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, 2011 CFR

    2011-04-01

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

  5. 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...

  6. New pressure-sensitive silicone adhesive

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  7. 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

  8. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false 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....

  9. Development of Screenable Pressure Sensitive Adhesives

    SciTech Connect

    Steven J. Severtson

    2003-11-29

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

  10. Controlled release in transdermal pressure sensitive adhesives using organosilicate nanocomposites.

    PubMed

    Shaikh, Sohel; Birdi, Anil; Qutubuddin, Syed; Lakatosh, Eric; Baskaran, Harihara

    2007-12-01

    Polydimethyl siloxane (PDMS) based pressure sensitive adhesives (PSA) incorporating organo-clays at different loadings were fabricated via solution casting. Partially exfoliated nanocomposites were obtained for the hydroxyl terminated PDMS in ethyl acetate solvent as determined by X-ray diffraction and atomic force microscopy. Drug release studies showed that the initial burst release was substantially reduced and the drug release could be controlled by the addition of organo-clay. Shear strength and shear adhesion failure temperature (SAFT) measurements indicated substantial improvement in adhesive properties of the PSA nanocomposite adhesives. Shear strength showed more than 200% improvement at the lower clay loadings and the SAFT increased by about 21% due to the reinforcement provided by the nano-dispersed clay platelets. It was found that by optimizing the level of the organosilicate additive to the polymer matrix, superior control over drug release kinetics and simultaneous improvements in adhesive properties could be attained for a transdermal PSA formulation. PMID:17786555

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... levels not to exceed 1.0 percent by weight of the adhesive formulation. Chlorinated natural rubber.... Rubber hydrochloride. Rubber (natural latex solids or crepe, smoked or unsmoked). Terpene resins (α- and.... Butyl rubber. Butylated reaction product of p-cresol and dicyclopentadiene produced by reacting...

  17. Role of pressure-sensitive adhesives in transdermal drug delivery systems.

    PubMed

    Lobo, Shabbir; Sachdeva, Sameer; Goswami, Tarun

    2016-01-01

    Transdermal drug delivery systems (TDDS) are employed for the delivery of drugs across skin into the systemic circulation. Pressure-sensitive adhesive (PSA) is one of the most critical components used in a TDDS. The primary function of PSA is to help in adhesion of patch to skin, but more importantly it acts as a matrix for the drug and other excipients. Hence, apart from adhesion of the patch, PSA also affects other critical quality attributes of the TDDS such as drug delivery, flux through skin and physical and chemical stability of the finished product. This review article provides a summary of the adhesives used in various types of TDDS. In particular, this review will cover the design types of TDDS, categories of PSAs and their evaluation and regulatory aspects.

  18. Rate and Temperature Dependence of Adhesion Measured by a Jkr Method on Synthetically Modified Acrylic Pressure Sensitive Adhesives

    NASA Astrophysics Data System (ADS)

    Garif, Yev; Gerberich, William; Macosko, Christopher; Pocius, Alphonsus

    2003-03-01

    The goal of this study is to model mechanisms of interfacial separation in soft polymers based on experimental results obtained from normal mechanical contacts (JKR test). For the JKR test, cylindrically shaped samples of acrylic pressure sensitive adhesives (PSAs) were synthesized in capillary tubes in presence of a cross-linking agent in order to obtain an elastic PSA-like network (PSA-LN). Surface characteristics of individual samples were altered by co-polymerizing small amounts of polar side-groups such as acrylic acid (AA), dimethylaminoethylacrylate (DMAEA), and acrylonitrile (AN). The measurement was conducted in a ventilated chamber at three different temperatures (0, 25, and 50 degrees Celcius) and zero humidity with a sub-micron-per-second range of contact rates. Within this range, measured adhesion exhibits a transition from nearly rate-independent behavior to power law behavior at higher rates. Power law index matches that from the peel test data of similarly synthesized adhesive tapes. Accordingly, the transition is linked to the characteristic length scale of the process zone at the interface, as opposed to the bulk, ahead of the slowly advancing crack tip.

  19. 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.

  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. 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.

  2. 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

  3. 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.

  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. Dietary carbohydrate restriction improves insulin sensitivity, blood pressure, microvascular function, and cellular adhesion markers in individuals taking statins.

    PubMed

    Ballard, Kevin D; Quann, Erin E; Kupchak, Brian R; Volk, Brittanie M; Kawiecki, Diana M; Fernandez, Maria Luz; Seip, Richard L; Maresh, Carl M; Kraemer, William J; Volek, Jeff S

    2013-11-01

    Statins positively impact plasma low-density lipoprotein cholesterol, inflammation and vascular endothelial function (VEF). Carbohydrate restricted diets (CRD) improve atherogenic dyslipidemia, and similar to statins, have been shown to favorably affect markers of inflammation and VEF. No studies have examined whether a CRD provides additional benefit beyond that achieved by habitual statin use. We hypothesized that a CRD (<50 g carbohydrate/d) for 6 weeks would improve lipid profiles and insulin sensitivity, reduce blood pressure, decrease cellular adhesion and inflammatory biomarkers, and augment VEF (flow-mediated dilation and forearm blood flow) in statin users. Participants (n = 21; 59.3 ± 9.3 y, 29.5 ± 3.0 kg/m(2)) decreased total caloric intake by approximately 415 kcal at 6 weeks (P < .001). Daily nutrient intakes at baseline (46/36/17% carb/fat/pro) and averaged across the intervention (11/58/28% carb/fat/pro) demonstrated dietary compliance, with carbohydrate intake at baseline nearly 5-fold greater than during the intervention (P < .001). Compared to baseline, both systolic and diastolic blood pressure decreased after 3 and 6 weeks (P < .01). Peak forearm blood flow, but not flow-mediated dilation, increased at week 6 compared to baseline and week 3 (P ≤ .03). Serum triglyceride, insulin, soluble E-Selectin and intracellular adhesion molecule-1 decreased (P < .01) from baseline at week 3, and this effect was maintained at week 6. In conclusion, these findings demonstrate that individuals undergoing statin therapy experience additional improvements in metabolic and vascular health from a 6 weeks CRD as evidenced by increased insulin sensitivity and resistance vessel endothelial function, and decreased blood pressure, triglycerides, and adhesion molecules. PMID:24176230

  6. Dietary carbohydrate restriction improves insulin sensitivity, blood pressure, microvascular function, and cellular adhesion markers in individuals taking statins.

    PubMed

    Ballard, Kevin D; Quann, Erin E; Kupchak, Brian R; Volk, Brittanie M; Kawiecki, Diana M; Fernandez, Maria Luz; Seip, Richard L; Maresh, Carl M; Kraemer, William J; Volek, Jeff S

    2013-11-01

    Statins positively impact plasma low-density lipoprotein cholesterol, inflammation and vascular endothelial function (VEF). Carbohydrate restricted diets (CRD) improve atherogenic dyslipidemia, and similar to statins, have been shown to favorably affect markers of inflammation and VEF. No studies have examined whether a CRD provides additional benefit beyond that achieved by habitual statin use. We hypothesized that a CRD (<50 g carbohydrate/d) for 6 weeks would improve lipid profiles and insulin sensitivity, reduce blood pressure, decrease cellular adhesion and inflammatory biomarkers, and augment VEF (flow-mediated dilation and forearm blood flow) in statin users. Participants (n = 21; 59.3 ± 9.3 y, 29.5 ± 3.0 kg/m(2)) decreased total caloric intake by approximately 415 kcal at 6 weeks (P < .001). Daily nutrient intakes at baseline (46/36/17% carb/fat/pro) and averaged across the intervention (11/58/28% carb/fat/pro) demonstrated dietary compliance, with carbohydrate intake at baseline nearly 5-fold greater than during the intervention (P < .001). Compared to baseline, both systolic and diastolic blood pressure decreased after 3 and 6 weeks (P < .01). Peak forearm blood flow, but not flow-mediated dilation, increased at week 6 compared to baseline and week 3 (P ≤ .03). Serum triglyceride, insulin, soluble E-Selectin and intracellular adhesion molecule-1 decreased (P < .01) from baseline at week 3, and this effect was maintained at week 6. In conclusion, these findings demonstrate that individuals undergoing statin therapy experience additional improvements in metabolic and vascular health from a 6 weeks CRD as evidenced by increased insulin sensitivity and resistance vessel endothelial function, and decreased blood pressure, triglycerides, and adhesion molecules.

  7. 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.

  8. 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).

  9. Characterizing acrylic pressure-sensitive adhesive tapes favoring diverse biomedical applications

    NASA Astrophysics Data System (ADS)

    Alhijji, Saleh Mohammed S.

    Strong, self-adhesive acrylic polymer-based tapes have been identified as FDA-approved medical device construction components that might also serve in diverse biological locations as artificial muscles, ligaments, or compressive support discs. After assuring that the tapes themselves were not cytotoxic, they were evaluated as possible low-tension muscle substitutes for eyelids, jaws, and other modest body re-closing needs, and well as for higher-tension applications as artificial ligaments. Self-adhesion of the tapes to representative biomaterials, before and after radio-frequency glow discharge treatment for surface energy modification, illustrated the conditions for maximum attachment strength to nonphysiologic substances. Attachment to bony host parts was challenging but apparently met by the application of acrylic-composite-to-dentin bonding systems that has shown good long-term experience in the mouth. Above all, the compression-relaxation properties of the tape materials were superior and their uses in potential Nucleus Pulposus applications for spinal disc repair were most completely explored. Tests included tape-disc performance longevity, both dry and wet, for over 5000 load-relaxation cycles, with no apparent changes in results for the most dense of the tapes evaluated. Direct abrasion was avoided by insertion of rigid polymeric layers. It is recommended that the compressive loading properties of acrylic tapes be further evaluated for spine repair applications.

  10. 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.

  11. 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

  12. Drug in adhesive patch of palonosetron: Effect of pressure sensitive adhesive on drug skin permeation and in vitro-in vivo correlation.

    PubMed

    Liu, Chao; Hui, Mei; Quan, Peng; Fang, Liang

    2016-09-25

    Palonosetron (PAL) is recommended for the prevention of chemotherapy-induced nausea and vomiting. The aim of this study was to develop a long-acting PAL transdermal patch to improve patient compliance. We were particularly concerned about the effect of pressure sensitive adhesives (PSAs) on PAL skin permeability. Formulation factors including PSAs, backing films and drug loadings were investigated in the in vitro skin permeation study using rabbit skin. Fourier transform infrared spectrometer study and thermal analysis were conducted to investigate the drug-PSA interaction and thermodynamic activity of PSAs, respectively. The results indicated that high drug skin permeation amount was obtained in PSA DURO-TAK(®)87-2516, which had low interaction potential with PAL and high thermodynamic activity. The optimized patch was composed of PAL of 8 %, DURO-TAK(®)87-2516 as PSA, CoTran™ 9700 as backing film and Scotchpak™ 9744 as release liner. The in vitro skin permeation amount of the optimized patch was 734.0±55.8μg/cm(2) during 3-day administration. The absolute bioavailability of the optimized patch was 43 % in rabbit and a good in vitro-in vivo correlation coefficient was obtained (R(2)=0.989). These results indicated the feasibility of PAL transdermal patch in the prevention of chemotherapy-induced nausea and vomiting. PMID:27521703

  13. 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.

  14. 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

  15. SENSITIVE PRESSURE GAUGE

    DOEpatents

    Ball, W.P.

    1961-01-01

    An electron multiplier device is described. It has a plurality of dynodes between an anode and cathode arranged to measure pressure, temperature, or other environmental physical conditions that proportionately iinfuences the quantity of gas molecules between the dynodes. The output current of the device is influenced by the reduction in electron multiplication at the dynodes due to energy reducing collisions of the electrons with the gas molecules between the dynodes. More particularly, the current is inversely proportional to the quantity of gas molecules, viz., the gas pressure. The device is, hence, extremely sensitive to low pressures.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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}.

  5. Development of transdermal therapeutic formulation of CNS5161, a novel NMDA receptor antagonist, by utilizing pressure-sensitive adhesives II: improved transdermal absorption and evaluation of efficacy and safety.

    PubMed

    Naruse, Mamoru; Ogawara, Ken-ichi; Kimura, Toshikiro; Konishi, Ryoji; Higaki, Kazutaka

    2014-02-14

    The aim of this study was to prepare a transdermal therapeutic formulation of CNS5161, an NMDA receptor antagonist developed as a drug for neuropathic pain. Since a silicone pressure-sensitive adhesive (PSA) was found to be the best PSA for CNS5161 among six different PSAs examined in our previous study, the effects of the loading concentration of CNS5161 on release and rat skin permeability were investigated using silicone PSAs. The release of CNS5161 was elevated with an increase in the drug concentration from 1% to 14%. The transdermal flux at the steady state reached a plateau at 8% and over, while crystallization of CNS5161 was not observed for any formulation even at high drug concentrations. The drug concentration in rat skin at the steady state was also saturated at 8% and over, which correlated well with the transdermal flux at the steady state. Therefore, skin permeation clearance defined to the skin concentration at the steady state was almost constant at 0.21/h from 2% to 14% of CNS5161, which suggests that drug concentrations in the skin would be a driving force for transport of the drug to the receptor side. Since increasing the concentration of CNS5161 in the PSA patch was not able to elevate the transdermal flux, 12 formulations containing several permeation enhancers were examined to improve the transdermal transport of CNS5161. Among them, the formulation containing propylene glycol, diisopropyl adipate, and polyvinylpyrrolidone significantly increased the transdermal flux by approximately 1.8-fold by improving the diffusivity of CNS5161 in the skin, and also significantly enhanced the analgesic effect of CNS5161. This formulation caused only slight skin irritation, which indicated that it would be a promising transdermal therapeutic system for CNS5161.

  6. 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.

  7. 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

  8. 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.

  9. Pressure-Sensitive Resistor Material

    NASA Technical Reports Server (NTRS)

    Du Fresne, E. R.

    1986-01-01

    Low-conductivity particles in rubber offer wide dynamic range. Sensor consists of particles of relatively low conductivity embedded in rubber. Resistance of sensor decreases by about 100 times as pressure on it increases from zero to 0.8 MN/M to the second power. Resistor promising candidate as tactile sensor for robots and remote manipulators.

  10. 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.

  11. Pressure-sensitive paint: effect of substrate.

    PubMed

    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.

  12. 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

  13. 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

  14. 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).

  15. 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.

  16. 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

  17. Large deformation contact mechanics of a pressurized long rectangular membrane. II. Adhesive contact

    PubMed Central

    Srivastava, Abhishek; Hui, Chung-Yuen

    2013-01-01

    In part I of this work, we presented a theory for adhesionless contact of a pressurized neo-Hookean plane-strain membrane to a rigid substrate. Here, we extend our theory to include adhesion using a fracture mechanics approach. This theory is used to study contact hysteresis commonly observed in experiments. Detailed analysis is carried out to highlight the differences between frictionless and no-slip contact. Membrane detachment is found to be strongly dependent on adhesion: for low adhesion, the membrane ‘pinches-off’, whereas for large adhesions, it detaches unstably at finite contact (‘pull-off’). Expressions are derived for the critical adhesion needed for pinch-off to pull-off transition. Above a threshold adhesion, the membrane exhibits bistability, two stable states at zero applied pressure. The condition for bistability for both frictionless and no-slip boundary conditions is obtained explicitly. PMID:24353472

  18. Adhesion

    MedlinePlus

    ... as the shoulder Eyes Inside the abdomen or pelvis Adhesions can become larger or tighter over time. ... Other causes of adhesions in the abdomen or pelvis include: Appendicitis , most often when the appendix breaks ...

  19. 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.

  20. 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.

  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. 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

  3. 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.

  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. [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

  6. Adhesions

    MedlinePlus

    ... surfaces so they can shift easily as the body moves. Adhesions cause tissues and organs to stick together. They might connect the loops of the intestines to each other, to nearby ... can occur anywhere in the body. But they often form after surgery on the ...

  7. 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

  8. A Sensitive and Biodegradable Pressure Sensor Array for Cardiovascular Monitoring.

    PubMed

    Boutry, Clementine M; Nguyen, Amanda; Lawal, Qudus Omotayo; Chortos, Alex; Rondeau-Gagné, Simon; Bao, Zhenan

    2015-11-18

    An array of highly sensitive pressure sensors entirely made of biodegradable materials is presented, designed as a single-use flexible patch for application in cardiovascular monitoring. The high sensitivity in combination with fast response time is unprecedented when compared to recent reports on biodegradable pressure sensors (sensitivity three orders of magnitude higher), as illustrated by pulse wave velocity measurements, toward hypertension detection.

  9. Adhesion force studies using a dangling optical lever with variable sensitivity.

    PubMed

    Panduputra, Yohannes; Ng, Tuck Wah; Neild, Adrian; Ling, William Yeong Liang

    2011-01-15

    Adhesion force sensed using tips on microcantilevers via an optical lever requires care to ensure that the tip alone contacts the liquid; is sensitive to high degrees of measurement error from departure from the laser spot; requires specialized optics and careful arrangement to produce a small laser probing spot; and limits the distance between cantilever and photodiode for increased force sensitivity. An alternative scheme, using microimaging electronic speckle pattern interferometry to monitor the deformation of a tipless microcantilever, necessitates that the beam be rigid enough to be independent of the drop location; is not amenable to very low adhesion force measurement; and requires more complicated instrumentation. All these limitations can be effectively circumvented by a variable sensitivity scheme described here that harnesses the geometric properties of a dangling cantilever operating as an optical lever. PMID:21263491

  10. 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.

  11. 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

  12. 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.

  13. Rosin (colophony) and zinc oxide in adhesive bandages. An appropriate combination for rosin-sensitive patients?

    PubMed

    Gäfvert, E; Färm, G

    1995-12-01

    Adhesives and bandages containing zinc oxide (ZnO) and rosin are often used for treatment of ulcers. The aim of this work was to study a possible inhibitory effect of ZnO on the elicitation of allergic contact reactions to rosin and to determine whether such an effect might be due to the formation of zinc resinates. Patch testing in rosin-sensitive patients was performed with mixes of ZnO and rosin. The eliciting capacities of one mix in which zinc resinates might be formed and another mix in which the formation of zinc resinates was prevented, were compared to the eliciting capacity of rosin alone. If a reduction of the allergic response was observed for the mix in which zinc resinates might form and if no reduction was observed for the mix in which formation of zinc resinates was prevented, this would support the hypothesis that the reduction in eliciting capacity was due to formation of zinc resinates. However, we could not see any difference in eliciting capacity when comparing the 2 mixes with a test preparation of rosin. Commercial adhesives (bandages) containing ZnO and rosin were patch tested in 7 rosin-sensitive patients. The concentration of abietic acid in the adhesives was determined with HPLC. Abietic acid was detected in all but one of those declared to contain rosin. The patients reacted to the adhesives in which abietic acid was detected. For rosin-sensitive persons, the addition of ZnO to rosin-containing adhesives cannot be regarded as an appropriate measure to inhibit the elicitation of allergic reactions.

  14. Prospective clinical study of a new adhesive gelling foam dressing in pressure ulcers.

    PubMed

    Parish, Lawrence Charles; Dryjski, Maciej; Cadden, Sue

    2008-03-01

    This prospective, non comparative study evaluated the safety and effectiveness of an adhesive gelling foam dressing in pressure ulcer management. Twenty-three subjects with exuding pressure ulcers were recruited from seven centres in the USA and Canada. Study treatment included an adhesive gelling foam dressing, optional tape/roll bandaging and mandatory pressure-reducing/relieving devices. Subjects were followed until ulcer healing, for up to 28 days, or on patient withdrawal from the study, whichever came first. Dressings were changed at least once every 7 days. Mean percentage change in ulcer area from baseline to final measurement was -13%. Investigators reported healing or subjective improvement of ulcer condition in 61% of patients. Mean dressing wear time was 4.2 days. Subjects found the dressing was comfortable, soothing and cushioning in situ at 80%, 64% and 70% of dressing changes, respectively. Subjects reported pain severity of none or mild for every dressing change. Fourteen subjects experienced adverse events, including seven subjects with study-related maceration, erythema, wound enlargement, blister or infection. A regimen including an adhesive gelling foam dressing proved to be safe and effective for managing exudate, protecting the surrounding skin, minimising pain and supporting healing of pressure ulcers with exudate.

  15. Extension and characterization of pressure-sensitive molecular film

    NASA Astrophysics Data System (ADS)

    Matsuda, Yu; Mori, Hideo; Sakazaki, Yoshiki; Uchida, Toru; Suzuki, Suguru; Yamaguchi, Hiroki; Niimi, Tomohide

    2009-12-01

    Pressure-sensitive paint (PSP) has the potential as a diagnostic tool for pressure measurement in high Knudsen number regime because it works as a so-called “molecular sensor”. However, there are few reports concerning application of PSP to micro-devices, because conventional PSPs are too thick owing to polymer binders. In our previous work, we adopted the Langmuir-Blodgett (LB) technique to fabricate the pressure-sensitive molecular film (PSMF) using Pd(II) Mesoporphyrin IX (PdMP), which has pressure sensitivity only in the low pressure range (below 130 Pa). In this study, aiming for pressure measurement under an atmospheric pressure condition, we have constructed four samples of PSMFs composed of Pt(II) Mesoporphyrin IX (PtMP), Pt(II) Mesoporphyrin IX dimethylester (PtMPDME), Pt(II) Protoporphyrin IX (PtPP) and Cu(II) Mesoporphyrin IX dimethylester (CuMPDME) as luminescent molecules. The pressure sensitivity of those PSMFs was measured, and it was clarified that the pressure sensitivity of PSMF-PtMP is the highest among the four samples. Moreover, the temperature dependency of PSMF-PtMP was investigated, and we found that the temperature dependency of PSMF is dominated not by the oxygen diffusion in the layer, but by non-radiative deactivation process of excited luminescent molecules.

  16. Pressure sensitivity of the vapor-cell atomic clock.

    PubMed

    Iyanu, Gebriel; Wang, He; Camparo, James

    2009-06-01

    Although atomic clocks have very low levels of frequency instability, they are nonetheless sensitive (albeit slightly) to various environmental parameters, including temperature, power supply voltage, and dc magnetic fields. In the terrestrial environment, however, atmospheric pressure (i.e., the air's molecular density) is not generally included in this list, because the air's density variations near the surface of the earth will typically have a negligible effect on the clock's performance. The situation is different, however, for clocks onboard satellites like Galileo, where manufacturing and testing are done at atmospheric pressure, while operation is in vacuum. The pressure sensitivity of atomic clocks, in particular vapor-cell atomic clocks, can therefore be of significance. Here, we discuss some of the ways in which changes in atmospheric pressure affect vapor-cell atomic clocks, and we demonstrate that, for one device, the pressure-sensitivity traces back to a pressure-induced change in the temperature of the clock's filter and resonance cells.

  17. [Orofacial touch and pressure sensitivity in children].

    PubMed

    Miura, Seiko

    2004-06-01

    This study assessed the thresholds of orofacial touch and pressure sensation in children and compared them with those in adults. Child subjects who were outpatients of TMDU Dental Hospital and who had no particular systemic diseases other than dental problems, were classified into 4 groups: preschool children (4-5 y, n=26), lower-grade elementary school pupils (6-9 y, n=100), higher-grade elementary school pupils (10-12 y, n=36), and junior high school pupils (13-15 y, n=26). Adult subjects were TMDU students (23-31 y, n=37). The thresholds of touch and pressure sensation were measured with a Semmes-Weinstein pressure aesthesiometer which consisted of 20 filaments with different marking values (Fm). Stimulation was applied with the thinner 10 filaments with lower values ranging from 1.65 to 4.31 Fm (0.0045-2.052 gw). The measurements were carried out on the following 10 points in the orofacial area in all the subjects: the upper lip, gingiva of upper anterior teeth, palate, lower lip, gingiva of lower anterior teeth, buccal mucous membrane, tongue tip, skin above eyebrow, cheek skin and mentum skin. The thresholds in the child subjects were not different from those in the adult subjects on most measurement points, but were significantly different on the gingiva and palate. The lower the age, the lower the thresholds on the gingiva. Since these measurement points are located in the chewing mucous membrane, it is considered that the threshold changes occurred due to histological alterations with growth. It is suggested that the threshold values of orofacial touch and pressure sensation obtained from this study could be used as the standard values for an indicator of the development of oral function and structure in children.

  18. 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.

  19. 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

  20. 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

  1. 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...

