which two n^+ region, the source and drain, are formed. The gate electrode is a metal film sandwiched in an insulated micro-diaphragm resembling a pill-box which covers the gate oxide, drain, and source. The space between the gate electrode and the oxide is vacuum or an air-gap. When pressure is applied on the diaphragm it deflects and causes a change in the gate capacitance, and thus modulates the conductance of the channel between source and drain. A general theory dealing with the characteristic of this pressure sensitive insulated gate field effect transistor has been derived, and the device fabricated. The fabrication process utilizes the standard integrated circuit fabrication method. It features a batch fabrication of field effect devices followed by the batch fabrication of the deposited diaphragm on top of each field effect device. The keys steps of the diaphragm fabrication are the formation of spacer layer, formation of the diaphragm layer, and the subsequent removal of the spacer layer. The chip size of the device is 600 μm x 1050 mum. The diaphragm size is 200 μm x 200 mum. Characterization of the device has been performed. The current-voltage characteristics with pressure as parameters have been demonstrated and the current-pressure transfer curves obtained. They show non-linear characteristics as those of conventional capacitive pressure sensors. The linearity of threshold voltage versus pressure transfer curves has been demonstrated. The temperature effect on the device performances has been tested. The temperature coefficient of threshold voltage, rather than the electron mobility, has dominated the temperature coefficient of the device. Two temperature compensation schemes have been tested: one method is by connecting two identical PSIGFET in a differential amplifier

  1. Water-Based Pressure Sensitive Paint

    NASA Technical Reports Server (NTRS)

    Oglesby, Donald M.; Ingram, JoAnne L.; Jordan, Jeffrey D.; Watkins, A. Neal; Leighty, Bradley D.

    2004-01-01

    Preparation and performance of a water-based pressure sensitive paint (PSP) is described. A water emulsion of an oxygen permeable polymer and a platinum porphyrin type luminescent compound were dispersed in a water matrix to produce a PSP that performs well without the use of volatile, toxic solvents. The primary advantages of this PSP are reduced contamination of wind tunnels in which it is used, lower health risk to its users, and easier cleanup and disposal. This also represents a cost reduction by eliminating the need for elaborate ventilation and user protection during application. The water-based PSP described has all the characteristics associated with water-based paints (low toxicity, very low volatile organic chemicals, and easy water cleanup) but also has high performance as a global pressure sensor for PSP measurements in wind tunnels. The use of a water-based PSP virtually eliminates the toxic fumes associated with the application of PSPs to a model in wind tunnels.

  2. Frequency Response of Pressure Sensitive Paints

    NASA Technical Reports Server (NTRS)

    Winslow, Neal A.; Carroll, Bruce F.; Setzer, Fred M.

    1996-01-01

    An experimental method for measuring the frequency response of Pressure Sensitive Paints (PSP) is presented. These results lead to the development of a dynamic correction technique for PSP measurements which is of great importance to the advancement of PSP as a measurement technique. The ability to design such a dynamic corrector is most easily formed from the frequency response of the given system. An example of this correction technique is shown. In addition to the experimental data, an analytical model for the frequency response is developed from the one dimensional mass diffusion equation.

  3. Effect of different adhesive strategies on the post-operative sensitivity of class I composite restorations

    PubMed Central

    Sancakli, Hande Sar; Yildiz, Esra; Bayrak, Isil; Ozel, Sevda

    2014-01-01

    Objective: To evaluate the post-operative sensitivity of occlusal restorations using different dentin adhesives performed by an undergraduate and a post-doctorate dentist. Materials and Methods: One hundred and eighty-eight molar occlusal restorations were placed in 39 patients (ages between 18 and 30) using 3 different kind of adhesive systems; Optibond FL (OBF), Clearfil Protect Bond (CPB), and iBond (IB) by a post-doctorate dentist or a fifth-year dental student according to the manufacturers’ instructions. Post-operative sensitivity to cold and air was evaluated using a Visual Analog Scale (VAS) after 24 hours, 30, 90, and 180 days. Data were analyzed using the Mann-Whitney U and Friedman tests (P < 0.05). Results: Post-operative sensitivity scores for OBF and CPB were higher for the dental student (P < 0.05), while IB scores did not differ statistical significantly according to the operator (P > 0.05). Conclusion: Operator skill and experience appears to play a role in determining the outcome of post-operative sensitivity of multi-step adhesive systems although the post-operative sensitivity was low. It is suggested that the less experienced clinicians (rather than experienced clinicians) should better use the self-etching dentin bonding systems with reduced application steps to minimize the potential risk of post-operative sensitivity of dental adhesives. PMID:24966741

  4. Effects of a Temperature-Sensitive, Anti-Adhesive Agent on the Reduction of Adhesion in a Rabbit Laminectomy Model

    PubMed Central

    Park, Jeong Woo; Cho, Tae Koo; Chun, Hyoung-Joon; Ryu, Je Il

    2016-01-01

    Objective A common cause of failure in laminectomy surgery is when epidural, peridural, or perineural adhesion occurs postoperatively. The purpose of this study is to examine the efficacy of a temperature-sensitive, anti-adhesive agent (TSAA agent), Guardix-SG®, as a mechanical barrier for the prevention or reduction of peridural scar adhesion in a rabbit laminectomy model. Methods Twenty-six mature rabbits were used for this study. Each rabbit underwent two separate laminectomies at lumbar vertebrae L3 and L6, left empty (the control group) and applied 2 mL of the TSAA agent (the experimental group), respectively. Invasive scar formation or inflammation after laminectomy was quantitatively evaluated by measuring the thickness of the dura, the distance from the surface of dura to the scar tissues, the number of inflammatory cells in the scar tissues at the laminectomy site, and the concentration of collagen in histological sections. Results At 6 weeks postsurgery, the dura was significantly thinner and the distance from the surface of dura to the scar tissues was greater in the experimental group than in the control group (p=0.04 and p=0.01). The number of inflammatory cells was not significantly different in the two groups (p=0.08), although the mean number of inflammatory cells was relatively lower in the experimental group than in the control group. Conclusion The current study suggests that the TSAA agent, Guardix-SG®, could be useful as an interpositional physical barrier after laminectomy for the prevention or reduction of adhesion. PMID:27226857

  5. Investigation Of Adhesion Formation In New Stainless Steel Trim Spring Operated Pressure Relief Valves

    SciTech Connect

    Gross, Robert E.; Bukowski, Julia V.; Goble, William M.

    2013-04-16

    Examination of proof test data for new (not previously installed) stainless steel (SS) trim spring operated pressure relief valves (SOPRV) reveals that adhesions form between the seat and disc in about 46% of all such SOPRV. The forces needed to overcome these adhesions can be sufficiently large to cause the SOPRV to fail its proof test (FPT) prior to installation. Furthermore, a significant percentage of SOPRV which are found to FPT are also found to ''fail to open'' (FTO) meaning they would not relief excess pressure in the event of an overpressure event. The cases where adhesions result in FTO or FPT appear to be confined to SOPRV with diameters < 1 in and set pressures < 150 psig and the FTO are estimated to occur in 0.31% to 2.00% of this subpopulation of SS trim SOPRV. The reliability and safety implications of these finding for end-users who do not perform pre-installation testing of SOPRV are discussed.

  6. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... the identity prescribed in § 177.1620(a) of this chapter. (6) 4- amino]-2,6-di-tert-butylphenol (CAS...) Butanedioic acid, sulfo-1,4-di-(C9-C11 alkyl) ester, ammonium salt (also known as butanedioic acid sulfo-1,...

  7. [Allergens-induced sensitization alters airway epithelial adhesion molecules expression in mice].

    PubMed

    Zeng, Dan; Tan, Mei-Ling; Xiang, Yang; Qin, Xiao-Qun; Zhu, Li-Ming; Dai, Ai-Guo

    2015-12-25

    To explore the relationship between the epithelial adhesion molecules and immune responses of airway epithelium, we observed the expression of integrin β4 and intercellular adhesion molecule-1 (ICAM-1) in the mice airway epithelium after sensitization with allergens. BALB/c mice were sensitized with intraperitoneal injection of ovalbumin (OVA) or house dust mite (HDM) and then developed airway hyper-responsiveness as determined by barometric whole-body plethysmography. Both OVA and HDM sensitization led to increases of the number of peripheral leukocytes as well as inflammatory cells infiltration in lungs. OVA sensitized mice showed more severe inflammatory cells infiltration than HDM sensitized mice. Immunohistochemistry analysis of mice lung tissues revealed that sensitization with both allergens also led to a decrease of integrin β4 expression and an increase of ICAM-1 expression in airway epithelia. OVA sensitized mice showed a more significant increase of ICAM-1 expression compared with HDM sensitized mice. siRNA mediated silencing of integrin β4 gene in 16HBE cells resulted in an up-regulation of ICAM-1 expression. Our results indicate a possible role of airway epithelial adhesion molecules in allergen-induced airway immune responses. PMID:26701635

  8. Durability of solvent-free one-step self-etch adhesive under simulated intrapulpal pressure

    PubMed Central

    2015-01-01

    Background There are different solvents presented in simplified adhesives. Bond-1 SF has been developed, which contains neither water nor organic solvents, in order to eliminate technical issues in terms of evaporation of solvents and concerns for the durability of resin-dentin bond. Thus this study was conducted to evaluate the microtensile bond strength (?TBS) of solvent-free and ethanol-based one-step self-etch adhesives to dentin under simulated intrapulpal pressure (IPP). Material and Methods Occlusal surfaces of human molars were prepared to expose mid-dentin depth. Bond-1SF Solvent-Free SE [SF] and AdperTM easy one adhesives [AE] were applied on dentin specimens. Resin composite build up was done in increments. Then specimens were stored under simulated IPP 20 mmHg, immersed in artificial saliva at 37 ºC for 24 hours (24h) and 6 months (6m). Specimens were sectioned into sticks of (1 mm²) to be tested for (?TBS) using a universal testing machine. Both fractured sections of each stick were inspected using a stereomicroscope at 40× magnification to determine the mode of failure. Data were statistically analyzed by Two-way ANOVA of Variance. Results There was no statistically significant difference between the mean ?TBS of both [SF] and [AE] adhesives at both aging periods, 24h and 6m (p< 0.1103) and (p< 0.7148) respectively. Only for [AE] there was statistical significance for aging periods (p< 0.0057*). The most represented modes of failure were adhesive failure at tooth side. Conclusions Under simulated IPP solvent-free adhesive [SF] had comparable performance as ethanol-based adhesive [AE] when bonded to dentin substrate. Key words:Bond strength, dentin, simulated intrapulpal pressure, self-etch adhesives, solvents. PMID:26535091

  9. Imaging leukocyte adhesion to the vascular endothelium at high intraluminal pressure.

    PubMed

    Michell, Danielle L; Andrews, Karen L; Woollard, Kevin J; Chin-Dusting, Jaye P F

    2011-01-01

    Worldwide, hypertension is reported to be in approximately a quarter of the population and is the leading biomedical risk factor for mortality worldwide. In the vasculature hypertension is associated with endothelial dysfunction and increased inflammation leading to atherosclerosis and various disease states such as chronic kidney disease(2), stroke(3) and heart failure(4). An initial step in vascular inflammation leading to atherogenesis is the adhesion cascade which involves the rolling, tethering, adherence and subsequent transmigration of leukocytes through the endothelium. Recruitment and accumulation of leukocytes to the endothelium is mediated by an upregulation of adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1), intracellular cell adhesion molecule-1 (ICAM-1) and E-selectin as well as increases in cytokine and chemokine release and an upregulation of reactive oxygen species(5). In vitro methods such as static adhesion assays help to determine mechanisms involved in cell-to-cell adhesion as well as the analysis of cell adhesion molecules. Methods employed in previous in vitro studies have demonstrated that acute increases in pressure on the endothelium can lead to monocyte adhesion, an upregulation of adhesion molecules and inflammatory markers(6) however, similar to many in vitro assays, these findings have not been performed in real time under physiological flow conditions, nor with whole blood. Therefore, in vivo assays are increasingly utilised in animal models to demonstrate vascular inflammation and plaque development. Intravital microscopy is now widely used to assess leukocyte adhesion, rolling, migration and transmigration(7-9). When combining the effects of pressure on leukocyte to endothelial adhesion the in vivo studies are less extensive. One such study examines the real time effects of flow and shear on arterial growth and remodelling but inflammatory markers were only assessed via immunohistochemistry(10). Here we present

  10. Monitoring the Contact Stress Distribution of Gecko-Inspired Adhesives Using Mechano-Sensitive Surface Coatings.

    PubMed

    Neubauer, Jens W; Xue, Longjian; Erath, Johann; Drotlef, Dirk-M; Campo, Aránzazu Del; Fery, Andreas

    2016-07-20

    The contact geometry of microstructured adhesive surfaces is of high relevance for adhesion enhancement. Theoretical considerations indicate that the stress distribution in the contact zone is crucial for the detachment mechanism, but direct experimental evidence is missing so far. In this work, we propose a method that allows, for the first time, the detection of local stresses at the contact area of biomimetic adhesive microstructures during contact formation, compression and detachment. We use a mechano-sensitive polymeric layer, which turns mechanical stresses into changes of fluorescence intensity. The biomimetic surface is brought into contact with this layer in a well-defined fashion using a microcontact printer, while the contact area is monitored with fluorescence microscopy in situ. Thus, changes in stress distribution across the contact area during compression and pull-off can be visualized with a lateral resolution of 1 μm. We apply this method to study the enhanced adhesive performance of T-shaped micropillars, compared to flat punch microstructures. We find significant differences in the stress distribution of the both differing contact geometries during pull-off. In particular, we find direct evidence for the suppression of crack nucleation at the edge of T-shaped pillars, which confirms theoretical models for the superior adhesive properties of these structures. PMID:27327111

  11. Effect of Atmospheric Pressure Plasma Modification on Polyimide and Adhesive Joining with Titanium

    NASA Astrophysics Data System (ADS)

    Akram, M.; Jansen, K. M. B.; Ernst, L. J.; Bhowmik, S.; Ajeesh, G.; Ahmed, S.; Chakraborty, D.

    2015-10-01

    This investigation highlights the effect of surface modification on polyimide by atmospheric pressure plasma treatment with different exposure time. Surface modification of polymer by plasma treatment essentially creates physical and chemical changes such as cross-linking and formation of free radicals. It also forms oxygen functionalization in the form of polar groups on polymer surface, hence improving the wetting and adhesion properties. It is observed that surface energy of the polymer increases with increasing exposure time of atmospheric pressure plasma. However, prolonged exposure time of plasma results in deterioration of the surface layer of polyimide resulting in degradation and embrittlement. Scanning electron microscopy and atomic force microscopy analysis reveal that there is a considerable morphological change on the polymer surface due to atmospheric pressure plasma treatment. X-ray photo electron spectroscopy analysis reveals that the oxygen functionalities of polymer surface increases significantly when polyimide is exposed to atmospheric pressure plasma. Untreated and atmospheric pressure plasma-treated polyimide sheet are adhesive bonded by employing polyimide adhesive as well as with titanium substrate. Due to surface modification of polyimide, it is observed that there is a significant increase in lap shear tensile strength, and therefore, this technology is highly acceptable for aviation and space applications.

  12. High extracellular pressure promotes gastric cancer cell adhesion, invasion, migration and suppresses gastric cancer cell differentiation.

    PubMed

    Su, Changlei; Zhang, Bomiao; Liu, Wenzhi; Zheng, Hongqun; Sun, Lingyu; Tong, Jinxue; Wang, Tian; Jiang, Xiaofeng; Liang, Hongyan; Xue, Li; Zhang, Qifan

    2016-08-01

    Slightly increased pressure stimulates tumor cell adhesion and proliferation. In the present study, we aimed to evaluate the effects of high pressure on gene expression and the biological behavior of gastric cancer cells. After incubation for 30 min at 37˚C under ambient and increased pressure, one portion of SGC7901 cells was used for cell proliferation and apoptosis assays, cell cycle analysis, adhesion invasion or migration assays. The other portion of cells was harvested for detection of matrix metalloproteinase-2 (MMP-2), inhibitor of DNA binding-1 (ID1), sonic Hedgehog (SHH) and E-cadherin expression by western blotting or RT-PCR. In addition, we investigated the effects of high pressure on SGC7901 cell ultrastructure by transmission electron microscopy. We found that the adhesion fold under increased pressure of 760 and 1,520 mmHg was 2.39±1.05 (P<0.05) and 2.47±0.85 (P<0.01) as compared with the control, respectively. The invasion fold was 3.42±2.06 (P<0.05) and 5.13±2.49 (P<0.01) as compared with the control, respectively. The migration was 1.65±0.20 (P<0.001) and 2.53±0.50 (P<0.001) as compared with the control, respectively. At increased pressure, MMP-2 and ID1 expression increased significantly, while the expression of SHH decreased significantly. However, we did not find significant change in proliferation, apoptosis, cell cycle or ultrastructure of the SGC7901 cells under high pressure. In conclusion, high pressure promoted the adhesion, invasion and migration of SGC7901 cells. Moreover, the present study suggests that the pressure-augmented invasion and migration may be related to the increase in MMP-2 expression. Moreover, high pressure may suppress SGC7901 cell differentiation, which may result from the change in SHH and ID1 expression. PMID:27278077

  13. Rotor Blade Pressure Measurement in a Rotating Machinery Using Pressure and Temperature Sensitive Paints

    NASA Technical Reports Server (NTRS)

    Torgerson, S.; Liu, T.; Sullivan, J.

    1998-01-01

    Pressure and temperature sensitive paints have been utilized for the measurement of blade surface pressure and temperature distributions in a high speed axial compressor and an Allied Signal F109 gas turbine engine. Alternate blades were painted with temperature sensitive paints and then pressure sensitive paint. This combination allows temperature distributions to be accounted for when determining the blade suction surface pressure distribution. Measurements were taken and pressure maps on the suction surface of a blade were obtained over a range of rotational speeds. Pressure maps of the suction surface show-strong shock waves at the higher speeds.

  14. Sodium-sensitivity of Blood Pressure in Chinese Populations

    PubMed Central

    Chen, Jing

    2010-01-01

    Clinical trials have demonstrated that a reduced intake of dietary sodium lowers blood pressure. However, blood pressure reduction in response to a decrease in dietary sodium intake varies considerably among different individuals–a phenomenon described as sodium-sensitivity. The Genetic Epidemiology Network of Salt Sensitivity (GenSalt) study was a large family-based dietary-feeding study conducted in rural north China. This study indicated that approximately 39% of Chinese adults were sodium-sensitive. Sodium-sensitivity was more common in women and in persons who were older and had higher usual blood pressure. Sodium-sensitivity was also more common in individuals with higher responses to cold pressor test and in individuals with the metabolic syndrome. Genetic factors might play an important role in determining sodium-sensitivity in the Chinese population. A better understanding of the genetic and environmental determinants of sodium-sensitivity has important public health and clinical implications. PMID:20424958

  15. Fabrication of High Sensitivity Carbon Microcoil Pressure Sensors

    PubMed Central

    Su, Chih-Chung; Li, Chen-Hung; Chang, Neng-Kai; Gao, Feng; Chang, Shuo-Hung

    2012-01-01

    This work demonstrates a highly sensitive pressure sensor that was fabricated using carbon microcoils (CMCs) and polydimethylsiloxane (PDMS). CMCs were grown by chemical vapor deposition using various ratios of Fe-Sn catalytic solution. The pressure sensor has a sandwiched structure, in which the as-grown CMCs were inserted between two PDMS layers. The pressure sensor exhibits piezo-resistivity changes in response to mechanical loading using a load cell system. The yields of the growth of CMCs at a catalyst proportion of Fe:Sn = 95:5 reach 95%. Experimental results show that the sensor achieves a high sensitivity of 0.93%/kPa from the CMC yield of 95%. The sensitivity of the pressure sensor increases with increasing yield of CMCs. The demonstrated pressure sensor shows the advantage of high sensitivity and is suitable for mass production. PMID:23112586

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

    PubMed

    Purtov, Julia; Frensemeier, Mareike; Kroner, Elmar

    2015-11-01

    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 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. PMID:26457864

  17. 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

  18. Gigaseal Mechanics: Creep of the Gigaseal under the Action of Pressure, Adhesion, and Voltage

    PubMed Central

    2015-01-01

    Patch clamping depends on a tight seal between the cell membrane and the glass of the pipet. Why does the seal have such high electric resistance? Why does the patch adhere so strongly to the glass? Even under the action of strong hydrostatic, adhesion, and electrical forces, it creeps at a very low velocity. To explore possible explanations, we examined two physical models for the structure of the seal zone and the adhesion forces and two respective mechanisms of patch creep and electric conductivity. There is saline between the membrane and glass in the seal, and the flow of this solution under hydrostatic pressure or electroosmosis should drag a patch. There is a second possibility: the lipid core of the membrane is liquid and should be able to flow, with the inner monolayer slipping over the outer one. Both mechanisms predict the creep velocity as a function of the properties of the seal and the membrane, the pipet geometry, and the driving force. These model predictions are compared with experimental data for azolectin liposomes with added cholesterol or proteins. It turns out that to obtain experimentally observed creep velocities, a simple viscous flow in the seal zone requires ∼10 Pa·s viscosity; it is unclear what structure might provide that because that viscosity alone severely constrains the electric resistance of the gigaseal. Possibly, it is the fluid bilayer that allows the motion. The two models provide an estimate of the adhesion energy of the membrane to the glass and membrane’s electric characteristics through the comparison between the velocities of pressure-, adhesion-, and voltage-driven creep. PMID:25295693

  19. Gigaseal mechanics: creep of the gigaseal under the action of pressure, adhesion, and voltage.

    PubMed

    Slavchov, Radomir I; Nomura, Takeshi; Martinac, Boris; Sokabe, Masahiro; Sachs, Frederick

    2014-11-01

    Patch clamping depends on a tight seal between the cell membrane and the glass of the pipet. Why does the seal have such high electric resistance? Why does the patch adhere so strongly to the glass? Even under the action of strong hydrostatic, adhesion, and electrical forces, it creeps at a very low velocity. To explore possible explanations, we examined two physical models for the structure of the seal zone and the adhesion forces and two respective mechanisms of patch creep and electric conductivity. There is saline between the membrane and glass in the seal, and the flow of this solution under hydrostatic pressure or electroosmosis should drag a patch. There is a second possibility: the lipid core of the membrane is liquid and should be able to flow, with the inner monolayer slipping over the outer one. Both mechanisms predict the creep velocity as a function of the properties of the seal and the membrane, the pipet geometry, and the driving force. These model predictions are compared with experimental data for azolectin liposomes with added cholesterol or proteins. It turns out that to obtain experimentally observed creep velocities, a simple viscous flow in the seal zone requires ~10 Pa·s viscosity; it is unclear what structure might provide that because that viscosity alone severely constrains the electric resistance of the gigaseal. Possibly, it is the fluid bilayer that allows the motion. The two models provide an estimate of the adhesion energy of the membrane to the glass and membrane's electric characteristics through the comparison between the velocities of pressure-, adhesion-, and voltage-driven creep. PMID:25295693

  20. FAITH Pressure-Sensitive Paint and Surface Oil Flow Visualizations

    NASA Video Gallery

    Pressure-sensitive paint and surface oil flow visualization experiments are performed on a three dimensional model of a small hill. This experiment was part of a series of measurements of the compl...

  1. Increased adhesion of polydimethylsiloxane (PDMS) to acrylic adhesive tape for medical use by surface treatment with an atmospheric pressure rotating plasma jet

    NASA Astrophysics Data System (ADS)

    Jofre-Reche, José Antonio; Pulpytel, Jérôme; Arefi-Khonsari, Farzaneh; Martín-Martínez, José Miguel

    2016-08-01

    The surface properties of polydimethylsiloxane (PDMS) were modified by treatment with an atmospheric pressure rotating plasma jet (APPJ) and the surface modifications were studied to assess its hydrophilicity and adhesion to acrylic adhesive tape intended for medical applications. Furthermore, the extent of hydrophobic recovery under different storage conditions was studied. The surface treatment of PDMS with the APPJ under optimal conditions noticeably increased the oxygen content and most of the surface silicon species were fully oxidized. A brittle silica-like layer on the outermost surface was created showing changes in topography due to the formation of grooves and cracks. A huge improvement in T-peel and the shear adhesive strength of the APPJ-treated PDMS surface/acrylic tape joints was obtained. On the other hand, the hydrophilicity of the PDMS surface increased noticeably after the APPJ treatment, but 24 h after treatment almost 80% hydrophobicity was recovered and the adhesive strength was markedly reduced with time after the APPJ treatment. However, the application of an acrylic adhesive layer on the just-APPJ-treated PDMS surface retained the adhesive strength, limiting the extent of hydrophobic recovery.

  2. Pressure Sensitivity of Streptococcal Growth in Relation to Catabolism

    PubMed Central

    Marquis, Robert E.; Brown, William P.; Fenn, Wallace O.

    1971-01-01

    The sensitivity of Streptococcus faecalis growth to hydrostatic pressures ranging up to 550 atm was found to depend on the source of adenosine triphosphate for growth. Barotolerance of cultures growing in a complex medium with ribose as major catabolite appeared to be determined primarily by the pressure sensitivity of ribose-degrading enzymes. Apparent activation volumes for growth were nearly identical to those for lactate production from ribose, and yield coefficients per mole of ribose degraded were relatively independent of pressure. In contrast, cultures with glucose as main catabolite were less sensitive to pressure; glycolysis was less severely restricted under high pressure than was growth, and yield coefficients declined with pressure, especially above 400 atm. Thus, two distinct types of barotolerance could be defined—one dominated by catabolic reactions and one dominated by noncatabolic reactions. The results of experiments with a series of other catabolites further supported the view that catabolic reactions can determine streptococcal barotolerance. We also found that growing, glucose-degrading cultures increased in volume under pressure in the same manner that they do at 1 atm. Thus, it appeared that the bacterium has no alternative means of carrying out glycolysis under pressure without dilatation. Also, the observation that cultures grown under pressure did not contain abnormally large or morphologically deformed cells suggested that pressure did not inhibit cell division more than cell growth. PMID:4925191

  3. Diaphragm size and sensitivity for fiber optic pressure sensors

    NASA Technical Reports Server (NTRS)

    He, Gang; Cuomo, Frank W.; Zuckerwar, Allan J.

    1991-01-01

    A mechanism which leads to a significant increase in sensitivity and linear operating range in reflective type fiber optic pressure transducers with minute active dimensions is studied. A general theoretical formalism is presented which is in good agreement with the experimental data. These results are found useful in the development of small pressure sensors used in turbulent boundary layer studies and other applications.

  4. Determination of impact sensitivity of materials at high pressures

    NASA Technical Reports Server (NTRS)

    Davis, L.; Pippen, D.; Stradling, J.; Whitaker, D.

    1972-01-01

    Compact device is used to determine impact sensitivity of material in static, high pressure, gaseous environment. It can also be instrumented to monitor and record pressure, temperature, and striker impact force. Device is used in conjunction with commercially available liquid oxygen impact tester which provides impact energy.

  5. Application of Pressure Sensitive Paint in Hypersonic Flows

    NASA Technical Reports Server (NTRS)

    Jules, Kenol; Carbonaro, Mario; Zemsch, Stephan

    1995-01-01

    It is well known in the aerodynamic field that pressure distribution measurement over the surface of an aircraft model is a problem in experimental aerodynamics. For one thing, a continuous pressure map can not be obtained with the current experimental methods since they are discrete. Therefore, interpolation or CFD methods must be used for a more complete picture of the phenomenon under study. For this study, a new technique was investigated which would provide a continuous pressure distribution over the surface under consideration. The new method is pressure sensitive paint. When pressure sensitive paint is applied to an aerodynamic surface and placed in an operating wind-tunnel under appropriate lighting, the molecules luminesce as a function of the local pressure of oxygen over the surface of interest during aerodynamic flow. The resulting image will be brightest in the areas of low pressure (low oxygen concentration), and less intense in the areas of high pressure (where oxygen is most abundant on the surface). The objective of this investigation was to use pressure sensitive paint samples from McDonnell Douglas (MDD) for calibration purpose in order to assess the response of the paint under appropriate lighting and to use the samples over a flat plate/conical fin mounted at 75 degrees from the center of the plate in order to study the shock/boundary layer interaction at Mach 6 in the Von Karman wind-tunnel. From the result obtained it was concluded that temperature significantly affects the response of the paint and should be given the uppermost attention in the case of hypersonic flows. Also, it was found that past a certain temperature threshold, the paint intensity degradation became irreversible. The comparison between the pressure tap measurement and the pressure sensitive paint showed the right trend. However, there exists a shift when it comes to the actual value. Therefore, further investigation is under way to find the cause of the shift.

  6. Pressure sensitive multifunctional solar cells using carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Somani, Prakash R.

    2010-04-01

    A unique multifunctional device combining the photovoltaic action and pressure sensitivity is demonstrated which is based on the heterojunction of n-Si and carbon nanotubes (double walled carbon nanotubes or multiwalled carbon nanotubes) and using copper phthalocyanine surface modified indium-tin-oxide electrode and shows pressure dependent photovoltaic action. The device can work as a solar cell, pressure sensor, or photovoltaic pressure sensor. Such multifunctional organic/organic-inorganic hybrid solar cells are expected to find many applications in the near future.

  7. A highly sensitive and flexible pressure sensor with electrodes and elastomeric interlayer containing silver nanowires.

    PubMed

    Wang, Jun; Jiu, Jinting; Nogi, Masaya; Sugahara, Tohru; Nagao, Shijo; Koga, Hirotaka; He, Peng; Suganuma, Katsuaki

    2015-02-21

    The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present study a simple printing process without complex patterning has been used for constructing the sensor, and an interlayer is employed comprising elastomeric composites filled with silver nanowires. By increasing the relative permittivity, εr, of the composite interlayer induced by compression at high nanowire concentration, it has been possible to achieve a maximum sensitivity of 5.54 kPa(-1). The improvement in sensitivity did not sacrifice or undermine the other features of the sensor. Thanks to the silver nanowire electrodes, the sensor is flexible and stable after 200 cycles at a bending radius of 2 mm, and exhibits outstanding reproducibility without hysteresis under similar pressure pulses. The sensor has been readily integrated onto an adhesive bandage and has been successful in detecting human movements. In addition to measuring pressure in direct contact, non-contact pressures such as air flow can also be detected. PMID:25588044

  8. Pressure Sensitive Paint Applied to Flexible Models Project

    NASA Technical Reports Server (NTRS)

    Schairer, Edward T.; Kushner, Laura Kathryn

    2014-01-01

    One gap in current pressure-measurement technology is a high-spatial-resolution method for accurately measuring pressures on spatially and temporally varying wind-tunnel models such as Inflatable Aerodynamic Decelerators (IADs), parachutes, and sails. Conventional pressure taps only provide sparse measurements at discrete points and are difficult to integrate with the model structure without altering structural properties. Pressure Sensitive Paint (PSP) provides pressure measurements with high spatial resolution, but its use has been limited to rigid or semi-rigid models. Extending the use of PSP from rigid surfaces to flexible surfaces would allow direct, high-spatial-resolution measurements of the unsteady surface pressure distribution. Once developed, this new capability will be combined with existing stereo photogrammetry methods to simultaneously measure the shape of a dynamically deforming model in a wind tunnel. Presented here are the results and methodology for using PSP on flexible surfaces.

  9. Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers

    NASA Astrophysics Data System (ADS)

    Mannsfeld, Stefan C. B.; Tee, Benjamin C.-K.; Stoltenberg, Randall M.; Chen, Christopher V. H.-H.; Barman, Soumendra; Muir, Beinn V. O.; Sokolov, Anatoliy N.; Reese, Colin; Bao, Zhenan

    2010-10-01

    The development of an electronic skin is critical to the realization of artificial intelligence that comes into direct contact with humans, and to biomedical applications such as prosthetic skin. To mimic the tactile sensing properties of natural skin, large arrays of pixel pressure sensors on a flexible and stretchable substrate are required. We demonstrate flexible, capacitive pressure sensors with unprecedented sensitivity and very short response times that can be inexpensively fabricated over large areas by microstructuring of thin films of the biocompatible elastomer polydimethylsiloxane. The pressure sensitivity of the microstructured films far surpassed that exhibited by unstructured elastomeric films of similar thickness, and is tunable by using different microstructures. The microstructured films were integrated into organic field-effect transistors as the dielectric layer, forming a new type of active sensor device with similarly excellent sensitivity and response times.

  10. Image measurements of unsteady pressure fluctuation by a pressure-sensitive coating on porous anodized aluminium

    NASA Astrophysics Data System (ADS)

    Kameda, M.; Tabei, T.; Nakakita, K.; Sakaue, H.; Asai, K.

    2005-12-01

    Pressure-sensitive luminescent coating on porous anodized aluminium (AA-PSP) was applied to measure non-periodic unsteady pressure distribution on a wind-tunnel model. A high-speed digital video camera was used to capture the PSP signal. The pressure-sensitive dye was tris(4,7-diphenylphenanthroline) ruthenium(II) ([Ru(dpp)3]2+). The coating has a short response time of O(10 µs), although it exhibits temperature and humidity sensitivities. A hydrophobic coating was applied on the anodized aluminium surface to suppress the humidity sensitivity. A temperature sensitive paint was used to obtain the temperature distribution instantaneously with the pressure. The temperature data were used to correct the PSP response. An appropriate data acquisition procedure as well as digital image processing algorithm was established to compensate for the error from the temperature and humidity sensitivities. The present system was applied to measure the pressure distribution on a delta wing at a high angle of attack in transonic flow, whose flow is unsteady due to the interaction between shock waves and leading edge vortices. The non-periodic unsteady pressure distribution on the delta wing was successfully measured with the sampling rate of 1 kHz and within a few per cent error in absolute pressure level.

  11. Forced and Moment Measurements with Pressure-Sensitive Paint

    NASA Technical Reports Server (NTRS)

    Bell, James H.

    1999-01-01

    The potential of pressure-sensitive paint (PSP) to provide aerodynamic loads measurements has been a driving force behind the development of this measurement technique. To demonstrate the suitability of PSP for this purpose, it is necessary to show that PSP-derived pressures can be accurately integrated over the model surface. This cannot be done simply by demonstrating the accuracy of PSP as compared to pressure taps. PSP errors due to misregistration or temperature sensitivity may be high near model edges, where they will have a strong effect on moment measurements, but where pressure taps are rarely installed. A more suitable technique is to compare integrated PSP data over the entire model surface with balance and/or CFD results. This paper presents results from three experiments in which integrated PSP data is compared with balance and/or CFD data. This allows the usefulness of PSP for force and moment measurements, and by implication for loads measurements, to be assessed.

  12. Enhanced sensitivity of piezoelectric pressure sensor with microstructured polydimethylsiloxane layer

    NASA Astrophysics Data System (ADS)

    Choi, Wook; Lee, Junwoo; Kyoung Yoo, Yong; Kang, Sungchul; Kim, Jinseok; Hoon Lee, Jeong

    2014-03-01

    Highly sensitive detection tools that measure pressure and force are essential in palpation as well as real-time pressure monitoring in biomedical applications. So far, measurement has mainly been done by force sensing resistors and field effect transistor (FET) sensors for monitoring biological pressure and force sensing. We report a pressure sensor by the combination of a piezoelectric sensor layer integrated with a microstructured Polydimethylsiloxane (μ-PDMS) layer. We propose an enhanced sensing tool to be used for analyzing gentle touches without the external voltage source that is used in FET sensors, by incorporating a microstructured PDMS layer in a piezoelectric sensor. By measuring the directly induced electrical charge from the microstructure-enhanced piezoelectric signal, we observed a 3-fold increased sensitivity in a signal response. Both fast signal relaxation from force removal and wide dynamic range from 0.23 to 10 kPa illustrate the good feasibility of the thin film piezoelectric sensor for mimicking human skin.

  13. Process Sensitivity, Performance, and Direct Verification Testing of Adhesive Locking Features

    NASA Technical Reports Server (NTRS)

    Golden, Johnny L.; Leatherwood, Michael D.; Montoya, Michael D.; Kato, Ken A.; Akers, Ed

    2012-01-01

    Phase I: The use of adhesive locking features or liquid locking compounds (LLCs) (e.g., Loctite) as a means of providing a secondary locking feature has been used on NASA programs since the Apollo program. In many cases Loctite was used as a last resort when (a) self-locking fasteners were no longer functioning per their respective drawing specification, (b) access was limited for removal & replacement, or (c) replacement could not be accomplished without severe impact to schedule. Long-term use of Loctite became inevitable in cases where removal and replacement of worn hardware was not cost effective and Loctite was assumed to be fully cured and working. The NASA Engineering & Safety Center (NESC) and United Space Alliance (USA) recognized the need for more extensive testing of Loctite grades to better understand their capabilities and limitations as a secondary locking feature. These tests, identified as Phase I, were designed to identify processing sensitivities, to determine proper cure time, the correct primer to use on aerospace nutplate, insert and bolt materials such as A286 and MP35N, and the minimum amount of Loctite that is required to achieve optimum breakaway torque values. The .1900-32 was the fastener size tested, due to wide usage in the aerospace industry. Three different grades of Loctite were tested. Results indicate that, with proper controls, adhesive locking features can be successfully used in the repair of locking features and should be considered for design. Phase II: Threaded fastening systems used in aerospace programs typically have a requirement for a redundant locking feature. The primary locking method is the fastener preload and the traditional redundant locking feature is a self-locking mechanical device that may include deformed threads, non-metallic inserts, split beam features, or other methods that impede movement between threaded members. The self-locking resistance of traditional locking features can be directly verified

  14. Adhesion improvement of electroless copper plating on phenolic resin matrix composite through a tin-free sensitization process

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Bian, Cheng; Jing, Xinli

    2013-04-01

    In order to improve the adhesion of electroless copper plating on phenolic resin matrix composite (PRMC), a new and efficient tin-free sensitization process has been developed. Electroless copper plating could be achieved in three steps, namely: (i) chemical etching with potassium permanganate solution; (ii) sensitization and activation with glucose and silver nitrate solution respectively; and (iii) electroless copper plating. Compared with the sample sensitized with stannous chloride (SnCl2), the copper plating obtained in the tin-free process showed excellent adhesion with the PRMC substrate, but had lower plating rate and conductivity. Additionally, the morphology of the copper plating was affected by the sensitization process, and the tin-free process was conducive to the formation of the large spherical copper polycrystal. Although the process is slightly complicated, the new sensitization process is so low-cost and environment-friendly that it is of great significance and could be applied into large-scale commercial manufacturing.

  15. Effect of Atmospheric Pressure Plasma Treatment on Surface Characteristics and Adhesive Bond Quality of Peel Ply Prepared Composites

    NASA Astrophysics Data System (ADS)

    Tracey, Ashley C.

    The purpose of this research was to investigate if atmospheric pressure plasma treatment could modify peel ply prepared composite surfaces to create strong adhesive bonds. Two peel ply surface preparation composite systems previously shown to create weak bonds (low fracture energy and adhesion failure) that were potential candidates for plasma treatment were Toray T800/3900-2 carbon fiber reinforced polymer (CFRP) prepared with Precision Fabrics Group, Inc. (PFG) 52006 nylon peel ply and Hexcel T300/F155 CFRP prepared with PFG 60001 polyester peel ply. It was hypothesized that atmospheric pressure plasma treatment could functionalize and/or remove peel ply remnants left on the CFRP surfaces upon peel ply removal. Surface characterization measurements and double cantilever beam (DCB) testing were used to determine the effects of atmospheric pressure plasma treatment on surface characteristics and bond quality of peel ply prepared CFRP composites. Previous research showed that Toray T800/3900-2 carbon fiber reinforced epoxy composites prepared with PFG 52006 peel ply and bonded with Cytec MetlBond 1515-3M structural film adhesive failed in adhesion at low fracture energies when tested in the DCB configuration. Previous research also showed that DCB samples made of Hexcel T300/F155 carbon fiber reinforced epoxy composites prepared with PFG 60001 peel ply and bonded with Henkel Hysol EA 9696 structural film adhesive failed in adhesion at low fracture energies. Recent research suggested that plasma treatment could be able to activate these "un-bondable" surfaces and result in good adhesive bonds. Nylon peel ply prepared 177 °C cure and polyester peel ply prepared 127 °C cure CFRP laminates were treated with atmospheric pressure plasma after peel ply removal prior to bonding. Atmospheric pressure plasma treatment was capable of significantly increasing fracture energies and changing failure modes. For Toray T800/3900-2 laminates prepared with PFG 52006 and bonded with

  16. 75 FR 8114 - Pressure Sensitive Plastic Tape From Italy

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-23

    ..., 2009, the Commission established a schedule for the conduct of the review (74 FR 43155, August 26, 2009... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Pressure Sensitive Plastic Tape From Italy AGENCY: United States International Trade...

  17. High pressure-sensitive gene expression in Lactobacillus sanfranciscensis.

    PubMed

    Vogel, R F; Pavlovic, M; Hörmann, S; Ehrmann, M A

    2005-08-01

    Lactobacillus sanfranciscensis is a Gram-positive lactic acid bacterium used in food biotechnology. It is necessary to investigate many aspects of a model organism to elucidate mechanisms of stress response, to facilitate preparation, application and performance in food fermentation, to understand mechanisms of inactivation, and to identify novel tools for high pressure biotechnology. To investigate the mechanisms of the complex bacterial response to high pressure we have analyzed changes in the proteome and transcriptome by 2-D electrophoresis, and by microarrays and real time PCR, respectively. More than 16 proteins were found to be differentially expressed upon high pressure stress and were compared to those sensitive to other stresses. Except for one apparently high pressure-specific stress protein, no pressure-specific stress proteins were found, and the proteome response to pressure was found to differ from that induced by other stresses. Selected pressure-sensitive proteins were partially sequenced and their genes were identified by reverse genetics. In a transcriptome analysis of a redundancy cleared shot gun library, about 7% of the genes investigated were found to be affected. Most of them appeared to be up-regulated 2- to 4-fold and these results were confirmed by real time PCR. Gene induction was shown for some genes up-regulated at the proteome level (clpL/groEL/rbsK), while the response of others to high hydrostatic pressure at the transcriptome level seemed to differ from that observed at the proteome level. The up-regulation of selected genes supports the view that the cell tries to compensate for pressure-induced impairment of translation and membrane transport. PMID:16082466

  18. Temperature Correction of Pressure-Sensitive Paints Simplified

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy J.

    2000-01-01

    Pressure-sensitive paint (PSP) has become a useful tool to augment conventional pressure taps in measuring the surface pressure distribution of aerodynamic components in wind tunnel testing. Although PSP offers the advantage of nonintrusive global mapping of the surface pressure, one prominent drawback to the accuracy of this technique is the inherent temperature sensitivity of PSP's luminescent intensity. Typical aerodynamic surface PSP tests rely on the coated surface to be both spatially and temporally isothermal, along with conventional instrumentation, to yield the highest accuracy pressure mappings. In some tests, however, spatial and temporal thermal gradients are generated by the nature of the test, as in a blowing jet impinging on a surface. In these cases, high accuracy and reliable data cannot be obtained unless the temperature variations on the painted surface are accounted for. A new temperature-correction technique was developed at the NASA Glenn Research Center at Lewis Field to collapse a "family" of PSP calibration curves to a single curve of intensity ratio versus pressure. This correction allows a streamlined procedure to be followed whether or not temperature information is used in the data reduction of the PSP.

  19. Dynamic Mode Decomposition of Fast Pressure Sensitive Paint Data.

    PubMed

    Ali, Mohd Y; Pandey, Anshuman; Gregory, James W

    2016-01-01

    Fast-response pressure sensitive paint (PSP) is used in this work to measure and analyze the acoustic pressure field in a rectangular cavity. The high spatial resolution and fast frequency response of PSP effectively captures the spatial and temporal detail of surface pressure resulting in the acoustic pressure field. In this work, a high-speed camera is used to generate a continuous time record of the acoustic pressure fluctuations with PSP. Since the level of the acoustic pressure is near the resolution limit of the sensor system, advanced analysis techniques are used to extract the spatial modes of the pressure field. Both dynamic mode decomposition (DMD) and proper orthogonal decomposition (POD) are compared with phase averaging for data analysis. While all three techniques effectively extract the pressure field and reduce the impact of sensor noise, DMD and POD are more robust techniques that can be applied to aperiodic or multi-frequency signals. Furthermore, DMD is better than POD at suppressing noise in particular regions of the spectrum and at effectively separating spectral energy when multiple acoustic excitation frequencies are present. PMID:27294939

  20. Dynamic Mode Decomposition of Fast Pressure Sensitive Paint Data

    PubMed Central

    Ali, Mohd Y.; Pandey, Anshuman; Gregory, James W.

    2016-01-01

    Fast-response pressure sensitive paint (PSP) is used in this work to measure and analyze the acoustic pressure field in a rectangular cavity. The high spatial resolution and fast frequency response of PSP effectively captures the spatial and temporal detail of surface pressure resulting in the acoustic pressure field. In this work, a high-speed camera is used to generate a continuous time record of the acoustic pressure fluctuations with PSP. Since the level of the acoustic pressure is near the resolution limit of the sensor system, advanced analysis techniques are used to extract the spatial modes of the pressure field. Both dynamic mode decomposition (DMD) and proper orthogonal decomposition (POD) are compared with phase averaging for data analysis. While all three techniques effectively extract the pressure field and reduce the impact of sensor noise, DMD and POD are more robust techniques that can be applied to aperiodic or multi-frequency signals. Furthermore, DMD is better than POD at suppressing noise in particular regions of the spectrum and at effectively separating spectral energy when multiple acoustic excitation frequencies are present. PMID:27294939

  1. Influence of genetic variance on sodium sensitivity of blood pressure.

    PubMed

    Luft, F C; Miller, J Z; Weinberger, M H; Grim, C E; Daugherty, S A; Christian, J C

    1987-02-01

    To examine the effect of genetic variance on blood pressure, sodium homeostasis, and its regulatory determinants, we studied 37 pairs of monozygotic twins and 18 pairs of dizygotic twins under conditions of volume expansion and contraction. We found that, in addition to blood pressure and body size, sodium excretion in response to provocative maneuvers, glomerular filtration rate, the renin-angiotensin system, and the sympathetic nervous system are influenced by genetic variance. To elucidate the interaction of genetic factors and an environmental influence, namely, salt intake, we restricted dietary sodium in 44 families of twin children. In addition to a modest decrease in blood pressure, we found heterogeneous responses in blood pressure indicative of sodium sensitivity and resistance which were normally distributed. Strong parent-offspring resemblances were found in baseline blood pressures which persisted when adjustments were made for age and weight. Further, mother-offspring resemblances were observed in the change in blood pressure with sodium restriction. We conclude that the control of sodium homeostasis is heritable and that the change in blood pressure with sodium restriction is familial as well. These data speak to the interaction between the genetic susceptibility to hypertension and environmental influences which may result in its expression. PMID:3553721

  2. Effect of pretreatment methods and chamber pressure on morphology, quality and adhesion of HFCVD diamond coating on cemented carbide inserts

    NASA Astrophysics Data System (ADS)

    Sarangi, S. K.; Chattopadhyay, A.; Chattopadhyay, A. K.

    2008-04-01

    In the present investigation, diamond coating was deposited on cemented carbide substrate by hot filament chemical vapour deposition. The effect of substrate pretreatment methods and chamber pressure on morphology, quality, and adhesion of the diamond film were studied. The carbide inserts were pretreated with acid, Murakami's solution, and Murakami's solution followed by acid, respectively. The chamber pressure was set at 6.6, 13.2, 26.4, 39.6 and 66 mbar. Deposition carried out at pressure of 26.4 and 39.6 mbar on inserts pretreated with acid exhibited uniform crystal habit and provided coating-substrate adhesion adequate for machining application. Good coating morphology was obtained when deposition was done at 6.6 mbar on carbide inserts treated with Murakami's solution. Pretreatment with Murakami's solution followed by acid and deposition at 6.6 mbar also resulted in good morphology of diamond film. Indentation (Rockwell C scale) was done on diamond-coated inserts to assess coating-substrate adhesion under three loads of 294, 588 and 980 N. The diameter of the indentation crack at the coating-substrate interface was observed under SEM. The results suggested that diamond coating deposited at medium pressure of 26.4 mbar on carbide substrate treated with acid not only exhibited best morphology but also highest coating-substrate adhesion and improved machining performance.

  3. Applying Pressure Sensitive Paint Technology to Rotor Blades

    NASA Technical Reports Server (NTRS)

    Watkins, A. Neal; Leighty, Bradley D.; Lipford, William E.; Goodman, Kyle Z.; Crafton, Jim; Gregory, James W.

    2014-01-01

    This report will present details of a Pressure Sensitive Paint (PSP) system for measuring global surface pressures on rotorcrtaft blades in simulated forward flight at the 14- by 22-Foot Subsonic Tunnel at the NASA Langley Research Center. The basics of the PSP method will be discussed and the modifications that were needed to extend this technology for use on rotor blades. Results from a series of tests will also be presented as well as several areas of improvement that have been identified and are currently being developed for future testing.

  4. Langley 16- Ft. Transonic Tunnel Pressure Sensitive Paint System

    NASA Technical Reports Server (NTRS)

    Sprinkle, Danny R.; Obara, Clifford J.; Amer, Tahani R.; Leighty, Bradley D.; Carmine, Michael T.; Sealey, Bradley S.; Burkett, Cecil G.

    2001-01-01

    This report describes the NASA Langley 16-Ft. Transonic Tunnel Pressure Sensitive Paint (PSP) System and presents results of a test conducted June 22-23, 2000 in the tunnel to validate the PSP system. The PSP system provides global surface pressure measurements on wind tunnel models. The system was developed and installed by PSP Team personnel of the Instrumentation Systems Development Branch and the Advanced Measurement and Diagnostics Branch. A discussion of the results of the validation test follows a description of the system and a description of the test.

  5. Imperfection sensitivity of pressured buckling of biopolymer spherical shells

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Ru, C. Q.

    2016-06-01

    Imperfection sensitivity is essential for mechanical behavior of biopolymer shells [such as ultrasound contrast agents (UCAs) and spherical viruses] characterized by high geometric heterogeneity. In this work, an imperfection sensitivity analysis is conducted based on a refined shell model recently developed for spherical biopolymer shells of high structural heterogeneity and thickness nonuniformity. The influence of related parameters (including the ratio of radius to average shell thickness, the ratio of transverse shear modulus to in-plane shear modulus, and the ratio of effective bending thickness to average shell thickness) on imperfection sensitivity is examined for pressured buckling. Our results show that the ratio of effective bending thickness to average shell thickness has a major effect on the imperfection sensitivity, while the effect of the ratio of transverse shear modulus to in-plane shear modulus is usually negligible. For example, with physically realistic parameters for typical imperfect spherical biopolymer shells, the present model predicts that actual maximum external pressure could be reduced to as low as 60% of that of a perfect UCA spherical shell or 55%-65% of that of a perfect spherical virus shell, respectively. The moderate imperfection sensitivity of spherical biopolymer shells with physically realistic imperfection is largely attributed to the fact that biopolymer shells are relatively thicker (defined by smaller radius-to-thickness ratio) and therefore practically realistic imperfection amplitude normalized by thickness is very small as compared to that of classical elastic thin shells which have much larger radius-to-thickness ratio.

  6. Promotion of adhesive penetration and resin bond strength to dentin using non-thermal atmospheric pressure plasma.

    PubMed

    Kim, Jae-Hoon; Han, Geum-Jun; Kim, Chang-Keun; Oh, Kyu-Hwan; Chung, Sung-No; Chun, Bae-Hyeock; Cho, Byeong-Hoon

    2016-02-01

    Non-thermal atmospheric pressure plasmas (NT-APPs) have been shown to improve the bond strength of resin composites to demineralized dentin surfaces. Based on a wet-bonding philosophy, it is believed that a rewetting procedure is necessary after treatment with NT-APP because of its air-drying effect. This study investigated the effect of 'plasma-drying' on the bond strength of an etch-and-rinse adhesive to dentin by comparison with the wet-bonding technique. Dentin surfaces of human third molars were acid-etched and divided into four groups according to the adhesion procedure: wet bonding, plasma-drying, plasma-drying/rewetting, and dry bonding. In plasma treatment groups, the demineralized dentin surfaces were treated with a plasma plume generated using a pencil-type low-power plasma torch. After the adhesion procedures, resin composite/dentin-bonded specimens were subjected to a microtensile bond-strength test. The hybrid layer formation was characterized by micro-Raman spectroscopy and scanning electron microscopy. The plasma-drying group presented significantly higher bond strength than the wet-bonding and dry-bonding groups. Micro-Raman spectral analysis indicated that plasma-drying improved the penetration and polymerization efficacy of the adhesive. Plasma-drying could be a promising method to control the moisture of demineralized dentin surfaces and improve the penetration of adhesive and the mechanical property of the adhesive/dentin interface. PMID:26714586

  7. A novel high-sensitivity FBG pressure sensor

    NASA Astrophysics Data System (ADS)

    Yao, Zhenhua; Fu, Tao; Leng, Jinsong

    2007-07-01

    A novel pressure sensor based on FBG is designed in this paper. Not only in normal environment, also does it accurately work in water and petrol where other conventional sensors can not work normally. In this paper, the principle of the novel sensor is introduced, and two experiments are further performed: One is keeping the sensor flatly in the gastight silo whose pressure is supplied by an air compressing engine, and the other one is keeping the sensor in liquid. The analysis of the result data demonstrates that the sensor possesses high sensitivity, high linearity, high precision and repeatability. Its experimental linearity and sensitivity approach 0.99858 and 5.35×10 -3MPa -1, respectively. It is also discussed using the sensor to measure the volume in tank.

  8. Polymer-Particle Pressure-Sensitive Paint with High Photostability.

    PubMed

    Matsuda, Yu; Uchida, Kenta; Egami, Yasuhiro; Yamaguchi, Hiroki; Niimi, Tomohide

    2016-01-01

    We propose a novel fast-responding and paintable pressure-sensitive paint (PSP) based on polymer particles, i.e. polymer-particle (pp-)PSP. As a fast-responding PSP, polymer-ceramic (PC-)PSP is widely studied. Since PC-PSP generally consists of titanium (IV) oxide (TiO₂) particles, a large reduction in the luminescent intensity will occur due to the photocatalytic action of TiO₂. We propose the usage of polymer particles instead of TiO₂ particles to prevent the reduction in the luminescent intensity. Here, we fabricate pp-PSP based on the polystyrene particle with a diameter of 1 μm, and investigate the pressure- and temperature-sensitives, the response time, and the photostability. The performances of pp-PSP are compared with those of PC-PSP, indicating the high photostability with the other characteristics comparable to PC-PSP. PMID:27092511

  9. Polymer-Particle Pressure-Sensitive Paint with High Photostability

    PubMed Central

    Matsuda, Yu; Uchida, Kenta; Egami, Yasuhiro; Yamaguchi, Hiroki; Niimi, Tomohide

    2016-01-01

    We propose a novel fast-responding and paintable pressure-sensitive paint (PSP) based on polymer particles, i.e. polymer-particle (pp-)PSP. As a fast-responding PSP, polymer-ceramic (PC-)PSP is widely studied. Since PC-PSP generally consists of titanium (IV) oxide (TiO2) particles, a large reduction in the luminescent intensity will occur due to the photocatalytic action of TiO2. We propose the usage of polymer particles instead of TiO2 particles to prevent the reduction in the luminescent intensity. Here, we fabricate pp-PSP based on the polystyrene particle with a diameter of 1 μm, and investigate the pressure- and temperature-sensitives, the response time, and the photostability. The performances of pp-PSP are compared with those of PC-PSP, indicating the high photostability with the other characteristics comparable to PC-PSP. PMID:27092511

  10. A highly sensitive and flexible pressure sensor with electrodes and elastomeric interlayer containing silver nanowires

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Jiu, Jinting; Nogi, Masaya; Sugahara, Tohru; Nagao, Shijo; Koga, Hirotaka; He, Peng; Suganuma, Katsuaki

    2015-02-01

    The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present study a simple printing process without complex patterning has been used for constructing the sensor, and an interlayer is employed comprising elastomeric composites filled with silver nanowires. By increasing the relative permittivity, εr, of the composite interlayer induced by compression at high nanowire concentration, it has been possible to achieve a maximum sensitivity of 5.54 kPa-1. The improvement in sensitivity did not sacrifice or undermine the other features of the sensor. Thanks to the silver nanowire electrodes, the sensor is flexible and stable after 200 cycles at a bending radius of 2 mm, and exhibits outstanding reproducibility without hysteresis under similar pressure pulses. The sensor has been readily integrated onto an adhesive bandage and has been successful in detecting human movements. In addition to measuring pressure in direct contact, non-contact pressures such as air flow can also be detected.The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present

  11. Pressure Sensitive Tape in the Manufacture of Reusable Solid Rocket Motors

    NASA Technical Reports Server (NTRS)

    Champneys, Jeff

    2007-01-01

    ATK Launch Systems Inc. manufactures the reusable solid rocket motor (RSRM) for NASA's Space Shuttle program. They are used in pairs to launch the Space Shuttle. Pressure sensitive tape (PST) is used throughout the RSRM manufacturing process. A few PST functions are: 1) Secure labels; 2) Provide security seals; and 3) Protect tooling and flight hardware during various inert and live operations. Some of the PSTs used are: Cloth, Paper, Reinforced Teflon, Double face, Masking, and Vinyl. Factors given consideration for determining the type of tape to be used are: 1) Ability to hold fast; 2) Ability to release easily; 3) Ability to endure abuse; 4) Strength; and 5) Absence of adhesive residue after removal.

  12. Improvement of Si Adhesion and Reduction of Electron Recombination for Si Quantum Dot-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Seo, Hyunwoong; Wang, Yuting; Sato, Muneharu; Uchida, Giichiro; Kamataki, Kunihiro; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

    2013-01-01

    Quantum dots (QDs) based on multiple exciton generation have attracted much attention. They are capable of generating multiple electrons by single-photon absorption. Si is one of the good QD sources and its nontoxicity and abundance are advantageous for photovoltaics. In this work, Si QDs were fabricated by multihollow discharge plasma chemical vapor deposition, and they were applied to Si QD-sensitized solar cells. Their initial performance was poor because of the weak adhesion of Si and charge recombination. In this work, we solved these problems through the functionalization of Si QDs and a ZnO barrier. Functionalized Si QDs were more adsorbed on TiO2 with strengthened adhesion and the ZnO barrier prevented the contact between TiO2 and the redox electrolyte. Consequently, the improved adhesion and the reduced electron recombination led to the enhancement of overall photovoltaic characteristics.

  13. Development of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades

    NASA Technical Reports Server (NTRS)

    Watkins, A. Neal; Leighty, Bradley D.; Lipford, William E.; Wong, Oliver D.; Oglesby, Donald M.; Ingram, JoAnne L.

    2007-01-01

    This paper will describe the results from a proof of concept test to examine the feasibility of using Pressure Sensitive Paint (PSP) to measure global surface pressures on rotorcraft blades in hover. The test was performed using the U.S. Army 2-meter Rotor Test Stand (2MRTS) and 15% scale swept rotor blades. Data were collected from five blades using both the intensity- and lifetime-based approaches. This paper will also outline several modifications and improvements that are underway to develop a system capable of measuring pressure distributions on up to four blades simultaneously at hover and forward flight conditions.

  14. Characteristics of Pressure Sensitive Paint Intrusiveness Effects on Aerodynamic Data

    NASA Technical Reports Server (NTRS)

    Amer, Tahani R.; Liu, Tianshu; Oglesby, Donald M.

    2001-01-01

    One effect of using pressure sensitive paint (PSP) is the potential intrusiveness to the aerodynamic characteristics of the model. The paint thickness and roughness may affect the pressure distribution, and therefore, the forces and moments on the wind tunnel model. A study of these potential intrusive effects was carried out at NASA Langley Research Center where a series of wind tunnel tests were conducted using the Modem Design of Experiments (MDOE) test approach. The PSP effects on the integrated forces were measured on two different models at different test conditions in both the Low Turbulence Pressure Tunnel (LTPT) and the Unitary Plan Wind Tunnel (UPWT) at Langley. The paint effect was found to be very small over a range of Reynolds numbers, Mach numbers and angles of attack. This is due to the very low surface roughness of the painted surface. The surface roughness, after applying the NASA Langley developed PSP, was lower than that of the clean wing. However, the PSP coating had a localized effects on the pressure taps, which leads to an appreciable decrease in the pressure tap reading.

  15. Characterization of Pressure Sensitive Paint Intrusiveness Effects on Aerodynamic Data

    NASA Technical Reports Server (NTRS)

    Amer, Tahani R.; Liu, Tianshu; Oglesby, Donald M.

    2001-01-01

    One effect of using pressure sensitive paint (PSP) is the potential intrusiveness to the aerodynamic characteristics of the model. The paint thickness and roughness may affect the pressure distribution. and therefore, the forces and moments on the wind tunnel model. A study of these potential intrusive effects was carried out at NASA Langley Research Center where a series of wind tunnel tests were conducted using the Modem Design of Experiments (MDOE) test approach. The PSP effects on the integrated forces were measured on two different models at different test conditions in both the Low Turbulence Pressure Tunnel (LTPT) and the Unitary Plan Wind Tunnel (UPWT) at Langley. The paint effect was found to be very small over a range of Reynolds numbers, Mach numbers and angles of attack. This is due to the very low surface roughness of the painted surface. The surface roughness, after applying the NASA Langley developed PSP, was lower than that of the clean wing. However, the PSP coating had a localized effects on the pressure taps, which leads to an appreciable decrease in the pressure tap reading.

  16. Effect of atmospheric pressure plasma treatment condition on adhesion of ramie fibers to polypropylene for composite

    NASA Astrophysics Data System (ADS)

    Li, Ying; Manolache, Sorin; Qiu, Yiping; Sarmadi, Majid

    2016-02-01

    In order to improve the interfacial adhesion between hydrophilic ramie fibers and hydrophobic polypropylene (PP) matrices, ramie fibers are modified by atmospheric pressure dielectric barrier discharge (DBD) plasma with our continuous ethanol flow technique in helium environment. A central composite design of experiments with different plasma processing parameter combinations (treatment current, treatment time and ethanol flow rate) is applied to find the most influential parameter and to obtain the best modification effect. Field emission scanning electron microscope (SEM) shows the roughened surfaces of ramie fibers from the treated groups due to plasma etching effect. Dynamic contact angle analysis (DCAA) demonstrates that the wettability of the treated fibers drastically decreases. Microbond pullout test shows that the interfacial shear strength (IFSS) between treated ramie fibers and PP matrices increases significantly. Residual gas analysis (RGA) confirms the creation of ethyl groups during plasma treatment. This study shows that our continuous ethanol flow technique is effective in the plasma modification process, during which the ethanol flow rate is the most influential parameter but all parameters have simultaneous influence on plasma modification effect of ramie fibers.

