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Sample records for advanced antifouling coating

  1. Transport and antifouling properties of papain-based antifouling coatings

    NASA Astrophysics Data System (ADS)

    Peres, Rafael S.; Armelin, Elaine; Moreno-Martínez, Juan A.; Alemán, Carlos; Ferreira, Carlos A.

    2015-06-01

    The aim of this work is to study the antifouling performance and water uptake behaviour of coatings formulated with papain (an environmentally friendly pigment). Antifouling coatings have been formulated using rosin (natural resin) as matrix and papain adsorbed in activated carbon as pigment. Electrochemical impedance spectroscopy (EIS) measurements were used to evaluate the behaviour of the formulated coatings in the marine environment and to calculate the apparent water coefficient of diffusion (D). FTIR and XPS analyses confirm the presence of papain adsorbed inside the activated carbon pores and the release of papain in water. Immersion tests in the Mediterranean Sea were carried out for 7 months to verify the degree of biofouling of the tested coatings. These field assays clearly indicate the excellent behaviour of papain-based antifouling coatings; the results being similar to those achieved using a commercial coating. Additionally, the EIS technique is shown to be a great tool to predict the coating diffusivity of antifouling coatings before immersion tests. Furthermore, the use of biodegradable papain as a nature-friendly antifouling agent can eliminate the negative environmental impact caused by metals and chemical biocides typically used in current commercial formulations.

  2. Industrial Market Research Report: Feasibility of commercialization of the advanced antifouling coating of Copperlok, Inc

    SciTech Connect

    Gormley, G.J.

    1990-10-01

    The Copperlok antifouling process was designed to prevent marine growth on surfaces exposed to sea water. It is a method of bonding thermally sprayed Cu and Cu alloys onto an epoxy material containing microballoons (hollow spheres). After the epoxy cures, the surface is abraded so that the microballoons are fractured, exposing microscopic concave porosity. The sprayed material is directed to the surface, where it impregnates the pores, bridges and then welds across the surface, creating a very thin laminate of the metal materials security bonded to the bond coat and to the substrate. The Copperlok process laminates an approximate layer of Cu-Ni alloy 8 mils thick with an expected active life of 15--20 y. This report addresses the perceived acceptability of the process in several different marketplaces with the hope of directing the invention to the most receptive consumer group. The opinion surveys of the recreational marine industry were limited to the three coastal areas of the Atlantic, Gulf, and Pacific.

  3. Industrial Market Research Report: Feasibility of commercialization of the advanced antifouling coating of Copperlok, Inc.

    SciTech Connect

    Gormley, G.J.

    1990-10-01

    The Copperlok antifouling process was designed to prevent marine growth on surfaces exposed to sea water. It is a method of bonding thermally sprayed Cu and Cu alloys onto an epoxy material containing microballoons (hollow spheres). After the epoxy cures, the surface is abraded so that the microballoons are fractured, exposing microscopic concave porosity. The sprayed material is directed to the surface, where it impregnates the pores, bridges and then welds across the surface, creating a very thin laminate of the metal materials security bonded to the bond coat and to the substrate. The Copperlok process laminates an approximate layer of Cu-Ni alloy 8 mils thick with an expected active life of 15--20 y. This report addresses the perceived acceptability of the process in several different marketplaces with the hope of directing the invention to the most receptive consumer group. The opinion surveys of the recreational marine industry were limited to the three coastal areas of the Atlantic, Gulf, and Pacific.

  4. Switchable antifouling coatings and uses thereof

    DOEpatents

    Denton, Michele L. Baca; Dirk, Shawn M.; Johnson, Ross Stefan

    2017-02-28

    The present invention relates to antifouling coatings capable of being switched by using heat or ultraviolet light. Prior to switching, the coating includes an onium cation component having antimicrobial and antibacterial properties. Upon switching, the coating is converted to a conjugated polymer state, and the cationic component is released with any adsorbed biofilm layer. Thus, the coatings herein have switchable and releasable properties. Methods of making and using such coatings are also described.

  5. Antifouling properties of zinc oxide nanorod coatings.

    PubMed

    Al-Fori, Marwan; Dobretsov, Sergey; Myint, Myo Tay Zar; Dutta, Joydeep

    2014-01-01

    In laboratory experiments, the antifouling (AF) properties of zinc oxide (ZnO) nanorod coatings were investigated using the marine bacterium Acinetobacter sp. AZ4C, larvae of the bryozoan Bugula neritina and the microalga Tetraselmis sp. ZnO nanorod coatings were fabricated on microscope glass substrata by a simple hydrothermal technique using two different molar concentrations (5 and 10 mM) of zinc precursors. These coatings were tested for 5 h under artificial sunlight (1060 W m(-2) or 530 W m(-2)) and in the dark (no irradiation). In the presence of light, both the ZnO nanorod coatings significantly reduced the density of Acinetobacter sp. AZ4C and Tetraselmis sp. in comparison to the control (microscope glass substratum without a ZnO coating). High mortality and low settlement of B. neritina larvae was observed on ZnO nanorod coatings subjected to light irradiation. In darkness, neither mortality nor enhanced settlement of larvae was observed. Larvae of B. neritina were not affected by Zn(2+) ions. The AF effect of the ZnO nanorod coatings was thus attributed to the reactive oxygen species (ROS) produced by photocatalysis. It was concluded that ZnO nanorod coatings effectively prevented marine micro and macrofouling in static conditions.

  6. Bioinspired catecholic copolymers for antifouling surface coatings.

    PubMed

    Cho, Joon Hee; Shanmuganathan, Kadhiravan; Ellison, Christopher J

    2013-05-01

    We report here a synthetic approach to prepare poly(methyl methacrylate)-polydopamine diblock (PMMA-PDA) and triblock (PDA-PMMA-PDA) copolymers combining mussel-inspired catecholic oxidative chemistry and atom transfer radical polymerization (ATRP). These copolymers display very good solubility in a range of organic solvents and also a broad band photo absorbance that increases with increasing PDA content in the copolymer. Spin-cast thin films of the copolymer were stable in water and showed a sharp reduction (by up to 50%) in protein adsorption compared to those of neat PMMA. Also the peak decomposition temperature of the copolymers was up to 43°C higher than neat PMMA. The enhanced solvent processability, thermal stability and low protein adsorption characteristics of this copolymer makes it attractive for variety of applications including antifouling coatings on large surfaces such as ship hulls, buoys, and wave energy converters.

  7. Patterning and biofunctionalization of antifouling hyperbranched polyglycerol coatings.

    PubMed

    Moore, Eli; Delalat, Bahman; Vasani, Roshan; Thissen, Helmut; Voelcker, Nicolas H

    2014-07-14

    We demonstrate the patterned biofunctionalization of antifouling hyperbranched polyglycerol (HPG) coatings on silicon and glass substrates. The ultralow fouling HPG coatings afforded straightforward chemical handles for rapid bioconjugation of amine containing biomolecular species. This was achieved by sodium periodate oxidation of terminal HPG diols to yield reactive aldehyde groups. Patterned microprinting of sodium periodate and cell adhesion mediating cyclic peptides containing the RGD sequence resulted in an array of covalently immobilized bioactive signals. When incubated with mouse fibroblasts, the HPG background resisted cell attachment whereas high density cell attachment was observed on the peptide spots, resulting in high-contrast cell microarrays. We also demonstrated single-step, in situ functionalization of the HPG coatings by printing periodate and peptide concurrently. Our results demonstrate the effectiveness of antifouling and functionalized HPG graft polymer coatings and establish their use in microarray applications for the first time.

  8. Determination of Organotin Structures in Antifouling Coatings by Mossbauer Spectroscopic Techniques.

    DTIC Science & Technology

    1977-06-24

    are related to the molecular geometry. The Mossbauer parameters for organotin polymers used in antifouling coatings and conventional coating...In characterizing the leaching properties of antifouling coatings containing organotin compounds, it has become necessary to determine the structure...formulations containing organotin compounds have been obtained. The quadrupole splitting and rho value in these cases are sensitive to structural changes which

  9. Long-lasting Antifouling Coating from Multi-Armed Polymer

    PubMed Central

    Mizrahi, Boaz; Khoo, Xiaojuan; Chaing, Homer H.; Sher, Katalina J.; Feldman, Rose G.; Lee, Jung-Jae; Irusta, Silvia; Kohane, Daniel S.

    2013-01-01

    We describe a new antifouling surface coating, based on aggregation of a short amphiphilic four-armed PEG-dopamine polymer into particles, and on surface binding by catechol chemistry. An unbroken and smooth polymeric coating layer with an average thickness of approximately 4 microns was formed on top of titanium oxide surfaces by a single step reaction. Coatings conferred excellent resistance to protein adhesion. Cell attachment was completely prevented for at least eight weeks, although the membranes themselves did not appear to be intrinsically cytotoxic. When linear PEG or four-armed PEG of higher molecular weight were used, the resulting coatings were inferior in thickness and in preventing protein adhesion. This coating method has potential applicability for biomedical devices susceptible to fouling after implantation. PMID:23855875

  10. Anti-fouling Coatings of Poly(dimethylsiloxane) Devices for Biological and Biomedical Applications.

    PubMed

    Zhang, Hongbin; Chiao, Mu

    Fouling initiated by nonspecific protein adsorption is a great challenge in biomedical applications, including biosensors, bioanalytical devices, and implants. Poly(dimethylsiloxane) (PDMS), a popular material with many attractive properties for device fabrication in the biomedical field, suffers serious fouling problems from protein adsorption due to its hydrophobic nature, which limits the practical use of PDMS-based devices. Effort has been made to develop biocompatible materials for anti-fouling coatings of PDMS. In this review, typical nonfouling materials for PDMS coatings are introduced and the associated basic anti-fouling mechanisms, including the steric repulsion mechanism and the hydration layer mechanism, are described. Understanding the relationships between the characteristics of coating materials and the accompanying anti-fouling mechanisms is critical for preparing PDMS coatings with desirable anti-fouling properties.

  11. Entrapment of subtilisin in ceramic sol-gel coating for antifouling applications.

    PubMed

    Regina, Viduthalai Rasheedkhan; Søhoel, Helmer; Lokanathan, Arcot Raghupathi; Bischoff, Claus; Kingshott, Peter; Revsbech, Niels Peter; Meyer, Rikke Louise

    2012-11-01

    Enzymes with antifouling properties are of great interest in developing nontoxic antifouling coatings. A bottleneck in developing enzyme-based antifouling coatings is to immobilize the enzyme in a suitable coating matrix without compromising its activity and stability. Entrapment of enzymes in ceramics using the sol-gel method is known to have several advantages over other immobilization methods. The sol-gel method can be used to make robust coatings, and the aim of this study was to explore if sol-gel technology can be used to develop robust coatings harboring active enzymes for antifouling applications. We successfully entrapped a protease, subtilisin (Savinase, Novozymes), in a ceramic coating using a sol-gel method. The sol-gel formulation, when coated on a stainless steel surface, adhered strongly and cured at room temperature in less than 8 h. The resultant coating was smoother and less hydrophobic than stainless steel. Changes in the coating's surface structure, thickness and chemistry indicate that the coating undergoes gradual erosion in aqueous medium, which results in release of subtilisin. Subtilisin activity in the coating increased initially, and then gradually decreased. After 9 months, 13% of the initial enzyme activity remained. Compared to stainless steel, the sol-gel-coated surfaces with active subtilisin were able to reduce bacterial attachment of both Gram positive and Gram negative bacteria by 2 orders of magnitude. Together, our results demonstrate that the sol-gel method is a promising coating technology for entrapping active enzymes, presenting an interesting avenue for enzyme-based antifouling solutions.

  12. Microencapsulation of Biocides for Reduced Copper, Long-life Antifouling Coatings

    DTIC Science & Technology

    2007-02-01

    together with Microtek produce microencapsulated DCOIT. Laboratory facilities equipped to produce from 100g – 500kg batches of microcapsules . These...FINAL REPORT Microencapsulation of Biocides for Reduced Copper, Long-life Antifouling Coatings ESTCP Project WP-0306 FEBRUARY 2007...octyl-4-isothi azolin-3-one (DCOIT) hns been microencapsulated nnd incorporated into collUllercially relevanl AF coatings. Re•ulls demon•ll’ntt long

  13. XRF measurements of tin, copper and zinc in antifouling paints coated on leisure boats.

    PubMed

    Ytreberg, Erik; Bighiu, Maria Alexandra; Lundgren, Lennart; Eklund, Britta

    2016-06-01

    Tributyltin (TBT) and other organotin compounds have been restricted for use on leisure boats since 1989 in the EU. Nonetheless, release of TBT is observed from leisure boats during hull maintenance work, such as pressure hosing. In this work, we used a handheld X-ray Fluorescence analyser (XRF) calibrated for antifouling paint matrixes to measure tin, copper and zinc in antifouling paints coated on leisure boats in Sweden. Our results show that over 10% of the leisure boats (n = 686) contain >400 μg/cm(2) of tin in their antifouling coatings. For comparison, one layer (40 μm dry film) of a TBT-paint equals ≈ 800 μg Sn/cm(2). To our knowledge, tin has never been used in other forms than organotin (OT) in antifouling paints. Thus, even though the XRF analysis does not provide any information on the speciation of tin, the high concentrations indicate that these leisure boats still have OT coatings present on their hull. On several leisure boats we performed additional XRF measurements by progressively scraping off the top coatings and analysing each underlying layer. The XRF data show that when tin is detected, it is most likely present in coatings close to the hull with several layers of other coatings on top. Thus, leaching of OT compounds from the hull into the water is presumed to be negligible. The risk for environmental impacts arises during maintenance work such as scraping, blasting and high pressure hosing activities. The data also show that many boat owners apply excessive paint layers when following paint manufacturers recommendations. Moreover, high loads of copper were detected even on boats sailing in freshwater, despite the more than 20 year old ban, which poses an environmental risk that has not been addressed until now.

  14. Bioassays and selected chemical analysis of biocide-free antifouling coatings.

    PubMed

    Watermann, B T; Daehne, B; Sievers, S; Dannenberg, R; Overbeke, J C; Klijnstra, J W; Heemken, O

    2005-09-01

    Over the years several types of biocide-free antifouling paints have entered the market. The prohibition of biocidal antifouling paints in special areas of some European countries such as Sweden, Denmark and Germany has favoured the introduction of these paints to the market. Several types of biocide-free antifouling paints were subjected to bioassays and selected chemical analysis of leachate and incorporated substances. Both non-eroding coatings (silicones, fibre coats, epoxies, polyurethane, polyvinyl) and eroding coatings (SPCs, ablative) were tested to exclude the presence of active biocides and dangerous compounds. The paints were subjected to the luminescent bacteria test and the cypris larvae settlement assay, the latter delivering information on toxicity as well as on efficacy. The following chemical analyses of selected compounds of dry-film were performed: The results of the bioassays indicated that none of the coatings analysed contained leachable biocides. Nevertheless, some products contained or leached dangerous compounds. The analyses revealed leaching of nonylphenol (up to 74.7 ng/cm2/d after 48 h) and bisphenol A (up to 2.77 ng/cm2/d after 24 h) from epoxy resins used as substitutes for antifouling paints. The heavy metal, zinc, was measured in dry paint film in quantities up to 576,000 ppm in erodable coatings, not incorporated as a biocide but to control the rate of erosion. Values for TBT in silicone elutriates were mostly below the detection limit of 0.005 mg/kg. Values for DBT ranged between <0.005 and 6.28 mg/kg, deriving from catalysts used as curing agents. Some biocide-free paints contained leachable, toxic and dangerous compounds in the dry film, some of which may act as substitutes for biocides or are incorporated as plasticizers or catalysts. Implications to environmental requirements and legislation are discussed.

  15. Bio-inspired self-cleaning PAAS hydrogel released coating for marine antifouling.

    PubMed

    Xue, Lili; Lu, Xili; Wei, Huan; Long, Ping; Xu, Jina; Zheng, Yufeng

    2014-05-01

    In this paper, an antifouling hydrogel coating of slippery hydrogel-released hydrous surface (SHRHS) with the self-cleaning ability of oil-resistance and self-regeneration characters was designed. A physical blending method of loading Sodium polyacrylate (PAAS) powder into the organic silicon resin was employed to prepare the SHRHS coating. The oil-resistance of the intact and scratch SHRHS coatings was performed by time-sequence images of washing dyed beef tallow stain away. The results showed that the SHRHS coating has the greater ability of stain removal. The concentration of Na+ ions released from PAAS hydrogel on the surface of the SHRHS coating was investigated by ion chromatograph (IC). The results revealed that the coating had the ability of self-regeneration by PAAS hydrogel continuously peeling. The biomass of two marine microalgae species, Nitzschia closterium f. minutissima and Navicula climacospheniae Booth attached on the SHRHS was investigated using UV-Visible Spectrophotometer (UV) and Scanning electron microscopy (SEM). The results showed that the microalgaes attached a significantly lower numbers on the SHRHS in comparison with the organic silicon coating. In order to confirm the antifouling ability of the SHRHS coating, the field trials were carried out for 12weeks. It showed that the SHRHS may provide an effective attachment resistance to reduce biofouling.

  16. Environmentally benign sol-gel antifouling and foul-releasing coatings.

    PubMed

    Detty, Michael R; Ciriminna, Rosaria; Bright, Frank V; Pagliaro, Mario

    2014-02-18

    Biofouling on ships and boats, characterized by aquatic bacteria and small organisms attaching to the hull, is an important global issue, since over 80000 tons of antifouling paint is used annually. This biofilm, which can form in as little as 48 hours depending on water temperature, increases drag on watercraft, which greatly reduces their fuel efficiency. In addition, biofouling can lead to microbially induced corrosion (MIC) due to H2S formed by the bacteria, especially sulfate-reducing bacteria. When the International Maritime Organization (IMO) international convention banned the use of effective but environmentally damaging coatings containing tributyl tin in 2008, the development of clean and effective antifouling systems became more important than ever. New nonbiocidal coatings are now in high demand. Scientists have developed new polymers, materials, and biocides, including new elastomeric coatings that they have obtained by improving the original silicone (polydimethylsiloxane) formulation patented in 1975. However, the high cost of silicones, especially of fluoropolymer-modified silicones, has generally prevented their large-scale diffusion. In 2009, traditional antifouling coatings using cuprous oxide formulated in copolymer paints still represented 95% of the global market volume of anti-fouling paints. The sol-gel nanochemistry approach to functional materials has emerged as an attractive candidate for creating low fouling surfaces due to the unique structure and properties of silica-based coatings and of hybrid inorganic-organic silicas in particular. Sol-gel formulations easily bind to all types of surfaces, such as steel, fiberglass, aluminum, and wood. In addition, they can cure at room temperature and form thin glassy coatings that are markedly different from thick silicone elastomeric foul-releasing coatings. Good to excellent performance against biofouling, low cure temperatures, enhanced and prolonged chemical and physical stability, ease of

  17. Multivalent anchored and crosslinked hyperbranched polyglycerol monolayers as antifouling coating for titanium oxide surfaces.

    PubMed

    Wei, Qiang; Krysiak, Stefanie; Achazi, Katharina; Becherer, Tobias; Noeske, Paul-Ludwig Michael; Paulus, Florian; Liebe, Hendrik; Grunwald, Ingo; Dernedde, Jens; Hartwig, Andreas; Hugel, Thorsten; Haag, Rainer

    2014-10-01

    A set of new catecholic monolayer coatings was developed to improve the antifouling performance of TiO2 surfaces. To solve the problem of the weak charge-transfer interaction between a single catechol anchor and TiO2, multiple catechol groups were combined with hyperbranched polyglycerol (hPG) which is a distinct dendritic scaffold that exposes its multivalent anchor groups on the surface. Thus, multivalent catecholic hPGs can be easily prepared for surface modification. The immobilization of the compounds was monitored by quartz crystal microbalance with dissipation monitoring. Surface properties of the coatings were analyzed by water contact angle, X-ray photoelectron spectroscopy, and atomic force microscopy. The antifouling ability and stability were investigated by protein adsorption and cell adhesion. By increasing the number of catechol groups on the hPG scaffold, the stability and surface coverage could be significantly enhanced. Moreover, the inner-layer crosslinking of the coatings by grafting and initiating vinyl groups clearly improved their long-term stability. As a result, hPG with a catecholic functional degree of 10% (hPG-Cat10) and hPG with both catecholic and vinylic functional degree of 5% (hPG-Cat5-V5) were identified as the best catecholic hPGs to prepare bioinert and stable monolayer coatings on TiO2.

  18. Antifouling Coatings Influence both Abundance and Community Structure of Colonizing Biofilms: a Case Study in the Northwestern Mediterranean Sea

    PubMed Central

    Camps, Mercedes; Barani, Aude; Gregori, Gérald; Bouchez, Agnès; Le Berre, Brigitte; Bressy, Christine; Blache, Yves

    2014-01-01

    When immersed in seawater, substrates are rapidly colonized by both micro- and macroorganisms. This process is responsible for important economic and ecological prejudices, particularly when related to ship hulls or aquaculture nets. Commercial antifouling coatings are supposed to reduce biofouling, i.e., micro- and macrofoulers. In this study, biofilms that primarily settled on seven different coatings (polyvinyl chloride [PVC], a fouling release coating [FRC], and five self-polishing copolymer coatings [SPC], including four commercial ones) were quantitatively studied, after 1 month of immersion in summer in the Toulon Bay (Northwestern Mediterranean Sea, France), by using flow cytometry (FCM), microscopy, and denaturing gradient gel electrophoresis. FCM was used after a pretreatment to separate cells from the biofilm matrix, in order to determine densities of heterotrophic bacteria, picocyanobacteria, and pico- and nanoeukaryotes on these coatings. Among diatoms, the only microphytobenthic class identified by microscopy, Licmophora, Navicula, and Nitzschia were determined to be the dominant taxa. Overall, biocide-free coatings showed higher densities than all other coatings, except for one biocidal coating, whatever the group of microorganisms. Heterotrophic bacteria always showed the highest densities, and diatoms showed the lowest, but the relative abundances of these groups varied depending on the coating. In particular, the copper-free SPC failed to prevent diatom settlement, whereas the pyrithione-free SPC exhibited high picocyanobacterial density. These results highlight the interest in FCM for antifouling coating assessment as well as specific selection among microbial communities by antifouling coatings. PMID:24907329

  19. Antifouling coating of cellulose acetate thin films with polysaccharide multilayers.

    PubMed

    Mohan, Tamilselvan; Kargl, Rupert; Tradt, Karin Eva; Kulterer, Martin R; Braćić, Matej; Hribernik, Silvo; Stana-Kleinschek, Karin; Ribitsch, Volker

    2015-02-13

    In this investigation, partially deacetylated cellulose acetate (DCA) thin films were prepared and modified with hydrophilic polysaccharides with the layer-by-layer (LbL) technique. As polysaccharides, chitosan (CHI) and carboxymethyl cellulose (CMC) were used. DCA thin films were manufactured by exposing spin coated cellulose acetate to potassium hydroxide solutions for various times. The deacetylation process was monitored by attenuated total reflectance-infrared spectroscopy, film thickness and static water contact angle measurements. A maximum of three bilayers was created from the alternating deposition of CHI and CMC on the DCA films under two different conditions namely constant ionic strengths and varying pH values of the CMC solutions. Precoatings of CMC at pH 2 were used as a base layer. The sequential deposition of CMC and CHI was investigated with a quartz crystal microbalance with dissipation, film thickness, static water contact angle and atomic force microscopy (AFM) measurements. The versatility and applicability of the developed functional coatings was shown by removing the multilayers by rinsing with mixtures containing HCl/NaCl. The developed LbL coatings are used for studying the fouling behavior of bovine serum albumin (BSA).

  20. Brush-like polycarbonates containing dopamine, cations, and PEG providing a broad-spectrum, antibacterial, and antifouling surface via one-step coating.

    PubMed

    Yang, Chuan; Ding, Xin; Ono, Robert J; Lee, Haeshin; Hsu, Li Yang; Tong, Yen Wah; Hedrick, James; Yang, Yi Yan

    2014-11-19

    An antibacterial and antifouling surface is obtained by simple one-step immersion of a catheter surface with brush-like polycarbonates containing pendent adhesive dopamine, antifouling polyethylene glycol (PEG), and antibacterial cations. This coating demonstrates excellent antibacterial and antifouling activities against both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria, proteins, and platelets, good stability under simulated blood-flow conditions, and no toxicity.

  1. Preparation of antifouling poly(vinylidene fluoride) membranes via different coating methods using a zwitterionic copolymer

    NASA Astrophysics Data System (ADS)

    Ma, Wenzhong; Rajabzadeh, Saeid; Matsuyama, Hideto

    2015-12-01

    To reduce the fouling resistance of poly(vinylidene fluoride) membranes, a copolymer of 2-methacryloyloxyethyl phosphorylcholine (MPC) and n-butyl methacrylate (BMA) [poly(MPC-co-BMA)] was coated on a membrane and into its pores from an aqueous solution using two different methods, the immersion and flow-through methods. The effects of poly(MPC-co-BMA) coating on the water flux, surface morphology, and fouling propensity of three types of commercial ultrafiltration membranes with molecular-weight cutoffs ranging from 50 to 250 kDa were investigated. The fouling resistances of modified membranes to bovine serum albumin were compared to those of the unmodified membranes. The evaluation of X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy of the modified membranes confirmed that poly(MPC-co-BMA) was coated on the membrane surfaces. Although both modification methods effectively prevented protein fouling, the flow-through coating method demonstrated a better antifouling propensity. The coated copolymer stability results indicated that the coated copolymer layer on the membrane surface using both coating methods was quite stable even after ultrasonic treatment.

  2. Turbulent boundary layer measurements over flat surfaces coated by nanostructured marine antifoulings

    NASA Astrophysics Data System (ADS)

    Ünal, Uğur Oral; Ünal, Burcu; Atlar, Mehmet

    2012-06-01

    Whilst recent developments of nanotechnology are being exploited by chemists and marine biologists to understand how the completely environmentally friendly foul release coatings can control marine biofouling and how they can be developed further, the understanding of the hydrodynamic performances of these new generation coatings is being overlooked. This paper aims to investigate the relative boundary layer, roughness and drag characteristics of some novel nanostructured coatings, which were developed through a multi-European and multi-disciplined collaborative research project AMBIO (2010), within the framework of turbulent flows over rough surfaces. Zero-pressure-gradient, turbulent boundary layer flow measurements were conducted over flat surfaces coated with several newly developed nanostructured antifouling paints, along with some classic reference surfaces and a state-of-the-art commercial coating, in the Emerson Cavitation Tunnel (ECT) of Newcastle University. A large flat plane test bed that included interchangeable flat test sections was used for the experiments. The boundary layer data were collected with the aid of a two-dimensional DANTEC Laser Doppler Velocimetry (LDV) system. These measurements provided the main hydrodynamic properties of the newly developed nanostructured coatings including local skin friction coefficients, roughness functions and Reynolds stresses. The tests and subsequent analysis indicated the exceptionally good frictional properties of all coatings tested, in particular, the drag benefit of some new nanostructured coatings in the Reynolds number range investigated. The rapidly decreasing roughness function trends of AKZO19 and AKZO20 as the ks^{ + } increases were remarkable along with the dissimilar roughness function character of all tested coatings to the well-known correlation curves warranting further research at higher Reynolds numbers. The wall similarity concept for the Reynolds stresses was only validated for the

  3. Anti-fouling poly(2-hydoxyethyl methacrylate) surface coatings with specific bacteria recognition capabilities

    NASA Astrophysics Data System (ADS)

    Mrabet, Bechir; Nguyen, Minh Ngoc; Majbri, Aymen; Mahouche, Samia; Turmine, Mireille; Bakhrouf, Amina; Chehimi, Mohamed M.

    2009-08-01

    Poly(2-hydroxyethyl methacrylate), PHEMA, brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) on silanized glass slides bearing grafted initiators. High resolution X-ray photoelectron spectroscopy (XPS) highlighted the surface chemical changes of the glass slides upon silanization and surface-confined ATRP of HEMA. Particularly, the initiator sites from the silane were detected by their bromine Br3d core electron peak whilst the O/C atomic ratios and the high resolution C1s region of the glass-PHEMA hybrids are comparable to those of pure PHEMA, thus confirming that the PHEMA chains have indeed attached to the surface. The glass-PHEMA hybrids were found to behave as anti-fouling ultrathin coatings as they resisted non-specific Salmonella typhimurium bacterial adhesion. This behaviour is driven by the hydrophilic properties of the glass-PHEMA hybrids which were assessed by contact angle measurements. In contrast, after activation of PHEMA brushes by S.typhimurium antibodies through the trichlorotriazine coupling procedure, the bacteria specifically and strongly attached to the PHEMA-coated glass slides as judged from optical microscope observation.

  4. Investigation of the role of hydrophilic chain length in amphiphilic perfluoropolyether/poly(ethylene glycol) networks: towards high-performance antifouling coatings

    SciTech Connect

    Wang, Yapei; Pitet, Louis M.; Finlay, John A.; Brewer, Lenora H.; Cone, Gemma; Betts, Douglas E.; Callow, Maureen E.; Callow, James A.; Wendt, Dean E.; Hillmyer, Marc A.; DeSimone, Joseph M.

    2013-03-07

    The facile preparation of amphiphilic network coatings having a hydrophobic dimethacryloxy-functionalized perfluoropolyether (PFPE-DMA; M{sub w} = 1500 g mol{sup -1}) crosslinked with hydrophilic monomethacryloxy functionalized poly(ethylene glycol) macromonomers (PEG-MA; M{sub w} = 300, 475, 1100 g mol{sup -1}), intended as non-toxic high-performance marine coatings exhibiting antifouling characteristics is demonstrated. The PFPE-DMA was found to be miscible with the PEG-MA. Photo-cured blends of these materials containing 10 wt% of PEG-MA oligomers did not swell significantly in water. PFPE-DMA crosslinked with the highest molecular weight PEG oligomer (ie PEG1100) deterred settlement (attachment) of algal cells and cypris larvae of barnacles compared to a PFPE control coating. Dynamic mechanical analysis of these networks revealed a flexible material. Preferential segregation of the PEG segments at the polymer/air interface resulted in enhanced antifouling performance. The cured amphiphilic PFPE/PEG films showed decreased advancing and receding contact angles with increasing PEG chain length. In particular, the PFPE/PEG1100 network had a much lower advancing contact angle than static contact angle, suggesting that the PEG1100 segments diffuse to the polymer/water interface quickly. The preferential interfacial aggregation of the larger PEG segments enables the coating surface to have a substantially enhanced resistance to settlement of spores of the green seaweed Ulva, cells of the diatom Navicula and cypris larvae of the barnacle Balanus amphitrite as well as low adhesion of sporelings (young plants) of Ulva, adhesion being lower than to a polydimethyl elastomer, Silastic T2.

  5. Advanced Coats' disease.

    PubMed Central

    Haik, B G

    1991-01-01

    Advanced Coats' disease and retinoblastoma can both present with the triad of a retinal detachment, the appearance of a subretinal mass, and dilated retinal vessels. Thus, even the most experienced observer may not be able to differentiate these entities on ophthalmoscopic findings alone. Coats' disease is the most common reason for which eyes are enucleated with the misdiagnosis of retinoblastoma. Ultrasonography is the auxiliary diagnostic test most easily incorporated into the clinical examination, and can be utilized repeatedly without biologic tissue hazard. Ultrasonically identifiable features allowing differentiation between Coats' disease and retinoblastoma include the topography and character of retinal detachment and presence or absence of subretinal calcifications. Ultrasonography is of lesser use in poorly calcified retinoblastoma and in detecting optic nerve or extraocular extension in heavily calcified retinoblastoma. CT is perhaps the single most valuable test because of its ability to: (a) delineate intraocular morphology, (b) quantify subretinal densities, (c) identify vascularities within the subretinal space through the use of contrast enhancement, and (d) detected associated orbital or intracranial abnormalities. Optimal computed tomographic studies, however, require multiple thin slices both before and after contrast introduction and expose the child to low levels of radiation if studies are repeated periodically. MR imaging is valuable for its multiplanar imaging capabilities, its superior contrast resolution, and its ability to provide insights into the biochemical structure and composition of tissues. It is limited in its ability to detect calcium, which is the mainstay of ultrasonic and CT differentiation. Aqueous LDH and isoenzyme levels were not valuable in distinguishing between Coats' disease and retinoblastoma. The value of aqueous NSE levels in the differentiation of advanced Coats' disease and exophytic retinoblastoma deserves

  6. Development of FDR-AF (Frictional Drag Reduction Anti-Fouling) Marine Coating

    NASA Astrophysics Data System (ADS)

    Lee, Inwon; Park, Hyun; Chun, Ho Hwan; GCRC-SOP Team

    2013-11-01

    In this study, a novel skin-friction reducing marine paint has been developed by mixing fine powder of PEO(PolyEthyleneOxide) with SPC (Self-Polishing Copolymer) AF (Anti-Fouling) paint. The PEO is well known as one of drag reducing agent to exhibit Toms effect, the attenuation of turbulent flows by long chain polymer molecules in the near wall region. The frictional drag reduction has been implemented by injecting such polymer solutions to liquid flows. However, the injection holes have been a significant obstacle to marine application. The present PEO-containing marine paint is proposed as an alternative to realize Toms effect without any hole on the ship surface. The erosion mechanism of SPC paint resin and the subsequent dissolution of PEO enable the controlled release of PEO solution from the coating. Various tests such as towing tank drag measurement of flat plate and turbulence measurement in circulating water tunnel demonstrated over 10% frictional drag reduction compared with conventional AF paint. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) through GCRC-SOP(No. 2011-0030013).

  7. Antifouling coating with controllable and sustained silver release for long-term inhibition of infection and encrustation in urinary catheters.

    PubMed

    Wang, Rong; Neoh, Koon Gee; Kang, En-Tang; Tambyah, Paul Anantharajah; Chiong, Edmund

    2015-04-01

    Urinary tract infections constitute a large proportion of nosocomial infections, and the urinary catheter is the most important predisposing factor. Encrustation induced by urease-producing uropathogens like Proteus mirabilis causes further complications. In the present work, a strategy for controllable and sustained release of silver over several weeks has been developed for combating bacterial infection and encrustation in urinary devices. Silver nanoparticles (AgNPs) were first immobilized on polydopamine (PDA) pre-treated silicone catheter surface and this was followed by another PDA coating. The number of AgNP-PDA bilayers could be manipulated to control the amount of silver loaded and its subsequent release. Poly(sulfobetaine methacrylate-co-acrylamide) was then grafted to provide an antifouling outer layer, and to ensure free diffusion of Ag from the surface. The micron-scale combination of an antifouling coating with AgNP-PDA bilayers reduced colonization of the urinary catheter by uropathogens by approximately two orders of magnitude. With one and two AgNP-PDA bilayers, the coated catheter could resist encrustation for 12 and 45 days, respectively, compared with approximately 6 days with the Dover™ silver-coated catheter. Such anti-infective and anti-encrustation catheters can potentially have a large impact on reducing patient morbidity and healthcare expenditure.

  8. Sunlight-Sensitive Anti-Fouling Nanostructured TiO2 coated Cu Meshes for Ultrafast Oily Water Treatment

    PubMed Central

    Liu, HaoRan; Raza, Aikifa; Aili, Abulimiti; Lu, JinYou; AlGhaferi, Amal; Zhang, TieJun

    2016-01-01

    Nanostructured materials with desired wettability and optical property can play an important role in reducing the energy consumption of oily water treatment technologies. For effective oily water treatment, membrane materials with high strength, sunlight-sensitive anti-fouling, relative low fabrication cost, and controllable wettability are being explored. In the proposed oily water treatment approach, nanostructured TiO2-coated copper (TNS-Cu) meshes are used. These TNS-Cu meshes exhibit robust superhydrophilicity and underwater oleophobicity (high oil intrusion pressure) as well as excellent chemical and thermal stability (≈250 °C). They have demonstrated high separation efficiency (oil residue in the filtrate ≤21.3 ppm), remarkable filtration flux (≥400 kL h−1 m−2), and sunlight-sensitive anti-fouling properties. Both our theoretical analysis and experimental characterization have confirmed the enhanced light absorption property of TNS-Cu meshes in the visible region (40% of the solar spectrum) and consequently strong anti-fouling capability upon direct solar light illumination. With these features, the proposed approach promises great potential in treating produced oily wastewater from industry and daily life. PMID:27160349

  9. Sunlight-Sensitive Anti-Fouling Nanostructured TiO2 coated Cu Meshes for Ultrafast Oily Water Treatment

    NASA Astrophysics Data System (ADS)

    Liu, Haoran; Raza, Aikifa; Aili, Abulimiti; Lu, Jinyou; Alghaferi, Amal; Zhang, Tiejun

    2016-05-01

    Nanostructured materials with desired wettability and optical property can play an important role in reducing the energy consumption of oily water treatment technologies. For effective oily water treatment, membrane materials with high strength, sunlight-sensitive anti-fouling, relative low fabrication cost, and controllable wettability are being explored. In the proposed oily water treatment approach, nanostructured TiO2-coated copper (TNS-Cu) meshes are used. These TNS-Cu meshes exhibit robust superhydrophilicity and underwater oleophobicity (high oil intrusion pressure) as well as excellent chemical and thermal stability (≈250 °C). They have demonstrated high separation efficiency (oil residue in the filtrate ≤21.3 ppm), remarkable filtration flux (≥400 kL h‑1 m‑2), and sunlight-sensitive anti-fouling properties. Both our theoretical analysis and experimental characterization have confirmed the enhanced light absorption property of TNS-Cu meshes in the visible region (40% of the solar spectrum) and consequently strong anti-fouling capability upon direct solar light illumination. With these features, the proposed approach promises great potential in treating produced oily wastewater from industry and daily life.

  10. Sunlight-Sensitive Anti-Fouling Nanostructured TiO2 coated Cu Meshes for Ultrafast Oily Water Treatment.

    PubMed

    Liu, HaoRan; Raza, Aikifa; Aili, Abulimiti; Lu, JinYou; AlGhaferi, Amal; Zhang, TieJun

    2016-05-10

    Nanostructured materials with desired wettability and optical property can play an important role in reducing the energy consumption of oily water treatment technologies. For effective oily water treatment, membrane materials with high strength, sunlight-sensitive anti-fouling, relative low fabrication cost, and controllable wettability are being explored. In the proposed oily water treatment approach, nanostructured TiO2-coated copper (TNS-Cu) meshes are used. These TNS-Cu meshes exhibit robust superhydrophilicity and underwater oleophobicity (high oil intrusion pressure) as well as excellent chemical and thermal stability (≈250 °C). They have demonstrated high separation efficiency (oil residue in the filtrate ≤21.3 ppm), remarkable filtration flux (≥400 kL h(-1 )m(-2)), and sunlight-sensitive anti-fouling properties. Both our theoretical analysis and experimental characterization have confirmed the enhanced light absorption property of TNS-Cu meshes in the visible region (40% of the solar spectrum) and consequently strong anti-fouling capability upon direct solar light illumination. With these features, the proposed approach promises great potential in treating produced oily wastewater from industry and daily life.

  11. Antifouling and Antibacterial Multifunctional Polyzwitterion/Enzyme Coating on Silicone Catheter Material Prepared by Electrostatic Layer-by-Layer Assembly.

    PubMed

    Vaterrodt, Anne; Thallinger, Barbara; Daumann, Kevin; Koch, Dereck; Guebitz, Georg M; Ulbricht, Mathias

    2016-02-09

    The formation of bacterial biofilms on indwelling medical devices generally causes high risks for adverse complications such as catheter-associated urinary tract infections. In this work, a strategy for synthesizing innovative coatings of poly(dimethylsiloxane) (PDMS) catheter material, using layer-by-layer assembly with three novel functional polymeric building blocks, is reported, i.e., an antifouling copolymer with zwitterionic and quaternary ammonium side groups, a contact biocidal derivative of that polymer with octyl groups, and the antibacterial hydrogen peroxide (H2O2) producing enzyme cellobiose dehydrogenase (CDH). CDH oxidizes oligosaccharides by transferring electrons to oxygen, resulting in the production of H2O2. The design and synthesis of random copolymers which combine segments that have antifouling properties by zwitterionic groups and can be used for electrostatically driven layer-by-layer (LbL) assembly at the same time were based on the atom-transfer radical polymerization of dimethylaminoethyl methacrylate and subsequent partial sulfobetainization with 1,3-propane sultone followed by quaternization with methyl iodide only or octyl bromide and thereafter methyl iodide. The alternating multilayer systems were formed by consecutive adsorption of the novel polycations with up to 50% zwitterionic groups and of poly(styrenesulfonate) as the polyanion. Due to its negative charge, enzyme CDH was also firmly embedded as a polyanionic layer in the multilayer system. This LbL coating procedure was first performed on prefunctionalized silicon wafers and studied in detail with ellipsometry as well as contact angle (CA) and zetapotential (ZP) measurements before it was transferred to prefunctionalized PDMS and analyzed by CA and ZP measurements as well as atomic force microscopy. The coatings comprising six layers were stable and yielded a more neutral and hydrophilic surface than did PDMS, the polycation with 50% zwitterionic groups having the largest

  12. Fabrication of FDTS-modified PDMS-ZnO nanocomposite hydrophobic coating with anti-fouling capability for corrosion protection of Q235 steel.

    PubMed

    Arukalam, Innocent O; Oguzie, Emeka E; Li, Ying

    2016-12-15

    Perfluorodecyltrichlorosilane-based poly(dimethylsiloxane)-ZnO (FDTS-based PDMS-ZnO) nanocomposite coating with anti-corrosion and anti-fouling capabilities has been prepared using a one-step fabrication technique. XPS analysis and contact angle measurements showed the fluorine content to increase, while the hydrophobicity of the coatings decreased with addition of FDTS. XRD analysis revealed existence of ZnO nanoparticles of dimensions ranging from 11.45 to 93.01nm on the surface of coatings, with the mean particle size decreasing with FDTS addition, and was confirmed by SEM and TEM observations. Interestingly, the anti-corrosion performance and mechanical properties of the coatings increased remarkably on addition of FDTS. Indeed, the observed low adhesion strength, surface energies and the outstanding anti-corrosive properties imply that the obtained coating would be useful in anti-fouling applications.

  13. Advanced Coating Removal Techniques

    NASA Technical Reports Server (NTRS)

    Seibert, Jon

    2006-01-01

    An important step in the repair and protection against corrosion damage is the safe removal of the oxidation and protective coatings without further damaging the integrity of the substrate. Two such methods that are proving to be safe and effective in this task are liquid nitrogen and laser removal operations. Laser technology used for the removal of protective coatings is currently being researched and implemented in various areas of the aerospace industry. Delivering thousands of focused energy pulses, the laser ablates the coating surface by heating and dissolving the material applied to the substrate. The metal substrate will reflect the laser and redirect the energy to any remaining protective coating, thus preventing any collateral damage the substrate may suffer throughout the process. Liquid nitrogen jets are comparable to blasting with an ultra high-pressure water jet but without the residual liquid that requires collection and removal .As the liquid nitrogen reaches the surface it is transformed into gaseous nitrogen and reenters the atmosphere without any contamination to surrounding hardware. These innovative technologies simplify corrosion repair by eliminating hazardous chemicals and repetitive manual labor from the coating removal process. One very significant advantage is the reduction of particulate contamination exposure to personnel. With the removal of coatings adjacent to sensitive flight hardware, a benefit of each technique for the space program is that no contamination such as beads, water, or sanding residue is left behind when the job is finished. One primary concern is the safe removal of coatings from thin aluminum honeycomb face sheet. NASA recently conducted thermal testing on liquid nitrogen systems and found that no damage occurred on 1/6", aluminum substrates. Wright Patterson Air Force Base in conjunction with Boeing and NASA is currently testing the laser remOval technique for process qualification. Other applications of liquid

  14. Rationally designed dual functional block copolymers for bottlebrush-like coatings: In vitro and in vivo antimicrobial, antibiofilm, and antifouling properties.

    PubMed

    Gao, Qiang; Yu, Meng; Su, Yajuan; Xie, Meihua; Zhao, Xin; Li, Peng; Ma, Peter X

    2017-01-25

    Numerous antimicrobial coatings have been developed for biomedical devices/implants, but few can simultaneously fulfill the requirements for antimicrobial and antifouling ability and biocompatibility. In this study, to develop an antimicrobial and antibiofilm surface coating, diblock amphiphilic molecules with antimicrobial and antifouling segments in a single chain were rationally designed and synthesized. Cationic antimicrobial polypeptides (AMP) were first synthesized by N-carboxyanhydride ring-opening polymerization (NCA-ROP). Heterofunctionalized poly(ethylene glycol) with different lengths (methacrylate-PEGn-tosyl, n=10/45/90) was synthesized and site-specifically conjugated with polypeptides to form diblock amphiphiles. Along with increased PEG chain length, hemolytic activity was considerably improved, and broad-spectrum antimicrobial activity is retained. Three MA-PEGn-b-AMP copolymers were further grafted onto the surface of silicone rubber (a commonly used catheter material) via plasma/UV-induced surface polymerizations to form a bottlebrush-like coating with excellent antimicrobial activity against several pathogenic bacteria (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus), and effectively prevent biofilm formation. This bottlebrush coating also greatly reduced protein adsorption and platelet adhesion, indicating its excellent antifouling ability. An in vitro cytotoxicity study also demonstrated that this coating is biocompatible with mammalian cells. After subcutaneous implantation of the materials in rats, we demonstrated that the g-PEG45-b-AMP bottlebrush coating exhibits significant anti-infective activity in vivo. Thus, this facilely synthesized PEGylated AMP bottlebrush coating is a feasible method to prevent biomedical devices-associated infections.

  15. Integrated antifouling and bactericidal polymer membranes through bioinspired polydopamine/poly(N-vinyl pyrrolidone) coating

    NASA Astrophysics Data System (ADS)

    Wang, Xianghong; Yuan, Shuaishuai; Shi, Dean; Yang, Yingkui; Jiang, Tao; Yan, Shunjie; Shi, Hengchong; Luan, Shifang; Yin, Jinghua

    2016-07-01

    Polypropylene (PP) non-woven has been widely used as wound dressing; however, the hydrophobic nature of PP can initiate bacterial attachment and subsequent biofilm formation. Herein, we propose a facile approach to functionalize PP non-woven with poly(ethylene glycol) (PEG) and poly(N-vinyl pyrrolidone)-iodine complex (PVP-I). PVP and PEG were successively tethered onto PP non-woven surface via versatile bioinspired dopamine (DA) chemistry, followed by complexing iodine with PVP moieties. It was demonstrated through the field emission scanning electron microscope (SEM) and spread plate method that the as-modified PP non-woven integrated both antifouling property of PEG for suppressing bacterial adhesion, and bactericidal property of PVP-I for killing the few adherent bacteria. Meanwhile, it could greatly resist platelet and red blood cell adhesion. The integrated antifouling and bactericidal PP non-woven surfaces might have great potential in various wound dressing applications.

  16. Surface anchored metal-organic frameworks as stimulus responsive antifouling coatings.

    PubMed

    Sancet, Maria Pilar Arpa; Hanke, Maximilian; Wang, Zhengbang; Bauer, Stella; Azucena, Carlos; Arslan, Hasan K; Heinle, Marita; Gliemann, Hartmut; Wöll, Christof; Rosenhahn, Axel

    2013-12-01

    Surface-anchored, crystalline and oriented metal organic frameworks (SURMOFs) have huge potential for biological applications due to their well-defined and highly-porous structure. In this work we describe a MOF-based, fully autonomous system, which combines sensing, a specific response, and the release of an antimicrobial agent. The Cu-containing SURMOF, Cu-SURMOF 2, is stable in artificial seawater and shows stimulus-responsive anti-fouling properties against marine bacteria. When Cobetia marina adheres on the SURMOF, the framework's response is lethal to the adhering microorganism. A thorough analysis reveals that this response is induced by agents secreted from the microbes after adhesion to the substrate, and includes a release of Cu ions resulting from a degradation of the SURMOF. The stimulus-responsive antifouling effect of Cu-SURMOF 2 demonstrates the first application of Cu-SURMOF 2 as autonomous system with great potential for further microbiological and cell culture applications.

  17. Comparison between polyethylene glycol and zwitterionic polymers as antifouling coatings on wearable devices for selective antigen capture from biological tissue.

    PubMed

    Robinson, Kye J; Coffey, Jacob W; Muller, David A; Young, Paul R; Kendall, Mark A F; Thurecht, Kristofer J; Grøndahl, Lisbeth; Corrie, Simon R

    2015-12-07

    Selective capture of disease-related proteins in complex biological fluids and tissues is an important aim in developing sensitive protein biosensors for in vivo applications. Microprojection arrays are biomedical devices whose mechanical and chemical properties can be tuned to allow efficient penetration of skin, coupled with highly selective biomarker capture from the complex biological environment of skin tissue. Herein, the authors describe an improved surface modification strategy to produce amine-modified polycarbonate arrays, followed by the attachment of an antifouling poly(sulfobetaine-methacrylate) (pSBMA) polymer or a linear polyethylene glycol (PEG) polymer of comparative molecular weight and hydrodynamic radius. Using a "grafting to" approach, pSBMA and linear PEG coatings yielded comparative antifouling behavior in single protein solutions, diluted plasma, or when applied to mouse flank skin penetrating into the vascularized dermal tissue. Interestingly, the density of immobilized immunoglobulin G (IgG) or bovine serum albumin protein on pSBMA surfaces was significantly higher than that on the PEG surfaces, while the nonspecific adsorption was comparable for each protein. When incubated in buffer or plasma solutions containing dengue non-structural protein 1 (NS1), anti-NS1-IgG-coated pSBMA surfaces captured significantly more NS1 in comparison to PEG-coated devices. Similarly, when wearable microprojection arrays were applied to the skin of dengue-infected mice using the same coatings, the pSBMA-coated devices showed significantly higher capture efficiency (>2-fold increase in signal) than the PEG-coated substrates, which showed comparative signal when applied to naïve mice. In conclusion, zwitterionic pSBMA polymers (of equivalent hydrodynamic radii to PEG) allowed detection of dengue NS1 disease biomarker in a preclinical model of dengue infection, showing significantly higher signal-to-noise ratio in comparison to the PEG controls. The results of

  18. Biomimetic PEG-catecholates for stabile antifouling coatings on metal surfaces: applications on TiO2 and stainless steel.

    PubMed

    Khalil, Faiza; Franzmann, Elisa; Ramcke, Julian; Dakischew, Olga; Lips, Katrin S; Reinhardt, Alexander; Heisig, Peter; Maison, Wolfgang

    2014-05-01

    Trimeric catecholates have been designed for the stable immobilization of effector molecules on metal surfaces. The design of these catecholates followed a biomimetic approach and was inspired by natural multivalent metal binders, such as mussel adhesion proteins (MAPs) and siderophores. Three catecholates have been conjugated to central scaffolds based on adamantyl or trisalkylmethyl core structures. The resulting triscatecholates have been immobilized on TiO2 and stainless steel. In a proof of concept study we have demonstrated the high stability of the resulting nanolayers at neutral and slightly acidic pH. Furthermore, polyethylene glycol (PEG) conjugates of our triscatecholates have been synthesized and were immobilized on TiO2 and stainless steel. The PEG coated surfaces showed excellent antifouling properties upon exposure to human blood and bacteria as demonstrated by fluorescence microscopy, ellipsometry and a bacterial assay with Staphylococcus epidermidis. In addition, our PEG-triscatecholates showed no cytotoxicity against bone-marrow stem cells on TiO2.

  19. Spatio-Temporal Variations of Marine Biofilm Communities Colonizing Artificial Substrata Including Antifouling Coatings in Contrasted French Coastal Environments.

    PubMed

    Briand, Jean-François; Barani, Aude; Garnier, Cédric; Réhel, Karine; Urvois, Félix; LePoupon, Christophe; Bouchez, Agnès; Debroas, Didier; Bressy, Christine

    2017-04-03

    Surface colonization in seawater first corresponds to the selection of specific microbial biofilm communities. By coupling flow cytometry, microscopy and high throughput sequencing (HTS, 454 pyrosequencing) with artificial surfaces and environmental analyses, we intend to identify the contribution of biofilm community drivers at two contrasted French sites, one temperate and eutrophic (Lorient, Atlantic coast) and the other at a mesotrophic but highly contaminated bay (Toulon, North-Western Mediterranean Sea). Microbial communities were shaped by high temperatures, salinity and lead at Toulon by but nutrients and DOC at Lorient. Coatings including pyrithione exhibited a significant decrease of their microbial densities except for nanoeukaryotes. Clustering of communities was mainly based on the surface type and secondly the site, whereas seasons appeared of less importance. The in-depth HTS revealed that γ- and α-proteobacteria, but also Bacteroidetes, dominated highly diversified bacterial communities with a relative low β-diversity. Sensitivity to biocides released by the tested antifouling coatings could be noticed at different taxonomic levels: the percentage of Bacteroidetes overall decreased with the presence of pyrithione, whereas the α/γ-proteobacteria ratio decreased at Toulon when increased at Lorient. Small diatom cells (Amphora and Navicula spp.) dominated on all surfaces, whereas site-specific sub-dominant taxa appeared clearly more sensitive to biocides. This overall approach exhibited the critical significance of surface characteristics in biofilm community shaping.

  20. Bubbles versus biofilms: a novel method for the removal of marine biofilms attached on antifouling coatings using an ultrasonically activated water stream

    NASA Astrophysics Data System (ADS)

    Salta, M.; Goodes, L. R.; Maas, B. J.; Dennington, S. P.; Secker, T. J.; Leighton, T. G.

    2016-09-01

    The accumulation of marine organisms on a range of manmade surfaces, termed biofouling, has proven to be the Achilles’ heel of the shipping industry. Current antifouling coatings, such as foul release coatings (FRCs), only partially inhibit biofouling, since biofilms remain a major issue. Mechanical ship hull cleaning is commonly employed to remove biofilms, but these methods tend to damage the antifouling coating and often do not result in full removal. Here, we report the effectiveness of biofilm removal from FRCs through a novel cleaning device that uses an ultrasonically activated stream (UAS). In this device, ultrasound enhances the cleaning properties of microbubbles in a freely flowing stream of water. The UAS was applied on two types of commercial FRCs which were covered with biofilm growth following twelve days immersion in the marine environment. Biofilm removal was quantified in terms of reduction in biovolume and surface roughness, both measured using an optical profilometer, which were then compared with similar measurements after cleaning with a non-ultrasonically activated water stream. It was found that the UAS significantly improves the cleaning capabilities of a water flow, up to the point where no detectable biofilm remained on the coating surfaces. Overall biofilm surface coverage was significantly lower on the FRC coatings cleaned with the UAS system when compared to the coatings cleaned with water or not cleaned at all. When biofilm biomass removal was investigated, the UAS system resulted in significantly lower biovolume values even when compared to the water cleaning treatment with biovolume values close to zero. Remarkably, the surface roughness of the coatings after cleaning with the UAS was found to be comparable to that of the blank, non-immersed coatings, illustrating that the UAS did not damage the coatings in the process. The data supporting this study are openly available from the University of Southampton repository at http

  1. Non-Leaching, Benign Antifouling Multilayer Polymer Coatings for Marine Applications

    DTIC Science & Technology

    2010-03-01

    oriented. It is caused by the accumulation and settlement of barnacles, macroalgae , microbial slimes, and other micro and macro scale organisms on man...on the experimental coatings was compared with the settlement rates of the controls. Barnacles are then cultivated to a mature size (over two to four...SABC Coatings After settling on the glass slides as described previously, barnacle cyprid larvae are cultivated for two to four months until they

  2. Antifouling coatings based on covalently cross-linked agarose film via thermal azide-alkyne cycloaddition.

    PubMed

    Xu, Li Qun; Pranantyo, Dicky; Neoh, Koon-Gee; Kang, En-Tang; Teo, Serena Lay-Ming; Fu, Guo Dong

    2016-05-01

    Coatings based on thin films of agarose-poly(ethylene glycol) (Agr-PEG) cross-linked systems are developed as environmentally-friendly and fouling-resistant marine coatings. The Agr-PEG cross-linked systems were prepared via thermal azide-alkyne cycloaddition (AAC) using azido-functionalized Agr (AgrAz) and activated alkynyl-containing poly(2-propiolamidoethyl methacrylate-co-poly(ethylene glycol)methyl ether methacrylate) P(PEMA-co-PEGMEMA) random copolymers as the precursors. The Agr-PEG cross-linked systems were further deposited onto a SS surface, pre-functionalized with an alkynyl-containing biomimetic anchor, dopamine propiolamide, to form a thin film after thermal treatment. The thin film-coated SS surfaces can effectively reduce the adhesion of marine algae and the settlement of barnacle cyprids. Upon covalent cross-linking, the covalently cross-linked Agr-PEG films coated SS surfaces exhibit good stability in flowing artificial seawater, and enhanced resistance to the settlement of barnacle cyprids, in comparison to that of the surfaces coated with physically cross-linked AgrAz films.

  3. Advanced thermal barrier coating systems

    NASA Technical Reports Server (NTRS)

    Dorfman, M. R.; Reardon, J. D.

    1985-01-01

    Current state-of-the-art thermal barrier coating (TBC) systems consist of partially stabilized zirconia coatings plasma sprayed over a MCrAlY bond coat. Although these systems have excellent thermal shock properties, they have shown themselves to be deficient for a number of diesel and aircraft applications. Two ternary ceramic plasma coatings are discussed with respect to their possible use in TBC systems. Zirconia-ceria-yttria (ZCY) coatings were developed with low thermal conductivities, good thermal shock resistance and improved resistance to vanadium containing environments, when compared to the baseline yttria stabilized zirconia (YSZ) coatings. In addition, dense zirconia-titania-yttria (ZTY) coatings were developed with particle erosion resistance exceeding conventional stabilized zirconia coatings. Both coatings were evaluated in conjunction with a NiCr-Al-Co-Y2O3 bond coat. Also, multilayer or hybrid coatings consisting of the bond coat with subsequent coatings of zirconia-ceria-yttria and zirconia-titania-yttria were evaluated. These coatings combine the enhanced performance characteristics of ZCY with the improved erosion resistance of ZTY coatings. Improvement in the erosion resistance of the TBC system should result in a more consistent delta T gradient during service. Economically, this may also translate into increased component life simply because the coating lasts longer.

  4. Comparison of anti-fouling surface coatings for applications in bacteremia diagnostics.

    PubMed

    Boardman, Anna K; Allison, Sandra; Sharon, Andre; Sauer-Budge, Alexis F

    2013-01-01

    To accurately diagnose microbial infections in blood, it is essential to recover as many microorganisms from a sample as possible. Unfortunately, recovering such microorganisms depends significantly on their adhesion to the surfaces of diagnostic devices. Consequently, we sought to minimize the adhesion of methicillin-sensitive Staphylococcus aureus (MSSA) to the surface of polypropylene- and acrylic-based bacteria concentration devices. These devices were treated with 11 different coatings having various charges and hydrophobicities. Some coatings promoted bacterial adhesion under centrifugation, whereas others were more likely to prevent it. Experiments were run using a simple buffer system and lysed blood, both inoculated with MSSA. Under both conditions, Hydromer's 7-TS-13 and Aqua65JL were most effective at reducing bacterial adhesion.

  5. Performance of the Tin-Free Antifouling Coating International Ecoloflex in DSTO/RAN Trials

    DTIC Science & Technology

    2008-10-01

    Defence Science and Technology Organisation 506 Lorimer St Fishermans Bend, Victoria 3207 Australia Telephone: (03) 9626 7000 Fax: (03) 9626 7999...at Williamstown in northern Port Phillip Bay, Victoria , and at the tropical site in Trinity Inlet, Cairns, Queensland. For each of these sites...Trial 1179) To assess the performance of tin-free products for harbour and support craft, strips of 5 coatings, including Ecoloflex, were applied to

  6. Zwitterions coated hollow fiber membranes with enhanced antifouling properties for osmotic power generation from municipal wastewater.

    PubMed

    Zhao, Dieling; Qiu, Guanglei; Li, Xue; Wan, Chunfeng; Lu, Kangjia; Chung, Tai-Shung

    2016-11-01

    Fouling on pressure-retarded osmosis (PRO) membranes leads to severe declines in water flux and power density because their porous substrates are facing the wastewater feed. Thus, inorganics, organics and microorganisms in the wastewater are prone to depositing on the substrate surface and even in its pores. In order to reduce the fouling propensity, coating the substrate surface of PRO membranes with zwitterionic materials proves to be an effective way. In this work, 2-methacryloyloxyethylphosphorylcholine (MPC), is modified and grafted onto the polydopamine (PDA) coated poly (ether sulfone) (PES) hollow fiber substrate. Both the synthesis and surface coating of MPC are easy and facile to be scaled up. Compared with the pristine PES and PES-PDA substrates, the MPC modified substrate (PES-PDA-MPC) exhibits high resistance to protein adsorption as well as bacteria adhesion. By using a state-of-the-art thin-film composite poly (ether sulfone) (TFC-PES) hollow fiber membrane as the control for power generation, the power density of the TFC-PES-PDA-MPC membrane can achieve as high as 7.7 W/m(2) while the unmodified one has only 6.0 W/m(2) after 3 h's PRO tests. In conclusion, the osmotic power generation of PRO membranes can be significantly sustained by modifying the membrane surface with zwitterions.

  7. Scanning Electron Microscope Observations of Marine Microorganisms on Surfaces Coated with Antifouling Paints.

    DTIC Science & Technology

    1981-06-01

    Vacuum Corporation , Cherry Hill, New Jersey. The size of the pedestal upon which the plating was done per- mitted only one slide to be coated at a time...Chemical Corporation , durez plastics division, 14120 Walck Road, North Tonawanda, New Jersey. 4. CAB-O-SIL M-5 is manufactured by Cabot Corpora- tion, 125...505 is an epoxy resin with a density of 1.01 g/cc. It is manufactured by the Celanese Corporation . 4. The organotin component of this formulation is

  8. Designing biomimetic antifouling surfaces.

    PubMed

    Salta, Maria; Wharton, Julian A; Stoodley, Paul; Dennington, Simon P; Goodes, Liam R; Werwinski, Stéphane; Mart, Ugar; Wood, Robert J K; Stokes, Keith R

    2010-10-28

    Marine biofouling is the accumulation of biological material on underwater surfaces, which has plagued both commercial and naval fleets. Biomimetic approaches may well provide new insights into designing and developing alternative, non-toxic, surface-active antifouling (AF) technologies. In the marine environment, all submerged surfaces are affected by the attachment of fouling organisms, such as bacteria, diatoms, algae and invertebrates, causing increased hydrodynamic drag, resulting in increased fuel consumption, and decreased speed and operational range. There are also additional expenses of dry-docking, together with increased fuel costs and corrosion, which are all important economic factors that demand the prevention of biofouling. Past solutions to AF have generally used toxic paints or coatings that have had a detrimental effect on marine life worldwide. The prohibited use of these antifoulants has led to the search for biologically inspired AF strategies. This review will explore the natural and biomimetic AF surface strategies for marine systems.

  9. Hybrid Antifouling and Antimicrobial Coatings Prepared by Electroless Co-Deposition of Fluoropolymer and Cationic Silica Nanoparticles on Stainless Steel: Efficacy against Listeria monocytogenes.

    PubMed

    Huang, Kang; Chen, Juhong; Nugen, Sam R; Goddard, Julie M

    2016-06-29

    Controlling formation, establishment, and proliferation of microbial biofilms on surfaces is critical for ensuring public safety. Herein, we report on the synthesis of antimicrobial nanoparticles and their co-deposition along with fluorinated nanoparticles during electroless nickel plating of stainless steel. Plating bath composition is optimized to ensure sufficiently low surface energy to resist fouling and microbial adhesion as well as to exert significant (>99.99% reduction) antimicrobial activity against Listeria monocytogenes. The resulting coatings present hybrid antifouling and antimicrobial character, can be applied onto stainless steel, and do not rely on leaching or migration of the antimicrobial nanoparticles to be effective. Such coatings can support reducing public health issues related to microbial cross-contamination in areas such as food processing, hospitals, and water purification.

  10. Advanced Polyelectrolyte-Modified Zinc Phosphate Coatings

    DTIC Science & Technology

    1995-09-01

    September 1995 4 . TITLE AND SUBTITLE Advanced Polyelectrolyte-Modified Zinc Phosphate Coatings 6. AUTHOR(S) T. Sugama, N. Carciello and C.I...ADVANCED POLYELECTROLYTE-MODIFIED ZINC PHOSPHATE COATINGS ft PAL - ?y- 3 $> Phase I. Annual Report (October 1994 - September 1995) ^ by T. Sugama, N...and Cr-nitrates, 3 ) the substitution of environmentally safe polyelectrolyte for the conventional chrome-based compounds in the rinsing process, 4

  11. Development of the primary bacterial microfouling layer on antifouling and fouling release coatings in temperate and tropical environments in Eastern Australia.

    PubMed

    Molino, Paul J; Childs, Samantha; Eason Hubbard, Maeve R; Carey, Janet M; Burgman, Mark A; Wetherbee, Richard

    2009-01-01

    The role played by bacteria during the pioneering stages of colonisation on marine coatings was investigated over three distinct seasons in both tropical and temperate environments. Novel methods were developed to facilitate the study of the adhered bacterial population on the test coatings in their native, hydrated state. The approach eliminated destructive sample preparation techniques, including sample dehydration and/or removal from the substratum surface prior to analysis. Bacterial colonisation during initial biofilm formation was evaluated on two antifouling paints, Intersmooth 360 and Super Yacht 800, and a fouling release coating, Intersleek 700. Bacterial colonisation was quantified on all three coating surfaces. Intersleek 700 displayed the quickest colonisation by bacteria, resulting in major modification of the substratum surface within 2-4 days following immersion in the ocean. Whilst fouling accumulated more quickly on Intersleek 700, by 16 days all three coatings were fouled significantly. Bacterial fouling was correlated to both location and season, with fouling occurring at a more rapid rate at the Cairns location, as well as during the summer months, when higher water temperatures were recorded. Successful colonisation of all coatings by bacteria soon after immersion modifies the characteristics of the surfaces at the hull/water interface, and subsequent settlement by higher biofouling organisms must be moderated by these modified surfaces.

  12. Colonisation and succession of marine biofilm-dwelling ciliate assemblages on biocidal antifouling and fouling-release coatings in temperate Australia.

    PubMed

    Watson, Matthew G; Scardino, Andrew J; Zalizniak, Liliana; Shimeta, Jeff

    2015-01-01

    Ciliate assemblages are often overlooked, but ubiquitous components of microbial biofilms which require a better understanding. Ciliate, diatom and bacterial colonisation were evaluated on two fouling-release (FR) coatings, viz. Intersleek 970 and Hempasil X3, and two biocidal antifouling (AF) coatings, viz. Intersmooth 360 and Interspeed 5640, in Port Phillip Bay, Australia. A total of 15 genera were identified during the 10 week deployment. Intersleek 970 displayed the most rapid fouling by ciliates, reaching 63.3(± 5.9) cells cm(-2). After 10 weeks, all four coatings were extensively fouled. However, the toxicity of the AF coatings still significantly inhibited microbial fouling compared to the FR coatings. On all treatments, colonies of sessile peritrichs dominated the ciliate assemblage in the early stage of succession, but as the biofilm matured, vagile ciliates exerted more influence on the assemblage structure. The AF coatings showed selective toxic effects, causing significant differences in the ciliate species assemblages among the treatments.

  13. Quantification of bacteria on abiotic surfaces by laser scanning cytometry: an automated approach to screen the antifouling properties of new surface coatings.

    PubMed

    Regina, Viduthalai Rasheedkhan; Poulsen, Morten; Søhoel, Helmer; Bischoff, Claus; Meyer, Rikke Louise

    2012-08-01

    Bacterial biofilms are a persistent source of contamination, and much effort has been invested in developing antifouling surfaces or coatings. A bottleneck in developing such coatings is often the time-consuming task of screening and evaluating a large number of surface materials. An automated high-throughput assay is therefore needed. In this study, we present a promising technique, laser scanning cytometry (LSC), for automated quantification of bacteria on surfaces. The method was evaluated by quantifying young Staphylococcus xylosus biofilms on glass surfaces using LSC and comparing the results with cell counts obtained by fluorescence microscopy. As an example of application, we quantified bacterial adhesion to seven different sol-gel-based coatings on stainless steel. The surface structure and hydrophobicity of the coatings were analyzed using atomic force microscopy and water contact angle measurements. Among the coatings tested, a significant reduction in adhesion of S. xylosus was observed only for one coating, which also had a unique surface microstructure. LSC was particularly sensitive for quantification at low cell densities, and the adhered bacteria could be quantified both as cell number and as area coverage. The method proved to be an excellent alternative to microscopy for fast and reproducible quantification of microbial colonization on abiotic surfaces.

  14. Advanced Fuels Campaign Cladding & Coatings Meeting Summary

    SciTech Connect

    Not Listed

    2013-03-01

    The Fuel Cycle Research and Development (FCRD) Advanced Fuels Campaign (AFC) organized a Cladding and Coatings operational meeting February 12-13, 2013, at Oak Ridge National Laboratory (ORNL). Representatives from the U.S. Department of Energy (DOE), national laboratories, industry, and universities attended the two-day meeting. The purpose of the meeting was to discuss advanced cladding and cladding coating research and development (R&D); review experimental testing capabilities for assessing accident tolerant fuels; and review industry/university plans and experience in light water reactor (LWR) cladding and coating R&D.

  15. Complex shaped ZnO nano- and microstructure based polymer composites: mechanically stable and environmentally friendly coatings for potential antifouling applications.

    PubMed

    Hölken, Iris; Hoppe, Mathias; Mishra, Yogendra K; Gorb, Stanislav N; Adelung, Rainer; Baum, Martina J

    2016-03-14

    Since the prohibition of tributyltin (TBT)-based antifouling paints in 2008, the development of environmentally compatible and commercially realizable alternatives is a crucial issue. Cost effective fabrication of antifouling paints with desired physical and biocompatible features is simultaneously required and recent developments in the direction of inorganic nanomaterials could play a major role. In the present work, a solvent free polymer/particle-composite coating based on two component polythiourethane (PTU) and tetrapodal shaped ZnO (t-ZnO) nano- and microstructures has been synthesized and studied with respect to mechanical, chemical and biocompatibility properties. Furthermore, antifouling tests have been carried out in artificial seawater tanks. Four different PTU/t-ZnO composites with various t-ZnO filling fractions (0 wt%, 1 wt%, 5 wt%, 10 wt%) were prepared and the corresponding tensile, hardness, and pull-off test results revealed that the composite filled with 5 wt% t-ZnO exhibits the strongest mechanical properties. Surface free energy (SFE) studies using contact angle measurements showed that the SFE value decreases with an increase in t-ZnO filler amounts. The influence of t-ZnO on the polymerization reaction was confirmed by Fourier transform infrared-spectroscopy measurements and thermogravimetric analysis. The immersion tests demonstrated that fouling behavior of the PTU/t-ZnO composite with a 1 wt% t-ZnO filler has been decreased in comparison to pure PTU. The composite with a 5 wt% t-ZnO filler showed almost no biofouling.

  16. Quantitative exploration of the contribution of settlement, growth, dispersal and grazing to the accumulation of natural marine biofilms on antifouling and fouling-release coatings.

    PubMed

    Van Mooy, Benjamin A S; Hmelo, Laura R; Fredricks, Helen F; Ossolinski, Justin E; Pedler, Byron E; Bogorff, Daniel J; Smith, Peter J S

    2014-02-01

    The accumulation of microbial biofilms on ships' hulls negatively affects ship performance and efficiency while also playing a role in the establishment of even more detrimental hard-fouling communities. However, there is little quantitative information on how the accumulation rate of microbial biofilms is impacted by the balance of the rates of cell settlement, in situ production (ie growth), dispersal to surrounding waters and mortality induced by grazers. These rates were quantified on test panels coated with copper-based antifouling (AF) or polymer-based fouling-release (FR) coatings by using phospholipids as molecular proxies for microbial biomass. The results confirmed the accepted modes of efficacy of these two types of coatings. In a more extensive set of experiments with only the FR coatings, it was found that seasonally averaged cellular production rates were 1.5 ± 0.5 times greater than settlement and the dispersal rates were 2.7 ± 0.8 greater than grazing. The results of this study quantitatively describe the dynamic balance of processes leading to the accumulation of microbial biofilm on coatings designed for ships' hulls.

  17. Quantitative exploration of the contribution of settlement, growth, dispersal and grazing to the accumulation of natural marine biofilms on antifouling and fouling-release coatings

    PubMed Central

    Van Mooy, Benjamin A. S.; Hmelo, Laura R.; Fredricks, Helen F.; Ossolinski, Justin E.; Pedler, Byron E.; Bogorff, Daniel J.; Smith, Peter J.S.