  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. 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

  5. Pressure-sensitive paint as a distributed optical microphone array.

    PubMed

    Gregory, James W; Sullivan, John P; Wanis, Sameh S; Komerath, Narayanan M

    2006-01-01

    Pressure-sensitive paint is presented and evaluated in this article as a quantitative technique for measurement of acoustic pressure fluctuations. This work is the culmination of advances in paint technology which enable unsteady measurements of fluctuations over 10 kHz at pressure levels as low as 125 dB. Pressure-sensitive paint may be thought of as a nano-scale array of optical microphones with a spatial resolution limited primarily by the resolution of the imaging device. Thus, pressure-sensitive paint is a powerful tool for making high-amplitude sound pressure measurements. In this work, the paint was used to record ensemble-averaged, time-resolved, quantitative measurements of two-dimensional mode shapes in an acoustic resonance cavity. A wall-mounted speaker generated nonlinear, standing acoustic waves in a rigid enclosure measuring 216 mm wide, 169 mm high, and 102 mm deep. The paint recorded the acoustic surface pressures of the (1,1,0) mode shape at approximately 1.3 kHz and a sound pressure level of 145.4 dB. Results from the paint are compared with data from a Kulite pressure transducer, and with linear acoustic theory. The paint may be used as a diagnostic technique for ultrasonic tests where high spatial resolution is essential, or in nonlinear acoustic applications such as shock tubes.

  6. 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.

  7. Development and characterization of fast responding pressure sensitive microspheres.

    PubMed

    Kimura, Fletcher; Rodriguez, Miguel; McCann, Jesse; Carlson, Brenden; Dabiri, Dana; Khalil, Gamal E; Callis, James B; Xia, Younan; Gouterman, Martin

    2008-07-01

    The response times of pressure sensitive paint (PSP) and pressure sensitive microspheres to passing shockwaves were measured to investigate their ability to accurately determine pressure changes in unsteady flows. The PSPs tested used platinum tetra(pentafluorophenyl)porphine (PtTFPP), platinum octaethylporphine (PtOEP), and a novel set of osmium-based organometallic complexes as pressure sensitive luminophors incorporated into polymer matrices of dimethylsiloxane bisphenol A-polycarbonate block copolymer or polystyrene. Two types of pressure sensitive microspheres were used, the first being PtOEP-doped polystyrene microspheres (PSBeads) and the second being porous silicon dioxide microspheres containing the novel, pressure sensitive osmium complexes. Response times for the platinum-based PSPs ranged from 47.2 to 53.0 micros, while the osmium-based PSPs ranged between 37.6 and 58.9 micros. For the microspheres, 2.5 microm diameter PSBeads showed a response time of 3.15 ms, while the osmium-based silicon dioxide microspheres showed a response time ranging between 13.6 and 18.9 micros.

  8. Film-based pressure-sensitive-paint measurements.

    PubMed

    Abbitt, J D; Fuentes, C A; Carroll, B F

    1996-11-15

    A technique to measure surface pressure distributions by use of pressure-sensitive paint and a novel filmbased imaging system is described. An oxygen-permeable photoluminescent paint is excited by narrow-band light centered at 455 nm. The resulting red-shifted luminescence (>570 nm) is imaged with a 35-mm film camera and digitized with a film scanner. The luminescence is quenched by oxygen, resulting in a logarithmic relationship between film density and pressure. An image collected at a reference condition is subtracted from an image obtained at the test condition and calibrated with known pressures. The resulting images are, to our knowledge, the first quantitative global surface measurements made with pressure-sensitive paint by a film-based imaging technique.

  9. The relevance of pressure-sensitive paint to aerodynamic research.

    PubMed

    Holmes, J W

    1993-09-01

    Aerodynamic tests are designed to give information about the performance of a model when subjected to an airflow. The introduction of pressure sensitive paint provides a new method for obtaining the pressure distribution on the surface of wind-tunnel models. A paint, the luminescence of which is dependent on air pressure, is applied to the surface of the model and the pressure distribution is obtained from the image produced. This paper gives an explanation of this technique, a résumé of possible applications and some results from research performed at DRA Bedford.

  10. 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.

  11. Low-pressure and atmospheric pressure plasma polymerized silica-like films as primers for adhesive bonding of aluminum

    NASA Astrophysics Data System (ADS)

    Gupta, Munish

    2007-12-01

    Plasma processes, including plasma etching and plasma polymerization, were investigated for the pretreatment of aluminum prior to structural adhesive bonding. Since native oxides of aluminum are unstable in the presence of moisture at elevated temperature, surface engineering processes must usually be applied to aluminum prior to adhesive bonding to produce oxides that are stable. Plasma processes are attractive for surface engineering since they take place in the gas phase and do not produce effluents that are difficult to dispose off. Reactive species that are generated in plasmas have relatively short lifetimes and form inert products. The objective of this work was to develop plasma etching and plasma polymerization as environmentally compatible processes for surface engineering of aluminum. Plasma polymerized silica-like films of thickness less than 200 nm were deposited on pretreated aluminum substrates using hexamethyldisiloxane (HMDSO) as the "monomer" and oxygen as a "co-reactant" in low-pressure RF-powered (13.6 MHz) reactor. Recently, plasma deposition at atmospheric pressure has become a promising technology because they do not require vacuum systems, can be applied to large objects with complex shapes, and adapted easily for continuous processing. Therefore, atmospheric pressure plasma processes were investigated and compared with their more traditional counterparts, low-pressure plasmas. Molecular structure and morphology of the plasma polymerized films were determined using surface analysis techniques such as X-ray photoelectron spectroscopy (XPS), fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The effectiveness of plasma etching and plasma polymerization as surface engineering processes for aluminum were probed by determining the initial strength and durability of aluminum/epoxy lap joints prepared from substrates that were plasma pretreated, coated with silica-like film, and

  12. 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.

  13. 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.

  14. A motion-capturing pressure-sensitive paint method

    NASA Astrophysics Data System (ADS)

    Sakaue, Hirotaka; Miyamoto, Kensuke; Miyazaki, Takeshi

    2013-02-01

    A motion-capturing pressure-sensitive paint (PSP) method is introduced to capture unsteady motions and flow fields of objects. Conventionally, the intensity-based method has been used to cancel the pressure-independent image of a PSP measurement to extract the pressure-dependent image. However, this method is not applicable if the pressure-independent image changes in time. The new motion-capturing method, namely imaging a two-color PSP-coated surface with a high-speed color camera, acquires both images simultaneously. This PSP has a reference luminescence in blue established using an appropriately tuned quantum dot, and a pressure-sensitive luminescence in red from bathophen ruthenium. The former has a luminescence spectrum from 400 to 550 nm, whereas the spectrum of the latter is around 620 nm. These are matched with the blue and red color ranges of the camera, which simultaneously acquires these images. By simply ratioing the blue and red images from each measurement, we can cancel the pressure-independent image, which are dependent on camera-PSP distance and illumination non-uniformity. The pressure sensitivity of the motion-capturing method is 1.12%/kPa which, due to the spectral overlap of the red and blue images, is slightly smaller than that of the intensity-based method by 0.01%/kPa. The response times are almost identical for both methods as both can respond to a step-pressure change within a time delay of 90 μs. A demonstration of this new method to sonic-jet impingement shows that the pressure-independent images can be used to cancel that component of the flow during unsteady motion and flows over a PSP-coated surface. The method can provide real-time pressure maps during unsteady motion created during a sonic jet impingement.

  15. 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.

  16. 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.

  17. Response time characterization of fast responding pressure-sensitive paint

    NASA Astrophysics Data System (ADS)

    Ozaki, Tatsuya; Ishikawa, Hitoshi; Sakaue, Hirotaka

    2010-11-01

    Response time characterization of a fast responding pressure-sensitive paint (PSP) is important information in measuring an unsteady flow field. PSP is an optical pressure sensor. The luminescent image from the PSP is related to a pressure map. In the previous works, a time delay from a step change of pressure is generally used to characterize the response time. The thickness of the PSP as well as the PSP binding material greatly influences the response time. Because the temperature influences the diffusion or permeation of a PSP binder, it is also an important parameter to influence the response time. We build a shock tube to create a step change of pressure for response time characterization. This can control the temperature of the PSP. We discuss the PSP response times related to the temperature of the binder as well as the binding materials.

  18. 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

  19. 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...

  20. Gecko adhesion: evolutionary nanotechnology.

    PubMed

    Autumn, Kellar; Gravish, Nick

    2008-05-13

    If geckos had not evolved, it is possible that humans would never have invented adhesive nanostructures. Geckos use millions of adhesive setae on their toes to climb vertical surfaces at speeds of over 1ms-1. Climbing presents a significant challenge for an adhesive in requiring both strong attachment and easy rapid removal. Conventional pressure-sensitive adhesives (PSAs) are either strong and difficult to remove (e.g. duct tape) or weak and easy to remove (e.g. sticky notes). The gecko adhesive differs dramatically from conventional adhesives. Conventional PSAs are soft viscoelastic polymers that degrade, foul, self-adhere and attach accidentally to inappropriate surfaces. In contrast, gecko toes bear angled arrays of branched, hair-like setae formed from stiff, hydrophobic keratin that act as a bed of angled springs with similar effective elastic modulus to that of PSAs. Setae are self-cleaning and maintain function for months during repeated use in dirty conditions. Setae are an anisotropic 'frictional adhesive' in that adhesion requires maintenance of a proximally directed shear load, enabling either a tough bond or spontaneous detachment. Gecko-like synthetic adhesives may become the glue of the future-and perhaps the screw of the future as well.

  1. 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

  2. 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

  3. Characterization of multi-dye pressure-sensitive microbeads

    NASA Astrophysics Data System (ADS)

    Lacroix, Daniel; Viraye-Chevalier, Teddy; Seiter, Guillaume; Howard, Jonathan; Dabiri, Dana; Khalil, Gamal E.; Xia, Younan; Zhu, Cun

    2013-11-01

    The response times of pressure-sensitive particles to passing shockwaves were measured to investigate their ability to accurately determine pressure changes in unsteady flows. The particles tested were loaded with novel pressure-sensitive dyes such as Pt (II) meso-tetra(pentafluorophenyl)porphine, Pt(II) octaethylporphine, bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl))iridium III, and iridium(III) bis(4-phenylthieno[3,2-c] pyridinato-N,C2')acetylacetonate. For this work, porous silicon dioxide pressure-sensitive beads (PSBeads) were used. Two synthetic procedures were used to fabricate the particles. In the first, a one-step method loaded dyes during the synthesis of microbeads, in the second a two-step method synthesized the microbeads first, then loaded the dyes. The shock tube facility was used to measure the response times of microbeads to fast pressure jumps. The study involved testing multiple luminophors loaded in microbeads with various size distributions. Response times for the silica-based microbeads ranged between 26 μs and 462 μs (at 90% of the amplitude response), which are much faster than previously reported polystyrene-based microbead response times, which range from 507 μs to 1582 μs (at 90% of the amplitude response) [F. Kimura, M. Rodriguez, J. McCann, B. Carlson, D. Dabiri, G. Khalil, J. B. Callis, Y. Xia, and M. Gouterman, "Development and characterization of fast responding pressure sensitive microspheres," Rev. Sci. Instrum. 79, 074102 (2008)].

  4. 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.

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

    PubMed

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

    2016-06-11

    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.

  6. 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

  7. 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

  8. Design optimization of high pressure and high temperature piezoresistive pressure sensor for high sensitivity

    NASA Astrophysics Data System (ADS)

    Niu, Zhe; Zhao, Yulong; Tian, Bian

    2014-01-01

    This paper describes a design method for optimizing sensitivity of piezoresistive pressure sensor in high-pressure and high-temperature environment. In order to prove the method, a piezoresistive pressure sensor (HPTSS) is designed. With the purpose of increasing sensitivity and to improve the measurement range, the piezoresistive sensor adopts rectangular membrane and thick film structure. The configuration of piezoresistors is arranged according to the characteristic of the rectangular membrane. The structure and configuration of the sensor chip are analyzed theoretically and simulated by the finite element method. This design enables the sensor chip to operate in high pressure condition (such as 150 MPa) with a high sensitivity and accuracy. The silicon on insulator wafer is selected to guarantee the thermo stability of the sensor chip. In order to optimize the fabrication and improve the yield of production, an electric conduction step is devised. Series of experiments demonstrates a favorable linearity of 0.13% and a high accuracy of 0.48%. And the sensitivity of HTPSS is about six times as high as a conventional square-membrane sensor chip in the experiment. Compared with the square-membrane pressure sensor and current production, the strength of HPTTS lies in sensitivity and measurement. The performance of the HPTSS indicates that it could be an ideal candidate for high-pressure and high-temperature sensing in real application.

  9. Design optimization of high pressure and high temperature piezoresistive pressure sensor for high sensitivity.

    PubMed

    Niu, Zhe; Zhao, Yulong; Tian, Bian

    2014-01-01

    This paper describes a design method for optimizing sensitivity of piezoresistive pressure sensor in high-pressure and high-temperature environment. In order to prove the method, a piezoresistive pressure sensor (HPTSS) is designed. With the purpose of increasing sensitivity and to improve the measurement range, the piezoresistive sensor adopts rectangular membrane and thick film structure. The configuration of piezoresistors is arranged according to the characteristic of the rectangular membrane. The structure and configuration of the sensor chip are analyzed theoretically and simulated by the finite element method. This design enables the sensor chip to operate in high pressure condition (such as 150 MPa) with a high sensitivity and accuracy. The silicon on insulator wafer is selected to guarantee the thermo stability of the sensor chip. In order to optimize the fabrication and improve the yield of production, an electric conduction step is devised. Series of experiments demonstrates a favorable linearity of 0.13% and a high accuracy of 0.48%. And the sensitivity of HTPSS is about six times as high as a conventional square-membrane sensor chip in the experiment. Compared with the square-membrane pressure sensor and current production, the strength of HPTTS lies in sensitivity and measurement. The performance of the HPTSS indicates that it could be an ideal candidate for high-pressure and high-temperature sensing in real application.

  10. Pressure-sensitive paint measurements of transient shock phenomena.

    PubMed

    Quinn, Mark Kenneth; Kontis, Konstantinos

    2013-04-02

    Measurements of the global pressure field created by shock wave diffraction have been captured optically using a porous pressure-sensitive paint. The pressure field created by a diffracting shock wave shows large increases and decreases in pressure and can be reasonably accurately captured using CFD. The substrate, a thin-layer chromatography (TLC) plate, has been dipped in a luminophore solution. TLC plates are readily available and easy to prepare. Illumination comes from two high-intensity broadband Xenon arc light sources with short-pass filters. The sample is imaged at 100 kHz using a Vision Research Phantom V710 in conjunction with a pair of long and short pass filters, creating a band. The PSP results are compared with numerical simulations of the flow using the commercial CFD package Fluent as part of ANSYS 13 for two Mach numbers.

  11. 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.

  12. 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.

  13. 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.

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

    PubMed

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

    2016-04-16

    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.

  15. 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.

  16. 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

  17. 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

  18. Applications of pressure-sensitive dielectric elastomer sensors

    NASA Astrophysics Data System (ADS)

    Böse, Holger; Ocak, Deniz; Ehrlich, Johannes

    2016-04-01

    Dielectric elastomer sensors for the measurement of compression loads with high sensitivity are described. The basic design of the sensors exhibits two profiled surfaces between which an elastomer film is confined. All components of the sensor were prepared with silicone whose stiffness can be varied in a wide range. Depending on details of the sensor design, various effects contribute to the enhancement of the capacitance. The intermediate elastomer film is stretched upon compression and electrode layers on the elastomer profiles and in the elastomer film approach each other. Different designs of the pressure sensor give rise to very different sensor characteristics in terms of the dependence of electric capacitance on compression force. Due to their inherent flexibility, the pressure sensors can be used on compliant substrates such as seats or beds or on the human body. This gives rise to numerous possible applications. The contribution describes also some examples of possible sensor applications. A glove was equipped with various sensors positioned at the finger tips. When grabbing an object with the glove, the sensors can detect the gripping forces of the individual fingers with high sensitivity. In a demonstrator of the glove equipped with seven sensors, the capacitances representing the gripping forces are recorded on a display. In another application example, a lower limb prosthesis was equipped with a pressure sensor to detect the load on the remaining part of the leg and the load is displayed in terms of the measured capacitance. The benefit of such sensors is to detect an eventual overload in order to prevent possible pressure sores. A third example introduces a seat load sensor system based on four extended pressure sensor mats. The sensor system detects the load distribution of a person on the seat. The examples emphasize the high performance of the new pressure sensor technology.

  19. 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

  20. 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.

  1. 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.

  2. Continuum modeling of a porous solid with pressure-sensitive dilatant matrix

    NASA Astrophysics Data System (ADS)

    Guo, T. F.; Faleskog, J.; Shih, C. F.

    The pressure-sensitive plastic response of a material has been studied in terms of the intrinsic sensitivity of its yield stress to pressure and the presence and growth of cavities. This work focuses on the interplay between these two distinctly different mechanisms and the attendant material behavior. To this end, a constitutive model is proposed taking both mechanisms into account. Using Gurson's homogenization, an upper bound model is developed for a voided solid with a plastically dilatant matrix material. This model is built around a three-parameter axisymmetric velocity field for a unit sphere containing a spherical void. The void is also subjected to internal pressure; this can be relevant for polymeric adhesives permeated by moisture that vaporizes at elevated temperatures. The plastic response of the matrix material is described by Drucker-Prager's yield criterion and an associated flow rule. The resulting yield surface and porosity evolution law of the homogenized constitutive model are presented in parametric form. Using the solutions to special cases as building blocks, approximate models with explicit forms are proposed. The parametric form and an approximate explicit form are compared against full-field solutions obtained from finite element analysis. They are also studied for loading under generalized tension conditions. These computational simulations shed light on the interplay between the two mechanisms and its enhanced effect on yield strength and plastic flow. Among other things, the tensile yield strength of the porous solid is greatly reduced by the internal void pressure, particularly when a liquid/vapor phase is the source of the internal pressure.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Sensitivity of pressure sensors enhanced by doping silver nanowires.

    PubMed

    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

  8. Comparison of unsteady pressure fields on turrets with different surface features using pressure-sensitive paint

    NASA Astrophysics Data System (ADS)

    Gordeyev, Stanislav; De Lucca, Nicholas; Jumper, Eric J.; Hird, Kyle; Juliano, Thomas J.; Gregory, James W.; Thordahl, James; Wittich, Donald J.

    2014-01-01

    Spatially temporally resolved unsteady pressure fields on a surface of a hemisphere-on-cylinder turret with either a flat or a conformal window with realistic features such as gaps and "smile" cutouts were characterized using fast-response pressure-sensitive paint at M = 0.33 for several window viewing angles. Various statistical properties of pressure fields were computed, and geometry effects on the unsteady pressure fields were analyzed and discussed. Proper orthogonal decomposition was also used to extract dominant pressure modes and corresponding temporal coefficients and to analyze and compare instantaneous pressure structures for different turret geometric features and the window viewing angles. An unsteady separation off the turret and a recirculation region downstream of the turret were identified as dominant sources of the unsteady pressure. It was found that while all geometric features affected the unsteady pressure field, the "smiles," positioned spanwise-symmetrically on both sides of the turret, were the leading cause of these changes, followed by the looking forward flat window. The gaps, the side- and the back-looking flat window introduced only small local changes.

  9. A graphene-based resistive pressure sensor with record-high sensitivity in a wide pressure range.

    PubMed

    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

    2015-02-27

    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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Development of electroluminescence based pressure-sensitive paint system

    NASA Astrophysics Data System (ADS)

    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.

  15. 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.

  16. 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.

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

    PubMed

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

    2016-03-08

    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.

  18. 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

  19. 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

  20. Wavenumber-frequency Spectra of Pressure Fluctuations Measured via Fast Response Pressure Sensitive Paint

    NASA Technical Reports Server (NTRS)

    Panda, J.; Roozeboom, N. H.; Ross, J. C.

    2016-01-01

    The recent advancement in fast-response Pressure-Sensitive Paint (PSP) allows time-resolved measurements of unsteady pressure fluctuations from a dense grid of spatial points on a wind tunnel model. This capability allows for direct calculations of the wavenumber-frequency (k-?) spectrum of pressure fluctuations. Such data, useful for the vibro-acoustics analysis of aerospace vehicles, are difficult to obtain otherwise. For the present work, time histories of pressure fluctuations on a flat plate subjected to vortex shedding from a rectangular bluff-body were measured using PSP. The light intensity levels in the photographic images were then converted to instantaneous pressure histories by applying calibration constants, which were calculated from a few dynamic pressure sensors placed at selective points on the plate. Fourier transform of the time-histories from a large number of spatial points provided k-? spectra for pressure fluctuations. The data provides first glimpse into the possibility of creating detailed forcing functions for vibro-acoustics analysis of aerospace vehicles, albeit for a limited frequency range.

  1. Anti-adhesive effect of poloxamer-based thermo-sensitive sol-gel in rabbit laminectomy model.

    PubMed

    Shin, Sung Joon; Lee, Jae Hyup; So, Jungwon; Min, Kyungdan

    2016-11-01

    Poloxamer-based thermo-sensitive sol-gel has been developed to reduce the incidence of postoperative scar formation at the laminectomy site. The purpose of this study was to evaluate the anti-adhesive effect of poloxamer based thermo-sensitive sol-gel compared to hyaluronate based solution after laminectomy, using a rabbit model. A thermo-sensitive anti-adhesive with a property of sol-gel transition was manufactured by a physical mixture of Poloxamer188/407, Chitosan and Gelatin. The viscosity in different temperatures was assessed. 72 adult New Zealand rabbits underwent lumbar laminectomy and were randomly divided into experimental (treated with the newly developed agent), positive (treated with hyaluronate based solution), and negative control groups. Each group was subdivided into 1 and 4-week subgroups. Gross and histological evaluations were performed to assess the extent of epidural adhesion. The experimental group showed significantly higher viscosity compared to the positive control group and showed a significant increase of viscosity as the temperature increased. Gross evaluation showed no statistically significant differences between the 1- and 4-week subgroups. However, histologic evaluation showed significant differences both in 1- and 4-week subgroups. Although the 4-week histologic results of the experimental and the positive control subgroups showed no significant difference, both subgroups revealed higher value compared to the negative control subgroup with regard to the ratio of adhesion less than 50 %. The new poloxamer based thermo-sensitive agent showed superior efficacy over the hyaluronate based agent at 1 week postoperatively. At 4 weeks postoperatively, there were no statistically significant differences between the two agents, although both showed efficacy over the sham group.

  2. Anti-adhesive effect of poloxamer-based thermo-sensitive sol-gel in rabbit laminectomy model.

    PubMed

    Shin, Sung Joon; Lee, Jae Hyup; So, Jungwon; Min, Kyungdan

    2016-11-01

    Poloxamer-based thermo-sensitive sol-gel has been developed to reduce the incidence of postoperative scar formation at the laminectomy site. The purpose of this study was to evaluate the anti-adhesive effect of poloxamer based thermo-sensitive sol-gel compared to hyaluronate based solution after laminectomy, using a rabbit model. A thermo-sensitive anti-adhesive with a property of sol-gel transition was manufactured by a physical mixture of Poloxamer188/407, Chitosan and Gelatin. The viscosity in different temperatures was assessed. 72 adult New Zealand rabbits underwent lumbar laminectomy and were randomly divided into experimental (treated with the newly developed agent), positive (treated with hyaluronate based solution), and negative control groups. Each group was subdivided into 1 and 4-week subgroups. Gross and histological evaluations were performed to assess the extent of epidural adhesion. The experimental group showed significantly higher viscosity compared to the positive control group and showed a significant increase of viscosity as the temperature increased. Gross evaluation showed no statistically significant differences between the 1- and 4-week subgroups. However, histologic evaluation showed significant differences both in 1- and 4-week subgroups. Although the 4-week histologic results of the experimental and the positive control subgroups showed no significant difference, both subgroups revealed higher value compared to the negative control subgroup with regard to the ratio of adhesion less than 50 %. The new poloxamer based thermo-sensitive agent showed superior efficacy over the hyaluronate based agent at 1 week postoperatively. At 4 weeks postoperatively, there were no statistically significant differences between the two agents, although both showed efficacy over the sham group. PMID:27646404

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. Effects of Antioxidant Supplementation on Insulin Sensitivity, Endothelial Adhesion Molecules and Oxidative Stress in Normal Weight and Overweight Young Adults

    PubMed Central

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

    2012-01-01

    Objective To determine whether short-term antioxidant supplementation affects insulin sensitivity, endothelial adhesion molecule levels, and oxidative stress in overweight young adults. Methods and Procedures A randomized, double-blind, controlled study tested the effects of antioxidants (AOX) on measures of insulin sensitivity (homeostasis model assessment, HOMA and QUICKI), endothelial adhesion molecules (sICAM-1, sVCAM-1, sE-selectin), adiponectin and oxidative stress (lipid hydroperoxides, PEROX) in overweight and normal weight individuals (N=48, 18-30 years). Participants received either AOX (vitamin E 800IU, vitamin C 500mg, β-carotene 10mg) or placebo (PLC) for 8 weeks. Results HOMA values were initially higher in the overweight subjects and were lowered with AOX by week 8 (15% reduction, p=0.02). Adiponectin increased in both AOX groups. sICAM-1 and sE-selectin decreased in overweight AOX treated groups by 6% and 13%, respectively (p<0.05). Plasma PEROX were reduced by 0.31 and 0.70 nmol/ml in the normal weight and overweight AOX treated groups, respectively, by week 8 (p<0.05). Discussion AOX 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 AOX are effective in suppressing diabetes or vascular activation over time. PMID:19154960

  9. Fast Pressure-Sensitive Paint for Flow and Acoustic Diagnostics

    NASA Astrophysics Data System (ADS)

    Gregory, James W.; Sakaue, Hirotaka; Liu, Tianshu; Sullivan, John P.