  17. A highly sensitive fiber Bragg grating diaphragm pressure transducer

    NASA Astrophysics Data System (ADS)

    Allwood, Gary; Wild, Graham; Lubansky, Alex; Hinckley, Steven

    2015-10-01

    In this work, a novel diaphragm based pressure transducer with high sensitivity is described, including the physical design structure, in-depth analysis of optical response to changes in pressure, and a discussion of practical implementation and limitations. A flat circular rubber membrane bonded to a cylinder forms the body of the transducer. A fiber Bragg grating bonded to the center of the diaphragm structure enables the fractional change in pressure to be determined by analyzing the change in Bragg wavelength of the reflected spectra. Extensive evaluation of the physical properties and optical characteristics of the transducer has been performed through experimentation, and modeling using small deformation theory. The results show the transducer has a sensitivity of 0.116 nm/kPa, across a range of 15 kPa. Ultra-low cost interrogation of the optical signal was achieved through the use of an optically mismatched Bragg grating acting as an edge filter to convert the spectral change into an intensity change. A numerical model of the intensity based interrogation was implemented in order to validate the experimental results. Utilizing this interrogation technique and housing both the sensing and reference Bragg gratings within the main body of the transducer means it is effectively temperature insensitive and easily connected to electronic systems.

  18. Plasma treatment of poly(dimethylsiloxane) surfaces using a compact atmospheric pressure dielectric barrier discharge device for adhesion improvement

    NASA Astrophysics Data System (ADS)

    do Nascimento, Fellype; Parada, Sergio; Moshkalev, Stanislav; Machida, Munemasa

    2016-02-01

    Results of the treatment of poly(dimethylsiloxane) (PDMS) surfaces using novel atmospheric pressure pulsed dielectric barrier discharge plasmas are presented. Different gases (argon, helium, nitrogen) as well as their mixtures with water vapor were compared in terms of the improvement of adhesion between two PDMS samples after processing by plasma. The plasma was characterized by optical emission spectroscopy to identify the emitting species and determine the plasma temperatures. For all the gases studied, plasma processing resulted in increase of adhesion between PDMS samples if long exposure time (larger than 150 s) is applied. However, for very short treatment times (20 plasma pulses, total processing time about 3 s) the highest efficiency was found for helium plasmas. Water contact angles at PDMS surfaces as function of plasma processing time was analyzed. Atomic force microscopy analysis was performed to show reduction in the surface roughness after plasma treatment, which is likely to be the responsible for increase of the surface contact area and thus the adhesion between two PDMS surfaces. The role of the two mechanisms in the improvement of adhesion (enhanced wettability and changes in the surface morphology), for different time scales, is discussed. Interestingly, for the minimum processing time (20 plasma pulses), the improvement in adhesion and reduction of surface roughness are observed although the changes in the water contact angle are insignificant.

  19. Superconducting Accelerating Cavity Pressure Sensitivity Analysis and Stiffening

    SciTech Connect

    Rodnizki, J; Ben Aliz, Y; Grin, A; Horvitz, Z; Perry, A; Weissman, L; Davis, G Kirk; Delayen, Jean R.

    2014-12-01

    The Soreq Applied Research Accelerator Facility (SARAF) design is based on a 40 MeV 5 mA light ions superconducting RF linac. Phase-I of SARAF delivers up to 2 mA CW proton beams in an energy range of 1.5 - 4.0 MeV. The maximum beam power that we have reached is 5.7 kW. Today, the main limiting factor to reach higher ion energy and beam power is related to the HWR sensitivity to the liquid helium coolant pressure fluctuations. The HWR sensitivity to helium pressure is about 60 Hz/mbar. The cavities had been designed, a decade ago, to be soft in order to enable tuning of their novel shape. However, the cavities turned out to be too soft. In this work we found that increasing the rigidity of the cavities in the vicinity of the external drift tubes may reduce the cavity sensitivity by a factor of three. A preliminary design to increase the cavity rigidity is presented.

  20. Sensitivity of Pressure Sensors Enhanced by Doping Silver Nanowires

    PubMed Central

    Li, Baozhang; Xu, Chengyi; Zheng, Jianming; Xu, Chunye

    2014-01-01

    We have developed a highly sensitive flexible pressure sensor based on a piezopolymer and silver nanowires (AgNWs) composite. The composite nanofiber webs are made by electrospinning mixed solutions of poly(inylidene fluoride) (PVDF) and Ag NWs in a cosolvent mixture of dimethyl formamide and acetone. The diameter of the fibers ranges from 200 nm to 500 nm, as demonstrated by SEM images. FTIR and XRD results reveal that doping Ag NWs into PVDF greatly enhances the content of β phase in PVDF. This β phase increase can be attributed to interactions between the Ag NWs and the PVDF matrix, which forces the polymer chains to be embedded into the β phase crystalline. The sensitivity of the pressure sensors agrees well with the FTIR and XRD characteristics. In our experiments, the measured sensitivity reached up to 30 pC/N for the nanofiber webs containing 1.5 wt% Ag NWs, which is close to that of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE), (77/23)]. This study may provide a new method of fabricating high performance flexible sensors at relatively low cost compared with sensors based on [P(VDF-TrFE), (77/23)]. PMID:24901980

  1. A Graphene-Based Resistive Pressure Sensor with Record-High Sensitivity in a Wide Pressure Range

    NASA Astrophysics Data System (ADS)

    Tian, He; Shu, Yi; Wang, Xue-Feng; Mohammad, Mohammad Ali; Bie, Zhi; Xie, Qian-Yi; Li, Cheng; Mi, Wen-Tian; Yang, Yi; Ren, Tian-Ling

    2015-02-01

    Pressure sensors are a key component in electronic skin (e-skin) sensing systems. Most reported resistive pressure sensors have a high sensitivity at low pressures (<5 kPa) to enable ultra-sensitive detection. However, the sensitivity drops significantly at high pressures (>5 kPa), which is inadequate for practical applications. For example, actions like a gentle touch and object manipulation have pressures below 10 kPa, and 10-100 kPa, respectively. Maintaining a high sensitivity in a wide pressure range is in great demand. Here, a flexible, wide range and ultra-sensitive resistive pressure sensor with a foam-like structure based on laser-scribed graphene (LSG) is demonstrated. Benefitting from the large spacing between graphene layers and the unique v-shaped microstructure of the LSG, the sensitivity of the pressure sensor is as high as 0.96 kPa-1 in a wide pressure range (0 ~ 50 kPa). Considering both sensitivity and pressure sensing range, the pressure sensor developed in this work is the best among all reported pressure sensors to date. A model of the LSG pressure sensor is also established, which agrees well with the experimental results. This work indicates that laser scribed flexible graphene pressure sensors could be widely used for artificial e-skin, medical-sensing, bio-sensing and many other areas.

  2. A Graphene-Based Resistive Pressure Sensor with Record-High Sensitivity in a Wide Pressure Range

    PubMed Central

    Tian, He; Shu, Yi; Wang, Xue-Feng; Mohammad, Mohammad Ali; Bie, Zhi; Xie, Qian-Yi; Li, Cheng; Mi, Wen-Tian; Yang, Yi; Ren, Tian-Ling

    2015-01-01

    Pressure sensors are a key component in electronic skin (e-skin) sensing systems. Most reported resistive pressure sensors have a high sensitivity at low pressures (<5 kPa) to enable ultra-sensitive detection. However, the sensitivity drops significantly at high pressures (>5 kPa), which is inadequate for practical applications. For example, actions like a gentle touch and object manipulation have pressures below 10 kPa, and 10–100 kPa, respectively. Maintaining a high sensitivity in a wide pressure range is in great demand. Here, a flexible, wide range and ultra-sensitive resistive pressure sensor with a foam-like structure based on laser-scribed graphene (LSG) is demonstrated. Benefitting from the large spacing between graphene layers and the unique v-shaped microstructure of the LSG, the sensitivity of the pressure sensor is as high as 0.96 kPa−1 in a wide pressure range (0 ~ 50 kPa). Considering both sensitivity and pressure sensing range, the pressure sensor developed in this work is the best among all reported pressure sensors to date. A model of the LSG pressure sensor is also established, which agrees well with the experimental results. This work indicates that laser scribed flexible graphene pressure sensors could be widely used for artificial e-skin, medical-sensing, bio-sensing and many other areas. PMID:25721159

  3. Nanorod-Based Fast-Response Pressure-Sensitive Paints

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy; VanderWal, Randall

    2007-01-01

    forms, by use of chemical vapor deposition (CVD) and wet chemical processes, respectively. The rods would be coated with a PSP dye, and the resulting PSP signals would be compared with those obtained from PSP dye coats on conventional support materials. Another aspect of the proposed development would be to seek to exploit the quantum properties of nanorods of a suitable semiconductor (possibly GaN), which would be synthesized by CVD. These quantum properties of semiconductor nanorods include narrow-wavelength-band optical absorption and emission characteristics that vary with temperature. The temperature sensitivity might enable simultaneous measurement of fluctuating temperature and pressure and to provide a temperature correction for the PSP response.

  4. Vibration isolation and pressure compensation apparatus for sensitive instrumentation

    NASA Technical Reports Server (NTRS)

    Averill, R. D. (Inventor)

    1983-01-01

    A system for attenuating the inherent vibration associated with a mechanical refrigeration unit employed to cryogenically cool sensitive instruments used in measuring chemical constituents of the atmosphere is described. A modular system including an instrument housing and a reaction bracket with a refrigerator unit floated there between comprise the instrumentation system. A pair of evacuated bellows that "float' refrigerator unit and provide pressure compensation at all levels of pressure from seal level to the vacuum of space. Vibration isolators and when needed provide additional vibration damping for the refrigerator unit. A flexible thermal strap (20 K) serves to provide essentially vibration free thermal contact between cold tip of the refrigerator unit and the instrument component mounted on the IDL mount. Another flexible strap (77 K) serves to provide vibration free thermal contact between the TDL mount thermal shroud and a thermal shroud disposed about the thermal shaft.

  5. Development of electroluminescence based pressure-sensitive paint system.

    PubMed

    Iijima, Yoshimi; Sakaue, Hirotaka

    2011-01-01

    We introduce a pressure-sensitive paint (PSP) measurement system based on an electroluminescence (EL) as a surface illumination. This consists of an inorganic EL as the illumination, a short-pass filter, and a platinum-porphyrin based PSP. The short-pass filter, which passes below 500 nm, was used to separate an overlay of the EL illumination and the PSP emission. The EL shows an opposite temperature dependency to that of the PSP. It gives a uniform illumination compared to that of a point illumination source such as a xenon lamp. Under atmospheric conditions, the resultant EL-PSP system reduces the temperature dependency by 54% compared to that of a conventional PSP system. An application of the EL-PSP system to a sonic jet impingement shows that the system demonstrated its reduction of the temperature dependency by 75% in a pressure measurement and reduces an image misalignment error. PMID:21280858

  6. Detection Angle Calibration of Pressure-Sensitive Paints

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy J.

    2000-01-01

    Uses of the pressure-sensitive paint (PSP) techniques in areas other than external aerodynamics continue to expand. The NASA Glenn Research Center has become a leader in the application of the global technique to non-conventional aeropropulsion applications including turbomachinery testing. The use of the global PSP technique in turbomachinery applications often requires detection of the luminescent paint in confined areas. With the limited viewing usually available, highly oblique illumination and detection angles are common in the confined areas in these applications. This paper will describe the results of pressure, viewing and excitation angle dependence calibrations using three popular PSP formulations to get a better understanding of the errors associated with these non-traditional views.

  7. Diffusion Time-Scale of Porous Pressure-Sensitive Paint

    NASA Technical Reports Server (NTRS)

    Liu, Tianshu; Teduka, Norikazu; Kameda, Masaharu; Asai, Keisuke

    2001-01-01

    Pressure-sensitive paint (PSP) is an optical pressure sensor that utilizes the oxygen quenching of luminescence. PSP measurements in unsteady aerodynamic flows require fast time response of the paint. There are two characteristic time-scales that are related to the time response of PSP. One is the luminescent lifetime representing an intrinsic physical limit for the achievable temporal resolution of PSP. Another is the time-scale of oxygen diffusion across the PSP layer. When the time-scale of oxygen diffusion is much larger than the luminescent lifetime, the time response of PSP is controlled by oxygen diffusion. In a thin homogenous polymer layer where diffusion is Fickian, the oxygen concentration 1021 can be described by the diffusion equation in one-dimension.

  8. Quantifying the Effect of Pressure Sensitive Paint On Aerodynamic Data

    NASA Technical Reports Server (NTRS)

    Amer, T. R.; Obara, C. J.; Liu, T.

    2003-01-01

    A thin pressure sensitive paint (PSP) coating can slightly modify the overall shape of a wind-tunnel model and produce surface roughness or smoothness that does not exist on the unpainted model. These undesirable changes in model geometry may alter flow over the model, and affect the pressure distribution and aerodynamic forces and moments on the model. This study quantifies the effects of PSP on three models in low-speed, transonic and supersonic flow regimes. At a 95% confidence level, the PSP effects on the integrated forces are insignificant for a slender arrow-wing-fuselage model and delta wing model with two different paints at Mach 0.2, 1.8, and 2.16 relative to the total balance accuracy limit. The data displayed a repeatability of 2.5 drag counts, while the balance accuracy limit was about 5.5 drag counts. At transonic speeds, the paint has a localized effect at high angles of attack and has a resolvable effect on the normal force, which is significant relative to the balance accuracy limit. For low speeds, the PSP coating has a localized effect on the pressure tap measurements, which leads to an appreciable decrease in the pressure tap reading. Moreover, the force and moment measurements had a poor precision, which precluded the ability to measure the PSP effect for this particular test.

  9. Measuring Surface Pressure on Rotating Compressor Blades Using Pressure Sensitive Paint.

    PubMed

    Pastuhoff, Markus; Tillmark, Nils; Alfredsson, P Henrik

    2016-01-01

    Pressure sensitive paint (PSP) was used to measure pressure on the blades of a radial compressor with a 51 mm inlet diameter rotating at speeds up to 50 krpm using the so called lifetime method. A diode laser with a scanning-mirror system was used to illuminate the paint and the luminescent lifetime was registered using a photo multiplier. With the described technique the surface-pressure fields were acquired for eight points in the compressor map, useful for general understanding of the flow field and for CFD validation. The PSP was of so called fast type, which makes it possible to observe pressure variations with frequencies up to several kHz. Through frequency spectrum analysis we were able to detect the pulsating flow frequency when the compressor was driven to surge. PMID:27005623

  10. Measuring Surface Pressure on Rotating Compressor Blades Using Pressure Sensitive Paint

    PubMed Central

    Pastuhoff, Markus; Tillmark, Nils; Alfredsson, P. Henrik

    2016-01-01

    Pressure sensitive paint (PSP) was used to measure pressure on the blades of a radial compressor with a 51 mm inlet diameter rotating at speeds up to 50 krpm using the so called lifetime method. A diode laser with a scanning-mirror system was used to illuminate the paint and the luminescent lifetime was registered using a photo multiplier. With the described technique the surface-pressure fields were acquired for eight points in the compressor map, useful for general understanding of the flow field and for CFD validation. The PSP was of so called fast type, which makes it possible to observe pressure variations with frequencies up to several kHz. Through frequency spectrum analysis we were able to detect the pulsating flow frequency when the compressor was driven to surge. PMID:27005623

  11. Pressure-Sensitive Paints Advance Rotorcraft Design Testing

    NASA Technical Reports Server (NTRS)

    2013-01-01

    The rotors of certain helicopters can spin at speeds as high as 500 revolutions per minute. As the blades slice through the air, they flex, moving into the wind and back out, experiencing pressure changes on the order of thousands of times a second and even higher. All of this makes acquiring a true understanding of rotorcraft aerodynamics a difficult task. A traditional means of acquiring aerodynamic data is to conduct wind tunnel tests using a vehicle model outfitted with pressure taps and other sensors. These sensors add significant costs to wind tunnel testing while only providing measurements at discrete locations on the model's surface. In addition, standard sensor solutions do not work for pulling data from a rotor in motion. "Typical static pressure instrumentation can't handle that," explains Neal Watkins, electronics engineer in Langley Research Center s Advanced Sensing and Optical Measurement Branch. "There are dynamic pressure taps, but your costs go up by a factor of five to ten if you use those. In addition, recovery of the pressure tap readings is accomplished through slip rings, which allow only a limited amount of sensors and can require significant maintenance throughout a typical rotor test." One alternative to sensor-based wind tunnel testing is pressure sensitive paint (PSP). A coating of a specialized paint containing luminescent material is applied to the model. When exposed to an LED or laser light source, the material glows. The glowing material tends to be reactive to oxygen, explains Watkins, which causes the glow to diminish. The more oxygen that is present (or the more air present, since oxygen exists in a fixed proportion in air), the less the painted surface glows. Imaged with a camera, the areas experiencing greater air pressure show up darker than areas of less pressure. "The paint allows for a global pressure map as opposed to specific points," says Watkins. With PSP, each pixel recorded by the camera becomes an optical pressure

  12. 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.

  13. Ultrafast pressure-sensitive paint for shock compression spectroscopy

    NASA Astrophysics Data System (ADS)

    Banishev, Alexandr A.; Dlott, Dana D.

    2014-05-01

    A pressure-sensitive paint (PSP) consisting of rhodamine 6G (R6G) dye in poly-methylacryate (PMMA) polymer is studied during nanosecond GPa shock compression created by km s-1 laser-launched layer plates. In contrast with conventional PSP, whose response time is limited to microseconds by diffusion of O2 in porous materials, the response time of this PSP is limited to ˜10 ns by fundamental photophysical processes. The mechanism of shock-induced PSP intensity loss is shown to be shock-enhanced intersystem crossing, which transfers some R6G population from the emissive S1 state to the dark T1 state. Simulations of dye photophysics and comparisons to experiment show that the PSP is sensitive to the complicated time-dependent density profiles produced in PMMA by different duration shocks. The risetime of the PSP response is limited by the S1 lifetime under shock compression. The fall time is limited by the T1 lifetime, which can be decreased by adding triplet quenchers. The PSP can function in two modes. When dissolved O2 (a triplet quencher) was eliminated, the fall time became relatively slow (microseconds), and the PSP sampled the peak shock pressure and held that value for a long time. When dissolved O2 was present, the intensity loss recovery became faster, so the PSP could function as a transient recorder of the shock-induced time-dependent density profile.

  14. Deformation of rock: A pressure-sensitive, dilatant material

    NASA Astrophysics Data System (ADS)

    Ord, A.

    1991-12-01

    Permanent (plastic) deformation of rock materials in the brittle regime (cataclastic flow) is modelled here in terms of Mohr-Coulomb behaviour in which all three of the parameters cohesion, friction angle and dilation angle follow hardening (or softening) evolution laws with both plastic straining and increases in confining pressure. The physical basis for such behaviour is provided by a sequence of uniaxial shortening experiments performed by Edmond and Paterson (1972) at confining pressures up to 800 MPa on a variety of materials including Gosford sandstone and Carrara marble. These triaxial compression experiments are important for the large range of confining pressures covered, and for the careful recording of data during deformation, particularly volume change of the specimens. Both materials are pressure-sensitive and dilatant. It is therefore possible to derive from these experiments a set of material parameters which allow a preliminary description of the deformation behaviour in terms of a non-associated, Mohr-Coulomb constitutive model, thus providing the first constitutive modelling of geological materials in the brittle-ductile regime. These parameters are used as input to a finite difference, numerical code (FLAC) with the aim of investigating how closely this numerical model simulates real material behaviour upon breakdown of homogeneous deformation. The mechanical and macrostructural behaviour exhibited by the numerical model is in close agreement with the physical results in that the stress-strain curves are duplicated together with localization behaviour. The results of the modelling illustrate how the strength of the upper-crust may be described by two different but still pressure-dependent models: the linear shear stress/normal stress relationship of Amontons (that is, Byerlee's Law), and a non-linear, Mohr-Coulomb constitutive model. Both include parameters of friction and both describe brittle deformation behaviour. Consideration of the non

  15. Pressure-Sensitive Paint Applied to Ice Accretions

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy J.

    1999-01-01

    Aircraft icing occurs when a plane flies through a cloud of supercooled water droplets. When the droplets impinge on aircraft components, ice starts to form and accumulate. This accumulation of ice severely increases the drag and lift of the aircraft, and can ultimately lead to catastrophic failures and even loss of life. Knowledge of the air pressures on the surfaces of ice and models in wind tunnels allows researchers to better predict the effects that different icing conditions will have on the performance of real aircraft. The use of pressure-sensitive paint (PSP) has provided valuable information on similar problems in conventional wind tunnel testing. In NASA Lewis Research Center Icing Research Tunnel, Lewis researchers recently demonstrated the world s first application of PSP on actual ice formed on a wind tunnel model. This proof-of-concept test showed that a new paint formulation developed under a grant by the University of Washington adheres to both the ice shapes and cold aluminum models, provides a uniform coating that preserves the detailed ice shape structure, and responds to simulated pressure changes.

  16. Development of a directional sensitive pressure and shear sensor

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Chih; Dee, Jeffrey; Ledoux, William; Sangeorzan, Bruce; Reinhall, Per G.

    2002-06-01

    Diabetes mellitus is a disease that impacts the lives of millions of people around the world. Lower limb complications associated with diabetes include the development of plantar ulcers that can lead to infection and subsequent amputation. Shear stress is thought to be a major contributing factor to ulcer development, but due in part to technical difficulties with transducing shear stress, there is no widely used shear measurement sensor. As such, we are currently developing a directionally sensitive pressure/shear sensor based on fiber optic technology. The pressure/shear sensor consists of an array of optical fibers lying in perpendicular rows and columns separated by elastomeric pads. A map of pressure and shear stress is constructed based on observed macro bending through the intensity attenuation from the physical deformation of two adjacent perpendicular fibers. The sensor has been shown to have low noise and responded linearly to applied loads. The smallest detectable force on each sensor element based on the current setup is ~0.1 lbs. (0.4N). The smallest area we have resolved in our mesh sensor is currently ~1 cm2.

  17. Evaluation of a new miniature pressure-sensitive radio transmitter

    USGS Publications Warehouse

    Beeman, J.W.; Haner, P.V.; Maule, A.G.

    1998-01-01

    A miniature pressure-sensitive radio transmitter (tag) was evaluated and field tested as a tool for determining the depths of juvenile salmonids. The tag had an effective radiated power of −19.7 decibels (1 mW reference), dimensions of 23 mm × 7 mm, and a weight of 2.2 g in air. The pulse rate of the tag increased with pressure, resulting in an expected tag life of approximately 11 d at the water surface and 7.5 d at 10.5 m. The tags were accurate to within 16 mm with 95% of observations within ±0.32 m of the true depth. The resolution of the tags was 0.2 m. Errors in indicated depth resulting from differences between the calibration and operating temperatures were minimized by means of a correction factor. Tags surgically implanted in juvenile steelhead Oncorhynchus mykiss indicated a depth 0.2 m less than the same tags in water. This difference was not affected by pressure or temperature and was rectified by adjusting data from tags in fish. A test tag in a Columbia River reservoir was detected from distances of 1,133 m at a depth of 2 m and 148 m at a depth of 14 m. Results ind

  18. The Hypersonic Lego: Getting started with Pressure Sensitive Paint

    NASA Astrophysics Data System (ADS)

    Munday, David; Fletcher, Doug

    2003-11-01

    Pressure Sensitive Paints (PSP) allow collection of surface pressure data simultaneously at a large number of points without the complexity of manufacturing a model with multiple taps, lines and transducers. The project reported here was to implement PSP in the von Karman Institute's (VKI's) Mach 6 hypersonic wind tunnel (H3). The goal was to demonstrate PSP on a simple geometry. The geometry employed is a blunt-faced obstruction (a LEGO) mounted on a flat plate in such a way as to create a bow shock impinging on the plate. This generates a large pressure range on a simple flat geometry. This presentation concentrates on the practical problems with the setup of PSP which are not often addressed in the existing literature and conveys the solutions employed at VKI. Subtler points having to do with optical setup and with post-processing of data have a pronounced effect on the strength and resolution of measurement and on signal to noise ratio. This paper is intended as a brief guide for others who wish to get started with PSP and to get a simple geometry running in their own facility on a base-line case.

  19. Degradation of adhesion molecules of G361 melanoma cells by a non-thermal atmospheric pressure microplasma

    NASA Astrophysics Data System (ADS)

    Lee, H. J.; Shon, C. H.; Kim, Y. S.; Kim, S.; Kim, G. C.; Kong, M. G.

    2009-11-01

    Increased expression of integrins and focal adhesion kinase (FAK) is important for the survival, growth and metastasis of melanoma cells. Based on this well-established observation in oncology, we propose to use degradation of integrin and FAK proteins as a potential strategy for melanoma cancer therapy. A low-temperature radio-frequency atmospheric microplasma jet is used to study their effects on the adhesion molecules of G361 melanoma cells. Microplasma treatment is shown to (1) cause significant cell detachment from the bottom of microtiter plates coated with collagen, (2) induce the death of human melanoma cells, (3) inhibit the expression of integrin α2, integrin α4 and FAK on the cell surface and finally (4) change well-stretched actin filaments to a diffuse pattern. These results suggest that cold atmospheric pressure plasmas can strongly inhibit the adhesion of melanoma cells by reducing the activities of adhesion proteins such as integrins and FAK, key biomolecules that are known to be important in malignant transformation and acquisition of metastatic phenotypes.

  20. Anomaly of sensitivity to pressure of side-hole HB optical fiber

    NASA Astrophysics Data System (ADS)

    Wojcik, Jan; Mergo, Pawel; Makara, Mariusz

    1999-04-01

    The birefringence of common types of optical fibers monotonically depends on temperature and pressure. Birefringence of some types of the side-hole (SH) optical fiber change sign of pressure sensitivity with change of pressure and temperature. This paper theoretically describes these phenomena. It is a supplement to previously described method of calculation of pressure and temperature sensitivity of SH optical fiber.

  1. Effects of antioxidant supplementation on insulin sensitivity, endothelial adhesion molecules, and oxidative stress in normal-weight and overweight young adults.

    PubMed

    Vincent, Heather K; Bourguignon, Cheryl M; Weltman, Arthur L; Vincent, Kevin R; Barrett, Eugene; Innes, Karen E; Taylor, Ann G

    2009-02-01

    The objective of the study was to determine whether short-term antioxidant (AOX) supplementation affects insulin sensitivity, endothelial adhesion molecule levels, and oxidative stress in overweight young adults. A randomized, double-blind, controlled study tested the effects of AOXs on measures of insulin sensitivity (homeostasis model assessment [HOMA]) and quantitative insulin sensitivity check index), endothelial adhesion molecules (soluble intercellular adhesion molecule-1, vascular adhesion molecule, and endothelial-leukocyte adhesion molecule-1), adiponectin, and oxidative stress (lipid hydroperoxides) in overweight and normal-weight individuals (N = 48, 18-30 years). Participants received either AOX (vitamin E, 800 IU; vitamin C, 500 mg; beta-carotene, 10 mg) or placebo for 8 weeks. The HOMA values were initially higher in the overweight subjects and were lowered with AOX by week 8 (15% reduction, P = .02). Adiponectin increased in both AOX groups. Soluble intercellular adhesion molecule-1 and endothelial-leukocyte adhesion molecule-1 decreased in overweight AOX-treated groups by 6% and 13%, respectively (P < .05). Plasma lipid hydroperoxides were reduced by 0.31 and 0.70 nmol/mL in the normal-weight and overweight AOX-treated groups, respectively, by week 8 (P < .05). Antioxidant supplementation moderately lowers HOMA and endothelial adhesion molecule levels in overweight young adults. A potential mechanism to explain this finding is the reduction in oxidative stress by AOX. Long-term studies are needed to determine whether AOXs are effective in suppressing diabetes or vascular activation over time. PMID:19154960

  2. An in vitro comparison of adhesive techniques and rotary instrumentation on shear bond strength of nanocomposite with simulated pulpal pressure

    PubMed Central

    Hegde, Jayshree; Sravanthi, Y

    2011-01-01

    Aim: The aim of this study is to evaluate the shear bond strength of composite to tooth using different adhesive techniques and rotary instruments under simulated pulpal pressure. Materials and Methods: Sixty extracted human molars were randomly divided into two groups of 30 samples each (group I and II), according to the adhesive technique followed (i.e. total etch and self etch groups). Each group was further divided into two sub-groups (Sub-groups A and B) of 15 samples each according to the cutting instrument (diamond abrasive or carbide burs) used. Class II cavities were made with diamond abrasive or carbide burs, and restored with nano-composite under positive intra-pulpal pressure. Shear bond strength of the specimens were recorded simultaneously. Results: After statistical evaluation using two-way ANOVA and t-test, the mean shear bond strength values of the groups are as follows: Group IA- 4.69 MPa, Group IB-6.15 MPa, Group IIA-4.3 MPa, and Group IIB-6.24 MPa. It was seen that group IIB showed highest bond strength followed by group IB. Group II A showed the least bond strength. Conclusions: Within the limitations of the study, diamond abrasive gave better bond strength than carbide bur with both the adhesive techniques. PMID:22025823

  3. A versatile pH sensitive chondroitin sulfate-PEG tissue adhesive and hydrogel.

    PubMed

    Strehin, Iossif; Nahas, Zayna; Arora, Karun; Nguyen, Thao; Elisseeff, Jennifer

    2010-04-01

    We developed a chondroitin sulfate-polyethylene glycol (CS-PEG) adhesive hydrogel with numerous potential biomedical applications. The carboxyl groups on chondroitin sulfate (CS) chains were functionalized with N-hydroxysuccinimide (NHS) to yield chondroitin sulfate succinimidyl succinate (CS-NHS). Following purification, the CS-NHS molecule can react with primary amines to form amide bonds. Hence, using six arm polyethylene glycol amine PEG-(NH2)6 as a crosslinker we formed a hydrogel which was covalently bound to proteins in tissue via amide bonds. By varying the initial pH of the precursor solutions, the hydrogel stiffness, swelling properties, and kinetics of gelation could be controlled. The sealing/adhesive strength could also be modified by varying the damping and storage modulus properties of the material. The adhesive strength of the material with cartilage tissue was shown to be ten times higher than that of fibrin glue. Cells encapsulated or in direct contact with the material remained viable and metabolically active. Furthermore, CS-PEG material produced minimal inflammatory response when implanted subcutaneously in a rat model and enzymatic degradation was demonstrated in vitro. This work establishes an adhesive hydrogel derived from biological and synthetic components with potential application in wound healing and regenerative medicine. PMID:20047758

  4. Babesia bovis expresses a neutralization-sensitive antigen that contains a microneme adhesive repeat (MAR) domain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A gene coding for a protein with sequence similarity to the Toxoplasma gondii micronemal 1 (MIC1) protein that contains a copy of a domain described as a sialic acid-binding micronemal adhesive repeat was identified in the Babesia bovis genome. The single copy gene, located in chromosome 3, contains...

  5. Soluble fms-like tyrosine kinase-1 and endothelial adhesion molecules (intercellular cell adhesion molecule-1 and vascular cell adhesion molecule-1) as predictive markers for blood pressure reduction after renal sympathetic denervation.

    PubMed

    Dörr, Oliver; Liebetrau, Christoph; Möllmann, Helge; Gaede, Luise; Troidl, Christian; Rixe, Johannes; Hamm, Christian; Nef, Holger

    2014-05-01

    Renal sympathetic denervation (RSD) is a treatment option for patients with resistant arterial hypertension, but in some patients it is not successful. Predictive parameters on the success of RSD remain unknown. The angiogenic factors soluble fms-like tyrosine kinase-1 (sFLT-1), intercellular cell adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) are known to be associated with endothelial dysfunction, vascular remodeling, and hypertension. We evaluated whether sFLT-1, ICAM-1, and VCAM-1 are predictive markers for blood pressure reduction after RSD. Consecutive patients (n=55) undergoing renal denervation were included. Venous serum samples for measurement of sFlt-1, ICAM-1, and VCAM-1 were collected before and 6 months after RSD. A therapeutic response was defined as an office systolic blood pressure reduction of >10 mm Hg 6 months after RSD. A significant mean office systolic blood pressure reduction of 31.2 mm Hg was observed in 46 patients 6 months after RSD. Nine patients were classified as nonresponders, with a mean systolic blood pressure reduction of 4.6 mm Hg. At baseline, sFLT-1 levels were significantly higher in responders than in nonresponders (P<0.001) as were ICAM-1 (P<0.001) and VCAM-1 levels (P<0.01). The areas under the curve for sFLT-1, ICAM-1, and VCAM-1 were 0.82 (interquartile range, 0.718-0.921; P<0.001), 0.754 (0.654-0.854; P<0.001), and 0.684 (0.564-804; P=0.01), respectively, demonstrating prediction of an RSD response. Responders showed significantly higher serum levels of sFLT-1, ICAM-1, and VCAM-1 at baseline compared with nonresponders. Thus, this study identified for the first time potential biomarkers with a predictive value indicating a responder or nonresponder before renal denervation. PMID:24470464

  6. Point pressure sensitivity in early stage Parkinson's disease.

    PubMed

    Doty, Richard L; Gandhi, Shifa S; Osman, Allen; Hurtig, Howard I; Pawasarat, Ian; Beals, Evan; Chung, Inna; Dubroff, Jacob; Newberg, Andrew; Ying, Gui-Shang; Leon-Sarmiento, Fidias E

    2015-01-01

    A number of sensory changes occur in the earliest stages of Parkinson's disease (PD), some of which precede the expression of the classic motor phenotype by years (e.g., olfactory dysfunction). Whether point pressure sensitivity (PPS), a cutaneous measure of light touch mediated by myelinated Aβ fibers, is altered in early PD is not clear. Prior studies on this point are contradictory and are based on non-forced-choice threshold tests that confound the sensitivity measure with the response criterion. While α-synuclein pathology, a defining feature of PD, is present in the skin of PD patients, it is restricted to unmyelinated nerve fibers, suggesting PPS may be spared in this disease. We determined PPS thresholds using a state-of-the-art forced-choice staircase threshold test paradigm in 29 early stage PD patients and 29 matched controls at 11 body sites: the center of the forehead and the left and right forearms, index fingers, palms, medial soles of the feet, and plantar halluces. The patients were tested, in counterbalanced sessions, both on and off dopamine-related medications (DRMs). PPS was not influenced by PD and did not correlate with DRM l-DOPA equivalents, scores on the Unified Parkinson's Disease Rating Scale, side of the major motor disturbances, or SPECT imaging of the striatal dopamine transporter, as measured by technetium-99m TRODAT. However, PPS thresholds were lower on the left than on the right side of the body (p=0.008) and on the upper extremities relative to the toes and feet (ps<0.0001). Positive correlations were evident among the thresholds obtained across all body sectors, even though disparate regions of the body differed in terms of absolute sensitivity. This study indicates that PPS is not influenced in early stage PD regardless of whether patients are on or off DRMs. PMID:25447476

  7. Pressurized thermal shock probabilistic fracture mechanics sensitivity analysis for Yankee Rowe reactor pressure vessel

    SciTech Connect

    Dickson, T.L.; Cheverton, R.D.; Bryson, J.W.; Bass, B.R.; Shum, D.K.M.; Keeney, J.A.

    1993-08-01

    The Nuclear Regulatory Commission (NRC) requested Oak Ridge National Laboratory (ORNL) to perform a pressurized-thermal-shock (PTS) probabilistic fracture mechanics (PFM) sensitivity analysis for the Yankee Rowe reactor pressure vessel, for the fluences corresponding to the end of operating cycle 22, using a specific small-break-loss- of-coolant transient as the loading condition. Regions of the vessel with distinguishing features were to be treated individually -- upper axial weld, lower axial weld, circumferential weld, upper plate spot welds, upper plate regions between the spot welds, lower plate spot welds, and the lower plate regions between the spot welds. The fracture analysis methods used in the analysis of through-clad surface flaws were those contained in the established OCA-P computer code, which was developed during the Integrated Pressurized Thermal Shock (IPTS) Program. The NRC request specified that the OCA-P code be enhanced for this study to also calculate the conditional probabilities of failure for subclad flaws and embedded flaws. The results of this sensitivity analysis provide the NRC with (1) data that could be used to assess the relative influence of a number of key input parameters in the Yankee Rowe PTS analysis and (2) data that can be used for readily determining the probability of vessel failure once a more accurate indication of vessel embrittlement becomes available. This report is designated as HSST report No. 117.

  8. Pressure sensitive paint systems for pressure distribution measurements in wind tunnels and turbomachines

    NASA Astrophysics Data System (ADS)

    Engler, R. H.; Klein, Chr; Trinks, O.

    2000-07-01

    We have used the pressure-sensitive paint (PSP) intensity and lifetime methods for basic research and PSP measurements in wind tunnels and turbomachines, to investigate and understand the qualitative and quantitative aerodynamic measurements mainly in transonic flow. We performed a number of investigations in different speed ranges from transonic to low-speed flow and compared them with conventional techniques like pressure taps and light sheets. The influence of errors was checked and a comparison with numerical methods performed. Various models were investigated, from the basic configuration of a double-delta-wing up to a complex Airbus A340 half model and oscillating turbine blades. Finally, two excellent PSP systems are now available to perform precise measurements and support the theory using these techniques.

  9. Adhesive-backed terminal board eliminates mounting screws

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Low-profile terminal board is used in dense electronic circuits where mounting and working space is limited. The board has a thin layer of pressure-sensitive adhesive backing which eliminates the need for mounting screws.

  10. Measuring Global Surface Pressures on a Circulation Control Concept Using Pressure Sensitive Paint

    NASA Technical Reports Server (NTRS)

    Watkins, Anthony N.; Lipford, William E.; Leighty, Bradley D.; Goodman, Kyle Z.; Goad, William K.

    2012-01-01

    This report will present the results obtained from the Pressure Sensitive Paint (PSP) technique on a circulation control concept model. This test was conducted at the National Transonic Facility (NTF) at the NASA Langley Research Center. PSP was collected on the upper wing surface while the facility was operating in cryogenic mode at 227 K (-50 oF). The test envelope for the PSP portion included Mach numbers from 0.7 to 0.8 with angle of attack varying between 0 and 8 degrees and a total pressure of approximately 168 kPa (24.4 psi), resulting in a chord Reynolds number of approximately 15 million. While the PSP results did exhibit high levels of noise in certain conditions (where the oxygen content of the flow was very small), some conditions provided good correlation between the PSP and pressure taps, showing the ability of the PSP technique. This work also served as a risk reduction opportunity for future testing in cryogenic conditions at the NTF.

  11. Oxalic acid under adhesive restorations as a means to reduce dentin sensitivity: a four-month clinical trial.

    PubMed

    Barrientos, Claudia; Xaus, Gloria; Leighton, Catherine; Martin, Javier; Gordan, Valeria V; Moncada, Gustavo

    2011-01-01

    The aim of this double-blind randomized controlled clinical trial was to evaluate the reduction of dentin sensitivity using an oxalate-based compound, placed under adhesive restorations, during a four-month period. One hundred three preoperatively sensitive teeth, on 36 patients aged 25-66 years (mean, 40.3±7), were included in the study. Group A (experimental) was treated with oxalic acid (BisBlock) before resin-based composite (RBC) restorations (n=52), and group B (control) was treated with distilled water before RBC restorations (n=51). The first tooth in each patient was randomly assigned to group A, and the second tooth received group B. Clinical evaluation as made by a thermal/evaporation test with an air syringe and measurement by visual analog scale (VAS) at baseline and four months after treatment. The results showed sensitivity reduction during the evaluation period (expressed in VAS values): group A, 7.6 to 0.8; group B, 7.3 to 2.6. We concluded from this study that both treatments reduced dentin sensitivity during the evaluation period, with group A showing significantly less dentin sensitivity after four months (p<0.05). PMID:21777095

  12. Current pharmaceutical design on adhesive based transdermal drug delivery systems.

    PubMed

    Ghosh, Animesh; Banerjee, Subham; Kaity, Santanu; Wong, Tin W

    2015-01-01

    Drug-in-adhesive transdermal drug delivery matrix exploits intimate contact of the carrier with stratum corneum, the principal skin barrier to drug transport, to deliver the actives across the skin and into the systemic circulation. The main application challenges of drug-in-adhesive matrix lie in the physicochemical properties of skin varying with age, gender, ethnicity, health and environmental condition of patients. This in turn poses difficulty to design a universal formulation to meet the intended adhesiveness, drug release and drug permeation performances. This review focuses on pressure-sensitive adhesives, and their adhesiveness and drug release/permeation modulation mechanisms as a function of adhesive molecular structure and formulation attributes. It discusses approaches to modulate adhesive tackiness, strength, elasticity, hydrophilicity, molecular suspension capability and swelling capacity, which contribute to the net effect of adhesive on skin bonding, drug release and drug permeation. PMID:25925119

  13. Modeling flow in a pressure-sensitive, heterogeneous medium

    SciTech Connect

    Vasco, Donald W.; Minkoff, Susan E.

    2009-06-01

    Using an asymptotic methodology, including an expansion in inverse powers of {radical}{omega}, where {omega} is the frequency, we derive a solution for flow in a medium with pressure dependent properties. The solution is valid for a heterogeneous medium with smoothly varying properties. That is, the scale length of the heterogeneity must be significantly larger then the scale length over which the pressure increases from it initial value to its peak value. The resulting asymptotic expression is similar in form to the solution for pressure in a medium in which the flow properties are not functions of pressure. Both the expression for pseudo-phase, which is related to the 'travel time' of the transient pressure disturbance, and the expression for pressure amplitude contain modifications due to the pressure dependence of the medium. We apply the method to synthetic and observed pressure variations in a deforming medium. In the synthetic test we model one-dimensional propagation in a pressure-dependent medium. Comparisons with both an analytic self-similar solution and the results of a numerical simulation indicate general agreement. Furthermore, we are able to match pressure variations observed during a pulse test at the Coaraze Laboratory site in France.

  14. Design and Application of a High Sensitivity Piezoresistive Pressure Sensor for Low Pressure Conditions

    PubMed Central

    Yu, Huiyang; Huang, Jianqiu

    2015-01-01

    In this paper, a pressure sensor for low pressure detection (0.5 kPa–40 kPa) is proposed. In one structure (No. 1), the silicon membrane is partly etched to form a crossed beam on its top for stress concentration. An aluminum layer is also deposited as part of the beam. Four piezoresistors are fabricated. Two are located at the two ends of the beam. The other two are located at the membrane periphery. Four piezoresistors connect into a Wheatstone bridge. To demonstrate the stress concentrate effect of this structure, two other structures were designed and fabricated. One is a flat membrane structure (No. 2), the other is a structure with the aluminum beam, but without etched silicon (No. 3). The measurement results of these three structures show that the No.1 structure has the highest sensitivity, which is about 3.8 times that of the No. 2 structure and 2.7 times that of the No. 3 structure. They also show that the residual stress in the beam has some backside effect on the sensor performance. PMID:26371001

  15. Design and Application of a High Sensitivity Piezoresistive Pressure Sensor for Low Pressure Conditions.

    PubMed

    Yu, Huiyang; Huang, Jianqiu

    2015-01-01

    In this paper, a pressure sensor for low pressure detection (0.5 kPa-40 kPa) is proposed. In one structure (No. 1), the silicon membrane is partly etched to form a crossed beam on its top for stress concentration. An aluminum layer is also deposited as part of the beam. Four piezoresistors are fabricated. Two are located at the two ends of the beam. The other two are located at the membrane periphery. Four piezoresistors connect into a Wheatstone bridge. To demonstrate the stress concentrate effect of this structure, two other structures were designed and fabricated. One is a flat membrane structure (No. 2), the other is a structure with the aluminum beam, but without etched silicon (No. 3). The measurement results of these three structures show that the No.1 structure has the highest sensitivity, which is about 3.8 times that of the No. 2 structure and 2.7 times that of the No. 3 structure. They also show that the residual stress in the beam has some backside effect on the sensor performance. PMID:26371001

  16. Enhancement of carbon-steel peel adhesion to rubber blend using atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Kršková, Jana; Skácelová, Dana; Kováčik, Dušan; Ráhel', Jozef; Pret'o, Jozef; Černák, Mirko

    2016-08-01

    The surface of carbon-steel plates was modified by non-equilibrium plasma of diffuse coplanar surface barrier discharge (DCSBD) in order to improve the adhesive properties to the NR (natural rubber) green rubber compound. The effect of different treatment times as well as different input power and frequency of supplied high voltage was investigated. The samples were characterized using contact angle and surface free energy measurement, measurement of adhesive properties, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Surface chemical composition was studied by energy-dispersive X-ray spectroscopy (EDX). Significant increase in wettability was observed even after 2 s of plasma exposure. The surface modification was confirmed also by peel test, where the best results were obtained for 6 s of plasma treatment. In addition the ageing effect was studied to investigate the durability of modification, which is crucial for the industrial applications. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  17. Mutation of Drosophila Focal Adhesion Kinase Induces Bang-Sensitive Behavior and Disrupts Glial Function, Axonal Conduction and Synaptic Transmission

    PubMed Central

    Ueda, Atsushi; Grabbe, Caroline; Lee, Jihye; Lee, Jisue; Palmer, Ruth H.; Wu, Chun-Fang

    2009-01-01

    The role of the conserved Focal Adhesion Kinase (FAK) family of protein tyrosine kinases (PTKs) in the development and physiological functions of the CNS has long been an area of interest among neuroscientists. In this report, we observe that Drosophila mutants lacking Fak56 exhibit a decreased life span, accompanied by a bang-sensitive phenotype, which is characterised by sensitivity to mechanical and high-frequency electrical stimulation. Fak56 mutant animals display lower thresholds and higher rates of seizures in response to electroconvulsive stimuli, and direct measurements of action potential conduction in larval segmental nerves demonstrate a slowed propagation speed and failure during high-frequency nerve stimulation. In addition, neuromuscular junctions in Fak56 mutant animals display transmission blockade during high-frequency activity as a result of action potential failure. Endogenous Fak56 protein is abundant in glial cells ensheathing the axon bundles, and structural alterations of segmental nerve bundles can be observed in mutants. Manipulation of Fak56 function specifically in glial cells also disrupts action potential conduction and neurotransmission, suggesting a glial component in the Fak56 bang-sensitive phenotype. Furthermore, we show that increased intracellular calcium levels result in the dephosphorylation of endogenous Fak56 protein in Drosophila cell lines, in parallel with our observations of highly variable synaptic potentials at a higher Ca2+ level in Fak56 mutant larvae. Together these findings suggest that modulation of Fak56 function is important for action potential propagation and Ca2+-regulated neuromuscular transmission in vivo. PMID:18540882

  18. 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

    2016-05-01

    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. PMID:27046671

  19. CD44 sensitivity of platelet activation, membrane scrambling and adhesion under high arterial shear rates.

    PubMed

    Liu, Guilai; Liu, Guoxing; Alzoubi, Kousi; Chatterjee, Madhumita; Walker, Britta; Münzer, Patrick; Luo, Dong; Umbach, Anja T; Elvira, Bernat; Chen, Hong; Voelkl, Jakob; Föller, Michael; Mak, Tak W; Borst, Oliver; Gawaz, Meinrad; Lang, Florian

    2016-01-01

    CD44 is required for signalling of macrophage migration inhibitory factor (MIF), an anti-apoptotic pro-inflammatory cytokine. MIF is expressed and released from blood platelets, key players in the orchestration of occlusive vascular disease. Nothing is known about a role of CD44 in the regulation of platelet function. The present study thus explored whether CD44 modifies degranulation (P-selectin exposure), integrin activation, caspase activity, phosphatidylserine exposure on the platelet surface, platelet volume, Orai1 protein abundance and cytosolic Ca(2+)-activity ([Ca2+]i). Platelets from mice lacking CD44 (cd44(-/-)) were compared to platelets from corresponding wild-type mice (cd44(+/+)). In resting platelets, P-selectin abundance, α(IIb)β3 integrin activation, caspase-3 activity and phosphatidylserine exposure were negligible in both genotypes and Orai1 protein abundance, [Ca2+]i, and volume were similar in cd44(-/-) and cd44(+/+) platelets. Platelet degranulation and α(IIb)β3 integrin activation were significantly increased by thrombin (0.02 U/ml), collagen related peptide (CRP, 2 µg/ml and Ca(2+)-store depletion with thapsigargin (1 µM), effects more pronounced in cd44(-/-) than in cd44(+/+) platelets. Thrombin (0.02 U/ml) increased platelet [Ca2+]i, caspase-3 activity, phosphatidylserine exposure and Orai1 surface abundance, effects again significantly stronger in cd44(-/-) than in cd44(+/+) platelets. Thrombin further decreased forward scatter in cd44(-/-) and cd44(+/+) platelets, an effect which tended to be again more pronounced in cd44(-/-) than in cd44(+/+) platelets. Platelet adhesion and in vitro thrombus formation under high arterial shear rates (1,700 s(-1)) were significantly augmented in cd44(-/-) mice. In conclusion, genetic deficiency of CD44 augments activation, apoptosis and pro-thrombotic potential of platelets. PMID:26355696

  20. Pressure and Temperature Sensitive Paint Measurements on Rotors

    NASA Technical Reports Server (NTRS)

    Sullivan, John

    1999-01-01

    Luminescent molecular probes imbedded in a polymer binder form a temperature or pressure paint. On excitation by light of the proper wavelength, the luminescence, which is quenched either thermally or by oxygen, is detected by a camera or photodetector. From the detected luminescent intensity, temperature and pressure can be determined. The basic photophysics, calibration, accuracy and time response of luminescent paints is described followed by applications in wind tunnels and in rotating machinery.

  1. Sensitivity, specificity, and predictive values of a forearm blood pressure measurement method in severe obesity.

    PubMed

    Leblanc, Marie-Ève; Cloutier, Lyne; Poirier, Paul

    2015-04-01

    For blood pressure assessment, it has been reported that forearm blood pressure measurement appears to be as valid as an upper-arm blood pressure measurement method in individuals with severe obesity when correlated to the intra-arterial method, considered as the gold standard. Sensitivity, specificity, and predictive values for the presence of systemic hypertension in 25 severely obese patients from 352 blood pressure measurements were calculated. The sensitivity (0.98) and the positive predictive value (0.93) for hypertension on forearm blood pressure measurements are excellent, indicating that the forearm approach is a promising alternative to systemic hypertension diagnosis in severe obesity. PMID:25757220

  2. Application of the pressure sensitive paint technique to steady and unsteady flow

    NASA Technical Reports Server (NTRS)

    Shimbo, Y.; Mehta, R.; Cantwell, B.

    1996-01-01

    Pressure sensitive paint is a newly-developed optical measurement technique with which one can get a continuous pressure distribution in much shorter time and lower cost than a conventional pressure tap measurement. However, most of the current pressure sensitive paint applications are restricted to steady pressure measurement at high speeds because of the small signal-to-noise ratio at low speed and a slow response to pressure changes. In the present study, three phases of work have been completed to extend the application of the pressure sensitive paint technique to low-speed testing and to investigate the applicability of the paint technique to unsteady flow. First the measurement system using a commercially available PtOEP/GP-197 pressure sensitive paint was established and applied to impinging jet measurements. An in-situ calibration using only five pressure tap data points was applied and the results showed good repeatability and good agreement with conventional pressure tap measurements on the whole painted area. The overall measurement accuracy in these experiments was found to be within 0.1 psi. The pressure sensitive paint technique was then applied to low-speed wind tunnel tests using a 60 deg delta wing model with leading edge blowing slots. The technical problems encountered in low-speed testing were resolved by using a high grade CCD camera and applying corrections to improve the measurement accuracy. Even at 35 m/s, the paint data not only agreed well with conventional pressure tap measurements but also clearly showed the suction region generated by the leading edge vortices. The vortex breakdown was also detected at alpha=30 deg. It was found that a pressure difference of 0.2 psi was required for a quantitative pressure measurement in this experiment and that temperature control or a parallel temperature measurement is necessary if thermal uniformity does not hold on the model. Finally, the pressure sensitive paint was applied to a periodically

  3. Application of the Polymer Based Pressure Sensitive Paint for Qualitative and Quantitative Flow Visualisation in a Transonic Flow

    NASA Astrophysics Data System (ADS)

    Lo, K. H.; Zare-Behtash, H.; Kontis, K.; Qin, N.

    Surface pressure measurement by Pressure Sensitive Paint (PSP) becomes an active area of research in the engineering industry. Conventional pressure measurement techniques require to incoporate pressure taps within the model.

  4. Printing transferable components using microstructured elastomeric surfaces with pressure modulated reversible adhesion

    DOEpatents

    Menard, Etienne; Rogers, John A.; Kim, Seok; Carlson, Andrew

    2016-08-09

    In a method of printing a transferable component, a stamp including an elastomeric post having three-dimensional relief features protruding from a surface thereof is pressed against a component on a donor substrate with a first pressure that is sufficient to mechanically deform the relief features and a region of the post between the relief features to contact the component over a first contact area. The stamp is retracted from the donor substrate such that the component is adhered to the stamp. The stamp including the component adhered thereto is pressed against a receiving substrate with a second pressure that is less than the first pressure to contact the component over a second contact area that is smaller than the first contact area. The stamp is then retracted from the receiving substrate to delaminate the component from the stamp and print the component onto the receiving substrate. Related apparatus and stamps are also discussed.

  5. Pressure sensitivity of adiabatic shear banding in metals

    NASA Astrophysics Data System (ADS)

    Hanina, E.; Rittel, D.; Rosenberg, Z.

    2007-01-01

    Adiabatic shear banding (ASB) is a dynamic failure mode characterized by large plastic strains in a narrow localized band. ASB occurs at high strain rates (ɛ˙⩾103s-1), under adiabatic conditions leading to a significant temperature rise inside the band [H. Tresca, Annales du Conservatoire des Arts et Métiers 4, (1879); Y. L. Bai and B. Dodd, Adiabatic Shear Localization-Occurrence, Theories, and Applications (Pergamon, Oxford, 1992); M. A. Meyers, Dynamic Behavior of Materials (Wiley, New York, 1994).; and J. J. Lewandowski and L. M. Greer, Nat. Mater. 5, 15 (2006)]. Large hydrostatic pressures are experienced in many dynamic applications involving ASB formation (e.g., ballistic penetration, impact, and machining). The relationship between hydrostatic pressure and ASB development remains an open question, although its importance has been often noted. This letter reports original experimental results indicating a linear relationship between the (normalized) dynamic deformation energy and the (normalized) hydrostatic pressure.

  6. Visualization of turbulent wedges under favorable pressure gradients using shear-sensitive and temperature-sensitive liquid crystals.

    PubMed

    Chong, Tze-Pei; Zhong, Shan; Hodson, Howard P

    2002-10-01

    Turbulent wedges induced by a three-dimensional surface roughness placed on a flat plate were studied using both shear sensitive and temperature sensitive liquid crystals, respectively denoted by SSLC and TSLC. The experiments were carried out at a free-stream velocity of 28 m/sec at three different favorable pressure gradients. The purpose of this investigation was to examine the spreading angles of the turbulent wedges, as indicated by their associated surface shear stresses and heat transfer characteristics, and to obtain more insight about the behavior of transitional momentum and thermal boundary layers when a streamwise pressure gradient exists. It was shown that under a zero pressure gradient the spreading angles indicated by the two types of liquid crystals are the same, but the difference increases as the level of the favorable pressure gradient increases. The result from the present study is important for modelling the transition of thermal boundary layers over gas turbine blades. PMID:12496003

  7. Variable high pressure processing sensitivities for GII human noroviruses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Human norovirus (HuNoV) is the leading cause of foodborne diseases worldwide. High pressure processing (HPP) is one of the most promising non-thermal technologies for decontamination of viral pathogens in foods. However, the survival of HuNoVs by HPP is poorly understood because these viruses cann...

  8. Impact sensitivity of materials in contact with liquid and gaseous oxygen at high pressure

    NASA Technical Reports Server (NTRS)

    Schwinghamer, R. J.

    1972-01-01

    As a result of the Apollo 13 incident, increased emphasis is being placed on materials compatibility in a high pressure GOX environment. It is known that in addition to impact sensitivity of materials, approximately adiabatic compression conditions can contrive to induce materials reactivity. Test runs at high pressure using the ABMA tester indicate the following: (1) The materials used in the tests showed an inverse relationship between thickness and impact sensitivity. (2) Several materials tested exhibited greater impact sensitivity in GOX than in LOX. (3) The impact sensitivity of the materials tested in GOX, at the pressures tested, showed enhanced impact sensitivity with higher pressure. (4) The rank ordering of the materials tested in LOX up to 1000 psia is the same as the rank ordering resulting from tests in LOX at 14.7 psia.

  9. Tongue adhesion in the horned frog Ceratophrys sp.

    NASA Astrophysics Data System (ADS)

    Kleinteich, Thomas; Gorb, Stanislav N.

    2014-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Jin, Kejia

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

  11. Polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Progar, D. J.; Bell, V. L.; Saintclair, T. L. (Inventor)

    1974-01-01

    A process of preparing aromatic polyamide-acids for use as adhesives is described. An equimolar quantity of an aromatic dianhydride is added to a stirred solution of an aromatic diamine in a water or alcohol-miscible ether solvent to obtain a viscous polymer solution. The polymeric-acid intermediate polymer does not become insoluble but directly forms a smooth viscous polymer solution. These polyamic-acid polymers are converted, by heating in the range of 200-300 C and with pressure, to form polyimides with excellent adhesive properties.

  12. Pressure Effects on the Temperature Sensitivity of Fiber Bragg Gratings

    NASA Technical Reports Server (NTRS)

    Wu, Meng-Chou

    2012-01-01

    A 3-dimensional physical model was developed to relate the wavelength shifts resulting from temperature changes of fiber Bragg gratings (FBGs) to the thermal expansion coefficients, Young s moduli of optical fibers, and thicknesses of coating polymers. Using this model the Bragg wavelength shifts were calculated and compared with the measured wavelength shifts of FBGs with various coating thickness for a finite temperature range. There was a discrepancy between the calculated and measured wavelength shifts. This was attributed to the refractive index change of the fiber core by the thermally induced radial pressure. To further investigate the pressure effects, a small diametric load was applied to a FBG and Bragg wavelength shifts were measured over a temperature range of 4.2 to 300K.

  13. Pressure-Sensitive System for Gas-Temperature Control

    NASA Technical Reports Server (NTRS)

    Cesaro, Richard S; Matz, Norman

    1948-01-01

    A thermodynamic relation is derived and simplified for use as a temperature-limiting control equation involving measurement of gas temperature before combustion and gas pressures before and after combustion. For critical flow in the turbine nozzles of gas-turbine engines, the control equation is further simplified to require only measurements upstream of the burner. Hypothetical control systems are discussed to illustrate application of the control equations.

  14. Acquisition of cell-adhesion capability of the surface of crosslinked albumin films irradiated with atmospheric-pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Shirafuji, Tatsuru; Iwamura, Mami; Taga, Ryosuke; Kashiwagi, Yukiyasu; Nakajima, Kota; Ogata, Yuji; Tanaka, Kenji; Tachibana, Akira; Tanabe, Toshizumi

    2016-07-01

    Crosslinked albumin films, to which L929 cells do not attach by nature, acquire the L929-cell-adhesion capability by irradiation of an atmospheric-pressure plasma jet (APPJ) of He gas. The number of attached cells was 2.6 × 104 cells/cm2 after the APPJ irradiation for 180 s, while conventional UV photolithography, which was performed in our previous work, required 2 h to obtain the same order of magnitude of the number of attached cells. The contact angle of samples decreased steeply from 105 to 38° in the first 10 s irradiation, but decreased quite gradually from 38 to 32° with increasing irradiation time from 10 to 180 s. In contrast to the nonlinear variation in the contact angles, the number of attached cells almost linearly increased from 4.5 × 103 to 2.6 × 104 cells/cm2 with increasing treatment time. X-ray photoelectron spectroscopy of the samples indicated that hydrophilic functional groups of C–C=O gradually formed with increasing APPJ irradiation time up to 180 s. These results suggest that the cell-adhesion capability of the crosslinked albumin films is not simply explained by the decrease in contact angle but also by the formation of oxidized functional groups on the surface. The effects of UV and vacuum UV light from APPJ were negligible, which indicates that the formation of oxidized functional groups on the surface is not caused by photon-assisted surface reactions but by reactions involving chemically active species supplied from APPJ.

  15. High-sensitivity Fabry-Perot interferometric pressure sensor based on a nanothick silver diaphragm.

    PubMed

    Xu, Feng; Ren, Dongxu; Shi, Xiaolong; Li, Can; Lu, Weiwei; Lu, Lu; Lu, Liang; Yu, Benli

    2012-01-15

    We present a fiber-optic extrinsic Fabry-Perot interferometer pressure sensor based on a nanothick silver diaphragm. The sensing diaphragm, with a thickness measured in a few hundreds of nanometers, is fabricated by the electroless plating method, which provides a simple fabrication process involving a high-quality diaphragm at a low cost. The sensor exhibits a relatively linear response within the pressure variation range of 0-50 kPa, with a high pressure sensitivity of 70.5 nm/kPa. This sensor is expected to have potential applications in the field of highly sensitive pressure sensors. PMID:22854444

  16. Amine Enrichment of Thin-Film Composite Membranes via Low Pressure Plasma Polymerization for Antimicrobial Adhesion.

    PubMed

    Reis, Rackel; Dumée, Ludovic F; He, Li; She, Fenghua; Orbell, John D; Winther-Jensen, Bjorn; Duke, Mikel C

    2015-07-15

    Thin-film composite membranes, primarily based on poly(amide) (PA) semipermeable materials, are nowadays the dominant technology used in pressure driven water desalination systems. Despite offering superior water permeation and salt selectivity, their surface properties, such as their charge and roughness, cannot be extensively tuned due to the intrinsic fabrication process of the membranes by interfacial polymerization. The alteration of these properties would lead to a better control of the materials surface zeta potential, which is critical to finely tune selectivity and enhance the membrane materials stability when exposed to complex industrial waste streams. Low pressure plasma was employed to introduce amine functionalities onto the PA surface of commercially available thin-film composite (TFC) membranes. Morphological changes after plasma polymerization were analyzed by SEM and AFM, and average surface roughness decreased by 29%. Amine enrichment provided isoelectric point changes from pH 3.7 to 5.2 for 5 to 15 min of plasma polymerization time. Synchrotron FTIR mappings of the amine-modified surface indicated the addition of a discrete 60 nm film to the PA layer. Furthermore, metal affinity was confirmed by the enhanced binding of silver to the modified surface, supported by an increased antimicrobial functionality with demonstrable elimination of E. coli growth. Essential salt rejection was shown minimally compromised for faster polymerization processes. Plasma polymerization is therefore a viable route to producing functional amine enriched thin-film composite PA membrane surfaces. PMID:26083007

  17. Reverse-micelle-induced porous pressure-sensitive rubber for wearable human-machine interfaces.

    PubMed

    Jung, Sungmook; Kim, Ji Hoon; Kim, Jaemin; Choi, Suji; Lee, Jongsu; Park, Inhyuk; Hyeon, Taeghwan; Kim, Dae-Hyeong

    2014-07-23

    A novel method to produce porous pressure-sensitive rubber is developed. For the controlled size distribution of embedded micropores, solution-based procedures using reverse micelles are adopted. The piezosensitivity of the pressure sensitive rubber is significantly increased by introducing micropores. Using this method, wearable human-machine interfaces are fabricated, which can be applied to the remote control of a robot. PMID:24827418

  18. Reinforcing element and demand sensitive pressure intensifier for sealing a well casing

    SciTech Connect

    Wambaugh, J. O.