    2014-01-01

    The accumulation of microbial biofilms on ships' hulls negatively affects ships' performance and efficiency while also moderating the establishment of even more detrimental hard-fouling communities. However, there is little quantitative information on how the accumulation rate of microbial biofilms is impacted by the balance of the rates of cell settlement, in situ production (ie growth), dispersal to surrounding waters and mortality induced by grazers. These rates were quantified on test panels coated with copper-based antifouling or polymer-based fouling-release coatings by using phospholipids as molecular proxies for microbial biomass. The results confirmed the accepted modes of efficacy of these two types of coatings. In a more extensive set of experiments with only the fouling-release coatings, it was found that seasonally averaged cellular production rates were 1.5 ± 0.5 times greater than settlement and the dispersal rates were 2.7 ± 0.8 greater than grazing. The results of this study quantitatively describe the dynamic balance of processes leading to microbial biofilm accumulation on coatings designed for ships' hulls. PMID:24417212

  18. Synthesis of chitosan capped copper oxide nanoleaves using high intensity (30kHz) ultrasound sonication and their application in antifouling coatings.

    PubMed

    Abiraman, Tamilselvan; Ramanathan, Ethirajan; Kavitha, Ganapathy; Rengasamy, Ramasamy; Balasubramanian, Sengottuvelan

    2017-01-01

    The synthesis of chitosan capped copper oxide nanoleaves (CCCO NLs) was carried out under three different reaction conditions viz. 1) room temperature, 2) 70°C and 3) high intensity ultrasound (30kHz) sonication method and it has been found that the high intensity ultrasound (30kHz) sonication is the best method when compared to other two methods. The advantages of the present synthetic method are: i) easy one step process, ii) lesser reaction time, iii) good yield, iv) reproducible and v) calcination is not required. The resulting chitosan capped copper oxide nanoleaves were characterized by Diffuse Reflectance UV-Visible Spectroscopy (DRS), Fourier Transform Infra-Red Spectroscopy (FT-IR), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM) and Thermo gravimetric analysis (TGA). The CCCO NLs were blended with commercial paints such as polyurethane clear, polyurethane white and acrylic emulsion and applied on to three different surfaces (wood, mild steel and cement slab panels). The hydrophilicity of CCCONP coated panels was analyzed by water contact angle measurement and their antifouling behavior was investigated against three different green and marine algae viz. Arthrospira, Chlorella and Amphora. The antifouling efficiency of the CCCO NLs against the algae was found to be 78-92%.

  19. Smooth Compliant Antifoulant Coatings.

    DTIC Science & Technology

    1982-09-30

    chain. The elastomer approach uses a conventional elastomeric material, such as neoprene, as a basic vehicle. The biocide is then blended with it. The...acoustic properties can be achieved without the structural limitations of elastomeric materials normally classed as compliant. Therefore, compliance, as...conventio paint base, they leach out too quickly to be acceptable for ACSAS. However, chemical incorporation of the biocide within elastomers such as

  20. Antifouling marine concrete

    SciTech Connect

    Vind, H P; Mathews, C W

    1980-07-01

    Various toxic agents were evaluated as the their capability to prevent or inhibit the attachment of marine fouling organisms to concrete. Creosote and bis-(tri-n-butyltin) oxide (TBTO) were impregnated into porous aggregate which was used in making concrete. Cuprous oxide, triphenyltin hydroxide (TPTH), and 2-2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane (methoxychlor) were used as dry additives. Two proprietary formulations were applied as coatings on untreated concrete. Test specimens were exposed at Port Hueneme, CA, and Key Biscayne, FL. The efficacy of toxicants was determined by periodically weighing the adhering fouling organisms. Concrete prepared with an aggregate impregnated with a TBTO/creosote mixture has demonstrated the best antifouling performance of those specimens exposed for more than one year. The two proprietary coatings and the concrete containing methoxychlor, TPTH, and cuprous oxide as dry additives have exhibited good antifouling properties, but they have been exposed for a shorter time. The strength of concrete containing the toxicants was acceptable, and the toxicants did not increase the corrosion rate of reinforcing rods. Organotin compounds were essentially unchanged in concrete specimens exposed 6 1/2 years in seawater.

  1. Antifouling marine concrete

    SciTech Connect

    Vind, H P; Mathews, C W

    1980-07-01

    Various toxic agents were evaluated as to their capability to prevent or inhibit the attachment of marine fouling organisms to concrete for OTEC plants. Creosote and bis-(tri-n-butyltin) oxide (TBTO) were impregnated into porous aggregate which was used in making concrete. Cuprous oxide, triphenyltin hydroxide (TPTH), and 2-2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane (methoxychlor) were used as dry additives. Two proprietary formulations were applied as coatings on untreated concrete. Test specimens were exposed at Port Hueneme, CA, and Key Biscayne, FL. The efficacy of toxicants was determined by periodically weighing the adhering fouling organisms. Concrete prepared with an aggregate impregnated with a TBTO/creosote mixture has demonstrated the best antifouling performance of those specimens exposed for more than one year. The two proprietary coatings and the concrete containing methoxychlor, TPTH, and cuprous oxide as dry additives have exhibited good antifouling properties, but they have been exposed for a shorter time. The strength of concrete containing the toxicants was acceptable, and the toxicants did not increase the corrosion rate of reinforcing rods. Organotin compounds were essentially unchanged in concrete specimens exposed 6-1/2 years in seawater.

  2. Highly effective permeability and antifouling performances of polypropylene non-woven fabric membranes modified with graphene oxide by inkjet printing and immersion coating methods.

    PubMed

    Zhao, Chuan-Qi; Xu, Xiao-Chen; Li, Rui-Yun; Chen, Jie; Yang, Feng-Lin

    2013-01-01

    In the current study, graphene oxide (GO)-modified polypropylene non-woven fabric (PP-NWF) membranes were prepared via inkjet printing and immersion coating methods. Scanning electron microscopy, Fourier transform infrared spectroscopy, contact angle measurements, pure water permeation (JPWP) and protein adsorption were tested to evaluate the impact of the GO nanosheet on the characteristics and performance of modified PP-NWF membranes. The results showed that the exfoliated GO nanosheets uniformly deposited on the membrane surface and firmly embedded into the interlaced fibers, resulting in the improvement of membrane hydrophilicity, permeability and antifouling properties comparing with original PP-NWF membranes. The GO-printed and GO-coated membranes had 113 and 188% higher fluxes, and 70.95 and 75.74% lower protein adsorptions than the original PP-NWF membranes, respectively. After cross-linked treatment, ultrasound processing was conducted to evaluate the stability of the modified PP-NWF membranes. The results demonstrated that there was almost no decrease in permeation after ultrasonic treatment indicating that the cross-linking treatment could enhance the immobilization of the GO nanosheets on and into the modified membranes.

  3. Evaluation of Erosion Resistance of Advanced Turbine Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Kuczmarski, Maria A.; Miller, Robert A.; Cuy, Michael D.

    2007-01-01

    The erosion resistant turbine thermal barrier coating system is critical to aircraft engine performance and durability. By demonstrating advanced turbine material testing capabilities, we will be able to facilitate the critical turbine coating and subcomponent development and help establish advanced erosion-resistant turbine airfoil thermal barrier coatings design tools. The objective of this work is to determine erosion resistance of advanced thermal barrier coating systems under simulated engine erosion and/or thermal gradient environments, validating advanced turbine airfoil thermal barrier coating systems based on nano-tetragonal phase toughening design approaches.

  4. Progress to Develop an Advanced Solar-Selective Coating

    SciTech Connect

    Kennedy, C. E.

    2008-03-01

    The progress to develop a durable advanced solar-selective coating will be described. Experimental work has focused on modeling high-temperature, solar-selective coatings; depositing the individual layers and modeled coatings; measuring the optical, thermal, morphology, and compositional properties and using the data to validate the modeled and deposited properties; re-optimizing the coating; and testing the coating performance and durability.

  5. Thermal Conductivity and Sintering Behavior of Advanced Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    2002-01-01

    Advanced thermal barrier coatings, having significantly reduced long-term thermal conductivities, are being developed using an approach that emphasizes real-time monitoring of thermal conductivity under conditions that are engine-like in terms of temperatures and heat fluxes. This is in contrast to the traditional approach where coatings are initially optimized in terms of furnace and burner rig durability with subsequent measurement in the as-processed or furnace-sintered condition. The present work establishes a laser high-heat-flux test as the basis for evaluating advanced plasma-sprayed and physical vapor-deposited thermal barrier coatings under the NASA Ultra Efficient Engine Technology (UEET) Program. The candidate coating materials for this program are novel thermal barrier coatings that are found to have significantly reduced thermal conductivities due to an oxide-defect-cluster design. Critical issues for designing advanced low conductivity coatings with improved coating durability are also discussed.

  6. Thermal Barrier Coatings for Advanced Gas Turbine and Diesel Engines

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    1999-01-01

    Ceramic thermal barrier coatings (TBCS) have been developed for advanced gas turbine and diesel engine applications to improve engine reliability and fuel efficiency. However, durability issues of these thermal barrier coatings under high temperature cyclic conditions are still of major concern. The coating failure depends not only on the coating, but also on the ceramic sintering/creep and bond coat oxidation under the operating conditions. Novel test approaches have been established to obtain critical thermomechanical and thermophysical properties of the coating systems under near-realistic transient and steady state temperature and stress gradients encountered in advanced engine systems. This paper presents detailed experimental and modeling results describing processes occurring in the ZrO2-Y2O3 thermal barrier coating systems, thus providing a framework for developing strategies to manage ceramic coating architecture, microstructure and properties.

  7. Superhydrophobicity for antifouling microfluidic surfaces.

    PubMed

    Shirtcliffe, N J; Roach, P

    2013-01-01

    Fouling of surfaces is often problematic in microfluidic devices, particularly when using protein or -enzymatic solutions. Various coating methods have been investigated to reduce the tendency for protein molecules to adsorb, mostly relying on hydrophobic surface chemistry or the antifouling ability of -polyethylene glycol. Here we present the potential use of superhydrophobic surfaces to not only reduce the amount of surface contamination but also to induce self-cleaning under flow conditions. The methodology is presented in order to prepare superhydrophobic surface coatings having micro- and nanoscale feature dimensions, as well as a step-by-step guide to quantify adsorbed protein down to nanogram levels. The fabrication of these surfaces as coatings via silica sol-gel and copper nano-hair growth is presented, which can be applied within microfluidic devices manufactured from various materials.

  8. Antifouling leaching technique for optical lenses

    USGS Publications Warehouse

    Strahle, William J.; Perez, C. L.; Martini, Marinna A.

    1994-01-01

    The effectiveness of optical lenses deployed in water less than 100 m deep is significantly reduced by biofouling caused by the settlement of macrofauna, such as barnacles, hydroids, and tunicates. However, machineable porous plastic rings can be used to dispense antifoulant into the water in front of the lens to retard macrofaunal growth without obstructing the light path. Unlike coatings which can degrade the optical performance, antifouling rings do not interfere with the instrument optics. The authors have designed plastic, reusable cup-like antifouling rings to slip over the optical lenses of a transmissometer. These rings have been used for several deployments on shallow moorings in Massachusetts Bay, MA and have increased the time before fouling degrades optical characteristics

  9. Thermal and Environmental Barrier Coatings for Advanced Propulsion Engine Systems

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming; Miller, Robert A.

    2004-01-01

    Ceramic thermal and environmental barrier coatings (TEBCs) are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments, and extend component lifetimes. For future high performance engines, the development of advanced ceramic barrier coating systems will allow these coatings to be used to simultaneously increase engine operating temperature and reduce cooling requirements, thereby leading to significant improvements in engine power density and efficiency. In order to meet future engine performance and reliability requirements, the coating systems must be designed with increased high temperature stability, lower thermal conductivity, and improved thermal stress and erosion resistance. In this paper, ceramic coating design and testing considerations will be described for high temperature and high-heat-flux engine applications in hot corrosion and oxidation, erosion, and combustion water vapor environments. Further coating performance and life improvements will be expected by utilizing advanced coating architecture design, composition optimization, and improved processing techniques, in conjunction with modeling and design tools.

  10. Mickey Leland Energy Fellowship Report: Development of Advanced Window Coatings

    SciTech Connect

    Bolton, Ladena A.; Alvine, Kyle J.; Schemer-Kohrn, Alan L.

    2014-08-05

    Advanced fenestration technologies for light and thermal management in building applications are of great recent research interest for improvements in energy efficiency. Of these technologies, there is specific interest in advanced window coating technologies that have tailored control over the visible and infrared (IR) scattering into a room for both static and dynamic applications. Recently, PNNL has investigated novel subwavelength nanostructured coatings for both daylighting, and IR thermal management applications. Such coatings rese still in the early stages and additional research is needed in terms of scalable manufacturing. This project investigates aspects of a potential new methodology for low-cost scalable manufacture of said subwavelength coatings.

  11. Challenges for the Development of New Non-Toxic Antifouling Solutions

    PubMed Central

    Maréchal, Jean-Philippe; Hellio, Claire

    2009-01-01

    Marine biofouling is of major economic concern to all marine industries. The shipping trade is particularly alert to the development of new antifouling (AF) strategies, especially green AF paint as international regulations regarding the environmental impact of the compounds actually incorporated into the formulations are becoming more and more strict. It is also recognised that vessels play an extensive role in invasive species propagation as ballast waters transport potentially threatening larvae. It is then crucial to develop new AF solutions combining advances in marine chemistry and topography, in addition to a knowledge of marine biofoulers, with respect to the marine environment. This review presents the recent research progress made in the field of new non-toxic AF solutions (new microtexturing of surfaces, foul-release coatings, and with a special emphasis on marine natural antifoulants) as well as the perspectives for future research directions. PMID:20087457

  12. Advanced ceramic coating development for industrial/utility gas turbines

    NASA Technical Reports Server (NTRS)

    Vogan, J. W.; Stetson, A. R.

    1982-01-01

    A program was conducted with the objective of developing advanced thermal barrier coating (TBC) systems. Coating application was by plasma spray. Duplex, triplex and graded coatings were tested. Coating systems incorporated both NiCrAly and CoCrAly bond coats. Four ceramic overlays were tested: ZrO2.82O3; CaO.TiO2; 2CaO.SiO2; and MgO.Al2O3. The best overall results were obtained with a CaO.TiO2 coating applied to a NiCrAly bond coat. This coating was less sensitive than the ZrO2.8Y2O3 coating to process variables and part geometry. Testing with fuels contaminated with compounds containing sulfur, phosphorus and alkali metals showed the zirconia coatings were destabilized. The calcium titanate coatings were not affected by these contaminants. However, when fuels were used containing 50 ppm of vanadium and 150 ppm of magnesium, heavy deposits were formed on the test specimens and combustor components that required frequent cleaning of the test rig. During the program Mars engine first-stage turbine blades were coated and installed for an engine cyclic endurance run with the zirconia, calcium titanate, and calcium silicate coatings. Heavy spalling developed with the calcium silicate system. The zirconia and calcium titanate systems survived the full test duration. It was concluded that these two TBC's showed potential for application in gas turbines.

  13. Antifouling properties of hydrogels

    NASA Astrophysics Data System (ADS)

    Murosaki, Takayuki; Ahmed, Nafees; Gong, Jian Ping

    2011-12-01

    Marine sessile organisms easily adhere to submerged solids such as rocks, metals and plastics, but not to seaweeds and fishes, which are covered with soft and wet 'hydrogel'. Inspired by this fact, we have studied long-term antifouling properties of hydrogels against marine sessile organisms. Hydrogels, especially those containing hydroxy group and sulfonic group, show excellent antifouling activity against barnacles both in laboratory assays and in the marine environment. The extreme low settlement on hydrogels in vitro and in vivo is mainly caused by antifouling properties against the barnacle cypris.

  14. Antifouling properties of hydrogels

    PubMed Central

    Murosaki, Takayuki; Ahmed, Nafees; Ping Gong, Jian

    2011-01-01

    Marine sessile organisms easily adhere to submerged solids such as rocks, metals and plastics, but not to seaweeds and fishes, which are covered with soft and wet ‘hydrogel’. Inspired by this fact, we have studied long-term antifouling properties of hydrogels against marine sessile organisms. Hydrogels, especially those containing hydroxy group and sulfonic group, show excellent antifouling activity against barnacles both in laboratory assays and in the marine environment. The extreme low settlement on hydrogels in vitro and in vivo is mainly caused by antifouling properties against the barnacle cypris. PMID:27877456

  15. Advanced optical coatings for astronomical instrumentation

    NASA Astrophysics Data System (ADS)

    Pradal, Fabien; Leplan, Hervé; Vayssade, Hervé; Geyl, Roland

    2016-07-01

    Recently Safran Reosc worked and progressed on various thin film technology for: Large mirrors with low stress and stable coatings. Large lens elements with strong curvature and precise layer specifications. Large filters with high spectral response uniformity specifications. IR coatings with low stress and excellent resistance to cryogenic environment for NIR to LWIR domains. Pixelated coatings. Results will be presented and discussed on the basis of several examples.

  16. Minimally Adhesive, Advanced Non-toxic Coatings of Dendrimeric Catalysts in Sol-Gel Matrices

    DTIC Science & Technology

    2015-10-19

    Catalysts in Sol-Gel Matrices 5a. CONTRACT NUMBER 5b. GRANT NUMBER N00014-09-1-0217 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Detty, Michael R. 5d...SUPPLEMENTARY NOTES 14. ABSTRACT We have developed new xerogel coatings with organochalcogenide or metal oxide catalysts for the activation of...hydrogen peroxide as anti-fouling, fouling-release surfaces. The catalysts perform more efficiently when covalently attached to the xerogel framework

  17. Development of high viscosity coatings for advanced Space Shuttle applications

    NASA Technical Reports Server (NTRS)

    Garofalini, S. H.; Banas, R.; Creedon, J.

    1979-01-01

    Laboratory studies for increasing the thermal resistance of high viscosity coatings for silica reusable surface insulation are presented. The coatings are intended for the reentry temperature associated with advanced Space Shuttle applications which will involve aerodynamic shear forces during entry from earth orbits. Coating viscosity was increased by (1) reduction in the concentration of the low viscosity additive B2O3; (2) reduction in the particle size of the constituent powders in coatings; and (3) addition of a high viscosity glass former (GeO2). A coating system was produced by combining the three methods which showed apparent higher viscosity than the current coating, while satisfying all the current Shuttle Orbiter coating requirements.

  18. Advanced Low Conductivity Thermal Barrier Coatings: Performance and Future Directions

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    2008-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and performance will be emphasized. Advanced thermal barrier coatings have been developed using a multi-component defect clustering approach, and shown to have improved thermal stability and lower conductivity. The coating systems have been demonstrated for high temperature combustor applications. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the toughened thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion, impact and high heat-flux damage mechanisms of the thermal barrier coatings will also be described.

  19. Development of Advanced Low Conductivity Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming; Miller, Robert A.

    2004-01-01

    Advanced multi-component, low conductivity oxide thermal barrier coatings have been developed using an approach that emphasizes real-time monitoring of thermal conductivity under conditions that are engine-like in terms of temperatures and heat fluxes. This is in contrast to the traditional approach where coatings are initially optimized in terms of furnace and burner rig durability with subsequent measurement in the as-processed or furnace-sintered condition. The present work establishes a laser high-heat-flux test as the basis for evaluating advanced plasma-sprayed and electron beam-physical vapor deposited (EB-PVD) thermal barrier coatings under the NASA Ultra-Efficient Engine Technology (UEET) Program. The candidate coating materials for this program are novel thermal barrier coatings that are found to have significantly reduced thermal conductivities and improved thermal stability due to an oxide-defect-cluster design. Critical issues for designing advanced low conductivity coatings with improved coating durability are also discussed.

  20. Advanced Environmental Barrier Coatings Development for Si-Based Ceramics

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming; Choi, R. Sung; Robinson, Raymond C.; Lee, Kang N.; Bhatt, Ramakrishna T.; Miller, Robert A.

    2005-01-01

    Advanced environmental barrier coating concepts based on multi-component HfO2 (ZrO2) and modified mullite systems are developed for monolithic Si3N4 and SiC/SiC ceramic matrix composite (CMC) applications. Comprehensive testing approaches were established using the water vapor cyclic furnace, high pressure burner rig and laser heat flux steam rig to evaluate the coating water vapor stability, cyclic durability, radiation and erosion resistance under simulated engine environments. Test results demonstrated the feasibility and durability of the environmental barrier coating systems for 2700 to 3000 F monolithic Si3N4 and SiC/SiC CMC component applications. The high-temperature-capable environmental barrier coating systems are being further developed and optimized in collaboration with engine companies for advanced turbine engine applications.

  1. Progress in advanced high temperature turbine materials, coatings, and technology

    NASA Technical Reports Server (NTRS)

    Freche, J. C.; Ault, G. M.

    1978-01-01

    Advanced materials, coatings, and cooling technology is assessed in terms of improved aircraft turbine engine performance. High cycle operating temperatures, lighter structural components, and adequate resistance to the various environmental factors associated with aircraft gas turbine engines are among the factors considered. Emphasis is placed on progress in development of high temperature materials for coating protection against oxidation, hot corrosion and erosion, and in turbine cooling technology. Specific topics discussed include metal matrix composites, superalloys, directionally solidified eutectics, and ceramics.

  2. Therma1 Conductivity and Durability of Advanced Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming; Miller, Robert A.

    2003-01-01

    Thermal barrier coatings (TBCs) will play a crucial role in advanced gas turbine engines because of their ability to further increase engine operating temperature and reduce cooling, thus helping to achieve engine emission and efficiency goals. Future TBCs must be designed with increased phase stability, lower thermal conductivity, and improved sintering and thermal stress resistance in order to effectively protect engine hot-section components. Advanced low conductivity TBCs are being developed at NASA by incorporating multi-component oxide dopants into zirconia-yttria or hafnia-yttria to promote the formation of thermodynamically stable defect clusters within the coating structures. This presentation will primarily focus on thermal conductivity and durability of the novel defect cluster thermal barrier coatings for turbine airfoil and combustor applications, determined by a unique CO2 laser heat-flux approach. The laser heat-flux testing approach emphasizes the real-time monitoring and assessment of the coating thermal conductivity under simulated engine temperature and thermal gradient conditions. The conductivity increase due to coating sintering (and/or phase change) and the conductivity decrease due to coating delamination have been determined under steady-state, cyclic, uniform or non-uniform heat-flux conditions. The coating radiation flux resistance has been evaluated by varying coating thermal gradients, and also by using a laser-heated radiative-flux source. Advanced multi-component TBC systems have been shown to have significantly reduced thermal conductivity and improved high temperature stability due to the nano-sized, low mobility defect clusters associated with the paired rare earth dopant additions. The effect of oxide defect cluster dopants on coating thermal conductivity, thermal stability and furnace cyclic durability will also be discussed. The current low conductivity TBC systems have demonstrated long-term cyclic durability at very high

  3. Application of advanced coating techniques to rocket engine components

    NASA Technical Reports Server (NTRS)

    Verma, S. K.

    1988-01-01

    The materials problem in the space shuttle main engine (SSME) is reviewed. Potential coatings and the method of their application for improved life of SSME components are discussed. A number of advanced coatings for turbine blade components and disks are being developed and tested in a multispecimen thermal fatigue fluidized bed facility at IIT Research Institute. This facility is capable of producing severe strains of the degree present in blades and disk components of the SSME. The potential coating systems and current efforts at IITRI being taken for life extension of the SSME components are summarized.

  4. Development of improved coating for advanced carbon-carbon components

    NASA Technical Reports Server (NTRS)

    Yamaki, Y. R.; Brown, J. J.

    1984-01-01

    Reaction sintered silicon nitride (RSSN) was studied as a substitute coating material on the carbon-carbon material (RCC) presently used as a heat shield on the space shuttle, and on advanced carbon-carbon (ACC), a later development. On RCC, RSSN showed potential in a 538 C (1000 F) screening test in which silicon carbide coated material exhibits its highest oxidation rate; RSSN afforded less protection to ACC because of a larger thermal expansion mismatch. Organosilicon densification and metallic silicon sealing methods were studied as means of further increasing the oxidation resistance of the coating, and some improvement was noted when these methods were employed.

  5. Silica suspension and coating developments for Advanced LIGO

    NASA Astrophysics Data System (ADS)

    Cagnoli, G.; Armandula, H.; Cantley, C. A.; Crooks, D. R. M.; Cumming, A.; Elliffe, E.; Fejer, M. M.; Gretarsson, A. M.; Harry, G. M.; Heptonstall, A.; Hough, J.; Jones, R.; Mackowski, J.-M.; Martin, I.; Murray, P.; Penn, S. D.; Perreur-Lloyd, M.; Reid, S.; Route, R.; Rowan, S.; Robertson, N. A. A.; Sneddon, P. H.; Strain, K. A.

    2006-03-01

    The proposed upgrade to the LIGO detectors to form the Advanced LIGO detector system is intended to incorporate a low thermal noise monolithic fused silica final stage test mass suspension based on developments of the GEO 600 suspension design. This will include fused silica suspension elements jointed to fused silica test mass substrates, to which dielectric mirror coatings are applied. The silica fibres used for GEO 600 were pulled using a Hydrogen-Oxygen flame system. This successful system has some limitations, however, that needed to be overcome for the more demanding suspensions required for Advanced LIGO. To this end a fibre pulling machine based on a CO2 laser as the heating element is being developed in Glasgow with funding from EGO and PPARC. At the moment a significant limitation for proposed detectors like Advanced LIGO is expected to come from the thermal noise of the mirror coatings. An investigation on mechanical losses of silica/tantala coatings was carried out by several labs involved with Advanced LIGO R&D. Doping the tantala coating layer with titania was found to reduce the coating mechanical dissipation. A review of the results is given here.

  6. Advances in the electrospark deposition coating process

    SciTech Connect

    Johnson, R.N.; Sheldon, G.L.

    1986-11-01

    Electrospark deposition (ESD) is a pulsed-arc microwelding process using short-duration, high-current electrical pulses to deposit an electrode material on a metallic substrate. It is one of the few methods available by which a fused, metallurgically bonded coating can be applied with such a low total heat input that the bulk substrate material remains at or near ambient temperatures. The short duration of the electrical pulse allows an extremely rapid solidification of the deposited material and results in an exceptionally fine-grained, homogeneous coating that approaches (and with some materials, actually is) an amorphous structure. This structure is believed to contribute to the good tribological and corrosion performance observed for hardsurfacing materials used in the demanding environments of high temperatures, liquid metals, and neutron irradiation. A brief historical review of the process is provided, followed by descriptions of the present state of the art and of the performance and applications of electrospark deposition coating in liquid--metal-cooled nuclear reactors.

  7. Advanced Materials and Coatings for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2004-01-01

    In the application area of aerospace tribology, researchers and developers must guarantee the highest degree of reliability for materials, components, and systems. Even a small tribological failure can lead to catastrophic results. The absence of the required knowledge of tribology, as Professor H.P. Jost has said, can act as a severe brake in aerospace vehicle systems-and indeed has already done so. Materials and coatings must be able to withstand the aerospace environments that they encounter, such as vacuum terrestrial, ascent, and descent environments; be resistant to the degrading effects of air, water vapor, sand, foreign substances, and radiation during a lengthy service; be able to withstand the loads, stresses, and temperatures encountered form acceleration and vibration during operation; and be able to support reliable tribological operations in harsh environments throughout the mission of the vehicle. This presentation id divided into two sections: surface properties and technology practice related to aerospace tribology. The first section is concerned with the fundamental properties of the surfaces of solid-film lubricants and related materials and coatings, including carbon nanotubes. The second is devoted to applications. Case studies are used to review some aspects of real problems related to aerospace systems to help engineers and scientists to understand the tribological issues and failures. The nature of each problem is analyzed, and the tribological properties are examined. All the fundamental studies and case studies were conducted at the NASA Glenn Research Center.

  8. Case history advanced coatings for water treatment plant components

    SciTech Connect

    Stephenson, L.D.; Kumar, A.

    2008-12-15

    Components of water treatment plants (WTPs) are susceptible to corrosion from constant immersion in water. A case history of corrosion and proximity to chlorine problems and their treatment at an Army WTP is presented. Solutions included using high micro-silica restoration mortar and advanced coal tar epoxy coatings.

  9. ADVANCED HOT SECTION MATERIALS AND COATINGS TEST RIG

    SciTech Connect

    Scott Reome; Dan Davies

    2004-04-30

    The Hyperbaric Advanced Hot Section Materials & Coating Test Rig program provides design and implementation of a laboratory rig capable of simulating the hot gas path conditions of coal-gas fired industrial gas turbine engines. The principal activity during this reporting period were the evaluation of syngas combustor concepts, the evaluation of test section concepts and the selection of the preferred rig configuration.

  10. Membranes with Surface-Enhanced Antifouling Properties for Water Purification

    PubMed Central

    Shahkaramipour, Nima; Tran, Thien N.; Ramanan, Sankara; Lin, Haiqing

    2017-01-01

    Membrane technology has emerged as an attractive approach for water purification, while mitigation of fouling is key to lower membrane operating costs. This article reviews various materials with antifouling properties that can be coated or grafted onto the membrane surface to improve the antifouling properties of the membranes and thus, retain high water permeance. These materials can be separated into three categories, hydrophilic materials, such as poly(ethylene glycol), polydopamine and zwitterions, hydrophobic materials, such as fluoropolymers, and amphiphilic materials. The states of water in these materials and the mechanisms for the antifouling properties are discussed. The corresponding approaches to coat or graft these materials on the membrane surface are reviewed, and the materials with promising performance are highlighted. PMID:28273869

  11. Thermal and Environmental Barrier Coatings for Advanced Turbine Engine Applications

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming; Miller, Robert A.

    2005-01-01

    Ceramic thermal and environmental barrier coatings (T/EBCs) will play a crucial role in advanced gas turbine engine systems because of their ability to significantly increase engine operating temperatures and reduce cooling requirements, thus help achieve engine low emission and high efficiency goals. Advanced T/EBCs are being developed for the low emission SiC/SiC ceramic matrix composite (CMC) combustor applications by extending the CMC liner and vane temperature capability to 1650 C (3000 F) in oxidizing and water vapor containing combustion environments. Low conductivity thermal barrier coatings (TBCs) are also being developed for metallic turbine airfoil and combustor applications, providing the component temperature capability up to 1650 C (3000 F). In this paper, ceramic coating development considerations and requirements for both the ceramic and metallic components will be described for engine high temperature and high-heat-flux applications. The underlying coating failure mechanisms and life prediction approaches will be discussed based on the simulated engine tests and fracture mechanics modeling results.

  12. Coating parameters of zirconium carbide on advanced TRISO fuels

    NASA Astrophysics Data System (ADS)

    Dulude, Michael C.

    The feasibility of using very high temperature reactors (VHTR) as part of the next generation of nuclear reactors greatly depends on the tri-structural isotropic (TRISO) fuel particles reliability to retain both gaseous and metallic fission products created in irradiated UO2. Most research devoted to TRISO fuel particles has focused on the characteristics and retention ability of silicon carbide as the main barrier against metallic fission products. This work investigates the deposition parameters necessary to create advanced TRISO particles consisting of the standard SiC TRISO coatings with an additional layer of ZrC applied directly to the UO2 fuel kernel. The additional ZrC layer will act as an oxygen getter to prevent failure mechanisms experienced in TRISO particles. Two failure mechanisms that are of the most concern are the over pressurization of the particles and kernel migration within the TRISO particles. In this study successful ZrC coatings were created and the deposition characteristics were analyzed via optical and SEM microscopy techniques. The ZrC layer was confirmed through XRD analysis. This investigation also reduced U3O8 microspheres to UO2 in an argon atmosphere. The oxygen to metal ratio from the reduced U3O8 was back calculated from oxidation analysis performed with a TGA machine. Once consistent repeatability is shown with coating surrogate zirconia kernels, advanced TRISO coatings will be deposited on the UO2 fuel kernels.

  13. Advanced Tribological Coatings for High Specific Strength Alloys

    DTIC Science & Technology

    1989-09-29

    Hard Anodised 4 HSSA12 (SHT) Plasma Nitrided 1 HSSA13 (H&G) Plasma Nitrided 2 HSSA14 (SHT) High Temperature Nitrocarburized 1 HSSA15 (H&G) Nitrox 1...HSSA26 ( High Temperature Plasma Nitriding) has recently arrived, and is currently undergoing metallographic examination. The remaining samples are still...Report No 3789/607 Advanced Tribological Coatings For High Specific Strength Alloys, R&D 5876-MS-01 Contract DAJ A45-87-C-0044 5th Interim Report

  14. In-Situ Investigation of Advanced Structural Coatings and Composites

    NASA Technical Reports Server (NTRS)

    Ustundag, Ersan

    2003-01-01

    The premise of this project is a comprehensive study that involves the in-situ characterization of advanced coatings and composites by employing both neutron and x-ray diffraction techniques in a complementary manner. The diffraction data would then be interpreted and used in developing or validating advanced micromechanics models with life prediction capability. In the period covered by this report, basic work was conducted to establish the experimental conditions for various specimens and techniques. In addition, equipment was developed that will allow the in-situ studies under a range of conditions (stress, temperature, atmosphere, etc.).

  15. Spin-Casting Polymer Brush Films for Stimuli-Responsive and Anti-Fouling Surfaces.

    PubMed

    Xu, Binbin; Feng, Chun; Hu, Jianhua; Shi, Ping; Gu, Guangxin; Wang, Lei; Huang, Xiaoyu

    2016-03-01

    Surfaces modified with amphiphilic polymers can dynamically alter their physicochemical properties in response to changes of their environmental conditions; meanwhile, amphiphilic polymer coatings with molecular hydrophilic and hydrophobic patches, which can mitigate biofouling effectively, are being actively explored as advanced coatings for antifouling materials. Herein, a series of well-defined amphiphilic asymmetric polymer brushes containing hetero side chains, hydrophobic polystyrene (PS) and hydrophilic poly(ethylene glycol) (PEG), was employed to prepare uniform thin films by spin-casting. The properties of these films were investigated by water contact angle, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and quartz crystal microbalance (QCM). AFM showed smooth surfaces for all films with the roughness less than 2 nm. The changes in water contact angle and C/O ratio (XPS) evidenced the enrichment of PEG or PS chains at film surface after exposed to selective solvents, indicative of stimuli- responsiveness. The adsorption of proteins on PEG functionalized surface was quantified by QCM and the results verified that amphiphilic polymer brush films bearing PEG chains could lower or eliminate protein-material interactions and resist to protein adsorption. Cell adhesion experiments were performed by using HaCaT cells and it was found that polymer brush films possess good antifouling ability.

  16. Advanced stent coating for drug delivery and in vivo biocompatibility

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Wang, Wuchen; Acharya, Gayathri; Shim, Yoon-Bo; Choe, Eun Sang; Lee, Chi H.

    2013-10-01

    As an effort to alleviate stent-induced cardiovascular injury including restenosis and thrombosis, advanced drug-eluting stent (ADES) with a bilayer construct composed of a top-coat made of collagen and a base-coat incorporated with N-nitrosomelatonin (NOMela)-loaded PLGA nanoparticles has been developed. NOMela is a hydrophobic prodrug of nitric oxide (NO) that is an endogenous anti-platelet compound. ADES was coated with PLGA nanoparticles via either electrophoretic deposition (EPD) technique or dip-coating technique, and their coating characteristics and efficacies were compared. The drug-loading efficacy and in vitro drug-release profiles from ADES were expressed with various variables including the additives to the collagen layer, the number of layers of the collagen top-coat, the hydrophobicity/hydrophilicity of the loaded drug, the coating technique of nanoparticles, and the concentration of coating emulsions in the EPD method. The morphological status of cross-section and surface of ADES was evaluated by laser scanning confocal microscope and scanning electronic microscope. The real-time release profiles of NO were assessed using the NO-microbiosensor. The anti-platelet activity of ADES was evaluated on the rabbit whole blood using an aggregometer. The intima formation and protein expression in aorta were examined using an in vivo rat model. Both collagen and PLGA used in ADES are biodegradable polymers that fully degrade and consequently produce less inflammation responses. NO released from ADES significantly reduced platelet aggregation in the rabbit blood as compared with those exposed to the control stents. ADES coated with a double layer consisted of collagen and PLGA and containing NOMela was less antigenic at the implanted sites and alleviating intima formation and thrombosis. An external exposure of aorta to NO elicits distinct and specific effects on mitogen-activated protein kinase (MAPK) and Ca2+/calmodulin-dependent protein kinase II (Ca

  17. Thin coatings for heavy industry: Advanced coatings for pipes and valves

    NASA Astrophysics Data System (ADS)

    Vernhes, Luc

    Pipes and valves are pressure vessels that regulate the flow of materials (liquids, gases, and slurries) by controlling the passageways. To optimize processes, reduce costs, and comply with government regulations, original equipment manufacturers (OEMs) must maintain their products in state-of-the-art condition. The first valves were invented over 3,000 years ago to supply water to farms and cities. They were made with bronze alloys, providing good corrosion resistance and acceptable tribological performance. The industrial revolution drove manufacturers to develop new and improved tribological materials. In the 20th century, innovative alloys such as Monel copper-nickel and Stellite cobalt-chrome as well as hard chrome plating were introduced to better control tribological properties and maximize in-service life. Since then, new materials have been regularly introduced to extend the range of applications for valves. For example, Teflon fluoropolymers are used in corrosive chemical and petrochemical processes, the nickel-based superalloys Hastelloy and Inconel for petrochemical applications, and creep-resistant chromium-rich F91 steel for supercritical power plants. Recently, the valve industry has embraced the use of hard thermal sprayed coatings for the most demanding applications, and is investing heavily in research to develop the most suitable coatings for specific uses. There is increasing evidence that the optimal solution to erosive, corrosive, and fretting wear problems lies in the design and manufacture of multi-layer, graded, and/or nanostructured coatings and coating systems that combine controlled hardness with high elastic modulus, high toughness, and good adhesion. The overall objectives of this thesis were 1) to report on advances in the development of structurally controlled hard protective coatings with tailored mechanical, elastoplastic, and thermal properties; and 2) to describe enhanced wear-, erosion-, and corrosion-resistance and other

  18. Advanced Hot Section Materials and Coatings Test Rig

    SciTech Connect

    Dan Davis

    2006-09-30

    Phase I of the Hyperbaric Advanced Hot Section Materials & Coating Test Rig Program has been successfully completed. Florida Turbine Technologies has designed and planned the implementation of a laboratory rig capable of simulating the hot gas path conditions of coal gas fired industrial gas turbine engines. Potential uses of this rig include investigations into environmental attack of turbine materials and coatings exposed to syngas, erosion, and thermal-mechanical fatigue. The principle activities during Phase 1 of this project included providing several conceptual designs for the test section, evaluating various syngas-fueled rig combustor concepts, comparing the various test section concepts and then selecting a configuration for detail design. Conceptual definition and requirements of auxiliary systems and facilities were also prepared. Implementation planning also progressed, with schedules prepared and future project milestones defined. The results of these tasks continue to show rig feasibility, both technically and economically.

  19. PEG-b-AGE Polymer Coated Magnetic Nanoparticle Probes with Facile Functionalization and Anti-fouling Properties for Reducing Non-specific Uptake and Improving Biomarker Targeting

    PubMed Central

    Wang, Liya; Huang, Jing; Wu, Hui; Cheng, Guojun; Zhou, Zhengyang; MacDonald, Tobey; Yang, Lily; Mao, Hui

    2015-01-01

    Non-specific surface adsorption of bio-macromolecules (e.g. proteins) on nanoparticles, known as biofouling, and the uptake of nanoparticles by the mononuclear phagocyte system (MPS) and reticuloendothelial system (RES) lead to substantial reduction in the efficiency of target-directed imaging and delivery in biomedical applications of engineered nanomaterials in vitro and in vivo. In this work, a novel copolymer consisting of blocks of poly ethylene glycol and allyl glycidyl ether (PEG-b-AGE) was developed for coating magnetic iron oxide nanoparticles (IONPs) to reduce non-specific protein adhesion that leads to formation of “protein corona” and uptake by macrophages. The facile surface functionalization was demonstrated by using targeting ligands of a small peptide of RGD or a whole protein of transferrin (Tf). The PEG-b-AGE coated IONPs exhibited anti-biofouling properties with significantly reduced protein corona formation and non-specific uptake by macrophages before and after the surface functionalization, thus improving targeting of RGD-conjugated PEG-b-AGE coated IONPs to integrins in U87MG glioblastoma and MDA-MB-231 breast cancer cells that overexpress αvβ3 integrins, and Tf-conjugated PEG-b-AGE coated IONPs to transferrin receptor (TfR) in D556 and Daoy medulloblastoma cancer cells with high overexpression of transferrin receptor, compared to respective control cell lines. Magnetic resonance imaging (MRI) of cancer cells treated with targeted IONPs with or without anti-biofouling PEG-b-AGE coating polymers demonstrated the target specific MRI contrast change using anti-biofouling PEG-b-AGE coated IONP with minimal off-targeted background compared to the IONPs without anti-biofouling coating, promising the highly efficient active targeting of nanoparticle imaging probes and drug delivery systems and potential applications of imaging quantification of targeted biomarkers. PMID:26594360

  20. PEG-b-AGE Polymer Coated Magnetic Nanoparticle Probes with Facile Functionalization and Anti-fouling Properties for Reducing Non-specific Uptake and Improving Biomarker Targeting.

    PubMed

    Li, Yuancheng; Lin, Run; Wang, Liya; Huang, Jing; Wu, Hui; Cheng, Guojun; Zhou, Zhengyang; MacDonald, Tobey; Yang, Lily; Mao, Hui

    2015-05-07

    Non-specific surface adsorption of bio-macromolecules (e.g. proteins) on nanoparticles, known as biofouling, and the uptake of nanoparticles by the mononuclear phagocyte system (MPS) and reticuloendothelial system (RES) lead to substantial reduction in the efficiency of target-directed imaging and delivery in biomedical applications of engineered nanomaterials in vitro and in vivo. In this work, a novel copolymer consisting of blocks of poly ethylene glycol and allyl glycidyl ether (PEG-b-AGE) was developed for coating magnetic iron oxide nanoparticles (IONPs) to reduce non-specific protein adhesion that leads to formation of "protein corona" and uptake by macrophages. The facile surface functionalization was demonstrated by using targeting ligands of a small peptide of RGD or a whole protein of transferrin (Tf). The PEG-b-AGE coated IONPs exhibited anti-biofouling properties with significantly reduced protein corona formation and non-specific uptake by macrophages before and after the surface functionalization, thus improving targeting of RGD-conjugated PEG-b-AGE coated IONPs to integrins in U87MG glioblastoma and MDA-MB-231 breast cancer cells that overexpress αvβ3 integrins, and Tf-conjugated PEG-b-AGE coated IONPs to transferrin receptor (TfR) in D556 and Daoy medulloblastoma cancer cells with high overexpression of transferrin receptor, compared to respective control cell lines. Magnetic resonance imaging (MRI) of cancer cells treated with targeted IONPs with or without anti-biofouling PEG-b-AGE coating polymers demonstrated the target specific MRI contrast change using anti-biofouling PEG-b-AGE coated IONP with minimal off-targeted background compared to the IONPs without anti-biofouling coating, promising the highly efficient active targeting of nanoparticle imaging probes and drug delivery systems and potential applications of imaging quantification of targeted biomarkers.

  1. Advanced manufacturing technologies for the BeCOAT telescope

    NASA Astrophysics Data System (ADS)

    Sweeney, Michael N.; Rajic, Slobodan; Seals, Roland D.

    1994-02-01

    The beryllium cryogenic off-axis telescope (BeCOAT) uses a two-mirror, non re-imaging, off- axis, Ritchey Chretian design with all-beryllium optics, structures and baffles. The purpose of this telescope is the system level demonstration of advanced manufacturing technologies for optics, optical benches, and baffle assemblies. The key issues that are addressed are single point diamond turning of beryllium optics, survivable fastening techniques, minimum beryllium utilization, and technologies leading to self-aligning, all-beryllium optical systems.

  2. Antifouling membranes for sustainable water purification: strategies and mechanisms.

    PubMed

    Zhang, Runnan; Liu, Yanan; He, Mingrui; Su, Yanlei; Zhao, Xueting; Elimelech, Menachem; Jiang, Zhongyi

    2016-10-24

    One of the greatest challenges to the sustainability of modern society is an inadequate supply of clean water. Due to its energy-saving and cost-effective features, membrane technology has become an indispensable platform technology for water purification, including seawater and brackish water desalination as well as municipal or industrial wastewater treatment. However, membrane fouling, which arises from the nonspecific interaction between membrane surface and foulants, significantly impedes the efficient application of membrane technology. Preparing antifouling membranes is a fundamental strategy to deal with pervasive fouling problems from a variety of foulants. In recent years, major advancements have been made in membrane preparation techniques and in elucidating the antifouling mechanisms of membrane processes, including ultrafiltration, nanofiltration, reverse osmosis and forward osmosis. This review will first introduce the major foulants and the principal mechanisms of membrane fouling, and then highlight the development, current status and future prospects of antifouling membranes, including antifouling strategies, preparation techniques and practical applications. In particular, the strategies and mechanisms for antifouling membranes, including passive fouling resistance and fouling release, active off-surface and on-surface strategies, will be proposed and discussed extensively.

  3. The effect of surface colour on the adhesion strength of Elminius modestus Darwin on a commercial non-biocidal antifouling coating at two locations in the UK.

    PubMed

    Robson, Martha A; Williams, David; Wolff, Kirsten; Thomason, Jeremy C

    2009-01-01

    A number of factors affect the adhesion strength of organisms to fouling-release coatings, and except for a few studies focussing on black or white surfaces none have dealt specifically with the effect of coating colour. The aim was to test the effect of colour on the adhesion strength of the barnacle Elminius modestus. Panels coated in six commercial colours of Intersleek 700 were submerged at two field sites and barnacles were pushed-off using a standard assay procedure. The strength of adhesion (SOA) varied between and within sites for colour and by barnacle basal area, SOA per unit area being higher for smaller barnacles. Higher SOA with a small basal area may be because of size-specific predation, differential hydrodynamic effects or adhesive failure with age. The complex effect of colour on barnacle adhesion may be because of physico-chemical surface characteristics varying with pigments, and their interactions with local environmental conditions, as well as interactions with the settling barnacle larvae.

  4. Research on chemical vapor deposition processes for advanced ceramic coatings

    NASA Technical Reports Server (NTRS)

    Rosner, Daniel E.

    1993-01-01

    Our interdisciplinary background and fundamentally-oriented studies of the laws governing multi-component chemical vapor deposition (VD), particle deposition (PD), and their interactions, put the Yale University HTCRE Laboratory in a unique position to significantly advance the 'state-of-the-art' of chemical vapor deposition (CVD) R&D. With NASA-Lewis RC financial support, we initiated a program in March of 1988 that has led to the advances described in this report (Section 2) in predicting chemical vapor transport in high temperature systems relevant to the fabrication of refractory ceramic coatings for turbine engine components. This Final Report covers our principal results and activities for the total NASA grant of $190,000. over the 4.67 year period: 1 March 1988-1 November 1992. Since our methods and the technical details are contained in the publications listed (9 Abstracts are given as Appendices) our emphasis here is on broad conclusions/implications and administrative data, including personnel, talks, interactions with industry, and some known applications of our work.

  5. 75 FR 24973 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Advanced Coatings...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-06

    ... Coatings for Infrastructure Joint Venture Agreement Notice is hereby given that, on March 10, 2010... seq. (``the Act''), Advanced Coatings for Infrastructure Joint Venture Agreement (``Advanced Coatings... identities of the parties to the venture are: MesoCoat Inc., Euclid, OH; Polythermics LLC, Kirkland, WA;...

  6. Preparation and Analysis of Type II Xerogel Films with Antifouling/Foul Release Characteristics

    NASA Astrophysics Data System (ADS)

    Sokolova, Anastasiya

    In order to combat biofouling, xerogel coatings comprised of aminopropyl, fluorocarbon, and hydrocarbon silanes were prepared and tested for their antifouling/foul release properties against Ulva, Navicula, barnacles, and tubeworms. Many of the coatings showed settlement and removal of Ulva to be as good as or better than the poly(dimethylsiloxane) (PDMSE) standard. Barnacle removal assays showed excellent results for some coatings while others did not fair so well. The best foul release coatings for barnacles were comprised of aminopropyl/hydrocarbon- and fluorocarbon/hydrocarbon-modified silanes. For the majority of coatings tested, water wettability and surface energy did not play a role in the antifouling/ foul release properties of the coatings.

  7. Advanced Porous Coating for Low-Density Ceramic Insulation Materials

    NASA Technical Reports Server (NTRS)

    Leiser, Daniel B.; Churchward, Rex; Katvala, Victor; Stewart, David; Balter, Aliza

    1988-01-01

    The need for improved coatings on low-density reusable surface insulation (RSI) materials used on the space shuttle has stimulated research into developing tougher coatings. The processing of a new porous composite "coating" for RST called toughened unipiece fibrous insulation Is discussed. Characteristics including performance in a simulated high-speed atmospheric entry, morphological structure before and after this exposure, resistance to Impact, and thermal response to a typical heat pulse are described. It is shown that this coating has improved impact resistance while maintaining optical and thermal properties comparable to the previously available reaction-cured glass coating.

  8. Antifouling activities of marine bacteria associated with sponge ( Sigmadocia sp.)

    NASA Astrophysics Data System (ADS)

    Satheesh, S.; Soniamby, A. R.; Sunjaiy Shankar, C. V.; Mary Josephine Punitha, S.

    2012-09-01

    The present study aimed at assessing the antifouling activity of bacteria associated with marine sponges. A total of eight bacterial strains were isolated from the surface of sponge Sigmadocia sp., of them, SS02, SS05 and SS06 showed inhibitory activity against biofilm-forming bacteria. The extracts of these 3 strains considerably affected the extracellular polymeric substance producing ability and adhesion of biofilm-forming bacterial strains. In addition to disc diffusion assay, microalgal settlement assay was carried out with the extracts mixed with polyurethane wood polish and coated onto stainless steel coupons. The extract of strain SS05 showed strong microalgal settlement inhibitory activity. Strain SS05 was identified as Bacillus cereus based on its 16S rRNA gene. Metabolites of the bacterial strains associated with marine invertebrates promise to be developed into environment-friendly antifouling agents.

  9. Influence of antifouling paint on freshwater invertebrates (Mytilidae, Chironomidae and Naididae): density, richness and composition.

    PubMed

    Fujita, D S; Takeda, A M; Coutinho, R; Fernandes, F C

    2015-11-01

    We conducted a study about invertebrates on artificial substrates with different antifouling paints in order to answer the following questions 1) is there lower accumulation of organic matter on substrates with antifouling paints, 2) is invertebrate colonization influenced by the release of biocides from antifouling paints, 3) is the colonization of aquatic invertebrates positively influenced by the material accumulated upon the substrate surface and 4) is the assemblage composition of invertebrates similar among the different antifouling paints? To answer these questions, four structures were installed in the Baía River in February 1st, 2007. Each structure was composed of 7 wood boards: 5 boards painted with each type of antifouling paints (T1, T2, T3, T4 and T5), one painted only with the primer (Pr) and the other without any paint (Cn). After 365 days, we observed a greater accumulation of organic matter in the substrates with T2 and T3 paint coatings. Limnoperna fortunei was recorded in all tested paints, with higher densities in the control, primer, T2 and T3. The colonization of Chironomidae and Naididae on the substrate was positively influenced by L. fortunei density. The non-metric multidimensional scaling (NMDS) of the invertebrate community provided evidence of the clear distinction of invertebrate assemblages among the paints. Paints T2 and T3 were the most similar to the control and primer. Our results suggest that antifouling paints applied on substrates hinder invertebrate colonization by decreasing the density and richness of invertebrates.

  10. Advanced thermal barrier coatings for operation in high hydrogen content fueled gas turbines.

    SciTech Connect

    Sampath, Sanjay

    2015-04-02

    The Center for Thermal Spray Research (CTSR) at Stony Brook University in partnership with its industrial Consortium for Thermal Spray Technology is investigating science and technology related to advanced metallic alloy bond coats and ceramic thermal barrier coatings for applications in the hot section of gasified coal-based high hydrogen turbine power systems. In conjunction with our OEM partners (GE and Siemens) and through strategic partnership with Oak Ridge National Laboratory (ORNL) (materials degradation group and high temperature materials laboratory), a systems approach, considering all components of the TBC (multilayer ceramic top coat, metallic bond coat & superalloy substrate) is being taken during multi-layered coating design, process development and subsequent environmental testing. Recent advances in process science and advanced in situ thermal spray coating property measurement enabled within CTSR has been incorporated for full-field enhancement of coating and process reliability. The development of bond coat processing during this program explored various aspects of processing and microstructure and linked them to performance. The determination of the bond coat material was carried out during the initial stages of the program. Based on tests conducted both at Stony Brook University as well as those carried out at ORNL it was determined that the NiCoCrAlYHfSi (Amdry) bond coats had considerable benefits over NiCoCrAlY bond coats. Since the studies were also conducted at different cycling frequencies, thereby addressing an associated need for performance under different loading conditions, the Amdry bond coat was selected as the material of choice going forward in the program. With initial investigations focused on the fabrication of HVOF bond coats and the performance of TBC under furnace cycle tests , several processing strategies were developed. Two-layered HVOF bond coats were developed to render optimal balance of density and surface roughness

  11. Thermal and Environmental Barrier Coating Development for Advanced Propulsion Engine Systems

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.; Fox, Dennis S.

    2008-01-01

    Ceramic thermal and environmental barrier coatings (TEBCs) are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments, and extend component lifetimes. Advanced TEBCs that have significantly lower thermal conductivity, better thermal stability and higher toughness than current coatings will be beneficial for future low emission and high performance propulsion engine systems. In this paper, ceramic coating design and testing considerations will be described for turbine engine high temperature and high-heat-flux applications. Thermal barrier coatings for metallic turbine airfoils and thermal/environmental barrier coatings for SiC/SiC ceramic matrix composite (CMC) components for future supersonic aircraft propulsion engines will be emphasized. Further coating capability and durability improvements for the engine hot-section component applications can be expected by utilizing advanced modeling and design tools.

  12. Development of Advanced Thermal and Environmental Barrier Coatings Using a High-Heat-Flux Testing Approach

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    2003-01-01

    The development of low conductivity, robust thermal and environmental barrier coatings requires advanced testing techniques that can accurately and effectively evaluate coating thermal conductivity and cyclic resistance at very high surface temperatures (up to 1700 C) under large thermal gradients. In this study, a laser high-heat-flux test approach is established for evaluating advanced low conductivity, high temperature capability thermal and environmental barrier coatings under the NASA Ultra Efficient Engine Technology (UEET) program. The test approach emphasizes the real-time monitoring and assessment of the coating thermal conductivity, which initially rises under the steady-state high temperature thermal gradient test due to coating sintering, and later drops under the cyclic thermal gradient test due to coating cracking/delamination. The coating system is then evaluated based on damage accumulation and failure after the combined steady-state and cyclic thermal gradient tests. The lattice and radiation thermal conductivity of advanced ceramic coatings can also be evaluated using laser heat-flux techniques. The external radiation resistance of the coating is assessed based on the measured specimen temperature response under a laser- heated intense radiation-flux source. The coating internal radiation contribution is investigated based on the measured apparent coating conductivity increases with the coating surface test temperature under large thermal gradient test conditions. Since an increased radiation contribution is observed at these very high surface test temperatures, by varying the laser heat-flux and coating average test temperature, the complex relation between the lattice and radiation conductivity as a function of surface and interface test temperature may be derived.

  13. Protection of Advanced Copper Alloys With Lean Cu-Cr Coatings

    NASA Technical Reports Server (NTRS)

    Greenbauer-Seng, L. (Technical Monitor); Thomas-Ogbuji, L.

    2003-01-01

    Advanced copper alloys are used as liners of rocket thrusters and nozzle ramps to ensure dissipation of the high thermal load generated during launch, and Cr-lean coatings are preferred for the protection of these liners from the aggressive ambient environment. It is shown that adequate protection can be achieved with thin Cu-Cr coatings containing as little as 17 percent Cr.

  14. Public Notice: Advanced Coatings Company Inc., CWA-01-2015-0034

    EPA Pesticide Factsheets

    Notice of Proposed Assessment of Class II Clean Water Act Section 309(g)(2)(B) and 311(b)(6)(B)(ii) Administrative Penalties and Opportunity to Comment for Advanced Coatings Company Inc., CWA-01-2015-0034

  15. Investigation of PACVD protective coating processes using advanced diagnostics techniques

    SciTech Connect

    Roman, W.C.

    1993-05-07

    Objective is to understand the mechanisms governing nonequilibrium plasma atomistic or molecular deposition of hard face coatings. Laser diagnostic methods include coherent anti-Stokes Raman spectroscopy (CARS) and laser-induced fluorescence. TiB[sub 2] and diamonds were used as the hard face coating materials. Diborane was used as precursor to TiB[sub 2].

  16. Advanced Thermal-Barrier Bond Coatings for Alloys

    NASA Technical Reports Server (NTRS)

    Secura, Stephen

    1987-01-01

    New and improved bond coatings developed for use in thermal-barrier systems on Ni, Co-, and Fe-base alloy substrates. Use of these new bond coatings, containing ytterbium instead of yttrium, significantly increased lives of resultant thermal-barrier systems. Uses include many load-bearing applications in high-temperature, hostile environments.

  17. Proceedings of the 1987 coatings for advanced heat engines workshop

    SciTech Connect

    Not Available

    1987-01-01

    This Workshop was conducted to enhance communication among those involved in coating development for improved heat engine performance and durability. We were fortunate to have Bill Goward review the steady progress and problems encountered along the way in the use of thermal barrier coatings (TBC) in aircraft gas turbine engines. Navy contractors discussed their work toward the elusive goal of qualifying TBC for turbine airfoil applications. In the diesel community, Caterpillar and Cummins are developing TBC for combustion chamber components as part of the low heat rejection diesel engine concept. The diesel engine TBC work is based on gas turbine technology with a goal of more than twice the thickness used on gas turbine engine components. Adoption of TBC in production for diesel engines could justify a new generation of plasma spray coating equipment. Increasing interests in tribology were evident in this Workshop. Coatings have a significant role in reducing friction and wear under greater mechanical loadings at higher temperatures. The emergence of a high temperature synthetic lubricant could have an enormous impact on diesel engine design and operating conditions. The proven coating processes such as plasma spray, electron-beam physical vapor deposition, sputtering, and chemical vapor deposition have shown enhanced capabilities, particularly with microprocessor controls. Also, the newer coating schemes such as ion implantation and cathodic arc are demonstrating intriguing potential for engine applications. Coatings will play an expanding role in higher efficiency, more durable heat engines.

  18. Advancement in Preparation of Hydroxyapatite/bioglass Graded Coatings by Electrophoretic Deposition

    NASA Astrophysics Data System (ADS)

    Yao, Liang; Chen, Chuanzhong; Wang, Diangang; Bao, Quanhe; Ma, Jie

    Electrophoretic deposition is a good method in the preparation of hydroxyapatite/bioglass graded coatings. Its processing parameters are easy to be operated. As it is nonbeeline process, it can be used in the deposition of complex shape and porous surface. This paper reviewed the advancement of the graded coatings in recent years, concluded the principles, characters, steps of electrophoretic deposition of bioceramic coatings and analyzed influencing factors in detail, such as granularity of suspension, aging of suspension, dispersion media, PH of suspension, electricity, voltage, deposition time, pretreatment of substrate and sintering. The foreground of hydroxyapatite/bioglass graded coatings is expected.

  19. Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna; Kiser, Doug; Wiesner, Valerie L.

    2016-01-01

    This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiCSiC Ceramic Matrix Composite (CMC) components for next generation turbine engines. The emphasis has been placed on the current design challenges of the 2700F environmental barrier coatings; coating processing and integration with SiCSiC CMCs and component systems; and performance evaluation and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements through advanced compositions and architecture designs, as shown in recent simulated engine high heat flux, combustion environment, in conjunction with mechanical creep and fatigue loading testing conditions.

  20. Advances in Thermal Spray Coatings for Gas Turbines and Energy Generation: A Review

    NASA Astrophysics Data System (ADS)

    Hardwicke, Canan U.; Lau, Yuk-Chiu

    2013-06-01

    Functional coatings are widely used in energy generation equipment in industries such as renewables, oil and gas, propulsion engines, and gas turbines. Intelligent thermal spray processing is vital in many of these areas for efficient manufacturing. Advanced thermal spray coating applications include thermal management, wear, oxidation, corrosion resistance, sealing systems, vibration and sound absorbance, and component repair. This paper reviews the current status of materials, equipment, processing, and properties' aspects for key coatings in the energy industry, especially the developments in large-scale gas turbines. In addition to the most recent industrial advances in thermal spray technologies, future technical needs are also highlighted.

  1. Progress in advanced high temperature turbine materials, coatings, and technology

    NASA Technical Reports Server (NTRS)

    Freche, J. C.; Ault, G. M.

    1977-01-01

    Material categories as well as coatings and recent turbine cooling developments are reviewed. Current state of the art is identified, and as assessment, when appropriate, of progress, problems, and future directions is provided.

  2. Advanced Antireflection Coatings for High-Performance Solar Energy Applications

    NASA Technical Reports Server (NTRS)

    Pan, Noren

    2015-01-01

    Phase II objectives: Develop and refine antireflection coatings incorporating lanthanum titanate as an intermediate refractive index material; Investigate wet/dry thermal oxidation of aluminum containing semiconductor compounds as a means of forming a more transparent window layer with equal or better optical properties than its unoxidized form; Develop a fabrication process that allows integration of the oxidized window layer and maintains the necessary electrical properties for contacting the solar cell; Conduct an experimental demonstration of the best candidates for improved antireflection coatings.

  3. Advanced Low Conductivity Thermal Barrier Coatings: Performance and Future Directions (Invited paper)

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    2008-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and performance will be emphasized. Advanced thermal barrier coatings have been developed using a multi-component defect clustering approach, and shown to have improved thermal stability and lower conductivity. The coating systems have been demonstrated for high temperature combustor applications. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the toughened thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion, impact and high heat-flux damage mechanisms of the thermal barrier coatings will also be described.

  4. Improve the performance of coated cemented hip stem through the advanced composite materials.

    PubMed

    Hedia, H S; Fouda, N

    2015-01-01

    Design of hip joint implant using functionally graded material (FGM) (advanced composite material) has been used before through few researches. It gives great results regarding the stress distribution along the implant and bone interfaces. However, coating of orthopaedic implants has been widely investigated through many researches. The effect of using advanced composite stem material, which mean by functionally graded stem material, in the total hip replacement coated with the most common coated materials has not been studied yet. Therefore, this study investigates the effect of utilizing these two concepts together; FGM and coating, in designing new stem material. It is concluded that the optimal FGM cemented stem is consisting from titanium at the upper stem layers graded to collagen at a lower stem layers. This optimal graded stem coated with hydroxyapatite found to reduce stress shielding by 57% compared to homogenous titanium stem coated with hydroxyapatite. However, the optimal functionally graded stem coated with collagen reduced the stress shielding by 51% compared to homogenous titanium stem coated with collagen.

  5. Antimicrobial nanospheres thin coatings prepared by advanced pulsed laser technique

    PubMed Central

    Holban, Alina Maria; Grumezescu, Valentina; Vasile, Bogdan Ştefan; Truşcă, Roxana; Cristescu, Rodica; Socol, Gabriel; Iordache, Florin

    2014-01-01

    Summary We report on the fabrication of thin coatings based on polylactic acid-chitosan-magnetite-eugenol (PLA-CS-Fe3O4@EUG) nanospheres by matrix assisted pulsed laser evaporation (MAPLE). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) investigation proved that the homogenous Fe3O4@EUG nanoparticles have an average diameter of about 7 nm, while the PLA-CS-Fe3O4@EUG nanospheres diameter sizes range between 20 and 80 nm. These MAPLE-deposited coatings acted as bioactive nanosystems and exhibited a great antimicrobial effect by impairing the adherence and biofilm formation of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) bacteria strains. Moreover, the obtained nano-coatings showed a good biocompatibility and facilitated the normal development of human endothelial cells. These nanosystems may be used as efficient alternatives in treating and preventing bacterial infections. PMID:24991524

  6. CVD Lu(2)O(3):Eu coatings For Advanced Scintillators.

    PubMed

    Topping, Stephen G; Sarin, V K

    2009-03-01

    Currently Lu(2)O(3):Eu(3+) scintillators can only be fabricated via hot-pressing and pixelization, which is commercially not viable, thus restricting their use. Chemical vapor deposition is being developed as an alternative manufacturing process. Columnar coatings of Lu(2)O(3):Eu(3+) have been achieved using the halide-CO(2)-H(2) system, clearly signifying feasibility of the CVD process. Characterization of the coatings using high resolution scanning electron microscopy (SEM) and x-ray diffraction (XRD) analysis have been used as an aid to optimize process parameters and attain highly oriented and engineered coating structures. These results have clearly demonstrated that this process can be successfully used to tailor sub-micron columnar growth of Lu(2)O(3):Eu(3+), with the potential of ultra high resolution x-ray imaging.

  7. Antimicrobial nanospheres thin coatings prepared by advanced pulsed laser technique.

    PubMed

    Holban, Alina Maria; Grumezescu, Valentina; Grumezescu, Alexandru Mihai; Vasile, Bogdan Ştefan; Truşcă, Roxana; Cristescu, Rodica; Socol, Gabriel; Iordache, Florin

    2014-01-01

    We report on the fabrication of thin coatings based on polylactic acid-chitosan-magnetite-eugenol (PLA-CS-Fe3O4@EUG) nanospheres by matrix assisted pulsed laser evaporation (MAPLE). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) investigation proved that the homogenous Fe3O4@EUG nanoparticles have an average diameter of about 7 nm, while the PLA-CS-Fe3O4@EUG nanospheres diameter sizes range between 20 and 80 nm. These MAPLE-deposited coatings acted as bioactive nanosystems and exhibited a great antimicrobial effect by impairing the adherence and biofilm formation of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) bacteria strains. Moreover, the obtained nano-coatings showed a good biocompatibility and facilitated the normal development of human endothelial cells. These nanosystems may be used as efficient alternatives in treating and preventing bacterial infections.

  8. Mechanical testing of advanced coating system, volume 1

    NASA Technical Reports Server (NTRS)

    Cruse, T. A.; Nagy, A.; Popelar, C. F.

    1990-01-01

    The Electron Beam Physical Vapor Deposition (EBPVD) coating material has a highly columnar microstructure, and as a result it was expected to have very low tensile strength. To be able to fabricate the required compression and tensile specimens, a substrate was required to provide structural integrity for the specimens. Substrate and coating dimensions were adjusted to provide sufficient sensitivity to resolve the projected loads carried by the EBPVD coating. The use of two distinctively different strain transducer systems, for tension and compression loadings, mandated two vastly different specimen geometries. Compression specimen and tensile specimen geometries are given. Both compression and tensile test setups are described. Data reduction mathematical models are given and discussed in detail as is the interpretation of the results. Creep test data is also given and discussed.

  9. A novel XRF method to measure environmental release of copper and zinc from antifouling paints.

    PubMed

    Ytreberg, Erik; Lagerström, Maria; Holmqvist, Albin; Eklund, Britta; Elwing, Hans; Dahlström, Magnus; Dahl, Peter; Dahlström, Mia

    2017-03-22

    The release of copper (Cu) and zinc (Zn) from vessels and leisure crafts coated with antifouling paints can pose a threat to water quality in semi-enclosed areas such as harbors and marinas as well as to coastal archipelagos. However, no reliable, practical and low-cost method exists to measure the direct release of metals from antifouling paints. Therefore, the paint industry and regulatory authorities are obliged to use release rate measurements derived from either mathematical models or from laboratory studies. To bridge this gap, we have developed a novel method using a handheld X-Ray Fluorescence spectrometer (XRF) to determine the cumulative release of Cu and Zn from antifouling paints. The results showed a strong linear relationship between XRF Kα net intensities and metal concentrations, as determined by ICP-MS. The release of Cu and Zn were determined for coated panels exposed in harbors located in the Baltic Sea and in Kattegat. The field study showed salinity to have a strong impact on the release of Cu, i.e. the release increased with salinity. Contrary, the effect of salinity on Zn was not as evident. As exemplified in this work, the XRF method also makes it possible to identify the governing parameters to the release of Cu and Zn, e.g. salinity and type of paint formulation. Thus, the XRF method can be used to measure environmentally relevant releases of metallic compounds to design more efficient and optimized antifouling coatings.

  10. Evaluation of anticorrosion and antifouling paint performance after exposure under seawater Surabaya-Madura (Suramadu) bridge

    NASA Astrophysics Data System (ADS)

    Nuraini, Lutviasari; Prifiharni, Siska; Priyotomo, Gadang; Sundjono, Gunawan, Hadi

    2017-03-01

    Antifouling paints are used widely to coat the underwater structures to prevent various fouling organisms. The evaluation of the performance for the two commercial anticorrosion and antifouling paints was carried out in the piles of Suramadu Bridge, East Java during 1 month exposure. The 20 cm width × 25 cm high × 0.3 cm thick specimens of mild steel were sandblasted and coated by anticorrosion and antifouling paint. Blank specimen (without exposed) were also prepared as a control. On the other hand, the 7.5 cm width × 15 cm high × 0.3 cm thick specimen bare mild steel was prepared for measure the corrosion rate throught weight loss method. The test panels containing specimens were exposure up to 1 month for immersion in splash zone and tidal zone (0, 1, 3, meters from sea level). Sea water parameters consisting of temperature, pH, salinity, conductivity and dissolved oxygen (DO) were also measured. The thickness, glossy, hardness and adhesion strength of the coating performance were carried out. The results show that both surfaces of anticorrosive paint and bare mild steel specimen covered by fouling organisms, whereas no fouling took place on the surface of antifouling paint. The corrosion rate of bare mild steel in the 0, 1, and 3 meters are 15.1;13.7 and 17.0 mpy, respectively.

  11. Advanced thermal barrier coating system development. Technical progress report

    SciTech Connect

    1996-06-10

    The objectives of the program are to provide an improved TBC system with increased temperature capability and improved reliability relative to current state of the art TBC systems. The development of such a coating system is essential to the ATS engine meeting its objectives. The base program consists of three phases: Phase 1: Program Planning--Complete; Phase 2: Development; Phase 3: Selected Specimen--Bench Test. Work is currently being performed in Phase 2 of the program. In Phase 2, process improvements will be married with new bond coat and ceramic materials systems to provide improvements over currently available TBC systems. Coating reliability will be further improved with the development of an improved lifing model and NDE techniques. This will be accomplished by conducting the following program tasks: II.1 Process Modeling; II.2 Bond Coat Development; II.3 Analytical Lifing Model; II.4 Process Development; II.5 NDE, Maintenance and Repair; II.6 New TBC Concepts. A brief summary is given of progress made in each of these 6 areas.

  12. Terahertz pulsed imaging as an advanced characterisation tool for film coatings--a review.

    PubMed

    Haaser, Miriam; Gordon, Keith C; Strachan, Clare J; Rades, Thomas

    2013-12-05

    Solid dosage forms are the pharmaceutical drug delivery systems of choice for oral drug delivery. These solid dosage forms are often coated to modify the physico-chemical properties of the active pharmaceutical ingredients (APIs), in particular to alter release kinetics. Since the product performance of coated dosage forms is a function of their critical coating attributes, including coating thickness, uniformity, and density, more advanced quality control techniques than weight gain are required. A recently introduced non-destructive method to quantitatively characterise coating quality is terahertz pulsed imaging (TPI). The ability of terahertz radiation to penetrate many pharmaceutical materials enables structural features of coated solid dosage forms to be probed at depth, which is not readily achievable with other established imaging techniques, e.g. near-infrared (NIR) and Raman spectroscopy. In this review TPI is introduced and various applications of the technique in pharmaceutical coating analysis are discussed. These include evaluation of coating thickness, uniformity, surface morphology, density, defects and buried structures as well as correlation between TPI measurements and drug release performance, coating process monitoring and scale up. Furthermore, challenges and limitations of the technique are discussed.