    2014-01-01

    The development and capabilities of fast-responding pressure-sensitive paint (fast PSP) are reviewed within the context of recent applications to aerodynamic and acoustic investigations. PSP is an optical technique for determining surface pressure distributions by measuring changes in the intensity of emitted light, whereas fast PSP is an extension applicable to unsteady flows and acoustics. Most fast PSP formulations are based on the development of porous binders that allow for rapid oxygen diffusion and interaction with the chemical sensor. This article reviews the development of porous binders, the selection of luminophore molecules suitable for unsteady testing, dynamic calibrations of PSP, data-acquisition methods, and noteworthy applications for flow and acoustic diagnostics. Calibrations of the dynamic response of fast PSP show a flat frequency response to at least 6 kHz, with some paint formulations exceeding a response of 1 MHz. Various applications of fast PSP are discussed that highlight the capabilities of the technique, and concluding remarks highlight the need for the future development of fast PSP.

  10. 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.

  11. 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

  12. A Versatile pH Sensitive Chondroitin Sulfate-PEG Tissue Adhesive and Hydrogel**

    PubMed Central

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

    2012-01-01

    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

  13. 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

  14. 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...

  15. N-Ethylmaleimide-sensitive Factor Attachment Protein α (αSNAP) Regulates Matrix Adhesion and Integrin Processing in Human Epithelial Cells*

    PubMed Central

    Naydenov, Nayden G.; Feygin, Alex; Wang, Lifu; Ivanov, Andrei I.

    2014-01-01

    Integrin-based adhesion to the extracellular matrix (ECM) plays critical roles in controlling differentiation, survival, and motility of epithelial cells. Cells attach to the ECM via dynamic structures called focal adhesions (FA). FA undergo constant remodeling mediated by vesicle trafficking and fusion. A soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein α (αSNAP) is an essential mediator of membrane fusion; however, its roles in regulating ECM adhesion and cell motility remain unexplored. In this study, we found that siRNA-mediated knockdown of αSNAP induced detachment of intestinal epithelial cells, whereas overexpression of αSNAP increased ECM adhesion and inhibited cell invasion. Loss of αSNAP impaired Golgi-dependent glycosylation and trafficking of β1 integrin and decreased phosphorylation of focal adhesion kinase (FAK) and paxillin resulting in FA disassembly. These effects of αSNAP depletion on ECM adhesion were independent of apoptosis and NSF. In agreement with our previous reports that Golgi fragmentation mediates cellular effects of αSNAP knockdown, we found that either pharmacologic or genetic disruption of the Golgi recapitulated all the effects of αSNAP depletion on ECM adhesion. Furthermore, our data implicates β1 integrin, FAK, and paxillin in mediating the observed pro-adhesive effects of αSNAP. These results reveal novel roles for αSNAP in regulating ECM adhesion and motility of epithelial cells. PMID:24311785

  16. 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.

  17. Macroalgal assemblage type affects predation pressure on sea urchins by altering adhesion strength.

    PubMed

    Gianguzza, P; Bonaviri, C; Milisenda, G; Barcellona, A; Agnetta, D; Vega Fernández, T; Badalamenti, F

    2010-07-01

    In the Mediterranean, sea breams are the most effective Paracentrotus lividus and Arbacia lixula predators. Generally, seabreams dislodge adult urchins from the rocky substrate, turn them upside down and crush their tests. Sea urchins may respond to fish attacks clinging tenaciously to the substratum. This study is the first attempt to investigate sea urchin adhesion strength in two alternative algal assemblages of the rocky infralittoral and valuated its possible implication for fish predation. We hypothesized that (1) sea urchin adhesion strength is higher in rocky shores dominated by encrusting macroalgae (ECA) than in erected macroalgae (EMA); (2) predation rates upon sea urchins are lower in ECA than in EMA; and (3) predation rate on A. lixula is lower than that on P. lividus. We observed that attachment tenacity of both sea urchins was higher in ECA than EMA and that A. lixula exhibited a stronger attachment tenacity than P. lividus in ECA. Results supported the importance of adhesion strength, as efficient defence against sea bream attacks, only for, P. lividus. A. lixula adhesion strength does not seem to be an important factor in avoiding fish predation, possibly because of the low palatability of the species. These patterns may deserve particular interest in understanding the processes responsible for the maintenance of sea urchin barrens that are dominated by ECA assemblage. PMID:20382419

  18. 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.

  19. Effects of non-thermal atmospheric pressure pulsed plasma on the adhesion and durability of resin composite to dentin.

    PubMed

    Han, Geum-Jun; Kim, Jae-Hoon; Chung, Sung-No; Chun, Bae-Hyeock; Kim, Chang-Keun; Seo, Deog-Gyu; Son, Ho-Hyun; Cho, Byeong-Hoon

    2014-12-01

    This study investigated the effect of low-power, non-thermal atmospheric pressure plasma (NT-APP) treatments, in pulsed and conventional modes, on the adhesion of resin composite to dentin and on the durability of the bond between resin composite and dentin. A pencil-type NT-APP jet was applied in pulsed and conventional modes to acid-etched dentin. The microtensile bond strength (MTBS) of resin composite to dentin was evaluated at 24 h and after thermocycling in one control group (no plasma) and in two experimental groups (pulsed plasma and conventional plasma groups) using the Scotchbond Multi-Purpose Plus Adhesive System. Data were analyzed using two-factor repeated-measures anova and Weibull statistics. Fractured surfaces and the bonded interfaces were evaluated using a field-emission scanning electron microscope. Although there were no significant differences between the plasma treatment groups, the plasma treatment improved the MTBS compared with the control group. After thermocycling, the MTBS did not decrease in the control or conventional plasma group but increased in the pulsed plasma group. Thermocycling increased the Weibull moduli of plasma-treated groups. In conclusion, plasma treatment using NT-APP improved the adhesion of resin composite to dentin. Using a pulsed energy source, the energy delivered to the dentin was effectively reduced without any reduction in bond strength or durability. PMID:25311730

  20. Effects of non-thermal atmospheric pressure pulsed plasma on the adhesion and durability of resin composite to dentin.

    PubMed

    Han, Geum-Jun; Kim, Jae-Hoon; Chung, Sung-No; Chun, Bae-Hyeock; Kim, Chang-Keun; Seo, Deog-Gyu; Son, Ho-Hyun; Cho, Byeong-Hoon

    2014-12-01

    This study investigated the effect of low-power, non-thermal atmospheric pressure plasma (NT-APP) treatments, in pulsed and conventional modes, on the adhesion of resin composite to dentin and on the durability of the bond between resin composite and dentin. A pencil-type NT-APP jet was applied in pulsed and conventional modes to acid-etched dentin. The microtensile bond strength (MTBS) of resin composite to dentin was evaluated at 24 h and after thermocycling in one control group (no plasma) and in two experimental groups (pulsed plasma and conventional plasma groups) using the Scotchbond Multi-Purpose Plus Adhesive System. Data were analyzed using two-factor repeated-measures anova and Weibull statistics. Fractured surfaces and the bonded interfaces were evaluated using a field-emission scanning electron microscope. Although there were no significant differences between the plasma treatment groups, the plasma treatment improved the MTBS compared with the control group. After thermocycling, the MTBS did not decrease in the control or conventional plasma group but increased in the pulsed plasma group. Thermocycling increased the Weibull moduli of plasma-treated groups. In conclusion, plasma treatment using NT-APP improved the adhesion of resin composite to dentin. Using a pulsed energy source, the energy delivered to the dentin was effectively reduced without any reduction in bond strength or durability.

  1. 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.

  2. 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

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

    PubMed

    Yu, Huiyang; Huang, Jianqiu

    2015-09-08

    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.

  4. 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

  5. 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.

  6. Design and fabrication of gecko-inspired adhesives.

    PubMed

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

    2012-04-01

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

  7. 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

  8. 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.

  9. Investigation of shear force of a single adhesion cell using a self-sensitive cantilever and fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Hashimoto, Shigetaka; Adachi, Makoto; Iwata, Futoshi

    2015-08-01

    In this paper, we describe a measurement system based on an atomic force microscope (AFM) for the measurement of the shear force and detachment energy of a single adhesion cell on a substrate. The shear force was quantitatively measured from the deflection of a self-sensitive cantilever that was employed for the simple configuration of the AFM manipulator. The shear force behavior of a single cell detaching from the substrate was observed. By staining cells with a fluorescence dye, the deformation shape of the cell being pushed with the cantilever could be clearly observed. The shear force and detachment energy of the cell increased with the size of the cell. The difference in the shear force of single cells on different substrates with different surface energies was quantitatively evaluated. The loading force applied to a single cell increased with the feed speed of the cantilever. The viability of cells after measurement under different feed speeds of the cantilever was also evaluated.

  10. 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.

  11. Low Pressure DC Glow Discharge Air Plasma Surface Treatment of Polyethylene (PE) Film for Improvement of Adhesive Properties

    NASA Astrophysics Data System (ADS)

    Krishnasamy Navaneetha, Pandiyaraj; Vengatasamy, Selvarajan; Rajendrasing, R. Deshmukh; Paramasivam, Yoganand; Suresh, Balasubramanian; Sundaram, Maruthamuthu

    2013-01-01

    The present work deals with the change in surface properties of polyethylene (PE) film using DC low pressure glow discharge air plasma and makes it useful for technical applications. The change in hydrophilicity of the modified PE film surface was investigated by measuring contact angle and surface energy as a function of exposure time. Changes in the morphological and chemical composition of PE films were analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The improvement in adhesion was studied by measuring T-peel and lap-shear strength. The results show that the wettability and surface energy of the PE film has been improved due to the introduction of oxygen-containing polar groups and an increase in surface roughness. The XPS result clearly shows the increase in concentration of oxygen content and the formation of polar groups on the polymer surface. The AFM observation on PE film shows that the roughness of the surface increased due to plasma treatment. The above morphological and chemical changes enhanced the adhesive properties of the PE film surfaces, which was confirmed by T-peel and lap-shear tests.

  12. 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

  13. 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.

  14. 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

  15. Graphene based polyurethane material: As highly pressure sensitive composite

    NASA Astrophysics Data System (ADS)

    Hodlur, R. M.; Rabinal, M. K.

    2012-06-01

    In our present work, we describe a simple method for uniform coating of Graphite oxide (GO) onto flexible polyurethane (PU) foams. These PU foams loaded with GO were made electrically conducting by converting insulating GO to conducting graphene by chemical reduction process without damaging the foam properties. These PU foams loaded with graphene were characterized by SEM and TGA. The morphology, thermal properties and pressure dependent electrical conductivity of these foams was studied. The electric current increased by five orders of magnitude due to applied pressure.

  16. 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.

  17. 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

  18. 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...

  19. A photostable bi-luminophore pressure-sensitive paint measurement system developed with mesoporous silica nanoparticles.

    PubMed

    Mochizuki, Dai; Tamura, Shinichi; Yasutake, Hiroaki; Kataoka, Tomoharu; Mitsuo, Kazunori; Wada, Yuji

    2013-04-01

    The accurate and high-resolution measurement of surface pressure is achieved by a pressure/ temperature-sensitive composite paint (bi-PSP), whereas the pressure-sensitive dye photodegraded the temperature sensitive dye in close arrangement of both dyes. In the present study, an attempt was made to synthesize a homogeneous bi-PSP membrane without light-induced degradation of the dye using mesoporous silica. Mesoporous silica as a molecular sieve was the separation of pressure- and temperature-sensitive dyes. Both achievement of control of photodegradation in temperature-sensitive paints with molecule-screening capacity and macroscopically uniform placement of insoluble pigments in the respective solvent, was accomplished using the mesoporous silica nanoparticles in a compound PSP.

  20. Oxygen sensitivity of photoluminescence intensity of Pt complex dispersed in fluorinated acrylate for pressure sensitive paint applications

    NASA Astrophysics Data System (ADS)

    Kwak, Jae Su; Choi, Yong Gyu

    2014-09-01

    Oxygen-sensitive photoluminescence intensity of a new combination of luminophore and matrix has been investigated for use in pressure sensitive paint applications. In consideration of oxygen permeability as well as optical transparency and structural stability, a fluorinated acrylate polymer is chosen as matrix in this study, where PtTFPP complex is dispersed and acts as luminophore responsible for the oxygen quenching. Processing conditions as to spin-coat films of the fluorinated acrylate doped with the PtTFPP are described. Pressure dependence of the photoluminescence emission of such spin-coat films is explained in connection with luminophore concentration, film thickness and types of substrate.

  1. 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.

  2. 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.

  3. 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

  4. Pressure-sensitive reaction yield of the TePixD blue-light sensor protein.

    PubMed

    Kuroi, Kunisato; Okajima, Koji; Ikeuchi, Masahiko; Tokutomi, Satoru; Kamiyama, Tadashi; Terazima, Masahide

    2015-02-19

    The effect of pressure on the dissociation reaction of the TePixD decamer was investigated by high-pressure transient grating (TG). The TG signal intensity representing the dissociation reaction of the TePixD decamer significantly decreased by applying a relatively small pressure. On the other hand, the reaction rate increased with increasing pressure. The equilibrium between the pentamer and the decamer was investigated by high-pressure dynamic light scattering. The results indicated that the fraction of the decamer slightly increased in the high-pressure region. From these measurements, it was concluded that the pressure-dependent signal intensity originated from the decrease of the quantum yield of the dissociation reaction of the decamer, indicating that this reaction efficiency is very sensitive to pressure. Using densimetry at high pressures, the compressibility was found to be pressure dependent even in a relatively low pressure range. We attributed the origin of the pressure-sensitive reaction yield to the decrease of compressibility at high pressure. Because the compressibility is related to the volume fluctuation, this observation suggests that the driving force for this reaction is fluctuation of the protein. The relationship between the cavities at the interfaces of the monomer units and the reactivity is also discussed.

  5. Stochastic sensitivity analysis for timing and amplitude of pressure waves in the arterial system.

    PubMed

    Eck, V G; Feinberg, J; Langtangen, H P; Hellevik, L R

    2015-04-01

    In the field of computational hemodynamics, sensitivity quantification of pressure and flow wave dynamics has received little attention. This work presents a novel study of the sensitivity of pressure-wave timing and amplitude in the arterial system with respect to arterial stiffness. Arterial pressure and flow waves were simulated with a one-dimensional distributed wave propagation model for compliant arterial networks. Sensitivity analysis of this model was based on a generalized polynomial chaos expansion evaluated by a stochastic collocation method. First-order statistical sensitivity indices were formulated to assess the effect of arterial stiffening on timing and amplitude of the pressure wave and backward-propagating pressure wave in the ascending aorta, at the maximum pressure and inflection point in the systolic phase. Only the stiffness of aortic arteries was found to significantly influence timing and amplitude of the backward-propagating pressure wave, whereas other large arteries in the systemic tree showed marginal impact. Furthermore, the ascending aorta, aortic arch, thoracic aorta, and infrarenal abdominal aorta had the largest influence on amplitude, whereas only the thoracic aorta influenced timing. Our results showed that the non-intrusive polynomial chaos expansion is an efficient method to compute statistical sensitivity measures for wave propagation models. These sensitivities provide new knowledge in the relative importance of arterial stiffness at various locations in the arterial network. Moreover, they will significantly influence clinical data collection and effective composition of the arterial tree for in-silico clinical studies.

  6. Carcinoembryonic antigen-related cell adhesion molecules as surrogate markers for EGFR inhibitor sensitivity in human lung adenocarcinoma

    PubMed Central

    Kobayashi, M; Miki, Y; Ebina, M; Abe, K; Mori, K; Narumi, S; Suzuki, T; Sato, I; Maemondo, M; Endo, C; Inoue, A; Kumamoto, H; Kondo, T; Yamada-Okabe, H; Nukiwa, T; Sasano, H

    2012-01-01

    Background: Lung adenocarcinoma (LADCA) patients with epidermal growth factor receptor (EGFR) mutations are in general associated with relatively high clinical response rate to EGFR-tyrosine kinase inhibitors (TKIs) but not all responded to TKI. It has therefore become important to identify the additional surrogate markers regarding EGFR-TKI sensitivity. Methods: We first examined the effects of EGFR-TKIs, gefitinib and erlotinib, upon cell proliferation of lung adenocarcinoma cell lines. We then evaluated the gene profiles related to EGFR-TKI sensitivity using a microarray analysis. Results of microarray analysis led us to focus on carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family, CEACAM 3, 5, 6, 7, and 19, as potential further surrogate markers of EGFR-TKI sensitivity. We then examined the correlation between the status of CEACAM 3, 5, 6, 7, and 19 immunoreactivity in LADCA and clinicopathological parameters of individual cases. Results: In the cases with EGFR mutations, the status of all CEACAMs examined was significantly higher than that in EGFR wild-type patients, but there were no significant differences in the status of CEACAMs between TKI responder and nonresponder among 22 patients who received gefitinib therapy. However, among 115 EGFR mutation-negative LADCA patients, both CEACAM6 and CEACAM3 were significantly associated with adverse clinical outcome (CEACAM6) and better clinical outcome (CEACAM3). Conclusion: CEACAMs examined in this study could be related to the presence of EGFR mutation in adenocarcinoma cells but not represent the effective surrogate marker of EGFR-TKI in LADCA patients. However, immunohistochemical evaluation of CEACAM3/6 in LADCA patients could provide important information on their clinical outcome. PMID:23099808

  7. 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.

  8. Single-shot, lifetime-based pressure-sensitive paint for rotating blades

    NASA Astrophysics Data System (ADS)

    Juliano, Thomas J.; Kumar, Pradeep; Peng, Di; Gregory, James W.; Crafton, Jim; Fonov, Sergey

    2011-08-01

    A single-shot, lifetime-based pressure-sensitive paint (PSP) technique is proposed as a pressure sensor for applications requiring high pressure sensitivity on a moving model such as a rotor blade. The method is based on a single pulse of high-energy excitation light and a double-frame exposure on an interline transfer charge-coupled device camera for recording luminescent lifetime. Small pressures can be measured on surfaces that are moving in an aperiodic manner (which precludes phase averaging). Measurements in environments having overall surface pressure gradients as small as 1 kPa show that the technique is capable of accurately resolving small pressure fluctuations. The pressure sensitivity to the oxygen concentration of some commonly available PSP formulations has been investigated with respect to capabilities and limitations of the paints for this single-shot lifetime application. A system with ruthenium-based pressure-sensitive paint, 532 nm wavelength laser and a CCD camera is demonstrated on a 0.126 m diameter propeller rotating at 70 Hz. Pressure data are acquired within a single pulse of excitation light energy, with no image averaging required.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. Atmospheric pressure plasma polymers for tuned QCM detection of protein adhesion.

    PubMed

    Rusu, G B; Asandulesa, M; Topala, I; Pohoata, V; Dumitrascu, N; Barboiu, M

    2014-03-15

    Our efforts have been concentrated in preparing plasma polymeric thin layers at atmospheric pressure grown on Quartz Crystal Microbalance-QCM electrodes for which the non-specific absorption of proteins can be efficiently modulated, tuned and used for QCM biosensing and quantification. Plasma polymerization reaction at atmospheric pressure has been used as a simple and viable method for the preparation of QCM bioactive surfaces, featuring variable protein binding properties. Polyethyleneglycol (ppEG), polystyrene (ppST) and poly(ethyleneglycol-styrene) (ppST-EG) thin-layers have been grown on QCM electrodes. These layers were characterized by Atomic Force Microscopy (AFM), Contact angle measurements, Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The plasma ppST QCM electrodes present a higher adsorption of Concanavalin A (ConA) and Bovine Serum Albumin (BSA) proteins when compared with the commercial coated polystyrene (ppST) ones. The minimum adsorption was found for ppEG, surface, known by their protein anti-fouling properties. The amount of adsorbed proteins can be tuned by the introduction of PEG precursors in the plasma discharge during the preparation of ppST polymers.

  15. 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

  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.

  17. 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.

  18. Temperature Cancellation Method of Motion-Capturing Pressure-Sensitive Paint System

    NASA Astrophysics Data System (ADS)

    Sakaue, Hirotaka; Yamada, Yuki; Okabe, Taika; Miyazaki, Takeshi

    2013-11-01

    Motion-capturing pressure-sensitive paint system uses two luminescent outputs to extract the pressure field on an aerodynamic object. This uses a luminescent imaging technique to relate the luminescent output to the pressure. In the previous study, this system is applied to capture the time-resolved unsteady pressure fields on a fluttering airfoil, and a bullet-shaped model. Pressure-sensitive paint (PSP) has a temperature dependency, which is a major error source for the PSP measurement. Motion-capturing PSP system also involves the temperature dependency of PSP itself. In the presentation, we propose a temperature-cancellation method of the motion-capturing PSP system. This method does not require a separate temperature measurement for the temperature correction that is advantage for capturing the pressure field on a moving object.

  19. 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.

  20. Pressure-sensitive paint measurement on co-rotating disks in a hard disk drive

    NASA Astrophysics Data System (ADS)

    Kameya, Tomohiro; Matsuda, Yu; Yamaguchi, Hiroki; Egami, Yasuhiro; Niimi, Tomohide

    2012-01-01

    There is much demand for improvement in the performance of a hard disk drive (HDD) along with recent rapid developments of information technology. While high-speed disk rotation of a HDD is necessary to accommodate such needs, it causes disk flutter induced by pressure fluctuation on disks and degrades reliability of a HDD. In order to understand the mechanism of the fluttering phenomenon, it is important to know pressure field on the rotating disk. However, it is impossible to measure the pressure by ordinary methods such as pressure taps. Pressure-sensitive paint (PSP) is a pressure measurement technique based on the oxygen quenching of luminescence and enables us to measure the pressure non-invasively. In general, however, the temperature sensitivity of PSP makes it difficult to measure the precise pressure on the surface with temperature distribution. We measured the time-averaged pressure on the disk rotating at 10 000-20 000 rpm for the first time by adopting a temperature-insensitive PSP composed of pyrene sulfonic acid (PySO 3H) as a luminophore. It was found that the pressure forms a concentric circular distribution and decreases toward the center of the disk. Additionally, we elucidate how disk rotational speed and spacing between co-rotating disks influence on the pressure field.

  1. Sensitivity analysis of aeroelastic response of a wing using piecewise pressure representation

    NASA Astrophysics Data System (ADS)

    Eldred, Lloyd B.; Kapania, Rakesh K.; Barthelemy, Jean-Francois M.

    1993-04-01

    A sensitivity analysis scheme of the static aeroelastic response of a wing is developed, by incorporating a piecewise panel-based pressure representation into an existing wing aeroelastic model to improve the model's fidelity, including the sensitivity of the wing static aeroelastic response with respect to various shape parameters. The new formulation is quite general and accepts any aerodynamics and structural analysis capability. A program is developed which combines the local sensitivities, such as the sensitivity of the stiffness matrix or the aerodynamic kernel matrix, into global sensitivity derivatives.

  2. In Situ Growth of Highly Adhesive Surface Layer on Titanium Foil as Durable Counter Electrodes for Efficient Dye-sensitized Solar Cells

    PubMed Central

    Liu, Wantao; Xu, Peng; Guo, Yanjun; Lin, Yuan; Yin, Xiong; Tang, Guangshi; He, Meng

    2016-01-01

    Counter electrodes (CEs) of dye-sensitized solar cells (DSCs) are usually fabricated by depositing catalytic materials on substrates. The poor adhesion of the catalytic material to the substrate often results in the exfoliation of catalytic materials, and then the deterioration of cell performance or even the failure of DSCs. In this study, a highly adhesive surface layer is in situ grown on the titanium foil via a facile process and applied as CEs for DSCs. The DSCs applying such CEs demonstrate decent power conversion efficiencies, 6.26% and 4.37% for rigid and flexible devices, respectively. The adhesion of the surface layer to the metal substrate is so strong that the photovoltaic performance of the devices is well retained even after the CEs are bended for 20 cycles and torn twice with adhesive tape. The results reported here indicate that the in situ growth of highly adhesive surface layers on metal substrate is a promising way to prepare durable CEs for efficient DSCs. PMID:27694905

  3. 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.