    1985-10-08

    A reinforcing element for an elastomeric sealing element for use within a well casing and passable through production tubing is formed of two metallic plate members having a plurality of radially extending projections, and the radially extending projections are bent and joined to one another to allow the reinforcing element to be passed through production tubing. A demand sensitive pressure intensifier for use with a hydraulic fluid pump and passable through production tubing has a means for compressing hydraulic fluid to a pressure which exceeds the maximum output pressure of the pump, and the compression means is selectively actuated when the output pressure of the pump reaches a predetermined pressure value.

  19. Low-Speed Flow Studies Using the Pressure Sensitive Paint Technique

    NASA Technical Reports Server (NTRS)

    Brown, O. C.; Mehta, R. D.; Cantwell, B. J.

    1998-01-01

    Optical pressure measurements have been made on a NACA 0012 airfoil coated with Pressure Sensitive Paint (PSP) at very low flow speeds (less than 50 m/s). Angle of attack was limited to 5 deg. for most measurements. Effects of temperature gradients and mis-registration errors on PSP response have been established and minimized. By reducing measurement error caused by these effects. PSP sensitivity has been enhanced. Acceptable aerodynamic data at flow speeds down to 20 m/s have been obtained and valid pressure paint response was observed down to 10 m/s. Measurement errors (in terms of pressure and pressure coefficient) using PSP with pressure taps as a reference are provided for the range of flow speeds from 50 m/s to 10 m/s.

  20. Ultrafast Time Response Pressure-Sensitive Paint for Unsteady Shock-Wave Research

    NASA Astrophysics Data System (ADS)

    Numata, Daiju; Asai, Keisuke

    Pressure-Sensitive Paint (PSP) is an optical pressure measurement technique widely used in aerodynamic experiments, and has been applied to unsteady shock-wave phenomena [1, 2]. However, one of the largest problems to apply PSP to high-speed and unsteady phenomena is the response time of PSP.

  1. A highly sensitive pressure sensor using conductive composite elastomers with wavy structures

    NASA Astrophysics Data System (ADS)

    Sun, Rujie; Zhang, Xiao-Chong; Rossiter, Jonathan; Scarpa, Fabrizio

    2016-05-01

    Flexible pressure sensors are crucial components for the next generation wearable devices to monitor human physiological conditions. In this paper, we present a novel resistive pressure sensor based on hybrid composites made from carbon nanotube (CNT) for the conductive coating layer and polydimethylsiloxane (PDMS) elastomers as the substrate. The high sensitivity of these sensors is attributed to the change of contact resistance caused by the variation of the contact areas between the wavy film and the electrodes. Porous electrodes were designed to increase the roughness of the interfaces, thus further enhancing the pressure sensitivity. The developed device was verified through a series of tests, and the sensor exhibited a high sensitivity of 2.05 kPa-1 under a low pressure of 35.6 Pa.

  2. Effect of surfactants on pressure-sensitivity of CNT filled cement mortar composites

    NASA Astrophysics Data System (ADS)

    Han, Baoguo; Yu, Xun

    2014-11-01

    Sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (NaDDBS) were used as surfactants to disperse multi-walled carbon nanotubes (MWNT) in cement mortar and fabricate pressure-sensitive carbon nanotubes filled cement mortar composites. The pressure-sensitivity of cement mortar composites with different concentrations of MWNT and different surfactants was explored under repeated loading and impulsive loading, respectively. Experimental results indicate that the response of the electrical resistance of composites with NaDDBS to external force is more stable and sensitive than that of composites with SDS. Therefore, NaDDBS has higher efficiency than SDS for the dispersion of MWNT in cement mortar, and it is an effective surfactant for fabricating MWNT filled cement mortar composites with superior pressure-sensitivity.

  3. Effect of Temperature-Sensitive Poloxamer Solution/Gel Material on Pericardial Adhesion Prevention: Supine Rabbit Model Study Mimicking Cardiac Surgery

    PubMed Central

    Kang, Hyun; Chung, Yoon Sang; Kim, Sang Wook; Choi, Geun Joo; Kim, Beom Gyu; Park, Suk Won; Seok, Ju Won; Hong, Joonhwa

    2015-01-01

    Objective We investigated the mobility of a temperature-sensitive poloxamer/Alginate/CaCl2 mixture (PACM) in relation to gravity and cardiac motion and the efficacy of PACM on the prevention of pericardial adhesion in a supine rabbit model. Methods A total of 50 rabbits were randomly divided into two groups according to materials applied after epicardial abrasion: PACM and dye mixture (group PD; n = 25) and saline as the control group (group CO; n = 25). In group PD, rabbits were maintained in a supine position with appropriate sedation, and location of mixture of PACM and dye was assessed by CT scan at the immediate postoperative period and 12 hours after surgery. The grade of adhesions was evaluated macroscopically and microscopically two weeks after surgery. Results In group PD, enhancement was localized in the anterior pericardial space, where PACM and dye mixture was applied, on immediate post-surgical CT scans. However, the volume of the enhancement was significantly decreased at the anterior pericardial space 12 hours later (P < .001). Two weeks after surgery, group PD had significantly lower macroscopic adhesion score (P = .002) and fibrosis score (P = .018) than did group CO. Inflammation score and expression of anti-macrophage antibody in group PD were lower than those in group CO, although the differences were not significant. Conclusions In a supine rabbit model study, the anti-adhesion effect was maintained at the area of PACM application, although PACM shifted with gravity and heart motion. For more potent pericardial adhesion prevention, further research and development on the maintenance of anti-adhesion material position are required. PMID:26580394

  4. Graphene ``microdrums'' on a freestanding perforated thin membrane for high sensitivity MEMS pressure sensors

    NASA Astrophysics Data System (ADS)

    Wang, Qiugu; Hong, Wei; Dong, Liang

    2016-03-01

    We present a microelectromechanical system (MEMS) graphene-based pressure sensor realized by transferring a large area, few-layered graphene on a suspended silicon nitride thin membrane perforated by a periodic array of micro-through-holes. Each through-hole is covered by a circular drum-like graphene layer, namely a graphene ``microdrum''. The uniqueness of the sensor design is the fact that introducing the through-hole arrays into the supporting nitride membrane allows generating an increased strain in the graphene membrane over the through-hole array by local deformations of the holes under an applied differential pressure. Further reasons contributing to the increased strain in the devised sensitive membrane include larger deflection of the membrane than that of its imperforated counterpart membrane, and direct bulging of the graphene microdrum under an applied pressure. Electromechanical measurements show a gauge factor of 4.4 for the graphene membrane and a sensitivity of 2.8 × 10-5 mbar-1 for the pressure sensor with a good linearity over a wide pressure range. The present sensor outperforms most existing MEMS-based small footprint pressure sensors using graphene, silicon, and carbon nanotubes as sensitive materials, due to the high sensitivity.

  5. Graphene "microdrums" on a freestanding perforated thin membrane for high sensitivity MEMS pressure sensors.

    PubMed

    Wang, Qiugu; Hong, Wei; Dong, Liang

    2016-04-14

    We present a microelectromechanical system (MEMS) graphene-based pressure sensor realized by transferring a large area, few-layered graphene on a suspended silicon nitride thin membrane perforated by a periodic array of micro-through-holes. Each through-hole is covered by a circular drum-like graphene layer, namely a graphene "microdrum". The uniqueness of the sensor design is the fact that introducing the through-hole arrays into the supporting nitride membrane allows generating an increased strain in the graphene membrane over the through-hole array by local deformations of the holes under an applied differential pressure. Further reasons contributing to the increased strain in the devised sensitive membrane include larger deflection of the membrane than that of its imperforated counterpart membrane, and direct bulging of the graphene microdrum under an applied pressure. Electromechanical measurements show a gauge factor of 4.4 for the graphene membrane and a sensitivity of 2.8 × 10(-5) mbar(-1) for the pressure sensor with a good linearity over a wide pressure range. The present sensor outperforms most existing MEMS-based small footprint pressure sensors using graphene, silicon, and carbon nanotubes as sensitive materials, due to the high sensitivity. PMID:26988111

  6. Flexible suspended gate organic thin-film transistors for ultra-sensitive pressure detection

    NASA Astrophysics Data System (ADS)

    Zang, Yaping; Zhang, Fengjiao; Huang, Dazhen; Gao, Xike; di, Chong-An; Zhu, Daoben

    2015-03-01

    The utilization of organic devices as pressure-sensing elements in artificial intelligence and healthcare applications represents a fascinating opportunity for the next-generation electronic products. To satisfy the critical requirements of these promising applications, the low-cost construction of large-area ultra-sensitive organic pressure devices with outstanding flexibility is highly desired. Here we present flexible suspended gate organic thin-film transistors (SGOTFTs) as a model platform that enables ultra-sensitive pressure detection. More importantly, the unique device geometry of SGOTFTs allows the fine-tuning of their sensitivity by the suspended gate. An unprecedented sensitivity of 192 kPa-1, a low limit-of-detection pressure of <0.5 Pa and a short response time of 10 ms were successfully realized, allowing the real-time detection of acoustic waves. These excellent sensing properties of SGOTFTs, together with their advantages of facile large-area fabrication and versatility in detecting various pressure signals, make SGOTFTs a powerful strategy for spatial pressure mapping in practical applications.

  7. Flexible suspended gate organic thin-film transistors for ultra-sensitive pressure detection

    PubMed Central

    Zang, Yaping; Zhang, Fengjiao; Huang, Dazhen; Gao, Xike; Di, Chong-an; Zhu, Daoben

    2015-01-01

    The utilization of organic devices as pressure-sensing elements in artificial intelligence and healthcare applications represents a fascinating opportunity for the next-generation electronic products. To satisfy the critical requirements of these promising applications, the low-cost construction of large-area ultra-sensitive organic pressure devices with outstanding flexibility is highly desired. Here we present flexible suspended gate organic thin-film transistors (SGOTFTs) as a model platform that enables ultra-sensitive pressure detection. More importantly, the unique device geometry of SGOTFTs allows the fine-tuning of their sensitivity by the suspended gate. An unprecedented sensitivity of 192 kPa−1, a low limit-of-detection pressure of <0.5 Pa and a short response time of 10 ms were successfully realized, allowing the real-time detection of acoustic waves. These excellent sensing properties of SGOTFTs, together with their advantages of facile large-area fabrication and versatility in detecting various pressure signals, make SGOTFTs a powerful strategy for spatial pressure mapping in practical applications. PMID:25872157

  8. Pressure-Sensitive Paint Measurements on Surfaces with Non-Uniform Temperature

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy J.

    1999-01-01

    Pressure-sensitive paint (PSP) has become a useful tool to augment conventional pressure taps in measuring the surface pressure distribution of aerodynamic components in wind tunnel testing. While the PSP offers the advantage of a non-intrusive global mapping of the surface pressure, one prominent drawback to the accuracy of this technique is the inherent temperature sensitivity of the coating's luminescent intensity. A typical aerodynamic surface PSP test has relied on the coated surface to be both spatially and temporally isothermal, along with conventional instrumentation for an in situ calibration to generate the highest accuracy pressure mappings. In some tests however, spatial and temporal thermal gradients are generated by the nature of the test as in a blowing jet impinging on a surface. In these cases, the temperature variations on the painted surface must be accounted for in order to yield high accuracy and reliable data. A new temperature correction technique was developed at NASA Lewis to collapse a "family" of PSP calibration curves to a single intensity ratio versus pressure curve. This correction allows a streamlined procedure to be followed whether or not temperature information is used in the data reduction of the PSP. This paper explores the use of conventional instrumentation such as thermocouples and pressure taps along with temperature-sensitive paint (TSP) to correct for the thermal gradients that exist in aeropropulsion PSP tests. Temperature corrected PSP measurements for both a supersonic mixer ejector and jet cavity interaction tests are presented.

  9. Female SHR have greater blood pressure sensitivity and renal T cell infiltration following chronic NOS inhibition than males

    PubMed Central

    Brinson, Krystal N.; Elmarakby, Ahmed A.; Tipton, Ashlee J.; Crislip, G. Ryan; Yamamoto, Tatsuo; Baban, Babak

    2013-01-01

    Nitric oxide is a critical regulator of blood pressure (BP) and inflammation, and female spontaneously hypertensive rats (SHR) have higher renal nitric oxide bioavailability than males. We hypothesize that female SHR will have a greater rise in BP and renal T cell infiltration in response to nitric oxide synthase (NOS) inhibition than males. Both male and female SHR displayed a dose-dependent increase in BP to the nonspecific NOS inhibitor NG-nitro-l-arginine methyl ester (l-NAME: 2, 5, and 7 mg·kg−1·day−1 for 4 days each); however, females exhibited a greater increase in BP than males. Treatment of male and female SHR with 7 mg·kg−1·day−1 l-NAME for 2 wk significantly increased BP in both sexes; however, prior exposure to l-NAME only increased BP sensitivity to chronic NOS inhibition in females. l-NAME-induced hypertension increased renal T cell infiltration and indices of renal injury in both sexes, yet female SHR exhibited greater increases in Th17 cells and greater decreases in regulatory T cells than males. Chronic l-NAME was also associated with larger increases in renal cortical adhesion molecule expression in female SHR. The use of triple therapy to block l-NAME-mediated increases in BP attenuated l-NAME-induced increases in renal T cell counts and normalized adhesion molecule expression in SHR, suggesting that l-NAME-induced increases in renal T cells were dependent on both increases in BP and NOS inhibition. Our data suggest that NOS is critical in the ability of SHR, females in particular, to maintain BP and limit a pro-inflammatory renal T cell profile. PMID:23883679

  10. A highly sensitive pressure sensor using a double-layered graphene structure for tactile sensing.

    PubMed

    Chun, Sungwoo; Kim, Youngjun; Oh, Hyeong-Sik; Bae, Giyeol; Park, Wanjun

    2015-07-21

    In this paper, we propose a graphene sensor using two separated single-layered graphenes on a flexible substrate for use as a pressure sensor, such as for soft electronics. The working pressure corresponds to the range in which human perception recognizes surface morphologies. A specific design of the sensor structure drives the piezoresistive character due to the contact resistance between two graphene layers and the electromechanical properties of graphene itself. Accordingly, sensitivity in resistance change is given by two modes for low pressure (-0.24 kPa(-1)) and high pressure (0.039 kPa(-1)) with a crossover pressure (700 Pa). This sensor can detect infinitesimal pressure as low as 0.3 Pa with uniformly applied vertical force. With the attachment of the artificial fingerprint structure (AFPS) on the sensor, the detection ability for both the locally generated shear force and actual human touch confirms recognition of the surface morphology constructed by periodic structures. PMID:26098064

  11. Inhibition of focal adhesion kinase suppresses the adverse phenotype of endocrine-resistant breast cancer cells and improves endocrine response in endocrine-sensitive cells.

    PubMed

    Hiscox, Stephen; Barnfather, Peter; Hayes, Edd; Bramble, Pamela; Christensen, James; Nicholson, Robert I; Barrett-Lee, Peter

    2011-02-01

    Acquired resistance to endocrine therapy in breast cancer is a major clinical problem. Previous reports have demonstrated that cell models of acquired endocrine resistance have altered cell-matrix adhesion and a highly migratory phenotype, features which may impact on tumour spread in vivo. Focal adhesion kinase (FAK) is an intracellular kinase that regulates signalling pathways central to cell adhesion, migration and survival and its expression is frequently deregulated in breast cancer. In this study, we have used the novel FAK inhibitor PF573228 to address the role of FAK in the development of endocrine resistance. Whilst total-FAK expression was similar between endocrine-sensitive and endocrine-resistant MCF7 cells, FAK phosphorylation status (Y397 or Y861) was altered in resistance. PF573228 promoted a dose-dependent inhibition of FAK phosphorylation at Y397 but did not affect other FAK activation sites (pY407, pY576 and pY861). Endocrine-resistant cells were more sensitive to these inhibitory effects versus MCF7 (mean IC(50) for FAK pY397 inhibition: 0.43 μM, 0.05 μM and 0.13 μM for MCF7, TamR and FasR cells, respectively). Inhibition of FAK pY397 was associated with a reduction in TamR and FasR adhesion to, and migration over, matrix components. PF573228 as a single agent (0-1 μM) did not affect the growth of MCF7 cells or their endocrine-resistant counterparts. However, treatment of endocrine-sensitive cells with PF573228 and tamoxifen combined resulted in greater suppression of proliferation versus single agent treatment. Together these data suggest the importance of FAK in the process of endocrine resistance, particularly in the development of an aggressive, migratory cell phenotype and demonstrate the potential to improve endocrine response through combination treatment. PMID:20354780

  12. Characterization of pressure dynamics in an axisymmetric separating/reattaching flow using fast-responding pressure-sensitive paint

    NASA Astrophysics Data System (ADS)

    Bitter, Martin; Hara, Tatsuya; Hain, Rainer; Yorita, Daisuke; Asai, Keisuke; Kähler, Christian J.

    2012-12-01

    This collaborative work discusses the results of time-resolved pressure-sensitive paint measurements performed on a model of a generic spacecraft under sub- and transonic test conditions. It is shown that optical pressure measurements using an active layer from platinum-porphyrin complexes (PtTFPP) in combination with a polymer-ceramic base layer are able to measure dynamic flow phenomena in the trisonic wind tunnel facility up to sampling rates of 2 kHz. Low amplitude fluctuations in the order of 0.1 kPa were determined by means of this measurement technique. The buffet dynamics, as well as the spatial extent of the recirculation area in the near-wake, compare well with numerical predictions and PIV measurements. Furthermore, characteristic coherent pressure modes on the base were resolved, which were predicted by large-eddy simulations.

  13. Reliable prediction of electric spark sensitivity of nitramines: a general correlation with detonation pressure.

    PubMed

    Keshavarz, Mohammad Hossein; Pouretedal, Hamid Reza; Semnani, Abolfazl

    2009-08-15

    For nitramines, a general correlation has been introduced to predict electric spark sensitivity through detonation pressure. New method uses maximum obtainable detonation pressure as a fundamental relation so that it can be corrected for some nitramines which have some specific molecular structure. There is no need to use crystal density and heat of formation of nitramine explosives for predicting detonation pressure and electric spark sensitivity. The predicted electric spark sensitivities are compared with calculated results on the basis of quantum mechanical computations for some nitramines that latter can be applied. The root mean square (rms) deviations from experiment for new method and the predicted results of complicated quantum mechanical method are 1.18 and 3.49J, respectively. PMID:19188021

  14. Effects of inner materials on the sensitivity and phase depth of wireless inductive pressure sensors for monitoring intraocular pressure

    NASA Astrophysics Data System (ADS)

    Jang, Cheol-In; Shin, Kyeong-Sik; Kim, Mi Jeung; Yun, Kwang-Seok; Park, Ki Ho; Kang, Ji Yoon; Lee, Soo Hyun

    2016-03-01

    In this research, we developed wireless, inductive, pressure sensors with high sensitivity and investigated the effects of the inner materials (copper or ferrite) on the performance of the sensors. The proposed sensor is comprised of two parts, i.e., the top and the bottom parts. The top part includes a micro coil and a capacitor for the wireless transfer of data, and the bottom part includes the inner materials and a thick or thin flexible membrane to induce changes in the inductance. An anchor is used to assemble the top and bottom parts. The behavior of the sensor with copper was based on the eddy current effect, and, as the pressure increased, its resonance frequency increased, while its phase depth decreased exponentially. The principle of the sensor with ferrite was related to the effective permeability between a ferrite and a coil, and its response was the opposite of that with copper, i.e., as the pressure increased, the resonance frequency decreased linearly, and the phase depth increased linearly. These different operational mechanisms can be explained by the changes in the equations of inductance presented in this paper. After characterizing four different types of inductive pressure sensors in ambient air, one type of inductive pressure sensor was used to monitor the intraocular pressure (IOP) of a rabbit's eye as a biomedical application. The results showed that, in the animal tests, the measured responsivity and sensitivity were 16.7 kHz/mmHg and 1340 ppm/mmHg, respectively. These data indicate that the proposed sensor is a good candidate for monitoring IOP.

  15. [The sensitivity of mesenchymal stromal cell subpopulations with different times of adhesion property manifestation and derived from hemopoietic organs to growth factors EGF, bFGF, and PDGF].

    PubMed

    Molchanova, E A; Bueverova, E I; Starostin, V I; Domaratskaia, E I

    2011-01-01

    The action of three growth factors (EGF, bFGF, and PDGF) on mesenchymal stromal cell (MSC) subpopulations from mature bone marrow (BM) and rat embryo liver (EL) was investigated. These cells are plastic-adhesive and have different rates of adhesion (AC1-AC4 subpopulations). The efficiency of colony-formation, the size of colonies, and the number of early osteogenic progenitors with alkaline phosphatase activity in colonies and induced osteogenesis were analyzed. It was shown that EGF increased the number of bone marrow (BM) MSC colonies, but it had no influence on osteogenic differentiation. bFGF suppressed colony formation, but it stimulated both early and late stages of steogenesis. PDGF increased the size and the number of colonies in AC2 and AC3 subpopulations, but it stimulated only the ostegenesis terminal stage. The distinction between MSC subpopulations from two organs were found: MSC from EL had small osteogenic capacities and low sensitivity to grow factors; MSC from BM had no such characteristics. MSC subpopulations with different adhesion properties and from different tissues had compatible sensitivity to growth factors. Thus, these cells have no parent-progeny relationship. PMID:21506387

  16. The Role of the Kallikrein-Kinin System Genes in the Salt Sensitivity of Blood Pressure

    PubMed Central

    Gu, Dongfeng; Zhao, Qi; Kelly, Tanika N.; Hixson, James E.; Rao, Dabeeru C.; Cao, Jie; Chen, Jing; Li, Jianxin; Chen, Jichun; Ji, Xu; Hu, Dongsheng; Wang, Xushan; Liu, De-Pei; He, Jiang

    2012-01-01

    The current study comprehensively examined the association between common genetic variants of the kallikrein-kinin system (KKS) and blood pressure salt sensitivity. A 7-day low-sodium followed by a 7-day high-sodium dietary intervention was conducted among 1,906 Han Chinese participants recruited from 2003 to 2005. Blood pressure was measured by using a random-zero sphygmomanometer through the study. A total of 205 single nucleotide polymorphisms (SNPs) covering 11 genes of the KKS were selected for the analyses. Genetic variants of the bradykinin receptor B2 gene (BDKRB2) and the endothelin converting enzyme 1 gene (ECE1) showed significant associations with the salt-sensitivity phenotypes even after adjustment for multiple testing. Compared with the major G allele, the BDKRB2 rs11847625 minor C allele was significantly associated with increased systolic blood pressure responses to low-sodium intervention (P = 0.0001). Furthermore, a haplotype containing allele C was associated with an increased systolic blood pressure response to high-sodium intervention (P = 0.0009). Seven highly correlated ECE1 SNPs were shown to increase the diastolic blood pressure response to low-sodium intervention (P values ranged from 0.0003 to 0.002), with 2 haplotypes containing these 7 SNPs also associated with this same phenotype (P values ranged from 0.0004 to 0.002). In summary, genetic variants of the genes involved in the regulation of KKS may contribute to the salt sensitivity of blood pressure. PMID:23035147

  17. FBG based high sensitive pressure sensor and its low-cost interrogation system with enhanced resolution

    NASA Astrophysics Data System (ADS)

    Pachava, Vengal Rao; Kamineni, Srimannarayana; Madhuvarasu, Sai Shankar; Putha, Kishore; Mamidi, Venkata Reddy

    2015-12-01

    A fiber Bragg grating (FBG) pressure sensor with high sensitivity and resolution has been designed and demonstrated. The sensor is configured by firmly fixing the FBG with a metal bellows structure. The sensor works by means of measuring the Bragg wavelength shift of the FBG with respect to pressure change. From the experimental results, the pressure sensitivity of the sensor is found to be 90.6 pm/psi, which is approximately 4000 times as that of a bare fiber Bragg grating. A very good linearity of 99.86% is observed between the Bragg wavelength of the FBG and applied pressure. The designed sensor shows good repeatability with a negligible hysteresis error of ± 0.29 psi. A low-cost interrogation system that includes a long period grating (LPG) and a photodiode (PD) accompanied with simple electronic circuitry is demonstrated for the FBG sensor, which enables the sensor to attain high resolution of up to 0.025 psi. Thermal-strain cross sensitivity of the FBG pressure sensor is compensated using a reference FBG temperature sensor. The designed sensor can be used for liquid level, specific gravity, and static/dynamic low pressure measurement applications.

  18. Deployment of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades in Simulated Forward Flight

    NASA Technical Reports Server (NTRS)

    Watkins, A. Neal; Leighty, Bradley; Lipford, William E.; Wong, Oliver D.; Goodman, Kyle Z.; Crafton, Jim; Forlines, Alan; Goss, Larry P.; Gregory, James W.; Juliano, Thomas J.

    2012-01-01

    This paper will present details of a Pressure Sensitive Paint (PSP) system for measuring global surface pressures on the tips of rotorcraft blades in simulated forward flight at the 14- x 22-Foot Subsonic Tunnel at the NASA Langley Research Center. The system was designed to use a pulsed laser as an excitation source and PSP data was collected using the lifetime-based approach. With the higher intensity of the laser, this allowed PSP images to be acquired during a single laser pulse, resulting in the collection of crisp images that can be used to determine blade pressure at a specific instant in time. This is extremely important in rotorcraft applications as the blades experience dramatically different flow fields depending on their position in the rotor disk. Testing of the system was performed using the U.S. Army General Rotor Model System equipped with four identical blades. Two of the blades were instrumented with pressure transducers to allow for comparison of the results obtained from the PSP. Preliminary results show that the PSP agrees both qualitatively and quantitatively with both the expected results as well as with the pressure taps. Several areas of improvement have been indentified and are currently being developed.

  19. Solvent-based to waterbased adhesive-coated substrate retrofit. Volume 4. Film and label manufacturing case study, Flexcon Company, Incorporated. Final report, November 1992-June 1993

    SciTech Connect

    McMinn, B.W.; Snow, W.S.; Bowman, D.T.

    1995-12-01

    This volume discusses a visit to a site operated by Flexcon Company Incorporated, a pressure-sensitive adhesive coater, to collect information on the pollution prevention opportunities and barriers associated with waterbased adhesives. Chapter 2 includes the market profile and overall plant description. Chapter 3 provides a general process description. Chapter 4 discusses environmental issues associated with process conversion. Chapter 5 describes Flexcon`s waterbased adhesive formulation experience. Chapter 6 identifies the opportunities for future use waterbased and other adhesives at Flexcon.

  20. Assessment of musculoskeletal pain sensitivity and temporal summation by cuff pressure algometry: a reliability study.

    PubMed

    Graven-Nielsen, Thomas; Vaegter, Henrik Bjarke; Finocchietti, Sara; Handberg, Gitte; Arendt-Nielsen, Lars

    2015-11-01

    Chronic musculoskeletal pain is linked with sensitization, and standardized methods for assessment are needed. This study investigated (1) the test-retest reliability of computer-controlled cuff-pressure algometry (pain thresholds and temporal pain summation) on the arm and leg and (2) conditioned pain modulation (CPM) assessed by cuff algometry. The influences of age and gender were evaluated. On 2 different days, cuff pain threshold (cPPT), cuff pain tolerance (cPTT), and temporal summation of pain (TSP) by visual analog scale scores to 10 repeated cuff stimulations at cPTT intensity, as well as pressure pain threshold with handheld pressure algometry, were assessed in 136 healthy subjects. In one session, cuff pain sensitivity was also assessed before and after cold pressor-induced CPM. Good-to-excellent intraclass correlations (0.60-0.90) were demonstrated for manual and cuff algometry, and no systematic bias between sessions was found for cPPT, cPTT, and TSP on the leg and for cPTT and TSP on the arm. Cuff pressure pain threshold and cPTT were higher in men compared with women (P < 0.05). Middle-aged subjects had higher pressure pain threshold, but lower cPPT and cPTT, compared with younger subjects (P < 0.05). Temporal summation of pain was increased in women compared with men (P < 0.05). Cuff algometry was sensitive to CPM demonstrated as increased cPPT and cPTT and reduced TSP (P < 0.05). Reliability and sensitivity of computer-controlled cuff algometry for pain assessment is comparable with manual pressure algometry and constitutes a user-independent method for assessment of pain. Difference in age-related pain sensitivity between manual and cuff algometry should be further investigated. PMID:26172551

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

    PubMed

    Majumder, Abhijit; Sharma, Ashutosh; Ghatak, Animangsu

    2010-01-01

    A pressure-sensitive, nonreacting and nonfouling adhesive which can perform well both in air and underwater is very desirable because of its potential applications in various settings such as biomedical, marine, and automobile. Taking a clue from nature that many natural adhesive pads have complex structures underneath the outer adhesive layer, we have prepared thin elastic adhesive films with subsurface microstructures using PDMS (poly(dimethylsiloxane)) and investigated their performance underwater. The presence of embedded structure enhances the energy of adhesion considerably both in air and underwater. Furthermore, filling the channels with liquid of suitable surface tension modifies the internal stress profile, resulting into significant enhancement in adhesive performance. As this increase in adhesion is mediated by mechanics and not by surface chemistry, the presence of water does not alter its performance much. For the same reason, this adhesion mechanism works with both hydrophobic and hydrophilic surfaces. The adhesive can be reused because of its elastic surface. Moreover, unlike many other present-day adhesives, its performance does not decrease with time. PMID:20038181

  2. Free-stream static pressure measurements in the Longshot hypersonic wind tunnel and sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Grossir, Guillaume; Van Hove, Bart; Paris, Sébastien; Rambaud, Patrick; Chazot, Olivier

    2016-05-01

    The performance of fast-response slender static pressure probes is evaluated in the short-duration, cold-gas, VKI Longshot hypersonic wind tunnel. Free-stream Mach numbers range between 9.5 and 12, and unit Reynolds numbers are within 3-10 × 106/m. Absolute pressure sensors are fitted within the probes, and an inexpensive calibration method, suited to low static pressure environments (200-1000 Pa), is described. Transfer functions relating the probe measurements p w to the free-stream static pressure p ∞ are established for the Longshot flow conditions based on numerical simulations. The pressure ratios p w / p ∞ are found to be close to unity for both laminar and turbulent boundary layers. Weak viscous effects characterized by small viscous interaction parameters {bar{χ }}<1.5 are confirmed experimentally for probe aspect ratios of L/ D > 16.5 by installing multiple pressure sensors in a single probe. The effect of pressure orifice geometry is also evaluated experimentally and found to be negligible for either straight or chamfered holes, 0.6-1 mm in diameter. No sensitivity to probe angle of attack could be evidenced for α < 0.33°. Pressure measurements are compared to theoretical predictions assuming an isentropic nozzle flow expansion. Significant deviations from this ideal case and the Mach 14 contoured nozzle design are uncovered. Validation of the static pressure measurements is obtained by comparing shock wave locations on Schlieren photographs to numerical predictions using free-stream properties derived from the static pressure probes. While these results apply to the Longshot wind tunnel, the present methodology and sensitivity analysis can guide similar investigations for other hypersonic test facilities.

  3. A Stretchable Electronic Fabric Artificial Skin with Pressure-, Lateral Strain-, and Flexion-Sensitive Properties.

    PubMed

    Ge, Jin; Sun, Li; Zhang, Fu-Rui; Zhang, Ye; Shi, Lu-An; Zhao, Hao-Yu; Zhu, Hong-Wu; Jiang, Hai-Long; Yu, Shu-Hong

    2016-01-27

    A stretchable and multiple-force-sensitive electronic fabric based on stretchable coaxial sensor electrodes is fabricated for artificial-skin application. This electronic fabric, with only one kind of sensor unit, can simultaneously map and quantify the mechanical stresses induced by normal pressure, lateral strain, and flexion. PMID:26618615

  4. Step Response Characteristics of Polymer/Ceramic Pressure-Sensitive Paint

    PubMed Central

    Pandey, Anshuman; Gregory, James W.

    2015-01-01

    Experiments and numerical simulations have been used in this work to understand the step response characteristics of Polymer/Ceramic Pressure-Sensitive Paint (PC-PSP). A recently developed analytical model describing the essential physics in PC-PSP quenching kinetics is used, which includes the effect of both diffusion time scale and luminescent lifetime on the net response of PC-PSP. Step response simulations using this model enables an understanding of the effects of parameters, such as the diffusion coefficient of O2 in the polymer/ceramic coating, attenuation of excitation light, ambient luminescent lifetime, sensitivity, and the magnitude and direction of pressure change on the observed response time scales of PC-PSP. It was found that higher diffusion coefficient and greater light attenuation lead to faster response, whereas longer ambient lifetime and larger sensitivity lead to slower response characteristics. Due to the inherent non-linearity of the Stern-Volmer equation, response functions also change with magnitude and direction of the pressure change. Experimental results from a shock tube are presented where the effects of varying the roughness, pressure jump magnitude and luminophore probe have been studied. Model parameters have been varied to obtain a good fit to experimental results and this optimized model is then used to obtain the response time for a step decrease in pressure, an estimate of which is currently not obtainable from experiments. PMID:26404294

  5. A nanofiber based artificial electronic skin with high pressure sensitivity and 3D conformability.

    PubMed

    Zhong, Weibin; Liu, Qiongzhen; Wu, Yongzhi; Wang, Yuedan; Qing, Xing; Li, Mufang; Liu, Ke; Wang, Wenwen; Wang, Dong

    2016-06-16

    Pressure sensors with 3D conformability are highly desirable components for artificial electronic skin or e-textiles that can mimic natural skin, especially for application in real-time monitoring of human physiological signals. Here, a nanofiber based electronic skin with ultra-high pressure sensitivity and 3D conformability is designed and built by interlocking two elastic patterned nanofibrous membranes. The patterned membrane is facilely prepared by casting conductive nanofiber ink into a silicon mould to form an array of semi-spheroid-like protuberances. The protuberances composed of intertwined elastic POE nanofibers and PPy@PVA-co-PE nanofibers afford a tunable effective elastic modulus that is capable of capturing varied strains and stresses, thereby contributing to a high sensitivity for pressure sensing. This electronic skin-like sensor demonstrates an ultra-high sensitivity (1.24 kPa(-1)) below 150 Pa with a detection limit as low as about 1.3 Pa. The pixelated sensor array and a RGB-LED light are then assembled into a circuit and show a feasibility for visual detection of spatial pressure. Furthermore, a nanofiber based proof-of-concept wireless pressure sensor with a bluetooth module as a signal transmitter is proposed and has demonstrated great promise for wireless monitoring of human physiological signals, indicating a potential for large scale wearable electronic devices or e-skin. PMID:27250529

  6. Step Response Characteristics of Polymer/Ceramic Pressure-Sensitive Paint.

    PubMed

    Pandey, Anshuman; Gregory, James W

    2015-01-01

    Experiments and numerical simulations have been used in this work to understand the step response characteristics of Polymer/Ceramic Pressure-Sensitive Paint (PC-PSP). A recently developed analytical model describing the essential physics in PC-PSP quenching kinetics is used, which includes the effect of both diffusion time scale and luminescent lifetime on the net response of PC-PSP. Step response simulations using this model enables an understanding of the effects of parameters, such as the diffusion coefficient of O₂ in the polymer/ceramic coating, attenuation of excitation light, ambient luminescent lifetime, sensitivity, and the magnitude and direction of pressure change on the observed response time scales of PC-PSP. It was found that higher diffusion coefficient and greater light attenuation lead to faster response, whereas longer ambient lifetime and larger sensitivity lead to slower response characteristics. Due to the inherent non-linearity of the Stern-Volmer equation, response functions also change with magnitude and direction of the pressure change. Experimental results from a shock tube are presented where the effects of varying the roughness, pressure jump magnitude and luminophore probe have been studied. Model parameters have been varied to obtain a good fit to experimental results and this optimized model is then used to obtain the response time for a step decrease in pressure, an estimate of which is currently not obtainable from experiments. PMID:26404294

  7. A highly sensitive, low-cost, wearable pressure sensor based on conductive hydrogel spheres

    NASA Astrophysics Data System (ADS)

    Tai, Yanlong; Mulle, Matthieu; Aguilar Ventura, Isaac; Lubineau, Gilles

    2015-08-01

    Wearable pressure sensing solutions have promising future for practical applications in health monitoring and human/machine interfaces. Here, a highly sensitive, low-cost, wearable pressure sensor based on conductive single-walled carbon nanotube (SWCNT)/alginate hydrogel spheres is reported. Conductive and piezoresistive spheres are embedded between conductive electrodes (indium tin oxide-coated polyethylene terephthalate films) and subjected to environmental pressure. The detection mechanism is based on the piezoresistivity of the SWCNT/alginate conductive spheres and on the sphere-electrode contact. Step-by-step, we optimized the design parameters to maximize the sensitivity of the sensor. The optimized hydrogel sensor exhibited a satisfactory sensitivity (0.176 ΔR/R0/kPa-1) and a low detectable limit (10 Pa). Moreover, a brief response time (a few milliseconds) and successful repeatability were also demonstrated. Finally, the efficiency of this strategy was verified through a series of practical tests such as monitoring human wrist pulse, detecting throat muscle motion or identifying the location and the distribution of an external pressure using an array sensor (4 × 4).Wearable pressure sensing solutions have promising future for practical applications in health monitoring and human/machine interfaces. Here, a highly sensitive, low-cost, wearable pressure sensor based on conductive single-walled carbon nanotube (SWCNT)/alginate hydrogel spheres is reported. Conductive and piezoresistive spheres are embedded between conductive electrodes (indium tin oxide-coated polyethylene terephthalate films) and subjected to environmental pressure. The detection mechanism is based on the piezoresistivity of the SWCNT/alginate conductive spheres and on the sphere-electrode contact. Step-by-step, we optimized the design parameters to maximize the sensitivity of the sensor. The optimized hydrogel sensor exhibited a satisfactory sensitivity (0.176 ΔR/R0/kPa-1) and a low

  8. The Design and Optimization of a Highly Sensitive and Overload-Resistant Piezoresistive Pressure Sensor

    PubMed Central

    Meng, Xiawei; Zhao, Yulong

    2016-01-01

    A piezoresistive pressure sensor with a beam-membrane-dual-island structure is developed for micro-pressure monitoring in the field of aviation, which requires great sensitivity and overload resistance capacity. The design, fabrication, and test of the sensor are presented in this paper. By analyzing the stress distribution of sensitive elements using the finite element method, a novel structure incorporating sensitive beams with a traditional bossed diaphragm is built up. The proposed structure proved to be advantageous in terms of high sensitivity and high overload resistance compared with the conventional bossed diaphragm and flat diaphragm structures. Curve fittings of surface stress and deflection based on ANSYS simulation results are performed to establish the sensor equations. Fabricated on an n-type single crystal silicon wafer, the sensor chips are wire-bonded to a printed circuit board (PCB) and packaged for experiments. The static and dynamic characteristics are tested and discussed. Experimental results show that the sensor has a sensitivity as high as 17.339 μV/V/Pa in the range of 500 Pa at room temperature, and a high overload resistance of 200 times overpressure. Due to the excellent performance, the sensor can be applied in measuring micro-pressure lower than 500 Pa. PMID:27005627

  9. The Design and Optimization of a Highly Sensitive and Overload-Resistant Piezoresistive Pressure Sensor.

    PubMed

    Meng, Xiawei; Zhao, Yulong

    2016-01-01

    A piezoresistive pressure sensor with a beam-membrane-dual-island structure is developed for micro-pressure monitoring in the field of aviation, which requires great sensitivity and overload resistance capacity. The design, fabrication, and test of the sensor are presented in this paper. By analyzing the stress distribution of sensitive elements using the finite element method, a novel structure incorporating sensitive beams with a traditional bossed diaphragm is built up. The proposed structure proved to be advantageous in terms of high sensitivity and high overload resistance compared with the conventional bossed diaphragm and flat diaphragm structures. Curve fittings of surface stress and deflection based on ANSYS simulation results are performed to establish the sensor equations. Fabricated on an n-type single crystal silicon wafer, the sensor chips are wire-bonded to a printed circuit board (PCB) and packaged for experiments. The static and dynamic characteristics are tested and discussed. Experimental results show that the sensor has a sensitivity as high as 17.339 μV/V/Pa in the range of 500 Pa at room temperature, and a high overload resistance of 200 times overpressure. Due to the excellent performance, the sensor can be applied in measuring micro-pressure lower than 500 Pa. PMID:27005627

  10. Functionally Different Pads on the Same Foot Allow Control of Attachment: Stick Insects Have Load-Sensitive “Heel” Pads for Friction and Shear-Sensitive “Toe” Pads for Adhesion

    PubMed Central

    Labonte, David; Federle, Walter

    2013-01-01

    Stick insects (Carausius morosus) have two distinct types of attachment pad per leg, tarsal “heel” pads (euplantulae) and a pre-tarsal “toe” pad (arolium). Here we show that these two pad types are specialised for fundamentally different functions. When standing upright, stick insects rested on their proximal euplantulae, while arolia were the only pads in surface contact when hanging upside down. Single-pad force measurements showed that the adhesion of euplantulae was extremely small, but friction forces strongly increased with normal load and coefficients of friction were 1. The pre-tarsal arolium, in contrast, generated adhesion that strongly increased with pulling forces, allowing adhesion to be activated and deactivated by shear forces, which can be produced actively, or passively as a result of the insects' sprawled posture. The shear-sensitivity of the arolium was present even when corrected for contact area, and was independent of normal preloads covering nearly an order of magnitude. Attachment of both heel and toe pads is thus activated partly by the forces that arise passively in the situations in which they are used by the insects, ensuring safe attachment. Our results suggest that stick insect euplantulae are specialised “friction pads” that produce traction when pressed against the substrate, while arolia are “true” adhesive pads that stick to the substrate when activated by pulling forces. PMID:24349156

  11. Pressure- and Temperature-Sensitive Paint at 0.3-m Transonic Cryogenic Tunnel

    NASA Technical Reports Server (NTRS)

    Watkins, A. Neal; Leighty, Bradley D.; Lipford, William E.; Goodman, Kyle Z.

    2015-01-01

    Recently both Pressure- and Temperature-Sensitive Paint experiments were conducted at cryogenic conditions in the 0.3-m Transonic Cryogenic Tunnel at NASA Langley Research Center. This represented a re-introduction of the techniques to the facility after more than a decade, and provided a means to upgrade the measurements using newer technology as well as demonstrate that the techniques were still viable in the facility. Temperature-Sensitive Paint was employed on a laminar airfoil for transition detection and Pressure-Sensitive Paint was employed on a supercritical airfoil. This report will detail the techniques and their unique challenges that need to be overcome in cryogenic environments. In addition, several optimization strategies will also be discussed.

  12. A high sensitivity pressure sensor based on two-dimensional photonic crystal

    NASA Astrophysics Data System (ADS)

    Tao, Shangbin; Chen, Deyuan; Wang, Juebin; Qiao, Jing; Duan, Yali

    2016-06-01

    In this paper, we propose and simulate a pressure sensor based on two-dimensional photonic crystal with the high quality factor and sensitivity. The sensor is formed by the coupling of two photonic crystal based waveguides and one nanocavity. The photonic crystal with the triangular lattice is composed of GaAs rods. The detailed structures of the waveguides and nanocavity are optimized to achieve better quality factor and sensitivity of the sensor. For the optimized structures, the resonant wavelength of the sensor has a linear redshift as increasing the applied pressure in the range of 0-2 GPa, and the quality factor keeps unchanged nearly. The optimized quality factor is around 1500, and the sensitivity is up to 13.9 nm/GPa.

  13. Use of Pressure Sensitive Paint for Diagnostics in Turbomachinery Flows With Shocks

    NASA Technical Reports Server (NTRS)

    Lepicovsky, Jan; Bencic, Timothy J.

    2001-01-01

    The technology of pressure sensitive paint (PSP) is well established in external aerodynamics. In internal flows in narrow channels and in turbomachinery cascades, however, there are still unresolved problems. In particular, the internal flows with complex shock structures inside highly curved channels present a challenge. It is not always easy and straightforward to distinguish between true signals and "ghost" images due to multiple internal reflections in narrow channels. To address some of the problems, investigations were first carried out in a narrow supersonic channel of Mach number 2.5. A single wedge or a combination of two wedges were used to generate a complex shock wave structure in the flow. The experience gained in a small supersonic channel was used for surface pressure measurements on the stator vane of a supersonic throughflow fan. The experimental results for several fan operating conditions are shown in a concise form, including performance map points, midspan static tap pressure distributions, and vane suction side pressure fields. Finally, the PSP technique was used in the NASA transonic flutter cascade to compliment flow visualization data and to acquire backwall pressure fields to assess the cascade flow periodicity. A summary of shortcomings of the pressure sensitive paint technology for internal flow application and lessons learned are presented in the conclusion of the paper.

  14. Surface-modified piezoresistive nanocomposite flexible pressure sensors with high sensitivity and wide linearity

    NASA Astrophysics Data System (ADS)

    Shu, Yi; Tian, He; Yang, Yi; Li, Cheng; Cui, Yalong; Mi, Wentian; Li, Yuxing; Wang, Zhe; Deng, Ningqin; Peng, Bo; Ren, Tian-Ling

    2015-04-01

    Flexible pressure sensors working in a low pressure range (<10 kPa) have become an important part of recent research due to their applications in ``artificial skin'', foldable electronics and so on. Several efforts have been focused on the high sensitivity of devices with the neglect of linearity which is essential for real applications. Here, we present a device with a new Gaussian random distribution contact surface profile and a novel contact and piezoresistive composite working principle by numerical simulation, which predicts the combination of wide linearity and high sensitivity. With the modified surfaces' contact effect and the piezoresistive capability of these nanocomposite structures, an outstanding linearity can be achieved all along the measuring scale from 0 to 14 kPa, with a high sensitivity around 13.8 kPa-1. The random distribution surface also provides the device with fine stability and reproducibility, which are validated in the test.Flexible pressure sensors working in a low pressure range (<10 kPa) have become an important part of recent research due to their applications in ``artificial skin'', foldable electronics and so on. Several efforts have been focused on the high sensitivity of devices with the neglect of linearity which is essential for real applications. Here, we present a device with a new Gaussian random distribution contact surface profile and a novel contact and piezoresistive composite working principle by numerical simulation, which predicts the combination of wide linearity and high sensitivity. With the modified surfaces' contact effect and the piezoresistive capability of these nanocomposite structures, an outstanding linearity can be achieved all along the measuring scale from 0 to 14 kPa, with a high sensitivity around 13.8 kPa-1. The random distribution surface also provides the device with fine stability and reproducibility, which are validated in the test. Electronic supplementary information (ESI) available. See DOI

  15. Bronchial biopsy evidence for leukocyte infiltration and upregulation of leukocyte-endothelial cell adhesion molecules 6 hours after local allergen challenge of sensitized asthmatic airways.

    PubMed Central

    Montefort, S; Gratziou, C; Goulding, D; Polosa, R; Haskard, D O; Howarth, P H; Holgate, S T; Carroll, M P

    1994-01-01

    We have examined the mucosal changes occurring in bronchial biopsies from six atopic asthmatics 5-6 h after local endobronchial allergen challenge and compared them with biopsies from saline-challenged segments from the same subjects at the same time point. All the subjects developed localized bronchoconstriction in the allergen-challenged segment and had a decrease in forced expiratory volume in 1 s (FEV1) (P < 0.01) and a decrease in their methacholine provocative concentration of agonist required to reduce FEV1 from baseline by 20% (P < 0.05) 24 h postchallenge. At 6 h we observed an increase in neutrophils (P = 0.03), eosinophils (P = 0.025), mast cells (P = 0.03), and CD3+ lymphocytes (P = 0.025), but not in CD4+ or CD8+ lymphocyte counts. We also detected an increase in endothelial intercellular adhesion molecule type 1 (P < 0.05) and E-selectin (P < 0.005), but not vascular cell adhesion molecule type 1 expression with a correlative increase in submucosal and epithelial LFA+ leucocytes (P < 0.01). Thus, in sensitized asthmatics, local endobronchial allergen instillation leads to an increased inflammatory cell infiltrate of the airway mucosa that involves upregulation of specific adhesion molecules expressed on the microvasculature. Images PMID:7512980

  16. Sensitivity enhancement using annealed polymer optical-fibre-based sensors for pressure sensing applications

    NASA Astrophysics Data System (ADS)

    Pospori, A.; Marques, C. A. F.; Sáez-Rodríguez, D.; Nielsen, K.; Bang, O.; Webb, D. J.

    2016-05-01

    Thermal annealing can be used to induce a permanent negative Bragg wavelength shift for polymer fibre grating sensors and it was originally used for multiplexing purposes. Recently, researchers showed that annealing can also provide additional benefits, such as strain and humidity sensitivity enhancement and augmented temperature operational range. The annealing process can change both the optical and mechanical properties of the fibre. In this paper, the annealing effects on the stress and force sensitivities of PMMA fibre Bragg grating sensors are investigated. The incentive for that investigation was an unexpected behaviour observed in an array of sensors which were used for liquid level monitoring. One sensor exhibited much lower pressure sensitivity and that was the only one that was not annealed. To further investigate the phenomenon, additional sensors were photo-inscribed and characterised with regard their stress and force sensitivities. Then, the fibres were annealed by placing them in hot water, controlling with that way the humidity factor. After annealing, stress and force sensitivities were measured again. The results show that the annealing can improve the stress and force sensitivity of the devices. This can provide better performing sensors for use in stress, force and pressure sensing applications.

  17. Enteral n-3 fatty acids and micronutrients enhance percentage of positive neutrophil and lymphocyte adhesion molecules: a potential mediator of pressure ulcer healing in critically ill patients.

    PubMed

    Theilla, Miriam; Schwartz, Betty; Zimra, Yael; Shapiro, Haim; Anbar, Ronit; Rabizadeh, Esther; Cohen, Jonathan; Singer, Pierre

    2012-04-01

    n-3 Fatty acids are recognised as influencing both wound healing and immunity. We assessed the impact of a fish oil- and micronutrient-enriched formula (study formula) on the healing of pressure ulcers and on immune function in critically ill patients in an intensive care unit. A total of forty patients with pressure ulcers and receiving nutritional support were enrolled (intervention group, n 20, received study formula; and a control group, n 20, received an isoenergetic formula). Total and differential leucocyte count and percentage of adhesion molecule positive granulocyte and lymphocyte cells (CD11a, CD11b, CD18 and CD49b) were measured on days 0, 7 and 14. Percentage of positive lymphocytes for CD54, CD49b, CD49d and CD8 were also measured on days 0, 7 and 14. The state of pressure ulcers was assessed by using the pressure ulcer scale for healing tool score on days 7, 14 and 28 of treatment. No between-group differences in patient demographics, anthropometry or diagnostic class were observed. Patients who received the study formula showed significant increases in the percentage of positive CD18 and CD11a lymphocytes and of CD49b granulocytes as compared to controls (P < 0·05). While the severity of pressure ulcers was not significantly different between the two groups on admission, severity increased significantly over time for the control group (P < 0·05), but not for the study group. The present study suggests that a fish oil- and micronutrient-enriched formula may prevent worsening of pressure ulcers and that this effect may be mediated by an effect on adhesion molecule expression. PMID:22040465

  18. A subambient pressure ionization with nanoelectrospray (SPIN) source and interface for improved sensitivity in mass spectrometry

    SciTech Connect

    Page, Jason S.; Tang, Keqi; Kelly, Ryan T.; Smith, Richard D.

    2008-03-15

    Subambient Pressure Ionization with Nanoelectrospray (SPIN), an electrospray ionization source that operates at 30 Torr inside the first vacuum chamber of a mass spectrometer, has been demonstrated for reversed-phase liquid chromatography-mass spectrometry analysis of a protein tryptic digest solution. A 5–12-fold improvement in sensitivity relative to a standard atmospheric pressure ESI source was observed for a variety of detected peptides. The low liquid chromatographic flow rate (300 nL/min) allowed stable electrospray to be established before the onset of electrical discharge, and the higher operating pressure of the SPIN source relative to previous low-pressure ESI source designs prevented the solvents from freezing. The range of accessible flow rates for the SPIN source was also extended to 2.5 μL/min by using an array of electrospray emitters that divided the flow to 6 discrete electrosprays.

  19. On the sensitivity to partial pressure of oxygen of the mobility in cadmium oxide

    NASA Astrophysics Data System (ADS)

    Grado-Caffaro, M. A.; Grado-Caffaro, M.

    2015-11-01

    The partial pressure of oxygen during the deposition process of cadmium oxide is a crucial quantity whose influence on the electrical and optical properties of this material is really very significant (consider, for example, the experimental technique known as activated reactive evaporation). In fact, this paper is a theoretical formulation to evaluate the sensitivity changes of the aforementioned pressure of the electron drift-mobility and velocity in CdO. Indeed, as we will see later, given that the electron relaxation time depends upon the oxygen partial pressure, then the electron drift-mobility, mean free path and velocity also depend on this pressure. Relevant calculations involving the above physical quantities are carried out.

  20. A highly sensitive, low-cost, wearable pressure sensor based on conductive hydrogel spheres.

    PubMed

    Tai, Yanlong; Mulle, Matthieu; Aguilar Ventura, Isaac; Lubineau, Gilles

    2015-09-21

    Wearable pressure sensing solutions have promising future for practical applications in health monitoring and human/machine interfaces. Here, a highly sensitive, low-cost, wearable pressure sensor based on conductive single-walled carbon nanotube (SWCNT)/alginate hydrogel spheres is reported. Conductive and piezoresistive spheres are embedded between conductive electrodes (indium tin oxide-coated polyethylene terephthalate films) and subjected to environmental pressure. The detection mechanism is based on the piezoresistivity of the SWCNT/alginate conductive spheres and on the sphere-electrode contact. Step-by-step, we optimized the design parameters to maximize the sensitivity of the sensor. The optimized hydrogel sensor exhibited a satisfactory sensitivity (0.176 ΔR/R0/kPa(-1)) and a low detectable limit (10 Pa). Moreover, a brief response time (a few milliseconds) and successful repeatability were also demonstrated. Finally, the efficiency of this strategy was verified through a series of practical tests such as monitoring human wrist pulse, detecting throat muscle motion or identifying the location and the distribution of an external pressure using an array sensor (4 × 4). PMID:26288336

  1. A highly sensitive pressure sensor using a double-layered graphene structure for tactile sensing

    NASA Astrophysics Data System (ADS)

    Chun, Sungwoo; Kim, Youngjun; Oh, Hyeong-Sik; Bae, Giyeol; Park, Wanjun

    2015-07-01

    In this paper, we propose a graphene sensor using two separated single-layered graphenes on a flexible substrate for use as a pressure sensor, such as for soft electronics. The working pressure corresponds to the range in which human perception recognizes surface morphologies. A specific design of the sensor structure drives the piezoresistive character due to the contact resistance between two graphene layers and the electromechanical properties of graphene itself. Accordingly, sensitivity in resistance change is given by two modes for low pressure (-0.24 kPa-1) and high pressure (0.039 kPa-1) with a crossover pressure (700 Pa). This sensor can detect infinitesimal pressure as low as 0.3 Pa with uniformly applied vertical force. With the attachment of the artificial fingerprint structure (AFPS) on the sensor, the detection ability for both the locally generated shear force and actual human touch confirms recognition of the surface morphology constructed by periodic structures.In this paper, we propose a graphene sensor using two separated single-layered graphenes on a flexible substrate for use as a pressure sensor, such as for soft electronics. The working pressure corresponds to the range in which human perception recognizes surface morphologies. A specific design of the sensor structure drives the piezoresistive character due to the contact resistance between two graphene layers and the electromechanical properties of graphene itself. Accordingly, sensitivity in resistance change is given by two modes for low pressure (-0.24 kPa-1) and high pressure (0.039 kPa-1) with a crossover pressure (700 Pa). This sensor can detect infinitesimal pressure as low as 0.3 Pa with uniformly applied vertical force. With the attachment of the artificial fingerprint structure (AFPS) on the sensor, the detection ability for both the locally generated shear force and actual human touch confirms recognition of the surface morphology constructed by periodic structures. Electronic

  2. Pressure-Sensitive Paint Investigation of Double-Delta Wing Vortex Flow Manipulation

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.; Gonzalez, Hugo A.

    2004-01-01

    A pressure-sensitive paint (PSP) technique was applied in a wind tunnel experiment in the NASA Langley Research Center 8-Foot Transonic Pressure Tunnel to quantify the effect of wing fillets on the global vortex-induced surface static pressure field about a sharp leading-edge 76o/40o double delta wing, or strake-wing, model at subsonic and transonic speeds. Global calibrations of the PSP were obtained at M = 0.50, 0.70, 0.85, 0.95, and 1.20, a Reynolds number per unit length of 2.0 million, and angles of attack from 10 degrees to 20 degrees using an in-situ method featuring the simultaneous acquisition of electronically-scanned pressures (ESP) at discrete locations on the model. The mean error in the PSP measurements relative to the ESP data was approximately 2 percent or less at M = 0.50 to 0.85 but increased to several percent at M =0.95 and 1.20. The PSP pressure distributions and pseudo-colored planform view pressure maps clearly revealed the vortex-induced pressure signatures at all Mach numbers and angles of attack. Small fillets having a parabolic or diamond planform situated at the strake-wing intersection were designed to manipulate the vortical flows by, respectively, removing the leading-edge discontinuity or introducing additional discontinuities. The fillets caused global changes in the vortex-dominated surface pressure field that were effectively captured in the PSP measurements. The vortex surface pressure signatures were compared to available off-surface vortex cross-flow structures obtained using a laser vapor screen (LVS) flow visualization technique. The fillet effects on the PSP pressure distributions and the observed leading-edge vortex flow characteristics were consistent with the trends in the measured lift, drag, and pitching moment coefficients.

  3. Pressure-Sensitive Paint Investigation of Double-Delta Wing Vortex Flow Manipulation

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.; Gonzalez, Hugo A.

    2005-01-01

    A pressure-sensitive paint (PSP) technique was applied in a wind tunnel experiment in the NASA Langley Research Center 8-Foot Transonic Pressure Tunnel to quantify the effect of wing fillets on the global vortex-induced surface static pressure field about a sharp leading-edge 76 deg/40 deg double delta wing, or strake-wing, model at subsonic and transonic speeds. Global calibrations of the PSP were obtained at M = 0.50, 0.70, 0.85, 0.95, and 1.20, a Reynolds number per unit length of 2.0 million, and angles of attack from 10 degrees to 30 degrees using an in-situ method featuring the simultaneous acquisition of electronically-scanned pressures (ESP) at discrete locations on the model. The mean error in the PSP measurements relative to the ESP data was approximately 2 percent or less at M = 0.50 to 0.85 but increased to several percent at M = 0.95 and 1.20. The PSP pressure distributions and pseudo-colored planform view pressure maps clearly revealed the vortex-induced pressure signatures at all Mach numbers and angles of attack. Small fillets having a parabolic or diamond planform situated at the strake-wing intersection were designed to manipulate the vortical flows by, respectively, removing the leading-edge discontinuity or introducing additional discontinuities. The fillets caused global changes in the vortex-dominated surface pressure field that were effectively captured in the PSP measurements. The vortex surface pressure signatures were compared to available off-surface vortex cross-flow structures obtained using a laser vapor screen (LVS) flow visualization technique. The fillet effects on the PSP pressure distributions and the observed leading-edge vortex flow characteristics were consistent with the trends in the measured lift, drag, and pitching moment coefficients.

  4. Highly sensitive contact pressure measurements using FBG patch in endotracheal tube cuff

    NASA Astrophysics Data System (ADS)

    Correia, R.; Blackman, O. R.; Hernandez, F. U.; Korposh, S.; Morgan, S. P.; Hayes-Gill, B. R.; James, S. W.; Evans, D.; Norris, A.

    2016-05-01

    A method for measuring the contact pressure between an endotracheal tube cuff and the trachea was designed and developed by using a fibre Bragg grating (FBG) based optical fibre sensor. The FBG sensor is encased in an epoxy based UV-cured cuboid patch and transduces the transversely loaded pressure into an axial strain that induces wavelength shift of the Bragg reflection. The polymer patch was created by using a PTFE based mould and increases tensile strength and sensitivity of the bare fibre FBG to pressure to 2.10×10-2 nm/kPa. The characteristics of the FBG patch allow for continuous measurement of contact pressure. The measurement of contact pressure was demonstrated by the use of a 3D printed model of a human trachea. The influence of temperature on the measurements is reduced significantly by the use of a second FBG sensor patch that is not in contact with the trachea. Intracuff pressure measurements performed using a commercial manometer agreed well with the FBG contact pressure measurements.

  5. A subambient pressure ionization with nanoelectrospray (SPIN) source and interface for improved sensitivity in mass spectrometry

    PubMed Central

    Page, Jason S.; Tang, Keqi; Kelly, Ryan T.; Smith, Richard D.

    2008-01-01

    An electrospray ionization mass spectrometry (ESI-MS) source and interface has been designed that enables efficient ion production and transmission in a 30 Torr pressure environment using solvents compatible with typical reversed-phase liquid chromatography (RPLC) separations. In this design, the electrospray emitter is located inside the mass spectrometer in the same region as an electrodynamic ion funnel. This avoids the use of a conductance limit ion inlet, as required by a conventional atmospheric pressure ESI source, and allows more efficient ion transmission to the mass analyzer. The new source, titled Subambient Pressure Ionization with Nanoelectrospray (SPIN), improves instrument sensitivity, increases the understanding of the electrospray process, and enables new electrospray interface designs. Performance of the SPIN source was evaluated by electrospraying standard solutions at 300 nL/min, and comparing results with those obtained from a standard atmospheric pressure ESI source that used a heated capillary inlet. The importance of desolvation was also investigated by electrospraying at different flow rates, which showed that the ion funnel provided an effective desolvation region to aid the creation of gas phase analyte ions. This initial study demonstrated a ∼ 5-fold improvement in sensitivity when the SPIN source was used compared to a standard atmospheric pressure ESI source. PMID:18237189

  6. Method development for compensating temperature effects in pressure sensitive paint measurements

    NASA Technical Reports Server (NTRS)

    Demandante, Carlo Greg N.