  13. Synthesis of advanced aluminide intermetallic coatings by low-energy Al-ion radiation

    PubMed Central

    Shen, Mingli; Gu, Yan; Zhao, Panpan; Zhu, Shenglong; Wang, Fuhui

    2016-01-01

    Metals that work at high temperatures (for instance, superalloys in gas-turbines) depend on thermally grown oxide (TGO, commonly alumina) to withstand corrosion attack. Nickel Aluminide (NiAl) as one superior alumina TGO former plays an important role in protective coatings for turbine blades in gas-turbine engines used for aircraft propulsion and power generation. Lowering TGO growth rate is essentially favored for offering sustainable protection, especially in thermal barrier coatings (TBC). However, it can only be achieved currently by a strategy of adding the third element (Pt or reactive elements) into NiAl during traditional diffusion- or deposition-based synthesis of the coating. Here we present a highly flexible Al-ion radiation-based synthesis of advanced NiAl coatings, achieving low TGO growth rate without relying on the third element addition. Our results expand the strategy for lowering TGO growth rate and demonstrate potentials for ion radiation in advancing materials synthesis. PMID:27194417

  14. Synthesis of advanced aluminide intermetallic coatings by low-energy Al-ion radiation

    NASA Astrophysics Data System (ADS)

    Shen, Mingli; Gu, Yan; Zhao, Panpan; Zhu, Shenglong; Wang, Fuhui

    2016-05-01

    Metals that work at high temperatures (for instance, superalloys in gas-turbines) depend on thermally grown oxide (TGO, commonly alumina) to withstand corrosion attack. Nickel Aluminide (NiAl) as one superior alumina TGO former plays an important role in protective coatings for turbine blades in gas-turbine engines used for aircraft propulsion and power generation. Lowering TGO growth rate is essentially favored for offering sustainable protection, especially in thermal barrier coatings (TBC). However, it can only be achieved currently by a strategy of adding the third element (Pt or reactive elements) into NiAl during traditional diffusion- or deposition-based synthesis of the coating. Here we present a highly flexible Al-ion radiation-based synthesis of advanced NiAl coatings, achieving low TGO growth rate without relying on the third element addition. Our results expand the strategy for lowering TGO growth rate and demonstrate potentials for ion radiation in advancing materials synthesis.

  15. Synthesis of advanced aluminide intermetallic coatings by low-energy Al-ion radiation.

    PubMed

    Shen, Mingli; Gu, Yan; Zhao, Panpan; Zhu, Shenglong; Wang, Fuhui

    2016-05-19

    Metals that work at high temperatures (for instance, superalloys in gas-turbines) depend on thermally grown oxide (TGO, commonly alumina) to withstand corrosion attack. Nickel Aluminide (NiAl) as one superior alumina TGO former plays an important role in protective coatings for turbine blades in gas-turbine engines used for aircraft propulsion and power generation. Lowering TGO growth rate is essentially favored for offering sustainable protection, especially in thermal barrier coatings (TBC). However, it can only be achieved currently by a strategy of adding the third element (Pt or reactive elements) into NiAl during traditional diffusion- or deposition-based synthesis of the coating. Here we present a highly flexible Al-ion radiation-based synthesis of advanced NiAl coatings, achieving low TGO growth rate without relying on the third element addition. Our results expand the strategy for lowering TGO growth rate and demonstrate potentials for ion radiation in advancing materials synthesis.

  16. Advanced Oxide Material Systems For 1650 C Thermal/Environmental Barrier Coating Applications

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Fox, Dennis S.; Bansal, Narottam P.; Miller, Robert A.

    2004-01-01

    Advanced thermal/environmental barrier coatings (T/EBCs) are being developed for low emission SiC/SiC ceramic matrix composite (CMC) combustor and vane applications to extend the CMC liner and vane temperature capability to 1650 C (3000 F) in oxidizing and water-vapor containing combustion environments. The 1650 C T/EBC system is required to have better thermal stability, lower thermal conductivity, and improved sintering and thermal stress resistance than current coating systems. In this paper, the thermal conductivity, water vapor stability and cyclic durability of selected candidate zirconia-/hafnia-, pyrochlore- and magnetoplumbite-based T/EBC materials are evaluated. The test results have been used to downselect the T/EBC coating materials, and help demonstrate advanced 1650OC coatings feasibility with long-term cyclic durability.

  17. Functionally gradient materials for thermal barrier coatings in advanced gas turbine systems

    SciTech Connect

    Banovic, S.W.; Barmak, K.; Chan, H.M.

    1995-10-01

    New designs for advanced gas turbine engines for power production are required to have higher operating temperatures in order to increase efficiency. However, elevated temperatures will increase the magnitude and severity of environmental degradation of critical turbine components (e.g. combustor parts, turbine blades, etc{hor_ellipsis}). To offset this problem, the usage of thermal barrier coatings (TBCs) has become popular by allowing an increase in maximum inlet temperatures for an operating engine. Although thermal barrier technology is over thirty years old, the principle failure mechanism is the spallation of the ceramic coating at or near the ceramic/bond coat interface. Therefore, it is desirable to develop a coating that combines the thermal barrier qualities of the ceramic layer and the corrosion protection by the metallic bond coat without the detrimental effects associated with the localization of the ceramic/metal interface to a single plane.

  18. Audio-band coating thermal noise measurement for Advanced LIGO with a multimode optical resonator

    NASA Astrophysics Data System (ADS)

    Gras, S.; Yu, H.; Yam, W.; Martynov, D.; Evans, M.

    2017-01-01

    In modern high precision optical instruments, such as in gravitational wave detectors or frequency references, thermally induced fluctuations in the reflective coatings can be a limiting noise source. This noise, known as coating thermal noise, can be reduced by choosing materials with low mechanical loss. Examination of new materials becomes a necessity in order to further minimize the coating thermal noise and thus improve sensitivity of next generation instruments. We present a novel approach to directly measure coating thermal noise using a high finesse folded cavity in which multiple Hermite-Gaussian modes coresonate. This method is used to probe surface fluctuations on the order 10-17 m /√{Hz } in the frequency range 30-400 Hz. We applied this technique to measure thermal noise and loss angle of the coating used in Advanced LIGO.

  19. Mechanical Properties and Durability of Advanced Environmental Barrier Coatings in Calcium-Magnesium-Alumino-Silicate Environments

    NASA Technical Reports Server (NTRS)

    Miladinovich, Daniel S.; Zhu, Dongming

    2011-01-01

    Environmental barrier coatings are being developed and tested for use with SiC/SiC ceramic matrix composite (CMC) gas turbine engine components. Several oxide and silicate based compositons are being studied for use as top-coat and intermediate layers in a three or more layer environmental barrier coating system. Specifically, the room temperature Vickers-indentation-fracture-toughness testing and high-temperature stability reaction studies with Calcium Magnesium Alumino-Silicate (CMAS or "sand") are being conducted using advanced testing techniques such as high pressure burner rig tests as well as high heat flux laser tests.

  20. Advanced Oxide Material Systems for 1650 C Thermal/Environmental Barrier Coating Applications

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming; Fox, Dennis S.; Bansal, Narottam P.; Miller, Robert A.

    2004-01-01

    Advanced thermal and environmental barrier coatings (TEBCs) are being developed for low-emission SiC/SiC ceramic matrix composite (CMC) combustor and vane applications to extend the CMC liner and vane temperature capability to 1650 C (3000 F) in oxidizing and water-vapor-containing combustion environments. The advanced 1650 C TEBC system is required to have a better high-temperature stability, lower thermal conductivity, and more resistance to sintering and thermal stress than current coating systems under engine high-heat-flux and severe thermal cycling conditions. In this report, the thermal conductivity and water vapor stability of selected candidate hafnia-, pyrochlore- and magnetoplumbite-based TEBC materials are evaluated. The effects of dopants on the materials properties are also discussed. The test results have been used to downselect the TEBC materials and help demonstrate the feasibility of advanced 1650 C coatings with long-term thermal cycling durability.

  1. Advanced Multi-Component Defect Cluster Oxide Doped Zirconia-Yttria Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    1990-01-01

    The advantages of using ceramic thermal barrier coatings in gas turbine engine hot sections include increased fuel efficiency and improved engine reliability. However, current thermal barrier coatings will not have the low thermal conductivity and necessary sintering resistance under higher operating temperatures and thermal gradients required by future advanced ultra-efficient and low-emission aircraft engines. In this paper, a novel oxide defect cluster design approach is described for achieving low thermal conductivity and excellent thermal stability of the thermal barrier coating systems. This approach utilizes multi-component rare earth and other metal cluster oxide dopants that are incorporated in the zirconia-yttria based systems, thus significantly reducing coating thermal conductivity and sintering resistance by effectively promoting the formation of thermodynamically stable, essentially immobile defect clusters and/or nanoscale phases. The performance of selected plasma-sprayed cluster oxide thermal barrier coating systems has been evaluated. The advanced multi-component thermal barrier coating systems were found to have significantly lower initial and long-term thermal conductivities, and better high temperature stability. The effect of oxide cluster dopants on coating thermal conductivity, sintering resistance, oxide grain growth behavior and durability will be discussed.

  2. Advanced Multi-Component Defect Cluster Oxide Doped Zirconia-Yttria Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    2003-01-01

    The advantages of using ceramic thermal barrier coatings in gas turbine engine hot sections include increased fuel efficiency and improved engine reliability. However, current thermal barrier coatings will not have the low thermal conductivity and necessary sintering resistance under higher operating temperatures and thermal gradients required by future advanced ultra efficient and low emission aircraft engines. In this paper, a novel oxide defect cluster design approach is described for achieving low thermal conductivity and excellent thermal stability of the thermal barrier coating systems. This approach utilizes multi-component rare earth and other metal cluster oxide dopants that are incorporated in the zirconia-yttna based systems, thus significantly reducing coating thermal conductivity and sintering resistance by effectively promoting the formation of thermodynamically stable, essentially immobile defect clusters and/or nanoscale phases. The performance of selected plasma-sprayed cluster oxide thermal barrier coating systems has been evaluated. The advanced multi-component thermal barrier coating systems were found to have significantly lower initial and long-term thermal conductivities, and better high temperature stability. The effect of oxide cluster dopants on coating thermal conductivity, sintering resistance, oxide grain growth behavior and durability will be discussed.

  3. Update on UCO's advanced coating lab development of silver-based mirror coatings

    NASA Astrophysics Data System (ADS)

    Phillips, Andrew C.; Fryauf, David M.; Kobayashi, Nobuhiko P.; DuPraw, Brian; Cheleden, Spencer; Ratliff, Christopher; Bolte, Michael J.; Cowley, David

    2016-08-01

    We present progress in efforts underway at the University of California Observatories to develop high performance durable silver-based mirror coatings for telescope and instruments. Silver-based coatings are extremely prone to tarnish and/or corrosion, and successful coatings depend not only on the materials used but also the deposition processes employed. Our physical vapor deposition (PVD) chamber allows both sputtering and ion-assisted e-beam depositions for head-to-head comparison of deposition processes, and we present results of these comparisons. In this paper, we review the problem and discuss our recent activities and findings. We discuss a systematic study to determine which oxides, nitrides and fluorides provide the best protection in environmental tests. We present initial results into the effects of stress in our specific thin films, and thee effects of stress on mirror coating durability. We also discuss studies using Atomic Layer Deposition (ALD) over-coating of Ag, and we describe a large ALD research chamber currently under construction that will demonstrate ALD processes on larger substrates (70 cm diameter).

  4. Innovative Superhard Materials and Sustainable Coatings for Advanced Manufacturing

    NASA Astrophysics Data System (ADS)

    Lee, Jay; Novikov, Nikolay

    The book contains the results of the latest achievements of leading researchers from 9 countries in the field of diamond and diamond-like carbon, cubic boron nitride and other superhard materials; high-density engineering ceramics; high pressure-high temperature technique; computer-aided modeling; diamond, cubic boron nitride, ceramic and cemented carbide tools; development, production and applications of nanostructured materials; films and wear-resistant coating; methods for quality control of tool materials and tools.

  5. Advanced Coatings from Natural-Based Polymers for Metals

    DTIC Science & Technology

    2000-07-01

    polysaccharide biopolymers originating from pectin, starch , and chitosan as renewable agricultural and marine resources, and on assessing their potential as the...excellent salt-spray resistance. 14. SUBJECT TERMS 15. NUMBER IF PAGES Coating, Corrosion, Aluminum, Biopolymer, Starch , Chitosan 7 16. PRICE CODE 17...The natural polymers used in this program were the corn-or potato- starch and crab or shrimp shells-chitosan obtained from renewable agricultural and

  6. A review of the recent advances in antimicrobial coatings for urinary catheters.

    PubMed

    Singha, Priyadarshini; Locklin, Jason; Handa, Hitesh

    2017-03-01

    More than 75% of hospital-acquired or nosocomial urinary tract infections are initiated by urinary catheters, which are used during the treatment of 15-25% of hospitalized patients. Among other purposes, urinary catheters are primarily used for draining urine after surgeries and for urinary incontinence. During catheter-associated urinary tract infections, bacteria travel up to the bladder and cause infection. A major cause of catheter-associated urinary tract infection is attributed to the use of non-ideal materials in the fabrication of urinary catheters. Such materials allow for the colonization of microorganisms, leading to bacteriuria and infection, depending on the severity of symptoms. The ideal urinary catheter is made out of materials that are biocompatible, antimicrobial, and antifouling. Although an abundance of research has been conducted over the last forty-five years on the subject, the ideal biomaterial, especially for long-term catheterization of more than a month, has yet to be developed. The aim of this review is to highlight the recent advances (over the past 10years) in developing antimicrobial materials for urinary catheters and to outline future requirements and prospects that guide catheter materials selection and design.

  7. Fabrication of advanced organic-inorganic nanocomposite coatings for biomedical applications by electrodeposition

    NASA Astrophysics Data System (ADS)

    Pang, Xin

    Novel electrodeposition strategies have been developed for the fabrication of thick adherent zirconia ceramic and composite coatings for biomedical applications. The new method is based on the electrophoretic deposition (EPD) of polyelectrolyte additives combined with the cathodic precipitation of zirconia. The method enables the room-temperature electrosynthesis of crystalline zirconia nanoparticles in the polymer matrix. Adherent crack-free coatings up to several microns thick were obtained. The deposits were studied by thermogravimetric and differential thermal analysis, X-ray diffraction analysis, scanning and transmission electron microscopy, and atomic force microscopy. Obtained results pave the way for electrodeposition of other ceramic-polymer composites. Novel advanced nanocomposite coatings based on bioceramic hydroxyapatite (HA) have been developed for the surface modification of orthopaedic and dental implant metals. HA nanopartic1es prepared by a chemical precipitation method were used for the fabrication of novel HA-chitosan nanocomposite coatings. The use of chitosan enables room-temperature fabrication of the composite coatings. The problems related to the sintering of HA can be avoided. A new electrodeposition strategy, based on the EPD of HA nanoparticles and electrochemical deposition of chitosan macromolecules, has been developed. The method enabled the formation of dense, adherent and uniform coatings of various thicknesses in the range of up to 60 mum. Bioactive composite coatings containing 40.9-89.8 wt% HA were obtained. The deposit composition and microstructure can be tailored by varying the chitosan and HA concentrations in the deposition bath. A mathematical model describing the formation of the HA-chitosan composite deposit has been developed. X-ray studies revealed preferred orientation of HA nanoparticles in the nanocomposites. Obtained coatings provide corrosion protection of the substrates and can be utilized for the fabrication of

  8. Advanced Coatings Enabling High Performance Instruments for Astrophysics Missions

    NASA Astrophysics Data System (ADS)

    Nikzad, Shouleh

    We propose a three-year effort to develop techniques for far-ultraviolet (FUV) and ultraviolet coatings both as reflective optics coatings and as out-of-band-rejection (solar-blind) filters that will have a dramatic effect on the throughput and efficiency of instruments. This is an ideal time to address this problem. On the one hand, exciting new science questions posed in UV and optical realm place exacting demands on instrument capabilities far beyond HST-COS, FUSE, and GALEX with large focal plane arrays and high efficiency requirements. And on the other hand, the development of techniques and process such as atomic layer deposition with its atomically precise capability and nano-engineered materials approach enables us to address the challenging materials issues in the UV where interaction of photons and matter happen in the first few nanometers of the material surface. Aluminum substrates with protective overlayers (typically XFy, where X = Li, Mg, or Ca) have been the workhorse of reflective coatings for ultraviolet and visible instruments; however, they have demonstrated severe limitations. The formation of oxide at the Al-XFy interface and thick protective layers both affect the overall optical performance, leading to diminished reflection at shorter wavelengths. To address these long-standing shortcomings of coatings, we will use our newly developed processes and equipment to produce high-quality single- and multi-layer films of a variety of dielectrics and metals deposited with nano-scale control. JPL s new ALD system affords high uniformity, low oxygen background, good plasma processes, and precise temperature control, which are vital to achieving the large scale, uniform, and ultrathin films that are free of oxygen at interfaces. For example, ALD-grown aluminum can be protected using our newly developed chemistry for ALD magnesium fluoride. Our work will verify that the ALD technique reliably prevents the oxidation of aluminum, and will subsequently be

  9. High Pressure Burner Rig Testing of Advanced Environmental Barrier Coatings for Si3N4 Turbine Components

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Fox, Dennis S.; Pastel, Robert T.

    2007-01-01

    Advanced thermal and environmental barrier coatings are being developed for Si3N4 components for turbine engine propulsion applications. High pressure burner rig testing was used to evaluate the coating system performance and durability. Test results demonstrated the feasibility and durability of the coating component systems under the simulated engine environments.

  10. Corrosion-Protection Coatings for Aluminum

    NASA Technical Reports Server (NTRS)

    Higgins, R. H.

    1983-01-01

    Study investigates 21 combinatios of surface treatments, primers and topcoats. Study considers several types of coatings, including primers, enamels, chlorinated rubbers, alkyds, epoxies, vinyls, polyurethanes, waterbased paints, and antifouling paints. 20-page report summarizes the study.

  11. Surface Diagnostics in Tribology Technology and Advanced Coatings Development

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1999-01-01

    This paper discusses the methodologies used for surface property measurement of thin films and coatings, lubricants, and materials in the field of tribology. Surface diagnostic techniques include scanning electron microscopy, transmission electron microscopy, atomic force microscopy, stylus profilometry, x-ray diffraction, electron diffraction, Raman spectroscopy, Rutherford backscattering, elastic recoil spectroscopy, and tribology examination. Each diagnostic technique provides specific measurement results in its own unique way. In due course it should be possible to coordinate the different pieces of information provided by these diagnostic techniques into a coherent self-consistent description of the surface properties. Examples are given on the nature and character of thin diamond films.

  12. Advances in flow visualization using liquid-crystal coatings

    NASA Technical Reports Server (NTRS)

    Holmes, Bruce J.; Obara, Clifford J.

    1987-01-01

    This paper discusses a new four-part mixing method for visualizing boundary layer flows, including transitions, separation, and shock locations, by the use of liquid-crystal coatings. The method controls the event temperature and color-play bandwidth best suited to specific experimental conditions, and is easily learned. The method is applicable almost throughout the altitude and speed ranges for subsonic aircraft flight envelopes, and is also applicable to supersonic flow visualization and for general use in high- and low-speed wind tunnel and water tunnel testing.

  13. Advanced Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: NASA's Perspectives

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming

    2016-01-01

    This presentation reviews NASA environmental barrier coating (EBC) system development programs and the coating materials evolutions for protecting the SiC/SiC Ceramic Matrix Composites in order to meet the next generation engine performance requirements. The presentation focuses on several generations of NASA EBC systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. The current EBC development emphasis is placed on advanced NASA 2700F candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance are described. The research and development opportunities for advanced turbine airfoil environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling are discussed.

  14. Advanced thermal barrier coating system development: Technical progress report

    SciTech Connect

    1996-08-07

    Objectives are to provide an improved TBC system with increased temperature capability and improved reliability, for the Advanced Turbine Systems program (gas turbine). The base program consists of three phases: Phase I, program planning (complete); Phase II, development; and Phase III (selected specimen-bench test). Work is currently being performed in Phase II.

  15. HYDROTHERMALLY SELF-ADVANCING HYBRID COATINGS FOR MITIGATING CORROSION OF CARBON STEEL.

    SciTech Connect

    SUGAMA, T.

    2006-11-22

    Hydrothermally self-advancing hybrid coatings were prepared by blending two starting materials, water-borne styrene acrylic latex (SAL) as the matrix and calcium aluminate cement (CAC) as the hydraulic filler, and then their usefulness was evaluated as the room temperature curable anti-corrosion coatings for carbon steel in CO{sub 2}-laden geothermal environments at 250 C. The following two major factors supported the self-improving mechanisms of the coating during its exposure in an autoclave: First was the formation of a high temperature stable polymer structure of Ca-complexed carboxylate groups containing SAL (Ca-CCG-SAL) due to hydrothermal reactions between SAL and CAC; second was the growth with continuing exposure time of crystalline calcite and boehmite phases coexisting with Ca-CCG-SAL. These two factors promoted the conversion of the porous microstructure in the non-autoclaved coating into a densified one after 7 days exposure. The densified microstructure not only considerably reduced the conductivity of corrosive ionic electrolytes through the coatings' layers, but also contributed to the excellent adherence of the coating to underlying steel' s surface that, in turn, retarded the cathodic oxygen reduction reaction at the corrosion site of steel. Such characteristics including the minimum uptake of corrosive electrolytes by the coating and the retardation of the cathodic corrosion reaction played an important role in inhibiting the corrosion of carbon steel in geothermal environments.

  16. Bio-inspired antifouling approaches: the quest towards non-toxic and non-biocidal materials.

    PubMed

    Nir, Sivan; Reches, Meital

    2016-06-01

    Biofouling is an undesirable process in which organisms and their by-products encrust a surface. Antifouling solutions are of great importance since biofouling has negative effects on numerous species, ecosystems, and areas including water treatment facilities, health-care systems, and marine devices. Many useful solutions have been developed in the last few decades. However, with the emergence of environmental issues, the search for new promising non-toxic materials has expanded. One approach tries to mimic natural antifouling surfaces and relies on mechanisms of action derived from nature. Since these materials are based on natural systems, they are mostly biocompatible and more efficient against complex fouling. In this review, we cover the latest advances in the field of antifouling materials. We specifically focus on biomaterials that are based on the chemical and physical behavior of biological systems.

  17. Anti-fouling bioactive surfaces.

    PubMed

    Yu, Qian; Zhang, Yanxia; Wang, Hongwei; Brash, John; Chen, Hong

    2011-04-01

    Bioactive surfaces refer to surfaces with immobilized bioactive molecules aimed specifically at promoting or supporting particular interactions. Such surfaces are of great importance for various biomedical and biomaterials applications. In the past few years, considerable effort has been made to create bioactive surfaces by forming specific biomolecule-modified surfaces on a non-biofouling "base" or "background". Hydrophilic and bioinert polymers have been widely used as anti-fouling layers that resist non-specific protein interactions. They can also serve as "spacers" to effectively move the immobilized biomolecule away from the surface, thus enhancing its bioactivity. In this review we summarize several successful approaches for the design and preparation of bioactive surfaces based on different types of anti-fouling/spacer materials. Some perspectives on future research in this area are also presented.

  18. Light-Emitting Diodes with Hierarchical and Multifunctional Surface Structures for High Light Extraction and an Antifouling Effect.

    PubMed

    Leem, Young-Chul; Park, Jung Su; Kim, Joon Heon; Myoung, NoSoung; Yim, Sang-Youp; Jeong, Sehee; Lim, Wantae; Kim, Sung-Tae; Park, Seong-Ju

    2016-01-13

    Bioinspired hierarchical structures on the surface of vertical light-emitting diodes (VLEDs) are demonstrated by combining a self-assembled dip-coating process and nanopatterning transfer method using thermal release tape. This versatile surface structure can efficiently reduce the total internal reflection and add functions, such as superhydrophobicity and high oleophobicity, to achieve an antifouling effect for VLEDs.

  19. Thermal barrier coatings issues in advanced land-based gas turbines

    NASA Technical Reports Server (NTRS)

    Parks, W. P.; Lee, W. Y.; Wright, I. G.

    1995-01-01

    The Department of Energy's Advanced Turbine System (ATS) program is aimed at forecasting the development of a new generation of land-based gas turbine systems with overall efficiencies significantly beyond those of current state-of-the-art machines, as well as greatly increased times between inspection and refurbishment, improved environmental impact, and decreased cost. The proposed duty cycle of ATS turbines will require the use of different criteria in the design of the materials for the critical hot gas path components. In particular, thermal barrier coatings will be an essential feature of the hot gas path components in these machines. While such coatings are routinely used in high-performance aircraft engines and are becoming established in land-based turbines, the requirements of the ATS turbine application are sufficiently different that significant improvements in thermal barrier coating technology will be necessary. In particular, it appears that thermal barrier coatings will have to function on all airfoil sections of the first stage vanes and blades to provide the significant temperature reduction required. In contrast, such coatings applied to the blades and vances of advanced aircraft engines are intended primarily to reduce air cooling requirements and extend component lifetime; failure of those coatings can be tolerated without jeopardizing mechanical or corrosion performance. A major difference is that in ATS turbines these components will be totally reliant on thermal barrier coatings which will, therefore, need to be highly reliable even over the leading edges of first stage blades. Obviously, the ATS program provides a very challenging opportunity for TBC's, and involves some significant opportunities to extend this technology.

  20. Hafnia-Based Nanostructured Thermal Barrier Coatings for Advanced Hydrogen Turbine Technology

    SciTech Connect

    Ramana, Chintalapalle; Choudhuri, Ahsan

    2013-01-31

    Thermal barrier coatings (TBCs) are critical technologies for future gas turbine engines of advanced coal based power generation systems. TBCs protect engine components and allow further increase in engine temperatures for higher efficiency. In this work, nanostructured HfO{sub 2}-based coatings, namely Y{sub 2}O{sub 3}-stabilized HfO{sub 2} (YSH), Gd{sub 2}O{sub 3}-stabilized HfO{sub 2} (GSH) and Y{sub 2}O{sub 3}-stabilized ZrO{sub 2}-HfO{sub 2} (YSZH) were investigated for potential TBC applications in hydrogen turbines. Experimental efforts are aimed at creating a fundamental understanding of these TBC materials. Nanostructured ceramic coatings of YSH, GSH and YSZH were grown by physical vapor deposition methods. The effects of processing parameters and ceramic composition on the microstructural evolution of YSH, GSH and YSZH nanostructured coatings was studied using combined X-ray diffraction (XRD) and Electron microscopy analyses. Efforts were directed to derive a detailed understanding of crystal-structure, morphology, and stability of the coatings. In addition, thermal conductivity as a function of composition in YSH, YSZH and GSH coatings was determined. Laboratory experiments using accelerated test environments were used to investigate the relative importance of various thermo-mechanical and thermo-chemical failure modes of TBCs. Effects of thermal cycling, oxidation and their complex interactions were evaluated using a syngas combustor rig.

  1. Nanocasting technique to prepare lotus-leaf-like superhydrophobic electroactive polyimide as advanced anticorrosive coatings.

    PubMed

    Chang, Kung-Chin; Lu, Hsin-I; Peng, Chih-Wei; Lai, Mei-Chun; Hsu, Sheng-Chieh; Hsu, Min-Hsiang; Tsai, Yuan-Kai; Chang, Chi-Hao; Hung, Wei-I; Wei, Yen; Yeh, Jui-Ming

    2013-02-01

    Nanocasting technique was used to obtain a biomimetic superhydrophobic electroactive polyimide (SEPI) surface structure from a natural Xanthosoma sagittifolium leaf. An electroactive polyimide (EPI) was first synthesized through thermal imidization. An impression of the superhydrophobic Xanthosoma sagittifolium leaf was then nanocasted onto the surface of the EPI so that the resulting EPI was superhydrophobic and would prevent corrosion. Polydimethylsiloxane (PDMS) was then used as a negative template to transfer the impression of the superhydrophobic surface of the biomimetic EPI onto a cold-rolled steel (CRS) electrode. The superhydrophobic electroactive material could be used as advanced coatings that protect metals against corrosion. The morphology of the surface of the as-synthesized SEPI coating was investigated using scanning electron microscopy (SEM). The surface showed numerous micromastoids, each decorated with many nanowrinkles. The water contact angle (CA) for the SEPI coating was 155°, which was significantly larger than that for the EPI coating (i.e., CA = 87°). The significant increase in the contact angle indicated that the biomimetic morphology effectively repelled water. Potentiodynamic and electrochemical impedance spectroscopic measurements indicated that the SEPI coating offered better protection against corrosion than the EPI coating did.

  2. Advanced, Non-Toxic, Anti-Corrosion, Anti-Fouling and Foul-Release Coatings Based on Covalently Attached Monolayers, Multilayers and Polymers

    DTIC Science & Technology

    2007-08-08

    McCarthy Polymer Science and Engineering Department, University of Massachusetts, Amherst, Massachusetts 01003 Electrophilic aromatic substitution reactions...with a fluorinated silane reagent. Reduction of the amide groups with borane-THF (BH 3-THF) complex leads to a 69% conversion of surface amides to the

  3. Progress in advanced high temperature turbine materials, coatings, and technology

    NASA Technical Reports Server (NTRS)

    Freche, J. C.; Ault, G. M.

    1977-01-01

    Several NASA-sponsored benefit-cost studies have shown that very substantial benefits can be obtained by increasing material capability for aircraft gas turbines. Prealloyed powder processing holds promise for providing superalloys with increased strength for turbine disk applications. The developement of advanced powder metallurgy disk alloys must be based on a design of optimum processing and heat treating procedures. Materials considered for high temperature application include oxide dispersion strengthened (ODS) alloys, directionally solidified superalloys, ceramics, directionally solidified eutectics, materials combining the high strength of a gamma prime strengthened alloy with the elevated temperature strength of an ODS, and composites. Attention is also given to the use of high pressure turbine seals, approaches for promoting environmental protection, and turbine cooling technology.

  4. Antifouling Electrospun Nanofiber Mats Functionalized with Polymer Zwitterions.

    PubMed

    Kolewe, Kristopher W; Dobosz, Kerianne M; Rieger, Katrina A; Chang, Chia-Chih; Emrick, Todd; Schiffman, Jessica D

    2016-10-06

    In this study, we exploit the excellent fouling resistance of polymer zwitterions and present electrospun nanofiber mats surface functionalized with poly(2-methacryloyloxyethyl phosphorylcholine) (polyMPC). This zwitterionic polymer coating maximizes the accessibility of the zwitterion to effectively limit biofouling on nanofiber membranes. Two facile, scalable methods yielded a coating on cellulose nanofibers: (i) a two-step sequential deposition featuring dopamine polymerization followed by the physioadsorption of polyMPC, and (ii) a one-step codeposition of polydopamine (PDA) with polyMPC. While the sequential and codeposited nanofiber mat assemblies have an equivalent average fiber diameter, hydrophilic contact angle, surface chemistry, and stability, the topography of nanofibers prepared by codeposition were smoother. Protein and microbial antifouling performance of the zwitterion modified nanofiber mats along with two controls, cellulose (unmodified) and PDA coated nanofiber mats were evaluated by dynamic protein fouling and prolonged bacterial exposure. Following 21 days of exposure to bovine serum albumin, the sequential nanofiber mats significantly resisted protein fouling, as indicated by their 95% flux recovery ratio in a water flux experiment, a 300% improvement over the cellulose nanofiber mats. When challenged with two model microbes Escherichia coli and Staphylococcus aureus for 24 h, both zwitterion modifications demonstrated superior fouling resistance by statistically reducing microbial attachment over the two controls. This study demonstrates that, by decorating the surfaces of chemically and mechanically robust cellulose nanofiber mats with polyMPC, we can generate high performance, free-standing nanofiber mats that hold potential in applications where antifouling materials are imperative, such as tissue engineering scaffolds and water purification technologies.

  5. Mimetic marine antifouling films based on fluorine-containing polymethacrylates

    NASA Astrophysics Data System (ADS)

    Sun, Qianhui; Li, Hongqi; Xian, Chunying; Yang, Yihang; Song, Yanxi; Cong, Peihong

    2015-07-01

    Novel methacrylate copolymers containing catechol and trifluoromethyl pendant side groups were synthesized by free radical polymerization of N-(3,4-dihydroxyphenyl)ethyl methacrylamide (DMA) and 2,2,2-trifluoroethyl methacrylate (TFME) with α,α‧-azobisisobutyronitrile (AIBN) as initiator. A series of copolymers with different content of TFME ranging from 3% to 95% were obtained by changing the molar ratio of DMA to TFME from 25:1 to 1:25. Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were used to characterize the copolymers, which displayed a certain degree of hardness and outstanding thermostability reflected from their high glass transition temperatures. The copolymers could adhere to surfaces of glass, plastics and metals due to introduction of catechol groups as multivalent hydrogen bonding anchors. Water contact angle on the polymer films was up to 117.4°. Chemicals resistance test manifested that the polymer films possessed excellent resistance to water, salt, acid and alkali. Moreover, the polymer films displayed fair antifouling property and might be used as promising environmentally friendly marine antifouling coatings.

  6. An Investigation of the Antifouling Potential of Extracts of the Periostracum of Mytilus sp.

    DTIC Science & Technology

    2011-07-01

    The 2008 International Maritime Organisation (IMO) global ban on Tributyltin ( TBT ) antifouling paints, together with growing concerns over potential...such as widely used vessel biocidal coatings containing the organotin ‘tributyltin’ ( TBT ), although efficacious against fouling, have limitations...relating to their toxicity (Anderson et al., 2003; Statz et al., 2006). The toxicity of TBT in the marine environment has been extensively researched

  7. Materials selection of surface coatings in an advanced size reduction facility. [For decommissioned stainless steel equipment

    SciTech Connect

    Briggs, J. L.; Younger, A. F.

    1980-06-02

    A materials selection test program was conducted to characterize optimum interior surface coatings for an advanced size reduction facility. The equipment to be processed by this facility consists of stainless steel apparatus (e.g., glove boxes, piping, and tanks) used for the chemical recovery of plutonium. Test results showed that a primary requirement for a satisfactory coating is ease of decontamination. A closely related concern is the resistance of paint films to nitric acid - plutonium environments. A vinyl copolymer base paint was the only coating, of eight paints tested, with properties that permitted satisfactory decontamination of plutonium and also performed equal to or better than the other paints in the chemical resistance, radiation stability, and impact tests.

  8. Advanced study of thermal behaviour of CSZ comparing with the classic YSZ coating

    NASA Astrophysics Data System (ADS)

    Dragomirescu, A.; Constantin, N.; Ştefan, A.; Manoliu, V.; Truşcă, R.

    2017-01-01

    Thermal barrier coatings (TBC) are advanced materials typically applied to metal surfaces subjected to extreme temperatures to protect them and increase their lifetime. Ceria stabilized zirconia ceramic layer (CSZ) is increasingly used as an alternative improved as replace for classical TBC system - yttria stabilized zirconia - thanks to superior properties, including mechanical and high resistance to thermal corrosion. The paper describes the thermal shock testing of two types of thermal barrier coatings used to protect a nickel super alloy. For the experimental procedure, it was used plate samples from nickel super alloy with a bond coat and a ceramic top coat. The top coat was different: on some samples, it was used YSZ and on others CSZ. Ni based super alloys have good corrosion resistance in reducing environments action, but poor in oxidizing conditions. Extreme environments can lead to loss of material by oxidation / corrosion, along with decreased mechanical properties of the substrate due to damaging elements which diffuses into the substrate at high temperatures. Using laboratory equipment, the TBC systems were exposed repeatedly to extreme high temperatures for a short time and then cooled. After the thermal shock tests, the samples were morph-structured characterized using electronic microscopy to analyze the changes. The experimental results were compared to rank the TBC systems in order of performance.

  9. Analytical investigation of thermal barrier coatings on advanced power generation gas turbines

    NASA Technical Reports Server (NTRS)

    Amos, D. J.

    1977-01-01

    An analytical investigation of present and advanced gas turbine power generation cycles incorporating thermal barrier turbine component coatings was performed. Approximately 50 parametric points considering simple, recuperated, and combined cycles (including gasification) with gas turbine inlet temperatures from current levels through 1644K (2500 F) were evaluated. The results indicated that thermal barriers would be an attractive means to improve performance and reduce cost of electricity for these cycles. A recommended thermal barrier development program has been defined.

  10. Hydrogel brushes grafted from stainless steel via surface-initiated atom transfer radical polymerization for marine antifouling

    NASA Astrophysics Data System (ADS)

    Wang, Jingjing; Wei, Jun

    2016-09-01

    Crosslinked hydrogel brushes were grafted from stainless steel (SS) surfaces for marine antifouling. The brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) respectively with different fractions of crosslinker in the feed. The grafted layers prepared with different thickness were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), ellipsometry and water contact angle measurements. With the increase in the fraction of crosslinker in the feed, the thickness of the grafted layer increased and the surface became smooth. All the brush-coated SS surfaces could effectively reduce the adhesion of bacteria and microalgae and settlement of barnacle cyprids, as compared to the pristine SS surface. The antifouling efficacy of the PEGMA polymer (PPEGMA)-grafted surface was higher than that of the MPC polymer (PMPC)-grafted surfaces. Furthermore, the crosslinked hydrogel brush-grafted surfaces exhibited better fouling resistance than the non-crosslinked polymer brush-grafted surfaces, and the antifouling efficacy increased with the crosslinking density. These hydrogel coatings of low toxicity and excellent anti-adhesive characteristics suggested their useful applications as environmentally friendly antifouling coatings.

  11. A degradable polydopamine coating based on disulfide-exchange reaction.

    PubMed

    Hong, Daewha; Lee, Hojae; Kim, Beom Jin; Park, Taegyun; Choi, Ji Yu; Park, Matthew; Lee, Juno; Cho, Hyeoncheol; Hong, Seok-Pyo; Yang, Sung Ho; Jung, Sun Ho; Ko, Sung-Bo; Choi, Insung S

    2015-12-21

    Although the programmed degradation of biocompatible films finds applications in various fields including biomedical and bionanotechnological areas, coating methods have generally been limited to be substrate-specific, not applicable to any kinds of substrates. In this paper, we report a dopamine derivative, which allows for both universal coating of various substrates and stimuli-responsive film degradation, inspired by mussel-adhesive proteins. Two dopamine moieties are linked together by the disulfide bond, the cleavage of which enables the programmed film degradation. Mechanistic analysis of the degradable films indicates that the initial cleavage of the disulfide linkage causes rapid uptake of water molecules, hydrating the films, which leads to rapid degradation. Our substrate-independent coating of degradable films provides an advanced tool for drug delivery systems, tissue engineering, and anti-fouling strategies.

  12. Hafnia-Based Materials Developed for Advanced Thermal/Environmental Barrier Coating Applications

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    2004-01-01

    Thermal and environmental barrier coatings (T/EBCs) will play a crucial role in advanced gas turbine engine systems because of their ability to significantly increase engine operating temperatures and reduce cooling requirements, and thus help achieve engine goals of low emissions and high efficiency. Under the NASA Ultra-Efficient Engine Technology (UEET) Project, advanced T/EBCs are being developed for low-emission SiC/SiC ceramic matrix composite (CMC) combustor applications by extending the CMC liner and vane temperature capability to 1650 C (3000 F) in oxidizing and water-vaporcontaining combustion environments. The coating system is required to have increased phase stability, lower lattice and radiation thermal conductivity, and improved sintering and thermal stress resistance under high-heat-flux and thermal-cycling engine conditions. Advanced heat-flux testing approaches (refs. 1 to 4) have been established at the NASA Glenn Research Center for 1650 C coating developments. The simulated combustion water-vapor environment is also being incorporated into the heat-flux test capabilities (ref. 3).

  13. DOD Initiatives to Rapidly Transition Advanced Coating and Surface Finishing Technologies for Military Turbine Engine Manufacture and Repair

    DTIC Science & Technology

    2005-03-21

    of PEWG Projects Involving Plating, Coating, and Surface Finishing • Advanced thermal spray coatings (HVOF) • Electrospark deposition • Laser...EWI, GEAE, P&W, Rolls-Royce FUNDING SOURCES RTOC STATUS OC-ALC request for FY06 Funding 3/21/2005 22 Other Technologies • Electrospark Deposition for...Aircraft Engines PEWG MANAGER Chuck Alford, Anteon Corp TECHNOLOGY OPPORTUNITY ADVANTAGES: Kinetic spray technologies deposit thick coatings with a

  14. Natural antifouling compounds: Effectiveness in preventing invertebrate settlement and adhesion.

    PubMed

    Almeida, Joana R; Vasconcelos, Vitor

    2015-01-01

    Biofouling represents a major economic issue regarding maritime industries and also raise important environmental concern. International legislation is restricting the use of biocidal-based antifouling (AF) coatings, and increasing efforts have been applied in the search for environmentally friendly AF agents. A wide diversity of natural AF compounds has been described for their ability to inhibit the settlement of macrofouling species. However poor information on the specific AF targets was available before the application of different molecular approaches both on invertebrate settlement strategies and bioadhesive characterization and also on the mechanistic effects of natural AF compounds. This review focuses on the relevant information about the main invertebrate macrofouler species settlement and bioadhesive mechanisms, which might help in the understanding of the reported effects, attributed to effective and non-toxic natural AF compounds towards this macrofouling species. It also aims to contribute to the elucidation of promising biotechnological strategies in the development of natural effective environmentally friendly AF paints.

  15. Protein antifouling and fouling-release in perfluoropolyether surfaces

    NASA Astrophysics Data System (ADS)

    Molena, Elena; Credi, Caterina; De Marco, Carmela; Levi, Marinella; Turri, Stefano; Simeone, Giovanni

    2014-08-01

    Perfluoropolyether polymers have been described as high performance fouling-release materials for marine coatings. Moreover, they have a good potential to be exploited in the biomedical field too. In this article several perfuoropolyether photopolymers were characterized in terms of surface and mechanical properties outlining the relationship between these properties and the polymer molecular structure. In particular the anti-fouling and fouling-release performances, evaluated using Bovine Serum Albumin as testing protein, was correlated to other material properties, like a parameter considering both surface tension components γ and elastic modulus E. A good correlation between the anti-fouling/fouling-release of perfluoropolyethers and (E*γpolar)1/2 can actually be established. Our results show that perfluoropolyether photopolymers are good protein anti-fouling/fouling-release materials.

  16. Coatings.

    ERIC Educational Resources Information Center

    Anderson, Dennis G.

    1989-01-01

    This review covers analytical techniques applicable to the examination of coatings, raw materials, and substrates upon which coatings are placed. Techniques include chemical and electrochemical methods, chromatography, spectroscopy, thermal analysis, microscopy, and miscellaneous techniques. (MVL)

  17. A degradable polydopamine coating based on disulfide-exchange reaction

    NASA Astrophysics Data System (ADS)

    Hong, Daewha; Lee, Hojae; Kim, Beom Jin; Park, Taegyun; Choi, Ji Yu; Park, Matthew; Lee, Juno; Cho, Hyeoncheol; Hong, Seok-Pyo; Yang, Sung Ho; Jung, Sun Ho; Ko, Sung-Bo; Choi, Insung S.

    2015-11-01

    Although the programmed degradation of biocompatible films finds applications in various fields including biomedical and bionanotechnological areas, coating methods have generally been limited to be substrate-specific, not applicable to any kinds of substrates. In this paper, we report a dopamine derivative, which allows for both universal coating of various substrates and stimuli-responsive film degradation, inspired by mussel-adhesive proteins. Two dopamine moieties are linked together by the disulfide bond, the cleavage of which enables the programmed film degradation. Mechanistic analysis of the degradable films indicates that the initial cleavage of the disulfide linkage causes rapid uptake of water molecules, hydrating the films, which leads to rapid degradation. Our substrate-independent coating of degradable films provides an advanced tool for drug delivery systems, tissue engineering, and anti-fouling strategies.Although the programmed degradation of biocompatible films finds applications in various fields including biomedical and bionanotechnological areas, coating methods have generally been limited to be substrate-specific, not applicable to any kinds of substrates. In this paper, we report a dopamine derivative, which allows for both universal coating of various substrates and stimuli-responsive film degradation, inspired by mussel-adhesive proteins. Two dopamine moieties are linked together by the disulfide bond, the cleavage of which enables the programmed film degradation. Mechanistic analysis of the degradable films indicates that the initial cleavage of the disulfide linkage causes rapid uptake of water molecules, hydrating the films, which leads to rapid degradation. Our substrate-independent coating of degradable films provides an advanced tool for drug delivery systems, tissue engineering, and anti-fouling strategies. Electronic supplementary information (ESI) available: Synthesis, characterization, and other additional details. See DOI: 10

  18. Erosion Coatings for High-Temperature Polymer Composites: A Collaborative Project With Allison Advanced Development Company

    NASA Technical Reports Server (NTRS)

    Sutter, James K.

    2000-01-01

    composite (ASTM D 4541 95 "Pull Off Strength of Coatings"). Glenn and Allison Advanced Development Company collaborated to optimize erosion coatings for gas turbine fan and compressor applications. All the coating systems survived aggressive thermal cycling without spalling. During erosion tests (see the final photo), the most promising coating systems tested had Cr3C2-NiCr and WC-Co as the hard topcoats. In all cases, these coating systems performed significantly better than that with a TiN hard topcoat. When material depth (thickness) loss is considered, the Cr3C2-NiCr and WC-Co coating systems provided, on average, an erosion resistance 8.5 times greater than that for the uncoated PMR 15/T650 35 composite. Similarly, Cr3C2-NiCr and WC-Co coating systems adhered to the PMC substrate during tensile tests significantly better than systems containing a TiN topcoat. Differences in topcoats of Cr3C2-NiCr and WC-Co were determined by considering issues such as cost and environmental impact. The preferred erosion-resistant coating system for PMR 15/T650 35 has WC-Co as the hard topcoat. This system provides the following benefits in comparison to the coating system with Cr3C2-NiCr topcoat: lower powder material cost (15 to 20 percent), environmentally friendly materials (Cr3C2-NiCr is hazardous), and higher deposition yield (10 to 15 percent), which results in less waste.

  19. ­A practical application of reduced-copper antifouling paint in marine biological research

    PubMed Central

    2016-01-01

    Biofouling of experimental cages and other field apparatuses can be problematic for scientists and has traditionally been addressed using frequent manual removal (e.g., scraping, scrubbing). Recent environmental restrictions and legislative changes have driven the development of less hazardous antifouling products, making antifouling paint a potential alternative option to manual removal. Consequently, the viability of using these newly developed products as a replacement for the manual cleaning of exclusion cages was experimentally investigated. There were six treatments tested, comprising three with settlement tiles in experimental cages coated with antifouling paint, two with settlement tiles in unpainted experimental cages, and one cage-free suspended tile. The three antifouling treatments comprised two reduced-copper paints (21% Cu2O and 40% Cu2O) and one copper-free, Econea™-based paint (labeled “ecofriendly”). Antifouling paints were assessed for performance of preventing fouling of the cages and whether they elicited local effects on settlement tiles contained within them. All three paints performed well to reduce fouling of the cages during the initial six weeks of the experiment, but the efficacy of “ecofriendly” paint began to decrease during an extended deployment that lasted 14 weeks. The macro-community composition, biomass, and percent cover of settled organism on tiles within cages treated with copper-based paints (21% and 40% concentrations) were indistinguishable from tiles within the manually scrubbed cages. In contrast, settlement to tiles from the “ecofriendly” treatment was different in composition of macro-community and lower in biomass, suggesting the presence of local effects and therefore rendering it unsuitable for use in settlement experiments. The results of this study suggest that reduced-copper paints have the potential to serve as an alternative to manual maintenance, which may be useful for deployments in locations

  20. Universal Surface-initiated Polymerization of Antifouling Zwitterionic Brushes Using A Mussel-Mimetic Peptide Initiator

    PubMed Central

    Kuang, Jinghao; Messersmith, Phillip B.

    2012-01-01

    We report a universal method for the surface-initated polymerization (SIP) of a antifouling polymer brush on various classes of surfaces, including noble metals, metal oxides and inert polymers. Inspired by the versatility of mussel adhesive proteins, we synthesized a novel bifunctional tripeptide bromide (BrYKY) which combines an atom transfer radical polymerization (ATRP) initiating alkyl bromide with l-3,4-dihydroxyphenylalanine (DOPA) and lysine. Simple dip-coating of substrates with variable wetting properties and compositions, including Teflon®, in a BrYKY solution at pH 8.5 led to formation of a thin film of cross-linked BrYKY. Subsequently, we showed that the BrYKY layer initiated the ATRP of a zwitterionic monomer, sulfobetaine methacrylate (SBMA) on all substrates, resulting in high density antifouling pSBMA brushes. Both BrYKY deposition and pSBMA grafting were unambiguously confirmed by ellipsometry, X-ray photoelectron spectroscopy and goniometry. All substrates that were coated with BrYKY/pSBMA dramatically reduced bacterial adhesion for 24 h and also resisted mammalian cell adhesion for at least 4 months, demonstrating the long-term stability of the BrYKY anchoring and antifouling properties of pSBMA. The use of BrYKY as a primer and polymerization initiator has the potential to be widely employed in surface grafted polymer brush modifications for biomedical and other applications. PMID:22506651

  1. Advanced thermal barrier coating system development. Technical progress report, June 1, 1996--July 31, 1996

    SciTech Connect

    1996-08-07

    An improved thermal barrier coating system with good reliability and thermal performance is described. The report discusses the coating process, manufacturing, repair, deposition, and microstructure of the coatings.

  2. Plasma-enhanced deposition of antifouling layers on silicone rubber surfaces

    NASA Astrophysics Data System (ADS)

    Jiang, Hongquan

    In food processing and medical environments, biofilms serve as potential sources of contamination, and lead to food spoilage, transmission of diseases or infections. Because of its ubiquitous and recalcitrant nature, Listeria monocytogenes biofilm is especially hard to control. Generating antimicrobial surfaces provide a method to control the bacterial attachment. The difficulty of silver deposition on polymeric surfaces has been overcome by using a unique two-step plasma-mediated method. First silicone rubber surfaces were plasma-functionalized to generate aldehyde groups. Then thin silver layers were deposited onto the functionalized surfaces according to Tollen's reaction. X-ray photoelectron spectroscopy (XPS), atomic force spectroscopy (AFM) and scanning electron microscopy (SEM) showed that silver particles were deposited. By exposing the silver coated surfaces to L. monocytogenes, it was demonstrated that they were bactericidal to L. monocytogenes. No viable bacteria were detected after 12 to 18 h on silver-coated silicone rubber surfaces. Another antifouling approach is to generate polyethylene glycol (PEG) thin layer instead of silver on polymer surfaces. Covalent bond of PEG structures of various molecular weights to cold-plasma-functionalized polymer surfaces, such as silicone rubber, opens up a novel way for the generation of PEG brush-like or PEG branch-like anti-fouling layers. In this study, plasma-generated surface free radicals can react efficiently with dichlorosilane right after plasma treatment. With the generation of halo-silane groups, this enables PEG molecules to be grafted onto the modified surfaces. XPS data clearly demonstrated the presence of PEG molecules on plasma-functionalized silicone rubber surfaces. AFM images showed the changed surface morphologies as a result of covalent attachment to the surface of PEG molecules. Biofilm experiment results suggest that the PEG brush-like films have the potential ability to be the next

  3. Antifouling Transparent ZnO Thin Films Fabricated by Atmospheric Pressure Cold Plasma Deposition

    NASA Astrophysics Data System (ADS)

    Suzaki, Yoshifumi; Du, Jinlong; Yuji, Toshifumi; Miyagawa, Hayato; Ogawa, Kazufumi

    2015-09-01

    One problem with outdoor-mounted solar panels is that power generation efficiency is reduced by face plate dirt; a problem with electronic touch panels is the deterioration of screen visibility caused by finger grease stains. To solve these problems, we should fabricate antifouling surfaces which have superhydrophobic and oil-repellent properties without spoiling the transparency of the transparent substrate. In this study, an antifouling surface with both superhydrophobicity and oil-repellency was fabricated on a glass substrate by forming a fractal microstructure. The fractal microstructure was constituted of transparent silica particles 100 nm in diameter and transparent zinc-oxide columns grown on silica particles through atmospheric pressure cold plasma deposition; the sample surface was coated with a chemically adsorbed monomolecular layer. Samples were obtained which had a superhydrophobic property (with a water droplet contact angle of more than 150°) and a high average transmittance of about 90% (with wavelengths ranging from 400 nm to 780 nm).

  4. Novel antifouling oligo(ethylene glycol) methacrylate particles via surfactant-free emulsion polymerization.

    PubMed

    Buyukserin, Fatih; Camli, Sevket Tolga; Yavuz, Mustafa Selman; Budak, Gurer Guven

    2011-03-01

    The use of particle formulations with antifouling surface properties attracts increasing interest in several biotechnological applications. Majority of these studies utilize a poly(ethylene glycol) coating to render the corresponding surface nonrecognizable to biological macromolecules. Herein, we report a simple way to prepare novel antifouling colloids composed of oligo(ethylene glycol) backbones via surfactant-free emulsion polymerization. Monodisperse cross-linked poly(ethylene glycol) ethyl ether methacrylate particles were characterized by dynamic light scattering and transmission electron microscopy. The effects of monomer, cross-linker and initiator on particle characteristics were investigated. More importantly, a prominent blockage of bovine serum albumin adsorption was obtained for the poly(ethylene glycol)-based sub-micron (~200 nm) particles when compared with similar-sized poly(methyl methacrylate) counterparts.

  5. Risks of Using Antifouling Biocides in Aquaculture

    PubMed Central

    Guardiola, Francisco Antonio; Cuesta, Alberto; Meseguer, José; Esteban, Maria Angeles

    2012-01-01

    Biocides are chemical substances that can deter or kill the microorganisms responsible for biofouling. The rapid expansion of the aquaculture industry is having a significant impact on the marine ecosystems. As the industry expands, it requires the use of more drugs, disinfectants and antifoulant compounds (biocides) to eliminate the microorganisms in the aquaculture facilities. The use of biocides in the aquatic environment, however, has proved to be harmful as it has toxic effects on the marine environment. Organic booster biocides were recently introduced as alternatives to the organotin compounds found in antifouling products after restrictions were imposed on the use of tributyltin (TBT). The replacement products are generally based on copper metal oxides and organic biocides. The biocides that are most commonly used in antifouling paints include chlorothalonil, dichlofluanid, DCOIT (4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, Sea-nine 211®), Diuron, Irgarol 1051, TCMS pyridine (2,3,3,6-tetrachloro-4-methylsulfonyl pyridine), zinc pyrithione and Zineb. There are two types of risks associated with the use of biocides in aquaculture: (i) predators and humans may ingest the fish and shellfish that have accumulated in these contaminants and (ii) the development of antibiotic resistance in bacteria. This paper provides an overview of the effects of antifouling (AF) biocides on aquatic organisms. It also provides some insights into the effects and risks of these compounds on non-target organisms. PMID:22408407

  6. Risks of using antifouling biocides in aquaculture.

    PubMed

    Guardiola, Francisco Antonio; Cuesta, Alberto; Meseguer, José; Esteban, Maria Angeles

    2012-01-01

    Biocides are chemical substances that can deter or kill the microorganisms responsible for biofouling. The rapid expansion of the aquaculture industry is having a significant impact on the marine ecosystems. As the industry expands, it requires the use of more drugs, disinfectants and antifoulant compounds (biocides) to eliminate the microorganisms in the aquaculture facilities. The use of biocides in the aquatic environment, however, has proved to be harmful as it has toxic effects on the marine environment. Organic booster biocides were recently introduced as alternatives to the organotin compounds found in antifouling products after restrictions were imposed on the use of tributyltin (TBT). The replacement products are generally based on copper metal oxides and organic biocides. The biocides that are most commonly used in antifouling paints include chlorothalonil, dichlofluanid, DCOIT (4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, Sea-nine 211(®)), Diuron, Irgarol 1051, TCMS pyridine (2,3,3,6-tetrachloro-4-methylsulfonyl pyridine), zinc pyrithione and Zineb. There are two types of risks associated with the use of biocides in aquaculture: (i) predators and humans may ingest the fish and shellfish that have accumulated in these contaminants and (ii) the development of antibiotic resistance in bacteria. This paper provides an overview of the effects of antifouling (AF) biocides on aquatic organisms. It also provides some insights into the effects and risks of these compounds on non-target organisms.

  7. A Method for Evaluating the Efficacy of Antifouling Paints Using Mytilus galloprovincialis in the Laboratory in a Flow-Through System

    PubMed Central

    Satuito, Cyril Glenn Perez; Katsuyama, Ichiro; Ando, Hirotomo; Seki, Yasuyuki; Senda, Tetsuya

    2016-01-01

    A laboratory test with a flow-through system was designed and its applicability for testing antifouling paints of varying efficacies was investigated. Six different formulations of antifouling paints were prepared to have increasing contents (0 to 40 wt.%) of Cu2O, which is the most commonly used antifouling substance, and each formulation of paint was coated on just one surface of every test plate. The test plates were aged for 45 days by rotating them at a speed of 10 knots inside a cylinder drum. A behavioral test was then conducted using five mussels (Mytilus galloprovincialis) that were pasted onto the coated surface of each aged test plate. The number of the byssus threads produced by each mussel generally decreased with increasing Cu2O content of the paint. The newly designed method was considered valid owing to the high consistency of its results with observations from the field experiment. PMID:27959916

  8. Development of processing procedures for advanced silicon solar cells. [antireflection coatings and short circuit currents

    NASA Technical Reports Server (NTRS)

    Scott-Monck, J. A.; Stella, P. M.; Avery, J. E.

    1975-01-01

    Ten ohm-cm silicon solar cells, 0.2 mm thick, were produced with short circuit current efficiencies up to thirteen percent and using a combination of recent technical advances. The cells were fabricated in conventional and wraparound contact configurations. Improvement in cell collection efficiency from both the short and long wavelengths region of the solar spectrum was obtained by coupling a shallow junction and an optically transparent antireflection coating with back surface field technology. Both boron diffusion and aluminum alloying techniques were evaluated for forming back surface field cells. The latter method is less complicated and is compatible with wraparound cell processing.

  9. Environmental management aspects for TBT antifouling wastes from the shipyards.

    PubMed

    Kotrikla, Anna

    2009-02-01

    Tributyltin (TBT)-based antifouling paints have been successfully used for over 40 years to protect a ship's hull from biofouling. However, due to its high toxicity to marine organisms, the International Maritime Organization (IMO), in 1990, adopted a resolution recommending governments to adopt measures to eliminate antifouling paints containing TBT. High concentrations of TBT are detected in the vicinity of ports and shipyards. TBT is also usually detected in the sediment, in which it accumulates. This study reviews recent literature for the best management practices (BMPs) in order to minimize the environmental effects of TBT. The paper focuses on the evaluation of the available techniques for the removal of TBT from shipyard wastes and from the sediment. The most effective treatment methods are highlighted. BMPs include recycling of abrasive materials, use of cleaner abrasive materials, reuse of spent abrasive materials, substitution of hydroblasting by vacuum blasting or containment or ultra-high-pressure water blasting and confinement of pollution by enclosure and containment systems. The treatment of the TBT wastes by conventional biological wastewater treatment processes is probably not suitable, because the concentrations of TBT found in shipyards' wastewaters are toxic to microorganisms. Advanced technologies such as activated carbon adsorption and dissolved air flotation, in combination with filtration and coagulation-clarification, photodegradation and electrochemical treatment, are required to remove TBT. However, advanced methods should be further optimized to meet the regulatory limit of 200 ng/L. To date, only one published work examines the efficiency of incineration for the treatment of solid sandblast wastes. Regarding the treatment of sediment, land deposition of the less polluted fraction of sediment is a feasible option. Such treatment must take into account the risk of contamination of groundwater and the surroundings, and it requires

  10. An Assessment of the Residual Stresses in Low Pressure Plasma Sprayed Coatings on an Advanced Copper Alloy

    NASA Technical Reports Server (NTRS)

    Raj, S. V.; Ghosn, L. J.; Agarwal, A.; Lachtrupp, T. P.

    2002-01-01

    Modeling studies were conducted on low pressure plasma sprayed (LPPS) NiAl top coat applied to an advanced Cu-8(at.%)Cr-4%Nb alloy (GRCop-84) substrate using Ni as a bond coat. A thermal analysis suggested that the NiAl and Ni top and bond coats, respectively, would provide adequate thermal protection to the GRCop-84 substrate in a rocket engine operating under high heat flux conditions. Residual stress measurements were conducted at different depths from the free surface on coated and uncoated GRCop-84 specimens by x-ray diffraction. These data are compared with theoretically estimated values assessed by a finite element analysis simulating the development of these stresses as the coated substrate cools down from the plasma spraying temperature to room temperature.

  11. Transparent antifouling material for improved operative field visibility in endoscopy

    PubMed Central

    Sunny, Steffi; Cheng, George; Daniel, Daniel; Lo, Peter; Ochoa, Sebastian; Howell, Caitlin; Vogel, Nicolas; Majid, Adnan; Aizenberg, Joanna

    2016-01-01

    Camera-guided instruments, such as endoscopes, have become an essential component of contemporary medicine. The 15–20 million endoscopies performed every year in the United States alone demonstrate the tremendous impact of this technology. However, doctors heavily rely on the visual feedback provided by the endoscope camera, which is routinely compromised when body fluids and fogging occlude the lens, requiring lengthy cleaning procedures that include irrigation, tissue rubbing, suction, and even temporary removal of the endoscope for external cleaning. Bronchoscopies are especially affected because they are performed on delicate tissue, in high-humidity environments with exposure to extremely adhesive biological fluids such as mucus and blood. Here, we present a repellent, liquid-infused coating on an endoscope lens capable of preventing vision loss after repeated submersions in blood and mucus. The material properties of the coating, including conformability, mechanical adhesion, transparency, oil type, and biocompatibility, were optimized in comprehensive in vitro and ex vivo studies. Extensive bronchoscopy procedures performed in vivo on porcine lungs showed significantly reduced fouling, resulting in either unnecessary or ∼10–15 times shorter and less intensive lens clearing procedures compared with an untreated endoscope. We believe that the material developed in this study opens up opportunities in the design of next-generation endoscopes that will improve visual field, display unprecedented antibacterial and antifouling properties, reduce the duration of the procedure, and enable visualization of currently unreachable parts of the body, thus offering enormous potential for disease diagnosis and treatment. PMID:27688761

  12. Thermal Conductivity of Advanced Ceramic Thermal Barrier Coatings Determined by a Steady-state Laser Heat-flux Approach

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming; Miller, Robert A.

    2004-01-01

    The development of low conductivity and high temperature capable thermal barrier coatings requires advanced testing techniques that can accurately and effectively evaluate coating thermal conductivity under future high-performance and low-emission engine heat-flux conditions. In this paper, a unique steady-state CO2 laser (wavelength 10.6 microns) heat-flux approach is described for determining the thermal conductivity and conductivity deduced cyclic durability of ceramic thermal and environmental barrier coating systems at very high temperatures (up to 1700 C) under large thermal gradients. The thermal conductivity behavior of advanced thermal and environmental barrier coatings for metallic and Si-based ceramic matrix composite (CMC) component applications has also been investigated using the laser conductivity approach. The relationships between the lattice and radiation conductivities as a function of heat flux and thermal gradient at high temperatures have been examined for the ceramic coating systems. The steady-state laser heat-flux conductivity approach has been demonstrated as a viable means for the development and life prediction of advanced thermal barrier coatings for future turbine engine applications.

  13. Durability and CMAS Resistance of Advanced Environmental Barrier Coatings Systems for SiC/SiC Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming

    2015-01-01

    Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. This paper will emphasize advanced environmental barrier coating developments for SiCSiC turbine airfoil components, by using advanced coating compositions and processing, in conjunction with mechanical and environment testing and durability validations. The coating-CMC degradations and durability in the laboratory simulated engine fatigue-creep and complex operating environments are being addressed. The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will be discussed. The results help understand the advanced EBC-CMC system performance, aiming at the durability improvements of more robust, prime-reliant environmental barrier coatings for successful applications of the component technologies and lifing methodologies.

  14. Design and Performance Optimizations of Advanced Erosion-Resistant Low Conductivity Thermal Barrier Coatings for Rotorcraft Engines

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

    2012-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future rotorcraft engine higher fuel efficiency and lower emission goals. For thermal barrier coatings designed for rotorcraft turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability, because the rotorcraft are often operated in the most severe sand erosive environments. Advanced low thermal conductivity and erosion-resistant thermal barrier coatings are being developed, with the current emphasis being placed on thermal barrier coating toughness improvements using multicomponent alloying and processing optimization approaches. The performance of the advanced thermal barrier coatings has been evaluated in a high temperature erosion burner rig and a laser heat-flux rig to simulate engine erosion and thermal gradient environments. The results have shown that the coating composition and architecture optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic oxidation durability

  15. Selection of commercial hydrolytic enzymes with potential antifouling activity in marine environments.

    PubMed

    Zanaroli, Giulio; Negroni, Andrea; Calisti, Cecilia; Ruzzi, Maurizio; Fava, Fabio

    2011-12-10

    In this work, the marine antifouling potential of some commercially available hydrolytic enzymes acting on the main constituents of extracellular polymeric substances (EPS) involved in bacterial biofilm formation was determined. The selected protease (i.e., alpha-chymotrypsin from bovine pancreas), carbohydrase (i.e., alpha-amylase from porcine pancreas) and lipase (from porcine pancreas) exhibited remarkable hydrolytic activities towards target macromolecules typically composing EPS under a wide range of pHs (6.5-9.0 for alpha-chymotrysin and alpha-amylase; 7.0-8.5 for the lipase) and temperatures (from 10 °C to 30 °C), as well as relevant half-lives (from about 2 weeks to about 2 months), in a marine synthetic water. The activity displayed by each enzyme was poorly affected by the co-presence of the other enzymes, thus indicating their suitability to be employed in combination. None of the enzymes was able to inhibit the formation of biofilm by an actual site marine microbial community when applied singly. However, a mixture of the same enzymes reduced biofilm formation by about 90% without affecting planktonic growth of the same microbial community. This indicates that multiple hydrolytic activities are required to efficiently prevent biofilm formation by complex microbial communities, and that the mixture of enzymes selected in this study has the potential to be employed as an environmental friendly antifouling agent in marine antifouling coatings.

  16. First evaluation of the threat posed by antifouling biocides in the Southern Adriatic Sea.

    PubMed

    Manzo, Sonia; Ansanelli, Giuliana; Parrella, Luisa; Di Landa, Giuseppe; Massanisso, Paolo; Schiavo, Simona; Minopoli, Carmine; Lanza, Bruno; Boggia, Raffaella; Aleksi, Pellumb; Tabaku, Afrim

    2014-08-01

    The CARISMA project (characterization and ecological risk analysis of antifouling biocides in the Southern Adriatic Sea) aims to appraise the quality of the Southern Adriatic Sea between Italy (Apulia region) and Albania and, in particular, the impact due to the use of biocidal antifouling coatings. Under this project, a preliminary survey at the main hot spots of contamination (e.g. ports and marinas) was conducted at the end of the nautical season in 2012. Chemical seawater analyses were complemented with ecotoxicological assays and the results were analyzed by principal component analysis (PCA). As expected, PCA splits the Albanian and Italian ports, according to the different degrees of contamination indicated for the two countries by the experimental data, highlighting the most critical situation in one port of Apulia. In addition, in order to assess the potential adverse ecological effects posed by antifouling agents (i.e. tributyltin (TBT)-irgarol-diuron) on non-target marine organisms, hazard quotients (HQ) were calculated. The results showed a low risk posed by irgarol and diuron whereas the probability of adverse effects was high in the case of TBT.

  17. Does antifouling paint select for antibiotic resistance?

    PubMed

    Flach, Carl-Fredrik; Pal, Chandan; Svensson, Carl Johan; Kristiansson, Erik; Östman, Marcus; Bengtsson-Palme, Johan; Tysklind, Mats; Larsson, D G Joakim

    2017-07-15

    There is concern that heavy metals and biocides contribute to the development of antibiotic resistance via co-selection. Most antifouling paints contain high amounts of such substances, which risks turning painted ship hulls into highly mobile refuges and breeding grounds for antibiotic-resistant bacteria. The objectives of this study were to start investigate if heavy-metal based antifouling paints can pose a risk for co-selection of antibiotic-resistant bacteria and, if so, identify the underlying genetic basis. Plastic panels with one side painted with copper and zinc-containing antifouling paint were submerged in a Swedish marina and biofilms from both sides of the panels were harvested after 2.5-4weeks. DNA was isolated from the biofilms and subjected to metagenomic sequencing. Biofilm bacteria were cultured on marine agar supplemented with tetracycline, gentamicin, copper sulfate or zinc sulfate. Biofilm communities from painted surfaces displayed lower taxonomic diversity and enrichment of Gammaproteobacteria. Bacteria from these communities showed increased resistance to both heavy metals and tetracycline but not to gentamicin. Significantly higher abundance of metal and biocide resistance genes was observed, whereas mobile antibiotic resistance genes were not enriched in these communities. In contrast, we found an enrichment of chromosomal RND efflux system genes, including such with documented ability to confer decreased susceptibility to both antibiotics and biocides/heavy metals. This was paralleled by increased abundances of integron-associated integrase and ISCR transposase genes. The results show that the heavy metal-based antifouling paint exerts a strong selection pressure on marine bacterial communities and can co-select for certain antibiotic-resistant bacteria, likely by favoring species and strains carrying genes that provide cross-resistance. Although this does not indicate an immediate risk for promotion of mobile antibiotic resistance, the

  18. Thermal barrier coatings issues in advanced land-based gas turbines

    SciTech Connect

    Parks, W.P.; Lee, W.Y.; Wright, I.G.

    1995-06-01

    The Department of Energy`s Advanced Turbine Systems (ATS) program is aimed at fostering the development of a new generation of land-based gas turbine systems with overall efficiencies significantly beyond those of current state-of-the-art machines, as well as greatly increased times between inspection and refurbishment, improved environmental impact, and decreased cost. The proposed duty cycle of ATS machines will emphasize different criteria in the selection of materials for the critical components. In particular, thermal barrier coatings (TBCS) will be an essential feature of the hot gas path components in these machines. In fact, the goals of the ATS will require significant improvements in TBC technology, since these turbines will be totally reliant on TBCs, which will be required to function on critical components such as the first stage vanes and blades for times considerably in excess of those experienced in current applications. Issues that assume increased importance are the mechanical and chemical stability of the ceramic layer and of the metallic bond coat; the thermal expansion characteristics and compliance of the ceramic layer; and the thermal conductivity across the thickness of the ceramic layer. Obviously, the ATS program provides a very challenging opportunity for TBCs, and involves some significant opportunities to extend this technology. A significant TBC development effort is planned in the ATS program which will address these key issues.

  19. Calcium-Magnesium-Aluminosilicate (CMAS) Reactions and Degradation Mechanisms of Advanced Environmental Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Ahlborg, Nadia L.; Zhu, Dongming

    2013-01-01

    The thermochemical reactions between calcium-magnesium-aluminosilicate- (CMAS-) based road sand and several advanced turbine engine environmental barrier coating (EBC) materials were studied. The phase stability, reaction kinetics and degradation mechanisms of rare earth (RE)-silicates Yb2SiO5, Y2Si2O7, and RE-oxide doped HfO2 and ZrO2 under the CMAS infiltration condition at 1500 C were investigated, and the microstructure and phase characteristics of CMAS-EBC specimens were examined using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Experimental results showed that the CMAS dissolved RE-silicates to form crystalline, highly non-stoichiometric apatite phases, and in particular attacking the silicate grain boundaries. Cross-section images show that the CMAS reacted with specimens and deeply penetrated into the EBC grain boundaries and formed extensive low-melting eutectic phases, causing grain boundary recession with increasing testing time in the silicate materials. The preliminary results also showed that CMAS reactions also formed low melting grain boundary phases in the higher concentration RE-oxide doped HfO2 systems. The effect of the test temperature on CMAS reactions of the EBC materials will also be discussed. The faster diffusion exhibited by apatite and RE-doped oxide phases and the formation of extensive grain boundary low-melting phases may limit the CMAS resistance of some of the environmental barrier coatings at high temperatures.

  20. Thermal barrier coatings issues in advanced land-based gas turbines

    NASA Technical Reports Server (NTRS)

    Parks, William P.; Hoffman, Eugene E.; Lee, Woo Y.; Wright, Ian G.

    1995-01-01

    The Department of Energy's Advanced Turbine Systems (ATS) program is aimed at fostering the development of a new generation of land-based gas turbine systems with overall efficiencies significantly beyond those of current state-of-the-art machines, as well as greatly increased times between inspection and refurbishment, improved environmental impact, and decreased cost. The proposed duty cycle of ATS machines will emphasize different criteria in the selection of materials for the critical components. In particular, thermal barrier coatings (TBC's) will be an essential feature of the hot gas path components in these machines. In fact, the goals of the ATS will require significant improvements in TBC technology, since these turbines will be totally reliant on TBC's, which will be required to function on critical components such as the first stage vanes and blades for times considerably in excess of those experienced in current applications. Issues that assume increased importance are the mechanical and chemical stability of the ceramic layer and of the metallic bond coat; the thermal expansion characteristics and compliance of the ceramic layer; and the thermal conductivity across the thickness of the ceramic layer. Obviously, the ATS program provides a very challenging opportunity for TBC's, and involves some significant opportunities to extend this technology. A significant TBC development effort is planned in the ATS program which will address these key issues.

  1. Calcium-magnesium Aluminosilicate (CMAS) Interactions with Advanced Environmental Barrier Coating Material

    NASA Technical Reports Server (NTRS)

    Wiesner, Valerie L.; Bansal, Narottam P.