  4. TECHNICAL DESIGN NOTE: Effects of filters on the performance and characteristics of pressure-sensitive paints

    NASA Astrophysics Data System (ADS)

    Gongora-Orozco, N.; Zare-Behtash, H.; Kontis, K.

    2009-07-01

    The current study investigates the effect of four different filter combinations on the pressure sensitivity, signal level and temperature sensitivity of pressure-sensitive paint (PSP) samples in an a priori calibration. Two different PSP formulations developed at the Aero-Physics Laboratory are studied, one using hydrochloric acid (PSP1-HCl) and the other acetone (PSP2-Ace). Both are incorporated in a sol-gel solution. The results show that the effect of choosing different bandwidths, central wavelengths and transmissions of the filters for the emitted and excitation wavelengths can have a significant impact on the behaviour of PSP, luminescent signal level, pressure and temperature sensitivity, and also eliminate the undesired wavelengths which can affect the final results.

  5. 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.

  6. The pressure sensitivity of wrinkled B-doped nanocrystalline diamond membranes

    PubMed Central

    Drijkoningen, S.; Janssens, S. D.; Pobedinskas, P.; Koizumi, S.; Van Bael, M. K.; Haenen, K.

    2016-01-01

    Nanocrystalline diamond (NCD) membranes are promising candidates for use as sensitive pressure sensors. NCD membranes are able to withstand harsh conditions and are easily fabricated on glass. In this study the sensitivity of heavily boron doped NCD (B:NCD) pressure sensors is evaluated with respect to different types of supporting glass substrates, doping levels and membrane sizes. Higher pressure sensing sensitivities are obtained for membranes on Corning Eagle 2000 glass, which have a better match in thermal expansion coefficient with diamond compared to those on Schott AF45 glass. In addition, it is shown that larger and more heavily doped membranes are more sensitive. After fabrication of the membranes, the stress in the B:NCD films is released by the emergence of wrinkles. A better match between the thermal expansion coefficient of the NCD layer and the underlying substrate results in less stress and a smaller amount of wrinkles as confirmed by Raman spectroscopy and 3D surface imaging. PMID:27767048

  7. Unsteady pressure-sensitive paint measurement based on the heterodyne method using low frame rate camera

    NASA Astrophysics Data System (ADS)

    Matsuda, Yu; Yorita, Daisuke; Egami, Yasuhiro; Kameya, Tomohiro; Kakihara, Noriaki; Yamaguchi, Hiroki; Asai, Keisuke; Niimi, Tomohide

    2013-10-01

    The pressure-sensitive paint technique based on the heterodyne method was proposed for the precise pressure measurement of unsteady flow fields. This measurement is realized by detecting the beat signal that results from interference between a modulating illumination light source and a pressure fluctuation. The beat signal is captured by a camera with a considerably lower frame rate than the frequency of the pressure fluctuation. By carefully adjusting the frequency of the light and the camera frame rate, the signal at the frequency of interest is detected, while the noise signals at other frequencies are eliminated. To demonstrate the proposed method, we measured the pressure fluctuations in a resonance tube at the fundamental, second, and third harmonics. The pressure fluctuation distributions were successfully obtained and were consistent with measurements from a pressure transducer. The proposed method is a useful technique for measuring unsteady phenomena.

  8. Unsteady pressure-sensitive paint measurement based on the heterodyne method using low frame rate camera.

    PubMed

    Matsuda, Yu; Yorita, Daisuke; Egami, Yasuhiro; Kameya, Tomohiro; Kakihara, Noriaki; Yamaguchi, Hiroki; Asai, Keisuke; Niimi, Tomohide

    2013-10-01

    The pressure-sensitive paint technique based on the heterodyne method was proposed for the precise pressure measurement of unsteady flow fields. This measurement is realized by detecting the beat signal that results from interference between a modulating illumination light source and a pressure fluctuation. The beat signal is captured by a camera with a considerably lower frame rate than the frequency of the pressure fluctuation. By carefully adjusting the frequency of the light and the camera frame rate, the signal at the frequency of interest is detected, while the noise signals at other frequencies are eliminated. To demonstrate the proposed method, we measured the pressure fluctuations in a resonance tube at the fundamental, second, and third harmonics. The pressure fluctuation distributions were successfully obtained and were consistent with measurements from a pressure transducer. The proposed method is a useful technique for measuring unsteady phenomena.

  9. FBG sensor for temperature-independent high sensitive pressure measurement with aid of a Bourdon tube

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    A temperature independent high sensitive pressure sensing system using fiber Bragg grating (FBG) and `C' shaped Bourdon tube (CBT) is demonstrated. The sensor is configured by firmly fixing the FBG (FBG1) between free and fixed ends of the CBT. Additional FBG (FBG2) in line to the FBG1 is introduced which is shielded from the external pressure, tend to measure only the ambient temperature fluctuations. The CBT has an elliptical cross section where its free end is sealed and the fixed end is open for subjecting the liquid or gas pressure to be measured. With the application of pressure, the free end of CBT tends to straighten out results in an axial strain in FBG1 causes red shift in Bragg wavelength. The pressure can be determined by measuring the shift of the Bragg wavelength. The experimental pressure sensitivity is found to be 66.9 pm/psi over a range of 0 to 100 psi. The test results show that the Bragg wavelength shift is linear corresponds to change in applied pressure and well agreed with the simulated results. This simple and high sensitive design is capable of measuring static/dynamic pressure and temperature simultaneously which suits for industrial applications.

  10. 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

  11. 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.

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

    PubMed

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

    2015-03-03

    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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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

  19. Pressure monitoring over surfaces with sensitive paint by optical spectroscopy and intensity-based methods

    NASA Astrophysics Data System (ADS)

    García-Torales, Guillermo; Castrellón-Uribe, J.; Herrera Patiño, Enrique

    2009-09-01

    We present experimental results of monitoring pressure over samples painted with paint called Pressure Sensitive Paint (PSP), employing optical spectroscopy and imaging analysis. An electronic system to control pressure is implemented to restricted low pressure monitoring of the samples with PSP. The surface under analysis is excited with 370 nm wavelength (UV). The signal of fluorescence generated at 580 nm is correlated to variation of pressure over the interval of 4 to 200 kPa. As a complement, a set of images is acquired in the same interval of pressure. The images are processed and then lead to a set of histograms obtained from the samples images. We assess the transfer function of the system analyzing the histograms and the spectral response curves.

  20. 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.

  1. 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.

  2. Characterization and optimization of polymer-ceramic pressure-sensitive paint by controlling polymer content.

    PubMed

    Sakaue, Hirotaka; Kakisako, Takuma; Ishikawa, Hitoshi

    2011-01-01

    A pressure-sensitive paint (PSP) with fast response characteristics that can be sprayed on a test article is studied. This PSP consists of a polymer for spraying and a porous particle for providing the fast response. We controlled the polymer content (%) from 10 to 90% to study its effects on PSP characteristics: the signal level, pressure sensitivity, temperature dependency, and time response. The signal level and temperature dependency shows a peak in the polymer content around 50 to 70%. The pressure sensitivity was fairly constant in the range between 0.8 and 0.9 %/kPa. The time response is improved by lowering the polymer content. The variation of the time response is shown to be on the order of milliseconds to ten seconds. A weight coefficient is introduced to optimize the resultant PSPs. By setting the weight coefficient, we can optimize the PSP for sensing purposes.

  3. 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.

  4. 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.

  5. Highly Sensitive and Patchable Pressure Sensors Mimicking Ion-Channel-Engaged Sensory Organs.

    PubMed

    Chun, Kyoung-Yong; Son, Young Jun; Han, Chang-Soo

    2016-04-26

    Biological ion channels have led to much inspiration because of their unique and exquisite operational functions in living cells. Specifically, their extreme and dynamic sensing abilities can be realized by the combination of receptors and nanopores coupled together to construct an ion channel system. In the current study, we demonstrated that artificial ion channel pressure sensors inspired by nature for detecting pressure are highly sensitive and patchable. Our ion channel pressure sensors basically consisted of receptors and nanopore membranes, enabling dynamic current responses to external forces for multiple applications. The ion channel pressure sensors had a sensitivity of ∼5.6 kPa(-1) and a response time of ∼12 ms at a frequency of 1 Hz. The power consumption was recorded as less than a few μW. Moreover, a reliability test showed stability over 10 000 loading-unloading cycles. Additionally, linear regression was performed in terms of temperature, which showed no significant variations, and there were no significant current variations with humidity. The patchable ion channel pressure sensors were then used to detect blood pressure/pulse in humans, and different signals were clearly observed for each person. Additionally, modified ion channel pressure sensors detected complex motions including pressing and folding in a high-pressure range (10-20 kPa).

  6. Measurement of transient acoustic fields using a single-shot pressure-sensitive paint system.

    PubMed

    Disotell, Kevin J; Gregory, James W

    2011-07-01

    A pressure-sensitive paint (PSP) system capable of measuring high-frequency acoustic fields with non-periodic, acoustic-level pressure changes is described. As an optical measurement technique, PSP provides the experimenter with a global distribution of pressure on a painted surface. To demonstrate frequency response and enhanced sensitivity to pressure changes, a PSP system consisting of a polymer∕ceramic matrix binder with platinum tetra(pentafluorophenyl) porphyrin (PtTFPP) as the oxygen probe was applied to a wall inside an acoustic resonance cavity excited at 1.3 kHz. A data acquisition technique based on the luminescent decay lifetime of the oxygen sensors excited by a single pulse of light afforded the ability to capture instantaneous pressure fields with no phase-averaging. Superimposed wave-like structures were observed with a wavelength corresponding to a 4.7% difference from the theoretical value for a sound wave emanating from the speaker. High sound pressure cases upwards of 145 dB (re 20 μPa) exhibited skewed nodal lines attributed to a nonlinear acoustic field. The lowest sound pressure level of 125.4 dB--corresponding to an amplitude of 52.7 Pa, or approximately 0.05% of standard sea-level atmospheric pressure--showed that the paint could resolve the spatial details of the mode shape at the given resonance condition.

  7. Measurement of transient acoustic fields using a single-shot pressure-sensitive paint system.

    PubMed

    Disotell, Kevin J; Gregory, James W

    2011-07-01

    A pressure-sensitive paint (PSP) system capable of measuring high-frequency acoustic fields with non-periodic, acoustic-level pressure changes is described. As an optical measurement technique, PSP provides the experimenter with a global distribution of pressure on a painted surface. To demonstrate frequency response and enhanced sensitivity to pressure changes, a PSP system consisting of a polymer∕ceramic matrix binder with platinum tetra(pentafluorophenyl) porphyrin (PtTFPP) as the oxygen probe was applied to a wall inside an acoustic resonance cavity excited at 1.3 kHz. A data acquisition technique based on the luminescent decay lifetime of the oxygen sensors excited by a single pulse of light afforded the ability to capture instantaneous pressure fields with no phase-averaging. Superimposed wave-like structures were observed with a wavelength corresponding to a 4.7% difference from the theoretical value for a sound wave emanating from the speaker. High sound pressure cases upwards of 145 dB (re 20 μPa) exhibited skewed nodal lines attributed to a nonlinear acoustic field. The lowest sound pressure level of 125.4 dB--corresponding to an amplitude of 52.7 Pa, or approximately 0.05% of standard sea-level atmospheric pressure--showed that the paint could resolve the spatial details of the mode shape at the given resonance condition. PMID:21806232

  8. All-fiber high-sensitivity pressure sensor with SiO2 diaphragm.

    PubMed

    Donlagic, Denis; Cibula, Edvard

    2005-08-15

    The design and fabrication of a miniature fiber Fabry-Perot pressure sensor with a diameter of 125 microm are presented. The essential element in the process is a thin SiO2 diaphragm that is fusion spliced at the hollow end of an optical fiber. Good repeatability and high sensitivity of the sensor are achieved by on-line tuning of the diaphragm thickness during the sensor fabrication process. Various sensor prototypes were fabricated, demonstrating pressure ranges of from 0 to 40 kPa to 0 to 1 MPa. The maximum achieved sensitivity was 1.1 rad/40 kPa at 1550 nm, and a pressure resolution of 300 Pa was demonstrated in practice. The presented design and fabrication technique offers a means of simple and low-cost disposable pressure sensor production. PMID:16127913

  9. Mimosa-inspired design of a flexible pressure sensor with touch sensitivity.

    PubMed

    Su, Bin; Gong, Shu; Ma, Zheng; Yap, Lim Wei; Cheng, Wenlong

    2015-04-24

    A bio-inspired flexible pressure sensor is generated with high sensitivity (50.17 kPa(-1)), quick responding time (<20 ms), and durable stability (negligible loading-unloading signal changes over 10 000 cycles). Notably, the key resource of surface microstructures upon sensor substrates results from the direct molding of natural mimosa leaves, presenting a simple, environment-friendly and easy scale-up fabrication process for these flexible pressure sensors.

  10. Development of Pressure-Sensitive Channel Chip for Micro Gas Flows

    NASA Astrophysics Data System (ADS)

    Matsuda, Yu; Yamaguchi, Hiroki; Niimi, Tomohide

    2012-05-01

    Optical measurement techniques are useful for experimental studies on micro gas flows, which enable us to non-intrusively measure the flows with a high spatial resolution. The pressure-sensitive paint (PSP) technique, which is based on the emission of photons from luminophore, is a potential diagnostic tool for pressure measurement of micro gas flows. However, measurements by conventional PSPs are limited to the sub-millimeter order spatial resolution of ca. 200 μm, indicating the difficulty of the micro scale measurements. The present study proposes pressure-sensitive channel chip (PSCC) which is a micro channel with the capability of measuring pressure. We focused on the poly (dimethylsiloxane) (PDMS) micro-molding technique, which is one of the most popular techniques to fabricate a micro channel easily. Moreover, PDMS is a polymer used as a binder in PSP because of high optical transparency, gas permeability, and gas diffusivity. Thus, we developed a micro channel by the PDMS micro-molding technique with mixing a pressure-sensitive luminophore into PDMS: i.e. a micro channel fabricated by PSP, which is named PSCC. A flow through a micro converging-diverging nozzle with the throat width of 120 μm was demonstrated. The pressure distribution on the nozzle surface was successfully obtained by PSCC.

  11. Deuterium oxide normalizes blood pressure and vascular calcium uptake in Dahl salt-sensitive hypertensive rats

    SciTech Connect

    Vasdev, S.; Prabhakaran, V.; Sampson, C.A. )

    1990-02-01

    This study examined the effect of 25% deuterium oxide in drinking water on systolic blood pressure, uptakes of calcium, and rubidium 86 by aortas of Dahl salt-sensitive rats on 0.4% (low) and 8% (high) sodium chloride (salt) diet. Twenty-four rats were divided into four groups. Groups I and II were on the low salt diet and groups III and IV on the high salt diet from 6 weeks of age. Additionally, at 10 weeks of age groups I and III were placed on 100% water and groups II and IV on 25% deuterium oxide. At 14 weeks, systolic blood pressure, uptakes of calcium, and rubidium 86 by aortas were significantly higher (p less than 0.01) in rats on the high salt diet as compared with those on the low salt diet. Deuterium oxide intake normalized systolic blood pressure and aortic calcium uptake but not aortic rubidium 86 uptake in hypertensive rats on the high salt diet. Deuterium oxide had no effect on blood pressure or aortic calcium uptake in rats on the low salt diet. The parallel increase in systolic blood pressure and vascular calcium uptake suggests that increased calcium uptake mechanisms are associated with hypertension in salt-sensitive Dahl rats. Furthermore, deuterium oxide appears to normalize elevated blood pressure in salt-sensitive hypertensive rats by normalizing elevated vascular (aortic) calcium uptake.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. Quantification aspects of constant pressure (ultra) high pressure liquid chromatography using mass-sensitive detectors with a nebulizing interface.

    PubMed

    Verstraeten, M; Broeckhoven, K; Lynen, F; Choikhet, K; Landt, K; Dittmann, M; Witt, K; Sandra, P; Desmet, G

    2013-01-25

    The present contribution investigates the quantitation aspects of mass-sensitive detectors with nebulizing interface (ESI-MSD, ELSD, CAD) in the constant pressure gradient elution mode. In this operation mode, the pressure is controlled and maintained at a set value and the liquid flow rate will vary according to the inverse mobile phase viscosity. As the pressure is continuously kept at the allowable maximum during the entire gradient run, the average liquid flow rate is higher compared to that in the conventional constant flow rate operation mode, thus shortening the analysis time. The following three mass-sensitive detectors were investigated: mass spectrometry detector (MS), evaporative light scattering detector (ELSD) and charged aerosol detector (CAD) and a wide variety of samples (phenones, polyaromatic hydrocarbons, wine, cocoa butter) has been considered. It was found that the nebulizing efficiency of the LC-interfaces of the three detectors under consideration changes with the increasing liquid flow rate. For the MS, the increasing flow rate leads to a lower peak area whereas for the ELSD the peak area increases compared to the constant flow rate mode. The peak area obtained with a CAD is rather insensitive to the liquid flow rate. The reproducibility of the peak area remains similar in both modes, although variation in system permeability compromises the 'long-term' reproducibility. This problem can however be overcome by running a flow rate program with an optimized flow rate and composition profile obtained from the constant pressure mode. In this case, the quantification remains reproducibile, despite any occuring variations of the system permeability. Furthermore, the same fragmentation pattern (MS) has been found in the constant pressure mode compared to the customary constant flow rate mode.

  17. Measurement of transient acoustic fields using a single-shot pressure-sensitive paint system

    NASA Astrophysics Data System (ADS)

    Disotell, Kevin J.; Gregory, James W.

    2011-07-01

    A pressure-sensitive paint (PSP) system capable of measuring high-frequency acoustic fields with non-periodic, acoustic-level pressure changes is described. As an optical measurement technique, PSP provides the experimenter with a global distribution of pressure on a painted surface. To demonstrate frequency response and enhanced sensitivity to pressure changes, a PSP system consisting of a polymer/ceramic matrix binder with platinum tetra(pentafluorophenyl) porphyrin (PtTFPP) as the oxygen probe was applied to a wall inside an acoustic resonance cavity excited at 1.3 kHz. A data acquisition technique based on the luminescent decay lifetime of the oxygen sensors excited by a single pulse of light afforded the ability to capture instantaneous pressure fields with no phase-averaging. Superimposed wave-like structures were observed with a wavelength corresponding to a 4.7% difference from the theoretical value for a sound wave emanating from the speaker. High sound pressure cases upwards of 145 dB (re 20 μPa) exhibited skewed nodal lines attributed to a nonlinear acoustic field. The lowest sound pressure level of 125.4 dB—corresponding to an amplitude of 52.7 Pa, or approximately 0.05% of standard sea-level atmospheric pressure—showed that the paint could resolve the spatial details of the mode shape at the given resonance condition.

  18. Sensitivity of stress inversion of focal mechanisms to pore pressure changes

    NASA Astrophysics Data System (ADS)

    Martínez-Garzón, Patricia; Vavryčuk, Václav; Kwiatek, Grzegorz; Bohnhoff, Marco

    2016-08-01

    We investigate the sensitivity of stress inversion from focal mechanisms to pore pressure changes. Synthetic tests reveal that pore pressure variations can cause apparent changes in the retrieved stress ratio R relating the magnitude of the intermediate principal stress with respect to the maximum and minimum principal stresses. Pore pressure and retrieved R are negatively correlated when R is low (R < 0.6). The spurious variations in retrieved R are suppressed when R > 0.6. This observation is independent of faulting style, and it may be related to different performance of the fault plane selection criterion and variability in orientation of activated faults under different pore pressures. Our findings from synthetic data are supported by results obtained from induced seismicity at The Geysers geothermal field. Therefore, the retrieved stress ratio variations can be utilized for monitoring pore pressure changes at seismogenic depth in stress domains with overall low R.

  19. 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.

  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. 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.

  2. 75 FR 8925 - Pressure Sensitive Plastic Tape from Italy: Preliminary Results of Antidumping Duty Changed...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-26

    ... Pressure Sensitive Plastic Tape From Italy; Determination of Injury or Likelihood Thereof, 42 FR 44853... Changed Circumstances Review, 74 FR 47555 (September 16, 2009). On October 26, 2009, the Department placed... of Final Results of Changed Circumstances Review: Polychloroprene Rubber from Japan, 69 FR...

  3. Comparison of the sensitivity of mass spectrometry atmospheric pressure ionization techniques in the analysis of porphyrinoids.

    PubMed

    Swider, Paweł; Lewtak, Jan P; Gryko, Daniel T; Danikiewicz, Witold

    2013-10-01

    The porphyrinoids chemistry is greatly dependent on the data obtained in mass spectrometry. For this reason, it is essential to determine the range of applicability of mass spectrometry ionization methods. In this study, the sensitivity of three different atmospheric pressure ionization techniques, electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization, was tested for several porphyrinods and their metallocomplexes. Electrospray ionization method was shown to be the best ionization technique because of its high sensitivity for derivatives of cyanocobalamin, free-base corroles and porphyrins. In the case of metallocorroles and metalloporphyrins, atmospheric pressure photoionization with dopant proved to be the most sensitive ionization method. It was also shown that for relatively acidic compounds, particularly for corroles, the negative ion mode provides better sensitivity than the positive ion mode. The results supply a lot of relevant information on the methodology of porphyrinoids analysis carried out by mass spectrometry. The information can be useful in designing future MS or liquid chromatography-MS experiments.

  4. A dipping duration study for optimization of anodized-aluminum pressure-sensitive paint.

    PubMed

    Sakaue, Hirotaka; Ishii, Keiko

    2010-01-01

    Anodized-aluminum pressure-sensitive paint (AA-PSP) uses the dipping deposition method to apply a luminophore on a porous anodized-aluminum surface. We study the dipping duration, one of the parameters of the dipping deposition related to the characterization of AA-PSP. The dipping duration was varied from 1 to 100,000 s. The properties characterized are the pressure sensitivity, temperature dependency, and signal level. The maximum pressure sensitivity of 65% is obtained at the dipping duration of 100 s, the minimum temperature dependency is obtained at the duration of 1 s, and the maximum signal level is obtained at the duration of 1,000 s, respectively. Among the characteristics, the dipping duration most influences the signal level. The change in the signal level is a factor of 8.4. By introducing a weight coefficient, an optimum dipping duration can be determined. Among all the dipping parameters, such as the dipping duration, dipping solvent, and luminophore concentration, the pressure sensitivity and signal level are most influenced by the dipping solvent.

  5. Optimization of anodized-aluminum pressure-sensitive paint by controlling luminophore concentration.

    PubMed

    Sakaue, Hirotaka; Ishii, Keiko

    2010-01-01

    Anodized-aluminum pressure-sensitive paint (AA-PSP) has been used as a global pressure sensor for unsteady flow measurements. We use a dipping deposition method to apply a luminophore on a porous anodized-aluminum surface, controlling the luminophore concentration of the dipping method to optimize AA-PSP characteristics. The concentration is varied from 0.001 to 10 mM. Characterizations include the pressure sensitivity, the temperature dependency, and the signal level. The pressure sensitivity shows around 60 % at a lower concentration up to 0.1 mM. Above this concentration, the sensitivity reduces to a half. The temperature dependency becomes more than a half by setting the luminophore concentration from 0.001 to 10 mM. There is 3.6-fold change in the signal level by varying the concentration. To discuss an optimum concentration, a weight coefficient is introduced. We can arbitrarily change the coefficients to create an optimized AA-PSP for our sensing purposes.

  6. 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

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

    PubMed

    Pandey, Anshuman; Gregory, James W

    2015-09-03

    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.

  8. 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

  9. 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

  10. Compressible fiber optic micro-Fabry-Pérot cavity with ultra-high pressure sensitivity.

    PubMed

    Wang, Ying; Wang, D N; Wang, Chao; Hu, Tianyi

    2013-06-17

    We propose and demonstrate a pressure sensor based on a micro air bubble at the end facet of a single mode fiber fusion spliced with a silica tube. When immersed into the liquid such as water, the air bubble essentially acts as a Fabry-Pérot interferometer cavity. Such a cavity can be compressed by the environmental pressure and the sensitivity obtained is >1000 nm/kPa, at least one order of magnitude higher than that of the diaphragm-based fiber-tip sensors reported so far. The compressible Fabry-Pérot interferometer cavity developed is expected to have potential applications in highly sensitive pressure and/or acoustic sensing.