    1994-01-01

    Pressure sensitive luminescent paints (PSP) have recently emerged as a viable technique for aerodynamic pressure measurements. The technique uses a surface coating which contains probe molecules that luminesce when excited by light of an appropriate wavelength. The photoluminescence of these materials is known to be quenched by the presence of molecular oxygen. Since oxygen is a fixed mole fraction of the air, the coating's luminescence intensity varies inversely with air pressure. Digital imaging of the luminescence varying across a coated surface produces a pressure distribution map over that surface. One difficulty encountered with this technique is the temperature effect on the luminescence intensity. Present PSP formulations have significant sensitivity to temperature. At the moment, the most practical way of correcting for temperature effects is to calibrate the paint in place at the operating temperatures by using a few well-placed pressure taps. This study is looking at development of temperature indicating coatings that can be applied and measured concurrently with PSP, and use the temperature measurement to compute the correct pressure. Two methods for this dual paint formulation are proposed. One method will use a coating that consists of temperature sensitive phosphors in a polymer matrix. This is similar in construction to PSP, except that the probe molecules used are selected primarily for their temperature sensitivity. Both organic phosphors (e.g., europium thenoyltrifluoroacetonate, bioprobes) and inorganic phosphors (e.g., Mg4(F)GeO6:Mn, La2O2S:Eu, Radelin Type phosphors, Sylvania Type phosphors) will be evaluated for their temperature sensing potential. The next method will involve a novel coating composing of five membered heterocyclic conducting polymers which are known to show temperature dependent luminescence (e.g., poly(3-alkylthiopene), poly(3-alkylselenophene), poly(3-alkylfuran)). Both methods will involve applying a bottom layer of

  7. Organo-Chlorinated Thin Films Deposited by Atmospheric Pressure Plasma-Enhanced Chemical Vapor Deposition for Adhesion Enhancement between Rubber and Zinc-Plated Steel Monofilaments.

    PubMed

    Vandenabeele, Cédric; Bulou, Simon; Maurau, Rémy; Siffer, Frederic; Belmonte, Thierry; Choquet, Patrick

    2015-07-01

    A continuous-flow plasma process working at atmospheric pressure is developed to enhance the adhesion between a rubber compound and a zinc-plated steel monofilament, with the long-term objective to find a potential alternative to the electrolytic brass plating process, which is currently used in tire industry. For this purpose, a highly efficient tubular dielectric barrier discharge reactor is built to allow the continuous treatment of "endless" cylindrical substrates. The best treatment conditions found regarding adhesion are Ar/O2 plasma pretreatment, followed by the deposition from dichloromethane of a 75 nm-thick organo-chlorinated plasma polymerized thin film. Ar/O2 pretreatment allows the removal of organic residues, coming from drawing lubricants, and induces external growth of zinc oxide. The plasma layer has to be preferably deposited at low power to conserve sufficient hydrocarbon moieties. Surface analyses reveal the complex chemical mechanism behind the establishment of strong adhesion levels, more than five times higher after the plasma treatment. During the vulcanization step, superficial ZnO reacts with the chlorinated species of the thin film and is converted into porous and granular bump-shaped ZnwOxHyClz nanostructures. Together, rubber additives diffuse through the plasma layer and lead to the formation of zinc sulfide on the substrate surface. Hence, two distinct interfaces, rubber/thin film and thin film/substrate, are established. On the basis of these observations, hypotheses explaining the high bonding strength results are formulated. PMID:26069994

  8. Preparation of an Adhesive in Emulsion for Maxillofacial Prosthetic

    PubMed Central

    Sánchez-García, Judith A.; Ortega, Alejandra; Barceló-Santana, Federico H.; Palacios-Alquisira, Joaquín

    2010-01-01

    Maxillofacial prostheses is a dental medicine specialty aimed at restoring anatomical facial defects caused by cancer, trauma or congenital malformations through an artificial device, which is commonly attached to the skin with the help of an adhesive. The purpose of our research was to develop a pressure-sensitive adhesive (PSA) based on acrylic monomers, characterizing and determining its drying kinetics, that is to say the time it takes to lose 50 to 90% of its moisture. The adhesive synthesis was realized by means of emulsion polymerization; the composition of formulations was: (AA-MMA-EA) and (AA-MMA-2EHA) with different molar ratios. The formulation based on (AA-MMA-2EHA) with 50 w% of solids, presented good adhesive properties such as tack, bond strength, and short drying time. We propose this formulation as a PSA, because it offers an alternative for systemically compromised patients, by less irritation compared to organic solvent-based adhesives. PMID:21152308

  9. Pressure Sensitive Paint Measurements on 15% Scale Rotor Blades in Hover

    NASA Technical Reports Server (NTRS)

    Wong, Oliver D.; Watkins, Anthony Neal; Ingram, JoAnne L.

    2005-01-01

    This paper describes a proof of concept test to examine the feasibility of using pressure sensitive paint (PSP) to measure the pressure distributions on a rotor in hover. The test apparatus consisted of the US Army 2-meter Rotor Test Stand (2MRTS) and 15% scale swept tip rotor blades. Two camera/rotor separations were examined: 0.76 and 1.35 radii. The outer 15% of each blade was painted with PSP. Intensity and lifetime based PSP measurement techniques were attempted. Data were collected from all blades at thrust coefficients ranging from 0.004 to 0.009.

  10. Sound pressure enhances the hearing sensitivity of Chaetodon butterflyfishes on noisy coral reefs.

    PubMed

    Tricas, Timothy C; Boyle, Kelly S

    2015-05-15

    Butterflyfishes are conspicuous members of coral reefs that communicate with acoustic signals during social interactions with mates and other conspecifics. Members of the genus Chaetodon have a laterophysic connection (LC) - a unique association of anterior swim bladder horns and the cranial lateral line - but the action of the LC system on auditory sensitivity is unexplored. Here, we show in baseline auditory evoked potential threshold experiments that Forcipiger flavissimus (which lacks swim bladder horns and LC) is sensitive to sound tones from 100 Hz up to 1000 Hz, and that thresholds for three species of Chaetodon are 10-15 dB lower, with extended hearing ranges up to 1700-2000 Hz. The relatively high thresholds to sound pressure and low pass response near 500 Hz for all four species are consistent with a primary sensitivity to hydrodynamic particle acceleration rather than sound pressure. Deflation of the swim bladder in F. flavissimus had no measurable effect on auditory sensitivity. In contrast, displacement of gas from the swim bladder horns in Chaetodon multicinctus and Chaetodon auriga increased thresholds (decreased sensitivity) by 5-20 dB, with the greatest effect at 600 Hz. The evolution of swim bladder horns associated with the LC system in Chaetodon species has increased hearing sensitivity through sound pressure transduction in the frequency bands used for social acoustic communication. The close affiliative behaviors that are common in Chaetodon species and other butterflyfish facilitate sound perception and acoustic communication at close distances relative to the high background noise levels found in their natural reef environment. PMID:25722003

  11. A nanofiber based artificial electronic skin with high pressure sensitivity and 3D conformability

    NASA Astrophysics Data System (ADS)

    Zhong, Weibin; Liu, Qiongzhen; Wu, Yongzhi; Wang, Yuedan; Qing, Xing; Li, Mufang; Liu, Ke; Wang, Wenwen; Wang, Dong

    2016-06-01

    Pressure sensors with 3D conformability are highly desirable components for artificial electronic skin or e-textiles that can mimic natural skin, especially for application in real-time monitoring of human physiological signals. Here, a nanofiber based electronic skin with ultra-high pressure sensitivity and 3D conformability is designed and built by interlocking two elastic patterned nanofibrous membranes. The patterned membrane is facilely prepared by casting conductive nanofiber ink into a silicon mould to form an array of semi-spheroid-like protuberances. The protuberances composed of intertwined elastic POE nanofibers and PPy@PVA-co-PE nanofibers afford a tunable effective elastic modulus that is capable of capturing varied strains and stresses, thereby contributing to a high sensitivity for pressure sensing. This electronic skin-like sensor demonstrates an ultra-high sensitivity (1.24 kPa-1) below 150 Pa with a detection limit as low as about 1.3 Pa. The pixelated sensor array and a RGB-LED light are then assembled into a circuit and show a feasibility for visual detection of spatial pressure. Furthermore, a nanofiber based proof-of-concept wireless pressure sensor with a bluetooth module as a signal transmitter is proposed and has demonstrated great promise for wireless monitoring of human physiological signals, indicating a potential for large scale wearable electronic devices or e-skin.Pressure sensors with 3D conformability are highly desirable components for artificial electronic skin or e-textiles that can mimic natural skin, especially for application in real-time monitoring of human physiological signals. Here, a nanofiber based electronic skin with ultra-high pressure sensitivity and 3D conformability is designed and built by interlocking two elastic patterned nanofibrous membranes. The patterned membrane is facilely prepared by casting conductive nanofiber ink into a silicon mould to form an array of semi-spheroid-like protuberances. The

  12. Novel highly sensitive and wearable pressure sensors from conductive three-dimensional fabric structures

    NASA Astrophysics Data System (ADS)

    Li, Jianfeng; Xu, Bingang

    2015-12-01

    Pressure sensors based on three-dimensional fabrics have all the excellent properties of the textile substrate: excellent compressibility, good air permeability and moisture transmission ability, which will find applications ranging from the healthcare industry to daily usage. In this paper, novel pressure sensors based on 3D spacer fabrics have been developed by a proposed multi-coating method. By this coating method, carbon black can be coated uniformly on the silicon elastomer which is attached and slightly cured on the 3D fabric surface beforehand. The as-made pressure sensors have good conductivity and can measure external pressure up to 283 kPa with an electrical conductivity range of 9.8 kΩ. The sensitivity of 3D fabric pressure sensors can be as high as 50.31×10-3 kPa-1, which is better than other textile based pressure sensors. When the as-made sensors are pressed, their electrical resistance will decrease because of more conductive connections and bending of fibers in the spacer layer. The sensing mechanism related to fiber bending has been explored by using an equivalent resistance model. The newly developed 3D sensor devices can be designed to exhibit different sensing performances by simply changing the structures of fabric substrate, which endows this kind of device more flexibility in related applications.

  13. Behavior of plant plasma membranes under hydrostatic pressure as monitored by fluorescent environment-sensitive probes.

    PubMed

    Roche, Yann; Klymchenko, Andrey S; Gerbeau-Pissot, Patricia; Gervais, Patrick; Mély, Yves; Simon-Plas, Françoise; Perrier-Cornet, Jean-Marie

    2010-08-01

    We monitored the behavior of plasma membrane (PM) isolated from tobacco cells (BY-2) under hydrostatic pressures up to 3.5kbar at 30 degrees C, by steady-state fluorescence spectroscopy using the newly introduced environment-sensitive probe F2N12S and also Laurdan and di-4-ANEPPDHQ. The consequences of sterol depletion by methyl-beta-cyclodextrin were also studied. We found that application of hydrostatic pressure led to a marked decrease of hydration as probed by F2N12S and to an increase of the generalized polarization excitation (GPex) of Laurdan. We observed that the hydration effect of sterol depletion was maximal between 1 and 1.5 kbar but was much less important at higher pressures (above 2 kbar) where both parameters reached a plateau value. The presence of a highly dehydrated gel state, insensitive to the sterol content, was thus proposed above 2.5 kbar. However, the F2N12S polarity parameter and the di-4-ANEPPDHQ intensity ratio showed strong effect on sterol depletion, even at very high pressures (2.5-3.5 kbar), and supported the ability of sterols to modify the electrostatic properties of membrane, notably its dipole potential, in a highly dehydrated gel phase. We thus suggested that BY-2 PM undergoes a complex phase behavior in response to the hydrostatic pressure and we also emphasized the role of phytosterols to regulate the effects of high hydrostatic pressure on plant PM. PMID:20381451

  14. High sensitivity detection of trace gases at atmospheric pressure using tunable diode lasers

    NASA Technical Reports Server (NTRS)

    Reid, J.; Sinclair, R. L.; Grant, W. B.; Menzies, R. T.

    1985-01-01

    A detailed study of the detection of trace gases at atmospheric pressure using tunable diode lasers is described. The influence of multipass cells, retroreflectors and topographical targets is examined. The minimum detectable infrared absorption ranges from 0.1 percent for a pathlength of 1.2 km to 0.01 percent over short pathlengths. The factors which limit this sensitivity are discussed, and the techniques are illustrated by monitoring atmospehric CO2 and CH4.

  15. Interpretation of Helioseismic Travel Times. Sensitivity to Sound Speed, Pressure, Density, and Flows

    NASA Astrophysics Data System (ADS)

    Burston, Raymond; Gizon, Laurent; Birch, Aaron C.

    2015-12-01

    Time-distance helioseismology uses cross-covariances of wave motions on the solar surface to determine the travel times of wave packets moving from one surface location to another. We review the methodology to interpret travel-time measurements in terms of small, localised perturbations to a horizontally homogeneous reference solar model. Using the first Born approximation, we derive and compute 3D travel-time sensitivity (Fréchet) kernels for perturbations in sound-speed, density, pressure, and vector flows. While kernels for sound speed and flows had been computed previously, here we extend the calculation to kernels for density and pressure, hence providing a complete description of the effects of solar dynamics and structure on travel times. We treat three thermodynamic quantities as independent and do not assume hydrostatic equilibrium. We present a convenient approach to computing damped Green's functions using a normal-mode summation. The Green's function must be computed on a wavenumber grid that has sufficient resolution to resolve the longest lived modes. The typical kernel calculations used in this paper are computer intensive and require on the order of 600 CPU hours per kernel. Kernels are validated by computing the travel-time perturbation that results from horizontally-invariant perturbations using two independent approaches. At fixed sound-speed, the density and pressure kernels are approximately related through a negative multiplicative factor, therefore implying that perturbations in density and pressure are difficult to disentangle. Mean travel-times are not only sensitive to sound-speed, density and pressure perturbations, but also to flows, especially vertical flows. Accurate sensitivity kernels are needed to interpret complex flow patterns such as convection.

  16. Variants in Striatin Gene are Associated with Salt Sensitive Blood Pressure in Mice and Humans

    PubMed Central

    Sun, Bei; Williams, Jonathan; Lasky-Su, Jessica; Baudrand, Rene; Yao, Tham; Moize, Burhanuddin; Hafiz, Wan M; Romero, Jose R.; Adler, Gail K.; Ferri, Claudio; Hopkins, Paul N.; Pojoga, Luminita H.; Williams, Gordon H.

    2015-01-01

    Striatin is a novel protein that interacts with steroid receptors and modifies rapid, non-genomic activity in vitro. We tested the hypothesis that striatin would in turn affect mineralocorticoid receptor function and consequently sodium, water, and blood pressure homeostasis in an animal model. We evaluated salt sensitivity of blood pressure in novel striatin heterozygote knockout mice. When compared with wild type, striatin heterozygote exhibited a significant increase in blood pressure when sodium intake was increased from restricted (0.03%) to liberal (1.6%) sodium). Further, renal expression of mineralocorticoid receptor and its genomic downstream targets serum/glucocoticoid-regulated kinase 1 and epithelial sodium channel were increased in striatin heterozygote versus wild type mice on liberal sodium intake while the pAkt/Akt ratio, readout of mineralocoriticoid receptor's rapid, non-genomic pathway, was reduced. To determine the potential clinical relevance of these findings, we tested the association between single nucleotide polymorphic variants of striatin gene and salt sensitivity of blood presure in 366 Caucasian hypertensive subjects. HapMap derived tagging single nucleotide polymorphisms identified an association between rs2540923 with salt sensitivity of blood pressure (OR, 6.25; 95% CI 1.7-20; P=0.01). These data provide the first in vivo evidence in humans and rodents that associates striatin with markers of mineralocoriticoid receptor activity. The data also support the hypothesis that the rapid, non-genomic mineralocoriticoid receptor pathway (mediated via striatin) has a role in modulating the interaction between salt intake and blood pressure. PMID:25368024

  17. Single-shot temperature- and pressure-sensitive paint measurements on an unsteady helicopter blade

    NASA Astrophysics Data System (ADS)

    Disotell, Kevin J.; Peng, Di; Juliano, Thomas J.; Gregory, James W.; Crafton, Jim W.; Komerath, Narayanan M.

    2014-02-01

    Unsteady pressure-sensitive paint (PSP) measurements were acquired on an articulated model helicopter rotor of 0.26 m diameter in edgewise flow to simulate forward flight conditions. The rotor was operated at advance ratios (free stream velocity normalized by hover tip speed) of 0.15 and 0.30 at a cycle-averaged tip chord Reynolds number of 1.1 × 105, with collective and longitudinal cyclic pitch inputs of 10° and 2.5°, respectively. A single-shot data acquisition technique allowed a camera to record the paint luminescence after a single pulse of high-energy laser excitation, yielding sufficient signal-to-noise ratio to avoid image averaging. Platinum tetra(pentafluorophenyl) porphyrin (PtTFPP) in a porous polymer/ceramic binder served as the PSP. To address errors caused by image blurring and temperature sensitivity, a previously reported motion deblurring algorithm was implemented and the temperature correction was made using temperature-sensitive paint measurements on a second rotor blade. Instantaneous, unsteady surface pressure maps at a rotation rate of 82 Hz captured different aerodynamic responses between the two sides of the rotor disk and were compared to the nominally steady hover case. Cycle-to-cycle variations in tip unsteadiness on the retreating blade were also observed, causing oblique pressure features which may be linked to three-dimensional stall.

  18. Luminophore Application Study of Polymer-Ceramic Pressure-Sensitive Paint

    PubMed Central

    Sakaue, Hirotaka; Hayashi, Tatsunori; Ishikawa, Hitoshi

    2013-01-01

    A polymer-ceramic pressure-sensitive paint (PC-PSP) is a fast responding and sprayable PSP which has been applied for capturing global unsteady flows. The luminophore application process is studied to enhance the characterization of the PC-PSP. A dipping deposition method is used to apply a luminophore on a polymer-ceramic coating. The method selects a solvent by its polarity index. The characterization includes the signal level, pressure sensitivity, temperature dependency, and response time. It is found that the luminophore application process affects the steady-state characterizations, such as the signal level, pressure sensitivity, and temperature dependency. A range of change for each characterization, which is based on the minimum quantity, is a factor of 4.7, 9, and 3.8, respectively. A response time on the order of ten microseconds is shown. The application process is not a dominant factor for changing the response time, which is within the uncertainty of the thickness variation. Comparisons of the effects on the luminophore application process and the polymer content are made to discuss the PC-PSP characterization results. PMID:23760088

  19. Dielectric resonator-based resonant structure for sensitive ESR measurements at high-hydrostatic pressures.

    PubMed

    Sienkiewicz, Andrzej; Vileno, Bertrand; Garaj, Slaven; Jaworski, Marek; Forró, László

    2005-12-01

    We present a newly developed microwave probe head that accommodates a gasketed sapphire anvil cell (SAC) for performing sensitive electron spin resonance (ESR) measurements under high-hydrostatic pressures. The system was designed around commercially available dielectric resonators (DRs) having the dielectric permittivity of approximately 30. The microwave resonant structure operates in a wide-stretched double-stacked geometry and resonates in the lowest cylindrical quasi TE(011) mode around 9.2 GHz. The most vital parts of the probe's microwave heart were made of plastic materials, thus making the resonant structure transparent to magnetic field modulation at 100 kHz. The overall ESR sensitivity of the probe was demonstrated for a small speck of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) positioned in the gasket of the SAC, using water as the pressure-transmitting medium. The system was also used for studying pressure-induced changes in spin-relaxation mechanisms of a quasi-1D-conducting polymer, K(1)C(60). For small samples located in the sample hole of the gasket the probe reveals sensitivity that is only approximately 3 times less than that yielded by regular ESR cavities. PMID:16168687

  20. A new type of functional chemical sensitizer MgH2 for improving pressure desensitization resistance of emulsion explosives

    NASA Astrophysics Data System (ADS)

    Cheng, Y. F.; Yan, S. L.; Ma, H. H.; Shen, Z. W.; Liu, R.

    2016-03-01

    In millisecond-delay blasting and deep water blasting projects, traditional emulsion explosives sensitized by the chemical sensitizer NaNO2 often encounter incomplete explosion or misfire problems because of the "pressure desensitization" phenomenon, which seriously affects blasting safety and construction progress. A MgH2-sensitized emulsion explosive was invented to solve these problems. Experimental results show that MgH2 can effectively reduce the problem of pressure desensitization. In this paper, the factors which influence the pressure desensitization of two types of emulsion explosives are studied, and resistance to this phenomenon of MgH2-sensitized emulsion explosives is discussed.

  1. Improving Liquid Chromatography-Mass Spectrometry Sensitivity Using a Subambient Pressure Ionization with Nanoelectrospray (SPIN) Interface

    PubMed Central

    Tang, Keqi; Page, Jason S.; Marginean, Ioan; Kelly, Ryan T.; Smith, Richard D.

    2011-01-01

    In this work, the subambient pressure ionization with nanoelectrospray (SPIN) ion source and interface, which operates at ~15–30 Torr, is demonstrated to be compatible with gradient reversed-phase liquid chromatography-MS applications, exemplified here with the analysis of complex samples (a protein tryptic digest and a whole cell lysate). A low liquid chromatographic flow rate (100–400 nL/min) allowed stable electrospray to be established while avoiding electrical breakdown. Efforts to increase the operating pressure of the SPIN source relative to previously reported designs prevented solvent freezing and enhanced charged cluster/droplet desolvation. A 5- to 12-fold improvement in sensitivity relative to a conventional atmospheric pressure nanoelectrospray ionization (ESI) source was obtained for detected peptides. PMID:21953185

  2. Controlled Adhesion of Silicone Elastomer Surfaces

    NASA Astrophysics Data System (ADS)

    Owen, Michael

    2000-03-01

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

  3. Application of Pressure Sensitive Paint to Confined Flow at Mach Number 2.5

    NASA Technical Reports Server (NTRS)

    Lepicovsky, J.; Bencic, T. J.; Bruckner, R. J.

    1998-01-01

    Pressure sensitive paint (PSP) is a novel technology that is being used frequently in external aerodynamics. For internal flows in narrow channels, and applications at elevated nonuniform temperatures, however, there are still unresolved problems that complicate the procedures for calibrating PSP signals. To address some of these problems, investigations were carried out in a narrow channel with supersonic flows of Mach 2.5. The first set of tests focused on the distribution of the wall pressure in the diverging section of the test channel downstream of the nozzle throat. The second set dealt with the distribution of wall static pressure due to the shock/wall interaction caused by a 25 deg. wedge in the constant Mach number part of the test section. In addition, the total temperature of the flow was varied to assess the effects of temperature on the PSP signal. Finally, contamination of the pressure field data, caused by internal reflection of the PSP signal in a narrow channel, was demonstrated. The local wall pressures were measured with static taps, and the wall pressure distributions were acquired by using PSP. The PSP results gave excellent qualitative impressions of the pressure field investigated. However, the quantitative results, specifically the accuracy of the PSP data in narrow channels, show that improvements need to be made in the calibration procedures, particularly for heated flows. In the cases investigated, the experimental error had a standard deviation of +/- 8.0% for the unheated flow, and +/- 16.0% for the heated flow, at an average pressure of 11 kpa.

  4. The blood pressure-salt sensitivity paradigm: pathophysiologically sound yet of no practical value.

    PubMed

    Galletti, Ferruccio; Strazzullo, Pasquale

    2016-09-01

    Sodium plays an important pathophysiological role in blood pressure (BP) values and in the development of hypertension, and epidemiological studies such as the Intersalt Study have shown that the increase in BP occurring with age is determined by salt intake. Recently, a meta-analysis of 13 prospective studies has also shown the close relationship between excess sodium intake and higher risk of stroke and total cardiovascular events. However, the BP response to changing salt intake displayed a marked variability, as first suggested by Kawasaki et al. (The effect of high-sodium and low-sodium intakes on blood pressure and other related variables in human subjects with idiopathic hypertension. Am J Med 1978; 64: 193-198) and later by Weinberger et al. (Definitions and characteristics of sodium sensitivity and blood pressure resistance. Hypertension 1986; 8: II127-II134), who recognized the heterogeneity of the BP response to salt and developed the concept of salt sensitivity. We have a large body of evidence in favour of a major role of metabolic and neuro-hormonal factors in determining BP salt sensitivity in association with the effect of genetic variation. There is evidence that salt sensitivity influences the development of organ damage, even independently-at least in part-of BP levels and the occurrence of hypertension. In addition, several observational studies indicate that salt sensitivity is clearly associated with a higher rate of cardiovascular events and mortality, independently of BP levels and hypertension. A cluster of factors with well-known atherogenic potential such as hyperinsulinaemia, dyslipidaemia and microalbuminuria-all known to be prevalent in salt-sensitive hypertension-might at least partially explain the increased cardiovascular risk observed in salt sensitive individuals. The gold standard for the evaluation of BP salt sensitivity is the BP response to a moderate reduction of salt intake for several weeks; nevertheless, these protocols

  5. Responsiveness vs. basal activity of plasma ANG II as a determinant of arterial pressure salt sensitivity.

    PubMed

    Osborn, John W; Ariza-Nieto, Pilar; Collister, John P; Soucheray, Sandra; Zimmerman, Benjamin; Katz, Stephen

    2003-11-01

    Infusion of angiotensin II (ANG II) causes salt-sensitive hypertension. It is unclear whether this is due to the body's inability to suppress ANG II during increased salt intake or, rather, an elevated basal level of plasma ANG II itself. To distinguish between these mechanisms, Sprague-Dawley rats were instrumented with arterial and venous catheters for measurement of arterial pressure and infusion of drugs, respectively. The sensitivity of arterial pressure to salt was measured in four groups with the following treatments: 1) saline control (Con, n = 12); 2) administration of the angiotensin-converting enzyme inhibitor enalapril to block endogenous ANG II (ANG-Lo, n = 10); 3) administration of enalapril and 5 ng.kg(-1).min(-1) ANG II to clamp plasma ANG II at normal levels (ANG-Norm, n = 10); and 4) administration of enalapril and 20 ng.kg(-1).min(-1) ANG II to clamp ANG II at high levels (ANG-Hi, n = 10). Rats ingested a 0.4% NaCl diet for 3 days and then a 4.0% NaCl diet for 11 days. Arterial pressure of rats fed the 0.4% NaCl diet was lower in ANG-Lo (84 +/- 2 mmHg) compared with Con (101 +/- 3 mmHg) and ANG-Norm (98 +/- 4 mmHg) groups, whereas ANG-Hi rats were hypertensive (145 +/- 4 mmHg). Salt sensitivity was expressed as the change in arterial pressure divided by the change in sodium intake on the last day of the 4.0% NaCl diet. Salt sensitivity (in mmHg/meq Na) was lowest in Con rats (0.0 +/- 0.1) and progressed from ANG-Lo (0.8 +/- 0.2) to ANG-Norm (1.5 +/- 0.5) to ANG-Hi (3.5 +/- 0.5) rats. We conclude that the major determinant of salt sensitivity of arterial pressure is the basal level of plasma ANG II rather than the responsiveness of the renin-angiotensin system. PMID:12881218

  6. Application of Pressure-Sensitive Paint to Ice-Accreted Wind Tunnel Models

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy J.

    2000-01-01

    Pressure-sensitive paint (PSP) has been successfully used to measure global surface pressures on an ice-accreted model in an icing wind tunnel at NASA Glenn Research Center. Until now, the PSP technique has been limited to use in normal wind tunnels and clear flight environments. This is the first known application of PSP directly to ice in subfreezing conditions. Several major objectives were achieved in these tests. The procedure for applying the coating in the subfreezing tunnel environment was verified. Inspection of the painted ice surface revealed that the paint did not alter the original ice shape and adhered well over the entire coated area. Several procedures were used to show that the paint responded to changes in air pressure and that a repeatable pressure-dependent calibration could be achieved on the PSP-coated surfaces. Differences in pressure measurements made simultaneously on the ice and the metal test model are not yet fully understood, and techniques to minimize or correct them are being investigated.

  7. High-sensitivity NMR beyond 200,000 atmospheres of pressure

    NASA Astrophysics Data System (ADS)

    Meier, T.; Reichardt, S.; Haase, J.

    2015-08-01

    Pressure-induced changes in the chemical or electronic structure of solids require pressures well into the Giga-Pascal (GPa) range due to the strong bonding. Anvil cell designs can reach such pressures, but their small and mostly inaccessible sample chamber has severely hampered NMR experiments in the past. With a new cell design that has a radio frequency (RF) micro-coil in the high pressure chamber, NMR experiments beyond 20 Giga-Pascal are reported for the first time. 1 H NMR of water shows sensitivity and resolution obtained with the cells, and 63 Cu NMR on a cuprate superconductor (YBa2Cu3O7-δ) demonstrates that single-crystals can be investigated, as well. 115 In NMR of the ternary chalcogenide AgInTe2 discovers an insulator-metal transition with shift and relaxation measurements. The pressure cells can be mounted easily on standard NMR probes that fit commercial wide-bore magnets with regular cryostats for field- and temperature-dependent measurements ready for many applications in physics and chemistry.

  8. Salt sensitivity of blood pressure is associated with polymorphisms in the sodium-bicarbonate cotransporter.

    PubMed

    Carey, Robert M; Schoeffel, Cynthia D; Gildea, John J; Jones, John E; McGrath, Helen E; Gordon, Lindsay N; Park, Min Jeong; Sobota, Rafal S; Underwood, Patricia C; Williams, Jonathan; Sun, Bei; Raby, Benjamin; Lasky-Su, Jessica; Hopkins, Paul N; Adler, Gail K; Williams, Scott M; Jose, Pedro A; Felder, Robin A

    2012-11-01

    Previous studies have demonstrated that single nucleotide polymorphisms (SNPs) of the sodium-bicarbonate co-transporter gene (SLC4A5) are associated with hypertension. We tested the hypothesis that SNPs in SLC4A5 are associated with salt sensitivity of blood pressure in 185 whites consuming an isocaloric constant diet with a randomized order of 7 days of low Na(+) (10 mmol/d) and 7 days of high Na(+) (300 mmol/d) intake. Salt sensitivity was defined as a ≥ 7-mm Hg increase in mean arterial pressure during a randomized transition between high and low Na(+) diet. A total of 35 polymorphisms in 17 candidate genes were assayed, 25 of which were tested for association. Association analyses with salt sensitivity revealed 3 variants that associated with salt sensitivity, 2 in SLC4A5 (P<0.001) and 1 in GRK4 (P=0.020). Of these, 2 SNPs in SLC4A5 (rs7571842 and rs10177833) demonstrated highly significant results and large effects sizes, using logistic regression. These 2 SNPs had P values of 1.0 × 10(-4) and 3.1 × 10(-4) with odds ratios of 0.221 and 0.221 in unadjusted regression models, respectively, with the G allele at both sites conferring protection. These SNPs remained significant after adjusting for body mass index and age (P=8.9 × 10(-5) and 2.6 × 10(-4) and odds ratios 0.210 and 0.286, respectively). Furthermore, the association of these SNPs with salt sensitivity was replicated in a second hypertensive population. Meta-analysis demonstrated significant associations of both SNPs with salt sensitivity (rs7571842 [P=1.2 × 10(-5)]; rs1017783 [P=1.1 × 10(-4)]). In conclusion, SLC4A5 variants are strongly associated with salt sensitivity of blood pressure in 2 separate white populations. PMID:22987918

  9. A wearable and highly sensitive pressure sensor with ultrathin gold nanowires

    NASA Astrophysics Data System (ADS)

    Gong, Shu; Schwalb, Willem; Wang, Yongwei; Chen, Yi; Tang, Yue; Si, Jye; Shirinzadeh, Bijan; Cheng, Wenlong

    2014-02-01

    Ultrathin gold nanowires are mechanically flexible yet robust, which are novel building blocks with potential applications in future wearable optoelectronic devices. Here we report an efficient, low-cost fabrication strategy to construct a highly sensitive, flexible pressure sensor by sandwiching ultrathin gold nanowire-impregnated tissue paper between two thin polydimethylsiloxane sheets. The entire device fabrication process is scalable, enabling facile large-area integration and patterning for mapping spatial pressure distribution. Our gold nanowires-based pressure sensors can be operated at a battery voltage of 1.5 V with low energy consumption (<30 μW), and are able to detect pressing forces as low as 13 Pa with fast response time (<17 ms), high sensitivity (>1.14 kPa-1) and high stability (>50,000 loading-unloading cycles). In addition, our sensor can resolve pressing, bending, torsional forces and acoustic vibrations. The superior sensing properties in conjunction with mechanical flexibility and robustness enabled real-time monitoring of blood pulses as well as detection of small vibration forces from music.

  10. Flexible polymer transistors with high pressure sensitivity for application in electronic skin and health monitoring

    NASA Astrophysics Data System (ADS)

    Schwartz, Gregor; Tee, Benjamin C.-K.; Mei, Jianguo; Appleton, Anthony L.; Kim, Do Hwan; Wang, Huiliang; Bao, Zhenan

    2013-05-01

    Flexible pressure sensors are essential parts of an electronic skin to allow future biomedical prostheses and robots to naturally interact with humans and the environment. Mobile biomonitoring in long-term medical diagnostics is another attractive application for these sensors. Here we report the fabrication of flexible pressure-sensitive organic thin film transistors with a maximum sensitivity of 8.4 kPa-1, a fast response time of <10 ms, high stability over >15,000 cycles and a low power consumption of <1 mW. The combination of a microstructured polydimethylsiloxane dielectric and the high-mobility semiconducting polyisoindigobithiophene-siloxane in a monolithic transistor design enabled us to operate the devices in the subthreshold regime, where the capacitance change upon compression of the dielectric is strongly amplified. We demonstrate that our sensors can be used for non-invasive, high fidelity, continuous radial artery pulse wave monitoring, which may lead to the use of flexible pressure sensors in mobile health monitoring and remote diagnostics in cardiovascular medicine.

  11. Vibration Sensitivity of a Wide-Temperature Electronically Scanned Pressure Measurement (ESP) Module

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J.; Garza, Frederico R.

    2001-01-01

    A vibration sensitivity test was conducted on a Wide-Temperature ESP module. The test object was Module "M4," a 16-channel, 4 psi unit scheduled for installation in the Arc Sector of NTF. The module was installed on a vibration exciter and loaded to positive then negative full-scale pressures (+/-2.5 psid). Test variables were the following: Vibration frequencies: 20, 55, 75 Hz. Vibration level: 1 g. Vibration axes: X, Y, Z. The pressure response was measured on each channel, first without and then with the vibration turned on, and the difference analyzed by means of the statistical t-test. The results show that the vibration sensitivity does not exceed 0.01% Full Scale Output per g (with the exception of one channel on one axis) to a 95 percent confidence level. This specification, limited by the resolution of the pressure source, lies well below the total uncertainty specification of 0.1 percent Full Scale Output.

  12. Elevated intraocular pressure decreases response sensitivity of inner retinal neurons in experimental glaucoma mice

    PubMed Central

    Pang, Ji-Jie; Frankfort, Benjamin J.; Gross, Ronald L.; Wu, Samuel M.

    2015-01-01

    Glaucoma is the second leading cause of blindness in the United States and the world, characterized by progressive degeneration of the optic nerve and retinal ganglion cells (RGCs). Glaucoma patients exhibit an early diffuse loss of retinal sensitivity followed by focal loss of RGCs in sectored patterns. Recent evidence has suggested that this early sensitivity loss may be associated with dysfunctions in the inner retina, but detailed cellular and synaptic mechanisms underlying such sensitivity changes are largely unknown. In this study, we use whole-cell voltage-clamp techniques to analyze light responses of individual bipolar cells (BCs), AII amacrine cells (AIIACs), and ON and sustained OFF alpha-ganglion cells (ONαGCs and sOFFαGCs) in dark-adapted mouse retinas with elevated intraocular pressure (IOP). We present evidence showing that elevated IOP suppresses the rod ON BC inputs to AIIACs, resulting in less sensitive AIIACs, which alter AIIAC inputs to ONαGCs via the AIIAC→cone ON BC→ONαGC pathway, resulting in lower ONαGC sensitivity. The altered AIIAC response also reduces sOFFαGC sensitivity via the AIIAC→sOFFαGC chemical synapses. These sensitivity decreases in αGCs and AIIACs were found in mice with elevated IOP for 3–7 wk, a stage when little RGC or optic nerve degeneration was observed. Our finding that elevated IOP alters neuronal function in the inner retina before irreversible structural damage occurs provides useful information for developing new diagnostic tools and treatments for glaucoma in human patients. PMID:25675503

  13. Oxygen sensitivity of zinc oxide nanoparticles produced via laser-ablated plasma in pressurized liquid

    NASA Astrophysics Data System (ADS)

    Goto, Taku; Shimizu, Yoshiki; Ito, Tsuyohito

    2015-09-01

    While traditional semiconductor oxygen sensor operate only with elevated temperature (= 700 K), the room-temperature operation of the ZnO oxygen sensors have been demonstrated with the help of UV light irradiation. Especially, ZnO nanotubes and nanoparticles have attracted much attentions as highly sensitive oxygen sensors and photodetectors. To the best of our knowledge, the reported works of gas sensors with ZnO nanostructures have been mostly intended for revealing effects of the morphology/shape and the size of the nanostructures. For further improvements of the ZnO-based gas sensors, it is probably required to understand effects of microscopic structures, such as densities of various defects. In this study, we synthesized the ZnO nanoparticles with various defects by means of laser-ablated plasma in pressurized water-ethanol mixture. The results indicate that the defects in ZnO affect oxygen sensitivity, and especially VO + defects seem to be mostly responsible for the resistance change of ZnO nanoparticles. We demonstrate that partial oxygen pressure can be measured with high sensitivity.

  14. High Sensitivity Combined with Extended Structural Coverage of Labile Compounds via Nanoelectrospray Ionization at Subambient Pressures

    SciTech Connect

    Cox, Jonathan T.; Kronewitter, Scott R.; Shukla, Anil K.; Moore, Ronald J.; Smith, Richard D.; Tang, Keqi

    2014-10-07

    Subambient pressure ionization with nanoelectrospray (SPIN) has proven to be effective in producing ions with high efficiency and transmitting them to low pressures for high sensitivity mass spectrometry (MS) analysis. Here we present evidence that not only does the SPIN source improve MS sensitivity but also allows for gentler ionization conditions. The gentleness of a conventional heated capillary electrospray ionization (ESI) source and the SPIN source was compared by the liquid chromatography mass spectrometry (LC-MS) analysis of colominic acid. Colominic acid is a mixture of sialic acid polymers of different lengths containing labile glycosidic linkages between monomer units necessitating a gentle ion source. By coupling the SPIN source with high resolution mass spectrometry and using advanced data processing tools, we demonstrate much extended coverage of sialic acid polymer chains as compared to using the conventional ESI source. Additionally we show that SPIN-LC-MS is effective in elucidating polymer features with high efficiency and high sensitivity previously unattainable by the conventional ESI-LC-MS methods.

  15. High Perfusion Pressure Accelerates Renal Injury in Salt-Sensitive Hypertension

    PubMed Central

    Mori, Takefumi; Polichnowski, Aaron; Glocka, Padden; Kaldunski, Mary; Ohsaki, Yusuke; Liang, Mingyu; Cowley, Allen W.

    2008-01-01

    Renal injury in the Dahl salt-sensitive rat mimics human salt-sensitive forms of hypertension that are particularly prevalent in black individuals, but the mechanisms that lead to the development of this injury are incompletely understood. We studied the impact of renal perfusion pressure (RPP) on the development of renal injury in this model. During the development of salt-induced hypertension over 2 wk, the RPP to the left kidney was maintained at control levels (125 ± 2 mmHg) by continuous servocontrol inflation of an aortic balloon implanted between the renal arteries; during the same period, the RPP to the right kidney rose to 164 ± 8 mmHg. After 2 wk of a 4% salt diet, DNA microarray and real-time PCR identified genes related to fibrosis and epithelial-to-mesenchymal transition in the kidneys exposed to hypertension. The increased RPP to the right kidney accounted for differences in renal injury between the two kidneys, measured by percentage of injured cortical and juxtamedullary glomeruli, quantified proteinaceous casts, number of ED-1–positive cells per glomerular tuft area, and interstitial fibrosis. Interlobular arteriolar injury was not increased in the kidney exposed to elevated pressure but was reduced in the control kidney. We conclude that elevations of RPP contribute significantly to the fibrosis and epithelial-to-mesenchymal transition found in the early phases of hypertension in the salt-sensitive rat. PMID:18417720

  16. Effects of dynamic shear and transmural pressure on wall shear stress sensitivity in collecting lymphatic vessels.

    PubMed

    Kornuta, Jeffrey A; Nepiyushchikh, Zhanna; Gasheva, Olga Y; Mukherjee, Anish; Zawieja, David C; Dixon, J Brandon

    2015-11-01

    Given the known mechanosensitivity of the lymphatic vasculature, we sought to investigate the effects of dynamic wall shear stress (WSS) on collecting lymphatic vessels while controlling for transmural pressure. Using a previously developed ex vivo lymphatic perfusion system (ELPS) capable of independently controlling both transaxial pressure gradient and average transmural pressure on an isolated lymphatic vessel, we imposed a multitude of flow conditions on rat thoracic ducts, while controlling for transmural pressure and measuring diameter changes. By gradually increasing the imposed flow through a vessel, we determined the WSS at which the vessel first shows sign of contraction inhibition, defining this point as the shear stress sensitivity of the vessel. The shear stress threshold that triggered a contractile response was significantly greater at a transmural pressure of 5 cmH2O (0.97 dyne/cm(2)) than at 3 cmH2O (0.64 dyne/cm(2)). While contraction frequency was reduced when a steady WSS was applied, this inhibition was reversed when the applied WSS oscillated, even though the mean wall shear stresses between the conditions were not significantly different. When the applied oscillatory WSS was large enough, flow itself synchronized the lymphatic contractions to the exact frequency of the applied waveform. Both transmural pressure and the rate of change of WSS have significant impacts on the contractile response of lymphatic vessels to flow. Specifically, time-varying shear stress can alter the inhibition of phasic contraction frequency and even coordinate contractions, providing evidence that dynamic shear could play an important role in the contractile function of collecting lymphatic vessels. PMID:26333787

  17. Flow Visualization at Cryogenic Conditions Using a Modified Pressure Sensitive Paint Approach

    NASA Technical Reports Server (NTRS)

    Watkins, A. Neal; Goad, William K.; Obara, Clifford J.; Sprinkle, Danny R.; Campbell, Richard L.; Carter, Melissa B.; Pendergraft, Odis C., Jr.; Bell, James H.; Ingram, JoAnne L.; Oglesby, Donald M.

    2005-01-01

    A modification to the Pressure Sensitive Paint (PSP) method was used to visualize streamlines on a Blended Wing Body (BWB) model at full-scale flight Reynolds numbers. In order to achieve these conditions, the tests were carried out in the National Transonic Facility operating under cryogenic conditions in a nitrogen environment. Oxygen is required for conventional PSP measurements, and several tests have been successfully completed in nitrogen environments by injecting small amounts (typically < 3000 ppm) of oxygen into the flow. A similar technique was employed here, except that air was purged through pressure tap orifices already existent on the model surface, resulting in changes in the PSP wherever oxygen was present. The results agree quite well with predicted results obtained through computational fluid dynamics analysis (CFD), which show this to be a viable technique for visualizing flows without resorting to more invasive procedures such as oil flow or minitufts.

  18. The Development and Implementation of a Cryogenic Pressure Sensitive Paint System in the National Transonic Facility

    NASA Technical Reports Server (NTRS)

    Watkins, A. Neal; Leighty, Bradley D.; Lipford, William E.; Oglesby, Donald M.; Goodman, Kyle Z.; Goad, William K.; Goad, Linda R.; Massey, Edward A.

    2009-01-01

    The Pressure Sensitive Paint (PSP) method was used to measure global surface pressures on a model at full-scale flight Reynolds numbers. In order to achieve these conditions, the test was carried out at the National Transonic Facility (NTF) operating under cryogenic conditions in a nitrogen environment. The upper surface of a wing on a full-span 0.027 scale commercial transport was painted with a porous PSP formulation and tested at 120K. Data was acquired at Mach 0.8 with a total pressure of 200 kPa, resulting in a Reynolds number of 65 x 106/m. Oxygen, which is required for PSP operation, was injected using dry air so that the oxygen concentration in the flow was approximately 1535 ppm. Results show qualitative agreement with expected results. This preliminary test is the first time that PSP has been successfully deployed to measure global surface pressures at cryogenic condition in the NTF. This paper will describe the system as installed, the results obtained from the test, as well as proposed upgrades and future tests.

  19. Measuring Spatial and Temporal Heterogeneity of Dissolved Oxygen in Streambed Sediments Using Pressure Sensitive Paint (PSP)

    NASA Astrophysics Data System (ADS)

    Huynh, K. T.; Salus, A.; Xie, M.; Roche, K. R.; Packman, A. I.

    2014-12-01

    Pressure sensitive paints (PSP) have been largely used in aerodynamic applications to measure pressure distributions on complex bodies such as aircraft. One common family of PSPs employ fluorescent pigments that are quenched in the presence of oxygen, yielding an inverse relationship between fluorescence intensity and oxygen concentration that is used to measure pressure in aerodynamic applications through the partial pressure of oxygen. These PSPs offer unexplored potential for visualizing dissolved oxygen (DO) concentration distributions on surfaces underwater. PSP was used to measure dissolved oxygen concentrations in streambed sediments in a laboratory flume. Two PSP-coated 2.5 cm diameter spheres were emplaced in a bed of similar material, and imaged under varying DO concentrations. Calibration curves relating fluorescence intensity to dissolved oxygen concentration were developed on a pixel-by-pixel basis, enabling spatial patterns of oxygen to be resolved in the sediment bed. This method of measuring dissolved oxygen concentration is advantageous because of its fast response time and ability to measure heterogeneous oxygen distributions in sediments. Future work will explore the combined effects of stream flow and biofilm growth on oxygen distributions in streambed sediments.

  20. Investigation of impinging jet resonant modes using unsteady pressure-sensitive paint measurements

    NASA Astrophysics Data System (ADS)

    Davis, Timothy; Edstrand, Adam; Alvi, Farrukh; Cattafesta, Louis; Yorita, Daisuke; Asai, Keisuke

    2015-05-01

    At given nozzle to plate spacings, the flow field of high-speed impinging jets is known to be characterized by a resonance phenomenon. Large coherent structures that convect downstream and impinge on the surface create strong acoustic waves that interact with the inherently unstable shear layer at the nozzle exit. This feedback mechanism, driven by the coherent structures in the jet shear layer, can either be axisymmetric or helical in nature. Fast-response pressure-sensitive paint (PSP) is applied to the impingement surface to map the unsteady pressure distribution associated with these resonant modes. Phase-averaged results acquired at several kHz are obtained using a flush mounted unsteady pressure transducer on the impingement plate as a reference signal. Tests are conducted on a Mach 1.5 jet at nozzle to plate spacings of . The resulting phase-averaged distribution reveals dramatically different flow fields at the corresponding impingement heights. The existence of a purely axisymmetric mode with a frequency of 6.3 kHz is identified at and is characterized by concentric rings of higher/lower pressure that propagate radially with increasing phase. Two simultaneous modes are observed at with one being a dominant symmetric mode at 7.1 kHz and the second a sub-dominant helical mode at 4.3 kHz. Complimentary phase-conditioned Schlieren images are also obtained visualizing the flow structures associated with each mode and are consistent with the PSP results.

  1. Atmospheric pressure glow discharge deposition of thermo-sensitive poly (N-isopropylacrylamide)

    NASA Astrophysics Data System (ADS)

    Shao, M.; Tang, X. L.; Wen, D.; Chen, Y.; Qiu, G.

    2013-12-01

    In this paper, a self-made atmospheric pressure dielectric barrier discharge reactor on intermediate frequency is brought forward and developed, which is equipped with power supply of 1-20 KHz, and the working gas is argon. The experimental results show that is a very stable and uniform atmospheric pressure glow discharge (APGD). Through a series of experiments, the waveforms of single pulse and multi-pulse glow discharge were both obtained. The voltage amplitude, discharge gap and dielectric material are studied, and the conditions of multi-pulse glow discharge are discussed as well. The novel methods of depositing poly (N-isopropylacrylamide) (PNIPAAm) coatings on the surface of glass slides and PS petri dish are provided by atmospheric pressure plasma polymerization. PNIPAAm can be obtained by plasma polymerization of N-isopropylacrylamide using the self-made equipment of atmospheric pressure plasma vapor treatment. The samples were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle. SEM analysis has revealed that the PNIPAAm coatings were formed on the surface of the smooth glass slides. Further evaluation by using XPS, it has shown the presence of PNIPAAm. The wettability can be significantly modified by changing of the temperatures at above and below of the lower critical solution temperature (LCST) from the data of the contact angle test. These results have advantage for further application on the thermo-sensitive textile materials.

  2. A perturbation solution for transverse pressure-sensitive combustion instability in an annulus

    NASA Technical Reports Server (NTRS)

    Googerdy, A.; Peddieson, J., Jr.

    1980-01-01

    A method for analysis of combustion instability in rocket motors based on a combination of the Galerkin method and the two-variable (or multiple-scales) perturbation method is developed. The method is illustrated by applying it to the problem of pressure-sensitive combustion instability in a liquid-fuel annular combustion chamber. To the order of approximation inherent in the method it is found that the complete linear stability analysis and most of the nonlinear stability analysis can be carried out in closed form. The results thus obtained are used to clarify several aspects of the interpretation of numerical solutions obtained by previous investigators.

  3. Sensitivity of CO2 migration estimation on reservoir temperature and pressure uncertainty

    SciTech Connect

    Jordan, Preston; Doughty, Christine

    2008-11-01

    The density and viscosity of supercritical CO{sub 2} are sensitive to pressure and temperature (PT) while the viscosity of brine is sensitive primarily to temperature. Oil field PT data in the vicinity of WESTCARB's Phase III injection pilot test site in the southern San Joaquin Valley, California, show a range of PT values, indicating either PT uncertainty or variability. Numerical simulation results across the range of likely PT indicate brine viscosity variation causes virtually no difference in plume evolution and final size, but CO{sub 2} density variation causes a large difference. Relative ultimate plume size is almost directly proportional to the relative difference in brine and CO{sub 2} density (buoyancy flow). The majority of the difference in plume size occurs during and shortly after the cessation of injection.

  4. Design of long period fiber grating with optimal sensitivity for detecting adhesion of nano-layer on the fiber surface

    NASA Astrophysics Data System (ADS)

    Biswas, Palas; Dey, Tanoy Kumar; Basumallick, Nandini; Sinha, Prasanta Kumar; Dasgupta, Kamal; Bandyopadhyay, Somnath

    2014-05-01

    For detecting bio-molecular interaction using long period grating (LPG) we believe that a quantitative data concerning sensitivity for addition of layers on the surface and subsequently to optimize the same appears to be more usefull than defining LPG sensitivity for a surrounding refractive index change in bulk form. For the first time, to the best of our knowledge, we quantify the shift of resonant wavelength (Δλres) of the mode of interest around the transition point as a function of unit bi-layer thickness (Δd) of poly-electrolyte, deposited by ionic self assembly, and subsequently optimize the sensitivity Δλres/Δd. Experimental result show that a shift of ~12.5 nm/bi-layer is possible with optimum number of bi-layer deposition.

  5. Abnormal Pressure Pain, Touch Sensitivity, Proprioception, and Manual Dexterity in Children with Autism Spectrum Disorders

    PubMed Central

    Riquelme, Inmaculada; Hatem, Samar M.

    2016-01-01

    Children with autism spectrum disorders (ASD) often display an abnormal reactivity to tactile stimuli, altered pain perception, and lower motor skills than healthy children. Nevertheless, these motor and sensory deficits have been mostly assessed by using clinical observation and self-report questionnaires. The present study aims to explore somatosensory and motor function in children with ASD by using standardized and objective testing procedures. Methods. Tactile and pressure pain thresholds in hands and lips, stereognosis, proprioception, and fine motor performance of the upper limbs were assessed in high-functioning children with ASD (n = 27) and compared with typically developing peers (n = 30).  Results. Children with ASD showed increased pain sensitivity, increased touch sensitivity in C-tactile afferents innervated areas, and diminished fine motor performance and proprioception compared to healthy children. No group differences were observed for stereognosis. Conclusion. Increased pain sensitivity and increased touch sensitivity in areas classically related to affective touch (C-tactile afferents innervated areas) may explain typical avoiding behaviors associated with hypersensitivity. Both sensory and motor impairments should be assessed and treated in children with ASD. PMID:26881091

  6. Legato: Personal Computer Software for Analyzing Pressure-Sensitive Paint Data

    NASA Technical Reports Server (NTRS)

    Schairer, Edward T.

    2001-01-01

    'Legato' is personal computer software for analyzing radiometric pressure-sensitive paint (PSP) data. The software is written in the C programming language and executes under Windows 95/98/NT operating systems. It includes all operations normally required to convert pressure-paint image intensities to normalized pressure distributions mapped to physical coordinates of the test article. The program can analyze data from both single- and bi-luminophore paints and provides for both in situ and a priori paint calibration. In addition, there are functions for determining paint calibration coefficients from calibration-chamber data. The software is designed as a self-contained, interactive research tool that requires as input only the bare minimum of information needed to accomplish each function, e.g., images, model geometry, and paint calibration coefficients (for a priori calibration) or pressure-tap data (for in situ calibration). The program includes functions that can be used to generate needed model geometry files for simple model geometries (e.g., airfoils, trapezoidal wings, rotor blades) based on the model planform and airfoil section. All data files except images are in ASCII format and thus are easily created, read, and edited. The program does not use database files. This simplifies setup but makes the program inappropriate for analyzing massive amounts of data from production wind tunnels. Program output consists of Cartesian plots, false-colored real and virtual images, pressure distributions mapped to the surface of the model, assorted ASCII data files, and a text file of tabulated results. Graphical output is displayed on the computer screen and can be saved as publication-quality (PostScript) files.

  7. Abdominal Adhesions

    MedlinePlus

    ... Abdominal Adhesions 1 Ward BC, Panitch A. Abdominal adhesions: current and novel therapies. Journal of Surgical Research. 2011;165(1):91– ... are abdominal adhesions and intestinal obstructions ... generally do not require treatment. Surgery is the only way to treat abdominal ...

  8. High-sensitivity cryogenic temperature sensors using pressurized fiber Bragg gratings

    NASA Technical Reports Server (NTRS)

    Wu, Meng-Chou; DeHaven, Stanton L.

    2006-01-01

    Cryogenic temperature sensing was studied using a pressurized fiber Bragg grating (PFBG). The PFBG was obtained by simply applying a small diametric load to a regular fiber Bragg grating (FBG), which was coated with polyimide of a thickness of 11 micrometers. The Bragg wavelength of the PFBG was measured at temperatures from 295 to 4.2 K. A pressure-induced transition occurred at 200 K during the cooling cycle. As a result the temperature sensitivity of the PFBG was found to be nonlinear but reach 24 pm/K below 200 K, more than three times the regular FBG. For the temperature change from 80 K to 10 K, the PFBG has a total Bragg wavelength shift of about 470 pm, 10 times more than the regular FBG. From room temperature to liquid helium temperature the PFBG gives a total wavelength shift of 3.78 nm, compared to the FBG of 1.51 nm. The effect of the coating thickness on the temperature sensitivity of the gratings is also discussed.

  9. High-sensitivity Cryogenic Temperature Sensors using Pressurized Fiber Bragg Gratings

    NASA Technical Reports Server (NTRS)

    Wu, Meng-Chou; DeHaven, Stanton L.

    2006-01-01

    Cryogenic temperature sensing was studied using a pressurized fiber Bragg grating (PFBG). The PFBG was obtained by simply applying a small diametric load to a regular fiber Bragg grating (FBG), which was coated with polyimide of a thickness of 11 micrometers. The Bragg wavelength of the PFBG was measured at temperatures from 295 to 4.2 K. A pressure-induced transition occurred at 200 K during the cooling cycle. As a result the temperature sensitivity of the PFBG was found to be nonlinear but reach 24 pm/K below 200 K, more than three times the regular FBG. For the temperature change from 80 K to 10 K, the PFBG has a total Bragg wavelength shift of about 470 pm, 10 times more than the regular FBG. From room temperature to liquid helium temperature the PFBG gives a total wavelength shift of 3.78 nm, compared to the FBG of 1.51 nm. The effect of the coating thickness on the temperature sensitivity of the gratings is also discussed.

  10. Sensitivity of regional forest carbon budgets to continuous and stochastic climate change pressures

    NASA Astrophysics Data System (ADS)

    Sulman, B. N.; Desai, A. R.; Scheller, R. M.

    2010-12-01

    Climate change is expected to impact forest-atmosphere carbon budgets through three processes: 1. Increased disturbance rates, including fires, mortality due to pest outbreaks, and severe storms 2. Changes in patterns of inter-annual variability, related to increased incidence of severe droughts and defoliating insect outbreaks 3. Continuous changes in forest productivity and respiration, related to increases in mean temperature, growing season length, and CO2 fertilization While the importance of these climate change effects in future regional carbon budgets has been established, quantitative characterization of the relative sensitivity of forested landscapes to these different types of pressures is needed. We present a model- and- data-based approach to understanding the sensitivity of forested landscapes to climate change pressures. Eddy-covariance and biometric measurements from forests in the northern United States were used to constrain two forest landscape models. The first, LandNEP, uses a prescribed functional form for the evolution of net ecosystem productivity (NEP) over the age of a forested grid cell, which is reset following a disturbance event. This model was used for investigating the basic statistical properties of a simple landscape’s responses to climate change pressures. The second model, LANDIS-II, includes different tree species and models forest biomass accumulation and succession, allowing us to investigate the effects of more complex forest processes such as species change and carbon pool accumulation on landscape responses to climate change effects. We tested the sensitivity of forested landscapes to these three types of climate change pressures by applying ensemble perturbations of random disturbance rates, distribution functions of inter-annual variability, and maximum potential carbon uptake rates, in the two models. We find that landscape-scale net carbon exchange responds linearly to continuous changes in potential carbon uptake and

  11. SOLVENT-BASED TO WATERBASED ADHESIVE-COATED SUBSTRATE RETROFIT - VOLUME IV: FILM AND LABEL MANUFACTURING CASE STUDY: FLEXCON COMPANY, INC.

    EPA Science Inventory

    This volume discusses a visit to a site operated by FLEXcon Company, Inc., a pressure-sensitive adhesive coater, to collect information on the pollution prevention opportunities and barriers associated with waterbased adhesives. The purpose of the visit to FLEXcon was to gather i...

  12. Anaerobic adhesives and sealants. January 1970-December 1987 (citations from the US Patent data base). Report for January 1970-December 1987

    SciTech Connect

    Not Available

    1987-12-01

    This bibliography contains citations of selected patents concerning anaerobically curable adhesive compositions and sealants. Polymethacrylate, and urethane-based compounds are among those discussed. Pressure-sensitive anaerobic adhesives, and bonding methods are included. (This updated bibliography contains 115 citations, 22 of which are new entries to the previous edition.)

  13. The Effect of Micrite on Velocity, Its Sensitivity to Pressure, and Dissolution of Carbonates

    NASA Astrophysics Data System (ADS)

    El Husseiny, A.; Vanorio, T.

    2014-12-01

    This study investigates the effect of micrite on the acoustic properties of well-controlled microstructures created in the laboratory to closely mimic carbonate rocks. In particular, we examine the effect of micrite content on the elastic stiffness rock, its sensitivity to pressure, and induced dissolution upon saturation with a reactive fluid. We followed Dunham's classification and fabricated the samples by mixing coarse (sand size) and very fine (micrite size) calcite grains in different ratios, with the addition of cement and then cold-compressing the mixture. The acoustic velocities were measured under bench-top conditions and as functions of confining pressure before and after the injection of a CO2aqueous solution. Our bench-top measurements indicated that micrite makes the frame of the carbonate samples stiffer. Since the sensitivity of the elastic stiffness to pressure decreases as the content of micrite increases (see figure 1), we hypothesize a stiffer pore structure (i.e., rounder pores) in micrite-richer fabrics. Furthermore, the presence of micrite makes the carbonate sample more reactive upon dissolution. The concentration of Ca+2 cations in the fluid measured at the outlet after the injection of the CO2 aqueous solution shows larger dissolution in the micrite-rich samples likely due to the higher surface area of the micrite aggregates. The content of micrite also seems to affect the evolution of stiffness as dissolution proceeds. As the content of micrite increases, the enhanced dissolution translates into a marked softening of the rock frame. We conclude that the content of micrite can play an important role in the complex rock-fluid interaction of carbonates as well as when comparing Gassmann's predictions to velocity measurements of saturated carbonates.

  14. Asymmetric Yield Function Based on the Stress Invariants for Pressure Sensitive Metals

    SciTech Connect

    Jeong Wahn Yoon; Yanshan Lou; Jong Hun Yoon; Michael V. Glazoff

    2014-05-01

    A general asymmetric yield function is proposed with dependence on the stress invariants for pressure sensitive metals. The pressure sensitivity of the proposed yield function is consistent with the experimental result of Spitzig and Richmond (1984) for steel and aluminum alloys while the asymmetry of the third invariant is preserved to model strength differential (SD) effect of pressure insensitive materials. The proposed yield function is transformed in the space of the stress triaxaility, the von Mises stress and the normalized invariant to theoretically investigate the possible reason of the SD effect. The proposed plasticity model is further extended to characterize the anisotropic behavior of metals both in tension and compression. The extension of the yield function is realized by introducing two distinct fourth-order linear transformation tensors of the stress tensor for the second and third invariants, respectively. The extended yield function reasonably models the evolution of yield surfaces for a zirconium clock-rolled plate during in-plane and through-thickness compression reported by Plunkett et al. (2007). The extended yield function is also applied to describe the orthotropic behavior of a face-centered cubic metal of AA 2008-T4 and two hexagonal close-packed metals of high-purity-titanium and AZ31 magnesium alloy. The orthotropic behavior predicted by the generalized model is compared with experimental results of these metals. The comparison validates that the proposed yield function provides sufficient predictability on SD effect and anisotropic behavior both in tension and compression. When it is necessary to consider r-value anisotropy, the proposed function is efficient to be used with nonassociated flow plasticity by introducing a separate plastic potential for the consideration of r-values as shown in Stoughton & Yoon (2004, 2009).

  15. Bio-Inspired Pressure Sensitive Foam Arrays for use in Hydrodynamic Sensing Applications

    NASA Astrophysics Data System (ADS)

    Dusek, Jeff; Triantafyllou, Michael; Lang, Jeffrey

    2015-11-01

    Shallow, turbid, and highly dynamic coastal waters provide a challenging environment for safe and reliable operation of marine vehicles faced with a distinct environmentally driven perceptual deficit. In nature, fish have solved this perplexing sensory problem and exhibit an intimate knowledge of the near-body flow field. This enhanced perception is mediated by the ability to discern and interpret hydrodynamic flow structures through the velocity and pressure sensing capabilities of the fish's lateral line. Taking cues from biological sensory principles, highly conformal pressure sensor arrays have been developed utilizing a novel piezoresistive carbon black-PDMS foam active material. By leveraging the low Young's modulus and watertight structure of closed-cell PDMS (silicone) foam, the sensor arrays are well suited for hydrodynamic sensing applications and prolonged exposure to fluid environments. Prototype arrays were characterized experimentally using hydrodynamic stimuli inspired by biological flows, and were found to exhibit a high degree of sensitivity while improving on the flexibility, robustness, and cost of existing pressure sensors.