    2015-01-01

    Particulates, like sand and volcanic ash, threaten the development of robust environmental barrier coatings (EBCs) that protect next-generation silicon-based ceramic matrix composite (CMC) turbine engine components from harsh combustion environments during service. The siliceous particulates transform into molten glassy deposits of calcium-magnesium aluminosilicate (CMAS) when ingested by an aircraft engine operating at temperatures above 1200C. In this study, a sample of desert sand was melted into CMAS glass to evaluate high-temperature interactions between the sand glass and an advanced EBC material. Desert sand glass was added to the surface of hot-pressed EBC substrates, which were then heated in air at temperatures ranging from 1200C to 1500C. Scanning electron microscopy and X-ray energy-dispersive spectroscopy were used to evaluate microstructure and phase compositions of specimens and the CMASEBC interface after heat treatments.

  2. Fabrication of transparent antifouling thin films with fractal structure by atmospheric pressure cold plasma deposition.

    PubMed

    Miyagawa, Hayato; Yamauchi, Koji; Kim, Yoon-Kee; Ogawa, Kazufumi; Yamaguchi, Kenzo; Suzaki, Yoshifumi

    2012-12-21

    Antifouling surface with both superhydrophobicity and oil-repellency has been fabricated on glass substrate by forming fractal microstructure(s). The fractal microstructure was constituted by transparent silica particles of 100 nm diameter and transparent zinc-oxide columns grown on silica particles by atmospheric pressure cold plasma deposition. The sample surface was coated with a chemically adsorbed monomolecular layer. We found that one sample has the superhydrophobic ability with a water droplet contact angle of more than 150°, while another sample has a high transmittance of more than 85% in a wavelength range from 400 to 800 nm.

  3. A New Hard Coat on Cover Layer for Cartridge-Free Blu-ray Disc

    NASA Astrophysics Data System (ADS)

    Han, Mi Young; Kang, Tae-Sik; Lee, Seong-Keun; Jang, Sung Hoon; Seo, Hun; Lee, Chang-Ho

    2004-07-01

    A new UV-curable hard coat resin with an excellent antifouling property has been developed. A 3-μm-thick hard coat layer was stacked onto a 97-μm-thick cover layer by spin coating. The characteristics of the hard coat layer, such as pencil hardness, microscratch resistance, adhesion, water contact angle and jitter, have been investigated.

  4. Field results of antifouling techniques for optical instruments

    USGS Publications Warehouse

    Strahle, W.J.; Hotchkiss, F.S.; Martini, M.A.

    1998-01-01

    An anti-fouling technique is developed for the protection of optical instruments from biofouling which leaches a bromide compound into a sample chamber and pumps new water into the chamber prior to measurement. The primary advantage of using bromide is that it is less toxic than the metal-based antifoulants. The drawback of the bromide technique is also discussed.

  5. Blanch Resistant and Thermal Barrier NiAl Coating Systems for Advanced Copper Alloys

    NASA Technical Reports Server (NTRS)

    Raj, Sai V. (Inventor)

    2005-01-01

    A method of forming an environmental resistant thermal barrier coating on a copper alloy is disclosed. The steps include cleansing a surface of a copper alloy, depositing a bond coat on the cleansed surface of the copper alloy, depositing a NiAl top coat on the bond coat and consolidating the bond coat and the NiAl top coat to form the thermal barrier coating. The bond coat may be a nickel layer or a layer composed of at least one of copper and chromium-copper alloy and either the bond coat or the NiAl top coat or both may be deposited using a low pressure or vacuum plasma spray.

  6. Pseudoalteromonas spp. serve as initial bacterial attractants in mesocosms of coastal waters but have subsequent antifouling capacity in mesocosms and when embedded in paint.

    PubMed

    Bernbom, Nete; Ng, Yoke Yin; Olsen, Stefan Møller; Gram, Lone

    2013-11-01

    The purpose of the present study was to determine if the monoculture antifouling effect of several pigmented pseudoalteromonads was retained in in vitro mesocosm systems using natural coastal seawater and when the bacteria were embedded in paint used on surfaces submerged in coastal waters. Pseudoalteromonas piscicida survived on a steel surface and retained antifouling activity for at least 53 days in sterile seawater, whereas P. tunicata survived and had antifouling activity for only 1 week. However, during the first week, all Pseudoalteromonas strains facilitated rather than prevented bacterial attachment when used to coat stainless steel surfaces and submerged in mesocosms with natural seawater. The bacterial density on surfaces coated with sterile growth medium was 10(5) cells/cm(2) after 7 days, whereas counts on surfaces precoated with Pseudoalteromonas were significantly higher, at 10(6) to 10(8) cells/cm(2). However, after 53 days, seven of eight Pseudoalteromonas strains had reduced total bacterial adhesion compared to the control. P. piscicida, P. antarctica, and P. ulvae remained on the surface, at levels similar to those in the initial coating, whereas P. tunicata could not be detected. Larger fouling organisms were observed on all plates precoated with Pseudoalteromonas; however, plates coated only with sterile growth medium were dominated by a bacterial biofilm. Suspensions of a P. piscicida strain and a P. tunicata strain were incorporated into ship paints (Hempasil x3 87500 and Hempasil 77500) used on plates that were placed at the Hempel A/S test site in Jyllinge Harbor. For the first 4 months, no differences were observed between control plates and treated plates, but after 5 to 6 months, the control plates were more fouled than the plates with pseudoalteromonad-based paint. Our study demonstrates that no single laboratory assay can predict antifouling effects and that a combination of laboratory and real-life methods must be used to determine

  7. New hybrid materials based on poly(ethyleneoxide)-grafted polysilazane by hydrosilylation and their anti-fouling activities.

    PubMed

    Nguyen, Thi Dieu Hang; Perrin, François-Xavier; Nguyen, Dinh Lam

    2013-01-01

    The objective of this work was to develop new coating materials based on poly(ethyleneoxide) (PEO), which was grafted onto polysilazane (PSZ) by hydrosilylation. Three types of PEO with different molecular weights (350, 750, 2000 g/mol) were studied. The kinetics and yields of this reaction have been surveyed by (1)H and (13)C NMR spectroscopy. The PEO grafting-density onto PSZ by hydrosilylation increases with a reduction of the S-H/allyl ratio and a decrease of the PEO chain-length. The PEO-graft-PSZ (PSZ-PEO) hybrid coatings, which can be used to prevent the adhesion of marine bacteria on surfaces, were applied by moisture curing at room temperature. The anti-adhesion performance, and thus the anti-fouling activity, of the coatings against three marine bacteria species, Clostridium sp. SR1, Neisseria sp. LC1 and Neisseria sp. SC1, was examined. The anti-fouling activity of the coatings depends on the grafting density and the chain length of PEO. The shortest PEO(350 g/mol)-graft-PSZ with the highest graft density was found to have the best anti-fouling activity. As the density of grafted PEO(750 g/mol) and PEO(2000 g/mol) chains onto the PSZ surface is approximately equal, the relative effectiveness of these two types of PEO is controlled by the length of the PEO chain. The PEO(2000 g/mol)-graft-PSZ coatings are more efficient than the PEO(750 g/mol)-graft-PSZ coatings for the bacterial anti-adhesion.

  8. New hybrid materials based on poly(ethyleneoxide)-grafted polysilazane by hydrosilylation and their anti-fouling activities

    PubMed Central

    Perrin, François-Xavier; Nguyen, Dinh Lam

    2013-01-01

    Summary The objective of this work was to develop new coating materials based on poly(ethyleneoxide) (PEO), which was grafted onto polysilazane (PSZ) by hydrosilylation. Three types of PEO with different molecular weights (350, 750, 2000 g/mol) were studied. The kinetics and yields of this reaction have been surveyed by 1H and 13C NMR spectroscopy. The PEO grafting-density onto PSZ by hydrosilylation increases with a reduction of the S–H/allyl ratio and a decrease of the PEO chain-length. The PEO-graft-PSZ (PSZ-PEO) hybrid coatings, which can be used to prevent the adhesion of marine bacteria on surfaces, were applied by moisture curing at room temperature. The anti-adhesion performance, and thus the anti-fouling activity, of the coatings against three marine bacteria species, Clostridium sp. SR1, Neisseria sp. LC1 and Neisseria sp. SC1, was examined. The anti-fouling activity of the coatings depends on the grafting density and the chain length of PEO. The shortest PEO(350 g/mol)-graft-PSZ with the highest graft density was found to have the best anti-fouling activity. As the density of grafted PEO(750 g/mol) and PEO(2000 g/mol) chains onto the PSZ surface is approximately equal, the relative effectiveness of these two types of PEO is controlled by the length of the PEO chain. The PEO(2000 g/mol)-graft-PSZ coatings are more efficient than the PEO(750 g/mol)-graft-PSZ coatings for the bacterial anti-adhesion. PMID:24205462

  9. Cross-linked polyelectrolyte multilayers for marine antifouling applications.

    PubMed

    Zhu, Xiaoying; Jańczewski, Dominik; Lee, Serina Siew Chen; Teo, Serena Lay-Ming; Vancso, G Julius

    2013-07-10

    A polyionic multilayer film was fabricated by layer-by-layer (LbL) sequential deposition followed by cross-linking under mild conditions on a substrate surface to inhibit marine fouling. A novel polyanion, featuring methyl ester groups for an easy cross-linking was used as a generic solution for stabilization of LbL films in a harsh environment. Covalent cross-linking was confirmed by FTIR and XPS spectroscopy. AFM was used to observe film morphology and its variation because of cross-linking, as well as to measure the thickness of the LbL films. Cross-linking improved the stability of the LbL film when it was immersed in artificial seawater, natural seawater, and in a polar organic solvent (DMSO). No changes in the thickness and topography of the film were observed in these media. The LbL films prevented settlement of Amphibalanus amphitrite barnacle cyprids and reduced adhesion of the benthic diatom Amphora coffeaeformis. Assay results indicated that the cross-linking process did not weaken the antifouling effect of LbL films. The high stability and low degree of fouling make these coatings potentially promising candidates in marine applications.

  10. Development of antifouling surfaces to reduce bacterial attachment

    NASA Astrophysics Data System (ADS)

    Graham, Mary Viola

    Bacteria are exceptionally good at adhering to surfaces and forming complex structures known as biofilms. This process, known as biofouling, can cause problems for infrastructure (eg, clogging and damaging pipes), for the food industry (eg, contamination of processing surfaces and equipment, and for the medical industry (eg, contamination of indwelling medical devices). Accordingly, multiple strategies have been explored to combat biofouling, including chemical modification of surfaces, development of antibiotic coatings, and more recently, the use of engineered surface topography. When designed properly, engineered surface topographies can significantly reduce bacterial surface attachment, ultimately limiting surface colonization. In this work, we hypothesized that the morphology, size, spacing, and surface pre-treatment of topographical features should directly correlate with the size and shape of target organisms, in order to reduce biofouling. Topographical features with size and spacing from 0.25 to 2 mum were fabricated in silicone elastomer and tested against rod shaped bacteria with an average size of 0.5 x 2 mum and spherical bacteria (cocci) ranging from 0.5 - 1 μm in diameter. Antifouling properties of the different topographical features were tested in both static and flow-based assays, and under oxygen plasma-treated (hydrophilic) and untreated (hydrophobic) surface conditions. We found that surface pre-treatment universally affects the ability bacteria to attach to surfaces, while surface topography limits attachment in a manner dependent on the bacterial size/shape and the size/spacing of the topography.

  11. Preparation and characterization of B4C coatings for advanced research light sources

    PubMed Central

    Störmer, Michael; Siewert, Frank; Sinn, Harald

    2016-01-01

    X-ray optical elements are required for beam transport at the current and upcoming free-electron lasers and synchrotron sources. An X-ray mirror is a combination of a substrate and a coating. The demand for large mirrors with single layers consisting of light or heavy elements has increased during the last few decades; surface finishing technology is currently able to process mirror lengths up to 1 m with microroughness at the sub-nanometre level. Additionally, thin-film fabrication is able to deposit a suitable single-layer material, such as boron carbide (B4C), some tens of nanometres thick. After deposition, the mirror should provide excellent X-ray optical properties with respect to coating thickness errors, microroughness values and slope errors; thereby enabling the mirror to transport the X-ray beam with high reflectivity, high beam flux and an undistorted wavefront to an experimental station. At the European XFEL, the technical specifications of the future mirrors are extraordinarily challenging. The acceptable shape error of the mirrors is below 2 nm along the whole length of 1 m. At the Helmholtz-Zentrum Geesthacht (HZG), amorphous layers of boron carbide with thicknesses in the range 30–60 nm were fabricated using the HZG sputtering facility, which is able to cover areas up to 1500 mm long by 120 mm wide in one step using rectangular B4C sputtering targets. The available deposition area is suitable for the specified X-ray mirror dimensions of upcoming advanced research light sources such as the European XFEL. The coatings produced were investigated by means of X-ray reflectometry and interference microscopy. The experimental results for the B4C layers are discussed according to thickness uniformity, density, microroughness and thermal stability. The variation of layer thickness in the tangential and sagittal directions was investigated in order to estimate the achieved level of uniformity over the whole deposition area, which is

  12. Preparation and characterization of B4C coatings for advanced research light sources.

    PubMed

    Störmer, Michael; Siewert, Frank; Sinn, Harald

    2016-01-01

    X-ray optical elements are required for beam transport at the current and upcoming free-electron lasers and synchrotron sources. An X-ray mirror is a combination of a substrate and a coating. The demand for large mirrors with single layers consisting of light or heavy elements has increased during the last few decades; surface finishing technology is currently able to process mirror lengths up to 1 m with microroughness at the sub-nanometre level. Additionally, thin-film fabrication is able to deposit a suitable single-layer material, such as boron carbide (B4C), some tens of nanometres thick. After deposition, the mirror should provide excellent X-ray optical properties with respect to coating thickness errors, microroughness values and slope errors; thereby enabling the mirror to transport the X-ray beam with high reflectivity, high beam flux and an undistorted wavefront to an experimental station. At the European XFEL, the technical specifications of the future mirrors are extraordinarily challenging. The acceptable shape error of the mirrors is below 2 nm along the whole length of 1 m. At the Helmholtz-Zentrum Geesthacht (HZG), amorphous layers of boron carbide with thicknesses in the range 30-60 nm were fabricated using the HZG sputtering facility, which is able to cover areas up to 1500 mm long by 120 mm wide in one step using rectangular B4C sputtering targets. The available deposition area is suitable for the specified X-ray mirror dimensions of upcoming advanced research light sources such as the European XFEL. The coatings produced were investigated by means of X-ray reflectometry and interference microscopy. The experimental results for the B4C layers are discussed according to thickness uniformity, density, microroughness and thermal stability. The variation of layer thickness in the tangential and sagittal directions was investigated in order to estimate the achieved level of uniformity over the whole deposition area, which is considerably

  13. Bioinspired Surface for Low Drag, Self-Cleaning, and Antifouling: Shark Skin, Butterfly and Rice Leaf Effects

    NASA Astrophysics Data System (ADS)

    Bixler, Gregroy D.

    In this thesis, first presented is an overview of inorganic-fouling and biofouling which is generally undesirable for many medical, marine, and industrial applications. A survey of nature's flora and fauna are studied in order to discover new antifouling methods that could be mimicked for engineering applications. New antifouling methods will presumably incorporate a combination of physical and chemical controls. Presented are mechanisms and experimental results focusing on laminar and turbulent drag reducing shark skin inspired riblet surfaces. This includes new laser etched and riblet film samples for closed channel drag using water, oil, and air as well as in wind tunnel. Also presented are mechanisms and experimental results focusing on the newly discovered rice and butterfly wing effect surfaces. Morphology, drag, self-cleaning, contact angle, and contact angle hysteresis data are presented to understand the role of sample geometrical dimensions, wettability, viscosity, and velocity. Hierarchical liquid repellent coatings combining nano- and micro-sized features and particles are utilized to recreate or combine various effects. Such surfaces have been fabricated with photolithography, soft lithography, hot embossing, and coating techniques. Discussion is provided along with new conceptual models describing the role of surface structures related to low drag, self-cleaning, and antifouling properties. Modeling provides design guidance when developing novel low drag and self-cleaning surfaces for medical, marine, and industrial applications.

  14. Advanced thermal barrier coating system development. Technical progress report, January 1, 1996--March 31, 1996

    SciTech Connect

    1996-04-08

    Objectives of this program are to provide a thermal barrier coating system with increased temperature capability and improved reliability relative to current state of the art systems. This report describes the bond coat deposition process, manufacturing, and repair.

  15. Corrosion Testing of Advanced Coatings in Accordance with Hard Chrome Alternatives Team Actuator Joint Test Protocol

    DTIC Science & Technology

    2006-01-24

    Spray (TS) Coatings • Tungsten Carbide alloys • Chromium Carbide alloys • Proprietary TS coatings • Electrospark deposition • EHC Enhancement...Environmental, safety, and health concerns regarding potential exposure to hexavalent chromium during EHC deposition process • Regulatory

  16. Advances in Concentrating Solar Power Collectors: Mirrors and Solar Selective Coatings

    SciTech Connect

    Kenendy, C. E.

    2007-10-10

    The intention is to explore the feasibility of depositing the coating by lower-cost methods and to perform a rigorous cost analysis after a viable high-temperature solar-selective coating is demonstrated by e-beam.

  17. Advanced polymer-inorganic hybrid hard coatings utilizing in situ polymerization method.

    PubMed

    Takaki, Toshihiko; Nishiura, Katsunori; Mizuta, Yasushi; Itou, Yuichi

    2006-12-01

    Hard coatings are frequently used to give plastics high scratch resistance. Coating hardness and adhesion to the substrate are considered to be key factors influencing scratch resistance, but it is difficult to produce coatings that have both properties. Hybridization of polymers and inorganic materials is a promising approach for solving this problem. We prepared polymer-silica hybrid coatings by using in situ polymerization to carry out radical polymerization of vinyl monomers in a sol-gel solution of alkoxysilanes, and measured the abrasion resistance of the coatings. However, the expected properties were not obtained because the sol-gel reaction did not perfectly proceed on the surface of the coatings under the N2 conditions. We found that curing the hybrid coatings by UV irradiation in air promoted the sol-gel reaction on the surface, resulting in coatings having excellent abrasion resistance.

  18. Advanced High Temperature Coating Systems Beyond Current State of the Art Systems.

    DTIC Science & Technology

    1986-04-15

    and diffusion aluminide coatings . The approach which was used .. consisted of attempting to obtain reaction product barriers with improved protective...Bauer(9 9 ). Most of the work in this area has involved silicide coatings on refractory metals and superalloys in which the coatings are formed by Si...3, 1976, pp. 163-187. 20. T. E. Strangman, Thermal Fatique of Oxidation Resistant Overlay Coatings for Superalloys , PhD Disseration, University of

  19. The role of nano-roughness in antifouling

    SciTech Connect

    Scardino, A.J.; Zhang, H.; Cookson, D.J.; Lamb, R.N.; de Nys, R.

    2010-02-19

    Nano-engineered superhydrophobic surfaces have been investigated for potential fouling resistance properties. Integrating hydrophobic materials with nanoscale roughness generates surfaces with superhydrophobicity that have water contact angles ({theta}) >150{sup o} and concomitant low hysteresis (<10{sup o}). Three superhydrophobic coatings (SHCs) differing in their chemical composition and architecture were tested against major fouling species (Amphora sp., Ulva rigida, Polysiphonia sphaerocarpa, Bugula neritina, Amphibalanus amphitrite) in settlement assays. The SHC which had nanoscale roughness alone (SHC 3) deterred the settlement of all the tested fouling organisms, compared to selective settlement on the SHCs with nano- and micro-scale architectures. The presence of air incursions or nanobubbles at the interface of the SHCs when immersed was characterized using small angle X-ray scattering, a technique sensitive to local changes in electron density contrast resulting from partial or complete wetting of a rough interface. The coating with broad spectrum antifouling properties (SHC 3) had a noticeably larger amount of unwetted interface when immersed, likely due to the comparatively high work of adhesion (60.77 mJ m{sup -2} for SHC 3 compared to 5.78 mJ m-2 for the other two SHCs) required for creating solid/liquid interface from the solid/vapour interface. This is the first example of a non-toxic, fouling resistant surface against a broad spectrum of fouling organisms ranging from plant cells and non-motile spores, to complex invertebrate larvae with highly selective sensory mechanisms. The only physical property differentiating the immersed surfaces is the nano-architectured roughness which supports longer standing air incursions providing a novel non-toxic broad spectrum mechanism for the prevention of biofouling.

  20. Searching for "environmentally-benign" antifouling biocides.

    PubMed

    Cui, Yan Ting; Teo, Serena L M; Leong, Wai; Chai, Christina L L

    2014-05-26

    As the result of the ecological impacts from the use of tributyltins (TBT) in shipping, environmental legislation for the registration of chemicals for use in the environment has grown to a monumental challenge requiring product dossiers to include information on the environmental fate and behavior of any chemicals. Specifically, persistence, bioaccumulation and toxicity, collectively known as PBT, are properties of concern in the assessment of chemicals. However, existing measurements of PBT properties are a cumbersome and expensive process, and thus not applied in the early stages of the product discovery and development. Inexpensive methods for preliminary PBT screening would minimize risks arising with the subsequent registration of products. In this article, we evaluated the PBT properties of compounds reported to possess anti-fouling properties using QSAR (quantitative structure-activity relationship) prediction programs such as BIOWIN™ (a biodegradation probability program), KOWWIN™ (log octanol-water partition coefficient calculation program) and ECOSAR™ (Ecological Structure Activity Relationship Programme). The analyses identified some small (Mr < 400) synthetic and natural products as potential candidates for environmentally benign biocides. We aim to demonstrate that while these methods of estimation have limitations, when applied with discretion, they are powerful tools useful in the early stages of research for compound selection for further development as anti-foulants.

  1. Bio-Inspired Design and Fabrication of Micro/Nano-Brush Dual Structural Surfaces for Switchable Oil Adhesion and Antifouling.

    PubMed

    Du, Tao; Ma, Shuanhong; Pei, Xiaowei; Wang, Shutao; Zhou, Feng

    2017-01-01

    The underwater superoleophobic surfaces play a significant role in anti-oil contamination, marine antifouling, etc. Inspired by the Gecko's feet and its self-cleaning property, a hierarchical structure composed of poly (acrylic acid) gel micro-brushes is designed by the liquid-infused method. This surface exhibits underwater superoleophobicity with very low oil adhesion. It is then modified with stimuli-responsive polymer nano-brushes via surface-initiated atom transfer radical polymerization from the embedded initiator. The micro/nano-brush dual structural surfaces can switch the underwater oil adhesion between low and high while keeping the superoleophobicity. The antifouling properties against algae attachment under different mediums are also investigated to show a strong link between oleophobicity and antibiofouling property. The model surface will be very useful in directing the design of marine self-cleaning coatings to both living and non-living species.

  2. Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: Recent Advances and Future Directions

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming

    2016-01-01

    This presentation briefly reviews the SiC/SiC major environmental and environment-fatigue degradations encountered in simulated turbine combustion environments, and thus NASA environmental barrier coating system evolution for protecting the SiC/SiC Ceramic Matrix Composites for meeting the engine performance requirements. The presentation will review several generations of NASA EBC materials systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. This paper will also focus on the performance requirements and design considerations of environmental barrier coatings for next generation turbine engine applications. The current development emphasis is placed on advanced NASA candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. The efforts have been also directed to developing prime-reliant, self-healing 2700F EBC bond coat; and high stability, lower thermal conductivity, and durable EBC top coats. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance will be described. The research and development opportunities for turbine engine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be briefly discussed.

  3. Fireside Corrosion Behavior of HVOF and Plasma-Sprayed Coatings in Advanced Coal/Biomass Co-Fired Power Plants

    NASA Astrophysics Data System (ADS)

    Hussain, T.; Dudziak, T.; Simms, N. J.; Nicholls, J. R.

    2013-06-01

    This article presents a systematic evaluation of coatings for advanced fossil fuel plants and addresses fireside corrosion in coal/biomass-derived flue gases. A selection of four candidate coatings: alloy 625, NiCr, FeCrAl and NiCrAlY were deposited onto superheaters/reheaters alloy (T91) using high-velocity oxy-fuel (HVOF) and plasma spraying. A series of laboratory-based fireside corrosion exposures were carried out on these coated samples in furnaces under controlled atmosphere for 1000 h at 650 °C. The tests were carried out using the "deposit-recoat" test method to simulate the environment that was anticipated from air-firing 20 wt.% cereal co-product mixed with a UK coal. The exposures were carried out using a deposit containing Na2SO4, K2SO4, and Fe2O3 to produce alkali-iron tri-sulfates, which had been identified as the principal cause of fireside corrosion on superheaters/reheaters in pulverized coal-fired power plants. The exposed samples were examined in an ESEM with EDX analysis to characterize the damage. Pre- and post-exposure dimensional metrologies were used to quantify the metal damage in terms of metal loss distributions. The thermally sprayed coatings suffered significant corrosion attack from a combination of aggressive combustion gases and deposit mixtures. In this study, all the four plasma-sprayed coatings studied performed better than the HVOF-sprayed coatings because of a lower level of porosity. NiCr was found to be the best performing coating material with a median metal loss of ~87 μm (HVOF sprayed) and ~13 μm (plasma sprayed). In general, the median metal damage for coatings had the following ranking (in the descending order: most to the least damage): NiCrAlY > alloy 625 > FeCrAl > NiCr.

  4. Antifouling and antimicrobial polymer membranes based on bioinspired polydopamine and strong hydrogen-bonded poly(N-vinyl pyrrolidone).

    PubMed

    Jiang, Jinhong; Zhu, Liping; Zhu, Lijing; Zhang, Hongtao; Zhu, Baoku; Xu, Youyi

    2013-12-26

    A facile and versatile approach for the preparation of antifouling and antimicrobial polymer membranes has been developed on the basis of bioinspired polydopamine (PDA) in this work. It is well-known that a tightly adherent PDA layer can be generated over a wide range of material surfaces through a simple dip-coating process in dopamine aqueous solution. The resulting PDA coating is prone to be further surface-tailored and functionalized via secondary treatments because of its robust reactivity. Herein, a typical hydrophobic polypropylene (PP) porous membrane was first coated with a PDA layer and then further modified by poly(N-vinyl pyrrolidone) (PVP) via multiple hydrogen-bonding interactions between PVP and PDA. Data of water contact angle measurements showed that hydrophilicity and wettability of the membranes were significantly improved after introducing PDA and PVP layers. Both permeation fluxes and antifouling properties of the modified membranes were enhanced as evaluated in oil/water emulsion filtration, protein filtration, and adsorption tests. Furthermore, the modified membranes showed remarkable antimicrobial activity after iodine complexation with the PVP layer. The PVP layer immobilized on the membrane had satisfying long-term stability and durability because of the strong noncovalent forces between PVP and PDA coating. The strategy of material surface modification reported here is substrate-independent, and applicable to a broad range of materials and geometries, which allows effective development of materials with novel functional coatings based on the mussel-inspired surface chemistry.

  5. Advances in multi-spectral Diamond-Like Carbon (DLC) coatings

    NASA Astrophysics Data System (ADS)

    Keck, Jason; Karp, Christopher

    2014-05-01

    We discuss the development and applications of a new approach to Diamond-Like Carbon (DLC) coating that provides the durability of traditional DLC coatings, with the addition of significantly more transmission at visible wavelengths and greater transmission in the IR. We developed a deposition system design that incorporates multiple coating technologies, allowing for multiple material design approaches. This has enabled the manufacture of DLC coatings with improved extended spectral properties, suitable for applications in which the coating must withstand airborne particulate impacts, corrosive fluids, environmental extremes, and abrasive physical handling, while offering better than typical transmission in the visible or infrared wavelength regions, or both.

  6. Fission Product Monitoring of TRISO Coated Fuel For The Advanced Gas Reactor -1 Experiment

    SciTech Connect

    Dawn M. Scates; John K. Hartwell; John b. Walter

    2010-10-01

    The US Department of Energy has embarked on a series of tests of TRISO-coated particle reactor fuel intended for use in the Very High Temperature Reactor (VHTR) as part of the Advanced Gas Reactor (AGR) program. The AGR-1 TRISO fuel experiment, currently underway, is the first in a series of eight fuel tests planned for irradiation in the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL). The AGR-1 experiment reached a peak compact averaged burn up of 9% FIMA with no known TRISO fuel particle failures in March 2008. The burnup goal for the majority of the fuel compacts is to have a compact averaged burnup greater than 18% FIMA and a minimum compact averaged burnup of 14% FIMA. At the INL the TRISO fuel in the AGR-1 experiment is closely monitored while it is being irradiated in the ATR. The effluent monitoring system used for the AGR-1 fuel is the Fission Product Monitoring System (FPMS). The FPMS is a valuable tool that provides near real-time data indicative of the AGR-1 test fuel performance and incorporates both high-purity germanium (HPGe) gamma-ray spectrometers and sodium iodide [NaI(Tl)] scintillation detector-based gross radiation monitors. To quantify the fuel performance, release-to-birth ratios (R/B’s) of radioactive fission gases are computed. The gamma-ray spectra acquired by the AGR-1 FPMS are analyzed and used to determine the released activities of specific fission gases, while a dedicated detector provides near-real time count rate information. Isotopic build up and depletion calculations provide the associated isotopic birth rates. This paper highlights the features of the FPMS, encompassing the equipment, methods and measures that enable the calculation of the release-to-birth ratios. Some preliminary results from the AGR-1 experiment are also presented.

  7. Fission Product Monitoring of TRISO Coated Fuel For The Advanced Gas Reactor -1 Experiment

    SciTech Connect

    Dawn M. Scates; John K Hartwell; John B. Walter

    2008-09-01

    The US Department of Energy has embarked on a series of tests of TRISO-coated particle reactor fuel intended for use in the Very High Temperature Reactor (VHTR) as part of the Advanced Gas Reactor (AGR) program. The AGR-1 TRISO fuel experiment, currently underway, is the first in a series of eight fuel tests planned for irradiation in the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL). The AGR-1 experiment reached a peak compact averaged burn up of 9% FIMA with no known TRISO fuel particle failures in March 2008. The burnup goal for the majority of the fuel compacts is to have a compact averaged burnup greater than 18% FIMA and a minimum compact averaged burnup of 14% FIMA. At the INL the TRISO fuel in the AGR-1 experiment is closely monitored while it is being irradiated in the ATR. The effluent monitoring system used for the AGR-1 fuel is the Fission Product Monitoring System (FPMS). The FPMS is a valuable tool that provides near real-time data indicative of the AGR-1 test fuel performance and incorporates both high-purity germanium (HPGe) gamma-ray spectrometers and sodium iodide [NaI(Tl)] scintillation detector-based gross radiation monitors. To quantify the fuel performance, release-to-birth ratios (R/B’s) of radioactive fission gases are computed. The gamma-ray spectra acquired by the AGR-1 FPMS are analyzed and used to determine the released activities of specific fission gases, while a dedicated detector provides near-real time count rate information. Isotopic build up and depletion calculations provide the associated isotopic birth rates. This paper highlights the features of the FPMS, encompassing the equipment, methods and measures that enable the calculation of the release-to-birth ratios. Some preliminary results from the AGR-1 experiment are also presented.

  8. Ultrathin coatings of nanoporous materials as property enhancements for advanced functional materials.

    SciTech Connect

    Coker, Eric Nicholas

    2010-11-01

    This report summarizes the findings of a five-month LDRD project funded through Sandia's NTM Investment Area. The project was aimed at providing the foundation for the development of advanced functional materials through the application of ultrathin coatings of microporous or mesoporous materials onto the surface of substrates such as silicon wafers. Prior art teaches that layers of microporous materials such as zeolites may be applied as, e.g., sensor platforms or gas separation membranes. These layers, however, are typically several microns to several hundred microns thick. For many potential applications, vast improvements in the response of a device could be realized if the thickness of the porous layer were reduced to tens of nanometers. However, a basic understanding of how to synthesize or fabricate such ultra-thin layers is lacking. This report describes traditional and novel approaches to the growth of layers of microporous materials on silicon wafers. The novel approaches include reduction of the quantity of nutrients available to grow the zeolite layer through minimization of solution volume, and reaction of organic base (template) with thermally-oxidized silicon wafers under a steam atmosphere to generate ultra-thin layers of zeolite MFI.

  9. Advances in Surface Plasmon Resonance Imaging enable quantitative measurement of laterally heterogeneous coatings of nanoscale thickness

    NASA Astrophysics Data System (ADS)

    Raegen, Adam; Reiter, Kyle; Clarke, Anthony; Lipkowski, Jacek; Dutcher, John

    2013-03-01

    The Surface Plasmon Resonance (SPR) phenomenon is routinely exploited to qualitatively probe changes to the optical properties of nanoscale coatings on thin metallic surfaces, for use in probes and sensors. Unfortunately, extracting truly quantitative information is usually limited to a select few cases - uniform absorption/desorption of small biomolecules and films, in which a continuous ``slab'' model is a good approximation. We present advancements in the SPR technique that expand the number of cases for which the technique can provide meaningful results. Use of a custom, angle-scanning SPR imaging system, together with a refined data analysis method, allow for quantitative kinetic measurements of laterally heterogeneous systems. We first demonstrate the directionally heterogeneous nature of the SPR phenomenon using a directionally ordered sample, then show how this allows for the calculation of the average coverage of a heterogeneous sample. Finally, the degradation of cellulose microfibrils and bundles of microfibrils due to the action of cellulolytic enzymes will be presented as an excellent example of the capabilities of the SPR imaging system.

  10. Chitosan-zinc oxide nanocomposite coatings for the prevention of marine biofouling.

    PubMed

    Al-Naamani, Laila; Dobretsov, Sergey; Dutta, Joydeep; Burgess, J Grant

    2017-02-01

    Marine biofouling is a worldwide problem affecting maritime industries. Global concerns about the high toxicity of antifouling paints have highlighted the need to develop less toxic antifouling coatings. Chitosan is a natural polymer with antimicrobial, antifungal and antialgal properties that is obtained from partial deacetylation of crustacean waste. In the present study, nanocomposite chitosan-zinc oxide (chitosan-ZnO) nanoparticle hybrid coatings were developed and their antifouling activity was tested. Chitosan-ZnO nanoparticle coatings showed anti-diatom activity against Navicula sp. and antibacterial activity against the marine bacterium Pseudoalteromonas nigrifaciens. Additional antifouling properties of the coatings were investigated in a mesocosm study using tanks containing natural sea water under controlled laboratory conditions. Each week for four weeks, biofilm was removed and analysed by flow cytometry to estimate total bacterial densities on the coated substrates. Chitosan-ZnO hybrid coatings led to better inhibition of bacterial growth in comparison to chitosan coatings alone, as determined by flow cytometry. This study demonstrates the antifouling potential of chitosan-ZnO nanocomposite hybrid coatings, which can be used for the prevention of biofouling.

  11. Materials for Advanced Turbine Engines (MATE). Project 4: Erosion resistant compressor airfoil coating

    NASA Technical Reports Server (NTRS)

    Rashid, J. M.; Freling, M.; Friedrich, L. A.

    1987-01-01

    The ability of coatings to provide at least a 2X improvement in particulate erosion resistance for steel, nickel and titanium compressor airfoils was identified and demonstrated. Coating materials evaluated included plasma sprayed cobalt tungsten carbide, nickel carbide and diffusion applied chromium plus boron. Several processing parameters for plasma spray processing and diffusion coating were evaluated to identify coating systems having the most potential for providing airfoil erosion resistance. Based on laboratory results and analytical evaluations, selected coating systems were applied to gas turbine blades and evaluated for surface finish, burner rig erosion resistance and effect on high cycle fatigue strength. Based on these tests, the following coatings were recommended for engine testing: Gator-Gard plasma spray 88WC-12Co on titanium alloy airfoils, plasma spray 83WC-17Co on steel and nickel alloy airfoils, and Cr+B on nickel alloy airfoils.

  12. Probing structure-antifouling activity relationships of polyacrylamides and polyacrylates.

    PubMed

    Zhao, Chao; Zhao, Jun; Li, Xiaosi; Wu, Jiang; Chen, Shenfu; Chen, Qiang; Wang, Qiuming; Gong, Xiong; Li, Lingyan; Zheng, Jie

    2013-07-01

    We have synthesized two different polyacrylamide polymers with amide groups (polySBAA and polyHEAA) and two corresponding polyacrylate polymers without amide groups (polySBMA and polyHEA), with particular attention to the evaluation of the effect of amide group on the hydration and antifouling ability of these systems using both computational and experimental approaches. The influence of polymer architectures of brushes, hydrogels, and nanogels, prepared by different polymerization methods, on antifouling performance is also studied. SPR and ELISA data reveal that all polymers exhibit excellent antifouling ability to repel proteins from undiluted human blood serum/plasma, and such antifouling ability can be further enhanced by presenting amide groups in polySBAA and polyHEAA as compared to polySBMA and polyHEA. The antifouling performance is positively correlated with the hydration properties. Simulations confirm that four polymers indeed have different hydration characteristics, while all presenting a strong hydration overall. Integration of amide group with pendant hydroxyl or sulfobetaine group in polymer backbones is found to increase their surface hydration of polymer chains and thus to improve their antifouling ability. Importantly, we present a proof-of-concept experiment to synthesize polySBAA nanogels, which show a switchable property between antifouling and pH-responsive functions driven by acid-base conditions, while still maintaining high stability in undiluted fetal bovine serum and minimal toxicity to cultured cells. This work provides important structural insights into how very subtle structural changes in polymers can yield great improvement in biological activity, specifically the inclusion of amide group in polymer backbone/sidechain enables to obtain antifouling materials with better performance for biomedical applications.

  13. [Research advances on controlled-release mechanisms of nutrients in coated fertilizers].

    PubMed

    Zhang, Haijun; Wu, Zhijie; Liang, Wenju; Xie, Hongtu

    2003-12-01

    Using encapsulation techniques to coat easily soluble fertilizers is an important way to improve fertilizer use efficiency while reduce environmental hazards. Based on a wide range of literature collection on coated fertilizer research, the theories, processes, and characters of nutrient controlled-release from coated fertilizer were discussed, and the factors affecting nutrient controlled-release and the mathematical simulations on it were reviewed. The main tendencies related to this research in China were also put forward.

  14. Advances in supercritical fluid spray application of low-pollution coatings

    SciTech Connect

    Nielsen, K.A.; Dickson, D.J.; Derderian, E.J.; Glancy, C.W.; Goad, J.D.

    1991-12-31

    The volatile organic compound (VOC) content of coating formulations, which causes ozone formation in the environment, has now been reduced up to 80% by using supercritical carbon dioxide to replace volatile organic solvents in conventional coating formulations. Toxic solvents classified as hazardous air pollutants by the Clean Air Act can be totally eliminated. The concept can also be applied to high-solids coatings (1) to further reduce VOC emissions and (2) to improve coating performance by using higher molecular weight polymers. Commercial fluid delivery equipment and spray guns are now available. The technology is being demonstrated on industrial spray lines.

  15. Ultrasonic Mastering of Filter Flow and Antifouling of Renewable Resources.

    PubMed

    Radziuk, Darya; Möhwald, Helmuth

    2016-04-04

    Inadequate access to pure water and sanitation requires new cost-effective, ergonomic methods with less consumption of energy and chemicals, leaving the environment cleaner and sustainable. Among such methods, ultrasound is a unique means to control the physics and chemistry of complex fluids (wastewater) with excellent performance regarding mass transfer, cleaning, and disinfection. In membrane filtration processes, it overcomes diffusion limits and can accelerate the fluid flow towards the filter preventing antifouling. Here, we outline the current state of knowledge and technological design, with a focus on physicochemical strategies of ultrasound for water cleaning. We highlight important parameters of ultrasound for the delivery of a fluid flow from a technical perspective employing principles of physics and chemistry. By introducing various ultrasonic methods, involving bubbles or cavitation in combination with external fields, we show advancements in flow acceleration and mass transportation to the filter. In most cases we emphasize the main role of streaming and the impact of cavitation with a perspective to prevent and remove fouling deposits during the flow. We also elaborate on the deficiencies of present technologies and on problems to be solved to achieve a wide-spread application.

  16. New advances in the 3D characterization of mineral coating layers on paper.

    PubMed

    Chinga-Carrasco, G; Kauko, H; Myllys, M; Timonen, J; Wang, B; Zhou, M; Fossum, J O

    2008-11-01

    The surface characteristics of a large set of commercial lightweight coated paper grades are explored. The quantification of the 3D structure is revealed by atomic force microscopy, laser profilometry and X-ray microtomography. This comprehensive study demonstrates the suitability of different and modern methods for assessing critical coating layer properties, thus identifying the right tools for specific structural analyses. Based on the assessment of the top and bottom surfaces of 25 commercial lightweight coated samples, three main conclusions can be drawn: (1) the facet orientation polar angle is a function of roughness, (2) skewness did not describe the surface details affecting the gloss of the commercial lightweight coated samples assessed in this study and (3) surface roughness at wavelengths below approximately 1.0 microm does not affect the paper gloss significantly. This is important knowledge for the understanding of lightweight coated paper surface structure and its properties.

  17. Effects of a candidate antifouling compound (medetomidine) on pheromone induced mate search in the amphipod Corophium volutator.

    PubMed

    Krång, Anna-Sara; Dahlström, Mia

    2006-12-01

    Environmental hazards associated with traditional, toxic antifouling coatings based on heavy metals calls for the development of alternative, environmentally acceptable antifouling compounds. Medetomidine ((+/-)-4-[1-(2,3-dimethylphenyl)ethyl]-1H-imidazole) is a candidate antifouling biocide which impedes settlement of barnacles in the nanomolar range. Prior to introducing novel biocides it is of great importance to consider potential effects on non-target organisms. This study is the first to investigate the effects of medetomidine on the amphipod Corophium volutator, specifically effects on male mate search behaviour. In a laboratory, Y-maze bioassay, C. volutator males were allowed to follow female pheromones after 24 h exposure to 0 (control), 0.01 and 0.1 microg mL(-1) medetomidine. We found that exposure to medetomidine at both concentrations significantly reduced pheromone induced mate search (by 42-71%), with fewer males crawling towards female odour. The results obtained indicate that medetomidine may impair the reproductive fitness of non-target crustaceans, an aspect that needs to be considered before further commercialisation.

  18. Antifouling properties of poly(methyl methacrylate) films grafted with poly(ethylene glycol) monoacrylate immersed in seawater.

    PubMed

    Iguerb, O; Poleunis, C; Mazéas, F; Compère, C; Bertrand, P

    2008-11-04

    Biofouling of all structures immersed in seawater constitutes an important problem, and many strategies are currently being developed to tackle it. In this context, our previous work shows that poly(ethylene glycol) monoacrylate (PEGA) macromonomer grafted on preoxidized poly(methyl methacrylate) (PMMAox) films exhibits an excellent repellency against the bovine serum albumin used as a model protein. This study aims to evaluate the following: (1) the prevention of a marine extract material adsorption by the modified surfaces and (2) the antifouling property of the PEGA-g-PMMAox substrates when immersed in natural seawater during two seasons (season 1: end of April-beginning of May 2007, and season 2: end of October-beginning of November 2007). The antifouling performances of the PEGA-g-PMMAox films are investigated for different PEG chain lengths and macromonomer concentrations into the PEGA-based coatings. These two parameters are followed as a function of the immersion time, which evolves up to 14 days. The influence of the PEGA layer on marine compounds (proteins and phospholipids) adsorption is evidenced by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). It was found that the antifouling efficiency of the PEGA-grafted surfaces increases with both PEGA concentration and PEG chain length.

  19. Sol-gel broadband antireflective coatings for advanced laser-glass amplifiers

    NASA Astrophysics Data System (ADS)

    Floch, Herve G.; Belleville, Philippe F.; Pegon, Philippe M.

    1994-10-01

    The cost of a large laser system is a strong function of the overall electrical to final photon efficiency. To improve the stored energy and therefore the pumping efficiency of sophisticated and costly laser-glass amplifiers, we have developed a novel two-layer broadband antireflective coating for the blast-shield component. The blast-shield is an optic placed between the flashlamps and the laser disk amplifiers to prevent damage of laser disks by possible explosion of a flashlamp. The sol-gel antireflective coating was dip-coated at room temperature onto 8-cm diameter glass samples. The coating basically consisted of a halfwave- thick high-index material such as ZrO2-PVP (PolyVinyl Pyrrolidone) and a quarterwave- thick low-index material such as SiO2-siloxane. To improve the abrasion resistance of the coated part, a lubricating and water-repellent material was applied as a very thin overcoat. In addition to a 6.5 to 7.2% transmission gain over the spectrum of interest, the coating was moderately abrasion resistant and chemically durable. Flashlamp-induced damage to the antireflective coating for 1000 glow discharges at 10 to 12 J/cm2 were minimal and similar to uncoated parts.

  20. Application of advanced methods for durability assessment of new absorber coatings

    NASA Astrophysics Data System (ADS)

    Frei, Ulrich; Brunold, Stefan; Koehl, Michael; Brucker, Franz; Carlsson, Bo; Moeller, K.

    1995-08-01

    Accelerated life testing of solar energy materials has been one of the main topics within the former Task X 'Solar Materials Research and Development' of the International Energy Agency (IEA) Solar Heating and Cooling Programme. In the case study of some selective solar absorber coating materials for domestic hot water systems procedures are presented for service time assessment, applicable for example to absorber coating materials. As a continuation of the finalized Task X a working group, 'Materials in Solar Thermal Systems' also in the framework of the International Energy Agency (IEA) 'Solar Heating and Cooling Programme' was initiated. One of the first projects is described here. Its aim is to investigate the conformity of the durability assessment, applied on solar absorber coatings tested by different laboratories. Each lab is working independently, this means there is no information exchange between the labs until the results are on paper. Test samples are delivered by the participants. Four different absorber coatings are identified to be useful for the project. The coating materials as well as the production procedures of the coatings are not relevant for the study, therefore no information is given. The experimental procedures as well as the judgement over the different absorber coatings are described in detail. Some comparisons between individual results of the different labs indicates possible weaknesses and further necessary refinements. Finally, expected costs for the whole procedure are presented.

  1. Dendritic saccharide surfactant polymers as antifouling interface materials to reduce platelet adhesion.

    PubMed

    Zhu, Junmin; Marchant, Roger E

    2006-04-01

    Here, we report on the synthesis of dendritic saccharide surfactant polymers as antifouling interface materials to reduce platelet adhesion. An acetal-protected poly(amidoamine) (PAMAM) dendron (5, G = 2) was first synthesized by using aminoacetaldehyde dimethyl acetal (1) as the starting material to provide a monovalent focal structure with dimethyl acetal-protected aldehyde functionality. Maltose dendron (M4, 6) was obtained by reacting the peripheral amine groups of acetal-dendron (5) with maltonolactone. The dendritic surfactant polymers (9) were then synthesized via a two-step method by sequential addition of maltose dendron and hexanal to react with the amine groups on the poly(vinylamine) (PVAm) backbone. Surface activity of the amphiphilic glycopolymers at the air/water interface was demonstrated by reduction in water surface tension. Adsorption of the amphiphilic glycopolymers at the solid/water interface was examined on octadecyltrichlorosilane (OTS)-coated coverslips by water contact angle measurements. A nanoscale understanding of surface-induced self-assembly of the dendritic surfactant polymer on highly oriented pyrolytic graphite (HOPG) was gained using AFM operated in fluid tapping mode. A lateral ordering of adsorbing surfactant polymer was visualized with a pattern in strands 60 degrees out of alignment. The static platelet adhesion tests show that the hexyl side chains can facilitate adsorption of the surfactant polymers onto hydrophobic substrates, while the maltose dendron side chains can provide a dense canopy of protective glycocalyx-like layer as an antifouling interface to reduce platelet adhesion.

  2. Recent advances in short-wavelength AR coatings for thinned CCDs

    NASA Astrophysics Data System (ADS)

    Blouke, Morley; Nelson, Michael D.; Serra, M.; Knoesen, Andre; Higgins, B.; Delamere, W. Alan; Womack, Gary L.; Flores, James S.; Duncan, T. M.; Reed, R.

    1992-08-01

    This paper discusses the development of two materials as AR coatings for thinned backilluminated charge-coupled devices. The first material is the heavy metal oxide Ta205 deposited as a spin on layer using sol-gel technology. The second material is Si3N4. Both these films have the high index of refraction and low absorption coefficients needed to produce good AR coatings in the near UV down to 300 nm. The goal of the program was to produce a coating which would yield devices with quantum efficiencies of greater than 50 at 300 nm. Both these materials satisfy this goal. Data on test devices will be reported. . 1.

  3. In situ assembly of antifouling/bacterial silver nanoparticle-hydrogel composites with controlled particle release and matrix softening.

    PubMed

    Baek, Kwanghyun; Liang, Jing; Lim, Wan Ting; Zhao, Huimin; Kim, Dong Hyun; Kong, Hyunjoon

    2015-07-22

    Controlling bacterial contamination has been a major challenge for protecting human health and welfare. In this context, hydrogels loaded with silver nanoparticles have been used to prevent biofilm formation on substrates of interest. However, such gel composites are often plagued by rapid loss of silver nanoparticles and matrix softening, and thus the gel becomes less effective for antifouling. To this end, this study demonstrates that in situ photoreaction of an aqueous mixture of silver nitrates, poly(ethylene glycol) diacrylate, and vinylpyrrolidone results in a silver nanoparticle-laden hydrogel composite with minimal nanoparticle loss and matrix softening due to enhanced binding between nanoparticles and the gel. The resulting gel composite successfully inhibits the bacterial growth in media and the bacterial adhesion to surfaces of interest. We suggest that the results of this study serve to advance quality of materials with antifouling/bacterial activities.

  4. Advanced thermal barrier coating system development. Technical progress report, April 1, 1996--May 31, 1996

    SciTech Connect

    1996-06-10

    Objectives of this program are to provide an improved thermal barrier system with increased temperature capability and reliability relative to current systems. This report describes the bond coat development and deposition, manufacturing, and repair.

  5. Controlling cell-material interactions using coatings with advanced polymer architectures

    NASA Astrophysics Data System (ADS)

    Koegler, Peter; Pasic, Paul; Johnson, Graham; Bean, Penny; Lorenz, Guenter; Meagher, Laurence; Thissen, Helmut

    2011-12-01

    Polymeric coatings which allow the effective control of biointerfacial interactions and cellular responses are of increasing interest in a range of biomedical applications in vitro and in vivo such as cell culture tools, biosensors and implantable medical devices. A variety of coating strategies have been developed to gain control over cell-surface interactions but many of them are limited with respect to their function and transferability between different substrate materials. Here, our aim was to establish an easily transferable coating that reduces non-specific cell-surface interactions to a minimum while at the same time presenting functional groups which allow for the subsequent immobilisation of bioactive signals. To achieve this, we have applied an allylamine plasma polymer coating followed by the covalent immobilisation of a macro-initiator providing iniferter functional groups. Subsequent controlled free radical graft polymerisation using the monomers acrylamide and acrylic acid in different molar ratios resulted in highly uniform polymer coatings. Non-specific cell attachment was significantly reduced on coatings representing molar ratios of less than 10% acylic acid. At the same time, we have demonstrated the suitability of these coatings for the subsequent covalent binding of bioactive compounds carrying amine functional groups using the label 2,2,2-trifluoroethylamine. Successful surface modifications were confirmed by X-ray photoelectron spectroscopy (XPS) and profilometry. The cellular response was evaluated using HeLa cell attachment experiments for up to 24 hours. We expect that the coating platform established in this study will be translated into a number of biomedical applications, including applications in implantable devices and regenerative medicine.

  6. Method and Process Development of Advanced Atmospheric Plasma Spraying for Thermal Barrier Coatings

    NASA Astrophysics Data System (ADS)

    Mihm, Sebastian; Duda, Thomas; Gruner, Heiko; Thomas, Georg; Dzur, Birger

    2012-06-01

    Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments.

  7. Recent advances in edible coatings for fresh and minimally processed fruits.

    PubMed

    Vargas, Maria; Pastor, Clara; Chiralt, Amparo; McClements, D Julian; González-Martínez, Chelo

    2008-06-01

    The development of new edible coatings with improved functionality and performance for fresh and minimally processed fruits is one of the challenges of the post harvest industry. In the past few years, research efforts have focused on the design of new eco-friendly coatings based on biodegradable polymers, which not only reduce the requirements of packaging but also lead to the conversion of by-products of the food industry into value added film-forming components. This work reviews the different coating formulations and applications available at present, as well as the main results of the most recent investigations carried out on the topic. Traditionally, edible coatings have been used as a barrier to minimize water loss and delay the natural senescence of coated fruits through selective permeability to gases. However, the new generation of edible coatings is being especially designed to allow the incorporation and/or controlled release of antioxidants, vitamins, nutraceuticals, and natural antimicrobial agents by means of the application of promising technologies such as nanoencapsulation and the layer-by-layer assembly.

  8. Evaluation of Advanced Solid Lubricant Coatings for Foil Air Bearings Operating at 25 and 500 C

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Fellenstein, James A.; Benoy, Patricia A.

    1998-01-01

    The tribological properties of one chrome oxide and one chrome carbide based solid lubricant coating were evaluated in a partial-arc foil bearing at 25 and 500 C. Start/stop bearing operation up to 20,000 cycles were run under 10 kPa (1.5 psi) static deadweight load. Bearing friction (torque) was measured during the test. Specimen wear and SEM/EDS surface analyses were conducted after testing to understand and elucidate the tribological characteristics observed. The chrome oxide coating which contains both (Ag) and (BaF2/CaF2) for low and high temperature lubrication, exhibited low friction in sliding against Al2O3 coated foils at 25 and 500 C. The chrome carbide coating, which lacked a low temperature lubricant but contained BaF2/CaF2 as a high temperature lubricant, exhibited high friction at 25 C and low friction at 500 C against both bare and Al2O3 coated superalloy foil surfaces. Post test surface analyses suggest that improved tribological performance is exhibited when a lubricant film from the coating transfers to the foil surface.

  9. Advanced treatment of cephalosporin pharmaceutical wastewater by nano-coated electrode and perforated electrode.

    PubMed

    Yang, Bo; Zuo, Jiane; Gan, Lili; Yu, Xin; Liu, Fenglin; Tang, Xinyao; Wang, Yajiao

    2014-09-19

    The objective of this study was to investigate the degradation of nonbiodegradable organic pollutants in biologically cephalosporin pharmaceutical wastewater using different electrodes such as non-nano-scale electrode (traditional coated), nano-scale (nano-coated) electrode, and perforated electrode after biotreatment. The traditional coated electrode plate, nano-coated electrode plate, and two different perforated titanium dioxide (TiO2) electrode plates with an average pore size of 10 μm and 20 μm were chosen as the anode. The results demonstrated that traditional coated electrode, nano-scale electrode, and perforated electrode could effectively remove nonbiodegradable organic pollutants from pharmaceutical wastewater. The perforated electrode with an average pore size of 10 μm exhibited the best degradation effect with a 90 % decrease in the chemical oxygen demand (COD) (COD content reduced from 320 mg L(-1) to 32 mg L(-1)). During catalytic degradation, the electrical conductivity of pharmaceutical wastewater increased and the pH increased and finally reached equilibrium. It was also found that the perforated TiO2 electrode produced relatively large amounts of dissolved oxygen during the catalytic oxidation process, reaching above 4 mg L(-1), whereas the nano-coated electrode produced little dissolved oxygen. The biotoxicities of all wastewater samples increased firstly then decreased slightly during the electrical catalytic oxidation, but the final biotoxicities were all higher than initial ones.

  10. Low Friction Property of Diamond-Like Carbon Coating Films and Oxygen Transmission Ratio of Amorphous Carbon Films Deposited by Advanced Coating Processes

    NASA Astrophysics Data System (ADS)

    Watanabe, Toshiyuki; Kano, Makoto; Yoshida, Kentaro; Suzuki, Tetsuya

    2012-09-01

    The topics of the applied technology of amorphous carbon film to reduce friction using diamond-like carbon (DLC) coated by the vacuum arc ion plating process and to improve the gas barrier property using the amorphous carbon film by the atmospheric pressure plasma process are introduced with the basic experimental results. For reducing friction, the super low friction coefficient below 0.01 has been found when the tetrahedral amorphous carbon coating deposited by T-shape filtered arc deposition method [ta-C(T)] was evaluated the friction property under oleic acid lubrication at pure sliding condition. It was thought that the low share strength tribofilm composed of water and oleic acid mono-layer seemed to be formed on the sliding interface. For gas barrier performance, the amorphous carbon film deposited by the atmospheric pressure plasma chemical vapour deposition (CVD) technique on poly(ethylene terephthalate) (PET) substrate was improved the oxygen transmission ratio (OTR) around 30% compared with that of uncoated PET substrate. These advanced performance obtained by the optimum material combination of DLC with lubricant and the original atmospheric pressure plasma CVD technique are expected to be applied on the actual application for the different types of the industrial fields in near future.

  11. Role of monomer sequence and backbone structure in polypeptoid and polypeptide polymers for anti-fouling applications

    NASA Astrophysics Data System (ADS)

    Patterson, Anastasia; Rizis, Georgios; Wenning, Brandon; Finlay, John; Ober, Christopher; Segalman, Rachel

    Polymeric coatings rely on a fine balance of surface properties to achieve biofouling resistance. Bioinsipired polymers and oligomers provide a modular strategy for the inclusion of multiple functionalities with controlled architecture, sequence and surface properties. In this work, polypeptoid and polypeptide functionalized coatings based on PEO and PDMS block copolymers were compared with respect to surface presentation and fouling by Ulva linza. While polypeptoids and polypeptides are simple isomers of each other, the lack of backbone chirality and hydrogen bonding in polypeptoids leads to surprisingly different surface behavior. Specifically, the polypeptoids surface segregate much more strongly than analogous polypeptide functionalized polymers, which in turn affects the performance of the coating. Indeed, polypeptoid functionalized surfaces were significantly better both in terms of anti-fouling and fouling release than the corresponding polypeptide-bearing polymers. The role of specific monomer sequence and backbone chemistry will be further discussed in this poster.

  12. Advances in far-ultraviolet reflective and transmissive coatings for space applications

    NASA Astrophysics Data System (ADS)

    Rodríguez-de Marcos, Luis; Aznárez, José A.; Méndez, José A.; Larruquert, Juan I.; Vidal-Dasilva, M.; Malvezzi, A. Marco; Giglia, Angelo; Capobianco, Gerardo; Massone, Giuseppe; Fineschi, Silvano; Nannarone, Stefano

    2016-07-01

    Exploitation of far ultraviolet (FUV, 100-200 nm) observations extends to most areas of modern astronomy, from detailed observations of Solar System objects, the interstellar medium, exoplanets, stars and galaxies, to studies of crucial cosmological relevance. Despite several developments in recent decades, yet many observations are not possible due to technical limitations, of which one of the most important is the lack of optical coatings with high throughput. Development and optimization of such efficient FUV coatings have been identified in several roadmap reports as a key goal for future missions. The success of this development will ultimately improve the performance of nowadays feasible optical instruments and will enable new scientific imaging capabilities. GOLD's research is devoted to developing novel coatings with enhanced performance for space optics. Several deposition systems are available for the deposition of multilayer coatings. A deposition system was developed to deposit FUV coatings to satisfy space requirements. It consists of a 75-cm-diameter deposition chamber pumped with a cryo-pump and placed in an ISO-6 clean room. This chamber is available for deposition by evaporation of top-requirement coatings such as Al/ MgF2 mirrors or (Al/MgF2)n multilayer coatings for transmittance filters. A plan to add an Ion-Beam-Sputtering system in this chamber is under way. In this and other chambers at GOLD the following FUV coatings can be prepared: Transmittance filters based on (Al/MgF2)n multilayer coatings. These filters can be designed to have a peak at the FUV spectral line or band of interest and a high peak-to-visible transmittance ratio. Filters can be designed with a peak transmittance at a wavelength as short as 120 nm and with a transmittance in the visible smaller than 10-5. Narrowband reflective coatings peaked close to H Lyman β (102.6 nm) with a reflectance at H Lyman α (121.6 nm) two orders of magnitude below the one at 102.6 nm. Other

  13. Speciation of antifoulant organotin compounds in water

    SciTech Connect

    Van Nguyen, V.; Posey, I.J.; Eng, G.

    1984-01-01

    The fate of several antifoulant organotin compounds, Ph/sub 3/SnOH, Ph/sub 3/SnCl, and Ph/sub 3/SnOCOCH/sub 3/ in water has been investigated using IR spectroscopy and thin-layer chromatography. Except for the residue resulting from the extract of aqueous Ph/sub 3/SnOCOCH/sub 3/, the IR spectrum of each residue was identical to that of the starting organotin compound. The IR spectrum of the residue obtained from the chloroform extract of aqueous Ph/sub 3/SnOCOCH/sub 3/ which has been shaken for 7 days showed the presence of Ph/sub 3/SnOH as confirmed by the presence of a small doublet around 910 and 897 cm/sup -1/. Also, the pH measurement of each of the aqueous Ph/sub 3/SnX solutions decreased with time. These results are interpreted to suggest that the organotin compounds studied ionize in aqueous media. Thin-layer chromatography results give further support to these findings. The study suggests that the X group in the compounds of the type Ph/sub 3/SnX is labile in polar solvents and that Ph/sub 3/SnOH and/or Ph/sub 3/SnX are the species formed in aqueous solution. 6 references, 1 figure, 2 tables.

  14. Advanced Anticorrosion Coating Materials Derived from Sunflower Oil with Bifunctional Properties.

    PubMed

    Balakrishnan, Thiruparasakthi; Sathiyanarayanan, Sadagopan; Mayavan, Sundar

    2015-09-09

    High-performance barrier films preventing permeation of moisture, aggressive chloride ions, and corrosive acids are important for many industries ranging from food to aviation. In the current study, pristine sunflower oil was used to form uniform adherent films on iron (Fe) via a simple single-step thermal treatment (without involving any initiator/mediator/catalyst). Oxidation of oil on heating results in a highly conjugated (oxidized) crystalline lamellar network with interlayer separation of 0.445 nm on Fe. The electrochemical corrosion tests proved that the coating exhibits superior anticorrosion performance with high coating resistance (>10(9) ohm cm2) and low capacitance values (<10(-10) F cm(-2)) as compared to bare Fe, graphene, and conducting polymer based coatings in 1 M hydrochloric acid solutions. The electrochemical analyses reveal that the oil coatings developed in this study provided a two-fold protection of passivation from the oxide layer and barrier from polymeric films. It is clearly observed that there is no change in structure, morphology, or electrochemical properties even after a prolonged exposure time of 80 days. This work indicates the prospect of developing highly inert, environmentally green, nontoxic, and micrometer level passivating barrier coatings from more sustainable and renewable sources, which can be of interest for numerous applications.

  15. Advanced ceramic coating development for industrial/utility gas turbine applications

    NASA Technical Reports Server (NTRS)

    Andersson, C. A.; Lau, S. K.; Bratton, R. J.; Lee, S. Y.; Rieke, K. L.; Allen, J.; Munson, K. E.

    1982-01-01

    The effects of ceramic coatings on the lifetimes of metal turbine components and on the performance of a utility turbine, as well as of the turbine operational cycle on the ceramic coatings were determined. When operating the turbine under conditions of constant cooling flow, the first row blades run 55K cooler, and as a result, have 10 times the creep rupture life, 10 times the low cycle fatigue life and twice the corrosion life with only slight decreases in both specific power and efficiency. When operating the turbine at constant metal temperature and reduced cooling flow, both specific power and efficiency increases, with no change in component lifetime. The most severe thermal transient of the turbine causes the coating bond stresses to approach 60% of the bond strengths. Ceramic coating failures was studied. Analytic models based on fracture mechanics theories, combined with measured properties quantitatively assessed both single and multiple thermal cycle failures which allowed the prediction of coating lifetime. Qualitative models for corrosion failures are also presented.

  16. Advanced oxidation of natural organic matter using hydrogen peroxide and iron-coated pumice particles.

    PubMed

    Kitis, M; Kaplan, S S

    2007-08-01

    The oxidative removal of natural organic matter (NOM) from waters using hydrogen peroxide and iron-coated pumice particles as heterogeneous catalysts was investigated. Two NOM sources were tested: humic acid solution and a natural source water. Iron coated pumice removed about half of the dissolved organic carbon (DOC) concentration at a dose of 3000 mg l(-1) in 24 h by adsorption only. Original pumice and peroxide dosed together provided UV absorbance reductions as high as 49%, mainly due to the presence of metal oxides including Al(2)O(3), Fe(2)O(3) and TiO(2) in the natural pumice, which are known to catalyze the decomposition of peroxide forming strong oxidants. Coating the original pumice particles with iron oxides significantly enhanced the removal of NOM with peroxide. A strong linear correlation was found between iron contents of coated pumices and UV absorbance reductions. Peroxide consumption also correlated with UV absorbance reduction. Control experiments proved the effective coating and the stability of iron oxide species bound on pumice surfaces. Results overall indicated that in addition to adsorptive removal of NOM by metal oxides on pumice surfaces, surface reactions between iron oxides and peroxide result in the formation of strong oxidants, probably like hydroxyl radicals, which further oxidize both adsorbed NOM and remaining NOM in solution, similar to those in Fenton-like reactions.

  17. Antifouling activities of β-cyclodextrin stabilized peg based silver nanocomposites

    NASA Astrophysics Data System (ADS)

    Punitha, N.; Saravanan, P.; Mohan, R.; Ramesh, P. S.

    2017-01-01

    Self-polishing polymer composites which release metal biocide in a controlled rate have been widely used in the design of antimicrobial agents and antifouling coatings. The present work focuses on the environmental friendly green synthesis of PEG based SNCs and their application to biocidal activity including marine biofouling. Biocompatible polymer β-CD and adhesive resistance polymer PEG were used to functionalize the SNPs and the as synthesized SNCs exhibit excellent micro fouling activities. The structural and optical properties were confirmed by XRD and UV-visible techniques respectively. The particle surface and cross sectional characteristics were examined by SEM-EDS, HR-TEM, AFM and FTIR. The surface potential was evaluated using ZP analysis and assessment of antibiofouling property was investigated using static immersion method.

  18. Mussel-Inspired Anchoring of Polymer Loops That Provide Superior Surface Lubrication and Antifouling Properties.

    PubMed

    Kang, Taegon; Banquy, Xavier; Heo, Jinhwa; Lim, Chanoong; Lynd, Nathaniel A; Lundberg, Pontus; Oh, Dongyeop X; Lee, Han-Koo; Hong, Yong-Ki; Hwang, Dong Soo; Waite, John Herbert; Israelachvili, Jacob N; Hawker, Craig J

    2016-01-26

    We describe robustly anchored triblock copolymers that adopt loop conformations on surfaces and endow them with unprecedented lubricating and antifouling properties. The triblocks have two end blocks with catechol-anchoring groups and a looping poly(ethylene oxide) (PEO) midblock. The loops mediate strong steric repulsion between two mica surfaces. When sheared at constant speeds of ∼2.5 μm/s, the surfaces exhibit an extremely low friction coefficient of ∼0.002-0.004 without any signs of damage up to pressures of ∼2-3 MPa that are close to most biological bearing systems. Moreover, the polymer loops enhance inhibition of cell adhesion and proliferation compared to polymers in the random coil or brush conformations. These results demonstrate that strongly anchored polymer loops are effective for high lubrication and low cell adhesion and represent a promising candidate for the development of specialized high-performance biomedical coatings.

  19. Antifouling strategies: history and regulation, ecological impacts and mitigation.

    PubMed

    Dafforn, Katherine A; Lewis, John A; Johnston, Emma L

    2011-03-01

    Biofouling increases drag on marine vessels resulting in higher fuel consumption and can also facilitate the transport of harmful non-indigenous species (NIS). Antifouling technologies incorporating biocides (e.g., copper and tributyltin) have been developed to prevent settlement of organisms on vessels, but their widespread use has introduced high levels of contamination into the environment and raised concerns about their toxic effects on marine communities. The recent global ban on tributyltin (1 January 2008) and increasing regulation of copper have prompted research and development of non-toxic paints. This review synthesises existing information regarding the ecological impact of biocides in a wide range of organisms and highlights directions for the management of antifouling paints. We focus particularly on representatives of the recent past (copper and tributyltin) and present (copper and 'booster') biocides. We identify knowledge gaps in antifouling research and provide recommendations relating to the regulation and phasing-out of copper.

  20. MICROSTRUCTURAL EXAMINATION AND DEUTERIUM PERMEATION TESTING OF ADVANCED COATINGS FOR TRITIUM SERVICE

    SciTech Connect

    Korinko, P.

    2004-01-24

    A plant directed research and development task to develop and study new, improved, and low cost tritium permeation barriers was initiated in FY02. The project was intended to determine the permeation rate and permeation reduction factor of substrate materials and coated materials. The samples were characterized for microstructural and microchemical consistency. Permeation tests were also run. The sample geometry and sample sealing method selected for the coatings posed significant schedule and technical challenges. Diffusivity were consistent with published values but permeation data exhibited an unexpected sample to sample variation. The effort has lead to an improved sample design that will be used to support a Process Development task.

  1. Analytical investigation of thermal barrier coatings for advanced power generation combustion turbines

    NASA Technical Reports Server (NTRS)

    Amos, D. J.

    1977-01-01

    An analytical evaluation was conducted to determine quantitatively the improvement potential in cycle efficiency and cost of electricity made possible by the introduction of thermal barrier coatings to power generation combustion turbine systems. The thermal barrier system, a metallic bond coat and yttria stabilized zirconia outer layer applied by plasma spray techniques, acts as a heat insulator to provide substantial metal temperature reductions below that of the exposed thermal barrier surface. The study results show the thermal barrier to be a potentially attractive means for improving performance and reducing cost of electricity for the simple, recuperated, and combined cycles evaluated.

  2. Recent advances in modified atmosphere packaging and edible coatings to maintain quality of fresh-cut fruits and vegetables.

    PubMed

    Ghidelli, Christian; Pérez-Gago, María B

    2016-07-28

    Processing of fruits and vegetables generates physiological stresses in the still living cut tissue, leading to quality deterioration and shorter shelf-life as compared with fresh intact produces. Several strategies can be implemented with the aim to reduce the rate of deterioration of fresh-cut commodities. Such strategies include low temperature maintenance from harvest to retail and the application of physical and chemical treatments such as modified atmosphere packaging (MAP) with low O2 and high CO2 levels and antioxidant dips. Other technologies such as edible coatings with natural additives, new generation of coatings using nanotechnological solutions such as nanoparticles, nanoencapsulation, and multilayered systems, and non-conventional atmospheres such as the use of pressurized inert/noble gases and high levels of O2 have gained a lot of interest as a possibility to extend the shelf life of minimally processed fruits and vegetables. However, the high perishability of these products challenges in many cases their marketability by not achieving sufficient shelf life to survive the distribution system, requiring the combination of treatments to assure safety and quality. This review reports the recent advances in the use of MAP, edible coatings, and the combined effect of both technologies to extend the shelf life of fresh-cut fruits and vegetables.

  3. Advanced biopolymer-coated drug-releasing titania nanotubes (TNTs) implants with simultaneously enhanced osteoblast adhesion and antibacterial properties.

    PubMed

    Kumeria, Tushar; Mon, Htwe; Aw, Moom Sinn; Gulati, Karan; Santos, Abel; Griesser, Hans J; Losic, Dusan

    2015-06-01

    Here, we report on the development of advanced biopolymer-coated drug-releasing implants based on titanium (Ti) featuring titania nanotubes (TNTs) on its surface. These TNT arrays were fabricated on the Ti surface by electrochemical anodization, followed by the loading and release of a model antibiotic drug, gentamicin. The osteoblastic adhesion and antibacterial properties of these TNT-Ti samples are significantly improved by loading antibacterial payloads inside the nanotubes and modifying their surface with two biopolymer coatings (PLGA and chitosan). The improved osteoblast adhesion and antibacterial properties of these drug-releasing TNT-Ti samples are confirmed by the adhesion and proliferation studies of osteoblasts and model Gram-positive bacteria (Staphylococcus epidermidis). The adhesion of these cells on TNT-Ti samples is monitored by fluorescence and scanning electron microscopies. Results reveal the ability of these biopolymer-coated drug-releasing TNT-Ti substrates to promote osteoblast adhesion and proliferation, while effectively preventing bacterial colonization by impeding their proliferation and biofilm formation. The proposed approach could overcome inherent problems associated with bacterial infections on Ti-based implants, simultaneously enabling the development of orthopedic implants with enhanced and synergistic antibacterial functionalities and bone cell promotion.