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

    PubMed

    Meng, Xiawei; Zhao, Yulong

    2016-03-09

    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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Spatially digitized tactile pressure sensors with tunable sensitivity and sensing range

    NASA Astrophysics Data System (ADS)

    Choi, Eunsuk; Sul, Onejae; Hwang, Soonhyung; Cho, Joonhyung; Chun, Hyunsuk; Kim, Hongjun; Lee, Seung-Beck

    2014-10-01

    When developing an electronic skin with touch sensation, an array of tactile pressure sensors with various ranges of pressure detection need to be integrated. This requires low noise, highly reliable sensors with tunable sensing characteristics. We demonstrate the operation of tactile pressure sensors that utilize the spatial distribution of contact electrodes to detect various ranges of tactile pressures. The device consists of a suspended elastomer diaphragm, with a carbon nanotube thin-film on the bottom, which makes contact with the electrodes on the substrate with applied pressure. The electrodes separated by set distances become connected in sequence with tactile pressure, enabling consecutive electrodes to produce a signal. Thus, the pressure is detected not by how much of a signal is produced but by which of the electrodes is registering an output. By modulating the diaphragm diameter, and suspension height, it was possible to tune the pressure sensitivity and sensing range. Also, adding a fingerprint ridge structure enabled the sensor to detect the periodicity of sub-millimeter grating patterns on a silicon wafer.

  17. 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

  18. An atmospheric-pressure plasma-treated titanium surface potentially supports initial cell adhesion, growth, and differentiation of cultured human prenatal-derived osteoblastic cells.

    PubMed

    Kawase, Tomoyuki; Tanaka, Takaaki; Minbu, Hiromi; Kamiya, Mana; Oda, Masafumi; Hara, Toshiaki

    2014-08-01

    An atmospheric-pressure plasma (APP) treatment was recently reported to render titanium (Ti) surfaces more suitable for osteoblastic cell proliferation and osteogenesis. However, the mechanism of action remains to be clearly demonstrated. In this study, we focused on cell adhesion and examined the effects of the APP treatment on the initial responses of human prenatal-derived osteoblastic cells incubated on chemically polished commercially pure Ti (CP-cpTi) plates. In the medium containing 1% fetal bovine serum, the initial cell adhesion and the actin polymerization were evaluated by scanning electron microscopy and fluorescence microscopy. The expression of cell adhesion-related molecules and osteoblast markers at the messenger RNA level was assessed by real-time quantitative polymerase chain reaction. Although the cells on the APP-treated CP-cpTi surface developed fewer cytoskeletal actin fibers, they attached with higher affinity and consequently proliferated more actively (1.46-fold over control at 72 h). However, most of the cell adhesion molecule genes were significantly downregulated (from 40 to 85% of control) in the cells incubated on the APP-treated CP-cpTi surface at 24 h. Similarly, the osteoblast marker genes were significantly downregulated (from 49 to 63% of control) at 72 h. However, the osteoblast marker genes were drastically upregulated (from 197 to 296% of control) in these cells by dexamethasone and β-glycerophosphate treatment. These findings suggest that the APP treatment improves the ability of the CP-cpTi surface to support osteoblastic proliferation by enhancing the initial cell adhesion and supports osteoblastic differentiation when immature osteoblasts begin the differentiation process.

  19. 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.

  20. 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.

  1. 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.

  2. 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

    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 [Formula: see text] 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.

  3. 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

  4. 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

  5. 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).

  6. 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

  7. 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.

  8. 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.

  9. Dual luminophor pressure-sensitive paint: III. Application to automotive model testing

    NASA Astrophysics Data System (ADS)

    Gouterman, Martin; Callis, James; Dalton, Larry; Khalil, Gamal; Mébarki, Youssef; Cooper, Kevin R.; Grenier, Michel

    2004-10-01

    Porphyrins play key roles in natural energy conversion systems, including photosynthesis and oxygen transport. Because of their chemical stability, unique optical properties and synthetic versatility, porphyrins are well suited as chemical sensors. One successful application is the use of platinum porphyrin (PtP) in pressure-sensitive paint (PSP). Oxygen in the film quenches luminescence, and oxygen pressure was initially monitored by measuring the ratio of I(wind-off)/I(wind-on). But this ratio is compromised if there is model motion and if the paint layer is inhomogeneous. Furthermore it requires careful monitoring and placement of light sources. Moreover, this method is seriously affected by temperature. The errors caused by model motion and temperature sensitivity are eliminated or greatly reduced using dual luminophor paint. This paper illustrates a successful application of a dual luminophor PSP in auto model testing. The PSP is made from an oxygen sensitive luminophor, Pt tetra(pentafluorophenyl)-porpholactone, which provides Isen, and Mg tetra(pentafluorophenyl)porphine, which provides temperature-sensitive paint (TSP) as the pressure-independent reference. The ratio PSP/TSP in the FIB polymer produced ideal PSP measurements with a very low-temperature dependence of -0.1% °C-1.

  10. Sympathoexcitation by oxidative stress in the brain mediates arterial pressure elevation in salt-sensitive hypertension.

    PubMed

    Fujita, Megumi; Ando, Katsuyuki; Nagae, Ai; Fujita, Toshiro

    2007-08-01

    Central sympathoexcitation is involved in the pathogenesis of salt-sensitive hypertension. We have suggested that oxidative stress in the brain modulates the sympathetic regulation of arterial pressure. Thus, we investigated whether oxidative stress could mediate central sympathoexcitation in salt-sensitive hypertension. Five- to 6-week-old male Dahl salt-sensitive rats and salt-resistant rats were fed with a normal (0.3%) or high- (8%) salt diet for 4 weeks. In urethane-anesthetized and artificially ventilated rats, arterial pressure, renal sympathetic nerve activity, and heart rate decreased in a dose-dependent fashion, when 20 or 40 micromol of tempol, a membrane-permeable superoxide dismutase mimetic, was infused into the lateral cerebral ventricle. The same degree of reduction was noted in salt-sensitive and salt-resistant rats without salt loading. Salt loading significantly increased central tempol-induced reductions in arterial pressure (-29.1+/-4.8% versus -10.6+/-3.3% at 40 micromol; P<0.01), sympathetic nerve activity (-18.7+/-2.0% versus -7.1+/-1.8%; P<0.01), and heart rate (-10.7+/-2.8% versus -2.0+/-0.7%; P<0.05) in salt-sensitive rats but not in salt-resistant rats. Intracerebroventricular diphenyleneiodonium, a reduced nicotinamide-adenine dinucleotide phosphate oxidase inhibitor, also elicited significantly greater reduction in each parameter in salt-loaded salt-sensitive rats. Moreover, salt loading increased reduced nicotinamide-adenine dinucleotide phosphate-dependent superoxide production in the hypothalamus in salt-sensitive rats but not in salt-resistant rats. In addition, reduced nicotinamide-adenine dinucleotide phosphate oxidase subunits p22(phox), p47(phox), and gp91(phox) mRNA expression significantly increased in the hypothalamus of salt-loaded salt-sensitive rats. In conclusion, in salt-sensitive hypertension, increased oxidative stress in the brain, possibly via activation of reduced nicotinamide-adenine dinucleotide phosphate oxidase

  11. 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.

  12. 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.

  13. Development of pressure-sensitive dosage forms with a core liquefying at body temperature.

    PubMed

    Wilde, Lisa; Bock, Mona; Wolf, Marieke; Glöckl, Gunnar; Garbacz, Grzegorz; Weitschies, Werner

    2014-04-01

    Pressure-sensitive dosage forms have been developed that are intended for pulsatile delivery of drugs to the proximal small intestine. The novel dosage forms are composed of insoluble shell and either a hard fat W32 or polyethylene glycol (PEG) 1000 core that are both liquidizing at body temperature. The release is triggered by predominant pressure waves such as contractions of the pylorus causing rupture of the shell and an immediate emptying of the liquefied filling containing the active ingredient. In consequence immediately after the trigger has been effective the total amount of the drug is intended to be available for absorption in the upper small intestine. Both core types were coated with a cellulose acetate film that creates a pressure-sensitive shell in which mechanical resistance is depending on the coating thickness. Results of the texture analysis confirmed a correlation between the polymer load of the coating and the mechanical resistance. The dissolution test performed under conditions of physiological meaningful mechanical stress showed that the drug release is triggered by pressure waves of ⩾300 mbar which are representing the maximal pressure occurring during the gastric emptying.

  14. 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

  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. 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.

  17. Enhancing the signal-to-noise ratio of pressure sensitive paint data by singular value decomposition

    NASA Astrophysics Data System (ADS)

    Pastuhoff, M.; Yorita, D.; Asai, K.; Alfredsson, P. H.

    2013-07-01

    When using pressure sensitive paint under unsteady conditions in low-speed applications, the signal-to-noise ratio is usually low and may hinder the proper evaluation of the acquired data. Here, we propose a new noise-filtering scheme that is based on singular value decomposition. As a test case, we evaluate the fluctuating pressure field due to unsteady vortex shedding on the side of a square cylinder. The proposed scheme resulted in a reduction of pixel noise of the order of two magnitudes which made it possible to obtain results regarding the spatial form of flow structures as well as the shedding frequency.

  18. 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

  19. 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.

  20. Electro-dry-adhesion.

    PubMed

    Krahn, Jeffrey; Menon, Carlo

    2012-03-27

    This work presents novel conductive bioinspired dry adhesives with mushroom caps that enable the use of a synergistic combination of electrostatic and van der Waals forces (electro-dry-adhesion). An increase in shear adhesion bond strength of up to 2046% on a wide range of materials is measured when a maximum electrical field of 36.4 V μm(-1) is applied. A suction effect, due to the shape of the dry adhesive fibers, on overall adhesion was not noted for electro-dry-adhesives when testing was performed at both atmospheric and reduced pressure. Utilization of electrostatics to apply a preloading force to dry adhesive fiber arrays allows increased adhesion even after electrostatic force generation has been halted by ensuring the close contact necessary for van der Waals forces to be effective. A comparison is made between self-preloading of the electro-dry-adhesives and the direct application of a normal preloading pressure resulting in nearly the same shear bond strength with an applied voltage of 3.33 kV on the same sample.

  1. Electro-dry-adhesion.

    PubMed

    Krahn, Jeffrey; Menon, Carlo

    2012-03-27

    This work presents novel conductive bioinspired dry adhesives with mushroom caps that enable the use of a synergistic combination of electrostatic and van der Waals forces (electro-dry-adhesion). An increase in shear adhesion bond strength of up to 2046% on a wide range of materials is measured when a maximum electrical field of 36.4 V μm(-1) is applied. A suction effect, due to the shape of the dry adhesive fibers, on overall adhesion was not noted for electro-dry-adhesives when testing was performed at both atmospheric and reduced pressure. Utilization of electrostatics to apply a preloading force to dry adhesive fiber arrays allows increased adhesion even after electrostatic force generation has been halted by ensuring the close contact necessary for van der Waals forces to be effective. A comparison is made between self-preloading of the electro-dry-adhesives and the direct application of a normal preloading pressure resulting in nearly the same shear bond strength with an applied voltage of 3.33 kV on the same sample. PMID:22397643

  2. 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

  3. 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.

  4. 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

  5. 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.

  6. Subambient pressure ionization with nanoelectrospray source and interface for improved sensitivity in mass spectrometry

    SciTech Connect

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

    2008-03-01

    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 reverse-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. Performance of the low pressure ESI source and interface 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 low pressure ESI source was used compared to a standard atmospheric pressure ESI source.

  7. 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.

  8. A Fiber Optic Sensor Sensitive To Normal Pressure And Shear Stress

    NASA Astrophysics Data System (ADS)

    Cuomo, Frank W.; Kidwell, Robert S.; Hu, Andong

    1986-11-01

    A fiber optic lever sensing technique that can be used to measure normal pressure as well as shear stresses is discussed. This method uses three unequal fibers combining small size and good sensitivity. Static measurements appear to confirm the theoretical models predicted by geometrical optics and dynamic tests performed at frequencies up to 10 kHz indicate a flat response within this frequency range. These sensors are intended for use in a low speed wind tunnel environment.

  9. Removal of polychlorinated biphenyls from capacitors and pressure-sensitive paper by vacuum thermal recycling.

    PubMed

    Ohbayashi, Hiroshi; Hosomi, Masaaki; Kanbe, Hiromi; Melber, Albrecht; Bruckamp, Joerg

    2002-01-01

    This paper describes a new vacuum thermal recycling (VTR) method for treating discarded polychlorinated biphenyls (PCB)-contaminated capacitors and pressure-sensitive paper. Based on results demonstrating an exceptionally high PCB separation efficiency and recovery ratio from capacitors containing high-concentration PCBs, i.e. > 99.9%, respectively, the presented VTR method is verified to effectively remove PCBs. In addition, associated safety aspects of the employed procedure were confirmed.

  10. Blood pressure and heart rate variability and baroreflex sensitivity before and after brain death

    PubMed Central

    Conci, F; Di, R; Castiglioni, P

    2001-01-01

    OBJECTIVES—To evaluate spontaneous blood pressure and heart rate variability and spontaneous baroreflex sensitivity before and after brain death.
METHODS—Spontaneous variability of arterial blood pressure and heart rate—estimated by power spectra of systolic (SBP) and diastolic blood pressure (DBP) and pulse interval (PI)—and spontaneous baroreflex sensitivity (BRS)—estimated by the alpha index and the sequence technique—were evaluated in 11 patients twice: shortly before and 1 hour after the onset of brain death.
RESULTS—Significant spectral changes occurred after brain death: a general power reduction in PI spectra; a shift of SBP, DBP and PI powers toward the lower frequencies, resulting in a greater slope of the "1/f" spectral trends; and a marked reduction of SBP and DBP powers (-93%) and of SBP-PI coherence (−63%) at 0.1Hz. The estimated average BRS was relatively high before brain death (around 11 ms/mm Hg), and fell close to 0 or even was not detectable at all after brain death.
CONCLUSIONS—Parameters describing spontaneous blood pressure and heart rate variability and indexes reflecting the baroreflex function, which were relatively normal up to a few hours before brain death, underwent marked changes with the onset of brain death. All the changes found are likely to reflect the cessation of activity of the cardiovascular brain stem centres. These findings indicate that techniques of blood pressure and heart rate spectral analysis and of dynamic assessment of baroreflex sensitivity may be useful to complement the diagnosis of brain stem death.

 PMID:11606674

  11. 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

  12. 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.

  13. Preparation of an adhesive in emulsion for maxillofacial prosthetic.

    PubMed

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

    2010-10-13

    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.

  14. 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

  15. Luminophore application study of polymer-ceramic pressure-sensitive paint.

    PubMed

    Sakaue, Hirotaka; Hayashi, Tatsunori; Ishikawa, Hitoshi

    2013-05-29

    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.

  16. 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.

  17. 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

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    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.

  19. Improving liquid chromatography-mass spectrometry sensitivity using a subambient pressure ionization with nanoelectrospray (SPIN) interface

    SciTech Connect

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

    2011-04-22

    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 5-12-fold improvement in sensitivity relative to a conventional atmospheric pressure nanoelectrospray ionization (ESI) source was obtained for detected peptides.

  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. Referenced dual pressure- and temperature-sensitive paint for digital color camera read out.

    PubMed

    Fischer, Lorenz H; Karakus, Cüneyt; Meier, Robert J; Risch, Nikolaus; Wolfbeis, Otto S; Holder, Elisabeth; Schäferling, Michael

    2012-12-01

    The first fluorescent material for the referenced simultaneous RGB (red green blue) imaging of barometric pressure (oxygen partial pressure) and temperature is presented. This sensitive coating consists of two platinum(II) complexes as indicators and a reference dye, each of which is incorporated in appropriate polymer nanoparticles. These particles are dispersed in a polyurethane hydrogel and spread onto a solid support. The emission of the (oxygen) pressure indicator, PtTFPP, matches the red channel of a RGB color camera, whilst the emission of the temperature indicator [Pt(II) (Br-thq)(acac)] matches the green channel. The reference dye, 9,10-diphenylanthracene, emits in the blue channel. In contrast to other dual-sensitive materials, this new coating allows for the simultaneous imaging of both indicator signals, as well as the reference signal, in one RGB color picture without having to separate the signals with additional optical filters. All of these dyes are excitable with a 405 nm light-emitting diode (LED). With this new composite material, barometric pressure can be determined with a resolution of 22 mbar; the temperature can be determined with a resolution of 4.3 °C.

  2. Magnitude of Morning Surge in Blood Pressure Is Associated with Sympathetic but Not Cardiac Baroreflex Sensitivity.

    PubMed

    Johnson, Aaron W; Hissen, Sarah L; Macefield, Vaughan G; Brown, Rachael; Taylor, Chloe E

    2016-01-01

    The ability of the arterial baroreflex to regulate blood pressure may influence the magnitude of the morning surge in blood pressure (MSBP). The aim was to investigate the relationships between sympathetic and cardiac baroreflex sensitivity (BRS) and the morning surge. Twenty-four hour ambulatory blood pressure was recorded in 14 young individuals. The morning surge was defined via the pre-awakening method, which is calculated as the difference between mean blood pressure values 2 h before and 2 h after rising from sleep. The mean systolic morning surge, diastolic morning surge, and morning surge in mean arterial pressures were 15 ± 2, 13 ± 1, and 11 ± 1 mmHg, respectively. During the laboratory protocol, continuous measurements of blood pressure, heart rate, and muscle sympathetic nerve activity (MSNA) were made over a 10-min period of rest. Sympathetic BRS was quantified by plotting MSNA burst incidence against diastolic pressure (sympathetic BRSinc), and by plotting total MSNA against diastolic pressure (sympathetic BRStotal). Cardiac BRS was quantified using the sequence method. The mean values for sympathetic BRSinc, sympathetic BRStotal and cardiac BRS were -1.26 ± 0.26 bursts/100 hb/mmHg, -1.60 ± 0.37 AU/beat/mmHg, and 13.1 ± 1.5 ms/mmHg respectively. Significant relationships were identified between sympathetic BRSinc and the diastolic morning surge (r = 0.62, p = 0.02) and the morning surge in mean arterial pressure (r = 0.57, p = 0.03). Low sympathetic BRS was associated with a larger morning surge in mean arterial and diastolic blood pressure. Trends for relationships were identified between sympathetic BRStotal and the diastolic morning surge (r = 0.52, p = 0.066) and the morning surge in mean arterial pressure (r = 0.48, p = 0.095) but these did not reach significance. There were no significant relationships between cardiac BRS and the morning surge. These findings indicate that the ability of the baroreflex to buffer increases in blood pressure

  3. Magnitude of Morning Surge in Blood Pressure Is Associated with Sympathetic but Not Cardiac Baroreflex Sensitivity

    PubMed Central

    Johnson, Aaron W.; Hissen, Sarah L.; Macefield, Vaughan G.; Brown, Rachael; Taylor, Chloe E.

    2016-01-01

    The ability of the arterial baroreflex to regulate blood pressure may influence the magnitude of the morning surge in blood pressure (MSBP). The aim was to investigate the relationships between sympathetic and cardiac baroreflex sensitivity (BRS) and the morning surge. Twenty-four hour ambulatory blood pressure was recorded in 14 young individuals. The morning surge was defined via the pre-awakening method, which is calculated as the difference between mean blood pressure values 2 h before and 2 h after rising from sleep. The mean systolic morning surge, diastolic morning surge, and morning surge in mean arterial pressures were 15 ± 2, 13 ± 1, and 11 ± 1 mmHg, respectively. During the laboratory protocol, continuous measurements of blood pressure, heart rate, and muscle sympathetic nerve activity (MSNA) were made over a 10-min period of rest. Sympathetic BRS was quantified by plotting MSNA burst incidence against diastolic pressure (sympathetic BRSinc), and by plotting total MSNA against diastolic pressure (sympathetic BRStotal). Cardiac BRS was quantified using the sequence method. The mean values for sympathetic BRSinc, sympathetic BRStotal and cardiac BRS were −1.26 ± 0.26 bursts/100 hb/mmHg, −1.60 ± 0.37 AU/beat/mmHg, and 13.1 ± 1.5 ms/mmHg respectively. Significant relationships were identified between sympathetic BRSinc and the diastolic morning surge (r = 0.62, p = 0.02) and the morning surge in mean arterial pressure (r = 0.57, p = 0.03). Low sympathetic BRS was associated with a larger morning surge in mean arterial and diastolic blood pressure. Trends for relationships were identified between sympathetic BRStotal and the diastolic morning surge (r = 0.52, p = 0.066) and the morning surge in mean arterial pressure (r = 0.48, p = 0.095) but these did not reach significance. There were no significant relationships between cardiac BRS and the morning surge. These findings indicate that the ability of the baroreflex to buffer increases in blood

  4. Magnitude of Morning Surge in Blood Pressure Is Associated with Sympathetic but Not Cardiac Baroreflex Sensitivity

    PubMed Central

    Johnson, Aaron W.; Hissen, Sarah L.; Macefield, Vaughan G.; Brown, Rachael; Taylor, Chloe E.

    2016-01-01

    The ability of the arterial baroreflex to regulate blood pressure may influence the magnitude of the morning surge in blood pressure (MSBP). The aim was to investigate the relationships between sympathetic and cardiac baroreflex sensitivity (BRS) and the morning surge. Twenty-four hour ambulatory blood pressure was recorded in 14 young individuals. The morning surge was defined via the pre-awakening method, which is calculated as the difference between mean blood pressure values 2 h before and 2 h after rising from sleep. The mean systolic morning surge, diastolic morning surge, and morning surge in mean arterial pressures were 15 ± 2, 13 ± 1, and 11 ± 1 mmHg, respectively. During the laboratory protocol, continuous measurements of blood pressure, heart rate, and muscle sympathetic nerve activity (MSNA) were made over a 10-min period of rest. Sympathetic BRS was quantified by plotting MSNA burst incidence against diastolic pressure (sympathetic BRSinc), and by plotting total MSNA against diastolic pressure (sympathetic BRStotal). Cardiac BRS was quantified using the sequence method. The mean values for sympathetic BRSinc, sympathetic BRStotal and cardiac BRS were −1.26 ± 0.26 bursts/100 hb/mmHg, −1.60 ± 0.37 AU/beat/mmHg, and 13.1 ± 1.5 ms/mmHg respectively. Significant relationships were identified between sympathetic BRSinc and the diastolic morning surge (r = 0.62, p = 0.02) and the morning surge in mean arterial pressure (r = 0.57, p = 0.03). Low sympathetic BRS was associated with a larger morning surge in mean arterial and diastolic blood pressure. Trends for relationships were identified between sympathetic BRStotal and the diastolic morning surge (r = 0.52, p = 0.066) and the morning surge in mean arterial pressure (r = 0.48, p = 0.095) but these did not reach significance. There were no significant relationships between cardiac BRS and the morning surge. These findings indicate that the ability of the baroreflex to buffer increases in blood

  5. Assessment of baroreflex sensitivity by continuous noninvasive monitoring of peripheral and central aortic pressure.

    PubMed

    Kouchaki, Zahra; Butlin, Mark; Qasem, Ahmed; Avolio, Alberto P

    2014-01-01

    Noninvasive assessment of baroreceptor sensitivity (BRS) facilitates clinical investigation of autonomic function. The spontaneous sequence method estimates BRS using the continuous measurement of arterial pressure in the finger. Since the baroreceptors are centrally located (aortic arch, carotid arteries), this study assessed the use of a continuous aortic pressure signal derived from the peripheral pressure pulse to compute the BRS from changes in systolic pressure (SBP) and pulse interval (PI). BRS computed from central aortic (cBRS) and peripheral pressure (pBRS) was calculated in 12 healthy subjects (25-62 years, 7 females). The difference between pBRS and cBRS was calculated for four levels of pulse lags between changes in SBP and PI. For each lag and for the pooled data for all lags, cBRS was significantly correlated with pBRS (r(2)=0.82). The within subject difference ranged from -41.2% to 59.2%. This difference was not related to age, gender of hemodynamic parameters (systolic or diastolic pressure, heart rate, aortic pulse wave velocity). However 18.2% of the variance was due to the difference in the number of spontaneous pulse sequences used to determine values of cBRS and pBRS. The differences between pBRS and cBRS are in the range of values of BRS as those found, in other studies, to discriminate between patient groups with different levels of autonomic function. Findings of this study suggest that, given the heart rate dependent amplification of the arterial pressure pulse between the central aorta and the peripheral limbs, BRS determined from central aortic pressure derived from the peripheral pulse may provide an improved method for noninvasive assessment of baroreceptor function.

  6. 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.