  16. Pressure-Sensitive Touch Panel Based on Piezoelectric Poly(L-lactic acid) Film

    NASA Astrophysics Data System (ADS)

    Ando, Masamichi; Kawamura, Hideki; Kitada, Hiroaki; Sekimoto, Yasuyuki; Inoue, Takafumi; Tajitsu, Yoshiro

    2013-09-01

    Poly(lactic acid) (PLA) is a widely used biomass-derived polymer. It is chiral because the lactic acid monomer has an asymmetric carbon. If the L-lactide is polymerized, then the PLA polymer is an L-type PLA or poly(L-lactic acid) (PLLA); if the D-lactide in PLA is polymerized, then the polymer is a D-type PLA (PDLA). When these polymers undergo drawing or elongation, they exhibit shear piezoelectricity. PLA films are highly transparent and do not exhibit pyroelectricity because of the lack of intrinsic polarization. Therefore, if a PLLA film is used for a touch panel, which is operated by pressure, there is no spurious signal due to heating from the fingers. This suggests that PLLA films may be suitable for touch panels using pressure detection. We used PLLA as the base film of a projected capacitive touch panel with multiple electrodes, and demonstrated a multitouch gesture screen that was sensitive to pressure applied on the screen. This touch panel technology has potential applications for smart phones and tablet personal computers.

  17. Reusable antifouling viscoelastic adhesive with an elastic skin.

    PubMed

    Patil, Sandip; Malasi, Abhinav; Majumder, Abhijit; Ghatak, Animangsu; Sharma, Ashutosh

    2012-01-10

    Although the viscoelasticity or tackiness of a pressure-sensitive adhesive gives it strength owing to energy dissipation during peeling, it also renders it nonreusable because of structural changes such as the formation of fibrils, cohesive failure, and fouling. However, an elastic layer has good structural integrity and cohesive strength but low adhesive energy. We demonstrate an effective composite adhesive in which a soft viscoelastic bulk layer is imbedded in a largely elastic thin skin layer. The composite layer is able to meet the conflicting demands of the high peel strength comparable to the viscoelastic core and the structural integrity, reusability, and antifouling properties of the elastic skin. Our model adhesive is made of poly(dimethylsiloxane), where its core and skin are created by varying the cross-linking percentage from 2 to 10%. PMID:22201420

  18. Extremely sensitive CWA analyzer based on a novel optical pressure sensor in photoacoustic gas analysis

    NASA Astrophysics Data System (ADS)

    Kauppinen, Jyrki K.; Koskinen, Vesa; Uotila, Juho; Kauppinen, Ismo K.

    2004-12-01

    Major improvement into the sensitivity of broadband Fourier transform infrared (FTIR) spectrometers, used in gas analysis, can be achieved by a photoacoustic detection system, which bases on a recently introduced optical pressure sensor. The sensor is a cantilever-type microphone with interferometric measurement of its free end displacement. By using a preliminary prototype of the photoacoustic gas detector, equipped with the proposed sensor and a black body radiation source, a detection limit in the sub-ppb range was obtained for e.g. methane gas. The limit, obtained in non-resonant operation mode, is very close to the best photoacoustic results achieved with powerfull laser sources and by exploiting the cell resonances. It is also orders of magnitude better than any measurement with a black body radiation source. Furthermore, the ultimate sensitivity leads on to very small detection limits also for several chemical warfare agents (CWA) e.g. sarin, tabun and mustard. The small size of the sensor and its great thermal stability enables the construction of an extremely sensitive portable CWA analyzer in the near future.

  19. Reliability and validity of pressure and temporal parameters recorded using a pressure-sensitive insole during running.

    PubMed

    Mann, Robert; Malisoux, Laurent; Brunner, Roman; Gette, Paul; Urhausen, Axel; Statham, Andrew; Meijer, Kenneth; Theisen, Daniel

    2014-01-01

    Running biomechanics has received increasing interest in recent literature on running-related injuries, calling for new, portable methods for large-scale measurements. Our aims were to define running strike pattern based on output of a new pressure-sensitive measurement device, the Runalyser, and to test its validity regarding temporal parameters describing running gait. Furthermore, reliability of the Runalyser measurements was evaluated, as well as its ability to discriminate different running styles. Thirty-one healthy participants (30.3 ± 7.4 years, 1.78 ± 0.10 m and 74.1 ± 12.1 kg) were involved in the different study parts. Eleven participants were instructed to use a rearfoot (RFS), midfoot (MFS) and forefoot (FFS) strike pattern while running on a treadmill. Strike pattern was subsequently defined using a linear regression (R(2)=0.89) between foot strike angle, as determined by motion analysis (1000 Hz), and strike index (SI, point of contact on the foot sole, as a percentage of foot sole length), as measured by the Runalyser. MFS was defined by the 95% confidence interval of the intercept (SI=43.9-49.1%). High agreement (overall mean difference 1.2%) was found between stance time, flight time, stride time and duty factor as determined by the Runalyser and a force-measuring treadmill (n=16 participants). Measurements of the two devices were highly correlated (R ≥ 0.80) and not significantly different. Test-retest intra-class correlation coefficients for all parameters were ≥ 0.94 (n=14 participants). Significant differences (p<0.05) between FFS, RFS and habitual running were detected regarding SI, stance time and stride time (n=24 participants). The Runalyser is suitable for, and easily applicable in large-scale studies on running biomechanics. PMID:24054346

  20. Structure and phase diagram of an adhesive colloidal dispersion under high pressure: A small angle neutron scattering, diffusing wave spectroscopy, and light scattering study

    NASA Astrophysics Data System (ADS)

    Vavrin, R.; Kohlbrecher, J.; Wilk, A.; Ratajczyk, M.; Lettinga, M. P.; Buitenhuis, J.; Meier, G.

    2009-04-01

    We have applied small angle neutron scattering (SANS), diffusing wave spectroscopy (DWS), and dynamic light scattering (DLS) to investigate the phase diagram of a sterically stabilized colloidal system consisting of octadecyl grafted silica particles dispersed in toluene. This system is known to exhibit gas-liquid phase separation and percolation, depending on temperature T, pressure P, and concentration φ. We have determined by DLS the pressure dependence of the coexistence temperature and the spinodal temperature to be dP /dT=77 bar/K. The gel line or percolation limit was measured by DWS under high pressure using the condition that the system became nonergodic when crossing it and we determined the coexistence line at higher volume fractions from the DWS limit of turbid samples. From SANS measurements we determined the stickiness parameter τB(P,T,φ) of the Baxter model, characterizing a polydisperse adhesive hard sphere, using a global fit routine on all curves in the homogenous regime at various temperatures, pressures, and concentrations. The phase coexistence and percolation line as predicted from τB(P,T,φ) correspond with the determinations by DWS and were used to construct an experimental phase diagram for a polydisperse sticky hard sphere model system. A comparison with theory shows good agreement especially concerning the predictions for the percolation threshold. From the analysis of the forward scattering we find a critical scaling law for the susceptibility corresponding to mean field behavior. This finding is also supported by the critical scaling properties of the collective diffusion.

  1. A multi-center, randomized, clinical trial comparing adhesive polyurethane foam dressing and adhesive hydrocolloid dressing in patients with grade II pressure ulcers in primary care and nursing homes

    PubMed Central

    2013-01-01

    Background Pressure ulcers (PrUs) are ischemic wounds in the skin and underlying tissues caused by long-standing pressure force over an external bone or cartilaginous surface. PrUs are an important challenge for the overall health system because can prolong patient hospitalization and reduce quality of life. Moreover, 95% of PrUs are avoidable, suggesting they are caused by poor quality care assistance. PrUs are also costly, increasing national costs. For example, they represent about 5% of overall annual health expenses in Spain. Stages I and II PrUs have a combined prevalence of 65%. According main clinical guidelines, stage II PrUs (PrU-IIs) are usually treated by applying special dressings (polyurethane or hydrocolloid). However, little scientific evidence regarding their efficacy has been identified in scientific literature. Our aim is to assess the comparative efficacy of adhesive polyurethane foam and hydrocolloid dressings in the treatment of PrU-IIs in terms of healed ulcer after 8 weeks of follow-up. Methods/design This paper describes the development and evaluation protocol of a randomized clinical trial of two parallel treatment arms. A total of 820 patients with at least 1 PrU-II will be recruited from primary health care and home care centers. All patients will receive standardized healing procedures and preventive measures (e.g. positional changes and pressure-relieving support surfaces), following standardized procedures. The main outcome will be the percentage of wounds healed after 8 weeks. Secondary outcomes will include cost-effectiveness, as evaluated by cost per healed ulcer and cost per treated patient and safety evaluated by adverse events. Discussion This trial will address the hypothesis that hydrocolloid dressings will heal at least 10% more stage II PrUs and be more cost-effective than polyurethane foam dressings after 8 weeks. Trial registration This trial has been registered with controlled-trials number ISCRCTN57842461 and Eudra

  2. Experimental demonstration of the utility of pressure sensitivity kernels in time-reversal.

    PubMed

    Raghukumar, Kaustubha; Cornuelle, Bruce D; Hodgkiss, William S; Kuperman, William A

    2010-09-01

    Pressure sensitivity kernels were recently applied to time-reversal acoustics in an attempt to explain the enhanced stability of the time-reversal focal spot [Raghukumar et al., J. Acoust. Soc. Am. 124, 98-112 (2008)]. The theoretical framework developed was also used to derive optimized source functions, closely related to the inverse filter. The use of these optimized source functions results in an inverse filter-like focal spot which is more robust to medium sound speed fluctuations than both time-reversal and the inverse filter. In this paper the theory is applied to experimental data gathered during the Focused Acoustic Fields experiment, conducted in 2005, north of Elba Island in Italy. Sensitivity kernels are calculated using a range-independent sound-speed profile, for a geometry identical to that used in the experiment, and path sensitivities are identified with observed arrivals. The validity of the kernels in tracking time-evolving Green's functions is studied, along with limitations that result from a linearized analysis. An internal wave model is used to generate an ensemble of sound speed profiles, which are then used along with the calculated sensitivity kernels to derive optimized source functions. Focal spots obtained using the observed Green's functions with these optimized source functions are then compared to those obtained using time-reversal and the inverse-filter. It is shown that these functions are able to provide a focal spot superior to time-reversal while being more robust to sound speed fluctuations than the inverse filter or time-reversal. PMID:20815436

  3. Improving the Sensitivity of Mass Spectrometry by Using a New Sheath Flow Electrospray Emitter Array at Subambient Pressures

    PubMed Central

    Cox, Jonathan T.; Marginean, Ioan; Kelly, Ryan T.; Smith, Richard D.; Tang, Keqi

    2014-01-01

    Arrays of chemically etched emitters with individualized sheath gas capillaries were developed to enhance electrospray ionization (ESI) efficiency at subambient pressures. By incorporating the new emitter array in a subambient pressure ionization with nanoelectrospray (SPIN) source, both ionization efficiency and ion transmission efficiency were significantly increased, providing enhanced sensitivity in mass spectrometric analyses. The SPIN source eliminates the major ion losses of conventional ESI-mass spectrometry (MS) interfaces by placing the emitter in the first reduced pressure region of the instrument. The new ESI emitter array design developed in this study allows individualized sheath gas around each emitter in the array making it possible to generate an array of uniform and stable electrosprays in the subambient pressure (10 to 30 Torr) environment for the first time. The utility of the new emitter arrays was demonstrated by coupling the emitter array/SPIN source with a time of flight (TOF) mass spectrometer. The instrument sensitivity was compared under different ESI source and interface configurations including a standard atmospheric pressure single ESI emitter/heated capillary, single emitter/SPIN and multi-emitter/SPIN configurations using an equimolar solution of 9 peptides. The highest instrument sensitivity was observed using the multi-emitter/SPIN configuration in which the sensitivity increased with the number of emitters in the array. Over an order of magnitude MS sensitivity improvement was achieved using multi-emitter/SPIN as compared to using the standard atmospheric pressure single ESI emitter/heated capillary interface. PMID:24676894

  4. Biomechanics of shear-sensitive adhesion in climbing animals: peeling, pre-tension and sliding-induced changes in interface strength.

    PubMed

    Labonte, David; Federle, Walter

    2016-09-01

    Many arthropods and small vertebrates use adhesive pads for climbing. These biological adhesives have to meet conflicting demands: attachment must be strong and reliable, yet detachment should be fast and effortless. Climbing animals can rapidly and reversibly control their pads' adhesive strength by shear forces, but the mechanisms underlying this coupling have remained unclear. Here, we show that adhesive forces of stick insect pads closely followed the predictions from tape peeling models when shear forces were small, but strongly exceeded them when shear forces were large, resulting in an approximately linear increase of adhesion with friction. Adhesion sharply increased at peel angles less than ca 30°, allowing a rapid switch between attachment and detachment. The departure from classic peeling theory coincided with the appearance of pad sliding, which dramatically increased the peel force via a combination of two mechanisms. First, partial sliding pre-stretched the pads, so that they were effectively stiffer upon detachment and peeled increasingly like inextensible tape. Second, pad sliding reduces the thickness of the fluid layer in the contact zone, thereby increasing the stress levels required for peeling. In combination, these effects can explain the coupling between adhesion and friction that is fundamental to adhesion control across all climbing animals. Our results highlight that control of adhesion is not solely achieved by direction-dependence and morphological anisotropy, suggesting promising new routes for the development of controllable bio-inspired adhesives. PMID:27605165

  5. Development of fast response bi-luminophore pressure-sensitive paint by means of an inkjet printing technique

    NASA Astrophysics Data System (ADS)

    Egami, Y.; Ueyama, J.; Furukawa, S.; Kameya, T.; Matsuda, Y.; Yamaguchi, H.; Niimi, T.

    2015-06-01

    A novel fast response bi-luminophore pressure-sensitive paint (PSP) by inkjet printing of sensor-dot arrays on an anodized aluminum (AA) substrate has been developed for unsteady flow measurements. A bi-luminophore AA-PSP, which is a combination of PSP and temperature-sensitive paint (TSP), is essential for precise pressure measurements, because the PSP result needs the temperature correction. However, a conventional bi-luminophore AA-PSP prepared by a dipping method does not work well due to the interference between the PSP and TSP luminophores. To overcome this problem, we have developed isolated dot arrays of PSP and TSP formed on an anodized aluminum substrate by an inkjet printing method. In this study, platinum tetrakis (pentafluorophenyl) porphyrin (PtTFPP) and ZnS-AgInS2 (ZAIS) were employed as pressure- and temperature-sensitive dyes, respectively. A suitable solvent was chosen for each dye to form the dots with uniform, high luminescence intensity, and high sensitivity. The developed bi-luminophore AA-PSP could simultaneously measure pressure and temperature and could reduce the temperature effect of the PSP from -0.97%/K (without temperature correction) to -0.01%/K (with temperature correction). It showed a pressure response time of 17.8  ±  0.8 μs at 90% pressure rise to a step change of pressure, which is in the same range as a conventional AA-PSP.

  6. The effects of cold atmospheric plasma on cell adhesion, differentiation, migration, apoptosis and drug sensitivity of multiple myeloma.

    PubMed

    Xu, Dehui; Luo, Xiaohui; Xu, Yujing; Cui, Qingjie; Yang, Yanjie; Liu, Dingxin; Chen, Hailan; Kong, Michael G

    2016-05-13

    Cold atmospheric plasma was shown to induce cell apoptosis in numerous tumor cells. Recently, some other biological effects, such as induction of membrane permeation and suppression of migration, were discovered by plasma treatment in some types of tumor cells. In this study, we investigated the biological effects of plasma treatment on multiple myeloma cells. We detected the detachment of adherent myeloma cells by plasma, and the detachment area was correlated with higher density of hydroxyl radical in the gas phase of the plasma. Meanwhile, plasma could promote myeloma differentiation by up-regulating Blimp-1 and XBP-1 expression. The migration ability was suppressed by plasma treatment through decreasing of MMP-2 and MMP-9 secretion. In addition, plasma could increase bortezomib sensitivity and induce myeloma cell apoptosis. Taking together, combination with plasma treatment may enhance current chemotherapy and probably improve the outcomes. PMID:27067049

  7. Stretchable Array of Highly Sensitive Pressure Sensors Consisting of Polyaniline Nanofibers and Au-Coated Polydimethylsiloxane Micropillars.

    PubMed

    Park, Heun; Jeong, Yu Ra; Yun, Junyeong; Hong, Soo Yeong; Jin, Sangwoo; Lee, Seung-Jung; Zi, Goangseup; Ha, Jeong Sook

    2015-10-27

    We report on the facile fabrication of a stretchable array of highly sensitive pressure sensors. The proposed pressure sensor consists of the top layer of Au-deposited polydimethylsiloxane (PDMS) micropillars and the bottom layer of conductive polyaniline nanofibers on a polyethylene terephthalate substrate. The sensors are operated by the changes in contact resistance between Au-coated micropillars and polyaniline according to the varying pressure. The fabricated pressure sensor exhibits a sensitivity of 2.0 kPa(-1) in the pressure range below 0.22 kPa, a low detection limit of 15 Pa, a fast response time of 50 ms, and high stability over 10000 cycles of pressure loading/unloading with a low operating voltage of 1.0 V. The sensor is also capable of noninvasively detecting human-pulse waveforms from carotid and radial artery. A 5 × 5 array of the pressure sensors on the deformable substrate, which consists of PDMS islands for sensors and the mixed thin film of PDMS and Ecoflex with embedded liquid metal interconnections, shows stable sensing of pressure under biaxial stretching by 15%. The strain distribution obtained by the finite element method confirms that the maximum strain applied to the pressure sensor in the strain-suppressed region is less than 0.04% under a 15% biaxial strain of the unit module. This work demonstrates the potential application of our proposed stretchable pressure sensor array for wearable and artificial electronic skin devices. PMID:26381467

  8. Pressure sensitivity of the conductivity of phthalocyanine complexes with divalent metals

    SciTech Connect

    Berlin, Y.A.; Beshenko, S.I.; Danielyan, N.G.; Enikolopyan, N.S.; Mikhaelenko, S.A.; Zhorin, V.A.

    1985-11-01

    This paper studies the effect of HP on electrical conductivity of Pc and its metal complexes (NiPc, ZnPc, CoPc, CuPc). The Co, Ni, and ZnPc complexes were synthesized by known procedures, and the compounds were purified by repeated boiling with dilute aqueous HCI and NH/sub 4/OH. Extraction of impurities with hot methanol was performed until the extract was colorless. Industrial batch-produced PcCu was further purified by extraction of impurities with hot methanol. Resuylts point to the possibility of regulating the electrical conductivity of Pc compounds and the high-pressure sensitivity of some of their electrophysical properties, by introducing the appropriate divalent metal atoms into the phthalocyanine macroing.

  9. Silver nanowire-embedded PDMS with a multiscale structure for a highly sensitive and robust flexible pressure sensor.

    PubMed

    Joo, Yunsik; Byun, Junghwan; Seong, Narkhyeon; Ha, Jewook; Kim, Hyunjong; Kim, Sangwoo; Kim, Taehoon; Im, Hwarim; Kim, Donghyun; Hong, Yongtaek

    2015-04-14

    The development of highly sensitive pressure sensors with a low-cost and facile fabrication technique is desirable for electronic skins and wearable sensing devices. Here a low-cost and facile fabrication strategy to obtain multiscale-structured elastomeric electrodes and a highly sensitive and robust flexible pressure sensor is presented. The principles of spontaneous buckle formation of the PDMS surface and the embedding of silver nanowires are used to fabricate the multiscale-structured elastomeric electrode. By laminating the multiscale-structured elastomeric electrode onto the dielectric layer/bottom electrode template, the pressure sensor can be obtained. The pressure sensor is based on the capacitive sensing mechanism and shows high sensitivity (>3.8 kPa(-1)), fast response and relaxation time (<150 ms), high bending stability and high cycle stability. The fabrication process can be easily scaled up to produce pressure sensor arrays and they can detect the spatial distribution of the applied pressure. It is also demonstrated that the fingertip pressure sensing device can sense the pressure distribution of each finger, when grabbing an object. PMID:25779911

  10. Enhanced adhesion of dopamine methacrylamide elastomers via viscoelasticity tuning.

    PubMed

    Chung, Hoyong; Glass, Paul; Pothen, Jewel M; Sitti, Metin; Washburn, Newell R

    2011-02-14

    We present a study on the effects of cross-linking on the adhesive properties of bio-inspired 3,4-dihydroxyphenylalanine (DOPA). DOPA has a unique catechol moiety found in adhesive proteins in marine organisms, such as mussels and polychaete, which results in strong adhesion in aquatic conditions. Incorporation of this functional group in synthetic polymers provides the basis for pressure-sensitive adhesives for use in a broad range of environments. A series of cross-linked DOPA-containing polymers were prepared by adding divinyl cross-linking agent ethylene glycol dimethacrylate (EGDMA) to monomer mixtures of dopamine methacrylamide (DMA) and 2-methoxyethyl acrylate (MEA). Samples were prepared using a solvent-free microwave-assisted polymerization reaction and compared to a similar series of cross-linked MEA materials. Cross-linking with EGDMA tunes the viscoelastic properties of the adhesive material and has the advantage of not reacting with the catechol group that is responsible for the excellent adhesive performance of this material. Adhesion strength was measured by uniaxial indentation tests, which indicated that 0.001 mol % of EGDMA-cross-linked copolymer showed the highest work of adhesion in dry conditions, but non-cross-linked DMA was the highest in wet conditions. The results suggest that there is an optimal cross-linking degree that displays the highest adhesion by balancing viscous and elastic behaviors of the polymer but this appears to depend on the conditions. This concentration of cross-linker is well below the theoretical percolation threshold, and we propose that subtle changes in polymer viscoelastic properties can result in significant improvements in adhesion of DOPA-based materials. The properties of lightly cross-linked poly(DMA-co-MEA) were investigated by measurement of the frequency dependence of the storage modulus (G') and loss modulus (G''). The frequency-dependence of G' and magnitude of G'' showed gradual decreases with the

  11. The Role of Glottal Surface Adhesion on Vocal Folds Biomechanics

    PubMed Central

    Bhattacharya, Pinaki; Siegmund, Thomas

    2014-01-01

    The airway surface liquid (ASL) is a very thin mucus layer and covers the vocal fold (VF) surface. Adhesion mediated by the ASL occurs during phonation as the VFs separate after collision. Such adhesion is hypothesized to determine voice quality and health. However, biomechanical insights into the adhesive processes during VF oscillation are lacking. Here, a computational study is reported on self-sustained VF vibration involving contact and adhesion. The VF structural model and the glottal airflow are considered fully three-dimensional. The mechanical behavior of the ASL is described through a constitutive traction–separation law where mucosal cohesive strength, cohesive energy and rupture length enter. Cohesive energy values considered are bound below by the cohesive energy of water at standard temperature and pressure. Cohesive strength values considered are bound above by prior reported data on the adhesive strength of mucosal surface of rat small intestine. This model introduces a mechanical length scale into the analysis. The sensitivity of various aspects of VF dynamics such as flow-declination rate, VF separation under adhesive condition and formation of multiple local fluid bridges is determined in relation to specific ASL adhesive properties. It is found that for the ASL considered here, the characteristics of the VF separation process are of debond type. Instabilities lead to the breakup of the bond area into several smaller bond patches. Such finding is consistent with in-vivo observations. PMID:25034504

  12. Quantitative and sensitive analysis of CN molecules using laser induced low pressure He plasma

    NASA Astrophysics Data System (ADS)

    Pardede, Marincan; Hedwig, Rinda; Abdulmadjid, Syahrun Nur; Lahna, Kurnia; Idris, Nasrullah; Jobiliong, Eric; Suyanto, Hery; Marpaung, Alion Mangasi; Suliyanti, Maria Margaretha; Ramli, Muliadi; Tjia, May On; Lie, Tjung Jie; Lie, Zener Sukra; Kurniawan, Davy Putra; Kurniawan, Koo Hendrik; Kagawa, Kiichiro

    2015-03-01

    We report the results of experimental study on CN 388.3 nm and C I 247.8 nm emission characteristics using 40 mJ laser irradiation with He and N2 ambient gases. The results obtained with N2 ambient gas show undesirable interference effect between the native CN emission and the emission of CN molecules arising from the recombination of native C ablated from the sample with the N dissociated from the ambient gas. This problem is overcome by the use of He ambient gas at low pressure of 2 kPa, which also offers the additional advantages of cleaner and stronger emission lines. The result of applying this favorable experimental condition to emission spectrochemical measurement of milk sample having various protein concentrations is shown to yield a close to linear calibration curve with near zero extrapolated intercept. Additionally, a low detection limit of 5 μg/g is found in this experiment, making it potentially applicable for quantitative and sensitive CN analysis. The visibility of laser induced breakdown spectroscopy with low pressure He gas is also demonstrated by the result of its application to spectrochemical analysis of fossil samples. Furthermore, with the use of CO2 ambient gas at 600 Pa mimicking the Mars atmosphere, this technique also shows promising applications to exploration in Mars.

  13. Quantitative and sensitive analysis of CN molecules using laser induced low pressure He plasma

    SciTech Connect

    Pardede, Marincan; Hedwig, Rinda; Abdulmadjid, Syahrun Nur; Lahna, Kurnia; Idris, Nasrullah; Ramli, Muliadi; Jobiliong, Eric; Suyanto, Hery; Marpaung, Alion Mangasi; Suliyanti, Maria Margaretha; Tjia, May On

    2015-03-21

    We report the results of experimental study on CN 388.3 nm and C I 247.8 nm emission characteristics using 40 mJ laser irradiation with He and N{sub 2} ambient gases. The results obtained with N{sub 2} ambient gas show undesirable interference effect between the native CN emission and the emission of CN molecules arising from the recombination of native C ablated from the sample with the N dissociated from the ambient gas. This problem is overcome by the use of He ambient gas at low pressure of 2 kPa, which also offers the additional advantages of cleaner and stronger emission lines. The result of applying this favorable experimental condition to emission spectrochemical measurement of milk sample having various protein concentrations is shown to yield a close to linear calibration curve with near zero extrapolated intercept. Additionally, a low detection limit of 5 μg/g is found in this experiment, making it potentially applicable for quantitative and sensitive CN analysis. The visibility of laser induced breakdown spectroscopy with low pressure He gas is also demonstrated by the result of its application to spectrochemical analysis of fossil samples. Furthermore, with the use of CO{sub 2} ambient gas at 600 Pa mimicking the Mars atmosphere, this technique also shows promising applications to exploration in Mars.

  14. Assessment of baroreflex sensitivity from spontaneous oscillations of blood pressure and heart rate: proven clinical value?

    PubMed

    Pinna, Gian Domenico; Maestri, Roberto; La Rovere, Maria Teresa

    2015-04-01

    The baroreceptor-heart rate reflex (baroreflex sensitivity, BRS) is a key mechanism contributing to the neural regulation of the cardiovascular system. Several methods have been proposed so far to assess BRS by analyzing the spontaneous beat-to-beat fluctuations of arterial blood pressure and heart rate. These methods are inherently simple, non-invasive and low-cost. This study is an attempt to address the question of whether spontaneous baroreflex methods have proven to be of value in the clinical setting. In the first part of this article, we critically review most representative clinical studies using spontaneous BRS techniques either for risk stratification or treatment evaluation, these being major issues in the clinical management of the patients. In the second part, we address two important aspects of spontaneous BRS measurements: measurability and reliability. Estimation of BRS in the studies selected for the review was performed according to the sequence, transfer function, alpha-index and phase-rectified signal averaging method. Arterial blood pressure was recorded non-invasively during supine, short-term (<30 min) laboratory recordings. The conclusion from this review is that spontaneous BRS techniques have been shown to be of great value in clinical practice but further work is needed to confirm the validity of previous findings and to widen the field of clinical applications. Measurability and reliability can be a major issue in the measurement of spontaneous BRS, particularly in some patient populations like post-myocardial infarction and heart failure patents. Main causes of poor measurability are: non-sinus rhythm, a high rate of ectopic beats and the need for recorded time series of RR interval and arterial blood pressure to satisfy the constraints of the different BRS estimation algorithms. As for reliability, within-subject variability is rather high in the measurements of spontaneous BRS and, therefore, should be carefully taken into account

  15. MEMS Biomimetic Acoustic Pressure Gradient Sensitive Structure for Sound Source Localization

    PubMed Central

    An, Peng; Yuan, Weizheng; Ren, Sen

    2009-01-01

    The parasitoid fly Ormia ochracea shows an astonishing localization ability with its tiny hearing organ. A novel MEMS biomimetic acoustic pressure gradient sensitive structure was designed and fabricated by mimicking the mechanically coupled tympana of the fly. Firstly, the analytic representation formulas of the resultant force and resultant moment of the incoming plane wave acting on the structure were derived. After that, structure modal analysis was performed and the results show that the structure has out-of-phase and in-phase vibration modes, and the corresponding eigenfrequency is decided by the stiffness of vertical torsional beam and horizontal beam respectively. Acoustic-structural coupled analysis was performed and the results show that phase difference and amplitude difference between the responses of the two square diaphragms of the sensitive structure are effectively enlarged through mechanical coupling beam. The phase difference and amplitude difference increase with increasing incident angle and can be used to distinguish the direction of sound arrival. At last, the fabrication process and results of the device is also presented. PMID:22346718

  16. The sensitivity of the northwest European continental shelf ecosystem to anthropogenic pressures

    NASA Astrophysics Data System (ADS)

    Wakelin, Sarah; Artioli, Yuri; Holt, Jason; Butenschön, Momme

    2013-04-01

    Anthropogenic pressure is exerted on ecosystems in several ways, through direct drivers such as eutrophication and levels of fishing effort and by changes in the physical environment brought about by climate change. Changes in water temperature, the timing and duration of seasonal stratification, circulation patterns and ocean-shelf exchange all impact on shelf-sea primary production. We use a coupled hydrodynamics-ecosystem model (POLCOMS-ERSEM) to study ecosystem sensitivity to climate change and the anthropogenic drivers of river nutrient loads, impacting on eutrophication, and trawling effort on the northwest European continental shelf, with an emphasis on changes in the North Sea. To force the model we use data from a coupled ocean-atmosphere global model (IPSL-CM4) representative of conditions in the recent past (1983-2000) and possible conditions in the near future (2030-2040) under a business as usual emissions scenario SRES A1B. To study ecosystem sensitivity to direct anthropogenic forcing, we adopt two scenarios impacting on river nutrient loads and trawling effort - one where there is rapid economic growth and limited environmental policies and a second where economic growth is constrained by environmental objectives. The sensitivity of the system to each single driver: climate change, increase in river nutrient loads, decrease in river nutrient loads and reduction in trawling effort is explored. The response of the ecosystem to the combined effects of changes in multiple drivers under the two scenarios of economic growth is also studied. The results are relevant to the Marine Strategy Framework Directive descriptors on marine food webs, eutrophication and biodiversity.

  17. Stomatal sensitivity to vapour pressure deficit relates to climate of origin in Eucalyptus species.

    PubMed

    Bourne, Aimee E; Haigh, Anthony M; Ellsworth, David S

    2015-03-01

    Selecting plantation species to balance water use and production requires accurate models for predicting how species will tolerate and respond to environmental conditions. Although interspecific variation in water use occurs, species-specific parameters are rarely incorporated into physiologically based models because often the appropriate species parameters are lacking. To determine the physiological control over water use in Eucalyptus, five stands of Eucalyptus species growing in a common garden were measured for sap flux rates and their stomatal response to vapour pressure deficit (D) was assessed. Maximal canopy conductance and whole-canopy stomatal sensitivity to D and reduced water availability were lower in species originating from more arid climates of origin than those from humid climates. Species from humid climates showed a larger decline in maximal sap flux density (JSmax) with reduced water availability, and a lower D at which stomatal closure occurred than species from more arid climates, implying larger sensitivity to water availability and D in these species. We observed significant (P < 0.05) correlations of species climate of origin with mean vessel diameter (R(2) = 0.90), stomatal sensitivity to D (R(2) = 0.83) and the size of the decline in JSmax to restricted water availability (R(2) = 0.94). Thus aridity of climate of origin appears to have a selective role in constraining water-use response among the five Eucalyptus plantation species. These relationships emphasize that within this congeneric group of species, climate aridity constrains water use. These relationships have implications for species choices for tree plantation success against drought-induced losses and the ability to manage Eucalyptus plantations against projected changes in water availability and evaporation in the future. PMID:25769338

  18. Direct Growth of Graphene Films on 3D Grating Structural Quartz Substrates for High-Performance Pressure-Sensitive Sensors.

    PubMed

    Song, Xuefen; Sun, Tai; Yang, Jun; Yu, Leyong; Wei, Dacheng; Fang, Liang; Lu, Bin; Du, Chunlei; Wei, Dapeng

    2016-07-01

    Conformal graphene films have directly been synthesized on the surface of grating microstructured quartz substrates by a simple chemical vapor deposition process. The wonderful conformality and relatively high quality of the as-prepared graphene on the three-dimensional substrate have been verified by scanning electron microscopy and Raman spectra. This conformal graphene film possesses excellent electrical and optical properties with a sheet resistance of <2000 Ω·sq(-1) and a transmittance of >80% (at 550 nm), which can be attached with a flat graphene film on a poly(dimethylsiloxane) substrate, and then could work as a pressure-sensitive sensor. This device possesses a high-pressure sensitivity of -6.524 kPa(-1) in a low-pressure range of 0-200 Pa. Meanwhile, this pressure-sensitive sensor exhibits super-reliability (≥5000 cycles) and an ultrafast response time (≤4 ms). Owing to these features, this pressure-sensitive sensor based on 3D conformal graphene is adequately introduced to test wind pressure, expressing higher accuracy and a lower background noise level than a market anemometer. PMID:27269362

  19. Relationships between salt sensitivity of blood pressure and sympathetic nervous system activity: a short review of evidence.

    PubMed

    Strazzullo, P; Barbato, A; Vuotto, P; Galletti, F

    2001-01-01

    Experimental and clinical studies provided evidence in favor of complex relationships between sympathetic nervous system activity and salt-sensitivity of blood pressure. Genetic and acquired metabolic alterations associated with a tendency to retain salt and water may generate salt-sensitivity of blood pressure and shift the pressure-natriuresis curve to the right, promoting an increase in blood pressure. Sympathetic activation is a factor contributing to this result. Chronic high dietary salt intake is followed by a derangement in mechanisms of central sympathetic inhibition and then by an enhanced peripheral sympathetic tone. This, in turn, may generate salt-sensitivity of blood pressure by affecting renal hemodynamics, tubular sodium and water handling. Insulin resistance and sodium and water retention are prompted by high-fat (as well as high carbohydrate) diets, and by an increase in body fat mass. Also, aging is a condition of impaired interactions of the above factors. A gain in weight due to reduced physical activity, not followed by a parallel decrease in calorie intake, brings to a fall in insulin sensitivity. In many cases, the natural age-related decline of renal function is associated with a reduced physical exercise, hyperinsulinemia and sodium retention; sympathetic nervous system activity is enhanced and causes an increase in blood pressure. PMID:11270585

  20. Overexpression of stress-inducible OsBURP16, the β subunit of polygalacturonase 1, decreases pectin content and cell adhesion and increases abiotic stress sensitivity in rice.

    PubMed

    Liu, Huanhuan; Ma, Yan; Chen, Na; Guo, Siyi; Liu, Huili; Guo, Xiaoyu; Chong, Kang; Xu, Yunyuan

    2014-05-01

    Polygalacturonase (PG), one of the hydrolases responsible for cell wall pectin degradation, is involved in organ consenescence and biotic stress in plants. PG1 is composed of a catalytic subunit, PG2, and a non-catalytic PG1β subunit. OsBURP16 belongs to the PG1β-like subfamily of BURP-family genes and encodes one putative PG1β subunit precursor in rice (Oryza sativa L.). Transcription of OsBURP16 is induced by cold, salinity and drought stresses, as well as by abscisic acid (ABA) treatment. Analysis of plant survival rates, relative ion leakage rates, accumulation levels of H2 O2 and water loss rates of leaves showed that overexpression of OsBURP16 enhanced sensitivity to cold, salinity and drought stresses compared with controls. Young leaves of Ubi::OsBURP16 transgenic plants showed reduced cell adhesion and increased cuticular transpiration rate. Mechanical strength measurement of Ubi::OsBURP16 plants showed that reduced force was required to break leaves as compared with wild type. Transgenic rice showed enhanced PG activity and reduced pectin content. All these results suggested that overexpression of OsBURP16 caused pectin degradation and affected cell wall integrity as well as transpiration rate, which decreased tolerance to abiotic stresses. PMID:24237159

  1. 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 ...

  2. Hydrogen sulfide augments neutrophil migration through enhancement of adhesion molecule expression and prevention of CXCR2 internalization: role of ATP-sensitive potassium channels.

    PubMed

    Dal-Secco, Daniela; Cunha, Thiago M; Freitas, Andressa; Alves-Filho, José Carlos; Souto, Fabrício O; Fukada, Sandra Y; Grespan, Renata; Alencar, Nylane M N; Neto, Alberto F; Rossi, Marcos A; Ferreira, Sérgio H; Hothersall, John S; Cunha, Fernando Q

    2008-09-15

    In this study, we have addressed the role of H(2)S in modulating neutrophil migration in either innate (LPS-challenged naive mice) or adaptive (methylated BSA (mBSA)-challenged immunized mice) immune responses. Treatment of mice with H(2)S synthesis inhibitors, dl-propargylglycine (PAG) or beta-cyanoalanine, reduced neutrophil migration induced by LPS or methylated BSA (mBSA) into the peritoneal cavity and by mBSA into the femur/tibial joint of immunized mice. This effect was associated with decreased leukocyte rolling, adhesion, and P-selectin and ICAM-1 expression on endothelium. Predictably, treatment of animals with the H(2)S donors, NaHS or Lawesson's reagent, enhanced these parameters. Moreover, the NaHS enhancement of neutrophil migration was not observed in ICAM-1-deficient mice. Neither PAG nor NaHS treatment changed LPS-induced CD18 expression on neutrophils, nor did the LPS- and mBSA-induced release of neutrophil chemoattractant mediators TNF-alpha, keratinocyte-derived chemokine, and LTB(4). Furthermore, in vitro MIP-2-induced neutrophil chemotaxis was inhibited by PAG and enhanced by NaHS treatments. Accordingly, MIP-2-induced CXCR2 internalization was enhanced by PAG and inhibited by NaHS treatments. Moreover, NaHS prevented MIP-2-induced CXCR2 desensitization. The PAG and NaHS effects correlated, respectively, with the enhancement and inhibition of MIP-2-induced G protein-coupled receptor kinase 2 expression. The effects of NaHS on neutrophil migration both in vivo and in vitro, together with CXCR2 internalization and G protein-coupled receptor kinase 2 expression were prevented by the ATP-sensitive potassium (K(ATP)(+)) channel blocker, glybenclamide. Conversely, diazoxide, a K(ATP)(+) channel opener, increased neutrophil migration in vivo. Together, our data suggest that during the inflammatory response, H(2)S augments neutrophil adhesion and locomotion, by a mechanism dependent on K(ATP)(+) channels. PMID:18768887

  3. Highly sensitive multi-layer pressure sensor with an active nanostructured layer of an organic molecular metal

    NASA Astrophysics Data System (ADS)

    Laukhin, V.; Lebedev, V.; Laukhina, E.; Rovira, C.; Veciana, J.

    2016-03-01

    This work addresses to the modern technologies that need to be instrumented with lightweight highly sensitive pressure sensors. The paper presents the development of a new plain flexible thin pressure sensor using a nanostructured layer of the highly sensitive organic piezoresistive metal β-(BEDT-TTF)2I3 as an active component; BEDT-TTF=bis (ethylenedithio)tetrathiafulvalene. The original construction approach permits one to operate the developed sensor on the principle of electrical resistance variations when its piezoresistive layer is elongated under a pressure increase. The pressure sensing element and a set of gold electrodes were integrated into one compact multi-layer design. The construction was optimized to enable one generic design for pressure ranges from 1 to 400 bar. The pressure tests showed that the sensor is able to control a small pressure change as a well definite electrical signal. So the developed type of the sensors is very attractive as a new generation of compact, lightweight, low-cost sensors that might monitor pressure with a good level of measurement accuracy.

  4. A sensitive pressure sensor for diamond anvil cell experiments up to 2 GPa: FluoSpheres[reg

    SciTech Connect

    Picard, Aude; Oger, Phil M.; Daniel, Isabelle; Cardon, Herve; Montagnac, Gilles; Chervin, Jean-Claude

    2006-08-01

    We present an optical pressure sensor suitable for experiments in diamond anvil cell in the 0.1 MPa-2 GPa pressure range, for temperatures between ambient and 323 K. It is based on the pressure-dependent fluorescence spectrum of FluoSpheres[reg], which are commercially available fluorescent microspheres commonly used to measure blood flow in experimental biology. The fluorescence of microspheres is excited by the 514.5 nm line of an Ar{sup +} laser, and the resulting spectrum displays three very intense broad bands at 534, 558, and 598 nm, respectively. The reference wavelength and pressure gauge is that of the first inflection point of the spectrum, located at 525.6{+-}0.2 nm at ambient pressure. It is characterized by an instantaneous and large linear pressure shift of 9.93({+-}0.08) nm/GPa. The fluorescence of the FluoSpheres[reg] has been investigated as a function of pressure (0.1-4 GPa), temperature (295-343 K), pH (3-12), salinity, and pressure transmitting medium. These measurements show that, for pressures comprised between 0.1 MPa and 2 GPa, at temperatures not exceeding 323 K, at any pH, in aqueous pressure transmitting media, pressure can be calculated from the wavelength shift of two to three beads, according to the relation P=0.100 ({+-}0.001) {delta}{lambda}{sub i}(P) with {delta}{lambda}{sub i}(P)={lambda}{sub i}(P)-{lambda}{sub i}(0) and {lambda}{sub i}(P) as the wavelength of the first inflection point of the spectrum at the pressure P. This pressure sensor is approximately thirty times more sensitive than the ruby scale and responds instantaneously to pressure variations.

  5. A sensitive pressure sensor for diamond anvil cell experiments up to 2 GPa: FluoSpheres®

    NASA Astrophysics Data System (ADS)

    Picard, Aude; Oger, Phil M.; Daniel, Isabelle; Cardon, Hervé; Montagnac, Gilles; Chervin, Jean-Claude

    2006-08-01

    We present an optical pressure sensor suitable for experiments in diamond anvil cell in the 0.1MPa-2GPa pressure range, for temperatures between ambient and 323K. It is based on the pressure-dependent fluorescence spectrum of FluoSpheres®, which are commercially available fluorescent microspheres commonly used to measure blood flow in experimental biology. The fluorescence of microspheres is excited by the 514.5nm line of an Ar+ laser, and the resulting spectrum displays three very intense broad bands at 534, 558, and 598nm, respectively. The reference wavelength and pressure gauge is that of the first inflection point of the spectrum, located at 525.6±0.2nm at ambient pressure. It is characterized by an instantaneous and large linear pressure shift of 9.93(±0.08)nm/GPa. The fluorescence of the FluoSpheres® has been investigated as a function of pressure (0.1-4GPa), temperature (295-343K), pH (3-12), salinity, and pressure transmitting medium. These measurements show that, for pressures comprised between 0.1MPa and 2GPa, at temperatures not exceeding 323K, at any pH, in aqueous pressure transmitting media, pressure can be calculated from the wavelength shift of two to three beads, according to the relation P =0.100 (±0.001) Δλi(P ) with Δλi(P )=λi(P)-λi(0) and λi(P) as the wavelength of the first inflection point of the spectrum at the pressure P. This pressure sensor is approximately thirty times more sensitive than the ruby scale and responds instantaneously to pressure variations.

  6. Fracto-emission accompanying adhesive failure

    NASA Technical Reports Server (NTRS)

    Dickinson, J. T.

    1984-01-01

    The fractoemission characteristics of various material interfaces have been investigated experimentally. The interfaces studied include brittle materials/epoxy, glass/elastomers and brittle materials/pressure sensitive adhesives. Results are presented for both large (1 sq cm) planar surfaces together with a few small microns fibers (E-glass, S-glass, Kevlar, and graphite), and a small (10-500 micron) particles in polymer matrices. The composition and energies of the particles emitted during adhesive failure were measured over a wide range of time scales by means of conventional particle counting techniques and photon imaging. Measurements of the time dependence, energy distribution, crack velocity dependence, and spatial distribution of fractoemissive particles are also presented. Some correlations between the various fractoemission components are described in detail.

  7. Low-pressure systems and extreme precipitation in central India: sensitivity to temperature changes

    NASA Astrophysics Data System (ADS)

    Sørland, Silje Lund; Sorteberg, Asgeir

    2015-10-01

    Extreme rainfall events in the central Indian region are often related to the passage of synoptic scale monsoon low-pressure systems (LPS). This study uses the surrogate climate change method on ten monsoon LPS cases connected to observed extreme rainfall events, to investigate how sensitive the precipitation and runoff are to an idealized warmer and moister atmosphere. The ten cases are simulated with three different initial and lateral boundary conditions: the unperturbed control run, and two sets of perturbed runs where the atmospheric temperature is increased uniformly throughout the atmosphere, the specific humidity increased according to Clausius Clapeyron's relation, but the large-scale flow is unchanged. The difference between the control and perturbed simulations are mainly due to the imposed warming and feedback influencing the synoptic flow. The mean precipitation change with warming in the central Indian region is 18-20 %/K, with largest changes at the end of the LPS tracks. The LPS in the warmer runs are bringing more moisture further inland that is released as precipitation. In the perturbed runs the precipitation rate is increasing at all percentiles, and there is more frequent rainfall with very heavy intensities. This leads to a shift in which category that contributes most to the total precipitation: more of the precipitation is coming from the category with very heavy intensities. The runoff changes are similar to the precipitation changes, except the response in intensity of very heavy runoff, which is around twice the change in intensity of very heavy precipitation.

  8. Low-pressure systems and extreme precipitation in central India: sensitivity to temperature changes

    NASA Astrophysics Data System (ADS)

    Sørland, Silje Lund; Sorteberg, Asgeir

    2016-07-01

    Extreme rainfall events in the central Indian region are often related to the passage of synoptic scale monsoon low-pressure systems (LPS). This study uses the surrogate climate change method on ten monsoon LPS cases connected to observed extreme rainfall events, to investigate how sensitive the precipitation and runoff are to an idealized warmer and moister atmosphere. The ten cases are simulated with three different initial and lateral boundary conditions: the unperturbed control run, and two sets of perturbed runs where the atmospheric temperature is increased uniformly throughout the atmosphere, the specific humidity increased according to Clausius Clapeyron's relation, but the large-scale flow is unchanged. The difference between the control and perturbed simulations are mainly due to the imposed warming and feedback influencing the synoptic flow. The mean precipitation change with warming in the central Indian region is 18-20 %/K, with largest changes at the end of the LPS tracks. The LPS in the warmer runs are bringing more moisture further inland that is released as precipitation. In the perturbed runs the precipitation rate is increasing at all percentiles, and there is more frequent rainfall with very heavy intensities. This leads to a shift in which category that contributes most to the total precipitation: more of the precipitation is coming from the category with very heavy intensities. The runoff changes are similar to the precipitation changes, except the response in intensity of very heavy runoff, which is around twice the change in intensity of very heavy precipitation.

  9. High pressure liquid and gaseous oxygen impact sensitivity evaluation of materials for use at Kennedy Space Center

    NASA Technical Reports Server (NTRS)

    Bryan, C. J.

    1976-01-01

    The sensitivity of materials in contact with gaseous oxygen (GOX) or liquid oxygen (LOX) was examined. Specifically, the reactivity of materials when in contact with GOX or LOX if subjected to such stimuli as mechanical impact, adiabatic compression (pneumatic impact), or an electrical discharge in the form of a spark were examined. Generally, materials are more sensitive in gaseous oxygen than in liquid oxygen and impact sensitivity is known to increase with increasing pressure. Materials presently being used or considered for use in oxygen systems at KSC were evaluated. Results are given in tabular form.

  10. Gecko Adhesion on Wet and Dry Patterned Substrates

    PubMed Central

    Stark, Alyssa Y.; Palecek, Amanda M.; Argenbright, Clayton W.; Bernard, Craig; Brennan, Anthony B.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2015-01-01

    Perhaps one of the most astounding characteristics of the gecko adhesive system is its versatility. Geckos can locomote across complex substrates in a variety of conditions with apparent ease. In contrast, many of our synthetic pressure sensitive adhesives fail on substrates that are dirty, wet or rough. Although many studies have investigated the effect of environmental challenges on performance, the interaction of multiple, potentially compromising variables is studied less often. Here we focus on substrate structure and surface water, both of which are highly relevant to the biological system and to synthetic design. To do this we utilized a highly controlled, patterned substrate (Sharklet®, by Sharklet® Technologies Inc.). This allowed us to test independently and jointly the effects of reduced surface area substrates, with a defined pattern, on adhesion in both air and water. Our results show that adhesion is not significantly impaired in air, whereas surface area and pattern significantly affect adhesion in water. These findings highlight the need to study multiple parameters that are relevant to the gecko adhesive system to further improve our understanding of the biological system and to design better, more versatile synthetics. PMID:26696412

  11. Gecko Adhesion on Wet and Dry Patterned Substrates.

    PubMed

    Stark, Alyssa Y; Palecek, Amanda M; Argenbright, Clayton W; Bernard, Craig; Brennan, Anthony B; Niewiarowski, Peter H; Dhinojwala, Ali

    2015-01-01

    Perhaps one of the most astounding characteristics of the gecko adhesive system is its versatility. Geckos can locomote across complex substrates in a variety of conditions with apparent ease. In contrast, many of our synthetic pressure sensitive adhesives fail on substrates that are dirty, wet or rough. Although many studies have investigated the effect of environmental challenges on performance, the interaction of multiple, potentially compromising variables is studied less often. Here we focus on substrate structure and surface water, both of which are highly relevant to the biological system and to synthetic design. To do this we utilized a highly controlled, patterned substrate (Sharklet®, by Sharklet® Technologies Inc.). This allowed us to test independently and jointly the effects of reduced surface area substrates, with a defined pattern, on adhesion in both air and water. Our results show that adhesion is not significantly impaired in air, whereas surface area and pattern significantly affect adhesion in water. These findings highlight the need to study multiple parameters that are relevant to the gecko adhesive system to further improve our understanding of the biological system and to design better, more versatile synthetics. PMID:26696412

  12. Squeeze elastic deformation and contact area of a rubber adhesive

    NASA Astrophysics Data System (ADS)

    Tordjeman, P.; Papon, E.; Villenave, J.-J.

    2000-12-01

    New experimental results show that the tack energy of a nonstringing rubber adhesive is proportional to the square function of the contact area. However, this area seems only to be controlled by the contact force and the thickness of the adhesive. A study of how the contact area depends on physical parameters is of great interest for the modeling of the tack properties of pressure-sensitive adhesives (PSAs). With this objective, we give a mechanical analysis of the tack test in the framework of elasticity. This analysis leads to an analytical expression of force versus thickness of material that is in agreement with the experimental data. Based on this mechanical analysis, a model is proposed to take into account the dependence of the contact area with the contact force and the adhesive thickness. This model is based on the idea that, in confined geometry, the adhesive behaves like an elastic solid and the contact area is a function of the elastic squeeze deformation close to the probe surface. The confrontation with experimental results is good and shows the relevance of this approach. Finally, the model underlines the importance of the roughness, the thickness and the Young's modulus of the adhesive according to the experimental results.

  13. MiR-138 and MiR-135 directly target focal adhesion kinase, inhibit cell invasion, and increase sensitivity to chemotherapy in cancer cells.

    PubMed

    Golubovskaya, Vita M; Sumbler, Brittany; Ho, Baotran; Yemma, Michael; Cance, William G

    2014-01-01

    Focal Adhesion Kinase is a 125 kDa non-receptor kinase and overexpressed in many types of tumors. Recently, short noncoding RNAs, called microRNAs have been discovered as regulators of gene expression mainly through binding to the untranslated region (UTR) of mRNA. In this report we show that MiR-138 and MiR-135 down-regulated FAK expression in cancer cells. MiR-138 and MiR-135 inhibited FAK protein expression in different cancer cell lines. The computer analysis of 3'FAK-untranslated region (FAKUTR) identified one conserved MiR-138 binding site (CACCAGCA) at positions 3514-3521 and one conserved MiR-135 (AAGCCAU) binding site at positions 4278-4284 in the FAK-UTR. By a dual-luciferase assay we demonstrate that MiR-138 and MiR-135 directly bound the FAK untranslated region using FAK-UTR-Target (FAK-UTR) luciferase plasmid and inhibited its luciferase activity. The sitedirected mutagenesis of the MiR-138 and MiR-135 binding sites in the FAK-UTR abrogated MiR-138 and MiR-135-directed inhibition of FAK-UTR. Real-time PCR demonstrated that cells transfected with MiR-138 and MiR-135 expressed decreased FAK mRNA levels. Moreover, stable expression of MiR-138 and MiR-135 in 293 and HeLa cells decreased cell invasion and increased sensitivity to 5- fluorouracil (5-FU), FAK inhibitor, Y15, and doxorubicin. In addition, MiR-138 significantly decreased 293 xenograft tumor growth in vivo. This is the first report on regulation of FAK expression by MiR-135 and MiR138 that affected invasion, drug sensitivity, and tumor growth in cancer cells, which is important to the development of FAK-targeted therapeutics and understanding their novel regulations and functions. PMID:23438844

  14. A strong and stretchable self-healing film with self-activated pressure sensitivity for potential artificial skin applications

    PubMed Central

    Hou, Chengyi; Huang, Tao; Wang, Hongzhi; Yu, Hao; Zhang, Qinghong; Li, Yaogang

    2013-01-01

    Artificial skin, which mimics the functions of natural skin, will be very important in the future for robots used by humans in daily life. However, combining skin's pressure sensitivity and mechanical self-healing properties in a man-made material remains a challenging task. Here, we show that graphene and polymers can be integrated into a thin film which mimics both the mechanical self-healing and pressure sensitivity behavior of natural skin without any external power supply. Its ultimate strain and tensile strength are even two and ten times larger than the corresponding values of human skin, respectively. It also demonstrates highly stable sensitivity to a very light touch (0.02 kPa), even in bending or stretching states. PMID:24190511

  15. Effect of Trigger Sensitivity on Redistribution of Ventilation During Pressure Support Ventilation Detected by Electrical Impedance Tomography

    PubMed Central

    Radke, Oliver C.; Schneider, Thomas; Vogel, Elisabeth; Koch, Thea

    2015-01-01

    Background: In supine position, pressure support ventilation causes a redistribution of ventilation towards the ventral regions of the lung. Theoretically, a less sensitive support trigger would cause the patient to breathe more actively, potentially attenuating the effect of positive pressure ventilation. Objectives: To quantify the effect of trigger setting, we assessed redistribution of ventilation during pressure support ventilation (PSV) using electrical impedance tomography (EIT). Patients and Methods: With approval from the local ethics committee, six orthopedic patients were enrolled. All patients had general anesthesia with a laryngeal mask airway and a standardized anesthetic regimen (sufentanil, propofol and sevoflurane). Pressure support trigger settings varied between 2 and 15 L/minute and compared to unassisted spontaneous breathing. From EIT data, the center of ventilation (COV), the fraction of the total ventilation per region of interest (ROI) and intratidal gas distribution were calculated. Results: At all trigger settings, pressure support ventilation caused a significant ventral shift of the center of ventilation compared with during spontaneous breathing, confirmed by the analysis by regions of interest. During spontaneous breathing, COV was not different from baseline values obtained before induction of anesthesia. During PSV, the intratidal regional gas distribution (ITV-analysis) revealed subtle changes during the early inspiratory phase not detected by the COV-analysis. Conclusions: Pressure support ventilation, but not spontaneous breathing, induces a significant redistribution of ventilation towards the ventral region. The sensitivity of the support trigger appears to influence the distribution of ventilation only during the early phase of inspiration. PMID:26478865

  16. An Experimental Evaluation of HVAC-Grade Carbon-Dioxide Sensors: Part 3, Humidity, Temperature, and Pressure Sensitivity Test Results

    SciTech Connect

    Shrestha, Som S; Maxwell, Dr. Gregory

    2010-01-01

    This is the third paper in a four-part series reporting on the test and evaluation of typical carbon-dioxide sensors used in building HVAC applications. Fifteen models of NDIR HVAC-grade CO2 sensors were tested and evaluated to determine the humidity, temperature, and pressure sensitivity of the sensors. This paper reports the performance of the sensors at various relative humidity, temperature, and pressure levels common to building HVAC applications and provides a comparison with manufacturer specifications. Among the 15 models tested, eight models have a single-lamp, single-wavelength configuration, four models have a dual-lamp, single-wavelength configuration, and three models have a single-lamp, dual-wavelength configuration. The sensors were tested in a chamber specifically fabricated for this research. A description of the apparatus and the method of test are described in Part 1 (Shrestha and Maxwell 2009). The test result showed a wide variation in humidity, temperature, and pressure sensitivity of CO2 sensors among manufacturers. In some cases, significant variations in sensor performance exist between sensors of the same model. Even the natural variation in relative humidity could significantly vary readings of some CO2 sensor readings. The effects of temperature and pressure variation on NDIR CO2 sensors are unavoidable without an algorithm to compensate for the changes. For the range of temperature and pressure variation in an air-conditioned space, the effect of pressure variation is more significant compared to the effect of temperature variation.

  17. ATP-Sensitive Potassium (KATP) Channel Openers Diazoxide and Nicorandil Lower Intraocular Pressure In Vivo

    PubMed Central

    Chowdhury, Uttio Roy; Holman, Bradley H.; Fautsch, Michael P.

    2013-01-01

    Purpose. To evaluate the expression of ATP-sensitive potassium (KATP) channel subunits and study the effect of KATP channel openers diazoxide and nicorandil on intraocular pressure (IOP) in an in vivo mouse model. Methods. Expression of KATP channel subunits in normal C57BL/6 mouse eyes was studied by immunohistochemistry and confocal microscopy. Wild-type C57BL/6 mice were treated with KATP channel openers diazoxide (n = 10) and nicorandil (n = 10) for 14 days. Similar treatments with diazoxide were performed on Kir6.2(−/−) mice (n = 10). IOP was recorded with a handheld tonometer 1 hour, 4 hours, and 23 hours following daily treatment. Posttreatment histology was examined by light and transmission electron microscopy. Results. The KATP channel subunits SUR2B, Kir6.1, and Kir6.2 were identified in all tissues within mouse eyes. Treatment with diazoxide in wild-type mice decreased IOP by 21.5 ± 3.2% with an absolute IOP reduction of 3.9 ± 0.6 mm Hg (P = 0.002). Nicorandil also decreased IOP (18.9 ± 1.8%) with an absolute IOP reduction of 3.4 ± 0.4 mm Hg (P = 0.002). Treatment with diazoxide in Kir6.2(−/−) mice had no effect on IOP. No morphological abnormalities were observed in diazoxide- or nicorandil-treated eyes. Conclusions. KATP channel openers diazoxide and nicorandil are effective regulators of IOP in mouse eyes. Kir6.2 appears to be a major KATP channel subunit through which IOP is lowered following treatment with diazoxide. PMID:23778875

  18. Comparison of high pressure-induced dissociation of single-stranded DNA-binding protein (SSB) from high pressure-sensitive and high pressure-adapted marine Shewanella species.

    PubMed

    Chilukuri, Lakshmi N; Bartlett, Douglas H; Fortes, P A George

    2002-10-01

    The effects of hydrostatic pressure on protein quaternary structure were compared for recombinant single-stranded DNA-binding protein (SSB) derived from piezosensitive, piezotolerant, and obligately piezophilic ("pressure-loving") marine Shewanella strains. The pressure-induced dissociation of the oligomeric SSB proteins was investigated using fluorescence anisotropy. The SSBs all exhibited striking similarity in the pressure-dependent behavior of the fluorescence intensity and emission spectrum as well as in their dissociation constants at atmospheric pressure. The free energies of subunit association into tetramers for all SSBs were between -27 and -30 kcal mol(-1). However, SSB from the piezosensitive Shewanella strain S. hanedai was more sensitive to pressure than that of the SSB proteins from the piezotolerant or piezophilic bacteria. The volume change of association obtained from the pressure dependence of dissociation at a fixed protein concentration (Delta V(p)) for SSB from S. hanedai was 394-402 ml mol(-1). The Delta V(p) values for SSB from the deeper-living Shewanellas were smaller and ranged from 253 to 307 ml mol(-1). Differences between the primary structures of the SSB proteins that could correlate with differences in sensitivity to pressure-induced dissociation were examined. PMID:12382113

  19. 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.

  20. JKR adhesion in cylindrical contacts

    NASA Astrophysics Data System (ADS)

    Sundaram, Narayan; Farris, T. N.; Chandrasekar, S.

    2012-01-01

    Planar JKR adhesive solutions use the half-plane assumption and do not permit calculation of indenter approach or visualization of adhesive force-displacement curves unless the contact is periodic. By considering a conforming cylindrical contact and using an arc crack analogy, we obtain closed-form indenter approach and load-contact size relations for a planar adhesive problem. The contact pressure distribution is also obtained in closed-form. The solutions reduce to known cases in both the adhesion-free and small-contact solution ( Barquins, 1988) limits. The cylindrical system shows two distinct regimes of adhesive behavior; in particular, contact sizes exceeding the critical (maximum) size seen in adhesionless contacts are possible. The effects of contact confinement on adhesive behavior are investigated. Some special cases are considered, including contact with an initial neat-fit and the detachment of a rubbery cylinder from a rigid cradle. A comparison of the cylindrical solution with the half-plane adhesive solution is carried out, and it indicates that the latter typically underestimates the adherence force. The cylindrical adhesive system is novel in that it possesses stable contact states that may not be attained even on applying an infinite load in the absence of adhesion.

  1. 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.