  4. NASA's Advanced Environmental Barrier Coatings Development for SiC/SiC Ceramic Matrix Composites: Understanding Calcium Magnesium Alumino-Silicate (CMAS) Degradations and Resistance

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming

    2014-01-01

    Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is essential to the viability and reliability of the envisioned CMC engine component applications, ensuring integrated EBC-CMC system durability and designs are achievable for successful applications of the game-changing component technologies and lifing methodologies.This paper will emphasize recent NASA environmental barrier coating developments for SiCSiC turbine airfoil components, utilizing advanced coating compositions, state-of-the-art processing methods, and combined mechanical and environment testing and durability evaluations. The coating-CMC degradations in the engine fatigue-creep and operating environments are particularly complex; one of the important coating development aspects is to better understand engine environmental interactions and coating life debits, and we have particularly addressed the effect of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the durability of the environmental barrier coating systems, and how the temperature capability, stability and cyclic life of the candidate rare earth oxide and silicate coating systems will be impacted in the presence of the CMAS at high temperatures and under simulated heat flux conditions. Advanced environmental barrier coating systems, including HfO2-Si with rare earth dopant based bond coat systems, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

  5. Evaluation of dihydrooroidin as an antifouling additive in marine paint

    PubMed Central

    Melander, Christian; Moeller, Peter D. R.; Ballard, T. Eric; Richards, Justin J.; Huigens, Robert W.; Cavanagh, John

    2013-01-01

    Methods used to deter biofouling of underwater structures and marine vessels present a serious environmental issue and are both problematic and costly for government and commercial marine vessels worldwide. Current antifouling methods include compounds that are toxic to aquatic wildlife and marine ecosystems. Dihydrooroidin (DHO) was shown to completely inhibit Halomonas pacifica biofilms at 100 μM in a static biofilm inhibition assay giving precedence for the inhibition of other marine-biofilm-forming organisms. Herein we present DHO as an effective paint-based, non-cytotoxic, antifouling agent against marine biofouling processes in a marine mesocosm. PMID:23874076

  6. Advanced formulation design of venlafaxine hydrochloride coated and triple-layer tablets containing hypromellose.

    PubMed

    Gohel, Mukesh; Bariya, Shital H

    2009-01-01

    The purpose of this research work was to develop venlafaxine hydrochloride-coated and layered matrix tablets using hypromellose adopting wet granulation technique. The granules and the tablets were characterized. The monolithic tablets were coated with different ratios of ethyl cellulose and hypromellose. The in vitro dissolution study was performed in distilled water. In the layered tablets, the middle layer containing drug was covered with barrier layers containing high viscosity grade hypromellose. Simplex lattice design was used for formulating the layered tablets. The dissolution study of the optimized batches and a reference product was carried out in 0.1 N HCl, phosphate buffer and hydroalcoholic solution. Burst drug release was exhibited by the uncoated tablets, probably due to high aqueous solubility of venlafaxine HCl. The coated tablets showed sustained drug release without burst effect. The drug release was best explained by Weibull model. A unified Weibull equation was evolved to express drug release from the coated tablets. The layered tablets also exhibited sustained release without burst effect due to effective area reduction. The optimized batches showed identical drug release in 0.1 N HCl, phosphate buffer and 10% v/v aqueous alcohol. Layered tablets may well be adopted by the industry due to the possibility of achieving a high production rate.

  7. Development of Advanced Coating Techniques for Highly-durable Casting Dies

    NASA Astrophysics Data System (ADS)

    Tanaka, S.; Takagi, M.; Mano, T.

    2013-03-01

    In order to improve the durability of aluminum die-casting molds, we applied microstructure-controlled PVD coating techniques. Single-layer and multilayer films consisting of chromium nitride (CrN) or titanium aluminum nitride (TiAlN) were prepared using an ion plating process. Structures of multilayer films were observed using transmission electron microscopy. Pin-shaped mold steel specimens coated with each of the films were soaked in the molten aluminum alloy at 953 K different periods of time, and the amount of weight loss due to erosion was evaluated. The weight losses for the multilayer CrN and TiAlN specimens were found to be less than those for the single-layer specimens. As a practical test, five specimens of core pins used in aluminum die casting of automobile parts were coated with multilayer films, and the number of maintenance operations required to remove aluminum alloy remaining on the specimen surfaces after several thousand castings was counted and compared with six control specimens (core pins treated using a commercial salt bath diffusion process). The number of maintenance operations for CrN- and TiAlN-based multilayer-coated core pins was found to be lower than for the control specimens.

  8. Advanced mortar coatings for cultural heritage protection. Durability towards prolonged UV and outdoor exposure.

    PubMed

    Pino, F; Fermo, P; La Russa, M; Ruffolo, S; Comite, V; Baghdachi, J; Pecchioni, E; Fratini, F; Cappelletti, G

    2016-10-01

    In the present work, two kinds of hybrid polymeric-inorganic coatings containing TiO2 or SiO2 particles and prepared starting from two commercial resins (Alpha®SI30 and Bluesil®BP9710) were developed and applied to two kinds of mortars (an air-hardening calcic lime mortar [ALM] and a natural hydraulic lime mortar [HLM]) to achieve better performances in terms of water repellence and consequently damage resistance. The two pure commercial resins were also applied for comparison purposes. Properties of the coated materials and their performance were studied using different techniques such as contact angle measurements, capillary absorption test, mercury intrusion porosimetry, surface free energy, colorimetric measurements and water vapour permeability tests. Tests were also performed to determine the weathering effects on both the commercial and the hybrid coatings in order to study their durability. Thus, exposures to UV radiation, to UV radiation/condensed water cycles and to a real polluted atmospheric environment have been performed. The effectiveness of the hybrid SiO2 based coating was demonstrated, especially in the case of the HLM mortar.

  9. Advanced fiber information systems seed coat neps baseline response from diverse mediums

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An extensive literature search has revealed that no papers have been published regarding selectivity calculation of the AFIS seed coat neps (SCN) determination over interfering material in cotton. A prerequisite to selectivity measurements is to identify suitable fiber medium(s) that give baseline ...

  10. Profile Coating for KB Mirror Applications at the Advanced Photon Source

    NASA Astrophysics Data System (ADS)

    Liu, C.; Assoufid, L.; Macrander, A.; Ice, G.; Tischler, J.

    2002-01-01

    For microfocusing x-ray mirrors, an ellipse shape is desirable for aberration-free optics. However, it is difficult to polish elliptical mirrors to x-ray quality smoothness. A differential coating method to convert a cylindrical mirror to an elliptical one has been previously reported The differential coating was obtained by varying the sputter source power while the mirror was passed through. Here we report a new method of profile coating to achieve the same goal more effectively. In the profile coating, the sputter source power is kept constant, while the substrate is passed over a contoured mask at a constant speed. The mask is placed very close to the substrate level (within 1.0 mm) on a shield-can over the sputter gun. Four-inch-diameter Si wafers were coated through a 100-mm-long by 152-mm-wide aperture on the top of the shield-can. The thickness distribution was then obtained using a spectroscopic ellipsometer with computer-controlled X-Y translation stages. A model has been developed to fit the measured thickness distribution of stationary growth. The relative thickness weightings are then digitized at every point 1 mm apart for the entire open area of the aperture. When the substrate is moving across the shield-can during a deposition, the film thickness is directly proportional to the length of the opening on the can along the moving direction. By equating the summation of relative weighting to the required relative thickness at the same position, the length of the opening at that position can be determined. By repeating the same process for the whole length of the required profile, a contour can be obtained for a desired thickness profile. The contoured mask is then placed on the opening of the shield-can. The number of passes and the moving speed of the substrate are determined according to the required thickness and the growth-rate calibration. The mirror coating profile is determined from the ideal surface figure of a focus ellipse and that obtained

  11. Profile coating for KB mirror applications at the Advanced Photon Source

    NASA Astrophysics Data System (ADS)

    Liu, Chian; Assoufid, L.; Macrander, Albert T.; Ice, Gene E.; Tischler, J. Z.

    2002-12-01

    For microfocusing x-ray mirrors, an ellipse shape is desirable for aberration-free optics. However, it is difficult to polish elliptical mirrors to x-ray quality smoothness. A differential coating method to convert a cylindrical mirror to an elliptical one has been previously reported The differential coating was obtained by varying the sputter source power while the mirror was passed through. Here we report a new method of profile coating to achieve the same goal more effectively. In the profile coating, the sputter source power is kept constant, while the substrate is passed over a contoured mask at a constant speed. The mask is placed very close to the substrate level (within 1.0 mm) on a shield-can over the sputter gun. Four-inch-diameter Si wafers were coated through a 100-mm-long by 152-mm-wide aperture on the top of the shield-can. The thickness distribution was then obtained using a spectroscopic ellipsometer with computer-controlled X-Y translation stages. A model has been developed to fit the measured thickness distribution of stationary growth. The relative thickness weightings are then digitized at every point 1 mm apart for the entire open area of the aperture. When the substrate is moving across the shield-can during a deposition, the film thickness is directly proportional to the length of the opening on the can along the moving direction. By equating the summation of relative weighting to the required relative thickness at the same position, the length of the opening at that position can be determined. By repeating the same process for the whole length of the required profile, a contour can be obtained for a desired thickness profile. The contoured mask is then placed on the opening of the shield-can. The number of passes and the moving speed of the substrate are determined according to the required thickness and the growth-rate calibration. The mirror coating profile is determined from the ideal surface figure of a focus ellipse and that obtained

  12. Carbon-coated Li3 N nanofibers for advanced hydrogen storage.

    PubMed

    Xia, Guanglin; Li, Dan; Chen, Xiaowei; Tan, Yingbin; Tang, Ziwei; Guo, Zaiping; Liu, Huakun; Liu, Zongwen; Yu, Xuebin

    2013-11-20

    3D porous carbon-coated Li3 N nanofibers are successfully fabricated via the electrospinning technique. The as-prepared nanofibers exhibit a highly improved hydrogen-sorption performance in terms of both thermodynamics and kinetics. More interestingly, a stable regeneration can be achieved due to the unique structure of the nanofibers, over 10 cycles of H2 sorption at a temperature as low as 250 °C.

  13. Corrosion Protection of Al Alloys for Aircraft by Coatings With Advanced Properties and Enhanced Performance

    DTIC Science & Technology

    2007-12-20

    Sim6es, D. E. Tallman, G. P. Bierwagen, "Electrochemical Behaviour of a Mg-Rich Primer in the Protection of Al Alloys ," Corrosion Science 48 (2006...December 20, 200 Final Report July 1, 2004-June 30, 2007 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER Corrosion Protection of Al Alloys for Aircraft by...Prof. Dennis E. Tallman: A) New Scanning Probe Studies of Novel Cr-free Active Coatings B) Examination of the Influence of Surface Preparation of Al

  14. Latest Researches Advances of Plasma Spraying: From Splat to Coating Formation

    NASA Astrophysics Data System (ADS)

    Fauchais, P.; Vardelle, M.; Goutier, S.

    2016-12-01

    The plasma spray process with solid feedstock, mainly ceramics powders, studied since the sixties is now a mature technology. The plasma jet and particle in-flight characterizations are now well established. The use of computer-aided robot trajectory allows spraying on industrial parts with complex geometries. Works about splat formation have shown the importance of: the substrate preheating over the transition temperature to get rid of adsorbates and condensates, substrate chemistry, crystal structure and substrate temperature during the whole coating process. These studies showed that coating properties strongly depend on the splat formation and layering. The first part of this work deals with a summary of conventional plasma spraying key points. The second part presents the current knowledge in plasma spraying with liquid feedstock, technology developed for about two decades with suspensions of particles below micrometers or solutions of precursors that form particles a few micrometers sized through precipitation. Coatings are finely structured and even nanostructured with properties arousing the interest of researchers. However, the technology is by far more complex than the conventional ones. The main conclusions are that models should be developed further, plasma torches and injection setups adapted, and new measuring techniques to reliably characterize these small particles must be designed.

  15. Low-Thermal-Conductivity Pyrochlore Oxide Materials Developed for Advanced Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Zhu, Dong-Ming

    2005-01-01

    When turbine engines operate at higher temperatures, they consume less fuel, have higher efficiencies, and have lower emissions. The upper-use temperatures of the base materials (superalloys, silicon-based ceramics, etc.) used for the hot-section components of turbine engines are limited by the physical, mechanical, and corrosion characteristics of these materials. Thermal barrier coatings (TBCs) are applied as thin layers on the surfaces of these materials to further increase the operating temperatures. The current state-of-the-art TBC material in commercial use is partially yttria-stabilized zirconia (YSZ), which is applied on engine components by plasma spraying or by electron-beam physical vapor deposition. At temperatures higher than 1000 C, YSZ layers are prone to sintering, which increases thermal conductivity and makes them less effective. The sintered and densified coatings can also reduce thermal stress and strain tolerance, which can reduce the coating s durability significantly. Alternate TBC materials with lower thermal conductivity and better sintering resistance are needed to further increase the operating temperature of turbine engines.

  16. The four dimensions of clathrin coats in living cells measured by advanced fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Davoust, Jean; Cosson, Pierre

    1991-05-01

    After microinjection into cultured Vero cells, rhodamine-labeled clathrin triskelions gave rise to a punctuate fluorescence pattern typical for clathrin, with two major localizations: the plasma membrane and the perinuclear region of the cells. We analyzed clathrin motion by Fluorescence Recovery After Photobleaching and its 3 dimensional distribution by Confocal Microscopy. Altogether, 55% of total clathrin is polymerized into coats which are turning over with a half time of 11 seconds and 45% of total diffuses freely in the cytoplasm. Various conditions known to affect membrane traffic were investigated. Cytosolic acidification or ATP depletion stabilized the polymerized clathrin coats without modifying the ratio of free versus polymerized clathrin. Low temperature (6 °C) or hypertonic media dramatically increased both the stability and the amount of the polymerized clathrin. We conclude that ATP and pH homeostasis are needed to support a very high turnover of the clathrin coats in living cells whereas low temperature and high osmotic strength promote an extensive polymerization of clathrin.

  17. Influence of photo-induced superhydrophilicity of titanium dioxide nanoparticles on the anti-fouling performance of ultrafiltration membranes

    NASA Astrophysics Data System (ADS)

    Madaeni, S. S.; Ghaemi, N.; Alizadeh, A.; Joshaghani, M.

    2011-05-01

    Fouling is one of the most present prominent problems in almost all membrane processes. An increase in the membrane hydrophilicity is one of the effective ways to improve the membrane resistance to fouling. In this research, TiO 2 nanoparticles were deposited on the surface of composite ultrafiltration (UF) membrane, and then irradiated by ultraviolet (UV) light. The coating of the membrane surface with TiO 2 nanoparticles and radiation with (UV) light led to the considerable increase of hydrophilicity on the membrane surface. The deposition of TiO 2 nanoparticles was carried out through coordinance bonds with OH functional groups of the polymer on the membrane surface. The flux through a coated and (UV) light radiated membrane was increased to a large extent compared to a virgin membrane. In this research, the effect of different concentrations of TiO 2 nanoparticles in the presence and absence of (UV) irradiation was investigated, and the role of increasing of hydrophilicity on the anti-fouling property of membranes was studied. In order to characterize the membranes FTIR, XRD, SEM, water contact angle and cross-flow filtration were employed. This procedure is a useful technique for improvement of hydrophilicity to decrease (increase) fouling (anti-fouling performance) and enhance the permeation of membranes.

  18. Optically and biologically active mussel protein-coated double-walled carbon nanotubes.

    PubMed

    Jung, Yong Chae; Muramatsu, Hiroyuki; Fujisawa, Kazunori; Kim, Jin Hee; Hayashi, Takuya; Kim, Yoong Ahm; Endo, Morinobu; Terrones, Mauricio; Dresselhaus, Mildred S

    2011-12-02

    A method of dispersing strongly bundled double-walled carbon nanotubes (DWNTs) via a homogeneous coating of mussel protein in an aqueous solution is presented. Optical activity, mechanical strength, as well as electrical conductivity coming from the nanotubes and the versatile biological activity from the mussel protein make mussel-coated DWNTs promising as a multifunctional scaffold and for anti-fouling materials.

  19. Antifouling activity of secondary metabolites isolated from chinese marine organisms.

    PubMed

    Li, Yong-Xin; Wu, Hui-Xian; Xu, Ying; Shao, Chang-Lun; Wang, Chang-Yun; Qian, Pei-Yuan

    2013-10-01

    Biofouling results in tremendous economic losses to maritime industries around the world. A recent global ban on the use of organotin compounds as antifouling agents has further raised demand for safe and effective antifouling compounds. In this study, 49 secondary metabolites, including diterpenoids, steroids, and polyketides, were isolated from soft corals, gorgonians, brown algae, and fungi collected along the coast of China, and their antifouling activity was tested against cyprids of the barnacle Balanus (Amphibalanus) amphitrite. Twenty of the compounds were found to inhibit larval settlement significantly at a concentration of 25 μg ml(-1). Two briarane diterpenoids, juncin O (2) and juncenolide H (3), were the most promising non-toxic antilarval settlement candidates, with EC50 values less than 0.13 μg ml(-1) and a safety ratio (LC50/EC50) higher than 400. A preliminary structure-activity relationships study indicated that both furanon and furan moieties are important for antifouling activity. Intriguingly, the presence of hydroxyls enhanced their antisettlement activity.

  20. Antiparasitic, Nematicidal and Antifouling Constituents from Juniperus Berries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A bioassay-guided fractionation of Juniperus procera berries yielded antiparasitic, nematicidal and antifouling constituents, including a wide range of known abietane, pimarane and labdane diterpenes. Among these, abieta-7,13-diene (1) demonstrated in vitro antimalarial activity against Plasmodium f...

  1. Resistance of Coated and Uncoated IR Windows to Seawater Corrosion. Phase V. Summary

    DTIC Science & Technology

    1981-02-01

    competitive substrate materials, uncoated; single-layer AR coatings on germanium and zinc selenide; multiple-layer AR coatings on germanium; overcoatings on...testing) whose plastic coating has torn and peeled away from the substrate , leaving the substrate exposed to corrosion by seawater... 21 12. A coated...II examined two substrate materials (germanium and chalcogenide glass), and antifouling methods such as forced seawater circulation and electric

  2. Test Method Designed to Evaluate Cylinder Liner-Piston Ring Coatings for Advanced Heat Engines

    NASA Technical Reports Server (NTRS)

    Radil, Kevin C.

    1997-01-01

    Research on advanced heat engine concepts, such as the low-heat-rejection engine, have shown the potential for increased thermal efficiency, reduced emissions, lighter weight, simpler design, and longer life in comparison to current diesel engine designs. A major obstacle in the development of a functional advanced heat engine is overcoming the problems caused by the high combustion temperatures at the piston ring/cylinder liner interface, specifically at top ring reversal (TRR). Therefore, advanced cylinder liner and piston ring materials are needed that can survive under these extreme conditions. To address this need, researchers at the NASA Lewis Research Center have designed a tribological test method to help evaluate candidate piston ring and cylinder liner materials for advanced diesel engines.

  3. Antifouling potential of bacteria isolated from a marine biofilm

    NASA Astrophysics Data System (ADS)

    Gao, Min; Wang, Ke; Su, Rongguo; Li, Xuzhao; Lu, Wei

    2014-10-01

    Marine microorganisms are a new source of natural antifouling compounds. In this study, two bacterial strains, Kytococcus sedentarius QDG-B506 and Bacillus cereus QDG-B509, were isolated from a marine biofilm and identified. The bacteria fermentation broth could exert inhibitory effects on the growth of Skeletonema costatum and barnacle larvae. A procedure was employed to extract and identify the antifouling compounds. Firstly, a toxicity test was conducted by graduated pH and liquid-liquid extraction to determine the optimal extraction conditions. The best extraction conditions were found to be pH 2 and 100% petroleum ether. The EC 50 value of the crude extract of K. sedentarius against the test microalgae was 236.7 ± 14.08 μg mL-1, and that of B. cereus was 290.6 ± 27.11 μg mL-1. Secondly, HLB SPE columns were used to purify the two crude extracts. After purification, the antifouling activities of the two extracts significantly increased: the EC 50 of the K. sedentarius extract against the test microalgae was 86.4 ± 3.71 μg mL-1, and that of B. cereus was 92.6 ± 1.47 μg mL-1. These results suggest that the metabolites produced by the two bacterial strains are with high antifouling activities and they should be fatty acid compounds. Lastly, GC-MS was used for the structural elucidation of the compounds. The results show that the antifouling compounds produced by the two bacterial strains are myristic, palmitic and octadecanoic acids.

  4. Marine pollution from antifouling paint particles.

    PubMed

    Turner, Andrew

    2010-02-01

    Antifouling paint particles (APP) are generated during the maintenance of boats and are shed from abandoned structures and grounded ships. Although they afford a highly visible, colourful reflection of contamination in the vicinity of the source, little systematic study has been undertaken regarding the distribution, composition and effects of APP in the wider marine environment. This paper reviews the state of knowledge in respect of APP, with particular emphasis on those generated by recreational boatyards. The likely biogeochemical pathways of the biocidal and non-biocidal metals in current use (mainly Cu and Zn) are addressed in light of recent research and an understanding of the more general behaviour of contaminants in marine systems. Analyses of paint fragment composites from recreational facilities in the UK reveal chemical compositions that are similar to those representing the net signal of the original formulations; significantly, dry weight concentrations of Cu and Zn of up to about 35% and 15%, respectively, are observed and, relative to ambient dusts and sediment, elevated concentrations of other trace metals, like Ba, Cd, Cr, Ni, Pb and Sn, occur. These metals leach more rapidly from APP than a painted surface due to the greater surface area of pigments and additives exposed to the aqueous medium. In suspension, APP are subject to greater and more rapid environmental variation (e.g. salinity, pH, dissolved oxygen) than painted hulls, while settled APP represent an important source of persistent and degradable biocides to poorly circulating environments. Through diffusion and abrasion, high concentrations of contaminants are predicted in interstitial waters that may be accumulated directly by benthic invertebrates. Animals that feed non-selectively and that are exposed to or ingest paint-contaminated sediment are able to accelerate the leaching, deposition and burial of biocides and other substances, and represent an alternative vehicle for

  5. Thermal Properties of Oxides With Magnetoplumbite Structure for Advanced Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Zhu, Dongming; Eslamloo-Grami, Maryam

    2007-01-01

    Oxides having magnetoplumbite structure are promising candidate materials for applications as high temperature thermal barrier coatings because of their high thermal stability, high thermal expansion, and low thermal conductivity. In this study, powders of LaMgAl11O19, GdMgAl11O19, SmMgAl11O19, and Gd0.7Yb0.3MgAl11O19 magnetoplumbite oxides were synthesized by citric acid sol-gel method and hot pressed into disk specimens. The thermal expansion coefficients (CTE) of these oxide materials were measured from room temperature to 1500 C. The average CTE value was found to be approx.9.6x10(exp -6)/C. Thermal conductivity of these magnetoplumbite-based oxide materials was also evaluated using steady-state laser heat flux test method. The effects of doping on thermal properties were also examined. Thermal conductivity of the doped Gd0.7Yb0.3MgAl11O19 composition was found to be lower than that of the undoped GdMgAl11O19. In contrast, thermal expansion coefficient was found to be independent of the oxide composition and appears to be controlled by the magnetoplumbite crystal structure. Thermal conductivity testing of LaMgAl11O19 and LaMnAl11O19 magnetoplumbite oxide coatings plasma sprayed on NiCrAlY/Rene N5 superalloy substrates indicated resistance of these coatings to sintering even at temperatures as high as 1600 C.

  6. Moving graphene devices from lab to market: advanced graphene-coated nanoprobes

    NASA Astrophysics Data System (ADS)

    Hui, Fei; Vajha, Pujashree; Shi, Yuanyuan; Ji, Yanfeng; Duan, Huiling; Padovani, Andrea; Larcher, Luca; Li, Xiao Rong; Xu, Jing Juan; Lanza, Mario

    2016-04-01

    After more than a decade working with graphene there is still a preoccupying lack of commercial devices based on this wonder material. Here we report the use of high-quality solution-processed graphene sheets to fabricate ultra-sharp probes with superior performance. Nanoprobes are versatile tools used in many fields of science, but they can wear fast after some experiments, reducing the quality and increasing the cost of the research. As the market of nanoprobes is huge, providing a solution for this problem should be a priority for the nanotechnology industry. Our graphene-coated nanoprobes not only show enhanced lifetime, but also additional unique properties of graphene, such as hydrophobicity. Moreover, we have functionalized the surface of graphene to provide piezoelectric capability, and have fabricated a nano relay. The simplicity and low cost of this method, which can be used to coat any kind of sharp tip, make it suitable for the industry, allowing production on demand.After more than a decade working with graphene there is still a preoccupying lack of commercial devices based on this wonder material. Here we report the use of high-quality solution-processed graphene sheets to fabricate ultra-sharp probes with superior performance. Nanoprobes are versatile tools used in many fields of science, but they can wear fast after some experiments, reducing the quality and increasing the cost of the research. As the market of nanoprobes is huge, providing a solution for this problem should be a priority for the nanotechnology industry. Our graphene-coated nanoprobes not only show enhanced lifetime, but also additional unique properties of graphene, such as hydrophobicity. Moreover, we have functionalized the surface of graphene to provide piezoelectric capability, and have fabricated a nano relay. The simplicity and low cost of this method, which can be used to coat any kind of sharp tip, make it suitable for the industry, allowing production on demand. Electronic

  7. Advanced Fabrication Method for the Preparation of MOF Thin Films: Liquid-Phase Epitaxy Approach Meets Spin Coating Method.

    PubMed

    Chernikova, Valeriya; Shekhah, Osama; Eddaoudi, Mohamed

    2016-08-10

    Here, we report a new and advanced method for the fabrication of highly oriented/polycrystalline metal-organic framework (MOF) thin films. Building on the attractive features of the liquid-phase epitaxy (LPE) approach, a facile spin coating method was implemented to generate MOF thin films in a high-throughput fashion. Advantageously, this approach offers a great prospective to cost-effectively construct thin-films with a significantly shortened preparation time and a lessened chemicals and solvents consumption, as compared to the conventional LPE-process. Certainly, this new spin-coating approach has been implemented successfully to construct various MOF thin films, ranging in thickness from a few micrometers down to the nanometer scale, spanning 2-D and 3-D benchmark MOF materials including Cu2(bdc)2·xH2O, Zn2(bdc)2·xH2O, HKUST-1, and ZIF-8. This method was appraised and proved effective on a variety of substrates comprising functionalized gold, silicon, glass, porous stainless steel, and aluminum oxide. The facile, high-throughput and cost-effective nature of this approach, coupled with the successful thin film growth and substrate versatility, represents the next generation of methods for MOF thin film fabrication. Therefore, paving the way for these unique MOF materials to address a wide range of challenges in the areas of sensing devices and membrane technology.

  8. Advances in the Development of a WCl6 CVD System for Coating UO2 Powders with Tungsten

    NASA Technical Reports Server (NTRS)

    Mireles, Omar R.; Tieman, Alyssa; Broadway, Jeramie; Hickman, Robert

    2013-01-01

    W-UO2 CERMET fuels are under development to enable Nuclear Thermal Propulsion (NTP) for deep space exploration. Research efforts with an emphasis on fuel fabrication, testing, and identification of potential risks is underway. One primary risk is fuel loss due to CTE mismatch between W and UO2 and the grain boundary structure of W particles resulting in higher thermal stresses. Mechanical failure can result in significant reduction of the UO2 by hot hydrogen. Fuel loss can be mitigated if the UO2 particles are coated with a layer of high density tungsten before the consolidation process. This paper discusses the work to date, results, and advances of a fluidized bed chemical vapor deposition (CVD) system that utilizes the H2-WCl6 reduction process. Keywords: Space, Nuclear, Thermal, Propulsion, Fuel, CERMET, CVD, Tungsten, Uranium

  9. Nano-silica fabricated with silver nanoparticles: antifouling adsorbent for efficient dye removal, effective water disinfection and biofouling control

    NASA Astrophysics Data System (ADS)

    Das, Sujoy K.; Khan, Md. Motiar R.; Parandhaman, T.; Laffir, Fathima; Guha, Arun K.; Sekaran, G.; Mandal, Asit Baran

    2013-05-01

    A nano-silica-AgNPs composite material is proposed as a novel antifouling adsorbent for cost-effective and ecofriendly water purification. Fabrication of well-dispersed AgNPs on the nano-silica surface, designated as NSAgNP, has been achieved through protein mediated reduction of silver ions at ambient temperature for development of sustainable nanotechnology. The coated proteins on AgNPs led to the formation of stable NSAgNP and protected the AgNPs from oxidation and other ions commonly present in water. The NSAgNP exhibited excellent dye adsorption capacity both in single and multicomponent systems, and demonstrated satisfactory tolerance against variations in pH and dye concentration. The adsorption mainly occurred through electrostatic interaction, though π-π interaction and pore diffusion also contributed to the process. Moreover, the NSAgNP showed long-term antibacterial activity against both planktonic cells and biofilms of Gram-negative Escherichia coli and Pseudomonas aeruginosa. The antibacterial activity of AgNPs retarded the initial attachment of bacteria on NSAgNP and thus significantly improved the antifouling properties of the nanomaterial, which further inhibited biofilm formation. Scanning electron and fluorescence microscopic studies revealed that cell death occurred due to irreversible damage of the cell membrane upon electrostatic interaction of positively charged NSAgNP with the negatively charged bacterial cell membrane. The high adsorption capacity, reusability, good tolerance, removal of multicomponent dyes and E. coli from the simulated contaminated water and antifouling properties of NSAgNP will provide new opportunities to develop cost-effective and ecofriendly water purification processes.A nano-silica-AgNPs composite material is proposed as a novel antifouling adsorbent for cost-effective and ecofriendly water purification. Fabrication of well-dispersed AgNPs on the nano-silica surface, designated as NSAgNP, has been achieved through

  10. Additive Manufacturing of Advanced High Temperature Masking Fixtures for EBPVD TBC Coating

    SciTech Connect

    List, III, Frederick Alyious; Feuerstein, Albert; Dehoff, Ryan; Kirka, Michael; Carver, Keith

    2016-03-30

    The purpose of this Manufacturing Demonstration Facility (MDF) technical collaboration project between Praxair Surface Technologies, Inc. (PST) and Oak Ridge National Laboratory (ORNL) was to develop an additive manufacturing process to fabricate next generation high temperature masking fixtures for coating of turbine airfoils with ceramic Thermal Barrier Coatings (TBC) by the Electron Beam Physical Vapor Deposition (EBPVD) process. Typical masking fixtures are sophisticated designs and require complex part manipulation in order to achieve the desired coating distribution. Fixtures are typically fabricated from high temperature nickel (Ni) based superalloys. The fixtures are fabricated from conventional processes by welding of thin sheet material into a complex geometry, to decrease the weight load for the manipulator and to reduce the thermal mass of the fixture. Recent attempts have been made in order to fabricate the fixtures through casting, but thin walled sections are difficult to cast and have high scrap rates. This project focused on understanding the potential for fabricating high temperature Ni based superalloy fixtures through additive manufacturing. Two different deposition processes; electron beam melting (EBM) and laser powder bed fusion were evaluated to determine the ideal processing route of these materials. Two different high temperature materials were evaluated. The high temperature materials evaluated were Inconel 718 and another Ni base alloy, designated throughout the remainder of this document as Alloy X, as the alloy composition is sensitive. Inconel 718 is a more widely utilized material for additive manufacturing although it is not currently the material utilized for current fixtures. Alloy X is the alloy currently used for the fixtures, but is not a commercially available alloy for additive manufacturing. Praxair determined it was possible to build the fixture using laser powder bed technology from Inconel 718. ORNL fabricated the fixture

  11. Progress report on understanding AFIS seed coat nep levels in pre-opened slivers on the Advanced Fiber Information System (AFIS)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Advanced Fiber Information System (AFIS) is utilized in this segment of the research project to study how seed coat neps are measured. A patent search was conducted, and studied to assist with the understanding of the AFIS measurement of this impurity in raw cotton. The older AFIS 2 is primari...

  12. The ion beam sputtering facility at KURRI: Coatings for advanced neutron optical devices

    NASA Astrophysics Data System (ADS)

    Hino, Masahiro; Oda, Tatsuro; Kitaguchi, Masaaki; Yamada, Norifumi L.; Tasaki, Seiji; Kawabata, Yuji

    2015-10-01

    We describe a film coating facility for the development of multilayer mirrors for use in neutron optical devices that handle slow neutron beams. Recently, we succeeded in fabricating a large neutron supermirror with high reflectivity using an ion beam sputtering system (KUR-IBS), as well as all neutron supermirrors in two neutron guide tubes at BL06 at J-PARC/MLF. We also realized a large flexible self-standing m=5 NiC/Ti supermirror and very small d-spacing (d=1.65 nm) multilayer sheets. In this paper, we present an overview of the performance and utility of non-magnetic neutron multilayer mirrors fabricated with the KUR-IBS

  13. Advanced Environmental Barrier Coatings Developed for SiC/SiC Composite Vanes

    NASA Technical Reports Server (NTRS)

    Lee, Kang N.; Fox, Dennis S.; Eldridge, Jeffrey I.; Zhu, Dongming; Bansal, Narottam P.; Miller, Robert A.

    2003-01-01

    Ceramic components exhibit superior high-temperature strength and durability over conventional component materials in use today, signifying the potential to revolutionize gas turbine engine component technology. Silicon-carbide fiber-reinforced silicon carbide ceramic matrix composites (SiC/SiC CMCs) are prime candidates for the ceramic hotsection components of next-generation gas turbine engines. A key barrier to the realization of SiC/SiC CMC hot-section components is the environmental degradation of SiC/SiC CMCs in combustion environments. This is in the form of surface recession due to the volatilization of silica scale by water vapor. An external environmental barrier coating (EBC) is a logical approach to achieve protection and long-term durability.

  14. Corals Like It Waxed: Paraffin-Based Antifouling Technology Enhances Coral Spat Survival

    PubMed Central

    Tebben, Jan; Guest, James R.; Sin, Tsai M.; Steinberg, Peter D.; Harder, Tilmann

    2014-01-01

    The early post-settlement stage is the most sensitive during the life history of reef building corals. However, few studies have examined the factors that influence coral mortality during this period. Here, the impact of fouling on the survival of newly settled coral spat of Acropora millepora was investigated by manipulating the extent of fouling cover on settlement tiles using non-toxic, wax antifouling coatings. Survival of spat on coated tiles was double that on control tiles. Moreover, there was a significant negative correlation between percentage cover of fouling and spat survival across all tiles types, suggesting that fouling in direct proximity to settled corals has detrimental effects on early post-settlement survival. While previous studies have shown that increased fouling negatively affects coral larval settlement and health of juvenile and adult corals, to the best of our knowledge, this is the first study to show a direct relationship between fouling and early post-settlement survival for a broadcast spawning scleractinian coral. The negative effects of fouling on this sensitive life history stage may become more pronounced in the future as coastal eutrophication increases. Our results further suggest that targeted seeding of coral spat on artificial surfaces in combination with fouling control could prove useful to improve the efficiency of sexual reproduction-based coral propagation for reef rehabilitation. PMID:24489936

  15. Probing nanoscale chemical segregation and surface properties of antifouling hybrid xerogel films.

    PubMed

    Destino, Joel F; Gatley, Caitlyn M; Craft, Andrew K; Detty, Michael R; Bright, Frank V

    2015-03-24

    Over the past decade there has been significant development in hybrid polymer coatings exhibiting tunable surface morphology, surface charge, and chemical segregation-all believed to be key properties in antifouling (AF) coating performance. While a large body of research exists on these materials, there have yet to be studies on all the aforementioned properties in a colocalized manner with nanoscale spatial resolution. Here, we report colocalized atomic force microscopy, scanning Kelvin probe microscopy, and confocal Raman microscopy on a model AF xerogel film composed of 1:9:9 (mol:mol:mol) 3-aminopropyltriethoxysilane (APTES), n-octyltriethoxysilane (C8), and tetraethoxysilane (TEOS) formed on Al2O3. This AF film is found to consist of three regions that are chemically and physically unique in 2D and 3D across multiple length scales: (i) a 1.5 μm thick base layer derived from all three precursors; (ii) 2-4 μm diameter mesa-like features that are enriched in free amine (from APTES), depleted in the other species and that extend 150-400 nm above the base layer; and (iii) 1-2 μm diameter subsurface inclusions within the base layer that are enriched in hydrogen-bonded amine (from APTES) and depleted in the other species.

  16. Nanostructured Block Copolymer Coatings for Biofouling Inhibition

    DTIC Science & Technology

    2015-06-30

    despite similar contact angles) indicating that the amphiphilic nature and patterning of the coating was deterring spore settlement . The two PS-P2VP-PEO...involved settlement and release of algal spores/sporelings, barnacle cyprids/adults, and tubeworm adults, against these phase segregated block...Our previous studies investigated the antifouling properties of a triblock copolymer system PS-b-P2VP-b- PEO in the field in Florida. No settlement of

  17. Zwitteration: Coating Surfaces with Zwitterionic Functionality to Reduce Nonspecific Adsorption

    PubMed Central

    2015-01-01

    Coating surfaces with thin or thick films of zwitterionic material is an effective way to reduce or eliminate nonspecific adsorption to the solid/liquid interface. This review tracks the various approaches to zwitteration, such as monolayer assemblies and polymeric brush coatings, on micro- to macroscopic surfaces. A critical summary of the mechanisms responsible for antifouling shows how zwitterions are ideally suited to this task. PMID:24754399

  18. Conductive Polymer-Coated VS4 Submicrospheres As Advanced Electrode Materials in Lithium-Ion Batteries.

    PubMed

    Zhou, Yanli; Li, Yanlu; Yang, Jing; Tian, Jian; Xu, Huayun; Yang, Jian; Fan, Weiliu

    2016-07-27

    VS4 as an electrode material in lithium-ion batteries holds intriguing features like high content of sulfur and one-dimensional structure, inspiring the exploration in this field. Herein, VS4 submicrospheres have been synthesized via a simple solvothermal reaction. However, they quickly degrade upon cycling as an anode material in lithium-ion batteries. So, three conductive polymers, polythiophene (PEDOT), polypyrrole (PPY), and polyaniline (PANI), are coated on the surface to improve the electron conductivity, suppress the diffusion of polysulfides, and modify the interface between electrode/electrolyte. PANI is the best in the polymers. It improves the Coulombic efficiency to 86% for the first cycle and keeps the specific capacity at 755 mAh g(-1) after 50 cycles, higher than the cases of naked VS4 (100 mAh g(-1)), VS4@PEDOT (318 mAh g(-1)), and VS4@PPY (448 mAh g(-1)). The good performances could be attributed to the improved charge-transfer kinetics and the strong interaction between PANI and VS4 supported by theoretical simulation. The discharge voltage ∼2.0 V makes them promising cathode materials.

  19. Effects of Doping on Thermal Conductivity of Pyrochlore Oxides for Advanced Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Zhu, Dongming; Eslamloo-Grami, Maryam

    2006-01-01

    Pyrochlore oxides of general composition, A2B2O7, where A is a 3(+) cation (La to Lu) and B is a 4(+) cation (Zr, Hf, Ti, etc.) have high melting point, relatively high coefficient of thermal expansion, and low thermal conductivity which make them suitable for applications as high-temperature thermal barrier coatings. The effect of doping at the A site on the thermal conductivity of a pyrochlore oxide La2Zr2O7, has been investigated. Oxide powders of various compositions La2Zr2O7, La(1.7)Gd(0.3)Zr2O7, La(1.7)Yb(0.3)Zr2O7 and La(1.7)Gd(0.15)Yb(0.15)Zr2O7 were synthesized by the citric acid sol-gel method. These powders were hot pressed into discs and used for thermal conductivity measurements using a steady-state laser heat flux test technique. The rare earth oxide doped pyrochlores La(1.7)Gd(0.3)Zr2O7, La(1.7)Yb(0.3)Zr2O7 and La(1.7)Gd(0.15)Yb(0.15)Zr2O7 had lower thermal conductivity than the un-doped La2Zr2O7. The Gd2O3 and Yb2O3 co-doped composition showed the lowest thermal conductivity.

  20. Microstructure characterization of advanced protective Cr/CrN+a-C:H/a-C:H:Cr multilayer coatings on carbon fibre composite (CFC).

    PubMed

    Major, L; Janusz, M; Lackner, J M; Kot, M; Major, B

    2016-06-01

    Studies of advanced protective chromium-based coatings on the carbon fibre composite (CFC) were performed. Multidisciplinary examinations were carried out comprising: microstructure transmission electron microscopy (TEM, HREM) studies, micromechanical analysis and wear resistance. Coatings were prepared using a magnetron sputtering technique with application of high-purity chromium and carbon (graphite) targets deposited on the CFC substrate. Selection of the CFC for surface modification in respect to irregularities on the surface making the CFC surface more smooth was performed. Deposited coatings consisted of two parts. The inner part was responsible for the residual stress compensation and cracking initiation as well as resistance at elevated temperatures occurring namely during surgical tools sterilization process. The outer part was responsible for wear resistance properties and biocompatibility. Experimental studies revealed that irregularities on the substrate surface had a negative influence on the crystallites growth direction. Chromium implanted into the a-C:H structure reacted with carbon forming the cubic nanocrystal chromium carbides of the Cr23 C6 type. The cracking was initiated at the coating/substrate interface and the energy of brittle cracking was reduced because of the plastic deformation at each Cr interlayer interface. The wear mechanism and cracking process was described in micro- and nanoscale by means of transmission electron microscope studies. Examined materials of coated CFC type would find applications in advanced surgical tools.

  1. Evaluation of Anti-fouling Materials for Optical Sensors

    DTIC Science & Technology

    1997-09-30

    Hani R., Waldron C. and Farmer D. A. (1994) Gel-Free Paint Containing Zinc Pyrithione , Cuprous Oxide, and Carboxylic Acid. U.S. Patent 5342437, Olin Corp...2. Hani R., Waldron C. and Farmer D. A. Jr. (1992) Stabilization of Paints Containing Zinc Pyrithione and Cuprous Oxide Antifouling Agents. U.S...using ESEM. The following commercially prepared formulations provided by Magellan Co., Inc. were evaluated: 1) 10,000 ppm zinc pyrithione1,2,3 + 300 ppm

  2. Environmental fate of the antifouling compound zinc pyrithione in seawater.

    PubMed

    Grunnet, Katja S; Dahllöf, Ingela

    2005-12-01

    To perform a thorough risk assessment of the new antifouling compound zinc pyrithione (ZnPT2), additional information regarding the fate of the compound is needed. The present study examined the recovery and transchelation of ZnPT2 in controlled laboratory experiments, photodegradation experiments, and a fate study in a large-scale field experiment. Chemical analyses were performed using a newly developed method for simultaneous analyses of ZnPT2 and copper pyrithione (CuPT2). Furthermore, two antifouling paints containing ZnPT2 were examined for the fate of leaching biocide. Naturally occurring ligands and metals in seawater influence the stability of ZnPT2. The presence of free Cu2+, which is present naturally in the seawater or is released from copper-containing paints, results in a partial transchelation of ZnPT2 into CuPT2. A complete transchelation of ZnPT2 into CuPT2 was observed when Cu2+ was present at an equimolar concentration in the absence of interfering ligands. When ZnPT2 was leached from antifouling paints containing both ZnPT2 and Cu2O, CuPT2 was found, with no trace of ZnPT2. Photodegradation was low in natural waters and absent from 1 m or more below the surface. The results show that ZnPT2 has a low persistence in seawater when leached from antifouling paints. However, the more stable and toxic transchelation product CuPT2 is formed, which has the potential to accumulate in the sediments and, therefore, should be included in both chemical analysis and risk assessment of ZPT2.

  3. Antifouling potential of Nature-inspired sulfated compounds

    PubMed Central

    Almeida, Joana R.; Correia-da-Silva, Marta; Sousa, Emília; Antunes, Jorge; Pinto, Madalena; Vasconcelos, Vitor; Cunha, Isabel

    2017-01-01

    Natural products with a sulfated scaffold have emerged as antifouling agents with low or nontoxic effects to the environment. In this study 13 sulfated polyphenols were synthesized and tested for antifouling potential using the anti-settlement activity of mussel (Mytilus galloprovincialis) plantigrade post-larvae and bacterial growth inhibition towards four biofilm-forming bacterial strains. Results show that some of these Nature-inspired compounds were bioactive, particularly rutin persulfate (2), 3,6-bis(β-D-glucopyranosyl) xanthone persulfate (6), and gallic acid persulfate (12) against the settlement of plantigrades. The chemical precursors of sulfated compounds 2 and 12 were also tested for anti-settlement activity and it was possible to conclude that bioactivity is associated with sulfation. While compound 12 showed the most promising anti-settlement activity (EC50 = 8.95 μg.mL−1), compound 2 also caused the higher level of growth inhibition in bacteria Vibrio harveyi (EC20 = 12.5 μg.mL−1). All the three bioactive compounds 2, 6, and 12 were also found to be nontoxic to the non target species Artemia salina (<10% mortality at 250 μM) and Vibrio fischeri (LC50 > 1000 μg.mL−1). This study put forward the relevance of synthesizing non-natural sulfated small molecules to generate new nontoxic antifouling agents. PMID:28205590

  4. Antifouling potential of Nature-inspired sulfated compounds

    NASA Astrophysics Data System (ADS)

    Almeida, Joana R.; Correia-da-Silva, Marta; Sousa, Emília; Antunes, Jorge; Pinto, Madalena; Vasconcelos, Vitor; Cunha, Isabel

    2017-02-01

    Natural products with a sulfated scaffold have emerged as antifouling agents with low or nontoxic effects to the environment. In this study 13 sulfated polyphenols were synthesized and tested for antifouling potential using the anti-settlement activity of mussel (Mytilus galloprovincialis) plantigrade post-larvae and bacterial growth inhibition towards four biofilm-forming bacterial strains. Results show that some of these Nature-inspired compounds were bioactive, particularly rutin persulfate (2), 3,6-bis(β-D-glucopyranosyl) xanthone persulfate (6), and gallic acid persulfate (12) against the settlement of plantigrades. The chemical precursors of sulfated compounds 2 and 12 were also tested for anti-settlement activity and it was possible to conclude that bioactivity is associated with sulfation. While compound 12 showed the most promising anti-settlement activity (EC50 = 8.95 μg.mL‑1), compound 2 also caused the higher level of growth inhibition in bacteria Vibrio harveyi (EC20 = 12.5 μg.mL‑1). All the three bioactive compounds 2, 6, and 12 were also found to be nontoxic to the non target species Artemia salina (<10% mortality at 250 μM) and Vibrio fischeri (LC50 > 1000 μg.mL‑1). This study put forward the relevance of synthesizing non-natural sulfated small molecules to generate new nontoxic antifouling agents.

  5. Engineered antifouling microtopographies: surface pattern effects on cell distribution.

    PubMed

    Decker, Joseph T; Sheats, Julian T; Brennan, Anthony B

    2014-12-23

    Microtopography has been observed to lead to altered attachment behavior for marine fouling organisms; however, quantification of this phenomenon is lacking in the scientific literature. Here, we present quantitative measurement of the disruption of normal attachment behavior of the fouling algae Ulva linza by antifouling microtopographies. The distribution of the diatom Navicula incerta was shown to be unaffected by the presence of topography. The radial distribution function was calculated for both individual zoospores and cells as well as aggregates of zoospores from attachment data for a variety topographic configurations and at a number of different attachment densities. Additionally, the screening distance and maximum values were mapped according to the location of zoospore aggregates within a single unit cell. We found that engineered topographies decreased the distance between spore aggregates compared to that for a smooth control surface; however, the distributions for individual spores were unchanged. We also found that the local attachment site geometry affected the screening distance for aggregates of zoospores, with certain geometries decreasing screening distance and others having no measurable effect. The distribution mapping techniques developed and explored in this article have yielded important insight into the design parameters for antifouling microtopographies that can be implemented in the next generation of antifouling surfaces.

  6. New biocide-free anti-fouling paints are toxic.

    PubMed

    Karlsson, Jenny; Eklund, Britta

    2004-09-01

    A number of new anti-fouling paints claimed to be more friendly to the environment, have entered the market since prohibition of biocide containing paints have been enforced in many areas. Leakage waters from five new anti-fouling paints were tested for toxic effects to the macro algae Ceramium tenuicorne and Ceramium strictum and to the crustacean Nitocra spinipes. A banned copper and irgarol 1051 containing anti-fouling paint was used as reference. Five of the six paints tested were toxic to all or some of the organisms after two weeks of leakage with EC50 ranging from 0.08 to around 2% leakage water and LC50 ranging from 1.1% to 88%. The toxicity of leakage water from these paints was still high after 16 weeks. We conclude that these paints contain substances toxic to common organisms in the coastal Baltic ecosystem. A silicone based paint did not exhibit toxic effects to the two organisms. We recommend that biological tests should be used to identify the most harmful products before they are released on the market.

  7. Advanced Materials for Aircraft Propulsion Systems. Phase I. Investigation of Corrosion Resistant Coatings for Service at 3000 F and above.

    DTIC Science & Technology

    diffusion barrier between the coating and metallic substrate. Preliminary studies were limited to development of coatings that would be applicable to the protection of Ni-base and Co-base superalloys. (Author)

  8. Material Science for High-Efficiency Photovoltaics: From Advanced Optical Coatings to Cell Design for High-Temperature Applications

    NASA Astrophysics Data System (ADS)

    Perl, Emmett Edward

    Solar cells based on III-V compound semiconductors are ideally suited to convert solar energy into electricity. The highest efficiency single-junction solar cells are made of gallium arsenide, and have attained an efficiency of 28.8%. Multiple III-V materials can be combined to construct multijunction solar cells, which have reached record efficiencies greater than 45% under concentration. III-V solar cells are also well suited to operate efficiently at elevated temperatures, due in large part to their high material quality. These properties make III-V solar cells an excellent choice for use in concentrator systems. Concentrator photovoltaic systems have attained module efficiencies that exceed 40%, and have the potential to reach the lowest levelized cost of electricity in sunny places like the desert southwest. Hybrid photovoltaic-thermal solar energy systems can utilize high-temperature III-V solar cells to simultaneously achieve dispatchability and a high sunlight-to-electricity efficiency. This dissertation explores material science to advance the state of III-V multijunction solar cells for use in concentrator photovoltaic and hybrid photovoltaic-thermal solar energy systems. The first half of this dissertation describes work on advanced optical designs to improve the efficiency of multijunction solar cells. As multijunction solar cells move to configurations with four or more subcells, they utilize a larger portion of the solar spectrum. Broadband antireflection coatings are essential to realizing efficiency gains for these state-of-the-art cells. A hybrid design consisting of antireflective nanostructures placed on top of multilayer interference-based optical coatings is developed. Antireflection coatings that utilize this hybrid approach yield unparalleled performance, minimizing reflection losses to just 0.2% on sapphire and 0.6% on gallium nitride for 300-1800nm light. Dichroic mirrors are developed for bonded 5-junction solar cells that utilize InGaN as

  9. Nanomechanical properties of advanced plasma polymerized coatings for mechanical data storage.

    PubMed

    Tranchida, Davide; Pihan, Sascha A; Zhang, Yi; Schönherr, Holger; Berger, Rüdiger

    2011-04-07

    In this paper we report on the unprecedented deformation behavior of stratified ultrathin polymer films. The mechanical behavior of layered nanoscale films composed of 8-12 nm thin plasma polymerized hexamethyldisiloxane (ppHMDSO) films on a 70 nm thick film of polystyrene was unveiled by atomic force microscopy nanoindentation. In particular, we observed transitions from the deformation of a thin plate under point load to an elastic contact of a paraboloid of revolution, followed by an elastic-plastic contact for polystyrene and finally an elastic contact for silicon. The different deformation modes were identified on the basis of force-penetration data and atomic force microscopy images of residual indents. A clear threshold was observed for the onset of plastic deformation of the films at loads larger than 2 μN. The measured force curves are in agreement with an elastic and elastic-plastic contact mechanics model, taking the amount of deformation and the geometry of the layer that presumably contributed more to the overall deformation into account. This study shows that the complex deformation behavior of advanced soft matter systems with nanoscale dimensions can be successfully unraveled.

  10. Hierarchical micro-lamella-structured 3D porous copper current collector coated with tin for advanced lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Park, Hyeji; Um, Ji Hyun; Choi, Hyelim; Yoon, Won-Sub; Sung, Yung-Eun; Choe, Heeman

    2017-03-01

    A Novel 3D porous Sn-Cu architecture is prepared as an anode material for use in an advanced lithium-ion battery. Micro-lamellar-structured 3D porous Cu foam, which is electroless-plated with Sn as an active material, is used as anode current collector. Compared to Sn-coated Cu foil, the 3D Sn-Cu foam exhibits superior Li-ion capacity and stable capacity retention, demonstrating the advantage of 3D porous architecture by preserving its structural integrity. In addition, the effect of heat-treatment after Sn plating is investigated. Sn/Sn6Cu5 and SnO2/Cu10Sn3 were formed on and in the 3D Sn-Cu foam under the heat-treatment at 150 °C and 500 °C, respectively. The development of Cu10Sn3 in the 3D Sn-Cu foam heat-treated at 500 °C can be a key factor for the enhanced cyclic stability because the Cu10Sn3 inactively reacts with Li-ion and alleviates the volume expansion of SnO2 as an inactive matrix.

  11. Flowerlike CeO2 microspheres coated with Sr2Fe1.5Mo0.5Ox nanoparticles for an advanced fuel cell

    PubMed Central

    Liu, Yanyan; Tang, Yongfu; Ma, Zhaohui; Singh, Manish; He, Yunjuan; Dong, Wenjing; Sun, Chunwen; Zhu, Bin

    2015-01-01

    Flowerlike CeO2 coated with Sr2Fe1.5Mo0.5Ox (Sr-Fe-Mo-oxide) nanoparticles exhibits enhanced conductivity at low temperatures (300–600 oC), e.g. 0.12 S cm−1 at 600 oC, this is comparable to pure ceria (0.1 S cm−1 at 800 oC). Advanced single layer fuel cell was constructed using the flowerlike CeO2/Sr-Fe-Mo-oxide layer attached to a Ni-foam layer coated with the conducting transition metal oxide. Such fuel cell has yielded a peak power density of 802 mWcm−2 at 550 oC. The mechanism of enhanced conductivity and cell performance were analyzed. These results provide a promising strategy for developing advanced low-temperature SOFCs. PMID:26154917

  12. Incorporation of Nicotine into Silicone Coatings for Marine Applications

    NASA Astrophysics Data System (ADS)

    Jaramillo, Sandy Tuyet

    PDMS-based marine coatings presently used are limited by their inability to mitigate microfouling which limits their application to high speed vessels. PDMS coatings are favored when viable, due to their foul release properties of macrofouling organisms. Natural products have been investigated for antifouling properties for potential use in these marine antifouling coatings but few have incorporated natural products into coatings or coating systems. The purpose of the research was to establish the corrosion inhibiting properties of nicotine and to incorporate nicotine, a biodegradable and readily available natural product, into a PDMS coating to demonstrate the use of a natural product in a coating for marine applications. The corrosion inhibiting properties of nicotine was examined using potentiodynamic polarization scans, material characterization techniques such as scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction, quartz crystal microbalance and electrochemical impedance spectroscopy. Nicotine was determined to be an anodic corrosion inhibitor for mild steel immersed in simulated seawater with the ability to precipitate a protective calcium carbonate film. Electrochemical impedance spectroscopy was used to evaluate the performance of the developed nicotine incorporated coatings on mild steel immersed in simulated seawater over 21 days of immersion. The coatings with 2 wt.% of nicotine incorporated in the coating with a ratio of 1:30 of additional platinum catalyst to nicotine exhibited the best performance for intact coatings. This coating had the most favorable balance of the amount of nicotine and platinum catalyst of all the coatings evaluated. Overall, all nicotine incorporated coatings had a performance improvement when compared to the control PDMS coating. Of the nicotine incorporated coatings that were tested with an artificial pin-hole defect, the 2PDMS coating also exhibited the best performance with significant

  13. Advanced thermal barrier system bond coatings for use on Ni, Co-, and Fe-base alloy substrates

    NASA Technical Reports Server (NTRS)

    Stecura, S.

    1985-01-01

    New and improved Ni-, Co-, and Fe-base bond coatings have been identified for the ZrO2-Y2O3 thermal barrier coatings to be used on NI-, Co-, and Fe-base alloy substrates. These bond coatings were evaluated in a cyclic furnace between 1120 and 1175 C. It was found that MCrAlYb (where M = Ni, Co, or Fe) bond coating thermal barrier systems. The longest life was obtained with the FeCrAlYb thermal barrier system followed by NiCrAlYb and CoCrAlYb thermal barrier systems in that order.

  14. Antifouling Activity of Synthetic Alkylpyridinium Polymers Using the Barnacle Model

    PubMed Central

    Piazza, Veronica; Dragić, Ivanka; Sepčić, Kristina; Faimali, Marco; Garaventa, Francesca; Turk, Tom; Berne, Sabina

    2014-01-01

    Polymeric alkylpyridinium salts (poly-APS) isolated from the Mediterranean marine sponge, Haliclona (Rhizoniera) sarai, effectively inhibit barnacle larva settlement and natural marine biofilm formation through a non-toxic and reversible mechanism. Potential use of poly-APS-like compounds as antifouling agents led to the chemical synthesis of monomeric and oligomeric 3-alkylpyridinium analogues. However, these are less efficient in settlement assays and have greater toxicity than the natural polymers. Recently, a new chemical synthesis method enabled the production of poly-APS analogues with antibacterial, antifungal and anti-acetylcholinesterase activities. The present study examines the antifouling properties and toxicity of six of these synthetic poly-APS using the barnacle (Amphibalanus amphitrite) as a model (cyprids and II stage nauplii larvae) in settlement, acute and sub-acute toxicity assays. Two compounds, APS8 and APS12-3, show antifouling effects very similar to natural poly-APS, with an anti-settlement effective concentration that inhibits 50% of the cyprid population settlement (EC50) after 24 h of 0.32 mg/L and 0.89 mg/L, respectively. The toxicity of APS8 is negligible, while APS12-3 is three-fold more toxic (24-h LC50: nauplii, 11.60 mg/L; cyprids, 61.13 mg/L) than natural poly-APS. This toxicity of APS12-3 towards nauplii is, however, 60-fold and 1200-fold lower than that of the common co-biocides, Zn- and Cu-pyrithione, respectively. Additionally, exposure to APS12-3 for 24 and 48 h inhibits the naupliar swimming ability with respective IC50 of 4.83 and 1.86 mg/L. PMID:24699112

  15. Various mortars for anti-fouling purposes in marine environments

    SciTech Connect

    Kanematsu, Hideyuki; Masuda, Tomoka; Miura, Yoko; Kuroda, Daisuke; Hirai, Nobumitsu; Yokoyama, Seiji

    2014-02-20

    The antifouling properties for some mortars with steel making slags were investigated by real marine immersion tests and a unique laboratory acceleration tests with a specially devised biofilm acceleration reactors. Mortars mixed with steel making slags containing abundant iron elements tended to form biofilm and also bifouling. The two kinds of biofilm formation tests were used in this study. Real immersion in marine environments and laboratory test with a specially devised biofilm acceleration reactor. The former evaluated the biofouling characteristics more properly, while the latter did the biofilm formation characteristics more effectively.

  16. Various mortars for anti-fouling purposes in marine environments

    NASA Astrophysics Data System (ADS)

    Kanematsu, Hideyuki; Masuda, Tomoka; Miura, Yoko; Hirai, Nobumitsu; Kuroda, Daisuke; Yokoyama, Seiji

    2014-02-01

    The antifouling properties for some mortars with steel making slags were investigated by real marine immersion tests and a unique laboratory acceleration tests with a specially devised biofilm acceleration reactors. Mortars mixed with steel making slags containing abundant iron elements tended to form biofilm and also bifouling. The two kinds of biofilm formation tests were used in this study. Real immersion in marine environments and laboratory test with a specially devised biofilm acceleration reactor. The former evaluated the biofouling characteristics more properly, while the latter did the biofilm formation characteristics more effectively.

  17. A new simple method with high precision for determining the toxicity of antifouling paints on brine shrimp larvae (Artemia): first results.

    PubMed

    Castritsi-Catharios, J; Bourdaniotis, N; Persoone, G

    2007-04-01

    The use of antifouling paints is the only truly effective method for the protection of underwater structures from the development of fouling organisms. In the present study, the surface to volume concept constitutes the basis for the development of a new and improved method for determining the toxicity of antifouling paints on marine organisms. Particular emphasis is placed on the attainment of a standardized uniformity of coated surfaces. Failure to control the thickness of the coat of paint in previous studies of this type, has led to inaccurate evaluation of the relative toxicity of samples. Herein, an attempt is made to solve this problem using a simple technique which gives completely uniform and smooth surfaces. The effectiveness of this technique is assessed through two series of experiments using two different types of test containers: 50 ml modified syringes and 7 ml multiwells. The results of the toxicity experiments follow a normal distribution around the average value which allows to consider these values as reliable for comparison of the level of toxic effect detected with the two types of test containers. The mean lethal concentration L(S/V)(50) in the test series conducted in the multiwells (20.38 mm(2)ml(-1)) does not differ significantly from that obtained in the test series using modified syringes (20.065 mm(2)ml(-1)). It can thus be concluded from this preliminary study that the new method and the two different ways of exposing the test organisms to the antifouling paints and their leachates gave reliable and replicable results.

  18. Investigation of PACVD protective coating processes using advanced diagnostics techniques. Performance report, 1 September 1992--30 April 1993

    SciTech Connect

    Roman, W.C.

    1993-05-07

    Objective is to understand the mechanisms governing nonequilibrium plasma atomistic or molecular deposition of hard face coatings. Laser diagnostic methods include coherent anti-Stokes Raman spectroscopy (CARS) and laser-induced fluorescence. TiB{sub 2} and diamonds were used as the hard face coating materials. Diborane was used as precursor to TiB{sub 2}.

  19. Advanced turbine systems - research and development of thermal barrier coatings technology: 3rd bimonthly report, April 1996

    SciTech Connect

    1996-04-01

    Objective of the ATS program is the development of ultra-highly efficient, environmentally superior, and cost-competitive gas turbine systems, using thermal barrier coatings. These coatings should be stable in the thermal and corrosive environments of the industrial engine for up to 2500 hours. Phase II (development) is current.

  20. Advanced thermal barrier system bond coatings for use on nickel-, cobalt- and iron-base alloy substrates

    NASA Technical Reports Server (NTRS)

    Stecura, S.

    1986-01-01

    New and improved Ni-, Co-, and Fe-base bond coatings have been identified for the ZrO2-Y2O3 thermal barrier coatings to be used on Ni-, Co-, and Fe-base alloy substrates. These bond coatings were evaluated in a cyclic furnace between 1120 and 1175 C. It was found that MCrAlYb (where M = Ni, Co, or Fe) bond coating thermal barrier systems have significantly longer lives than MCrAlY bond coating thermal barrier systems. The longest life was obtained with the FeCrAlYb thermal barrier system followed by NiCrAlYb and CoCrAlYb thermal barrier systems in that order.

  1. Multifunctional copolymer coating of polyethylene glycol, glycidyl methacrylate, and REDV to enhance the selectivity of endothelial cells.

    PubMed

    Wei, Yu; Zhang, Jingxun; Li, Haolie; Zhang, Li; Bi, Hong

    2015-01-01

    Multifunctional polymer coatings have potential applications in biomaterials. These coatings possess reactive functional groups for the immobilization of specific biological factors that can influence cellular behavior. These coatings also display low nonspecific protein adsorption. In this study, we prepared a multifunctional polymer coating through the deposition of random copolymers of poly(ethylene glycol) methacrylate (PEGMA) and glycidyl methacrylate (GMA) to prevent nonspecific attachment and enable the covalence of Arg-Glu-Asp-Val (REDV) peptide with endothelial cells (ECs) selectivity. Coatings were characterized by X-ray photoelectron spectroscopy (XPS). The adhesion and proliferation of ECs and smooth muscle cells (SMCs) onto the REDV-modified surface were investigated to understand the synergistic action of antifouling PEG and EC selective REDV peptide conjugated GMA. The copolymers containing GMA and PEG groups are very useful as a multifunctional coating material with anti-fouling and ECs specific adhesion for implant materials surface modification.

  2. Antifouling potentials of eight deep-sea-derived fungi from the South China Sea.

    PubMed

    Zhang, Xiao-Yong; Xu, Xin-Ya; Peng, Jiang; Ma, Chun-Feng; Nong, Xu-Hua; Bao, Jie; Zhang, Guang-Zhao; Qi, Shu-Hua

    2014-04-01

    Marine-derived microbial secondary metabolites are promising potential sources of nontoxic antifouling agents. The search for environmentally friendly and low-toxic antifouling components guided us to investigate the antifouling potentials of eight novel fungal isolates from deep-sea sediments of the South China Sea. Sixteen crude ethyl acetate extracts of the eight fungal isolates showed distinct antibacterial activity against three marine bacteria (Loktanella hongkongensis UST950701-009, Micrococcus luteus UST950701-006 and Pseudoalteromonas piscida UST010620-005), or significant antilarval activity against larval settlement of bryozoan Bugula neritina. Furthermore, the extract of Aspergillus westerdijkiae DFFSCS013 displayed strong antifouling activity in a field trial lasting 4 months. By further bioassay-guided isolation, five antifouling alkaloids including brevianamide F, circumdatin F and L, notoamide C, and 5-chlorosclerotiamide were isolated from the extract of A. westerdijkiae DFFSCS013. This is the first report about the antifouling potentials of metabolites of the deep-sea-derived fungi from the South China Sea, and the first stage towards the development of non- or low-toxic antifouling agents from deep-sea-derived fungi.

  3. Developing antifouling biointerfaces based on bioinspired zwitterionic dopamine through pH-modulated assembly.

    PubMed

    Huang, Chun-Jen; Wang, Lin-Chuan; Shyue, Jing-Jong; Chang, Ying-Chih

    2014-10-28

    The use of synthetic biomaterials as implantable devices typically is accompanied by considerable nonspecific adsorption of proteins, cells, and bacteria. These may eventually induce adverse pathogenic problems in clinical practice, such as thrombosis and biomaterial-associated infection. Thus, an effective surface coating for medical devices has been pursued to repel nonspecific adsorption from surfaces. In this study, we employ an adhesive dopamine molecule conjugated with zwitterionic sulfobetaine moiety (SB-DA), developed based on natural mussels, as a surface ligand for the modification of TiO2. The electrochemical study shows that the SB-DA exhibits fully reversible reduction-oxidation behavior at pH 3, but it is irreversible at pH 8. A contact angle goniometer and X-ray photoelectron spectroscopy were utilized to explore the surface hydration, chemical states, and bonding mechanism of SB-DA. The results indicate that the binding between hydroxyl groups of SB-DA and TiO2 converts from hydrogen bonds to bidentate binding upon the pH transition from pH 3 to 8. In order to examine the antifouling properties of SB-DA thin films, the modified substrates were brought into contact with bovine serum albumin and bacteria solutions. The fouling levels were monitored using a quartz crystal microbalance with dissipation sensor and fluorescence optical microscope. Tests showed that the sample prepared via the pH transition approach provides the best resistance to nonspecific adsorption due to the high coverage and stability of the SB-DA films. These findings support the mechanism of the pH-modulated assembly of SB-DA molecules, and for the first time we demonstrate the antifouling properties of the SB-DA to be comparable with traditional thiol-based zwitterionic self-assemblies. The success of modification with SB-DA opens an avenue for developing a biologically inspired surface chemistry and can have applications over a wide spectrum of bioapplications. The strategy of

  4. Tuning the underwater oleophobicity of graphene oxide coatings via UV irradiation.

    PubMed

    Li, Hang; Huang, Yi; Mao, Yating; Xu, Weiwei L; Ploehn, Harry J; Yu, Miao

    2014-09-07

    Ultraviolet (UV) irradiation was utilized to gradually modify the chemistry and structure of graphene oxide (GO) flakes, as confirmed by XPS and AFM. Ultrathin GO coatings/membranes, made of UV-irradiated flakes, showed tunable underwater oleophobicity. UV-treated, superoleophobic GO membranes exhibited excellent antifouling capability for oil/water separation.

  5. A Study of Advanced Materials for Gas Turbine Coatings at Elevated Temperatures Using Selected Microstructures and Characteristic Environments for Syngas Combustion

    SciTech Connect

    Ravinder Diwan; Patrick Mensah; Guoqiang Li; Nalini Uppu; Strphen Akwaboa; Monica Silva; Ebubekir Beyazoglu; Ogad Agu; Naresh Polasa; Lawrence Bazille; Douglas Wolfe; Purush Sahoo

    2011-02-10

    Thermal barrier coatings (TBCs) that can be suitable for use in industrial gas turbine engines have been processed and compared with electron beam physical vapor deposition (EBPVD) microstructures for applications in advanced gas turbines that use coal-derived synthesis gas. Thermo-physical properties have been evaluated of the processed air plasma sprayed TBCs with standard APS-STD and vertically cracked APS-VC coatings samples up to 1300 C. Porosity of these selected coatings with related microstructural effects have been analyzed in this study. Wet and dry thermal cycling studies at 1125 C and spalling resistance thermal cycling studies to 1200 C have also been carried out. Type I and Type II hot corrosion tests were carried out to investigate the effects of microstructure variations and additions of alumina in YSZ top coats in multi-layered TBC structures. The thermal modeling of turbine blade has also been carried out that gives the capability to predict in-service performance temperature gradients. In addition to isothermal high temperature oxidation kinetics analysis in YSZ thermal barrier coatings of NiCoCrAlY bond coats with 0.25% Hf. This can affect the failure behavior depending on the control of the thermally grown oxide (TGO) growth at the interface. The TGO growth kinetics is seen to be parabolic and the activation energies correspond to interfacial growth kinetics that is controlled by the diffusion of O{sub 2} in Al{sub 2}O{sub 3}. The difference between oxidation behavior of the VC and STD structures are attributed to the effects of microstructure morphology and porosity on oxygen ingression into the zirconia and TGO layers. The isothermal oxidation resistance of the STD and VC microstructures is similar at temperatures up to 1200 C. However, the generally thicker TGO layer thicknesses and the slightly faster oxidation rates in the VC microstructures are attributed to the increased ingression of oxygen through the grain boundaries of the vertically

  6. Advanced Multifunctional Coating

    DTIC Science & Technology

    2011-08-17

    McChord AFB – Ranie Feiock, Corrosion Control Program Manager and TSgt Anthony Nowak, Assistant Corrosion Control Program Manager were main POC’s • P...Kessler C-17 Mission Systems Program Manager, DAF Mobility Directorate (937) 656-5340 or DSN 986-5340 Kenneth.Kessler@wpafb.af.mil Ranie

  7. Exploitation of marine algae: biogenic compounds for potential antifouling applications.

    PubMed

    Bhadury, Punyasloke; Wright, Phillip C

    2004-08-01

    Marine algae are one of the largest producers of biomass in the marine environment. They produce a wide variety of chemically active metabolites in their surroundings, potentially as an aid to protect themselves against other settling organisms. These active metabolites, also known as biogenic compounds, produced by several species of marine macro- and micro-algae, have antibacterial, antialgal, antimacrofouling and antifungal properties, which are effective in the prevention of biofouling, and have other likely uses, e.g. in therapeutics. The isolated substances with potent antifouling activity belong to groups of fatty acids, lipopeptides, amides, alkaloids, terpenoids, lactones, pyrroles and steroids. These biogenic compounds have the potential to be produced commercially using metabolic engineering techniques. Therefore, isolation of biogenic compounds and determination of their structure could provide leads for future development of, for example, environmentally friendly antifouling paints. This paper mainly discusses the successes of such research, and the future applications in the context of understanding the systems biology of micro-algae and cyanobacteria.

  8. Bio-inspired strategies for designing antifouling biomaterials.

    PubMed

    Damodaran, Vinod B; Murthy, N Sanjeeva

    2016-01-01

    Contamination of biomedical devices in a biological medium, biofouling, is a major cause of infection and is entirely avoidable. This mini-review will coherently present the broad range of antifouling strategies, germicidal, preventive and cleaning using one or more of biological, chemical and physical techniques. These techniques will be discussed from the point of view of their ability to inhibit protein adsorption, usually the first step that eventually leads to fouling. Many of these approaches draw their inspiration from nature, such as emulating the nitric oxide production in endothelium, use of peptoids that mimic protein repellant peptides, zwitterionic functionalities found in membrane structures, and catechol functionalities used by mussel to immobilize poly(ethylene glycol) (PEG). More intriguing are the physical modifications, creation of micropatterns on the surface to control the hydration layer, making them either superhydrophobic or superhydrophilic. This has led to technologies that emulate the texture of shark skin, and the superhyprophobicity of self-cleaning textures found in lotus leaves. The mechanism of antifouling in each of these methods is described, and implementation of these ideas is illustrated with examples in a way that could be adapted to prevent infection in medical devices.

  9. Searching for “Environmentally-Benign” Antifouling Biocides

    PubMed Central

    Cui, Yan Ting; Teo, Serena L. M.; Leong, Wai; Chai, Christina L. L.