  7. 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

  8. Blood Pressure and Amiloride-Sensitive Sodium Channels in Vascular and Renal Cells

    PubMed Central

    Warnock, David G.; Kusche-Vihrog, Kristina; Tarjus, Antoine; Sheng, Shaohu; Oberleithner, Hans; Kleyman, Thomas R.; Jaisser, Frederic

    2014-01-01

    This review is focused on the expression and regulation of amiloride-sensitive sodium channels in the epithelial cells of the aldosterone-sensitive distal nephron (ENaC) and amiloride-sensitive sodium channel activity in vascular endothelial and smooth muscle cells. Guyton’s hypothesis stated that blood pressure control is critically dependent on vascular tone and fluid handling by the kidney. With the study of Mendelian forms of hypertension and their corresponding transgenic mouse models, the main components of the aldosterone- and angiotensin-dependent sodium transporters have been identified over the past 20 years. Proteolytic processing of the ENaC external domain, and inhibition by increased sodium concentrations are important features of the ENaC complexes expressed in the distal nephron. In contrast, amiloride-sensitive sodium channels expressed in the vascular system are activated by increased external sodium concentrations, resulting in changes in the mechanical properties and function of endothelial cells. Mechano-sensitivity and shear stress affect both epithelial and vascular sodium channel activity. The synergistic effects and complementary regulation of the epithelial and vascular systems are consistent with the Guytonian model of volume and blood pressure regulation, and may reflect sequential evolution of the two systems. The integration of vascular tone, renal perfusion and regulation of renal sodium reabsorption is the central underpinning of the Guytonian model. We summarize the recent evidence in this review that describes the central role of amiloride-sensitive sodium channels in the efferent (e.g., vascular) and afferent (e.g., epithelial) arms of this homeostatic system. PMID:24419567

  9. Magnetic field switchable dry adhesives.

    PubMed

    Krahn, Jeffrey; Bovero, Enrico; Menon, Carlo

    2015-02-01

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

  10. 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.

  11. Development of a pressure-sensitive glyceryl tristearate capsule filled with a drug-containing hydrogel.

    PubMed

    Wilde, Lisa; Bock, Mona; Glöckl, Gunnar; Garbacz, Grzegorz; Weitschies, Werner

    2014-01-30

    The purpose of this work was to develop a new pressure-sensitive dosage form that breaks and releases its content in a fasted stomach at the predominant pressure at the pylorus. The content of the dosage form should be liquid so that the active pharmaceutical ingredient quickly reaches maximum absorption in the upper small intestine. For this purpose glyceryl tristearate capsules were developed, consisting of an extremely brittle shell, with a crushing behavior that can be controlled by modification of the shell thickness. The capsules were filled with a hydroxyethyl cellulose gel containing paracetamol. Dissolution testing using USP apparatus 2, performed for simulating the resting time in the stomach, did not show any release. Studies using a texture analyser showed a correlation between the glyceryl tristearate filling volume and the necessary force to break the capsule. Physiological conditions in dissolution testing, such as movement, pressure and discontinuous medium contact, were set in a stress test device and showed that the dosage forms did not break and release its pharmaceutical ingredient until a pressure of 300 mbar was applied which served as a threshold limit for physiological pressure occurring during gastric emptying of large solids. PMID:24333906

  12. The sensitivity of the burst performance of impact damaged pressure vessels to material strength properties

    NASA Astrophysics Data System (ADS)

    Lasn, K.; Vedvik, N. P.; Echtermeyer, A. T.

    2016-07-01

    This numerical study is carried out to improve the understanding of short-term residual strength of impacted composite pressure vessels. The relationship between the impact, created damage and residual strength is predicted by finite element (FE) analysis. The burst predictions depend largely on the strength properties used in the material models. However, it is typically not possible to measure all laminate properties on filament wound structures. Reasonable testing efforts are concentrated on critical properties, while obtaining other less sensitive parameters from e.g. literature. A parametric FE model is hereby employed to identify the critical strength properties, focusing on the cylindrical section of the pressure vessel. The model simulates an impactor strike on an empty vessel, which is subsequently pressurized until burst. Monte Carlo Simulations (MCS) are employed to investigate the correlations between strength related material parameters and the burst pressure. The simulations indicate the fracture toughness of the composite, hoop layer tensile strength and the yield stress of the PE liner as the most influential parameters for current vessel and impact configurations. In addition, the conservative variation in strength parameters is shown to have a rather moderate effect (COV ca. 7%) on residual burst pressures.

  13. 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.

  14. Pressure Pain Sensitivity in Patients With Suspected Opioid-Induced Hyperalgesia

    PubMed Central

    Wasserman, Ronald A.; Hassett, Afton L.; Harte, Steven E.; Goesling, Jenna; Malinoff, Herbert L.; Berland, Daniel W.; Zollars, Jennifer; Moser, Stephanie E.; Brummett, Chad M.

    2015-01-01

    Background and Objectives This study was designed to test whether a brief quantitative sensory testing (QST) assessment could be used to detect hyperalgesia in patients with suspected opioid-induced hyperalgesia. Methods Twenty patients on long-term opioid therapy with suspected opioid-induced hyperalgesia were recruited along with and 20 healthy controls. Pressure pain threshold, Pain50, a measure of intermediate suprathreshold pressure pain sensitivity, and tolerance levels, were evaluated. As a secondary outcome, changes in pressure pain sensitivity following intravenous administration of placebo (saline) and fentanyl (1.5 μg/kg) were assessed. Results There were no significant differences in pain measures between healthy controls and patients. However, there was an association between higher doses of opioids and having a lower pain tolerance (r= -0.46, P=0.041) and lower Pain50 (r=-0.46, P = 0.044), which was consistent with the hypothesis. Patients on >100 mg oral morphine equivalents (OME) displayed decreased pressure pain tolerance compared to patients taking <100 mg OME (P = 0.042). In addition, male patients showed a hyperalgesic response to fentanyl administration, which was significant for the Pain50 measure (P=0.002). Conclusions Whereas there were no differences between patients suspected of having opioid-induced hyperalgesia and the healthy controls, the finding that higher doses of opioids were associated with more sensitivity suggests that dose might be an important factor in the development of hyperalgesia. In addition, male patients demonstrated a hyperalgesic response after a bolus of fentanyl. Future studies are needed to develop better diagnostics for detecting hyperalgesia in the clinical setting. PMID:26469365

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Quantitative visualization of asymmetric gas flow in constricted microchannels by using pressure-sensitive paint

    NASA Astrophysics Data System (ADS)

    Huang, Chih-Yung; Chen, Ying-Hsuan; Wan, Shaw-An; Wang, Yu-Chuan

    2016-10-01

    Asymmetric flow in constricted microchannel devices was quantitatively investigated using a pressure-sensitive paint (PSP) technique. For microchannel devices with constriction ratios of 2 : 1 and 5 : 1, detailed pressure maps for the region around the constriction structure were obtained and enabled visualization of the flow field. Symmetric flow was observed in the microchannel device with a constriction ratio of 2 : 1 at the Reynolds number range 2-165. In the microchannel with a constriction ratio of 5 : 1, a deflected flow pattern was clearly identified from PSP measurements at Reynolds numbers exceeding 107. Furthermore, PSP measurements showed a pressure difference of up to 2.5 kPa between the two lateral locations corresponding to y  =  ±0.15 W (W is the microchannel width) downstream of the constriction at a Reynolds number of 279. The pressure difference resulted from asymmetric bifurcation of the flow.

  2. Identification of the resonant modes in supersonic impinging jets using fast response pressure sensitive paint

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    High speed impinging jets have been the focus of several studies owing to their practical application and resonance dominated flow-field. The current study utilizes fast-response pressure sensitive paint (PSP) to examine the jet instability modes of a Mach 1.5 normally impinging jet. These modes are associated with high amplitude, discrete peaks in the power spectra and can be identified as having either axisymmetric or azimuthal modes. Phase-averaged images are acquired at various nozzle to plate spacings and at frequencies of several kHz. Using an unsteady pressure transducer on the impingement surface as a reference signal, a high speed LED with a wavelength of 460 nm is used to illuminate the PSP. The paint fluorescence is then recorded with a CCD camera. The average pressure distribution is removed from the acquired images, resulting in the phase-averaged unsteady pressure distribution. The processed images reveal axisymmetric modes for all nozzle to plate spacings tested except at 4 jet diameters. At this spacing, three distinct resonant modes are identified.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Electro-Luminescence based Pressure-Sensitive Paint System for Unsteady Flow Field Measurements

    NASA Astrophysics Data System (ADS)

    Iijima, Yoshimi; Sakaue, Hirotaka

    2011-11-01

    Electro-luminescence (EL) based pressure-sensitive paint (PSP) system is developed for capturing unsteady flow fields. It has advantages in uniform distribution in the illumination without remotely apply the illumination source from the testing object. The resultant system can be applied directly onto a testing object surface. It consists of an inorganic EL and a PSP. The EL emits blue illumination uniformly applied onto the PSP layer. Because of a sheet illumination, the EL gives uniform distribution, while a point illumination gives a spot in illumination. The PSP is developed to provide a fast response to a change in pressure. It uses a porous particle and a polymer to create porous-polymer PSP. The response time characterization of the developed system is included in the presentation. The developed system is applied to an unsteady flow field, such as a sound field in a resonance tube.

  8. Motion-deblurred, fast-response pressure-sensitive paint on a rotor in forward flight

    NASA Astrophysics Data System (ADS)

    Juliano, Thomas J.; Disotell, Kevin J.; Gregory, James W.; Crafton, Jim; Fonov, Sergey

    2012-04-01

    A pressure-sensitive paint (PSP) system capable of measuring the global, unsteady pressure distribution on a rotating surface without resorting to phase averaging is applied to a two-bladed model propeller in edgewise freestream flow. A gated lifetime-based technique captures the paint luminescence after a single pulse of high-energy laser excitation, yielding a signal-to-noise ratio sufficient to avoid image averaging. The selection of a porous polymer/ceramic matrix base with platinum tetra(pentafluorophenyl) porphyrin (PtTFPP) as the luminophore afforded high frequency response and pressure sensitivity, but the long lifetime of PtTFPP caused blurring in the long-exposure image of the rotating blade. An approach to deblurring based on the lifetime of the paint and surface motion is described and validated by results obtained from a disc of 17.8 cm diameter spinning at 70 Hz. An infrared camera recorded wind-on and -off temperature maps to provide a temperature correction for the PSP. The single-shot PSP technique with motion deblurring and temperature correction is then applied to a vertically mounted model propeller with a 25.4 cm diameter and 10.2 cm pitch. Surface pressure maps for the advancing and retreating blades are presented for a spin rate of 70 Hz and advance ratio of 0.3. The higher suction peak and other features on the advancing blade due to its larger effective velocity are detected by the paint system, while the retreating blade shows a qualitatively different distribution.

  9. Sensitizing effects of NO{sub x} on CH{sub 4} oxidation at high pressure

    SciTech Connect

    Rasmussen, Christian Lund; Rasmussen, Anja Egede; Glarborg, Peter

    2008-08-15

    The CH{sub 4}/O{sub 2}/NO{sub x} system is investigated in a laboratory-scale high pressure laminar flow reactor with the purpose of elucidating the sensitizing effects of NO{sub x} on CH{sub 4} oxidation at high pressures and medium temperatures. Experiments are conducted at 100, 50, and 20 bar, 600-900 K, and stoichiometric ratios ranging from highly reducing to oxidizing conditions. The experimental results are interpreted in terms of a detailed kinetic model drawn from previous work of the authors, including an updated reaction subset for the direct interactions of NO{sub x} and C{sub 1-2} hydrocarbon species relevant to the investigated conditions. The results reveal a significant decrease in the initiation temperature upon addition of NO{sub x}. A similar effect is observed with increasing pressure. The sensitizing effect of NO{sub x} is related to the hydrocarbon chain-propagating NO/NO{sub 2} cycle operated by NO{sub 2}+CH{sub 3}{r_reversible}NO+CH{sub 3}O and NO+CH{sub 3}OO{r_reversible}NO{sub 2}+CH{sub 3}O as well as the formation of chain-initiating OH radicals from interactions between NO/NO{sub 2} and the H/O radical pool. At low temperatures, reactions between NO/NO{sub 2} and CH{sub 3}O/CH{sub 2}O also gain importance. The results indicate a considerable intermediate formation of nitromethane (CH{sub 3}NO{sub 2}) as a characteristic high-pressure phenomenon. The formation of CH{sub 3}NO{sub 2} represents an inactivation of NO{sub x}, which may result in a temporary reduction of the overall hydrocarbon conversion rate. (author)

  10. The Effect of Gaseous Additives on Dynamic Pressure Output and Ignition Sensitivity of Nanothermites

    NASA Astrophysics Data System (ADS)

    Puszynski, Jan; Doorenbos, Zac; Walters, Ian; Redner, Paul; Kapoor, Deepak; Swiatkiewicz, Jacek

    2011-06-01

    This contribution addresses important combustion characteristics of nanothermite systems. In this research the following nanothermites were investigated: a) Al-Bi2O3, b)Al-Fe2O3 and c)Al-Bi2O3-Fe2O3. The effect of various gasifying additives (such as nitrocellulose (NC) and cellulose acetate butyrate (CAB)) as well as reactant stoichiometry, reactant particle size and shape on processability, ignition delay time and dynamic pressure outputs at different locations in a combustion chamber will be presented. In addition, this contribution will report electrostatic and friction sensitivities of standard and modified nanothermites.

  11. High sensitivity nuclear magnetic resonance probe for anvil cell pressure experiments.

    PubMed

    Haase, Jürgen; Goh, Swee K; Meissner, Thomas; Alireza, Patricia L; Rybicki, Damian

    2009-07-01

    While the highest pressures can be achieved with diamond anvil cells, limited sample size and anvil geometry have hampered their application in nuclear magnetic resonance (NMR) experiments due to weak signal-to-noise. Here we report a new probe design that is based on having the resonant radio frequency coil that encloses the sample within the anvil cell inside the gasket hole. This increases the filling factor tremendously and results in greatly enhanced NMR sensitivity. The setup is described together with room temperature Na and Al NMR experiments. PMID:19655963

  12. Optical measurement of acoustic pressure amplitudes-at the sensitivity limits of Rayleigh scattering.

    PubMed

    Rausch, Anne; Fischer, André; Kings, Nancy; Bake, Friedrich; Roehle, Ingo

    2012-07-01

    Rayleigh scattering is a measurement technique applicable for the determination of density distributions in various technical or natural flows. The current sensitivity limits of the Rayleigh scattering technique were investigated experimentally. It is shown that it is possible to measure density oscillations caused by acoustic pressure oscillations noninvasively and directly. Acoustical standing waves in a rectangular duct were investigated using Rayleigh scattering and compared to microphone measurements. The comparison showed a sensitivity of the Rayleigh scattering technique of 75 Pa (7·10(-4) kg/m(3)) and a precision of 14 Pa (1·10(-4) kg/m(3)). Therefore, it was also shown that Rayleigh scattering is applicable for acoustic measurements. PMID:22743495

  13. 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.

  14. 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

  15. Immune suppression prevents renal damage and dysfunction and reduces arterial pressure in salt-sensitive hypertension.

    PubMed

    Tian, N; Gu, J-W; Jordan, S; Rose, R A; Hughson, M D; Manning, R D

    2007-02-01

    The goal of this study was to test the hypothesis that renal infiltration of immune cells in Dahl S rats on increased dietary sodium intake contributes to the progression of renal damage, decreases in renal hemodynamics, and development of hypertension. We specifically studied whether anti-immune therapy, using mycophenolate mofetil (MMF), could help prevent increases in renal NF-kappaB activation, renal infiltration of monocytes/macrophages, renal damage, decreases in glomerular filtration rate (GFR) and renal plasma flow, and increases in arterial pressure. Seventy-four 7-to 8-wk-old Dahl S, Rapp strain rats were maintained on an 8% Na, 8% Na + MMF (20 mg.kg(-1).day(-1)), 0.3% Na, or 0.3% Na + MMF diet for 5 wk. Arterial and venous catheters were implanted at day 21. By day 35, renal NF-kappaB in 8% Na rats was 47% higher than in 0.3% Na rats and renal NF-kappaB was 41% lower in 8% Na + MMF rats compared with the 8% Na group. MMF treatment significantly decreased renal monocyte/macrophage infiltration and renal damage and increased GFR and renal plasma flow. In high-NA Dahl S rats mean arterial pressure increased to 182 +/- 5 mmHg, and MMF reduced this arterial pressure to 124 +/- 3 mmHg. In summary, in Dahl S rats on high sodium intake, treatment with MMF decreases renal NF-kappaB and renal monocyte/macrophage infiltration and improves renal function, lessens renal injury, and decreases arterial pressure. This suggests that renal infiltration of immune cells is associated with increased arterial pressure and renal damage and decreasing GFR and renal plasma flow in Dahl salt-sensitive hypertension.

  16. 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.

  17. 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.

  18. 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.

  19. [Thermal infrared spectral variation and sensitive waveband of quartzy sandstone under pressure].

    PubMed

    Liu, Shan-jun; Wu, Li-xin; Feng, Zhe; Xu, Zhong-yin

    2012-01-01

    In the present paper the thermal infrared spectral variation of quartz sandstone under uniaxial compression was detected by a spectroradiometer to study the sensitively responding waveband of infrared radiation excited by the pressure. The experimental result shows that the infrared spectrum varies with the load, and the variation feature is different in different wavebands. The infrared radiation intensity increases with the increase in the load within the waveband 8.0-11.5 microm (specially in 8.6-9.1 microm), and there is a quadratic correlation between them, meanwhile the signal-to-noise ratio of spectrum radiation is also higher in the waveband. But in other wavebands the correlation is worse and the signal-to-noise is also lower. This indicates that the waveband 8.0-11.5 microm is the sensitive waveband of infrared radiation to the pressure, and it is also the superior waveband for infrared remote sensing monitoring the stress and catastrophe of rock. The optimum waveband is 8.6-9.1 microm.

  20. 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

  1. Development and Characterization of Pressure-Sensitive Microbeads for Simultaneous Barometry and Velocimetry for Fluid Dynamic Applications

    NASA Astrophysics Data System (ADS)

    Lewis, Daniel Raiken

    The use of luminescent dyes to measure pressures and temperatures on surfaces using Pressure Sensitive Paint (PSP) and Temperature-Sensitive Paint (TSP) is a well-established methodology. New technology has allowed for microbeads to be loaded with pressure and/or temperature sensitive dyes. These microbeads can be seeded into flow fields in order to measure the pressure and/or temperature fields in the fluid flow. In addition, the microbeads act as tracer particles to the fluid velocity and therefore, standard PIV techniques can be applied to quantify the velocity of the flow simultaneously with the pressure and/or temperature measurement. Existing studies have investigated the use of polystyrene microbeads for simultaneous flow barometry and velocimetry yet the polystyrene microbeads have a slow response time to changing pressures, making them incapable of resolving accurate pressures in fast flow applications such as wind tunnels. In this contribution, silicon dioxide and oxide-based multi-dye microbeads were characterized and found to have much faster response times than polystyrene-based microbeads. The pressure response times and sensitivity of these microbeads were tested to determine the most viable candidate for future unsteady applications. It will also be shown that the intensity-based approach applied to these microbeads coated on a glass slide can be used to accurately measure pressure with a significantly high measure of precision and low pressure uncertainties down to 106Pa. Finally, this paper will demonstrate the feasibility of using aerosolized pressure-sensitive microbeads for simultaneous barometry and velocimetry for fluid dynamic applications.

  2. 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.

  3. 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).

  4. Aortic and Carotid Arterial Stiffness and Epigenetic Regulator Gene Expression Changes Precede Blood Pressure Rise in Stroke-Prone Dahl Salt-Sensitive Hypertensive Rats

    PubMed Central

    Herrera, Victoria L.; Decano, Julius L.; Giordano, Nicholas; Moran, Ann Marie; Ruiz-Opazo, Nelson

    2014-01-01

    Multiple clinical studies show that arterial stiffness, measured as pulse wave velocity (PWV), precedes hypertension and is an independent predictor of hypertension end organ diseases including stroke, cardiovascular disease and chronic kidney disease. Risk factor studies for arterial stiffness implicate age, hypertension and sodium. However, causal mechanisms linking risk factor to arterial stiffness remain to be elucidated. Here, we studied the causal relationship of arterial stiffness and hypertension in the Na-induced, stroke-prone Dahl salt-sensitive (S) hypertensive rat model, and analyzed putative molecular mechanisms. Stroke-prone and non-stroke-prone male and female rats were studied at 3- and 6-weeks of age for arterial stiffness (PWV, strain), blood pressure, vessel wall histology, and gene expression changes. Studies showed that increased left carotid and aortic arterial stiffness preceded hypertension, pulse pressure widening, and structural wall changes at the 6-week time-point. Instead, differential gene induction was detected implicating molecular-functional changes in extracellular matrix (ECM) structural constituents, modifiers, cell adhesion, and matricellular proteins, as well as in endothelial function, apoptosis balance, and epigenetic regulators. Immunostaining testing histone modifiers Ep300, HDAC3, and PRMT5 levels confirmed carotid artery-upregulation in all three layers: endothelial, smooth muscle and adventitial cells. Our study recapitulates observations in humans that given salt-sensitivity, increased Na-intake induced arterial stiffness before hypertension, increased pulse pressure, and structural vessel wall changes. Differential gene expression changes associated with arterial stiffness suggest a molecular mechanism linking sodium to full-vessel wall response affecting gene-networks involved in vascular ECM structure-function, apoptosis balance, and epigenetic regulation. PMID:25229245

  5. 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...

  6. 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

  7. 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%.

  8. Development and validation of a sensitive, high-throughput bioassay for the adhesion of radiolabeled E. coli to uroepithelial cells in vitro.

    PubMed

    Mathison, Bridget D; Kimble, Lindsey L; Kaspar, Kerrie L; Khoo, Christina; Chew, Boon P

    2013-09-27

    Vaccinium macrocarpon (cranberry) products have been used to prevent uropathogenic Escherichia (E.) coli adherence to uroepithelial cells (UEC) and may help reduce risk of urinary tract infection. Reported herein are the development and validation of an assay to assess antiadhesion activity of V. macrocarpon extracts and human urine. P-fimbriated E. coli (CFT073) was labeled with ³H-uridine, then co-incubated with HTB-4 UEC at a 400:1 ratio. V. macrocarpon extracts (0-17 mg proanthocyanidins/mL) were added to ³H-labeled E. coli before co-incubating with UEC. The assay yielded a sensitive inhibition curve: the lower limit of detection and half-maximal inhibitory concentration were 0.43 and 1.59 mg proanthocyanidins/mL for V. macrocarpon extract CEP 55; intra- and interassay coefficients of variance were <10% and <15%, respectively. V. macrocarpon extract CEP 3283 showed identical adhesion inhibition. Serial dilutions of urine from human participants who consumed V. macrocarpon beverages showed a linear decrease in antiadhesion activity. Antiadhesion assays conducted with urine from a human intervention study also showed good agreement with results obtained using the hemagglutination assay. Therefore, a sensitive, high-throughput, biologically relevant antiadhesion assay using ³H-E. coli co-incubated with UEC is reported, which can be used for studying the action of V. macrocarpon bioactives.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Relationships between baroreceptor cardiac reflex sensitivity and cognitive performance: modulations by gender and blood pressure.

    PubMed

    Paso, Gustavo A Reyes Del; Mata, José Luis; Martín-Vázquez, María

    2012-01-01

    This study aimed at replicating and extending previous results on the association between baroreceptor reflex sensitivity (BRS) and cognitive performance. Thirty men and 31 women performed an arithmetic task. After adjusting for numerical aptitude and effort, no predictors of performance were found in men. In women, the relationships between BRS and parameters related to correct responses were modulated by blood pressure (BP). BRS was inversely associated with these parameters for participants with BP>1 SD above the mean, whereas the associations were positive in participants with BP<1 SD below the mean. Also for women, BRS was positively associated with number of errors during the task. These results suggest that the relation between BRS and performance varies as a function of the type of cognitive processes assessed and that the central nervous system effects of the baroreceptors on cognitive functioning are modulated by gender and BP.

  14. Ultra-sensitive flow measurement in individual nanopores through pressure--driven particle translocation.

    PubMed

    Gadaleta, Alessandro; Biance, Anne-Laure; Siria, Alessandro; Bocquet, Lyderic

    2015-05-01

    A challenge for the development of nanofluidics is to develop new instrumentation tools, able to probe the extremely small mass transport across individual nanochannels. Such tools are a prerequisite for the fundamental exploration of the breakdown of continuum transport in nanometric confinement. In this letter, we propose a novel method for the measurement of the hydrodynamic permeability of nanometric pores, by diverting the classical technique of Coulter counting to characterize a pressure-driven flow across an individual nanopore. Both the analysis of the translocation rate, as well as the detailed statistics of the dwell time of nanoparticles flowing across a single nanopore, allow us to evaluate the permeability of the system. We reach a sensitivity for the water flow down to a few femtoliters per second, which is more than two orders of magnitude better than state-of-the-art alternative methods.