  2. Na+-sensitive elevation in blood pressure is ENaC independent in diet-induced obesity and insulin resistance.

    PubMed

    Nizar, Jonathan M; Dong, Wuxing; McClellan, Robert B; Labarca, Mariana; Zhou, Yuehan; Wong, Jared; Goens, Donald G; Zhao, Mingming; Velarde, Nona; Bernstein, Daniel; Pellizzon, Michael; Satlin, Lisa M; Bhalla, Vivek

    2016-05-01

    The majority of patients with obesity, insulin resistance, and metabolic syndrome have hypertension, but the mechanisms of hypertension are poorly understood. In these patients, impaired sodium excretion is critical for the genesis of Na(+)-sensitive hypertension, and prior studies have proposed a role for the epithelial Na(+) channel (ENaC) in this syndrome. We characterized high fat-fed mice as a model in which to study the contribution of ENaC-mediated Na(+) reabsorption in obesity and insulin resistance. High fat-fed mice demonstrated impaired Na(+) excretion and elevated blood pressure, which was significantly higher on a high-Na(+) diet compared with low fat-fed control mice. However, high fat-fed mice had no increase in ENaC activity as measured by Na(+) transport across microperfused cortical collecting ducts, electrolyte excretion, or blood pressure. In addition, we found no difference in endogenous urinary aldosterone excretion between groups on a normal or high-Na(+) diet. High fat-fed mice provide a model of metabolic syndrome, recapitulating obesity, insulin resistance, impaired natriuresis, and a Na(+)-sensitive elevation in blood pressure. Surprisingly, in contrast to previous studies, our data demonstrate that high fat feeding of mice impairs natriuresis and produces elevated blood pressure that is independent of ENaC activity and likely caused by increased Na(+) reabsorption upstream of the aldosterone-sensitive distal nephron. PMID:26841823

  3. Design, fabrication and characterization of a high-sensitivity pressure sensor based on nano-polysilicon thin film transistors

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaofeng; Yu, Yang; Li, Dandan; Wen, Dianzhong

    2015-12-01

    Based on the nano-polysilicon thin film transistors (TFTs), a high-sensitivity pressure sensor was designed and fabricated in this paper. The pressure sensing element is composed of a Wheatstone bridge with four nano-polysilicon TFTs designed on different positions of the square silicon diaphragm. Via taking the four channel resistors of the TFTs as piezoresistors, the measurement to the external pressure can be realized according to the piezoresistive effects of channel layer. Through adopting complementary metal oxide semiconductor (CMOS) technology and micro-electromechanical system (MEMS) technology, the chips of sensor were fabricated on <100 > orientation silicon wafer with a high resistivity. At room temperature, when applying a voltage 5.0 V to the Wheatstone bridge, the full scale (100 kPa) output voltage and the sensitivity of the sensor with 35 μm-thick silicon diaphragm are 267 mV and 2.58 mV/kPa, respectively. The experimental results show that the pressure sensors can achieve a much higher sensitivity.

  4. Investigation of transverse jet injections in a supersonic crossflow using fast-responding pressure-sensitive paint

    NASA Astrophysics Data System (ADS)

    Crafton, Jim; Forlines, Alan; Palluconi, Steve; Hsu, Kuang-Yu; Carter, Campbell; Gruber, Mark

    2015-02-01

    Traditional pressure-sensitive paint (PSP) systems can provide data with high spatial resolution; however, the bandwidth is limited to a few Hz by the response time of the paint. Fast-responding paints have demonstrated response times of up to 100 kHz. Ultra-bright LEDs and fast-framing cameras combined with a porous polymer PSP can be used to produce a system capable of both high spatial resolution and high temporal bandwidth. Measurements of mean and unsteady pressure have been acquired on an experimental setup composed of a Mach-2 channel flow with transverse jet injection. The unsteady pressure data clearly resolve structures not present in the mean pressure data, including multiple lambda shocks upstream of a strong bow shock, high-frequency perturbations in the location of these shocks, and significant deformations of the bow shock structure. Time series of data can be extracted at each pixel, and the spectral content and phase relationship of the flow can be presented as maps of pressure fluctuations at specific frequencies or as correlation coefficients between a control point and the remaining flow. This type of map can be created using arrays of fast pressure transducers; here, we present data representing an array of over 26,000 fast pressure transducers.

  5. Application of fast-responding pressure-sensitive paint to a hemispherical dome in unsteady transonic flow

    NASA Astrophysics Data System (ADS)

    Fang, Shuo; Disotell, Kevin J.; Long, Samuel R.; Gregory, James W.; Semmelmayer, Frank C.; Guyton, Robert W.

    2011-06-01

    The current work focuses on the development and application of fast-responding polymer/ceramic pressure-sensitive paint (PSP) as an advanced surface pressure measurement technique for unsteady flow fields in large-scale wind tunnels. To demonstrate the unsteady PSP technique, the unsteady surface pressure distribution over a hemispherical dome placed in the United States Air Force Research Laboratory's Trisonic Gasdynamics Facility (TGF) was studied by phase-locking to the characteristic frequency in the flow caused by an unsteady separated shear layer shed from the dome. The wind tunnel was operated at stagnation pressures of 23.92 and 71.84 kPa, with the test section flow at Mach 0.6. Under the two operating conditions, the predominant shear layer frequency was measured to be 272 and 400 Hz, respectively. The quasi-periodic shear layer frequency enabled a phase-averaged method to be employed for capturing the unsteady shock motion on the hemisphere. Unsteady pressure data resulting from this technique are shown to correlate well with measurements acquired by conventional measurement techniques. Measurement uncertainty in the phase-averaging technique will be discussed. To address measurement uncertainties from temperature sensitivity and model movement, a new implementation of an AC-coupled data representation is offered.

  6. Highly Sensitive, Flexible, and Wearable Pressure Sensor Based on a Giant Piezocapacitive Effect of Three-Dimensional Microporous Elastomeric Dielectric Layer.

    PubMed

    Kwon, Donguk; Lee, Tae-Ik; Shim, Jongmin; Ryu, Seunghwa; Kim, Min Seong; Kim, Seunghwan; Kim, Taek-Soo; Park, Inkyu

    2016-07-01

    We report a flexible and wearable pressure sensor based on the giant piezocapacitive effect of a three-dimensional (3-D) microporous dielectric elastomer, which is capable of highly sensitive and stable pressure sensing over a large tactile pressure range. Due to the presence of micropores within the elastomeric dielectric layer, our piezocapacitive pressure sensor is highly deformable by even very small amounts of pressure, leading to a dramatic increase in its sensitivity. Moreover, the gradual closure of micropores under compression increases the effective dielectric constant, thereby further enhancing the sensitivity of the sensor. The 3-D microporous dielectric layer with serially stacked springs of elastomer bridges can cover a much wider pressure range than those of previously reported micro-/nanostructured sensing materials. We also investigate the applicability of our sensor to wearable pressure-sensing devices as an electronic pressure-sensing skin in robotic fingers as well as a bandage-type pressure-sensing device for pulse monitoring at the human wrist. Finally, we demonstrate a pressure sensor array pad for the recognition of spatially distributed pressure information on a plane. Our sensor, with its excellent pressure-sensing performance, marks the realization of a true tactile pressure sensor presenting highly sensitive responses to the entire tactile pressure range, from ultralow-force detection to high weights generated by human activity. PMID:27286001

  7. 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

  8. Heightened cold pain and pressure pain sensitivity in young female adults with moderate-to-severe menstrual pain.

    PubMed

    Slater, Helen; Paananen, Markus; Smith, Anne J; OʼSullivan, Peter; Briggs, Andrew M; Hickey, Martha; Mountain, Jenny; Karppinen, Jaro; Beales, Darren

    2015-12-01

    This study investigated the association between menstrual pain severity and psychophysical measures of cold and pressure pain sensitivity. A cross-sectional design was used with young women (n = 432) from the Western Australian Pregnancy Cohort (Raine) Study. Menstrual pain severity and oral contraception use was obtained from questionnaires at 20 and 22-year follow-ups. A visual analog scale (VAS; range from 0 [none] to 10 [unbearable]) was used to measure menstrual pain severity at both 20 and 22 years over the 3-year period, with 3 groups created: (1) no pain or mild pain (VAS 0-3), (2) at least moderate pain at a minimum of 1 of the 2 time points (hereafter named "mixed)", and (3) severe pain (VAS 8-10). Cold pain sensitivity (dorsal wrist) and pressure pain sensitivity (lumbar spine, upper trapezius, dorsal wrist, and tibialis anterior) were assessed using standardised quantitative sensory testing protocols. Confounding variables included number of musculoskeletal pain sites, oral contraceptive use, smoking, physical activity, body mass index, psychological distress, and sleep. Severe menstrual pain and mixed menstrual pain were positively associated with heightened cold pain sensitivity (distant from menstrual pain referral site) and pressure pain sensitivity (local to menstrual pain referral site). These associations remained significant after adjusting for potential confounding variables including multisite musculoskeletal pain. Our findings suggest peripheral and central neurophysiological mechanisms contributing to heightened pain sensitivity in young women with moderate and severe menstrual pain. These data highlight the need for innovative management approaches to attenuate the negative impact of severe menstrual pain in young women. PMID:26262827

  9. Morning blood pressure surge is associated with arterial stiffness and sympathetic baroreflex sensitivity in hypertensive seniors

    PubMed Central

    Okada, Yoshiyuki; Galbreath, M. Melyn; Shibata, Shigeki; Jarvis, Sara S.; Bivens, Tiffany B.; Vongpatanasin, Wanpen; Levine, Benjamin D.

    2013-01-01

    Morning blood pressure (BP) surge is considered to be an independent risk factor for cardiovascular diseases. We tested the hypothesis that increased large-artery stiffness and impaired sympathetic baroreflex sensitivity (BRS) contribute to augmented morning surge in elderly hypertensive subjects. Morning surge was assessed as morning systolic BP averaged for 2 h just after waking up minus minimal sleeping systolic BP by using ambulatory BP monitoring (ABPM) in 40 untreated hypertensive [68 ± 1 (SE) yr] and 30 normotensive (68 ± 1 yr) subjects. Beat-by-beat finger BP and muscle sympathetic nerve activity (MSNA) were recorded in the supine position and at 60° upright tilt. We assessed arterial stiffness with carotid-to-femoral pulse wave velocity (cfPWV) and sympathetic BRS during spontaneous breathing. Awake and asleep ABPM-BPs and morning surge were higher in hypertensive than normotensive subjects (all P < 0.001). cfPWV was higher (P = 0.002) and sympathetic BRS was lower (P = 0.096) in hypertensive than normotensive subjects. Hypertensive subjects with morning surge ≥35 mmHg (median value) had higher cfPWV (11.9 ± 0.5 vs. 9.9 ± 0.4 m/s, P = 0.002) and lower sympathetic BRS (supine: −2.71 ± 0.25 vs. −3.73 ± 0.29, P = 0.011; upright: −2.62 ± 0.22 vs. −3.51 ± 0.35 bursts·100 beats−1·mmHg−1, P = 0.052) than those with morning surge <35 mmHg. MSNA indices were similar between groups (all P > 0.05), while upright total peripheral resistance was higher in hypertensive subjects with greater morning surge than those with lesser morning surge (P = 0.050). Morning surge was correlated positively with cfPWV (r = 0.59, P < 0.001) and negatively with sympathetic BRS (r = 0.51, P < 0.001) in hypertensive subjects only. Thus, morning BP surge is associated with arterial stiffness and sympathetic BRS, as well as vasoreactivity during orthostasis in hypertensive seniors. PMID:23832695

  10. Differential Sensitivity Theory applied to the MESA code for high pressure interactions

    NASA Astrophysics Data System (ADS)

    Maudlin, P. J.; Henninger, R. J.; Harstad, E. N.

    A technique called Differential Sensitivity Theory (DST) is applied to the system of equations solved by the MESA hydrocode. DST uses adjoint techniques to determine exact sensitivity derivatives, i.e., if R is a calculational result of interest (response R) and alpha(sub i) is a calculational input (parameter alpha(sub i)), then (partial derivative)R/(partial derivative)alpha(sub i) is defined as the sensitivity. The advantage of using DST is that for an n-parameter problem all n sensitivities can be obtained by integrating the solutions from only two calculations, a MESA calculation and its corresponding adjoint calculation using an Adjoint Continuum Mechanics code (ACM). This work describes the derivation and solution of the appropriate set of adjoint and sensitivity equations for the purpose of computing sensitivities for high-rate two-dimensional, multi-component, high deformation problems. As an example, results are presented for a flyer plate problem.

  11. Differential Sensitivity Theory applied to the MESA code for high pressure interactions

    SciTech Connect

    Maudlin, P.J.; Henninger, R.J.; Harstad, E.N.

    1993-07-01

    A technique called Differential Sensitivity Theory (DST) is applied to the system of equations solved by the MESA hydrocode. DST uses adjoint techniques to determine exact sensitivity derivatives, i.e., if R is a calculational result of interest (response R) and {alpha}{sub i} is a calculational input (parameter {alpha}{sub i}), then {partial_derivative}R/{partial_derivative}{alpha}{sub i} is defined as the sensitivity. The advantage of using DST is that for an n-parameter problem all n sensitivities can be obtained by integrating the solutions from only two calculations, a MESA calculation and its corresponding adjoint calculation using an Adjoint Continuum Mechanics code (ACM). This work describes the derivation and solution of the appropriate set of adjoint and sensitivity equations for the purpose of computing sensitivities for high-rate two-dimensional, multi-component, high deformation problems. As an example, results are presented for a flyer plate problem.

  12. Sensitive low-pressure relief valve has positive seating against leakage

    NASA Technical Reports Server (NTRS)

    1964-01-01

    A pilot-operated relief valve which provides positive seating against leakage in cryogenic systems is described. The principal advantage is that the pilot poppet is unaffected by variations in control pressures in the pilot cavity, and results in a more accurate sensing of inlet pressure conditions.

  13. Wind Tunnel Application of a Pressure-Sensitive Paint Technique to a Faceted Missile Model at Subsonic and Transonic Speeds

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.

    2004-01-01

    A pressure-sensitive paint (PSP) technique was applied in a wind tunnel experiment in the NASA Langley Research Center 8-Foot Transonic Pressure Tunnel to quantify the vortex-induced surface static pressures on a slender, faceted missile model at subsonic and transonic speeds. Global PSP calibrations were obtained using an in-situ method featuring the simultaneous electronically-scanned pressures (ESP) measurements. Both techniques revealed the significant influence leading-edge vortices on the surface pressure distributions. The mean error in the PSP measurements relative to the ESP data was approximately 0.6 percent at M(sub infinity)=0.70 and 2.6 percent at M(sub infinity)=0.90 and 1.20. The vortex surface pressure signatures obtained from the PSP and ESP techniques were correlated with the off-surface vortex cross-flow structures obtained using a laser vapor screen (LVS) flow visualization technique. The on-surface and off-surface techniques were complementary, since each provided details of the vortex-dominated flow that were not clear or apparent in the other.

  14. Wind Tunnel Application of a Pressure-Sensitive Paint Technique to a Faceted Missile Model at Subsonic and Transonic Speeds

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.

    2004-01-01

    A pressure-sensitive paint (PSP) technique was applied in a wind tunnel experiment in the NASA Langley Research Center 8-Foot Transonic Pressure Tunnel to quantify the vortex-induced surface static pressures on a slender, faceted missile model at subsonic and transonic speeds. Satisfactory global calibrations of the PSP were obtained at =0.70, 0.90, and 1.20, angles of attack from 10 degrees to 20 degrees, and angles of sideslip of 0 and 2.5 degrees using an in-situ method featuring the simultaneous acquisition of electronically-scanned pressures (ESP) at 57 discrete locations on the model. Both techniques clearly revealed the significant influence on the surface pressure distributions of the vortices shed from the sharp, chine-like leading edges. The mean error in the PSP measurements relative to the ESP data was approximately 0.6 percent at M infinity =0.70 and 2.6 percent at M infinity =0.90 and 1.20. The vortex surface pressure signatures obtained from the PSP and ESP techniques were correlated with the off-surface vortex cross-flow structures obtained using a laser vapor screen (LVS) flow visualization technique. The on-surface and off-surface techniques were complementary, since each provided details of the vortex-dominated flow that were not clear or apparent in the other.

  15. Using Pressure- and Temperature-Sensitive Paint for Global Surface Pressure and Temperature Measurements on the Aft-Body of a Capsule Reentry Vehicle

    NASA Technical Reports Server (NTRS)

    Watkins, A. Neal; Buck, Gregory M.; Leighty, Bradley D.; Lipford, William E.; Oglesby, Donald M.

    2008-01-01

    Pressure Sensitive Paint (PSP) and Temperature Sensitive Paint (TSP) were used to visualize and quantify the surface interactions of reaction control system (RCS) jets on the aft body of capsule reentry vehicle shapes. The first model tested was an Apollo-like configuration and was used to focus primarily on the effects of the forward facing roll and yaw jets. The second model tested was an early Orion Crew Module configuration blowing only out of its forward-most yaw jet, which was expected to have the most intense aerodynamic heating augmentation on the model surface. This paper will present the results from the experiments, which show that with proper system design, both PSP and TSP are effective tools for studying these types of interaction in hypersonic testing environments.

  16. Improving the Sensitivity of Mass Spectrometry by Using a New Sheath Flow Electrospray Emitter Array at Subambient Pressures

    DOE PAGESBeta

    Cox, Jonathan T.; Marginean, Ioan; Kelly, Ryan T.; Smith, Richard D.; Tang, Keqi

    2014-03-28

    Arrays of chemically etched emitters with individualized sheath gas capillaries have been developed to enhance electrospray ionization (ESI) at subambient pressures. By including an emitter array in a subambient pressure ionization with nanoelectrospray (SPIN) source, ionization and transmission efficiency can be maximized allowing for increased sensitivity in mass spectrometric analyses. The SPIN source eliminates the major ion losses at conventional ESI-mass spectrometry (MS) interface by placing the emitter in the first vacuum region of the instrument. To facilitate stable electrospray currents in such conditions we have developed an improved emitter array with individualized sheath gas around each emitter. The utilitymore » of the new emitter arrays for generating stable multi-electrosprays at subambient pressures was probed by coupling the emitter array/SPIN source with a time of flight (TOF) mass spectrometer. The instrument sensitivity was compared between single emitter/SPIN-MS and multi-emitter/SPIN-MS configurations using an equimolar solution of 9 peptides. An increase in sensitivity correlative to the number of emitters in the array was observed.« less

  17. Improving the Sensitivity of Mass Spectrometry by Using a New Sheath Flow Electrospray Emitter Array at Subambient Pressures

    SciTech Connect

    Cox, Jonathan T.; Marginean, Ioan; Kelly, Ryan T.; Smith, Richard D.; Tang, Keqi

    2014-03-28

    Arrays of chemically etched emitters with individualized sheath gas capillaries have been developed to enhance electrospray ionization (ESI) at subambient pressures. By including an emitter array in a subambient pressure ionization with nanoelectrospray (SPIN) source, ionization and transmission efficiency can be maximized allowing for increased sensitivity in mass spectrometric analyses. The SPIN source eliminates the major ion losses at conventional ESI-mass spectrometry (MS) interface by placing the emitter in the first vacuum region of the instrument. To facilitate stable electrospray currents in such conditions we have developed an improved emitter array with individualized sheath gas around each emitter. The utility of the new emitter arrays for generating stable multi-electrosprays at subambient pressures was probed by coupling the emitter array/SPIN source with a time of flight (TOF) mass spectrometer. The instrument sensitivity was compared between single emitter/SPIN-MS and multi-emitter/SPIN-MS configurations using an equimolar solution of 9 peptides. An increase in sensitivity correlative to the number of emitters in the array was observed.

  18. Static and Wind-on Performance of Polymer-Based Pressure-Sensitive Paints Using Platinum and Ruthenium as the Luminophore.

    PubMed

    Lo, Kin Hing; Kontis, Konstantinos

    2016-01-01

    An experimental study has been conducted to investigate the static and wind-on performance of two in-house-developed polymer-based pressure-sensitive paints. Platinum tetrakis (pentafluorophenyl) porphyrin and tris-bathophenanthroline ruthenium II are used as the luminophores of these two polymer-based pressure-sensitive paints. The pressure and temperature sensitivity and the photo-degradation rate of these two pressure-sensitive paints have been investigated. In the wind tunnel test, it was observed that the normalised intensity ratio of both polymer-based pressure-sensitive paints being studied decreases with increasing the number of wind tunnel runs. The exact reason that leads to the occurrence of this phenomenon is unclear, but it is deduced that the luminophore is either removed or deactivated by the incoming flow during a wind tunnel test. PMID:27128913

  19. Static and Wind-on Performance of Polymer-Based Pressure-Sensitive Paints Using Platinum and Ruthenium as the Luminophore

    PubMed Central

    Lo, Kin Hing; Kontis, Konstantinos

    2016-01-01

    An experimental study has been conducted to investigate the static and wind-on performance of two in-house-developed polymer-based pressure-sensitive paints. Platinum tetrakis (pentafluorophenyl) porphyrin and tris-bathophenanthroline ruthenium II are used as the luminophores of these two polymer-based pressure-sensitive paints. The pressure and temperature sensitivity and the photo-degradation rate of these two pressure-sensitive paints have been investigated. In the wind tunnel test, it was observed that the normalised intensity ratio of both polymer-based pressure-sensitive paints being studied decreases with increasing the number of wind tunnel runs. The exact reason that leads to the occurrence of this phenomenon is unclear, but it is deduced that the luminophore is either removed or deactivated by the incoming flow during a wind tunnel test. PMID:27128913

  20. Investigation of three-dimensional dynamic stall on an airfoil using fast-response pressure-sensitive paint

    NASA Astrophysics Data System (ADS)

    Gardner, A. D.; Klein, C.; Sachs, W. E.; Henne, U.; Mai, H.; Richter, K.

    2014-09-01

    Dynamic stall on a pitching OA209 airfoil in a wind tunnel is investigated at Mach 0.3 and 0.5 using high-speed pressure-sensitive paint (PSP) and pressure measurements. At Mach 0.3, the dynamic stall vortex was observed to propagate faster at the airfoil midline than at the wind-tunnel wall, resulting in a "bowed" vortex shape. At Mach 0.5, shock-induced stall was observed, with initial separation under the shock foot and subsequent expansion of the separated region upstream, downstream and along the breadth of the airfoil. No dynamic stall vortex could be observed at Mach 0.5. The investigation of flow control by blowing showed the potential advantages of PSP over pressure transducers for a complex three-dimensional flow.

  1. Sensitive Measurement of Trace Mercury Using Low Pressure Laser-Induced Plasma

    NASA Astrophysics Data System (ADS)

    Wang, Zhenzhen; Deguchi, Yoshihiro; Kuwahara, Masakazu; Zhang, Xiaobo; Yan, Junjie; Liu, Jiping

    2013-11-01

    The emission of trace heavy metals, such as mercury (Hg), from power plants and other industries is a severe environmental problem concerning the public health. The laser-induced plasma technique was employed to measure Hg under various conditions, which reveals several merits of this method at low pressure. The main interferences of laser-induced breakdown spectroscopy (LIBS), which include the black-body-like emission from plasma itself and coexisting molecular and atomic emissions, decreased significantly using low pressure laser-induced plasma. Under low pressure conditions, Hg signal was rather clear without serious influence even if there is no delay time from the laser irradiation, which means the gated detection device is not necessary. This method featured the detection limit of 0.3 ppm at pressure 700 Pa. Additionally, the feasible of this method in real applications was demonstrated by measuring Hg in combustion gas which performed preferable results.

  2. Frog tongue acts as muscle-powered adhesive tape.

    PubMed

    Kleinteich, Thomas; Gorb, Stanislav N

    2015-09-01

    Frogs are well known to capture fast-moving prey by flicking their sticky tongues out of the mouth. This tongue projection behaviour happens extremely fast which makes frog tongues a biological high-speed adhesive system. The processes at the interface between tongue and prey, and thus the mechanism of adhesion, however, are completely unknown. Here, we captured the contact mechanics of frog tongues by filming tongue adhesion at 2000 frames per second through an illuminated glass. We found that the tongue rolls over the target during attachment. However, during the pulling phase, the tongue retractor muscle acts perpendicular to the target surface and thus prevents peeling during tongue retraction. When the tongue detaches, mucus fibrils form between the tongue and the target. Fibrils commonly occur in pressure-sensitive adhesives, and thus frog tongues might be a biological analogue to these engineered materials. The fibrils in frog tongues are related to the presence of microscopic papillae on the surface. Together with a layer of nanoscale fibres underneath the tongue epithelium, these surface papillae will make the tongue adaptable to asperities. For the first time, to the best of our knowledge, we are able to integrate anatomy and function to explain the processes during adhesion in frog tongues. PMID:26473054

  3. Frog tongue acts as muscle-powered adhesive tape

    PubMed Central

    Kleinteich, Thomas; Gorb, Stanislav N.

    2015-01-01

    Frogs are well known to capture fast-moving prey by flicking their sticky tongues out of the mouth. This tongue projection behaviour happens extremely fast which makes frog tongues a biological high-speed adhesive system. The processes at the interface between tongue and prey, and thus the mechanism of adhesion, however, are completely unknown. Here, we captured the contact mechanics of frog tongues by filming tongue adhesion at 2000 frames per second through an illuminated glass. We found that the tongue rolls over the target during attachment. However, during the pulling phase, the tongue retractor muscle acts perpendicular to the target surface and thus prevents peeling during tongue retraction. When the tongue detaches, mucus fibrils form between the tongue and the target. Fibrils commonly occur in pressure-sensitive adhesives, and thus frog tongues might be a biological analogue to these engineered materials. The fibrils in frog tongues are related to the presence of microscopic papillae on the surface. Together with a layer of nanoscale fibres underneath the tongue epithelium, these surface papillae will make the tongue adaptable to asperities. For the first time, to the best of our knowledge, we are able to integrate anatomy and function to explain the processes during adhesion in frog tongues. PMID:26473054

  4. Surface characterization and adhesion of oxygen plasma-modified LARC-TPI

    NASA Technical Reports Server (NTRS)

    Chin, J. W.; Wightman, J. P.

    1992-01-01

    LARC-TPI, an aromatic thermoplastic polyimide, was exposed to an oxygen plasma as a surface pretreatment for adhesive bonding. Chemical and physical changes which occurred in the polyimide surface as a result of the plasma treatment were investigated using X-ray photoelectron spectroscopy (XPS), infrared reflection-absorption spectroscopy (IR-RAS), contact-angle analysis, ellipsometry, and high resolution SEM. A 180-deg peel test with an acrylate-based pressure sensitive adhesive as a flexible adherent was utilized to study the interactions of the plasma-treated polyimide surface with other polymeric materials. The surface characterization and adhesion testing results showed that the oxygen plasma treatment, while creating a more hydrophilic, polar surface, also caused chain scission, resulting in the formation of a weak boundary layer which inhibited adhesion.

  5. P2RX7 sensitizes Mac-1/ICAM-1-dependent leukocyte-endothelial adhesion and promotes neurovascular injury during septic encephalopathy

    PubMed Central

    Wang, Huan; Hong, Ling-Juan; Huang, Ji-Yun; Jiang, Quan; Tao, Rong-Rong; Tan, Chao; Lu, Nan-Nan; Wang, Cheng-Kun; Ahmed, Muhammad M; Lu, Ying-Mei; Liu, Zhi-Rong; Shi, Wei-Xing; Lai, En-Yin; Wilcox, Christopher S; Han, Feng

    2015-01-01

    Septic encephalopathy (SE) is a critical factor determining sepsis mortality. Vascular inflammation is known to be involved in SE, but the molecular events that lead to the development of encephalopathy remain unclear. Using time-lapse in vivo two-photon laser scanning microscopy, we provide the first direct evidence that cecal ligation and puncture in septic mice induces microglial trafficking to sites adjacent to leukocyte adhesion on inflamed cerebral microvessels. Our data further demonstrate that septic injury increased the chemokine CXCL1 level in brain endothelial cells by activating endothelial P2RX7 and eventually enhanced the binding of Mac-1 (CD11b/CD18)-expressing leukocytes to endothelial ICAM-1. In turn, leukocyte adhesion upregulated endothelial CX3CL1, thereby triggering microglia trafficking to the injured site. The sepsis-induced increase in endothelial CX3CL1 was abolished in CD18 hypomorphic mutant mice. Inhibition of the P2RX7 pathway not only decreased endothelial ICAM-1 expression and leukocyte adhesion but also prevented microglia overactivation, reduced brain injury, and consequently doubled the early survival of septic mice. These results demonstrate the role of the P2RX7 pathway in linking neurovascular inflammation to brain damage in vivo and provide a rationale for targeting endothelial P2RX7 for neurovascular protection during SE. PMID:25998681

  6. P2RX7 sensitizes Mac-1/ICAM-1-dependent leukocyte-endothelial adhesion and promotes neurovascular injury during septic encephalopathy.

    PubMed

    Wang, Huan; Hong, Ling-Juan; Huang, Ji-Yun; Jiang, Quan; Tao, Rong-Rong; Tan, Chao; Lu, Nan-Nan; Wang, Cheng-Kun; Ahmed, Muhammad M; Lu, Ying-Mei; Liu, Zhi-Rong; Shi, Wei-Xing; Lai, En-Yin; Wilcox, Christopher S; Han, Feng

    2015-06-01

    Septic encephalopathy (SE) is a critical factor determining sepsis mortality. Vascular inflammation is known to be involved in SE, but the molecular events that lead to the development of encephalopathy remain unclear. Using time-lapse in vivo two-photon laser scanning microscopy, we provide the first direct evidence that cecal ligation and puncture in septic mice induces microglial trafficking to sites adjacent to leukocyte adhesion on inflamed cerebral microvessels. Our data further demonstrate that septic injury increased the chemokine CXCL1 level in brain endothelial cells by activating endothelial P2RX7 and eventually enhanced the binding of Mac-1 (CD11b/CD18)-expressing leukocytes to endothelial ICAM-1. In turn, leukocyte adhesion upregulated endothelial CX3CL1, thereby triggering microglia trafficking to the injured site. The sepsis-induced increase in endothelial CX3CL1 was abolished in CD18 hypomorphic mutant mice. Inhibition of the P2RX7 pathway not only decreased endothelial ICAM-1 expression and leukocyte adhesion but also prevented microglia overactivation, reduced brain injury, and consequently doubled the early survival of septic mice. These results demonstrate the role of the P2RX7 pathway in linking neurovascular inflammation to brain damage in vivo and provide a rationale for targeting endothelial P2RX7 for neurovascular protection during SE. PMID:25998681

  7. Tactile surface classification for limbed robots using a pressure sensitive robot skin.

    PubMed

    Shill, Jacob J; Collins, Emmanuel G; Coyle, Eric; Clark, Jonathan

    2015-01-01

    This paper describes an approach to terrain identification based on pressure images generated through direct surface contact using a robot skin constructed around a high-resolution pressure sensing array. Terrain signatures for classification are formulated from the magnitude frequency responses of the pressure images. The initial experimental results for statically obtained images show that the approach yields classification accuracies [Formula: see text]. The methodology is extended to accommodate the dynamic pressure images anticipated when a robot is walking or running. Experiments with a one-legged hopping robot yield similar identification accuracies [Formula: see text]. In addition, the accuracies are independent with respect to changing robot dynamics (i.e., when using different leg gaits). The paper further shows that the high-resolution capabilities of the sensor enables similarly textured surfaces to be distinguished. A correcting filter is developed to accommodate for failures or faults that inevitably occur within the sensing array with continued use. Experimental results show using the correcting filter can extend the effective operational lifespan of a high-resolution sensing array over 6x in the presence of sensor damage. The results presented suggest this methodology can be extended to autonomous field robots, providing a robot with crucial information about the environment that can be used to aid stable and efficient mobility over rough and varying terrains. PMID:25642694

  8. Sensitive cesium measurement in liquid sample using low-pressure laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Zhen Zhen; Yan, Jun Jie; Liu, Ji Ping; Deguchi, Yoshihiro; Katsumori, Shunpei; Ikutomo, Akihiro

    2015-12-01

    The environmental pollution by trace heavy metals is a severe problem for the environment and human health. In this paper, the liquid jet of CsNO3 solution employed was introduced to the measurement chamber and detected using laser-induced breakdown spectroscopy (LIBS) directly at low pressure to determine the detection features of trace Cs element in liquid. The distinct and round plasma can be acquired when reducing the pressure. The interaction between the plasma core of the liquid jet and the surrounding gas can be controlled to enhance Cs detection ability. Cs emission was mainly in the surrounding area in the plasma. The influences of laser focal point and plasma measurement area on the measured signals were studied under low-pressure condition. When employing the defocus mode and varying the measurement area within a certain range, Cs signal and the signal-to-background ratio were improved. Cs detection limit can reach to 22.8 ppb (3σ/ms) at pressure of 26 kPa in this paper. According to the discussion, the detection limit will be enhanced when improving the experimental conditions using this method, which shows the great application potential of liquid sample measurement.

  9. Effect of two consecutive spinal manipulations in a single session on myofascial pain pressure sensitivity: a randomized controlled trial

    PubMed Central

    Laframboise, Michelle A.; Vernon, Howard; Srbely, John

    2016-01-01

    Objective: To investigate the summative effect of two consecutive spinal manipulative therapy (SMT) interventions within the same session on the pain pressure sensitivity of neurosegmentally linked myofascial tissues. Methods: 26 participants were recruited and assessed for the presence of a clinically identifiable myofascial trigger point in the right infraspinatus muscle. Participants were randomly assigned to test or control group. Test group received two consecutive real cervical SMT interventions to C5–C6 segment while controls received one real SMT followed by one validated sham SMT intervention to C5–C6 segment. Participants received the two consecutive SMT interventions 30 minutes apart. Pain pressure threshold (PPT) readings were recorded at pre-SMT1 and 5, 10, 15, 20 and 25 minutes post-SMT1 and post-SMT2. PPT readings were normalized to pre-SMT1 values and averaged. Results: Repeated measures ANOVA demonstrated a significant main effect of SMT intervention [F(1,24)=8.60, p<0.05] but not group [F(1.24)=0.01] (p=0.91). Post-hoc comparisons demonstrated a statistically significant (p<0.05) increase in SMT2 versus SMT1 (18%) in the test group but not in controls (4%) (p=0.82). Conclusions: Two consecutive SMT interventions evoke significant decreases in mechanical pressure sensitivity (increased PPT) within neurosegmentally linked myofascial tissues. The antinociceptive effects of SMT may be summative and governed by a dose-response relationship in myofascial tissues. PMID:27385833

  10. Free-field Calibration of the Pressure Sensitivity of Microphones at Frequencies up to 80 kHz

    NASA Technical Reports Server (NTRS)

    Herring, G. C.; Zuckerwar, Allan J.; Elbing, Brian R.

    2006-01-01

    A free-field (FF) substitution method for calibrating the pressure sensitivity of microphones at frequencies up to 80 kHz is demonstrated with both grazing and normal incidence geometries. The substitution-based method, as opposed to a simultaneous method, avoids problems associated with the non-uniformity of the sound field and, as applied here, uses a 1/2 -inch air-condenser pressure microphone as a known reference. Best results were obtained with a centrifugal fan, which is used as a random, broadband sound source. A broadband source minimizes reflection-related interferences that often plague FF measurements. Calibrations were performed on 1/4-inch FF air-condenser, electret, and micro-electromechanical systems (MEMS) microphones in an anechoic chamber. The accuracy of this FF method is estimated by comparing the pressure sensitivity of an air-condenser microphone, as derived from the FF measurement, with that of an electrostatic actuator calibration and is typically 0.3 dB (95% confidence), over the range 2-80 kHz.

  11. Calibration of the pressure sensitivity of microphones by a free-field method at frequencies up to 80 khz.

    PubMed

    Zuckerwar, Allan J; Herring, G C; Elbing, Brian R

    2006-01-01

    A free-field (FF) substitution method for calibrating the pressure sensitivity of microphones at frequencies up to 80 kHz is demonstrated with both grazing and normal-incidence geometries. The substitution-based method, as opposed to a simultaneous method, avoids problems associated with the nonuniformity of the sound field and, as applied here, uses a 1/4-in. air-condenser pressure microphone as a known reference. Best results were obtained with a centrifugal fan, which is used as a random, broadband sound source. A broadband source minimizes reflection-related interferences that can plague FF measurements. Calibrations were performed on 1/4-in. FF air-condenser, electret, and microelectromechanical systems (MEMS) microphones in an anechoic chamber. The uncertainty of this FF method is estimated by comparing the pressure sensitivity of an air-condenser FF microphone, as derived from the FF measurement, with that of an electrostatic actuator calibration. The root-mean-square difference is found to be +/- 0.3 dB over the range 1-80 kHz, and the combined standard uncertainty of the FF method, including other significant contributions, is +/- 0.41 dB. PMID:16454287

  12. 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.

  13. 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).

  14. 75 FR 17124 - Pressure Sensitive Plastic Tape from Italy: Notice of Continuation of Antidumping Duty Finding

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-05

    ... Act of 1930, as amended (the Act). See Initiation of Five-Year Sunset Review, 74 FR 20286 (May 1, 2009... Review, 74 FR 40811 (August 13, 2009) (Final Results).\\1\\ \\1\\ On October 26, 2009, the Department placed... Sensitive Plastic Tape from Italy; Determination, 75 FR 14628 (March 26, 2010). Scope of the Finding...

  15. Sensitive determination of herbicides in food samples by nonaqueous CE using pressurized liquid extraction.

    PubMed

    Carabias-Martínez, Rita; Rodríguez-Gonzalo, Encarnacion; Miranda-Cruz, Edith; Domínguez-Alvarez, Javier; Hernández-Méndez, Jesus

    2007-10-01

    We have developed a method involving extraction with mixtures of solvents under pressure (pressurized liquid extraction (PLE)) for the determination of triazine herbicides in a series of samples from the food industry. The organic extracts obtained were subjected to a clean-up step with SPE, using Oasis MCX sorbents, after which they were analyzed by NACE. Potato was chosen as a representative matrix of horticultural products since it has a high water content. Spiked potato samples were used to optimize extraction conditions. In order to compare the results obtained with NACE, different studies were also conducted using HPLC. The detection limits in NACE were similar to those found with HPLC and were of the order of 10-15 microg/kg, depending on the analyte. Satisfactory results were obtained on applying the method proposed for the potato matrix (PLE with separation by electrophoresis) to other food matrices such as other tubercles, fruits, vegetables and cereals. PMID:17893944

  16. Pressure-Sensitive Paint and Video Model Deformation Systems at the NASA Langley Unitary Plan Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Erickson, G. E.; Burner, A. W.; DeLoach, R.

    1999-01-01

    Pressure-sensitive paint (PSP) and video model deformation (VMD) systems have been installed in the Unitary Plan Wind Tunnel at the NASA Langley Research Center to support the supersonic wind tunnel testing requirements of the High Speed Research (HSR) program. The PSP and VMD systems have been operational since early 1996 and provide the capabilities of measuring global surface static pressures and wing local twist angles and deflections (bending). These techniques have been successfully applied to several HSR wind tunnel models for wide ranges of the Mach number, Reynolds number, and angle of attack. A review of the UPWT PSP and VMD systems is provided, and representative results obtained on selected HSR models are shown. A promising technique to streamline the wind tunnel testing process, Modern Experimental Design, is also discussed in conjunction with recently-completed wing deformation measurements at UPWT.

  17. Pressure-Sensitive Paint Measurements on the NASA Common Research Model in the NASA 11-ft Transonic Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Bell, James H.

    2011-01-01

    The luminescence lifetime technique was used to make pressure-sensitive paint (PSP) measurements on a 2.7% Common Research Model in the NASA Ames 11ft Transonic Wind Tunnel. PSP data were obtained on the upper and lower surfaces of the wing and horizontal tail, as well as one side of the fuselage. Data were taken for several model attitudes of interest at Mach numbers between 0.70 and 0.87. Image data were mapped onto a three-dimensional surface grid suitable both for comparison with CFD and for integration of pressures to determine loads. Luminescence lifetime measurements were made using strobed LED (light-emitting diode) lamps to illuminate the PSP and fast-framing interline transfer cameras to acquire the PSP emission.

  18. Oxygen at 2 atmospheres absolute pressure does not increase the radiation sensitivity of normal brain in rats

    SciTech Connect

    Routh, A.; Kapp, J.P.; Smith, E.E.; Bebin, J.; Barnes, T.; Hickman, B.T.

    1984-07-01

    Cranial radiation was administered to CD Fisher rats at 1.0, 1.5 and 2.0 atmospheres oxygen pressure. Life span following radiation was recorded. Surviving animals were killed at 28 weeks and the brains were examined independently by two neuropathologists. Survival time was significantly less in animals receiving higher doses of radiation but showed no relationship to the oxygen pressure in the environment of the animal at the time radiation was administered. Microscopic examination of the brain did not reveal any differences in animals radiated in a normobaric or hyperbaric oxygen environment. It is concluded that hyperbaric oxygen does not sensitize the normal brain to the effects of ionizing radiation.

  19. Pressure sensitivity of olivine slip systems and seismic anisotropy of Earth's upper mantle.

    PubMed

    Mainprice, David; Tommasi, Andréa; Couvy, Hélène; Cordier, Patrick; Frost, Daniel J

    2005-02-17

    The mineral olivine dominates the composition of the Earth's upper mantle and hence controls its mechanical behaviour and seismic anisotropy. Experiments at high temperature and moderate pressure, and extensive data on naturally deformed mantle rocks, have led to the conclusion that olivine at upper-mantle conditions deforms essentially by dislocation creep with dominant [100] slip. The resulting crystal preferred orientation has been used extensively to explain the strong seismic anisotropy observed down to 250 km depth. The rapid decrease of anisotropy below this depth has been interpreted as marking the transition from dislocation to diffusion creep in the upper mantle. But new high-pressure experiments suggest that dislocation creep also dominates in the lower part of the upper mantle, but with a different slip direction. Here we show that this high-pressure dislocation creep produces crystal preferred orientations resulting in extremely low seismic anisotropy, consistent with seismological observations below 250 km depth. These results raise new questions about the mechanical state of the lower part of the upper mantle and its coupling with layers both above and below. PMID:15716950

  20. Results From a Pressure Sensitive Paint Test Conducted at the National Transonic Facility on Test 197: The Common Research Model

    NASA Technical Reports Server (NTRS)

    Watkins, A. Neal; Lipford, William E.; Leighty, Bradley D.; Goodman, Kyle Z.; Goad, William K.; Goad, Linda R.

    2011-01-01

    This report will serve to present results of a test of the pressure sensitive paint (PSP) technique on the Common Research Model (CRM). This test was conducted at the National Transonic Facility (NTF) at NASA Langley Research Center. PSP data was collected on several surfaces with the tunnel operating in both cryogenic mode and standard air mode. This report will also outline lessons learned from the test as well as possible approaches to challenges faced in the test that can be applied to later entries.

  1. Study on demodulated signal distribution and acoustic pressure phase sensitivity of a self-interfered distributed acoustic sensing system

    NASA Astrophysics Data System (ADS)

    Shang, Ying; Yang, Yuan-Hong; Wang, Chen; Liu, Xiao-Hui; Wang, Chang; Peng, Gang-Ding

    2016-06-01

    We propose a demodulated signal distribution theory for a self-interfered distributed acoustic sensing system. The distribution region of Rayleigh backscattering including the acoustic sensing signal in the sensing fiber is investigated theoretically under different combinations of both the path difference and pulse width Additionally we determine the optimal solution between the path difference and pulse width to obtain the maximum phase change per unit length. We experimentally test this theory and realize a good acoustic pressure phase sensitivity of  ‑150 dB re rad/(μPa·m) of fiber in the frequency range from 200 Hz to 1 kHz.

  2. Pore pressure sensitivities to dynamic strains: Observations in active tectonic regions

    NASA Astrophysics Data System (ADS)

    Barbour, Andrew J.

    2015-08-01

    Triggered seismicity arising from dynamic stresses is often explained by the Mohr-Coulomb failure criterion, where elevated pore pressures reduce the effective strength of faults in fluid-saturated rock. The seismic response of a fluid-rock system naturally depends on its hydromechanical properties, but accurately assessing how pore fluid pressure responds to applied stress over large scales in situ remains a challenging task; hence, spatial variations in response are not well understood, especially around active faults. Here I analyze previously unutilized records of dynamic strain and pore pressure from regional and teleseismic earthquakes at Plate Boundary Observatory (PBO) stations from 2006 to 2012 to investigate variations in response along the Pacific/North American tectonic plate boundary. I find robust scaling response coefficients between excess pore pressure and dynamic strain at each station that are spatially correlated: around the San Andreas and San Jacinto fault systems, the response is lowest in regions of the crust undergoing the highest rates of secular shear strain. PBO stations in the Parkfield instrument cluster are at comparable distances to the San Andreas Fault (SAF), and spatial variations there follow patterns in dextral creep rates along the fault, with the highest response in the actively creeping section, which is consistent with a narrowing zone of strain accumulation seen in geodetic velocity profiles. At stations in the San Juan Bautista (SJB) and Anza instrument clusters, the response depends nonlinearly on the inverse fault-perpendicular distance, with the response decreasing toward the fault; the SJB cluster is at the northern transition from creeping-to-locked behavior along the SAF, where creep rates are at moderate to low levels, and the Anza cluster is around the San Jacinto Fault, where to date there have been no statistically significant creep rates observed at the surface. These results suggest that the strength of the

  3. Liposome adhesion generates traction stress

    NASA Astrophysics Data System (ADS)

    Murrell, Michael P.; Voituriez, Raphaël; Joanny, Jean-François; Nassoy, Pierre; Sykes, Cécile; Gardel, Margaret L.

    2014-02-01

    Mechanical forces generated by cells modulate global shape changes required for essential life processes, such as polarization, division and spreading. Although the contribution of the cytoskeleton to cellular force generation is widely recognized, the role of the membrane is considered to be restricted to passively transmitting forces. Therefore, the mechanisms by which the membrane can directly contribute to cell tension are overlooked and poorly understood. To address this, we directly measure the stresses generated during liposome adhesion. We find that liposome spreading generates large traction stresses on compliant substrates. These stresses can be understood as the equilibration of internal, hydrostatic pressures generated by the enhanced membrane tension built up during adhesion. These results underscore the role of membranes in the generation of mechanical stresses on cellular length scales and that the modulation of hydrostatic pressure due to membrane tension and adhesion can be channelled to perform mechanical work on the environment.

  4. An electrically and mechanically self-healing composite with pressure- and flexion-sensitive properties for electronic skin applications

    NASA Astrophysics Data System (ADS)

    Tee, Benjamin C.-K.; Wang, Chao; Allen, Ranulfo; Bao, Zhenan

    2012-12-01

    Pressure sensitivity and mechanical self-healing are two vital functions of the human skin. A flexible and electrically conducting material that can sense mechanical forces and yet be able to self-heal repeatably can be of use in emerging fields such as soft robotics and biomimetic prostheses, but combining all these properties together remains a challenging task. Here, we describe a composite material composed of a supramolecular organic polymer with embedded nickel nanostructured microparticles, which shows mechanical and electrical self-healing properties at ambient conditions. We also show that our material is pressure- and flexion-sensitive, and therefore suitable for electronic skin applications. The electrical conductivity can be tuned by varying the amount of nickel particles and can reach values as high as 40 S cm-1. On rupture, the initial conductivity is repeatably restored with ~90% efficiency after 15 s healing time, and the mechanical properties are completely restored after ~10 min. The composite resistance varies inversely with applied flexion and tactile forces. These results demonstrate that natural skin's repeatable self-healing capability can be mimicked in conductive and piezoresistive materials, thus potentially expanding the scope of applications of current electronic skin systems.

  5. Comments on "Sensitive analysis of carbon, chromium and silicon in steel using picosecond laser induced low pressure helium plasma"

    NASA Astrophysics Data System (ADS)

    Zaytsev, Sergey M.; Popov, Andrey M.; Zorov, Nikita B.; Labutin, Timur A.

    2016-04-01

    In the paper "Sensitive analysis of carbon, chromium and silicon in steel using picosecond laser induced low pressure helium plasma" by Syahrun Nur Abdulmadjid, Nasrullah Idris, Marincan Pardede, Eric Jobiliong, Rinda Hedwig, Zener Sukra Lie, Hery Suyanto, May On Tjia, Koo Hendrik Kurniawan and Kiichiro Kagawa [Spectrochim. Acta Part B 114 (2015) 1-6], the authors presented experimental study to demonstrate the sensitive detection of C, Cr and Si in low-alloy steels under low pressure He atmosphere. Although the use of only UV-VIS spectral range for determination of these elements seems to be a beneficial, the point that needs to be commented is the result of carbon determination with the use of C I 247.856 nm line. Thermodynamic modeling based on the NIST and R. Kurucz data for the different excitation conditions in plasma demonstrates that it is hardly possible to distinguish any carbon signal due to significantly intensive iron line Fe II 247.857 nm. Authors are kindly requested to re-consider this part of their study.

  6. Chronic Angiotensin-(1-7) Improves Insulin Sensitivity in High-Fat Fed Mice Independent of Blood Pressure.

    PubMed

    Williams, Ian M; Otero, Yolanda F; Bracy, Deanna P; Wasserman, David H; Biaggioni, Italo; Arnold, Amy C

    2016-05-01

    Angiotensin-(1-7) improves glycemic control in animal models of cardiometabolic syndrome. The tissue-specific sites of action and blood pressure dependence of these metabolic effects, however, remain unclear. We hypothesized that Ang-(1-7) improves insulin sensitivity by enhancing peripheral glucose delivery. Adult male C57BL/6J mice were placed on standard chow or 60% high-fat diet for 11 weeks. Ang-(1-7) (400 ng/kg per minute) or saline was infused subcutaneously during the last 3 weeks of diet, and hyperinsulinemic-euglycemic clamps were performed at the end of treatment. High-fat fed mice exhibited modest hypertension (systolic blood pressure: 137 ± 3 high fat versus 123 ± 5 mm Hg chow;P=0.001), which was not altered by Ang-(1-7) (141 ± 4 mm Hg;P=0.574). Ang-(1-7) did not alter body weight or fasting glucose and insulin in chow or high-fat fed mice. Ang-(1-7) increased the steady-state glucose infusion rate needed to maintain euglycemia in high-fat fed mice (31 ± 5 Ang-(1-7) versus 16 ± 1 mg/kg per minute vehicle;P=0.017) reflecting increased whole-body insulin sensitivity, with no effect in chow-fed mice. The improved insulin sensitivity in high-fat fed mice was because of an enhanced rate of glucose disappearance (34 ± 5 Ang-(1-7) versus 20 ± 2 mg/kg per minute vehicle;P=0.049). Ang-(1-7) enhanced glucose uptake specifically into skeletal muscle by increasing translocation of glucose transporter 4 to the sarcolemma. Our data suggest that Ang-(1-7) has direct insulin-sensitizing effects on skeletal muscle, independent of changes in blood pressure. These findings provide new insight into mechanisms by which Ang-(1-7) improves insulin action, and provide further support for targeting this peptide in cardiometabolic disease. PMID:26975707

  7. GAIT ANALYSIS IN GIANT ANTEATER (MYRMECOPHAGA TRIDACTYLA) WITH THE USE OF A PRESSURE-SENSITIVE WALKWAY.

    PubMed

    de Faria, Luís Guilherme; Rahal, Sheila Canevese; dos Reis Mesquita, Luciane; Agostinho, Felipe Stefan; Kano, Washington Takashi; Teixeira, Carlos Roberto; Monteiro, Frederico Ozanan Barros

    2015-06-01

    The aim of this study was to evaluate the kinetic and temporospatial parameters of clinically healthy juvenile giant anteaters (Myrmecophaga tridactyla) by using a pressure-sensing walkway. Three free-ranging clinically healthy giant anteaters (M. tridactyla), two males and one female, aged 5-7 mo, were used. There was no statistically significant difference between the right and left sides for the kinetic and temporospatial parameters for both forelimbs and hind limbs. Although the gait velocity was similar for all giant anteaters, the stride frequency was higher in the smaller anteaters. The difference in stride frequency is associated with body size, which also influenced other temporospatial parameters. The percentage of body distribution was higher on the forelimbs than the hind limbs. The contact surface and trajectory of the force of the forepaws differed from the hind paws. In conclusion, the anteaters have gait peculiarities associated with the anatomical differences between forelimbs and hind limbs. PMID:26056881

  8. Sensitivity analysis of the pressure-based direct integrity test for membranes used in drinking water treatment.

    PubMed

    Minnery, John G; Jacangelo, Joseph G; Boden, Leslie I; Vorhees, Donna J; Heiger-Bernays, Wendy

    2009-12-15

    We conducted a sensitivity analysis of the commonly employed pressure-based direct integrity test (DIT), the most sensitive test for defects in low-pressure hollow fiber (LPHF) microfiltration and ultrafiltration systems used in drinking water treatment. Incorporating uncertainty to assess the practice of DIT, we find the resolution in some tests may be insufficient to verify the presence of a barrier to oocysts of Cryptosporidium. Applying distributions and boundaries derived from literature and practice, we solved for the defect size resolution (DSR) using Monte Carlo and Probability Bounds Analysis for five commercial membrane designs. Surface tension was modeled using annual temperature profiles from three rivers. Contact angle measurement error and variability were derived from literature, respectively, as a standard deviation of 5.7 degrees and +/- 9.6 degrees median change due to natural organic matter (NOM) fouling. These measures of contact angle uncertainty and variability were combined in a normal distribution with the discrete values currently applied. Additionally we considered model uncertainty, applying the maximum bubble pressure method, an established method of surface tension measurement in liquids in which the maximum air pressure in a submerged capillary is developed after the contact angle becomes zero prior to bubble formation. Where the DSR exceeds 3 microm the test design is not compliant with applicable drinking water regulations. Implications include uncertain and variable log-removal values (LRV) as determined by DIT due to the possible emergence of defects large enough to allow oocysts to pass without detection by the DIT. Specifically, we found the DSR may exceed 3 microm and may be as large as 8 microm. With the variable contact angle model, all lower bound possibilities are compliant, whereas the upper bound is over 80% noncompliant for three of five commercial designs. Using the Maximum Bubble Pressure Method, the lower bounds in

  9. Critical Chemical-Mechanical Couplings that Define Permeability Modifications in Pressure-Sensitive Rock Fractures

    SciTech Connect

    Derek Elsworth; Abraham Grader; Susan Brantley

    2007-04-25

    This work examined and quantified processes controlling changes in the transport characteristics of natural fractures, subjected to coupled thermal-mechanical-chemical (TMC) effects. Specifically, it examined the effects of mineral dissolution and precipitation mediated by mechanical effects, using laboratory through-flow experiments concurrently imaged by X-ray CT. These were conducted on natural and artificial fractures in cores using water as the permeant. Fluid and mineral mass balances are recorded and are correlated with in-sample saturation, porosity and fracture aperture maps, acquired in real-time by X-ray CT-imaging at a maximum spatial resolution of 15-50 microns per pixel. Post-test, the samples were resin-impregnated, thin-sectioned, and examined by microscopy to define the characteristics of dissolution and precipitation. The test-concurrent X-ray imaging, mass balances, and measurements of permeability, together with the post-test microscopy, were used to define dissolution/precipitation processes, and to constrain process-based models. These models define and quantify key processes of pressure solution, free-face dissolution, and shear-dilation, and the influence of temperature, stress level, and chemistry on the rate of dissolution, its distribution in space and time, and its influence on the mechanical and transport properties of the fracture.

  10. Enhanced blood pressure sensitivity to DOCA-salt treatment in endothelin ETB receptor-deficient rats

    PubMed Central

    Matsumura, Yasuo; Kuro, Toshihiko; Konishi, Fumiko; Takaoka, Masanori; Gariepy, Cheryl E; Yanagisawa, Masashi

    2000-01-01

    The role of endothelin ETB receptor-mediated action in the development and maintenance of deoxycorticosterone acetate (DOCA)-salt-induced hypertension was evaluated using the spotting-lethal (sl) rat which carries a naturally occurring deletion in the ETB receptor gene. Homozygous (sl/sl) rats treated with DOCA-salt for 1 week exhibited an earlier onset of hypertension than heterozygous (sl/+) and wild-type (+/+) rats (systolic blood pressure, SBP; 156.7±3.4 versus 128.8±5.3 and 132.9±3.7 mmHg, respectively). Four weeks after the start of DOCA-salt treatment, homozygous rats developed marked hypertension, with a SBP of 206.0±4.5 mmHg, compared with 184.8±10.7 mmHg in heterozygous and 164.3±4.8 mmHg in wild-type rats. Cardiovascular hypertrophy and renal dysfunction observed after 4-weeks treatment with DOCA-salt were more severe in homozygous rats, compared to wild-type and heterozygous animals. These evidences support strongly the view that ETB receptor-mediated actions are a protective factor in the pathogenesis of DOCA-salt-induced hypertension. PMID:10725252

  11. Inhibition on Apoptosis Induced by Elevated Hydrostatic Pressure in Retinal Ganglion Cell-5 via Laminin Upregulating β1-integrin/Focal Adhesion Kinase/Protein Kinase B Signaling Pathway

    PubMed Central

    Li, Yi; Chen, Yan-Ming; Sun, Ming-Ming; Guo, Xiao-Dan; Wang, Ya-Chen; Zhang, Zhong-Zhi

    2016-01-01

    Background: Glaucoma is a progressive optic neuropathy characterized by degeneration of neurons due to loss of retinal ganglion cells (RGCs). High intraocular pressure (HIOP), the main risk factor, causes the optic nerve damage. However, the precise mechanism of HIOP-induced RGC death is not yet completely understood. This study was conducted to determine apoptosis of RGC-5 cells induced by elevated hydrostatic pressures, explore whether laminin is associated with apoptosis under pressure, whether laminin can protect RGCs from apoptosis and affirm the mechanism that regulates the process of RGCs survival. Methods: RGC-5 cells were exposed to 0, 20, 40, and 60 mmHg in a pressurized incubator for 6, 12, and 24 h, respectively. The effect of elevated hydrostatic pressure on RGC-5 cells was measured by Annexin V-fluorescein isothiocyanate/propidium iodide staining, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and Western blotting of cleaved caspase-3 protein. Location and expression of laminin were detected by immunofluorescence. The expression of β1-integrin, phosphorylation of focal adhesion kinase (FAK) and protein kinase B (PKB, or AKT) were investigated with real-time polymerase chain reaction and Western blotting analysis. Results: Elevated hydrostatic pressure induced apoptosis in cultured RGC-5 cells. Pressure with 40 mmHg for 24 h induced a maximum apoptosis. Laminin was declined in RGC-5 cells after exposing to 40 mmHg for 24 h. After pretreating with laminin, RGC-5 cells survived from elevated pressure. Furthermore, β1-integrin and phosphorylation of FAK and AKT were increased compared to 40 mmHg group. Conclusions: The data show apoptosis tendency of RGC-5 cells with elevated hydrostatic pressure. Laminin can protect RGC-5 cells against high pressure via β1-integrin/FAK/AKT signaling pathway. These results suggest that the decreased laminin of RGC-5 cells might be responsible for apoptosis induced by elevated hydrostatic pressure

  12. Glucocorticoids Induce Nondipping Blood Pressure by Activating the Thiazide-Sensitive Cotransporter.

    PubMed

    Ivy, Jessica R; Oosthuyzen, Wilna; Peltz, Theresa S; Howarth, Amelia R; Hunter, Robert W; Dhaun, Neeraj; Al-Dujaili, Emad A S; Webb, David J; Dear, James W; Flatman, Peter W; Bailey, Matthew A

    2016-05-01

    Blood pressure (BP) normally dips during sleep, and nondipping increases cardiovascular risk. Hydrochlorothiazide restores the dipping BP profile in nondipping patients, suggesting that the NaCl cotransporter, NCC, is an important determinant of daily BP variation. NCC activity in cells is regulated by the circadian transcription factor per1. In vivo, circadian genes are entrained via the hypothalamic-pituitary-adrenal axis. Here, we test whether abnormalities in the day:night variation of circulating glucocorticoid influence NCC activity and BP control. C57BL6/J mice were culled at the peak (1:00 AM) and trough (1:00 PM) of BP. We found no day:night variation in NCC mRNA or protein but NCC phosphorylation on threonine(53)(pNCC), required for NCC activation, was higher when mice were awake, as was excretion of NCC in urinary exosomes. Peak NCC activity correlated with peak expression of per2 and bmal1 (clock genes) and sgk1 and tsc22d3 (glucocorticoid-responsive kinases). Adrenalectomy reduced NCC abundance and blunted the daily variation in pNCC levels without affecting variation in clock gene transcription. Chronic corticosterone infusion increased bmal1, per1, sgk1, and tsc22d3 expression during the inactive phase. Inactive phase pNCC was also elevated by corticosterone, and a nondipping BP profile was induced. Hydrochlorothiazide restored rhythmicity of BP in corticosterone-treated mice without affecting BP in controls. Glucocorticoids influence the day:night variation in NCC activity via kinases that control phosphorylation. Abnormal glucocorticoid rhythms impair NCC and induce nondipping. Night-time dosing of thiazides may be particularly beneficial in patients with modest glucocorticoid excess. PMID:26953322

  13. Glucocorticoids Induce Nondipping Blood Pressure by Activating the Thiazide-Sensitive Cotransporter

    PubMed Central

    Ivy, Jessica R.; Oosthuyzen, Wilna; Peltz, Theresa S.; Howarth, Amelia R.; Hunter, Robert W.; Dhaun, Neeraj; Al-Dujaili, Emad A.S.; Webb, David J.; Dear, James W.; Flatman, Peter W.

    2016-01-01

    Blood pressure (BP) normally dips during sleep, and nondipping increases cardiovascular risk. Hydrochlorothiazide restores the dipping BP profile in nondipping patients, suggesting that the NaCl cotransporter, NCC, is an important determinant of daily BP variation. NCC activity in cells is regulated by the circadian transcription factor per1. In vivo, circadian genes are entrained via the hypothalamic–pituitary–adrenal axis. Here, we test whether abnormalities in the day:night variation of circulating glucocorticoid influence NCC activity and BP control. C57BL6/J mice were culled at the peak (1:00 AM) and trough (1:00 PM) of BP. We found no day:night variation in NCC mRNA or protein but NCC phosphorylation on threonine53 (pNCC), required for NCC activation, was higher when mice were awake, as was excretion of NCC in urinary exosomes. Peak NCC activity correlated with peak expression of per2 and bmal1 (clock genes) and sgk1 and tsc22d3 (glucocorticoid-responsive kinases). Adrenalectomy reduced NCC abundance and blunted the daily variation in pNCC levels without affecting variation in clock gene transcription. Chronic corticosterone infusion increased bmal1, per1, sgk1, and tsc22d3 expression during the inactive phase. Inactive phase pNCC was also elevated by corticosterone, and a nondipping BP profile was induced. Hydrochlorothiazide restored rhythmicity of BP in corticosterone-treated mice without affecting BP in controls. Glucocorticoids influence the day:night variation in NCC activity via kinases that control phosphorylation. Abnormal glucocorticoid rhythms impair NCC and induce nondipping. Night-time dosing of thiazides may be particularly beneficial in patients with modest glucocorticoid excess. PMID:26953322

  14. Tuning Light Emission of a Pressure-Sensitive Silicon/ZnO Nanowires Heterostructure Matrix through Piezo-phototronic Effects.