    2014-01-01

    As the result of the ecological impacts from the use of tributyltins (TBT) in shipping, environmental legislation for the registration of chemicals for use in the environment has grown to a monumental challenge requiring product dossiers to include information on the environmental fate and behavior of any chemicals. Specifically, persistence, bioaccumulation and toxicity, collectively known as PBT, are properties of concern in the assessment of chemicals. However, existing measurements of PBT properties are a cumbersome and expensive process, and thus not applied in the early stages of the product discovery and development. Inexpensive methods for preliminary PBT screening would minimize risks arising with the subsequent registration of products. In this article, we evaluated the PBT properties of compounds reported to possess anti-fouling properties using QSAR (quantitative structure-activity relationship) prediction programs such as BIOWIN™ (a biodegradation probability program), KOWWIN™ (log octanol-water partition coefficient calculation program) and ECOSAR™ (Ecological Structure Activity Relationship Programme). The analyses identified some small (Mr < 400) synthetic and natural products as potential candidates for environmentally benign biocides. We aim to demonstrate that while these methods of estimation have limitations, when applied with discretion, they are powerful tools useful in the early stages of research for compound selection for further development as anti-foulants. PMID:24865489

  10. Efficacy of different antifouling treatments for seawater cooling systems.

    PubMed

    López-Galindo, Cristina; Casanueva, José F; Nebot, Enrique

    2010-11-01

    In an industrial seawater cooling system, the effects of three different antifouling treatments, viz. sodium hypochlorite (NaClO), aliphatic amines (Mexel®432) and UV radiation, on the characteristics of the fouling formed were evaluated. For this study a portable pilot plant, as a side-stream monitoring system and seawater cooling system, was employed. The pilot plant simulated a power plant steam condenser, having four titanium tubes under different treatment patterns, where fouling progression could be monitored. The nature of the fouling obtained was chiefly inorganic, showing a clear dependence on the antifouling treatment employed. After 72 days the tubes under treatment showed a reduction in the heat transfer resistance (R) of around 70% for NaClO, 48% for aliphatic amines and 55% for UV, with respect to the untreated tube. The use of a logistic model was very useful for predicting the fouling progression and the maximum asymptotic value of the increment in the heat transfer resistance (ΔR(max)). The apparent thermal conductivity (λ) of the fouling layer showed a direct relationship with the percentage of organic matter in the collected fouling. The characteristics and mode of action of the different treatments used led to fouling with diverse physicochemical properties.

  11. Corrosion resistant coatings. (Latest citations from the EI compendex*plus database). Published Search

    SciTech Connect

    1995-01-01

    The bibliography contains citations concerning the anticorrosive behavior of protective coatings based on such materials as ceramics, metals, and polymers. Topics include high and low temperature corrosion, surface structure, mechanical and chemical properties, applications, and performance evaluations. Paints and powder coatings, and methods of application are also considered. Protective coatings for specific applications such as gas turbines, coal gasification, power plants, papermaking, carbon steels, reinforced concrete, pipelines, antifouling coatings, and conversion coatings are examined in separate bibliographies. (Contains 250 citations and includes a subject term index and title list.)

  12. Application of ICH Q9 Quality Risk Management Tools for Advanced Development of Hot Melt Coated Multiparticulate Systems.

    PubMed

    Stocker, Elena; Becker, Karin; Hate, Siddhi; Hohl, Roland; Schiemenz, Wolfgang; Sacher, Stephan; Zimmer, Andreas; Salar-Behzadi, Sharareh

    2017-01-01

    This study aimed to apply quality risk management based on the The International Conference on Harmonisation guideline Q9 for the early development stage of hot melt coated multiparticulate systems for oral administration. N-acetylcysteine crystals were coated with a formulation composing tripalmitin and polysorbate 65. The critical quality attributes (CQAs) were initially prioritized using failure mode and effects analysis. The CQAs of the coated material were defined as particle size, taste-masking efficiency, and immediate release profile. The hot melt coated process was characterized via a flowchart, based on the identified potential critical process parameters (CPPs) and their impact on the CQAs. These CPPs were prioritized using a process failure mode, effects, and criticality analysis and their critical impact on the CQAs was experimentally confirmed using a statistical design of experiments. Spray rate, atomization air pressure, and air flow rate were identified as CPPs. Coating amount and content of polysorbate 65 in the coating formulation were identified as critical material attributes. A hazard and critical control points analysis was applied to define control strategies at the critical process points. A fault tree analysis evaluated causes for potential process failures. We successfully demonstrated that a standardized quality risk management approach optimizes the product development sustainability and supports the regulatory aspects.

  13. Development of the initial diatom microfouling layer on antifouling and fouling-release surfaces in temperate and tropical Australia.

    PubMed

    Molino, Paul J; Campbell, Ewan; Wetherbee, Richard

    2009-11-01

    Diatoms are a major component of the slime layers that form on artificial surfaces in marine environments. In this article, the role played by diatoms during the pioneering stages of colonization of three marine antifouling (AF) coatings, viz Intersmooth 360, Super Yacht 800 and a fouling-release (FR) coating Intersleek 700, was investigated. The study was conducted over three distinct seasons in two very different marine environments in Australia, ie temperate Williamstown, Victoria and tropical Cairns, Queensland. Diatom fouling occurred more rapidly on the FR coating Intersleek 700, compared to both biocidal AF paints. However, colonization by diatoms on all three coatings was generally slow during the 16-day study. Benthic diatoms do not subsist by floating around in the water column, rather they only gain the opportunity to colonize new surfaces when they either voluntarily release or are displaced from their benthic habitat, thereafter entering the water column where the opportunity to adhere to a new surface presents itself. However, once settled, fouling diatoms grow exponentially from the site of attachment, spreading out until they populate large areas of the surface. This mode of surface colonization correlates more with an 'infection' type, epidemiology model, a mechanism that accounts for the colonization of significant regions of the coating surface from a single fouling diatom cell, forming 'clonal patches'. This is in comparison to the bacterial colonization of the surface, which exhibits far more rapid recruitment and growth of cells on the substratum surface. Therefore, it is hypothesized that fouling diatoms may be characterized more by their ability to adhere and grow on surfaces already modified by bacterial biofilms, rather than on their strength of adhesion. Cell morphology and the ability to avoid shear may also be an important factor.

  14. Phylogenetic relationship and antifouling activity of bacterial epiphytes from the marine alga Ulva lactuca.

    PubMed

    Egan, S; Thomas, T; Holmström, C; Kjelleberg, S

    2000-06-01

    It is widely accepted that bacterial epiphytes can inhibit the colonization of surfaces by common fouling organisms. However, little information is available regarding the diversity and properties of these antifouling bacteria. This study assessed the antifouling traits of five epiphytes of the common green alga, Ulva lactuca. All isolates were capable of preventing the settlement of invertebrate larvae and germination of algal spores. Three of the isolates also inhibited the growth of a variety of bacteria and fungi. Their phylogenetic positions were determined by 16S ribosomal subunit DNA sequencing. All isolates showed a close affiliation with the genus Pseudoalteromonas and, in particular, with the species P. tunicata. Strains of this bacterial species also display a variety of antifouling activities, suggesting that antifouling ability may be an important trait for members of this genus to be highly successful colonizers of animate surfaces and for such species to protect their host against fouling.

  15. An anti-fouling aptasensor for detection of thrombin by dual polarization interferometry.

    PubMed

    Zheng, Yu; Hu, Tao; Chen, Chuanxia; Yang, Fan; Yang, Xiurong

    2015-04-04

    An anti-fouling surface was designed to effectively resist nonspecific protein adsorption using dual polarization interferometry, based on which the aptasensor for detection of thrombin was fabricated according to the specific interaction between thrombin and its 15-mer aptamer.

  16. Anti-fouling properties of microstructured surfaces bio-inspired by rice leaves and butterfly wings.

    PubMed

    Bixler, Gregory D; Theiss, Andrew; Bhushan, Bharat; Lee, Stephen C

    2014-04-01

    Material scientists often look to biology for new engineering solutions to materials science problems. For example, unique surface characteristics of rice leaves and butterfly wings combine the shark skin (antifouling) and lotus leaf (self-cleaning) effects, producing the so-called rice and butterfly wing effect. In this paper, we study antifouling properties of four microstructured surfaces inspired by rice leaves and fabricated with photolithography and hot embossing techniques. Anti-biofouling effectiveness is determined with bioassays using Escherichia coli whilst inorganic fouling with simulated dirt particles. Antifouling data are presented to understand the role of surface geometrical features resistance to fouling. Conceptual modeling provides design guidance when developing novel antifouling surfaces for applications in the medical, marine, and industrial fields.

  17. Diamond Coatings

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Advances in materials technology have demonstrated that it is possible to get the advantages of diamond in a number of applications without the cost penalty, by coating and chemically bonding an inexpensive substrate with a thin film of diamond-like carbon (DLC). Diamond films offer tremendous technical and economic potential in such advances as chemically inert protective coatings; machine tools and parts capable of resisting wear 10 times longer; ball bearings and metal cutting tools; a broad variety of optical instruments and systems; and consumer products. Among the American companies engaged in DLC commercialization is Diamonex, Inc., a diamond coating spinoff of Air Products and Chemicals, Inc. Along with its own proprietary technology for both polycrystalline diamond and DLC coatings, Diamonex is using, under an exclusive license, NASA technology for depositing DLC on a substrate. Diamonex is developing, and offering commercially, under the trade name Diamond Aegis, a line of polycrystalline diamond-coated products that can be custom tailored for optical, electronic and engineering applications. Diamonex's initial focus is on optical products and the first commercial product is expected in late 1990. Other target applications include electronic heat sink substrates, x-ray lithography masks, metal cutting tools and bearings.

  18. Identification of a new degradation product of the antifouling agent Irgarol 1051 in natural samples

    USGS Publications Warehouse

    Ferrer, I.; Barcelo, D.

    2001-01-01

    A main degradation product of Irgarol [2-(methylthio)-4-(tert-butylamino)-6-(cyclopropylamino)-s-triazine], one of the most widely used compounds in antifouling paints, was detected at trace levels in seawater and sediment samples collected from several marinas on the Mediterranean coast. This degradation product was identified as 2-methylthio-4-tert-butylamino-s-triazine. The unequivocal identification of this compound in seawater samples was carried out by solid-phase extraction (SPE) coupled on-line with liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS). SPE was carried out by passing 150 ml of seawater sample through a cartridge containing a polymeric phase (PLRP-s), with recoveries ranging from 92 to 108% (n=5). Using LC-MS detection in positive ion mode, useful structural information was obtained by increasing the fragmentor voltage, thus permitting the unequivocal identification of this compound in natural samples. Method detection limits were in the range of 0.002 to 0.005 ??g/l. Overall, the combination of on-line SPE and LC-APCI-MS represents an important advance in environmental analysis of herbicide degradation products in seawater, since it demonstrates that trace amounts of new polar metabolites may be determined rapidly. This paper reports the LC-MS identification of the main degradation product of Irgarol in seawater and sediment samples. ?? 2001 Elsevier Science B.V. All rights reserved.

  19. Injectable Self-Healing Hydrogel with Antimicrobial and Antifouling Properties.

    PubMed

    Li, Lin; Yan, Bin; Yang, Jingqi; Huang, Weijuan; Chen, Lingyun; Zeng, Hongbo

    2017-03-22

    Microbial adhesion, biofilm formation and associated microbial infection are common challenges faced by implanted biomaterials (e.g., hydrogels) in bioengineering applications. In this work, an injectable self-healing hydrogel with antimicrobial and antifouling properties was prepared through self-assembly of an ABA triblock copolymer employing catechol functionalized polyethylene glycol (PEG) as A block and poly{[2-(methacryloyloxy)-ethyl] trimethylammonium iodide}(PMETA) as B block. This hydrogel exhibits excellent thermosensitivity, and can effectively inhibit the growth of E. coli (>99.8% killing efficiency) and prevent cell attachment. It can also heal autonomously from repeated damage, through mussel-inspired catechol-mediated hydrogen bonding and aromatic interactions, exhibiting great potential in bioengineering applications.

  20. Advances in microreaction technology for portable fuel cell applications: Wall coating of thin catalytic films in microreactors

    NASA Astrophysics Data System (ADS)

    Bravo Bersano, Jaime Cristian

    This research has focused on the need to coat microreactor systems composed of channels in the micron size range of 100 to 1000 mum. The experimental procedures and learning are outlined in terms of slurry and surface preparation requirements which are detailed in the experimental section. This system is motivated and applied to micro methanol steam reformers. Thus, a detailed discussion on the driving motivation is given in the introduction. The low temperatures required for steam-reforming of methanol ˜ 493°K (220°C) make it possible to utilize the reformate as a feed to the fuel cell anode. The group of catalysts that shows the highest activity for methanol steam reforming (SR) at low temperature has composition of CuO/ZnO/Al 2O3, which is also the catalyst used for methanol synthesis. Steam reforming of methanol is a highly endothermic process. Conventional reactor configurations, such as a packed bed reactor, operate in a heat transfer limited mode for this reaction. Using catalyst in packed bed form for portable devices is also not convenient due to high pressure drop and possible channeling of gases in addition to poor heat transfer. A wall-coated catalyst represents a superior geometry since it provides lower pressure drop and ease of manufacturing. Due to their small size, microreactors are especially suited for endothermic reactions whose reactivity depends on the rate of heat input. A brief review on microreaction technology is given with a comprehensive survey for catalyst integration into microreactors for catalytic heterogeneous gas phase reactions. The strength of this research is the model that was developed to coat the interior of micron sized capillaries with coats of CuO/ZnO/Al2O 3 slurries as thick as 25 mum in the dry state. The details of the model are given in terms Taylor's theory and Rayleigh's theory. A model is presented that can predict the coat thickness based on experimental conditions The model combines Taylor's experimental work

  1. Advanced zirconia-coated carbonyl-iron particles for acidic magnetorheological finishing of chemical-vapor-deposited ZnS and other IR materials

    NASA Astrophysics Data System (ADS)

    Salzman, S.; Giannechini, L. J.; Romanofsky, H. J.; Golini, N.; Taylor, B.; Jacobs, S. D.; Lambropoulos, J. C.

    2015-10-01

    We present a modified version of zirconia-coated carbonyl-iron (CI) particles that were invented at the University of Rochester in 2008. The amount of zirconia on the coating is increased to further protect the iron particles from corrosion when introduced to an acidic environment. Five low-pH, magnetorheological (MR) fluids were made with five acids: acetic, hydrochloric, nitric, phosphoric, and hydrofluoric. All fluids were based on the modified zirconia-coated CI particles. Off-line viscosity and pH stability were measured for all acidic MR fluids to determine the ideal fluid composition for acidic MR finishing of chemical-vapor-deposited (CVD) zinc sulfide (ZnS) and other infrared (IR) optical materials, such as hot-isostatic-pressed (HIP) ZnS, CVD zinc selenide (ZnSe), and magnesium fluoride (MgF2). Results show significant reduction in surface artifacts (millimeter-size, pebble-like structures on the finished surface) for several standard-grade CVD ZnS substrates and good surface roughness for the non-CVD MgF2 substrate when MR finished with our advanced acidic MR fluid.

  2. Mussel-inspired modification of dextran for protein-resistant coatings of titanium oxide.

    PubMed

    Park, Jae Yoon; Kim, Jee Seon; Nam, Yoon Sung

    2013-09-12

    Surface modification of inorganic materials to prevent non-specific protein adsorption is critically important for developing a biocompatible materials' platform for medical implantation, diagnostics, and therapeutics. Here we report mussel-inspired chemical modification of dextran for anti-fouling coatings of metal oxide. Catechols are conjugated to dextran via a carbamate ester linkage, producing catechol-grafted dextran with a grafting density of 7.3 mol.%. Titanium dioxide (TiO₂) is coated with the catechol-grafted dextran, and the anti-fouling effect of dextran coatings is examined by using the adsorption of human serum albumin. The mussel-inspired dextran coatings show excellent resistance to non-specific protein adsorption: the adsorption equilibrium constant (K) is 0.69 Lg(-1) for dextran-coated TiO₂ while that for pristine TiO₂ surface is 3.53 Lg(-1). This study suggests that catechol-grafted dextran is a promising material for effective anti-fouling coatings of implantable inorganic materials.

  3. Advanced turbine systems - research and development of thermal barrier coatings technology: 2nd bimonthly report, February 1996

    SciTech Connect

    1996-02-01

    Objective of the ATS program is the development of ultra-highly efficient, environmentally superior, and cost-competitive gas turbine systems, with long, less cyclic operating profiles than aircraft gas turbine engines. Durability and performance demands of ATS can be achieved by means of thermal barrier coatings. Phase I (program plan) is complete. Phase II is in progress.

  4. The synergistic effect of inert oxide and metal fluoride dual coatings on advanced cathode materials for lithium ion battery applications.

    PubMed

    Park, Kwangjin; Lee, Byoung-Sun; Park, Jun-Ho; Hong, Suk-Gi

    2016-06-21

    The effect of Al2O3/LiF dual coatings on the electrochemical performance of over-lithiated layered oxide (OLO) has been investigated. A uniform coating of Al2O3 and LiF is obtained on the surface of the layered pristine material. The OLO with a dual Al2O3/LiF coating with a ratio of 1 : 1.5 exhibits excellent electrochemical performance. An initial discharge capacity of 265.66 mA h g(-1) is obtained at a C-rate of 0.1C. This capacity is approximately 15 mA h g(-1) higher than that of pristine OLO. The capacity retention (92.8% at the 50th cycle) is also comparable to that of pristine OLO (91.4% at the 50th cycle). Coating the cathode with a dual layer comprising Al2O3 and LiF leads to improved charging and discharging kinetics, and prevents direct contact between the cathode and the electrolyte.

  5. Advances in the Development of a WCl6 CVD System for Coating UO2 Powders with Tungsten

    NASA Technical Reports Server (NTRS)

    Mireles, Omar R.; Tieman, Alyssa; Broadway, Jeramie; Hickman, Robert

    2013-01-01

    Demonstrated viability and utilization of: a) Fluidized powder bed. b) WCl6 CVD process. c) Coated spherical particles with tungsten. The highly corrosive nature of the WCl6 solid reagent limits material of construction. Indications that identifying optimized process variables with require substantial effort and will likely vary with changes in fuel requirements.

  6. Advanced surface characterization of silver nanocluster segregation in Ag-TiCN bioactive coatings by RBS, GDOES, and ARXPS.

    PubMed

    Escobar Galindo, R; Manninen, N K; Palacio, C; Carvalho, S

    2013-07-01

    Surface modification by means of wear protective and antibacterial coatings represents, nowadays, a crucial challenge in the biomaterials field in order to enhance the lifetime of bio-devices. It is possible to tailor the properties of the material by using an appropriate combination of high wear resistance (e.g., nitride or carbide coatings) and biocide agents (e.g., noble metals as silver) to fulfill its final application. This behavior is controlled at last by the outmost surface of the coating. Therefore, the analytical characterization of these new materials requires high-resolution analytical techniques able to provide information about surface and depth composition down to the nanometric level. Among these techniques are Rutherford backscattering spectrometry (RBS), glow discharge optical emission spectroscopy (GDOES), and angle resolved X-ray photoelectron spectroscopy (ARXPS). In this work, we present a comparative RBS-GDOES-ARXPS study of the surface characterization of Ag-TiCN coatings with Ag/Ti atomic ratios varying from 0 to 1.49, deposited at room temperature and 200 °C. RBS analysis allowed a precise quantification of the silver content along the coating with a non-uniform Ag depth distribution for the samples with higher Ag content. GDOES surface profiling revealed that the samples with higher Ag content as well as the samples deposited at 200 °C showed an ultrathin (1-10 nm) Ag-rich layer on the coating surface followed by a silver depletion zone (20-30 nm), being the thickness of both layers enhanced with Ag content and deposition temperature. ARXPS analysis confirmed these observations after applying general algorithm involving regularization in addition to singular value decomposition techniques to obtain the concentration depth profiles. Finally, ARXPS measurements were used to provide further information on the surface morphology of the samples obtaining an excellent agreement with SEM observations when a growth model of silver islands with

  7. Click synthesis of neutral, cationic, and zwitterionic poly(propargyl glycolide)-co-poly(ɛ-caprolactone)-based aliphatic polyesters as antifouling biomaterials.

    PubMed

    Tu, Qin; Wang, Jian-Chun; Liu, Rui; Chen, Yun; Zhang, Yanrong; Wang, Dong-En; Yuan, Mao-Sen; Xu, Juan; Wang, Jinyi

    2013-08-01

    With the development of polymer-based biomaterials, aliphatic polyesters have attracted considerable interest because of their non-toxicity, non-allergenic property, and good biocompatibility. However, the hydrophobic nature and the lack of side chain functionalities of aliphatic polyesters limit their biomedical applications. In this study, we prepared four new polyesters: poly(sulfobetaine methacrylate)-, poly(2-methacryloyloxyethyl phosphotidylcholine)-, poly(ethylene glycol)-, and quaternized poly[(2-dimethylamino)ethyl methacrylate]-grafted poly(propargyl glycolide)-co-poly(ɛ-caprolactone). Their synthesis was conducted through ring-opening polymerization of acetylene-functionalized lactones and subsequent graft of bioactive units using click chemistry. The chemical structures of the polyesters were characterized through nuclear magnetic resonance and Fourier-transform infrared spectroscopy, and their physical properties (including molecular weight, glass transition temperature, and melting point) were determined using gel permeation chromatography and differential scanning calorimetry. For studies on their hydrophilicity, stability, and anti-bioadhesive property, a series of polymeric surfaces of these polyesters was prepared by coating them onto glass substrates. The hydrophilicity and stability of these polyester surfaces were examined by contact angle measurements and attenuated total reflection Fourier-transform infrared spectroscopy. Their anti-bioadhesive property was investigated through protein adsorption, as well as cellular and bacterial adhesion assays. The prepared polyesters showed good hydrophilicity and long-lasting stability, as well as significant anti-fouling property. The newly prepared polyesters could be developed as promising anti-fouling materials with extensive biomedical applications.

  8. Applications of advanced electrochemical techniques in the study of microbial fuel cells and corrosion protection by polymer coatings

    NASA Astrophysics Data System (ADS)

    Manohar, Aswin Karthik

    determined by the sum of the polarization resistance of the anode (Rap) and the cathode (Rcp), and therefore Rint depends on V. The ohmic contribution to the Rint was very small. It has been found that Rint decreased with decreasing cell voltage as the increasing current flow decreased R ap and Rcp. In the presence of MR-1, Rint was lower by a factor of about 100 than Rint of the MFC with buffer and lactate as anolyte. Additions of SS balls to the anode compartment produced a very large decrease of Rint. For the MFC containing SS balls in the anode compartment no significant further decrease of Rint could be observed when MR-1 was added to the anolyte. In Chapter 2, EIS has been used to determine the properties and stability of polymer coatings based on different chromate or chromate-free pretreatments and primers. Five sets of coated aluminum 2024 samples were exposed to 0.5N NaCl for a period of 31 days. Impedance spectra of the samples were measured during this period and the changes of the properties of the different coatings were studied as a function of time. From the analysis of the fit parameters of the impedance spectra, it was found that the corrosion protection of the coated samples depended on the type of primer used. The coating with the chromate based primer provided better corrosion protection than the coating with the chromate free primer. After 31 days of exposure, one sample from each set was scribed and exposed to 0.5N NaCl. The corrosion behavior of the scribed coatings was found to be dependent upon the type of pretreatment employed. The samples with the chromate conversion coating pretreatment showed better corrosion resistance in the scribed area than the samples that were treated by the trivalent chromium based method.

  9. Thin film deposition at atmospheric pressure using dielectric barrier discharges: Advances on three-dimensional porous substrates and functional coatings

    NASA Astrophysics Data System (ADS)

    Fanelli, Fiorenza; Bosso, Piera; Mastrangelo, Anna Maria; Fracassi, Francesco

    2016-07-01

    Surface processing of materials by atmospheric pressure dielectric barrier discharges (DBDs) has experienced significant growth in recent years. Considerable research efforts have been directed for instance to develop a large variety of processes which exploit different DBD electrode geometries for the direct and remote deposition of thin films from precursors in gas, vapor and aerosol form. This article briefly reviews our recent progress in thin film deposition by DBDs with particular focus on process optimization. The following examples are provided: (i) the plasma-enhanced chemical vapor deposition of thin films on an open-cell foam accomplished by igniting the DBD throughout the entire three-dimensional (3D) porous structure of the substrate, (ii) the preparation of hybrid organic/inorganic nanocomposite coatings using an aerosol-assisted process, (iii) the DBD jet deposition of coatings containing carboxylic acid groups and the improvement of their chemical and morphological stability upon immersion in water.

  10. Blocked-micropores, surface functionalized, bio-compatible and silica-coated iron oxide nanocomposites as advanced MRI contrast agent

    NASA Astrophysics Data System (ADS)

    Darbandi, Masih; Laurent, Sophie; Busch, Martin; Li, Zi-An; Yuan, Ying; Krüger, Michael; Farle, Michael; Winterer, Markus; Vander Elst, Luce; Muller, Robert N.; Wende, Heiko

    2013-05-01

    Biocompatible magnetic nanoparticles have been found promising in several biomedical applications for tagging, imaging, sensing and separation in recent years. In this article, a systematic study of the design and development of surface-modification schemes for silica-coated iron oxide nanoparticles (IONP) via a one-pot, in situ method at room temperature is presented. Silica-coated IONP were prepared in a water-in-oil microemulsion, and subsequently the surface was modified via addition of organosilane reagents to the microemulsion system. The structure and the morphology of the as synthesized nanoparticles have been investigated by means of transmission electron microscopy (TEM) and measurement of N2 adsorption-desorption. Electron diffraction and high-resolution transmission electron microscopic (TEM) images of the nanoparticles showed the highly crystalline nature of the IONP structures. Nitrogen adsorption indicates microporous and blocked-microporous structures for the silica-coated and amine functionalized silica-coated IONP, respectively which could prove less cytotoxicity of the functionalized final product. Besides, the colloidal stability of the final product and the presence of the modified functional groups on top of surface layer have been proven by zeta-potential measurements. Owing to the benefit from the inner IONP core and the hydrophilic silica shell, the as-synthesized nanocomposites were exploited as an MRI contrast enhancement agent. Relaxometric results prove that the surface functionalized IONP have also signal enhancement properties. These surface functionalized nanocomposites are not only potential candidates for highly efficient contrast agents for MRI, but could also be used as ultrasensitive biological-magnetic labels, because they are in nanoscale size, having magnetic properties, blocked-microporous and are well dispersible in biological environment.

  11. Molecular Design of Antifouling Polymer Brushes Using Sequence-Specific Peptoids

    DOE PAGES

    Lau, King Hang Aaron; Sileika, Tadas S.; Park, Sung Hyun; ...

    2014-11-26

    Material systems that can be used to flexibly and precisely define the chemical nature and molecular arrangement of a surface would be invaluable for the control of complex biointerfacial interactions. For example, progress in antifouling polymer biointerfaces that prevents nonspecific protein adsorption and cell attachment, which can significantly improve the performance of an array of biomedical and industrial applications, is hampered by a lack of chemical models to identify the molecular features conferring their properties. Poly(N-substituted glycine) “peptoids” are peptidomimetic polymers that can be conveniently synthesized with specific monomer sequences and chain lengths, and are presented as a versatile platformmore » for investigating the molecular design of antifouling polymer brushes. Zwitterionic antifouling polymer brushes have captured significant recent attention, and a targeted library of zwitterionic peptoid brushes with different charge densities, hydration, separations between charged groups, chain lengths, and grafted chain densities, is quantitatively evaluated for their antifouling properties through a range of protein adsorption and cell attachment assays. Specific zwitterionic brush designs are found to give rise to distinct but subtle differences in properties. In conclusion, the results also point to the dominant roles of the grafted chain density and chain length in determining the performance of antifouling polymer brushes.« less

  12. Molecular Design of Antifouling Polymer Brushes Using Sequence-Specific Peptoids

    SciTech Connect

    Lau, King Hang Aaron; Sileika, Tadas S.; Park, Sung Hyun; Sousa, Ana M. L.; Burch, Patrick; Szleifer, Igal; Messersmith, Phillip B.

    2014-11-26

    Material systems that can be used to flexibly and precisely define the chemical nature and molecular arrangement of a surface would be invaluable for the control of complex biointerfacial interactions. For example, progress in antifouling polymer biointerfaces that prevents nonspecific protein adsorption and cell attachment, which can significantly improve the performance of an array of biomedical and industrial applications, is hampered by a lack of chemical models to identify the molecular features conferring their properties. Poly(N-substituted glycine) “peptoids” are peptidomimetic polymers that can be conveniently synthesized with specific monomer sequences and chain lengths, and are presented as a versatile platform for investigating the molecular design of antifouling polymer brushes. Zwitterionic antifouling polymer brushes have captured significant recent attention, and a targeted library of zwitterionic peptoid brushes with different charge densities, hydration, separations between charged groups, chain lengths, and grafted chain densities, is quantitatively evaluated for their antifouling properties through a range of protein adsorption and cell attachment assays. Specific zwitterionic brush designs are found to give rise to distinct but subtle differences in properties. In conclusion, the results also point to the dominant roles of the grafted chain density and chain length in determining the performance of antifouling polymer brushes.

  13. On the hydration of subnanometric antifouling organosilane adlayers: a molecular dynamics simulation.

    PubMed

    Sheikh, Sonia; Blaszykowski, Christophe; Nolan, Robert; Thompson, Damien; Thompson, Michael

    2015-01-01

    The connection between antifouling and surface hydration is a fascinating but daunting question to answer. Herein, we use molecular dynamics (MD) computer simulations to gain further insight into the role of surface functionalities in the molecular-level structuration of water (surface kosmotropicity)--within and atop subnanometric organosilane adlayers that were shown in previous experimental work to display varied antifouling behavior. Our simulations support the hypothesized intimate link between surface hydration and antifouling, in particular the importance of both internal and interfacial hydrophilicity and kosmotropicity. The antifouling mechanism is also discussed in terms of surface dehydration energy and water dynamicity (lability and mobility), notably the crucial requirement for clustered water molecules to remain tightly bound for extensive periods of time--i.e. exhibit slow exchange dynamics. A substrate effect on surface hydration, which would also participate in endowing antifouling adlayers with hydrogel-like characteristics, is also proposed. In contrast, the role of adlayer flexibility, if any, is assigned a secondary role in these ultrathin structures made of short building blocks. The conclusions from this work are well in line with those previously drawn in the literature.

  14. Characterization of terpenoids from the root of Ceriops tagal with antifouling activity.

    PubMed

    Chen, Jun-De; Yi, Rui-Zao; Lin, Yi-Ming; Feng, Dan-Qing; Zhou, Hai-Chao; Wang, Zhan-Chang

    2011-01-01

    One new dimeric diterpenoid, 8(14)-enyl-pimar-2'(3')-en-4'(18')-en-15'(16')-endolabr- 16,15,2',3'-oxoan-16-one (1) and five known terpenoids: Tagalsin C (2), Tagalsin I (3), lup-20(29)-ene-3β,28-diol (4), 3-oxolup-20(29)-en-28-oic acid (5) and 28-hydroxylup- 20(29)-en-3-one (6) were isolated from the roots of the mangrove plant Ceriops tagal. Their structures and relative stereochemistry were elucidated by means of extensive NMR, IR and MS analysis. The antifouling activity against larval settlement of the barnacle Balanus albicostatus were evaluated using capsaicin as a positive control. All these terpenoids exhibited antifouling activity against cyprid larvae of the barnacle without significant toxicity. The structure-activity relationship results demonstrated that the order of antifouling activity was diterpenoid (Compound 2) > triterpenoid (Compounds 4, 5 and 6) > dimeric diterpenoid (Compounds 1 and 3). The functional groups on the C-28 position of lupane triterpenoid significantly affect the antifouling activity. The diterpenoid dimmer with two identical diterpenoid subunits might display more potent antifouling activity than one with two different diterpenoid subunits. The stability test showed that Compounds 2, 4, 5 and 6 remained stable over 2-month exposure under filtered seawater.

  15. Evaluation of toxicity of capsaicin and zosteric acid and their potential application as antifoulants.

    PubMed

    Xu, Qingwei; Barrios, Carlos A; Cutright, Teresa; Zhang Newby, Bi-min

    2005-10-01

    The toxicity of two natural product antifoulants, capsaicin and zosteric acid, was evaluated using the Microtox assay and a static toxicity test. The EC50 values obtained from the Microtox assay for capsaicin and zosteric acid were 11.75 +/- 1.02 and 442 +/- 100 mg/L, respectively. The static toxicity test, conducted with freshwater organisms, yielded capsaicin EC50 values of 5.5 +/- 0.5 and 23 +/- 2.0 mg/L for P. putida and Lake Erie bacteria, respectively. Zosteric acid EC50 values were 167 +/- 3.9 and 375 +/- 10 mg/L for P. putida and Lake Erie bacteria, respectively. Tests with marine organisms resulted in capsaicin EC50 values of 6.9 +/- 0.2 and 15.6 +/- 0.4 mg/L for V. natriegens and V. parahaemolyticus, respectively; whereas zosteric acid EC50 values were 7.4 +/- 0.1 and 18 +/- 0.6 mg/L for V. natriegens and V. parahaemolyticus, respectively. These results indicate that zosteric acid is much less toxic than capsaicin and that both are substantially less toxic than the currently used antifoulants, such as TBT (EC50 < 0.01 ppb). Their effectiveness as natural antifoulants was demonstrated by preliminary attachments studies. As the aqueous antifoulant concentration increased, significant inhibition of bacteria attachment or prevention of biofilm formation was achieved. Hence, both capsaicin and zosteric acid could be attractive alternatives as new antifouling compounds.

  16. Molecular Understanding and Structural-Based Design of Polyacrylamides and Polyacrylates as Antifouling Materials.

    PubMed

    Chen, Hong; Zhao, Chao; Zhang, Mingzhen; Chen, Qiang; Ma, Jie; Zheng, Jie

    2016-04-12

    Design and synthesis of highly bioinert and biocompatible antifouling materials are crucial for a broad range of biomedical and engineering applications. Among antifouling materials, polyacrylamides and polyacrylates have proved so promising because of cheap raw materials, ease of synthesis and applicability, and abundant functional groups. The strong surface hydration and the high surface packing density of polyacrylamides and polyacrylates are considered to be the key contributors to their antifouling property. In this article, we review our studies on the design and synthesis of a series of polyacrylamides and polyacrylates with different molecular structures. These polymers can be fabricated into different architectural forms (brushes, nanoparticles, nanogels, and hydrogels), all of which are highly resistant to the attachment of proteins, cells, and bacteria. We find that small structural changes in the polymers can lead to large enhancement in surface hydration and antifouling performance, both showing a positive correlation. This reveals a general design rule for effective antifouling materials. Furthermore, polyacrylamides and polyacrylates are readily functionalized with other bioactive compounds to achieve different new multifunctionalities.

  17. Preparation of hydrophilic vinyl chloride copolymer hollow fiber membranes with antifouling properties

    NASA Astrophysics Data System (ADS)

    Rajabzadeh, Saeid; Sano, Rie; Ishigami, Toru; Kakihana, Yuriko; Ohmukai, Yoshikage; Matsuyama, Hideto

    2015-01-01

    Hydrophilic vinyl chloride copolymer hollow fiber membranes with antifouling properties were prepared from brominated vinyl chloride-hydroxyethyl methacrylate copolymer (poly(VC-co-HEMA-Br)). The base membrane was grafted with two different zwitterionic monomers, (2-methacryloyloxyethylphosphorylcholine) (MPC) and [2-(methacryloyloxy) ethyl] dimethyl (3-sulfopropyl) ammonium hydroxide) (MEDSAH), and poly(ethylene glycol) methyl ether methacrylate (PEGMA). The effect of the grafting on the base membrane hydrophilicity and antifouling properties was investigated. For comparison of the results, the pure water permeabilities and pore sizes at the outer surfaces of the grafted hollow fiber membranes were controlled to be similar. A poly(VC-co-HEMA-Br) hollow fiber membrane with similar pure water permeability and pore size was also prepared as a control membrane. A BSA solution was used as a model fouling solution for evaluation of the antifouling properties. Grafting with zwitterionic monomers and PEGMA improved the antifouling properties compared with the control membrane. The PEGMA grafted membrane showed the best antifouling properties among the grafted membranes

  18. Measurement of copper release rates from antifouling paint under laboratory and in situ conditions: implications for loading estimation to marine water bodies.

    PubMed

    Valkirs, Aldis O; Seligman, Peter F; Haslbeck, Elizabeth; Caso, Joaquin S

    2003-06-01

    The release of biocides, such as copper (Cu), from antifouling (AF) coatings on vessel hulls represents a significant proportion of overall Cu loading in those harbors and estuaries where substantial numbers of small craft or large vessels are berthed. Copper release rates were measured on several self-polishing, tin-free coatings and an ablative Cu reference coating applied to steel panels using three measurement methods. The panels were exposed in natural seawater in San Diego Bay, and release rates were measured both in the laboratory and field over 2 years. Results with the static (20 cm x 30 cm) panels indicated that Cu release rates were initially high (25-65 microg Cu cm(-2)day(-1)), with a large range of values between paint types. Release rates declined to substantially lower rates (8-22 microg cm(-2)day(-1)) with reduced variability within 2 months. Release rates continued to decrease over time for approximately 6 months when relatively constant release rates were observed for most coatings. Over time, relative differences in Cu release rates measured by three exposure methods decreased, with all coatings exhibiting similar behavior toward the end of the study. Lowest overall Cu release rates were observed with the self-polishing experimental paint no. 7 in static-dynamic and in situ treatments. The highest periodic release rates were measured from panels that experienced periods of both static and dynamic exposure (8.7 ms(-1) rotation). The lowest release rates were measured from panels that experienced static, constant depth exposure, and where release rates were evaluated in situ, using a novel diver-deployed measurement system. Results from this in situ technique suggests that it more closely reflects actual Cu release rates on vessel hulls measured with intact natural biofilms under ambient conditions than measurements using standardized laboratory release rate methods. In situ measurements made directly on the AF surface of vessels demonstrated

  19. Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS.

    PubMed

    Belsey, Natalie A; Cant, David J H; Minelli, Caterina; Araujo, Joyce R; Bock, Bernd; Brüner, Philipp; Castner, David G; Ceccone, Giacomo; Counsell, Jonathan D P; Dietrich, Paul M; Engelhard, Mark H; Fearn, Sarah; Galhardo, Carlos E; Kalbe, Henryk; Won Kim, Jeong; Lartundo-Rojas, Luis; Luftman, Henry S; Nunney, Tim S; Pseiner, Johannes; Smith, Emily F; Spampinato, Valentina; Sturm, Jacobus M; Thomas, Andrew G; Treacy, Jon P W; Veith, Lothar; Wagstaffe, Michael; Wang, Hai; Wang, Meiling; Wang, Yung-Chen; Werner, Wolfgang; Yang, Li; Shard, Alexander G

    2016-10-27

    We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) inter-laboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and; particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS). Careful data analysis revealed some significant sources of discrepancy, particularly for XPS. Degradation during transportation, storage or sample preparation resulted in a variability in thickness of 53 %. The calculation method chosen by XPS participants contributed a variability of 67 %. However, variability of 12 % was achieved for the samples deposited using a single method and by choosing photoelectron peaks that were not adversely affected by instrumental transmission effects. The study identified a need for more consistency in instrumental transmission functions and relative sensitivity factors, since this contributed a variability of 33 %. The results from the LEIS participants were more consistent, with variability of less than 10 % in thickness and this is mostly due to a common method of data analysis. The calculation was performed using a model developed for uniform, flat films and some participants employed a correction factor to account for the sample geometry, which appears warranted based upon a simulation of LEIS data from one of the participants and comparison to the XPS results.

  20. Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS

    SciTech Connect

    Belsey, Natalie A.; Cant, David J. H.; Minelli, Caterina; Araujo, Joyce R.; Bock, Bernd; Brüner, Philipp; Castner, David G.; Ceccone, Giacomo; Counsell, Jonathan D. P.; Dietrich, Paul M.; Engelhard, Mark H.; Fearn, Sarah; Galhardo, Carlos E.; Kalbe, Henryk; Kim, Jeong Won; Lartundo-Rojas, Luis; Luftman, Henry S.; Nunney, Tim S.; Pseiner, Johannes; Smith, Emily F.; Spampinato, Valentina; Sturm, Jacobus M.; Thomas, Andrew G.; Treacy, Jon P. W.; Veith, Lothar; Wagstaffe, Michael; Wang, Hai; Wang, Meiling; Wang, Yung-Chen; Werner, Wolfgang; Yang, Li; Shard, Alexander G.

    2016-10-27

    We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) inter-laboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and; particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS). Careful data analysis revealed some significant sources of discrepancy, particularly for XPS. Degradation during transportation, storage or sample preparation resulted in a variability in thickness of 53 %. The calculation method chosen by XPS participants contributed a variability of 67 %. However, variability of 12 % was achieved for the samples deposited using a single method and by choosing photoelectron peaks that were not adversely affected by instrumental transmission effects. The study identified a need for more consistency in instrumental transmission functions and relative sensitivity factors, since this contributed a variability of 33 %. The results from the LEIS participants were more consistent, with variability of less than 10 % in thickness and this is mostly due to a common method of data analysis. The calculation was performed using a model developed for uniform, flat films and some participants employed a correction factor to account for the sample geometry, which appears warranted based upon a simulation of LEIS data from one of the participants and comparison to the XPS results.

  1. Copper and copper-nickel alloys as zebra mussel antifoulants

    SciTech Connect

    Dormon, J.M.; Cottrell, C.M.; Allen, D.G.; Ackerman, J.D.; Spelt, J.K.

    1996-04-01

    Copper has been used in the marine environment for decades as cladding on ships and pipes to prevent biofouling by marine mussels (Mytilus edulis L.). This motivated the present investigation into the possibility of using copper to prevent biofouling in freshwater by both zebra mussels and quagga mussels (Dreissena polymorpha and D. bugensis collectively referred to as zebra mussels). Copper and copper alloy sheet proved to be highly effective in preventing biofouling by zebra mussels over a three-year period. Further studies were conducted with copper and copper-nickel mesh (lattice of expanded metal) and screen (woven wire with a smaller hole size), which reduced the amount of copper used. Copper screen was also found to be strongly biofouling-resistant with respect to zebra mussels, while copper mesh reduced zebra mussel biofouling in comparison to controls, but did not prevent it entirely. Preliminary investigations into the mechanism of copper antifouling, using galvanic couples, indicated that the release of copper ions from the surface of the exposed metal into the surrounding water is directly or indirectly responsible for the biofouling resistance of copper.

  2. Combining a photocatalyst with microtopography to develop effective antifouling materials.

    PubMed

    Vucko, M J; Poole, A J; Sexton, B A; Glenn, F L; Carl, C; Whalan, S; de Nys, R

    2013-01-01

    Polydimethylsiloxane surfaces textured with a square-wave linear grating profile (0, 20, 200, 300 and 600 μm), and embedded with a range of photocatalytic titanium dioxide (TiO2) nanoparticle loadings (3.75, 7.5, 11.25 and 15 wt.%), were used to test the combined efficacy of these technologies as antifouling materials. Settlement of the fouling bryozoan species Bugula neritina was quantified in the laboratory under two intensities of UV light. The lowest settlement rates were observed on 20 μm surfaces. However, texture effects were not as critical to larval settlement as the presence of TiO2. In conjunction with UV light, TiO2 completely inhibited larval metamorphosis even at the lowest loading (3.75 wt.%) and the lowest intensity of UV light (24 W m(-2)). Recruitment of B. neritina was also quantified in field trials and showed similar results to laboratory assays. The lowest recruitment was observed on 20 and 200 μm surfaces, with recruitment being significantly lower on all surfaces containing TiO2. Therefore for B. neritina, although all TiO2 loadings were effective, 3.75 wt.% can be used as a minimum inhibitory concentration to deter larval settlement and the addition of a 20 μm texture further increases the deterrent effect.

  3. AFCATT (Anti-Fouling Chemical Additive Test Tower)

    SciTech Connect

    Philpot, E.F.; Newton, M.T.; Noble, R.T.

    1995-06-01

    Polyvinylchloride (PVC) film-type cellular fill is the fill of choice in replacing cement asbestos board fill in existing cooling towers and in new cooling towers because of its high thermal performance, ease of installation, and low initial cost. However, PVC fill has been found to foul quickly with biological and sediment material, significantly reducing tower performance and the fill`s useful life. The Anti-Fouling Chemical Additives Test Tower (AFCATT) has been build to study accumulation rates of fouling deposits in corrugated PVC film fill and to study methods of cleaning and preventing the fouling deposits. This small mechanical draft cooling tower is located next to the Unit 4 natural draft cooling tower at Georgia Power Company`s Plant Bowen. The once-through mechanical draft tower receives hot water from the condenser and returns the cold water to the basin of the host tower. The pilot tower is divided into four chambers allowing for three different treatment programs and one control to be run simultaneously. PVC fill packs are suspended from load cells to allow the weight of the fill packs to be measured continuously. Six vendors participated in the summer 1993 test program. Each proposed different methods of cleaning the fouled fill and were given the opportunity to try their proposed method of fill cleaning. To determine the success of these different treatment programs, statistical analyses were performed on the collected data and the changes in the accumulation rates compared.

  4. Inhibition of coral photosynthesis by the antifouling herbicide Irgarol 1051.

    PubMed

    Owen, Richard; Knap, Anthony; Toaspern, Megan; Carbery, Kelly

    2002-07-01

    International regulation of organotin compounds for use in antifouling paints has led to the development and increased use of replacement compounds, notably the s-triazine herbicide Irgarol 1051. Little is known about the distribution of Irgarol 1051 in tropical waters. Nor has the potential impact of this triazine upon photosynthesis of endosymbiotic microalgae (zooxanthellae) in corals been assessed. In this study Irgarol 1051 was detected in marinas, harbours and coastal waters of the Florida Keys, Bermuda and St. Croix, with concentrations ranging between 3 and 294 ng 1(-1). 14C incubation experiments with isolated zooxanthellae from the common inshore coral Madracis mirabilis showed no incorporation of H14CO3- from the sea water medium after 4-8 h exposure to Irgarol 1051 concentrations as low as 63 ng 1(-1). Reduction in net photosynthesis of intact corals was found at concentrations of l00 ng 1(-1) with little or no photosynthesis at concentrations exceeding 1000 ng 1(-1) after 2-8 h exposure at all irradiances. The data suggest Irgarol 1051 to be both prevalent in tropical marine ecosystems and a potent inhibitor of coral photosynthesis at environmentally relevant concentrations.

  5. Designing thermo-responsive nanocomposites with anti-fouling properties

    NASA Astrophysics Data System (ADS)

    Liu, Ya; McFarlin, Gerald; Yong, Xin; Kuksenok, Olga; Balazs, Anna

    2015-03-01

    Inspired by marine organisms that utilize active ``defense'' (such as active cilia) to prevent the biofouling of their surfaces, we use computational modeling to design synthetic gel-based composite films that provide dual ``defense'' for antifouling applications. We design a nanocomposite gel film that can be harnessed to repel a variety of particles via either a temperature change or an imposed shear. Incorporation of stiff hydrophobic posts into a gel composed of cross-linked poly(N-isoproylacrylamide) chains allows us to drastically alter the film's surface properties when gel undergoes temperature-induced volume phase transition. Depending on whether the system's temperature is below or above the lower critical solution temperature (LCST) of the gel, the posts are hidden in the swollen gel or exposed to the external solution. We model our system using dissipative particle dynamics (DPD); we validate our model through comparisons with Flory-Rehner theory. We focus on the influence of shear and temperature on the position of the particle in the system and isolate the conditions under which adsorption of particles of different sizes to the substrate is effectively prevented.

  6. Advanced fibroblast proliferation inhibition for biocompatible coating by electrostatic layer-by-layer assemblies of heparin and chitosan derivatives.

    PubMed

    Follmann, Heveline D M; Naves, Alliny F; Martins, Alessandro F; Félix, Olivier; Decher, Gero; Muniz, Edvani C; Silva, Rafael

    2016-07-15

    Heparin and different chitosan derivatives were applied to produce stable electrostatic layer-by-layer assemblies and further used as coating technique to inhibit natural inflammatory response to implants. Heparin was assembled with chitosan and N-methylated chitosan derivatives, namely N,N-dimethyl chitosan (DMC) and N,N,N-trimethyl chitosan (TMC), by dipping method. DMC and TMC (chitosan derivatives) were synthesized and characterized before LbL assembly. Ellipsometry, quartz crystal microbalance (QCM-D), and contact angle were used to demonstrate the deposition of polyelectrolyte multilayers onto silicon wafers using polyelectrolyte solutions with different ionic strength. The biological properties of these films were evaluated by cell culture assays using NIH/3T3 fibroblast cells. LbL assemblies of Heparin and chitosan derivatives showed to be biocompatible, and at the same time they strongly hinder the proliferation speed of fibroblasts up to 40-fold factors. Therefore, the multilayers prepared from heparin and chitosan derivatives have good features to be used as an alternative coating treatment for biomedical implants with reduced body rejection properties.

  7. Advanced Spin Coating Film Transfer and Hot-Pressing Process for Global Planarization with Dielectric-Material-Viscosity Control

    NASA Astrophysics Data System (ADS)

    Sato, Norio; Machida, Katsuyuki; Yano, Masaki; Kudou, Kazuhisa; Kyuragi, Hakaru

    2002-04-01

    A novel method of controlling the viscosity of dielectric material was developed for global planarization by the spin coating film transfer and hot-pressing (STP) technique. In the STP technique, a base film is spin-coated with a dielectric, the dielectric is hot-pressed to a wafer in vacuum, and the base film is then peeled off from the dielectric. For global planarization in the above steps, the viscosity of the dielectric material is one of the most important factors. We propose controlling the viscosity by vacuum drying in the process chamber. The relationship between viscosity and vacuum drying was investigated experimentally, and the effect of viscosity on gap-filling was clarified by analytical modeling. We applied the control method to STP experiments using patterned wafers and a low-k organic material, and found that it achieves complete gap-filling and good uniformity in film thickness. STP planarized line-and-spaces as large as 100 μm wide achieving a small variation in planarity of ± 0.43%. With this viscosity-control method, the STP technique is applicable to low-k materials.

  8. Electrospark deposition coatings

    NASA Astrophysics Data System (ADS)

    Sheely, W. F.

    1986-11-01

    Hard surfacing for wear resistant and low-friction coatings has been improved by means of advances in the computer controls in electronic circuitry of the electrospark deposition (ESD) process. coatings of nearly any electrically conductive metal alloy or cermet can be deposited on conductive materials. Thickness is usually two mils or less, but can be as high as 10 mils. ESD coatings can quadrupole cutting tool life.

  9. Electrospark deposition coatings

    SciTech Connect

    Sheely, W.F.

    1986-11-19

    Hard surfacing for wear resistant and low-friction coatings has been improved by means of advances in the computer controls in electronic circuitry of the electrospark deposition (ESD) process. coatings of nearly any electrically conductive metal alloy or cermet can be deposited on conductive materials. Thickness is usually two mils or less, but can be as high as 10 mils. ESD coatings can quadrupole cutting tool life. (DLC)

  10. Hydrophilicity and antifouling property of membrane materials from cellulose acetate/polyethersulfone in DMAc.

    PubMed

    Sun, Zhonghua; Chen, Fushan

    2016-10-01

    In this study, cellulose acetate (CA) was blended with polyethersulfone (PES) to endow the ultrafiltration membrane with the improved hydrophilicity and antifouling property by using N,N-dimethylacetamide (DMAc) as the solvent. The effects of blend composition and evaporation time on the mechanical strength and pure water flux were investigated. It was found that the optimal composition of the casting solution was: 18wt% (PES), 4wt% (Polyvinylpyrrolidone K30), 3wt% (CA) and 20s (Evaporation time). The characteristics of CA-PES blend membranes were investigated through the methods of contact angle goniometer, antifouling property, compatibility, thermo gravimetric analysis and SEM. The results showed that the hydrophilicity and antifouling property of CA-PES ultrafiltration membranes were enhanced in comparison with the pure PES membranes. The CA-PES membranes exhibited semi-compatibility and good thermal stability below 270°C. This study provided a potential industrial application prospect of CA-PES membranes prepared in DMAc.

  11. Enhanced permeability, selectivity, and antifouling ability of CNTs/Al2O3 membrane under electrochemical assistance.

    PubMed

    Fan, Xinfei; Zhao, Huimin; Liu, Yanming; Quan, Xie; Yu, Hongtao; Chen, Shuo

    2015-02-17

    Membrane filtration provides effective solutions for removing contaminants, but achieving high permeability, good selectivity, and antifouling ability remains a great challenge for existing membrane filtration technologies. In this work, membrane filtration coupled with electrochemistry has been developed to enhance the filtration performance of a CNTs/Al2O3 membrane. The as-prepared CNTs/Al2O3 membrane, obtained by coating interconnected CNTs on an Al2O3 substrate, presented good pore-size tunability, mechanical stability, and electroconductivity. For the removal of a target (silica spheres as a probe) with a size comparable to the membrane pore size, the removal efficiency and flux at +1.5 V were 1.1 and 1.5 times higher, respectively, than those without electrochemical assistance. Moreover, the membrane also exhibited a greatly enhanced removal efficiency for contaminants smaller than the membrane pores, providing enhancements of 4 orders of magnitude and a factor of 5.7 for latex particles and phenol, respectively. These results indicated that both the permeability and the selectivity of CNTs/Al2O3 membranes can be significantly improved by electrochemical assistance, which was further confirmed by the removal of natural organic matter (NOM). The permeate flux and NOM removal efficiency at +1.5 V were about 1.6 and 3.0 times higher, respectively, than those without electrochemical assistance. In addition, the lost flux of the fouled membrane was almost completely recovered by an electrochemically assisted backwashing process.

  12. Influence of the molecular design on the antifouling performance of poly(ethylene glycol) monolayers grafted on (111) Si.

    PubMed

    Perez, Emmanuel; Lahlil, Khalid; Rougeau, Cyrille; Moraillon, Anne; Chazalviel, Jean-Noël; Ozanam, François; Gouget-Laemmel, Anne Chantal

    2012-10-16

    Various poly(ethylene glycol) monomethyl ether moieties were grafted onto hydrogenated silicon surfaces in order to investigate the influence of the molecular design on the antifouling performance of such coatings. The grafted chains were either oligo(ethylene oxide) chains (EG)(n)OMe bound to silicon via Si-O-C covalent bonds, or hybrid alkyl/oligo(ethylene oxide) chains C(p)(EG)(n)OMe bound via Si-C covalent bonds (from home-synthesized precursors). Quantitative IR spectroscopy gave the molecular coverage of the grafted layers, and AFM imaging demonstrated that a proper surfactinated rinse yields C(p)(EG)(n)OMe layers free of unwanted residues. The protein-repellent character of these grafted layers (here, toward BSA) was studied by IR and AFM imaging. C(p)(EG)(n)OMe layers exhibit a lower surface concentration than (EG)(n)OMe layers, because of the presence of a solvent in the grafting solution; they however demonstrate high resistance against BSA adsorption for high values of the n/p ratio and a higher stability than (EG)(n)OMe. This behavior is consistently explained by the poor ordering capability of the alkyl part of the layer, contrary to what is observed for similar layers on Au, and the key role of an entangled arrangement of the ethylene oxide chains which forms when these chains are long enough.

  13. Impact-Resistant Ceramic Coating

    NASA Technical Reports Server (NTRS)

    Wheeler, W. H.; Creedon, J. F.; Izu, Y. D.

    1986-01-01

    Refractory fibers more than double strength of coating. Impact strengths of ceramic coatings increase with increasing whisker content. Silicon carbide whiskers clearly produce largest increase, and improvement grows even more with high-temperature sintering. Coating also improves thermal and mechanical properties of electromagnetic components, mirrors, furnace linings, and ceramic parts of advanced internal-combustion engines.

  14. Managing the Use of Copper-Based Antifouling Paints

    NASA Astrophysics Data System (ADS)

    Srinivasan, Mridula; Swain, Geoffrey W.

    2007-03-01

    Copper is the biocide of choice for present-day antifouling (AF) paints. It is also a major source of copper loading in to the marine environment and, as such, might cause local copper levels to exceed water quality criteria. The present study is multifaceted and looks into the overall impact of copper-based AF paints on copper concentrations along a 64-km stretch of the Indian River Lagoon and at Port Canaveral, Florida. This preliminary study is one of the first to outline issues and present background evidence on the current status of copper and copper-based AF usage in Florida and to address the need for management. Previous measurements of copper levels in these waters show a history of copper contamination close to marinas, boatyards, and at Port Canaveral that often exceed state and federal water quality standards. Further, we estimate that the total annual copper input into the Indian River Lagoon is between 1.7 tons/year (sailboats) and 2.1 tons/year (powerboats) from boats in 14 marinas. We estimate the copper input into Port Canaveral to be about 1.4 tons/year from seven cruise ships. A brief survey of marina operators and boat owners revealed attitudes and practices associated with AF paint usage that ranged from excellent to inferior. Management recommendations are made for a proactive approach to improving AF paint selection and application, assessing the environmental status of copper, and redefining existing management practices for sustainable AF paint usage and environmental health.

  15. Pyrithiones as antifoulants: environmental fate and loss of toxicity.

    PubMed

    Turley, Patricia A; Fenn, Robert J; Ritter, James C; Callow, Maureen E

    2005-01-01

    The environmental fate and the loss of toxicity of two important antifouling actives, zinc pyrithione (ZnPT) and copper pyrithione (CuPT), were investigated using a bioassay study and an outdoor microcosm study. The bioassay used inhibition of the growth of a marine diatom (Amphora coffeaeformis) to measure the toxicity of ZnPT and CuPT over time in sterile, natural, and sediment-supplemented seawater. In natural seawater and sediment-supplemented seawater in the dark and in sterile seawater exposed to light, growth inhibition was reduced at rates corresponding to the rapid degradation rates for ZnPT and CuPT measured in previous aquatic metabolism, die-away, and photolysis studies. Similarly, the bioassay results from sterile seawater in the dark were consistent with the slower degradation rates measured in abiotic hydrolysis studies. In addition to corroborating the rapid degradation of pyrithione upon exposure to light or sediment, the loss of toxicity indicated that the degradation products were not toxic at the concentrations produced from the dose, which was much higher than predicted environmental concentrations. To supplement environmental fate studies designed to elucidate single-pathway transformations, a microcosm study was conducted to integrate all of the degradation pathways. The study used two sediment and water systems, one of which was dosed during the day and the other at night. The pyrithione degraded rapidly in the water phase, with very little accumulation in the sediment. 2-Pyridine sulfonic acid (PSA) and carbon dioxide were the only detectable degradation products 30 d after dosing. Aquatic toxicity studies with PSA showed no observable effect at concentrations at least three orders of magnitude higher than those for either ZnPT or CuPT. As a result, the worst-case environmental concentration of PSA is expected to be far below the no observable effect concentration.

  16. Free-standing CuO nanoflake arrays coated Cu foam for advanced lithium ion battery anodes

    NASA Astrophysics Data System (ADS)

    Yang, Wanfeng; Wang, Jiawei; Ma, Wensheng; Dong, Chaoqun; Cheng, Guanhua; Zhang, Zhonghua

    2016-11-01

    For lithium ion batteries (LIBs), low electronic conductivity of CuO leads to rapid capacity decay and poor structural stability. Herein, we successfully fabricate three-dimensional CuO nanoflake arrays coated Cu foam by facile and efficient electrochemical oxidation. When being applied as anode material for LIBs, the CuO electrodes deliver stable reversible capacities of 523.9 mA h g-1 at 0.5 A g-1, 376.1 mA h g-1 at 1.0 A g-1 and 322.7 mA h g-1 at 2.0 A g-1 with high coulombic efficiency (>99%) after 100 cycles. A long cycle life of up to 400 cycles at 2.0 A g-1 is also achieved with the retention capacity of 193.5 mA h g-1. Moreover, the electrode exhibits excellent rate capability and can regain its original capacities as reversing to the low current densities. Noticeably, on-line differential electrochemical mass spectrometry and in situ Raman measurements confirm the formation of solid electrolyte interface film and the conversion mechanism for the CuO electrodes, respectively. The superior lithium storage performance can be attributed to the favorable nanoflake structures with high surface area and the perfect electrical contact between CuO and Cu substrate.

  17. Advanced Na-NiCl2 Battery Using Nickel-Coated Graphite with Core-Shell Microarchitecture.

    PubMed

    Chang, Hee-Jung; Canfield, Nathan L; Jung, Keeyoung; Sprenkle, Vincent L; Li, Guosheng

    2017-04-05

    Stationary electric energy storage devices (rechargeable batteries) have gained increasing prominence due to great market needs, such as smoothing the fluctuation of renewable energy resources and supporting the reliability of the electric grid. With regard to raw materials availability, sodium-based batteries are better positioned than lithium batteries due to the abundant resource of sodium in Earth's crust. However, the sodium-nickel chloride (Na-NiCl2) battery, one of the most attractive stationary battery technologies, is hindered from further market penetration by its high material cost (Ni cost) and fast material degradation at its high operating temperature. Here, we demonstrate the design of a core-shell microarchitecture, nickel-coated graphite, with a graphite core to maintain electrochemically active surface area and structural integrity of the electron percolation pathway while using 40% less Ni than conventional Na-NiCl2 batteries. An initial energy density of 133 Wh/kg (at ∼C/4) and energy efficiency of 94% are achieved at an intermediate temperature of 190 °C.

  18. Coatings for directional eutectics

    NASA Technical Reports Server (NTRS)

    Rairden, J. R.; Jackson, M. R.

    1976-01-01

    Significant advances have been made in the development of an environmentally stable coating for a very high strength, directionally solidified eutectic alloy designated NiTaC-13. Three duplex (two-layer) coatings survived 3,000 hours on a cyclic oxidation test (1,100 C to 90 C). These coatings were fabricated by first depositing a layer of NiCrAl(Y) by vacuum evaporation from an electron beam heated source, followed by depositing an aluminizing overlayer. The alloy after exposure with these coatings was denuded of carbide fibers at the substrate/coating interface. It was demonstrated that TaC fiber denudation can be greatly retarded by applying a carbon-bearing coating. The coating was applied by thermal spraying followed by aluminization. Specimens coated with NiCrAlCY+Al survived over 2,000 hours in the cyclic oxidation test with essentially no TaC denudation. Coating ductility was studied for coated and heat-treated bars, and stress rupture life at 871 C and 1,100 C was determined for coated and cycled bars.

  19. Environmental Effects from In-Water Hull Cleaning of Ablative Copper Antifouling Coatings

    DTIC Science & Technology

    1994-07-01

    inverte - brate species are located in this region. The naval region includes several ship berthing areas and is moderately well-flushed. Marinas and...and Abatement Order (N. 85-91) to PACO Terminals, Inc., calling for the abatement of all copper discharge from the site and cleanup of copper-containing...VERSION 3.0. Fish Physiology and Toxicology Laboratory, Dept. of Zoology and Physiology, University of Wyoming, Laramie, Wyoming. Hazel, C.R. and S.J

  20. In Situ Determination of Butyltin Release Rates from Antifouling Coatings on Navy Test Ships

    DTIC Science & Technology

    1985-07-01

    difference in the quantity of dibutyltin present in the leachate from the different paint systems. Measure- ments of the ABC-2 paint system on the MRYERKORD...and on a test panel show the dibutyltin component ranged from 13 to 38 percent with a mean of 28 percent for the eight samples measured. in contrast...these differences represent a dibutyltin impurity in the ABC-2 paint or some difference in the degradation of the tributyltin for the different paint

  1. A hierarchical polymer brush coating with dual-function antibacterial capability.

    PubMed

    Yan, Shunjie; Song, Lingjie; Luan, Shifang; Xin, Zhirong; Du, Shanshan; Shi, Hengchong; Yuan, Shuaishuai; Yang, Yuming; Yin, Jinghua

    2017-01-01

    Bacterial infections are problematic in many healthcare-associated devices. Antibacterial surfaces integrating the strength of bacteria repellent and bactericidal functions exhibit an encouraging efficacy in tackling this problem. Herein, a hierarchical dual-function antibacterial polymer brush coating that integrates an antifouling bottom layer with a bactericidal top layer is facilely constructed via living photograft polymerization. Excellent resistance to bacterial attachment is correlated with the antifouling components, and good bactericidal activity is afforded by the bactericidal components, and therefore the hierarchical coating shows an excellent long-term antibacterial capability. In addition, due to the presence of the hydrophilic background layer, the hierarchical surface has the greatly improved biocompatibility, as shown by the suppression of platelet adhesion and activation, the inhibition of erythrocyte adhesion and damage, and low toxicity against mammalian cells. The hierarchical polymer brush system provides the basis for the development of long-term antibacterial and biocompatible surfaces.

  2. Antifouling effect of bioactive compounds from selected marine organisms in the Obhur Creek, Red Sea

    NASA Astrophysics Data System (ADS)

    Al-Sofyani, Abdulmohsin; Marimuthu, N.; Wilson, J. Jerald; Pugazhendi, Arulazhagan; Dhavamani, Jeyakumar

    2016-06-01

    Three species of sponges and a tunicate were collected from Obhur creek of Jeddah coast for this bioactivity study. In order to assess the antifouling efficacy of selected marine organisms, methanolic extracts of these organisms were tested against different fouling bacterial forms and II-instar stage of the barnacle, Balanus amphitrite. Antibiosis, bioactivity and followed by multivariate analyses were carried out to check the efficacy of antifouling effect of the selected marine organisms. Principal component analysis revealed the exemplary antifouling efficacy of the sponge extracts of Stylissa sp. observed followed by Hyrtios sp. against bacterial forms in the laboratory study. De-trended correspondence analysis confirmed that the contribution of antifouling efficacy of the selected sponge extracts was observed to be more towards Bacillus sp., Vibrio sp. and Alteromonas sp. Moreover, the efficacy of Hyrtios sp. extract (20.430 μg mL-1) followed by Stylissa sp. (30.945 μg mL-1) showed higher against barnacle instar compared with other extracts in the bioactivity assay. Bray-Curtis cluster analysis under paired linkage categorized all the sponge extracts into one major cluster with 75% similarity, and one outlier tunicate. More than 80% similarity observed between Hyrtios sp. and Stylissa sp. Fourier transform infrared spectroscopy (FTIR) showed that the contribution of major peaks found in the marine organisms were towards sulfones, sulfoxides, cyanates and ketones.

  3. The double effects of silver nanoparticles on the PVDF membrane: Surface hydrophilicity and antifouling performance

    NASA Astrophysics Data System (ADS)

    Li, Jian-Hua; Shao, Xi-Sheng; Zhou, Qing; Li, Mi-Zi; Zhang, Qi-Qing

    2013-01-01

    In this study, silver nanoparticles were used to endow poly(vinylidene fluoride) (PVDF) membrane with excellent surface hydrophilicity and outstanding antifouling performance. Silver nanoparticles were successfully immobilized onto PVDF membrane surface under the presence of poly(acrylic acid) (PAA). The double effects of silver nanoparticles on PVDF membrane, i.e., surface hydrophilicity and anti-fouling performance, were systematically investigated. Judging from result of water static contact measurement, silver nanoparticles had provided a significant improvement in PVDF membrane surface hydrophilicity. And the possible explanation on the improvement of PVDF membrane surface hydrophilicity with silver nanoparticles was firstly proposed in this study. Membrane permeation and anti-bacterial tests were carried out to characterize the antifouling performance of PVDF membrane. Flux recovery ratio (FRR) increased about 40% after the presence of silver nanoparticles on the PVDF membrane surface, elucidating the anti-organic fouling performance of PVDF membrane was elevated by silver nanoparticles. Simultaneously, anti-bacterial test confirmed that PVDF membrane showed superior anti-biofouling activity because of silver nanoparticles. The above-mentioned results clarified that silver nanoparticles can endow PVDF membrane with both excellent surface hydrophilicity and outstanding antifouling performance in this study.

  4. Nacre-inspired design of mechanical stable coating with underwater superoleophobicity.

    PubMed

    Xu, Li-Ping; Peng, Jitao; Liu, Yibiao; Wen, Yongqiang; Zhang, Xueji; Jiang, Lei; Wang, Shutao

    2013-06-25

    Because of the frequent oil spill accidents in marine environment, stable superoleophobic coatings under seawater are highly desired. Current underwater superoleophobic surfaces often suffer from mechanical damages and lose their superoleophobicity gradually. It remains a challenge to fabricate a stable and robust underwater superoleophobic film which can endure harsh conditions in practical application. Nacre is one of most extensively studied rigid biological materials. Inspired by the outstanding mechanical property of seashell nacre and those underwater superoleophobic surfaces from nature, we fabricated a polyelectrolyte/clay hybrid film via typical layer-by-layer (LBL) method based on building blocks with high surface energy. 'Bricks-and-mortar' structure of seashell nacre was conceptually replicated into the prepared film, which endows the obtained film with excellent mechanical property and great abrasion resistance. In addtion, the prepared film also exhibits stable underwater superoleophobicity, low oil adhesion, and outstanding environment durability in artificial seawater. We anticipate that this work will provide a new method to design underwater low-oil-adhesion film with excellent mechanical property and improved stability, which may advance the practical applications in marine antifouling and microfluidic devices.

  5. Inputs of antifouling paint-derived dichlorodiphenyltrichloroethanes (DDTs) to a typical mariculture zone (South China): potential impact on aquafarming environment.

    PubMed

    Yu, Huan-Yun; Shen, Ru-Lang; Liang, Yan; Cheng, Hefa; Zeng, Eddy Y

    2011-12-01

    Existing evidence indicated that dichlorodiphenyltrichloroethane (DDT)-containing antifouling paints were an important source of DDT residues to mariculture zones. However, the magnitude of the impact on aquafarming environment has remained largely unknown. In the present study, the concentrations of DDT and its metabolites (designated as DDXs) were determined in harbor sediment and antifouling paint samples collected from a typical mariculture zone in South China. Compositional and concentration correlation analyses implicated the DDT-containing antifouling paints for fishing boat maintenance as an important source of DDT in the mariculture zone. The annual emission of DDXs to the study region was estimated at 0.58 tons/yr. Furthermore, a comparison of the expected DDT loadings in pelagic fish and field measurements indicated that fish feed especially trash fish was a major source of DDTs in the fish body. Nevertheless, the use of DDT-containing antifouling paints should be limited to prevent further deterioration in aquafarming environment.

  6. Microtopography of the eye surface of the crab Carcinus maenas: an atomic force microscope study suggesting a possible antifouling potential.

    PubMed

    Greco, G; Lanero, T Svaldo; Torrassa, S; Young, R; Vassalli, M; Cavaliere, A; Rolandi, R; Pelucchi, E; Faimali, M; Davenport, J

    2013-07-06

    Marine biofouling causes problems for technologies based on the sea, including ships, power plants and marine sensors. Several antifouling techniques have been applied to marine sensors, but most of these methodologies are environmentally unfriendly or ineffective. Bioinspiration, seeking guidance from natural solutions, is a promising approach to antifouling. Here, the eye of the green crab Carcinus maenas was regarded as a marine sensor model and its surface characterized by means of atomic force microscopy. Engineered surface micro- and nanotopography is a new mechanism found to limit biofouling, promising an effective solution with much reduced environmental impact. Besides giving a new insight into the morphology of C. maenas eye and its characterization, our study indicates that the eye surface probably has antifouling/fouling-release potential. Furthermore, the topographical features of the surface may influence the wettability properties of the structure and its interaction with organic molecules. Results indicate that the eye surface micro- and nanotopography may lead to bioinspired solutions to antifouling protection.

  7. Facile synthesis of novel two-dimensional silver-coated layered double hydroxide nanosheets as advanced anode material for Ni-Zn secondary batteries

    NASA Astrophysics Data System (ADS)

    Yang, Bin; Yang, Zhanhong; Wang, Ruijuan

    2014-04-01

    Silver-coated layered double hydroxide (Ag-coated LDH) nanosheets are successfully prepared by a facile silver mirror reaction and their electrochemical performance has been evaluated as anode materials for Ni-Zn secondary batteries. The microstructure and morphology of as-prepared Ag-coated Zn/Al-LDH are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). As anode material for Ni-Zn secondary batteries, Ag-coated Zn/Al-LDH exhibits high specific capacity (400 mAh g-1), good charge-discharge properties and excellent cycling performance, which is attributed to the effect of the electron conductivity improvement by the Ag coating on the surface of Zn/Al-LDH nanosheet. This newly designed Ag-coated Zn/Al-LDH may offer a promising anode candidate for high-performance Ni-Zn secondary batteries.