  15. 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.

  16. 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.

  17. Feasibility for development of a nuclear reactor pressure vessel flaw distribution: Sensitivity analyses and NDE (nondestructive evaluation) capability

    SciTech Connect

    Rosinski, S.T. ); Kennedy, E.L.; Foulds, J.R. )

    1990-01-01

    Pressurized water reactor pressure vessels operate under US Nuclear Regulatory Commission (NRC) rules and regulatory guides that are intended to maintain a low probability of vessel failure. The NRC has also addressed neutron embrittlement of pressurized water reactor pressure vessels by imposing regulations on plant operation. Plants failing to meet the operating criteria specified by these rules and regulations are required, among other things, to analytically demonstrate fitness for service in order to continue safe operation. The initial flaw size or distribution of initial vessel flaws is a key input to the required vessel integrity analyses. A fracture mechanics sensitivity study was performed to quantify the effect of the assumed flaw distribution on the predicted vessel performance under a specified pressurized thermal shock transient and to determine the critical crack size. Results of the analysis indicate that vessel performance in terms of the estimated probability of failure is very sensitive to the assumed flaw distribution. 20 refs., 3 figs., 2 tabs.

  18. 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

  19. Groin dressing after cardiac catheterization. Comparison between light dressing with thin transparent tape (Tegaderm) and conventional tight/pressure dressing with an elastic adhesive bandage (Tensoplast).

    PubMed

    Boonbaichaiyapruck, S; Hutayanon, P; Chanthanamatta, P; Dumrongwatana, T; Intarayotha, N; Krisdee, V; Yamvong, S

    2001-12-01

    Post cardiac catheterization puncture site care is usually done with a tight pressure dressing by an elastic adhesive bandage (Tensoplast) due to the belief that it should prevent bleeding. The practice is uncomfortable to the patients. The authors compared a new way of dressing using light transparent tape (Tegaderm) to the conventional tight pressure one. 126 post coronary angiography patients were randomized to have their groins dressed either with Tensoplast or with Tegaderm. Patients ambulated 8 hours after the procedures. The groin was evaluated for pain, discomfort and bleeding complications. 49 per cent in the Tensoplast vs 26.9 per cent in the Tegaderm group experienced pain (p value of 0.01). 55.5 per cent in the Tensoplast group vs 11.1 per cent in the Tegaderm group reported discomfort. 4.7 per cent in the Tensoplast vs 1.6 per cent in the Tegaderm group developed bleeding or hematoma. Dressing of the puncture site after cardiac catheterization with Tegaderm was more comfortable than the conventional Tensoplast without any difference in bleeding complications.

  20. 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.

  1. Blood pressure and amiloride-sensitive sodium channels in vascular and renal cells.

    PubMed

    Warnock, David G; Kusche-Vihrog, Kristina; Tarjus, Antoine; Sheng, Shaohu; Oberleithner, Hans; Kleyman, Thomas R; Jaisser, Frederic

    2014-03-01

    Sodium transport in the distal nephron is mediated by epithelial sodium channel activity. Proteolytic processing of external domains and inhibition with increased sodium concentrations are important regulatory features of epithelial sodium channel complexes expressed in the distal nephron. By contrast, sodium channels expressed in the vascular system are activated by increased external sodium concentrations, which results in changes in the mechanical properties and function of endothelial cells. Mechanosensitivity and shear stress affect both epithelial and vascular sodium channel activity. Guyton's hypothesis stated that blood pressure control is critically dependent on vascular tone and fluid handling by the kidney. The synergistic effects, and complementary regulation, of the epithelial and vascular systems are consistent with the Guytonian model of volume and blood pressure regulation, and probably reflect sequential evolution of the two systems. The integration of vascular tone, renal perfusion and regulation of renal sodium reabsorption is the central underpinning of the Guytonian model. In this Review, we focus on the expression and regulation of sodium channels, and we outline the emerging evidence that describes the central role of amiloride-sensitive sodium channels in the efferent (vascular) and afferent (epithelial) arms of this homeostatic system.

  2. 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.

  3. 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

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

    PubMed Central

    2016-01-01

    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. 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

  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.

  7. 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.

  8. 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

  9. 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

  10. Inverse characterisation of frequency-dependent properties of adhesives

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  11. A gecko-inspired double-sided adhesive.

    PubMed

    Wang, Zhengzhi; Gu, Ping; Wu, Xiaoping

    2013-12-21

    Geckos' outstanding abilities to adhere to various surfaces are widely credited to the large actual contact areas of the fibrillar and hierarchical structures on their feet. These special features regulate the essential structural compliance for every attachment and thus provide robust yet reversible adhesions. Inspired by gecko's feet and our commonly used double-faced tape, we have successfully fabricated a gecko-inspired double-sided dry adhesive by using porous anodic alumina template assisted nano-wetting on a stiff polymer. It was determined that the obtained 2-sided structure showed largely decreased effective stiffness compared with its 1-sided counterpart, which favored better compliance and interfacial integrity. We also demonstrated that the repeatable double-sided adhesive improved the macroscopic normal and shear adhesion capacities over the widely-studied 1-side structure by ~50% and ~85%, respectively. By using the synthetic double-sided adhesive, the usage of traditional pressure-sensitive/chemical adhesives could be well avoided. Besides, the double-sided nanostructures showed great potential in finding new interesting properties and practical applications for the synthetic dry adhesives.

  12. Frictional and elastic energy in gecko adhesive detachment.

    PubMed

    Gravish, Nick; Wilkinson, Matt; Autumn, Kellar

    2008-03-01

    Geckos use millions of adhesive setae on their toes to climb vertical surfaces at speeds of over 1 m s(-1). Climbing presents a significant challenge for an adhesive since it requires both strong attachment and easy, rapid removal. Conventional pressure-sensitive adhesives are either strong and difficult to remove (e.g. duct tape) or weak and easy to remove (e.g. sticky notes). We discovered that the energy required to detach adhering tokay gecko setae (W(d)) is modulated by the angle (theta) of a linear path of detachment. Gecko setae resist detachment when dragged towards the animal during detachment (theta = 30 degrees ) requiring W(d) = 5.0+/-0.86(s.e.) J m(-2) to detach, largely due to frictional losses. This external frictional loss is analogous to viscous internal frictional losses during detachment of pressure-sensitive adhesives. We found that, remarkably, setae possess a built-in release mechanism. Setae acted as springs when loaded in tension during attachment and returned elastic energy when detached along the optimal path (theta=130 degrees ), resulting in W(d) = -0.8+/-0.12 J m(-2). The release of elastic energy from the setal shaft probably causes spontaneous release, suggesting that curved shafts may enable easy detachment in natural, and synthetic, gecko adhesives.

  13. Use of statistical design of experiments in the optimization of Ar-O2 low-pressure plasma treatment conditions of polydimethylsiloxane (PDMS) for increasing polarity and adhesion, and inhibiting hydrophobic recovery

    NASA Astrophysics Data System (ADS)

    Butrón-García, María Isabel; Jofre-Reche, José Antonio; Martín-Martínez, José Miguel

    2015-03-01

    Polydimethylsiloxane (PDMS) film was treated with RF low-pressure plasmas (LPPs) made of mixtures of oxygen and argon for increasing surface polarity, minimizing hydrophobic recovery (i.e. retard ageing) and increasing adhesion to acrylic adhesive tape for medical use. Statistical design of experiments has been used for determining the most influencing experimental parameters of the LPP treatment of PDMS. Water contact angle values (measured 24 h after treatment) and the O/C ratio obtained from XPS experiments were used as response variables. Working pressure was the most influencing parameter in LPP treatment of PDMS, and the duration of the treatment, the power and the oxygen-argon mixture composition determined noticeably its effectiveness. The optimal surface properties in PDMS and inhibited hydrophobic recovery were achieved by treatment with 93 vol% oxygen + 7 vol% argon LLP at low working pressure (300 mTorr), low power (25 W) and long duration of treatment (120 s).

  14. Immunohistochemical study of semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 in the hippocampal vasculature: pathological synergy of Alzheimer's disease and diabetes mellitus.

    PubMed

    Valente, Tony; Gella, Alejandro; Solé, Montse; Durany, Núria; Unzeta, Mercedes

    2012-10-01

    Semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 (SSAO/VAP-1) is involved in vascular endothelial damage as well as in the vascular degeneration underlying diabetes mellitus and Alzheimer's disease (AD). Recent evidence suggests that classic pathological features of AD are more pronounced in diabetic mellitus patients. To investigate the expression and distribution of SSAO/VAP-1 in the two pathologies, we have performed an immunohistochemical study in human hippocampal vessels of AD, AD with diabetic mellitus (ADD), diabetic mellitus (DM), and nondemented (ND) patients. The present results demonstrate major vessel accumulation of both SSAO/VAP-1 and amyloid-β immunolabeling intensity in ADD compared with AD patients. Interestingly, nearly damaged vessels with high levels of SSAO/VAP-1 also showed increased oxidative damage markers (AGE, RAGE, and SOD-1) and glial activation (GFAP and HLA). Overall, this work suggests that high vascular SSAO/VAP-1 levels in human hippocampus may contribute to vascular degeneration, which can explain the severe progression in patients with both pathologies.

  15. 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.

  16. 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.

  17. Calcium Sensitive Fluorescent Dyes Fluo-4 and Fura Red under Pressure: Behaviour of Fluorescence and Buffer Properties under Hydrostatic Pressures up to 200 MPa

    PubMed Central

    Vass, H.; Reischl, B.; Allen, R. J.; Friedrich, O.

    2016-01-01

    The fluorescent Ca2+ sensitive dyes Fura Red (ratiometric) and Fluo-4 (non-ratiometric) are widely utilized for the optical assessment of Ca2+ fluctuations in vitro as well as in situ. The fluorescent behavior of these dyes is strongly depends on temperature, pH, ionic strength and pressure. It is crucial to understand the response of these dyes to pressure when applying calcium imaging technologies in the field of high pressure bioscience. Therefore, we use an optically accessible pressure vessel to pressurize physiological Ca2+-buffered solutions at different fixed concentrations of free Ca2+ (1 nM to 25.6 μM) and a specified dye concentration (12 μM) to pressures of 200 MPa, and record dye fluorescence intensity. Our results show that Fluo-4 fluorescence intensity is reduced by 31% per 100 MPa, the intensity of Fura Red is reduced by 10% per 100 MPa. The mean reaction volume for the dissociation of calcium from the dye molecules Δdv¯ is determined to -17.8 ml mol-1 for Fluo-4 and -21.3 ml mol-1 for Fura Red. Additionally, a model is presented that is used to correct for pressure-dependent changes in pH and binding affinity of Ca2+ to EGTA, as well as to determine the influence of these changes on dye fluorescence. PMID:27764134

  18. 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

  19. 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.

  20. Salt taste sensitivity thresholds in adolescents: are there any relationships with body composition and blood pressure levels?

    PubMed

    Kirsten, Vanessa Ramos; Wagner, Mário Bernardes

    2014-10-01

    The aim of this study was to identify the salt taste sensitivity thresholds and relationships with body composition and blood pressure levels in a cross-sectional study of adolescents. Blood pressure and body composition were measured with a digital device and by anthropometry, respectively. The salt taste sensitivity threshold was measured with 9 solutions with different sodium chloride concentrations to assess the sensitivity to saltiness. The solutions (4, 8, 15, 30, 60, 120, 250, 500 and 1000 mmol/L sodium chloride) were served in increasing concentrations until the taste was correctly identified. The taste sensitivity threshold was then classified as normal or high. In total, 421 adolescents (55.6% female), with an average age of 15.8 ± 0.91 years, were evaluated. The median threshold was 30 mmol/L, and 36.1% had a high threshold. The high blood pressure prevalence was 12.6%, and 25.5% of the subjects were overweight. When the mean systolic and diastolic blood pressure levels were compared between the normal and increased threshold groups after adjusting for gender, age, sedentary lifestyle and body mass index, only diastolic blood pressure showed a statistically significant effect (P < 0.0001) between the groups. The effect of a high threshold on body composition after adjusting for gender, age and physical inactivity was not significant (P = 0.177). There was no relationship between a high threshold and systolic pressure or body composition in the evaluated adolescents; therefore, only diastolic blood pressure was affected.

  1. Atmospheric pressure gas chromatography coupled to quadrupole-time of flight mass spectrometry as a powerful tool for identification of non intentionally added substances in acrylic adhesives used in food packaging materials.

    PubMed

    Canellas, E; Vera, P; Domeño, C; Alfaro, P; Nerín, C

    2012-04-27

    Acrylic adhesives are used to manufacture multilayer laminates that are used in food packaging to form the geometric shape of the package as well as to stick labels on the packages. Once applied on the packaging adhesives can supply potential migrants that could endanger the packaged food. Adhesives are complex matrices where intentionally and non intentionally added substances are present, but the identification of the migrants is required by law. In this study atmospheric pressure gas chromatography coupled to a quadrupole hyphenated to a time of flight mass spectrometer (APGC-MS/Q-TOF) has been explored for identification of unknowns coming from three different acrylic adhesives. The results are compared to those obtained by conventional GC-MS-Q (quadrupole). Sixteen compounds were identified by GC-MS/Q and five of them were confirmed by APGC-MS/Q-TOF as their molecular ions were found. Moreover, additional three new compounds were identified and their structure was elucidated working with the spectra obtained by APGC-MS/Q-TOF. This finding was very relevant as these compounds were biocides suspected to be allergenic and cytotoxic in humans. Migration studies were carried out using Tenax as solid food simulant and the results showed that the three acrylic adhesives tested in this work were safe for being used in food packaging materials since the migration of compounds previously identified was below the limit established in the current legislation.

  2. 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.

  3. Selection and Testing of Pressure and Temperature Sensitive Dyes for 2-D Flow Characterization via Synthesized Microbeads

    NASA Astrophysics Data System (ADS)

    Perez, Alex; Zhu, Cun; Xia, Younan; Khalil, Gamal; Dabiri, Dana

    2011-11-01

    Airborne temperature and pressure sensitive microbeads provide a vehicle with which to conduct two-dimensional flow characterization. An array of temperature and pressure sensitive dyes have been synthesized with microbeads (of silica, polystyrene, and polydimethylsiloxane) for this purpose. These microbeads were evaluated based on emission spectra, pressure response (0-760 torr), temperature response (5-45°C), and response time. Work will be presented showing the various combinations of dyes and microbead materials, as well as the testing process and examples of future application. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. #DEG-0718124, as well as National Science Foundation Grant No. NSF/CBET-IDR- 0929864.

  4. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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.

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

    PubMed

    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

  7. 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.

  8. Nebivolol, but not metoprolol, lowers blood pressure in nitric oxide-sensitive human hypertension.

    PubMed

    Okamoto, Luis E; Gamboa, Alfredo; Shibao, Cyndya A; Arnold, Amy C; Choi, Leena; Black, Bonnie K; Raj, Satish R; Robertson, David; Biaggioni, Italo

    2014-12-01

    Nebivolol, unlike other selective β1-receptor blockers, induces vasodilation attributable to increased NO bioavailability. The relative contribution of this mechanism to the blood pressure (BP)-lowering effects of nebivolol is unclear because it is normally masked by baroreflex buffering. Autonomic failure provides a unique model of hypertension devoid of autonomic modulation but sensitive to the hypotensive effects of NO potentiation. We tested the hypothesis that nebivolol would decrease BP in these patients through a mechanism independent of β-blockade. We randomized 20 autonomic failure patients with supine hypertension (14 men; 69±2 years) to receive a single oral dose of placebo, nebivolol 5 mg, metoprolol 50 mg (negative control), and sildenafil 25 mg (positive control) on separate nights in a double-blind, crossover study. Supine BP was monitored every 2 hours from 8:00 pm to 8:00 am. Compared with placebo, sildenafil and nebivolol decreased systolic BP during the night (P<0.001 and P=0.036, by mixed-effects model, maximal systolic BP reduction 8-hour postdrug of -20±6 and -24±9 mm Hg, respectively), whereas metoprolol had no effect. In a subanalysis, we divided patients into sildenafil responders (BP fall>20 mm Hg at 4:00 am) and nonresponders. Nebivolol significantly lowered systolic BP in sildenafil responders (-44±13 mm Hg) but not in nonresponders (1±11 mm Hg). Despite lowering nighttime BP, nebivolol did not worsen morning orthostatic tolerance compared with placebo. In conclusion, nebivolol effectively lowered supine hypertension in autonomic failure, independent of β1-blockade. These results are consistent with the hypothesis that NO potentiation contributes significantly to the antihypertensive effect of nebivolol.

  9. 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

  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. 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.

  12. 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

  13. 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.

  14. 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.

  15. Mental stress-induced increase in blood pressure is not related to baroreflex sensitivity in middle-aged healthy men.

    PubMed

    Fauvel, J P; Cerutti, C; Quelin, P; Laville, M; Gustin, M P; Paultre, C Z; Ducher, M

    2000-04-01

    The baroreflex that acts to blunt blood pressure (BP) variations through opposite variations in heart rate should limit the BP increase produced by an emotional challenge. However, relations between baroreflex sensitivity and BP reactivity induced by a psychological stress in a large group of adults have never been firmly established. In 280 healthy men, rest (10 minutes) and stress (5 minutes) BP and heart rate were recorded beat to beat by a blood pressure monitor. The mental stress was elicited by a well-standardized computerized version of a word color conflict stress test (Stroop Color Test). Rest and stress baroreflex sensitivity was assessed by the cross-spectral analysis of BP and heart rate and by the sequence method. The stress-induced increase in systolic BP (22.4+/-0.1 mm Hg) was not correlated with resting baroreflex sensitivity but was slightly correlated (r=0.2, P<0.001) with BP variability assessed either by standard deviation or by mid-frequency band spectral power. Our results suggested that a centrally mediated sympathetic stimulation overcame cardiac autonomic regulation and emphasized the role of the sympathetic vasoconstriction in the pressure response at the onset of the stressing stimulation. During the sustained sympathoexcitatory phase, the cardiac baroreflex blunts BP variations but at a lower sensitivity.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. Directly grown large area single-walled carbon nanotube films with very high sensitivity to normal pressure

    NASA Astrophysics Data System (ADS)

    Genest, Jonathan; Su Kim, Keun; Sauvé, Annick; Boissy, Patrick; Soucy, Gervais; Beauvais, Jacques

    2012-01-01

    Induction thermal plasma was used to grow a large area, ˜150 mm × 450 mm, and ˜1000 μm thick multi-layered carbon nanotube film. The film is made of a loosely woven structure of single-walled carbon nanotubes uniformly distributed among metallic impurities and carbon black particles. Under cyclic compressive strain, the film acts as a viscoelastic material. A model based on tunneling conduction was used to describe its high piezoresistive sensitivity to normal pressure. The gauge factor obtained for this film was 76.3, more than 20 times higher than the values achieved with a standard buckypaper made from the same nanotube source. This fast and straightforward approach for synthesizing pressure sensitive films is done directly inside the processing system during the growth of the carbon nanotubes. It could provide the means for producing low cost large-scale sensors, such as smart materials for civil and mechanical structures.

  5. 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.

  6. 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.

  7. Self-Powered High-Resolution and Pressure-Sensitive Triboelectric Sensor Matrix for Real-Time Tactile Mapping.

    PubMed

    Wang, Xiandi; Zhang, Hanlu; Dong, Lin; Han, Xun; Du, Weiming; Zhai, Junyi; Pan, Caofeng; Wang, Zhong Lin

    2016-04-20

    A triboelectric sensor matrix (TESM) can accurately track and map 2D tactile sensing. A self-powered, high-resolution, pressure-sensitive, flexible and durable TESM with 16 × 16 pixels is fabricated for the fast detection of single-point and multi-point touching. Using cross-locating technology, a cross-type TESM with 32 × 20 pixels is developed for more rapid tactile mapping, which significantly reduces the addressing lines from m × n to m + n.

  8. 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

  9. Single cell adhesion assay using computer controlled micropipette.

    PubMed

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

    2014-01-01

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

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. The association of genetic variations with sensitivity of blood pressure to dietary salt: A narrative literature review.

    PubMed

    Doaei, Saeid; Gholamalizadeh, Maryam

    2014-05-01

    Salt sensitivity of blood pressure (BP) is an independent risk factor for cardiovascular morbidity. Up to 50% of patients with essential hypertension are salt-sensitive, as manifested by a rise in BP with salt intake. Several genetic variations have been identified as being associated with salt sensitivity. The present study aimed to review the evidence on the effect of gene polymorphisms on the salt sensitivity of BP. We searched in PubMed website from 1990 to 2011, with the use of following keywords: "hypertension, dietary salt, polymorphisms, and blood pressure". The effect of sodium intake on BP differed by genotype at the genes of the renin-angiotensin system, aldosterone synthase, cytochrome p450 3A, epithelial sodium channel genes, genes of sympathetic nervous system, β-3 subunit of G-protein, alpha-adducin, endothelial nitric oxide synthase, Kallikrein-Kinin system. These approaches suggest that these polymorphisms may be potentially useful genetic markers of BP response to dietary salt. There is evidence that genetic predisposition modulates the BP response to diet. Therefore, diet and nutrition can mitigate or enhance the effects of genetic predisposition. Increasing our knowledge of this relationship can lead to individualized treatment and increased understanding of hypertension. PMID:25161689

  16. Pressure-Sensitivity and Constitutive Modeling of AN Elastomer at High Strain Rates

    NASA Astrophysics Data System (ADS)

    Jiao, T.; Clifton, R. J.; Grunschel, S. E.

    2009-12-01

    Pressure-shear plate impact experiments have been conducted to study the pressure dependence of the shearing resistance of an elastomer (polyurea) at very high strain rates: 105-106 s-1. Two impact configurations were used. In the first, an unloading longitudinal wave reflected from the rear surface of the target assembly arrives at the sample midway through its loading by the incident shear wave. In the second, an unloading wave reflected from the free rear surface of the flyer arrives at the sample prior to the arrival of the incident shear wave. As a result, the sample is sheared at high strain rates—at both high and low pressure—during a single experiment (first case) or at high strain rates and low pressures (second case). Based on the experimental results, a constitutive model has been developed that involves a hyperelastic spring acting in parallel with an elastic spring and viscoplastic dashpot acting in series. The viscoplastic dashpot is modeled by means of a thermal activation model in which the activation energy is taken to be pressure dependent. Parameters in this model are determined from experimental data. Good agreement between measured and computed wave profiles is obtained over the entire range of pressures used in the experiments.

  17. Tactile surface classification for limbed robots using a pressure sensitive robot skin.

    PubMed

    Shill, Jacob J; Collins, Emmanuel G; Coyle, Eric; Clark, Jonathan

    2015-02-02

    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.

  18. Oxygen Quenching of Luminescence of Pressure Sensitive Paint for Wind Tunnel Research

    NASA Astrophysics Data System (ADS)

    Gouterman, Martin

    1997-06-01

    A technique for measuring the lift on airfoils in wind tunnels has been developed based on oxygen quenching of luminescence. A luminophor that is quenched by oxygen is dissolved in a paint containing polymer that is oxygen permeable and a volatile solvent. The paint is sprayed to form a coating on the airfoil surface. The intensity of photo excited emission depends on the effective oxygen pressure over the surface. During airflow this is reduced and the emission gets brighter. The ratio of a CCD camera image of the emission intensity taken in still air to that taken during airflow provides a map of the pressure on the airfoil surface. This is given by the Stern-Volmer equation: Io(x,y)/I(x,y) = A + B(pxy/po) where Io(x,y) is the intensity measured at point x,y in still air at pressure po, I(x,y) is the intensity at the same point during airflow, pxy is the pressure at that point during airflow, and A and B are calibration constants. The luminophor of choice was a platinum porphyrin that is excited in the near uv and emits a phosphorescence at 650 nm. The most serious problem with the method is that the emission intensity is also temperature dependent.

  19. 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

  20. 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.

  1. 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

  2. 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...

  3. 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.