    PubMed

    Chen, Mengxiao; Pan, Caofeng; Zhang, Taiping; Li, Xiaoyi; Liang, Renrong; Wang, Zhong Lin

    2016-06-28

    Based on white light emission at silicon (Si)/ZnO hetrerojunction, a pressure-sensitive Si/ZnO nanowires heterostructure matrix light emitting diode (LED) array is developed. The light emission intensity of a single heterostructure LED is tuned by external strain: when the applied stress keeps increasing, the emission intensity first increases and then decreases with a maximum value at a compressive strain of 0.15-0.2%. This result is attributed to the piezo-phototronic effect, which can efficiently modulate the LED emission intensity by utilizing the strain-induced piezo-polarization charges. It could tune the energy band diagrams at the junction area and regulate the optoelectronic processes such as charge carriers generation, separation, recombination, and transport. This study achieves tuning silicon based devices through piezo-phototronic effect. PMID:27276167

  15. Single-Point but Not Tonic Cuff Pressure Pain Sensitivity Is Associated with Level of Physical Fitness – A Study of Non-Athletic Healthy Subjects

    PubMed Central

    Lemming, Dag; Börsbo, Björn; Sjörs, Anna; Lind, Eva-Britt; Arendt-Nielsen, Lars; Graven-Nielsen, Thomas; Gerdle, Björn

    2015-01-01

    Exercise is often used for pain rehabilitation but the link between physical activity level and pain sensitivity is still not fully understood. Pressure pain sensitivity to cuff algometry and conditioned pain modulation (CPM) were evaluated in highly active men (n=22), normally active men (n=26), highly active women (n=27) and normally active women (n=23) based on the Godin Leisure-Time Exercise Questionnaire. Cuff pressure pain sensitivity was assessed at the arm and lower leg. The subjects scored the pain intensity on an electronic Visual Analogue Scale (VAS) during ten minutes with 25 kPa constant cuff pressure and two minutes with zero pressure. The maximal VAS score and area under the VAS-curve were extracted. Pressure pain thresholds (PPT) were recorded by manual pressure algometry on the ipsilateral tibialis anterior muscle before, during and after the tonic arm stimulation. Tonic cuff stimulation of the arm and leg resulted in higher VAS peak scores in women compared with men (p<0.04). In all groups the PPTs were reduced during and after the cuff stimulation compared with baseline (p=0.001). PPT were higher in men compared with women (p=0.03) and higher in highly physical active compared with normal active (p=0.048). Besides the well-known gender difference in pressure pain sensitivity this study demonstrates that a high physical fitness degree in non-athletic subjects is associated with increased pressure pain thresholds but does not affect cuff pressure pain sensitivity in healthy people. PMID:25933412

  16. The roles of sensitization and neuroplasticity in the long-term regulation of blood pressure and hypertension.

    PubMed

    Johnson, Alan Kim; Zhang, Zhongming; Clayton, Sarah C; Beltz, Terry G; Hurley, Seth W; Thunhorst, Robert L; Xue, Baojian

    2015-12-01

    After decades of investigation, the causes of essential hypertension remain obscure. The contribution of the nervous system has been excluded by some on the basis that baroreceptor mechanisms maintain blood pressure only over the short term. However, this point of view ignores one of the most powerful contributions of the brain in maintaining biological fitness-specifically, the ability to promote adaptation of behavioral and physiological responses to cope with new challenges and maintain this new capacity through processes involving neuroplasticity. We present a body of recent findings demonstrating that prior, short-term challenges can induce persistent changes in the central nervous system to result in an enhanced blood pressure response to hypertension-eliciting stimuli. This sensitized hypertensinogenic state is maintained in the absence of the inducing stimuli, and it is accompanied by sustained upregulation of components of the brain renin-angiotensin-aldosterone system and other molecular changes recognized to be associated with central nervous system neuroplasticity. Although the heritability of hypertension is high, it is becoming increasingly clear that factors beyond just genes contribute to the etiology of this disease. Life experiences and attendant changes in cellular and molecular components in the neural network controlling sympathetic tone can enhance the hypertensive response to recurrent, sustained, or new stressors. Although the epigenetic mechanisms that allow the brain to be reprogrammed in the face of challenges to cardiovascular homeostasis can be adaptive, this capacity can also be maladaptive under conditions present in different evolutionary eras or ontogenetic periods. PMID:26290101

  17. High-sensitivity troponin T and cardiovascular events in systolic blood pressure categories: atherosclerosis risk in communities study.

    PubMed

    Pokharel, Yashashwi; Sun, Wensheng; de Lemos, James A; Taffet, George E; Virani, Salim S; Ndumele, Chiadi E; Mosley, Thomas H; Hoogeveen, Ron C; Coresh, Josef; Wright, Jacqueline D; Heiss, Gerardo; Boerwinkle, Eric A; Bozkurt, Biykem; Solomon, Scott D; Ballantyne, Christie M; Nambi, Vijay

    2015-01-01

    Based on observational studies, there is a linear increase in cardiovascular risk with higher systolic blood pressure (SBP), yet clinical trials have not shown benefit across all SBP categories. We assessed whether troponin T measured using high-sensitivity assay was associated with cardiovascular disease within SBP categories in 11 191 Atherosclerosis Risk in Communities study participants. Rested sitting SBP by 10-mm Hg increments and troponin categories were identified. Incident heart failure hospitalization, coronary heart disease, and stroke were ascertained for a median of 12 years after excluding individuals with corresponding disease. Approximately 53% of each type of cardiovascular event occurred in individuals with SBP<140 mm Hg and troponin T ≥3 ng/L. Higher troponin T was associated with increasing cardiovascular events across most SBP categories. The association was strongest for heart failure and least strong for stroke. There was no similar association of SBP with cardiovascular events across troponin T categories. Individuals with troponin T ≥3 ng/L and SBP <140 mm Hg had higher cardiovascular risk compared with those with troponin T <3 ng/L and SBP 140 to 159 mm Hg. Higher troponin T levels within narrow SBP categories portend increased cardiovascular risk, particularly for heart failure. Individuals with lower SBP but measurable troponin T had greater cardiovascular risk compared with those with suboptimal SBP but undetectable troponin T. Future trials of systolic hypertension may benefit by using high-sensitivity troponin T to target high-risk patients. PMID:25350984

  18. Enhancing the pressure sensitivity of a Fabry-Perot interferometer using a simplified hollow-core photonic crystal fiber with a microchannel

    NASA Astrophysics Data System (ADS)

    Yu, Yongqin; Chen, Xue; Huang, Quandong; Du, Chenlin; Ruan, Shuangchen; Wei, Huifeng

    2015-09-01

    We demonstrate a novel and compact fiber-probe pressure sensor based on a micro-Fabry-Perot interferometer (FPI). The device is fabricated by splicing both ends of a short-section simplified hollow-core photonic crystal fiber (SHC-PCF) with single-mode fibers. Then, a microchannel is drilled by a femtosecond laser micromachining in the SHC-PCF to allow air to diffuse in. The pressure sensing mechanism is based on the dependence of the air refractive index on pressure. We use both theory and experiment to investigate the sensing characteristics. A micro-FPI with a length of 272 μm demonstrates a pressure sensitivity of 4.071 nm/MPa at 1580 nm and a low-temperature sensitivity of 1.1 pm/°C at atmospheric pressure. We further study the temperature cross sensitivity of the sensor under different pressures. The sensor also shows strong stability and good reversibility, and may be potentially used in pressure sensing applications.

  19. Multi-directional ultra-high sensitive pressure sensor based on the integration of optimized double 60° bend waveguides and modified center-defect photonic crystal microcavity

    NASA Astrophysics Data System (ADS)

    Zhou, Jian; Yang, Daquan; Tian, Huiping; Huang, Lijun; Zhang, Pan; Ji, Yuefeng

    2015-06-01

    In the previous work [1], we have proposed a method to realize multi-directional pressure sensor. This follow-up work provides an optimized structure design based on the integration of double 60° bend waveguides and modified center-defect photonic crystal microcavity to further improve sensitivity. By applying two-dimensional finite difference time domain technologies (2D-FDTD) and finite-element methods (FEM), we systematically investigate the variations of optical properties under applied pressure. Linear relationships between the resonant wavelength shift and the applied pressure are obtained in three directions. The ultra-high sensitivities and the low minimum detectable pressure in longitudinal, transverse and upright directions are 39.7 nm/μN and 1.08 nN, 30.20 nm/μN and 1.43 nN, and 0.12 nm/nN and 0.36 nN respectively.

  20. Thermal Characterization of Adhesive

    NASA Technical Reports Server (NTRS)

    Spomer, Ken A.

    1999-01-01

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

  1. Neutron dosimetry in the containment of a pressurized water reactor using a neutron-sensitive beta/gamma dosimetry system

    SciTech Connect

    Kralick, S.C.; Watson, J.E. Jr.; Croslin, S.W.

    1986-06-01

    In this study the Panasonic UD-802 dosimeter was evaluated as a potential neutron dosimeter for use in the containment of a pressurized water reactor by comparing the results from the UD-802 with remmeter readings. The Panasonic UD-802 dosimeter is used routinely as a beta and gamma dosimeter but due to the natural Li and B in the thermoluminescent materials, it is also sensitive to neutrons. Since a dosimeter's response to neutrons is energy-dependent, proper calibration of the UD-802 in the environment for which it is to be used was an important consideration of the study. To calibrate the system, UD-802 dosimeters were mounted on polyethylene phantoms and irradiated to reference doses at selected locations in containment. The reference doses were determined based on remmeter dose-rate measurements and stay times. The thermoluminescent response of the dosimeters and the reference measurements were used to obtain a response ratio at each location. The average response ratio (unit of dosimeter response per millirem) was 3.7 and all response ratios were within +/-30% of this mean value. Specific characteristics of the UD-802 were also investigated, that is, the effects that dosimeter distance from the phantom and a person's movement through containment have on response. The dosimeter distance from the phantom was found to have a minimal effect on response, but the system was found to be dependent upon the angle of the phantom relative to the reactor core, necessitating a correction in the calibration factor. The overall conclusion of this study was that the Panasonic UD-802 dosimeter can be used for neutron dosimetry in containment of a pressurized water reactor.

  2. Culturally-sensitive weight loss program produces significant reduction in weight, blood pressure, and cholesterol in eight weeks.

    PubMed Central

    Ard, J. D.; Rosati, R.; Oddone, E. Z.

    2000-01-01

    Dietary and behavioral needs of special populations are rarely considered in traditional weight loss programs. This study assessed the impact of culturally-sensitive modifications to the Duke University Rice Diet weight loss program for African-American dieters. The study was a randomized modified cross-over study in which volunteers received either early or delayed weight loss intervention. Final outcomes were measured at 8 weeks. At the onset of the study, there were 56 African American participants, however, only 44 (79%) completed the study. The eight-week intervention was a modified 1000-calorie/day version of the Rice Diet. Modifications to the program included decreased cost, culturally-sensitive recipes, addressing attitudes about exercise, and including family members in weight loss efforts. Average weight loss for subjects completing the program was 14.8 pounds (SD = 6.8 pounds). BMI decreased from 37.8 kg/m2 to 35.3 kg/m2 (p < 0.01). Total cholesterol levels decreased from 199.2 mg/dL to 185.4 mg/dL (p < 0.01); systolic and diastolic blood pressure decreased by 4.3 mmHg (p < 0.01) and 2.4 mmHg (p < 0.05), respectively. The control group showed no significant change in any outcome measures. We found that diet programs can be successfully tailored to incorporate the needs of African-Americans. Most importantly, these dietary program changes can lead to significant improvement in clinical parameters. Additional studies are necessary to determine the permanence of these short-term changes. PMID:11152083

  3. 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.

  4. Understanding marine mussel adhesion.

    PubMed

    Silverman, Heather G; 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

  5. 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

  6. Impact of cold atmospheric pressure argon plasma on antibiotic sensitivity of methicillin-resistant Staphylococcus aureus strains in vitro

    PubMed Central

    Lührmann, Anne; Matthes, Rutger; Kramer, Axel

    2016-01-01

    Aim: The antimicrobial activity of cold atmospheric pressure plasma (CAP), also called tissue tolerable plasma (TTP), could be a promising option to eradicate methicillin-sensitive as well as methicillin-resistant Staphylococcus aureus strains, which often colonize chronic wounds. Currently, the influence of CAP on the susceptibility of S. aureus to antibiotics is scarcely known, but could be important for treatment of wounds. Therefore, the aim of this study was to investigate whether CAP has an impact on the susceptibility of different S. aureus strains to different antibiotics. Method: For assessment, the agar diffusion test with different antibiotic test disks (cefuroxime, gentamicin, oxacillin, vancomycin, ciprofloxacin, co-trimoxazole, clindamycin, erythromycin) was used. Test strains were spread on agar plates and CAP treated before the antibiotic disks were placed. After 24 hours cultivation, the inhibited growth zones were measured and differences statistically evaluated. Results: In most cases, CAP had a negligible influence on the susceptibility to antibiotics. For two strains, the susceptibility significantly decreased to β-lactam antibiotics. Conclusion: Because CAP can influence the antibiotic susceptibility of S. aureus, before conducting combined treatment with local plasma application on wounds and systemic antibiotics, their interaction must be analysed in vitro to exclude unwanted combination effects. PMID:27610332

  7. Functionalization of nanomaterials by non-thermal large area atmospheric pressure plasmas: application to flexible dye-sensitized solar cells.

    PubMed

    Jung, Heesoo; Park, Jaeyoung; Yoo, Eun Sang; Han, Gill-Sang; Jung, Hyun Suk; Ko, Min Jae; Park, Sanghoo; Choe, Wonho

    2013-09-01

    A key challenge to the industrial application of nanotechnology is the development of fabrication processes for functional devices based on nanomaterials which can be scaled up for mass production. In this report, we disclose the results of non-thermal radio-frequency (rf) atmospheric pressure plasma (APP) based deposition of TiO2 nanoparticles on a flexible substrate for the fabrication of dye-sensitized solar cells (DSSCs). Operating at 190 °C without a vacuum enclosure, the APP method can avoid thermal damage and vacuum compatibility restrictions and utilize roll-to-roll processing over a large area. The various analyses of the TiO2 films demonstrate that superior film properties can be obtained by the non-thermal APP method when compared with the thermal sintering process operating at 450 °C. The crystallinity of the anatase TiO2 nanoparticles is significantly improved without thermal agglomeration, while the surface defects such as Ti(3+) ions are eliminated, thus providing efficient charge collecting properties for solar cells. Finally, we successfully fabricated a flexible DSSC with an energy conversion efficiency of 4.2% using a transparent plastic substrate. This work demonstrates the potential of non-thermal APP technology in the area of device-level, nano-enabled material manufacturing. PMID:23831925

  8. Corneal Cell Adhesion to Contact Lens Hydrogel Materials Enhanced via Tear Film Protein Deposition

    PubMed Central

    Elkins, Claire M.; Qi, Qin M.; Fuller, Gerald G.

    2014-01-01

    Tear film protein deposition on contact lens hydrogels has been well characterized from the perspective of bacterial adhesion and viability. However, the effect of protein deposition on lens interactions with the corneal epithelium remains largely unexplored. The current study employs a live cell rheometer to quantify human corneal epithelial cell adhesion to soft contact lenses fouled with the tear film protein lysozyme. PureVision balafilcon A and AirOptix lotrafilcon B lenses were soaked for five days in either phosphate buffered saline (PBS), borate buffered saline (BBS), or Sensitive Eyes Plus Saline Solution (Sensitive Eyes), either pure or in the presence of lysozyme. Treated contact lenses were then contacted to a live monolayer of corneal epithelial cells for two hours, after which the contact lens was sheared laterally. The apparent cell monolayer relaxation modulus was then used to quantify the extent of cell adhesion to the contact lens surface. For both lens types, lysozyme increased corneal cell adhesion to the contact lens, with the apparent cell monolayer relaxation modulus increasing up to an order of magnitude in the presence of protein. The magnitude of this increase depended on the identity of the soaking solution: lenses soaked in borate-buffered solutions (BBS, Sensitive Eyes) exhibited a much greater increase in cell attachment upon protein addition than those soaked in PBS. Significantly, all measurements were conducted while subjecting the cells to moderate surface pressures and shear rates, similar to those experienced by corneal cells in vivo. PMID:25144576

  9. STOMATAL SENSITIVITY TO VAPOR PRESSURE DIFFERENCE OVER A SUBAMBIENT TO ELEVATED CO2 GRADIENT IN A C3/C4 GRASSLAND

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We examined the response of stomatal conductance (gs) to increasing leaf-to-air vapor pressure difference (D) in early season C3 (Bromus japonicus) and late season C4 (Bothriochloa ischaemum) grasses grown in the field across a range of CO2 (200-550 umol mol-1). Stomatal sensitivity to D was calcul...

  10. Large Area One-Step Facile Processing of Microstructured Elastomeric Dielectric Film for High Sensitivity and Durable Sensing over Wide Pressure Range.

    PubMed

    Chen, Sujie; Zhuo, Bengang; Guo, Xiaojun

    2016-08-10

    Once the requirement of sensitivity has been met, to enable a flexible pressure sensor technology to be widely adopted as an economic and convenient way for sensing diverse human body motions, critical factors need to be considered including low manufacturing cost, a large pressure detection range, and low power consumption. In this work, a facile approach is developed for one-step processing of a large area microstructured elastomer film with high density microfeatures of air voids, which can be seamlessly integrated into the process flow for fabricating flexible capacitive sensors. The fabricated sensors exhibit fast response and high sensitivity in the low pressure range to be able to detect very weak pressure down to 1 Pa and perform reliable wrist pulse monitoring. Compared to previous work, more advantageous features of this sensor are relatively high sensitivity being maintained in a wide pressure range up to 250 kPa and excellent durability under heavy load larger than 1 MPa, attributed to the formed dense air voids inside the film. A smart insole made with the sensor can accurately monitor the real-time walking or running behaviors and even a small weight change less than 1 kg under a heavy load of a 70 kg adult. For both application examples of wrist pulse monitoring and smart insole, the sensors are operated in a 3.3 V electronic system powered by a Li-ion battery, showing the potential for power-constrained wearable applications. PMID:27427977

  11. Genome-Wide Gene-Sodium Interaction Analyses on Blood Pressure: The Genetic Epidemiology Network of Salt-Sensitivity Study.

    PubMed

    Li, Changwei; He, Jiang; Chen, Jing; Zhao, Jinying; Gu, Dongfeng; Hixson, James E; Rao, Dabeeru C; Jaquish, Cashell E; Gu, Charles C; Chen, Jichun; Huang, Jianfeng; Chen, Shufeng; Kelly, Tanika N

    2016-08-01

    We performed genome-wide analyses to identify genomic loci that interact with sodium to influence blood pressure (BP) using single-marker-based (1 and 2 df joint tests) and gene-based tests among 1876 Chinese participants of the Genetic Epidemiology Network of Salt-Sensitivity (GenSalt) study. Among GenSalt participants, the average of 3 urine samples was used to estimate sodium excretion. Nine BP measurements were taken using a random zero sphygmomanometer. A total of 2.05 million single-nucleotide polymorphisms were imputed using Affymetrix 6.0 genotype data and the Chinese Han of Beijing and Japanese of Tokyo HapMap reference panel. Promising findings (P<1.00×10(-4)) from GenSalt were evaluated for replication among 775 Chinese participants of the Multi-Ethnic Study of Atherosclerosis (MESA). Single-nucleotide polymorphism and gene-based results were meta-analyzed across the GenSalt and MESA studies to determine genome-wide significance. The 1 df tests identified interactions for UST rs13211840 on diastolic BP (P=3.13×10(-9)). The 2 df tests additionally identified associations for CLGN rs2567241 (P=3.90×10(-12)) and LOC105369882 rs11104632 (P=4.51×10(-8)) with systolic BP. The CLGN variant rs2567241 was also associated with diastolic BP (P=3.11×10(-22)) and mean arterial pressure (P=2.86×10(-15)). Genome-wide gene-based analysis identified MKNK1 (P=6.70×10(-7)), C2orf80 (P<1.00×10(-12)), EPHA6 (P=2.88×10(-7)), SCOC-AS1 (P=4.35×10(-14)), SCOC (P=6.46×10(-11)), CLGN (P=3.68×10(-13)), MGAT4D (P=4.73×10(-11)), ARHGAP42 (P≤1.00×10(-12)), CASP4 (P=1.31×10(-8)), and LINC01478 (P=6.75×10(-10)) that were associated with at least 1 BP phenotype. In summary, we identified 8 novel and 1 previously reported BP loci through the examination of single-nucleotide polymorphism and gene-based interactions with sodium. PMID:27271309

  12. Influence of menstrual cycle phase on muscle metaboreflex control of cardiac baroreflex sensitivity, heart rate and blood pressure in humans.

    PubMed

    Hartwich, Doreen; Aldred, Sarah; Fisher, James P

    2013-01-01

    We sought to determine whether menstrual cycle phase influences muscle metaboreflex control of spontaneous cardiac baroreflex sensitivity (cBRS), blood pressure (BP) and heart rate (HR). Twenty-three young women not taking oral contraceptives were studied during the early (EF; low oestrogen, low progesterone) and late follicular menstrual phases (LF; high oestrogen, low progesterone). Protocol 1 consisted of leg cycling at low (21 ± 2 W) and moderate workloads (71 ± 3 W) in free-flow conditions and with partial flow restriction (bilateral thigh-cuff inflation at 100 mmHg) to activate the muscle metaboreflex. Protocol 2 consisted of rhythmic hand-grip exercise with incremental upper arm-cuff inflation (0, 80, 100 and 120 mmHg) to elicit graded metaboreflex activation. Both protocols were followed by post-exercise ischaemia. Leg cycling decreased cBRS (EF, 20 ± 5, 6 ± 1 and 1 ± 0.1 ms mmHg(-1); and LF, 19 ± 3, 6 ± 0.4, 1 ± 0.1 ms mmHg(-1) during rest, low- and moderate-intensity leg cycling, respectively) and increased HR in an intensity-dependent manner, while BP remained unchanged. Partial flow restriction during leg cycling decreased cBRS, and increased HR and BP. During post-exercise ischaemia, HR and BP remained elevated, while cBRS remained suppressed (EF, 4.2 ± 0.6 ms mmHg(-1); and LF, 4.7 ± 0.5 ms mmHg(-1); P < 0.05 versus rest). Cardiac baroreflex sensitivity was unchanged during hand-grip with and without partial flow restriction and post-exercise ischaemia. No differences in cBRS, HR or BP responses were observed between EF and LF at any time during either protocol. These data indicate that endogenous fluctuations in oestrogen between the EF and LF phases of the menstrual cycle do not influence muscle metaboreflex control of cBRS, BP or HR in young women. PMID:22613743

  13. Ionically Crosslinked Polymer Networks for Underwater Adhesion and Long-Term Controlled Release

    NASA Astrophysics Data System (ADS)

    Lawrence, Patrick G.

    Underwater adhesives have several potential applications in industry as well as in medicine. Much of the recent research in this area has focused on adhesive preparation from biological or custom-designed biomimetic polymers. As a simpler alternative, we have recently shown that ionically crosslinked, gel-like underwater adhesive complexes can be prepared by the mixing of the readily-available and inexpensive polyelectrolyte, poly(allylamine hydrochloride) (PAH), with commonly-used multivalent anions, pyrophosphate (PPi) and tripolyphosphate (TPP). Remarkably, these gel-like complexes adhere to both hydrophilic and hydrophobic substrates under water with tensile adhesive strength considerably greater than that of Scotch Permanent Double Sided Tape (up to ˜400 kPa vs. ˜85 kPa when used as a pressure-sensitive adhesives) and due to the reversible nature of the ionic crosslinks, self-heal when torn. These complexes also exhibit very high storage moduli (greater than 100 kPa), indicative of a very high crosslink density. The high crosslink density allow these gel-like complexes to also entrap and deliver small molecule payloads over multiple-month timescales. Moreover, their formation and rheological/adhesion properties can be controlled using external stimuli (pH and ionic strength). In this thesis we characterize formation and rheological/adhesion properties of gel-like PAH/PPi and PAH/TPP complexes the through the use of dynamic and electrophoretic light scattering, rheology and tensile adhesion tests. We also describe their sensitivity to pH and ionic strength, and explain how the complexes can be dissolved on demand by raising or lowering the ambient pH, and can form spontaneously by increasing the NaCl concentration (which can be used for developing injectable underwater adhesive formulations). Finally, we demonstrate the ability of these adhesives to release small molecule payloads over multiple-month timescales by characterizing their ability to take up and

  14. ATP-Sensitive Potassium (KATP) Channel Activation Decreases Intraocular Pressure in the Anterior Chamber of the Eye

    PubMed Central

    Chowdhury, Uttio Roy; Bahler, Cindy K.; Hann, Cheryl R.; Chang, Minhwang; Resch, Zachary T.; Romero, Michael F.

    2011-01-01

    Purpose. ATP-sensitive potassium channel (KATP) openers target key cellular events, many of which have been implicated in glaucoma. The authors sought to determine whether KATP channel openers influence outflow facility in human anterior segment culture and intraocular pressure (IOP) in vivo. Methods. Anterior segments from human eyes were placed in perfusion organ culture and treated with the KATP channel openers diazoxide, nicorandil, and P1075 or the KATP channel closer glyburide (glibenclamide). The presence, functionality, and specificity of KATP channels were determined by RT-PCR, immunohistochemistry, and inside-out patch clamp in human trabecular meshwork (TM) tissue or primary cultures of normal human trabecular meshwork (NTM) cells. The effect of diazoxide on IOP in anesthetized Brown Norway rats was measured with a rebound tonometer. Results. KATP channel openers increased outflow facility in human anterior segments (0.14 ± 0.02 to 0.26 ± 0.09 μL/min/mm Hg; P < 0.001) compared with fellow control eyes (0.22 ± 0.11 to 0.21 ± 0.11 μL/min/mm Hg; P > 0.5). The effect was reversible, with outflow facility returning to baseline after drug removal. The addition of glyburide inhibited diazoxide from increasing outflow facility. Electrophysiology confirmed the presence and specificity of functional KATP channels. KATP channel subunits Kir6.1, Kir6.2, SUR2A, and SUR2B were expressed in TM and NTM cells. In vivo, diazoxide significantly lowered IOP in Brown Norway rats. Conclusions. Functional KATP channels are present in the trabecular meshwork. When activated by KATP channel openers, these channels increase outflow facility through the trabecular outflow pathway in human anterior segment organ culture and decrease IOP in Brown Norway rat eyes. PMID:21743021

  15. Hydrostatic pressure activates ATP-sensitive K+ channels in lung epithelium by ATP release through pannexin and connexin hemichannels.

    PubMed

    Richter, Katrin; Kiefer, Kevin P; Grzesik, Benno A; Clauss, Wolfgang G; Fronius, Martin

    2014-01-01

    Lungs of air-breathing vertebrates are constantly exposed to mechanical forces and therefore are suitable for investigation of mechanotransduction processes in nonexcitable cells and tissues. Freshly dissected Xenopus laevis lungs were used for transepithelial short-circuit current (ISC) recordings and were exposed to increased hydrostatic pressure (HP; 5 cm fluid column, modified Ussing chamber). I(SC) values obtained under HP (I(5cm)) were normalized to values before HP (I(0cm)) application (I(5cm)/I(0cm)). Under control conditions, HP decreased I(SC) (I(5cm)/I(0cm)=0.84; n=68; P<0.0001). This effect was reversible and repeatable ≥30 times. Preincubation with ATP-sensitive K(+) channel (K(ATP)) inhibitors (HMR1098 and glibenclamide) prevented the decrease in I(SC) (I(5cm)/I(0cm): HMR1098=1.19, P<0.0001; glibenclamide=1.11, P<0.0001). Similar effects were observed with hemichannel inhibitors (I(5cm)/I(0cm): meclofenamic acid=1.09, P<0.0001; probenecid=1.0, P<0.0001). The HP effect was accompanied by release of ATP (P<0.05), determined by luciferin-luciferase luminescence in perfusion solution from the luminal side of an Ussing chamber. ATP release was abrogated by both meclofenamic acid and probenecid. RT-PCR experiments revealed the expression of pannexin and connexin hemichannels and KATP subunit transcripts in X. laevis lung. These data show an activation of KATP in pulmonary epithelial cells in response to HP that is induced by ATP release through mechanosensitive pannexin and connexin hemichannels. These findings represent a novel mechanism of mechanotransduction in nonexcitable cells. PMID:24048216

  16. PH dependent adhesive peptides

    DOEpatents

    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.

  17. Adhesive fracture mechanics. [stress analysis for bond line interface

    NASA Technical Reports Server (NTRS)

    Bennett, S. J.; Devries, K. L.; Williams, M. L.

    1974-01-01

    In studies of fracture mechanics the adhesive fracture energy is regarded as a fundamental property of the adhesive system. It is pointed out that the value of the adhesive fracture energy depends on surface preparation, curing conditions, and absorbed monolayers. A test method reported makes use of a disk whose peripheral part is bonded to a substrate material. Pressure is injected into the unbonded central part of the disk. At a certain critical pressure value adhesive failure can be observed. A numerical stress analysis involving arbitrary geometries is conducted.

  18. Fracture and adhesion of soft materials: a review

    NASA Astrophysics Data System (ADS)

    Creton, Costantino; Ciccotti, Matteo

    2016-04-01

    Soft materials are materials with a low shear modulus relative to their bulk modulus and where elastic restoring forces are mainly of entropic origin. A sparse population of strong bonds connects molecules together and prevents macroscopic flow. In this review we discuss the current state of the art on how these soft materials break and detach from solid surfaces. We focus on how stresses and strains are localized near the fracture plane and how elastic energy can flow from the bulk of the material to the crack tip. Adhesion of pressure-sensitive-adhesives, fracture of gels and rubbers are specifically addressed and the key concepts are pointed out. We define the important length scales in the problem and in particular the elasto-adhesive length Γ/E where Γ is the fracture energy and E is the elastic modulus, and how the ratio between sample size and Γ/E controls the fracture mechanisms. Theoretical concepts bridging solid mechanics and polymer physics are rationalized and illustrated by micromechanical experiments and mechanisms of fracture are described in detail. Open questions and emerging concepts are discussed at the end of the review.

  19. Fracture and adhesion of soft materials: a review.

    PubMed

    Creton, Costantino; Ciccotti, Matteo

    2016-04-01

    Soft materials are materials with a low shear modulus relative to their bulk modulus and where elastic restoring forces are mainly of entropic origin. A sparse population of strong bonds connects molecules together and prevents macroscopic flow. In this review we discuss the current state of the art on how these soft materials break and detach from solid surfaces. We focus on how stresses and strains are localized near the fracture plane and how elastic energy can flow from the bulk of the material to the crack tip. Adhesion of pressure-sensitive-adhesives, fracture of gels and rubbers are specifically addressed and the key concepts are pointed out. We define the important length scales in the problem and in particular the elasto-adhesive length Γ/E where Γ is the fracture energy and E is the elastic modulus, and how the ratio between sample size and Γ/E controls the fracture mechanisms. Theoretical concepts bridging solid mechanics and polymer physics are rationalized and illustrated by micromechanical experiments and mechanisms of fracture are described in detail. Open questions and emerging concepts are discussed at the end of the review. PMID:27007412

  20. Allergic contact dermatitis from 2-hydroxyethyl methacrylate in an adhesive on an electrosurgical earthing plate.

    PubMed

    Kanerva, L; Alanko, K

    1998-01-01

    A highly (meth)acrylate-allergic patient underwent surgery because of nodular struma. Three days after her operation she developed an itching dermatitis on her left thigh. She came to our attention 18 days after the operation, because of an oozing, highly pruritic dermatitis, 8 x 19 cm in width on her left thigh, at the site where an electrosurgical earthing plate had been used during the surgery. It was revealed that the pressure-sensitive adhesive of the pad contained 2-hydroxyethyl methacrylate (2-HEMA) to which the patient earlier had had an allergic patch test reaction. The patient was negative on patch testing to other (meth)acrylates present in the pad. Patients should be questioned about possible methacrylate sensitivity before methacrylate-containing electrosurgical earthing plates are used during surgery. Allergic contact dermatitis caused by acrylic adhesives is briefly reviewed. PMID:9854170

  1. Highly Sensitive and Multifunctional Tactile Sensor Using Free-standing ZnO/PVDF Thin Film with Graphene Electrodes for Pressure and Temperature Monitoring

    PubMed Central

    Lee, James S.; Shin, Keun-Young; Cheong, Oug Jae; Kim, Jae Hyun; Jang, Jyongsik

    2015-01-01

    We demonstrate an 80-μm-thick film (which is around 15% of the thickness of the human epidermis), which is a highly sensitive hybrid functional gauge sensor, and was fabricated from poly(vinylidene fluoride) (PVDF) and ZnO nanostructures with graphene electrodes. Using this film, we were able to simultaneously measure pressure and temperature in real time. The pressure was monitored from the change in the electrical resistance via the piezoresistance of the material, and the temperature was inferred based on the recovery time of the signal. Our thin film system enabled us to detect changes in pressure as small as 10 Pa which is pressure detection limit was 103-fold lower than the minimum level required for artificial skin, and to detect temperatures in the range 20–120°C. PMID:25601479

  2. Spatial variability and response to anthropogenic pressures of assemblages dominated by a habitat forming seaweed sensitive to pollution (northern coast of Alboran Sea).

    PubMed

    Bermejo, Ricardo; de la Fuente, Gina; Ramírez-Romero, Eduardo; Vergara, Juan J; Hernández, Ignacio

    2016-04-15

    The Cystoseira ericaefolia group is conformed by three species: C. tamariscifolia, C. mediterranea and C. amentacea. These species are among the most important habitat forming species of the upper sublittoral rocky shores of the Mediterranean Sea and adjacent Atlantic coast. This species group is sensitive to human pressures and therefore is currently suffering important losses. This study aimed to assess the influence of anthropogenic pressures, oceanographic conditions and local spatial variability in assemblages dominated by C. ericaefolia in the Alboran Sea. The results showed the absence of significant effects of anthropogenic pressures or its interactions with environmental conditions in the Cystoseira assemblages. This fact was attributed to the high spatial variability, which is most probably masking the impact of anthropogenic pressures. The results also showed that most of the variability occurred on at local levels. A relevant spatial variability was observed at regional level, suggesting a key role of oceanographic features in these assemblages. PMID:26892204

  3. Highly sensitive and multifunctional tactile sensor using free-standing ZnO/PVDF thin film with graphene electrodes for pressure and temperature monitoring.

    PubMed

    Lee, James S; Shin, Keun-Young; Cheong, Oug Jae; Kim, Jae Hyun; Jang, Jyongsik

    2015-01-01

    We demonstrate an 80-μm-thick film (which is around 15% of the thickness of the human epidermis), which is a highly sensitive hybrid functional gauge sensor, and was fabricated from poly(vinylidene fluoride) (PVDF) and ZnO nanostructures with graphene electrodes. Using this film, we were able to simultaneously measure pressure and temperature in real time. The pressure was monitored from the change in the electrical resistance via the piezoresistance of the material, and the temperature was inferred based on the recovery time of the signal. Our thin film system enabled us to detect changes in pressure as small as 10 Pa which is pressure detection limit was 10(3)-fold lower than the minimum level required for artificial skin, and to detect temperatures in the range 20-120 °C. PMID:25601479

  4. Controlled sparse and percolating cross-linking in waterborne soft adhesives.

    PubMed

    Deplace, F; Carelli, C; Langenfeld, A; Rabjohns, M A; Foster, A B; Lovell, P A; Creton, C

    2009-09-01

    The effect of low levels of cross-linking on the adhesive and mechanical properties of waterborne pressure-sensitive adhesives was investigated. We have taken advantage of a core-shell latex particle morphology obtained by emulsion polymerization to create a heterogeneous structure of cross-links without major modification of the monomer composition. The latex particles comprise a shell containing cross-linkable diacetone acrylamide (DAAM) repeat units localized on the periphery of a slightly softer core copolymer of very similar composition. Adipic acid dihydrazide was added to the latex prior to film formation to react with DAAM repeat units and affect interfacial cross-linking between particles in the adhesive films. The honeycomb-like structure obtained after drying of the latex results in a good balance between the dissipative properties required for adhesion and the resistance to creep. The characterization of the mechanical properties of the films shows that the chosen cross-linking method creates a percolating lightly cross-linked network, swollen with a nearly un-cross-linked component. With this cross-linking method, the linear viscoelastic properties of the soft films are nearly unaffected by the cross-linking while the nonlinear tensile properties are greatly modified. As a result, the long-term shear resistance of the adhesive film improves very significantly while the peel force remains nearly the same. A simple rheological model is used to interpret qualitatively the changes in the material parameters induced by cross-linking. PMID:20355828

  5. Octopus-Inspired Smart Adhesive Pads for Transfer Printing of Semiconducting Nanomembranes.

    PubMed

    Lee, Hochan; Um, Doo-Seung; Lee, Youngsu; Lim, Seongdong; Kim, Hyung-Jun; Ko, Hyunhyub

    2016-09-01

    By mimicking muscle actuation to control cavity-pressure-induced adhesion of octopus suckers, smart adhesive pads are developed in which the thermoresponsive actuation of a hydrogel layer on elastomeric microcavity pads enables excellent switchable adhesion in response to a thermal stimulus (maximum adhesive strength: 94 kPa, adhesion switching ratio: ≈293 for temperature change between 22 and 61 °C). PMID:27322886

  6. High-sensitivity nuclear magnetic resonance at Giga-Pascal pressures: a new tool for probing electronic and chemical properties of condensed matter under extreme conditions.

    PubMed

    Meier, Thomas; Haase, Jürgen

    2014-01-01

    Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their electronic properties. The application of high pressure enables one to synthesize new materials, but the response of known materials to high pressure is a very useful tool for studying their electronic structure and developing theories. For example, high-pressure synthesis might be at the origin of life; and understanding the behavior of small molecules under extreme pressure will tell us more about fundamental processes in our universe. It is no wonder that there has always been great interest in having NMR available at high pressures. Unfortunately, the desired pressures are often well into the Giga-Pascal (GPa) range and require special anvil cell devices where only very small, secluded volumes are available. This has restricted the use of NMR almost entirely in the past, and only recently, a new approach to high-sensitivity GPa NMR, which has a resonating micro-coil inside the sample chamber, was put forward. This approach enables us to achieve high sensitivity with experiments that bring the power of NMR to Giga-Pascal pressure condensed matter research. First applications, the detection of a topological electronic transition in ordinary aluminum metal and the closing of the pseudo-gap in high-temperature superconductivity, show the power of such an approach. Meanwhile, the range of achievable pressures was increased tremendously with a new generation of anvil cells (up to 10.1 GPa), that fit standard-bore NMR magnets. This approach might become a new, important tool for the investigation of many condensed matter systems, in chemistry, geochemistry, and in physics, since we can now watch structural changes with the eyes of a very versatile probe. PMID:25350694

  7. Pressure/temperature sensitive inorganic phosphors. [La/sub 2/O/sub 2/S:Eu

    SciTech Connect

    Seals, W.O.; Offen, H.W.; Turley, W.D.

    1987-01-01

    Kistler gauges are presently used to monitor pressures generated in various types of experimental tests. When a one-gallon container of stores liquid propellant was impacted by a shaped charge, hydraulic pressures in excess of 100,000 psi were produced. This destroyed the gauges. A class of inorganic phosphors, including rare earth-doped lanthanum oxysulfide (La/sub 2/O/sub 2/S:Eu) and yittrium oxysulfide (Y/sub 2/O/sub 2/S:Eu), show spectral emission characteristics that are strongly pressure dependent. The intensity of the emission lines and fluorescence decay time if individual emission lines show pressure dependence in the range of several kbar to greater than 100 kbar. These properties suggest that these phosphors could be applied as remotely operated pressure transducers. In addition phosphors show temperature dependence. This paper discusses the potential of inorganic phosphors to measure high pressure and also examines temperature effects. 5 refs., 7 figs

  8. Wind Tunnel Application of a Pressure-Sensitive Paint Technique to a Double Delta Wing Model at Subsonic and Transonic Speeds

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.; Gonzalez, Hugo A.

    2006-01-01

    A pressure-sensitive paint (PSP) technique was applied in a wind tunnel experiment in the NASA Langley Research Center 8-Foot Transonic Pressure Tunnel to study the effect of wing fillets on the global vortex induced surface static pressure field about a sharp leading-edge 76 deg./40 deg. double delta wing, or strake-wing, model at subsonic and transonic speeds. Global calibrations of the PSP were obtained at M(sub infinity) = 0.50, 0.70, 0.85, 0.95, and 1.20, a Reynolds number per unit length of 2.0 million, and angles of attack from 10 degrees to 20 degrees using an insitu method featuring the simultaneous acquisition of electronically scanned pressures (ESP) at discrete locations on the model. The mean error in the PSP measurements relative to the ESP data was approximately 2 percent or less at M(sub infinity) = 0.50 to 0.85 but increased to several percent at M(sub infinity) =0.95 and 1.20. The PSP pressure distributions and pseudo-colored, planform-view pressure maps clearly revealed the vortex-induced pressure signatures at all Mach numbers and angles of attack. Small fillets having parabolic or diamond planforms situated at the strake-wing intersection were respectively designed to manipulate the vortical flows by removing the leading-edge discontinuity or introducing additional discontinuities. The fillets caused global changes in the vortex-dominated surface pressure field that were effectively captured in the PSP measurements. The vortex surface pressure signatures were compared to available off-surface vortex cross-flow structures obtained using a laser vapor screen (LVS) flow visualization technique. The fillet effects on the PSP pressure distributions and the observed leading-edge vortex flow characteristics were consistent with the trends in the measured lift, drag, and pitching moment coefficients.

  9. Nanocapillary Adhesion between Parallel Plates.

    PubMed

    Cheng, Shengfeng; Robbins, Mark O

    2016-08-01

    Molecular dynamics simulations are used to study capillary adhesion from a nanometer scale liquid bridge between two parallel flat solid surfaces. The capillary force, Fcap, and the meniscus shape of the bridge are computed as the separation between the solid surfaces, h, is varied. Macroscopic theory predicts the meniscus shape and the contribution of liquid/vapor interfacial tension to Fcap quite accurately for separations as small as two or three molecular diameters (1-2 nm). However, the total capillary force differs in sign and magnitude from macroscopic theory for h ≲ 5 nm (8-10 diameters) because of molecular layering that is not included in macroscopic theory. For these small separations, the pressure tensor in the fluid becomes anisotropic. The components in the plane of the surface vary smoothly and are consistent with theory based on the macroscopic surface tension. Capillary adhesion is affected by only the perpendicular component, which has strong oscillations as the molecular layering changes. PMID:27413872

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  11. Orientation angle and the adhesion of single gecko setae.

    PubMed

    Hill, Ginel C; Soto, Daniel R; Peattie, Anne M; Full, Robert J; Kenny, T W

    2011-07-01

    We investigated the effects of orientation angle on the adhesion of single gecko setae using dual-axis microelectromechanical systems force sensors to simultaneously detect normal and shear force components. Adhesion was highly sensitive to the pitch angle between the substrate and the seta's stalk. Maximum lateral adhesive force was observed with the stalk parallel to the substrate, and adhesion decreased smoothly with increasing pitch. The roll orientation angle only needed to be roughly correct with the spatular tuft of the seta oriented grossly towards the substrate for high adhesion. Also, detailed measurements were made to control for the effect of normal preload forces. Higher normal preload forces caused modest enhancement of the observed lateral adhesive force, provided that adequate contact was made between the seta and the substrate. These results should be useful in the design and manufacture of gecko-inspired synthetic adhesives with anisotropic properties, an area of substantial recent research efforts. PMID:21288955

  12. Orientation angle and the adhesion of single gecko setae

    PubMed Central

    Hill, Ginel C.; Soto, Daniel R.; Peattie, Anne M.; Full, Robert J.; Kenny, T. W.

    2011-01-01

    We investigated the effects of orientation angle on the adhesion of single gecko setae using dual-axis microelectromechanical systems force sensors to simultaneously detect normal and shear force components. Adhesion was highly sensitive to the pitch angle between the substrate and the seta's stalk. Maximum lateral adhesive force was observed with the stalk parallel to the substrate, and adhesion decreased smoothly with increasing pitch. The roll orientation angle only needed to be roughly correct with the spatular tuft of the seta oriented grossly towards the substrate for high adhesion. Also, detailed measurements were made to control for the effect of normal preload forces. Higher normal preload forces caused modest enhancement of the observed lateral adhesive force, provided that adequate contact was made between the seta and the substrate. These results should be useful in the design and manufacture of gecko-inspired synthetic adhesives with anisotropic properties, an area of substantial recent research efforts. PMID:21288955

  13. Characterizing cell adhesion by using micropipette aspiration.

    PubMed

    Hogan, Brenna; Babataheri, Avin; Hwang, Yongyun; Barakat, Abdul I; Husson, Julien

    2015-07-21

    We have developed a technique to directly quantify cell-substrate adhesion force using micropipette aspiration. The micropipette is positioned perpendicular to the surface of an adherent cell and a constant-rate aspiration pressure is applied. Since the micropipette diameter and the aspiration pressure are our control parameters, we have direct knowledge of the aspiration force, whereas the cell behavior is monitored either in brightfield or interference reflection microscopy. This setup thus allows us to explore a range of geometric parameters, such as projected cell area, adhesion area, or pipette size, as well as dynamical parameters such as the loading rate. We find that cell detachment is a well-defined event occurring at a critical aspiration pressure, and that the detachment force scales with the cell adhesion area (for a given micropipette diameter and loading rate), which defines a critical stress. Taking into account the cell adhesion area, intrinsic parameters of the adhesion bonds, and the loading rate, a minimal model provides an expression for the critical stress that helps rationalize our experimental results. PMID:26200857

  14. Characterizing Cell Adhesion by Using Micropipette Aspiration

    PubMed Central

    Hogan, Brenna; Babataheri, Avin; Hwang, Yongyun; Barakat, Abdul I.; Husson, Julien

    2015-01-01

    We have developed a technique to directly quantify cell-substrate adhesion force using micropipette aspiration. The micropipette is positioned perpendicular to the surface of an adherent cell and a constant-rate aspiration pressure is applied. Since the micropipette diameter and the aspiration pressure are our control parameters, we have direct knowledge of the aspiration force, whereas the cell behavior is monitored either in brightfield or interference reflection microscopy. This setup thus allows us to explore a range of geometric parameters, such as projected cell area, adhesion area, or pipette size, as well as dynamical parameters such as the loading rate. We find that cell detachment is a well-defined event occurring at a critical aspiration pressure, and that the detachment force scales with the cell adhesion area (for a given micropipette diameter and loading rate), which defines a critical stress. Taking into account the cell adhesion area, intrinsic parameters of the adhesion bonds, and the loading rate, a minimal model provides an expression for the critical stress that helps rationalize our experimental results. PMID:26200857

  15. Modeling and analysis of a novel combined peninsula-island structure diaphragm for ultra-low pressure sensing with high sensitivity

    NASA Astrophysics Data System (ADS)

    Xu, Tingzhong; Zhao, Libo; Jiang, Zhuangde; Xu, Yu; Zhao, Yulong

    2016-02-01

    A novel combined peninsula-island structure diaphragm has been developed with four pairs of peninsula and island structures as well as four gaps between them. When a pressure is applied to the diaphragm, the major strain energy of the diaphragm is locked in the position above each gap, which is called the stress concentration region (SCR). Also, minimal strain energy is wasted outside the SCR. Therefore, this novel diaphragm is favorable in obtaining high sensitivity for a micro-electromechanical system piezoresistive ultra-low pressure sensor. In order to optimize the diaphragm structure, the partial differential equation governing the diaphragm deflection has been given under pressure. The theoretical analysis solutions are obtained based on the theory of the Navier trigonometric series and the mirror image method, and in accordance with the finite element method simulation results. Finally, a sensor with the proposed diaphragm is designed with the working range of 0-500 Pa and has sensitivity above 0.055 mV V-1 Pa-1. In comparison to a flat diaphragm with the same dimensions, this novel diaphragm achieves a sensitivity level increased by 256%, a nonlinearity reduced by 79%, and a resonance frequency increased by 5.5%. In addition, the proposed theoretical analysis solution of the diaphragm can also be applied to other kinds of diaphragm with different islands to achieve optimization.

  16. Correlation among soluble receptors for advanced glycation end-products, soluble vascular adhesion protein-1/semicarbazide-sensitive amine oxidase (sVAP-1) and cardiometabolic risk markers in apparently healthy adolescents: a cross-sectional study.

    PubMed

    Gurecká, Radana; Koborová, Ivana; Csongová, Melinda; Šebek, Jozef; Šebeková, Katarína

    2016-08-01

    In non-diabetics, low levels of soluble receptor for advanced glycations end products (sRAGE) associate with an increased risk of development of diabetes, cardiovascular afflictions, or death. The majority of studies in non-diabetics report an inverse relationship between measures of obesity, cardiometabolic risk factors and sRAGE and/or endogenous secretory RAGE (esRAGE) levels. To elucidate whether this inconsistency is related to the metabolically healthy obese phenotype, or a different impact of the risk factors in presence and absence of obesity, we analyzed data from 2206 apparently healthy adolescents (51 % girls) aged 15-to-19 years. The association of sRAGE levels with soluble vascular adhesion protein-1/semicarbazide sensitive amine oxidase (sVAP-1/SSAO) was also investigated. Centrally obese, including metabolically healthy, adolescents present significantly lower sRAGE and esRAGE, but not sVAP-1, levels in comparison with their lean counterparts. An increasing number of cardiometabolic risk factors did not associate with significant changes in sRAGE, esRAGE or sVAP-1 levels either in lean or in obese subjects. In multivariate analyses, WHtR, hsCRP, markers of glucose homeostasis, renal function, adiponectin, and sVAP-1 associated significantly with sRAGE and esRAGE. SVAP-1 correlated significantly with glycemia, adiponectin, hsCRP, and sRAGE. Thus, in adolescents, a decline in sRAGE and esRAGE precedes the development of metabolic syndrome. When combined, standard and non-standard cardiometabolic risk factors explain only minor proportion in a variability of sRAGE and esRAGE (8 %-11 %); or sVAP-1 (12 %-20 %). Elucidation of pathogenetic mechanisms underlying early decline in sRAGE and esRAGE levels in obese adolescents and their clinical impact with regard to future cardiometabolic health requires further studies. PMID:27300745

  17. Interplay between viscoelastic and chemical tunings in fatty-acid-based polyester adhesives: engineering biomass toward functionalized step-growth polymers and soft networks.

    PubMed

    Vendamme, Richard; Olaerts, Katrien; Gomes, Monica; Degens, Marc; Shigematsu, Takayuki; Eevers, Walter

    2012-06-11

    This Article describes the synthesis and characterization of renewable self-adhesive coatings with tunable viscoelastic properties and equipped with well-defined amounts of carboxylic acid "sticker" groups with adhesion promoting characteristics. Hydroxyl-ended polyesters with various architectures (linear, branched) were synthesized by melt polycondensation of dimerized fatty acids and fatty diols and then cured with maleic anhydride-modified triglycerides (such as maleinized soybean oil) in the presence of the amidine catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene. The curing reaction of alcoholysis has the dual effect of chain extending/cross-linking the base polymers via creation of polymeric half-esters linkages while introducing carboxylic acid functions within the gel structure. We demonstrated how the adhesion properties can be finely tuned from molecular design and formulation of the network precursors and how the rheology and functionality of the coatings influence the adhesive bond formation and development. These renewable polyester adhesives proved to be suitable materials for pressure-sensitive adhesives applications with respect to adhesion strength, viscoelasticity, and functionality. In addition, the environmental benefits of such materials are briefly discussed. PMID:22612310

  18. Unified Application Vapor Screen Flow Visualization and Pressure Sensitive Paint Measurement Techniques to Vortex- and Shock Wave-Dominated Flow Fields

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.

    2008-01-01

    Laser vapor screen (LVS) flow visualization and pressure sensitive paint (PSP) techniques were applied in a unified approach to wind tunnel testing of slender wing and missile configurations dominated by vortex flows and shock waves at subsonic, transonic, and supersonic speeds. The off-surface cross-flow patterns using the LVS technique were combined with global PSP surface static pressure mappings to characterize the leading-edge vortices and shock waves that coexist and interact at high angles of attack (alpha). The synthesis of LVS and PSP techniques was also effective in identifying the significant effects of passive surface porosity and the presence of vertical tail surfaces on the flow topologies. An overview is given of LVS and PSP applications in selected experiments on small-scale models of generic slender wing and missile configurations in the NASA Langley Research Center (NASA LaRC) Unitary Plan Wind Tunnel (UPWT) and 8-Foot Transonic Pressure Tunnel (8-Foot TPT).

  19. Unified Application of Vapor Screen Flow Visualization and Pressure Sensitive Paint Measurement Techniques to Vortex- and Shock Wave-Dominated Flow Fields

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.

    2010-01-01

    Laser vapor screen (LVS) flow visualization and pressure sensitive paint (PSP) techniques were applied in a unified approach to wind tunnel testing of slender wing and missile configurations dominated by vortex flows and shock waves at subsonic, transonic, and supersonic speeds. The off-surface cross-flow patterns using the LVS technique were combined with global PSP surface static pressure mappings to characterize the leading-edge vortices and shock waves that coexist and interact at high angles of attack. The synthesis of LVS and PSP techniques was also effective in identifying the significant effects of passive surface porosity and the presence of vertical tail surfaces on the flow topologies. An overview is given of LVS and PSP applications in selected experiments on small-scale models of generic slender wing and missile configurations in the NASA Langley Research Center (NASA LaRC) Unitary Plan Wind Tunnel (UPWT) and 8-Foot Transonic Pressure Tunnel (8-Foot TPT).

  20. Peritoneal adhesions after laparoscopic gastrointestinal surgery

    PubMed Central

    Mais, Valerio

    2014-01-01

    Although laparoscopy has the potential to reduce peritoneal trauma and post-operative peritoneal adhesion formation, only one randomized controlled trial and a few comparative retrospective clinical studies have addressed this issue. Laparoscopy reduces de novo adhesion formation but has no efficacy in reducing adhesion reformation after adhesiolysis. Moreover, several studies have suggested that the reduction of de novo post-operative adhesions does not seem to have a significant clinical impact. Experimental data in animal models have suggested that CO2 pneumoperitoneum can cause acute peritoneal inflammation during laparoscopy depending on the insufflation pressure and the surgery duration. Broad peritoneal cavity protection by the insufflation of a low-temperature humidified gas mixture of CO2, N2O and O2 seems to represent the best approach for reducing peritoneal inflammation due to pneumoperitoneum. However, these experimental data have not had a significant impact on the modification of laparoscopic instrumentation. In contrast, surgeons should train themselves to perform laparoscopy quickly, and they should complete their learning curves before testing chemical anti-adhesive agents and anti-adhesion barriers. Chemical anti-adhesive agents have the potential to exert broad peritoneal cavity protection against adhesion formation, but when these agents are used alone, the concentrations needed to prevent adhesions are too high and could cause major post-operative side effects. Anti-adhesion barriers have been used mainly in open surgery, but some clinical data from laparoscopic surgeries are already available. Sprays, gels, and fluid barriers are easier to apply in laparoscopic surgery than solid barriers. Results have been encouraging with solid barriers, spray barriers, and gel barriers, but they have been ambiguous with fluid barriers. Moreover, when barriers have been used alone, the maximum protection against adhesion formation has been no greater than

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

    PubMed

    Heepe, Lars; Kovalev, Alexander E; Gorb, Stanislav N

    2014-01-01

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

  2. Effect of metal surface characteristics on the adhesion performance of the integrated low-level energies method of adhesion.

    PubMed

    Aodai, Toshiyuki; Masuzawa, Toru; Ozeki, Kazuhide; Kishida, Akio; Higami, Tetsuya

    2012-12-01

    We have previously proposed a new method of adhesion using the integrated low-level energy sources heat, vibration, and pressure. This adhesion method can be used to attach biological tissue to a metal object. Effects of surface roughness and energy of the metal subject on adhesion performance were studied by using commercially pure titanium (cpTi) and stainless steel (SUS304). Surface roughness and energy were changed by sandblast treatment and heat treatment, respectively. A porcine aorta was adhered to sandblast-treated SUS304 by use of an adhesion temperature of 80 °C, a vibration amplitude of 15 μm, a pressure of 2.5 MPa, an adhesion time of 120 s, and a surface roughness of an Ra 0.25 μm. The shear tensile strength of the adhesion was 0.45 MPa. The adhesion performance was improved by roughening the surface of the metal specimen. Surface energy has an insignificant effect on adhesive strength. The adhesion performance varied depending on metal material for the same surface roughness, Ra, and energy. Results from analysis of the surface roughness profile suggested that the size of surface asperity has an effect on adhesion performance. PMID:22933053

  3. 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.

  4. 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.

  5. Underwater Adhesives Retrofit Pipelines with Advanced Sensors

    NASA Technical Reports Server (NTRS)

    2015-01-01

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

  6. The sensitivity of cartilage contact pressures in the knee joint to the size and shape of an anatomically shaped meniscal implant.

    PubMed

    Khoshgoftar, M; Vrancken, A C T; van Tienen, T G; Buma, P; Janssen, D; Verdonschot, N

    2015-06-01

    Since meniscal geometry affects the cartilage contact pressures, it is essential to carefully define the geometry of the synthetic meniscal implant that we developed. Recently, six independent modes of size- and shape-related geometry variation were identified through 3D statistical shape modeling (SSM) of the medial meniscus. However, this model did not provide information on the functional importance of these geometry characteristics. Therefore, in this study finite element simulations were performed to determine the influence of anatomically-based meniscal implant size and shape variations on knee cartilage contact pressures. Finite element simulations of the knee joint were performed for a total medial meniscectomy, an allograft, the average implant geometry, six implant sizes and ten shape variations. The geometries of the allograft and all implant variations were based on the meniscus SSM. Cartilage contact pressures and implant tensile strains were evaluated in full extension under 1200N of axial compression. The average implant induced cartilage peak pressures intermediate between the allograft and meniscectomy and also reduced the cartilage area subjected to pressures >5MPa compared to the meniscectomy. The smaller implant sizes resulted in lower cartilage peak pressures and compressive strains than the allograft, yet high implant tensile strains were observed. Shape modes 2, 3 and 6 affected the cartilage contact stresses but to a lesser extent than the size variations. Shape modes 4 and 5 did not result in changes of the cartilage stress levels. The present study indicates that cartilage contact mechanics are more sensitive to implant size than to implant shape. Down-sizing the implant resulted in more favorable contact mechanics, but caused excessive material strains. Further evaluations are necessary to balance cartilage contact pressures and material strains to ensure cartilage protection and longevity of the implant. PMID:25766390

  7. Nondestructive testing of adhesive bonds by nuclear quadrupole resonance method

    NASA Technical Reports Server (NTRS)

    Hewitt, R. R.

    1971-01-01

    Inert, strain sensitive tracer, cuprous oxide, added to polymeric adhesive ensures sufficiently large signal to noise ratio in NQR system output. Method is successful, provided that RF-transparent structural materials are used between modified adhesive and probe of NQR spectrometer.

  8. Postoperative Peritoneal Adhesions

    PubMed Central

    Ryan, Graeme B.; Grobéty, Jocelyne; Majno, Guido

    1971-01-01

    This paper describes an experimental model of peritoneal adhesions, in the rat, based on two relatively minor accidents that may occur during abdominal surgery in man: drying of the serosa, and bleeding. Drying alone had little effect; drying plus bleeding consistently produced adhesions to the dried area. Fresh blood alone produced adhesions between the three membranous structures [omentum and pelvic fat bodies (PFBs)]. The formation of persistent adhesions required whole blood. Preformed clots above a critical size induced adhesions even without previous serosal injury; they were usually captured by the omentum and PFBs. If all three membranous structures were excised, the clots caused visceral adhesions. The protective role of the omentum, its structure, and the mechanism of omental adhesions, are discussed. These findings are relevant to the pathogenesis of post-operative adhesions in man. ImagesFig 3Fig 4Fig 5Fig 6Fig 7Fig 12Fig 13Fig 1Fig 2Fig 14Fig 15Fig 8Fig 9Fig 10Fig 11 PMID:5315369

  9. Pressure Controller

    NASA Astrophysics Data System (ADS)

    1981-01-01

    EPIC is Electronic Pressure Indicating Controller produced by North American Manufacturing Company. It is a high-sensitivity device for improving combustion efficiency in industrial furnaces that interprets a signal from a pressure transducer on a furnace and regulates furnace pressure accordingly. A controller can provide savings of from five to 25 percent of an industrial user's annual furnace fuel bill.

  10. Constant pressure-assisted head-column field-amplified sample injection in combination with in-capillary derivatization for enhancing the sensitivity of capillary electrophoresis.

    PubMed

    Yan, Na; Zhou, Lei; Zhu, Zaifang; Zhang, Huige; Zhou, Ximin; Chen, Xingguo

    2009-05-15

    In this work, a novel method combining constant pressure-assisted head-column field-amplified sample injection (PA-HC-FASI) with in-capillary derivatization was developed for enhancing the sensitivity of capillary electrophoresis. PA-HC-FASI uses an appropriate positive pressure to counterbalance the electroosmotic flow in the capillary column during electrokinetic injection, while taking advantage of the field amplification in the sample matrix and the water of the "head column". Accordingly, the analytes were stacked at the stationary boundary between water and background electrolyte. After 600s PA-HC-FASI, 4-fluoro-7-nitro-2,1,3-benzoxadiazole as derivatization reagent was injected, followed by an electrokinetic step (5kV, 45s) to enhance the mixing efficiency of analytes and reagent plugs. Standing a specified time of 10min for derivatization reaction under 35 degrees C, then the capillary temperature was cooled to 25 degrees C and the derivatives were immediately separated and determined under 25 degrees C. By investigating the variables of the presented approach in detail, on-line preconcentration, derivatization and separation could be automatically operated in one run and required no modification of current CE commercial instrument. Moreover, the sensitivity enhancement factor of 520 and 800 together with the detection limits of 16.32 and 6.34pg/mL was achieved for model compounds: glufosinate and aminomethylphosphonic acid, demonstrating the high detection sensitivity of the presented method. PMID:19342058

  11. Evaluation of polyaryl adhesives in elastomer-stainless steel joints

    SciTech Connect

    Miura, M.; Carciello, N.; Sugama, T.; Kukacka, L.E.

    1992-10-01

    Polyaryl thermoplastic adhesives (polyetheretherketone, PEEK, polyphenylene sulfide PPS, polyphenylethersulfone, PES) were evaluated for ability to bond elastomer to metal for use in geothermal environments. Strength of elastomer-to-metal joints adhesives blends (such as in drill pipe or casing protectors) were determined using peel tests. Parameters involved in making the joints were temperature, time and atmosphere, in addition to type of adhesive. Physical chemical analyses have aided endeavors to determine the cause of adhesion failure in the joint: differential thermal analyses, thermal gravimetric analyses, infrared spectroscopy and electron spectroscopy for chemical analysis. Tests showed that joints made of adhesive blends which contained greater than 50% PES survived simulated geothermal conditions (200C, water vapor pressure 200 psi) for weeks without significant decrease in peel strength. Chemical components of the adhesive appear to be highly stable under the conditions required to make the joints and in subsequent exposure to the simulated geothermal environment.

  12. Deployment of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades in Simulated Forward Flight: Preliminary PSP Results from Test 581 in the 14- by 22-Foot Subsonic Tunnel

    NASA Technical Reports Server (NTRS)

    Watkins, Anthony Neal; Leighty, Bradley D.; Lipford, William E.; Wong, Oliver D.; Goodman, Kyle Z.; Crafton, James; Forlines, Alan; Goss, Larry; Gregory, James W.; Juliano, Thomas J.