  8. An Alternative Low-Cost Process for Deposition of MCrAlY Bond Coats for Advanced Syngas/Hydrogen Turbine Applications

    SciTech Connect

    Zhang, Ying

    2015-09-11

    The objective of this project was to develop and optimize MCrAlY bond coats for syngas/hydrogen turbine applications using a low-cost electrolytic codeposition process. Prealloyed CrAlY-based powders were codeposited into a metal matrix of Ni, Co or Ni-Co during the electroplating process, and a subsequent post-deposition heat treatment converted it to the MCrAlY coating. Our research efforts focused on: (1) investigation of the effects of electro-codeposition configuration and parameters on the CrAlY particle incorporation in the NiCo-CrAlY composite coatings; (2) development of the post-deposition heat treating procedure; (3) characterization of coating properties and evaluation of coating oxidation performance; (4) exploration of a sulfurfree electroplating solution; (5) cost analysis of the present electrolytic codeposition process. Different electro-codeposition configurations were investigated, and the rotating barrel system demonstrated the capability of depositing NiCo-CrAlY composite coatings uniformly on the entire specimen surface, with the CrAlY particle incorporation in the range 37-42 vol.%. Post-deposition heat treatment at 1000-1200 °C promoted interdiffusion between the CrAlY particles and the Ni-Co metal matrix, resulting in β/γ’/γ or β/γ’ phases in the heat-treated coatings. The results also indicate that the post-deposition heat treatment should be conducted at temperatures ≤1100 °C to minimize Cr evaporation and outward diffusion of Ti. The electro-codeposited NiCrAlY coatings in general showed lower hardness and surface roughness than thermal spray MCrAlY coatings. Coating oxidation performance was evaluated at 1000-1100 °C in dry and wet air environments. The initial electro-codeposited NiCoCrAlY coatings containing relatively high sulfur did not show good oxidation resistance. After modifications of the coating process, the cleaner NiCoCrAlY coating exhibited good oxidation performance at 1000 °C during the 2,000 1-h cyclic

  9. Enhancing performance and surface antifouling properties of polysulfone ultrafiltration membranes with salicylate-alumoxane nanoparticles

    NASA Astrophysics Data System (ADS)

    Mokhtari, Samaneh; Rahimpour, Ahmad; Shamsabadi, Ahmad Arabi; Habibzadeh, Setareh; Soroush, Masoud

    2017-01-01

    To improve the hydrophilicity and antifouling properties of polysulfone (PS) ultrafiltration membranes, we studied the use of salicylate-alumoxane (SA) nanoparticles as a novel hydrophilic additive. The effects of SA nanoparticles on the membrane characteristics and performance were investigated in terms of membrane structure, permeation flux, solute rejection, hydrophilicity, and antifouling ability. The new mixed-matrix membranes (MMMs) possess asymmetric structures. They have smaller finger-like pores and smoother surfaces than the neat PS membranes. The embedment of SA nanoparticles in the polymer matrix and the improvement of surface hydrophilicity were investigated. Ultrafiltration experiments indicated that the pure-water flux of the new MMMs initially increases with SA nanoparticles loading followed by a decrease at high loadings. Higher BSA solution flux was achieved for the MMMs compared to the neat PS membranes. Membranes with 1 wt.% SA nanoparticles exhibit the highest flux recovery ratio of 87% and the lowest irreversible fouling of 13%.

  10. Seasonal variation of antifouling activities of marine algae from the Brittany coast (France).

    PubMed

    Hellio, Claire; Marechal, Jean-Philippe; Véron, Benoît; Bremer, Graham; Clare, Anthony S; Le Gal, Yves

    2004-01-01

    The antifouling activity of extracts (aqueous, ethanol, and dichloromethane) of 9 marine macroalgae against bacteria, fungi, diatoms, macroalgal spores, mussel phenoloxidase activity, and barnacle cypris larvae has been investigated in relation to season in bimonthly samples from the Bay of Concarneau (France). Of the extracts tested, 48.2% were active against at least one of the fouling organisms, and of these extracts, 31.2% were seasonally active with a peak of activity in summer corresponding to maximal values for water temperature, light intensity, and fouling pressure, and 17% were active throughout the year. This seasonal activity may be adaptive as it coincides with maximal fouling pressure in the Bay of Concarneau. Dichloromethane extracts of Rhodophyceae were the most active in the antifouling assays.

  11. Differential effects of tributyltin and copper antifoulants on recruitment of non-indigenous species.

    PubMed

    Dafforn, K A; Glasby, T M; Johnston, E L

    2008-01-01

    Maritime transport is a primary vector for many marine invaders. For the past two decades, most commercial vessels have used tributyltin (TBT) antifouling (AF) paint, whereas recreational vessels have been restricted to alternatives, most commonly containing copper. Settlement plates painted with a collar of copper or TBT AF paint, and unpainted control plates, were deployed in commercial and recreational embayments in Port Jackson, Australia, and sampled photographically after 5 and 10 months. Copper enhanced early recruitment of several non-indigenous species (NIS), whereas recruitment of indigenous species was typically reduced by copper. TBT limited the recruitment of NIS for just 5 months and indigenous species, for the entire study. The results suggest that the use of toxic AF paints, and the possible accumulation of AF biocides in embayments, may be negatively affecting indigenous epibiota. Conversely, copper antifoulants on recreational vessels may be facilitating the transport and establishment of copper tolerant NIS into disturbed estuarine habitats.

  12. Accumulation of Cu and Zn in discarded antifouling paint particles by the marine gastropod, Littorina littorea

    NASA Astrophysics Data System (ADS)

    Gammon, Melanie; Turner, Andrew; Brown, Murray T.

    2009-10-01

    The short-term (5 day) accumulation of Cu and Zn in different tissues of the marine gastropod, Littorina littorea, has been studied in the presence of ˜10 mg l -1 of antifouling paint particles and pre- or simultaneously contaminated algal food ( Ulva lactuca). Accumulation of Cu was observed in the head-foot, digestive gland-gonad complex and gills to extents dependent on how and when food was contaminated and administered. However, retention of Zn was only observed in the gills and only when L. littorea and U. lactuca were simultaneously exposed to paint particles. Relative to the alga, faecal material was highly enriched in Zn, suggesting that the animal is able to rapidly eliminate this metal, most likely through the formation and egestion of insoluble phosphate granules. Thus, L. littorea is a useful biomonitor of marine contamination by antifouling applications in respect of Cu but not Zn.

  13. A robust way to prepare blood-compatible and anti-fouling polyethersulfone membrane.

    PubMed

    Xie, Yi; Wang, Rui; Li, Shuangsi; Xiang, Tao; Zhao, Chang-Sheng

    2016-10-01

    Functional copolymers were successfully grafted onto polyethersulfone (PES) membrane surfaces by free radical mechanism using ammonium persulfate (APS) as an initiator. The anti-coagulant and anti-fouling properties of the membranes were well controlled by changing the functional copolymer compositions. Attenuated total reflection-Fourier transforminfrared (ATR-FTIR), X-ray photoelectron spectrometer spectrum (XPS), water contact angles (WCAs), and scanning electron microscopy (SEM) images were used to characterize the membranes. The results of protein adsorption, clotting times, platelet adhesion and bacteria attachment indicated that the membranes had good blood-compatibility and/or anti-fouling ability. Meanwhile, the modification didn't cause an adverse effect on the membrane permeability. This new method provides a general, robust and flexible way to adjust membrane surface performance and potentially has wide applications.

  14. Zwitterionic glycosyl modified polyethersulfone membranes with enhanced anti-fouling property and blood compatibility.

    PubMed

    Xie, Yi; Li, Shuang-Si; Jiang, Xin; Xiang, Tao; Wang, Rui; Zhao, Chang-Sheng

    2015-04-01

    In this study, novel zwitterionic glycosyl modified polyethersulfone (PES) ultrafiltration membranes were prepared via in-situ cross-linking polymerization coupled with phase inversion technique, and the following reactions. The membranes were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), (1)HNMR spectrum, and static water contact angles (WCAs) measurements. The modified membranes showed excellent anti-fouling property, and the flux recovery ratio could reach almost 100%. Meanwhile, the blood compatibility of the membranes was measured by protein adsorption, platelet adhesion, activated partial thromboplastin time (APTT), and thrombin time (TT). The results implied that the zwitterionic glycosyl modified PES membranes had good anti-fouling property and blood compatibility.

  15. A practical ranking system to compare toxicity of anti-fouling paints.

    PubMed

    Karlsson, Jenny; Breitholtz, Magnus; Eklund, Britta

    2006-12-01

    The toxicity of a number of new anti-fouling paints, claimed to function by physical means and not by leakage of toxic substances, have been tested on two common organisms in the Baltic Sea, i.e., the red macro alga Ceramium tenuicorne and the copepod Nitocra spinipes. In order to compare the toxicity between the paints a ranking system was developed based on the EC(50)- and LC(50)-values. The results showed a wide span in toxicity with the most toxic paints ranked 160 times more toxic than the ones ranked least toxic. Also, TBT, irgarol and diuron, which have been used as active ingredients in traditional anti-fouling paints, were used to evaluate the sensitivity of the two test organisms. The results showed that the test organisms were equally sensitive to the substances as similar organisms in earlier studies. In conclusion, the ranking system presented in this study permits ranking and comparison of total toxicity of complex mixtures.

  16. Assessment of organotin and tin-free antifouling paints contamination in the Korean coastal area.

    PubMed

    Lee, Mi-Ri-Nae; Kim, Un-Jung; Lee, In-Seok; Choi, Minkyu; Oh, Jeong-Eun

    2015-10-15

    Twelve organotins (methyl-, octyl-, butyl-, and phenyl-tin), and eight tin-free antifouling paints and their degradation products were measured in marine sediments from the Korean coastal area, and Busan and Ulsan bays, the largest harbor area in Korea. The total concentration of tin-free antifouling paints was two- to threefold higher than the total concentration of organotins. Principal component analysis was used to identify sites with relatively high levels of contamination in the inner bay area of Busan and Ulsan bays, which were separated from the coastal area. In Busan and Ulsan bays, chlorothalonil and DMSA were more dominant than in the coastal area. However, Sea-Nine 211 and total diurons, including their degradation products, were generally dominant in the Korean coastal area. The concentrations of tin and tin-free compounds were significantly different between the east and west coasts.

  17. Production of Depleted UO2Kernels for the Advanced Gas-Cooled Reactor Program for Use in TRISO Coating Development

    SciTech Connect

    Collins, J.L.

    2004-12-02

    The main objective of the Depleted UO{sub 2} Kernels Production Task at Oak Ridge National Laboratory (ORNL) was to conduct two small-scale production campaigns to produce 2 kg of UO{sub 2} kernels with diameters of 500 {+-} 20 {micro}m and 3.5 kg of UO{sub 2} kernels with diameters of 350 {+-} 10 {micro}m for the U.S. Department of Energy Advanced Fuel Cycle Initiative Program. The final acceptance requirements for the UO{sub 2} kernels are provided in the first section of this report. The kernels were prepared for use by the ORNL Metals and Ceramics Division in a development study to perfect the triisotropic (TRISO) coating process. It was important that the kernels be strong and near theoretical density, with excellent sphericity, minimal surface roughness, and no cracking. This report gives a detailed description of the production efforts and results as well as an in-depth description of the internal gelation process and its chemistry. It describes the laboratory-scale gel-forming apparatus, optimum broth formulation and operating conditions, preparation of the acid-deficient uranyl nitrate stock solution, the system used to provide uniform broth droplet formation and control, and the process of calcining and sintering UO{sub 3} {center_dot} 2H{sub 2}O microspheres to form dense UO{sub 2} kernels. The report also describes improvements and best past practices for uranium kernel formation via the internal gelation process, which utilizes hexamethylenetetramine and urea. Improvements were made in broth formulation and broth droplet formation and control that made it possible in many of the runs in the campaign to produce the desired 350 {+-} 10-{micro}m-diameter kernels, and to obtain very high yields.

  18. Laboratory assessment of the antifouling potential of a soluble-matrix paint laced with the natural compound polygodial.

    PubMed

    Cahill, Patrick Louis; Heasman, Kevin; Jeffs, Andrew; Kuhajek, Jeanne

    2013-09-01

    Polygodial is a potent and selective inhibitor of ascidian metamorphosis that shows promise for controlling fouling by ascidians in bivalve aquaculture. The current study examined the potency of, and associated effects of seawater exposure on, a rosin-based soluble-matrix paint laced with 0.08-160 ng polygodial g(-1) wet paint matrix. Paint-coated surfaces were soaked in seawater for 0, 2, 4 or 12 weeks prior to screening for antifouling activity using a bioassay based on the nuisance ascidian Ciona savignyi Herdman. Mortality was greater (mean 50% lethal concentration: 5 ± 2 ng g(-1); mean 75% lethal concentration: 17 ± 4 ng g(-1)) and metamorphosis was inhibited (mean 50% anti-metamorphic concentration: 2 ± 0.4 ng g(-1); mean 75% anti-metamorphic concentration: 15 ± 10 ng g(-1)) in C. savignyi larvae exposed to polygodial-laced soluble-matrix paints, relative to control paints without polygodial. Soaking in seawater prior to testing reduced the efficacy of the formulation up to nearly 12-fold, but even after soaking for 12 weeks paints laced with polygodial at 160 ng g(-1) wet paint matrix prevented ⩾90% of the larvae of C. savignyi from completing metamorphosis. The outcome of this experiment provides a positive first step in evaluating the suitability of polygodial-laced soluble-matrix paints for use in aquaculture.

  19. Development of a novel antifouling platform for biosensing probe immobilization from methacryloyloxyethyl phosphorylcholine-containing copolymer brushes.

    PubMed

    Akkahat, Piyaporn; Kiatkamjornwong, Suda; Yusa, Shin-ichi; Hoven, Voravee P; Iwasaki, Yasuhiko

    2012-04-03

    The immobilization of thiol-terminated poly[(methacrylic acid)-ran-(2-methacryloyloxyethyl phosphorylcholine)] (PMAMPC-SH) brushes on gold-coated surface plasmon resonance (SPR) chips was performed using the "grafting to" approach via self-assembly formation. The copolymer brushes provide both functionalizability and antifouling characteristics, desirable features mandatorily required for the development of an effective platform for probe immobilization in biosensing applications. The carboxyl groups from the methacrylic acid (MA) units were employed for attaching active biomolecules that can act as sensing probes for biospecific detection of target molecules, whereas the 2-methacryloyloxyethyl phosphorylcholine (MPC) units were introduced to suppress unwanted nonspecific adsorption. The detection efficiency of the biotin-immobilized PMAMPC brushes with the target molecule, avidin (AVD), was evaluated in blood plasma in comparison with the conventional 2D monolayer of 11-mercaptoundecanoic acid (MUA) and homopolymer brushes of poly(methacrylic acid) (PMA) also immobilized with biotin using the SPR technique. Copolymer brushes with 79 mol % MPC composition and a molecular weight of 49.3 kDa yielded the platform for probe immobilization with the best performance considering its high S/N ratio as compared with platforms based on MUA and PMA brushes. In addition, the detection limit for detecting AVD in blood plasma solution was found to be 1.5 nM (equivalent to 100 ng/mL). The results have demonstrated the potential for using these newly developed surface-attached PMAMPC brushes for probe immobilization and subsequent detection of designated target molecules in complex matrices such as blood plasma and clinical samples.

  20. Temporal and spatial variation in the fouling of silicone coatings in Pearl Harbor, Hawaii.

    PubMed

    Holm, E R; Nedved, B T; Phillips, N; Deangelis, K L; Hadfield, M G; Smith, C M

    2000-01-01

    An antifouling or foul-release coating cannot be globally effective if it does not perform well in a range of environmental conditions, against a diversity of fouling organisms. From 1996 to 1998, the field test sites participating in the United States Navy's Office of Naval Research 6.2 Biofouling program examined global variation in the performance of 3 silicone foul-release coatings, viz. GE RTV11, Dow Corning RTV 3140, and Intersleek (International Coatings Ltd), together with a control anticorrosive coating (Ameron Protective Coatings F-150 series). At the University of Hawaii's test site in Pearl Harbor, significant differences were observed among the coatings in the rate of accumulation of fouling. The control coating failed rapidly; after 180-220 d immersion a community dominated by molluscs and sponges developed that persisted for the remainder of the experiment. Fouling of the GE and Dow Corning silicone coatings was slower, but eventually reached a similar community structure and coverage as the control coatings. The Intersleek coating remained lightly fouled throughout the experiment. Spatial variation in the structure of the community fouling the coatings was observed, but not in the extent of fouling. The rate of accumulation of fouling reflected differences among the coatings in adhesion of the tubeworm Hydroides elegans. The surface properties of these coatings may have affected the rate of fouling and the structure of the fouling community through their influence on larval settlement and subsequent interactions with other residents, predators, and the physical environment.

  1. Effect of film thickness on the antifouling performance of poly(hydroxy-functional methacrylates) grafted surfaces.

    PubMed

    Zhao, Chao; Li, Lingyan; Wang, Qiuming; Yu, Qiuming; Zheng, Jie

    2011-04-19

    The development of nonfouling biomaterials to prevent nonspecific protein adsorption and cell/bacterial adhesion is critical for many biomedical applications, such as antithrombogenic implants and biosensors. In this work, we polymerize two types of hydroxy-functional methacrylates monomers of 2-hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPMA) into polymer brushes on the gold substrate via surface-initiated atom transfer radical polymerization (SI-ATRP). We systematically examine the effect of the film thickness of polyHEMA and polyHPMA brushes on their antifouling performance in a wide range of biological media including single-protein solution, both diluted and undiluted human blood serum and plasma, and bacteria culture. Surface plasmon resonance (SPR) results show a strong correlation between antifouling property and film thickness. Too thin or too thick polymer brushes lead to large protein adsorption. Surfaces with the appropriate film thickness of ∼25-45 nm for polyHPMA and ∼20-45 nm for polyHEMA can achieve almost zero protein adsorption (<0.3 ng/cm(2)) from single-protein solution and diluted human blood plasma and serum. For undiluted human blood serum and plasma, polyHEMA brushes at a film thickness of ∼20-30 nm adsorb only ∼3.0 and ∼3.5 ng/cm(2) proteins, respectively, while polyHPMA brushes at a film thickness of ∼30 nm adsorb more proteins of ∼13.5 and ∼50.0 ng/cm(2), respectively. Moreover, both polyHEMA and polyHPMA brushes with optimal film thickness exhibit very low bacteria adhesion. The excellent antifouling ability and long-term stability of polyHEMA and polyHPMA brushes make them, especially for polyHEMA, effective and stable antifouling materials for usage in blood-contacting devices.

  2. High-Performance Corrosion-Resistant Materials: Iron-Based Amorphous-Metal Thermal-Spray Coatings: SAM HPCRM Program ? FY04 Annual Report ? Rev. 0 - DARPA DSO & DOE OCRWM Co-Sponsored Advanced Materials Program

    SciTech Connect

    Farmer, J; Haslam, J; Wong, F; Ji, S; Day, S; Branagan, D; Marshall, M; Meacham, B; Buffa, E; Blue, C; Rivard, J; Beardsley, M; Buffa, E; Blue, C; Rivard, J; Beardsley, M; Weaver, D; Aprigliano, L; Kohler, L; Bayles, R; Lemieux, E; Wolejsza, T; Martin, F; Yang, N; Lucadamo, G; Perepezko, J; Hildal, K; Kaufman, L; Heuer, A; Ernst, F; Michal, G; Kahn, H; Lavernia, E

    2007-09-19

    The multi-institutional High Performance Corrosion Resistant Materials (HPCRM) Team is cosponsored by the Defense Advanced Projects Agency (DARPA) Defense Science Office (DSO) and the Department of Energy (DOE) Office of Civilian Radioactive Waste Management (OCRWM), and has developed new corrosion-resistant, iron-based amorphous metals that can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Corrosion costs the Department of Defense billions of dollars every year, with an immense quantity of material in various structures undergoing corrosion. For example, in addition to fluid and seawater piping, ballast tanks, and propulsions systems, approximately 345 million square feet of structure aboard naval ships and crafts require costly corrosion control measures. The use of advanced corrosion-resistant materials to prevent the continuous degradation of this massive surface area would be extremely beneficial. The Fe-based corrosion-resistant, amorphous-metal coatings under development may prove of importance for applications on ships. Such coatings could be used as an 'integral drip shield' on spent fuel containers, as well as protective coatings that could be applied over welds, thereby preventing exposure to environments that might cause stress corrosion cracking. In the future, such new high-performance iron-based materials could be substituted for more-expensive nickel-based alloys, thereby enabling a reduction in the $58-billion life cycle cost for the long-term storage of the Nation's spent nuclear fuel by tens of percent.

  3. Surface modification of silicone for biomedical applications requiring long-term antibacterial, antifouling, and hemocompatible properties.

    PubMed

    Li, Min; Neoh, Koon Gee; Xu, Li Qun; Wang, Rong; Kang, En-Tang; Lau, Titus; Olszyna, Dariusz Piotr; Chiong, Edmund

    2012-11-27

    Silicone has been used for peritoneal dialysis (PD) catheters for several decades. However, bacteria, platelets, proteins, and other biomolecules tend to adhere to its hydrophobic surface, which may lead to PD outflow failure, serious infection, or even death. In this work, a cross-linked poly(poly(ethylene glycol) dimethacrylate) (P(PEGDMA)) polymer layer was covalently grafted on medical-grade silicone surface to improve its antibacterial and antifouling properties. The P(PEGDMA)-grafted silicone (Silicone-g-P(PEGDMA)) substrate reduced the adhesion of Staphylococcus aureus , Escherichia coli , and Staphylococcus epidermidis , as well as 3T3 fibroblast cells by ≥90%. The antibacterial and antifouling properties were preserved after the modified substrate was aged for 30 days in phosphate buffer saline. Further immobilization of a polysulfobetaine polymer, poly((2-(methacryloyloxy)ethyl)dimethyl-(3-sulfopropyl)ammonium hydroxide) (P(DMAPS)), on the Silicone-g-P(PEGDMA) substrate via thiol-ene click reaction leads to enhanced antifouling efficacy and improved hemocompatibility with the preservation of the antibacterial property. Compared to pristine silicone, the so-obtained Silicone-g-P(PEGDMA)-P(DMAPS) substrate reduced the absorption of bovine serum albumin and bovine plasma fibrinogen by ≥80%. It also reduced the number of adherent platelets by ≥90% and significantly prolonged plasma recalcification time. The results indicate that surface grafting with P(PEGDMA) and P(DMAPS) can be potentially useful for the modification of silicone-based PD catheters for long-term applications.

  4. Development of an electrochemical antifouling system for seawater cooling pipelines of power plants using titanium.

    PubMed

    Wake, Hitoshi; Takahashi, Hiromichi; Takimoto, Toshihiro; Takayanagi, Hirokazu; Ozawa, Kinichi; Kadoi, Hideo; Okochi, Mina; Matsunaga, Tadashi

    2006-10-20

    Biofouling is the undesirable adhesion and development of microorganisms and macroorganisms in a water environment. An electrochemical antifouling system based on management of primary adhesion of microorganisms was developed employing titanium electrode for antifouling of seawater cooling pipes and marine infrastructures. The system consists of an electrochemical reaction-monitoring unit, a power control unit, and a potential/current remote monitoring and a control unit. Titanium plates and iron plates were used as the working and counter electrode, respectively. Field experiment was conducted in the seawater cooling pipeline system of a thermal power station. Four titanium electrodes with 1.0 m length and 3.0 m width were set in the seawater intake pit and current density was controlled at 50-100 mA/m(2). The electrode surface maintained clean conditions for 2 years. The average wet weight of fouling organisms on the titanium electrode surface was below 100 g/m(2) whereas the corresponding wet weight was above 10 kg/m(2) on the control surface. Using titanium as the electrode material, chlorine and hypochlorite are not generated. The developed electrochemical antifouling system provided an effective, environmentally friendly, and feasible techniques for remote operations.

  5. Preparation and antifouling property of polyurethane film modified by chondroitin sulfate

    NASA Astrophysics Data System (ADS)

    Yuan, Huihui; Xue, Jing; Qian, Bin; Chen, Huaying; Zhu, Yonggang; Lan, Minbo

    2017-02-01

    An antifouling polyurethane film modified by chondroitin sulfate (PU-CS) was prepared by chemical grafting with N-Boc-1,3-propanediamine as a spacer. The different mass fraction of N-Boc-1,3-propanediamine was investigated to obtain PU-CS films with different CS grafting density. The surface properties of PU-CS films were comprehensively characterized. Proteins adsorption and glycosaminoglycans adhesion on films were evaluated. Moreover, inorganic salt deposition on film with highest CS grafting density (3.70 μg/cm2) was briefly investigated. The results showed that the increase of CS grafting density improved not only the hydrophilicity but the antifouling performance of films. The best antifouling film reduced the adsorption of fibrinogen (BFG), human serum albumin (HSA) and lysozyme (LYS) by 81.4%, 95.0% and 76.5%, respectively, and the adhesion of chondroitin (CS), heparin (HP) and hyaluronic acid (HA) by 70.6%, 87.4% and 81.3%, respectively. In addition, the co-adsorption of proteins and glycosaminoglycans reduced up to 86.9% and 75.5%, respectively. Changes in inorganic salt deposition after co-adsorption of proteins and glycosaminoglycans on PU-CS(3) suggested that the proteins promoted the inorganic salt deposition, while glycosaminoglycans inhibited the crystal growth. The negatively charged polysaccharides might promote the generation of smaller crystals which could be conducive to provide theoretical and practical guide to develop novel urinary stents with significant anti-encrustation properties.

  6. Efficient wastewater treatment by membranes through constructing tunable antifouling membrane surfaces.

    PubMed

    Chen, Wenjuan; Su, Yanlei; Peng, Jinming; Zhao, Xueting; Jiang, Zhongyi; Dong, Yanan; Zhang, Yan; Liang, Yangui; Liu, Jiazhen

    2011-08-01

    In the present study, a facile in situ approach for constructing tunable amphiphilic or hydrophilic antifouling membrane surfaces was demonstrated by exquisitely manipulating the microphase separation and surface segregation behavior of the tailor-made ternary amphiphilic block copolymers during the commonly utilized wet phase inversion membrane-formation process. Under dead-end filtration for oily wastewater treatment, the membrane with amphiphilic surface exhibited over 99.5% retention ratio of chemical oxygen demand (COD) without appreciable membrane fouling: the water permeation flux was slightly decreased during operation (total flux decline was 6.8%) and almost completely recovered to the initial value (flux recovery ratio was more than 99.0%) after simple hydraulic washing. While for the proteins-containing wastewater treatment, the membrane with hydrophilic surface exhibited about 52.6% COD retention ratio and superior antifouling performance: only 17.0% total flux decline and also more than 99.0% flux recovery ratio. Hopefully, the present approach can be developed as a competitive platform technology for the preparation of robust and versatile antifouling membrane, leading to the high process efficiency of wastewater treatments.

  7. Antifouling Block Copolymer Surfaces that Resist Settlement of Barnacle Larvae

    SciTech Connect

    Weinman,C.; Krishnan, S.; Park, D.; Paik, M.; Wong, K.; Fischer, D.; Handlin, D.; Kowalke, G.; Wendt, D.; et al

    2007-01-01

    Marine biofouling is a serious problem caused by the accumulation and settlement of barnacles, macroalgae, and microbial slimes on the hulls of seafaring vessels. Biofouling can significantly increase drag, leading to startling consequences with regards to fuel consumption. Environmentally compatible solutions to biofouling are being sought as traditional metal-based systems of fouling control are being phased out due to their inherent toxicity. Further exasperating the problem of biofouling is the vast range of fouling organisms and environmental conditions experienced throughout the world. This renders the development of a universal biofouling coating a significant challenge.

  8. Tribology and coatings

    SciTech Connect

    1995-06-01

    The future use of fuel-efficient, low-emission, advanced transportation systems (for example, those using low-heat-rejection diesel engines or advanced gas turbines) presents new challenges to tribologists and materials scientists. High service temperatures, corrosive environments, and extreme contact pressures are among the concerns that make necessary new tribological designs, novel materials, and effective lubrication concepts. Argonne is working on methods to reduce friction, wear and corrosion, such as soft metal coatings on ceramics, layered compounds, diamond coatings, and hard surfaces.

  9. Low Conductivity Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming

    2005-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and requirements will be discussed. An experimental approach is established to monitor in real time the thermal conductivity of the coating systems subjected to high-heat-flux, steady-state and cyclic temperature gradients. Advanced low conductivity thermal barrier coatings have also been developed using a multi-component defect clustering approach, and shown to have improved thermal stability. The durability and erosion resistance of low conductivity thermal barrier coatings have been improved utilizing advanced coating architecture design, composition optimization, in conjunction with more sophisticated modeling and design tools.

  10. Advanced process control and novel test methods for PVD silicon and elastomeric silicone coatings utilized on ion implant disks, heatsinks and selected platens

    NASA Astrophysics Data System (ADS)

    Springer, J.; Allen, B.; Wriggins, W.; Kuzbyt, R.; Sinclair, R.

    2012-11-01

    Coatings play multiple key roles in the proper functioning of mature and current ion implanters. Batch and serial implanters require strategic control of elemental and particulate contamination which often includes scrutiny of the silicon surface coatings encountering direct beam contact. Elastomeric Silicone Coatings must accommodate wafer loading and unloading as well as direct backside contact during implant plus must maintain rigid elemental and particulate specifications. The semiconductor industry has had a significant and continuous effort to obtain ultra-pure silicon coatings with sustained process performance and long life. Low particles and reduced elemental levels for silicon coatings are a major requirement for process engineers, OEM manufacturers, and second source suppliers. Relevant data will be presented. Some emphasis and detail will be placed on the structure and characteristics of a relatively new PVD Silicon Coating process that is very dense and homogeneous. Wear rate under typical ion beam test conditions will be discussed. The PVD Silicon Coating that will be presented here is used on disk shields, wafer handling fingers/fences, exclusion zones of heat sinks, beam dumps and other beamline components. Older, legacy implanters can now provide extended process capability using this new generation PVD silicon - even on implanter systems that were shipped long before the advent of silicon coating for contamination control. Low particles and reduced elemental levels are critical performance criteria for the silicone elastomers used on disk heatsinks and serial implanter platens. Novel evaluation techniques and custom engineered tools are used to investigate the surface interaction characteristics of multiple Elastomeric Silicone Coatings currently in use by the industry - specifically, friction and perpendicular stiction. These parameters are presented as methods to investigate the critical wafer load and unload function. Unique tools and test

  11. Advanced process control and novel test methods for PVD silicon and elastomeric silicone coatings utilized on ion implant disks, heatsinks and selected platens

    SciTech Connect

    Springer, J.; Allen, B.; Wriggins, W.; Kuzbyt, R.; Sinclair, R.

    2012-11-06

    Coatings play multiple key roles in the proper functioning of mature and current ion implanters. Batch and serial implanters require strategic control of elemental and particulate contamination which often includes scrutiny of the silicon surface coatings encountering direct beam contact. Elastomeric Silicone Coatings must accommodate wafer loading and unloading as well as direct backside contact during implant plus must maintain rigid elemental and particulate specifications. The semiconductor industry has had a significant and continuous effort to obtain ultra-pure silicon coatings with sustained process performance and long life. Low particles and reduced elemental levels for silicon coatings are a major requirement for process engineers, OEM manufacturers, and second source suppliers. Relevant data will be presented. Some emphasis and detail will be placed on the structure and characteristics of a relatively new PVD Silicon Coating process that is very dense and homogeneous. Wear rate under typical ion beam test conditions will be discussed. The PVD Silicon Coating that will be presented here is used on disk shields, wafer handling fingers/fences, exclusion zones of heat sinks, beam dumps and other beamline components. Older, legacy implanters can now provide extended process capability using this new generation PVD silicon - even on implanter systems that were shipped long before the advent of silicon coating for contamination control. Low particles and reduced elemental levels are critical performance criteria for the silicone elastomers used on disk heatsinks and serial implanter platens. Novel evaluation techniques and custom engineered tools are used to investigate the surface interaction characteristics of multiple Elastomeric Silicone Coatings currently in use by the industry - specifically, friction and perpendicular stiction. These parameters are presented as methods to investigate the critical wafer load and unload function. Unique tools and test

  12. Biofouling of Cr-Nickel Spray Coated Films on Steel Surfaces

    NASA Astrophysics Data System (ADS)

    Yoshida, Kento; Kanematsu, Hideyuki; Kuroda, Daisuke; Ikigai, Hajime; Kogo, Takeshi; Yokoyama, Seiji

    2012-03-01

    , the former showed higher antifouling properties generally. Aluminium-zinc alloy spray coated films had higher antifouling property. And the anti-property decreased in this order: Al-Zn alloy spray coating > Zinc spray coating > Aluminium spray coating > Stacked chromium/nickel spray coating. Aluminium and zinc spray coating has been evaluated high conventionally for anti-biofouling in marine environment. However, the Cr/Ni spray coating showed pretty high anti-fouling property.

  13. Aluminide coatings

    SciTech Connect

    Henager, Jr; Charles, H; Shin, Yongsoon; Samuels, William D

    2009-08-18

    Disclosed herein are aluminide coatings. In one embodiment coatings are used as a barrier coating to protect a metal substrate, such as a steel or a superalloy, from various chemical environments, including oxidizing, reducing and/or sulfidizing conditions. In addition, the disclosed coatings can be used, for example, to prevent the substantial diffusion of various elements, such as chromium, at elevated service temperatures. Related methods for preparing protective coatings on metal substrates are also described.

  14. COATED ALLOYS

    DOEpatents

    Harman, C.G.; O'Bannon, L.S.

    1958-07-15

    A coating is described for iron group metals and alloys, that is particularly suitable for use with nickel containing alloys. The coating is glassy in nature and consists of a mixture containing an alkali metal oxide, strontium oxide, and silicon oxide. When the glass coated nickel base metal is"fired'' at less than the melting point of the coating, it appears the nlckel diffuses into the vitreous coating, thus providing a closely adherent and protective cladding.

  15. Zwitterionic polymer functionalization of polysulfone membrane with improved antifouling property and blood compatibility by combination of ATRP and click chemistry.

    PubMed

    Xiang, Tao; Lu, Ting; Xie, Yi; Zhao, Wei-Feng; Sun, Shu-Dong; Zhao, Chang-Sheng

    2016-08-01

    The chemical compositions are very important for designing blood-contacting membranes with good antifouling property and blood compatibility. In this study, we propose a method combining ATRP and click chemistry to introduce zwitterionic polymer of poly(sulfobetaine methacrylate) (PSBMA), negatively charged polymers of poly(sodium methacrylate) (PNaMAA) and/or poly(sodium p-styrene sulfonate) (PNaSS), to improve the antifouling property and blood compatibility of polysulfone (PSf) membranes. Attenuated total reflectance-Fourier transform infrared spectra, X-ray photoelectron spectroscopy and water contact angle results confirmed the successful grafting of the functional polymers. The antifouling property and blood compatibility of the modified membranes were systematically investigated. The zwitterionic polymer (PSBMA) grafted membranes showed good resistance to protein adsorption and bacterial adhesion; the negatively charged polymer (PNaSS or PNaMAA) grafted membranes showed improved blood compatibility, especially the anticoagulant property. Moreover, the PSBMA/PNaMAA modified membrane showed both antifouling property and anticoagulant property, and exhibited a synergistic effect in inhibiting blood coagulation. The functionalization of membrane surfaces by a combination of ATRP and click chemistry is demonstrated as an effective route to improve the antifouling property and blood compatibility of membranes in blood-contact.

  16. Proceedings of the DARPA (Defense Advanced Research Projects Agency) Workshop on Diamond-Like Carbon Coatings, held at Albuquerque, New Mexico on April 19-20, 1982,

    DTIC Science & Technology

    1982-01-01

    structural models proposed for a-C. Diffraction methods appear to be capable of giving very precise answers if the data are obtained out to sufficiently viii...Fundamental Questions (a) sp3 vs sp2 bonding (b) Intrinsic vs extrinsic absorption (c) Coating microstructure, amorphousness vs polycrystallinity (d) Role...deposition methods (g) Role of implantation, surface cleaning and surface conditioning 2 "e ..:..:. Priority DoD Applications (a) AR coatings for 8-12 um low

  17. Advanced Zinc Phosphate Conversion and Pre-Ceramic Polymetallosiloxane Coatings for Corrosion Protection of Steel and Aluminum, and Characteristics of Polyphenyletheretherketone-Based Materials

    DTIC Science & Technology

    1992-09-24

    thermal de- composition, phase transformation, and pyrolys - T. Sitgama et al. / Pymgenic polygerrnunostloxane text titles for aluminum subsiraics is...converted into a sintered coating film by pre-heating in air at 100"C and then annealing at 300 C to form the pyrolysed PTS film. Simple dip-coating...XRD study was considered necessary to determine whether the pyrolysed materials had crystallized. Fig. 5 represents the XRD patterns of the 350 C

  18. Active coatings technologies for tailorable military coating systems

    NASA Astrophysics Data System (ADS)

    Zunino, J. L., III

    2007-04-01

    The main objective of the U.S. Army's Active Coatings Technologies Program is to develop technologies that can be used in combination to tailor coatings for utilization on Army Materiel. The Active Coatings Technologies Program, ACT, is divided into several thrusts, including the Smart Coatings Materiel Program, Munitions Coatings Technologies, Active Sensor packages, Systems Health Monitoring, Novel Technology Development, as well as other advanced technologies. The goal of the ACT Program is to conduct research leading to the development of multiple coatings systems for use on various military platforms, incorporating unique properties such as self repair, selective removal, corrosion resistance, sensing, ability to modify coatings' physical properties, colorizing, and alerting logistics staff when tanks or weaponry require more extensive repair. A partnership between the U.S. Army Corrosion Office at Picatinny Arsenal, NJ along with researchers at the New Jersey Institute of Technology, NJ, Clemson University, SC, University of New Hampshire, NH, and University of Massachusetts (Lowell), MA, are developing the next generation of Smart Coatings Materiel via novel technologies such as nanotechnology, Micro-electromechanical Systems (MEMS), meta-materials, flexible electronics, electrochromics, electroluminescence, etc. This paper will provide the reader with an overview of the Active Coatings Technologies Program, including an update of the on-going Smart Coatings Materiel Program, its progress thus far, description of the prototype Smart Coatings Systems and research tasks as well as future nanotechnology concepts, and applications for the Department of Defense.

  19. Effects of Antifouling Biocides on Molecular and Biochemical Defense System in the Gill of the Pacific Oyster Crassostrea gigas

    PubMed Central

    Park, Mi Seon; Kim, Young Dae; Kim, Bo-Mi; Kim, Youn-Jung; Kim, Jang Kyun; Rhee, Jae-Sung

    2016-01-01

    Antifouling biocides such as organotin compounds and their alternatives are potent toxicants in marine ecosystems. In this study, we employed several molecular and biochemical response systems of the Pacific oyster Crassostrea gigas to understand a potential mode of action of antifouling biocides (i.e. tributyltin (TBT), diuron and irgarol) after exposure to different concentrations (0.01, 0.1, and 1 μg L-1) for 96 h. As a result, all the three antifouling biocides strongly induced the antioxidant defense system. TBT reduced both enzymatic activity and mRNA expression of Na+/K+-ATPase and acetylcholinesterase (AChE). Lower levels of both Na+/K+-ATPase activity and AChE mRNA expression were observed in the diuron-exposed oysters compared to the control, while the irgarol treatment reduced only the transcriptional expression of AChE gene. We also analyzed transcript profile of heat shock protein (Hsp) superfamily in same experimental conditions. All antifouling biocides tested in this study significantly modulated mRNA expression of Hsp superfamily with strong induction of Hsp70 family. Taken together, overall results indicate that representative organotin TBT and alternatives have potential hazardous effects on the gill of C. gigas within relatively short time period. Our results also suggest that analyzing a series of molecular and biochemical parameters can be a way of understanding and uncovering the mode of action of emerging antifouling biocides. In particular, it was revealed that Pacific oysters have different sensitivities depend on the antifouling biocides. PMID:28006823

  20. Cermet composite thermal spray coatings for erosion and corrosion protection in combustion environments of advanced coal-fired boilers. Semiannual technical report, January 14, 1997--August 14, 1997

    SciTech Connect

    Schorr, B.S.; Levin, B.F.; DuPont, J.N.; Marder, A.R.

    1997-08-31

    Research is presently being conducted to determine the optimum ceramic/metal combination in thermally sprayed metal matrix composite coatings for erosion and corrosion resistance in new coal-fired boilers. The research will be accomplished by producing model cermet composites using powder metallurgy and electrodeposition methods in which the effect of ceramic/metal combination for the erosion and corrosion resistance will be determined. These results will provide the basis for determining the optimum hard phase constituent size and volume percent in thermal spray coatings. Thermal spray coatings will be applied by our industrial sponsor and tested in our erosion and corrosion laboratories. Bulk powder processed Ni-Al{sub 2}O{sub 3} composites were produced at Idaho National Engineering Laboratory. The composite samples contained 0, 21, 27, 37, and 45 volume percent Al{sub 2}O{sub 3} with an average particle size of 12 um. Also, to deposit model Ni-Al{sub 2}O{sub 3} coatings, an electrodeposition technique was developed and coatings with various volume fractions (0-35%) of Al{sub 2}O{sub 3} were produced. The powder and electrodeposition processing of Ni-Al{sub 2}O{sub 3} Composites provide the ability to produce two phase microstructure without changing the microstructure of the matrix material. Therefore, the effect of hard second phase particles size and volume fraction on erosion resistance could be analyzed.

  1. Library of Antifouling Surfaces Derived From Natural Amino Acids by Click Reaction.

    PubMed

    Xu, Chen; Hu, Xin; Wang, Jie; Zhang, Ye-Min; Liu, Xiao-Jiu; Xie, Bin-Bin; Yao, Chen; Li, Yi; Li, Xin-Song

    2015-08-12

    Biofouling is of great concern in numerous applications ranging from ophthalmological implants to catheters, and from bioseparation to biosensors. In this report, a general and facile strategy to combat surface fouling is developed by grafting of amino acids onto polymer substrates to form zwitterionic structure through amino groups induced epoxy ring opening click reaction. First of all, a library of poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) hydrogels with zwitterionic surfaces were prepared, resulting in the formation of pairs of carboxyl anions and protonated secondary amino cations. The analysis of attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the successful immobilization of amino acids on the hydrogel surfaces. After that, the contact angle and equilibrium water content of the modified hydrogels showed that the hydrogels exhibited improved hydrophilicity compared with the parent hydrogel. Furthermore, the protein deposition was evaluated by bicinchoninic acid assay using bovine serum albumin (BSA) and lysozyme as models. The results indicated that the performance of the hydrogels was determined by the nature of incorporated amino acid: the hydrogels incorporated with neutral amino acids had nonspecific antiadsorption capability to both BSA and lysozyme; the hydrogels incorporated with charged amino acids showed antiadsorption behaviors against protein with same charge and enhanced adsorption to the protein with opposite charge; the optimal antiadsorption performance was observed on the hydrogels incorporated with polar amino acids with a hydroxyl residual. The improvement of antiprotein fouling of the neutral amino acids grafted hydrogels can be ascribed to the formation of zwitterionic surfaces. Finally, a couple of soft contact lenses grafted with amino acids were fabricated having improved antifouling property and hydrophilicity. The result demonstrated the success of

  2. A New, Sensitive Marine Microalgal Recombinant Biosensor Using Luminescence Monitoring for Toxicity Testing of Antifouling Biocides

    PubMed Central

    Sanchez-Ferandin, Sophie; Leroy, Fanny; Bouget, François-Yves

    2013-01-01

    In this study, we propose the use of the marine green alga Ostreococcus tauri, the smallest free-living eukaryotic cell known to date, as a new luminescent biosensor for toxicity testing in the environment. Diuron and Irgarol 1051, two antifouling biocides commonly encountered in coastal waters, were chosen to test this new biosensor along with two degradation products of diuron. The effects of various concentrations of the antifoulants on four genetic constructs of O. tauri (based on genes involved in photosynthesis, cell cycle, and circadian clock) were compared using 96-well culture microplates and a luminometer to automatically measure luminescence over 3 days. This was compared to growth inhibition of O. tauri wild type under the same conditions. Luminescence appeared to be more sensitive than growth inhibition as an indicator of toxicity. Cyclin-dependent kinase (CDKA), a protein involved in the cell cycle, fused to luciferase (CDKA-Luc) was found to be the most sensitive of the biosensors, allowing an accurate determination of the 50% effective concentration (EC50) after only 2 days (diuron, 5.65 ± 0.44 μg/liter; Irgarol 1015, 0.76 ± 0.10 μg/liter). The effects of the antifoulants on the CDKA-Luc biosensor were then compared to growth inhibition in natural marine phytoplankton. The effective concentrations of diuron and Irgarol 1051 were found to be similar, indicating that this biosensor would be suitable as a reliable ecotoxicological test. The advantage of this biosensor over cell growth inhibition testing is that the process can be easily automated and could provide a high-throughput laboratory approach to perform short-term toxicity tests. The ability to genetically transform and culture recombinant O. tauri gives it huge potential for screening many other toxic compounds. PMID:23144143

  3. Preparation of PES ultrafiltration membranes with natural amino acids based zwitterionic antifouling surfaces

    NASA Astrophysics Data System (ADS)

    Xu, Chen; Liu, Xiaojiu; Xie, Binbin; Yao, Chen; Hu, Wenhan; Li, Yi; Li, Xinsong

    2016-11-01

    In this report, a simple and facile approach to enhance the antifouling property of poly(ether sulfone) (PES) ultrafiltration membrane was developed by grafting natural amino acids onto surface. First of all, poly(ether sulfone) composite membranes blended with poly(glycidyl methacrylate) were fabricated by phase inversion method followed by grafting of different types of natural amino acids onto the membrane surface through epoxy ring opening reaction. The analysis of attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FTIR) and X-ray photoelectron spectroscopy (XPS) verified the substantial enrichment of amino acids onto the surface of PES membranes. The hydrophilicity of the PES membranes was improved after grafting amino acids. The mechanical property and morphologies of the PES membranes proved that their basic performances were not obviously affected by grafting reaction, and these parameters were all still in the typical range for ultrafiltration membranes. The antifouling property of the grafted PES membranes against bovine serum albumin (BSA) and lysozyme (Lyz) was investigated in detail. It was found that PES membranes incorporated with neutral amino acids exhibited higher fouling resistance to both BSA and Lyz than the parent PES membrane. It can be ascribed to the formation of zwitterionic structure on the surface consisting of protonated secondary amino cations and carboxyl anions. Meanwhile, PES membranes grafted with charged amino acids had better antifouling properties against protein with same electric charges and improved adsorption related to protein with opposite electric charges. Furthermore, the ultrafiltration performance of the zwitterionic PES membranes was evaluated. The results showed that the modified membranes possessed of enhanced pure water flux, relative flux recovery and mildly lower rejection. The Darcy's Law analysis illustrated that the acidic amino acid grafted PES membranes had much lower permeation

  4. Optimisation and Characterisation of Anti-Fouling Ternary SAM Layers for Impedance-Based Aptasensors.

    PubMed

    Miodek, Anna; Regan, Edward M; Bhalla, Nikhil; Hopkins, Neal A E; Goodchild, Sarah A; Estrela, Pedro

    2015-09-29

    An aptasensor with enhanced anti-fouling properties has been developed. As a case study, the aptasensor was designed with specificity for human thrombin. The sensing platform was developed on screen printed electrodes and is composed of a self-assembled monolayer made from a ternary mixture of 15-base thiolated DNA aptamers specific for human thrombin co-immobilised with 1,6-hexanedithiol (HDT) and further passivated with 1-mercapto-6-hexanol (MCH). HDT binds to the surface by two of its thiol groups forming alkyl chain bridges and this architecture protects from non-specific attachment of molecules to the electrode surface. Using Electrochemical Impedance Spectroscopy (EIS), the aptasensor is able to detect human thrombin as variations in charge transfer resistance (Rct) upon protein binding. After exposure to a high concentration of non-specific Bovine Serum Albumin (BSA) solution, no changes in the Rct value were observed, highlighting the bio-fouling resistance of the surface generated. In this paper, we present the optimisation and characterisation of the aptasensor based on the ternary self-assembled monolayer (SAM) layer. We show that anti-fouling properties depend on the type of gold surface used for biosensor construction, which was also confirmed by contact angle measurements. We further studied the ratio between aptamers and HDT, which can determine the specificity and selectivity of the sensing layer. We also report the influence of buffer pH and temperature used for incubation of electrodes with proteins on detection and anti-fouling properties. Finally, the stability of the aptasensor was studied by storage of modified electrodes for up to 28 days in different buffers and atmospheric conditions. Aptasensors based on ternary SAM layers are highly promising for clinical applications for detection of a range of proteins in real biological samples.

  5. Antifouling properties of tough gels against barnacles in a long-term marine environment experiment.

    PubMed

    Murosaki, T; Noguchi, T; Hashimoto, K; Kakugo, A; Kurokawa, T; Saito, J; Chen, Y M; Furukawa, H; Gong, J P

    2009-10-01

    In the marine environment, the antifouling (AF) properties of various kinds of hydrogels against sessile marine organisms (algae, sea squirts, barnacles) were tested in a long-term experiment. The results demonstrate that most hydrogels can endure at least 2 months in the marine environment. In particular, mechanically tough PAMPS/PAAm DN and PVA gels exhibited AF activity against marine sessile organisms, especially barnacles, for as long as 330 days. The AF ability of hydrogels toward barnacles is explained in terms of an 'easy-release' mechanism in which the high water content and the elastic modulus of the gel are two important parameters.

  6. Embryotoxicity of the antifouling biocide zinc pyrithione to sea urchin (Paracentrotus lividus) and mussel (Mytilus edulis).

    PubMed

    Bellas, Juan; Granmo, Ke; Beiras, Ricardo

    2005-11-01

    The effects of the new antifouling compound zinc pyrithione (Zpt) on the embryonic development of sea urchin (Paracentrotus lividus) and mussel (Mytilus edulis) were investigated in laboratory toxicity tests. The median effective concentrations (EC50) were 7.7 nM for sea urchin embryos and 8 nM for mussel embryos. Toxic effects of Zpt on the larval growth of the sea urchin were detected at 0.5 nM. Predicted environmental concentrations of Zpt in pleasure craft harbours are higher than the predicted no effect concentrations for sea urchin and mussel embryos, indicating that Zpt may pose a threat to those species from exposure in the field.

  7. Use of thiolated oligonucleotides as anti-fouling diluents in electrochemical peptide-based sensors.

    PubMed

    McQuistan, Adam; Zaitouna, Anita J; Echeverria, Elena; Lai, Rebecca Y

    2014-05-11

    We incorporated short thiolated oligonucleotides as passivating diluents in the fabrication of electrochemical peptide-based (E-PB) sensors, with the goal of creating a negatively charged layer capable of resisting non-specific adsorption of matrix contaminants. The E-PB HIV sensors fabricated using these diluents were found to be more specific and selective, while retaining attributes similar to the sensor fabricated without these diluents. Overall, these results highlight the advantages of using oligonucleotides as anti-fouling diluents in self-assembled monolayer-based sensors.

  8. Toxicity of anti-fouling biocides to Parorchis acanthus (Digenea: Philophthalmidae) cercarial encystment.

    PubMed

    Morley, N J; Leung, K M Y; Morritt, D; Crane, M

    2003-03-17

    The toxicity of the anti-fouling biocides tributyltin (TBTO), copper, and Irgarol 1051 (irgarol) at nominal concentrations ranging from 10 to 10,000 microg l(-1) was investigated against the speed of encystment and successful formation of a protective cyst of the cercariae of Parorchis acanthus. For all biocide exposures, cercariae had a much slower rate of encystment and reduced cyst formation than controls. Exposure of the snail host Nucella lapillus for 7 d caused complete cessation of cercarial shedding in irgarol-exposed snails but had no effect on cercarial encystment from TBTO and copper-exposed snails. The mechanisms of toxicity of the biocides are briefly discussed.

  9. Effects of surface-active block copolymers with oxyethylene and fluoroalkyl side chains on the antifouling performance of silicone-based films.

    PubMed

    Martinelli, Elisa; Gunes, Deniz; Wenning, Brandon M; Ober, Christopher K; Finlay, John A; Callow, Maureen E; Callow, James A; Di Fino, Alessio; Clare, Anthony S; Galli, Giancarlo

    2016-01-01

    Block copolymers made from a poly(dimethyl siloxane) (Si) and a poly(meth)acrylate carrying oxyethylene (EG) or fluoroalkyl (AF) side chains were synthesized and incorporated as surface-active components into a silicone matrix to produce cross-linked films with different surface hydrophilicity/phobicity. Near-edge X-ray absorption fine structure (NEXAFS) studies showed that film surfaces containing Si-EG were largely populated by the siloxane, with the oxyethylene chains present only to a minor extent. In contrast, the fluorinated block was selectively segregated to the polymer-air interface in films containing Si-AF as probed by NEXAFS and X-ray photoelectron spectroscopy (XPS) analyses. Such differences in surface composition were reflected in the biological performance of the coatings. While the films with Si-EG showed a higher removal of both Ulva linza sporelings and Balanus amphitrite juveniles than the silicone control, those with Si-AF exhibited excellent antifouling properties, preventing the settlement of cyprids of B. amphitrite.

  10. Fabrication and anti-fouling properties of photochemically and thermally immobilized poly(ethylene oxide) and low molecular weight poly(ethylene glycol) thin films.

    PubMed

    Wang, Hui; Ren, Jin; Hlaing, Aye; Yan, Mingdi

    2011-02-01

    Poly(ethylene oxide) (PEO) and low molecular weight poly(ethylene glycol) (PEG) were covalently immobilized on silicon wafers and gold films by way of the CH insertion reaction of perfluorophenyl azides (PFPAs) by either photolysis or thermolysis. The immobilization does not require chemical derivatization of PEO or PEG, and polymers of different molecular weights were successfully attached to the substrate to give uniform films. Microarrays were also generated by printing polymer solutions on PFPA-functionalized wafer or Au slides followed by light activation. For low molecular weight PEG, the immobilization was highly dependent on the quality of the film deposited on the substrate. While the spin-coated and printed PEG showed poor immobilization efficiency, thermal treatment of the PEG melt on PFPA-functionalized surfaces resulted in excellent film quality, giving, for example, a grafting density of 9.2×10(-4)Å(-2) and an average distance between grafted chains of 33Å for PEG 20,000. The anti-fouling property of the films was evaluated by fluorescence microscopy and surface plasmon resonance imaging (SPRi). Low protein adsorption was observed on thermally-immobilized PEG whereas the photoimmobilized PEG showed increased protein adsorption. In addition, protein arrays were created using polystyrene (PS) and PEG based on the differential protein adsorption of the two polymers.

  11. Surface grafting of blood compatible zwitterionic poly(ethylene glycol) on diamond-like carbon-coated stent.

    PubMed

    Lee, Bong Soo; Shin, Hong-Sub; Park, Kwideok; Han, Dong Keun

    2011-03-01

    Blood compatibility is the most important aspect for blood-contacting medical devices including cardiovascular stents. In this study, the surface of nickel-titanium (TiNi) stent was coated with diamond-like carbon (DLC) and then subsequently grafted by using zwitterion (N(+) and SO(3) (-))-linked poly(ethylene glycol) (PEG). We hypothesize that this coupling of zwitterion and PEG may significantly improve blood compatibility of DLC-coated TiNi stent. The surface modified TiNi stents, including PEG-grafted stent (DLC-PEG) and zwitterionic PEG-grafted one (DLC-PEG-N-S) were the main focus on the tests of surface characteristics and blood compatibility. The zwitterionic PEG derivatives were obtained from a series of chemical reactions at room temperature. The results exhibited that as compared to the DLC-PEG, the hydrophilicity was much better with DLC-PEG-N-S and significantly increased atomic percentage of oxygen and nitrogen proved the entity of zwitterions on the surface of DLC-PEG-N-S. Meanwhile, the adsorption of blood proteins such as, human serum albumin (HSA) and fibrinogen was found considerably down-regulated in DLC-PEG-N-S, due mainly to the protein-repellent effect of PEG and zwitterion. Microscopic observation also revealed that as compared with the other substrates without zwitterion, the degree of platelet adhesion was the lowest with DLC-PEG-N-S. In addition, DLC-PEG-N-S retained an extended blood coagulation time as measured by activated partial thromboplastin time (APTT). The present results suggested that surface grafting of zwitterionic PEG derivatives could substantially enhance the blood compatibility of TiNi-DLC stent. In conclusion, anti-fouling properties of PEG and zwitterions are expected to be very useful in advancing overall stent performance.

  12. Thermochemistry of CaO-MgO-Al2O3-SiO2 (CMAS) and Advanced Thermal and Environmental Barrier Coating Systems

    NASA Technical Reports Server (NTRS)

    Costa, Gustavo C. C.; Zhu, Dongming

    2016-01-01

    CaO-MgO-Al2O3-SiO2 (CMAS) oxides are constituents in a broad number of materials and minerals which have recently inferred to discussions in materials science, planetary science, geochemistry and cosmochemistry communities. In materials science, there is increasing interest in the degradation studies of thermal (TBC) and environmental (EBC) barrier coatings of gas turbines by molten CMAS. These coatings have been explored to be applied on silicon-based ceramics and composites which are lighter and more temperature capable hot-section materials of gas turbines than the current Ni-based superalloys. The degradation of the coatings occurs when CMAS minerals carried by the intake air into gas turbines, e.g. in aircraft engines, reacts at high temperatures (1000C) with the coating materials. This causes premature failure of the static and rotating components of the turbine engines. We discuss some preliminary results of the reactions between CMAS and Rare-Earth (RE Y, Yb and Gd) oxide stabilized ZrO2 systems, and stability of the resulting oxides and silicates.

  13. Vacuum Plasma Sprayed Metallic Coatings

    NASA Astrophysics Data System (ADS)

    Shankar, S.; Koenig, D. E.; Dardi, L. E.

    1981-10-01

    Recognizing the fundamental cost advantage, technical capabilities, and compositional flexibility of reduced pressure (vacuum) plasma spraying compared to other overlay coating methods, an advanced, second generation, closed chamber deposition process called VPX (a Howmet trademark) was developed. An automated experimental facility for coating gas turbine engine components was also constructed. This paper describes several important features of the process and equipment. It shows that the use of optimized spray parameters combined with an appropriate schedule of relative orientations between the gun and work-piece can be used to produce dense and highly reproducible coatings of either uniform or controlled thickness distributions. The chemical composition, microstructure, and interfacial characteristics of typical MCrAlY coatings are reported. Some effects of operating procedures and MCrAlY chemical composition on coating density are noted. The results of mechanical property and burner rig tests of coated material are also described.

  14. Cermet composite thermal spray coatings for erosion and corrosion protection in combustion environments of advanced coal-fired boilers. Semi-annual technical progress report, February 1996--July 1996

    SciTech Connect

    Banovic, S.W.; Levin, B.F.; DuPont, J.N.; Marder, A.R.

    1996-08-01

    Present coal-fired boiler environments remain hostile to the materials of choice since corrosion and erosion can be a serious problem in certain regions of the boiler. Recently, the Clean Air Act Amendment is requiring electric power plants to reduce NO{sub x}, emissions to the environment. To reduce NO{sub x}, emissions, new low NO{sub x}, combustors are utilized which burn fuel with a substoichiometric amount of oxygen (i.e., low oxygen partial pressure). In these low NO{sub x} environments, H{sub 2}S gas is a major source of sulfur. Due to the sulfidation process, corrosion rates in reducing parts of boilers have increased significantly and existing boiler tube materials do not always provide adequate corrosion resistance. Combined attack due to corrosion and erosion is a concern because of the significantly increased operating costs which result in material failures. One method to combat corrosion and erosion in coal-fired boilers is to apply coatings to the components subjected to aggressive environments. Thermal spray coatings, a cermet composite comprised of hard ceramic phases of oxide and/or carbide in a metal binder, have been used with some success as a solution to the corrosion and erosion problems in boilers. However, little is known on the effect of the volume fraction, size, and shape of the hard ceramic phase on the erosion and corrosion resistance of the thermally sprayed coatings. It is the objective of this research to investigate metal matrix composite (cermet) coatings in order to determine the optimum ceramic/metal combination that will give the best erosion and corrosion resistance in new advanced coal-fired boilers.

  15. Thermal Barrier Coating Workshop

    NASA Technical Reports Server (NTRS)

    Brindley, W. J. (Compiler); Lee, W. Y. (Compiler); Goedjen, J. G. (Compiler); Dapkunas, S. J. (Compiler)

    1995-01-01

    This document contains the agenda and presentation abstracts for the Thermal Barrier Coating Workshop, sponsored by NASA, DOE, and NIST. The workshop covered thermal barrier coating (TBC) issues related to applications, processing, properties, and modeling. The intent of the workshop was to highlight the state of knowledge on TBC's and to identify critical gaps in knowledge that may hinder TBC use in advanced applications. The workshop goals were achieved through presentations by 22 speakers representing industry, academia, and government as well as through extensive discussion periods.

  16. Low Temperature Powder Coating

    DTIC Science & Technology

    2011-02-09

    Patterson AFB, OH David Piatkowski, Chris Mahendra NAVAIR James Davila, Chris Geib SAIC Beavercreek, OH O G D E N A I R L O G I S T I C S C E N T...PUBLICATIONS Geib , C.W., Davila J.A., Patterson W., et al. “Low Temperature Cure Powder Coating, ESTCP Project WP-0614.” Joint Services Environmental...Management Conference, Columbus, Ohio. 21 – 24 May 2007. Geib , C.W., Davila J.A., Patterson W., et al. “Advances and Testing of Powder Coatings for Aerospace

  17. Anti-HER2 antibody and ScFvEGFR-conjugated antifouling magnetic iron oxide nanoparticles for targeting and magnetic resonance imaging of breast cancer.

    PubMed

    Chen, Hongwei; Wang, Liya; Yu, Qiqi; Qian, Weiping; Tiwari, Diana; Yi, Hong; Wang, Andrew Y; Huang, Jing; Yang, Lily; Mao, Hui

    2013-01-01

    Antifouling magnetic iron oxide nanoparticles (IONPs) coated with block copolymer poly(ethylene oxide)-block-poly(γ-methacryloxypropyltrimethoxysilane) (PEO-b-PγMPS) were investigated for improving cell targeting by reducing nonspecific uptake. Conjugation of a HER2 antibody, Herceptin®, or a single chain fragment (ScFv) of antibody against epidermal growth factor receptor (ScFvEGFR) to PEO-b-PγMPS-coated IONPs resulted in HER2-targeted or EGFR-targeted IONPs (anti-HER2-IONPs or ScFvEGFR-IONPs). The anti-HER2-IONPs bound specifically to SK-BR-3, a HER2-overexpressing breast cancer cell line, but not to MDA-MB-231, a HER2-underexpressing cell line. On the other hand, the ScFvEGFR-IONPs showed strong reactivity with MDA-MB-231, an EGFR-positive human breast cancer cell line, but not with MDA-MB-453, an EGFR-negative human breast cancer cell line. Transmission electron microscopy revealed internalization of the receptor-targeted nanoparticles by the targeted cancer cells. In addition, both antibody-conjugated and non-antibody-conjugated IONPs showed reduced nonspecific uptake by RAW264.7 mouse macrophages in vitro. The developed IONPs showed a long blood circulation time (serum half-life 11.6 hours) in mice and low accumulation in both the liver and spleen. At 24 hours after systemic administration of ScFvEGFR-IONPs into mice bearing EGFR-positive breast cancer 4T1 mouse mammary tumors, magnetic resonance imaging revealed signal reduction in the tumor as a result of the accumulation of the targeted IONPs.

  18. Toxic effects of several types of antifouling paints in human and rat hepatic or epidermal cells.

    PubMed

    de Sousa, G; Delescluse, C; Pralavorio, M; Perichaud, M; Avon, M; Lafaurie, M; Rahmani, R

    1998-08-01

    Fouling is the successive development of marine organisms on immersed surfaces, a process which has heavy negative economic impacts. Several antifouling technologies, generally based on the leaching of biocides from painted surfaces, have been developed, but these biocides are toxic to the environment. Hence, we compared the toxicity of several currently used paint lixiviats in rat hepatocytes, human HepG2 and HaCaT cells. Acute toxicity was assessed by the Neutral Red and MTT assays. Chronic effect was tested using induction of the 7-ethoxyresorufin-O-deethylase (EROD) activity as a marker. Large variations were observed among the various cell types or the antifouling formulations, both in terms of IC50 values (from approximately 0.5 to approximately 10%, v/v) and EROD induction (from approximately 1 to 10-fold over control). These differences appear to be related to variable biocide (copper compounds, organotins, etc...) concentrations in the different paint formulations, or to the specific metabolic capabilities of the cell system used.

  19. Antifouling Thin-Film Composite Membranes by Controlled Architecture of Zwitterionic Polymer Brush Layer.

    PubMed

    Liu, Caihong; Lee, Jongho; Ma, Jun; Elimelech, Menachem

    2017-02-21

    In this study, we demonstrate a highly antifouling thin-film composite (TFC) membrane by grafting a zwitterionic polymer brush via atom-transfer radical-polymerization (ATRP), a controlled, environmentally benign chemical process. Initiator molecules for polymerization were immobilized on the membrane surface by bioinspired catechol chemistry, leading to the grafting of a dense zwitterionic polymer brush layer. Surface characterization revealed that the modified membrane exhibits reduced surface roughness, enhanced hydrophilicity, and lower surface charge. Chemical force microscopy demonstrated that the modified membrane displayed foulant-membrane interaction forces that were 1 order of magnitude smaller than those of the pristine TFC membrane. The excellent fouling resistance imparted by the zwitterionic brush layer was further demonstrated by significantly reduced adsorption of proteins and bacteria. In addition, forward osmosis fouling experiments with a feed solution containing a mixture of organic foulants (bovine-serum albumin, alginate, and natural organic matter) indicated that the modified membrane exhibited significantly lower water flux decline compared to the pristine TFC membrane. The controlled architecture of the zwitterionic polymer brush via ATRP has the potential for a facile antifouling modification of a wide range of water treatment membranes without compromising intrinsic transport properties.

  20. Novel antifouling surface with improved hemocompatibility by immobilization of polyzwitterions onto silicon via click chemistry

    NASA Astrophysics Data System (ADS)

    Zheng, Sunxiang; Yang, Qian; Mi, Baoxia

    2016-02-01

    A novel procedure is presented to develop an antifouling silicon surface with improved hemocompatibility by using a zwitterionic polymer, poly(sulfobetaine methacrylate) (polySBMA). Functionalization of the silicon surface with polySBMA involved the following three steps: (1) an alkyne terminated polySBMA was synthesized by RAFT polymerization; (2) a self-assembled monolayer with bromine end groups was constructed on the silicon surface, and then the bromine end groups were replaced by azide groups; and (3) the polySBMA was attached to the silicon surface by azide-alkyne cycloaddition click reaction. Membrane characterization confirmed a successful silicon surface modification with almost 100% coverage by polySBMA and an extremely hydrophilic surface after such modification. The polySBMA-modified silicon surface was found to have excellent anti-nonspecific adsorption properties for both bovine serum albumin (BSA) protein and model bacterial cells. Whole blood adsorption experiments showed that the polySBMA-modified silicon surface exhibited excellent hemocompatibility and effective anti-adhesion to blood cells. Silicon membranes with such antifouling and hemocompatible surfaces can be advantageously used to drastically extend the service life of implantable medical devices such as artificial kidney devices.

  1. Toward Cell Selective Surfaces: Cell Adhesion and Proliferation on Breath Figures with Antifouling Surface Chemistry.

    PubMed

    Martínez-Campos, Enrique; Elzein, Tamara; Bejjani, Alice; García-Granda, Maria Jesús; Santos-Coquillat, Ana; Ramos, Viviana; Muñoz-Bonilla, Alexandra; Rodríguez-Hernández, Juan

    2016-03-01

    We report the preparation of microporous functional polymer surfaces that have been proven to be selective surfaces toward eukaryotic cells while maintaining antifouling properties against bacteria. The fabrication of functional porous films has been carried out by the breath figures approach that allowed us to create porous interfaces with either poly(ethylene glycol) methyl ether methacrylate (PEGMA) or 2,3,4,5,6-pentafluorostyrene (5FS). For this purpose, blends of block copolymers in a polystyrene homopolymer matrix have been employed. In contrast to the case of single functional polymer, using blends enables us to vary the chemical distribution of the functional groups inside and outside the formed pores. In particular, fluorinated groups were positioned at the edges while the hydrophilic PEGMA groups were selectively located inside the pores, as demonstrated by TOF-SIMS. More interestingly, studies of cell adhesion, growth, and proliferation on these surfaces confirmed that PEGMA functionalized interfaces are excellent candidates to selectively allow cell growth and proliferation while maintaining antifouling properties.

  2. Improved Plate Assay for Antifouling Substances Using Blue Mussel Mytilus edulis galloprovincialis.

    PubMed

    Sera; Iida; Adachi; Shizuri

    2000-07-01

    An improved plate assay for screening antifoulants against blue mussels, Mytilus edulis galloprovincialis, was designed based on an assay contrived by Ina and colleagues. To obtain more reliable results, the number of test mussels for one sample was increased from 4 to 10. Cardboard pieces used as test plates were cut into rectangular shapes to separate the test sample and the blank zone, which are of the same area. Activity was expressed numerically. In this improved method, several inhibitors of byssus thread formation were isolated by using a smaller amount of sample per area than in the original method. Previously our laboratory developed a foot-stimulating bioassay for the same purpose. This method requires only a small amount of sample and is therefore useful for isolating antifouling substances from natural sources, including marine organisms. However, the inhibition of byssus thread formation cannot be directly evaluated in the foot-stimulating method. The improved plate assay and the foot-stimulating method were examined and compared using a secosterol from the sponge Dysidea granulosa and CuSO(4).

  3. Immunotoxicity in ascidians: antifouling compounds alternative to organotins-IV. The case of zinc pyrithione.

    PubMed

    Cima, Francesca; Ballarin, Loriano

    2015-03-01

    New biocides such as the organometallic compound zinc pyrithione (ZnP) have been massively introduced by many countries in formulations of antifouling paints following the ban on tributyltin (TBT). The effects of sublethal concentrations (LC50=82.5 μM, i.e., 26.2 mg/l) on cultured haemocytes of the ascidian Botryllus schlosseri have been investigated and compared with TBT. The percentage of haemocytes with amoeboid morphology and containing phagocytised yeast cells were significantly (p<0.05) reduced after exposure to 0.1 (31.7 μg/l) and 0.5 μM (158 μg/l), respectively. An antagonistic interaction in inducing cytoskeletal alterations was observed when ZnP and TBT were co-present in the exposure medium. ZnP affected only the actin component. As caused by TBT, ZnP induced apoptosis and inhibited both oxidative phosphorylation and lysosomal activities. In contrast to the case of TBT, a decrement in Ca(2+)-ATPase activity and a decrease in cytosolic Ca(2+) were detected after incubation at the highest concentration (1 μM, i.e., 317.7 μg/l) used. In comparison with other antifouling compounds, ZnP shows as much toxicity as TBT to cultured haemocytes at extremely low concentrations interfering with fundamental cell activities.

  4. Preparation Method of Crack-free PVDF Microfiltration Membrane with Enhanced Antifouling Characteristics.

    PubMed

    Woo, Sahng Hyuck; Lee, Ju Sung; Lee, Hyun Ho; Park, Jinwon; Min, Byoung Ryul

    2015-08-05

    This study proposes a method to prepare a crack-free poly(vinylidene fluoride) (PVDF) microfiltration (MF) membrane with enhanced antifouling property. In the study, blending 4% poly(vinylidene fluoride)-graft-poly(sulfopropyl methacrylate) (PVDF-g-PSPMA) and 1.5% potassium perchlorate (KClO4) led to crack prevention during membrane preparation via nonsolvent induced phase separation (NIPS) when compared with blending with 4% PVDF-g-PSPMA only (without KClO4). The resulting crack-free membrane (A3) had both smooth surface structure and hydrophilicity in comparison with pristine PVDF membrane (A1). In addition, blending with PVDF-g-PSPMA and KClO4 also allowed the A3 membrane to exhibit uniform pore size distribution (PSD) and smooth surface structure, compared with PVDF membrane commercially available from company "M" in Germany. The aforementioned properties led to antifouling characteristics in the crack-free membrane (A3). According to flux performances, flux recovery and cumulative permeate volume (between 120 and 240 min) of crack-free membrane (A3) were 11.41 and 17.41% superior to those of commercial membrane, respectively.

  5. Improved antifouling properties of polyamide nanofiltration membranes by reducing the density of surface carboxyl groups.