  4. 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

  5. Characterizations of Inorganic Electro-Luminescence as an Excitation Source of Pressure-Sensitive Paint Measurement System

    NASA Astrophysics Data System (ADS)

    Iijima, Yoshimi; Sakaue, Hirotaka

    2013-11-01

    Electro-luminescence based pressure-sensitive paint (EL-PSP) system uses an inorganic EL as an excitation source for a PSP measurement. It can be directly applied onto a PSP model to eliminate a remote illumination, and gives a uniform illumination on a PSP model without moving/re-directing the illumination. The temperature dependency of the EL-PSP system can be reduced by the opposite temperature dependency of the EL and PSP. An inorganic EL needs an AC input for illumination that creates a periodic excitation of a PSP. It is necessary to characterize the periodic illumination of the EL in terms of a PSP excitation source. At present, it is found that a single pulse of the EL is dependent on the temperature but independent of the pressure. In the presentation, we discuss further the characterizations of the EL as an illumination source of PSP. These include the frequency of the EL illumination and the illumination pattern.

  6. 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.

  7. 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.

  8. Pore-pressure sensitivities to dynamic strains: observations in active tectonic regions

    USGS Publications Warehouse

    Barbour, Andrew

    2015-01-01

    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 hydro-mechanical 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 through 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 non-linearly on the inverse fault-perpendicular distance, with the response decreasing towards 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

  9. 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.

  10. 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.

  11. Adhesive plasters

    DOEpatents

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

    1978-01-01

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

  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. An electrically and mechanically self-healing composite with pressure- and flexion-sensitive properties for electronic skin applications.

    PubMed

    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.

  15. 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.

  16. Reproducing Kernel Particle Method in Plasticity of Pressure-Sensitive Material with Reference to Powder Forming Process

    NASA Astrophysics Data System (ADS)

    Khoei, A. R.; Samimi, M.; Azami, A. R.

    2007-02-01

    In this paper, an application of the reproducing kernel particle method (RKPM) is presented in plasticity behavior of pressure-sensitive material. The RKPM technique is implemented in large deformation analysis of powder compaction process. The RKPM shape function and its derivatives are constructed by imposing the consistency conditions. The essential boundary conditions are enforced by the use of the penalty approach. The support of the RKPM shape function covers the same set of particles during powder compaction, hence no instability is encountered in the large deformation computation. A double-surface plasticity model is developed in numerical simulation of pressure-sensitive material. The plasticity model includes a failure surface and an elliptical cap, which closes the open space between the failure surface and hydrostatic axis. The moving cap expands in the stress space according to a specified hardening rule. The cap model is presented within the framework of large deformation RKPM analysis in order to predict the non-uniform relative density distribution during powder die pressing. Numerical computations are performed to demonstrate the applicability of the algorithm in modeling of powder forming processes and the results are compared to those obtained from finite element simulation to demonstrate the accuracy of the proposed model.

  17. Self-assembly of DNA and cell-adhesive proteins onto pH-sensitive inorganic crystals for precise and efficient transgene delivery.

    PubMed

    Chowdhury, E H

    2008-01-01

    Intracellular delivery of a functional gene or a gene-silencing DNA or RNA sequence is expected to be a powerful tool for treating critical human diseases very precisely and effectively. One of the major hurdles to the successful delivery of a nucleic acid with nanoparticles is the transport across the plasma membrane. The existence of various and numerous cell surface receptors with potential capability of being internalized by cells upon ligand binding unveils the ways of overcoming the barrier by targeting the nanoparticles to specific receptor. This review will reveal the current progress on utilizing the cell adhesion molecules as targeting receptors for transgene delivery, with a special focus on the design of bio-functionalized inorganic nanocrystals using both naturally occurring and genetically engineered cell adhesive proteins for high efficiency transfection of embryonic stem cells. Self-assembly of both DNA and cell-adhesive proteins, such as fibronectin and E-cadherin-Fc into the growing nanocrystals of carbonate apatite leads to their high affinity interactions with fibronectin-specific integrins and E-cadherin in embryonic stem cell surface and accelerates transgene delivery for subsequent expression. While only apatite nano-particles were very inefficient in transfecting embryonic stem cells, fibronectin-anchored particles and to a more significant extent, fibronectin and E-cadherin-Fc-associated particles dramatically enhanced transgene delivery with a value notably higher than that of commercially available lipofection system. Activation of protein kinase C (PKC) dramatically enhances transgene expression probably by up-regulating both integrin and E-cadherin. Thus, the new establishment of a bio-functional hybrid gene-carrier would promote and facilitate development of stem cell-based therapy in regenerative medicine.

  18. 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

  19. 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.

  20. Pressure-dependent contribution of Rho kinase-mediated calcium sensitization in serotonin-evoked vasoconstriction of rat cerebral arteries.

    PubMed

    El-Yazbi, Ahmed F; Johnson, Rosalyn P; Walsh, Emma J; Takeya, Kosuke; Walsh, Michael P; Cole, William C

    2010-05-15

    Our understanding of the cellular signalling mechanisms contributing to agonist-induced constriction is almost exclusively based on the study of conduit arteries. Resistance arteries/arterioles have received less attention as standard biochemical approaches lack the necessary sensitivity to permit quantification of phosphoprotein levels in these small vessels. Here, we have employed a novel, highly sensitive Western blotting method to assess: (1) the contribution of Ca(2+) sensitization mediated by phosphorylation of myosin light chain phosphatase targeting subunit 1 (MYPT1) and the 17 kDa PKC-potentiated protein phosphatase 1 inhibitor protein (CPI-17) to serotonin (5-HT)-induced constriction of rat middle cerebral arteries, and (2) whether there is any interplay between pressure-induced myogenic and agonist-induced mechanisms of vasoconstriction. Arterial diameter and levels of MYPT1 (T697 and T855), CPI-17 and 20 kDa myosin light chain subunit (LC(20)) phosphorylation were determined following treatment with 5-HT (1 micromol l(1)) at 10 or 60 mmHg in the absence and presence of H1152 or GF109203X to suppress the activity of Rho-associated kinase (ROK) and protein kinase C (PKC), respectively. Although H1152 and GF109203X suppressed 5-HT-induced constriction and reduced phospho-LC(20) content at 10 mmHg, we failed to detect any increase in MYPT1 or CPI-17 phosphorylation. In contrast, an increase in MYPT1-T697 and MYPT1-T855 phosphorylation, but not phospho-CPI-17 content, was apparent at 60 mmHg following exposure to 5-HT, and the phosphorylation of both MYPT1 sites was sensitive to H1152 inhibition of ROK. The involvement of MYPT1 phosphorylation in the response to 5-HT at 60 mmHg was not dependent on force generation per se, as inhibition of cross-bridge cycling with blebbistatin (10 micromol l(1)) did not affect phosphoprotein content. Taken together, the data indicate that Ca(2+) sensitization owing to ROK-mediated phosphorylation of MYPT1 contributes to 5

  1. New Measurement Service for Determining Pressure Sensitivity of Type LS2aP Microphones by the Reciprocity Method

    PubMed Central

    Wagner, Randall P.; Nedzelnitsky, Victor; Fick, Steven E.

    2011-01-01

    A new National Institute of Standards and Technology (NIST) measurement service has been developed for determining the pressure sensitivities of American National Standards Institute and International Electrotechnical Commission type LS2aP laboratory standard microphones over the frequency range 31.5 Hz to 20 000 Hz. At most frequencies common to the new service and the old service, the values of the expanded uncertainties of the new service are one-half the corresponding values of the old service, or better. The new service uses an improved version of the system employed by NIST in the Consultative Committee for Acoustics, Ultrasound, and Vibration (CCAUV) key comparison CCAUV.A-K3. Measurements are performed using a long and a short air-filled plane-wave coupler. For each frequency in the range 31.5 Hz to 2000 Hz, the reported sensitivity level is the average of data from both couplers. For each frequency above 2000 Hz, the reported sensitivity level is determined with data from the short coupler only. For proof test data in the frequency range 31.5 Hz to 2000 Hz, the average absolute differences between data from the long and the short couplers are much smaller than the expanded uncertainties. PMID:26989598

  2. Ontogeny of blood pressure in the inbred Dahl hypertension-sensitive and -resistant rat.

    PubMed

    Kaskel, F J; Devarajan, P; Persan, L; Juno, C J; Wilson, T A; McCaughran, J A

    1988-07-01

    The inbred S/JR rat is characterized by a genetic predisposition to NaCl-induced hypertension. Although mature S/JR but not R/JR rats develop hypertension when fed a high NaCl-containing diet, this effect has not been examined during early neonatal development. S/JR and R/JR dams were maintained on 0.15% (w/w) or 8% (w/w) NaCl diets throughout gestation and lactation. Measurements of mean abdominal aortic blood pressure (MAP) were obtained in anesthetized offspring at 5, 15, and 25 days of age. This was greater in neonatal S/JR rats than R/JR rats at 5, 15, and 25 days of age. A hypertensinogenic effect of 8% NaCl was seen in R/JR at 5 and 15 days. The results indicate that the ontogeny of MAP can be influenced by pre- and postnatal dietary NaCl. More importantly, elevated MAP in the S/JR strain is a distinguishing characteristic evident throughout the neonatal period of development.

  3. 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.

  4. Direction sensitive fall detection using a triaxial accelerometer and a barometric pressure sensor.

    PubMed

    Tolkiehn, Marie; Atallah, Louis; Lo, Benny; Yang, Guang-Zhong

    2011-01-01

    Falling is one of the leading causes of serious health decline or injury-related deaths in the elderly. For survivors of a fall, the resulting health expenses can be a devastating burden, largely because of the long recovery time and potential comorbidities that ensue. The detection of a fall is, therefore, important in care of the elderly for decreasing the reaction time by the care-givers especially for those in care who are particularly frail or living alone. Recent advances in motion-sensor technology have enabled wearable sensors to be used efficiently for pervasive care of the elderly. In addition to fall detection, it is also important to determine the direction of a fall, which could help in the location of joint weakness or post-fall fracture. This work uses a waist-worn sensor, encompassing a 3D accelerometer and a barometric pressure sensor, for reliable fall detection and the determination of the direction of a fall. Also assessed is an efficient analysis framework suitable for on-node implementation using a low-power micro-controller that involves both feature extraction and fall detection. A detailed laboratory analysis is presented validating the practical application of the system.

  5. Effects of protein intake on blood pressure, insulin sensitivity and blood lipids in children: a systematic review.

    PubMed

    Voortman, Trudy; Vitezova, Anna; Bramer, Wichor M; Ars, Charlotte L; Bautista, Paula K; Buitrago-Lopez, Adriana; Felix, Janine F; Leermakers, Elisabeth T M; Sajjad, Ayesha; Sedaghat, Sanaz; Tharner, Anne; Franco, Oscar H; van den Hooven, Edith H

    2015-02-14

    High protein intake in early childhood is associated with obesity, suggesting possible adverse effects on other cardiometabolic outcomes. However, studies in adults have suggested beneficial effects of protein intake on blood pressure (BP) and lipid profile. Whether dietary protein intake is associated with cardiovascular and metabolic health in children is unclear. Therefore, we aimed to systematically review the evidence on the associations of protein intake with BP, insulin sensitivity and blood lipids in children. We searched the databases Medline, Embase, Cochrane Central and PubMed for interventional and observational studies in healthy children up to the age of 18 years, in which associations of total, animal and/or vegetable protein intake with one or more of the following outcomes were reported: BP; measures of insulin sensitivity; cholesterol levels; or TAG levels. In the search, we identified 6636 abstracts, of which fifty-six studies met all selection criteria. In general, the quality of the included studies was low. Most studies were cross-sectional, and many did not control for potential confounders. No overall associations were observed between protein intake and insulin sensitivity or blood lipids. A few studies suggested an inverse association between dietary protein intake and BP, but evidence was inconclusive. Only four studies examined the effects of vegetable or animal protein intake, but with inconsistent results. In conclusion, the literature, to date provides insufficient evidence for effects of protein intake on BP, insulin sensitivity or blood lipids in children. Future studies could be improved by adequately adjusting for key confounders such as energy intake and obesity.

  6. 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

  7. Heat-shrinkable film improves adhesive bonds

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  8. Ultra-low sensitivity to temperature low-cost optical fiber Fabry-Perot micro pressure sensor with a chitosan diaphragm

    NASA Astrophysics Data System (ADS)

    Wang, Wenhua; Li, Sidong; Wen, Lili

    2013-11-01

    In this paper, a low-cost CDEFPI (chitosan diaphragm-based extrinsic Fabry-Perot interferometer) micro pressure sensor with high sensitivity and ultra-low temperature dependence is proposed. The chitosan diaphragm is achieved through crosslinking method via glutaraldehyde which reduces extremely the water swelling property of chitosan and improves greatly the performance of sensor. A vent hole leaving during laser heating fusion bonding process guarantees the ultra-low temperature sensitivity of the sensor. The CDEFPI pressure sensor with a sensitivity of 25.65 nm/kPa (176.86 nm/psi), a resolution of 7.8 Pa (0.001 psi), temperature sensitivity of 0.015 nm/°C, and a thermal induced pressure measurement error limited within 0.0005 kPa/°C (0.00007 psi/°C) has been demonstrated.

  9. Visualization of jet flows over a plate by pressure-sensitive paint experiments and comparison with CFD.

    PubMed

    Fujii, Kozo; Tsuboi, Nobuyuki; Fujimatsu, Nobuyoshi

    2002-10-01

    Flow fields created by underexpanded sonic jets impinging on an inclined flat plate were studied experimentally using the pressure sensitive paint (PSP) measurement technique. The measurement system and some representative results are presented here. Two binders, thin-layer chromatography (TLC) plates and anodized aluminum (A-A) plates were tested with bathophen ruthenium chloride as a luminophore. The results show that both the binders can be used. TLC plates are preferable because their luminescent intensity is almost twice that of the A-A plates. Quantitative measurements require accurate temperature calibration. A preliminary effort to elucidate the flow structure by combining the PSP results with a computer simulation of the same flow field is presented. Although good agreement is obtained between the experimental and numerical results, future quantitative comparisons are necessary to yield a useful tool in the analysis of the jet-plate interaction flows.

  10. 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

  11. 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.

  12. Single-point but not tonic cuff pressure pain sensitivity is associated with level of physical fitness--a study of non-athletic healthy subjects.

    PubMed

    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.

  13. 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

  14. Sensitive analysis of carbon, chromium and silicon in steel using picosecond laser induced low pressure helium plasma

    NASA Astrophysics Data System (ADS)

    Abdulmadjid, Syahrun Nur; Idris, Nasrullah; Pardede, Marincan; Jobiliong, Eric; Hedwig, Rinda; Lie, Zener Sukra; Suyanto, Hery; Tjia, May On; Kurniawan, Koo Hendrik; Kagawa, Kiichiro

    2015-12-01

    An experimental study has been performed on the gas pressure and laser energy dependent variations of plasma emission intensities in Ar, He and N2 ambient gases induced by picosecond (ps) Nd-YAG laser irradiation on low alloy steel (JSS) samples. The study is aimed to demonstrate distinct advantage of using low pressure He ambient gas in combination with ps laser for the sensitive ppm level detection of C, Si and Cr emission lines in the UV-VIS spectral region. The much shorter pulses of ps laser are chosen for the effective ablation at much lower energy and for the benefit of reducing the undesirable long heating of the sample surface. It is found that the C I 247.8 nm, Fe I 253.5 nm, and Si I 251.4 nm emission lines induced by the ps laser at 15 mJ are readily detected with He ambient gas of 2.6 kPA, featuring generally sharp spectral signals with very low background. The following experimental results using samples with various concentrations of C, Si and Cr impurities are shown to produce for each of those elements a linear calibration line with extrapolated zero intercept, demonstrating the applicability for their quantitative analyses, with a preliminary estimated detection limits of 20 μg/g, 15 μg/g, and 5 μg/g, for C, Si, and Cr, respectively. The possibility of applying the same setup for concentration depth profiling is also demonstrated.

  15. Lifetime Characterization of Electro-Luminescence Based Pressure-Sensitive Paint System for Unsteady Flow Field Measurements

    NASA Astrophysics Data System (ADS)

    Iijima, Yoshimi; Sakaue, Hirotaka

    2012-11-01

    Electro-luminescence based pressure-sensitive paint (EL-PSP) system uses an EL as an illumination source for a PSP measurement. EL can be directly applied onto a PSP model to eliminate a remote illumination. This gives a uniform illumination on a PSP model without moving/re-directing the illumination. The temperature dependency can be reduced by the opposite temperature dependency of the EL and PSP. At present, the system is demonstrated in a steady flow field. To extend the system for capturing an unsteady flow field, a fast responding PSP and the lifetime characterization of the system are required. The former can be achieved by using a porous PSP. The latter is discussed in the present presentation. The EL-PSP system needs an AC input to illuminate the EL, which gives a pulsed/periodic excitation to a PSP. This limits the acquisition timing of the flow field; a frequent timing can resolve a fast unsteady flow field. The lifetime of the PSP emission can be related to the pressure. The lifetime decays of the EL and PSP are measured to discuss the lifetime characterization of the system.

  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.

  17. 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.

  18. 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.

  19. The role of the kallikrein-kinin system genes in the salt sensitivity of blood pressure: the GenSalt Study.

    PubMed

    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

    2012-10-01

    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

  20. Effects of gas or vapor adsorption on adhesion, friction, and wear of solid interfaces.

    PubMed

    Barthel, Anthony J; Al-Azizi, Ala'; Surdyka, Nicholas D; Kim, Seong H

    2014-03-25

    The adsorption of vapor molecules plays an important role in countless fields and is increasingly realized to be critical in tribology, which encompasses adhesion, friction, and wear of surfaces. This feature article reviews experimental methods for quantifying gas and vapor adsorption on flat solid surfaces under equilibrium conditions (ambient pressure and temperature) as well as the effects of these adsorbates on the adhesion, friction, and wear of various materials. Particular attention is given to species that are present in the ambient environment such as water (humidity) and organic vapors. These adsorbed species can have drastic yet varied influences on tribology depending on the surface chemistry of materials. Despite prolonged and ubiquitous observations in a broad range of materials and vapors, a fundamental understanding of the effect of adsorbed gases and vapors on the adhesion, friction, and wear of surfaces has begun only recently through surface-sensitive characterization. PMID:24180252

  1. Diode laser detection of greenhouse gases in the near-infrared region by wavelength modulation spectroscopy: pressure dependence of the detection sensitivity.

    PubMed

    Asakawa, Takashi; Kanno, Nozomu; Tonokura, Kenichi

    2010-01-01

    We have investigated the pressure dependence of the detection sensitivity of CO(2), N(2)O and CH(4) using wavelength modulation spectroscopy (WMS) with distributed feed-back diode lasers in the near infrared region. The spectral line shapes and the background noise of the second harmonics (2f) detection of the WMS were analyzed theoretically. We determined the optimum pressure conditions in the detection of CO(2), N(2)O and CH(4), by taking into consideration the background noise in the WMS. At the optimum total pressure for the detection of CO(2), N(2)O and CH(4), the limits of detection in the present system were determined.

  2. Simultaneous Reference- and Signal-Imaging for Cancellation of Unsteady Motion in Pressure-Sensitive Paint Measurement

    NASA Astrophysics Data System (ADS)

    Miyamoto, Kensuke; Miyazaki, Takeshi; Sakaue, Hirotaka

    2009-11-01

    Simultaneous reference- and signal-image acquisition for pressure-sensitive paint (PSP) measurement is presented in this paper. The system to acquire these images consists of a two-color PSP and a high-speed CCD camera. The two-color PSP provides a reference and a signal luminescence separated by their luminescent peak wavelengths of 520 nm and 620 nm, respectively. The reference luminescent image is acquired through a green filtered CCD, while the signal image through a red filtered CCD. This system can cancel a non-uniform illumination for exciting two-color PSP as well as a non-uniform image acquisition of a CCD camera due to the location between the camera and the testing object. This system can be applied to a PSP measurement, which includes translation, vibration, and deformation of the testing object. Our measurement system is thus advantage from a conventional PSP measurement, which requires stationary location among the testing object, camera, and illumination source. Unsteady motion of a plate coated with our two-color PSP is included as a demonstration. The developed system captured the unsteady motion as well as gas impingement on the coated plate with camera frame rate of 300 Hz.

  3. 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

  4. 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.

  5. 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.

  6. Numerical solution for 5-layer laminate technique to determine saturation solubility of a drug in a thin film of pressure sensitive adhesive.

    PubMed

    Bänsch, Eberhard; Reismann, Simone; Lee, Geoffrey

    2014-08-01

    A numerical solution of the one-dimensional diffusion equation is presented to describe the 5-layer laminate technique for estimating the saturation solubility of a drug in a thin polymer film. The boundary and initial conditions encompass a donor layer, a separating membrane, and an acceptor layer. Alteration of the drug's partition coefficient between donor and separating membrane has little influence on drug accumulation with the acceptor. The diffusivity in the separating membrane should be high to promote a short experimental time to achieve saturation equilibrium in the acceptor layer. The essential parameter to give rapid equilibrium is the thickness of the acceptor polymer film. For values of diffusivity typical for drugs of molecular weight around 500 an acceptor layer thickness of 10 µm-20 µm is required to achieve equilibrium within less than 10 d. These simulations allow the selection of suitable experimental conditions to make the 5-layer laminate technique a viable method for routine use. PMID:23944998

  7. 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

  8. 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

  9. 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.

  10. VCAM-1 directed target-sensitive liposomes carrying CCR2 antagonists bind to activated endothelium and reduce adhesion and transmigration of monocytes.

    PubMed

    Calin, Manuela; Stan, Daniela; Schlesinger, Martin; Simion, Viorel; Deleanu, Mariana; Constantinescu, Cristina Ana; Gan, Ana-Maria; Pirvulescu, Monica Madalina; Butoi, Elena; Manduteanu, Ileana; Bota, Marian; Enachescu, Marius; Borsig, Lubor; Bendas, Gerd; Simionescu, Maya

    2015-01-01

    Chemokines are critically involved in the development of chronic inflammatory-associated diseases such as atherosclerosis. We hypothesized that targeted delivery of compounds to the surface of activated endothelial cells (EC) interferes with chemokine/receptor interaction and thereby efficiently blocks inflammation. We developed PEGylated target-sensitive liposomes (TSL) encapsulating a CCR2 antagonist (Teijin compound 1) coupled with a specific peptide recognized by endothelial VCAM-1 (Vp-TSL-Tj). TSL were characterized for size (by dynamic light scattering), the amount of peptide coupled at the liposomal surface and Teijin release (by HPLC). We report that Vp-TSL-Tj binds specifically to activated EC in vitro and in situ, release the entrapped Teijin and prevent the transmigration of monocytes through activated EC. This is the first evidence that nanocarriers which transport and release chemokine inhibitors at specific pathological sites can reduce chemokine-dependent inflammatory processes.

  11. 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

  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.

  13. Modulation of membrane properties of lung cancer cells by azurin enhances the sensitivity to EGFR-targeted therapy and decreased β1 integrin-mediated adhesion.

    PubMed

    Bernardes, Nuno; Abreu, Sofia; Carvalho, Filomena A; Fernandes, Fábio; Santos, Nuno C; Fialho, Arsénio M

    2016-06-01

    In lung cancer, the Epidermal Growth Factor Receptor (EGFR) is one of the main targets for clinical management of this disease. The effectiveness of therapies toward this receptor has already been linked to the expression of integrin receptor subunit β1 in NSCLC A549 cells. In this work we demonstrate that azurin, an anticancer therapeutic protein originated from bacterial cells, controls the levels of integrin β1 and its appropriate membrane localization, impairing the intracellular signaling cascades downstream these receptors and the invasiveness of cells. We show evidences that azurin when combined with gefitinib and erlotinib, tyrosine kinase inhibitors which targets specifically the EGFR, enhances the sensitivity of these lung cancer cells to these molecules. The broad effect of azurin at the cell surface level was examined by Atomic Force Microscopy. The Young 's module (E) shows that the stiffness of A549 lung cancer cells decreased with exposure to azurin and also gefitinib, suggesting that the alterations in the membrane properties may be the basis of the broad anticancer activity of this protein. Overall, these results show that azurin may be relevant as an adjuvant to improve the effects of other anticancer agents already in clinical use, to which patients often develop resistance hampering its full therapeutic response.

  14. Highly Sensitive and Multifunctional Tactile Sensor Using Free-standing ZnO/PVDF Thin Film with Graphene Electrodes for Pressure and Temperature Monitoring

    NASA Astrophysics Data System (ADS)

    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.

  15. 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

    2015-01-20

    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.

  16. 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

  17. 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

  18. 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 Central

    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

  19. 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

    2014-10-10

    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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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

  9. Mini-review: barnacle adhesives and adhesion.

    PubMed

    Kamino, Kei

    2013-01-01

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

  10. 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.

  11. 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.

  12. 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

  13. 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).

  14. 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).

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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.

  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