    2011-01-01

    This report will present details of a Pressure Sensitive Paint (PSP) system for measuring global surface pressures on the tips of rotorcraft blades in simulated forward flight at the 14- x 22-Foot Subsonic Tunnel. The system was designed to use a pulsed laser as an excitation source and PSP data was collected using the lifetime-based approach. With the higher intensity of the laser, this allowed PSP images to be acquired during a single laser pulse, resulting in the collection of crisp images that can be used to determine blade pressure at a specific instant in time. This is extremely important in rotorcraft applications as the blades experience dramatically different flow fields depending on their position in the rotor disk. Testing of the system was performed using the U.S. Army General Rotor Model System equipped with four identical blades. Two of the blades were instrumented with pressure transducers to allow for comparison of the results obtained from the PSP. This report will also detail possible improvements to the system.

  13. Numerical investigation of a coupled moving boundary model of radial flow in low-permeable stress-sensitive reservoir with threshold pressure gradient

    NASA Astrophysics Data System (ADS)

    Wen-Chao, Liu; Yue-Wu, Liu; Cong-Cong, Niu; Guo-Feng, Han; Yi-Zhao, Wan

    2016-02-01

    The threshold pressure gradient and formation stress-sensitive effect as the two prominent physical phenomena in the development of a low-permeable reservoir are both considered here for building a new coupled moving boundary model of radial flow in porous medium. Moreover, the wellbore storage and skin effect are both incorporated into the inner boundary conditions in the model. It is known that the new coupled moving boundary model has strong nonlinearity. A coordinate transformation based fully implicit finite difference method is adopted to obtain its numerical solutions. The involved coordinate transformation can equivalently transform the dynamic flow region for the moving boundary model into a fixed region as a unit circle, which is very convenient for the model computation by the finite difference method on fixed spatial grids. By comparing the numerical solution obtained from other different numerical method in the existing literature, its validity can be verified. Eventually, the effects of permeability modulus, threshold pressure gradient, wellbore storage coefficient, and skin factor on the transient wellbore pressure, the derivative, and the formation pressure distribution are analyzed respectively. Project supported by the National Natural Science Foundation of China (Grant No. 51404232), the China Postdoctoral Science Foundation (Grant No. 2014M561074), and the National Science and Technology Major Project, China (Grant No. 2011ZX05038003).

  14. Shear adhesion strength of aligned electrospun nanofibers.

    PubMed

    Najem, Johnny F; Wong, Shing-Chung; Ji, Guang

    2014-09-01

    Inspiration from nature such as insects' foot hairs motivates scientists to fabricate nanoscale cylindrical solids that allow tens of millions of contact points per unit area with material substrates. In this paper, we present a simple yet robust method for fabricating directionally sensitive shear adhesive laminates. By using aligned electrospun nylon-6, we create dry adhesives, as a succession of our previous work on measuring adhesion energies between two single free-standing electrospun polymer fibers in cross-cylinder geometry, randomly oriented membranes and substrate, and peel forces between aligned fibers and substrate. The synthetic aligned cylindrical solids in this study are electrically insulating and show a maximal Mode II shear adhesion strength of 27 N/cm(2) on a glass slide. This measured value, for the purpose of comparison, is 270% of that reported from gecko feet. The Mode II shear adhesion strength, based on a commonly known "dead-weight" test, is 97-fold greater than the Mode I (normal) adhesion strength of the same. The data indicate a strong shear binding on and easy normal lifting off. Anisotropic adhesion (Mode II/Mode I) is pronounced. The size and surface boundary effects, crystallinity, and bending stiffness of fibers are used to understand these electrospun nanofibers, which vastly differ from otherwise known adhesive technologies. The anisotropic strength distribution is attributed to a decreasing fiber diameter and an optimized laminate thickness, which, in turn, influences the bending stiffness and solid-state "wettability" of points of contact between nanofibers and surface asperities. PMID:25105533

  15. Enhanced friction of elastomer microfiber adhesives with spatulate tips

    NASA Astrophysics Data System (ADS)

    Kim, Seok; Aksak, Burak; Sitti, Metin

    2007-11-01

    Previous studies have demonstrated that gecko foot-hair inspired elastomer microfibers with spatulate tips have significant adhesion enhancement compared to the flat elastomer surface. In this study, we report the friction enhancement of these highly adhesive fibers and analyze the relation between adhesion and friction of elastomer microfiber arrays with spatulate tips. Fabricated polyurethane fiber arrays with spatulate tips demonstrate macroscale static friction pressures up to 41N/cm2 for a preload pressure of 1.5N/cm2 on a 6mm diameter smooth glass hemisphere.

  16. Low-intensity voluntary running lowers blood pressure with simultaneous improvement in endothelium-dependent vasodilatation and insulin sensitivity in aged spontaneously hypertensive rats.

    PubMed

    Sun, Meng-Wei; Qian, Feng-Lei; Wang, Jian; Tao, Tao; Guo, Jing; Wang, Lie; Lu, Ai-Yun; Chen, Hong

    2008-03-01

    Our objective is to examine the effects of voluntary running at different intensity levels on blood pressure, endothelium-dependent vessel dysfunction and insulin resistance in aged spontaneously hypertensive rats (SHR) with severe hypertension. Ten-month-old male and female SHR with severe hypertension were assigned to voluntary running at either low intensity (30% of maximal aerobic velocity) or moderate intensity (60% of maximal aerobic velocity) on a motor-driven treadmill for 6 weeks, 20 min per day and 7 days per week. Age-matched Wistar-Kyoto rats and SHR were kept under sedentary conditions as controls. Blood pressure and heart rate were measured by the tail-cuff method. At the end of the exercise training, blood samples were collected for glucose, insulin and lipids assay, and aortae were isolated to examine their function in vitro. Low-intensity but not moderate-intensity running significantly lowered blood pressure in both male and female SHR (p<0.01). There was significant impairment in acetylcholine-induced vasorelaxation in SHR (p<0.01), which was improved by low-intensity training (p<0.05). Nitric oxide synthase blockade abrogated the improvement in endothelium-dependent relaxation. Hypertensive rats had elevated blood glucose and insulin levels with lowered insulin sensitivity that was ameliorated by low-intensity running. A significant increase in blood high-density lipoprotein (HDL)-cholesterol and a significant decrease in triglycerides were found in exercised SHR. In conclusion, low-intensity voluntary exercise lowers hypertension in aged SHR with severe hypertension. Exercise-induced simultaneous improvement in endothelium-dependent vessel relaxation and insulin sensitivity may act concomitantly in attenuating cardiovascular risk factors in aged hypertensive rats with significantly high blood pressure. PMID:18497475

  17. 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. PMID:20844908

  18. Surgical Adhesives in Facial Plastic Surgery.

    PubMed

    Toriumi, Dean M; Chung, Victor K; Cappelle, Quintin M

    2016-06-01

    In facial plastic surgery, attaining hemostasis may require adjuncts to traditional surgical techniques. Fibrin tissue adhesives have broad applications in surgery and are particularly useful when addressing the soft tissue encountered in facial plastic surgery. Beyond hemostasis, tissue adhesion and enhanced wound healing are reported benefits associated with a decrease in operating time, necessity for drains and pressure dressings, and incidence of wound healing complications. These products are clinically accessible to most physicians who perform facial plastic surgery, including skin grafts, flaps, rhytidectomy, and endoscopic forehead lift. PMID:27267012

  19. 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

  20. Cell adhesion force microscopy

    PubMed Central

    Sagvolden, G.; Giaever, I.; Pettersen, E. O.; Feder, J.

    1999-01-01

    The adhesion forces of cervical carcinoma cells in tissue culture were measured by using the manipulation force microscope, a novel atomic force microscope. The forces were studied as a function of time and temperature for cells cultured on hydrophilic and hydrophobic polystyrene substrates with preadsorbed proteins. The cells attached faster and stronger at 37°C than at 23°C and better on hydrophilic than on hydrophobic substrates, even though proteins adsorb much better to the hydrophobic substrates. Because cell adhesion serves to control several stages in the cell cycle, we anticipate that the manipulation force microscope can help clarify some cell-adhesion related issues. PMID:9892657

  1. 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.

  2. Adhesions and Healing of Intestinal Anastomoses: The Effect of Anti-Adhesion Barriers.

    PubMed

    Ntourakis, Dimitrios; Katsimpoulas, Michail; Tanoglidi, Anna; Barbatis, Calypso; Karayannacos, Panayotis E; Sergentanis, Theodoros N; Kostomitsopoulos, Nikolaos; Machairas, Anastasios

    2016-06-01

    Background Postoperative adhesions are the result of aberrant peritoneal healing. As they are the leading cause of postoperative bowel obstruction, anti-adherence barriers are advocated for their prevention. This study looks into the effect of these biomaterials on the healing of intestinal anastomoses. Materials and Methods Thirty-three New Zealand White rabbits underwent laparotomy, transection of the terminal ileum, and creation of an end-to-end anastomosis. Animals were randomized into 3 groups: the Control group (n = 11); the Icodextrin group, receiving icodextrin 4% intraperitonealy (n = 11); and the HA/CMC group, having the anastomosis wrapped with a hyaluronic acid/carboxymethylcellulose film (n = 11). All animals were sacrificed on the seventh postoperative day. Macroscopic adhesions were graded and anastomotic strength was tested by the burst pressure. Histological healing was assessed in a semiquantitative way for the presence of ulceration, reepithelization, granulation tissue, inflammation, eosinophilic infiltration, serosal inflammation, and microscopic adhesions. Univariate and multivariate analysis was used. Results are given as medians with interquartile range. Results The median adhesion scores were the following: Control 1 (0-3), Icodextrin 0 (0-1), HA/CMC 0 (0-0), P = .017. The burst pressure did not differ between the groups; however, all except one bowel segments tested burst away from the anastomosis. The macroscopic and histological anastomotic healing was comparable in all 3 groups. A poor histological anastomotic healing score was associated with a higher adhesion grade (odds ratio = 1.92; 95% confidence interval = 1.06-3.47; P = .032). Conclusion Adhesion formation was inhibited by the materials tested without direct detrimental effects on anastomotic healing. Poor anastomotic healing provokes adhesions even in the presence of anti-adhesion barriers. PMID:26474604

  3. 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

  4. 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

  5. Pressure-assisted electrokinetic injection stacking for verteporfin drug to achieve highly sensitive enantioseparation and detection in artificial urine by capillary electrophoresis.

    PubMed

    Xu, Zhongqi; Li, Aimei; Wang, Yongle; Chen, Zhilong; Hirokawa, Takeshi

    2014-08-15

    Pressure-assisted electrokinetic injection (PAEKI) was applied for negatively charged verteporfin (VER) overloading and inline stacking, which targeted highly sensitive enantioseparation by CE. The essential step of PAEKI is a constant pressure used to counterbalance the electroosmotic flow (EOF), consequently, the large amount of analyte could be permitted into capillary and concentrated at the motionless boundary of the sample zone and background electrolyte (BGE). Aiming to know the balance, the velocity of the whole BGE in capillary by the impetus of pressure (0.2-2.0psi), and the velocity of EOF depending on the length of sample plug and voltage (5.0-20kV) was investigated, respectively. The velocity of bulk flow in capillary has good linearity with the pressure or applied voltage. Through the pattern of EOF marked peak and analyte peaks (dissolved in pure water), the constant pressure (0.8psi) vs. the added voltage (-10.3kV) during PAEKI was confirmed to immobilize the bulk flow of BGE, thus the sample injection time could sustain 2.0min without compromising separation efficiency. The obtained LOD (S/N=3) of each isomer at UV detection (428nm) was around 10.3μg/L, which was improved to 116 and 39-fold in comparison with normal hydrodynamic injection (HDI) and electrokinetic injection (EKI). The LOD is far below the reported value with LIF detection of VER. The RSD (n=5) of migration time and peak area was, respectively, around 3.5% and 5.7% for the proposed PAEKI method. Finally, PAEKI was used for the detection of VER in artificial urine to investigate the matrix interference. PMID:24951290

  6. Direct Pen Writing of Adhesive Particle-Free Ultrahigh Silver Salt-Loaded Composite Ink for Stretchable Circuits.

    PubMed

    Hu, Mingjun; Cai, Xiaobing; Guo, Qiuquan; Bian, Bin; Zhang, Tengyuan; Yang, Jun

    2016-01-26

    In this article, we describe a writable particle-free ink for fast fabrication of highly conductive stretchable circuits. The composite ink mainly consists of soluble silver salt and adhesive rubber. Low toxic ketone was employed as the main solvent. Attributed to ultrahigh solubility of silver salt in short-chain ketone and salt-assisted dissolution of rubber, the ink can be prepared into particle-free transparent solution. As-prepared ink has a good chemical stability and can be directly filled into ballpoint pens and use to write on different substrates to form well adhesive silver salt-based composite written traces as needed. As a result of high silver salt loading, the trace can be converted into highly conductive silver nanoparticle-based composites after in situ reduction. Because of the introduction of adhesive elastomeric rubber, the as-formed conductive composite written trace can not only maintain good adhesion to various substrates but also show good conductivity under various deformations. The conductivity of written traces can be enhanced by repeated writing-reduction cycles. Different patterns can be fabricated by either direct handwriting or hand-copying. As proof-of-concept demonstrations, a typical handwriting heart-like circuit was fabricated to show its capability to work under different deformations, and a pressure-sensitive switch was also manufactured to present pressure-dependent change of resistance. PMID:26624508

  7. 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.

  8. 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.

  9. Adhesion of Lunar Dust

    NASA Astrophysics Data System (ADS)

    Walton, Otis R.

    2007-04-01

    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.

  10. 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.

  11. Leucocyte cellular adhesion molecules.

    PubMed

    Yong, K; Khwaja, A

    1990-12-01

    Leucocytes express adhesion promoting receptors which mediate cell-cell and cell-matrix interactions. These adhesive interactions are crucial to the regulation of haemopoiesis and thymocyte maturation, the direction and control of leucocyte traffic and migration through tissues, and in the development of immune and non-immune inflammatory responses. Several families of adhesion receptors have been identified (Table). The leucocyte integrin family comprises 3 alpha beta heterodimeric membrane glycoproteins which share a common beta subunit, designated CD18. The alpha subunits of each of the 3 members, lymphocyte function associated antigen-1 (LFA-1), macrophage antigen-1 (Mac-1) and p150,95 are designated CD11a, b and c respectively. These adhesion molecules play a critical part in the immune and inflammatory responses of leucocytes. The leucocyte integrin family is, in turn, part of the integrin superfamily, members of which are evolutionally, structurally and functionally related. Another Integrin subfamily found on leucocytes is the VLA group, so-called because the 'very late activation antigens' VLA-1 and VLA-2 were originally found to appear late in T-cell activation. Members of this family function mainly as extracellular matrix adhesion receptors and are found both on haemopoietic and non-haemopoietic cells. They play a part in diverse cellular functions including tissue organisation, lymphocyte recirculation and T-cell immune responses. A third integrin subfamily, the cytoadhesins, are receptors on platelets and endothelial cells which bind extracellular matrix proteins. A second family of adhesion receptors is the immunoglobulin superfamily, members of which include CD2, LFA-3 and ICAM-1, which participate in T-cell adhesive interactions, and the antigen-specific receptors of T and B cells, CD4, CD8 and the MHC Class I and II molecules. A recently recognised family of adhesion receptors is the selectins, characterised by a common lectin domain. Leucocyte

  12. High temperature adhesives

    NASA Technical Reports Server (NTRS)

    St.clair, Terry L.

    1991-01-01

    The aerospace and electronics industries have an ever increasing need for higher performance materials. In recent years, linear aromatic polyimides have been proven to be a superior class of materials for various applications in these industries. The use of this class of polymers as adhesives is continuing to increase. Several NASA Langley developed polyimides show considerable promise as adhesives because of their high glass transition temperatures, thermal stability, resistance to solvents/water, and their potential for cost effective manufacture.

  13. Adhesive capsulitis of the hip: a review.

    PubMed

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

    2013-12-01

    Adhesive capsulitis of the hip (ACH) is a rare clinical entity. Similar to adhesive capsulitis of the shoulder, ACH is characterized by a painful decrease in active and passive range of motion as synovial inflammation in the acute stages of the disease progresses to capsular fibrosis in the chronic stages. Once other diagnoses have been ruled out, management of ACH is tailored to reduce inflammation in the acute stages with NSAIDs, intra-articular steroid injections, and targeted physical therapy while biomechanical dysfunction in the spine, hip, sacroiliac joint, or lower limb joints is addressed. In chronic stages of the disease, intervention should focus on decreasing the progression of fibrotic changes and regaining range of motion through aggressive physical therapy. Interventions described for chronic ACH include manipulation under anesthesia; pressure dilatation; and open or arthroscopic synovectomy, lysis of adhesions, and capsular release. Surgical intervention should be considered only after failure of a minimum 3-month course of nonsurgical treatment. PMID:24292931

  14. 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.

  15. Experimental investigation of certain internal condensing and boiling flows: Their sensitivity to pressure fluctuations and heat transfer enhancements

    NASA Astrophysics Data System (ADS)

    Kivisalu, Michael Toomas

    Space-based (satellite, scientific probe, space station, etc.) and millimeter -- to -- micro-scale (such as are used in high power electronics cooling, weapons cooling in aircraft, etc.) condensers and boilers are shear/pressure driven. They are of increasing interest to system engineers for thermal management because flow boilers and flow condensers offer both high fluid flow-rate-specific heat transfer capacity and very low thermal resistance between the fluid and the heat exchange surface, so large amounts of heat may be removed using reasonably-sized devices without the need for excessive temperature differences. However, flow stability issues and degredation of performance of shear/pressure driven condensers and boilers due to non-desireable flow morphology over large portions of their lengths have mostly prevented their use in these applications. This research is part of an ongoing investigation seeking to close the gap between science and engineering by analyzing two key innovations which could help address these problems. First, it is recommended that the condenser and boiler be operated in an innovative flow configuration which provides a non-participating core vapor stream to stabilize the annular flow regime throughout the device length, accomplished in an energy-efficient manner by means of ducted vapor re-circulation. This is demonstrated experimentally.. Second, suitable pulsations applied to the vapor entering the condenser or boiler (from the re-circulating vapor stream) greatly reduce the thermal resistance of the already effective annular flow regime. For experiments reported here, application of pulsations increased time-averaged heat-flux up to 900 % at a location within the flow condenser and up to 200 % at a location within the flow boiler, measured at the heat-exchange surface. Traditional fully condensing flows, reported here for comparison purposes, show similar heat-flux enhancements due to imposed pulsations over a range of frequencies

  16. Flutter Sensitivity to Boundary Layer Thickness, Structural Damping, and Static Pressure Differential for a Shuttle Tile Overlay Repair Concept

    NASA Technical Reports Server (NTRS)

    Scott, Robert C.; Bartels, Robert E.

    2009-01-01

    This paper examines the aeroelastic stability of an on-orbit installable Space Shuttle patch panel. CFD flutter solutions were obtained for thick and thin boundary layers at a free stream Mach number of 2.0 and several Mach numbers near sonic speed. The effect of structural damping on these flutter solutions was also examined, and the effect of structural nonlinearities associated with in-plane forces in the panel was considered on the worst case linear flutter solution. The results of the study indicated that adequate flutter margins exist for the panel at the Mach numbers examined. The addition of structural damping improved flutter margins as did the inclusion of nonlinear effects associated with a static pressure difference across the panel.

  17. Direct atmospheric pressure chemical ionisation ion trap mass spectrometry for aroma analysis: Speed, sensitivity and resolution of isobaric compounds

    NASA Astrophysics Data System (ADS)

    Jublot, Lionel; Linforth, Robert S. T.; Taylor, Andrew J.

    2005-06-01

    Atmospheric pressure chemical ionisation (APCI) sources were developed for real time analysis of volatile release from foods using an ion trap (IT) mass spectrometer (MS). Key objectives were spectral simplicity (minimal fragmentation), response time and signal to noise ratio. The benefits of APCI-IT-MS were assessed by comparing the performance for in vivo and headspace analyses with that obtained using APCI coupled to a quadrupole mass analyser. Using MS-MS, direct APCI-IT-MS was able to differentiate mixtures of some C6 and terpene isobaric aroma compounds. Resolution could be achieved for some compounds by monitoring specific secondary ions. Direct resolution was also achieved with two of the three isobaric compounds released from chocolate with time as the sample was eaten.

  18. Gait analysis in clinically healthy sheep from three different age groups using a pressure-sensitive walkway

    PubMed Central

    2012-01-01

    Background Understanding normal gait requires allowing for variations in normal patterns by the sex, age, and species in question. Therefore, the aim of this study was to evaluate kinetic and temporospatial parameters in clinically healthy sheep from three different age groups with a pressure-sensing walkway. The sheep were judged to be healthy based on the results of complete physical and orthopaedic examinations and had no history of lameness. Twenty-one clinically healthy female Santa Ines sheep were divided into three groups: G1 – seven animals, aged from 8 to 12 months and weighing 19.5-33 kg; G2 - seven individuals, aged from 2 to 4 years and weighing 26.5-42 kg; and G3 - seven sheep, aged more than 5 years and weighing 37.3-45 kg. The animals were examined from two directions: first on the left side and then on the right side of the handler. The data from the first five valid trials in each direction were collected for each sheep and analysed using the designated software. A trial was considered valid if the sheep walked within the correct velocity (1.1-1.3 m/s) and acceleration (from −0.15 to 0.15 m/s2) ranges. The peak vertical force (PVF), vertical impulse (VI), gait cycle time, stance time, swing time, stride length, and the percentage body weight distribution among the four limbs were determined. Results No significant differences were observed, in either the forelimbs or the hind limbs, between the left and right sides or between the two directions for any of the variables. No significant temporospatial differences were found among the groups. Significant PVF (%BW) differences were observed in the forelimbs (G1 > G3) and hind limbs (G1 > G3), and significant VI differences were observed in the forelimbs (G1 > G3). Conclusions Young healthy sheep differ from older sheep in the vertical forces they create when walking at the same velocity on a pressure-sensing walkway. PMID:22726641

  19. Characterization of a low-pressure chlorine plasma column sustained by propagating surface waves using phase-sensitive microwave interferometry and trace-rare-gas optical emission spectroscopy

    SciTech Connect

    Mattei, S.; Boudreault, O.; Stafford, L.; Khare, R.; Donnelly, V. M.

    2011-06-01

    Phase-sensitive microwave interferometry and trace-rare-gas optical emission spectroscopy were used to measure the line-integrated electron density, n{sub e}, and electron temperature, T{sub e}, in a high-density chlorine plasma sustained in a quartz discharge tube (inner diameter = 6 mm) by an electromagnetic surface wave at 2.45 GHz. For pressures in the 0.1-1 Torr range, n{sub e} decreased nearly linearly along the tube's z-axis down to the critical density for surface wave propagation, where the plasma decayed abruptly. At lower pressures (< 50 mTorr), however, the plasma extended well beyond this critical point, after which n{sub e} decreased quasiexponentially toward the end of the plasma column. The length of this expansion region increased with decreasing pressure, going from {approx}8 cm at 5 mTorr to {approx}1 cm at 50 mTorr. T{sub e} was nearly independent of the axial position in the main plasma region and strongly decreased in the expansion region at lower pressures. The Cl{sub 2} percent dissociation, {tau}{sub D}, obtained from the calibrated Cl{sub 2} (306 nm)-to-Xe (828 nm) emission ratio, displayed behavior similar to that of n{sub e} and T{sub e}. For example, at 5 mTorr, {tau}{sub D} was close to 100% near the wave launcher and {approx}70% at 0.5 cm from the end of the plasma column.

  20. THE STRUCTURE SENSITIVITY OF n-HEPTANE DEHYDROCYCLIZATION AND HYDROGENOLYSIS CATALYZED BY PLATINUM SINGLE CRYSTALS AT ATMOSPHERIC PRESSURE

    SciTech Connect

    Gillespie, W. D.; Herz, R. K.; Petersen, E. E.; Somorjai, G. A.

    1980-09-01

    The dehydrocyclization and hydrogenolysis of n~heptane catalyzed by platinum single crystal surfaces have been investigated at temperatures from 533 to 603 K in the range of one atmosphere total pressure, The flat (111), stepped (557), and kinked (10,8,7) and (25,10,7) surfaces used tn this study were characterized in ultrahigh vacuum by low energy electron diffraction and Auger electron spectroscopy before and after reaction experiments. The rate of dehydrocyclization to toluene on the four surfaces increased in the order (111) (25,10,7) (557) (10,8,7), Hydrogenolysis, however, increased in the order (557) (10,8,7) (111) (25,10,7), As a result, the selectivity of toluene production versus hydrogenolysis increased by an order of magnitude in the order (25,10,7) (111) (10,8,7) (557). The sum of the rates of hydrogenolysis and toluene production remains relatively constant. The effect of preoxidation of the single crystal catalysts was to increase the rate of hydrogenolysis and decrease the rate of dehydrocyclization, Iri general, the reaction rates decreased with increasing reaction time. This decrease was shown to be the result of the depositon of irreversibly adsorbed carbonaceous species.

  1. Development of a sensitive experimental set-up for LIF fuel wall film measurements in a pressure vessel

    NASA Astrophysics Data System (ADS)

    Schulz, Florian; Schmidt, Jürgen; Beyrau, Frank

    2015-05-01

    This paper focusses on fundamental investigations of fuel wall films, which are formed when the spray impinges on the piston or cylinder walls. To reproduce the wide range of operating conditions within homogeneously charged gasoline direct-injection engines, it is necessary to use a film thickness measurement method, which can be applied inside a high-pressure, high-temperature vessel. Hence, we developed a method based on laser-induced fluorescence that reaches: a precision better than 1 µm, a geometric resolution of 31 µm and a practical applicability for wall film thicknesses smaller 80 µm. To obtain accurate film thickness results, we provide a detailed description of the selection of the surrogate fuel isooctane with 3-pentanone as fluorescence tracer and the resulting assembly of the excitation source, beam expander, filters, camera and the essential image processing. Furthermore, advantages and disadvantages of other possible solutions are discussed. Earlier publications provide only little information about the accuracy of their calibration and measurement procedures. Therefore, we tested and compared three basic calibration methods to each other and provide an analysis of possible errors, such as the influence of the preferential evaporation of 3-pentanone. Finally, images of resulting wall films are presented, and practical considerations for the execution of the measurements like recording timings are discussed.

  2. Flexibilized copolyimide adhesives

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    Two copolyimides, LARC-STPI and STPI-LARC-2, with flexible backbones were processed and characterized as adhesives. The processability and adhesive properties were compared to those of a commercially available form of LARC-TPI. Lap shear specimens were fabricated using adhesive tape prepared from each of the three polymers. Lap shear tests were performed at room temperature, 177 C, and 204 C before and after exposure to water-boil and to thermal aging at 204 C for up to 1000 hours. The three adhesive systems possess exceptional lap shear strengths at room temperature and elevated temperatures both before and after thermal exposure. LARC-STPI, because of its high glass transition temperature provided high lap shear strengths up to 260 C. After water-boil, LARC-TPI exhibited the highest lap shear strengths at room temperature and 177 C, whereas the LARC-STPI retained a higher percentage of its original strength when tested at 204 C. These flexible thermoplastic copolyimides show considerable potential as adhesives based on this study and because of the ease of preparation with low cost, commercially available materials.

  3. 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

  4. Epithelial Cell Adhesion Molecule

    PubMed Central

    Trzpis, Monika; McLaughlin, Pamela M.J.; de Leij, Lou M.F.H.; Harmsen, Martin C.

    2007-01-01

    The epithelial cell adhesion molecule (EpCAM, CD326) is a glycoprotein of ∼40 kd that was originally identified as a marker for carcinoma, attributable to its high expression on rapidly proliferating tumors of epithelial origin. Normal epithelia express EpCAM at a variable but generally lower level than carcinoma cells. In early studies, EpCAM was proposed to be a cell-cell adhesion molecule. However, recent insights revealed a more versatile role for EpCAM that is not limited only to cell adhesion but includes diverse processes such as signaling, cell migration, proliferation, and differentiation. Cell surface expression of EpCAM may actually prevent cell-cell adhesion. Here, we provide a comprehensive review of the current knowledge on EpCAM biology in relation to other cell adhesion molecules. We discuss the implications of the newly identified functions of EpCAM in view of its prognostic relevance in carcinoma, inflammatory pathophysiology, and tissue development and regeneration as well as its role in normal epithelial homeostasis. PMID:17600130

  5. Blood pressure is reduced and insulin sensitivity increased in glucose-intolerant, hypertensive subjects after 15 days of consuming high-polyphenol dark chocolate.

    PubMed

    Grassi, Davide; Desideri, Giovambattista; Necozione, Stefano; Lippi, Cristina; Casale, Raffaele; Properzi, Giuliana; Blumberg, Jeffrey B; Ferri, Claudio

    2008-09-01

    Flavanols from chocolate appear to increase nitric oxide bioavailability, protect vascular endothelium, and decrease cardiovascular disease (CVD) risk factors. We sought to test the effect of flavanol-rich dark chocolate (FRDC) on endothelial function, insulin sensitivity, beta-cell function, and blood pressure (BP) in hypertensive patients with impaired glucose tolerance (IGT). After a run-in phase, 19 hypertensives with IGT (11 males, 8 females; 44.8 +/- 8.0 y) were randomized to receive isocalorically either FRDC or flavanol-free white chocolate (FFWC) at 100 g/d for 15 d. After a wash-out period, patients were switched to the other treatment. Clinical and 24-h ambulatory BP was determined by sphygmometry and oscillometry, respectively, flow-mediated dilation (FMD), oral glucose tolerance test, serum cholesterol and C-reactive protein, and plasma homocysteine were evaluated after each treatment phase. FRDC but not FFWC ingestion decreased insulin resistance (homeostasis model assessment of insulin resistance; P < 0.0001) and increased insulin sensitivity (quantitative insulin sensitivity check index, insulin sensitivity index (ISI), ISI(0); P < 0.05) and beta-cell function (corrected insulin response CIR(120); P = 0.035). Systolic (S) and diastolic (D) BP decreased (P < 0.0001) after FRDC (SBP, -3.82 +/- 2.40 mm Hg; DBP, -3.92 +/- 1.98 mm Hg; 24-h SBP, -4.52 +/- 3.94 mm Hg; 24-h DBP, -4.17 +/- 3.29 mm Hg) but not after FFWC. Further, FRDC increased FMD (P < 0.0001) and decreased total cholesterol (-6.5%; P < 0.0001), and LDL cholesterol (-7.5%; P < 0.0001). Changes in insulin sensitivity (Delta ISI - Delta FMD: r = 0.510, P = 0.001; Delta QUICKI - Delta FMD: r = 0.502, P = 0.001) and beta-cell function (Delta CIR(120) - Delta FMD: r = 0.400, P = 0.012) were directly correlated with increases in FMD and inversely correlated with decreases in BP (Delta ISI - Delta 24-h SBP: r = -0.368, P = 0.022; Delta ISI - Delta 24-h DBP r = -0.384, P = 0.017). Thus, FRDC

  6. Adhesion of elastomeric surfaces structured with micro-dimples

    NASA Astrophysics Data System (ADS)

    Nanni, Gabriele; Fragouli, Despina; Ceseracciu, Luca; Athanassiou, Athanassia

    2015-01-01

    Topography has a dominant role in determining the adhesion properties of a surface. In this work we explore how arrays of micron-sized dimples can alter the adhesion performance of elastomeric surfaces. We study the effect of the dimple surface coverage, showing that the dimples act both as passive suction devices, allowing to exceed the adhesion performance of untextured surfaces, and crack-like defects, generating stress concentration at the edge of the contact area between the surface of the sample and a flat surface. Interestingly, our results reveal that the suction effect generated by the negative pressure produced by the dimples can be effectively tuned by adjusting their depth. These findings have significant relevance for the fabrication of adhesive systems in which selective adhesion to objects with small difference in weight is required.

  7. Micromechanical adhesion force measurements between tetrahydrofuran hydrate particles.

    PubMed

    Taylor, Craig J; Dieker, Laura E; Miller, Kelly T; Koh, Carolyn A; Sloan, E Dendy

    2007-02-15

    Adhesion forces between tetrahydrofuran (THF) hydrate particles in n-decane were measured using an improved micromechanical technique. The experiments were performed at atmospheric pressure over the temperature range 261-275 K. The observed forces and trends were explained by a capillary bridge between the particles. The adhesion force of hydrates was directly proportional to the contact force and contact time. A scoping study examined the effects of temperature, anti-agglomerants, and interfacial energy on the particle adhesion forces. The adhesion force of hydrates was found to be directly proportional to interfacial energy of the surrounding liquid, and to increase with temperature. Both sorbitan monolaurate (Span20) and poly-N-vinyl caprolactam (PVCap) decreased the adhesion force between the hydrate particles. PMID:17126359

  8. Adhesive joint and composites modeling in SIERRA.

    SciTech Connect

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

    2005-11-01

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

  9. Polymer nanocomposite hydrogels exhibiting both dynamic restructuring and unusual adhesive properties.

    PubMed

    Wang, Mian; Yuan, Du; Fan, Xiaoshan; Sahoo, Nanda Gopal; He, Chaobin

    2013-06-11

    Polymer nanocomposite (NC) hydrogels exhibiting both dynamic restructuring and unusual adhesive properties in wet and dry states have been prepared in an efficient and straightforward way via free radical polymerization of poly(ethylene glycol) methyl ether acrylate (PEG) in the presence of silane-modified sodium montmorillonite (NaMMT). The dynamic restructuring of the NC gel has been demonstrated by almost instant recovery of mechanical properties, such as storage modulus, loss modulus, and damping tan δ (at 0.025 strain) by 60-110% after being stressed to the point of gel failure. Furthermore, the dry NC gel showed exceptional thermal and mechanical stability during a heating and cooling cycle between 25 and 110 °C, with only slightly decreases followed by at least 30% increases in both moduli, while tan δ remained nearly unchanged. The NC gel in dry state could repeatedly adhere to various surfaces such as steel, glass, plastic, etc., and detach from the surface without being broken and leaving little contamination behind. This unique adhesive characteristic was characterized by high storage modulus, loss modulus (kPa), and tan δ (>0.6) corresponding to high cohesive, adhesive, and tacking properties of pressure-sensitive adhesives (PSAs). Finally, a reversible network structure formed by PEO interpenetrating within 3-dimentional (3-D) silica network was proposed to be responsible for the dynamic restructuring and the unique adhesive behaviors observed in the NC gel, and the 3-D network structure was investigated by XRD, FTIR, and DSC measurements. For this 3-D network structure, we suggest that the flexibility of PEO could allow PEO side chains to contact with various surfaces by either PEO segments or methoxy end groups via weak physical interactions, such as van der Waals interactions or hydrogen bonding, whereas the reversible network structure contributes to the recovery of strength and shape after the gel failure. PMID:23721059

  10. Evolution of hardness, microstructure, and strain rate sensitivity in a Zn-22% Al eutectoid alloy processed by high-pressure torsion

    NASA Astrophysics Data System (ADS)

    Kawasaki, Megumi; Lee, Han-Joo; Choi, In-Chul; Jang, Jae-il; Ahn, Byungmin; Langdon, Terence G.

    2014-08-01

    Severe plastic deformation (SPD) is an attractive processing method for refining microstructures of metallic materials to give ultrafine grain sizes within the submicrometer to even the nanometer levels. Experiments were conducted to discuss the evolution of hardness, microstructure and strain rate sensitivity, m, in a Zn-22% Al eutectoid alloy processed by high- pressure torsion (HPT). The data from microhardness and nanoindentation hardness measurements revealed that there is a significant weakening in the Zn-Al alloy during HPT despite extensive grain refinement. Excellent room-temperature (RT) plasticity was observed in the alloy after HPT from nanoindentation creep in terms of an increased value of m. The microstructural changes with increasing numbers of HPT turns show a strong correlation with the change in the m value. Moerover, the excellent RT plasticity in the alloy is discussed in terms of the enhanced level of grain boundary sliding and the evolution of microsturucture.

  11. Protein mediated membrane adhesion

    NASA Astrophysics Data System (ADS)

    Carlson, Andreas; Mahadevan, L.

    2015-05-01

    Adhesion in the context of mechanical attachment, signaling, and movement in cellular dynamics is mediated by the kinetic interactions between membrane-embedded proteins in an aqueous environment. Here, we present a minimal theoretical framework for the dynamics of membrane adhesion that accounts for the kinetics of protein binding, the elastic deformation of the membrane, and the hydrodynamics of squeeze flow in the membrane gap. We analyze the resulting equations using scaling estimates to characterize the spatiotemporal features of the adhesive patterning and corroborate them using numerical simulations. In addition to characterizing aspects of cellular dynamics, our results might also be applicable to a range of phenomena in physical chemistry and materials science where flow, deformation, and kinetics are coupled to each other in slender geometries.

  12. Strategies to improve the adhesion of rubbers to adhesives by means of plasma surface modification

    NASA Astrophysics Data System (ADS)

    Martín-Martínez, J. M.; Romero-Sánchez, M. D.

    2006-05-01

    The surface modifications produced by treatment of a synthetic sulfur vulcanized styrene-butadiene rubber with oxidizing (oxygen, air, carbon dioxide) and non oxidizing (nitrogen, argon) RF low pressure plasmas, and by treatment with atmospheric plasma torch have been assessed by ATR-IR and XPS spectroscopy, SEM, and contact angle measurements. The effectiveness of the low pressure plasma treatment depended on the gas atmosphere used to generate the plasma. A lack of relationship between surface polarity and wettability, and peel strength values was obtained, likely due to the cohesive failure in the rubber obtained in the adhesive joints. In general, acceptable adhesion values of plasma treated rubber were obtained for all plasmas, except for nitrogen plasma treatment during 15 minutes due to the creation of low molecular weight moieties on the outermost rubber layer. A toluene wiping of the N{2 } plasma treated rubber surface for 15 min removed those moieties and increased adhesion was obtained. On the other hand, the treatment of the rubber with atmospheric pressure by means of a plasma torch was proposed. The wettability of the rubber was improved by decreasing the rubber-plasma torch distance and by increasing the duration because a partial removal of paraffin wax from the rubber surface was produced. The rubber surface was oxidized by the plasma torch treatment, and the longer the duration of the plasma torch treatment, the higher the degree of surface oxidation (mainly creation of C O moieties). However, although the rubber surface was effectively modified by the plasma torch treatment, the adhesion was not greatly improved, due to the migration of paraffin wax to the treated rubber-polyurethane adhesive interface once the adhesive joint was produced. On the other hand, the extended treatment with plasma torch facilitated the migration of zinc stearate to the rubber-adhesive interface, also contributing to deteriorate the adhesion in greater extent. Finally

  13. 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

  14. How Does Circadian Rhythm Impact Salt Sensitivity of Blood Pressure in Mice? A Study in Two Close C57Bl/6 Substrains

    PubMed Central

    Combe, Roy; Mudgett, John; El Fertak, Lahcen; Champy, Marie-france; Ayme-Dietrich, Estelle; Petit-Demoulière, Benoit; Sorg, Tania; Herault, Yann; Madwed, Jeffrey B.; Monassier, Laurent

    2016-01-01

    Background Mouse transgenesis has provided the unique opportunity to investigate mechanisms underlying sodium kidney reabsorption as well as end organ damage. However, understanding mouse background and the experimental conditions effects on phenotypic readouts of engineered mouse lines such as blood pressure presents a challenge. Despite the ability to generate high sodium and chloride plasma levels during high-salt diet, observed changes in blood pressure are not consistent between wild-type background strains and studies. Methods The present work was designed in an attempt to determine guidelines in the field of salt-induced hypertension by recording continuously blood pressure by telemetry in mice submitted to different sodium and potassium loaded diets and changing experimental conditions in both C57BL/6N and C57BL/6J mice strain (Normal salt vs. Low salt vs. High-salt/normal potassium vs. High salt/low potassium, standard vs. modified light cycle, Non-invasive tail cuff blood pressure vs. telemetry). Results In this study, we have shown that, despite a strong blood pressure (BP) basal difference between C57BL/6N and C57BL/6J mice, High salt/normal potassium diet increases BP and heart rate during the active phase only (dark period) in the same extent in both strains. On the other hand, while potassium level has no effect on salt-induced hypertension in C57BL/6N mice, high-salt/low potassium diet amplifies the effect of the high-salt challenge only in C57BL/6J mice. Indeed, in this condition, salt-induced hypertension can also be detected during light period even though this BP increase is lower compared to the one occurring during the dark period. Finally, from a methodological perspective, light cycle inversion has no effect on this circadian BP phenotype and tail-cuff method is less sensitive than telemetry to detect BP phenotypes due to salt challenges. Conclusions Therefore, to carry investigations on salt-induced hypertension in mice, chronic telemetry

  15. 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.

  16. 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.

  17. Timer cover adhesive optimization

    SciTech Connect

    Carleton, J.J. II.

    1992-03-17

    The implementation of PROCODE as the data acquisition system for processing timers has required some modifications to the method of identifying timer assemblies. PROCODE requires machine-readable labelling of the assemblies. This report describes a series of experiments to find an adhesive that would keep labels attached to timers regardless of the condition of their surface when the label was applied and regardless of the heat, vibration, and shock they endured afterwards. The effect of the variation of these experimental factors on the performance of the adhesive was determined by using a Taguchi experimental design.

  18. Evidence for singlet oxygen generation and biocidal activity in photo-responsive metallic nitride fullerene – polymer adhesive films

    PubMed Central

    McCluskey, D. Michelle; Smith, Tiffany N.; Madasu, Praveen K.; Coumbe, Curtis E.; Mackey, Mary A.; Fulmer, Preston A.; Wynne, James H.; Stevenson, Steven; Phillips, J. Paige

    2009-01-01

    The adhesive properties, as measured by bulk tack analysis, are found to decrease in blends of isomerically pure Sc3N@Ih-C80 metallic nitride fullerene (MNF) and polystyrene-block-polyisoprene-block-polystyrene (SIS) copolymer pressure sensitive adhesive (PSA) under white light irradiation in air. Reduction of tack is attributed to the in-situ generation of 1O2 and subsequent photooxidative crosslinking of the adhesive film. Comparisons are drawn to classical fullerenes C60 and C70 for this process. This work represents the first demonstration of 1O2 generating ability in the general class of metallic nitride fullerenes, (M3N@C80). Additional support is provided for the sensitizing ability of Sc3N@Ih-C80 through the successful photooxygenation of 2-methyl-2-butene to its allylic hydroperoxides in benzene-d6 under irradiation at 420 nm, a process which occurs at a comparable rate to C60. Photooxygenation of 2-methyl-2-butene is found to be influenced by the fullerene sensitizer concentration and oxygen gas flow rate. Molar extinction coefficients are reported for Sc3N@Ih-C80 at 420 nm and 536 nm. Evaluation of the potential antimicrobial activity of films prepared in this study stemming from the in-situ generation of 1O2 led to an observed 1 log kill for select Gram-positive and Gram-negative bacteria. PMID:20161355

  19. Evidence for singlet-oxygen generation and biocidal activity in photoresponsive metallic nitride fullerene-polymer adhesive films.

    PubMed

    McCluskey, D Michelle; Smith, Tiffany N; Madasu, Praveen K; Coumbe, Curtis E; Mackey, Mary A; Fulmer, Preston A; Wynne, James H; Stevenson, Steven; Phillips, J Paige

    2009-04-01

    The adhesive properties, as measured by bulk tack analysis, are found to decrease in blends of isomerically pure Sc3N@I(h)-C80 metallic nitride fullerene (MNF) and polystyrene-block-polyisoprene-block-polystyrene (SIS) copolymer pressure-sensitive adhesive under white light irradiation in air. The reduction of tack is attributed to the in situ generation of 1O2 and subsequent photooxidative cross-linking of the adhesive film. Comparisons are drawn to classical fullerenes C60 and C70 for this process. This work represents the first demonstration of 1O2 generating ability in the general class of MNFs (M3N@C80). Additional support is provided for the sensitizing ability of Sc3N@I(h)-C80 through the successful photooxygenation of 2-methyl-2-butene to its allylic hydroperoxides in benzene-d(6) under irradiation at 420 nm, a process that occurs at a rate comparable to that of C(60). Photooxygenation of 2-methyl-2-butene is found to be influenced by the fullerene sensitizer concentration and O2 flow rate. Molar extinction coefficients are reported for Sc3N@I(h)-C80 at 420 and 536 nm. Evaluation of the potential antimicrobial activity of films prepared in this study stemming from the in situ generation of 1O2 led to an observed 1 log kill for select Gram-positive and Gram-negative bacteria. PMID:20161355

  20. High Strain-Rate Compressive Behavior of Bulk Structural Adhesives: Epoxy and Methacrylate Adhesives

    NASA Astrophysics Data System (ADS)

    Yokoyama, Takashi; Nakai, Kenji; Yatim, Norfazrina Hayati Mohd

    The present paper describes the determination of high strain-rate compressive stress-strain loops for bulk specimens of two different epoxy and methacrylate structural adhesives on the standard split Hopkinson pressure bar with a tapered striker bar. The full compressive stress-strain data including unloading process are obtained over a wide range of strain rates from 10-3 to 103/s at room temperature. The effects of strain rate on the initial (secant) modulus, flow stress, dissipation energy and hysteresis loss ratio are studied. The experimental results show that both bulk structural adhesives exhibit highly strain-rate dependent viscoelastic behavior like polymeric materials.

  1. Impact of a Culturally Sensitive Health Self-Empowerment Workshop Series on Health Behaviors/Lifestyles, BMI, and Blood Pressure of Culturally Diverse Overweight/Obese Adults

    PubMed Central

    Tucker, Carolyn M.; Butler, Ashley; Kaye, Lillian B.; Nolan, Sarah E. M.; Flenar, Delphia J.; Marsiske, Michael; Bragg, Marie; Hoover, Eddie; Daly, Katherine

    2013-01-01

    Objective Examine the impact of the Health Self-Empowerment Theory-based, culturally sensitive Health Self-Empowerment (HSE) Workshop Series to Modify and Prevent Obesity on levels of health promoting (health-smart) behaviors, motivators of and barriers to these behaviors, health promoting lifestyle variables, and health status indicators (Body Mass Index [BMI] and blood pressure) among a culturally diverse sample of overweight/obese adults from mostly low income households. Design 153 overweight/obese adults participated in an Immediate Treatment (IT) Group (n = 100) or a Waitlist Control (WC) Group (n = 53). Results Post-intervention, the IT Group compared to the WC Group reported (a) significantly higher engagement in physical activity and healthy eating, (b) significantly less intake of calories, total fat, transfat, saturated fat, sugar, and added sugar, (c) significantly higher motivators for engaging in two of four specific health-smart behaviors, (d) significantly lower barriers to engaging in three of four specific health-smart behaviors, and (e) significantly lower BMI and systolic blood pressure. Conclusion The HSE Workshop Series may be an effective intervention for treating and preventing obesity among diverse low-income adults – individuals who often perceive/experience limited power over their health. Health care providers, particularly physicians, have important health empowerment roles in this intervention. PMID:24910589

  2. Intermittent electrical stimulation of the right cervical vagus nerve in salt-sensitive hypertensive rats: effects on blood pressure, arrhythmias, and ventricular electrophysiology

    PubMed Central

    Annoni, Elizabeth M; Xie, Xueyi; Lee, Steven W; Libbus, Imad; KenKnight, Bruce H; Osborn, John W; Tolkacheva, Elena G

    2015-01-01

    Hypertension (HTN) is the single greatest risk factor for potentially fatal cardiovascular diseases. One cause of HTN is inappropriately increased sympathetic nervous system activity, suggesting that restoring the autonomic nervous balance may be an effective means of HTN treatment. Here, we studied the potential of vagus nerve stimulation (VNS) to treat chronic HTN and cardiac arrhythmias through stimulation of the right cervical vagus nerve in hypertensive rats. Dahl salt-sensitive rats (n = 12) were given a high salt diet to induce HTN. After 6 weeks, rats were randomized into two groups: HTN-Sham and HTN-VNS, in which VNS was provided to HTN-VNS group for 4 weeks. In vivo blood pressure and electrocardiogram activities were monitored continuously by an implantable telemetry system. After 10 weeks, rats were euthanized and their hearts were extracted for ex vivo electrophysiological studies using high-resolution optical mapping. Six weeks of high salt diet significantly increased both mean arterial pressure (MAP) and pulse pressure, demonstrating successful induction of HTN in all rats. After 4 weeks of VNS treatment, the increase in MAP and the number of arrhythmia episodes in HTN-VNS rats was significantly attenuated when compared to those observed in HTN-Sham rats. VNS treatment also induced changes in electrophysiological properties of the heart, such as reduction in action potential duration (APD) during rapid drive pacing, slope of APD restitution, spatial dispersion of APD, and increase in conduction velocity of impulse propagation. Overall, these results provide further evidence for the therapeutic efficacy of VNS in HTN and HTN-related heart diseases. PMID:26265746

  3. Switchable bio-inspired adhesives

    NASA Astrophysics Data System (ADS)

    Kroner, Elmar

    2015-03-01

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

  4. Exercise transcutaneous oxygen pressure measurement has good sensitivity and specificity to detect lower extremity arterial stenosis assessed by computed tomography angiography.

    PubMed

    Koch, Caroline; Chauve, Emmanuel; Chaudru, Ségolène; Le Faucheur, Alexis; Jaquinandi, Vincent; Mahé, Guillaume

    2016-09-01

    Peripheral artery disease (PAD) is a highly prevalent disease diagnosed by the use of ankle-brachial index (ABI) at rest. In some clinical conditions (diabetes, renal insufficiency, advanced age), ABI can be falsely normal and other tests are required for the PAD diagnosis (American Heart Association statement). This study was conducted to determine the accuracy of exercise transcutaneous oxygen pressure measurement (exercise-TcPo2) in detection of arterial stenosis ≥50% using computed tomography angiography (CTA) as the gold standard.We retrospectively analyzed consecutive patients referred to our vascular unit (University Hospital, Rennes, France) for exercise-TcPo2 testing from 2014 to 2015. All included patients had a CTA performed within 3 months of the exercise-TcPo2 test. Exercise-TcPo2 was performed on treadmill (10% slope; 2 mph speed). We calculated the Delta from Resting Oxygen Pressure (DROP) index (expressed in mm Hg) at the proximal and distal levels. Two blinded physicians performed stenosis quantification on CTA. The receiver operating characteristic (ROC) curve was used to define a cutoff point to detect arterial stenosis ≥50%, stenosis ≥60%, and stenosis ≥70%.A total of 34 patients (mean age 64 ± 2 years old; 74% men) were analyzed. The highest areas under the curve (AUC) were found for 60% stenosis at both proximal and distal levels. For stenosis ≥50%, sensitivity and specificity of proximal minimal DROP were 80.9% [67.1-89.7], 81.0% [59.3-92.7] respectively. For stenosis ≥50%, sensitivity and specificity of distal minimal DROP were 73.2% [60.3-83.1], 83.3% [53.8-96.2], respectively. For stenosis ≥60%, sensitivity and specificity of proximal minimal DROP were 82.5% [67.6-91.5] and 85.7% [67.7-94.8] respectively. For stenosis ≥60%, sensitivity and specificity of distal minimal DROP were 80.4% [67.3-89.1] and 88.2% [64.2-97.7], respectively. For stenosis ≥70%, sensitivity and specificity of proximal minimal DROP were 85

  5. Monkey pulpal responses to conventional and adhesive luting cements.

    PubMed

    Inokoshi, S; Fujitani, M; Otsuki, M; Sonoda, H; Kitasako, Y; Shimada, Y; Tagami, J

    1998-01-01

    Monkey pulpal responses to metal inlays luted with a combination of an adhesive resin and luting composite and conventional dental cements were histopathologically evaluated. Initial pulpal responses caused by re-exposure of the cut dentin surfaces and luting procedure under hydraulic pressure subsided at 90 days after final cementation. There was no significant difference among pulpal reactions to conventional dental cements and a combination of an adhesive resin and luting composite. The adhesive resin coating of freshly cut dentinal walls/floors immediately after cavity preparation seems to provide protection for the dentin and pulp in indirect restorations requiring temporary sealing. PMID:9610329

  6. Role of seta angle and flexibility in the gecko adhesion mechanism

    NASA Astrophysics Data System (ADS)

    Hu, Congcong; Alex Greaney, P.

    2014-08-01

    A model is developed to describe the reversible nature of gecko dry adhesion. The central aspect of this model is that the seta can be easily peeled away from the contacting surface by a small moment at the contact tip. It is shown that this contact condition is very sensitive, but can result in robust adhesion if individual setae are canted and highly flexible. In analogy to the "cone of friction," we consider the "adhesion region"—the domain of normal and tangential forces that maintain adhesion. Results demonstrate that this adhesion region is highly asymmetric enabling the gecko to adhere under a variety of loading conditions associated with scuttling horizontally, vertically, and inverted. Moreover, under each of these conditions, there is a low energy path to de-adhesion. In this model, obliquely canted seta (as possessed by geckos) rather than vertically aligned fibers (common in synthetic dry adhesive) provides the most robust adhesion.

  7. 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.

  8. Adept Adhesion Reduction Solution

    MedlinePlus

    ... icodextrin. The fluid is used during or after laparoscopic gynecological surgery to separate and protect tissues and decrease the number of new adhesions after surgery. Adept® is supplied sterile, in a single-use bag. How does it work? During surgery, ...

  9. Adhesion molecules and receptors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adhesion molecules are necessary for leukocyte trafficking and differentiation. They serve to initiate cell-cell interactions under conditions of shear, and they sustain the cell-cell and cell-matrix interactions needed for cellular locomotion. They also can serve directly as signaling molecules act...

  10. 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.

  11. Resistance heating releases structural adhesive

    NASA Technical Reports Server (NTRS)

    Glemser, N. N.

    1967-01-01

    Composite adhesive package bonds components together for testing and enables separation when testing is completed. The composite of adhesives, insulation and a heating element separate easily when an electrical current is applied.

  12. Adhesion testing of aircraft tires

    NASA Technical Reports Server (NTRS)

    Bobo, S. N.

    1983-01-01

    Adhesion testing appeared to offer a less burdensome alternative to replace some of the dynamometer tests. Accordingly, test results and data were requested from retreaders who had used adhesion testing.

  13. 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.

  14. Deformations and strains in adhesive joints by moire interferometry

    NASA Technical Reports Server (NTRS)

    Post, D.; Czarnek, R.; Wood, J.; John, D.; Lubowinski, S.

    1984-01-01

    Displacement fields in a thick adherend lap joint and a cracked lap shear specimen were measured by high sensitivity moire interferometry. Contour maps of in-plane U and V displacements were obtained across adhesive and adherent surfaces. Loading sequences ranged from modest loads to near-failure loads. Quantitative results are given for displacements and certain strains in the adhesive and along the adhesive/adherend boundary lines. The results show nonlinear displacements and strains as a function of loads or stresses and they show viscoelastic or time-dependent response. Moire interferometry is an excellent method for experimental studies of adhesive joint performance. Subwavelength displacement resolution of a few micro-inches, and spatial resolution corresponding to 1600 fringes/inch (64 fringes/mm), were obtained in these studies. The whole-field contour maps offer insights not available from local measurements made by high sensitivity gages.

  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. Spectroscopic and morphologic characterization of the dentin/adhesive interface

    NASA Astrophysics Data System (ADS)

    Lemor, R. M.; Kruger, Michael B.; Wieliczka, David M.; Swafford, Jim R.; Spencer, Paulette

    1999-01-01

    The potential environmental risks associated with mercury release have forced many European countries to ban the use of dental amalgam. Alternative materials such as composite resins do not provide the clinical function for the length of time characteristically associated with dental amalgam. The weak link in the composite restoration is the dentin/adhesive bond. The purpose of this study was to correlate morphologic characterization of the dentin/adhesive bond with chemical analyses using micro- Fourier transform infrared and micro-Raman spectroscopy. A commercial dental adhesive was placed on dentin substrates cut from extracted, unerupted human third molars. Sections of the dentin/adhesive interface were investigated using infrared radiation produced at the Aladdin synchrotron source; visible radiation from a Kr+ laser was used for the micro-Raman spectroscopy. Sections of the dentin/adhesive interface, differentially stained to identify protein, mineral, and adhesive, were examined using light microscopy. Due to its limited spatial resolution and the unknown sample thickness the infrared results cannot be used quantitatively in determining the extent of diffusion. The results from the micro-Raman spectroscopy and light microscopy indicate exposed protein at the dentin/adhesive interface. Using a laser that reduces background fluorescence, the micro-Raman spectroscopy provides quantitative chemical and morphologic information on the dentin/adhesive interface. The staining procedure is sensitive to sites of pure protein and thus, complements the Raman results.

  17. Adhesion of hydrogels under water by hydrogen bonding: from molecular interactions to macroscopic adhesion

    NASA Astrophysics Data System (ADS)

    Creton, Costantino

    2012-02-01

    Hydrogels are an essential part of living organisms and are widely used in biotechnologies, health care and food science. Although swelling properties, cell adhesion on gel surfaces and gel elasticity have attracted much interest, macroscopic adhesion of hydrogels on solid surfaces in aqueous environment is much less well understood. We studied systematically and in aqueous environment, the reversible adhesion by hydrogen bonding of macroscopic model hydrogels of polydimethylacrylamide (PDMA) or of polyacrylamide (PAAm) on solid surfaces functionalized with polyacrylic acid (PAA) polymer brushes. The hydrogels were synthesized by free radical polymerization and the brushes were prepared by grafting polytertbutyl acrylate chains and converting them by pyrolisis into polyacrylic acid. A new adhesion tester based on the flat punch geometry was designed and used to control the contact area, contact time, contact pressure and debonding velocity of the gels from the surface while the samples were fully immersed in water. The adhesion tests were performed at different pH and temperatures and the modulus of the gel and grafting density and molecular weight of the brushes was varied. Macroscopic adhesion results were compared with phase diagrams in dilute solution to detect molecular interactions. While the PDMA/PAA pair behaved very similarly in solution and in macroscopic adhesion tests, the PAAm/PAA pair showed an unexpectedly high adhesion level relatively to its complexation ability in dilute solution. Surprisingly, time dependent experiments showed that the kinetics of H-bond formation and breakup at interfaces was very slow resulting in adhesion energies which were very dependent on contact time up to one hour of contact. At the molecular level, neutron reflectivity showed that the equilibrium brush conformation when in contact with the gels was more extended at pH2 (H-bonds activated) than at pH9 (H-bonds deactivated) and that a certain applied pressure was

  18. Inertial and stick-slip regimes of unstable adhesive tape peeling.

    PubMed

    Dalbe, Marie-Julie; Villey, Richard; Ciccotti, Matteo; Santucci, Stéphane; Cortet, Pierre-Philippe; Vanel, Loïc

    2016-05-18

    We present an experimental characterization of the detachment front unstable dynamics observed during the peeling of pressure sensitive adhesives. We use an experimental set-up specifically designed to control the peeling angle θ and the peeled tape length L, while peeling an adhesive tape from a flat substrate at a constant driving velocity V. High-speed imaging allows us to report the evolution of the period and amplitude of the front oscillations, as well as the relative durations of their fast and slow phases, as a function of the control parameters V, L and θ. Our study shows that, as the driving velocity or the peeling angle increases, the oscillations of the peeling front progressively evolve from genuine "stick-slip" oscillations, made of alternating long stick phases and very brief slip phases, to sinusoidal oscillations of amplitude twice the peeling velocity. We propose a model which, taking into account the peeling angle-dependent kinetic energy cost to accelerate and decelerate the peeled tape, explains the transition from the "stick-slip" to the "inertial" regime of the dynamical instability. Using independent direct measurements of the effective fracture energy of the adhesive-substrate joint, we show that our model quantitatively accounts for the two regimes of the unstable dynamics. PMID:27050487

  19. Physics of cell elasticity, shape and adhesion

    NASA Astrophysics Data System (ADS)

    Safran, S. A.; Gov, N.; Nicolas, A.; Schwarz, U. S.; Tlusty, T.

    2005-07-01

    We review recent theoretical work that analyzes experimental measurements of the shape, fluctuations and adhesion properties of biological cells. Particular emphasis is placed on the role of the cytoskeleton and cell elasticity and we contrast the shape and adhesion of elastic cells with fluid-filled vesicles. In red blood cells (RBC), the cytoskeleton consists of a two-dimensional network of spectrin proteins. Our analysis of the wavevector and frequency dependence of the fluctuation spectrum of RBC indicates that the spectrin network acts as a confining potential that reduces the fluctuations of the lipid bilayer membrane. However, since the cytoskeleton is only sparsely connected to the bilayer, one cannot regard the composite cytoskeleton-membrane as a polymerized object with a shear modulus. The sensitivity of RBC fluctuations and shapes to ATP concentration may reflect topological defects induced in the cytoskeleton network by ATP. The shapes of cells that adhere to a substrate are strongly determined by the cytoskeletal elasticity that can be varied experimentally by drugs that depolymerize the cytoskeleton. This leads to a tension-driven retraction of the cell body and a pearling instability of the resulting ray-like protrusions. Recent experiments have shown that adhering cells exert polarized forces on substrates. The interactions of such “force dipoles” in either bulk gels or on surfaces can be used to predict the nature of self-assembly of cell aggregates and may be important in the formation of artificial tissues. Finally, we note that cell adhesion strongly depends on the forces exerted on the adhesion sites by the tension of the cytoskeleton. The size and shape of the adhesion regions are strongly modified as the tension is varied and we present an elastic model that relates this tension to deformations that induce the recruitment of new molecules to the adhesion region. In all these examples, cell shape and adhesion differ from vesicle shape and

  20. Elastic Light Tunable Tissue Adhesive Dendrimers.

    PubMed

    Feng, Gao; Djordjevic, Ivan; Mogal, Vishal; O'Rorke, Richard; Pokholenko, Oleksandr; Steele, Terry W J

    2016-07-01

    Development of bioadhesive formulations for tissue fixation remains a challenge. The major drawbacks of available bioadhesives are low adhesion strength, toxic byproducts, and complexity of application onto affected tissues. In order to address these problems, this study has developed a hydrogel bioadhesive system based on poly amido amine (PAMAM) dendrimer, grafted (conjugated) with UV-sensitive, 4-[3-(trifluoromethyl)-3H-diazirin-3-yl] benzyl bromide (PAMAM-g-diazirine). This particular diazirine molecule can be grafted to the surface amine groups of PAMAM in a one-pot synthesis. Diazirine functionalities are carbene precursors that form covalent crosslinks with hydrated tissues after low-power UV activation without necessity of free-radical initiators. The rheological properties and adhesion strength to ex vivo tissues are highly controllable depending on diazirine grafting, hydrogel concentration, and UV dose intensity fitting variety types of tissues. Covalent bonds at the tissue/bioadhesive interface provide robust adhesive and mechanical strength in a highly hydrated environment. The free flowing hydrogel conversion to elastic adhesive after UV activation allows intimate contact with the ex vivo swine tissue surfaces with low in vitro cytotoxicity observed, making it a promising bioadhesive formulation toward clinical applications. PMID:27061355