    PubMed

    Mo, Yinghui; Tiraferri, Alberto; Yip, Ngai Yin; Adout, Atar; Huang, Xia; Elimelech, Menachem

    2012-12-18

    Carboxyls are inherent functional groups of thin-film composite polyamide nanofiltration (NF) membranes, which may play a role in membrane performance and fouling. Their surface presence is attributed to incomplete reaction of acyl chloride monomers during the membrane active layer synthesis by interfacial polymerization. In order to unravel the effect of carboxyl group density on organic fouling, NF membranes were fabricated by reacting piperazine (PIP) with either isophthaloyl chloride (IPC) or the more commonly used trimesoyl chloride (TMC). Fouling experiments were conducted with alginate as a model hydrophilic organic foulant in a solution, simulating the composition of municipal secondary effluent. Improved antifouling properties were observed for the IPC membrane, which exhibited lower flux decline (40%) and significantly greater fouling reversibility or cleaning efficiency (74%) than the TMC membrane (51% flux decline and 40% cleaning efficiency). Surface characterization revealed that there was a substantial difference in the density of surface carboxyl groups between the IPC and TMC membranes, while other surface properties were comparable. The role of carboxyl groups was elucidated by measurements of foulant-surface intermolecular forces by atomic force microscopy, which showed lower adhesion forces and rupture distances for the IPC membrane compared to TMC membranes in the presence of calcium ions in solution. Our results demonstrated that a decrease in surface carboxyl group density of polyamide membranes fabricated with IPC monomers can prevent calcium bridging with alginate and, thus, improve membrane antifouling properties.

  6. Species-specific engineered antifouling topographies: correlations between the settlement of algal zoospores and barnacle cyprids.

    PubMed

    Schumacher, James F; Aldred, Nick; Callow, Maureen E; Finlay, John A; Callow, James A; Clare, Anthony S; Brennan, Anthony B

    2007-01-01

    Novel, non-toxic antifouling technologies are focused on the manipulation of surface topography to deter settlement of the dispersal stages of fouling organisms. This study investigated the effect of the aspect ratio (feature height/feature width) of topographical features engineered in polydimethylsiloxane, on the settlement of cyprids of Balanus amphitrite and zoospores of Ulva linza. The correlation of relative aspect ratios to antifouling efficacy was proven to be significant. An increase in aspect ratio resulted in an increase of fouling deterrence for both zoospores and cyprids. The spore density of Ulva was reduced 42% with each unit increase in aspect ratio of the Ulva-specific Sharklet AF topography. Similarly, the number of settled cyprids was reduced 45% with each unit increase in aspect ratio. The newly described barnacle-specific Sharklet AF topography (40 microm feature height, aspect ratio of 2) reduced cyprid settled by 97%. Techniques have been developed to superimpose the smaller Ulva-specific topographies onto the barnacle-specific surfaces into a hierarchical structure to repel both organisms simultaneously. The results for spore settlement on first-generation hierarchical surfaces provide insight for the efficacious design of such structures when targeting multiple settling species.

  7. Zwitterionic modification of polyurethane membranes for enhancing the anti-fouling property.

    PubMed

    Liu, Peiming; Huang, Tao; Liu, Pingsheng; Shi, Shufeng; Chen, Qiang; Li, Li; Shen, Jian

    2016-10-15

    Polyurethane (PU) is a biopolymer that has been commonly used for biomedical applications. However, the biofouling phenomenon on the hydrophobic PU surface is one of the crucial issues that embarrassing its applications. Here, we report a facile & efficient approach to improve the anti-biofouling ability of the PU substrates. Active residues were firstly generated on the PU surface by using the low temperature air-plasma treatment, promoting the immobilization of the atom transfer radical polymerization (ATRP) initiators on the surface. Then, three types of zwitterionic polymer brushes, as well as PEG brushes, have been fabricated on the PU substrates through surface-initiated ATRP (SI-ATRP). Robust surface characterizations that capable of revealing the surface chemistry (including X-ray photoelectron spectroscopy (XPS) and wettability tests), and antifouling evaluations of the PU substrates (protein adsorption, platelet adhesion, and cell adhesion measurements) were performed. Results showed that three types of zwitterionic brushes have been successful grafted on the PU surface, respectively. And the three types of zwitterionic brushes, in general, significantly inhibited the protein adsorption, the platelet adhesion, and the cell adhesion on the PU surface, endowing a significantly improved anti-fouling ability to the PU substrates. Furthermore, we found that this facial zwitterionic surface modification did not compromise the mechanical property of the PU substrates. This strategy could be easily exploited to PU-based biomaterials to improve their performance in many applications.

  8. Anti-fouling properties of Fab' fragments immobilized on silane-based adlayers

    NASA Astrophysics Data System (ADS)

    Crivianu-Gaita, Victor; Romaschin, Alexander; Thompson, Michael

    2015-12-01

    Biosensors require surfaces that are highly specific towards the target analyte and that are minimally fouling. However, surface tuning to minimize fouling is a difficult task. The last decade has seen an increase in the use of immobilized antigen-binding antibody fragments (Fab') in biosensors. One Fab' linker compound S-(11-trichlorosilyl-undecanyl)-benzothiosulfonate (TUBTS) and three spacers were used to create the silane-based adlayers. The ultra-high frequency electromagnetic piezoelectric acoustic sensor (EMPAS) was used to gauge the fouling properties of the various surfaces using bovine serum albumin (BSA), goat IgG, and mouse serum. X-ray photoelectron spectroscopy (XPS), contact angle, and atomic force microscopy (AFM) were employed to characterize the surfaces. It was discovered that immobilized oriented Fab' fragments reduced the fouling levels of surfaces up to 80% compared to the surfaces without fragments. An explanation for this phenomenon is that the antibody fragments increase the hydration of the surfaces and aid in the formation of an anti-fouling water barrier. The anti-fouling effect of the Fab' fragments is at its maximum when there is an even distribution of fragments across the surfaces. Finally, using Fab'-covered surfaces, a cancer biomarker was detected from serum, showing the applicability of this work to the field of biodetection.

  9. Exploration of zwitterionic cellulose acetate antifouling ultrafiltration membrane for bovine serum albumin (BSA) separation.

    PubMed

    Liu, Yang; Huang, Haitao; Huo, Pengfei; Gu, Jiyou

    2017-06-01

    This study focused on the preparation of a new kind of membrane material, zwitterionic cellulose acetate (ZCA), via a three-step procedure consist of oxidization, Schiff base and quaternary amination reaction, and the fabrication of antifouling ZCA ultrafiltration membrane by the non-solvent-induced phase separation method (NIPS). The morphologies, surface chemical structures and compositions of the obtained CA and ZCA membranes were thoroughly characterized by field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray (EDX) spectroscopy, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. Meanwhile, the thermal stability, porosity and average pore size of two investigated membranes were also studied. As a result, the ZCA membrane displayed significantly improved hydrophilicity and water permeability compared with those of the reference CA membrane, despite a slight decrease in the protein rejection ratio. According to the cycle ultrafiltration performance of bovine serum albumin (BSA) solution and protein adsorption experiment, ZCA membrane exhibited better flux recovery property and fouling resistant ability, especially irreversible fouling resistant ability, suggesting superior antifouling performance. This new approach gives polymer-based membrane a long time life and excellent ultrafiltration performance, and seems promising for potential applications in the protein separation.

  10. Improved antifouling properties of PVDF membranes modified with oppositely charged copolymer.

    PubMed

    Shen, Xiang; Zhao, Yiping; Feng, Xia; Bi, Sixin; Ding, Wenbin; Chen, Li

    2013-01-01

    Biofouling resulting from the attachment of microorganisms communities to the membrane surface is the major obstacle for the widespread application of membrane technology. This work develops a feasible approach to prepare an anti-biofouling poly(vinylidene fluoride) (PVDF) membrane. A copolymer that possessed oppositely charged groups was first synthesized via radical copolymerization with methyl methacrylate, 2-methacryloxy ethyltrimethyl ammonium chloride and 2-acrylamide-2-methyl propane sulphonic acid as monomers. The copolymer was blended with the PVDF powder to prepare the antifouling membrane via the immersed phase inversion method. The antifouling properties of the modified PVDF membrane were studied by X-ray photoelectron spectroscopy, field emission scanning electron microscopy, water contact angle measurement, zeta-potential measurement, protein adsorption, microbial adhesion and filtration experiments. The modified PVDF membrane showed limited adsorption and adhesion of protein bovine serum albumin and microbes (Escherichia coli and Saccharomyces cerevisiae) with increasing copolymer concentration in the casting solution. The modified PVDF membrane exhibited excellent antibiofouling properties.

  11. Preparation of hydrophilic and antifouling polysulfone ultrafiltration membrane derived from phenolphthalin by copolymerization method

    NASA Astrophysics Data System (ADS)

    Liu, Zhixiao; Mi, Zhiming; Chen, Chunhai; Zhou, Hongwei; Zhao, Xiaogang; Wang, Daming

    2017-04-01

    In this task, carboxylated polysulfone (PSF-COOH) was achieved by introducing the monomer of phenolphthalin (PPL) containing carboxyl to the molecule backbone of polysulfone (PSF). And a series of PSF-COOH copolymers with different carboxylation degree was synthesized by adjusting the molar (%) of bisphenol A (BPA) and PPL in direct copolymerization method and was prepared as PSF-COOH ultrafiltration membranes via phase separation method. The effect of PPL molar (%) in copolymers on the morphology, hydrophilicity, permeation flux, antifouling and mechanical properties of membranes was investigated by scanning electron microscope (SEM), atomic force microscope (AFM), water contact angle, ultrafiltration experiments and universal testing machine, respectively. The results showed that with the increased carboxyl content in membranes, the hydrophilicity, permeation fluxes and antifouling properties of membranes gradually increased. When the molar (%) of PPL to BPA was 100:0, the membrane exhibited the highest pure water flux (329.6 L/m2 h) and the maximum flux recovery rate (92.5%). When the content of carboxyl in the membrane was 80% or more, after three cycles of BSA solution (1 g/L) filtration, the flux recovery rate was basically constant or showed a slightly increase. Thus, it can achieve the goal of long term usage without compromising flux.

  12. From Broad-Spectrum Biocides to Quorum Sensing Disruptors and Mussel Repellents: Antifouling Profile of Alkyl Triphenylphosphonium Salts

    PubMed Central

    Martín-Rodríguez, Alberto J.; Babarro, Jose M. F.; Lahoz, Fernando; Sansón, Marta; Martín, Víctor S.; Norte, Manuel; Fernández, José J.

    2015-01-01

    ‘Onium’ compounds, including ammonium and phosphonium salts, have been employed as antiseptics and disinfectants. These cationic biocides have been incorporated into multiple materials, principally to avoid bacterial attachment. In this work, we selected 20 alkyl-triphenylphosphonium salts, differing mainly in the length and functionalization of their alkyl chains, in fulfilment of two main objectives: 1) to provide a comprehensive evaluation of the antifouling profile of these molecules with relevant marine fouling organisms; and 2) to shed new light on their potential applications, beyond their classic use as broad-spectrum biocides. In this regard, we demonstrate for the first time that these compounds are also able to act as non-toxic quorum sensing disruptors in two different bacterial models (Chromobacterium violaceum and Vibrio harveyi) as well as repellents in the mussel Mytilus galloprovincialis. In addition, their inhibitory activity on a fouling-relevant enzymatic model (tyrosinase) is characterized. An analysis of the structure-activity relationships of these compounds for antifouling purposes is provided, which may result useful in the design of targeted antifouling solutions with these molecules. Altogether, the findings reported herein provide a different perspective on the biological activities of phosphonium compounds that is particularly focused on, but, as the reader will realize, is not limited to their use as antifouling agents. PMID:25897858

  13. From broad-spectrum biocides to quorum sensing disruptors and mussel repellents: antifouling profile of alkyl triphenylphosphonium salts.

    PubMed

    Martín-Rodríguez, Alberto J; Babarro, Jose M F; Lahoz, Fernando; Sansón, Marta; Martín, Víctor S; Norte, Manuel; Fernández, José J

    2015-01-01

    'Onium' compounds, including ammonium and phosphonium salts, have been employed as antiseptics and disinfectants. These cationic biocides have been incorporated into multiple materials, principally to avoid bacterial attachment. In this work, we selected 20 alkyl-triphenylphosphonium salts, differing mainly in the length and functionalization of their alkyl chains, in fulfilment of two main objectives: 1) to provide a comprehensive evaluation of the antifouling profile of these molecules with relevant marine fouling organisms; and 2) to shed new light on their potential applications, beyond their classic use as broad-spectrum biocides. In this regard, we demonstrate for the first time that these compounds are also able to act as non-toxic quorum sensing disruptors in two different bacterial models (Chromobacterium violaceum and Vibrio harveyi) as well as repellents in the mussel Mytilus galloprovincialis. In addition, their inhibitory activity on a fouling-relevant enzymatic model (tyrosinase) is characterized. An analysis of the structure-activity relationships of these compounds for antifouling purposes is provided, which may result useful in the design of targeted antifouling solutions with these molecules. Altogether, the findings reported herein provide a different perspective on the biological activities of phosphonium compounds that is particularly focused on, but, as the reader will realize, is not limited to their use as antifouling agents.

  14. Microtopography of the eye surface of the crab Carcinus maenas: an atomic force microscope study suggesting a possible antifouling potential

    PubMed Central

    Greco, G.; Lanero, T. Svaldo; Torrassa, S.; Young, R.; Vassalli, M.; Cavaliere, A.; Rolandi, R.; Pelucchi, E.; Faimali, M.; Davenport, J.

    2013-01-01

    Marine biofouling causes problems for technologies based on the sea, including ships, power plants and marine sensors. Several antifouling techniques have been applied to marine sensors, but most of these methodologies are environmentally unfriendly or ineffective. Bioinspiration, seeking guidance from natural solutions, is a promising approach to antifouling. Here, the eye of the green crab Carcinus maenas was regarded as a marine sensor model and its surface characterized by means of atomic force microscopy. Engineered surface micro- and nanotopography is a new mechanism found to limit biofouling, promising an effective solution with much reduced environmental impact. Besides giving a new insight into the morphology of C. maenas eye and its characterization, our study indicates that the eye surface probably has antifouling/fouling-release potential. Furthermore, the topographical features of the surface may influence the wettability properties of the structure and its interaction with organic molecules. Results indicate that the eye surface micro- and nanotopography may lead to bioinspired solutions to antifouling protection. PMID:23635491

  15. Concentration of antifouling biocides and metals in sediment core samples in the northern part of Hiroshima Bay.

    PubMed

    Tsunemasa, Noritaka; Yamazaki, Hideo

    2014-06-04

    Accumulation of Ot alternative antifoulants in sediment is the focus of this research. Much research had been done on surface sediment, but in this report, the accumulation in the sediment core was studied. The Ot alternative antifoulants, Diuron, Sea-Nine211, and Irgarol 1051, and the latter's degradation product, M1, were investigated in five samples from the northern part of Hiroshima Bay. Ot compounds (tributyltin (TBT) and triphenyltin (TPT)) were also investigated for comparison. In addition, metal (Pb, Cu, Zn, Fe and Mn) levels and chronology were measured to better understand what happens after accumulation on the sea floor. It was discovered that Ot alternative antifoulant accumulation characteristics in sediment were like Ot compounds, with the concentration in the sediment core being much higher than surface sediment. The concentration in sediment seems to have been affected by the regulation of Ot compounds in 1990, due to the concentration of Ot alternative antifoulants and Ot compounds at the survey point in front of the dock, showing an increase from almost the same layer after the regulation.

  16. Concentration of Antifouling Biocides and Metals in Sediment Core Samples in the Northern Part of Hiroshima Bay

    PubMed Central

    Tsunemasa, Noritaka; Yamazaki, Hideo

    2014-01-01

    Accumulation of Ot alternative antifoulants in sediment is the focus of this research. Much research had been done on surface sediment, but in this report, the accumulation in the sediment core was studied. The Ot alternative antifoulants, Diuron, Sea-Nine211, and Irgarol 1051, and the latter’s degradation product, M1, were investigated in five samples from the northern part of Hiroshima Bay. Ot compounds (tributyltin (TBT) and triphenyltin (TPT)) were also investigated for comparison. In addition, metal (Pb, Cu, Zn, Fe and Mn) levels and chronology were measured to better understand what happens after accumulation on the sea floor. It was discovered that Ot alternative antifoulant accumulation characteristics in sediment were like Ot compounds, with the concentration in the sediment core being much higher than surface sediment. The concentration in sediment seems to have been affected by the regulation of Ot compounds in 1990, due to the concentration of Ot alternative antifoulants and Ot compounds at the survey point in front of the dock, showing an increase from almost the same layer after the regulation. PMID:24901529

  17. The legal design of the international and European Union ban on tributyltin antifouling paint: direct and indirect effects.

    PubMed

    Gipperth, Lena

    2009-02-01

    The Convention on the Control of Harmful Anti-fouling Systems on Ships (AFS Convention), which was adopted in 2001 and will come into force in September 2008, bans the use of TBT (tributyltin) antifouling paint on ships. The EU (European Union) effectively implemented the Convention on 1 January 2008 by enforcing a similar ban. Several states have national restrictions and bans in place. The regulation on TBT antifouling paint aims at checking the risk of adverse effects on marine ecosystems. The legal and political situation is, however, characterized by complex relations between different layers of legislation, the use of several different legal techniques, and levels of ambition. The international and EU bans thereby cause some indirect effects, which are only partly included in what is seen as 'the TBT issue' and so only partly assessed in the legal process of the ban. This article discusses the expediency of the existing legislation and legal strategies aimed at reducing the negative environmental effects of TBT-like toxins in marine ecosystems and indirect effects of such actions. It considers the adequacy and limits of current regulatory approaches for handling complex environmental problems, such as TBT in antifouling paint.

  18. Polyacrylonitrile block copolymers for the preparation of a thin carbon coating around TiO2 nanorods for advanced lithium-ion batteries.

    PubMed

    Oschmann, Bernd; Bresser, Dominic; Tahir, Muhammad Nawaz; Fischer, Karl; Tremel, Wolfgang; Passerini, Stefano; Zentel, Rudolf

    2013-11-01

    Herein, a new method for the realization of a thin and homogenous carbonaceous particle coating, made by carbonizing RAFT polymerization derived block copolymers anchored on anatase TiO2 nanorods, is presented. These block copolymers consist of a short anchor block (based on dopamine) and a long, easily graphitizable block of polyacrylonitrile. The grafting of such block copolymers to TiO2 nanorods creates a polymer shell, which can be visualized by atomic force microscopy (AFM). Thermal treatment at 700 °C converts the polyacrylonitrile block to partially graphitic structures (as determined by Raman spectroscopy), establishing a thin carbon coating (as determined by transmission electron microscopy, TEM, analysis). The carbon-coated TiO2 nanorods show improved electrochemical performance in terms of achievable specific capacity and, particularly, long-term cycling stability by reducing the average capacity fading per cycle from 0.252 mAh g(-1) to only 0.075 mAh g(-1) .

  19. Static vs dynamic settlement and adhesion of diatoms to ship hull coatings.

    PubMed

    Zargiel, Kelli A; Swain, Geoffrey W

    2014-01-01

    Many experiments utilize static immersion tests to evaluate the performance of ship hull coatings. These provide valuable data; however, they do not accurately represent the conditions both the hull and fouling organisms encounter while a ship is underway. This study investigated the effect of static and dynamic immersion on the adhesion and settlement of diatoms to one antifouling coating (BRA 640), four fouling-release coatings (Intersleek(®) 700, Intersleek(®) 900, Hempasil X3, and Dow Corning 3140) and one standard surface (Intergard(®) 240 Epoxy). Differences in community composition were observed between the static and dynamic treatments. Achnanthes longipes was present on all coatings under static immersion, but was not present under dynamic immersion. This was also found for diatoms in the genera Bacillaria and Gyrosigma. Melosira moniformis was the only diatom present under dynamic conditions, but not static conditions. Several common fouling diatom genera were present on panels regardless of treatment: Amphora, Cocconeis, Entomoneis Cylindrotheca, Licmophora, Navicula, Nitzschia, Plagiotropis, and Synedra. Biofilm adhesion, diatom abundance and diatom diversity were found to be significantly different between static and dynamic treatments; however, the difference was dependent on coating and sampling date. Several coatings (Epoxy, DC 3140 and IS 700) had significantly higher biofilm adhesion on dynamically treated panels on at least one of the four sampling dates, while all coatings had significantly higher diatom abundance on at least one sampling date. Diversity was significantly greater on static panels than dynamic panels for Epoxy, IS 700 and HX3 at least once during the sampling period. The results demonstrate how hydrodynamic stress will significantly influence the microfouling community. Dynamic immersion testing is required to fully understand how antifouling surfaces will respond to biofilm formation when subjected to the stresses experienced

  20. Diatom community structure on commercially available ship hull coatings.

    PubMed

    Zargiel, Kelli A; Coogan, Jeffrey S; Swain, Geoffrey W

    2011-10-01

    Diatoms are primary colonizers of both antifouling and fouling-release ship hull coatings. There are few published studies which report on diatom community development on modern ship hull coatings. This study reports diatom communities on eight commercial marine ship hull coatings exposed at three static immersion sites along the east coast of Florida, viz. Daytona, Sebastian, and Miami. The coatings tested were three ablative copper systems (Ameron ABC-3, International BRA-640, and Hempel Olympic 76600), two copper-free biocidal systems (E-Paint SN-1, Sherwin Williams HMF), and three fouling-release (FR) systems (International Intersleek 700, International Intersleek 900, and Hempel Hempasil). One hundred and twenty-seven species comprising 44 genera were identified, including some of the more commonly known foulers, viz. Achnanthes, Amphora, Cocconeis, Entomoneis, Licmophora, Melosira, Navicula, Nitzschia, Synedra, and Toxarium. A significant difference was seen among sites, with the more estuarine site, Sebastian, having lower overall diatom abundance and higher diversity than Daytona and Miami. Copper coatings were primarily fouled by Amphora delicatissima and Entomoneis pseudoduplex. Copper-free coatings were fouled by Cyclophora tenuis, A. delicatissima, Achnanthes manifera, and Amphora bigibba. FR surfaces were typified by C. tenuis, and several species of Amphora. The presence of C. tenuis is new to the biofouling literature, but as new coatings are developed, this diatom may be one of many that prove to be problematic for static immersion. Results show coatings can be significantly influenced by geographical area, highlighting the need to test ship hull coatings in locations similar to where they will be utilized.

  1. Nanobiomaterial Coatings in Dentistry.

    PubMed

    Choi, Andy H; Cazalbou, Sophie; Ben-Nissan, Besim

    2015-01-01

    During the last decade, there has been a major increase in the interest of nanostructured materials in advanced technologies for biomedical and dental clinical applications. Nanostructured materials are associated with a variety of applications within the dental and biomedical field, for example nanoparticles in drug delivery systems and nanostructured scaffolds in tissue engineering. More importantly, nanotechnology has also been linked with the modification of surface properties of synthetic implants in an attempt to improve their bioactivity, reliability and protection from the release of harmful or unnecessary metal ions. This is achieved through the use of nanocoatings and nanocomposite coatings. These new-generation coatings based on inorganic materials and biological materials such as proteins and peptides are currently investigated and applied. This chapter aims to give an overview of the recent advances in nanocoatings and their composites being investigated or used in dentistry.

  2. Hydroxyapatite coatings.

    PubMed

    Lacefield, W R

    1988-01-01

    Four coating techniques were evaluated to determine which is most suitable for producing a dense, highly adherent coating onto metallic and ceramic implant materials. Two of the selected coating methods have serious limitations for use in this particular application, and did not meet the specified criteria for satisfactory coating as defined in the initial stages of the study. For example, the dip coating-sintering technique was judged to be unsatisfactory because of the adverse effect of the high-temperature sintering cycle on the mechanical properties of the metallic substrate materials. These materials could not be used in load-bearing applications because of the excessive grain growth and loss of the wrought structure of both the commercially pure Ti and Ti-6Al-4V substrates, and the loss of ductility in the cast Co-Cr-Mo alloy. Another area of concern was that bond strength between the HA coating and the substrate was not high enough to insure that interfacial failure would not occur during the lifetime of the implant. The immersion-coating technique, in which the metal substrate is immersed into the molten ceramic, was shown in a previous study to be the best method of coating a bioreactive glass onto a Co-Cr-Mo implant. Heating HA above its melting temperature, however, caused undesired compositional and structural changes, and upon solidification very limited adherence between the modified ceramic and substrate material occurred under the conditions of this study. The HIP technique, in which the Ti powder substrate and the HA powder coating are sintered together in a high-pressure autoclave, shows great promise for the fabrication of high-quality composite implants. Initial studies have indicated that high-density Ti substrates with a small grain size that are well bonded to a dense HA coating can be produced under optimum conditions. Sintering and densification additives, such as SiO2 powder, do not appear to be necessary. The main drawback to this

  3. Effects of coating roughness and biofouling on ship resistance and powering.

    PubMed

    Schultz, Michael P

    2007-01-01

    Predictions of full-scale ship resistance and powering are made for antifouling coating systems with a range of roughness and fouling conditions. The estimates are based on results from laboratory-scale drag measurements and boundary layer similarity law analysis. In the present work, predictions are made for a mid-sized naval surface combatant at cruising speed and near maximum speed. The results indicate that slime films can lead to significant increases in resistance and powering, and heavy calcareous fouling results in powering penalties up to 86% at cruising speed. The present estimates show good agreement with results from full-scale ship power trials.

  4. Layer-by-layer assembled graphene-coated mesoporous SnO2 spheres as anodes for advanced Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Shahid, Muhammad; Yesibolati, Nulati; Reuter, M. C.; Ross, F. M.; Alshareef, H. N.

    2014-10-01

    We report layer-by-layer (LBL) assembly of graphene/carbon-coated mesoporous SnO2 spheres (Gr/C-SnO2 spheres), without binder and conducting additives, as anode materials with excellent Li-ion insertion-extraction properties. Our results indicate that these novel LBL assembled electrodes have high reversible Li storage capacity, improved cycling, and especially good rate performance, even at high specific currents. The superior electrochemical performance offered by these LBL assembled Gr/C-SnO2 spheres is attributed to the enhanced electronic conductivity and effective diffusion of Li ions in the interconnected network of nanoparticles forming the mesoporous SnO2 spheres.

  5. Poly(dimethyl siloxane) (PDMS) network blends of amphiphilic acrylic copolymers with poly(ethylene glycol)-fluoroalkyl side chains for fouling-release coatings. II. Laboratory assays and field immersion trials.

    PubMed

    Martinelli, Elisa; Sarvothaman, Mahesh K; Galli, Giancarlo; Pettitt, Michala E; Callow, Maureen E; Callow, James A; Conlan, Sheelagh L; Clare, Anthony S; Sugiharto, Albert B; Davies, Cait; Williams, David

    2012-01-01

    Amphiphilic copolymers containing different amounts of poly(ethylene glycol)-fluoroalkyl acrylate and polysiloxane methacrylate units were blended with a poly(dimethyl siloxane) (PDMS) matrix in different proportions to investigate the effect of both copolymer composition and loading on the biological performance of the coatings. Laboratory bioassays revealed optimal compositions for the release of sporelings of Ulva linza, and the settlement of cypris larvae of Balanus amphitrite. The best-performing coatings were subjected to field immersion tests. Experimental coatings containing copolymer showed significantly reduced levels of hard fouling compared to the control coatings (PDMS without copolymer), their performance being equivalent to a coating based on Intersleek 700™. XPS analysis showed that only small amounts of fluorine at the coating surface were sufficient for good antifouling/fouling-release properties. AFM analyses of coatings under immersion showed that the presence of a regular surface structure with nanosized domains correlated with biological performance.

  6. Advanced zinc phosphate conversion and pre-ceramic polymetallosiloxane coatings for corrosion protection of steel and aluminum, and characteristics of polyphenyletheretherketone-based materials. Final report

    SciTech Connect

    Sugama, T.; Carciello, N.R.

    1992-07-01

    Anhydrous zinc phosphate (Zn{center_dot}Ph) coatings deposited by immersing the steel in transition Co, Ni, and Mn cation-incorporated phosphating solutions were investigated. Two features for the anhydrous 340C-heated (Zn{center_dot}Ph) were addressed; one was to determine if electron trapping of adsorbed CO{sup 2+} and Ni{sup 2+} ions acts to inhibit the cathodic reaction on the (Zn{center_dot}Ph), and the second was to determine the less susceptibility of the {alpha}-Zn{sub 3}(PO{sub 4}){sub 2} phase to alkali-induced dissolution. The factors governing film-forming of pre-ceramic polymetallosiloxane (PMS) coatings for Al substrates were investigated. Four factors were important in obtaining a good film: (1) formation of organopolymetallosiloxane at sintering temperatures of 150C; (2) pyrolytic conversion at 350C into an amorphous PMS network structure in which the Si-O-M linkage were moderately enhanced; (3) noncrystalline phases; and (4) formation of interfacial oxane bond between PMS and Al oxide. Formation of well-crystallized polyphenyletheretherketone (PEEK) in vicinity of silica aggregates was found in the molted body made in N{sub 2}. Crystalline PEEK contributed to thermal and hydrothermal stabilities of mortar specimens at temperatures up to 200C, and resistance in 5 wt % H{sub 2}SO{sub 4} solution at 80C.

  7. Coated/Sandwiched rGO/CoSx Composites Derived from Metal-Organic Frameworks/GO as Advanced Anode Materials for Lithium-Ion Batteries.

    PubMed

    Yin, Dongming; Huang, Gang; Zhang, Feifei; Qin, Yuling; Na, Zhaolin; Wu, Yaoming; Wang, Limin

    2016-01-22

    Rational composite materials made from transition metal sulfides and reduced graphene oxide (rGO) are highly desirable for designing high-performance lithium-ion batteries (LIBs). Here, rGO-coated or sandwiched CoSx composites are fabricated through facile thermal sulfurization of metal-organic framework/GO precursors. By scrupulously changing the proportion of Co(2+) and organic ligands and the solvent of the reaction system, we can tune the forms of GO as either a coating or a supporting layer. Upon testing as anode materials for LIBs, the as-prepared CoSx -rGO-CoSx and rGO@CoSx composites demonstrate brilliant electrochemical performances such as high initial specific capacities of 1248 and 1320 mA h g(-1) , respectively, at a current density of 100 mA g(-1) , and stable cycling abilities of 670 and 613 mA h g(-1) , respectively, after 100 charge/discharge cycles, as well as superior rate capabilities. The excellent electrical conductivity and porous structure of the CoSx /rGO composites can promote Li(+) transfer and mitigate internal stress during the charge/discharge process, thus significantly improving the electrochemical performance of electrode materials.

  8. Compact test apparatus for evaluation of flow erosion of marine coatings

    NASA Astrophysics Data System (ADS)

    Debowski, M. A.; Quintana, R.; Lee, H. P.

    2015-10-01

    An apparatus designed and manufactured for evaluation of flow erosion of coatings or layers is presented in this paper. The setup was primarily designed for coatings intended to perform in dynamic marine environments but can be also used for evaluation using fresh water. The concept is based on an in-line flow test cell and modular design allowing good flexibility of varying testing parameters. The flow rate that can be achieved depends on the flow cell geometry and can reach 28 km/h (15 kn) with the presented setup. Temperature may be adjusted between 15 and 35 °C. Particle and metal ion filters are parts of this setup. The dimensions of the apparatus including all components do not exceed 2 m × 2 m × 2 m. The use of the apparatus is illustrated with the results of evaluation of self-polishing anti-fouling coatings and model, silicon wafer grafted layers.

  9. Antifouling steroids from the South China Sea gorgonian coral Subergorgia suberosa.

    PubMed

    Zhang, Jun; Liang, Yan; Wang, Kai-Ling; Liao, Xiao-Jian; Deng, Zhou; Xu, Shi-Hai

    2014-01-01

    Two new unusual cholestane derivatives, pentacyclic steroid 16,22-epoxy-20β,23S-dihydroxycholest-1-ene-3-one (1) and 20β,23S-dihydroxycholest-1-ene-3,22-dione (2), along with two new pregnane derivatives, 15β,17α-dihydroxypregna-4,6-diene-3,20-dione (3) and 11α-hydroxypregna-4-ene-3,6,20-trione (4), were isolated from the South China Sea gorgonian coral Subergorgia suberosa. Their structures were established based on the extensive analyses of 2D NMR, IR, and HRMS. Antifouling tests against Balanus amphitrite larvae settlement indicated that 1 and 2 exhibited inhibitory effect with EC50 values of 5.3, and 14.5 μg/mL, respectively.

  10. Are antifouling paint particles a continuous source of toxic chemicals to the marine environment?

    PubMed

    Soroldoni, Sanye; Abreu, Fiamma; Castro, Ítalo Braga; Duarte, Fabio Andrei; Pinho, Grasiela Lopes Leães

    2017-05-15

    Antifouling paint particles (APPs) are generated during periodical maintenance of boat hulls. Chemical composition and toxicity (either chronic or acute) of APPs found in the sediment was evaluated using the epibenthic copepod Nitokra sp. The APPs analyzed showed the presence of high levels of metals such as Cu (234,247±268μgg(-1)), Zn (112,404±845μgg(-1)) and the booster biocide DCOIT (0.13μgg(-1)). Even at low concentrations (as from 5mgg(-1) of APPs by mass of sediment) a significantly decrease in the fecundity was observed in laboratory tests. When the sediment was disturbed in elutriate test, a LC50 of 0.14% for APPs was found. This study was the first assessment of toxicity associated with the presence of APPs in sediment to benthic organisms, and it calls attention to the need of improving regulations in boatyards and marina areas.

  11. Antifouling activity in some benthic Antarctic invertebrates by "in situ" experiments at Deception Island, Antarctica.

    PubMed

    Angulo-Preckler, Carlos; Cid, Cristina; Oliva, Francesc; Avila, Conxita

    2015-04-01

    Competition for space is a remarkable ecological force, comparable to predation, producing a strong selective pressure on benthic invertebrates. Some invertebrates, thus, possess antimicrobial compounds to reduce surface bacterial growth. Antimicrobial inhibition is the first step in avoiding being overgrown by other organisms, which may have a negative impact in feeding, respiration, reproduction … The in situ inhibition of bacterial biofilm was used here as an indicator of antifouling activity by testing hydrophilic extracts of twelve Antarctic invertebrates. Using two different approaches (genetics and confocal techniques) different levels of activity were found in the tested organisms. In fact, differences within body parts of the studied organisms were determined, in agreement with the Optimal Defense Theory. Eight out of 15 extracts tested had negative effects on fouling after 28 days submerged in Antarctic waters. Thus, although chemical defenses may be quite species-specific in their ecological roles, these results suggest that different chemical strategies exist to deal with space competition.

  12. On the influence of the culture conditions in bacterial antifouling bioassays and biofilm properties: Shewanella algae, a case study

    PubMed Central

    2014-01-01

    Background A variety of conditions (culture media, inocula, incubation temperatures) are employed in antifouling tests with marine bacteria. Shewanella algae was selected as model organism to evaluate the effect of these parameters on: bacterial growth, biofilm formation, the activity of model antifoulants, and the development and nanomechanical properties of the biofilms. The main objectives were: 1) To highlight and quantify the effect of these conditions on relevant parameters for antifouling studies: biofilm morphology, thickness, roughness, surface coverage, elasticity and adhesion forces. 2) To establish and characterise in detail a biofilm model with a relevant marine strain. Results Both the medium and the temperature significantly influenced the total cell densities and biofilm biomasses in 24-hour cultures. Likewise, the IC50 of three antifouling standards (TBTO, tralopyril and zinc pyrithione) was significantly affected by the medium and the initial cell density. Four media (Marine Broth, MB; 2% NaCl Mueller-Hinton Broth, MH2; Luria Marine Broth, LMB; and Supplemented Artificial Seawater, SASW) were selected to explore their effect on the morphological and nanomechanical properties of 24-h biofilms. Two biofilm growth patterns were observed: a clear trend to vertical development, with varying thickness and surface coverage in MB, LMB and SASW, and a horizontal, relatively thin film in MH2. The Atomic Force Microscopy analysis showed the lowest Young modulii for MB (0.16 ± 0.10 MPa), followed by SASW (0.19 ± 0.09 MPa), LMB (0.22 ± 0.13 MPa) and MH2 (0.34 ± 0.16 MPa). Adhesion forces followed an inverted trend, being higher in MB (1.33 ± 0.38 nN) and lower in MH2 (0.73 ± 0.29 nN). Conclusions All the parameters significantly affected the ability of S. algae to grow and form biofilms, as well as the activity of antifouling molecules. A detailed study has been carried out in order to establish a biofilm model for further assays. The morphology and

  13. The effects of copper pyrithione, an antifouling agent, on developing zebrafish embryos.

    PubMed

    Almond, Kelly M; Trombetta, Louis D

    2016-03-01

    A substitute for the organotins has been the use of metal pyrithiones, principally zinc and copper (CuPT) as antifouling agents. Zebrafish, Danio rerio, embryos were exposed after fertilization to increasing concentrations of CuPT (2, 4, 8, 12, 16, 32 and 64 μg/L) for 24 h. Morphological abnormalities at 30, 96 and 120 hours post fertilization (hpf) were recorded. Abnormalities at concentrations of 12 μg/L and higher were observed. Notochords became severely twisted as concentrations increased. These distortions of the notochord originated in the tail at the lower concentrations and proceeded rostrally with increasing dose. Edema was observed in the cardiac and yolk sac regions at the 12 and 16 μg/L CuPT concentrations. Light microscopy showed disorganization of muscle fibers, disruption and distortion of the transverse myoseptum and vacuolization of the myocyte. Hatching was measured every 12 h for 5 days following the 24 h exposure. Hatching decreased in a dose dependent manner. At 120 hpf, 47 % of the 64 μg/L CuPT treated embryos hatched. Inductively coupled plasma atomic absorbance spectrophotometry (ICPAAS) revealed copper bioaccumulation in whole embryo tissue and was significantly elevated in 32 and 64 μg/L CuPT treatment groups as compared to controls. Lipid peroxidation end products were significantly increased in animals exposed to 32 and 64 μg/L of CuPT. These data demonstrate that oxidative stress may play a role in the toxicity. The abnormalities and deformities observed in fish larvae would significantly decrease survival in polluted aqua-systems and question the use of this product as an antifouling agent.

  14. Significance of antifouling paint flakes to the distribution of dichlorodiphenyltrichloroethanes (DDTs) in estuarine sediment.

    PubMed

    Wu, Chen-Chou; Bao, Lian-Jun; Tao, Shu; Zeng, Eddy Y

    2016-03-01

    Recently published literature indicated that dichlorodiphenyltrichloroethane (DDT)-containing antifouling paint flakes were heterogeneously distributed within estuarine sediments. However, the significance of antifouling paint flakes in the fate and transport of DDT compounds and other organic pollutants in estuarine sediment is yet to be adequately addressed. To fill this knowledge gap, estuarine sediment and paint flakes from cabin and boat surfaces were collected from a fishery base in Guangdong Province of South China and analyzed for DDT compounds. Coarse fractioned samples collected from the vicinity of boat maintenance facilities contained appreciable amounts of colorful particles, which were identified as paint flakes by Fourier transform infrared spectroscopy. The highest concentrations of DDXs (sum of DDTs and its metabolites) occurred in the heavy-density (>1.7 g cm(-3)) fraction of coarse-size (200-2000 μm) sediments from near the boat maintenance facilities, suggesting the importance of paint flakes in the distribution pattern of "hot spots" in estuarine sediment. Moreover, the desorption rates of DDT compounds from paint flakes and the heavy-density fraction of coarse-size sediment were both extremely slow. Apparently, unevenly distributed paint flakes in sediment can artificially inflate the sorption capacity of heavy-density sediment for DDT compounds, and therefore can substantially change the environmental fate and behavior of hydrophobic organic chemicals in estuarine sediment. Finally, commonly used source diagnostic indices of DDT compounds were mostly grain-size and density dependent in sediment, as a result of the occurrence of paint flakes, which may strongly compromise the outcome of any source diagnostics efforts.

  15. Incorporating bioavailability into management limits for copper in sediments contaminated by antifouling paint used in aquaculture.

    PubMed

    Simpson, Stuart L; Spadaro, David A; O'Brien, Dom

    2013-11-01

    Although now well embedded within many risk-based sediment quality guideline (SQG) frameworks, contaminant bioavailability is still often overlooked in assessment and management of contaminated sediments. To optimise management limits for metal contaminated sediments, we assess the appropriateness of a range methods for modifying SQGs based on bioavailability considerations. The impairment of reproduction of the amphipod, Melita plumulosa, and harpacticoid copepod, Nitocra spinipes, was assessed for sediments contaminated with copper from antifouling paint, located below aquaculture cages. The measurement of dilute acid-extractable copper (AE-Cu) was found to provide the most useful means for monitoring the risks posed by sediment copper and setting management limits. Acid-volatile sulfide was found to be ineffective as a SQG-modifying factor as these organisms live mostly at the more oxidised sediment water interface. SQGs normalised to %-silt/organic carbon were effective, but the benefits gained were too small to justify this approach. The effectiveness of SQGs based on AE-Cu was attributed to a small portion of the total copper being present in potentially bioavailable forms (typically<10% of the total). Much of the non-bioavailable form of copper was likely present as paint flakes in the form of copper (I) oxide, the active ingredient of the antifoulant formulation. While the concentrations of paint-associated copper are very high in some sediments, as the transformation of this form of copper to AE-Cu appears slow, monitoring and management limits should assess the more bioavailable AE-Cu forms, and further efforts be made to limit the release of paint particles into the environment.

  16. Green synthesis of graphene-silver nanocomposites and its application as a potent marine antifouling agent.

    PubMed

    Yee, Maxine Swee-Li; Khiew, Poi-Sim; Chiu, Wee Siong; Tan, Yuen Fen; Kok, Yih-Yih; Leong, Chee-Onn

    2016-12-01

    Fouling of marine surfaces has been a perpetual problem ever since the days of the early sailors. The tenacious attachment of seaweed and invertebrates to man-made surfaces, notably on ship hulls, has incurred undesirable economic losses. Graphene receives great attention in the materials world for its unique combination of physical and chemical properties. Herein, we present a novel 2-step synthesis method of graphene-silver nanocomposites which bypasses the formation of graphene oxide (GO), and produces silver nanoparticles supported on graphene sheets through a mild hydrothermal reduction process. The graphene-Ag (GAg) nanocomposite combines the antimicrobial property of silver nanoparticles and the unique structure of graphene as a support material, with potent marine antifouling properties. The GAg nanocomposite was composed of micron-scaled graphene flakes with clusters of silver nanoparticles. The silver nanoparticles were estimated to be between 72 and 86nm (SEM observations) while the crystallite size of the silver nanoparticles (AgNPs) was estimated between 1 and 5nm. The nanocomposite also exhibited the SERS effect. GAg was able to inhibit Halomonas pacifica, a model biofilm-causing microbe, from forming biofilms with as little as 1.3wt.% loading of Ag. All GAg samples displayed significant biofilm inhibition property, with the sample recording the highest Ag loading (4.9wt.% Ag) associated with a biofilm inhibition of 99.6%. Moreover, GAg displayed antiproliferative effects on marine microalgae, Dunaliella tertiolecta and Isochrysis sp. and inhibited the growth of the organisms by more than 80% after 96h. The marine antifouling properties of GAg were a synergy of the biocidal AgNPs anchored on the stable yet flexible graphene sheets, providing maximum active contact surface areas to the target organisms.

  17. Regulatory Aspects of Coatings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter gives a history of the development and uses of edible coating regulations, detailed chapters on coating caracteristics, determination of coating properties, methods for making coatings, and discription of coating film formers (polysaccharieds, lipids, resins, proteins). The chapter also...

  18. Initial bacterial deposition on bare and zeolite-coated aluminum alloy and stainless steel.

    PubMed

    Chen, Gexin; Beving, Derek E; Bedi, Rajwant S; Yan, Yushan S; Walker, Sharon L

    2009-02-03

    In this study, the impact of zeolite thin film coatings on bacterial deposition and "biofouling" of surfaces has been investigated in an aqueous environment. The synthesis of two types of zeolite coatings, ZSM-5 coated on aluminum alloy and zeolite A coated on stainless steel, and the characterization of the coated and bare metal surfaces are described. The extent of cell deposition onto the bare and zeolite-coated aluminum alloy and stainless steel surfaces is investigated in a parallel plate flow chamber system under a laminar flow conditions. The initial rates of bacterial transfer to the various surfaces are compared by utilizing a marine bacterium, Halomonas pacifica g, under a range of ionic strength conditions. H. pacifica g deposited onto bare metal surfaces to a greater extent as compared with cells deposited onto the zeolite coatings. The surface properties found to have the most notable effect on attachment are the electrokinetic and hydrophobicity properties of the metal and zeolite-coated surfaces. These results suggest that a combination of two chemical mechanisms-hydrophobic and electrostatic interactions-contribute to the antifouling nature of the zeolite surface. Additional observations on the relative role of the hydrodynamic and physical phenomena are also discussed.

  19. Highly durable superhydrophobic coatings with gradient density by movable spray method

    NASA Astrophysics Data System (ADS)

    Tenjimbayashi, Mizuki; Shiratori, Seimei

    2014-09-01

    Superhydrophobic surface is expected to be applied in anti-fouling, anti-icing, and anti-bacterial. However, practical use is interrupted by low mechanical strength, time-consuming process, and limited coating substrate. Here highly durable superhydrophobic coatings were prepared by simple and novel spraying method, which sprays with changing the "spray distance between substrate and spray" (SD), named "movable spray method." We prepared the solution that changes wettability and durability with spraying distance by mixing SiO2 nanoparticles and ethyl alpha cyanoacrylate polymer (EAC). Then, we evaluated the chemical components and surface morphologies of each spraying distance coatings (0 ˜ 50 cm) by XPS, SEM, and laser scanning microscope. It revealed that surface roughness and SiO2/EAC ratio increased as the SD increases. Thus, durable superhydrophobic coatings were designed by spraying with increasing SD gradually. Glow discharge-optical emission spectrometry analysis revealed that designed coatings showed the gradual increase of SiO2/EAC ratio. As a result, coatings prepared on glass, wood, or aluminum substrates maintained their superhydrophobicity up to the abrasion at 40 kPa. This movable spray method is simple coating by the wet process and prepares robust hydrophobic coating on complex shape and large area substrates. The gradient functional surface was found to have mechanical durability and superhydrophobicity, and wide area applications will be expected.

  20. Surface-initiated hyperbranched polyglycerol as an ultralow-fouling coating on glass, silicon, and porous silicon substrates.

    PubMed

    Moore, Eli; Delalat, Bahman; Vasani, Roshan; McPhee, Gordon; Thissen, Helmut; Voelcker, Nicolas H

    2014-09-10

    Anionic ring-opening polymerization of glycidol was initiated from activated glass, silicon, and porous silicon substrates to yield thin, ultralow-fouling hyperbranched polyglycerol (HPG) graft polymer coatings. Substrates were activated by deprotonation of surface-bound silanol functionalities. HPG polymerization was initiated upon the addition of freshly distilled glycidol to yield films in the nanometer thickness range. X-ray photoelectron spectroscopy, contact angle measurements, and ellipsometry were used to characterize the resulting coatings. The antifouling properties of HPG-coated surfaces were evaluated in terms of protein adsorption and the attachment of mammalian cells. The adsorption of bovine serum albumin and collagen type I was found to be reduced by as much as 97 and 91%, respectively, in comparison to untreated surfaces. Human glioblastoma and mouse fibroblast attachment was reduced by 99 and 98%, respectively. HPG-grafted substrates outperformed polyethylene glycol (PEG) grafted substrates of comparable thickness under the same incubation conditions. Our results demonstrate the effectiveness of antifouling HPG graft polymer coatings on a selected range of substrate materials and open the door for their use in biomedical applications.

  1. Westinghouse thermal barrier coatings development

    SciTech Connect

    Goedjen, J.G.; Wagner, G.

    1995-10-01

    Westinghouse, in conjunction with the Department of Energy and Oak Ridge National Laboratory, has embarked upon a program for the development of advanced thermal barrier coatings for industrial gas turbines. Development of thermal barrier coatings (TBC`s) for industrial gas turbines has relied heavily on the transfer of technology from the aerospace industry. Significant differences in the time/temperature/stress duty cycles exist between these two coating applications. Coating systems which perform well in aerospace applications may not been optimized to meet power generation performance requirements. This program will focus on development of TBC`s to meet the specific needs of power generation applications. The program is directed at developing a state-of-the-art coating system with a minimum coating life of 25,000 hours at service temperatures required to meet increasing operating efficiency goals. Westinghouse has assembled a team of university and industry leaders to accomplish this goal. Westinghouse will coordinate the efforts of all program participants. Chromalloy Turbine Technologies, Inc. and Sermatech International, Inc. will be responsible for bond coat and TBC deposition technology. Praxair Specialty Powders, Inc. will be responsible for the fabrication of all bond coat and ceramic powders for the program. Southwest Research Institute will head the life prediction modelling effort; they will also be involved in coordinating nondestructive evaluation (NDE) efforts. Process modelling will be provided by the University of Arizona.

  2. Effects of antifouling paint components (TBTO, copper and triazine) on the early development of embryos in cod (Gadus morhua L.).

    PubMed

    Granmo, A; Ekelund, R; Sneli, J A; Berggren, M; Svavarsson, J

    2002-10-01

    To assess the risk of antifoulant use to the commercially important cod (Gadus morhua L.), fertilised cod eggs were exposed to triazine, copper and TBTO singly or combined in laboratory tests with running seawater. At the highest tested concentrations (11.5 microg Cu l(-1); 5 microg TBTO l(-1)) larval mortality was increased. The highest concentration of triazine (40 microg l(-1)) did not cause any significant mortality. Fertilised eggs that had been exposed to all the three chemicals singly for five days showed a higher buoyancy than the controls. No synergistic or antagonistic effects were indicated. Embryos/larvae exposed to 0.004-0.8 microg TBTO l(-1) did not show any changed respiration compared to the controls after hatching. It is concluded that existing known field concentrations of the three antifoulants are hardly expected to cause detectable effects on fish embryonic/larval development.

  3. Zwitterionic peptide anchored to conducting polymer PEDOT for the development of antifouling and ultrasensitive electrochemical DNA sensor.

    PubMed

    Wang, Guixiang; Han, Rui; Su, Xiaoli; Li, Yinan; Xu, Guiyun; Luo, Xiliang

    2017-06-15

    Zwitterionic peptides were anchored to a conducting polymer of citrate doped poly(3,4-ethylenedioxythiophene) (PEDOT) via the nickel cation coordination, and the obtained peptide modified PEDOT, with excellent antifouling ability and good conductivity, was further used for the immobilization of a DNA probe to construct an electrochemical biosensor for the breast cancer marker BRCA1. The DNA biosensor was highly sensitive (with detection limit of 0.03fM) and selective, and it was able to detect BRCA1 in 5% (v/v) human plasma with satisfying accuracy and low fouling. The marriage of antifouling and biocompatible peptides with conducting polymers opened a new avenue to construct electrochemical biosensors capable of assaying targets in complex biological media with high sensitivity and without biofouling.

  4. Facile fabrication of bactericidal and antifouling switchable chitosan wound dressing through a 'click'-type interfacial reaction.

    PubMed

    Wang, Xianghong; Yuan, Shuaishuai; Guo, Yu; Shi, Dean; Jiang, Tao; Yan, Shunjie; Ma, Jiao; Shi, Hengchong; Luan, Shifang; Yin, Jinghua

    2015-12-01

    A facile approach to functionalize chitosan (CS) non-woven surface with the bactericidal and antifouling switchable moieties is presented. Azlactone-cationic carboxybetaine ester copolymer was firstly prepared, then chemically attached onto CS non-woven surface through the fast and efficient 'click'-type interfacial reaction between CS primary amines and azlactone moieties. The CS non-woven surface functionalized with cationic carboxybetaine esters is able to kill bacteria effectively. Upon the hydrolysis of carboxybetaine esters into zwitterionic groups, the resulting zwitterionic surface can further prevent the attachment of proteins, platelets, erythrocytes and bacteria. This CS non-woven that switches from bactericidal performance during storage to antifouling property before its service has great potential in wound dressing applications.

  5. Versatile Coating

    NASA Technical Reports Server (NTRS)

    1990-01-01

    A radome at Logan Airport and a large parabolic antenna at the Wang Building in Massachusetts are protected from weather, corrosion and ultraviolet radiation by a coating, specially designed for antennas and radomes, known as CRC Weathertite 6000. The CRC 6000 line that emerged from Boyd Coatings Research Co., Inc. is a solid dispersion of fluorocarbon polymer and polyurethane that yields a tough, durable film with superior ultraviolet resistance and the ability to repel water and ice over a long term. Additionally, it provides resistance to corrosion, abrasion, chemical attacks and impacts. Material can be used on a variety of substrates, such as fiberglass, wood, plastic and concrete in addition to steel and aluminum. In addition Boyd Coatings sees CRC 6000 applicability as an anti-icing system coated on the leading edge of aircraft wings.

  6. Protective Coating

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Inorganic Coatings, Inc.'s K-Zinc 531 protective coating is water-based non-toxic, non-flammable and has no organic emissions. High ratio silicate formula bonds to steel, and in 30 minutes, creates a very hard ceramic finish with superior adhesion and abrasion resistance. Improved technology allows application over a minimal commercial sandblast, fast drying in high humidity conditions and compatibility with both solvent and water-based topcoats. Coating is easy to apply and provides long term protection with a single application. Zinc rich coating with water-based potassium silicate binder offers cost advantages in materials, labor hours per application, and fewer applications over a given time span.

  7. Economic and environmental impacts on ports and harbors from the convention to ban harmful marine anti-fouling systems.

    PubMed

    Champ, Michael A

    2003-08-01

    The recent Diplomatic Conference held (1-5 October 2001) by the International Maritime Organization (IMO) in London adopted the Draft Convention prepared by The Marine Environmental Protection Committee (MEPC) of IMO for the "Control of Harmful Anti-fouling Systems for Ships." The convention has been developed to immediately ban the use of Tributyltin (TBT) globally in anti-fouling paints to "protect the marine environment". The ban on TBT has come about because TBT has detrimental effects on non-target marine organisms. In November 1999, IMO agreed that a treaty be developed by the MEPC to ensure a ban on the application of TBT based anti-fouling paints by 1 January 2003, and a ban on the use of TBT by 1 January 2008. At the meeting surious concern was expressed by some experts for the need to identify in the treaty the necessary regulatory language for: (1) the "safe" removal, treatment, and disposal of marine anti-foulants deemed "harmful" by the treaty and (2) who is liable for the future dredging and disposal of TBT-contaminated port and harbor sediments--to also "protect the marine environment". The requirement for "safe" removal and disposal was incorporated at MEPC 46 as Article 5 in the treaty, without it shipyards complying with existing national and local discharge regulations (most have none for discharge of TBT) could inadvertently release more TBT to ports and harbors in the five-year compliance period than has been leached from ships (hulls) in the past 40 years to the same waters. Virginia is the only State in the US that regulates the discharge to below 50 ng/l (50 parts per trillion). However, the liability for the future dredging and disposal costs of TBT-contaminated port and harbor sediments has not been addressed.

  8. Universal hydrophilic coating of thermoplastic polymers currently used in microfluidics.

    PubMed

    Zilio, Caterina; Sola, Laura; Damin, Francesco; Faggioni, Lucia; Chiari, Marcella

    2014-02-01

    A number of materials used to fabricate disposable microfluidic devices are hydrophobic in nature with water contact angles on their surface ranging from 80° to over 100°. This characteristic makes them unsuitable for a number of microfluidic applications. Both the wettability and analyte adsorption parameters are highly dependent on the surface hydrophobicity. In this article, we propose a general method to coat the surface of five materials: polydimethylsiloxane (PDMS), cyclic olefin copolymer (COC), polyethylene terephthalate (PET), polycarbonate (PC), and polytetrafluoroethylene (PTFE). This fast and robust process, which is easily implementable in any laboratory including microfabrication clean room facilities, was devised by combining gas-phase and wet chemical modification processes. Two different coatings that improve the surface hydrophilicity were prepared via the "dip and rinse" approach by immersing the plasma oxidized materials into an aqueous solution of two different poly(dimethylacrylamide) copolymers incorporating a silane moiety and functionalized with either N-acryloyloxysuccinimide (NAS) (poly(DMA-NAS-MAPS) or glycidyl methacrylate (GMA) (poly(DMA-GMA-MAPS). The coating formation was confirmed by contact angle (CA) analysis comparing the variation of CAs of uncoated and coated surfaces subjected to different aging treatments. The antifouling character of the polymer was demonstrated by fluorescence and interferometric detection of proteins adsorbed on the surafce. This method is of great interest in microfluidics due to its broad applicability to a number of materials with varying chemical compositions.

  9. Versatile antifouling polyethersulfone filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive.

    PubMed

    Zhao, Yi-Fan; Zhang, Pei-Bin; Sun, Jian; Liu, Cui-Jing; Yi, Zhuan; Zhu, Li-Ping; Xu, You-Yi

    2015-06-15

    Here we describe the development of versatile antifouling polyethersulfone (PES) filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive. Amphiphilic polyethersulfone-block-poly(2-hydroxyethyl methacrylate) (PES-b-PHEMA) was beforehand designed and used as the blending additive of PES membranes prepared by phase inversion technique. The surface enriched PHEMA blocks on membrane surface acted as an anchor to immobilize the initiating site. Poly(sulfobetaine methacrylate) (PSBMA) were subsequently grafted onto the PES blend membranes by surface-initiated atom transfer radical polymerization (SI-ATRP). The analysis of surface chemistry confirmed the successful grafting of zwitterionic PSBMA brushes on PES membrane surface. The resulted PES-g-PSBMA membranes were capable of separating proteins from protein solution and oil from oil/water emulsion efficiently. Furthermore, the modified membranes showed high hydrophilicity and strongly antifouling properties due to the incorporation of well-defined PSBMA layer. In addition, the PES-g-PSBMA membranes exhibited excellent blood compatibility and durability during the washing process. The developed antifouling PES membranes are versatile and can find their applications in protein filtration, blood purification and oil/water separation, etc.

  10. Hydration effects and antifouling properties of poly(vinyl chloride-co-PEGMA) membranes studied using molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Shaikh, Abdul Rajjak; Rajabzadeh, Saeid; Matsuo, Ryuichi; Takaba, Hiromitsu; Matsuyama, Hideto

    2016-04-01

    Polyvinyl chloride (PVC) membranes are widely used in water treatment because of their low cost and chemical stability. However, PVC membranes can become fouled, and this restricts their applications in membrane technology. In order to enhance the antifouling property of PVC membranes, copolymers such as poly(vinyl chloride-co-poly(ethylene glycol)methyl ether methacrylate) (poly(VC-co-PEGMA)) with different PEGMA segment percentages were synthesized in our previous work. Experimentally, it was observed that the poly(VC-co-PEGMA) copolymer has better antifouling properties than those of PVC membranes. Here, we explore effect of the PEGMA segment percentage on the surface hydration properties of poly(VC-co-PEGMA) copolymers. Density functional theory calculations and molecular dynamics simulations were carried out to understand the interactions between PVC and PEGMA. Model structures of these systems were validated by comparing the simulated values of their volumetric properties with the experimental values. MD studies showed that increasing PEGMA percentage in the copolymer increases the interaction with water molecules, leading to improved resistance to fouling. The antifouling mechanism is also discussed with respect to surface hydration and water dynamicity. This study could form a basis for the systematic studies of polymeric membranes as well as their stability from the extent of solvent-polymer, solvent-solvent, and polymer-polymer interactions.

  11. Biofouling Growth in Cold Estuarine Waters and Evaluation of Some Chitosan and Copper Anti-Fouling Paints

    PubMed Central

    Pelletier, Émilien; Bonnet, Claudie; Lemarchand, Karine

    2009-01-01

    Ecological concerns about antifouling paints containing non-green tin and copper compounds have highlighted the need for environmentally friendly alternatives. We report here a field test conducted in estuarine waters over two months designed to evaluate the efficiency of a number of active natural and man-made chemical ingredients added into a silicon-polyurethane marine paint. Early steps of biofouling in cold seawater of the St. Lawrence Estuary (Canada) were observed. Analyses, including dry biomass, flow cytometry and spectrofluorimetry, demonstrated a short-term antibacterial action of chitosan-based paints although no significant anti-algal action was observed. Cuprous oxide paints were efficient against bacteria and algae invasion in the first two weeks, especially those with added organic biocides such as isothiazolone and copper pyrithione. However, the overall dry biomass and chlorophyll a content were similar for all chitosan-and copper-based paints after 63 days. Microscopic observations revealed variation in the highly diverse benthic diatom population including species Navicula, Melosira, Cocconeis, Nitshzcia, Fragilaria and Amphora. Results suggest no real long-term efficiency for tested antifouling paints and highlight a particular need for green antifouling ingredients that are active under northern estuarine conditions. PMID:19742133

  12. Enhanced antifouling behaviours of polyvinylidene fluoride membrane modified through blending with nano-TiO2/polyethylene glycol mixture

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Wang, Zhiwei; Zhang, Xingran; Zheng, Xiang; Wu, Zhichao

    2015-08-01

    Titanium dioxide (TiO2) nanoparticles/polyethylene glycol (PEG) mixture was used to modify polyvinylidene fluoride (PVDF) membranes aiming to improve their antifouling ability. The use of PEG could improve the dispersion of nanoparticles thanks to steric hindrance effects. Test results showed that compared to the original PVDF membrane, the modified membranes had higher hydrophilicity and lower negative Zeta potential, facilitating membrane fouling control. The extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) analysis indicated that the addition of TiO2 nanoparticles improved their electron donor monopolarity, i.e., enhanced electron-donating ability. The interaction energy barrier between soluble microbial products (SMP) and membrane surfaces was also improved, indicating that anti-fouling ability of the modified membrane was elevated. The optimal dosage of nano-TiO2 was found to be 0.15%, and further increase of dosage resulted in the aggregation of nanoparticles which consequently impaired the modification efficiency. Quartz crystal microbalance with dissipation (QCM-D) monitoring and SMP filtration tests confirmed the antifouling ability of the modified membrane.

  13. Biofouling growth in cold estuarine waters and evaluation of some chitosan and copper anti-fouling paints.

    PubMed

    Pelletier, Emilien; Bonnet, Claudie; Lemarchand, Karine

    2009-07-14

    Ecological concerns about antifouling paints containing non-green tin and copper compounds have highlighted the need for environmentally friendly alternatives. We report here a field test conducted in estuarine waters over two months designed to evaluate the efficiency of a number of active natural and man-made chemical ingredients added into a silicon-polyurethane marine paint. Early steps of biofouling in cold seawater of the St. Lawrence Estuary (Canada) were observed. Analyses, including dry biomass, flow cytometry and spectrofluorimetry, demonstrated a short-term antibacterial action of chitosan-based paints although no significant anti-algal action was observed. Cuprous oxide paints were efficient against bacteria and algae invasion in the first two weeks, especially those with added organic biocides such as isothiazolone and copper pyrithione. However, the overall dry biomass and chlorophyll a content were similar for all chitosan-and copper-based paints after 63 days. Microscopic observations revealed variation in the highly diverse benthic diatom population including species Navicula, Melosira, Cocconeis, Nitshzcia, Fragilaria and Amphora. Results suggest no real long-term efficiency for tested antifouling paints and highlight a particular need for green antifouling ingredients that are active under northern estuarine conditions.

  14. High-Performance Polyimide Powder Coatings

    NASA Technical Reports Server (NTRS)

    Leahy, Jonathan J.

    2014-01-01

    Researchers at NASA's Kennedy Space Center have developed advanced powder coatings for longer-lasting, improved corrosion control. The results of preliminary tests of the coatings and their resistance to salt spray corrosion are very encouraging, and commercial partners are sought for further development.

  15. Free-standing electrodes composed of carbon-coated Li4Ti5O12 nanosheets and reduced graphene oxide for advanced sodium ion batteries

    NASA Astrophysics Data System (ADS)

    Xu, Guobao; Tian, Ye; Wei, Xiaolin; Yang, Liwen; Chu, Paul K.

    2017-01-01

    A free-standing electrode composed of carbon-coated Li4Ti5O12 nanosheets and reduced graphene oxide (designated as LTO-C/RGO) is fabricated for Na storage by modified vacuum filtration and subsequent annealing. In this process, graphene oxide with negative charges and LTO-C nanosheets with abundant charged ions are self-assembled into the nanocomposite based on the screening effect of electrostatic repulsion. The unique structure of the confined LTO-C nanosheets in a highly conductive interconnected RGO network not only promotes the reaction kinetics and structural stability of the electrodes during Na+ insertion/extraction, but also provides plenty of interfacial sites for Na+ adsorption giving rise to additional interfacial Na storage. The free-standing LTO-C/RGO anode for sodium ion battery exhibits a high capacity of 166 mAhg-1 at 1 C, good rate capability of 98.7 mAhg-1 at 5 C, and superior cyclic performance of 114 mAhg-1 at 2 C after 600 cycles. The materials boasting superior Na storage have large potential in high-performance sodium ion batteries in portable, flexible and wearable electronics.

  16. Eddy Current Assessment of Duplex Metallic Coatings

    NASA Astrophysics Data System (ADS)

    Krzywosz, K. J.

    2004-02-01

    EPRI is involved in a multi-year program with the Department of Energy to test, evaluate, and develop a field-deployable eddy current NDE system for life assessment of blade coatings for advanced gas turbines. The coatings evaluated from these advanced GE engines include CoCrAlY (GT 29) and NiCoCrAlY (GT 33) bond coats followed by top aluminide overlay coatings. These duplex metallic coatings commonly referred to as GT 29+ and GT 33+ coatings, respectively. In general, during cycling and continuous operation at higher operating temperature, coatings fail due to spallation of protective oxide layers, leading to consumption of protective coating by oxidation and to eventual failure of blades. To extend service life of these critical rotating components, an inspection-based condition assessment program has been initiated to help establish more optimum inspection intervals that are not dependent on time-in-service maintenance approach. This paper summarizes the latest results obtained to date using the state-of-the-art frequency-scanning eddy current tester with a built-in three-layer inversion analysis algorithm. Significant progress has been made in assessing and discriminating the duplex metallic coatings as normal, degraded, and/or cracked. In addition, quantitative assessment was conducted by estimating various coating and substrate conductivity values.

  17. Synthesis of cuprous oxide epoxy nanocomposite as an environmentally antimicrobial coating.

    PubMed

    M El Saeed, Ashraf; Abd El-Fattah, M; Azzam, Ahmed M; Dardir, M M; Bader, Magd M

    2016-08-01

    Cuprous oxide is commonly used as a pigment; paint manufacturers begin to employ cuprous oxide as booster biocides in their formulations, to replace the banned organotins as the principal antifouling compounds. Epoxy coating was reinforced with cuprous oxide nanoparticles (Cu2O NPs). The antibacterial as well as antifungal activity of Cu2O epoxy nanocomposite (Cu2O EN) coating films was investigated. Cu2O NPs were also experimented for antibiofilm and time-kill assay. The thermal stability and the mechanical properties of Cu2O EN coating films were also investigated. The antimicrobial activity results showed slowdown, the growth of organisms on the Cu2O EN coating surface. TGA results showed that incorporating Cu2O NPs into epoxy coating considerably enhanced the thermal stability and increased the char residue. The addition of Cu2O NPs at lower concentration into epoxy coating also led to an improvement in the mechanical resistance such as scratch and abrasion. Cu2O NPs purity was confirmed by XRD. The TEM photograph demonstrated that the synthesized Cu2O NPs were of cubic shape and the average diameter of the crystals was around 25nm. The resulting perfect dispersion of Cu2O NPs in epoxy coating revealed by SEM ensured white particles embedded in the epoxy matrix.

  18. An ecological risk assessment for the use of Irgarol 1051 as an algaecide for antifoulant paints.

    PubMed

    Hall, L W; Giddings, J M; Solomon, K R; Balcomb, R

    1999-07-01

    Irgarol 1051 is an algaecide used in copper-based antifoulant paints for controlling fouling organisms on the hulls of recreational and commercial watercraft. Paints containing this algaecide have been used in Europe since the mid-1980s. In 1998, the first antifouling paints containing Irgarol 1051 were registered for use in the U. S. To examine the risk that Irgarol may pose to aquatic ecosystems, a probabilistic ecological risk assessment was conducted using distributions of exposure and toxicity data. Exposure data for this assessment were derived from 11 monitoring studies (146 stations) conducted in marinas, estuaries, and coastal waters from 1992 to 1997 in six European countries. A comparison of 90th percentile concentrations pooled by station types across all regions showed that concentrations in marinas (316 ng/l) were higher than in estuaries and coastal waters (41 and 19 ng/l, respectively). A 90th percentile of 133 ng/l was reported for all pooled stations. Temporal trends showed that Irgarol concentrations typically peaked in early summer after launching of small boats with much lower concentrations occurring during the spring, fall, and winter. Toxicity data used for this risk assessment were derived primarily from unpublished studies submitted to regulatory agencies. Because Irgarol is a photosynthesis-inhibiting herbicide, it is much more toxic to plants than animals. Toxicity values for animals (fish and invertebrates) were much greater than concentrations of Irgarol reported in the environment. Therefore, a conservative approach using a distribution of only plant toxicity data (EC50s for plant growth) was used to derive a 10th percentile of 136 ng/l. This plant toxicity benchmark of 136 ng/l was used for risk characterization. Results from probabilistic analysis showed that ecological risk from Irgarol exposure was low in estuaries, coastal areas, and various open-type marinas. However, 10% or more of the plant species in enclosed marinas with low

  19. Novel antifouling agent-zinc pyrithione: stress induction and genotoxicity to the marine mussel Mytilus galloprovincialis.

    PubMed

    Marcheselli, Marco; Azzoni, Paola; Mauri, Marina

    2011-03-01

    The anti-fouling biocide zinc pyrithione (ZnPT) was recently demonstrated to be more persistent than expected in the coastal environment, and to have a potential for bioaccumulation. We investigated the occurrence of adverse effects in the marine mussel Mytilus galloprovincialis when exposed to non-lethal concentrations of the contaminant (0.2 and 0.4μM ZnPT), through the use of a battery of biomarkers from the molecular to the individual level. In particular, the expression of HSP27, HSP60, HSP70 and the presence of genotoxic damage were investigated in the gills and digestive gland of mussels by means of Western blot and TUNEL procedures, respectively. In addition, a stress on stress response test was performed in order to highlight a possible general stress conditions in the exposed bivalves. A concentration of 0.2μM ZnPT was found sufficient to trigger a marked stress response in gills and digestive gland, and a concentration-dependent HSP expression was highlighted. Moreover, at the tested concentrations, ZnPT was found able to induce genotoxic effects, as demonstrated by an amplified DNA fragmentation (up to +37% of TUNEL positive cells in comparison to the control group) and by an increased frequency of apoptotic cells (up to +5%) in the tissues of the exposed mussels. In addition, the stress on stress response test demonstrated a heavily decreased tolerance to anoxic conditions in mussels exposed to the higher tested concentration of the biocide (LT(50)=5.4 days) compared to the control individuals (LT(50)=10.7 days). Multivariate analyses highlighted a strong correspondence between the observed biological effects in M. galloprovincialis, HSP over-expression and DNA damage in the gills and digestive gland, and the bioaccumulation levels of the biocide. Data presented here indicate the need for further investigations on the ZnPT effects on the key species of marine coastal communities, with the aim of obtaining the necessary information for a sound risk

  20. Toxic effects of new antifouling compounds on tunicate haemocytes I. Sea-nine 211 and chlorothalonil.

    PubMed

    Cima, Francesca; Bragadin, Marcantonio; Ballarin, Loriano

    2008-01-31

    After the definitive ban on tin-based antifouling substances, new organic compounds have recently been introduced in antifouling paint formulations, as either principal or booster biocides. In most cases, previous risk assessment of these biocides has been inadequate so that their possible effects on aquatic ecosystems is a matter of great concern. We studied the effects of two new organic biocides often associated in paint formulations, Sea-Nine 211 (4,5 dichloro-2-n-octyl-4-isothiazoline-3-one) and chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile), on haemocytes of the compound ascidian Botryllus schlosseri exposed for 60 min to various concentrations (from 0.1 to 10 microM) of the xenobiotics. This species had previously proved to be a good bioindicator of organotin compounds. Both compounds, at concentrations of 1 and 10 microM, altered the morphology of phagocytes, and these changes were closely related to disrupting effects on cytoskeletal components. At the same concentrations, phagocytosis, which requires cytoskeletal modifications for pseudopod formation, was severely hindered. Both compounds were able to induce apoptosis of Botryllus blood cells, probably as a consequence of severe oxidative stress related to the reported decrease of intracellular reduced glutathione (GSH) content. In the case of Sea-Nine 211, a substantial increase in intracellular Ca(2+) and a negative effect on Ca(2+)-ATPase activity may also be involved in the activation of the cell death machinery. Cytochrome-c-oxidase was also significantly inhibited by the two biocides, indicating perturbation of the mitochondrial respiratory chain. Isodynamic mixtures of Sea-Nine 211 and chlorothalonil were used to evaluate the occurrence of interactions between the two compounds. Results suggest the combined action of partial additivity when cell-spreading and cytochrome-c-oxidase activity were considered, and were indicative of antagonism in the case of the GSH depletion. On the whole, our